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Sample records for sorption cryocooler system

  1. Dynamic Simulation of a Periodic 10 K Sorption Cryocooler

    Science.gov (United States)

    Bhandari, P.; Rodriguez, J.; Bard, S.; Wade, L.

    1994-01-01

    A transient thermal simulation model has been developed to simulate the dynamic performance of a multiple-stage 10 K sorption cryocooler for spacecraft sensor cooling applications that require periodic quick-cooldown (under 2 minutes) , negligible vibration, low power consumption, and long life (5 to 10 years). The model was specifically designed to represent the Brilliant Eyes Ten-Kelvin Sorption Cryocooler Experiment (BETSCE), but it can be adapted to represent other sorption cryocooler systems as well. The model simulates the heat transfer, mass transfer, and thermodynamic processes in the cryostat and the sorbent beds for the entire refrigeration cycle, and includes the transient effects of variable hydrogen supply pressures due to expansion and overflow of hydrogen during the cooldown operation. The paper describes model limitations and simplifying assumptions, with estimates of errors induced by them, and presents comparisons of performance predictions with ground experiments. An important benefit of the model is its ability to predict performance sensitivities to variations of key design and operational parameters. The insights thus obtained are expected to lead to higher efficiencies and lower weights for future designs.

  2. 8th International Cryocooler Conference

    CERN Document Server

    1995-01-01

    The last few years have witnessed a substantial maturing of long life Stirling-cycle cryocoolers built upon the heritage of the flexure-bearing cryocoolers from Oxford University, and have seen the emergence of mature pulse tube cryocoolers competing head-to-head with the Stirling cryocoolers. Hydrogen sorption cryocoolers, Gifford-McMahon cryocoolers with rare earth regenerators, and helium Joule-Thomson cryocoolers have also made tremendous progress in opening up applications in the 4 K to 10 K temperature range. Tactical Stirling cryocoolers, now commonplace in the defense industry, are finding application in a number of cost­ constrained commercial applications and space missions, and are achieving ever longer lives as they move to linear-drive, clearance-seal compressors. Building on this expanding availability of commercially viable cryocoolers, numerous new applications are being enabled; many of these involve infrared imaging systems, and high­ temperature superconductors in the medical and ...

  3. Automated Cryocooler Monitor and Control System Software

    Science.gov (United States)

    Britchcliffe, Michael J.; Conroy, Bruce L.; Anderson, Paul E.; Wilson, Ahmad

    2011-01-01

    This software is used in an automated cryogenic control system developed to monitor and control the operation of small-scale cryocoolers. The system was designed to automate the cryogenically cooled low-noise amplifier system described in "Automated Cryocooler Monitor and Control System" (NPO-47246), NASA Tech Briefs, Vol. 35, No. 5 (May 2011), page 7a. The software contains algorithms necessary to convert non-linear output voltages from the cryogenic diode-type thermometers and vacuum pressure and helium pressure sensors, to temperature and pressure units. The control function algorithms use the monitor data to control the cooler power, vacuum solenoid, vacuum pump, and electrical warm-up heaters. The control algorithms are based on a rule-based system that activates the required device based on the operating mode. The external interface is Web-based. It acts as a Web server, providing pages for monitor, control, and configuration. No client software from the external user is required.

  4. Optimized autonomous operations of a 20 K space hydrogen sorption cryocooler

    Science.gov (United States)

    Borders, J.; Morgante, G.; Prina, M.; Pearson, D.; Bhandari, P.

    2004-06-01

    A fully redundant hydrogen sorption cryocooler is being developed for the European Space Agency Planck mission, dedicated to the measurement of the temperature anisotropies of the cosmic microwave background radiation with unprecedented sensitivity and resolution [Advances in Cryogenic Engineering 45A (2000) 499]. In order to achieve this ambitious scientific task, this cooler is required to provide a stable temperature reference (˜20 K) and appropriate cooling (˜1 W) to the two instruments on-board, with a flight operational lifetime of 18 months. During mission operations, communication with the spacecraft will be possible in a restricted time-window, not longer than 2 h/day. This implies the need for an operations control structure with the required robustness to safely perform autonomous procedures. The cooler performance depends on many operating parameters (such as the temperatures of the pre-cooling stages and the warm radiator), therefore the operation control system needs the capability to adapt to variations of these boundary conditions, while maintaining safe operating procedures. An engineering bread board (EBB) cooler was assembled and tested to evaluate the behavior of the system under conditions simulating flight operations and the test data were used to refine and improve the operation control software. In order to minimize scientific data loss, the cooler is required to detect all possible failure modes and to autonomously react to them by taking the appropriate action in a rapid fashion. Various procedures and schemes both general and specific in nature were developed, tested and implemented to achieve these goals. In general, the robustness to malfunctions was increased by implementing an automatic classification of anomalies in different levels relative to the seriousness of the error. The response is therefore proportional to the failure level. Specifically, the start-up sequence duration was significantly reduced, allowing a much faster

  5. Applications concepts of small regenerative cryocoolers in superconducitng magnet systems

    NARCIS (Netherlands)

    van der Laan, M.T.G.; van der Laan, M.T.G.; Tax, R.B.; ten Kate, Herman H.J.

    1992-01-01

    Superconducting magnets are in growing use outside laboratories for example MRI scanners in hospitals. Other applications under development are magnet systems for separation, levitated trains and ship propulsion. The application of cryocoolers can make these systems more practical. Interfacing these

  6. Automated Cryocooler Monitor and Control System

    Science.gov (United States)

    Britcliffe, Michael J.; Hanscon, Theodore R.; Fowler, Larry E.

    2011-01-01

    A system was designed to automate cryogenically cooled low-noise amplifier systems used in the NASA Deep Space Network. It automates the entire operation of the system including cool-down, warm-up, and performance monitoring. The system is based on a single-board computer with custom software and hardware to monitor and control the cryogenic operation of the system. The system provides local display and control, and can be operated remotely via a Web interface. The system controller is based on a commercial single-board computer with onboard data acquisition capability. The commercial hardware includes a microprocessor, an LCD (liquid crystal display), seven LED (light emitting diode) displays, a seven-key keypad, an Ethernet interface, 40 digital I/O (input/output) ports, 11 A/D (analog to digital) inputs, four D/A (digital to analog) outputs, and an external relay board to control the high-current devices. The temperature sensors used are commercial silicon diode devices that provide a non-linear voltage output proportional to temperature. The devices are excited with a 10-microamp bias current. The system is capable of monitoring and displaying three temperatures. The vacuum sensors are commercial thermistor devices. The output of the sensors is a non-linear voltage proportional to vacuum pressure in the 1-Torr to 1-millitorr range. Two sensors are used. One measures the vacuum pressure in the cryocooler and the other the pressure at the input to the vacuum pump. The helium pressure sensor is a commercial device that provides a linear voltage output from 1 to 5 volts, corresponding to a gas pressure from 0 to 3.5 MPa (approx. = 500 psig). Control of the vacuum process is accomplished with a commercial electrically operated solenoid valve. A commercial motor starter is used to control the input power of the compressor. The warm-up heaters are commercial power resistors sized to provide the appropriate power for the thermal mass of the particular system, and

  7. Preliminary test Results for a 25K Sorption Cryocooler Designed for the UCSB Long Duration Balloon Cosmic Microwave Background Radiation Experiment

    Science.gov (United States)

    Wade, L. A.; Levy, A. R.

    1996-01-01

    A continuous operation, vibration-free, long-life 25K sorption cryocooler has been built and is now in final integration and performance testing. This cooler wil be flown on the University of California at Santa Barbara (UCSB) Long Duration Balloon (LDB) Cosmic Microwave Background Radiation Experiment.

  8. Ultra-low-vibration pulse-tube cryocooler system - cooling capacity and vibration

    Science.gov (United States)

    Ikushima, Yuki; Li, Rui; Tomaru, Takayuki; Sato, Nobuaki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira

    2008-09-01

    This report describes the development of low-vibration cooling systems with pulse-tube (PT) cryocoolers. Generally, PT cryocoolers have the advantage of lower vibrations in comparison to those of GM cryocoolers. However, cooling systems for the cryogenic laser interferometer observatory (CLIO), which is a gravitational wave detector, require an operational vibration that is sufficiently lower than that of a commercial PT cryocooler. The required specification for the vibration amplitude in cold stages is less than ±1 μm. Therefore, during the development of low-vibration cooling systems for the CLIO, we introduced advanced countermeasures for commercial PT cryocoolers. The cooling performance and the vibration amplitude were evaluated. The results revealed that 4 K and 80 K PT cooling systems with a vibration amplitude of less than ±1 μm and cooling performance of 4.5 K and 70 K at heat loads of 0.5 W and 50 W, respectively, were developed successfully.

  9. Deep Space Cryocooler System (DSCS), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — As NASA missions continue to extend the horizon beyond near-Earth missions, higher performance systems must evolve to address the challenges of reduced power...

  10. Air liquide's space pulse tube cryocooler systems

    Science.gov (United States)

    Trollier, T.; Tanchon, J.; Buquet, J.; Ravex, A.

    2017-11-01

    Thanks to important development efforts completed with ESA funding, Air Liquide Advanced Technology Division (AL/DTA), is now in position to propose two Pulse Tube cooler systems in the 40-80K temperature range for coming Earth Observation missions such as Meteosat Third Generation (MTG), SIFTI, etc… The Miniature Pulse Tube Cooler (MPTC) is lifting up to 2.47W@80K with 50W compressor input power and 10°C rejection temperature. The weight is 2.8 kg. The Large Pulse Tube Cooler (LPTC) is providing 2.3W@50K for 160W input power and 10°C rejection temperature. This product is weighing 5.1 kg. The two pulse tube coolers thermo-mechanical units are qualified against environmental constraints as per ECSS-E-30. They are both using dual opposed pistons flexure bearing compressor with moving magnet linear motors in order to ensure very high lifetime. The associated Cooler Drive Electronics is also an important aspect specifically regarding the active control of the cooler thermo-mechanical unit during the launch phase and the active reduction of the vibrations induced by the compressor (partly supported by the French Agency CNES). This paper details the presentation of the two Pulse Tube Coolers together with the Cooler Drive Electronics aspects.

  11. Magnet/cryocooler integration for thermal stability in conduction-cooled systems

    Science.gov (United States)

    Chang, H.-M.; Kwon, K. B.

    2002-05-01

    The stability conditions that take into accounts the size of superconducting magnets and the refrigeration capacity of cryocoolers are investigated for the conduction-cooled systems without liquid cryogens. The worst scenario in the superconducting systems is that the heat generation in the resistive state exceeds the refrigeration, causing a rise in the temperature of the magnet winding and leading to burnout. It is shown by an analytical solution that in the continuously resistive state, the temperature may increase indefinitely or a stable steady state may be reached, depending upon the relative size of the magnet with respect to the refrigeration capacity of the cryocooler. The stability criteria include the temperature-dependent properties of the magnet materials and the refrigeration characteristics of the cryocooler. A useful graphical scheme is presented and the design of the stable magnet/cryocooler interface is demonstrated.

  12. Application of a Cryocooler in the Superconducting Magnet Cooling System

    International Nuclear Information System (INIS)

    Kowalczyk, W.; Malinowski, H.

    1998-01-01

    The application of the cryocooler working with a OGMS separator was suggested. It is very important to decrease the heat leak into the electromagnet. It was discussed how to reduce the heat leak into the separator's coils. The use of a high temperature superconducting current leads is proposed and calculated. (author)

  13. Development of a fluorescent cryocooler

    International Nuclear Information System (INIS)

    Edwards, B.C.; Buchwald, M.I.; Epstein, R.I.; Gosnell, T.R.; Mungan, C.E.

    1995-01-01

    Recent work at Los Alamos National Laboratory has demonstrated the physical principles for a new type of solid-state cryocooler based on anti-Stokes fluorescence. Design studies indicate that a vibration-free, low-mass ''fluorescent cryocooler'' could operate for years with efficiencies and cooling powers comparable to current commercial systems. This paper presents concepts for a fluorescent cryocooler, design considerations and expected performance

  14. Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas

    Energy Technology Data Exchange (ETDEWEB)

    Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

    2014-01-29

    In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

  15. Status of sorption information retrieval system

    International Nuclear Information System (INIS)

    Hostetler, D.D.; Serne, R.J.; Brandstetter, A.

    1979-09-01

    A Sorption Information Retrieval System (SIRS) is being designed to provide an efficient, computerized, data base for information on radionuclide sorption in geologic media. The data bank will include Kd values for a large number of radionuclides occurring in radioactive wastes originating from the commercial nuclear power industry. Kd values determined to date span several groundwater compositions and a wide variety of rock types and minerals. The data system will not only include Kd values, but also background information on the experiments themselves. This will allow the potential user to retrieve not only the Kd values of interest but also sufficient information to evaluate the accuracy and usefulness of the data. During FY-1979, the logic structure of the system was designed, the software programmed, the data categories selected, and the data format specified. About 40% of the approximately 5000 Kd experiments performed by the Waste Isolation Safety Assessment Program (WISAP) and its subcontractors during FY-1977 and FY-1978 have been evaluated, coded and keypunched. Additional software improvements and system testing are needed before the system will be fully operational. A workshop requested by the NEA was held to discuss potential internatioal participation in the data system

  16. Acoustic cryocooler

    International Nuclear Information System (INIS)

    Swift, G.W.; Martin, R.A.; Radebaugh, R.

    1990-01-01

    This patent describes an acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effect to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15--60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintain a cooling load of 5 W at 80 K

  17. Design of High Voltage Electrical Breakdown Strength measuring system at 1.8K with a G-M cryocooler

    Science.gov (United States)

    Li, Jian; Huang, Rongjin; Li, Xu; Xu, Dong; Liu, Huiming; Li, Laifeng

    2017-09-01

    Impregnating resins as electrical insulation materials for use in ITER magnets and feeder system are required to be radiation stable, good mechanical performance and high voltage electrical breakdown strength. In present ITER project, the breakdown strength need over 30 kV/mm, for future DEMO reactor, it will be greater than this value. In order to develop good property insulation materials to satisfy the requirements of future fusion reactor, high voltage breakdown strength measurement system at low temperature is necessary. In this paper, we will introduce our work on the design of this system. This measuring system has two parts: one is an electrical supply system which provides the high voltage from a high voltage power between two electrodes; the other is a cooling system which consists of a G-M cryocooler, a superfluid chamber and a heat switch. The two stage G-M cryocooler pre-cool down the system to 4K, the superfluid helium pot is used for a container to depress the helium to superfluid helium which cool down the sample to 1.8K and a mechanical heat switch connect or disconnect the cryocooler and the pot. In order to provide the sufficient time for the test, the cooling system is designed to keep the sample at 1.8K for 300 seconds.

  18. Status report on SIRS: sorption information retrieval system

    International Nuclear Information System (INIS)

    Hostetler, D.D.; Serne, R.J.; Baldwin, A.J.; Petrie, G.M.

    1980-11-01

    Two major uses were identified for the Sorption Information Retrieval System: (1) to aid geochemists in the elucidation of sorption mechanisms; and (2) to aid safety assessment modelers in selection of Kds for any given scenerio. Other benefits such as providing an auditable vehicle for the Kd selection were also discussed

  19. Pressure cryocooling protein crystals

    Science.gov (United States)

    Kim, Chae Un [Ithaca, NY; Gruner, Sol M [Ithaca, NY

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  20. Sorption data bases for generic Swiss argillaceous rock systems

    International Nuclear Information System (INIS)

    Bradbury, M. H.; Baeyens, B.; Thoenen, T.

    2010-09-01

    implies, these factors were used to convert the (predominantly) illite sorption values into sorption values valid for the defined generic conditions with regard to mineralogy and porewater composition. Conversion factors were used to adapt sorption values to mineralogy (CF min ), to pH value (CF pH ) and to radionuclide speciation (CF spec ). Finally, a Lab→Field conversion factor (CF Lab→Field ) was applied to adapt sorption data measured in dispersed systems (batch experiments) to intact rock under in-situ conditions. Calcareous rock is used in safety analyses as being representative of a clay rock which has lost most of its favorable sorption properties due to near-field effects such as alteration by an alkaline plume and subsequent processes. It is assumed that calcareous rocks do not contain any significant quantities of phyllosilicates and that only uptake data on calcite are relevant. Sorption data on calcite are extremely sparse and the uptake mechanisms are not fully understood. However, when the existing sorption data (log R d values) are plotted against the ionic radii of the respective metals, an acceptable linear correlation between these two quantities is found. This so-called linear free energy relationship is used to complement the sparse experimental data in the SDB for calcareous systems. (authors)

  1. Performance of chromatographic systems to model soil-water sorption.

    Science.gov (United States)

    Hidalgo-Rodríguez, Marta; Fuguet, Elisabet; Ràfols, Clara; Rosés, Martí

    2012-08-24

    A systematic approach for evaluating the goodness of chromatographic systems to model the sorption of neutral organic compounds by soil from water is presented in this work. It is based on the examination of the three sources of error that determine the overall variance obtained when soil-water partition coefficients are correlated against chromatographic retention factors: the variance of the soil-water sorption data, the variance of the chromatographic data, and the variance attributed to the dissimilarity between the two systems. These contributions of variance are easily predicted through the characterization of the systems by the solvation parameter model. According to this method, several chromatographic systems besides the reference octanol-water partition system have been selected to test their performance in the emulation of soil-water sorption. The results from the experimental correlations agree with the predicted variances. The high-performance liquid chromatography system based on an immobilized artificial membrane and the micellar electrokinetic chromatography systems of sodium dodecylsulfate and sodium taurocholate provide the most precise correlation models. They have shown to predict well soil-water sorption coefficients of several tested herbicides. Octanol-water partitions and high-performance liquid chromatography measurements using C18 columns are less suited for the estimation of soil-water partition coefficients. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. General review of solar-powered closed sorption refrigeration systems

    International Nuclear Information System (INIS)

    Sarbu, Ioan; Sebarchievici, Calin

    2015-01-01

    Highlights: • Provide review of development in solar sorption refrigeration technologies. • Theoretical basis and applications of absorption and adsorption cycles are discussed. • Thermodynamic properties of most common working pairs have been reviewed. • Development of hybrid or thermal energy storage adsorption systems was explored. • A comparison between solar-powered absorption and adsorption systems was performed. - Abstract: The negative environmental impacts of burning fossil fuels have forced the energy research community seriously to consider renewable sources, such as naturally available solar energy. Thermally powered refrigeration technologies are classified into two categories: thermo-mechanical technology and sorption technology (open systems or closed systems). This paper provides a detailed review of the solar closed sorption (absorption and adsorption) refrigeration systems, which utilise working pairs (fluids). After an introduction of the basic principles of these systems, the history of development and recent advances in solar sorption refrigeration technologies are reported. The adsorption cooling typically has a lower heat source temperature requirement than the absorption cooling. Based on the coefficient of performance (COP), the absorption systems are preferred over the adsorption systems, and the higher temperature issues can be easily handled with solar adsorption systems. The thermodynamic properties of most common working fluids, as well as the use of ternary mixtures in solar-powered absorption systems, have been reviewed in this study. The paper also refers to new approaches to increase the efficiency and sustainability of the basic adsorption cycles, such as the development of hybrid or thermal energy storage adsorption systems. This research shows that solar-powered closed sorption refrigeration technologies can be attractive alternatives not only to serve the needs for air-conditioning, refrigeration, ice making, thermal

  3. Integrated sorption and diffusion model for bentonite. Part 1. Clay-water interaction and sorption modeling in dispersed systems

    International Nuclear Information System (INIS)

    Tachi, Yukio; Suyama, Tadahiro; Ochs, Michael

    2014-01-01

    To predict the long-term migration of radionuclides (RNs) under variable conditions within the framework of safety analyses for geological disposal, thermodynamic sorption models are very powerful tools. The integrated sorption and diffusion (ISD) model for compacted bentonite was developed to achieve a consistent combination of clay–water interaction, sorption, and diffusion models. The basic premise considered in the ISD model was to consistently use the same simple surface model design and parameters for describing RNs sorption/diffusion as well as clay surface and porewater chemistry. A simple 1-site non-electrostatic surface complexation model in combination with a 1-site ion exchange model was selected to keep sorption model characteristics relatively robust for compacted systems. Fundamental parameters for the proposed model were evaluated from surface titration data for purified montmorillonite. The resulting basic model was then parameterized on the basis of selected published sorption data-sets for Np(V), Am(III), and U(VI) in dispersed systems, which cover a range of key geochemical conditions such as pH, ionic strength, and carbonate concentration. The sorption trends for these RNs can be quantitatively described by the model considering a full suite of surface species including hydrolytic and carbonate species. The application of these models to the description of diffusive-sorptive transport in compacted bentonites is presented in Part 2. (author)

  4. Nitrogen heat pipe for cryocooler thermal shunt

    International Nuclear Information System (INIS)

    Prenger F.C.; Hill, D.D.; Daney, D.E.

    1996-01-01

    A nitrogen heat pipe was designed, built and tested for the purpose of providing a thermal shunt between the two stages of a Gifford-McMahan (GM) cryocooler during cooldown. The nitrogen heat pipe has an operating temperature range between 63 and 123 K. While the heat pipe is in this temperature range during the system cooldown, it acts as a thermal shunt between the first and second stage of the cryocooler. The heat pipe increases the heat transfer to the first stage of the cryocooler, thereby reducing the cooldown time of the system. When the heat pipe temperature drops below the triple point, the nitrogen working fluid freezes, effectively stopping the heat pipe operation. A small heat leak between cryocooler stages remains because of axial conduction along the heat pipe wall. As long as the heat pipe remains below 63 K, the heat pipe remains inactive. Heat pipe performance limits were measured and the optimum fluid charge was determined

  5. Building the better cryocooler

    International Nuclear Information System (INIS)

    Radebaugh, R.

    1992-01-01

    This article focuses on the present and future status of small cryocoolers that may be useful for cooling superconducting electronics or magnets no larger than those of Magnetic Resonance Imaging (MRI) systems. In a few cases superconductors have found their way into a large market. The best example is superconducting Super Collider (SSC) and other accelerators use an enormous amount of superconducting wire and require large liquid helium plants for cooling. The costs of these large accelerator systems greatly restricts the number of such installations. Thin film superconducting electronic devices have the potential of being made relatively inexpensively and have a performance advantage over conventional electronic systems. The possible market size for superconducting electronics could be extremely large is one serious problem would simply disappear

  6. International Cryocooler Conference

    CERN Document Server

    Cryocoolers 13

    2005-01-01

    This is the 13th volume in the conference series. Over the years the International Cryocoolers Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature super-capacitor applications.

  7. A 4 K tactical cryocooler using reverse-Brayton machines

    Science.gov (United States)

    Zagarola, M.; Cragin, K.; McCormick, J.; Hill, R.

    2017-12-01

    Superconducting electronics and spectral-spatial holography have the potential to revolutionize digital communications, but must operate at cryogenic temperatures, near 4 K. Liquid helium is undesirable for military missions due to logistics and scarcity, and commercial low temperature cryocoolers are unable to meet size, weight, power, and environmental requirements for many missions. To address this need, Creare is developing a reverse turbo-Brayton cryocooler that provides refrigeration at 4.2 K and rejects heat at 77 K to an upper-stage cryocooler or through boil-off of liquid nitrogen. The cooling system is predicted to reduce size, weight, and input power by at least an order of magnitude as compared to the current state-of-the-art 4.2 K cryocooler. For systems utilizing nitrogen boil-off, the boil-off rate is reasonable. This paper reviews the design of the cryocooler, the key components, and component test results.

  8. 17th International Cryocooler Conference

    CERN Document Server

    Ross, Ronald G

    2012-01-01

    Cryocoolers 17 archives developments and performance measurements in the field of cryocoolers based on the contributions of leading international experts at the 17th International Cryocooler Conference that was held in Los Angeles, California, on July 9-12, 2012. The program of this conference consisted of 94 papers; of these, 71 are published here. Over the years the International Cryocoolers Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature superconductor applications.

  9. 16th International Cryocooler Conference

    CERN Document Server

    Ross, Ronald G

    2011-01-01

    Cryocoolers 16 archives developments and performance measurements in the field of cryocoolers based on the contributions of leading international experts at the 16th International Cryocooler Conference that was held in Atlanta, Georgia, on May 17-20, 2010. The program of this conference consisted of 116 papers; of these, 89 are published here. Over the years the International Cryocoolers Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature superconductor applications.

  10. Reversible Ammonia Sorption for the Primary Life Support System (PLSS)

    Science.gov (United States)

    Wojtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Jennings, Mallory A.

    2012-01-01

    Results are presented on the development of regenerable trace-contaminant (TC) sorbent for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). Since ammonia is the most important TC to be captured, data presented in this paper are limited to ammonia sorption, with results relevant to other TCs to be reported at a later time. The currently available TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal. The sorbent is non-regenerable, and its use is associated with appreciable pressure drop, i.e. power consumption. The objective of this work is to demonstrate the feasibility of using vacuum-regenerable sorbents for PLSS application. In this study, several carbon sorbent monoliths were fabricated and tested. Multiple adsorption/vacuum-regeneration cycles were demonstrated at room temperature, as well as carbon surface conditioning that enhances ammonia sorption without impairing sorbent regeneration. Depending on sorbent monolith geometry, the reduction in pressure drop with respect to granular sorbent was found to be between 50% and two orders of magnitude. Resistive heating of the carbon sorbent monolith was demonstrated by applying voltage to the opposite ends of the monolith.

  11. Sorption of Cs, I, and actinides in concrete systems

    International Nuclear Information System (INIS)

    Allard, B.; Eliasson, L.; Andersson, K.

    1984-09-01

    Samples of seven different concretes were prepared (Standard Portland cement of two kinds; sulphate resistant, blast furnace slag, high alumina, fly ash, and silica cements) and the corresponding pore waters were analyzed. Batch-wise distribution studies were performed in the various concrete/pore water systems, as well as for three old concrete samples from a hydro power station dam (more than 60 years old), for the elements Cs, I, Th, U, Np, Pu, and Am at trace concentration levels. Generally the sorption of Cs was low, and somewhat higher for I. All the actinides, including U and Np in their hexa- and pentavalent states, respectively, were strongly sorbed on the cement phase. (Author)

  12. The ternary sorption system U(VI)-phosphate-silica explained by spectroscopy and thermodynamic modelling

    Energy Technology Data Exchange (ETDEWEB)

    Foerstendorf, Harald; Stockmann, Madlen; Heim, Karsten; Mueller, Katharina; Brendler, Vinzenz [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Comarmond, M.J.; Payne, T.E. [Australian Nuclear Science and Technology Organisation, Lucas Heights (Australia); Steudtner, Robin [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Resource Ecology

    2017-06-01

    Spectroscopic data of sorption processes potentially provide direct impact on Surface Complexation Modelling (SCM) approaches. Based on spectroscopic data of the ternary sorption system U(VI)/phosphate/silica strongly suggesting the formation of a precipitate as the predominant surface process, SCM calculations accurately reproduced results from classical batch experiments.

  13. The ternary sorption system U(VI)-phosphate-silica explained by spectroscopy and thermodynamic modelling

    International Nuclear Information System (INIS)

    Foerstendorf, Harald; Stockmann, Madlen; Heim, Karsten; Mueller, Katharina; Brendler, Vinzenz; Steudtner, Robin

    2017-01-01

    Spectroscopic data of sorption processes potentially provide direct impact on Surface Complexation Modelling (SCM) approaches. Based on spectroscopic data of the ternary sorption system U(VI)/phosphate/silica strongly suggesting the formation of a precipitate as the predominant surface process, SCM calculations accurately reproduced results from classical batch experiments.

  14. 18th International Cryocooler Conference

    CERN Document Server

    Ross, Ronald G

    2014-01-01

    Cryocoolers 18 Cryocoolers 18 archives developments and performance measurements in the field of cryocoolers based on the contributions of leading international experts at the 18th International Cryocooler Conference that was held in Syracuse, New York, on June 9-12, 2014. The program of this conference lead to the 76 peer-reviewed papers that are published here. Over the years the International Cryocoolers Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature superconductor applications.

  15. 10th International Cryocooler Conference

    CERN Document Server

    2002-01-01

    Cryocoolers 10 is the premier archival publication of the latest advances and performance of small cryogenic refrigerators designed to provide localized cooling for military, space, semi-conductor, medical, computing, and high-temperature superconductor cryogenic applications in the 2-200 K temperature range. Composed of papers written by leading engineers and scientists in the field, Cryocoolers 10 reports the most recent advances in cryocooler development, contains extensive performance test results and comparisons, and relates the latest experience in integrating cryocoolers into advanced applications.

  16. Highly Effective Thermal Regenerator for Low Temperature Cryocoolers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Future missions to investigate the structure and evolution of the universe require highly efficient, low-temperature cryocoolers for low-noise detector systems. We...

  17. Experimental determination of sorption in fractured flow systems

    Science.gov (United States)

    Zimmerman, Mitchell D.; Bennett, Philip C.; Sharp, John M.; Choi, Wan-Joo

    2002-09-01

    Fracture "skins" are alteration zones on fracture surfaces created by a variety of biological, chemical, and physical processes. Skins increase surface area, where sorption occurs, compared to the unaltered rock matrix. This study examines the sorption of organic solutes on altered fracture surfaces in an experimental fracture-flow apparatus. Fracture skins containing abundant metal oxides, clays, and organic material from the Breathitt Formation (Kentucky, USA) were collected in a manner such that skin surface integrity was maintained. The samples were reassembled in the lab in a flow-through apparatus that simulated ˜2.7 m of a linear fracture "conduit." A dual-tracer injection scheme was utilized with the sorbing or reactive tracer compared to a non-reactive tracer (chloride) injected simultaneously. Sorption was assessed from the ratio of the first temporal moments of the breakthrough curves and from the loss of reactive tracer mass and evaluated as a function of flow velocity and solute type. The breakthrough curves suggest dual-flow regimes in the fracture with both sorbing and non-sorbing flow fields. Significant sorption occurs for the reactive components, and sorption increased with decreasing flow rate and decreasing compound solubility. Based on moment analysis, however, there was little retardation of the center of solute mass. These data suggest that non-equilibrium sorption processes dominate and that slow desorption and boundary layer diffusion cause extensive tailing in the breakthrough curves.

  18. Sorption of norfloxacin, sulfamerazine and oxytetracycline by KOH-modified biochar under single and ternary systems.

    Science.gov (United States)

    Luo, Jiwei; Li, Xue; Ge, Chengjun; Müller, Karin; Yu, Huamei; Huang, Peng; Li, Jiatong; Tsang, Daniel C W; Bolan, Nanthi S; Rinklebe, Jörg; Wang, Hailong

    2018-05-08

    Pollution of water by single antibiotics has been investigated in depth. However, in reality, a wide range of different contaminants is often mixed in the aquatic environment (contaminant cocktail). Here, single and competitive sorption dynamics of ionizable norfloxacin (NOR), sulfamerazine (SMR) and oxytetracycline (OTC) by both pristine and modified biochars were investigated. Sorption kinetics of the three antibiotics was faster in ternary-solute than single-solute system. Sorption efficiency was enhanced in the competitive system for NOR by the pristine biochar, and for OTC by both the pristine biochar and the modified biochar, while SMR sorption by the pristine biochar and the KOH-modified biochar was inhibited. Sorption was governed by electrostatic interactions, π-π EDA and H-bonds for antibiotics sorption by biochar. SMR and OTC sorption by biochar was influenced by cation bridging and surface complexation, respectively. This research finding will guide the development of treatment procedures for water polluted by multiple antibiotics. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Cryocooler applications for high-temperature superconductor magnetic bearings

    International Nuclear Information System (INIS)

    Niemann, R. C.

    1998-01-01

    The efficiency and stability of rotational magnetic suspension systems are enhanced by the use of high-temperature superconductor (HTS) magnetic bearings. Fundamental aspects of the HTS magnetic bearings and rotational magnetic suspension are presented. HTS cooling can be by liquid cryogen bath immersion or by direct conduction, and thus there are various applications and integration issues for cryocoolers. Among the numerous cryocooler aspects to be considered are installation; operating temperature; losses; and vacuum pumping

  20. Autoradiographic studies of actinide sorption in groundwater systems

    International Nuclear Information System (INIS)

    O'Kelley, G.D.; Beall, G.W.; Allard, B.

    1980-01-01

    Autoradiography is a convenient and sensitive technique for the study of spacial distributions of alpha radioactive nuclides on slabs of rock or on other planar surfaces. The autoradiographic camera contains an arrangement for placing in firm contact Polaroid sheet film, a plastic scintillator screen, and the radioactive face of the specimen. As an example of the use of the autoradiographic method, a series of sorption experiments were carried out in which synthetic groundwater solutions of americium, neptunium, uranium, and plutonium were contacted with Climax Stock granite under aerated and anoxic conditions at pH 8 to 9. The sorption observed at specific mineral sites was correlated with data on sorption of these actinides on pure minerals

  1. Review of the Oxford Cryocooler

    International Nuclear Information System (INIS)

    Davey, G.

    1990-01-01

    The Oxford Cryocooler incorporates a linear drive compressor operating close to resonance. All dynamic seals are noncontacting clearance seals maintained by mounting the piston and displacer on mechanical suspension systems with infinite fatigue life. The displacer is pneumatically driven but controlled by a miniature linear motor. The cooler is therefore nonwearing and performance can be maintained even in adverse environments by servo control of piston and displacer strokes and relative phase. Split and integral, single- and two-stage coolers have been produced with operating temperatures between 30 K and 200 K, refrigeration powers between 50 mW and several watts and capable of operating in ambient temperatures from -40 C to 70 C. A current project aims to extend the refrigeration power to 500 watts at 80 K. Experimental optimisation techniques have been devised for rapid development of high efficiency coolers

  2. An efficient cooling loop for connecting cryocooler to a helium reservoir

    International Nuclear Information System (INIS)

    Taylor, C.E.; Abbott, C.S.R.; Leitner, D.; Leitner, M.; Lyneis, C.M.

    2003-01-01

    The magnet system of the VENUS ECR Ion Source at LBNL has two 1.5-watt cryocoolers suspended in the cryostat vacuum. Helium vapor from the liquid reservoir is admitted to a finned condenser bolted to the cryocooler 2nd stage and returns as liquid via gravity. Small-diameter flexible tubes allow the cryocoolers to be located remotely from the reservoir. With 3.1 watts load, the helium reservoir is maintained at 4.35 K, 0.05K above the cryocooler temperature. Design, analysis, and performance are presented

  3. 4th International Cryocoolers Conference

    CERN Document Server

    Patton, George; Knox, Margaret

    1987-01-01

    The Cryocoolers 4 proceedings archives the contributions of leading international experts at the 4th International Cryocooler Conference that was held in Easton, Maryland on September 25-26, 1986. About 170 people attended the conference representing 11 countries, 14 universities, 21 government laboratories and 60 industrial companies. Thirty-one papers were presented describing advancements and applications of cryocoolers in the temperature range below 80K. This year's conference was sponsored by the David Taylor Naval Ship Research and Development Center of Annapolis, Maryland, and the conference proceedings reproduced here was published by them.

  4. A FIXED BED SORPTION SYSTEM FOR DEFLUORIDATION OF GROUND WATER

    Directory of Open Access Journals (Sweden)

    Ayoob Sulaiman

    2009-06-01

    Full Text Available The presence of excess fluoride in ground water has become a global threat with as many as 200 million people affected in more than 35 countries in all the continents. Of late, there have been significant advances in the knowledge base regarding the effects of excess fluoride on human health. As a result, defluoridation of ground water is regarded as one of the key areas of attention among the universal water community triggering global research. This study describes the sorptive responses of a newly developed adsorbent, alumina cement granules (ALC, in its real-life application in fixed beds, for removing fluoride from the ground waters of a rural Indian village. ALC exhibited almost consistent scavenging capacity at various bed depths in column studies with an enhanced adsorption potential of 0.818 mg/g at a flow rate of 4 ml/min. The Thomas model was examined to describe the sorption process. The process design parameters of the column were obtained by linear regression of the model. In all the conditions examined, the Thomas model could consistently predict its characteristic parameters and describe the breakthrough sorption profiles in the whole range of sorption process.

  5. MODIL cryocooler producibility demonstration project results

    International Nuclear Information System (INIS)

    Cruz, G.E.; Franks, R.M.

    1993-01-01

    The production of large quantities of spacecraft needed by SDIO will require a cultural change in design and production practices. Low rates production and the need for exceedingly high reliability has driven the industry to custom designed, hand crafted, and exhaustively tested satellites. These factors have mitigated against employing design and manufacturing cost reduction methods commonly used in tactical missile production. Additional challenges to achieving production efficiencies are presented by the SDI spacecraft mission requirement. IR sensor systems, for example, are comprised of subassemblies and components that require the design, manufacture, and maintenance of ultra precision tolerances over challenging operational lifetimes. These IR sensors demand the use of reliable, closed loop, cryogenic refrigerators or active cryocoolers to meet stringent system acquisition and pointing requirements. The authors summarize some spacecraft cryocooler requirements and discuss observations regarding Industry's current production capabilities of cryocoolers. The results of the Lawrence Livermore National Laboratory (LLNL) Spacecraft Fabrication and Test (SF and T) MODIL's Phase I producibility demonstration project is presented

  6. 15th International Cryocooler Conference

    CERN Document Server

    Ross, Ronald G

    2009-01-01

    This is the 15th volume in the conference series. Over the years the International Cryocooler Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature superconductor applications.

  7. 14th International Cryocooler Conference

    CERN Document Server

    Ross, Ronald G

    2007-01-01

    This is the 14th volume in the conference series. Over the years the International Cryocoolers Conference has become the preeminent worldwide conference for the presentation of the latest developments and test experiences with cryocoolers. The typical applications of this technology include cooling space and terrestrial infrared focal plane arrays, space x-ray detectors, medical applications, and a growing number of high-temperature superconductor applications.

  8. Design of a Two-stage High-capacity Stirling Cryocooler Operating below 30K

    Science.gov (United States)

    Wang, Xiaotao; Dai, Wei; Zhu, Jian; Chen, Shuai; Li, Haibing; Luo, Ercang

    The high capacity cryocooler working below 30K can find many applications such as superconducting motors, superconducting cables and cryopump. Compared to the GM cryocooler, the Stirling cryocooler can achieve higher efficiency and more compact structure. Because of these obvious advantages, we have designed a two stage free piston Stirling cryocooler system, which is driven by a moving magnet linear compressor with an operating frequency of 40 Hz and a maximum 5 kW input electric power. The first stage of the cryocooler is designed to operate in the liquid nitrogen temperature and output a cooling power of 100 W. And the second stage is expected to simultaneously provide a cooling power of 50 W below the temperature of 30 K. In order to achieve the best system efficiency, a numerical model based on the thermoacoustic model was developed to optimize the system operating and structure parameters.

  9. A high efficiency hybrid stirling-pulse tube cryocooler

    Directory of Open Access Journals (Sweden)

    Xiaotao Wang

    2015-03-01

    Full Text Available This article presented a hybrid cryocooler which combines the room temperature displacers and the pulse tube in one system. Compared with a traditional pulse tube cryocooler, the system uses the rod-less ambient displacer to recover the expansion work from the pulse tube cold end to improve the efficiency while still keeps the advantage of the pulse tube cryocooler with no moving parts at the cold region. In the meantime, dual-opposed configurations for both the compression pistons and displacers reduce the cooler vibration to a very low level. In the experiments, a lowest no-load temperature of 38.5 K has been obtained and the cooling power at 80K was 26.4 W with an input electric power of 290 W. This leads to an efficiency of 24.2% of Carnot, marginally higher than that of an ordinary pulse tube cryocooler. The hybrid configuration herein provides a very competitive option when a high efficiency, high-reliability and robust cryocooler is desired.

  10. Cadmium removal by bioclastic granules (Lithothamnium calcareum): batch and fixed-bed column systems sorption studies.

    Science.gov (United States)

    Veneu, Diego Macedo; Schneider, Claudio Luiz; de Mello Monte, Marisa Bezerra; Cunha, Osvaldo Galvão Caldas; Yokoyama, Lídia

    2017-06-19

    The potential of Bioclastic Granules - BG (calcium-carbonate-based material) using the algae Lithothamnium calcareum as sorbent for the removal of Cd(II) from aqueous solutions by sorption was evaluated through batch and continuous systems tests using a fixed-bed column. Sorption process variables, in particular pH (2-7), particle size (<38-300 μm), initial BG concentration (0.1-1.0 g L -1 ), initial Cd(II) concentrations (5-400 mg L -1 ) and contact time (5-240 min), were evaluated. Adsorption isotherm profiles of Cd(II) per BG were similar to an L-type, or Langmuir type, with the adsorption forming a monolayer of approximately 0.61 μm, with a q max of 188.74 mg g -1 and k L of 0.710 L mg -1 . Thomas's model considers that sorption is not limited to a chemical reaction but is controlled by mass transfer at the interface. In the present study, the obtained value of k Th was 0.895 mL h -1  mg -1 , reaching a sorption capacity q o of 124.4 mg g -1 . For the Yoon-Nelson model, it was possible to obtain two important parameters to describe the behavior of the column, the rate constant (k YN ), obtaining a value of 0.09 h -1 and an τ of 82.12 h corresponding to the time required for sorption to occur of 50% of the solute in the rupture curve. X-ray diffraction and scanning electron microscopy analyses coupled to the X-ray dispersive energy system (SEM/EDS) of the BG after the Cd(II) ion sorption tests evidenced the formation of crystals with the prevalence of a new mineral phase (otavite).

  11. Outgas analysis of mechanical cryocoolers for long lifetime

    Science.gov (United States)

    Sato, Yoichi; Shinozaki, Keisuke; Sawada, Kenichiro; Sugita, Hiroyuki; Mitsuda, Kazuhisa; Yamasaki, Noriko Y.; Nakagawa, Takao; Tsunematsu, Shoji; Otsuka, Kiyomi; Kanao, Kenichi; Yoshida, Seiji; Narasaki, Katsuhiro

    2017-12-01

    Mechanical cryocoolers for space applications are required to have high reliability to achieve long-term operation in orbit. ASTRO-H (Hitomi), the 6th Japanese X-ray astronomy mission, has a major scientific instrument onboard-the Soft X-ray Spectrometer (SXS) with several 20K-class two-stage Stirling (2ST) coolers and a 4K-class Joule Thomson (JT) cooler, which must operate for 3 years to ensure the lifetime of liquid helium as a cryogen for cooling of its detectors [1,2]. Other astronomical missions such as SPICA [3,4], LiteBIRD [5], and Athena [6] also have top requirements for these mechanical cryocoolers, including a 1K-class JT cooler to be operated for more than 3-5 years with no cryogen system. The reliability and lifetime of mechanical cryocoolers are generally understood to depend on (1) mechanical wear of the piston seal and valve seal, and (2) He working gas contaminated by impurity outgases, mainly H2O and CO2 released from the materials in the components of the cryocoolers. The second factor could be critical relative to causing blockage in the JT heat exchanger plumbing and the JT orifice or resulting in blockage in the Stirling regenerator and thereby degrading its performance. Thus, reducing the potential for outgassing in the cryocooler design and fabrication process, and predicting the total amount of outgases in the cryocooler are very important to ensure cryocooler lifetime and cooling performance in orbit. This paper investigates the outgas analysis of the 2ST and the 1K/4K-JT coolers for achieving a long lifetime. First, gas analysis was conducted for the materials and components of the mechanical cryocoolers, focusing on non-metallic materials as impurity gas sources. Then gas analysis of the mechanical wear effect of the piston seal materials and linear ball bearings was investigated. Finally, outgassing from a fully assembled cryocooler was measured to evaluate whether the outgas reduction process works properly to meet the requirement

  12. New Approach for Description of Sorption and Swelling phenomena in Liquid + Polymer Membrane Systems.

    Czech Academy of Sciences Publication Activity Database

    Randová, A.; Bartovská, L.; Hovorka, Š.; Bartovský, T.; Izák, Pavel; Kárászová, Magda; Vopička, O.; Lindnerová, V.

    2017-01-01

    Roč. 179, MAY (2017), s. 475-485 ISSN 1383-5866 R&D Projects: GA MŠk(CZ) LD14094 Institutional support: RVO:67985858 Keywords : description of sorption * polymer membranes systems * new method Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 3.359, year: 2016

  13. Fatigue stress detection of VIRTIS cryocoolers on board Rosetta

    Science.gov (United States)

    Giuppi, Stefano; Politi, Romolo; Capria, Maria Teresa; Piccioni, Giuseppe; De Sanctis, Maria Cristina; Erard, Stéphane; Tosi, Federico; Capaccioni, Fabrizio; Filacchione, Gianrico

    Rosetta is a planetary cornerstone mission of the European Space Agency (ESA). It is devoted to the study of minor bodies of our solar system and it will be the first mission ever to land on a comet (the Jupiter-family comet 67P/Churyumov-Gerasimenko). VIRTIS-M is a sophisticated imaging spectrometer that combines two data channels in one compact instrument, respectively for the visible and the infrared range (0.25-5.0 μm). VIRTIS-H is devoted to infrared spectroscopy (2.5-5.0 μm) with high spectral resolution. Since the satellite will be inside the tail of the comet during one of the most important phases of the mission, it would not be appropriate to use a passive cooling system, due to the high flux of contaminants on the radiator. Therefore the IR sensors are cooled by two Stirling cycle cryocoolers produced by RICOR. Since RICOR operated life tests only on ground, it was decided to conduct an analysis on VIRTIS onboard Rosetta telemetries with the purpose of study possible differences in the cryocooler performancies. The analysis led to the conclusion that cryocoolers, when operating on board, are subject to a fatigue stress not present in the on ground life tests. The telemetries analysis shows a cyclic variation in cryocooler rotor angular velocity when -M or -H or both channel are operating (it has been also noted an influence of -M channel operations in -H cryocooler rotor angular velocity and vice versa) with frequencies mostly linked to operational parameters values. The frequencies have been calculated for each mission observation applying the Fast Fourier Transform (FFT). In order to evaluate possible hedge effects it has been also applied the Hanning window to compare the results. For a more complete evaluation of cryocoolers fatigue stress, for each mission observation the angular acceleration and the angular jerk have been calculated.

  14. Recent development status of compact 2 K GM cryocoolers

    Science.gov (United States)

    Bao, Q.; Xu, M. Y.; Tsuchiya, A.; Li, R.

    2015-12-01

    To meet the growing demand for a compact cooling solution for superconducting electronic devices, we developed a two-stage 2 K GM cryocooler and a cryostat system, which can reach 46.3 K / 2.2 K on the first and second stages under no-load conditions. Nevertheless, with several innovative technologies applied, the total length of the expander cylinder is reduced to under 70% of the smallest conventional 4 K GM cryocooler. In this paper we will present the design method, including material selection and structure design with detailed explanation, which has been confirmed by both simulation and experiment.

  15. CFD analysis of a diaphragm free-piston Stirling cryocooler

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-10-01

    This paper presents a Computational Fluid Dynamics (CFD) analysis of a novel free-piston Stirling cryocooler that uses a pair of metal diaphragms to seal and suspend the displacer. The diaphragms allow the displacer to move without rubbing or moving seals. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicated the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. The diaphragm's large diameter and short stroke produces a significant radial component to the oscillating flow fields inside the cryocooler which were not modelled in the one-dimensional analysis tool Sage that was used to design the prototypes. Compared with standard pistons, the diaphragm geometry increases the gas-to-wall heat transfer due to the higher velocities and smaller hydraulic diameters. A Computational Fluid Dynamics (CFD) model of the cryocooler was constructed to understand the underlying fluid-dynamics and heat transfer mechanisms with the aim of further improving performance. The CFD modelling of the heat transfer in the radial flow fields created by the diaphragms shows the possibility of utilizing the flat geometry for heat transfer, reducing the need for, and the size of, expensive heat exchangers. This paper presents details of a CFD analysis used to model the flow and gas-to-wall heat transfer inside the second prototype cryocooler, including experimental validation of the CFD to produce a robust analysis.

  16. Effects of oil dispersant on solubilization, sorption and desorption of polycyclic aromatic hydrocarbons in sediment–seawater systems

    International Nuclear Information System (INIS)

    Zhao, Xiao; Gong, Yanyan; O’Reilly, S.E.; Zhao, Dongye

    2015-01-01

    Highlights: • Oil dispersant enhances solubilization of PAHs more effectively than surfactants. • Dispersant and dispersed oil enhance sediment sorption of PAHs and induce hysteresis. • Partitioning to sediment-sorbed dispersant is the mechanism for enhanced PAH uptake. • Dual-mode models well simulate dispersant-facilitated sorption of PAHs on sediment. • Deepwater conditions reduce solubilization of PAHs and lessen dispersant effects. - Abstract: This work investigated effects of a prototype oil dispersant on solubilization, sorption and desorption of three model PAHs in sediment–seawater systems. Increasing dispersant dosage linearly enhanced solubility for all PAHs. Conversely, the dispersant enhanced the sediment uptake of the PAHs, and induced significant desorption hysteresis. Such contrasting effects (adsolubilization vs. solubilization) of dispersant were found dependent of the dispersant concentration and PAH hydrophobicity. The dual-mode models adequately simulated the sorption kinetics and isotherms, and quantified dispersant-enhanced PAH uptake. Sorption of naphthalene and 1-methylnaphthalene by sediment positively correlated with uptake of the dispersant, while sorption of pyrene dropped sharply when the dispersant exceeded its critical micelle concentration (CMC). The deepwater conditions diminished the dispersant effects on solubilization, but enhanced uptake of the PAHs, albeit sorption of the dispersant was lowered. The information may aid in understanding roles of dispersants on distribution, fate and transport of petroleum PAHs in marine systems

  17. 5th International Conference on Cryocoolers

    CERN Document Server

    1989-01-01

    The Cryocoolers 5 proceedings archives the contributions of leading international experts at the 5th International Cryocooler Conference that was held in Monterey, California on August 18-19, 1988. The authors submitted twenty six papers describing advancements and applications of cryocoolers in the temperature range below 80K. This year's conference was hosted by the U.S. Naval Postgraduate School in Monterey, California, and the conference proceedings reproduced here were published by the Wright-Patterson AFB in Ohio.

  18. Development of the sorption and diffusion database system for safety assessment of geological disposal

    International Nuclear Information System (INIS)

    Tachi, Yukio; Tochigi, Yoshikatsu; Suyama, Tadahiro; Saito, Yoshihiko; Yui, Mikazu; Ochs, Michael

    2009-02-01

    Japan Atomic Energy Agency (JAEA) has been developing databases of sorption and diffusion parameters in buffer material (bentonite) and rock, which are key parameters for safety assessment of the geological disposal. These sorption and diffusion databases (SDB/DDB) have been firstly developed as an important basis for the H12 performance assessment (PA) of high-level radioactive waste disposal in Japan, and have been provided through the Web. JAEA has been and is continuing to improve and update the SDB/DDB in view of potential future data needs, focusing on assuring the desired quality level and testing the usefulness of the existing databases for possible applications to parameter-setting for the deep geological environment. The new web-based sorption and diffusion database system (JAEA-SDB/DDB) has been developed to utilize quality assuring procedure and to allow effective application for parameter setting, by adding the following functions to the existing database; - consistency and linkage between sorption and diffusion database - effective utilization of quality assuring (QA) guideline and categolized QA data - additional function for estimating of parameters and graphing of relation between parameters - counting and summarizing function for effective access to respective data for parameter setting. In the present report, practical examples were illustrated regarding the applicability of the database system to the parameter setting by using additional functions such as QA information and data estimation. This database system is expected to make it possible to obtain quick overview of the available data from the database, and to have suitable access to the respective data for parameter-setting for performance assessment and parameter-deriving for mechanistic modeling in traceable and transparent manner. (author)

  19. Phosphorus Sorption Capacity of Gray Forest Soil as Dependent on Fertilization System

    Science.gov (United States)

    Rogova, O. B.; Kolobova, N. A.; Ivanov, A. L.

    2018-05-01

    In this paper, the results of the study of changes in the phosphorus sorption capacity of gray forest soils of Vladimir opolie under the impact of different fertilization systems are discussed. The quantitative parameters of the potential buffer capacity of soils for phosphorus (PBCP) and Langmuir sorption isotherms have been calculated. It is shown that the application of organic fertilizers results in a stronger decrease in PBCP than the application of mineral fertilizers. The portion of phosphorus of mineral compounds considerably increases, and the high content of available phosphates is maintained. In the variants with application of mineral phosphorus in combination with manure, the portions of organic and mineral phosphorus are at the level typical of unfertilized soils. The energy of phosphate bonds with the soil is minimal upon the application of a double rate of mineral phosphorus at the maximum capacity in relation to phosphate ions.

  20. Sorption and migration characteristics of 137Cs and 90Sr in natural dispersed systems

    International Nuclear Information System (INIS)

    Lishtvan, I.I.; Brovka, G.P.; Dedyulya, I.V.; Rovdan, E.N.

    1996-01-01

    Sorption and migration characteristics of 137 Cs and 90 Sr have been determined in fen peat, Quarts sand, kaolin and bentonite. An electrolyte effect on the radio nuclides sorption and diffusion in the given systems has been studied. Presence of stable isotopes of cesium and strontium in the porous solution has been revealed to affect 137 Cs and 90 Sr distribution and diffusion indices permitting for the effective diffusion index to increase by two orders of magnitude. 137 Cs in the peat technical contamination resulting from the Chernobyl NPP accident has been found to be mainly in an exchange form and under steady state conditions up to 75% of 137 Cs can be transformed into water-soluble state for 8-12 months under effect of stable cesium chloride (0.2 (g-eq)/l). (authors). 4 tabs., 4 refs

  1. Ab-sorption machines for heating and cooling in future energy systems - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Tozer, R.; Gustafsson, M.

    2000-12-15

    After the Executive Summary and a brief introductory chapter, Chapter 2, Sorption Technologies for Heating and Cooling in Future Energy Systems, reviews the main types of sorption systems. Chapter 3, Market Segmentation, then considers the major segments of the market including residential, commercial/institutional and industrial, and the types of sorption hardware most suitable to each. The highly important residential and commercial/institutional markets are mostly concerned with air-conditioning of buildings. More applications are identified and discussed for the industrial market, including refrigeration, food-storage cooling, process cooling, and process heating at various temperature ranges from hot water for hand-washing to high-temperature (greater than 130C). Other interesting industrial applications are absorption cooling or heating combined with co-generation, desiccant cooling, gas turbine inlet air cooling, combining absorption chillers with district heating systems, direct-fired absorption heat pumps (AHPs), and a closed greenhouse concept being developed for that economically important sector in the Netherlands. Most of the sorption market at this time comprises direct-fired absorption chillers, or hot water or steam absorption chillers indirectly driven by direct-fired boilers. Throughout the report, this category of absorption chillers is referred to generically as 'direct-fired'. In addition, this report covers absorption (reversible) heat pumps, absorption heat transformers, compression-absorption heat pumps, and adsorption chillers and heat pumps. Adsorption systems together with desiccant systems are also addressed. Chapter 4, Factors Affecting the Market, considers economic, environmental and policy issues. The geographical make-up of the world sorption market is then reviewed, followed by a number of practical operating and control considerations. These include vacuum requirements, crystallisation, corrosion, maintenance, health and

  2. Advanced, Long-Life Cryocooler Technology for Zero-Boil-Off Cryogen Storage, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Long-life, high-capacity cryocoolers are a critical need for future space systems utilizing stored cryogens. The cooling requirements for planetary and...

  3. Advanced, Long-Life Cryocooler Technology for Zero-Boil-Off Cryogen Storage, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Long-life, high-capacity cryocoolers are a critical need for future space systems utilizing stored cryogens. The cooling requirements for planetary and...

  4. Biotransformation and sorption of trace organic compounds in biological nutrient removal treatment systems.

    Science.gov (United States)

    Lakshminarasimman, Narasimman; Quiñones, Oscar; Vanderford, Brett J; Campo-Moreno, Pablo; Dickenson, Eric V; McAvoy, Drew C

    2018-05-28

    This study determined biotransformation rates (k bio ) and sorption-distribution coefficients (K d ) for a select group of trace organic compounds (TOrCs) in anaerobic, anoxic, and aerobic activated sludge collected from two different biological nutrient removal (BNR) treatment systems located in Nevada (NV) and Ohio (OH) in the United States (US). The NV and OH facilities operated at solids retention times (SRTs) of 8 and 23 days, respectively. Using microwave-assisted extraction, the biotransformation rates of the chosen TOrCs were measured in the total mixed liquor. Sulfamethoxazole, trimethoprim, and atenolol biotransformed in all three redox regimes irrespective of the activated sludge source. The biotransformation of N, N-diethyl-3-methylbenzamide (DEET), triclosan, and benzotriazole was observed in aerobic activated sludge from both treatment plants; however, anoxic biotransformation of these three compounds was seen only in anoxic activated sludge from NV. Carbamazepine was recalcitrant in all three redox regimes and both sources of activated sludge. Atenolol and DEET had greater biotransformation rates in activated sludge with a higher SRT (23 days), while trimethoprim had a higher biotransformation rate in activated sludge with a lower SRT (8 days). The remaining compounds did not show any dependence on SRT. Lyophilized, heat inactivated sludge solids were used to determine the sorption-distribution coefficients. Triclosan was the most sorptive compound followed by carbamazepine, sulfamethoxazole, DEET, and benzotriazole. The sorption-distribution coefficients were similar across redox conditions and sludge sources. The biotransformation rates and sorption-distribution coefficients determined in this study can be used to improve fate prediction of the target TOrCs in BNR treatment systems. Copyright © 2018. Published by Elsevier B.V.

  5. A free-piston Stirling cryocooler using metal diaphragms

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-12-01

    A novel concept for a free-piston Stirling cryocooler has been proposed. The concept uses a pair of metal diaphragms to seal and suspend the displacer of a free-piston Stirling cryocooler. The diaphragms allow the displacer to move without rubbing or moving seals, potentially resulting in a long-life mechanism. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicates the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. Sage predicted the macroscopic behaviour of the prototype well but did not provide sufficient insights to improve performance significantly. This paper presents details of the development, modelling and testing of the proof-of-concept prototype and a second, improved prototype.

  6. Soil microorganisms determine the sorption of radionuclides within organic soil systems

    International Nuclear Information System (INIS)

    Parekh, N.R.; Poskitt, J.M.; Dodd, B.A.; Potter, E.D.; Sanchez, A.

    2008-01-01

    The potential of soil microorganisms to enhance the retention of 137 Cs and 85 Sr in organic systems was assessed in a series of experiments. A biologically active, 'mineral-free', organic material, produced under laboratory conditions from leaves, was used as the uptake matrix in all experiments to minimise potential interference from competing clay minerals. Biological uptake and release were differentiated from abiotic processes by comparing the sorption of radionuclides in sterilised organic material with sterile material inoculated with soil extracts or single fungal strains. Our results show conclusively that living components of soil systems are of primary importance in the uptake of radionuclides in organic material. The presence of soil microorganisms significantly enhanced the retention of Cs in organic systems and ∼70% of the Cs spike was strongly (irreversibly) bound (remained non-extractable) in the presence of microorganisms compared to only ∼10% in abiotic systems. Sorption of 85 Sr was not significantly influenced by the presence of soil microorganisms. A non-linear temperature response was observed for the retention in biotic systems with increased uptake at between 10 and 30 deg. C and lower retention at temperatures above or below the optimum range. The optimum temperatures for biological uptake were between 15 and 20 deg. C for Cs, and 25 and 30 deg. C for Sr. Our results indicate that single strains of soil and saprotrophic fungi make an important contribution to the sorption of Cs and Sr in organic systems, but can only account for part of the strong, irreversible binding observed in biotic systems. Single strains of soil fungi increased the amount of non-extractable 137 Cs (by ∼30%) and 85 Sr (by ∼20%) in the organic systems as compared to abiotic systems, but the major fraction of 137 Cs and 85 Sr sorbed in systems inoculated with saprotrophic fungi remained extractable

  7. Technical aspects: development, manufacture and installation of a cryo-cooled HTS coil system for high-resolution in-vivo imaging of the mouse at 1.5 T.

    Science.gov (United States)

    Ginefri, Jean-Christophe; Poirier-Quinot, Marie; Girard, Olivier; Darrasse, Luc

    2007-09-01

    Signal-to-noise ratio improvement is of major importance to achieve microscopic spatial resolution in magnetic resonance experiments. Magnetic resonance imaging of small animals is particularly concerned since it typically requires voxels of less than (100 microm)(3) to observe the small anatomical structures having size reduction by a factor of more than 10 as compared to human being. The signal-to-noise ratio can be increased by working at high static magnetic field strengths, but the biomedical interest of such high-field systems may be limited due to field-dependent contrast mechanisms and severe technological difficulties. An alternative approach that allows working in clinical imaging system is to improve the sensitivity of the radio-frequency receiver coil. This can be done using small cryogenically operated coils made either of copper or high-temperature superconducting material. We report the technological development of cryo-cooled superconducting coils for high-resolution imaging in a whole-body magnetic resonance scanner operating at 1.5 T. The technological background supporting this development is first addressed, including HTS coil design, simulation tools, cryogenic mean description and electrical characterization procedure. To illustrate the performances of superconducting coils for magnetic resonance imaging at intermediate field strength, in-vivo mouse images of various anatomic sites acquired with a 12 mm diameter cryo-cooled superconducting coil are presented.

  8. Influence of minor geometric features on Stirling pulse tube cryocooler performance

    Science.gov (United States)

    Fang, T.; Spoor, P. S.; Ghiaasiaan, S. M.; Perrella, M.

    2017-12-01

    Minor geometric features and imperfections are commonly introduced into the basic design of multi-component systems to simplify or reduce the manufacturing expense. In this work, the cooling performance of a Stirling type cryocooler was tested in different driving powers, cold-end temperatures and inclination angles. A series of Computational Fluid Dynamics (CFD) simulations based on a prototypical cold tip was carried out. Detailed CFD model predictions were compared with the experiment and were used to investigate the impact of such apparently minor geometric imperfections on the performance of Stirling type pulse tube cryocoolers. Predictions of cooling performance and gravity orientation sensitivity were compared with experimental results obtained with the cryocooler prototypes. The results indicate that minor geometry features in the cold tip assembly can have considerable negative effects on the gravity orientation sensitivity of a pulse tube cryocooler.

  9. Engineering model cryocooler test results

    International Nuclear Information System (INIS)

    Skimko, M.A.; Stacy, W.D.; McCormick, J.A.

    1992-01-01

    This paper reports that recent testing of diaphragm-defined, Stirling-cycle machines and components has demonstrated cooling performance potential, validated the design code, and confirmed several critical operating characteristics. A breadboard cryocooler was rebuilt and tested from cryogenic to near-ambient cold end temperatures. There was a significant increase in capacity at cryogenic temperatures and the performance results compared will with code predictions at all temperatures. Further testing on a breadboard diaphragm compressor validated the calculated requirement for a minimum axial clearance between diaphragms and mating heads

  10. Sorption by cation exchange

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1994-04-01

    A procedure for introducing exchange into geochemical/surface complexation codes is described. Beginning with selectivity coefficients, K c , defined in terms of equivalent fractional ion occupancies, a general expression for the molar based exchange code input parameters, K ex , is derived. In natural systems the uptake of nuclides onto complex sorbents often occurs by more than one mechanism. The incorporation of cation exchange and surface complexation into a geochemical code therefore enables sorption by both mechanisms to be calculated simultaneously. The code and model concepts are tested against sets of experimental data from widely different sorption studies. A proposal is made to set up a data base of selectivity coefficients. Such a data base would form part of a more general one consisting of sorption mechanism specific parameters to be used in conjunction with geochemical/sorption codes to model and predict sorption. (author) 6 figs., 6 tabs., 26 refs

  11. Particle-size dependent sorption and desorption of pesticides within a water-soil-nonionic surfactant system.

    Science.gov (United States)

    Wang, Peng; Keller, Arturo A

    2008-05-01

    Although nonionic surfactants have been considered in surfactant-aided soil washing systems, there is little information on the particle-size dependence of these processes, and this may have significant implications for the design of these systems. In this study, Triton-100 (TX) was selected to study its effect on the sorption and desorption of two pesticides (Atrazine and Diuron) from different primary soil size fractions (clay, silt, and sand fractions) under equilibrium sorption and sequential desorption. Soil properties, TX sorption, and pesticide sorption and desorption all exhibited significant particle-size dependence. The cation exchange capacity (CEC) of the bulk soils and the soil fractions determined TX sorption capacity, which in turn determined the desorption efficiency. Desorption of pesticide out of the clay raction is the limiting factor in a surfactant-aided washing system. The solubilization efficiency of the individual surfactant micelles decreased as the amount of surfactant added to the systems increased. Thus, instead of attempting to wash the bulk soil, a better strategy might be to either (1) use only the amount of surfactant that is sufficient to clean the coarse fraction, then separate the fine fraction, and dispose or treat it separately, or (2) to separate the coarse fractions mechanically and then treatthe coarse and fine fractions separately. These results may be applicable to many other hydrophobic organic compounds such as polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) strongly sorbed onto soils and sediments.

  12. Dispersion, sorption and photodegradation of petroleum hydrocarbons in dispersant-seawater-sediment systems.

    Science.gov (United States)

    Zhao, Xiao; Liu, Wen; Fu, Jie; Cai, Zhengqing; O'Reilly, S E; Zhao, Dongye

    2016-08-15

    This work examined effects of model oil dispersants on dispersion, sorption and photodegradation of petroleum hydrocarbons in simulated marine systems. Three dispersants (Corexit 9500A, Corexit 9527A and SPC 1000) were used to prepare dispersed water accommodated oil (DWAO). While higher doses of dispersants dispersed more n-alkanes and PAHs, Corexit 9500A preferentially dispersed C11-C20 n-alkanes, whereas Corexit 9527A was more favorable for smaller alkanes (C10-C16), and SPC 1000 for C12-C28 n-alkanes. Sorption of petroleum hydrocarbons on sediment was proportional to TPH types/fractions in the DWAOs. Addition of 18mg/L of Corexit 9500A increased sediment uptake of 2-3 ring PAHs, while higher dispersant doses reduced the uptake, due to micelle-enhanced solubilization effects. Both dispersed n-alkanes and PAHs were susceptible to photodegradation under simulated sunlight. For PAHs, both photodegradation and photo-facilitated alkylation were concurrently taking place. The information can facilitate sounder assessment of fate and distribution of dispersed oil hydrocarbons in marine systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Advanced cryocooler electronics for space

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, D.; Danial, A.; Godden, J.; Jackson, M.; McCuskey, J.; Valenzuela, P. [Northrop Grumman Space Technology, Redondo Beach, CA (United States); Davis, T. [Air Force Research Lab., Albuquerque, NM (United States)

    2004-08-01

    Space pulse-tube cryocoolers require electronics to control the cooling temperature and self-induced vibration. Other functions include engineering diagnostics, telemetry and safety protection of the unit against extreme environments and operational anomalies. The electronics must survive the harsh conditions of launch and orbit, and in some cases severe radiation environments for periods exceeding 10 years. A number of our current generation high reliability radiation hardened electronics units have been launched and others are in various stages of assembly or integration on a number of space flight programs. This paper describes the design features and performance of our next generation flight electronics designed for the STSS payloads. The electronics provides temperature control with better than +/-50 mK short-term stability. Self-induced vibration is controlled to low levels on all harmonics up to the 16th. A unique active power filter limits peak-to-peak reflected ripple current on the primary power bus to less than 3% of the average DC current. The 3 kg unit is capable of delivering 180 W continuous to NGST's high-efficiency cryocooler (HEC). (author)

  14. Geoelectrical Monitoring of Ammonium Sorption Processes in a Biochar Filtration System

    Science.gov (United States)

    Wang, S. L.; Osei, C.; Rabinovich, A.; Ntarlagiannis, D.; Rouff, A.

    2017-12-01

    With the rise of modern agriculture, nutrient pollution has become an increasingly important environmental concern. A common problem is excess nitrogen which agricultural livestock farms often generate in the form of ammonium (NH4+). This highly soluble ion is easily transported through runoff and leaching, leading to water supply contamination and soil fertility decline. Biochar is the carbon-rich product of thermal decomposition of biomass in an oxygen-free environment. It is primarily used as a soil enhancer with other applications currently under research. Biochar's unique characteristics such as high surface area, high sorption capacity and long term biological and chemical stability make it a prime candidate for environmental applications such as contaminant regulation and waste effluent treatment. The spectral induced polarization (SIP) method is an established geoelectrical method that has been increasingly used in environmental investigations. SIP is unique among geophysical methods because it is sensitive not only to the bulk properties of the medium under investigation but also to the interfacial properties (e.g., mineral-fluid). The unique properties that make biochar attractive for environmental use are associated with surface properties (e.g., surface area, surface charge, presence of functional groups) that are expected to have a profound effect on SIP signals. This study presents early results on the use of the SIP method to monitor ammonium recycling of swine wastewater in a biochar filtration system. SIP measurements were taken continuously as biochar-packed columns were first injected with an ammonium wastewater solution (sorption phase) and then an ammonium-free solution (desorption phase). Geochemical monitoring showed that outflow ammonium concentration decreased during the sorption phase and increased during the desorption phase. The collected SIP data appear to be in agreement with the geochemical monitoring, providing a temporally

  15. Study of plutonium sorption in aluminia column in the system HNO3-HF

    International Nuclear Information System (INIS)

    Araujo, J.A. de.

    1977-01-01

    The column chromatographic method using alumina has been applied successfully to study the sorption-desorption behavior of plutonium traces in HNO 3 -HF and HNO 3 -HF-UO 2 (NO 3 ) 2 systems, aiming to elaborate a process for recovering plutonium traces from reprocessing wastes, mainly in existing solutions where uranium is presented in macro quantities. Basically, the method consists in the sorption of plutonium by percolating a solution containing HNO 3 (0,1 to 0,8M) or uranyl nitrate (1-50 gU/l) and HF(0,1 to 0,3M) through an Al 2 O 3 collumn. The plutonium is fixed on Al 2 O 3 whereas the uranyl ions is collected in the efluent. The adsorption of Pu-III, Pu-IV and Pu-VI in the presence of HF was determined and Pu-IV can be almost completely sorbed. The Pu-IV is eluted by reduction to Pu-III in the column using 3 M HNO 3 -0,005M FeSO 4 at 50 0 C as elutrient. This method is very simple and can be applied for separation and purification of plutonium (traces) from uranyl nitrate or others coming solutions from wet chemistry of irradiated fuels [pt

  16. A miniature pulse tube cryocooler used in a superspectral imager

    Science.gov (United States)

    Jiang, Zhenhua; Wu, Yinong

    2017-05-01

    In this paper, we describe a hihg0 frequency pulse tube cryocooler used in a superspectral imager to be launched in 2020. The superspectral imager is a field-dividing optical imaging system and uses 14 sets of integrated IR detector cryocooler dewar assembly. For the requirements of less heat loss an smaller size, each set is highly integrated by directly mounting the IR dectector's sapphire substrate on the pulse tube's cold tip, and welding the dewar's housing to the flange of the cold finger. Driven by a pair of moving magnet linear motors, the dual-opposed piston compressor of the croycooler is running at 120Hz. Filled with customized stainless screens in the regenerator, the cryolooler reaches 8.1% carnot efficiency at the cooling power of 1W@80K with 34Wac input power.

  17. Compact cryocooler heat exchangers

    International Nuclear Information System (INIS)

    Luna, J.; Frederking, T.H.K.

    1991-01-01

    Compact heat exchangers are subject to different constraints as a room temperature gas is cooled down by a cold stream returning from a JT valve (or a similar cryoprocess component). In particular, the optimization of exchangers for liquid helium systems has to cover a wide range in temperature and density of the fluid. In the present work we address the following thermodynamic questions: 1. The optimization of intermediate temperatures which optimize stage operation (a stage is assumed to have a constant cross section); 2. The optimum temperature difference available for best overall economic performance values. The results are viewed in the context of porous media concepts applied to rather low speeds of fluid flow in narrow passages. In this paper examples of fluid/solid constraints imposed in this non-classical low temperature area are presented

  18. Raytheon Stirling/pulse Tube Cryocooler Development

    Science.gov (United States)

    Kirkconnell, C. S.; Hon, R. C.; Kesler, C. H.; Roberts, T.

    2008-03-01

    The first generation flight-design Stirling/pulse tube "hybrid" two-stage cryocooler has entered initial performance and environmental testing. The status and early results of the testing are presented. Numerous improvements have been implemented as compared to the preceding brassboard versions to improve performance, extend life, and enhance launch survivability. This has largely been accomplished by incorporating successful flight-design features from the Raytheon Stirling one-stage cryocooler product line. These design improvements are described. In parallel with these mechanical cryocooler development efforts, a third generation electronics module is being developed that will support hybrid Stirling/pulse tube and Stirling cryocoolers. Improvements relative to the second generation design relate to improved radiation hardness, reduced parts count, and improved vibration cancellation capability. Progress on the electronics is also presented.

  19. Sorption Characteristics of Sediments in the Upper Mississippi River System Above Lake Pepin

    National Research Council Canada - National Science Library

    James, W

    1999-01-01

    This technical note examines equilibrium phosphorus processes and sorption characteristics for sediments collected from the Minnesota River, immediately upstream from its confluence with the Upper Mississippi River (UMR...

  20. Fate of cocaine drug biomarkers in sewer system: the role of suspended solids in biotransformation and sorption

    DEFF Research Database (Denmark)

    Ramin, Pedram; Brock, Andreas Libonati; Polesel, Fabio

    on the fate of illicit drugs in sewer systems. This study aims at assessing the role of suspended solids on the biotransformation and sorption in raw sewage of eight illicit drug biomarkers (cocaine, heroin, methadone, mephedrone, ketamine, methamphetamine, MDMA and THC and their urinary metabolites...

  1. Design and component test performance of an efficient 4 W, 130 K sorption refrigerator

    International Nuclear Information System (INIS)

    Alvarez, J.; Ryba, E.; Sywulka, P.; Wade, L.

    1990-01-01

    A recent advance in sorption cooler technology has resulted in cryocooler designs offering high performance and the promise of long-life operation. A 4-W, 130 K sorption refrigeration stage which incorporates the advanced concept design is presently being constructed. Powdered charcoal is used as the sorbent, and methane is used as the refrigerant. Expansion is accomplished using a passive Joule-Thomson expansion valve. The design details of this cooler and the component performance test results are discussed. 5 refs

  2. Modelling the fate of ciprofloxacin in activated sludge systems - The relevance of the sorption process

    DEFF Research Database (Denmark)

    Polesel, Fabio; Lehnberg, Kai; Dott, Wolfgang

    The sorption process can impact the removal of specific pharmaceuticals in municipal wastewater treatment plants (WWTPs). Ionic interactions (e.g., pH-driven equilibria and complexation), rather than hydrophobic interactions, are known to affect the sorption of zwitterionic pharmaceuticals...

  3. Energy density and storage capacity cost comparison of conceptual solid and liquid sorption seasonal heat storage systems for low-temperature space heating

    NARCIS (Netherlands)

    Scapino, L.; Zondag, H.A.; Van Bael, J.; Diriken, J.; Rindt, C.C.M.

    Sorption heat storage can potentially store thermal energy for long time periods with a higher energy density compared to conventional storage technologies. A performance comparison in terms of energy density and storage capacity costs of different sorption system concepts used for seasonal heat

  4. Analytical and experimental investigation of closed-cycle sorption cooling systems

    Science.gov (United States)

    Liu, Lianquan

    1992-01-01

    The first part of the present thesis concerns the Coefficient of Performance (COP) of two types of closed-cycle sorption cooling systems: the Single Effect Liquid (SEL) absorption system and the Regenerative Solid (RS) adsorption system. When specific cycle configurations are considered, the COP is always less than that allowed by the second law. The potential of the two systems to approach the second law limit is considered in this work. The analysis shows that COP of a SEL system using LiBr-H2O is not limited by one, as believed before, and that the COP of a RS cooling system using zeolite-water is considerably larger than that of the SEL system. This is due to recovery of the heat of adsorption which is made possible by capturing the thermal wave in the solid adsorbent. In the second part, a one dimensional model has been developed for a real RS cooling system featured by finite heat transfer coefficients. The problem is solved numerically to yield the temperature and uptake profiles, COP, and cooling capacity and cooling rates. The effects of various design and operating parameters on system performance have been investigated by using the model. The convective heat transfer coefficient at the inner wall of the fluid channel passing through the zeolite columns, the flow rate of the heat transfer fluid, the condenser and evaporator temperature are identified as the most significant factors. A new correlation of adsorption equilibrium has been derived in this thesis. The derivation is based on established thermodynamic relationships and is shown to be able to well represent the data of three adsorption pairs widely used in sorption cooling applications: zeolite-water, silica gel-water and activated carbon-methanol. Finally, in the experimental part of the present work a test set-up of a zeolite-water heat and mass regenerator was designed, instrumented and built. Temperature profiles at various operating conditions were measured. The data of a 'single blow' mode

  5. Sorption mechanisms and sorption models

    International Nuclear Information System (INIS)

    Fedoroff, M.; Lefevre, G.; Duc, M.; Neskovic, C.; Milonjic, S.

    2004-01-01

    Sorption at the solid-liquid interfaces play a major role in many phenomena and technologies: chemical separations, catalysis, biological processes, transport of toxic and radioactive species in surface and underground waters. The long term safety of radioactive waste repositories is based on artificial and natural barriers, intended to sorb radionuclides after the moment when the storage matrixes and containers will be corroded. Predictions on the efficiency of sorption for more than 10 6 years have to be done in order to demonstrate the safety of such depositories, what is a goal never encountered in the history of sciences and technology. For all these purposes, and, especially for the long term prediction, acquiring of sorption data constitutes only a first step of studies. Modeling based on a very good knowledge of sorption mechanisms is needed. In this review, we shall examine the main approaches and models used to quantify sorption processes, including results taken from the literature and from our own studies. We shall compare sorption models and examine their adequacy with sorption mechanisms. The cited references are only a few examples of the numerous articles published in that field. (orig.)

  6. Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

    Science.gov (United States)

    Chang, Ho-Myung; Park, Chan Woo; Yang, Hyung Suk; Hwang, Si Dole

    2014-01-01

    Dynamic simulation of a Brayton cryocooler is presented as a partial effort of a Korean governmental project to develop 1˜3 km HTS cable systems at transmission level in Jeju Island. Thermodynamic design of a 10 kW Brayton cryocooler was completed, and a prototype construction is underway with a basis of steady-state operation. This study is the next step to investigate the transient behavior of cryocooler for two purposes. The first is to simulate and design the cool-down process after scheduled or unscheduled stoppage. The second is to predict the transient behavior following the variation of external conditions such as cryogenic load or outdoor temperature. The detailed specifications of key components, including plate-fin heat exchangers and cryogenic turbo-expanders are incorporated into a commercial software (Aspen HYSYS) to estimate the temporal change of temperature and flow rate over the cryocooler. An initial cool-down scenario and some examples on daily variation of cryocooler are presented and discussed, aiming at stable control schemes of a long cable system.

  7. Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

    International Nuclear Information System (INIS)

    Chang, Ho-Myung; Park, Chan Woo; Yang, Hyung Suk; Hwang, Si Dole

    2014-01-01

    Dynamic simulation of a Brayton cryocooler is presented as a partial effort of a Korean governmental project to develop 1∼3 km HTS cable systems at transmission level in Jeju Island. Thermodynamic design of a 10 kW Brayton cryocooler was completed, and a prototype construction is underway with a basis of steady-state operation. This study is the next step to investigate the transient behavior of cryocooler for two purposes. The first is to simulate and design the cool-down process after scheduled or unscheduled stoppage. The second is to predict the transient behavior following the variation of external conditions such as cryogenic load or outdoor temperature. The detailed specifications of key components, including plate-fin heat exchangers and cryogenic turbo-expanders are incorporated into a commercial software (Aspen HYSYS) to estimate the temporal change of temperature and flow rate over the cryocooler. An initial cool-down scenario and some examples on daily variation of cryocooler are presented and discussed, aiming at stable control schemes of a long cable system

  8. Dynamic simulation of 10 kW Brayton cryocooler for HTS cable

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Ho-Myung; Park, Chan Woo [Hong Ik University, Department of Mechanical Engineering, Seoul, 121-791 (Korea, Republic of); Yang, Hyung Suk; Hwang, Si Dole [KEPCO Research Institute, Daejeon, 305-760 (Korea, Republic of)

    2014-01-29

    Dynamic simulation of a Brayton cryocooler is presented as a partial effort of a Korean governmental project to develop 1∼3 km HTS cable systems at transmission level in Jeju Island. Thermodynamic design of a 10 kW Brayton cryocooler was completed, and a prototype construction is underway with a basis of steady-state operation. This study is the next step to investigate the transient behavior of cryocooler for two purposes. The first is to simulate and design the cool-down process after scheduled or unscheduled stoppage. The second is to predict the transient behavior following the variation of external conditions such as cryogenic load or outdoor temperature. The detailed specifications of key components, including plate-fin heat exchangers and cryogenic turbo-expanders are incorporated into a commercial software (Aspen HYSYS) to estimate the temporal change of temperature and flow rate over the cryocooler. An initial cool-down scenario and some examples on daily variation of cryocooler are presented and discussed, aiming at stable control schemes of a long cable system.

  9. Tactical versus space cryocoolers: a comparision

    Science.gov (United States)

    Arts, R.; Mullié, J.; Leenders, H.; de Jonge, G.; Benschop, T.

    2017-05-01

    In recent years, several space cryocooler developments have been performed in parallel at Thales Cryogenics. On one end of the spectrum are research programmes such as the ESA-funded 30-50 K system developed in cooperation with CEA and Absolut System and the LPT6510 cooler developed in cooperation with Absolut System. On the other end of the spectrum are commercial designs adapted for space applications, such as the LPT9310 commercial coolers delivered for JPL's ECOSTRESS instrument and the LSF9199/30 SADA-compatible cooler delivered for various space programmes at Sofradir. In this paper, an overview is presented of the latest developments regarding these coolers. Initial performance results of the 30-50K cooler are discussed, pending developments for the LPT6510 cooler are presented, and the synergies between COTS and space are reviewed, such as design principles from space coolers being applied to an upgraded variant of the COTS LPT9310, as well as design principles from COTS coolers being applied to the LPT6510 for improved manufacturability.

  10. Raytheon's next generation compact inline cryocooler architecture

    International Nuclear Information System (INIS)

    Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T.

    2014-01-01

    Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (≤25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing

  11. Raytheon's next generation compact inline cryocooler architecture

    Science.gov (United States)

    Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T.

    2014-01-01

    Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (≤25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing

  12. Experimental study on an innovative multifunction heat pipe type heat recovery two-stage sorption refrigeration system

    International Nuclear Information System (INIS)

    Li, T.X.; Wang, R.Z.; Wang, L.W.; Lu, Z.S.

    2008-01-01

    An innovative multifunction heat pipe type sorption refrigeration system is designed, in which a two-stage sorption thermodynamic cycle based on two heat recovery processes was employed to reduce the driving heat source temperature, and the composite sorbent of CaCl 2 and activated carbon was used to improve the mass and heat transfer performances. For this test unit, the heating, cooling and heat recovery processes between two reactive beds are performed by multifunction heat pipes. The aim of this paper is to investigate the cycled characteristics of two-stage sorption refrigeration system with heat recovery processes. The two sub-cycles of a two-stage cycle have different sorption platforms though the adsorption and desorption temperatures are equivalent. The experimental results showed that the pressure evolutions of two beds are nearly equivalent during the first stage, and desorption pressure during the second stage is large higher than that in the first stage while the desorption temperatures are same during the two operation stages. In comparison with conventional two-stage cycle, the two-stage cycle with heat recovery processes can reduce the heating load for desorber and cooling load for adsorber, the coefficient of performance (COP) has been improved more than 23% when both cycles have the same regeneration temperature of 103 deg. C and the cooling water temperature of 30 deg. C. The advanced two-stage cycle provides an effective method for application of sorption refrigeration technology under the condition of low-grade temperature heat source or utilization of renewable energy

  13. Role of size on the relative importance of fluid dynamic losses in linear cryocoolers

    Science.gov (United States)

    Kirkconnell, Carl; Ghavami, Ali; Ghiaasiaan, S. Mostafa; Perrella, Matthew

    2017-12-01

    Thermodynamic modeling results for a novel small satellite (SmallSat) Stirling Cryocooler, capable of delivering over 200 mW net cooling power at 80 K for less than 6 W DC input power, are used in this paper as the basis for related pulse tube computational fluid dynamics (CFD) analysis. Industry and government requirements for SmallSat infrared sensors are driving the development of ever-more miniaturized cryocooler systems. Such cryocoolers must be extremely compact and lightweight, a challenge met by this research team through operating a Stirling cryocooler at a frequency of approximately 300 Hz. The primary advantage of operating at such a high frequency is that the required compression and expansion swept volumes are reduced relative to linear coolers operating at lower frequencies, which evidently reduces the size of the motor mechanisms and the thermodynamic components. In the case of a pulse tube cryocooler, this includes a reduction in diameter of the pulse tube itself. This unfortunately leads to high boundary layer losses, as the presented results demonstrate. Using a Stirling approach with a mechanical moving expander piston eliminates this small pulse tube loss mechanism, but other challenges are introduced, such as maintaining very tight clearance gaps between moving and stationary elements. This paper focuses on CFD modelling results for a highly miniaturized pulse tube cooler.

  14. Cryocooled superconducting magnets for high magnetic fields at the HFLSM and future collaboration with the TML

    International Nuclear Information System (INIS)

    Watanabe, K; Nishijima, G; Awaji, S; Koyama, K; Takahashi, K; Kobayashi, N; Kiyoshi, T

    2006-01-01

    A hybrid magnet needs a large amount of liquid helium for operation. In order to make an easy-to-operate hybrid magnet system, we constructed a cryocooled 28 T hybrid magnet, consisting of an outer cryocooled 10 T superconducting magnet and an inner traditional water-cooled 19 T resistive magnet. As a performance test, the cryocooled hybrid magnet generated 27.5 T in a 32 mm room temperature experimental bore. As long as Nb3Sn superconducting wires are employed, the expected maximum high field generation in the cryocooled superconducting magnet will be 17 T at 5 K. We adopted the high temperature superconducting insert coil, employing Ag-sheathed Bi 2 Sr 2 Ca 2 Cu 3 O 10 superconducting tape. In combination with the low temperature 16.5 T back-up coil with a 174 mm cold bore, the cryocooled high temperature superconducting magnet successfully generated the total central field of 18.1 T in a 52 mm room temperature bore. As a next step, we start the collaboration with the National Institute for Materials Science for the new developmental works of a 30 T high temperature superconducting magnet and a 50 T-class hybrid magnet

  15. Development of 1 kW Stirling cryocooler using a linear compressor

    International Nuclear Information System (INIS)

    Ko, J; Kim, H; Hong, Y J; Yeom, H; In, S; Park, S J

    2015-01-01

    Cryogenic cooling systems for HTS electric power devices require a reliable and efficient high-capacity cryocooler. A Striling cryocooler with a linear compressor can be a good candidate. It has advantages of low vibration and long maintenance cycle compared with a kinematic-driven Stirling cryocooler. In this study, we developed a dual-opposed linear compressor of 12 kW electric input power with two 6 kW linear motors. Electrical performance of the fabricated linear compressor is verified by experimental measurement of thrust constant. The developed Stirling cryocooler has a gamma-type configuration. The piston and displacer are supported with a flexure spring. A slit-type heat exchanger is adopted for the cold and warm-end, and the generated heat is rejected by cooling water. In the cooling performance test, waveforms of voltage, current, displacement and pressure are obtained and their amplitude and phase difference are analysed. The developed cryocooler reaches 47.8 K within 23.4 min. with no-load. Heat load tests shows a cooling capacity of 440 W at 78.1 K with 6.45 kW of electric input power and 19.4 of % Carnot COP. (paper)

  16. Role of soil micro-organisms in the sorption of radionuclides in organic systems

    International Nuclear Information System (INIS)

    Parekh, N.R.; Potter, E.D.; Poskitt, J.M.; Dodd, B.A.; Sanchez, A.

    2004-01-01

    Although the fraction of radionuclides linked to soil organic matter and soil microorganisms may be relatively small when compared to the amount bound to the mineral constituents, (mostly irreversibly bound), this fraction is of great importance as it remains readily exchangeable and is thus available for plant uptake. Many studies have measured the uptake of radionuclides by organic soils but the role of soil micro-organisms may have been masked by the presence of even small amounts of clay minerals occurring in these soils. We have carried out a series of experiments using a biologically active, 'mineral-free' organic soil produced under laboratory conditions, to determine the potential of soil micro-organisms to accumulate radionuclides Cs-134 and Sr-85. Biological uptake and release was differentiated from abiotic processes by comparing experimental results with inoculated and non-inoculated sterile organic material. We have investigated the role of different clay minerals, competing potassium and calcium ions, and changes in temperature on the sorption of Cs and Sr isotopes. The results from studies so far show conclusively that living components of soil systems are of primary importance in the uptake of radionuclides in organic material, microorganisms also influence the importance of chemical factors (e.g. adsorption to clay minerals) which may play a secondary role in these highly organic systems. In further experiments we hope to define the precise role of specific soil micro-organisms in these organic systems. (author)

  17. Radionuclide distributions and sorption behavior in the Susquehanna--Chesapeake Bay System

    International Nuclear Information System (INIS)

    Olsen, C.R.; Larsen, I.L.; Lowry, P.D.; McLean, R.I.; Domotor, S.L.

    1989-01-01

    Radionuclides released into the Susquehanna--Chesapeake System from the Three Mile Island, Peach Bottom, and Calvert Cliffs nuclear power plants are partitioned among dissolved, particulate, and biological phases and may thus exist in a number of physical and chemical forms. In this project, we have measured the dissolved and particulate distributions of fallout 137 Cs; reactor-released 137 Cs, 134 Cs, 65 Zn, 60 Co, and 58 Co; and naturally occurring 7 Be and 210 Pb in the lower Susquehanna River and Upper Chesapeake Bay. In addition, we chemically leached suspended particles and bottom sediments in the laboratory to determine radionuclide partitioning among different particulate-sorbing phases to complement the site-specific field data. This information has been used to document the important geochemical processes that affect the transport, sorption, distribution, and fate of reactor-released radionuclides (and by analogy, other trace contaminants) in this river-estuarine system. Knowledge of the mechanisms, kinetic factors, and processes that affect radionuclide distributions is crucial for predicting their biological availability, toxicity, chemical behavior, physical transport, and accumulation in aquatic systems. The results from this project provide the information necessary for developing accurate radionuclide-transport and biological-uptake models. 76 refs., 12 figs

  18. Characterizing pesticide sorption and degradation in microscale biopurification systems using column displacement experiments

    International Nuclear Information System (INIS)

    Wilde, Tineke de; Mertens, Jan; Simunek, Jirka; Sniegowksi, Kristel; Ryckeboer, Jaak; Jaeken, Peter; Springael, Dirk; Spanoghe, Pieter

    2009-01-01

    Biopurification systems treating pesticide contaminated water are very efficient, however they operate as a black box. Processes inside the system are not yet characterized. To optimize the performance, knowledge of degradation and retention processes needs to be generated. Therefore, displacement experiments were carried out for four pesticides (isoproturon, bentazone, metalaxyl, linuron) in columns containing different organic mixtures. Bromide, isoproturon and bentazone breakthrough curves (BTCs) were well described using the convection-dispersion equation (CDE) and a first-order degradation kinetic approach. Metalaxyl and linuron BTCs were well described using the CDE model expanded with Monod-type kinetics. Freundlich sorption, first-order degradation and Monod kinetics coefficients were fitted to the BTCs. Fitted values of the distribution coefficient K f,column were much lower than those determined from batch experiments. Based on mobility, pesticides were ranked as: bentazone > metalaxyl - isoproturon > linuron. Based on degradability, pesticides were ranked as: linuron > metalaxyl - isoproturon > bentazone. - Transport of pesticides in column experiments containing organic substrates

  19. Characterizing pesticide sorption and degradation in microscale biopurification systems using column displacement experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wilde, Tineke de [Laboratory of Crop Protection Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium)], E-mail: tineke.dewilde@UGent.be; Mertens, Jan [Division Soil and Water Management, Faculty of Bioscience Engineering, K.U. Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee (Belgium); Simunek, Jirka [Department of Environmental Sciences, University of California, Riverside, CA (United States); Sniegowksi, Kristel; Ryckeboer, Jaak [Division Soil and Water Management, Faculty of Bioscience Engineering, K.U. Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee (Belgium); Jaeken, Peter [PCF-Royal Research Station of Gorsem, De Brede Akker 13, 3800 Sint-Truiden (Belgium); Springael, Dirk [Division Soil and Water Management, Faculty of Bioscience Engineering, K.U. Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee (Belgium); Spanoghe, Pieter [Laboratory of Crop Protection Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium)

    2009-02-15

    Biopurification systems treating pesticide contaminated water are very efficient, however they operate as a black box. Processes inside the system are not yet characterized. To optimize the performance, knowledge of degradation and retention processes needs to be generated. Therefore, displacement experiments were carried out for four pesticides (isoproturon, bentazone, metalaxyl, linuron) in columns containing different organic mixtures. Bromide, isoproturon and bentazone breakthrough curves (BTCs) were well described using the convection-dispersion equation (CDE) and a first-order degradation kinetic approach. Metalaxyl and linuron BTCs were well described using the CDE model expanded with Monod-type kinetics. Freundlich sorption, first-order degradation and Monod kinetics coefficients were fitted to the BTCs. Fitted values of the distribution coefficient K{sub f,column} were much lower than those determined from batch experiments. Based on mobility, pesticides were ranked as: bentazone > metalaxyl - isoproturon > linuron. Based on degradability, pesticides were ranked as: linuron > metalaxyl - isoproturon > bentazone. - Transport of pesticides in column experiments containing organic substrates.

  20. Design and development of a four-cell sorption compressor based J-T cooler using R134a as working fluid

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, R. N. [Mechanical Engineering Department, Indian Institute of Technology Bombay, Mumbai - 400076, India and Government Engineering College Bharuch, Gujarat - 392002 (India); Bapat, S. L.; Atrey, M. D. [Mechanical Engineering Department, Indian Institute of Technology Bombay, Mumbai - 400076 (India)

    2014-01-29

    The need of a cooler with no electromagnetic interference and practically zero vibration has led to sorption compressor based Joule-Thomson (J-T) coolers. These are useful for sophisticated electronic, ground based and space borne systems. In a Sorption compressor, adsorbed gases are desorbed into a confined volume by raising temperature of the sorption bed resulting in an increase in pressure of the liberated gas. In order to have the system (compressor) functioning on a continuous basis, with almost a constant gas flow rate, multiple cells are used with the adaptation of Temperature Swing Adsorption (TSA) process. As the mass of the desorbed gas dictates the compressor throughput, a combination of sorbent material with high adsorption capacity for a chosen gas or gas mixture has to be selected for efficient operation of the compressor. Commercially available (coconut-shell base) activated carbon has been selected for the present application. The characterization study for variation of discharge pressure is used to design the Four-cell sorption compressor based cryocooler with a desired output. Apart from compressor, the system includes a) After cooler b) Return gas heat exchanger c) capillary tube as the J-T expansion device and d) Evaporator.

  1. Sorption data bases and mechanistic sorption studies

    International Nuclear Information System (INIS)

    Bradbury, M.H.

    2000-01-01

    In common with many other countries with a nuclear programme, the Swiss concept for the disposal of radioactive waste is focused on deep burial in specially constructed repositories in geologically stable host rocks. Under such conditions, the most likely means whereby radionuclides might return to the biosphere involves their transport in slowly moving groundwater. The sorption of radionuclides by solid phases in the engineered barriers within the repository, and in the surrounding geological media, limits their release and retards their movement. Performance assessment studies for disposal concepts are carried out by Nagra, the National Cooperative for the Disposal of Radioactive Waste, in which various release scenarios are examined, and 'doses to man' calculated. The uptake of radionuclides by immobile phases is one of the pillars upon which the safety case rests. Hence, sorption databases are very important data sets for performance assessments. The methodology lying behind the construction of sorption databases, and some aspects of the supporting experimental work, are briefly described in this report. Flexible, long-term, focused research programmes are required to properly understand the radionuclide/rock/groundwater system, and this is an essential pre-requisite for producing robust state-of-the-art sorption databases. (author)

  2. Sorption data bases and mechanistic sorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, M.H

    2000-07-01

    In common with many other countries with a nuclear programme, the Swiss concept for the disposal of radioactive waste is focused on deep burial in specially constructed repositories in geologically stable host rocks. Under such conditions, the most likely means whereby radionuclides might return to the biosphere involves their transport in slowly moving groundwater. The sorption of radionuclides by solid phases in the engineered barriers within the repository, and in the surrounding geological media, limits their release and retards their movement. Performance assessment studies for disposal concepts are carried out by Nagra, the National Cooperative for the Disposal of Radioactive Waste, in which various release scenarios are examined, and 'doses to man' calculated. The uptake of radionuclides by immobile phases is one of the pillars upon which the safety case rests. Hence, sorption databases are very important data sets for performance assessments. The methodology lying behind the construction of sorption databases, and some aspects of the supporting experimental work, are briefly described in this report. Flexible, long-term, focused research programmes are required to properly understand the radionuclide/rock/groundwater system, and this is an essential pre-requisite for producing robust state-of-the-art sorption databases. (author)

  3. A review of the distribution coefficients of trace elements in soils: influence of sorption system, element characteristics, and soil colloidal properties.

    Science.gov (United States)

    Shaheen, Sabry M; Tsadilas, Christos D; Rinklebe, Jörg

    2013-12-01

    Knowledge about the behavior and reactions of separate soil components with trace elements (TEs) and their distribution coefficients (Kds) in soils is a key issue in assessing the mobility and retention of TEs. Thus, the fate of TEs and the toxic risk they pose depend crucially on their Kd in soil. This article reviews the Kd of TEs in soils as affected by the sorption system, element characteristics, and soil colloidal properties. The sorption mechanism, determining factors, favorable conditions, and competitive ions on the sorption and Kd of TEs are also discussed here. This review demonstrates that the Kd value of TEs does not only depend on inorganic and organic soil constituents, but also on the nature and characteristics of the elements involved as well as on their competition for sorption sites. The Kd value of TEs is mainly affected by individual or competitive sorption systems. Generally, the sorption in competitive systems is lower than in mono-metal sorption systems. More strongly sorbed elements, such as Pb and Cu, are less affected by competition than mobile elements, such as Cd, Ni, and Zn. The sorption preference exhibited by soils for elements over others may be due to: (i) the hydrolysis constant, (ii) the atomic weight, (iii) the ionic radius, and subsequently the hydrated radius, and (iv) its Misono softness value. Moreover, element concentrations in the test solution mainly affect the Kd values. Mostly, values of Kd decrease as the concentration of the included cation increases in the test solution. Additionally, the Kd of TEs is controlled by the sorption characteristics of soils, such as pH, clay minerals, soil organic matter, Fe and Mn oxides, and calcium carbonate. However, more research is required to verify the practical utilization of studying Kd of TEs in soils as a reliable indicator for assessing the remediation process of toxic metals in soils and waters. © 2013 Elsevier B.V. All rights reserved.

  4. Heterogeneous carbonaceous matter in sedimentary rock lithocomponents causes significant trichloroethylene (TCE) sorption in a low organic carbon content aquifer/aquitard system.

    Science.gov (United States)

    Choung, Sungwook; Zimmerman, Lisa R; Allen-King, Richelle M; Ligouis, Bertrand; Feenstra, Stanley

    2014-10-15

    This study evaluated the effects of heterogeneous thermally altered carbonaceous matter (CM) on trichloroethylene (TCE) sorption for a low fraction organic carbon content (foc) alluvial sedimentary aquifer and aquitard system (foc=0.046-0.105%). The equilibrium TCE sorption isotherms were highly nonlinear with Freundlich exponents of 0.46-0.58. Kerogen+black carbon was the dominant CM fraction extracted from the sediments and accounted for >60% and 99% of the total in the sands and silt, respectively. Organic petrological examination determined that the kerogen included abundant amorphous organic matter (bituminite), likely of marine origin. The dark calcareous siltstone exhibited the greatest TCE sorption among aquifer lithocomponents and accounted for most sorption in the aquifer. The results suggest that the source of the thermally altered CM, which causes nonlinear sorption, was derived from parent Paleozoic marine carbonate rocks that outcrop throughout much of New York State. A synthetic aquifer-aquitard unit system (10% aquitard) was used to illustrate the effect of the observed nonlinear sorption on mass storage potential at equilibrium. The calculation showed that >80% of TCE mass contained in the aquifer was sorbed on the aquifer sediment at aqueous concentration TCE groundwater plume in the aquifer studied. It is implied that sorption may similarly contribute to TCE persistence in other glacial alluvial aquifers with similar geologic characteristics, i.e., comprised of sedimentary rock lithocomponents that contain thermally altered CM. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Effects of solvent evaporation on water sorption/solubility and nanoleakage of adhesive systems.

    Science.gov (United States)

    Chimeli, Talita Baumgratz Cachapuz; D'Alpino, Paulo Henrique Perlatti; Pereira, Patrícia Nóbrega; Hilgert, Leandro Augusto; Di Hipólito, Vinicius; Garcia, Fernanda Cristina Pimentel

    2014-01-01

    To evaluate the influence of solvent evaporation in the kinetics of water diffusion (water sorption-WS, solubility-SL, and net water uptake) and nanoleakage of adhesive systems. Disk-shaped specimens (5.0 mm in diameter x 0.8 mm in thickness) were produced (N=48) using the adhesives: Clearfil S3 Bond (CS3)/Kuraray, Clearfil SE Bond - control group (CSE)/Kuraray, Optibond Solo Plus (OS)/Kerr and Scotchbond Universal Adhesive (SBU)/3M ESPE. The solvents were either evaporated for 30 s or not evaporated (N=24/per group), and then photoactivated for 80 s (550 mW/cm2). After desiccation, the specimens were weighed and stored in distilled water (N=12) or mineral oil (N=12) to evaluate the water diffusion over a 7-day period. Net water uptake (%) was also calculated as the sum of WS and SL. Data were submitted to 3-way ANOVA/Tukey's test (α=5%). The nanoleakage expression in three additional specimens per group was also evaluated after ammoniacal silver impregnation after 7 days of water storage under SEM. Statistical analysis revealed that only the factor "adhesive" was significant (padhesives. CSE (control) presented significantly lower net uptake (5.4%). The nanoleakage was enhanced by the presence of solvent in the adhesives. Although the evaporation has no effect in the kinetics of water diffusion, the nanoleakage expression of the adhesives tested increases when the solvents are not evaporated.

  6. Chemical reactions in the bedrock-groundwater system of importance for the sorption of actinides

    International Nuclear Information System (INIS)

    Beall, G.W.; Allard, B.; Krajewski, T.; O'Kelley, G.D.

    1979-01-01

    Most suggested alternatives for deep underground disposal of high-level radioactive wastes rely upon several independent barriers like resistant canister materials, waste forms of low solubility in groundwaters and the use of back-fill material of low permeability and with nuclide retaining capacity. These barriers would retard the eventual release of radionuclides from the repository into the groundwater/bedrock system. The final and the only non-engineered barrier would be the host-rock itself. It would be desirable if the rock alone would be able to retain the long-lived radionuclides coming from the waste for long enough times to allow decay to harmless activity levels before they might reach the biosphere. The biological hazards from high-level reprocessng waste as well as from unreprocessed spent uranium fuel are dominated by the actinides and their daughter products (americium, plutonium, neptunium, thorium, radium) from about three hundred years after discharge from the reactor up to millions of years. In order to allow predictions of the migration of the actinides in the ground, the chemical behavior of these elements in groundwater under environmental conditions and their interactions with geologic media must be studied in detail. In this paper, studies of the sorption of americium (trivalent) and neptunium (pentavalent under oxic conditions) on some major rock-forming minerals of igneous rocks and accessory minerals are reported

  7. Investigation of the charge boost technology for the efficiency increase of closed sorption thermal energy storage systems

    Science.gov (United States)

    Rohringer, C.; Engel, G.; Köll, R.; Wagner, W.; van Helden, W.

    2017-10-01

    The inclusion of solar thermal energy into energy systems requires storage possibilities to overcome the gap between supply and demand. Storage of thermal energy with closed sorption thermal energy systems has the advantage of low thermal losses and high energy density. However, the efficiency of these systems needs yet to be increased to become competitive on the market. In this paper, the so-called “charge boost technology” is developed and tested via experiments as a new concept for the efficiency increase of compact thermal energy storages. The main benefit of the charge boost technology is that it can reach a defined state of charge for sorption thermal energy storages at lower temperature levels than classic pure desorption processes. Experiments are conducted to provide a proof of principle for this concept. The results show that the charge boost technology does function as predicted and is a viable option for further improvement of sorption thermal energy storages. Subsequently, a new process application is developed by the author with strong focus on the utilization of the advantages of the charge boost technology over conventional desorption processes. After completion of the conceptual design, the theoretical calculations are validated via experiments.

  8. A 1 T, 0.33 m bore superconducting magnet operating with cryocoolers at 12 K

    NARCIS (Netherlands)

    van der Laan, M.T.G.; van der Laan, M.T.G.; Tax, R.B.; ten Kate, Herman H.J.; van de Klundert, L.J.M.

    1992-01-01

    The application of small cryocoolers to cooling a superconducting magnet at 12 K has important advantages, especially for small and medium-size magnets. Simple construction and a helium-free magnet system were obtained. The demonstration magnet developed is a six-coil system with a volume of 75 L

  9. Diffusion, sorption, and retardation processes of anions in bentonite and organo-bentonites for multibarrier systems

    Science.gov (United States)

    Schampera, Birgit; Dultz, Stefan

    2013-04-01

    The low permeability, high cation exchange capacity (CEC) and plasticity of bentonites favor their use in multibarrier systems of waste deposits [1]. Bentonites have a high CEC but their ability to sorb anions is very low. There is, however, need for retardation of anions and organic pollutants in many applications. Bentonites, modified with certain organic cations, have the capacity to sorb anions and non-polar organic compounds in addition to cations. Investigations on organically modified clays address a wide variety of applications including immobilization of pollutants in contaminated soils, waste water treatment and in situ placement for the protection of ground water [2]. Many experiments on anion and cation sorption of organo-clays were conducted in the batch mode which does not reflect solid-liquid ratios and material densities in barrier systems. Diffusion experiments on compacted clays allow the evaluation of transport processes and sorption of pollutants at conditions relevant for repositories. For organo-clays only few diffusion studies are published e.g. [3] measured the diffusion of tritium and [4] the diffusion of H2O in bentonite and organo-bentonites. The organic cation hexadecylpyridinium (HDPy) was added to Wyoming bentonite (MX-80) in amounts corresponding to 2-400 % of the CEC. The uptake of organic cations was determined by the C-content, XRD and IR-spectroscopy. Wettability was analyzed by the contact angle. Physical, chemical and mineralogical properties of clays were characterized. Diffusion experiments were carried out in situ in a cell attached to the ATR-unit of a FTIR-spectrometer. For H2O-diffusion the compacted organo-clays are saturated first with D2O, afterwards H2O is supplied to the surface at the top of the clay platelet. Anion-diffusion was conducted with NO3--solution instead of H2O only having characteristic IR band positions at 1350 cm-1. Three different concentrations (0.25M, 0.5M and 1M) were used. Additional batch

  10. The mobility of indium and gallium in groundwater systems: constraining the role of sorption in sand column experiments

    Science.gov (United States)

    Dror, I.; Ringering, K.; Yecheskel, Y.; Berkowitz, B.

    2017-12-01

    The mobility of indium and gallium in groundwater environments was studied via laboratory experiments using quartz sand as a porous medium. Indium and gallium are metals of very low abundance in the Earth's crust and, correspondingly, the biosphere is only adapted to very small concentrations of these elements. However, in modern semiconductor industries, both elements play a central role and are incorporated in devices of mass production such as smartphones and digital cameras. The resulting considerable increase in production, use and discharge of indium and gallium throughout the last two decades, with a continuous and fast increase in the near future, raises questions regarding the fate of both elements in the environment. However, the transport behavior of these two metals in soils and groundwater systems remains poorly understood to date. Because of the low solubility of both elements in aqueous solutions, trisodium citrate was used as a complexation agent to stabilize the solutions, enabling investigation of the transport of these metals at neutral pH. Column experiments showed different binding capacities for indium and gallium, where gallium is much more mobile compared to indium and both metals are substantially retarded in the column. Different affinities were also confirmed by examining sorption isotherms of indium and gallium in equilibrium batch systems. The effect of natural organic matter on the mobility of indium and gallium was also studied, by addition of humic acid. For both metals, the presence of humic acid affects the sorption dynamics: for indium, sorption is strongly inhibited leading to much higher mobility, whereas gallium showed a slightly higher sorption affinity and very similar mobility compared to the same setup without humic acid addition. However, in all cases, the binding capacity of gallium to quartz is much weaker than that of indium. These results are consistent with the assumption that indium and gallium form different types

  11. Thermodynamic parameters of U (VI) sorption onto soils in aquatic systems.

    Science.gov (United States)

    Kumar, Ajay; Rout, Sabyasachi; Ghosh, Malay; Singhal, Rakesh Kumar; Ravi, Pazhayath Mana

    2013-01-01

    The thermodynamic parameters viz. the standard free energy (∆Gº), Standard enthalpy change (∆Hº) and standard entropy change (∆Sº) were determined using the obtained values of distribution coefficient (kd) of U (VI) in two different types of soils (agricultural and undisturbed) by conducting a batch equilibrium experiment with aqueous media (groundwater and deionised water) at two different temperatures 25°C and 50°C. The obtained distribution coefficients (kd) values of U for undisturbed soil in groundwater showed about 75% higher than in agricultural soil at 25°C while in deionised water, these values were highly insignificant for both soils indicating that groundwater was observed to be more favorable for high surface sorption. At 50°C, the increased kd values in both soils revealed that solubility of U decreased with increasing temperature. Batch adsorption results indicated that U sorption onto soils was promoted at higher temperature and an endothermic and spontaneous interfacial process. The high positive values of ∆Sº for agricultural soil suggested a decrease in sorption capacity of U in that soil due to increased randomness at solid-solution interface. The low sorption onto agricultural soil may be due to presence of high amount of coarse particles in the form of sand (56%). Geochemical modeling predicted that mixed hydroxo-carbonato complexes of uranium were the most stable and abundant complexes in equilibrium solution during experimental.

  12. Sorption of samarium in iron (II) and (III) phosphates in aqueous systems

    International Nuclear Information System (INIS)

    Diaz F, J.C.

    2006-01-01

    The radioactive residues that are stored in the radioactive confinements its need to stay isolated of the environment while the radioactivity levels be noxious. An important mechanism by which the radioactive residues can to reach the environment, it is the migration of these through the underground water. That it makes necessary the investigation of reactive materials that interacting with those radionuclides and that its are able to remove them from the watery resources. The synthesis and characterization of materials that can be useful in Environmental Chemistry are very important because its characteristics are exposed and its behavior in chemical phenomena as the sorption watery medium is necessary to use it in the environmental protection. In this work it was carried out the sorption study of the samarium III ion in the iron (II) and (III) phosphate; obtaining the sorption isotherms in function of pH, of the phosphate mass and of the concentration of the samarium ion using UV-visible spectroscopy to determine the removal percentage. The developed experiments show that as much the ferrous phosphate as the ferric phosphate present a great affinity by the samarium III, for what it use like reactive material in contention walls can be very viable because it sorption capacity has overcome 90% to pH values similar to those of the underground and also mentioning that the form to obtain these materials is very economic and simple. (Author)

  13. Effects of solvent evaporation on water sorption/solubility and nanoleakage of adhesive systems

    Directory of Open Access Journals (Sweden)

    Talita Baumgratz Cachapuz CHIMELI

    2014-07-01

    Full Text Available Objective: To evaluate the influence of solvent evaporation in the kinetics of water diffusion (water sorption-WS, solubility-SL, and net water uptake and nanoleakage of adhesive systems. Material and Methods: Disk-shaped specimens (5.0 mm in diameter x 0.8 mm in thickness were produced (N=48 using the adhesives: Clearfil S3 Bond (CS3/Kuraray, Clearfil SE Bond - control group (CSE/Kuraray, Optibond Solo Plus (OS/Kerr and Scotchbond Universal Adhesive (SBU/3M ESPE. The solvents were either evaporated for 30 s or not evaporated (N=24/per group, and then photoactivated for 80 s (550 mW/cm2. After desiccation, the specimens were weighed and stored in distilled water (N=12 or mineral oil (N=12 to evaluate the water diffusion over a 7-day period. Net water uptake (% was also calculated as the sum of WS and SL. Data were submitted to 3-way ANOVA/Tukey's test (α=5%. The nanoleakage expression in three additional specimens per group was also evaluated after ammoniacal silver impregnation after 7 days of water storage under SEM. Results: Statistical analysis revealed that only the factor "adhesive" was significant (p<0.05. Solvent evaporation had no influence in the WS and SL of the adhesives. CSE (control presented significantly lower net uptake (5.4%. The nanoleakage was enhanced by the presence of solvent in the adhesives. Conclusions: Although the evaporation has no effect in the kinetics of water diffusion, the nanoleakage expression of the adhesives tested increases when the solvents are not evaporated.

  14. Study on a high capacity two-stage free piston Stirling cryocooler working around 30 K

    Science.gov (United States)

    Wang, Xiaotao; Zhu, Jian; Chen, Shuai; Dai, Wei; Li, Ke; Pang, Xiaomin; Yu, Guoyao; Luo, Ercang

    2016-12-01

    This paper presents a two-stage high-capacity free-piston Stirling cryocooler driven by a linear compressor to meet the requirement of the high temperature superconductor (HTS) motor applications. The cryocooler system comprises a single piston linear compressor, a two-stage free piston Stirling cryocooler and a passive oscillator. A single stepped displacer configuration was adopted. A numerical model based on the thermoacoustic theory was used to optimize the system operating and structure parameters. Distributions of pressure wave, phase differences between the pressure wave and the volume flow rate and different energy flows are presented for a better understanding of the system. Some characterizing experimental results are presented. Thus far, the cryocooler has reached a lowest cold-head temperature of 27.6 K and achieved a cooling power of 78 W at 40 K with an input electric power of 3.2 kW, which indicates a relative Carnot efficiency of 14.8%. When the cold-head temperature increased to 77 K, the cooling power reached 284 W with a relative Carnot efficiency of 25.9%. The influences of different parameters such as mean pressure, input electric power and cold-head temperature are also investigated.

  15. Investigation of pressure drop in capillary tube for mixed refrigerant Joule-Thomson cryocooler

    International Nuclear Information System (INIS)

    Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

    2014-01-01

    A capillary tube is commonly used in small capacity refrigeration and air-conditioning systems. It is also a preferred expansion device in mixed refrigerant Joule-Thomson (MR J-T) cryocoolers, since it is inexpensive and simple in configuration. However, the flow inside a capillary tube is complex, since flashing process that occurs in case of refrigeration and air-conditioning systems is metastable. A mixture of refrigerants such as nitrogen, methane, ethane, propane and iso-butane expands below its inversion temperature in the capillary tube of MR J-T cryocooler and reaches cryogenic temperature. The mass flow rate of refrigerant mixture circulating through capillary tube depends on the pressure difference across it. There are many empirical correlations which predict pressure drop across the capillary tube. However, they have not been tested for refrigerant mixtures and for operating conditions of the cryocooler. The present paper assesses the existing empirical correlations for predicting overall pressure drop across the capillary tube for the MR J-T cryocooler. The empirical correlations refer to homogeneous as well as separated flow models. Experiments are carried out to measure the overall pressure drop across the capillary tube for the cooler. Three different compositions of refrigerant mixture are used to study the pressure drop variations. The predicted overall pressure drop across the capillary tube is compared with the experimentally obtained value. The predictions obtained using homogeneous model show better match with the experimental results compared to separated flow models

  16. Temperature oscillation suppression of GM cryocooler

    Science.gov (United States)

    Okidono, K.; Oota, T.; Kurihara, H.; Sumida, T.; Nishioka, T.; Kato, H.; Matsumura, M.; Sasaki, O.

    2012-12-01

    GM cryocooler is a convenient refrigerator to achieve low temperatures about 4 K, while it is not suitable for precise measurements because of the large temperature oscillation of typically about 0.3 K. To resolve this problem, we have developed an adapter (He-pot) with a simple structure as possible. From the thermodynamic consideration, both heat capacity and thermal conductance should be large in order to reduce the temperature oscillation without compromising cooling power. Optimal structure of the He-pot is a copper cylinder filled with high pressure He-gas at room temperature. This can reduce the temperature oscillation to less than 10 mK below a certain temperature TH without compromising cooling power. TH are 3.8 and 4.5 for filled He-gas pressures of 90 and 60 atm, respectively. By using this He-pot, GM cryocooler can be applied to such as precise physical property measurements and THz detection.

  17. Miniature PT Cryocooler Activated by Resonant Piezoelectric Compressor and Passive Warm Expander

    Science.gov (United States)

    Sobol, S.; Grossman, G.

    2017-12-01

    A novel type of PZT-based compressor operating at mechanical resonance, suitable for pneumatically-driven Stirling-type cryocoolers, was presented at CEC-ICMC 2015. The detailed concept, analytical model and the test results on the preliminary prototype were reported earlier and presented at ICC17. Despite some mismatch between the impedances and insufficient structural stiffness, this compressor demonstrated the feasibility to drive our miniature Pulse Tube cryocooler MTSa, operating at 103 Hz and requiring an average PV power of 11 W, filling pressure of 40 Bar and a pressure ratio of 1.3. At ICC19 the prototype of a miniature passive warm expander (WE) was presented. The WE mechanism included a phase shifting piston suspended on a silicone diaphragm, a mass element, and a viscous damping system. Several technical drawbacks prevented perfect matching between the WE and MTSa; however, the presented prototype proved the ability to create any flow-to-pressure phase appropriate for a PT cryocooler. This paper concentrates on integration of the MTSa cryocooler with the recently modified PZT compressor operating at corrected mechanical resonance and the modified WE, which was also updated recently to match the MTSa requirements.

  18. Modified-Collins cryocooler for zero-boiloff storage of cryogenic fuels in space

    Science.gov (United States)

    Hannon, Charles L.; Krass, Brady; Hogan, Jake; Brisson, John

    2012-06-01

    Future lunar and planetary explorations will require the storage of cryogenic propellants, particularly liquid oxygen (LOX) and liquid hydrogen (LH2), in low earth orbit (LEO) for periods of time ranging from days to months, and possibly longer. Without careful thermal management, significant quantities of stored liquid cryogens can be lost due to boil-off. Boil-off can be minimized by a variety of passive means including insulation, sun shades and passive radiational cooling. However, it has been shown that active cooling using space cryocoolers has the potential to result in Zero Boil-Off (ZBO) and the launch-mass savings using active cooling exceeds that of passive cooling of LOX for mission durations in LEO of less than 1 week, and for LH2 after about 2 months in LEO. Large-scale DC-flow cryogenic refrigeration systems operate at a fraction of the specific power levels required by small-scale AC-flow cryocoolers. The efficiency advantage of DC-flow cryogenic cycles motivates the current development of a cryocooler based on a modification of the Collins Cycle. The modified Collins cycle design employs piston type expanders that support high operating pressure ratios, electromagnetic valves that enable "floating pistons", and recuperative heat transfer. This paper will describe the design of a prototype Modified-Collins cryocooler for ZBO storage of cryogenic fuels in space.

  19. Modeling coupled sorption and transformation of 17β-estradiol–17-sulfate in soil–water systems

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Xuelian; Shrestha, Suman L.; Casey, Francis X. M.; Hakk, Heldur; Fan, Zhaosheng

    2014-11-01

    Animal manure is the primary source of exogenous free estrogens in the environment, which are known endocrine-disrupting chemicals to disorder the reproduction system of organisms. Conjugated estrogens can act as precursors to free estrogens, which may increase the total estrogenicity in the environment. In this study, a comprehensive model was used to simultaneously simulate the coupled sorption and transformation of a sulfate estrogen conjugate, 17 beta-estradiol-17-sulfate (E2-17S), in various soil-water systems (non-sterile/sterile; topsoil/subsoil). The simulated processes included multiple transformation pathways (i.e. hydroxylation, hydrolysis, and oxidation) and mass transfer between the aqueous, reversibly sorbed, and irreversibly sorbed phases of all soils for E2-17S and its metabolites. The conceptual model was conceived based on a series of linear sorption and first-order transformation expressions. The model was inversely solved Using finite difference to estimate process parameters. A global optimization method was applied for the inverse analysis along with variable model restrictions to estimate 36 parameters. The model provided a satisfactory simultaneous fit (R-adj(2) = 0.93 and d = 0.87) of all the experimental data and reliable parameter estimates. This modeling study improved the understanding on fate and transport of estrogen conjugates under various soil-water conditions.

  20. THE EFFECTS OF HALIDE MODIFIERS ON THE SORPTION KINETICS OF THE LI-MG-N-H SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Anton, D.; Gray, J.; Price, C.; Lascola, R.

    2011-07-20

    The effects of different transition metal halides (TiCl{sub 3}, VCl{sub 3}, ScCl{sub 3} and NiCl{sub 2}) on the sorption properties of the 1:1 molar ratio of LiNH{sub 2} to MgH{sub 2} are investigated. The modified mixtures were found to contain LiNH{sub 2}, MgH{sub 2} and LiCl. TGA results showed that the hydrogen desorption temperature was reduced with the modifier addition in this order: TiCl{sub 3} > ScCl{sub 3} > VCl{sub 3} > NiCL{sub 2}. Ammonia release was not significantly reduced resulting in a weight loss greater than the theoretical hydrogen storage capacity of the material. The isothermal sorption kinetics of the modified systems showed little improvement after the first dehydrogenation cycle over the unmodified system but showed drastic improvement in rehydrogenation cycles. X-ray diffraction and Raman spectroscopy identified the cycled material to be composed of LiH, MgH{sub 2}, Mg(NH{sub 2}){sub 2} and Mg{sub 3}N{sub 2}.

  1. THE AFFECTS OF HALIDE MODIFIERS ON THE SORPTION KINETICS OF THE LI-MG-N-H SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Erdy, C.; Gray, J.; Lascola, R.; Anton, D.

    2010-12-16

    In this present work, the affects of different transition metal halides (TiCl{sub 3}, VCl{sub 3}, ScCl{sub 3} and NiCl{sub 2}) on the sorption properties of the 1:1 molar ratio of LiNH{sub 2} to MgH{sub 2} are investigated. The modified mixtures were found to contain LiNH{sub 2}, MgH{sub 2} and LiCl. TGA results showed that the hydrogen desorption temperature was reduced with the modifier addition in this order: TiCl{sub 3}>ScCl{sub 3}>VCl{sub 3}>NiCl{sub 2}. Ammonia release was not significantly reduced resulting in a weight loss greater than the theoretical hydrogen storage capacity of the material. The isothermal sorption kinetics of the modified systems showed little improvement after the first dehydrogenation cycle over the unmodified system but showed drastic improvement in rehydrogenation cycles. XRD and Raman spectroscopy identified the cycled material to be composed of LiH, MgH{sub 2}, Mg(NH{sub 2}){sub 2} and Mg{sub 3}N{sub 2}.

  2. Simulation of thermal processes in superconducting pancake coils cooled by GM cryocooler

    International Nuclear Information System (INIS)

    Lebioda, M; Rymaszewski, J; Korzeniewska, E

    2014-01-01

    This article presents the thermal model of a small scale superconducting magnetic energy storage system with the closed cycle helium cryocooler. The authors propose the use of contact-cooled coils with maintaining the possibility of the system reconfiguring. The model assumes the use of the second generation superconducting tapes to make the windings in the form of flat discs (pancakes). The paper presents results for a field model of the single pancake coil and the winding system consisting of several coils.

  3. Development of miniature moving magnet cryocooler SX040

    Science.gov (United States)

    Rühlich, I.; Mai, M.; Rosenhagen, C.; Schreiter, A.; Möhl, C.

    2011-06-01

    State of the art high performance cooled IR systems need to have more than just excellent E/O performance. Minimum size weight and power (SWaP) are the design goals to meet our forces' mission requirements. Key enabler for minimum SWaP of IR imagers is the operation temperature of the focal plane array (FPA) employed. State of the art MCT or InAsSb nBn technology has the potential to rise the FPA temperature from 77 K to 130-150 K (high operation temperature HOT) depending on the specific cut-off wavelength. Using a HOT FPA will significantly lower SWaP and keep those parameters finally dominated by the employed cryocooler. Therefore compact high performance cryocoolers are mandatory. For highest MTTF life AIM developed its Flexure Bearing Moving Magnet product family "SF". Such coolers achieve more than 20000 h MTTF with Stirling type expander and more than 5 years MTTF life with Pulse Tube coldfinger (like for Space applications). To keep the high lifetime potential but to significantly improve SWaP AIM is developing its "SX" type cooler family. The new SX040 cooler incorporates a highly efficient dual piston Moving Magnet driving mechanism resulting in very compact compressor of less than 100mm length. The cooler's high lifetime is also achieved by placing the coils outside the helium vessel as usual for moving magnet motors. The mating ¼" expander is extremely compact with less than 63 mm length. This allows a total dewar length from optical window to expander warm end of less than 100 mm even for large cold shields. The cooler is optimized for HOT detectors with operating temperatures exceeding 95 K. While this kind of cooler is the perfect match for many applications, handheld sights or targeting devices for the dismounted soldier are even more challenging with respect to SWaP. AIM therefore started to develop an even smaller cooler type with single piston and balancer. This paper gives an overview on the development of this new compact cryocooler. Technical

  4. AIM cryocooler developments for HOT detectors

    Science.gov (United States)

    Rühlich, I.; Mai, M.; Withopf, A.; Rosenhagen, C.

    2014-06-01

    Significantly increased FPA temperatures for both Mid Wave and Long Wave IR detectors, i.e. HOT detectors, which have been developed in recent years are now leaving the development phase and are entering real application. HOT detectors allowing to push size weight and power (SWaP) of Integrated Detectors Cooler Assemblies (IDCA's) to a new level. Key component mainly driving achievable weight, volume and power consumption is the cryocooler. AIM cryocooler developments are focused on compact, lightweight linear cryocoolers driven by compact and high efficient digital cooler drive electronics (DCE) to also achieve highest MTTF targets. This technology is using moving magnet driving mechanisms and dual or single piston compressors. Whereas SX030 which was presented at SPIE in 2012 consuming less 3 WDC to operate a typical IDCA at 140K, next smaller cooler SX020 is designed to provide sufficient cooling power at detector temperature above 160K. The cooler weight of less than 200g and a total compressor length of 60mm makes it an ideal solution for all applications with limited weight and power budget, like in handheld applications. For operating a typical 640x512, 15μm MW IR detector the power consumption will be less than 1.5WDC. MTTF for the cooler will be in excess of 30,000h and thus achieving low maintenance cost also in 24/7 applications. The SX020 compressor is based on a single piston design with integrated passive balancer in a new design achieves very low exported vibration in the order of 100mN in the compressor axis. AIM is using a modular approach, allowing the chose between 5 different compressor types for one common Stirling expander. The 6mm expander with a total length of 74mm is now available in a new design that fits into standard dewar bores originally designed for rotary coolers. Also available is a 9mm coldfinger in both versions. In development is an ultra-short expander with around 35mm total length to achieve highest compactness. Technical

  5. Ball-milling and AlB2 addition effects on the hydrogen sorption properties of the CaH2 + MgB2 system

    International Nuclear Information System (INIS)

    Schiavo, B.; Girella, A.; Agresti, F.; Capurso, G.; Milanese, C.

    2011-01-01

    Research highlights: → Calcium hydride + magnesium-aluminum borides as candidates for hydrogen storage. → Long time ball milling improves hydrogen sorption kinetics of the CaH 2 +MgB 2 system. → Coexistence of MgB 2 and AlB 2 does not improve hydrogen sorption performances. → Total substitution of MgB 2 with AlB 2 improves the system kinetics and reversibility. → Below 400 deg. C almost the full hydrogen capacity of the CaH 2 + AlB 2 system is reached. - Abstract: Among the borohydrides proposed for solid state hydrogen storage, Ca(BH 4 ) 2 is particularly interesting because of its favourable thermodynamics and relatively cheap price. Composite systems, where other species are present in addition to the borohydride, show some advantages in hydrogen sorption properties with respect to the borohydrides alone, despite a reduction of the theoretical storage capacity. We have investigated the milling time influence on the sorption properties of the CaH 2 + MgB 2 system from which Ca(BH 4 ) 2 and MgH 2 can be synthesized by hydrogen absorption process. Manometric and calorimetric measurements showed better kinetics for long time milled samples. We found that the total substitution of MgB 2 with AlB 2 in the starting material can improve the sorption properties significantly, while the co-existence of both magnesium and aluminum borides in the starting mixture did not cause any improvement. Rietveld refinements of the X-ray powder diffraction spectra were used to confirm the hypothesized reactions.

  6. Performance analysis of an integrated energy storage and energy upgrade thermochemical solid–gas sorption system for seasonal storage of solar thermal energy

    International Nuclear Information System (INIS)

    Li, Tingxian; Wang, Ruzhu; Kiplagat, Jeremiah K.; Kang, YongTae

    2013-01-01

    An innovative dual-mode thermochemical sorption energy storage method is proposed for seasonal storage of solar thermal energy with little heat losses. During the charging phase in summer, solar thermal energy is stored in form of chemical bonds resulting from thermochemical decomposition process, which enables the stored energy to be kept several months at ambient temperature. During the discharging phase in winter, the stored thermal energy is released in the form of chemical reaction heat resulting from thermochemical synthesis process. Thermodynamic analysis showed that the advanced dual-mode thermochemical sorption energy storage is an effective method for the long-term seasonal storage of solar energy. A coefficient of performance (COP h ) of 0.6 and energy density higher than 1000 kJ/kg of salt can be attained from the proposed system. During the discharging phase at low ambient temperatures, the stored thermal energy can be upgraded by use of a solid–gas thermochemical sorption heat transformer cycle. The proposed thermochemical sorption energy storage has distinct advantages over the conventional sensible heat and latent heat storage, such as higher energy storage density, little heat losses, integrated energy storage and energy upgrade, and thus it can contribute to improve the seasonal utilization of solar thermal energy. - Highlights: ► A dual-mode solid thermochemical sorption is proposed for seasonal solar thermal energy storage. ► Energy upgrade techniques into the energy storage system are integrated. ► Performance of the proposed seasonal energy storage system is evaluated. ► Energy density and COP h from the proposed system are as high as 1043 kJ/kg of salt and 0.60, respectively

  7. Study of low vibration 4 K pulse tube cryocoolers

    Science.gov (United States)

    Xu, Mingyao; Nakano, Kyosuke; Saito, Motokazu; Takayama, Hirokazu; Tsuchiya, Akihiro; Maruyama, Hiroki

    2012-06-01

    Sumitomo Heavy Industries, Ltd. (SHI) has been continuously improving the efficiency and reducing the vibration of a 4 K pulse tube cryocooler. One advantage of a pulse tube cryocooler over a GM cryocooler is low vibration. In order to reduce vibration, both the displacement and the acceleration have to be reduced. The vibration acceleration can be reduced by splitting the valve unit from the cold head. One simple way to reduce vibration displacement is to increase the wall thickness of the tubes on the cylinder. However, heat conduction loss increases while the wall thickness increases. To overcome this dilemma, a novel concept, a tube with non-uniform wall thickness, is proposed. Theoretical analysis of this concept, and the measured vibration results of an SHI lowvibration pulse tube cryocooler, will be introduced in this paper.

  8. Cryocooler With Cold Compressor for Deep Space Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The unique built-in design features of the proposed mini pulse tube cryocooler avoid all thermal expansion issues enabling it to operate within a cold, 150 K...

  9. Low-T, Low-Q Cryocoolers for Science Instruments

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of the planned research is to advance the current space science instruments through the development of light weight and low power cryocoolers. Currently,...

  10. Performance Characterization of the Astrium 10k Developmental Cryocooler

    National Research Council Canada - National Science Library

    Bruninghaus, C. H; Kallman, J. P; Tomlinson, B. J., Jr; Myrick, E

    2002-01-01

    .... Under the technology development program, Astrium (formerly Matra Marconi Space) in Stevenage, United Kingdom, developed a Stirling cycle cryocooler with four Oxford flexure compressors and a two-stage expansion cold end...

  11. Sorption mechanism of U(VI) on to natural soil system: a study using intra-particle diffusion model

    International Nuclear Information System (INIS)

    Rout, S.; Kumar, A.; Ravi, P.M.; Tripathi, R.M.

    2015-01-01

    The rate of U(VI) adsorption onto natural soils from different parent materials has been studied experimentally using the batch adsorption method at five different initial U(VI) concentrations. The utility of Weber and Morris Interparticle diffusion model for describing the mechanism and kinetics of sorption is discussed. The study reveals that the mechanism of U(VI) sorption involves three steps such as: external surface adsorption, gradual adsorption stage which is the rate determining step and the last portion refers to the final equilibrium stage. The steps involved in sorption of U(VI) on to soil is same irrespective of soil types and initial U(VI) concentration. (author)

  12. Miniature Joule-Thomson cryocooling principles and practice

    CERN Document Server

    Maytal, Ben-Zion

    2013-01-01

    This book is the first in English being entirely dedicated to Miniature Joule-Thomson Cryocooling. The category of Joule-Thomson (JT) cryocoolers takes us back to the roots of cryogenics, in 1895, with figures like Linde and Hampson. The "cold finger" of these cryocoolers is compact, lacks moving parts, and sustains a large heat flux extraction at a steady temperature. Potentially, they cool down unbeatably fast. For example, cooling to below 100 K (minus 173 Celsius) might be accomplished within only a few seconds by liquefying argon. A level of about 120 K can be reached almost instantly with krypton. Indeed, the species of coolant plays a central role dictating the size, the intensity and the level of cryocooling. It is the JT effect that drives these cryocoolers and reflects the deviation of the "real" gas from the ideal gas properties. The nine chapters of the book are arranged in five parts. • The Common Principle of Cyrocoolers shared across the broad variety of cryocooler types • Theoretical Aspec...

  13. Linear-drive cryocoolers for the Department of Defense standard advanced dewar assembly (SADA)

    Science.gov (United States)

    Tate, Garin S.

    2005-05-01

    The Standard Advanced Dewar Assembly (SADA) is the critical module in the Department of Defense (DoD) standardization of scanning second-generation thermal imaging systems. The DoD has established a family of SADAs to fulfill a range of performance requirements for various platforms. The SADA consists of the Infrared Focal Plane Array (IRFPA), Dewar, Command & Control Electronics (C&CE), and the cryogenic cooler, and is used in platforms such as the Apache helicopter, the M1A2 Abrams main battle tank, the M2 Bradley Infantry Fighting Vehicle, and the Javelin Command Launch Unit (CLU). In support of the family of SADAs, the DoD defined a complementary family of tactical linear drive cryocoolers. The Stirling cycle linear drive cryocoolers are utilized to cool the Infrared Focal Plane Arrays (IRFPAs) in the SADAs. These coolers are required to have low input power, a quick cool-down time, low vibration output, low audible noise, and a higher reliability than currently fielded rotary coolers. These coolers must also operate in a military environment with its inherent high vibration level and temperature extremes. This paper will (1) outline the characteristics of each cryocooler, (2) present the status and results of qualification tests, (3) present the status of production efforts, and (4) present the status of efforts to increase linear drive cooler reliability.

  14. Development of a miniature Stirling cryocooler for LWIR small satellite applications

    Science.gov (United States)

    Kirkconnell, C. S.; Hon, R. C.; Perella, M. D.; Crittenden, T. M.; Ghiaasiaan, S. M.

    2017-05-01

    The optimum small satellite (SmallSat) cryocooler system must be extremely compact and lightweight, achieved in this paper by operating a linear cryocooler at a frequency of approximately 300 Hz. Operation at this frequency, which is well in excess of the 100-150 Hz reported in recent papers on related efforts, requires an evolution beyond the traditional Oxford-class, flexure-based methods of setting the mechanical resonance. A novel approach that optimizes the electromagnetic design and the mechanical design together to simultaneously achieve the required dynamic and thermodynamic performances is described. Since highly miniaturized pulse tube coolers are fundamentally ill-suited for the sub-80K temperature range of interest because the boundary layer losses inside the pulse tube become dominant at the associated very small pulse tube size, a moving displacer Stirling cryocooler architecture is used. Compact compressor mechanisms developed on a previous program are reused for this design, and they have been adapted to yield an extremely compact Stirling warm end motor mechanism. Supporting thermodynamic and electromagnetic analysis results are reported.

  15. RMs1: qualification results of the rotary miniature Stirling cryocooler at Thales Cryogenics

    Science.gov (United States)

    Martin, Jean-Yves; Seguineau, Cédric; Van-Acker, Sébastien; Sacau, Mikel; Le Bordays, Julien; Etchanchu, Thierry; Vasse, Christophe; Abadie, Christian; Laplagne, Gilles; Benschop, Tonny

    2017-05-01

    The trend for miniaturized Integrated Dewar and Cooler Assemblies (IDCA) has been confirmed over the past few years with several mentions of a new generation of IR detector working at High Operating Temperature (HOT). This key technology enables the use of cryocooler with reduced needs of cryogenics power. As a consequence, miniaturized IDCA are the combination of a HOT IR detector coupled with a low-size, low-weight and low-power (SWaP) cryocooler. Thales Cryogenics has developed his own line of SWaP products. Qualification results on linear solution where shown last year. The current paper focuses on the latest results obtained on RMs1 prototypes, the new rotary SWaP cryocooler from Thales Cryogenics. Cryogenic performances and induced vibrations are presented. In a second part, progress is discussed on compactness and weight on one side, and on power consumption on the other side. It shows how the trade-off made between weight and power consumption could lead to an optimized solution at system level. At least, an update is made on the qualification status.

  16. Sorption studies of uranium in sediment-groundwater systems from the natural analogue sites of Needle's Eye and Broubster

    International Nuclear Information System (INIS)

    Higgo, J.J.; Falck, W.E.; Hooker, P.J.

    1990-01-01

    This report describes the results of sorption experiments designed to provide essential data for migration modelling. Sorption of 233 U from natural ground-water onto peat from Broubster and silt from Needle's Eye was studied under atmospheric conditions and different pH regimes. The temperature was maintained at 10 0 C and, in the case of Needle's Eye silt, the kinetics of sorption were followed. The results were analyzed in conjunction with speciation modelling in an attempt to understand the sorption mechanisms and to extrapolate the findings to cover the range of conditions likely to be met in the field. This work is part of the CEC project Mirage - Second phase, research area 'Natural analogues'

  17. Enhancement of gravimetric forced flow through system to determine sorption, swelling, and mass transfer characteristics of liquid sorbents

    Science.gov (United States)

    Dresp, G.; Petermann, M.; Fieback, T. M.

    2018-04-01

    An existing apparatus for forced flow through of liquid sorbents has been enhanced with an optically accessible system including a transparent crucible, high pressure viewing cell, and camera. With this optical system, the active surface area between gas and liquid can be determined in situ for the first time under industrial process conditions while maintaining the accuracy of a magnetic suspension balance. Additionally, occurring swelling and the resulting buoyancy changes can now be corrected, further improving the quality of the data. Validation measurements focusing on the sorption isotherms, swelling, and bubble geometry of 1-butyl-3-methylimidazolium tetrafluoroborate with nitrogen at 303 K and up to 17 MPa, as well as with carbon dioxide at 303 K, 323 K, and 373 K at up to 3.5 MPa were completed. Absorption of nitrogen resulted in no observable volume change, whereas absorption of carbon dioxide resulted in temperature independent swelling of up to 9.8%. The gas bubble's structure and behavior during its ascend through the liquid was optically tracked in situ. Combining these two data sets with the absorption kinetics forms the basis to determine the measuring system independent mass transfer coefficients, which are applicable in other laboratory scale and industrial processes.

  18. Combined effects of DOM extracted from site soil/compost and biosurfactant on the sorption and desorption of PAHs in a soil-water system

    Energy Technology Data Exchange (ETDEWEB)

    Yu Hui, E-mail: yuhui200@uregina.ca [Environmental Systems Engineering Program, Faculty of Engineering and Applied Science, University of Regina, Regina, SK S4S 0A2 (Canada); Huang Guohe, E-mail: gordon.huang@uregina.ca [Environmental Systems Engineering Program, Faculty of Engineering and Applied Science, University of Regina, Regina, SK S4S 0A2 (Canada); An Chunjiang, E-mail: an209@uregina.ca [Environmental Systems Engineering Program, Faculty of Engineering and Applied Science, University of Regina, Regina, SK S4S 0A2 (Canada); Wei Jia, E-mail: jia.wei@iseis.org [Environmental Systems Engineering Program, Faculty of Engineering and Applied Science, University of Regina, Regina, SK S4S 0A2 (Canada)

    2011-06-15

    Highlights: {yields} The combined DOM and biosurfactant significantly enhanced desorption of PAHs. {yields} Compost DOM exhibited higher desorption enhancement capacity than the soil DOM. {yields} Competition among PAHs, DOM and biosurfactant for sorption site determined desorption of PAHs from soil. {yields} Formation of DOM-biosurfactant complex enhance desorption extent of PAHs. - Abstract: The combined effects of DOM and biosurfactant on the sorption/desorption behavior of phenanthrene (PHE) and pyrene (PYR) in soil water systems were systematically investigated. Two origins of DOMs (extracted from soil and extracted from food waste compost) and an anionic biosurfactant (rhamnolipid) were introduced. The presence of DOM in the aqueous phase could decrease the sorption of PAHs, thus influence their mobility. Desorption enhancement for both PHE and PYR in the system with compost DOM was greater than that in the soil DOM system. This is due to the differences in specific molecular structures and functional groups of two DOMs. With the co-existence of biosurfactant and DOM, partitioning is the predominant process and the desorption extent was much higher than the system with DOM or biosurfactant individually. For PHE, the desorption enhancement of combined DOM and biosurfactant was larger than the sum of DOM or biosurfactant; however desorption enhancement for PYR in the combined system was less than the additive enhancement in two individual system under low PAH concentration. This could be explained as the competition sorption among PAHs, DOM and biosurfactant. The results of this study will help to clarify the transport of petroleum pollutants in the remediation of HOCs-contaminated soils.

  19. Combined effects of DOM extracted from site soil/compost and biosurfactant on the sorption and desorption of PAHs in a soil-water system

    International Nuclear Information System (INIS)

    Yu Hui; Huang Guohe; An Chunjiang; Wei Jia

    2011-01-01

    Highlights: → The combined DOM and biosurfactant significantly enhanced desorption of PAHs. → Compost DOM exhibited higher desorption enhancement capacity than the soil DOM. → Competition among PAHs, DOM and biosurfactant for sorption site determined desorption of PAHs from soil. → Formation of DOM-biosurfactant complex enhance desorption extent of PAHs. - Abstract: The combined effects of DOM and biosurfactant on the sorption/desorption behavior of phenanthrene (PHE) and pyrene (PYR) in soil water systems were systematically investigated. Two origins of DOMs (extracted from soil and extracted from food waste compost) and an anionic biosurfactant (rhamnolipid) were introduced. The presence of DOM in the aqueous phase could decrease the sorption of PAHs, thus influence their mobility. Desorption enhancement for both PHE and PYR in the system with compost DOM was greater than that in the soil DOM system. This is due to the differences in specific molecular structures and functional groups of two DOMs. With the co-existence of biosurfactant and DOM, partitioning is the predominant process and the desorption extent was much higher than the system with DOM or biosurfactant individually. For PHE, the desorption enhancement of combined DOM and biosurfactant was larger than the sum of DOM or biosurfactant; however desorption enhancement for PYR in the combined system was less than the additive enhancement in two individual system under low PAH concentration. This could be explained as the competition sorption among PAHs, DOM and biosurfactant. The results of this study will help to clarify the transport of petroleum pollutants in the remediation of HOCs-contaminated soils.

  20. Raytheon's next generation compact inline cryocooler architecture

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, B. R.; Bellis, L.; Ellis, M. J.; Conrad, T. [Raytheon Space and Airborne Systems, 2000 E. El Segundo Blvd., El Segundo, CA 90245 (United States)

    2014-01-29

    Since the 1970s, Raytheon has developed, built, tested and integrated high performance cryocoolers. Our versatile designs for single and multi-stage cryocoolers provide reliable operation for temperatures from 10 to 200 Kelvin with power levels ranging from 50 W to nearly 600 W. These advanced cryocoolers incorporate clearance seals, flexure suspensions, hermetic housings and dynamic balancing to provide long service life and reliable operation in all relevant environments. Today, sensors face a multitude of cryocooler integration challenges such as exported disturbance, efficiency, scalability, maturity, and cost. As a result, cryocooler selection is application dependent, oftentimes requiring extensive trade studies to determine the most suitable architecture. To optimally meet the needs of next generation passive IR sensors, the Compact Inline Raytheon Stirling 1-Stage (CI-RS1), Compact Inline Raytheon Single Stage Pulse Tube (CI-RP1) and Compact Inline Raytheon Hybrid Stirling/Pulse Tube 2-Stage (CI-RSP2) cryocoolers are being developed to satisfy this suite of requirements. This lightweight, compact, efficient, low vibration cryocooler combines proven 1-stage (RS1 or RP1) and 2-stage (RSP2) cold-head architectures with an inventive set of warm-end mechanisms into a single cooler module, allowing the moving mechanisms for the compressor and the Stirling displacer to be consolidated onto a common axis and in a common working volume. The CI cryocooler is a significant departure from the current Stirling cryocoolers in which the compressor mechanisms are remote from the Stirling displacer mechanism. Placing all of the mechanisms in a single volume and on a single axis provides benefits in terms of package size (30% reduction), mass (30% reduction), thermodynamic efficiency (>20% improvement) and exported vibration performance (≤25 mN peak in all three orthogonal axes at frequencies from 1 to 500 Hz). The main benefit of axial symmetry is that proven balancing

  1. Sorption separation of Eu and As from single-component systems by Fe-modified biochar. Kinetic and equilibrium study

    International Nuclear Information System (INIS)

    Fristak, Vladimir; Soja, Gerhard; Michalekova-Richveisova, Barbora; Pipiska, Martin; Viglasova, Eva; Galambos, Michal; Duriska, Libor; Moreno-Jimenez, Eduardo

    2017-01-01

    The utilization of carbonaceous materials in separation processes of radionuclides, heavy metals and metalloids represents a burning issue in environmental and waste management. The main objective of this study was to characterize the effect of chemical modification of corncob-derived biochar by Fe-impregnations on sorption efficiency of Eu and As as a model compounds of cationic lanthanides and anionic metalloids. The biochar sample produced in slow pyrolysis process at 500 C before (BC) and after (IBC) impregnation process was characterized by elemental, FTIR, SEM-EDX analysis to confirm the effectiveness of Fe-impregnation process. The basic physico-chemical properties showed differences in surface area and pH values of BC- and IBC-derived sorbents. Sorption processes of Eu and As by BC and IBC were characterized as a time- and initial concentration of sorbate-dependent processes. The sorption equilibrium was reached for both sorbates in 24 h of contact time. Batch equilibrium experiments revealed the increased maximum sorption capacities (Q max ) of IBC for As about more than 20 times (Q max BC 0.11 and Q max IBC 2.26 mg g -1 ). Our study confirmed negligible effect of Fe-impregnation on sorption capacity of biochar for Eu (Q max BC 0.89 and Q max IBC 0.98 mg g -1 ). The iron-impregnation of biochar-derived sorbents can be utilized as a valuable treatment method to produce stable and more effective sorption materials for various xenobiotics separation from liquid wastes and aqueous solutions.

  2. Sorption separation of Eu and As from single-component systems by Fe-modified biochar. Kinetic and equilibrium study

    Energy Technology Data Exchange (ETDEWEB)

    Fristak, Vladimir; Soja, Gerhard [Austrian Institute of Technology GmbH, Tulln (Austria). Energy Dept. Environmental Resources and Technologies; Michalekova-Richveisova, Barbora; Pipiska, Martin [Trnava Univ. (Slovakia). Dept. of Chemistry; Viglasova, Eva; Galambos, Michal [Comenius Univ., Bratislava (Slovakia). Dept. of Inorganic Chemistry; Duriska, Libor [Slovak Univ. of Technology in Bratislava, Trnava (Slovakia). Faculty of Materials Science and Technology; Moreno-Jimenez, Eduardo [Univ. Autonoma de Madrid (Spain). Dept. de Quimica Agricola y Bromatologia

    2017-03-15

    The utilization of carbonaceous materials in separation processes of radionuclides, heavy metals and metalloids represents a burning issue in environmental and waste management. The main objective of this study was to characterize the effect of chemical modification of corncob-derived biochar by Fe-impregnations on sorption efficiency of Eu and As as a model compounds of cationic lanthanides and anionic metalloids. The biochar sample produced in slow pyrolysis process at 500 C before (BC) and after (IBC) impregnation process was characterized by elemental, FTIR, SEM-EDX analysis to confirm the effectiveness of Fe-impregnation process. The basic physico-chemical properties showed differences in surface area and pH values of BC- and IBC-derived sorbents. Sorption processes of Eu and As by BC and IBC were characterized as a time- and initial concentration of sorbate-dependent processes. The sorption equilibrium was reached for both sorbates in 24 h of contact time. Batch equilibrium experiments revealed the increased maximum sorption capacities (Q{sub max}) of IBC for As about more than 20 times (Q{sub max} BC 0.11 and Q{sub max} IBC 2.26 mg g{sup -1}). Our study confirmed negligible effect of Fe-impregnation on sorption capacity of biochar for Eu (Q{sub max} BC 0.89 and Q{sub max} IBC 0.98 mg g{sup -1}). The iron-impregnation of biochar-derived sorbents can be utilized as a valuable treatment method to produce stable and more effective sorption materials for various xenobiotics separation from liquid wastes and aqueous solutions.

  3. Dynamic sorption data of selected radionuclides in sediment-water-systems from the Gorleben region

    International Nuclear Information System (INIS)

    Klotz, D.

    1993-01-01

    In 48 sediment-water-systems from the Gorleben region about 300 continuous-flow-column experiments were performed with 10 radionuclides. To simulate conditions as close as possible to natural ones (as regards the bedding of sediments, speed of filtration, environment, and microbiology - if necessary) for the sediment-groundwater-systems, the ranges of retardation factors for fresh, mixed and salt water systems were specified. For the investigated sand-water-systems, a comparison of the results obtained from continuous-flow-column and batch experiments for 85Sr and 134Cs was made. (orig.) [de

  4. Batch system for study of Cr(VI) Bio sorption by dried waste activated sludge

    International Nuclear Information System (INIS)

    Farzadkia, M.; Gholami, M.; Darvishi Cheshmeh Soltani, R.; Yaghmaeian, K.; Shams Khorramabadi, G.

    2009-01-01

    Activated sludge from wastewater treatment systems contains both bacteria and protozoa. The cell wall of bacteria essentially consists of various compounds, such as carboxyl, acidic polysaccharides,lipids, amino acids and other components. (Author)

  5. A nonproprietary, nonsecret program for calculating Stirling cryocoolers

    Science.gov (United States)

    Martini, W. R.

    1985-01-01

    A design program for an integrated Stirling cycle cryocooler was written on an IBM-PC computer. The program is easy to use and shows the trends and itemizes the losses. The calculated results were compared with some measured performance values. The program predicts somewhat optimistic performance and needs to be calibrated more with experimental measurements. Adding a multiplier to the friction factor can bring the calculated rsults in line with the limited test results so far available. The program is offered as a good framework on which to build a truly useful design program for all types of cryocoolers.

  6. Influence of sorption competition on sorption data for MX-80 bentonite used in performance assessment

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.; Marques Fernandes, M.

    2012-01-01

    Document available in extended abstract form only. In order to obtain a (quasi) mechanistic understanding of radionuclide uptake on clay minerals and argillaceous rocks, the majority of sorption experiments have been carried out on purified clay minerals such as montmorillonite and illite at trace concentrations (sorption edges), or as a function of concentration (sorption isotherms), with a single radionuclide under well-defined conditions in simple background electrolytes. As a result of such studies the 2 site proto-lysis non electrostatic surface complexation cation exchange (2SPNE SC/CE) sorption model, was developed and has been successfully applied to quantitatively describe the uptake of numerous radionuclides of differing valences as a function of pH and concentration on montmorillonite. In a deep geological repository for high level waste, stable impurities arise from many sources: they are present in the pore waters, in the tunnel back fill materials and host rock formations, they arise from the corrosion of the carbon steel canister and finally they are dissolved from the spent fuel and vitrified high level waste simultaneously with the radionuclides. These impurities, which are an integral part of a realistic repository system, can potentially compete with radionuclides for the sorption sites on the backfill materials and host rock and thus reduce their uptake on them. The influence of competitive sorption is not intrinsically included (or only partly so) in the sorption model. It is clearly an inherently important issue to quantify the influence of sorption competition on the transport of released radionuclides through the multi-barrier system in a deep repository. In this study an extreme case of a competitive sorption scenario in the near field of a HLW repository is presented. Two factors are considered: one associated with the high concentrations and the other with competitive sorption effects. The tendency in both cases is to cause a reduction in

  7. Characterizing pesticide sorption and degradation in macro scale biopurification systems using column displacement experiments

    International Nuclear Information System (INIS)

    Wilde, Tineke de; Spanoghe, Pieter; Mertens, Jan; Sniegowksi, Kristel; Ryckeboer, Jaak; Jaeken, Peter; Springael, Dirk

    2009-01-01

    The efficiency of biopurification systems to treat pesticide-contaminated water was previously studied in microcosms. To validate the obtained results, macrocosm systems were set-up. Four pesticides (linuron, isoproturon, bentazone, and metalaxyl) were continuously applied to ten different organic substrate mixes. Retention of the pesticides was similar and in some cases slightly lower in the macrocosms compared to the microcosms. Differences in retention between the different mixes were however minimal. Moreover, the classification of the retention strength of the pesticides was identical to that observed in microcosms: linuron > isoproturon > metalaxyl > bentazone. Monod kinetics were used to describe delayed degradation, which occurred for isoproturon, metalaxyl and bentazone. No breakthrough of linuron was observed, thus, this pesticide was appointed as the most retained and/or degraded pesticide, followed by isoproturon, metalaxyl and bentazone. Finally, most of the matrix mixes efficient in degrading or retaining pesticides were mixes containing dried cow manure. - Transport of pesticides in macrocosm containing organic substrates

  8. Characterizing pesticide sorption and degradation in macro scale biopurification systems using column displacement experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wilde, Tineke de [Laboratory of Crop Protection Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium)], E-mail: Tineke.DeWilde@UGent.be; Spanoghe, Pieter [Laboratory of Crop Protection Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Mertens, Jan; Sniegowksi, Kristel; Ryckeboer, Jaak [Division of Soil and Water Management, Faculty of Bioscience Engineering, K.U. Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee (Belgium); Jaeken, Peter [PCF-Royal Research Station of Gorsem, De Brede Akker 13, 3800 Sint-Truiden (Belgium); Springael, Dirk [Division of Soil and Water Management, Faculty of Bioscience Engineering, K.U. Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee (Belgium)

    2009-04-15

    The efficiency of biopurification systems to treat pesticide-contaminated water was previously studied in microcosms. To validate the obtained results, macrocosm systems were set-up. Four pesticides (linuron, isoproturon, bentazone, and metalaxyl) were continuously applied to ten different organic substrate mixes. Retention of the pesticides was similar and in some cases slightly lower in the macrocosms compared to the microcosms. Differences in retention between the different mixes were however minimal. Moreover, the classification of the retention strength of the pesticides was identical to that observed in microcosms: linuron > isoproturon > metalaxyl > bentazone. Monod kinetics were used to describe delayed degradation, which occurred for isoproturon, metalaxyl and bentazone. No breakthrough of linuron was observed, thus, this pesticide was appointed as the most retained and/or degraded pesticide, followed by isoproturon, metalaxyl and bentazone. Finally, most of the matrix mixes efficient in degrading or retaining pesticides were mixes containing dried cow manure. - Transport of pesticides in macrocosm containing organic substrates.

  9. Sorption behavior of cesium onto bentonite colloid

    International Nuclear Information System (INIS)

    Iijima, Kazuki; Masuda, Tsuguya; Tomura, Tsutomu

    2004-01-01

    It is considered that bentonite colloid might be generated from bentonite which will be used as buffer material in geological disposal system, and can facilitate the migration of radionuclides by means of sorption. In order to examine this characteristic, sorption and desorption experiments of Cs onto bentonite colloid were carried out to obtain its distribution coefficient (Kd) and information on the reversibility of its sorption. In addition, particle size distribution and shape of colloid were investigated and their effect on the sorption behavior was discussed. Kds for Cs were around 20 m 3 /kg for sorption and 30 m 3 /kg for desorption, in which sorbed Cs was desorbed by 8.4x10 -4 mol/l of NaCl solution. These values did not show any dependencies on Cs concentration and duration of sorption and desorption. The first 20% of sorbed Cs was desorbed reversibly at least. Most of colloidal particles were larger than 200 nm and TEM micrographs showed they had only several sheets of the clay crystal. Obtained Kds for colloidal bentonite were larger than those for powdered bentonite. This can be caused by difference of competing ions in the solution, characteristics of contained smectite, or sorption site density. (author)

  10. Development of High Capacity Split Stirling Cryocooler for HTS

    Science.gov (United States)

    Yumoto, Kenta; Nakano, Kyosuke; Hiratsuka, Yoshikatsu

    Sumitomo Heavy Industries, Ltd. (SHI) developed a high-power Stirling-type pulse tube cryocooler for cooling high-temperature superconductor (HTS) devices, such as superconductor motors, superconducting magnetic energy storage (SMES), and fault current limiters. The experimental results of a prototype pulse tube cryocooler were reported in September 2013. For a U-type expander, the cooling capacity was 151 W at 70 K with a compressor input power of 4 kW. Correspondingly, the coefficient of performance (COP) was about 0.038. However, the efficiency of the cryocooler is required to be COP > 0.1 and it was found that, theoretically, it is difficult to further improve the efficiency of a pulse tube cryocooler because the workflow generated at the hot end of the pulse tube cannot be recovered. Therefore, it was decided to change the expander to a free-piston type from a pulse tube type. A prototype was developed and preliminary experiments were conducted. A cooling capacity of 120 W at 70 K with a compressor input power of 2.15 kW with corresponding COP of 0.056, was obtained. The detailed results are reported in this paper.

  11. Operating single quantum emitters with a compact Stirling cryocooler.

    Science.gov (United States)

    Schlehahn, A; Krüger, L; Gschrey, M; Schulze, J-H; Rodt, S; Strittmatter, A; Heindel, T; Reitzenstein, S

    2015-01-01

    The development of an easy-to-operate light source emitting single photons has become a major driving force in the emerging field of quantum information technology. Here, we report on the application of a compact and user-friendly Stirling cryocooler in the field of nanophotonics. The Stirling cryocooler is used to operate a single quantum emitter constituted of a semiconductor quantum dot (QD) at a base temperature below 30 K. Proper vibration decoupling of the cryocooler and its surrounding enables free-space micro-photoluminescence spectroscopy to identify and analyze different charge-carrier states within a single quantum dot. As an exemplary application in quantum optics, we perform a Hanbury-Brown and Twiss experiment demonstrating a strong suppression of multi-photon emission events with g((2))(0) Stirling-cooled single quantum emitter under continuous wave excitation. Comparative experiments performed on the same quantum dot in a liquid helium (LHe)-flow cryostat show almost identical values of g((2))(0) for both configurations at a given temperature. The results of this proof of principle experiment demonstrate that low-vibration Stirling cryocoolers that have so far been considered exotic to the field of nanophotonics are an attractive alternative to expensive closed-cycle cryostats or LHe-flow cryostats, which could pave the way for the development of high-quality table-top non-classical light sources.

  12. Operating single quantum emitters with a compact Stirling cryocooler

    Energy Technology Data Exchange (ETDEWEB)

    Schlehahn, A.; Krüger, L.; Gschrey, M.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Heindel, T., E-mail: tobias.heindel@tu-berlin.de; Reitzenstein, S. [Institute of Solid State Physics, Technische Universität Berlin, 10623 Berlin (Germany)

    2015-01-15

    The development of an easy-to-operate light source emitting single photons has become a major driving force in the emerging field of quantum information technology. Here, we report on the application of a compact and user-friendly Stirling cryocooler in the field of nanophotonics. The Stirling cryocooler is used to operate a single quantum emitter constituted of a semiconductor quantum dot (QD) at a base temperature below 30 K. Proper vibration decoupling of the cryocooler and its surrounding enables free-space micro-photoluminescence spectroscopy to identify and analyze different charge-carrier states within a single quantum dot. As an exemplary application in quantum optics, we perform a Hanbury-Brown and Twiss experiment demonstrating a strong suppression of multi-photon emission events with g{sup (2)}(0) < 0.04 from this Stirling-cooled single quantum emitter under continuous wave excitation. Comparative experiments performed on the same quantum dot in a liquid helium (LHe)-flow cryostat show almost identical values of g{sup (2)}(0) for both configurations at a given temperature. The results of this proof of principle experiment demonstrate that low-vibration Stirling cryocoolers that have so far been considered exotic to the field of nanophotonics are an attractive alternative to expensive closed-cycle cryostats or LHe-flow cryostats, which could pave the way for the development of high-quality table-top non-classical light sources.

  13. Release and sorption of alkali metals in coal fired combined cycle power systems; Freisetzung und Einbindung von Alkalimetallverbindungen in kohlebefeuerten Kombikraftwerken

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Michael

    2009-07-01

    Coal fired combined cycle power systems will be a sufficient way to increase the efficiency of coal combustion. However, combined cycle power systems require a reliable hot gas cleanup. Especially alkali metals, such as sodium and potassium, can lead to hot corrosion of the gas turbine blading if they condensate as sulphates. The actual work deals with the release and sorption of alkali metals in coal fired combined cycle power systems. The influence of coal composition, temperature and pressure on the release of alkali species in coal combustion was investigated and the relevant release mechanisms identified. Alumosilicate sorbents have been found that reduce the alkali concentration in the hot flue gas of the Circulating Pressurized Fluidized Bed Combustion 2{sup nd} Generation (CPFBC 2{sup nd} Gen.) at 750 C to values sufficient for use in a gas turbine. Accordingly, alumosilicate sorbents working at 1400 C have been found for the Pressurized Pulverized Coal Combustion (PPCC). The sorption mechanisms have been identified. Thermodynamic calculations were performed to upscale the results of the laboratory experiments to conditions prevailing in power systems. According to these calculations, there is no risk of hot corrosion in both processes. Furthermore, thermodynamic calculations were performed to investigate the behaviour of alkali metals in an IGCC with integrated hot gas cleanup and H{sub 2} membrane for CO{sub 2} sequestration. (orig.)

  14. Sorption of Hg(II and Pb(II Ions on Chitosan-Iron(III from Aqueous Solutions: Single and Binary Systems

    Directory of Open Access Journals (Sweden)

    Byron Lapo

    2018-03-01

    Full Text Available The present work describes the study of mercury Hg(II and lead Pb(II removal in single and binary component systems into easily prepared chitosan-iron(III bio-composite beads. Scanning electron microscopy and energy-dispersive X-ray (SEM-EDX analysis, Fourier transform infrared spectroscopy (FTIR, thermogravimetric analysis (TGA and point of zero charge (pHpzc analysis were carried out. The experimental set covered pH study, single and competitive equilibrium, kinetics, chloride and sulfate effects as well as sorption–desorption cycles. In single systems, the Langmuir nonlinear model fitted the experimental data better than the Freundlich and Sips equations. The sorbent material has more affinity to Hg(II rather than Pb(II ions, the maximum sorption capacities were 1.8 mmol·g−1 and 0.56 mmol·g−1 for Hg(II and Pb(II, respectively. The binary systems data were adjusted with competitive Langmuir isotherm model. The presence of sulfate ions in the multicomponent system [Hg(II-Pb(II] had a lesser impact on the sorption efficiency than did chloride ions, however, the presence of chloride ions improves the selectivity towards Hg(II ions. The bio-based material showed good recovery performance of metal ions along three sorption–desorption cycles.

  15. Application of smart structure concepts to vibration suppression of a cryocooler coldfinger

    International Nuclear Information System (INIS)

    Glaser, R.J.; Kuo, Chinpo, Garba, J.A.

    1993-01-01

    A flight experiment demonstrating vibration suppression using smart structure technology is being flown on a small British satellite in late 1993. Piezo actuators are used to suppress motion of the tip of a cryocooler coldfinger in three dimensions. Two actuation methods are being demonstrated: low voltage piezo translators and applique ceramics. The applique ceramics stretch the coldfinger to cancel the tip motion and is discussed in detail in a companion paper. Commercially available piezo translators displace the entire cryocooler to cancel the motion of the tip of the coldfinger as measured by three eddy current transducers. Two types of control systems are being demonstrated: a real time analog control system using position feedback, and a digital feed forward controller that updates it's waveform every second or so. The flight experiment is a technology demonstration. The coldfinger is not being used to cool an operational sensor. Instead, the cooler vibration experiment will demonstrate that this class of hardware can be flown successfully. This includes qualification of the piezos for launch, and for the space environment; the design and qualification of low-power flight piezo drivers; and design and implementation of the control systems

  16. Sorption properties of wool

    Directory of Open Access Journals (Sweden)

    Radetić Maja M.

    2004-01-01

    Full Text Available Strict ecological legislation, especially in highly developed countries, imposed requirements for the purification of industrial effluents and the need for efficient oil clean up after sea and inland water spills. Although numerous processes have been developed, the application of sorbents is still one of the most efficient methods to remove heavy metal ions, dyes and crude oil from water. Recently, special attention was paid to sorbents based on natural fibres. A review of studies concerning the sorption properties of wool is presented in this paper. The presence of various functional groups on the wool fibre surface contributes to the efficient sorption of heavy metal ions and dyes. A hydrophobic, scaly surface and fibre crimp strongly influence the high sorption capacity of wool for oil. Wool has great sorption potential even as a recycled material. Accordingly, it can be used as a viable substitute to commercially available synthetic sorbents that show poor biodegradab ility.

  17. Migration and sorption phenomena in packaged foods.

    Science.gov (United States)

    Gnanasekharan, V; Floros, J D

    1997-10-01

    Rapidly developing analytical capabilities and continuously evolving stringent regulations have made food/package interactions a subject of intense research. This article focuses on: (1) the migration of package components such as oligomers and monomers, processing aids, additives, and residual reactants in to packaged foods, and (2) sorption of food components such as flavors, lipids, and moisture into packages. Principles of diffusion and thermodynamics are utilized to describe the mathematics of migration and sorption. Mathematical models are developed from first principles, and their applicability is illustrated using numerical simulations and published data. Simulations indicate that available models are system (polymer-penetrant) specific. Furthermore, some models best describe the early stages of migration/sorption, whereas others should be used for the late stages of these phenomena. Migration- and/or sorption-related problems with respect to glass, metal, paper-based and polymeric packaging materials are discussed, and their importance is illustrated using published examples. The effects of migrating and absorbed components on food safety, quality, and the environment are presented for various foods and packaging materials. The impact of currently popular packaging techniques such as microwavable, ovenable, and retortable packaging on migration and sorption are discussed with examples. Analytical techniques for investigating migration and sorption phenomena in food packaging are critically reviewed, with special emphasis on the use and characteristics of food-simulating liquids (FSLs). Finally, domestic and international regulations concerning migration in packaged foods, and their impact on food packaging is briefly presented.

  18. Sorption study of system soil/water solution of CsCl using 137Cs as a radio-indicator

    International Nuclear Information System (INIS)

    Varga, R.; Krajnakova, M.; Lesny, J.; Matusek, I.

    2003-01-01

    Mobility of the radiocesium in natural environment is a function of all scale of variables, including the time. The important factor that influences on the mobility is quality and quantity of loamy minerals in soils. This paper represents a study of sorption characteristics of soils of the object No. 41, which is in the area of the Jaslovske Bohunice NPP, for radiocesium, examined experimentally appointed adsorption isotherms according to Langmuir and Freundlich. The identical experiments with the montmorillonite K-10 were realized simultaneously for a comparison of the results. (authors)

  19. A novel method to hit the limit temperature of Stirling-type cryocooler

    Science.gov (United States)

    Wang, Jue; Pan, Changzhao; Zhang, Tong; Luo, Kaiqi; Zhou, Yuan; Wang, Junjie

    2018-02-01

    The Stirling-type cryocooler with its compact size and high efficiency is always expected to obtain its temperature limit of below 3 K. However, the pressure drop losses caused by high-frequency oscillation create large obstacles for this objective. This paper reports a novel thermal-driven Stirling-type cryocooler to obtain the lowest temperature of a Stirling-type cryocooler. The advantages of a thermal-driven cryocooler (Vuilleumier cryocooler) and pulse tube cryocooler are combined with a new type of cryocooler, called the Vuilleumier gas-coupling pulse tube hybrid cryocooler (VM-PT). A prototype of the VM-PT was recently developed and optimized in our laboratory. By using helium-4 as the working gas and magnetic regenerative materials (HoCu2 and Er3Ni), the lowest temperature of 2.5 K was obtained, which can be regarded as an important breakthrough for the Stirling-type cryocooler to achieve its limit temperature of below 3 K. It can supply >30 mW cooling power at 4.2 K and >500 mW cooling power at 20 K simultaneously. Theoretically, it is feasible to use this VM-PT for cooling the superconducting devices in space applications.

  20. Validation of accelerated ageing of Thales rotary Stirling cryocoolers for the estimation of MTTF

    Science.gov (United States)

    Seguineau, C.,; Cauquil, J.-M.; Martin, J.-Y.; Benschop, T.

    2016-05-01

    The cooled IR detectors are used in a wide range of applications. Most of the time, the cryocoolers are one of the components dimensioning the lifetime of the system. The current market needs tend to reliability figures higher than 15,000hrs in "standard conditions". Field returns are hardly useable mostly because of the uncertain environmental conditions of use, or the differences in user profiles. A previous paper explains how Thales Cryogenics has developed an approach based on accelerated ageing and statistical analysis [1]. The aim of the current paper is to compare results obtained on accelerated ageing on one side, and on the other side, specific field returns where the conditions of use are well known. The comparison between prediction and effective failure rate is discussed. Moreover, a specific focus is done on how some new applications of cryocoolers (continuous operation at a specific temperature) can increase the MTTF. Some assumptions are also exposed on how the failure modes, effects and criticality analysis evolves for continuous operation at a specific temperature and compared to experimental data.

  1. Evaluation of sorption capacity of scrap tyre in the removal of copper (II) ion from aqua system

    International Nuclear Information System (INIS)

    Oladoja, N.A.; Ofomaja, A.; Ebare, E.; Ebare, E.

    2006-01-01

    The use of scrap-tyre (ST), which was both a waste and pollutant was investigated as a low-cost sorbent to sorbed Cu (II) from aqueous solution. The influence of pH, sorbent dosage, contact time, and initial sorbate concentration on the uptake of Cu (II) by ST were studied. Optimum sorption of Cu (II) by ST was achieved at pH 6. The amount Of sorbate sorbed per gram of sorbent decreased with increase in sorbent dosage. Maximum uptake of the Cu (II) was achieved within the first thirty minutes of contact between the ST and the Cu (II). The equilibrium relationship between the concentration of the Cu (II) in the fluid phase and the concentration in the ST particles at a given temperature showed that the sorption mechanism was like adsorption rather than distribution into any phase. Analysis of the result using Langmuir and Freundlich models showed that it conformed to Langmuir equation based on the formation of a monomolecular layer. The adsorption capacity due to monolayer coverage was 12.95 mg/g, while the energy of adsorption was 3.95 dm/mg. (author)

  2. Base Catalytic Approach: A Promising Technique for the Activation of Biochar for Equilibrium Sorption Studies of Copper, Cu(II Ions in Single Solute System

    Directory of Open Access Journals (Sweden)

    Sharifah Bee Abdul Hamid

    2014-04-01

    Full Text Available This study examines the feasibility of catalytically pretreated biochar derived from the dried exocarp or fruit peel of mangostene with Group I alkali metal hydroxide (KOH. The pretreated char was activated in the presence of carbon dioxide gas flow at high temperature to upgrade its physiochemical properties for the removal of copper, Cu(II cations in single solute system. The effect of three independent variables, including temperature, agitation time and concentration, on sorption performance were carried out. Reaction kinetics parameters were determined by using linear regression analysis of the pseudo first, pseudo second, Elovich and intra-particle diffusion models. The regression co-efficient, R2 values were best for the pseudo second order kinetic model for all the concentration ranges under investigation. This implied that Cu(II cations were adsorbed mainly by chemical interactions with the surface active sites of the activated biochar. Langmuir, Freundlich and Temkin isotherm models were used to interpret the equilibrium data at different temperature. Thermodynamic studies revealed that the sorption process was spontaneous and endothermic. The surface area of the activated sample was 367.10 m2/g, whereas before base activation, it was only 1.22 m2/g. The results elucidated that the base pretreatment was efficient enough to yield porous carbon with an enlarged surface area, which can successfully eliminate Cu(II cations from waste water.

  3. Stirling cryocooler test results and design model verification

    International Nuclear Information System (INIS)

    Shimko, M.A.; Stacy, W.D.; McCormick, J.A.

    1990-01-01

    This paper reports on progress in developing a long-life Stirling cycle cryocooler for space borne applications. It presents the results from tests on a preliminary breadboard version of the cryocooler used to demonstrate the feasibility of the technology and to validate the regenerator design code used in its development. This machine achieved a cold-end temperature of 65 K while carrying a 1/2 Watt cooling load. The basic machine is a double-acting, flexure-bearing, split Stirling design with linear electromagnetic drives for the expander and compressors. Flat metal diaphragms replace pistons for both sweeping and sealing the machine working volumes. In addition, the double-acting expander couples to a laminar-channel counterflow recuperative heat exchanger for regeneration. A PC compatible design code was developed for this design approach that calculates regenerator loss including heat transfer irreversibilities, pressure drop, and axial conduction in the regenerator walls

  4. Multimodal tuned dynamic absorber for split Stirling linear cryocooler

    Science.gov (United States)

    Veprik, A.; Tuito, A.

    2017-02-01

    Forthcoming low size, weight, power and price split Stirling linear cryocoolers may rely on electro-dynamically driven single-piston compressors and pneumatically driven expanders interconnected by the configurable transfer line. For compactness, compressor and expander units may be placed in a side-by-side manner, thus producing tonal vibration export comprising force and moment components. In vibration sensitive applications, this may result in excessive angular line of sight jitter and translational defocusing affecting the image quality. The authors present Multimodal Tuned Dynamic Absorber (MTDA), having one translational and two tilting modes essentially tuned to the driving frequency. The dynamic reactions (force and moment) produced by such a MTDA are simultaneously counterbalancing force and moment vibration export produced by the cryocooler. The authors reveal the design details, the method of fine modal tuning and outcomes of numerical simulation on attainable performance.

  5. Development of Web-based Software for Sorption Database

    International Nuclear Information System (INIS)

    Han, Byoung Sub; Lee, Jae Min; Seo, Min Seok; Kim, Dong Keon

    2009-08-01

    Sorption studies of radionuclides are important parts of research on radioactive waste disposal which is commonly faced in most countries where nuclear programs (power production, a variety of peaceful applications, and research) are implemented. The Sorption Database (DB) plays a very important role in the safety assessment of the radioactive waste disposal. The Sorption DB which is opened externally can be used as reference material of establishing a national policy by improving and changing the pre-developed Sorption program to be web-based. From the industrial point of view, if the Sorption DB is opened to the outside, the safety-related confidence can be achieved for nuclear industry. As the information of Sorption DB is opened, not only credibility can be provided to the administration, local governments and nearby residents, but also input of the collected information can be achieved by online. In addition, the reference material and external awareness/reliability about the domestic level of the Sorption DB management system and the current state can be achieved internationally. In order to provide the information of Sorption DB to users in more efficient way, the analysis and complement of management and search capability for the existing Sorption DB program have been performed and web-based management system has been built to provide services to users. In addition, by applying statistical techniques, it has been designed and implemented to display the accuracy and error of the information

  6. Metal sorption on kaolinite

    International Nuclear Information System (INIS)

    Westrich, H.R.; Brady, P.V.; Cygan, R.T.; Nagy, K.L.; Anderson, H.L.

    1997-01-01

    A key issue in performance assessment of low-level radioactive waste sites is predicting the transport and retardation of radionuclides through local soils under a variety of hydrologic and geochemical conditions. Improved transport codes should include a mechanistic model of radionuclide retardation. The authors have been investigating metal sorption (Cs + , Sr 2+ , and Ba 2+ ) on a simple clay mineral (kaolinite) to better understand the geochemical interactions of common soil minerals with contaminated groundwaters. These studies include detailed characterizations of kaolinite surfaces, experimental adsorption measurements, surface complexation modeling, and theoretical simulations of cation sorption. The aluminol edge (010) site has been identified as the most likely site for metal sorption on kaolinite in natural solutions. Relative metal binding strengths decrease from Ba 2+ to Sr 2+ to Cs + , with some portion sorbed on both kaolinite edges and basal surfaces. Some Cs + also appears to be irreversibly sorbed on both sites. Molecular dynamics simulations suggest that Cs + is sorbed at aluminol (010) edge sites as an inner-sphere complex and weakly sorbed as an outer-sphere complex on (001) basal surfaces. These results provide the basis to understand and predict metal sorption onto kaolinite, and a framework to characterize sorption processes on more complex clay minerals

  7. Space Stirling Cryocooler Contamination Lessons Learned and Recommended Control Procedures

    Science.gov (United States)

    Glaister, D. S.; Price, K.; Gully, W.; Castles, S.; Reilly, J.

    The most important characteristic of a space cryocooler is its reliability over a lifetime typically in excess of 7 years. While design improvements have reduced the probability of mechanical failure, the risk of internal contamination is still significant and has not been addressed in a consistent approach across the industry. A significant fraction of the endurance test and flight units have experienced some performance degradation related to internal contamination. The purpose of this paper is to describe and assess the contamination issues inside long life, space cryocoolers and to recommend procedures to minimize the probability of encountering contamination related failures and degradation. The paper covers the sources of contamination, the degradation and failure mechanisms, the theoretical and observed cryocooler sensitivity, and the recommended prevention procedures and their impact. We begin with a discussion of the contamination sources, both artificial and intrinsic. Next, the degradation and failure mechanisms are discussed in an attempt to arrive at a contaminant susceptibility, from which we can derive a contamination budget for the machine. This theoretical sensitivity is then compared with the observed sensitivity to illustrate the conservative nature of the assumed scenarios. A number of lessons learned on Raytheon, Ball, Air Force Research Laboratory, and NASA GSFC programs are shared to convey the practical aspects of the contamination problem. Then, the materials and processes required to meet the proposed budget are outlined. An attempt is made to present a survey of processes across industry.

  8. Observation of quantized vortices by cryocooler-based scanning Hall probe microscope

    Energy Technology Data Exchange (ETDEWEB)

    Tokunaga, Y.; Konishi, Y.; Tokunaga, M.; Tamegai, T

    2004-10-01

    We have developed a scanning Hall probe microscope (SHPM) system utilizing closed-cycle cryocooler. The Hall probe used in this system is fabricated from a GaAs/GaAlAs two-dimensional electron gas. A stepping-motor-driven XYZ translator is used with a resolution better than 0.1 {mu}m and maximum scan range of 20 x 20 mm{sup 2}. The spatial resolution of the system is about 5 {mu}m and magnetic resolution is about 100 mG. By using this system, we have successfully resolved the quantized vortices on the cleaved surface of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+y} single crystal.

  9. Influence of selected factors on strontium sorption on bentonites

    International Nuclear Information System (INIS)

    Galambos, M.; Kufcakova, J.; Rajec, P.

    2007-01-01

    Sorption on bentonite will play an important role in retarding the migration of radionuclides from a waste repository. Bentonite is a natural clay and one of the most promising candidates for use as a buffer material in the geological disposal systems for high-level nuclear waste. It is intended to isolate metal canisters with highly radioactive waste products from the surrounding rocks because of its ability to retard the movement of radionuclides by sorption. Bentonite is characterized by low permeability, water swelling capability and excellent sorption potential for cationic radionuclides. To correctly assess the sorption potential of radionuclides on bentonite is essential for the development of predictive migration models. The sorption of strontium on bentonite from different Slovak deposits - Jelsovy potok, Kopernica and Lieskovec has been investigated under various experimental conditions, such as contact time, sorbate concentrations, presence of complementary cation. Sorption was studied using the batch technique. The uptake of Sr was rapid and equilibrium was reached almost instantaneously. The instantaneous uptake may be due to adsorption and/or exchange of the metal with some ions on the surface of the adsorbent. The best sorption characteristics distinguish bentonite Kopernica, sorption capacity for Sr of the fraction under 45 mm is 0,48 mmol·g -1 for Sr. The highest values of distribution coefficient were reached for the bentonite Jelsovy potok. Radiation stability has been investigated, the higher sorption parameters were observed for the irradiated bentonites, which can be explained by the increase of specific surface of the bentonite samples. The presence of complementary cations depresses the sorption of Sr on bentonite. Cations Ca 2+ exhibit higher effect on cesium sorption than the Na 2+ ions. Results indicate that the sorption of Sr 2+ on bentonite will be affected by the presence of high concentrations of various salts in the waste water

  10. Performance degradation of space Stirling cryocoolers due to gas contamination

    Science.gov (United States)

    Liu, Xin-guang; Wu, Yi-nong; Yang, Shao-hua; Zhang, Xiao-ming; Lu, Guo-hua; Zhang, Li

    2011-08-01

    With extensive application of infrared detective techniques, Stirling cryocoolers, used as an active cooling source, have been developed vigorously in China. After the cooler's cooling performance can satisfy the mission's request, its reliability level is crucial for its application. Among all the possible failure mechanisms, gas contamination has been found to be the most notorious cause of cooler's performance degradation by failure analyses. To analyze the characteristic of gas contamination, some experiments were designed and carried out to quantitatively analyze the relationship between failure and performance. Combined with the test results and the outgassing characteristic of non-metal materials in the cryocooler, a degradation model of cooling performance was given by T(t)=T0+A[1-exp(-t/B)] under some assumptions, where t is the running time, T is the Kelvin cooling temperature, and T0, A, B are model parameters, which can be given by the least square method. Here T0 is the fitting initial cooling temperature, A is the maximum range of performance degradation, and B is the time dependent constant of degradation. But the model parameters vary when a cryocooler is running at different cooling temperature ranges, or it is treated by different cleaning process. In order to verify the applicability of the degradation model, data fit analysis on eight groups of cooler's lifetime test was carried out. The final work indicated this model fit well with the performance degradation of space Stirling cryocoolers due to gas contamination and this model could be used to predict or evaluation the cooler's lifetime. Gaseous contamination will not arouse severe performance degradation until the contaminants accumulate to a certain amount, but it could be fatal when it works. So it is more serious to the coolers whose lifetime is more than 10,000 h. The measures taken to control or minimize its damage were discussed as well. To the long-life cryocooler, internal materials

  11. Effects of sorption behaviour on contaminant migration

    International Nuclear Information System (INIS)

    Melnyk, T.W.

    1985-11-01

    The effects of sorption behaviour on contaminant migration in groundwater systems are varied. Retardation of migration and dispersive effects can vary widely and contaminant concentration profiles can take a number of different shapes. This report examines the nature of some of these effects, especially those due to sorption behaviours that are dependent on the concentration of the contaminant in the groundwater. The effects are calculated using, in most cases, analytical solutions to the chemical equations imbedded in a simple reaction-cell or box-model transport algorithm. The hydrogeological parameters are held constant, and radioactive decay and hydrodynamic dispersion are excluded. A general discussion of the role of sorption equations in transport modelling is followed by presentation of migration results for a number of models of sorption behaviour varying from linear isotherms, Langmuir, Freundlich and ion-exchange isotherms, to precipitation reactions and multiple-site sorption reactions. The results are compared and general conclusions are drawn about the various migration behaviours calculated. The conclusions are that equilibrium sorption of trace contaminants can be modelled with linear isotherms (constant distribution coefficients or constant retardation factors) but the evaluation and extrapolation of the distribution coefficient are not easy. Nonlinear isotherms lead to unsymmetrical migration fronts. A comparison of Freundlich and linear isotherms is made. Sorption/desorption kinetic factors can be significant on the time scale of laboratory experiments and can cause large dispersive effects. Slow but important reactions can be missed altogether. Precipitation or mineralization behaviour cannot be modelled with constant distribution coefficients. Also, mineralization reactions can be kinetically slow even on the geological time scale. 89 refs

  12. Computer simulation of molecular sorption in zeolites

    International Nuclear Information System (INIS)

    Calmiano, Mark Daniel

    2001-01-01

    The work presented in this thesis encompasses the computer simulation of molecular sorption. In Chapter 1 we outline the aims and objectives of this work. Chapter 2 follows in which an introduction to sorption in zeolites is presented, with discussion of structure and properties of the main zeolites studied. Chapter 2 concludes with a description of the principles and theories of adsorption. In Chapter 3 we describe the methodology behind the work carried out in this thesis. In Chapter 4 we present our first computational study, that of the sorption of krypton in silicalite. We describe work carried out to investigate low energy sorption sites of krypton in silicalite where we observe krypton to preferentially sorb into straight and sinusoidal channels over channel intersections. We simulate single step type I adsorption isotherms and use molecular dynamics to study the diffusion of krypton and obtain division coefficients and the activation energy. We compare our results to previous experimental and computational studies where we show our work to be in good agreement. In Chapter 5 we present a systematic study of the sorption of oxygen and nitrogen in five lithium substituted zeolites using a transferable interatomic potential that we have developed from ab initio calculations. We show increased loading of nitrogen compared to oxygen in all five zeolites studied as expected and simulate adsorption isotherms, which we compare to experimental and simulated data in the literature. In Chapter 6 we present work on the sorption of ferrocene in the zeolite NaY. We show that a simulated, low energy sorption site for ferrocene is correctly located by comparing to X-ray powder diffraction results for this same system. The thesis concludes with some overall conclusions and discussion of opportunities for future work. (author)

  13. Recent progress in sorption mechanisms and models

    International Nuclear Information System (INIS)

    Fedoroff, M.; Lefevre, G.

    2005-01-01

    Full text of publication follows: Sorption-desorption phenomena play an important role in the migration of radioactive species in surface and underground waters. In order to predict the transport of these species, we need a good knowledge of sorption processes and data, together with reliable models able to be included in transport calculation. Traditional approaches based on experimentally determined distribution coefficients (Kd) and sorption isotherms have a limited predictive capability, since they are very sensitive to the numerous parameters characterizing the solution and the solid. Models based on thermodynamic equilibria were developed to account for the influence these parameters: the ion exchange model and the surface complexation models (2-pK mono-site, 1-pK multi-site, with several different electrostatic models: CCM, DLM, BSM, TLM,...). Although these models are very useful, studies performed in recent years showed that they have important theoretical and experimental limitations, which result in the fact that we must be very careful when we use them for extrapolating sorption data to long term and to large natural systems. Among all problems which can be found are: the possibility to fit a set of experimental data with different models, sometimes bad adequacy with the real sorption processes, some theoretical limitations such as a rigorous definition of reference and standard states in surface equilibria, slow kinetics which prevent from equilibrium achievement, irreversibility, solubility and evolution of solid phases... Through the increase of the number of sensitive spectroscopic methods, we are now able to know more about sorption processes at the atomic scale. Models such as the 1-pK CD-MUSIC model can account for the influence of orientation of the faces of the solid. More and more examples of the influence of this orientation on the sorption properties are known. Calculations performed by 'ab initio' modeling is also useful to predict the

  14. Competitive sorption of heavy metals by water hyacinth roots.

    Science.gov (United States)

    Zheng, Jia-Chuan; Liu, Hou-Qi; Feng, Hui-Min; Li, Wen-Wei; Lam, Michael Hon-Wah; Lam, Paul Kwan-Sing; Yu, Han-Qing

    2016-12-01

    Heavy metal pollution is a global issue severely constraining aquaculture practices, not only deteriorating the aquatic environment but also threatening the aquaculture production. One promising solution is adopting aquaponics systems where a synergy can be established between aquaculture and aquatic plants for metal sorption, but the interactions of multiple metals in such aquatic plants are poorly understood. In this study, we investigated the absorption behaviors of Cu(II) and Cd(II) in water by water hyacinth roots in both single- and binary-metal systems. Cu(II) and Cd(II) were individually removed by water hyacinth roots at high efficiency, accompanied with release of protons and cations such as Ca 2+ and Mg 2+ . However, in a binary-metal arrangement, the Cd(II) sorption was significantly inhibited by Cu(II), and the higher sorption affinity of Cu(II) accounted for its competitive sorption advantage. Ionic exchange was identified as a predominant mechanism of the metal sorption by water hyacinth roots, and the amine and oxygen-containing groups are the main binding sites accounting for metal sorption via chelation or coordination. This study highlights the interactive impacts of different metals during their sorption by water hyacinth roots and elucidates the underlying mechanism of metal competitive sorption, which may provide useful implications for optimization of phytoremediation system and development of more sustainable aquaculture industry. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Performance analysis on free-piston Stirling cryocooler based on an idealized mathematical model

    Science.gov (United States)

    Guo, Y. X.; Chao, Y. J.; Gan, Z. H.; Li, S. Z.; Wang, B.

    2017-12-01

    Free-piston Stirling cryocoolers have extensive applications for its simplicity in structure and decrease in mass. However, the elimination of the motor and the crankshaft has made its thermodynamic characteristic different from that of Stirling cryocoolers with displacer driving mechanism. Therefore, an idealized mathematical model has been established, and with this model, an attempt has been made to analyse the thermodynamic characteristic and the performance of free-piston Stirling cryocooler. To certify this mathematical model, a comparison has been made between the model and a numerical model. This study reveals that due to the displacer damping force necessary for the production of cooling capacity, the free-piston Stirling cryocooler is inherently less efficient than Stirling cryocooler with displacer driving mechanism. Viscous flow resistance and incomplete heat transfer in the regenerator are the two major causes of the discrepancy between the results of the idealized mathematical model and the numerical model.

  16. The NEA sorption data base (SDB)

    International Nuclear Information System (INIS)

    Ruegger, B.; Ticknor, K.

    1992-01-01

    The current NEA Sorption Data Base is developed to replace the former International Sorption Information Retrieval System (ISIRS) initiated at Pacific Northwest Laboratory and contains about 11,000 distribution coefficients with corresponding experimental condition parameters describing sorption of key nuclides for a large variety of solid and liquid phases. The SDB is designed to run on a micro-computer using the commercially available database software dBASE III Plus. For each recorded sorption experiment, the SDB provides a bibliographical reference, the most complete characterization of the solid and liquid phases available, a description of the experimental conditions and the distribution coefficient or retardation factor for each element studied. When available, parameters such as temperature, initial radionuclide concentration, pH, Eh, contact time, solid to solution ratio, sample origin, oxidation state and type of solution are included. The SDB provides information for a wide variety of rocks or geological materials, buffer backfill candidates, concretes/cements, elements (Am, Cs, Co, I, Np, Pu, Ra, Sr, Se, Tc, U and, to a lesser extent, Ag, Ba, C, Ce, Eu, Fe, Mn, Mo, Na, Nb, Ni, Pd, Pm, Ru, Sb, Sn, Y, Zn, and Zr), or radioisotopes. A compilation of sorption data like SDB provide a readily available source of data for radioactive waste repository performance assessments when site specific data are not available or essential, for example, during a site selection phase. 2 appendices

  17. Radionuclide sorption from the safety evaluation perspective

    International Nuclear Information System (INIS)

    1992-01-01

    Research and development directed towards the assessment of the long-term performance of radioactive waste disposal systems has been recognised as a priority area with a strong need for international co-operation and co-ordination. The ultimate aims is to promote the quality and credibility of safety assessment techniques for radioactive waste disposal. Sorption in the geosphere is one of the key processes for retarding the transport of radionuclide from the underground disposal facility to the biosphere. In many cases, sorption in the near field and in the biosphere is also important. A workshop, organised to favor discussion around a small number of invited papers, was held in October 1991: - to evaluate critically the way sorption processes are incorporated in performance assessment models; - to identify open issues of high priority, and; - to propose future activities to resolve these issues. These proceedings reproduce the invited papers and the conclusions and recommendations adopted by the workshop. Eight papers are in the INIS SCOPE. The main subjects studied are: sorption database comparison, sorption database development and three case studies, experimental techniques, adsorption models

  18. Numerical analysis of coupled water transport in wood with a focus on the coupling parameter sorption

    DEFF Research Database (Denmark)

    Hozjan, T.; Turk, G.; Rodman, U.

    2011-01-01

    This paper presents a study of sorption rate function in a so-called multi-Fickian or multi-phase model. This model describes the complex moisture transport system in wood, which consists of separate water-vapour and bound-water diffusion interacting through sorption. In the numerical example inf...... influence of the sorption rate function on water transport is presented. It can be seen that the sorption rate function has a noticeable influence on coupled water transport in wood....

  19. Transport and sorption of volatile organic compounds and water vapor in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Tsair-Fuh [Univ. of California, Berkeley, CA (United States)

    1995-07-01

    To gain insight on the controlling mechanisms for VOC transport in porous media, the relations among sorbent properties, sorption equilibrium and intraparticle diffusion processes were studied at the level of individual sorbent particles and laboratory columns for soil and activated carbon systems. Transport and sorption of VOCs and water vapor were first elucidated within individual dry soil mineral grains. Soil properties, sorption capacity, and sorption rates were measured for 3 test soils; results suggest that the soil grains are porous, while the sorption isotherms are nonlinear and adsorption-desorption rates are slow and asymmetric. An intragranular pore diffusion model coupled with the nonlinear Freundlich isotherm was developed to describe the sorption kinetic curves. Transport of benzene and water vapor within peat was studied; partitioning and sorption kinetics were determined with an electrobalance. A dual diffusion model was developed. Transport of benzene in dry and moist soil columns was studied, followed by gaseous transport and sorption in activated carbon. The pore diffusion model provides good fits to sorption kinetics for VOCs to soil and VOC to granular activated carbon and activated carbon fibers. Results of this research indicate that: Intraparticle diffusion along with a nonlinea sorption isotherm are responsible for the slow, asymmetric sorption-desorption. Diffusion models are able to describe results for soil and activated carbon systems; when combined with mass transfer equations, they predict column breakthrough curves for several systems. Although the conditions are simplified, the mechanisms should provide insight on complex systems involving transport and sorption of vapors in porous media.

  20. 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)

  1. Radionuclide sorption kinetics and column sorption studies with Columbia River basalts

    International Nuclear Information System (INIS)

    Barney, G.S.

    1983-09-01

    The kinetics of radionuclide sorption and desorption reactions in basalt-groundwater systems were evaluated at 60 degrees C using a batch equilibration method. It was found that many sorption reactions on surfaces of fresh (unaltered) basalt from the Umtanum and Cohassett flows are slow. Some reactions require more than 50 days to reach a steady state. Sorption of neptunium and uranium in oxidizing (air saturated) groundwater appears to be controlled by slow reduction of these elements by the basalt surfaces. The resulting lower oxidation states are more strongly sorbed. Technetium and selenium, which are anionic under oxidizing conditions, are not measurably sorbed on fresh basalt surfaces, but are slightly sorbed on the altered surfaces of flow top basalt. Under reducing conditions, where the groundwater contains dilute hydrazine, sorption is faster for neptunium, uranium, technetium, selenium, and lead. Plutonium sorption rates were not affected by the groundwater Eh. It was shown that radium was precipitated rather than sorbed under the conditions of these experiments. Umtanum flow top material sorbed radionuclides much faster than fresh basalt surfaces due to its greater surface area and cation exchange capacity. Desorption rates for plutonium, uranium, neptunium, technetium, and selenium were generally much less than sorption rates (especially for reducing conditions). These radionuclides are irreversibly sorbed on the basalts. 25 refs., 20 figs., 19 tabs

  2. Kinetics and reversibility of micropollutant sorption in sludge.

    Science.gov (United States)

    Barret, Maialen; Carrère, Hélène; Patau, Mathieu; Patureau, Dominique

    2011-10-01

    The fate of micropollutants throughout wastewater treatment systems is highly dependent on their sorption interactions with sludge matter. In this study, both the sorption and desorption kinetics of polycyclic aromatic hydrocarbons (PAHs) in activated sludge were shown to be very rapid in comparison to biodegradation kinetics. It was concluded that PAH transfer does not limit their biodegradation and that their fate is governed by the sorption/desorption equilibrium state. The effect of contact time between sludge and PAHs was also investigated. It was shown that aging did not influence the sorption/desorption equilibrium although PAH losses during aging suggest that sequestration phenomena had occurred. This implies that for PAH sorption assessment within treatment processes there is no need to include a contact time dimension. As a consequence, thanks to an innovative approach taking into account sorption equilibria and sequestration, this work has demonstrated that studies in the literature which, in main, deal with micropollutant sorption in sewage sludge with only a short contact time can be extrapolated to real systems in which sorption, desorption and aging occur.

  3. Cycle Design of Reverse Brayton Cryocooler for HTS Cable Cooling Using Exergy Analysis

    Science.gov (United States)

    Gupta, Sudeep Kumar; Ghosh, Parthasarathi

    2017-02-01

    The reliability and price of cryogenic refrigeration play an important role in the successful commercialization of High Temperature Superconducting (HTS) cables. For cooling HTS cable, sub-cooled liquid nitrogen (LN2) circulation system is used. One of the options to maintain LN2 in its sub-cooled state is by providing refrigeration with the help of Reverse Brayton Cryo-cooler (RBC). The refrigeration requirement is 10 kW for continuously sub-cooling LN2 from 72 K to 65 K for cooling 1 km length of HTS cable [1]. In this paper, a parametric evaluation of RBC for sub-cooling LN2 has been performed using helium as a process fluid. Exergy approach has been adopted for this analysis. A commercial process simulator, Aspen HYSYS® V8.6 has been used for this purpose. The critical components have been identified and their exergy destruction and exergy efficiency have been obtained for a given heat load condition.

  4. Cryocooled wideband digital channelizing radio-frequency receiver based on low-pass ADC

    International Nuclear Information System (INIS)

    Vernik, Igor V; Kirichenko, Dmitri E; Dotsenko, Vladimir V; Miller, Robert; Webber, Robert J; Shevchenko, Pavel; Talalaevskii, Andrei; Gupta, Deepnarayan; Mukhanov, Oleg A

    2007-01-01

    We have demonstrated a digital receiver performing direct digitization of radio-frequency signals over a wide frequency range from kilohertz to gigahertz. The complete system, consisting of a cryopackaged superconductor all-digital receiver (ADR) chip followed by room-temperature interface electronics and a field programmable gate array (FPGA) based post-processing module, has been developed. The ADR chip comprises a low-pass analog-to-digital converter (ADC) delta modulator with phase modulation-demodulation architecture together with digital in-phase and quadrature mixer and a pair of digital decimation filters. The chip is fabricated using a 4.5 kA cm -2 process and is cryopackaged using a commercial-off-the-shelf cryocooler. Experimental results in HF, VHF, UHF and L bands and their analysis, proving consistent operation of the cryopackaged ADR chip up to 24.32 GHz clock frequency, are presented and discussed

  5. Thermodynamic sorption modelling in support of radioactive waste disposal safety cases - NEA sorption project phase III

    International Nuclear Information System (INIS)

    2012-01-01

    and uncertainty analysis; 4. Approaches for applying TSMs to intact and complex materials: Introduction; Real substrates (What makes them complex?); Determination and estimation of TSM parameters in real systems; TSM application for Kd estimation on chemically complex substrates; Sorption modelling in clay rocks and compacted clay systems; TSM applications to crystalline host rocks; Application of generalised TSMs to complex and intact materials: concluding remarks and key messages; 5 - General guidelines and recommendations: Framework for TSM applications in the context of radioactive waste disposal; Purposes and predictive capabilities of TSMs; Strategies for building TSMs; Recommendations; Building a scientifically defensible, calibrated TSM for radioactive waste applications; Concluding comments; 6 - References; 7 - Annexes: List of authors and external experts; List of acronyms

  6. Development of a microminiature sorption cooler

    NARCIS (Netherlands)

    Burger, Johannes; Holland, Harry; ter Brake, Marcel; Rogalla, Horst; Wade, Larry

    1997-01-01

    The development of a microcooler for operations below 80 K, for low temperature electronic devices requiring small cooling powers of the order of 10 mW is described. A sorption compressor combined with Joule-Thomson (JT) expansion was selected for miniaturization. The advantage of the system is

  7. Tritium sorption on protective coatings for concrete

    International Nuclear Information System (INIS)

    Miller, J.M.; Senohrabek, J.A.; Allsop, P.A.

    1992-11-01

    Because of the high sorption level of tritium on unprotected concrete, a program to examine the effectiveness of various concrete coatings and sealants in reducing tritium sorption was undertaken, and various exposure conditions were examined. Coatings of epoxy, polyurethane, bituminous sealant, bituminous sealant covered with polyvinylidene chloride wrap, alkyd paint, and sodium silicate were investigated with tritium (HTO) vapor concentration, humidity and contact time being varied. An exposure to HT was also carried out, and the effect of humidity on the tritium desorption rate was investigated. The relative effectiveness of the coatings was in the order of bituminous sealant + wrap > bituminous sealant > solvent-based epoxy > 100%-solids epoxy > alkyd paint > sodium silicate. The commercially available coatings for concrete resulted in tritium sorption being reduced to less than 7% of unprotected concrete. This was improved to ∼0.1% with the use of the Saran wrap (polyvinylidene chloride). The amount of tritium sorbed was proportional to tritium concentration. The total tritium sorbed decreased with an increase in humidity. A saturation effect was observed with increasing exposure time for both the coated and unprotected samples. Under the test conditions, complete saturation was not achieved within the maximum 8-hour contact time, except for the solvent-based epoxy. The desorption rate increased with a higher-humidity air purge stream. HT desorbed more rapidly than HTO, but the amount sorbed was smaller. The experimental program showed that HTO sorption by concrete can be significantly reduced with the proper choice of coating. However, tritium sorption on concrete and proposed coatings will continue to be a concern until the effects of the various conditions that affect the adsorption and desorption of tritium are firmly established for both chronic and acute tritium release conditions. Material sorption characteristics must also be considered in

  8. Technetium Sorption Media Review

    International Nuclear Information System (INIS)

    Duncan, J.B.; Kelly, S.E.; Robbins, R.A.; Adams, R.D.; Thorson, M.A.; Haass, C.C.

    2011-01-01

    This report presents information and references to aid in the selection of 99Tc sorption media for feasibility studies regarding the removal of 99Tc from Hanford's low activity waste. The report contains literature search material for sorption media (including ion exchange media) for the most tested media to date, including SuperLig 639, Reillex HPQ, TAM (Kruion), Purolite A520E and A530E, and Dowex 1X8. The U.S. Department of Energy (DOE), Office of River Protection (ORP) is responsible for management and completion of the River Protection Project (RPP) mission, which comprises both the Hanford Site tank farms and the Waste Treatment and Immobilization Plant (WTP). The RPP mission is to store, retrieve and treat Hanford's tank waste; store and dispose of treated wastes; and close the tank farm waste management areas and treatment facilities in a safe, environmentally compliant, cost-effective and energy-effective manner.

  9. TECHNETIUM SORPTION MEDIA REVIEW

    Energy Technology Data Exchange (ETDEWEB)

    DUNCAN JB; KELLY SE; ROBBINS RA; ADAMS RD; THORSON MA; HAASS CC

    2011-08-25

    This report presents information and references to aid in the selection of 99Tc sorption media for feasibility studies regarding the removal of 99Tc from Hanford's low activity waste. The report contains literature search material for sorption media (including ion exchange media) for the most tested media to date, including SuperLig 639, Reillex HPQ, TAM (Kruion), Purolite A520E and A530E, and Dowex 1X8. The U.S. Department of Energy (DOE), Office of River Protection (ORP) is responsible for management and completion of the River Protection Project (RPP) mission, which comprises both the Hanford Site tank farms and the Waste Treatment and Immobilization Plant (WTP). The RPP mission is to store, retrieve and treat Hanford's tank waste; store and dispose of treated wastes; and close the tank farm waste management areas and treatment facilities in a safe, environmentally compliant, cost-effective and energy-effective manner.

  10. Effect of humic acid on sorption of technetium by alumina

    International Nuclear Information System (INIS)

    Kumar, S.; Rawat, N.; Kar, A.S.; Tomar, B.S.; Manchanda, V.K.

    2011-01-01

    Highlights: → Tc sorption on alumina has been studied under aerobic as well anaerobic condition over pH 3-10. → Effect of humic acid on sorption of Tc by alumina has been investigated. → Linear additive modeling and surface complexation modeling were carried out to delineate the role of humic acid in Tc(IV) sorption in ternary system of Tc(IV)-humic acid-alumina. → Sorption of humic acid onto alumina and strong complexation of Tc(IV) with humic acid were found to govern the sorption of Tc(IV) in the ternary system. - Abstract: Sorption of technetium by alumina has been studied in absence as well as in presence of humic acid using 95 Tc m as a tracer. Measurements were carried out at fixed ionic strength (0.1 M NaClO 4 ) under varying pH (3-10) as well as redox (aerobic and reducing anaerobic) conditions. Under aerobic conditions, negligible sorption of technetium was observed onto alumina both in absence and in presence of humic acid. However, under reducing conditions (simulated with [Sn(II)] = 10 -6 M), presence of humic acid enhanced the sorption of technetium in the low pH region significantly and decreased at higher pH with respect to that in absence of humic acid. Linear additive as well as surface complexation modeling of Tc(IV) sorption in presence of humic acid indicated the predominant role of sorbed humic acid in deciding technetium sorption onto alumina.

  11. Effects of cyclic mean pressure of helium gas on performance of integral crank driven stirling cryocooler

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je [Korea Institute of Machinery and Materials, Changwon (Korea, Republic of)

    2016-09-15

    An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space.

  12. Effects of cyclic mean pressure of helium gas on performance of integral crank driven stirling cryocooler

    International Nuclear Information System (INIS)

    Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je

    2016-01-01

    An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space

  13. Air Force Research Laboratory Spacecraft Cryocooler Endurance Evaluation Facility Closing Report

    Science.gov (United States)

    Armstrong, J.; Martin, K. W.; Fraser, T.

    2015-12-01

    The Air Force Research Laboratory (AFRL) Spacecraft Component Thermal Research Group has been devoted to evaluating lifetime performance of space cryocooler technology for over twenty years. Long-life data is essential for confirming design lifetimes for space cryocoolers. Continuous operation in a simulated space environment is the only accepted method to test for degradation. AFRL has provided raw data and detailed evaluations to cryocooler developers for advancing the technology, correcting discovered deficiencies, and improving cryocooler designs. At AFRL, units of varying design and refrigeration cycles were instrumented in state-of-the-art experiment stands to provide spacelike conditions and were equipped with software data acquisition to track critical cryocooler operating parameters. This data allowed an assessment of the technology's ability to meet the desired lifetime and documented any long-term changes in performance. This paper will outline a final report of the various flight cryocoolers tested in our laboratory. The data summarized includes the seven cryocoolers tested during 2014-2015. These seven coolers have a combined total of 433,326 hours (49.5 years) of operation.

  14. A pulse tube cryocooler with a cold reservoir

    Science.gov (United States)

    Zhang, X. B.; Zhang, K. H.; Qiu, L. M.; Gan, Z. H.; Shen, X.; Xiang, S. J.

    2013-02-01

    Phase difference between pressure wave and mass flow is decisive to the cooling capacity of regenerative cryocoolers. Unlike the direct phase shifting using a piston or displacer in conventional Stirling or GM cryocoolers, the pulse tube cyocooler (PTC) indirectly adjusts the cold phase due to the absence of moving parts at the cold end. The present paper proposed and validated theoretically and experimentally a novel configuration of PTC, termed cold reservoir PTC, in which a reservoir together with an adjustable orifice is connected to the cold end of the pulse tube. The impedance from the additional orifice to the cold end helps to increase the mass flow in phase with the pressure wave at the cold end. Theoretical analyses with the linear model for the orifice and double-inlet PTCs indicate that the cooling performance can be improved by introducing the cold reservoir. The preliminary experiments with a home-made single-stage GM PTC further validated the results on the premise of minor opening of the cold-end orifice.

  15. Sorption of actinides onto nanodiamonds

    Energy Technology Data Exchange (ETDEWEB)

    Buchatskaya, Yulia; Romanchuk, Anna; Yakovlev, Ruslan; Kulakova, Inna [Lomonosov Moscow State Univ., Moscow (Russian Federation). Dept. of Chemistry; Shiryaev, Andrei [Russian Academy of Sciences, Moscow (Russian Federation). Frumkin Institute of Physical Chemistry and Electrochemistry; Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry; Kalmykov, Stepan [Lomonosov Moscow State Univ., Moscow (Russian Federation). Dept. of Chemistry; Russian Academy of Sciences, Moscow (Russian Federation). Frumkin Institute of Physical Chemistry and Electrochemistry; Russian Academy of Sciences, Moscow (Russian Federation). Vernadsky Institute of Geochemistry and Analytical Chemistry

    2015-06-01

    Detonation nanodiamonds (ND) present a significant part of nanocarbons group, which could be produced on commercial scale by detonation of explosives in a closed chamber. Their unique properties of high surface area, low weight and radiation resistance make ND a prospective candidate for applications in sorption processes in radiochemistry. To study the influence of surface chemistry on sorption properties, apristine sample of ND was treated with acids and hydrogen. The surface chemistry of the samples was characterised by infrared spectroscopy, X-ray photoelectron spectroscopy and Boehm titration. The sorption properties of ND were tested fordifferent radionuclides. The sorption capacity of ND was shown to be higher than those of commonly used radionuclide sorbents like activated carbon and compariable to other members of nanocarbon group like graphene oxide and carbon nanotubes. The sorption properties were shown to be influenced by the presence of oxygen-containing groups on the surface of ND. This represents an opportunity to increase the sorption capacity of ND.

  16. Sorption of actinides onto nanodiamonds

    International Nuclear Information System (INIS)

    Buchatskaya, Yulia; Romanchuk, Anna; Yakovlev, Ruslan; Kulakova, Inna; Shiryaev, Andrei; Russian Academy of Sciences, Moscow; Kalmykov, Stepan; Russian Academy of Sciences, Moscow; Russian Academy of Sciences, Moscow

    2015-01-01

    Detonation nanodiamonds (ND) present a significant part of nanocarbons group, which could be produced on commercial scale by detonation of explosives in a closed chamber. Their unique properties of high surface area, low weight and radiation resistance make ND a prospective candidate for applications in sorption processes in radiochemistry. To study the influence of surface chemistry on sorption properties, apristine sample of ND was treated with acids and hydrogen. The surface chemistry of the samples was characterised by infrared spectroscopy, X-ray photoelectron spectroscopy and Boehm titration. The sorption properties of ND were tested fordifferent radionuclides. The sorption capacity of ND was shown to be higher than those of commonly used radionuclide sorbents like activated carbon and compariable to other members of nanocarbon group like graphene oxide and carbon nanotubes. The sorption properties were shown to be influenced by the presence of oxygen-containing groups on the surface of ND. This represents an opportunity to increase the sorption capacity of ND.

  17. Hydrogen sorption properties of the Lasub(1-x)Casub(x)Ni5 and La(Nisub(1-x)Cusub(x))5 systems

    International Nuclear Information System (INIS)

    Shinar, J.; Shaltiel, D.; Davidov, D.; Grayevsky, A.

    1978-01-01

    The hydrogen sorption properties of the Lasub(1-x)Casub(x)Ni 5 and La(Nisub(1-x)Cusub(x)) 5 systems were investigated at various temperatures and at pressures up to 20 atm. It was found that initial substitution of La by Ca in LaNi 5 caused an increase in the hydrogen dissociation pressure, up to Casub(0.3)Lasub(0.7)Ni 5 . In the Casub(0.3)Lasub(0.7)Ni 5 -CaNi 5 range, the dissociation pressure decreased. The absorption capacity of CaNi 5 was dependent on the purity of the sample and increased significantly at low temperatures. The stability of La(Nisub(1-x)Cusub(x)) 5 hydrides increased linearly from LaNi 5 to LaCu 5 . These features are discussed in the light of existing models of ternary and pseudoternary hydride stability. Finally, the role of the measured change in entropy ΔS in determining the occupied interstitial sites in the hydride is outlined and discussed in relation to these systems. (Auth.)

  18. A mechanistic approach to the generation of sorption databases

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1992-01-01

    Sorption of radionuclides in the near and far fields of an underground nuclear waste repository is one of the most important processes retarding their release to the environment. In the vast majority of cases sorption data have been presented in terms of empirical parameters such as distribution coefficients and isotherm equations. A consequence of this empirical methodology is that the sorption data are only strictly valid under the experimental conditions at which they were measured. Implicit in this approach is the need to generate large amounts of data and fitting parameters necessary for an empirical description of sorption under all realistically conceivable conditions which may arise in space and time along the migration pathway to Man. An alternative approach to the problem is to try to understand, and develop model descriptions of, underlying retention mechanisms and to identify those systems parameters which essentially determine the extent of sorption. The aim of this work is to see to what extent currently existing mechanistic models, together with their associated data, can be applied to predict sorption data from laboratory experiments on natural systems. This paper describes the current status of this work which is very much in an early stage of development. An example is given whereby model predictions are compared with laboratory results for the sorption of Np at trace concentrations under oxidizing conditions on a series of minerals relevant to granite formations. 31 refs., 11 figs., 5 tabs

  19. Experimental measurements and integrated modelling studies of actinide sorption onto cement

    International Nuclear Information System (INIS)

    Sugiyama, Daisuke; Fujita, Tomonari; Baston, G.M.N.

    2003-01-01

    An Integrated Cement Sorption Model (ICSM) for actinides onto Ordinary Portland Cement (OPC) is developed. The experimental measurements using the batch sorption technique for actinides onto cement and constituent minerals, which were considered in the modelling calculations, are also described. The actinide elements studied (thorium, uranium, neptunium, plutonium and americium) were strongly sorbed onto OPC. An initial comparison of the experimental data relating the sorption values of actinides onto cement-component phases with those onto OPC is carried out. The results suggest that the Calcium Silicate Hydrate (C-S-H) phases were found to be the most likely candidates to be the dominant-sorbing phases in order to describe the sorption of a actinides onto OPC. An approach to develop the integrated cement sorption model, based on a thermodynamic surface complexation model, is described with discussions on the possible mineralogy and phase distribution of OPC. Another approach than sorption, assuming that co-precipitation on the surface of the cement phase dominates 'sorption', is proposed and discussed. A scoring system is introduced to assess the applicability of the proposed ICSMs. It is suggested that the thermodynamic sorption model is recommended for the sorption of ionic species and the surface co-precipitation model is recommended for the sorption of neutral species though the sorption model is still recommended to be used to model OPC-based systems. (author)

  20. Further developments of the RES3T sorption database

    International Nuclear Information System (INIS)

    Brendler, V.

    2002-01-01

    RES 3 T - the Rossendorf expert system for surface and sorption thermodynamics currently under development has been expanded towards the provision of comprehensive sorption data sets suitable for complex natural systems of rocks and soils. Also a statistical evaluation of the available SCM (surface complexation model) data is now implemented. Finally, a normalization of SCM parameters to a standard site density has been incorporated. (orig.)

  1. Air Force Research Laboratory Spacecraft Cryocooler Endurance Evaluation Update: FY98-99

    National Research Council Canada - National Science Library

    Tomlinson, B

    1999-01-01

    The need for long term endurance evaluation data on space cryocoolers has long been an issue due to the 10-year plus design life of this technology and the absence of any accepted accelerated testing methodology...

  2. Development of a 77K Reverse-Brayton Cryocooler with Multiple Coldheads, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — RTI will design and optimize an 80 W, 77K cryocooler based on the reverse turbo Brayton cycle (RTBC) with four identical coldheads for distributed cooling. Based on...

  3. An experimental study for the phase shift between piston and displacer in the Stirling cryocooler

    Energy Technology Data Exchange (ETDEWEB)

    Park, S. J.; Hong, Y. J.; Kim, H. B. [Korea Institute of Machinery and Materials, Taejon (Korea, Republic of); Son, H. K.; Yu, B. K. [Wooyoung Co., Ltd., Seoul (Korea, Republic of)

    2002-07-01

    The small cryocooler is being widely applied to the areas of infrared detector, superconductor filter, satellite communication, and cryopump. The cryocooler working on the Stirling cycle are characterized by small size, lightweight, low power consumption and high reliability. For these reasons, FPFD (Free Piston Free Displacer) Stirling cryocooler is widely used not only tactical infrared imaging camera but also medical diagnostic apparatus. In this study, Stirling cryocooler actuated by the dual linear motor is designed and manufactured. And, displacement of the piston is measured by LVDTs (Linear Variable Differential Transformers), displacement of the displacer is measured by laser optic method, and phase shift between piston and displacer is discussed. Finally, when the phase shift between displacements of the piston and displacer is 45 .deg., operating frequency is optimum and is decided by resonant frequency of the expander, mass and cross section area of the displacer and constant by friction and flow resistance.

  4. An experimental study for the phase shift between piston and displacer in the Stirling cryocooler

    International Nuclear Information System (INIS)

    Park, S. J.; Hong, Y. J.; Kim, H. B.; Son, H. K.; Yu, B. K.

    2002-01-01

    The small cryocooler is being widely applied to the areas of infrared detector, superconductor filter, satellite communication, and cryopump. The cryocooler working on the Stirling cycle are characterized by small size, lightweight, low power consumption and high reliability. For these reasons, FPFD (Free Piston Free Displacer) Stirling cryocooler is widely used not only tactical infrared imaging camera but also medical diagnostic apparatus. In this study, Stirling cryocooler actuated by the dual linear motor is designed and manufactured. And, displacement of the piston is measured by LVDTs (Linear Variable Differential Transformers), displacement of the displacer is measured by laser optic method, and phase shift between piston and displacer is discussed. Finally, when the phase shift between displacements of the piston and displacer is 45 .deg., operating frequency is optimum and is decided by resonant frequency of the expander, mass and cross section area of the displacer and constant by friction and flow resistance

  5. Influence of milling parameters on the sorption properties of the LiH–MgB{sub 2} system doped with TiCl{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Busch, Nina; Jepsen, Julian; Pistidda, Claudio [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Puszkiel, Julián A. [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Combatientes de Malvinas 3150, 1427 Buenos Aires (Argentina); Karimi, Fahim [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Milanese, Chiara [Pavia H_2 Lab, Department of Chemistry, Physical Chemistry Division, University of Pavia, Viale Taramelli 16, I-27100 Pavia (Italy); Tolkiehn, Martin [SRXPD Beamline HASYLAB, Deutsches-Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Chaudhary, Anna-Lisa, E-mail: anna-lisa.chaudhary@hzg.de [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Klassen, Thomas; Dornheim, Martin [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany)

    2015-10-05

    Highlights: • The LiH–MgB{sub 2} system was doped with TiCl{sub 3} and milling conditions varied. • A heuristic model was used to estimate energy transfer from milling conditions. • Milling parameters were correlated with the energy transfer calculation. • 20 kJ g{sup −1} of energy transfer correlates to the optimum conditions for the system. - Abstract: Hydrogen sorption properties of the LiH–MgB{sub 2} system doped with TiCl{sub 3} were investigated with respect to milling conditions (milling times, ball to powder (BTP) ratios, rotation velocities and degrees of filling) to form the reactive hydride composite (RHC) LiBH{sub 4}–MgH{sub 2}. A heuristic model was applied to approximate the energy transfer from the mill to the powders. These results were linked to experimentally obtained quantities such as crystallite size, specific surface area (SSA) and homogeneity of the samples, using X-ray diffraction (XRD), the Brunauer–Emmett–Teller (BET) method and scanning electron microscopy (SEM), respectively. The results show that at approximately 20 kJ g{sup −1} there are no further benefits to the system with an increase in energy transfer. This optimum energy transfer value indicates that a plateau was reached for MgB{sub 2} crystallite size therefore the there was also no improvement of reaction kinetics due to no change in crystallite size. Therefore, this study shows that an optimum energy transfer value was reached for the LiH–MgB{sub 2} system doped with TiCl{sub 3}.

  6. Implementation of sorption hysteresis in multi-Fickian moisture transport

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Svensson, Staffan

    2007-01-01

    In the cellular structure of wood, bound-water diffusion and water-vapor diffusion interact via sorption in a complex moisture-transportation system. At low relative humidities, moisture transport may be modeled by a Fickian diffusion equation with a good approximation. At higher relative......-35% in moisture content. Hence, for a precise moisture content computation, sorption hysteresis must be taken into account. The present paper explains the relation between sorption hysteresis and multi-Fickian moisture transport, and clarifies how models for the two phenomena are coupled. To illustrate...

  7. Heavy metal sorption by microalgae

    International Nuclear Information System (INIS)

    Sandau, E.; Sandau, P.; Pulz, O.

    1996-01-01

    Viable microalgae are known to be able to accumulate heavy metals (bioaccumulation). Against a background of the increasing environmental risks caused by heavy metals, the microalgae Chlorella vulgaris and Spirulina platensis and their potential for the biological removal of heavy metals from aqueous solutions were taken as an example for investigation. Small-scale cultivation tests (50 l) with Cd-resistant cells of Chlorella vulgaris have shown that approx. 40% of the added 10 mg Cd/l was removed from the solution within seven days. At this heavy metal concentration sensitive cells died. Non-viable microalgae are able to eliminate heavy metal ions in a short time by biosorption in uncomplicated systems, without any toxicity problems. Compared with original biomasses, the sorption capacity of microalgal by-products changes only insignificantly. Their low price makes them economical. (orig.)

  8. Competitive sorption between glyphosphate and inorganic phosphate on clay minerals and low organic matter soils

    International Nuclear Information System (INIS)

    Dion, H.M.; Hill, H.H.Jr.; Washington State Univ., Pullmann, WA; Harsh, J.B.; Washington State Univ., Pullmann, WA

    2001-01-01

    Inorganic phosphate may influence the adsorption of glyphosate to soil surface sites. It has been postulated that glyphosphate sorption is dominated by the phosphoric acid moiety, therefore, inorganic phosphate could compete with glyphosate for surface sorption sites. Sorption of glyphosate is examined in low organic carbon systems where clay minerals dominate the available adsorption sites using 32 P-labeled phosphate and 14 C-labeled glyphosate to track sorption. Glyphosate sorption was found to be strongly dependent on phosphate additions. Isotherms were generally of the L type, which is consistent with a limited number of surface sites. Most sorption on whole soils could be accounted for by sorption observed on model clays of the same mineral type as found in the soils. (author)

  9. Organomineral Interactions and Herbicide Sorption in Brazilian Tropical and Subtropical Oxisols under No-Tillage.

    Science.gov (United States)

    Bonfleur, Eloana J; Kookana, Rai S; Tornisielo, Valdemar L; Regitano, Jussara B

    2016-05-25

    We evaluated the effects of the soil organic matter (SOM) composition, distribution between soil aggregates size, and their interactions with the mineral phase on herbicide sorption (alachlor, bentazon, and imazethapyr) in tropical and subtropical Oxisols under no-till systems (NT). Using soil physical fractionation approach, sorption experiments were performed on whole soils and their aggregates. SOM chemistry was assessed by CP/MAS (13)C NMR. The lower sorption observed in tropical soils was attributed to the greater blockage of SOM sorption sites than in subtropical soils. When these sites were exposed upon physical fractionation, sorption of the three herbicides in tropical soils increased, especially for imazethapyr. High amounts of poorly crystallized sesquioxides in these soils may have contributed to masking of sorption sites, indicating that organomineral interactions may lead to blockage of sorption sites on SOM in tropical soils.

  10. Sorption properties and reversibility of Ti(IV) and Nb(V)-fluoride doped-Ca(BH4)2-MgH2 system

    International Nuclear Information System (INIS)

    Bonatto Minella, Christian; Garroni, Sebastiano; Pistidda, Claudio; Baró, Maria Dolors; Gutfleisch, Oliver; Klassen, Thomas; Dornheim, Martin

    2015-01-01

    Highlights: • Faster desorption reaction for doped materials vs. the pure composite system. • Kinetic improvement concerning re-hydrogenation reaction showed by the addition of NbF 5 . • Full characterization of the de-hydrogenation reaction pathway by means of both SR-PXD and 11 B{ 1 H} MAS-NMR. • Study of the evolution of the chemical state of the additives upon both milling and sorption reactions. - Abstract: In the last decade, alkaline and alkaline earth metal tetrahydroborates have been the focuses of the research due to their high gravimetric and volumetric hydrogen densities. Among them, Ca(BH 4 ) 2 and the Ca(BH 4 ) 2 + MgH 2 reactive hydride composites (RHC), were calculated to have the ideal thermodynamic properties which fall within the optimal range for mobile applications. In this study, the addition of NbF 5 or TiF 4 to the Ca(BH 4 ) 2 + MgH 2 reactive hydride composite system was attempted aiming to obtain a full reversible system with the simultaneous suppression of CaB 12 H 12 . Structural characterization of the specimens was performed by means of in-situ Synchrotron Radiation Powder X-ray diffraction (SR-PXD) and 11 B{ 1 H} Solid State Magic Angle Spinning-Nuclear Magnetic Resonance (MAS-NMR). The evolution of the chemical state of the Nb- and Ti-based additives was monitored by X-ray Absorption Near Edge Structure (XANES). The addition of NbF 5 or TiF 4 to the Ca(BH 4 ) 2 + MgH 2 system have not suppressed completely the formation of CaB 12 H 12 and only a slight improvement concerning the reversible reaction was displayed just in the case of Nb-doped composite material

  11. Development of Pulse Tube Cryocoolers at SITP for Space Application

    Science.gov (United States)

    Zhang, Ankuo; Wu, Yinong; Liu, Shaoshuai; Yu, Huiqin; Yang, Baoyu

    2018-05-01

    Over the last 10 years, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, has developed very high-efficiency pulse tube cryocoolers (PTCs) for aerospace applications. These PTCs can provide cooling power from milliwatt scale to tens of watts over a range of temperatures from 30 to 170 K and can be used to cool a variety of detectors in space applications (such as quantum interference devices, radiometers and ocean color sensors) that must operate at a specific cryogenic temperature to increase the signal-to-noise ratio, sensitivity and optical resolution. This paper reviews the development of single-stage PTCs over a range of weights from 1.6 to 12 kg that offer cooling powers at the cold temperature range from 40 to 170 K. In addition, a two-stage 30 K-PTC is under development.

  12. Development of New Cryocooler Regenerator Materials-Ductile Intermetallic Compounds

    International Nuclear Information System (INIS)

    Gschneidner, K.A.; Pecharsky, A.O.; Pecharsky, V.K.

    2004-01-01

    The volumetric heat capacities of a number of binary and ternary Er- and Tm-based intermetallic compounds, which exhibited substantial ductilities, were measured from ∼3 to ∼350 K. They have the RM stoichiometry (where R = Er or Tm, and M is a main group or transition metal) and crystallize in the CsCl-type structure. The heat capacities of the Tm-based compounds are in general larger than the corresponding Er-based materials. Many of them have heat capacities which are significantly larger than those of the low temperature ( 2 , Er 3 Ni and ErNi. Utilization of the new materials as regenerators in the various cryocoolers should improve the performance of these refrigeration units for cooling below 15 K

  13. Thermal Analysis of Cryocooler-Cooled Bi2223 Pulsed Coil

    International Nuclear Information System (INIS)

    Miyazaki, H; Chigusa, S; Tanaka, I; Iwakuma, M; Funaki, K; Hayashi, H; Tomioka, A

    2006-01-01

    We fabricated a cryocooler-cooled Bi2223 superconducting pulsed coil and experimentally studied thermal runaway in dc or ac operation. We carried out numerical simulation of thermal properties of the coil in order to explain thermal runaway of the coil. Firstly, we analyzed the total heat generation of flux-flow loss and ac loss inside the winding from the experimental results of the external field losses and the E-J characteristics for the Bi2223 strands. Secondly, we numerically simulated the thermal properties by using 2- dimensional heat conduction equation with axial symmetry. The numerical simulation shows the relation between the initiation of thermal runaway and the temperature distribution with highly concentrated heat source in the winding. We have a semi-quantitative agreement between the numerical results and the experimental ones for the condition of the thermal runaway

  14. The effect of low temperature cryocoolers on the development of low temperature superconducting magnets

    International Nuclear Information System (INIS)

    Green, Michael A.

    2000-01-01

    The commercial development of reliable 4 K cryocoolers improves the future prospects for magnets made from low temperature superconductors (LTS). The hope of the developers of high temperature superconductors (HTS) has been to replace liquid helium cooled LTS magnets with HTS magnets that operate at or near liquid nitrogen temperature. There has been limited success in this endeavor, but continued problems with HTS conductors have greatly slowed progress toward this goal. The development of cryocoolers that reliably operate below 4 K will allow magnets made from LTS conductor to remain very competitive for many years to come. A key enabling technology for the use of low temperature cryocoolers on LTS magnets has been the development of HTS leads. This report describes the characteristics of LTS magnets that can be successfully melded to low-temperature cryocoolers. This report will also show when it is not appropriate to consider the use of low-temperature cryocoolers to cool magnets made with LTS conductor. A couple of specific examples of LTS magnets where cryocoolers can be used are given

  15. The Ricor K508 cryocooler operational experience on Mars

    International Nuclear Information System (INIS)

    Johnson, Dean L.; Lysek, Mark J.; Morookian, John Michael

    2014-01-01

    The Mars Science Laboratory (Curiosity) landed successfully on Mars on August 5, 2012, eight months after launch. The chosen landing site of Gale Crater, located at 4.5 degrees south latitude, 137.4 degrees east longitude, has provided a much more benign environment than was originally planned for during the critical design and integration phases of the MSL Project when all possible landing sites were still being considered. The expected near-surface atmospheric temperatures at the Gale Crater landing site during Curiosity's primary mission (1 Martian year or 687 Earth days) are from −90°C to 0°C. However, enclosed within Curiosity's thermal control fluid loops the Chemistry and Mineralogy (CheMin) instrument is maintained at approximately +20°C. The CheMin instrument uses X-ray diffraction spectroscopy to make precise measurements of mineral constituents of Mars rocks and soil. The instrument incorporated the commercially available Ricor K508 Stirling cycle cryocooler to cool the CCD detector. After several months of brushing itself off, stretching and testing out its subsystems, Curiosity began the exploration of the Mars surface in October 2012. The CheMin instrument on the Mars Science Laboratory (MSL) received its first soil sample from Curiosity on October 24, and successfully analyzed its first soil sample. After a brief review of the rigorous Ricor K508 cooler qualification tests and life tests based on the original MSL environmental requirements this paper presents final pre-launch instrument integration and testing results, and details the operational data of the CheMin cryocooler, providing a snapshot of the resulting CheMin instrument analytical data

  16. The Ricor K508 cryocooler operational experience on Mars

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Dean L.; Lysek, Mark J.; Morookian, John Michael [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2014-01-29

    The Mars Science Laboratory (Curiosity) landed successfully on Mars on August 5, 2012, eight months after launch. The chosen landing site of Gale Crater, located at 4.5 degrees south latitude, 137.4 degrees east longitude, has provided a much more benign environment than was originally planned for during the critical design and integration phases of the MSL Project when all possible landing sites were still being considered. The expected near-surface atmospheric temperatures at the Gale Crater landing site during Curiosity's primary mission (1 Martian year or 687 Earth days) are from −90°C to 0°C. However, enclosed within Curiosity's thermal control fluid loops the Chemistry and Mineralogy (CheMin) instrument is maintained at approximately +20°C. The CheMin instrument uses X-ray diffraction spectroscopy to make precise measurements of mineral constituents of Mars rocks and soil. The instrument incorporated the commercially available Ricor K508 Stirling cycle cryocooler to cool the CCD detector. After several months of brushing itself off, stretching and testing out its subsystems, Curiosity began the exploration of the Mars surface in October 2012. The CheMin instrument on the Mars Science Laboratory (MSL) received its first soil sample from Curiosity on October 24, and successfully analyzed its first soil sample. After a brief review of the rigorous Ricor K508 cooler qualification tests and life tests based on the original MSL environmental requirements this paper presents final pre-launch instrument integration and testing results, and details the operational data of the CheMin cryocooler, providing a snapshot of the resulting CheMin instrument analytical data.

  17. Vibration-free stirling cryocooler for high definition microscopy

    Science.gov (United States)

    Riabzev, S. V.; Veprik, A. M.; Vilenchik, H. S.; Pundak, N.; Castiel, E.

    2009-12-01

    The normal operation of high definition Scanning Electronic and Helium Ion microscope tools often relies on maintaining particular components at cryogenic temperatures. This has traditionally been accomplished by using liquid coolants such as liquid Nitrogen. This inherently limits the useful temperature range to above 77 K, produces various operational hazards and typically involves elevated ownership costs, inconvenient logistics and maintenance. Mechanical coolers, over-performing the above traditional method and capable of delivering required (even below 77 K) cooling to the above cooled components, have been well-known elsewhere for many years, but their typical drawbacks, such as high purchasing cost, cooler size, low reliability and high power consumption have so far prevented their wide-spreading. Additional critical drawback is inevitable degradation of imagery performance originated from the wideband vibration export as typical for the operation of the mechanical cooler incorporating numerous movable components. Recent advances in the development of reliable, compact, reasonably priced and dynamically quiet linear cryogenic coolers gave rise to so-called "dry cooling" technologies aimed at eventually replacing the traditional use of outdated liquid Nitrogen cooling facilities. Although much improved these newer cryogenic coolers still produce relatively high vibration export which makes them incompatible with modern high definition microscopy tools. This has motivated further research activity towards developing a vibration free closed-cycle mechanical cryocooler. The authors have successfully adapted the standard low vibration Stirling cryogenic refrigerator (Ricor model K535-LV) delivering 5 W@40 K heat lift for use in vibration-sensitive high definition microscopy. This has been achieved by using passive mechanical counterbalancing of the main portion of the low frequency vibration export in combination with an active feed-forward multi

  18. Study of the radium sorption/desorption on goethite

    International Nuclear Information System (INIS)

    Bassot, S.; Stammose, D.; Mallet, C.; Lefebvre, C.; Ferreux, J.-M.

    2000-01-01

    The oxi-hydroxides, present at trace level in uranium mill tailings, are responsible of about 70% of the 226 radium sorption, half being fixed on crystallized forms. This radionuclide (half time=1622y), present at high level (50 to 100kBq.kg -1 ), can be released in groundwater, involving a possible contamination of the food chain (actual concentration limit=0.37Bq.1 -1 ). So, it is very important to point out the mechanisms of the radium sorption/desorption on crystallized oxi-hydroxides as a function of chemical conditions of the system. The radium sorption on synthetic goethite α-FeOOH has been studied as a function of contact time, initial radium activity, pH, sodium and calcium concentrations. The results show that, after one hour of contact time (necessary to reach equilibrium), the radium sorption increases widely in a pH range 6-7. The increase of Na + concentration is without influence on the radium sorption, indicating the low interactions between sodium and surface sites. At the opposite, the presence of calcium in solution decreases widely the radium sorption, that indicates a competition between calcium and radium for the same kind of sorption sites of the oxi-hydroxide surface. The percentage of radium desorbed increases widely with time, from 1 to 120h and becomes constant at a time higher than 120h. This long equilibrium time for desorption in comparison with sorption one can be explain by a local evolution of the sorption sites of the solid, which become less accessible for the solution in contact. (author)

  19. Numerical simulation of tubes-in-tube heat exchanger in a mixed refrigerant Joule-Thomson cryocooler

    Science.gov (United States)

    Damle, R. M.; Ardhapurkar, P. M.; Atrey, M. D.

    2017-02-01

    Mixed refrigerant Joule-Thomson (MRJT) cryocoolers can produce cryogenic temperatures with high efficiency and low operating pressures. As compared to the high system pressures of around 150-200 bar with nitrogen, the operational pressures with non-azeotropic mixtures (e.g., nitrogen-hydrocarbons) come down to 10-25 bar. With mixtures, the heat transfer in the recuperative heat exchanger takes place in the two-phase region. The simultaneous boiling and condensation of the cold and hot gas streams lead to higher heat transfer coefficients as compared to single phase heat exchange. The two-phase heat transfer in the recuperative heat exchanger drastically affects the performance of a MRJT cryocooler. In this work, a previously reported numerical model for a simple tube-in-tube heat exchanger is extended to a multi tubes-in-tube heat exchanger with a transient formulation. Additionally, the J-T expansion process is also considered to simulate the cooling process of the heat exchanger from ambient temperature conditions. A tubes-in-tube heat exchanger offers more heat transfer area per unit volume resulting in a compact design. Also, the division of flow in multiple tubes reduces the pressure drop in the heat exchanger. Simulations with different mixtures of nitrogen-hydrocarbons are carried out and the numerical results are compared with the experimental data.

  20. Modelling of a stirling cryocooler regenerator under steady and steady - periodic flow conditions using a correlation based method

    Science.gov (United States)

    Kishor Kumar, V. V.; Kuzhiveli, B. T.

    2017-12-01

    The performance of a Stirling cryocooler depends on the thermal and hydrodynamic properties of the regenerator in the system. CFD modelling is the best technique to design and predict the performance of a Stirling cooler. The accuracy of the simulation results depend on the hydrodynamic and thermal transport parameters used as the closure relations for the volume averaged governing equations. A methodology has been developed to quantify the viscous and inertial resistance terms required for modelling the regenerator as a porous medium in Fluent. Using these terms, the steady and steady - periodic flow of helium through regenerator was modelled and simulated. Comparison of the predicted and experimental pressure drop reveals the good predictive power of the correlation based method. For oscillatory flow, the simulation could predict the exit pressure amplitude and the phase difference accurately. Therefore the method was extended to obtain the Darcy permeability and Forchheimer’s inertial coefficient of other wire mesh matrices applicable to Stirling coolers. Simulation of regenerator using these parameters will help to better understand the thermal and hydrodynamic interactions between working fluid and the regenerator material, and pave the way to contrive high performance, ultra-compact free displacers used in miniature Stirling cryocoolers in the future.

  1. Uranium sorption on tezontle volcanic rock

    International Nuclear Information System (INIS)

    Lopez M, B. E.; Duran B, J. M.; Iturbe G, J. L.; Olguin G, M. T.

    2009-01-01

    It is described a study that demonstrates that hexavalent uranium ions were sorbed by the naturally occurring mineral using a batch technique. This mineral is found in abundant quantities in Mexico. Our study focused on the separation of U Vi from synthetic aqueous systems of both H 2 O-UO 2 (NO 3 ) 2 .6H 2 O (acid) and H 2 O-Na 4 [UO 2 (CO 3 ) 3 ] (basic). The chemical speciation was performed by using high voltage electrophoresis, and the uranium content was determined by UV-Vis spectroscopy. The quantified U(Vi) sorption by tezontle from acidic and basic systems was 2.72 and 1.68 μmol/g, respectively, and the sorption behavior is discussed considering the surface charge of the tezontle at different ph values based on the point of zero charge characteristic of this material. (Author)

  2. Sorption of samarium in iron (II) and (III) phosphates in aqueous systems; Sorcion de samario en fosfatos de hierro (II) y (III) en sistemas acuosos

    Energy Technology Data Exchange (ETDEWEB)

    Diaz F, J C

    2006-07-01

    The radioactive residues that are stored in the radioactive confinements its need to stay isolated of the environment while the radioactivity levels be noxious. An important mechanism by which the radioactive residues can to reach the environment, it is the migration of these through the underground water. That it makes necessary the investigation of reactive materials that interacting with those radionuclides and that its are able to remove them from the watery resources. The synthesis and characterization of materials that can be useful in Environmental Chemistry are very important because its characteristics are exposed and its behavior in chemical phenomena as the sorption watery medium is necessary to use it in the environmental protection. In this work it was carried out the sorption study of the samarium III ion in the iron (II) and (III) phosphate; obtaining the sorption isotherms in function of pH, of the phosphate mass and of the concentration of the samarium ion using UV-visible spectroscopy to determine the removal percentage. The developed experiments show that as much the ferrous phosphate as the ferric phosphate present a great affinity by the samarium III, for what it use like reactive material in contention walls can be very viable because it sorption capacity has overcome 90% to pH values similar to those of the underground and also mentioning that the form to obtain these materials is very economic and simple. (Author)

  3. Batch experiments for assessing the sorption/desorption characteristics of 152Eu in systems of loose sediments and water containing humic acids

    International Nuclear Information System (INIS)

    Klotz, D.

    2001-01-01

    The 152 Eu distribution coefficients of the sorption and desorption of non-binding loose sediments of different grain sizes are investigated using a groundwater of tertiary lignite from Northern Germany which contains high concentrations of humic acids. The batch experiments were carried out with a ratio of 2.5cm 3 /g of solution volume to sediment mass, without mixing [de

  4. Thermodynamic parameters and sorption of U(VI) on ACSD

    International Nuclear Information System (INIS)

    Donat, R.; Cilgi, G.K.; Cetisli, H.; Aytas, S.

    2009-01-01

    This paper discusses the sorption properties for U(VI) by alginate coated CaSO 4 x 2H 2 O sepiolite and calcined diatomite earth (Kieselguhr) (ACSD). The removal of U(VI) from aqueous solution by sorption onto ACSF in a single component system with various contact times, pH, temperatures, and initial concentrations of U(VI) was investigated. The sorption patterns of uranium on the composite adsorbent followed the Langmuir, Freundlich and Dubinin-Radushkhevic (D-R) isotherms. The Freundlich, Langmuir, and D-R models have been applied and the data correlated well with Freundlich model and that the sorption was physical in nature (sorption energy, E a = 17.05 kJ/mol). The thermodynamic parameters such as variation of enthalpy ΔH, variation of entropy ΔS and variation of Gibbs free energy ΔG were calculated from the slope and intercept of lnK 0 vs. 1/T plots. Thermodynamic parameters (ΔH ads = 31.83 kJ/mol, ΔS ads = 167 J/mol x K, ΔGdeg ads (293.15 K) = -17.94 kJ/mol) showed the endothermic heat of sorption and the feasibility of the process. The thermodynamics of U(VI) ion/ACSD system indicates the spontaneous and endothermic nature of the process. It was noted that an increase in temperature resulted in a higher uranium loading per unit weight of the adsorbent. (author)

  5. Development of a heavy metal sorption system through the P=S functionalization of coconut (Cocos nucifera) fibers.

    Science.gov (United States)

    de Sousa, Dayane Almeida; de Oliveira, Elisabeth; da Costa Nogueira, Márcio; Espósito, Breno Pannia

    2010-01-01

    Lignocellulosic residues are interesting materials for the production of heavy metal adsorbents for aquatic systems. Whole fibers taken from coconut (Cocos nucifera) husks were functionalized with the thiophosphoryl (P=S) group by means of the direct reaction with Cl(3)PS, (CH(3)O)(2)ClP=S or (CH(3)CH(2)O)(2)ClP=S in order to obtain an adsorptive system for 'soft' metal ions, particularly Cd(2+). These functionalized fibers (FFs) were characterized by means of elemental analysis, infrared spectroscopy, thermal analysis and acid-base titration. Adsorption isotherms for Cd(2+) fitted the Langmuir model, with binding capacities of 0.2-5 m mol g(-1) of FF at 25 degrees C.

  6. Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies

    Science.gov (United States)

    Evans, K.; Ferris, F.

    2009-05-01

    prediction of fluoride removal in a wide variety of groundwater systems. Sorption isotherms and affinity constants show the use of BIOS to be a promising technique for the remediation of fluoride in groundwater.

  7. Sorption analyses in materials science: selected oxides

    International Nuclear Information System (INIS)

    Fuller, E.L. Jr.; Condon, J.B.; Eager, M.H.; Jones, L.L.

    1981-01-01

    Physical adsorption studies have been shown to be extremely valuable in studying the chemistry and structure of dispersed materials. Many processes rely on the access to the large amount of surface made available by the high degree of dispersion. Conversely, there are many applications where consolidation of the dispersed solids is required. Several systems (silica gel, alumina catalysts, mineralogic alumino-silicates, and yttrium oxide plasters) have been studied to show the type and amount of chemical and structural information that can be obtained. Some review of current theories is given and additional concepts are developed based on statistical and thermodynamic arguments. The results are applied to sorption data to show that detailed sorption analyses are extremely useful and can provide valuable information that is difficult to obtain by any other means. Considerable emphasis has been placed on data analyses and interpretation of a nonclassical nature to show the potential of such studies that is often not recognized nor utilized

  8. Sorption properties of carbon nanostructures

    International Nuclear Information System (INIS)

    Eletskii, Aleksandr V

    2004-01-01

    The current status of research in sorption properties of carbon nanotubes (CNTs) is reviewed. The structural peculiarities of CNTs, determining their sorption characteristics, are considered. The mechanisms of sorption of gaseous and condensed substances by such structures are analyzed. Special attention is paid to the problem of using CNTs for storing hydrogen and other gaseous substances. Methods for filling CNTs with liquid materials, based on capillary phenomena and wetting the graphite surface of the CNT with liquids of various nature, are considered. Properties of 'peapods' formed as a result of filling single-walled CNTs with fullerene molecules are reviewed. Also considered are perspectives on the applied usage of the sorption properties of CNTs in electrochemical and fuel cells, and material storage devices, as well as for producing superminiature metallic conductors. (reviews of topical problems)

  9. Hydrodynamic parameters of micro porous media for steady and oscillatory flow: Application to cryocooler regenerators

    Science.gov (United States)

    Cha, Jeesung Jeff

    Pulse Tube Cryocoolers (PTC) are a class of rugged and high-endurance refrigeration systems that operate without a moving part at their low temperature ends, and are capable of easily reaching 120°K. These devices can also be configured in multiple stages to reach temperatures below 10 °K. PTCs are particularly suitable for applications in space, missile guiding systems, cryosurgery, medicine preservation, superconducting electronics, magnetic resonance imaging, weather observation, and liquefaction of nitrogen. Although various designs of PTCs have been in use for a few decades, they represent a dynamic and developmental field. PTCs ruggedness comes at the price of relatively low efficiency, however, and thus far they have been primarily used in high-end applications. They have the potential of extensive use in consumer products, however, should sufficiently higher efficiencies be achieved. Intense research competition is underway worldwide, and newer designs are continuously introduced. Some of the fundamental processes that are responsible for their performance are at best not fully understood, however, and consequently systematic modeling of PTC systems is difficult. Among the challenges facing the PTC research community, besides improvement in terms of system efficiency, is the possible miniaturization (total fluid volume of few cubic centimeters (cc)) of these systems. The operating characteristics of a PTC are significantly different from the conventional refrigeration cycles. A PTC implements the theory of oscillatory compression and expansion of the gas within a closed volume to achieve desired refrigeration. Regenerators and pulse tubes are often viewed as the two most complex and essential components in cryocoolers. An important deficiency with respect to the state of art models dealing with PTCs is the essentially total lack of understanding about the directional hydrodynamic and thermal transport parameters associated with periodic flow in

  10. Sorption properties and reversibility of Ti(IV) and Nb(V)-fluoride doped-Ca(BH{sub 4}){sub 2}-MgH{sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    Bonatto Minella, Christian, E-mail: christian.minella@kit.edu [Institute for Metallic Materials, IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Technische Universität Dresden, D-01062 Dresden (Germany); Garroni, Sebastiano [Dipartimento di Chimica e Farmacia, Universitá di Sassari and INSTM, Via Vienna 2, I-07100 Sassari (Italy); Pistidda, Claudio [Institute of Materials Research, Materials Technology, Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH, Max Planck Str. 1, D-21502 Geesthacht (Germany); Baró, Maria Dolors [Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); Gutfleisch, Oliver [Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt (Germany); Klassen, Thomas; Dornheim, Martin [Institute of Materials Research, Materials Technology, Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH, Max Planck Str. 1, D-21502 Geesthacht (Germany)

    2015-02-15

    Highlights: • Faster desorption reaction for doped materials vs. the pure composite system. • Kinetic improvement concerning re-hydrogenation reaction showed by the addition of NbF{sub 5}. • Full characterization of the de-hydrogenation reaction pathway by means of both SR-PXD and {sup 11}B{"1H} MAS-NMR. • Study of the evolution of the chemical state of the additives upon both milling and sorption reactions. - Abstract: In the last decade, alkaline and alkaline earth metal tetrahydroborates have been the focuses of the research due to their high gravimetric and volumetric hydrogen densities. Among them, Ca(BH{sub 4}){sub 2} and the Ca(BH{sub 4}){sub 2} + MgH{sub 2} reactive hydride composites (RHC), were calculated to have the ideal thermodynamic properties which fall within the optimal range for mobile applications. In this study, the addition of NbF{sub 5} or TiF{sub 4} to the Ca(BH{sub 4}){sub 2} + MgH{sub 2} reactive hydride composite system was attempted aiming to obtain a full reversible system with the simultaneous suppression of CaB{sub 12}H{sub 12}. Structural characterization of the specimens was performed by means of in-situ Synchrotron Radiation Powder X-ray diffraction (SR-PXD) and {sup 11}B{"1H} Solid State Magic Angle Spinning-Nuclear Magnetic Resonance (MAS-NMR). The evolution of the chemical state of the Nb- and Ti-based additives was monitored by X-ray Absorption Near Edge Structure (XANES). The addition of NbF{sub 5} or TiF{sub 4} to the Ca(BH{sub 4}){sub 2} + MgH{sub 2} system have not suppressed completely the formation of CaB{sub 12}H{sub 12} and only a slight improvement concerning the reversible reaction was displayed just in the case of Nb-doped composite material.

  11. Sorption mechanism of solvent vapors to coals; Sekitan eno yobai joki no shuchaku kiko no kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, K.; Takanohashi, T.; Iino, M. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

    1996-10-28

    With an objective to clarify the interactions between micropore structure of coal and solvent reagents, a sorption experiment was carried out under solvent saturated vapor pressure. Low-volatile bituminous coal, Pocahontas No. 3 coal, has the aromatic ring structure developed, and makes solvent more difficult to diffuse into coal, hence sorption amount is small. Methanol has permeated since its polarity is high. High-volatile bituminous coal, Illinois No. 6 coal, makes solvent penetrate easily, and the sorption amount was large with both of aromatic and polar solvents. Since brown coal, Beulah Zap coal, contains a large amount of oxygen, and hydrogen bonding is predominant, sorption amount of cyclohexane and benzene having no polarity is small. Methanol diffuses while releasing hydrogen bond due to its polarity, and its sorption amount is large. A double sorption model is available, which expresses the whole sorption amount as a sum of physical sorption amount and amount of permeation into coal. This model was applied when it explained successfully the sorption behavior of the solvents relative to coals, excepting some of the systems. However, also observed were such abnormal behavior as sorption impediment due to interactions between coal surface and solvents, and permeation impediment due to hydroxyl groups inside the coals. 1 ref., 10 figs., 2 tabs.

  12. Sorption-desorption of antimony species onto calcined hydrotalcite: Surface structure and control of competitive anions.

    Science.gov (United States)

    Constantino, Leonel Vinicius; Quirino, Juliana Nunes; Abrão, Taufik; Parreira, Paulo Sérgio; Urbano, Alexandre; Santos, Maria Josefa

    2018-02-15

    Calcined hydrotalcite can be applied to remove anionic contaminants from aqueous systems such as antimony species due to its great anion exchange capacity and high surface area. Hence, this study evaluated antimonite and antimonate sorption-desorption processes onto calcined hydrotalcite in the presence of nitrate, sulfate and phosphate. Sorption and desorption experiments of antimonite and antimonate were carried out in batch equilibrium and the post-sorption solids were analyzed by X-ray fluorescence (EDXRF). Sorption data were better fitted by dual-mode Langmuir-Freundlich model (R 2 >0.99) and desorption data by Langmuir model. High maximum sorption capacities were found for the calcined hydrotalcite, ranging from 617 to 790meqkg -1 . The competing anions strongly affected the antimony sorption. EDXRF analysis and mathematical modelling showed that sulfate and phosphate presented higher effect on antimonite and antimonate sorption, respectively. High values for sorption efficiency (SE=99%) and sorption capacity were attributed to the sorbent small particles and the large surface area. Positive hysteresis indexes and low mobilization factors (MF>3%) suggest very low desorption capacity to antimony species from LDH. These calcined hydrotalcite characteristics are desirable for sorption of antimony species from aqueous solutions. Copyright © 2017. Published by Elsevier B.V.

  13. 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)

  14. Sorption of water vapor in partially hydrolyzed poly(vinyl acetate)

    International Nuclear Information System (INIS)

    Spencer, H.G.; Honeycutt, S.C.

    1973-01-01

    The sorption kinetics of H 2 O and D 2 O in copolymers of partially hydrolyzed poly(vinyl acetate) were studied and compared with the sorption kinetics of vinyl acetate--vinyl alcohol copolymers, and poly(vinyl alcohol). The special measurement problems presented by transient-state sorption studies in water vapor--polymer systems and their effects on the results are discussed

  15. Analysis of sorption into single ODS-silica gel microparticles in acetonitrile-water.

    Science.gov (United States)

    Nakatani, Kiyoharu; Kakizaki, Hiroshi

    2003-08-01

    Intraparticle mass transfer processes of Phenol Blue (PB) in single octadecylsilyl (ODS)-silica gel microparticles in acetonitrile-water were analyzed by microcapillary manipulation and microabsorption methods. An absorption maximum of PB, the sorption isotherm parameters, and the sorption rate in the microparticle system were highly dependent on the percentage of acetonitrile in solution. The results are discussed in terms of the microscopic polarity surrounding PB in the ODS phase and the relationship between the isotherm parameters and the sorption rate.

  16. A space-qualified experiment integrating HTS digital circuits and small cryocoolers

    International Nuclear Information System (INIS)

    Silver, A.; Akerling, G.; Auten, R.

    1996-01-01

    High temperature superconductors (HTS) promise to achieve electrical performance superior to that of conventional electronics. For application in space systems, HTS systems must simultaneously achieve lower power, weight, and volume than conventional electronics, and meet stringent space qualification and reliability requirements. Most effort to date has focused on passive RF/microwave applications. However, incorporation of active microwave components such as amplifiers, mixers, and phase shifters, and on-board high data rate digital signal processing is limited by the power and weight of their spacecraft electronic and support modules. Absence of data on active HTS components will prevent their utilization in space. To validate the feasibility in space of HTS circuits and components based on Josephson junctions, one needs to demonstrate HTS circuits and critical supporting technologies, such as space-qualified packaging and interconnects, closed-cycle cryocooling, and interface electronics. This paper describes the packaging, performance, and space test plan of an integrated, space-qualified experimental package consisting of HTS Josephson junction circuits and all the supporting components for NRL's high temperature superconductor space experiment (HTSSE-II). Most of the technical challenges and approaches are equally applicable to passive and active RF/microwave and digital electronic components, and this experiment will provide valuable validation data

  17. PERFORMANCE ENHANCEMENT OF A MINIATURE STIRLING CRYOCOOLER WITH A MULTI MESH REGENERATOR DESIGN

    Directory of Open Access Journals (Sweden)

    KISHOR KUMAR V. V.

    2017-06-01

    Full Text Available A parametric study has been carried out using the software REGEN 3.3 to optimize the regenerator of a miniature Stirling cryocooler operating with a warm end temperature of 300 K and cold end temperature of 80 K. Regenerator designs which produce the maximum coefficient of performance (COP of the system is considered as an optimized regenerator. The length and diameter of the regenerator were fixed from the cooler system requirements. Single mesh regenerators made of 200, 250, 300, 400 and 450 Stainless Steel wire meshes were considered and the optimum phase angle and mesh size were obtained. A maximum COP of 0.1475 was obtained for 300 mesh regenerator at 70° phase angle. Then multi mesh regenerators were considered with finer mesh on the cold end and coarser mesh on the hot end. The optimum size and length of each mesh in the multi mesh regenerator and the optimum phase angle were calculated. The maximum COP of 0.156 was obtained for 200 300-400 multi mesh regenerator at 70° phase angle. The COP and net refrigeration obtained for an optimized multi mesh regenerator was found to be significantly higher than that of a single mesh regenerator. Thus a multi mesh regenerator design with a proper combination of regenerator mesh size and length can enhance the regenerator effectiveness.

  18. How to manage MTTF larger than 30,000hr on rotary cryocoolers

    Science.gov (United States)

    Cauquil, Jean-Marc; Seguineau, Cédric; Martin, Jean-Yves; Van-Acker, Sébastien; Benschop, Tonny

    2017-05-01

    The cooled IR detectors are used in a wide range of applications. Most of the time, the cryocoolers are one of the components dimensioning the lifetime of the system. Indeed, Stirling coolers are mechanical systems where wear occurs on millimetric mechanisms. The exponential law classically used in electronics for Mean Time to Failure (MTTF) calculation cannot be directly used for mechanical devices. With new applications for thermal sensor like border surveillance, an increasing reliability has become mandatory for rotary cooler. The current needs are above several tens of thousands of continuous hour of cooling. Thales Cryogenics made specific development on that topic, for both linear and rotary applications. The time needed for validating changes in processes through suited experimental design is hardly affordable by following a robust and rigorous standard scientific approach. The targeted Mean Time to Failure (MTTF) led us to adopt an innovative approach to keep development phases in line with expected time to market. This innovative approach is today widespread on all of Thales Cryogenics rotary products and results in a proven increase of MTTF for RM2, RM3 and recently RM1. This paper will then focused on the current MTTF figures measured on RM1, RM2 and RM3. After explaining the limit of a conventional approach, the paper will then describe the current method. At last, the authors will explain how these principles are taken into account for the new SWaP rotary cooler of Thales Cryogénie SAS.

  19. Radionuclides sorption in clay soils

    International Nuclear Information System (INIS)

    Siraky, G.; Lewis, C.; Hamlat, S.; Nollmann, C.E.

    1987-01-01

    The sorption behaviour of clay soils is examined through a parametric study of the distribution coefficient (Kd) for the radionuclides of interest, Cs and Sr. This work is a preliminary stage of the migration studies of these nuclides in a porous medium (ground of Ezeiza, Argentina) and the evaluation of radiologic impact of the removal of low and intermediate activity wastes in shallow trenches. The determination of Kd is performed by a static technique or batch. The phases are separated by centrifugation at 20000 g during 1 hour. The activity of supernatant solution of Cs-137 and Sr-85 is measured in a detecting system of I Na(Tl) well-type. Two types of parameters were changed: a) those related to the determination method: phase separation (centrifugation vs. centrifugation plus filtration); equilibrium period, ratio solid/liquid; b) those related to the geochemical system: pH of contact solution, carrier concentration, competitive ions, ionic strength, desorption. It was observed that the modification of parameters in the Kd-measurement does not change the order of magnitude of results. (Author)

  20. Competitive sorption of persistent organic pollutants onto microplastics in the marine environment

    International Nuclear Information System (INIS)

    Bakir, Adil; Rowland, Steven J.; Thompson, Richard C.

    2012-01-01

    Highlights: ► Organic pollutants are present as complex mixtures in the marine environment. ► The competitive sorption of phenanthrene and DDT in a bi-solute system was investigated onto PVC and PE. ► DDT outcompeted phenanthrene for sorption onto plastic. ► DDT also appeared to have a negative effect on the sorption of phenanthrene onto plastic when added at high concentration. - Abstract: Plastics are known to sorb persistent organic pollutants from seawater. However, studies to quantify sorption rates have only considered the affinity of chemicals in isolation, unlike the conditions in the environment where contaminants are present as complex mixtures. Here we examine whether phenanthrene and 4,4′-DDT, in a mixture, compete for sorption sites onto PVC with no added additives (unplasticised PVC or uPVC) and Ultra-High Molecular Weight polyethylene. Interactions were investigated by exposing particles of uPVC and UHMW PE to mixtures of 3H and 14C radiolabelled Phe and DDT. Changes in sorption capacity were modelled by applying a Freundlich binding sorption isotherms. An Extended Langmuir Model and an Interaction Factor Model were also applied to predict equilibrium concentrations of pollutants onto plastic. This study showed that in a bi-solute system, DDT exhibited no significantly different sorption behaviour than in single solute systems. However, DDT did appear to interfere with the sorption of Phe onto plastic, indicating an antagonistic effect.

  1. Operating characteristics of a single-stage Stirling cryocooler capable of providing 700 W cooling power at 77 K

    Science.gov (United States)

    Xu, Ya; Sun, Daming; Qiao, Xin; Yu, Yan S. W.; Zhang, Ning; Zhang, Jie; Cai, Yachao

    2017-04-01

    High cooling capacity Stirling cryocooler generally has hundreds to thousands watts of cooling power at liquid nitrogen temperature. It is promising in boil-off gas (BOG) recondensation and high temperature superconducting (HTS) applications. A high cooling capacity Stirling cryocooler driven by a crank-rod mechanism was developed and studied systematically. The pressure and frequency characteristics of the cryocooler, the heat rejection from the ambient heat exchanger, and the cooling performance are studied under different charging pressure. Energy conversion and distribution in the cryocooler are analyzed theoretically. With an electric input power of 10.9 kW and a rotating speed of 1450 r/min of the motor, a cooling power of 700 W at 77 K and a relative Carnot efficiency of 18.2% of the cryocooler have been achieved in the present study, and the corresponding pressure ratio in the compression space reaches 2.46.

  2. Acetone-butanol-ethanol competitive sorption simulation from single, binary, and ternary systems in a fixed-bed of KA-I resin.

    Science.gov (United States)

    Wu, Jinglan; Zhuang, Wei; Ying, Hanjie; Jiao, Pengfei; Li, Renjie; Wen, Qingshi; Wang, Lili; Zhou, Jingwei; Yang, Pengpeng

    2015-01-01

    Separation of butanol based on sorption methodology from acetone-butanol-ethanol (ABE) fermentation broth has advantages in terms of biocompatibility and stability, as well as economy, and therefore gains much attention. In this work a chromatographic column model based on the solid film linear driving force approach and the competitive Langmuir isotherm equations was used to predict the competitive sorption behaviors of ABE single, binary, and ternary mixture. It was observed that the outlet concentration of weaker retained components exceeded the inlet concentration, which is an evidence of competitive adsorption. Butanol, the strongest retained component, could replace ethanol almost completely and also most of acetone. In the end of this work, the proposed model was validated by comparison of the experimental and predicted ABE ternary breakthrough curves using the real ABE fermentation broth as a feed solution. © 2014 American Institute of Chemical Engineers.

  3. New application of plate-fin heat exchanger with regenerative cryocoolers

    Science.gov (United States)

    Chang, Ho-Myung; Gwak, Kyung Hyun

    2015-09-01

    A design idea is newly proposed and investigated for the application of plate-fin heat exchanger (PFHX) with regenerative cryocoolers. The role of this heat exchanger is to effectively absorb heat from the stream of coolant and deliver it to the cold-head of a cryocooler. While various types of tubular HX's have been developed so far, a small PFHX could be more useful for this purpose by taking advantage of compactness and design flexibility. In order to confirm the feasibility and effectiveness, a prototype of aluminum-brazed PFHX is designed, fabricated, and tested with a single-stage GM cryocooler in experiments for subcooling liquid nitrogen from 78 K to 65-70 K. The results show that the PFHX is 30-50% more effective in cooling rate than the tubular HX's. Several potential applications of PFHX are presented and discussed with specific design concepts.

  4. Design and test of the Stirling-type pulse tube cryocooler

    Science.gov (United States)

    Hong, Yong-Ju; Ko, Junseok; Kim, Hyo-Bong; Yeom, Han-Kil; In, Sehwan; Park, Seong-Je

    2017-12-01

    Stirling type pulse tube cryocoolers are very attractive for cooling of diverse application because it has it has several inherent advantages such as no moving part in the cold end, low manufacturing cost and long operation life. To develop the Stirling-type pulse tube cryocooler, we need to design a linear compressor to drive the pulse tube cryocooler. A moving magnet type linear motor of dual piston configuration is designed and fabricated, and this compressor could be operated with the electric power of 100 W and the frequency up to 60 Hz. A single stage coaxial type pulse tube cold finger aiming at over 1.5 W at 80K is built and tested with the linear compressor. Experimental investigations have been conducted to evaluate their performance characteristics with respect to several parameters such as the phase shifter, the charging pressure and the operating frequency of the linear compressor.

  5. Cryocooler-cooled 10 T superconducting magnet; Reitoki chokurei hoshiki no 10T chodendo jishaku

    Energy Technology Data Exchange (ETDEWEB)

    Kuriyama, T.; Yamamoto, K.; Urata, M. [Toshiba Corp., Tokyo (Japan)

    1995-09-01

    A superconducting magnet totally free of such cooling agents as liquefied helium has been developed, which can be cooled by a cryocooler alone in a direct cooler cooled method, and a success was attained when a 10T magnetic field was generated in a vacancy 10cm in diameter. The value is the highest in the world realized by a system not using a cooling medium (only 7.7T attained before this). The coil comprises a coil of an NbTi superconducting lead and a coil of Nb3Sn superconducting lead, and is impregnated with epoxy resin for reduction in size. It is cooled only by heat conduction thanks to a thermally coupled 4K cooler in vacuum, and necessitates the insertion of indium between the coil and a copper made cooling board which combination is further tightened up by a stainless steel wire. Furthermore, a superconducting oxide lead has been developed, with its performance not lowered even in an intensive magnetic field, for the supply of power to the coil, and this suppresses the infiltration of conduction caused heat and the generation of Joule heat. The magnet is designed small and light with dimensions 650{times}500{times}490mm (height), and can be operated by mere manipulation of a switch. 6 refs., 6 figs.

  6. Investigation of a high frequency pulse tube cryocooler driven by a standing wave thermoacoustic engine

    International Nuclear Information System (INIS)

    Boroujerdi, A.A.; Ziabasharhagh, M.

    2014-01-01

    Highlights: • A nonlinear numerical model of a high frequency TADPTC has been developed. • The finite volume method has been used for discretization of governing equations. • The self-excitation process has been simulated very well. • The effects of APAT on the performance of the device have been investigated. • Lagrangian approach has been used to trace the thermodynamic cycle of gas parcels. - Abstract: In this work, a typical thermoacoustically driven pulse tube cooler as a no-moving part device has been investigated by a numerical method. A standing wave thermoacoustic engine as a prime mover in coupled with an inertance tube pulse tube cryocooler has been modeled. Nonlinear equations of unsteady one-dimensional compressible flow have been solved by the finite volume method. The model presents an important step towards the development of nonlinear simulation tools for the high amplitude thermoacoustic systems that are needed for practical use. The results of the computations show that the self-excited oscillations are well accompanied by the increasing of the pressure amplitude. The necessity of implementation of a nonlinear model to investigate such devices has been proven. The effect of APAT length as an amplifier coupler on the performance of the cooler has been investigated. Furthermore, by using Lagrangian approach, thermodynamic cycle of gas parcels has been attained

  7. Development of a hermetically sealed brushless DC motor for a J-T cryocooler

    Science.gov (United States)

    Joscelyn, Edwin; Hochler, Irwin; Ferri, Andrew; Rott, Heinz; Soukaris, Ted

    1996-01-01

    This development was sponsored by Ball Aerospace for the Cryogenic On-Orbit LongLife Active Refrigerator (COOLLAR) program. The cryocooler is designed to cool objects to 65 K and operate in space for at least 7 years. The system also imports minimal impact to the spacecraft in terms of vibration and heat. The basic Joule-Thompson cycle involves compressing a working fluid, nitrogen in this case, at near-constant temperature from 17.2 KPa to 6.89 MPa. The nitrogen is then expanded through a Joule-Thompson valve. The pure nitrogen gas must be kept clean; therefore, any contamination from motor organic materials must be eliminated. This requirement drove the design towards sealing of the motor within a titanium housing without sacrificing motor performance. It is estimated that an unsealed motor would have contributed 1.65 g of contaminants, due to the organic insulation and potting materials, over the 7-year life. This paper describes the motor electrical and mechanical design, as well as the sealing difficulties encountered, along with their solutions.

  8. Characterization of the sorption behavior of trivalent actinides on zirconium(IV) oxide

    Energy Technology Data Exchange (ETDEWEB)

    Eibl, Manuel; Huittinen, Nina [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Virtanen, S.; Merilaeinen, S.; Lehto, J. [Helsinki Univ. (Finland); Rabung, T. [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Nuclear Waste Disposal

    2017-06-01

    The uptake of trivalent Eu and Cm on zirconium(IV) oxide was investigated in batch sorption and TRLFS studies, respectively. Sorption of Eu{sup 3+} was found to start at a pH-value of 4. Based on TRLFS results, sorption of Cm{sup 3+} was assigned to occur through innersphere complex formation at the zirconia surface. A deconvolution of the TRLFS emission spectra gave three different sorption species with strong red-shifts of the peak positions (600.3 nm, 604.3 nm and 608.2 nm) compared to similar systems.

  9. Sorption and diffusion of FE(II) in bentonite

    International Nuclear Information System (INIS)

    Muurinen, A.; Tournassat, C.; Hadi, J.; Greneche, J.-M.

    2014-02-01

    The iron in the engineering barrier system of a nuclear waste repository interacts via the corrosion process with the swelling clay intended as the buffer material. This interaction may affect the sealing properties of the clay. In the case of iron-bentonite interaction, redox reactions, dissolution/precipitation, the diffusion and sorption are coupled together. In a combined study different processes are difficult to distinguish from each other, and more specific studies are needed for the separate processes. In particular, there is a need for well-controlled diffusion and sorption experiments where iron is kept as Fe(II). In this project, sorption and diffusion of Fe(II) in bentonite have been studied. The experiments were carried out under low-oxygen conditions in an anaerobic glove-box. The radioactive isotope ( 55 Fe) was used as a tracer in the experiments. The sorption experiments were carried out with two batches of purified MX-80 bentonite. One was purified at Bureau de Recherches Geologiques et Minieres, French Geological Survey (BRGM) and the other one at VTT Technical Research Centre of Finland (VTT). Experiments were also carried out with synthetic smectite, which did not include iron, which was prepared at LMPC (ENSC, F 68093 Mulhouse, France). The sorption experiments were carried out in 0.3 M and 0.05 M NaCl solutions as a function of pH, and in 0.3 M NaCl solution buffered at pH 5 as a function of added Fe(II) concentration. The separation of bentonite and solution at the end of the sorption experiment was carried out in the early phase by centrifuging only. In the later phase, ultrafiltering was added in order to improve the separation. The diffusion experiments were carried out in compacted samples prepared from MX-80 purified at VTT and saturated with 0.3 M NaCl at pH 8 and 5. A non-steady-state diffusion experiment method, where the tracer was introduced as an impulse source between two bentonite plugs was used in the measurements

  10. Sorption and diffusion of FE(II) in bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Muurinen, A. [VTT Technical Research Centre of Finland, Espoo (Finland); Tournassat, C.; Hadi, J. [BRGM, Orleans (France); Greneche, J.-M. [LPCE, Le Mans (France)

    2014-02-15

    The iron in the engineering barrier system of a nuclear waste repository interacts via the corrosion process with the swelling clay intended as the buffer material. This interaction may affect the sealing properties of the clay. In the case of iron-bentonite interaction, redox reactions, dissolution/precipitation, the diffusion and sorption are coupled together. In a combined study different processes are difficult to distinguish from each other, and more specific studies are needed for the separate processes. In particular, there is a need for well-controlled diffusion and sorption experiments where iron is kept as Fe(II). In this project, sorption and diffusion of Fe(II) in bentonite have been studied. The experiments were carried out under low-oxygen conditions in an anaerobic glove-box. The radioactive isotope ({sup 55}Fe) was used as a tracer in the experiments. The sorption experiments were carried out with two batches of purified MX-80 bentonite. One was purified at Bureau de Recherches Geologiques et Minieres, French Geological Survey (BRGM) and the other one at VTT Technical Research Centre of Finland (VTT). Experiments were also carried out with synthetic smectite, which did not include iron, which was prepared at LMPC (ENSC, F 68093 Mulhouse, France). The sorption experiments were carried out in 0.3 M and 0.05 M NaCl solutions as a function of pH, and in 0.3 M NaCl solution buffered at pH 5 as a function of added Fe(II) concentration. The separation of bentonite and solution at the end of the sorption experiment was carried out in the early phase by centrifuging only. In the later phase, ultrafiltering was added in order to improve the separation. The diffusion experiments were carried out in compacted samples prepared from MX-80 purified at VTT and saturated with 0.3 M NaCl at pH 8 and 5. A non-steady-state diffusion experiment method, where the tracer was introduced as an impulse source between two bentonite plugs was used in the measurements

  11. Use of thermodynamic sorption models to derive radionuclide Kd values for performance assessment: Selected results and recommendations of the NEA sorption project

    Science.gov (United States)

    Ochs, M.; Davis, J.A.; Olin, M.; Payne, T.E.; Tweed, C.J.; Askarieh, M.M.; Altmann, S.

    2006-01-01

    For the safe final disposal and/or long-term storage of radioactive wastes, deep or near-surface underground repositories are being considered world-wide. A central safety feature is the prevention, or sufficient retardation, of radionuclide (RN) migration to the biosphere. To this end, radionuclide sorption is one of the most important processes. Decreasing the uncertainty in radionuclide sorption may contribute significantly to reducing the overall uncertainty of a performance assessment (PA). For PA, sorption is typically characterised by distribution coefficients (Kd values). The conditional nature of Kd requires different estimates of this parameter for each set of geochemical conditions of potential relevance in a RN's migration pathway. As it is not feasible to measure sorption for every set of conditions, the derivation of Kd for PA must rely on data derived from representative model systems. As a result, uncertainty in Kd is largely caused by the need to derive values for conditions not explicitly addressed in experiments. The recently concluded NEA Sorption Project [1] showed that thermodynamic sorption models (TSMs) are uniquely suited to derive K d as a function of conditions, because they allow a direct coupling of sorption with variable solution chemistry and mineralogy in a thermodynamic framework. The results of the project enable assessment of the suitability of various TSM approaches for PA-relevant applications as well as of the potential and limitations of TSMs to model RN sorption in complex systems. ?? by Oldenbourg Wissenschaftsverlag.

  12. Estimation of Freezing Point of Hydrocarbon and Hydrofluorocarbon Mixtures for Mixed Refrigerant jt Cryocooler

    Science.gov (United States)

    Hwang, G.; Lee, J.; Jeong, S.

    2010-04-01

    Estimating the freezing point of refrigerant is an essential part in designing an MR JT (Mixed refrigerant Joule-Thomson) cryocooler to prevent itself from clogging and to operate with stability. There were researches on estimating freezing point, but some of them resulted in the wrong prediction of clogging. In this paper, the freezing point of the MR is precisely estimated with caution of clogging. The solubility of HC (hydrocarbon) and HFC (hydrofluorocarbon) mixture components are obtained with their activity coefficients, which represent the molecular interaction among the components. The freezing points of the MR JT cryocooler are systematically investigated in the operating temperature range from 70 K to 90 K.

  13. Evaluation of sorption distribution coefficient of Cs onto granite using sorption data collected in sorption database and sorption model

    International Nuclear Information System (INIS)

    Nagasaki, S.

    2013-01-01

    Based on the sorption distribution coefficients (K d ) of Cs onto granite collected from the JAERI Sorption Database (SDB), the parameters for a two-site model without the triple-layer structure were optimized. Comparing the experimentally measured K d values of Cs onto Mizunami granite carried out by JAEA with the K d values predicted by the model, the effect of the ionic strength on the K d values of Cs onto granite was evaluated. It was found that K d values could be determined using the content of biotite in granite at a sodium concentration ([Na]) of 1 x 10 -2 to 5 x 10 -1 mol/dm 3 . It was suggested that in high ionic strength solutions, the sorption of Cs onto other minerals such as microcline should also be taken into account. (author)

  14. Evaluation of sorption distribution coefficient of Cs onto granite using sorption data collected in sorption database and sorption model

    Energy Technology Data Exchange (ETDEWEB)

    Nagasaki, S., E-mail: nagasas@mcmaster.ca [McMaster Univ., Hamilton, Ontario (Canada)

    2013-07-01

    Based on the sorption distribution coefficients (K{sub d}) of Cs onto granite collected from the JAERI Sorption Database (SDB), the parameters for a two-site model without the triple-layer structure were optimized. Comparing the experimentally measured K{sub d} values of Cs onto Mizunami granite carried out by JAEA with the K{sub d} values predicted by the model, the effect of the ionic strength on the K{sub d} values of Cs onto granite was evaluated. It was found that K{sub d} values could be determined using the content of biotite in granite at a sodium concentration ([Na]) of 1 x 10{sup -2} to 5 x 10{sup -1} mol/dm{sup 3} . It was suggested that in high ionic strength solutions, the sorption of Cs onto other minerals such as microcline should also be taken into account. (author)

  15. Performance of Cationic Surfactant Modified Sepiolite and Bentonite in Lead Sorption from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    H.R. Rafiei

    2014-12-01

    Full Text Available The remediation of soils and water contaminated with heavy metals generate a great need to develop efficient adsorbents for these pollutants. This study reports the sorption of lead (Pb by bentonite (Bent, and sepiolite (Sep, that were modified with cetyltrimethyl ammonium (CTMA+ organic cations. The natural and surfactant modified clays (organo-clays were characterized with some instrumental techniques including XRF, XRD, FTIR and SEM. Sorption studies were performed in a batch system, and the effects of various experimental parameters including contact time and initial Pb concentration were evaluated upon the Pb sorption onto sorbents. Maximum sorption of Pb was found to be, 83.26, 71.36, 56.25 and 37 mg g-1 for Sep, CTMA-Sep, Bent and CTMA-Bent adsorbents, respectively. The Pb sorption data were fitted to both the Langmuir and Freundlich models. The Freundlich model represented the sorption process better than the Langmuir model. Lead sorption rate was found to be considerably slower for organo-clays than that for unmodified clays. Sorption kinetics was evaluated by pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models. The sorption processes of organo-clays followed intraparticle diffusion kinetics. The results showed that the cationic surfactant modified bentonite and sepiolite sorbed less Pb than the unmodified clays.

  16. Evaluation of sorption affinity of cadmium(II) on Haro river sand from aqueous solutions

    International Nuclear Information System (INIS)

    Hasany, S.M.; Chaudhary, M.H.

    2001-01-01

    The sorption of Cd(II) on Haro river sand from deionized water is reported. The sorption system obeyed according to the Freundlich and Dubinin-Radushkevich (D-R) isotherms. The Freundlich parameters 1/n = 0.67±0.05 and of A = 1.38±1.14 mmole x g -1 have been ascertained. D-R isotherm yields the values of β = -0.003741±0.000321 kJ 2 x mole -2 , X m = 0.23±0.21 μmole x g -1 and of E = 11.6±0.5 kJ x mole -1 . The influence of common anions and cations on the sorption was examined. Trivalent Bi enhances the sorption whereas Fe, Cr, Al and chromate ions reduce the sorption significantly. Hf(IV) and Ag(I) indicate substantial sorption (61-98%) whereas Gd(III), Re(VII) and Sc(III) show low sorption (<5%). The elements having low sorption can be separated from elements indicating higher sorption using Haro river sand column. (author)

  17. Sorption behaviour of well-defined oxidation states

    International Nuclear Information System (INIS)

    Allard, B.; Olofsson, U.; Torstenfelt, B.; Kipatsi, H.

    1983-05-01

    The sorption of the actinides Am(III), Th(IV), Np(V), Pa(V), U(VI) and Pu has been studied as a function of pH (2-12) for two nuclide concentrations (10 -7 -10 -9 M) (only one for Pa and U) in the systems Al 2 0 3 - 0.01 M NaCl0 4 and Si0 2 - 0.01 M NaCl0 4 . Distribution coefficients have been determined by a batch technique after various contact times (6h - 6w) at constant temperature (25degreeC) in systems equilibrated with air. The observed sorption behaviour indicates a predominantly physical adsorption mechanism, where pH of the aqueous phase is the principal chemical parameter of influence. The sorption is highly related to the degree of hydrolysis, with a maximum in the pH-region where neutral species dominate and with a reduction of the sorption under conditions when anionic species (hydroxides or carbonates) would exist in solution. This is particularly the case for U(VI) at pH above 7-8 when anionic carbonate complexes would be formed. Plutonium is predominantly tetravalent under the present conditions, as indicated by the sorption behaviour. (authors)

  18. Sorption isotherms, GAB parameters and isosteric heat of sorption

    NARCIS (Netherlands)

    Quirijns, E.J.; Boxtel, van A.J.B.; Loon, van W.K.P.; Straten, van G.

    2005-01-01

    The diffusion-sorption drying model has been developed as a physics-based way to model the decreasing drying rate at low moisture contents. This new model is founded on the existence of different classes of water: free and bound water. The transition between these classes and the corresponding

  19. High-resolution X-ray crystal structure of bovine H-protein using the high-pressure cryocooling method

    International Nuclear Information System (INIS)

    Higashiura, Akifumi; Ohta, Kazunori; Masaki, Mika; Sato, Masaru; Inaka, Koji; Tanaka, Hiroaki; Nakagawa, Atsushi

    2013-01-01

    Using the high-pressure cryocooling method, the high-resolution X-ray crystal structure of bovine H-protein was determined at 0.86 Å resolution. This is the first ultra-high-resolution structure obtained from a high-pressure cryocooled crystal. Recently, many technical improvements in macromolecular X-ray crystallography have increased the number of structures deposited in the Protein Data Bank and improved the resolution limit of protein structures. Almost all high-resolution structures have been determined using a synchrotron radiation source in conjunction with cryocooling techniques, which are required in order to minimize radiation damage. However, optimization of cryoprotectant conditions is a time-consuming and difficult step. To overcome this problem, the high-pressure cryocooling method was developed (Kim et al., 2005 ▶) and successfully applied to many protein-structure analyses. In this report, using the high-pressure cryocooling method, the X-ray crystal structure of bovine H-protein was determined at 0.86 Å resolution. Structural comparisons between high- and ambient-pressure cryocooled crystals at ultra-high resolution illustrate the versatility of this technique. This is the first ultra-high-resolution X-ray structure obtained using the high-pressure cryocooling method

  20. Sorption, Diffusion and Solubility Databases for Performance Assessment

    International Nuclear Information System (INIS)

    Garcia Gutierrez, M.

    2000-01-01

    This report presents a deterministic and probabilistic databases for application in Performance Assessment of a high-level radioactive waste disposal. This work includes a theoretical description of sorption, diffusion and solubility phenomena of radionuclides in geological media. The report presents and compares the databases of different nuclear wastes management agencies, describes the materials in the Spanish reference system, and the results of sorption diffusion and solubility in this system, with both the deterministic and probabilistic approximation. The probabilistic approximation is presented in the form of probability density functions (pdf). (Author) 52 refs

  1. A suggested approach toward measuring sorption and applying sorption data to repository performance assessment

    International Nuclear Information System (INIS)

    Rundberg, R.S.

    1992-01-01

    The prediction of radionuclide migration for the purpose of assessing the safety of a nuclear waste repository will be based on a collective knowledge of hydrologic and geochemical properties of the surrounding rock and groundwater. This knowledge along with assumption about the interactions of radionuclides with groundwater and minerals form the scientific basis for a model capable of accurately predicting the repository's performance. Because the interaction of radionuclides in geochemical systems is known to be complicated, several fundamental and empirical approaches to measuring the interaction between radionuclides and the geologic barrier have been developed. The approaches applied to the measurement of sorption involve the use of pure minerals, intact, or crushed rock in dynamic and static experiments. Each approach has its advantages and disadvantages. There is no single best method for providing sorption data for performance assessment models which can be applied without invoking information derived from multiple experiments. 53 refs., 12 figs

  2. Recent development status of stirling type pulse tube cryocooler for HTS

    International Nuclear Information System (INIS)

    Hiratsuka, Y; Nakano, K; Kato, T

    2014-01-01

    Sumitomo Heavy Industries, Ltd. (SHI) has been developing a high power stirling type pulse tube cryocooler. For the purpose of cooling high-temperature superconductor (HTS) devices, such as superconductor motor, SMES and current fault limiter, requested specifications from the devices to a cryocooler are compact size, light weight, high efficiency and high reliability. Especially, the cryocooler must be demanded COP > 0.1 in the efficiency. The experimental results of prototype pulse tube cryocooler were reported in June 2012 [1]. For an In-line type expander, the cooling capacity was 210 W at 77 K and the minimum temperature was 37 K when the compressor input power was 3.8 kW and the operating frequency was 49 Hz. Accordingly, COP was about 0.055. Moreover, for miniaturization a U type expander was tested and the performance is about 10 % less than that of an In-line type expander. After that, we have estimated that the cooling performance is influenced by the environment such as the effect of the pulse-tube inclination, the temperature and the flowing quantity of cooling water. The detailed results are reported in this paper.

  3. Analysis and comparison of different phase shifters for Stirling pulse tube cryocooler

    DEFF Research Database (Denmark)

    Lei, Tian; Pfotenhauer, John M.; Zhou, Wenjie

    2016-01-01

    Investigations of phase shifters and power recovery mechanisms are of sustainable interest for developing Stirling pulse tube cryocoolers (SPTC) with higher power density, more compact design and higher efficiency. This paper investigates the phase shifting capacity and the applications of four...

  4. Sorption on inactive repository components

    International Nuclear Information System (INIS)

    Gardiner, M.P.; Smith, A.J.; Williams, S.J.

    1990-11-01

    The near-field of an intermediate level/low level radioactive waste repository will contain significant quantities of iron and steel, Magnox and Zircaloy. Their corrosion products may possess significant sorption capacity for radioelements. The sorption of americium and plutonium onto magnesium hydroxide, zirconium hydroxide, colloidal magnetite and colloidal haematite has been studied under conditions typical of the porewater of a cementitious near-field. R D values ≥ 10 5 m g -1 were measured for both actinides on the oxides and hydroxides. These values are at least as great as those measured on crushed 3:1 Blast Furnace Slag/Ordinary Portland cement. Competitive sorption experiments have shown that sorption onto the corrosion products does not take place in preference to that on the cement or the converse. Magnetite and haematite colloids are positively charged in cement-equilibrated water whilst zirconium hydroxide is negatively charged. Crushed cement was found to be positively charged. Simple experiments show that only a small proportion of haematite colloids is potentially mobile through a column of crushed cement. (author)

  5. Sorption on inactive repository components

    International Nuclear Information System (INIS)

    Gardiner, M.P.; Smith, A.J.; Williams, S.J.

    1990-07-01

    The near-field of an intermediate level/low level radioactive waste repository will contain significant quantities of iron and steel, Magnox and Zircaloy. Their corrosion products may possess significant sorption capacity for radioelements. The sorption of americium and plutonium onto magnesium hydroxide, zirconium hydroxide, colloidal magnetite and colloidal haematite has been studied under conditions typical of the porewater of a cementitious near-field. R D values ≥ 10 5 ml g -1 were measured for both actinides on the oxides and hydroxides. These values are at least as great at those measured on crushed 3:1 Blast Furnace Slag/Ordinary Portland Cement. Competitive sorption experiments have shown that sorption onto the corrosion products does not take place in preference to that on the cement or the converse. Magnetite and haematite colloids are positively charged in cement-equilibrated water whilst zirconium hydroxide is negatively charged. Crushed cement was found to be positively charged. Simple experiments show that only a small proportion of haematite colloids is potentially mobile through a column of crushed cement. (author)

  6. Comparative study about hydrogen sorption in sponge and powder titanium

    International Nuclear Information System (INIS)

    Vasut, Felicia; Preda, Anisoara; Zamfirache, Marius; Ducu, Catalin; Malinovschi, Viorel

    2005-01-01

    Currently, hydrogen may be stored as a compressed gas or a cryogenic liquid. Neither method appears to be practical for many applications in which hydrogen use would otherwise be attractive. For example, gaseous storage of stationary fuel is not feasible because of the large volume or weight of the storage vessels. Liquid hydrogen could be use extensively but the liquefaction process is relatively expensive. The hydrogen can be stored for a long term with a high separation factor, as a solid metal hydride. Using hydride-forming metals and intermetallic compounds, for example, recovery, purification and storage of heavy isotopes in tritium containing system, can solve many problems arising in the nuclear-fuel cycle. The paper presents a comparative study about hydrogen sorption on two titanium structures: powder and sponge. Also, it is presented the characterization, by X-Ray diffraction, of two structures, before and after sorption process. From our results, one can conclude that sorption method is efficient for both samples. Kinetic curves indicates that sorption rate for titanium powder is lower than for sponge titanium. This is the effect of reaction surface, which is larger for powder titanium. Sorption capacity for hydrogen is lower in powder titanium for identical experimental conditions. The difference between storage capacities could be explained by activation temperature, which was lower for titanium powder than for sponge. (authors)

  7. Sorption of Emerging Organic Wastewater Contaminants to Four Soils

    Directory of Open Access Journals (Sweden)

    Sarah Roberts

    2014-04-01

    Full Text Available Conventional onsite wastewater treatment system design relies on a septic tank and soil treatment unit (STU for treatment of wastewater and integration of the final effluent into the environment. Organic water contaminants (OWCs, chemicals found in pharmaceutical drugs, detergents, surfactants, and other personal care and cleaning products, have been observed in septic tank effluent and the environment. Sorption of OWC mass to soil is a key mechanism in the removal and retardation of many of these chemicals in effluent as it travels through an STU. The primary purpose of this study was to investigate the relationship between the fraction of organic carbon of soil and the equilibrium sorption partitioning coefficient of a selected group of relevant and diverse OWCs. A secondary goal is to evaluate current methods of modeling the sorption of selected OWCs in soil. Five point Freundlich isotherms were constructed from equilibrium sorption batch tests for target OWCs with four different soils. For soils with organic carbon fraction between 0.021 and 0.054, Kd values were calculated between 60 and 185 for 4-nonylphenol, 75 to 260 for triclosan, 115 to 270 for bisphenol-A, 3 to 255 for 17β-estradiol, 40 to 55 for 17α-ethynylestradiol, and 28 to 70 for estrone. An empirically derived, direct relationship between foc and Kd may be a useful approach to estimating sorption for a soil based on organic carbon content.

  8. Sorption/desorption reversibility of polycyclic aromatic hydrocarbons (PAHs) in soils and carbonaceous materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guohui

    2008-07-01

    Understanding sorption/desorption is an important prerequisite for the prediction of fate and transport of pollutants in the environment. During the last two decades, numerous studies have reported hysteresis phenomenon for the interaction of hydrophobic organic contaminants (HOCs) with natural organic matter (NOM). It manifests as nonsingular sorption/desorption isotherms or different rates for sorption and desorption, where during desorption a higher affinity of a compound on a given sorbent and a longer time scale for release than for sorption is observed. Other studies showed that some of the reported sorption/desorption hysteresis phenomena are due to experimental artifacts, mainly resulting from non-attainment of sorption equilibrium before desorption experiments, which result in 'pseudo-hysteresis'. Except for the hypothesis of sorbent reconfiguration, clear experimental evidence for the physical or chemical mechanisms proposed to lead to hysteresis is still lacking. In this study, sorption/desorption equilibrium and kinetics of phenanthrene sorption/desorption from two soils and three carbonaceous samples were investigated using both batch and column techniques. The main objective of this work was to monitor hysteresis phenomenon by carefully recovering the solute mass in the system and to compare sorption/desorption equilibria and kinetics thermodynamically. Nonsingular isotherms and higher desorption enthalpies as well as increased activation energies with proceeding desorption are expected if significant hysteresis exists. Sorption-desorption cycles were carried out to compare equilibrium isotherms and associated sorption/desorption enthalpies (AeH, isosteric heats). Instead of the traditional decant-and-refill batch method, the experiments were conducted using a newly designed batch protocol, which enables the determination of sorption/desorption isotherms at different temperatures using a closed batch system. This method additionally allows

  9. Sorption/desorption reversibility of polycyclic aromatic hydrocarbons (PAHs) in soils and carbonaceous materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guohui

    2008-07-01

    Understanding sorption/desorption is an important prerequisite for the prediction of fate and transport of pollutants in the environment. During the last two decades, numerous studies have reported hysteresis phenomenon for the interaction of hydrophobic organic contaminants (HOCs) with natural organic matter (NOM). It manifests as nonsingular sorption/desorption isotherms or different rates for sorption and desorption, where during desorption a higher affinity of a compound on a given sorbent and a longer time scale for release than for sorption is observed. Other studies showed that some of the reported sorption/desorption hysteresis phenomena are due to experimental artifacts, mainly resulting from non-attainment of sorption equilibrium before desorption experiments, which result in 'pseudo-hysteresis'. Except for the hypothesis of sorbent reconfiguration, clear experimental evidence for the physical or chemical mechanisms proposed to lead to hysteresis is still lacking. In this study, sorption/desorption equilibrium and kinetics of phenanthrene sorption/desorption from two soils and three carbonaceous samples were investigated using both batch and column techniques. The main objective of this work was to monitor hysteresis phenomenon by carefully recovering the solute mass in the system and to compare sorption/desorption equilibria and kinetics thermodynamically. Nonsingular isotherms and higher desorption enthalpies as well as increased activation energies with proceeding desorption are expected if significant hysteresis exists. Sorption-desorption cycles were carried out to compare equilibrium isotherms and associated sorption/desorption enthalpies (AeH, isosteric heats). Instead of the traditional decant-and-refill batch method, the experiments were conducted using a newly designed batch protocol, which enables the determination of sorption/desorption isotherms at different temperatures using a closed batch system. This method additionally allows the

  10. Sorption compressor/mechanical expander hybrid refrigeration

    Science.gov (United States)

    Jones, J. A.; Britcliffe, M.

    1987-01-01

    Experience with Deep Space Network (DSN) ground-based cryogenic refrigerators has proved the reliability of the basic two-stage Gifford-McMahon helium refrigerator. A very long life cryogenic refrigeration system appears possible by combining this expansion system or a turbo expansion system with a hydride sorption compressor in place of the usual motor driven piston compressor. To test the feasibility of this system, a commercial Gifford-McMahon refrigerator was tested using hydrogen gas as the working fluid. Although no attempt was made to optimize the system for hydrogen operation, the refrigerator developed 1.3 W at 30 K and 6.6 W at 60 K. The results of the test and of theoretical performances of the hybrid compressor coupled to these expansion systems are presented.

  11. Thermal properties of a large-bore cryocooled 10 T superconducting magnet for a hybrid magnet

    International Nuclear Information System (INIS)

    Ishizuka, M.; Hamajima, T.; Itou, T.; Sakuraba, J.; Nishijima, G.; Awaji, S.; Watanabe, K.

    2010-01-01

    A cryocooled 10 T superconducting magnet with a 360 mm room temperature bore has been developed for a hybrid magnet. The superconducting magnet cooled by four Gifford-McMahon cryocoolers has been designed to generate a magnetic field of 10 T. Since superconducting wires composed of coils were subjected to large hoop stress over 150 MPa and Nb 3 Sn superconducting wires particularly showed a low mechanical strength due to those brittle property, Nb 3 Sn wires strengthened by NbTi-filaments were developed for the cryocooled superconducting magnet. We have already reported that the hybrid magnet could generate the resultant magnetic field of 27.5 T by adding 8.5 T from the superconducting magnet and 19 T from a water-cooled Bitter resistive magnet, after the water-cooled resistive magnet was inserted into the 360 mm room temperature bore of the cryocooled superconducting magnet. When the hybrid magnet generated the field of 27.5 T, it achieved the high magnetic-force field (B x ∂Bz/∂z) of 4500 T 2 /m, which was useful for magneto-science in high fields such as materials levitation research. In this paper, we particularly focus on the cause that the cryocooled superconducting magnet was limited to generate the designed magnetic field of 10 T in the hybrid magnet operation. As a result, it was found that there existed mainly two causes as the limitation of the magnetic field generation. One was a decrease of thermal conductive passes due to exfoliation from the coil bobbin of the cooling flange. The other was large AC loss due to both a thick Nb 3 Sn layer and its large diameter formed on Nb-barrier component in Nb 3 Sn wires.

  12. Radionuclide and metal sorption on cement and concrete

    CERN Document Server

    Ochs, Michael; Wang, Lian

    2016-01-01

    Cementitious materials are being widely used as solidification/stabilisation and barrier materials for a variety of chemical and radioactive wastes, primarily due to their favourable retention properties for metals, radionuclides and other contaminants. The retention properties result from various mineral phases in hydrated cement that possess a high density and diversity of reactive sites for the fixation of contaminants through a variety of sorption and incorporation reactions. This book presents a state of the art review and critical evaluation of the type and magnitude of the various sorption and incorporation processes in hydrated cement systems for twenty-five elements relevant for a broad range of radioactive and industrial wastes. Effects of cement evolution or ageing on sorption/incorporation processes are explicitly evaluated and quantified. While the immobilisation of contaminants by mixing-in during hydration is not explicitly addressed, the underlying chemical processes are similar. A quantitativ...

  13. Sorption behaviour of caesium on a bentonite sample

    International Nuclear Information System (INIS)

    Hurel, C.; Marmier, N.; Fromage, F.; Seby, F.; Bourg, A.C.M.; Giffaut, E.

    2002-01-01

    Sorption of elements like Cs on clay is one of the principal processes delaying their release from deep repositories of nuclear wastes into the environment. The sorption processes taking place between non-purified natural clay material (bentonite) and synthetic groundwater (containing Ca, Mg, Na, K and carbonates) were therefore studied experimentally and modelled for Cs to determine whether thermodynamic computer codes capable of predicting the behaviour of this element in natural systems might be developed. The model used, based on the properties of a pure montmorillonite phase, incorporates the surface reactions for natural major ions and sorbing cations but does not have any adjustable parameters. The weight of each parameters used in the model is assessed. Surface reactions are classified as either major or minor, and a simplified model of Cs sorption that considers only the major processes is proposed. This simplified model might correspond to the less sophisticated thermodynamic model included in coupled geochemistry-transport models. (orig.)

  14. Investigation of strontium sorption on Kula volcanites treated with HCl

    International Nuclear Information System (INIS)

    Kuetahyali, C.; Cetinkaya, B.; Acar, M. B.; Isik, N. O.; Cireli, I.

    2009-01-01

    In planning the disposal of radioactive waste in a deep geologic repository, consideration must be given to the ways in which radionuclides might leave the repository and migrate through the geosphere. In performance assessment studies the uptake of the radioactive elements by rock formations play an important role in retarding their aqueous phase migration. Sorption studies of radionuclides have been conducted to obtain data on the distribution coefficient (K d ) that is as an input parameter in the performance assessment of the geological disposal of radioactive wastes. In many studies, the sorption experiments employed natural soils and rocks as sorbents. Adsorption experiments were studied in a batch adsorption system using Sr(NO 3 ) 2 (Merck) solution. Strontium sorption on Kula Volcanites treated with HCl was investigated. Central Composite Design Method was used in the experiments. Sr adsorption was studied as a function of pH, contact time, concentration of adsorbate, and temperature.

  15. Cerium sorption in grounds modified by anti-deflation treatment

    International Nuclear Information System (INIS)

    Firsova, L.P.; Bogatyrev, I.O.

    2001-01-01

    Influence of soils and grounds treatment by anti-deflation compositions on the size of the soil particles was studied. Under static conditions sorption of 144 Ce by turf-podsolic soils prior to an after their modification by the anti-deflation reagents, i.e. bitumens and insoluble in water polyelectrolytic complexes, was considered. Degrees of 144 Ce sorption in the soil-solution systems, depending on solutions pH, presence of alkali metal carbonates and cerium concentration, were determined [ru

  16. EXAFS study of plutonium sorption onto kaolinite

    International Nuclear Information System (INIS)

    Reich, T.Y.; Banik, L.; Buda, R.A.; Amayri, S.; Drebert, J.; Kratz, J.V.; Trautmann, N.; Reich, T.; Ageev, A.L.; Korshunov, M.E.

    2007-01-01

    The uptake mechanism of plutonium by kaolinite was investigated by applying X-ray absorption spectroscopy to batch sorption samples (total Pu concentrations 1 and 10 μM; 4 g kaolinite/L in 0.1 M NaClO 4 ; 1 ≤ pH ≤ 9; presence and absence of ambient CO 2 ). For XAFS measurements, one sample was prepared from a Pu(III) solution at pH 6 under argon atmosphere. Three samples were obtained by sorption of Pu(IV) at pH I, 4, and 9 in an air-equilibrated system. The Pu L III -edge XANES spectra indicated that in all samples, including the Pu(III) sample, plutonium is sorbed at the kaolinite surface as Pu(IV). The Pu L III -edge k 3 -weighted EXAFS spectra showed eight oxygen atoms at an average Pu-O distance of 2.3 angstrom. Two Pu atoms were detected at ∼ 3.7 angstrom in all spectra, indicating the formation of polynuclear Pu(IV) species at the kaolinite surface. For the sample prepared from Pu(III) solution, an additional Pu-O shell at 3.2 angstrom was observed. The spectra of samples prepared from Pu(IV) included a Pu-Al/Si co-ordination shell at approximately 3.6 angstrom, indicating formation of inner-sphere sorption complexes. The structural models used in the least-squares fits were confirmed by an alternative EXAFS data analysis approach based on a modified Tikhonov regularization method. (authors)

  17. Uranium sorption on tezontle volcanic rock

    Energy Technology Data Exchange (ETDEWEB)

    Lopez M, B. E.; Duran B, J. M.; Iturbe G, J. L.; Olguin G, M. T., E-mail: beatriz.lopez@inin.gob.m [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2009-07-01

    It is described a study that demonstrates that hexavalent uranium ions were sorbed by the naturally occurring mineral using a batch technique. This mineral is found in abundant quantities in Mexico. Our study focused on the separation of U Vi from synthetic aqueous systems of both H{sub 2}O-UO{sub 2}(NO{sub 3}){sub 2}.6H{sub 2}O (acid) and H{sub 2}O-Na{sub 4}[UO{sub 2}(CO{sub 3}){sub 3}] (basic). The chemical speciation was performed by using high voltage electrophoresis, and the uranium content was determined by UV-Vis spectroscopy. The quantified U(Vi) sorption by tezontle from acidic and basic systems was 2.72 and 1.68 mumol/g, respectively, and the sorption behavior is discussed considering the surface charge of the tezontle at different ph values based on the point of zero charge characteristic of this material. (Author)

  18. Multiobjective optimizations of a novel cryocooled dc gun based ultrafast electron diffraction beam line

    Directory of Open Access Journals (Sweden)

    Colwyn Gulliford

    2016-09-01

    Full Text Available We present the results of multiobjective genetic algorithm optimizations of a single-shot ultrafast electron diffraction beam line utilizing a 225 kV dc gun with a novel cryocooled photocathode system and buncher cavity. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at the sample location have been performed for three different sample radii: 50, 100, and 200  μm, for two final bunch charges: 10^{5} electrons (16 fC and 10^{6} electrons (160 fC. Example optimal solutions are analyzed, and the effects of disordered induced heating estimated. In particular, a relative coherence length of L_{c,x}/σ_{x}=0.27  nm/μm was obtained for a final bunch charge of 10^{5} electrons and final bunch length of σ_{t}≈100  fs. For a final charge of 10^{6} electrons the cryogun produces L_{c,x}/σ_{x}≈0.1  nm/μm for σ_{t}≈100–200  fs and σ_{x}≥50  μm. These results demonstrate the viability of using genetic algorithms in the design and operation of ultrafast electron diffraction beam lines.

  19. Influence of the isomerism on the sorption of imazamethabenz-methyl by soil.

    Science.gov (United States)

    Pinna, Maria Vittoria; Pusino, Alba

    2013-04-01

    The sorption of meta and para isomers of the herbicide imazamethabenz-methyl, methyl 6-[(RS)-4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl]-m- or p-toluate, by three soils and soil organic matter, was studied. Sorption isotherms conformed to the Freundlich equation. It was found that pH was the main factor influencing the adsorption in all of the systems. The highest level of sorption was measured on soils with low pH and high organic carbon content. Moreover, at low pH value, the soil rich in smectite clays, favoured the sorption of meta rather than para isomer. The higher affinity of clay surfaces for the meta isomer of the herbicide is due to the stabilization of the meta protonated form by resonance. At all pH values, the sorption on soil organic matter did not differ between two isomers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. The sorption behavior of DDT onto sediment in the presence of surfactant cetyltrimethylammonium bromide

    International Nuclear Information System (INIS)

    Cao Xiaoyan; Han Huayu; Yang Guipeng; Gong Xiaofei; Jing Jianning

    2011-01-01

    Highlights: → The sorption behavior of a complex system consists of DDT and CTAB onto marine sediment was studied. → Batch experiments were carried out to investigate the kinetics and thermodynamics. → The presence of CTAB could remarkably accelerate and enhance the sorption of DDT. → The sorption of DDT had relatively more negative ΔG 0 and ΔH 0 in the presence of CTAB. - Abstract: The sorption behavior of p,p'- and o,p'-dichlorodiphenyltrichloroethane (DDT) in the presence of a cationic surfactant cetyltrimethylammonium bromide (CTAB) on sediment was studied. Batch experiments were carried out to investigate the kinetics and thermodynamics of the process. The kinetic behavior of these three chemicals on sediment was described by pseudo-second-order kinetic equations, and the isotherms followed the Freundlich model well. The presence of CTAB was able to remarkably accelerate and enhance the sorption of DDT, whereas DDT showed no effect on the sorption of CTAB in our considered concentration ranges. The thermodynamic parameters, such as standard enthalpy change (ΔH 0 ), standard entropy change (ΔS 0 ) and standard Gibbs free energy change (ΔG 0 ) showed that the sorption process of p,p'- and o,p'-DDT was physical, spontaneous and exothermic, and the randomness at the solid-liquid interface increased during the process. In the presence of CTAB, the sorption of DDT showed significantly negative ΔG 0 and ΔH 0 values.

  1. The sorption induced glass transition in amorphous glassy polymers

    NARCIS (Netherlands)

    van der Vegt, N.F.A.; Wessling, Matthias; Strathmann, H.; Briels, Willem J.

    1999-01-01

    Sorption of CO2 in both the glassy and the rubbery state of an amorphous polyethylenelike polymer was investigated using molecular dynamics simulations. The temperature was chosen such that the system was in its glassy state at low solute concentrations and its rubbery state at large solute

  2. Heavy metal removal from aqueous solutions by sorption using ...

    African Journals Online (AJOL)

    Heavy metal removal from aqueous solutions by sorption using natural clays from Burkina Faso. ... The high alkaline pH in one of the samples is attributable to the presence of ... The point of zero charge (pHpzc) values of the clays, as determined by ... significant contributions to the removal of metal ions in aqueous systems.

  3. Sorption isotherms: A review on physical bases, modeling and measurement

    Energy Technology Data Exchange (ETDEWEB)

    Limousin, G. [Atomic Energy Commission, Tracers Technology Laboratory, 38054 Grenoble Cedex (France) and Laboratoire d' etude des Transferts en Hydrologie et Environnement (CNRS-INPG-IRD-UJF), BP 53, 38041 Grenoble Cedex (France)]. E-mail: guillaumelimousin@yahoo.fr; Gaudet, J.-P. [Laboratoire d' etude des Transferts en Hydrologie et Environnement (CNRS-INPG-IRD-UJF), BP 53, 38041 Grenoble Cedex (France); Charlet, L. [Laboratoire de Geophysique Interne et Techtonophysique - CNRS-IRD-LCPC-UJF-Universite de Savoie, BP 53, 38041 Grenoble Cedex (France); Szenknect, S. [Atomic Energy Commission, Tracers Technology Laboratory, 38054 Grenoble Cedex (France); Barthes, V. [Atomic Energy Commission, Tracers Technology Laboratory, 38054 Grenoble Cedex (France); Krimissa, M. [Electricite de France, Division Recherche et Developpement, Laboratoire National d' Hydraulique et d' Environnement - P78, 6 quai Watier, 78401 Chatou (France)

    2007-02-15

    The retention (or release) of a liquid compound on a solid controls the mobility of many substances in the environment and has been quantified in terms of the 'sorption isotherm'. This paper does not review the different sorption mechanisms. It presents the physical bases underlying the definition of a sorption isotherm, different empirical or mechanistic models, and details several experimental methods to acquire a sorption isotherm. For appropriate measurements and interpretations of isotherm data, this review emphasizes 4 main points: (i) the adsorption (or desorption) isotherm does not provide automatically any information about the reactions involved in the sorption phenomenon. So, mechanistic interpretations must be carefully verified. (ii) Among studies, the range of reaction times is extremely wide and this can lead to misinterpretations regarding the irreversibility of the reaction: a pseudo-hysteresis of the release compared with the retention is often observed. The comparison between the mean characteristic time of the reaction and the mean residence time of the mobile phase in the natural system allows knowing if the studied retention/release phenomenon should be considered as an instantaneous reversible, almost irreversible phenomenon, or if reaction kinetics must be taken into account. (iii) When the concentration of the retained substance is low enough, the composition of the bulk solution remains constant and a single-species isotherm is often sufficient, although it remains strongly dependent on the background medium. At higher concentrations, sorption may be driven by the competition between several species that affect the composition of the bulk solution. (iv) The measurement method has a great influence. Particularly, the background ionic medium, the solid/solution ratio and the use of flow-through or closed reactor are of major importance. The chosen method should balance easy-to-use features and representativity of the studied

  4. Sorption and desorption of carbamazepine from water by smectite clays.

    Science.gov (United States)

    Zhang, Weihao; Ding, Yunjie; Boyd, Stephen A; Teppen, Brian J; Li, Hui

    2010-11-01

    Carbamazepine is a prescription anticonvulsant and mood stabilizing pharmaceutical administered to humans. Carbamazepine is persistent in the environment and frequently detected in water systems. In this study, sorption and desorption of carbamazepine from water was measured for smectite clays with the surface negative charges compensated with K+, Ca2+, NH4+, tetramethylammonium (TMA), trimethylphenylammonium (TMPA) and hexadecyltrimethylammonium (HDTMA) cations. The magnitude of sorption followed the order: TMPA-smectite≥HDTMA-smectite>NH4-smectite>K-smectite>Ca-smectite⩾TMA-smectite. The greatest sorption of carbamazepine by TMPA-smectite is attributed to the interaction of conjugate aromatic moiety in carbamazepine with the phenyl ring in TMPA through π-π interaction. Partitioning process is the primary mechanism for carbamazepine uptake by HDTMA-smectite. For NH4-smectite the urea moiety in carbamazepine interacts with exchanged cation NH4+ by H-bonding hence demonstrating relatively higher adsorption. Sorption by K-, Ca- and TMA-smectites from water occurs on aluminosilicate mineral surfaces. These results implicate that carbamazepine sorption by soils occurs primarily in soil organic matter, and soil mineral fractions play a secondary role. Desorption of carbamazepine from the sorbents manifested an apparent hysteresis. Increasing irreversibility of desorption vs. sorption was observed for K-, Ca-, TMA-, TMPA- and HDTMA-clays as aqueous carbamazepine concentrations increased. Desorption hysteresis of carbamazepine from K-, Ca-, NH4-smectites was greater than that from TMPA- and HDTMA-clays, suggesting that the sequestrated carbamazepine molecules in smectite interlayers are more resistant to desorption compared to those sorbed by organic phases in smectite clays. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Sorption mechanisms of metals to graphene oxide

    International Nuclear Information System (INIS)

    Showalter, Allison R; Bunker, Bruce A; Duster, Thomas A; Szymanowski, Jennifer E S; Na, Chongzheng; Fein, Jeremy B

    2016-01-01

    Environmental toxic metal contamination remediation and prevention is an ongoing issue. Graphene oxide is highly sorptive for many heavy metals over a wide pH range under different ionic strength conditions. We present x-ray absorption fine structure (XAFS) spectroscopy results investigating the binding environment of Pb(II), Cd(II) and U(VI) ions onto multi-layered graphene oxide (MLGO). Analysis indicates that the dominant sorption mechanism of Pb to MLGO changes as a function of pH, with increasing inner sphere contribution as pH increases. In contrast, the sorption mechanism of Cd to MLGO remains constant under the studied pH range. This adsorption mechanism is an electrostatic attraction between the hydrated Cd +2 ion and the MLGO surface. The U(VI), present as the uranyl ion, changes only subtly as a function of pH and is bound to the surface via an inner sphere bond. Knowledge of the binding mechanism for each metal is necessary to help in optimizing environmental remediation or prevention in filtration systems. (paper)

  6. Sorption of fission nuclides on model milk components. I. Sorption of radiostrontium on hydroxyapatite in aqueous solutions

    International Nuclear Information System (INIS)

    Rosskopfova, O.; Kopunec, R.; Matel, L.; Macasek, F.; Kristin, J.

    1999-01-01

    Hydroxyapatite, Ca 10 (PO 4 ) 6 (OH) 2 is a mineral widely spread in nature as a main constituent of phosphate rocks, and also as the major inorganic component of bones and teeth. It was found that sorption process occurs by an ion exchange reaction mechanism between strontium ions in solution and calcium ions in apatite. Ca 2+ → Sr 2+ substitution in hydroxyapatite is important since it explains the mechanism of incorporation of beta-active Sr-90 of atomic debris into the human skeletal system. The strontium uptake at 100 grad C is done by adsorption and diffusion while at 25 grad C it is done by the process of adsorption only. The hydroxyapatite was prepared from aqueous solutions and characterized by standard analytical methods. Some samples of hydroxyapatite were modified by heating after its precipitation from aqueous solution. The sample obtained had characteristics of well crystallized stoichiometric hydroxyapatite. Also, commercial hydroxy-apatites were used. Sorption of strontium ions on synthetic hydroxyapatite was examined using batch method and sorption depends on the method of preparation of hydroxyapatite. In generally, sorption of strontium decreases with the increase in the particle size of hydroxyapatite and decreases with the increase in the pH ( hydroxyapatite surface is amphoteric and acts as a buffer in a wide pH range). The sorption of strontium increases with the increase in [Sr 2+ ] or [Ca 2+ ] in solution to ∼ 10 -5 mol · dm -3 for the hydroxyapatite prepared by heating. The experimental data for sorption of strontium has been fitted with Langmuir-adsorption isotherm. (authors)

  7. Sorption Energy Maps of Clay Mineral Surfaces

    International Nuclear Information System (INIS)

    Cygan, Randall T.; Kirkpatrick, R. James

    1999-01-01

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

  8. Applicability of microautoradiography to sorption studies

    International Nuclear Information System (INIS)

    Thompson, J.L.; Wolfsberg, K.

    1979-01-01

    The technique of microautoradiography was applied to the study of the sorption of uranium and americium on five rock types which exist at the Nevada Test Site. It was found that autoradiograms could be prepared in a few days which would allow the specific minerals responsible for sorption to be identified. Furthermore, the state of aggregation of the sorbed species was clearly indicated. It was concluded that microautoradiography was a useful adjunct to currently used methods for studying sorption of certain radionuclides

  9. Binary Component Sorption of Cadmium, and Copper Ions onto Yangtze River Sediments with Different Particle Sizes

    Directory of Open Access Journals (Sweden)

    Jianxin Fan

    2017-11-01

    Full Text Available Sorption is a crucial process that influences immobilization and migration of heavy metals in an aqueous environment. Sediments represent one of the ultimate sinks for heavy metals discharged into water body. Moreover, the particle size of sediments plays an extremely important role in the immobilization of heavy metals. In this study, the sorption and desorption of cadmium (Cd and copper (Cu onto sediments with different particle sizes were investigated to predict the rate and capacity of sorption, to understand their environmental behaviors in an aqueous environment. Batch sorption and kinetic experiments were conducted to obtain the retained amount and rate of Cd and Cu in a binary system. Experimental data were simulated using sorption models to ascertain the sorption capacity and the kinetic rate. Results of European Communities Bureau of Reference (BCR sequential extraction showed the highest concentration of Cd (0.344 mg kg−1, and its distribution varied with sediment particle size and site. Furthermore, most of Cu (approximately 57% to 84% existed as a residual fraction. The sorption of Cu onto six sediments followed a pseudo-first order reaction, whereas that of Cd followed a pseudo-second order reaction. Additionally, the competitive Langmuir model fitted the batch sorption experimental data extremely well. The highest sorption capacities of Cd and Cu reach 0.641 mmol kg−1 and 62.3 mmol kg−1, respectively, on the smallest submerged sediment particles. The amounts of Cu and Cd desorbed (mmol kg−1 increased linearly with the initial concentration increasing. Thus, sediment texture is an important factor that influences the sorption of heavy metal onto sediments.

  10. Kinetics and equilibrium modeling of uranium(VI) sorption by bituminous shale from aqueous solution

    International Nuclear Information System (INIS)

    Ortaboy, Sinem; Atun, Gülten

    2014-01-01

    Highlights: • Oil shales are sedimentary rocks containing a polymeric matter in a mineral matrix. • Sorption potential of bituminous shale (BS) for uranium recovery was investigated. • U(VI) sorption increased with decreasing pH and increasing temperature. • Kinetic data were analyzed based on single and two resistance diffusion models. • The results fit well to the McKay equation assuming film and intraparticle diffusion. - Abstract: Sorption of U(VI) onto a bituminous shale (BS) from a nuclear power plant project site in Black Sea region was investigated for potential risk assessment when it releases into the environment with contaminated ground and surface water. The sorption characteristics of the BS for U(VI) recovery were evaluated as a function of contact time, adsorbent dosage, initial concentration, pH and temperature. Kinetic results fit better with pseudo-second-order model rather than pseudo-first-order. The possibility of diffusion process was analyzed based on Weber–Morris intra-particle diffusion model. The McKay equation assuming film- and intraparticle diffusion better predicted the data than the Vermeulen approximation presuming surface diffusion. Equilibrium sorption data were modeled according to the Langmuir, Dubinin–Radushkevich (D–R) and Freundlich isotherm equations. Sorption capacity increased from 0.10 to 0.15 mmol g −1 in 298–318 K temperature range. FT-IR analysis and pH dependent sorption studies conducted in hydroxide and carbonate media revealed that U(VI) species were sorbed in uranyl and its hydroxo forms on the BS. Desorption studies showed that U(VI) leaching with Black Sea water was negligible from the loaded BS. The activation parameters (E a , ΔH ∗ and ΔG ∗ ) estimated from diffusion coefficients indicated the presence of an energy barrier in the sorption system. However, thermodynamic functions derived from sorption equilibrium constants showed that overall sorption process was spontaneous in nature

  11. Experimental study and modelling of selenite sorption onto illite and smectite clays.

    Science.gov (United States)

    Missana, T; Alonso, U; García-Gutiérrez, M

    2009-06-15

    This study provides a large set of experimental selenite sorption data for pure smectite and illite. Similar sorption behavior existed in both clays: linear within a large range of the Se concentrations investigated (from 1x10(-10) to 1x10(-3) M); and independent of ionic strength. Selenite sorption was also analysed in the illite/smectite system with the clays mixed in two different proportions, as follows: (a) 30% illite-70% smectite and (b) 43% illite-57% smectite. The objective of the study was to provide the simplest model possible to fit the experimental data, a model also capable of describing selenite sorption in binary illite/smectite clay systems. Selenite sorption data, separately obtained in the single mineral systems, were modeled using both a one- and a two-site non-electrostatic model that took into account the formation of two complexes at the edge sites of the clay. Although the use of a two-site model slightly improved the fit of data at a pH below 4, the simpler one-site model reproduced satisfactorily all the sorption data from pH 3 to 8. The complexation constants obtained by fitting sorption data of the individual minerals were incorporated into a model to predict the adsorption of selenium in the illite/smectite mixtures; the model's predictions were consistent with the experimental adsorption data.

  12. Aminosilane-Functionalized Cellulosic Polymer for Increased Carbon Dioxide Sorption

    KAUST Repository

    Pacheco, Diana M.

    2012-01-11

    Improvement in the efficiency of CO 2 separation from flue gases is a high-priority research area to reduce the total energy cost of carbon capture and sequestration technologies in coal-fired power plants. Efficient CO 2 removal from flue gases by adsorption systems requires the design of novel sorbents capable of capturing, concentrating, and recovering CO 2 on a cost-effective basis. This paper describes the preparation of an aminosilane-functionalized cellulosic polymer sorbent with enhanced CO 2 sorption capacity and promising performance for use in postcombustion carbon capture via rapid temperature-swing adsorption systems. The introduction of aminosilane functionalities onto the backbone of cellulose acetate was achieved by the anhydrous grafting of N-(2-aminoethyl)-3- aminoisobutyldimethylmethoxysilane. The dry sorption capacity of the modified cellulosic polymer reached 27 cc (STP) CO 2/cc sorbent (1.01 mmol/g sorbent) at 1 atm and 39 cc (STP) CO 2/cc sorbent (1.46 mmol/g sorbent) at 5 atm and 308 K. The amine loading achieved was 5.18 mmol amine(nitrogen)/g sorbent. Exposure to water vapor after the first dry sorption cycle increased the dry sorption capacity of the sorbent by 12% at 1 atm, suggesting its potential for rapid cyclic adsorption processes under humid feed conditions. The CO 2 sorbent was characterized in terms of chemical composition, density changes, molecular structure, thermal stability, and surface morphology. © 2011 American Chemical Society.

  13. Aminosilane-Functionalized Cellulosic Polymer for Increased Carbon Dioxide Sorption

    KAUST Repository

    Pacheco, Diana M.; Johnson, J.R.; Koros, William J.

    2012-01-01

    Improvement in the efficiency of CO 2 separation from flue gases is a high-priority research area to reduce the total energy cost of carbon capture and sequestration technologies in coal-fired power plants. Efficient CO 2 removal from flue gases by adsorption systems requires the design of novel sorbents capable of capturing, concentrating, and recovering CO 2 on a cost-effective basis. This paper describes the preparation of an aminosilane-functionalized cellulosic polymer sorbent with enhanced CO 2 sorption capacity and promising performance for use in postcombustion carbon capture via rapid temperature-swing adsorption systems. The introduction of aminosilane functionalities onto the backbone of cellulose acetate was achieved by the anhydrous grafting of N-(2-aminoethyl)-3- aminoisobutyldimethylmethoxysilane. The dry sorption capacity of the modified cellulosic polymer reached 27 cc (STP) CO 2/cc sorbent (1.01 mmol/g sorbent) at 1 atm and 39 cc (STP) CO 2/cc sorbent (1.46 mmol/g sorbent) at 5 atm and 308 K. The amine loading achieved was 5.18 mmol amine(nitrogen)/g sorbent. Exposure to water vapor after the first dry sorption cycle increased the dry sorption capacity of the sorbent by 12% at 1 atm, suggesting its potential for rapid cyclic adsorption processes under humid feed conditions. The CO 2 sorbent was characterized in terms of chemical composition, density changes, molecular structure, thermal stability, and surface morphology. © 2011 American Chemical Society.

  14. Strontium sorption on Savannah River Plant soils

    International Nuclear Information System (INIS)

    Hoeffner, S.L.

    1984-12-01

    A laboratory study of strontium-85 sorption was conducted using Savannah River Plant soil and groundwater from the low-level waste burial ground. Systematic variation of soil and water composition indicates that strontium sorption is most strongly a function of pH. Changes in clay content and in K + , Ca 2+ , or Mg 2+ concentrations influence strontium sorption indirectly through the slight pH changes which result. The ions Na + , Cl - , and NO 3 - have no effect. Ferrous ion, added to groundwater to simulate the conditions of water at the bottom of waste trenches, did not account for low strontium sorption observed with some trench waters

  15. Thermodynamic design of 10 kW Brayton cryocooler for HTS cable

    Science.gov (United States)

    Chang, Ho-Myung; Park, C. W.; Yang, H. S.; Sohn, Song Ho; Lim, Ji Hyun; Oh, S. R.; Hwang, Si Dole

    2012-06-01

    Thermodynamic design of Brayton cryocooler is presented as part of an ongoing governmental project in Korea, aiming at 1 km HTS power cable in the transmission grid. The refrigeration requirement is 10 kW for continuously sub-cooling liquid nitrogen from 72 K to 65 K. An ideal Brayton cycle for this application is first investigated to examine the fundamental features. Then a practical cycle for a Brayton cryocooler is designed, taking into account the performance of compressor, expander, and heat exchangers. Commercial software (Aspen HYSYS) is used for simulating the refrigeration cycle with real fluid properties of refrigerant. Helium is selected as a refrigerant, as it is superior to neon in thermodynamic efficiency. The operating pressure and flow rate of refrigerant are decided with a constraint to avoid the freezing of liquid nitrogen

  16. Calorimetric thermal-vacuum performance characterization of the BAe 80K space cryocooler

    International Nuclear Information System (INIS)

    Kotsubo, V.Y.; Johnson, D.L.; Ross, R.G. Jr.

    1992-01-01

    This paper on a comprehensive characterization program which is underway at JPL to generate test data on long-life, miniature Stirling-cycle cryocoolers for space application. The key focus of this paper is on the thermal performance of the British Aerospace (BAe) 80K split-Stirling-cycle cryocooler as measured in a unique calorimetric thermal-vacuum test chamber that accurately simulates the heat-transfer interfaces of space. Two separate cooling fluid loops provide precis individual control of the compressor and displacer heatsink temperatures. In addition, heatflow transducers enable calorimetric measurements of the heat rejected separately by the compressor and displacer. Cooler thermal performance has been mapped for coldtip temperatures ranging from below 45 K to above 150 K, for heat-sink temperatures ranging from 280 K to 320 K, and for a wide variety of operational variables including compressor-displacer phase, compressor-displacer stoke, drive frequency, and piston-displacer dc offset

  17. Comparative study on sorption of radiocobalt to montmorillonite and its Al-pillared and cross-linked samples. Effect of pH, ionic strength and fulvic acid

    International Nuclear Information System (INIS)

    Yu, S.; Cheng, J.; Chen, C.; Wang, X.

    2007-01-01

    Effects of pH, ionic strength and fulvic acid on sorption of radiocobalt on montmorillonite and its Al-pillared and cross-linked samples were studied using batch technique. The results indicate that the sorption of cobalt is strongly dependent on pH values and independent of ionic strength. Fulvic acid enhances the sorption of cobalt slightly at low pH, but has no influence at high pH values. Surface complexation is considered the main mechanism of cobalt sorption to montmorillonite. The sequences of FA/Co 2+ additions to the system did not affect cobalt sorption. (author)

  18. Effects of humic acid and heavy metals on the sorption of polar and apolar organic pollutants onto biochars

    International Nuclear Information System (INIS)

    Wang, Fei; Sun, Hongwen; Ren, Xinhao; Liu, Yarui; Zhu, Hongkai; Zhang, Peng; Ren, Chao

    2017-01-01

    The effects of humic acid (HA) and heavy metals (Cu 2+ and Ag + ) on the sorption of polar and apolar organic pollutants onto biochars that were produced at temperatures of 200 °C (BC200) and 700 °C (BC700) were studied. Due to the plentiful polar functional groups on BC200, cationic propranolol exhibited higher levels of sorption than naphthalene on BC200 while naphthalene and propranolol showed similar sorption capacities on BC700. HA changed the characteristics of biochars and generally inhibited the sorption of target organic pollutants on biochars; however, enhancement occurred in some cases depending on the pollutants involved and their concentrations, biochars used and the addition sequences and concentrations of HA. On BC200, HA modifications mainly influenced sorption by decreasing its polarity and increasing its aromaticity, while on BC700, the surface area and pore volume greatly decreased due to the pore-blocking effects of HA. Residue dissolved HA in solution may also contribute to sorption inhibition. Complexation between polar functional groups on BC200 and heavy metals slightly enhanced the sorption of neutral naphthalene and significantly enhanced that of anionic 4-nitro-1-naphtol, while limited the sorption of cationic propranolol. Heavy metals together with their associated water molecules decreased the sorption of target chemicals on BC700 via pore-filling or pore-mouth-covering. Inhibition of heavy metals for 4-nitro-1-naphthol was found to be the weakest due to the bridge effects of heavy metals between 4-nitro-1-naphtol and BC700. The higher polarizability of Ag + led to the increase of its sorption on biochars in the presence of organic aromatic pollutants. The results of the present study shed light on the sorption mechanisms of bi-solute systems and enable us to select suitable biochar sorbents when chemicals co-exist. - Highlights: • Polar functional groups on low-temperature biochar enhanced propranolol sorption. • Humic acid

  19. In-situ subaqueous capping of mercury-contaminated sediments in a fresh-water aquatic system, Part II-evaluation of sorption materials

    International Nuclear Information System (INIS)

    Randall, Paul M.; Yates, Brian J.; Lal, Vivek; Darlington, Ramona; Fimmen, Ryan

    2013-01-01

    The function and longevity of traditional, passive, isolation caps can be augmented through the use of more chemically active capping materials which have higher sorptive capacities, ideally rendering metals non-bioavailable. In the case of Hg, active caps also mitigate the rate and extent of methylation. This research examined low cost, readily available, capping materials for their ability to sequester Hg and MeHg. Furthermore, selected capping materials were evaluated to inhibit the methylation of Hg in an incubation study as well as the capacity of a selected capping material to inhibit translocation of Hg and MeHg with respect to ebullition-facilitated contaminant transport in a column study. Results indicated that bauxite had a better capacity for mercury sorption than the other test materials. However, bauxite as well as soil capping materials did not decrease methylation to a significant extent. Materials with larger surface areas, higher organic matter and acid volatile sulfide (AVS) content displayed a larger partitioning coefficient. In the incubation experiments, the presence of a carbon source (lactate), electron acceptor (sulfate) and the appropriate strains of SRB provided the necessary conditions for Hg methylation to occur. The column study showed effectiveness in sequestering Hg and MeHg and retarding transport to the overlying water column; however, disturbances to the soil capping material resulting from gas ebullition negated its effectiveness

  20. In-situ subaqueous capping of mercury-contaminated sediments in a fresh-water aquatic system, Part II-evaluation of sorption materials

    Energy Technology Data Exchange (ETDEWEB)

    Randall, Paul M., E-mail: randall.paul@epa.gov [U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 W. Martin Luther King Drive, Cincinnati, OH 45268 (United States); Yates, Brian J.; Lal, Vivek; Darlington, Ramona [Battelle, 505 King Avenue, Columbus, OH 43201 (United States); Fimmen, Ryan [Geosyntec Consultants, 150 E. Wilson Bridge Road, Suite 232, Worthington, OH 43085 (United States)

    2013-08-15

    The function and longevity of traditional, passive, isolation caps can be augmented through the use of more chemically active capping materials which have higher sorptive capacities, ideally rendering metals non-bioavailable. In the case of Hg, active caps also mitigate the rate and extent of methylation. This research examined low cost, readily available, capping materials for their ability to sequester Hg and MeHg. Furthermore, selected capping materials were evaluated to inhibit the methylation of Hg in an incubation study as well as the capacity of a selected capping material to inhibit translocation of Hg and MeHg with respect to ebullition-facilitated contaminant transport in a column study. Results indicated that bauxite had a better capacity for mercury sorption than the other test materials. However, bauxite as well as soil capping materials did not decrease methylation to a significant extent. Materials with larger surface areas, higher organic matter and acid volatile sulfide (AVS) content displayed a larger partitioning coefficient. In the incubation experiments, the presence of a carbon source (lactate), electron acceptor (sulfate) and the appropriate strains of SRB provided the necessary conditions for Hg methylation to occur. The column study showed effectiveness in sequestering Hg and MeHg and retarding transport to the overlying water column; however, disturbances to the soil capping material resulting from gas ebullition negated its effectiveness.

  1. Thermal analysis of the cryocooled superconducting magnet for the liquid helium-free hybrid magnet

    International Nuclear Information System (INIS)

    Ishizuka, Masayuki; Hamajima, Takataro; Itou, Tomoyuki; Sakuraba, Junji; Nishijima, Gen; Awaji, Satoshi; Watanabe, Kazuo

    2010-01-01

    The liquid helium-free hybrid magnet, which consists of an outer large bore cryocooled superconducting magnet and an inner water-cooled resistive magnet, was developed for magneto-science in high fields. The characteristic features of the cryogen-free outsert superconducting magnet are described in detail in this paper. The superconducting magnet cooled by Gifford-McMahon cryocoolers, which has a 360 mm room temperature bore in diameter, was designed to generate high magnetic fields up to 10 T. The hybrid magnet has generated the magnetic field of 27.5 T by combining 8.5 T generation of the cryogen-free superconducting magnet with 19 T generation of the water-cooled resistive magnet. The superconducting magnet was composed of inner Nb 3 Sn coils and outer NbTi coils. In particular, inner Nb 3 Sn coils were wound using high-strength CuNi-NbTi/Nb 3 Sn wires in consideration of large hoop stress. Although the cryocooled outsert superconducting magnet achieved 9.5 T, we found that the outsert magnet has a thermal problem to generate the designed maximum field of 10 T in the hybrid magnet operation. This problem is associated with unexpected AC losses in Nb 3 Sn wires.

  2. Linear Resonance Compressor for Stirling-Type Cryocoolers Activated by Piezoelectric Stack-Type Elements

    International Nuclear Information System (INIS)

    Sobol, S; Grossman, G

    2015-01-01

    A novel type of a PZT- based compressor operating at mechanical resonance, suitable for pneumatically-driven Stirling-type cryocoolers was developed theoretically and built practically during this research. A resonance operation at relatively low frequency was achieved by incorporating the piezo ceramics into the moving part, and by reducing the effective piezo stiffness using hydraulic amplification. The detailed concept, analytical model and the test results of the preliminary prototype were reported earlier and presented at ICC17 [2]. A fine agreement between the simulations and experiments spurred development of the current actual compressor designed to drive a miniature Pulse Tube cryocooler, particularly our MTSa model, which operates at 103 Hz and requires an average PV power of 11 W, filling pressure of 40 Bar and a pressure ratio of 1.3. The paper concentrates on design aspects and optimization of the governing parameters. The small stroke to diameter ratio (about 1:10) allows for the use of a composite diaphragm instead of a clearance-seal piston. The motivation is to create an adequate separation between the working fluid and the buffer gas of the compressor, thus preventing possible contamination in the cryocooler. Providing efficiency and power density similar to those of conventional linear compressors, the piezo compressor may serve as a good alternative for cryogenic applications requiring extreme reliability and absence of magnetic field interference. (paper)

  3. Determination of Chlorinated Solvent Sorption by Porous Material-Application to Trichloroethene Vapor on Cement Mortar.

    Science.gov (United States)

    Musielak, Marion; Brusseau, Mark L; Marcoux, Manuel; Morrison, Candice; Quintard, Michel

    2014-08-01

    Experiments have been performed to investigate the sorption of trichloroethene (TCE) vapor by concrete material or, more specifically, the cement mortar component. Gas-flow experiments were conducted using columns packed with small pieces of cement mortar obtained from the grinding of typical concrete material. Transport and retardation of TCE at high vapor concentrations (500 mg L -1 ) was compared to that of a non-reactive gas tracer (Sulfur Hexafluoride, SF6). The results show a large magnitude of retardation (retardation factor = 23) and sorption (sorption coefficient = 10.6 cm 3 g -1 ) for TCE, compared to negligible sorption for SF6. This magnitude of sorption obtained with pollutant vapor is much bigger than the one obtained for aqueous-flow experiments conducted for water-saturated systems. The considerable sorption exhibited for TCE under vapor-flow conditions is attributed to some combination of accumulation at the air-water interface and vapor-phase adsorption, both of which are anticipated to be significant for this system given the large surface area associated with the cement mortar. Transport of both SF6 and TCE was simulated successfully with a two-region physical non-equilibrium model, consistent with the dual-medium structure of the crushed cement mortar. This work emphasizes the importance of taking into account sorption phenomena when modeling transport of volatile organic compounds through concrete material, especially in regard to assessing vapor intrusion.

  4. A study of sorption of pertechnetate anion on chitosan

    International Nuclear Information System (INIS)

    Pivarciova, L.; Rosskopfova, O.; Rajec, P.; Galambos, M.

    2015-01-01

    Chitosan is one of the natural materials of biological origin. The sorption of pertechnetate anions from aqueous solutions on chitosan was studied in a batch system. This work was aimed to study influence of the contact time, effect of pH and effect of different ions on sorption of pertechnetate anions on chitosan. This sorbent was characterized by BET-surface area and potentiometric titration. The point of zero charge (pH pzc ) was at pH=7.15. The highest percentage of technetium sorption on chitosan was near pH 3. The adsorption capacity of chitosan decreased with increase in pH value above 3. In the initial pH range of 4-10, final pHs are the same. The selectivity of chitosan for these cations with concentration above 1·10 -3 mol·dm -3 was in the order Na + > Ca 2+ > Fe 3+ > Fe 2+ . The competition effect of (SO 4 ) 2- towards TcO 4 - sorption was stronger than the competition effect (ClO 4 ) - of ions. (authors)

  5. Uranium(VI) sorption on iron oxides in Hanford Site sediment: Application of a surface complexation model

    International Nuclear Information System (INIS)

    Um, Wooyong; Serne, R. Jeffrey; Brown, Christopher F.; Rod, Kenton A.

    2008-01-01

    Sorption of U(VI) on Hanford fine sand (HFS) with varying Fe-oxide (especially ferrihydrite) contents showed that U(VI) sorption increased with the incremental addition of synthetic ferrihydrite into HFS, consistent with ferrihydrite being one of the most reactive U(VI) sorbents present in natural sediments. Surface complexation model (SCM) calculations for U(VI) sorption, using only U(VI) surface-reaction constants obtained from U(VI) sorption data on freshly synthesized ferrihydrite at different pHs, were similar to the measured U(VI) sorption results on pure synthetic ferrihydrite and on HFS with high contents of ferrihydrite (5 wt%) added. However, the SCM prediction using only U(VI) sorption reactions and constants for synthetic ferrihydrite overestimated U(VI) sorption on the natural HFS or HFS with addition of low amounts of added ferrihydrite (1 wt% added). Over-predicted U(VI) sorption was attributed to reduced reactivity of natural ferrihydrite present in Hanford Site sediments, compared to freshly prepared synthetic ferrihydrite. Even though the SCM general composite (GC) approach is considered to be a semi-quantitative estimation technique for contaminant sorption, which requires systematic experimental data on the sorbent-sorbate system being studied to obtain credible SCM parameters, the general composite SCM model was still found to be a useful technique for describing U(VI) sorption on natural sediments. Based on U(VI) batch sorption results, two simple U(VI) monodentate surface species, SO U O 2 HCO 3 and SO U O 2 OH on ferrihydrite and phyllosillicate in HFS, respectively, can be successfully used to describe U(VI) sorption onto Hanford Site sediment contacting varying geochemical solutions

  6. New sorption-reagent materials for decontamination of liquid radioactive waste

    International Nuclear Information System (INIS)

    Avramenko, V.A.; Golikov, A.P.; Zheleznov, V.V.; Kaplun, E.V.; Marinin, D.V.; Sokolnitskaya, T.A.

    2001-01-01

    Full text: Use of selective sorbents in liquid radioactive waste (LRW) management is widely spread in the field of nuclear power objects liquid waste decontamination, since the main objective there is to remove long-lived radionuclides of the nuclear cycle. The latter include, first of all, cesium-137, strontium-90, cobalt-60 and a number of α-irradiators. In this case LRW composition for most of the nuclear power objects is rather simple, except acidic deactivation solutions. At the same time, liquid radioactive wastes of different research centers have a variable chemical and radiochemical composition depending on objectives and tasks of a given center research activities. As a result, application of sorption technologies in such waste decontamination determines special requirements to these sorbents selectivity: a wide spectrum of radionuclides that can be removed and fairly high selectivity enabling to remove radionuclides from solutions of complex chemical composition (containing surfactants, complexing agents etc.). This paper is concerned with studying properties of new materials selective to different radionuclides. These materials are capable to interact with solution components whether already contained in the waste or deliberately added into resulting solution. Such sorption-reagent materials combine universal character of co-precipitation methods with simplicity of sorption methods. In this work we studied sorption-reagent inorganic ion-exchange materials interacting with sulfate-, carbonate-, oxalate-, sulfide-, and permanganate-ions. Insoluble compounds formed as a result of this interaction increase tens- and hundreds-fold the sorption selectivity of different radionuclides - strontium, cobalt, mercury, iron, and manganese as compared to conventional ion-exchange system. By means of X-ray phase analysis, IR-spectroscopy, chemical and radiochemical analysis, we have studied the mechanism of radionuclide sorption on different sorption

  7. Sorption of radionuclides on inorganic sorbents

    International Nuclear Information System (INIS)

    Rajec, P.; Matel, L.

    1995-01-01

    The sorption of cesium, strontium, plutonium and americium from water solution on natural zeolite, clay minerals, synthetic zeolites and ferrocyanides in silica gel matrix was studied. The same experiments but with synthetic zeolites irradiated by the dose 100 kGy proved no change in sorption properties. 1 tab., 4 refs

  8. Nitrate Sorption in an Agricultural Soil Profile

    Directory of Open Access Journals (Sweden)

    Wissem Hamdi

    2013-01-01

    Full Text Available Increasing concentrations of in surface water and groundwater can cause ecological and public health effects and has come under increased scrutiny by both environmental scientists and regulatory agencies. For many regions though, including the Sahel of Tunisia, little is known about the sorption capacity of soils. In this project we measured sorption by a profile of an iso-humic soil from Chott Meriem, Tunisia. Soil samples were collected from four soil depths (0–25, 25–60, 60–90, and 90–120 cm on 1 June 2011, and their sorption capacity was determined using batch experiments under laboratory conditions. The effects of contact time, the initial concentration, and the soil-solution ratio on sorption were investigated. In general, the results suggested that was weakly retained by the Chott Meriem soil profile. The quantity of sorption increased with depth, contact time, initial concentration, and soil-solution ratios. To evaluate the sorption capacities of the soil samples at concentrations ranging between 25 and 150 mg L−1 experimental data were fitted to both Freundlich and Langmuir isotherm sorption models. The results indicated that Freundlich model was better for describing sorption in this soil profile.

  9. Thermal analysis of the conduction cooling system for HTS SMES system of 600 kJ class

    International Nuclear Information System (INIS)

    Hong, Yong Ju; Yeom, Han Kil; Park, Seong Je; Kim, Hyo Bong; Koh, Deuk Yong

    2007-01-01

    SMES systems need cryogenic cooling systems. Conduction cooling system has more effective, compact structure than cryogen. In general, 2 stage GM cryocoolers are used for conduction cooling of HTS SMES system. 1st stages of cryocoolers are used for the cooling of current leads and radiation shields, and 2nd stages of cryocoolers for HTS coil. For the effective conduction cooling of the HTS SMES system, the temperature difference between the cryocooler and HTS coil should be minimized. In this paper, a cryogenic conduction cooling system for HTS SMES is analyzed to evaluate the performance of the cooling system. The analysis is carried out for the steady state with the heat generation of the HTS coil and effects of the thermal contact resistance. The results show the effects of the heat generation and thermal contact resistance on the temperature distribution

  10. Sorption of organic water pollutants on dead vegetable biomass; Sorption organischer Wasserschadstoffe an abgestorbene pflanzliche Biomasse

    Energy Technology Data Exchange (ETDEWEB)

    Kraeuter, A.

    2001-03-01

    Hemp-derived biological sorption agents were produced, and their physical, chemical and sorptive characteristics were tested in batch and filter tests. The experiments were accompanied by model calculations. In the natural state, the sorption agents had a kation exchange capacity of 0.1-0.3 mmol/g, modified sorption agents had about 2 mmol/g. Kationized hemp had values of 0.34 mmol/g and thermally modified hemp absorption agents absorbed more than 1.2 mmol/g of dichlorophenol. In the case of a liquid effluent from a textile dyeing plant, only a discoloration effect was achieved. The absorption agents can be regenerated, combusted or composted after use. [German] Im Rahmen dieser Arbeit wurden naturbelassene und modifizierte Billig-Biosorbentien aus Hanfschaeben zur Entfernung organischer Schadstoffe aus Waessern hergestellt und ihre physikalischen, chemischen und sorptiven Eigenschaften in Batch- und Filterversuchen untersucht. Wegen der Komplexheit des Systems ''Biosorption organischer Wasserschadstoffe'' wurden die ermittelten Sorptionsisothermen mit den Ansaetzen nach Langmuir und Freundlich beschrieben. Die Sorptionskinetik und das Durchbruchsverhalten wurde ebenfalls mit einfachen Ansaetzen modelliert. Naturbelassene Hanfschaeben erreichten Kationenaustauschkapazitaeten von 0,1-0,3 mmol/g, entsprechend modifizierte Hanfschaeben ca. 2 mmol/g. Kationisierte Hanfschaeben dagegen erreichten Anionenaustauschkapazitaeten von 0,34 mmol/g und thermisch modifizierte Hanfschaeben sorbierten bis ueber 1,2 mmol/g Dichlorphenol. Bei der Behandlung eines Abwassers aus einer Textilfaerberei beschraenkte sich die Reinigungsleistung der hergestellten Biosorbentien auf eine Entfaerbung. Nach Schadstoffbeladung koennen die Hanfschaeben regeneriert, thermisch verwertet oder kompostiert werden. (orig.)

  11. Surface complexation modeling of zinc sorption onto ferrihydrite.

    Science.gov (United States)

    Dyer, James A; Trivedi, Paras; Scrivner, Noel C; Sparks, Donald L

    2004-02-01

    A previous study involving lead(II) [Pb(II)] sorption onto ferrihydrite over a wide range of conditions highlighted the advantages of combining molecular- and macroscopic-scale investigations with surface complexation modeling to predict Pb(II) speciation and partitioning in aqueous systems. In this work, an extensive collection of new macroscopic and spectroscopic data was used to assess the ability of the modified triple-layer model (TLM) to predict single-solute zinc(II) [Zn(II)] sorption onto 2-line ferrihydrite in NaNO(3) solutions as a function of pH, ionic strength, and concentration. Regression of constant-pH isotherm data, together with potentiometric titration and pH edge data, was a much more rigorous test of the modified TLM than fitting pH edge data alone. When coupled with valuable input from spectroscopic analyses, good fits of the isotherm data were obtained with a one-species, one-Zn-sorption-site model using the bidentate-mononuclear surface complex, (triple bond FeO)(2)Zn; however, surprisingly, both the density of Zn(II) sorption sites and the value of the best-fit equilibrium "constant" for the bidentate-mononuclear complex had to be adjusted with pH to adequately fit the isotherm data. Although spectroscopy provided some evidence for multinuclear surface complex formation at surface loadings approaching site saturation at pH >/=6.5, the assumption of a bidentate-mononuclear surface complex provided acceptable fits of the sorption data over the entire range of conditions studied. Regressing edge data in the absence of isotherm and spectroscopic data resulted in a fair number of surface-species/site-type combinations that provided acceptable fits of the edge data, but unacceptable fits of the isotherm data. A linear relationship between logK((triple bond FeO)2Zn) and pH was found, given by logK((triple bond FeO)2Znat1g/l)=2.058 (pH)-6.131. In addition, a surface activity coefficient term was introduced to the model to reduce the ionic strength

  12. Sorption of mercury on chemically synthesized polyaniline

    International Nuclear Information System (INIS)

    Remya Devi, P.S.; Verma, R.; Sudersanan, M.

    2006-01-01

    Sorption of inorganic mercury (Hg 2+ ) and methyl mercury, on chemically synthesized polyaniline, in 0.1-10N HCl solutions has been studied. Hg 2+ is strongly sorbed at low acidities and the extent of sorption decreases with increase in acidity. The sorption of methyl mercury is very low in the HCl concentration range studied. Sorption of Hg 2+ on polyaniline in 0.1-10N LiCl and H 2 SO 4 solutions has also been studied. The analysis of the data indicates that the sorption of Hg 2+ depends on the degree of protonation of polyaniline and the nature of mercury(II) chloride complexes in solution. X-ray photoelectron spectroscopy analysis (XPS) of polyaniline sorbed with mercury show that mercury is bound as Hg 2+ . Sorbed mercury is quantitatively eluted from polyaniline with 0.5N HNO 3 . Polyaniline can be used for separation and pre-concentration of inorganic mercury from aqueous samples. (author)

  13. Phenanthrene sorption on biochar-amended soils

    DEFF Research Database (Denmark)

    Kahawaththa Gamage, Inoka Damayanthi Kumari; Moldrup, Per; Paradelo Pérez, Marcos

    2014-01-01

    on their influences on the sorption of environmental contaminants. In a field-based study at two experimental sites in Denmark, we investigated the effect of birch wood-derived biochar (Skogans kol) on the sorption of phenanthrene in soils with different properties. The soil sorption coefficient, Kd (L kg-1......), of phenanthrene was measured on sandy loam and loamy sand soils which have received from zero up to 100 t ha-1 of biochar. Results show that birch wood biochar had a higher Kd compared to soils. Furthermore, the application of birch wood biochar enhanced the sorption of phenanthrene in agricultural soils...... carbon, while it negatively correlated with clay content. The results also revealed that biochar-mineral interactions play an important role in the sorption of phenanthrene in biochar-amended soil....

  14. Cobalt sorption onto Savannah River Plant soils

    International Nuclear Information System (INIS)

    Hoeffner, S.L.

    1985-06-01

    A laboratory study of cobalt-60 sorption was conducted using Savannah River Plant soil and groundwater from the low-level waste burial ground. Systematic variation of soil and water composition indicates that cobalt sorption is most strongly a function of pH. Over a pH range of 2 to 9, the distribution coefficient ranged from 2 to more than 10,000 mL/g. Changes in clay content and in K + , Ca 2+ , or Mg 2+ concentrations influence cobalt sorption indirectly through the slight pH changes which result. The ions Na + , Cl - , and NO 3 - have no effect on cobalt sorption. Ferrous ion, added to groundwater to simulate the condition of water at the bottom of the waste trenches, accounts for part of the decrease in cobalt sorption observed with trench waters. 17 refs., 3 figs., 4 tabs

  15. High-resolution X-ray crystal structure of bovine H-protein using the high-pressure cryocooling method.

    Science.gov (United States)

    Higashiura, Akifumi; Ohta, Kazunori; Masaki, Mika; Sato, Masaru; Inaka, Koji; Tanaka, Hiroaki; Nakagawa, Atsushi

    2013-11-01

    Recently, many technical improvements in macromolecular X-ray crystallography have increased the number of structures deposited in the Protein Data Bank and improved the resolution limit of protein structures. Almost all high-resolution structures have been determined using a synchrotron radiation source in conjunction with cryocooling techniques, which are required in order to minimize radiation damage. However, optimization of cryoprotectant conditions is a time-consuming and difficult step. To overcome this problem, the high-pressure cryocooling method was developed (Kim et al., 2005) and successfully applied to many protein-structure analyses. In this report, using the high-pressure cryocooling method, the X-ray crystal structure of bovine H-protein was determined at 0.86 Å resolution. Structural comparisons between high- and ambient-pressure cryocooled crystals at ultra-high resolution illustrate the versatility of this technique. This is the first ultra-high-resolution X-ray structure obtained using the high-pressure cryocooling method.

  16. A study on the uranium sorption properties of a domestic granite

    Energy Technology Data Exchange (ETDEWEB)

    Baik, Min Hoon; Kang, Mun Ja; Keum, Dong Kwon; Hahn, Pil Soo

    2003-01-01

    In this report, we selected a domestic granite rock as a studying medium. Granite rock is considered as candidate rock for a high-level radioactive waste repository site and as a representative system of the composite mineral systems. We performed sorption experiments for crushed particles, intact rock surfaces, and natural fracture surfaces of the domestic granite rock and investigated the effects of important geochemical parameters such as pH, ionic strength, carbonate concentration. Fracture surfaces showed higher sorption capacities than intact rock surfaces due to the higher content of secondary minerals and the amount of sorbed uranium was greatly dependent on pH, surface types, and carbonate concentration but little on ionic strength. Besides, we tried to investigate the nuclide sorption behaviors of composite mineral systems in terms of mineralogy in order to evaluate the contribution of constituent minerals and to analyze the sorption properties using sequential chemical extraction and XRD, and EPMA methods. It was found that one dominant mineral(mica in case of intact rock surfaces and chlorite in case of fracture surfaces) controls the uranium sorption and nuclide sorption behavior of composite mineral systems are quite different with that of single mineral systems.

  17. Design And Tests Of A Superconducting Magnet With A Cryocooler For The Ion Source Decris-sc

    CERN Document Server

    Datskov, V I; Bekhterev, V V; Bogomolov, S L; Bondarenko, P G; Dmitriev, S N; Drobin, V M; Efremov, A A; Iakovlev, B I; Leporis, M; Malinowski, H; Nikiforov, S A; Paschenko, S V; Seleznev, V V; Shishov, Yu A; Tsvineva, G P; Yazvitsky, N Yu

    2004-01-01

    A superconducting magnet system (SMS) for the multicharged ion source DECRIS-SC was designed and manufactured at the Joint Institute for Nuclear Research. Successful tests of the SMS were conducted in late 2003 - early 2004. The peculiarities of this system are stipulated by using of a cryocooler 1 W in power for the cryostabilization of the magnet, and also by a special configuration of the magnetic field demanded for the source of ions. Four coils ensure induction of a magnetic field on the axes of the source of up to 3T (the mirror ratio of ~6) which considerably extends possibilities of the ion source from the point of view of producing intense highly charged ion beams. The problem of compensating large forces of interaction between the coils and surrounding iron yoke in this magnet has been successfully solved, and a reliable suspension of the magnet in a cryostat realized. For compounding of the windings working in vacuum at indirect cryostabilization prepreg is used. There has been applied a new techno...

  18. Prediction of metal sorption in soils

    International Nuclear Information System (INIS)

    Westrich, Henry R.; Anderson, Harold L. Jr.; Arthur, Sara E.; Brady, Patrick V.; Cygan, Randall T.; Liang, Jianjie; Zhang, Pengchu; Yee, N.

    2000-01-01

    Radionuclide transport in soils and groundwaters is routinely calculated in performance assessment (PA) codes using simplified conceptual models for radionuclide sorption, such as the K D approach for linear and reversible sorption. Model inaccuracies are typically addressed by adding layers of conservativeness (e.g., very low K D 's), and often result in failed transport predictions or substantial increases in site cleanup costs. Realistic assessments of radionuclide transport over a wide range of environmental conditions can proceed only from accurate, mechanistic models of the sorption process. They have focused on the sorption mechanisms and partition coefficients for Cs + , Sr 2+ and Ba 2+ (analogue for Ra 2+ ) onto iron oxides and clay minerals using an integrated approach that includes computer simulations, sorption/desorption measurements, and synchrotron analyses of metal sorbed substrates under geochemically realistic conditions. Sorption of Ba 2+ and Sr 2+ onto smectite is strong, pH-independent, and fully reversible, suggesting that cation exchange at the interlayer basal sites controls the sorption process. Sr 2+ sorbs weakly onto geothite and quartz, and is pH-dependent. Sr 2+ sorption onto a mixture of smectite and goethite, however, is pH- and concentration dependent. The adsorption capacity of montmorillonite is higher than that of goethite, which may be attributed to the high specific surface area and reaction site density of clays. The presence of goethite also appears to control the extent of metal desorption. In-situ, extended X-ray absorption fine structure (EXAFS) spectroscopic measurements for montmorillonite and goethite show that the first shell of adsorbed Ba 2+ is coordinated by 6 oxygens. The second adsorption shell, however, varies with the mineral surface coverage of adsorbed Ba 2+ and the mineral substrate. This suggests that Ba 2+ adsorption on mineral surfaces involves more than one mechanism and that the stability of sorbed

  19. Sorption of uranyl ions on hydrous oxides

    International Nuclear Information System (INIS)

    Gupta, A.R.; Venkataramani, B.

    1988-01-01

    Sorption of uranyl ions on hydrous titanium oxide (HTiO), magnetite (MAG), and hydrous thorium oxide (HThO) has been studied as a function of pH. Hydrous oxides have been characterized by their pH-titration curves, intrinsic dissociation constants (pK ai * ) and point of zero charge (pH pzc ). The fraction of protonated surface hydroxyl groups as well as the surface pH (pH surf ) as a function of solution pH have been computed. The distribution of various hydrolyzed species of uranyl ions with solution pH have been compared with uranyl sorption isotherm on these oxides. Sorption edge in all the cases occurs when free hydroxyl groups are available on the surface and pH surf is sufficiently high to favor the formation of dimer-like species on the surface. A new model for the sorption process, called surface hydrolysis model, which explains these and other features of uranyl sorption on hydrous oxides has been proposed. The model visualizes the sorption process as linking of uranyl ions with two adjacent free surface hydroxyl groups without deprotonation (provided the surface pH is high for the hydrolysis of uranyl ions) and formation of dimer-like structures on the surface. The new model has been successfully applied to the present and other available data on uranyl ion sorption on hydrous oxides. (author)

  20. Sorption equilibria of ethanol on cork.

    Science.gov (United States)

    Lequin, Sonia; Chassagne, David; Karbowiak, Thomas; Bellat, Jean-Pierre

    2013-06-05

    We report here for the first time a thermodynamic study of gaseous ethanol sorption on raw cork powder and plate. Our study aims at a better understanding of the reactivity of this material when used as a stopper under enological conditions, thus in close contact with a hydroethanolic solution, wine. Sorption−desorption isotherms were accurately measured by thermogravimetry at 298 K in a large range of relative pressures. Sorption enthalpies were determined by calorimetry as a function of loading. Sorption−desorption isotherms exhibit a hysteresis loop probably due to the swelling of the material and the absorption of ethanol. Surprisingly, the sorption enthalpy of ethanol becomes lower than the liquefaction enthalpy as the filling increases. This result could be attributed to the swelling of the material, which would generate endothermic effects. Sorption of SO₂ on cork containing ethanol was also studied. When the ethanol content in cork is 2 wt %, the amount of SO₂ sorbed is divided by 2. Thus, ethanol does not enhance the sorption rate for SO₂ but, on the contrary, decreases the SO₂ sorption activity onto cork, probably because of competitive sorption mechanisms.

  1. Sorption of streptococcus faecium to glass

    International Nuclear Information System (INIS)

    Oerstavik, D.

    1977-01-01

    A method has been developed by which to study the sorption of Streptococcus faecium to soda-lime cover glasses. Conditions were chosen to minimize the influence on sorption of bacterial polymer production, passive sorption being studied rather than attachment mediated by metabolic activities. Sorption of S. faecium increased with increasing temperature (to 50degC), time, and cell concentration, but equilibrium apparently was not reached even after incubation for 8 hours or at a cell concentration of 3 x 10 10 per ml. Sorption increased with solute molarity up to 0.1 M concentration of NaCl and KCl, indicating an effect of the electrical double layers on the apposition of cells to the glass surface. Desorption of bacteria could be obtained after multiple washings of the glasses in buffer or by the action of Tween 80, but not if sorbed bacteria were left in distilled water, various salt solutions, urea, or in suspensions of unlabelled bacteria. It was concluded that sorption occurred as a result of chemical interactions between the glass and the cell surface. Tween 80 at a concentration of 1 per cent inhibited sorption to 26 per cent of buffer controls, 2 M urea was less effective, and 1 M NaCl was without effect. It is suggested that hydrophobic interactions may be of importance in the binding of S. faecium to glass. (author)

  2. Sorption of radionuclides from Pb-Bi melt. Report 1

    International Nuclear Information System (INIS)

    Konovalov, Eh.E.; Il'icheva, N.S.; Trifonova, O.E.

    2015-01-01

    Results of laboratory investigations of sorption and interfacial distribution of 54 Mn, 59 Fe, 60 Co, 106 Ru, 125 Sb, 137 Cs, 144 Ce, 154,155 Eu and 235,238 U radionuclides in the system Pb-Bi melt - steel surface are analyzed. It is shown that 106 Ru and 125 Sb are concentrated in Pb-Bi melt and other radionuclides with higher oxygen affinity are sorbed on oxide deposits on structural materials. Temperature dependences of sorption efficiency of radionuclides are studied. It is shown that there is sharp increase of this value for all radionuclides near the temperature range 350-400 deg C. Recommendations are given on the use of 106 Ru and 125 Sb as a reference for fuel element rupture detection system with radiometric monitoring of coolant melt samples and 137 Cs, 134 Cs, 134m Cs with radiometric monitoring of sorbing samples [ru

  3. Theoretical modeling of a gas clearance phase regulation mechanism for a pneumatically-driven split-Stirling-cycle cryocooler

    Science.gov (United States)

    Zhang, Cun-quan; Zhong, Cheng

    2015-03-01

    The concept of a new type of pneumatically-driven split-Stirling-cycle cryocooler with clearance-phase-adjustor is proposed. In this implementation, the gap between the phase-adjusting part and the cylinder of the spring chamber is used, instead of dry friction acting on the pneumatically-driven rod to control motion damping of the displacer and to adjust the phase difference between the compression piston and displacer. It has the advantages of easy damping adjustment, low cost, and simplified manufacturing and assembly. A theoretical model has been established to simulate its dynamic performance. The linear compressor is modeled under adiabatic conditions, and the displacement of the compression piston is experimentally rectified. The working characteristics of the compressor motor and the principal losses of cooling, including regenerator inefficiency loss, solid conduction loss, shuttle loss, pump loss and radiation loss, are taken into account. The displacer motion was modeled as a single-degree-of-freedom (SDOF) forced system. A set of governing equations can be solved numerically to simulate the cooler's performance. The simulation is useful for understanding the physical processes occurring in the cooler and for predicting the cooler's performance.

  4. Sorption-desorption of samarium in Febex bentonite

    International Nuclear Information System (INIS)

    Ramirez-Guinart, O.; Rigol, A.; Vidal, M.; Fernandez-Poyatos, P.; Alba, M. D.

    2012-01-01

    Document available in extended abstract form only. The chemical and physical nature of the clay is a key issue in the design of engineered barriers. The FEBEX bentonite is one of the clays candidates to be used in engineered barriers in deep geology repositories (DGR). Here, its performance was tested with respect to the sorption-desorption of samarium, which is a lanthanide that, besides being considered as a natural analogue of actinides, may also be present in high level radioactive waste in the form of the radioactive isotope 151 Sm. FEBEX bentonite was used in this study. This is a di-octahedral smectite, with isomorphic substitutions in tetrahedral and octahedral sheets. Its theoretical cation exchange capacity value is 1500 meq kg -1 . Sorption isotherms were obtained for Sm in the range of initial concentrations of 0.01 and 9 meq l -1 . Tests were carried out in deionized water and in a medium simulating the composition of interstitial water. Sorption tests were performed equilibrating 30 ml of the Sm solution with 0.2 g of clay. After a contact time of 24 hours, supernatants were decanted off after centrifugation. The quantification of the concentration of Sm in the initial and final solutions allowed us to quantify the Sm equilibrium concentration (C eq ), the fraction sorbed in the FEBEX bentonite (C sorb ) and to derive the sorption K d data. Desorption tests were applied to determine the desorption K d and the percentage of Sm reversibly sorbed. Desorption tests were performed with the bentonite residue from the sorption step, under the same experimental conditions, but without Sm. Powder X-ray diffractograms were obtained from 3 to 70 deg. 2θ with a step of 0.05 deg. and a counting time of 3 s. The crystalline phases were identified using the computer program X'Pert HighScore. The morphology of the samples was analyzed by SEM at 20 kV. An EDX system was fitted to the SEM equipment to perform chemical analyses of the samples using a Si/Li detector

  5. Determination of sorption mechanisms of radionuclides onto clay minerals using extended x-ray absorption fine structure (EXAFS) spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Daehn, R.; Scheidegger, A.; Baeyens, B.; Bradbury, M.H

    2001-03-01

    Much of the experimental work in the Waste Management Laboratory at PSI concentrates on trying to understand the processes and mechanisms which govern the release of safety-relevant radionuclides from waste matrices, and their transport through engineered barrier systems and the surrounding geosphere. For this reason, detailed sorption studies of radionuclides (Cs, Sr, Ni, Zn, Eu, Am, Th and Se) in clay and cement systems are being conducted. The sorption and modelling studies are combined with kinetic investigations and advanced spectroscopic and microscopic methods in order to understand the sorption mechanism on an atomic level. This approach is part of a new multidisciplinary research field called Molecular Environmental Science (MES). In this paper, a case study of Ni sorption on montmorillonite is presented to illustrate how EXAFS can be used successfully to better understand sorption processes. (author)

  6. Determination of sorption mechanisms of radionuclides onto clay minerals using extended x-ray absorption fine structure (EXAFS) spectroscopy

    International Nuclear Information System (INIS)

    Daehn, R.; Scheidegger, A.; Baeyens, B.; Bradbury, M.H.

    2001-01-01

    Much of the experimental work in the Waste Management Laboratory at PSI concentrates on trying to understand the processes and mechanisms which govern the release of safety-relevant radionuclides from waste matrices, and their transport through engineered barrier systems and the surrounding geosphere. For this reason, detailed sorption studies of radionuclides (Cs, Sr, Ni, Zn, Eu, Am, Th and Se) in clay and cement systems are being conducted. The sorption and modelling studies are combined with kinetic investigations and advanced spectroscopic and microscopic methods in order to understand the sorption mechanism on an atomic level. This approach is part of a new multidisciplinary research field called Molecular Environmental Science (MES). In this paper, a case study of Ni sorption on montmorillonite is presented to illustrate how EXAFS can be used successfully to better understand sorption processes. (author)

  7. SITE-94. Adaptation of mechanistic sorption models for performance assessment calculations

    International Nuclear Information System (INIS)

    Arthur, R.C.

    1996-10-01

    Sorption is considered in most predictive models of radionuclide transport in geologic systems. Most models simulate the effects of sorption in terms of empirical parameters, which however can be criticized because the data are only strictly valid under the experimental conditions at which they were measured. An alternative is to adopt a more mechanistic modeling framework based on recent advances in understanding the electrical properties of oxide mineral-water interfaces. It has recently been proposed that these 'surface-complexation' models may be directly applicable to natural systems. A possible approach for adapting mechanistic sorption models for use in performance assessments, using this 'surface-film' concept, is described in this report. Surface-acidity parameters in the Generalized Two-Layer surface complexation model are combined with surface-complexation constants for Np(V) sorption ob hydrous ferric oxide to derive an analytical model enabling direct calculation of corresponding intrinsic distribution coefficients as a function of pH, and Ca 2+ , Cl - , and HCO 3 - concentrations. The surface film concept is then used to calculate whole-rock distribution coefficients for Np(V) sorption by altered granitic rocks coexisting with a hypothetical, oxidized Aespoe groundwater. The calculated results suggest that the distribution coefficients for Np adsorption on these rocks could range from 10 to 100 ml/g. Independent estimates of K d for Np sorption in similar systems, based on an extensive review of experimental data, are consistent, though slightly conservative, with respect to the calculated values. 31 refs

  8. Metal Sorption to Dolomite Surfaces

    International Nuclear Information System (INIS)

    Brady, P.V.; Papenguth, H.W.; Kelly, J.W.

    1999-01-01

    Potential human intrusion into the Waste Isolation Pilot Plant (WIPP) might release actinides into the Culebra Dolomite where sorption reactions will affect of radiotoxicity from the repository. Using a limited residence time reactor the authors have measured Ca, Mg, Nd adsorption/exchange as a function of ionic strength, P CO2 , and pH at 25 C. By the same approach, but using as input radioactive tracers, adsorption/exchange of Am, Pu, U, and Np on dolomite were measured as a function of ionic strength, P CO2 , and pH at 25 C. Metal adsorption is typically favored at high pH. Calcium and Mg adsorb in near-stoichiometric proportions except at high pH. Adsorption of Ca and Mg is diminished at high ionic strengths (e.g., 0.5M NaCl) pointing to association of Na + with the dolomite surface, and the possibility that Ca and Mg sorb as hydrated, outer-sphere complexes. Sulfate amplifies sorption of Ca and Mg, and possibly Nd as well. Exchange of Nd for surface Ca is favored at high pH, and when Ca levels are low. Exchange for Ca appears to control attachment of actinides to dolomite as well, and high levels of Ca 2+ in solution will decrease Kds. At the same time, to the extent that high P CO2 increase Ca 2+ levels, JK d s will decrease with CO 2 levels as well, but only if sorbing actinide-carbonate complexes are not observed to form (Am-carbonate complexes appear to sorb; Pu-complexes might sorb as well; U-carbonate complexation leads to desorption). This indirect CO 2 effect is observed primarily at, and above, neutral pH. High NaCl levels do not appear to affect to actinide K d s

  9. Heat pipes and solid sorption transformations fundamentals and practical applications

    CERN Document Server

    Vasiliev, LL

    2013-01-01

    Developing clean energy and utilizing waste energy has become increasingly vital. Research targeting the advancement of thermally powered adsorption cooling technologies has progressed in the past few decades, and the awareness of fuel cells and thermally activated (heat pipe heat exchangers) adsorption systems using natural refrigerants and/or alternatives to hydrofluorocarbon-based refrigerants is becoming ever more important. Heat Pipes and Solid Sorption Transformations: Fundamentals and Practical Applications concentrates on state-of-the-art adsorption research and technologies for releva

  10. Effects of humic acid and heavy metals on the sorption of polar and apolar organic pollutants onto biochars.

    Science.gov (United States)

    Wang, Fei; Sun, Hongwen; Ren, Xinhao; Liu, Yarui; Zhu, Hongkai; Zhang, Peng; Ren, Chao

    2017-12-01

    The effects of humic acid (HA) and heavy metals (Cu 2+ and Ag + ) on the sorption of polar and apolar organic pollutants onto biochars that were produced at temperatures of 200 °C (BC200) and 700 °C (BC700) were studied. Due to the plentiful polar functional groups on BC200, cationic propranolol exhibited higher levels of sorption than naphthalene on BC200 while naphthalene and propranolol showed similar sorption capacities on BC700. HA changed the characteristics of biochars and generally inhibited the sorption of target organic pollutants on biochars; however, enhancement occurred in some cases depending on the pollutants involved and their concentrations, biochars used and the addition sequences and concentrations of HA. On BC200, HA modifications mainly influenced sorption by decreasing its polarity and increasing its aromaticity, while on BC700, the surface area and pore volume greatly decreased due to the pore-blocking effects of HA. Residue dissolved HA in solution may also contribute to sorption inhibition. Complexation between polar functional groups on BC200 and heavy metals slightly enhanced the sorption of neutral naphthalene and significantly enhanced that of anionic 4-nitro-1-naphtol, while limited the sorption of cationic propranolol. Heavy metals together with their associated water molecules decreased the sorption of target chemicals on BC700 via pore-filling or pore-mouth-covering. Inhibition of heavy metals for 4-nitro-1-naphthol was found to be the weakest due to the bridge effects of heavy metals between 4-nitro-1-naphtol and BC700. The higher polarizability of Ag + led to the increase of its sorption on biochars in the presence of organic aromatic pollutants. The results of the present study shed light on the sorption mechanisms of bi-solute systems and enable us to select suitable biochar sorbents when chemicals co-exist. Copyright © 2017. Published by Elsevier Ltd.

  11. Sorption of methylxanthines by different sorbents

    Science.gov (United States)

    Dmitrienko, S. G.; Andreeva, E. Yu.; Tolmacheva, V. V.; Terent'eva, E. A.

    2013-05-01

    Sorption of caffeine, theophylline, theobromine, diprophylline, and pentoxyphylline on different sorbents (supercross-linked polystyrene, surface-modified copolymer of styrene and divinylbenzene Strata-X, and carbon nanomaterials Taunit and Diasorb-100-C16T) was studied in a static mode in an effort to find new sorbents suitable for sorption isolation and concentration of methylxanthines. The peculiarities of sorption of methylxanthines were explained in relation to the solution acidity, the nature of the sorbates and their concentration, the nature of the solvent, and the structural characteristics of the sorbents.

  12. Sorption isolation of strontium from seawater

    International Nuclear Information System (INIS)

    Avramenko, V.A.; Zheleznov, V.V.; Kaplun, E.V.; Sokol'nitskaya, T.A.; Yukhkam, A.A.

    2001-01-01

    Sorption isolation of strontium from seawater is considered and prospects of use of selective adsorbents for purification of seawater or liquid radioactive wastes mixed with seawater from 90 Sr are discussed. Comparative analysis of sorptive properties of adsorbents of different nature is done. It is shown that sorption-reagent materials developed by authors can to afford effective separation of 90 Sr from seawater. Possible mechanism of strontium sorption by these adsorbents is considered. The prospect of their use for purification of liquid radioactive wastes from strontium is shown [ru

  13. A new safety assessment model for shallow land burial of LLW based on multicomponent sorption theory

    International Nuclear Information System (INIS)

    Katoh, N.; Asano, T.; Tasaka, H.

    1984-01-01

    A new model on the radionuclide migration in underground environment is developed based on ''multicomponent sorption theory''. The model is capable of predicting the behaviors of the coexisting materials in soil-ground water system as ''multicomponent sorption phenomena'' and also predicting the radinuclide migration affected by the changes of concentrations of coexisting materials. The model is not a ''statistical model'' but a ''chemical model'' based on the ''ion exchange theory'' and ''adsorption theory''. Additionally, the model is a ''kinetic model'' capable of estimating the effect of ''rate of sorption'' on the radionuclide migration. The validity of the model was checked by the results of column experiments for sorption. Finally, sample calculations on the radionuclide migration in reference shallow land burial site were carried out for demonstration

  14. Agro-waste biosorbents: Effect of physico-chemical properties on atrazine and imidacloprid sorption.

    Science.gov (United States)

    Mandal, Abhishek; Singh, Neera; Nain, Lata

    2017-09-02

    Low cost agro-waste biosorbents namely eucalyptus bark (EB), corn cob (CC), bamboo chips (BC), rice straw (RS) and rice husk (RH) were characterized and used to study atrazine and imidacloprid sorption. Adsorption studies suggested that biosorbents greatly varied in their pesticide sorption behaviour. The EB was the best biosorbent to sorb both atrazine and imidacloprid with K F values of 169.9 and 85.71, respectively. The adsorption isotherm were nonlinear in nature with slope (1/n) values imidacloprid sorption parameter [K F .(1/n)] with the physicochemical properties of the biosorbents suggested that atrazine adsorption correlated significantly to the aromaticity, polarity, surface area, fractal dimension, lacunarity and relative C-O band intensity parameters of biosorbents. Probably, both physisorption and electrostatic interactions were responsible for the pesticide sorption. The eucalyptus bark can be exploited as low cost adsorbent for the removal of these pesticides as well as a component of on-farm biopurification systems.

  15. Performance estimation of an oil-free linear compressor unit for a new compact 2K Gifford-McMahon cryocooler

    Science.gov (United States)

    Hiratsuka, Y.; Bao, Q.; Y Xu, M.

    2017-12-01

    Since 2012, a new, compact Gifford-McMahon (GM) cryocooler for cooling superconducting single photon detectors (SSPD) has been developed and reported by Sumitomo Heavy Industries, Ltd. (SHI). Also, it was reported that National Institute of Information and Communications Technology (NICT) developed a multi-channel, conduction-cooled SSPD system. However, the size and power consumption reduction becomes indispensable to apply such a system to the optical communication of AdHoc for a mobile system installed in a vehicle. The objective is to reduce the total height of the expander by 33% relative to the existing RDK-101 GM expander and to reduce the total volume of the compressor unit by 50% relative to the existing CNA-11 compressor. In addition, considering the targeted cooling application, we set the design cooling capacity targets of the first and the second stages 1 W at 60 K and 20 mW at 2.3 K respectively. In 2016, Hiratsuka et al. reported that an oil-free compressor was developed for a 2K GM cryocooler. The cooling performance of a 2K GM expander driven by an experimental unit of the linear compressor was measured. No-load temperature less than 2.1 K and the cooling capacity of 20 mW at 2.3 K were successfully achieved with an electric input power of only 1.1 kW. After that, the compressor capsule and the heat exchanger, etc. were assembled into one enclosure as a compressor unit. The total volume of the compressor unit and electrical box was significantly reduced to about 38 L, which was close to the target of 35 L. Also, the sound noise, vibration characteristics, the effect of the compressor unit inclination and the ambient temperature on the cooling performance, were evaluated. The detailed experimental results are discussed in this paper.

  16. Radiotracer study of sorption of europium on Gorleben sand from aqueous solutions containing humic substances

    International Nuclear Information System (INIS)

    Benes, P.; Stamberg, K.; Siroky, L.; Mizera, J.

    2002-01-01

    The sorption of trace europium, as a trivalent actinide homologue, was studied in the system Gorleben sand - aqueous solution with the aim to elucidate its mechanism. Radiotracer method ( 152/154 Eu) and batch experiments were used. Simultaneously, the distribution of humic substances present in, or added to the system was measured. The evaluation of the sorption was complicated by the adsorption of Eu on the walls of polyethylene vials used for the experiments, which was rather high and had to be taken into consideration. It has been found that Eu sorption on Gorleben sand increases from pH 2 to pH 5-7 and then it decreases. The decrease is due to the complexation of Eu with humic substances leached from Gorleben sand at pH>7. The position of the sorption maximum depends on the composition of the solution and on the liquid-to-solid ratio. It is shifted to lower pH values in the presence of added humic acid (HA), which enhances Eu sorption at low PH values and suppresses it at pH values higher than 5. The regions of the enhancing/suppressing effects coincidence with the high/low adsorption of HA on Gorleben sand, respectively. The increasing ionic strength (from 0.01 to 0.1) and europium concentration (3.4 x 10 -8 to 9.3 x 10 -7 mol/l) suppress the relative sorption (expressed in %) at low pH values and enhance it at pH>6-8. Addition of carbonates (5 x 10 -3 mol/l) supports Eu sorption at pH>7.5 so that no decrease with pH is observed till pH 9. Alkaline leaching of the sand significantly changes most of the effects found. These results were qualitatively interpreted and conclusions were drawn on the mechanism of the sorption. (author)

  17. Effect made by the colloids to the sorption behavior of strontium on granite fracture-fillings

    Science.gov (United States)

    Wang, L.; Zuo, R.

    2017-12-01

    The objective of this study was to investigate the effects made by the colloid to the sorption capacity of colloids in granite fracture-fillings in aqueous solutions. The granite fracture-fillings were collected from three different depth of the research mine in Gansu province. According to the composition of the local soil and groundwater, two colloids were chosen to investigate this sorption process. Batch tests had been investigated at 27° under the air atmosphere as a function of pH(3 11), initial uranium concentration(5 400 mg/L) and water-rock ratio on the sorption of Sr on granite fracture-fillings. The batch experimental results showed that the sorption capacity presented a positive relationship with pH value, which may be caused by the hydrolytic adsorption raised by the reaction between Sr(OH)+ and OH- groups on the surface on the adsorbent. Initial strontium concentration also showed a positive relationship with sorption capacity when the concentration was lower than 200mg/mL, when the concentration was higher than 200mg/ml sorption reached the equilibrium. Sorption percentage showed a positive relationship with water/solid ratios, when the ratio was lower than 1:100 the system got equilibrium. When other experiment parameters were fixed and only the solid-liquid ratio changed, the adsorption capacity increased with the increasing solid-water ratio. The reason was that the total amount of Sr in the adsorption system remained unchanged, the adsorption sites increased with the solid-liquid ratio, and the adsorption capacity increased gradually with the increasing adsorption sites. The experiments data were interpreted in terms of Freundlich and Langmuir isotherms and the data fitted the former better. Equilibrium isotherm studies were used to evaluate the maximum sorption capacity of colloid.

  18. Low-Cost High-Performance Cryocoolers for In-Situ Propellant Production

    Science.gov (United States)

    Martin, J. L.; Corey, J. A.; Peters, T. A.

    1999-01-01

    A key feature of many In-Situ Resource Utilization (ISRU) schemes is the production of rocket fuel and oxidizer from the Martian atmosphere. Many of the fuels under consideration will require cryogenic cooling for efficient long-term storage. Although significant research has been focused on the techniques for producing the fuels from Martian resources, little effort has been expended on the development of cryocoolers to efficiently liquefy these fuels. This paper describes the design of a pulse tube liquefier optimized for liquefying oxygen produced by an In-Situ Propellant Production (ISPP) plant on Mars.

  19. High efficiency, low frequency linear compressor proposed for Gifford-McMahon and pulse tube cryocoolers

    Energy Technology Data Exchange (ETDEWEB)

    Höhne, Jens [Pressure Wave Systems GmbH, Häberlstr. 8, 80337 Munich (Germany)

    2014-01-29

    In order to reduce the amount of greenhouse gas emissions, which are most likely the cause of substantial global warming, a reduction of overall energy consumption is crucial. Low frequency Gifford-McMahon and pulse tube cryocoolers are usually powered by a scroll compressor together with a rotary valve. It has been theoretically shown that the efficiency losses within the rotary valve can be close to 50%{sup 1}. In order to eliminate these losses we propose to use a low frequency linear compressor, which directly generates the pressure wave without using a rotary valve. First results of this development will be presented.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-10-12

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

  2. PCB congener sorption to carbonaceous sediment components: Macroscopic comparison and characterization of sorption kinetics and mechanism

    International Nuclear Information System (INIS)

    Choi, Hyeok; Al-Abed, Souhail R.

    2009-01-01

    Sorption of polychlorinated biphenyls (PCBs) to sediment is a key process in determining their mobility, bioavailability, and chemical decomposition in aquatic environments. In order to examine the validity of currently used interpretation approaches for PCBs sorption, comparative results on 2-chlorobiphenyl sorption to carbonaceous components in sediments (activated carbon, carbon black, coal, soot, graphite, flyash, wood) were macroscopically correlated with the structural, morphological, crystallographic, and compositional properties of the carbonaceous components. Since the Freundlich sorption constant, K F (L kg -1 ) spanned several orders of magnitude, ranging from log K F of 6.13-5.27 for activated carbon, 5.04 for carbon black, 3.83 for coal to 3.08 for wood, organic carbon partitioning approach should be more specifically categorized, considering the various forms, nature and origins of organic carbon in sediment. Sorption rate constants and fraction parameters, which were numerically defined from empirical kinetic model with fast and slow sorption fractions, were closely related to the physicochemical properties of the carbonaceous components. Sorption interpretation approaches with a specific property and viewpoint, such as organic carbon partitioning, soot carbon distribution, or surface area correlation, did not properly explain the overall results on sorption capacity, fast and slow sorption kinetics, and partitioning coefficient. It is also important to emphasize the heterogeneous nature of sediment and the difficulties of encompassing the partitioning among its carbonaceous components.

  3. PCB congener sorption to carbonaceous sediment components: Macroscopic comparison and characterization of sorption kinetics and mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hyeok [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268 (United States); Al-Abed, Souhail R., E-mail: al-abed.souhail@epa.gov [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268 (United States)

    2009-06-15

    Sorption of polychlorinated biphenyls (PCBs) to sediment is a key process in determining their mobility, bioavailability, and chemical decomposition in aquatic environments. In order to examine the validity of currently used interpretation approaches for PCBs sorption, comparative results on 2-chlorobiphenyl sorption to carbonaceous components in sediments (activated carbon, carbon black, coal, soot, graphite, flyash, wood) were macroscopically correlated with the structural, morphological, crystallographic, and compositional properties of the carbonaceous components. Since the Freundlich sorption constant, K{sub F} (L kg{sup -1}) spanned several orders of magnitude, ranging from log K{sub F} of 6.13-5.27 for activated carbon, 5.04 for carbon black, 3.83 for coal to 3.08 for wood, organic carbon partitioning approach should be more specifically categorized, considering the various forms, nature and origins of organic carbon in sediment. Sorption rate constants and fraction parameters, which were numerically defined from empirical kinetic model with fast and slow sorption fractions, were closely related to the physicochemical properties of the carbonaceous components. Sorption interpretation approaches with a specific property and viewpoint, such as organic carbon partitioning, soot carbon distribution, or surface area correlation, did not properly explain the overall results on sorption capacity, fast and slow sorption kinetics, and partitioning coefficient. It is also important to emphasize the heterogeneous nature of sediment and the difficulties of encompassing the partitioning among its carbonaceous components.

  4. Sorption and Migration Mechanisms of 237 Np through Sandy Soil

    International Nuclear Information System (INIS)

    Chantaraprachoom, Nanthavan; Tanaka, Tadao

    2003-06-01

    In order to evaluate migration behavior of radioactive nuclides in the disposal of low-level radioactive waste into a shallow land burial, the sorption characteristic and migration behavior of 237 Np through sandy soil was studied. Two experimental methods were performed by using batch and column systems. The distribution coefficients (K d ) obtained from the adsorption and desorption process are rather small about 16 and 21 cm 3 /g respectively. Size distribution of 237 Np species in the influent solution was measured by ultra-filtration technique. Migration mechanism of 237 Np was studied by column experiments. The experimental condition was the influence of volume of eluting solution; 100, 300, 500, 1000 and 2000 ml respectively. The result from five column experiments confirm that the sorption characteristics of 237 Np are mainly controlled by a reversible ion-exchange reaction and the migration of 237 Np in the sandy soil can be estimated by using the K d concept

  5. Uranium (Vi) sorption onto zirconium diphosphate chemically modified

    International Nuclear Information System (INIS)

    Garcia G, N.; Ordonez R, E.

    2010-10-01

    This work deals with the uranium (Vi) speciation after sorption onto zirconium diphosphate (ZrP 2 O 7 ) surface, hydrated and in a surface modified with organic acids. Oxalic and citric acids were chosen to modify the ZrP 2 O 7 surface because they have poly carboxylic groups and they mimic the organic matter in nature. Thus the interest of this work is to evaluate the uranium (Vi) sorption edge at different s ph values in natural and modified surfaces. The luminescence technique (fluorescence and phosphorescence, respectively) was used for the quantification and speciation of uranyl sorbed at the zirconium diphosphate interface. The fluorescence experiment, showed that adsorption of uranyl on surface of zirconium diphosphate tends to 100%. The speciation shows that there are different complexes in surface which were formed between zirconium diphosphate and uranyl, since it is produced a displacement of wavelength in fluorescence spectra of each system. (Author)

  6. Carbon dioxide sorption on EDTA modified halloysite

    Directory of Open Access Journals (Sweden)

    Waszczuk Patrycja

    2016-01-01

    Full Text Available In this paper the sorption study of CO2 on EDTA surface modified halloysite was conducted. In the paper chemical modification of halloysite from the Dunino deposit (Poland and its influence on sorption of CO2 are presented. A halloysite samples were washed with water-EDTA 1% solution, centrifuged to separate liquid and impurities and dried. The samples were tested for the sorption capacity using a manometric method with pressure up to 3 MPa. A Langmuir adsorption model was fitted to the data. The results showed that EDTA had a limited effect on the increase of sorption potential at low pressure and the samples exhibited similar results to that ones treated solely with the water solution.

  7. Sorption of metaldehyde using granular activated carbon

    Directory of Open Access Journals (Sweden)

    S. Salvestrini

    2017-09-01

    Full Text Available In this work, the ability of granular activated carbon (GAC to sorb metaldehyde was evaluated. The kinetic data could be described by an intra-particle diffusion model, which indicated that the porosity of the sorbent strongly influenced the rate of sorption. The analysis of the equilibrium sorption data revealed that ionic strength and temperature did not play any significant role in the metaldehyde uptake. The sorption isotherms were successfully predicted by the Freundlich model. The GAC used in this paper exhibited a higher affinity and sorption capacity for metaldehyde with respect to other GACs studied in previous works, probably as a result of its higher specific surface area and high point of zero charge.

  8. Study of sorption of technetium on pyrrhotine

    International Nuclear Information System (INIS)

    Shen Dong; Fan Xianhua; Su Xiguang; Zeng Jishu

    2001-01-01

    The sorption behaviors of technetium on pyrrhotine are studied with batch experiment and dilute sulfuric acid is used to dissolve the technetium adsorbed on pyrrhotine. Sorption and desorption experiment are performed under aerobic and anaerobic conditions (inert gas box). The results show that a significant sorption of technetium on pyrrhotine is found under aerobic and anaerobic conditions, and the sorption on the mineral is supposed to be due to the reduction of TcO 4 - to insoluble TcO 2 ·nH 2 O. Desorption process of the sorbed technetium into dilute sulfuric acid is found to be different under aerobic and anaerobic conditions. On addition of H 2 O 2 to the leach solution a sudden increase of the technetium concentration is observed

  9. Radionuclide sorption on granitic drill core material

    International Nuclear Information System (INIS)

    Eriksen, T.E.; Locklund, B.

    1987-11-01

    Distribution ratios were determined for Sr-85, Cs-134 and Eu-152 on crushed granite and fissure coating/filling material from Stripa mines. Measurements were also carried out on intact fissure surfaces. The experimental data for Sr-85, Cs-134 on crushed material can be accomodated by a sorption model based on the assumption that the crushed material consists of porous spheres with outer and inner surfaces available for sorption. In the case of Eu-152 only sorption on the outer surfaces of the crushed material was observed. The absence of sorption on inner surfaces is most probably due to high depletion of the more strongly sorbed Eu-152 in the water phase and very low diffusivity of Eu-152 in the sorbed state. (orig./HP)

  10. Hollow fiber adsorbents for CO2 capture: Kinetic sorption performance

    KAUST Repository

    Lively, Ryan P.

    2011-07-01

    We describe a CO 2 capture platform based on hollow polymeric fibers with sorbent particles embedded in the porous fiber wall for post-combustion CO 2 capture. These fibers are intended for use in a rapid temperature swing adsorption (RTSA) process. The RTSA system utilizes the hollow fiber morphology by flowing cooling water on the bore-side of the fibers during sorption to prevent temperature rise associated with the sorption enthalpy. Steam or hot water is flowed through the bores during desorption to desorb CO 2 rapidly. To minimize material transfer between the bore and the fiber wall, a dense Neoprene ® lumen layer is cast on the bore-side of the fiber wall. In this paper, the key sorption step and associated kinetic resistances for the uncooled fibers are examined and evaluated for this portion of the RTSA process. Chopped fibers in a packed bed, as well as fibers assembled into a parallel flow module, have been tested in a simulated flue gas stream. Kinetic limitations in the hollow fiber modules are largely overcome by increasing the superficial gas velocity and the fiber packing in the module-indicating that film diffusion is the controlling mass transfer limitation in the fiber system. The un-cooled fiber modules lose apparent capacity as superficial velocities are increased, likely indicating non-isothermal operation, whereas the actively-cooled fibers in the packed bed maintain apparent capacity at all flowrates studied. © 2011 Elsevier B.V.

  11. Sorption of heteropoly acids by polyurethane foam

    International Nuclear Information System (INIS)

    Dmitreinko, S.G.; Goncharova, L.V.; Runov, V.K.; Zakharov, V.N.; Aslanova, L.A.

    1997-01-01

    Sorption of oxidized and reduced forms of molybdosilicic, molybdophosphoric and molybdovanadophosphoric acids by polyurethane foam based on ethers and esters is studied. On the basis of sorption dependence on solution pH, polyurethane foam type and spectral characteristics of sorbates the suggestion has been made that in the polyurethane foam phase there are two main types of sorbent-sorbate interaction: electrostatic (ion-ion) and with hydrogen bond formation: and it is impossible to determine the contribution of every interaction

  12. Sorption of organophosphate esters by carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Wei; Yan, Li [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Duan, Jinming [School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Jing, Chuanyong, E-mail: cyjing@rcees.ac.cn [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2014-05-01

    Graphical abstract: The interfacial interactions between the OPE molecules and CNTs. - Highlights: • Oxygen-containing groups on CNTs change the sorption property for OPEs. • Molecular configuration of OPEs has insignificant impact on their sorption. • Hydrophobic, π–π EDA and Brønsted acid–base interaction occurred between the CNTs and OPEs. - Abstract: Insights from the molecular-level mechanism of sorption of organophosphate esters (OPEs) on carbon nanotubes (CNTs) can further our understanding of the fate and transport of OPEs in the environment. The motivation for our study was to explore the sorption process of OPEs on multi-walled CNTs (MWCNTs), single-walled CNTs (SWCNTs) and their oxidized counterparts (O-MWCNTs and O-SWCNTs), and its molecular mechanism over a wide concentration range. The sorption isotherm results revealed that the hydrophobicity of OPEs dominated their affinities on a given CNT and the π–π electron donor–acceptor (EDA) interaction also played an important role in the sorption of aromatic OPEs. This π–π EDA interaction, verified with Raman and FT-IR spectroscopy, could restrict the radial vibration of SWCNTs and affect the deformation vibration γ(CH) bands of OPE molecules. The OPE surface coverage on CNTs, estimated using the nonlinear Dubinin–Ashtakhov model, indicated that the oxygen-containing functional groups on CNTs could interact with water molecules by H-bonding, resulting in a decrease in effective sorption sites. In addition, FTIR analysis also confirmed the occurrence of Brønsted acid–base interactions between OPEs and surface OH groups of SWCNTs. Our results should provide mechanistic insights into the sorption mechanism of OPE contaminants on CNTs.

  13. Sorption of cesium and uranium to Feldspar

    International Nuclear Information System (INIS)

    Wijland, G.C.; Pennders, R.M.J.

    1990-07-01

    Within safety assessment studies, for nuclear waste disposal in deep geologic formations, calculation for the migration of radionuclides through the geosphere are often carried out with models taking sorption into account. In the past 8 years the insight grew that other physico-chemical processes, besides sorption, could affect migration behaviour. While the currently used transport models were being improved taking either linear or non-linear sorption into account, the coupling of geochemical and transport models came into scope. In spite of these developments models which are still based on the sorption theory are frequently applied in studying migration behaviour of radionuclides. This is caused by the necessity of making preliminary pronouncements, while coupled models are still in stage of development and thermodynamic data are very limited available. Therefore one has to obtain insight in the reliability of the models based on the sorption theory. within the sorption database there is a lack of knowledge about mineralogy, composition of the fluid and the experimental conditions underlying the data. Therefore the Expert Group on geochemical Modelling supported by the Finnish proposal in order to obtain insight in the possible deviation of the sorption coefficients that can be estimated from experiments performed with standard samples, fluid composition and experimental conditions. Nine laboratories from OECD membership countries took part in this intercalibration study. In the framework of the Dutch safety assessment studies the Dutch National Institute of Public health and Environmental protection (RIVM) has decided to participate in this exercise. In this report the results are presented of sorption experiments for cesium and natural Uranium to Feldspar. (H.W.). 4 refs.; 1 fig.; 7 tabs

  14. Sorption of fomesafen in Brazilian soils

    OpenAIRE

    Silva,G.R.; D'Antonino,L.; Faustino,L.A.; Silva,A.A.; Ferreira,F.A.; Texeira,C.C.

    2013-01-01

    The study of the dynamics of a herbicide in the soil focus on the interactions with environmental components to obtain agronomic efficiency, ensuring selectivity to the culture and risk reduction of environmental impact. This study evaluated the sorption process of fomesafen in the Brazilian soils Ultisol, Cambisol, and Organosol. Besides soil, washed sand was used as an inert material for determination of the sorption ratio of fomesafen in the soil. The bioassay method was applied, using Sor...

  15. Kinetics of strontium sorption in calcium phosphate

    International Nuclear Information System (INIS)

    Bacic, S.; Komarov, V.F.; Vukovic, Z.

    1989-01-01

    Kinetics of strontium sorption by highly dispersed solids: tricalcium phosphate (Ca 3 (PO 4 ) 2 , TCP) and hydroxyapatite (Ca 5 (PO 4 ) 3 )H, HAP) were investigated. Analysis of sorption data was made taking into consideration composition and morphology of ultra micro particles. Conclusion is that the isomorphous strontium impurity is structurally sensitive element for calcium phosphate. It was determined that the beginning of strontium desorption corresponds to the beginning of transformation of the TCP - HAP (author)

  16. Iodine sorption by microwave irradiated hydrotalcites

    Energy Technology Data Exchange (ETDEWEB)

    Paredes, S.P. [Universidad Autonoma de Puebla, Facultad de Ciencias Quimicas, C.P. 72570, Puebla, Pue (Mexico); Instituto Politecnico Nacional, ESIQIE, C.P. 07738, Mexico, D.F. (Mexico); Fetter, G. [Universidad Autonoma de Puebla, Facultad de Ciencias Quimicas, C.P. 72570, Puebla, Pue (Mexico)]. E-mail: geolarfetter@yahoo.com.mx; Bosch, P. [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones en Materiales, C.P. 04510, Mexico, D.F. (Mexico); Bulbulian, S. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, C.P. 11801, Mexico, D.F. (Mexico)

    2006-12-15

    Mg-Al hydrotalcite-like compounds (HT) were prepared by the microwave method on the one hand with ethoxide-acetylacetonate and on the other with acetylacetonate as precursors. They presented a maximum sorption capacity of 2.179 and 1.517 meq of {sup 131}I{sup -}/g of hydrotalcite respectively. When the hydrotalcites were calcined and rehydrated in a {sup 131}I{sup -} solution, iodine sorption decreased in both samples to 1.515 and 1.446, respectively. The corresponding value for nitrated hydrotalcite which was prepared by the conventional method for comparison purposes, was 0.570. The radionuclide content in hydrotalcites was determined by {gamma}-spectrometry. {sup 131}I{sup -} sorption is dependent on two main parameters: one is the type of the interlayer organic material and the second the surface area. It was found that hydrotalcites prepared with ethoxide-acetylacetonate were better sorbents for {sup 131}I{sup -} than those with acetylacetonate. Still, if the specific surface area increased, {sup 131}I{sup -}sorption increased as well; nitrated HT resulted in low specific surface area and a low sorption capacity. It is, therefore, concluded that organic residues present in the samples prepared by the microwave method favor the sorption of radioactive anions, in particular {sup 131}I{sup -} if compared with nitrated and/or carbonate interlayered hydrotalcites.

  17. Sorption of copper, zinc and cobalt by oat and oat products.

    Science.gov (United States)

    Górecka, Danuta; Stachowiak, Jadwiga

    2002-04-01

    We determined copper, zinc and cobalt sorption by oat and its products under variable pH conditions as well as the content of neutral dietary fiber (NDF) and its fractional composition. Adsorbents in a model sorption system were: oat, dehulled oat, oats bran and oats flakes. Three various buffers (pH 1.8, 6.6 and 8.7) were used as dispersing solutions. Results collected during this study indicate that copper, zinc and cobalt sorption is significantly affected by the type of cereal raw material. Zinc and copper ions are subjected to higher sorption than cobalt ions. Examined metal ions were subjected to high sorption under conditions corresponding to the duodenum environment (pH 8.7), regardless of the kind of adsorbent. A little lower sorption capacity is observed under conditions close to the neutral environment, while the lowest one is found in environment reflecting conditions of stomach juice (pH 1.8). Zinc ions are bound intensively by dehulled oat, while oats flakes bound mostly copper and cobalt, independently on environmental conditions. Contents of dietary fiber in oat, dehulled oat, oat bran and oat flakes were: 40.1, 19.3, 20.3 and 14.3%, respectively. The dominating fraction in all oat products was the fraction of hemicelluloses. The content of remaining fractions varies in dependence on the product.

  18. Sorption of cadmium and lead by clays from municipal incinerator ash- water suspensions

    Science.gov (United States)

    Roy, W.R.; Krapac, I.G.; Steele, J.D.

    1993-01-01

    The effect of Cl complexation in extracts of a flue gas-scrubber incinerator fly ash sample on the sorption of Cd and Pb by kaolinite and illite was investigated using batch-sorption methods. In the pH range of 5 to 9, Cl complexation may reduce sorption and thus increase the mobility of these metals. When an ash-water suspension was acidified to pH 6.85, the dissolution of Cl and Ca essentially eliminated Cd sorption because of complexation and cationic competition. Cadmium would be considered as either mobile or very mobile under these conditions. Lead was not soluble in the pH- 6.85 suspension. At pH 12, the approximate pH of water in contact with flue gas-scrubber fly ash, Cd was essentially insoluble and Pb occurred as anionic Pb hydroxide. Anionic Pb was sorbed by the two clays, and the extent of sorption was not influenced by Cl or carbonate complexation. Sorption constants, derived from isotherms, suggested that Pb would be relatively immobile in saturated soil-water systems. The recent concern that highly alkaline, flue gas-scrubber fly ash may release environmentally significant concentrations of mobile Pb when placed in an ash-disposal site with a soil liner should be reevaluated in light of this study.

  19. Removal of cobalt and strontium from groundwater by sorption onto fishbone

    International Nuclear Information System (INIS)

    Younjin Park; Won Sik Shin; Sang-June Choi

    2013-01-01

    Fishbone as a main backfill material of permeable reactive barrier to remediate groundwater contaminated with Co and Sr was investigated through single- and bi-solute competitive sorptions. The single-solute sorption data were fitted by Freundlich, Langmuir and Dubinin-Radushkevich models. The coefficients of determination (R 2 > 0.91) indicated that all models fitted well. Maximum sorption capacities (q mL ) of Co and Sr predicted by the Langmuir model were 0.55 mmol/g and 0.50 mmol/g, respectively. The bi-solute competitive sorption of the metals was analyzed by the Langmuir, competitive Langmuir, Sheindorf-Rebhun-Sheintuch (SRS) and P-factor models. The sorbed amount of one solute in bi-solute system decreased due to competition with the other solute. Langmuir model parameters for single- (q mL and b L ) and bi-solute (q mL * and b L * ) competitive sorptions were compared to analyze the effect of competition between the metals. The competitive Langmuir, SRS and P-factor models predicted the bi-solute competitive sorption data well (R 2 > 0.93). (author)

  20. Sorption and biodegradation characteristics of the selected pharmaceuticals and personal care products onto tropical soil.

    Science.gov (United States)

    Foolad, Mahsa; Hu, Jiangyong; Tran, Ngoc Han; Ong, Say Leong

    2016-01-01

    In the present study, the sorption and biodegradation characteristics of five pharmaceutical and personal care products (PPCPs), including acetaminophen (ACT), carbamazepine (CBZ), crotamiton (CTMT), diethyltoluamide (DEET) and salicylic acid (SA), were studied in laboratory-batch experiments. Sorption kinetics experimental data showed that sorption systems under this study were more appropriately described by the pseudo second-order kinetics with a correlation coefficient (R2)>0.98. Sorption equilibrium data of almost all target compounds onto soil could be better described by the Freundlich sorption isotherm model. The adsorption results showed higher soil affinity for SA, following by ACT. Results also indicated a slight effect of pH on PPCP adsorption with lower pH causing lower adsorption of compounds onto the soil except for SA at pH 12. Moreover, adsorption of PPCPs onto the soil was influenced by natural organic matter (NOM) since the higher amount of NOM caused lower adsorption to the soil. Biodegradation studies of selected PPCPs by indigenous microbial community present in soil appeared that the removal rates of ACT, SA and DEET increased with time while no effect had been observed for the rest. This study suggests that the CBZ and CTMT can be considered as suitable chemical sewage indicators based on their low sorption affinity and high resistance to biodegradation.

  1. Kinetic characteristic of phenanthrene sorption in aged soil amended with biochar

    Science.gov (United States)

    Kim, Chanyang; Kim, Yong-Seong; Hyun, Seunghun

    2015-04-01

    Biochar has been recently highlighted as an amendment that affects yield of the crops by increasing pH, cation exchange capacity and water retention, and reduces the lability of contaminants by increasing sorption capacity in the soil system. Biochar's physico-chemical properties, high CEC, surfaces containing abundant micropores and macropores, and various types of functional groups, play important roles in enhancing sorption capacity of contaminants. Aging through a natural weathering process might change physico-chemical properties of biochar amended in soils, which can affect the sorption behavior of contaminants. Thus, in this study, the sorption characteristics of phenanthrene (PHE) on biochar-amended soils were studied with various types of chars depending on aging time. To do this, 1) soil was amended with sludge waste char (SWC), wood char (WC), and municipal waste char (MWC) during 0, 6, and 12 month. Chars were applied to soil at 1% and 2.5% (w/w) ratio. 2) Several batch kinetic and equilibrium studies were conducted. One-compartment first order and two-compartment first order model apportioning the fraction of fast and slow sorbing were selected for kinetic models. Where, qt is PHE concentration in biochar-amended soils at each time t, qeis PHE concentration in biochar-amended soils at equilibrium. ff is fastly sorbing fraction and (1-ff) is slowly sorbing fraction. k is sorption rate constant from one-compartment first order model, k1 and k2 are sorption rate constant from two-compartment first order model, t is time (hr). The equilibrium sorption data were fitted with Fruendlich and Langmuir equation. 3) Change in physico-chemical properties of biochar-amended soils was investigated with aging time. Batch equilibrium sorption results suggested that sorbed amount of PHE on WC was greater than SWC and MWC. The more char contents added to soil, the greater sorption capacity of PHE. Sorption equilibrium was reached after 4 hours and equilibrium pH ranged

  2. A cryogenic tensile testing apparatus for micro-samples cooled by miniature pulse tube cryocooler

    International Nuclear Information System (INIS)

    Chen, L B; Liu, S X; Gu, K X; Zhou, Y; Wang, J J

    2015-01-01

    This paper introduces a cryogenic tensile testing apparatus for micro-samples cooled by a miniature pulse tube cryocooler. At present, tensile tests are widely applied to measure the mechanical properties of materials; most of the cryogenic tensile testing apparatus are designed for samples with standard sizes, while for non-standard size samples, especially for microsamples, the tensile testing cannot be conducted. The general approach to cool down the specimens for tensile testing is by using of liquid nitrogen or liquid helium, which is not convenient: it is difficult to keep the temperature of the specimens at an arbitrary set point precisely, besides, in some occasions, liquid nitrogen, especially liquid helium, is not easily available. To overcome these limitations, a cryogenic tensile testing apparatus cooled by a high frequency pulse tube cryocooler has been designed, built and tested. The operating temperatures of the developed tensile testing apparatus cover from 20 K to room temperature with a controlling precision of ±10 mK. The apparatus configurations, the methods of operation and some cooling performance will be described in this paper. (paper)

  3. Numerical Simulation of Magnetic Field Effect on Cryocooler Regenerators: Temperature Distribution

    Directory of Open Access Journals (Sweden)

    Rajendra Kumar

    2017-01-01

    Full Text Available Regenerative types of cryogenic refrigerators (or cryocoolers employ magnetic intermetallic compounds of 3d and 4f elements to work well below 10 K. This paper presents the analysis of temperature distribution in regenerators of such cryocoolers under the influence of magnetic fields of 1 T, 3 T, and 4.3 T. Commercial code of finite element analysis (FEA package, ANSYS (APDL 14.5, is used to investigate the temperature distribution under above-mentioned fields. Er3Ni is selected as regenerator material and the criteria for its selection are discussed in detail. The cold end temperature is varied from 4.2 K to 10 K and hot end temperature is fixed at 20 K. The values obtained from FEA clearly show that the ineffectiveness of Er3Ni is at 8 K and 10 K at 3 T and 4.3 T.

  4. Study of reverse Brayton cryocooler with Helium-Neon mixture for HTS cable

    Science.gov (United States)

    Dhillon, A. K.; Ghosh, P.

    2017-12-01

    As observed in the earlier studies, helium is more efficient than neon as a refrigerant in a reverse Brayton cryocooler (RBC) from the thermodynamic point of view. However, the lower molecular weight of helium leads to higher refrigerant inventory as compared to neon. Thus, helium is suitable to realize the high thermodynamic efficiency of RBC whereas neon is appropriate for the compactness of the RBC. A binary mixture of helium and neon can be used to achieve high thermodynamic efficiency in the compact reverse Brayton cycle (RBC) based cryocooler. In this paper, an attempt has been made to analyze the thermodynamic performance of the RBC with a binary mixture of helium and neon as the working fluid to provide 1 kW cooling load for high temperature superconductor (HTS) power cables working with a temperature range of 50 K to 70 K. The basic RBC is simulated using Aspen HYSYS V8.6®, a commercial process simulator. Sizing of each component based on the optimized process parameters for each refrigerant is performed based on a computer code developed using Engineering Equation Solver (EES-V9.1). The recommendation is provided for the optimum mixture composition of the refrigerant based on the trade-off factors like thermodynamic efficiency such as the exergy efficiency and equipment considerations. The outcome of this study may be useful for recommending a suitable refrigerant for the RBC operating at a temperature level of 50 K to 70 K.

  5. Studies of cryocooler based cryosorption pump with activated carbon panels operating at 11K

    International Nuclear Information System (INIS)

    Kasthurirengan, S; Behera, Upendra; Gangradey, Ranjana; Udgata, Swarup; Krishnamoorthy, V

    2012-01-01

    Cryosorption pump is the only solution for pumping helium and hydrogen in fusion reactors. It is chosen because it offers highest pumping speed as well as the only suitable pump for the harsh environments in a tokamak. Towards the development of such cryosorption pumps, the optimal choice of the right activated carbon panels is essential. In order to characterize the performance of the panels with indigenously developed activated carbon, a cryocooler based cryosorption pump with scaled down sizes of panels is experimented. The results are compared with the commercial cryopanel used in a CTI cryosorption (model: Cryotorr 7) pump. The cryopanel is mounted on the cold head of the second stage GM cryocooler which cools the cryopanel down to 11K with first stage reaching about ∼50K. With no heat load, cryopump gives the ultimate vacuum of 2.1E-7 mbar. The pumping speed of different gases such as nitrogen, argon, hydrogen, helium are tested both on indigenous and commercial cryopanel. These studies serve as a bench mark towards the development of better cryopanels to be cooled by liquid helium for use with tokamak.

  6. The study on a gas-coupled two-stage stirling-type pulse tube cryocooler

    Science.gov (United States)

    Wu, X. L.; Chen, L. B.; Zhu, X. S.; Pan, C. Z.; Guo, J.; Wang, J. J.; Zhou, Y.

    2017-12-01

    A two-stage gas-coupled Stirling-type pulse tube cryocooler (SPTC) driven by a linear dual-opposed compressor has been designed, manufactured and tested. Both of the stages adopted coaxial structure for compactness. The effect of a cold double-inlet at the second stage on the cooling performance was investigated. The test results show that the cold double-inlet will help to achieve a lower cooling temperature, but it is not conducive to achieving a higher cooling capacity. At present, without the cold double-inlet, the second stage has achieved a no-load temperature of 11.28 K and a cooling capacity of 620 mW/20 K with an input electric power of 450 W. With the cold double-inlet, the no-load temperature is lowered to 9.4 K, but the cooling capacity is reduced to 400 mW/20 K. The structure of the developed cryocooler and the influences of charge pressure, operating frequency and hot end temperature will also be introduced in this paper.

  7. Neptunium(V) sorption on kaolinite

    Energy Technology Data Exchange (ETDEWEB)

    Amayri, S.; Jermolajev, A.; Reich, T. [Mainz Univ. (Germany). Inst. of Nuclear Chemistry

    2011-07-01

    The sorption behavior of neptunium(V) onto the clay mineral kaolinite was studied in batch experiments under different experimental conditions: [Np(V)] = 7 x 10{sup -12}-8 x 10{sup -6} M, solid-to-liquid ratio 2-20 g L{sup -1}, I = 0.1 and 0.01 M NaClO{sub 4}, pH = 6-10, ambient air and Ar atmosphere. The short-lived isotope {sup 239}Np (T{sub 1/2} = 2.36 d) was used instead of {sup 237}Np (T{sub 1/2} = 2.14 x 10{sup 6} a) to study the sorption behavior of Np(V) at environmentally-relevant concentrations, i.e., 7 x 10{sup -12} M Np. In addition, {sup 239}Np(V) served as tracer to measure sorption isotherms over six orders of magnitude in Np concentration (4.8 x 10{sup -12}-1.0 x 10{sup -4} M). The results show that Np(V) sorption on kaolinite is strongly influenced by pH, CO{sub 2}, and ionic strength. The sorption of 8 x 10{sup -6} M Np(V) at pH 9.0, and ionic strength of 0.1 M NaClO{sub 4} was proportional to the solid-to-liquid ratio of kaolinite in the range of 2-10 g L{sup -1}. In the absence of CO{sub 2}, the Np(V) uptake increased continuously with increasing pH value up to 97% at pH 10. Under ambient CO{sub 2}, the sorption of Np decreased above pH 8 up to zero at pH 10. An increase of Np(V) concentration from 7 x 10{sup -12} to 8 x 10{sup -6} M resulted in a shift of the sorption pH edge by up to one pH unit to higher pH values. The ionic strength influenced the Np(V) sorption onto kaolinite only in the presence of ambient CO{sub 2}. Under Ar atmosphere the sorption of Np(V) was independent from ionic strength, indicating the formation of inner-sphere complexes of Np(V) with kaolinite. Time-dependent batch experiments at pH 9.0 under ambient CO{sub 2} showed that the sorption of Np(V) on kaolinite is fast and fully reversible over six orders in Np(V) concentration. (orig.)

  8. Effect of competing cations on strontium sorption to surficial sediments

    International Nuclear Information System (INIS)

    Bunde, R.L.; Rosentreter, J.J.

    1995-01-01

    The following study was conducted to determine strontium distribution coefficients (K d 'S) of a surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. Batch experimental techniques were used to determine K d 's which describe the partitioning of a solute between the solution and solid phase. A surficial sediment was mixed with synthesized aqueous solutions designed to chemically simulate wastewater disposed to infiltrations ponds near the Idaho Chemical Processing Plant at the INEL with respect to major ionic character and pH. The effects of variable concentrations of competing cations (sodium, potassium, calcium and magnesium) on strontium sorption were investigated at a fixed pH of 8.00. The pH of the natural system shows no appreciable variation, whereas a marked variability in cation concentration has been noted. Strontium sorption was impacted to a greater degree by the concentration of calcium and magnesium in solution than by the presence of sodium or potassium. However, extreme sodium solution concentrations of 1.0 to 5.0 g/L dramatically reduced strontium sorption. In all cases, strontium K d 's decreased as the concentration of calcium and magnesium in solution increased. Linear isotherm model K d 's ranged from 12.0 to 84.7 mL/g. Analysis of data from these experiments indicated that moderate concentrations of calcium and magnesium (less than 40 mg/L) and high concentrations of sodium (1.0 to 5.0 g/L) in wastewater increase strontium mobility by decreasing the sorption of strontium on surficial sediments beneath infiltration ponds at the INEL

  9. Pesticide sorption and leaching potential on three Hawaiian soils.

    Science.gov (United States)

    Hall, Kathleen E; Ray, Chittaranjan; Ki, Seo Jin; Spokas, Kurt A; Koskinen, William C

    2015-08-15

    On the Hawaiian Islands, groundwater is the principal source of potable water and contamination of this key resource by pesticides is of great concern. To evaluate the leaching potential of four weak acid herbicides [aminocyclopyrachlor, picloram, metsulfuron-methyl, biologically active diketonitrile degradate of isoxaflutole (DKN)] and two neutral non-ionizable herbicides [oxyfluorfen, alachlor], their sorption coefficients were determined on three prevalent soils from the island of Oahu. Metsulfuron-methyl, aminocylcopyrachlor, picloram, and DKN were relatively low sorbing herbicides (K(oc) = 3-53 mL g(-1)), alachlor was intermediate (K(oc) = 120-150 mL g(-1)), and oxyfluorfen sorbed very strongly to the three soils (K(oc) > 12,000 mL g(-1)). Following determination of K(oc) values, the groundwater ubiquity score (GUS) indices for these compounds were calculated to predicted their behavior with the Comprehensive Leaching Risk Assessment System (CLEARS; Tier-1 methodology for Hawaii). Metsulfuron-methyl, aminocyclopyrachlor, picloram, and DKN would be categorized as likely leachers in all three Hawaiian soils, indicating a high risk of groundwater contamination across the island of Oahu. In contrast, oxyfluorfen, regardless of the degradation rate, would possess a low and acceptable leaching risk due to its high sorption on all three soils. The leaching potential of alachlor was more difficult to classify, with a GUS value between 1.8 and 2.8. In addition, four different biochar amendments to these soils did not significantly alter their sorption capacities for aminocyclopyrachlor, indicating a relatively low impact of black carbon additions from geologic volcanic inputs of black carbon. Due to the fact that pesticide environmental risks are chiefly dependent on local soil characteristics, this work has demonstrated that once soil specific sorption parameters are known one can assess the potential pesticide leaching risks. Published by Elsevier Ltd.

  10. U(VI) sorption on granite: prediction and experiments

    International Nuclear Information System (INIS)

    Nebelung, C.; Brendler, V.

    2010-01-01

    One widely accepted approach - component additivity (CA) - to describe the sorption of contaminants onto complex materials such as rocks or soils is based on the assumption that the surface of a complex mineral assemblage is composed of a mixture of mineral constituents whose surface properties are known from independent studies. An internally consistent SCM (surface complexation model) database can be developed that describes the adsorption reactions of solutes to each phase. Here, the capability of such a methodology was tested, using the code MINTEQA2 including thermodynamic data of the NEA-TDB, and literature data for SCM, namely the DDL model. The sorption characteristics of U(VI) on granite (from Eibenstock, Saxony, Germany, with the main components quartz, albite, orthoclase, and muscovite) was predicted and then compared to batch experiments. Granite plays an important role in the remediation of former uranium ore mining and milling sites, but is also one of the host rocks considered for final disposal of nuclear materials. Safety assessment requires a detailed understanding of this system and its retention potential with regard to hazardous components. Namely the sorption of uranium in this complex rock is not fully understood yet. The experiments thus also provided a better understanding of the far-field behaviour in granitic geological nuclear repositories. The robustness of the prediction was tested by variation of the granite composition and the variation of the specific surface area (SSA) - first all components were predicted with a uniform granite SSA, second with a distinct SSA for each granite component (determined on pure minerals for the same grain size fractions). Changes in compositions yielded only marginal differences in the prediction. Different approaches to SSA showed somewhat larger deviations. In conclusion, the CA methodology is a valid and robust approach to U(VI) sorption onto complex substrates such as granite, provided sufficient

  11. Ultrafast Carbon Dioxide Sorption Kinetics Using Lithium Silicate Nanowires.

    Science.gov (United States)

    Nambo, Apolo; He, Juan; Nguyen, Tu Quang; Atla, Veerendra; Druffel, Thad; Sunkara, Mahendra

    2017-06-14

    In this paper, the Li 4 SiO 4 nanowires (NWs) were shown to be promising for CO 2 capture with ultrafast kinetics. Specifically, the nanowire powders exhibited an uptake of 0.35 g g -1 of CO 2 at an ultrafast adsorption rate of 0.22 g g -1 min -1 at 650-700 °C. Lithium silicate (Li 4 SiO 4 ) nanowires and nanopowders were synthesized using a "solvo-plasma" technique involving plasma oxidation of silicon precursors mixed with lithium hydroxide. The kinetic parameter values (k) extracted from sorption kinetics obtained using NW powders are 1 order of magnitude higher than those previously reported for the Li 4 SiO 4 -CO 2 reaction system. The time scales for CO 2 sorption using nanowires are approximately 3 min and two orders magnitude faster compared to those obtained using lithium silicate powders with spherical morphologies and aggregates. Furthermore, Li 4 SiO 4 nanowire powders showed reversibility through sorption-desorption cycles indicating their suitability for CO 2 capture applications. All of the morphologies of Li 4 SiO 4 powders exhibited a double exponential behavior in the adsorption kinetics indicating two distinct time constants for kinetic and the mass transfer limited regimes.

  12. Use of radiotracers for studies of metal sorption behaviour

    International Nuclear Information System (INIS)

    McCubbin, D.; Leonard, K.S.

    1995-01-01

    Radiotracers provide a convenient tool to study the behaviour of metal ions and other contaminants in natural waters. Furthermore, the use of radiotracers in controlled laboratory experiments provides an ideal approach for investigating, in a systematic manner, the role of individual parameters on processes, at mass concentrations found in the environment. A simplistic procedure has been developed to produce a thorium radiotracer ( 234 Th), in a similar chemical form (non-acidic) to that of the aquatic medium under investigation, to determine the kinetics of sorption to marine particulate material. The benefit of this procedure is that the system is likely to be perturbed to a lesser extent by changes in pH and dissolved Th species following tracer addition. Results from filtering different tracer batches through membranes, to determine the sorption characteristics prior to use, indicate that the physico-chemical behaviour of individual batches was extremely variable. Not surprisingly, the amount of uptake immediately following tracer additions to solutions containing marine particulate material was also variable. It is suggested that the role of tracer may be underestimated if added in acid form. Nevertheless, having accounted for the initial sorption, the subsequent uptake between different batches was reasonably reproducible. The usefulness of radiotracers is discussed in the context of these observations

  13. Opposed piston linear compressor driven two-stage Stirling Cryocooler for cooling of IR sensors in space application

    Science.gov (United States)

    Bhojwani, Virendra; Inamdar, Asif; Lele, Mandar; Tendolkar, Mandar; Atrey, Milind; Bapat, Shridhar; Narayankhedkar, Kisan

    2017-04-01

    A two-stage Stirling Cryocooler has been developed and tested for cooling IR sensors in space application. The concept uses an opposed piston linear compressor to drive the two-stage Stirling expander. The configuration used a moving coil linear motor for the compressor as well as for the expander unit. Electrical phase difference of 80 degrees was maintained between the voltage waveforms supplied to the compressor motor and expander motor. The piston and displacer surface were coated with Rulon an anti-friction material to ensure oil less operation of the unit. The present article discusses analysis results, features of the cryocooler and experimental tests conducted on the developed unit. The two-stages of Cryo-cylinder and the expander units were manufactured from a single piece to ensure precise alignment between the two-stages. Flexure bearings were used to suspend the piston and displacer about its mean position. The objective of the work was to develop a two-stage Stirling cryocooler with 2 W at 120 K and 0.5 W at 60 K cooling capacity for the two-stages and input power of less than 120 W. The Cryocooler achieved a minimum temperature of 40.7 K at stage 2.

  14. Theoretical study of effect of working fluid on the performance of 77–100 K adsorption cryocooler

    International Nuclear Information System (INIS)

    Luo, B.J.; Wang, Z.L.; Yan, T.; Hong, G.T.; Li, Y.L.; Liang, J.T.

    2015-01-01

    Highlights: • Investigate the effects of nitrogen, argon and oxygen on the performance of adsorption cryocooler in the range 77–100 K. • A model of adsorption compressor with a two-stage adsorption compressor is constructed and optimized with genetic algorithm. • Working fluid has larger effects on the adsorption compressor than on the cold stage. • The best selection of working fluid depends on the operating parameters. - Abstract: The aim of this study is to investigate the effects of working fluid (nitrogen, argon and oxygen) on the performance of adsorption cryocooler in the range 77–100 K. A thermodynamic model of adsorption cryocooler with two-stage compressor has been constructed. The model is based on quasi-static conditions without considering the temperature profiles and pressure drops across the compressor. It is then analyzed with an optimization toolbox to determine the optimum operating conditions to obtain the optimum performance of adsorption cryocooler. The Coefficient of Performance (COP) for each working fluid in the range 77–100 K is obtained and compared. It is found that working fluid has larger effects on adsorption compressor than on cold stage, and the optimum selection of working fluid depends on the operating parameters

  15. Sorption behavior of neptunium on bentonite -- Effect of calcium ion on the sorption

    International Nuclear Information System (INIS)

    Kozai, Naofumi; Ohnuki, Toshihiko; Muraoka, Susumu

    1995-01-01

    The sorption behavior of neptunium on bentonite was studied with batch type sorption and desorption experiments over a pH range of 2 to 8. A series of parallel studies using Na-smectite, Ca-smectite and admixtures of Na-smectite and calcite quantified the capacity of Ca 2+ (which occurs in bentonite as an exchangeable cation of smectite and as a component of calcite) to inhibit the sorption of neptunium. The distribution coefficient (K d ) of neptunium for bentonite was constant from pH 2 to 7, while for pure Na-smectite K d increased below pH 5 due to specific sorption of neptunium on Na-smectite. Specific sorption was defined as occurring when neptunium could be desorbed by a strong acid (1 M HCl) but was stable in the presence of 1 M KCl. It was found that the quantity of neptunium sorbed on Na-smectite was inversely proportional to the concentration of Ca 2+ in solution, an effect most pronounced at pH 2+ limits the specific sorption capacity of Na-smectite for neptunium. Similarly, in the mixture of Na-smectite and calcite, sufficient Ca 2+ was solubilized to depress neptunium sorption. This investigation demonstrates that Ca 2+ contained in bentonite as exchangeable cation and released from calcite reduces the specific sorption of neptunium

  16. Sorption-desorption studies on tuff III. A continuation of studies with samples from Jackass Flats and Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Wolfsberg, K.; Aguilar, R.D.; Bayhurst, B.P.

    1981-05-01

    This report is the third in a series of reports describing studies of sorption and migration of radionuclides in tuff. The investigations were extended to lithologies of tuff not previously studied. Continuing experiments with uranium, plutonium, and americium are described. The dependence of sorption on the concentration of the sorbing element and on the solution-to-solid ratio was investigated for a number of nuclides and two lithologies. A circulating system was designed for measuring sorption ratios. Values obtained from this system, batch measurements, and column elutions are compared. Progress on measuring and controlling Eh is described

  17. Technetium sorption by stibnite from natural water

    International Nuclear Information System (INIS)

    Peretroukhine, V.; Sergeant, C.; Deves, G.; Poulain, S.; Vesvres, M.H.; Thomas, B.; Simonoff, M.

    2006-01-01

    The sorption of technetium by powdered and polished mineral stibnite Sb 2 S 3 has been investigated in simulated and natural underground waters from the Meuse/Haute-Marne region (France). The sorption by powdered stibnite has been found to be complete under both aerobic and anaerobic conditions in batch experiments. The sorption rate is higher in the absence of oxygen than under aerobic condition. Increasing the temperature from 30 C to 60 C results in a rise of the sorption rate by 9.1 and 27 times under anaerobic and aerobic conditions, respectively. The observed differences in sorption kinetics in the presence and in absence of oxygen are explained by the interaction of oxygen with sulfide ion in aerobic conditions and by the reduction of technetium(VII) by iron(II) and by other impurities present in natural water and in the mineral, and by the subsequent sorption of Tc(IV) on stibnite under anaerobic conditions. The sorption on a polished mineral surface resulted in the formation of a technetium film, probably Tc 2 S 7 , with a thickness of 1-3 μg Tc/cm 2 pH 3-6 and 4-12 μg Tc/cm 2 at 9-12. The simultaneous formation of stibnite colloids with adsorbed technetium occurs at pH 9-12. The study of the technetium film on the mineral by proton induced X-ray emission analysis showed it to be at least one order of magnitude thinner on the SiO 2 impurities than on the main Sb 2 S 3 component and the iron impurities. (orig.)

  18. Prediction and validation of diffusion coefficients in a model drug delivery system using microsecond atomistic molecular dynamics simulation and vapour sorption analysis.

    Science.gov (United States)

    Forrey, Christopher; Saylor, David M; Silverstein, Joshua S; Douglas, Jack F; Davis, Eric M; Elabd, Yossef A

    2014-10-14

    Diffusion of small to medium sized molecules in polymeric medical device materials underlies a broad range of public health concerns related to unintended leaching from or uptake into implantable medical devices. However, obtaining accurate diffusion coefficients for such systems at physiological temperature represents a formidable challenge, both experimentally and computationally. While molecular dynamics simulation has been used to accurately predict the diffusion coefficients, D, of a handful of gases in various polymers, this success has not been extended to molecules larger than gases, e.g., condensable vapours, liquids, and drugs. We present atomistic molecular dynamics simulation predictions of diffusion in a model drug eluting system that represent a dramatic improvement in accuracy compared to previous simulation predictions for comparable systems. We find that, for simulations of insufficient duration, sub-diffusive dynamics can lead to dramatic over-prediction of D. We present useful metrics for monitoring the extent of sub-diffusive dynamics and explore how these metrics correlate to error in D. We also identify a relationship between diffusion and fast dynamics in our system, which may serve as a means to more rapidly predict diffusion in slowly diffusing systems. Our work provides important precedent and essential insights for utilizing atomistic molecular dynamics simulations to predict diffusion coefficients of small to medium sized molecules in condensed soft matter systems.

  19. Characterization of nanoporous shales with gas sorption

    Science.gov (United States)

    Joewondo, N.; Prasad, M.

    2017-12-01

    The understanding of the fluid flow in porous media requires the knowledge of the pore system involved. Fluid flow in fine grained shales falls under different regime than transport regime in conventional reservoir due to the different average pore sizes in the two materials; the average pore diameter of conventional sandstones is on the micrometer scale, while of shales can be as small as several nanometers. Mercury intrusion porosimetry is normally used to characterize the pores of conventional reservoir, however with increasingly small pores, the injection pressure required to imbibe the pores becomes infinitely large due to surface tension. Characterization of pores can be expressed by a pore size distribution (PSD) plot, which reflects distribution of pore volume or surface area with respect to pore size. For the case of nanoporous materials, the surface area, which serves as the interface between the rock matrix and fluid, becomes increasingly large and important. Physisorption of gas has been extensively studied as a method of nanoporous solid characterization (particularly for the application of catalysis, metal organic frameworks, etc). The PSD is obtained by matching the experimental result to the calculated theoretical result (using Density Functional Theory (DFT), a quantum mechanics based modelling method for molecular scale interactions). We present the challenges and experimental result of Nitrogen and CO2 gas sorption on shales with various mineralogy and the interpreted PSD obtained by DFT method. Our result shows significant surface area contributed by the nanopores of shales, hence the importance of surface area measurements for the characterization of shales.

  20. Sorption of cesium in intact rock

    International Nuclear Information System (INIS)

    Puukko, E.

    2014-04-01

    The mass distribution coefficient K d is used in performance assessment (PA) to describe sorption of a radionuclide on rock. The R d is determined using crushed rock which causes uncertainty in converting the R d values to K d values for intact rock. This work describes a method to determine the equilibrium of sorption on intact rock. The rock types of the planned Olkiluoto waste disposal site were T-series mica gneiss (T-MGN), T-series tonalite granodiorite granite gneiss (T-TGG), P-series tonalite granodiorite granite gneiss (P-TGG) and pegmatitic granite (PGR). These rocks contain different amount of biotite which is the main sorbing mineral. The sorption of cesium on intact rock slices was studied by applying an electrical field to speed up migration of cesium into the rock. Cesium is in the solution as a noncomplex cation Cs + and it is sorbed by ion exchange. The tracer used in the experiments was 134 Cs. The experimental sorption on the intact rock is compared with values calculated using the in house cation exchange sorption model (HYRL model) in PHREEQC program. The observed sorption on T-MGN and T-TGG rocks was close to the calculated values. Two PGR samples were from a depth of 70 m and three samples were from a depth of 150 m. Cesium sorbed more than predicted on the two 70 m PGR samples. The sorption of Cs on the three 150 m PGR samples was small which was consistent with the calculations. The pegmatitic granite PGR has the smallest content of biotite of the four rock types. In the case of P-TGG rock the observed values of sorption were only half of the calculated values. Two kind of slices were cut from P-TGG drill core. The slices were against and to the direction of the foliation of the biotite rims. The sorption of cesium on P-TGG rock was same in both cases. The results indicated that there was no effect of the directions of the electric field and the foliation of biotite in the P-TGG rock. (orig.)

  1. Sorption of radionuclides by tertiary clays

    International Nuclear Information System (INIS)

    Wagner, J.F.; Czurda, K.A.

    1990-01-01

    The sorption capacity of different clay types for some metals (Co, Cs, Sr and Zn), occurring as common radionuclides in radioactive waste deposits, had been analysed by a static (batch technique) and a dynamic method (percolation tests, in which the driving force is a hydraulic gradient). Sorption capacity generally increased with an increasing pH of solution. A decrease of sorption capacity had been observed in the order Zn > Cs ≥ Co > Sr for the batch and Cs > Zn > Sr > Co for the percolation tests. Clay marls showed a distinctly higher sorption respectively retention capacity as pure clays. Sorption capacity depends on solution parameters like type and concentration of radionuclide, pH, salt concentration, etc., and on rock parameters like mineral content (e.g. swelling clay minerals and carbonates), organic material, rock pH, micro fabric, etc. A third parameter of great influence is the contact time between clay and solution. The adsorption isotherms reflect two different adsorption mechanisms: a very rapid adsorption (a few minutes) on the external surfaces of clay minerals and a slow adsorption process (weeks and longer), due to the diffusion of metal ions into the interlayer space of clay minerals. 12 refs., 9 figs., 1 tab

  2. Moisture sorption of Thai red curry powder

    Directory of Open Access Journals (Sweden)

    Sudathip Inchuen

    2009-12-01

    Full Text Available Moisture sorption study was conducted on Thai red curry powder prepared by two different drying methods, viz. microwave and hot-air drying. Moisture sorption isotherms of the red curry powder at 30 C and water activity in the range of 0.113-0.970 were determined by a static gravimetric method. The isotherms exhibited Type III behaviour. The moisture sorption data were fitted to several sorption models and a non-linear regression analysis method was used to evaluate the constants of the sorption equations. The fit was evaluated using the coefficient of determination (R2, the reduced chi-square (2 and the root mean square error (RMSE. The GAB model followed by the Lewiski-3 model gave the best fit to the experimental data. The monolayer moisture content, taken as the safe minimum moisture level in the red curry powder, was determined using the BET equation and was found to range between 0.080 - 0.085 gram water per gram dry matter.

  3. An Investigation of Certain Thermodynamic Losses in Miniature Cryocoolers

    Science.gov (United States)

    2007-05-02

    system Channel Measurement Parameter Sensor Gain Offset 1 Pressure in Volume A Endevco 2.408 bar/V 6.0206 bar 2 Pressure in Volume C Druck 200...1.9677 bar/V 15.444 bar 3 N/C 4 Pressure in compressor body Druck 820 6.0046 bar/V 8.3174 bar 5 Piston Position Sch’ LVDT 2.0884 mm/V -5.5968 mm...probe (courtesy of Prof. Moriyoshi). Left: 3D view showing two fine thermocouples are in a cross configuration. Right: Side elevation Results

  4. Heat cascading regenerative sorption heat pump

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1995-01-01

    A simple heat cascading regenerative sorption heat pump process with rejected or waste heat from a higher temperature chemisorption circuit (HTCC) powering a lower temperature physisorption circuit (LTPC) which provides a 30% total improvement over simple regenerative physisorption compression heat pumps when ammonia is both the chemisorbate and physisorbate, and a total improvement of 50% or more for LTPC having two pressure stages. The HTCC contains ammonia and a chemisorbent therefor contained in a plurality of canisters, a condenser-evaporator-radiator system, and a heater, operatively connected together. The LTPC contains ammonia and a physisorbent therefor contained in a plurality of compressors, a condenser-evaporator-radiator system, operatively connected together. A closed heat transfer circuit (CHTC) is provided which contains a flowing heat transfer liquid (FHTL) in thermal communication with each canister and each compressor for cascading heat from the HTCC to the LTPC. Heat is regenerated within the LTPC by transferring heat from one compressor to another. In one embodiment the regeneration is performed by another CHTC containing another FHTL in thermal communication with each compressor. In another embodiment the HTCC powers a lower temperature ammonia water absorption circuit (LTAWAC) which contains a generator-absorber system containing the absorbent, and a condenser-evaporator-radiator system, operatively connected together. The absorbent is water or an absorbent aqueous solution. A CHTC is provided which contains a FHTL in thermal communication with the generator for cascading heat from the HTCC to the LTAWAC. Heat is regenerated within the LTAWAC by transferring heat from the generator to the absorber. The chemical composition of the chemisorbent is different than the chemical composition of the physisorbent, and the absorbent. The chemical composition of the FHTL is different than the chemisorbent, the physisorbent, the absorbent, and ammonia.

  5. PILCs for trapping phosphorus in a heavy duty engine exhaust system : An experimental evaluation of the phosphorus sorption capability of different clay materials

    OpenAIRE

    Kvarned, Anders

    2016-01-01

    In order to fulfil the requirements in the EURO VI standard, regulating emissions from heavy duty vehicles, the exhaust aftertreatment system needs to maintain its efficiency for at least seven years or 700 000 km. In diesel applications the diesel oxidation catalyst (DOC) is located closest to the engine and is thus the most vulnerable to poisoning contaminants, such as phosphorus originating from fuel and oil additives, which deactivates the catalyst. An idea to reduce the impact from phosp...

  6. Methodology of Accelerated Life-Time Tests For Stirling-Type "Bae-Co"-Made Cryocoolers Against Displacer-Blockage by Cryo-Pollutant Deposits

    National Research Council Canada - National Science Library

    Getmanits, Vladimir

    2000-01-01

    ...: The contractor will investigate techniques for accelerated testing of cryocooler technology. During this phase of the effort the contractor will perform a detailed design of the equipment needed to conduct accelerated testing...

  7. Influence of smectite hydration and swelling on atrazine sorption behavior.

    Science.gov (United States)

    Chappell, Mark A; Laird, David A; Thompson, Michael L; Li, Hui; Teppen, Brian J; Aggarwal, Vaneet; Johnston, Cliff T; Boyd, Stephen A

    2005-05-01

    Smectites, clay minerals commonly found in soils and sediments, vary widely in their ability to adsorb organic chemicals. Recent research has demonstrated the importance of surface charge density and properties of exchangeable cations in controlling the affinity of smectites for organic molecules. In this study, we induced hysteresis in the crystalline swelling of smectites to test the hypothesis that the extent of crystalline swelling (or interlayer hydration status) has a large influence on the ability of smectites to adsorb atrazine from aqueous systems. Air-dried K-saturated Panther Creek (PC) smectite swelled less (d(001) = 1.38 nm) than never-dried K-PC (d(001) = 1.7 nm) when rehydrated in 20 mM KCl. Correspondingly, the air-dried-rehydrated K-PC had an order of magnitude greater affinity for atrazine relative to the never-dried K-PC. Both air-dried-rehydrated and never-dried Ca-PC expanded to approximately 2.0 nm in 10 mM CaCl2 and both samples had similar affinities for atrazine that were slightly lower than that of never-dried K-PC. The importance of interlayer hydration status in controlling sorption affinity was confirmed by molecular modeling, which revealed much greater interaction between interlayer water molecules and atrazine in a three-layer hydrate relative to a one-layer hydrate. The entropy change on moving atrazine from a fully hydrated state in the bulk solution to a partially hydrated state in the smectite interlayers is believed to be a major factor influencing sorption affinity. In an application test, choice of background solution (20 mM KCl versus 10 mM CaCl2) and air-drying treatments significantly affected atrazine sorption affinities for three-smectitic soils; however, the trends were not consistent with those observed for the reference smectite. Further, extending the initial rehydration time from 24 to 240 h (prior to adding atrazine) significantly decreased the soil's sorption affinity for atrazine. We conclude that interlayer

  8. Differences in sorption behavior of the herbicide 4-chloro-2-methylphenoxyacetic acid on artificial soils as a function of soil pre-aging.

    Science.gov (United States)

    Waldner, Georg; Friesl-Hanl, Wolfgang; Haberhauer, Georg; Gerzabek, Martin H

    The sorption behavior of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) to three different artificial soil mixtures was investigated. Artificial soils serve as model systems for improving understanding of sorption phenomena. The soils consisted of quartz, ferrihydrite, illite, montmorillonite, and charcoal. In a previous study, several selected mixtures had been inoculated with organic matter, and microbial aging (incubation) had been performed for different periods of time (3, 12, and 18 months) before conducting the sorption experiments. The effect of this pre-incubation time on the sorption behavior was determined. Interaction of MCPA with soil surfaces was monitored by aqueous phase sorption experiments, using high-performance liquid chromatography/ultraviolet and in selected cases Fourier-transformed infrared spectroscopy. The sorption behavior showed large differences between differently aged soils; Freundlich and linear sorption model fits (with sorption constants K f , 1/ n exponents, and K d values, respectively) were given for pH = 3 and the unbuffered pH of ∼7. The largest extent of sorption from diluted solutions was found on the surfaces with a pre-incubation time of 3 months. Sorption increased at acidic pH values. Regarding the influence of aging of artificial soils, the following conclusions were drawn: young artificial soils exhibit stronger sorption at lower concentrations, with a larger K f value than aged soils. A correlation with organic carbon content was not confirmed. Thus, the sorption characteristics of the soils are more influenced by the aging of the organic carbon than by the organic carbon content itself.

  9. Sorption behaviour of radioactive technetium in soils

    International Nuclear Information System (INIS)

    Xia Deying

    1996-01-01

    The sorption behaviour of technetium in different soils has been studied by batch experiments under aerobic conditions. The soil samples have been taken to study the characteristics and to derive the pH-Eh values. In addition, the activated carbon and reduced iron powder have been selected as additives to the JAERI sand according to the former research work, so that the technetium sorption behaviour in the artificial soils can be studied under similar conditions. The experimental results show that all these soil samples except for the gluey soil have a very small distribution coefficient for Tc, while the artificial soils have a very large distribution coefficient for Tc. Besides, for artificial soils, the distribution coefficient (R d ) values will become larger and larger when more additive is added and more contact time is allowed. The physico-chemical fixation processes and possible sorption modes have been discussed as well

  10. Sorption of Europium in zirconium silicate

    International Nuclear Information System (INIS)

    Garcia R, G.

    2004-01-01

    Some minerals have the property of sipping radioactive metals in solution, that it takes advantage to manufacture contention barriers that are placed in the repositories of nuclear wastes. The more recent investigations are focused in the development of new technologies guided to the sorption of alpha emissors on minerals which avoid their dispersion in the environment. In an effort to contribute to the understanding of this type of properties, some studies of sorption of Europium III are presented like homologous of the americium, on the surface of zirconium silicate (ZrSiO 4 ). In this work the results of sorption experiences are presented as well as the interpretation of the phenomena of the formation of species in the surface of the zirconium silicate. (Author)

  11. Sorption of radioactive technetium on pyrrhotine

    International Nuclear Information System (INIS)

    Shen, D.; Fan, X.H.; Su, X.G.; Zeng, J.S.; Dong, Y.

    2002-01-01

    The sorption behavior of technetium on pyrrhotine was studied with batch experiments and diluted sulfuric acid (less than 2.88 mol/l) was used to dissolve the technetium adsorbed on pyrrhotine. A significant sorption of technetium on pyrrhotine was observed under aerobic and anaerobic conditions, and the sorption on the mineral was supposed to be due to the reduction of TcO 4 - to insoluble TcO 2 x nH 2 O. Sorbed technetium on the mineral could be desorbed by diluted sulfuric acid. The maximum desorption ratio under aerobic conditions was much higher than that of under anaerobic conditions, meanwhile, the desorption rates under anaerobic conditions were higher than that of under aerobic conditions in the initial stage of the experiments. (author)

  12. Water sorption and transport in dry crispy bread crust

    NARCIS (Netherlands)

    Meinders, M.B.J.; Nieuwenhuijzen, van N.H.; Tromp, R.H.; Hamer, R.J.; Vliet, van T.

    2010-01-01

    Water sorption and dynamical properties of bread crust have been studied using gravimetric sorption experiments. Water uptake and loss were followed while relative humidity (RH) was stepwise in- or decreased (isotherm experiment) or varied between two adjusted values (oscillatory experiment).

  13. The sorption of acids in cellular side of apple pressing

    International Nuclear Information System (INIS)

    Asoev, M.G.; Mukhiddinov, Z.K.

    1994-01-01

    Equilibrium swell of sample refuse after separation of water is use for study of sorption of hydrochloric acid. Quantity adsorb acids set a price to difference her concentration before and after equilibrium sorption

  14. Molecular simulation of polycyclic aromatic hydrocarbon sorption to black carbon

    NARCIS (Netherlands)

    Haftka, J.J.H.; Parsons, J.R.; Govers, H.A.J.

    2009-01-01

    Strong sorption of hydrophobic organic contaminants to soot or black carbon (BC) is an important environmental process limiting the bioremediation potential of contaminated soils and sediments. Reliable methods to predict BC sorption coefficients for organic contaminants are therefore required. A

  15. On the derivation of a sorption database

    International Nuclear Information System (INIS)

    Ewart, F.T.; Haworth, A.; Wisbey, S.J.

    1992-01-01

    The safety arguments in support of many radioactive waste repository concepts are heavily dependent on the existence of a sorption reaction. Such a reaction will, in the near field, reduce the magnitude of the release of a number of hazardous radionuclides so that their release to the geosphere is dispersed in time. In the geosphere, the sorption reactions provide a mechanism whereby the migration of the elements released from the repository is retarded and the radioisotopes then subsequently decay. The processes involved in sorption cannot in many cases be satisfactorily represented in thermodynamic terms such as are employed in the description of dissolution and precipitation. Experiments that investigate these reactions are not easy to perform. The sorption parameters that are obtained experimentally for the near field relate, in the UK case, to sorption on to a cementitious surface. These surfaces, since they consist substantially of calcium hydroxide or calcium silicate hydrates, control the aqueous chemistry, do not permit pH changes to be made and limit the range of concentrations of sorbate that may be used. In the far field, on the other hand, the surfaces are not in general so active with respect to the solution chemistry and data can be obtained across a wide spectrum of aqueous chemistries. These data, although they may be useful in testing and parameterizing models, may not have validity under field conditions since the minerals will, inevitably, react to the changes in water chemistry, over geological timescales. The uncertainties in the experimental data are, for many elements and solids, balanced by a reasonable agreement between workers in the values of the parameters used to describe sorption. 22 refs., 1 fig., 1 tab

  16. Sorption Properties of Some Romanian Gingerbread

    Directory of Open Access Journals (Sweden)

    Tulbure Anca

    2014-06-01

    Full Text Available Water activity of gingerbread is very important for keeping the product freshness and shelf life. Water activity is influenced by composition, water content and temperature. The water content of gingerbread could vary according with storage condition. i.e. rH. 11 gingerbread samples were analysed. The water content and water activity lies between 7.0 and 12.6% and respectively 0.590 and 0.715. The sorption isotherms were determined at 30°C by gravimetric method. The moisture sorption is influenced by composition, especially sweeteners and humectants. Honey and invert sugar have the same impact on gingerbread higroscopicity.

  17. Sorption of radionuclides on hard rocks

    International Nuclear Information System (INIS)

    Berry, J.A.; Bourke, P.J.; Green, A.; Littleboy, A.K.

    1987-09-01

    Methods for measuring sorption on hard rocks, particularly of strontium, caesium, neptunium and americium on Darley Dale sandstone and Welsh slate have been investigated. The methods tried included batch tests with crushed rock and tests of simultaneous diffusion and convection with sorption on intact rock. High pressures (800m H 2 O) were used in the convective tests to pump water quickly through the rock samples and to measure high sorptivities in times shorter than those needed in the diffusive methods with intact samples. (author)

  18. A Sorption Hysteresis Model For Cellulosic Materials

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Damkilde, Lars

    2006-01-01

    The equilibrium concentration of adsorbed water in cellulosic materials is dependent on the history of the variations of vapor pressure in the ambient air, i.e. sorption hysteresis. Existing models to describe this phenomenon such as the independent domain theory have numerical drawbacks and....../or imply accounting for the entire history variations of every material point. This paper presents a sorption hysteresis model based on a state formulation and expressed in closed-form solutions, which makes it suitable for implementation into a numerical method....

  19. Sorption of natural uranium by algerian bentonite

    International Nuclear Information System (INIS)

    Megouda, N.; Kadi, H.; Hamla, M.S.; Brahimi, H.

    2004-01-01

    Full text.Batch sorption experiments have been used to assess the sorption behaviour of uranium onto natural and drilling bentonites. The operating parameters (pH, aolis-liquid ratio, particle size, time and initial uranium concentration) influenced the rate of adsorption. The distribution coefficient (Kd) range values at equilibrium time are 45.95-1079.26 ml/g and 32.81-463053 ml/g for the drilling and natural bentonites respectively. The equilibrium isotherms show that the data correlate with both Freundlich and Langmuir models

  20. Interactions among K+-Ca2+ exchange, sorption of m-dinitrobenzene, and smectite quasicrystal dynamics.

    Science.gov (United States)

    Chatterjee, Ritushree; Laird, David A; Thompson, Michael L

    2008-12-15

    The fate of organic contaminants in soils and sediments is influenced by sorption of the compounds to surfaces of soil materials. We investigated the interaction among sorption of an organic compound, cation exchange reactions, and both the size and swelling of smectite quasicrystals. Two reference smectites that vary in location and amount of layer charge, SPV (a Wyoming bentonite) and SAz-1 were initially Ca- and K-saturated and then equilibrated with mixed 0.01 M KCl and 0.005 M CaCl2 salt solutions both with and without the presence of 200 mg L(-1) m-dinitrobenzene (m-DNB). In general, sorption of m-DNB increased with the amount of K+ in the system for both clays, and the SPV sorbed more m-DNB than the SAz-1. Sorption of m-DNB increased the preference of Ca-SPV for K+ relative to Ca2+ but had little effect on K+-Ca2+ selectivity for K-SPV. Selectivity for K+ relative to Ca2+ was slightly higher for both K-SAz-1 and Ca-SAz-1 in the presence of m-DNB than in its absence. Distinct hysteresis loops were observed for the K+-Ca2+ cation exchange reactions for both clays, and the legacy of having been initially Ca- or K-saturated influenced sorption of m-DNB by SPV but had little effect for SAz-1. Suspension X-ray diffraction was used to measure changes in d-spacing and the relative thickness of smectite quasicrystals during the cation exchange and m-DNB sorption reactions. The results suggest that interactions among cation exchange and organic sorption reactions are controlled byan inherently hysteretic complex feedback process that is regulated by changes in the size and extent of swelling of smectite quasicrystals.

  1. Sorption behaviour of radiocaesium in soils from various regions of Libya and Sweden

    International Nuclear Information System (INIS)

    Shenber, Mohamed Ahmed.

    1992-01-01

    In the last years the interest of zeolite minerals has increased. Some of them have been tested as caesium binding agents in both animals and in soil-plant systems. The sorption capacity of zeolites was high, and the experimental results showed that the zeolite materials have a considerable potential as a caesium binding agent. A significant reduction reduction in the plant uptake of 134 Cs, maximally by a factor of 8, was obtained in the experiments. The sorption characteristics of 134 Cs on soils from various regions of Libya and Sweden were studied, using batch techniques. The influence of soil parameters, contact time, and various concentrations of Cs + , K + and NH 4 + in the solution on the sorption ratio (R s -value) for 134 Cs were determined by using 134 Cs as a tracer. Important parameters influencing the sorption were clay content, pH, and the concentration of cations, in particular that of K + and NH 4 + , which compete with Cs + for the sorption sites. The conditions influencing the exchangeability of 134 Cs sorbed in different soil types were studied in desorption experiments. The exchangeability of caesium was determined by extraction with 1 N Ba Cl 2 and 1 N NH 4 Cl. The results showed that divalent Ba 2+ was much less effective than the monovalent NH 4 + in exchanging 134 Cs from the sorption sites in the soils. Increasing the equilibration time and drying the soils reduced the exchangeability of 134 Cs in most of the soils, especially the fraction exchangeable with NH 4 + . Correlations were found between the radiocaesium transfer factor for plant uptake, clay content, and sorption ratio. Simple mathematical models were used to estimate the transfer factors for radiocaesium to wheat on soils of interest, for which no uptake data are available. 31 refs, 1 fig, 2 tabs

  2. A sorption model for alkalis in cement-based materials - Correlations with solubility and electrokinetic properties

    Science.gov (United States)

    Henocq, Pierre

    2017-06-01

    In cement-based materials, radionuclide uptake is mainly controlled by calcium silicate hydrates (C-S-H). This work presents an approach for defining a unique set of parameters of a surface complexation model describing the sorption behavior of alkali ions on the C-S-H surface. Alkali sorption processes are modeled using the CD-MUSIC function integrated in the Phreeqc V.3.0.6 geochemical code. Parameterization of the model was performed based on (1) retention, (2) zeta potential, and (3) solubility experimental data from the literature. This paper shows an application of this model to sodium ions. It was shown that retention, i.e. surface interactions, and solubility are closely related, and a consistent sorption model for radionuclides in cement-based materials requires a coupled surface interaction/chemical equilibrium model. In case of C-S-H with low calcium-to-silicon ratios, sorption of sodium ions on the C-S-H surface strongly influences the chemical equilibrium of the C-S-H + NaCl system by significantly increasing the aqueous calcium concentration. The close relationship between sorption and chemical equilibrium was successfully illustrated by modeling the effect of the solid-to-liquid ratio on the calcium content in solution in the case of C-S-H + NaCl systems.

  3. Microcrystallography, high-pressure cryocooling and BioSAXS at MacCHESS

    Energy Technology Data Exchange (ETDEWEB)

    Englich, Ulrich, E-mail: ue22@cornell.edu; Kriksunov, Irina A. [MacCHESS (Macromolecular Diffraction Facility at CHESS), Cornell University, Ithaca, NY 14853 (United States); Cerione, Richard A. [MacCHESS (Macromolecular Diffraction Facility at CHESS), Cornell University, Ithaca, NY 14853 (United States); Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853 (United States); Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Cook, Michael J.; Gillilan, Richard [MacCHESS (Macromolecular Diffraction Facility at CHESS), Cornell University, Ithaca, NY 14853 (United States); Gruner, Sol M. [Field of Biophysics, Cornell University, Ithaca, NY 14853 (United States); Physics Department, Cornell University, Ithaca, NY 14853 (United States); Huang, Qingqui; Kim, Chae Un; Miller, William; Nielsen, Soren; Schuller, David; Smith, Scott; Szebenyi, Doletha M. E. [MacCHESS (Macromolecular Diffraction Facility at CHESS), Cornell University, Ithaca, NY 14853 (United States)

    2011-01-01

    Three research initiatives pursued by the Macromolecular Diffraction Facility at the Cornell High Energy Synchrotron Source (MacCHESS) are presented. The Macromolecular Diffraction Facility at the Cornell High Energy Synchrotron Source (MacCHESS) is a national research resource supported by the National Center for Research Resources of the US National Institutes of Health. MacCHESS is pursuing several research initiatives designed to benefit both CHESS users and the wider structural biology community. Three initiatives are presented in further detail: microcrystallography, which aims to improve the collection of diffraction data from crystals a few micrometers across, or small well diffracting regions of inhomogeneous crystals, so as to obtain high-resolution structures; pressure cryocooling, which can stabilize transient structures and reduce lattice damage during the cooling process; and BioSAXS (small-angle X-ray scattering on biological solutions), which can extract molecular shape and other structural information from macromolecules in solution.

  4. Three-stage linear, split-Stirling cryocooler for 1 to 2K magnetic cold stage

    International Nuclear Information System (INIS)

    Longsworth, R.C.

    1993-08-01

    A long-life, linear, high efficiency 8K split Stirling cycle cryocooler was designed, built, and tested. The refrigerator is designed for cooling a 50 mW, 1.5K magnetic cold stage. Dual opposed piston compressors are driven by moving-coil linear motors. The three stage expander, although not completed, is also driven by a linear motor and is designed to produce 1 SW at 60K, 4W at 16K, and 1.2W at 8K. The cold regenerator employs a parallel gap construction for high efficiency. The key technology areas addressed include warm and cold flexible suspension bearings and a new cold regenerator geometry for high efficiency at 8K

  5. Comparative simulation of Stirling and Sibling cycle cryocoolers with two codes

    International Nuclear Information System (INIS)

    Mitchell, M.P.; Wilson, K.J.; Bauwens, L.

    1989-01-01

    The authors present a comparative analysis of Stirling and Sibling Cycle cryocoolers conducted with two different computer simulation codes. One code (CRYOWEISS) performs an initial analysis on the assumption of isothermal conditions in the machines and adjusts that result with decoupled loss calculations. The other code (MS*2) models fluid flows and heat transfers more realistically but ignores significant loss mechanisms, including flow friction and heat conduction through the metal of the machines. Surprisingly, MS*2 is less optimistic about performance of all machines even though it ignores losses that are modelled by CRYOWEISS. Comparison between constant-bore Stirling and Sibling machines shows that their performance is generally comparable over a range of temperatures, pressures and operating speeds. No machine was consistently superior or inferior according to both codes over the whole range of conditions studied

  6. High efficiency 40 K single-stage Stirling-type pulse tube cryocooler

    Science.gov (United States)

    Wu, X. L.; Chen, L. B.; Pan, C. Z.; Cui, C.; Wang, J. J.; Zhou, Y.

    2017-12-01

    A high efficiency single-stage Stirling-type coaxial pulse tube cryocooler (SPTC) operating at around 40 K has been designed, built and tested. The double-inlet and the inertance tubes together with the gas reservoir were adopted as the phase shifters. Under the conditions of 2.5 MPa charging pressure and 30 Hz operating frequency, the prototype has achieved a no-load temperature of 23.8 K with 330 W of electric input power at a rejection temperature of 279 K. When the input power increases to 400 W, it can achieve a cooling capacity of 4.7 W/40 K while rejecting heat at 279 K yielding an efficiency of 7.02% relative to Carnot. It achieves a cooling capacity of 5 W/40 K with an input power of 450 W. It takes 10 minutes for the SPTC to cool to its no-load temperature of 40 K from 295 K.

  7. Sorption Properties of Aerogel in Liquid Nitrogen

    Science.gov (United States)

    Johnson, Wesley L.

    2006-01-01

    Aerogel products are now available as insulation materials of the future. The Cryogenics Test Laboratory at the NASA Kennedy Space Center is developing aerogel-based thermal insulation systems for space launch applications. Aerogel beads (Cabot Nanogel ) and aerogel blankets (Aspen Aerogels Spaceloft ) have outstanding ambient pressure thermal performance that makes them useful for applications where sealing is not possible. Aerogel beads are open-celled silicone dioxide and have tiny pores that run throughout the body of the bead. It has also recently been discovered that aerogel beads can be used as a filtering device for aqueous compounds at room temperature. With their hydrophobic covering, the beads absorb any non-polar substance and they can be chemically altered to absorb hot gases. The combination of the absorption and cryogenic insulating properties of aerogel beads have never been studied together. For future cryogenic insulation applications, it is crucial to know how the beads react while immersed in cryogenic liquids, most notably liquid nitrogen. Aerogel beads in loose-fill situation and aerogel blankets with composite fiber structure have been tested for absorption properties. Depending on the type of aerogel used and the preparation, preliminary results show the material can absorb up to seven times its own weight of liquid nitrogen, corresponding to a volumetric ratio of 0.70 (unit volume nitrogen per unit volume aerogel). These tests allow for an estimate on how much insulation is needed in certain situations. The theory behind the different processes of sorption is necessary for a better understanding of the preparation of the beads before they are used in an insulation system.

  8. The sorption behaviour of 99Tc on activated carbon

    International Nuclear Information System (INIS)

    Xia Deying; Zeng Jishu

    2004-01-01

    The sorption behaviour of 99 Tc on apricot-pit activated carbon with batch experiment is studied. The influence of such factors as sorbent particle size, temperature, pH value on sorption ratio, and the Freundlich sorption isotherms are reported in this paper. (author)

  9. Suitability of Moshi Pumice for Phosphorus Sorption in Constructed ...

    African Journals Online (AJOL)

    The study of Moshi Pumice's phosphorus sorption behaviours and properties was carried out in laboratory scale where by 1-2 mm, 2-4 mm and 4-8 mm grains were tested using batch experiments. The results show that Moshi Pumice has high phosphorus sorption capacity. The sorption capacity for the Moshi Pumice was ...

  10. Phosphorus sorption in relation to soil grain size and geochemical ...

    African Journals Online (AJOL)

    By using stepwise regression, the combination of Al, Fe, clay and Ca predicted more than 94% of the variation in the P sorption capacity of soils samples from Simiyu and Kagera basins. These four soil properties, which are strongly related to P sorption, could therefore be used as quick tests for predicting the P sorption ...

  11. Sorption of Heterocyclic Organic Compounds to Multiwalled Carbon Nanotubes.

    Science.gov (United States)

    Metzelder, Florian; Funck, Matin; Schmidt, Torsten C

    2018-01-16

    Sorption is an important natural and technical process. Sorption coefficients are typically determined in batch experiments, but this may be challenging for weakly sorbing compounds. An alternative method enabling analysis of those compounds is column chromatography. A column packed with the sorbent is used and sorption data are determined by relating sorbate retention to that of a nonretarded tracer. In this study, column chromatography was applied for the first time to study sorption of previously hardly investigated heterocyclic organic compounds to multiwalled carbon nanotubes (MWCNTs). Sorption data for these compounds are very limited in literature, and weak sorption is expected from predictions. Deuterium oxide was used as nonretarded tracer. Sorption isotherms were well described by the Freundlich model and data showed reasonable agreement with predicted values. Sorption was exothermic and physisorption was observed. H-bonding may contribute to overall sorption, which is supported by reduced sorption with increasing ionic strength due to blocking of functional groups. Lowering pH reduced sorption of ionizable compounds, due to electrostatic repulsion at pH 3 where sorbent as well as sorbates were positively charged. Overall, column chromatography was successfully used to study sorption of heterocyclic compounds to MWCNTs and could be applied for other carbon-based sorbents.

  12. Attenuation of polychlorinated biphenyl sorption to charcoal by humic acids

    NARCIS (Netherlands)

    Koelmans, A.A.; Meulman, B.; Meijer, T.; Jonker, M.T.O.

    2009-01-01

    Strong sorption to black carbon may limit the environmental risks of organic pollutants, but interactions with cosorbing humic acid (HA) may interfere. We studied the attenuative effect of HA additions on the sorption of polychlorinated biphenyls (PCBs) to a charcoal. "Intrinsic" sorption to

  13. Sorption mechanisms of perfluorinated compounds on carbon nanotubes

    International Nuclear Information System (INIS)

    Deng Shubo; Zhang Qiaoying; Nie Yao; Wei Haoran; Wang Bin; Huang Jun; Yu Gang; Xing Baoshan

    2012-01-01

    Sorption of perfluorinated compounds (PFCs) on carbon nanotubes (CNTs) is critical for understanding their subsequent transport and fate in aqueous environments, but the sorption mechanisms remain largely unknown. In this study, the sorption of six PFCs on CNTs increased with increasing C-F chain length when they had a same functional group, and the CNTs with hydroxyl and carboxyl groups had much lower adsorbed amount than the pristine CNTs, indicating that hydrophobic interaction dominated the sorption of PFCs on the CNTs. Electrostatic repulsion suppressed the sorption of PFCs on the CNTs, resulting in the lower sorption with increasing pH. Hydrogen bonding interaction was negligible. The hydrophobic C-F chains can be closely adsorbed on the CNTs surface in parallel to the axis or along the curvature, making it impossible to form micelles on the CNT surface, leading to the lower sorption than other adsorbents. Highlights: ► Sorption capacities of PFOA on different CNTs are less than that on activated carbon and resins. ► Hydrophobic interaction is principally involved in the sorption of PFCs on CNTs. ► Electrostatic repulsion suppresses the sorption of PFCs on CNTs. - Hydrophobic interaction dominated the sorption of perfluorinated compounds on carbon nanotubes, while electrostatic repulsion suppressed their sorption.

  14. Review of sorption and diffusion data for SR 97

    Energy Technology Data Exchange (ETDEWEB)

    Stenhouse, M. [Monitor Scientific, LLC, Denver, CO (United States)

    2000-12-01

    The approach of SKB in providing K{sub d} values for transport calculations for SR 97 has been to provide what is termed a reasonable estimate for the sorption of each radioelement on granitic rock under saline and non-saline groundwater conditions, as well as a corresponding uncertainty range based on available experimental data. Typical treatments of input data for K{sub d} values in the past have been to provide 'realistic' and 'conservative' estimates of K{sub d} values, but the precise meaning of 'conservative' has often been vague and inconsistent. Thus, the approach, to provide a reasonable estimate supported by an uncertainty range for saline and non-saline conditions, is a different but reasonable methodology for the treatment of K{sub d} values. Carbol and Engkvist have updated the review of sorption data and associated recommendations by Albinsson, provided for the SKB 91 safety assessment. The update consisted of an examination of additional experimental sorption data published since the initial review in 1991, with modification of the recommendations of Albinsson where warranted. The new data are not presented, although references are provided. Bruno and Duro reviewed the recommendations of Carbol and Engkvist, and were able to provide additional experimental data from the literature, although no experimental details were provided concerning new sorption data cited. Based on their review, Bruno and Duro made some reasonable recommendations. Although not taken into account in the database in Andersson, the effect of such recommendations, particularly for Sr, will be covered by uncertainty range calculations. Given the importance of K{sub d} as a retardation parameter, the uncertainty ranges appear relatively narrow. There is a danger that the ranges will be treated as absolute, when frequently they are based generally on a small number of experimental data or even a lack of experimental data for the rock water systems being

  15. Effects of Citrate and Arginine on Sorption of Nickel to Yazd Sepiolite and Calcite

    Directory of Open Access Journals (Sweden)

    Ahmadreza Sheikhhosseini

    2017-03-01

    Full Text Available Introduction: Pollution of soil and water environment by release of heavy metals is of great concerns of the last decades. Sorption of heavy metals by low cost materials is considered as an inexpensive and efficient method used for removal of heavy metals from soil-water systems. The presence of different ligands with various complexing abilities can change the sorption properties of heavy metals and their fate in the environment as well. In order to assess the effect of citrate and arginine as natural organic ligands in soil environment, in a batch study we investigated the effects of these ligands on equilibrium sorption of nickel to sepiolite and calcite minerals and also kinetics of Ni sorption by these minerals. Materials and Methods: Minerals used in this study included sepiolite from Yazd (Iran and pure calcite (Analytical grade, Merck, Germany. Sepiolite was purified, saturated with Ca using 0.5 M CaCl2, powdered in a mortar and sieved by non-metal 230 mesh standard wire sieve. For equilibrium sorption study, in a 50-mL polyethylene centrifuge tube,0.3 g sample of each mineral was suspended in 30 mL of a 0.01 M CaCl2 solution containing 0, 5, 10, 20, 40, 60, 80 and 100 mg L-1 Ni (NiCl2 and containing zero (as control or 0.1mmol L-1 citrate or arginine ligands. The applied concentrationsfor each ligand can naturally occur in soils. Preparedtubes were shaken (180±2 rpm, 25±1oC for 24 h using an orbital shaker and centrifuged (4000×g for 10 min and the supernatants were analyzed for Ni concentration using an atomic absorption spectrophotometer (AAnalyst 200 Perkin-Elmer at a wavelength of 232 nm and a detection limit of 0.05 mg L-1. The quantity of Ni retained by each mineral at equilibrium was calculated using equation qe = (Ci - CeV/W where qe was the amount of nickel retained by mineral surface at equilibrium. Ci and Ce were the initial and the equilibrium concentrations (mg L-1 of Ni, respectively, V was the volume (L of the solution

  16. Surface complexation modelling applied to the sorption of nickel on silica

    International Nuclear Information System (INIS)

    Olin, M.

    1995-10-01

    The modelling based on a mechanistic approach, of a sorption experiment is presented in the report. The system chosen for experiments (nickel + silica) is modelled by using literature values for some parameters, the remainder being fitted by existing experimental results. All calculations are performed by HYDRAQL, a model planned especially for surface complexation modelling. Allmost all the calculations are made by using the Triple-Layer Model (TLM) approach, which appeared to be sufficiently flexible for the silica system. The report includes a short description of mechanistic sorption models, input data, experimental results and modelling results (mostly graphical presentations). (13 refs., 40 figs., 4 tabs.)

  17. Hydration and sorption characteristics of a polyfunctional weak-base anion exchanger after the sorption of vanillin and ethylvanillin

    Science.gov (United States)

    Rodionova, D. O.; Voronyuk, I. V.; Eliseeva, T. V.

    2016-07-01

    Features of the sorption of substituted aromatic aldehydes by a weak-base anion exchanger under equilibrium conditions are investigated using vanillin and ethylvanillin as examples. Analysis of the sorption isotherms of carbonyl compounds at different temperatures allows us to calculate the equilibrium characteristics of their sorption and assess the entropy and enthalpy contributions to the energy of the process. Hydration characteristics of the macroporous weak-base anion exchanger before and after the sorption of aromatic aldehydes are compared.

  18. Sorption of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) to synthetic resins.

    Science.gov (United States)

    Bi, Erping; Haderlein, Stefan B; Schmidt, Torsten C

    2005-10-01

    Methyl tert-butyl ether (MTBE) is a widely used gasoline oxygenate. Contamination of MTBE and its major degradation product tert-butyl alcohol (TBA) in groundwater and surface water has received great attention. However, sorption affinity and sorption mechanisms of MTBE and TBA to synthetic resins, which can be potentially used in removal of these contaminants from water, in passive sampling, or in enrichment of bacteria, have not been studied systemically. In this study, kinetic and equilibrium sorption experiments (single solute and binary mixtures) on four synthetic resins were conducted. The sorption affinity of the investigated sorbents for MTBE and TBA decreases in the order Ambersorb 563>Optipore L493>Amberlite XAD4>Amberlite XAD7, and all show higher sorption affinity for MTBE than for TBA. Binary experiments with o-xylene, a major compound of gasoline as co-contaminant, imply that all resins preferentially sorb o-xylene over MTBE or TBA, i.e., there is sorption competition. In the equilibrium aqueous concentration (Ceq) range (0.1-139.0 mg/L for MTBE, and 0.01-48.4 mg/L for TBA), experimental and modeling results as well as sorbent characteristics indicate that micropore filling and/or some other type of adsorption process (e.g., adsorption to specific sites of high sorption potential at low concentrations) rather than partitioning were the dominant sorption mechanisms. Optipore L493 has favourable sorption and desorption characteristics, and is a suitable sorbent, e.g., in bacteria enrichment or passive sampling for moderately polar compounds. However, for highly polar compounds such as TBA, Ambersorb 563 might be a better choice, especially in water treatment.

  19. Isothermal titration calorimetry of sorption processes. A promising approach

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Norbert; Foerstendorf, Harald [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Drobot, B. [Technische Univ. Dresden (Germany); Fahmy, Karim [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Biophysics; Reder, Christian

    2017-06-01

    As a consequence of nuclear waste disintegration heat, elevated temperatures in the near field may influence radionuclide retention significantly. However, there is a nearly complete lack of spectroscopic investigations of sorption processes at elevated temperatures. In addition, experimental data on free Gibbs energy (Δ{sub R}G), enthalpy (Δ{sub R}H) and entropy (Δ{sub R}S) of reactions of most radionuclides including fission products such as {sup 79}Se are sparse. Using the Se(IV)/hematite system, we show that microcalorimetry can provide these thermodynamic parameters with high accuracy and in a manner that allows studying various radionuclides.

  20. A suggested approach toward measuring sorption and applying sorption data to repository performance assessment

    International Nuclear Information System (INIS)

    Rundberg, R.S.

    1991-01-01

    The sorption of radioisotopes in relation to geologic disposal of radioactive wastes is discussed. Properties of the radioactive materials, rocks, and minerals, and the chemistry involved are described. 51 refs., 12 figs. CBS

  1. 20 K continuous cycle sorption coolers for the Planck flight mission

    Science.gov (United States)

    Bhandari, P.; Prina, M.; Bowman, R. C., Jr.; Paine, C.; Pearson, D.; Nash, A.

    2003-01-01

    In this paper we present the level of maturity of the hydrogen sorption cooler technology at JPL by describing the design and how it has been validated at the subsystem and system levels. In addition, we will describe how such systems could be advantageously used for other space missions with similar needs and cooler attributes.

  2. Sorption of fission nuclides on model milk components. II. Sorption of radiostrontium on hydroxyapatite in milk and whey

    International Nuclear Information System (INIS)

    Rosskopfova, O.; Kopunec, R.; Matel, L.; Macasek, F.

    1999-01-01

    In this work the whey was chosen as a model solution of liquid phase for sorption study of strontium on hydroxyapatite. The whey was obtained using two methods - ultracentrifugation and precipitation of casein. The sorption was studied at a different pH and at a different concentration of calcium. The sorption of strontium on hydroxyapatite from milk was studied, too. (authors)

  3. Gas Sorption, Diffusion, and Permeation in Nafion

    KAUST Repository

    Mukaddam, Mohsin Ahmed; Litwiller, Eric; Pinnau, Ingo

    2015-01-01

    The gas permeability of dry Nafion films was determined at 2 atm and 35 °C for He, H2, N2, O2, CO2, CH4, C2H6, and C3H8. In addition, gas sorption isotherms were determined by gravimetric and barometric techniques as a function of pressure up to 20

  4. Sorption of radiocalcium on human hair

    International Nuclear Information System (INIS)

    Rakovic, M.; Pilecka, N.

    1987-01-01

    The sorption of 45 Ca on hair from a 45 CaCl 2 solution (2.5x10 -3 mol l -1 ) was studied. The calcium amounts sorbed in 1 min to 5 h range between 0.8 and 7.2% with respect to the originally present calcium in hair. (author) 3 refs

  5. Sorption of methanol in alkali exchange zeolites

    NARCIS (Netherlands)

    Rep, M.; Rep, M.; Corma, Avelino; Palomares, A.E.; Palomares gimeno, A.E.; van Ommen, J.G.; Lefferts, Leonardus; Lercher, J.A.

    2000-01-01

    Metal cation methanol sorption complexes in MFI (ZSM5), MOR and X have been studied by in situ i.r. spectroscopy in order to understand the nature of interactions of methanol in the molecular sieve pores. The results show that (a) a freely vibrating hydroxy and methyl group of methanol exist on

  6. Radionuclide sorption database for Swiss safety assessment

    International Nuclear Information System (INIS)

    McKinley, I.G.; Hadermann, J.

    1984-10-01

    Recommended sorption data for use in transport models for a Swiss High-Level Waste repository are presented. The models used in 'Project Gewaehr 1985' assume linear sorption isotherms and require elemental partition coefficient (Kd) data. On the basis of a literature search 'realistic' Kd data for 22 elements have been selected for weathered crystalline rock and sediments in contact with a reducing groundwater and also sediments with a less reducing groundwater. In an appendix sorption data for 28 elements on bentonite backfill are given. These data are supplemented with 'conservative' estimates taken to represent minimum reasonable values. Available data are discussed for each element clearly exhibiting (i) the large gaps in knowledge, (ii) their unbalanced distribution between different elements and, hence, (iii) the need for further experiments in the laboratory, the field and analogue studies. An overview of the theoretical concepts of sorption, experimental methodology and data interpretation is given in order to put the values into context. General problem areas are identified. (Auth.)

  7. Theory of molecular hydrogen sorption for hydrogen storage

    Science.gov (United States)

    Zhang, Shengbai

    2011-03-01

    Molecular hydrogen (H2) sorption has the advantage of fast kinetics and high reversibility. However, the binding strength is often too weak to be operative at near room temperatures. Research into such hydrogen sorption materials has branched into the study of pure van der Waals (vdW) physisorption and that of weak chemisorption (known to exist in the so-called Kubas complexes). In either case, however, theoretical tools to describe such weak interactions are underdeveloped with error bars that often exceed the strength of the interaction itself. We have used quantum-chemistry (QC) based approaches to benchmark the various available DFT methods for four classes of weak chemisorption systems [Sun et al., Phys. Rev. B 82, 073401 (2010)]. These involve complexes containing Li, Ca, Sc, and Ti with increased strength of H2 binding from predominantly vdW to mostly Kubas-like. The study reveals that most of the DFT functionals within the generalized gradient approximation underestimate the binding energy, oppose to overestimating it. The functionals that are easy to use yet yielding results reasonably close to those of accurate QC are the PBE and PW91. I will also discuss the effort of implementing vdW interaction into the currently available density functional methods [Sun, J. Chem. Phys. 129, 154102 (2008)]. The rationale is that while the true vdW is an electron-electron correlation, a DFT plus classical dispersion approach may be too simple and unnecessary within the DFT. A local pseudopotential approach has been developed to account for the core part of the polarizability of the elements. Applications to a number of benchmark systems yield good agreement with QC calculations. The application of this method and the QC methods to vdW hydrogen binding will also be discussed. Work supported by DOE/BES and DOE/EERE Hydrogen Sorption Center of Excellence under RPI subcontracts No. J30546/J90336.

  8. Neptunium(V) sorption on quartz and albite in aqueous suspension

    International Nuclear Information System (INIS)

    Kohler, M.; Leckie, J.O.

    1991-10-01

    The behavior of neptunium in the subsurface environment is of interest since neptunium isotopes are included in nuclear waste. Previous work investigated the sorption behavior of Np onto α-Fe 2 O 3 (hematite), an accessory mineral of the Yucca Mountain repository. The work reported herein involves the much more abundant silicate minerals quartz and albite, and is a logical continuation of the ongoing task. In previous work increased sorption was observed in systems containing hematite and EDTA, a ligand which acts as a surrogate for organic complexing agents. In addition, increased partial pressures of CO 2 are common in many ground waters and the effects of carbonate on sorption of radionuclides have to be studied as well. At concentration levels of 10 -7 M, Np(V) does not adsorb strongly on quartz and albite up to pH values of approximately 9 at solid/solution ratios of 30 to 40 g/l. Significant adsorption (> 20%) occurs on both minerals only at pH > 9. Pretreatment of albite affects the sorption behavior of this mineral at pH > 9, possibly due to the formation of secondary mineral phases at the albite surface. EDTA does not adsorb on quartz at concentrations of 10 -6 M. In the presence of 50 μM EDTA, Np(V) sorption seems to be restricted. EDTA at the 10 -6 M level adsorbs onto albite to an appreciable degree at pH values 3 - is the predominant solution species

  9. New insights into the sorption mechanism of cadmium on red mud

    International Nuclear Information System (INIS)

    Luo Lei; Ma Chenyan; Ma Yibing; Zhang Shuzhen; Lv Jitao; Cui Mingqi

    2011-01-01

    Effectiveness and mechanism of cadmium (Cd) sorption on original, acidified and ball milling nano-particle red muds were investigated using batch sorption experiments, sequential extraction analysis and X-ray absorption near edge structure (XANES) spectroscopy. The maximum sorption capacity of Cd was 0.16, 0.19, and 0.21 mol/kg for the original, acidified, and nano-particle red muds at pH 6.5, respectively. Both acidification and ball-milling treatments significantly enhanced Cd sorption and facilitated transformation of Cd into less extractable fractions. The Cd L III -edge XANES analysis indicated the formation of inner-sphere complexes of Cd similar to XCdOH (X represents surface groups on red mud) on the red mud surfaces although outer-sphere complexes of Cd were the primary species. This work shed light on the potential application of red mud to remediate Cd-contaminated soils and illustrated the promising tool of XANES spectroscopy for speciation of multicomponent systems of environmental relevance. - Graphical abstract: Display Omitted Highlights: → Red mud has a strong affinity for Cd contaminants. → Ball-milling treatments significantly enhance Cd sorption on red mud. → Cadmium partially formed inner-sphere complexes on the red mud surfaces. → Red mud can be used to remediate Cd contaminated soils effectively. - Cadmium can be strongly sorbed and partially forms inner-sphere complexes on red mud.

  10. Kinetic studies on phosphorus sorption by selected soil amendments for septic tank effluent renovation.

    Science.gov (United States)

    Cheung, K C; Venkitachalam, T H

    2006-01-01

    A systematic kinetic study of phosphorus (P) sorption by various materials in the soil infiltration system of septic tanks was undertaken by following the time course of P sorption by sorbents in contact with various P solutions over periods up to 360 days. Uptake of P seemed to consist of two distinct stages. Initial uptake was very rapid and this phase was completed in 4 days or less. A slower removal stage followed for some materials over many months. Phosphorus sorption during the fast reaction stage appeared to be associated with the soluble Ca content of the materials. The fast reaction of calcareous materials accounted for the bulk (>70%) of the total P removed. Merribrook loamy sand exhibited the highest proportion of P sorption during the slow phase. It should be noted, however, that for solution P concentrations in the range found in typical effluents (approximately 20 mg L(-1)) the fast reaction phase seemed to be responsible for virtually all P removed. None of the six kinetic formulae examined possessed the sophistication and detail needed to portray accurately the time course of P sorption for all the sorbents investigated. The Elovich equation and the kinetic modification of the Freundlich isotherm expression appeared to provide a reasonable fit of the experimental data.

  11. Radionuclide sorption on crushed and intact granitic rock

    International Nuclear Information System (INIS)

    Eriksen, Tryggve E.; Locklund, Birgitta

    1989-05-01

    The specific surface areas and distribution ratios for sorption of 85 Sr, 137 Cs and 152 Eu were measured for crushed and intact granite rock. The experimental data can be accommodated by a sorption model encompassing sorption on outer and inner surface. It is clearly demonstrated that the time required to obtain reliable Kd-values for the sorption of strongly sorbing radionuclides like 152 Eu is very long due to solution depletion and slow diffusion into the rock. A combination of surface area measurements and batch sorption with small particles may therefore be preferable when studying strongly sorbing nuclides. (authors) (17 figs., 6 tabs.)

  12. Sorption and migration of neptunium in porous sedimentary materials

    International Nuclear Information System (INIS)

    Tanaka, Tadao; Mukai, Masayuki; Nakayama, Shinichi

    2005-01-01

    Column migration experiments of neptunium were conducted for porous sedimentary materials: coastal sand, tuffaceous sand, ando soil, reddish soil, yellowish soil and loess, and migration behavior, sorption mechanisms and chemical formation of Np were investigated. The migration behavior of Np in each material was much different each other, due to chemical formation in solution and/or sorption mechanism of Np. Mathematical models of different concepts were applied to the experimental results to interpret the sorption mechanism and the migration behavior. It can be concluded that both of instantaneous equilibrium sorption and sorption-desorption kinetics have to be considered to model the Np migration in sedimentary materials. (author)

  13. Sorption of niobium on boreal forest soil

    Energy Technology Data Exchange (ETDEWEB)

    Soederlund, Mervi; Hakanen, Martti; Lehto, Jukka [Helsinki Univ. (Finland). Lab. of Radiochemistry

    2015-07-01

    The sorption of niobium (Nb) was investigated on humus and mineral soil samples taken from various depths of a four-metre deep forest soil pit on Olkiluoto Island, southwestern Finland. Mass distribution coefficients, K{sub d}, were determined in batch sorption tests. The steady state of Nb sorption was observed in the mineral soil samples already after one week of equilibration, and sorption decreased with depth from a very high value of 185000 mL/g at 0.7 m to 54000 mL/g at 3.4 m. The reason behind this decrease is probably the tenfold reduction in the specific surface area of the soil at the same depth range. Distribution coefficients were clearly lower in the humus layer (1000 mL/g). The K{sub d} values determined in pure water at a pH range of 4.7-6.5 were at a high level (above 55000 mL/g), but decreased dramatically above pH 6.5, corresponding to the change in the major Nb species from the neutral Nb(OH){sub 5} to the low-sorbing anionic Nb(OH){sub 6}{sup -} and Nb(OH){sub 7}{sup 2-}. However, the K{sub d} values in the model soil solution were in the slightly alkaline range an order of magnitude higher than in pure water, which is probably caused by the formation of calcium niobate surface precipitate or electrostatic interaction between surface-sorbed calcium and solute Nb. Among nine soil constituent minerals kaolinite performed best in retaining Nb in both pure water and model soil solution at pH 8, whereas potassium feldspar showed the poorest sorption. The K{sub d} value for kaolinite was above 500000 mL/g in both solutions, while the respective potassium feldspar values were in the range of 120-220 mL/g.

  14. Sorption behaviour of perfluoroalkyl substances in soils.

    Science.gov (United States)

    Milinovic, Jelena; Lacorte, Silvia; Vidal, Miquel; Rigol, Anna

    2015-04-01

    The sorption behaviour of three perfluoroalkyl substances (PFASs), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonic acid (PFBS), was studied in six soils with contrasting characteristics, especially in the organic carbon content. Sorption isotherms were obtained by equilibrating the soil samples with 0.01 mol L(-1) CaCl2 solutions spiked with increasing concentrations of the target PFAS. The sorption reversibility of PFASs was also tested for some of the samples. Liquid chromatography coupled to tandem mass spectrometry was used to quantify the target PFASs in the solutions. Both the Freundlich and linear models were appropriate to describe the sorption behaviour of PFASs in soils, and enabled us to derive solid-liquid distribution coefficients (Kd) for each compound in each soil. Kd values increased from 19 to 295 mL g(-1) for PFOS, from 2.2 to 38 mL g(-1) for PFOA and from 0.4 to 6.8 mL g(-1) for PFBS, and were positively correlated with the organic carbon content of the soil. KOC values obtained from the correlations were 710, 96 and 17 mL g(-1) for PFOS, PFOA and PFBS, respectively. Whereas Kd values decreased in the sequence PFOS>PFOA>PFBS, desorption yields were lower than 13% for PFOS, from 24 to 58% for PFOA, and from 32 to 60% for PFBS. This shows that the physicochemical characteristics of PFASs, basically their hydrophobicity, controlled their sorption behaviour in soils, with PFOS being the most irreversibly sorbed PFAS. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Modeling Fission Product Sorption in Graphite Structures

    International Nuclear Information System (INIS)

    Szlufarska, Izabela; Morgan, Dane; Allen, Todd

    2013-01-01

    The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high-temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission products

  16. Novel “open-sorption pipe” reactor for solar thermal energy storage

    International Nuclear Information System (INIS)

    Aydin, Devrim; Casey, Sean P.; Chen, Xiangjie; Riffat, Saffa

    2016-01-01

    Highlights: • A novel ‘open sorption pipe’ heat storage was experimentally investigated. • Effect of absolute moisture levels on heat storage performance was analyzed. • Hygrothermal-cyclic performances of Zeolite 13X and vermiculite–calcium chloride were compared. • Vermiculite–calcium chloride has more durable performance than Zeolite at 80 °C regeneration temperature. • Sorption pipe system using vermiculite–calcium chloride provides energy storage density of 290 kW h/m"3. - Abstract: In the last decade sorption heat storage systems are gaining attention due to their high energy storage density and long term heat storage potential. Sorption reactor development is vital for future progress of these systems however little has done on this topic. In this study, a novel sorption pipe reactor for solar thermal energy storage is developed and experimentally investigated to fulfill this gap. The modular heat storage system consists of sorption pipe units with an internal perforated diffuser pipe network and the sorption material filled in between. Vermiculite–calcium chloride composite material was employed as the sorbent in the reactor and its thermal performance was investigated under different inlet air humidity levels. It was found that, a fourfold increase of absolute humidity difference of air led to approximately 2.3 times boost in average power output from 313 W to 730 W and an 8.8 times boost of average exergy from 4.8 W to 42.3 W. According to the testing results, each of three sorption pipes can provide an average air temperature lift of 24.1 °C over 20 h corresponding to a system total energy storage capacity of 25.5 kW h and energy storage density of 290 kW h/m"3. Within the study, vermiculite–calcium chloride performance was also compared with the widely investigated Zeolite 13X. Vermiculite–calcium chloride showed a good cyclic ability at regeneration temperature of 80 °C with a steadier thermal performance than Zeolite

  17. SORPTION OF Au(III BY Saccharomyces cerevisiae BIOMASS

    Directory of Open Access Journals (Sweden)

    Amaria Amaria

    2010-07-01

    Full Text Available Au(III sorption by S. cerevisiae biomass extracted from beer waste industry was investigated. Experimentally, the sorption was conducted in batch method. This research involved five steps: 1 identification the functional groups present in the S. cerevisiae biomass by infrared spectroscopic technique, 2 determination of optimum pH, 3 determination of the sorption capacity and energy, 4 determination of the sorption type by conducting desorption of sorbed Au(III using specific eluents having different desorption capacity such as H2O (van der Waals, KNO3 (ion exchange, HNO3 (hydrogen bond, and tiourea (coordination bond, 5 determination of effective eluents in Au(III desorption by partial desorption of sorbed Au(III using thiourea, NaCN and KI. The remaining Au(III concentrations in filtrate were analyzed using Atomic Absorption Spectrophotometer. The results showed that: 1 Functional groups of S. cerevisiae biomass that involved in the sorption processes were hydroxyl (-OH, carboxylate (-COO- and amine (-NH2, 2 maximum sorption was occurred at pH 4, equal to 98.19% of total sorption, 3 The sorption capacity of biomass was 133.33 mg/g (6.7682E-04 mol/g and was involved sorption energy 23.03 kJ mol-1, 4 Sorption type was dominated by coordination bond, 5 NaCN was effective eluent to strip Au(III close to 100%.   Keywords: sorption, desorption, S. cerevisiae biomass, Au(III

  18. The 4 K Stirling cryocooler demonstration. Final report No. 8, 1 May 1990-30 April 1992

    International Nuclear Information System (INIS)

    Stacy, W.D.

    1992-09-01

    This report briefly summarizes the results and conclusions from an SBIR program intended to demonstrate an innovative Stirling cycle cryocooler concept for efficiently lifting heat from 4 K. Refrigeration at 4 K, a temperature useful for superconductors and sensitive instruments, is beyond the reach of conventional regenerative thermodynamic cycles due to the rapid loss of regenerator matrix heat capacity at temperatures below about 20 K. To overcome this fundamental limit, the cryocooler developed under this program integrated three unique features: recuperative regeneration between the displacement gas flow streams of two independent Stirling cycles operating at a 180 degree phase angle, tailored distortion of the two expander volume waveforms from sinusoidal to perfectly match the instantaneous regenerator heat flux from the two cycles and thereby unload the regenerator, and metal diaphragm working volumes to promote near isothermal expansion and compression processes. Use of diaphragms also provides unlimited operating life potential and eliminates bearings and high precision running seals. A phase 1 proof-of-principle experiment demonstrated that counterflow regenerator operation between 77 K and 4 K increases regenerator effectiveness by minimizing metal temperature transient cycling. In phase 2, a detailed design package for a breadboard cryocooler was completed. Fabrication techniques were successfully developed for manufacturing high precision miniature parallel plate recuperators, and samples were produced and inspected. Process development for fabricating suitably flat diaphragms proved more difficult and expensive than anticipated, and construction of the cryocooler was suspended at a completion level of approximately 75%. Subsequent development efforts on other projects have successfully overcome diaphragm fabrication difficulties

  19. Lanthanides and actinides sorption on to alumina with simple organic ligands. Thermodynamic and spectroscopic approaches

    International Nuclear Information System (INIS)

    Alliot, C.

    2003-01-01

    This work comes within studies of nuclear waste disposal. The sorption of radionuclide onto mineral is very important to understand their migration. So this work deals with the influence of ligands like oxalic, acetic and carbonic acids on lanthanides and actinides sorption onto alumina. Two complementary approaches were carried out: thermodynamic (determination of chemical reactions and associated constants). So we obtain a thermodynamic database for the ternary systems metal/ligand/alumina which we use to define the experimental conditions to observe by spectroscopy sorbed species. Then the identification of surface complexes was carried out using two spectroscopies, XPS and TRLIFS. (author)

  20. Sorption of long-lived radionuclides in clay and rock

    International Nuclear Information System (INIS)

    Allard, B.; Kipatsi, H.; Rydberg, J.

    1977-10-01

    The mechanism of sorption of water soluble species in the natural environment has been discussed. The radiochemical and radiobiological properties of the elements in spent nuclear fuel have been briefly discussed, and 14 of the radioactive products have been selected for studies of the sorption behaviour in contact with natural rock and clay minerals. These 14 elements are Sr, Zr, Tc, I, Cs, Ce, Nd, Eu, Ra, Th, U, Np, Pu and Am. From data available concerning composition and equilibria in natural subsoil waters two standard water compositions have been suggested for the laboratory measurements. Suitable concentrations of the radionuclides and experimental temperatures have been proposed. A batch technique has been used for determination of distribution coefficients for powdered solid materials. Measurements have been performed for all of the 14 elements with granite and bentonite/quartz mixture (10:90) with variation of water composition, nuclide concentration and temperature. Moreover, the effect of variation of the particle size has been studied for granite with Sr, Cs and Am, as well as the sorption in powdered granodiorite, chlorite and silt and on fresh and old rock surfaces (granite). The presence of organic components in bentonite has been confirmed and a preliminary complex formation study with these organics has been performed. An estimation of the valencestate of the actinides U, Np and Pu has been suggested using reasonable assumptions regarding the hydrolysis of the actinides and the presence of Fe(IIE/Fe(IE in natural waters. Using measured or calculated distribution coefficients and considering the chemical properties of the natural water system, relevant retention factors of the radionuclides have been proposed. (author)

  1. Using fluorescent dyes as proxies to study herbicide removal by sorption in buffer zones.

    Science.gov (United States)

    Dollinger, Jeanne; Dagès, Cécile; Voltz, Marc

    2017-04-01

    The performance of buffer zones for removing pesticides from runoff water varies greatly according to landscape settings, hydraulic regime, and system design. Evaluating the performance of buffers for a range of pesticides and environmental conditions can be very expensive. Recent studies suggested that the fluorescent dyes uranine and sulforhodamine B could be used as cost-effective surrogates of herbicides to evaluate buffer performance. However, while transformation mechanisms in buffers have been extensively documented, sorption processes of both dyes have rarely been investigated. In this study, we measured the adsorption, desorption, and kinetic sorption coefficients of uranine and sulforhodamine B for a diverse range of buffer zone materials (soils, litters, plants) and compared the adsorption coefficients (Kd) to those of selected herbicides. We also compared the global sorption capacity of 6 ditches, characterized by varying proportions of the aforementioned materials, between both dyes and a set of four herbicides using the sorption-induced pesticide retention indicator (SPRI). We found that both the individual Kd of uranine for the diverse buffer materials and the global sorption capacity of the ditches are equivalent to those of the herbicides diuron, isoproturon, and metolachlor. The Kd of sulforhodamine B on plants and soils are equivalent to those of glyphosate, and the global sorption capacities of the ditches are equivalent for both molecules. Hence, we demonstrate for the first time that uranine can be used as a proxy of moderately hydrophobic herbicides to evaluate the performance of buffer systems, whereas sulforhodamine B can serve as a proxy for more strongly sorbing herbicides.

  2. Modelling Ni diffusion in bentonite using different sorption models

    International Nuclear Information System (INIS)

    Pfingsten, W.; Baeyens, B.; Bradbury, M.

    2010-01-01

    Document available in extended abstract form only. An important component of the multi barrier disposal concept for a radioactive waste repository is the bentonite backfill surrounding the canisters containing vitrified high-level waste and spent fuel located in the tunnels deep within the chosen host rock. The effectiveness of the compacted bentonite barrier is such that calculations have indicated that many radionuclides have decayed to insignificant levels before having diffused through the thickness of bentonite. These calculations are performed using the simple Kd sorption concept in which the values are taken from batch type experiments performed on dispersed systems performed for a single metal at a time, usually at trace concentrations. However, in such complex systems many radionuclides, inactive metal contaminants/ground water components may be simultaneously present in the aqueous phase at a range of concentrations varying with time during the temporal evolution of the repository system. An important aspect influencing the sorption of any radioactive metal under a set of given geochemical conditions is its competition with other metals present, and how this may vary as a function of concentration. Competitive sorption effects are not currently included in safety assessments and are thus an issue which needs to be addressed. Here we provide some first estimates of the potential influence of competitive sorption effects on the migration of radioactive metals through compacted bentonite as a function of their concentration and the concentration of competing metals. Ni(II) and Fe(II) were chosen as possible competing cations since their concentration levels are expected to have values greater than trace levels and effects might be maximal and canister corrosion represents a permanent Fe source at the bentonite interface which could influence bivalent radionuclide diffusion. The modelling of the Ni(II) diffusion/sorption has been carried out using three

  3. Sorption Behavior of CO2 and CH4 of Glassy Polymeric Membranes and Analytical Discussion of Partial Immobilization Model

    Directory of Open Access Journals (Sweden)

    M. Mahdavian

    2007-06-01

    Full Text Available Among various reported membrane-based gas separation processes, the best explanation is generally achieved by the solution-diffusion model. The main factors in this model are the solubility and diffusivity of permeationcomponents through the membrane. The prediction of permeability and diffusivity in multicomponent gas permeation as well as the separation evaluation equilibrium and kinetic interactions requires a proper explanation of sorption and diffusion phenomena in the polymer matrix. Investigation made by various researchers in this area shows that the equilibrium interaction (sorption step plays the key role in determining diffusion and permeation in multicomponent system. Therefore, the proper description of sorption behaviour of gas mixture in the polymer is an essential task. The dual-mode sorption (Langmuir-Henry is usually used for the description of equilibrium isotherm of gases in glassy polymers based on this model; the diffusive behaviour of the system is subsequently analyzed by the partial immobilization model. In this study, the equilibrium sorption of CO2/CH4 mixture in various polymers was modelled using the experimental data available in the literature. The differences in the mechanism of adsorption for CO2 and CH4 were analyzed by considering variations in mode of sorption for each adsorbed component at different pressures. By introducing a new adsorption parameter, P50/50, (the pressure at which the portion of two modes in sorption are equal the contribution of each adsorbed component in occupying Langmuir sites was evaluated. The results indicate that the relative significance of sorption mode for each component is a function of pressure and it is different for various polymers.

  4. Influence of iron redox transformations on plutonium sorption to sediments

    Energy Technology Data Exchange (ETDEWEB)

    Hixon, A.E.; Powell, B.A. [Environmental Engineering and Earth Sciences, Clemson Univ., Clemson, SC (United States); Hu, Y.J.; Nitsche, H. [Dept. of Chemistry, Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab., Berkeley, CA (United States); Kaplan, D.I. [Savannah River National Lab., Aiken, SC (United States); Kukkadapu, R.K.; Qafoku, O. [Pacific Northwest National Lab., Richland, WA (United States)

    2010-07-01

    Plutonium subsurface mobility is primarily controlled by its oxidation state, which in turn is loosely coupled to the oxidation state of iron in the system. Experiments were conducted to examine the effect of sediment iron mineral composition and oxidation state on plutonium sorption and reduction. A pH 6.3 vadose zone sediment containing iron oxides and iron-containing phyllosilicates was treated with various complexants (ammonium oxalate) and reductants (hydroxylamine hydrochloride and dithionite-citrate-bicarbonate (DCB)) to selectively leach and/or reduce iron oxide and phyllosilicate/clay Fe(III). {sup 57}Fe-Moessbauer spectroscopy was used to identify initial iron mineral composition of the sediment and monitor dissolution and reduction of iron oxides and reduction of phyllosilicate Fe(III). {sup 57}Fe-Moessbauer spectroscopy showed that the Fe-mineral composition of the untreated sediment is: 25-30% hematite, 60-65% small-particle/Al-goethite, and < 10% Fe(III) in phyllosilicate; there was no detectable Fe(II). Upon reduction with a strong chemical reductant (dithionite-citrate-bicarbonate buffer), much of the hematite and goethite was removed. Partial reduction of phyllosilicate Fe(III) was evident in the sediments subjected to DCB treatment. Sorption of Pu(V) was monitored over one week for the untreated and each of five treated sediment fractions. Plutonium oxidation state speciation in the aqueous and solid phases was monitored using solvent extraction, coprecipitation, and XANES. The rate of sorption appears to correlate with the fraction of Fe(II) in the sediment (untreated or treated). Pu(V) was the only oxidation state measured in the aqueous phase, irrespective of treatment, whereas Pu(IV) and much smaller amounts of Pu(V) and Pu(VI) were measured in the solid phase. Surface-mediated reduction of Pu(V) to Pu(IV) occurred in treated and untreated sediment samples; Pu(V) remained on untreated sediment surface for two days before reducing to Pu

  5. Influence of mineral characteristics on the retention of low molecular weight organic compounds: a batch sorption-desorption and ATR-FTIR study.

    Science.gov (United States)

    Yeasmin, Sabina; Singh, Balwant; Kookana, Rai S; Farrell, Mark; Sparks, Donald L; Johnston, Cliff T

    2014-10-15

    Batch experiments were conducted to evaluate the sorption-desorption behaviour of (14)C-labelled carboxylic acids (citric and oxalic) and amino acids (glutamic, alanine, phenylalanine and lysine) on pure minerals (kaolinite, illite, montmorillonite, ferrihydrite and goethite). The sorption experiments were complemented by ATR-FTIR spectroscopy to gain possible mechanistic insight into the organic acids-mineral interactions. In terms of charge, the organic solutes ranged from strongly negative (i.e., citric) to positively charged solutes (i.e., lysine); similarly the mineral phases also ranged from positively to negatively charged surfaces. In general, sorption of anionic carboxylic and glutamic acids was higher compared to the other compounds (except lysine). Cationic lysine showed a stronger affinity to permanently charged phyllosilicates than Fe oxides. The sorption of alanine and phenylalanine was consistently low for all minerals, with relatively higher sorption and lower desorption of phenylalanine than alanine. Overall, the role of carboxylic functional groups for the sorption and retention of these carboxylic and amino acids on Fe oxides (and kaolinite) and of amino group on 2:1 phyllosilicates was noticeable. Mineral properties (surface chemistry, specific surface area), chemistry of the organic compounds (pKa value, functional groups) and the equilibrium pH of the system together controlled the differences in sorption-desorption patterns. The results of this study aid to understand the effects of mineralogical and chemical factors that affect naturally occurring low molecular weight organic compounds sorption under field conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Phosphorus fractions and phosphorus sorption characteristics of freshwater sediments and their relationship to sediment composition

    Czech Academy of Sciences Publication Activity Database

    Borovec, Jakub; Hejzlar, Josef

    2001-01-01

    Roč. 151, č. 4 (2001), s. 687-703 ISSN 0003-9136 R&D Projects: GA ČR GA206/99/0028; GA ČR GA206/00/0063 Keywords : nutrients in aquatic systems * sorption/desorption of phosphorus Subject RIV: DA - Hydrology ; Limnology Impact factor: 1.186, year: 2001

  7. Kinetic and equilibrium study for the sorption of Pb(II) ions from ...

    African Journals Online (AJOL)

    Kinetic and equilibrium study for the sorption of Pb(II) ions from aqueous phase by water hyacinth ( Eichhornia crassipes ) ... Bulletin of the Chemical Society of Ethiopia ... Abstract. This paper reports the kinetic and equilibrium studies of Eichhornia crassipes root biomass as a biosorbent for Pb(II) ions from aqueous system.

  8. Isotherm, kinetic, and thermodynamic study of ciprofloxacin sorption on sediments.

    Science.gov (United States)

    Mutavdžić Pavlović, Dragana; Ćurković, Lidija; Grčić, Ivana; Šimić, Iva; Župan, Josip

    2017-04-01

    In this study, equilibrium isotherms, kinetics and thermodynamics of ciprofloxacin on seven sediments in a batch sorption process were examined. The effects of contact time, initial ciprofloxacin concentration, temperature and ionic strength on the sorption process were studied. The K d parameter from linear sorption model was determined by linear regression analysis, while the Freundlich and Dubinin-Radushkevich (D-R) sorption models were applied to describe the equilibrium isotherms by linear and nonlinear methods. The estimated K d values varied from 171 to 37,347 mL/g. The obtained values of E (free energy estimated from D-R isotherm model) were between 3.51 and 8.64 kJ/mol, which indicated a physical nature of ciprofloxacin sorption on studied sediments. According to obtained n values as measure of intensity of sorption estimate from Freundlich isotherm model (from 0.69 to 1.442), ciprofloxacin sorption on sediments can be categorized from poor to moderately difficult sorption characteristics. Kinetics data were best fitted by the pseudo-second-order model (R 2  > 0.999). Thermodynamic parameters including the Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were calculated to estimate the nature of ciprofloxacin sorption. Results suggested that sorption on sediments was a spontaneous exothermic process.

  9. Testosterone sorption and desorption: Effects of soil particle size

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Yong, E-mail: yqi01@unomaha.edu [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Zhang, Tian C. [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Ren, Yongzheng [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-08-30

    Graphical abstract: - Highlights: • Smaller soil particles have higher sorption and lower desorption rates. • The sorption capacity ranks as clay > silt > sand. • Small particles like clays have less potential for desorption. • Colloids (clays) have high potential to facilitate the transport of hormones in soil–water environments. - Abstract: Soils contain a wide range of particles of different diameters with different mobility during rainfall events. Effects of soil particles on sorption and desorption behaviors of steroid hormones have not been investigated. In this study, wet sieve washing and repeated sedimentation methods were used to fractionate the soils into five ranges. The sorption and desorption properties and related mechanisms of testosterone in batch reactors filled with fractionated soil particles were evaluated. Results of sorption and desorption kinetics indicate that small soil particles have higher sorption and lower desorption rates than that of big ones. Thermodynamic results show the sorption processes are spontaneous and exothermal. The sorption capacity ranks as clay > silt > sand, depending mainly on specific surface area and surface functional groups. The urea control test shows that hydrogen bonding contributes to testosterone sorption onto clay and silt but not on sand. Desorption tests indicate sorption is 36–65% irreversible from clay to sand. Clays have highest desorption hysteresis among these five soil fractions, indicating small particles like clays have less potential for desorption. The results provide indirect evidence on the colloid (clay)-facilitated transport of hormones (micro-pollutants) in soil environments.

  10. Neptunium(V) sorption onto kaolinite in the absence and presence of CO2

    International Nuclear Information System (INIS)

    Amayri, S.; Reich, Ta.; Reich, T.

    2005-01-01

    Full text of publication follows: The adsorption of heavy metals on clay minerals such as kaolinite is an important process that affects the migration and retardation of neptunium and other actinides in the geosphere. The sorption of Np(V) onto the reference clay mineral kaolinite KGa-1b was investigated both by batch experiments and EXAFS measurements. The aim of our study was to combine macroscopic studies (batch experiments) with microscopic techniques (EXAFS) to study the Np(V) speciation at the kaolinite surface. The batch experiments were done under relevant environmental conditions with Np(V) concentrations of 10 -11 and 10 -12 mol/L. Sorption samples were prepared in 0.1 mol/L NaClO 4 , 4 g/L kaolinite, pH 6.0 to 10.5, presence and absence of ambient CO 2 , and 60-h equilibration. The sorption curves for 10 -11 and 10 -12 mol/L Np(V) obtained in the presence and absence of CO 2 , respectively, show that the adsorption edge occurs at pH 8.5. The uptake of Np(V) by kaolinite strongly increased above pH 7.0 and reached its sorption maximum (70 %) at pH 9.0. Above pH 9.0, the amount of Np(V) sorbed onto kaolinite decreased and reached ca. 30 % at pH 10.5 due to the formation of Np(V) carbonato species in the aqueous solution. In the CO 2 -free system, the sorption of Np(V) increased continuously with pH until the sorption maximum of 100 % was reached at pH 10.5. The same sorption behavior was found in batch experiments in the CO 2 equilibrated system with Np concentrations ranging from 1 μmol/L to 10 μmol/L. EXAFS experiments on some of these batch samples indicated the formation of Np(V) carbonato species at the kaolinite surface at pH 9.0 where the uptake of Np(V) by kaolinite reaches its maximum [1]. [1] T. Reich, S. Amayri, Ta. Reich, J. Drebert, A. Jermolajev, P. Thoerle, N. Trautmann, C. Hennig, S. Sachs, Feasibility of EXAFS experiments at the Np L-edge to investigate neptunium sorption on kaolinite, Institut fuer Kernchemie, Universitaet Mainz, Annual

  11. Effect of natural organic materials on cadmium and neptunium sorption

    International Nuclear Information System (INIS)

    Kung, K.S.; Triay, I.R.

    1994-01-01

    In a batch sorption study of the effect of naturally occurring organic materials on the sorption of cadmium and neptunium on oxides and tuff surfaces, the model sorbents were synthetic goethite, boehmite, amorphous silicon oxides, and a crushed tuff material from Yucca Mountain, Nevada. An amino acid, 3-(3,4-dihydroxypheny)-DL-alanine (DOPA), and an aquatic-originated fulvic material, Nordic aquatic fulvic acid (NAFA), were used as model organic chemicals. Sorption isotherm results showed that DOPA sorption followed the order aluminum oxide > iron oxide > silicon oxide and that the amount of DOAP sorption for a given sorbent increased as the solution pH was raised. The sorption of cadmium and neptunium on the iron oxide was about ten times higher than that on the aluminum oxide. The sorption of cadmium and neptunium on natural tuff material was much lower than that on aluminum and iron oxides. The sorption of cadmium on iron and aluminum oxides was found to be influenced by the presence of DOPA, and increasing the amount of DOPA coating resulted in higher cadmium sorption on aluminum oxide. However, for iron oxide, cadmium sorption decreased with increasing DOPA concentration. The presence of the model organic materials DOPA and NAFA did not affect the sorption of neptunium on tuff material or on the iron and aluminum oxides. Spectroscopic results indicate that cadmium complexes strongly with DOPA. Therefore, the effect of the organic material, DOPA, on the cadmium sorption is readily observed. However, neptunium is possibly complexed weakly with organic material. Thus, DOPA and NAFA have little effect on neptunium sorption on all sorbents selected for study

  12. Europium sorption on zirconia at elevated temperatures: experimental study and modeling

    International Nuclear Information System (INIS)

    Eglizaud, N.; Catalette, H.

    2005-01-01

    Full text of publication follows: Direct disposal of spent nuclear fuel in deep underground repository is being considered by several countries. The waste package maintains an elevated temperature for thousands of years. As sorption is one of the main phenomenon limiting the dispersion of radionuclides in the environment, it has to be studied at elevated temperatures. Zirconia is an oxide produced by cladding oxidation which is suspected in the near field of a nuclear repository. It then could possibly be in contact with waste elements as Europium (III), the sorption of which is therefore studied on zirconia. Experiments were performed by the batch method at a solid/liquid ratio of 10 g.L-1. The sorption edges were recorded in the pH-range from 2 to 10 at 2.10 -5 mol.L -1 Eu(NO 3 ) 3 (I = 0.1 mol.L -1 KNO 3 ). An over-pressure device in an autoclave with an incorporated filtering system allowed the experiments, carbonate free, at 25 deg. C, 50 deg. C, 80 deg. C, 120 deg. C and 150 deg. C and in situ pH measurements. Filtrates were analyzed by the ICP-AES method. Sorption isotherms show an increase in the sorption phenomenon when the temperature raises. The half sorption pH decreases from 7 at 25 deg. C to 3,6 at 150 deg. C. The distribution coefficients that were obtained at elevated temperatures enriched the databases of integrated performance assessment codes. Raw data were modeled with the surface complexation theory using the double layer model (DLM). Several possible surface complexes were examined and discussed, taking into account aqueous hydrolyzed and precipitated species of Europium. A good agreement between experimental values and modeled isotherms was found at all studied temperatures. Results were consistent with a bidentate complex formed by Europium (III) on the zirconia surface. Associated formation constants were then determined with the geochemical computer code CHESS. (authors)

  13. Antimony sorption properties of chitosan - nano TiO2 composite beads

    International Nuclear Information System (INIS)

    Nishad, Padala Abdul; Bhaskarapillai, Anupkumar; Velmurugan, Sankaralingam

    2015-01-01

    Routine decontamination campaigns of nuclear reactors are generally effective in removing various radionuclides such as cobalt, caesium, etc., and bring down the radiation field. However, during some of the decontamination campaigns, the radiation field at some surfaces was seen to have actually gone up. This was found to be due to lack of removal of antimony isotopes by the regular ion exchange resins used, which subsequently deposited over out of core surfaces leading to increased radiation field on those surfaces. Thus there exists a need for efficient antimony removal system. We have synthesised nano titania impregnated - epichlorohydrin crosslinked chitosan beads, which were found to have high sorption capacity for antimony. The beads, which were synthesised in formats suitable for large scale (column mode) applications, were shown to be effective sorbent of antimony in both +3 and +5 oxidation states. The sorbent exhibited complete removal of antimony from its aqueous solutions of concentration ranging from 150 ppb to 120 ppm. In order to understand the sorption mechanism and to fine tune the bead composition, the effect of crosslinker concentration used during the synthesis on the swelling and sorption properties of the beads was investigated in detail. The variation effected significant changes in physical parameters such as bead diameter, swelling ratio, equilibrium water content and true wet density. Sorption capacity, unlike with regular resins, was found to increase with increase in crosslinker amount. The antimony sorption capacity of the crosslinked beads prepared by crosslinking 0.3 g uncrosslinked beads with 6.4 mmol epichlorohydrin (crosslinker) was 493 μmol/g. Non-crosslinked beads showed a capacity of 75 μmol/g, while the crosslinked beads made with the least amount of crosslinker (0.64 mmol per 0.3 g beads) showed a capacity of 133 μmol/g. These results indicate the possible involvement of the crosslinker in the sorption. (author)

  14. Modeling approaches of competitive sorption and transport of trace metals and metalloids in soils: a review.

    Science.gov (United States)

    Selim, H M; Zhang, Hua

    2013-01-01

    Competition among various heavy metal species for available adsorption sites on soil matrix surfaces can enhance the mobility of contaminants in the soil environment. Accurate predictions of the fate and behavior of heavy metals in soils and geologic media requires the understanding of the underlying competitive-sorption and transport processes. In this review, we present equilibrium and kinetic models for competitive heavy metal sorption and transport in soils. Several examples are summarized to illustrate the impact of competing ions on the reactivities and mobility of heavy metals in the soil-water environment. We demonstrate that equilibrium Freundlich approaches can be extended to account for competitive sorption of cations and anions with the incorporation of competition coefficients associated with each reaction. Furthermore, retention models of the multiple-reaction type including the two-site nonlinear equilibrium-kinetic models and the concurrent- and consecutive-multireaction models were modified to describe commonly observed time-dependent behaviors of heavy metals in soils. We also show that equilibrium Langmuir and kinetic second-order models can be extended to simulate the competitive sorption and transport in soils, although the use of such models is limited due to their simplifying assumptions. A major drawback of the empirically based Freundlich and Langmuir approaches is that their associated parameters are specific for each soil. Alternatively, geochemical models that are based on ion-exchange and surface-complexation concepts are capable of quantifying the competitive behavior of several chemical species under a wide range of environmental conditions. Such geochemical models, however, are incapable of describing the time-dependent sorption behavior of heavy metal ions in competitive systems. Further research is needed to develop a general-purpose model based on physical and chemical mechanisms governing competitive sorption in soils. Copyright

  15. Sorption of actinides in granitic rock

    International Nuclear Information System (INIS)

    Allard, B

    1982-11-01

    The sorption of americium (III), neptunium(V) and plutonium on geologic media under oxic conditions has been measured by a batch technique. The aqueous phase was a synthetic groundwater or 4M NaCl solution. The solid phase was a pure mineral, representative of igneous rocks, or granite. Altogether 40 different minerals and rocks were used. The effects of pH and the ionic strength of the aqueous phase as well as of the cation exchange capacity and the surface/mass ratio of the solid sorbent are discussed. Empirical equations giving the distribution coefficient as a function of pH in the environmental pH-range 7-9 are suggested. Some observations and conclusions concerning sorption mechanisms are given. (author)

  16. Sorption of zinc on human teeth

    International Nuclear Information System (INIS)

    Helal, A.; Amin, H.; Alian, G.

    1997-01-01

    Zinc containing dental amalgams are sometimes used as fillings by dentists. The freshly mixed mass of the amalgam alloy and liquid mercury packed or condensed into a prepared tooth cavity. Zinc has been included in amalgams alloys up to 2% as an aid in manufacturing by helping to produce clean sound castings of the ingots. Although such restorations have a relatively long service life, they are subject to corrosion and galvanic action, thus releasing metallic products into the oral environment. The aim of this paper is to investigate the uptake (sorption) of Zinc ionic species on human teeth using the radioactive tracer technique. For this purpose the isotope Zn-65 produced from pile-irradiation of zinc metal was used. The various liquids studied were drinking water (tap water), tea, coffee, red tea and chicken soup. Sorption was studied through immersion of a single human tooth (extracted) in each of these liquids

  17. Sorption of 60 Co on inorganic solids

    International Nuclear Information System (INIS)

    Granados C, F.; Bulbulian G, S.; Mardel V, B.

    2003-01-01

    The behavior of sorption of the 60 Co in aqueous solution under static conditions to different values of pH of the aqueous solution (1, 3, 5, 7, and 10) on MgO, MnO 2 , SnO, TiO 2 , activated carbon and calcinate hydrotalcite was investigated. It was found that the best sorbents of the 60 Co was the MnO 2 , activated carbon and TiO 2 whose sorption was incremented when increasing the pH value of the aqueous solutions, in the one case of the hydrated oxides, the 60 Co interacted with the electrically charged surface of the sorbents that depends on the pH of the solution and of the point of zero charge (zpc) of the sorbent. (Author)

  18. Noble metal extraction and sorption concentrating

    International Nuclear Information System (INIS)

    Petrukhin, O.M.; Malofeeva, G.I.

    1985-01-01

    Works performed in the USSR Academy of Sciences GEOCHI laboratory of extraction methods and devoted to selectivity problems of extraction and sorption methods of platinum metal, cadmium and indium concentrating in analytical chemistry are discussed. On choosing complexino. reagent main attention is paid to the selectivity variation based on different stability of metal complexes. Platinum metals are extracted in the form of ion associates when usinq hard, mainly oxyqen-containing, extractants. Coordination-solvated metal complexes are extracted white usinq extractants containing sulfur, trivalent phosphorus and aromatic nitroqen as donor anions. Selectivity is maximum for sulfur- and nitroren-containinq extractants and sorbents. In case of the group extraction of platinum metals sorption is preferable and in case of selective extraction of individual metals, especially, in case of need of relative concentratinq extraction is preferable

  19. Sorption of phenanthrene on agricultural soils

    DEFF Research Database (Denmark)

    Soares, Antonio; Møldrup, Per; Minh, Luong Nhat

    2013-01-01

    Polyaromatic hydrocarbon (PAH) sorption to soil is a key process deciding the transport and fate of PAH, and potential toxic impacts in the soil and groundwater ecosystems, for example in connection with atmospheric PAH deposition on soils. There are numerous studies on PAH sorption in relatively......, 0.25–1-m depth) by the single-point adsorption method. The organic carbon partition coefficient, KOC (liter per kilogram) for topsoils was found generally to fall between the KOC values estimated by the two most frequently used models for PAH partitioning, the Abdul et al. (Hazardous Waste...... & Hazardous Materials 4(3):211–222, 1987) model and Karickhoff et al. (Water Research 13:241–248, 1979) model. A less-recognized model by Karickhoff (Chemosphere 10:833–846, 1981), yielding a KOC of 14,918 L kg−1, closely corresponded to the average measured KOC value for the topsoils, and this model...

  20. Sorption of radionuclides on London clay

    International Nuclear Information System (INIS)

    Berry, J.A.; Bourke, P.J.; Green, A.; Littleboy, A.K.

    1989-02-01

    Techniques for studying the sorption of radionuclides on London clay have been investigated. This work involved the use of through-diffusion, in-diffusion, high-pressure convection and batch methods to study the sorption of iodide, strontium, caesium and americium. Through-diffusion and high-pressure convection methods were found to be most useful for investigating weakly and moderately sorbing nuclides and give realistic values for sorptivity. The batch technique remains the most practical method of obtaining large quantities of data within a relatively short timescale but gives very high sorptivity values. It is however very useful for intercomparisons of nuclides or geological media. The in-diffusion method requires further refinement for use with strongly sorbing nuclides. Good agreement between through-diffusion and high-pressure convection methods was obtained for the sorptivity of strontium, whilst trends observed for caesium by through-diffusion were confirmed by batch measurements. (author)

  1. Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

    Directory of Open Access Journals (Sweden)

    Lyudmila Nikitina

    2018-01-01

    Full Text Available The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at the temperature of 243 K and the pressure of 0.6 MPa. The hydrogen saturation of nanodiamonds changes the positron lifetime. Increase of sorption cycle numbers effects the positron lifetime, as well as the parameters of the Doppler broadening of annihilation line. The electron-positron annihilation being a sensitive method, it allows detecting the electron density fluctuation of the carbon material after hydrogen saturation.

  2. Sorption studies of radioelements on geological materials

    International Nuclear Information System (INIS)

    Berry, John A.; Yui, Mikazu; Kitamura, Akira

    2007-11-01

    Batch sorption experiments have been carried out to study the sorption of uranium, technetium, curium, neptunium, actinium, protactinium, polonium, americium and plutonium onto bentonite, granodiorite and tuff. Mathematical modelling using the HARPHRQ program and the HATCHES database was carried out to predict the speciation of uranium and technetium in the equilibrated seawater, and neptunium, americium and plutonium in the rock equilibrated water. Review of the literature for thermodynamic data for curium, actinium, protactinium and polonium was carried out. Where sufficient data were available, predictions of the speciation and solubility were made. This report is a summary report of the experimental work conducted by AEA Technology during April 1991-March 1998, and the main results have been presented at Material Research Society Symposium Proceedings and published as proceedings of them. (author)

  3. Effect of the modification of a natural mexican zeolite in the sorption of cadmium and 4-chloro phenol

    International Nuclear Information System (INIS)

    Cortes M, R.

    2007-01-01

    Clinoptilolite type zeolite is a material of relative abundance in Mexico, which possess ion exchange properties and it can be used in the removal of metal ions from polluted waters. The external surface of zeolites can be modified with cationic surfactants. This modification could have a negative effect on the removal of metal ions and provides to the material the capacity to adsorb phenolic compounds. For this reason, it is important to know the capability of the modified material on the sorption of metal ions and phenolic compounds, simultaneously. The aim of this work was to evaluate the effect of the external surface modification with surfactant of a Mexican zeolite over its sorption capacity of cadmium and 4-chloro phenol, in batch and column systems. To accomplish that, a clinoptilolite type zeolitic rock from a deposit located in the state of Sonora, Mexico, was used. It was ground, sieved and characterized with different techniques; and its external surface area was modified with hexadecyltrimethylammonium bromide (HDTMA-Br). A grain size fraction was selected to carry out sorption kinetics and equilibrium experiments, as well as packed column tests with zeolitic material and solutions of cadmium and 4-chloro phenol. There are different models proposed in literature that are used to describe sorption kinetics and equilibrium. In this work, the sorption experimental results were adjusted to some of these models to identify controlling mechanisms on the kinetics and equilibrium of the studied systems. The results showed that the cadmium adsorption on natural and modified zeolite was similar in batch systems. For the case of 4-chloro phenol sorption, it was observed that natural zeolite does not retain this compound, while in modified zeolite the sorption is better than other comparable materials. The results also showed that for the case of cadmium sorption, the mechanism involved was ion exchange; while for sorption of 4-chloro phenol, a partition mechanism

  4. Sorption behaviour of herbicides in soils

    International Nuclear Information System (INIS)

    Luchini, L.C.; Wiendl, F.M.; Ruegg, E.F.; Instituto Biologico, Sao Paulo

    1988-01-01

    Environmental contamination by herbicides is related with the sorption phenomenon of these compounds in the soils. The behaviour of paraquat, 2,4-D and diuron was studied in soils with different physico-chemical properties, through the Freundlich adsorption and desorption isotherms, using 14 C-radiolabeled herbicides. Results of the range of the adsorption-desorption of each herbicide was related mainly with the chemical characteristics of these compounds. (author) [pt

  5. Phosphate sorption characteristics of European alpine soils

    Czech Academy of Sciences Publication Activity Database

    Kaňa, Jiří; Kopáček, Jiří; Camarero, L.; Garcia-Pausas, J.

    2011-01-01

    Roč. 75, č. 3 (2011), s. 862-870 ISSN 0361-5995 R&D Projects: GA ČR(CZ) GA526/09/0567; GA AV ČR(CZ) KJB600960907 Grant - others:EU EMERGE(CZ) EVK1-CT-1999-00032 Institutional research plan: CEZ:AV0Z60170517 Keywords : phosphate sorption * alpine soil s * acidification Subject RIV: DJ - Water Pollution ; Quality Impact factor: 1.979, year: 2011

  6. Moisture sorption isotherms of dehydrated whey proteins

    Directory of Open Access Journals (Sweden)

    Suzana Rimac Brnčić

    2010-03-01

    Full Text Available Moisture sorption isotherms describe the relation between the moisture content of the dry material (food and relative humidity of the surrounding environment. The data obtained are important in modelling of drying process conditions, packaging and shelf-life stability of food that will provide maximum retaining of aroma, colour and texture as well as nutritive and biological value. The objective of this research was to establish the equilibrium moisture content and water activity, as well as monolayer value of two commercial powdered whey protein isolates before and after tribomechanical micronisation and enzymatic hydrolysis, respectively. At the same time it was necessary to evaluate the best moisture sorption isotherm equation to fit the experimental data. The equilibrium moisture contents in investigated samples were determined using standard gravimetric method at 20 °C. The range of water activities was 0.11 to 0.75. The monolayer moisture content was estimated from sorption data using Brunauer-Emmett-Teller (BET and Guggenheim-Anderson-de Boer (GAB models. The results have shown that tribomechanically treated whey protein isolates as well as protein hydrolizates had lower monolayer moisture content values as well as higher corresponding water activity. Therefore, in spite of the fact that they have lower moisture content, they can be storage at higher relative humidity compared to untreated samples. BET model gave better fit to experimental sorption data for a water activity range from 0.11-0.54, while GAB model gave the closest fit for a water activity to 0.75.

  7. Moisture sorption isotherms of dehydrated whey proteins

    OpenAIRE

    Suzana Rimac Brnčić; Vesna Lelas; Zoran Herceg; Marija Badanjak

    2010-01-01

    Moisture sorption isotherms describe the relation between the moisture content of the dry material (food) and relative humidity of the surrounding environment. The data obtained are important in modelling of drying process conditions, packaging and shelf-life stability of food that will provide maximum retaining of aroma, colour and texture as well as nutritive and biological value. The objective of this research was to establish the equilibrium moisture content and water activity, as well as...

  8. Sorption studies of caesium by complex hexacyanoferrates

    International Nuclear Information System (INIS)

    Jacobi, D.

    1992-01-01

    A comprehensive literature review was carried out on the preparation of complex hexacyanoferrates in a granular form suitable for use in a packed column. The preparation of sodium nickel hexacyanoferrate using a freeze-thaw method was studied in detail and a method developed to produce a consistent and reproducible granular product. The equilibrium and sorption kinetics were studied using batch and column tests, and the process modelled to predict performance under various conditions. (author)

  9. A kinetic approach to model sorption dynamics of radionuclides in soils: from desire to operational application?

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Garin, A.; Garcia-Sanchez, L.; Coppin, F. [Institut de Radioprotection et de Surete Nucleaire (France); Krimissa, M. [Electricite de France (France)

    2014-07-01

    The understanding of radionuclides (RN) behaviour and subsequent fluxes in the soil/solution/plant system is still a challenging question for realistic short, medium or long term risk assessments. Several years of researches have been devoted to improve the modeling of radionuclides migration in soils and their transfer to other compartments of the biosphere (eg. plants), as well as to constitute databases of model parameters (eg. distribution coefficient (K{sub d})). These works contributed to define, and then to extend, the domain of applicability of radioecological models, but they also helped to identify gaps and ways to improve them. However, these improvements have not been fully taken into account. Within this framework, the evolution of RN chemical speciation in time (often described as aging) was specifically addressed, as it control RN retention properties and bioavailability. Regarding soluble and RN solid speciation in soils, such processes generally lead to a shift from low to high K{sub d} values. Common explanations consist in the transfer of sorbed RN to non-(or less) exchangeable solid species, or in the lixiviation of the most available radionuclide fraction, both decreasing the reversibly sorbed RN fraction. Kinetics studies have examined such changes in K{sub d} value with time and various models have been proposed to fit the different evolutions. Among them, an empirical three-box model is often used to describe the kinetics of RN sorption when RN mostly occurs in the soil solution as a free ion (eg. Cs and Sr). This model assumes that the radionuclide may be sorbed either as a labile fraction, defining an exchangeable K{sub d}-like liquid/solid distribution, or sorbed as a less or non-exchangeable fraction. The last is estimated through its corresponding sorption and desorption rate constants, which describes a pseudo-first order reaction. Modeling of sorption dynamic is a way to link K{sub d} values derived from field-contaminated soils to

  10. Sorption of antimony on human teeth

    International Nuclear Information System (INIS)

    Nofal, M.; Amin, H.; Alian, G.

    1997-01-01

    The study of the uptake of toxic elements on human teeth represents an interesting research area, as the fate of these elements when present in the human food is of health significance. Since antimony is one of the common toxic elements and since, the chemical behaviour of antimony is similar to that of arsenic, one of the most important toxic elements commonly encountered in cases of food poisoning, it has been decided to investigate its uptake on human teeth and on other restoration materials. The radioactive tracer technique was used to evaluate the concentration of antimony sorbed on teeth. This tracer was obtained by irradiation of antimony metal in the reactor, subsequent dissolution in concentrated sulphuric acid, evaporation to dryness and making the solution 6 M in Hydrochloric acid (1). Antimony prepared in this way is in the trivalent state (Sb III). Sorption was studied in water, tea, coffee, red tea and chicken soup. The highest sorption was achieved from water and chicken soup and least sorption was noticed in case of coffee. The results are presented in the form of the depletion of the radioactivity (A) of antimony with time in presence of a tooth in water and other drinks

  11. Sorption of radon-222 to natural sediments

    International Nuclear Information System (INIS)

    Wong, C.S.; Chin, Y.P.; Gschwend, P.M.

    1992-01-01

    The sorption of radon to sediments was investigated, since this may affect the use of porewater radon profiles for estimating bed irrigation rates. Batch experiments showed that radon has an organic-carbon-normalized sediment-water partition coefficient (K oc , L kg oc -1 ) of 21.1 ± 2.9 for a Boston Harbor sediment, 25.3 ± 2.1 for a Charles River sediment, and 22.4 ± 2.6 for a Buzzards Bay sediment. These values are in close agreement with predictions using radon's octanol-water partition coefficient (K ow ), which was measured to be 32.4 ± 1.5. Temperature and ionic strength effects on K oc were estimated to be small. Given rapid sorption kinetics, the authors suggest that slurry stripping techniques used by many investigators to measure 222 Rn in sediment samples collect both sorbed and dissolved radon. Sorption effects were included in a transport model to obtain revised estimates of irrigation rates from existing literature profiles. Irrigation rates had to be increased over previously reported values in proportion to the sediment organic matter content

  12. Radionuclide sorption studies on abyssal red clays

    International Nuclear Information System (INIS)

    Erickson, K.L.

    1979-01-01

    The radionuclide sorption properties of a widely distributed abyssal red clay are being experimentally investigated using batch equilibration techniques. This paper summarizes sorption equilibrium data obtained when 0.68 N NaCl solutions containing either Tc, U, Pu, Am or Cm were contacted with samples of the red clay and also summarizes some initial results from experiments designed to determine the relative selectivity of the clay for various nuclides. Under mildly oxidizing conditions, the sorption equilibrium distribution coefficients for technetium were essentially zero. At solution-phase nuclide concentrations on the order of 10 -6 M and less and at solution pH values of about 6.9, the distribution coefficients for plutonium were about 3 x 10 3 m1/gm and for uranium, americium, and curium were about 10 5 ml/gm or greater. However, at solution pH values of about 2.7, the distribution coefficients for each of the nuclides were greatly diminished. Initial experiments conducted in order to determine the relative selectivity of the clay for cesium, barium, and cerium, indicated that the silicate phases in the clay were selective for cesium over barium and cerium. These experiments also indicated that the hydrous oxide phases were selective for cerium over barium and for barium over cesium

  13. Lead sorption-desorption from organic residues.

    Science.gov (United States)

    Duarte Zaragoza, Victor M; Carrillo, Rogelio; Gutierrez Castorena, Carmen M

    2011-01-01

    Sorption and desorption are mechanisms involved in the reduction of metal mobility and bioavailability in organic materials. Metal release from substrates is controlled by desorption. The capacity of coffee husk and pulp residues, vermicompost and cow manure to adsorb Pb2+ was evaluated. The mechanisms involved in the sorption process were also studied. Organic materials retained high concentrations of lead (up to 36,000 mg L(-1)); however, the mechanisms of sorption varied according to the characteristics of each material: degree of decomposition, pH, cation exchange capacity and percentage of organic matter. Vermicompost and manure removed 98% of the Pb from solution. Lead precipitated in manure and vermicompost, forming lead oxide (PbO) and lead ferrite (PbFe4O7). Adsorption isotherms did not fit to the typical Freundlich and Langmuir equations. Not only specific and non-specific adsorption was observed, but also precipitation and coprecipitation. Lead desorption from vermicompost and cow manure was less than 2%. For remediation of Pb-polluted sites, the application of vermicompost and manure is recommended in places with alkaline soils because Pb precipitation can be induced, whereas coffee pulp residue is recommended for acidic soils where Pb is adsorbed.

  14. Sorption of heavy metals by the soil fungi 'Aspergillus niger' and Mucor rouxii

    Energy Technology Data Exchange (ETDEWEB)

    Mullen, M.D.; Wolf, D.C.; Beveridge, T.J.; Bailey, G.W.

    1992-01-01

    Sorption of the nitrate salts of cadmium(II), copper(II), lanthanum(III) and silver(I) by two fungi, Aspergillus niger and Mucor rouxii, was evaluated using Freundlich adsorption isotherms and energy dispersive X-ray electron microscopy. The linearized Freundlich isotherm described the metal sorption data well for metal concentrations of 5 microM-1 mM metal. Differences in metal binding were observed among metals, as well as between fungal species. Calculated Freundlich K values indicated that metal binding decreased in the order La(3+) > or = Ag(+) > Cu(2+) > Cd(2+). However, sorption of Ag(+) was greater than that of La(3+) from solutions of 0.1 and 1 mM metal and likely due to precipitation at the cell wall surface. At the 1 mM initial concentration, there were no significant differences between the two fungi in metal sorption, except for Ag(+) binding. At the 5 microM concentration, there was no difference between the fungi in their sorption capacities for the four metals. Electron microscopy-energy dispersive X-ray analysis indicated that silver precipitated onto cells as colloidal silver. The results indicate that Freundlich isotherms may be useful for describing short-term metal sorption by fungal biomass and for comparison with other soil constituents in standardized systems. (Copyright (c) 1992 Pergamon Press plc.)

  15. Arsenic sorption to nanoparticulate mackinawite (FeS): An examination of phosphate competition.

    Science.gov (United States)

    Niazi, Nabeel Khan; Burton, Edward D

    2016-11-01

    Nanoparticulate mackinawite (FeS) can be an important host-phase for arsenic (As) in sulfidic, subsurface environments. Although not previously investigated, phosphate (PO 4 3- ) may compete with As for available sorption sites on FeS, thereby enhancing As mobility in FeS-bearing soils, sediments and groundwater systems. In this study, we examine the effect of PO 4 3- on sorption of arsenate (As(V)) and arsenite (As(III)) to nanoparticulate FeS at pH 6, 7 and 9. Results show that PO 4 3- (at 0.01-1.0 mM P) did not significantly affect sorption of either As(V) or As(III) to nanoparticulate FeS at initial aqueous As concentrations ranging from 0.01 to 1.0 mM. At pH 9 and 7, sorption of both As(III) and As(V) to nanoparticulate FeS was similar, with distribution coefficient (K d ) values spanning 0.76-15 L g -1 (which corresponds to removal of 87-98% of initial aqueous As(III) and As(V) concentrations). Conversely, at pH 6, the sorption of As(III) was characterized by substantially higher K d values (6.3-93.4 L g -1 ) than those for As(V) (K d  = 0.21-0.96 L g -1 ). Arsenic K-edge X-ray absorption near edge structure (XANES) spectroscopy indicated that up to 52% of the added As(V) was reduced to As(III) in As(V) sorption experiments, as well as the formation of minor amounts of an As 2 S 3 -like species. In As(III) sorption experiments, XANES spectroscopy also demonstrated the formation of an As 2 S 3 -like species and the partial oxidation of As(III) to As(V) (despite the strictly O 2 -free experimental conditions). Overall, the XANES data indicate that As sorption to nanoparticulate FeS involves several redox transformations and various sorbed species, which display a complex dependency on pH and As loading but that are not influenced by the co-occurrence of PO 4 3- . This study shows that nanoparticulate FeS can help to immobilize As(III) and As(V) in sulfidic subsurface environments where As co-exists with PO 4 3- . Copyright © 2016 Elsevier Ltd. All

  16. Quantification of Cation Sorption to Engineered Barrier Materials Under Extreme Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Powell, Brian [Clemson Univ., SC (United States); Schlautman, Mark [Clemson Univ., SC (United States); Rao, Linfeng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Nitsche, Heino [Univ. of California, Berkeley, CA (United States); Gregorich, Kenneth [Univ. of California, Berkeley, CA (United States)

    2016-02-02

    The objective of this research is to examine mechanisms and thermodynamics of actinide sorption to engineered barrier materials (iron (oxyhydr)oxides and bentonite clay) for nuclear waste repositories under high temperature and high ionic strength conditions using a suite of macroscopic and microscopic techniques which will be coupled with interfacial reaction models. Gaining a mechanistic understanding of interfacial processes governing the sorption/sequestration of actinides at mineral-water interfaces is fundamental for the accurate prediction of actinide behavior in waste repositories. Although macroscale sorption data and various spectroscopic techniques have provided valuable information regarding speciation of actinides at solid-water interfaces, significant knowledge gaps still exist with respect to sorption mechanisms and the ability to quantify sorption, particularly at high temperatures and ionic strengths. This objective is addressed through three major tasks: (1) influence of oxidation state on actinide sorption to iron oxides and clay minerals at elevated temperatures and ionic strengths; (2) calorimetric titrations of actinide-mineral suspensions; (3) evaluation of bentonite performance under repository conditions. The results of the work will include a qualitative conceptual model and a quantitative thermodynamic speciation model describing actinide partitioning to minerals and sediments, which is based upon a mechanistic understanding of specific sorption processes as determined from both micro-scale and macroscale experimental techniques. The speciation model will be a thermodynamic aqueous and surface complexation model of actinide interactions with mineral surfaces that is self-consistent with macroscopic batch sorption data, calorimetric and potentiometric titrations, X-ray absorption Spectroscopy (XAS, mainly Extended X-ray Absorption Fine Structure (EXAFS)), and electron microscopy analyses. The novelty of the proposed work lies largely in

  17. Quantification of Cation Sorption to Engineered Barrier Materials Under Extreme Conditions

    International Nuclear Information System (INIS)

    Powell, Brian; Schlautman, Mark; Rao, Linfeng; Nitsche, Heino; Gregorich, Kenneth

    2016-01-01

    The objective of this research is to examine mechanisms and thermodynamics of actinide sorption to engineered barrier materials (iron (oxyhydr)oxides and bentonite clay) for nuclear waste repositories under high temperature and high ionic strength conditions using a suite of macroscopic and microscopic techniques which will be coupled with interfacial reaction models. Gaining a mechanistic understanding of interfacial processes governing the sorption/sequestration of actinides at mineral-water interfaces is fundamental for the accurate prediction of actinide behavior in waste repositories. Although macroscale sorption data and various spectroscopic techniques have provided valuable information regarding speciation of actinides at solid-water interfaces, significant knowledge gaps still exist with respect to sorption mechanisms and the ability to quantify sorption, particularly at high temperatures and ionic strengths. This objective is addressed through three major tasks: (1) influence of oxidation state on actinide sorption to iron oxides and clay minerals at elevated temperatures and ionic strengths; (2) calorimetric titrations of actinide-mineral suspensions; (3) evaluation of bentonite performance under repository conditions. The results of the work will include a qualitative conceptual model and a quantitative thermodynamic speciation model describing actinide partitioning to minerals and sediments, which is based upon a mechanistic understanding of specific sorption processes as determined from both micro-scale and macroscale experimental techniques. The speciation model will be a thermodynamic aqueous and surface complexation model of actinide interactions with mineral surfaces that is self-consistent with macroscopic batch sorption data, calorimetric and potentiometric titrations, X-ray absorption Spectroscopy (XAS, mainly Extended X-ray Absorption Fine Structure (EXAFS)), and electron microscopy analyses. The novelty of the proposed work lies largely in

  18. Mathematical Modeling of Moisture Sorption Isotherms and Determination of Isosteric Heats of Sorption of Ziziphus Leaves

    Directory of Open Access Journals (Sweden)

    Amel Saad

    2014-01-01

    Full Text Available Desorption and adsorption equilibrium moisture isotherms of Ziziphus spina-christi leaves were determined using the gravimetric-static method at 30, 40, and 50°C for water activity (aw ranging from 0.057 to 0.898. At a given aw, the results show that the moisture content decreases with increasing temperature. A hysteresis effect was observed. The experimental data of sorption were fitted by eight models (GAB, BET, Henderson-Thompson, modified-Chung Pfost, Halsey, Oswin, Peleg, and Adam and Shove. After evaluating the models according to several criteria, the Peleg and Oswin models were found to be the most suitable for describing the sorption curves. The net isosteric heats of desorption and adsorption of Ziziphus spina-christi leaves were calculated by applying the Clausius-Clapeyron equation to the sorption isotherms and an expression for predicting these thermodynamic properties was given.

  19. Removal and co-transport of Zn, As(V), and Cd during leachate seepage through downgradient mine soils: A batch sorption and column study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Juhee [Division of Environmental Science and Ecological Engineering, Korea University, Seoul (Korea, Republic of); Nam, Seung Mo [Korea Testing and Research Institute, Gyeonggi-do (Korea, Republic of); Hyun, Seunghun, E-mail: soilhyun@korea.ac.kr [Division of Environmental Science and Ecological Engineering, Korea University, Seoul (Korea, Republic of)

    2016-05-01

    The removal of Zn, As(V), and Cd during the leachate seepage process was measured in single, binary, and ternary solute systems by batch sorption and 1-D column flow experiments, followed by a sequential extraction procedure (SEP). In single-solute systems, sorption (K{sub d}{sup ⁎}) occurred in the order of As(V) > Zn ≫ Cd, and this sequence did not change in the presence of other solutes. In multi-solute systems, the sorption of Zn (~ 20%) and Cd (~ 27%) was enhanced by As(V), while Zn and Cd suppressed the sorption of each other. In all cases, As(V) sorption was not affected by the cations, indicating that As(V) is prioritized by sorption sites to a much greater degree than Zn and Cd. Element retention by column soils was strongly correlated (r{sup 2} = 0.77) with K{sub d}{sup ⁎}. Across column segments, mass retention was in the order of inlet (36–54%) > middle (26–35%) > outlet (20–31%), except for Cd in the Zn–Cd binary system. The result of SEP revealed that most of the retained Cd (98–99%) and Zn (56–71%) was in the labile fraction (e.g., the sum of F1 and F2) while only 9–12% of As(V) was labile and most (> 55%) was specifically adsorbed to Fe/Al oxides. Plots of the labile fraction (f{sub labile}) and the fast sorption fraction (f{sub fast}) suggested that the kinetics of specific As(V) sorption occur rapidly (f{sub fast} > f{sub labile}), whereas labile Zn and Cd sorption occurs slowly (f{sub labile} > f{sub fast}), indicating the occurrence of kinetically limited labile sorption sites, probably due to Zn–Cd competition. In conclusion, the element leaching potential of mine leachate can be greatly attenuated during downgradient soil seepage. However, when assessing the soil attenuation process, the impact of sorption competitors and the lability of adsorbed elements should first be considered. - Highlights: • During soil seepage, element leaching potential is reduced as As(V) > Zn > Cd. • Element removal during leachate seepage

  20. Geochemical modelling of the sorption of tetravalent radioelements

    International Nuclear Information System (INIS)

    Bond, K.A.; Tweed, C.J.

    1991-05-01

    The results of an experimental study of the sorption of a range of tetravalent radioelements, plutonium (IV), tin (IV), thorium(IV) and uranium(IV), onto clay at pH8 and pH11 have been successfully simulated using a triple layer sorption model. The model has been incorporated into HARPHRQ, a geochemical program based on PHREEQE. The model has been parameterised using data for sorption onto ferric oxyhydroxide and goethite. The effects of hydroxycarboxylic acids on the sorption process have also been investigated experimentally. It was generally observed that in the presence of 2x10 -3 M gluconate, sorption was reduced by up two orders of magnitude. The model has satisfactorily simulated these lower sorptivities, through assuming competing sorption and complexation reactions. This work, therefore, further confirms the need to take account of such organic materials in safety assessment modelling. (author)

  1. Investigation of metal ions sorption of brown peat moss powder

    Science.gov (United States)

    Kelus, Nadezhda; Blokhina, Elena; Novikov, Dmitry; Novikova, Yaroslavna; Chuchalin, Vladimir

    2017-11-01

    For regularities research of sorptive extraction of heavy metal ions by cellulose and its derivates from aquatic solution of electrolytes it is necessary to find possible mechanism of sorption process and to choice a model describing this process. The present article investigates the regularities of aliovalent metals sorption on brown peat moss powder. The results show that sorption isotherm of Al3+ ions is described by Freundlich isotherm and sorption isotherms of Na+ i Ni2+ are described by Langmuir isotherm. To identify the mechanisms of brown peat moss powder sorption the IR-spectra of the initial brown peat moss powder samples and brown peat moss powder samples after Ni (II) sorption were studied. Metal ion binding mechanisms by brown peat moss powder points to ion exchange, physical adsorption, and complex formation with hydroxyl and carboxyl groups.

  2. Characterization of a low frequency magnetic noise from a two stage pulse tube cryocooler

    International Nuclear Information System (INIS)

    Eshraghi, Mohamad Javad; Sasada, Ichiro; Kim, Jin Mok; Lee, Yong Ho

    2008-01-01

    Magnetic noise of a two stage pulse tube cryocooler(PT) has been measured by a fundamental mode orthogonal fluxgate magnetometer and by a LTS SQUID gradiometer. The magnetometer was installed in a Dewar made of aluminum at 12 cm apart from a section containing magnetic regenerative materials of the PT. The magnetic noise shows a clear peak at 1.8 Hz which is the fundamental frequency of the He gas pumping rate. The 1.8 Hz magnetic noise took a peak, during the cooling process, when the cold stage temperature was at (or close to) 12 K, which resembles the variation of the temperature of the second cold stage of 1.8 Hz. Hence we attributed the main source of this magnetic noise to the temperature dependency of magnetic susceptibility of magnetic regenerative materials such as Er3Ni and HoCu2 used at the second stage. We pointed out that the superconducting magnetic shield by lead sheets reduced the interfering magnetic noise generated from this part. With this scheme, the magnetic noise amplitude measured with the first order gradiometer DROS, mounted in the vicinity of the magnetic regenerator, when the noise amplitude is minimum, which could be found from the fluxgate measurement results, was less than 500 pT peak to peak. Whereas without lead shielding the noise level was higher than the dynamic range of SQUID instrumentations which is around ±10nT. (author)

  3. Operating characteristics of a three-stage Stirling pulse tube cryocooler operating around 5 K

    Science.gov (United States)

    Qiu, L. M.; Cao, Q.; Zhi, X. Q.; Han, L.; Gan, Z. H.; Yu, Y. B.; Liu, Y.; Zhang, X. J.; Pfotenhauer, J. M.

    2012-07-01

    A Stirling pulse tube cryocooler (SPTC) operating at the liquid-helium temperatures represents an excellent prospect for satisfying the requirements of space applications because of its compactness, high efficiency and reliability. However, the working mechanism of a 4 K SPTC is more complicated than that of the Gifford McMahon (GM) PTC that operates at the relatively low frequency of 1-2 Hz, and has not yet been well understood. In this study, the primary operating parameters, including frequency, charge pressure, input power and precooling temperature, are systematically investigated in a home-developed separate three-stage SPTC. The investigation demonstrates that the frequency and precooling temperature are closely coupled via phase shift. In order to improve the cooling capacity it is important to lower the frequency and the precooling temperature simultaneously. In contrast to the behavior predicted by previous studies, the pressure dependence of the gas properties results in an optimized pressure that decreases significantly as the temperature is lowered. The third stage reaches a lowest temperature of 4.97 K at 29.9 Hz and 0.91 MPa. A cooling power of 25 mW is measured at 6.0 K. The precooling temperature is 23.7 K and the input power is 100 W.

  4. MODELLING AND FAILURE ANALYSIS OF FLEXURE SPRINGS FOR A STIRLING CRYOCOOLER

    Directory of Open Access Journals (Sweden)

    RAJESH V. R.

    2017-04-01

    Full Text Available In the range of milliwatt to a few watts cooling capacity, Stirling cycle and pulse tube coolers are most suitable for producing cryogenic temperatures owing to their eco-friendliness, high efficiency, cooling capacity to mass ratio etc. The compressor of a Stirling cooler is powered by a linear motor. The power piston of the cooler is held in position and moves to and fro with the support of so called flexure springs or flexure bearings. Flexures avoid direct contact between moving parts of the compressor of the cooler. Thus, if designed adequately to withstand fatigue, flexure bearings can easily outlast rolling element bearings and slider bearings. In this work, a computational analysis is used to study the performance of flexure spring by varying the geometrical parameters. Three of the most common spring materials namely, SS304, beryllium copper and spring steel are considered for analysis. The analysis was made by varying the parameters like spiral sweep angle, slot width, number of spirals and disc thickness. The influence of each of these parameters on the fatigue life of the spring has been investigated. The results suggest that flexure springs of three spiral arms would be the ideal choice for the selected cryocooler. The variation of stress developed with respect to different design parameters and fatigue damage factor are presented graphically.

  5. Development of a linear compressor for compact 2 K Gifford- McMahon cryocoolers

    International Nuclear Information System (INIS)

    Hiratsuka, Y

    2015-01-01

    Recently, a new, compact Gifford-McMahon (GM) cryocooler for cooling superconducting single photon detectors (SSPD) has been developed at Sumitomo Heavy Industries, Ltd. (SHI) [1, 2]. The objective is to reduce the total height of the expander by 33% relative to the existing RDK-101 GM expander and to reduce the total volume of the compressor unit by 50% relative to the existing CNA-11 compressor. In addition, considering the targeted cooling application, we set the design temperature targets of the first and the second stages to 1 W and 20 mW of heat load at 60 K and 2.3 K, respectively. Although optimization of the internal components is one way to miniaturize the volume of the compressor unit, major design changes are required because the volume of the adsorber and the oil separator is almost the same as the volume of the compressor capsule. Thus, one approach is to develop a non-lubricated compressor, such as a valved linear compressor. An experimental unit of a valved linear compressor was designed and built, and preliminary experiments were conducted. Under no-load condition, a low temperature of 2.19 K has been achieved. With 1 W and 14 mW heat load, the temperature is 48 K at the first stage and 2.3 K at the second stage, with an input power of about 1.2 KW. The detailed experimental results will be discussed in this paper. (paper)

  6. Study on the flow nonuniformity in a high capacity Stirling pulse tube cryocooler

    Science.gov (United States)

    You, X.; Zhi, X.; Duan, C.; Jiang, X.; Qiu, L.; Li, J.

    2017-12-01

    High capacity Stirling-type pulse tube cryocoolers (SPTC) have promising applications in high temperature superconductive motor and gas liquefaction. However, with the increase of cooling capacity, its performance deviates from well-accepted one-dimensional model simulation, such as Sage and Regen, mainly due to the strong field nonuniformity. In this study, several flow straighteners placed at both ends of the pulse tube are investigated to improve the flow distribution. A two-dimensional model of the pulse tube based on the computational fluid dynamics (CFD) method has been built to study the flow distribution of the pulse tube with different flow straighteners including copper screens, copper slots, taper transition and taper stainless slot. A SPTC set-up which has more than one hundred Watts cooling power at 80 K has been built and tested. The flow straighteners mentioned above have been applied and tested. The results show that with the best flow straightener the cooling performance of the SPTC can be significantly improved. Both CFD simulation and experiment show that the straighteners have impacts on the flow distribution and the performance of the high capacity SPTC.

  7. Sorption of citalopram, irbesartan and fexofenadine in soils: Estimation of sorption coefficients from soil properties.

    Science.gov (United States)

    Klement, Aleš; Kodešová, Radka; Bauerová, Martina; Golovko, Oksana; Kočárek, Martin; Fér, Miroslav; Koba, Olga; Nikodem, Antonín; Grabic, Roman

    2018-03-01

    The sorption of 3 pharmaceuticals, which may exist in 4 different forms depending on the solution pH (irbesartan in cationic, neutral and anionic, fexofenadine in cationic, zwitter-ionic and anionic, and citalopram cationic and neutral), in seven different soils was studied. The measured sorption isotherms were described by Freundlich equations, and the sorption coefficients, K F (for the fixed n exponent for each compound), were related to the soil properties to derive relationships for estimating the sorption coefficients from the soil properties (i.e., pedotransfer rules). The largest sorption was obtained for citalopram (average K F value for n = 1 was 1838 cm 3  g -1 ) followed by fexofenadine (K F  = 35.1 cm 3/n μg 1-1/n g -1 , n = 1.19) and irbesartan (K F  = 3.96 cm 3/n μg 1-1/n g -1 , n = 1.10). The behavior of citalopram (CIT) in soils was different than the behaviors of irbesartan (IRB) and fexofenadine (FEX). Different trends were documented according to the correlation coefficients between the K F values for different compounds (R IRB,FEX  = 0.895, p-valuesoil properties in the pedotransfer functions. While the K F value for citalopram was positively related to base cation saturation (BCS) or sorption complex saturation (SCS) and negatively correlated to the organic carbon content (Cox), the K F values of irbesartan and fexofenadine were negatively related to BCS, SCS or the clay content and positively related to Cox. The best estimates were obtained by combining BCS and Cox for citalopram (R 2  = 93.4), SCS and Cox for irbesartan (R 2  = 96.3), and clay content and Cox for fexofenadine (R 2  = 82.9). Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Incorporating IGCC and CaO sorption-enhanced process for power generation with CO2 capture

    International Nuclear Information System (INIS)

    Chen, Shiyi; Xiang, Wenguo; Wang, Dong; Xue, Zhipeng

    2012-01-01

    Highlights: ► CaO sorption-enhanced process is incorporated with IGCC for CO 2 capture. ► IGCC–CCS is simplified using CaO sorption-enhanced process. ► The electricity efficiency is around 31–33% and CO 2 capture efficiency exceeds 95%. ► Parameters such as sorption pressure influence the system performance. -- Abstract: Integrated gasification combined cycle (IGCC) is a power generation technology to convert solid fuels into electricity. IGCC with CCS is regarded as a promising option to mitigate CO 2 emission. In this paper, the CaO sorption-enhanced process is incorporated downstream with coal gasification to produce a hydrogen-rich stream for electricity production and CO 2 separation. A WGS-absorber substitutes the high- and low-temperature water–gas shift reactors and desulfurization units in conventional IGCC–CCS to produce a hydrogen-rich stream, which is sent onto a gas turbine. CaO is used as the sorbent to enhance hydrogen production and for CO 2 capture. Regeneration of CaO is completed via calcination in a regenerator vessel. The IGCC with CaO sorption-enhanced process is modeled and simulated using Aspen Plus software. Two commercial available gasification technologies, Shell and Texaco, are integrated with the sorption-enhanced process. The results showed IGCC with CaO sorption-enhanced process has a satisfactory system performance. Even though the net electricity efficiency is not as high as expected, just around 30–33%, the system has a high CO 2 capture efficiency ∼97% and low pollutant emissions. Moreover, compared with conventional IGCC–CCS, the schematic diagram of the IGCC–CCS process is simplified. Parameters that affect the plant performance are analyzed in the sensitive analysis, including WGS-absorber temperature, H 2 O/CO ratio, pressure, etc. Some challenges to the system are also discussed.

  9. Sorption databases for increasing confidence in performance assessment - 16053

    International Nuclear Information System (INIS)

    Richter, Anke; Brendler, Vinzenz; Nebelung, Cordula; Payne, Timothy E.; Brasser, Thomas

    2009-01-01

    requires that all mineral constituents of the solid phase are characterized. Another issue is the large number of required parameters combined with time-consuming iterations. Addressing both approaches, we present two sorption databases, developed mainly by or under participation of the Forschungszentrum Dresden-Rossendorf (FZD). Both databases are implemented as relational databases, assist identification of critical data gaps and the evaluation of existing parameter sets, provide web based data search and analyses and permit the comparison of SCM predictions with K d values. RES 3 T (Rossendorf Expert System for Surface and Sorption Thermodynamics) is a digitized thermodynamic sorption database (see www.fzd.de/db/RES3T.login) and free of charge. It is mineral-specific and can therefore also be used for additive models of more complex solid phases. ISDA (Integrated Sorption Database System) connects SCM with the K d concept but focuses on conventional K d . The integrated datasets are accessible through a unified user interface. An application case, K d values in Performance Assessment, is given. (authors)

  10. suitability of murram for phosphorus sorption in constructed wetlands

    African Journals Online (AJOL)

    Mimi

    sorption isotherms, determination of Phosphorus sorption capacity of the substrates, determination of. Phosphorus sorption as the function of time and determination of effect of temperature on the ... (Na2O + K2O) % SiO2. %. P2O5. %. TiO2. %. LOI. %. 19.2. 1.3. 0.69. 5.13. 0.05. 6.7. 61.9. 0.04. 0.51. 4.4. As presented in ...

  11. Mechanism of cesium sorption on potassium titanium hexacyanoferrate

    International Nuclear Information System (INIS)

    Sun Yongxia; Xu Shiping; Song Chongli

    1998-01-01

    The mechanism of cesium sorption on potassium titanium hexacyanoferrate is described. The dependence of the sorption speed on temperature, particle granule size, and the stirring speed is studied. The results show that the sorption process is controlled by liquid film diffusion and particle diffusion. An exchange reaction occurs mainly between K + in the exchanger and Cs + in the solution, i.e. potassium titanium hexacyanoferrate, and Cs + of simulated high-level liquid waste

  12. 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

  13. Gravimetric and volumetric approaches adapted for hydrogen sorption measurements with in situ conditioning on small sorbent samples

    International Nuclear Information System (INIS)

    Poirier, E.; Chahine, R.; Tessier, A.; Bose, T.K.

    2005-01-01

    We present high sensitivity (0 to 1 bar, 295 K) gravimetric and volumetric hydrogen sorption measurement systems adapted for in situ sample conditioning at high temperature and high vacuum. These systems are designed especially for experiments on sorbents available in small masses (mg) and requiring thorough degassing prior to sorption measurements. Uncertainty analysis from instrumental specifications and hydrogen absorption measurements on palladium are presented. The gravimetric and volumetric systems yield cross-checkable results within about 0.05 wt % on samples weighing from (3 to 25) mg. Hydrogen storage capacities of single-walled carbon nanotubes measured at 1 bar and 295 K with both systems are presented

  14. Sorption of curium by silica colloids: Effect of humic acid

    International Nuclear Information System (INIS)

    Kar, Aishwarya Soumitra; Kumar, Sumit; Tomar, B.S.; Manchanda, V.K.

    2011-01-01

    Sorption of curium by silica colloids has been studied as a function of pH and ionic strength using 244 Cm as a tracer. The sorption was found to increase with increasing pH and reach a saturation value of ∼95% at pH beyond 5.3. The effect of humic acid on the sorption of 244 Cm onto silica was studied by changing the order of addition of the metal ion and humic acid. In general, in the presence of humic acid (2 mg/L), the sorption increased at lower pH (<5) while it decreased in the pH range 6.5-8 and above pH 8, the sorption was found to increase again. As curium forms strong complex with humic acid, its presence results in the enhancement of curium sorption at lower pH. At higher pH the humic acid present in the solution competes with the surface sites for curium thus decreasing the sorption. The decrease in the Cm sorption in presence of humic acid was found to be less when humic acid was added after the addition of curium. Linear additive model qualitatively reproduced the profile of the Cm(III) sorption by silica in presence of humic acid at least in the lower pH region, however it failed to yield quantitative agreement with the experimental results. The results of the present study evidenced the incorporation of Cm into the silica matrix.

  15. Determining Sorption Rate by a Continuous Gravimetric Method

    National Research Council Canada - National Science Library

    Hall, Monicia R; Procell, Lawrence R; Bartram, Philip W; Shuely, Wendel J

    2003-01-01

    ... were automatically recorded in an Excel file while CARC coupons were submerged in solvent. Initial sorption rates were determined for butyl acetate, butyl ether, cyclohexane and propylene carbonate...

  16. The sorption of polonium, actinium and protactinium onto geological materials

    International Nuclear Information System (INIS)

    Baston, G.M.N.; Berry, J.A.; Brownsword, M.; Heath, T.G.; Ilett, D.J.; McCrohon, R.; Tweed, C.J.; Yui, M.

    1999-01-01

    This paper describes a combined experimental and modeling program of generic sorption studies to increase confidence in the performance assessment for a potential high-level radioactive waste repository in Japan. The sorption of polonium, actinium and protactinium onto geological materials has been investigated. Sorption of these radioelements onto bentonite, tuff and granodiorite from equilibrated de-ionized water was studied under reducing conditions at room temperature. In addition, the sorption of actinium and protactinium was investigated at 60 C. Thermodynamic chemical modeling was carried out to aid interpretation of the results

  17. The sorption of polonium, actinium and protactinium onto geological materials

    Energy Technology Data Exchange (ETDEWEB)

    Baston, G.M.N.; Berry, J.A.; Brownsword, M.; Heath, T.G.; Ilett, D.J.; McCrohon, R.; Tweed, C.J.; Yui, M.

    1999-07-01

    This paper describes a combined experimental and modeling program of generic sorption studies to increase confidence in the performance assessment for a potential high-level radioactive waste repository in Japan. The sorption of polonium, actinium and protactinium onto geological materials has been investigated. Sorption of these radioelements onto bentonite, tuff and granodiorite from equilibrated de-ionized water was studied under reducing conditions at room temperature. In addition, the sorption of actinium and protactinium was investigated at 60 C. Thermodynamic chemical modeling was carried out to aid interpretation of the results.

  18. Comparison of neptunium sorption results using batch and column techniques

    International Nuclear Information System (INIS)

    Triay, I.R.; Furlano, A.C.; Weaver, S.C.; Chipera, S.J.; Bish, D.L.

    1996-08-01

    We used crushed-rock columns to study the sorption retardation of neptunium by zeolitic, devitrified, and vitric tuffs typical of those at the site of the potential high-level nuclear waste repository at Yucca Mountain, Nevada. We used two sodium bicarbonate waters (groundwater from Well J-13 at the site and water prepared to simulate groundwater from Well UE-25p No. 1) under oxidizing conditions. It was found that values of the sorption distribution coefficient, Kd, obtained from these column experiments under flowing conditions, regardless of the water or the water velocity used, agreed well with those obtained earlier from batch sorption experiments under static conditions. The batch sorption distribution coefficient can be used to predict the arrival time for neptunium eluted through the columns. On the other hand, the elution curves showed dispersivity, which implies that neptunium sorption in these tuffs may be nonlinear, irreversible, or noninstantaneous. As a result, use of a batch sorption distribution coefficient to calculate neptunium transport through Yucca Mountain tuffs would yield conservative values for neptunium release from the site. We also noted that neptunium (present as the anionic neptunyl carbonate complex) never eluted prior to tritiated water, which implies that charge exclusion does not appear to exclude neptunium from the tuff pores. The column experiments corroborated the trends observed in batch sorption experiments: neptunium sorption onto devitrified and vitric tuffs is minimal and sorption onto zeolitic tuffs decreases as the amount of sodium and bicarbonate/carbonate in the water increases

  19. Experimental study of strontium sorption on fissure filling material

    Energy Technology Data Exchange (ETDEWEB)

    Eriksen, T E; Cui, Daqing [Royal Institute of Technology, Stockholm (Sweden). Dept. of Chemistry

    1994-12-01

    We have carried out a comparative study of sorption and desorption of strontium in groundwater on separated magnetic and size fractions of fissure filling material taken from natural fissures in granitic rock. Complete reversibility of the sorption process was demonstrated by identical Freundlich isotherms, isotopic exchangeability and pH dependence of the distribution coefficients Rd. The sorption was found to be strongly pH dependent in the range 3-11. The pH effect can be accommodated in the sorption model by considering the surface areas and surface charges of the minerals in the fissure fil