Alternative approaches to reliability modeling of a multiple engineered barrier system

International Nuclear Information System (INIS)

Ananda, M.M.A.; Singh, A.K.

1994-01-01

The lifetime of the engineered barrier system used for containment of high-level radioactive waste will significantly impact the total performance of a geological repository facility. Currently two types of designs are under consideration for an engineered barrier system, single engineered barrier system and multiple engineered barrier system. Multiple engineered barrier system consists of several metal barriers and the waste form (cladding). Some recent work show that a significant improvement of performance can be achieved by utilizing multiple engineered barrier systems. Considering sequential failures for each barrier, we model the reliability of the multiple engineered barrier system. Weibull and exponential lifetime distributions are used through out the analysis. Furthermore, the number of failed engineered barrier systems in a repository at a given time is modeled using a poisson approximation

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

Nanocomposites of rice and banana flours blend with montmorillonite: Partial characterization

Energy Technology Data Exchange (ETDEWEB)

Rodríguez-Marín, María L.; Bello-Pérez, Luis A. [Centro de Desarrollo de Productos Bióticos, Instituto Politécnico Nacional, Km 6 carr Yautepec-Jojutla, Calle Ceprobi No. 8, Colonia San Isidro, Apartado Postal 24, C.P 62731, Yautepec, Morelos (Mexico); Yee-Madeira, Hernani [Departamento de Física, Escuela Superior de Física y Matemáticas-IPN, Edificio 9, U.P., ‘Adolfo López Mateos’ Col. Lindavista, C.P. 07738, México, D. F. (Mexico); Zhong, Qixin [Department of Food science and Technology, the University of Tennessee, Knoxville (United States); González-Soto, Rosalía A., E-mail: rsoto@ipn.mx [Centro de Desarrollo de Productos Bióticos, Instituto Politécnico Nacional, Km 6 carr Yautepec-Jojutla, Calle Ceprobi No. 8, Colonia San Isidro, Apartado Postal 24, C.P 62731, Yautepec, Morelos (Mexico)

2013-10-15

Rice and banana flours are inexpensive starchy materials that can form films with more improved properties than those made with their starch because flour and starch present different hydrophobicity. Montmorillonite (MMT) can be used to further improve the properties of starch-based films, which has not received much research attention for starchy flours. The aim of this work was to evaluate the mechanical and barrier properties of nanocomposite films of banana and rice flours as matrix material with addition of MMT as a nanofiller. MMT was modified using citric acid to produce intercalated structures, as verified by the X-ray diffraction pattern. The intercalated MMT was blended with flour slurries, and films were prepared by casting. Nanocomposite films of banana and rice flours presented an increase in the tensile at break and elongation percentage, respectively, more than their respective control films without MMT. This study showed that banana and rice flours could be alternative raw materials to use in making nanocomposite films. - Highlights: • Flour films presented adequate mechanical and barrier properties. • Addition of montmorillonite modified the mechanical and barrier properties of flour films. • The mechanical properties of the films were influenced by the different components of the flours. • The fiber of the banana flour improved the mechanical properties of the films.

Nanocomposites of rice and banana flours blend with montmorillonite: Partial characterization

International Nuclear Information System (INIS)

Rodríguez-Marín, María L.; Bello-Pérez, Luis A.; Yee-Madeira, Hernani; Zhong, Qixin; González-Soto, Rosalía A.

2013-01-01

Rice and banana flours are inexpensive starchy materials that can form films with more improved properties than those made with their starch because flour and starch present different hydrophobicity. Montmorillonite (MMT) can be used to further improve the properties of starch-based films, which has not received much research attention for starchy flours. The aim of this work was to evaluate the mechanical and barrier properties of nanocomposite films of banana and rice flours as matrix material with addition of MMT as a nanofiller. MMT was modified using citric acid to produce intercalated structures, as verified by the X-ray diffraction pattern. The intercalated MMT was blended with flour slurries, and films were prepared by casting. Nanocomposite films of banana and rice flours presented an increase in the tensile at break and elongation percentage, respectively, more than their respective control films without MMT. This study showed that banana and rice flours could be alternative raw materials to use in making nanocomposite films. - Highlights: • Flour films presented adequate mechanical and barrier properties. • Addition of montmorillonite modified the mechanical and barrier properties of flour films. • The mechanical properties of the films were influenced by the different components of the flours. • The fiber of the banana flour improved the mechanical properties of the films

Thermal barrier coatings application in diesel engines

Science.gov (United States)

Fairbanks, J. W.

1995-01-01

Commercial use of thermal barrier coatings in diesel engines began in the mid 70's by Dr. Ingard Kvernes at the Central Institute for Industrial Research in Oslo, Norway. Dr. Kvernes attributed attack on diesel engine valves and piston crowns encountered in marine diesel engines in Norwegian ships as hot-corrosion attributed to a reduced quality of residual fuel. His solution was to coat these components to reduce metal temperature below the threshold of aggressive hot-corrosion and also provide protection. Roy Kamo introduced thermal barrier coatings in his 'Adiabatic Diesel Engine' in the late 70's. Kamo's concept was to eliminate the engine block water cooling system and reduce heat losses. Roy reported significant performance improvements in his thermally insulated engine at the SAE Congress in 1982. Kamo's work stimulates major programs with insulated engines, particularly in Europe. Most of the major diesel engine manufacturers conducted some level of test with insulated combustion chamber components. They initially ran into increased fuel consumption. The German engine consortium had Prof. Woschni of the Technical Institute in Munich. Woschni conducted testing with pistons with air gaps to provide the insulation effects. Woschni indicated the hot walls of the insulated engine created a major increase in heat transfer he refers to as 'convection vive.' Woschni's work was a major factor in the abrupt curtailment of insulated diesel engine work in continental Europe. Ricardo in the UK suggested that combustion should be reoptimized for the hot-wall effects of the insulated combustion chamber and showed under a narrow range of conditions fuel economy could be improved. The Department of Energy has supported thermal barrier coating development for diesel engine applications. In the Clean Diesel - 50 Percent Efficient (CD-50) engine for the year 2000, thermal barrier coatings will be used on piston crowns and possibly other components. The primary purpose of the

Barriers to student success in engineering education

Science.gov (United States)

Boles, Wageeh; Whelan, Karen

2017-07-01

In the UK, the USA and Australia, there have been calls for an increase in the number of engineering graduates to meet the needs of current global challenges. Universities around the world have been grappling with how to both attract more engineering students and to then retain them. Attrition from engineering programmes is disturbingly high. This paper reports on an element of research undertaken through an Australian Learning and Teaching Council-funded Fellowship that investigated the factors leading to student attrition in engineering programmes, by identifying barriers to student success. Here, we contrast a review of the literature related to student barriers and success with student perceptions, gathered through a series of focus groups and interviews at three Australian universities. We also present recommendations for action to try to remove barriers to student success.

Engineered barriers: current status

International Nuclear Information System (INIS)

Atkinson, A.; Marsh, G.P.

1988-01-01

This report summarises the current state of research relevant to assessing the performance of engineered barriers made of steel and concrete in radioactive waste repositories. The objective of these barriers is to contain the radionuclides within them by providing both physical and chemical impediment to their release. The physical barriers are of most value for highly soluble isotopes with relatively short half-lives (eg 137 Cs), since they can provide containment until a large fraction of the activity has decayed. In addition they can facilitate retrievability for some period after disposal. The chemical barriers operate by beneficial conditioning of the near field groundwater and providing sites for sorption of radionuclides. Both of these reduce the aqueous concentration of radionuclides in the near field. (author)

Performance of engineered barriers

International Nuclear Information System (INIS)

Rajaram, V.; Dean, P.V.; McLellan, S.A.

1997-01-01

Engineered barriers, both vertical and horizontal, have been used to isolate hazardous wastes from contact, precipitation, surface water and groundwater. The primary objective of this study was to determine the performance of subsurface barriers installed throughout the U.S. over the past 20 years to contain hazardous wastes. Evaluation of Resource Conservation and Recovery Act (RCRA) Subtitle C or equivalent caps was a secondary objective. A nationwide search was launched to select hazardous waste sites at which vertical barrier walls and/or caps had been used as the containment method. None of the sites selected had an engineered floor. From an initial list of 130 sites, 34 sites were selected on the basis of availability of monitoring data for detailed analysis of actual field performance. This paper will briefly discuss preliminary findings regarding the design, construction quality assurance/construction quality control (CQA/CQC), and monitoring at the 34 sites. In addition, the short-term performance of these sites (less than 5 years) is presented since very little long-term performance data was available

Engineering kinetic barriers in copper metallization

International Nuclear Information System (INIS)

Huang Hanchen; Wei, H.L.; Woo, C.H.; Zhang, X.X.

2002-01-01

In metallization processes of integrated circuits, it is desirable to deposit the metal lines (aluminum or copper) fast and at low temperatures. However, the lines (films) usually consist of undesirable columns and voids, because of the absence of sufficient diffusion--a direct result of large kinetic barriers. Following the proposal and realization of the three-dimensional Ehrlich-Schwoebel (3D ES) barrier, we present here a method to engineer this kinetic barrier so as to improve quality of deposited copper films. We deposit copper films by magnetron sputtering, characterize the film structure and texture by using the scanning electron microscope and the x-ray diffraction, respectively. Taking indium as surfactant during copper deposition, we have achieved much better density and bottom coverage of copper filled trenches. The characterizations show that the improvement is the result of the 3D ES barrier reduction caused by indium addition. Engineering the 3D ES barrier therefore leads to improved film quality

Engineered Barrier Test Facility status report, 1984

International Nuclear Information System (INIS)

Phillips, S.J.; Adams, M.R.; Gilbert, T.W.; Meinhardt, C.C.; Mitchell, R.M.; Waugh, W.J.

1985-02-01

This report provides a general summary of activities completed to date at the Hanford Engineered Barrier Test Facility. This facility is used to test and compare construction practices and performance of alternative designs of engineered barrier cover systems. These cover systems are being evaluated for potential use for isolation and confinement of buried waste disposal structures

Systems study on engineered barriers: barrier performance analysis

International Nuclear Information System (INIS)

Stula, R.T.; Albert, T.E.; Kirstein, B.E.; Lester, D.H.

1980-09-01

A performance assessment model for multiple barrier packages containing unreprocessed spent fuel has been modified and applied to several package designs. The objective of the study was to develop information to be used in programmatic decision making concerning engineered barrier package design and development. The assessment model, BARIER, was developed in previous tasks of the System Study on Engineered Barriers (SSEB). The new version discussed in this report contains a refined and expanded corrosion rate data base which includes pitting, crack growth, and graphitization as well as bulk corrosion. Corrosion rates for oxic and anoxic conditions at each of the two temperature ranges are supplied. Other improvements include a rigorous treatment of radionuclide release after package failure which includes resistance of damaged barriers and backfill, refined temperature calculations that account for convection and radiation, a subroutine to calculate nuclear gamma radiation field at each barrier surface, refined stress calculations with reduced conservatism and various coding improvements to improve running time and core usage. This report also contains discussion of alternative scenarios to the assumed flooded repository as well as the impact of water exclusion backfills. The model was used to assess post repository closure performance for several designs which were all variation of basic designs from the Spent Unreprocessed Fuel (SURF) program. Many designs were found to delay the onset of leaching by at least a few hundreds of years in all geologic media. Long delay times for radionuclide release were found for packages with a few inches of sorption backfill. Release of uranium, plutonium, and americium was assessed

Systems study on engineered barriers: barrier performance analysis

Energy Technology Data Exchange (ETDEWEB)

Stula, R.T.; Albert, T.E.; Kirstein, B.E.; Lester, D.H.

1980-09-01

A performance assessment model for multiple barrier packages containing unreprocessed spent fuel has been modified and applied to several package designs. The objective of the study was to develop information to be used in programmatic decision making concerning engineered barrier package design and development. The assessment model, BARIER, was developed in previous tasks of the System Study on Engineered Barriers (SSEB). The new version discussed in this report contains a refined and expanded corrosion rate data base which includes pitting, crack growth, and graphitization as well as bulk corrosion. Corrosion rates for oxic and anoxic conditions at each of the two temperature ranges are supplied. Other improvements include a rigorous treatment of radionuclide release after package failure which includes resistance of damaged barriers and backfill, refined temperature calculations that account for convection and radiation, a subroutine to calculate nuclear gamma radiation field at each barrier surface, refined stress calculations with reduced conservatism and various coding improvements to improve running time and core usage. This report also contains discussion of alternative scenarios to the assumed flooded repository as well as the impact of water exclusion backfills. The model was used to assess post repository closure performance for several designs which were all variation of basic designs from the Spent Unreprocessed Fuel (SURF) program. Many designs were found to delay the onset of leaching by at least a few hundreds of years in all geologic media. Long delay times for radionuclide release were found for packages with a few inches of sorption backfill. Release of uranium, plutonium, and americium was assessed.

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.

Engineered barrier development for a nuclear waste repository in basalt

International Nuclear Information System (INIS)

Smith, M.J.

1980-05-01

The BWIP Engineered Barrier Program has been developed to provide an integrated approach to the development of site-specific Engineered Barrier assemblages for a repository located in basalt. The goal of this program is to specify engineered and natural barriers which will ensure that nuclear and non-radioactive hazardous materials emplaced in a repository in basalt do not exceed acceptable rates of release to the biosphere. A wide range of analytical and experimental activities related to the basalt repository environment, waste package environment, waste/barrier/rock interactions, and barrier performance assessment provide the basis for selection of systems capable of meeting licensing requirements. Work has concentrated on specifying and testing natural and man-made materials which can be used to plug boreholes in basalt and which can be used as multiple barriers to surround nuclear waste forms and containers. The Engineered Barriers Program is divided into two major activities: multiple barrier studies and borehole plugging. 8 figures, 4 tables

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.

Study on vibration behaviors of engineered barrier system

International Nuclear Information System (INIS)

Mikoshiba, Tadashi; Ogawa, Nobuyuki; Minowa, Chikahiro

1998-01-01

High-level radioactive wastes have been buried underground by packing into a strong sealed container made from carbon steel (over-pack) with buffer material (bentonite). The engineered barrier system constructed with an overpack and buffer materials must be resistant to earthquakes as well as invasion of groundwater for a long period. Therefore, seismic evaluation of barrier system for earthquakes is indispensable especially in Japan to keep its structural safety. Here, the effects of earthquake vibration on the engineered barrier systems were investigated experimentally. Random-wave vibration and practical seismic wave one were loaded for the systems and fundamental data were obtained. For the former vibration the response characteristics of both engineered barrier models constructed with overpack and bentonite were non-linear. For the latter one, the stress in bentonite was increased in proportion to the vibration level. (M.N.)

Barrier Engineered Quantum Dot Infrared Photodetectors

Science.gov (United States)

2015-06-01

251108. 6. Barve, Ajit V., Saumya Sengupta, Jun Oh Kim, John Montoya , Brianna Klein, Mohammad Ali Shirazi, Marziyeh Zamiri et al., "Barrier selection... H . Kim, Z-B. Tian, and Sanjay Krishna. "Barrier Engineered Infrared Photodetectors Based on Type-II InAs/GaSb Strained Layer Superlattices." (2013

Near-Surface Engineered Environmental Barrier Integrity

International Nuclear Information System (INIS)

Piet, S.J.; Breckenridge, R.P.

2002-01-01

The INEEL Environmental Systems Research and Analysis (ESRA) program has launched a new R and D project on Near-Surface Engineered Environmental Barrier Integrity to increase knowledge and capabilities for using engineering and ecological components to improve the integrity of near-surface barriers used to confine contaminants from the public and the environment. The knowledge gained and the capabilities built will help verify the adequacy of past remedial decisions and enable improved solutions for future cleanup decisions. The research is planned to (a) improve the knowledge of degradation mechanisms (weathering, biological, geological, chemical, radiological, and catastrophic) in times shorter than service life, (b) improve modeling of barrier degradation dynamics, (c) develop sensor systems to identify degradation prior to failure, and (d) provide a better basis for developing and testing of new barrier systems to increase reliability and reduce the risk of failure. Our project combine s selected exploratory studies (benchtop and field scale), coupled effects accelerated aging testing and the meso-scale, testing of new monitoring concepts, and modeling of dynamic systems. The performance of evapo-transpiration, capillary, and grout-based barriers will be examined

ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

International Nuclear Information System (INIS)

Jarek, R.

2004-01-01

The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports

ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

International Nuclear Information System (INIS)

G.H. Nieder-Westermann

2005-01-01

The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports

Engineered barriers: current status 1989

International Nuclear Information System (INIS)

Atkinson, A.; Marsh, G.B.

1989-06-01

This report summarises the current state of research relevant to assessing the performance of engineered barriers made of steel and concrete in radioactive waste repositories. The objective of these barriers is to contain substantially the radionuclides within them by providing both physical and chemical impediment to their release. The physical barriers are of most value for highly soluble isotopes with relatively short half-lives (eg 137 Cs), since they can provide a measure of containment until a large fraction of the activity has decayed. In addition they can facilitate retrievability for some period after disposal. The chemical barriers operate by beneficial conditioning of the near field groundwater and providing sites for sorption of radionuclides. Both of these reduce the aqueous concentration of radionuclides in the near field. (author)

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.

Engineered Barrier System: Physical and Chemical Environment

International Nuclear Information System (INIS)

Dixon, P.

2004-01-01

The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports

Engineered barrier systems (EBS): design requirements and constraints

International Nuclear Information System (INIS)

2004-01-01

A joint NEA-EC workshop entitled 'Engineered Barrier Systems: Design Requirements and Constraints' was organised in Turku, Finland on 26-29 August 2003 and hosted by Posiva Oy. The main objectives of the workshop were to promote interaction and collaboration among experts responsible for engineering design and safety assessment in order to develop a greater understanding of how to achieve the integration needed for the successful design of engineered barrier systems, and to clarify the role that an EBS can play in the overall safety case for a repository. These proceedings present the outcomes of this workshop. (author)

ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

Energy Technology Data Exchange (ETDEWEB)

R. Jarek

2004-11-23

The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports.

ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

Energy Technology Data Exchange (ETDEWEB)

G.H. Nieder-Westermann

2005-04-07

The purpose of this report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The abstraction model is used in the total system performance assessment for the license application (TSPA LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of these abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2004 [DIRS 171156], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports.

Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

Science.gov (United States)

Wu, Xiu-Wen; Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang

2016-12-01

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 cm2/s and 2.67 × 10-6 cm2/s.

Engineered Barrier System: Physical and Chemical Environment

Energy Technology Data Exchange (ETDEWEB)

P. Dixon

2004-04-26

The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports.

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

Engineered Barrier Testing at the INEEL Engineered Barriers Test Facility: FY-1997 and FY-1998

International Nuclear Information System (INIS)

Keck, K. N.; Porro, I.

1998-01-01

Engineered barriers of two designs are being tested at the Engineered Barriers Test Facility (EBTF) at the Idaho National Engineering and Environmental Laboratory. This report describes the test facility, barrier designs, and instruments used to monitor the test plots. Wetting tests conducted on the test plots in FY-97 are described and data collected from monitoring the test plots before, during and after the wetting tests are used to evaluate the performance of the covers during FY-97 and FY-98. Replicates of two engineered barrier designs were constructed in the EBTF cells. The first design comprises a thick, vegetated soil cover. The second design incorporates a capillary/biobarrier within the vegtated soil cover. The capillary barrier uses the textural break between an upper, fine textured soil and a lower, coarser-textured gravel layer to inhibit drainage under unsaturated conditions while increasing soil moisture storage in the root zone. Evaporation and transpiration by plants (although the test plots have not yet been vegetated) are used to recycle water stored in the soil back to the atmosphere. A geotextile fabric is used to maintain separation of the soil and gravel layers. A thick layer of cobbles beneath the gravel layer serves as a biobarrier to prevent intrusion of plant roots and burrowing animals into underlying waste (there is no waste in the test plots). Each test plot was instrumented with time domain reflectometry probes and neutron probe access tubes to measure moisture contents, tensiometers, heat dissipation sensors, and thermocouple psychrometers to measure matric potentials, thermocouples to measure soil temperature, and ion-exchange resin beads to monitor tracer movement. Each drainage sump is equipped with a tipping bucket instrument and pressure transducer to measure drainage. Precipitation is measured using a heated rain gauge located at the EBTF. Instrument calibration equation coefficients are presented, and data reduction

Performance of engineered barriers for low-level waste

International Nuclear Information System (INIS)

Taplin, D.; Claridge, F.B.

1987-09-01

Geotechnical Resources Ltd., in association with Komex Consultants Ltd., was retained to collect, synthesize and evaluate the available information on the long term performance of engineered barriers for low-level radioactive wastes disposed in Canada. Literature was researched from Canadian, United States and European sources. A variety of barrier materials were assessed in the study and included natural clays, concrete and cement, metals, bentonite-sand admixes, bitumen and bituminous admixes, soil cement and polymeric membranes. The generalized geological and geotechnical conditions encountered within the soil and rock host media currently under consideration for disposal sites in southern Ontario were also summarized. Both internal barriers, or buffers, to immobilize the waste material and reduce radionuclide mobility, as well as external barriers to limit the migration of contaminants were examined. Microbial activities within the waste forms were analyzed, including cellulose degradation, methanogenesis and bicarbonate and organic reactions. Microbial interactions with the various engineered barrier materials under consideration were also assessed. Finally, the anticipated long term performances of the respective barrier materials under consideration were evaluated, along with the general suitability of the geological host media being proposed for disposal sites

Effect of the addition order and amylose content on mechanical, barrier and structural properties of films made with starch and montmorillonite.

Science.gov (United States)

Romero-Bastida, C A; Bello-Pérez, L A; Velazquez, G; Alvarez-Ramirez, J

2015-01-01

This study considered the effect of amylose content (30% and 70%), montmorillonite (MMT) fraction (5 and 15%) and preparation method on mechanical and barrier properties of starch/clay nanocomposites prepared by casting. In Method 1, (30% w/w) glycerol was incorporated before starch gelatinization and MMT addition, while in Method 2 after gelatinization and MMT addition. Nanocomposites with higher amount of MMT showed the highest tensile strength and Young's modulus for both preparation methods. Method 1 favored nanocomposite properties of films with less amylose content, meanwhile Method 2 favored nanocomposites properties with higher amylose content. Water vapor permeability did not decrease significantly in starch films with different amylose content with the two different preparation methods. X-ray diffraction of the starch films indicated intercalated structures. Higher melting temperature (Tm) was found for nanocomposites with Method 2, indicating more ordered structures. Films with 70% amylose content have higher Tm than films with 30% amylose. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

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

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

Natural analog study of engineered protective barriers at the Hanford Site

International Nuclear Information System (INIS)

Bjornstad, B.N.; Teel, S.S.

1993-09-01

The purpose of this study is to evaluate surficial sedimentary deposits formed in the Pasco Basin over the geologic past as analogs for engineered protective barriers. Evidence for likely changes to be expected in an engineered barrier are preserved in geologically recent deposits. Although the design life of the engineered bonier is only 1,000 years, soils and sediments of this age are uncommon in the Pasco Basin. The evidence of and probability for the following natural processes that could adversely affect the long-term stability of an engineered protective barrier reviewed in this report are deflation by wind, soil compaction, soil eluviation/illuviation, bioturbation, and cryoturbation

Engineered Barrier System: Physical and Chemical Environment Model

International Nuclear Information System (INIS)

Jolley, D. M.; Jarek, R.; Mariner, P.

2004-01-01

The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports

Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Wu, Xiu-Wen, E-mail: wuxw2008@163.com [School of Science, China University of Geosciences, Beijing 100083 (China); National Laboratory of Mineral Materials, China University of Geosciences, Beijing 100083 (China); Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang [School of Science, China University of Geosciences, Beijing 100083 (China)

2016-12-01

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{sup −6} cm{sup 2}/s and 2.67 × 10{sup −6} cm{sup 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{sup −6} cm{sup 2}/s and 2.67 × 10{sup −6} cm{sup 2}/s.

Preliminary engineering specifications for a test demonstration multilayer protective barrier cover system

International Nuclear Information System (INIS)

Phillips, S.J.; Gilbert, T.W.; Adams, M.R.

1985-03-01

This report presents preliminary engineering specifications for a test protective barrier cover system and support radiohydrology facility to be constructed at the Hanford Protective Barrier Test Facility (PBTF). Construction of this test barrier and related radiohydrology facility is part of a continuing effort to provide construction experience and performance evaluation of alternative barrier designs used for long-term isolation of disposed radioactive waste materials. Design specifications given in this report are tentative, based on interim engineering and computer simulation design efforts. Final definitive design specifications and engineering prints will be produced in FY 1986. 6 refs., 10 figs., 1 tab

Evaluation of engineered barriers at the Idaho National Engineering and Environmental Laboratory

International Nuclear Information System (INIS)

Bhatt, R.N.; Porro, I.

1998-03-01

Subsurface Disposal (SDA) of the Radioactive Waste Management Complex serves as the low level waste burial ground at the Idaho National Engineering and Environmental Laboratory (INEEL). The low level wastes are buried in trenches, pits, and soil vaults in surficial sediments. A closure/post-closure plan must be written prior to closure of the SDA. The closure plan for the facility must include a design for an engineered barrier closure cover that will meet all applicable regulatory requirements. This paper describes the approach being followed at the INEEL to choose an appropriate cover design for the SDA closure. Regulatory requirements and performance objectives potentially applicable to closure of the SDA were identified. Technical issues related to SDA closure were identified from a literature search of previous arid site engineered barrier studies and from previous SDA closure cover evaluations. Five engineered barrier conceptual design alternatives were identified: (1) a bio/capillary barrier cover, (2) a thin soil cover, (3) a thick soil cover, (4) a Resource Conservation and Recovery Act cover, and (5) a concrete sealed surface cover. Two of these designs were chosen for in situ hydraulic testing, rather than all five, in order to maximize the amount of information generated relative to projected project costs. Testing of these two cover designs provides data to quantify hydrologic model input parameters and for verification of site specific hydrologic models for long term closure cover performance evaluation and detailed analysis of closure cover alternatives. The specific objectives of the field tests are to determine the water balance for the two covers over several years and to determine cover soil physical and hydraulic properties

Engineered Barrier System: Physical and Chemical Environment Model

Energy Technology Data Exchange (ETDEWEB)

D. M. Jolley; R. Jarek; P. Mariner

2004-02-09

The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports.

Influences of engineered barrier systems on low-level radioactive waste disposal

International Nuclear Information System (INIS)

Buckley, L.P.

1987-09-01

There are major differences between the current practices of shallow land burial and alternative concepts for the disposal of low-level radioactive wastes. Additional protection provided with engineered barrier systems can overcome major concerns the public has with shallow land burial: subsidence; percolating ground waters; radionuclide migration; and the vulnerability of shallow trenches to intrusion. The presence of a variety of engineered barriers to restrict water movement, retain radionuclides and to prevent plant animal or human intrusion leads to significant changes to input data for performance assessment models. Several programs which are underway to more accurately predict the long-term performance of engineered barriers for low-level waste will be described

Influences of engineered barrier systems on low-level radioactive waste disposal

Energy Technology Data Exchange (ETDEWEB)

Buckley, L. P.

1987-09-15

There are major differences between the current practices of shallow land burial and alternative concepts for the disposal of low-level radioactive wastes. Additional protection provided with engineered barrier systems can overcome major concerns the public has with shallow land burial: subsidence; percolating ground waters; radionuclide migration; and the vulnerability of shallow trenches to intrusion. The presence of a variety of engineered barriers to restrict water movement, retain radionuclides and to prevent plant animal or human intrusion leads to significant changes to input data for performance assessment models. Several programs which are underway to more accurately predict the long-term performance of engineered barriers for low-level waste will be described.

Prototype Engineered Barrier System Field Tests

International Nuclear Information System (INIS)

Ramirez, A.L.; Beatty, J.; Buscheck, T.A.

1989-01-01

This paper presents selected preliminary results obtained during the first 54 days of the Prototype Engineered Barrier System Field Tests (PEBSFT) that are being performed in G-Tunnel within the Nevada Test Site. The test described is a precursor to the Engineered Barrier Systems Field Tests (EBSFT). The EBSFT will consist of in situ tests of the geohydrologic and geochemical environment in the near field (within a few meters) of heaters emplaced in welded tuff to simulate the thermal effects of waste packages. The PEBSFTs are being conducted to evaluate the applicability of measurement techniques, numerical models, and procedures for future investigations that will be conducted in the Exploratory Shaft Facilities of the Yucca Mountain Project (YMP). The paper discusses the evolution of hydrothermal behavior during the prototype test, including rock temperatures, changes in rock moisture content, air permeability of fractures, gas pressures, and rock mass gas-phase humidity. 10 refs., 12 figs

Reducing barriers to energy efficiency in the German mechanical engineering sector. Executive summary

Energy Technology Data Exchange (ETDEWEB)

Schleich, J.; Boede, U.

2000-12-01

This report describes the empirical research into barriers to energy efficiency in the German mechanical engineering (ME) sector. It is one of nine such reports in the BARRIERS project. The report contains description and analysis of four case studies of energy management in German companies in the ME sector. The results are analysed using the theoretical framework developed for the BARRIERS project. The report also provides brief recommendations on how these barriers to the rational use of energy (RUE) may be overcome and how energy efficiency within the ME sector may be improved. The results of the study for the ME sector in Germany are summarised in this executive summary under the following headings: - Characterising the mechanical engineering sector; - Case studies of energy management in the German mechanical engineering sector; - Evidence of barriers in the German mechanical engineering sector; - The role of energy service companies in the mechanical engineering sector; - Policy implications. (orig.)

Reducing barriers to energy efficiency in the German mechanical engineering sector. Final report

Energy Technology Data Exchange (ETDEWEB)

Schleich, J.; Boede, U.

2000-12-01

This report describes the empirical research into barriers to energy efficiency in the German mechanical engineering (ME) sector. It is one of nine such reports in the BARRIERS project. The report contains description and analysis of four case studies of energy management in German companies in the ME sector. The results are analysed using the theoretical framework developed for the BARRIERS project. The report also provides brief recommendations on how these barriers to the rational use of energy (RUE) may be overcome and how energy efficiency within the ME sector may be improved. The results of the study for the ME sector in Germany are summarised in this executive summary under the following headings: - Characterising the mechanical engineering sector; - Case studies of energy management in the German mechanical engineering sector; - Evidence of barriers in the German mechanical engineering sector; - The role of energy service companies in the mechanical engineering sector; - Policy implications. (orig.)

Natural analogue study on engineered barriers for underground disposal of radioactive wastes

International Nuclear Information System (INIS)

Araki, K.; Motegi, M.; Emoto, Y.; Kaji, Y.; Ikari, S.; Nada, T.; Watanabe, T.

1989-01-01

This is a report to develop the natural analogue methodology for the assessment of the life of the engineered barriers beyond the time period of normal experiments, 1000 years, for the disposal of low-level radioactive wastes with activity levels greater than those of wastes acceptable for shallow land burial in Japan. Geological and archeological events and objects available for the assessment of the possible life of each engineered barrier are surveyed. Taking heavy precipitation into account in Japan, a long-term, zero-release engineered barrier system using long-term durable materials based on the natural analogue events and objects is proposed along with the conventional type of water permeable engineered barrier system. The combination of the material quality and the environment that could be achieved within the repository is important for the long-term durability of the engineered barrier material. It is proposed that for the natural analogue study a physico-chemical methodology, which may be referred to as the physico-chemical natural history, is necessary to get parameters from the natural analogue events for the long-term assessment of the disposal system

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

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)

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.

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.

Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system

International Nuclear Information System (INIS)

Marty, N.

2006-11-01

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

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.

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.

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.

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.

Synthesis of a Biglucoside and Its Application as Montmorillonite Hydration Inhibitor

Directory of Open Access Journals (Sweden)

Xin-chun Zhang

2014-01-01

Full Text Available A biglucoside (BG was synthesized with glucose and epichlorohydrin as raw materials. The inhibition of BG against montmorillonite swelling was investigated by various methods including montmorillonite linear expansion test, mud ball immersing test, thermogravimetric analysis, and scanning electron microscopy. The results show that the BG has good inhibition ability to the hydration swelling and dispersion of montmorillonite. Under the same condition, the linear expansion ratio of montmorillonite in BG solution is much lower than that of MEG. The particle distribution measurement, thermogravimetric analysis, FT-IR, and scanning electron microscopy results all prove the efficient inhibition of BG.

Engineered surface barriers for waste disposal sites: lysimeter facility design and construction

International Nuclear Information System (INIS)

Phillips, S.J.; Ruben, M.S.; Kirkham, R.R.

1988-01-01

A facility to evaluate performance of engineered surface carriers for confinement of buried wastes has been designed, constructed, and operations initiated. The Field Lysimeter Test Facility is located at the US Department of Energy's Hanford Site in Richland, Washington. The facility consists of 18 one-dimensional drainage and weighing lysimeters used to evaluate 7 replicated barrier treatments. Distinct layers of natural earth materials were used to construct layered soil and rock barriers in each lysimeter. These barrier designs are capable in principal of significantly reducing or precluding infiltration of meteoric water through barriers into underlying contaminated zones. This paper summarizes salient facility design and construction features used in testing of the Hanford Site's engineered surface barriers

Remediation of arsenic-contaminated groundwater using media-injected permeable reactive barriers with a modified montmorillonite: sand tank studies.

Science.gov (United States)

Luo, Ximing; Liu, Haifei; Huang, Guoxin; Li, Ye; Zhao, Yan; Li, Xu

2016-01-01

A modified montmorillonite (MMT) was prepared using an acid activation-sodium activation-iron oxide coating method to improve the adsorption capacities of natural MMTs. For MMT, its interlamellar distance increased from 12.29 to 13.36 Å, and goethite (α-FeOOH) was intercalated into its clay layers. Two novel media-injected permeable reactive barrier (MI-PRB) configurations were proposed for removing arsenic from groundwater. Sand tank experiments were conducted to investigate the performance of the two MI-PRBs: Tank A was filled with quartz sand. Tank B was packed with quartz sand and zero-valent iron (ZVI) in series, and the MMT slurry was respectively injected into them to form reactive zones. The results showed that for tank A, total arsenic (TA) removal of 98.57% was attained within the first 60 mm and subsequently descended slowly to 88.84% at the outlet. For tank B, a similar spatial variation trend was observed in the quartz sand layer, and subsequently, TA removal increased to ≥99.80% in the ZVI layer. TA removal by MMT mainly depended on both surface adsorption and electrostatic adhesion. TA removal by ZVI mainly relied on coagulation/precipitation and adsorption during the iron corrosion. The two MI-PRBs are feasible alternatives for in situ remediation of groundwater with elevated As levels.

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.)

Montmorillonite ameliorates hyperthyroidism of rats and mice attributed to its adsorptive effect.

Science.gov (United States)

Cai, Yan; Meng, Xin-fang; Cao, Yong-xiao; Lu, Hua; Zhu, Shao-fei; Zhou, Liang-zhen

2006-12-03

The present study aims to evaluate the adsorbing effect of montmorillonite on thyroid hormone in the entero-hepatic circulation. The concentration of thyroid hormone in the serum of hyperthyroidism model rats and in solution was measured by radioimmunoassay and ultraviolet spectrometry, respectively. The body weight, temperature, and consumption of food and water were observed in hyperthyroidism model rats. Furthermore, hypoxia tolerance, sodium-pentobarbital-induced sleep time, spontaneous activities were measured on hyperthyroidism model mice after being treated with montmorillonite. Results showed that montmorillonite adsorbed thyroxin (T(4)) and triiodothyronine (T(3)) in vitro. Montmorillonite at dosage of 1.0 g/kg and 0.3 g/kg decreased thyroid hormone levels on hyperthyroidism model rats; Montmorillonite (2.0 g/kg and 0.6 g/kg) prolonged the sleep time, improved the hypoxia tolerant capacity and reduced the spontaneous activities of the hyperthyroidism model mice. These results suggest montmorillonite has anti-hyperthyroidism effect attributed to its adsorptive effect.

Engineered sorbent barriers for low-level waste disposal

International Nuclear Information System (INIS)

Mitchell, S.J.; Freeman, H.D.; Buelt, J.L.

1987-01-01

The Engineered Sorbent Barriers Program at Pacific Northwest Laboratory is developing sorbent materials to prevent the migration of radionuclides from low-level waste sites. These materials would allow water to pass, preventing the bathtub effect at humid sites. Screening studies identified promising sorbent materials for three key radionuclides: for cesium, greensand; for cobalt, activated charcoal; and for strontium, synthetic zeolite of clinoptilolite. Mixtures of these sorbent materials were tested in 0.6-m-diameter columns using radioactive leachates. To simulate expected worst-case conditions, the leachate solution contained the radionuclides, competing cations, and a chelating agent, adjusted to a pH of 5. A sorbent barrier comprised of greensand (1 wt%), activated charcoal (6 wt%), synthetic zeolite (20 wt%), and soil (73 wt%) achieved the decontamination factors necessary to meet the regulatory performance requirements established for this study. Sorbent barriers can be applied to shallow land burial, as backfill around the waste or engineered structures, or as backup to other liner systems. 2 references, 6 figures, 3 tables

Engineered sorbent barriers for low-level waste disposal.

Energy Technology Data Exchange (ETDEWEB)

Freeman, H.D.; Mitchell, S.J.; Buelt, J.L.

1986-12-01

The Engineered Sorbent Barriers Program at Pacific Northwest Laboratory is investigating sorbent materials to prevent the migration of soluble radio nuclides from low-level waste sites. These materials would allow water to pass, preventing the bathtub effect at humid sites. Laboratory studies identifield promising sorbent materials for three key radionuclides: for cesium, greensand; for cobalt, activated charcoal; and for strontium, synthetic zeolite or clinoptilolite. Mixtures of these sorbent materials were tested in 0.6-m-diameter columns using radioactive leachates. To simulate expected worst-case conditions, the leachate solution contained the radionuclides, competing cations, and a chelating agent and was adjusted to a pH of 5. A sorbent barrier comprised of greensand (1 wt%), activated charcoal (6 wt%), synthetic zeolite (20 wt%), and local soil (73 wt%) achieved the decontamination factors necessary to meet the regulatory performance requirements established for this study. Sorbent barriers can be applied to shallow-land burial, as backfill around the waste or engineered structures, or as backup to other liner systems. 7 refs., 14 figs., 12 tabs.

Engineered sorbent barriers for low-level waste disposal

International Nuclear Information System (INIS)

Freeman, H.D.; Mitchell, S.J.; Buelt, J.L.

1986-12-01

The Engineered Sorbent Barriers Program at Pacific Northwest Laboratory is investigating sorbent materials to prevent the migration of soluble radio nuclides from low-level waste sites. These materials would allow water to pass, preventing the bathtub effect at humid sites. Laboratory studies identifield promising sorbent materials for three key radionuclides: for cesium, greensand; for cobalt, activated charcoal; and for strontium, synthetic zeolite or clinoptilolite. Mixtures of these sorbent materials were tested in 0.6-m-diameter columns using radioactive leachates. To simulate expected worst-case conditions, the leachate solution contained the radionuclides, competing cations, and a chelating agent and was adjusted to a pH of 5. A sorbent barrier comprised of greensand (1 wt%), activated charcoal (6 wt%), synthetic zeolite (20 wt%), and local soil (73 wt%) achieved the decontamination factors necessary to meet the regulatory performance requirements established for this study. Sorbent barriers can be applied to shallow-land burial, as backfill around the waste or engineered structures, or as backup to other liner systems. 7 refs., 14 figs., 12 tabs

CHARACTERIZATION OF BENTONITE FOR ENGINEERED BARRIER SYSTEMS IN RADIOACTIVE WASTE DISPOSAL SITES

Directory of Open Access Journals (Sweden)

Dubravko Domitrović

2012-07-01

Full Text Available Engineered barrier systems are used in radioactive waste disposal sites in order to provide better protection of humans and the environment from the potential hazards associated with the radioactive waste disposal. The engineered barrier systems usually contain cement or clay (bentonite because of their isolation properties and long term performance. Quality control tests of clays are the same for all engineering barrier systems. Differences may arise in the required criteria to be met due for different application. Prescribed clay properties depend also on the type of host rocks. This article presents radioactive waste management based on best international practice. Standard quality control procedures for bentonite used as a sealing barrier in radioactive waste disposal sites are described as some personal experiences and results of the index tests (free swelling index, water adsorption capacity, plasticity limits and hydraulic permeability of bentonite (the paper is published in Croatian.

Preparation and Characterization of Modified Montmorillonite/Paraffin Phase Change Microcapsules for Energy Storage

Directory of Open Access Journals (Sweden)

LIN Sen

2017-03-01

Full Text Available The phase change microcapsules of modified montmorillonite/paraffin were prepared by Pickering emulsion method. Analytic techniques of optical microscopy, scanning electron microscopy(SEM, infrared spectroscopy(FTIR, differential scanning calorimetry(DSC and thermogravimetry(TG were utilized for characterizing chemical structure, morphology and thermal properties. Results show that modified montmorillonite as a new type wall material has excellent performance for protecting core material of paraffin. FTIR spectra of phase change of modified montmorillonite/paraffin microcapsules shows that their characteristic peaks match with corresponding peaks of pure paraffin and modified montmorillonite. DSC results indicate that modified montmorillonite/paraffin microcapsules have similar solid-liquid phase change temperature with pure paraffin. The phase transition enthalpy values of microcapsules with paraffin contents varying from 55% to 80% are 110.5-147.2J/g, indicating that microcapsules have excellent thermal storage performance and the phase change properties can be adjusted by changing contents of paraffin. TG results confirm that modified montmorillonite/paraffin microcapsules have outstanding thermal stability. The presented study indicates that modified montmorillonite is a suitable wall material for preparing paraffin microcapsule. Modified montmorillonite/paraffin microcapsules have advantages of low cost and high performance with a great application potential in the field of thermal storage.

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)

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 ...

The Blood-Brain Barrier: An Engineering Perspective

Directory of Open Access Journals (Sweden)

Andrew eWong

2013-08-01

Full Text Available It has been more than 100 years since Paul Ehrlich reported that various water-soluble dyes injected into the circulation did not enter the brain. Since Ehrlich’s first experiments, only a small number of molecules, such as alcohol and caffeine have been found to cross the blood-brain barrier, and it remains the major roadblock to treatment of many central nervous system diseases. At the same time, many central nervous system diseases are associated with disruption of the blood-brain barrier that can lead to changes in permeability, modulation of immune cell transport, and trafficking of pathogens into the brain. Therefore advances in our understanding of the structure and function of the blood-brain barrier are key to advances in treatment of a wide range of central nervous system diseases. Over the past 10 years it has become recognized that the blood-brain barrier is a complex dynamic system that involves biomechanical and biochemical signaling between the vascular system and the brain. Here we reconstruct the structure, function, and transport properties of the blood-brain barrier from an engineering perspective. New insight into the physics of the blood-brain barrier could ultimately lead to clinical advances in the treatment of central nervous system diseases.

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)

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

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.

Improved Barriers to Turbine Engine Fragments: Interim Report II

National Research Council Canada - National Science Library

Shockey, Donald

1999-01-01

... the effects of uncontained engine bursts. SRI International is evaluating the ballistic effectiveness of fabric structures made from advanced polymers and developing a computational ability to design fragment barriers...

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.}

Influence of temperature on pentavalent Np Sorption and desorption onto Goethite, Montmorillonite

International Nuclear Information System (INIS)

Vial, M.A.; Sherman, C; Czerwinski, K.R.; Reed, D.

2002-01-01

Yucca Mountain Site has been selected by the United States Department of Energy as the repository for disposing the US HLW. The performance allocation analysis on a multi-barrier system for high-level radioactive waste disposal has pointed 237 Np as the dominant hazard at the inlet of the biosphere [1J. 2JNp is present in high-level radioactive wastes (HLW), although in smaller amounts in comparison to other radionuclides. Because of its long half-life of 2.14 million years and its mobile nature under aerobic conditions due to the high chemical stability of its pentavalent state, it is considered a possible long-term pollutant of the ecosystem. Understanding Np behavior is required in order to quantitatively describe its transport in surface groundwater systems. In the repository, many components are known to play an important role in Np and other actinides speciation through adsorption-, complexation-, dissolution-, precipitation- and, colloids or pseudocolloids generation reactions [1]. Inorganic Ligands (C0 3 - , OH - ), present in nearly all natural water at various degree, and organic ligands (humic acid) can react with Np and consequently affect its leachability through the formation of numerous compounds. The solubility limits of radionuclides may act as an initial barrier to radionuclide migration from the potential repository at Yucca Mountain for some radionuclides. However, once radionuclides have dissolved in water infiltrating the site, sorption of these radionuclides onto the surrounding mineral phases becomes a potentially important second barrier. The study of retardation of Np and other key actinides is of major importance in assessing the performance of the potential repository. Among the soil of interest montmorillonite and iron-based materials have generated lots of researches. Nagasaki et al. [2] recent researches on sorption equilibrium and kinetics of NpO 2 + on dispersed particles of Na-montmorillonite and Na-illite (batch experiments at p

Functions of an engineered barrier system for a nuclear waste repository in basalt

International Nuclear Information System (INIS)

Coons, W.E.; Moore, E.L.; Smith, M.J.; Kaser, J.D.

1980-01-01

Defined in this document are the functions of components selected for an engineered barrier system for a nuclear waste repository in basalt. The definitions provide a focal point for barrier material research and development by delineating the purpose and operative lifetime of each component of the engineered system. A five-component system (comprised of waste form, canister, buffer, overpack, and tailored backfill) is discussed in terms of effective operation throughout the course of repository history, recognizing that the emplacement environment changes with time. While components of the system are mutually supporting, redundancy is provided by subsystems of physical and chemical barriers which act in concert with the geology to provide a formidable barrier to transport of hazardous materials to the biosphere. The operating philosophy of the conceptual engineered barrier system is clarified by examples pertinent to storage in basalt, and a technical approach to barrier design and material selection is proposed. A method for system validation and qualification is also included which considers performance criteria proposed by external agencies in conjunction with site-specific models and risk assessment to define acceptable levels of system performance

IPR Barriers in Collaboration between University and Engineering Industry in Sweden

OpenAIRE

Huang, Wenting

2011-01-01

This thesis examines the barriers, especially intellectual property rights concerned that inhibit industry academia collaboration. By analyzing Swedish firms in the engineering industry, I explore the influence of IPR barrier on firms’ benefits, short- and long-term respectively from university-industry interaction. Three hypotheses are suggested to investigate the relationship between IPR barriers, firm categories, short-term benefits and long-term benefits. The results illustrate different ...

Environmental Barrier Coatings for Turbine Engines: A Design and Performance Perspective

Science.gov (United States)

Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis; Smialek, James L.; Miller, Robert A.

2009-01-01

Ceramic thermal and environmental barrier coatings (TEBC) for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating long-term durability remains a major concern with the ever-increasing temperature, strength and stability requirements in engine high heat-flux combustion environments, especially for highly-loaded rotating turbine components. Advanced TEBC systems, including nano-composite based HfO2-aluminosilicate and rare earth silicate coatings are being developed and tested for higher temperature capable SiC/SiC ceramic matrix composite (CMC) turbine blade applications. This paper will emphasize coating composite and multilayer design approach and the resulting performance and durability in simulated engine high heat-flux, high stress and high pressure combustion environments. The advances in the environmental barrier coating development showed promise for future rotating CMC blade applications.

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.

[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.

Preparation, characterization, mechanical, barrier and antimicrobial properties of chitosan/PVOH/clay nanocomposites.

Science.gov (United States)

Giannakas, Aris; Vlacha, Maria; Salmas, Constantinos; Leontiou, Areti; Katapodis, Petros; Stamatis, Haralambos; Barkoula, Nektaria-Marianthi; Ladavos, Athanasios

2016-04-20

In the current study low molecular weight poly(vinylalcohol) (PVOH) was used to prepare chitosan/PVOH blends and chitosan/PVOH/montmorillonite nanocomposites via a reflux - solution - heat pressing method. The effect of PVOH content and montmorillonite type (hydrophylic vs. organically modified) on the morphology, mechanical, thermomechanical, barrier and antimicrobial properties of the obtained polymer blends and nanocomposite films was studied. Higher amounts of PVOH (20 and 30%) resulted in plasticization of the films, with an increase in the elongation at break and decrease of the stiffness and the strength while effective blending between chitosan and PVOH chains was observed based on the XRD and DMA findings. Addition of PVOH was beneficial for water and oxygen barrier properties of the obtained films while it did not influence the antimicrobial activity of films against the growth of Escherichia coli. Intercalated structures were obtained after the addition of hydrophilic and organo-modified clays leading into stiffening of the nano-modified films and enhancement of their barrier and antimicrobial properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Engineered Barrier System Degradation, Flow, and Transport Process Model Report

Energy Technology Data Exchange (ETDEWEB)

E.L. Hardin

2000-07-17

The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II).

Engineered Barrier System Degradation, Flow, and Transport Process Model Report

International Nuclear Information System (INIS)

E.L. Hardin

2000-01-01

The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II)

Mössbauer study of pH dependence of iron-intercalation in montmorillonite

Energy Technology Data Exchange (ETDEWEB)

Kuzmann, E., E-mail: kuzmann@caesar.elte.hu [Eötvös Loránd University, Institute of Chemistry (Hungary); Garg, V. K.; Singh, H.; Oliveira, A. C. de; Pati, S. S. [University of Brasília, Institute of Physics (Brazil); Homonnay, Z.; Rudolf, M. [Eötvös Loránd University, Institute of Chemistry (Hungary); Molnár, Á. M.; Kovács, E. M. [University of Debrecen, Imre Lajos Isotope Laboratory, Department of Colloid and Environmental Chemistry (Hungary); Baranyai, E. [University of Debrecen, Department of Inorganic and Analytical Chemistry (Hungary); Kubuki, S. [Tokyo Metropolitan University, Department of Chemistry (Japan); Nagy, N. M.; Kónya, J. [University of Debrecen, Imre Lajos Isotope Laboratory, Department of Colloid and Environmental Chemistry (Hungary)

2016-12-15

{sup 57}Fe Mössbauer spectroscopy and XRD have successfully been applied to show the incorporation of Fe ion into the interlayer space of montmorillonite via treatment with FeCl {sub 3} in acetone. The 78K {sup 57}Fe Mössbauer spectra of montmorillonite samples reflected magnetically split spectrum part indicating the intercalation of iron into the interlayer of montmorillonite via the treatment with FeCl {sub 3}+acetone and washed with water until the initial pH=2.3 increased to pH=4.14. It was found that the occurrence of intercalated iron in the form of oxide-oxihydroxide in montmorillonite increases with the pH. Intercalation was confirmed by the gradual increase in the basal spacing d{sub 001} with pH.

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

Energy Technology Data Exchange (ETDEWEB)

Marty, N

2006-11-15

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

The swelling behavior of montmorillonite as affected by the grain size by in situ X-ray diffraction experiments

International Nuclear Information System (INIS)

Morodome, S.; Kawamura, K.; Owada, H.; Yahagi, R.; Kobayashi, I.

2012-01-01

Document available in extended abstract form only. In many existing researches, the swelling behavior and impermeability of smectitic engineered barrier materials in disposal facilities of radioactive waste was investigated. In the RWMC-project, the effect of smectite content on the mechanical and hydraulic behavior of smectitic materials is investigated and modeled to introduce into THMC analysis. However, since smectite is a natural resource, physical and chemical properties are different with places of production. In order to model the swelling behavior and impermeability of smectitic materials, not only the smectite content but also layer charge and crystal size will be the primary factors. In addition, smectite types and impurity minerals contents or soluble salts affect bentonite characteristic, as well. In this research, in order to focus on the effect of grain size of smectite, the swelling behavior of smectitic materials which are the same place of production but are different grain size were investigated. The smectitic material used in this study was Kunipia-F (Kunimine Industry Co. Ltd., Japan), which is from the Tukinuno Mine, Yamagata prefecture, Japan, and is purified montmorillonite produced by hydraulic elutriation. It is considered that the montmorillonite, Kunipia-F, has large crystal size, and for example Kunipia-F is able to make a sheet when drying weak solution. The grain size was conditioned by jet mill pulverizer. The pulverizing was conducted by making each other collide with high speed. The grain size of the intact and pulverized samples was measured by using of the laser scattering particle distribution analyzer and SEM. The swelling behavior was measured by in situ X-ray diffraction using of a sample chamber which can control the temperature and humidity precisely. The result of the laser scattering analysis denoted that the pulverized sample fined down expressly. The difference of the crystal aspect ratio of the pre- and post

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.

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.

Value engineering study for seletion of verticle barrier technology at a Superfund site

International Nuclear Information System (INIS)

Bryan, E.E.; Guglielmetti, J.L.; Butler, P.B.; Brill, M.P.

1997-01-01

A value engineering (VE) study was conducted to identify and evaluate vertical barrier technologies and alignments for a Superfund project in New Castle County, Delaware. The objective was to select and recommend the most appropriate vertical barrier(s) for two separate landfills and a portion of the manufacturing plant on the site. A VE team was assembled to identify and evaluate site specific issues related to effectiveness, constructability and cost for numerous vertical barrier technologies. Several cost-effective alternatives were identified that met project objectives. The VE study concluded that a composite vertical barrier system consisting of a soil-bentonite slurry trench and steel sheet piles would provide effective containment of the North Landfill. Additionally, the geologic confining unit specified in the Record of Decision (ROD) was found to be unsuitable as a vertical barrier key and a more suitable, shallow confining unit was discovered. This paper describes the value engineering process and results of the VE study for one of the landfills

ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

International Nuclear Information System (INIS)

R. Jarek

2005-01-01

The purpose of this model report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The resulting seepage evaporation and gas abstraction models are used in the total system performance assessment for the license application (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2005 [DIRS 173782], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports. To be consistent with other project documents that address features, events, and processes (FEPs), Table 6.14.1 of the current report includes updates to FEP numbers and FEP subjects for two FEPs identified in the technical work plan (TWP) governing this report (BSC 2005 [DIRS 173782]). FEP 2.1.09.06.0A (Reduction-oxidation potential in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.06.0B (Reduction-oxidation potential in Drifts; see Table 6.14-1). FEP 2.1.09.07.0A (Reaction kinetics in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.07.0B (Reaction kinetics in Drifts; see Table 6.14-1). These deviations from the TWP are justified because they improve integration with FEPs documents. The updates

Progress in waste package and engineered barrier system performance assessment and design

International Nuclear Information System (INIS)

Van Luik, A.; Stahl, D.; Harrison, D.

1993-01-01

As part of the U.S. Department of Energy's evaluation of site suitability for a potential high-level radioactive waste repository, long-term interactions between the engineered barrier system and the site must be determined. This requires a waste-package/engineered-system design, a description of the environment around the emplacement zone, and models that simulate operative processes describing these engineered/natural systems interactions. Candidate designs are being evaluated, including a more robust, multi-barrier waste package, and a drift emplacement mode. Tools for evaluating designs, and emplacement mode are the currently available waste-package/engineered-system performance assessment codes development for the project. For assessments that support site suitability, environmental impact, or licensing decisions, more capable codes are needed. Code capability requirements are being written, and existing codes are to be evaluated against those requirements. Recommendations are being made to focus waste-packaging/engineered-system code-development

Surmounting the Barriers: Ethnic Diversity in Engineering Education: Summary of a Workshop

Science.gov (United States)

National Academies Press, 2014

2014-01-01

"Surmounting the Barriers: Ethnic Diversity in Engineering Education" is the summary of a workshop held in September 2013 to take a fresh look at the impediments to greater diversification in engineering education. The workshop brought together educators in engineering from two- and four-year colleges and staff members from the three…

Engineered barrier experiment. Power control and data acquisition systems

International Nuclear Information System (INIS)

Alberdi, J.; Barcala, J.M.; Gamero, E.; Martin, P.L.; Molinero, A.; Navarrete, J.J.; Yuste, C.

1997-01-01

The engineered barrier concept for the storage of radioactive wastes is being tested at almost full scale at CIEMAT facilities. A data acquisition and control is an element of this experiment. This system would be operating for next three years. (Author)

Design and Performance Optimizations of Advanced Erosion-Resistant Low Conductivity Thermal Barrier Coatings for Rotorcraft Engines

Science.gov (United States)

Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

2012-01-01

Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future rotorcraft engine higher fuel efficiency and lower emission goals. For thermal barrier coatings designed for rotorcraft turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability, because the rotorcraft are often operated in the most severe sand erosive environments. Advanced low thermal conductivity and erosion-resistant thermal barrier coatings are being developed, with the current emphasis being placed on thermal barrier coating toughness improvements using multicomponent alloying and processing optimization approaches. The performance of the advanced thermal barrier coatings has been evaluated in a high temperature erosion burner rig and a laser heat-flux rig to simulate engine erosion and thermal gradient environments. The results have shown that the coating composition and architecture optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic oxidation durability

Self-healing thermal barrier coatings; with application to gas turbine engines

NARCIS (Netherlands)

Ponnusami, S.A.

2013-01-01

Thermal Barrier Coating (TBC) systems have been applied in turbine engines for aerospace and power plants since the beginning of the 1980s to increase the energy efficiency of the engine, by allowing for higher operation temperatures. TBC systems on average need to be replaced about four times

Engineered barrier systems (EBS) in the context of the entire safety case

International Nuclear Information System (INIS)

2003-01-01

A joint NEA-EC workshop entitled 'Engineered Barrier Systems (EBS) in the Context of the Entire Safety Case' was organised in Oxford on 25-27 September 2002 and hosted by United Kingdom Nirex Limited. The main objectives of the workshop were to provide a status report on engineered barrier systems in various national radioactive waste management programmes considering deep geological disposal; to establish the value to member countries of a project on EBS; and to define such a project's scope, timetable and modus operandi. This report presents the outcomes of this workshop. (author)

Engineered Barrier Systems (EBS) in the Context of the Entire Safety Case

International Nuclear Information System (INIS)

2005-01-01

A joint NEA-EC workshop entitled ''Engineered Barrier Systems (EBS) in the Context of the Entire Safety Case'' was organised in Oxford on 25-27 September 2002 and hosted by United Kingdom Nirex Limited. The main objectives of the workshop were to provide a status report on engineered barrier systems in various national radioactive waste management programmes considering deep geological disposal; to establish the value to member countries of a project on EBS; and to define such a project scope, timetable and modus operandi. This report presents the outcomes of this workshop. (author)

Effect of humidity and interlayer cation on frictional strength of montmorillonite

Science.gov (United States)

Tetsuka, H.; Katayama, I.; Sakuma, H.; Tamura, K.

2016-12-01

Smectite has been ubiquitously seen in fault gouge (Schleicher et al., 2006; Kuo et al., 2009; Si et al., 2014; Kameda, 2015) and is characteristic by low frictional coefficient (Saffer et al., 2001; Ikari et al., 2007); consequently, it has a key role in fault dynamics. The frictional strength of montmorillonite (a typical type of smectite) is affected by mainly two factors, 1) hydration state and 2) interlayer cation. Previous laboratory experiments have shown that the frictional strength of montmorillonite changes with hydration state (Ikari et al., 2007) and with interlayer cation (Behnsen and Faulkner, 2013). However, experimental study for frictional strengths of interlayer cation-exchanged montmorillonite under controlled hydration state has not been reported. We are developing humidity control system in biaxial friction testing machine and try to investigate the effect of relative humidity and interlayer cation on frictional strength of montmorillonite. The humidity control system consists of two units, 1) the pressure vessel (core holder) unit controlled by a constant temperature and 2) the vapor generating unit controlled by variable temperature. We control relative humidity around sample, which is calculated from the temperature around sample and the vapor pressure at vapor generating unit. Preliminary experiments under controlled humidity show frictional coefficient of montmorillonite decrease with increasing relative humidity. In the meeting, we will report the systematic study of frictional coefficient as function of relative humidity and interlayer cation species.

Diffusion of helium and estimated diffusion coefficients of hydrogen dissolved in water-saturated, compacted Ca-montmorillonite

International Nuclear Information System (INIS)

Higashihara, Tomohiro; Sato, Seichi; Ohashi, Hiroshi; Otsuka, Teppei

2001-01-01

The diffusion coefficients of hydrogen gas dissolved in water-saturated, compacted montmorillonite are required to estimate the performance of bentonite buffer materials for geological disposal of nuclear waste. As part of the effort to determine the diffusion coefficients, the diffusion coefficients of helium in water-saturated, compacted calcium montmorillonite (Ca-montmorillonite) were determined as a function of dry density, 0.78 to 1.37x10 3 kg m -3 , by a transient diffusion method. The diffusion coefficients were from 8.3x10 -10 m 2 s -1 at 0.78x10 3 kgm -3 to 2.8x10 -10 m 2 s -1 at 1.37x10 3 kgm -3 . The data obtained by this diffusion experiment of helium were highly reproducible. The diffusion coefficients of helium in Ca-montmorillonite were somewhat larger than those previously obtained for helium in sodium montmorillonite (Na-montmorillonite). The diffusion coefficients of hydrogen gas in the montmorillonites were roughly estimated using the diffusion coefficients of helium. These estimates were based on assumptions that both helium and hydrogen molecules are non-adsorptive and that the geometric factors in the compacted montmorillonites are approximately the same for diffusion of helium and diffusion of hydrogen. (author)

Engineered passive bioreactive barriers: risk-managing the legacy of industrial soil and groundwater pollution.

Science.gov (United States)

Kalin, Robert M

2004-06-01

Permeable reactive barriers are a technology that is one decade old, with most full-scale applications based on abiotic mechanisms. Though there is extensive literature on engineered bioreactors, natural biodegradation potential, and in situ remediation, it is only recently that engineered passive bioreactive barrier technology is being considered at the commercial scale to manage contaminated soil and groundwater risks. Recent full-scale studies are providing the scientific confidence in our understanding of coupled microbial (and genetic), hydrogeologic, and geochemical processes in this approach and have highlighted the need to further integrate engineering and science tools.

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....

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.

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.

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)

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

ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

Energy Technology Data Exchange (ETDEWEB)

R. Jarek

2005-08-29

The purpose of this model report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The resulting seepage evaporation and gas abstraction models are used in the total system performance assessment for the license application (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input, which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2005 [DIRS 173782], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports. To be consistent with other project documents that address features, events, and processes (FEPs), Table 6.14.1 of the current report includes updates to FEP numbers and FEP subjects for two FEPs identified in the technical work plan (TWP) governing this report (BSC 2005 [DIRS 173782]). FEP 2.1.09.06.0A (Reduction-oxidation potential in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.06.0B (Reduction-oxidation potential in Drifts; see Table 6.14-1). FEP 2.1.09.07.0A (Reaction kinetics in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.07.0B (Reaction kinetics in Drifts; see Table 6.14-1). These deviations from the TWP are justified because they improve integration with FEPs

Experimental Approach of Fault Movement on an Engineered Barrier System

International Nuclear Information System (INIS)

Lee, Minsoo; Choi, Heuijoo; Kim, Heuna

2012-01-01

Safety evaluation of an engineered barrier system against fault movement at underground disposal region for high level waste (HLW) is tried using a miniature bore-shear apparatus. For the purpose, a miniature bore-shear apparatus simulating an EBS (engineered barrier system) was manufactured in 1/30 scale. And using the developed apparatus, bore-shear tests were performed twice. During the tests, pressure variations were checked at 6 points around buffer zone, and then a rotational angle of the test vessel was checked. The achieved pressure data were compared with those from analytical modeling, which is based on Drucker-Prager model. At initial shearing step, high pressure was recorded at some point but it decreased rapidly. For the better understanding of fault movement, the modification of an analytical model and the accumulation of experimental experience were required

Experimental Approach of Fault Movement on an Engineered Barrier System

Energy Technology Data Exchange (ETDEWEB)

Lee, Minsoo; Choi, Heuijoo; Kim, Heuna [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-03-15

Safety evaluation of an engineered barrier system against fault movement at underground disposal region for high level waste (HLW) is tried using a miniature bore-shear apparatus. For the purpose, a miniature bore-shear apparatus simulating an EBS (engineered barrier system) was manufactured in 1/30 scale. And using the developed apparatus, bore-shear tests were performed twice. During the tests, pressure variations were checked at 6 points around buffer zone, and then a rotational angle of the test vessel was checked. The achieved pressure data were compared with those from analytical modeling, which is based on Drucker-Prager model. At initial shearing step, high pressure was recorded at some point but it decreased rapidly. For the better understanding of fault movement, the modification of an analytical model and the accumulation of experimental experience were required.

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.

Thermal barrier coatings - Technology for diesel engines

International Nuclear Information System (INIS)

Harris, D.H.; Lutz, J.

1988-01-01

Thermal Barrier Coatings (TBC) are a development of the aerospace industry primarily aimed at hot gas flow paths in turbine engines. TBC consists of zirconia ceramic coatings applied over (M)CrAlY. These coatings can provide three benefits: (1) a reduction of metal surface operating temperatures, (2) a deterrent to hot gas corrosion, and (3) improved thermal efficiencies. TBC brings these same benefits to reciprocal diesel engines but coating longevity must be demonstrated. Diesels require thicker deposits and have challenging geometries for the arc-plasma spray (APS) deposition process. Different approaches to plasma spraying TBC are required for diesels, especially where peripheral edge effects play a major role. Bondcoats and ceramic top coats are modified to provide extended life as determined by burner rig tests, using ferrous and aluminum substrates

Diffusive Transport of Sulphide through an Engineering Barrier System in a Deep Geological Repository

Science.gov (United States)

Briggs, S. A.; Sleep, B. E.; McKelvie, J. R. M.; Krol, M.

2015-12-01

Bentonite is a naturally occurring clay-rich sediment containing montmorillonite, a smectitic clay mineral that has a high cation exchange capacity and swells upon contact with water. Owing to these characteristics, highly compacted bentonite (HCB) is an often included component of engineered barrier systems (EBS) designed to protect used fuel containers (UFCs) in deep geological repositories (DGR) for high-level nuclear waste. The low water activity and high swelling pressure of HCB suppresses microbial activity and the related production of sulphide that could cause microbiologically influenced corrosion (MIC) of UFCs The Canadian Nuclear Waste Management Organization (NWMO) has chosen a UFC that consists of an inner steel core and outer copper coating which is resistant to corrosion. However, under anaerobic conditions, MIC can still contribute to UFC corrosion if sulphides are present in the groundwater. Therefore the EBS consisting of bentonite blocks and pellets has been designed to impede the movement of sulphides to the UFC. In order to examine the effectiveness of the EBS, a 3D numerical model was developed capable of simulating the diffusive transport of sulphide within the NWMO EBS. The model was developed using COMSOL Multiphysics, a finite element software package and is parametric which allows the impact of different repository layouts to be assessed. The developed model was of the entire NWMO placement room, as well as, a stand-alone UFC and included conservative assumptions such as a fully saturated system and a constant concentration boundary condition. The results showed that the highest sulphide flux occurred at the semi-spherical end caps of the UFC. Further studies examined the effect of sulphide hotspots and fractures, representing possible EBS failure mechanisms. The model results highlight that even with conservative assumptions the chosen EBS will effectively protect the UFC from microbiologically influenced corrosion.

The disposal of Canada's nuclear fuel waste: engineered barriers alternatives

International Nuclear Information System (INIS)

Johnson, L.H.; Tait, J.C.; Shoesmith, D.W.; Crosthwaite, J.L.; Gray, M.N.

1994-01-01

The concept for disposal of Canada's nuclear fuel waste involves emplacing the waste in a vault excavated at a depth of 500 to 1000 m in plutonic rock of the Canadian Shield. The solid waste would be isolated from the biosphere by a multibarrier system consisting of engineered barriers, including long-lived containers and clay and cement-based sealing materials, and the natural barrier provided by the massive geological formation. The technical feasibility of this concept and its impact on the environment and human health are being documented in an Environmental Impact Statement (EIS), which will be submitted for review under the federal Environmental Assessment and Review Process. This report, one of nine EIS primary references, describes the various alternative designs and materials for engineered barriers that have been considered during the development of the Canadian disposal concept and summarizes engineered barrier concepts being evaluated in other countries. The basis for the selection of a reference engineered barrier system for the EIS is presented. This reference system involves placing used CANDU (Canada Deuterium Uranium) fuel bundles in titanium containers, which would then be emplaced in boreholes drilled in the floor of disposal rooms. Clay-based sealing materials would be used to fill both the space between the containers and the rock and the remaining excavations. In the section on waste forms, the properties of both used-fuel bundles and solidified high-level wastes, which would be produced by treating wastes resulting from the reprocessing of used fuel, are discussed. Methods of solidifying the wastes and the chemical durability of the solidified waste under disposal conditions are reviewed. Various alternative container designs are reviewed, ranging from preliminary conceptual designs to designs that have received extensive prototype testing. Results of structural performance, welding and inspection studies are also summarized. The corrosion of

Solvent Free Preparation of p-Cymene from Limonene Using Vietnamese Montmorillonite

DEFF Research Database (Denmark)

Nguyen, Thao-Tran Thi; Duus, Fritz; Le, Thach Ngoc

2013-01-01

p-Cymene, an important intermediate in industrial chemistry, has been prepared in good yields by thermally induced dehydrogenation of limonene under solvent-free reaction conditions using Vietnamese montmorillonite as an efficient green catalyst.......p-Cymene, an important intermediate in industrial chemistry, has been prepared in good yields by thermally induced dehydrogenation of limonene under solvent-free reaction conditions using Vietnamese montmorillonite as an efficient green catalyst....

Montmorillonite dissolution kinetics: Experimental and reactive transport modeling interpretation

Science.gov (United States)

Cappelli, Chiara; Yokoyama, Shingo; Cama, Jordi; Huertas, F. Javier

2018-04-01

The dissolution kinetics of K-montmorillonite was studied at 25 °C, acidic pH (2-4) and 0.01 M ionic strength by means of well-mixed flow-through experiments. The variations of Si, Al and Mg over time resulted in high releases of Si and Mg and Al deficit, which yielded long periods of incongruent dissolution before reaching stoichiometric steady state. This behavior was caused by simultaneous dissolution of nanoparticles and cation exchange between the interlayer K and released Ca, Mg and Al and H. Since Si was only involved in the dissolution reaction, it was used to calculate steady-state dissolution rates, RSi, over a wide solution saturation state (ΔGr ranged from -5 to -40 kcal mol-1). The effects of pH and the degree of undersaturation (ΔGr) on the K-montmorillonite dissolution rate were determined using RSi. Employing dissolution rates farthest from equilibrium, the catalytic pH effect on the K-montmorillonite dissolution rate was expressed as Rdiss = k·aH0.56±0.05 whereas using all dissolution rates, the ΔGr effect was expressed as a non-linear f(ΔGr) function Rdiss = k · [1 - exp(-3.8 × 10-4 · (|ΔGr|/RT)2.13)] The functionality of this expression is similar to the equations reported for dissolution of Na-montmorillonite at pH 3 and 50 °C (Metz, 2001) and Na-K-Ca-montmorillonite at pH 9 and 80 °C (Cama et al., 2000; Marty et al., 2011), which lends support to the use of a single f(ΔGr) term to calculate the rate over the pH range 0-14. Thus, we propose a rate law that also accounts for the effect of pOH and temperature by using the pOH-rate dependence and the apparent activation energy proposed by Rozalén et al. (2008) and Amram and Ganor (2005), respectively, and normalizing the dissolution rate constant with the edge surface area of the K-montmorillonite. 1D reactive transport simulations of the experimental data were performed using the Crunchflow code (Steefel et al., 2015) to quantitatively interpret the evolution of the released cations

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

The role of engineered barriers in spent fuel disposal

International Nuclear Information System (INIS)

Vokal, A.

1997-01-01

Engineered, i.e. man-made, barriers in underground spent fuel disposal include the waste form itself, the fuel cladding, the storage container, and the isolating system made of buffering, filling, and sealing materials. The parameters of and requirements for each of the components are highlighted, and the methodology of materials selection is discussed. (P.A.)

Study on intercalation of ionic liquid into montmorillonite and its property evaluation

International Nuclear Information System (INIS)

Takahashi, Chisato; Shirai, Takashi; Fuji, Masayoshi

2012-01-01

Present study report fabrication of a solid–liquid intercalated compound using montmorillonite and ionic liquid [IL; 1-Butyl-3-methylimidazolium tetrafluoroborate; ([BMIM][BF 4 ])]. The intercalation of IL into the interlayer of montmorillonite was revealed by swelling behavior measured by X-ray diffraction (XRD) and cation exchange capacity (CEC). The crystal swelling structure of intercalation compound was further evidenced by transmission electron microscope (TEM). From these results, the arrangement of [BMIM] + ions (cationic part of IL) into the unit layer were proposed. Furthermore, the montmorillonite showed electrical conductivity with the aid of IL. This demonstrates a successful attempt to fabricate a solid–liquid state nano-structure compound as possible transparent electrically conducting thin film. -- Highlights: ► Direct intercalation of ionic liquid into the montmorillonite was studied. ► The crystal swelling structure in liquid state was successfully characterized by TEM. ► We proposed the atomic arrangement of intercalated compound using ionic liquid. ► Ionic liquid is useful for fabricating an intercalated compound with electrical-conductivity.

Carbon nanotube/paraffin/montmorillonite composite phase change material for thermal energy storage.

Science.gov (United States)

Li, Min; Guo, Qiangang; Nutt, Steven

2017-04-01

A composite phase change material (PCM) comprised of organic montmorillonite (OMMT)/paraffin/grafted multi-walled nanotube (MWNT) is synthesized via ultrasonic dispersion and liquid intercalation. The microstructure of the composite PCM has been characterized to determine the phase distribution, and thermal properties (latent heat and thermal conductivity) have been measured by differential scanning calorimetry (DSC) and a thermal constant analyzer. The results show that paraffin molecules are intercalated in the montmorillonite layers and the grafted MWNTs are dispersed in the montmorillonite layers. The latent heat is 47.1 J/g, and the thermal conductivity of the OMMT/paraffin/grafted MWNT composites is 34% higher than that of the OMMT/paraffin composites and 65% higher than that of paraffin.

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

Clays in natural and engineered barriers for radioactive waste confinement

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-07-01

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

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

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

Backfill barriers: the use of engineered barriers based on geologic materials to assure isolation of radioactive wastes in a repository

International Nuclear Information System (INIS)

Apps, J.A.; Cook, N.G.W.

1981-06-01

A preliminary assessment is made to show that canisters fabricated of nickel-iron alloys, and surrounded by a suitable backfill, may produce an engineered barrier where the canister material is thermodynamically stable with respect to its environment. As similar conditions exist in nature, the performance of such systems as barriers to isolate radionuclides can be predicted over very long periods, of the order of 10 6 years

Evaluation of particle release from montmorillonite gel by flowing groundwater based on the DLVO theory

International Nuclear Information System (INIS)

Kurosawa, Susumu; Nagasaki, Shinya; Tanaka, Satoru

2007-01-01

Theoretical study has been performed to clarify the ability of colloid release form the montmorillonite gel by the flowing groundwater. Evaluation of montmorillonite colloidal particles release from the bentonite buffer material is important for the performance assessment of radioactive waste disposal because the colloids may influence the radionuclide transport. In this study, the minimum groundwater flow rate required to tear off montmorillonite particles from surface of bentonite buffer was estimated from the shear stress on the gel front, which was calculated by the DLVO theory. The estimated shear force was converted to corresponding groundwater velocity by using Stoke's equation. The results indicated that groundwater velocity in a range of about 10 -5 to 10 -4 m/s would be necessary to release montmorillonite particles. This range is higher than the groundwater flow velocity found generally in deep geological media in Japan. This study suggests that the effect of montmorillonite particles release from the bentonite buffer on radionuclide transport is likely to be negligible in the performance assessment of high-level radioactive waste geological disposal. (author)

Review of durability of cementitious engineered barriers in repository environments

International Nuclear Information System (INIS)

Parrott, L.J.; Lawrence, C.D.

1992-01-01

This report is concerned with the durability of cementitious engineered barriers in a repository for low and intermediate level nuclear waste. Following the introduction the second section of the review identifies the environmental conditions associated with a deep, hard rock repository for ILW and LLW that are relevant to the durability of cementitious barriers. Section three examines the microstructure and macrostructure of cementitious materials and considers the physical and chemical processes of radionuclide immobilization. Potential repository applications and compositions of cementitious materials are reviewed in Section four. The main analysis of durability is dealt with in Section five. The different types of cementitious barrier are considered separately and their most probable modes of degradation are analysed. Concluding remarks that highlight critical technical matters are given in Section six. (author)

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.

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.

Application of simplified desorption method to sorption study. (2) Sorption of neptunium (V) on montmorillonite-based mixtures

International Nuclear Information System (INIS)

Kozai, Naofumi; Ohnuki, Toshihiko

2013-01-01

To elucidate the sorption behaviors of radionuclides in multi-mineral systems and the mutual effects of minerals on the sorption, this paper carried out the sorption and desorption experiments of neptunium(V) on montmorillonite-based two-mineral mixtures. The Np sorbed on montmorillonite at pH from 4 to 8 was desorbed with 1M KCl solutions, indicating that the sorption was cation exchange. The Np sorbed on apatite and calcite was nondesorbable with 1M KCl solutions, which is in harmony with the knowledge that Np forms strong complexes with the phosphate groups of apatite and the carbonate groups of calcite. This study utilized these clear distinguishes of the desorption behaviors for examining the two-mineral systems. In montmorillonite-apatite mixtures, the sorption on the montmorillonite was decreased and Np was accumulated on the apatite. In montmorillonite-calcite mixtures, the sorption on the montmorillonite was decreased due to the interference by the calcium and carbonate ions dissolved from calcite while no accumulation of Np to calcite was observed. (author)

Engineered barrier construction in salt rock. Final report of project phase 2. Period covered: 1 July 1989 - 31 December 1992

International Nuclear Information System (INIS)

Stockmann, N.; Beinlich, A.; Droste, J.; Flach, D.; Glaess, F.; Jockwer, N.; Krogmann, P.; Miehe, R.; Moeller, J.; Schwaegermann, F.; Wallmueller, R.; Walter, F.; Yaramanci, U.

1994-01-01

The project report presents and explains data obtained by a specific measuring programme, giving evidence of the sealing efficiency of an engineered barrier comprising abutment, long-term barrier, and hydraulic short-term barrier, the sealing performance having been verified for shorter and longer periods of time ( up to approx. 500 years). Specific computer codes have been applied for computing and verifying the long-term efficiency of the complex engineered barrier system (artificial structures and surrounding rock). The technical feasibility and the performance of an engineered barrier for reliable sealing of a radwaste repository is thus demonstrated at a scale of 1:1 at the site of the Asse mine [de

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.

Chemical interaction of tetravalent actinides simulators and the engineering barrier

International Nuclear Information System (INIS)

Chain, Pablo; Alba, Maria D.; Castro, Miguel A.; Pavon, Esperanza; Mar Orta, M.

2010-01-01

Document available in extended abstract form only. The Deep Geological Repository (DGR) is the most internationally accepted option for the storage of high radioactive wastes. This confinement is based on the Multi-barrier Concept where the engineered barrier is a crucial safety wise. Nowadays, bentonite is accepted as the best argillaceous material in the engineered barrier of DGR. Additionally to its well-known physical role, a chemical interaction between lutetium, as actinide simulator, and the smectite has been demonstrated. The existence of a reaction mechanism, which was not previously described, based on the chemical interaction between the lanthanide cations and the orthosilicate anions of the lamellar structure has been identified. This finding has aroused the interest of the scientific community because lanthanides are used as simulators of high activity radionuclide (HAR) in agreement with the guidelines established in the bibliography. It has been observed that in conditions of moderate temperature and pressure a chemical interaction exists between smectites and rare earth elements (RE) and phases of insoluble di-silicate, RE 2 Si 2 O 7 , which would immobilize RE, are generated. It is remarkable that the reaction extends to all the set of the smectites, although they do not display the same reactivity, the saponite being the most reactive. The main isotopes present in the HLW belong to the actinide elements Np, Pu, Am and Cm, in addition to uranium generated by neutron capture during the fuel combustion process. The study of the mobilization of actinide (IV) thorough the bentonite barrier is limited because of their radioactivity. However, U(IV), Np(IV), Pu(IV) and Th(IV) can be simulated by the stable isotopes of the Zr(IV) and Hf(IV), because they exhibit ionic radius and physicochemical properties very similar to those of the actinide elements. It is the main objective of this research to investigate the chemical interaction of Zr(IV) as actinide

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.

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.

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.

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.

Development of engineered barrier

Energy Technology Data Exchange (ETDEWEB)

Chun, Kwan Sik; Cho, Won Jin; Lee, Jae Owan; Kim, Seung Soo; Kang, Mu Ja

1999-03-01

Engineered barrier development was carried out into the three research fields : waste form, disposal container, and buffer. The waste form field dealt with long-term leaching tests with borosilicate waste glasses surrounded by compacted bentonite. The leach rate decreased with increasing time, and was higher for the waste specimen rich in U and Na. In the container field, preliminary concepts of disposal containers were recommended by conducting structural analysis, thermal analysis, and shielding analysis, and major properties of stainless steel, copper, and titanium as a container material were surveyed. The sensitization degrees of SUS 316 and316L were lower than those of SUS 304 and 304L, respectively. The crevice corrosion of sensitized stainless steel was sensitive to the content of salt. Researches into the buffer included establishment of its performance criteria followed by investigating major properties of buffer using potential material in Korea. Experiments were made for measuring hydraulic conductivities, swelling properties, mechanical properties, thermal conductivities, pore-water chemistry properties, and adsorption properties was also investigated. (author)

Development of engineered barrier

International Nuclear Information System (INIS)

Chun, Kwan Sik; Cho, Won Jin; Lee, Jae Owan; Kim, Seung Soo; Kang, Mu Ja

1999-03-01

Engineered barrier development was carried out into the three research fields : waste form, disposal container, and buffer. The waste form field dealt with long-term leaching tests with borosilicate waste glasses surrounded by compacted bentonite. The leach rate decreased with increasing time, and was higher for the waste specimen rich in U and Na. In the container field, preliminary concepts of disposal containers were recommended by conducting structural analysis, thermal analysis, and shielding analysis, and major properties of stainless steel, copper, and titanium as a container material were surveyed. The sensitization degrees of SUS 316 and 316L were lower than those of SUS 304 and 304L, respectively. The crevice corrosion of sensitized stainless steel was sensitive to the content of salt. Researches into the buffer included establishment of its performance criteria followed by investigating major properties of buffer using potential material in Korea. Experiments were made for measuring hydraulic conductivities, swelling properties, mechanical properties, thermal conductivities, pore-water chemistry properties, and adsorption properties was also investigated. (author)

Bentonite engineered barrier building method for radioactive waste on sub-surface disposal test project

International Nuclear Information System (INIS)

Mori, Takuo; Takahashi, Shinichi; Takeuchi, Kunifumi; Namiki, Kazuto

2008-01-01

The engineering barriers such as clay and concrete materials are planned to use for covering radioactive waste in cavern-type disposal facility. The requirement to clay barrier is very low permeability, which could be satisfied by high density Bentonite, and such a compaction method will be needed. Two methods, compaction and air shot, were tested in engineering scale for constructing a high-density clay barrier. Two types of compaction equipments, 'Teasel plate' and 'Plate compacter', were developed and engineering scale experiments were performed for compacting Bentonite only and Bentonite-sand-aggregate mixture. As a result, the Teasel plate can reach higher density Bentonite in relatively short time in comparison to other equipments. While, regarding air shot method, an air-shot machine in a tunnel construction site was tested by different water adding methods (wet, dry, and half wet). It is concluded that the dry and half wet constructing methods will achieve reasonable workability. As a result, the best construction option can be chosen according to the locations of radioactive waste facility. (author)

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 ...

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.

Studies on an advanced repository system with enhanced engineered barriers (a framework)

International Nuclear Information System (INIS)

Fujiwara, A.; Tashiro, S.; Ikari, S.; Suzuki, A.

1993-01-01

In order to propose advanced designs of repositories with enhanced engineered barriers of relatively high radioactive wastes such as burnable poisons, channel boxes, control rods and highly irradiated metals, studies started in 1987 and completed the first phase in 1992. This paper presents the framework and brief results of the first phase. The studies set preliminary design concepts of the repositories with various combinations with engineered barriers and natural barriers for different models and locations such as a silo type in shallow land or a tunnel type in intermediate depth. Through the designs, four component technics were picked up and studied for (1) construction of the components in repository; (2) performance evaluation to realize repository design; (3) improvement of circumstances inside or around repository; and (4) surveillance of repository performance to realize the repository designs. Finally, some repository systems were provided using obtained results, and then the applicability and the economy were evaluated. The studies will continue to the second phase focusing on the long-term performance of the repositories

Monitoring long-term evolution of engineered barrier systems using magnets: Magnetic response.

Science.gov (United States)

Rigonat, N; Isnard, O; Harley, S L; Butler, I B

2018-01-05

Remote and non-destructive monitoring of the stability and performance of Engineered Barrier Systems for Geological Disposal Facility of is gaining considerable importance in establishing the safety cases for Higher Activity Wastes disposal. This study offers an innovative use of mineral magnetism for monitoring groundwater saturation of the barrier. Four mixtures of permanent magnets (Nd-Fe-B, coated and uncoated; SmCo and AlNiCo) and bentonite were reacted for 4, 8 and 12 months with mildly-saline, high-pH leachates, representing the fluids saturating a time-evolved engineered barrier. Coupled hysteresis and thermomagnetic analyses demonstrate how Nd-Fe-B feature a time-dependent transition from square-like ferromagnetic to superparamagnetic loop via pot-bellied and wasp-waist loops, whereas SmCo and AlNiCo do not show so extensive corrosion-related variations of the intrinsic and extrinsic magnetic properties. This study allowed to identify magnetic materials suitable for shorter- (Nd-Fe-B) and longer-term (SmCo and AlNiCo) monitoring purposes. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Materials characterization center workshop on corrosion of engineered barriers

Energy Technology Data Exchange (ETDEWEB)

Merz, M.D.; Zima, G.E.; Jones, R.H.; Westerman, R.E.

1981-03-01

A workshop on corrosion test procedures for materials to be used as barriers in nuclear waste repositories was conducted August 19 and 20, 1980, at the Battelle Seattle Research Center. The purpose of the meeting was to obtain guidance for the Materials Characterization Center in preparing test procedures to be approved by the Materials Review Board. The workshop identified test procedures that address failure modes of uniform corrosion, pitting and crevice corrosion, stress corrosion, and hydrogen effects that can cause delayed failures. The principal areas that will require further consideration beyond current engineering practices involve the analyses of pitting, crevice corrosion, and stress corrosion, especially with respect to quantitative predictions of the lifetime of barriers. Special techniques involving accelerated corrosion testing for uniform attack will require development.

Materials characterization center workshop on corrosion of engineered barriers

International Nuclear Information System (INIS)

Merz, M.D.; Zima, G.E.; Jones, R.H.; Westerman, R.E.

1981-03-01

A workshop on corrosion test procedures for materials to be used as barriers in nuclear waste repositories was conducted August 19 and 20, 1980, at the Battelle Seattle Research Center. The purpose of the meeting was to obtain guidance for the Materials Characterization Center in preparing test procedures to be approved by the Materials Review Board. The workshop identified test procedures that address failure modes of uniform corrosion, pitting and crevice corrosion, stress corrosion, and hydrogen effects that can cause delayed failures. The principal areas that will require further consideration beyond current engineering practices involve the analyses of pitting, crevice corrosion, and stress corrosion, especially with respect to quantitative predictions of the lifetime of barriers. Special techniques involving accelerated corrosion testing for uniform attack will require development

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

Montmorillonite Supported Titanium/Antimony Catalyst:Preparation, Characterization and Immobilization

Institute of Scientific and Technical Information of China (English)

CHEN Guiyong; WANG Xiaoqun; ZHAO Chuan; DU Shanyi

2014-01-01

Montmorillonite supported titanium (Ti-MMT) or antimony catalyst (Sb-MMT) has been a hot area of research on preparing polyethylene terephthalate/montmorillonite (PET/MMT) nanocomposites by in situ polymerization. So removal of Ti or Sb from Ti-MMT or Sb-MMT is not expected during in situ polymerization. Studies on immobilization of Ti or Sb on Ti-MMT or Sb-MMT are seldom reported. In this work, a series of montmorillonite supported catalysts of titanium (Ti-MMT) or antimony (Sb-MMT) and co-intercalated montmorillonite of titanium and antimony (Ti/Sb-MMT) were prepared by (1) the reaction of sodium bentonite suspension with intercalating solution containing titanium tetrachloride and/or antimony chloride, and (2) drying or calcinating the products at different temperature (100, 150, 240, 350 and 450℃). The physicochemical properties of these MMT supported catalysts were studied by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma optical emission spectrometer (ICPOES), N2 adsorption/desorption isotherms, UV-visible diffuse reflectance spectroscopy(UV-vis) and transmission electron microscopy (TEM). The immobile character of Ti or Sb on MMT supported catalysts was evaluated by a two-step method in deionized water or ethylene glycol. Several results were obtained, i e, (a) during the preparation, with an increase in drying or calcinating temperature, the amount of titanium and/or antimony species remained on these MMT supported catalysts decreased, (b) the experiments about immobile character of Ti or/and Sb showed that with an increase in drying or calcinating temperature, the immobilization of Ti and/or Sb species remained on these MMT supported catalysts increased gradually, (c) Ti-MMT calcinated at 450℃had the biggest pore volume, which means Ti-MMT had the best adsorption application prospect.

The influence of montmorillonite content on the kinetics of curing of epoxy nanocomposites

Directory of Open Access Journals (Sweden)

Jovičić Mirjana C.

2012-01-01

Full Text Available In this work, the attention was paid at the investigation of montmorillonite dispersion in epoxy/amine systems due to improved final properties of the nanocomposites. The influence of different montmorillonite content on the kinetics of curing of epoxy/Jeffamine D-230 systems was followed by differential scanning calorimetry (DSC. The curing of epoxy nanocomposites was performed using dynamic regime at three different heating rates: 5, 10 and 20°C/min. Three isoconversional methods were applied: two integral (Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose methods and one differential (Friedman method. The presence of montmorillonite (MMT causes the beginning of curing at lower temperatures. The shape of the DSC curves has been changed by the addition of MMT, supporting the hypothesis of a change in the reaction mechanism. For hybrids with 3 and 5 wt.% of MMT, the Eα dependence is very similar to those found for the reference system (epoxy/Jeffamine D-230 for the curing degree less than 60%. The hybrid with 10 wt.% of MMT has lower energy activation in regard to the referent system without montmorillonite. Greater differences are observed in the second part of the reaction, where it is known that the curing process is more controlled by diffusion (α>0.60. The Ea value increases at the end of the reaction (α→1, which was observed for all systems, and is more pronounced in the presence of montmorillonite. [Projekat Ministarstva nauke Republike Srbije, br. III45022

Synthesis and Optical Properties of MnS–ZnS and MnS–CdS Nanoparticles in Montmorillonite.

Science.gov (United States)

Kabilaphat, Jirabhorn; Poosimma, Poonsuk; Khaorapapong, Nithima; Intachai, Sonchai; Ogawa, Makoto

2017-02-01

The incorporation of metal sulfide mixture, manganese sulfide and zinc sulfide (MnS–ZnS) or manganese sulfide and cadmium sulfide (MnS–CdS), in two types of montmorillonites (sodium montmorillonite and cetyltrimethylammonium modified montmorillonite) was investigated. The hybrids were characterized by powder X-ray diffraction, thermogravimetric-differential thermal analysis, transmission electron microscopy (TEM), and Raman, UV-visible and photoluminescence spectroscopies. The experimental evidences such as the expansion of the interlayer spaces and the presence of the absorption and photoluminescence due to MnS, ZnS and/or CdS revealed that the mixed metal sulfides formed in the interlayer space of montmorillonites. TEM images of the hybrids showed diskor plate-shaped nanoparticles with a mean diameter of ca. 2 nm. The increase of the luminescence intensities of the hybrids was assumed to be caused by quantum confinement effect in the interlayer space of montmorillonite.

Adsorption of cadmium onto Al{sub 13}-pillared acid-activated montmorillonite

Energy Technology Data Exchange (ETDEWEB)

Yan Liangguo [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Shan Xiaoquan [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)], E-mail: xiaoquan@rcees.ac.cn; Wen Bei [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Owens, Gary [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes Campus, Mawson Lakes, Boulevard, South Australia 5095 (Australia)

2008-08-15

The optimal preparation conditions for Al{sub 13}-pillared acid-activated Na{sup +}-montmorillonite (Al{sub 13}-PAAMt) were (1) an acid-activated Na{sup +}-montmorillonite (Na{sup +}-Mt) solution of pH 3.0, (2) a OH{sup -}/Al{sup 3+} molar ratio of 2.4 and (3) Al{sup 3+}/Na{sup +}-Mt ratio of 1.0 mmol g{sup -1}. The effects of OH{sup -}/Al{sup 3+} and Al{sup 3+}/Na{sup +}-Mt ratios on the adsorption of Cd{sup 2+} onto Al{sub 13}-PAAMt were studied. A comparison of the adsorption of Cd{sup 2+} onto Al{sub 13}-PAAMt, Al{sub 13}-pillared Na{sup +}-montmorillonite (Al{sub 13}-PMt) and Na{sup +}-Mt suggested that Al{sub 13}-PAAMt had higher adsorption affinity for Cd{sup 2+} than the other two adsorbents. A pseudo-second-order model described the adsorption kinetics well. Cadmium adsorption followed the Langmuir two-site equation, while desorption was hysteretic.

Performance of engineered barrier materials in near surface disposal facilities for radioactive waste. Results of a co-ordinated research project

International Nuclear Information System (INIS)

2001-11-01

The primary objectives of the CRP were to: promote the sharing of experiences of the Member States in their application of engineered barrier materials for near surface disposal facilities; help enhance their use of engineered barriers by improving techniques and methods for selecting, planning and testing performance of various types of barrier materials for near surface disposal facilities. The objective of this publication is to provide and overview of technical issues related to the engineered barrier systems and a summary of the major findings of each individual research project that was carried out within the framework of the CRP. This publication deals with a general overview of engineered barriers in near surface disposal facilities, key technical information obtained within the CRP and overall conclusions and recommendations for future research and development activities. Appendices presenting individual research accomplishments are also provided. Each of the 13 appendices was indexed separately

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)

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)

Yucca Mountain engineered barrier system corrosion model (EBSCOM)

International Nuclear Information System (INIS)

King, F.; Kolar, M.; Kessler, J.H.; Apted, M.

2008-01-01

A revised engineered barrier system model has been developed by the Electric Power Research Institute to predict the time dependence of the failure of the drip shields and waste packages in the proposed Yucca Mountain repository. The revised model is based on new information on various corrosion processes developed by the US Department of Energy and others and for a 20-mm-thick waste package design with a double closure lid system. As with earlier versions of the corrosion model, the new EBSCOM code produces a best-estimate of the failure times of the various barriers. The model predicts that only 15% of waste packages will fail within a period of 1 million years. The times for the first corrosion failures are 40,000 years, 336,000 years, and 375,000 years for the drip shield, waste package, and combination of drip shield and the associated waste package, respectively

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.

Studies on the flammability of polypropylene/ammonium polyphosphate and montmorillonite by using the cone calorimeter test

Directory of Open Access Journals (Sweden)

Hanna A.A.

2018-03-01

Full Text Available Fire performance of polypropylene (PP containing different percentages of ammonium polyphosphate (APP with montmorillonite (Mt or treated montmorillonite (MtT was carried out by using the cone calorimeter test (CCT. Different samples from ammonium polyphosphate and montmorillonite were mixed with 90% polypropylene. The characterization of the prepared samples indicates that there is incorporation between the components of the samples. Heat release rate (HRR, peak heat release rate (PHRR, average heat release rate (Av-HRR, and time to ignition (TTI of the samples were obtained from the cone calorimeter test. Also, the fire performance index (FPI and the fire growth rate (FIGRA were calculated. The interpretation of the curves and the parameters results from the cone calorimeter test which indicates that the addition of montmorillonite to APP increases its action as a flame retardant for PP. Moreover, the samples contain acid treatment montmorillonite showed an increase in the efficiency of ammonium polyphosphate when used. This result may be due to an increase in the SiO2 content by acid treatment.

Seawater Durability of Nano-Montmorillonite Modified Single-Lap Joining Epoxy Composite Laminates

OpenAIRE

ULUS, Hasan; KAYBAL, Halil Burak; DEMİR, Okan; TATAR, Ahmet Caner; SENYURT, Muhammed Ali; AVCI, Ahmet

2018-01-01

The objective of this study was to investigate of nano-montmorillonite modified epoxy composite single-lap bonded joints, after being exposed to seawater immersion in order to understand the effect of seawater environment on their performance. To prepare the nano adhesives, nano montmorillonite (2 wt %) was incorporated into epoxy resin. Composite bonded specimens which manufactured with VARIM (Vacuum Assisted Resin Infusion Method) were prepared accordance with ASTM D5868-01 and immersed in ...

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 ...

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)

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)

Carbon nanotubes rooted montmorillonite (CNT-MM) reinforced nanocomposite membrane for PEM fuel cells

International Nuclear Information System (INIS)

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

2012-01-01

Highlights: ► Novel montmorillonite-CNT (MM-CNT) nanohybrid materials were produced by CVD. ► Highly selective crystalline carbon nanotubes were grown over montmorillonite. ► Fabricated Nafion-MM-CNT nanocomposite membrane by solution casting method. ► Homogeneous dispersion of MM-CNT in the Nafion matrix was achieved. ► Combined effect of montmorillonite and CNT improves the thermal stability of Nafion. - Abstract: Nafion based nanocomposite membranes containing montmorillonite-carbon nanotubes (a binary hybrid material) were produced to develop high performance polymer electrolyte fuel cells. Multi walled carbon nanotubes were grown over 20 and 25 wt% iron loaded montmorillonite catalysts by CVD using acetylene as the carbon precursor. Growth experiments were carried out at optimised conditions to obtain highly selective crystalline carbon nanotubes. X-ray diffraction spectra of the catalysts were recorded for the structural characterisation and definition of particle size. The carbon nanotubes obtained were examined by various physico chemical characterisation studies such as SEM, TEM, Raman spectroscopy and TG analyses to understand the morphology and crystallinity of the CNTs. The MM-CNT hybrid material with I D /I G ratio of Raman spectral band as 0.53 represents the high selectivity towards CNTs. Thus the hybrid material produced was considered as the best nanofiller to develop polymer nanocomposites. Nafion based nanocomposite membranes were prepared by adding MM-CNT as nanofiller by solution casting method. A better dispersion of MM-CNT into the Nafion matrix was observed and the addition of the MM-CNT improved the thermal stability of the Nafion membrane.

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

Design of engineered sorbent barriers

International Nuclear Information System (INIS)

Jones, E.O.; Freeman, H.D.

1988-01-01

A sorbent barrier uses sorbent material such as activated carbon or natural zeolites to prevent the migration of radionuclides from a low-level waste site to the aquifer. The sorbent barrier retards the movement of radioactive contaminants, thereby providing time for the radionuclides to decay. Sorbent barriers can be a simple, effective, and inexpensive method for reducing the migration of radionuclides to the environment. Designing a sorbent barrier consists of using soil and sorbent material properties and site conditions as input to a model which will determine the necessary sorbent barrier thickness to meet contaminant limits. The paper covers the following areas: techniques for measuring sorption properties of barrier materials and underlying soils, use of a radionuclide transport model to determine the required barrier thickness and performance under a variety of site conditions, and cost estimates for applying the barrier

Fe(III/TiO2-Montmorillonite Photocatalyst in Photo-Fenton-Like Degradation of Methylene Blue

Directory of Open Access Journals (Sweden)

Is Fatimah

2015-01-01

Full Text Available A photodegradation process of methylene blue (MB in aqueous solution using Fe(III/TiO2-montmorillonite photocatalyst is presented. The photocatalyst material was prepared using Indonesian natural montmorillonite in TiO2 pillarization process followed by Fe(III ion exchange. Kinetic study on MB degradation was conducted and evaluated by three kinetic models: the pseudo-first- and second-order equations and the Elovich equation. From the results, it is concluded that the degradation under the photo-Fenton-like process utilizing Fe(III/TiO2-montmorillonite photocatalyst conformed to the Elovich kinetic model.

Reliability modeling of an engineered barrier system

International Nuclear Information System (INIS)

Ananda, M.M.A.; Singh, A.K.; Flueck, J.A.

1993-01-01

The Weibull distribution is widely used in reliability literature as a distribution of time to failure, as it allows for both increasing failure rate (IFR) and decreasing failure rate (DFR) models. It has also been used to develop models for an engineered barrier system (EBS), which is known to be one of the key components in a deep geological repository for high level radioactive waste (HLW). The EBS failure time can more realistically be modelled by an IFR distribution, since the failure rate for the EBS is not expected to decrease with time. In this paper, we use an IFR distribution to develop a reliability model for the EBS

Reliability modeling of an engineered barrier system

International Nuclear Information System (INIS)

Ananda, M.M.A.; Singh, A.K.; Flueck, J.A.

1993-01-01

The Weibull distribution is widely used in reliability literature as a distribution of time to failure, as it allows for both increasing failure rate (IFR) and decreasing failure rate (DFR) models. It has also been used to develop models for an engineered barrier system (EBS), which is known to be one of the key components in a deep geological repository for high level radioactive waste (HLW). The EBS failure time can more realistically be modelled by an IFR distribution, since the failure rate for the EBS is not expected to decrease with time. In this paper, an IFR distribution is used to develop a reliability model for the EBS

Engineered sorbent barriers for low-level waste disposal

International Nuclear Information System (INIS)

Mitchell, S.J.; Freeman, H.D.; Buelt, J.L.

1986-01-01

Pacific Northwest Laboratory is developing sorbent materials to prevent the migration of radionuclides from low-level waste sites. These materials would allow water to pass, preventing the bathtub effect at humid sites. Screening studies identified promising sorbent materials for three key radionuclides: for cesium, greensand; for cobalt, activated charcoal; and for strontium, synthetic zeolite or clinoptilolite. Mixtures of these sorbent materials were tested in 0.6-m-diameter columns using radioactive leachates. To simulate expected worst-case conditions, the leachate solution contained the radionuclides, competing cations, and a chelating agent, adjusted to a pH of 5. A sorbent barrier comprised of greensand (1 wt %), activated charcoal (6 wt %), synthetic zeolite (20 wt %), and soil (73 wt %) achieved the decontamination factors necessary to meet the regulatory performance requirements established for this study. Sorbent barriers can be applied to shallow land burial, as backfill around the waste or engineered structures, or as backup to other liner systems. 2 refs., 6 figs., 3 tabs

Design of engineered sorbent barriers

International Nuclear Information System (INIS)

Jones, E.O.; Freeman, H.D.

1988-08-01

A sorbent barrier uses sorbent material such as activated carbon or natural zeolites to prevent the migration of radionuclides from a low-level waste site to the aquifer. The sorbent barrier retards the movement of radioactive contaminants, thereby providing time for the radionuclides to decay. Sorbent barriers can be a simple, effective, and inexpensive method for reducing the migration of radionuclides to the environment. Designing a sorbent barrier consists of using soil and sorbent material properties and site conditions as input to a model which will determine the necessary sorbent barrier thickness to meet contaminant limits. The paper will cover the following areas: techniques for measuring sorption properties of barrier materials and underlying soils, use of a radionuclide transport model to determine the required barrier thickness and performance under a variety of site conditions, and cost estimates for applying the barrier. 8 refs., 6 figs., 1 tab

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.

The effect of exchangeable cations in clinoptilolite and montmorillonite on the adsorption of aflatoxin B1

Directory of Open Access Journals (Sweden)

DRAGAN STOJSIC

2001-08-01

Full Text Available The adsorption of aflatoxin B1 (AFB1 by cation-exchanged clinoptilolite zeolitic tuff and montmorillonite was investigated at 37°C and pH 3.8 from an aqueous electrolyte having a composition similar to that of gastric juices of animals. Both minerals were exchanged from the natural form to the sodium form and then to the Cu2+, Zn2+ and Co2+-rich forms. The cation exchange was different for the different cations, but in all cases the exchanges were larger on montmorillonite than on clinoptilolite. The degree of exchange on montmorillonite was 76 % for copper (from a total of CEC 0.95 meq/g, Cu2+ –0.73 meq/g and 85 % for zinc and cobalt. Under the same conditions (concentration, temperature, pH, contact time, the degree of exchange on zeolitic tuff was 12 % for Cu2+ (from a total CEC of 1.46 meq/g, Cu2+ –0.17 meq/g, 8 % for Zn2+ and 10 % for Co2+. Both groups of mineral adsorbents showed high AFB1 chemisorption indexes (ca. For the montmorillonite forms, ca ranged from 0.75 for the Cu-exchanged montmorillonite to 0.89 for the natural Ca-form, 0.90 for the Zn-exchanged form and 0.93 for the Co-exchanged montmorillonite. The adsorption of AFB1 on the different exchanged forms of clinoptilolite gave similar values of ca for the Cu and Ca forms (0.90 and values of 0.94 and 0.95 for the Zn- and Co-exchanged form. The impact of the mineral adsorbents on the reduction of essential nutrients present in animal feed (Cu, Zn, Mn and Co showed that the Ca-rich montmorillonite had a higher capability for the reduction of the microelements than the Ca-rich clinoptilolite.

Possibility of ion-exchange column studies using stabilised montmorillonite-H aggregates; Possibilite d'etude d'echanges d'ions en colonne sur des agregats de Montmorillonite-H stabilises

Energy Technology Data Exchange (ETDEWEB)

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

1959-07-01

The conditions necessary for obtaining stable aggregates of montmorillonite-H, prepared without addition of organic flocculant, is discussed. These aggregates possess the same general ion-exchange properties as montmorillonite-H suspensions, about which many papers have been written. Their insolubility and their stable physical form enable them to be used in columns in exactly the same way as the usual organic ion exchangers. The examples of cation fixation and separation described in this report emphasize the similarities between the properties of this exchanger and those of organic cation-exchange resins, and open up possibilities for the extrapolation of the many investigations carried out on organic exchangers to mineral exchangers of this type. Amongst the essential differences to be remarked, we have shown that the properties of physical stability and chemical exchange remain the same at temperatures up to 300 deg. C, to a first approximation, under very intense {gamma} irradiation. (author) [French] Les conditions d'obtention d'agregats stables de montmorillonite-H prepares sans addition de floculant organique sont discutees. Ces agregats possedent les proprietes generales d'echangeurs d'ions des suspensions de montmorillonite-H, tres etudiees par de nombreux auteurs. Ils presentent une insolubilite et une forme physique stable permettant une utilisation en colonne identique a celle des echangeurs d'ions organiques usuels. Les exemples de fixation et de separation de cations qui ont ete decrits dans cet expose font ressortir les analogies entre les proprietes de cet echangeur et celles des resines organiques echangeurs de cations et permettent d'esperer une extrapolation aux echangeurs mineraux de ce type des tres nombreux travaux consacres aux echangeurs organiques. Parmi les differences essentielles a noter, nous avons mis en evidence que les proprietes de stabilite physique et d'echanges chimiques des agregats de montmorillonite subsistent a des

Using a systems engineering process to develop engineered barrier system design concepts

International Nuclear Information System (INIS)

Jardine, L.J.; Short, D.W.

1991-05-01

The methodology used to develop conceptual designs of the engineered barrier system and waste packages for a geologic repository is based on an iterative systems engineering process. The process establishes a set of general mission requirements and then conducts detailed requirements analyses using functional analyses, system concept syntheses, and trade studies identifications to develop preliminary system concept descriptions. The feasible concept descriptions are ranked based on selection factors and criteria and a set of preferred concept descriptions is then selected for further development. For each of the selected concept descriptions, a specific set of requirements, including constraints, is written to provide design guidance for the next and more detailed phase of design. The process documents all relevant waste management system requirements so that the basis and source for the specific design requirements are traceable and clearly established. Successive iterations performed during design development help to insure that workable concepts are generated to satisfy the requirements. 4 refs., 2 figs

Reactive barriers for 137Cs retention

International Nuclear Information System (INIS)

Krumhansl, James L.; Brady, Patrick V.; Anderson, Howard L.

2000-01-01

137 Cs was dispersed globally by cold war activities and, more recently, by the Chernobyl accident. Engineered extraction of 137 Cs from soils and groundwaters is exceedingly difficult. Because the half life of 137 Cs is only 30.2 years, remediation might be more effective (and less costly) if 137 Cs bioavailability could be demonstrably limited for even a few decades by use of a reactive barrier. Essentially permanent isolation must be demonstrated in those few settings where high nuclear level wastes contaminated the environment with 135 Cs (half life 2.3x10 6 years) in addition to 137 Cs. Clays are potentially a low-cost barrier to Cs movement, though their long-term effectiveness remains untested. To identify optimal clays for Cs retention Cs resorption was measured for five common clays: Wyoming Montmorillonite (SWy-1), Georgia Kaolinites (KGa-1 and KGa-2), Fithian Illite (F-Ill), and K-Metabentonite (K-Mbt). Exchange sites were pre-saturated with 0.16 M CsCl for 14 days and readily exchangeable Cs was removed by a series of LiNO 3 and LiCl washes. Washed clay were then placed into dialysis bags and the Cs release to the deionized water outside the bags measured. Release rates from 75 to 139 days for SWy-1, K-Mbt and F- 111 were similar; 0.017 to 0.021% sorbed Cs released per day. Both kaolinites released Cs more rapidly (0.12 to 0.05% of the sorbed Cs per day). In a second set of experiments, clays were doped for 110 days and subjected to an extreme and prolonged rinsing process. All the clays exhibited some capacity for irreversible Cs uptake so most soils have some limited ability to act as a natural barrier to Cs migration. However, the residual loading was greatest on K-Mbt (∼ 0.33 wt% Cs). Thus, this clay would be the optimal material for constructing artificial reactive barriers

Scientific investigation plan for initial engineered barrier system field tests

International Nuclear Information System (INIS)

Wunan Lin.

1993-02-01

The purpose of this Scientific Investigation Plan (SIP) is to describe tests known as Initial Engineered Barrier System Field Tests (IEBSFT) and identified by Work Breakdown Structure as WBS 1.2.2.2.4. The IEBSFT are precursors to the Engineered Barrier System Field Test (EBSFT), WBS 1.2.2.2.4, to be conducted in the Exploratory Study Facility (ESF) at Yucca Mountain. The EBSFT and IEBSFT are designed to provide information on the interaction between waste packages (simulated by heated containers) and the surrounding rock mass, its vadose water, and infiltrated water. Heater assemblies will be installed in drifts or boreholes openings and heated to measure moisture movement during heat-up and subsequent cool-down of the rock mass. In some of the tests, infiltration of water into the heated rock mass will be studied. Throughout the heating and cooling cycle, instruments installed in the rock will monitor such parameters as temperature, moisture content, concentration of some chemical species, and stress and strain. Rock permeability measurements, rock and fluid (water and gas) sampling, and fracture pattern measurements will also be made before and after the test

Assessment on mechanical effect of engineering barrier system to fault movement. Research document

International Nuclear Information System (INIS)

Hirai, Takashi; Tanai, Kenji; Takaji, Kazuhiko; Ohnuma, Satoshi

2003-03-01

The objective of this report is to clarify mechanical effect of engineering barrier system to the unavoidable fault movement. From the basic policy of the second progress report by JNC, natural phenomenon which affect strongly to the geological disposal system should be avoided. However, small faults as sliprate ''C'' far from principal fault zone, are difficult to be found out completely. Therefore, it is important to evaluate the influence of these fault movements and to clarify stability and safety of the engineered barrier system. Accordingly, the effect of a rock displacement across a deposition holl was considered and the midium scale test was carried out. Then midium scale test was simulated by Finit Element Method in which the constitutive model of Tresca was adopted to analyze elastoplastic behavior of buffer material. From the result of the midium scale test and the analysis, it was realized that the buffer material diminish shear stress acting on the overpack. Further analytical study was conducted to evaluate the real scale engineered barrier system designed in the second progress report by JNC. From the study, it was appeared that stress in buffer corresponded to the stress calculated for the midium scale test model. Consequently, it was obvious that rock displacement, 80% of buffer didn't affect overpack if velocity of fault movement was under 10 cm/sec. (author)

Carbon nanotubes rooted montmorillonite (CNT-MM) reinforced nanocomposite membrane for PEM fuel cells

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); Avila, Ricardo E. [Personal Dosimetry Section, Chilean Nuclear Energy Commission, Cas. 188-D, Santiago (Chile); Siddheswaran, Rajendran [Department of Materials Engineering, Faculty of Engineering, University of Concepcion, Concepcion (Chile); Ananthakumar, Solaiappan [Materials and Minerals Division, National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum, Kerala (India)

2012-05-15

Highlights: Black-Right-Pointing-Pointer Novel montmorillonite-CNT (MM-CNT) nanohybrid materials were produced by CVD. Black-Right-Pointing-Pointer Highly selective crystalline carbon nanotubes were grown over montmorillonite. Black-Right-Pointing-Pointer Fabricated Nafion-MM-CNT nanocomposite membrane by solution casting method. Black-Right-Pointing-Pointer Homogeneous dispersion of MM-CNT in the Nafion matrix was achieved. Black-Right-Pointing-Pointer Combined effect of montmorillonite and CNT improves the thermal stability of Nafion. - Abstract: Nafion based nanocomposite membranes containing montmorillonite-carbon nanotubes (a binary hybrid material) were produced to develop high performance polymer electrolyte fuel cells. Multi walled carbon nanotubes were grown over 20 and 25 wt% iron loaded montmorillonite catalysts by CVD using acetylene as the carbon precursor. Growth experiments were carried out at optimised conditions to obtain highly selective crystalline carbon nanotubes. X-ray diffraction spectra of the catalysts were recorded for the structural characterisation and definition of particle size. The carbon nanotubes obtained were examined by various physico chemical characterisation studies such as SEM, TEM, Raman spectroscopy and TG analyses to understand the morphology and crystallinity of the CNTs. The MM-CNT hybrid material with I{sub D}/I{sub G} ratio of Raman spectral band as 0.53 represents the high selectivity towards CNTs. Thus the hybrid material produced was considered as the best nanofiller to develop polymer nanocomposites. Nafion based nanocomposite membranes were prepared by adding MM-CNT as nanofiller by solution casting method. A better dispersion of MM-CNT into the Nafion matrix was observed and the addition of the MM-CNT improved the thermal stability of the Nafion membrane.

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.

Physico-mechanical properties of silanized-montmorillonite reinforced chitosan-co-poly(maleic anhydride) composites

Science.gov (United States)

Saputra, O. A.; Fajrin, A.; Nauqinida, M.; Suryanti, V.; Pramono, E.

2017-07-01

To solve the problems of dependence on petroleum as starting material in the manufacturing of plastics in Indonesia, green plastic from biopolymer like chitosan to be one of promising options and alternative to replace the conventional plastics. However, to overcome the mechanical and physical properties of chitosan, the addition of reinforcement agent was introduced. In this study, silanized-montmorillonite (sMMt) has been prepared as a reinforcement agent in the chitosan-co-poly(maleic anhydride) (referred as Cs-MAH) matrix. Silanizing of montmorillonite is one of strategy to improve the interaction between montmorillonite and chitosan, consequently, the mechanical properties, tensile strength of composites contained 6 phr of sMMt improved 56.5% to chitosan. Moreover, the presence both MAH and sMMt on the comosites also reduced swelling degree and swelling area by 20.6% and 26.7%.

International Collaboration Activities on Engineered Barrier Systems

Energy Technology Data Exchange (ETDEWEB)

Jove-Colon, Carlos F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-08-31

The Used Fuel Disposition Campaign (UFDC) within the DOE Fuel Cycle Technologies (FCT) program has been engaging in international collaborations between repository R&D programs for high-level waste (HLW) disposal to leverage on gathered knowledge and laboratory/field data of near- and far-field processes from experiments at underground research laboratories (URL). Heater test experiments at URLs provide a unique opportunity to mimetically study the thermal effects of heat-generating nuclear waste in subsurface repository environments. Various configurations of these experiments have been carried out at various URLs according to the disposal design concepts of the hosting country repository program. The FEBEX (Full-scale Engineered Barrier Experiment in Crystalline Host Rock) project is a large-scale heater test experiment originated by the Spanish radioactive waste management agency (Empresa Nacional de Residuos Radiactivos S.A. – ENRESA) at the Grimsel Test Site (GTS) URL in Switzerland. The project was subsequently managed by CIEMAT. FEBEX-DP is a concerted effort of various international partners working on the evaluation of sensor data and characterization of samples obtained during the course of this field test and subsequent dismantling. The main purpose of these field-scale experiments is to evaluate feasibility for creation of an engineered barrier system (EBS) with a horizontal configuration according to the Spanish concept of deep geological disposal of high-level radioactive waste in crystalline rock. Another key aspect of this project is to improve the knowledge of coupled processes such as thermal-hydro-mechanical (THM) and thermal-hydro-chemical (THC) operating in the near-field environment. The focus of these is on model development and validation of predictions through model implementation in computational tools to simulate coupled THM and THC processes.

Characterization of sodium dodecyl sulfate modified iron pillared montmorillonite and its application for the removal of aqueous Cu(II) and Co(II)

International Nuclear Information System (INIS)

Li Shuzhen; Wu Pingxiao

2010-01-01

Anionic surfactant modified Fe-pillared montmorillonites were prepared by Fe-hydrate solution and sodium dodecyl sulfate (SDS) solution. These organo-inorgano complex montmorillonites were divided into three types (CM1, CM2 and CM3) depending on different intercalation processes. X-ray diffraction spectra, the Fourier transform infrared (FTIR) spectra were used to analyze the structure of the raw and modified montmorillonites. X-ray photoelectron spectra of the simples have been studied to determine spectral characteristics to allow the identification of Fe(III) hydroxide. The specific surface area of the host montmorillonite (M0) is 73.2 m 2 /g, while for the modified montmorillonites it is 114.0 m 2 /g, 117.2 m 2 /g, and 115.8 m 2 /g, respectively. The mesopore volumes of the montmorillonites decrease after modification. Ions of copper and cobalt were selected as adsorbates to evaluate the adsorption performance of each montmorillonite. The adsorption data was analyzed by both Freundlich and Langmuir isotherm models and the data was well fit by the Langmuir isotherm model. The adsorption was efficient and significantly influenced by metal speciation, metal concentration, contact time, and pH. Higher adsorption capacity of the modified montmorillonites were obtained at pH 5-6. The results of desorption indicated that the metal ions were covalently bound to the modified montmorillonites.

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)

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

Performance of high level waste forms and engineered barriers under repository conditions

International Nuclear Information System (INIS)

1991-02-01

The IAEA initiated in 1977 a co-ordinated research programme on the ''Evaluation of Solidified High-Level Waste Forms'' which was terminated in 1983. As there was a continuing need for international collaboration in research on solidified high-level waste form and spent fuel, the IAEA initiated a new programme in 1984. The new programme, besides including spent fuel and SYNROC, also placed greater emphasis on the effect of the engineered barriers of future repositories on the properties of the waste form. These engineered barriers included containers, overpacks, buffer and backfill materials etc. as components of the ''near-field'' of the repository. The Co-ordinated Research Programme on the Performance of High-Level Waste Forms and Engineered Barriers Under Repository Conditions had the objectives of promoting the exchange of information on the experience gained by different Member States in experimental performance data and technical model evaluation of solidified high level waste forms, components of the waste package and the complete waste management system under conditions relevant to final repository disposal. The programme includes studies on both irradiated spent fuel and glass and ceramic forms as the final solidified waste forms. The following topics were discussed: Leaching of vitrified high-level wastes, modelling of glass behaviour in clay, salt and granite repositories, environmental impacts of radionuclide release, synroc use for high--level waste solidification, leachate-rock interactions, spent fuel disposal in deep geologic repositories and radionuclide release mechanisms from various fuel types, radiolysis and selective leaching correlated with matrix alteration. Refs, figs and tabs

Highly anisotropic conductivity of tablets pressed from polyaniline-montmorillonite nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Tokarský, Jonáš, E-mail: jonas.tokarsky@vsb.cz [Nanotechnology centre, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); IT4Innovations Centre of Excellence, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); Kulhánková, Lenka [Faculty of Metallurgy and Materials Engineering, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); Neuwirthová, Lucie; Mamulová Kutláková, Kateřina [Nanotechnology centre, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); Vallová, Silvie [Faculty of Metallurgy and Materials Engineering, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); Stýskala, Vítězslav [Faculty of Electrical Engineering and Computer Science, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); Čapková, Pavla [Faculty of Science, University of J.E. Purkyně, České mládeže 8, 400 96 Ústí nad Labem (Czech Republic)

2016-03-15

Highlights: • Montmorillonite (MMT) can be intercalated with polyaniline (PANI) chains. • Tablets pressed from PANI/MMT exhibit high anisotropy in electrical conductivity. • Pressure 28MPa is sufficient to reach the anisotropy. • Tablets pressed from pure PANI also exhibit anisotropy in electrical conductivity. - Abstract: Polyaniline-montmorillonite nanocomposite was prepared from anilinium sulfate (precursor) and ammonium peroxodisulfate (oxidizing agent) using simple one-step method. The resulting nanocomposite obtained in powder form has been pressed into tablets using various compression pressures (28–400 MPa). Electrical conductivities of tablets in two perpendicular directions, i.e. direction parallel with the main surface of tablet (σ=) and in orthogonal direction (σ⊥), and corresponding anisotropy factors (i.e., the ratio σ=/σ⊥) have been studied in dependence on compression pressure used during the preparation. Polyaniline-montmorillonite nanocomposite was characterized using X-ray diffraction analysis, raman spectroscopy, transmission electron microscopy, thermogravimetric analysis and molecular modeling which led to the understanding of the internal structure. Measurement of hardness performed on pressed tablets has been also involved. Taking into account the highest value of anisotropy factor reached (σ=/σ⊥ = 490), present study shows a chance to design conductors with nearly two-dimensional conductivity.

Highly anisotropic conductivity of tablets pressed from polyaniline-montmorillonite nanocomposite

International Nuclear Information System (INIS)

Tokarský, Jonáš; Kulhánková, Lenka; Neuwirthová, Lucie; Mamulová Kutláková, Kateřina; Vallová, Silvie; Stýskala, Vítězslav; Čapková, Pavla

2016-01-01

Highlights: • Montmorillonite (MMT) can be intercalated with polyaniline (PANI) chains. • Tablets pressed from PANI/MMT exhibit high anisotropy in electrical conductivity. • Pressure 28MPa is sufficient to reach the anisotropy. • Tablets pressed from pure PANI also exhibit anisotropy in electrical conductivity. - Abstract: Polyaniline-montmorillonite nanocomposite was prepared from anilinium sulfate (precursor) and ammonium peroxodisulfate (oxidizing agent) using simple one-step method. The resulting nanocomposite obtained in powder form has been pressed into tablets using various compression pressures (28–400 MPa). Electrical conductivities of tablets in two perpendicular directions, i.e. direction parallel with the main surface of tablet (σ=) and in orthogonal direction (σ⊥), and corresponding anisotropy factors (i.e., the ratio σ=/σ⊥) have been studied in dependence on compression pressure used during the preparation. Polyaniline-montmorillonite nanocomposite was characterized using X-ray diffraction analysis, raman spectroscopy, transmission electron microscopy, thermogravimetric analysis and molecular modeling which led to the understanding of the internal structure. Measurement of hardness performed on pressed tablets has been also involved. Taking into account the highest value of anisotropy factor reached (σ=/σ⊥ = 490), present study shows a chance to design conductors with nearly two-dimensional conductivity.

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)

Durability of Dukovany shallow land repository engineered barriers. Appendix 7: Czech Republic

International Nuclear Information System (INIS)

Vokal, A.; Nachmilner, L.; Wasserbauer, R.; Dohnalek, J.

2001-01-01

The main aim of this project was to explore the durability of engineering barriers used at Dukovany shallow land repository as a support of safety assessments. This appendix summarises the principal results focused on durability of asphaltopropyleneconcrete (APC) hydroisolation and steel reinforced concrete construction

Design studies on the engineered barrier system and on the in-situ experiments under the conditions of geological environment in Horonobe

International Nuclear Information System (INIS)

Kurihara, Yuji; Yui, Mikazu; Tanai, Kenji

2004-04-01

Following studies have been done in this papers in order to apply the technologies based on H12 report to the actual geological conditions of Horonobe underground research laboratory. 1) Reconsidering the process of repository design, the design process charts of a repository were presented. In the H12 report, the design process of the engineering barrier system was followed by the facility design process. In this paper, the both processes were placed in parallel position. 2) The relation between geological conditions and the performance of engineering barrier systems and the specifications of engineering barrier systems was arranged and the geological information needed for design of engineering barrier were selected. 3) The appropriate form of geological information as input-data for design were showed and the procedure for setting input-data was presented. 4) Based on the state of geological investigations at Horonobe, mechanical input-data were arranged for the design of the in-situ experiments on engineered barrier system at HORONOBE. 5) The stability of the hall for the in-situ experiments was studied by numerical analysis and the results indicated that there are difference in stability between the depth of 500 m and 570 m. (author)

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

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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.

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.

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

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.

The application of modified montmorillonite in the processes of baromembrane purification of water from U (VI)

International Nuclear Information System (INIS)

Yurlova, L.Yu.; Krivoruchko, A.P.

2010-01-01

The processes of uranium-containing water purification by ultra- and nanofiltration methods combined with the use of montmorillonite modified by polyethyleneimine are studied. It is shown that the application of montmorillonite allows one to obtain the high indices of the uranium-containing water purification by baromembrane methods.

Synthesis and Characterization of CdS/TiO2-Montmorillonite Nanocomposite with Enhanced Visible-Light Absorption

Directory of Open Access Journals (Sweden)

Feng-shan Zhou

2014-01-01

Full Text Available Sodium montmorillonite (MMT was chosen as the carrier; a serial of CdS/TiO2-MMT nanocomposites with enhanced visible-light absorption ability was prepared by hydrothermal synthesis method combination with semiconductor compound modification method. The samples are characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and ultraviolet visible (UV-Vis spectroscopy; the results showed that TiO2 and CdS nanoparticles were loaded on the surface of montmorillonite uniformly. N2 adsorption-desorption experiment showed that the specific surface area of TiO2/montmorillonite nanocomposite made by this method can reach 200 m2/g and pore-size distribution was from 4 to 6 nm; UV-Vis showed that the recombination of CdS and TiO2 enhanced visible-light absorption ability of samples of TiO2/montmorillonite and visible-light absorption ability increase with the increased of the adsorption of CdS.

Nanocomposites of rice and banana flours blend with montmorillonite: partial characterization.

Science.gov (United States)

Rodríguez-Marín, María L; Bello-Pérez, Luis A; Yee-Madeira, Hernani; Zhong, Qixin; González-Soto, Rosalía A

2013-10-01

Rice and banana flours are inexpensive starchy materials that can form films with more improved properties than those made with their starch because flour and starch present different hydrophobicity. Montmorillonite (MMT) can be used to further improve the properties of starch-based films, which has not received much research attention for starchy flours. The aim of this work was to evaluate the mechanical and barrier properties of nanocomposite films of banana and rice flours as matrix material with addition of MMT as a nanofiller. MMT was modified using citric acid to produce intercalated structures, as verified by the X-ray diffraction pattern. The intercalated MMT was blended with flour slurries, and films were prepared by casting. Nanocomposite films of banana and rice flours presented an increase in the tensile at break and elongation percentage, respectively, more than their respective control films without MMT. This study showed that banana and rice flours could be alternative raw materials to use in making nanocomposite films. Copyright © 2013 Elsevier B.V. All rights reserved.

Investigation of the long term stability and corrosion resistance of engineering barriers

International Nuclear Information System (INIS)

Aoyama, Eri; Tachikawa, Hirokazu; Shimizu, Akihiko

2005-03-01

The Japan Nuclear Cycle Development Institute submitted 'Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan' to the Japanese government. This report contains investigations of the long term behavior of alteration of bentonite, and of the corrosion life time of overpack on the basis of experimental data and past research, assuming the ranging geological environment of Japan. However some subjects, such as the behavior of the bentonite and overpack under high pH conditions and the behavior of the engineering barrier with change of near-field environmental condition with time for promoting reliability have still been left. To take into account these conditions, expert committees composed of clay science and metal corrosion science experts were established in the Nuclear Safety Research Association and past research outcomes and the theory of safety assessment were investigated from the view points of long term stability and corrosion resistance of engineering barrier. (author)

NASA GSFC Science Communication Working Group: Addressing Barriers to Scientist and Engineer Participation in Education and Public Outreach Activities

Science.gov (United States)

Bleacher, L.; Hsu, B. C.; Campbell, B. A.; Hess, M.

2011-12-01

The Science Communication Working Group (SCWG) at NASA Goddard Space Flight Center (GSFC) has been in existence since late 2007. The SCWG is comprised of education and public outreach (E/PO) professionals, public affairs specialists, scientists, and engineers. The goals of the SCWG are to identify barriers to scientist and engineer engagement in E/PO activities and to enable those scientists and engineers who wish to contribute to E/PO to be able to do so. SCWG members have held meetings with scientists and engineers across GSFC to determine barriers to their involvement in E/PO. During these meetings, SCWG members presented examples of successful, ongoing E/PO projects, encouraged active research scientists and engineers to talk about their own E/PO efforts and what worked for them, discussed the E/PO working environment, discussed opportunities for getting involved in E/PO (particularly in high-impact efforts that do not take much time), handed out booklets on effective E/PO, and asked scientists and engineers what they need to engage in E/PO. The identified barriers were consistent among scientists in GSFC's four science divisions (Earth science, planetary science, heliophysics, and astrophysics). Common barriers included 1) lack of time, 2) lack of funding support, 3) lack of value placed on doing E/PO by supervisors, 4) lack of training on doing appropriate/effective E/PO for different audiences, 5) lack of awareness and information about opportunities, 6) lack of understanding of what E/PO really is, and 7) level of effort required to do E/PO. Engineers reported similar issues, but the issues of time and funding support were more pronounced due to their highly structured work day and environment. Since the barriers were identified, the SCWG has taken a number of steps to address and rectify them. Steps have included holding various events to introduce scientists and engineers to E/PO staff and opportunities including an E/PO Open House, brown bag seminars on

Backfill barriers: the use of engineered barriers based on geologic materials to assure isolation of radioactive wastes in a repository. [Nickel-iron alloys

Energy Technology Data Exchange (ETDEWEB)

Apps, J.A.; Cook, N.G.W.

1981-06-01

A preliminary assessment is made to show that canisters fabricated of nickel-iron alloys, and surrounded by a suitable backfill, may produce an engineered barrier where the canister material is thermodynamically stable with respect to its environment. As similar conditions exist in nature, the performance of such systems as barriers to isolate radionuclides can be predicted over very long periods, of the order of 10/sup 6/ years.

Fabrication of High Gas Barrier Epoxy Nanocomposites: An Approach Based on Layered Silicate Functionalized by a Compatible and Reactive Modifier of Epoxy-Diamine Adduct

Directory of Open Access Journals (Sweden)

Ran Wei

2018-05-01

Full Text Available To solve the drawbacks of poor dispersion and weak interface in gas barrier nanocomposites, a novel epoxy-diamine adduct (DDA was synthesized by reacting epoxy monomer DGEBA with curing agent D400 to functionalize montmorillonite (MMT, which could provide complete compatibility and reactivity with a DGEBA/D400 epoxy matrix. Thereafter, sodium type montmorillonite (Na-MMT and organic-MMTs functionalized by DDA and polyether amines were incorporated with epoxy to manufacture nanocomposites. The effects of MMT functionalization on the morphology and gas barrier property of nanocomposites were evaluated. The results showed that DDA was successfully synthesized, terminating with epoxy and amine groups. By simulating the small-angle neutron scattering data with a sandwich structure model, the optimal dispersion/exfoliation of MMT was observed in a DDA-MMT/DGEBA nanocomposite with a mean radius of 751 Å, a layer thickness of 30.8 Å, and only two layers in each tactoid. Moreover, the DDA-MMT/DGEBA nanocomposite exhibited the best N2 barrier properties, which were about five times those of neat epoxy. Based on a modified Nielsen model, it was clarified that this excellent gas barrier property was due to the homogeneously dispersed lamellas with almost exfoliated structures. The improved morphology and barrier property confirmed the superiority of the adduct, which provides a general method for developing gas barrier nanocomposites.

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.

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.

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

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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.

Study on vibration behaviors of engineered barrier system

Energy Technology Data Exchange (ETDEWEB)

Mikoshiba, Tadashi; Ogawa, Nobuyuki; Minowa, Chikahiro [National Research Inst. for Earth Science and Disaster Prevention, Tsukuba, Ibaraki (Japan)

1999-02-01

Small engineered barrier model was mode and tested by vibrating with the random wave and the real earthquake wave. The wave observed at Kamaishi (N-S, N-W), Iwate Prefecture, in September 6, 1993, and Kobe (N-S) etc. were used as the real earthquake waves. The trial overpack showed non-linear characteristics (soft spring) by vibrating with the random wave. The pressure and acceleration of trial overpack and constraint container increased with increasing the vibration level of the real earthquake wave. The trial overpack moved the maximum 1.7 mm of displacement and 16 mm subsidence. The results showed both waves rocked the trialpack. (S.Y.)

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.

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

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

Construction and operational experiences of engineered barrier test facility for near surface disposal of LILW

International Nuclear Information System (INIS)

Park, Jin Beak; Park, Se Moon; Kim, Chang Lak

2003-01-01

Engineered barrier test facility is specially designed to demonstrate the performance of engineered barrier system for the near-surface disposal facility under the domestic environmental conditions. Comprehensive measurement systems are installed within each test cell. Long-and short-term monitoring of the multi-layered cover system can be implemented according to different rainfall scenarios with artificial rainfall system. Monitoring data on the water content, temperature, matric potential, lateral drainage and percolation of cover-layer system can be systematically managed by automatic data acquisition system. The periodic measurement data are collected and will be analyzed by a dedicated database management system, and provide a basis for performance verification of the disposal cover design

Solid-state synthesis and electrical properties of polyaniline/Cu-montmorillonite nanocomposite

International Nuclear Information System (INIS)

Bekri-Abbes, Imene; Srasra, Ezzeddine

2010-01-01

In this paper, the solid-state synthesis of polyaniline/Cu-montmorillonite nanocomposite is reported. Mixture of anilinium chlorure and Cu exchanged montmorillonite was grinded at room temperature while we vary the molar rate of aniline to interlayer Cu 2+ cations (R) from 0.5 to 6. The properties of the hybrid compounds are characterized by X-ray diffraction, thermogravimetric analysis, SEM, FTIR and impedance spectroscopy. The results showed that the structure and the conductivity of PANI in hybrid materials depend on R. The ac conduction showed a regime of constant dc conductivity at low frequencies and a crossover to a frequency-dependent regime of the type A ω s at high frequencies.

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.

Thermal barrier coatings: Coating methods, performance, and heat engine applications. (Latest citations from the EI Compendex*plus database). Published Search

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-02-01

The bibliography contains citations concerning conference proceedings on coating methods, performance evaluations, and applications of thermal barrier coatings as protective coatings for heat engine components against high temperature corrosions and chemical erosions. The developments of thermal barrier coating techniques for high performance and reliable gas turbines, diesel engines, jet engines, and internal combustion engines are presented. Topics include plasma sprayed coating methods, yttria stabilized zirconia coatings, coating life models, coating failure and durability, thermal shock and cycling, and acoustic emission analysis of coatings. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

Thermal barrier coatings: Coating methods, performance, and heat engine applications. (Latest citations from the EI Compendex*plus database). Published Search

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-11-01

The bibliography contains citations concerning conference proceedings on coating methods, performance evaluations, and applications of thermal barrier coatings as protective coatings for heat engine components against high temperature corrosions and chemical erosions. The developments of thermal barrier coating techniques for high performance and reliable gas turbines, diesel engines, jet engines, and internal combustion engines are presented. Topics include plasma sprayed coating methods, yttria stabilized zirconia coatings, coating life models, coating failure and durability, thermal shock and cycling, and acoustic emission analysis of coatings. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

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

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

Investigation of metallic, ceramic, and polymeric materials for engineered barrier applications in nuclear-waste packages

International Nuclear Information System (INIS)

Westerman, R.E.

1980-10-01

An effort to develop licensable engineered barrier systems for the long-term (about 1000 yr) containment of nuclear wastes under conditions of deep continental geologic disposal has been underway at Pacific Northwest Laboratory since January 1979, under the auspices of the High-Level Waste Immobilization Program. In the present work, the barrier system comprises the hard or structural elements of the package: the canister, the overpack(s), and the hole sleeve. A number of candidate metallic, ceramic, and polymeric materials were put through mechanical, corrosion, and leaching screening tests to determine their potential usefulness in barrier-system applications. Materials demonstrating adequate properties in the screening tests will be subjected to more detailed property tests, and, eventually, cost/benefit analyses, to determine their ultimate applicability to barrier-system design concepts. The following materials were investigated: two titanium alloys of Grade 2 and Grade 12; 300 and 400 series stainless steels, Inconels, Hastelloy C-276, titanium, Zircoloy, copper-nickel alloys and cast irons; total of 14 ceramic materials, including two grades of alumina, plus graphite and basalt; and polymers such as polyamide-imide, polyarylene, polyimide, polyolefin, polyphenylene sulfide, polysulfone, fluoropolymer, epoxy, furan, silicone, and ethylene-propylene terpolymer (EPDM) rubber. The most promising candidates for further study and potential use in engineered barrier systems were found to be rubber, filled polyphenylene sulfide, fluoropolymer, and furan derivatives

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)

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

Sorption of prioritized elements on montmorillonite colloids and their potential to transport radionuclides

International Nuclear Information System (INIS)

Wold, Susanna

2010-04-01

Due to colloids potential to bind radionuclides (RN) and even mobilise sorbed RN, colloid transport of RN should be taken into account when modeling radionuclide transport in the scenario of a leaking canister in a deep bedrock repository of spent nuclear fuel. Colloids are always present in natural waters and the concentrations are controlled by the groundwater chemistry where specifically the ionic strength is of major importance. In many deep bedrock groundwaters, the ionic strength is fairly high (above the Critical Coagulation Concentration) and therefore colloids are not likely to be stable. In these types of groundwaters colloid concentrations up to 100 μg/l could be expected, and clay colloids organic degradation products and bacteria and viruses represent can be found. In a long time perspective cycles of glaciations can be expected in Sweden as in other Nordic countries. It can not be excluded that glacial melt water can intrude to repository depth with high flows. In this scenario the groundwater conditions may drastically change. In contact with dilute groundwater the bentonite barrier can start to propagate a bentonite gel and further release montmorillonite colloids into water bearing fractures. The concentration of colloids in vicinity of the bentonite barrier can then increase drastically. In contact with Grimsel groundwater types with [Na] and [Ca] of 0.001 and 0.0001 M respectively a montmorillonite concentration of a maximum of 20 mg/l is expected. Further, the groundwater chemistry of Grimsel seems to be representative for glacial meltwater when comparing with the water chemistry data on meltwaters from existing glaciers. A key to be able to model colloid transport of radionuclides is the sorption strength and the sorption reversibility. To facilitate this, a compilation of literature K d -values and an inventory of available sorption kinetic data has been composed for the prioritized elements Pu, Th, Am, Pb, Pa, Ra, Np, Cm, Ac, Tc, Cs, Nb, Ni

Sorption of prioritized elements on montmorillonite colloids and their potential to transport radionuclides

Energy Technology Data Exchange (ETDEWEB)

Wold, Susanna (Royal Inst. of Technology, Stockholm (Sweden). School of Chemical Science and Engineering, Nuclear Chemistry)

2010-04-15

Due to colloids potential to bind radionuclides (RN) and even mobilise sorbed RN, colloid transport of RN should be taken into account when modeling radionuclide transport in the scenario of a leaking canister in a deep bedrock repository of spent nuclear fuel. Colloids are always present in natural waters and the concentrations are controlled by the groundwater chemistry where specifically the ionic strength is of major importance. In many deep bedrock groundwaters, the ionic strength is fairly high (above the Critical Coagulation Concentration) and therefore colloids are not likely to be stable. In these types of groundwaters colloid concentrations up to 100 mug/l could be expected, and clay colloids organic degradation products and bacteria and viruses represent can be found. In a long time perspective cycles of glaciations can be expected in Sweden as in other Nordic countries. It can not be excluded that glacial melt water can intrude to repository depth with high flows. In this scenario the groundwater conditions may drastically change. In contact with dilute groundwater the bentonite barrier can start to propagate a bentonite gel and further release montmorillonite colloids into water bearing fractures. The concentration of colloids in vicinity of the bentonite barrier can then increase drastically. In contact with Grimsel groundwater types with [Na] and [Ca] of 0.001 and 0.0001 M respectively a montmorillonite concentration of a maximum of 20 mg/l is expected. Further, the groundwater chemistry of Grimsel seems to be representative for glacial meltwater when comparing with the water chemistry data on meltwaters from existing glaciers. A key to be able to model colloid transport of radionuclides is the sorption strength and the sorption reversibility. To facilitate this, a compilation of literature K{sub d}-values and an inventory of available sorption kinetic data has been composed for the prioritized elements Pu, Th, Am, Pb, Pa, Ra, Np, Cm, Ac, Tc, Cs, Nb

Thermal analysis of the effect of thick thermal barrier coatings on diesel engine performance

International Nuclear Information System (INIS)

Hoag, K.L.; Frisch, S.R.; Yonushonis, T.M.

1986-01-01

The reduction of heat rejection from the diesel engine combustion chamber has been the subject of a great deal of focus in recent years. In the pursuit of this goal, Cummins Engine Company has received a contract from the Department of Energy for the development of thick thermal barrier coatings for combustion chamber surfaces. This contract involves the analysis of the impact of coatings on diesel engine performance, bench test evaluation of various coating designs, and single cylinder engine tests. The efforts reported in this paper center on the analysis of the effects of coatings on engine performance and heat rejection. For this analysis the conventional water cooled engine was compared with an engine having limited oil cooling, and utilizing zirocnia coated cylinder had firedecks and piston crowns. The analysis showed little or no benefits of similarly coating the valves or cylinder liner

Examining E-Learning Barriers as Perceived by Faculty Members of Engineering Colleges in the Jordanian Universities

Science.gov (United States)

Al-Alawneh, Muhammad K.

2014-01-01

Employing computer's technology that includes e-learning system in the field of Engineering is a vital issue which needs to be discussed. Therefore, this study purposed to examine e-learning barriers as perceived by faculty members of engineering in three major universities in Jordan (Yarmouk University, Jordan University of Science and…

Integrated modelling of near field and engineered barrier system processes

International Nuclear Information System (INIS)

Lamont, A.; Gansemer, J.

1994-01-01

The Yucca Mountain Integrating Model (YMIM) is an integrated model of the Engineered barrier System has been developed to assist project managers at LLNL in identifying areas where research emphasis should be placed. The model was designed to be highly modular so that a model of an individual process could be easily modified or replaced without interfering with the models of other processes. The modules modelling container failure and the dissolution of nuclides include particularly detailed, temperature dependent models of their corresponding processes

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.

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

Highly Controlled Diffusion Drug Release from Ureasil-Poly(ethylene oxide)-Na+-Montmorillonite Hybrid Hydrogel Nanocomposites.

Science.gov (United States)

Jesus, Celso R N; Molina, Eduardo F; Pulcinelli, Sandra H; Santilli, Celso V

2018-06-06

In this work, we report the effects of incorporation of variable amounts (1-20 wt %) of sodium montmorillonite (MMT) into a siloxane-poly(ethylene oxide) hybrid hydrogel prepared by the sol-gel route. The aim was to control the nanostructural features of the nanocomposite, improve the release profile of the sodium diclofenac (SDCF) drug, and optimize the swelling behavior of the hydrophilic matrix. The nanoscopic characteristics of the siloxane-cross-linked poly(ethylene oxide) network, the semicrystallinity of the hybrid, and the intercalated or exfoliated structure of the clay were investigated by X-ray diffraction, small-angle X-ray scattering, and differential scanning calorimetry. The correlation between the nanoscopic features of nanocomposites containing different amounts of MMT and the swelling behavior revealed the key role of exfoliated silicate in controlling the water uptake by means of a flow barrier effect. The release of the drug from the nanocomposite displayed a stepped pattern kinetically controlled by the diffusion of SDCF molecules through the mass transport barrier created by the exfoliated silicate. The sustained SDCF release provided by the hybrid hydrogel nanocomposite could be useful for the prolonged treatment of painful conditions, such as arthritis, sprains and strains, gout, migraine, and pain after surgical procedures.

Barrier Properties and Structural Study of Nanocomposite of HDPE/Montmorillonite Modified with Polyvinylalcohol

Directory of Open Access Journals (Sweden)

María C. Carrera

2013-01-01

Full Text Available In this work was studied the permeation of CO2 in films of high-density polyethylene (HDPE and organoclay modified with polyvinylalcohol (MMTHDTMA/PVA obtained from melt blending. Permeation study showed that the incorporation of the modified organoclay generates a significant effect on the barrier properties of HDPE. When a load of 2 wt% of MMTHDTMA/PVA was incorporated in the polymer matrix, the flow of CO2 decreased 43.7% compared to pure polyethylene. The results of TEM showed that clay layers were dispersed in the polymeric matrix, obtaining an exfoliated-structure nanocomposite. The thermal stability of nanocomposite was significantly enhanced with respect to the pristine HDPE. DSC results showed that the crystallinity was maintained as the pure polymeric matrix. Consequently, the decrease of permeability was attributable only to the effect of tortuosity generated by the dispersion of MMTHDTMA/PVA. Notably the mechanical properties remain equal to those of pure polyethylene, but with an increase in barrier properties to CO2. This procedure allows obtaining nanocomposites of HDPE with a good barrier property to CO2 which would make it competitive in the use of packaging.

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)

FAILURE MECHANISMS OF THERMAL BARRIER COATINGS INTERNAL COMBUSTION ENGINES AND llMPROVEMENTS

Directory of Open Access Journals (Sweden)

ADNAN PARLAK

2003-04-01

Full Text Available MechanicaJ properties of high performance ceramics have been improved to the point where their use in heat engines is possible. The high temperature strength and low thermal expansion properties of bigh performance ceramics offer an advantage over metals in the development of non-water cooling engine. However, because bard environment in diesel engine combustion chamber, solving the problem of durabiUty of TBC is important. DurabiUty of thermal barrier coatings(TBC is liınited by two main failure mechanisms: Therınal expansion nlİsmatch betwcen bond coat and top coat and bond coat oxidation. Both of these can cause failure of the ceramic top coat. Developments of recent years sholv that bond coats \\Vith higher oxidation resistance tend to have better coating system cyclic lives

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.

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

Experimental Study on the Interaction Between Contacting Barrier Materials for Containment of Radioactive Wastes

Science.gov (United States)

Huang, W. H.; Chang, H. C.

2017-12-01

The disposal of low- and intermediate-level radioactive wastes requires use of multi-barriers for isolation of the wastes from the biosphere. Typically, the engineered barriers are composed of a concrete vault, buffer and backfill materials. Zhishin clay and Black Hill bentonite were used as raw clay material in making buffer and backfill materials in this study. These clays were compacted to make buffer material, or mixed with Taitung area argillite to produce backfill material for potential application as barriers for the disposal of low- and intermediate-level radioactive wastes. The interaction between concrete barrier and the buffer/backfill material is simulated by an accelerated migration test to investigate the effect of contacting concrete on the expected functions of buffer/backfill material. The results show buffer material close to the contact with concrete exhibits significant change in the ratio of calcium/sodium exchange capacity, due to the move of calcium ions released from the concrete. The shorter the distance from the contacting interface, the ratio of the calcium/sodium concentration in buffer/backfill materials increases. The longer the distance from the interface, the effect of the contact on alteration in clays become less significant. Also, some decreases in swelling capacity in the buffer/backfill material near the concrete-backfill interface are noted. Finally, a comparison is made between Zhisin clay and Balck Hill bentonite on the interaction between concrete and the two clays. Black Hill bentonite was found to be influenced more by the interaction, because of the higher content of montmorillonite. On the other hand, being a mixture of clay and sand, backfill material is less affected by the decalsification of concrete at the contact than buffer material.

Assessment of Environmental Factors of Geology on Waste and Engineering Barriers for Waste Storage Near Surface

International Nuclear Information System (INIS)

Arimuladi SP

2007-01-01

Geological environment factors include features and processes occurring within that spatial and temporal (post-closure) domain whose principal effect is to determine the evolution of the physical, chemical, biological and human conditions of the domain that are relevant to estimating the release and migration of radionuclide and consequent exposure to man. Hardness of radioactive waste and engineer barrier can be decrease by environmental factors. Disposal system domain geological environment factors is a category in the International FEP list and is divided into sub-categories. There are 13 sub-factors of geological environment, 12 sub-factors influence hardness of radioactive waste and engineer barrier, thermal processes and conditions in geosphere can be excluded. (author)

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

PILOT-SCALE EVALUATION OF ENGINEERED BARRIER SYSTEMS FOR THE YUCCA MOUNTAIN PROJECT

International Nuclear Information System (INIS)

Webb, S.W.; George, J.T.; Finley, R.E.

2001-01-01

This paper describes two quarter-scale experiments (1.4 m diameter) and associated numerical analyses on granular backfill engineered barrier systems in support of the Yucca Mountain Project for the potential repository. The two configurations include a sloped capillary barrier and a plain backfill. The tests involve application of dyed water as a constant line infiltration source along the top of the test set-up, monitoring water movement through the test, and measuring water exiting the experiments. A complete water balance estimate is made for each test, and observed water movement is compared with (1) detailed numerical analyses conducted using the TOUGH2 code for unsaturated flow in porous media and (2) posttest observations. The results of the testing and analyses show that for the injection rates and configuration applied, the capillary barrier design diverts a significant amount of all injected water and the TOUGH2 pretest predictions show qualitative and quantitative agreement with the experimental data

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture.

Science.gov (United States)

Karthikeya Sharma, T

2015-11-01

Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine's performance within the range studied.

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.

Characterization and Catalytic Activity of Montmorillonite K10-Supported Cobalt Catalysts

International Nuclear Information System (INIS)

Gobara, H.M.; Ghattas, M.S.; Henien, S.A.

2010-01-01

Montmorillonite K10-supported cobalt catalysts were prepared by wet impregnation method. The samples were analyzed by XRD, TPR, FTTR and BET characterization techniques. [Three phases of cobalt species were identified namely, cobalt oxide (Co 3 O 4 ), cobalt silicate (Co 2 S 1 O 4 ) and cobalt aluminate (CoAl 2 O 4 ). These species were most probably existing within the inter lamellar spaces of the meso porous montmorillonite K10 support]. The two bands observed at 1385 and 760 cm 1 were characteristic of metal species rather than the support, being mostly of Co - O bond vibration. The hysteresis loop, pore size distribution, pore volume and BET surface area were greatly affected by cobalt loading. The catalyst containing 18 wt% cobalt was the most selective sample for ethylene production from ethanol dehydration.

Engineered barrier development for a nuclear waste repository in basalt: an integration of current knowledge

Energy Technology Data Exchange (ETDEWEB)

Smith, M.J.

1980-05-01

This document represents a compilation of data and interpretive studies conducted as part of the engineered barriers program of the Basalt Waste Isolation Project. The overall objective of these studies is to provide information on barrier system designs, emplacement and isolation techniques, and chemical reactions expected in a nuclear waste repository located in the basalts underlying the Hanford Site within the state of Washington. Backfills, waste-basalt interactions, sorption, borehole plugging, etc., are among the topics discussed.

Engineered barrier development for a nuclear waste repository in basalt: an integration of current knowledge

International Nuclear Information System (INIS)

Smith, M.J.

1980-05-01

This document represents a compilation of data and interpretive studies conducted as part of the engineered barriers program of the Basalt Waste Isolation Project. The overall objective of these studies is to provide information on barrier system designs, emplacement and isolation techniques, and chemical reactions expected in a nuclear waste repository located in the basalts underlying the Hanford Site within the state of Washington. Backfills, waste-basalt interactions, sorption, borehole plugging, etc., are among the topics discussed

Employees' Perceptions of Barriers to Participation in Training and Development in Small Engineering Businesses

Science.gov (United States)

Susomrith, Pattanee; Coetzer, Alan

2015-01-01

Purpose: This paper aims to investigate barriers to employee participation in voluntary formal training and development opportunities from the perspective of employees in small engineering businesses. Design/methodology/approach: An exploratory qualitative methodology involving data collection via site visits and in-depth semi-structured…

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

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).

Experimental methodology to study radionuclide sorption and migration in geological formations and engineered barriers of waste repositories

International Nuclear Information System (INIS)

Rojo Sanz, H.

2010-01-01

In Spain, the waste management options include either the possibility of a final storage in a deep geological repository (DGR) or the centralized temporal surface disposal (CTS). DGRs are based in a multi-barrier concept with the geological barrier and including the vitrified waste, the metal containers and engineered barriers such as compacted bentonite and cement-based materials. On the other hand, CTS mainly considers concrete and cement to confine the metal canisters containing the waste. Radionuclide migration will mainly take place by the existence of chemical concentration gradients being thus diffusion the main transport mechanism or by the existence of hydraulic gradients due to the existence of water-conductive fractures. Radionuclide sorption/retention on the materials composing the natural and engineered barriers is the fundamental process controlling contaminant migration. The evaluation of sorption parameters and the understanding of the different mechanisms leading to radionuclide retention are very important issues. The study of diffusion processes is very relevant as well. This paper describes the main experimental methodologies applied to analyse radionuclide transport in the different barriers of radioactive repositories. Particularly we focused on obtaining of retention parameters as distribution coefficients, kd, or retardation factors, Rf, and diffusion coefficients of radionuclides. (Author) 6 refs.

Engineering an in vitro air-blood barrier by 3D bioprinting

Science.gov (United States)

Horváth, Lenke; Umehara, Yuki; Jud, Corinne; Blank, Fabian; Petri-Fink, Alke; Rothen-Rutishauser, Barbara

2015-01-01

Intensive efforts in recent years to develop and commercialize in vitro alternatives in the field of risk assessment have yielded new promising two- and three dimensional (3D) cell culture models. Nevertheless, a realistic 3D in vitro alveolar model is not available yet. Here we report on the biofabrication of the human air-blood tissue barrier analogue composed of an endothelial cell, basement membrane and epithelial cell layer by using a bioprinting technology. In contrary to the manual method, we demonstrate that this technique enables automatized and reproducible creation of thinner and more homogeneous cell layers, which is required for an optimal air-blood tissue barrier. This bioprinting platform will offer an excellent tool to engineer an advanced 3D lung model for high-throughput screening for safety assessment and drug efficacy testing. PMID:25609567

Choice of french clays as engineered barrier components for waste disposal

International Nuclear Information System (INIS)

Coulon, H.; Lajudie, A.; Debrabant, P.; Atabek, R.; Jorda, M.; Andre-Jehan, R.

1987-01-01

Results are presented of physical measurements on candidate buffer materials for use in nuclear fuel waste disposal. The materials being considered as constituent elements of engineered barriers are essentially calcium smectite clays, in other terms swelling clays, coming from fourteen french deposits. The criteria for good candidates are mainly: smectite content in the clay materials, carbonate and organic material content and bulk density of the material, compacted under a pressure of 100 MPa. 14 references, 4 figures, 6 tables

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

Bacterial Diversity in Bentonites, Engineered Barrier for Deep Geological Disposal of Radioactive Wastes.

Science.gov (United States)

Lopez-Fernandez, Margarita; Cherkouk, Andrea; Vilchez-Vargas, Ramiro; Jauregui, Ruy; Pieper, Dietmar; Boon, Nico; Sanchez-Castro, Ivan; Merroun, Mohamed L

2015-11-01

The long-term disposal of radioactive wastes in a deep geological repository is the accepted international solution for the treatment and management of these special residues. The microbial community of the selected host rocks and engineered barriers for the deep geological repository may affect the performance and the safety of the radioactive waste disposal. In this work, the bacterial population of bentonite formations of Almeria (Spain), selected as a reference material for bentonite-engineered barriers in the disposal of radioactive wastes, was studied. 16S ribosomal RNA (rRNA) gene-based approaches were used to study the bacterial community of the bentonite samples by traditional clone libraries and Illumina sequencing. Using both techniques, the bacterial diversity analysis revealed similar results, with phylotypes belonging to 14 different bacterial phyla: Acidobacteria, Actinobacteria, Armatimonadetes, Bacteroidetes, Chloroflexi, Cyanobacteria, Deinococcus-Thermus, Firmicutes, Gemmatimonadetes, Planctomycetes, Proteobacteria, Nitrospirae, Verrucomicrobia and an unknown phylum. The dominant groups of the community were represented by Proteobacteria and Bacteroidetes. A high diversity was found in three of the studied samples. However, two samples were less diverse and dominated by Betaproteobacteria.

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

Esterification of phenyl acetic acid with p-cresol using metal cation exchanged montmorillonite nanoclay catalysts.

Science.gov (United States)

Bhaskar, M; Surekha, M; Suma, N

2018-02-01

The liquid phase esterification of phenyl acetic acid with p -cresol over different metal cation exchanged montmorillonite nanoclays yields p -cresyl phenyl acetate. Different metal cation exchanged montmorillonite nanoclays (M n +  = Al 3+ , Zn 2+ , Mn 2+ , Fe 3+ , Cu 2+ ) were prepared and the catalytic activity was studied. The esterification reaction was conducted by varying molar ratio of the reactants, reaction time and catalyst amount on the yield of the ester. Among the different metal cation exchanged catalysts used, Al 3+ -montmorillonite nanoclay was found to be more active. The characterization of the material used was studied under different techniques, namely X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. The product obtained, p -cresyl phenyl acetate, was identified by thin-layer chromotography and confirmed by Fourier transform infrared, 1 H NMR and 13 C NMR. The regeneration activity of used catalyst was also investigated up to fourth generation.

Engineered barriers for radioactive waste confinement

Directory of Open Access Journals (Sweden)

Fernández, R.

2011-09-01

Full Text Available Nuclear power plants generate long-lived radioactive waste of high toxicity. The security assessment of repositories destined to definitive confinement of radioactive waste has been studied for several decades. Deep geological repositories are technically feasible and begin to be built by some pioneer countries. The scientific evaluation of interactions between the different engineered barriers is studied by laboratory experiments, natural analogues and modeling studies. The three methods are able to represent and validate the main geochemical processes that take place in the near field. This paper reviews the scientific and technical basis of the concept of geological disposal, with particular focus on the methods of study applied to the evaluation of geochemical stability of the bentonite barrier.

Las centrales nucleares generan residuos radiactivos de elevada peligrosidad y permanencia en el tiempo. La evaluación de la seguridad de repositorios destinados al alojamiento definitivo de estos residuos lleva estudiándose desde hace varias décadas. El almacenamiento geológico es técnicamente factible y empieza ya a desarrollarse en países pioneros. La evaluación científica de las interacciones entre las distintas barreras de ingeniería se estudia mediante ensayos de laboratorio, análisis de análogos naturales y modelos teóricos. Las tres vías de estudio son capaces de representar y validar los principales procesos geoquímicos que tienen lugar en el campo cercano al repositorio. Este artículo revisa los fundamentos científicos y técnicos del concepto de almacenamiento geológico detallando, en particular, los métodos de estudio aplicados a la evaluación de la estabilidad geoquímica de la barrera de bentonita.

Identifying the Barriers upon Development of Virtual Education in Engineering Majors (Case Study: The University of Isfahan)

Science.gov (United States)

Nikoonezhad, Sepideh; Nili, Mohammadreza; Esfahani, Ahmadreza Nasr

2015-01-01

The present study aims at investigating barriers upon development of virtual education in engineering majors at the University of Isfahan. The study has applied a mixed method (qualitative and quantitative) and its population consists all of the department members of the technical and engineering majors at the University of Isfahan including 125…

Synthesis and Characterization of CdS/TiO2-Montmorillonite Nanocomposite with Enhanced Visible-Light Absorption

OpenAIRE

Feng-shan Zhou; Dai-mei Chen; Bao-lin Cui; Wei-heng Wang

2014-01-01

Sodium montmorillonite (MMT) was chosen as the carrier; a serial of CdS/TiO2-MMT nanocomposites with enhanced visible-light absorption ability was prepared by hydrothermal synthesis method combination with semiconductor compound modification method. The samples are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible (UV-Vis) spectroscopy; the results showed that TiO2 and CdS nanoparticles were loaded on the surface of montmorillonite unifo...

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.

Performance Confirmation for the Engineered Barrier System. Report of a Workshop

International Nuclear Information System (INIS)

Bennett, David G.

2004-08-01

As part of preparations for review of future license applications, the Swedish Nuclear Power Inspectorate (SKI) organised a workshop on the engineered barrier system for the KBS-3 concept, focused on Performance Confirmation (PC). The workshop was held during 12 - 14 May, 2004 at Oskarshamn. The main purpose of the workshop was to identify key issues relating to the demonstration of long-term safety using a system of engineered barriers. The workshop began with introductory presentations on Performance Confirmation, on monitoring, and on long-term experiments in underground research laboratories. Working groups were then convened to discuss these topics and identify questions to put to the Swedish Nuclear Fuel and Waste Management Company (SKB) the following day. On the second day, SKB made several presentations, mainly on long-term experiments conducted at the Aespoe underground research laboratory. These presentations were followed by an informal session during which the questions identified by the working groups on the first day were discussed with SKB and its representatives. This report includes the questions identified by the working groups and a summary of the workshop discussions. Extended abstracts for the introductory presentations are included in an appendix. The conclusions and viewpoints presented in this report are those of one or several workshop participants. They do not necessarily coincide with those of SKI

Biogeochemical and engineered barriers for preventing spread of contaminants.

Science.gov (United States)

Baltrėnaitė, Edita; Lietuvninkas, Arvydas; Baltrėnas, Pranas

2018-02-01

The intensive industrial development and urbanization, as well as the negligible return of hazardous components to the deeper layers of the Earth, increases the contamination load on the noosphere (i.e., the new status of the biosphere, the development of which is mainly controlled by the conscious activity of a human being). The need for reducing the spread and mobility of contaminants is growing. The insights into the role of the tree in the reduction of contaminant mobility through its life cycle are presented to show an important function performed by the living matter and its products in reducing contamination. For maintaining the sustainable development, natural materials are often used as the media in the environmental protection technologies. However, due to increasing contamination intensity, the capacity of natural materials is not sufficiently high. Therefore, the popularity of engineered materials, such as biochar which is the thermochemically modified lignocellulosic product, is growing. The new approaches, based on using the contaminant footprint, as well as natural (biogeochemical) and engineered barriers for reducing contaminant migration and their application, are described in the paper.

Effect of thermal barrier coating with various blends of pumpkin seed oil methyl ester in DI diesel engine

Science.gov (United States)

Karthickeyan, V.; Balamurugan, P.

2017-10-01

The rise in oil prices, dependency on fossil fuels, degradation of non-renewable energy resources and global warming strives to find a low-carbon content alternative fuel to the conventional fuel. In the present work, Partially Stabilized Zirconia (PSZ) was used as a thermal barrier coating in piston head, cylinder head and intake and exhaust valves using plasma spray technique, which provided a rise in combustion chamber temperature. With the present study, the effects of thermal barrier coating on the blends of Pumpkin Seed Oil Methyl Ester (PSOME) were observed in both the coated and uncoated engine. Performance and emission characteristics of the PSOME in coated and uncoated engines were observed and compared. Increased thermal efficiency and reduced fuel consumption were observed for B25 and diesel in coated and uncoated engine. On comparing with the other biodiesel samples, B25 exhibited lower HC, NOx and smoke emissions in thermally coated engine than uncoated engine. After 100 h of operation, no anamolies were found in the thermally coated components except minor cracks were identified in the edges of the piston head.

First polarization-engineered compressively strained AlInGaN barrier enhancement-mode MISHFET

International Nuclear Information System (INIS)

Hahn, Herwig; Reuters, Ben; Wille, Ada; Ketteniss, Nico; Kalisch, Holger; Vescan, Andrei; Benkhelifa, Fouad; Ambacher, Oliver

2012-01-01

One current focus of research is the realization of GaN-based enhancement-mode devices. A novel approach for the realization of enhancement-mode behaviour is the utilization of polarization matching between the barrier and the GaN buffer. Yet, the utilization of a quaternary barrier combining polarization engineering together with a large conduction band offset has not been demonstrated so far. Here, epitaxially grown, compressively strained AlInGaN is applied as a nearly polarization-matched barrier layer on GaN resulting in enhancement-mode operation. The insulated-gate devices are fabricated gate-first with Al 2 O 3 as gate dielectric. Passivated metal insulator semiconductor heterostructure field effect transistors yielded threshold voltages (V th ) of up to +1 V. The devices withstand negative and positive gate-biased stress and a positive V th is maintained even after long-time negative bias stress. (paper)

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture

Directory of Open Access Journals (Sweden)

T. Karthikeya Sharma

2015-11-01

Full Text Available Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE. This paper investigates the effects of using argon (Ar gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine’s performance within the range studied.

Development of mechanistic sorption model and treatment of uncertainties for Ni sorption on montmorillonite/bentonite

International Nuclear Information System (INIS)

Ochs, Michael; Ganter, Charlotte; Tachi, Yukio; Suyama, Tadahiro; Yui, Mikazu

2011-02-01

Sorption and diffusion of radionuclides in buffer materials (bentonite) are the key processes in the safe geological disposal of radioactive waste, because migration of radionuclides in this barrier is expected to be diffusion-controlled and retarded by sorption processes. It is therefore necessary to understand the detailed/coupled processes of sorption and diffusion in compacted bentonite and develop mechanistic /predictive models, so that reliable parameters can be set under a variety of geochemical conditions relevant to performance assessment (PA). For this purpose, JAEA has developed the integrated sorption and diffusion (ISD) model/database in montmorillonite/bentonite systems. The main goal of the mechanistic model/database development is to provide a tool for a consistent explanation, prediction, and uncertainty assessment of K d as well as diffusion parameters needed for the quantification of radionuclide transport. The present report focuses on developing the thermodynamic sorption model (TSM) and on the quantification and handling of model uncertainties in applications, based on illustrating by example of Ni sorption on montmorillonite/bentonite. This includes 1) a summary of the present state of the art of thermodynamic sorption modeling, 2) a discussion of the selection of surface species and model design appropriate for the present purpose, 3) possible sources and representations of TSM uncertainties, and 4) details of modeling, testing and uncertainty evaluation for Ni sorption. Two fundamentally different approaches are presented and compared for representing TSM uncertainties: 1) TSM parameter uncertainties calculated by FITEQL optimization routines and some statistical procedure, 2) overall error estimated by direct comparison of modeled and experimental K d values. The overall error in K d is viewed as the best representation of model uncertainty in ISD model/database development. (author)

PEBS. Long-term performance of engineered barrier systems

Energy Technology Data Exchange (ETDEWEB)

Wieczorek, Klaus; Czaikowski, Oliver; Miehe, Ruediger

2014-12-15

The evolution of the engineered barrier system (EBS) of geological repositories for radioactive waste has been the subject of many national and international research programmes. The emphasis of the research activities was on the elaboration of a detailed understanding of the complex THMC processes, which are expected to evolve in the early post closure period in the near field. From the perspective of radiological long-term safety, an in-depth understanding of these coupled processes is of great significance, because the evolution of the EBS during the early post-closure phase may have a non-negligible impact on the radiological safety functions at the time when the canisters breach. Unexpected process interactions during the resaturation phase could impair the safety-relevant parameters in the EBS (e. g. swelling pressure, hydraulic conductivity, diffusivity).

Application of engineered sorbent barriers Summary of Laboratory Data for FY 1988

Energy Technology Data Exchange (ETDEWEB)

Freeman, H.D.; Jones, E.O.

1989-09-01

Laboratory studies were conducted in FY 1988 Pacific Northwest Laboratory to determine the effect of contact time, pH, solution to solid ratio, and particle size on the performance of a number of materials in adsorbing radioactive cobalt, strontium, and cesium. The laboratory studies were conducted to provide background information useful in designing an engineered sorbent barrier, which restricts the migration of radionuclides from low-level waste sites. Understanding how the variables affect the adsorption of ions on the sorbent materials is the key to estimating the performance of sorbent barriers under a variety of conditions. The scope of the studies was limited to three radionuclides and four sorbent materials, but the general approach can be used to evaluate other radionuclides and conditions. The sorbent materials evaluated in this study included clinoptilolite, activated carbon, bentonite clay, and Savannah River soil. The clinoptilolite and activated carbon were identified in previous studies as the most cost-effective materials for sorption of the three radionuclides under consideration. The bentonite clay was evaluated as a component of the barrier that could be used to modify the permeability of the barrier system. The Savannah River soil was used to represent soil from a humid site. 3 refs., 14 figs., 1 tab.

Engineered barrier durability: An issue for disposal near populated areas

International Nuclear Information System (INIS)

Porter, C.L.

1995-01-01

Under the current national policy for disposal of low-level radioactive waste (LLW) in the United States of America, each State is required to provide disposal capacity for the LLW generated within its borders. The formation of ''Compacts'' of several States is allowed if approved by Congress. Such forced regionalization of disposal facilities based on State boundaries results in some disposal facilities being sited near populated areas at locations with less than optimum site characteristics from a disposal standpoint. To compensate for this engineered barriers are included in the proposed designs. Portland cement based concrete (PCC), which is the dominant material for disposal vault designs, is degraded via many mechanisms, most of which are related to its permeability. The numerous uncertainties associated with the long-term performance of PCC has lead to many unsuccessful attempts to obtain public acceptance of proposed disposal facilities. These unsuccessful efforts have delayed establishing disposal capacity to the point that a crisis is looming on the horizon. This paper investigates the results of on-going research into the viability of commercially available, impermeable, mass-poured construction materials as an alternative to PCC in LLW disposal vaults. The results from testing and research on two such materials, concrete made from sulfur polymer cement (SPC) and ICOM (an epoxy based concrete) are reported. Material properties and test results include strength parameters, chemical resistance, porosity, permeability, deconability, radiation damage resistance, and biodegradation. The data indicates that with these alternative materials the uncertainties in predicting service life of an engineered barrier can be reduced

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).

Nonmetallic engineered barriers, their properties and role in a geologic repository for high level radioactive waste

International Nuclear Information System (INIS)

Lisy, F.

1994-01-01

The efficiency of engineered barrier systems depends to a great extent on the properties of the materials used. Backfill and sealing materials must fulfill certain requirements and criteria. They must feature low hydraulic conductivity, high retardation capacity, extremely good sorption properties for a wide range of radionuclides potentially leachable from the deposited waste, low permeability, good compatibility with engineered and natural barriers, good workability, and availability in the necessary quantity and at a reasonable price. Some basic properties are presented of materials which fulfill, to a considerable degree, these requirements and which are thus suggested as suitable backfills, sealings of buffers, namely clay- and cement-based materials (concretes, mortars, etc.). A brief information is also given on some other materials like bitumen, asphalt, etc. (Z.S.) 4 refs

Clays in natural and engineered barriers for radioactive waste confinement

International Nuclear Information System (INIS)

2007-01-01

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

Clays in natural and engineered barriers for radioactive waste confinement

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-07-01

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

Evaluation of Thermal Barrier and PS-200 Self-Lubricating Coatings in an Air-Cooled Rotary Engine

Science.gov (United States)

Moller, Paul S.

1995-01-01

This project provides an evaluation of the feasibility and desirability of applying a thermal barrier coating overlaid with a wear coating on the internal surfaces of the combustion area of rotary engines. Many experiments were conducted with different combinations of coatings applied to engine components of aluminum, iron and titanium, and the engines were run on a well-instrumented test stand. Significant improvements in specific fuel consumption were achieved and the wear coating, PS-200, which was invented at NASA's Lewis Research Center, held up well under severe test conditions.

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)

A biodegradable polymer nanocomposite: Mechanical and barrier properties

Science.gov (United States)

Lilichenko, N.; Maksimov, R. D.; Zicans, J.; Merijs Meri, R.; Plume, E.

2008-01-01

The preparation of an environmentally friendly nanocomposite based on plasticized potato starch and unmodified montmorillonite clay is described. Data on the influence of montmorillonite concentration on the mechanical properties of the materials obtained are reported. The effective elastic constants of the nanocomposites are calculated. The calculation results are compared with experimental data. The influence of montmorillonite content on the moisture permeability is also investigated.

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.

Barriers to the Uptake of Concurrent Engineering in the Nigerian Construction Industry

Directory of Open Access Journals (Sweden)

Nathaniel Anny Aniekwu

2012-12-01

engineering and also to compute the Kendall’s coefficient of concordance, which assess the levels of agreement among the judges on the consistency of the rankings. A Kendall’s coefficient of concordance of W=0.57365 was recorded. A lack of awareness emerged as the most important barrier against the integration of this concept into the Nigerian construction industry. The top five variables are all human factors that can be ameliorated by proper education.

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

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.

Engineered Barrier System - Manufacturing, Testing and Quality Assurance. Report from a Workshop

International Nuclear Information System (INIS)

2004-06-01

As part of preparations for review of future license applications, the Swedish Nuclear Power Inspectorate (SKI) organised a workshop on the engineered barrier system for the KBS-3 concept, with the focus on manufacturing, testing and quality assurance. The main purpose of the workshop was to identify critical issues in the demonstration of how long-term safety requirements could be fulfilled for the engineered barriers. The workshop included presentations related to engineered barrier manufacturing and testing held by external experts, and working group sessions to prepare questions to the Swedish Nuclear Fuel and Waste Management Co. (SKB). SKB presentations were followed by an informal questioning and discussion with SKB representatives. This report includes a presentation of the questions posed by the working groups, SKB's replies to these questions as well as a summary of the working group discussions. The conclusions and viewpoints presented in this report are those of one or several workshop participants. During the workshop many issues regarding manufacturing, testing and quality assurance of the engineered barriers were discussed. The central themes in the questions and discussions are summarised as follows: There is a need to specify how the functional requirements for the buffer and backfill will be achieved in practise. Issues of particular interest are material selection, compaction density, initial water content and manufacturing methods for bentonite blocks. A major problem that must be addressed is the long period required to obtain relevant results from large-scale testing. The uncertainties relating to the wetting and subsequent swelling processes of the bentonite buffer have implications for analysis of the canister. It is necessary to know now non-uniform the bentonite swelling pressure could be in a worst case pressure differential, in order to evaluate the sufficiency of 'as tested' canister performance. Regarding the copper shell of the

Role of uniform pore structure and high positive charges in the arsenate adsorption performance of Al13-modified montmorillonite

International Nuclear Information System (INIS)

Zhao, Shou; Feng, Chenghong; Huang, Xiangning; Li, Baohua; Niu, Junfeng; Shen, Zhenyao

2012-01-01

Highlights: ► Al 13 modification changes As(V) sorption mechanism of montmorillonites. ► Intercalated ion charges mainly affects As(V) adsorption kinetics. ► Uniform pore structure exhibit more excellent As(V) adsorption performance. - Abstract: Four modified montmorillonite adsorbents with varied Al 13 contents (i.e., Na-Mont, AC-Mont, PAC 20 -Mont, and Al 13 -Mont) were synthesized and characterized by N 2 adsorption/desorption, X-ray diffraction, and Fourier-transform infrared analyses. The arsenate adsorption performance of the four adsorbents were also investigated to determine the role of intercalated Al 13 , especially its high purity, high positive charge (+7), and special Keggin structure. With increased Al 13 content, the physicochemical properties (e.g., surface area, structural uniformity, basal spacing, and pore volume) and adsorption performance of the modified montmorillonites were significantly but disproportionately improved. The adsorption data well fitted the Freundlich and Redlich–Peterson isotherm model, whereas the kinetic data better correlated with the pseudo-second-order kinetic model. The arsenate sorption mechanism of the montmorillonites changed from physical to chemisorption after intercalation with Al 13 . Increasing charges of the intercalated ions enhanced the arsenate adsorption kinetics, but had minimal effect on the structural changes of the montmorillonites. The uniform pore structure formed by intercalation with high-purity Al 13 greatly enhanced the pore diffusion and adsorption rate of arsenate, resulting in the high adsorption performance of Al 13 -Mont.

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.

Coagulation processes of kaolinite and montmorillonite in calm, saline water

Science.gov (United States)

Zhang, Jin-Feng; Zhang, Qing-He; Maa, Jerome P.-Y.

2018-03-01

A three dimensional numerical model for simulating the coagulation processes of colloids has been performed by monitoring the time evolution of particle number concentration, the size distribution of aggregates, the averaged settling velocity, the collision frequency, and the collision efficiency in quiescent water with selected salinities. This model directly simulates all interaction forces between particles based on the lattice Boltzmann method (LBM) and the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, and thus, can reveal the collision and coagulation processes of colloidal suspensions. Although using perfect spherical particles in the modeling, the results were compared with those for kaolinite and montmorillonite suspensions to demonstrate the capability of simulating the responses of these particles with highly irregular shape. The averaged settling velocity of kaolinite aggregates in quiescent saline water reached a maximum of 0.16 mm/s when the salinity increasing to about 3, and then, exhibited little dependence on salinity thereafter. Model simulations results (by choosing specific values that represent kaolinite's characteristics) indicate a similar trend: rapid decrease of the particle number concentration (i.e., rapidly flocculated, and thus, settling velocity also increases rapidly) when salinity increases from 0 to 2, and then, only increased slightly when salinity was further increased from 5 to 20. The collision frequency for kaolinite only decreases slightly with increasing salinity because that the fluid density and viscosity increase slightly in sea water. It suggests that the collision efficiency for kaolinite rises rapidly at low salinities and levels off at high salinity. For montmorillonite, the settling velocity of aggregates in quiescent saline water continuedly increases to 0.022 mm/s over the whole salinity range 0-20, and the collision efficiency for montmorillonite rises with increasing salinities.

Development of the Canadian used fuel repository engineered barrier system

Energy Technology Data Exchange (ETDEWEB)

Hatton, C., E-mail: chatton@nwmo.ca [Nuclear Waste Management Organization, Toronto, ON (Canada)

2015-07-01

The Nuclear Waste Management Organization (NWMO) is responsible for the implementation of Adaptive Phased Management (APM), the federally-approved plan for the safe long-term management of Canada's used nuclear fuel. Under the APM plan, used nuclear fuel will ultimately be placed within a deep geological repository in a suitable rock formation. In implementing APM, the NWMO is committed to ensure consistency with international best practices in the development of its repository system, including any advances in technology. In 2012, the NWMO undertook an optimization study to look at both the design and manufacture of its engineered barriers. This study looked at current technologies for the design and manufacture of used fuel containers, placement technologies, repository design, and buffer and sealing systems, while taking into consideration the state of the art worldwide in repository design and acceptance. The result of that study is the current Canadian engineered barrier system, consisting of a 2.7 tonne used fuel container with a carbon-steel core, copper-coated surface and welded spherical heads. The used fuel container is encapsulated in a bentonite buffer box at the surface and then transferred underground. Once underground, the used fuel is placed into a repository room which is cut into the rock using traditional drill-and-blast technologies. This paper explains the logic for the selection of the container and sealing system design and the development of innovative technologies for their manufacture including the use of laser welding, cold spray and pulsed-electrodeposition copper coating for the manufacture of the used fuel container, isostatic presses for the production of the one-piece bentonite blocks, and slip-skid technologies for placement into the repository. (author)

Development of the Canadian used fuel repository engineered barrier system

International Nuclear Information System (INIS)

Hatton, C.

2015-01-01

The Nuclear Waste Management Organization (NWMO) is responsible for the implementation of Adaptive Phased Management (APM), the federally-approved plan for the safe long-term management of Canada's used nuclear fuel. Under the APM plan, used nuclear fuel will ultimately be placed within a deep geological repository in a suitable rock formation. In implementing APM, the NWMO is committed to ensure consistency with international best practices in the development of its repository system, including any advances in technology. In 2012, the NWMO undertook an optimization study to look at both the design and manufacture of its engineered barriers. This study looked at current technologies for the design and manufacture of used fuel containers, placement technologies, repository design, and buffer and sealing systems, while taking into consideration the state of the art worldwide in repository design and acceptance. The result of that study is the current Canadian engineered barrier system, consisting of a 2.7 tonne used fuel container with a carbon-steel core, copper-coated surface and welded spherical heads. The used fuel container is encapsulated in a bentonite buffer box at the surface and then transferred underground. Once underground, the used fuel is placed into a repository room which is cut into the rock using traditional drill-and-blast technologies. This paper explains the logic for the selection of the container and sealing system design and the development of innovative technologies for their manufacture including the use of laser welding, cold spray and pulsed-electrodeposition copper coating for the manufacture of the used fuel container, isostatic presses for the production of the one-piece bentonite blocks, and slip-skid technologies for placement into the repository. (author)

Fe(III)-EDDHA and -EDDHMA sorption on Ca-montmorillonite, ferrihydrite, and peat.

Science.gov (United States)

Hernández-Apaolaza, L; Lucena, J J

2001-11-01

The effectiveness of Fe chelates as Fe sources and carriers in soil can be severely limited by the adsorption of Fe chelates or chelating agents in the solid phase. To study this phenomenon, well-characterized peat, Ca-montmorillonite, and ferrihydrite were used as model compounds, and the adsorption of Fe-EDDHA and Fe-EDDHMA chelates were studied. Sorption isotherms for the meso and racemic isomers of these chelates on the soil materials are described. The variability of sorption with pH in peat and ferrihydrite was also determined because both have variable surface charge at different pH values. In montmorillonite, at low concentrations, the retention of Fe from the Fe-EDDHMA chelate is greater than the one of the Fe-EDDHA chelate. As well as the concentration increased, the inverse situation occurs. The behavior of both meso and racemic isomers of chelates in contact with Ca-montmorillonite is similar. The Fe-meso-EDDHA isomer was highly adsorbed on ferrihydrite, but the racemic isomer is not significantly retained by this oxide. For Fe-EDDHMA isomers, the racemic isomer was more retained by the oxide, but a small sorption of the racemic isomer was also observed. Results suggest that Fe-EDDHA chelates were more retained in peat than Fe-EDDHMA chelates. The most retained isomer of Fe-EDDHA was the meso isomer. For Fe-EDDHMA, the adsorption was very low for both racemic and meso isomers.

Possibility of ion-exchange column studies using stabilised montmorillonite-H aggregates

International Nuclear Information System (INIS)

Platzer, R.; Bittel, R.

1959-01-01

The conditions necessary for obtaining stable aggregates of montmorillonite-H, prepared without addition of organic flocculant, is discussed. These aggregates possess the same general ion-exchange properties as montmorillonite-H suspensions, about which many papers have been written. Their insolubility and their stable physical form enable them to be used in columns in exactly the same way as the usual organic ion exchangers. The examples of cation fixation and separation described in this report emphasize the similarities between the properties of this exchanger and those of organic cation-exchange resins, and open up possibilities for the extrapolation of the many investigations carried out on organic exchangers to mineral exchangers of this type. Amongst the essential differences to be remarked, we have shown that the properties of physical stability and chemical exchange remain the same at temperatures up to 300 deg. C, to a first approximation, under very intense γ irradiation. (author) [fr

Technology assessment guide for application of engineered sorbent barriers to low-level radioactive waste disposal sites

Energy Technology Data Exchange (ETDEWEB)

Freeman, H.D.; Jones, E.O.; Depner, J.P.

1989-06-01

An engineered sorbent barrier (ESB) uses sorbent materials (such as activated carbon or natural zeolites) to restrict migration of radionuclides from low-level waste sites. The permeability of the ESB allows moisture to pass while the sorbent material traps or absorbs contaminants. In contrast, waste sites with impermeable barriers could fill with water, especially those waste sites in humid climates. A sorbent barrier can be a simple, effective, and inexpensive method for restricting radionuclide migration. This report provides information and references to be used in assessing the sorbent barrier technology for low-level waste disposal. The ESB assessment is based on sorbent material and soil properties, site conditions, and waste properties and inventories. These data are used to estimate the thickness of the barrier needed to meet all performance requirements for the waste site. This document addresses the following areas: (1) site information required to assess the need and overall performance of a sorbent barrier; (2) selection and testing of sorbent materials and underlying soils; (3) use of radionuclide transport models to estimate the required barrier thickness and long-term performance under a variety of site conditions; (4) general considerations for construction and quality assurance; and (5) cost estimates for applying the barrier. 37 refs., 6 figs., 2 tabs.

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)

Identifying barriers to Science, Technology, Society and environment (STSE) educational goals and pedagogy in science education: A case study of UMASS Lowell undergraduate engineering

Science.gov (United States)

Phaneuf, Tiffany

The implementation of sustainable development in higher education is a global trend. Engineers, as gatekeepers of technological innovation, confront increasingly complex world issues ranging from economic and social to political and environmental. Recently, a multitude of government reports have argued that solving such complex problems requires changes in the pedagogy of engineering education, such as that prescribed by the Science, Technology, Society, and education (STS) movement that grew out of the environmental movement in the 70s. In STS students are engaged in the community by understanding that scientific progress is innately a sociopolitical process that involves dimensions of power, wealth and responsibility. United States accreditation criteria now demand "the broad education necessary to understand the impact of engineering solutions in a global, economic, environmental, and societal context" (ABET Engineering Accreditation Commission 2005). With such emphasis on STS education as necessary to address complex world issues, it is vital to assess the barriers in the traditional engineering curriculum that may inhibit the success of such educational reform. This study identifies barriers to STS goals and pedagogy in post secondary science education by using the Francis College of Engineering at UMASS Lowell as a single case study. The study draws on existing literature to develop a theoretical framework for assessing four hypothesized barriers to STS education in undergraduate engineering. Identification of barriers to STS education in engineering generates a critical reflection of post secondary science education and its role in preparing engineers to be active citizens in shaping a rapidly globalizing world. The study offers policy recommendations for enabling post secondary science education to incorporate STS education into its curriculum.

Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS)

International Nuclear Information System (INIS)

Steefel, Carl; Rutqvist, Jonny; Tsang, Chin-Fu; Liu, Hui-Hai; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

2010-01-01

Geological repositories for disposal of high-level nuclear wastes generally rely on a multi-barrier system to isolate radioactive wastes from the biosphere. The multi-barrier system typically consists of a natural barrier system, including repository host rock and its surrounding subsurface environment, and an engineering barrier system (EBS). EBS represents the man-made, engineered materials placed within a repository, including the waste form, waste canisters, buffer materials, backfill and seals (OECD, 2003). EBS plays a significant role in the containment and long-term retardation of radionuclide release. EBS is involved in complex thermal, hydrogeological, mechanical, chemical and biological processes, such as heat release due to radionuclide decay, multiphase flow (including gas release due to canister corrosion), swelling of buffer materials, radionuclide diffusive transport, waste dissolution and chemical reactions. All these processes are related to each other. An in-depth understanding of these coupled processes is critical for the performance assessment (PA) for EBS and the entire repository. Within the EBS group of Used Fuel Disposition (UFD) Campaign, LBNL is currently focused on (1) thermal-hydraulic-mechanical-chemical (THMC) processes in buffer materials (bentonite) and (2) diffusive transport in EBS associated with clay host rock, with a long-term goal to develop a full understanding of (and needed modeling capabilities to simulate) impacts of coupled processes on radionuclide transport in different components of EBS, as well as the interaction between near-field host rock (e.g., clay) and EBS and how they effect radionuclide release. This final report documents the progress that LBNL has made in its focus areas. Specifically, Section 2 summarizes progress on literature review for THMC processes and reactive-diffusive radionuclide transport in bentonite. The literature review provides a picture of the state-of-the-art of the relevant research areas

Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS)

Energy Technology Data Exchange (ETDEWEB)

Steefel, Carl; Rutqvist, Jonny; Tsang, Chin-Fu; Liu, Hui-Hai; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

2010-08-31

Geological repositories for disposal of high-level nuclear wastes generally rely on a multi-barrier system to isolate radioactive wastes from the biosphere. The multi-barrier system typically consists of a natural barrier system, including repository host rock and its surrounding subsurface environment, and an engineering barrier system (EBS). EBS represents the man-made, engineered materials placed within a repository, including the waste form, waste canisters, buffer materials, backfill and seals (OECD, 2003). EBS plays a significant role in the containment and long-term retardation of radionuclide release. EBS is involved in complex thermal, hydrogeological, mechanical, chemical and biological processes, such as heat release due to radionuclide decay, multiphase flow (including gas release due to canister corrosion), swelling of buffer materials, radionuclide diffusive transport, waste dissolution and chemical reactions. All these processes are related to each other. An in-depth understanding of these coupled processes is critical for the performance assessment (PA) for EBS and the entire repository. Within the EBS group of Used Fuel Disposition (UFD) Campaign, LBNL is currently focused on (1) thermal-hydraulic-mechanical-chemical (THMC) processes in buffer materials (bentonite) and (2) diffusive transport in EBS associated with clay host rock, with a long-term goal to develop a full understanding of (and needed modeling capabilities to simulate) impacts of coupled processes on radionuclide transport in different components of EBS, as well as the interaction between near-field host rock (e.g., clay) and EBS and how they effect radionuclide release. This final report documents the progress that LBNL has made in its focus areas. Specifically, Section 2 summarizes progress on literature review for THMC processes and reactive-diffusive radionuclide transport in bentonite. The literature review provides a picture of the state-of-the-art of the relevant research areas

Magnetic Materials: Novel Monitors of Long-Term Evolution of Engineered Barrier Systems

Directory of Open Access Journals (Sweden)

Simon L. Harley

2016-12-01

Full Text Available Most safety cases for the deep geological disposal of radioactive waste are reliant on the swelling of bentonite in the engineered barrier system as it saturates with groundwater. Assurance of safety therefore requires effective monitoring of bentonite saturation. The time- and fluid-dependent corrosion of synthetic magnets embedded in bentonite is demonstrated here to provide a novel and passive means of monitoring saturation. Experiments have been conducted at 70 °C in which neo magnets, AlNiCo magnets, and ferrite magnets have been reacted with saline (NaCl, KCl, CaCl2 solutions and alkaline fluids (NaOH, KOH, Ca(OH2 solutions; pH = 12 in the presence of bentonite. Nd-Fe-B magnets undergo extensive corrosion that results in a dramatic change from ferromagnetic to superparamagnetic behaviour concomitant with bentonite saturation. AlNiCo magnets in saline solutions show corrosion but only limited decreases in their magnetic intensities, and ferrite magnets are essentially unreactive on the experimental timescales, retaining their initial magnetic properties. For all magnets the impact of their corrosion on bentonite swelling is negligible; alteration of bentonite is essentially governed by the applied fluid composition. In principle, synthetic magnet arrays can, with further development, be designed and embedded in bentonite to monitor its fluid saturation without compromising the integrity of the engineered barrier system itself.

HTCC-Modified Nanoclay for Tissue Engineering Applications: A Synergistic Cell Growth and Antibacterial Efficiency

Directory of Open Access Journals (Sweden)

Majid Aliabadi

2013-01-01

Full Text Available This paper deals with the synthesis of a biocompatible chitosan ammonium salt N-(2-hydroxy propyl-3-trimethylammonium chitosan chloride (HTCC and using it in montmorillonite ion-exchange process. HTCC-modified montmorillonite (Mt with different chemical ratios was successfully synthesized, and their characteristics have been verified by XRD and FTIR analyses. Produced samples have been evaluated in terms of antibacterial efficiency and biocompatibility (cell culture test. Antibacterial efficiency of synthesized HTCC/Mt samples has been confirmed against both gram negative bacteria (Escherichia coli and gram positive bacteria (Staphylococcus aureus. The results disclosed that the antibacterial efficiency of HTCC-modified montmorillonite was unexpectedly even more than HTCC. This excellent synergistic effect has been referred to entrapping bacteria between the intercalated structures of HTCC-modified montmorillonite. Then HTCC on clay layers can seriously attack and damage the entrapped bacteria. An extraordinary biocompatibility, cell attachment, and cell growth even more than tissue culture polystyrene (TCPS have been recorded in the case of this novel kind of modified clay. Due to existing concerns about serious and chronic infections after implant placement, this natural-based bioactive and antibacterial modified clay can be used in electrospun nanofibers and other polymeric implants with promising mechanical properties for tissue engineering applications.

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.)

Engineered Barrier System performance requirements systems study report. Revision 02

International Nuclear Information System (INIS)

Balady, M.A.

1997-01-01

This study evaluates the current design concept for the Engineered Barrier System (EBS), in concert with the current understanding of the geologic setting to assess whether enhancements to the required performance of the EBS are necessary. The performance assessment calculations are performed by coupling the EBS with the geologic setting based on the models (some of which were updated for this study) and assumptions used for the 1995 Total System Performance Assessment (TSPA). The need for enhancements is determined by comparing the performance assessment results against the EBS related performance requirements. Subsystem quantitative performance requirements related to the EBS include the requirement to allow no more than 1% of the waste packages (WPs) to fail before 1,000 years after permanent closure of the repository, as well as a requirement to control the release rate of radionuclides from the EBS. The EBS performance enhancements considered included additional engineered components as well as evaluating additional performance available from existing design features but for which no performance credit is currently being taken

Engineered Barrier System performance requirements systems study report. Revision 02

Energy Technology Data Exchange (ETDEWEB)

Balady, M.A.

1997-01-14

This study evaluates the current design concept for the Engineered Barrier System (EBS), in concert with the current understanding of the geologic setting to assess whether enhancements to the required performance of the EBS are necessary. The performance assessment calculations are performed by coupling the EBS with the geologic setting based on the models (some of which were updated for this study) and assumptions used for the 1995 Total System Performance Assessment (TSPA). The need for enhancements is determined by comparing the performance assessment results against the EBS related performance requirements. Subsystem quantitative performance requirements related to the EBS include the requirement to allow no more than 1% of the waste packages (WPs) to fail before 1,000 years after permanent closure of the repository, as well as a requirement to control the release rate of radionuclides from the EBS. The EBS performance enhancements considered included additional engineered components as well as evaluating additional performance available from existing design features but for which no performance credit is currently being taken.

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.

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)

Development of plasticised nano-biocomposites of poly(hydroxybutyrate-co-hydroxyvalerate)/montmorillonite organically modified (PHBV/OMMT)

International Nuclear Information System (INIS)

Correa, M.C.; Pollet, E.; Averous, L.; Agnell, J.A.M.; Nascente, P.A.P.

2010-01-01

Several studies have aimed to improve the properties of biopolymers by the incorporation of nano-sized fillers, such as organo-modified montmorillonite (OMMT), to form nano-biocomposites. The objective of this work is to investigate the influence of acetyl tributyl citrate (ATBC) plasticizer with PHBV/OMMT nano-biocomposites aiming at improving their behavior. The materials PHBV, OMMT (C30B), and ATBC were provided by PHB Industrial S/A (Brazil), Southern Clay Products (USA), and Scandiflex S/A (Brazil), respectively. In this study the processing parameters and the formulations were controlled, pursuing materials with good mechanical and barrier properties with high biodegradability and with greater ease of processing. The analysis of the results obtained by TGA, GPC, WAXS, DSC, mechanical properties, and biodegradability lead to the conclusion that the addition of plasticizer in nanobiocomposites improved processability and did not influence the state of nano-sized load dispersion. It can be concluded that the addition of plasticizer is a good alternative to the processability of nanocomposites of PHAs. (author)

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.

Bi-hybrid coatings: polyaniline-montmorillonite filler in organic-inorganic polymer matrix

Czech Academy of Sciences Publication Activity Database

Špírková, Milena; Bober, Patrycja; Kotek, Jiří; Stejskal, Jaroslav

2013-01-01

Roč. 67, č. 8 (2013), s. 1020-1027 ISSN 0366-6352 R&D Projects: GA ČR GA202/09/1626; GA AV ČR(CZ) IAAX08240901 Institutional support: RVO:61389013 Keywords : polyaniline * montmorillonite * organic-inorganic composite Subject RIV: JI - Composite Materials Impact factor: 1.193, year: 2013

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

Assessment and Measurements of Degradation Processes in the Engineering Barriers of LILW Repository

International Nuclear Information System (INIS)

Zeleznik, N.; Sajna, A.; Petkovsek, B.

2013-01-01

In 2009 the Slovenian national agency for radwaste management (ARAO) adopted the national spatial plan for the low and intermediate level waste (LILW) repository to be located in Krsko municipality near NPP Krsko. The selected option for disposal was based on a silo type structure for the near surface disposal facility that will be situated close to a saturated aquifer. The soil in the region can be described as silt that extends a few hundred meters deep. The silt also contains sections of sand or clay. As the possibility exists that the natural geological barrier system will not be able to contain radionuclide migration it is a pre requisite that the proposed LILW repository must install engineered barriers. Research on different cementation materials are currently underway in order to find sustainable materials for the manufacturing of engineered barriers for the repository (silo, backfilling, concrete containers). The research also includes the assessment of possible site specific degradation processes in order to provide a methodology for the selection of appropriate locally available materials that will minimize the degradation processes. The research methodology was based on studying the characteristics (workability, compressive strength), durability (resistance to penetration of water, freeze/thaw resistance, resistance to groundwater), rheology (heat of hydration, autogenous and concrete shrinkage) and reinforcement corrosion of different concrete compositions. The characterization results were used to develop a numerical model for degradation processes to be found in the current concrete compositions. Although initial results indicated that the current concrete compositions are satisfactory, the research must be extended to the addition of binder materials to improve the characteristics of the manufactures concrete before degradation processes can be studied. (author)

Synergistic reinforcing effect of TiO2 and montmorillonite on potato starch nanocomposite films: Thermal, mechanical and barrier properties.

Science.gov (United States)

Oleyaei, Seyed Amir; Almasi, Hadi; Ghanbarzadeh, Babak; Moayedi, Ali Akbar

2016-11-05

In this study, ternary potato starch (PS) bionanocomposite films containing two types of nanoparticles, sodium montmorillonite (MMT), one-dimensional (1D) clay platelets, (3 and 5wt%) and TiO2, three-dimensional (3D) nanospheres, (0.5, 1 and 2wt%), are prepared using solvent casting method. X-ray diffraction (XRD) test confirms the completely exfoliated structure formed in the PS-MMT nanocomposites containing 3 and 5% MMT. The success of the formation of new hydrogen bonds between the hydroxyl groups of starch and nanofillers is confirmed by Fourier transform infrared (FTIR) spectroscopy. Tensile strength (TS), elongation at break (EB), glass transition temperature (Tg), and melting point (Tm) of the films are also enhanced after MMT and TiO2 incorporation. The water vapor permeability (WVP) and the visible, UVA, UVB and UVC lights transmittance decreases upon TiO2 and MMT content increasing. Generally, a synergistic effect is observed between MMT and TiO2 at lower concentrations of MMT. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermal Emission of Alkali Metal Ions from Al30-Pillared Montmorillonite Studied by Mass Spectrometric Method.

Science.gov (United States)

Motalov, V B; Karasev, N S; Ovchinnikov, N L; Butman, M F

2017-01-01

The thermal emission of alkali metal ions from Al 30 -pillared montmorillonite in comparison with its natural form was studied by mass spectrometry in the temperature range 770-930 K. The measurements were carried out on a magnetic mass spectrometer MI-1201. For natural montmorillonite, the densities of the emission currents ( j ) decrease in the mass spectrum in the following sequence (T = 805 K, A/cm 2 ): K + (4.55 · 10 -14 ), Cs + (9.72 · 10 -15 ), Rb + (1.13 · 10 -15 ), Na + (1.75 · 10 -16 ), Li + (3.37 · 10 -17 ). For Al 30 -pillared montmorillonite, thermionic emission undergoes temperature-time changes. In the low-temperature section of the investigated range (770-805 K), the value of j increases substantially for all ions in comparison with natural montmorillonite (T = 805 K, A/cm 2 ): Cs + (6.47 · 10 -13 ), K + (9.44 · 10 -14 ), Na + (3.34 · 10 -15 ), Rb + (1.77 · 10 -15 ), and Li + (4.59 · 10 -16 ). A reversible anomaly is observed in the temperature range 805-832 K: with increasing temperature, the value of j of alkaline ions falls abruptly. This effect increases with increasing ionic radius of M + . After a long heating-up period, this anomaly disappears and the ln j - 1/ T dependence acquires a classical linear form. The results are interpreted from the point of view of the dependence of the efficiency of thermionic emission on the phase transformations of pillars.

Validation of the Performance of Engineered Barriers

International Nuclear Information System (INIS)

Choi, Jongwon; Cho, Wonjin; Kwon, Sangki

2012-04-01

To study the thermal-hydro-mechanical (THM) and thermal-hydro-mechanical-chemical (THMC) behavior of engineered barrier system (EBS), the engineering scale experiments, KENTEX and KENTEX-C were conducted to investigate THM and THMC behavior in the buffer. The computer modelling and simulation programmes were developed to analyze the distribution of temperature, water content, total pressure and the measured data on the migration behavior of anion and cation. In-situ heater test were performed to investigate the effect of the ventilation, thermal characteristics of EDZ, and effect of the anisotropy of rock mass and joint in addition to the investigation of the thermo-mechanical behavior in rock mass. The geophysics exploration and in-situ field tests were carried out to investigate the range of EDZ and its effects on the mechanical properties of rock. Subsequently, crack propagation characteristics and dynamic material properties of jointed rock mass in KURT were measured. Concurrently, the in-situ experiments were performed in the KURT to investigate the change of hydraulic properties in EDZ. The stainless steel molds are manufactured to fabricate the buffer blocks with various shapes. The experiments are carried out to check the mechanical properties, the workability for installation of the fabricated blocks and to investigate the resaturation processes. The state of the technology on application of cementitious materials to the HLW repository was analysed and the optimized low-pH cement recipe was obtained. And the material properties of low-pH and high-pH cement grouts were evaluated based on the grout recipes of ONKALO in Finland. The KURT was operated, and the various technical supports were provided to the in-situ experiments which were carried at KURT

Examining E-Learning Barriers As Perceived By Faculty 
Members Of Engineering Colleges In The Jordanian Universities

OpenAIRE

Muhammad K. AL-ALAWNEH,

2014-01-01

Employing computer's technology that includes e-learning system in the field of Engineering is a vital issue which needs to be discussed. Therefore, this study purposed to examine e-learning barriers as perceived by faculty members of engineering in three major universities in Jordan (Yarmouk University, Jordan University of Science and Technology, and Al-Balqaa Applied University) in the second semester of 2012. The study's instrument was distributed to collect the data from a sam...

Deep disposal of high activity radioactive wastes: the study of engineered and geological barriers behaviour

International Nuclear Information System (INIS)

Yu Jun; Cui; Delage, P.; Laure, E. de; Behrouz, Gatmiri; Sulem, J.; Anh Minh, Tang

2008-09-01

One option for the isolation of high activity and long lived radioactive wastes is the disposal of the vitrified waste containers in galleries dug inside impermeable rocks of the deep underground (granite, argillite, salt). The multi-barrier isolation concept is based on the use of successive barriers to avoid the migration of radionuclides towards the biosphere (container envelope, engineered barrier made of compacted swelling clay, and host rock). In parallel to the works carried out in underground laboratories, experiments and simulation works are performed in order to understand the behaviour of storage facilities and barriers under the effects of constraints, water fluxes and temperature changes. In this context, the UR Navier geotechnical team (CERMES), a joint research unit of Ecole des Ponts ParisTech and LCPC, has been working for more than 15 years on this topic for various contractors. These works are based on original experimental devices allowing to identify the thermo-hydro-mechanical phenomena and thereafter to model them. This dossier presents a summary of these works. (J.S.)

Execution techniques for high level radioactive waste disposal. 4. Design and manufacturing procedure of engineered barriers

International Nuclear Information System (INIS)

Ogata, Nobuhide; Kosaki, Akio; Ueda, Hiroyoshi; Asano, Hidekazu; Takao, Hajime

1999-01-01

Ensuring the physical integrity of engineered barriers for an extremely long time period is necessary for geological disposal of high-level radioactive wastes. This report describes the design process and the designed configurations of both overpack and buffer as engineered barriers. Manufacturing procedure, quality control and inspection methods are also summarized. Carbon steel was selected as a structural material of the overpack and the specification of the overpack was determined assuming disposal in the depths of 1000 m below surface of crystalline rock site. The mixture of bentonite and sand (80% sodium bentonite and 20% silica sand by mass) was selected as material for a buffer from mainly its permeability and characteristics of self-sealing of a gap occurred in construction work. Welding method of a lid onto the main body of the overpack, uniting method of a corrosion-resistance layer and the structural component in the case of a composite overpack and manufacturing procedures of both blocks-type and monolithic-type buffers are also investigated. (author)

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)

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.

Sorption of triclosan onto activated carbon, kaolinite and montmorillonite: effects of pH, ionic strength, and humic acid.

Science.gov (United States)

Behera, Shishir Kumar; Oh, Seok-Young; Park, Hung-Suck

2010-07-15

Sorption of triclosan on three sorbents, viz., activated carbon, kaolinite and montmorillonite was studied as a function of pH, ionic strength and humic acid (HA) concentration through controlled batch experiments. Triclosan sorption was found to be higher in the acidic pH range, as varying pH showed significant influence on the surface charge of the sorbents and degree of ionization of the sorbate. Sorption capacity of the sorbents increased with an increase in the ionic strength of solution. At low pH (pH 3), the overall increase in triclosan sorption was 1.2, approximately 4 and 3.5 times, respectively for activated carbon, kaolinite and montmorillonite when ionic strength was increased from 1x10(-3) to 5x10(-1) M. Triclosan sorption onto activated carbon decreased from 31.4 to 10.6 mg g(-1) by increasing the HA concentration to 200 mg C L(-1). However, during sorption onto kaolinite and montmorillonite, the effect of HA was very complex probably due to (i) hydrophobicity (log K(ow)=4.76) of triclosan; and (ii) complexation of HA with triclosan. Though triclosan sorption onto activated carbon is higher, the potential of kaolinite and montmorillonite in controlling the transport of triclosan in subsurface environment can still be appreciable. 2010 Elsevier B.V. All rights reserved.

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.

Eco-Friendly Magnetic Iron Oxide Pillared Montmorillonite for Advanced Catalytic Degradation of Dichlorophenol

Science.gov (United States)

Eco-friendly pillared montmorillonites, in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties that are applicable for environmental decontamination. Completely “green” and effective composite was synthesized using mild reactio...

Engineered barrier system and waste package design concepts for a potential geologic repository at Yucca Mountain

International Nuclear Information System (INIS)

Short, D.W.; Ruffner, D.J.; Jardine, L.J.

1991-10-01

We are using an iterative process to develop preliminary concept descriptions for the Engineered Barrier System and waste-package components for the potential geologic repository at Yucca Mountain. The process allows multiple design concepts to be developed subject to major constraints, requirements, and assumptions. Involved in the highly interactive and interdependent steps of the process are technical specialists in engineering, metallic and nonmetallic materials, chemistry, geomechanics, hydrology, and geochemistry. We have developed preliminary design concepts that satisfy both technical and nontechnical (e.g., programmatic or policy) requirements

Fungal biomineralization of montmorillonite and goethite to short-range-ordered minerals

Science.gov (United States)

Li, Huan; Hu, Shuijin; Polizzotto, Matthew L.; Chang, Xiaoli; Shen, Qirong; Ran, Wei; Yu, Guanghui

2016-10-01

Highly reactive nano-scale minerals, e.g., short-range-ordered minerals (SROs) and other nanoparticles, play an important role in soil carbon (C) retention. Yet, the mechanisms that govern biomineralization from bulk minerals to highly reactive nano-scale minerals remain largely unexplored, which critically hinders our efforts toward managing nano-scale minerals for soil C retention. Here we report the results from a study that explores structural changes during Aspergillus fumigatus Z5 transformation of montmorillonite and goethite to SROs. We examined the morphology and structure of nano-scale minerals, using high-resolution transmission electron microscopy, time-resolved solid-state 27Al and 29Si NMR, and Fe K-edge X-ray absorption fine structure spectroscopy combined with two dimensional correlation spectroscopy (2D COS) analysis. Our results showed that after a 48-h cultivation of montmorillonite and goethite with Z5, new biogenic intracellular and extracellular reactive nano-scale minerals with a size of 3-5 nm became abundant. Analysis of 2D COS further suggested that montmorillonite and goethite were the precursors of the dominant biogenic nano-scale minerals. Carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectra and their deconvolution results demonstrated that during fungus Z5 growth, carboxylic C (288.4-289.1 eV) was the dominant organic group, accounting for approximately 34% and 59% in the medium and aggregates, respectively. This result suggested that high percentage of the production of organic acids during the growth of Z5 was the driving factor for structural changes during biomineralization. This is, to the best of our knowledge, the first report of the structural characterization of nano-scale minerals by 2D COS, highlighting its potential to elucidate biomineralization pathways and thus identify the precursors of nano-scale minerals.

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)

Test Plan to Assess Fire Effects on the Function of an Engineered Surface Barrier

International Nuclear Information System (INIS)

Ward, Anderson L.; Berlin, Gregory T.; Cammann, Jerry W.; Leary, Kevin D.; Link, Steven O.

2008-01-01

Wildfire is a frequent perturbation in shrub steppe ecosystems, altering the flora, fauna, atmosphere, and soil of these systems. Research on the fire effects has focused mostly on natural ecosystems with essentially no attention on engineered systems like surface barriers. The scope of the project is to use a simulated wildfire to induce changes in an engineered surface barrier and document the effects on barrier performance. The main objective is to quantify the effects of burning and the resulting post-fire conditions on alterations in soil physical properties; hydrologic response, particularly the water balance; geochemical properties; and biological properties. A secondary objective is to use the lessons learned to maximize fire protection in the design of long-term monitoring systems based on electronic sensors. A simulated wildfire will be initiated, controlled and monitored at the 200-BP-1 barrier in collaboration with the Hanford Fire Department during the fall of 2008. The north half of the barrier will be divided into nine 12 x 12 m plots, each of which will be randomly assigned a fuel load of 2 kg m-2 or 4 kg m-2. Each plot will be ignited around the perimeter and flames allowed to carry to the centre. Any remaining unburned vegetation will be manually burned off using a drip torch. Progress of the fire and its effects will be monitored using point measurements of thermal, hydrologic, and biotic variables. Three measures of fire intensity will be used to characterize fire behavior: (1) flame height, (2) the maximum temperature at three vertical profile levels, and (3) total duration of elevated temperature at these levels. Pre-burn plant information, including species diversity, plant height, and canopy diameter will be measured on shrubs from the plots to be burned and from control plots at the McGee ranch. General assessments of shrub survival, recovery, and recruitment will be made after the fire. Near-surface soil samples will be collected pre- and

Test Plan to Assess Fire Effects on the Function of an Engineered Surface Barrier

Energy Technology Data Exchange (ETDEWEB)

Ward, Anderson L.; Berlin, Gregory T.; Cammann, Jerry W.; Leary, Kevin D.; Link, Steven O.

2008-09-29

Wildfire is a frequent perturbation in shrub steppe ecosystems, altering the flora, fauna, atmosphere, and soil of these systems. Research on the fire effects has focused mostly on natural ecosystems with essentially no attention on engineered systems like surface barriers. The scope of the project is to use a simulated wildfire to induce changes in an engineered surface barrier and document the effects on barrier performance. The main objective is to quantify the effects of burning and the resulting post-fire conditions on alterations in soil physical properties; hydrologic response, particularly the water balance; geochemical properties; and biological properties. A secondary objective is to use the lessons learned to maximize fire protection in the design of long-term monitoring systems based on electronic sensors. A simulated wildfire will be initiated, controlled and monitored at the 200-BP-1 barrier in collaboration with the Hanford Fire Department during the fall of 2008. The north half of the barrier will be divided into nine 12 x 12 m plots, each of which will be randomly assigned a fuel load of 2 kg m-2 or 4 kg m-2. Each plot will be ignited around the perimeter and flames allowed to carry to the centre. Any remaining unburned vegetation will be manually burned off using a drip torch. Progress of the fire and its effects will be monitored using point measurements of thermal, hydrologic, and biotic variables. Three measures of fire intensity will be used to characterize fire behavior: (1) flame height, (2) the maximum temperature at three vertical profile levels, and (3) total duration of elevated temperature at these levels. Pre-burn plant information, including species diversity, plant height, and canopy diameter will be measured on shrubs from the plots to be burned and from control plots at the McGee ranch. General assessments of shrub survival, recovery, and recruitment will be made after the fire. Near-surface soil samples will be collected pre- and

Starch/poly (butylene adipate-co-terephthalate/montmorillonite films produced by blow extrusion

Directory of Open Access Journals (Sweden)

Rodrigo A. L. Santos

2014-07-01

Full Text Available This study aims to prepare biodegradable films from cassava starch, poly (butylene adipate-co-terephthalate (PBAT, and montmorillonite (MMT using blow-extrusion process and analyze the effects of different types and concentrations of MMT on the microstructure, physicochemical, and mechanical properties of the resulting films. The films were produced by blending 30% of PBAT with glycerol (17.5%, starch (49.0-52.5%, and four different types of montmorillonite (Cloisite® Na+, 10A, 15A, and 30B at two different concentrations (1.75% and 3.5%. All the films prepared in this study showed an increase in the basal spacing of MMT layers. In particular, the films with 10A and 30B showed the highest increase in intercalation basal spacing, suggesting the formation of intercalated composites. The addition of nanoclays decreased the elongation of films. The addition of Cloisite® 10A resulted in films with the lowest WVP values and the highest stability to water adsorption under different RH conditions.

AN ANALYSIS OF THE THERMAL AND MECHANICAL BEHAVIOR OF ENGINEERED BARRIERS IN A HIGH-LEVEL RADIOACTIVE WASTE REPOSITORY

Directory of Open Access Journals (Sweden)

S. KWON

2013-02-01

Full Text Available Adequate design of engineered barriers, including canister, buffer and backfill, is important for the safe disposal of high-level radioactive waste. Three-dimensional computer simulations were carried out under different condition to examine the thermal and mechanical behavior of engineered barriers and rock mass. The research looked at five areas of importance, the effect of the swelling pressure, water content of buffer, density of compacted bentonite, emplacement type and the selection of failure criteria. The results highlighted the need to consider tensile stress in the outer shell of a canister due to thermal expansion of the canister and the swelling pressure from the buffer for a more reliable design of an underground repository system. In addition, an adequate failure criterion should be used for the buffer and backfill.

An analysis of the thermal and mechanical behavior of engineered barriers in a high-level radioactive waste repository

International Nuclear Information System (INIS)

Kwon, S.; Cho, W. J.; Lee, J. O.

2013-01-01

Adequate design of engineered barriers, including canister, buffer and backfill, is important for the safe disposal of high level radioactive waste. Three-dimensional computer simulations were carried out under different condition to examine the thermal and mechanical behavior of engineered barriers and rock mass. The research looked at five areas of importance, the effect of the swelling pressure, water content of buffer, density of compacted bentonite, emplacement type and the selection of failure criteria. The results highlighted the need to consider tensile stress in the outer shell of a canister due to thermal expansion of the canister and the swelling pressure from the buffer for a more reliable design of an underground repository system. In addition, an adequate failure criterion should be used for the buffer and backfill.

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

KAUST Repository

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

2017-01-01

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

Thermal Emission of Alkali Metal Ions from Al30-Pillared Montmorillonite Studied by Mass Spectrometric Method

Directory of Open Access Journals (Sweden)

V. B. Motalov

2017-01-01

Full Text Available The thermal emission of alkali metal ions from Al30-pillared montmorillonite in comparison with its natural form was studied by mass spectrometry in the temperature range 770–930 K. The measurements were carried out on a magnetic mass spectrometer MI-1201. For natural montmorillonite, the densities of the emission currents (j decrease in the mass spectrum in the following sequence (T = 805 K, A/cm2: K+ (4.55 · 10−14, Cs+ (9.72 · 10−15, Rb+ (1.13 · 10−15, Na+ (1.75 · 10−16, Li+ (3.37 · 10−17. For Al30-pillared montmorillonite, thermionic emission undergoes temperature-time changes. In the low-temperature section of the investigated range (770–805 K, the value of j increases substantially for all ions in comparison with natural montmorillonite (T = 805 K, A/cm2: Cs+ (6.47 · 10−13, K+ (9.44 · 10−14, Na+ (3.34 · 10−15, Rb+ (1.77 · 10−15, and Li+ (4.59 · 10−16. A reversible anomaly is observed in the temperature range 805–832 K: with increasing temperature, the value of j of alkaline ions falls abruptly. This effect increases with increasing ionic radius of M+. After a long heating-up period, this anomaly disappears and the lnj-1/T dependence acquires a classical linear form. The results are interpreted from the point of view of the dependence of the efficiency of thermionic emission on the phase transformations of pillars.

Nanocomposites chitosan/montmorillonite for drug delivery system

International Nuclear Information System (INIS)

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

2009-01-01

In drugs delivery system the incorporation of an inorganic nanophase in polymer matrix, i.e. production of an inorganic-organic nanocomposite is an attractive alternative to obtain a constant release rate for a prolonged time. This study was performed to obtain films of nanocomposites Chitosan/montmorillonite intercalation by the technique of solution in the proportions of 1:1, 5:1 and 10:1. The nanocomposites were characterized by infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. The results indicated that the feasibility of obtaining films of nanocomposites exfoliate. Among the suggested applications for films developed in this study includes them use for drugs delivery system. (author)

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

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

Green Synthesis of Carvenone by Montmorillonite-Catalyzed Isomerization of 1,2-Limonene Oxide

DEFF Research Database (Denmark)

Nguyen, Thao-Tran Thi; Chau, Duy-Khiem Nguyen; Duus, Fritz

2013-01-01

Montmorillonite was considered as a good heterogeneous catalyst for the isomerization of 1,2-limonene oxide into car-venone under solvent-free condition. Both conventional heating and green activations were tested in this research. The microwave-assisted isomerization afforded carvenone in high...

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

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

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

Effect of type and content of modified montmorillonite on the structure and properties of bio-nanocomposite films based on soy protein isolate and montmorillonite.

Science.gov (United States)

Kumar, P; Sandeep, K P; Alavi, S; Truong, V D; Gorga, R E

2010-06-01

The nonbiodegradable and nonrenewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and modified montmorillonite (MMT) were prepared using melt extrusion. The effect of different type (Cloisite 20A and Cloisite 30B) and content (0% to 15%) of modified MMT on the structure (degree of intercalation and exfoliation) and properties (color, mechanical, dynamic mechanical, thermal stability, and water vapor permeability) of SPI-MMT bio-nanocomposite films were investigated. Extrusion of SPI and modified MMTs resulted in bio-nanocomposites with exfoliated structures at lower MMT content (5%). At higher MMT content (15%), the structure of bio-nanocomposites ranged from intercalated for Cloisite 20A to disordered intercalated for Cloisite 30B. At an MMT content of 5%, bio-nanocomposite films based on modified MMTs (Cloisite 20A and Cloisite 30B) had better mechanical (tensile strength and percent elongation at break), dynamic mechanical (glass transition temperature and storage modulus), and water barrier properties as compared to those based on natural MMT (Cloisite Na(+)). Bio-nanocomposite films based on 10% Cloisite 30B had mechanical properties comparable to those of some of the plastics that are currently used in food packaging applications. However, much higher WVP values of these films as compared to those of existing plastics might limit the application of these films to packaging of high moisture foods such as fresh fruits and vegetables.

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.

Effect of kaolinite and Ca-montmorillonite on the alleviation of soil water repellency

Czech Academy of Sciences Publication Activity Database

Dlapa, P.; Doerr, S. H.; Lichner, Ľ.; Šír, Miloslav; Tesař, Miroslav

2004-01-01

Roč. 50, č. 8 (2004), s. 358-363 ISSN 0370-663X R&D Projects: GA AV ČR IAA3042301; GA AV ČR IBS2060104 Keywords : water repellency * kaolinite * Ca-montmorillonite Subject RIV: DA - Hydrology ; Limnology Impact factor: 0.379, year: 2004

Reviews of the In-situ Demonstration Test of the Engineered Barrier System in Many Countries

Energy Technology Data Exchange (ETDEWEB)

Lee, Minsoo; Choi, Heui Joo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

Many nations considering the deep geologic disposal of HLW are now planning or executing in-situ demonstration experiments on their regional EBS (Engineering barrier system) at their deep underground research facilities. The main purpose of the in-situ EBS test is the experimental confirmation of its performance, and the prediction of its long-term evolution through the modeling of EBS based on the experimental data. Additionally, the engineering feasibility for the construction of an engineering barrier system can also be checked through full scale construction of an in-situ test. KAERI is currently preparing an in-situ test at a large 1/3 scale, called IN-DEBS (In-situ Demonstration of EBS) at KURT (KAERI Underground Research Tunnel) for the generic EBS suggested in A-KRS (Advanced KAERI Reference System), which was developed to treat the HLW from pyroprocessing. As the first step for the design of IN-DEBS, the foreign in-situ demonstrations of EBS were reviewed in this paper. The demonstration projects, which were completed or are still being executed in some countries such as Sweden, France, Finland, Canada, Belgium, Switzerland, Spain, and Japan, were surveyed and summarized. In particular, hardware constitutions such as the heating element or compact bentonite, and the experimental procedures, have focused more on reviews than on experimental results in this survey, since their hardware information is very important for the design of the IN-DEBS.

Reviews of the In-situ Demonstration Test of the Engineered Barrier System in Many Countries

International Nuclear Information System (INIS)

Lee, Minsoo; Choi, Heui Joo

2013-01-01

Many nations considering the deep geologic disposal of HLW are now planning or executing in-situ demonstration experiments on their regional EBS (Engineering barrier system) at their deep underground research facilities. The main purpose of the in-situ EBS test is the experimental confirmation of its performance, and the prediction of its long-term evolution through the modeling of EBS based on the experimental data. Additionally, the engineering feasibility for the construction of an engineering barrier system can also be checked through full scale construction of an in-situ test. KAERI is currently preparing an in-situ test at a large 1/3 scale, called IN-DEBS (In-situ Demonstration of EBS) at KURT (KAERI Underground Research Tunnel) for the generic EBS suggested in A-KRS (Advanced KAERI Reference System), which was developed to treat the HLW from pyroprocessing. As the first step for the design of IN-DEBS, the foreign in-situ demonstrations of EBS were reviewed in this paper. The demonstration projects, which were completed or are still being executed in some countries such as Sweden, France, Finland, Canada, Belgium, Switzerland, Spain, and Japan, were surveyed and summarized. In particular, hardware constitutions such as the heating element or compact bentonite, and the experimental procedures, have focused more on reviews than on experimental results in this survey, since their hardware information is very important for the design of the IN-DEBS

Barriers and paths to market for genetically engineered crops.

Science.gov (United States)

Rommens, Caius M

2010-02-01

Each year, billions of dollars are invested in efforts to improve crops through genetic engineering (GE). These activities have resulted in a surge of publications and patents on technologies and genes: a momentum in basic research that, unfortunately, is not sustained throughout the subsequent phases of product development. After more than two decades of intensive research, the market for transgenic crops is still dominated by applications of just a handful of methods and genes. This discrepancy between research and development reflects difficulties in understanding and overcoming seven main barriers-to-entry: (1) trait efficacy in the field, (2) critical product concepts, (3) freedom-to-operate, (4) industry support, (5) identity preservation and stewardship, (6) regulatory approval and (7) retail and consumer acceptance. In this review, I describe the various roadblocks to market for transgenic crops and also discuss methods and approaches on how to overcome these, especially in the United States.

Barriers to the clinical translation of orthopedic tissue engineering.

Science.gov (United States)

Evans, Christopher H

2011-12-01

Tissue engineering and regenerative medicine have been the subject of increasingly intensive research for over 20 years, and there is concern in some quarters over the lack of clinically useful products despite the large sums of money invested. This review provides one perspective on orthopedic applications from a biologist working in academia. It is suggested that the delay in clinical application is not atypical of new, biologically based technologies. Some barriers to progress are acknowledged and discussed, but it is also noted that preclinical studies have identified several promising types of cells, scaffolds, and morphogenetic signals, which, although not optimal, are worth advancing toward human trials to establish a bridgehead in the clinic. Although this transitional technology will be replaced by more sophisticated, subsequent systems, it will perform valuable pioneering functions and facilitate the clinical development of the field. Some strategies for achieving this are suggested. © Mary Ann Liebert, Inc.

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

Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

Energy Technology Data Exchange (ETDEWEB)

Hashemi, Mohammed M.; Eftekhari-Sis, Bagher; Khalili, Behzad; Karimi-Jaberi, Zahed [Sharif University of Technology, Tehran (Iran, Islamic Republic of). Dept. of Chemistry]. E-mail: mhashemi@sharif.edu

2005-09-15

Phenols were oxidized to quinones using sodium perborate (SPB) on wet montmorillonite as oxidant. The reaction was carried out at ambient temperature on the solid phase under solvent free conditions. (author)

Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

International Nuclear Information System (INIS)

Hashemi, Mohammed M.; Eftekhari-Sis, Bagher; Khalili, Behzad; Karimi-Jaberi, Zahed

2005-01-01

Phenols were oxidized to quinones using sodium perborate (SPB) on wet montmorillonite as oxidant. The reaction was carried out at ambient temperature on the solid phase under solvent free conditions. (author)

Oxygen barrier of multilayer thin films comprised of polysaccharides and clay.

Science.gov (United States)

Laufer, Galina; Kirkland, Christopher; Cain, Amanda A; Grunlan, Jaime C

2013-06-05

Multilayered thin films of chitosan (CH), carrageenan (CR) and montmorillonite (MMT) clay, deposited using the layer-by-layer technique, were studied in an effort to produce fully renewable polysaccharide-based thin films with low oxygen permeability. Ten 'trilayers' of CH/MMT/CR (film reduced its oxygen permeability (1.76×10(-15) cm(3) cm/cm(2) s Pa) by an order of magnitude under dry conditions. By adding an additional layer of CH to the trilayer sequence, a 'quadlayer' film of CH/CR/CH/MMT (barrier is believed to be due to the unique nanostructure of these films, often referred to as a "nanobrick wall" structure, as well as a strong association amongst the oppositely charged polysaccharides. Combining fully renewable and food contact approved ingredients with high gas barrier and optical transparency makes this technology promising as a foil replacement for food packaging. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

Study on the saturating and swelling behavior of an engineering bentonite barrier using a test model

International Nuclear Information System (INIS)

Nakajima, Makoto; Kobayashi, Ichizo; Toida, Masaru; Fujisaki, Katsutoshi

2007-01-01

The conceptual design of a disposal facility with additional buffer depth for radioactive waste is mainly constituted from the multi-barrier system that is constructed around the waste form so that it prevents radionuclide transfer to the biosphere. The engineered bentonite barrier is one of the elements of the multi-barrier system and is constructed with homogeneous bentonite-containing material compacted to a high density so that there are no voids. Due to the swelling characteristics of the bentonite material, the self-sealing function which is an important function of the bentonite barrier can work, but at the same time it mechanically affects the neighboring structures. Therefore, an experimental study was implemented in order to evaluate the mechanical effect of the bentonite swelling behavior throughout the construction, emplacement operations and closure re-saturation phase. In this article, the results of swelling tests to obtain the mechanical properties of the bentonite and three types of test model experiments performed for the event observations in the different saturation processes are described. As a result, the effects of a seepage pattern of ground water and a variation in the density produced by construction on the swelling pressure distribution of the bentonite barrier could be reproduced and validated. It is thought that they will be important events when ground water permeates the bentonite layer of a multiple barrier system. (author)

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.

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.

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

Characterization of synthesized polyurethane/montmorillonite nanocomposites foams

International Nuclear Information System (INIS)

Ansari, Farahnaz; Njuguna, James; Sachse, Sophia; Kavosh, Masoud; Michalowski, S; Pielichowski, Krzysztof

2014-01-01

Nanophased hybrid composites based on polyurethane/montmorillonite (PU/MMT) have been fabricated. The nanocomposite which was formed by the addition of a polyol premix with 4,4'-diphenylmethane diisocyanate to obtain nanophased polyurethane foams which were then used for fabrication of nanocomposite panels has been shown to have raised strength, stiffness and thermal insulation properties. The nanophased polyurethane foam was characterized by means of scanning electron microscope (SEM), transmission electron microscope (TEM) measurements and X-ray diffraction (XRD). TEM and SEM analysis indicated that nanophased particles are dispersed homogeneously in the polyurethane matrix on the nanometer scale indicating that PU/MMT is an intercalated nanocomposite with a 2-3 nm nanolayer thickness

Barriers and strategies for the clinical translation of advanced orthopaedic tissue engineering protocols.

Science.gov (United States)

Madry, H; Alini, M; Stoddart, M J; Evans, C; Miclau, T; Steiner, S

2014-05-06

Research in orthopaedic tissue engineering has intensified over the last decade and new protocols continue to emerge. The clinical translation of these new applications, however, remains associated with a number of obstacles. This report highlights the major issues that impede the clinical translation of advanced tissue engineering concepts, discusses strategies to overcome these barriers, and examines the need to increase incentives for translational strategies. The statements are based on presentations and discussions held at the AO Foundation-sponsored symposium "Where Science meets Clinics 2013" held at the Congress Center in Davos, Switzerland, in September, 2013. The event organisers convened a diverse group of over one hundred stakeholders involved in clinical translation of orthopaedic tissue engineering, including scientists, clinicians, healthcare industry professionals and regulatory agency representatives. A major point that emerged from the discussions was that there continues to be a critical need for early trans-disciplinary communication and collaboration in the development and execution of research approaches. Equally importantly was the need to address the shortage of sustained funding programs for multidisciplinary teams conducting translational research. Such detailed discussions between experts contribute towards the development of a roadmap to more successfully advance the clinical translation of novel tissue engineering concepts and ultimately improve patient care in orthopaedic and trauma surgery.

Barriers and strategies for the clinical translation of advanced orthopaedic tissue engineering protocols

Directory of Open Access Journals (Sweden)

H Madry

2014-05-01

Full Text Available Research in orthopaedic tissue engineering has intensified over the last decade and new protocols continue to emerge. The clinical translation of these new applications, however, remains associated with a number of obstacles. This report highlights the major issues that impede the clinical translation of advanced tissue engineering concepts, discusses strategies to overcome these barriers, and examines the need to increase incentives for translational strategies. The statements are based on presentations and discussions held at the AO Foundation-sponsored symposium "Where Science meets Clinics 2013" held at the Congress Center in Davos, Switzerland, in September, 2013. The event organisers convened a diverse group of over one hundred stakeholders involved in clinical translation of orthopaedic tissue engineering, including scientists, clinicians, healthcare industry professionals and regulatory agency representatives. A major point that emerged from the discussions was that there continues to be a critical need for early trans-disciplinary communication and collaboration in the development and execution of research approaches. Equally importantly was the need to address the shortage of sustained funding programs for multidisciplinary teams conducting translational research. Such detailed discussions between experts contribute towards the development of a roadmap to more successfully advance the clinical translation of novel tissue engineering concepts and ultimately improve patient care in orthopaedic and trauma surgery.

Study on chemical buffering property of GMZ sodium bentonite under atmospheric condition

International Nuclear Information System (INIS)

Wen Zhijian

2012-01-01

At present, the deep geological disposal is regarded as the most reasonable and effective way to safely disposal the high-level radioactive wastes in the world. The conceptual model of HLW geological disposal in China is based on a multi-barrier system that combines an isolating geological environment with an engineered barrier system. The buffer is one of the engineered barrier materials and GMZ Na-bentonite is selected as the basic material. One of the most important functions related to buffer is the chemical buffering, which means buffering the changes in pore water chemistry. This paper presents the experiments of GMZ-1 Na-bentonite reacted with distilled water under atmospheric condition. The batch tests and results discussion are reported. Na and Mg in batch test solution are co-provided by interlayer cations of montmorillonite and solids dissolution, K and Ca are provided by dissolution of solids. The result is a pre-requisite for predicting near-field nuclide migration and assesses the long-term stability of the engineered barrier materials. (author)

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)

Synthesis and utilization of poly (methylmethacrylate) nanocomposites based on modified montmorillonite

OpenAIRE

Youssef, Ahmed M.; Malhat, F.M.; Abdel Hakim, A.A.; Dekany, Imre

2015-01-01

Poly (methylmethacrylate) nanocomposite was prepared via in-situ emulsion polymerization (PMMA/Mt-CTA). The modified montmorillonite (Mt-CTA) is used as hosts for the preparation of poly (methylmethacrylate) nanocomposites with basal distance 1.95 nm. Moreover, exfoliated nanocomposite was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). The fashioned nanocomposites exhibited bett...

Enhanced photocatalytic activity of microwave treated TiO2 pillared montmorillonite

International Nuclear Information System (INIS)

Sun Shenmei; Jiang Yinshan; Yu Lixin; Li Fangfei; Yang Zhengwen; Hou Tianyi; Hu Daqiang; Xia Maosheng

2006-01-01

TiO 2 pillared montmorillonite synthesized by microwave irradiation, exhibited good photocatalytic degradation performance of methyl orange, whose pseudo first order reaction rate constant was nearly four times than that of conventional method, because of its enhanced crystalline, preferred anatase phase and improved porosity performance, which were analysed by X-ray diffraction (XRD), far Fourier transform infrared ray spectroscopy (FTIR) and nitrogen adsorption isotherms

Geophysical characterization of subsurface barriers

International Nuclear Information System (INIS)

Borns, D.J.

1995-08-01

An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier

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.

Properties and Semicrystalline Structure Evolution of Polypropylene/Montmorillonite Nanocomposites under Mechanical Load

DEFF Research Database (Denmark)

Stribeck, Norbert; Zeinolebadi, Ahmad; Ganjaee Sari, Morteza

2012-01-01

Small-angle X-ray scattering (SAXS) monitors tensile and load-cycling tests of metallocene isotactic polypropylene (PP), a blend of PP and montmorillonite (MMT), and two block copolymer compatibilized PP/MMT nanocomposites. Mechanical properties of the materials are similar, but the semicrystalline......%. Other results concern the evolution of Strobl’s block structure and void formation during tensile loading....

Engineered barrier systems and canister orientation studies for the Yucca Mountain Project, Nevada

International Nuclear Information System (INIS)

Wilder, D.G.

1990-07-01

Emplacement borehole orientation directly impacts many aspects of the Engineered Barrier System (EBS) and interactions with the near field environment. This paper considers the impacts of orientation on the hydrologic portion of the environment and its interactions with the EBS. The hydrologic environments is considered from a conceptual standpoint, the numerical analyses are left for subsequent work. As reported in this paper, several aspects of the hydrological environment are more favorable for long term performance of vertically oriented rather than horizontally oriented Waste Packages. 19 refs., 15 figs

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

Women Engineers: Factors and Obstacles Related to the Pursuit of a Degree in Engineering

Science.gov (United States)

Wentling, Rose Mary; Camacho, Cristina

Research on women in engineering confirms the presence of gender barriers that affect the recruitment and retention of women in engineering. These barriers stop some women from choosing engineering as a field of study, and impede some women from completing a degree in engineering. However, there are some young female students who complete their engineering education despite the presence of obstacles throughout their college years. This study addressed the factors that have hindered, motivated, and assisted women who graduated with a degree in engineering. By studying and understanding the barriers that hinder women in deciding to pursue and in completing a degree in engineering, as well as the factors that assist and encourage them, we can learn how to break down the barriers and how to facilitate the educational journey of female engineering students. This study provides valuable insights and created a framework from which high schools, universities, researchers, and female students can directly benefit.

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)

Loadings in thermal barrier coatings of jet engine turbine blades an experimental research and numerical modeling

CERN Document Server

Sadowski, Tomasz

2016-01-01

This book discusses complex loadings of turbine blades and protective layer Thermal Barrier Coating (TBC), under real working airplane jet conditions. They obey both multi-axial mechanical loading and sudden temperature variation during starting and landing of the airplanes. In particular, two types of blades are analyzed: stationary and rotating, which are widely applied in turbine engines produced by airplane factories.

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.

Clays in natural and engineered barriers for radioactive waste confinement - 4. International meeting. Book of abstracts

International Nuclear Information System (INIS)

2010-01-01

The 4. edition of the International Meeting 'Clays in Natural and Engineered Barriers for Radioactive Waste Confinement' took place at the 'Cite Internationale des Congres' of Nantes (France). Approximately 500 participants (from about 20 different countries) attended the meeting. All the abstracts (oral and poster sessions) are included in these proceedings. The purpose of this 4. international conference is to gather specialists in the different disciplines related to clays and clay minerals, with scientists from organisations engaged in radioactive waste disposal, in order to evaluate the progress of the research conducted in that field. Multidisciplinary approaches including geology, mineralogy, geochemistry, rheology, geomechanics of clays are required in order to provide a detailed characterisation of the geological host formations considered for the disposal of radioactive waste and to assess the behaviour of engineered and natural barriers when submitted to various types of perturbations induced by disposal facilities. The major objectives for the experimental programs are constituted by the performance evaluation for the natural barrier as well as the impact of repository-induced disturbances upon the confinement properties of clay-rich geological formations. This is being or will be conducted in underground research laboratories, for interpreting the subsequent scientific results, for modelling the long-term behaviour of radioactive waste repositories and for carrying out safety assessment exercises. This conference covers all the aspects of clay characterisation and behaviour relevant to the confinement of radionuclides in clay, considered at various time scales and locations, from the descriptions of basic phenomenological processes to the global understanding of the performance and safety at repository and geological scales. Most of the topics covered by the programme of the conference are in line with the general objectives

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

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...

Changes in suspension properties of structural modified montmorillonites Mudanças em propriedades de suspensões de montmorilonitas modificadas estruturalmente

Directory of Open Access Journals (Sweden)

C. Volzone

2001-03-01

Full Text Available Rheological changes were found in smectite (Wyoming- and Cheto-type montmorillonites suspensions after structural modifications. The effect of the particle size and Na+ exchange on the flow curves of 6% wt/wt suspensions of smectites with and without Na2CO3 were examined. Mineralogical, structural and physicochemical characteristics were studied by X-ray diffraction (XRD, infrared spectroscopy (IR, cationic exchange capacity (CEC, Mg2+, Al3+ determinations, particle size distribution and swelling index (SI. Grinding in an oscillating mill modified the particle sizes. The montmorillonite grain size and the structural disorder increased after larger grinding times. The grinding treatment modified the apparent viscosity and the yield stress of the montmorillonite suspensions. The homoionic Na Cheto-type montmorillonite with fine particle size (obtained by grinding increased the flow properties. Nevertheless, rheological properties were lower than those of suspensions of the Wyoming-type montmorillonite. Montmorillonite-types reacted differently with Na2CO3 additions and this behavior may be related to their structural composition. The Na2CO3 activation improved the flow properties of the original Wyoming-type montmorillonite and after 30 s grinding.Foram encontradas mudanças reológicas em suspensões de esmectitas (montmorillonitas tipos Wyoming e Cheto após modificações estruturais. Foi examinado o efeito do tamanho de partícula e troca de Na+ nas curvas de escoamento de suspensões de esmectitas 6% peso com e sem Na2CO3. As características mineralógicas, estructurais e físico-químicas foram estudadas por difração de raios X (DRX, espectroscopia no infravermelho (IV, capacidade de troca catiônica (CTC, determinações de Mg2+ e Al3+, de distribuição de tamanho de partículas e de índice de expansão (swelling index - SI. Moagem em moinho oscilatório modificou o tamanho das partículas. O tamanho de grão da montmorillonita e a

Physicochemical and Geotechnical Alterations to MX-80 Bentonite at the Waste Canister Interface in an Engineered Barrier System

Directory of Open Access Journals (Sweden)

Christopher W. Davies

2017-08-01

Full Text Available The study investigated the basic geomechanical and mineralogical evolution of the bentonite barrier under various experimental boundary conditions which replicated the near-field Thermo-Hydro-Chemico (THC conditions in a repository. The relationships between the physicochemical alterations and changes in the geotechnical properties have seldom been studied, especially on a consistent dataset. This paper attempts to link the physicochemical properties of Na-bentonite (MX-80 to the macro-scale engineering functionality of the bentonite post THC exposure. Experiments investigated the impact of THC variables on the engineering and physicochemical functionality of the bentonite with respect to its application within a High-Level Waste (HLW engineered barrier system. Intrinsic alterations to the MX-80 bentonite under relatively short-term exposure to hydrothermal and chemical conditions were measured. Additionally, two long-term tests were conducted under ambient conditions to consider the impact of exposure duration. The intrinsic measurements were then related to the overall performance of the bentonite as a candidate barrier material for application in a UK geological disposal facility. Findings indicate that exposure to thermo-saline-corrosion conditions (i.e., corrosion products derived from structural grade 275 carbon steel inhibits the free swell capacity and plasticity of the bentonite. However, the measured values remained above the design limits set out for the Swedish multi-barrier concept, from which the UK concept may take a lead. Corrosion alone does not appear to significantly affect the geotechnical measurements compared with the influence of thermal loading and high saline pore water after relatively short-term exposure. Thermal and corrosion exposure displayed no impact on the intrinsic swelling of the smectite component, indicating that no significant structural alteration had occurred. However, when exploring more complex saline

Summary report of research on evaluation of coupled thermo-hydro-mechanical behavior in the engineered barrier

International Nuclear Information System (INIS)

Chijimatsu, Masakazu; Amemiya, Kiyoshi; Yamashita, Ryo

2002-02-01

After emplacement of the engineered barrier system (EBS), it is expected that the near-field environment will be impacted by phenomena such as heat dissipation by conduction and other heat transfer mechanisms, infiltration of groundwater from the surrounding rock in to the engineered barrier system, stress imposed by the overburden pressure and generation of swelling pressure in the buffer due to water infiltration. In order to recognize and evaluate these coupled thermo-hydro-mechanical (THM) phenomena, it is necessary to make a confidence of the mathematical models and computer codes. Evaluating these coupled THM phenomena is important in order to clarify the initial transient behavior of the EBS within the near field. DECOVALEX project is an international co-operative project for the DEvelopment of COupled models and their VALidation against EXperiments in nuclear waste isolation and it is significance to participate this project and to apply the code for the validation. Therefore, we tried to apply the developed numerical code against the subjects of DECOVALEX. In the above numerical code, swelling phenomenon is modeled as the function of water potential. However it dose no evaluate the experiment results enough. Then, we try to apply the new model. (author)

The Effects of Fire on the Function of the 200-BP-1 Engineered Surface Barrier

Energy Technology Data Exchange (ETDEWEB)

Ward, Anderson L.; Link, Steven O.; Hasan, Nazmul; Draper, Kathryn E.

2009-09-01

A critical unknown in use of barrier technology for long-term waste isolation is performance after a major disturbance especially when institutional controls are intact, but there are no resources to implement corrective actions. The objective of this study was to quantify the effects of wild fire on alterations the function of an engineered barrier. A controlled burn September 26, 2008 was used to remove all the vegetation from the north side of the barrier. Flame heights exceeded 9 m and temperatures ranged from 250 oC at 1.5 cm below the surface to over 700 oC at 1 m above the surface. Post-fire analysis of soil properties show significant decreases in wettability, hydraulic conductivity, air entry pressure, organic matter, and porosity relative to pre-fire conditions whereas dry bulk density increased. Decreases in hydraulic conductivity and wettabilty immediately after the fire are implicated in a surface runoff event that occurred in January 2009, the first in 13 years. There was a significant increase in macro-nutrients, pH, and electrical conductivity. After one year, hydrophobicity has returned to pre-burn levels with only 16% of samples still showing signs of decreased wettability. Over the same period, hydraulic conductivity and air entry pressure returned to pre-burn levels at one third of the locations but remained identical to values recorded immediately after the fire at the other two thirds. Soil nutrients, pH, and electrical conductivity remain elevated after 1 year. Species composition on the burned surface changed markedly from prior years and relative to the unburned surface and two analog sites. An increase in the proportion of annuals and biennials is characteristic of burned surfaces that have become dominated by ruderal species. Greenhouse seedling emergence tests conducted to assess the seed bank of pre- and post-burn soils and of two analog sites at the McGee Ranch show no difference in the number of species emerging from soils collected

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.

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

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

Nano porous Adsorbent from Chitosan Interacted Montmorillonite for Dye-containing Wastewater Treatment

International Nuclear Information System (INIS)

Siriphannon, P.; Monvisade, P.

2011-01-01

Chitosan intercalated montmorillonite (Chi-MMT) was prepared by mixing 2 wt% of chitosan solution with sodium mont-morillonite (Na + -MMT) suspension at 60 degree Celsius for 24 hours. The Na + ions in Na + -MMT were completely exchanged with -NH 3 + ions of chitosan, resulting in the intercalation of chitosan into the MMT layer. The chitosan intercalation brought about the expansion of d 001 of Na + -MMT from 1.23 nm to 1.42 - >2.21 nm of the Chi-MMT. The existence of the intercalated-chitosan and large pore size could significantly increase the adsorption capacity of Chi-MMT from those of the starting materials, for example Na + -MMT and chitosan. The adsorption capacity of Chi-MMT adsorbent was equal to 4.9 mg/ g for acid red 91 (AR91) with initial dye concentration of 50 mg/ L, 45.9 mg/ g for basic yellow 1 (BY1) and 15.0 mg/ g for reactive orange 16 (RO16) with initial dye concentration of 500 mg/ L. These results indicated the competency of Chi-MMT nano porous adsorbent for treatment of wastewater containing various kinds of dyestuffs. (author)

PREPARATION AND CHARACTERIZATION OF SOY PROTEIN ISOLATE(SPI)/MONTMORILLONITE(MMT) BIONANOCOMPOSITES

Institute of Scientific and Technical Information of China (English)

傅强

2009-01-01

The bionanocomposites of soy protein isolate(SPI)/montmorillonite(MMT) have been prepared successfully via simple melt mixing,in which MMT was used as nanofiller and glycerol was used as plasticizer.Their structures and properties were characterized with X-ray diffraction(XRD),differential scanning calorimetry(DSC),scanning electron microscopy(SEM),thermogravimetric analysis and tensile testing.XRD、TEM and SEM results indicated that the MMT layers could be easily intercalated by the SPI matrix even by si...

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.

Evaluation of Subsurface Engineered Barriers at Waste Sites

National Research Council Canada - National Science Library

1998-01-01

.... Environmental Protection Agency's (EPA) waste programs with a national retrospective analysis of barrier field performance, and information that may be useful in developing guidance on the use and evaluation of barrier systems...

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...

Natural analogue studies of engineered barrier materials at PNC Tokai, Japan

International Nuclear Information System (INIS)

Kamei, G.; Yusa, Y.; Yamagata, J.; Inoue, K.

1991-01-01

Long-term extrapolations concerning the safety of a nuclear waste repository cannot be satisfactorily made on the sole basis of short-term laboratory tests. Natural analogues, which are the only means by which very slow mechanisms can be identified and by which long-term predictions of models can be tested for pertinence. Our natural analogue studies for the assessment of long-term durability of engineered barrier materials are outlined. Materials of young age and with simple history are the most suitable for the studies as: 1) properties of the materials tend to deteriorate over the longer term; and 2) detailed quantitative data on the term and on the environmental conditions can be obtained. The framework of our studies includes: 1) clarification of alteration phenomena, 2) examination of the environmental conditions, and 3) support experiments. (author)

Sorption/Desorption Interactions of Plutonium with Montmorillonite

Science.gov (United States)

Begg, J.; Zavarin, M.; Zhao, P.; Kersting, A. B.

2012-12-01

Plutonium (Pu) release to the environment through nuclear weapon development and the nuclear fuel cycle is an unfortunate legacy of the nuclear age. In part due to public health concerns over the risk of Pu contamination of drinking water, predicting the behavior of Pu in both surface and sub-surface water is a topic of continued interest. Typically it was assumed that Pu mobility in groundwater would be severely restricted, as laboratory adsorption studies commonly show that naturally occurring minerals can effectively remove plutonium from solution. However, evidence for the transport of Pu over significant distances at field sites highlights a relative lack of understanding of the fundamental processes controlling plutonium behavior in natural systems. At several field locations, enhanced mobility is due to Pu association with colloidal particles that serve to increase the transport of sorbed contaminants (Kersting et al., 1999; Santschi et al., 2002, Novikov et al., 2006). The ability for mineral colloids to transport Pu is in part controlled by its oxidation state and the rate of plutonium adsorption to, and desorption from, the mineral surface. Previously we have investigated the adsorption affinity of Pu for montmorillonite colloids, finding affinities to be similar over a wide range of Pu concentrations. In the present study we examine the stability of adsorbed Pu on the mineral surface. Pu(IV) at an initial concentration of 10-10 M was pre-equilibrated with montmorillonite in a background electrolyte at pH values of 4, 6 and 8. Following equilibration, aliquots of the suspensions were placed in a flow cell and Pu-free background electrolyte at the relevant pH was passed through the system. Flow rates were varied in order to investigate the kinetics of desorption and hence gain a mechanistic understanding of the desorption process. The flow cell experiments demonstrate that desorption of Pu from the montmorillonite surface cannot be modeled as a simple

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.

Combined Effects of JP-8 Fuel and Ceramic Thermal Barrier Coatings on the Performance and Emissions of a DI Diesel Engine

National Research Council Canada - National Science Library

Klett, David

1999-01-01

.... The experiments were conducted on a Ricardo Hydra single-cylinder DI diesel engine. Thin ceramic thermal barrier coatings were applied to various combustion chamber surfaces including the piston crown, cylinder head, and cylinder liner...

Adsorption and degradation of model volatile organic compounds by a combined titania-montmorillonite-silica photocatalyst

International Nuclear Information System (INIS)

Chen Jiangyao; Li Guiying; He Zhigui; An Taicheng

2011-01-01

Highlights: → Adsorptive combined titania-montmorillonite-silica photocatalysts synthesized. → All catalysts had relatively high adsorption capacities of multinary VOCs. → All catalysts preferred to adsorb the VOCs with higher polarity. → CTMS80 can effectively photocatalytically remove VOCs of various components. - Abstract: A series of adsorptive photocatalysts, combined titania-montmorillonite-silica were synthesized. The resultant photocatalysts consisted of more and more spherically agglomerated TiO 2 particles with increasing of TiO 2 content, and anatase was the only crystalline phase with nano-scale TiO 2 particles. With increasing of the cation exchange capacity to TiO 2 molar ratio, specific surface area and pore volume increased very slightly. In a fluidized bed photocatalytic reactor by choosing toluene, ethyl acetate and ethanethiol as model pollutants, all catalysts had relatively high adsorption capacities and preferred to adsorb higher polarity pollutants. Langmuir isotherm model better described equilibrium data compared to Freundlich model. Competitive adsorptions were observed for the mixed pollutants on the catalysts, leading to decrease adsorption capacity for each pollutant. The combined titania-montmorillonite-silica photocatalyst exhibited excellent photocatalytic removal ability to model pollutants of various components. Almost 100% of degradation efficiency was achieved within 120 min for each pollutant with about 500 ppb initial concentration, though the efficiencies of multi-component compounds slightly decreased. All photocatalytic reactions followed the Langmuir-Hinshelwood model. Degradation rate constants of multi-component systems were lower than those for single systems, following the order of toluene < ethyl acetate < ethanethiol, and increased with the increase of adsorption capacities for different pollutants of various components.

Modeling the Hydrogeochemical Transport of Radionuclides through Engineered Barriers System in the Proposed LLW Disposal Site of Taiwan - 12082

Energy Technology Data Exchange (ETDEWEB)

Lin, Wen-Sheng [Hydrotech Research Institute, National Taiwan University, Taipei, Taiwan (China); Liu, Chen-Wuing; Tsao, Jui-Hsuan [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, Taiwan (China); Li, Ming-Hsu [Institute of Hydrological and Oceanic Sciences, National Central University, Jhongli, Taiwan (China)

2012-07-01

A proposed site for final disposal of low-level radioactive waste located in Daren Township of Taitung County along the southeastern coast has been on the selected list in Taiwan. The geology of the Daren site consists of argillite and meta-sedimentary rocks. A mined cavern design with a tunnel system of 500 m below the surface is proposed. Concrete is used as the main confinement material for the engineered barrier. To investigate the hydrogeochemical transport of radionuclides through engineered barriers system, HYDROGEOCHEM5.0 model was applied to simulate the complex chemical interactions among radionuclides, the cement minerals of the concrete, groundwater flow, and transport in the proposed site. The simulation results showed that the engineered barriers system with the side ditch efficiently drained the ground water and lowered the concentration of the concrete degradation induced species (e.g., hydrogen ion, sulfate, and chloride). The velocity of groundwater observed at side ditch gradually decreased with time due to the fouling of pore space by the mineral formation of ettringite and thaumasite. The short half-life of Co-60, Sr-90 and Cs-137 significantly reduced the concentrations, whereas the long half-life of I-129(1.57x10{sup 7} years) and Am-241(432 years) remain stable concentrations at the interface of waste canister and concrete barrier after 300 years. The mineral saturation index (SI) was much less than zero due to the low aqueous concentration of radionuclide, so that the precipitation formation of Co-60, Sr-90, I-129, Cs-137 and Am-241 related minerals were not found. The effect of adsorption/desorption (i.e., surface complexation model) could be a crucial geochemical mechanism for the modeling of liquid-solid phase behavior of radionuclide in geochemically dynamic environments. Moreover, the development of advanced numerical models that are coupled with hydrogeochemical transport and dose assessment of radionuclide is required in the future

The evaluation of the effects of buffer thickness and dry density on radionuclides migration in engineered barrier system

International Nuclear Information System (INIS)

Kato, Fujitaka; Ishihara, Yoshinao; Makino, Hitoshi; Ishiguro, Katsuhiko

2000-01-01

The evaluation of the effects of buffer thickness and dry density, one of the buffer design, on radionuclides migration behavior is important from the viewpoint of performance assessment since they have relation to radionuclides migration retardation. It is also considered to help investigation of buffer design that satisfy both safety and economy to condition of the disposal site, which may be required with development of disposal project in the future. Therefore we have performed a sensitivity analysis used buffer thickness and dry density as parameter and considered their combination in this report. Based on this, we have evaluated the effects of buffer thickness and dry density on radionuclides migration in engineered barrier system. And, we have considered about radionuclides migration retardation quality of the buffer which is based on the design (relationship between thickness and dry density) set in the second progress report on research and development for the geological disposal of HLW in Japan. In results, the maximum release rates from the engineered barrier system for the nuclides which have high distribution coefficients and short half lives are sensitive to changes in buffer thickness and dry density. And, using dose converted from the nuclide release rates from the engineered barrier system as a convenient index, it is almost shown that the maximum of total dose is less than 10 μ Sv/y in the cases which buffer thickness and dry density are based on the buffer design set in the second progress report on research and development for the geological disposal of HLW in Japan. These can be used as an information when design of buffer thickness and dry density is set by synthetically judgement of balance of safety and economy. (author)

PERFORMANCE ANALYSIS OF 1,4 DIOXANE-ETHANOL-DIESEL BLENDS ON DIESEL ENGINES WITH AND WITHOUT THERMAL BARRIER COATING

Directory of Open Access Journals (Sweden)

Chockalingam Sundar Raj

2010-01-01

Full Text Available 1,4 dioxane, a new additive allows the splash blending of ethanol in diesel in a clear solution. The objective of this investigation is to first create a stable ethanol-diesel blended fuel with 10% 1,4 dioxane additive, and then to generate performance, combustion and emissions data for evaluation of different ethanol content on a single cylinder diesel engine with and without thermal barrier coating. Results show improved performance with blends compared to neat fuel for all conditions of the engine. Drastic reduction in smoke density is found with the blends as compared to neat diesel and the reduction is still better for coated engine. NOx emissions were found to be high for coated engines than the normal engine for the blends. The oxygen enriched fuel increases the peak pressure and rate of pressure rise with increase in ethanol ratio and is still superior for coated engine. Heat release pattern shows higher premixed combustion rate with the blends. Longer ignition delay and shorter combustion duration are found with all blends than neat diesel fuel.

Electrochemical and radiochemical material transport examinations in humate-containing montmorillonite a bentonite thin layers

International Nuclear Information System (INIS)

Antal, K.; Joo, P.

1999-01-01

Various humate-containing H-bentonite layers were investigated using 137 Cs ion transport and radio absorption measuring method. These processes can model radioactive contamination migration in soils exposed to acid rains. Experiment using montmorillonite and bentonite layers are discussed, and the results obtained with electrochemical and radioisotope absorption techniques are presented. (R.P.)

Chitosan-Intercalated Montmorillonite/Poly(vinyl alcohol) Nanofibers as a Platform to Guide Neuronlike Differentiation of Human Dental Pulp Stem Cells.

Science.gov (United States)

Ghasemi Hamidabadi, Hatef; Rezvani, Zahra; Nazm Bojnordi, Maryam; Shirinzadeh, Haji; Seifalian, Alexander M; Joghataei, Mohammad Taghi; Razaghpour, Mojgan; Alibakhshi, Abbas; Yazdanpanah, Abolfazl; Salimi, Maryam; Mozafari, Masoud; Urbanska, Aleksandra M; Reis, Rui L; Kundu, Subhas C; Gholipourmalekabadi, Mazaher

2017-04-05

In this study, we present a novel chitosan-intercalated montmorillonite/poly(vinyl alcohol) (OMMT/PVA) nanofibrous mesh as a microenvironment for guiding differentiation of human dental pulp stem cells (hDPSCs) toward neuronlike cells. The OMMT was prepared through ion exchange reaction between the montmorillonite (MMT) and chitosan. The PVA solutions containing various concentrations of OMMT were electrospun to form 3D OMMT-PVA nanofibrous meshes. The biomechanical and biological characteristics of the nanofibrous meshes were evaluated by ATR-FTIR, XRD, SEM, MTT, and LDH specific activity, contact angle, and DAPI staining. They were carried out for mechanical properties, overall viability, and toxicity of the cells. The hDPSCs were seeded on the prepared scaffolds and induced with neuronal specific differentiation media at two differentiation stages (2 days at preinduction stage and 6 days at induction stage). The neural differentiation of the cells cultured on the meshes was evaluated by determining the expression of Oct-4, Nestin, NF-M, NF-H, MAP2, and βIII-tubulin in the cells after preinduction, at induction stages by real-time PCR (RT-PCR) and immunostaining. All the synthesized nanofibers exhibited a homogeneous morphology with a favorable mechanical behavior. The population of the cells differentiated into neuronlike cells in all the experimental groups was significantly higher than that in control group. The expression level of the neuronal specific markers in the cells cultured on 5% OMMT/PVA meshes was significantly higher than the other groups. This study demonstrates the feasibility of the OMMT/PVA artificial nerve graft cultured with hDPSCs for regeneration of damaged neural tissues. These fabricated matrices may have a potential in neural tissue engineering applications.

Disposal systems evaluations and tool development : Engineered Barrier System (EBS) evaluation.

Energy Technology Data Exchange (ETDEWEB)

Rutqvist, Jonny (LBNL); Liu, Hui-Hai (LBNL); Steefel, Carl I. (LBNL); Serrano de Caro, M. A. (LLNL); Caporuscio, Florie Andre (LANL); Birkholzer, Jens T. (LBNL); Blink, James A. (LLNL); Sutton, Mark A. (LLNL); Xu, Hongwu (LANL); Buscheck, Thomas A. (LLNL); Levy, Schon S. (LANL); Tsang, Chin-Fu (LBNL); Sonnenthal, Eric (LBNL); Halsey, William G. (LLNL); Jove-Colon, Carlos F.; Wolery, Thomas J. (LLNL)

2011-01-01

Key components of the nuclear fuel cycle are short-term storage and long-term disposal of nuclear waste. The latter encompasses the immobilization of used nuclear fuel (UNF) and radioactive waste streams generated by various phases of the nuclear fuel cycle, and the safe and permanent disposition of these waste forms in geological repository environments. The engineered barrier system (EBS) plays a very important role in the long-term isolation of nuclear waste in geological repository environments. EBS concepts and their interactions with the natural barrier are inherently important to the long-term performance assessment of the safety case where nuclear waste disposition needs to be evaluated for time periods of up to one million years. Making the safety case needed in the decision-making process for the recommendation and the eventual embracement of a disposal system concept requires a multi-faceted integration of knowledge and evidence-gathering to demonstrate the required confidence level in a deep geological disposal site and to evaluate long-term repository performance. The focus of this report is the following: (1) Evaluation of EBS in long-term disposal systems in deep geologic environments with emphasis on the multi-barrier concept; (2) Evaluation of key parameters in the characterization of EBS performance; (3) Identification of key knowledge gaps and uncertainties; and (4) Evaluation of tools and modeling approaches for EBS processes and performance. The above topics will be evaluated through the analysis of the following: (1) Overview of EBS concepts for various NW disposal systems; (2) Natural and man-made analogs, room chemistry, hydrochemistry of deep subsurface environments, and EBS material stability in near-field environments; (3) Reactive Transport and Coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes in EBS; and (4) Thermal analysis toolkit, metallic barrier degradation mode survey, and development of a Disposal Systems

Disposal systems evaluations and tool development: Engineered Barrier System (EBS) evaluation

International Nuclear Information System (INIS)

Rutqvist, Jonny; Liu, Hui-Hai; Steefel, Carl I.; Serrano de Caro, M.A.; Caporuscio, Florie Andre; Birkholzer, Jens T.; Blink, James A.; Sutton, Mark A.; Xu, Hongwu; Buscheck, Thomas A.; Levy, Schon S.; Tsang, Chin-Fu; Sonnenthal, Eric; Halsey, William G.; Jove-Colon, Carlos F.; Wolery, Thomas J.

2011-01-01

Key components of the nuclear fuel cycle are short-term storage and long-term disposal of nuclear waste. The latter encompasses the immobilization of used nuclear fuel (UNF) and radioactive waste streams generated by various phases of the nuclear fuel cycle, and the safe and permanent disposition of these waste forms in geological repository environments. The engineered barrier system (EBS) plays a very important role in the long-term isolation of nuclear waste in geological repository environments. EBS concepts and their interactions with the natural barrier are inherently important to the long-term performance assessment of the safety case where nuclear waste disposition needs to be evaluated for time periods of up to one million years. Making the safety case needed in the decision-making process for the recommendation and the eventual embracement of a disposal system concept requires a multi-faceted integration of knowledge and evidence-gathering to demonstrate the required confidence level in a deep geological disposal site and to evaluate long-term repository performance. The focus of this report is the following: (1) Evaluation of EBS in long-term disposal systems in deep geologic environments with emphasis on the multi-barrier concept; (2) Evaluation of key parameters in the characterization of EBS performance; (3) Identification of key knowledge gaps and uncertainties; and (4) Evaluation of tools and modeling approaches for EBS processes and performance. The above topics will be evaluated through the analysis of the following: (1) Overview of EBS concepts for various NW disposal systems; (2) Natural and man-made analogs, room chemistry, hydrochemistry of deep subsurface environments, and EBS material stability in near-field environments; (3) Reactive Transport and Coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes in EBS; and (4) Thermal analysis toolkit, metallic barrier degradation mode survey, and development of a Disposal Systems

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

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

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.

Heterogeneous reactions of dioctahedral smectites in illite-smectite and kaolinite-smectite mixed-layers: applications to clay materials for engineered barriers

International Nuclear Information System (INIS)

Meunier, A.; Proust, D.; Beaufort, D.; Lajudie, A.; Petit, J.-C.

1992-01-01

The clay materials selected for use in the engineered barriers of the French nuclear waste isolation programme are mainly composed of dioctahedral smectite, either bentonite of Wyoming type or kaolinite-smectites most often consist of randomly stacked layers with low and high charges. In the case of the Wyoming-type bentonite, these two differently charged layers do not react in the same way when subjected to hydrothermal alteration. Overall, the low-charge smectite layers react to form high-charge smectite layers + quartz + kaolinite. Then, fixing K ions, the high-charge smectite layers are transformed into illite-smectite mixed-layers (I/S) when the temperature conditions increase. A symmetrical process is observed in natural or experimental hydrothermal conditions when the high-charge smectite layers of I/S minerals react with quartz and/or kaolinite to produce low-charge smectite layers. The chemical properties of the bentonite-engineered barriers clearly depend on the low charge/high charge smectite layer proportion, which is in turn controlled by the temperature-dependent reactions in the vicinity of the waste disposal. Although there are fewer published data on the kaolinite-smectite mixed-layered minerals (K/S), a similar low charge-high charge reaction appears to affect their smectite component. The experimental alteration of K/S leads to the formation of a low-charge beidellite with an increase in the cation-exchange capacity and in the expandability of the clay material. Thus, the properties of the engineered barrier seems to be improved after hydrothermal alteration. (Author)

Diffusion and sorption of neptunium(V) in compacted montmorillonite: effects of carbonate and salinity

International Nuclear Information System (INIS)

Tachi, Y.; Yotsuji, K.; Suyama, T.; Seida, Y.; Yui, M.; Nakazawa, T.; Yamada, N.; Ochs, M.

2010-01-01

Diffusion and sorption of radionuclides in compacted bentonite/montmorillonite are key processes in the safe geological disposal of radioactive waste. In this study, the effects of carbonate and salinity on neptunium(V) diffusion and sorption in compacted sodium montmorillonite were investigated by experimental and modeling approaches. Effective diffusion coefficients (D e ) and distribution coefficients (K d ) of 237 Np(V) in sodium montmorillonite compacted to a dry density of 800 kg m -3 were measured under four chemical conditions with different salinities (0.05/0.5 M NaCl) and carbonate concentrations (0.0.01 M NaHCO 3 ). D e values for carbonate-free conditions were of the order of 10 -10 -10 -11 m 2 s -1 and decreased as salinity increased, and those for carbonate conditions were of the order of 10 -11 -10 -12 m 2 s -1 and showed the opposite dependence. Diffusion-derived K d values for carbonate-free conditions were higher by one order of magnitude than those for carbonate conditions. Diffusion and sorption behaviors were interpreted based on mechanistic models by coupling thermodynamic aqueous speciation, thermodynamic sorption model (TSM) based on ion exchange, and surface complexation reactions, and a diffusion model based on electrical double layer (EDL) theory in homogeneous narrow pores. The model predicted the experimentally observed tendency of D e and K d qualitatively, as a result of the following mechanisms; 1) the dominant aqueous species are NpO 2 + and NpO 2 CO 3 - for carbonate-free and carbonate conditions, respectively, 2) the effects of cation excess and anion exclusion result in opposite tendencies of D e for salinity, 3) higher carbonate in solution inhibits sorption due to the formation of carbonate complexes. (orig.)

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...

Appliance of geochemical engineering in radioactive waste disposal

International Nuclear Information System (INIS)

Li Shuang; Zhang Chengjiang; Ni Shijun; Li Kuanliang

2008-01-01

The basic foundation of applying geochemical engineering to control environment, common engineering models of disposal radioactive waste and the functions of the engineering barriers are introduced in this paper. The authors take the geochemical engineering barrier materiel research of a radioactive waste repository as an example to explain the appliance of geochemical engineering in the disposal of radioactive waste. And the results show that it can enhance the security of the nuclear waste repository if we use geochemical engineering barrier. (authors)

Re-engineering therapeutic antibodies for Alzheimer's disease as blood-brain barrier penetrating bi-specific antibodies.

Science.gov (United States)

Pardridge, William M

2016-12-01

Therapeutic antibodies are large molecule drugs that do not cross the blood-brain barrier (BBB). Therefore, drug development of therapeutic antibodies for Alzheimer's disease (AD) requires that these molecules be re-engineered to enable BBB delivery. This is possible by joining the therapeutic antibody with a transporter antibody, resulting in the engineering of a BBB-penetrating bispecific antibody (BSA). Areas covered: The manuscript covers transporter antibodies that cross the BBB via receptor-mediated transport systems on the BBB, such as the insulin receptor or transferrin receptor. Furthermore, it highlights therapeutic antibodies for AD that target the Abeta amyloid peptide, beta secretase-1, or the metabotropic glutamate receptor-1. BSAs are comprised of both the transporter antibody and the therapeutic antibody, as well as IgG constant region, which can induce immune tolerance or trigger transport via Fc receptors. Expert opinion: Multiple types of BSA molecular designs have been used to engineer BBB-penetrating BSAs, which differ in valency and spatial orientation of the transporter and therapeutic domains of the BSA. The plasma pharmacokinetics and dosing regimens of BSAs differ from that of conventional therapeutic antibodies. BBB-penetrating BSAs may be engineered in the future as new treatments of AD, as well as other neural disorders.

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”.

Biomimetic thermal barrier coating in jet engine to resist volcanic ash deposition

Science.gov (United States)

Song, Wenjia; Major, Zsuzsanna; Schulz, Uwe; Muth, Tobias; Lavallée, Yan; Hess, Kai-Uwe; Dingwell, Donald B.

2017-04-01

The threat of volcanic ash to aviation safety is attracting extensive attention when several commercial jet aircraft were damaged after flying through volcanic ash clouds from the May 1980 eruptions of Mount St. Helen in Washington, U.S. and especially after the air traffic disruption in 2010 Eyjafjallajökull eruption. A major hazard presented by volcanic ash to aircraft is linked to the wetting and spreading of molten ash droplets on engine component surfaces. Due to the fact ash has a lower melting point, around 1100 °C, than the gas temperature in the hot section (between 1400 to 2000 °C), this cause the ash to melt and potentially stick to the internal components (e.g., combustor and turbine blades), this cause the ash to melt and potentially stick to the internal components of the engine creating, substantial damage or even engine failure after ingestion. Here, inspiring form the natural surface of lotus leaf (exhibiting extreme water repellency, known as 'lotus effect'), we firstly create the multifunctional surface thermal barrier coatings (TBCs) by producing a hierarchical structure with femtosecond laser pulses. In detail, we investigate the effect of one of primary femtosecond laser irradiation process parameter (scanning speed) on the hydrophobicity of water droplets onto the two kinds of TBCs fabricated by electron-beam physical vapor deposition (EB-PVD) and air plasma spray (APS), respectively as well as their corresponding to morphology. It is found that, comparison with the original surface (without femtosecond laser ablation), all of the irradiated samples demonstrate more significant hydrophobic properties due to nanostructuring. On the basis of these preliminary room-temperature results, the wettability of volcanic ash droplets will be analysed at the high temperature to constrain the potential impact of volcanic ash on the jet engines.

Ion-exchange equilibria and diffusion in engineered backfill

International Nuclear Information System (INIS)

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

1984-01-01

Engineered backfill can add confidence to confinement times of high-level nuclear waste stored in geologic media. This paper discusses the design and operation of a unique radial-flow diffusion cell to determine ion migration rates in backfill material under realistic repository conditions. New experimental results were reported for diffusion of CsCl in a background of NaCl into compacted bentonite and bentonite/quartz mixtures. Representation of the measured diffusion rates by the traditional, homogeneous porous-medium model significantly underestimates cesium penetration distances into the backfill. Surface diffusion is suggested as an additional mechanism by which cations transport in swollen montmorillonite; the surface diffusion coefficients for cesium is determined to be approximately 10 -7 cm 2 /s. An electrostatic site-binding model is developed for ion-exchange equilibria on montmorillonite clay. The effect of pH, ionic strength, and specific adsorption are evaluated and compared favorably to new, experimental exchange isotherms measured on disaggregated clay. The electrostatic site-binding model permits a prediction of the influence of backfill compaction on K/sub d/ values. We find that for strongly adsorbing cations, compactions has little effect. However, anions exhibit significant Donnan exclusion with clay compaction. 40 references, 12 figures

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

Transcytosis in the blood–cerebrospinal fluid barrier of the mouse brain with an engineered receptor/ligand system

Directory of Open Access Journals (Sweden)

Héctor R Méndez-Gómez

Full Text Available Crossing the blood–brain and the blood–cerebrospinal fluid barriers (BCSFB is one of the fundamental challenges in the development of new therapeutic molecules for brain disorders because these barriers prevent entry of most drugs from the blood into the brain. However, some large molecules, like the protein transferrin, cross these barriers using a specific receptor that transports them into the brain. Based on this mechanism, we engineered a receptor/ligand system to overcome the brain barriers by combining the human transferrin receptor with the cohesin domain from Clostridium thermocellum, and we tested the hybrid receptor in the choroid plexus of the mouse brain with a dockerin ligand. By expressing our receptor in choroidal ependymocytes, which are part of the BCSFB, we found that our systemically administrated ligand was able to bind to the receptor and accumulate in ependymocytes, where some of the ligand was transported from the blood side to the brain side.

Temperature effect on the behaviour of engineered clay barriers

International Nuclear Information System (INIS)

Tang, A.M.

2005-11-01

The present work deals with the thermo-hydro-mechanical behaviour of compacted swelling clay used for engineered barriers in high-level radioactive repositories. The MX80 bentonite was chosen for this work. Firstly, an experimental work on the thermal conductivity of the compacted bentonite was performed. The results evidenced the effects of dry density, water content, volumetric fraction of soil components, microstructure, and mineralogy. This experimental work gave rise to the proposition of a theoretical model for estimate the thermal conductivity of compacted bentonites. Secondly, after a calibration of suction generated by saturated saline solution in function of temperature, water retention curves were determined at different temperatures. The experimental results showed a decrease of the water retention capacity of soil after heating. A simple model based on the interfacial tension air-water was formulated to simulate this effect. Thirdly, a new isotropic cell enabling a simultaneous control of suction, temperature and mechanical stress was developed. With this new cell, an experimental work on the thermo-mechanical behaviour of the unsaturated compacted bentonite was performed. Finally, a constitutive model was developed for simulate the thermo-hydro-mechanical behaviours obtained experimentally. (author)

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.

Mechanism of amitriptyline adsorption on Ca-montmorillonite (SAz-2)

Energy Technology Data Exchange (ETDEWEB)

Chang, Po-Hsiang [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); 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); Li, Zhaohui, E-mail: li@uwp.edu [Department of Geosciences, University of Wisconsin – Parkside, 900 Wood Road, Kenosha, WI 53144 (United States); Kuo, Chung-Yih [Department of Public Health, College of Health Care and Management, Chung Shan Medical University, No. 110, Sec. 1, Chien-kuo N Road, Taichung 40242, Taiwan (China); Jean, Jiin-Shuh [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Chen, Wan-Ru [Department of Environmental Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Lv, Guocheng [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China)

2014-07-30

Graphical abstract: XRD patterns to show AMI intercalation into SAz-2 vs. direct mixing of the same amount of AMI with SAz-2. - Highlights: • Ca-montmorillonite is proven to be an efficient adsorbent or sink for amitriptyline. • The high adsorption capacity is accompanied with intercalation into interlayers. • The adsorption is mainly governed by a cation exchange mechanism. • Horizontal mono- and bi-layer conformations occur at low and high adsorption levels. • The process is an endothermic physisorption at high adsorption levels. - Abstract: The uptake of amitriptyline (AMI) from aqueous environment by Ca-montmorillonite (SAz-2) was studied in a batch system under different physicochemical conditions. The adsorbent was characterized by X-ray diffraction and Fourier transform infrared (FTIR) analyses. The AMI adsorption on SAz-2 obeyed the Langmuir isotherm with a capacity of 330 mg/g (1.05 mmol/g) at pH 6–7. The adsorption kinetics was fast, almost reaching equilibrium in 2 h, and followed a pseudo-second-order kinetic model. Desorption of exchangeable cations correlated with the AMI adsorption well, indicating that cation exchange was the major mechanism. X-ray diffraction patterns showing significant expansions of the d{sub 0} {sub 0} {sub 1} spacing and characteristic FTIR band shifts toward higher frequencies after AMI adsorption onto SAz-2 indicated that the adsorbed AMI molecules were intercalated into the interlayers of the mineral. Thermodynamic parameters based on partitioning coefficients suggested that the AMI adsorption was an endothermic physisorption at high adsorption levels. At low and higher AMI adsorption levels, the intercalated AMI molecules take a horizontal monolayer and bilayer conformation, respectively. The higher adsorption capacity suggested that SAz-2 could be a good candidate to remove AMI from wastewater and would be an important environmental sink for the fate and transport of AMI in soils and groundwater.

Mechanism of amitriptyline adsorption on Ca-montmorillonite (SAz-2)

International Nuclear Information System (INIS)

Chang, Po-Hsiang; Jiang, Wei-Teh; Li, Zhaohui; Kuo, Chung-Yih; Jean, Jiin-Shuh; Chen, Wan-Ru; Lv, Guocheng

2014-01-01

Graphical abstract: XRD patterns to show AMI intercalation into SAz-2 vs. direct mixing of the same amount of AMI with SAz-2. - Highlights: • Ca-montmorillonite is proven to be an efficient adsorbent or sink for amitriptyline. • The high adsorption capacity is accompanied with intercalation into interlayers. • The adsorption is mainly governed by a cation exchange mechanism. • Horizontal mono- and bi-layer conformations occur at low and high adsorption levels. • The process is an endothermic physisorption at high adsorption levels. - Abstract: The uptake of amitriptyline (AMI) from aqueous environment by Ca-montmorillonite (SAz-2) was studied in a batch system under different physicochemical conditions. The adsorbent was characterized by X-ray diffraction and Fourier transform infrared (FTIR) analyses. The AMI adsorption on SAz-2 obeyed the Langmuir isotherm with a capacity of 330 mg/g (1.05 mmol/g) at pH 6–7. The adsorption kinetics was fast, almost reaching equilibrium in 2 h, and followed a pseudo-second-order kinetic model. Desorption of exchangeable cations correlated with the AMI adsorption well, indicating that cation exchange was the major mechanism. X-ray diffraction patterns showing significant expansions of the d 0 0 1 spacing and characteristic FTIR band shifts toward higher frequencies after AMI adsorption onto SAz-2 indicated that the adsorbed AMI molecules were intercalated into the interlayers of the mineral. Thermodynamic parameters based on partitioning coefficients suggested that the AMI adsorption was an endothermic physisorption at high adsorption levels. At low and higher AMI adsorption levels, the intercalated AMI molecules take a horizontal monolayer and bilayer conformation, respectively. The higher adsorption capacity suggested that SAz-2 could be a good candidate to remove AMI from wastewater and would be an important environmental sink for the fate and transport of AMI in soils and groundwater

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.

Improved Barriers to Turbine Engine Fragments: Final Annual Report

National Research Council Canada - National Science Library

Shockey, Donald

2002-01-01

.... Previous large-scale fragment impact testing of comer peg-mounted fabric barriers indicated that the failure of the fabric around the pegged hole was a significant factor in the barrier's effectiveness...

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

Aerospace Ceramic Materials: Thermal, Environmental Barrier Coatings and SiC/SiC Ceramic Matrix Composites for Turbine Engine Applications

Science.gov (United States)

Zhu, Dongming

2018-01-01

Ceramic materials play increasingly important roles in aerospace applications because ceramics have unique properties, including high temperature capability, high stiffness and strengths, excellent oxidation and corrosion resistance. Ceramic materials also generally have lower densities as compared to metallic materials, making them excellent candidates for light-weight hot-section components of aircraft turbine engines, rocket exhaust nozzles, and thermal protection systems for space vehicles when they are being used for high-temperature and ultra-high temperature ceramics applications. Ceramic matrix composites (CMCs), including non-oxide and oxide CMCs, are also recently being incorporated in gas turbine engines for high pressure and high temperature section components and exhaust nozzles. However, the complexity and variability of aerospace ceramic processing methods, compositions and microstructures, the relatively low fracture toughness of the ceramic materials, still remain the challenging factors for ceramic component design, validation, life prediction, and thus broader applications. This ceramic material section paper presents an overview of aerospace ceramic materials and their characteristics. A particular emphasis has been placed on high technology level (TRL) enabling ceramic systems, that is, turbine engine thermal and environmental barrier coating systems and non-oxide type SiC/SiC CMCs. The current status and future trend of thermal and environmental barrier coatings and SiC/SiC CMC development and applications are described.

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

The field migration tests of 237Np, 238Pu, 241Am and 90Sr in aerated loess, aquifer and engineering barrier materials

International Nuclear Information System (INIS)

Li Shushen; Wang Zhiming; Zhao Yingjie; Fan Zhiwen; Liu Chunli; An Yongfeng; Yang Yue'e; Wu Qinghua

2003-01-01

This paper introduces the field migration tests of 237 Np, 238 Pu, 241 Am and 90 Sr in aerated loess, aquifer and engineering barrier materials. The tests in the aerated loess and engineering barrier materials were carried out under both natural and artificial sprinkling (15 mm/d) conditions. The tests in aquifer were carried out in both assemblies packed with undisturbed aquifer media and a definite undisturbed area. The results indicate that after 3 years tests no significant migrations were seen for all nuclides in engineering barrier materials under two kinds of conditions and in aerated loess under natural conditions. For the aerated loess under artificial sprinkling conditions, 2.7 cm (center of mass) migration in the area directly below the sand tracer layer (named as area 1) and 13 cm (peak) migration in the area outside the area 1 for 90 Sr were observed; There was no migration for 237 Np, 238 Pu and 241 Am. It was discovered that the sand layer used as carrier of nuclide tracer has barrier effect on unsaturated water and an influence on nuclide migration. This has been demonstrated by the inter comparison experiment with both sand and loess as tracer carrier. In the tracer tests of undisturbed aquifer area there was no significant migration of 237 Np, 238 Pu, 241 Am and 90 Sr after 1023 days. In the assembly 8 there was no significant migration for 238 Pu and 241 Am and a small backward migration 0.95 cm for 237 Np and 4.7 cm migration (center of mass) for 90 Sr were observed. The tests also indicate that there is no significant difference of nuclide migration in ordinary and degraded cement

Effects of thermal barrier coating on gas emissions and performance of a LHR engine with different injection timings and valve adjustments

International Nuclear Information System (INIS)

Bueyuekkaya, Ekrem; Engin, Tahsin; Cerit, Muhammet

2006-01-01

Tests were performed on a six cylinder, direct injection, turbocharged Diesel engine whose pistons were coated with a 350 μm thickness of MgZrO 3 over a 150 μm thickness of NiCrAl bond coat. CaZrO 3 was employed as the coating material for the cylinder head and valves. The working conditions for the standard engine (uncovered) and low heat rejection (LHR) engine were kept exactly the same to ensure a realistic comparison between the two configurations of the engine. Comparisons between the standard engine and its LHR version were made based on engine performance, exhaust gas emissions, injection timing and valve adjustment. The results showed that 1-8% reduction in brake specific fuel consumption could be achieved by the combined effect of the thermal barrier coating (TBC) and injection timing. On the other hand, NO x emissions were obtained below those of the base engine by 11% for 18 o BTDC injection timing

Facile synthesis of high strength hot-water wood extract films with oxygen-barrier performance

Science.gov (United States)

Chen, Ge-Gu; Fu, Gen-Que; Wang, Xiao-Jun; Gong, Xiao-Dong; Niu, Ya-Shuai; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

2017-01-01

Biobased nanocomposite films for food packaging with high mechanical strength and good oxygen-barrier performance were developed using a hot-water wood extract (HWE). In this work, a facile approach to produce HWE/montmorillonite (MMT) based nanocomposite films with excellent physical properties is described. The focus of this study was to determine the effects of the MMT content on the structure and mechanical properties of nanocomposites and the effects of carboxymethyl cellulose (CMC) on the physical properties of the HWE-MMT films. The experimental results suggested that the intercalation of HWE and CMC in montmorillonite could produce compact, robust films with a nacre-like structure and multifunctional characteristics. This results of this study showed that the mechanical properties of the film designated FCMC0.05 (91.5 MPa) were dramatically enhanced because the proportion of HWE, MMT and CMC was 1:1.5:0.05. In addition, the optimized films exhibited an oxygen permeability below 2.0 cm3 μm/day·m2·kPa, as well as good thermal stability due to the small amount of CMC. These results provide a comprehensive understanding for further development of high-performance nanocomposites which are based on natural polymers (HWE) and assembled layered clays (MMT). These films offer great potential in the field of sustainable packaging.

Study of Cesium and Strontium sorption in Brazilian clays for their use as a barrier in repositories of radioactive wastes

International Nuclear Information System (INIS)

Freire, Carolina Braccini

2007-01-01

Wastes in general should be properly treated and stored. Then the radioactive wastes also require suitable and safe management beginning in their generation until the storage in repository. The main purpose of the radioactive waste management is to preserve the human beings and the environment. The objective of this research was to characterize some Brazilian clays in order to evaluate the viability of their use in the backfill layer, one of the radioactive waste repository barriers. The main function of this barrier is to contribute in the delay of the radionuclides movement, and to prevent their release into the environment. Four clays provided by national suppliers were selected for the research: Ca-Montmorillonite (Dol 01), Na-Montmorillonite (Dol 02), Kaolinite (Ind 01) and Vermiculite (Ubm 04). Their physical, chemical and mineralogical characteristics were determined, and also their sorption potential of Cesium and Strontium cations. It was confirmed through these results a direct relationship among their specific surface (SS), the capacity of cationic exchange (CCE) and pH. The CCE results followed this increasing order: Ind 01, Dol 01, and Dol 02. In accordance with the models of Freundlich (KJ) and Langmuir (M), the clays Dol 01 and Dol 02 were the best sorbers of Sr 2+ . The Ind 01 and Ubm 04 were the best ones in the case of Cs + . The Gibbs free energy change (ΔG deg) was calculated for the sorption reactions between the clays and the cations, and it was negative for all clays, confirming the sorption reaction spontaneity. (author)

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)

Characterization of cement paste as engineered barrier of borehole repository

International Nuclear Information System (INIS)

Ferreira, Eduardo G.A.; Isiki, Vera L. K.; Miyamoto, Hissae; Marumo, Julio T.; Vicente, Roberto

2009-01-01

Results of axial rupture by compression of cylindrical cement paste samples are presented. This is part of a research on cement paste behavior aiming at investigating the durability of cementitious materials in the environment of repositories for radioactive waste. Portland cement paste is intended to be used as a backfill in a deep borehole for disposal of sealed radiation sources which concept is under development. The service life of the engineered barrier materials plays an important role in the long term safety of such facilities. Accelerated tests in laboratory are being used to evaluate the performance of cement paste under the temperature expected at some hundred meters below grade, under exposure to the radiation emitted by the sources, and under the attack of aggressive chemicals dissolved in the groundwater, during the millennia necessary for the decay of the most active and long-lived radionuclides present in the waste. The large variability in results of mechanical strength as measured by axial compression of cylindrical samples is the subject of this short communication. (author)

A qualitative, interprofessional analysis of barriers to and facilitators of implementation of the Department of Veterans Affairs' Clostridium difficile prevention bundle using a human factors engineering approach.

Science.gov (United States)

Yanke, Eric; Moriarty, Helene; Carayon, Pascale; Safdar, Nasia

2018-03-01

Clostridium difficile infection (CDI) is increasingly prevalent, severe, and costly. Adherence to infection prevention practices remains suboptimal. More effective strategies to implement guidelines and evidence are needed. Interprofessional focus groups consisting of physicians, resident physicians, nurses, and health technicians were conducted for a quality improvement project evaluating adherence to the Department of Veterans Affairs' (VA) nationally mandated C difficile prevention bundle. Qualitative analysis with a visual matrix display identified barrier and facilitator themes guided by the Systems Engineering Initiative for Patient Safety model, a human factors engineering approach. Several themes, encompassing both barriers and facilitators to bundle adherence, emerged. Rapid turnaround time of C difficile polymerase chain reaction testing was a facilitator of timely diagnosis. Too few, poorly located, and cluttered sinks were barriers to appropriate hand hygiene. Patient care workload and the time-consuming process of contact isolation precautions were also barriers to adherence. Multiple work system components serve as barriers to and facilitators of adherence to the VA CDI prevention bundle among an interprofessional group of health care workers. Organizational factors appear to significantly influence bundle adherence. Interprofessional perspectives are needed to identify barriers to and facilitators of bundle implementation, which is a necessary first step to address adherence to bundled infection prevention practices. Published by Elsevier Inc.

Waste form performance assessment in the YUCCA Mountain engineered barrier system, American Nuclear Society

International Nuclear Information System (INIS)

Morris, E. E.; Fanning, T. H.; Wigeland, R. A.

2000-01-01

This work demonstrates a technique for comparing the performance of waste forms in a repository environment when one or more of the waste forms constitute a small part of the total amount of waste planned for the repository. In applying the technique, it is important to identify radionuclides that are highly soluble in the transport fluid since it is only for these that the release is controlled by the dissolution rate of the waste form matrix. The techniques presented here have been applied to an evaluation of the performance of waste forms from the electrometallurgical treatment of spent fuel in the proposed Yucca Mountain Repository Engineered Barrier System (EBS)

Evaluation of Erosion Resistance of Advanced Turbine Thermal Barrier Coatings

Science.gov (United States)

Zhu, Dongming; Kuczmarski, Maria A.; Miller, Robert A.; Cuy, Michael D.

2007-01-01

The erosion resistant turbine thermal barrier coating system is critical to aircraft engine performance and durability. By demonstrating advanced turbine material testing capabilities, we will be able to facilitate the critical turbine coating and subcomponent development and help establish advanced erosion-resistant turbine airfoil thermal barrier coatings design tools. The objective of this work is to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and/or thermal gradient environments, validating advanced turbine airfoil thermal barrier coating systems based on nano-tetragonal phase toughening design approaches.

H, HM, and THM-C processes in engineered barriers

Energy Technology Data Exchange (ETDEWEB)

Cui, Y.J.; Tang, A.M.; Loiseau, C.; Delage, P.; Polak, M.; Souli, H.; Fleureau, J.M.; Wu, P.L.; Tien, Y.M.; Romero, E.; LI, Xiang Ling; Tanaka, Y.; Hasegawa, T.; Nakamura, K.; Sahara, F.; Murakami, T.; Kobayashi, I.; Mihara, M.; Ohi, T.; Lu, J.D.; Huang, W.H.; Lee, W.Y.; Sui, I.H.; Villar, M.V.; Sanchez, M.; Gens, A.; Samper, J.; Lu, C.; Montenegro, L.; Birgersson, M.; Karnland, O.; Nilsson, U.; Akesson, M.; Kristensson, O.; Gatabin, C.; Yang, C.R.; Huang, W.H.; Hsiao, T.H.; Dueck, A.; Lonnqvist, M.; Goudarzi, R.; Borgesson, L.; Fernandez, A.M.; Rivas, P.; Melon, A.M.; Villar, M.V.; Ferrow, E.; Bender Koch, Ch.; Suzuki, S.; Sazarashi, M.; Takegahara, T.; Takao, H.; Tanai, K.; Matsumoto, K.; Gatabin, C.; Touze, G.; Imbert, C.; Guillot, W.; Billaud, P

2007-07-01

This session gathers 24 articles (posters) dealing with: determining water permeability of a compacted bentonite sand mixture under confined and free-swell conditions; the model prediction of engineered barrier system effectiveness in the fracture at laboratory scale; the changes in the hydraulic properties of a smectite in presence of chromium; the wall friction and ejection behaviour of bentonite-base buffer material; the thermo-hydro-mechanical behaviour of a large scale mock-up test 'Ophelie' in Belgium: laboratory characterization and numerical modelling; modeling swelling characteristics and permeability of several compacted bentonite affected by saline water; modelling for the long-term Mechanical and Hydraulic behaviour of bentonite-based materials considering chemical transitions; the coupled thermal-hydro analysis on partially saturated bentonite; the behaviour of a bentonite barrier in the laboratory: experimental results up to 8 years and numerical simulation; a coupled hydrogeochemical calculations of the interactions of corrosion products and bentonite; the freezing in saturated bentonite: a thermodynamic approach; the mechanical modeling of MX-80: Development of constitutive laws; the mechanical modeling of MX-80 - Quick tools for BBM parameter analysis; TBT{sub 3} Mock-up test-experimental and model results; the suction characteristics of two compacted bentonite; the retention curves and volume change properties of unsaturated MX-80 bentonite: a laboratory study; humidity induced swelling and water absorption rate of highly compacted bentonite; unconfined compression tests on bentonite samples exposed to high temperature during long time in the field test lot; the thermophysical properties of bentonite; the geochemistry and mineralogy of a bentonite subjected to heating and hydration in an in-situ test after five years operation; the LOT project, long term test of buffer material at Aespoe: a Moessbauer spectroscopic study; the self

Studying nanostructure gradients in injection-molded polypropylene/montmorillonite composites by microbeam small-angle x-ray scattering

DEFF Research Database (Denmark)

Stribeck, Norbert; Schneider, Konrad; Zeinolebadi, Ahmad

2014-01-01

The core–shell structure in oriented cylindrical rods of polypropylene (PP) and nanoclay composites (NCs) from PP and montmorillonite (MMT) is studied by microbeam small-angle x-ray scattering (SAXS). The structure of neat PP is almost homogeneous across the rod showing regular semicrystalline......-shaped phyllosilicate filler particles....

Armored Geomembrane Cover Engineering

Directory of Open Access Journals (Sweden)

Kevin Foye

2011-06-01

Full Text Available Geomembranes are an important component of modern engineered barriers to prevent the infiltration of stormwater and runoff into contaminated soil and rock as well as waste containment facilities—a function generally described as a geomembrane cover. This paper presents a case history involving a novel implementation of a geomembrane cover system. Due to this novelty, the design engineers needed to assemble from disparate sources the design criteria for the engineering of the cover. This paper discusses the design methodologies assembled by the engineering team. This information will aid engineers designing similar cover systems as well as environmental and public health professionals selecting site improvements that involve infiltration barriers.

Microbiome Remodeling via the Montmorillonite Adsorption-Excretion Axis Prevents Obesity-related Metabolic Disorders

Directory of Open Access Journals (Sweden)

Pengfei Xu

2017-02-01

Full Text Available Obesity and its related metabolic disorders are closely correlated with gut dysbiosis. Montmorillonite is a common medicine used to treat diarrhea. We have previously found that dietary lipid adsorbent-montmorillonite (DLA-M has an unexpected role in preventing obesity. The aim of this study was to further investigate whether DLA-M regulates intestinal absorption and gut microbiota to prevent obesity-related metabolic disorders. Here, we show that DLA-M absorbs free fatty acids (FFA and endotoxins in vitro and in vivo. Moreover, the combination of fluorescent tracer technique and polarized light microscopy showed that DLA-M crystals immobilized BODIPY® FL C16 and FITC-LPS, respectively, in the digestive tract in situ. HFD-fed mice treated with DLA-M showed mild changes in the composition of the gut microbiota, particularly increases in short-chain fatty acids (SCFA-producing Blautia bacteria and decreases in endotoxin-producing Desulfovibrio bacteria, these changes were positively correlated with obesity and inflammation. Our results indicated that DLA-M immobilizes FFA and endotoxins in the digestive tract via the adsorption-excretion axis and DLA-M may potentially be used as a prebiotic to prevent intestinal dysbiosis and obesity-associated metabolic disorders in obese individuals.

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.

Parallax barrier engineering for image quality improvement in an autostereoscopic 3D display.

Science.gov (United States)

Kim, Sung-Kyu; Yoon, Ki-Hyuk; Yoon, Seon Kyu; Ju, Heongkyu

2015-05-18

We present a image quality improvement in a parallax barrier (PB)-based multiview autostereoscopic 3D display system under a real-time tracking of positions of a viewer's eyes. The system presented exploits a parallax barrier engineered to offer significantly improved quality of three-dimensional images for a moving viewer without an eyewear under the dynamic eye tracking. The improved image quality includes enhanced uniformity of image brightness, reduced point crosstalk, and no pseudoscopic effects. We control the relative ratio between two parameters i.e., a pixel size and the aperture of a parallax barrier slit to improve uniformity of image brightness at a viewing zone. The eye tracking that monitors positions of a viewer's eyes enables pixel data control software to turn on only pixels for view images near the viewer's eyes (the other pixels turned off), thus reducing point crosstalk. The eye tracking combined software provides right images for the respective eyes, therefore producing no pseudoscopic effects at its zone boundaries. The viewing zone can be spanned over area larger than the central viewing zone offered by a conventional PB-based multiview autostereoscopic 3D display (no eye tracking). Our 3D display system also provides multiviews for motion parallax under eye tracking. More importantly, we demonstrate substantial reduction of point crosstalk of images at the viewing zone, its level being comparable to that of a commercialized eyewear-assisted 3D display system. The multiview autostereoscopic 3D display presented can greatly resolve the point crosstalk problem, which is one of the critical factors that make it difficult for previous technologies for a multiview autostereoscopic 3D display to replace an eyewear-assisted counterpart.

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.

A two-dimensional magnetic hybrid material based on intercalation of a cationic Prussian blue analog in montmorillonite nanoclay

NARCIS (Netherlands)

Gournis, Dimitrios; Papachristodoulou, Christina; Maccallini, Enrico; Rudolf, Petra; Karakassides, Michael A.; Karamanis, Dimitrios T.; Sage, Marie-Helene; Palstra, Thomas T. M.; Colomer, Jean-Francois; Papavasileiou, Konstantinos D.; Melissas, Vasilios S.; Gangas, Nicolaos H.

2010-01-01

A highly ordered two-dimensional hybrid magnetic nanocomposite has been prepared by synthesizing and intercalating a new cationic aluminum-hydroxy ferric ferrocyanide compound into a cation-adsorbing nanoclay (montmorillonite). Chemical and structural properties were investigated by X-ray

Investigation and technical reviews of the long term stability and corrosion resistance of engineering barriers

International Nuclear Information System (INIS)

Tachikawa, Hirokazu

2004-03-01

The Japan Nuclear Fuel Cycle Development Institute submitted 'Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan' to the Japanese government. This report contains investigations of the long term behavior of alteration of bentonite, and of the corrosion life time of overpack on the basis of experimental data and past research, assuming the ranging geological environment of Japan. However some subjects, such as the behavior of the bentonite and overpack under high pH conditions and the behavior of the engineering barrier with change of near-field environmental condition with time for promoting reliability have still been left. To take into account these conditions, expert committees composed of clay science and metal corrosion science experts were established in the Nuclear Safety Research Association and past research outcomes and the theory of safety assessment were investigated and technically reviewed from the view points of long term stability and corrosion resistance of engineering buffer materials. (author)

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.

Controlling effective aspect ratio and packing of clay with pH for improved gas barrier in nanobrick wall thin films.

Science.gov (United States)

Hagen, David A; Saucier, Lauren; Grunlan, Jaime C

2014-12-24

Polymer-clay thin films constructed via layer-by-layer (LbL) assembly, with a nanobrick wall structure (i.e., clay nanoplatelets as bricks surrounded by a polyelectrolyte mortar), are known to exhibit a high oxygen barrier. Further barrier improvement can be achieved by lowering the pH of the clay suspension in the polyethylenimine (PEI) and montmorillonite (MMT) system. In this case, the charge of the deposited PEI layer is increased in the clay suspension environment, which causes more clay to be deposited. At pH 4, MMT platelets deposit with near perfect ordering, observed with transmission electron microscopy, enabling a 5× improvement in the gas barrier for a 10 PEI/MMT bilayer thin film (85 nm) relative to the same film made with pH 10 MMT. This improved gas barrier approaches that achieved with much higher aspect ratio vermiculite clay. In essence, lower pH is generating a higher effective aspect ratio for MMT due to greater induced surface charge in the PEI layers, which causes heavier clay deposition. These flexible, transparent nanocoatings have a wide range of possible applications, from food and electronics packaging to pressurized bladders.

Engineered Barrier System Thermal-Hydraulic-Chemical Column Test Report

International Nuclear Information System (INIS)

W.E. Lowry

2001-01-01

The Engineered Barrier System (EBS) Thermal-Hydraulic-Chemical (THC) Column Tests provide data needed for model validation. The EBS Degradation, Flow, and Transport Process Modeling Report (PMR) will be based on supporting models for in-drift THC coupled processes, and the in-drift physical and chemical environment. These models describe the complex chemical interaction of EBS materials, including granular materials, with the thermal and hydrologic conditions that will be present in the repository emplacement drifts. Of particular interest are the coupled processes that result in mineral and salt dissolution/precipitation in the EBS environment. Test data are needed for thermal, hydrologic, and geochemical model validation and to support selection of introduced materials (CRWMS M and O 1999c). These column tests evaluated granular crushed tuff as potential invert ballast or backfill material, under accelerated thermal and hydrologic environments. The objectives of the THC column testing are to: (1) Characterize THC coupled processes that could affect performance of EBS components, particularly the magnitude of permeability reduction (increases or decreases), the nature of minerals produced, and chemical fractionation (i.e., concentrative separation of salts and minerals due to boiling-point elevation). (2) Generate data for validating THC predictive models that will support the EBS Degradation, Flow, and Transport PMR, Rev. 01

Study of the Properties of Bentonites for their use in Clay Geo synthetic Barriers

International Nuclear Information System (INIS)

Leiro Lopez, A.; Mateo Sanz, B.; Garcia Cidoncha, H.; Blanco Fernandez, M.

2014-01-01

Bentonites used for the production of clay geo synthetic barriers need to meet some properties so that they can be a waterproofing system. among the bentonites used in industry, sodium bentonite has the lowest permeability due to its high water absorption capacity in the inter-laminar space, causing it to swell and form a barrier to water flow. this paper provides the study of the properties of four bentonite to evaluate their quality the study of the properties of four bentonite to evaluate their quality. For this study, the main properties have been tested: water absorption, swelling index, fluid loss, cation exchange capacity and montmorillonite content. In order to optimize the procedure for the characterization of bentonites, correlations between different tests have been done, to identify the most suitable ones. Finally, a compatibility test has been carried out to study the performance of bentonites in water containing a high amount of sales, because in this case, an ion exchange between the interlayer sodium ions of bentonite and cations dissolved in the water can take, resulting in a decrease swell of the bentonite. (Author)

Adiabatic Wankel type rotary engine

Science.gov (United States)

Kamo, R.; Badgley, P.; Doup, D.

1988-01-01

This SBIR Phase program accomplished the objective of advancing the technology of the Wankel type rotary engine for aircraft applications through the use of adiabatic engine technology. Based on the results of this program, technology is in place to provide a rotor and side and intermediate housings with thermal barrier coatings. A detailed cycle analysis of the NASA 1007R Direct Injection Stratified Charge (DISC) rotary engine was performed which concluded that applying thermal barrier coatings to the rotor should be successful and that it was unlikely that the rotor housing could be successfully run with thermal barrier coatings as the thermal stresses were extensive.

Characterization of polyurethane/organophilic montmorillonite nanocomposites by low field NMR; Caracterizacao de nanocompositos de poliuretano/montmorilonita organofilica por RMN de baixo campo

Energy Technology Data Exchange (ETDEWEB)

Silva, Marcos Anacleto da [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Laboratorio de Nanocompositos Polimericos; Tavares, Maria I.B.; Nascimento, Suelen A.M.; Rodrigues, Elton J. da R [Universidade Federal do Rio de Janeiro (NUCAT/PEQ/COPPE/UFRJ), RJ (Brazil). Laboratorio de Nanocompositos Polimericos

2012-07-01

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)

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 CFR 63.115 - Requirements for multiple barriers.

Science.gov (United States)

2010-01-01

... Requirements for multiple barriers. Demonstration of compliance with § 63.113(a) must: (a) Identify those design features of the engineered barrier system, and natural features of the geologic setting, that are... 10 Energy 2 2010-01-01 2010-01-01 false Requirements for multiple barriers. 63.115 Section 63.115...

Reactive transport predictions for an Olkiluoto. Final repository tunnel unit

International Nuclear Information System (INIS)

Luukkonen, A.; Nordman, H.

2007-09-01

The presented hydrogeochemical reactive transport calculations concentrate to a defined unit piece (unit cell) of the planned Olkiluoto repository that is under design for spent nuclear fuel. The material properties assigned to the tunnel unit are based on literature as far as possible. Calculations make up geochemical future scenarios on the repository evolution. Most recent predictions on the potential future climate at Olkiluoto are utilised together with estimates how future hydraulic conditions affect the repository. Two climate scenarios are considered in detail. The Weichselian-R scenario is based on the repetition of the last glacial cycle, while the Emissions-M scenario attempts to predict the future groundwater conditions at Olkiluoto in the situation where the atmospheric greenhouse gasses delay the next glacial cycle at least for 100,000 years. The groundwater compositions, considered active at the repository depth in future, are judged in this study. Several geochemical processes are considered active at the repository depth. Calculations concentrate on the changes occurring with time within the tunnel unit. All simulations are done in geochemically reducing conditions. It turns out that sulphur cycling in these conditions is in central role considering the safety assessment studies of Olkiluoto repository. Furthermore, groundwater salinity and cation occupancy within the exchange sites of montmorillonite contributes to sealing properties of the engineered barrier system. Calculations attempt to estimate effects of possible future scenarios for the Olkiluoto repository. The results indicate that the buffer capacities assigned to the tunnel unit are large enough, at least to next 100,000 years, to maintain dissolved sulphide contents low in the groundwater infiltrating through the tunnel engineered barrier system. Geochemical reactions raise the bicarbonate levels within the groundwater. This is a useful buffer if low pH conditions emerge in the

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)

Women in Engineering: The Impact of the College Internship on Persistence into an Engineering Field

Science.gov (United States)

Brush, Kimberly M.

2013-01-01

The development of a diverse engineering workforce, with a variety of skills and interests is essential to the future of American innovation. Historically, the engineering field has been grounded in a series of standards that often benefit men while creating barriers for women. Thus, strategies for overcoming barriers to women's successful…

137Cs sorption onto Fullers' Earth (calcium montmorillonite) -the influence of sulphate reducing bacteria

International Nuclear Information System (INIS)

West, J.M.; Haigh, D.G.; Hooker, P.J.; Rowe, E.J.

1987-12-01

The influences of Desulfovibrio desulfuricans on the sorption of 137 Cs onto Fullers' Earth (Calcium montmorillonite) has been studied using batch sorption methods. Results were expressed as distributions ratios (Rd) and as Freundlich and Dubinin-Radushkevich isotherms. They show that microbes present naturally in the Fullers' Earth did not influence sorption data, however the addition of microbes in the aqueous phase alters the sorption properties in a complex manner. (author)

Investigating the Potential Barrier Function of Nanostructured Materials Formed in Engineered Barrier Systems (EBS) Designed for Nuclear Waste Isolation.

Science.gov (United States)

Cuevas, Jaime; Ruiz, Ana Isabel; Fernández, Raúl

2018-02-21

Clay and cement are known nano-colloids originating from natural processes or traditional materials technology. Currently, they are used together as part of the engineered barrier system (EBS) to isolate high-level nuclear waste (HLW) metallic containers in deep geological repositories (DGR). The EBS should prevent radionuclide (RN) migration into the biosphere until the canisters fail, which is not expected for approximately 10 3  years. The interactions of cementitious materials with bentonite swelling clay have been the scope of our research team at the Autonomous University of Madrid (UAM) with participation in several European Union (EU) projects from 1998 up to now. Here, we describe the mineral and chemical nature and microstructure of the alteration rim generated by the contact between concrete and bentonite. Its ability to buffer the surrounding chemical environment may have potential for further protection against RN migration. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fostering Creative Engineers

DEFF Research Database (Denmark)

Zhou, Chunfang

2012-01-01

. As the literature demonstrates, this paper reveals the understanding of complexity in engineering practice and the roles of creativity in engineering practice. In addition, the barriers to creativity in current engineering education and some implications of pedagogic strategies will be discussed. So this paper...

Synthesis of silver nanoparticles in montmorillonite and their antibacterial behavior

Directory of Open Access Journals (Sweden)

Shameli K

2011-03-01

Full Text Available Kamyar Shameli1, Mansor Bin Ahmad1, Mohsen Zargar2, Wan Md Zin Wan Yunus1, Abdolhossein Rustaiyan3, Nor Azowa Ibrahim11Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 2Department of Biology, Faculty of Science, Islamic Azad University, Qom Branch, Qom, Iran; 3Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, IranAbstract: Silver nanoparticles (Ag NPs were synthesized by the chemical reducing method in the external and interlamellar space of montmorillonite (MMT as a solid support at room temperature. AgNO3 and NaBH4 were used as a silver precursor and reducing agent, respectively. The most favorable experimental conditions for synthesizing Ag NPs in the MMT are described in terms of the initial concentration of AgNO3. The interlamellar space limits changed little (d-spacing = 1.24–1.47 nm; therefore, Ag NPs formed on the MMT suspension with d-average = 4.19–8.53 nm diameter. The Ag/MMT nanocomposites (NCs, formed from AgNO3/MMT suspension, were characterizations with different instruments, for example UV-visible, PXRD, TEM, SEM, EDXRF, FT-IR, and ICP-OES analyzer. The antibacterial activity of different sizes of Ag NPs in MMT were investigated against Gram-positive, ie, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA and Gram-negative bacteria, ie, Escherichia coli, Escherichia coli O157:H7, and Klebsiella pneumoniae, by the disk diffusion method using Mueller-Hinton agar (MHA. The smaller Ag NPs were found to have significantly higher antibacterial activity. These results showed that Ag NPs can be used as effective growth inhibitors in different biological systems, making them applicable to medical applications.Keywords: silver nanoparticles, nanoparticles, montmorillonite, antibacterial activity, Mueller-Hinton agar 

Near-field geologic environment as an effective barrier against radionuclide transport

International Nuclear Information System (INIS)

Umeki, H.; Sakuma, H.; Ishiguro, K.; Hatanaka, K.; Naito, M.

1993-01-01

A generic performance assessment of the geologic disposal system of HLW in Japan has been carried out by the Power Reactor and Nuclear Fuel Development Corporation (PNC) in accordance with the overall HLW management program defined by the Japanese Atomic Energy Commission. A massive engineered barrier system, consisting of vitrified waste, carbon-steel overpack and thick bentonite buffer, is introduced to ensure a long-term performance of the disposal system considering a wide range of geologic environment. A major part of the total performance of the disposal system is borne by the engineered barrier system given a geologic environment that assures and complements the performance of such engineered barrier system. The performance of the natural barrier system coupled with the strong engineered barrier system was investigated by sensitivity analyses. Two types of conceptual model were considered for the analysis to describe radionuclide transport in geologic media and the range of relevant parameters was given by taking the variation of the geologic environment in Japan into account. The results show that the degree of retardation of radionuclide transport chosen in the geologic media varies significantly depending on the parameter values chosen. However, it is indicated that there are realistic combinations of those geologic parameter values which could provide a sufficient degree of retardation within a range of only a few tens of meters from the engineered barrier system. The relative importance of the near-field geologic environment is also discussed

An easy and effective method for the intercalation of hydrophobic natural dye into organo-montmorillonite for improved photostability

Science.gov (United States)

Taguchi, Taiga; Kohno, Yoshiumi; Shibata, Masashi; Tomita, Yasumasa; Fukuhara, Choji; Maeda, Yasuhisa

2018-05-01

β-carotene (BC) is one of the naturally occurring dyes belonging to the carotenoids group. Although it is more environmentally friendly and better suited for humans compared with synthetic dyes, it destabilizes with light and heat, easily losing its color under irradiation. Extended application of BC are therefore limited. The aim of this study is to improve the stability of BC by intercalation into the montmorillonite layers modified with a cationic surfactant, by a simple mixing and minimal solvent use. The physical mixing of small quantities of concentrated BC/hexane solutions with organo-modified montmorillonite successfully resulted in the composite material. The length and the number of alkyl chains of the surfactant used for the organic modification influenced the stability enhancement of the incorporated dye. The improved stability of the dye molecules incorporated in the interlayer space was found to be due to restricted contact with atmospheric oxygen.

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.

Artificial Intelligence in Numerical Modeling of Silver Nanoparticles Prepared in Montmorillonite Interlayer Space

Directory of Open Access Journals (Sweden)

Parvaneh Shabanzadeh

2013-01-01

Full Text Available Artificial neural network (ANN models have the capacity to eliminate the need for expensive experimental investigation in various areas of manufacturing processes, including the casting methods. An understanding of the interrelationships between input variables is essential for interpreting the sensitivity data and optimizing the design parameters. Silver nanoparticles (Ag-NPs have attracted considerable attention for chemical, physical, and medical applications due to their exceptional properties. The nanocrystal silver was synthesized into an interlamellar space of montmorillonite by using the chemical reduction technique. The method has an advantage of size control which is essential in nanometals synthesis. Silver nanoparticles with nanosize and devoid of aggregation are favorable for several properties. In this investigation, the accuracy of artificial neural network training algorithm was applied in studying the effects of different parameters on the particles, including the AgNO3 concentration, reaction temperature, UV-visible wavelength, and montmorillonite (MMT d-spacing on the prediction of size of silver nanoparticles. Analysis of the variance showed that the AgNO3 concentration and temperature were the most significant factors affecting the size of silver nanoparticles. Using the best performing artificial neural network, the optimum conditions predicted were a concentration of AgNO3 of 1.0 (M, MMT d-spacing of 1.27 nm, reaction temperature of 27°C, and wavelength of 397.50 nm.

Performance of phosphoric acid activated montmorillonite as buffer materials for radioactive waste repository

International Nuclear Information System (INIS)

Wang, Tsing-Hai; Liu, Tsung-Ying; Wu, Ding-Chiang; Li, Ming-Hsu; Chen, Jiann-Ruey; Teng, Shi-Ping

2010-01-01

In this study, the performance of phosphoric acid activated montmorillonite (PAmmt) was evaluated by cesium ions adsorption experiments. The PAmmt samples were obtained by activating with 1, 3 and 5 mol L -1 of phosphoric acid, respectively under reflux for 3, 12, and 24 h. Experimental results demonstrated that the treatment of raw K-10 montmorillonite with phosphoric acid increased the materials' affinity for Cs uptake and no significant amount of suspension solids were produced. A relatively insignificant variation in the CEC value was observed. Furthermore, PAmmt also showed high adsorption selectivity toward Cs ions. The improved sorptive properties were mainly related to the increased surface area and the relatively higher surface charge density. Increased specific surface area was the resulted from partial decomposition of lamellar structure of mmt; while the higher surface charge density was caused by the protonation of octahedral Al-OH sites during the acid activation. Generally speaking, stronger acid concentration and longer activation times would produce relatively more decomposed PAmmt particles. However, as the activation exceeds 3 h, the precipitation of Si 4+ would passivate PAmmt against further acid attacks. Based upon our results, acid activation by phosphoric acid could produce PAmmt samples with high sorption capacity and selectivity, and good structural integrity, which are beneficial to be used at radioactive waste repository.

Prototype Engineered Barrier System Field Tests (PEBSFT)

International Nuclear Information System (INIS)

Ramirez, A.L.; Wilder, D.G.

1991-02-01

This progress report presents the interpretation of data obtained (up to November 1, 1988) from the Prototype Engineered Barrier System Field Tests (PEBSFT) that are being performed for the Yucca Mountain Project (YMP) in G-Tunnel within the Nevada Test site. The PEBSFTs are being conducted to evaluate the applicability of measurement techniques, numerical models, and procedures developed for the field tests for future investigations that will be conducted in the Exploratory Shaft Facilities, at a potential high-level radioactive waste repository site in Yucca Mountain. The primary objective of the tests is to provide the basis for determining whether tests planned for Yucca Mountain have the potential to be successful. Thirteen chapters discuss the following: mapping the electromagnetic permittivity and attenuation rate of the rock mass; changes in moisture content detected by the neutron logging probe; characterization of the in-situ permeability of the fractured tuff around the heater borehole; electrical resistance heater installed in a 30-cm borehole; relative humidity measurements; the operation, design, construction, calibration, and installation of a microwave circuit that might provide partial pressure information at temperatures in excess of 200 degree C (392 degree F); pressure and temperature measurements in the G-Tunnel; the moisture collection system, which attempts to collect steam that migrates into the heater borehole; The borehole television and borescope surveys that were performed to map the location, orientation, and aperture of the fractures intersecting the boreholes; preliminary scoping calculations of the hydrothermal conditions expected for this prototype test; the Data Acquisition System; and the results of the PEBSFT, preliminary interpretations of these results, and plans for the remainder of the test. Chapters have been indexed separately for inclusion on the data base

Prototype Engineered Barrier System Field Test (PEBSFT)

International Nuclear Information System (INIS)

Ramirez, A.L.; Buscheck, T.; Carlson, R.; Daily, W.; Lee, K.; Lin, Wunan; Mao, Nai-hsien; Ueng, Tzou-Shin; Wang, H.; Watwood, D.

1991-08-01

This final report represents a summary of data and interpretations obtained from the Prototype Engineered Barrier System Field Test (PEBSFT) performed in G-Tunnel within the Nevada Test Site. The PEBSFT was conducted to evaluate the applicability of measurement techniques, numerical models, and procedures developed for future field tests that will be conducted in the Exploratory Studies Facilities (ESF) at Yucca Mountain. The primary objective of the test was to provide a basis for determining whether tests planned for the ESF have the potential to be successful. Chapter 1 on high frequency electromagnetic tomography discusses the rock mass electromagnetic permittivity and attenuation rate changes that were measured to characterize the water distribution in the near field of a simulated waste container. The data are used to obtain quantitative estimates of how the moisture content in the rock mass changes during heating and to infer properties of the spatial variability of water distribution, leading to conclusions about the role of fractures in the system. Chapter 2 discusses the changes in rock moisture content detected by the neutron logging probe. Chapter 3 permeability tests discusses the characterization of the in-situ permeability of the fractured tuff around the borehole. The air permeability testing apparatus, the testing procedures, and the data analysis are presented. Chapter 4 describes the moisture collection system installed in the heater borehole to trap and measure the moisture volumes. Chapter 5 describes relative humidity measurements made with the thermocouple psychrometer and capacitance sensors. Chapter 6 discusses gas pressure measurements in the G-Tunnel, addressing the calibration and installation of piezoresistive-gaged transducers. Chapter 7 describes the calibration and installation of thermocouples for temperature measurements. Chapter 8 discusses the results of the PEBSFT

The Development of Environmental Barrier Coatings for SiCSiC Ceramic Matrix Composites: Challenges and Opportunities

Science.gov (United States)

Zhu, Dongming

2014-01-01

Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is a key to enable the applications of the envisioned CMC components to help achieve next generation engine performance and durability goals. This paper will primarily address the performance requirements and design considerations of environmental barrier coatings for turbine engine applications. The emphasis is placed on current candidate environmental barrier coating systems for SiCSiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing advanced environmental barrier coating systems, the coating integrations with next generation CMC turbine components having improved environmental stability, cyclic durability and system performance will be described. The development trends for turbine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be discussed.

Study on the basic property of Gaomiaozi bentonite, inner mongolia

International Nuclear Information System (INIS)

Liu Yuemiao; Xu Guoqing; Liu Shufen; Chen Zhangru

2001-01-01

Buffer/backfill material layer is one of important engineered barriers in the HLW geological repository. The geologic setting of Gaomiaozi bentonite deposit is introduced, and the mineral composition, physical and chemical property, basic geotechnical property, swelling property and permeability of highly compacted bentonite of main ore bed has been studied. The study results show that montmorillonite content of Gaomiaozi bentonite is relatively high, physical and chemical property, geotechnical property and impermeability are good. So Gaomiaozi bentonite deposit could be regarded as supply base of buffer/backfill material for HLW geological repository

Sorption and direct speciation of neptunium(V) on aluminium oxide and montmorillonite

International Nuclear Information System (INIS)

Wendt, Sonja

2009-01-01

This study comprised batch experiments, direct speciation studies via EXAFS, and modelling with the 2SPNE SC/CE model to elucidate the mechanisms of Np(V) sorption on montmorillonite and, for reference, on γ-Al 2 O 3 . The sorption of pM 239 Np(V) and μM 237 Np(V) on montmorillonite (STx-1, 4 g/L) and γ-Al 2 O 3 (0.5 g/L) was studied at room temperature in the presence and absence of ambient CO 2 covering a pH-range from 2.5 (STx-1) or 5 (γ-Al 2 O 3 ) to 10.5 with 0.01 or 0.1M NaClO 4 as background electrolyte. The Np(V) uptake was determined by γ spectroscopy of the supernatants and calculated as percentage as well as distribution coefficient K d . Sorption starts from pH ∼6 and, under exclusion of CO 2 , increases continuously, while, in the presence of ambient air, it reaches a maximum at pH ∝8.5 (γ-Al 2 O 3 : logK d max ∼ 4 mL/g; STx-1: logK d max ∼ 2.7 mL/g). Beyond that it decreases again due to the formation of aqueous neptunium carbonate complexes. Furthermore, neptunium sorption on montmorillonite is influenced by ionic strength at pH <6 through ion exchange processes pointing towards the formation of outer-sphere surface complexes there. Isotherms measured at the sorption maximum showed the precipitation of presumably neptunium carbonate complexes above 3.10 -5 M under ambient air conditions. Additionally, they indicated progressive saturation of the sorption sites of γ-Al 2 O 3 . At selected pH (STx-1: 5.0, 7.0, 8.0, 8.5, 9.0, 9.5; γ-Al 2 O 3 : 8.5, 9.5) EXAFS samples were prepared as wet pastes with μM 237 Np and measured at room temperature in fluorescence mode at ANKA and ESRF. Several spectra were averaged and analysed with EXAFSPAK and FEFF 8.20 employing models of NaNpO 2 (CO 3 ) or soddyite, (UO 2 ) 2 SiO 4 .2(H 2 O). The shorter atomic distances of the neptunyl ion at pH 5 compared to the others hinted at the retention of the hydration shell and, thus, at outer-sphere sorption. On average the bond lengths for Np(V) sorbed on STx

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)

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

Development of backfill material as an engineered barrier in the waste package system. Interim topical report

International Nuclear Information System (INIS)

Wheelwright, E.J.; Hodges, F.N.; Bray, L.A.; Westsik, J.H. Jr.; Lester, D.H.; Nakai, T.L.; Spaeth, M.E.; Stula, R.T.

1981-09-01

A backfill barrier, emplaced between the containerized waste and the host rock, can both protect the other engineered barriers and act as a primary barrier to the release of radionuclides from the waste package. Attributes that a backfill should provide in order to carry out its required function have been identified. Primary attributes are those that have a direct effect upon the release and transport of radionuclides from the waste package. Supportive attributes do not directly affect radionuclide release but are necessary to support the primary attributes. The primary attributes, in order of importance, are: minimize (retard or exclude) the migration of ground water between the host rock and the waste canister system; retard the migration of selected chemical species (corrosive species and radionuclides) in the ground water; control the Eh and pH of the ground water within the waste-package environment. The supportive attributes are: self-seal any cracks or discontinuities in the backfill or interfacing host geology; retain performance properties at all repository temperatures; retain peformance properties during and after receiving repository levels of gamma radiation; conduct heat from the canister system to the host geology; retain mechanical properties and provide resistance to applied mechanical forces; retain morphological stability and compatibility with structural barriers and with the host geology for required period of time. Screening and selection of candidate backfill materials has resulted in a preliminary list of materials for testing. Primary emphasis has been placed on sodium and calcium bentonites and zeolites used in conjunction with quartz sand or crushed host rock. Preliminary laboratory studies have concentrated on permeability, sorption, swelling pressure, and compaction properties of candidate backfill materials

Sensitivity of performance assessment of the engineered barriers to nuances of release rate criteria

International Nuclear Information System (INIS)

Oliver, D.L.R.

1987-01-01

The United States Nuclear Regulatory Commission (NRC) has established criteria for the long-term performance of proposed high-level waste repositories. As with any regulation, the criteria may be interpreted in several ways. Due to the high capital costs and the emotional political climate associated with any high-level radioactive waste repository, it is important that there be an early consensus regarding interpretations of the criteria, and what assumptions may be used to demonstrate compliance with them. This work uses analytic solutions of mass transport theory to demonstrate how sensitive performance analyses are to various nuances of the NRC release rate criterion for the engineered barriers. The analysis is directed at the proposed repository in basalt at the Hanford site in Washington State

Technology CAD of silicided Schottky barrier MOSFET for elevated source-drain engineering

International Nuclear Information System (INIS)

Saha, A.R.; Chattopadhyay, S.; Bose, C.; Maiti, C.K.

2005-01-01

Technology CAD has been used to study the performance of a silicided Schottky barrier (SB) MOSFET with gate, source and drain contacts realized with nickel-silicide. Elevated source-drain structures have been used towards the S/D engineering of CMOS devices. A full process-to-device simulation has been employed to predict the performance of sub-micron SB n-MOSFETs for the first time. A model for the diffusion and alloy growth kinetics has been incorporated in SILVACO-ATLAS and ATHENA to explore the processing and design parameter space for the Ni-silicided MOSFETs. The temperature and concentration dependent diffusion model for NiSi have been developed and necessary material parameters for nickel-silicide and epitaxial-Si have been incorporated through the C-interpreter function. Two-dimensional (2D) process-to-device simulations have also been used to study the dc and ac (RF) performance of silicided Schottky barrier (SB) n-MOSFETs. The extracted sheet resistivity, as a function of annealing temperature of the silicided S/D contacts, is found to be lower than the conventional contacts currently in use. It is also shown that the Technology CAD has the full capability to predict the possible dc and ac performance enhancement of a MOSFET with elevated S/D structures. While the simulated dc performance shows a clear enhancement, the RF analyses show no performance degradation in the cut-off frequency/propagation delay and also improve the ac performance due to the incorporation of silicide contacts in the S/D region

Technology CAD of silicided Schottky barrier MOSFET for elevated source-drain engineering

Energy Technology Data Exchange (ETDEWEB)

Saha, A.R. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India)]. E-mail: ars.iitkgp@gmail.com; Chattopadhyay, S. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India); School of Electrical, Electronics and Computer Engineering, University of Newcastle, Newcastle upon Tyne (United Kingdom); Bose, C. [Department of Electronics and Telecommunication Engineering, Jadavpur University, Calcutta 700032 (India); Maiti, C.K. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India)

2005-12-05

Technology CAD has been used to study the performance of a silicided Schottky barrier (SB) MOSFET with gate, source and drain contacts realized with nickel-silicide. Elevated source-drain structures have been used towards the S/D engineering of CMOS devices. A full process-to-device simulation has been employed to predict the performance of sub-micron SB n-MOSFETs for the first time. A model for the diffusion and alloy growth kinetics has been incorporated in SILVACO-ATLAS and ATHENA to explore the processing and design parameter space for the Ni-silicided MOSFETs. The temperature and concentration dependent diffusion model for NiSi have been developed and necessary material parameters for nickel-silicide and epitaxial-Si have been incorporated through the C-interpreter function. Two-dimensional (2D) process-to-device simulations have also been used to study the dc and ac (RF) performance of silicided Schottky barrier (SB) n-MOSFETs. The extracted sheet resistivity, as a function of annealing temperature of the silicided S/D contacts, is found to be lower than the conventional contacts currently in use. It is also shown that the Technology CAD has the full capability to predict the possible dc and ac performance enhancement of a MOSFET with elevated S/D structures. While the simulated dc performance shows a clear enhancement, the RF analyses show no performance degradation in the cut-off frequency/propagation delay and also improve the ac performance due to the incorporation of silicide contacts in the S/D region.

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.

Analysis on the use of engineered barriers for geologic isolation of spent fuel in a reference salt site repository

International Nuclear Information System (INIS)

Cloninger, M.O.; Cole, C.R.; Washburn, J.F.

1980-12-01

A perspective on the potential durability and effectiveness requirements for the waste form, container and other engineered barriers for geologic disposal of spent nuclear fuel has been developed. This perspective is based on calculated potential doses to individuals who may be exposed to radioactivity released from a repository via a groundwater transport pathway. These potential dose commitments were calculated with an integrated geosphere transport and bioshpere transport model. A sensitivity analysis was accomplished by varying four important system parameters, namely the waste radionuclide release rate from the repository, the delay prior to groundwater contact with the waste (leach initiation), aquifer flow velocity and flow path length. The nuclide retarding capacity of the geologic media, a major determinant of the isolation effectiveness, was not varied as a parameter but was held constant for a particular reference site. This analysis is limited to looking only at engineered barriers whose net effect is either to delay groundwater contact with the waste form or to limit the rate of release of radionuclides into the groundwater once contact has occurred. The analysis considers only leach incident scenarios, including a water well intrusion into the groundwater near a repository, but does not consider other human intrusion events or catastrophic events. The analysis has so far been applied to a reference salt site repository system and conclusions are presented.Basically, in nearly all cases, the regional geology is the most effective barrier to release of radionuclides to the biosphere; however, for long-lived isotopes of carbon, technetium and iodine, which were poorly sorbed on the geologic media, the geology is not very effective once a leach incident is initiated

International conference on the performance of engineered barriers. Physical and chemical properties, behaviour and evolution. Short abstracts

Energy Technology Data Exchange (ETDEWEB)

Schaefers, Annika; Fahland, Sandra (eds.)

2014-08-01

The volume includes the abstracts of the papers presented at the international conference on the performance of engineered barrier systems, their physical and chemical properties, behavior and evolution. The papers cover the topics bentonite buffers, radioactive waste repository safety, geophysical and geochemical property monitoring, repository sealing materials, thermo-hydro-mechanical characterization, gas injection tests, hydration and heating tests, clay-iron interaction experiments, water retention behavior, thermal stability of materials, numerical modeling studies, long-term simulations, thermo-hydrologic phenomena, uncertainty and sensitivity studies, probabilistic assessments, preliminary safety analyses of Gorleben.

STUDY ON BIODEGRADABILITY OF POLY (3-HYDROXYBUTYRATE-co-3-HYDROXYVALERATE)/ORGANOPHILIC MONTMORILLONITE NANOCOMPOSITES

Institute of Scientific and Technical Information of China (English)

WANG Shufang; SONG Cunjiang; CHEN Guangxin; LIU Jing; YANG Chao; ZHANG Xihui; GUO Tianying; ZHANG Banghua

2004-01-01

Poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/Organophilic montmorillonite (PHBV/OMMT) nanocomposites were prepared and the biodegradability of the PHBV/OMMT nanocomposites was studied by a cultivation degrading method in soil suspension. The relationship between structure and biodegradability of PHBV/OMMT nanocomposites was investigated. The results showed that the biodegradability of PHBV/OMMT nanocomposites decreased with increasing amount of OMMT and it was related to the number of PHBV degrading microorganisms in degradation environment, the anti-microbial property of OMMT and the degree of crystallinity of the nanocomposites.

Investigations of thermal barrier coatings of turbine parts using gas flame heating

Science.gov (United States)

Lepeshkin, A. R.; Bichkov, N. G.; Ilinskaja, O. I.; Nazarov, V. V.

2017-09-01

The development of methods for the calculated and experimental investigations thermal barrier coatings and thermal state of gas-turbine engine parts with a thermal barrier coatings is actual work. The gas flame heating was demonstrated to be effectively used during investigations of a thermal ceramic barrier coatings and thermal state of such gas-turbine engine parts with a TBC as the cooled turbine blades and vanes and combustion liner components. The gas-flame heating is considered to be preferable when investigating the gas-turbine engine parts with a TBC in the special cases when both the convective and radiant components of thermal flow are of great importance. The small-size rig with gas-flame flow made it possible to conduct the comparison investigations with the purpose of evaluating the efficiency of thermal protection of the ceramic deposited thermal barrier coatings on APS and EB techniques. The developed design-experiment method was introduced in bench tests of turbine blades and combustion liner components of gas turbine engines.