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Sample records for iron-rich montmorillonite clay

  1. Novel applications of locally sourced montmorillonite (MMT) clay as ...

    African Journals Online (AJOL)

    This work explores the application of a locally sourced raw material, montmorillonite (MMT) clay, as a disintegrant in the formulation of an analgesic pharmaceutical product - paracetamol. The raw MMT was refined and treated with 0.IM NaCl to yield sodium montmorillonite (NaMMT) and the powder properties established in ...

  2. Adsorption of copper ions of natural montmorillonite clay

    Directory of Open Access Journals (Sweden)

    Pimneva Ludmila

    2017-01-01

    Full Text Available The prospects of montmorillonite clay using for the extraction of copper ions from natural and waste waters were determined. Specified chemical and phase composition of natural forms of the montmorillonite clay are shown in the article. Quantitative characteristics of adsorption process of copper ions, the statistical exchange capacity is 1,21 (298 К, 1,25 (313 К, 1,43 (333 К. The authors have studied the balance of copper ions by the method of constructing the isotherms. The description of the adsorption process was carried out by the Langmuir, Freundlich and Temkin models. The calculations showed that the best data for the sorption described by Langmuir model. The nature of the interaction of copper ions with montmorillonite clay in natural form is presented. The calculated thermodynamic parameters of the adsorption process, the obtained values of the Gibbs energy have a negative sign -11,5 (298 К, -15,6 (313 К, -16,2 (333 К кJ/mol, that corresponds to a sustainable consolidation of copper ions on the surface of the montmorillonite clay.

  3. Microstructures and physical properties of "backfill" clays: comparison of residua and sedimentary montmorillonite clays

    Czech Academy of Sciences Publication Activity Database

    Přikryl, R.; Ryndová, T.; Boháč, J.; Weishauptová, Zuzana

    2003-01-01

    Roč. 23, 1-4 (2003), s. 149-156 ISSN 0169-1317 R&D Projects: GA AV ČR IAA2046101 Institutional research plan: CEZ:AV0Z3046908 Keywords : bentonite * montmorillonite-rich clay * hydrophysical properties Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.287, year: 2003

  4. Molecular dynamics simulation of polyacrylamides in potassium montmorillonite clay hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Junfang [CSIRO Petroleum Resources, Ian Wark Laboratory, Bayview Avenue, Clayton, Victoria 3168 (Australia); Rivero, Mayela [CSIRO Petroleum, PO Box 1130, Bentley, Western Australia, 6102 (Australia); Choi, S K [CSIRO Petroleum Resources, Ian Wark Laboratory, Bayview Avenue, Clayton, Victoria 3168 (Australia)

    2007-02-14

    We present molecular dynamics simulation results for polyacrylamide in potassium montmorillonite clay-aqueous systems. Interlayer molecular structure and dynamics properties are investigated. The number density profile, radial distribution function, root-mean-square deviation (RMSD), mean-square displacement (MSD) and diffusion coefficient are reported. The calculations are conducted in constant NVT ensembles, at T = 300 K and with layer spacing of 40 A. Our simulation results showed that polyacrylamides had little impact on the structure of interlayer water. Density profiles and radial distribution function indicated that hydration shells were formed. In the presence of polyacrylamides more potassium counterions move close to the clay surface while water molecules move away, indicating that potassium counterions are hydrated to a lesser extent than the system in which no polyacrylamides were added. The diffusion coefficients for potassium and water decreased when polyacrylamides were added.

  5. Preparation and characterization of nano gold supported over montmorillonite clays

    International Nuclear Information System (INIS)

    Suraja, P.V.; Binitha, N.N.; Yaakob, Z.; Silija, P.P.

    2009-01-01

    Full text: The use of montmorillonite clays as a matrix, or as a host, for obtaining intercalated/supported metal particles has potential applications in catalysis and other areas. The gold nanoparticles were obtained from the most common anionic gold precursor HAuCl 4 ·3H 2 O by deposition-precipitation (DP) methods. However, it is difficult to prepare nano scale gold catalysts supported on silica surfaces with lower isoelectric point (IEP). Homogeneous precipitation method using urea also fails on silica surfaces. Reasons for the inefficiency of these methods are the negative charge of the metal precursor as well as the support surface and the high pH required for depositing gold nanoparticles. In the present work, we use glucose as the reductant in the presence of stabilizer for preparation of nano gold supported on montmorillonite clay. Here there is no need of increasing the pH of the solution to reduce the Au 3+ ions. The prepared systems are characterized using various techniques such as using X-ray fluorescence (XRF), UV-Vis Diffuse reflectance spectra (DRS) and Fourier Transform infra red spectra (FTIR) to prove the efficiency of the present method. (author)

  6. Preparation and Characterization of Nano Gold Supported over Montmorillonite Clays

    Energy Technology Data Exchange (ETDEWEB)

    Suraja, P V; Binitha, N N; Yaakob, Z; Silija, P P, E-mail: binithann@yahoo.co.in [Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, National University of Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2011-02-15

    The use of montmorillonite clays as a matrix, or as a host, for obtaining intercalated/supported metal particles has potential applications in catalysis and other areas. The gold nanoparticles were obtained from the most common anionic gold precursor HAuCl4{center_dot}3H2O by deposition-precipitation (DP) methods. However, it is difficult to prepare nanoscale gold catalysts supported on silica surfaces with lower isoelectric point (IEP). Homogeneous precipitation method using urea also fails on silica surfaces. Reasons for the inefficiency of these methods are the negative charge of the metal precursor as well as the support surface and the high pH required for depositing gold nanoparticles. In the present work, we use glucose as the reductant in the presence of stabilizer for preparation of nano gold supported on montmorillonite clay. There is no need of increasing the pH of the solution to reduce the Au3+ ions. The prepared systems are characterized using various techniques such as using X-ray fluorescence (XRF), UV-VIS Diffuse reflectance spectra (DRS) and Fourier Transform infra red spectra (FTIR) to prove the efficiency of the present method.

  7. Application of iron-rich natural clays in Camlica, Turkey for boron sorption from water and its determination by fluorimetric-azomethine-H method

    International Nuclear Information System (INIS)

    Seyhan, Serap; Seki, Yoldas; Yurdakoc, Mueruevvet; Merdivan, Melek

    2007-01-01

    In this study, iron-rich natural Camlica Bentonites, CB1 and CB2, were used for the sorption of boron in water samples. Boron was determined by newly progressed fluorimetric azomethine-H method. The optimum conditions found using factorial designs are pH 10, 45 deg. C, 0.250 g of clay and 20 mL of sample volume. It was found that 180 min is enough time for the equilibrium state to be reached in boron adsorption. At these conditions, boron sorption percentage was 80% for CB1 and 30% for CB2. The adsorption isotherms are well described by linear Freundlich model. Various geothermal waters in our country were also studied for boron sorption

  8. Verification of substitution of bentonites by montmorillonitic clays summary report on Czech montmorillonitic clays

    International Nuclear Information System (INIS)

    Carlson, L.; Keto, P.

    2006-10-01

    Czech bentonites and smectite-rich clays were characterised in order to study if they could be used as buffer and backfill materials instead of non-Czech commercial bentonites. The characterisation work was orgnized by RAWRA (the Czech Radioactive Waste Repository Authority) and the main part of the work was performed in the Czech Republic at Charles University and at Czech Technical University. Parallel and complementary characterisation was conducted in Finland in Sweden. This report was compiled with the aim to summarise the results, and to compare the methods and results gained in different testing laboratories. The characterisation included mineralogical, chemical and geotechnical investigations and experiments on thermal stability and sorption. There were some variations between the results gained in different laboratories. This was mainly due to differences between the testing methods used but also due to heterogeneity of the samples. The Czech bentonite-clays from Rokle and Strance clay deposits contained relatively high amount of swelling minerals and thus can be considered as potential buffer and backfill materials. (orig.)

  9. Experimental and theoretical study of Co sorption in clay montmorillonites

    Science.gov (United States)

    Gil Rebaza, A. V.; Montes, M. L.; Taylor, M. A.; Errico, L. A.; Alonso, R. E.

    2018-03-01

    Montmorillonite (MMT) clays are 2:1 layered structures which in natural state may allocate different hydrated cations such as M-nH2O (M = Na, Ca, Fe, etc) in its interlayer space. Depending on the capability for ion sorption, these materials are interesting for environmental remediation. In this work we experimentally study the Co sorption in a natural Na-MMT using UV-visible spectrometry and XRD on semi-oriented samples, and then analyze the sorption ability of this clay by means of ab initio calculation performed on pristine MMT. The structural properties of Na-MMT and Co-adsorbed MMT, and the hyperfine parameters at different atomic sites were analyzed and compared with the experimental ones for the first, and for the case of the hyperfine parameters, presented for the first time for the last. The theoretical predictions based on total energy considerations confirm that Co incorporation replacing Na is energetically favorable. Also, the basal spacing d001 experimentally obtained is well reproduced.

  10. Exfoliated polypyrrole-organically modified montmorillonite clay nanocomposite as a potential adsorbent for Cr (VI) removal

    CSIR Research Space (South Africa)

    Setshedi, KZ

    2013-01-01

    Full Text Available Exfoliated polypyrrole-organically modified montmorillonite clay nanocomposite (PPy OMMT NC), was prepared as a potential adsorbent, via in situ polymerization of pyrrole monomer for adsorption of toxic Cr(VI) from aqueous solution. The WAXD...

  11. Catalytic Ethanol Dehydration over Different Acid-activated Montmorillonite Clays.

    Science.gov (United States)

    Krutpijit, Chadaporn; Jongsomjit, Bunjerd

    2016-01-01

    In the present study, the catalytic dehydration of ethanol to obtain ethylene over montmorillonite clays (MMT) with mineral acid activation including H2SO4 (SA-MMT), HCl (HA-MMT) and HNO3 (NA-MMT) was investigated at temperature range of 200 to 400°C. It revealed that HA-MMT exhibited the highest catalytic activity. Ethanol conversion and ethylene selectivity were found to increase with increased reaction temperature. At 400°C, the HA-MMT yielded 82% of ethanol conversion having 78% of ethylene yield. At lower temperature (i.e. 200 to 300°C), diethyl ether (DEE) was a major product. The highest activity obtained from HA-MMT can be attributed to an increase of weak acid sites and acid density by the activation of MMT with HCl. It can be also proven by various characterization techniques that in most case, the main structure of MMT did not alter by acid activation (excepted for NA-MMT). Upon the stability test for 72 h during the reaction, the MMT and HA-MMT showed only slight deactivation due to carbon deposition. Hence, the acid activation of MMT by HCl is promising to enhance the catalytic dehydration of ethanol.

  12. Montmorillonite Clay Catalyzed Three Component, One-Pot Synthesis of 5-Hydroxyindole Derivatives

    International Nuclear Information System (INIS)

    Subba Reddy, B. V.; Sivaramakrishna Reddy, P.; Jayasudhan Reddy, Y.; Bhaskar, N.; Chandra Obula Reddy, B.

    2013-01-01

    A highly efficient and environmentally benign protocol has been developed for the first time to produce a wide range of biologically active 5-hydroxyindole derivatives using montmorillonite KSF clay as a reusable solid acid catalyst. The use of recyclable clay makes this procedure quite simple, more convenient and cost-effective

  13. On different photodecomposition behaviors of rhodamine B on laponite and montmorillonite clay under visible light irradiation

    KAUST Repository

    Wang, Peng; Cheng, Mingming; Zhang, Zhonghai

    2013-01-01

    In this study, laponite and montmorillonite clays were found to be able to decompose rhodamine B upon visible light irradiation (λ>420nm). Very interestingly, it was found that rhodamine B on laponite underwent a stepwise N-deethylation and its

  14. Calcium montmorillonite clay for the reduction of aflatoxin residues in milk and dairy products

    Science.gov (United States)

    In this study, dairy cows were treated with calcium montmorillonite clay (NovaSil Plus (NSP); BASF Corp., Ludwigshaven, Germany) in a replicated 5x5 Latin square design. The primary objectives were to determine if milk composition was altered following ingestion of NSP, and to investigate the abili...

  15. Synthesis and Characterization of the Hybrid Clay- Based Material Montmorillonite-Melanoidin: A Potential Soil Model

    Energy Technology Data Exchange (ETDEWEB)

    V Vilas; B Matthiasch; J Huth; J Kratz; S Rubert de la Rosa; P Michel; T Schäfer

    2011-12-31

    The study of the interactions among metals, minerals, and humic substances is essential in understanding the migration of inorganic pollutants in the geosphere. A considerable amount of organic matter in the environment is associated with clay minerals. To understand the role of organic matter in the environment and its association with clay minerals, a hybrid clay-based material (HCM), montmorillonite (STx-1)-melanoidin, was prepared from L-tyrosine and L-glutamic acid by the Maillard reaction. The HCM was characterized by elemental analysis, nuclear magnetic resonance, x-ray photoelectron spectroscopy (XPS), scanning transmission x-ray microscopy (STXM), and thermal analysis. The presence of organic materials on the surface was confirmed by XPS and STXM. The STXM results showed the presence of organic spots on the surface of the STx-1 and the characterization of the functional groups present in those spots. Thermal analysis confirmed the existence of organic materials in the montmorillonite interlayer, indicating the formation of a composite of melanoidin and montmorillonite. The melanoidin appeared to be located partially between the layers of montmorillonite and partially at the surface, forming a structure that resembles the way a cork sits on the top of a champagne bottle.

  16. On different photodecomposition behaviors of rhodamine B on laponite and montmorillonite clay under visible light irradiation

    KAUST Repository

    Wang, Peng

    2013-12-11

    In this study, laponite and montmorillonite clays were found to be able to decompose rhodamine B upon visible light irradiation (λ>420nm). Very interestingly, it was found that rhodamine B on laponite underwent a stepwise N-deethylation and its decomposition was terminated once rhodamine 110, as a decomposition product, was formed, whereas the same phenomenon was not observed for rhodamine B on montmorillonite, whose decomposition involved chromophore destruction. Mechanistic study revealed that the different photodecomposition behaviors of rhodamine B on laponite and montmorillonite were attributed to the oxidation by different reactive oxygen species, with laponite involving HO2/O2- while montmorillonite involving OH. It was also found that the degradation pathway of rhodamine B on laponite switched from N-deethylation to chromophore destruction when solution pH was changed from 7.0 to 3.0, which was attributed to a much higher fraction of HO2 relative to O2- under pH 3.0 than under pH 7.0. Based on the results, a mechanism of rhodamine dye decomposition on clay under visible light was proposed, involving the clay as an electron acceptor, electron relay between the adsorbed dye molecules and oxygen molecules, and subsequent reactions between the generated dye radical cations and different reactive oxygen species. The results of this study shed light on how to best utilize visible light for organic pollutant degradation on clays within engineered treatment systems as well as on many of naturally occurring pollutant degradation processes in soils and air involving clay. © 2013 King Saud University.

  17. Preliminary report on longevity of montmorillonite clay under repository-related conditions

    International Nuclear Information System (INIS)

    Pusch, R.; Karnland, O.

    1990-12-01

    This report summarizes current work on developing complete models for predicting the chemical stability of montmorillonitic bentonite buffer materials in HLW repositories. The major degrading mechanism is the conversion of montmorillonite to hydrous mica ('illite'), the basis of the derivation of tentative models being offered by ongoing systematic hydrothermal tests, which indicate that such conversion takes place by dissolution, yielding very mobile silica, and aluminium that tends to stay in the clay voids. The key mechanism in the transformation to hydrous mica at temperatures below about 130 degrees C is concluded to be neoformation of the latter mineral, the controlling parameter being the access to potassium. For temperatures ranging between 130 and 200 degrees C, excess silica is released by beidellitization and this yields I/S mixed layer minerals on uptake of potassium, and precipitation of cementing silica in the form of amorphous silica and cristobalite. The rate of transformation of montmorillonite to hydrous mica is still controlled by the access to potassium, i.e. by the rate at which potassium enters the clay. 10 Aa minerals that can be mistaken for hydrous mica can be formed by cementing collapsed stacks together. The models appear to give montmorillonite transformation rates that are in agreement with lab results and geological examples but further calibration, primarily by using the results of ongoing hydrothermal tests in the Stripa study, are required to make them applicable to repository conditions. (au)

  18. Surface Assisted Formation of methane Hydrates on Ice and Na Montmorillonite Clay

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Teich-McGoldrick, Stephanie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cygan, Randall Timothy [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Meserole, Stephen P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rodriguez, Mark A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-07-01

    Methane hydrates are extremely important naturally-occurring crystalline materials that impact climate change, energy resources, geological hazards, and other major environmental issues. Whereas significant experimental effort has been completed to understanding the bulk thermodynamics of methane hydrate assemblies, little is understood on heterogeneous nucleation and growth of methane hydrates in clay-rich environments. Controlled synthesis experiments were completed at 265-285 K and 6.89 MPa to examine the impact of montmorillonite surfaces in clay-ice mixtures to nucleate and form methane hydrate. The results suggest that the hydrophilic and methane adsorbing properties of Namontmorillonite reduce the nucleation period of methane hydrate formation in pure ice systems.

  19. Modified montmorillonite clay microparticles for stable oil-in-seawater emulsions.

    Science.gov (United States)

    Dong, Jiannan; Worthen, Andrew J; Foster, Lynn M; Chen, Yunshen; Cornell, Kevin A; Bryant, Steven L; Truskett, Thomas M; Bielawski, Christopher W; Johnston, Keith P

    2014-07-23

    Environmentally benign clay particles are of great interest for the stabilization of Pickering emulsions. Dodecane-in-synthetic seawater (SSW) emulsions formed with montmorillonite (MMT) clay microparticles modified with bis(2-hydroxyethyl)oleylamine were stable against coalescence, even at clay concentrations down to 0.1% w/v. Remarkably, as little as 0.001% w/v surfactant lowered the hydrophilicity of the clay to a sufficient level for stabilization of oil-in-SSW emulsions. The favorable effect of SSW on droplet size reduction and emulsion stability enhancement is hypothesized to be due to reduced electrostatic repulsion between adsorbed clay particles and a consequent increase in the continuous phase (an aqueous clay suspension) viscosity. Water/oil (W/O) emulsions were inverted to O/W either by decreasing the mass ratio of surfactant-to-clay (transitional inversion) or by increasing the water volume fraction (catastrophic inversion). For both types of emulsions, coalescence was minimal and the sedimentation or creaming was highly correlated with the droplet size. For catastrophic inversions, the droplet size of the emulsions was smaller in the case of the preferred curvature. Suspensions of concentrated clay in oil dispersions in the presence of surfactant were stable against settling. The mass transfer pathways during emulsification of oil containing the clay particles were analyzed on the droplet size/stability phase diagrams to provide insight for the design of dispersant systems for remediating surface and subsurface oceanic oil spills.

  20. Molecular Dynamics Simulations of Carbon Dioxide, Methane, and Their Mixture in Montmorillonite Clay Hydrates

    KAUST Repository

    Kadoura, Ahmad Salim

    2016-05-26

    Molecular dynamics simulations were carried out to study the structural and transport properties of carbon dioxide, methane, and their mixture at 298.15 K in Na-montmorillonite clay in the presence of water. The simulations show that, the self-diffusion coefficients of pure CO2 and CH4 molecules in the interlayers of Na-montmorillonite decrease as their loading increases, possibly because of steric hindrance. The diffusion of CO2 in the interlayers of Na-montmorillonite, at constant loading of CO2, is not significantly affected by CH4 for the investigated CO2/CH4 mixture compositions. We attribute this to the preferential adsorption of CO2 over CH4 in Na-montmorillonite. While the presence of adsorbed CO2 molecules, at constant loading of CH4, very significantly reduces the self-diffusion coefficients of CH4, and relatively larger decrease in those diffusion coefficients are obtained at higher loadings. The preferential adsorption of CO2 molecules to the clay surface screens those possible attractive surface sites for CH4. The competition between screening and steric effects leads to a very slight decrease in the diffusion coefficients of CH4 molecules at low CO2 loadings. The steric hindrance effect, however, becomes much more significant at higher CO2 loadings and the diffusion coefficients of methane molecules significantly decrease. Our simulations also indicate that, similar effects of water on both carbon dioxide and methane, increase with increasing water concentration, at constant loadings of CO2 and CH4 in the interlayers of Na-montmorillonite. Our results could be useful, because of the significance of shale gas exploitation and carbon dioxide storage.

  1. Molecular Dynamics Simulations of Carbon Dioxide, Methane, and Their Mixture in Montmorillonite Clay Hydrates

    KAUST Repository

    Kadoura, Ahmad Salim; Nair, Arun Kumar Narayanan; Sun, Shuyu

    2016-01-01

    Molecular dynamics simulations were carried out to study the structural and transport properties of carbon dioxide, methane, and their mixture at 298.15 K in Na-montmorillonite clay in the presence of water. The simulations show that, the self-diffusion coefficients of pure CO2 and CH4 molecules in the interlayers of Na-montmorillonite decrease as their loading increases, possibly because of steric hindrance. The diffusion of CO2 in the interlayers of Na-montmorillonite, at constant loading of CO2, is not significantly affected by CH4 for the investigated CO2/CH4 mixture compositions. We attribute this to the preferential adsorption of CO2 over CH4 in Na-montmorillonite. While the presence of adsorbed CO2 molecules, at constant loading of CH4, very significantly reduces the self-diffusion coefficients of CH4, and relatively larger decrease in those diffusion coefficients are obtained at higher loadings. The preferential adsorption of CO2 molecules to the clay surface screens those possible attractive surface sites for CH4. The competition between screening and steric effects leads to a very slight decrease in the diffusion coefficients of CH4 molecules at low CO2 loadings. The steric hindrance effect, however, becomes much more significant at higher CO2 loadings and the diffusion coefficients of methane molecules significantly decrease. Our simulations also indicate that, similar effects of water on both carbon dioxide and methane, increase with increasing water concentration, at constant loadings of CO2 and CH4 in the interlayers of Na-montmorillonite. Our results could be useful, because of the significance of shale gas exploitation and carbon dioxide storage.

  2. Effect of seawater on consistency, infiltration rate and swelling characteristics of montmorillonite clay

    Directory of Open Access Journals (Sweden)

    Mohie Eldin Elmashad

    2016-08-01

    Full Text Available This paper presents the results of an experimental investigation performed to quantify the effect of mixing clayey soils with saltwater on consistency and swelling characteristics of clays. Massive natural clay deposits and compacted clay backfills either exist or are used in certain important and sensitive applications such as dams, liners, barriers and buffers in waste disposal facilities. In many cases, the clay deposits in these applications are subjected to saltwater. However, in standard laboratory classification tests, distilled or potable water are usually used in mixing test samples. This may lead to faulty interpretation of the actual in-situ consistency and volume change behaviors. In this research, an attempt is made to quantify the changes in consistency and swelling of clay soils from various locations around the Nile valley and possessing a wide range of consistency, when mixed with natural seawater with different salt concentrations. The results showed that the increase of the salt concentration of the mixing water may result in major decrease in the liquid limit and swelling characteristics of high plasticity montmorillonite clays. The reduction in the swelling of the clay soils is also proportional to the rate of saltwater infiltration. In an attempt to correlate the swelling of clays to the rate of water infiltration, a new simplified laboratory apparatus is proposed where swelling and infiltration are measured in one simple test “the swelling infiltrometer”.

  3. Synthesis and characterization of montmorillonite clay intercalated with molecular magnetic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Marcel G.; Martins, Daniel O.T.A.; Carvalho, Beatriz L.C. de [Instituto de Química, Universidade Federal Fluminense, Niterói, RJ 24.020–150 (Brazil); Mercante, Luiza A. [Laboratório Nacional de Nanotecnologia para o Agronegócio (LNNA), Embrapa Instrumentação, São Carlos, SP 13560 970 (Brazil); Soriano, Stéphane [Instituto de Física, Universidade Federal Fluminense, Niterói, RJ 24.210 346 (Brazil); Andruh, Marius [Inorganic Chemistry Laboratory, Faculty of Chemistry, University of Bucharest, Str. Dumbrava Rosie nr. 23, Bucharest (Romania); Vieira, Méri D., E-mail: gqimeri@vm.uff.br [Instituto de Química, Universidade Federal Fluminense, Niterói, RJ 24.020–150 (Brazil); Vaz, Maria G.F., E-mail: mariavaz@vm.uff.br [Instituto de Química, Universidade Federal Fluminense, Niterói, RJ 24.020–150 (Brazil)

    2015-08-15

    In this work montmorillonite (MMT) clay, whose matrix was modified with an ammonium salt (hexadecyltrimethylammonium bromide – CTAB), was employed as an inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange: a nitronyl nitroxide derivative 2-[4-(N-ethyl)-pyridinium]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (p-EtRad{sup +}) and two binuclear coordination compounds, [Ni(valpn)Ln]{sup 3+}, where H{sub 2}valpn stands for 1,3-propanediyl-bis(2-iminomethylene-6-methoxy-phenol), and Ln=Gd{sup III}; Dy{sup III}. The pristine MMT and the intercalated materials were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and magnetic measurements. The X-ray diffraction data analysis showed an increase of the interlamellar space of the intercalated MMT, indicating the intercalation of the magnetic compounds. Furthermore, the magnetic properties of the hybrid compounds were investigated, showing similar behavior as the pure magnetic guest species. - Graphical abstract: Montmorillonite clay was employed as inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange - Highlights: • Montmorillonite was employed as a host material. • Three molecular magnetic compounds were intercalated through ion exchange. • The compounds were successful intercalated maintaining the layered structure. • The hybrid materials exhibited similar magnetic behavior as the pure magnetic guest.

  4. Origin of enhanced Brønsted acidity of NiF-modified synthetic mica-montmorillonite clay

    NARCIS (Netherlands)

    Liu, C.; Pidko, E.A.; Hensen, Emiel J M

    2018-01-01

    The Brønsted acidity of synthetic mica-montmorillonite (SMM) clay was studied by periodic DFT calculations. Different structural models were compared to determine the Brønsted acidity of protons of the SMM clay based on (i) isomorphous substitution of Si4+ by Al3+ in the

  5. Origin of enhanced Brønsted acidity of NiF-modified synthetic mica-montmorillonite clay

    NARCIS (Netherlands)

    Liu, Chong; Pidko, Evgeny A.; Hensen, Emiel J.M.

    2018-01-01

    The Brønsted acidity of synthetic mica-montmorillonite (SMM) clay was studied by periodic DFT calculations. Different structural models were compared to determine the Brønsted acidity of protons of the SMM clay based on (i) isomorphous substitution of Si4+ by Al3+ in the tetrahedral silicate layer

  6. Polyaniline-sodium montmorillonite clay nanocomposites: effect of clay concentration on thermal, structural, and electrical properties

    Czech Academy of Sciences Publication Activity Database

    Kazim, Samrana; Ahmad, S.; Pfleger, Jiří; Pleštil, Josef; Joshi, Y. M.

    2012-01-01

    Roč. 47, č. 1 (2012), s. 420-428 ISSN 0022-2461 R&D Projects: GA MŠk 7E10040 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyaniline * conductive polymer * montmorillonite Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.163, year: 2012

  7. Adsorption capacity of methylene blue, an organic pollutant, by montmorillonite clay

    KAUST Repository

    Feddal, I.; Ramdani, Amina; Taleb, Safia; Gaigneaux, E. M.; Batis, Narjè s Harrouch; Ghaffour, NorEddine

    2013-01-01

    The isotherms and kinetics of the adsorption of a cationic dye in aqueous solution, methylene blue, on a local Algerian montmorillonite clay mineral (raw, sodium and thermally activated at 300 and 500°C) were determined experimentally. Various parameters influencing the adsorption were optimized, mainly solid-liquid contact time, mass of adsorbent, initial concentration of dye, pH of the solution and temperature. Results showed that the adsorption kinetics were fast: 30 min for the raw clay mineral, and 20 min for sodium clay mineral (SC) and thermally activated at 300°C, whereas with the clay mineral calcined at 500°C, the equilibrium was reached after 150 min only. The maximum adsorption capacity was reached at pH 6.6. Results deducted from the adsorption isotherms also showed that the retention follows the Langmuir model. In addition, it was found that the kinetics were in the order of 2 (K = 2.457 × 106 g/mg.h) for sodium clay and were limited by an intra-particle diffusion. SC was found to be a better adsorbent to remove methylene blue from industrial wastewater. © 2013 Balaban Desalination Publications. All rights reserved.

  8. Adsorption capacity of methylene blue, an organic pollutant, by montmorillonite clay

    KAUST Repository

    Feddal, I.

    2013-11-19

    The isotherms and kinetics of the adsorption of a cationic dye in aqueous solution, methylene blue, on a local Algerian montmorillonite clay mineral (raw, sodium and thermally activated at 300 and 500°C) were determined experimentally. Various parameters influencing the adsorption were optimized, mainly solid-liquid contact time, mass of adsorbent, initial concentration of dye, pH of the solution and temperature. Results showed that the adsorption kinetics were fast: 30 min for the raw clay mineral, and 20 min for sodium clay mineral (SC) and thermally activated at 300°C, whereas with the clay mineral calcined at 500°C, the equilibrium was reached after 150 min only. The maximum adsorption capacity was reached at pH 6.6. Results deducted from the adsorption isotherms also showed that the retention follows the Langmuir model. In addition, it was found that the kinetics were in the order of 2 (K = 2.457 × 106 g/mg.h) for sodium clay and were limited by an intra-particle diffusion. SC was found to be a better adsorbent to remove methylene blue from industrial wastewater. © 2013 Balaban Desalination Publications. All rights reserved.

  9. Adhesion of the clay minerals montmorillonite, kaolinite, and attapulgite reduces respiration of Histoplasma capsulatum.

    Science.gov (United States)

    Lavie, S; Stotzky, G

    1986-01-01

    The respiration of three phenotypes of Histoplasma capsulatum, the causal agent of histoplasmosis in humans, was markedly reduced by low concentrations of montmorillonite but was reduced less by even higher concentrations of kaolinite or attapulgite (palygorskite). The reduction in respiration followed a pattern that suggested saturation-type kinetics: an initial sharp reduction that occurred with low concentrations of clay (0.01 to 0.5% [wt/vol]), followed by a more gradual reduction with higher concentrations (1 to 8%). Increases in viscosity (which could impair the movement of O2) caused by the clays were not responsible for the reduction in respiration, and the clays did not interfere with the availability of nutrients. Scanning electron microscopy after extensive washing showed that the clay particles were tightly bound to the hyphae, suggesting that the clays reduced the rate of respiration of H. capsulatum by adhering to the mycelial surface and, thereby, interfered with the movement of nutrients, metabolites, and gases across the mycelial wall.

  10. Moisture Absorption Behaviour of Biopolymer Polycapralactone (PCL) / Organo Modified Montmorillonite Clay (OMMT) biocomposite films

    Science.gov (United States)

    Malik, Neetu; Shrivastava, Sharad; Bandhu Ghosh, Subrata

    2018-04-01

    Bio composite materials were fabricated using mixing biodegradable polymer polycaptalactone (PCL) and Organo Modified Montmorillonite Clay (OMMT) through solution casting. Various samples of bio composite films were prepared by varying the OMMT wt% composition by 0.1%, 0.5%, 1% and 1.5%. Thereafter, the density and water absorption of the composites were investigated with respect to immersion time in water. The moisture absorption results show that with an increase in weight percentage (from 0.1 to wt 1.5%) of OMMT within the bio polymer films, the absorption value of bio-nanocomposite films reduced rapidly from 34.4% to 22.3%. The density of hybrid composites also increased with increase in weight percentage of OMMT. The swelling characteristic of PCL increased with increasing % of OMMT clay. These results indicate that the optimized composition of constituents in composite membrane could effectively reduce the anhydrous conditions of bio-composite film.

  11. Preparation of nanocomposites polyurethane water bone with clay montmorillonite sodica and organophilic clay

    International Nuclear Information System (INIS)

    Garcia, Claudia P.; Delpech, Marcia C.; Coutinho, Fernanda M.B.; Mello, Ivana L.

    2009-01-01

    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)

  12. Comparative evaluation between montmorillonite clay/LLDPE and potassium hexaniobate/LLDPE nanocomposites: characterization of mechanical and transport properties

    International Nuclear Information System (INIS)

    Komatsu, Daniel; Otaguro, Harumi; Ruvolo Filho, Adhemar C.

    2014-01-01

    Linear low density polyethylene-montmorillonite clay and linear low density polyethylene-organophilic niobate nanocomposites were obtained from dilution of masterbatch with 20% w/w of fillers in the LLDPE matrix by melt intercalation using a twin-screw extruder, obtaining nanocomposites with 1.5% up to 10.0% w/w of filler. In this study mechanical and water vapor and oxygen permeation tests were used to characterize the nanocomposites. In mechanical tests an increase of modulus values and decrease of toughness value by increasing concentration of montmorillonite clay were observed. The behavior of LLDPE-organophilic niobate nanocomposites was similar to LLDPE-montmorillonite clay nanocomposites but softer due to hexaniobate structure. The distribution of the organoclay is more homogeneous than organophilic niobate to concentrations below 10.0% filler using the SEM/FEG. It is possible to see a decrease in the permeability value with increasing concentration of montmorillonite clay for both gases used. In the LLDPE-organophilic niobate nanocomposites a decrease of permeability value occurs followed by an increase of permeability value for both gases used, with increasing concentration of organophilic niobate. Furthermore, it was observed that the polarity of the gas used is an important factor in the diffusion process through the nanocomposite. (author)

  13. Nanostructure and thermal properties of melt compounded PE/clay nanocomposites filled with an organosilylated montmorillonite

    International Nuclear Information System (INIS)

    Scarfato, Paola; Incarnato, Loredana; Di Maio, Luciano; Dittrich, Bettina; Niebergall, Ute; Böhning, Martin; Schartel, Bernhard

    2015-01-01

    In this work we report on the functionalization of a natural sodium montmorillonite (MMT) with (3-glycidyloxypropyl)trimethoxysilane by a silylation procedure and on its use as nanofiller in melt compounding of polyethylene nanocomposites. The obtained organosilylated clay showed higher interlayer spacing than the original MMT and higher thermal stability with respect to most of commercial organoclays modified with alkylammonium salts. Its addition (at 5wt%) to two different polyethylene matrices (a low density polyethylene, LDPE, and a high density polyethylene, HDPE), processed in a pilot-scale twin-screw extruder, allowed to produce hybrids with nanoscale dispersion of the filler, as demonstrated by X-ray diffraction. Thermogravimetric and differential scanning thermal analyses point out that the obtained nanocomposites do not show noticeable changes in the thermal behavior of both LDPE and HDPE, even if a slight reduction in the overall bulk crystallinity was observed in presence of the nanofillers

  14. Nanostructure and thermal properties of melt compounded PE/clay nanocomposites filled with an organosilylated montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Scarfato, Paola, E-mail: pscarfato@unisa.it [Department of Industrial Engineering, University of Salerno Via Giovanni Paolo II 132 – 84084 Fisciano (Italy); BAM - Federal Institute for Materials Research and Testing, 7.5 Technical Properties of Polymeric Materials, Unter den Eichen 87 - 12205 Berlin (Germany); Incarnato, Loredana; Di Maio, Luciano [Department of Industrial Engineering, University of Salerno Via Giovanni Paolo II 132 – 84084 Fisciano (Italy); Dittrich, Bettina; Niebergall, Ute; Böhning, Martin; Schartel, Bernhard [BAM - Federal Institute for Materials Research and Testing, 7.5 Technical Properties of Polymeric Materials, Unter den Eichen 87 - 12205 Berlin (Germany)

    2015-12-17

    In this work we report on the functionalization of a natural sodium montmorillonite (MMT) with (3-glycidyloxypropyl)trimethoxysilane by a silylation procedure and on its use as nanofiller in melt compounding of polyethylene nanocomposites. The obtained organosilylated clay showed higher interlayer spacing than the original MMT and higher thermal stability with respect to most of commercial organoclays modified with alkylammonium salts. Its addition (at 5wt%) to two different polyethylene matrices (a low density polyethylene, LDPE, and a high density polyethylene, HDPE), processed in a pilot-scale twin-screw extruder, allowed to produce hybrids with nanoscale dispersion of the filler, as demonstrated by X-ray diffraction. Thermogravimetric and differential scanning thermal analyses point out that the obtained nanocomposites do not show noticeable changes in the thermal behavior of both LDPE and HDPE, even if a slight reduction in the overall bulk crystallinity was observed in presence of the nanofillers.

  15. Aromatic-aliphatic polyamide/montmorillonite clay nanocomposite materials: Synthesis, nanostructure and properties

    International Nuclear Information System (INIS)

    Zulfiqar, Sonia; Ahmad, Zahoor; Ishaq, Muhammad; Sarwar, Muhammad Ilyas

    2009-01-01

    New type of aromatic-aliphatic polyamide/montmorillonite nanocomposites were produced using solution intercalation technique in dimethylacetamide. The modification of clay was carried out with ammonium salt of long chain alkyl amine. The nanocomposites were probed for organoclay dispersion, mechanical, thermal and water absorption measurements. Formation of delaminated and intercalated nanostructures was confirmed by X-ray diffraction and TEM studies. Improvement in tensile strength and modulus was observed for nanocomposites with optimum organoclay content (8-wt.%). Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. Differential scanning calorimetric results revealed increase in glass transition temperatures (T g ) with augmenting organoclay in the nanocomposites. Water uptake of the nanocomposites reduced than the neat polyamide rendering decreased permeability.

  16. Aromatic-aliphatic polyamide/montmorillonite clay nanocomposite materials: Synthesis, nanostructure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Zulfiqar, Sonia [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Ahmad, Zahoor [Department of Chemistry, Faculty of Science, Kuwait University, P. O. Box: 5969, Safat 13060 (Kuwait); Ishaq, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Sarwar, Muhammad Ilyas, E-mail: ilyassarwar@hotmail.com [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716 (United States)

    2009-11-15

    New type of aromatic-aliphatic polyamide/montmorillonite nanocomposites were produced using solution intercalation technique in dimethylacetamide. The modification of clay was carried out with ammonium salt of long chain alkyl amine. The nanocomposites were probed for organoclay dispersion, mechanical, thermal and water absorption measurements. Formation of delaminated and intercalated nanostructures was confirmed by X-ray diffraction and TEM studies. Improvement in tensile strength and modulus was observed for nanocomposites with optimum organoclay content (8-wt.%). Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. Differential scanning calorimetric results revealed increase in glass transition temperatures (T{sub g}) with augmenting organoclay in the nanocomposites. Water uptake of the nanocomposites reduced than the neat polyamide rendering decreased permeability.

  17. 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. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Iron-montmorillonite clays as active sorbents for the decontamination of hazardous chemical warfare agents.

    Science.gov (United States)

    Carniato, F; Bisio, C; Evangelisti, C; Psaro, R; Dal Santo, V; Costenaro, D; Marchese, L; Guidotti, M

    2018-02-27

    A class of heterogeneous catalysts based on commercial bentonite from natural origin, containing at least 80 wt% of montmorillonite clay, was designed to transform selectively and under mild conditions toxic organosulfur and organophosphorus chemical warfare agents into non-noxious products with a reduced impact on health and environment. The bentonite from the natural origin was modified by introducing iron species and acid sites in the interlayer space, aiming to obtain a sorbent with strong catalytic oxidising and hydrolytic properties. The catalytic performance of these materials was evaluated in the oxidative abatement of (2-chloroethyl)ethyl sulfide (CEES), a simulant of sulfur mustard, in the presence of aqueous hydrogen peroxide as an oxidant. A new decontamination formulation was, moreover, proposed and obtained by mixing sodium perborate, as a solid oxidant, to iron-bentonite catalysts. Solid-phase decontamination tests, performed on a cotton textile support contaminated with organosulfide and organophosphonate simulant agents revealed the good activity of the solid formulation, especially in the in situ detoxification of blistering agents. Tests carried out on the real blistering warfare agent, sulfur mustard (HD agent), showed that, thanks to the co-presence of the iron-based clay together with the solid oxidant component, a good decontamination of the test surface from the real warfare agent could be achieved (80% contaminant degradation, under ambient conditions, in 24 h).

  19. Synthesis and characterization of a PbO2-clay nanocomposite: Removal of lead from water using montmorillonite

    International Nuclear Information System (INIS)

    Aroui, L.; Zerroual, L.; Boutahala, M.

    2012-01-01

    Graphical abstract: The replacement of Na by Pb in the interlayer space of the smectite leads to a decrease in the intensity of the the (0 0 1) reflection as the concentration of lead nitrate increases. A significant restructuring at the particle scale is observed leading probably to the exfoliation of the caly. In addition, the thermal behaviour of the montmorillonite samples with regard to their dehydration and dehydroxilation capacities is significantly influenced. This leads to a lowering of the water content and a decrease in the ionic conductivity of the clay. Highlights: ► In the clay, Pb replaces Na ions and a significant restructuring at the particle scale is observed. ► Pb influenced significantly the thermal behaviour of the clay with regard to its dehydration. ► In the interlayer space, the exchange of Na by Pb leads to a decrease in the protonic conductivity. ► A PbO 2 -clay nanocomposite material with good conductivity is synthesized. -- Abstract: The aim of this paper is to present the results obtained with Pb(II) sorption on an Algerian Clay. The experiments were carried out using a batch process. Powder X-rays diffraction patterns (PXRD) prove that in the montmorillonite Pb replaces Na ions. A significant restructuring at the particle scale is observed leading to the disappearance of the d 001 reflection of the clay at high concentrations of lead. The replacement of hydrated Na with Pb ions influenced significantly the thermal behaviour of the montmorillonite samples with regard to their dehydration and dehydroxilation capacities with a lowering of the water content. A PbO 2 -clay composite material with good electrical conductivity is synthesized.

  20. Nanocomposites based on epoxy resin and montmorillonite: effect of clay percent and dispersion state on thermomechanical properties

    International Nuclear Information System (INIS)

    Zaioncz, Soraia; Soares, Bluma G.

    2009-01-01

    Nanocomposites of epoxy resin modified with PMMA and montmorillonite organophilic were synthesized with clay content equal to 0.1, 1, 2.5, 5 and 7 (wt %). Dispersion state and the nano structure of materials has been investigated using small angle X-ray scattering (SAXS). The nanocomposites containing 0.1 (wt %) of clay showed an exfoliated morphology, while the nanocomposites with higher clay content (1 to 7 wt %) show that the dispersion state is less uniform and that large aggregates coexist with tactoids stacks of two or three platelets. The nano structure of materials was correlated with its thermomechanical properties obtained by DMTA. The results showed an increase in Tg of the materials to clay content of up to 5 wt % and an increase in the storage modulus for the epoxy matrix. (author)

  1. Estimating vertical and lateral pressures in periodically structured montmorillonite clay particles

    Directory of Open Access Journals (Sweden)

    Guillermo A. Narsilio

    2010-03-01

    Full Text Available Given a montmorillonitic clay soil at high porosity and saturated by monovalent counterions, we investigate the particle level responses of the clay to different external loadings. As analytical solutions are not possible for complex arrangements of particles, we employ computational micromechanical models (based on the solution of the Poisson-Nernst-Planck equations using the finite element method, to estimate counterion and electrical potential distributions for particles at various angles and distances from one another. We then calculate the disjoining pressures using the Van't Hoff relation and Maxwell stress tensor. As the distance between the clay particles decreases and double-layers overlap, the concentration of counterions in the micropores among clay particles increases. This increase lowers the chemical potential of the pore fluid and creates a chemical potential gradient in the solvent that generates the socalled 'disjoining' or 'osmotic' pressure. Because of this disjoining pressure, particles do not need to contact one another in order to carry an 'effective stress'. This work may lead towards theoretical predictions of the macroscopic load deformation response of montmorillonitic soils based on micromechanical modelling of particles.Dada uma argila montmorilonítica de alta porosidade e saturada por counteríons monovalentes, investigamos as respostas da argila ao nível de partículas para diferentes cargas externas. Como soluções analíticas não são possíveis para arranjos complexos de partículas, empregamos modelos computacionais micro-mecânicos (baseados na solução das equações de Poisson-Nernst-Planck, utilizando o método de elementos finitos, para estimar counteríons e distribuições de potencial elétrico para partículas em diversos ângulos e distâncias uma da outra. Nós então calculamos as pressões de separação usando a relação de Van't Hoff e a tensão de cisalhamento de Maxwell. À medida que a

  2. The synthesis and application of pillared clays prepared from charge reduced montmorillonite

    Science.gov (United States)

    Engwall, Erik Edwin

    The synthesis of pillared interlayered clays (PILCs) makes use of the cation exchange capacity (CEC) of clay minerals to prop their structures open with large hydroxy-metal cations. Homo-ionic Ca-Montmorillonite with a CEC of 83.9 meq/100 g has been partially exchanged with varied amounts of Li+ and heated to 200°C for 24 hours. These have been used to produce Zr and Al PILCs making use of ethanol/water synthesis solutions to overcome the hydrophobic nature of the clay. For the Zr-PILC system, the d(001) spacings determined by x-ray diffraction (XRD) were relatively constant at 19.0--20.1 A with respect to changing the unpillared CEC. The Zr-PILCs had type I isotherms for argon at 87 K and for benzene, p-xylene and 1,3,5-trimethylbenzene adsorption at 30°C. Several Al-PILC synthesis procedures were evaluated and all produced materials whose adsorption capacity decreased with decreasing unpillared CEC. This reduction in adsorption capacity with unpillared CEC could be partially overcome by the combined use of ethanol/water pillaring solutions with ethanol/water washing. Previously unreported d(001) values in the range of 26.8 to 29.8 A were observed in Al-PILCs and were often bimodal with the expected values of about 18 A. These larger d(001) values were most prevalent at lower CEC values, if pillaring conditions favored the formation of polymeric species other than the Keggin cation. A new micropore size distribution model was developed to better understand PILC pore structure. The new model was compared to the Horvath and Kawazoe (1983) model (HK) and the Cheng and Yang (1994) model (CY) using argon adsorption at 87 K on Zr and Al-PILCs. The interlayer spacings determined by XRD for the test PILCs were 9.5 and 8.5 A for Zr and Al-PILCs respectively. Pore sizes predicted by the new model were 7.5 and 7.3 A for Zr and Al-PILCs respectively. The new model consistently predicts values that are closer to the interlayer spacing than either the HK or CY models. The new

  3. Fixation of enzyme protein in soil by the clay mineral montmorillonite

    DEFF Research Database (Denmark)

    Sørensen, L.H.

    1969-01-01

    Aminosäureverbindungen, die im Boden während des biologischen Abbaus von Kohlehydraten gebildet und vom Tonmineral Montmorillonit stabilisiert werden, haben Enzymcharakter und sind folglich Proteine.......Aminosäureverbindungen, die im Boden während des biologischen Abbaus von Kohlehydraten gebildet und vom Tonmineral Montmorillonit stabilisiert werden, haben Enzymcharakter und sind folglich Proteine....

  4. An electrospun nanofiber matrix based on organo-clay for biosensors: PVA/PAMAM-Montmorillonite

    Science.gov (United States)

    Unal, Betul; Yalcinkaya, Esra Evrim; Demirkol, Dilek Odaci; Timur, Suna

    2018-06-01

    Diagnostic techniques based on biomolecules have huge a potential to be applied in the application in various areas such as food/beverage industries, diseases diagnostics, monitoring of bio-processes and environmental pollutants. Immobilization of biomolecules on a transducer is the key parameter to being able to prepare a highly stable diagnostic tests. Electrospun nanofibers are a good alternative to immobilize biomolecules. Here, electrospun nanofibers based on an organoclay were used to design the first generation amperometric enzyme biosensor. PAMAM G2 dendrimers were used to intercalate montmorillonite clay (Mt) and then the modification of Mt by PAMAM was characterized using FTIR, XRD, TGA and zeta potential measurements. After that nanofibers were prepared by electrospinning Mt and PAMAM-Mt using poly(vinyl) alcohol (PVA) as an auxiliary polymer and the formed PVA/PAMAM-Mt electrospun nanofibers were proved by SEM, TEM and AFM techniques. Finally, pyranose oxidases (PyOx) were immobilized on a glassy carbon electrode surface, which was modified using the PVA/PAMAM-Mt electrospun nanofibers. Amperometric measurements were carried out using buffer solution at -0.7 V under stirring conditions. The linear response for glucose was from 0.005 mM to 0.25 mM using PVA/Mt/PyOx and PVA/PAMAM-Mt/PyOx biosensors. The limit of detection was 0.7 μM glucose with PVA/PAMAM-Mt/PyOx biosensor. To detect glucose in real sample, measurements were carried out using soft drink cola as a substrate instead of glucose.

  5. Nanocomposites of polypropylene and organophilic montmorillonite clay: X-ray diffraction, infrared spectroscopy with Fourier transform and water permeation

    International Nuclear Information System (INIS)

    Morelli, Fernanda C.; Ruvolo Filho, Adhemar

    2009-01-01

    In this work were prepared nanocomposites of polypropylene and organophilic montmorillonite Cloisite 20A with concentrations of 1.5%, 2.5%, 5.0% and 7.5% clay and graft polypropylene with maleic anhydride as compatibilizer. The mixture was made in the melt state using a twin screw extruder. The materials were characterized by x-ray diffraction, infrared spectroscopy with Fourier transform and analysis of water vapor permeation. The results of x-ray diffraction and infrared spectroscopy indicates the formation of nanocomposites with structures probably exfoliate and / or intercalated for concentrations of 1.5% and 2.5% clay, and provided a marked decrease in the water permeability, corroborating with other analysis. (author)

  6. A curcumin activated carboxymethyl cellulose-montmorillonite clay nanocomposite having enhanced curcumin release in aqueous media.

    Science.gov (United States)

    Madusanka, Nadeesh; de Silva, K M Nalin; Amaratunga, Gehan

    2015-12-10

    A novel curcumin activated carboxymethylcellulose-montmorillonite nanocomposite is reported. A superabsorbent biopolymer; carboxymethyl cellulose (CMC) was used as an emulsifier for curcumin which is a turmeric derived water insoluble polyphenolic compound with antibacterial/anti-cancer properties. Montmorillonite (MMT) nanoclay was incorporated in the formulation as a matrix material which also plays a role in release kinetics. It was observed that water solubility of curcumin in the nanocomposite has significantly increased (60% release within 2h and 30 min in distilled water at pH 5.4) compared to pure curcumin. The prepared curcumin activated carboxymethylcellulose-montmorillonite nanocomposite is suitable as a curcumin carrier having enhanced release and structural properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2002-07-01

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

  8. Cu2+ Montmorillonite K10 Clay Catalyst as a Green Catalyst for Production of Stearic Acid Methyl Ester: Optimization Using Response Surface Methodology (RSM)

    OpenAIRE

    Enas A. Almadani; Farah W. Harun; Salina M. Radzi; Syamsul K. Muhamad

    2018-01-01

    Clay catalyst has received much attention to replace the homogeneous catalysts in the esterification reaction to produce fatty acid methyl ester as the source of biodiesel as it is low cost, easily available, as well as environmental friendly. However, the use of unmodified clay, in particular montmorillonite K10 (MMT K10), for the esterification of fatty acids showed that the acid conversion was less than 60% and this is not preferable to the production of biodiesel. In this study, synthesis...

  9. Effect of montmorillonite clay addition on the morphological and physical properties of Jatropha curcas L. and Glycine max L. protein concentrate films

    Science.gov (United States)

    Protein concentrates from jatropha (JPC) and soy seeds (SPC) were obtained by solubilization and acid precipitation of proteins. Films from JPC and SPC were prepared by the casting method, using two different montmorillonite (MMT) clay concentrations and plasticized with glycerol. Film properties we...

  10. Mechanism of smectic arrangement of montmorillonite and bentonite clay platelets incorporated in gels of poly(acrylamide) induced by the interaction with cationic surfactants.

    Science.gov (United States)

    Starodoubtsev, S G; Lavrentyeva, E K; Khokhlov, A R; Allegra, G; Famulari, A; Meille, S V

    2006-01-03

    Structure transitions, induced by the interaction with the cationic surfactant cetylpyridinium chloride in nanocomposite gels of poly(acrylamide) with incorporated suspensions of the two closely related layered clays bentonite and montmorillonite, were studied. Unexpectedly, different behaviors were revealed. X-ray diffraction measurements confirm that, due to the interaction with the surfactant, initially disordered bentonite platelets arrange into highly ordered structures incorporating alternating clay platelets and surfactant bilayers. The formation of these smectic structures also in the cross-linked polymer gels, upon addition of the surfactant, is explained by the existence of preformed, poorly ordered aggregates of the clay platelets in the suspensions before the gel formation. In the case of montmorillonite, smectic ordering of the disordered platelets in the presence of the surfactant is observed only after drying the suspensions and the clay-gel composites. Rheology studies of aqueous suspensions of the two clays, in the absence of both surfactant and gel, evidence a much higher viscosity for bentonite than for montmorillonite, suggesting smaller clay-aggregate size in the latter case. Qualitatively consistent results are obtained from optical micrographs.

  11. Wheat gluten/montmorillonite biocomposites: Effect of pH on the mechanical properties and clay dispersion

    Directory of Open Access Journals (Sweden)

    E. Cortes-Trivino

    2018-07-01

    Full Text Available The addition of inorganic fillers into a bioplastic could increase its mechanical properties, which will be influenced strongly by the type of the clay dispersion. In this work, we have used montmorillonite nanoclays (MMT to prepare biocomposites by means of an extrusion process. We present herein the effect of the pH and the addition of montmorillonite nanoclays (MMT on the barrier and mechanical properties of wheat gluten based bioplastics. The pH of the samples was modified by adding aqueous solution of a strong acid or base (H2SO4 and NaOH. Tensile, dynamic mechanical thermal analysis (DMTA, water absorption and X-ray tests were carried out to study the influence of the above-mentioned variables on the physicochemical properties and rheological behaviour of bioplastics and biocomposites obtained. Tensile results showed that both Young’s modulus and tensile strength are higher at unmodified pH. However, the addition of MMT to an alkaline biopolymer matrix produced remarkable improvements in the rheological and mechanical properties because of a high exfoliation of the nanoclay noticeable in X-ray results. To summarise, extrusion process and the use of nanoclays present an excellent opportunity to develop wheat gluten bioplastics able to replace conventional products.

  12. Intranasal inoculation of white-tailed deer (Odocoileus virginianus with lyophilized chronic wasting disease prion particulate complexed to montmorillonite clay.

    Directory of Open Access Journals (Sweden)

    Tracy A Nichols

    Full Text Available Chronic wasting disease (CWD, the only known prion disease endemic in wildlife, is a persistent problem in both wild and captive North American cervid populations. This disease continues to spread and cases are found in new areas each year. Indirect transmission can occur via the environment and is thought to occur by the oral and/or intranasal route. Oral transmission has been experimentally demonstrated and although intranasal transmission has been postulated, it has not been tested in a natural host until recently. Prions have been shown to adsorb strongly to clay particles and upon oral inoculation the prion/clay combination exhibits increased infectivity in rodent models. Deer and elk undoubtedly and chronically inhale dust particles routinely while living in the landscape while foraging and rutting. We therefore hypothesized that dust represents a viable vehicle for intranasal CWD prion exposure. To test this hypothesis, CWD-positive brain homogenate was mixed with montmorillonite clay (Mte, lyophilized, pulverized and inoculated intranasally into white-tailed deer once a week for 6 weeks. Deer were euthanized at 95, 105, 120 and 175 days post final inoculation and tissues examined for CWD-associated prion proteins by immunohistochemistry. Our results demonstrate that CWD can be efficiently transmitted utilizing Mte particles as a prion carrier and intranasal exposure.

  13. Dynamics of water and ions in clays of type montmorillonite by microscopic simulation and quasi-elastic neutron scattering

    International Nuclear Information System (INIS)

    Malikova, N.

    2005-09-01

    Montmorillonite clays in low hydration states, with Na + and Cs + compensating counter ions, are investigated by a combination of microscopic simulation and quasi-elastic neutron scattering to obtain information on the local structure and dynamics of water and ions in the interlayer. At first predictions of simulation into the dynamics of water and ions at elevate temperatures are shown (0 deg C 80 deg C, pertinent for the radioactive waste disposal scenario) Marked difference is observed between the modes of diffusion of the Na + and C + counter ions. In water dynamics, a significant step towards bulk water behaviour is seen on transition from the mono- to bilayer states. Secondly, a detailed comparison between simulation and quasi-elastic neutron scattering (Neutron Spin Echo and Time-of-Flight) regarding ambient temperature water dynamics is presented. Overall, the approaches are found to be in good agreement with each other and limitations of each of the methods are clearly shown. (author)

  14. Montmorillonite clay/polypropylene (HMSPP) nanocomposites: evaluation of thermal and mechanical properties

    International Nuclear Information System (INIS)

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

    2014-01-01

    The evaluation of HMSPP (high melt strength polypropylene) properties in nanocomposites was done in composites of 0.1; 1; 3; 5; 10 wt% of Cloisite 20A clay. The PP-g-MA (polypropylene graft maleic anhydride) was the compatibilizer agent in the process of extrusion in twin-screw. Mechanical tests performed in the nanocomposites with higher clay content showed higher values of rupture in 5 and 10 wt% of Cloisite. The thermal properties were evaluate utilizing Calorimetry Differential Exploratory (DSC) and in the sample of 10 wt% of Cloisite were observed increase of the melting temperature and increase of crystallinity. The morphology was investigated by the Scanning Electron Microscopy (SEM) and Fourier Transformed Infrared (FTIR), in which the sample with lower clay amount, 1 wt% of Cloisite showed better dispersion of the clay. X-Ray Diffraction reported the clay intercalation in the sample with 5 wt% of clay. (author)

  15. Layer-by-layer composite film of nickel phthalocyanine and montmorillonite clay for synergistic effect on electrochemical detection of dopamine

    Science.gov (United States)

    de Lucena, Nathalia C.; Miyazaki, Celina M.; Shimizu, Flávio M.; Constantino, Carlos J. L.; Ferreira, Marystela

    2018-04-01

    Dopamine (DA) abnormal levels are related to diseases which makes important the development of fast, reliable, low-cost and sensitive devices for diagnosis and pharmaceutical controls. Nanostructured film composite of sodium montmorillonite clay (Na+MMT) and nickel phthalocyanine (NiTsPc) was self-assembled by layer-by-layer (LbL) technique and applied as electrochemical sensor for DA in the presence of common natural interferents as ascorbic acid (AA) and uric acid (UA). Three different LbL architecture films were investigated: LbL films of clay (PEI/Na+MMT) and phthalocyanine (PEI/NiTsPc) in a bilayer structure with a conventional polyelectrolyte (PEI) and a composite film formed by both materials to verify the synergistic effect in the LbL film in a quadri-layer assembly (PEI/Na+MMT/PEI/NiTsPc). Structural characterization indicated molecular level interactions between the layers forming the LbL films. The ITO/(PEI/Na+MMT/PEI/NiTsPc)10 electrode exhibited a LOD of 1.0 μmol L-1 and linear range 5-150 μmol L-1.

  16. Investigation of adsorption of the dyestuff astrazon red violet 3rn (basic violet 16 on montmorillonite clay

    Directory of Open Access Journals (Sweden)

    B. A. Fil

    2014-03-01

    Full Text Available In this study, color removal by absorption from synthetically prepared wastewater was investigated using montmorillonite clay by adsorption. As dyestuff Astrazon Red Violet 3RN (Basic Violet 16 was used. Experimental parameters selected were pH, temperature, agitation speed, initial dyestuff concentration, adsorbent dosage and ionic strength. It was established that adsorption rate increased with increasing pH, temperature, dye concentration and agitation speed, but decreased with increased ionic strength and adsorbent dosage. Adsorption equilibrium data obtained by a series of experiments carried out in a water bath were employed with common isotherm equations such as Langmuir, Freundlich, Temkin, Elovich and Dubinin-Radushkevich. It was found that the Langmuir equation appears to fit the equilibrium data better than the other models. Furthermore, the fit of the kinetic data to common kinetic models such as the pseudo-first-order, second-order, Elovich and intraparticle diffusion models was tested to elucidate the adsorption mechanism. Kinetic data conformed to the pseudo-second-order model, indicating chemisorptions. In addition, the thermodynamic parameters activation energy, Ea, enthalpy ΔH*, entropy, ΔS*, and free energy change, ΔG*, were calculated. The values of the calculated parameters indicated that physical adsorption of ARV on the clay was dominant and that the adsorption process was endothermic.

  17. Modification and characterization of montmorillonite clay for the extraction of zearalenone

    Science.gov (United States)

    Hue, Kerri-Ann Alicia

    Mycotoxins are secondary metabolites of organisms belonging to the fungus kingdom. The cost associated with mycotoxin contamination in the USA and Canada is approximately US $5 billion. Zearalenone (ZEN), a resorcylic acid lactone, is produced by various members of the genus Fusarium . These fungi often colonize a variety of foods and feedstuffs including, corn, sorghum, wheat, oats, barley, and other cereal grains. This metabolite has estrogenic effects in farm animals with pigs being the most sensitive. ZEN induces hyperestrogenism and can cause infertility, reduced sex drive, fetal mummification, and abortions. Clays have successfully been used in the animal feed industry as an adsorbent and binders for certain small, water soluble mycotoxins. These mycotoxins are attracted to the electrical imbalance between the layers of the clays caused by isomorphic substitution of structural atoms. The mycotoxins are sequestered in the clay layers and pass harmlessly through the animal. However, ZEN is water insoluble and is not extracted easily with aluminosilicate clays. Therefore the modification of hydrated sodium calcium aluminosilicate (HSCAS) clays with organic cations has been proposed to render the clays hydrophobic and increase the ZEN binding capacity. The goal of this study was to develop a safe and cost effective organophilic material able to bind and extract zearalenone, to investigate the factors most important to extraction, and to investigate the fundamental properties between the clay-surfactant-mycotoxin systems that lead to extraction. The clay was modified by cation exchange reactions with tricaprylmethylammonium (TCMA) chloride and generic corn oil. The organophilic clays were then characterized using XRD, FTIR, and TGA analytical techniques. These techniques were used to determine the change in fundamental clay properties that would lead to the extraction of ZEN. Desorption studies were performed to determine any increase in toxicity that might be

  18. Thermal Stability of Clay's Galleries in Polypropylene - Clay (montmorillonite Nanocomposites using Polypropylene-gMaleic Anhydride as Compatibilizer

    Directory of Open Access Journals (Sweden)

    Sotya Astutiningsih

    2010-10-01

    Full Text Available Superior properties of food packaging can be achieved using nanocomposite technology. However, fabrication of this materials are complex and expensive. Long term objectives of this research is the synthesis of low cost polypropylene clay nanocomposites (PPCN via a short-cut method known as ‘cascade engineering’. Cascade engineering principle in PPCN fabrication is performed by using compatibilizer (to enable the mixing of PP and clay masterbatch, and PPCN in one pot process using melt mixer. This paper present the experimental results using small-angle x-ray diffraction (XRD on the thermal stability of the PPCN. Results from the XRD analysis showed that the clay was intercalated, however no significant changes were observed as a result of variation in mixing time. XRD patterns of the annealed PPCN showed reduction of MMT’s gallery (deintercalation These phenomenon was probably caused by insufficient bonding and lack of compatibility between PP-g-MA and MMT.

  19. Effects of adding nano-clay (montmorillonite) on performance of polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives in Carapa guianensis, a tropical species

    OpenAIRE

    Rodríguez-Zúñiga, Ana; Vega-Baudrit, José; Alvarez, Vera; Moya-Roque, Roger

    2015-01-01

    http://www.scopus.com/inward/record.url?eid=2-s2.0-84923601829&partnerID=40&md5=5c91a6df9afec4f33b7be09b86735a75 The aim of this study was to improve the bond strength resistance of polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives modified with nano-clay (montmorillonite) with a tropical species of wood known to exhibit adhesion related problems. These adhesives were evaluated with 1.0 and 1.5 wt% nano-clay concentrations with lap shear strength (SS), and the percentage of woo...

  20. Morphology modification of polyethersulfone membrane from montmorillonite clay presence; Modificacao da morfologia de membrana de polietersulfona a partir da presenca de argila montmorilonita

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, R.S.B.; Oliveira, S.S.L.; Leite, A.M.D.; Araujo, E.M.; Lira, H.L., E-mail: edcleide.araujo@dema.ufcg.edu.br [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Universidade Federal do Rio Grande do Norte (ECT/UFRN), Natal, RN (Brazil). Escola de Ciencias e Tecnologia

    2016-07-01

    The objective of this work is to produce hollow fiber membranes of polyethersulfone from the formation of hybrids with montmorillonite national clay (3 and 5% Brasgel PA), with the intention of modifying the morphology and improving the flow properties of the PES membrane. Initially, flat membranes were produced for characterization by X-ray diffraction (XRD) and contact angle. By XRD it was evident that membrane production and clay influenced the crystallinity of the polymer. The measurement of the contact angle indicated that the incorporation of clay promoted a change in membrane hydrophilicity, being more evident for with the 3% of MMT. By means of scanning electron microscopy (SEM) it was evidenced that the clay modified the morphology of the membrane, having a better distribution of the pores and the 'fingers'. The flow measurements showed that the membrane containing 3% of MMT had a higher permeability to distilled water, indicating its potential for the treatment of liquid effluents. (author)

  1. Is montmorillonite-rich clay of MX-80 type the ideal buffer for isolation of HLW?

    International Nuclear Information System (INIS)

    Pusch, R.

    1999-12-01

    Four commercial clays, saponite, mixed-layer smectite-mica, kaolinite, and palygorskite, have been examined as possible alternatives to MX-80 buffer. General estimates based on the microstructural constitution and hydration potential as well as actual laboratory testing show that except for normally graded kaolinite, they would all serve acceptably in a repository. MX-80 is, however, superior with respect to hydraulic conductivity and retardation of diffusive transport of relevant cations and, like saponite and palygorskite, it has a high swelling pressure, that may in fact be too high. The mixed-layer clay is less but sufficiently expandable and is concluded to have better thermal and rheological properties as well as gas release capacity. It is hence the number one competitor to MX-80

  2. Is montmorillonite-rich clay of MX-80 type the ideal buffer for isolation of HLW?

    Energy Technology Data Exchange (ETDEWEB)

    Pusch, R [Geodevelopment AB, Lund (Sweden)

    1999-12-01

    Four commercial clays, saponite, mixed-layer smectite-mica, kaolinite, and palygorskite, have been examined as possible alternatives to MX-80 buffer. General estimates based on the microstructural constitution and hydration potential as well as actual laboratory testing show that except for normally graded kaolinite, they would all serve acceptably in a repository. MX-80 is, however, superior with respect to hydraulic conductivity and retardation of diffusive transport of relevant cations and, like saponite and palygorskite, it has a high swelling pressure, that may in fact be too high. The mixed-layer clay is less but sufficiently expandable and is concluded to have better thermal and rheological properties as well as gas release capacity. It is hence the number one competitor to MX-80.

  3. Structural evidence for the sorption of Ni(II) atoms on the edges of montmorillonite clay minerals: a polarized X-ray absorption fine structure study

    Science.gov (United States)

    Dähn, Rainer; Scheidegger, André M.; Manceau, Alain; Schlegel, Michel L.; Baeyens, Bart; Bradbury, Michael H.; Chateigner, Daniel

    The nature of surface complexes formed on Ni uptake onto montmorillonite (a dioctahedral smectite) has been investigated over an extended time period by polarized extended X-ray absorption fine structure (P-EXAFS) spectroscopy. Self-supporting films of Ni-sorbed montmorillonite were prepared by contacting Ni and montmorillonite at pH 7.2, high ionic strength (0.3 M NaClO 4), and low Ni concentration ([Ni] initial = 19.9 μM) for 14- and 360-d reaction time. The resulting Ni concentration on the clay varied from 4 to 7 μmol/g. Quantitative texture analysis indicates that the montmorillonite particles were well orientated with respect to the plane of the film. The full width at half maximum of the orientation distribution of the c* axes of individual clay platelets about the normal to the film plane was 44.3° (14-d reaction time) and 47.1° (360-d reaction time). These values were used to correct the coordination numbers determined by P-EXAFS for texture effects. Ni K-edge P-EXAFS spectra were recorded at angles between the incident beam and the film normal equal to 10, 35, 55, and 80°. Spectral analysis led to the identification of three nearest cationic subshells containing 2.0 ± 0.5 Al at 3.0 Å and 2.0 ± 0.5 Si at 3.12 Å and 4.0 ± 0.5 Si at 3.26 Å. These distances are characteristic of edge-sharing linkages between Al and Ni octahedra and of corner-sharing linkages between Ni octahedra and Si tetrahedra, as in clay structures. The angular dependence of the Ni-Al and Ni-Si contributions indicates that Ni-Al pairs are oriented parallel to the film plane, whereas Ni-Si pairs are not. The study reveals the formation of Ni inner-sphere mononuclear surface complexes located at the edges of montmorillonite platelets and thus that heavy metals binding to edge sites is a possible sorption mechanism for dioctahedral smectites. Data analysis further suggests that either the number of neighboring Al atoms slightly increases from 1.6 to 2 or that the structural order

  4. Nano-clays from natural and modified montmorillonite with and without added blueberry extract for active and intelligent food nanopackaging materials

    Energy Technology Data Exchange (ETDEWEB)

    Gutiérrez, Tomy J., E-mail: tomy.gutierrez@ciens.ucv.ve [Departamento Químico Analítico, Facultad de Farmacia, Universidad Central de Venezuela, Apartado 40109, Caracas, 1040-A (Venezuela, Bolivarian Republic of); Instituto de Ciencia y Tecnología de Alimentos, Facultad de Ciencias, Universidad Central de Venezuela, Apartado 47097, Caracas, 1041-A (Venezuela, Bolivarian Republic of); Grupo de Materiales Compuestos Termoplásticos (CoMP), Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA), Facultad de Ingeniería, Universidad Nacional de Mar del Plata UNMdP y Consejo Nacional de Investigaciones Científicas y Técnicas - CONICET, Colón 10850, B7608FLC, Mar del Plata (Argentina); Ponce, Alejandra G. [Grupo de Investigación en Ingeniería en Alimentos, Facultad de Ingeniería, Universidad Nacional de Mar del Plata (UNMdP), Juan B. Justo 4302, 7600, Mar del Plata (Argentina); Alvarez, Vera A. [Grupo de Materiales Compuestos Termoplásticos (CoMP), Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA), Facultad de Ingeniería, Universidad Nacional de Mar del Plata UNMdP y Consejo Nacional de Investigaciones Científicas y Técnicas - CONICET, Colón 10850, B7608FLC, Mar del Plata (Argentina)

    2017-06-15

    The aim of this study was to evaluate the potential of nano-clays as active and intelligent (A&I) food nanopackaging materials. Nanopackaging is a structured system that allows the storage of certain compounds in a stable form. Nano-clays were prepared from natural and modified montmorillonite (Mnt) with and without added blueberry extract, and characterized in terms of their: X-ray diffraction (XRD) patterns, thermogravimetric (TGA) properties, microstructure, moisture content, water activity (a{sub w}), infrared spectra (FTIR), Raman spectra, color parameters, response to pH changes, and antioxidant and antimicrobial activity. Mnt prepared with added blueberry extract showed antioxidant activity and intelligent behavior under different pH conditions. Modifying the Mnt increased the interlayer spacing, thus allowing more blueberry extract to be incorporated within the system. In conclusion, natural and modified Mnt are eco-friendly resources with potential applications for nano-packaging. The addition of blueberry extract imparted intelligent properties to the nano-clays as regards their responses to changes in pH. - Highlights: • Food nano-packaging were obtained from natural and modified montmorillonite (Mnt). • XRD, TGA and FTIR results suggests the blueberry extract nano-packaging. • Intelligent nanocomposites were obtained. • Greater interlayer spacing of the nano-Mnt allows greater nano-packaging.

  5. Nano-clays from natural and modified montmorillonite with and without added blueberry extract for active and intelligent food nanopackaging materials

    International Nuclear Information System (INIS)

    Gutiérrez, Tomy J.; Ponce, Alejandra G.; Alvarez, Vera A.

    2017-01-01

    The aim of this study was to evaluate the potential of nano-clays as active and intelligent (A&I) food nanopackaging materials. Nanopackaging is a structured system that allows the storage of certain compounds in a stable form. Nano-clays were prepared from natural and modified montmorillonite (Mnt) with and without added blueberry extract, and characterized in terms of their: X-ray diffraction (XRD) patterns, thermogravimetric (TGA) properties, microstructure, moisture content, water activity (a_w), infrared spectra (FTIR), Raman spectra, color parameters, response to pH changes, and antioxidant and antimicrobial activity. Mnt prepared with added blueberry extract showed antioxidant activity and intelligent behavior under different pH conditions. Modifying the Mnt increased the interlayer spacing, thus allowing more blueberry extract to be incorporated within the system. In conclusion, natural and modified Mnt are eco-friendly resources with potential applications for nano-packaging. The addition of blueberry extract imparted intelligent properties to the nano-clays as regards their responses to changes in pH. - Highlights: • Food nano-packaging were obtained from natural and modified montmorillonite (Mnt). • XRD, TGA and FTIR results suggests the blueberry extract nano-packaging. • Intelligent nanocomposites were obtained. • Greater interlayer spacing of the nano-Mnt allows greater nano-packaging.

  6. Characterized and cleaning process of montmorillonite clay from Parelhas, Rio Grande do Norte state, Brazil; Caracterizacao e processo de purificacao de argila montmorilonitica da cidade de Parelhas, RN, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Melo, G N; Costa, T C C; Paskocimas, C A [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2010-07-01

    The application of montmorillonite nano composites has been improved in order to obtain dispersed phase with particles of nano metric dimensions. To obtain these nanoparticles, the clays must pass an effective purification process for removing unwanted materials, which would undermine the processes of intercalation and exfoliation of montmorillonite in a polymer matrix. This study intention to characterize and purify a montmorillonite clay from deposit recently discovered in the city of Parelhas in Rio Grande do Norte, through the separation of coarser materials by decantation followed by a chemical attack that promoted oxidation in samples where it was realized reduction of impurities such as organic matter and other substances that would hinder the achievement of nanoparticles. Under these conditions, the clay is suitable for the work as dispersed phase in a polymer matrix nano composite. The results were demonstrated by analysis of scanning electron microscopy (SEM), chemical analysis, BET and X-ray diffraction (XRD). (author)

  7. Low frequency dielectric relaxation processes and ionic conductivity of montmorillonite clay nanoparticles colloidal suspension in poly(vinyl pyrrolidone−ethylene glycol blends

    Directory of Open Access Journals (Sweden)

    2008-11-01

    Full Text Available The dielectric dispersion behaviour of montmorillonite (MMT clay nanoparticles colloidal suspension in poly(vinyl pyrrolidone-ethylene glycol (PVP-EG blends were investigated over the frequency range 20 Hz to 1 MHz at 30°C. The 0, 1, 2, 3, 5 and 10 wt% MMT clay concentration of the weight of total solute (MMT+PVP were prepared in PVP-EG blends using EG as solvent. The complex relative dielectric function, alternating current (ac electrical conductivity, electric modulus and impedance spectra of these materials show the relaxation processes corresponding to the micro-Brownian motion of PVP chain, ion conduction and electrode polarization phenomena. The real part of ac conductivity spectra of these materials obeys Jonscher power law σ′(ω =σdc + Aωn in upper frequency end of the measurement, whereas dispersion in lower frequency end confirms the presence of electrode polarization effect. It was observed that the increase of clay concentration in the PVP-EG blends significantly increases the ac conductivity values, and simultaneously reduces the ionic conductivity relaxation time and electric double layer relaxation time, which suggests that PVP segmental dynamics and ionic motion are strongly coupled. The intercalation of EG structures in clay galleries and exfoliation of clay sheets by adsorption of PVP-EG structures on clay surfaces are discussed by considering the hydrogen bonding interactions between the hydroxyl group (–OH of EG molecules, carbonyl group (C=O of PVP monomer units, and the hydroxylated aluminate surfaces of the MMT clay particles. Results suggest that the colloidal suspension of MMT clay nano particles in the PVP-EG blends provide a convenient way to obtain an electrolyte solution with tailored electrical conduction properties.

  8. Preparación y propiedades de una arcilla montmorillonita pilareada con polihidroxicationes de aluminio Preparation and properties of a montmorillonite clay pillared with aluminium polyhydroxications

    Directory of Open Access Journals (Sweden)

    Sibele B. C. Pergher

    1999-09-01

    Full Text Available Montmorillonite clay from Brazil was pillared with aluminium polyhydroxications. The influence of Al/Mont ratio and calcination temperature in the properties of the prepared materials was studied. Results showed that the pillarization process increases the basal spaces of the natural clay from 9,7 to 18,5Å and the superficial area from 41 to ~230m2/g. The calcination process at different temperatures showed that the pillared material was stable until 600oC but the adequate temperature for calcination was 450oC. Materials prepared with different Al/Mont ratios showed the maximum Al incorporation for ratios >10meq Al/g and a good distribution for rations >15meq Al/g.

  9. Rheology of polyaniline-dinonylnaphthalene disulfonic acid (DNNDSA) montmorillonite clay nanocomposites in the sol state: shear thinning versus pseudo-solid behavior.

    Science.gov (United States)

    Garai, Ashesh; Nandi, Arun K

    2008-04-01

    The melt rheology of polyaniline (PANI)-dinonylnaphthalenedisulfonic acid (DNNDSA) gel nanocomposites (GNCs) with organically modified (modified with cetyl trimethylammonium bromide)-montmorillonite (om-MMT) clay has been studied for three different clay concentrations at the temperature range 120-160 degrees C. Field emission scanning electron microscopy (FE-SEM), wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC) and dc-conductivity data (approximately 10(-3) S/cm) indicate that the PANI-DNNDSA melt is in sol state and it is not de-doped at that condition. The WAXS data indicate that in GNC-1 sol clay tactoids are in exfoliated state but in the other sols they are in intercalated state. The zero shear viscosity (eta0), storage modulus (G') and loss modulus (G") increase than that of pure gel in the GNCs. The pure sol and the sols of gel nanocomposites (GNCs) exhibit Newtonian behavior for low shear rate (clay concentration and the power law index (n) decreases with increase in clay concentration in the GNCs indicating increased shear thinning for the clay addition. Thus the sols of om-clay nanocomposites of PANI-DNNDSA system are easily processible. The storage modulus (G') of GNC sols are higher than that of pure PANI-DNNDSA sol, GNC1 sol shows a maximum of 733% increase in storage modulus and the percent increase decreases with increase in temperature. Exfoliated nature of clay tactoids has been attributed for the above dramatic increase of G'. The PANI-DNNDSA sol nanocomposites behave as a pseudo-solid at higher frequency where G' and loss modulus (G") show a crossover point in the frequency sweep experiment at a fixed temperature. The crossover frequency decreases with increase in clay concentration and it increases with increase in temperature for GNC sols. The pseudo-solid behavior has been explained from jamming or network formation of clay tactoids under shear. A probable explanation of the two apparently contradictory phenomena

  10. Synthesis and Characterization of Polystyrene-Montmorillonite Nanocomposite Particles Using an Anionic-Surfactant-Modified Clay and Their Friction Performance

    Directory of Open Access Journals (Sweden)

    Chengcheng Yu

    2018-06-01

    Full Text Available Polystyrene-organo-montmorillonite (PS-OMMT nanocomposite particles were prepared via emulsion polymerization of styrene in the presence of montmorillonite modified with an anionic surfactant, sodium lauryl sulfonate (SLS, and its tribological properties as an additive to polyalphaolefin (PAO were tested. The results of Fourier transform infrared spectroscopy (FT-IR, X-ray diffraction (XRD and thermogravimetric analysis (TGA showed that SLS molecules resided in the montmorillonite (MMT interlayer space. The effects of OMMT on the morphology and properties of the nanocomposites were also investigated. Gel permeation chromatography (GPC and dynamic light scattering (DLS demonstrate that the presence of OMMT can effectively reduce the average molecular weight and average particle size of PS. XRD and transmission electron microscopy (TEM of the PS-OMMT nanocomposites indicate that exfoliated and intercalated structures form and that the MMT layers either are partly embedded inside the PS particles or remain on their surface. Compared with pure PS, the PS-OMMT nanocomposites possessed higher stability to thermal decomposition and higher glass transition temperatures. Adding nanocomposite particles reduces the friction coefficient, and thus, the antiwear properties of the PAO are significantly improved. The PS-OMMT-3 (3 wt % of OMMT based on styrene particles have the best tribological performance and maintained a stable, very low coefficient of friction of 0.09.

  11. Cu2+ Montmorillonite K10 Clay Catalyst as a Green Catalyst for Production of Stearic Acid Methyl Ester: Optimization Using Response Surface Methodology (RSM

    Directory of Open Access Journals (Sweden)

    Enas A. Almadani

    2018-01-01

    Full Text Available Clay catalyst has received much attention to replace the homogeneous catalysts in the esterification reaction to produce fatty acid methyl ester as the source of biodiesel as it is low cost, easily available, as well as environmental friendly. However, the use of unmodified clay, in particular montmorillonite K10 (MMT K10, for the esterification of fatty acids showed that the acid conversion was less than 60% and this is not preferable to the production of biodiesel. In this study, synthesis of stearic acid methyl ester using Cu2+-MMT K10 (Cu-MMT K10 was successfully optimized via response surface methodo-logy (RSM based on 3-variable of Box-Behnken design (BB. The parameters were; reaction time (5-180 minutes, reaction temperature (80-120 oC and concentration of Cu2+ in MMT K10 (0.25-1 M. The use of RSM in optimizing the conversion of stearic acid was successfully developed as the actual experimental conversion of stearic acid was found similar to the actual values under the optimum conditions. The model equation predicted that the following conditions would generate the maximum conversion of stearic acid (87.05 %reaction time of 62 minutes, a reaction temperature of 80 oC and catalyst used is 1.0 M Cu-MMT K10. This finding can be considered as green catalytic process as it worked at moderate reaction temperature using low cost clay catalyst with a short reaction time. Copyright © 2018 BCREC Group. All rights reserved Received: 26th July 2017; Revised: 13rd January 2018; Accepted: 13rd January 2018; Available online: 22nd January 2018; Published regularly: 2nd April 2018 How to Cite: Almadani, E.A., Harun, F.W., Radzi, S.M., Muhamad, S.K. (2018. Cu2+ Montmorillonite K10 Clay Catalyst as a Green Catalyst for Production of Stearic Acid Methyl Ester: Optimization Using Response Surface Methodology (RSM. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (1: 187-195 (doi:10.9767/bcrec.13.1.1397.187-195

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

    Science.gov (United States)

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

    2016-03-05

    Montmorillonite, also known as Cloisite(®)Na(+) (CNa(+)), is a natural clay with a wide range of well-documented and novel applications, such as pharmaceutical products or food packaging. Although considered a low toxic product, the expected increased exposure to CNa(+) arises concern on the potential consequences on human and environmental health especially as its genotoxicity has scarcely been investigated so far. Thus, we investigated, for the first time, the influence of non-cytotoxic concentrations of CNa(+) (15.65, 31.25 and 62.5 μg/mL) on genomic instability of human hepatoma cell line (HepG2) by determining the formation of micronuclei (MNi), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) with the Cytokinesis block micronucleus cytome assay. Further on we studied the influence of CNa(+) on the expression of several genes involved in toxicity mechanisms using the real-time quantitative PCR. The results showed that CNa(+) increased the number of MNi, while the numbers of NBUDs and NPBs were not affected. In addition it deregulated genes in all the groups studied, mainly after longer time of exposure. These findings provide the evidence that CNa(+) is potentially genotoxic. Therefore further studies that will elucidate the molecular mechanisms involved in toxic activity of CNa(+) are needed for hazard identification and human safety assessment. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Hydrothermal effects on montmorillonite

    International Nuclear Information System (INIS)

    Pusch, R.; Karnland, O.

    1988-06-01

    Hydrothermal effects on montmorillonite clay are usually taken to have the form of conversion of this clay mineral to other species, such as illite, disregarding microstructural alteration and cementation caused by precipitation of silica and other compounds. The report is focussed on identification of the primary processes that are involved in such alteration, the release of silica and the microstructural changes associated with heating being of major interest. In the first test phase, Na montmorillonite in distilled water was investigated by XRD, rheology tests and electron microscopy after heating to 60-225 0 C for 0.01 to 1 year. The preliminary conclusions are that heating produces contraction of the particle network to form dense 'branches', the effect being most obvious at the highest temperature but of significance even at 60-100 0 C. Release of substantial amounts of silica gas been documented for temperatures exceeding 150 0 and precipitation of silica was observed on cooling after the hydrothermal testing under the closed conditions that prevailed throughout the tests. The precipitates, which appeared to be amorphous and probably consisted of hydrous silica gels, were concluded to have increased the mechanical strength and caused some brittleness, particularly of the dense clays. The nature of the silica release, which is assumed to be associated with beidellitization, may be closely related to an unstable state of a certain fraction of tetrahedral silica at heat-inducted transfer between two different crystal modes of montmorillonite. (orig.)

  14. New Method for Nucleophilic Substitution on Hexachlorocyclotriphosphazene by Allylamine Using an Algerian Proton Exchanged Montmorillonite Clay (Maghnite-H+ as a Green Solid Catalyst

    Directory of Open Access Journals (Sweden)

    Lahouaria Medjdoub

    2016-08-01

    Full Text Available Nucleophilic substitution on hexachlorocyclotriphosphazene (HCCTP with allylamine in order to give hexa(allylaminocyclotriphosphazene (HACTP  is performed for the first time under mild conditions by using diethylether as solvent to replace benzene which is very toxic. The reaction time is reduced to half and also performed at room temperature but especially in the presence of an eco-catalyst called Maghnite-H+. This catalyst has a significant role in the industrial scale. In fact, the use of Maghnite is preferred for its many advantages: a very low purchase price compared to other catalysts, the easy removal of the reaction mixture. Then, Maghnite-H+ is became an excellent catalyst for many chemical reactions. The structure of HACTP synthesized in the presence of Maghnite-H+ to 5% by weight is confirmed by 1H-NMR, 13C-NMR, 31P-NMR (Nuclear magnetic resonance and FTIR (Fourier Transform Infrared spectroscopy. MALDI-TOF (Matrix-Assisted Laser Desorption/Ionisation-time-of-flight mass spectrometry is used to establish the molecular weight of HACTP which is 471 g/mol. DSC (Differential Scanning Calorimetery and TGA (Thermogravimetric Analysis show that HACTP is a crystalline product with a melting point of 88 °C. It is reactive after melting but is degraded from 230 °C. Copyright © 2016 BCREC GROUP. All rights reserved Received: 28th September 2015; Revised: 5th December 2015; Accepted: 4th January 2016 How to Cite: Medjdoub, L., Mohammed, B. (2016. New Method for Nucleophilic Substitution on Hexachlorocyclotriphosphazene by Allylamine Using an Algerian Proton Exchanged Montmorillonite Clay (Maghnite-H+ as a Green Solid Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 151-160 (doi:10.9767/bcrec.11.2.541.151-160 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.541.151-160

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

    Energy Technology Data Exchange (ETDEWEB)

    Maisanaba, Sara, E-mail: saramh@us.es [Area of Toxicology, Faculty of Pharmacy, University of Sevilla, Profesor García González no. 2, 41012 Seville (Spain); Hercog, Klara; Filipic, Metka [National Institute of Biology, Department for Genetic Toxicology and Cancer Biology, Vecna pot 111, 1000 Ljubljana (Slovenia); Jos, Ángeles [Area of Toxicology, Faculty of Pharmacy, University of Sevilla, Profesor García González no. 2, 41012 Seville (Spain); Zegura, Bojana [National Institute of Biology, Department for Genetic Toxicology and Cancer Biology, Vecna pot 111, 1000 Ljubljana (Slovenia)

    2016-03-05

    Highlights: • Cloisite{sup ®}Na{sup +} has a wide range of well-documented and novel applications. • Cloisite{sup ®}Na{sup +} induces micronucleus, but not nuclear bridges or nuclear buds in HepG2 cells. • Cloisite{sup ®}Na{sup +} induces changes in the gene expression. • Gene alteration is presented mainly after 24 h of exposure to Cloisite{sup ®}Na{sup +}. - Abstract: Montmorillonite, also known as Cloisite{sup ®}Na{sup +} (CNa{sup +}), is a natural clay with a wide range of well-documented and novel applications, such as pharmaceutical products or food packaging. Although considered a low toxic product, the expected increased exposure to CNa{sup +} arises concern on the potential consequences on human and environmental health especially as its genotoxicity has scarcely been investigated so far. Thus, we investigated, for the first time, the influence of non-cytotoxic concentrations of CNa{sup +} (15.65, 31.25 and 62.5 μg/mL) on genomic instability of human hepatoma cell line (HepG2) by determining the formation of micronuclei (MNi), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) with the Cytokinesis block micronucleus cytome assay. Further on we studied the influence of CNa{sup +} on the expression of several genes involved in toxicity mechanisms using the real-time quantitative PCR. The results showed that CNa{sup +} increased the number of MNi, while the numbers of NBUDs and NPBs were not affected. In addition it deregulated genes in all the groups studied, mainly after longer time of exposure. These findings provide the evidence that CNa{sup +} is potentially genotoxic. Therefore further studies that will elucidate the molecular mechanisms involved in toxic activity of CNa{sup +} are needed for hazard identification and human safety assessment.

  16. Comparative evaluation between montmorillonite clay/LLDPE and potassium hexaniobate/LLDPE nanocomposites: characterization of mechanical and transport properties; Avaliacao comparativa entre os nanocompositos de argila motmorilonita/LLDPE e com hexaniobato de potassio/LLDPE: caracterizacao das propriedades mecanicas e de transporte

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, Daniel; Otaguro, Harumi [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Quimica; Ruvolo Filho, Adhemar C. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

    2014-06-01

    Linear low density polyethylene-montmorillonite clay and linear low density polyethylene-organophilic niobate nanocomposites were obtained from dilution of masterbatch with 20% w/w of fillers in the LLDPE matrix by melt intercalation using a twin-screw extruder, obtaining nanocomposites with 1.5% up to 10.0% w/w of filler. In this study mechanical and water vapor and oxygen permeation tests were used to characterize the nanocomposites. In mechanical tests an increase of modulus values and decrease of toughness value by increasing concentration of montmorillonite clay were observed. The behavior of LLDPE-organophilic niobate nanocomposites was similar to LLDPE-montmorillonite clay nanocomposites but softer due to hexaniobate structure. The distribution of the organoclay is more homogeneous than organophilic niobate to concentrations below 10.0% filler using the SEM/FEG. It is possible to see a decrease in the permeability value with increasing concentration of montmorillonite clay for both gases used. In the LLDPE-organophilic niobate nanocomposites a decrease of permeability value occurs followed by an increase of permeability value for both gases used, with increasing concentration of organophilic niobate. Furthermore, it was observed that the polarity of the gas used is an important factor in the diffusion process through the nanocomposite. (author)

  17. Spherical LDH-Ag°-montmorillonite heterocoagulated system with a pH-dependent sol-gel structure for controlled accessibility of AgNPs immobilized on the clay lamellae.

    Science.gov (United States)

    Deák, Ágota; Janovák, László; Tallósy, Szabolcs Péter; Bitó, Tamás; Sebők, Dániel; Buzás, Norbert; Pálinkó, István; Dékány, Imre

    2015-02-17

    Aqueous suspensions of spherical ZnMgAl-layered double hydroxides [LDH(sph)] and antibacterial silver nanoparticles (AgNPs) deposited on the lamellae of montmorillonite were used for the synthesis of composites, which behave like coherent gels at low pH (≲4.5) and incoherent sols at higher pH (≳4.5). The composition of the composite was chosen as LDH(sph)/Ag°-montm. = 25:75 wt % in order to ensure a sol-gel transition that can also be characterized by viscometry. This pH-sensitive heterocoagulated system consisting of oppositely charged colloid particles was suitable for the release of antimicrobial AgNPs immobilized on the clay lamellae via a pH-controlled gel-sol transition. The heterocoagulation process was also characterized by surface charge titration measurements. Spherical LDH/Ag°-montmorillonite composite samples were identified by X-ray diffraction (XRD) measurements. The morphological properties of the composites were studied, and the presence of the heterocoagulated structure was confirmed by scanning electron microscopy (SEM). The nanoscale structure of the LDH(sph)-Ag°-montmorillonite composite obtained was also verified by small-angle X-ray scattering (SAXS), and the rheological characteristics were studied at various pH values. The viscosity and yield value of the composite decreased by an order of magnitude upon increasing the pH from 3.0 to 5.5. The sol-gel transition of the composite suspension was reversible in the previously mentioned pH range.

  18. Microwave-Assisted Synthesis of a Natural Insecticide on Basic Montmorillonite K10 Clay. Green Chemistry in the Undergraduate Organic Laboratory

    Science.gov (United States)

    Dintzner, Matthew R.; Wucka, Paul R.; Lyons, Thomas W.

    2006-01-01

    A detailed investigation of the clay-catalyzed condensation of sesamol and other phenols with 3-methyl-2-butenal to give methylenedioxyprecocene (MDP) and other chromenes is presented. The clay-catalyzed microwave-assisted condensation of sesamol with 3-methyl-2-butenal is appropriate for incorporation into undergraduate organic laboratory…

  19. Pentachlorophenol radical cations generated on Fe(III)-montmorillonite initiate octachlorodibenzo-p-dioxin formation in clays: DFT and FTIR studies

    Science.gov (United States)

    Gu, Cheng; Liu, Cun; Johnston, Cliff T.; Teppen, Brian J.; Li, Hui; Boyd, Stephen A.

    2011-01-01

    Octachlorodibenzodioxin (OCDD) forms spontaneously from pentachlorophenol (PCP) on the surfaces of Fe(III)-saturated smectite clay (1). Here, we used in situ FTIR methods and quantum mechanical calculations to determine the mechanism by which this reaction is initiated. As the clay was dehydrated, vibrational spectra showed new peaks that grew and then reversibly disappeared as the clay rehydrated. First principle DFT calculations of hydrated Fe-PCP clusters reproduced these transient FTIR peaks when inner-sphere complexation and concomitant electron transfer produced Fe(II) and PCP radical cations. Thus, our experimental (FTIR) and theoretical (quantum mechanical) results mutually support the hypothesis that OCDD formation on Fe-smectite surfaces is initiated by the reversible formation of metastable PCP radical cations via single electron transfer from PCP to Fe(III). The negatively charged clay surface apparently selects for this reaction mechanism by stabilizing PCP radical cations. PMID:21254769

  20. A comparative UV-vis-diffuse reflectance study on the location and interaction of cerium ions in Al- and Zr-pillared montmorillonite clays

    International Nuclear Information System (INIS)

    Rao, G. Ranga; Mishra, Braja Gopal

    2005-01-01

    The environment, location and interaction of the Ce 3+ ions in the micropores of Al- and Zr-pillared clays have been studied by UV-vis-diffuse reflectance spectroscopy (UV-vis-DRS). The DRS spectra show that the chemical environment of the Ce 3+ ions in cerium exchanged clay is different from that of the Al- and Zr-pillared clays. The Al-Ce pillared clays (Al-Ce-PM) show four distinct absorption bands at 224, 263, 294 and 342 nm in the UV region which are attributed to 4f → 5d interconfigurational transitions of Ce 3+ ions associated with alumina pillars. The O 2- → Ce 3+ charge transfer band observed at 263 nm for Ce-exchanged and Al-Ce-PM clays is blue shifted by 10 nm for Ce-Zr-pillared clays (Ce-Zr-PM) due to fully hydrated Ce 3+ ions. The Ce 3+ ions are incorporated in the Al- and Zr-pillars possibly as AlCeO 3 and Ce x Zr 1-x O 2 particles upon heat treatment

  1. 60Co retention by Mexican montmorillonites

    International Nuclear Information System (INIS)

    Pacheco, G.; Martinez, V.; Bosch, P.; Bulbulian, S.

    1995-01-01

    Radioactive elements may be retained by clays. The ability of natural Mexican clays to retain radioactive Co from aqueous solutions, is discussed. Experiments were performed with solutions containing labeled cobalt. The effect of contact time on Co 2+ retention was studied. It was found that the Co 2+ uptake value in dehydrated montmorillonites is between 0.30 and 0.70 meq g -1 of clay. A sorption sequence was obtained for the various clays. The samples were characterized, before and after cobalt exchange, by X-ray diffraction. (author). 7 refs., 3 figs., 3 tabs

  2. Adsorption of Carbon Dioxide, Methane, and Their Mixtute by Montmorillonite in the Presence of Water

    KAUST Repository

    Kadoura, Ahmad Salim; Nair, Arun Kumar Narayanan; Sun, Shuyu

    2016-01-01

    Using grand canonical Monte Carlo (GCMC) simulations, we study the adsorption behavior of CH4, CO2, and their mixture at 298.15 K and pressures up to 50 bar in Na-, Cs-, and Ca-montmorillonite clays in the presence of water. Montmorillonite clays

  3. Synthesis of magnetite from iron-rich mine water using sodium carbonate

    CSIR Research Space (South Africa)

    Akinwekomi, V

    2017-06-01

    Full Text Available is highly mineralised and technologies are required for the processing of the final sludge for possible industrial application. Conventionally, magnetite is synthesized using iron-rich, industrial grade chemical reagents making magnetite expensive to produce...

  4. Iron-rich Oxides at the Core-mantle Boundary

    Science.gov (United States)

    Wicks, J. K.; Jackson, J. M.; Sturhahn, W.; Bower, D. J.; Zhuravlev, K. K.; Prakapenka, V.

    2013-12-01

    ULVZ and show that a small amount of iron-rich (Mg,Fe)O can greatly reduce the average sound velocity of an aggregate assemblage. When combined with a geodynamic model of a solid ULVZ (Bower et al., 2011), we can directly correlate inferred sound velocities to mineralogy and predicted ULVZ shapes. In this presentation, our combined geodynamic and mineral physics model of a solid ULVZ will be used to explore the relationship between the observed sound velocities and mineralogy of ULVZs with added insight into ULVZ morphology.

  5. Dynamics of water and ions in clays of type montmorillonite by microscopic simulation and quasi-elastic neutron scattering; Dynamique de l'eau et des ions dans des argiles de type montmorillonite par simulation microscopique et diffusion quasi-elastique des neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Malikova, N

    2005-09-15

    Montmorillonite clays in low hydration states, with Na{sup +} and Cs{sup +} compensating counter ions, are investigated by a combination of microscopic simulation and quasi-elastic neutron scattering to obtain information on the local structure and dynamics of water and ions in the interlayer. At first predictions of simulation into the dynamics of water and ions at elevate temperatures are shown (0 deg C 80 deg C, pertinent for the radioactive waste disposal scenario) Marked difference is observed between the modes of diffusion of the Na{sup +} and C{sup +} counter ions. In water dynamics, a significant step towards bulk water behaviour is seen on transition from the mono- to bilayer states. Secondly, a detailed comparison between simulation and quasi-elastic neutron scattering (Neutron Spin Echo and Time-of-Flight) regarding ambient temperature water dynamics is presented. Overall, the approaches are found to be in good agreement with each other and limitations of each of the methods are clearly shown. (author)

  6. Montmorillonite Nanoparticles

    Directory of Open Access Journals (Sweden)

    H. Almasi

    2009-12-01

    Full Text Available Novel citric acid modified starch-carboxy methyl cellulose (CMC -montmorillonite (MMT bionanocomposite films were prepared by casting method and the effect of MMT on the structural and physical properties of the starch-CMC biocomposites was studied. X-ray diffraction test showed thatstrong polar interactions between the hydroxyl groups present in the starch and CMC chains and in the silicate layers led to intercalation of biopolymer chains into MMT layers galleries. The water vapor permeability decreased from 2.44 to 1.13×10-7 g/mhPa as the MMT percentage increased from0 to 7%. At the level of 7% MMT, the composite films showed the highest ultimate tensile strength (27.55 MPa and lowest strain-to-break (18.25%. The DSC tests showed that, the temperature position of the melting peak increased from 221.5°C to 243.0°C as MMT content increased from 1 to 7%, but the glass transition decreased and gradually disappeared.

  7. Preparation and characterization of exfoliated polyaniline/montmorillonite nanocomposites

    International Nuclear Information System (INIS)

    Narayanan, Binitha N.; Koodathil, Ranjana; Gangadharan, Tripti; Yaakob, Zahira; Saidu, Femina K.; Chandralayam, Soumini

    2010-01-01

    Transition metal ions were exchanged with the interlamellar cations of montmorillonite clays and polymerization of aniline was done within the layers. The delaminated clay layers upon ion exchange resulted in exfoliated polyaniline/clay nanocomposite formation which has profound effects on polymer structure, properties and electrical conduction mechanisms. Here we offer polyaniline (PANI)/montmorillonite exfoliated nanocomposite synthesized through a simple, cheap route which need not require complicated and less economical organophilic modification. The prepared composites were characterized using XRD, FTIR, and TG/DTA to prove exfoliation.

  8. Preparation and characterization of exfoliated polyaniline/montmorillonite nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Narayanan, Binitha N., E-mail: binithann@yahoo.co.i [Department of Chemistry, Sree Neelakanta Government Sanskrit College, Pattambi, Palakkad 679306, Kerala (India); Department of Chemical and Process Engineering, Faculty of Engineering, National University of Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Koodathil, Ranjana; Gangadharan, Tripti [Department of Chemistry, Sree Neelakanta Government Sanskrit College, Pattambi, Palakkad 679306, Kerala (India); Yaakob, Zahira [Department of Chemical and Process Engineering, Faculty of Engineering, National University of Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Saidu, Femina K.; Chandralayam, Soumini [Department of Chemistry, Sree Neelakanta Government Sanskrit College, Pattambi, Palakkad 679306, Kerala (India)

    2010-04-15

    Transition metal ions were exchanged with the interlamellar cations of montmorillonite clays and polymerization of aniline was done within the layers. The delaminated clay layers upon ion exchange resulted in exfoliated polyaniline/clay nanocomposite formation which has profound effects on polymer structure, properties and electrical conduction mechanisms. Here we offer polyaniline (PANI)/montmorillonite exfoliated nanocomposite synthesized through a simple, cheap route which need not require complicated and less economical organophilic modification. The prepared composites were characterized using XRD, FTIR, and TG/DTA to prove exfoliation.

  9. [Adsorptive Stabilization of Soil Cr (VI) Using HDTMA Modified Montmorillonite].

    Science.gov (United States)

    2016-03-15

    A series of organo-montomorillonites were prepared using Na-montomorillonite and hexadecyl trimethyl ammonium bromide (HDTMA). The organo-montomorillonites were then investigated for the remediation of Cr(VI) contaminated soils. FT-IR, XRD, SEM and N2 -BET, CEC, Zeta potential measurement were conducted to understand the structural changes of montmorillonites as different amounts of HDTMAs were added as modifier. The characterization results indicated that the clay interlayer spacing distance increased from 1. 25 nm to 2. 13 nm, the clay surface roughness decreased, the clay surface area reduced from 38.91 m² · g⁻¹ to 0.42 m² · g⁻¹, the clay exchangeable cation amount reduced from 62 cmol · kg⁻¹ to 9.9 cmol · kg⁻¹ and the clay surface charge changed from -29.1 mV to 5.59 mV as the dosage of HDTMA in montmorillonite was increased. The TCLP (toxicity characteristic leaching procedure) was used to evaluate the leachate toxicity of Cr(VI). The effects of the initial soil Cr(VI) concentration, montmorillonites dosage, reaction time and HDTMA modification amount were investigated, respectively. The results revealed that modification of montmorillonites would manifest an attenuated physical adsorptive effect and an enhanced electrostatic adsorptive effect on Cr(VI), suggesting electrostatic effect was the major force that resulted in improved Cr(VI) adsorption onto HDTMA modified montmorillonites.

  10. Nontronite and Montmorillonite as Nutrient Sources for Life on Mars

    Science.gov (United States)

    Craig, P. I.; Mickol, R. L.; Archer, P. D.; Kral, T. A.

    2017-01-01

    Clay minerals have been identified on Mars' oldest (Noachian) terrain and their presence suggests long-term water-rock interactions. The most commonly identified clay minerals on Mars to date are nontronite (Fe-smectite) and montmorillonite (Al-smectite) [1], both of which contain variable amounts of water both adsorbed on their surface and within their structural layers. Over Mars' history, these clay miner-al-water assemblages may have served as nutrient sources for microbial life.

  11. Break-up of Ca-montmorillonite particles by Na-montmorillonite

    International Nuclear Information System (INIS)

    Hedstroem, Magnus; Birgersson, Martin

    2012-01-01

    Document available in extended abstract form only. In the Swedish KBS-3 concept for a geological deep storage of spent nuclear fuel, bentonite of high montmorillonite content is proposed to serve as a buffer surrounding copper canisters containing the spent fuel. Montmorillonite has an exceptional affinity for water which results in the build-up of a swelling pressure when bentonite is placed in a confined volume. However, there is a concern that during and after a glaciation, meltwater of low ionic strength may cause the bentonite to swell extensively into fractures and turn into a sol that could be transported away by the seeping water. It is thus warranted to understand the behaviour of montmorillonite at aqueous condition of low ionic strength. Turbidity measurements were used to a large extent in previous work to follow the free swelling or settling process of montmorillonite in various aqueous solutions and thereby give information regarding sol formation. From theory we know that turbidity of a suspension is proportional to the particle concentration. However turbidity is also proportional to V p 2 where V p is the volume of the scattering particle. Thus the fact that turbidity of a Ca-montmorillonite suspension is higher than the turbidity of a Na- montmorillonite suspension of the same clay concentration indicates that Na-montmorillonite separate into smaller particles than Ca-montmorillonite. In this work we make use this size dependence to quantify the difference between Wyoming, Milos and Kutch montmorillonite in particular with respect to how mixed Ca/Na montmorillonite systems behave. Some Ca/Mg, Mg/Na and Na/K systems are also included for comparison. Figure 1 shows the final (stabilized) turbidity response of mixed Wy-Ca/Na montmorillonite as a function of the fraction of Ca 2+ in the clay. Starting material are suspensions of homo-ionic Wy-Ca and Wy-Na montmorillonite at a concentration of 1 g/l. The turbidity of the suspensions of the homo

  12. Factors influencing As(V) stabilization in the mine soils amended with iron-rich materials.

    Science.gov (United States)

    Kim, Mijin; Kim, Juhee; Kim, Minhee; Kim, Yong-Seong; Nam, Seung Mo; Moon, Deok Hyun; Hyun, Seunghun

    2017-09-04

    Chemical stability of As(V) in amended mine-impacted soils was assessed according to functions of incubation period (0, 1, 2, 4, and 6 months), amendment dose (2.5 and 5%), and application timing (0 and 3rd month). Six soils contaminated with 26-209 mg kg -1 of As(V) were collected from two abandoned mine sites and were treated with two alkaline iron-rich materials (mine discharge sludge (MS) and steel-making slag (SS)). Seventeen to 23% of As(V) in soils was labile. After each designated time, As(V) stability was assessed by the labile fractions determined with sequential extraction procedures (F1-F5). Over 6 months, a reduction (26.9-70.4%) of the two labile fractions (F1 and F2) and a quantitative increase (7.4-29.9%) of As(V) in F3 were observed (r 2  = 0.956). Two recalcitrant fractions (F4 and F5) remained unchanged. Temporal change of As(V) stability in a sample was well described by the two-domain model (k fast , k slow , and F fast ). The stabilization (%) correlated well with the fast-stabilizing domain (F fast ), clay content (%), and Fe oxide content (mg kg -1 ), but correlated poorly with kinetic rate constants (k fast and k slow ). Until the 3rd month, the 2.5%-MS amended sample resulted in lower As(V) stabilization (25-40%) compared to the 5% sample (50-60%). However, the second 2.5% MS addition on the 2.5% sample upon the lapse of the 3rd month led to a substantial reduction (up to 38%) of labile As(V) fraction in the following 4th and 6th months. As a result, an additional 15-25% of As(V) stability was obtained when splitting the amendment dose into 3-month intervals. In conclusion, the As(V) stabilization by Fe-rich amendment is time-dependent and its efficacy can be improved by optimizing the amendment dose and its timing.

  13. Influence of montmorillonite on antimicrobial activity of tetracycline and ciprofloxacin

    Science.gov (United States)

    Lv, Guocheng; Pearce, Cody W.; Gleason, Andrea; Liao, Libing; MacWilliams, Maria P.; Li, Zhaohui

    2013-11-01

    Antibiotics are used not only to fight infections and inhibit bacterial growth, but also as growth promotants in farm livestock. Farm runoff and other farm-linked waste have led to increased antibiotic levels present in the environment, the impact of which is not completely understood. Soil, more specifically clays, that the antibiotic contacts may alter its effectiveness against bacteria. In this study a swelling clay mineral montmorillonite was preloaded with antibiotics tetracycline and ciprofloxacin at varying concentrations and bioassays were conducted to examine whether the antibiotics still inhibited bacterial growth in the presence of montmorillonite. Escherichia coli was incubated with montmorillonite or antibiotic-adsorbed montmorillonite, and then the number of viable bacteria per mL was determined. The antimicrobial activity of tetracycline was affected in the presence of montmorillonite, as the growth of non-resistant bacteria was still found even when extremely high TC doses were used. Conversely, in the presence of montmorillonite, ciprofloxacin did inhibit E. coli bacterial growth at high concentrations. These results suggest that the effectiveness of antimicrobial agents in clayey soils depends on the amount of antibiotic substance present, and on the interactions between the antibiotic and the clays in the soil, as well.

  14. Colour, compressive strength and workability of mortars with an iron rich sewage sludge ash

    DEFF Research Database (Denmark)

    Kappel, Annemette; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie

    2017-01-01

    This paper reports a study of the colour, compressive strength and workability of mortar when cement is partly replaced by sewage sludge ash (SSA). In the study, an iron rich SSA was dry milled into six different fractions. The results showed that the colour, compressive strength and workability...

  15. Nanocomposites of polypropylene and organophilic montmorillonite clay: X-ray diffraction, infrared spectroscopy with Fourier transform and water permeation;Nanocomposito de prolipropileno e argila montmorilonita organifilica: difracao de raios-X, espectroscopia na regiao do infravermelho e permeacao ao vapor de agua

    Energy Technology Data Exchange (ETDEWEB)

    Morelli, Fernanda C; Ruvolo Filho, Adhemar, E-mail: fer_morelli@yahoo.com.b, E-mail: adhemar@power.ufscar.b [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2009-07-01

    In this work were prepared nanocomposites of polypropylene and organophilic montmorillonite Cloisite 20A with concentrations of 1.5%, 2.5%, 5.0% and 7.5% clay and graft polypropylene with maleic anhydride as compatibilizer. The mixture was made in the melt state using a twin screw extruder. The materials were characterized by x-ray diffraction, infrared spectroscopy with Fourier transform and analysis of water vapor permeation. The results of x-ray diffraction and infrared spectroscopy indicates the formation of nanocomposites with structures probably exfoliate and / or intercalated for concentrations of 1.5% and 2.5% clay, and provided a marked decrease in the water permeability, corroborating with other analysis. (author)

  16. Hydrogen isotope ratios of clay minerals constituting clay veins found in granitic rocks in Hiroshima Prefecture

    International Nuclear Information System (INIS)

    Kitagawa, Ryuji; Kakitani, Satoru; Kuroda, Yoshimatsu; Matsuo, Sadao; Suzuoki, Tetsuro.

    1980-01-01

    The deuterium content of the constitutional and interlayer water extracted from the clay minerals (illite, montmorillonite, interstratified illite-montmorillonite mineral, kaolinite, halloysite) constituting the clay veins found in the granitic rocks in Hiroshima Prefecture was measured. The clay minerals were heated at 270 deg C to extract the interlayer water, then heated to 1,400 or 1,500 deg C to extract the constitutional water. The deuterium content of the local surface water collected from sampling points was measured. In the clay veins formed along perpendicular joints, the constituent clay minerals change from lower to upper part: illite → montmorillonite → kaolinite → halloysite. The deuterium content values of the constitutional water for illite and montmorillonite were estimated to be -67 to -69% and -86 to -89%, respectively. The deuterium content values of the constitutional water for halloysite range from -68 to -80% and for kaolinite from -63 to -67%. (J.P.N.)

  17. Preparação e Caracterização de Nanofibras de Nanocompósitos de Poliamida 6,6 e Argila Montmorilonita Preparation and Characterization of Nanofibers of Polyamide 66 and Montmorillonite Clay Nanocomposites

    Directory of Open Access Journals (Sweden)

    Camila R. dos Santos

    2011-01-01

    the great objective of researchers and industry, since these fibers have many applications. They can be produced by an electrospinning process from a polymeric solution. In this work, nanocomposites´ fibers of polyamide 66 and montmorillonite clay were obtained by melt mixing, following by electrospinning of the solution. Nanocomposites with three different clay concentrations, 2, 3 and 4 wt.%, were obtained by melt mixing, and solutions of these nanocomposites in formic acid were prepared at different concentrations. The influence of the clay addition, nanocomposites´ solution concentration, variation of the applied electric field on the mixture and solutions properties and on the average diameter of the nanofibers was studied. Wide-angle X-ray (WAXD and transmission electron microscopy (TEM measurements showed that the process of electrospinning was efficient in the maintenance of the clay exfoliation in the fibers. Results of scanning electron microscopy (SEM and differential scanning calorimetry (DSC showed that the fibers had average diameters of the order of nanometers, were cylindrical and not porous, having low degree of crystallinity and residual solvent. The addition of clay increased slightly the viscosity of the polymeric solution, which increased the nanofibers average diameter. It was also observed that the increase in the fiber diameters was proportional to the increase of the polymer concentration in the solution. Regarding the applied electric field, it was observed a tendency to reduction in the average diameter of the fibers with the reduction of this parameter.

  18. Montmorillonite-induced Bacteriophage φ6 Disassembly

    Science.gov (United States)

    Trusiak, A.; Gottlieb, P.; Katz, A.; Alimova, A.; Steiner, J. C.; Block, K. A.

    2012-12-01

    It is estimated that there are 1031 virus particles on Earth making viruses an order of magnitude more prevalent in number than prokaryotes with the vast majority of viruses being bacteriophages. Clays are a major component of soils and aquatic sediments and can react with RNA, proteins and bacterial biofilms. The clays in soils serve as an important moderator between phage and their host bacteria, helping to preserve the evolutionary balance. Studies on the effects of clays on viral infectivity have given somewhat contradictory results; possibly a consequence of clay-virus interactions being dependent on the unique structure of particular viruses. In this work, the interaction between montmorillonite and the bacteriophage φ6 is investigated. φ6 is a member of the cystovirus family that infects Pseudomonas syringe, a common plant pathogen. As a member of the cystovirus family with an enveloped structure, φ6 serves as a model for reoviruses, a human pathogen. Experiments were conducted with φ6 suspended in dilute, purified homoionic commercial-grade montmorillonite over a range of virus:clay ratios. At a 1:100000 virus:clay ratio, the clay reduced viral infectivity by 99%. The minimum clay to virus ratio which results in a measurable reduction of P. syringae infection is 1:1. Electron microscopy demonstrates that mixed suspensions of smectite and virus co-aggregate to form flocs encompassing virions within the smectite. Both free viral particles as well as those imbedded in the flocs are seen in the micrographs to be missing the envelope- leaving only the nucleocapsid (NC) intact; indicating that smectite inactivates the virus by envelope disassembly. These results have strong implications in the evolution of both the φ6 virus and its P. syringae host cells. TEM of aggregate showing several disassembled NCs.

  19. Prebiotic RNA Synthesis by Montmorillonite Catalysis

    Directory of Open Access Journals (Sweden)

    Sohan Jheeta

    2014-08-01

    Full Text Available This review summarizes our recent findings on the role of mineral salts in prebiotic RNA synthesis, which is catalyzed by montmorillonite clay minerals. The clay minerals not only catalyze the synthesis of RNA but also facilitate homochiral selection. Preliminary data of these findings have been presented at the “Horizontal Gene Transfer and the Last Universal Common Ancestor (LUCA” conference at the Open University, Milton Keynes, UK, 5–6 September 2013. The objective of this meeting was to recognize the significance of RNA in LUCA. We believe that the prebiotic RNA synthesis from its monomers must have been a simple process. As a first step, it may have required activation of the 5'-end of the mononucleotide with a leaving group, e.g., imidazole in our model reaction (Figure 1. Wide ranges of activating groups are produced from HCN under plausible prebiotic Earth conditions. The final step is clay mineral catalysis in the presence of mineral salts to facilitate selective production of functional RNA. Both the clay minerals and mineral salts would have been abundant on early Earth. We have demonstrated that while montmorillonite (pH 7 produced only dimers from its monomers in water, addition of sodium chloride (1 M enhanced the chain length multifold, as detected by HPLC. The effect of monovalent cations on RNA synthesis was of the following order: Li+ > Na+ > K+. A similar effect was observed with the anions, enhancing catalysis in the following order: Cl− > Br− > I−. The montmorillonite-catalyzed RNA synthesis was not affected by hydrophobic or hydrophilic interactions. We thus show that prebiotic synthesis of RNA from its monomers was a simple process requiring only clay minerals and a small amount of salt.

  20. Adsorption of Carbon Dioxide, Methane, and Their Mixtute by Montmorillonite in the Presence of Water

    KAUST Repository

    Kadoura, Ahmad Salim

    2016-01-16

    Using grand canonical Monte Carlo (GCMC) simulations, we study the adsorption behavior of CH4, CO2, and their mixture at 298.15 K and pressures up to 50 bar in Na-, Cs-, and Ca-montmorillonite clays in the presence of water. Montmorillonite clays in the presence of preadsorbed water, preferentially adsorb CO2 over CH4 during both pure component and mixture adsorption. The atomistic model we have used, gives good agreement with available single-component experimental adsorption isotherms, for CH4 and CO2 molecules adsorbed onto montmorillonite clays in the presence of water. We observe the general trend that the presence of increasing preadsorbed water content in the clay interlayers, reduced adsorption amounts of pure CH4 and CO2 molecules. With a relatively large basal spacing (d= 30 Å), the favorability of adsorption of CO2 by montmorillonite at relatively low pressures and intermediate water contents has been demonstrated using simulations. GCMC simulation is also used to assess the effect of water on the adsorption of N2/CH4, H2 S/CH4, CO2/N2, and CO2/H2 S binary mixtures in Na-montmorillonite clay. The ideal adsorbed solution theory is shown to agree well with the observed adsorption capacities and selectivities of mixtures in Na-montmorillonite clay.

  1. The acid-base titration of montmorillonite

    Science.gov (United States)

    Bourg, I. C.; Sposito, G.; Bourg, A. C.

    2003-12-01

    Proton binding to clay minerals plays an important role in the chemical reactivity of soils (e.g., acidification, retention of nutrients or pollutants). If should also affect the performance of clay barriers for waste disposal. The surface acidity of clay minerals is commonly modelled empirically by assuming generic amphoteric surface sites (>SOH) on a flat surface, with fitted site densities and acidity constant. Current advances in experimental methods (notably spectroscopy) are rapidly improving our understanding of the structure and reactivity of the surface of clay minerals (arrangement of the particles, nature of the reactive surface sites, adsorption mechanisms). These developments are motivated by the difficulty of modelling the surface chemistry of mineral surfaces at the macro-scale (e.g., adsorption or titration) without a detailed (molecular-scale) picture of the mechanisms, and should be progressively incorporated into surface complexation models. In this view, we have combined recent estimates of montmorillonite surface properties (surface site density and structure, edge surface area, surface electrostatic potential) with surface site acidities obtained from the titration of alpha-Al2O3 and SiO2, and a novel method of accounting for the unknown initial net proton surface charge of the solid. The model predictions were compared to experimental titrations of SWy-1 montmorillonite and purified MX-80 bentonite in 0.1-0.5 mol/L NaClO4 and 0.005-0.5 mol/L NaNO3 background electrolytes, respectively. Most of the experimental data were appropriately described by the model after we adjusted a single parameter (silanol sites on the surface of montmorillonite were made to be slightly more acidic than those of silica). At low ionic strength and acidic pH the model underestimated the buffering capacity of the montmorillonite, perhaps due to clay swelling or to the interlayer adsorption of dissolved aluminum. The agreement between our model and the experimental

  2. EFFECT OF ORGANOPHILIZATION AND INTERLAMELLAR SILYLATION OF MONTMORILLONITE ON COMPATIBLIZATION OF POLYMER COMPOSITES

    Directory of Open Access Journals (Sweden)

    Mamdouh Abdel Rahim

    2016-12-01

    Full Text Available Sodium montmorillonite (Na-Mt was modified by cetyltriemethylammoniumbromide (CTAB through cation exchange technique followed by grafting with 3-aminopropyltriethoxysilane (APT. The effects of organophillic surface treatments of montmorillonite on compatibilization of natural rubber (NR /acrylonitrile butadiene rubber (NBR blends was investigated. Physico-mechanical properties of rubber nanocomposites compatibilized with organomodified montmorillonite revealed strong nanocomposite with high tensile properties, impact strength and good resistance to flex fatigue, abrasion and compression set. Dynamic mechanical thermal analysis (DMTA revealed a marked increase in storage modulus (E' and lesser damping characteristics of organically modified clay mineral polymer nanocomposites (CPN due to intercalation of organophilic montmorillonite by rubber matrix. The morphology of the blends became homogeneous and smoother with the presence of exofoliated/intercalated organically modified montmorillonite. Organomodified layered silicate sheets of montmorillonite greatly enhanced barrier properties by creating tortuous path that retarded the progress of solvent molecules through rubber matrix.

  3. Synthesis of poly(furfuryl alcohol)/montmorillonite nanocomposites ...

    Indian Academy of Sciences (India)

    The purpose of this study was to obtain poly(furfuryl alcohol) nanocomposites with Algerian organically modified clay (termed 12-montmorillonite). The formation of poly(furfuryl alcohol) was confirmed by infrared spectroscopy (IR); the prepared nanocomposites were characterized by X-ray diffraction (XRD), transmission ...

  4. Effect of montmorillonite on arsenic accumulation in common carp

    African Journals Online (AJOL)

    Yomi

    2012-02-01

    Feb 1, 2012 ... The effect of montmorillonite (MMT) on dietary arsenic (As(III)) accumulation in tissues of common carp ..... by clay minerals has been primarily attributed to the .... Trace elements (Cu or Zn) concentration in sampled tissues of common carp after .... interactions among mixtures of lead, cadmium and arsenic.

  5. Characterization and Identification of Bituminous Materials Modified with Montmorillonite Nanoclay

    NARCIS (Netherlands)

    Liu, G.

    2011-01-01

    Montmorillonite (Mt) nanoclay is a layered silicate mineral with a 2:1-type layer structure, two tetrahedrals sandwiching one octahedral. In recent decades, it is successfully introduced into polymer systems to form polymer-clay nanocomposites (PCN) in which the silicate layers of the Mt are

  6. 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

  7. Tailoring the mechanical properties of SU-8/clay nanocomposites: polymer microcantilever fabrication perspective

    CSIR Research Space (South Africa)

    Chen, H

    2014-03-01

    Full Text Available SU-8/Clay nanocomposite is considered as a candidate material for microcantilever sensor fabrication. Organically modified montmorillonite clay nanoparticles are dispersed in the universally used negative photoresist polymer SU-8, for a low cost...

  8. The Pressure-Volume-Temperature Equation of State of Iron-Rich (Mg,Fe)O

    Science.gov (United States)

    Wicks, J. K.; Jackson, J. M.; Zhuravlev, K. K.; Prakapenka, V.

    2012-12-01

    Seismic observations near the base of the core-mantle boundary (CMB) have detected 5-20 km thick patches in which the seismic wave velocities are reduced by up to 30%. These ultra-low velocity zones (ULVZs) have been interpreted as aggregates of partially molten material (e.g. Williams and Garnero 1996, Hernlund and Jellinek, 2010) or as solid, iron-enriched residues (e.g. Knittle and Jeanloz, 1991; Mao et al., 2006; Wicks et al., 2010), typically based on proposed sources of velocity reduction. The stabilities of these structure types have been explored through dynamic models that have assembled a relationship between ULVZ stability and density (Hernlund and Tackley, 2007; Bower et al., 2010). Now, to constrain the chemistry of ULVZs, more information is needed on the relationship between density and sound velocity of candidate phases. Recently, we have shown that the characteristically low sound speeds of ULVZs can be produced by small amounts of iron-rich (Mg,Fe)O, which is likely to be found in iron-rich assemblages based on current partitioning studies (eg. Sakai et al., 2010; Tange et al., 2009). We determined the Debye velocity (VD) of (Mg.1657Fe.84)O using nuclear resonant inelastic x-ray scattering (NRIXS), and calculated the seismically relevant compressional (VP) and shear (VS) wave velocities up to 120 GPa using an equation of state of a similar composition (Wicks et al., 2010). These densities and sound velocities, in turn, are consistent with reasonable morphologies of modeled solid ULVZs (Bower et al., 2011). To increase the accuracy of density and sound velocity predictions, measurements must be made at elevated temperatures to correctly predict the properties of iron-rich (Mg,Fe)O at mantle conditions. In this study, we present the pressure-volume-temperature equation of state of (Mg.0657Fe.94)O measured up to pressures of 120 GPa and temperatures of 2000 K. Volume was measured with x-ray diffraction at beamline 13-ID-D of the Advanced Photon

  9. 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.

  10. Crystallization characteristics of iron-rich glass ceramics prepared from nickel slag and blast furnace slag

    Science.gov (United States)

    Wang, Zhong-Jie; Ni, Wen; Li, Ke-Qing; Huang, Xiao-Yan; Zhu, Li-Ping

    2011-08-01

    The crystallization process of iron-rich glass-ceramics prepared from the mixture of nickel slag (NS) and blast furnace slag (BFS) with a small amount of quartz sand was investigated. A modified melting method which was more energy-saving than the traditional methods was used to control the crystallization process. The results show that the iron-rich system has much lower melting temperature, glass transition temperature ( T g), and glass crystallization temperature ( T c), which can result in a further energy-saving process. The results also show that the system has a quick but controllable crystallization process with its peak crystallization temperature at 918°C. The crystallization of augite crystals begins from the edge of the sample and invades into the whole sample. The crystallization process can be completed in a few minutes. A distinct boundary between the crystallized part and the non-crystallized part exists during the process. In the non-crystallized part showing a black colour, some sphere-shaped augite crystals already exist in the glass matrix before samples are heated to T c. In the crystallized part showing a khaki colour, a compact structure is formed by augite crystals.

  11. Modification of montmorillonite with alkyltrimethylammonium bromides. Effect of thermal and ultrasonic treatment upon the structure of montmorillonite

    International Nuclear Information System (INIS)

    Rodriguez M, F.J.; Galotto Lopez, M.J.; Guarda M, A.

    2009-01-01

    The aim of this work was synthesized organo clays using different methodologies oriented to improve the cationic interchange between montmorillonite and organic salts. Thermal and thermal-ultrasonic methods were studied. According to obtained results, the ultrasonic application improved the interchange between organic ammonium and sodium ion of the clay. On the other hand, an important effect of molecular weight of organic surfactant was observed. Formation of organo clays was evidenced through ray-X diffraction (RXD), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). (author)

  12. THE SYNTHESIS OF Cr2O3-PILLARED MONTMORILLONITE (CrPM AND ITS USAGE FOR HOST MATERIAL OF p-NITROANILINE

    Directory of Open Access Journals (Sweden)

    Karna Wijaya

    2010-06-01

    Full Text Available The synthesis of Cr2O3-pillared montmorillonite (CrPM and its usage for host material of p-nitroaniline have been conducted. The Cr2O3-pillared montmorillonite clays was prepared by a direct ion exchange method. First, the polyhydroxychromium as a pillaring spesies was intercalated into the interlayer region of the montmorillonite clays (purified clay in the monocation form, result in a montmorillonite-polyoxychromium intercalation compound. The precursors/pillaring spesies was not stable, hence it must be stabilized by calcination in order to transform the polyoxychromium via dehydration and dehydroxylation processes into Cr2O3. This oxide constituts the so-called pillar that prop the clay layers apart to a relatively large distance. The Cr2O3-pillared clays as a host material was added into ethanol solution saturated with p-nitroaniline, and mixture was stirred for 24 h at room temperature. The Na-montmorillonite, Cr2O3-pillared clay and p-nitroaniline-Cr2O3-pillared clay (pNA-CrPM were characterized by X-Ray Diffraction (XRD, Gas Sorption Analysis, Infrared Spectroscopy (FTIR and Activated Neutron Analysis (ANA methods. The result of research showed that basal spacing (d001 of Cr2O3-pillared montmorillonite (CrPM was 18,55 Å, meanwhile the basal spacing of the hydrated Na-montmorillonite was 14,43 Å. The specific surface area of the Cr2O3-pillared montmorillonite was 174,308 m2/g, whereas p-nitroaniline-Cr2O3-pillared clay (pNA-CrPM was 133,331641 m2/g. This fact indicated that p-nitroaniline has been included into the pore of the Cr2O3-pillared clay.   Keyword: montmorillonite, pillared-clay, ion exchange, intercalate.

  13. Unique morphology of dispersed clay particles in a polymer nanocomposite

    CSIR Research Space (South Africa)

    Malwela, T

    2011-02-01

    Full Text Available This communication reports a unique morphology of dispersed clay particles in a polymer nanocomposite. A nanocomposite of poly[butylene succinate)-co-adipate] (PBSA) with 3 wt% of organically modified montmorillonite was prepared by melt...

  14. ANALYSIS DEGRADATION OF POLYSTYRENE WITH MONTMORILLONITE NANOFILLERS

    Directory of Open Access Journals (Sweden)

    Maria Mihalikova

    2014-01-01

    Full Text Available The paper is focused on the experimental investigation of the montmorillonite nanofillers effect on deformation properties of polystyrene KRASTEN 171. In some cases, combination of a low amount of clay with dispersed polymeric phase may cause synergistic effects leading to very fair balance of mechanical behaviour. This seems to be a consequence of complex influencing the multiphase system by clay such as modification of components (reinforcement and parameters of the interface accompanied by influencing the dynamic phase behaviour, i.e., the compactibilizing effect. The paper analyses the effect of nanocomposites and type of the material on the individual measured parameters, relations between them, strength and deformation behaviour. Deformation was evaluated by non-contact videoextensometry method

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

    International Nuclear Information System (INIS)

    Tsiao, C.; Carrado, K.A.

    1990-01-01

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

  16. Preparation of Polypropylene/Montmorillonite Nanocomposites Using Ionizing Radiation

    International Nuclear Information System (INIS)

    Güven, Olgun; Zengin, Fatma

    2011-01-01

    Polymer/clay nanocomposites are new generation materials that bring significant changes in mechanical, thermal and permeation properties of base polymers by low clay loading. In this study, polypropylene/montmorillonite nanocomposites were prepared by melt intercalation method by using batch type mixer. Two polypropylene samples with different melt flow indexes are used as the matrix, maleic anhydride grafted polypropylene (PP-g-MAH), and polypropylene granules oxidized by radiation/ozone are used as compatibilizer and unmodified clay (Na + montmorillonite, MMT) as the filler. Aim of this study is to examine the effect of different compatibilizers in the mechanical properties of polypropylene composite. Firstly, PP/clay samples were prepared and the effect of clay was examined, then 5, 10, 20kGy oxidized/degraded polypropylenes were used as compatibilizer and, 10 kGy was determined to be the most suitable irradiation dose for the best compatibilizing effect. Polypropylene granules were ozonated until they contained carbonyl groups equivalent to 10kGy oxidized PP, which was checked by FTIR-ATR spectroscopy. UV-visible reflectance measurements were also made on film samples and no significant changes were observed in visible region. Nano structures of some nanocomposites were characterized by PALS (Positron Annihilation Lifetime Spectroscopy) where it was observed that the addition of clay decreased the number of free volume holes and free volume hole radia. The dispersion state of MMT within polymer matrix was analyzed by XRD (X-ray diffraction). Tensile tests were made and the effect of the addition of clay and compatibilizers investigated. At low melt flow index PP, 1% MMT of PP/10kGyPP/MMT nanocomposite showed an increase in E-modulus 26% and in tensile strength 8% as compared to those of pristine PP. In conclusion radiation degraded (chain scissioned and oxidized) PP has been found to show very good compatibilizing effect for the natural montmorillonite

  17. Preparation of Polypropylene/Montmorillonite Nanocomposites Using Ionizing Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Güven, Olgun; Zengin, Fatma

    2011-07-01

    Polymer/clay nanocomposites are new generation materials that bring significant changes in mechanical, thermal and permeation properties of base polymers by low clay loading. In this study, polypropylene/montmorillonite nanocomposites were prepared by melt intercalation method by using batch type mixer. Two polypropylene samples with different melt flow indexes are used as the matrix, maleic anhydride grafted polypropylene (PP-g-MAH), and polypropylene granules oxidized by radiation/ozone are used as compatibilizer and unmodified clay (Na{sup +} montmorillonite, MMT) as the filler. Aim of this study is to examine the effect of different compatibilizers in the mechanical properties of polypropylene composite. Firstly, PP/clay samples were prepared and the effect of clay was examined, then 5, 10, 20kGy oxidized/degraded polypropylenes were used as compatibilizer and, 10 kGy was determined to be the most suitable irradiation dose for the best compatibilizing effect. Polypropylene granules were ozonated until they contained carbonyl groups equivalent to 10kGy oxidized PP, which was checked by FTIR-ATR spectroscopy. UV-visible reflectance measurements were also made on film samples and no significant changes were observed in visible region. Nano structures of some nanocomposites were characterized by PALS (Positron Annihilation Lifetime Spectroscopy) where it was observed that the addition of clay decreased the number of free volume holes and free volume hole radia. The dispersion state of MMT within polymer matrix was analyzed by XRD (X-ray diffraction). Tensile tests were made and the effect of the addition of clay and compatibilizers investigated. At low melt flow index PP, 1% MMT of PP/10kGyPP/MMT nanocomposite showed an increase in E-modulus 26% and in tensile strength 8% as compared to those of pristine PP. In conclusion radiation degraded (chain scissioned and oxidized) PP has been found to show very good compatibilizing effect for the natural montmorillonite

  18. Synthesis of Poly aniline-Montmorillonite Nano composites Using H2O2 as the Oxidant

    International Nuclear Information System (INIS)

    Binitha, N.; Binitha, N.; Suraja, V.; Zahira Yaakob; Sugunan, S.

    2011-01-01

    Poly aniline montmorillonite nano composite was prepared using H 2 O 2 as the oxidant. The catalytic environment of montmorillonite favours polymerization. Intercalation and composite formation was proven from various techniques such as XRD, FTIR, DRS and thermal analysis. XRD patterns give the dimension of the intercalated PANI, from the shift of 2θ values, which is in the nano range. FTIR showed that PANI composite formation occurred without affecting the basic clay layer structure. Thus the successful development of an alternative cheap route for poly aniline-montmorillonite nano composite was well established. (author)

  19. Preparation and Characterization of Phenolic Resin/Montmorillonite Nanocomposite

    Directory of Open Access Journals (Sweden)

    Morteza Soltan-Dehghan

    2012-12-01

    Full Text Available Phenolic resins have been widely used for selective high technology applications due to their excellent ablative properties, structural integrity and thermal stability that make them appropriate for thermal insulation materials, wood products industry, coatings, moulding compounds and composite materials. Polymer layered silicate nanocomposites based on montmorillonite (MMT have attracted a great deal of attention because of enhanced properties in mechanical, thermal, barrier and clarity properties without a significant increase in density, which is not possible with conventional fillers. Phenolic resin/montmorillonite (Cloisite 15A nanocomposite was prepared by a combined route of solution blending and in-situ polymerization. Theoptimized conditions for preparation of nanocomposite were achieved by evaluation of various processing parameters (mechanical mixer, high speed disperser and high energy ultrasonic source, mixing time (0.5, 1, 3, 10, 24, 48, 72, and 96 h and different amounts of montmorillonite (5 and 10 weight percents of montmorillonite relative to resol. X-Ray Diffractometer and thermal gravimetric analyzer were used accordingly to show the degree of nanodispersions of organomontmorillonite in polymeric matrix and the effect of nanofiller on thermal stability of nanocomposite with respect to neatresol. The results of high energy ultrasonic source show that a nanocomposite of phenolic resin with 5 wt% montmorillonite displays the best dispersion of clay layers. Thermal stability of nanocomposite was increased by 27% in comparison with neat resol.

  20. Effects of humidity and interlayer cations on the frictional strength of montmorillonite

    Science.gov (United States)

    Tetsuka, Hiroshi; Katayama, Ikuo; Sakuma, Hiroshi; Tamura, Kenji

    2018-04-01

    We developed a humidity control system in a biaxial friction testing machine to investigate the effect of relative humidity and interlayer cations on the frictional strength of montmorillonite. We carried out the frictional experiments on Na- and Ca-montmorillonite under controlled relative humidities (ca. 10, 30, 50, 70, and 90%) and at a constant temperature (95 °C). Our experimental results show that frictional strengths of both Na- and Ca-montmorillonite decrease systematically with increasing relative humidity. The friction coefficients of Na-montmorillonite decrease from 0.33 (at relative humidity of 10%) to 0.06 (at relative humidity of 93%) and those of Ca-montmorillonite decrease from 0.22 (at relative humidity of 11%) to 0.04 (at relative humidity of 91%). Our results also show that the frictional strength of Na-montmorillonite is higher than that of Ca-montmorillonite at a given relative humidity. These results reveal that the frictional strength of montmorillonite is sensitive to hydration state and interlayer cation species, suggesting that the strength of faults containing these clay minerals depends on the physical and chemical environment.[Figure not available: see fulltext.

  1. Effect of milling time on the structure, particle size, and morphology of montmorillonite

    International Nuclear Information System (INIS)

    Abareshi, M.

    2017-01-01

    In the current research, effect of milling on the structure, particle size and morphology of montmorillonite was investigated. For this purpose, the montmorillonite was analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Then the montmorillonite was milled using high energy planetary ball mill at different milling times (1-60 hours). After that, the structure, particle size and morphology of all samples were investigated by XRD, FTIR, SEM, and transmission electron microscopy. Results showed that the ball milling causes the particle size reduction of clay and separation of the clay layers. Moreover, ball milling increases the overall structural disorder and transforms the crystalline structure into an amorphous phase. Also, the morphology of clay particle changes from layered to aggregates of almost rounded particles after 60 hours of milling.

  2. Electrolyte diffusion in compacted montmorillonite engineered barriers

    International Nuclear Information System (INIS)

    Jahnke, F.M.; Radke, C.J.

    1985-09-01

    The bentonite-based engineered barrier or packing is a proposed component of several designs conceived to dispose of high-level nuclear waste in geologic repositories. Once radionuclides escape the waste package, they must first diffuse through the highly impermeable clay-rich barrier before they reach the host repository. To determine the effectiveness of the packing as a sorption barrier in the transient release period and as a mass-transfer barrier in the steady release period over the geologic time scales involved in nuclear waste disposal, a fundamental understanding of the diffusion of electrolytes in compacted clays is required. We present, and compare with laboratory data, a model quantifying the diffusion rates of cationic cesium and uncharged tritium in compacted montmorillonite clay. Neutral tritium characterizes the geometry (i.e., tortuosity) of the particulate gel. After accounting for cation exchange, we find that surface diffusion is the dominant mechanism of cation transport, with an approximate surface diffusion coefficient of 2 x 10 -6 cm 2 /s for cesium. This value increases slightly with increasing background ionic strength. The implications of this work for the packing as a migration barrier are twofold. During the transient release period, K/sub d/ values are of little importance in retarding ion migration. This is because sorption also gives rise to a surface diffusion path, and it is surface diffusion which controls the diffusion rate of highly sorbing cations in compacted montmorillonite. During the steady release period, the presence of surface diffusion leads to a flux through the packing which is greatly enhanced. In either case, if surface diffusion is neglected, the appropriate diffusion coefficient of ions in compacted packing will be in considerable error relative to current design recommendations. 11 refs., 4 figs., 1 tab

  3. Characterization of poly pyrrole/montmorillonite electro polymerised onto Pt

    International Nuclear Information System (INIS)

    Castagno, K.R.L.; Azambuja, D.S.; Dalmoro, V.; Mauller, R.S.

    2010-01-01

    In this study films of polypyrrole/montmorillonite (PPy/MT) were electropolymerized on platinum in order to evaluate the performance of this technique in the preparation of nanocomposite materials and to determine the thermal properties and conductivity of the composites. The films were synthesized from a solution containing pyrrole, dodecylbenzene sulfonate, acid and two types of clays: montmorillonite-Na + (MT-Na) and montmorillonite-30B (MT-M). The characterization of the films we have used FT-IR, TEM, XRD, TGA, DSC and resistivity measurement by the four-point van der Pauw method. The study showed that the adopted method of exfoliation and the electropolymerization method used, allows obtaining nanocomposite materials. Analyses of FT-IR, TEM and XRD show that the clays are exfoliated in the polymer matrix. Thermal analysis of the films indicates that the addition of clay reflects an enhancement in the thermal properties of the matrix of PPy, but decreases the conductivity of the same. (author)

  4. Clay-based materials for engineered barriers: a review

    International Nuclear Information System (INIS)

    Lajudie, A.; Raynal, J.; Petit, J.C.; Toulhoat, P.

    1994-01-01

    The potential importance of backfilling and plugging in underground radioactive waste repositories has led different research institutions to carry out extensive studies of swelling clay materials for the development of engineered barriers in underground conditions. These materials should combine a variety of hydro-thermo-mechanical and geochemical properties: impermeability, swelling ability in order to fill all void space, heat transfer and retention capacity for the most noxious radionuclides. Smectite clays best exhibit these properties and most of the research effort has been devoted to this type of materials. In this paper, mineralogical composition, sodium or calcium content, thermo-hydro-mechanical properties, swelling pressure, hydraulic and thermal conductivity, and chemical properties of five smectite clays selected by five major nuclear countries are reviewed: Avonseal montmorillonite (Canada), MX 80 montmorillonite (Sweden), Montigel montmorillonite (Switzerland), S-2 montmorillonite (Spain), and Fo-Ca inter stratified kaolinite/beidellite (France). (J.S.). 29 refs., 5 figs., 3 tabs

  5. Montmorillonite stability. With special respect to KBS-3 conditions

    International Nuclear Information System (INIS)

    Karnland, Ola; Birgersson, Martin

    2006-08-01

    The basic advantageous properties, e.g. low hydraulic conductivity and high swelling pressure, of the bentonite buffer in a KBS- repository stem from a strong interaction between water and the montmorillonite mineral in the bentonite. Minerals similar in structure but with substantially lower mineral-water interaction exist in nature. Transformations from montmorillonite to such minerals are observed e.g. in burial diagenesis and in contact metamorphism. A thermodynamic consideration confirms that medium and low charged montmorillonite is not in chemical equilibrium with quartz. From a safety assessment perspective it is therefore of vital importance to quantify the montmorillonite transformation under KBS- conditions. Silica release from the montmorillonite tetrahedral layers is the initial process for several possible transformations. Replacement of silica by aluminum increases the layer charge but maintains the basic atomic structure. A sufficiently high layer charge results in an irreversible collapse of the clay-water structure, i.e. a non-swelling mineral is formed. Compared to other cations, potassium as counter ion leads to a collapse at lower layer charge and the produced phase is generally termed illite. Montmorillonite-to-illite transformation is the most frequently found alteration process in nature. Three different kinetic illitization models are reviewed and the model proposed by Huang et al. is considered the most suitable for quantification in a KBS- repository, since the kinetic rate expression and its associated parameters are systematically determined by laboratory work. The model takes into account temperature, montmorillonite fraction and potassium concentration, but do not include relevant parameters such as pH, temperature gradients and water content. Calculations by use of the Huang illitization model applied for repository conditions yield insignificant montmorillonite transformation also under very pessimistic assumptions. Other non

  6. Montmorillonite stability. With special respect to KBS-3 conditions

    Energy Technology Data Exchange (ETDEWEB)

    Karnland, Ola; Birgersson, Martin [Clay Technology AB, Lund (Sweden)

    2006-08-15

    The basic advantageous properties, e.g. low hydraulic conductivity and high swelling pressure, of the bentonite buffer in a KBS- repository stem from a strong interaction between water and the montmorillonite mineral in the bentonite. Minerals similar in structure but with substantially lower mineral-water interaction exist in nature. Transformations from montmorillonite to such minerals are observed e.g. in burial diagenesis and in contact metamorphism. A thermodynamic consideration confirms that medium and low charged montmorillonite is not in chemical equilibrium with quartz. From a safety assessment perspective it is therefore of vital importance to quantify the montmorillonite transformation under KBS- conditions. Silica release from the montmorillonite tetrahedral layers is the initial process for several possible transformations. Replacement of silica by aluminum increases the layer charge but maintains the basic atomic structure. A sufficiently high layer charge results in an irreversible collapse of the clay-water structure, i.e. a non-swelling mineral is formed. Compared to other cations, potassium as counter ion leads to a collapse at lower layer charge and the produced phase is generally termed illite. Montmorillonite-to-illite transformation is the most frequently found alteration process in nature. Three different kinetic illitization models are reviewed and the model proposed by Huang et al. is considered the most suitable for quantification in a KBS- repository, since the kinetic rate expression and its associated parameters are systematically determined by laboratory work. The model takes into account temperature, montmorillonite fraction and potassium concentration, but do not include relevant parameters such as pH, temperature gradients and water content. Calculations by use of the Huang illitization model applied for repository conditions yield insignificant montmorillonite transformation also under very pessimistic assumptions. Other non

  7. Feasibility of sulfide control in sewers by reuse of iron rich drinking water treatment sludge.

    Science.gov (United States)

    Sun, Jing; Pikaar, Ilje; Sharma, Keshab Raj; Keller, Jürg; Yuan, Zhiguo

    2015-03-15

    Dosage of iron salt is the most commonly used method for sulfide control in sewer networks but incurs high chemical costs. In this study, we experimentally investigate the feasibility of using iron rich drinking water treatment sludge for sulfide control in sewers. A lab-scale rising main sewer biofilm reactor was used. The sulfide concentration in the effluent decreased from 15.5 to 19.8 mgS/L (without dosing) to below 0.7-2.3 mgS/L at a sludge dosing rate achieving an iron to total dissolved inorganic sulfur molar ratio (Fe:S) of 1:1, with further removal of sulfide possible by prolonging the reaction time. In fact, batch tests revealed an Fe consumption to sulfide removal ratio of 0.5 ± 0.02 (mole:mole), suggesting the possible occurrence of other reactions involving the removal of sulfide. Modelling revealed that the reaction between iron in sludge and sulfide has reaction orders of 0.65 ± 0.01 and 0.77 ± 0.02 with respect to the Fe and sulfide concentrations, respectively. The addition of sludge slightly increased the total chemical oxidation demand (tCOD) concentration (by approximately 12%) as expected, but decreased the soluble chemical oxidation demand (sCOD) concentration and methane formation by 7% and 20%, respectively. Some phosphate removal (13%) was also observed at the sludge dosing rate of 1:1 (Fe:S), which is beneficial to nutrient removal from the wastewater. Overall, this study suggests that dosing iron-rich drinking water sludge to sewers could be an effective strategy for sulfide removal in sewer systems, which would also reduce the sludge disposal costs for drinking water treatment works. However, its potential side-effects on sewer sedimentation and on the wastewater treatment plant effluent remain to be investigated. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. 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.

  9. Genotoxicity of unmodified and organo-modified montmorillonite

    DEFF Research Database (Denmark)

    Sharma, Anoop Kumar; Schmidt, Bjørn; Frandsen, Henrik Lauritz

    2010-01-01

    absent in the filtered samples, which was independently confirmed by dynamic light-scattering measurements. Detection and identification of free quaternary ammonium modifier in the filtered sample was carried out by HPLC-Q-TOF/MS and revealed a total concentration of a mixture of quaternary ammonium...... assay, none of the clays produced ROS in a cell-free test system (the DCFH-DA assay). Inductively coupled plasma mass-spectrometry (ICP-MS) was used to detect clay particles in the filtered samples using aluminium as a tracer element characteristic to clay. The results indicated that clay particles were...... analogues of 1.57 mu g/ml. These findings suggest that the genotoxicity of organo-modified montmorillonite was caused by the organo-modifier. The detected organo-modifier mixture was synthesized and comet-assay results showed that the genotoxic potency of this synthesized organo-modifier was in the same...

  10. ARSENIC ADSORPTION AND REDUCTION IN IRON-RICH SOILS NEARBY LANDFILLS IN NORTHWEST FLORIDA

    Directory of Open Access Journals (Sweden)

    Hongqin Xue

    2016-01-01

    Full Text Available In Florida, soils are mainly composed of Myakka, an acid soil characterized by a subsurface accumulation of humus and Al(III and Fe(III oxides. Downgradient of the landfills in Northwest Florida, elevated levels of iron and arsenic observations had been made in the groundwater from monitoring wells, which was attributed to the geomicrobial iron and arsenic reduction. There is thus an immediate research need for a better understanding of the reduction reactions that are responsible for the mobilization of iron and arsenic in the subsurface soil nearby landfills. Owing to the high Fe(III oxide content, As(V adsorption reactions with Fe(III oxide surfaces are particularly important, which may control As(V reduction. This research focused on the investigation of the biogeochemical processes of the subsurface soil nearby landfills of Northwest Florida. Arsenic and iron reduction was studied in batch reactors and quantified based on Monod-type microbial kinetic growth simulations. As(V adsorption in iron-rich Northwest Floridian soils was further investigated to explain the reduction observations. It was demonstrated in this research that solubilization of arsenic in the subsurface soil nearby landfills in Northwest Florida would likely occur under conditions favoring Fe(III dissimilatory reduction.

  11. Microstructural characterization of the geopolymer obtained from iron-rich metakaolin

    International Nuclear Information System (INIS)

    Vassalo, Erica Antunes de S.; Aguilar, Maria Teresa P.; Gumieri, Adriana Guerra

    2014-01-01

    Geopolymer is a material derived from precursors rich in SiO_2 and Al_2O_3, activated in an alkaline solution by means of a polymerization process. In this process, units of tetrahedral aluminosilicate structures are organized in repetitions that share oxygen. One of the precursors most commonly used to obtain geopolymer is metakaolin. Recent studies have reported iron enhancement in a partial replacement of the aluminium present in metakaolin. This paper presents the microstructural characterization and analysis of a geopolymer obtained by means of the activation of iron-rich metakaolin with sodium hydroxide at 12, 15 and 18 mol, both at room temperature and in an oven at 85±3°C. The geopolymers obtained were classified and analysed using X-ray fluorescence testing (EDX-720), a scanning electron microscope (SEM) and a Fourier transform infrared spectroscopy (FTIR). The results enabled an assessment of their physical-chemical and microstructural characteristics, as well as their reactive potential. (author)

  12. Phase composition of iron-rich R-Fe-Si (R=Dy, Ho, Er) alloys

    International Nuclear Information System (INIS)

    Ivanova, G.V.; Makarova, G.M.; Shcherbakova, E.V.; Belozerov, E.V.

    2005-01-01

    Phase composition is studied in iron-rich alloys of R-Fe-Si (R=Dy, Ho, Er). In the as-cast state R 2 (Fe, Si) 17 of type Th 2 Ni 17 and R(Fe, Si) 12 compounds are observed; in the alloys of rated composition of R(Fe 0.85 Si 0.15 ) 8.5 (R=Dy, Er) a compound R 2 (Fe, Si) 17 of Th 2 Zn 17 -type is revealed as well. The annealing at 1273 K results in formation of Dy 3 (Fe, Si) 29 and also the compounds with the presumed composition of Dy 4 (Fe, Si) 41 and Ho 4 (Fe, Si) 41 . As this takes place the alloys contain a transition structure as well that represents a set of small-sized areas with various type short-range order in mutual displacement of Fe-Fe(Si) dumpbell chains. The process of phase formation at 1273 K is faced with difficulties. Even the annealing for 1000 h does not result in the state of equilibrium [ru

  13. Very low sound velocities in iron-rich (Mg,Fe)O: Implications for the core-mantle boundary region

    International Nuclear Information System (INIS)

    Wicks, J.K.; Jackson, J.M.; Sturhahn, W.

    2010-01-01

    The sound velocities of (Mg .16 Fe .84 )O have been measured to 121 GPa at ambient temperature using nuclear resonant inelastic x-ray scattering. The effect of electronic environment of the iron sites on the sound velocities were tracked in situ using synchrotron Moessbauer spectroscopy. We found the sound velocities of (Mg .16 Fe .84 )O to be much lower than those in other presumed mantle phases at similar conditions, most notably at very high pressures. Conservative estimates of the effect of temperature and dilution on aggregate sound velocities show that only a small amount of iron-rich (Mg,Fe)O can greatly reduce the average sound velocity of an assemblage. We propose that iron-rich (Mg,Fe)O be a source of ultra-low velocity zones. Other properties of this phase, such as enhanced density and dynamic stability, strongly support the presence of iron-rich (Mg,Fe)O in localized patches above the core-mantle boundary.

  14. Dietary Intake of Iron Rich Food and Awareness on Iron Deficiency Anaemia among Female Students in Rawalpindi

    International Nuclear Information System (INIS)

    Siddiqui, F. R.; Usmani, A. Q.; Shahid, A.; Sadiq, T.

    2013-01-01

    Objective: To assess the awareness and intake of iron rich diet amongst college girls with a particular focus on the knowledge about the iron deficiency anaemia. Materials and Methods: A cross sectional survey was conducted in Government College for Women Rawalpindi, during September - December 2010. One hundred and thirty five students of intermediate level aged 17-19 years were selected through convenient sampling technique. The sample size was calculated by WHO-sample size calculator, keeping 95 percent Cl, p<0.05 statistically significant, anticipated population proportion of iron deficiency anaemia 35 percent and absolute precision at 0.08. Results: The awareness about iron rich diet and iron deficiency anaemia was satisfactory (86 percent), while poor intake of iron rich diet amongst adolescent college girls (52 percent) was found. About 65 percent of the participants had knowledge about the causes of iron deficiency anaemia (IDA); while 72 percent and 80 percent knew about the prevention and treatment of IDA respectively. Conclusions: Results indicate the gap between knowledge and practices about IDA; it highlights the need of an effective health promotional programme to raise awareness about the significance of iron in young female diet and to highlight the consequences when it is absent. (author)

  15. Preparation of organophilic clays and polypropylene nano composites

    International Nuclear Information System (INIS)

    Lima, Martha Fogliato S.; Nascimento, Vinicius G. do; Lenz, Denise M.; Schenato, Flavia

    2011-01-01

    Polypropylene/montmorillonite nano composites were prepared by the melt intercalation technique. The clay was organically modified with different quaternary ammonium salts to obtain the organo clay. The modified clays with the quaternary ammonium salts were introduced in a polypropylene matrix with 3 wt. % of clay. The interlayer distance (d001) of the clay particles were obtained by X- ray diffraction and the thermal stability of the systems were investigated by thermogravimetry. The organo clay presence in the polymer matrix increased the degradation temperature in relation to the pure polymer. (author)

  16. Diatoms in acid mine drainage and their role in the formation of iron-rich stromatolites

    Energy Technology Data Exchange (ETDEWEB)

    Brake, S.S.; Hasiotis, S.T.; Dannelly, H.K. [Indiana State University, Terre Haute, IN (United States)

    2004-08-01

    Adverse conditions in the acid mine drainage (AMD) system at the Green Valley mine, Indiana, limit diatom diversity to one species, Nitzschia tubicola. It is present in three distinct microbial consortia: Euglena mutabilis-dominated biofilm, diatom-dominated biofilm, and diatom-exclusive biofilm. E. mutabilis dominates the most extensive biofilm, with lesser numbers of N. tubicola, other eukaryotes, and bacteria. Diatom-dominated biofilm occurs as isolated patches containing N. tubicola with minor fungal hyphae, filamentous algae, E. mutabilis, and bacteria. Diatom-exclusive biofilm is rare, composed entirely of N. tubicola. Diatom distribution is influenced by seasonal and intraseasonal changes in water temperature and chemistry. Diatoms are absent in winter due to cool water temperatures. In summer, isolated patchy communities are present due to warmer water temperatures. In 2001, the diatom community expanded its distribution following a major rainfall that temporarily diluted the effluent, creating hospitable conditions for diatom growth. After several weeks when effluent returned to preexisting conditions, the diatom biofilm retreated to isolated patches, and E. mutabilis biofilm flourished. Iron-rich stromatolites underlie the biofilms and consist of distinct laminae, recording spatial and temporal oscillations in physicochemical conditions and microbial activity. The stromatolites are composed of thin, wavy laminae with partially decayed E. mutabilis biofilm, representing microbial activity and iron precipitation under normal AMD conditions. Alternating with the wavy layers are thicker, porous, spongelike laminae composed of iron precipitated on and incorporated into radiating colonies of diatoms. These layers indicate episodic changes in water chemistry, allowing diatoms to temporarily dominate the system.

  17. Controlled swelling and adsorption properties of polyacrylate/montmorillonite composites

    Energy Technology Data Exchange (ETDEWEB)

    Natkanski, Piotr [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Kustrowski, Piotr, E-mail: kustrows@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Bialas, Anna; Piwowarska, Zofia [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Michalik, Marek [Institute of Geological Sciences, Jagiellonian University, Oleandry 2a, 30-063 Krakow (Poland)

    2012-10-15

    A series of novel polyacrylate/montmorillonite composites was synthesized by in situ polymerization in aqueous slurry of clay. Dissociated (obtained by adding ammonium or sodium hydroxide) and undissociated forms of acrylic acid were used as monomers in the hydrogel synthesis. The structure and composition of the samples were studied by powder X-ray diffraction, diffuse reflectance infra-red Fourier transform spectroscopy, thermogravimetry and elemental analysis. It has been found that the kind of monomer influences strongly the location of a polymer chain in the formed composite. Complete intercalation of hydrogel into the interlayer space of montmorillonite was observed for sodium polyacrylate, whereas polyacrylic acid and ammonium polyacrylate mainly occupied the outer surface of the clay. The position of hydrogel determined the swelling and adsorption properties of the studied composites. The important factor influencing the kinetics of Fe(III) cation adsorption was pH. The analysis of adsorption isotherms allowed to propose the mechanism of Fe(III) cation adsorption. Highlights: Black-Right-Pointing-Pointer Polyacrylate hydrogels can be introduced into the interlayers of clay. Black-Right-Pointing-Pointer The position of hydrogel in the composite depends on the polymer type. Black-Right-Pointing-Pointer Ammonium polyacrylate places outside the clay, sodium one is intercalated into it. Black-Right-Pointing-Pointer Swelling and adsorption capacities can be controlled by the polymer position. Black-Right-Pointing-Pointer High adsorption efficiency in Fe(III) removal was observed.

  18. Behind adhesion of uranyl onto montmorillonite surface: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Yang, W.; Zaoui, A., E-mail: azaoui@polytech-lille.fr

    2013-10-15

    Highlights: • We investigated the adsorption of uranyl onto Montmorillonite surface. • We studied the surface energy between layered Montmorillonite sheets. • We studied the work of adhesion between radionuclide and charged Montmorillonite. -- Abstract: We have performed molecular dynamics simulations to investigate the adsorption of radionuclide elements species onto substituted Montmorillonite (001) surface in the presence of different counterions. The structure and the dynamics of uranyl ion as well as its aquo, chloride ion, and carbonate complexes are analyzed. In addition, we have studied the surface energy between layered Montmorillonite sheets and the work of adhesion between radionuclide and charged Montmorillonite. The clay model used here is a Wyoming-type Montmorillonite with 0.75e negative charge per unit cell resulting from substitutions in Octahedral and Tetrahedral sheets. The system model was constructed based on CLAYFF force field potential model. To evaluate the thermodynamic work of adhesion, each surface and clay layer regions are converted to a thin film model. One and two species of radionuclide elements (UO{sub 2}(H{sub 2}O){sub 5},UO{sub 2}CO{sub 3}(H{sub 2}O){sub 5}, and UO{sub 2}Cl{sub 2}(H{sub 2}O){sub 5}) were deposited near the clay surface in a pseudo-two-dimensional periodic cell. Analysis shows that the uranyl ion structure is preserved with two axial oxygen atoms detected at 1.8 Å. Radial distribution functions results indicate that average U-O{sub w} distances are 2.45–2.61 Å, and 2.29–2.40 Å for U-O{sub c} distance. Average U-Cl distances are 2.78–3.08 Å, which is relatively larger than that of Uranium atom-Oxygen atom because of electrostatic factors.

  19. Montmorillonite stability under near-field conditions

    Energy Technology Data Exchange (ETDEWEB)

    Leupin, O.X. (ed.); Birgersson, M.; Karnland, O. [Clay Technology AB, Lund (Sweden); Korkeakoski, P. [Posiva Oy, Eurajoki (Finland); Sellin, P. [Svensk Kärnbränslehantering AB, SKB, Stockholm (USSR); Mäder, U.; Wersin, P. [University of Berne, Berne (Switzerland)

    2014-07-15

    Clay-based engineered barriers comprising bentonite and bentonite/sand mixtures are the favoured option in geological repositories for high-level waste due to their inherently low hydraulic conductivity at full saturation. This ensures that diffusion of solutes such as radionuclides will be the dominating mechanism for transport through the engineered barriers. Another advantageous property of bentonite is the development of swelling pressure in contact with water under the constant volume conditions of repository excavations, ensuring the closure of unintentional gaps or openings. The predictability of the long-term behaviour of bentonite (up to a million years) is thus key to the safety analysis. The thermal pulse from the radioactive decay of the radionuclides in the high-level waste and spent fuel will lead to temperatures significantly higher than in the undisturbed host rock for hundreds of years, which may influence the thermodynamic stability and kinetics of alteration reactions of montmorillonite, the smectite that is the main constituent of the bentonite. The aim of this report is to review the present understanding of potential alteration of bentonite by focusing on experimental and modeling results under the thermal conditions of a repository. Many studies show that the transformation of smectite-to-illite is induced by increasing temperature and potassium activity. The conversion process is complex and still not completely understood. Nonetheless, it displays very slow kinetics over a wide range of environmental conditions for the temperatures of interest. The various models for illitisation of smectites suggest negligible transformation in a repository due to the relatively short period of elevated temperatures and slow mass transport. However, because of uncertainties and a number of conservatisms in the application of such models, the results of such calculations should be considered as bounding and indicative and not as quantitative predictions. In

  20. Montmorillonite stability under near-field conditions

    International Nuclear Information System (INIS)

    Leupin, O.X.; Korkeakoski, P.; Sellin, P.; Mäder, U.; Wersin, P.

    2014-07-01

    Clay-based engineered barriers comprising bentonite and bentonite/sand mixtures are the favoured option in geological repositories for high-level waste due to their inherently low hydraulic conductivity at full saturation. This ensures that diffusion of solutes such as radionuclides will be the dominating mechanism for transport through the engineered barriers. Another advantageous property of bentonite is the development of swelling pressure in contact with water under the constant volume conditions of repository excavations, ensuring the closure of unintentional gaps or openings. The predictability of the long-term behaviour of bentonite (up to a million years) is thus key to the safety analysis. The thermal pulse from the radioactive decay of the radionuclides in the high-level waste and spent fuel will lead to temperatures significantly higher than in the undisturbed host rock for hundreds of years, which may influence the thermodynamic stability and kinetics of alteration reactions of montmorillonite, the smectite that is the main constituent of the bentonite. The aim of this report is to review the present understanding of potential alteration of bentonite by focusing on experimental and modeling results under the thermal conditions of a repository. Many studies show that the transformation of smectite-to-illite is induced by increasing temperature and potassium activity. The conversion process is complex and still not completely understood. Nonetheless, it displays very slow kinetics over a wide range of environmental conditions for the temperatures of interest. The various models for illitisation of smectites suggest negligible transformation in a repository due to the relatively short period of elevated temperatures and slow mass transport. However, because of uncertainties and a number of conservatisms in the application of such models, the results of such calculations should be considered as bounding and indicative and not as quantitative predictions. In

  1. A study of the fixing of phosphoric ions by zirconium-montmorillonite; Etude de la fixation d'ions phosphoriques par la montmorillonite-zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Bittel, R; Boursat, C; Platzer, R [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    In connection with the research carried out on the purification of nuclear reactor water, we have undertaken a study of the ion-exchange properties of acid montmorillonite. In a previous paper, we described the preparation of zirconium-montmorillonite small plate. The present article aims to study some of the properties of the clay obtained. We have observed that zirconium-montmorillonite fixes very strongly the phosphorus from solutions of phosphoric acid or of phosphates: on 1 g of clay it is possible to fix 1,2 milli-atoms-gram of zirconium and the zirconium montmorillonite itself fixes 2,1 milli-atoms-gram of phosphorus. An explanation of these experimental results, which is as much chemical as mineralogical, is the hypothesis that the fixing of phosphoric ions modifies the distribution of the ions between the platelets and precipitates a very slightly soluble product of the type diphospho-zirconic acid. (author) [French] En rapport avec des recherches sur I'epuration de l'eau des reacteurs nucleaires nous avons entrepris une etude sur les proprietes d'echangeur d'ions de la montmorillonite-acide. Dans une precedente publication, nous avons decrit la preparation des plaquettes de montmorillonite-zirconium. La presente communication a pour but d'etudier quelques proprietes de l'argile obtenue. Nous avons constate que la montmorilionite-zirconium fixe le phosphore de solutions d'acide phosphorique ou de phosphate avec une grande intensite: sur 1 g d'argile, on peut fixer 1,2 atomes-gramme de zirconium, et la montmorillonite-zirconium fixe a son tour 2,1 milli-atomesgramme de phosphore. Une explication des resultats experimentaux, tant d'ordre chimique que d'ordre mineralogique, consiste en l'hypothese suivant laquelle la fixation d'ions phosphoriques modifierait la repartition des ions entre les feuillets avec precipitation du compose tres peu soluble (type: acide diphosphozirconique). (auteur)

  2. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chih-Jen [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan (China); Li, Zhaohui, E-mail: li@uwp.edu [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Department of Geosciences, University of Wisconsin - Parkside, Kenosha, WI 53144 (United States); Jiang, Wei-Teh, E-mail: atwtj@mail.ncku.edu.tw [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Jean, Jiin-Shuh; Liu, Chia-Chuan [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2010-11-15

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca{sup 2+} as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pK{sub a2} (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d{sub 001}) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water.

  3. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    International Nuclear Information System (INIS)

    Wang, Chih-Jen; Li, Zhaohui; Jiang, Wei-Teh; Jean, Jiin-Shuh; Liu, Chia-Chuan

    2010-01-01

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca 2+ as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pK a2 (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d 001 ) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water.

  4. Aflatoxin Toxicity Reduction in Feed by Enhanced Binding to Surface-Modified Clay Additives

    Science.gov (United States)

    Jaynes, William F.; Zartman, Richard E.

    2011-01-01

    Animal feeding studies have demonstrated that clay additives, such as bentonites, can bind aflatoxins in ingested feed and reduce or eliminate the toxicity. Bentonite deposits are found throughout the world and mostly consist of expandable smectite minerals, such as montmorillonite. The surfaces of smectite minerals can be treated with organic compounds to create surface-modified clays that more readily bind some contaminants than the untreated clay. Montmorillonites treated with organic cations, such as hexadecyltrimethylammonium (HDTMA) and phenyltrimethylammonium (PTMA), more effectively remove organic contaminants, such as benzene and toluene, from water than untreated clay. Similarly, montmorillonite treated with PTMA (Kd = 24,100) retained more aflatoxin B1 (AfB1) from aqueous corn flour than untreated montmorillonite (Kd = 944). Feed additives that reduced aflatoxin toxicity in animal feeding studies adsorbed more AfB1 from aqueous corn flour than feed additives that were less effective. The organic cations HDTMA and PTMA are considered toxic and would not be suitable for clay additives used in feed or food, but other non-toxic or nutrient compounds can be used to prepare surface-modified clays. Montmorillonite (SWy) treated with choline (Kd = 13,800) and carnitine (Kd = 3960) adsorbed much more AfB1 from aqueous corn flour than the untreated clay (Kd = 944). A choline-treated clay prepared from a reduced-charge, high-charge montmorillonite (Kd = 20,100) adsorbed more AfB1 than the choline-treated high-charge montmorillonite (Kd = 1340) or the untreated montmorillonite (Kd = 293). Surface-modified clay additives prepared using low-charge smectites and nutrient or non-toxic organic compounds might be used to more effectively bind aflatoxins in contaminated feed or food and prevent toxicity. PMID:22069725

  5. The nature of strong Brønsted acidity of Ni-SMM clay

    NARCIS (Netherlands)

    Yue, C.; Liu, C.; Mezari, B.; Brückner, A.; Pidko, E.A.; Rigutto, M.S.; Hensen, E.J.M.

    2016-01-01

    The origin of the high Brønsted acidity of Ni-SMM (Ni-substituted synthetic mica-montmorillonite; beidellite structure) clays was investigated. Ni-SMM clays with varying F content, SMM with F and Ni-SMM without F in the structure were synthesized under hydrothermal conditions. Ni-SMM clays with

  6. Use of the montmorillonite as crosslink agents for chitosan

    International Nuclear Information System (INIS)

    Barbosa, Rossemberg C.; Lima, Rosemary S. Cunha; Braga, Carla R. Costa; Fook, Marcus V. Lia; Silva, Suedina M. Lima

    2009-01-01

    The montmorillonite (the main constituent of bentonite) has been the most commonly used inorganic load in the formation of nanocomposites chitosan / layered silicate. To evaluate its effect as an agent for the reticulation of chitosan, a sodium montmorillonite, Cloisite Na + , supplied by Southern Clay Products, Texas, USA, was used. For the reticulation of chitosan dispersions of chitosan / Cloisite Na + were prepared in different proportions and the obtained films characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TG). The results indicated that the Cloisite Na + was for efficient and the reticulation of the chitosan and can be used in place of sulfuric acid, which is one of the most common reticulants for chitosan. (author)

  7. Report of mortmorilloniticas clay in the Medina swamp (Cerro Largo district)

    International Nuclear Information System (INIS)

    Gomez Rifas, C.; Heinzen, W.; Theune, C.

    1980-01-01

    This report describes the prospect ion work for the montmorillonitics clay in the region of Medina swamp in Cerro Largo district. The existence of new deposits was detected by cartography and geological study.

  8. Clay mineralogy of innershelf sediments off Cochin, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Reddy, N.P.C.; Rao, N.V.N.D.; Dora, Y.L.

    Kaolinite, montmorillonite and illite are the clay minerals occurring in decreasing order of abundance in the Holocene sediments of inner shelf and adjacent coastal environments of Cochin Region. Southern part of Vembanad Lake, estuarine part...

  9. Clay mineral distribution from Bhimunipatnam to Pudimadaka along cental eastern continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

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

    Forty eight sediment samples, collected from 50-100m depth, have been analysed for their clay mineral composition and distribution. Kaolinite with chlorite (K + C) is the predominant mineral followed by illite and montmorillonite. K + C and illite...

  10. Stability of iron-rich magnesiowüstite in Earth's lower mantle

    Science.gov (United States)

    Ohta, K.; Fujino, K.; Kuwayama, Y.; Kondo, T.; Shimizu, K.; Ohishi, Y.

    2012-12-01

    At ambient conditions, MgO periclase and FeO wüstite form a solid solution (Mg1-xFex)O, named ferropericlase (x ≤ 0.5) and magnesiowüstite (x > 0.5). (Mg1-xFex)O ferropericlase is considered to be a major component of Earth's lower mantle, and may play an important role for its structure and dynamics. Iron-rich magnesiowüstite also needs to be considered because of possible iron enrichment at the core-mantle boundary region [e.g., Nomura et al., 2011]. Recent laser-heated diamond anvil cell experiments on FeO revealed that NaCl-type (B1) structured FeO underwent an insulator-metal transition at about 70 GPa and 1800 K without any structural transformation [Fischer et al., 2011; Ohta et al., 2012]. These results imply that the metallic B1 FeO would require a two-phase field for the MgO-FeO binary system due to different chemical bonding between insulating MgO and metallic FeO. We performed simultaneous electrical conductivity and x-ray diffraction measurements on (Mg0.20Fe0.80)O and (Mg0.05Fe0.95)O magnesiowüstite up to 140 GPa and 2100 K, and then examined recovered samples by using analytical transmission electron microprobe. We obtained some evidences for the dissociation of (Mg0.05Fe0.95)O into lighter and heavier phases than starting material occurring above 70 GPa and 1900 K, which is most likely due to the metallization of FeO component. On the other hand, we did not observe such dissociation and metallization in (Mg0.20Fe0.80)O. Observed dissociation in (Mg0.05Fe0.95)O might contribute to the heterogeneity in seismic wave and electrical conductivity at the Earth's core-mantle boundary region.

  11. Rheology of ABS and binary of organo clay nanocomposites

    International Nuclear Information System (INIS)

    Galvan, Danieli; Mazzucco, Mateus; Carneiro, Fabio; Bartoli, Julio R.; Morales, Ana Rita; D'Avila, Marcos A.

    2011-01-01

    nanocomposites of poly(acrylonitrile-butadiene-styrene) and organically modified montmorillonite clays by melt intercalation on a co-rotating twin-screw extruder were prepared and characterized. It was studied the effects of screw torque and a binary mixture of organically modified montmorillonites on the intercalation/exfoliation of organoclays in the polymer matrix, characterized by X-ray diffraction morphological analyses and by capillary and parallel plates rheological analyses. (author)

  12. Cobalt 60 cation exchange with mexican clays

    International Nuclear Information System (INIS)

    Nava Galve, R.G.

    1993-01-01

    Mexican clays can be used to remove radioactive elements from contaminated aqueous solutions. Cation exchange experiments were performed with 60 Co radioactive solution. In the present work the effect of contact time on the sorption of Co 2+ was studied. The contact time in hydrated montmorillonite was from 5 to 120 minutes and in dehydrated montmorillonite 5 to 1400 minutes. The Co 2+ uptake value was, in hydrated montmorillonite, between 0.3 to 0.85 m eq/g and in dehydrated montmorillonite, between 0.6 to 1.40 m eq/g. The experiments were done in a pH 5.1 to 5.7 and normal conditions. XRD patterns were used to characterize the samples. The crystallinity was determined by X-ray Diffraction and it was maintained before and after the cation exchange. DTA thermo grams showed the temperatures of the lost humidity and crystallization water. Finally, was observed that dehydrated montmorillonite adsorb more cobalt than hydrated montmorillonite. (Author)

  13. Organic or organometallic template mediated clay synthesis

    Science.gov (United States)

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

    1994-01-01

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

  14. Litterfall dynamics in a iron-rich rock outcrop complex in the southeastern portion of the Iron Quadrangle of Brazil

    Directory of Open Access Journals (Sweden)

    Eduardo André Ribeiro Valim

    2013-06-01

    Full Text Available Ecosystems on cangas (duricrust present considerable heterogeneity of habitats due to microtopographic variations, soil accumulation and a variety of plant functional groups. Therefore, spatial and temporal ecosystem processes such as litterfall are to be expected to be large, and the absence of a level of productivity represents all the facets of iron-rich landscapes. We investigated litterfall in a iron-rich rock complex in the Iron Quadrangle of Brazil, with habitats formed on different evolutionary stages of the soil, resulting in a gradient of biomass, canopy cover and community structure. The measurements were made in open field areas, dominated by herb-shrub vegetation and interspersed with islands of dense vegetation in which there were individual trees, as well as in areas of semideciduous forest. The litterfall, especially that of leaf litter, followed the gradient of woody cover and was approximately two times greater in the forest formation. However, the spatial and temporal variations in deposition were greatest in the herb-shrub areas and least in the semideciduous forest area, intermediate values being obtained for the tree island areas. The peaks in litterfall also varied among habitats, occurring in some periods of the rainy season and during the transition from rainy to dry in the herb-shrub and tree island areas, whereas they occurred at the end of the dry season in the semideciduous forest area. The results show significant differences in the patterns of litterfall among different physiognomies within the same iron-rich rock complex, indicating the need for expanded studies, focusing on the flow of matter and energy in such environments.

  15. Organophilization and characterization of commercial bentonite clays

    International Nuclear Information System (INIS)

    Cunha, B.B. da; Lima, J.C.C.; Alves, A.M.; Araujo, E.M.; Melo, T.J.A. de

    2012-01-01

    Bentonite clay is a plastic changes resulting from volcanic ash, consisting mostly of montmorillonite. The state of Paraiba is a major source of bentonite clay from Brazil, where the main oil fields are located in Boa Vista and represents the largest national production of raw and beneficiated bentonite. Aimed at the commercial value of this type of clay and its high applicability in the polls, this article aims to make a comparison between two kinds of clay, a national (Brasgel) and other imported (Cloisite) from organophilization of two commercial bentonite, ionic surfactant with Praepagem WB, and characterize them by XRD, FTIR and TG / DTG. We observe that despite getting inferior properties, the clay presents national values very similar to those presented by imported clay. (author)

  16. Characterisation, in vitro release study, and antibacterial activity of montmorillonite-gentamicin complex material

    International Nuclear Information System (INIS)

    Rapacz-Kmita, A.; Bućko, M.M.; Stodolak-Zych, E.; Mikołajczyk, M.; Dudek, P.; nd Department of Surgery, Kopernika 21, 31-501 Krakow (Poland))" data-affiliation=" (Jagiellonian University, Medical College, 2nd Department of Surgery, Kopernika 21, 31-501 Krakow (Poland))" >Trybus, M.

    2017-01-01

    The present paper concerns the potential use of montmorillonite as a drug carrier and focusses on the intercalation of the studied clay with gentamicin (an aminoglycoside antibiotic) at various temperatures (20, 50 and 80 °C). The experiments were performed to identify the temperature required for the optimum intercalation of gentamicin into the interlayer of montmorillonite. The structural and microstructural properties of gentamicin and the potential for introducing it between smectite clay layers were investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopic techniques, and SEM with EDS analysis. Additionally, the in vitro drug release behaviour of the montmorillonite-gentamicin complex and its antibacterial activity against Escherichia coli (E. coli) bacteria was investigated. Based on these studies, the impact of temperature on the intercalation of the drug between layers of smectite was evaluated. It was found that an intercalation temperature of 50 °C resulted in the highest shift in the position of principle peak d (001) as measured by XRD, suggesting, that the greatest amount of gentamicin had been introduced into the interlayer space of montmorillonite at this temperature. Subsequently, the montmorillonite-gentamicin complex material obtained at 50 °C revealed the greatest capacity for killing E. coli bacteria during an in vitro test. - Highlights: • A novel montmorillonite-gentamicin hybrid materials was prepared as potential drug carrier. • Optimal conditions for the intercalation of gentamicin into the interlayer space of montmorillonite were tested. • The MMT-G complex material obtained at 50 °C revealed the greatest capacity for killing E. coli during the inhibitory zone test. • Modulating drug delivery was monitored and confirmed in in vitro drug release study.

  17. Characterisation, in vitro release study, and antibacterial activity of montmorillonite-gentamicin complex material

    Energy Technology Data Exchange (ETDEWEB)

    Rapacz-Kmita, A., E-mail: kmita@agh.edu.pl [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Mickiewicza 30, 30-059 Krakow (Poland); Bućko, M.M.; Stodolak-Zych, E. [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Mickiewicza 30, 30-059 Krakow (Poland); Mikołajczyk, M. [The University Hospital in Krakow, Division of Microbiology, Kopernika 19, 31-501 Krakow (Poland); Dudek, P. [AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Mickiewicza 30, 30-059 Krakow (Poland); Trybus, M. [Jagiellonian University, Medical College, 2" n" d Department of Surgery, Kopernika 21, 31-501 Krakow (Poland)

    2017-01-01

    The present paper concerns the potential use of montmorillonite as a drug carrier and focusses on the intercalation of the studied clay with gentamicin (an aminoglycoside antibiotic) at various temperatures (20, 50 and 80 °C). The experiments were performed to identify the temperature required for the optimum intercalation of gentamicin into the interlayer of montmorillonite. The structural and microstructural properties of gentamicin and the potential for introducing it between smectite clay layers were investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopic techniques, and SEM with EDS analysis. Additionally, the in vitro drug release behaviour of the montmorillonite-gentamicin complex and its antibacterial activity against Escherichia coli (E. coli) bacteria was investigated. Based on these studies, the impact of temperature on the intercalation of the drug between layers of smectite was evaluated. It was found that an intercalation temperature of 50 °C resulted in the highest shift in the position of principle peak d{sub (001)} as measured by XRD, suggesting, that the greatest amount of gentamicin had been introduced into the interlayer space of montmorillonite at this temperature. Subsequently, the montmorillonite-gentamicin complex material obtained at 50 °C revealed the greatest capacity for killing E. coli bacteria during an in vitro test. - Highlights: • A novel montmorillonite-gentamicin hybrid materials was prepared as potential drug carrier. • Optimal conditions for the intercalation of gentamicin into the interlayer space of montmorillonite were tested. • The MMT-G complex material obtained at 50 °C revealed the greatest capacity for killing E. coli during the inhibitory zone test. • Modulating drug delivery was monitored and confirmed in in vitro drug release study.

  18. Insightful understanding of the role of clay topology on the stability of biomimetic hybrid chitosan-clay thin films and CO2-dried porous aerogel microspheres

    OpenAIRE

    Frindy, Sana; Primo Arnau, Ana Maria; Qaiss, Abou el Kacem; Bouhfid, Rachid; Lahcini, Mohamed; García Gómez, Hermenegildo; Bousmina, Mosto; El Kadib, Abdelkrim

    2016-01-01

    [EN] Three natural clay-based microstructures, namely layered montmorillonite (MMT), nanotubular halloysite (HNT) and micro-fibrillar sepiolite (SP) were used for the synthesis of hybrid chitosan-clay thin films and porous aerogel microspheres. At a first glance, a decrease in the viscosity of the three gel forming solutions was noticed as a result of breaking the mutual polymeric chains interaction by the clay microstructure. Upon casting, chitosan-clay films displayed enhanced hydrophilicit...

  19. Physico-chemical impacts of cementitiously-derived calcium and silica on sodium montmorillonite

    International Nuclear Information System (INIS)

    Kinsela, Andrew S.; Tjitradjaja, Alice; Collins, Richard N.; Waite, T. David; Macdonald, Bennett C.T.; White, Ian; PAYNE, Timothy E.

    2012-01-01

    The storage of nuclear waste frequently involves the construction of a concrete encasement adjacent to an engineered clay barrier, which can expose the swelling clay to elevated concentrations of certain cations (particularly calcium) and very high alkalinity (pH 10 - 13). These conditions have the capacity to degrade the integrity of the clay layer and, as such, it is necessary to fully understand the effects of all possible biogeochemical interactions involved. In this study, the changes in hydraulic conductivities and other physico-chemical properties of Na-montmorillonite assemblages under the influence of both highly alkaline (pH 9 and 12) conditions and elevated concentrations of calcium and silica are examined. The Na-montmorillonite suspensions and filtration experimental method is presented, as well as the electrophoresis characterization technique

  20. Localization of cesium on montmorillonite surface investigated by frequency modulation atomic force microscopy

    Science.gov (United States)

    Araki, Yuki; Satoh, Hisao; Okumura, Masahiko; Onishi, Hiroshi

    2017-11-01

    Cation exchange of clay mineral is typically analyzed without microscopic study of the clay surfaces. In order to reveal the distribution of exchangeable cations at the clay surface, we performed in situ atomic-scale observations of the surface changes in Na-rich montmorillonite due to exchange with Cs cations using frequency modulation atomic force microscopy (FM-AFM). Lines of protrusion were observed on the surface in aqueous CsCl solution. The amount of Cs of the montmorillonite particles analyzed by energy dispersive X-ray spectrometry was consistent with the ratio of the number of linear protrusions to all protrusions in the FM-AFM images. The results showed that the protrusions represent adsorbed Cs cations. The images indicated that Cs cations at the surface were immobile, and their occupancy remained constant at 10% of the cation sites at the surface with different immersion times in the CsCl solution. This suggests that the mobility and the number of Cs cations at the surface are controlled by the permanent charge of montmorillonite; however, the Cs distribution at the surface is independent of the charge distribution of the inner silicate layer. Our atomic-scale observations demonstrate that surface cations are distributed in different ways in montmorillonite and mica.

  1. Four-branched compounds coupled Si and iron-rich intermetallics in near eutectic Al-Si alloys

    International Nuclear Information System (INIS)

    Wu, Yuying; Liu, Xiangfa; Jiang, Binggang; Bian, Xiufang

    2007-01-01

    Many four-branched compounds coupled Si and iron-rich intermetallics were observed in near eutectic Al-Si alloy modified with Al-P master alloy. Such four-branched compounds have never been reported before, but in our case it seems to be commonly observed. In this work the growth characterization of the four-branched compounds are scrutinized with a JXA-8800 electron microprobe (EPMA). More deep study of the formation of four-branched compounds is performed by SEM and TEM analysis. The characterization of the four-branched compounds is that of a primary silicon in the center with four iron-rich intermetallics around. Experimental results also show that the precipitation of primary silicon is the key factor for the formation of four-branched compounds. And WHS-theory explains the growth mechanism of the four-branched compounds. In detail, subsequent twinning within the primary silicon provides four-fold coordination sites on the surface, and then the α-Al(Fe,Mn)-Si phase nucleates on the surface of the primary silicon

  2. Controlled release of agrochemicals intercalated into montmorillonite interlayer space.

    Science.gov (United States)

    Wanyika, Harrison

    2014-01-01

    Periodic application of agrochemicals has led to high cost of production and serious environmental pollution. In this study, the ability of montmorillonite (MMT) clay to act as a controlled release carrier for model agrochemical molecules has been investigated. Urea was loaded into MMT by a simple immersion technique while loading of metalaxyl was achieved by a rotary evaporation method. The successful incorporation of the agrochemicals into the interlayer space of MMT was confirmed by several techniques, such as, significant expansion of the interlayer space, reduction of Barrett-Joyner-Halenda (BJH) pore volumes and Brunauer-Emmett-Teller (BET) surface areas, and appearance of urea and metalaxyl characteristic bands on the Fourier-transform infrared spectra of the urea loaded montmorillonite (UMMT) and metalaxyl loaded montmorillonite (RMMT) complexes. Controlled release of the trapped molecules from the matrix was done in water and in the soil. The results reveal slow and sustained release behaviour for UMMT for a period of 10 days in soil. For a period of 30 days, MMT delayed the release of metalaxyl in soil by more than 6 times. It is evident that MMT could be used to improve the efficiency of urea and metalaxyl delivery in the soil.

  3. Ability of Cu2+-montmorillonite to accept an toxic pollutants

    International Nuclear Information System (INIS)

    Janikova, V.; Jona, E.; Janik, R.; Pavlik, V.

    2015-01-01

    It is global problem that toxic pollutants are in the permanent contact to people through soil and water. Nowadays, it is important to eliminate these pollutants for future generations and to keep environment in the health condition. In relation to this article, aromatic organic compounds like benzene, phenol and aniline were chosen. These are used in various branches of industry, mainly in rubber industry or for production of dyes and in addition, phenol is commonly used in cosmetics or in food industry. Montmorillonite is clay mineral consisting of 2:1 sheets (tetrahedral:octahedral) and interlayer space where exchangeable cations and water molecules are present. Due to its structure, montmorillonite is able to accept some compounds or pollutants. This is the reason why it is mainly used as the covering material of radioactive waste in order to remove toxic pollutants. For investigation of toxic pollutants removing, XRD powder diffraction, infrared spectroscopy and thermal analysis were used. Our results show that Cu 2+ -montmorillonite is able to accept toxic benzene ring-based pollutants into interlayer. This mentioned ability can be proven on the basis of the investigation results relating to difference of interlayer distance, typical frequencies of -OH group or -NH 2 group, while these results were supplemented by thermal properties. (authors)

  4. 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…

  5. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2001-01-01

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

  6. Morphological, dielectric and electric conductivity characteristics of clay-containing nanohybrids of Poly(N-Vinyl Carbazole) and Polypyrrole

    CSIR Research Space (South Africa)

    Haldar, I

    2012-10-01

    Full Text Available Poly(N-vinyl carbazole) (PNVC) and polypyrrole (PPY)-montmorillonite (MMT) clay hybrids were prepared by mechanical grinding of the respective monomers with MMT followed by subsequent standard processing methods. Fourier transform infrared...

  7. Molecular simulation of the role of interlayer water on the mechanical properties of montmorillonite

    International Nuclear Information System (INIS)

    Carrier, Benoit; Vandamme, Matthieu; Ebrahimi, Davoud; Whittle, Andrew J.; Pellenq, Roland J.M.; Van Damme, Henri

    2012-01-01

    Document available in extended abstract form only. Full text of publication follows: Montmorillonite - a swelling clay - is the main component of the clay fraction of the Callovo-Oxfordian argillite, which is considered as a possible host rock for radioactive waste disposal, and of the sealing bentonite plugs of storage tunnels. Montmorillonite layers have a great ability to adsorb water, resulting in the swelling of the clay. Montmorillonite consists of water molecules and sodium or calcium cations between negatively charged layers. Both the water content of the interlayer space and the nature of the charge-balancing cations are expected to have an effect on the mechanical properties of the clay layer. Computer simulations allow to reproduce the experimental swelling isotherms of the layers and to gain a deeper understanding of the physical mechanisms of the swelling process. They show how water is organized in discrete layers and how this process depends on the type of inter-layer cation. However, the effect of the swelling on the mechanical properties of the nano-scale have not been fully investigated. The objective of this work is to compute the elastic properties of a Na + - Montmorillonite and a Ca 2+ -Montmorillonite versus relative humidity at 300 K. The results of this work is the first step to build a macroscopic state equation of unsaturated clay-based materials. We use a simulation cell containing two Montmorillonite layers and sodium or calcium counterions. The partial charges of the atoms and the interatomic interaction parameters are given by the CLAYFF force field. Grand Canonical Monte-Carlo simulations are used to compute the adsorption/desorption isotherm. Each equilibrium configuration is then strained in all directions of space. Then, we perform Molecular Dynamics and compute the stress tensor and all the components of the elasticity tensor. We present the evolution of the elastic properties of the clay layers with the relative humidity. In

  8. Functional properties of extruded nano composites based on cassava starch, polyvinyl alcohol and montmorillonite

    International Nuclear Information System (INIS)

    Debiagi, Flavia; Mali, Suzana

    2011-01-01

    The objectives of this work were to produce expanded nano composites (foams) based on starch, PVA and sodium montmorillonite and characterize them according to their expansion index (EI), density, water absorption capacity (WSC), mechanical properties and X-ray diffraction. The nano composites were prepared in a single-screw extruder using different starch contents (97.6 - 55.2 g/100 g formulation), PVA (0 - 40 g/100 g formulation), unmodified nano clay - Closite - Na (0 - 4. 8 g/100 g formulation) and glycerol (20 g/100 g formulation) as plasticizer. The addition of montmorillonite and PVA resulted in an increase of EI and a decrease of density of the samples, and reduced WSC and increased the mechanical strength of the foams. Through the analysis of X-ray diffraction can be observed that the addition of montmorillonite led to production of intercalated nano composites in all samples. (author)

  9. Hydration Phase Diagram of Clay Particles from Molecular Simulations.

    Science.gov (United States)

    Honorio, Tulio; Brochard, Laurent; Vandamme, Matthieu

    2017-11-07

    Adsorption plays a fundamental role in the behavior of clays. Because of the confinement between solid clay layers on the nanoscale, adsorbed water is structured in layers, which can occupy a specific volume. The transition between these states is intimately related to key features of clay thermo-hydro-mechanical behavior. In this article, we consider the hydration states of clays as phases and the transition between these states as phase changes. The thermodynamic formulation supporting this idea is presented. Then, the results from grand canonical Monte Carlo simulations of sodium montmorillonite are used to derive hydration phase diagrams. The stability analysis presented here explains the coexistence of different hydration states at clay particle scale and improves our understanding of the irreversibilities of clay thermo-hydro-mechanical behavior. Our results provide insights into the mechanics of the elementary constituents of clays, which is crucial for a better understanding of the macroscopic behavior of clay-rich rocks and soils.

  10. Acidity of edge surface sites of montmorillonite and kaolinite

    Science.gov (United States)

    Liu, Xiandong; Lu, Xiancai; Sprik, Michiel; Cheng, Jun; Meijer, Evert Jan; Wang, Rucheng

    2013-09-01

    Acid-base chemistry of clay minerals is central to their interfacial properties, but up to now a quantitative understanding on the surface acidity is still lacking. In this study, with first principles molecular dynamics (FPMD) based vertical energy gap technique, we calculate the acidity constants of surface groups on (0 1 0)-type edges of montmorillonite and kaolinite, which are representatives of 2:1 and 1:1-type clay minerals, respectively. It shows that tbnd Si-OH and tbnd Al-OH2OH groups of kaolinite have pKas of 6.9 and 5.7 and those of montmorillonite have pKas of 7.0 and 8.3, respectively. For each mineral, the calculated pKas are consistent with the experimental ranges derived from fittings of titration curves, indicating that tbnd Si-OH and tbnd Al-OH2OH groups are the major acidic sites responsible to pH-dependent experimental observations. The effect of Mg substitution in montmorillonite is investigated and it is found that Mg substitution increases the pKas of the neighboring tbnd Si-OH and tbnd Si-OH2 groups by 2-3 pKa units. Furthermore, our calculation shows that the pKa of edge tbnd Mg-(OH2)2 is as high as 13.2, indicating the protonated state dominates under common pH. Together with previous adsorption experiments, our derived acidity constants suggest that tbnd Si-O- and tbnd Al-(OH)2 groups are the most probable edge sites for complexing heavy metal cations.

  11. QINS studies of water diffusion in Na-Montmorillonite

    International Nuclear Information System (INIS)

    Gay-Duchosal, M.

    1999-01-01

    Complete text of publication follows. The rotational and translational motion of interlayer water was investigated in Na-Montmorillonite as a function of the humidity (one-, two- and three-layers). Partially orientated samples produced by deposition onto a filter under pressure were used. Measurements were made at two different resolutions 120 μeV and 36 μeV. In order to observe the anisotropy, measurements with sample orientations of 135 and 45 degree were made with respect to the incident beam corresponding to Q-parallel and Q-perpendicular to the clay layers. The fitting procedure consists of an elastic term based on a fit to an analogous D 2 O hydrated sample and a quasielastic term containing both rotational and translational contributions (1). At low resolution with Q-parallel a rotational broadening was observed that increases, indicating increasing water mobility, as the water content and hence the layer spacing increases. For the three-layer hydrate with the two different orientations the broadening is the same showing no measurable anisotropy of the rotational motion. At high resolution an additional broadening was seen due to translational diffusion of a similar magnitude to that measured previously for Li-Montmorillonite (2). We are currently refining our data analysis in order to determine whether the anisotropy of the translational motion with respect to the orientation of the clay is measurable. (author)

  12. Biodegradation of bacterial polysaccharides adsorbed on montmorillonite

    International Nuclear Information System (INIS)

    Guckert, A.; Tok, H.H.; Jacquin, F.

    1977-01-01

    In this research, by means of a model, a study was made of the biodegradation of microbial organic compounds adsorbed on clays, with a parallel experiment on Fontainebleau sand serving as the control. During incubation the three classes of organic matter ( 14 C-labelled glucose, 14 C-labelled polysaccharides and 14 C-labelled microbial cells) mineralize more actively in the presence of sand than in the presence of clay, since the latter provides protection against biodegradation. Mineralization of the adsorbed organic compounds, however, is marked by clear-cut differences after three weeks - glucose (55%)>polysaccharides (43%)>microbial organisms (7.3%). After incubation, chemical extraction of the organo-mineral complexes by alkaline solvents shows only water-soluble and alkali-soluble products in the case of sand; conversely, in that of montmorillonite the bulk of the 14 C was found in the non-extractable fraction or humin (18.1% of the initial 14 C for glucose, 27.3% for the polysaccharides, and 67.6% for the microbial organisms). A second incubation carried out after a phase in which there was drying and remoistening of the organo-mineral complexes, brings to light the important part played by climatic alternations during the biodegradation process. A new mineralization phase is observed, affecting more the bacterial organisms (14.1%) than the polysaccharides (6.3%), with the glucose-base complexes occupying an intermediate position (11.2%). The chemical fractioning of the organo-mineral complexes following re-incubation shows the stability of 14 C in humin very clearly, especially in the case of polysaccharides, where the mineralization phase relates primarily to the products extractable with alkalis. (author)

  13. Macrostructure of smectite-water systems. Influence of anionic poly-electrolytes on the organisation of montmorillonite suspensions

    International Nuclear Information System (INIS)

    Morvan, Mikel

    1993-01-01

    In its first part, this research thesis reports a bibliographical study which aimed at highlighting the main aspects of smectite swelling, discusses the organisation of smectite suspension, and briefly presents the knowledge on clay-polymer mixtures. Then, the author describes the method he used to characterise clay suspensions (relaxation, MNR, osmometric techniques, small-angle X-ray diffraction), and theoretical elements required to interpret results. He addresses more particularly the organisation of smectite-water systems with either a natural smectite (montmorillonite) or a synthetic one (laponite) which have different geometries. The last part addresses the interactions between a montmorillonite suspension and sodium polyacrylates. The author, based on the use of small-angle X-ray diffraction and the measurement of the polyelectrolyte osmotic pressure, proposes a new interpretation of the action mechanism of an anionic polyelectrolyte of low molecular mass within a montmorillonite suspension

  14. Structure and mechanical properties of polyamide 6/Brazilian clay nanocomposites

    Directory of Open Access Journals (Sweden)

    Amanda Melissa Damião Leite

    2009-06-01

    Full Text Available Recent interest in polymer/organoclays nanocomposites systems is motivated by the possibility of achieving enhanced properties and added functionality at lower clay loading as compared to conventional micron size fillers. By adding montmorillonite clay to polyamide 6 increases the Young modulus, yield strength and also improves barrier properties. In this work, nanocomposites of polyamide 6 with montmorillonite clay were obtained. The clay was chemically modified with three different quaternary ammonium salts such as: Dodigen, Genamin and Cetremide. In this case, a dispersion of Na-MMT was stirred and a salt equivalent to 1:1 of cation exchange capacity (CEC of Na-MMT was added to the dispersion. The montmorillonite clay (untreated and treated by ammonium salts and nanocomposites were characterized by X ray diffractions. Also the nanocomposites were characterized by transmission electron microscopy and mechanical properties. The results indicated that all the quaternary ammonium salts were intercalated between the layers of clay, leading to an expansion of the interlayer spacing. The obtained nanocomposites showed better mechanical properties when compared to polyamide 6. The clay acted as reinforcing filler, increasing the rigidity of nanocomposites and decreasing its ductility.

  15. Removal of remazol yellow with modified clays with iron

    International Nuclear Information System (INIS)

    Diaz-Gomez T, A. P.

    2012-01-01

    Clays have the ability to absorb water and to retain in its structure both hydrophilic and hydrophobic substances, therefore, it is possible to use them in the sorption of dyes from waste water, in order to avoid affecting water bodies or storm drains when they are discharged. In this paper the montmorillonite KSF and a sodium bentonite from the Morelos State, Mexico were studied for the sorption of an azo dye used in textiles knows as remazol yellow. These clays were modified with iron, the dye sorption behaviors and their regeneration processes for their reuse were determined. It was difficult to separate the sodium bentonite after being in contact with aqueous solutions; therefore it was nor a candidate dor the removal of remazol yellow from aqueous solutions. The montmorillonite KSF was characterized before and after the iron modification, and after its regeneration by scanning electron microscopy (elemental analysis), infrared spectrometry, X-ray diffraction, and the specific areas of the materials were determined by Bet analysis. The adsorption equilibrium time and the adsorption rate for remazol yellow were determined from the fitting of the experimental results to mathematical models for the unmodified and iron modified montmorillonite KSF. The adsorption capacity was determined from the adsorption isotherms and mathematical models. The influence of the ph in the sorption processes was determined as well, and it was found that, ph values between 2 and 12 do not have any influence on the adsorption processes for iron modified montmorillonite KSF. The montmorillonite KSF and the iron modified montmorillonite KSF are adequate adsorbents for the removal of remazol yellow from aqueous solutions. Although, the sorption capacity for the unmodified montmorillonite KSF is higher (about 10%) than the capacity for the iron modified montmorillonite KSF and the stability of the last one increased. The saturated clays with remazol yellow were treated with Fenton reactive

  16. Crude oil polycyclic aromatic hydrocarbons removal via clay-microbe-oil interactions: Effect of acid activated clay minerals.

    Science.gov (United States)

    Ugochukwu, Uzochukwu C; Fialips, Claire I

    2017-07-01

    Acid treatment of clay minerals is known to modify their properties such as increase their surface area and surface acidity, making them suitable as catalysts in many chemical processes. However, the role of these surface properties during biodegradation processes of polycyclic aromatic hydrocarbons (PAHs) is only known for mild acid (0.5 M Hydrochloric acid) treated clays. Four different clay minerals were used for this study: a montmorillonite, a saponite, a palygorskite and a kaolinite. They were treated with 3 M hydrochloric acid to produce acid activated clay minerals. The role of the acid activated montmorillonite, saponite, palygorskite and kaolinite in comparison with the unmodified clay minerals in the removal of PAHs during biodegradation was investigated in microcosm experiments. The microcosm experiments contained micro-organisms, oil, and clays in aqueous medium with a hydrocarbon degrading microorganism community predominantly composed of Alcanivorax spp. Obtained results indicated that acid activated clays and unmodified kaolinite did not enhance the biodegradation of the PAHs whereas unmodified montmorillonite, palygorskite and saponite enhanced their biodegradation. In addition, unmodified palygorskite adsorbed the PAHs significantly due to its unique channel structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Effects of Graded Levels of Montmorillonite on Performance, Hematological Parameters and Bone Mineralization in Weaned Pigs

    Directory of Open Access Journals (Sweden)

    Q. W. Duan

    2013-11-01

    Full Text Available The aim of this study was to investigate the effects of graded levels of montmorillonite, a constituent of clay, on performance, hematological parameters and bone mineralization in weaned pigs. One hundred and twenty, 35-d-old crossbred pigs (Duroc×Large White×Landrace, 10.50±1.20 kg were used in a 28-d experiment and fed either an unsupplemented corn-soybean meal basal diet or similar diets supplemented with 0.5, 1.0, 2.5 or 5.0% montmorillonite added at the expense of wheat bran. Each treatment was replicated six times with four pigs (two barrows and two gilts per replicate. Feed intake declined (linear and quadratic effect, p< 0.01 with increasing level of montmorillonite while feed conversion was improved (linear and quadratic effect, p<0.01. Daily gain was unaffected by dietary treatment. Plasma myeloperoxidase declined linearly (p = 0.03 with increasing dietary level of montmorillonite. Plasma malondialdehyde and nitric oxide levels were quadratically affected (p<0.01 by montmorillonite with increases observed for pigs fed the 0.5 and 1.0% levels which then declined for pigs fed the 2.5 and 5.0% treatments. In bone, the content of potassium, sodium, copper, iron, manganese and magnesium were decreased (linear and quadratic effect, p<0.01 in response to an increase of dietary montmorillonite. These results suggest that dietary inclusion of montmorillonite at levels as high as 5.0% does not result in overt toxicity but could induce potential oxidative damage and reduce bone mineralization in pigs.

  18. XRD, TEM, and thermal analysis of Arizona Ca-montmorillonites modified with didodecyldimethylammonium bromide.

    Science.gov (United States)

    Sun, Zhiming; Park, Yuri; Zheng, Shuilin; Ayoko, Godwin A; Frost, Ray L

    2013-10-15

    An Arizona SAz-2 calcium montmorillonite was modified by a typical dialkyl cationic surfactant (didodecyldimethylammonium bromide, abbreviated to DDDMA) through direct ion exchange. The obtained organoclays were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), high-resolution thermogravimetric analysis (HR-TG), and infrared emission spectroscopy (IES). The intercalation of surfactants greatly increased the basal spacing of the interlayers and the conformation arrangement of the loaded surfactant were assessed based on the XRD and TEM measurements. This work shows that the dialkyl surfactant can be directly intercalated into the montmorillonite without first undergoing Na(+) exchange. Moreover, the thermal stability of organoclays and the different arrangements of the surfactant molecules intercalated in the SAz-2 Ca-montmorillonite were determined by a combination of TG and IES techniques. The detailed conformational ordering of different intercalated surfactants under different conditions was also studied. The surfactant molecule DDDMA has proved to be thermally stable even at 400°C which indicates that the prepared organoclay is stable to significantly high temperatures. This study offers new insights into the structure and thermal stabilities of SAz-2 Ca-montmorillonite modified with DDDMA. The experimental results also confirm the potential applications of organic SAz-2 Ca-montmorillonites as adsorbents and polymer-clay nanocomposites. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. The hydroisomerization activity of nickel-substituted mica montmorillonite clay

    NARCIS (Netherlands)

    Santen, van R.A.; Röbschläger, K.H.W.; Emeis, C.A.; Grasselli, R.K.; Brazdil, J.F.

    1985-01-01

    Three-layer sheet aluminosilicates, when exchanged into the acidic form, are far less active as hydroisomerization catalysts than zeolites having a comparable surface proton density. However, introducing Ni2+ or Co2+ into the octahedral positions of the Al3+ layer in synthetic beidellite results in

  20. Thermal characterization of montmorillonite clays saturated with various cations

    Czech Academy of Sciences Publication Activity Database

    Balek, V.; Beneš, M.; Šubrt, Jan; Pérez, R.

    2008-01-01

    Roč. 92, č. 1 (2008), s. 191-197 ISSN 1388-6150 R&D Projects: GA MŠk LC523 Institutional research plan: CEZ:AV0Z40320502 Keywords : collapse of interlayer space * dehydration * emanation thermal analysis Subject RIV: CA - Inorganic Chemistry Impact factor: 1.630, year: 2008

  1. Moessbauer spectroscopy of iron in clay minerals

    International Nuclear Information System (INIS)

    Raclavsky, K.; Sitek, J.; Lipka, J.

    1975-01-01

    Selected pure clay minerals predominantly of Czechoslovak origin were studied, such as montmorillonite, nontronite, beidellite, glauconite, seladonite, illite, vermiculite, saponite, palygorskite, goethite. Moessbauer measurements were performed at room temperature with a 57 Co in Pd source. The spectra were fitted by the least square method. The parameters of the measured Moessbauer spectra are given. The values of isomer shifts, quadrupole splittings and line widths were obtained with an error of +- 0.03 mm/sec. (Z.S.)

  2. Montmorillonite polyaniline nanocomposites: Preparation, characterization and investigation of mechanical properties

    International Nuclear Information System (INIS)

    Soundararajah, Q.Y.; Karunaratne, B.S.B.; Rajapakse, R.M.G.

    2009-01-01

    The interest in clay polymer nanocomposites (CPN) materials, initially developed by researchers at Toyota, has grown dramatically over the last decade. They have attracted great interest, both in industry and in academia, because they often exhibit remarkable improvement in materials' properties when compared with virgin polymer or conventional micro- and macro-composites. These improvements can include high moduli, increased strength and heat resistance, decreased gas permeability and flammability, optical transparency and increased biodegradability of biodegradable polymers. Such enhancement in the properties of nanocomposites occurs mostly due to their unique phase morphology and improved interfacial properties. Because of these enhanced properties they find applications in the fields of electronics, automobile industry, packaging, and construction. This study aims at investigating the mechanical property enhancement of polyaniline (PANI) intercalated with montmorillonite (MMT) clay. The MMT-PANI nanocomposites displayed improved mechanical properties compared to the neat polymer or clay. The enhancement was achieved at low clay content probably due to its exfoliated structure. The increased interfacial areas and improved bond characteristics may attribute to the mechanical property enhancement

  3. Mineralogy of the Tertiary Clay Deposits in Makkah and Rabigh Quadrangles, West Central Arabian Shield, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    M.H. Basyoni

    2002-06-01

    Full Text Available The mineralogy of the Tertiary clay deposits in Makkah and Rabigh quadrangles was thoroughly investigated by X-ray diffraction and differential thermal and thermogravimetric analyses in addition to other techniques. Results show that the investigated samples are predominantly composed of montmorillonite (Ca++ and/or Mg++ rich variety and kaolinite, associated with subordinate illite and minor chlorite. Mixed layer montmorillonite-illite is recorded only in two samples. The relative abundance of these minerals by X-ray diffraction analysis showed that the studied clay deposits are of three types. The first, which is the most common, is highly montmorillonitic, the second is made up of a mixture of montmorillonite followed by kaolinite and illite and the third is highly kaolinitic with some montmorillonite. Generally, kaolinite shows a southward increase in Makkah quadrangle while chlorite, as a minor component, shows a northward increase in Rabigh quadrangle.

  4. 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.

  5. Fixation of Selenium by Clay Minerals and Iron Oxides

    DEFF Research Database (Denmark)

    Hamdy, A. A.; Nielsen, Gunnar Gissel

    1977-01-01

    In studying Se fixation, soil components capable of retaining Se were investigated. The importance of Fe hydrous oxides in the fixation of Se was established. The clay minerals common to soils, such as kaolinite, montmorillonite and vermiculite, all exhibited Se fixation, but greater fixation occ...

  6. Structure of montmorillonite cointercalated with stearic acid and octadecylamine: Modeling, diffraction, IR spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Čapková, P.; Pospíšil, M.; Valášková, M.; Měřínská, D.; Trchová, Miroslava; Sedláková, Zdeňka; Weiss, Z.; Šimoník, J.

    2006-01-01

    Roč. 300, č. 1 (2006), s. 264-269 ISSN 0021-9797 R&D Projects: GA ČR GA205/05/2548; GA ČR GP205/03/D111 Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer-clay nanocomposite * intercalation * montmorillonite Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.233, year: 2006

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

    Science.gov (United States)

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

    2014-01-15

    Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific. © 2013.

  8. Adsorption of hydrogen gas and redox processes in clays.

    Science.gov (United States)

    Didier, Mathilde; Leone, Laura; Greneche, Jean-Marc; Giffaut, Eric; Charlet, Laurent

    2012-03-20

    In order to assess the adsorption properties of hydrogen gas and reactivity of adsorbed hydrogen, we measured H(2)(g) adsorption on Na synthetic montmorillonite-type clays and Callovo-Oxfordian (COx) clayrock using gas chromatography. Synthetic montmorillonites with increasing structural Fe(III) substitution (0 wt %, 3.2 wt %, and 6.4 wt % Fe) were used. Fe in the synthetic montmorillonites is principally present as structural Fe(III) ions. We studied the concomitant reduction of structural Fe(III) in the clays using (57)Fe Mössbauer spectrometry. The COx, which mainly contains smectite/illite and calcite minerals, is also studied together with the pure clay fraction of this clayrock. Experiments were performed with dry clay samples which were reacted with hydrogen gas at 90 and 120 °C for 30 to 45 days at a hydrogen partial pressure close to 0.45 bar. Results indicate that up to 0.11 wt % of hydrogen is adsorbed on the clays at 90 °C under 0.45 bar of relative pressure. (57)Fe Mössbauer spectrometry shows that up to 6% of the total structural Fe(III) initially present in these synthetic clays is reduced upon adsorption of hydrogen gas. No reduction is observed with the COx sample in the present experimental conditions.

  9. 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.

  10. Water-clay interactions. Experimental study

    International Nuclear Information System (INIS)

    Gaucher, Eric

    1998-01-01

    Clay minerals contribute to the chemical composition of soil and sediment groundwaters via surface and dissolution/precipitation reactions. The understanding of those processes is still today fragmentary. In this context, our experimental purpose is to identify the contribution of each reaction in the chemical composition of water in a water/clay System. Kaolinite, illite, montmorillonite are the reference clays. After a fine mineralogical study, the exchange equilibria between K + and H + are characterised. Different exchange sites are identified and the exchange capacities and selectivity coefficients are quantified. Then, mixtures of the three clays are equilibrated with acidic and basic (I≤10 -2 M) solutions at 25 deg. C, 60 deg. C, 80 deg. C, during 320 days. The System evolution is observed by chemical analysis of the solutions and mineralogical analysis by TEM. We show that montmorillonite is unstable compared to the kaolinite/amorphous silica assemblage for solutions of pH<7. Aqueous silica is probably controlled by the kinetics of dissolution of the montmorillonite in moderate pH media. In more acidic solutions, amorphous silica precipitates. Al is under control of 'kaolinite' neo-formations. The use of the selectivity coefficients in a numerical simulation shows that K + concentration depends on exchange reactions. The pH has a more complicated evolution, which is not completely understood. This evolution depends on both exchange equilibria and organic acid occurrence. In this type of experiments, we have demonstrated that the equilibrium equations between smectite and kaolinite are inexact. The problem of the thermodynamic nature of clays remains and is not resolved by these solubility experiments. (author) [fr

  11. Preparation of nanocomposites based on poly(Butylene Succinate) and montmorillonite organoclay via in situ polymerization

    International Nuclear Information System (INIS)

    Ferreira, Leticia P.; Moreira, Andrei N.; Souza Junior, Fernando G. de; Pinto, Jose Carlos Costa da Silva

    2014-01-01

    Nanocomposites based on poly(butylene succinate) (PBS) and organophilic montmorillonite were synthesized via in situ polymerization using three different clay compositions (4, 6 and 8 wt%). The products were characterized by several different techniques. X-ray diffraction was useful to confirm the increase of the interlayer spacing of the clay due to the presence of the polymer chains among layers. Thermal analysis indicated that the polymerization method chosen led to materials with lower thermal stability compared to the pure PBS, due to the difficulty of chain growth in the presence of the clay. Low-field NMR technique was used to assess clay dispersion in the polymer, with exfoliated structures predominating in the nanocomposites. (author)

  12. Modified montmorillonite as vector for gene delivery.

    Science.gov (United States)

    Lin, Feng-Huei; Chen, Chia-Hao; Cheng, Winston T K; Kuo, Tzang-Fu

    2006-06-01

    Currently, gene delivery systems can be divided into two parts: viral or non-viral vectors. In general, viral vectors have a higher efficiency on gene delivery. However, they may sometimes provoke mutagenesis and carcinogenesis once re-activating in human body. Lots of non-viral vectors have been developed that tried to solve the problems happened on viral vectors. Unfortunately, most of non-viral vectors showed relatively lower transfection rate. The aim of this study is to develop a non-viral vector for gene delivery system. Montmorillonite (MMT) is one of clay minerals that consist of hydrated aluminum with Si-O tetrahedrons on the bottom of the layer and Al-O(OH)2 octahedrons on the top. The inter-layer space is about 12 A. The room is not enough to accommodate DNA for gene delivery. In the study, the cationic hexadecyltrimethylammonium (HDTMA) will be intercalated into the interlayer of MMT as a layer expander to expand the layer space for DNA accommodation. The optimal condition for the preparation of DNA-HDTMA-MMT is as follows: 1 mg of 1.5CEC HDTMA-MMT was prepared under pH value of 10.7 and with soaking time for 2 h. The DNA molecules can be protected from nuclease degradation, which can be proven by the electrophoresis analysis. DNA was successfully transfected into the nucleus of human dermal fibroblast and expressed enhanced green fluorescent protein (EGFP) gene with green fluorescence emission. The HDTMA-MMT has a great potential as a vector for gene delivery in the future.

  13. Radiation-induced catalysis of fatty acids adsorbed onto clay minerals

    International Nuclear Information System (INIS)

    Negron-Mendoza, A.; Ramos-Bernal, S.; Colin-Garcia, M.; Mosqueira, F.G.

    2015-01-01

    We studied the behavior of small fatty (acetic acid) and dicarboxylic acids (succinic and malonic acids) adsorbed onto Na + -montmorillonite (a clay mineral) and exposed to gamma radiation. A decarboxylation reaction was found to predominate when the clay was present. This preferential synthesis promoted the formation of a compound with one less carbon atom than its target compound. In the system without clay, dimerization was the predominate outcome following radiolysis. (author)

  14. Matrix effects for calcium and potassium K-X-rays, in fenugreek plants grown in iron rich soils

    International Nuclear Information System (INIS)

    Deep, Kanan; Rao, Preeti; Bansal, Himani; Mittal, Raj

    2014-01-01

    The present work comprises the matrix effects study of the plant system (plant and soil) for macronutrients Ca and K with elevated levels of iron in the soil. The earlier derived matrix effect terms from fundamental relations of intensities of analyte and substrate elements with basic atomic and experimental setup parameters had led to iterative determination of enhanced elements rather than avoiding their enhancement. The relations also facilitated the evaluations of absorption for close Z interfering constituents (like Ca and K) in samples of a lot of particular category with interpolation of matrix terms with elemental amounts. The process has already been employed successfully for potato, radish, rice and maize plants. On similar lines, the observed prominent change in interpolation parameters for the plants in the present experiment serves as a tool to check the toxicity/contamination of the growing medium. - Highlights: • Matrix effects for Ca and K in Fenugreek plant and its soil with elevated iron level. • Fenugreek plants grown in iron rich soil and treated with K/Ca fertilizers. • The matrix terms correlated to analyte and enhancer element amounts. • Interpolation of matrix terms with elemental amounts points to Fe toxicity of soil

  15. In situ characterization of organo-modified and unmodified montmorillonite aqueous suspensions by UV-visible spectroscopy.

    Science.gov (United States)

    Alin, Jonas; Rubino, Maria; Auras, Rafael

    2015-10-15

    UV-visible (UV-Vis) spectroscopy (Tyndall spectra) was applied and tested for its ability to measure organo-modified and unmodified montmorillonite (MMT) clays in aqueous suspensions. A full factorial design of experiments was used to study the influence of pH, NaCl and clay concentrations on the average particle size of the clay agglomerates. The methodology was evaluated by observing results that were consistent with previous research about the unmodified clay's behavior in aqueous suspensions. The results from this evaluation corresponded to accepted theories about the unmodified clay's behavior, indicating that the methodology is precise enough to distinguish the effects of the studied factors on these clay suspensions. The effect of clay concentration was related to the amount of ions per clay particle for the unmodified clay, but was not significant for the organo-modified MMT. The average particle size of the organo-modified MMT in suspension was significantly larger than that of the unmodified clay. Size of the organo-modified MMT agglomerates in suspension decreased in the presence of NaCl and at both high and low pH; this behavior was opposite to that of the unmodified clay. These results demonstrate that the UV-Vis methodology is well-suited for characterizing clay particle size in aqueous suspensions. The technique also is simple, rapid, and low-cost. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Survival of microorganisms in smectite clays: Implications for Martian exobiology

    Science.gov (United States)

    Moll, Deborah M.; Vestal, J. Robie

    1992-08-01

    Manned exploration of Mars may result in the contamination of that planet with terrestrial microbes, a situation requiring assessment of the survival potential of possible contaminating organisms. In this study, the survival of Bacillus subtilis, Azotobacter chroococcum, and the enteric bacteriophage MS2 was examined in clays representing terrestrial (Wyoming type montmorillonite) or Martian (Fe 3+-montmorillonite) soils exposed to terrestrial and Martian environmental conditions of temperature and atmospheric pressure and composition, but not to UV flux or oxidizing conditions. Survival of bacteria was determined by standard plate counts and biochemical and physiological measurements over 112 days. Extractable lipid phosphate was used to measure microbial biomass, and the rate of 14C-acetate incorporation into microbial lipids was used to determine physiological activity. MS2 survival was assayed by plaque counts. Both bacterial types survived terrestrial or Martian conditions in Wyoming montmorillonite better than Martian conditions in Fe 3+-montmorillonite. Decreased survival may have been caused by the lower pH of the Fe 3+-montmorillonite compared to Wyoming montmorillonite. MS2 survived simulated Mars conditions better than the terrestrial environment, likely due to stabilization of the virus caused by the cold and dry conditions of the simulated Martian environment. The survival of MS2 in the simulated Martian environment is the first published indication that viruses may be able to survive in Martian type soils. This work may have implications for planetary protection for future Mars missions.

  17. Synthesis of Collagen-Based Hydrogel Nanocomposites Using Montmorillonite and Study of Adsorption Behavior of Cd from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Gholam Bagheri Marandi

    2013-04-01

    Full Text Available Novel collagen-based hydrogel nanocomposites were synthesized by graft copolymerization of acrylamide and maleic anhydrid in the presence of different amounts of montmorillonite, using methylenebisacrylamide (MBAand ammonium persulfate (APS as crosslinker and initiator, respectively. The optimum amount of clay on the swelling properties of the samples was studied. It was found that the hydrogel nanocomposites exhibited improved swelling capacity compared with the clay-free hydrogel. Gel content was also studied and the resultsindicated that the inclusion of montmorillonite causes an increase in gel content. The sorption behavior of heavy metal ion from aqueous solutions was investigated by its relationship with pH, contact time, initial concentration of metal ion and also, montmorillonite content of the nanocomposites. The experimental data showed thatCd2+ ion adsorption increases with increasing initial concentration of Cd2+ ion in solution and the clay content. Also, the results indicated that more than 88% of the maximum adsorption capacities toward Cd2+ ion were achieved within the initial 10 minute. Functional groups of the prepared hydrogels have shown complexation abilitywith metal ions and improving hydrogels' adsorption properties. It was concluded that the nanocomposites could be used as fast-responsive, and high capacity sorbent materials in Cd2+ ion removing processes. The prepared hydrogel nanocomposites were characerized by means of XRD patterns, TGA thermal methods and FTIRspectroscopy. The XRD patterns of nanocomposites showed that the interlayer distance of montmorillonite was changed and the clay sheets were exfoliated. Furthermore, the results showed that by increasing the montmorillonite content, thermal stability of the nanocomposites was clearly improved.

  18. Samarium ion exchanged montmorillonite for high temperature cumene cracking reaction

    International Nuclear Information System (INIS)

    Binitha, N.N.

    2009-01-01

    Full text: Nano material Montmorillonite clay is cation exchanged with samarium and its catalytic influence in cumene cracking reaction is investigated. Effect of exchange with sodium ions on further exchange with samarium ions is also noted. Acidity measurements are done using TPD of ammonia. The retention of basic structure is proved from FTIR spectra and XRD patterns. Elemental analysis result shows that samarium exchange has occurred, which is responsible for the higher catalytic activity. Surface area and pore volume remains more or less unaffected upon exchange. Thermogravimetric analysis indicates the enhanced thermal stability on exchanging. Cumene cracking reaction is carried out at atmospheric pressure in a fixed bed glass reactor at 673 K. The predominance of Bronsted acidity is confirmed from high selectivity to benzene. (author)

  19. Montmorillonite based artificial nacre prepared via a drying process

    International Nuclear Information System (INIS)

    Bennadji-Gridi, Fayza; Smith, Agnes; Bonnet, Jean-Pierre

    2006-01-01

    Taking advantage of the specific behaviour of Na/Ca montmorillonite in aqueous dispersion, textured films were prepared by progressive evaporation of dispersions with low concentrations of delaminated platelets. The increase of the concentration of ions during evaporation changes the nature of the clay mineral platelet face interactions from repulsive to attractive. After complete drying, a dense brick-like structure is obtained when a sodium salt is used as deflocculant. The bending strength of the textured film is strongly affected by cracks formation during drying, specially when the sample thickness increases. After optimisation, crack-free textured samples with a 140 μm thickness, 20 cm x 25 cm area and 120 MPa bending strength were obtained

  20. Survival of microorganisms in smectite clays - Implications for Martian exobiology

    Science.gov (United States)

    Moll, Deborah M.; Vestal, J. R.

    1992-01-01

    The survival of Baccillus subtilis, Azotobacter chroococcum, and the enteric bacteriophage MS2 has been examined in clays representing terrestrial (Wyoming type montmorillonite) and Martian (Fe3+ montmorillonite) soils exposed to terrestrial and Martian environmental conditions of temperature and atmospheric composition and pressure. An important finding is that MS2 survived simulated Mars conditions better than the terrestrial environment, probably owing to stabilization of the virus caused by the cold and dry conditions of the simulated Mars environment. This finding, the first published indication that viruses may be able to survive in Mars-type soils, may have important implications for future missions to Mars.

  1. Mechanistic examination of pre-exfoliating confinement of surface-active polystyrene nanobeads within pristine clay.

    Science.gov (United States)

    Khvan, Svetlana; Kim, Junkyung; Lee, Sang-Soo

    2007-02-01

    Hydrophobic polymer (PS) nanoparticles preformed through an emulsifier-free emulsion polymerization method were successfully incorporated into a gallery of pristine sodium montmorillonite via interfacial cation exchange. The polymer beads confined between clay nanosheets were capable of (1) preventing the silicate layers from restacking and (2) maintaining the exfoliated state of clay. The increase in the abundance of surface groups promoted adsorption of the nanobeads onto the silicate surface and eventually led to the establishment of strong polymer-clay interactions. These findings suggest that, on the basis of the obtained pre-exfoliated clay masterbatch, the presence of strong polymer-clay interactions could improve the mechanical performance of nanocomposites.

  2. Experimental design applied optimization of a state in epoxy clay dispersion

    International Nuclear Information System (INIS)

    Paz, Juliana D'Avila; Bertholdi, Jonas; Folgueras, Marilena Valadares; Pezin, Sergio Henrique; Coelho, Luiz Antonio Ferreira

    2010-01-01

    This paper presents some analysis showed that the exfoliation / intercalation of a montmorillonite clay in epoxy resin such as viscosity, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetry (TG). Increasing the viscosity of epoxy resin diglycidyl ether bisphenol A with the addition of clay associated with the sonification system at the time of dispersion is a good indication of exfoliation. The X-ray diffraction already cured composite shows a decrease of crystallinity of clay and EDS microanalysis of SEM, non-uniform dispersion of clay in epoxy resin. Thermal analysis TG composite clay / epoxy shows an increase in thermal stability relative to pure epoxy. (author)

  3. Effect of organo clay addition on thermal properties of poly lactide/ polycaprolactone (PLA/ PCL) nano composites

    International Nuclear Information System (INIS)

    Siti Zulaiha Hairaldin; Wan Md Zin Wan Yunus; Norazoma Ibrahim

    2010-01-01

    In this study, melt blending technique was applied to prepare poly lactide/polycaprolactone (PLA/ PCL) nano composites with various blends. Montmorillonite (MMT) was used as an addition to the matrix. In this study, melt blending technique was applied to prepare poly lactide/polycaprolactone (PLA/ PCL) nano composites. Montmorillonite (MMT) was used as an addition to the matrix with various percentages. The other one is modified clay prepared by modifying the nature of montmorillonite with octadecylamine (ODA) to improve the characteristic of PLA/ PCL blends. X-ray diffraction (XRD) results indicated intercalation of the PLA/ PCL into silicate nano size interlayers galleries of the nano composites. The presence of modified clays in nano composite was confirmed by FTIR spectrum. TGA and DTG results show addition of MMT and modified clay ODA-MMT improved the thermal stability of the PLA/ PCL blends. (author)

  4. The Paleo-environmental significance of the iron-formations and iron-rich mudstones of the Mesoarchean Witwatersrand-Mozaan Basin, South Africa

    OpenAIRE

    2009-01-01

    M.Sc. The Mesoarchean Witwatersrand and Pongola Supergroups of South Africa are the oldest, well preserved supracratonic successions worldwide. Various banded iron formation (BIF) and iron-rich mudstone units occur within the West Rand Group of the Witwatersrand Supergroup and the Mozaan Group of the Pongola Supergroup. A granular iron formation (GIF) occurs in a single unit in the Nconga Formation of the Mozaan Group. The Witwatersrand Supergroup and Mozaan Group have been lithostratigrap...

  5. Rapid Separation of Copper Phase and Iron-Rich Phase From Copper Slag at Low Temperature in a Super-Gravity Field

    Science.gov (United States)

    Lan, Xi; Gao, Jintao; Huang, Zili; Guo, Zhancheng

    2018-06-01

    A novel approach for quickly separating a metal copper phase and iron-rich phase from copper slag at low temperature is proposed based on a super-gravity method. The morphology and mineral evolution of the copper slag with increasing temperature were studied using in situ high-temperature confocal laser scanning microscopy and ex situ scanning electron microscopy and X-ray diffraction methods. Fe3O4 particles dispersed among the copper slag were transformed into FeO by adding an appropriate amount of carbon as a reducing agent, forming the slag melt with SiO2 at low temperature and assisting separation of the copper phase from the slag. Consequently, in a super-gravity field, the metallic copper and copper matte were concentrated as the copper phase along the super-gravity direction, whereas the iron-rich slag migrated in the opposite direction and was quickly separated from the copper phase. Increasing the gravity coefficient (G) significantly enhanced the separation efficiency. After super-gravity separation at G = 1000 and 1473 K (1200 °C) for 3 minutes, the mass fraction of Cu in the separated copper phase reached 86.11 wt pct, while that in the separated iron-rich phase was reduced to 0.105 wt pct. The recovery ratio of Cu in the copper phase was as high as up to 97.47 pct.

  6. Insights into the Structure and Metabolic Function of Microbes That Shape Pelagic Iron-Rich Aggregates ( Iron Snow )

    Energy Technology Data Exchange (ETDEWEB)

    Lu, S [Friedrich Schiller University Jena, Jena Germany; Chourey, Karuna [ORNL; REICHE, M [Friedrich Schiller University Jena, Jena Germany; Nietzsche, S [Friedrich Schiller University Jena, Jena Germany; Shah, Manesh B [ORNL; Hettich, Robert {Bob} L [ORNL; Kusel, K [Friedrich Schiller University Jena, Jena Germany

    2013-01-01

    Metaproteomics combined with total nucleic acid-based methods aided in deciphering the roles of microorganisms in the formation and transformation of iron-rich macroscopic aggregates (iron snow) formed in the redoxcline of an acidic lignite mine lake. Iron snow had high total bacterial 16S rRNA gene copies, with 2 x 109 copies g (dry wt)-1 in the acidic (pH 3.5) central lake basin and 4 x 1010 copies g (dry wt)-1 in the less acidic (pH 5.5) northern lake basin. Active microbial communities in the central basin were dominated by Alphaproteobacteria (36.6%) and Actinobacteria (21.4%), and by Betaproteobacteria (36.2%) in the northern basin. Microbial Fe-cycling appeared to be the dominant metabolism in the schwertmannite-rich iron snow, because cloning and qPCR assigned up to 61% of active bacteria as Fe-cycling bacteria (FeB). Metaproteomics revealed 70 unique proteins from central basin iron snow and 283 unique proteins from 43 genera from northern basin. Protein identification provided a glimpse into in situ processes, such as primary production, motility, metabolism of acidophilic FeB, and survival strategies of neutrophilic FeB. Expression of carboxysome shell proteins and RubisCO indicated active CO2 fixation by Fe(II) oxidizers. Flagellar proteins from heterotrophs indicated their activity to reach and attach surfaces. Gas vesicle proteins related to CO2-fixing Chlorobium suggested that microbes could influence iron snow sinking. We suggest that iron snow formed by autotrophs in the redoxcline acts as a microbial parachute, since it is colonized by motile heterotrophs during sinking which start to dissolve schwertmannite.

  7. Molecular Simulation Study of Montmorillonite in Contact with Variably Wet Supercritical Carbon Dioxide

    KAUST Repository

    Kadoura, Ahmad Salim

    2017-03-07

    We perform grand canonical Monte Carlo simulations to study the detailed molecular mechanism of intercalation behavior of CO2 in Na-, Ca-, and Mg- montmorillonite exposed to variably hydrated supercritical CO2 at 323.15 K and 90 bar, The simulations indicate that the intercalation of CO2 strongly depends on the relative humidity (RH). The intercalation of CO2 in the dehydrated interlayer is inhibited, followed by the swelling of the interlayer region due to uptake of water and CO2 as the RH increases. In all of the hydrated clay samples, the amount of the intercalated CO2 generally decreases as a function of increasing RH, which is attributed mainly to the weakening of the interaction between CO2 and clay. At low RH values, Ca- and Mg- montmorillonite are relatively more efficient in capturing CO2. The amount of CO2 trapped in all clay samples shows similar values above RH of similar to 60%. Molecular dynamics simulations show that the diffusion coefficient of each species generally increases with increasing RH due to the associated expansion of the interlayer distance of the clay. For all the hydrated samples, the diffusion coefficients of CO2 and water in the interlayers are mostly comparable due to the fact that CO2 molecules are well solvated. The diffusion of CO2 in each hydration state is mostly independent of the type of cation in accordance with the fact that CO2 molecules hardly migrate into the first hydration shell of the interlayer cations.

  8. PREPARATION AND CATALYTIC ACTIVITY FOR ISOPROPYL BENZENE CRACKING OF Co, Mo AND Co/Mo-Al2O3-PILLARED MONTMORILLONITE CATALYSTS

    Directory of Open Access Journals (Sweden)

    Hasanudin Hasanudin

    2010-06-01

    Full Text Available It has been prepared Co, Mo and Co/Mo-Al2O3-pillared montmorillonite catalysts using montmorillonite clay  as raw material. The structure and porosity of the catalysts were determined using N2 adsorption-desorption and FT-IR spectroscopy analysis methods. Isopropyl benzene cracking using these catalysts were used to test the catalytic activity and performance of Co, Mo and Co/Mo-Al2O3-pillared montmorillonites.  Characterization results showed that pillarization resulted in the increase of the total pore volume and specific surface area of the clay. Meanwhile, transition metals (Co, Mo and Co/Mo loaded on Al2O3-pillared monmorillonites could increase the catalytic activity of the catalysts for isopropyl benzene cracking significantly.   Keywords: pillared monmorillonite, isopropyl benzene  and cracking catalyst

  9. Osmotic pressure in Ca/Na montmorillonite dispersions: Monte Carlo simulations

    International Nuclear Information System (INIS)

    Joensson, Bo; Aakesson, T.; Segad, M.; Cabane, B.

    2010-01-01

    Document available in extended abstract form only. In the past, clay-water systems have been extensively studied. due to its importance in agricultural as well as technological applications. A more recent use of clay is as sealing material for nuclear waste. The success for such a containment depends on the clay structure and its swelling properties. This means that the clay should be able to sustain considerable changes in the surrounding ground water including salinities of glacial melt water as well as sea water, while still being an effective hydraulic barrier. We have approached this problem using statistical mechanical simulation techniques. The osmotic pressure in Ca/Na montmorillonite dispersions has been calculated via Monte Carlo simulations. For a clay system in equilibrium with pure water, Monte Carlo simulations predict a large swelling when the clay counterions are monovalent, while in presence of divalent counterions a limited swelling is predicted with an aqueous layer between the clay lamellae of about 1 nm - in excellent agreement with SAXS data. Montmorillonite in contact with a salt reservoir with e.g. both Na and Ca counterions will only show a modest swelling unless the Na + concentration in the bulk is several orders of magnitude larger than the Ca 2+ concentration. This is true both for a clay repository surrounded by ground water as well as sea water of high salinity. The limited swelling of clay in presence of divalent counterions is a consequence of ion-ion correlations, which both reduce the entropic repulsion and give rise to an attractive component in the total osmotic pressure. Ion-ion correlations also favour divalent counterions when competing with monovalent ones. This is an important aspect for the retention of radioactive charged species. A more fundamental result of ion-ion correlations is that the osmotic pressure as a function of clay sheet separation becomes non-monotonic - which indicates the possibility of a phase

  10. montmorillonite nanocomposite containing n,n

    African Journals Online (AJOL)

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    The effect of clay dispersion and the interaction between clay and polymeric chains on the ... modified with an intercalating agent to obtain organically modified clay prior ... performance polymers materials for several applications such as high ...

  11. Influence of Polymer-Clay Interfacial Interactions on the Ignition Time of Polymer/Clay Nanocomposites.

    Science.gov (United States)

    Zope, Indraneel S; Dasari, Aravind; Yu, Zhong-Zhen

    2017-08-11

    Metal ions present on smectite clay (montmorillonite) platelets have preferential reactivity towards peroxy/alkoxy groups during polyamide 6 (PA6) thermal decomposition. This changes the decomposition pathway and negatively affects the ignition response of PA6. To restrict these interfacial interactions, high-temperature-resistant polymers such as polyetherimide (PEI) and polyimide (PI) were used to coat clay layers. PEI was deposited on clay by solution-precipitation, whereas PI was deposited through a solution-imidization-precipitation technique before melt blending with PA6. The absence of polymer-clay interfacial interactions has resulted in a similar time-to-ignition of PA6/PEI-clay (133 s) and PA6/PI-clay (139 s) composites as neat PA6 (140 s). On the contrary, PA6 with conventional ammonium-based surfactant modified clay has showed a huge drop in time-to-ignition (81 s), as expected. The experimental evidences provided herein reveal the role of the catalytic activity of clay during the early stages of polymer decomposition.

  12. Aggregation and transport of rutile titanium dioxide nanoparticles with montmorillonite and diatomite in the presence of phosphate in porous sand.

    Science.gov (United States)

    Guo, Peng; Xu, Nan; Li, Duo; Huangfu, Xinxing; Li, Zuling

    2018-08-01

    Crop soil is inevitably contaminated by the excess of phosphate (P) fertilizers. A large amount of nanoparticle titanium dioxide (nTiO 2 ) entered soils as well due to the wide use of engineered nanomaterials. It is of great urgency and a high priority to investigate the mechanisms of nTiO 2 deposition with the presence of P in crop soils. This study investigated the transport behavior of (1.0 g L -1 ) rutile nTiO 2 with two representative clay particles (montmorillonite or diatomite) in the presence of P through the saturated quartz sand. In 10 mM NaCl electrolyte solution at pH 6.0, the recovery percentage of nTiO 2 was 36.3% from sand column. Nevertheless, it was reduced to 18.6% and 11.1% while montmorillonite and diatomite present in suspensions, respectively. Obviously, the improvement of nTiO 2 retention in sand was more pronounced by diatomite than montmorillonite. The likely mechanism for this result was that large aggregates were formed due to the attachment of nTiO 2 to montmorillonite and diatomite. Moreover, the surface of diatomite with the larger hydrodynamic radius was less negatively charged by comparison with montmorillonite. However, this phenomenon disappeared with the addition of P. P adsorption increases the repulsive force between particles and sand and the fast release of attached nTiO 2 -montmorillonite and diatomite from sand. The two-site kinetic retention model and the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory suggested that the combination of k 1/ k 1d , k 2 and secondary minimum energy can be used to accurately describe the attachment of nTiO 2 -montmorillonite and diatomite to sand in the presence of P. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Synchrotron SAXS/WAXD and rheological studies of clay suspensions in silicone fluid.

    Science.gov (United States)

    Zhang, Li-Ming; Jahns, Christopher; Hsiao, Benjamin S; Chu, Benjamin

    2003-10-15

    Suspensions of two commercial smectite clays, montmorillonite KSF and montmorillonite K10, in a low-viscosity silicone oil (Dow Corning 245 Fluid) were studied by simultaneous synchrotron small-angle X-ray scattering (SAXS)/wide-angle X-ray diffraction (WAXD) techniques and rheological measurements. In the 0.5% (w/v) KSF clay suspension and two K10 clay suspensions (0.5% and 1.0%), WAXD profiles below 2theta=10.0 degrees did not display any characteristic reflection peaks associated with the chosen montmorillonite clays, while corresponding SAXS profiles exhibited distinct scattering maxima, indicating that both clays were delaminated by the silicone oil. In spite of the large increase in viscosity, the clay suspensions exhibited no gel characteristics. Dynamic rheological experiments indicated that the clay/silicone oil suspensions exhibited the behavior of viscoelasticity, which could be influenced by the type and the concentration of the clay. For the K10 clay suspensions, the frequency-dependent loss modulus (G") was greater in magnitude than the storage modulus (G') in the concentration range from 0.5 to 12.0%. The increase in the clay concentration shifted the crossover point between G' and G" into the accessible frequency range, indicating that the system became more elastic. In contrast, the KSF clay suspension exhibited lower G' and G" values, indicating a weaker viscoelastic response. The larger viscoelasticity response in the K10 clay suspension may be due to the acid treatment generating a higher concentration of silanol groups on the clay surface.

  14. Ag-Coated Heterostructures of ZnO-TiO2/Delaminated Montmorillonite as Solar Photocatalysts

    Directory of Open Access Journals (Sweden)

    Carolina Belver

    2017-08-01

    Full Text Available Heterostructures based on ZnO-TiO2/delaminated montmorillonite coated with Ag have been prepared by sol–gel and photoreduction procedures, varying the Ag and ZnO contents. They have been thoroughly characterized by XRD, WDXRF, UV–Vis, and XPS spectroscopies, and N2 adsorption, SEM, and TEM. In all cases, the montmorillonite was effectively delaminated with the formation of TiO2 anatase particles anchored on the clay layer’s surface, yielding porous materials with high surface areas. The structural and textural properties of the heterostructures synthesized were unaffected by the ZnO incorporated. The photoreduction led to solids with Ag nanoparticles decorating the surface. These materials were tested as photocatalysts for the degradation of several emerging contaminants with different nitrogen-bearing chemical structures under solar light. The catalysts yielded high rates of disappearance of the starting pollutants and showed quite stable performance upon successive applications.

  15. Temperature effect on the acid-base behaviour of Na-montmorillonite.

    Science.gov (United States)

    Duc, Myriam; Carteret, Cédric; Thomas, Fabien; Gaboriaud, Fabien

    2008-11-15

    We report a study of the acid-base properties of Na-montmorillonite suspensions at temperatures from 25 degrees C to 80 degrees C, by continuous and batch potentiometric methods, combined with analysis of the dissolved and readsorbed species. The batch titration curves reveal that the dissolution processes of Na-montmorillonite and silica-rich secondary phases are increasingly predominant, respectively at acid and basic pH, and according to the temperature. The continuous titration curves are less affected by these side reactions. In the absence of a common intersection point, the thermodynamic analysis of the curves was based on the shift of the PZNPC with the ionic strength. This shift was not significantly altered by the temperature, by comparison with the dissociation product of water in the same conditions. Therefore we concluded that protonation-deprotonation of the dissociable sites at the edges of the clay platelets is not significantly temperature dependent.

  16. Hyperspectral analysis of clay minerals

    Science.gov (United States)

    Janaki Rama Suresh, G.; Sreenivas, K.; Sivasamy, R.

    2014-11-01

    A study was carried out by collecting soil samples from parts of Gwalior and Shivpuri district, Madhya Pradesh in order to assess the dominant clay mineral of these soils using hyperspectral data, as 0.4 to 2.5 μm spectral range provides abundant and unique information about many important earth-surface minerals. Understanding the spectral response along with the soil chemical properties can provide important clues for retrieval of mineralogical soil properties. The soil samples were collected based on stratified random sampling approach and dominant clay minerals were identified through XRD analysis. The absorption feature parameters like depth, width, area and asymmetry of the absorption peaks were derived from spectral profile of soil samples through DISPEC tool. The derived absorption feature parameters were used as inputs for modelling the dominant soil clay mineral present in the unknown samples using Random forest approach which resulted in kappa accuracy of 0.795. Besides, an attempt was made to classify the Hyperion data using Spectral Angle Mapper (SAM) algorithm with an overall accuracy of 68.43 %. Results showed that kaolinite was the dominant mineral present in the soils followed by montmorillonite in the study area.

  17. Aflatoxin B1 adsorption by the natural aluminosilicates - concentrate of montmorillonite and zeolite

    Directory of Open Access Journals (Sweden)

    Marković Marija A.

    2016-01-01

    Full Text Available Aflatoxin B1 adsorption by the concentrate of bentonite clay - montmorillonite and the natural zeolite - clinoptilolite and was investigated at the initial toxin concentration 4 ppm, with different amonunts of solid phase in suspension (10, 5, 2 and 1 mg/10 mL and different pH values - 3, 7 and 9. Results indicated that for both minerals, decreasing the amount of solid phase in suspension, decrease the amount of active sites relevant for adsorption of aflatoxin B1. Thus, for concentrate of montnorillonite, at the lowest level of solid phase in suspension (1 mg/10 mL, aflatoxin B1 adsorption indexes were 97% at pH 3, 88% at pH 7 and 82% at pH 9, while for the natural zeolite, adsorption of toxin was 9% at pH 3 and 7% at pH 7 and 9. Since inorganic cations in minerals are mainly responsible for aflatoxin B1 adsorption, even the natural zeolite - clinoptilite has much higher cation exchange capacity (the content of inorganic exchangeable cations compared to the concentrate of montmorillonite, adsorption of aflatoxin B1 by this mineral is much lower. Comparing the molecular dimensions of aflatoxin B1 molecule with the dimension of channels of clinoptilolite and interlamellar space of montmorillonite it is obvious that this toxin is adsorbed only at the external surface of clinoptilolite while in the montmorillonite all active sites are equally available for its adsorption. Thus, the concentrate of montmorillonite posess by higher adsorption capacity for aflatoxin B1. Results presented in this paper confirmed the fact the differences in the structure of minerals led to their different efficiency for adsorption of aflatoxin B1. Mineralogical and chemical composition, determination of cation exchange capacity, etc., are very important parameters influencing the effectiveness of minerals as aflatoxin B1 adsorbents. [Projekat Ministarstva nauke Republike Srbije, br. 451-03-2802-IP Tip1/142, br. 172018 i br. 34013

  18. Hexadimethrine-montmorillonite nanocomposite: Characterization and application as a pesticide adsorbent

    International Nuclear Information System (INIS)

    Gámiz, B.; Hermosín, M.C.; Cornejo, J.; Celis, R.

    2015-01-01

    Graphical abstract: - Highlights: • Characterization of hexadimethrine-montmorillonite nanocomposite was appraised. • Comparative studies with traditional HDTMA-montmorillonite were performed. • We investigated the pesticide adsorption mechanisms displayed by the nanocomposites. • Hexadimethrine-nanocomposite showed selective affinity for anionic pesticides. - Abstract: The goal of this work was to prepare and characterize a novel functional material by the modification of SAz-1 montmorillonite with the cationic polymer hexadimethrine (SA-HEXAD), and to explore the potential use of this nanocomposite as a pesticide adsorbent. Comparative preparation and characterization with the well-known hexadecyltrimethylammonium-modified SAz-1 montmorillonite (SA-HDTMA) was also assessed. The characterization was performed by elemental analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), physisorption of N 2 , scanning electron microscopy (SEM) and Z potential measurements. The characterization and adsorption experiments showed that the extent of pesticide adsorption was markedly subjected to the structure and features of the surface of each organo-clay and also to the nature of the considered pesticide. SA-HEXAD displayed a high affinity for anionic pesticides which, presumably, were adsorbed by electrostatic attraction on positively-charged ammonium groups of the polymer not directly interacting with the clay. In contrast, SA-HDTMA displayed great adsorption of both uncharged and anionic pesticides with predominance of hydrophobic interactions. This work provided information about the surface properties of a new organic–inorganic nanohybrid material, SA-HEXAD, and its potential as an adsorbent for the removal of anionic organic pollutants from aqueous solutions

  19. Microbial mineral illization of montmorillonite in low-permeability oil reservoirs for microbial enhanced oil recovery.

    Science.gov (United States)

    Cui, Kai; Sun, Shanshan; Xiao, Meng; Liu, Tongjing; Xu, Quanshu; Dong, Honghong; Wang, Di; Gong, Yejing; Sha, Te; Hou, Jirui; Zhang, Zhongzhi; Fu, Pengcheng

    2018-05-11

    Microbial mineral illization has been investigated for its role in the extraction and recovery of metals from ores. Here we report our application of mineral bioillization for the microbial enhanced oil recovery in low-permeability oil reservoirs. It aimed to reveal the etching mechanism of the four Fe (III)-reducing microbial strains under anaerobic growth conditions on the Ca-montmorillonite. The mineralogical characterization of the Ca-montmorillonite was performed by Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy and energy dispersive spectrometer. Results showed that the microbial strains could efficiently reduce Fe (III) at an optimal rate of 71 %, and alter the crystal lattice structure of the lamella to promote the interlayer cation exchange, and to efficiently inhibit the Ca-montmorillonite swelling at an inhibitory rate of 48.9 %. Importance Microbial mineral illization is ubiquitous in the natural environment. Microbes in low-permeability reservoirs are able to enable the alteration of the structure and phase of the Fe-poor minerals by reducing Fe (III) and inhibiting clay swelling which is still poorly studied. This study aimed to reveal the interaction mechanism between Fe (III)-reducing bacterial strains and Ca-montmorillonite under anaerobic atmosphere, and to investigate the extent and rates of Fe (III) reduction and phase changes with their activities. Application of Fe (III)-reducing bacteria will provide a new way to inhibit clay swelling, to elevate reservoir permeability, and to reduce pore throat resistance after water flooding for enhanced oil recovery in low-permeability reservoirs. Copyright © 2018 American Society for Microbiology.

  20. Effect of pH on the adsorption of dodecylamine on montmorillonite: Insights from experiments and molecular dynamics simulations

    Science.gov (United States)

    Peng, Chenliang; Min, Fanfei; Liu, Lingyun

    2017-12-01

    The hydrophobic aggregation in cationic surfactant suspension is an effective method to enhance the dewatering of clay-rich tailing. The solution pH can affect the adsorption behavior of cationic surfactant on clay mineral. The effect of pH on the adsorption of dodecylamine (DDA) on montmorillonite was investigated by the sedimentation test and the characterization of flocs images, contact angle, adsorption quantity, and fourier transform infrared (FTIR) spectroscopy, as well as molecular dynamics (MD) simulation. It was found that DDA ions were adsorbed on montmorillonite basal surfaces mainly by physical adsorption, including the electrostatic attraction and hydrogen bonding. A certain number of neutral DDA molecules can favor the adsorption of DDA. At pH around 8, the effect of hydrophobic modification was the best because DDA molecules and ions form compact and well-organized monolayer. The MD simulation results were in good agreement with that of contact angle, adsorption quantity and FTIR.

  1. Structural characterization of clays commercially used in red ceramics

    International Nuclear Information System (INIS)

    Brito, E.M.; Moura, J.K.L.; Souza, R.B.; Brandim, A.S.

    2014-01-01

    The use of clays hills being an alternative to clay floodplain, due to environmental protection laws. The research project aims at the morphological and chemical characterization of hills clays used industrially for the production of ceramic tiles and blocks. Therefore, two types of methods were known commercially in the region of Teresina-PI through diffraction of X-rays (X-DR), scanning electron microscopy (SEM) and energy dispersive spectrometry X-ray (EDS). It can be observed that the samples have a high percentage of quartz, hematite still having in its constitution aluminum oxide, zirconium oxide and titanium oxide. The results show that the clays are clays and montmorillonites may be used for the production of ceramic tiles and blocks, but as the proportion of using the same will be focusing the next job. (author)

  2. The effect of dispersion technique of montmorillonite on polyisocyanurate nanocomposites

    Science.gov (United States)

    Cabulis, U.; Fridrihsone, A.; Andersons, J.; Vlcek, T.

    2014-05-01

    The biomass represents an abundant, renewable, competitive and low cost resource that can play an alternative role to petrochemical resources. The central topic of the research activity reported is the use of rape seed oil (RO) as a raw material for the production of rigid polyisocyanurate foams (PIR). The content of the renewable resource-derived polymers achieved in ready foams is up to 20%. By using biopolymers as a matrix, a prospective way is to reinforce them with nanoparticles, organically modified clays, for improvement of mechanical properties while, at the same time, replacing petrochemical raw materials. Organoclay Cloisite® 15A was tested as a filler of PIR foams. Three different techniques - ultrasonification, mixing by three-roll mills, and high-pressure homogenization were used for dispergation of nanoclays in polyols. Composite polyisocyanurate foams and solid polymer samples were produced and tested for stiffness and strength. This paper discusses the studies into the use of RO as a renewable source in rigid PIR foams filled with organomodified montmorillonite clay with loadings from 1 to 5% by weight.

  3. Soil clay content underlies prion infection odds

    Science.gov (United States)

    David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

    2011-01-01

    Environmental factors-especially soil properties-have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  4. Effects of modified Clay on the morphology and thermal stability of PMMA/clay nanocomposites

    International Nuclear Information System (INIS)

    Tsai, Tsung-Yen; Lin, Mei-Ju; Chuang, Yi-Chen; Chou, Po-Chiang

    2013-01-01

    The potential to improve the mechanical, thermal, and optical properties of poly(methyl methacrylate) (PMMA)/clay nanocomposites prepared with clay containing an organic modifier was investigated. Pristine sodium montmorillonite clay was modified using cocoamphodipropionate, which absorbs UVB in the 280–320 nm range, via ion exchange to enhance the compatibility between the clay platelets and the methyl methacrylate polymer matrix. PMMA/clay nanocomposites were synthesized via in situ free-radical polymerization. Three types of clay with various cation-exchange capacities (CEC) were used as inorganic layered materials in these organic–inorganic hybrid nanocomposites: CL42, CL120, and CL88 with CEC values of 116, 168, and 200 meq/100 g of clay, respectively. We characterized the effects of the organoclay dispersion on UV resistance, effectiveness as an O 2 gas barrier, thermal stability, and mechanical properties of PMMA/clay nanocomposites. Gas permeability analysis demonstrated the excellent gas barrier properties of the nanocomposites, consistent with the intercalated or exfoliated morphologies observed. The optical properties were assessed using UV–Visible spectroscopy, which revealed that these materials have good optical clarity, UV resistance, and scratch resistance. The effect of the dispersion capability of organoclay on the thermal properties of PMMA/clay nanocomposites was investigated by thermogravimetric analysis and differential scanning calorimetry; these analyses revealed excellent thermal stability of some of the modified clay nanocomposites. - Highlights: ► We control the dispersion morphology by protonation of K2 into the clay. ► The CL120 and CL88, with the higher CEC, are more random intercalated by K2. ► We report these materials have good optical clarity, and UV resistance

  5. Absorption characteristics of Kupravas deposit clays modified by phosphoric acid

    International Nuclear Information System (INIS)

    Ruplis, A.; Mezinskis, G.; Chaghuri, M.

    1998-01-01

    Literature data suggested that clays may be used as sorbents for waste water treatment. The surface and sorption properties of minerals changes due to the influence of acid rains. The process of recession of clay properties has been modeled in laboratory by treatment of clays with mineral acids at higher temperature that in natural conditions. The present paper is devoted to the study of influence of phosphoric acid on the sorption properties of Kupravas deposit clays. Natural clay samples and samples treated with phosphoric acid were characterized by means of x-ray diffraction an differential thermal analysis (DTA) methods These methods were used also to identify the sample of Lebanese clays. X-ray diffraction analysis data show that the samples of clays from the deposit of Kuprava contain illite and kaolinite while sample of Lebanese clay contains quartz, calcite, and montmorillonite. DTA results show characteristic features of Kuprava clays described in reference with DTA of Lebanese clay clearly demonstrate the presence of large quantity of calcite

  6. Characterization of poly pyrrole/montmorillonite electro polymerised onto Pt; Caracterizacao de filmes PPy/montmorilonita eletropolimerizados sobre Pt

    Energy Technology Data Exchange (ETDEWEB)

    Castagno, K.R.L., E-mail: katiarlc@pelotas.ifsul.edu.b [Instituto Federal Sul-rio-grandense (IFSul), RS (Brazil). Dept. de Quimica; Azambuja, D.S.; Dalmoro, V.; Mauller, R.S. [Universidade Federal do Rio Grande do Sul (UFRGS), Pelotas, RS (Brazil). Inst. de Quimica

    2010-07-01

    In this study films of polypyrrole/montmorillonite (PPy/MT) were electropolymerized on platinum in order to evaluate the performance of this technique in the preparation of nanocomposite materials and to determine the thermal properties and conductivity of the composites. The films were synthesized from a solution containing pyrrole, dodecylbenzene sulfonate, acid and two types of clays: montmorillonite-Na + (MT-Na) and montmorillonite-30B (MT-M). The characterization of the films we have used FT-IR, TEM, XRD, TGA, DSC and resistivity measurement by the four-point van der Pauw method. The study showed that the adopted method of exfoliation and the electropolymerization method used, allows obtaining nanocomposite materials. Analyses of FT-IR, TEM and XRD show that the clays are exfoliated in the polymer matrix. Thermal analysis of the films indicates that the addition of clay reflects an enhancement in the thermal properties of the matrix of PPy, but decreases the conductivity of the same. (author)

  7. Sustainability of the effects of medicinal iron and iron rich food supplementation on haemoglobin, intelligence quotient and growth of school aged girls

    Directory of Open Access Journals (Sweden)

    Monika Jain

    2014-12-01

    Full Text Available Anaemia in school aged girls is an important but neglected issue. Since iron supplementation programmes have had little reported success in reducing anaemia, interest is turning to food based approaches that have higher potential for achieving far reaching benefits. The purpose of the study was to observe sustainability of the effect of iron and food supplementation on haemoglobin (Hb, intelligence quotient (IQ and growth of the subjects. At baseline, estimation of haemoglobin (Hb, red cell indices, serum iron, total iron binding capacity, serum transferrin saturation and serum ferritin was done. IQ, weight and height were measured using standard procedures. Anaemic subjectswere divided into three groups, viz., (i twice weekly supplementation of iron folic acid syrup (53 mg iron/week; (ii daily supplementation of 4 niger seed and defatted soyaflour biscuits plus 2 lemons (45 mg iron/week and (iii control. Non anaemic group(NAC was not intervened. Endline data was collected after 120 days. Follow up for Hb, IQ, weight and height was done 4 months after cessation of supplementation. The prevalence of anaemia was 77% in the study population; 46% subjects had mild anaemia and 32% had moderate anaemia. Iron status was lower in anaemic subjects (p<0.001.Iron supplementation was more effective in raising Hb and building iron stores than iron rich food supplementation. Iron supplementation improved IQ but did not bring about catch up of anaemics to non anaemics. Iron rich food supplementation was better than medicinal iron in promoting growth in anaemic girls. The impact of iron rich food supplementation on Hb, IQ and growth sustained for 4 months while that of medicinal iron did not. Effects of food supplementation are sustainable for 4 months, therefore, this strategy holds more potential to control anaemia, in school aged girls.

  8. Clay intercalation and influence on crystallinity of EVA-based clay nanocomposites

    International Nuclear Information System (INIS)

    Chaudhary, D.S.; Prasad, R.; Gupta, R.K.; Bhattacharya, S.N.

    2005-01-01

    Various polymer clay nanocomposites (PCNs) were prepared from ethylene vinyl acetate copolymer (EVA) with 9, 18 and 28% vinyl acetate (VA) content filled with different wt.% (2.5, 5 and 7.5) of a Montmorillonite-based organo-modified clay (Cloisite[reg] C15A and C30B). The PCNs were prepared using melt blending techniques. Morphological information regarding intercalation and exfoliation were determined by using wide-angle X-ray scattering (WAXS) and transmission electron microscopy (TEM). WAXS and TEM confirmed that increasing the VA content was necessary to achieve greater clay-polymer interaction as seen from the comparatively higher intercalation of clay platelets with 28% VA. The effect of addition of clay on the development and the modification of crystalline morphology in EVA matrix was also studied using WAXS and temperature-modulated differential scanning calorimetry (MDSC). Results are presented showing that the addition of clay platelets does not increase the matrix crystallinity but the morphology was significantly modified such that there was an increase in the 'rigid' amorphous phase. Mechanical properties were also evaluated against the respective morphological information for each specimen and there are indications that the level of clay-polymer interaction plays a significant role in such morphological modification, and in such a way that affects the final PCN mechanical properties which has wide and significant applications in the packaging industries

  9. Electrospun composite matrices of poly(ε-caprolactone)-montmorillonite made using tenside free Pickering emulsions

    International Nuclear Information System (INIS)

    Samanta, Archana; Takkar, Sonam; Kulshreshtha, Ritu; Nandan, Bhanu; Srivastava, Rajiv K.

    2016-01-01

    The production of composite electrospun matrices of poly(ε-caprolactone) (PCL) using an emulsifier-free emulsion, made with minimal organic solvent, as precursor is reported. Pickering emulsions of PCL were prepared using modified montmorillonite (MMT) clay as the stabilizer. Hydrophobic tallow group of the modified MMT clay resulted in analogous interaction of clay with oil and aqueous phase and its adsorption at the interface to provide stability to the resultant emulsion. Composite fibrous matrices of PCL and MMT were produced using electrospinning under controlled conditions. The fiber fineness was found to alter with PCL concentration and volume fraction of the aqueous and oil phases. A higher tensile strength and modulus was obtained with inclusion of MMT in PCL electrospun matrix in comparison to a matrix made using neat PCL. The presence of clay in the fibrous matrix did not change the cell proliferation efficiency in comparison to neat PCL matrix. Composite fibrous matrices of PCL/MMT bearing enhanced tensile properties may find applications in areas other than tissue engineering for example food packaging and filtration. - Highlights: • Tenside free, clay stabilized Pickering emulsion of PCL is made with minimal organic solvent. • Organic–inorganic composite fibrous matrices were produced via emulsion electrospinning. • Fiber fineness was efficiently controlled by variation in emulsion formulation. • Fibrous matrices of high tensile strength and modulus were obtained in comparison to neat PCL matrix. • PCL/clay matrices showed effective cell proliferation as a neat PCL matrix.

  10. Electrospun composite matrices of poly(ε-caprolactone)-montmorillonite made using tenside free Pickering emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Samanta, Archana [Department of Textile Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Takkar, Sonam; Kulshreshtha, Ritu [Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Nandan, Bhanu [Department of Textile Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Srivastava, Rajiv K., E-mail: rajiv@textile.iitd.ac.in [Department of Textile Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India)

    2016-12-01

    The production of composite electrospun matrices of poly(ε-caprolactone) (PCL) using an emulsifier-free emulsion, made with minimal organic solvent, as precursor is reported. Pickering emulsions of PCL were prepared using modified montmorillonite (MMT) clay as the stabilizer. Hydrophobic tallow group of the modified MMT clay resulted in analogous interaction of clay with oil and aqueous phase and its adsorption at the interface to provide stability to the resultant emulsion. Composite fibrous matrices of PCL and MMT were produced using electrospinning under controlled conditions. The fiber fineness was found to alter with PCL concentration and volume fraction of the aqueous and oil phases. A higher tensile strength and modulus was obtained with inclusion of MMT in PCL electrospun matrix in comparison to a matrix made using neat PCL. The presence of clay in the fibrous matrix did not change the cell proliferation efficiency in comparison to neat PCL matrix. Composite fibrous matrices of PCL/MMT bearing enhanced tensile properties may find applications in areas other than tissue engineering for example food packaging and filtration. - Highlights: • Tenside free, clay stabilized Pickering emulsion of PCL is made with minimal organic solvent. • Organic–inorganic composite fibrous matrices were produced via emulsion electrospinning. • Fiber fineness was efficiently controlled by variation in emulsion formulation. • Fibrous matrices of high tensile strength and modulus were obtained in comparison to neat PCL matrix. • PCL/clay matrices showed effective cell proliferation as a neat PCL matrix.

  11. Natural montmorillonite induced photooxidation of As(III) in aqueous suspensions: Roles and sources of hydroxyl and hydroperoxyl/superoxide radicals

    International Nuclear Information System (INIS)

    Wang, Yajie; Xu, Jing; Li, Jinjun; Wu, Feng

    2013-01-01

    Highlights: • Natural montmorillonite contributes to photochemical oxidation of arsenite. • Ferrous ions significantly affect photochemical behavior of montmorillonite. • HO· and HO 2 ·/O 2 − · play different roles in this process. -- Abstract: Photooxidation of arsenite(As(III)) in a suspension of natural montmorillonite under the irradiation of metal halide lamp (λ ≥ 313 nm)has been investigated. The results showed that the natural montmorillonite induced the photooxidation of As(III) by generating hydroxyl radicals (HO·) and hydroperoxyl/superoxide radicals (HO 2 ·/O 2 − ·). HO· which was responsible for the As(III) photooxidation. Approximately 38% of HO· was generated by the photolysis of ferric ions, and the formation of the remaining 62% was strongly dependent on the HO 2 ·/O 2 − ·. The presence of free ironions (Fe 2+ and Fe 3+ ), made significant contributions to the photogeneration of these reactive oxygen species (ROS). The photooxidation of As(III) in natural montmorillonite suspensions was greatly influenced by the pH values. The photooxidation of As(III) by natural montmorillonite followed the Langmuir–Hinshelwood equation. In addition, the photooxidation of As(III) could be enhanced by the addition of humic acid. This work demonstrates that photooxidation may be an important environmental process for the oxidation of As(III) and may be a way to remove As(III) from acidic surface water containing iron-bearing clay minerals

  12. Interstratified Illite/Montmorillonite in Kamojang Geothermal Field, Indonesia

    Directory of Open Access Journals (Sweden)

    D. F. Yudiantoro

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v8i4.167Kamojang geothermal field located in West Java Province, falls under the Pangkalan Subregency, Bandung Regency. The researched area is a geothermal field located in the Quaternary volcanic caldera system of about 0.452 to 1.2 Ma. The volcanic activity generated hydrothermal fluids, interacting with rocks producing mineral alteration. The minerals formed in the areas of research are interstratified illite/montmorillonite (I/M. Analyses to identify interstratified I/M have been performed by X-ray diffraction using ethylene glycol, while the determination of the type and percentage of interstratified I/M was based on the calculation method of Watanabe. The methodology was applied on core and cutting samples from Wells KMJ-8, 9, 11, 13, 16, 23, 49, 51, and 54. The result of analysis of the samples shows that the type of clay is interstratified illite/montmorillonite and the minerals are formed at temperatures ranging from 180 to 220° C. The type of interstratified I/M in the studied area is S = 0 and S = 1. The percentage of illite type S = 0 is between 20 - 35% illite, whereas type S = 1 has about 45 - 72% illite. Along with the increasing depth, the percentage of illite is getting greater. This is consistent with the vertical distribution of temperature which increases according to the depth. This correlation results in an interpretation that the upflow zone of the geothermal reservoir is located in the centre of the Kamojang geothermal field.

  13. Removal of Cr(VI) from Aqueous Environments Using Micelle-Clay Adsorption

    Science.gov (United States)

    Qurie, Mohannad; Khamis, Mustafa; Manassra, Adnan; Ayyad, Ibrahim; Nir, Shlomo; Scrano, Laura; Bufo, Sabino A.; Karaman, Rafik

    2013-01-01

    Removal of Cr(VI) from aqueous solutions under different conditions was investigated using either clay (montmorillonite) or micelle-clay complex, the last obtained by adsorbing critical micelle concentration of octadecyltrimethylammonium ions onto montmorillonite. Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI) from aqueous solutions. Langmuir adsorption isotherm fitted the experimental data giving significant results. Filtration experiments using columns filled with micelle-clay complex mixed with sand were performed to assess Cr(VI) removal efficiency under continuous flow at different pH values. The micelle-clay complex used in this study was capable of removing Cr(VI) from aqueous solutions without any prior acidification of the sample. Results demonstrated that the removal effectiveness reached nearly 100% when using optimal conditions for both batch and continuous flow techniques. PMID:24222757

  14. clay nanocomposites

    Indian Academy of Sciences (India)

    The present work deals with the synthesis of specialty elastomer [fluoroelastomer and poly (styrene--ethylene-co-butylene--styrene (SEBS)]–clay nanocomposites and their structure–property relationship as elucidated from morphology studies by atomic force microscopy, transmission electron microscopy and X-ray ...

  15. Molecular dynamics as a method to gain understanding in questions concerning montmorillonite

    International Nuclear Information System (INIS)

    Seppaelae, A.; Vaari, J.; Puhakka, E.; Tanhua-Tyrkkoe, M.; Olin, M.; Kasa, S.

    2012-01-01

    Document available in extended abstract form only. Bentonite is one of the main material components to be used in the KBS-3 concept for safe disposal of spent nuclear fuel. The functional material in bentonite giving its beneficial properties is montmorillonite mineral. Montmorillonite consists of two completely different components: one nano-metre thick and approximately 200-400 nano-metres wide mineral layers carrying constant charge and charge compensating cations very near the mineral surfaces. The first component is more of a passive component while the second can absorb water molecules and change the cationic composition. In addition to montmorillonite bentonite usually contains some salts dissolved into water and accessory minerals. Any bulk bentonite is formed from these components via many scales of which structure is not yet fully known to science. Therefore the beneficial macroscopic properties of bentonite are assumed to follow from the nano-level structure and reactions. In safety studies of spent fuel disposal the time span to be considered extends beyond a hundred thousand years making any straightforward experimenting impossible. However, by modelling it is possible to study even very long periods of time. Unfortunately the model data and reactions are at least implicitly based on our short term experiments and may therefore be biased in some way. One possible solution to this may be the application of molecular chemistry or dynamics to construct the basis for our modelling studies. We have applied molecular chemistry on surface properties of kaolinite clay and biotite mineral but molecular dynamics is a new type of modelling for us. We believe that (during the coming ten years) molecular dynamics could make it easier to understand for example the following topics: How do charge compensating (exchanged) and aqueous cations interact? Why does water expand montmorillonite during wetting? Exact mechanism? How does water leave montmorillonite during

  16. Molecular dynamics simulations of the three-layer hydrate of Na-montmorillonite

    International Nuclear Information System (INIS)

    Holmboe, Michael; Bourg, Ian C.

    2012-01-01

    Document available in extended abstract form only. In many nuclear waste repositories concepts, compacted and smectite-rich bentonite clay is considered as an engineered transport barrier surrounding the canisters holding the nuclear waste. One of the requirements in the safety assessment of these repositories is to predict the transport rate of radionuclides as well as the overall hydraulic conductivity through the bentonite barrier. Kozaki and co-workers have obtained important information from diffusion experiments in bentonite on the mechanisms that control solute transport by studying the temperature-dependence of apparent diffusivity for solutes such as Na + , Cs + and Sr 2+ . Their results showed that the apparent diffusivity follows an Arrhenius relation (ln D a ∝ -E A /RT) with distinct activation energies of diffusion (E A ) for certain montmorillonite compactions, ionic strengths, and types of interlayer cation (Na + vs. Ca 2+ ). Their results suggest that solutes follow different diffusion pathways in compacted montmorillonite at different experimental conditions. In order to identify these transport pathways in compacted montmorillonite one needs independent knowledge of the relative abundance of the different types of interlayer nano-pores, i.e. the different coexisting hydration states (1W-3W), and of the molecular-scale EA for solute diffusion on the external basal surfaces of montmorillonite particles and in the interlayer nano-pores. The latter property can be obtained using molecular dynamics (MD) simulations, an important tool in the characterization of clays and clay minerals that yields detailed atomistic insights into the structural, dynamical and thermodynamic properties of many different geochemically relevant systems. In particular, MD simulations yield insight into the behavior of individual atoms, where most experimental methods only would probe the average behavior of large numbers of atoms or molecules. Thus, by simulating systems of

  17. Flocculation - Formation and structure of aggregates composed of polyelectrolyte chains and clay colloidal particles

    OpenAIRE

    Sakhawoth , Yasine

    2017-01-01

    Flocculation is a key process in numerous environmental and industrial technologies such as purification of waste-water or paper making. It is necessary to understand the formation and structure of the aggregates to control and optimize such a process. Most of the studies on flocculation involve spherical particles, but there is a clear need to understand the flocculation of anisotropic particles such as clay colloids, which are platelets. I studied the flocculation of montmorillonite clay su...

  18. Thermal stability and hot-stage Raman spectroscopic study of Ca-montmorillonite modified with different surfactants: A comparative study

    International Nuclear Information System (INIS)

    Sun, Zhiming; Park, Yuri; Zheng, Shuilin; Ayoko, Godwin A.; Frost, Ray L.

    2013-01-01

    Highlights: • A typical Ca-montmorillonite was modified with three surfactants through ion exchange. • The organoclays were characterized by XRD, TG and hot stage Raman. • The structural geometry and thermal properties of organoclays were analyzed. • The prepared organoclays show potential prospects in the environmental remediation. - Abstract: Three long chain cationic surfactants were intercalated into Ca-montmorillonite through ion exchange and the obtained organoclays were characterized by X-ray diffraction (XRD), high resolution thermogravimetric analysis (TG) and Raman spectroscopy. The intercalation of surfactants not only changes the surface properties of clay from hydrophilic to hydrophobic but also greatly increases the basal spacing of the interlayers based on XRD analysis. The thermal stability of organoclays intercalated with three surfactants (TTAB, DTAB and CTAB) and the different arrangements of the surfactant molecules intercalated into Ca-montmorillonite were determined by TG-DTG analysis. A Raman spectroscopic study on the Ca-montmorillonite modified by three surfactants prepared at different concentrations provided the detailed conformational ordering of different intercalated long-chain surfactants under different conditions. The wavenumber of the antisymmetric stretching mode is more sensitive than that of the symmetric stretching mode to the mobility of the tail of the amine chain. At room temperature, the conformational ordering is more easily affected by the packing density in the lateral model. With the increase of the temperature, the positions of both the antisymmetric and symmetric stretching bands shift to higher wavenumbers, which indicates a decrease of conformational ordering. This study offers new insights into the structure and properties of Ca-montmorillonite modified with different long chain surfactants. Moreover, the experimental results confirm the potential applications of organic Ca-montmorillonites for the removal

  19. Moessbauer and XRD Comparative Study of Host Rock and Iron Rich Mineral Samples from Paz del Rio Iron Ore Mineral Mine in Colombia

    International Nuclear Information System (INIS)

    Fajardo, M.; Perez Alcazar, G. A.; Moreira, A. M.; Speziali, N. L.

    2004-01-01

    A comparative study between the host rock and the iron rich mineral samples from the Paz del Rio iron ore mineral mine in Colombia was performed using X-ray diffraction and Moessbauer spectroscopy. Diffraction results of the iron rich mineral sample show that goethite, hematite, quartz, kaolinite and siderite are the main phases, and that a small amount of illite is also present. By Moessbauer spectroscopy at room temperature (RT) the presence of all the above mentioned phases was detected except quartz as well as an additional presence of small amount of biotite. The goethite, which appears as four sextets with hyperfine fields of 33.5, 30.5, 27.5 and 18.5 T, respectively, is the majority phase. This result shows the different grades of formation of this oxyhydroxide. The Moessbauer spectrum of this sample at 80 K presents the same phases obtained at RT without any superparamagnetic effect. In this case the goethite appears as two sextets. Diffraction results of the host rock sample show a large amount of quartz and kaolinite and small amounts of illite and biotite, whereas by Moessbauer spectroscopy illite, kaolinite and biotite were detected.

  20. Digestion of Alumina from Non-Magnetic Material Obtained from Magnetic Separation of Reduced Iron-Rich Diasporic Bauxite with Sodium Salts

    Directory of Open Access Journals (Sweden)

    Guanghui Li

    2016-11-01

    Full Text Available Recovery of iron from iron-rich diasporic bauxite ore via reductive roasting followed by magnetic separation has been explored recently. However, the efficiency of alumina extraction in the non-magnetic materials is absent. In this paper, a further study on the digestion of alumina by the Bayer process from non-magnetic material obtained after magnetic separation of reduced iron-rich diasporic bauxite with sodium salts was investigated. The results indicate that the addition of sodium salts can destroy the original occurrences of iron-, aluminum- and silicon-containing minerals of bauxite ore during reductive roasting. Meanwhile, the reactions of sodium salts with complex aluminum- and silicon-bearing phases generate diaoyudaoite and sodium aluminosilicate. The separation of iron via reductive roasting of bauxite ore with sodium salts followed by magnetic separation improves alumina digestion in the Bayer process. When the alumina-bearing material in bauxite ore is converted into non-magnetic material, the digestion temperature decreases significantly from 280 °C to 240 °C with a nearly 99% relative digestion ratio of alumina.

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

    Directory of Open Access Journals (Sweden)

    Ray L. Frost

    2012-10-01

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

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

    Digital Repository Service at National Institute of Oceanography (India)

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

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

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

    Science.gov (United States)

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

    2014-04-30

    Sorption efficiencies of modified montmorillonite and vermiculite of their mono ionic Na and organic HDTMA and HDP forms were studied against chemical and biological warfare agents such as yperite and selected bacterial strains. Yperite interactions with modified clay minerals were observed through its capture in low-density polyethylene foil-modified clay composites by measuring yperite gas permeation with using chemical indication and gas chromatography methods. The antibacterial activities of synthetized organoclays were tested against selected Gram-positive and Gram-negative bacterial species in minimum inhibitory concentration tests. The obtained results showed a positive influence of modified clay minerals on the significant yperite breakthrough-time increase. The most effective material was the polyethylene-Na form montmorillonite, while the polyethylene-Na form vermiculite showed the lowest efficiency. With increasing organic cations loading in the interlayer space the montmorillonite efficiency decreased, and in the case of vermiculite an opposite effect was observed. Generally the modified montmorillonites were more effective than modified vermiculites. The HDP cations seem to be more effective compare to the HDTMA. The antibacterial activity tests confirmed efficiency of all organically modified clay minerals against Gram-positive bacteria. The confirmation of antibacterial activity against Y. pestis, plague bacteria, is the most interesting result of this part of the study. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. 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...

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

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.

    Clay mineral distribution in the sediments of the west coast of India indicates that the illite and chlorite-rich sediments, derived from the Indus, occupy the continental shelf of the northern part of the Gulf of Kutch. Montmorillonite derived from...

  6. Gallium sorption on montmorillonite and illite colloids: Experimental study and modelling by ionic exchange and surface complexation

    International Nuclear Information System (INIS)

    Benedicto, Ana; Degueldre, Claude; Missana, Tiziana

    2014-01-01

    Highlights: • Ga sorption onto illite and montmorillonite was studied and modelled for the first time. • The developed sorption model was able to well explain Ga sorption in both clays. • Number of free parameters was reduced applying the linear free energy relationship. • Cationic exchange dominate sorption at pH < 4.5; surface complexation at higher pH. - Abstract: The migration of metals as gallium (Ga) in the environment is highly influenced by their sorption on clay minerals, as montmorillonite and illite. Given the increased usage of gallium in the industry and the medicine, the Ga-associated waste may result in environmental problems. Ga sorption experiments were carried out on montmorillonite and illite colloids in a wide range of pH, ionic strength and Ga concentration. A Ga sorption model was developed combining ionic exchange and surface complexation on the edge sites (silanol and aluminol-like) of the clay sheets. The complexation constants were estimated as far as possible from the Ga hydrolysis constants applying the linear free energy relationship (LFER), which allowed to reduce the number of free parameters in the model. The Ga sorption behaviour was very similar on illite and montmorillonite: decreasing tendency with pH and dependency on ionic strength at very acidic conditions. The experimental data modelling suggests that the Ga sorption reactions avoid the Ga precipitation, which is predicted in absence of clay colloids between pH 3.5 and 5.5. Assuming this hypothesis, clay colloids would affect Ga aqueous speciation, preventing precipitation in favour of sorption. Ga sorption on montmorillonite and illite can be explained on the basis of three main reactions: Ga 3+ exchange at very acidic conditions (pH < ∼3.8); Ga(OH) 4 - complexation on protonated weak sites in acidic-neutral conditions (between pH ∼5.2 and pH ∼7.9); and Ga(OH) 3 complexation on strong sites at basic conditions (pH > ∼7.9)

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

    Science.gov (United States)

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

    2015-12-28

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

  8. Polyaniline nanocomposites via in situ emulsion polymerization based on montmorillonite: Preparation and characterization

    Directory of Open Access Journals (Sweden)

    M.A. Abd El-Ghaffar

    2015-11-01

    Full Text Available Polyaniline nanocomposites were prepared via in situ emulsion polymerization in the presence of Na+ montmorillonite (Na+MMT. For achieving this purpose the clay was organophilized to (MMT-CTA form using cetyltrimethyl ammonium bromide (CTAB. The X-ray diffraction (XRD demonstrated that the basal space of Na+-montmorillonite increased after the organophilization from 11.21 to 19.35 Å. Polyaniline/montmorillonite (PAn/MMT nanocomposites were prepared by intercalating the emulsion of aniline monomer with treated organically layers of (Na+-MMT using ammonium peroxydisulfate (APS as an initiator. Furthermore aniline hydrochloride (AnHCl was used as a modifier and monomer to prepare PAn/H+MMT nanocomposites by cation exchange of the anilinuim moiety with the sodium ion inside the basal spaces which enlarged after the polymerization process to 35 Å as evidenced from X-ray diffraction (XRD. The d-spacing of the PAn/H+-MMT nanocomposite was found to become wider about 23.79 Å than that of the pure Na+-MMT, and successful intercalation or exfoliation of PAnH+ into Na+-MMT layers. The prepared PAn/MMT nanocomposites were characterized by thermal gravimetric analysis (TGA, scanning electron microscope (SEM, and transmission electron microscope (TEM. The electrical property measurements showed an enhancement in the conductivity values of the prepared nanocomposites especially on using AnHCl monomer to be in the order of 10−1 S/cm.

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

    Directory of Open Access Journals (Sweden)

    Hideo Hashizume

    2015-02-01

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

  10. Transport of oxidants and radionuclides through a clay barrier

    International Nuclear Information System (INIS)

    Neretnieks, I.

    1978-02-01

    The masstransfer rate for oxidants to, and radionuclides from a capsule in a repository has been computed. The capsule which is 0.75 m in diameter is surrounded by Montmorillonite clay. The hole is 1.5 m in diameter. For one capsule about 1220g copper will corrode due to oxygen corrosion in 10 000 years. If the fissures in the rock nearest the hole are filled with clay, the corrosion will decrease significantly. This is valid for a case where the groundwater is in equilibrium with oxygen of 0.2 bar pressure (normal air pressure). Measurements of the oxygen content in groundwater at large depths show a more than 1 000 times smaller values. The transport rate will then be correspondingly smaller. Corrosion due to sulphate/sulphide corrosion may reach some 590 g in the same time if there is 10 mg/l of the least abundant component. The radionuclides Sr 90 , Cs 137 , Am 241 and Am 243 will decay totally in the clay barriers. Pu 240 will be seriously hindered. The total dissolution of the uranium oxide in a capsule takes at least 1.8 million years. Nuclides with high solubilities decrease in about 2 000 years to half their original concentration. The sodium in the Montmorillonite clay in the fissures is exchanged for calcium in about 20 000 years. The exchange of the sodium in the clay in the hole takes millions of years

  11. Influence of Laurolactam Content on the Clay Intercalation of Polyamide 6,12/Clay Nanocomposites Synthesized by Open Ring Anionic Polymerization

    Directory of Open Access Journals (Sweden)

    E. N. Cabrera Álvarez

    2012-01-01

    Full Text Available In situ anionic homo- and copolymerization of caprolactam (CL and laurolactam (LL with sodium montmorillonite clay (NaMMT was carried out using two different initiators, sodium caprolactamate (CLNa and caprolactam magnesium bromide (CLMgBr. Degree of conversion and final molecular weight were used to assess the advancement and efficiency of the polymerization reaction and X-ray diffraction and electron microscopy were used to evaluate the sodium montmorillonite clay intercalation/exfoliation. The use of CLNa as initiator produced a higher conversion degree and molecular weight than the use of CLMgBr. Through DSC, it was observed that CLNa and CLMgBr tended to produce random and block copolymer structures, respectively, and either random or block, this eventually has an effect on the clay dispersion within the polymer matrix. In all cases, increasing the LL content produced a decrease in the conversion degree and in the molecular weight of the resulting polymer.

  12. Ice nucleation of ammonia gas exposed montmorillonite mineral dust particles

    Directory of Open Access Journals (Sweden)

    A. Salam

    2007-07-01

    Full Text Available The ice nucleation characteristics of montmorillonite mineral dust aerosols with and without exposure to ammonia gas were measured at different atmospheric temperatures and relative humidities with a continuous flow diffusion chamber. The montmorillonite particles were exposed to pure (100% and diluted ammonia gas (25 ppm at room temperature in a stainless steel chamber. There was no significant change in the mineral dust particle size distribution due to the ammonia gas exposure. 100% pure ammonia gas exposure enhanced the ice nucleating fraction of montmorillonite mineral dust particles 3 to 8 times at 90% relative humidity with respect to water (RHw and 5 to 8 times at 100% RHw for 120 min exposure time compared to unexposed montmorillonite within our experimental conditions. The percentages of active ice nuclei were 2 to 8 times higher at 90% RHw and 2 to 7 times higher at 100% RHw in 25 ppm ammonia exposed montmorillonite compared to unexposed montmorillonite. All montmorillonite particles are more efficient as ice nuclei with increasing relative humidities and decreasing temperatures. The activation temperature of montmorillonite exposed to 100% pure ammonia was 15°C higher than for unexposed montmorillonite particles at 90% RHw. In the 25 ppm ammonia exposed montmorillonite experiments, the activation temperature was 10°C warmer than unexposed montmorillonite at 90% RHw. Degassing does not reverse the ice nucleating ability of ammonia exposed montmorillonite mineral dust particles suggesting that the ammonia is chemically bound to the montmorillonite particle. This is the first experimental evidence that ammonia gas exposed montmorillonite mineral dust particles can enhance its activation as ice nuclei and that the activation can occur at temperatures warmer than –10°C where natural atmospheric ice nuclei are very scarce.

  13. Adsorption of ferrous ions onto montmorillonites

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Dawei, E-mail: qdw109@163.com [Qilu University of Technology, Jinan, 250353, Shandong (China); Niu, Xia [Qilu University of Technology, Jinan, 250353, Shandong (China); Qiao, Min; Liu, Gang; Li, Hongxin; Meng, Zhenxiao [Shandong SiBang pharmaceutical co., LTD, Jinan, Shandong, 250200 (China)

    2015-04-01

    Highlights: • Adsorption study of ferrous ions on montmorillonites. • Using ascorbic acid as antioxidants in adsorption process. • Fe (II)-MMT had good affinity for phosphate. - Abstract: The adsorption of Fe (II) onto montmorillonites was investigated through initial concentration, contact time, pH and temperature. During the whole adsorption process, the ascorbic acid (Vitamin C) was added as a kind of antioxidant, at the same time, deionized water (after boiling) and nitrogen protection were also used to avoid oxidation. The Fe{sup 2+}/Fe{sub total} ratio of the iron exists in the Fe-montmorillonites was found more than 95%. Two kinetic models, including pseudo-first-order and pseudo-second-order model, were used to analyze the adsorption process of Fe (II) on montmorillonites. The results of our study showed that adsorption process fitted with pseudo-second-order well. Adsorption isotherms showed that Langmuir model was better than Freundlich model. The thermodynamic parameters ΔG{sup 0} and ΔH{sup 0} were 3.696 kJ/mol and 6.689 kJ/mol (we just gave the values at 298 K), respectively. The positive values at different temperatures showed that the adsorption process was non-spontaneous and endothermic. The characteristics of materials were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Surface area and porosity analyzer, Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC) and Zeta potential distribution.

  14. A new luminescent montmorillonite/borane nanocomposite

    Czech Academy of Sciences Publication Activity Database

    Kolská, Z.; Matoušek, J.; Čapková, P.; Braborec, Jakub; Benkocká, M.; Černá, H.; Londesborough, Michael Geoffrey Stephen

    2015-01-01

    Roč. 118, DEC (2015), s. 295-300 ISSN 0169-1317 Institutional support: RVO:61388980 Keywords : Luminophore * Montmorillonite/borane nanocomposite * X-ray photoelectron spectroscopy * X-ray diffraction * UV–Vis spectra Subject RIV: CA - Inorganic Chemistry Impact factor: 2.586, year: 2015

  15. Comparing uranyl sorption complexes on soil and reference clays

    International Nuclear Information System (INIS)

    Chisholm-Brause, C.J.; Berg, J.M.; Conradson, S.D.; Morris, D.E.; McKinley, J.P.; Zachara, J.M.

    1993-01-01

    Clay minerals and other components in natural soils may play a key role in limiting the mobility of uranium in the environment through the formation of sorption complexes. Reference clays are frequently used as models to study sorption processes because they have well-known chemical and physical properties, but they may differ chemically and morphologically from clays derived from natural soils. Therefore, inferences based on reference clay data have been questioned. The authors have used luminescence and x-ray absorption spectroscopies to characterize the sorption complexes of aqueous uranyl (UO 2 2+ ) species on two soil smectites from the Kenoma and Ringold formations, and compared these results to those obtained on reference smectite clays. The pH dependence of uptake suggests that the ratio of sorption on amphoteric edge sites is greater for the soil smectites than for reference clays such as Wyoming montmorillonite (SWy-1). The luminescence spectra for uranyl sorbed to the soil clays are very similar to those for uranyl sorbed principally to the edge sites of SWy-1. This observation supports the solution data suggesting that adsorption to amphoteric sites is a more important mechanism for soil clays. However, the spectral data indicate that the sorption complexes on natural and reference clays are quite similar. Furthermore, as with the reference clays, the authors have found that the chemistry of the solution plays a greater role in defining the sorption complex than does the clay matrix. Thus, if differences in surface properties are adequately taken into account, the reference clays may serve as useful analogs for soil clays in investigations of metal-ion sorption

  16. Neutron Time-of-Flight Quantification of Water Desorption Isotherms of Montmorillonite

    DEFF Research Database (Denmark)

    Gates, Will P.; Bordallo, Heloisa N.; Aldridge, Laurence P.

    2012-01-01

    enabled us to differentiate at least two water motions during dehydration of Ca- and Na-SAz-1 (initially equilibrated at RH = 55%) by using a "controlled water loss" time-of-flight procedure. This work confirms that (a) interlayer and cationic water in dioctahedral smectites are characterized by slower...... motions than interparticle water, (b) interlayer cations influenced the dynamics of water loss, probably through its affect on clay fabric, and (c) interparticle water behaves more like bulk water. At 55% RH the Ca montmorillonite held more interparticle water, but on dehydration under controlled......The multiple energy states of water held by surfaces of a clay mineral can be effectively probed with time-of-flight and fixed elastic window neutron scattering. We used these techniques to quantitatively differentiate water types, including rotational and translational diffusions, in Ca- and Na...

  17. One-step synthesis and structural features of CdS/montmorillonite nanocomposites.

    Science.gov (United States)

    Han, Zhaohui; Zhu, Huaiyong; Bulcock, Shaun R; Ringer, Simon P

    2005-02-24

    A novel synthesis method was introduced for the nanocomposites of cadmium sulfide and montmorillonite. This method features the combination of an ion exchange process and an in situ hydrothermal decomposition process of a complex precursor, which is simple in contrast to the conventional synthesis methods that comprise two separate steps for similar nanocomposite materials. Cadmium sulfide species in the composites exist in the forms of pillars and nanoparticles, the crystallized sulfide particles are in the hexagonal phase, and the sizes change when the amount of the complex for the synthesis is varied. Structural features of the nanocomposites are similar to those of the clay host but changed because of the introduction of the sulfide into the clay.

  18. Preparation and characterization of new polyamide/montmorillonite nanocomposites containing azo moiety in the main chain

    Directory of Open Access Journals (Sweden)

    Khalil Faghihi

    2016-11-01

    Full Text Available Two new samples of polyamide/montmorillonite reinforced nanocomposites containing 4,4′-azobenzoic acid moiety in the main chain were synthesized by a convenient solution intercalation technique. Polyamide (PA 4 as a source of polymer matrix was synthesized by the direct polycondensation reaction of 4,4′-azobenzoic acid 2 with 4,4′-diamino diphenyl ether 3 in the presence of triphenyl phosphite (TPP, CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP. Morphology and structure of the resulting PA-nanocomposite films 4a and 4b with 10 and 20% silicate particles were characterized by FTIR spectroscopy, X-ray diffraction (XRD and scanning electron microscopy (SEM. The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nanocomposites films were investigated by using UV–vis spectroscopy, thermogravimetric analysis (TGA and water uptake measurements.

  19. Adsorption of barium on kaolinite, illite and montmorillonite at various ionic strengths

    International Nuclear Information System (INIS)

    Atun, G.; Bascetin, E.

    2003-01-01

    The sorption behaviour of Ba 2+ in three different clay minerals from various regions of Turkey has been investigated by means of a tracer technique using 133 Ba in batch experiments. Sorption of Ba 2+ on montmorillonite, kaolinite and illite has been studied in mixed solutions of BaCl 2 and NaCl at ionic strengths ranging from 1 x 10 -3 M to 1 x 10 -1 M. The L-shape exchange isotherms for Ba 2+ -Na + systems are well defined by a Langmuir type equation. The exchange capacity of Ba 2+ ions for all three clay minerals increased with decreasing ionic strength. The adsorption data were fitted to a Freundlich isotherm and empirical Freundlich parameters enabled to the generation of a site distribution function. The selectivity coefficients were nearly constant at low Ba loading and decreased as loading increased. This behavior was an indication of an ion exchange process between Ba 2+ and Na + ions

  20. Transparent films based on PLA and montmorillonite with tunable oxygen barrier properties

    DEFF Research Database (Denmark)

    Svagan, Anna; Åkesson, Anna; Cárdenas, Marité

    2012-01-01

    Polylactide (PLA) is viewed as a potential material to replace synthetic plastics (e.g., poly(ethylene terephthalate) (PET)) in food packaging, and there have been a number of developments in this direction. However, for PLA to be competitive in more demanding uses such as the packaging of oxygen......-sensitive foods, the oxygen permeability coefficient (OP) needs to be reduced by a factor of ∼10. To achieve this, a layer-by-layer (Lbl) approach was used to assemble alternating layers of montmorillonite clay and chitosan on extruded PLA film surfaces. When 70 bilayers were applied, the OP was reduced by 99...... and 96%, respectively, at 20 and 50% RH. These are, to our knowledge, the best improvements in oxygen barrier properties ever reported for a PLA/clay-based film. The process of assembling such multilayer structures was characterized using a quartz crystal microbalance with dissipation monitoring...

  1. Aggregation of montmorillonite and organic matter in aqueous media containing artificial seawater

    Directory of Open Access Journals (Sweden)

    Kim Jinwook

    2009-01-01

    Full Text Available Abstract Background The dispersion-aggregation behaviors of suspended colloids in rivers and estuaries are affected by the compositions of suspended materials (i.e., clay minerals vs. organic macromolecules and salinity. Laboratory experiments were conducted to investigate the dispersion and aggregation mechanisms of suspended particles under simulated river and estuarine conditions. The average hydrodynamic diameters of suspended particles (representing degree of aggregation and zeta potential (representing the electrokinetic properties of suspended colloids and aggregates were determined for systems containing suspended montmorillonite, humic acid, and/or chitin at the circumneutral pH over a range of salinity (0 – 7.2 psu. Results The montmorillonite-only system increased the degree of aggregation with salinity increase, as would be expected for suspended colloids whose dispersion-aggregation behavior is largely controlled by the surface electrostatic properties and van der Waals forces. When montmorillonite is combined with humic acid or chitin, the aggregation of montmorillonite was effectively inhibited. The surface interaction energy model calculations reveal that the steric repulsion, rather than the increase in electronegativity, is the primary cause for the inhibition of aggregation by the addition of humic acid or chitin. Conclusion These results help explain the range of dispersion-aggregation behaviors observed in natural river and estuarine systems. It is postulated that the composition of suspended particles, specifically the availability of steric polymers such as those contained in humic acid, determine whether the river suspension is rapidly aggregated and settled or remains dispersed in suspension when it encounters increasingly saline environments of estuaries and oceans.

  2. Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Pingxiao, E-mail: pppxwu@scut.edu.cn [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Li, Shuzhen [School of Chemical and Environmental Engineering, Wuyi University, Jiangmen, Guangdong Province 529020 (China); Ju, Liting [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Zhu, Nengwu [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006 (China); The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions (China); Wu, Jinhua; Li, Ping [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Dang, Zhi [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006 (China); The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions (China)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Organo-montmorillonite supported iron nanoparticles were found to be more efficient in the removal of Cr(VI) than unsupported iron nanoparticles. Black-Right-Pointing-Pointer The iron nanoparticles were accommodated by the sectional structure of the clay minerals which were helpful to protect the nanoparticles from aggregating. Black-Right-Pointing-Pointer XPS and XANES provided some direct information about the reduction mechanisms. Black-Right-Pointing-Pointer The structure of the supported iron nanoparticles was stable in the reaction with Cr(VI). - Abstract: Iron nanoparticles exhibit greater reactivity than micro-sized Fe{sup 0}, and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe{sup 0} was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III).

  3. Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles

    International Nuclear Information System (INIS)

    Wu, Pingxiao; Li, Shuzhen; Ju, Liting; Zhu, Nengwu; Wu, Jinhua; Li, Ping; Dang, Zhi

    2012-01-01

    Highlights: ► Organo-montmorillonite supported iron nanoparticles were found to be more efficient in the removal of Cr(VI) than unsupported iron nanoparticles. ► The iron nanoparticles were accommodated by the sectional structure of the clay minerals which were helpful to protect the nanoparticles from aggregating. ► XPS and XANES provided some direct information about the reduction mechanisms. ► The structure of the supported iron nanoparticles was stable in the reaction with Cr(VI). - Abstract: Iron nanoparticles exhibit greater reactivity than micro-sized Fe 0 , and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe 0 was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III).

  4. Functional properties of extruded nano composites based on cassava starch, polyvinyl alcohol and montmorillonite; Propriedades funcionais de nanocompositos extrusados de amido de mandioca, alcool polivinilico e montmorilonita

    Energy Technology Data Exchange (ETDEWEB)

    Debiagi, Flavia; Mali, Suzana [Departamento de Bioquimica e Biotecnologia, Universidade Estadual de Londrina, PR (Brazil)

    2011-07-01

    The objectives of this work were to produce expanded nano composites (foams) based on starch, PVA and sodium montmorillonite and characterize them according to their expansion index (EI), density, water absorption capacity (WSC), mechanical properties and X-ray diffraction. The nano composites were prepared in a single-screw extruder using different starch contents (97.6 - 55.2 g/100 g formulation), PVA (0 - 40 g/100 g formulation), unmodified nano clay - Closite - Na (0 - 4. 8 g/100 g formulation) and glycerol (20 g/100 g formulation) as plasticizer. The addition of montmorillonite and PVA resulted in an increase of EI and a decrease of density of the samples, and reduced WSC and increased the mechanical strength of the foams. Through the analysis of X-ray diffraction can be observed that the addition of montmorillonite led to production of intercalated nano composites in all samples. (author)

  5. Clay catalyzed RNA synthesis under Martian conditions: Application for Mars return samples.

    Science.gov (United States)

    Joshi, Prakash C; Dubey, Krishna; Aldersley, Michael F; Sausville, Meaghen

    2015-06-26

    Catalysis by montmorillonites clay minerals is regarded as a feasible mechanism for the abiotic production and polymerization of key biomolecules on early Earth. We have investigated a montmorillonite-catalyzed reaction of the 5'-phosphorimidazolide of nucleosides as a model to probe prebiotic synthesis of RNA-type oligomers. Here we show that this model is specific for the generation of RNA oligomers despite deoxy-mononucleotides adsorbing equally well onto the montmorillonite catalytic surfaces. Optimum catalytic activity was observed over a range of pH (6-9) and salinity (1 ± 0.2 M NaCl). When the weathering steps of early Earth that generated catalytic montmorillonite were modified to meet Martian soil conditions, the catalytic activity remained intact without altering the surface layer charge. Additionally, the formation of oligomers up to tetramer was detected using as little as 0.1 mg of Na⁺-montmorillonite, suggesting that the catalytic activity of a Martian clay return sample can be investigated with sub-milligram scale samples. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Nanoporous polymer--clay hybrid membranes for gas separation.

    Science.gov (United States)

    Defontaine, Guillaume; Barichard, Anne; Letaief, Sadok; Feng, Chaoyang; Matsuura, Takeshi; Detellier, Christian

    2010-03-15

    Nanohybrid organo-inorgano clay mineral-polydimethylsiloxane (PDMS) membranes were prepared by the reaction of pure and/or modified natural clay minerals (Sepiolite and montmorillonite) with PDMS in hexane, followed by evaporation of the solvent at 70 degrees C. The membranes were characterized by means of XRD, SEM, ATD-TG and solid state (29)Si magic angle spinning (MAS) and cross-polarization (CP) CP/MAS NMR. The morphology of the membranes depends on the content loading of clay mineral. For low content, the membrane composition is homogeneous, with well dispersed nanoparticles of clay into the polymer matrix, whereas for higher clay content, the membranes are constituted also of a mixture of well dispersed nanoparticles into the polymer, but in the presence of agglomerations of small clay particles. Quantitative (29)Si MAS NMR demonstrated a strong correlation between the clay content of the membrane and the average length of the PDMS chain, indicating that the nanohybrid material is made of clay particles covalently linked to the PDMS structure. This is particularly the case for Sepiolite with has a high density of Q(2) silanol sites. The separation performances of the prepared membranes were tested for CO(2)/CH(4) and O(2)/N(2) mixtures. The observed separation factors showed an increase of the selectivity in the case of CO(2)/CH(4) in comparison with membranes made from PDMS alone under the same conditions. 2009 Elsevier Inc. All rights reserved.

  7. Adsorption of Benzene by “Green” functionalization of Montmorillonite

    Directory of Open Access Journals (Sweden)

    Anjum Hirra

    2018-01-01

    Full Text Available The capacity of organically modified Montmorillonite (MMT clay to adsorb nonpolar organic compound (benzene in an aqueous solution, was investigated under the batch process. MMT was pretreated (centrifuged and then functionalized with green intercalating agent i.e. 1-hexyl-3-methyl imadazolium chloride [HMim][Cl]. The characterization through Fourir Transoform Infrared Spectroscopy (FTIR, Differential Scanning Calorimeter (DSC and Field Emission Scanning Electron Microscope (FE-SEM confirmed the presence of the oxygen containing functional groups, changes in melting point and variation in the morphological properties. The governing parameters for the sorption of benzene such as the effect of contact time, pH, adsorbent dose and rotation were studied. The kinetic data conformed to pseuodo 2nd order kinetic model and the isotherm experimental data were a better fit to Langmuir model with maximum adsorption capacity of 588.23mg/g under experimental conditions. Overall, MMT intercalated with 1-hexyl-3-methyl imadazolium chloride is a promising environmental friendly adsorbent for the abatement of benzene in an aqueous solution.

  8. Sorption of cesium on montmorillonite and effect of salt concentration

    International Nuclear Information System (INIS)

    Atun, G.; Bilgin, B.; Mardinli, A.

    1996-01-01

    The sorption behavior of cesium on montmorillonite type[e clay was studied by using radioactivity measurements. Concentrations of Cs + ions ranged from 10 -6 to 10 -2 M. Cesium retention reduced with increasing salt concentration which was varied between 10 -4 and 10 -1 M. Selectivity coefficients K CsNa for the exchange between Cs and Na were calculated for different equivalent fractions of Cs on the solid phase. Using the K CsNa values, free energy change was found to be 7.8 kJ/mol. The data could be fitted to a Freundlich isotherm, and empirical Freundlich parameters enabled the generation of a site distribution function. By fitting the data to the Dubinin-Radushkevich (D-R) isotherm, a mean energy of sorption of 8.6kJ/mole was calculated which corresponds to the energy of ion exchange reactions. The values of energy changes calculated by using two different methods were in good agreement. (author)

  9. Iron and cell death in Parkinson's disease: a nuclear microscopic study into iron-rich granules in the parkinsonian substantia nigra of primate models

    Energy Technology Data Exchange (ETDEWEB)

    Thong, P.S.P.; Watt, F. E-mail: phywattf@nus.edu.sg; Ponraj, D.; Leong, S.K.; He, Y.; Lee, T.K.Y

    1999-09-02

    Parkinson's disease is a degenerative brain disease characterised by a loss of cells in the substantia nigra (SN) region of the brain and accompanying biochemical changes such as inhibition of mitochondrial function, increased iron concentrations and decreased glutathione levels in the parkinsonian SN. Though the aetiology of the disease is still unknown, the observed biochemical changes point to the involvement of oxidative stress. In particular, iron is suspected to play a role by promoting free radical production, leading to oxidative stress and cell death. The increase in iron in the parkinsonian SN has been confirmed by several research groups, both in human post-mortem brains and in brain tissue from parkinsonian animal models. However, the question remains as to whether the observed increase in iron is a cause or a consequence of the SN cell death process. Our previous study using unilaterally 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP)-lesioned monkeys in a time sequence experiment has shown that the increase in bulk iron concentrations follow rather than precede dopaminergic cell death. However, changes in the localised iron concentrations, which may play a more direct role in SN cell death, may not be reflected at the bulk level. Indeed, we have observed iron-rich granules in parkinsonian SNs. From this time sequence study into the iron content of iron-rich granules in the SNs of an untreated control and unilaterally MPTP-lesioned parkinsonian models, we present the following observations: (1) Iron-rich granules are found in both control and parkinsonian SNs and are variable in size and iron content in any one model. (2) These iron-rich granules may be associated with neuromelanin granules found in the SN and are known to accumulate transition metal ions such as iron. (3) The early onset of bulk SN cell loss (35%) was accompanied by a significant elevation of iron in granules found in the MPTP-injected SN compared to the contra-lateral SN

  10. Nanocomposite PAAm/methyl cellulose/montmorillonite hydrogel: evidence of synergistic effects for the slow release of fertilizers.

    Science.gov (United States)

    Bortolin, Adriel; Aouada, Fauze A; Mattoso, Luiz H C; Ribeiro, Caue

    2013-08-07

    In this work, we synthesized a novel series of hydrogels composed of polyacrylamide (PAAm), methylcellulose (MC), and calcic montmorillonite (MMt) appropriate for the controlled release of fertilizers, where the components presented a synergistic effect, giving very high fertilizer loading in their structure. The synthesized hydrogel was characterized in relation to morphological, hydrophilic, spectroscopic, structural, thermal, and kinetic properties. After those characterizations, the application potential was verified through sorption and desorption studies of a nitrogenated fertilizer, urea (CO(NH2)2). The swelling degree results showed that the clay loading considerably reduces the water absorption capability; however, the hydrolysis process favored the urea adsorption in the hydrogel nanocomposites, increasing the load content according to the increase of the clay mass. The FTIR spectra indicated that there was incorporation of the clay with the polymeric matrix of the hydrogel and that incorporation increased the water absorption speed (indicated by the kinetic constant k). By an X-ray diffraction technique, good nanodispersion (intercalation) and exfoliation of the clay platelets in the hydrogel matrix were observed. Furthermore, the presence of the montmorillonite in the hydrogel caused the system to liberate the nutrient in a more controlled manner than that with the neat hydrogel in different pH ranges. In conclusion, excellent results were obtained for the controlled desorption of urea, highlighting the hydrolyzed hydrogels containing 50% calcic montmorillonite. This system presented the best desorption results, releasing larger amounts of nutrient and almost 200 times slower than pure urea, i.e., without hydrogel. The total values of nutrients present in the system show that this material is potentially viable for application in agriculture as a nutrient carrier vehicle.

  11. Removal of remazol yellow with modified clays with iron; Remocion de amarillo remazol con arcillas modificadas con hierro

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Gomez T, A. P.

    2012-07-01

    Clays have the ability to absorb water and to retain in its structure both hydrophilic and hydrophobic substances, therefore, it is possible to use them in the sorption of dyes from waste water, in order to avoid affecting water bodies or storm drains when they are discharged. In this paper the montmorillonite KSF and a sodium bentonite from the Morelos State, Mexico were studied for the sorption of an azo dye used in textiles knows as remazol yellow. These clays were modified with iron, the dye sorption behaviors and their regeneration processes for their reuse were determined. It was difficult to separate the sodium bentonite after being in contact with aqueous solutions; therefore it was nor a candidate dor the removal of remazol yellow from aqueous solutions. The montmorillonite KSF was characterized before and after the iron modification, and after its regeneration by scanning electron microscopy (elemental analysis), infrared spectrometry, X-ray diffraction, and the specific areas of the materials were determined by Bet analysis. The adsorption equilibrium time and the adsorption rate for remazol yellow were determined from the fitting of the experimental results to mathematical models for the unmodified and iron modified montmorillonite KSF. The adsorption capacity was determined from the adsorption isotherms and mathematical models. The influence of the ph in the sorption processes was determined as well, and it was found that, ph values between 2 and 12 do not have any influence on the adsorption processes for iron modified montmorillonite KSF. The montmorillonite KSF and the iron modified montmorillonite KSF are adequate adsorbents for the removal of remazol yellow from aqueous solutions. Although, the sorption capacity for the unmodified montmorillonite KSF is higher (about 10%) than the capacity for the iron modified montmorillonite KSF and the stability of the last one increased. The saturated clays with remazol yellow were treated with Fenton reactive

  12. Frictional strength of wet and dry montmorillonite

    Science.gov (United States)

    Morrow, C. A.; Moore, D. E.; Lockner, D. A.

    2017-05-01

    Montmorillonite is a common mineral in fault zones, and its low strength relative to other common gouge minerals is important in many models of fault rheology. However, the coefficient of friction, μ, varies with degree of saturation and is not well constrained in the literature due to the difficulty of establishing fully drained or fully dried states in the laboratory. We measured μ of both saturated and oven-dried montmorillonite at normal stresses up to 700 MPa. Care was taken to shear saturated samples slowly enough to avoid pore fluid overpressure. For saturated samples, μ increased from 0.10 to 0.28 with applied effective normal stress, while for dry samples μ decreased from 0.78 to 0.45. The steady state rate dependence of friction, (a - b), was positive, promoting stable sliding. The wide disparity in reported frictional strengths can be attributed to experimental procedures that promote differing degrees of partial saturation or overpressured pore fluid conditions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng [Sandia National Laboratories, Albuquerque, NM 87185 (United States)

    2012-07-01

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

  14. Bentonite clay purification for development of polymeric nan composites using a single screw extruder

    International Nuclear Information System (INIS)

    Carvalho, Ana C.M. de; Ito, Edson N.; Costa, Maria C.B.; Barbosa, Maria I.R.

    2011-01-01

    In this work, a bentonite clay rich in montmorillonite was purified and chemical treat to be used in the development of poly (methyl methacrylate) /clay nanocomposites via melting processes. After the clay treatment and purification, a masterbatch with 25% clay and 75% PMMA was produced by solution technique, using acetone as solvent. For produce samples with 2.5% clay, the masterbatch along with pure polymer were added and mixed in single screw extruder with a diameter of 16 mm and W/D 26. X-rays diffractometry (XRD) and X-rays fluorescence (XRF). Tests were performed to evaluate and characterizing the bentonite clay used in the development of this work and differential scanning calorimetry (DSC) tests were performed to evaluate changes in the thermal properties of the nanocomposites produced. (author)

  15. Use of the montmorillonite as crosslink agents for chitosan; Uso da montmorilonita como agente de reticulacao para a quitosana

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Rossemberg C.; Lima, Rosemary S. Cunha; Braga, Carla R. Costa [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Programa de Pos-graduacao em Ciencia e Engenharia de Materiais; Fook, Marcus V. Lia; Silva, Suedina M. Lima [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia de Materiais

    2009-07-01

    The montmorillonite (the main constituent of bentonite) has been the most commonly used inorganic load in the formation of nanocomposites chitosan / layered silicate. To evaluate its effect as an agent for the reticulation of chitosan, a sodium montmorillonite, Cloisite Na{sup +}, supplied by Southern Clay Products, Texas, USA, was used. For the reticulation of chitosan dispersions of chitosan / Cloisite Na{sup +} were prepared in different proportions and the obtained films characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TG). The results indicated that the Cloisite Na{sup +} was for efficient and the reticulation of the chitosan and can be used in place of sulfuric acid, which is one of the most common reticulants for chitosan. (author)

  16. In-vivo study of genotoxic and inflammatory effects of the organo-modified Montmorillonite Cloisite® 30B

    DEFF Research Database (Denmark)

    Sharma, Anoop Kumar; Mortensen, Alicja; Schmidt, Bjørn

    2014-01-01

    exposure to clay particles from Cloisite® 30B. Detection and identification of free quaternary ammonium modifier in the highest dose of Cloisite® 30B was carried out by high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF-MS). This analysis revealed...... a mixture of three quaternary ammonium analogues. The detected concentration of the organomodifier corresponded to an exposure of rats to about 5 mg quaternary ammonium analogues/kg body weight.......Because of the increasing use of clays and organoclays in industrial applications it is of importance to consider the toxicity of these materials. Recently it was reported that the commercially available Montmorillonite clay, Cloisite® 30B, which is surface-modified by organic quaternary ammonium...

  17. Flow-induced crystallization of a nano composite of poly(butylene adipate-co-terephthalate)/montmorillonite

    International Nuclear Information System (INIS)

    Bonel, Alan B.; Rego, Bruna T.; Beatrice, Cesar A.G.; Marini, Juliano; Bretas, Rosario E.S.

    2011-01-01

    Poly(butylene adipate-co-terephthalate) (PBAT) with 5wt% of an organically modified montmorillonite with polar surfactant was prepared by melt blending in a co-rotational twin-screw extruder at 160 degree C. 100rpm and 1 kg/h. Both pure polymer and nano composite were characterized by wide measurements. The study of the flow-induced crystallization was also done by rheological measurements, monitoring the viscosity as a function of time. The nano clay's lamellas were intercalated in the polymer m loss moduli of the nano composite, at low frequencies, showed that the particles of the nano clay were well dispersed and distributed thru the PBAT matrix. Finally, the presence of the nano clay's particles reduced the induction tim crystals growth, due to the strong interactions with the PBAT chains. (author)

  18. New approach to obtain elastomeric nano composites with clay from lattices

    International Nuclear Information System (INIS)

    Azeredo, Luciane K. de; Jacobi, Marly M.

    2009-01-01

    Rubber-Montmorillonite nanocomposites were prepared by Continuous Dynamic Latex Compounding (CDLC). This technique, recently developed in our laboratory, permits an intensive intercalation of the polymer at very small residence times in an elongational flow reactor. The processing conditions strongly affect the morphology of nanocomposites characterized by TEM and XRD. Clay-rubber nanocomposites were prepared from the mixture of NBR-, XNBR- and SBR-latex and aqueous suspensions of Na-montmorillonite. The polarity of rubbers influences the final properties of nanocomposites. The nanocomposites obtained by CDLC showed better reinforcement and permeation resistance at far less volume fractions than the obtained with carbon black or silica by conventional methods. (author)

  19. The application of small-angle neutron scattering to the study of mass transfer in clays

    International Nuclear Information System (INIS)

    Allen, A.J.; Baston, A.H.; Bourke, P.J.; Jefferies, N.L.

    1990-01-01

    An extensive study using small angle neutron scattering (SANS) has been made of the pore structures in London Clay and in Ca-montmorillonite. Using SANS contrast variation techniques, the accessibilities of the pores to D 2 O by diffusion and permeation have been studied. Characterisation of the accessibility to different parts of the pore structure is intended to provide input data for models of radionuclide transport through clay geological barriers, and to improve interpretation of laboratory experiments that measure sorption of radionuclides on clays. (author)

  20. Diazonium cation-exchanged clay: an efficient, unfrequented route for making clay/polymer nanocomposites.

    Science.gov (United States)

    Salmi, Zakaria; Benzarti, Karim; Chehimi, Mohamed M

    2013-11-05

    We describe a simple, off-the-beaten-path strategy for making clay/polymer nanocomposites through tandem diazonium salt interface chemistry and radical photopolymerization. Prior to photopolymerization, sodium montmorillonite (MMT) was ion exchanged with N,N'-dimethylbenzenediazonium cation (DMA) from the tetrafluoroborate salt precursor. DMA acts as a hydrogen donor for benzophenone in solution; this pair of co-initiators permits us to photopolymerize glycidyl methacrylate (GMA) between the lamellae of the diazonium-modified clay, therefore providing intercalated MMT-PGMA nanocomposites with an onset of exfoliation. This work conclusively provides a new approach for bridging reactive and functional polymers to layered nanomaterials via aryl diazonium salts in a simple, fast, efficient cation-exchange approach.

  1. Improving the Mechanical Performance and Thermal Stability of a PVA-Clay Nanocomposite by Electron Beam Irradiation

    Science.gov (United States)

    Shokuhi Rad, A.; Ebrahimi, D.

    2017-07-01

    The effects of electron beam irradiation and presence of clay on the mechanical properties and thermal stability of montmorillonite clay-modified polyvinyl alcohol nanocomposites were studied. By using the X-ray diffraction (XRD) and transmission electron microscopy (TEM), the microstructure of the nanocomposites was investigated. The results obtained from TEM and XRD tests showed that montmorillonite clay nanoparticles were located in the polyvinyl alcohol phase. The XRD analysis confirmed the formation of an exfoliated structure in nanocomposites samples. Increasing the amount of clay to 20 wt.% increased the tensile strength and modulus of the nanocomposite. Irradiation up to an absorbed dose of 100 kGy increased its mechanical properties and thermal stability, but at higher irradiation levels, the mechanical strength and thermal stability declined. The sample with 20 wt.% of the nanofiller, exposed to 100 kGy, showed the highest mechanical strength and thermal stability.

  2. Experimental design applied optimization of a state in epoxy clay dispersion; Planejamento de experimentos aplicado a otimizacao do estado de dispersao de argilas em epoxi

    Energy Technology Data Exchange (ETDEWEB)

    Paz, Juliana D' Avila; Bertholdi, Jonas; Folgueras, Marilena Valadares; Pezin, Sergio Henrique; Coelho, Luiz Antonio Ferreira, E-mail: julianadpaz@yahoo.com.b [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas

    2010-07-01

    This paper presents some analysis showed that the exfoliation / intercalation of a montmorillonite clay in epoxy resin such as viscosity, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetry (TG). Increasing the viscosity of epoxy resin diglycidyl ether bisphenol A with the addition of clay associated with the sonification system at the time of dispersion is a good indication of exfoliation. The X-ray diffraction already cured composite shows a decrease of crystallinity of clay and EDS microanalysis of SEM, non-uniform dispersion of clay in epoxy resin. Thermal analysis TG composite clay / epoxy shows an increase in thermal stability relative to pure epoxy. (author)

  3. Adsorption of ferrous ions onto montmorillonites

    Science.gov (United States)

    Qin, Dawei; Niu, Xia; Qiao, Min; Liu, Gang; Li, Hongxin; Meng, Zhenxiao

    2015-04-01

    The adsorption of Fe (II) onto montmorillonites was investigated through initial concentration, contact time, pH and temperature. During the whole adsorption process, the ascorbic acid (Vitamin C) was added as a kind of antioxidant, at the same time, deionized water (after boiling) and nitrogen protection were also used to avoid oxidation. The Fe2+/Fetotal ratio of the iron exists in the Fe-montmorillonites was found more than 95%. Two kinetic models, including pseudo-first-order and pseudo-second-order model, were used to analyze the adsorption process of Fe (II) on montmorillonites. The results of our study showed that adsorption process fitted with pseudo-second-order well. Adsorption isotherms showed that Langmuir model was better than Freundlich model. The thermodynamic parameters ΔG0 and ΔH0 were 3.696 kJ/mol and 6.689 kJ/mol (we just gave the values at 298 K), respectively. The positive values at different temperatures showed that the adsorption process was non-spontaneous and endothermic. The characteristics of materials were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Surface area and porosity analyzer, Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC) and Zeta potential distribution.

  4. Polyurethane/organo clay nano composite materials via in-situ polymerization

    International Nuclear Information System (INIS)

    Rehab, A.; Agag, T; Akelah, A.; Shalaby, N.

    2005-01-01

    Polyurethane/organo clay nano composites have been synthesized via in situ polymerization. The organo clay firstly prepared by intercalation of lyamine or amino lauric acid into montmorillonite-clay (MMT) through ion exchange process. The syntheses of polyurethane/organo clay hybrid films containing different ratio of clay were carried out by swelling the organo clay, into diol and diamine or into different kinds of diols, followed by addition of diisocyanate. The nano composites with dispersed structure of MMT was obtained as evidence by scanning electron microscope and x-ray diffraction. X-ray analysis showed that the d-spacing increased to more than 44A since there is no peaks corresponding to do spacing in organo clay with all the ratios (1, 5, 10, 20%). Also, SEM results confirm the dispersion of nanometer silicate layers in the polyurethane matrix. This indicated that the clay was completely exfoliated and homogeneous dispersion in the polyurethane matrix. Also, it was found that the presence of organo clay leads to improvement the mechanical properties. Since, the tensile strength increased with increasing the organo clay contents to 20% by the ratio 194% in compared to the 1H: with 0% organo clay. Also, the elongation is a decreases with increasing the organo clay contents. The results shown the tensile strength of PU/SMA/ALA-MMT nano composites is high by 6-7 times than the corresponding to PU/Tvr-MMT

  5. Mobility of adsorbed Cry1Aa insecticidal toxin from Bacillus thuringiensis (Bt) on montmorillonite measured by fluorescence recovery after photobleaching (FRAP)

    Science.gov (United States)

    Helassa, Nordine; Daudin, Gabrielle; Noinville, Sylvie; Janot, Jean-Marc; Déjardin, Philippe; Staunton, Siobhán; Quiquampoix, Hervé

    2010-06-01

    The insecticidal toxins produced by genetically modified Bt crops are introduced into soil through root exudates and tissue decomposition and adsorb readily on soil components, especially on clays. This immobilisation and the consequent concentration of the toxins in "hot spots" could increase the exposure of soil organisms. Whereas the effects on non-target organisms are well documented, few studies consider the migration of the toxin in soil. In this study, the residual mobility of Bt Cry1Aa insecticidal toxin adsorbed on montmorillonite was assessed using fluorescence recovery after photobleaching (FRAP). This technique, which is usually used to study dynamics of cytoplasmic and membrane molecules in live cells, was applied for the first time to a protein adsorbed on a finely divided swelling clay mineral, montmorillonite. No mobility of adsorbed toxin was observed at any pH and at different degrees of surface saturation.

  6. Preparation and characterisation of polyamide 11/montmorillonite (MMT) nanocomposites for use in angioplasty balloon applications

    International Nuclear Information System (INIS)

    Halim, Khairul Anwar A.; Farrell, Joseph B.; Kennedy, James E.

    2013-01-01

    With increased demands on catheter balloon functionality, there is an emphasis to blend new materials which can improve mechanical performance. Polymer nanocomposites were prepared by melt blending polyamide 11 (PA 11) with organically modified montmorillonite nanoclay. The effects of incorporating the nanoclay on the short-term mechanical properties of PA 11 were assessed using a design of experiments (DoEs) approach. X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis techniques (DMA) were used to characterise the morphology of the nanocomposites. Design of experiments studies revealed that the optimum nanocomposites properties can be achieved by carefully controlling the melt compounding parameters. XRD and TEM data proved that exfoliated clay morphologies existed within the matrix at low clay loading (2%). Whereas the interaction between the polymer matrix and nanoclay was quantified in the DMA spectra, showed a significant increase in storage modulus (up to 80%). The reinforcing effect of nanoclay within the PA 11 was further investigated using mechanical testing, where significant increases in the ultimate tensile strength and strain at break of reinforced tri-layer balloon tubing were observed. - Highlights: • TEM reveals the coexistence of exfoliated and intercalated nanostructures. • Isothermal crystallisation studies found that the nano-clays reduced the crystallisation time. • Significant increase in the storage modulus was due to the reinforcing effect of the nano-clay platelets. • It was observed that the activation energy values decreased due to the presence of nanoclay

  7. Preparation and characterisation of polyamide 11/montmorillonite (MMT) nanocomposites for use in angioplasty balloon applications

    Energy Technology Data Exchange (ETDEWEB)

    Halim, Khairul Anwar A. [Department of Polymer Engineering, Athlone Institute of Technology, Athlone (Ireland); School of Materials Engineering, Universiti Malaysia Perlis, Perlis (Malaysia); Farrell, Joseph B. [Department of Polymer Engineering, Athlone Institute of Technology, Athlone (Ireland); Kennedy, James E., E-mail: jkennedy@ait.ie [Department of Polymer Engineering, Athlone Institute of Technology, Athlone (Ireland)

    2013-12-16

    With increased demands on catheter balloon functionality, there is an emphasis to blend new materials which can improve mechanical performance. Polymer nanocomposites were prepared by melt blending polyamide 11 (PA 11) with organically modified montmorillonite nanoclay. The effects of incorporating the nanoclay on the short-term mechanical properties of PA 11 were assessed using a design of experiments (DoEs) approach. X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis techniques (DMA) were used to characterise the morphology of the nanocomposites. Design of experiments studies revealed that the optimum nanocomposites properties can be achieved by carefully controlling the melt compounding parameters. XRD and TEM data proved that exfoliated clay morphologies existed within the matrix at low clay loading (2%). Whereas the interaction between the polymer matrix and nanoclay was quantified in the DMA spectra, showed a significant increase in storage modulus (up to 80%). The reinforcing effect of nanoclay within the PA 11 was further investigated using mechanical testing, where significant increases in the ultimate tensile strength and strain at break of reinforced tri-layer balloon tubing were observed. - Highlights: • TEM reveals the coexistence of exfoliated and intercalated nanostructures. • Isothermal crystallisation studies found that the nano-clays reduced the crystallisation time. • Significant increase in the storage modulus was due to the reinforcing effect of the nano-clay platelets. • It was observed that the activation energy values decreased due to the presence of nanoclay.

  8. Functional properties of extruded nano composites based on cassava starch, polyvinyl alcohol and montmorillonite

    International Nuclear Information System (INIS)

    Debiagi, Flavia; Matsuda, Daniel K.M.; Marengo, Vitor A.; Vercelheze, Ana Elisa S.; Mali, Suzana

    2011-01-01

    The objectives of this work were to produce biodegradable trays based on cassava starch (native or modified by acid), sugarcane fibers and nano clay (sodium montmorillonite) and also to characterize the produced trays according to their density, tensile strength, X-ray diffraction and biodegradability. The trays were obtained by thermoforming into a hydraulic press coupled to a Teflon mold (18 x 23 cm) at 130 degree C/ 20 min and 100 bars of pressure. The peak related to the nano clay (2 = 7.1 o ) were not observed in XRD patterns of the trays, suggesting the formation of an exfoliated structure in the nano composite. The addition of modified starch increased tensile strength and density of the samples, and the addition of fibers and nano clays decreased the tensile strength of native and modified starch trays. The weight loss of trays was not affected by the starch type, however the addition of fibers increased the biodegradation and the addition of nano clays decreased. (author)

  9. Electrospun composite matrices of poly(ε-caprolactone)-montmorillonite made using tenside free Pickering emulsions.

    Science.gov (United States)

    Samanta, Archana; Takkar, Sonam; Kulshreshtha, Ritu; Nandan, Bhanu; Srivastava, Rajiv K

    2016-12-01

    The production of composite electrospun matrices of poly(ε-caprolactone) (PCL) using an emulsifier-free emulsion, made with minimal organic solvent, as precursor is reported. Pickering emulsions of PCL were prepared using modified montmorillonite (MMT) clay as the stabilizer. Hydrophobic tallow group of the modified MMT clay resulted in analogous interaction of clay with oil and aqueous phase and its adsorption at the interface to provide stability to the resultant emulsion. Composite fibrous matrices of PCL and MMT were produced using electrospinning under controlled conditions. The fiber fineness was found to alter with PCL concentration and volume fraction of the aqueous and oil phases. A higher tensile strength and modulus was obtained with inclusion of MMT in PCL electrospun matrix in comparison to a matrix made using neat PCL. The presence of clay in the fibrous matrix did not change the cell proliferation efficiency in comparison to neat PCL matrix. Composite fibrous matrices of PCL/MMT bearing enhanced tensile properties may find applications in areas other than tissue engineering for example food packaging and filtration. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Application of short-wave infrared (SWIR) spectroscopy in quantitative estimation of clay mineral contents

    International Nuclear Information System (INIS)

    You, Jinfeng; Xing, Lixin; Pan, Jun; Meng, Tao; Liang, Liheng

    2014-01-01

    Clay minerals are significant constituents of soil which are necessary for life. This paper studied three types of clay minerals, kaolinite, illite, and montmorillonite, for they are not only the most common soil forming materials, but also important indicators of soil expansion and shrinkage potential. These clay minerals showed diagnostic absorption bands resulting from vibrations of hydroxyl groups and structural water molecules in the SWIR wavelength region. The short-wave infrared reflectance spectra of the soil was obtained from a Portable Near Infrared Spectrometer (PNIS, spectrum range: 1300∼2500 nm, interval: 2 nm). Due to the simplicity, quickness, and the non-destructiveness analysis, SWIR spectroscopy has been widely used in geological prospecting, chemical engineering and many other fields. The aim of this study was to use multiple linear regression (MLR) and partial least squares (PLS) regression to establish the optimizing quantitative estimation models of the kaolinite, illite and montmorillonite contents from soil reflectance spectra. Here, the soil reflectance spectra mainly refers to the spectral reflectivity of soil (SRS) corresponding to the absorption-band position (AP) of kaolinite, illite, and montmorillonite representative spectra from USGS spectral library, the SRS corresponding to the AP of soil spectral and soil overall spectrum reflectance values. The optimal estimation models of three kinds of clay mineral contents showed that the retrieval accuracy was satisfactory (Kaolinite content: a Root Mean Square Error of Calibration (RMSEC) of 1.671 with a coefficient of determination (R 2 ) of 0.791; Illite content: a RMSEC of 1.126 with a R 2 of 0.616; Montmorillonite content: a RMSEC of 1.814 with a R 2 of 0.707). Thus, the reflectance spectra of soil obtained form PNIS could be used for quantitative estimation of kaolinite, illite and montmorillonite contents in soil

  11. [Mechanism of tritium persistence in porous media like clay minerals].

    Science.gov (United States)

    Wu, Dong-Jie; Wang, Jin-Sheng; Teng, Yan-Guo; Zhang, Ke-Ni

    2011-03-01

    To investigate the mechanisms of tritium persistence in clay minerals, three types of clay soils (montmorillonite, kaolinite and illite) and tritiated water were used in this study to conduct the tritium sorption tests and the other related tests. Firstly, the ingredients, metal elements and heat properties of clay minerals were studied with some instrumental analysis methods, such as ICP and TG. Secondly, with a specially designed fractionation and condensation experiment, the adsorbed water, the interlayer water and the structural water in the clay minerals separated from the tritium sorption tests were fractionated for investigating the tritium distributions in the different types of adsorptive waters. Thirdly, the location and configuration of tritium adsorbed into the structure of clay minerals were studied with infrared spectrometry (IR) tests. And finally, the forces and mechanisms for driving tritium into the clay minerals were analyzed on the basis of the isotope effect of tritium and the above tests. Following conclusions have been reached: (1) The main reason for tritium persistence in clay minerals is the entrance of tritium into the adsorbed water, the interlayer water and the structural water in clay minerals. The percentage of tritium distributed in these three types of adsorptive water are in the range of 13.65% - 38.71%, 0.32% - 5.96%, 1.28% - 4.37% of the total tritium used in the corresponding test, respectively. The percentages are different for different types of clay minerals. (2) Tritium adsorbed onto clay minerals are existed in the forms of the tritiated hydroxyl radical (OT) and the tritiated water molecule (HTO). Tritium mainly exists in tritiated water molecule for adsorbed water and interlayer water, and in tritiated hydroxyl radical for structural water. (3) The forces and effects driving tritium into the clay minerals may include molecular dispersion, electric charge sorption, isotope exchange and tritium isotope effect.

  12. Clay-Enriched Silk Biomaterials for Bone Formation

    Science.gov (United States)

    Mieszawska, Aneta J.; Llamas, Jabier Gallego; Vaiana, Christopher A.; Kadakia, Madhavi P.; Naik, Rajesh R.; Kaplan, David L.

    2011-01-01

    The formation of silk protein/clay composite biomaterials for bone tissue formation is described. Silk fibroin serves as an organic scaffolding material offering mechanical stability suitable for bone specific uses. Clay montmorillonite (Cloisite ® Na+) and sodium silicate are sources of osteoinductive silica-rich inorganic species, analogous to bioactive bioglass-like bone repair biomaterial systems. Different clay particle-silk composite biomaterial films were compared to silk films doped with sodium silicate as controls for support of human bone marrow derived mesenchymal stem cells (hMSCs) in osteogenic culture. The cells adhered and proliferated on the silk/clay composites over two weeks. Quantitative real-time RT-PCR analysis revealed increased transcript levels for alkaline phosphatase (ALP), bone sialoprotein (BSP), and collagen type 1 (Col I) osteogenic markers in the cells cultured on the silk/clay films in comparison to the controls. Early evidence for bone formation based on collagen deposition at the cell-biomaterial interface was also found, with more collagen observed for the silk films with higher contents of clay particles. The data suggest that the silk/clay composite systems may be useful for further study toward bone regenerative needs. PMID:21549864

  13. The reaction of 1-tetralones with thallium trinitrate supported on clay: ring contraction vs a-oxidation

    Directory of Open Access Journals (Sweden)

    Ferraz Helena M. C.

    2001-01-01

    Full Text Available The reaction of a series of 1-tetralones with thallium trinitrate supported on Montmorillonite K-10 clay led to products of ring contraction (methyl indan-1-carboxylates and/or alpha-oxidation (2-methoxy-1-tetralones, in variable yields.

  14. 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.

  15. Effect of dry density and salinity on Cl- diffusion of compacted Na-montmorillonite

    International Nuclear Information System (INIS)

    Goto, T.; Gorai, M.; Kozaki, T.; Sato, S.

    2010-01-01

    Document available in extended abstract form only. Compacted bentonite is candidate buffer material in geological disposal of high-level radioactive waste (HLW). One of the expected functions of the buffer is to retard the migration of radionuclides from waste form to biosphere. Due to low hydraulic conductivity of the compacted bentonite, diffusion is considered to be predominant process in radionuclide migrations. Therefore, it is important for safety assessment of the geological disposal to clarify the diffusion behavior of radionuclides in montmorillonite, which is a major clay mineral of bentonite. However, detail diffusion mechanism has not been fully understood especially for the compacted bentonite saturated with groundwater having relatively high salt concentration. In this study, apparent diffusion coefficient (D a [m 2 s -1 ]) of Cl- ions was determined by one-dimensional, non-steady diffusion method for Na-montmorillonite saturated with NaCl solutions with different concentrations. Activation energy for Cl - diffusion (E a [kJ mol -1 ]) was also obtained from the temperature dependence of Da at each NaCl concentration. Based on these experimental results together with the basal spacing of the montmorillonite determined by XRD measurements, the diffusion mechanism of Cl - ions was discussed. The montmorillonite used in this study was Kunipia-F, a commercial product of Kunimine Industries Co. Ltd., Japan. The montmorillonite sample was homo-ionized into Na-type before use. The Na-montmorillonite was compacted into an acrylic resin cell (20 mm in diameter, 20 mm in height for diffusion experiment or 10 mm in height for XRD measurement) and fully saturated with NaCl solutions of concentration from 0 to 0.5 M. The dry densities of the Na-montmorillonite were 1.0 and 1.3 Mg m -3 for diffusion experiments, and from 0.7 to 1.4 Mg m -3 for the XRD measurements. The apparent diffusion coefficients of 36 Cl - ions in the solution-saturated, compacted

  16. Influence of herbicide structure, clay acidity, and humic acid coating on acetanilide herbicide adsorption on homoionic clays.

    Science.gov (United States)

    Liu, Weiping; Gan, Jianying; Yates, Scott R

    2002-07-03

    Adsorption of chloroacetanilide herbicides on homoionic montmorillonite was studied by coupling batch equilibration and FT-IR analysis. Adsorption decreased in the order metolachlor > acetochlor > alachlor > propachlor on Ca(2+)- or Mg(2+)-saturated clays and in the order metolachlor > alachlor > acetachlor > propachlor on Al(3+)- or Fe(3+)-saturated clays. FT-IR spectra showed that the carbonyl group of the herbicide molecule was involved in bonding. For the same herbicide, adsorption of alachlor, acetachlor, and metolachlor on clay followed the order Ca(2+) approximately Mg(2+) < Al(3+) < or = Fe(3+), which coincided with the increasing acidity of homoionic clays. Adsorption of propachlor, however, showed an opposite dependence, suggesting a different governing interaction. In clay and humic acid mixtures, herbicide adsorption was less than that expected from independent additive adsorption by the individual constituents, and the deviation was dependent on the clay-to-humic acid ratio, with the greatest deviation consistently occurring at a 60:40 clay-to-humic acid ratio.

  17. Synthesis of Various Polyaniline / Clay Nanocomposites Derived from Aniline and Substituted Aniline Derivatives by Mechanochemical Intercalation Method

    Directory of Open Access Journals (Sweden)

    N. Kalaivasan

    2010-01-01

    Full Text Available Polyaniline clay nanocomposite can be prepared by mechano-chemical method in which intercalation of anilinium ion into the clay lattices accomplished by mechanical grinding of sodium montmorillonite (Na+MMT in presence of anilinium hydrochloride at room temperature using mortar & pestle for about 30 min and subsequent grinding with oxidizing agent, ammonium peroxysulfate. The appearance of green colour indicates the formation of polyaniline/clay nanocomposite (PANI/Clay. Similarly aniline derivatives like o-toludine and o-anisidine in the form of HCl salt can form intercalation into the clay lattices. The intercalated aniline derivatives were ground mechanically in presence of oxidizing agent ammonium peroxysulfate lead to formation of substituted polyaniline/ clay nanocomposites. The characteristics of various polyaniline-clay nanocomposites were investigated using UV-Visible, FT-IR, cyclic voltammetry studies.

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

    Science.gov (United States)

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

    2013-12-01

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

  19. Adsorption of Lysine on Na-Montmorillonite and Competition with Ca(2+): A Combined XRD and ATR-FTIR Study.

    Science.gov (United States)

    Yang, Yanli; Wang, Shengrui; Liu, Jingyang; Xu, Yisheng; Zhou, Xiaoyun

    2016-05-17

    Lysine adsorption at clay/aqueous interfaces plays an important role in the mobility, bioavailability, and degradation of amino acids in the environment. Knowledge of these interfacial interactions facilitates our full understanding of the fate and transport of amino acids. Here, X-ray diffraction (XRD) and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) measurements were used to explore the dynamic process of lysine adsorption on montmorillonite and the competition with Ca(2+) at the molecular level. Density functional theory (DFT) calculations were employed to determine the peak assignments of dissolved lysine in the solution phase. Three surface complexes, including dicationic, cationic, and zwitterionic structures, were observed to attach to the clay edge sites and penetrate the interlayer space. The increased surface coverage and Ca(2+) competition did not affect the interfacial lysine structures at a certain pH, whereas an elevated lysine concentration contributed to zwitterionic-type coordination at pH 10. Moreover, clay dissolution at pH 4 could be inhibited at a higher surface coverage with 5 and 10 mM lysine, whereas the inhibition effect was inconspicuous or undetected at pH 7 and 10. The presence of Ca(2+) not only could remove a part of the adsorbed lysine but also could facilitate the readsorption of dissolved Si(4+) and Al(3+) and surface protonation. Our results provide new insights into the process of lysine adsorption and its effects on montmorillonite surface sites.

  20. Effect of organo-modified montmorillonite on poly(butylene succinate/poly(butylene adipate-co-terephthalate nanocomposites

    Directory of Open Access Journals (Sweden)

    2010-07-01

    Full Text Available The composite material based on poly(butylene succinate (PBS, poly(butylene adipate-co-terephthalate (PBAT and organo-modified montmorillonite (OMMT were prepared by melt blending technique and characterized. Sodium montmorillonite (Na-MMT was successfully modified by octadecylammonium (ODA and dimethyldioctadecylammonium (DDOA salts to become OMMT through cation exchange technique which is shown by the increase of basal spacing of clay by XRD. The addition of the OMMT to the PBS/PBAT blends produced nanocomposites which is proved by XRD and TEM. Tensile tests showed increase in tensile strength and modulus which is attributed to the existence of strong interactions between PBS/PBAT and clay, particularly with OMMT. Highest tensile strength of nanocomposite was observed at 1 wt% of OMMT incorporated. TGA study showed that the thermal stability of the blend increased after the addition of clays. SEM micrographs of the fracture surfaces show that the morphology of the blend becomes homogeneous and smoother with presence of OMMT.

  1. Monte Carlo studies of TPP+ and BE+ arrangements in the interlayer and at the external surface of montmorillonite

    International Nuclear Information System (INIS)

    Jeschke, F.; Meleshyn, A.

    2010-01-01

    Document available in extended abstract form only. Unlike natural clay minerals, organically modified montmorillonite possesses a very high sorption capacity for anions, which favors its use for waste storage and sewage purposes. Understanding of this anion sorption requires a detailed knowledge about the underlying structure, which is only partially accessible with currently applied experimental methods. To get more structural information, Na-montmorillonite modified with tetraphenyl-phosphonium (TPP + , (C 6 H 5 ) 4 P + ) chloride or benzethonium (BE + , C 27 H 42 O 2 N + ) chloride was simulated using the Metropolis Monte Carlo method as extended by the configurational-bias procedure for flexible organic molecules. The simulated interlayer content of TPP + varied between 8% and 100% of CEC (cation exchange capacity). Two different initial arrangements of TPP + were considered, taking into account experimentally derived suggestions: 1) 'mono-facial' arrangement with three of the phenyl groups of all TPP + aligned to the same basal surface, and 2) 'bi-facial' arrangement with an equivalent distribution of phenyl groups between the two opposite basal surfaces of the montmorillonite. Pressure, temperature and number of particles were kept constant whereas the layer spacing was allowed to vary during the simulations. The OPLS-AA force field was used for calculation of the intermolecular and intramolecular interactions and Ewald summation was used to calculate the electrostatic interactions. The layer spacings, determined for the first arrangement, are between 17.4 A for the lowest and 19 A for the highest TPP + contents and show a very good agreement with experimental values. For this arrangement, a segregation of organic (TPP + ) and inorganic (Na + , Cl - and H 2 O) phases is observed. On the contrary, the simulated layer spacings for the second arrangement agree with the experimental data only for lower contents of TPP + . For higher contents

  2. Investigations on uranium sorption on bentonite and montmorillonite, respectively, and uranium in environmental samples; Untersuchungen zur Uransorption an Bentonit bzw. Montmorillonit sowie von Uran in Umweltproben

    Energy Technology Data Exchange (ETDEWEB)

    Azeroual, Mohamed

    2010-09-22

    The geotechnical barrier is an important component of a geological repository and consists of compacted bentonite surrounding radioactive waste containers. Its most important functions are, to retard the radionuclide migration into the biosphere and to prevent groundwater contact with containers. lt is therefore of central importance to investigate the bentonite material on its capacity to sorb radionuclides under near-natural chemical and physical conditions. The purpose of this work was to study the adsorption of uranium(VI) on bentonit and on montmorillonite-standards at high uranium concentrations. Thereby, a special account was given to the calcium-uranyl-carbonate complexation, which leads to the formation of very stable and mobile uncharged Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3} complex. Results of batch experiments showed that the dicalcium-uranyl-tricarbonate complexation lowers the uranium(VI) sorption on natural clay (bentonite) by a factor of up to 3. After 21 days of contact time, about 40 % and 20 % of the initial uranium(VI)concentration were sorbed on Na-bentonite and ea-bentonite, respectively, from a solution with Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3} dominating the uranium(VI) speciation. On the contrary, about 55 % of the initial uranium(VI)-concentration were sorbed on thes clays from the solution, in which (UO{sub 2}){sub 2}CO{sub 3}(OH){sub 3}{sup -} complex dominated the uranium(VI) speciation. Thus uranium(VI) sorption is more strongly influenced by the solution composition than by bentonite type. Na-bentonite should be used instead of ea-bentonite as a geotechnical barrier, since calcium-uranyl-carbonate complexation may be a realistic scenario. Further SEM-EDX and HREM-EDX studies showed that uranium(VI) sorption occurred predominantly on montmorillonite, which is the main component of bentonite. Uranium(VI) sorption on bentonite's accessory Minerals (pyrite, calcite, mica, and feldspar) was not observed. Investigation of uranium

  3. Hydrophobic Modification of Layered Clays and Compatibility for Epoxy Nanocomposites

    Directory of Open Access Journals (Sweden)

    Jiang-Jen Lin

    2010-04-01

    Full Text Available Recent studies on the intercalation and exfoliation of layered clays with polymeric intercalating agents involving poly(oxypropylene-amines and the particular uses for epoxy nanocomposites are reviewed. For intercalation, counter-ionic exchange reactions of clays including cationic layered silicates and anionic Al-Mg layered double hydroxide (LDH with polymeric organic ions afforded organoclays led to spatial interlayer expansion from 12 to 92 Å (X-ray diffraction as well as hydrophobic property. The inorganic clays of layered structure could be modified by the poly(oxypropyleneamine-salts as the intercalating agents with molecular weights ranging from 230 to 5,000 g/mol. Furthermore, natural montmorillonite (MMT clay could be exfoliated into thin layer silicate platelets (ca. 1 nm thickness in one step by using polymeric types of exfoliating agents. Different lateral dimensions of MMT, synthetic fluorinated Mica and LDH clays had been cured into epoxy nanocomposites. The hydrophobic amine-salt modification resulting in high spacing of layered or exfoliation of individual clay platelets is the most important factor for gaining significant improvements of properties. In particular, these modified clays were reported to gain significant improvements such as reduced coefficient of thermal expansion (CTE, enhanced thermal stability, and hardness. The utilization of these layered clays for initiating the epoxy self-polymerization was also reported to have a unique compatibility between clay and organic resin matrix. However, the matrix domain lacks of covalently bonded crosslink and leads to the isolation of powder material. It is generally concluded that the hydrophobic expansion of the clay inter-gallery spacing is the crucial step for enhancing the compatibility and the ultimate preparation of the advanced epoxy materials.

  4. Hydrophobic Modification of Layered Clays and Compatibility for Epoxy Nanocomposites

    Science.gov (United States)

    Lin, Jiang-Jen; Chan, Ying-Nan; Lan, Yi-Fen

    2010-01-01

    Recent studies on the intercalation and exfoliation of layered clays with polymeric intercalating agents involving poly(oxypropylene)-amines and the particular uses for epoxy nanocomposites are reviewed. For intercalation, counter-ionic exchange reactions of clays including cationic layered silicates and anionic Al-Mg layered double hydroxide (LDH) with polymeric organic ions afforded organoclays led to spatial interlayer expansion from 12 to 92 Å (X-ray diffraction) as well as hydrophobic property. The inorganic clays of layered structure could be modified by the poly(oxypropylene)amine-salts as the intercalating agents with molecular weights ranging from 230 to 5,000 g/mol. Furthermore, natural montmorillonite (MMT) clay could be exfoliated into thin layer silicate platelets (ca. 1 nm thickness) in one step by using polymeric types of exfoliating agents. Different lateral dimensions of MMT, synthetic fluorinated Mica and LDH clays had been cured into epoxy nanocomposites. The hydrophobic amine-salt modification resulting in high spacing of layered or exfoliation of individual clay platelets is the most important factor for gaining significant improvements of properties. In particular, these modified clays were reported to gain significant improvements such as reduced coefficient of thermal expansion (CTE), enhanced thermal stability, and hardness. The utilization of these layered clays for initiating the epoxy self-polymerization was also reported to have a unique compatibility between clay and organic resin matrix. However, the matrix domain lacks of covalently bonded crosslink and leads to the isolation of powder material. It is generally concluded that the hydrophobic expansion of the clay inter-gallery spacing is the crucial step for enhancing the compatibility and the ultimate preparation of the advanced epoxy materials.

  5. Study of the morphology exhibited by exfoliated polyurethane/montmorillonite nano composites during in situ recovery tests

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Iaci M., E-mail: iaci@ctex.eb.br [Divisao Belica do Centro Tecnologico do Exercito. CTEx, Rio de Janeiro, RJ (Brazil); Orefice, Rodrigo L. [Universidade Federal de Minas Gerais Departamento de Metalurgia e Materiais. UFMG, Belo Horizonte, MG (Brazil)

    2011-07-01

    By using small-angle X-ray scattering, this study aims to examine the SM behavior of montmorillonite polyurethane nano composites. To investigate the phase morphology, a deformed specimen was placed on a heating stage mounted at the Synchrotron beamline; the shape recovery was measured during 15 min. As temperature increases, the crystalline fraction rapidly decreases. The degree of clay delamination within the matrix increases, disturbing the formation of hard and soft segments. Deformation induces changes in the phase proportion, increasing the disperse phase contribution. During in situ tests, the ratio between matrix and disperse phase reaches an equilibrium controlled by the temperature. (author)

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

    Directory of Open Access Journals (Sweden)

    Simona eLongo

    2013-11-01

    Full Text Available Supercritical carbon dioxide (scCO2 treatments of a montmorillonite (MMT intercalated with ammonium cations bearing two long hydrocarbon tails (organo-modified MMT, OMMT led to OMMT exfoliation, with loss of the long-range order in the packing of the hydrocarbon tails and maintenance of the long-range order in the clay layers. The intercalated and the derived exfoliated OMMT have been deeply characterized, mainly by X-ray diffraction analyses. Monolithic composite aerogels, with large amounts of both intercalated and exfoliated OMMT and including the nanoporous-crystalline δ form of syndiotactic polystyrene (s-PS, have been prepared, by scCO2 extractions of s-PS-based gels. Also for high OMMT content, the gel and aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Aerogels with the exfoliated OMMT have more even dispersion of the clay layers, higher elastic modulus and larger surface area than aerogels with the intercalated OMMT. Extremely light materials with relevant transport properties could be prepared. Moreover, s-PS-based aerogels with exfoliated OMMT could be helpful for the handling of exfoliated clay minerals.

  7. Modification of montmorillonite fillers by ionizing radiation

    International Nuclear Information System (INIS)

    Zimek, Z.; Przybytniak, G.; Nowicki, A.; Mirkowski, K.

    2006-01-01

    The mineral fillers can be modified by using unsaturated compounds: styrene, methacrylic acid and maleic anhydride (MA), following by irradiation with high energy electron beam. In presented paper the authors have used this method to change properties of bentonite S pecjal , containing about 70% of pure montmorillonite. It has been shown that: (a) the particles obtained in this process can be good fillers for the production of composites; (b) maleic anhydride reacts via anhydride group with active ionic sites of bentonite, forming a salt-like compound. Irradiation with electron beam leads to the breakage of double bond in maleic anhydride and to the production of new organic phases

  8. Spectromicroscopy of Fe distributions in clay microcrystals

    Energy Technology Data Exchange (ETDEWEB)

    Grundl, T. [Univ. of Wisconsin, Milwaukee, WI (United States); Cerasari, S.; Garcia, A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Clays are ubiquitous crystalline particles found in nature that are responsible for contributing to a wide range of chemical reactions in soils. The structure of these mineral particles changes when the particle is hydrated ({open_quotes}wet{close_quotes}), from that when it is dry. This makes a study of the microscopic distribution of chemical content of these nanocrystals difficult using standard techniques that require vacuum. In addition to large structural changes, it is likely that chemical changes accompany the drying process. As a result, spectroscopic measurements on dried clay particles may not accurately reflect the actual composition of the material as found in the environment. In this work, the authors extend the use of the ALS Spectromicroscopy Facility STXM to high spectral and spatial resolution studies of transition metal L-edges in environmental materials. The authors are studying mineral particles of montmorillonite, which is an Fe bearing clay which can be prepared with a wide distribution of Fe concentrations, and with Fe occupying different substitutional sites.

  9. Degradation of surfactant-modified montmorillonites in HCl

    International Nuclear Information System (INIS)

    Madejová, Jana; Pálková, Helena; Jankovič, Ľuboš

    2012-01-01

    The effect of surfactant size on the extent of montmorillonites decomposition in HCl was investigated. Na-SAz montmorillonite and tetraalkylammonium salts of alkyl-chains length increasing from methyl- Me 4 N to pentyl- Pe 4 N were used for organo-montmorillonites preparation. Decreasing intensity of d 001 diffraction proved destruction of montmorillonite structure connected with gradual surfactant release. A shift of the SiO stretching band to 1097 cm −1 confirmed formation of amorphous silica phase. A new band near 7315 cm −1 corresponding to SiOH overtone revealed creation of protonated silica. This band was observed in the spectra of all acid-treated samples, also in those with minor decomposition of the structure. The size of the cations significantly affected decomposition of montmorillonites in HCl. The less stable were Na-SAz and Me 4 N-SAz in which the content of octahedral atoms dropped to ∼5% of their original values upon 8 h treatments. Et 4 N-SAz and Pr 4 N-SAz were slightly more resistant mainly at short times. Bu 4 N-SAz and Pe 4 N-SAz showed the least structural modifications, only 50% and 35% of octahedral atoms, respectively, were released into solution within 8 h treatments. This observation proves that bulky alkylammonium cations covering the inner and outer surfaces of montmorillonite prevent effectively the access of protons to the layers protecting the mineral from degradation in the acid. - Highlights: ► Hybrid materials were prepared from montmorillonite and alkylammonium cations with short alkyl chains. ► The effect of surfactant on organo-montmorillonites dissolution in HCl was studied. ► With increasing size of cation the extent of montmorillonite decomposition decreased. ► Bulky surfactants prevent the access of protons to the layers and thus protect montmorillonite from degradation.

  10. Impact of biostimulated redox processes on metal dynamics in an iron-rich creek soil of a former uranium mining area.

    Science.gov (United States)

    Burkhardt, Eva-Maria; Akob, Denise M; Bischoff, Sebastian; Sitte, Jana; Kostka, Joel E; Banerjee, Dipanjan; Scheinost, Andreas C; Küsel, Kirsten

    2010-01-01

    Understanding the dynamics of metals and radionuclides in soil environments is necessary for evaluating risks to pristine sites. An iron-rich creek soil of a former uranium-mining district (Ronneburg, Germany) showed high porewater concentrations of heavy metals and radionuclides. Thus, this study aims to (i) evaluate metal dynamics during terminal electron accepting processes (TEAPs) and (ii) characterize active microbial populations in biostimulated soil microcosms using a stable isotope probing (SIP) approach. In biostimulated soil slurries, concentrations of soluble Co, Ni, Zn, As, and unexpectedly U increased during Fe(III)-reduction. This suggests that there was a release of sorbed metals and As during reductive dissolution of Fe(III)-oxides. Subsequent sulfate-reduction was concurrent with a decrease of U, Co, Ni, and Zn concentrations. The relative contribution of U(IV) in the solid phase changed from 18.5 to 88.7% after incubation. The active Fe(III)-reducing population was dominated by delta-Proteobacteria (Geobacter) in (13)C-ethanol amended microcosms. A more diverse community was present in (13)C-lactate amended microcosms including taxa related to Acidobacteria, Firmicutes, delta-Proteobacteria, and beta-Proteobacteria. Our results suggested that biostimulated Fe(III)-reducing communities facilitated the release of metals including U to groundwater which is in contrast to other studies.

  11. Performance assessment of laboratory and field-scale multi-step passive treatment of iron-rich acid mine drainage for design improvement.

    Science.gov (United States)

    Rakotonimaro, Tsiverihasina V; Neculita, Carmen Mihaela; Bussière, Bruno; Genty, Thomas; Zagury, Gérald J

    2018-04-17

    Multi-step passive systems for the treatment of iron-rich acid mine drainage (Fe-rich AMD) perform satisfactorily at the laboratory scale. However, their field-scale application has revealed dissimilarities in performance, particularly with respect to hydraulic parameters. In this study, the assessment of factors potentially responsible for the variations in performance of laboratory and field-scale multi-step systems was undertaken. Three laboratory multi-step treatment scenarios, involving a combination of dispersed alkaline substrate (DAS) units, anoxic dolomitic drains, and passive biochemical reactors (PBRs), were set up in 10.7-L columns. The field-scale treatment consisted of two PBRs separated by a wood ash (WA) reactor. The parameters identified as possibly influencing the performances of the laboratory and field-scale experiments were the following: AMD chemistry (electrical conductivity and Fe and SO 4 2- concentrations), flow rate (Q), and saturated hydraulic conductivity (k sat ). Based on these findings, the design of an efficient passive multi-step treatment system is suggested to consider the following: (1) Fe pretreatment, using materials with high k sat and low HRT. If a PBR is to be used, the Fe load should be PBR/DAS filled with a mixture with at least 20% of neutralizing agent; (3) include Q and k sat (> 10 -3  cm/s) in the long-term prediction. Finally, mesocosm testing is strongly recommended prior to construction of full-scale systems for the treatment of Fe-rich AMD.

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

    Science.gov (United States)

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

    2015-04-01

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

  13. Interphase vs confinement in starch-clay bionanocomposites.

    Science.gov (United States)

    Coativy, Gildas; Chevigny, Chloé; Rolland-Sabaté, Agnès; Leroy, Eric; Lourdin, Denis

    2015-03-06

    Starch-clay bionanocomposites containing 1-10% of natural montmorillonite were elaborated by melt processing in the presence of water. A complex macromolecular dynamics behavior was observed: depending on the clay content, an increase of the glass transition temperature and/or the presence of two overlapped α relaxation peaks were detected. Thanks to a model allowing the prediction of the average interparticle distance, and its comparison with the average size of starch macromolecules, it was possible to associate these phenomena to different populations of macromolecules. In particular, it seems that for high clay content (10%), the slowdown of segmental relaxation due to confinement of the starch macromolecules between the clay tactoïds is the predominant phenomenon. While for lower clay contents (3-5%), a significant modification of chain relaxation seems to occur, due to the formation of an interphase by the starch macromolecules in the vicinity of clay nanoparticles coexisting with the bulk polymer. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2009-08-15

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

  15. Rheological properties of different minerals and clay soils

    Directory of Open Access Journals (Sweden)

    Dolgor Khaydapova

    2015-07-01

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

  16. Fabrication of nanostructured clay-carbon nanotube hybrid nanofiller by chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, Dhanagopal, E-mail: dmani_cat@yahoo.co.in [Department of Materials Engineering, Faculty of Engineering, University of Concepcion, Concepcion (Chile); Mangalaraja, Ramalinga Viswanathan, E-mail: mangal@udec.cl [Department of Materials Engineering, Faculty of Engineering, University of Concepcion, Concepcion (Chile); Siddheswaran, Rajendran [Department of Materials Engineering, Faculty of Engineering, University of Concepcion, Concepcion (Chile); Avila, Ricardo E. [Personal Dosimetry Section, Chilean Nuclear Energy Commission, Santiago (Chile); Ananthakumar, Solaiappan [Materials and Minerals Division, National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum, Kerala (India)

    2012-03-01

    Growth of multiwalled carbon nanotube (CNT) assemblies by chemical vapour decomposition (CVD) technique was achieved through decomposition of acetylene using iron impregnated montmorillonite (MM) catalysts. Various amounts of iron loaded montmorillonite catalysts were prepared by wet impregnation method and calcined at 450 Degree-Sign C. The catalysts were subjected to X-ray diffraction (XRD) and surface area analyses. Acetylene decomposition at a feed ratio of N{sub 2}:H{sub 2}:C{sub 2}H{sub 2} = 1:1:0.18 was conducted in the presence of iron impregnated montmorillonite catalysts in the CVD reactor for the growth of CNT structures. The role of Fe-activated clay catalyst on the formation of CNT structures has been systematically examined at various temperatures and correlated with the morphological features of CNTs. Catalyst assisted acetylene decomposition results the formation of different carbon nanostructures such as nanotubes, nanofibres and nanoflakes. These clay-CNT products were characterised for their morphological, thermal, qualitative and quantitative analyses. The morphological variations of CNT assemblies reveal Fe-montmorillonite catalysts have high selectivity at given reaction conditions. Thermogravimetric and Raman spectral analyses prove that the CNTs contain a good crystallanity and less structural defects.

  17. Adsorption of nucleotides onto Fe-Mg-Al rich swelling clays

    Science.gov (United States)

    Feuillie, Cécile; Daniel, Isabelle; Michot, Laurent J.; Pedreira-Segade, Ulysse

    2013-11-01

    Mineral surfaces may have played a role in the origin of the first biopolymers, by concentrating organic monomers from a dilute ocean. Swelling clays provide a high surface area for the concentration of prebiotic monomers, and have therefore been the subject of numerous investigations. In that context, montmorillonite, the most abundant swelling clay in modern environments, has been extensively studied with regard to adsorption and polymerization of nucleic acids. However, montmorillonite was probably rather marginal on the primitive ocean floor compared to iron-magnesium rich phyllosilicates such as nontronite that results from the hydrothermal alteration of a mafic or ultramafic oceanic crust. In the present paper, we study the adsorption of nucleotides on montmorillonite and nontronite, at various pH and ionic strength conditions plausible for Archean sea-water. A thorough characterization of the mineral surfaces shows that nucleotide adsorb mainly on the edge faces of the smectites by ligand exchange between the phosphate groups of the nucleotides and the -OH groups from the edge sites over a wide pH range (4-10). Nontronite is more reactive than montmorillonite. At low pH, additional ion exchange may play a role as the nucleotides become positively charged.

  18. Fabrication of nanostructured clay-carbon nanotube hybrid nanofiller by chemical vapour deposition

    International Nuclear Information System (INIS)

    Manikandan, Dhanagopal; Mangalaraja, Ramalinga Viswanathan; Siddheswaran, Rajendran; Avila, Ricardo E.; Ananthakumar, Solaiappan

    2012-01-01

    Growth of multiwalled carbon nanotube (CNT) assemblies by chemical vapour decomposition (CVD) technique was achieved through decomposition of acetylene using iron impregnated montmorillonite (MM) catalysts. Various amounts of iron loaded montmorillonite catalysts were prepared by wet impregnation method and calcined at 450 °C. The catalysts were subjected to X-ray diffraction (XRD) and surface area analyses. Acetylene decomposition at a feed ratio of N 2 :H 2 :C 2 H 2 = 1:1:0.18 was conducted in the presence of iron impregnated montmorillonite catalysts in the CVD reactor for the growth of CNT structures. The role of Fe-activated clay catalyst on the formation of CNT structures has been systematically examined at various temperatures and correlated with the morphological features of CNTs. Catalyst assisted acetylene decomposition results the formation of different carbon nanostructures such as nanotubes, nanofibres and nanoflakes. These clay-CNT products were characterised for their morphological, thermal, qualitative and quantitative analyses. The morphological variations of CNT assemblies reveal Fe-montmorillonite catalysts have high selectivity at given reaction conditions. Thermogravimetric and Raman spectral analyses prove that the CNTs contain a good crystallanity and less structural defects.

  19. Hybrids of ethylene vinyl acetate with Na-montmorillonite and titania: preparation and characterization

    International Nuclear Information System (INIS)

    Ashfaq, M.

    2010-01-01

    Hybrids of Ethylene vinyl acetate (EVA) with Na-montmorillonite and titania were formed. Montmorillonite was organically modified by two different modifiers: Pyridinium ions and 4. 4-oxydianilinium ions. X-ray diffraction results revealed that Pyridinium ions increased the .interlayer spacing by 0.33 nm and 4, 4-oxydianilinium by 0.55 nm approximately. These modified organo-clays were successfully exfoliated in EVA using melt blending. These hybrids showed improvement in mechanical and thermal properties. 4, 4-oxydianilinium ions were degraded at higher temperature due to which thermal degradation was enhanced in EVA. In addition to this, EVA/titania hybrids were also prepared using sot-gel technique and modified by triethoxy vinyl silane and (3-aminopropyI)- triethoxy silane to increase their compatibility with EVA. Some portion of unmodified titania was heat treated to 600 degree C to obtain particulate titania. The hybrid of particulate titania and modified titania improved the mechanical properties and thermal properties. Especially in case of modified titania toughness was almost doubled. (author)

  20. New insights on the structure of the picloram-montmorillonite surface complexes.

    Science.gov (United States)

    Marco-Brown, Jose L; Trinelli, María Alcira; Gaigneaux, Eric M; Sánchez, Rosa M Torres; Afonso, María dos Santos

    2015-04-15

    The environmental mobility and bioavailability of Picloram (PCM) are determined by the amine and carboxylate chemical groups interaction with the soils mineral phases. Clay particles, such as montmorillonite (Mt), and the pH value of the media could play an important role in adsorption processes. Thus, the study of the role of soil components other than organic matter deserves further investigation for a more accurate assessment of the risk of groundwater contamination. Samples with PCM adsorbed on Mt dispersions were prepared at pH 3-9. Subsequently, the dispersions were separated, washed, centrifuged and stored at room temperature. Picloram (PCM) herbicide interaction with surface groups of montmorillonite (Mt) was studied using XRD, DTA, FTIR and XPS techniques. The entrance of PCM into the Mt basal space, in two different arrangements, perpendicular and planar, is proposed and the final arrangement depends on PCM concentration. The interaction of PCM with Mt surface sites through the nitrogen of the pyridine ring and carboxylic group of PCM, forming bidentate and bridge inner-sphere complexes was confirmed by FTIR and XPS analysis. The acidity constant of the PCM adsorbed on the Mt surface was calculated. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Surface complexation modeling of Cd(II) sorption to montmorillonite, bacteria, and their composite

    Science.gov (United States)

    Wang, Ning; Du, Huihui; Huang, Qiaoyun; Cai, Peng; Rong, Xingmin; Feng, Xionghan; Chen, Wenli

    2016-10-01

    Surface complexation modeling (SCM) has emerged as a powerful tool for simulating heavy metal adsorption processes on the surface of soil solid components under different geochemical conditions. The component additivity (CA) approach is one of the strategies that have been widely used in multicomponent systems. In this study, potentiometric titration, isothermal adsorption, zeta potential measurement, and extended X-ray absorption fine-structure (EXAFS) spectra analysis were conducted to investigate Cd adsorption on 2 : 1 clay mineral montmorillonite, on Gram-positive bacteria Bacillus subtilis, and their mineral-organic composite. We developed constant capacitance models of Cd adsorption on montmorillonite, bacterial cells, and mineral-organic composite. The adsorption behavior of Cd on the surface of the composite was well explained by CA-SCM. Some deviations were observed from the model simulations at pH SCM closely coincided with the estimated value of EXAFS at pH 6. The model could be useful for the prediction of heavy metal distribution at the interface of multicomponents and their risk evaluation in soils and associated environments.

  2. Characterization of hybrid microparticles/Montmorillonite composite with raspberry-like morphology for Atorvastatin controlled release.

    Science.gov (United States)

    García-Guzmán, Perla; Medina-Torres, Luis; Calderas, Fausto; Bernad-Bernad, María Josefa; Gracia-Mora, Jesús; Mena, Baltasar; Manero, Octavio

    2018-07-01

    In this work, we prepared a novel composite based on hybrid gelatin carriers and montmorillonite clay (MMT) to analyze its viability as controlled drug delivery system. The objective of this research involves the characterization of composites formed by structured lipid-gelatin micro-particles (MP) and MMT clay. This analysis included the evaluation of the composite according to its rheological properties, morphology (SEM), particle size, XRD, FT-IR, and in vitro drug release. The effect of pH in the properties of the composite is evaluated. A novel raspberry-like or armor MP/MMT clay composite is reported, in which the pH has an important effect on the final structure of the composite for ad-hoc drug delivery systems. For pH values below the isoelectric point, we obtained defined morphologies with entrapment efficiencies up to 67%. The pH level controls the MP/MMT composite release mechanism, restringing drug release in the stomach-like environment. Intended for oral administration, these results evidence that the MP/MMT composite represents an attractive alternative for intestinal-colonic controlled drug delivery systems. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Aldehyde-functionalized chitosan-montmorillonite films as dynamically-assembled, switchable-chemical release bioplastics.

    Science.gov (United States)

    Chabbi, Jamal; Jennah, Oumayma; Katir, Nadia; Lahcini, Mohamed; Bousmina, Mosto; El Kadib, Abdelkrim

    2018-03-01

    Temporal release of synergistic and/or complementary chemicals (e.g.: drugs) is recognized as extremely challenging because of their frequently intertwined kinetic delivery and presently, straightforward concepts enabling to circumvent this bottleneck are missing in the open literature. In this framework, we report herein on aldehyde-functionalized, transparent and flexible chitosan-montmorillonite hybrid films that act as a new generation of eco-friendly, controlled-chemical release bioplastics. These dynamically-assembled nanomaterials are designed by a ternary assembly from biowaste derived chitin biopolymer, aromatic aldehydes and layered clay nanoparticles. On the basis of their geometrical and conformational properties, the oxygenated groups on the grafted aromatics interact preferentially with either the base Schiff belonging to the carbohydrate (via intramolecular CNHO-Ar known as "imine clip") or with the hydroxyl groups belonging to the clay surface (via intermolecular Si-OHO-Ar). The exfoliated clay nanoparticles within the carbohydrate polymer enables either accelerating or slowing down of the imine (CN) hydrolysis depending on the interaction of the conjugated aromatics. This provides the driving force for fine tuning host-guest interactions at the molecular level and constitutes an entry toward subtle discrimination of different chemicals (e.g. complementary fertilizers, synergistic drugs) during their sequential release. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Montmorillonite-lipid hybrid carriers for ionizable and neutral poorly water-soluble drugs: Formulation, characterization and in vitro lipolysis studies.

    Science.gov (United States)

    Dening, Tahnee J; Rao, Shasha; Thomas, Nicky; Prestidge, Clive A

    2017-06-30

    Lipid-based formulations (LBFs) are a popular strategy for enhancing the gastrointestinal solubilization and absorption of poorly water-soluble drugs. In light of this, montmorillonite-lipid hybrid (MLH) particles, composed of medium-chain triglycerides, lecithin and montmorillonite clay platelets, have been developed as a novel solid-state LBF. Owing to the unique charge properties of montmorillonite, whereby the clay platelet surfaces carry a permanent negative charge and the platelet edges carry a pH-dependent charge, three model poorly water-soluble drugs with different charge properties; blonanserin (weak base, pKa 7.7), ibuprofen (weak acid, pKa 4.5) and fenofibrate (neutral), were formulated as MLH particles and their performance during biorelevant in vitro lipolysis at pH 7.5 was investigated. For blonanserin, drug solubilization during in vitro lipolysis was significantly reduced 3.4-fold and 3.2-fold for MLH particles in comparison to a control lipid solution and silica-lipid hybrid (SLH) particles, respectively. It was hypothesized that strong electrostatic interactions between the anionic montmorillonite platelet surfaces and cationic blonanserin molecules were responsible for the inferior performance of MLH particles. In contrast, no significant influence on drug solubilization was observed for ibuprofen- and fenofibrate-loaded MLH particles. The results of the current study indicate that whilst MLH particles are a promising novel formulation strategy for poorly water-soluble drugs, drug ionization tendency and the potential for drug-clay interactions must be taken into consideration to ensure an appropriate performance. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Characterization of bentonite clay from “Greda” deposit

    Directory of Open Access Journals (Sweden)

    Nadežda Stanković

    2011-06-01

    Full Text Available Based on mineralogical and technological investigations of the deposit “Greda” important characteristics of bentonite clay were determined. Representative samples of the deposit were characterized with X-ray diffraction, low-temperature nitrogen adsorption, chemical analysis, differential thermal analysis and scanning electron microscopy. It was determined that the main mineral is montmorillonite and in subordinate quantities kaolinite, quartz and pyrite. The chemical composition generally shows high silica and alumina contents in all samples and small quantities of Fe3+, Ca2+ and Mg2+ cations. Based on technological and mineralogical research, bentonite from this deposit is a high-quality raw material for use in the ceramic industry.

  6. Extraction of selected heavy metals using modified clays.

    Science.gov (United States)

    Krikorian, Nadine; Martin, Dean F

    2005-01-01

    In the present study, attapulgite, kaolinite, and montmorillonite KSF were modified using azeotropic distillation to condense 2-mercaptoethanol with the clay material. The resulting product was used as a coordinating agent to remove selected metal ions, e.g., copper(II), cadmium(II), silver(I), nickel(II), and lead(II) ions from standard aqueous solutions. Batch systems were used, and samples were shaken for two hours, and following filtration, metal content of the filtrate was measured by atomic absorption spectrometry. Without adjusting the pH, better than 90% of the metal ions could be removed.

  7. Clay mineral facies and lateritization in basalts of the southeastern Parana Basin, Brazil

    International Nuclear Information System (INIS)

    Oliveira, M.T.G. de; Formoso, M.L.L.; Trescases, J.J.; Meunier, A.

    1998-01-01

    Seventeen samples from two lateritic profiles, each with five facies, were studied. These profiles occur on the old planation surface of the plateau basalts of the southern part of ParanáBasin, Brazil. Optical microscopy, X-ray diffraction, electron microprobe, Mössbauer spectroscopy and Fourier Transform Infrared Spectra were used to obtain information about the nature and chemical composition of each weathering facies. In addition, scanning electron microscopy and analyses of clay minerals were performed to detect microcrystalline environmental changes. Both profiles have two major parts: a loose red-clay latosol separated from an underlying mottled clay and an alterite facies; a stone line may or may not be present between the latosol and the underlying units. In both profiles the latosol consists principally of kaolinite, hematite and goethite. Two alterite facies, shaped by differential weathering, are also present in the lower profile: a halloysite–nontronite clayey matrix with a well developed fissure system occurs in the argillaceous alterite and a network of Al–goethite aggregates is typical of the highly porous cortex of the boulder alterite that is found in the stone line and below it. Gibbsite has crystallized in the large pores of porphyritic boulder alterite but is absent in the small pores of the subaphyric boulder alterite. Clay minerals observed in fissures include halloysite associated with goethite and manganese oxides. The basalt has hydrothermal green-clays (mixed layers and trioctahedral smectites) that formed between primary plagioclase, pyroxene and Ti–magnetite crystals while fresh corestones of the boulder alterite have cryptocrystalline iron-rich material. The study of these profiles shows one principal evolutionary trend for clay minerals. This trend is from smectite and mixed layers that form green clays in altered bedrock at the base of the profile to an intermediate association of nontronite and halloysite in the argillaceous

  8. Self-Assembly of Alkylammonium Chains on Montmorillonite: Effect of Interlayer Cations, CEC, and Chain Length

    Science.gov (United States)

    Chen, Hua; Li, Yingjun; Zhou, Yuanlin; Wang, Shanqiang; Zheng, Jian; He, Jiacai

    2017-12-01

    Recently, polymeric materials have been filled with synthetic or natural inorganic compounds in order to improve their properties. Especially, polymer clay nanocomposites have attracted both academic and industrial attention. Currently, the structure and physical phenomena of organoclays at molecular level are difficultly explained by existing experimental techniques. In this work, molecular dynamics (MD) simulation was executed using the CLAYFF and CHARMM force fields to evaluate the structural properties of organoclay such as basal spacing, interlayer density, energy and the arrangement of alkyl chains in the interlayer spacing. Our results are in good agreement with available experimental or other simulation data. The effects of interlayer cations (Na+, K+, Ca2+), the cation exchange capacity, and the alkyl chain length on the basal spacing and the structural properties are estimated. These simulations are expected to presage the microstructure of organo-montmorillonite and lead relevant engineering applications.

  9. Application of Modified Nanonaturally Montmorillonite in Monochlorobenzene Remediation in River Water

    Science.gov (United States)

    Liu, Chen; Chen, Jun-Feng; Li, Yun; Chen, Rong-Chang; Asaoka, Sachio; Yuan, Guo-Li

    2012-12-01

    As the inland waterway transportation developed rapidly in China, the frequency of hazardous chemical leakage accidents is increasing every year. Such pollution to inland river environment has become a world-wide issue. Montmorillonite (Mont) is typical 2:1 layer type silicate clay and due to their special structure, it has been used in organic pollution removal process. In order to improve their ability in pollution adsorption, the pillared Mont was made in this work. Since the common toxic structure in most chemical pollutants is the halogen atom-benzene ring part, we select a typical compound Monochlorobenzene (MCB) as the aim contaminant. In this research, the original Mont, Na-Mont, TiO2 and TiO2-Mont were prepared and used in MCB degradation experiment as catalysts. The influence of catalyst amount, promoter (H2O2) amount, MCB concentration and reaction time to MCB removal rate were studied, respectively in detail.

  10. Adsorption behavior of strontium on binary mineral mixtures of Montmorillonite and Kaolinite

    Energy Technology Data Exchange (ETDEWEB)

    Bascetin, Elvan [Cekmece Nuclear Research and Training Center, P.K.1 34149, Atatuerk Airport, Istanbul (Turkey); Atun, Guelten [Engineering Faculty, Chemistry Department, Istanbul University, 34850 Avcilar, Istanbul (Turkey)]. E-mail: gultena@istanbul.edu.tr

    2006-08-15

    The adsorption behavior of kaolinite and montmorillonite minerals and their mixtures in respect of Sr ion were studied by means of a batch method using {sup 90}Sr as a radio tracer. The effect of several parameters such as temperature, pH, Sr concentration and supporting electrolyte were investigated. Experimentally measured distribution coefficients showed a good agreement to within 98.5-99.7% with theoretically calculated values. The values of adsorption capacity of adsorbents and mean adsorption energy of adsorption were calculated by fitting the adsorption data to Dubinin-Radushkevich isotherm. The adsorption capacity of clay mixtures decreased as kaolinite fractions increased. The mean adsorption energy values of 8.0-9.5 kJ mol{sup -1} showed that adsorption was governed by ion exchange. The Freundlich parameters were used to characterize a site distribution function for binary exchange between Sr and Na.

  11. Adsorption behavior of strontium on binary mineral mixtures of Montmorillonite and Kaolinite

    International Nuclear Information System (INIS)

    Bascetin, Elvan; Atun, Guelten

    2006-01-01

    The adsorption behavior of kaolinite and montmorillonite minerals and their mixtures in respect of Sr ion were studied by means of a batch method using 90 Sr as a radio tracer. The effect of several parameters such as temperature, pH, Sr concentration and supporting electrolyte were investigated. Experimentally measured distribution coefficients showed a good agreement to within 98.5-99.7% with theoretically calculated values. The values of adsorption capacity of adsorbents and mean adsorption energy of adsorption were calculated by fitting the adsorption data to Dubinin-Radushkevich isotherm. The adsorption capacity of clay mixtures decreased as kaolinite fractions increased. The mean adsorption energy values of 8.0-9.5 kJ mol -1 showed that adsorption was governed by ion exchange. The Freundlich parameters were used to characterize a site distribution function for binary exchange between Sr and Na

  12. Study of relaxation times of nanocomposites of starch/montmorillonite employing low field NMR

    International Nuclear Information System (INIS)

    Brito, Luciana M.; Tavares, Maria Ines B.

    2011-01-01

    Due to its various applications and features, especially in therapies for controlled release of pharmaceuticals, polymers are among the most widely used excipients in pharmaceutical technology. One of the most promising nanocomposites is formed from organic polymer and inorganic clay minerals. Nanocomposites of starch/montmorillonite were prepared employing solution intercalation and characterized by proton spin-lattice relaxation time, through NMR relaxometry. The characterization of nanocomposites was done by X-ray diffraction and by nuclear magnetic resonance. The results showed that nanostructured films were obtained by intercalation from solution. Furthermore, the use of low field NMR, T1H, provided more precise information about the movement of materials, being complementary to the results obtained by X-ray diffraction. (author)

  13. Obtention of polyester-montmorillonite (MMT) nanocomposites applied to powder coating - part 1: nanocomposites characterization

    International Nuclear Information System (INIS)

    Piazza, Diego; Zattera, Ademir J.; Silveira, Debora S.; Lorandi, Natalia P.; Birriel, Eliena J.; Scienza, Lisete C.

    2009-01-01

    The development and obtention of polymeric nanocomposites in the nanotechnology and nanoscience field have attracted great attention due to diversity of potential applications and significant property improvement when compared to conventional composites. In this work, commercial formulations of polyester-based powder coating with 0, 2 and 4% (w/w) of montmorillonite (MMT) were obtained by incorporation in the melting state and characterized by TEM, SEM, DSC, TGA and XRD. The nanocoatings were applied on the mild carbon steel panels by electrostatic paint. The microscopy analysis showed MMT in the coating film, predominantly in the exfoliated form, corroborated by XRD results. Some tactoid structures and a surface film with some defects and porous were also revealed. Progressive reduction of crosslinking temperature and thermal stability was observed in thermal analysis. The best clay dispersion in the coating and a higher quality film were achieved at 2% MMT concentration. (author)

  14. Linking the Diffusion of Water in Compacted Clays at Two Different Time Scales: Tracer Through-Diffusion and QENS

    International Nuclear Information System (INIS)

    Juranyi, Fanni; Gonzalez Sanchez, Fatima; Gimmi, Thomas; Bestel, Martina; Van Loon, Luc; Diamond, Larryn W.

    2013-01-01

    Observable water diffusion processes in clays and their parameters depend on the spatial- and time-scale of the measurement. Comparing the diffusion coefficients of quasielastic neutron scattering and tracer through-diffusion, 'chemical' and 'geometrical' effects can be distinguished and quantified. Results for montmorillonite and illite in the Na- and Ca- form illustrate this very well. Swelling clays such as montmorillonite are especially interesting because of the interlayer water. This water is confined in form of few layers such that the diffusion occurs essentially in 2D. Furthermore the ratio of interlayer- and external- (macro-pore) water changes as a function of bulk dry density and degree of water saturation. Therefore it is of interest to describe the diffusion process using these parameters. Finally, the activation energy of the diffusion should be equal for both methods assuming that the geometrical factor does not depend on temperature. For the montmorillonites this was not the case, which might also indicate that the main processes on the two scales are different. We conclude that the geometrical factor and the electrostatic constraint can be determined from a comparison of the diffusion coefficients measured by the two different techniques: quasielastic neutron scattering and tracer through diffusion. Furthermore, activation energies obtained at the two scales are similar for clays having no interlayer water. For montmorillonite the activation energy values are different. Further investigations are required to clarify the reason. (authors)

  15. Selective removal and inactivation of bacteria by nanoparticle composites prepared by surface modification of montmorillonite with quaternary ammonium compounds.

    Science.gov (United States)

    Khalil, Rowaida K S

    2013-10-01

    The purpose of the present study was to prepare new nanocomposites with antibacterial activities by surface modification of montmorillonite using quaternary ammonium compounds that are widely applied as disinfectants and antiseptics in food-processing environments. The intercalation of four quaternary ammonium compounds namely benzalkonium chloride, cetylpyridinium chloride monohydrate, hexadecyltrimethylammonium bromide, tetraethylammonium chloride hydrate into montmorillonite layers was confirmed by X-ray diffraction. The antibacterial influences of the modified clay variants against important foodborne pathogens differed based on modifiers quantities, microbial cell densities, and length of contact. Elution experiments through 0.1 g of the studied montmorillonite variants indicated that Staphylococcus aureus, Pseudomonas aeroginosa, and Listeria monocytogenes were the most sensitive strains. 1 g of hexadecyltrimethylammonium bromide intercalated montmorillonites demonstrated maximum inactivation of L. monocytogenes populations, with 4.5 log c.f.u./ml units of reduction. In adsorption experiments, 0.1 g of tetraethylammonium chloride hydrate montmorillonite variants significantly reduced the growth of Escherichia coli O157:H7, L. monocytogenes, and S. aureus populations by 5.77, 6.33, and 7.38 log units respectively. Growth of wide variety of microorganisms was strongly inhibited to undetectable levels (benzalkonium chloride montmorillonite variants. This investigation highlights that reduction in counts of microbial populations adsorbed to the new nanocomposites was substantially different from that in elution experiments, where interactions of nanocomposites with bacteria were specific and more complex than simple ability to inactivate. Treatment columns packed with modified variants maintained their inactivation capacity to the growth of Salmonella Tennessee and S. aureus populations after 48 h of incubation at room temperature with maximum reductions

  16. Influence of compatibilizer and/or montmorillonite addition on the mechanical properties and morphology of PP/recycled PET blends

    International Nuclear Information System (INIS)

    Silva, Murilo S.; Souza, Adriana M.C.

    2011-01-01

    In this work, the mechanical properties and morphology PP/recycled PET blends with addition of P(E-co-MA-co-GMA) copolymer and/or montmorillonite clay (MMT) was investigated. The blends were obtained by extrusion and their morphology was observed by scanning electron microscopy. The mechanical properties were evaluated by tensile and impact tests. Thin films of nanocomposites were characterized by x-ray diffraction (XRD). The addition of P (E-co-MA-co-GMA) or MMT clay separately promoted a decrease of the dispersed phase size. XRD analysis indicated that there was incorporation of polymer in clay galleries. The addition of clay in PP / PET blend resulted in an increase of apparent elastic modulus, impact resistance and HDT and a decrease of tensile strength and elongation at break. The addition of P (E-co-MA-co-GMA) resulted in an increased impact strength and reduction of other properties. There were no significant changes on mechanical properties when the clay and P (E-co-MA-co-GMA) are added simultaneously. (author)

  17. Synthesis and characterization of nanohybrid of montmorillonite and zinc oxide

    International Nuclear Information System (INIS)

    Chagas, Beatriz S.; Mendes, Luis C.; Brito, Alice S.

    2009-01-01

    Zinc oxide-aluminosilicate nanohybrids through a hydrothermal reaction of a colloidal suspension of exfoliated montmorillonite nanosheets and zinc oxide in acid solution, performed in three different routes, were synthesized. The products were characterized by wide angle X-ray diffraction (WAXD). In all routes, it was found that the intercalation of zinc oxide into the host montmorillonite gallery was successfully performed so that the crystalline peaks of the montmorillonite and zinc oxide were suppressed from the X-ray patterns. The use of ultrasound decreased the reaction time.(author)

  18. Pb sorption on montmorillonite-bacteria composites: A combination study by XAFS, ITC and SCM.

    Science.gov (United States)

    Qu, Chenchen; Du, Huihui; Ma, Mingkai; Chen, Wenli; Cai, Peng; Huang, Qiaoyun

    2018-06-01

    Though abundant studies have targeted the characterization of heavy metal adsorption by either clay minerals or bacteria, to date, minimal literature exists which specifically assesses bacteria-clay mineral interactions in the context of metal immobilization. The adsorption of Pb onto montmorillonite, Pseudomonas putida, and their 1:1, 2:1, 6:1 and 12:1 mass ratio composites were investigated by using a combination of atomic force microscope (AFM), X-ray diffraction (XRD), surface complexation modeling (SCM), Pb-L III edge extended X-ray absorption fine structure (EXAFS) spectroscopy and isothermal titration calorimetry (ITC). The SCM and EXAFS demonstrated that Pb ions coordinate with phosphoryl and carboxyl functional groups on bacteria at low and high concentrations, respectively. The ITC analysis found adverse enthalpy values for Pb adsorption to permanent (-2.91 kJ/mol) and variable charge sites (6.93 kJ/mol) on montmorillonite. The ternary bridging model, EXAFS and ITC provide molecular and thermodynamic evidences for the formation of enthalpy driven (-4.74 kJ/mol) ternary complex (>AlO-Pb-PO 4 ) in the composites. The proportion for the bridging structures increased at pH > 5 and high bacterial mass ratios. The formation of ternary complex did not result in the enhanced adsorption of Pb on the composites, but promoted the allocation of Pb on the mineral fraction. The results obtained from SCM, EXAFS and ITC may provide an essential assumption for predicting the speciation and fate of Pb in soils and associated environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. A quantitative mechanistic description of Ni, Zn and Ca sorption on Na-Montmorillonite. Part I: Physico-chemical characterisation and titration measurements

    International Nuclear Information System (INIS)

    Baeyens, B.; Bradbury, M.H.

    1995-07-01

    The work presented in this report is primarily concerned with characterisation studies and titration measurements on conditioned Na-montmorillonite. The starting material, SWy-1 Na-montmorillonite (Crook County, Wyoming, USA), contains background metal impurities, soluble salts and sparingly soluble minerals which can influence titration and sorption measurements and thereby lead to difficulties in the interpretation of the data. A conditioning procedure is described which yielded a purified clay material in the homoionic sodium form with a particle size 4 . The reasons for choosing a batch method, coupled with back titration of the supernatant solutions, instead of a continuous procedure, are fully discussed. Chemical analyses data for the supernatant solutions are presented in detail. The influence of background impurities, not removed by the conditioning, and cation exchange processes on the form of the titration curves were investigates. Net Na-montmorillonite titration curves at two different ionic strengths were derived which are considered to reflect only the acid/base behaviour of ≡SOH type surface sites. The acid end point in the titration data was used to estimate an ≡SOH site capacity of 0.08 moles per kg conditioned Na-montmorillonite. (author) 8 figs., 19 tabs., refs

  20. Characterization of Lin'an montmorillonite and its application in the removal of Ni{sup 2+} from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Tan, X.L.; Hu, J.; Zhou, X.; Wang, X.K. [Inst. of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Yu, S.M. [School of Chemical Engineering, Hefei Univ. of Tech., Hefei (China)

    2008-07-01

    Clay minerals have been studied extensively because of their strong sorption and complexation ability. In this work, Na-montmorillonite was characterized by using acid-base titration, XRD and FTIR in detail. Sorption of Ni(II) on Na-montmorillonite was investigated under ambient conditions as a function of pH, ionic strength, and temperature. The results indicate that sorption of Ni{sup 2+} on montmorillonite are strongly dependent on pH and ionic strength. The sorption of Ni{sup 2+} is mainly dominated by ion exchange at low pH values and by inner-sphere surface complexation at high pH values. The relationships of pH-C{sub eq}, Q-C{sub eq} and pH-Q are compared and shown clearly in a 3-D plot, and all Q-C{sub eq} data lie in a straight line with slope (- V/m) and intercept (C{sub 0}V/m). The thermodynamic parameters ({delta}H , {delta}S , and {delta}G ) are calculated from the temperature dependent sorption isotherms, and the results suggest that the sorption reaction of Ni(II) from solution to montmorillonite is endothermic and spontaneous. (orig.)

  1. Salinity Effects on the Adsorption of Nucleic Acid Compounds on Na-Montmorillonite: a Prebiotic Chemistry Experiment

    Science.gov (United States)

    Villafañe-Barajas, Saúl A.; Baú, João Paulo T.; Colín-García, María; Negrón-Mendoza, Alicia; Heredia-Barbero, Alejandro; Pi-Puig, Teresa; Zaia, Dimas A. M.

    2018-02-01

    Any proposed model of Earth's primitive environments requires a combination of geochemical variables. Many experiments are prepared in aqueous solutions and in the presence of minerals. However, most sorption experiments are performed in distilled water, and just a few in seawater analogues, mostly inconsistent with a representative primitive ocean model. Therefore, it is necessary to perform experiments that consider the composition and concentration of dissolved salts in the early ocean to understand how these variables could have affected the absorption of organic molecules into minerals. In this work, the adsorption of adenine, adenosine, and 5'AMP onto Na+montmorillonite was studied using a primitive ocean analog (4.0 Ga) from experimental and computational approaches. The order of sorption of the molecules was: 5'AMP > adenine > adenosine. Infrared spectra showed that the interaction between these molecules and montmorillonite occurs through the NH2 group. In addition, electrostatic interaction between negatively charged montmorillonite and positively charge N1 of these molecules could occur. Results indicate that dissolved salts affect the sorption in all cases; the size and structure of each organic molecule influence the amount sorbed. Specifically, the X-ray diffraction patterns show that dissolved salts occupy the interlayer space in Na-montmorillonite and compete with organic molecules for available sites. The adsorption capacity is clearly affected by dissolved salts in thermodynamic terms as deduced by isotherm models. Indeed, molecular dynamic models suggest that salts are absorbed in the interlamellar space and can interact with oxygen atoms exposed in the edges of clay or in its surface, reducing the sorption of the organic molecules. This research shows that the sorption process could be affected by high concentration of salts, since ions and organic molecules may compete for available sites on inorganic surfaces. Salt concentration in primitive

  2. Radiation damage study in montmorillonites. Application to the high-level nuclear waste disposal in France

    International Nuclear Information System (INIS)

    Sorieul, St.

    2003-11-01

    Smectite is a major component of bentonite, a material considered for engineered barriers in high level nuclear wastes repositories (HLNWR). In order to predict the long-term performance of the bentonite, various physical and chemical factors such as, e.g., thermal gradient, redox potential or mechanical stresses are currently considered. By contrast, little is known about radiation effects in smectite, although it might affect the properties of this mineral through cumulative radiation damages produced by ionizing radiations. The present study focuses on radiation damage in montmorillonite considered herein as a simplified model of bentonite. Two reference clays have been selected, one from Liaoning (China, CHI), containing native radiation-induced defects, and the other (called MX) separated from the MX80 reference bentonite (Wyoming, USA). They are distinguished by layer composition, particularly iron content (1 % and 4 % for CHI and MX, respectively). Radiation effects have been studied by combining X-ray diffraction, Fourier transform infrared spectroscopy, Electron Paramagnetic Resonance (EPR) and Moessbauer spectroscopies. Ionizing irradiation induces two main effects. First, several paramagnetic point defects are identified as trapped holes located on oxygen atoms of the smectite structure. These defects are characterized by different thermal stabilities, according to annealing experiments. Their creation is limited by saturation curve with maximum damage around 100 MGy. The response of the two montmorillonites is different in terms of nature and production of point defects, indicating a role of layer composition and structural precursors. Besides, EPR and Moessbauer results show substantial modifications of the oxidation state of structural iron, which are sample and dose-dependent. Irradiation induces reduction and oxidation of iron in CHI and MX samples, respectively. Moreover, physico-chemical treatments show that intensity of redox effects varies

  3. Model for Anomalous Moisture Diffusion through a Polymer-Clay Nanocomposite

    DEFF Research Database (Denmark)

    Drozdov, Aleksey D.; Christiansen, Jesper de Claville; Gupta, R.K.

    2003-01-01

    Experimental data are reported on moisture diffusion and the elastoplastic response of an intercalated nanocomposite with vinyl ester resin matrix and montmorillonite clay filler at room temperature. Observations in diffusion tests showed that water transport in the neat resin is Fickian, whereas...... platelets. Constitutive equations are developed for moisture diffusion through and the elastoplastic behavior of a nanocomposite. Adjustable parameters in these relations are found by fitting the experimental data. Fair agreement is demonstrated between the observations and the results of numerical...

  4. A model for anomalous moisture diffusion through a polymer-clay nanocomposite

    DEFF Research Database (Denmark)

    Drozdov, Aleksey D.; Christiansen, Jesper de Claville; Gupta, R.K.

    2002-01-01

    Experimental data are reported on moisture diffusion and the elastoplastic response in uniaxial tensile tests of an intercalated nanocomposite with vinyl ester resin matrix and montmorillonite clay filler at room temperature. Observations in diffusion tests show that the moisture transport...... diffusion through a nanocomposite and for its elastoplastic behavior. Adjustable parameters in these relations are found by fitting the experimental data. Fair agreement is demonstrated between the observations and the results of numerical simulation....

  5. Polymer Nanocomposites—A Comparison between Carbon Nanotubes, Graphene, and Clay as Nanofillers

    Science.gov (United States)

    Bhattacharya, Mrinal

    2016-01-01

    Nanofilled polymeric matrices have demonstrated remarkable mechanical, electrical, and thermal properties. In this article we review the processing of carbon nanotube, graphene, and clay montmorillonite platelet as potential nanofillers to form nanocomposites. The various functionalization techniques of modifying the nanofillers to enable interaction with polymers are summarized. The importance of filler dispersion in the polymeric matrix is highlighted. Finally, the challenges and future outlook for nanofilled polymeric composites are presented. PMID:28773388

  6. The use of synthetic Zn-/Ni-labeled montmorillonite colloids as a natural bentonite marker

    International Nuclear Information System (INIS)

    Huber, F.; Heck, S.; Hoess, P.; Bouby, M.; Schaefer, T.; Truche, L.; Brendle, J.

    2012-01-01

    Document available in extended abstract form only. Quantification of bentonite erosion rates/colloid release rates and the colloid attachment under unfavourable conditions for clay colloids is frequently based on the detection of the alumino-silicate building blocks and accompanied by relative high analytical uncertainties due to the presence of high background concentrations in the groundwater. In situ experiments planned at the Grimsel Test Site (CH) in the frame of the Colloid Formation and Migration (CFM) project foresee the emplacement of a compacted bentonite source and determination of the bentonite erosion rate under near-natural flow conditions. To univocally differentiate between the natural background colloid concentration and the eroded bentonite an irreversible labeling of the bentonite colloid source placed in a granite fracture would greatly improve their detection and reduce the analytical uncertainty. It is thought to use an admixture to label the natural bentonite. Therefore, the characteristics as erosion behavior, colloid stability and radionuclide sorption/reversibility behavior have to be studied and compared. Here, we focus on the radionuclide sorption reversibility. Synthetic montmorillonite containing structurally bound Zn and Ni in its octahedral layer was used within this study. Actually, Zn and Ni are good candidates to determine more accurately the colloid concentration as the ICP-MS sensitivity is at least one order of magnitude higher and the Zn and Ni background concentrations found in natural ground waters (e.g. Grimsel ground water, GGW) are very low. In the present study, the colloids are first separated and characterized by AsFlFFF-ICP-MS. Then, they are used to perform radionuclide reversibility kinetic experiments similar to those already published under anoxic conditions and room temperature. The aim is to compare the results obtained with those already available on natural FEBEX bentonite derived colloids. The size

  7. Caffeine adsorption of montmorillonite in coffee extracts.

    Science.gov (United States)

    Shiono, Takashi; Yamamoto, Kenichiro; Yotsumoto, Yuko; Yoshida, Aruto

    2017-08-01

    The growth in health-conscious consumers continues to drive the demand for a wide variety of decaffeinated beverages. We previously developed a new technology using montmorillonite (MMT) in selective decaffeination of tea extract. This study evaluated and compared decaffeination of coffee extract using MMT and activated carbon (AC). MMT adsorbed caffeine without significant adsorption of caffeoylquinic acids (CQAs), feruloylquinic acids (FQAs), dicaffeoylquinic acids (di-CQAs), or caffeoylquinic lactones (CQLs). AC adsorbed caffeine, chlorogenic acids (CGAs) and CQLs simultaneously. The results suggested that the adsorption selectivity for caffeine in coffee extract is higher in MMT than AC. The caffeine adsorption isotherms of MMT in coffee extract fitted well to the Langmuir adsorption model. The adsorption properties in coffee extracts from the same species were comparable, regardless of roasting level and locality of growth. Our findings suggest that MMT is a useful adsorbent in the decaffeination of a wide range of coffee extracts.

  8. Dehydration kinetics of a natural montmorillonite

    International Nuclear Information System (INIS)

    Andreotti, G.; Loria, A.; Mazzega, E.; Valeri, S.

    1978-01-01

    The dehydration mass loss of samples of montmorillonite (a layered hydrated silicate) was measured in an environment at constant temperature and at constant undersatured water vapour content. The hydration curves were analyzed by assuming the model of thermally activated, monoenergetic and first-order process compatible with the experimental results. Two dehydration kinetics with activation energies (0.21+-0.02) eV and (0.34+-0.02) eV were found that can be related to the existence of two kinds of water (structured and nonstructured) in the hydrated silicate interlayers. The possibility of an icelike structure of a fraction of the adsorbed molecules is briefly discussed. The experimental results show, furthermore, that in the investigated hydration range (up to about 10% in mass) the fraction of structured water has a maximum when the hydration is about 6%. (author)

  9. Effects of Applying Lime and CalciumMontmorillonite on Nitrification Dynamics in Acidic Soil

    Directory of Open Access Journals (Sweden)

    WANG Mei

    2017-01-01

    Full Text Available Soil acidification is known as a natural and slow process along with clay mineral weathering. In recent years however, with inten sive soil utilization in agriculture, soil acidification has increased dramatically and nitrification of ammonium nitrogen fertilizer is one of the main contributors to soil acidification. Lime application is the traditional practice to improve acidic soils but it often makes the soil acidic a gain leading to soil compaction in most cases. Montmorillonite is the main clay mineral component of alkaline or neutral soils, more so it is known to undergo further weathering processes during soil acidification. The laboratory-based incubations were used in this study, and nitri fication was measured while kinetic curves were fitted to check the effects of decreasing soil acidity by lime(Ca-OHand montmorillonite (Ca-Mon nitrification of the acidic soil. The results showed that significant nitrification was observed both in Ca-OH and Ca-M treatments, and the nitrification process was fitted in the first-order kinetic model, NNO3=N0+Np(1-exp(-k1t(P-1·d-1was significantly higher than that of Ca-M treatment(2.381 mg·kg-1·d-1. The potential nitrifi cation rate(Vpwere 6.42, 8.58 mg N·kg-1·d-1 at pH 5.7 and 6.2 respectively, and the average nitrification rate(Vaof Ca-OH treatment were 2.71, 3.88 mg N·kg-1·d-1 respectively, which were significantly greater than those of Ca-M treatment(Vp were 3.40, 4.56 mg N·kg-1·d-1 and Va were 2.36, 3.04 mg N·kg-1·d-1 at pH 5.7 and 6.2 respectively. Therefore the net nitrification rate, potential nitrification rate(Vp and average nitrification rate(Vaof Ca-OH treatment were significantly higher than that of Ca-M treatment, suggesting that the possibili ty and degree of soil reacidification by using lime to improve acidic soil is greater than using calcium montmorillonite. This study will provide a new reference for the improvement of acid soils.

  10. Sorption of tetracycline on organo-montmorillonites

    International Nuclear Information System (INIS)

    Liu, Niu; Wang, Ming-xia; Liu, Ming-ming; Liu, Fan; Weng, Liping; Koopal, Luuk K.; Tan, Wen-feng

    2012-01-01

    Highlights: ► The sorption capacity of tetracycline on Mont. modified with QACs was highly promoted. ► Tetracycline adsorbed on organoclay was affected by the amount and the length of QACs. ► Tetracycline adsorption on organoclay exhibited high pH-dependence below 5. - Abstract: Tetracycline (TC) is a veterinary antibiotic that is frequently detected as pollutant in the environment. Powerful adsorbents are required for removing TC. The present paper compares the TC adsorption capacity of Na-montmorillonite (Na-mont) with six organo-montmorillonites (organo-monts). Three quaternary ammonium cations (QACs) with different alkyl-chain lengths were used as modifiers. Powder X-ray diffraction indicated that the d 001 values of organo-monts increased with increasing the QACs loading and alkyl-chain length. The CECs of the organo-monts were substantially lower than that of Na-mont and decreased with QACs chain length and increased loading. The modeling of the adsorption kinetics revealed that the processes of TC adsorption on the tested samples could be well fitted by the pseudo-second-order equation. The maximum adsorption capacities of TC on the organo-monts (1000–2000 mmol/kg) were considerably higher than that on Na-mont (769 mmol/kg). Both the Langmuir and Freundlich model could fit the adsorption isotherms. The TC adsorption to the organo-monts increase significantly with decreasing the pH below 5.5 because of the electrostatic interaction, and a high QACs loading performed better than a low loading at around pH 3.

  11. Smectite clays in Mars soil - Evidence for their presence and role in Viking biology experimental results

    Science.gov (United States)

    Banin, A.; Rishpon, J.

    1979-01-01

    Evidence for the presence of smectite clays in Martian soils is reviewed and results of experiments with certain active clays simulating the Viking biology experiments are reported. Analyses of Martian soil composition by means of X-ray fluorescence spectrometry and dust storm spectroscopy and Martian geological history strongly suggest the presence of a mixture of weathered ferro-silicate minerals, mainly nontronite and montmorillonite, accompanied by soluble sulphate salts, as major constituents. Samples of montmorillonite and nontronite incubated with (C-14)-formate or the radioactive nutrient medium solution used in the Viking Labeled Release experiment, were found to produce patterns of release of radioactive gas very similar to those observed in the Viking experiments, indicating the iron-catalyzed decomposition of formate as the reaction responsible for the Viking results. The experimental results of Hubbard (1979) simulating the results of the Viking Pyrolytic Release experiment using iron montmorillonites are pointed out, and it is concluded that many of the results of the Viking biology experiments can be explained in terms of the surface activity of smectite clays in catalysis and adsorption.

  12. Salinity dependence of 226Ra adsorption on montmorillonite and kaolinite

    International Nuclear Information System (INIS)

    Shuji Tamamura; Takahiro Takada; Seiya Nagao; Masayoshi Yamamoto; Keisuke Fukushi

    2014-01-01

    The effect of NaCl concentration (10.0-1,000 mM) on 226 Ra adsorption was investigated in the presence of montmorillonite and kaolinite. A positive correlation was observed between the dissolved 226 Ra and NaCl concentrations in the presence of these adsorbents. Distribution coefficients decreased from the order of 10 4 to 10 0 (mL g -1 ) with an increase in NaCl concentration. Although the coefficients were higher for montmorillonite than kaolinite at lower NaCl concentrations, the trend was reversed at higher NaCl concentrations (≥500 mM) owing to the sharper reduction of the coefficient for montmorillonite with the increase in NaCl concentration. The rapid reduction was ascribed to higher negative charge density of montmorillonite, which leads the Ra 2+ adsorption mechanism to approach charge-compensating ion exchange. (author)

  13. Synthesis, thermal properties and applications of polymer-clay nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Meneghetti, Paulo [Chemical Engineering Department, Case Western Reserve University, 10900 Euclid Ave. Cleveland, OH 44106 (United States); Qutubuddin, Syed [Chemical Engineering Department, Case Western Reserve University, 10900 Euclid Ave. Cleveland, OH 44106 (United States)]. E-mail: sxq@case.edu

    2006-03-15

    Polymer-clay nanocomposites constitute a new class of materials in which the polymer matrix is reinforced by uniformly dispersed inorganic particles (usually 10 wt.% or less) having at least one dimension in the nanometer scale. Nanocomposites exhibit improved properties when compared to pure polymer or conventional composites, such as enhanced mechanical and thermal properties, reduced gas permeability, and improved chemical stability. In this work, the synthesis of poly(methyl methacrylate) (PMMA)/clay nanocomposites is described via two methods: in situ and emulsion polymerization. The in situ technique follows a two-step process: ion-exchange of the clay to make it hydrophobic, and polymerization after dispersing the functionalized clay in the monomer. The emulsion technique combines the two steps of the in situ method into one by conducting ion-exchange and polymerization in an aqueous medium in the same reactor. The clay (montmorillonite, MMT) is functionalized with a zwitterionic surfactant, octadecyl-dimethyl betaine (C18DMB). Partially exfoliated nanocomposite, observed by transmission electron microscopy (TEM), was obtained by emulsion polymerization with 10 wt.% clay. Glass transition temperature (T {sub g}) of this nanocomposite was 18 deg. C higher than pure PMMA. With the same clay content, in situ polymerization produced intercalated nanocomposite with T {sub g} 10 deg. C lower than the emulsion nanocomposite. The storage modulus of partially exfoliated nanocomposite was superior to the intercalated structure and to the pure polymer. Using nanocomposite technology, novel PMMA nanocomposite gel electrolytes were synthesized exhibiting improved ionic conductivity and stable lithium interfacial resistance. Nanocomposites can also be used for gas storage and packaging applications as demonstrated by high barrier polymer-clay films.

  14. Synthesis, thermal properties and applications of polymer-clay nanocomposites

    International Nuclear Information System (INIS)

    Meneghetti, Paulo; Qutubuddin, Syed

    2006-01-01

    Polymer-clay nanocomposites constitute a new class of materials in which the polymer matrix is reinforced by uniformly dispersed inorganic particles (usually 10 wt.% or less) having at least one dimension in the nanometer scale. Nanocomposites exhibit improved properties when compared to pure polymer or conventional composites, such as enhanced mechanical and thermal properties, reduced gas permeability, and improved chemical stability. In this work, the synthesis of poly(methyl methacrylate) (PMMA)/clay nanocomposites is described via two methods: in situ and emulsion polymerization. The in situ technique follows a two-step process: ion-exchange of the clay to make it hydrophobic, and polymerization after dispersing the functionalized clay in the monomer. The emulsion technique combines the two steps of the in situ method into one by conducting ion-exchange and polymerization in an aqueous medium in the same reactor. The clay (montmorillonite, MMT) is functionalized with a zwitterionic surfactant, octadecyl-dimethyl betaine (C18DMB). Partially exfoliated nanocomposite, observed by transmission electron microscopy (TEM), was obtained by emulsion polymerization with 10 wt.% clay. Glass transition temperature (T g ) of this nanocomposite was 18 deg. C higher than pure PMMA. With the same clay content, in situ polymerization produced intercalated nanocomposite with T g 10 deg. C lower than the emulsion nanocomposite. The storage modulus of partially exfoliated nanocomposite was superior to the intercalated structure and to the pure polymer. Using nanocomposite technology, novel PMMA nanocomposite gel electrolytes were synthesized exhibiting improved ionic conductivity and stable lithium interfacial resistance. Nanocomposites can also be used for gas storage and packaging applications as demonstrated by high barrier polymer-clay films

  15. Adsorption of chloroacetanilide herbicides on soil and its components. III. Influence of clay acidity, humic acid coating and herbicide structure on acetanilide herbicide adsorption on homoionic clays.

    Science.gov (United States)

    Liu, Wei-ping; Fang, Zhuo; Liu, Hui-jun; Yang, Wei-chun

    2002-04-01

    Adsorption of chloroacetanilide herbicides on homoionic montmorillonite, soil humic acid, and their mixtures was studied by coupling batch equilibration and FT-IR analysis. Adsorption isotherms of acetochlor, alachlor, metolachlor and propachlor on Ca(2+)-, Mg(2+)-, Al(3+)- and Fe(3+)-saturated clays were well described by the Freundlich equation. Regardless of the type of exchange cations, Kf decreased in the order of metolachlor > acetolachlor > alachlor > propachlor on the same clay. FT-IR spectra showed that the carbonyl group of the herbicide molecule was involved in binding, probably via H-bond with water molecules in the clay interlayer. The type and position of substitutions around the carbonyl group may have affected the electronegativity of oxygen, thus influencing the relative adsorption of these herbicides. For the same herbicide, adsorption on clay increased in the order of Mg2+ < Ca2+ < Al3+ < or = Fe3+ which coincided with the increasing acidity of homoionic clays. Acidity of cations may have affected the protonation of water, and thus the strength of H-bond between the clay water and herbicide. Complexation of clay and humic acid resulted in less adsorption than that expected from independent adsorption by the individual constituents. The effect varied with herbicides, but the greatest decrease in adsorption occurred at a 60:40 clay-to-humic acid ratio for all the herbicides. Causes for the decreased adsorption need to be characterized to better understand adsorption mechanisms and predict adsorption from soil compositions.

  16. Synthesis and characterization of carbon nanotubes synthesized over NiO/Na-montmorillonite catalyst and application to a hydrogen peroxide sensor

    International Nuclear Information System (INIS)

    Hsu, H.-L.; Jehng, J.-M.; Liu, Y.-C.

    2009-01-01

    In this study, we demonstrate the synthesis of carbon nanotubes (CNTs) on clay mineral layers, and the preparation of hydrogen peroxide (H 2 O 2 ) sensor based on CNT/Nafion/Na-montmorillonite (Clay) composite film for the detection of H 2 O 2 . The nickel oxide metallic catalyst (NiO) has been prepared by the polyol method and then dispersed onto the clay mineral layers. The CNTs were successfully synthesized over the NiO/Clay catalyst onto clay layers to form a three-dimensional CNT/Clay network by thermal chemical vapor deposition method. From field-emission scanning electron microscope images, the results of X-ray diffraction and Fourier transfer infrared spectra; the layered clay platelets are apparently delaminated and exfoliated after the growth of CNTs onto the surface of clay minerals. The mixed hybrid film of Nafion and CNT/Clay is coated on the glassy carbon electrode to detect hydrogen peroxide (H 2 O 2 ). This composite film performs a detection limit of 1.0 x 10 -4 M for H 2 O 2 and the current is linear for H 2 O 2 concentrations from 0.1 to 12.8 mM. Furthermore, the sensitivity of the GCE modified with the CNT/Clay/Nafion hybrid film to H 2 O 2 was calculated to be 1.71 x 10 5 μA M -1 cm -2 . Consequently, the CNT/Clay/Nafion medium can probably be a useful electrode for the development of sensors due to its high sensitivity and applicability

  17. Synthesis of polymer gel electrolyte with high molecular weight poly(methyl methacrylate)-clay nanocomposite

    International Nuclear Information System (INIS)

    Meneghetti, Paulo; Qutubuddin, Syed; Webber, Andrew

    2004-01-01

    Polymer nanocomposite gel electrolytes consisting of high molecular weight poly(methyl methacrylate) PMMA-clay nanocomposite, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer, and LiClO 4 electrolyte are reported. Montmorillonite clay was ion exchanged with a zwitterionic surfactant (octadecyl dimethyl betaine) and dispersed in methyl methacrylate, which was then polymerized to synthesize PMMA-clay nanocomposites. The nanocomposite was dissolved in a mixture of EC/PC with LiClO 4 , heated and pressed to obtain polymer gel electrolyte. X-ray diffraction (XRD) of the gels indicated intercalated clay structure with d-spacings of 2.85 and 1.40 nm. In the gel containing plasticizer, the clay galleries shrink suggesting intercalation rather than partial exfoliation observed in the PMMA-clay nanocomposite. Ionic conductivity varied slightly and exhibited a maximum value of 8 x 10 -4 S/cm at clay content of 1.5 wt.%. The activation energy was determined by modeling the conductivity with a Vogel-Tamman-Fulcher expression. The clay layers are primarily trapped inside the polymer matrix. Consequently, the polymer does not interact significantly with LiClO 4 electrolyte as shown by FTIR. The presence of the clay increased the glass transition temperature (Tg) of the gel as determined by differential scanning calorimetry. The PMMA nanocomposite gel electrolyte shows a stable lithium interfacial resistance over time, which is a key factor for use in electrochemical applications

  18. Water structure and aqueous uranyl(VI) adsorption equilibria onto external surfaces of beidellite, montmorillonite, and pyrophyllite: results from molecular simulations.

    Science.gov (United States)

    Greathouse, Jeffery A; Cygan, Randall T

    2006-06-15

    Molecular dynamics simulations were performed to provide a systematic study of aqueous uranyl adsorption onto the external surface of 2:1 dioctahedral clays. Our understanding of this key process is critical in predicting the fate of radioactive contaminants in natural groundwaters. These simulations provide atomistic detail to help explain experimental trends in uranyl adsorption onto natural media containing smectite clays. Aqueous uranyl concentrations ranged from 0.027 to 0.162 M. Sodium ions and carbonate ions (0.027-0.243 M) were also present in the aqueous regions to more faithfully model a stream of uranyl-containing groundwater contacting a mineral system comprised of Na-smectite. No adsorption occurred near the pyrophyllite surface, and there was little difference in uranyl adsorption onto the beidellite and montmorillonite, despite the difference in location of clay layer charge between the two. At low uranyl concentration, the pentaaquouranyl complex dominates in solution and readily adsorbs to the clay basal plane. At higher uranyl (and carbonate) concentrations, the mono(carbonato) complex forms in solution, and uranyl adsorption decreases. Sodium adsorption onto beidellite occurred both as inner- and outer-sphere surface complexes, again with little effect on uranyl adsorption. Uranyl surface complexes consisted primarily of the pentaaquo cation (85%) and to a lesser extent the mono(carbonato) species (15%). Speciation diagrams of the aqueous region indicate that the mono(carbonato)uranyl complex is abundant at high ionic strength. Oligomeric uranyl complexes are observed at high ionic strength, particularly near the pyrophyllite and montmorillonite surfaces. Atomic density profiles of water oxygen and hydrogen atoms are nearly identical near the beidellite and montmorillonite surfaces. Water structure therefore appears to be governed by the presence of adsorbed ions and not by the location of layer charge associated with the substrate. The water

  19. Synthesis, characterization and dielectric properties of polynorbornadiene–clay nanocomposites by ROMP using intercalated Ruthenium catalyst

    International Nuclear Information System (INIS)

    Yalçınkaya, Esra Evrim; Balcan, Mehmet; Güler, Çetin

    2013-01-01

    Polynorbornadiene clay nanocomposites were prepared for the first time by the ring opening metathesis polymerization (ROMP) using modified montmorillonite and polynorbornadiene the latter of which is used commonly in electric–electronic industry. The Na–MMT clay was modified by a quaternary ammonium salt containing Ruthenium complex as a suitable catalyst and intercalant as well. The norbornadiene monomers were polymerized within the modified montmorillonite layers by in-situ polymerization method in different clay loading degrees. Intercalation ability of the Ru catalyst and partially exfoliated nanocomposite structure were proved by powder X-ray Diffraction (XRD) Spectroscopy and Transmission Electron Microscopy (TEM) methods. The nanocomposite materials with high thermal degradation temperature and low dielectric constant compared to the pure polynorbornadiene were obtained. The dielectric constants decreased with the increase of the clay content. - Highlights: • Polynorbornadiene–clay nanocomposites were prepared for the first time. • Ruthenium complex was assigned as both suitable catalyst and intercalant. • The norbornadiene was polymerized by in-situ polymerization method. • Exfoliation/intercalation structures were found to be related with loading degree. • PNBD–MMT nanocomposites had a higher thermal degradation temperature and lower dielectric constant

  20. Polyacrylamide sorption opportunity on interlayer and external pore surfaces of contaminant barrier clays.

    Science.gov (United States)

    Inyang, Hilary I; Bae, Sunyoung

    2005-01-01

    Physico-chemical interactions among polymer molecules in aqueous solution and clay mineralogical/textural characteristics influence the sorption of polymer molecules on clay barrier minerals. Amendment of potentially unstable barrier clays with aqueous polymers can improve barrier material resistance to environmental stresses during service. In this research, the ability of molecular coils of polyacrylamide (PAM) to overlap in solution and to enter interlayer space in Na-montmorillonite (specific surface=31.82+/-0.22 m2 g(-1)) and kaolinite (specific surface=18+/-2 m2 g(-1)) were analyzed theoretically and experimentally, using solution viscosity measurements, and X-ray diffractometry. Experimental data on two theoretical indices: relative size ratio (RSR); and molecular availability (Ma) that are formulated to scale polymer molecular sorption on clay interlayer, indicate that the sorption of PAM A (Mw=4000000) and PAM B (Mw=7000000) does not produce any significant change in the d-spacing of both clay minerals. Although the negative Ma values of -3.51 g l(-1) for PAM A and -3.88 g l(-1) for PAM B indicate high levels of entanglement of polymer molecular coils in solution, sorption data confirm that the entangled coils are still able to sorb onto Na-montmorillonite highly and kaolinite to a lesser extent.

  1. Effect of coal mine dust and clay extracts on the biological activity of the quartz surface

    Energy Technology Data Exchange (ETDEWEB)

    Stone, V.; Jones, R.; Rollo, K.; Duffin, R.; Donaldson, K.; Brown, D.M. [Napier University, Edinburgh (United Kingdom). School of Life Science

    2004-04-01

    Modification of the quartz surface by aluminum salts and metallic iron have been shown to reduce the biological activity of quartz. This study aimed to investigate the ability of water soluble extracts of coal mine dust (CMD), low aluminum clays (hectorite and montmorillonite) and high aluminum clays (attapulgite and kaolin) to inhibit the reactivity of the quartz surface. DQ12 induced significant haemolysis of sheep erythrocytes in vitro and inflammation in vivo as indicated by increases in the total cell numbers, neutrophil cell numbers, MIP-2 protein and albumin content of bronchoalveolar lavage (BAL) fluid. Treatment of DQ12 with CMD extract prevented both haemolysis and inflammation. Extracts of the high aluminum clays (kaolin and attapulgite) prevented inhibition of DQ12 induced haemolysis, and the kaolin extract inhibited quartz driven inflammation. DQ12 induced haemolysis by coal mine dust and kaolin extract could be prevented by pre-treatment of the extracts with a cation chellator. Extracts of the low aluminum clays (montmorillonite and hectorite) did not prevent DQ12 induced haemolysis, although the hectorite extract did prevent inflammation. These results suggest that CMD, and clays both low and rich in aluminum, all contain soluble components (possibly cations) capable of masking the reactivity of the quartz surface.

  2. Behavior of clay materials under ionizing radiation

    International Nuclear Information System (INIS)

    Laine, Maxime

    2017-01-01

    The aim of this PhD thesis is to study and understand, by proposing reaction mechanisms, the behavior under irradiation of various clay materials. The systems of interest were first synthetic talc, which is the prototype of a non-swelling material. Under irradiation by accelerated electrons, the production of dihydrogen in this system, due solely to surface hydroxyl groups, is of the same order of magnitude as the one obtained in liquid water. This yield is divided by 30 in the case of natural talc from Luzenac, thus highlighting the importance of the impurities as scavengers of the precursors of dihydrogen. Synthetic smectites, which are swelling materials, were then studied. The results evidence the radiolysis of water confined in the interlayer space, leading to H 2 yields which may be two to three times higher than those measured in water. Moreover, they are similar for montmorillonite and saponite, evidencing that the charge location plays only a minor role. Finally, the study of double layered hydroxides or anionic clays shows that, in this case, the nature of the anion in the inter lamellar space controls the reactivity. Parallel to these measurements, electron paramagnetic spectroscopy experiments have enabled proposing reaction mechanisms. Finally, all these results are of interest in the context of the disposal of radioactive waste. (author) [fr

  3. Quantum-chemical modeling of smectite clays

    Science.gov (United States)

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

    1982-01-01

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

  4. Preparation of polymer-organo clay nano composites through the spray drying process

    International Nuclear Information System (INIS)

    Bernardo, Paulo R.A.; Pessan, Luiz A.; Carvalho, Antonio J.F. de; Vidotti, Suel E.

    2011-01-01

    The objective of the work was the study and preparation of polymer nano composites with montmorillonite organo clays (MMT) through the spray drying process. A new technique was proposed and tested to obtaining polymer nano composites, based on the use of the spray drying process to produce a nano composite with high clay content. The process consisted of the following stages: clay intercalation in water solution, with after addition of polyvinyl alcohol (PVOH) and a hydro soluble polyester ionomer (GEROLPS20) as exfoliation agents; spray drying the mixture obtained; incorporation powder in EVOH, PET e PP matrix. The effects of exfoliation agent on morphological and thermal properties of the nano composites were studied by XRD, transmission electron microscopy (TEM) and TGA. The results demonstrate that the process of spray drying is an innovative way to obtain a nano composite with high clay content. (author)

  5. Improving the procedure for obtaining organophilic clays; Aperfeicoamento da tecnica de obtencao de argilas organofilicas

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, S.S.; Carvalho, L.H. de; Silva, S.M.L., E-mail: suedina@dema.ufcg.edu.b [Universidade Federal de Campina Grande (UAEMa/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Raposo, C.M.O. [Universidade Federal de Campina Grande (UAMG/UFCG), PB (Brazil). Unidade Academica de Mineracao e Geologia

    2009-07-01

    This study was realized in order to improve the way to obtain organoclays using clay from clay a local industry. Thus, factors not yet well understood in regard to organoclays were optimized and elucidated in this work. In the preparation of organoclays, a sodium bentonite, from the Bentonit Uniao Nordeste-Campina Grande/PB, was purified and organically modified with quaternary ammonium salt, cetyl trimethyl ammonium bromide (Cetrimide), using different conditions of preparation (time of mixing and content of organic surfactant). For purposes of comparison it was used also a commercial sodium montmorillonite (Cloisite Na{sup +}), supplied by Southern Clay Products. Infrared spectroscopy (FTIR) and X ray diffraction (XRD) data indicated that organoclays more thermally stable and with better cost/benefit ratio can be prepared using the lowest mixing time (30 min) and the lowest amount of surfactant (equivalent to 100% of CEC of clay). (author)

  6. A desk study of surface diffusion and mass transport in clay

    International Nuclear Information System (INIS)

    Cook, A.J.

    1988-09-01

    The concept of a geological barrier to radionuclide migration from theoretical radioactive waste repositories has drawn attention to the physico-chemical properties of clays, which are traditionally regarded as retarding media. This report addresses the different mechanisms of transport of radionuclides through clay and in particular focuses on the surface diffusion movement of sorbed cations. The relative contributory importance of the different transport mechanisms is governed by the pore size distributions and interconnections within the clay fabric. Surface diffusion data in the literature have been from experiments using compacted montmorillonite and biotite gneiss. A possible programme of laboratory work is outlined, based on diffusion experiments, which describes the way of measuring the effect of surface diffusion more accurately in clays, mudstones and shales. (author)

  7. A method for producing electrolyte and heat resistant drilling muds from bentonite clays

    Energy Technology Data Exchange (ETDEWEB)

    Koyev, K; Bedelcheva, A; Uzunova, I

    1979-01-01

    A method is developed for producing clay suspensions, which are resistant to electrolytes, high temperature and pressure, on the basis of bentonite clays with a high content of montmorillonite. The method is based on the subsequent introduction into the suspension of magnesium chloride (calcium chloride) and sodium chloride with intense mixing and maintenance of the high viscosity of the clay mass. The electrolytes are added in a specific order and volume: the magnesium chloride or calcium chloride at 1-3% and the sodium chloride at approximately 30%. The clay suspensions are characterized by high SNS and filtration (40 cm/sup 3/ in 30 min). The operational indicators may be regulated so that they remain in accordance with the required standards.

  8. Use of clays as buffers in radioactive repositories

    International Nuclear Information System (INIS)

    Pusch, R.

    1983-05-01

    For use as canister overpack, highly compacted bentonite is superior to illite and any reasonably montmorillonite-rich bentonite will do which is not too rich in sulphur. The organic content should be low and heat treatment may be required to bring this content down to an acceptable level. Heating to slightly more than 400degreeC does not affect the physical properties of neither montmorillonite, nor illite to a significant extent. Bentonite is also very suitable for use as sealing plugs in the form of highly compacted blocks. For use as backfill in tunnels and shafts, illitic clay is a candidate material which can be compacted on site to the rather high density that is required. Where a swelling capacity is needed, such as in the top part of tunnels, bentonite-based backfills are suitable and if Na saturated clay is used the bentoite fraction can be kept low. Thus, a 10 percent content of Na bentonite by weight should generally be sufficient for a well compacted mixture with respect to the required hydraulic conductivity, while a 20-30 percent content may be needed to arrive at a sufficient swelling power. The choice of a suitable clay material requires that the substance be properly characterized and tested. It is concluded that rather rigorous analyses are necessary as concerns overpacks, including mineralogical and granulometrical tests and the determination of the swelling characteristics as well as of certain chemical features. For backfills and for the current checking of all sorts of clay for use as buffer materials, the natural water content, the liquid limit and the swelling ability have to be determined, since they are the fingerprints of this type of soil. (author)

  9. Development of clay characterization methods for use in repository design with application to a natural Ca bentonite clay containing a redox front

    International Nuclear Information System (INIS)

    Karnland, O.; Pusch, R.

    1990-12-01

    Natural smectite clays in the form of 'true' bentonites formed from volcanic ash, or resulting from in-situ weathering of rock, are suitable for a number of sealing options in repositories, both as tightening component of sand/clay backfills and as highly efficient buffer for embedment of canisters, as well as for fracture sealing. The price and quality, in terms of smectite content and type of smectite, vary considerably and an optimum choice of clay for use in repositories has to be based on quantitative quality data. This requires characterization of the clay material for which a test scheme has been worked out. It comprises determination of the granulometrical, chemical, and mineralogical compositions, as well as of certain physical properties. Recent research shows the importance of the type of smectite for the longevity of buffers in repository environment, beidellite being less favourable and saponite superior to montmorillonite, which is the most common smectite species. The test scheme hence includes means of distinguishing between various smectite minerals. The influence of accessory minerals on the chemical integrity of both the smectite and the canister material requires identification also of such minerals, for which the scheme is useful as well. The report summarizes the various test procedures and gives data from application of the scheme to samples from a natural Ca bentonite containing a redox front. This study suggests that a significant part of the iron in the clay fraction is in the form of Fe 2+ in octahedral positions of the montmorillonite of unoxidized natural clay and that it is converted to Fe 3+ on oxidation. Part of the iron is probably in the form of the Fe 2+ Fe 3+ hydroxy compounds that give the unoxidized clay its bluish colour, while they can be assumed to be transformed to yellowish FeOOH forms on oxidation. (author)

  10. Study of sodium clay modification through polyaniline polymerization

    International Nuclear Information System (INIS)

    Saade, Wesley; Pinto, Camila P.; Becker, Daniela; Dalmolin, Carla

    2015-01-01

    The synthesis of hybrids nanocomposites, such as polyaniline/montmorillonite (Pani/MMT), combines the processability and electrical conductivity of this polymer with the mechanical properties of a ceramic material bringing a multitude of new possibilities for use in high-tech, consumer and industry. With this in mind, we sought to characterize and modify sodium clay through polymerization of polyaniline. The characterization was carried out by X-ray diffraction, infrared spectroscopy by Fourier transformed (FTIR) and spectroscopy by impedance. Through the XRD analysis, it could be inferred that there was a interplanar displacement from 12,4Å (pure sodium montmorillonite) to 15,6Å due to the cation exchange of Na + ions by the anilinium ions, allowing the polymerization interspersed with Pani MMT platelets. By FTIR analysis, presences of the characteristic functional groups of both compounds are detected in the synthesized nanocomposite. Through conductivity and impedance tests it is concluded that the addition of polyaniline decreases the resistive behavior of clay and the electrical conduction becomes possible. (author)

  11. Effects of simulated clay gouges on the sliding behavior of Tennessee sandston

    Science.gov (United States)

    Shimamoto, Toshihiko; Logan, John M.

    1981-06-01

    The effects of simulated fault gouge on the sliding behavior of Tennessee sandstone are studied experimentally with special reference to the stabilizing effect of clay minerals mixed into the gouge. About 30 specimens with gouge composed of pure clays, of homogeneously mixed clay and anhydrite, or of layered clay and anhydrite, along a 35° precut are deformed dry in a triaxial apparatus at a confining pressure of 100 MPa, with a shortening rate of about 5 · 10 -4/sec, and at room temperature. Pure clay gouges exhibit only stable sliding, and the ultimate frictional strength is very low for bentonite (mont-morillonite), intermediate for chlorite and illite, and considerably higher for kaolinite. Anhydrite gouge shows violent stick-slip at 100 MPa confining pressure. When this mineral is mixed homogeneously with clays, the frictional coefficient of the mixed gouge, determined at its ultimate frictional strength, decreases monotonically with an increase in the clay content. The sliding mode changes from stick-slip to stable sliding when the frictional coefficient of the mixed clay-anhydrite gouge is lowered down below 90-95% of the coefficient of anhydrite gouge. The stabilizing effect of clay in mixed gouge is closely related to the ultimate frictional strength of pure clays; that is, the effect is conspicuous only for a mineral with low frictional strength. Only 15-20% of bentonite suppresses the violent stick-slip of anhydrite gouge. In contrast, violent stick-slip occurs even if the gouge contains as much as 75% of kaolinite. The behavior of illite and chlorite is intermediate between that of kaolinite and bentonite. Bentonite—anhydrite two-layer gouge exhibits stable sliding even when the bentonite content is only 5%. Thus, the presence of a thin, clay-rich layer in a fault zone stabilizes the behavior much more effectively than do the clay minerals mixed homogeneously with the gouge. This result brings out the mechanical significance of internal structures

  12. Characterization of polyurethane/organophilic montmorillonite nanocomposites by low field NMR

    International Nuclear Information System (INIS)

    Silva, Marcos Anacleto da; Tavares, Maria I.B.; Nascimento, Suelen A.M.; Rodrigues, Elton J. da R

    2012-01-01

    Polyurethanes are important and versatile materials, mainly due to some of their properties, such as high resistance to abrasion and tearing, excellent absorption of mechanical shocks and good flexibility and elasticity. However, they have some drawbacks as well, such as low thermal stability and barrier properties. To overcome these disadvantages, various studies have been conducted involving organophilic polyurethane/montmorillonite nanocomposites. The investigation of the structure of polyurethane/clay nanocomposites has mainly been done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). In this work, PU/clay nanocomposite films obtained by solution intercalation were studied. The nanocomposites were characterized by XRD and low-field nuclear magnetic resonance (LF-NMR). The LF-NMR measurements, with determination of the spin-lattice relaxation time of the hydrogen nucleus, supplied important information about the molecular dynamics of these nanocomposites. The X-ray diffraction measurements validated the results found by NMR. The thermal stability of the material was also determined by thermogravimetric analysis (TGA) under an inert atmosphere. A slight improvement in this stability was observed in the nanocomposite in comparison with polyurethane (author)

  13. Adsorption behavior of strontium on kaolinite and montmorillonite and their mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Atun, G. [Istanbul Univ. (Turkey). Engineering Faculty, Chemistry Dept.; Bascetin, E. [Cekmece Nuclear Research and Training Center, Istanbul (Turkey)

    2004-07-01

    {sup 90}Sr, with a long half-life of 28.5 years, is the most dangerous strontium isotope. The adsorption behavior of radionuclides in the environment are closely related to the safe disposal of radioactive wastes. Since various types of minerals may exist in and around the repositories used for ultimate disposal of nuclear waste, the adsorption behavior of certain radionuclides onto and from these minerals and similar adsorbents should be studied in order to estimate the rates of transport of the nuclides in the event of water penetration into and through the repository. Information on the adsorption properties of the purified individual clay minerals may not be sufficient to predict the adsorption properties of a corresponding mixture, because these clay minerals may interact with each other and lead to modification of the adsorption properties of the mixture as compared to the pure minerals. The adsorption behavior of strontium on kaolinite and montmorillonite minerals and their mixtures was studied by means of a batch method and a tracer technique. (orig.)

  14. Adsorption of barium on kaolinite, illite and montmorillonite at various ionic strengths

    Energy Technology Data Exchange (ETDEWEB)

    Atun, G.; Bascetin, E. [Istanbul Univ., Dept. of Chemistry, Istanbul (Turkey)

    2003-07-01

    The sorption behaviour of Ba{sup 2+} in three different clay minerals from various regions of Turkey has been investigated by means of a tracer technique using {sup 133}Ba in batch experiments. Sorption of Ba{sup 2+} on montmorillonite, kaolinite and illite has been studied in mixed solutions of BaCl{sub 2} and NaCl at ionic strengths ranging from 1 x 10{sup -3}M to 1 x 10{sup -1}M. The L-shape exchange isotherms for Ba{sup 2+}-Na{sup +} systems are well defined by a Langmuir type equation. The exchange capacity of Ba{sup 2+} ions for all three clay minerals increased with decreasing ionic strength. The adsorption data were fitted to a Freundlich isotherm and empirical Freundlich parameters enabled to the generation of a site distribution function. The selectivity coefficients were nearly constant at low Ba loading and decreased as loading increased. This behavior was an indication of an ion exchange process between Ba{sup 2+} and Na{sup +} ions.

  15. Insightful understanding of the role of clay topology on the stability of biomimetic hybrid chitosan-clay thin films and CO2-dried porous aerogel microspheres.

    Science.gov (United States)

    Frindy, Sana; Primo, Ana; Qaiss, Abou El Kacem; Bouhfid, Rachid; Lahcini, Mohamed; Garcia, Hermenegildo; Bousmina, Mosto; El Kadib, Abdelkrim

    2016-08-01

    Three natural clay-based microstructures, namely layered montmorillonite (MMT), nanotubular halloysite (HNT) and micro-fibrillar sepiolite (SP) were used for the synthesis of hybrid chitosan-clay thin films and porous aerogel microspheres. At a first glance, a decrease in the viscosity of the three gel-forming solutions was noticed as a result of breaking the mutual polymeric chains interaction by the clay microstructure. Upon casting, chitosan-clay films displayed enhanced hydrophilicity in the order CSclay microstructure, an improvement in the mechanical properties of the chitosan-clay films has been substantiated with CS-SP reaching the highest value at 5% clay loading. While clay addition provides a way to resist the shrinkage occurring for native chitosan, the enhanced hydrophilicity associated to the water content affects the efficacy of the CO2 super-critical drying as the most hydrophilic CS-SP microspheres face the highest shrinkage, resulting in a lowest specific surface area compared to CS-HNT and CS-MMT. Chitosan-clay exhibits enhanced thermal properties with the degradation delayed in the order CSclay compared to native chitosan, evidencing the beneficial protective effect of the clay particulates for the biopolymer. However, under hydrothermal treatment, the presence of clay was found to be detrimental to the material stability as a significant shrinkage occurs in hybrid CS-clay microspheres, which is attributed again to their increased hydrophilicity compared to the native polymeric microspheres. In this framework, a peculiar behavior was observed for CS-MMT, with the microspheres standing both against contraction during CO2 gel drying and under hydrothermal conditions. The knowledge gained from this rational design will constitute a guideline toward the preparation of ultra-stable, practically-optimized food-packaging films and commercially scalable porous bio-based adsorbents. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Enhanced desorption of Cs from clays by a polymeric cation-exchange agent

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chan Woo, E-mail: park85@gmail.com [Decontamination & Decommissioning Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon (Korea, Republic of); Kim, Bo Hyun [Decontamination & Decommissioning Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon (Korea, Republic of); Department of Chemical Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Yang, Hee-Man; Seo, Bum-Kyoung [Decontamination & Decommissioning Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Kune-Woo, E-mail: nkwlee@kaeri.re.kr [Decontamination & Decommissioning Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon (Korea, Republic of)

    2017-04-05

    Highlights: • A cationic polyelectrolyte has excellent ability to desorb Cs bound strongly to clay. • The polycation desorbed significantly more Cs from the clay than did single cations. • Additional NH{sub 4}{sup +} treatment following the polycation treatment enhanced desorption of Cs. • The reaction yielded efficient desorption (95%) of an extremely low concentration of Cs-137 in the clay. - Abstract: We report on a new approach to increase the removal of cesium from contaminated clays based on the intercalation of a cationic polyelectrolyte into the clay interlayers. A highly charged cationic polyelectrolyte, polyethyleneimine (PEI), was shown to intercalate into the negatively charged interlayers and readily replaced Cs ions adsorbed on the interlayers of montmorillonite. The polycation desorbed significantly more Cs strongly bound to the clay than did single cations. Moreover, additional NH{sub 4}{sup +} treatment following the PEI treatment enhanced desorption of Cs ions that were less accessible by the bulky polyelectrolyte. This synergistic effect of PEI with NH{sub 4}{sup +} yielded efficient desorption (95%) of an extremely low concentration of radioactive {sup 137}Cs in the clay, which is very difficult to remove by simple cation-exchange methods due to the increased stability of the binding of Cs to the clay at low Cs concentrations.

  17. Study of Adsorption of Phenanthrene on Different Types of Clay Minerals

    International Nuclear Information System (INIS)

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

    2003-01-01

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

  18. Purification and characterization of smectite clay taken from Gafsa, Tunisia: Progressive elimination of carbonates

    International Nuclear Information System (INIS)

    Mhamdi, M; Gasmi, N; Elaloui, E; Kbir-Ariguib, N; Trabelsi-Ayadi, M

    2010-01-01

    This work shows the results of various analysis on a representative clay sample from southern west of Tunisia, particularly from Oued Tfal near the town of Gafsa. The raw smectite contains some carbonate, quartz, chlorite, and anorthite. During the attack of the carbonate clay with a solution of hydrochloric acid, a change of the chemical composition and physical properties was observed. This change is dependent on several factors: the initial concentration of the acid, the nature of the clay, the ratio acid / clay...). Although treatment to 0.5 M represents a total removal of carbonates, there are probably altered layers of the clay fraction. The result shows that for a treatment with acid solutions of concentrations below 0.5 M there is gradual removal of carbonate without protonation of the clay layers. The characterization of the clay fraction shows that the sodium clay purified (OTNa) consists of a sodium montmorillonite smectite. The cation exchange capacity and the specific surface of OTNa measured using the method of methylene blue are equal to 82 meq/100g and 667 m 2 / g respectively.

  19. Characterization of karak clay from pakistan for pharmaceutical and cosmetic applications

    International Nuclear Information System (INIS)

    Shah, L.A.; Silva-Valenzuela, M.G.; Valenzuela-Diaz, F.R.; Sayeg, I.J.; Carvalho, F.M.S.

    2012-01-01

    Full text: Clay, the most important, plentiful, and low cost naturally occurring mineral, is widely used in variety of industrial application including Pharmaceutical and cosmetic. Clay is the fine grained aluminosilicate mineral which shows the property of plasticity at appropriate water content, and becomes hard upon drying. In Pakistan there are different types of clay but till now neither of them properly identified nor characterize for specific industrial application. The objective of this work is to characterize Karak clay for pharmaceutical and cosmetic applications collected from deposit located at Shagai region, District Karak, Pakistan. The clay was characterized through Xray diffractometry (XRD), X-ray Fluorescence (XRF), trace elemental Analysis, Microbiological analysis, Cation exchange capacity (CEC), pH and swelling assays according to European, United States of America and Brazilian Pharmacopeias. Bulk Chemical analysis shows that the Aluminum oxide and silica oxide are present in large quantity which was confirmed by XRD that this sample has montmorillonite as a major while illite and kaolinite as minor clay minerals. Quartz of small quantity was also found as a non-clay mineral. After analyzing the results for sample it was concluded that the clay is a strong candidate for cosmetic purposes. (author)

  20. Study of PP/montmorillonite composite degradation

    International Nuclear Information System (INIS)

    Baer, Marcia; Granado, Carlos J.F.

    2009-01-01

    The objective of this work was to produce composites of PP/sodium bentonite and PP/ organophilic bentonite through melt intercalation and analyze the degradation produced by ultraviolet irradiation. The XRD results showed that the samples of nature bentonite had better interaction with de polymer and produced intercalated nanocomposite. The effect of UV irradiation on degradation was observed after 24 hours of exposition. The samples showed the same photoproducts and at the same proportion until 240 hours of UV exposition; with 480 hours the organophilize bentonite composite showed higher degradation than other ones. The superficial cracks increased with degradation time. The degradation occurs due chromophores impurities presented in the samples, thus samples with sodium clay show higher degradation, and organophilic clay contains ammonium salt that contribute to increase the degradation. (author)

  1. Modification of reduced-charge montmorillonites by a series of Gemini surfactants: Characterization and application in methyl orange removal

    International Nuclear Information System (INIS)

    Luo, Zhongxin; Gao, Manglai; Ye, Yage; Yang, Senfeng

    2015-01-01

    Highlights: • RCMs were modified by three Gemini surfactants with different spacer length. • The adsorption kinetics and thermodynamics of MO on organoclays were investigated. • Both the spacer length and clay layer charge have significant effects on the removal of MO. • The removal efficiency of MO increased with increasing clay layer charge. • Gemini surfactants modified RCMs were low-cost and high efficient adsorbents for the uptake of MO. - Abstract: The influences that the spacer chain length of Gemini surfactants and clay layer charge have on the structures and sorption characteristics of organoclays have been investigated. Organoclays were obtained by modifying a series of reduced charge montmorillonites (RCMs) using three Gemini surfactants with different spacer length. And their structures and sorption characteristics for methyl orange (MO) were examined. It was suggested that the amount, spacer length of Gemini surfactant and clay layer charge had significant effects on the microstructure of the organoclays. The adsorption experiments results claimed that the uptake of MO onto organoclays was in the order: 16-4-16-Mt > 16-8-16-Mt > 16-6-16-Mt, while it increased with increasing clay layer charge. The adsorption isotherms of MO onto the organoclays could be best described by Langmuir equation, and the adsorption kinetic was in good agreement with the pseudo-second-order model. Thermodynamic parameters demonstrated that the sorption process was spontaneous and endothermic in nature. This work will provide a deep insight into the interaction of Gemini-modified clays and MO, which pave the way for their practical applications in anionic dye adsorption

  2. Modification of reduced-charge montmorillonites by a series of Gemini surfactants: Characterization and application in methyl orange removal

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Zhongxin; Gao, Manglai, E-mail: mlgao@cup.edu.cn; Ye, Yage; Yang, Senfeng

    2015-01-01

    Highlights: • RCMs were modified by three Gemini surfactants with different spacer length. • The adsorption kinetics and thermodynamics of MO on organoclays were investigated. • Both the spacer length and clay layer charge have significant effects on the removal of MO. • The removal efficiency of MO increased with increasing clay layer charge. • Gemini surfactants modified RCMs were low-cost and high efficient adsorbents for the uptake of MO. - Abstract: The influences that the spacer chain length of Gemini surfactants and clay layer charge have on the structures and sorption characteristics of organoclays have been investigated. Organoclays were obtained by modifying a series of reduced charge montmorillonites (RCMs) using three Gemini surfactants with different spacer length. And their structures and sorption characteristics for methyl orange (MO) were examined. It was suggested that the amount, spacer length of Gemini surfactant and clay layer charge had significant effects on the microstructure of the organoclays. The adsorption experiments results claimed that the uptake of MO onto organoclays was in the order: 16-4-16-Mt > 16-8-16-Mt > 16-6-16-Mt, while it increased with increasing clay layer charge. The adsorption isotherms of MO onto the organoclays could be best described by Langmuir equation, and the adsorption kinetic was in good agreement with the pseudo-second-order model. Thermodynamic parameters demonstrated that the sorption process was spontaneous and endothermic in nature. This work will provide a deep insight into the interaction of Gemini-modified clays and MO, which pave the way for their practical applications in anionic dye adsorption.

  3. 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

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

    International Nuclear Information System (INIS)

    Papageorgiou, George Z.; Karandrea, Eva; Giliopoulos, Dimitrios; Papageorgiou, Dimitrios G.; Ladavos, Athanasios; Katerinopoulou, Aikaterini; Achilias, Dimitris S.; Triantafyllidis, Konstantinos S.; Bikiaris, Dimitrios N.

    2014-01-01

    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 g in the Lauritzen–Hoffman analysis. This is due to its better dispersion and exfoliation

  5. Common clay and shale

    Science.gov (United States)

    Virta, R.L.

    2000-01-01

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

  6. Methylene blue adsorption in clay mineral dealt with organic cation

    International Nuclear Information System (INIS)

    Silva, T.L.; Lemos, V.P.

    2011-01-01

    The interaction among organic cations, as the methylene blue (AM) and benzyltrimethylammonium (BTMA), and clay minerals of the group of the smectite they result in the formation of applied materials in the adsorption of organic pollutant presents in waters, soils and you cultivate. In this work they were prepared the adsorbents (organic-clays) smectite - AM and smectite-BTMA. The precursory sample of smectite was collected in Rio Branco-Acre. We were also used an smectite sample collected in Sena Madureira (SM)-Acre already characterized in previous work and a sample of standard smectite Swy-2-Na-Montmorillonite (SWy-2) of Wymong - USA. The organic agents selected for this study they were: Blue of Methylene, denominated AM and Benzyltrimethylammonium, denominated BTMA. They were appraised the capacities adsorptive of the treated samples with BTMA being used AM as adsorbate. The results of these evaluations detected that ran total adsorption of AM (concentrations varying from 1 to 10 ppm) for the treated samples with BTMA. The organic cation, BTMA, interacting with the surfaces of the natural clay was more efficient in the adsorption of AM than the clay without the previous treatment with this salt. (author)

  7. Hydrothermal behaviour of sedimentary saponitic clays from Madrid Basin

    International Nuclear Information System (INIS)

    Cuevas Rodriguez, J.

    1993-01-01

    The hydrothermal behavior of sedimentary saponitic clays from Madrid Basin has been investigated to assess their potential use as a buffer material in high level radioactive waste repositories. This paper deals with a review of several aspects that has been studied: the adsorption and irreversible fixation of K'+, the alteration in absence of potassium and the effects of heat and steam on textural properties of the smectitic clay. Experiments have covered temperatures up to 175 degree centigree with an excess of liquid water except on the last subject. Chemical and XRD analyses of final clay products and solutions indicates minor alteration of the saponite in the hydrothermal experiments either in the presence or absence of potassium. No illitization or chloritization processes seems to affect the smectite. Sepiolite was found to be largely dissolved at 175 degree centigree, a process that inhibited recrystallization or formation of illite observed when illite was present in significant amounts in starting materials. Accessory minerals (illite and sepiolite) accompanying as traces the saponitic material underwent and intense degradation at 175 degree centigree in absence of potassium. On the other hand, clay steamed at 200 degree centigree showed significant textural changes forming highly stable silt size aggregates which hindered the swelling abilities of the saponitic material, a fact that was previously observed in montmorillonites. (Author) 25 refs

  8. Influence of processing conditions in PEA/organophilic clay nanocomposites

    International Nuclear Information System (INIS)

    Araujo, E.M.; Kojuch, L.R.; Barbosa, R.; Nobrega, K.C.; Melo, T.J.A. de

    2008-01-01

    Polymer/clay nanocomposites have attracted great interest from the industry as well as from the researches due to the need to obtain materials with desired properties. Nanocomposites with silicates layer represent an alternative for the conventional composites because they use a small amount of nanofiller. In this work, polyethylene/polyethylene grafted anhydride maleic (PE-g-MA)/montmorillonite clay (MMT) nanocomposites were prepared by melt intercalation in a Torque Rheometer. It was used an untreated clay (MMT) and a treated clay with the quaternary ammonium salt (OMMT). The influence of the processing conditions was evaluated, that is: 60 and 120rpm, 7 and 14 min, 190 and 220°C. The obtained systems were characterized by X-ray diffraction (XRD) and rheological behavior. The results from XRD and rheological behavior indicated that the system composed of polyethylene/PE-g-MA/OMMT presented intercalated nanocomposite structure, with larger basal distance and high viscosity, in the conditions of 120rpm and 7min, independent of temperature. (author)

  9. Polymerization of alanine in the presence of a non-swelling montmorillonite

    Science.gov (United States)

    Paecht-Horowitz, M.; Lahav, N.

    1977-01-01

    Alanine, starting from alanine-adenylate, has been polymerized in the presence of non-swelling Al-montmorillonite. The yield of polymerization is much lower than that obtained in the presence of swelling Na-montmorillonite. The possibility that the changing interlayer spacing in Na-montmorillonite might be responsible for its catalytic properties, is discussed.

  10. The adsorption of Cs+ from wastewater using lithium-modified montmorillonite caged in calcium alginate beads.

    Science.gov (United States)

    Xia, Meng; Zheng, Xianming; Du, Mingyang; Wang, Yingying; Ding, Aizhong; Dou, Junfeng

    2018-07-01

    The increasing nuclear energy consumption has posed serious environmental concerns (e.g. nuclear leakage), and the removal of radionuclides such as cesium becomes an urgent issue to be solved currently. In this research, a novel non-toxic adsorbent lithium-modified montmorillonite clay encapsulated in calcium alginate microbeads (MCA/Li) was fabricated by using ion-exchange method and then used successfully in the remediation of cesium-contaminated wastewater. Analyses of scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the physicochemical properties of adsorbent MCA/Li, such as internal crystal structure, constituent elements, and functional groups. The effects of concentration ratios (sodium alginate/montmorillonite), solution pH, contacting time and initial Cs + concentration on the adsorption behavior were carefully investigated via batch adsorption experiments. The adsorbent MCA/Li exhibited higher selectivity and removal efficiency towards Cs + with the maximum adsorption capacity of 100.25 mg/g. In the kinetics study, the pseudo-first-order fitted the cesium adsorption data of MCA/Li better than the pseudo-second-order. The adsorption mechanism studies revealed the process followed the Langmuir isotherm model, which suggested that Cs + adsorption onto MCA/Li is a monolayer homogeneous adsorption process. The research findings indicated this novel adsorbent MCA/Li demonstrated great potential in radioactive wastewater treatment due to its convenience in synthesis, high adsorption capacity, and low cost. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Polyvinyl alcohol/chitosan/montmorillonite nanocomposites preparation by freeze/thaw cycles and characterization

    Directory of Open Access Journals (Sweden)

    Părpăriţă Elena

    2014-12-01

    Full Text Available Polyvinyl alcohol (PVA and chitosan (CS based hydrogels are often chosen to obtain hydrogels as being considered non-toxic for human body. The present study aims the preparation and physical chemical characterisation of hydrogels based PVA and CS by using an environmental friendly method i.e. freeze/thaw. In this method the only parameters affecting the hydrogels’ properties is the PVA concentration in solution, time and number of cycles of freezing / thawing. Repeated freezing and thawing cycles resulted in production of a highly elastic polyvinyl alcohol hydrogel with higher degree of crystallization. Adding chitosan in polyvinyl alcohol hydrogel is giving to the newly formed material, biocompatibility and antibacterial properties due to the free amino groups of chitosan. Higher mechanical and thermal characteristics of PVA/CS based hydrogels were obtained by addition of a small amount of inorganic nanoparticles (montmorillonite clay, C30B into the matrix (i.e. 1%. Scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FT-IR, near-infrared chemical imaging spectroscopy (NI-CI, X-ray diffraction (XRD, thermogravimetric analysis (TG, swelling and rheological measurements were used to characterize the polyvinyl alcohol/chitosan/montmorillonite properties. The swelling degree increased with decreasing chitosan content in hydrogels and the variation is opposite in nanocomposites, decreasing after introducing the nanoclay. The swelling behaviour was influenced by the presence of the nanoparticles. The plasticizer effect of the nanoparticles was reflected by obtaining a more compact hydrogel network with higher mechanical and thermal properties. The proposed materials can be a promising alternative in biomedical applications

  12. Montmorillonite surface properties and sorption characteristics for heavy metal removal from aqueous solutions

    International Nuclear Information System (INIS)

    Ijagbemi, Christianah Olakitan; Baek, Mi-Hwa; Kim, Dong-Su

    2009-01-01

    Surface properties of montmorillonite (MMT) and its adsorption characteristics for heavy metals have been investigated with nickel and copper as sorbate from aqueous solutions. Employing the potentiometric and mass titration techniques in batch experimental methods, the point of zero charge (PZC) and point of zero net proton charge (PZNPC) of MMT edges at different ionic strengths present pH PZC and pH PZNPC to be 3.4 ± 0.2. A crossing point was observed for the proton adsorption vs. pH curves at different ionic strengths of KCl electrolyte and in investigating MMT remediation potentialities as sorbent for heavy metals polluted waters, the effects of heavy metal concentration, pH, MMT dosage, reaction time and temperature for Cu 2+ and Ni 2+ uptake were studied. The sorption of metal ions by MMT was pH dependent and the adsorption kinetics revealed sorption rate could be well fitted by the pseudo-second-order rate model. The data according to mass transfer and intraparticle diffusion models confirmed diffusion of solutes inside the clay particles as the rate-controlling step and more important for the adsorption rate than the external mass transfer. Adsorption isotherms showed that the uptake of Cu 2+ and Ni 2+ could be described by the Langmuir model and from calculations on thermodynamic parameters, the positive ΔG o values at different temperatures suggest that the sorption of both metal ions were non-spontaneous. Change in enthalpy (ΔH o ) for Ni 2+ and Cu 2+ were 28.9 and 13.27 kJ/mol K respectively, hence an endothermic diffusion process, as ion uptake increased with increase in temperature. Values of ΔS o indicate low randomness at the solid/solution interface during the uptake of both Cu 2+ and Ni 2+ by MMT. Montmorillonite has a considerable potential for the removal of heavy metal cationic species from aqueous solution and wastewater.

  13. Common African cooking processes do not affect the aflatoxin binding efficacy of refined calcium montmorillonite clay.

    Science.gov (United States)

    Elmore, Sarah E; Mitchell, Nicole; Mays, Travis; Brown, Kristal; Marroquin-Cardona, Alicia; Romoser, Amelia; Phillips, Timothy D

    2014-03-01

    Aflatoxins are common contaminants of staple crops, such as corn and groundnuts, and a significant cause of concern for food safety and public health in developing countries. Aflatoxin B 1 (AFB 1 ) has been implicated in the etiology of acute and chronic disease in humans and animals, including growth stunting, liver cancer and death. Cost effective and culturally acceptable intervention strategies for the reduction of dietary AFB 1 exposure are of critical need in populations at high risk for aflatoxicosis. Fermented gruels consisting of cornmeal are a common source for such exposure and are consumed by both children and adults in many countries with a history of frequent, high-level aflatoxin exposure. One proposed method to reduce aflatoxins in the diet is to include a selective enterosorbent, Uniform Particle Size NovaSil (UPSN), as a food additive in contaminated foods. For UPSN to be effective in this capacity, it must be stable in complex, acidic mixtures that are often exposed to heat during the process of fermented gruel preparation. Therefore, the objective of the present study was to test the ability of UPSN to sorb aflatoxin while common cooking conditions were applied. The influence of fermentation, heat treatment, acidity, and processing time were investigated with and without UPSN. Analyses were performed using the field-practical Vicam assay with HPLC verification of trends. Our findings demonstrated that UPSN significantly reduced aflatoxin levels (47-100%) in cornmeal, regardless of processing conditions. Upon comparison of each element tested, time appeared to be the primary factor influencing UPSN efficacy. The greatest decreases in AFB 1 were reported in samples allowed to incubate (with or without fermentation) for 72 hrs. This data suggests that addition of UPSN to staple corn ingredients likely to contain aflatoxins would be a sustainable approach to reduce exposure.

  14. Synthesis and Characterization of Carbosilane Dendrimer−Sodium Montmorillonite Clay Nanocomposites. Experimental and Theoretical Studies.

    Czech Academy of Sciences Publication Activity Database

    Strašák, Tomáš; Malý, M.; Müllerová, M.; Čermák, Jan; Kormunda, M.; Čapková, P.; Matoušek, J.; Červenková Šťastná, Lucie; Rejnek, J.; Holubová, J.; Jandová, Věra; Čépe, K.

    2016-01-01

    Roč. 6, č. 49 (2016), s. 43356-43366 ISSN 2046-2069 Institutional support: RVO:67985858 Keywords : silicates * ionic liquids * molecular dynamics Subject RIV: CC - Organic Chemistry Impact factor: 3.108, year: 2016

  15. Effect of montmorillonite clay on flax fabric reinforced poly lactic acid composites with amphiphilic additives

    CSIR Research Space (South Africa)

    Kumar, R

    2010-01-01

    Full Text Available 5083263; fax: +27 41 5832325. Composites: Part A xxx (2010) xxx–xxx Contents lists availabl tes ev E-mail address: krrakesh72@gmail.com (R. Kumar). strength and stiffness, dimensional stability, and thermal proper- ties [1]. But finite nature.... Chemical treatments of natural fiber for use in natural fiber-reinforced composites: a review. J Polym Environ 2007;15:25–33. [15] Pothan LA, Thomas S, Groeninckx G. The role of fibre/matrix interactions on the dynamic mechanical properties...

  16. The Effect of a Rapid Heating Rate, Mechanical Vibration and Surfactant Chemistry on the Structure–Property Relationships of Epoxy/Clay Nanocomposites

    Directory of Open Access Journals (Sweden)

    Kevin Magniez

    2013-08-01

    Full Text Available The role of processing conditions and intercalant chemistry in montmorillonite clays on the dispersion, morphology and mechanical properties of two epoxy/clay nanocomposite systems was investigated in this paper. This work highlights the importance of employing complementary techniques (X-ray diffraction, small angle X-ray scattering, optical microscopy and transmission electron microscopy to correlate nanomorphology to macroscale properties. Materials were prepared using an out of autoclave manufacturing process equipped to generate rapid heating rates and mechanical vibration. The results suggested that the quaternary ammonium surfactant on C30B clay reacted with the epoxy during cure, while the primary ammonium surfactant (I.30E catalysed the polymerisation reaction. These effects led to important differences in nanocomposite clay morphologies. The use of mechanical vibration at 4 Hz prior to matrix gelation was found to facilitate clay dispersion and to reduce the area fraction of I.30E clay agglomerates in addition to increasing flexural strength by over 40%.

  17. Bentonite clay purification for development of polymeric nan composites using a single screw extruder; Purificacao de argila bentonita para desenvolvimento de nanocomposito polimerico utilizando uma extrusora rosca simples

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    In this work, a bentonite clay rich in montmorillonite was purified and chemical treat to be used in the development of poly (methyl methacrylate) /clay nanocomposites via melting processes. After the clay treatment and purification, a masterbatch with 25% clay and 75% PMMA was produced by solution technique, using acetone as solvent. For produce samples with 2.5% clay, the masterbatch along with pure polymer were added and mixed in single screw extruder with a diameter of 16 mm and W/D 26. X-rays diffractometry (XRD) and X-rays fluorescence (XRF). Tests were performed to evaluate and characterizing the bentonite clay used in the development of this work and differential scanning calorimetry (DSC) tests were performed to evaluate changes in the thermal properties of the nanocomposites produced. (author)

  18. The Effect of a Rapid Heating Rate, Mechanical Vibration and Surfactant Chemistry on the Structure–Property Relationships of Epoxy/Clay Nanocomposites

    Science.gov (United States)

    Nuhiji, Betime; Attard, Darren; Thorogood, Gordon; Hanley, Tracey; Magniez, Kevin; Bungur, Jenny; Fox, Bronwyn

    2013-01-01

    The role of processing conditions and intercalant chemistry in montmorillonite clays on the dispersion, morphology and mechanical properties of two epoxy/clay nanocomposite systems was investigated in this paper. This work highlights the importance of employing complementary techniques (X-ray diffraction, small angle X-ray scattering, optical microscopy and transmission electron microscopy) to correlate nanomorphology to macroscale properties. Materials were prepared using an out of autoclave manufacturing process equipped to generate rapid heating rates and mechanical vibration. The results suggested that the quaternary ammonium surfactant on C30B clay reacted with the epoxy during cure, while the primary ammonium surfactant (I.30E) catalysed the polymerisation reaction. These effects led to important differences in nanocomposite clay morphologies. The use of mechanical vibration at 4 Hz prior to matrix gelation was found to facilitate clay dispersion and to reduce the area fraction of I.30E clay agglomerates in addition to increasing flexural strength by over 40%. PMID:28811457

  19. The hydro- and multi-isotope geochemistry of iron-rich ground waters emerging at the southern Baltic Sea coast line

    Science.gov (United States)

    Lipka, Marko; Wu, Zijun; Escher, Peter; Struck, Ulrich; Dellwig, Olaf; Schafmeister, Maria; Böttcher*, Michael E.

    2013-04-01

    Iron-rich groundwater springs emerging at the shore zone of the southern Baltic Sea (BS; Site Meschendorf) were examined on a seasonal base for a period of about two years. Besides major, minor, and trace elements, stable isotopes of water (H-2, O-18), dissolved inorganic carbon (DIC; C-13), and sulfate (S-34) were analyzed. The stream bed sediment was extracted for the geochemistry of the newly formed precipitates and further characterized via SEM-EDAX. Subsequently, the hydrogeochemical results were subjected to a thermodynamic analysis via the PHREEQC speciation model. The springs emerge from small pits (about 60 cm diameter; up to 15cm depth). Surrounding sediments are sandy with gravels found at depth and corresponding high permeabilities. The positions of different springs on the shore zone were stable during the investigation period while the shape of the pits and the stream beds may vary due to wind- and wave-driven forces. Selected measurements of spring yield discharges close to 10 L/min. The H-2 and O-18 contents of the spring waters indicate the ground water to originate from relatively young mixed meteoric waters. The hydrochemistry of the springs was similar and showed some variability in between which indicates that the genetic processes for the ground water before reaching the surface may slightly differ. The springs are characterized by dissolved Ca, Mg, Na, DIC and sulfate, mainly reflecting the interaction with soils and bedrocks in the recharge area that is dominated by marly till. The oxygen-free ground water is rich in Fe, P, and DIC. Iron and dissolved sulfate originate from the oxidation of pyrite, as further confirmed by the 34-S signature of sulfate. The carbon isotope signature of DIC indicates a mixture of biogenic CO2 from the soil zone with some water-rock interaction with carbonate minerals. The streams flow towards the BS and, in contact with the atmosphere, outgas carbon dioxide and takes up oxygen. Upon CO2-degassing, C-12 is

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

    Directory of Open Access Journals (Sweden)

    M. A. Tolbert

    2007-08-01

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

  1. New approach to obtain elastomeric nano composites with clay from lattices;Nova metodologia para obtencao de nanocompositos elastomericos a partir de laticas comerciais e argila

    Energy Technology Data Exchange (ETDEWEB)

    Azeredo, Luciane K. de; Jacobi, Marly M., E-mail: jacobi@iq.ufrgs.b [Universidade Federal do Rio Grande do Sul (IQ/UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica. Programa de Pos-Graduacao em Materiais; Schuster, Robert H. [Deutches Institut fuer Kautschuktechnologie (DIK), Hannover (Germany)

    2009-07-01

    Rubber-Montmorillonite nanocomposites were prepared by Continuous Dynamic Latex Compounding (CDLC). This technique, recently developed in our laboratory, permits an intensive intercalation of the polymer at very small residence times in an elongational flow reactor. The processing conditions strongly affect the morphology of nanocomposites characterized by TEM and XRD. Clay-rubber nanocomposites were prepared from the mixture of NBR-, XNBR- and SBR-latex and aqueous suspensions of Na-montmorillonite. The polarity of rubbers influences the final properties of nanocomposites. The nanocomposites obtained by CDLC showed better reinforcement and permeation resistance at far less volume fractions than the obtained with carbon black or silica by conventional methods. (author)

  2. Fundamental investigations of clay/polymer nanocomposites and applications in co-extruded microlayered systems

    Science.gov (United States)

    Decker, Jeremy John

    The second and fourth generations of hydroxylated dendritic polyesters (HBP2, HBP4) were combined with unmodified sodium montmorillonite clay (Na +MMT) in water to generate a broad range of polymer clay nanocomposites from 0 to 100% wt/wt Na+MMT. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate intercalation states of the clay galleries. It was shown that interlayer spacings were independent of generation number and changed over the composition range from 0.5 nm to 3.5 nm in 0.5 nm increments that corresponded to a flattened HBP conformation within the clay tactoids. The HBP4/Na+MMT systems were investigated to study the vitrified Rigid Amorphous Fraction (RAF) induced by the clay surfaces. Differential Scanning Calorimetry (DSC) showed changes in heat capacity, Delta Cp, at Tg, that decreased with clay content, until completely suppressed at 80 wt% Na+MMT due to confinement. RAF was quantified from these changes in heat capacity and verified by the analysis of orthopositronium lifetime temperature scans utilizing positron annihilation lifetime spectroscopy (PALS): verifying the glassy nature of the RAF at elevated temperatures. Mathematical relationships allowed for correlation of the interlayer spacings with DeltaC p. RAF formation correlated to intercalated HBP4, and external surfaces of the clay tactoids. The interdiffusion of a polymer pair in microlayers was exploited to increase the concentration of nanoclay particles. When microlayers of a nanocomposite composed of organically modified montmorillonite (M2(HT)2 ) inside maleic anhydride grafted linear low-density polyethylene (LLDPE-g-MA) and low-density polyethylene (LDPE) were taken into the melt, the greater mobility of the linear LLDPE-g-MA chains compared to the branched LDPE chains caused shrinkage of the nanocomposite microlayers, concentrating the M 2(HT)2 contained within. Analysis of the clay morphology within these layers demonstrated an increase in clay

  3. 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…

  4. 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…

  5. Preparation of nanocomposites based on poly(Butylene Succinate) and montmorillonite organoclay via in situ polymerization; Preparo de nanocompositos de poli(succinato de butileno) (PDS) e argila motmorilonita organofilica via polimerizaco in situ

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Leticia P.; Moreira, Andrei N.; Souza Junior, Fernando G. de, E-mail: fgsj@ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Inst. de Macromoleculas; Pinto, Jose Carlos Costa da Silva [Coordenacao dos Cursos de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Quimica

    2014-09-15

    Nanocomposites based on poly(butylene succinate) (PBS) and organophilic montmorillonite were synthesized via in situ polymerization using three different clay compositions (4, 6 and 8 wt%). The products were characterized by several different techniques. X-ray diffraction was useful to confirm the increase of the interlayer spacing of the clay due to the presence of the polymer chains among layers. Thermal analysis indicated that the polymerization method chosen led to materials with lower thermal stability compared to the pure PBS, due to the difficulty of chain growth in the presence of the clay. Low-field NMR technique was used to assess clay dispersion in the polymer, with exfoliated structures predominating in the nanocomposites. (author)

  6. Influence of clay minerals on curcumin properties: Stability and singlet oxygen generation

    Science.gov (United States)

    Gonçalves, Joyce L. S.; Valandro, Silvano R.; Poli, Alessandra L.; Schmitt, Carla C.

    2017-09-01

    Curcumin (CUR) has showed promising photophysical properties regarding to biological and chemical sciences. However, the main barrier for those applications are their low solubility and stability in aqueous solution. The effects of two different clay minerals, the montmorillonite (SWy-2) and the Laponite RD (Lap) nanoclay, on the stabilization of Curcumin were investigated. Their effects were compared with two well-established environments (acidic and neutral aqueous media). CUR/clay hybrids were prepared using a simple and fast method, where CUR solution was added into clay suspensions, to obtain well dispersed hybrids in water. The degradation process of CUR and CUR/clays hybrids was investigated using UV-Vis spectroscopic. For both studied hybrids, the CUR degradation process was suppressed by the presence of the clay particles. Furthermore, the Lap showed a great stabilization effect than SWy-2. This behavior was due to the smaller particle size and higher exfoliation ability of Lap, providing a large surface for CUR adsorption compared to SWy-2. The degradation process of CUR solutions and CUR/clay hybrids was also studied in the presence of light. CUR photodegradation process was faster not only in the aqueous solution but also in the clay suspension compared to those studied in the dark. The presence of clay particles accelerated the photodegradation of CUR due to the products formation in the reactions between CUR and oxygen radicals. Our results showed that the singlet oxygen quantum yield (ΦΔ) of CUR were about 59% higher in the clay suspensions than CUR in aqueous solution. Therefore, the formation of CUR/clay hybrids, in particularly with Lap, suppressed the degradation in absence light of CUR and increased the singlet oxygen generation, which makes this hybrids of CUR/clay a promising material to enlarge the application of CUR in the biological sciences.

  7. Technological applications of organo-montmorillonites in the removal of pyrimethanil from water: adsorption/desorption and flocculation studies.

    Science.gov (United States)

    Flores, Federico M; Undabeytia, Tomas; Morillo, Esmeralda; Torres Sánchez, Rosa M

    2017-06-01

    Pyrimethanil (2-aniline-4, 6-dimethylpyrimidine, PRM) is used in fruit packing plants to control fungal infections and diseases. The effluents greatly polluted with this fungicide, as a point source contamination, need to be technologically treated for their regeneration before they reach water bodies. This work evaluates the use of organo-montmorillonites, synthetized in our laboratory, for their application in adsorption and coagulation/flocculation processes for the removal of PRM from water. The adsorption-desorption performance of PRM in a raw montmorillonite (Mt) and several organo-montmorillonites (organo-Mt) obtained by different amounts and types of exchanged surfactants (octadecyltrimethylammonium (ODTMA) and didodecyldimethylammonium (DDAB) bromides and benzyltrimethylammonium chloride (BTMA)) was studied. The PRM adsorption on raw Mt was assigned mainly to an interlayer occupancy, while hydrophobic interactions between PRM and the surfactants in the exchanged samples increased PRM adsorption, which was correlated with the surfactant loading. PRM desorption showed irreversible behavior in raw Mt, which changed to reversible for organo-Mt samples, and was also correlated with the increase of surfactant loading.Two of the organo-Mt with high surfactant loading (twice the CEC) were assayed for the removal of commercial PRM in coagulation/flocculation tests, and their performance was compared to that of the native clay (Mt). The use of the organo-Mt produced flocculation at a very low ratio (0.5 g L -1 ), whereas no flocculation was observed with Mt. These results proved the feasibility of the use of organo-Mt for the treatment of wastewater contaminated with PRM using a low organo-Mt/liquid ratio.

  8. 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.

  9. Effect of Sonification Time on Synthesisi and Corrosion Resistance of Epoxy-Clay Nanocomposite

    Directory of Open Access Journals (Sweden)

    Niloufar Bahrami Panah

    2016-09-01

    Full Text Available In recent years many research works have been carried out on anti-corrosive nanocomposites coatings containing mineral reinforcements. The most important criteria in these attempts are polymerization method and the type of matrix and reinforcement of nanocomposites. In this regard, the physical and mechanical properties of the polymers in which a small amount of filler is used can be improved. In this research, an epoxy-clay nanocomposite was synthesized by in-situ polymerization method using a resin matrix based on bisphenol-A type epoxy and montmorillonite clay (Closite 15A. The treatment was used at different ultrasonic stirring times to disperse 1-4 weight percentages of clay particles into the matrix. The structure of synthesized epoxy-clay nanocomposite was studied by scanning electron microscopy and X-ray diffraction techniques. The average size of clay particles was determined by X-ray diffraction measurement. Then, anti-corrosion properties of epoxy-clay coatings, prepared under different ultrasonic durations and applied on carbon steel panels, were investigated by Tafel and electrochemical impedance spectroscopy techniques. For this purpose, the carbon steel panels coated with these coatings were immersed in 3.5% sodium chloride solution and tested at different immersion times. The results indicated that a nanocomposite containing 1% clay, synthesized, stirred 60 min ultrasonically, produced smaller particle size, lower corrosion current density and higher coating corrosion resistance than the other composite formulations. This nanocomposite provided superior protection against corrosion in sodium chloride solution.

  10. Effect of clay content on morphology and processability of electrospun keratin/poly(lactic acid) nanofiber.

    Science.gov (United States)

    Isarankura Na Ayutthaya, Siriorn; Tanpichai, Supachok; Sangkhun, Weradesh; Wootthikanokkhan, Jatuphorn

    2016-04-01

    This research work has concerned the development of volatile organic compounds (VOCs) removal filters from biomaterials, based on keratin extracted from chicken feather waste and poly(lactic acid) (PLA) (50/50%w/w) blend. Clay (Na-montmorillonite) was also added to the blend solution prior to carrying out an electro-spinning process. The aim of this study was to investigate the effect of clay content on viscosity, conductivity, and morphology of the electrospun fibers. Scanning electron micrographs showed that smooth and bead-free fibers were obtained when clay content used was below 2 pph. XRD patterns of the electrospun fibers indicated that the clay was intercalated and exfoliated within the polymers matrix. Percentage crystallinity of keratin in the blend increased after adding the clay, as evidenced from FTIR spectra and DSC thermograms. Transmission electron micrographs revealed a kind of core-shell structure with clay being predominately resided within the keratin rich shell and at the interfacial region. Filtration performance of the electrospun keratin/PLA fibers, described in terms of pressure drop and its capability of removing methylene blue, were also explored. Overall, our results demonstrated that it was possible to improve process-ability, morphology and filtration efficiency of the electrospun keratin fibers by adding a suitable amount of clay. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Confinement of a nonionic surfactant membrane within a montmorillonite as a new way to prepare organoclay materials

    Energy Technology Data Exchange (ETDEWEB)

    Guegan, Regis, E-mail: regis.guegan@univ-orleans.fr [Universite d' Orleans (France); Giovanela, Marcelo [Universidade de Caxias do Sul (UCS), RS (Brazil)

    2016-11-15

    The aim of this study was to prepare and characterize a hybrid layered material (organoclay) with a Na-montmorillonite and the triethylene glycol mono-n-decyl ether (C{sub 10}E{sub 3} ) nonionic surfactant which forms a lamellar phase at room temperature. The synthesized organoclay was characterized by complementary techniques (Fourier transform infrared spectroscopy and X-ray diffraction). Experiments in conjunction with electron density analysis showed that a bilayer or membrane of C{sub 10}E{sub 3} was intercalated within the interlayer space of a naturally exchanged Na-montmorillonite. The intercalation of a bilayer of C{sub 10}E{sub 3} in a clay mineral offers new perspectives for the manufacturing of nanomaterials. While showing a hydrophobic surface and a large interlayer space value, the resulting organoclay preserves the compensating cations within the interlayer space allowing one to perform ion exchanges, making easier the intercalation of further organic molecules of important size with functional properties or for environmental purposes. (author)

  12. Flame Retardant Multilayered Coatings on Acrylic Fabrics Prepared by One-Step Deposition of Chitosan/Montmorillonite Complexes

    Directory of Open Access Journals (Sweden)

    Federico Carosio

    2018-06-01

    Full Text Available Multilayered coatings deposited using the layer-by-layer (LbL assembly technique have attracted great interest in recent years as a sustainable and efficient solution for conferring flame retardant properties to fabrics. The unique structure and interaction established upon the coating assembly are the key factors for successful flame retardant properties. In this study we aimed at the deposition of multilayered coatings comprising chitosan and montmorillonite with a LbL-like structure and interactions by the simple processing of compacted chitosan/montmorillonite complexes obtained by the direct mixing of an oppositely charged solution/suspension. Upon drying, the prepared complex yielded a continuous coating characterized by a brick-and-mortar multi-layered structure, in which oriented clay nanoplatelets were held together by a continuous chitosan matrix. When deposited on acrylic fabrics these coatings were able to suppress the melt-dripping phenomenon, and at 10 and 20% add-ons achieved self-extinguishing behavior within a few seconds after ignition. Cone calorimetry testing revealed an increase in time to ignition (up to +46% and considerable reductions of the rates at which heat is released (up to −62 and −49% for peak of heat release rate and total heat release, respectively. A reduction in the total smoke release (up to −49% was also observed.

  13. Preservation of glutamic acid-iron chelate into montmorillonite to efficiently degrade Reactive Blue 19 in a Fenton system under sunlight irradiation at neutral pH

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhujian [College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642 (China); Wu, Pingxiao, E-mail: pppxwu@scut.edu.cn [School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006 (China); Gong, Beini; Yang, Shanshan; Li, Hailing [School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Zhu, Ziao; Cui, Lihua [College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642 (China)

    2016-05-01

    Graphical abstract: - Highlights: • G–Fe chelate molecules were well preserved into montmorillonite. • The product shows an excellent catalytic activity under sunlight at neutral pH value. • G–Fe–Mt is a promising catalyst for advanced oxidation processes. - Abstract: To further enhance the visible light responsive property and the chemical stability of Fe/clay mineral catalysts, glutamic acid-iron chelate intercalated montmorillonite (G–Fe–Mt) was developed. The physiochemical properties of G–Fe–Mt were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), etc. The results showed that glutamic acid-iron chelates were successfully intercalated into the gallery of montmorillonite and the intercalated glutamic acid-iron chelate molecules were well preserved. The product G–Fe–Mt displayed excellent catalytic performance in heterogeneous photo-Fenton reaction under sunlight irradiation at acidic and neutral pH values. The chelation and the visible light responsiveness of glutamic acid produce a synergistic effect leading to greatly enhanced sunlight-Fenton reaction catalyzed by the heterogeneous G–Fe–Mt under neutral pH. G–Fe–Mt is a promising catalyst for advanced oxidation processes.

  14. Novel Montmorillonite/TiO2/MnAl-Mixed Oxide Composites Prepared from Inverse Microemulsions as Combustion Catalysts

    Directory of Open Access Journals (Sweden)

    Bogna D. Napruszewska

    2017-11-01

    Full Text Available A novel design of combustion catalysts is proposed, in which clay/TiO2/MnAl-mixed oxide composites are formed by intermixing exfoliated organo-montmorillonite with oxide precursors (hydrotalcite-like in the case of Mn-Al oxide obtained by an inverse microemulsion method. In order to assess the catalysts’ thermal stability, two calcination temperatures were employed: 450 and 600 °C. The composites were characterized with XRF (X-ray fluorescence, XRD (X-ray diffraction, HR SEM (high resolution scanning electron microscopy, N2 adsorption/desorption at −196 °C, and H2 TPR (temperature programmed reduction. Profound differences in structural, textural and redox properties of the materials were observed, depending on the presence of the TiO2 component, the type of neutralization agent used in the titania nanoparticles preparation (NaOH or NH3 (aq, and the temperature of calcination. Catalytic tests of toluene combustion revealed that the clay/TiO2/MnAl-mixed oxide composites prepared with the use of ammonia showed excellent activity, the composites obtained from MnAl hydrotalcite nanoparticles trapped between the organoclay layers were less active, but displayed spectacular thermal stability, while the clay/TiO2/MnAl-mixed oxide materials obtained with the aid of NaOH were least active. The observed patterns of catalytic activity bear a direct relation to the materials’ composition and their structural, textural, and redox properties.

  15. XRD study of intercalation in statically annealed composites of ethylene copolymers and organically modified montmorillonites. 2. One-tailed organoclays

    Directory of Open Access Journals (Sweden)

    Sara Filippi

    2014-01-01

    Full Text Available Ethylene copolymers with different polar comonomers, such as vinyl acetate, methyl acrylate, glycidyl methacrylate, and maleic anhydride, were used for the preparation of polymer/clay nanocomposites by statically annealing their mechanical mixtures with different commercial or home-made organically modified montmorillonites containing only one long alkyl tail. The nanostructure of the products was monitored by X-ray diffraction, and the dispersion of the silicate particles within the polymer matrix was qualitatively evaluated through microscopic analyses. The effect of the preparation conditions on the structure and the morphology of the composites was also addressed through the characterization of selected samples with similar composition prepared by melt compounding. In agreement with the findings reported in a previous paper for the composites filled with two-tailed organoclays, intercalation of the copolymer chains within the tighter galleries of the one-tailed clays occurs easily, independent of the application of a mechanical stress. However, the shear-driven break-up of the intercalated clay particles into smaller platelets (exfoliation seems more hindered. A collapse of the organoclay interlayer spacing was only observed clearly for a commercial one-tailed organoclay – Cloisite® 30B – whereas the same effect was almost negligible for a home-made organoclay with similar structure.

  16. Novel Montmorillonite/TiO₂/MnAl-Mixed Oxide Composites Prepared from Inverse Microemulsions as Combustion Catalysts.

    Science.gov (United States)

    Napruszewska, Bogna D; Michalik-Zym, Alicja; Rogowska, Melania; Bielańska, Elżbieta; Rojek, Wojciech; Gaweł, Adam; Wójcik-Bania, Monika; Bahranowski, Krzysztof; Serwicka, Ewa M

    2017-11-19

    A novel design of combustion catalysts is proposed, in which clay/TiO₂/MnAl-mixed oxide composites are formed by intermixing exfoliated organo-montmorillonite with oxide precursors (hydrotalcite-like in the case of Mn-Al oxide) obtained by an inverse microemulsion method. In order to assess the catalysts' thermal stability, two calcination temperatures were employed: 450 and 600 °C. The composites were characterized with XRF (X-ray fluorescence), XRD (X-ray diffraction), HR SEM (high resolution scanning electron microscopy, N₂ adsorption/desorption at -196 °C, and H₂ TPR (temperature programmed reduction). Profound differences in structural, textural and redox properties of the materials were observed, depending on the presence of the TiO₂ component, the type of neutralization agent used in the titania nanoparticles preparation (NaOH or NH₃ (aq)), and the temperature of calcination. Catalytic tests of toluene combustion revealed that the clay/TiO₂/MnAl-mixed oxide composites prepared with the use of ammonia showed excellent activity, the composites obtained from MnAl hydrotalcite nanoparticles trapped between the organoclay layers were less active, but displayed spectacular thermal stability, while the clay/TiO₂/MnAl-mixed oxide materials obtained with the aid of NaOH were least active. The observed patterns of catalytic activity bear a direct relation to the materials' composition and their structural, textural, and redox properties.

  17. Development of nanocomposites employing high-density polyethylene and organo clay

    International Nuclear Information System (INIS)

    Lessa, Tathiane C. Rodrigues F.; Tavares, Maria Ines B.; Pita, Vitor J.R.R.

    2009-01-01

    The purpose of this study was to prepare nanocomposites of high-density polyethylene and montmorillonite organoclay by polymer melt intercalation, employing different processing parameters. Effective clay incorporation into polyethylene matrix was observed. The nanocomposites were structurally characterized. Intercalated nanocomposites were obtained from different process parameters, employing polyethylene resin and montmorillonite organoclays. The XRD results and other analysis showed that the processing parameters affect the organoclay delamination. The polyethylene nanocomposite presented the better performance using twin screw extruder, at 90 rpm. The purpose of characterization of polyethylene/organoclay nanocomposite by low-field NMR showed that this technique was important to understand changes in the molecular mobility of polyethylene when organoclay was incorporated. (author)

  18. Characterization of sands and mineral clays in channel and floodplain deposits of Portuguesa river, Venezuela

    Directory of Open Access Journals (Sweden)

    Orlando José González Clemente

    2013-11-01

    Full Text Available In the main channel and floodplain of Portuguesa River were studied the mineralogical characteristics of sand and clay minerals respectively. The methodology consisted of X-ray diffraction (XRD analysis, for both mineral fractions. The results indicated the presence of mainly of quartz sands with minor amounts of chlorite, muscovite, calcite and feldspar which are considered quartz sand mature. Its origin is related to the source area and rework of soils and sediments of the floodplain. The clay fraction is characterized by the presence of 13 mineral crystalline phases consisting mainly of quartz, muscovite and chlorite, and clay minerals such as kaolinite, vermiculite, montmorillonite and nontronita. Its detrital origin may be due to mineral neoformation and inheritance. Therefore both mineral fractions consist mainly of quartz and kaolinite, which are essential components of the source area as well as the Quaternary alluvial deposits and the soils that make up the region.

  19. Analysis and characterization of kaolinitic clay Rio Grande do Norte for use in refractory

    International Nuclear Information System (INIS)

    Medeiros, A.L.; Souza Junior, C.F.; Silva, C.L. Mendes da

    2011-01-01

    This work aims to characterize clays from the State of Rio Grande do Norte for use in the manufacture of refractory bricks. Initially, we analyzed the X-ray fluorescence and X-ray diffraction on samples of clay to obtain the components of the starting materials and their microstructures. The test samples were fabricated by uniaxial pressure of 20 MPa, and then were sintered between 1000 ° C and 1200 ° C, with a landing sintering for 1 hour. Tests including thermal shrinkage, water absorption and apparent porosity. Initial results of the analysis indicate the presence of clay minerals kaolinite, montmorillonite and muscovite, as well group minerals of quartz, dolomite, calcite and calcium silicate in the samples tested. (author)

  20. Kinetic Study of Denatonium Sorption to Smectite Clay Minerals.

    Science.gov (United States)

    Crosson, Garry S; Sandmann, Emily

    2013-06-01

    The denatonium cation, as a benzoate salt, is the most bitter cation known to modern society and is frequently added to consumer products to reduce accidental and intentional consumption by humans and animals. Denatonium can enter the environment by accidental discharges, potentially rendering water supplies undrinkable. Interactions of denatonium with soil components ( i.e. , smectite minerals) ultimately control the environmental fate of denatonium, but the current literature is devoid of studies that evaluate denatonium sorption to smectite minerals. This study investigated the mechanism and kinetics of denatonium sorption to smectite clay minerals as a function of smectite type, temperature, pH and ionic strength. Uptake by synthetic mica montmorillonite (Syn-1), Wyoming montmorillonite (SWy-2), and Texas montmorillonite (STx-1b) at 305K was rapid, with equilibrium being reached within 2 min for all clays. Complete removal of denatonium was observed for STx-1b at pH 6.9, while partial removal was observed for Syn-1 and SWy-2. Kinetic behavior of SWy-2 and Syn-1 is consistent with a pseudo-second-order model at 305K. An activation energy of +25.9 kJ/mol was obtained for sorption to Syn-1 and was independent of temperature between 286K and 338K. Activation-free energy (Δ G *), activation enthalpy (Δ H *), and activation entropy (Δ S *) for Syn-1 were found to be +62.91 kJ/mol, +23.36 kJ/mol, and -0.130 kJ/(K·mol), respectively. Sorption capacities at pH 3.6, 6.9, and 8.2 were constant at 1.3×10 -2 g denatonium/g clay; however, the kinetic rate constant increased by 56%, going from acidic to basic solution conditions. Distribution coefficients were negatively correlated with ionic strength, suggesting cation exchange. Collectively, results suggested that smectite minerals can serve as efficient sinks for denatonium cations. This is much-needed information for agencies developing regulations regarding denatonium usage and for water treatment professionals

  1. Color measurement of methylene blue dye/clay mixtures and its application using economical methods

    Science.gov (United States)

    Milosevic, Maja; Kaludjerovic, Lazar; Logar, Mihovil

    2016-04-01

    Identifying the clay mineral components of clay materials by staining tests is rapid and simple, but their applicability is restricted because of the mutual interference of the common components of clay materials and difficulties in color determination. The change of color with concentration of the dye is related to the use of colorants as a field test for identifying clay minerals and has been improved over the years to assure the accuracy of the tests (Faust G. T., 1940). The problem of measurement and standardization of color may be solved by combination of colors observed in staining tests with prepared charts of color chips available in the Munsell Book of Color, published by Munsell Color Co. Under a particular set of illumination conditions, a human eye can achieve an approximate match between the color of the dyed clay sample and that of a standard color chip, even though they do have different spectral reflectance characteristics. Experiments were carried out with diffuse reflectance spectroscopy on selected clay samples (three montmorillonite, three kaolinite and one mix-layer clay samples) saturated with different concentration of methylene blue dye solution. Dominant wavelength and purity of the color was obtained on oriented dry samples and calculated by use of the I. C. I. (x, y) - diagram in the region of 400-700 nm (reflectance spectra) without MB and after saturation with different concentrations of MB solutions. Samples were carefully photographed in the natural light environment and processed with user friendly and easily accessible applications (Adobe color CC and ColorHexa encyclopedia) available for android phones or tablets. Obtained colors were compared with Munsell standard color chips, RGB and Hexa color standards. Changes in the color of clay samples in their interaction with different concentration of the applied dye together with application of economical methods can still be used as a rapid fieldwork test. Different types of clay

  2. Characterization of clay minerals

    International Nuclear Information System (INIS)

    Diaz N, C.; Olguin, M.T.; Solache R, M.; Alarcon H, T.; Aguilar E, A.

    2002-01-01

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

  3. Hybrid structures based on montmorillonite/modified starch intercalate

    Czech Academy of Sciences Publication Activity Database

    Duchek, P.; Špírková, Milena

    2010-01-01

    Roč. 104, č. 9 (2010), s. 885 ISSN 0009-2770. [International Conference on Polysaccharides-Glycoscience /6./. 29.09.2010-1.10.2010, Praha] R&D Projects: GA AV ČR(CZ) IAAX08240901 Institutional research plan: CEZ:AV0Z40500505 Keywords : organic/inorganic hybrides * montmorillonite Subject RIV: JI - Composite Materials

  4. Different level of fluorescence in Raman spectra of montmorillonites

    Czech Academy of Sciences Publication Activity Database

    Ritz, M.; Vaculíková, Lenka; Kupková, J.; Plevová, Eva; Bartoňová, L.

    2016-01-01

    Roč. 84, May 2016 (2016), s. 7-15 ISSN 0924-2031 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : Raman spectroscopy * fluorescence * montmorillonite Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.740, year: 2016

  5. Homoionic inorganic montmorillonites as fillers for Polyamide 6 nanocomposites

    Czech Academy of Sciences Publication Activity Database

    Kadlecová, Z.; Puffr, Rudolf; Baldrian, Josef; Schmidt, Pavel; Roda, J.; Brožek, J.

    2008-01-01

    Roč. 44, č. 9 (2008), s. 2798-2806 ISSN 0014-3057 Institutional research plan: CEZ:AV0Z40500505 Keywords : poly(.epsilon.-caprolactam) nanocomposite * calcium and magnesium montmorillonites * WAX analysis Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.143, year: 2008

  6. Improvement in tensile properties of PVC–montmorillonite ...

    Indian Academy of Sciences (India)

    mechanical properties of PVC–montmorillonite materials are also currently of huge ... Its hard form can withstand a tensile stress in the order of 46–52 MPa before .... 2θ at 25 mA and 40 kV using Cu-Kα radiation. X-ray diffraction patterns of the ...

  7. Processing and properties of polyethylene/montmorillonite nanocomposites

    Czech Academy of Sciences Publication Activity Database

    Měřínská, D.; Kubisova, H.; Kalendová, A.; Svoboda, P.; Hromádková, Jiřina

    2012-01-01

    Roč. 25, č. 1 (2012), s. 115-131 ISSN 0892-7057 Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer nanocomposite * montmorillonite * polyethylene Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.750, year: 2012

  8. Morphological analysis of thermoplastic starch films and montmorillonite (TPS/MMT) using vegetable oils of Brazilian Cerrado as plasticizers

    International Nuclear Information System (INIS)

    Schlemmer, Daniela; Sales, Maria Jose A.; Angelica, Romulo S.; Gomes, Ana Cristina M.M.

    2009-01-01

    Biopolymers can be used where petrochemical plastics have applications with short life. The excellent degradation of starch and its low cost make it an alternative for obtaining biodegradable plastics. To obtain thermoplastic starch (TPS) is necessary mechanical shake, high temperature and plasticizers. In this work, TPS were produced using three different vegetable oils from Brazilian's cerrado as plasticizers: buriti, macauba or pequi. Materials are also produced with montmorillonite (MMT). All the materials were analyzed by scanning electronic microscopy (SEM) and X-ray diffraction (XRD). The starch micrographs revealed irregular delaminate with a predominance of starch and 'holes' for the oils. In nanocomposites the clusters of clay are dispersed without a defined standard. It was understood that the plasticizers and processing completely changed the structure of starch causing a decrease in their crystallinity degree. Almost all nanocomposites presented exfoliate structure, only one presented intercalated structure. (author)

  9. Detailed mineralogical characterization of the Bullfrog and Tram members USW-G1, with emphasis on clay mineralogy

    International Nuclear Information System (INIS)

    Bish, D.L.

    1981-10-01

    The detailed mineralogy of the Bullfrog and Tram Members of the Crater Flat Tuff from drill hole USW-G1 has been examined, primarily to characterize fully the amounts and types of clay minerals in the tuffs and the possible effects clay minerals have on rock properties. Results of bulk sample x-ray diffraction analyses agree closely with previous determinations, although slightly higher clay mineral contents were found in this study. X-ray diffraction analysis of fine fractions revealed that the clay minerals in the tuffs are sodium-saturated montmorillonite-beidellites with typical layer charges and no high-charge layers. These smectites are found in virtually all samples of the Bullfrog and Tram, and there is no correlation between the amounts of smectites and the amounts of zeolite, quartz, and feldspar. Smectites are present in both welded and nonwelded horizons and are scarce in some zones with slight-to-absent welding

  10. Synthesis and characterization of nanocomposites based on polyurethane in aqueous dispersions with non-modified hydrophilic clays

    International Nuclear Information System (INIS)

    Miranda, G.S.; Delpechi, M.C.; Santo, W.L.E.

    2010-01-01

    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)

  11. Modeling uranium(VI) adsorption onto montmorillonite under varying carbonate concentrations: A surface complexation model accounting for the spillover effect on surface potential

    Science.gov (United States)

    Tournassat, C.; Tinnacher, R. M.; Grangeon, S.; Davis, J. A.

    2018-01-01

    The prediction of U(VI) adsorption onto montmorillonite clay is confounded by the complexities of: (1) the montmorillonite structure in terms of adsorption sites on basal and edge surfaces, and the complex interactions between the electrical double layers at these surfaces, and (2) U(VI) solution speciation, which can include cationic, anionic and neutral species. Previous U(VI)-montmorillonite adsorption and modeling studies have typically expanded classical surface complexation modeling approaches, initially developed for simple oxides, to include both cation exchange and surface complexation reactions. However, previous models have not taken into account the unique characteristics of electrostatic surface potentials that occur at montmorillonite edge sites, where the electrostatic surface potential of basal plane cation exchange sites influences the surface potential of neighboring edge sites ('spillover' effect). A series of U(VI) - Na-montmorillonite batch adsorption experiments was conducted as a function of pH, with variable U(VI), Ca, and dissolved carbonate concentrations. Based on the experimental data, a new type of surface complexation model (SCM) was developed for montmorillonite, that specifically accounts for the spillover effect using the edge surface speciation model by Tournassat et al. (2016a). The SCM allows for a prediction of U(VI) adsorption under varying chemical conditions with a minimum number of fitting parameters, not only for our own experimental results, but also for a number of published data sets. The model agreed well with many of these datasets without introducing a second site type or including the formation of ternary U(VI)-carbonato surface complexes. The model predictions were greatly impacted by utilizing analytical measurements of dissolved inorganic carbon (DIC) concentrations in individual sample solutions rather than assuming solution equilibration with a specific partial pressure of CO2, even when the gas phase was

  12. Preparation and characterization of electronically conducting polypyrrole-montmorillonite nanocomposite and its potential application as a cathode material for oxygen reduction

    International Nuclear Information System (INIS)

    Rajapakse, R.M.G.; Murakami, Kenji; Bandara, H.M.N.; Rajapakse, R.M.M.Y.; Velauthamurti, K.; Wijeratne, S.

    2010-01-01

    Simple wet chemical processes were deployed to prepare low-cost conducting nanocomposites based on natural clays with 2:1 layered structures such as sodium montmorillonite (MMT). Ce(IV) modified MMT was used for the spontaneous polymerization of pyrrole within clay interlayers. The resulted clay-conducting polypyrrole nanocomposites containing the reduced form of the oxidising agent, have been extensively characterized by X-ray diffraction (XRD) technique for interlayer spacing variations and by Fourier transform infra red (FT-IR) spectroscopy to study the interactions between the clay and polymer functional groups. DC polarization technique with both blocking and non-blocking electrodes was used to distinguish between the ionic and electronic transport numbers and to recognize the type of mobile ionic species. AC impedance analysis further resolved the electrical conduction of these materials. Bulk conductivity analysis implied that the polypyrrole (PPY) formed within Ce(IV) modified MMT posses dominant electronic conductivity. The low-cost, light-weight and stable polymer-clay nanocomposite prepared by Ce(IV) intercalated MMT, [Ce(III)-PPY-MMT], seems to be a promising cathode material for oxygen reduction and hence may find applications in fuel cell industries.

  13. Adsorption of acetanilide herbicides on soil and its components. II. Adsorption and catalytic hydrolysis of diethatyl-ethyl on saturated Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite.

    Science.gov (United States)

    Liu, W P; Fang, Z; Liu, H J; Yang, W C

    2001-04-01

    Adsorption and catalytic hydrolysis of the herbicide diethatyl-ethyl [N-chloroacetyl-N-(2,6-diethylphenyl)glycine ethyl ester] on homoionic Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite clays were investigated in water solution. The Freundlich adsorption coefficient, Ki, got from isotherms on clay followed the order of Na+ approximately K+ > Mg2+ approximately Ca2+. Analysis of FT-IR spectra of diethatyl-ethyl adsorbed on clay suggests probable bonding at the carboxyl and amide carbonyl groups of the herbicide. The rate of herbicide hydrolysis in homoionic clay suspensions followed the same order as that for adsorption, indicating that adsorption may have preceded and thus caused hydrolysis. Preliminary product identification showed that hydrolysis occurred via nucleophilic substitution at the carboxyl carbon, causing the cleavage of the ester bond and formation of diethatyl and its dechlorinated derivative, and at the amide carbon, yielding an ethyl ester derivative and its acid. These pathways also suggest that hydrolysis of diethatyl-ethyl was catalyzed by adsorption on the clay surface.

  14. Experimental investigation of virus and clay particles cotransport in partially saturated columns packed with glass beads.

    Science.gov (United States)

    Syngouna, Vasiliki I; Chrysikopoulos, Constantinos V

    2015-02-15

    Suspended clay particles in groundwater can play a significant role as carriers of viruses, because, depending on the physicochemical conditions, clay particles may facilitate or hinder the mobility of viruses. This experimental study examines the effects of clay colloids on the transport of viruses in variably saturated porous media. All cotransport experiments were conducted in both saturated and partially saturated columns packed with glass beads, using bacteriophages MS2 and ΦX174 as model viruses, and kaolinite (KGa-1b) and montmorillonite (STx-1b) as model clay colloids. The various experimental collision efficiencies were determined using the classical colloid filtration theory. The experimental data indicated that the mass recovery of viruses and clay colloids decreased as the water saturation decreased. Temporal moments of the various breakthrough concentrations collected, suggested that the presence of clays significantly influenced virus transport and irreversible deposition onto glass beads. The mass recovery of both viruses, based on total effluent virus concentrations, was shown to reduce in the presence of suspended clay particles. Furthermore, the transport of suspended virus and clay-virus particles was retarded, compared to the conservative tracer. Under unsaturated conditions both clay particles facilitated the transport of ΦX174, while hindered the transport of MS2. Moreover, the surface properties of viruses, clays and glass beads were employed for the construction of classical DLVO and capillary potential energy profiles, and the results suggested that capillary forces play a significant role on colloid retention. It was estimated that the capillary potential energy of MS2 is lower than that of ΦX174, and the capillary potential energy of KGa-1b is lower than that of STx-1b, assuming that the protrusion distance through the water film is the same for each pair of particles. Moreover, the capillary potential energy is several orders of

  15. Thermodynamic of hydration of a Wyoming montmorillonite saturated with Ca, Mg, Na and K

    International Nuclear Information System (INIS)

    Vieillard, P.; Blanc, P.; Gailhanou, H.; Gaboreau, S.; Giffaut, E.

    2010-01-01

    enthalpy of immersion, and isotherms of adsorption - desorption has been done for Wyoming montmorillonite saturated by Mg 2+ , Ca 2+ , Na + and K + . Smectite water-vapor pressure isotherms represent the total concentration of H 2 O taken up the sample which is distributed among the interlayers, the outer surfaces of particles and the open pore space in the sample. In order to retrieve standard state thermodynamic properties for smectite hydration and dehydration from such data, the amount of H 2 O in excess of that in the interlayer must be assessed and subtracted from the total amount taken up by the clay sample. Berend et al. (1995), Cases et al. (1992, 1997) provide careful measurements of recovering waters in both processes (hydration and dehydration) on Wyoming saturated by monovalent and divalent cations. Despite the fact that neither the hydration, nor the dehydration isotherm necessarily represents the equilibrium state of the system, the two isotherms together can be considered to bracket the equilibrium values of Xhs and the activity of H 2 O. Paired hydration and dehydration isotherm in the one hand and enthalpy of immersion in the other hand, which constitute the limits of these brackets can be regressed to assess standard state thermodynamic parameters (enthalpy and entropy) for the hydration- dehydration process. Experimental enthalpies of hydration are used in the determination of ΔH deg. hyd. W H1 and W H2 by the minimization technique. For the adsorption-desorption isotherms, the determination of parameters ΔS deg. hyd. W S1 and W S2 are obtained by minimizing the difference between measured sets of data (relative humidity and number of adsorbed interlayer water) and calculated ones. For each Wyoming saturated with one cation, six parameters are requested and characterize the standard state thermodynamic properties of hydration between smectite and interlayer H 2 O. Relations between hydration parameters ΔH deg. hyd. and ΔS deg. hyd. in the one hand

  16. Adsorption of Cs+, Ni2+ and lanthanides onto a kaolinite and Na-montmorillonite up to 1500C: an experimental and modeling study

    International Nuclear Information System (INIS)

    Tertre, E.

    2005-10-01

    The motivation for this study is to assess the temperature effect on the clay minerals sorption properties. Sorption and desorption of Cs + , Ni 2+ et Ln 3+ onto a montmorillonite and a kaolinite were performed by batch experiments between 25 and 150 C, and in different pH and ionic strengths conditions. Sorption enthalpies varying between 0 and 80 kJ/mol were then calculated. For europium, surface spectroscopic analyses confirmed that the mechanism involved is adsorption, including at 150 C. Moreover, this method allowed us to obtain qualitatively the different adsorption equilibrium occurring during the reaction. An acid/base study of the clay surfaces was performed in order to assess the temperature effect on the surface charge of these minerals. Then, a surface complexation model including edge sites and structural sites was proposed to interpret the acid/base data and the europium sorption data. (author)

  17. Dynamics of water confined in clay minerals

    International Nuclear Information System (INIS)

    Le Caer, S.; Pommeret, S.; Renault, J.Ph.; Lima, M.; Righini, R.; Gosset, D.; Simeone, D.; Bergaya, F.

    2012-01-01

    Ultrafast infrared spectroscopy of the O-D stretching mode of dilute HOD in H 2 O probes the local environment and the hydrogen bond network of confined water. The dynamics of water molecules confined in the interlayer space of montmorillonites (Mt) and in interaction with two types of cations (Li + and Ca 2+ ) but also with the negatively charged siloxane surface are studied. The results evidence that the OD vibrational dynamics is significantly slowed down in confined media: it goes from 1.7 ps in neat water to 2.6 Ps in the case of Li + cations with two water pseudo-layers (2.2-2.3 ps in the case of Ca 2+ cations) and to 4.7 ps in the case of Li + cations with one water pseudo-layer. No significant difference between the two cations is noticed. In this 2D confined geometry (the interlayer space being about 0.6 nm for two water pseudo-layers), the relaxation time constants obtained are comparable to the ones measured in analogous concentrated salt solutions. Nevertheless, and in strong opposition to the observations performed in the liquid phase, anisotropy experiments evidence the absence of rotational motions on a 5 ps time scale, proving that the hydrogen bond network in the interlayer space of the clay mineral is locked at this time scale. (authors)

  18. Sorption and direct speciation of neptunium(V) on aluminium oxide and montmorillonite

    International Nuclear Information System (INIS)

    Wendt, Sonja

    2009-01-01

    -1 at high pH were O ax ∼ 1.84 Aa and O eq ∼ 2.53 Aa. At high pH, ternary neptunyl carbonate surface complexes could be identified for montmorillonite (C ∼ 3.00 Aa), but not for γ-Al 2 O 3 , where an interaction of neptunium with the aluminium surface atoms according to the soddyite model gave better agreement with the experimental data. However, neither structure as suggested by the two models could be excluded for both systems rendering a combination most likely. Modelling of the sorption data provided further evidence for the existence of ternary neptunium carbonate surface complexes in both cases. The results of this study can aid environmental risk assessment for clay-based nuclear waste repositories by providing valuable input data for simulations of radionuclide migration from a final disposal site.

  19. Study of the Effect of Clay Particles on Low Salinity Water Injection in Sandstone Reservoirs

    Directory of Open Access Journals (Sweden)

    Sina Rezaei Gomari

    2017-03-01

    Full Text Available The need for optimal recovery of crude oil from sandstone and carbonate reservoirs around the world has never been greater for the petroleum industry. Water-flooding has been applied to the supplement primary depletion process or as a separate secondary recovery method. Low salinity water injection is a relatively new method that involves injecting low salinity brines at high pressure similar to conventional water-flooding techniques, in order to recover crude oil. The effectiveness of low salinity water injection in sandstone reservoirs depends on a number of parameters such as reservoir temperature, pressure, type of clay particle and salinity of injected brine. Clay particles present on reservoir rock surfaces adsorb polar components of oil and modify wettability of sandstone rocks to the oil-wet state, which is accountable for the reduced recovery rates by conventional water-flooding. The extent of wettability alteration caused by three low salinity brines on oil-wet sandstone samples containing varying clay content (15% or 30% and type of clay (kaolinite/montmorillonite were analyzed in the laboratory experiment. Contact angles of mica powder and clay mixture (kaolinite/montmorillonite modified with crude oil were measured before and after injection with three low salinity sodium chloride brines. The effect of temperature was also analyzed for each sample. The results of the experiment indicate that samples with kaolinite clay tend to produce higher contact angles than samples with montmorillonite clay when modified with crude oil. The highest degree or extent of wettability alteration from oil-wet to intermediate-wet state upon injection with low salinity brines was observed for samples injected with brine having salinity concentration of 2000 ppm. The increase in temperature tends to produce contact angles values lying in the higher end of the intermediate-wet range (75°–115° for samples treated at 50 °C, while their corresponding

  20. Large scale structures in liquid crystal/clay colloids

    Science.gov (United States)

    van Duijneveldt, Jeroen S.; Klein, Susanne; Leach, Edward; Pizzey, Claire; Richardson, Robert M.

    2005-04-01

    Suspensions of three different clays in K15, a thermotropic liquid crystal, have been studied by optical microscopy and small angle x-ray scattering. The three clays were claytone AF, a surface treated natural montmorillonite, laponite RD, a synthetic hectorite, and mined sepiolite. The claytone and laponite were sterically stabilized whereas sepiolite formed a relatively stable suspension in K15 without any surface treatment. Micrographs of the different suspensions revealed that all three suspensions contained large scale structures. The nature of these aggregates was investigated using small angle x-ray scattering. For the clays with sheet-like particles, claytone and laponite, the flocs contain a mixture of stacked and single platelets. The basal spacing in the stacks was independent of particle concentration in the suspension and the phase of the solvent. The number of platelets in the stack and their percentage in the suspension varied with concentration and the aspect ratio of the platelets. The lath shaped sepiolite did not show any tendency to organize into ordered structures. Here the aggregates are networks of randomly oriented single rods.

  1. Large scale structures in liquid crystal/clay colloids

    International Nuclear Information System (INIS)

    Duijneveldt, Jeroen S van; Klein, Susanne; Leach, Edward; Pizzey, Claire; Richardson, Robert M

    2005-01-01

    Suspensions of three different clays in K15, a thermotropic liquid crystal, have been studied by optical microscopy and small angle x-ray scattering. The three clays were claytone AF, a surface treated natural montmorillonite, laponite RD, a synthetic hectorite, and mined sepiolite. The claytone and laponite were sterically stabilized whereas sepiolite formed a relatively stable suspension in K15 without any surface treatment. Micrographs of the different suspensions revealed that all three suspensions contained large scale structures. The nature of these aggregates was investigated using small angle x-ray scattering. For the clays with sheet-like particles, claytone and laponite, the flocs contain a mixture of stacked and single platelets. The basal spacing in the stacks was independent of particle concentration in the suspension and the phase of the solvent. The number of platelets in the stack and their percentage in the suspension varied with concentration and the aspect ratio of the platelets. The lath shaped sepiolite did not show any tendency to organize into ordered structures. Here the aggregates are networks of randomly oriented single rods

  2. Enrofloxacin uptake and retention on different types of clays

    Science.gov (United States)

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

    2013-11-01

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

  3. Estimation of bitumen and clay content in fine tailings

    International Nuclear Information System (INIS)

    Motta Cabrera, S.C.; Bryan, J.; Kantzas, A.

    2007-01-01

    Fine tailings are the components of tailings ponds and the by-product of the oil sand extraction process, consisting mostly of water with small amounts of bitumen, sand, silts and clays. Because of the large volumes of tailings, an important environmental and production process issue involves the reduction of the remaining bitumen in the tailings stream. This paper presented the results of a study that used low field nuclear magnetic resonance (NMR) in order to estimate the bitumen, clay and water content of synthetic tailings samples. NMR is a non-destructive technique that is utilized to determine compositions of oil and brine emulsions and the viscosity of heavy oil and bitumen as well as in reservoir characterization, measuring properties such as permeability, porosity, mobile and immobile fluids, and fluid saturations. The study prepared and tested numerous samples with variable water, bitumen, sand and clay concentrations in the NMR tool under ambient conditions. Two qualities of water and bitumen were used to prepare the synthetic samples. Each type of water and bitumen was analyzed as a single substance and in a mixture with the typical solids found in tailings composition. These included kaolinite, illite, sodium montmorillonite and sand. These synthetic samples were analyzed using different mixing configurations, as a function of time and in two different NMR tools. It was concluded that NMR is a potential application for on-line determination of tailings streams composition. 18 refs., 3 tabs., 17 figs

  4. Clay based polymeric composites: Preparation and quality characterization

    International Nuclear Information System (INIS)

    Aloisi, G.G.; Elisei, F.; Nocchetti, M.; Camino, G.; Frache, A.; Costantino, U.; Latterini, L.

    2010-01-01

    Commercial clays Cloisites Na + , 30B and 20A were labelled with the fluorescent dye Rhodamine B and used as fillers of polypropylene in order to prepare composites to be studied with confocal fluorescence microscopy. The dye uptake by clays was monitored by X-ray powder diffraction and spectroscopic analyses and clear evidences of intercalated dye in the organically modified montmorillonites Clo30B and Clo20A were obtained. Clay-Rhodamine B hybrids were investigated by steady-state absorption and emission spectroscopy to explore the effect of dye arrangement on the optical properties. The obtained information was used to rationalize fluorescence behaviour of composites. Confocal fluorescence imaging gave rise to bright fluorescent images of Cloisite aggregated labelled with the dye allowing to easily and directly visualize the 3-D dispersion of the labelled fillers in the polymer matrix in a non-invasive manner. The images were analyzed in terms of size distribution of the fluorescence grains to quantify the dispersion degree. The data indicate that Clo20A is able to homogeneously distribute in the polymer matrix forming a composite material.

  5. Trace Cd(II, Pb(II and Ni(II ions extraction and preconcentration from different water samples by using Ghezeljeh montmorillonite nanoclay as a natural new adsorbent

    Directory of Open Access Journals (Sweden)

    Zahra hassanzadeh Siahpoosh

    2017-01-01

    Full Text Available This investigate presents the extraction-preconcentration of Lead, Cadmium, and Nickel ions from water samples using Ghezeljeh montmorillonite nanoclay or “Geleh-Sar-Shoor” (means head-washing clay as a natural and native new adsorbent in batch single element systems. The Ghezeljeh clay is categorized by using Fourier Transform Infrared Spectroscopy (FT-IR, Scanning Electron Microscopy-Energy Dispersive Spectrometer Operating (SEM-EDS, X-ray Diffractometry (XRD, X-ray Fluorescence (XRF, Cation Exchange Capacity (CEC measurements, Surface property valuation (SBET by the BET method from nitrogen adsorption isotherms and Zeta potential. According to BET theory, the specific surface area of Ghezeljeh nanoclay was computed as 19.8 m2 g-1 whereas the cation exchange capacity was determined as 150 meq (100 g-1. The results of XRD, FT-IR, XRF, zeta potential, BET surface area and CEC of the Ghezeljeh clay confirm that montmorillonite is the dominant mineral phase. Based on SEM images of clay, it can be seen that the distance between the plates is nm level. For all three ions, the limit of detection, the limit of quantification, dynamic linear range, preconcentration factor, and the adsorption capacity were obtained. The result of several interfering ions was considered. The Ghezeljeh nanoclay as a new adsorbent and experimental method were effectively used for the extraction of heavy metals (Lead, Cadmium, and Nickel in a variety of real water samples.

  6. Simulation of the long term alteration of clay minerals in engineered bentonite barriers: nucleation and growth of secondary clay particles

    International Nuclear Information System (INIS)

    Fritz, B.; Clement, A.; Zwingmann, H.; Noguera, C.

    2010-01-01

    Document available in extended abstract form only. The long term stability of clay rich rocks used as barriers to the migration of radionuclides in the environment of nuclear wastes has been intensively studied, looking at the geochemical interactions between clay minerals and aqueous solutions. These studies combine experimental approaches for the short term and numerical modellings for the long term extrapolations, in the frame of the research supported by ANDRA in the French design for High Level Waste (HLW) repository. The main objective of the geochemical numerical tools devoted to clay-solutions interaction processes was to predict the feed-back effects of mineralogical and chemical transformations of clay mineral, in repository conditions as defined by Andra, on their physical and transport properties (porosity, molecular diffusion, permeability). The 1D transport-reaction coupled simulation was done using the code KIRMAT, at 100 deg. C for 100000 years. The fluid considered is that of the Callovo-Oxfordian geological formation (COX) and assumed to diffuse into the clay barrier from one side. On the other side, ferrous iron, is provided by the steel overpack corrosion. Under these conditions, montmorillonite of the clay barrier is only partially transformed into illite, chlorite, and saponite. The simulation shows that only outer parts of the clay barrier is significantly modified, mainly at the interface with the geological environment. These modifications correspond to a closure of the porosity, followed by a decrease of mass transport by molecular diffusion. Near the COX, the swelling pressure of the clays from the barrier is predicted to decrease, but in its major part, the engineered barrier seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure). In this modelling approach, the very important role of secondary clay minerals has to be taken into account with relevant kinetic rate laws; particularly

  7. Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

    International Nuclear Information System (INIS)

    Wu, Xiu-Wen; Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang

    2016-01-01

    Highlights: • Composite membranes are prepared with different montmorillonites and nafion solution. • Proton conductivities of the composite membranes are between 36.0 mS/cm and 38.5 mS/cm. • Ethanol permeability is between 0.69 × 10"−"6 cm"2/s and 2.67 × 10"−"6 cm"2/s. • Water uptake is approximately 24.30 mass%. - Abstract: The preparation of Nafion membranes modified with montmorillonites is less studied, and most relative works mainly applied in direct methanol fuel cells, less in direct ethanol fuel cells. Organic/inorganic composite membranes are prepared with different montmorillonites (Ca-montmorillonite, Na-montmorillonite, K-montmorillonite, Mg-montmorillonite, and H-montmorillonite) and Nafion solution via casting method at 293 K in air, and with balance of their proton conductivity and ethanol permeability. The ethanol permeability and proton conductivity of the membranes are comparatively studied. The montmorillonites can well decrease the ethanol permeability of the membranes via inserted them in the membranes, while less decrease the proton conductivities of the membranes depending on the inserted amount and type of montmorillonites. The proton conductivities of the membranes are between 36.0 mS/cm and 38.5 mS/cm. The ethanol permeability of the membranes is between 0.69 × 10"−"6 cm"2/s and 2.67 × 10"−"6 cm"2/s.

  8. Behavior of adsorbed Poly-A onto sodium montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Palomino-Aquino, Nayeli [Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México (Mexico); Negrón-Mendoza, Alicia, E-mail: negron@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México (Mexico)

    2015-07-23

    The adsorption of Poly-A (a polynucleotide consisting of adenine, ribose and a phosphate group), onto a clay mineral, was studied to investigate the extent of adsorption, the site of binding, and the capacity of the clay to protect Poly-A, while it is adsorbed onto the clay, from external sources of energy. The results showed that Poly-A presented a high percentage of adsorption at the edges of the clay and that the survival of the polynucleotide was superior to irradiating the polymer in the absence of the clay.

  9. Thixotropic Properties of Latvian Clays

    OpenAIRE

    Lakevičs, Vitālijs; Stepanova, Valentīna; Ruplis, Augusts

    2015-01-01

    This research studies Latvia originated Devon (Tūja, Skaņkalne), quaternary (Ceplīši), Jurassic, (Strēļi) and Triassic (Vadakste) deposit clays as well as Lithuania originated Triassic (Akmene) deposit clays. Thixotropic properties of clay were researched by measuring relative viscosity of clay in water suspensions. Relative viscosity is measured with a hopper method. It was detected that, when concentration of suspension is increased, clay suspension’s viscosity also increases. It happens un...

  10. Effect of telechelic ionic groups on the dispersion of organically modified clays in bisphenol A polycarbonate nanocomposites by in-situ polymerization using activated carbonates

    Directory of Open Access Journals (Sweden)

    M. Colonna

    2017-05-01

    Full Text Available Nanocomposites of bisphenol A polycarbonate with organically modified clays have been prepared for the first time by in-situ polymerization using bis(methyl salicyl carbonate as activated carbonate. The use of the activated carbonate permits to conduct the polymerization reaction at lower temperature and with shorter polymerization time with respect to those necessary for traditional melt methods that uses diphenyl carbonate, affording a nanocomposite with improved color. Moreover, an imidazolium salt with two long alkyl chains has been used to modify the montmorillonite, providing an organically modified clay with high thermal stability and wide d-spacing. The addition of ionic groups at the end of the polymer chain increases the interaction between the clay surface and the polymer producing a better dispersion of the clay. The presence of the clay increases the thermal stability of the polymer.

  11. Influence of the stirring time on the exfoliation of the Cloisite 30 B clay in PVC composite: structural characterization by XRD

    International Nuclear Information System (INIS)

    Cabral, Andreia M.V.; Rodrigues, Meiry G.F.

    2009-01-01

    This study aims to evaluate the influence of the stirring time on the exfoliation efficiency of the montmorillonite clay in PVC composites, prepared by the polymerization 'in situ' process. The work was performed in 2 steps. In first stage: tests of expansion with Cloisite 30B clay in MVC, which was used to assess the degree of expansion in MVC of each of them at different stirring times: 2, 4 and 6 h. After stirring, each system was kept in observation for 3 days to evaluate the changes in the decanted volume of the clay in the reactor. Second stage: the Influence of the stirring time for the clay exfoliation. Cloisite 30B clay was used to compare the influence of the stirring time for exfoliation and characterized by X-ray diffraction (XRD). (author)

  12. Properties of poly(lactic acid nanocomposites based on montmorillonite, sepiolite and zirconium phosphonate

    Directory of Open Access Journals (Sweden)

    K. Fukushima

    2012-11-01

    Full Text Available Poly(lactic acid (PLA based nanocomposites based on 5 wt.% of an organically modified montmorillonite (CLO, unmodified sepiolite (SEP and organically modified zirconium phosphonate (ZrP were obtained by melt blending. Wide angle X-ray scattering (WAXS and scanning electron microscopy (SEM analysis showed a different dispersion level depending on the type and functionalisation of nanoparticles. Differenctial scanning calorimetric (DSC analysis showed that PLA was able to crystallize on heating, and that the addition of ZrP could promote extent of PLA crystallization, whereas the presence of CLO and SEP did not significantly affect the crystallization on heating and melting behaviour of PLA matrix. Dynamic Mechanical Thermoanalysis (DMTA results showed that addition of all nanoparticles brought considerable improvements in E' of PLA, resulting in a remarkable increase of elastic properties for PLA nanocomposites. The melt viscosity and dynamic shear moduli (G',G" of PLA nanocomposites were also enhanced significantly by the presence of CLO and SEP, and attributed to the formation of a PLA/nanoparticle interconnected structure within the polymer matrix. The oxygen permeability of PLA did not significantly vary upon addition of SEP and ZrP nanoparticles. Only addition of CLO led to about 30% decrease compared to PLA permeability, due to the good clay dispersion and clay platelet-like morphology. The characteristic high transparency of PLA in the visible region was kept upon addition of the nanoparticles. Based on these achievements, a high potential of these PLA nanocomposites in sustainable packaging applications could be envisaged.

  13. Preparation of organo clays thermally stable to be employed as filler in PET nano composites

    International Nuclear Information System (INIS)

    Leite, I.F.; Soares, A.P.S.; Silva, S.M.L.; Malta, O.M.L.

    2009-01-01

    Thermal stability of organically modified clays is fundamental to melt processing polymer nanocomposites, especially, poly(terephthalate ethylene) (PET). However, the use of organic salts with high thermal stability is factor essential to obtaining of organoclays with great thermal properties. This work has as purpose to evaluate the influence of organic modifier based on alkyl ammonium, alkyl phosphonium and aryl phosphonium, in the clay organic modification visa to improve thermal properties to use as filler in nanocomposites preparation, where temperatures at about 260 deg C will be employed. The most common, and commercially available, surfactants used for cation exchange reactions with montmorillonites, rendering them organophilic, are quaternary ammonium salts, that when present as cations in montmorillonite, typically begin degradation at above 200 deg C. However, organoclays prepared with quaternary alkyl phosphonium salts may be potentially useful for the organoclays preparation stable thermally. In this study bentonite clay from Bentonit Uniao Nordeste/PB was purified and organically modified with the organic salts reported above. Organoclays were characterized by X-ray fluorescence, X-ray diffraction, infrared spectroscopy and analysis thermogravimetry. The results shown that the samples modified with the salts based on phosphonium presented higher thermal stability that the alkyl ammonium salt. (author)

  14. Sodium-calcium ion exchange on clay minerals at moderate to high ionic strengths

    International Nuclear Information System (INIS)

    Rogers, W.J.

    1979-12-01

    Sodium-calcium ion exchange on several clay minerals was studied at ionic strengths ranging from 0.01 to above 1.0. The minerals studied included attapulgite, illite, kaolin, and several montmorillonites. Distribution coefficients of calcium and sodium were obtained for the minerals over a wide range of solution conditions at pH five and equilibrium constants were calculated. The distribution coefficient of calcium, D/sub Ca/, was studied as a function of time, solution pH, loading, sodium concentration, and ionic strength fraction of sodium in constant ionic strength solutions. The distribution coefficient of sodium, D/sub Na/, was also studied as a function of time, loading, and sodium ionic strength fraction in constant total ionic strength solutions. Values of equilibrium constants calculated from distribution coefficients for solutions of constant ionic strength scattered bwteen 2 and 10 kg/kg for the montmorillonites and attapulgite while equilibrium constants for illite ranged from 5 to 10 kg/kg. No equilibrium constants for kaolin were calculated since distribution coefficients of sodium on this clay were too small to be measured. It was found that equilibrium constants at trace sodium loading were generally lower than those for higher sodium loadings by an order of magnitude or more due to the sensitivity of sodium distribution coefficients to the concentration of sodium in the clay at low loadings. Theoretical and experimental treatments of ion exclusion were included

  15. Thermal stability of segmented polyurethane elastomers reinforced by clay particles

    Directory of Open Access Journals (Sweden)

    Pavličević Jelena

    2009-01-01

    Full Text Available The aim of this work was to determine the influence of clay nanoparticles on thermal properties of segmented polyurethanes based on hexamethylene- diisocyanate, aliphatic polycarbonate diol and 1,4-butanediol as chain extender. The organically modified particles of montmorillonite and bentonite were used as reinforcing fillers. The structure of elastomeric materials was varied either by diol type or chain extender content. The ratio of OH groups from diol and chain extender (R was either 1 or 10. Thermal properties of prepared materials were determined using modulated differential scanning calorimetry (MDSC. Thermal stability of obtained elastomers has been studied by simultaneously thermogravimetry coupled with DSC. The glass transition temperature, Tg, of soft segments for all investigated samples was about -33°C. On the basis of DTG results, it was concluded that obtained materials were very stable up to 300°C.

  16. Preparation and characterization of bentonite clay for formation of nanocomposites

    International Nuclear Information System (INIS)

    Santos, J.J.M.; Silva, B.L.; Araujo, I.J.C.; Medeiros, A.M.; Melo, J.D.D.; Paskocimas, C.A.

    2011-01-01

    This study we used the linear medium density polyethylene (PELMD) as polymer matrix and introduced, as reinforcement to increase the mechanical and thermal properties, the green bentonite deposit of Boa Vista/PB, rich montmorillonite (MMT), previously characterized by XRD, that passed by three stages of purification. The first stage was to clean by washing and filtering for removal of coarse material (sand and organic matter), followed by an acid attack. In the second, we used the quaternary ammonium surfactant, in order to increase the distance between the layers of MMT, and the third was removed from the wastewater, using absolute ethanol, finishing the purification of process. Then, the clay was introduced into the polymer matrix by polymerization in solution by intercalation and characterized by XRD. The results showed a partial exfoliation, satisfying the increasing properties. (author)

  17. Barrier Properties of Polylactic Acid in Cellulose Based Packages Using Montmorillonite as Filler

    Directory of Open Access Journals (Sweden)

    Daniela Sánchez Aldana

    2014-09-01

    Full Text Available Polylactic acid (PLA and montmorillonite (CB as filler were studied as coatings for cellulose based packages. Amorphous (AM and semi crystalline (SC PLA were used at different concentrations according to a 2 × 6 × 3 full factorial experimental design. CB loading was three concentrations and coating was performed by casting. Contact angle (CA, water vapor (WVP and grease permeabilities were measured for each resultant package and were compared to commercial materials (Glassine Paper, Grease Proof Papers 1 and 2 produced commercially. Significant differences were found and the main factors were the type and concentration of PLA. The best values were: for grease penetration, +1800 s; WVP from 161.36 to 237.8 g·µm·kPa−1·m−2·d−1 and CA from 69° to 73° for PLA–AM 0.5% and CB variable. These parameters are comparable to commercial packages used in the food industry. DSC revealed three different thermal events for PLA–SC and just Tg for PLA–AM. Crystallinity was also verified, obtaining a ΔHcrys of 3.7 J·g−1 for PLA–SC and 14 J·g−1 for PLA–SC–BC, evidencing clay interaction as a crystal nucleating agent. Differences found were explained on terms of the properties measured, where structural and chemical arrays of the coatings play a fundamental role for the barrier properties.

  18. Processing and rheological characterization of poly(butylene adipate co-terephalate)/montmorillonite nanocomposites

    International Nuclear Information System (INIS)

    Beatrice, Cesar A.G.; Marini, Juliano; Bretas, Rosario E.S.; Branciforti, Marcia C.; Favaro, Marcia M.

    2009-01-01

    The rheological steady state and the linear viscoelastic properties of poly(butylene adipate co-terephthalate) (PBAT) / nanoclay nanocomposites were investigated. For this study, nanocomposites of PBAT and a chemically modified montmorillonite (MMT) were prepared by melt blending in a Haake Rheomix 600p rheometer at 140 and 160 deg C. The concentration of nanoclay was 5wt%. The samples obtained were characterized by x-ray diffraction (WAXS) and rheological measurements in an ARES (Rheometric Scientific) and AR-G2 (TA) rheometers, both with parallel plates geometry. It was confirmed by WAXS that the platelets of the nanoclay were intercalated in all samples, as the discernible sharp reflection of the (001) clay's diffraction was found in the x-ray diffractions patterns. The storage moduli (G') and the loss moduli (G ) of the nanocomposites increased with nanoclay content, at low frequencies. The presence of nanoclay caused these nanocomposites melts to have solid-like behaviors, which can be explained in terms of the development of a percolated network structure. (author)

  19. Molecular Dynamics Study of Crystalline Swelling of Montmorillonite as Affected by Interlayer Cation Hydration

    Science.gov (United States)

    Li, Hongliang; Song, Shaoxian; Dong, Xianshu; Min, Fanfei; Zhao, Yunliang; Peng, Chenliang; Nahmad, Yuri

    2018-04-01

    Swelling of montmorillonite (Mt) is an important factor for many industrial applications. In this study, crystalline swelling of alkali-metal- and alkaline-earth-metal-Mt has been studied through energy optimization and molecular dynamics simulations using the clay force field by Materials Studio 8.0. The delamination and exfoliation of Mt are primarily realized by crystalline swelling caused by the enhanced interlayer cation hydration. The initial position of the interlayer cations and water molecules is the dominated factor for the accuracy of the Mt simulations. Crystalline swelling can be carried out in alkali-metal-Mt and Mg-Mt but with difficulty in Ca-Mt, Sr-Mt and Ba-Mt. The crystalline swelling capacity values are in the order Na-Mt > K-Mt > Cs-Mt > Mg-Mt. This order of crystalline swelling of Mt in the same group can be attributed to the differences between the interlayer cation hydration strengths. In addition, the differences in the crystalline swelling between the alkali-metal-Mt and alkaline-earth-metal-Mt can be primarily attributed to the valence of the interlayer cations.

  20. Fabrication and Characterization of Cellulose Acetate/Montmorillonite Composite Nanofibers by Electrospinning

    Directory of Open Access Journals (Sweden)

    Se Wook Kim

    2015-01-01

    Full Text Available Nanofibers composed of cellulose acetate (CA and montmorillonite (MMT were prepared by electrospinning method. MMT was first dispersed in water and mixed with an acetic acid solution of CA. The viscosity and conductivity of the CA/MMT solutions with different MMT contents were measured to compare with those of the CA solution. The CA/MMT solutions were electrospun to fabricate the CA/MMT composite nanofibers. The morphology, thermal stability, and crystalline and mechanical properties of the composite nanofibers were characterized by scanning electron microscopy (SEM, transmission electron microscopy (TEM, energy dispersive X-ray spectroscopy (EDX, thermogravimetric analysis (TGA, X-ray diffraction (XRD, and tensile test. The average diameters of the CA/MMT composite nanofibers obtained by electrospinning 18 wt% CA/MMT solutions in a mixed acetic acid/water (75/25, w/w solvent ranged from 150~350 nm. The nanofiber diameter decreased with increasing MMT content. TEM indicated the coexistence of CA nanofibers. The CA/MMT composite nanofibers showed improved tensile strength compared to the CA nanofiber due to the physical protective barriers of the silicate clay layers. MMT could be incorporated into the CA nanofibers resulting in about 400% improvement in tensile strength for the CA sample containing 5 wt% MMT.

  1. Effect of Montmorillonite Nanogel Composite Fillers on the Protection Performance of Epoxy Coatings on Steel Pipelines.

    Science.gov (United States)

    Atta, Ayman M; El-Saeed, Ashraf M; Al-Lohedan, Hamad A; Wahby, Mohamed

    2017-06-02

    Montmorillonite (MMT) clay mineral is widely used as filler for several organic coatings. Its activity is increased by exfoliation via chemical modification to produce nanomaterials. In the present work, the modification of MMT to form nanogel composites is proposed to increase the dispersion of MMT into epoxy matrices used to fill cracks and holes produced by the curing exotherms of epoxy resins. The dispersion of MMT in epoxy improved both the mechanical and anti-corrosion performance of epoxy coatings in aggressive marine environments. In this respect, the MMT surfaces were chemically modified with different types of 2-acrylamido-2-methyl propane sulfonic acid (AMPS) nanogels using a surfactant-free dispersion polymerization technique. The effect of the chemical structure, nanogel content and the interaction with MMT surfaces on the surface morphology, surface charges and dispersion in the epoxy matrix were investigated for use as nano-filler for epoxy coatings. The modified MMT nanogel epoxy composites showed excellent resistance to mechanical damage and salt spray resistance up to 1000 h. The interaction of MMT nanogel composites with the epoxy matrix and good response of AMPS nanogel to sea water improve their ability to act as self-healing materials for epoxy coatings for steel.

  2. Physical and mechanical properties of hybrid montmorillonite/zinc oxide reinforced carboxymethyl cellulose nanocomposites.

    Science.gov (United States)

    Zahedi, Younes; Fathi-Achachlouei, Bahram; Yousefi, Ali Reza

    2018-03-01

    In this research, a novel carboxymethyl cellulose (CMC)-based nanocomposite films containing sodium montmorillonite (MMT) (5%wt) and zinc oxide (ZnO) (1, 2, 3 and 4%wt) nanoparticles (NPs) were fabricated via casting method. The results revealed that addition of NPs decreased water vapor permeability of the films by about 53%, while moisture content, density and glass transition temperature increased. The nanomaterials enhanced resistance of the nanocomposites against tensile stress at the expense of elongation at break. Nano-ZnO was very effective than nanoclay in UV-light blocking (99% vs. 60%) associated with sacrificing the films transparency. Formation of hydrogen bonds between the hydroxyl groups of CMC and MMT was evidenced by FTIR spectroscopy. According to the XRD analysis, clay nanolayers formed an exfoliated structure in the nanocomposites, whereas ZnO NPs raised crystallinity. SEM micrographs showed well-dispersed MMT and ZnO NPs through the films surface. Antibacterial test showed that vulnerability of Gram-positive S. aureus toward ZnO NPs was more than that of Gram-negative E. Coli. In conclusion, simultaneous incorporation of MMT and ZnO NPs improved the functional characteristics of CMC film and extended the potential for food packaging applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Mechanical, Thermal, and Microstructural Analysis of Polyvinyl Alcohol/Montmorillonite Nanocomposites

    Directory of Open Access Journals (Sweden)

    P. G. Allison

    2015-01-01

    Full Text Available Structural biomaterials such as nacre, bone, and fish scales possess unique structures that have hierarchical spatial configurations, which provide excellent mechanical properties when compared to their individual constituents. These observations have been the motivation for designing and characterizing bioinspired materials with high strength, high stiffness, and corrosion-resistant properties while at the same time being environmentally friendly. It has been demonstrated that polymer-clay nanocomposites can simulate the behavior of nacreous biomaterials such as abalone shell. Mechanical, thermal, and microstructural analyses characterized solution-cast polyvinyl alcohol (PVA/montmorillonite (MMT nanocomposite properties over compositions ranging from the neat polymer to 25% volume fraction of MMT nanoclay. Uniaxial tensile experiments were performed at displacement rates of 1 mm/min and 50 mm/min. Strength values are similar to those shown by nacre and represent a homogeneous dispersion of the MMT in the polymer matrix. Strength-to-weight ratios are similar to many structural metals.

  4. Correlation between thermal behavior of clays and their chemical and mineralogical composition: a review

    Science.gov (United States)

    Dwi Yanti, Evi; Pratiwi, I.

    2018-02-01

    Clay's abundance has been widely used as industrial raw materials, especially ceramic and tile industries. Utilization of these minerals needs a thermal process for producing ceramic products. Two studies conducted by Septawander et al. and Chin C et al., showed the relationship between thermal behavior of clays and their chemical and mineralogical composition. Clays are characterized by XRD analysis and thermal analysis, ranging from 1100°C to 1200°C room temperature. Specimen of raw materials of clay which is used for the thermal treatment is taken from different geological conditions and formation. In raw material, Quartz is almost present in all samples. Halloysite, montmorillonite, and feldspar are present in Tanjung Morawa raw clay. KC and MC similar kaolinite and illite are present in the samples. The research illustrates the interrelationships of clay minerals and chemical composition with their heat behavior. As the temperature of combustion increases, the sample reduces a significant weight. The minerals which have undergone a transformation phase became mullite, cristobalite or illite and quartz. Under SEM analysis, the microstructures of the samples showed irregularity in shape; changes occurred due the increase of heat.

  5. Kinetics and Products of Chromium(VI) Reduction by Iron(II/III)-Bearing Clay Minerals.

    Science.gov (United States)

    Joe-Wong, Claresta; Brown, Gordon E; Maher, Kate

    2017-09-05

    Hexavalent chromium is a water-soluble pollutant, the mobility of which can be controlled by reduction of Cr(VI) to less soluble, environmentally benign Cr(III). Iron(II/III)-bearing clay minerals are widespread potential reductants of Cr(VI), but the kinetics and pathways of Cr(VI) reduction by such clay minerals are poorly understood. We reacted aqueous Cr(VI) with two abiotically reduced clay minerals: an Fe-poor montmorillonite and an Fe-rich nontronite. The effects of ionic strength, pH, total Fe content, and the fraction of reduced structural Fe(II) [Fe(II)/Fe(total)] were examined. The last variable had the largest effect on Cr(VI) reduction kinetics: for both clay minerals, the rate constant of Cr(VI) reduction varies by more than 3 orders of magnitude with Fe(II)/Fe(total) and is described by a linear free energy relationship. Under all conditions examined, Cr and Fe K-edge X-ray absorption near-edge structure spectra show that the main Cr-bearing product is a Cr(III)-hydroxide and that Fe remains in the clay structure after reacting with Cr(VI). This study helps to quantify our understanding of the kinetics of Cr(VI) reduction by Fe(II/III)-bearing clay minerals and may improve predictions of Cr(VI) behavior in subsurface environments.

  6. Studies on silica sol-clay particle interactions by small-angle neutron scattering

    International Nuclear Information System (INIS)

    Moini, A.; Pinnavaia, T.J.; Michigan State Univ., East Lansing; Thiyagarajan, P.; White, J.W.

    1988-01-01

    SANS data were collected on a series of hydrolyzed silica and silica-clay complexes prepared from a 40 A silica sol and aqueous suspensions of Na + montmorillonite. The hydrolyzed silica product showed a peak centered at Q=0.0856 A -1 corresponding to a distance of 73 A between the sol particles. For such an evaporated gel in which the particles are in close contact, this distance is expected to be very close to the particle diameter indicating partial aggregation of the original spheres. A similar feature was observed in the SANS data for silica-clay products indicating the presence of some unintercalated silica. The intensity of this scattering was found to be dependent on the silica:clay ratio and the reaction time. The SANS data in the region from Q=0.006 to 0.025 A -1 were characteristic of clay scattering and exhibited a power-law behavior. The change in the slope of this curve upon reaction of the clay with the silica sol was interpreted in terms of a separation of clay platelets caused by a binding interaction with the sol particles. (orig.)

  7. Evaluation of mesopores and characterization of clays of the State of Puebla, Mexico

    International Nuclear Information System (INIS)

    Hernandez, M.A.; Velasco, J.A.; Rojas, F.; Lara, V.H.; Salgado, M.A.; Tamariz, V.

    2003-01-01

    The crystalline properties of natural clays are related to the different crystallographic phases that are present in the structure of these substrates. Clays from the zone of Tehuacan, in the state of Puebla, Mexico, have been studied by means of X-Ray Diffraction (XRD), Atomic Absorption (AA), and N 2 Adsorption at 76 K. XRD analysis indicates the presence in the clay adsorbents of montmorillonite, quartz and, in some cases, of calcium carbonate. The textural properties of these porous materials of natural origin have been evaluated through the BET equation, the Langmuir equation, the single point BET method and the Gurvitsch Rule. The meso porosity that is present in each substrate has been measured via the methods of Kelvin, Barret, Jovner, and Halenda (BJH), and Kruk, Jaroniec, and Sayari as well as by the so-called differential curves of t-plots. The N 2 adsorption isotherms at 76 K that were measured on our clay adsorbents indicate that the adsorption process is carried out through a multilayer formation mechanism. The sorption hysteresis loops confirm characteristic aspects of this type of clay materials. Plots of the adsorbed volume versus the statistical thickness (t-plots) of N 2 layers adsorbed on the clay surface were also evaluated. The latter curves comprise three zones of behavior; each zone representing a different filling mechanism of the pore space. (Author)

  8. Heteroagglomeration of zinc oxide nanoparticles with clay mineral modulates the bioavailability and toxicity of nanoparticle in Tetrahymena pyriformis.

    Science.gov (United States)

    Gupta, Govind Sharan; Senapati, Violet Aileen; Dhawan, Alok; Shanker, Rishi

    2017-06-01

    The extensive use of zinc oxide nanoparticles (ZnO NPs) in cosmetics, sunscreens and healthcare products increases their release in the aquatic environment. The present study explored the possible interaction of ZnO NPs with montmorillonite clay minerals in aqueous conditions. An addition of ZnO NPs on clay suspension significantly (pclay particles from 1652±90nm to 2158±13nm due to heteroagglomeration. The electrokinetic measurements showed a significant (pclay association (-1.37±0.03μmcm/Vs) that results to the electrostatic interaction between ZnO NPs and clay particles. The attenuated total reflectance Fourier transform infrared spectroscopy analysis of ZnO NPs-clay association demonstrated the binding of ZnO NPs with the Si-O-Al region on the edges of clay particles. The increase in size of ZnO NPs-clay heteroagglomerates further leads to their sedimentation at 24h. Although, the stability of ZnO NPs in the clay suspension was decreased due to heteroagglomeration, but the bioavailability and toxicity of ZnO NPs-clay heteroagglomerates in Tetrahymena pyriformis was enhanced. These observations provide an evidence on possible mechanisms available in natural environment that can facilitate nanoparticles entry into the organisms present in lower trophic levels of the food web. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Modelling aqueous solubility of sodium chloride in clays at thermodynamic conditions of hydraulic fracturing by molecular simulations.

    Science.gov (United States)

    Moučka, Filip; Svoboda, Martin; Lísal, Martin

    2017-06-28

    To address the high salinity of flow-back water during hydraulic fracturing, we have studied the equilibrium partitioning of NaCl and water between the bulk phase and clay pores. In shale rocks, such a partitioning can occur between fractures with a bulk-like phase and clay pores. We use an advanced Grand Canonical Monte Carlo (GCMC) technique based on fractional exchanges of dissolved ions and water molecules. We consider a typical shale gas reservoir condition of a temperature of 365 K and pressure of 275 bar, and we represent clay pores by pyrophyllite and Na-montmorillonite slits of a width ranging from about 7 to 28 Å, covering clay pores from dry clay to clay pores with a bulk-like layer in the middle of the pore. We employ the Joung-Cheatham model for ions, SPC/E model for water and CLAYFF for the clay pores. We first determine the chemical potentials for NaCl and water in the bulk phase using Osmotic Ensemble Monte Carlo simulations. The chemical potentials are then used in GCMC to simulate the adsorption of ions and water molecules in the clay pores, and in turn to predict the salt solubility in confined solutions. Besides the thermodynamic properties, we evaluate the structure and in-plane diffusion of the adsorbed fluids, and ion conductivities.

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

    Directory of Open Access Journals (Sweden)

    V. Pinti

    2012-07-01

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

  11. Atomistic simulations of cation hydration in sodium and calcium montmorillonite nanopores

    Science.gov (United States)

    Yang, Guomin; Neretnieks, Ivars; Holmboe, Michael

    2017-08-01

    During the last four decades, numerous studies have been directed to the swelling smectite-rich clays in the context of high-level radioactive waste applications and waste-liners for contaminated sites. The swelling properties of clay mineral particles arise due to hydration of the interlayer cations and the diffuse double layers formed near the negatively charged montmorillonite (MMT) surfaces. To accurately study the cation hydration in the interlayer nanopores of MMT, solvent-solute and solvent-clay surface interactions (i.e., the solvation effects and the shape effects) on the atomic level should be taken into account, in contrast to many recent electric double layer based methodologies using continuum models. Therefore, in this research we employed fully atomistic simulations using classical molecular dynamics (MD) simulations, the software package GROMACS along with the CLAYFF forcefield and the SPC/E water model. We present the ion distributions and the deformation of the hydrated coordination structures, i.e., the hydration shells of Na+ and Ca2+ in the interlayer, respectively, for MMT in the first-layer, the second-layer, the third-layer, the fourth-layer, and the fifth-layer (1W, 2W, 3W, 4W, and 5W) hydrate states. Our MD simulations show that Na+ in Na-MMT nanopores have an affinity to the ditrigonal cavities of the clay layers and form transient inner-sphere complexes at about 3.8 Å from clay midplane at water contents less than the 5W hydration state. However, these phenomena are not observed in Ca-MMT regardless of swelling states. For Na-MMT, each Na+ is coordinated to four water molecules and one oxygen atom of the clay basal-plane in the first hydration shell at the 1W hydration state, and with five to six water molecules in the first hydration shell within a radius of 3.1 Å at all higher water contents. In Ca-MMT, however each Ca2+ is coordinated to approximately seven water molecules in the first hydration shell at the 1W hydration state and

  12. THERMODINAMIC PARAMETERS ON THE SORPTION OF PHOSPHATE IONS BY MONTMORILLONITE

    Directory of Open Access Journals (Sweden)

    Ikhsan Jaslin

    2016-04-01

    Full Text Available The sorption of phosphate by montmorillonite at 10, 30, and 50 oC were investigated aiming to mainly determine thermodynamic parameters for the formation of surface complexes in the adsorption of phosphate ions by montmorillonite. Data were collected by adsorption edge experiments investigating the effect of pH, adsorption isotherms enabling the effect of sorbate concentration, and acid-base titration calculating protons released or taken up by adsorption process. Data analysis was carried out using surface complexation model to fit the data collected in this study using the parameters obtained from previous study, as well as to calculate the values of ΔH and ΔS. Previous study reported that phosphate ions formed two outer-sphere surface complexes with active sites of montmorillonite through hydrogen bonding. In the first complex,  [(XH0– H2L─]─, the phosphate was held to permanent-charge X─ sites on the tetrahedral siloxane faces, and the second complex, [[(SO─(SOH]– – [H2L]─] 2─ was formed through the interaction between the phosphate and variable charge surface hydroxyl groups at the edges of montmorillonite crystals and on the octahedral alumina faces. The values of ΔH for the first and second reactions are 39.756 and 3.765x10-7 kJ mol‒1 respectively. Since both reactions have positive enthalpy values, it can be concluded that the reactions are endothermic. Large energy for the first reaction is needed by X─  sites (permanent negatively charge sites of montmorillonite to be partially desolvated, on which K+ or other surface cations are replaced by H+ ions in the surface protonated process, and are then ready to interact phosphate ions in the solution. Small values of ΔH for the second reactions indicates that hydrogen bonds formed by phosphate and SOH sites in the second reaction are easily broken out, and the phosphate can easily desorbed from the surface. The values of ΔS for the first and second reactions are

  13. Ziegler-Natta Catalyst Based on MgCl₂/Clay/ID/TiCl₄ for the Synthesis of Spherical Particles of Polypropylene Nanocomposites.

    Science.gov (United States)

    Cardoso, Renata da Silva; Oliveira, Jaqueline da Silva; Ramis, Luciana Bortolin; Marques, Maria de Fátima V

    2018-07-01

    In the present work, we have designed MgCl2/clay/internal donor (ID)/TiCl4 based bisupported Ziegler-Natta catalysts containing varying amounts of organoclay (montmorillonite) in order to synthesize spherical particles of polypropylene/clay nanocomposites (PCN). The organoclay was introduced into the catalyst support formulation and PCN was obtained using the in situ polymerization technique. Decreasing the reaction time, it was possible to obtain nanocomposites with high concentrations of clay (masterbatches). Micrographs of SEM confirmed the spherical morphology of the catalysts. In addition, XRD patterns show that the active sites for polymerization were inserted in the clay galleries. The catalytic performance was evaluated in slurry propylene polymerization using triethylaluminium as cocatalyst and silane as external electron donor at 70 °C, 4 bar, and different reaction times. The PCNs obtained containing different clay amounts were characterized by X-ray diffraction, thermal analyses, transmission electronic microscopy, and extractables in heptane. The results revealed that the synthesized PP/clay particles were also spherical showing that the morphological control is possible even using catalysts containing high amounts of clay. The PCN presented high degradation temperature (459 °C). The XRD peak related to the clay interlamellar distance has shifted to lower angles, and TEM images confirmed the formation of exfoliated/intercalated clay on the PP matrix and absence of microparticles of clay.

  14. The elastoplastic response of and moisture diffusion through a vinyl ester resin-clay nanocomposite

    DEFF Research Database (Denmark)

    Drozdov, Aleksey D.; Christiansen, Jesper de Claville; Gupta, R.K.

    2002-01-01

    Experimental data are reported on the elastoplastic response of and moisture diffusion through a vinyl ester resin–montmorillonite clay nanocomposite with various amounts of filler. Two simple models are developed for the elastoplastic behavior of a nanocomposite and for the anomalous diffusion...... of penetrant molecules. Adjustable parameters in the constitutive equations are found by fitting the observations. It is revealed that some critical concentration of filler exists (about 1 wt.-%): in the sub-critical region of concentrations, molecular mobility of the host polymer strongly decreases...

  15. A desk study of surface diffusion and mass transport in clay

    International Nuclear Information System (INIS)

    Cook, A.J.

    1989-01-01

    Research into the properties of clays as barrier materials for nuclear waste disposal has led to the realization that they have important transport properties which are relatively insignificant in most other geological materials. Sorption has always been regarded as a purely retarding mechanism, but laboratory experiments over the past decade have indicated that surface diffusion of sorbed cations is a potentially significant transport mechanism in both compacted montmorillonite, and biotite gneiss. The present desk study about these issues was part of the CEC coordinated project Mirage-Second phase, research area Natural analogues

  16. Holocene debris flows on the Colorado Plateau: The influence of clay mineralogy and chemistry

    Science.gov (United States)

    Webb, R.H.; Griffiths, P.G.; Rudd, L.P.

    2008-01-01

    Holocene debris flows do not occur uniformly on the Colorado Plateau province of North America. Debris flows occur in specific areas of the plateau, resulting in general from the combination of steep topography, intense convective precipitation, abundant poorly sorted material not stabilized by vegetation, and the exposure of certain fine-grained bedrock units in cliffs or in colluvium beneath those cliffs. In Grand and Cataract Canyons, fine-grained bedrock that produces debris flows contains primarily single-layer clays - notably illite and kaolinite - and has low multilayer clay content. This clay-mineral suite also occurs in the colluvium that produces debris flows as well as in debris-flow deposits, although unconsolidated deposits have less illite than the source bedrock. We investigate the relation between the clay mineralogy and major-cation chemistry of fine-grained bedrock units and the occurrence of debris flows on the entire Colorado Plateau. We determined that 85 mapped fine-grained bedrock units potentially could produce debris flows, and we analyzed clay mineralogy and major-cation concentration of 52 of the most widely distributed units, particularly those exposed in steep topography. Fine-grained bedrock units that produce debris flows contained an average of 71% kaolinite and illite and 5% montmorillonite and have a higher concentration of potassium and magnesium than nonproducing units, which have an average of 51% montmorillonite and a higher concentration of sodium. We used multivariate statistics to discriminate fine-grained bedrock units with the potential to produce debris flows, and we used digital-elevation models and mapped distribution of debris-flow producing units to derive a map that predicts potential occurrence of Holocene debris flows on the Colorado Plateau. ?? 2008 Geological Society of America.

  17. Sorption behavior of thorium onto montmorillonite and illite

    International Nuclear Information System (INIS)

    Iida, Yoshihisa; Barr, Logan; Yamaguchi, Tetsuji; Hemmi, Ko

    2016-01-01

    Thorium (Th)-229 is one of the important radionuclides for the performance assessment calculations for high-level radioactive waste repositories. The sorption behavior of Th onto montmorillonite and illite were investigated by batch sorption experiments. Experiments were carried out under variable pH and carbonate concentrations. The sorbability of montmorillonite was higher than that of illite. Distribution coefficients, K d (m 3 kg -1 ), decreased with increased carbonate concentrations and showed the minimal value at around pH 10. The sorption behaviors of Th were analyzed by the non-electrostatic surface complex model with PHREEQC computer program. The model calculations were able to explain the experimental results reasonably well. The decreases of K d was likely due to the stabilization of aqueous species by hydroxo-carbonate complexations in the solutions. (author) [ja

  18. Silver nanoparticles in montmorillonite to application in polymeric materials

    International Nuclear Information System (INIS)

    Morita, R.Y.; Barbosa, R.V.; Kloss, J.R.; Schnitzler, M.; Garcia, J.

    2012-01-01

    This work presents the preparation of silver nanoparticles (AgNPs) through industrially viable methodologies and free of organic solvents, and their insertion in montmorillonite, to produce a nanomaterial with bactericidal properties. The modified montmorillonite was characterized through the techniques of Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and x-ray diffraction (XRD). The FTIR and Raman spectrum's showed specific bands of involving stretching silver. In the XRD analyses was observed the occurrence of the following crystallographic planes (111), (200) e (220) silver related. For application in low density polyethylene, the mechanical tests showed no loss in the mechanical properties, when the AgNPs is present, this fact is important and indicate that the nanomaterial can be inserted in this polymer matrix with considerable technology interest. (author)

  19. Flow-induced crystallization of a nano composite of poly(butylene adipate-co-terephthalate)/montmorillonite; Cinetica de cristalizacao induzida por fluxo de nanocomposito de poli(butileno adipato-co-tereftalato)/montmorilonita

    Energy Technology Data Exchange (ETDEWEB)

    Bonel, Alan B [Universidade Federal de Sao Carlos. UFSCar, Departamento de Engenharia de Materiais DEMa, SP (Brazil); Rego, Bruna T; Beatrice, Cesar A.G.; Marini, Juliano; Bretas, Rosario E.S., E-mail: bretas@ufscar.br [Universidade Federal de Sao Carlos. UFSCar, Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, SP (Brazil)

    2011-07-01

    Poly(butylene adipate-co-terephthalate) (PBAT) with 5wt% of an organically modified montmorillonite with polar surfactant was prepared by melt blending in a co-rotational twin-screw extruder at 160 degree C. 100rpm and 1 kg/h. Both pure polymer and nano composite were characterized by wide measurements. The study of the flow-induced crystallization was also done by rheological measurements, monitoring the viscosity as a function of time. The nano clay's lamellas were intercalated in the polymer m loss moduli of the nano composite, at low frequencies, showed that the particles of the nano clay were well dispersed and distributed thru the PBAT matrix. Finally, the presence of the nano clay's particles reduced the induction tim crystals growth, due to the strong interactions with the PBAT chains. (author)

  20. Study of selection and purification of Brazilian bentonite clay by elutriation: a XRF, SEM and Rietveld analysis

    Energy Technology Data Exchange (ETDEWEB)

    Alves, J.L.; Zanini, A.E.; Souza, M.E. de; Nascimento, M.L.F., E-mail: jeff_eq@yahoo.com.br, E-mail: mlfn@ufba.br [Universidade Federal da Bahia (UFBA/PROTEC/PEI), Salvador, BA (Brazil). Departamento de Engenharia Quimica

    2016-01-15

    Clays obtained from nature have a lot of impurities. Therefore, for best using of these materials, it is necessary its selection and purification. Thus, the aim of this work is to separate and to purify the smectite fractions using water as a solvent at a low flux mixed with a bentonite clay extracted from a mine in Vitoria da Conquista - Bahia / Brazil. For this a separation method of fractions of expandable clays based on the Stokes' Law was applied - this process is called elutriation, in order to ensure and to expand possible industrial applications of this material. The samples were characterized by analysis of X-ray diffraction, X-ray fluorescence and scanning electron microscopy. The Rietveld method enabled the quantification of main phase minerals: montmorillonite, kaolinite, nontronite and quartz, reaching 85% in mass of montmorillonite phase at the end of the process. Results showed that the method used was efficient to remove almost all quartz, carbonates and organic matter from the sample. It was also observed a monomodal grain size distribution of elutriated materials with thinner grains, around (18.1 ± 1.8) μm at the end of the process. It has been concluded that the method developed and applied showed promising characters to be applied to elutriate kilograms of clays and could be used in industrial scale. (author)

  1. Study of selection and purification of Brazilian bentonite clay by elutriation: a XRF, SEM and Rietveld analysis

    Directory of Open Access Journals (Sweden)

    J. L. Alves

    2016-03-01

    Full Text Available Abstract Clays obtained from nature have a lot of impurities. Therefore, for best using of these materials, it is necessary its selection and purification. Thus, the aim of this work is to separate and to purify the smectite fractions using water as a solvent at a low flux mixed with a bentonite clay extracted from a mine in Vitória da Conquista - Bahia / Brazil. For this a separation method of fractions of expandable clays based on the Stokes' Law was applied - this process is called elutriation, in order to ensure and to expand possible industrial applications of this material. The samples were characterized by analysis of X-ray diffraction, X-ray fluorescence and scanning electron microscopy. The Rietveld method enabled the quantification of main phase minerals: montmorillonite, kaolinite, nontronite and quartz, reaching 85% in mass of montmorillonite phase at the end of the process. Results showed that the method used was efficient to remove almost all quartz, carbonates and organic matter from the sample. It was also observed a monomodal grain size distribution of elutriated materials with thinner grains, around (18.1 ± 1.8 μm at the end of the process. It has been concluded that the method developed and applied showed promising characters to be applied to elutriate kilograms of clays and could be used in industrial scale.

  2. Characteristics of the streak clays of the hyacinth gold deposit by the techniques of DRX and AT

    International Nuclear Information System (INIS)

    Trueba Gaetano, R.; Cabrera Diaz, I.; Casanova Gomez, A.; Aguila Terry, A.; Martinez Montalvo, A.; Canel Carreras, L.; Rodriguez Garcia, J. C.; Alonso Perez, J. A.

    2016-01-01

    It is exposed the investigative work of the mineralogical characteristics of different types of clays present in the veins of the Oro Jacinto deposit through the use of XRD and TA analytical techniques, supported by a study of particle size in the range of 2 mm to 63 μm. Significant feature of these samples is that being crushed they generated high content of fine material below 0.074 mm. This size particles range is presented between 17.68% and 50.78% of samples volume, majority particles being smaller than 0.063 mm, this interstratificated fine material with different types of clay makes the fraction below 74 μm present characteristics of clayey material. The results of XRD analysis and comparative Thermo gravimetric that are achieved for samples of 'Jacinto' gold vein deposit indicate that the <