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Sample records for cation exchange capacity

  1. Determining the cation exchange capacity of montmorillonite by simultaneous thermal analysis method

    Science.gov (United States)

    Boeva, N. M.; Bocharnikova, Yu. I.; Belousov, P. E.; Zhigarev, V. V.

    2016-08-01

    A way of determining the cation exchange capacity of montmorillonite by simultaneous thermal analysis is developed using as an example the bentonites of the 10th Khutor deposit (Republic of Khakassia) and the Vodopadnyi area (Sakhalin Island). A correlation is established between the cation exchange capacity of smectite and its weight loss upon heating in the range of dehydration; the enthalpy of dehydration of montmorillonite; and the weight loss and the enthalpy of thermal dissociation of ethylene glycol contained in the interlayer space of the mineral's crystal structure. These data open up new possibilities for determining the cation exchange capacity of montmorillonite, the most important technological indicator of the natural clay nanomineral.

  2. Effect of Lanthanum Accumulation on Cation Exchange Capacity and Solution Composition of Red Soil

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Pot and adsorption-exchange experiments were carried out by collecting the soil samples from the surface layer (0~15 cm) of red soil at the Ecological Experiment Station of Red Soil, the Chinese Academy of Sciences, in Jiangxi Province of China. When concentration of the exogenous La3+ exceeded 400 mg kg-1, there was less non-exchangeable La3+ than exchangeable La3+ in the soil. Cation exchange capacity of the soil changed slightly with increasing concentration of the exogenous La3+ in both experiments. However, in the adsorption-exchange experiment, when concentration of the exogenous La3+ was higher than 300 mg kg-1, exchangeable basic cations decreased significantly, while exchangeable hydrogen and exchangeable aluminum increased significantly compared with the control treatments. The amounts of base cations (Ca2+, Mg2+, K+ and Na+) exchanged by La3+ in the supernatant solution increased with the concentration of the exogenous La3+, especially when concentration of the exogenous La3+ was higher than 50 mg kg-1.

  3. Radial variations in cation exchange capacity and base saturation rate in the wood of pedunculate oak and European beech

    Energy Technology Data Exchange (ETDEWEB)

    Herbauts, J.; Penninckx, V.; Gruber, W.; Meerts, P. [Universite Libre de Bruxelles, Laboratoire de genetique et d' ecologie vegetales, Brussels (Belgium)

    2002-10-01

    Visual observation of pedunculate oak trees and European beech trees in a mixed forest stand in the Belgian Ardennes revealed decreasing cation concentration profiles in wood. In order to determine whether these profiles are attributable to endogenous factors or to decreased availability of cations in the soil, radial profiles of water-soluble, exchangeable and total cations were investigated. Cation exchange capacity of wood was also determined. Results showed wood cation exchange capacity to decrease from pith to bark in European beech and from pith to outer heartwood in pedunculate oak. Decreasing profiles of exchangeable calcium and magnesium in peduncular oak and exchangeable calcium in European beech were found to be strongly constrained by cation exchange capacity, and thus not related to environmental change. Base cation saturation rate showed no consistent radial change in either species. It was concluded that the results did not provide convincing evidence to attribute the decrease in divalent cation concentration in pedunculate oak and European beech in this location to be due to atmospheric pollution. 42 refs., 1 tab., 4 figs.

  4. CATION EXCHANGE CAPACITY OF DOMINANT SOIL TYPES IN THE REPUBLIC OF CROATIA

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    Marija Tomasic

    2013-09-01

    Full Text Available The study was conducted on 18 locations and 11 dominant soil types in the Republic of Croatia including their evolution-genetic horizons. In total, 51 soil samples were examined. Analysis of soil was done by saturating patterns using barium chloride solution in three replications. Descriptive statistics of the analyzed data was conducted. Basic statistical parameters were calculated, and functional dependence between the base saturation (V% of analyzed soil samples and their pH was observed. The correlation coefficient (r between base saturation (V% and pH for all examined soils was r=0.79 (n=51; very strong correlation. For acid soils it was r=0.82 (n=17; very strong correlation, for neutral soils r=0.75 (n=8; very strong correlation, and finally for alkaline soils r=0.15 (n=26; very weak correlation. Cation exchange capacity values ranged from 2.39 cmol+*kg-1 to 33.8 cmol+*kg-1 depending on soil type, pH, organic content and other soil parameters. The content of exchangeable cations in the sum of basic cations ranged from: Ca2+ (16% - 94%, Mg2+ (2% - 41%, K+ (1% - 68% and Na+ (<0.01% also depending on soil type, depth, location and other physical and chemical soil parameters.

  5. A simple method for estimating cation exchange capacity from water vapor sorption

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus

    2016-01-01

    Knowledge of soil cation exchange capacity (CEC) is crucial for soil fertility considerations, sorption and release of polar and non-polar compounds, engineering applications, and other biogeochemical processes. Standard procedures such as the ammonium acetate or the BaCl2 compulsive exchange...... methods are expensive and laborious, and in previous studies the CEC has been predicted from parameters such as particle size distribution and organic matter content, specific surface area, clay content, and from Atterberg limits. In this study, relative humidity (RH)-dependent pedotransfer functions...... (PTFs) for estimating CEC from soil water content considering hysteresis have been developed based on 203 differently-textured soils. Furthermore, we compared the performance of the new PTFs with existing PTFs that predict CEC from clay content, organic carbon, soil pH and specific surface area. The new...

  6. The Cation Exchange Capacity of Fibrous Feedstuff and Its Nutritive Characteristics

    Institute of Scientific and Technical Information of China (English)

    XING Ting-xian

    2003-01-01

    Current researches on the nutritive characteristics of fibrous feedstuff through determining thefeedstuff cation exchange capacity (CEC) to evaluate its nutritive value at home and abroad were comprehen-sively discribed, and the methods of determining CEC value and the correlation between CEC value and chemi-cal compositions, pH value, and the effect of CEC value on the digestion kinetics in ruminants were also em-phatically introduced. The results of research showed that the CEC values of different feedstuff are different,closely correlated with nitrogen and acid detergent fibre (ADF) and lignin (LIG) content of the feedstuff. Atthe same time, there are markedly effect of CEC value in diet on the nutrients flow of digesta in the digestivetract of ruminants, the degradation rate and digestibility of nutrients in the rumen.

  7. Synthesis of high capacity cation exchangers from a low-grade Chinese natural zeolite.

    Science.gov (United States)

    Wang, Yifei; Lin, Feng

    2009-07-30

    The Chinese natural zeolite, in which clinoptilolite coexists with quartz was treated hydrothermally with NaOH solutions, either with or without fusion with NaOH powder as pretreatment. Zeolite Na-P, Na-Y and analcime were identified as the reacted products, depending on the reaction conditions such as NaOH concentration, reaction time and hydrothermal temperature. The products were identified by X-ray diffraction, and characterized by Fourier transform IR and ICP. With hydrothermal treatment after fusion of natural zeolite with NaOH, high purity of zeolite Na-Y and Na-P can be selectively formed, their cation exchange capacity (CEC) are 275 and 355 meq/100g respectively, which are greatly higher than that of the natural zeolite (97 meq/100g). Furthermore, the ammonium removal by the synthetic zeolite Na-P in aqueous solution was also studied. The equilibrium isotherms have been got and the influence of other cations present in water upon the ammonia uptake suggested an order of preference Ca(2+)>K(+)>Mg(2+).

  8. Synthesis of high capacity cation exchangers from a low-grade Chinese natural zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yifei, E-mail: yifeiwang0206@yahoo.com.cn [College of Biology and Chemical Engineering, Jiaxing University, Jiaxing, Zhejiang 314001 (China); Department of Chemistry, XiXi Campus, Zhejiang University, Hangzhou, Zhejiang 310028 (China); Lin Feng [Department of Chemistry, XiXi Campus, Zhejiang University, Hangzhou, Zhejiang 310028 (China)

    2009-07-30

    The Chinese natural zeolite, in which clinoptilolite coexists with quartz was treated hydrothermally with NaOH solutions, either with or without fusion with NaOH powder as pretreatment. Zeolite Na-P, Na-Y and analcime were identified as the reacted products, depending on the reaction conditions such as NaOH concentration, reaction time and hydrothermal temperature. The products were identified by X-ray diffraction, and characterized by Fourier transform IR and ICP. With hydrothermal treatment after fusion of natural zeolite with NaOH, high purity of zeolite Na-Y and Na-P can be selectively formed, their cation exchange capacity (CEC) are 275 and 355 meq/100 g respectively, which are greatly higher than that of the natural zeolite (97 meq/100 g). Furthermore, the ammonium removal by the synthetic zeolite Na-P in aqueous solution was also studied. The equilibrium isotherms have been got and the influence of other cations present in water upon the ammonia uptake suggested an order of preference Ca{sup 2+} > K{sup +} > Mg{sup 2+}.

  9. Effects of Acetate on Cation Exchange Capacity of a Zn-Containing Montmorillonite : Physicochemical Significance and Metal Uptake

    NARCIS (Netherlands)

    Stathi, P.; Papadas, I. T.; Enotiadis, A.; Gengler, R. Y. N.; Gournis, D.; Rudolf, P.; Deligiannakis, Y.

    2009-01-01

    Fundamental properties such as cation exchange capacity (CEC), permanent charge, pH(PZC), and metal uptake of a Zn-containing montmorillonite are modified, in a predictable manner, by a mild chemical treatment using acetate. Acetate treatment allows a controllable increase of the CEC of montmorillon

  10. Influence of Sulfonated-Kaolin On Cationic Exchange Capacity Swelling Degree and Morphology of Chitosan/Kaolin Composites

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    Ozi Adi Saputra

    2016-06-01

    Full Text Available Preparation of sulfonated-kaolin (sKao has been conducted and used as filler on chitosan matrix via solution casting method, namely chitosan/sKao (Cs/sKao. Swelling degree, cationic exchange capacity and thermal stability were evaluated to determine chitosan/sKao membranes performance as proton exchange membrane in fuel cell. Functional group analysis of chitosan, sKao and synthesized products were studied using Fourier Transform Infra-Red (FTIR spectroscopy. In this study, swelling degree and swelling area of Cs/sKao are also studied to determine of membrane ability to swelling which compare to unmodified chitosan/kaolin (Cs/Kao. The presence of sKao in chitosan matrix was able to improve cationic exchange capacity (CEC which proved by morphological study of membrane surface after CEC test. Moreover, Thermal stability of Cs/sKao showed the membrane has meet requirement for PEM application.

  11. Spatial Variability of Soil Cation Exchange Capacity in Hilly Tea Plantation Soils Under Different Sampling Scales

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Studies on the spatial variability of the soil cation exchange capacity (CEC) were made to provide a theoretical basis for an ecological tea plantation and management of soil fertilizer in the tea plantation. Geostatistics were used to analyze the spatial variability of soil CEC in the tea plantation site on Mengding Mountain in Sichuan Province of China on two sampling scales. It was found that, (1) on the small scale, the soil CEC was intensively spatially correlative, the rate of nugget to sill was 18.84% and the spatially dependent range was 1 818 m, and structural factors were the main factors that affected the spatial variability of the soil CEC; (2) on the microscale, the soil CEC was also consumingly spatially dependent,and the rate of nugget to sill was 16.52%, the spatially dependent range was 311 m, and the main factors affecting the spatial variability were just the same as mentioned earlier. On the small scale, soil CEC had a stronger anisotropic structure on the slope aspect, and a weaker one on the lateral side. According to the ordinary Kriging method, the equivalence of soil CEC distributed along the lateral aspect of the slope from northeast to outhwest, and the soil CEC reduced as the elevation went down. On the microscale, the anisotropic structure was different from that measured on the small scale. It had a stronger anisotropic structure on the aspect that was near the aspect of the slope, and a weaker one near the lateral aspect of the slope. The soil CEC distributed along the lateral aspect of the slope and some distributed in the form of plots.From the top to the bottom of the slope, the soil CEC increased initially, and then reduced, and finally increased.

  12. Comparison between methods using copper, lanthanum, and colorimetry for the determination of the cation exchange capacity of plant cell walls.

    Science.gov (United States)

    Wehr, J Bernhard; Blamey, F Pax C; Menzies, Neal W

    2010-04-28

    The determination of the cation exchange capacity (CEC) of plant cell walls is important for many physiological studies. We describe the determination of cell wall CEC by cation binding, using either copper (Cu) or lanthanum (La) ions, and by colorimetry. Both cations are strongly bound by cell walls, permitting fast and reproducible determinations of the CEC of small samples. However, the dye binding methods using two cationic dyes, Methylene Blue and Toluidine Blue, overestimated the CEC several-fold. Column and centrifugation methods are proposed for CEC determination by Cu or La binding; both provide similar results. The column method involves packing plant material (2-10 mg dry mass) in a chromatography column (10 mL) and percolating with 20 bed volumes of 1 mM La or Cu solution, followed by washing with deionized water. The centrifugation method uses a suspension of plant material (1-2 mL) that is centrifuged, and the pellet is mixed three times with 10 pellet volumes of 1 mM La or Cu solution followed by centrifugation and final washing with deionized water. In both methods the amount of La or Cu bound to the material was determined by spectroscopic methods.

  13. Suitability of the methylene blue test for determination of cation exchange capacity of clay minerals related to ammonium acetate method

    Science.gov (United States)

    Milošević, Maja; Logar, Mihovil; Dojčinović, Biljana; Erić, Suzana

    2015-04-01

    Cation exchange capacity (CEC) represents one of the most important parameters of clay minerals which reflects their ability to exchange cations with liquid phases in near contact. Measurement of CEC is used for characterizing sample plasticity, adsorbing and swelling properties which later define their usage in industrial purposes. Several methods have been developed over the years for determination of layer charge, charge density, charge distribution, etc. and have been published in numerous papers (Czimerova et al., 2006; Yukselen and Kaya, 2008). The main goal of present study is comparison of suitability of more recent method - methylene blue test in regard to older method - ammonium acetate for determination of CEC. For this study, we selected one montmorillonite clay (Bogovina, Serbia) and two mainly kaolinite clays (Miličinica, Serbia). Chemicals used for CEC determinations were solution of methylene blue (MB)(14*10-6M/ml) and ammonium acetate (AA) solution (1M). The obtained results are showing generally lower values in case of MB method. The main difference is due to molecular aggregation of MB on the clay surface. AA method is highly sensitive to the presence of CaO. Release of Ca ion from the sample into the solution can limit the saturation of exchange sites by the ammonium ion. This is clearly visible in case of montmorillonite clay. Fe2+ and Mg ions are difficult to move by the ammonium ion because of their ion radius, but in case of MB molecule there is no such restriction in removing them from the exchange sites. MB solution, even in a low concentration (2*10-6M/ml), is showing preferable results in moving the ions from their positions which is already visible after adding a small quantity of solution (25cm3). Both MB-titration and MB-spot test yield similar results and are much simpler methods than AA and they also give other information such as specific surface area (external and internal) whereas AA method only provides information about

  14. COMPOSITE OF CHITOSAN VANILIN / SULFONATED POLYSTYRENE AS POLYMER ELECTROLYTE MEMBRANES : CATIONIC EXCHANGE CAPACITY, SWELLING DEGREE AND THERMAL PROPERTIES

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    Edi Pramono

    2016-08-01

    Full Text Available Research on the preparation and characterization of sulfonated polystyrene (PST /chitosan vanillin (KV composite as electrolyte membranes has been conducted in order to investigate the effect of PST and KV composition to its chemical and physical properties. Polystyrene was modified by sulfonation reaction to produces PST, meanwhile chitosan was modified by schift base reaction to produces KV. The composite membranes were prepared by casting method and were characterized in order to identify the functional groups contained in the composite, the cation exchange capacity (CEC, the Swelling Degree (SD, the thermal properties and the morphology. The peak of imine vibration in the FTIR spectrum indicates that the chitosan vanilin was succesfully synthesized. Meanwhile, the peak of sulfonate vibration indicates the product of sulfonation on polystyrene. The result of CEC analysis shows that the addition of sulfonate groups on polystyrene and the addition of phenolic groups on chitosan increase the CEC value. The increasing of PST and KV concentration in membrane enhance the CEC value. However, the increasing of PST concentration in membrane composition even decrease the Swelling Degree of membranes. Meanwhile, the increasing of KV concentration increase the swelling degree of membranes. Thermal analysis shows that the thermal decomposition of membranes occurs in three stages i.e. the dehydration of water molecules, the degradation of the subtituen groups and the plasticizer and the degradation of the back bone of chitosan and polystyrene.

  15. Obtention of the cation exchange capacity of a natural kaolinite with radioactive tracers; Obtencion de la capacidad de intercambio cationico de una kaolinita natural con trazadores radioactivos

    Energy Technology Data Exchange (ETDEWEB)

    Uribe I, A.; Badillo A, V.E. [Universidad Autonoma de Zacatecas, 98000 Zacatecas (Mexico); Monroy G, F. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: Adrya81@hotmail.com

    2005-07-01

    One of the more used techniques for the elimination of the heavy metals present in water systems is to use adsorbent mineral phases like zeolites and clays, among others. The clays are able to exchange easily the fixed ions in the external surface of its crystals or well the ions present in the interlaminar spaces of the structures, for other existent ones in the encircling aqueous solutions for that the Cation exchange capacity (CIC) is defined as the sum of all the cations exchange that a mineral can possess independent to the physicochemical conditions. The CIC is equal to the measure of the total of negative charges of the mineral by mass of the solid (meq/g). In this investigation work, the value of the CIC equal to 2.5 meq/100 g is obtained, of a natural kaolinite from the State of Hidalgo studying the retention of the sodium in the kaolinite with the aid of the radioactive isotope {sup 24} Na and of the selective electrodes technique, making vary the pH value. So is experimentally demonstrated that the CIC is an intrinsic property of the mineral independent of the pH value of the solution and of the charges origin. (Author)

  16. Recommandations pour la détermination expérimentale de la capacité d'échange de cations des milieux argileux Recommendations for Experimentally Determining the Cation-Exchange Capacity of Shaly Media

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    Chambre Syndicale du Pétrole$

    2006-11-01

    Full Text Available Cet article présente une méthode relativement simple et précise destinée à la détermination de la capacité d'échanges de cations des milieux argileux qui permet de caractériser la réactivité des argiles. Cette mesure présente une certaine importance en raison des problèmes posés par les réservoirs argileux (interprétation des diagraphies, efficacité des méthodes de récupération améliorée par voie chimique. . . . Après avoir brièvement rappelé les propriétés fondamentales des argiles, la capacité d'échanges de cations (CEC est définie et la méthode recommandée de mesure de celle-ci (dosage par le chlorure de cobaltihexammine est décrite. Trois exemples viennent ensuite illustrer cette méthode dans le cas d'une argile pure, d'un sable argileux et d'un échantillon de grès argileux consolidé. This article describes a relatively simple and accurate method for determining the cation-exchange capacity of shaly media, which enables the characterization of the clay reactivity. This measurement is of some importance because of the problems posed by shaly reservoirs (interpreting well logs, effectiveness of improved-recovery methods by chemical means, etc. . After a brief review of the fondamental properties of shales, the cation-exchange capacity (CEC is defined, and the recommended measurement method by using cobaltihexammine chloride is described. Three examples are then given to illustrate this method for pure clay, for a shaly Band and for a consolidated shaly sandstone.

  17. Investigations on Cationic Exchange Capacity and Unused Bed Zone according to operational conditions in a Fixed Bed Reactor for water lead removal by a natural zeolite

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    Barthélemy JP.

    2006-01-01

    Full Text Available In this study, attention has been focused on the behaviour of the Cationic Exchange Capacity (CEC and the Unused Bed Zone (UBZ, according to the operating parameters (bed length: L, column diameter: D, particle diameter: d and fl ow rate: Q in a Fixed Bed Reactor (FBR. The investigations are performed for a single-component study of lead on New Zealand clinoptilolite at 25 ± 1°C. The results show a constant operating CEC of 1.00 ± 0.015 meq.g-1 which is independent of the operational parameters listed above. The performance of the operations expressed as UBZ, shows an optimum for the ratio L/D (bed length and column diameter fi xed at 18.1, for Q = 2.9 BV.h-1 (bed volume per hour and particle diameter d = 0.38 mm (the ratio particle diameter on column diameter d/D at 0.057. This maximum performance is reached with the lowest UBZ value of 5.6% of the operating CEC. Overall interpretation drawn from the results according to UBZ shows that decreasing the particles size improves the performance of ion exchange process; as well as decreasing the fl ow rate. Nevertheless, the increase of L/D to a certain extent does not improve ion exchange performances.

  18. Influência da matéria orgânica na capacidade de troca de cations do solo Cation-exchange capacity of the organic fraction of soils

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    F. da Costa Verdade

    1956-01-01

    . The cation-exchange capacity and other data on these soils show that the organic fraction must play an important role in the cation-exchange process. The study of the adsorptive capacity of the organic matter was done by destruction of the organic fraction of the soil by 12% hydrogen peroxide. For heavy textured soils the results show that the organic fraction most resistant to oxidation had a higher cation-exchange capacity than the portion first oxidized. For sandy soils all organic fractions had the same magnitude in the base adsorbing power. It was observed that the organic matter seems to inhibit the base-exchange capacity of the mineral fraction. Plotting the percentage of cation-exchange capacity of the organic fraction against the percentage of organic carbon in the soil, a curve is determined which shows the inhibition phenomenon. The results were rather scattered and the experiments are now being repeated to elucidate these observations. The organic cation-exchange capacity of soils in São Paulo is 30-40% for fine textured soils and 50-60% for sandy soils. Since most of the farming land in São Paulo belongs to the sandy soil group called Bauru, the problem of maintaining or increasing the fertility of these soils is dependent on their organic matter content.

  19. Synthesis of Strong Acid Cation Exchange Resin with High Exchange Capacity%高交换容量强酸型阳离子交换树脂的合成研究

    Institute of Scientific and Technical Information of China (English)

    罗旻; 赵兴

    2014-01-01

    Strong acid cation exchange resin has many important applications in most fields. Exchange capacity is an important parameter which influences the effect of the resin applied, the better performance of the resin due to its higher exchange capacity mostly. In this paper, the method of synthesis of strong acid cation exchange resin with high exchange capacity was discussed. Based on the influence of the pore-forming agent on the physical structure of the polymer, a small amount of the pore-forming agent was added to the monomer to modify the styrene-divinylbenzene copolymer which was then sulfonated to form the resin. The Na-type exchange capacity of 4.82 mmol/g (dried resin) of the gel type resin (the crosslinkage is 7%) with good mechanical strength was obtained while the experimental optimization was adopted.%强酸型阳离子交换树脂在许多领域有着重要用途。交换容量是影响树脂应用效果的重要参数,更高的交换容量往往赋予树脂更好的应用性能。本文探讨了高交换容量强酸型阳离子交换树脂的合成方法,结合致孔剂对聚合物内部物理结构的影响机理,采用在单体中加入少量致孔剂的方法得到改性的苯乙烯-二乙烯苯共聚物,再经磺化制备树脂。通过实验优化,得到了钠型交换容量为4.82 mmol/g(干树脂)的凝胶型树脂(交联度为7%),且机械强度好。

  20. Acceptable levels of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) in soils, depending on their clay and humus content and cation-exchange capacity

    NARCIS (Netherlands)

    Haan, de S.; Rethfeld, H.; Driel, van W.

    1985-01-01

    Three sandy soils differing in humus content and three clay soils differing in clay content were supplied with heavy metals to determine which loading rate of each single metal should be regarded as critical from the viewpoint of crop yield and metal content dependent on soil cation exchange capacit

  1. Cation exchange properties of zeolites in hyper alkaline aqueous media.

    Science.gov (United States)

    Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

    2015-02-03

    Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media.

  2. Variability of Cation-Exchange Capacity (CEC of Fen Peats in Vertical Profiles from Eastern and Central Poland in Relation to Function of Peatlands as Natural Geological Barriers

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    Rydelek Paweł

    2016-12-01

    Full Text Available An analysis of cation-exchange capacity(CEC variability of peats is presented in vertical pro files from eastern and central Po land. CEC values were com pared with ash con tent (Ac, pH and CaCO3 content. Eight peatlands were selected for re search in the fol lowingareas: War saw Plateau (2 objects, Siedlce Plateau (2 objects, Lubartów Plateau (2 objects, Nałęczów Table land (1 object and Dobrohusk Depression (1 object. The peatlands represented a fen peat type of similar botanic compositions of sediments, but they differed in the area, peat thickness and drain age conditions. Characteristic regular i ties in CEC variability were noted in the peatlands and there were three types of CEC variability in vertical pro files. Carbonate peats (types 1 and 2 had the high est pH and definitely the high est values of CEC. In vertical pro files, there was also a zonation, but the regularities similar to non-carbonate peats were not observed. Different distribution of phys i cal and chem i cal parameters were establishedin vertical pro files in partly drained peatlands (with a muck layer on top with non-carbonate peats (type 3 and there were three distinct zones in vertical pro files, with different Ac and CEC. Determination of the vertical CEC variability and other phys i cal and chem i cal parameters in peatlands made it possible to distinguish zones with potentially most beneficial isolation conditions.

  3. Effect of polyamine reagents on exchange capacity in ion exchangers

    Science.gov (United States)

    Petrova, T. I.; Dyachenko, F. V.; Bogatyreva, Yu. V.; Borodastov, A. K.; Ershova, I. S.

    2016-05-01

    Effect of compounds involved in complex reagents is described using Helamin 906H reagent as an example. The working exchange capacity of KU-2-8chs cation exchanger in hydrogen form and Amberlite IRA 900Cl anion exchanger in OH form remained almost unchanged when they were used repeatedly to purify water that contained Helamin 906H reagent; in addition, this capacity was the same upon filtration of water that did not contain this reagent. Leakage of total organic carbon was observed earlier than that of calcium ions upon filtration of the solution through the cation exchanger layer. The test results obtained in industrial conditions indicated that using H-OH filters to purify turbine condensate enables the decrease of the concentration of organic and other impurities therein.

  4. Effects of Land Use Practices on the Organic Carbon Content, Cation Exchange Capacity and Aggregate Stability of Soils in the Catchment Zones

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    Mosayeb Heshmati

    2011-01-01

    Full Text Available Problem statement: Land use practice leads to changes in the physico-chemical properties of soils, such as Soil Organic Carbon (SOC, Cation Exchange Capacity (CEC and Soil Aggregate Stability (SAS that cause soil erosion. Approach: Merek catchment, Iran suffers from land degradation due to poor land use practice. A study was carried out with the objectives: (i to determine soil nutrient status in different agro-ecological zones in Merek catchment; and (ii to evaluate the influence of land use practices on SOC, CEC and SAS. Results: It was found that soil texture was silty and clay, while soil reaction was alkaline (pH was 7.75. The respective amount of carbonates was 32 and 36% in the top-soil and sub-soil respectively, indicating high level of alkalinity in the soils of the study area. The mean SAS of the surface soil layer for agriculture, rangeland and forest was 53, 61 and 64%, respectively with its mean in the topsoil of agriculture is significantly lower (P≤0.05 than the other zones. SOC level in the agriculture, rangeland and forest were 1.35, 1.56, 2.14 % in the topsoil and 1.03, 1.33 and 1.45%, in the subsoil of the respective areas. The results of t-test and ANOVA analyses showed that SOC means are significantly different from each other within soil depth and among agro-ecological zones. The CEC in the agriculture, rangeland and forest areas were 25.8, 24.6 and 35.1 cmolckg-1 for the top-soil and 31.1, 26.8 and 26.9 cmolckg-1 in the sub-soil, respectively. All the above changes are due to the negative effects of agricultural activities. Conclusion: Improper tillage practice (up-down the slope, conversion of the rangeland and forest to rain-fed areas, crop residue burning, over grazing and forest clearance contribute to reduction in SOC and SAS in the Merek catchment, Iran.

  5. Advancements in Anion Exchange Membrane Cations

    Energy Technology Data Exchange (ETDEWEB)

    Sturgeon, Matthew R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Long, Hai [National Renewable Energy Lab. (NREL), Golden, CO (United States); Park, Andrew M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Pivovar, Bryan S. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-10-15

    Anion-exchange membrane fuel cells (AME-FCs) are of increasingly popular interest as they enable the use of non-Pt fuel cell catalysts, the primary cost limitation of proton exchange membrane fuel cells. Benzyltrimethyl ammonium (BTMA) is the standard cation that has historically been utilized as the hydroxide conductor in AEMs. Herein we approach AEMs from two directions. First and foremost we study the stability of several different cations in a hydroxide solution at elevated temperatures. We specifically targeted BTMA and methoxy and nitro substituted BTMA. We've also studied the effects of adding an akyl spacer units between the ammonium cation and the phenyl group. In the second approach we use computational studies to predict stable ammonium cations, which are then synthesized and tested for stability. Our unique method to study cation stability in caustic conditions at elevated temperatures utilizes Teflon Parr reactors suitable for use under various temperatures and cation concentrations. NMR analysis was used to determine remaining cation concentrations at specific time points with GCMS analysis verifying product distribution. We then compare the experimental results with calculated modeling stabilities. Our studies show that the electron donating methoxy groups slightly increase stability (compared to that of BTMA), while the electron withdrawing nitro groups greatly decrease stability in base. These results give insight into possible linking strategies to be employed when tethering a BTMA like ammonium cation to a polymeric backbone; thus synthesizing an anion exchange membrane.

  6. Preparation of sulfonated cation exchangers from petroleum asphaltites

    Energy Technology Data Exchange (ETDEWEB)

    Pokonova, Yu.V.; Pol' kin, G.B.; Proskuryakov, V.A.

    1980-01-01

    It was established that the reaction of petroleum asphaltite sulfonation is determined in the first step by the chemical reaction rate, and in the last --- by diffusion factors. The kinetic constants were found for each reaction step. Sulfonated cation exchangers were obtained having the characteristics: specific volume of the swollen cation exchanger 3.30 mL/g, bulk density of the air-dry product 0.58 g/mL., moisture content 23.4%, swelling in water 41.6%, mechanical strength 80.0%, static exchange capacity with respect to 0.1N NaOH solution 2.76 mg equiv/g, dynamic exchange capacity with respect to 0.0035N CaC1/sub 2/ solution for a specific load of 10 L/L.h 465 mg equiv/L.

  7. Multi-cycle recovery of lactoferrin and lactoperoxidase from crude whey using fimbriated high-capacity magnetic cation exchangers and a novel "rotor-stator" high-gradient magnetic separator.

    Science.gov (United States)

    Brown, Geoffrey N; Müller, Christine; Theodosiou, Eirini; Franzreb, Matthias; Thomas, Owen R T

    2013-06-01

    Cerium (IV) initiated "graft-from" polymerization reactions were employed to convert M-PVA magnetic particles into polyacrylic acid-fimbriated magnetic cation exchange supports displaying ultra-high binding capacity for basic target proteins. The modifications, which were performed at 25 mg and 2.5 g scales, delivered maximum binding capacities (Qmax ) for hen egg white lysozyme in excess of 320 mg g(-1) , combined with sub-micromolar dissociation constants (0.45-0.69 µm) and "tightness of binding" values greater than 49 L g(-1) . Two batches of polyacrylic acid-fimbriated magnetic cation exchangers were combined to form a 5 g pooled batch exhibiting Qmax values for lysozyme, lactoferrin, and lactoperoxidase of 404, 585, and 685 mg g(-1) , respectively. These magnetic cation exchangers were subsequently employed together with a newly designed "rotor-stator" type HGMF rig, in five sequential cycles of recovery of lactoferrin and lactoperoxidase from 2 L batches of a crude sweet bovine whey feedstock. Lactoferrin purification performance was observed to remain relatively constant from one HGMF cycle to the next over the five operating cycles, with yields between 40% and 49% combined with purification and concentration factors of 37- to 46-fold and 1.3- to 1.6-fold, respectively. The far superior multi-cycle HGMF performance seen here compared to that observed in our earlier studies can be directly attributed to the combined use of improved high capacity adsorbents and superior particle resuspension afforded by the new "rotor-stator" HGMS design.

  8. Cation exchange capacity of an oxisol amended with an effluent from domestic sewage treatment Capacidade de troca catiônica de um latossolo tratado com efluente de tratamento de esgoto doméstico

    Directory of Open Access Journals (Sweden)

    Adriel Ferreira da Fonseca

    2005-12-01

    Full Text Available The addition of Na-rich anthropogenic residues to tropical soils has stimulated the scientific community to study the role of sodium in both the soil solution and the exchange complex. In this study, several different methods were used to calculate the concentration of exchangeable and soluble cations and this data was then used to establish correlations between the level of these cations and both the accumulation of various elements and the dry weight of maize grown in a greenhouse under different conditions. In the closed environments of the pots, the most suitable method for calculating the effective cation exchange capacity (ECEC was the cation exchange capacity calculated by cations removed with barium chloride solution (CEC S. Then again, the actual cation exchange capacity (CEC A should be measured by using Mg adsorption to prevent ionic force from influencing electric charges. A strong positive correlation was obtained between the concentrations of Na in the 1:2 soil:water extracts and the accumulation of Na in the maize plants, indicating saline or double acid extractors are not needed when monitoring the Na concentration only.A disposição de resíduos antropogênicos ricos em sódio nos solos tropicais tem despertado o interesse da comunidade científica em estudar a participação deste elemento no complexo de troca, bem como na solução no solo. Objetivou-se neste trabalho estabelecer correlações entre as concentrações de cátions trocáveis e de cátions solúveis, obtidos por diferentes métodos, com o acúmulo de elementos e com a massa seca no milho. O experimento foi conduzido em casa de vegetação, sob diferentes condições. Para experimentos em ambiente fechado (vasos, o método mais indicado para o cálculo da capacidade de troca catiônica efetiva (CTCe é a capacidade de troca catiônica calculada a partir dos cátions removidos com solução de cloreto de bário. Ainda, a capacidade de troca catiônica atual deve

  9. Production of sulfonated cation-exchangers from petroleum asphaltites

    Energy Technology Data Exchange (ETDEWEB)

    Pokonova, Yu.V.; Pol' kin, G.B.; Proskuryakov, V.A.; Vinogradov, M.V.

    1982-02-10

    Continuing our studies of the preparation of products of practical value from asphaltite, a new by-product of oil refining, we obtained sulfonated cation-exchangers from a mixture of asphaltite and acid tar. It is shown that these cation-exchangers have good kinetic properties and are superior in thermal and thermohydrolytic stability to the commercial cation-exchange resin KU-2.

  10. Determination of effective capacities of ion-exchangeable materials by measuring the equilibrium conductivity.

    Science.gov (United States)

    Okabe, Toshiaki; Yokoyama, Yukio

    2010-01-01

    The effective ion-exchange capacities of ion-exchange materials were determined by measuring the change in the equilibrium conductivity of a column packed with analyte. The developed instrumental method can provide effective ion-exchange capacities for both cation and anion exchangers with simple operations. The cation-exchange capacity of a weak-acid cation-exchange resin (TSKgel SuperIC-Cation column) depended on the conditioning pH and the molar concentration of the conditioning agent. Plots of effective cation-exchange capacities over the conditioning pH exhibited three inflection points, suggesting the presence of two carboxy groups and one phenolic OH group in the resin, probably due to the inherent base polymer. This method was applied to several commercial analytical columns for ion chromatography, and could provide scientifically useful results for characterizing the resin properties.

  11. Review on cation exchange selectivity coefficients for MX-80 bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Domenech, C.; Arcos, D.; Duro, L. [ENVIROS, Passeig de Rubi, 29-31, 08197 Valldoreix (Spain); Sellin, P. [SKB, Brahegatan 47, SE-102 40 Stockholm (Sweden)

    2005-07-01

    Full text of publication follows: Bentonite is considered as engineered barrier in the near field of a nuclear waste repository due to its low permeability, what impedes groundwater flow to the nuclear waste, and its high retention capacity (sorption) of radionuclides in the eventuality of groundwater intrusion. One of the main retention processes occurring at the bentonite surface is ion exchange. This process may exert a strong control on the mobility of major pore water cations. Changes in major cation concentration, especially calcium, can affect the dissolution-precipitation of calcite, which in turn controls one of the key parameters in the system: pH. The cation exchange process is usually described according to the Gaines-Thomas convention: Ca{sup 2+} + 2 NaX = CaX{sub 2} + 2 Na{sup +}, K{sub Ca} = (N{sub Ca} x a{sup 2}{sub Na{sup +}})/(N{sup 2}{sub Na} x a{sub Ca{sup 2+}}) where K{sub Ca} is the selectivity coefficient for the Ca by Na exchange, ai is the activity of cation 'i' in solution and NJ the equivalent fractional occupancy of cation 'J' in bentonite. Parameters such as solid to liquid (S:L) ratio and dry density of the solid have an important influence on the value of selectivity coefficients (K{sub ex}). Although in most geochemical modelling works, K{sub ex} values are directly taken from experiments conducted at low S:L ratios and low dry densities, the expected conditions in a deep geological nuclear waste repository are higher S:L and higher bentonite density (1.6 g.cm{sup -3} in the SKB design to obtain a fully water saturated density of around 2.0 g.cm{sup -3}). Experiments focused at obtaining selectivity coefficients under the conditions of interest face the difficulty of achieving a proper extraction and analyses of pore water without disturbing the system by the sampling method itself. In this work we have conducted a complete analyses of published data on MX-80 bentonite cationic exchange in order to assess the

  12. Sulfonation Process and Desalination Effect of Polystyrene/PVDF Semi-Interpenetrating Polymer Network Cation Exchange Membrane

    Directory of Open Access Journals (Sweden)

    Yin-lin Lei

    2014-07-01

    Full Text Available With the classical sulfonation method of polystyrene-based strongly acidic cation exchange resins, polystyrene/polyvinylidene fluoride (PVDF alloy particles were sulfonated to obtain a cation exchange resin, which was then directly thermoformed to prepare a semi-interpenetrating polymer network (semi-IPN cation exchange membrane. The effects of the swelling agent, sulfonation time and temperature and the relative contents of polystyrene and divinylbenzene (DVB in the alloy particles on the feasibility of the membrane formation are discussed. The results indicate that a favorable sulfonation degree above 80% and a suitable ion exchange capacity of 1.5–2.4 mmol/g can be gained, with concentrated sulfuric acid as the sulfonation agent and 1,2-dichloroethane as the swelling agent. The running electrical resistance and desalination effect of the prepared cation exchange membrane were measured in a pilot-scale electrodialyser and not only obviously exceeded a commercial heterogeneous cation exchange membrane, but was also very close to a commercial homogenous membrane. In this way, the authors have combined the classical sulfonation method of polystyrene-based cation exchange resins with the traditional thermoforming manufacturing process of heterogeneous cation exchange membranes, to successfully develop a novel, low-price, but relatively high-performance polystyrene/PVDF cation exchange membrane with the semi-IPN structure.

  13. Cu Vacancies Boost Cation Exchange Reactions in Copper Selenide Nanocrystals.

    Science.gov (United States)

    Lesnyak, Vladimir; Brescia, Rosaria; Messina, Gabriele C; Manna, Liberato

    2015-07-29

    We have investigated cation exchange reactions in copper selenide nanocrystals using two different divalent ions as guest cations (Zn(2+) and Cd(2+)) and comparing the reactivity of close to stoichiometric (that is, Cu2Se) nanocrystals with that of nonstoichiometric (Cu(2-x)Se) nanocrystals, to gain insights into the mechanism of cation exchange at the nanoscale. We have found that the presence of a large density of copper vacancies significantly accelerated the exchange process at room temperature and corroborated vacancy diffusion as one of the main drivers in these reactions. Partially exchanged samples exhibited Janus-like heterostructures made of immiscible domains sharing epitaxial interfaces. No alloy or core-shell structures were observed. The role of phosphines, like tri-n-octylphosphine, in these reactions, is multifaceted: besides acting as selective solvating ligands for Cu(+) ions exiting the nanoparticles during exchange, they also enable anion diffusion, by extracting an appreciable amount of selenium to the solution phase, which may further promote the exchange process. In reactions run at a higher temperature (150 °C), copper vacancies were quickly eliminated from the nanocrystals and major differences in Cu stoichiometries, as well as in reactivities, between the initial Cu2Se and Cu(2-x)Se samples were rapidly smoothed out. These experiments indicate that cation exchange, under the specific conditions of this work, is more efficient at room temperature than at higher temperature.

  14. Formation of cobalt hydrotalcite by cation exchange of Co2+-substitued zeolite X

    Science.gov (United States)

    Jeong, H. Y.; Lee, K.

    2013-12-01

    Zeolite has been utilized to sequester heavy metals and nuclides due to the high cation exchange capacity. However, once-immobilized cations by zeolite tend to be re-exchanged by other cations (Ca2+, Mg2+, Na+, etc) present in groundwater. Thus, it is important to understand the mechanism associated with re-exchange reactions to predict the environmental fate and behavior of the metal cations sequestered by zeolite. In this study, we performed a series of cation exchange experiments using Co2+-substituted zeolite X (Co-X) in concentrated CaCl2 solutions. The radioactive isotope of cobalt (60Co2+), commonly found in low-to-intermediate level nuclear wastes, undergoes radioactive decay, likely altering the physicochemical properties of zeolite by generating heat and irradiation. To simulate such effects, Co-X was thermally treated at 400 and 600oC before re-exchange experiments. At the higher treatment temperature, the re-exchanged amount of Co2+ in Co-X by Ca2+ was found to decrease. According to X-ray diffraction, the re-exchange led to little change in the zeolite crystallinity for thermally untreated samples, but the significantly decreased crystallinity was noted for re-exchanged, thermally treated samples. Nonetheless, 27Al MAS NMR spectra of all re-exchanged samples revealed that the peaks corresponding to 4-fold coordinated Al became broader with their position shifting as a result of the re-exchange, suggesting that the re-exchange caused a short-range order structural distortion for both thermally untreated and treated samples. Also, Co-K edge X-ray absorption spectroscopy (XAS) was employed to examine the mechanism(s) involved in the re-exchange. By comparison of XAS spectra between re-exchanged samples and model compounds, Co2+ was likely to be either present as an extraframwork cation within zeolite or incorporated into a cobalt hydrotalcite (Co6Al2(OH)16(An-)2/n where An- is an interlayer anion) phase. The relative contribution of an extraframwork Co2

  15. Denatured Thermodynamics of Proteins in Weak Cation-exchange Chromatography

    Institute of Scientific and Technical Information of China (English)

    LI Rong; CHEN Guo-Liang

    2003-01-01

    The thermostability of some proteins in weak cation-exchange chromatography was investigated at 20-80 ℃. The results show that there is a fixed thermal denaturation transition temperature for each protein. The appearance of the thermal transition temperature indicates that the conformations of the proteins are destroyed seriously. The thermal behavior of the proteins in weak cation-exchange and hydrophobic interaction chromatographies were compared in a wide temperature range. It was found that the proteins have a higher thermostability in a weak cation-exchange chromatography system. The thermodynamic parameters(ΔH0, ΔS0) of those proteins were determined by means of Vant Hoff relationship(lnk-1/T). According to standard entropy change(ΔS0), the conformational change of the proteins was judged in the chromatographic process. The linear relationships between ΔH0 and ΔS0 can be used to evaluate "compensation temperature"(β) at the protein denaturation and identify the identity of the protein retention mechanism in weak cation-exchange chromatography.

  16. New cation-exchange membranes for hyperfiltration processes

    NARCIS (Netherlands)

    Velden, van der P.M.; Smolders, C.A.

    1977-01-01

    A new route for the preparation of cation exchange membranes from polystyrene-polyisoprene-polystyrene (SIS) block copolymers has been studied, using N-chlorosulfonyl isocyanate. At temperatures of 0° to 20°C, N-chlorosulfonyl isocyanate reacts readily with the olefin group in polyisoprenes, resulti

  17. Cation immobilization in pyrolyzed simulated spent ion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Luca, Vittorio, E-mail: vluca@cnea.gov.ar [Programa Nacional de Gestion de Residuos Radiactivos, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. General, Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); Bianchi, Hugo L. [Gerencia de Quimica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Av. General, Paz 1499, 1650 San Martin, Provincia de Buenos Aires (Argentina); ECyT, Universidad Nacional de General San Martin, Campus Miguelete, Ed. Tornavias, Martin de Irigoyen 3100, 1650 San Martin (Argentina); Conicet, Av. Rivadavia 1917, 1033 Buenos Aires (Argentina); Manzini, Alberto C. [Programa Nacional de Gestion de Residuos Radiactivos, Comision Nacional de Energia Atomica, Av. Del Libertador 8250, CP 1429, Ciudad Autonoma de Buenos Aires (Argentina)

    2012-05-15

    Significant quantities of spent ion exchange resins that are contaminated by an assortment of radioactive elements are produced by the nuclear industry each year. The baseline technology for the conditioning of these spent resins is encapsulation in ordinary Portland cement which has various shortcomings none the least of which is the relatively low loading of resin in the cement and the poor immobilization of highly mobile elements such as cesium. The present study was conducted with cationic resin samples (Lewatit S100) loaded with Cs{sup +}, Sr{sup 2+}, Co{sup 2+}, Ni{sup 2+} in roughly equimolar proportions at levels at or below 30% of the total cation exchange capacity. Low temperature thermal treatment of the resins was conducted in inert (Ar), or reducing (CH{sub 4}) gas atmospheres, or supercritical ethanol to convert the hydrated polymeric resin beads into carbonaceous materials that contained no water. This pyrolytic treatment resulted in at least a 50% volume reduction to give mechanically robust spherical materials. Scanning electron microscope investigations of cross-sections of the beads combined with energy dispersive analysis showed that initially all elements were uniformly distributed through the resin matrix but that at higher temperatures the distribution of Cs became inhomogeneous. Although Cs was found in the entire cross-section, a significant proportion of the Cs occurred within internal rings while a proportion migrated toward the outer surfaces to form a crustal deposit. Leaching experiments conducted in water at 25 Degree-Sign C showed that the divalent contaminant elements were very difficult to leach from the beads heated in inert atmospheres in the range 200-600 Degree-Sign C. Cumulative fractional loses of the order of 0.001 were observed for these divalent elements for temperatures below 500 Degree-Sign C. Regardless of the processing temperature, the cumulative fractional loss of Cs in water at 25 Degree-Sign C reached a plateau or

  18. Polymethylmethacrylate open tubular ion exchange columns: nondestructive measurement of very small ion exchange capacities.

    Science.gov (United States)

    Zhang, Min; Yang, Bingcheng; Dasgupta, Purnendu K

    2013-08-20

    We describe an approach to prepare an open tubular ion exchange (OTIE) column by coating a monolayer of anion exchange nanoparticle to a 16-20 μm bore polymethylmethacrylate (PMMA) capillary. The latex nanoparticle was electrostatically attached to carboxylate groups on the inner wall of capillary, pretreated with strong base for hydrolyzing the ester. Several approaches to nondestructively measure ion exchange capacities (IEC) of the columns were examined: (a) adsorption-desorption of an intensely fluorescent ion, e.g. fluorescein, and off-line fluorometry, (b) loading a weakly retained ion (e.g., IO3(-)), frontal displacement by a strongly bound ion (e.g., Cl(-)), and online optical or conductometric boundary detection, and (c) similar to the above except displacement being accompanied by reaction (e.g., acid-base titration). To our knowledge, this is the first time on-column titration has been used to measure capacities. By using different pH displacer solutions, we demonstrate for the first time the possibility of pKa-differentiated ion exchange capacity measurements. The cation exchange capacity of bare PMMA capillaries was on the order of 1 pequiv/mm(2) with little dependence on time and temperature of hydrolysis conditions. After AS18 latex coating, the strong base anion exchange capacity was on the order of 10 pequiv/mm(2), very close to what would be estimated on the basis of monolayer coverage of the surface by individual latex particles. The latex used contained a significant, additional amount of weak base character, about the same as the strong base ion exchange capacity.

  19. Properties of sulfonated cation-exchangers made from petroleum asphaltites

    Energy Technology Data Exchange (ETDEWEB)

    Pokonova, Yu.V.; Pol' kin, G.B.; Proskuryakov, V.A.

    1982-01-10

    The use of ion-exchangers in radiochemical technology is accompanied by changes of their properties under the influence of ionizing radiation. The rate of development of these processes depends on the nature and structure of the matrix and on the nature and amount of ionic groups. We have proposed a method of synthesis of ion-exchangers resistant to ..gamma.. radiation from petroleum asphaltites. Continuing these investigations, we prepared cation-exchangers by sulfonation of a mixture of petroleum asphaltites and acid asphalt. An investigation of their radiation resistance is described in this paper.

  20. Selective Facet Reactivity During Cation Exchange in Cadmium Sulfide Nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Sadtler, Bryce; Demchenko, Denis; Zheng, Haimei; Hughes, Steven; Merkle, Maxwell; Dahmen, Ulrich; Wang, Lin-Wang; Alivisatos, A. Paul

    2008-12-18

    The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for cation exchange to take place at different facets of the nanocrystal plays an important role in determining the resulting morphology of the binary heterostructure. In the case of copper I (Cu+) cation exchange in cadmium sulfide (CdS) nanorods, the reaction starts preferentially at the ends of the nanorods such that copper sulfide (Cu2S) grows inwards from either end. The resulting morphology is very different from the striped pattern obtained in our previous studies of silver I (Ag+) exchange in CdS nanorods where non-selective nucleation of silver sulfide (Ag2S) occurs. From interface formation energies calculated for several models of epitaxialconnections between CdS and Cu2S or Ag2S, we infer the relative stability of each interface during the nucleation and growth of Cu2S or Ag2S within the CdS nanorods. The epitaxial connections of Cu2S to the end facets of CdS nanorods minimize the formation energy, making these interfaces stable throughout the exchange reaction. However, as the two end facets of wurtzite CdS nanorods are crystallographically nonequivalent, asymmetric heterostructures can be produced.

  1. Acarbose Isolation with Gel Type Strong Acid Cation Exchange Resin:Equilibrium, Kinetic and Thermodynamic Studies

    Institute of Scientific and Technical Information of China (English)

    王亚军; 于蕾; 郑裕国; 王远山; 沈寅初

    2013-01-01

    Acarbose, a potentα-glucosidase inhibitor, is widely used as an oral anti-diabetic drug for the treatment of the type 2, non-insulin-dependent diabetes. In this work, a gel type strong acid cation exchange resin 001×4 was applied to isolate acarbose from fermentation broth. It was demonstrated that cation exchanger 001×4 displayed a large adsorption capacity and quick exchange rate for acarbose. The static adsorption equilibrium data were well fitted to the Langmuir equation. Column adsorption experiments demonstrated that high dynamic adsorption capacity was reached at bed height of 104.4 mm, feed flow rate of 1.0 ml·min-1 and acarbose concentration of 4.0 mg·ml-1. Under the optimized conditions, the column chromatography packed with cation exchanger 001×4 recovered 74.3%(by mass) of acarbose from Actinoplanes utahensis ZJB-08196 fermentation broth with purity of 80.1%(by mass), demonstrating great potential in the practical applications in acarbose separation.

  2. Sulfonated polyvinyl chloride fibers for cation-exchange microextraction.

    Science.gov (United States)

    Xu, Li; Lee, Hian Kee

    2009-09-18

    Polyvinyl chloride (PVC) fiber was derivatized by concentrated sulfuric acid to yield sulfonated PVC (PVC-SO3H). The PVC-SO3H fiber had dual properties as a sorbent, based on cation-exchange and hydrophobicity. In the present study, the novel fiber was used directly as an individual device for extraction purposes in the cation-exchange microextraction of anaesthetics, followed by high-performance liquid chromatography-UV analysis. The results demonstrated that this PVC-SO3H fiber-based microextraction afforded convenient operation and cost-effective application to basic analytes. The limits of detection for four anaesthetics ranged from 1.2 to 6.0 ng/mL. No carryover (because of its disposable usage), and no loss of sorbent phase (which normally occurs in stir-bar sorptive extraction) during extraction were observed.

  3. Alloyed copper chalcogenide nanoplatelets via partial cation exchange reactions.

    Science.gov (United States)

    Lesnyak, Vladimir; George, Chandramohan; Genovese, Alessandro; Prato, Mirko; Casu, Alberto; Ayyappan, S; Scarpellini, Alice; Manna, Liberato

    2014-08-26

    We report the synthesis of alloyed quaternary and quinary nanocrystals based on copper chalcogenides, namely, copper zinc selenide-sulfide (CZSeS), copper tin selenide-sulfide (CTSeS), and copper zinc tin selenide-sulfide (CZTSeS) nanoplatelets (NPLs) (∼20 nm wide) with tunable chemical composition. Our synthesis scheme consisted of two facile steps: i.e., the preparation of copper selenide-sulfide (Cu2-xSeyS1-y) platelet shaped nanocrystals via the colloidal route, followed by an in situ cation exchange reaction. During the latter step, the cation exchange proceeded through a partial replacement of copper ions by zinc or/and tin cations, yielding homogeneously alloyed nanocrystals with platelet shape. Overall, the chemical composition of the alloyed nanocrystals can easily be controlled by the amount of precursors that contain cations of interest (e.g., Zn, Sn) to be incorporated/alloyed. We have also optimized the reaction conditions that allow a complete preservation of the size, morphology, and crystal structure as that of the starting Cu2-xSeyS1-y NPLs. The alloyed NPLs were characterized by optical spectroscopy (UV-vis-NIR) and cyclic voltammetry (CV), which demonstrated tunability of their light absorption characteristics as well as their electrochemical band gaps.

  4. Impact of sediment-seawater cation exchange on Himalayan chemical weathering fluxes

    Science.gov (United States)

    Lupker, Maarten; France-Lanord, Christian; Lartiges, Bruno

    2016-08-01

    Continental-scale chemical weathering budgets are commonly assessed based on the flux of dissolved elements carried by large rivers to the oceans. However, the interaction between sediments and seawater in estuaries can lead to additional cation exchange fluxes that have been very poorly constrained so far. We constrained the magnitude of cation exchange fluxes from the Ganga-Brahmaputra river system based on cation exchange capacity (CEC) measurements of riverine sediments. CEC values of sediments are variable throughout the river water column as a result of hydrological sorting of minerals with depth that control grain sizes and surface area. The average CEC of the integrated sediment load of the Ganga-Brahmaputra is estimated ca. 6.5 meq 100 g-1. The cationic charge of sediments in the river is dominated by bivalent ions Ca2+ (76 %) and Mg2+ (16 %) followed by monovalent K+ (6 %) and Na+ (2 %), and the relative proportion of these ions is constant among all samples and both rivers. Assuming a total exchange of exchangeable Ca2+ for marine Na+ yields a maximal additional Ca2+ flux of 28 × 109 mol yr-1 of calcium to the ocean, which represents an increase of ca. 6 % of the actual river dissolved Ca2+ flux. In the more likely event that only a fraction of the adsorbed riverine Ca2+ is exchanged, not only for marine Na+ but also Mg2+ and K+, estuarine cation exchange for the Ganga-Brahmaputra is responsible for an additional Ca2+ flux of 23 × 109 mol yr-1, while ca. 27 × 109 mol yr-1 of Na+, 8 × 109 mol yr-1 of Mg2+ and 4 × 109 mol yr-1 of K+ are re-absorbed in the estuaries. This represents an additional riverine Ca2+ flux to the ocean of 5 % compared to the measured dissolved flux. About 15 % of the dissolved Na+ flux, 8 % of the dissolved K+ flux and 4 % of the Mg2+ are reabsorbed by the sediments in the estuaries. The impact of estuarine sediment-seawater cation exchange appears to be limited when evaluated in the context of the long-term carbon cycle and

  5. CATION-EXCHANGE MEMBRANES WITH POLYANILINE SURFACE LAYER FOR WATER TREATMENT

    Directory of Open Access Journals (Sweden)

    Dinar Dilshatovich Fazullin

    2014-01-01

    Full Text Available Ion-exchange membranes are widely used in modern technologies, particularly in the field of water treatment and make it possible to considerably reduce expenses for wastewater treatment and ensure high degree of purification. Currently, perfluorinated sulfated proton-conducting membranes are often used, such as NAFION and its Russian analogue, MF-4SK based on co-polymerization product of a perfluorinated vinyl ether with tetrafluoroethylene. However, with development of the industry, materials with improved properties and lower cost are required. The aim is to obtain ion-exchange membranes for water treatment from metal ions and to study physico-chemical properties of obtained membranes. In this study, cation exchange composite membranes with modified polyaniline surface layer on nylon and PTFE substrate have been obtained. Changes in the structure of membranes were recorded using a microscope. Throughput capacity of the membranes was determined by passing a certain volume of distilled water through the membrane. The experiment intended to determine electivity of membranes was performed by passing a certain volume of metal salt solutions of a known concentration, after which the filtrate was collected. Concentrations of the studied metal ions in the original solution and in the filtrate were determined by the method of atomic adsorptive spectrometry with electro thermal atomization "Quantum Z.ETA". Prepared highly selective ion exchange membranes. Properties of modified membranes, such as selective permeability and ion-exchange capacity have been determined. The membranes feature high selectivity for heavy metal ions. Moisture-retaining power and swelling ability of the membranes have been studied. Selectivity of the membrane to heavy metal ions is between 70 and 99%. Ion-exchange capacity of the obtained nylon polyaniline membrane is not inferior to some commercially available cation-exchange membranes. Use of the modified membranes in the

  6. On the real performance of cation exchange resins in wastewater treatment under conditions of cation competition: the case of heavy metal pollution.

    Science.gov (United States)

    Prelot, Benedicte; Ayed, Imen; Marchandeau, Franck; Zajac, Jerzy

    2014-01-01

    Sorption performance of cation-exchange resins Amberlite® IRN77 and Amberlite™ IRN9652 toward Cs(I) and Sr(II) has been tested in single-component aqueous solutions and simulated waste effluents containing other monovalent (Effluent 1) or divalent (Effluent 2) metal cations, as well as nitrate, borate, or carbonate anions. The individual sorption isotherms of each main component were measured by the solution depletion method. The differential molar enthalpy changes accompanying the ion-exchange between Cs+ or Sr2+ ions and protons at the resin surface from single-component nitrate solutions were measured by isothermal titration calorimetry and they showed a higher specificity of the two resins toward cesium. Compared to the retention limits of both resins under such idealized conditions, an important depression in the maximum adsorption capacity toward each main component was observed in multication systems. The overall effect of ion exchange process appeared to be an unpredictable outcome of the individual sorption capacities of the two resins toward various cations as a function of the cation charge, size, and concentration. The cesium retention capacity of the resins was diminished to about 25% of the "ideal" value in Effluent 1 and 50% in Effluent 2; a further decrease to about 15% was observed upon concomitant strontium addition. The uptake of strontium by the resins was found to be less sensitive to the addition of other metal components: the greatest decrease in the amount adsorbed was 60% of the ideal value in the two effluents for Amberlite® IRN77 and 75% for Amberlite™ IRN9652. It was therefore demonstrated that any performance tests carried out under idealized conditions should be exploited with much caution to predict the real performance of cation exchange resins under conditions of cation competition.

  7. Carbon dioxide and nitrogen adsorption on cation-exchanged SSZ-13 zeolites.

    Science.gov (United States)

    Pham, Trong D; Liu, Qingling; Lobo, Raul F

    2013-01-15

    Samples of high-silica SSZ-13, ion exchanged with protons and alkali-metal cations Li(+), Na(+), and K(+), were investigated using adsorption isotherms of CO(2) and N(2). The results show that Li-, Na-SSZ-13 have excellent CO(2) capacity at ambient temperature and pressure; in general, Li-SSZ-13 shows the highest capacity for N(2), CO(2) particularly in the low-pressure region. The effect of cation type and Si/Al ratio (6 and 12) on the adsorption properties was investigated through analysis of adsorption isotherms and heats of adsorption. The separation of CO(2) in a flue gas mixture was evaluated for these adsorbents in the pressure swing adsorption and vacuum pressure adsorption processes.

  8. Spontaneous Superlattice Formation in Nanorods through PartialCation Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Richard D.; Sadtler, Bryce; Demchenko, Denis O.; Erdonmez, Can K.; Wang, Lin-Wang; Alivisatos, A. Paul

    2007-03-14

    Lattice mismatch strains are widely known to controlnanoscale pattern formation in heteroepitaxy, but such effects have notbeen exploited in colloidal nanocrystal growth. We demonstrate acolloidal route to synthesizing CdS-Ag2S nanorod superlattices throughpartial cation exchange. Strain induces the spontaneous formation ofperiodic structures. Ab initio calculations of the interfacial energy andmodeling of strain energies show that these forces drive theself-organization. The nanorod superlattices exhibit high stabilityagainst ripening and phase mixing. These materials are tunablenear-infrared emitters with potential applications as nanometer-scaleoptoelectronic devices.

  9. Analysis of Adsorption, Ion Exchange, Thermodynamic Behaviour of Some Organic Cations on Dowex 50WX4-50/H+ Cation Exchanger in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Ehteram A. Noor

    2011-01-01

    Full Text Available The equilibrium adsorption, ion exchange characteristics of various concentrations of some organic cations from aqueous solutions onto dowex 50WEX/H+ cation exchanger were studied at different temperatures in the range of 30-50 °C. The studied cations showed good adsorptive properties onto dowex 50WX4-5/H+ at different concentrations and temperatures. Main adsorption behaviour was ion exchange between hydrogen ions and the organic cations as indicated from the linear relation between the initial concentration of the organic cations and the released hydrogen ions. It was found that the adsorption affinity of dowex 50WX4-50/H+ towards the studied organic cations depends on the substituent type of the organic cations giving the following increasing order: 1-H < 2-OH < 3-OCH3. Thermodynamic parameters for the adsorption of the studied organic cations were evaluated and discussed. It was found that the adsorption 1-H organic cation was spontaneous, ordered, exothermic and favored with decreasing temperature. On the other hand the adsorption of both 2-OH and 3-OCH3 organic cations was found to be spontaneous and disordered with enthalpy change varies significantly with increasing organic cation concentration, suggesting dipole-dipole adsorption forces as new active sites for adsorption under conditions of relatively high concentrations. Freundlich and Dubinin-Radushkevich adsorption isotherm models reasonably describe the adsorption of the studied organic cations onto dowex 50WX4-50/H+ by segmented straight lines depending on the studied range of concentration, indicating the existence of two different sets of adsorption sites with substantial difference in energy of adsorption. According to Dubinin-Radushkevich adsorption isotherm model, physical-ion exchange mechanism was suggested for the adsorption of 1-H organic cation and both physical and chemical-ion exchange mechanisms were suggested for the adsorption of 2-OH and 3-OCH3 organic cations

  10. CO 2 adsorption in mono-, di- and trivalent cation-exchanged metal-organic frameworks: A molecular simulation study

    KAUST Repository

    Chen, Yifei

    2012-02-28

    A molecular simulation study is reported for CO 2 adsorption in rho zeolite-like metal-organic framework (rho-ZMOF) exchanged with a series of cations (Na +, K +, Rb +, Cs +, Mg 2+, Ca 2+, and Al 3+). The isosteric heat and Henry\\'s constant at infinite dilution increase monotonically with increasing charge-to-diameter ratio of cation (Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ < Al 3+). At low pressures, cations act as preferential adsorption sites for CO 2 and the capacity follows the charge-to-diameter ratio. However, the free volume of framework becomes predominant with increasing pressure and Mg-rho-ZMOF appears to possess the highest saturation capacity. The equilibrium locations of cations are observed to shift slightly upon CO 2 adsorption. Furthermore, the adsorption selectivity of CO 2/H 2 mixture increases as Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ ≈ Al 3+. At ambient conditions, the selectivity is in the range of 800-3000 and significantly higher than in other nanoporous materials. In the presence of 0.1% H 2O, the selectivity decreases drastically because of the competitive adsorption between H 2O and CO 2, and shows a similar value in all of the cation-exchanged rho-ZMOFs. This simulation study provides microscopic insight into the important role of cations in governing gas adsorption and separation, and suggests that the performance of ionic rho-ZMOF can be tailored by cations. © 2012 American Chemical Society.

  11. Computer simulation of methanol exchange dynamics around cations and anions

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Santanu; Dang, Liem X.

    2016-03-03

    In this paper, we present the first computer simulation of methanol exchange dynamics between the first and second solvation shells around different cations and anions. After water, methanol is the most frequently used solvent for ions. Methanol has different structural and dynamical properties than water, so its ion solvation process is different. To this end, we performed molecular dynamics simulations using polarizable potential models to describe methanol-methanol and ion-methanol interactions. In particular, we computed methanol exchange rates by employing the transition state theory, the Impey-Madden-McDonald method, the reactive flux approach, and the Grote-Hynes theory. We observed that methanol exchange occurs at a nanosecond time scale for Na+ and at a picosecond time scale for other ions. We also observed a trend in which, for like charges, the exchange rate is slower for smaller ions because they are more strongly bound to methanol. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.

  12. Cation exchange resin nanocomposites based on multi-walled carbon nanotubes

    Science.gov (United States)

    Fathy, Mahmoud; Abdel Moghny, Th.; Awad Allah, Ahmed Elsayed; Alblehy, AbdElhamid

    2014-01-01

    Carbon nanotubes (CNTs) are of great interest due to their potential applications in different fields such as water treatment and desalination. The increasing exploitation of multi-walled carbon nanotubes (MWCNTs) into many industrial processes has raised considerable concerns for environmental applications. The interactions of soluble salt with MWNCTs influence in the total salt content in saline water. In this work, we synthesized two cation exchange resins nano composites from polystyrene divinylbenzene copolymer (PSDVB) and pristine MWNCTs. The prepared compounds were characterized using infra red spectroscopy, thermal stability, X-ray diffraction, and electro scan microscope. Also, the ion capacities of prepared cation exchange resins were determined by titration. Based on the experimental results, it was found that the thermal stability of prepared nanocomposites in the presence of MWNCTs increased up to 617 °C. The X-ray of PSDVB and its sulfonated form exhibits amorphous pattern texture structure, whereas the nano composite exhibits amorphous structure with indication peak at 20° and 26° for the PSDVB and MWCNTs, respectively. The ion-exchange capacity increased from 225.6 meq/100 g to 466 mg/100 g for sulfonated PSDVB and sulfonated PSDVB MWNCTs-pristine, respectively.

  13. Synthesis and rheological properties of cation-exchanged Laponite suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Phuoc, Tran X. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Univ. of Pittsburgh, PA (United States); Howard, Bret H. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Chyu, Minking K. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Univ. of Pittsburgh, PA (United States)

    2009-11-01

    In this paper we report our new approach to synthesize cation-exchanged Laponite suspensions. General observations of the prepared samples indicated that an aqueous suspension of 1 wt.% Laponite retained its free flowing liquid phase characteristics even after aging for several weeks. When bivalent cationic metals (Cu, Co, Ni) were ablated into the suspension, the strong charge of the crystal face was reduced and, on standing, the suspension gelled becoming highly viscous. This sol-gel transition was induced by the formation of a space-filled structure due to both van der Waals and electrostatic bonds between the positively charged rims and negatively charged faces. Rheological properties of such prepared suspensions were measured using a Brookfield DV-II Pro Viscometer with a small sample adapter (SSA18/13RPY). The yield strengths of 2.2 N/m2, 3.2 N/m2, and 1.7 N/m2 were measured for Ni-, Co-, and Cumodified Laponite suspensions, respectively. These yield strengths are sufficiently high for suspending weighting materials such as barite which requires the gel strength of about 0.5 N/m2.

  14. Synthesis and rheological properties of cation exchanged Laponite suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Tran, X P; Howard, B; Chyu, M K

    2009-01-01

    In this paper we report our new approach to synthesize cation-exchanged Laponite suspensions. General observations of the prepared samples indicated that an aqueous suspension of 1 wt% Laponite retained its free flowing liquid phase characteristics even after aging for several weeks. When bivalent cationic metals (Cu, Co, Ni) were ablated into the suspension, the strong charge of the crystal face was reduced and, on standing, the suspension gelled becoming highly viscous. This sol-gel transition was induced by the formation of a space-filled structure due to both van derWaals and electrostatic bonds between the positively charged rims and negatively charged faces. Rheological properties of such prepared suspensions were measured using a Brookfield DV-H Pro Viscometer with a small sample adapter{SSA18/13RPY). The yield strengths of2.2 N/m2, 3.2 N/m2, and 1.7 N/m2 were measured for Ni-, Co-, and Cu-modified Laponite suspensions, respectively. These yield strengths are sufficiently high for suspending weighting materials such as barite which requires the gel strength of about 0.5 N/m2.

  15. Synthesis, characterization and ion exchange properties of zirconium(IV) tungstoiodophosphate, a new cation exchanger

    Indian Academy of Sciences (India)

    Weqar Ahmad Siddiqui; Shakeel Ahmad Khan

    2007-02-01

    Zirconium(IV) tungstoiodophosphate has been synthesized under a variety of conditions. The most chemically and thermally stable sample is prepared by adding a mixture of aqueous solutions of 0.5 mol L-1 sodium tungstate, potassium iodate and 1 mol L-1 orthophosphoric acid to aqueous solution of 0.1 mol L-1 zirconium(IV) oxychloride. Its ion exchange capacity for Na+ and K+ was found to be 2.20 and 2.35 meq g-1 dry exchanger, respectively. The material has been characterized on the basis of chemical composition, pH titration, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis. The effect on the exchange capacity of drying the exchanger at different temperatures has been studied. The analytical importance of the material has been established by quantitative separation of Pb2+ from other metal ions.

  16. DETERMINATION OF ION EXCHANGE EQUILIBRIUM CONSTANTS FOR THE WEAK ACID CATION AND THE WEAK BASE ANION EXCHANGE RESINS

    Institute of Scientific and Technical Information of China (English)

    TAOZuyi; WANGChangshou

    1992-01-01

    The general procedure based on the potentiometric titration has developed.According to the procedure,the rational equilibrium constants of the ion exchange reactions RH/Na,RH/Ca,RH/Sr,RH/Ba for the weak acid cation exchange resin D725 and ROH/Cl for the weak base anion exchange resin D705 have been determined.

  17. Assessing the Sodium Exchange Capacity in Rainfed and Irrigated Soils in the Mediterranean Basin Using GIS

    Directory of Open Access Journals (Sweden)

    Luís Loures

    2017-03-01

    Full Text Available The soil exchange complex consists of colloidal materials on which ion exchange phenomena occur allowing it to attract, retain, and exchange elements that have opposite electric charges. Since their mineral constituents (clay and organic components (humus are mainly of a negative nature retained or exchanged ion are predominantly cations. Historically, failing to monitor parameters like the exchange sodium percentage (ESP has led to the permanent deterioration of soils which have become completely unproductive, largely reducing the sustainability of the agricultural systems. This study assesses how the sodium exchange capacity in irrigated soils differs from the rainfed ones through a sample survey that was carried out in the 15,031 ha of the Caia Irrigation Perimeter and adjacent areas, located in the municipalities of Elvas and Campo Maior, Portalegre District, Portugal where 14,280 georeferenced samples were collected from the top soil layer (0–20 cm, which were mixed 10 at a time so that each composite sample representing 11.1 ha. Then the samples were analyzed regarding the most relevant parameters for characterizing the soil exchange complex including the concentrations of exchanged bases and Cation Exchange Capacity (CEC. The results were arranged in a georeferenced grid with 1451 entries. Using classical statistical analysis and Geographic Information Systems (GIS software, it was possible to relate the individual soil samples analyzed with the cultural system practiced (irrigated or rainfed and the present soil group which permitted us to analyze the influence of the cultural system in the soil exchange complex. The distribution chart of the exchange sodium and CEC were created. The obtained results confirm a general decrease of CEC values and an increase of the exchangeable sodium content of irrigated explored soils when compared to the rainfed ones, putting forward noteworthy ideas not only regarding the necessary changes towards

  18. Fabrication of patterned calcium cross-linked alginate hydrogel films and coatings through reductive cation exchange.

    Science.gov (United States)

    Bruchet, Marion; Melman, Artem

    2015-10-20

    Calcium cross-linked alginate hydrogels are widely used in targeted drug delivery, tissue engineering, wound treatment, and other biomedical applications. We developed a method for preparing homogeneous alginate hydrogels cross-linked with Ca(2+) cations using reductive cation exchange in homogeneous iron(III) cross-linked alginate hydrogels. Treatment of iron(III) cross-linked alginate hydrogels with calcium salts and sodium ascorbate results in reduction of iron(III) cations to iron(II) that are instantaneously replaced with Ca(2+) cations, producing homogeneous ionically cross-linking hydrogels. Alternatively, the cation exchange can be performed by photochemical reduction in the presence of calcium chloride using a sacrificial photoreductant. This approach allows fabrication of patterned calcium alginate hydrogels through photochemical patterning of iron(III) cross-linked alginate hydrogel followed by the photochemical reductive exchange of iron cations to calcium.

  19. Simultaneous isolation of lactoferrin and lactoperoxidase from bovine colostrum by SPEC 70 SLS cation exchange resin.

    Science.gov (United States)

    Liang, Yafei; Wang, Xuewan; Wu, Mianbin; Zhu, Wanping

    2011-09-01

    In this work, simultaneous isolation of lactoferrin (Lf) and lactoperoxidase (Lp) from defatted bovine colostrum by one-step cation exchange chromatography with SPEC 70 SLS ion-exchange resin was investigated. A RP-HPLC method for Lf and Lp determination was developed and optimized as the following conditions: detection wavelength of 220 nm, flow rate of 1 mL/min and acetonitrile concentration from 25% to 75% within 20 min. The adsorption process of Lf on SPEC 70 SLS resin was optimized using Lf standard as substrate. The maximum static binding capacity of SPEC 70 SLS resin was of 22.0 mg/g resin at 15 °C, pH 7.0 and adsorption time 3 h. The Lf adsorption process could be well described by the Langmuir adsorption isotherm model, with a maximum adsorption capacity of 21.73 mg/g resin at 15 °C. In batch fractionation of defatted colostrum, the binding capacities of SPEC 70 SLS resin for adsorbing Lf and Lp simultaneously under the abovementioned conditions were 7.60 and 6.89 mg/g resin, respectively, both of which were superior to those of CM Sepharose F.F. or SP Sepharose F.F. resins under the same conditions. As a result, SPEC 70 SLS resin was considered as a successful candidate for direct and economic purification of Lf and Lp from defatted colostrum.

  20. Simultaneous Isolation of Lactoferrin and Lactoperoxidase from Bovine Colostrum by SPEC 70 SLS Cation Exchange Resin

    Directory of Open Access Journals (Sweden)

    Mianbin Wu

    2011-09-01

    Full Text Available In this work, simultaneous isolation of lactoferrin (Lf and lactoperoxidase (Lp from defatted bovine colostrum by one-step cation exchange chromatography with SPEC 70 SLS ion-exchange resin was investigated. A RP-HPLC method for Lf and Lp determination was developed and optimized as the following conditions: detection wavelength of 220 nm, flow rate of 1 mL/min and acetonitrile concentration from 25% to 75% within 20 min. The adsorption process of Lf on SPEC 70 SLS resin was optimized using Lf standard as substrate. The maximum static binding capacity of SPEC 70 SLS resin was of 22.0 mg/g resin at 15 °С, pH 7.0 and adsorption time 3 h. The Lf adsorption process could be well described by the Langmuir adsorption isotherm model, with a maximum adsorption capacity of 21.73 mg/g resin at 15 °С. In batch fractionation of defatted colostrum, the binding capacities of SPEC 70 SLS resin for adsorbing Lf and Lp simultaneously under the abovementioned conditions were 7.60 and 6.89 mg/g resin, respectively, both of which were superior to those of CM Sepharose F.F. or SP Sepharose F.F. resins under the same conditions. As a result, SPEC 70 SLS resin was considered as a successful candidate for direct and economic purification of Lf and Lp from defatted colostrum.

  1. Base cation deposition in Europe - Part II. Acid neutralization capacity and contribution to forest nutrition

    NARCIS (Netherlands)

    Draaijers, G.P.J.; Leeuwen, E.P. van; Jong, P.G.H. de; Erisman, J.W.

    1997-01-01

    An assessment was made of the capacity of base cations to neutralize acid deposition and of the contribution of base cation deposition to forest nutrition in Europe. In large parts of southern Europe more than 50% of the potential acid deposition was found counteracted by deposition of non-sea salt

  2. Is the clay "exchange capacity" concept wholly applicable to pozzolans?

    Directory of Open Access Journals (Sweden)

    Talero, R.

    2004-12-01

    Full Text Available One of the most characteristic properties of clays is their "cation exchange capacity", otherwise known as their "exchange capacity ". The research reported in this article shows that for various reasons some natural and artificial pozzolans exhibit this property. Ion exchange is only partial in the latter however because contrary to clays, on hydration with Portland cement, pozzolans may he nearly entirely converted from their mainly vitreous and/or amorphous original state into a variety of new more or less crystalline compounds. For this purpose a total of 142 types of cement were tested in this study: 8 industrial and 134 laboratory cements, the latter prepared by mixing Portland cements with different proportions, by weight, of three natural and three artificial pozzolans. All these cements were analysed by the Frattini test, 7 and/or 28 days after mixing. Both [OH-] and [CaO] and the percentage content of Na+ and K+ expressed as Na2O and K2O, respectively, were determined in liquid phase. The cation concentration was only determined for the 45 blended cements most relevant to the objective of the study. Finally, the three natural pozzolans were analyzed by XRD to identify their mineral composition. The results obtained confirmed the working hypothesis. They also showed that the higher the content of Na+ and/or K+ the higher the likelihood of exchange capacity in the pozzolans. in this case primarily with Ca2+ Nonetheless, the very special mineral composition of certain pozzolans, with minerals such as zeolite and phillipsite, may likewise contribute to this capacity. In any event, due to the cation exchange between Na+/ K+ and Ca+ the blended cements involved met the Frattini test requirements more readily and had shorter setting times, especially: - where the Portland cement with which they were mixed was not highly

  3. Full automation of {sup 68}Ga labelling of DOTA-peptides including cation exchange prepurification

    Energy Technology Data Exchange (ETDEWEB)

    Ocak, M. [Clinical Department of Nuclear Medicine, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Department of Pharmaceutical Technology, Pharmacy Faculty, Istanbul University, Istanbul (Turkey); Antretter, M. [Clinical Department of Nuclear Medicine, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Knopp, R.; Kunkel, F. [Eckert and Ziegler Eurotope GmbH, Berlin (Germany); Petrik, M. [Clinical Department of Nuclear Medicine, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Bergisadi, N. [Department of Pharmaceutical Technology, Pharmacy Faculty, Istanbul University, Istanbul (Turkey); Decristoforo, C. [Clinical Department of Nuclear Medicine, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria)], E-mail: Clemens.Decristoforo@uki.at

    2010-02-15

    Here we describe a fully automated approach for the synthesis of {sup 68}Ga-labelled DOTA-peptides based on pre-concentration and purification of the generator eluate by using a cation exchange-cartridge and its comparison with fully automated direct labelling applying fractionated elution. Pre-concentration of the eluate on a cation exchange cartridge both using a resin-based and a disposable cation-exchange cartridge efficiently removed {sup 68}Ge as well as major metal contaminations with Fe and Zn. This resulted in a high labelling efficiency of DOTA-peptides at high specific activity (SA) with short synthesis times.

  4. On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO2 Adsorption.

    Science.gov (United States)

    Pham, Trong D; Hudson, Matthew R; Brown, Craig M; Lobo, Raul F

    2017-03-09

    The CO2 adsorption properties of cation-exchanged Li-, Na-, K-, and Mg-ZK-5 zeolites were correlated to the molecular structures determined by Rietveld refinements of synchrotron powder X-ray diffraction patterns. Li-, K-, and Na-ZK-5 all exhibited high isosteric heats of adsorption (Qst ) at low CO2 coverage, with Na-ZK-5 having the highest Qst (ca. 49 kJ mol(-1) ). Mg(2+) was located at the center of the zeolite hexagonal prism with the cation inaccessible to CO2 , leading to a much lower Qst (ca. 30 kJ mol(-1) ) and lower overall uptake capacity. Multiple CO2 adsorption sites were identified at a given CO2 loading amount for all four cation-exchanged ZK-5 adsorbents. Site A at the flat eight-membered ring windows and site B/B* in the γ-cages were the primary adsorption sites in Li- and Na-ZK-5 zeolites. Relatively strong dual-cation adsorption sites contributed significantly to an enhanced electrostatic interaction for CO2 in all ZK-5 samples. This interaction gives rise to a migration of Li(+) and Mg(2+) cations from their original locations at the center of the hexagonal prisms toward the α-cages, in which they interact more strongly with the adsorbed CO2 .

  5. Analyzing freely dissolved concentrations of cationic surfactant utilizing ion-exchange capability of polyacrylate coated solid-phase microextraction fibers.

    Science.gov (United States)

    Chen, Yi; Droge, Steven T J; Hermens, Joop L M

    2012-08-24

    A 7-μm polyacrylate (PA) coated fiber was successfully employed to determine freely dissolved concentrations of cationic surfactants by solid-phase microextraction (SPME) and utilizing the capability of the PA-coating to sorb organic cations via ion-exchange at carboxylic groups. Measured fiber-water partitioning coefficients (K(fw)) were constant below a fiber loading of 2mmol per liter polyacrylate, allowing for simple and accurate analysis in a concentration range that is relevant from a risk assessment point of view. Ion-exchange was confirmed to be the main sorption mechanism because of a decreasing K(fw) with either higher CaCl(2) concentrations or lower pH, and maximum fiber uptake at the polyacrylate cation-exchange capacity (CEC, at 30mmol/L PA). Fiber-water sorption isotherms were established in various aqueous media in toxicological relevant concentrations. The developed SPME method has a high potential for application in ecotoxicological studies, as demonstrated in sorption studies with humic acid in different electrolyte solutions at aqueous concentrations down to the sub nM range. Cationic surfactant sorption affinities for humic acid also depend on medium composition but are orders of magnitude higher than to the PA fiber on a sorbent weight basis.

  6. Ammonia vapor sensing properties of polyaniline-titanium(IV)phosphate cation exchange nanocomposite.

    Science.gov (United States)

    Khan, Asif Ali; Baig, Umair; Khalid, Mohd

    2011-02-28

    In this study, the electrically conducting polyaniline-titanium(IV)phosphate (PANI-TiP) cation exchange nanocomposite was synthesized by sol-gel method. The cation exchange nanocomposite based sensor for detection of ammonia vapors was developed at room temperature. It was revealed that the sensor showed good reversible response towards ammonia vapors ranging from 3 to 6%. It was found that the sensor with p-toluene sulphonic acid (p-TSA) doped exhibited higher sensing response than hydrochloric acid doped. This sensor has detection limit ≤1% ammonia. The response of resistivity changes of the cation exchange nanocomposite on exposure to different concentrations of ammonia vapors shows its utility as a sensing material. These studies suggest that the cation exchange nanocomposite could be a good material for ammonia sensor at room temperature.

  7. Adsorptional removal of methylene blue by guar gum-cerium (IV) tungstate hybrid cationic exchanger.

    Science.gov (United States)

    Gupta, V K; Pathania, Deepak; Singh, Pardeep; Kumar, Amit; Rathore, B S

    2014-01-30

    Guar gum-cerium (IV) tungstate nanocomposite (GG/CTNC) cationic exchanger was synthesized using simple sol gel method. The GG/CTNC was characterized using X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectrophotometer (EDX). The XRD studies confirmed amorphous and fibrous in nature of GG/CTNC. The high percentage of oxygen in the nanocomposite material confirmed the functionality tungstate (WO4(-)). The ion exchange capacity of GG/CTNC for Na(+) ion was observed to be 1.30 mequivg(-1). The hybrid exchanger was used as potential adsorbent for the removal of methylene blue (MB) from aqueous system. The correlation coefficients value indicated a good fit of monolayer Langmuir model to the adsorption of methylene blue onto GG/CTNC. The adsorption kinetic study revealed that the adsorption process followed the pseudo second order kinetic. The Gibbs free energy (ΔG) values confirmed the spontaneous nature of adsorption process.

  8. Preparation of Medium Cation Exchange Stationary Phase of Polymeric Matrix and Their Chromatographic Properties

    Institute of Scientific and Technical Information of China (English)

    CHEN,Gang; GONG,Bo-Lin; BAI,Quan; GENG,Xin-Du

    2007-01-01

    Based on the monodisperse poly(glycidyl methacrylate-co-ethylenedimethacrylate) beads (PGMA/EDMA) with macropore as a medium, a new hydrophilic medium cation exchange (MCX) stationary phase for HPLC was synthesized by a new chemically modified method. The stationary phase was evaluated with the property of ion exchange, separability, reproducibility, hydrophilicity, effect of salt concentration, salt types, column loading and pH on the separation and retention of proteins in detail. It was found that it follows ion exchange chromatographic (IEC)retention mechanism. The measured bioactivity recovery for lysozyme was (96±5)%. The dynamic protein loading capacity of the synthesized MCX packings was 21.8 mg/g. Five proteins were almost completely separated within 6.0 min at a flow rate of 4 mL/min using the synthesized MCX resin. The MCX resin was also used for the rapid separation and purification of lysozyme from egg white with only one step. The purity and specific bioactivity of the purified lysozyme was found more than 95% and 70345 U/mg, respectively.

  9. Cation exchange at the secondary building units of metal–organic frameworks

    OpenAIRE

    Brozek, Carl Kavanaugh; Dinca, Mircea

    2014-01-01

    Cation exchange is an emerging synthetic route for modifying the secondary building units (SBUs) of metal–organic frameworks (MOFs). This technique has been used extensively to enhance the properties of nanocrystals and molecules, but the extent of its applications for MOFs is still expanding. To harness cation exchange as a rational tool, we need to elucidate its governing factors. Not nearly enough experimental observations exist for drawing these conclusions, so we provide a conceptual fra...

  10. Sorption of Ni(II) ions from aqueous solution by Lewatit cation-exchange resin.

    Science.gov (United States)

    Dizge, Nadir; Keskinler, Bülent; Barlas, Hulusi

    2009-08-15

    Ion-exchange is an alternative process for uptake of heavy metals from aqueous solutions. In the present study, the sorption of nickel(II) ions from aqueous solution was investigated by using Lewatit MonoPlus SP 112 (strongly acidic, macroporous cation-exchange resin) in a batch adsorption system as a function of pH (2.0-8.0), initial nickel concentration (50-200 mg/L), resin dosage (0.5-2.0 g/L), contact time (0.5-3h), and temperatures (298-318K). The data were analyzed on the basis of Lagergren pseudo-first order, pseudo-second order (Types 1-5), Elovich and external, Weber-Morris intraparticle, pore-surface mass diffusion models. The experimental data showed that the maximum pH for efficient sorption of nickel(II) was 6.0. At the optimal conditions, nickel(II) ions sorption on the resin was decreased when the initial metal concentration increased. The results indicated that the resin dosage strongly affected the amount of nickel(II) ions removed from aqueous solution. The adsorption process was very fast due to 80% of nickel(II) sorption was occurred within 30 min and equilibrium was reached at about 90 min. Freundlich and Langmuir adsorption isotherm models were used for sorption equilibrium data and the maximum adsorption capacity (171 mg/g) of Lewatit MonoPlus SP 112 was obtained from Langmuir isotherm. The thermodynamic parameters (DeltaG degrees, free energy change; DeltaS degrees, enthalpy change; and DeltaH degrees, entropy change) for sorption of nickel(II) ions were evaluated. The rise in temperature caused a partly increase in the value of the equilibrium constant (K(c)) for the sorption of nickel(II) ions. Moreover, column flow adsorption study was also studied. Breakthrough curves were obtained from column flow studies by using both synthetic solution and rinsing bath water of filter industry. The column regeneration was carried out for two sorption-desorption cycles. The eluant used for regeneration of the cation-exchange resin was 7% (w/w) HCl. The

  11. Modification of the cation exchange resin properties by impregnation in polyethyleneimine solutions: application to the separation of metallic ions.

    Science.gov (United States)

    Amara, Mourad; Kerdjoudj, Hacène

    2003-07-27

    A commercial cation exchange resin Amberlite 200 has been modified after immersion in solutions of polyethyleneimine (PEI). The kinetic of fixation of the metallic ions have been determined. The modification of the surface of the resin deals with a change in the order of the affinities of the resins towards cations. The retention is the function of the formation and the stability of the complex. The conditions of modification (pH, PEI concentration and time of immersion) have been examined and the modification was confirmed by the determination of the exchange capacities, the distribution coefficient (P) and the selectivity factors (S). The obtained results revealed the effect of PEI on the exchange properties of the resin. The pH range selected (6-8) permitted a good adherence of PEI onto the resin surface. The quantity of the adsorbed PEI was increased by raising the initial concentration and the immersion period. The exchange capacity for copper ion passed from 2.6 mmol g(-1), in the case of unmodified resin, to 3.9 mmol g(-1) for the modified one.

  12. Separation of Clay Minerals from Host Sediments Using Cation Exchange Resins

    Institute of Scientific and Technical Information of China (English)

    I.S. Ismael; H.M. Baioumy

    2003-01-01

    Classic physical and chemical treatments applied to separating clay minerals from the host sediments are often difficult or aggressive for clay minerals. A technique using cation exchange resins (amberlite IRC-50H and amberlite IR-120) is used to separate clay minerals from the host sediments. The technique is based on the exchange of cations in the minerals that may be associated clay minerals in sediments,such as Ca and Mg from dolomite; Ca from calcite,gypsum and francolite with cations carried by resin radicals. The associated minerals such as gypsum,calcite,dolomite and francolite are removed in descending order. Separation of clay minerals using cation exchange resins is less aggressive than that by other classic treatments.The efficiency of amberlite IRC-50H in the removal of associated minerals is greater than that of amberlite IR-120.

  13. Ion transport resistance in Microbial Electrolysis Cells with anion and cation exchange membranes

    NARCIS (Netherlands)

    Sleutels, T.H.J.A.; Hamelers, H.V.M.; Rozendal, R.A.; Buisman, C.J.N.

    2009-01-01

    Previous studies have shown that Microbial Electrolysis Cells (MECs) perform better when an anion exchange membrane (AEM) than when a cation exchange membrane (CEM) separates the electrode chambers. Here, we have further studied this phenomenon by comparing two analysis methods for bio-electrochemic

  14. Exchangeable cations-mediated photodegradation of polycyclic aromatic hydrocarbons (PAHs) on smectite surface under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Hanzhong, E-mail: jiahz@ms.xjb.ac.cn [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Li, Li [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Chen, Hongxia; Zhao, Yue [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); School of Geology and Mining Engineering, Xinjiang University, Urumqi 830046 (China); Li, Xiyou [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Wang, Chuanyi, E-mail: cywang@ms.xjb.ac.cn [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China)

    2015-04-28

    Graphical abstract: Roles of exchangeable cations in PAHs photodegradation on clay surafces under visible light. - Highlights: • Photolysis rate are strongly dependent on the type of cations on clay surface. • The strength of “cation–π” interactions governs the photodegradation rate of PAHs. • Several exchangeable cations could cause a shift in the absorption spectrum of PAHs. • Exchangeable cations influence the type and amount of reactive intermediates. - Abstract: Clay minerals saturated with different exchangeable cations are expected to play various roles in photodegradation of polycyclic aromatic hydrocarbons (PAHs) via direct and/or indirect pathways on clay surfaces. In the present study, anthracene and phenanthrene were selected as molecule probes to investigate the roles of exchangeable cations on their photodegradation under visible light irradiation. For five types of cation-modified smectite clays, the photodegradation rate of anthracene and phenanthrene follows the order: Fe{sup 3+} > Al{sup 3+} > Cu{sup 2+} >> Ca{sup 2+} > K{sup +} > Na{sup +}, which is consistent with the binding energy of cation–π interactions between PAHs and exchangeable cations. The result suggests that PAHs photolysis rate depends on cation–π interactions on clay surfaces. Meanwhile, the deposition of anthracene at the Na{sup +}-smectite and K{sup +}-smectite surface favors solar light absorption, resulting in enhanced direct photodecomposition of PAHs. On the other hand, smectite clays saturated with Fe{sup 3+}, Al{sup 3+}, and Cu{sup 2+} are highly photoreactive and can act as potential catalysts giving rise to oxidative radicals such as O{sub 2}{sup −}· , which initiate the transformation of PAHs. The present work provides valuable insights into understanding the transformation and fate of PAHs in the natural soil environment and sheds light on the development of technologies for contaminated land remediation.

  15. Preparation of weak cation exchange packings for chromatographic separation of proteins using "click chemistry''.

    Science.gov (United States)

    Zhao, Kailou; Bai, Quan; Song, Chao; Wang, Fei; Yang, Fan

    2012-04-01

    "Click chemistry" is defined as a class of robust and selective chemical reactions affording high yields and is tolerant to a variety of solvents (including water), functional groups, and air. In this study, click chemistry was used as an effective strategy for coupling three alkyne-carboxylic acids onto the azide-silica to obtain three novel stationary phases of weak cation exchange chromatography, which were characterized with FTIR and elemental analysis. Six kinds of standard proteins, such as myoglobin, RNase A, RNase B, cytochrome C, α-chymotrypsin A, and lysozyme, were separated completely with the three novel weak cation exchange chromatography stationary phases. Compared with commercial weak cation exchange chromatography columns, the three kinds of novel weak cation exchange chromatography packings prepared by click chemistry approach have better resolution and selectivity. The mass recovery of more than 97% was obtained for all the tested proteins, and the bioactivity recovery of lysozyme on the prepared column was determined to be 96%. In addition, lysozyme was purified successfully from egg white with the novel weak cation exchange chromatography column by one step. The purity was more than 97% and a high specific activity was achieved to be 81 435 U/mg. The results illustrate the potential of click chemistry for preparing stationary phase for ion-exchange chromatography.

  16. Safety evaluation of cation-exchange resins. [For use in separating and processing radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Kalkwarf, D.R.

    1977-08-01

    Results are presented of a study to evaluate whether sufficient information is available to establish conservative limits for the safe use of cation-exchange resins in separating radionuclides and, if not, to recommend what new data should be acquired. The study was also an attempt to identify in-line analytical techniques for the evaluation of resin degradation during radionuclide processing. The report is based upon a review of the published literature and upon discussions with many people engaged in the use of these resins. It was concluded that the chief hazard in the use of cation-exchange resins for separating radionuclides is a thermal explosion if nitric acid or other strong oxidants are present in the process solution. Thermal explosions can be avoided by limiting process parameters so that the rates of heat and gas generation in the system do not exceed the rates for their transfer to the surroundings. Such parameters include temperature, oxidant concentration, the amounts of possible catalysts, the radiation dose absorbed by the resin and the diameter of the resin column. Current information is not sufficient to define safe upper limits for these parameters. They can be evaluated, however, from equations derived from the Frank-Kamenetskii theory of thermal explosions provided the heat capacities, thermal conductivities and rates of heat evolution in the relevant resin-oxidant mixtures are known. It is recommended that such measurements be made and the appropriate limits be evaluated. A list of additional safety precautions are also presented to aid in the application of these limits and to provide additional margins of safety. In-line evaluation of resin degradation to assess its safety hazard is considered impractical. Rather, it is recommended that the resin be removed from use before it has received the limiting radiation dose, evaluated as described above.

  17. Ultrathin Sicopion Composite Cation-Exchange Membranes: Characteristics and Electrodialytic Performance following a Conditioning Procedure

    Directory of Open Access Journals (Sweden)

    Erik Ayala-Bribiesca

    2012-01-01

    Full Text Available The aim of this work was to investigate the properties of Sicopion membranes: an ultrathin (≈20 μm composite cation-exchange membrane (CEM made from sulphonated poly(ether-ether-ketone (SPEEK containing different levels of sulphonic-functionalized silica particles (SFSPs. Sicopion membranes were conditioned according to the French Normalization Association procedure, consisting in a series of acid and alkaline washes, and their electrodialytic characteristics were compared to an existent commercial food-grade membrane (CMX-SB. Electrical conductivity of Sicopion membranes was higher than that of CMX-SB membranes (9.92 versus 6.98 mS/cm, as well as their water content (34.0 versus 27.6%. As the SFSP level was reduced, the ion-exchange capacity (IEC of Sicopion membranes increased. Concerning their electrodialytic performances, Sicopion membranes presented a lower demineralization rate than CMX-SB membranes (35.9 versus 45.5%, due to an OH− leakage through the pores created by dislodging the SFSP particles during the conditioning procedure.

  18. INTRAPARTICLE DIFFUSION OF RARE EARTHS IN POROUS CATION EXCHANGERS

    Institute of Scientific and Technical Information of China (English)

    LINGDaren; ZHENGZuying; 等

    1993-01-01

    Experiments for determining cerium isotope ion exchange rates with macroporous resins Amberlyst 15,D001 and XN1010 are discribed.The kinetics of the isotope ion exchange reaction has been examined by a simple theoretical equation of intraparticle effective diffustivity De in a porous ion exchanger.The ion exchange proceedes by diffusion within the macropores and the solid phase of the resin,De of cerium was affected by the concentration of the bulk solution C and was separated into a macropore diffusivity D-p and a solid phase diffusivity D-g by the equation.The diffusion coefficients of the exchanging ion are shown to have the values in the macropores comparable with those in the bulk solution and to have the values in the solid phase comparable with those in gel resin with the same crosslinkage as the resins used for the experiments.

  19. Isolation of lactoperoxidase using different cation exchange resins by batch and column procedures.

    Science.gov (United States)

    Fweja, Leonard Wt; Lewis, Michael J; Grandison, Alistair S

    2010-08-01

    Lactoperoxidase (LP) was isolated from whey protein by cation-exchange using Carboxymethyl resin (CM-25C) and Sulphopropyl Toyopearl resin (SP-650C). Both batch and column procedures were employed and the adsorption capacities and extraction efficiencies were compared. The resin bed volume to whey volume ratios were 0.96:1.0 for CM-25C and 0.64:1.0 for SP-650 indicating higher adsorption capacity of SP-650 compared with CM-25C. The effluent LP activity depended on both the enzyme activity in the whey and the amount of whey loaded on the column within the saturation limits of the resin. The percentage recovery was high below the saturation point and fell off rapidly with over-saturation. While effective recovery was achieved with column extraction procedures, the recovery was poor in batch procedures. The whey-resin contact time had little impact on the enzyme adsorption. SDS PAGE and HPLC analyses were also carried out, the purity was examined and the proteins characterised in terms of molecular weights. Reversed phase HPLC provided clear distinction of the LP and lactoferrin (LF) peaks. The enzyme purity was higher in column effluents compared with batch effluents, judged on the basis of the clarity of the gel bands and the resolved peaks in HPLC chromatograms.

  20. Sulfonated hydrocarbon graft architectures for cation exchange membranes

    DEFF Research Database (Denmark)

    Nielsen, Mads Møller; Jankova Atanasova, Katja; Hvilsted, Søren

    2013-01-01

    A synthetic strategy to hydrocarbon graft architectures prepared from a commercial polysulfone and aimed as ion exchange membrane material is proposed. Polystyrene is grafted from a polysulfone macroinitiator by atom transfer radical polymerization, and subsequently sulfonated with acetyl sulfate...

  1. Synthesis and adsorption properties of the cation exchange forms of OFF-type zeolite

    Science.gov (United States)

    Gorshunova, K. K.; Travkina, O. S.; Kustov, L. M.; Kutepov, B. I.

    2016-03-01

    The possibility of the ion-exchange of Na+ and K+ cations contained in OFF-type zeolite for H+, Ni2+, Cu2+, Co2+, and La3+ cations is investigated. Chemical and phase compositions, the morphology of crystals, and the adsorption properties of synthesized samples are studied via X-ray fluorescence and X-ray diffraction analysis, IR spectroscopy, scanning electron microscopy, and adsorption measurements.

  2. Sulphonic acid strong cation-exchange restricted access columns in sample cleanup for profiling of endogenous peptides in multidimensional liquid chromatography. Structure and function of strong cation-exchange restricted access materials.

    Science.gov (United States)

    Machtejevas, E; Denoyel, R; Meneses, J M; Kudirkaite, V; Grimes, B A; Lubda, D; Unger, K K

    2006-08-04

    In this work, the pore structural parameters and size exclusion properties of LiChrospher strong cation-exchange and reverse phase restricted access materials (RAM) are analysed. The molecular weight size exclusion limit for polystyrenes was found to be about 17.7 kDa, while for standard proteins, the molecular weight size exclusion limit was higher, at approximately 25 kDa. The average pore diameter on a volume basis calculated from the pore network model changes from 8.5 nm (native LiChrospher) to 8.6 nm (diol derivative) to 8.2 nm (sulphonic acid derivative) to 6.9 nm (n-octadecyl derivative). Additional characterisations were performed on restricted access materials with nitrogen sorption at 77 K, water adsorption at 25 degrees C, intrusion-extrusion of water (in order to evaluate the hydrophobic properties of the pores of the hydrophobic RAM), and zeta potential measurements by microelectrophoresis. For peptide analysis out of the biofluids, the strong cation-exchange functionality seems to be particularly suitable mainly because of the high loadability of the strong cation-exchange restricted access material (SCX-RAM) and the fact that one can work under non-denaturing conditions to perform effective chromatographic separations. For bacitracin, the dynamic capacity of the SCX-RAM columns does not reach its maximum value in the analysed range. For lysozyme, the dynamic capacity reaches a value of 0.08 mg/ml of column volume before column is overloaded. Additionally, the proper column operating conditions that lead to the total effective working time of the RAM column to be equal to approximately 500 injections (depending on the type of sample), is comprehensively described. The SCX-RAM column was used in the same system analysing urine samples for the period of 1 month (approximately 150 injections) with run-to-run reproducibility below 5% RSD and below 10% RSD for the relative fractions.

  3. On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO 2 Adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Trong D. [Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA; Hudson, Matthew R. [Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg Maryland 20899 USA; Brown, Craig M. [Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA; Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg Maryland 20899 USA; Lobo, Raul F. [Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA

    2017-02-16

    The CO2 adsorption properties of cation-exchanged Li-, Na-, K-, and Mg-ZK-5 zeolites were correlated to the molecular structures determined by Rietveld refinements of synchrotron powder X-ray diffraction patterns. Li-, K-, and Na-ZK-5 all exhibited high isosteric heats of adsorption (Qst) at low CO2 coverage, with Na-ZK-5 having the highest Qst (ca. 49 kJ mol-1). Mg2+ was located at the center of the zeolite hexagonal prism with the cation inaccessible to CO2, leading to a much lower Qst (ca. 30 kJ mol-1) and lower overall uptake capacity. Multiple CO2 adsorption sites were identified at a given CO2 loading amount for all four cation-exchanged ZK-5 adsorbents. Site A at the flat eight-membered ring windows and site B/B* in the γ-cages were the primary adsorption sites in Li- and Na-ZK-5 zeolites. Relatively strong dual-cation adsorption sites contributed significantly to an enhanced electrostatic interaction for CO2 in all ZK-5 samples. This interaction gives rise to a migration of Li+ and Mg2+ cations from their original locations at the center of the hexagonal prisms toward the α-cages, in which they interact more strongly with the adsorbed CO2.

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

    Directory of Open Access Journals (Sweden)

    DRAGAN STOJSIC

    2001-08-01

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

  5. Protein adsorption in polyelectrolyte brush type cation-exchangers.

    Science.gov (United States)

    Khalaf, Rushd; Coquebert de Neuville, Bertrand; Morbidelli, Massimo

    2016-11-04

    Ion exchange chromatography materials functionalized with polyelectrolyte brushes (PEB) are becoming an integral part of many protein purification steps. Adsorption onto these materials is different than that onto traditional materials, due to the 3D partitioning of proteins into the polyelectrolyte brushes. Despite this mechanistic difference, many works have described the chromatographic behavior of proteins on polyelectrolyte brush type ion exchangers with much of the same methods as used for traditional materials. In this work, unconventional chromatographic behavior on polyelectrolyte brush type materials is observed for several proteins: the peaks shapes reveal first anti-Langmuirian and then Langmuirian types of interactions, with increasing injection volumes. An experimental and model based description of these materials is carried out in order to explain this behavior. The reason for this behavior is shown to be the 3D partitioning of proteins into the polyelectrolyte brushes: proteins that fully and readily utilize the 3D structure of the PEB phase during adsorption show this behavior, whereas those that do not show traditional ion exchange behavior.

  6. Time reversal and exchange symmetries of unitary gate capacities

    CERN Document Server

    Harrow, A W; Harrow, Aram W.; Shor, Peter W.

    2005-01-01

    Unitary gates are an interesting resource for quantum communication in part because they are always invertible and are intrinsically bidirectional. This paper explores these two symmetries: time-reversal and exchange of Alice and Bob. We will present examples of unitary gates that exhibit dramatic separations between forward and backward capacities (even when the back communication is assisted by free entanglement) and between entanglement-assisted and unassisted capacities, among many others. Along the way, we will give a general time-reversal rule for relating the capacities of a unitary gate and its inverse that will explain why previous attempts at finding asymmetric capacities failed. Finally, we will see how the ability to erase quantum information and destroy entanglement can be a valuable resource for quantum communication.

  7. Adsorption behavior and mechanism of cadmium on strong-acid cation exchange resin

    Institute of Scientific and Technical Information of China (English)

    WANG Fei; WANG Lian-jun; LI Jian-sheng; SUN Xiu-yun; HAN Wei-qing

    2009-01-01

    The adsorption behavior of Cd2+ on 001×7 strong-acid cation exchange resin was studied with the static adsorption method. The adsorption process was analyzed from thermodynamics and kinetics aspects. The influences of experimental parameters such as pH, temperature, initial concentration and adsorption rate were investigated. The experimental results show that in the studied concentration range, 001×7 resin has a good sorption ability for Cd2+, and the equilibrium adsorption data fit to Freundlich isotherms. The adsorption is an exothermic process which runs spontaneously. Kinetic analysis shows that the adsorption rate is mainly governed by liquid film diffusion. The best adsorption condition is pH 4-5. The saturated resin can be regenerated by 3 mol/L nitric acid, and the desorption efficiency is over 98%. The maximal static saturated adsorption capacity is 355 mg/g (wet resin) at 293 K. The adsorption mechanism of Cd2+ on 001×7 resin was discussed based on IR spectra.

  8. The Metal Cation Chelating Capacity of Astaxanthin. Does This Have Any Influence on Antiradical Activity?

    Directory of Open Access Journals (Sweden)

    Ana Martínez

    2012-01-01

    Full Text Available In this Density Functional Theory study, it became apparent that astaxanthin (ASTA may form metal ion complexes with metal cations such as Ca+2, Cu+2, Pb+2, Zn+2, Cd+2 and Hg+2. The presence of metal cations induces changes in the maximum absorption bands which are red shifted in all cases. Therefore, in the case of compounds where metal ions are interacting with ASTA, they are redder in color. Moreover, the antiradical capacity of some ASTA-metal cationic complexes was studied by assessing their vertical ionization energy and vertical electron affinity, reaching the conclusion that metal complexes are slightly better electron donors and better electron acceptors than ASTA.

  9. Alkali recovery using PVA/SiO2 cation exchange membranes with different -COOH contents.

    Science.gov (United States)

    Hao, Jianwen; Gong, Ming; Wu, Yonghui; Wu, Cuiming; Luo, Jingyi; Xu, Tongwen

    2013-01-15

    By changing -COOH content in poly(acrylic acid-co-methacryloxypropyl trimethoxy silane (poly(AA-co-γ-MPS)), a series of PVA/SiO(2) cation exchange membranes are prepared from sol-gel process of poly(AA-co-γ-MPS) in presence of poly(vinyl alcohol) (PVA). The membranes have the initial decomposition temperature (IDT) values of 236-274 °C. The tensile strength (TS) ranges from 17.4 MPa to 44.4 MPa. The dimensional stability in length (DS-length) is in the range of 10%-25%, and the DS-area is in the range of 21%-56% in 65 °C water. The water content (W(R)) ranges from 61.2% to 81.7%, the ion exchange capacity (IEC) ranges from 1.69 mmol/g to 1.90 mmol/g. Effects of -COOH content on diffusion dialysis (DD) performance also are investigated for their potential applications. The membranes are tested for recovering NaOH from the mixture of NaOH/Na(2)WO(4) at 25 - 45 °C. The dialysis coefficients of NaOH (U(OH)) are in the range of 0.006-0.032 m/h, which are higher than those of the previous membranes (U(OH): 0.0015 m/h, at 25 °C). The selectivity (S) can reach up to 36.2. The DD performances have been correlated with the membrane structure, especially the continuous arrangement of -COOH in poly(AA-co-γ-MPS) chain.

  10. A method for the production of weakly acidic cation exchange resins

    Science.gov (United States)

    Heller, H.; Werner, F.; Mitschker, A.; Diehl, H. V.; Schaefer, A.

    1991-12-01

    The invention relates to a nonpolluting method for the production of weakly acidic cation exchange resins by saponification of cross-linked acrylonitrile bead polymers, with an alkaline saponification agent at elevated temperature, according to which method the bead polymer and alkaline saponification agent are jointly added only at elevated temperature.

  11. Synthesis and cation-exchange properties of a bis-zwitterionic lamellar hybrid material

    Energy Technology Data Exchange (ETDEWEB)

    Besson, E. [ICSM Marcoule, UMR 5257, F-30207 Bagnols Sur Ceze, (France); Mehdi, A.; Reye, C.; Corriu, Robert J. P. [Univ Montpellier 2, Inst Charles Gerhardt Montpellier, CNRS-UM2-ENSCM-UM1, UMR 5253, Chim Mol et Org Sol, F-34095 Montpellier 5, (France); Chollet, H. [CEA Valduc, Dept Traitement Mat Nucl, F-21120 Is Sur Tille, (France); Guilard, R. [ICMUB, CNRS, UMR 5260, F-21078 Dijon, (France)

    2008-07-01

    The synthesis of a bis-zwitterionic lamellar hybrid material containing ammonium carboxylate groups is described. Cation-exchange properties of this material towards transition metal and lanthanide ions were studied as well as the regeneration and reuse of the material. (authors)

  12. Nongeminate Radiative Recombination of Free Charges in Cation-Exchanged PbS Quantum Dot Films

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Ashley R.; Beard, Matthew C.; Johnson, Justin C.

    2016-06-01

    Using photoluminescence (PL) spectroscopy we explore the radiative recombination pathways in PbS quantum dots (QDs) synthesized by two methods. We compare conventionally synthesized PbS from a PbO precursor to PbS synthesized using cation-exchange from CdS QDs. We show that strongly coupled films of PbS QDs from the cation-exchange luminesce with significant efficiency at room temperature. This is in stark contrast to conventional PbS QDs, which have exceedingly weak room temperature emission. Moreover, the power dependence of the emission is quadratic, indicating bimolecular radiative recombination that is reasonably competitive with trap-assisted recombination, a feature previously unreported in coupled PbS QD films. We interpret these results in terms of a greatly reduced defect concentration for cation-exchanged QDs that mitigates the influence of trap-assisted recombination. Cation-exchanged QDs have recently been employed in highly efficient and air-stable lead chalcogenide QD devices, and the reduced number of trap states inferred here may lead to improved current collection and higher open circuit voltage.

  13. Behavior of human serum albumin on strong cation exchange resins: I. experimental analysis.

    Science.gov (United States)

    Voitl, Agnes; Butté, Alessandro; Morbidelli, Massimo

    2010-08-20

    Experiments with human serum albumin on the strong cation exchange resin Fractogel EMD SE Hicap (M) were carried out. Even though human serum albumin was used at high purity, two peaks in gradient elution experiments occurred. The obtained data can be explained by considering that human serum albumin binds to Fractogel EMD SE Hicap (M) in two different binding conformations: the protein adsorbs instantaneously in the first conformation and then changes into the second one with a kinetic limitation. The two-peak behavior of human serum albumin was analyzed in detail, especially at various gradient lengths, concentrations and temperatures. Breakthrough curves were performed at four modifier concentrations and three velocities. The characteristic adsorption behavior, found for gradient experiments, was confirmed by the breakthrough curves. The two-peak elution pattern of human serum albumin was also found for other strong cation exchange resins, but not for weak cation exchange resins. It is concluded that the described behavior is peculiar for the interaction of human serum albumin with the strong cation exchange ligand of the resin.

  14. Selective separation of sodium ions from a mixture with phenylalanine by Donnan dialysis with a profiled sulfogroup cation exchange membrane

    Science.gov (United States)

    Vasil'eva, V. I.; Goleva, E. A.

    2013-11-01

    The possibility of separating ions of metal from a mixture with ampholyte (an amino acid) by Donnan dialysis with an MK-40 sulfogroup cation exchange membrane is demonstrated. Conditions ensuring the selectivity and intensity of the mass transfer of sodium ions from a mixture with bipolar phenylalanine ions into a diffusate containing hydrochloric acid through a cation exchange membrane are found.

  15. Calcium Solubility and Cation Exchange Properties in Zeoponic Soil

    Science.gov (United States)

    Beiersdorfer, Raymond E.

    1999-01-01

    An important aspect of a regenerative life support system at a Lunar or Martian outpost is the ability to produce food. Essential plant nutrients, as well as a solid support substrate, can be provided by: (1) treated Lunar or Martian regolith; (2) a synthetic soil or (3) some combination of both. A synthetic soil composed of ammonium- and potassium-saturated chinoptlolite (a zeolite mineral) and apatite, can provide slow-release fertilization of plants via dissolution and ion-exchange reactions. Previous equilibrium studies (Beiersdorfer, 1997) on mixtures of synthetic hydroxyapatite and saturated-clinoptilolite indicate that the concentrations of macro-nutrients such as ammonium, phosphorous, potassium, magnesium, and calcium are a function of the ratio of chinoptilolite to apatite in the sample and to the ratio of potassium to ammonium on the exchange sites in the clinoptilolite. Potassium, ammonium, phosphorous, and magnesium are available to plants at sufficient levels. However, calcium is deficient, due to the high degree of calcium adsorption by the clinoptilolite. Based on a series of batch-equilibration experiments, this calcium deficiency can be reduced by (1) treating the clinoptilolite with CaNO3 or (2) adding a second Ca-bearing mineral (calcite, dolomite or wollastonite) to the soil. Treating the Cp with CaNO3 results in increased Ca in solution, decreased P in solution and decreased NH4 in solution. Concentrations of K were not effected by the CaNO3 treatment. Additions of Cal, Dol and Wol changed the concentrations of Ca and P in solution in a systematic fashion. Cal has the greatest effect, Dol the least and Wol is intermediate. The changes are consistent with changes expected for a common ion effect with Ca. Higher concentrations of Ca in solution with added Cal, Dol or Wol do not result in changes in K or NH4 concentrations.

  16. Surface-orientation-dependent distribution of subsurface cation-exchange defects in olivine-phosphate nanocrystals.

    Science.gov (United States)

    Chung, Sung-Yoon; Choi, Si-Young; Kim, Tae-Hwan; Lee, Seongsu

    2015-01-27

    Atomic-scale exchange between two different cations of similar size in crystalline oxides is one of the major types of point defects when multiple cations in oxygen interstitials are arrayed in an ordered manner. Although a number of studies have been performed on a variety of Li-intercalation olivine phosphates to determine the distribution of exchange defects in bulk, understanding of the thermodynamic stability of the defects in subsurface regions and its dependency on the crystallographic orientation at the surface has remained elusive. Through a combination of small-angle neutron scattering, atomic-scale direct probing with scanning transmission electron microscopy, and theoretical ab initio calculations, we directly demonstrate that the antisite exchange defects are distributed in a highly anisotropic manner near the surfaces of LiFePO4 crystals. Moreover, a substantial amount of cation exchanges between Li and Fe sites is identified as an energetically favorable configuration in some surface regions, showing excellent agreement with the calculation results of negative defect formation energies. The findings in this study provide insight into developing better ways to avoid degradation of lithium mobility through the surface as well as scientifically notable features regarding the distribution of exchange defects in olivine phosphates.

  17. Strong cation exchange monoliths for HPLC by Reactive Gelation.

    Science.gov (United States)

    Brand, Bastian; Krättli, Martin; Storti, Giuseppe; Morbidelli, Massimo

    2011-08-01

    Polymeric monolithic stationary phases for HPLC can be produced by Reactive Gelation. Unlike the conventional method of using porogens, such novel process consists of a number of separate steps, thus enabling a better control of the quality of the final material. A suspension of polymer nanoparticles in water is produced and subsequently swollen with hydrophobic monomers. The particles are then destabilised (usually by salt addition) to make them aggregate into a large percolating structure, the so-called monolith. Finally, the added monomer can then be polymerised to harden the structure. In this work, a polystyrene latex is used as the base material and functionalised by introduction of epoxide groups on the surface and subsequent reaction to sulphonic acid groups, yielding a SO3(-) density of 0.7 mmol/g dry material. Morphological investigations show 54% porosity made of 300 nm large pores. Van Deemter measurements of a large protein show no practical influence of diffusion limitations on the plate number. Finally, a preliminary separation of a test protein mixture is shown, demonstrating the potential of using ion-exchange chromatography on Reactive Gelation monoliths.

  18. First principles derived, transferable force fields for CO2 adsorption in Na-exchanged cationic zeolites.

    Science.gov (United States)

    Fang, Hanjun; Kamakoti, Preeti; Ravikovitch, Peter I; Aronson, Matthew; Paur, Charanjit; Sholl, David S

    2013-08-21

    The development of accurate force fields is vital for predicting adsorption in porous materials. Previously, we introduced a first principles-based transferable force field for CO2 adsorption in siliceous zeolites (Fang et al., J. Phys. Chem. C, 2012, 116, 10692). In this study, we extend our approach to CO2 adsorption in cationic zeolites which possess more complex structures. Na-exchanged zeolites are chosen for demonstrating the approach. These methods account for several structural complexities including Al distribution, cation positions and cation mobility, all of which are important for predicting adsorption. The simulation results are validated with high-resolution experimental measurements of isotherms and microcalorimetric heats of adsorption on well-characterized materials. The choice of first-principles method has a significant influence on the ability of force fields to accurately describe CO2-zeolite interactions. The PBE-D2 derived force field, which performed well for CO2 adsorption in siliceous zeolites, does not do so for Na-exchanged zeolites; the PBE-D2 method overestimates CO2 adsorption energies on multi-cation sites that are common in cationic zeolites with low Si/Al ratios. In contrast, a force field derived from the DFT/CC method performed well. Agreement was obtained between simulation and experiment not only for LTA-4A on which the force field fitting is based, but for other two common adsorbents, NaX and NaY.

  19. Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals.

    Science.gov (United States)

    Tu, Renyong; Xie, Yi; Bertoni, Giovanni; Lak, Aidin; Gaspari, Roberto; Rapallo, Arnaldo; Cavalli, Andrea; Trizio, Luca De; Manna, Liberato

    2016-06-01

    Cu2-xTe nanocubes were used as starting seeds to access metal telluride nanocrystals by cation exchanges at room temperature. The coordination number of the entering cations was found to play an important role in dictating the reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e., with coordination number 4), such as Cd(2+) or Hg(2+), yielded monocrystalline CdTe or HgTe nanocrystals with Cu2-xTe/CdTe or Cu2-xTe/HgTe Janus-like heterostructures as intermediates. The formation of Janus-like architectures was attributed to the high diffusion rate of the relatively small tetrahedrally coordinated cations, which could rapidly diffuse in the Cu2-xTe NCs and nucleate the CdTe (or HgTe) phase in a preferred region of the host structure. Also, with both Cd(2+) and Hg(2+) ions the exchange led to wurtzite CdTe and HgTe phases rather than the more stable zinc-blende ones, indicating that the anion framework of the starting Cu2-xTe particles could be more easily deformed to match the anion framework of the metastable wurtzite structures. As hexagonal HgTe had never been reported to date, this represents another case of metastable new phases that can only be accessed by cation exchange. On the other hand, the exchanges involving octahedrally coordinated ions (i.e., with coordination number 6), such as Pb(2+) or Sn(2+), yielded rock-salt polycrystalline PbTe or SnTe nanocrystals with Cu2-xTe@PbTe or Cu2-xTe@SnTe core@shell architectures at the early stages of the exchange process. In this case, the octahedrally coordinated ions are probably too large to diffuse easily through the Cu2-xTe structure: their limited diffusion rate restricts their initial reaction to the surface of the nanocrystals, where cation exchange is initiated unselectively, leading to core@shell architectures. Interestingly, these heterostructures were found to be metastable as they evolved to stable Janus-like architectures if annealed at 200 °C under vacuum.

  20. Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals

    CERN Document Server

    Tu, Renyong; Bertoni, Giovanni; Lak, Aidin; Gaspari, Roberto; Rapallo, Arnaldo; Cavalli, Andrea; De Trizio, Luca; Manna, Liberato

    2016-01-01

    Cu2-xTe nanocubes were used as starting seeds to access metal telluride nanocrystals by cation exchanges at room temperature. The coordination number of the entering cations was found to play an important role in dictating the reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e. with coordination number 4), such as Cd2+ or Hg2+, yielded monocrystalline CdTe or HgTe nanocrystals with Cu2-xTe/CdTe or Cu2-xTe/HgTe Janus-like heterostructures as intermediates. The formation of Janus-like architectures was attributed to the high diffusion rate of the relatively small tetrahedrally coordinated cations, which could rapidly diffuse in the Cu2-xTe NCs and nucleate the CdTe (or HgTe) phase in a preferred region of the host structure. Also, with both Cd2+ and Hg2+ ions the exchange led to wurtzite CdTe and HgTe phases rather than the more stable zinc-blende ones, indicating that the anion framework of the starting Cu2- xTe particles could be more easily deformed to match the anion framework of t...

  1. Effect of quinidine on cation exchange in cultured cells.

    Science.gov (United States)

    McCall, D

    1976-06-01

    The effects of quinidine on membrane ion exchange were examined using monolayer cultures of mammalian cells. Quinidine, in concentrations from 10(-6) to 10(-3) M, produced a prompt inhibition of the passive Na influx, dose-dependent along a sigmoid log dose-response curve. This effect was at a maximum for each concentration of the drug within 30 seconds of application. Passive Na influx (pmol/cm2/sec) decreased from 18.8 to 17.6 (P less than .05) and 10.5 (P less than .001) in the presence of 10(-6) and 10(-3) M quinidine, respectively. In the continued presence of quinidine, there was no further time-dependent effect on the Na influx, nor was there any tendency for the influx to recover. Washing the cells free of quinidine, however, resulted in a return of Na influx to control levels within 1 to 3 minutes. After 1 to 2 minute of quinidine treatment, coupled active Na efflux/K influx rapidly declined, reaching minimum values for each concentration between 2 to 4 minutes of drug treatment. Beyond that time, active Na/K fluxes again increased, but to values which remained significantly less than control, for up to 4 hours. Ten minutes of exposure to quinidine were required before any demonstrable effect on the passive K efflux could be recorded. In the presence of quinidine, there was reduced membrane turnover of both Na and K, but such that after a brief initial period (10 minutes or less) both ions were in flux equilibrium, explaining the absence of change in [Nai] and [Ki] in the presence of quinidine. Calculations of Ec1 indicated that, when present for 4 hours, quinidine did not change the Em in these cells although significant (P less than .001) reductions in apparent PNa and Pk values were recorded. The effect on PNa was much greater than that on Pk. The quinidine-induced flux changes occurred in a definite temporal sequence suggesting that they could all be explained on the basis of one direct initial action. This initial direct action, namely the prompt

  2. Strong cation-exchange chromatography of proteins on a sulfoalkylated monolithic cryogel.

    Science.gov (United States)

    Perçin, Işık; Khalaf, Rushd; Brand, Bastian; Morbidelli, Massimo; Gezici, Orhan

    2015-03-20

    A new strong cation exchanger (SCX) monolithic column was synthesized by at-line surface modification of a cryogel prepared by copolymerization of 2-hydroxyethylmethacrylate (HEMA) and glycidylmethacrylate (GMA). Sodium salt of 3-Mercaptopropane sulfonic acid (3-MPS) was used as the ligand to transform the surface of the monolith into a strong cation exchanger. The obtained material was characterized in terms of elemental analysis, infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) N2 adsorption, and used as a stationary phase for strong-cation exchange chromatography of some proteins, such as α-chymotrypsinogen, cytochrome c and lysozyme. Water permeability of the column was calculated according to Darcy's law (2.66×10(-13)m(2)). The performance of the monolithic cryogel column was evaluated on the basis of Height Equivalent to a Theoretical Plate (HETP). Retention behavior of the studied proteins was modeled on the basis of Yamamoto model to understand the role of the ion-exchange mechanism in retention behaviors. The considered proteins were successfully separated, and the obtained chromatogram was compared with that obtained with a non-functionalized cryogel column.

  3. Recent progress and applications of ion-exclusion/ion-exchange chromatography for simultaneous determination of inorganic anions and cations.

    Science.gov (United States)

    Nakatani, Nobutake; Kozaki, Daisuke; Mori, Masanobu; Tanaka, Kazuhiko

    2012-01-01

    One of the ultimate goals of ion chromatography is to determine both anions and cations found in samples with a single chromatographic run. In the present article, recent progress in ion-exclusion/ion-exchange chromatography for the simultaneous determinations of inorganic anions and cations are reviewed. Firstly, the principle and the control for the simultaneous separation and detection of analyte ions using ion-exclusion/cation-exchange chromatography with a weakly acidic cation-exchange column are outlined. Then, advanced chromatographic techniques in terms of analytical time, selectively and sensitivity are summarized. As a related method, ion-exclusion/anion-exchange chromatography with an anion-exchange column could be used for the simultaneous determination of inorganic nitrogen species, such as ammonium, nitrite and nitrate ions. Their usefulness and applications to water-quality monitoring and related techniques are also described.

  4. Study by XPS of different conditioning processes to improve the cation exchange in clinoptilolite

    Science.gov (United States)

    Ruiz-Serrano, D.; Flores-Acosta, M.; Conde-Barajas, E.; Ramírez-Rosales, D.; Yáñez-Limón, J. M.; Ramírez-Bon, R.

    2010-09-01

    We report the X-ray photoelectron spectroscopy (XPS) analysis of natural clinoptilolite from a mine in Sonora, México. From these measurements we determined the chemical state and binding energy of the elements in the zeolite framework and of those in the extra framework sites. The analysis was done on natural clinoptilolite and on cation-exchanged clinoptilolites with Na + and NH4+ ions. Complementary analysis by several experimental techniques was performed to determine the structural, chemical composition and chemical state modifications experimented by clinoptilolite samples processed by the two types of cation exchange. The clinoptilolite samples were studied by X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) to determine their structural composition, Energy Dispersive Spectroscopy (EDS) to measure the chemical composition and electronic paramagnetic resonance (EPR) spectroscopy to determine the chemical state of iron inside the natural zeolites.

  5. Multicolour synthesis in lanthanide-doped nanocrystals through cation exchange in water

    KAUST Repository

    Han, Sanyang

    2016-10-04

    Meeting the high demand for lanthanide-doped luminescent nanocrystals across a broad range of fields hinges upon the development of a robust synthetic protocol that provides rapid, just-in-time nanocrystal preparation. However, to date, almost all lanthanide-doped luminescent nanomaterials have relied on direct synthesis requiring stringent controls over crystal nucleation and growth at elevated temperatures. Here we demonstrate the use of a cation exchange strategy for expeditiously accessing large classes of such nanocrystals. By combining the process of cation exchange with energy migration, the luminescence properties of the nanocrystals can be easily tuned while preserving the size, morphology and crystal phase of the initial nanocrystal template. This post-synthesis strategy enables us to achieve upconversion luminescence in Ce3+ and Mn2+-activated hexagonal-phased nanocrystals, opening a gateway towards applications ranging from chemical sensing to anti-counterfeiting.

  6. Effect of Simulated N Deposition on Soil Exchangeable Cations in Three Forest Types of Subtropical China

    Institute of Scientific and Technical Information of China (English)

    LU Xian-Kai; MO Jiang-Ming; P.GUNDERSERN; ZHU Wei-Xing; ZHOU Guo-Yi; LI De-Jun; ZHANG Xu

    2009-01-01

    The effects of simulated nitrogen (N) deposition on soil exchangeable cations were studied in three forest types of subtropical China.Four N treatments with three replications were designed for the monsoon evergreen broadleaf forest (mature forest):control (0 kg N ha-1 year-1),low N (50 kg N ha-1 year-1),medium N (100 kg N ha-1 year-1) and high N (150 kg N ha-1 ycar-1),and only three treatments (i.e.,control,low N,medium N) were established for the pine and mixed forests.Nitrogen had been applied continuously for 26 months before the measurement.The mature forest responded more rapidly and intensively to N additions than the pine and mixed forests,and exhibited some significant negative symptoms,e.g.,soil acidification,Al mobilization and leaching of base cations from soil.The pine and mixed forests responded slowly to N additions and exhibited no significant response of soil cations.Response of soil exchangeable cations to N deposition varied in the forests of subtropical China,depending on soil N status and land-nse history.

  7. Influence of the type of exchangeable cation on the electrolytic conductivity of bentonite suspensions

    Directory of Open Access Journals (Sweden)

    Daković Aleksandra S.

    2003-01-01

    Full Text Available The electrolytic conductivity of bentonite aqueous suspensions was investigated. The starting material (Ca-Mont was exchanged with sodium ions, using an ion exchange column. The sodium form of bentonite (Na-Mont was used to obtain organobentonites. The electrolytic conductivity of the starting material, Na-Mont and organobentonites was studied for different suspension concentration. The highest value of the electrolytic conductivity was obtained for Na-Mont, while the organic cation in the bentonite structure decreased the electrolytic conductivity.

  8. Solubility and cation exchange in phosphate rock and saturated clinoptilolite mixtures

    Science.gov (United States)

    Allen, E. R.; Hossner, L. R.; Ming, D. W.; Henninger, D. L.

    1993-01-01

    Mixtures of zeolite and phosphate rock (PR) have the potential to provide slow-release fertilization of plants in synthetic soils by dissolution and ion-exchange reactions. This study was conducted to examine solubility and cation-exchange relationships in mixtures of PR and NH4- and K-saturated clinoptilolite (Cp). Batch-equilibration experiments were designed to investigate the effect of PR source, the proportion of exchangeable K and NH4, and the Cp to PR ratio on solution N, P, K, and Ca concentrations. The dissolution and cation-exchange reactions that occurred after mixing NH4- and K-saturated Cp with PR increased the solubility of the PR and simultaneously released NH4 and K into solution. The more reactive North Carolina (NC) PR rendered higher solution concentrations of NH4 and K when mixed with Cp than did Tennessee (TN) PR. Solution P concentrations for the Cp-NC PR mixture and the Cp-TN PR mixture were similar. Solution concentrations of N, P, K, and Ca and the ratios of these nutrients in solution varied predictably with the type of PR, the Cp/PR ratio, and the proportions of exchangeable K and NH4 on the Cp. Our research indicated that slow-release fertilization using Cp/PR media may provide adequate levels of N, P, and K to support plant growth. Solution Ca concentrations were lower than optimum for plant growth.

  9. Cation Exchange Resins and colonic perforation. What surgeons need to know

    OpenAIRE

    María Rita Rodríguez-Luna; Enrique Fernández-Rivera; Joaquín E. Guarneros-Zárate; Jorge Tueme-Izaguirre; José Roberto Hernández-Méndez

    2015-01-01

    Introduction: Since 1961 the use of Cation Exchange Resins has been the mainstream treatment for chronic hyperkalemia. For the past 25 years different kind of complications derived from its clinical use have been recognized, being the colonic necrosis the most feared and lethal of all. Presentation of case: We report a case of a 72-year-old patient with chronic kidney disease, treated with calcium polystyrene sulfonate for hyperkalemia treatment who presented in the emergency department wi...

  10. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange

    KAUST Repository

    Binetti, Enrico

    2015-10-27

    Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red and near-infrared spectral regions, are of great interest for optoelectronic and bio-imaging applications. The growth of an inorganic passivation layer on nanocrystal surfaces is a common strategy to improve their chemical and optical stability and their photoluminescence quantum yield. In particular, cation exchange is a suitable approach for shell growth at the expense of the nanocrystal core size. Here, the cation exchange process is used to promote the formation of a CdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blue shifting their optical spectra and yielding luminescent and stable nanostructures emitting in the range of 700–850 nm. Structural, morphological and compositional investigation confirms the nanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystalline phase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of a passivation layer with a decrease of the PbS core size, as inferred by the blue-shift of the excitonic peaks. The surface passivation strongly increases the photoluminescence intensity and the excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidation over time. Thanks to their absorption and emission spectral range and the slow recombination dynamics, such highly luminescent nano-objects can find interesting applications in sensitized photovoltaic cells and light-emitting devices.

  11. Insights into cation exchange selectivity of a natural clinoptilolite by means of dielectric relaxation spectroscopy

    Science.gov (United States)

    Rodríguez-Fuentes, Gerardo; Devautour-Vinot, Sabine; Diaby, Sekou; Henn, François

    2011-09-01

    Purified natural clinoptilolite from the Tasajeras deposit, Cuba, and some of its metal exchanged forms are studied, at the dehydrated state, by means of dielectric relaxation spectroscopy (DRS) using two different modus operandi: complex impedance spectroscopy and dielectric dynamic thermal analysis. Data analysis yields the determination of the extra-framework cation (EFC) population into the various possible crystallographic sites of the zeolitic framework as well as of the activation energy characterizing the localized hopping mechanism of EFC. First, it is shown that the DRS responses obtained here match well with the previous reported data, which were previously localized EFCs in positions close to M1 and M2 sites when the clinoptilolite is modified to almost homoionic form. From this outcome, it can be concluded that all EFCs are in the same crystallographic situation regarding solvation or, in other terms, that no steric effect can be taken into account to explain cationic selectivity. Second, based on the assumption that the activation energy for EFC hopping is directly connected to the EFC/framework interaction and on simple thermodynamics consideration, we show this interaction does not govern the EFC exchange reaction. So, it is emphasized that EFC/H2O interaction is the key factor for cation exchange selectivity.

  12. Cation exchange on the nanoscale: an emerging technique for new material synthesis, device fabrication, and chemical sensing.

    Science.gov (United States)

    Rivest, Jessy B; Jain, Prashant K

    2013-01-01

    Cation exchange is an age-old technique for the chemical conversion of liquids or extended solids by place-exchanging the cations in an ionic material with a different set of cations. The technique is undergoing a major revival with the advent of high-quality nanocrystals: researchers are now able to overcome the limitations in bulk systems and fully exploit cation exchange for materials synthesis and discovery via rapid, low-temperature transformations in the solid state. In this tutorial review, we discuss cation exchange as a promising materials synthesis and discovery tool. Exchange on the nanoscale exhibits some unique attributes: rapid kinetics at room temperature (orders of magnitude faster than in the bulk) and the tuning of reactivity via control of nanocrystal size, shape, and surface faceting. These features make cation exchange a convenient tool for accessing nanocrystal compositions and morphologies for which conventional synthesis may not be established. A simple exchange reaction allows extension of nanochemistry to a larger part of the periodic table, beyond the typical gamut of II-VI, IV-VI, and III-V materials. Cation exchange transformations in nanocrystals can be topotactic and size- and shape-conserving, allowing nanocrystals synthesized by conventional methods to be used as templates for production of compositionally novel, multicomponent, or doped nanocrystals. Since phases and compositions resulting from an exchange reaction can be kinetically controlled, rather than governed by the phase diagram, nanocrystals of metastable and hitherto inaccessible compositions are attainable. Outside of materials synthesis, applications for cation exchange exist in water purification, chemical staining, and sensing. Since nanoscale cation exchange occurs rapidly at room temperature, it can be integrated with sensitive environments such as those in biological systems. Cation exchange is already allowing access to a variety of new materials and processes

  13. Anion and cation mixed-bed ion exchange for enhanced multidimensional separations of peptides and phosphopeptides.

    Science.gov (United States)

    Motoyama, Akira; Xu, Tao; Ruse, Cristian I; Wohlschlegel, James A; Yates, John R

    2007-05-15

    Shotgun proteomics typically uses multidimensional LC/MS/MS analysis of enzymatically digested proteins, where strong cation-exchange (SCX) and reversed-phase (RP) separations are coupled to increase the separation power and dynamic range of analysis. Here we report an on-line multidimensional LC method using an anion- and cation-exchange mixed bed for the first separation dimension. The mixed-bed ion-exchange resin improved peptide recovery over SCX resins alone and showed better orthogonality to RP separations in two-dimensional separations. The Donnan effect, which was enhanced by the introduction of fixed opposite charges in one column, is proposed as the mechanism responsible for improved peptide recovery by producing higher fluxes of salt cations and lower populations of salt anions proximal to the SCX phase. An increase in orthogonality was achieved by a combination of increased retention for acidic peptides and moderately reduced retention of neutral to basic peptides by the added anion-exchange resin. The combination of these effects led to approximately 100% increase in the number of identified peptides from an analysis of a tryptic digest of a yeast whole cell lysate. The application of the method to phosphopeptide-enriched samples increased by 94% phosphopeptide identifications over SCX alone. The lower pKa of phosphopeptides led to specific enrichment in a single salt step resolving acidic phosphopeptides from other phospho- and non-phosphopeptides. Unlike previous methods that use anion exchange to alter selectivity or enrich phosphopeptides, the proposed format is unique in that it works with typical acidic buffer systems used in electrospray ionization, making it feasible for online multidimensional LC/MS/MS applications.

  14. Changes of Soil Water, Organic Matter, and Exchangeable Cations Along a Forest Successional Gradient in Southern China

    Institute of Scientific and Technical Information of China (English)

    YAN Jun-Hua; ZHOU Guo-Yi; ZHANG De-Qiang; CHU Guo-Wei

    2007-01-01

    Information on the distribution patterns of soil water content (SWC), soil organic matter (SOM), and soil exchangeable cations (SEC) is important for managing forest ecosystems in a sustainable manner. This study investigated how SWC, SOM, and SEC were influenced in forests along a successional gradient, including a regional climax (monsoon evergreen broad-leaved forest, or MEBF), a transitional forest (coniferous and broad-leaved mixed forest, or MF), and a pioneer forest (coniferous Masson pine (Pinus massoniana) forest, or MPF) of the Dinghushan Biosphere Reserve in the subtropical region of southern China. SWC, SOM, and SEC excluding Ca2+ were found to increase in the soil during forest succession, being highest in the top soil layer (0 to 15 cm depth) except for Na+. The differences between soil layers were largest in MF. This finding also suggested that the nutrients were enriched in the topsoil when they became increasingly scarce in the soil. There were no significant differences (P = 0.05) among SWC, SOM, and SBC. A linear, positive correlation was found between SWC and SOM. The correlation between SOM and cation exchange capacity (CEC) was statistically significant, which agreed with the theory that the most important factor determining SEC is SOM. The ratio of K+ to Na+ in the topsoil was about a half of that in the plants of each forest. MF had the lowest exchangeable Ca2+ concentration among the three forests and Ca2+:K+ in MPF was two times higher than that in MF. Understanding the changes of SWC, SOM, and CEC during forest succession would be of great help in protecting all three forests in southern China.

  15. Analyzing freely dissolved concentrations of cationic surfactant utilizing ion-exchange capability of polyacrylate coated solid-phase microextraction fibers

    NARCIS (Netherlands)

    Chen, Y.; Droge, S.T.J.; Hermens, J.L.M.

    2012-01-01

    A 7-μm polyacrylate (PA) coated fiber was successfully employed to determine freely dissolved concentrations of cationic surfactants by solid-phase microextraction (SPME) and utilizing the capability of the PA-coating to sorb organic cations via ion-exchange at carboxylic groups. Measured fiber-wate

  16. Synthesis of silver embedded poly(o-anisidine molybdophosphate nano hybrid cation-exchanger applicable for membrane electrode.

    Directory of Open Access Journals (Sweden)

    Anish Khan

    Full Text Available Poly(o-anisidine molybdophosphate was expediently obtained by sol-gel mixing of Poly(o-anisidine into the inorganic matrices of molybdophosphate, which was allowed to react with silver nitrate to the formation of poly(o-anisidine molybdophosphate embedded silver nano composite. The composite was characterized by Fourier Transform Infrared Spectroscopy, X-ray powder diffraction, UV-Vis Spectrophotometry, Fluorescence Spectroscopy, Scanning Electron Microscopy/Energy-dispersive X-ray Spectroscopy and Thermogravimertic Analysis. Ion exchange capacity and distribution studies were carried out to understand the ion-exchange capabilities of the nano composite. On the basis of highest distribution studies, this nano composite cation exchanger was used as preparation of heavy metal ion selective membrane. Membrane was characterized for its performance as porosity and swelling later on was used for the preparation of membrane electrode for Hg(II, having better linear range, wide working pH range (2-4.5 with fast response in the real environment.

  17. Preparation of a Cation Exchanger from Cork Waste: Thermodynamic Study of the Ion Exchange Processes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An ion exchanger was prepared by sulfonation of cork-waste chars. The exchange properties of the resultant materialwere characterized using Na+, Ca2+ or Fe3+ aqueous solutions, The content of metal ions in the solutions weredetermined by atomic absorption spectrometry. On the basis of the results obtained, the chemical equilibrium andits thermodynamic aspects related to the ion exchange process were studied. It was found that equilibrium constantK varies by the order: Na+<Ca2+<Fe3+, its value increasing with increasing temperature, and that △H°>0 and△S°>0, with -△G° following the sequence: Ca2+>Na+>Fe3+,

  18. Chabazite: stable cation-exchanger in hyper alkaline concrete pore water.

    Science.gov (United States)

    Van Tendeloo, Leen; Wangermez, Wauter; Kurttepeli, Mert; de Blochouse, Benny; Bals, Sara; Van Tendeloo, Gustaaf; Martens, Johan A; Maes, André; Kirschhock, Christine E A; Breynaert, Eric

    2015-02-17

    To avoid impact on the environment, facilities for permanent disposal of hazardous waste adopt multibarrier design schemes. As the primary barrier very often consists of cement-based materials, two distinct aspects are essential for the selection of suitable complementary barriers: (1) selective sorption of the contaminants in the repository and (2) long-term chemical stability in hyperalkaline concrete-derived media. A multidisciplinary approach combining experimental strategies from environmental chemistry and materials science is therefore essential to provide a reliable assessment of potential candidate materials. Chabazite is typically synthesized in 1 M KOH solutions but also crystallizes in simulated young cement pore water, a pH 13 aqueous solution mainly containing K(+) and Na(+) cations. Its formation and stability in this medium was evaluated as a function of temperature (60 and 85 °C) over a timeframe of more than 2 years and was also asessed from a mechanistic point of view. Chabazite demonstrates excellent cation-exchange properties in simulated young cement pore water. Comparison of its Cs(+) cation exchange properties at pH 8 and pH 13 unexpectedly demonstrated an increase of the KD with increasing pH. The combined results identify chabazite as a valid candidate for inclusion in engineered barriers for concrete-based waste disposal.

  19. A comparative study of chelating and cationic ion exchange resins for the removal of palladium(II) complexes from acidic chloride media.

    Science.gov (United States)

    Hubicki, Zbigniew; Wołowicz, Anna

    2009-05-30

    The increasing demand for palladium for technological application requires the development of ion exchange chromatography. Recently ion exchange chromatography has developed largely as a result of new types of ion exchangers available on the market of which two types are widely applied. One of them are selective (chelating) and modified ion exchangers and the other one are liquid exchangers. Two types of ion exchange resins such as chelating (Lewatit TP 214, Purolite S 920) and cationic (Chelite S, Duolite GT 73) ion exchangers are used for the recovery of palladium(II) complexes from chloride media (0.1-2.0M HCl-1.0M NaCl-0.0011 M Pd(II); 0.1-2.0M HCl-2.0M NaCl-0.0011M Pd(II)). The influence of concentration of hydrochloric acid, sodium chloride as well as the phase contact time on the degree of recovery of palladium(II) complexes was studied. Moreover, the amount of palladium(II) chlorocomplexes sorbed onto ion exchangers, the working ion exchange capacities and the weight and bed distribution coefficients were calculated in order to judge which of two types of resins possesses the best performance towards palladium(II) complexes.

  20. High-speed ion-exclusion chromatography of dissolved carbon dioxide on a small weakly acidic cation-exchange resin column with ion-exchange enhancement columns of conductivity detection.

    Science.gov (United States)

    Mori, Masanobu; Ikedo, Mikaru; Hu, Wenzhi; Helaleh, Murad I H; Xu, Qun; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2005-10-28

    The high-speed ion-exclusion chromatographic determination of dissolved carbon dioxide, i.e., carbonic acid, hydrogencarbonate or carbonate, with conductivity detection was obtained using a small column packed with a weakly acidic cation-exchange resin in the H+-form (40 mm long x 4.6 mm i.d., 3 microm-particle and 0.1 meq./ml-capacity). Two different ion-exchange resin columns, which were a strongly acidic cation-exchange resin in the K+-form and a strongly basic anion-exchange resin in the OH- -form, were connected after the separation column. The sequence of columns could convert dissolved carbon dioxide to KOH having high conductivity response. The enhancement effect for dissolved carbon dioxide could retain even on the vast chromatographic runs, by using the enhancement columns with high ion-exchange capacity above 1.0 meq./ml. The retention time was in 60 s at flow-rate of 1.2 ml/min. The calibration graph of dissolved carbon dioxide estimated as H2CO3- was linear in the range of 0.005-10 mM. The detection limit at signal to noise of 3 was 0.15 microM as H2CO3-. This method was applicable to several rainwater and tap water samples.

  1. Determination of organoarsenic species in marine samples using gradient elution cation exchange HPLC-ICP-MS

    DEFF Research Database (Denmark)

    Sloth, Jens Jørgen; Larsen, Erik Huusfeldt; Julshamn, Kåre

    2003-01-01

    A method for the determination of arsenic species in marine samples using high performance liquid chromatography coupled to inductively coupled mass spectrometry (HPLC-ICP-MS) has been developed. Cation exchange HPLC with gradient elution using pyridine formate as the mobile phase was employed...... the certified limits and low detection limits of 0.002-0.005 mug g(-1) dry mass (as As) for the different arsenic species were obtained. At least 23 different organic arsenic species were detected in a scallop kidney in one analytical run of 25 min duration. The ability of our analytical method to detect...

  2. Refolding of Denatured/Reduced Lysozyme Using Weak-Cation Exchange Chromatography

    Institute of Scientific and Technical Information of China (English)

    Yan WANG; Bo Lin GONG; Xin Du GENG

    2003-01-01

    Oxidative refolding of the denatured/reduced lysozyme was investigated by using weak-cation exchange chromatography (WCX). The stationary phase of WCX binds to the reduced lysozyme and prevented it from forming intermolecular aggregates. At the same time urea and ammonium sulfate were added to the mobile phase to increase the elution strength for lysozyme. Ammonium sulfate can more stabilize the native protein than a common eluting agent, sodium chloride. Refolding of lysozyme by using this WCX is successfully. It was simply carried out to obtain a completely and correctly refolding of the denatured lysozyme at high concentration of 20.0 mg/mL.

  3. PREPARATION OF SA-Fe CATION EXCHANGE MEMBRANE AND IT'S APPLICATION IN ELECTRODIALYSIS FOR TREATING WASTEWATER

    Institute of Scientific and Technical Information of China (English)

    GENG Yamin; CHEN Zhen; ZHENG Xi; HUANG Xuehong; CHEN Riyao

    2006-01-01

    An insoluble SA-Fe membrane was prepared by being linked soluble sodium alginate with FeCl3. SEM was used to observe its surface structure. IR spectrum indicated that Fe3+ was linked with -COOH and -OH in SA membrane. As a cationic exchanging membrane in electrodialysis the membrane was applied in treating inorganic wastewater with high concentration of inorganic ammonia and azote. The results of experiment showed that it was well-selective to ammonia and azote. The percentage of the removal of ammonia and azote in wastewater was up to 80%.

  4. Strong cation exchange chromatography in analysis of posttranslational modifications: innovations and perspectives.

    Science.gov (United States)

    Edelmann, Mariola J

    2011-01-01

    Strong cation exchange (SCX) chromatography has been utilized as an excellent separation technique that can be combined with reversed-phase (RP) chromatography, which is frequently used in peptide mass spectrometry. Although SCX is valuable as the second component of such two-dimensional separation methods, its application goes far beyond efficient fractionation of complex peptide mixtures. Here I describe how SCX facilitates mapping of the protein posttranslational modifications (PTMs), specifically phosphorylation and N-terminal acetylation. The SCX chromatography has been mainly used for enrichment of these two PTMs, but it might also be beneficial for high-throughput analysis of other modifications that alter the net charge of a peptide.

  5. Modified DIX model for ion-exchange equilibrium of L-phenylalanine on a strong cation-exchange resin☆

    Institute of Scientific and Technical Information of China (English)

    Jinglan Wu; Pengfei Jiao; Wei Zhuang; Jingwei Zhou; Hanjie Ying

    2016-01-01

    L-phenylalanine, one of the nine essential amino acids for the human body, is extensively used as an ingredient in food, pharmaceutical and nutrition industries. A suitable equilibrium model is required for purification of L-phenylalanine based on ion-exchange chromatography. In this work, the equilibrium uptake of L-phenylalanine on a strong acid-cation exchanger SH11 was investigated experimental y and theoretical y. A modified Donnan ion-exchange (DIX) model, which takes the activity into account, was established to predict the uptake of L-phenyl-alanine at various solution pH values. The model parameters including selectivity and mean activity coefficient in the resin phase are presented. The modified DIX model is in good agreement with the experimental data. The optimum operating pH value of 2.0, with the highest L-phenylalanine uptake on the resin, is predicted by the model. This basic information combined with the general mass transfer model wil lay the foundation for the prediction of dynamic behavior of fixed bed separation process.

  6. Preparation of Weak Cation Exchange Packings Based on Monodisperse Poly (chloromethylstyrene-co-divinylbenzene) Particles and Its Chromatographic Properties

    Institute of Scientific and Technical Information of China (English)

    卫引茂; 陈强; 耿信笃

    2001-01-01

    Monodisperse poly ( chloromethylstyrene-co-divinylbenzene )particles were firstly prepared by a two-step swelling method.Based on this media, one kind of weak cation ion exchange packings was prepared. It was demonstrated that the prepared packings have comparative advantages for biopolymer separation with high column efficiency, low interstitial volume and low column backpressure, and have good resolution to proteins. The effects of salt concentration and pH of mobile phase on protein retentions were investigated. The properties of the weak cation ion exchange packings were evaluated by the unified retention model for mixed-mode interaction mechanison in ion exchange and hydrophobic interaction chromatography.

  7. Model Simulations of a Field Experiment on Cation Exchange-affected Multicomponent Solute Transport in a Sandy Aquifer

    DEFF Research Database (Denmark)

    Bjerg, Poul Løgstrup; Ammentorp, Hans Christian; Christensen, Thomas Højlund

    1993-01-01

    A large-scale and long-term field experiment on cation exchange in a sandy aquifer has been modelled by a three-dimensional geochemical transport model. The geochemical model includes cation-exchange processes using a Gaines-Thomas expression, the closed carbonate system and the effects of ionic...... of 800 days due to a substantially attenuation in the aquifer. The observed and the predicted breakthrough curves showed a reasonable accordance taking the duration of the experiment into account. However, some discrepancies were observed probably caused by the revealed non-ideal exchange behaviour of K+....

  8. Measurement of (90)Sr in environmental samples by cation-exchange and liquid scintillation counting.

    Science.gov (United States)

    Amano, H; Yanase, N

    1990-06-01

    A new method for the measurement of (90)Sr in environmental samples by cation-exchange and liquid scintillation counting is described. Strontium carbonate is purified by precipitation and ion-exchange, weighed for the determination of chemical yield, dissolved in hydrochloric acid and mixed with the liquid scintillator, Aquasol-2. Two channels of a low-background liquid scintillation counter are used to determine (90)Sr, (90)Y and (89)Sr, free from the effects of environmental tritium. The values of (90)Sr obtained by this method are in good agreement with those from ordinary (90)Y milking and the gas proportional counting method. The concentration of (90)Sr in the air at Tokai-mura in Japan has been measured by the new method.

  9. Kinetics of Isovalent (Cd(2+)) and Aliovalent (In(3+)) Cation Exchange in Cd1-xMnxSe Nanocrystals.

    Science.gov (United States)

    Chakraborty, Pradip; Jin, Yu; Barrows, Charles J; Dunham, Scott T; Gamelin, Daniel R

    2016-10-05

    Ion exchange, in which an in-diffusing ion replaces a lattice ion, has been widely exploited as a synthetic tool for semiconductor doping and solid-to-solid chemical transformations, both in bulk and at the nanoscale. Here, we present a systematic investigation of cation-exchange reactions that involve the displacement of Mn(2+) from CdSe nanocrystals by Cd(2+) or In(3+). For both incoming cations, Mn(2+) displacement is spontaneous but thermally activated, following Arrhenius behavior over a broad experimental temperature range. At any given temperature, cation exchange by In(3+) is approximately 2 orders of magnitude faster than that by Cd(2+), illustrating a critical dependence on the incoming cation. Quantitative analysis of the kinetics data within a Fick's-law diffusion model yields diffusion barriers (ED) and limiting diffusivities (D0) for both incoming ions. Despite their very different kinetics, indistinguishable diffusion barriers of ED ≈ 1.1 eV are found for both reactions (In(3+) and Cd(2+)). A dramatically enhanced diffusivity is found for Mn(2+) cation exchange by In(3+). Overall, these findings provide unique experimental insights into cation diffusion within colloidal semiconductor nanocrystals, contributing to our fundamental understanding of this rich and important area of nanoscience.

  10. On-line cation-exchange preconcentration and capillary electrophoresis coupled by tee joint interface.

    Science.gov (United States)

    Zhang, Zhao-Xiang; He, You-Zhao

    2005-02-25

    An on-line preconcentration method based on ion exchange solid phase extraction was developed for the determination of cationic analytes in capillary electrophoresis (CE). The preconcentration-separation system consisted of a preconcentration capillary bonded with carboxyl cation-exchange stationary phase, a separation capillary for zone electrophoresis and a tee joint interface of the capillaries. Two capillaries were connected closely inside a 0.3 mm i.d. polytetrafluoroethylene tube with a side opening and fixed together by the interface. The preparations of the preconcentration capillaries and interface were described in detail in this paper. The on-line preconcentration and separation procedure of the analysis system included washing and conditioning the capillaries, loading analytes, filling with buffer solution, eluting analytes and separating by capillary zone electrophoresis (CZE). Several analysis parameters, including sample loading flow rate and time, eluting solution and volume, inner diameter and length of preconcentration capillary etc., were investigated. The proposed method enhanced the detection sensitivity of CE-UV about 5000 times for propranolol and metoprolol compared with normally electrokinetic injection. The detection limits of propranolol and metoprolol were 0.02 and 0.1 microg/L with the proposed method respectively, whereas those were 0.1 and 0.5 mg/L with conventional electrokinetic injection. The experiment results demonstrate that the proposed technique can increase the preconcentration factor evidently.

  11. Morphologically Aligned Cation-Exchange Membranes by a Pulsed Electric Field for Reverse Electrodialysis.

    Science.gov (United States)

    Lee, Ju-Young; Kim, Jae-Hun; Lee, Ju-Hyuk; Kim, Seok; Moon, Seung-Hyeon

    2015-07-21

    A low-resistance ion-exchange membrane is essential to achieve the high-performance energy conversion or storage systems. The formation methods for low-resistance membranes are various; one of the methods is the ion channel alignment of an ion-exchange membrane under a direct current (DC) electric field. In this study, we suggest a more effective alignment method than the process with the DC electric field. First, an ion-exchange membrane was prepared under a pulsed electric field [alternating current (AC) mode] to enhance the effectiveness of the alignment. The membrane properties and the performance in reverse electrodialysis (RED) were then examined to assess the membrane resistance and ion selectivity. The results show that the membrane electrical resistance (MER) had a lower value of 0.86 Ω cm(2) for the AC membrane than 2.13 Ω cm(2) observed for the DC membrane and 4.30 Ω cm(2) observed for the pristine membrane. Furthermore, RED achieved 1.34 W/m(2) of maximum power density for the AC membrane, whereas that for the DC membrane was found to be 1.14 W/m(2) [a RED stack assembled with CMX, used as a commercial cation-exchange membrane (CEM), showed 1.07 W/m(2)]. Thereby, the novel preparation process for a remarkable low-resistance membrane with high ion selectivity was demonstrated.

  12. Solubility and Cation Exchange Properties of Synthetic Hydroxyapatite and Clinoptilolite Mixtures

    Science.gov (United States)

    Beiersdorfer, Raymond E.; Ming, Douglas W.

    2003-01-01

    A zeoponic plant growth system is defined as the cultivation of plants in artificial soils, which have zeolites as a major component. These systems: 1) can serve as a controllable and renewable fertilization system to provide plant growth nutrients; 2) can mitigate the adverse effects of contamination due to leaching of highly soluble and concentrated fertilizers; and 3) are being considered as substrates for plant growth in regenerative life-support systems for long-duration space missions. Batch-equilibrium studies of the dissolution and ion-exchange properties of mixtures of naturally-occurring Wyoming clinoptilolite (a zeolite) exchanged with K(+) or NH4(+); and synthetic hydroxyapatite were conducted to determine: 1) the plant availability of the macro-nutrients NH4-N, P, K, Ca, and Mg and 2) the effects of varying the clinoptilolite to hydroxyapatite ratio and the ratio of exchangeable cations (K(+) vs. NH4(+)) on clinoptilolite extraframework sites. The nutrients NH4-N (19.7 to 73.6 mg L(sup -1), P (0.57 to 14.99 mg L(sup- 1), K (14.8 to 104.9 mg L(sup -1), and Mg (0.11 to 6.68mg L(sup -1) are available to plants at sufficient levels. Solution Ca concentrations (0.47 to 3.40 mg L(sup -1) are less than optimal. Solution concentrations of NH4(+), K(+), Ca(2+), and Mg(2+) all decreased with increasing clinoptilolite to hydroxyapatite ratio in the sample. Solution concentrations of phosphorous initially increased, reached a maximum value and then decreased with increasing clinoptilolite to hydroxyapatite ratio in the sample. The NH4(+) -exchanged clinoptilolite is more efficient in dissolving synthetic hydroxyapatite than the K(+) -exchanged clinoptilolite. This suggests that NH4(+), which is less selective at clinoptilolite extraframework sites than K(+) is exchanged more readily by Ca(2+) and thereby enhances the dissolution of the synthetic hydroxyapatite.

  13. Pomegranate (Punica granatum) juices: chemical composition, micronutrient cations, and antioxidant capacity.

    Science.gov (United States)

    El Kar, Chiraz; Ferchichi, Ali; Attia, Faouzi; Bouajila, Jalloul

    2011-08-01

    Phenolics, flavonoids, anthocyanins, and tannins of pomegranate juices, obtained from 9 Tunisian ecotypes were quantified. Phenolics and flavonoids in the variety Tounsi (TN) (3299 mg gallic acid equivalents [GAE]/L and 636 mg quercetin equivalents [QE]/L of juice, respectively) were higher than in the variety Gabsi (GB) (1570 mg GAE/L and 135 mg QE/L of juice, respectively). The highest anthocyanins quantity was found in GB 2 with 156 mg cyanidin-3-glucoside equivalents (CGE)/L. TN 3 ecotype showed the highest tannins quantity with 2550 mg catechin equivalents (CE)/L of juice. TN 1 presented the highest radical-scavenging activity (2, 2'-azinobis-3-ethylbenzothiazoline-6-sulphonate [ABTS], IC₅₀ [50% inhibition concentration] = 525 mg/L), as well as the highest concentration of micronutrient cations (potassium and sodium). A high correlation (R² = 0.80) between antioxidant capacity and proanthocyanin contents was found, this suggests that proanthocyanins are the principal contributor in the antioxidant capacity of pomegranate. Our data suggest also that the high concentrations of K⁺ and Na⁺ may play a role in the adaptation of pomegranate to arid environments.

  14. Cu2Se and Cu Nanocrystals as Local Sources of Copper in Thermally Activated In Situ Cation Exchange

    KAUST Repository

    Casu, Alberto

    2016-01-27

    Among the different synthesis approaches to colloidal nanocrystals a recently developed toolkit is represented by cation exchange reactions, where the use of template nanocrystals gives access to materials that would be hardly attainable via direct synthesis. Besides, post-synthetic treatments, such as thermally activated solid state reactions, represent a further flourishing route to promote finely controlled cation exchange. Here, we report that, upon in situ heating in a transmission electron microscope, Cu2Se nanocrystals deposited on an amorphous solid substrate undergo partial loss of Cu atoms, which are then engaged in local cation exchange reactions with Cu “acceptors” phases represented by rod- and wire- shaped CdSe nanocrystals. This thermal treatment slowly transforms the initial CdSe nanocrystals into Cu2-xSe nanocrystals, through the complete sublimation of Cd and the partial sublimation of Se atoms. Both Cu “donor” and “acceptor” particles were not always in direct contact with each other, hence the gradual transfer of Cu species from Cu2Se or metallic Cu to CdSe nanocrystals was mediated by the substrate and depended on the distance between the donor and acceptor nanostructures. Differently from what happens in the comparably faster cation exchange reactions performed in liquid solution, this study shows that slow cation exchange reactions can be performed at the solid state, and helps to shed light on the intermediate steps involved in such reactions.

  15. Preparation and Cation Exchange Properties of Zeolitic Adsorbents Using Fused Coal Fly Ash and Seawater

    Science.gov (United States)

    Hirai, Takashi; Wajima, Takaaki; Yoshizuka, Kazuharu

    For the development of functional material using coal fly ash discharged from thermal power plants, we have prepared zeolitic adsorbents derived from alkaline fused coal fly ash in several aqueous saline media to obtain the optimized preparation condition. The NH4+ exchange capacity of the product prepared at 80°C for 12 hours in diluted seawater using the precursor fused at 500°C was 4.6 mmol⁄g which is equivalent that of product prepared in deionized water. Zeolite-X and zeolite-A were produced in all aqueous media, in addition hydroxysodalite was produced over 12 hours. It was suggested that zeolite-A transform into hydroxysodalite in the products. The zeolitic adsorbents having high ion exchange capacity could be prepared in twice diluted seawater at 6-12 hours in 80°C using a precursor fused at 500°C.

  16. Effects of exchangeable cation composition on the thermal expansion/contraction of clinoptilolite

    Energy Technology Data Exchange (ETDEWEB)

    Bish, D.L.

    1984-12-31

    To understand and predict the effects of a thermal pulse induced by a radioactive waste repository on clinoptilolite-bearing rocks, the lattice parameters of 6 natural and 3 cation-exchanged (Ca, K, Na) clinoptilolites were studied as a function of temperature. The samples were examined at room temperature, under vacuum, and at 50{sup 0}C increments to 300{sup 0}C using a high-temperature x-ray powder diffractometer. The unit cell of all samples decreased in volume between 20 and 300{sup 0}C; Na-saturated clinoptilolite underwent the greatest volume decrease (8.4%) and K-saturated clinoptilolite the smallest (1.6%), of the clinoptilolites studied. The volume decrease for the Ca-saturated clinoptilolite was 3.6%. The highest percentage decrease for each sample was along the b axis, generally 80 to 90% of the total volume decrease. The change in the a axis was the smallest and was usually <5%, although 26.5% of the contraction of the Na-exchanged clinoptilolite was along a. The bulk of the volume contraction of many samples occurred on evacuation at room temperature, demonstrating that the observed changes were due to water loss and not to temperature-induced structural changes. Low-angle scattering was significantly reduced upon evacuation for every sample, and the 110 reflection of clinoptilolite at 7.35{sup 0}2 {theta} became obvious, whereas it was not in the untreated samples. These data show that the effects of heating on the unit-cell volume of clinoptilolite depend strongly on the exchangeable cation content. Significant reductions in the unit-cell volumes of natural, mixed Na-K-Ca clinoptilolites could take place in rocks in a repository environment, particularly if the clinoptilolites occurred in unsaturated, dehydrated rock. The unit-cell volumes of clinoptilolites in partially saturated rocks at temperatures below 100{sup 0}C, however, should not decrease significantly.

  17. Effect of blastfurnace slag addition to Portland cement for cationic exchange resins encapsulation

    Directory of Open Access Journals (Sweden)

    Stefan L.

    2013-07-01

    Full Text Available In the nuclear industry, cement-based materials are extensively used to encapsulate spent ion exchange resins (IERs before their final disposal in a repository. It is well known that the cement has to be carefully selected to prevent any deleterious expansion of the solidified waste form, but the reasons for this possible expansion are not clearly established. This work aims at filling the gap. The swelling pressure of IERs is first investigated as a function of ions exchange and ionic strength. It is shown that pressures of a few tenths of MPa can be produced by decreases in the ionic strength of the bulk solution, or by ion exchanges (2Na+ instead of Ca2+, Na+ instead of K+. Then, the chemical evolution of cationic resins initially in the Na+ form is characterized in CEM I (Portland cement and CEM III (Portland cement + blastfurnace slag cements at early age and an explanation is proposed for the better stability of CEM III material.

  18. Independent control of the shape and composition of ionic nanocrystals through sequential cation exchange reactions

    Energy Technology Data Exchange (ETDEWEB)

    Luther, Joseph Matthew; Zheng, Haimei; Sadtler, Bryce; Alivisatos, A. Paul

    2009-07-06

    Size- and shape-controlled nanocrystal growth is intensely researched for applications including electro-optic, catalytic, and medical devices. Chemical transformations such as cation exchange overcome the limitation of traditional colloidal synthesis, where the nanocrystal shape often reflects the inherent symmetry of the underlying lattice. Here we show that nanocrystals, with established synthetic protocols for high monodispersity, can be templates for independent composition control. Specifically, controlled interconversion between wurtzite CdS, chalcocite Cu2S, and rock salt PbS occurs while preserving the anisotropic dimensions unique to the as-synthesized materials. Sequential exchange reactions between the three sulfide compositions are driven by the disparate solubilites of the metal ion exchange pair in specific coordinating molecules. Starting with CdS, highly anisotropic PbS nanorods are created, which serve as an important material for studying strong 2-dimensional quantum confinement, as well as for optoelectronic applications. Furthermore, interesting nanoheterostructures of CdS|PbS are obtained by precise control over ion insertion and removal.

  19. Formation of ZnSe/Bi2Se3 QDs by surface cation exchange and high photothermal conversion

    Directory of Open Access Journals (Sweden)

    Guozhi Jia

    2015-08-01

    Full Text Available Water-dispersed core/shell structure ZnSe/Bi2Se3 quantum dots were synthesized by ultrasonicwave-assisted cation exchange reaction. Only surface Zn ion can be replaced by Bi ion in ZnSe quantum dots, which lead to the ultrathin Bi2Se3 shell layer formed. It is significance to find to change the crystal of QDs due to the acting of ultrasonicwave. Cation exchange mechanism and excellent photothermal conversion properties are discussed in detail.

  20. Controlled methyl-esterification of pectin catalyzed by cation exchange resin.

    Science.gov (United States)

    Peng, Xiaoxia; Yang, Guang; Fan, Xingchen; Bai, Yeming; Ren, Xiaomeng; Zhou, Yifa

    2016-02-10

    This study developed a new method to methyl-esterify pectin using a cation exchange resin. Homogalacturonan (HG)-type pectin (WGPA-3-HG) and rhamnogalacturonan (RG)-I-type pectin (AHP-RG) obtained from the roots of Panax ginseng and sunflower heads, respectively, were used as models. Compared to commonly used methyl-esterification methods that use either methyl iodide or acidified methanol, the developed method can methyl-esterify both HG- and RG-I-type pectins without degrading their structures via β-elimination or acid hydrolysis. In addition, by modifying reaction conditions, including the mass ratio of resin to pectin, reaction time, and temperature, the degree of esterification can be controlled. Moreover, the resin and methanol can be recycled to conserve resources, lower costs, and reduce environmental pollution. This new methodology will be highly useful for industrial esterification of pectin.

  1. Behavior of human serum albumin on strong cation exchange resins: II. model analysis.

    Science.gov (United States)

    Voitl, Agnes; Butté, Alessandro; Morbidelli, Massimo

    2010-08-20

    Experiments with human serum albumin on a strong cation exchange resin exhibit a peculiar elution pattern: the protein elutes with two peaks in a modifier gradient. This behavior is modeled with a general rate model, where the two elution peaks are modeled with two binding conformations, one of which is at equilibrium conditions, while for the other, the adsorption process is rate limited. Isocratic experiments under nonadsorbing conditions were used to characterize the mass transfer process. The isotherm of both adsorption conformations as well as the kinetic of adsorption and desorption for the second conformation are functions of the modifier concentration. They are evaluated with linear modifier gradient experiments and step experiments with various adsorption times. All experimental features are well reproduced by the proposed modified general rate model.

  2. Strong Cation Exchange Chromatography in Analysis of Posttranslational Modifications: Innovations and Perspectives

    Directory of Open Access Journals (Sweden)

    Mariola J. Edelmann

    2011-01-01

    Full Text Available Strong cation exchange (SCX chromatography has been utilized as an excellent separation technique that can be combined with reversed-phase (RP chromatography, which is frequently used in peptide mass spectrometry. Although SCX is valuable as the second component of such two-dimensional separation methods, its application goes far beyond efficient fractionation of complex peptide mixtures. Here I describe how SCX facilitates mapping of the protein posttranslational modifications (PTMs, specifically phosphorylation and N-terminal acetylation. The SCX chromatography has been mainly used for enrichment of these two PTMs, but it might also be beneficial for high-throughput analysis of other modifications that alter the net charge of a peptide.

  3. Influence of montmorillonites exchange capacity on the basal spacing of cation–anion organo-montmorillonites

    Energy Technology Data Exchange (ETDEWEB)

    Sanqin, Wu [School of Materials Sciences and Technology, China University of Geosciences, No. 29 Xueyuan Road, Beijing, 100083 (China); Zepeng, Zhang, E-mail: unite508@163.com [School of Materials Sciences and Technology, China University of Geosciences, No. 29 Xueyuan Road, Beijing, 100083 (China); Yunhua, Wang [Zhejiang Fenghong New Material Co., Ltd. (China); Libing, Liao [School of Materials Sciences and Technology, China University of Geosciences, No. 29 Xueyuan Road, Beijing, 100083 (China); Jiansheng, Zhang [Tangshan College, Tangshan 063000 (China)

    2014-11-15

    Graphical abstract: This picture shows the distribution of organic modifier (CTAB and SDS) in Mt interlayer and the basal spacing changes of Mt modified by CTAB and SDS. Organic modifier molecule in Mt interlayer is more and more orderly. The basal spacing of Mt is from 1.5 nm to 5 nm as modifier added. - Highlights: • The d{sub 001} of Ca-Mt, R-Na-Mt, Na-Mt modified by CTAB and SDS can reach 5 nm. • It is easier to get cation–anion OMt with greater d{sub 001} if CEC is lower. • The organic molecules distribution in cation–anion OMt was analyzed. • The influence mechanism of Ca-Mt CEC on the d{sub 001} was discussed. - Abstract: With cationic and anionic surfactants cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfonate (SDS) as modifiers, Ca-montmorillonites (Ca-Mt), artificial Na-montmorillonites (R-Na-Mt) and natural Na-montmorillonites (Na-Mt) with different cation exchange capacity (CEC) were modified by solution intercalation method, respectively. Then cation–anion organo-montmorillonites (OMt) were prepared. The influence of CEC on the basal spacing of cation–anion OMt and the influence mechanism were discussed by X-ray diffraction (XRD) and zeta potential testing. The results indicate that the basal spacing of cation–anion OMt is related to CEC. For the same type montmorillonites, the basal spacing of cation–anion OMt decreases with the increase of CEC and it is easier to get cation–anion OMt with greater basal spacing when CEC is lower. Moreover, the CEC of Na-Mt has the greatest influence on the basal spacing of cation–anion OMt.

  4. Fractionation of whey proteins with high-capacity superparamagnetic ion-exchangers

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Justesen, Sune; Thomas, Owen R. T.

    2004-01-01

    In this study we describe the design, preparation and testing of superparamagnetic anion-exchangers, and their use together with cation-exchangers in the fractionation of bovine whey proteins as a model study for high-gradient magnetic fishing. Adsorbents prepared by attachment of trimethyl amine...... to 337 mg g-1 with a dissociation constant of 0.042 µM. The latter anion-exchanger was selected for studies of whey protein fractionation. In these, crude bovine whey was treated with a superparamagnetic cation-exchanger to adsorb basic protein species, and the supernatant arising from this treatment......) was achieved with some simultaneous binding of immunoglobulins (Ig). The immunoglobulins were separated from the other two proteins by desorbing with a low concentration of NaCl (=0.4 M), whereas lactoferrin and lactoperoxidase were co-eluted in significantly purer form, e.g. lactoperoxidase was purified 28...

  5. Fractionation of whey proteins with high-capacity superparamagnetic ion-exchangers

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Justesen, S.F.L.; Thomas, Owen R. T.

    2004-01-01

    In this study we describe the design, preparation and testing of superparamagnetic anion-exchangers, and their use together with cation-exchangers in the fractionation of bovine whey proteins as a model study for high-gradient magnetic fishing. Adsorbents prepared by attachment of trimethyl amine...... to 337 mg g(-1) with a dissociation constant of 0.042 muM. The latter anion-exchanger was selected for studies of whey protein fractionation. In these, crude bovine whey was treated with a superparamagnetic cation-exchanger to adsorb basic protein species, and the supernatant arising from this treatment......) was achieved with some simultaneous binding of immunoglobulins (1g). The immunoglobulins were separated from the other two proteins by desorbing with a low concentration of NaCl (less than or equal to0.4 M), whereas lactoferrin and lactoperoxidase were co-eluted in significantly purer form, e...

  6. A DFT-D study of the interaction of methane, carbon monoxide, and nitrogen with cation-exchanged SAPO-34

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Michael [Bremen Univ. (Germany). Fachgebiet Kristallographie; University College London (United Kingdom). Dept. of Chemistry; Bell, Robert G. [University College London (United Kingdom). Dept. of Chemistry

    2015-07-01

    Density-functional theory calculations including a semi-empirical dispersion correction (DFT-D) are employed to study the interaction of small guest molecules (CH{sub 4}, CO, N{sub 2}) with the cation sites in the silicoaluminophosphate SAPO-34. Eight different cations from three different groups (alkali cations, alkaline earth cations, transition metals) are included in the study. For each case, the total interaction energy as well as the non-dispersive contribution to the interaction are analysed. Electron density difference plots are used to investigate the nature of this non-dispersive contribution in more detail. Despite a non-negligible contribution of polarisation interactions, the total interaction remains moderate in systems containing main group cations. In SAPOs exchanged with transition metals, orbital interactions between the cations and CO and N{sub 2} lead to a very strong interaction, which makes these systems attractive as adsorbents for the selective adsorption of these species. A critical comparison with experimental heats of adsorption shows reasonable quantitative agreement for CO and N{sub 2}, but a pronounced overestimation of the interaction strength for methane. While this does not affect the conclusions regarding the suitability of TM-exchanged SAPO-34 materials for gas separations, more elaborate computational approaches may be needed to improve the quantitative accuracy for this guest molecule.

  7. Surface modification of cation exchange membranes by graft polymerization of PAA-co-PANI/MWCNTs nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nemati, Mahsa; Hosseini, Sayed Mohsen; Bagheripour, Ehsan [Faculty of Engineering, Arak University, Arak (Iran, Islamic Republic of); Madaeni, Sayed Siavash [Faculty of Engineering, Razi University, Kermanshah (Iran, Islamic Republic of)

    2016-03-15

    Surface modification of polyvinylchloride based heterogeneous cation exchange membrane was performed by graft polymerization of PAA and PAA-co-PANI/MWCNTs nanoparticles. The ion exchange membranes were prepared by solution casting technique. Spectra analysis confirmed graft polymerization clearly. SEM images illustrated that graft polymerization covers the membranes by simple gel network entanglement. The membrane water content was decreased by graft polymerization of PAA-co-PANI/MWCNTs nanoparticles on membrane surface. Membrane transport number and selectivity declined initially by PAA graft polymerization and then began to increase by utilizing of composite nanoparticles in modifier solution. The sodium and barium flux was improved sharply by PAA and PAAco- 0.01%wt PANI/MWCNTs graft polymerization on membrane surface and then decreased again by more increase of PANI/MWCNTs nanoparticles content ratio in modifier solution. The electrodialysis experiment results in laboratory scale showed higher dialytic rate in heavy metals removal for grafted-PAA and grafted-PAA-co-PANI/MWCNTs modified membrane compared to pristine one. Membrane areal electrical resistance was also decreased by introducing graft polymerization of PAA and PAA-co-PANI/MWCNTs NPs on membrane surface.

  8. SYNTHESIS OF 1—(N—BENZYLOXYCARBONYLAMINO)ALKANEPHOSPHATES AND—PHOSPHINIC ACIDS CATALYZED BY A CATION EXCHANGE RESIN

    Institute of Scientific and Technical Information of China (English)

    ZHANGYuehua; HUANGWenqiang; 等

    1993-01-01

    An improved method is developed by using strongly acidic cation exchange resin(001×1,H+ form) as a catalyst for the synthesis of diphenyl 1-(N-benzyloxycarbonyl-amino) alkanephosphonates and 1-(N-benzyloxycarbonylamino) alkanephenyl phosphinic acids in high yields.

  9. Luminescent CuInS2 quantum dots by partial cation exchange in Cu2- xS nanocrystals

    NARCIS (Netherlands)

    Van Der Stam, Ward; Berends, Anne C.; Rabouw, Freddy T.; Willhammar, Tom; Ke, Xiaoxing; Meeldijk, Johannes D.; Bals, Sara; De Mello Donega, Celso

    2015-01-01

    Here, we show successful partial cation exchange reactions in Cu2-xS nanocrystals (NCs) yielding luminescent CuInS2 (CIS) NCs. Our approach of mild reaction conditions ensures slow Cu extraction rates, which results in a balance with the slow In incorporation rate. With this method, we obtain CIS NC

  10. Preparation and characterisation of monovalent ion selective cation exchange membranes based on sulphonated poly(ether ether ketone)

    NARCIS (Netherlands)

    Balster, J.; Krupenko, O.; Punt, I.G.M.; Stamatialis, D.; Wessling, M.

    2005-01-01

    This paper analyses the separation properties of various commercial cation exchange membranes (CEMs) and tailor made membranes based on sulphonated poly(ether ether ketone) and poly(ether sulphone) for binary electrolyte solutions containing protons and calcium ions. All membranes are thoroughly cha

  11. SYNTHESIS OF 2—HYDROXYETHYL ACRYLATE BY USING STRONG ACIDIC CATION ION EXCHANGE RESIN AS CATALYST

    Institute of Scientific and Technical Information of China (English)

    GAODabin

    1992-01-01

    2-Hydroxyethyl acrylate is synthesized from acrylic acid and ethylene glycol under a simple and mild condition by using strong acidic cation ion exchange resin as a catalyst,which could be recycled as long as 10 times with high activation.

  12. A study on equilibrium and kinetics of ion exchange of alkaline earth metals using an inorganic cation exchanger - zirconium titanium phosphate

    Indian Academy of Sciences (India)

    Amin Jignasa; Thakkar Rakesh; Chudasama Uma

    2006-03-01

    An advanced inorganic cation exchange material of the class of tetravalent metal acid (TMA) salt, zirconium titanium phosphate (ZTP), has been synthesized by a modified sol-gel technique. ZTP has been characterized by elemental analysis (ICP-AES), thermal analysis (TGA), FTIR and X-ray diffraction studies. The Nernst-Planck equation has been used to study the forward and reverse ion exchange kinetics of Mg (II), Ca (II), Sr (II) and Ba (II) with H (I) at four different temperatures. The mechanism of exchange is particle diffusion, as confirmed by the linear (dimensionless time parameter) vs (time) plots. The exchange process is thus controlled by the diffusion within the exchanger particles for the systems studied herein. Further, various kinetic parameters like self-diffusion coefficient (0), energy of activation () and entropy of activation (*) have been evaluated under conditions favouring a particle diffusion-controlled mechanism.

  13. 1H and 23Na MAS NMR spectroscopy of cationic species in CO2 selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    Science.gov (United States)

    Arévalo-Hidalgo, Ana G.; Dugar, Sneha; Fu, Riqiang; Hernández-Maldonado, Arturo J.

    2012-07-01

    The location of extraframework cations in Sr2+ and Ba2+ ion-exchanged SAPO-34 was estimated by means of 1H and 23Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO2 adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium.

  14. Cationic Polymerization of 1,2-Epoxypropane by an Acid Exchanged Montmorillonite Clay in the Presence of Ethylene Glycol

    Directory of Open Access Journals (Sweden)

    Aïcha Hachemaoui

    2003-10-01

    Full Text Available Abstract: The polymerization of propylene oxide (PO catalysed by maghnite-H+ (mag-H+ in the presence of ethylene glycol was investigated. Mag-H+ is a montmorillonite silicate sheet clay was prepared through a straight forward proton exchange process. It was found that the cationic polymerization of PO was initiated by mag-H+ at 20 °C both in bulk and in solution. The effect of the amount of mag-H+ and solvent was studied. These results indicated the cationic nature of the polymerization A possible initiation pathway, via the transfer of protons from mag-H+ to the monomer, is proposed.

  15. Influence of competing inorganic cations on the ion exchange equilibrium of the monovalent organic cation metoprolol on natural sediment.

    Science.gov (United States)

    Niedbala, Anne; Schaffer, Mario; Licha, Tobias; Nödler, Karsten; Börnick, Hilmar; Ruppert, Hans; Worch, Eckhard

    2013-02-01

    The aim of this study was to systematically investigate the influence of the mono- and divalent inorganic ions Na(+) and Ca(2+) on the sorption behavior of the monovalent organic cation metoprolol on a natural sandy sediment at pH=7. Isotherms for the beta-blocker metoprolol were obtained by sediment-water batch tests over a wide concentration range (1-100000 μg L(-1)). Concentrations of the competing inorganic ions were varied within freshwater relevant ranges. Data fitted well with the Freundlich sorption model and resulted in very similar Freundlich exponents (n=0.9), indicating slightly non-linear behavior. Results show that the influence of Ca(2+) compared to Na(+) is more pronounced. A logarithmic correlation between the Freundlich coefficient K(Fr) and the concentration or activity of the competing inorganic ions was found allowing the prediction of metoprolol sorption on the investigated sediment at different electrolyte concentrations. Additionally, the organic carbon of the sediment was completely removed for investigating the influence of organic matter on the sorption of metoprolol. The comparison between the experiments with and without organic carbon removal revealed no significant contribution of the organic carbon fraction (0.1%) to the sorption of metoprolol on the in this study investigated sediment. Results of this study will contribute to the development of predictive models for the transport of organic cations in the subsurface.

  16. Use of Cation Exchange Membrane in Soil Potassium Release and Wheat Response to Potassium

    Institute of Scientific and Technical Information of China (English)

    LIGUI-BAO; J.J.SCHOENAU; 等

    1995-01-01

    A pot experiment was conducted in the growth chamber on Saskatchewan soils with different texture to determine the K release status and wheat K demand.The relationship between K uptake and soil available K extracted by cation exchange membrane(CEM-K) and the effcet of K fertilizer on wheat growth and soil available K was also evaluated.Treatments of 0,60 and 120mg K/kg were applied to sandy,low and high K loamy and clay soils,The highest yields were acieved with the application of 120mg K/kg in sandy soil and 60 mg K/kg in other soils.On the whole,the clay soil contributed K more than other soils from slowly available fraction.Regression revealed a linear relationship between the soil available K extracted by NH4OAc(Ka) and CEM-K in suspensions(r=0.93).Results also showed that CEM-K in burial and in suspensions were different not only in the amount but also in correlation with Ka or K uptake.

  17. Cation exchange displacement batch chromatography of proteins guided by screening of protein purification parameters.

    Science.gov (United States)

    Kotasińska, Marta; Richter, Verena; Thiemann, Joachim; Schlüter, Hartmut

    2012-11-01

    Displacement chromatography has been shown to be an effective alternative for protein purification. We investigated in this study sample displacement chromatography, which does not require a displacer molecule. Furthermore, we performed a screening for determination of parameters for an optimal sample displacement chromatography. We screened the affinities of cytochrome C, lysozyme, myoglobin, and ribonuclease A toward a cation exchange material as a function of different pH values and to presence of different concentrations of sodium chloride in the sample application buffer. Sample displacement chromatography in batch chromatography mode for the separation of the protein mixture was studied with a sample application buffer with a pH of 5 and 7. As predicted by the screening experiments, sample displacement chromatography was most effective at pH 7 since this pH guaranteed the largest differences of the affinities of the four proteins toward the stationary phase. In summary, we describe here sample displacement chromatography in the batch chromatography mode for the separation of proteins, which is a simple and fast alternative to conventional displacement chromatography. Systematic screening of chromatographic parameters prior to sample displacement chromatography promises a successful separation of a target protein.

  18. Strong cation exchange resin for improving physicochemical properties and sustaining release of ranitidine hydrochloride

    Directory of Open Access Journals (Sweden)

    Khan S

    2007-01-01

    Full Text Available In the present study strong cation exchange resin (Amberlite IRP69 was used to improve the physicochemical properties of ranitidine hydrochloride such as taste and bulk properties and to sustain dissolution rate. Drug-resin complexes were prepared using batch method. Drug loading was done under different processing conditions such as temperature, pH, drug-resin ratio, and drug concentration to get the optimum condition for resinate preparation. Resinate prepared under optimized condition was tested for taste, bulk properties and release rate. Degree of bitterness of ranitidine was found to reduce to zero after complexation with resin. Improvement in flow properties was also observed. Angle of repose for resinate was found to be 33.21 o as compared to 42.27 o for ranitidine HCl. Effect of dissolution medium and particle size on in vitro release of drug from resinate was also investigated. Resinate with drug to resin ratio of 2:3 and particle size> 90 µm showed about 90% of drug release within 12 h. The orodispersible tablet formulated from the resinate containing 10% croscarmellose sodium disintegrated within 35 sec in oral cavity and showed similar dissolution profile as the resinate. Tablets were found stable after stability studies with no change in dissolution profile.

  19. Assessing Soil Available Potassium by Cation Exchange Membrane and COnventional Chemical Extractions

    Institute of Scientific and Technical Information of China (English)

    LIUZHAOHUI; J.SCHOENAU; 等

    1999-01-01

    Four testing methods using cation exchange membrane (CEM),ammonium acetate,ASI(0.25mol L-1 NaHCO3+0.01mol L-1 EDTA +0.01 molL-1 NH4F) and 1.0molL-1 boiling nitric acid,respectively,were used to evaluate soil available K.The soil K tested by CEM was significantly correlated with that by the other (conventional)methods(r2=0.43**-0.95***).The soil K tested by CEM saturated with NH4HCO3(15min extraction)was most closely correlated with that by the other methods(r2=0.60**-0.95***),Potassium availability,as predicted by soil test,was comparable to actual K uptake by canola and wheat grown on the soils in growth chamber.Regression analyses showed that plant K uptake was more closely correlated wiht K extracted by CEM(r2=0.56**-0.81***)than that by the conventional methods(r2=0.46***-0.81***),most colsely correlated with that by NH4HCO3-saturated CEM for 15 min (r2=0.81***).and worst correlated with that by HNO3(r2=0.45**-0.72***)

  20. Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction.

    Science.gov (United States)

    Kang, Il-Mo; Roh, Ki-Min

    2013-01-01

    The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCI solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2 gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3 polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (approximately 98 wt%).

  1. Cation- and anion-exchanges induce multiple distinct rearrangements within metallosupramolecular architectures.

    Science.gov (United States)

    Riddell, Imogen A; Ronson, Tanya K; Clegg, Jack K; Wood, Christopher S; Bilbeisi, Rana A; Nitschke, Jonathan R

    2014-07-01

    Different anionic templates act to give rise to four distinct Cd(II)-based architectures: a Cd2L3 helicate, a Cd8L12 distorted cuboid, a Cd10L15 pentagonal prism, and a Cd12L18 hexagonal prism, which respond to both anionic and cationic components. Interconversions between architectures are driven by the addition of anions that bind more strongly within a given product framework. The addition of Fe(II) prompted metal exchange and transformation to a Fe4L6 tetrahedron or a Fe10L15 pentagonal prism, depending on the anionic templates present. The equilibrium between the Cd12L18 prism and the Cd2L3 triple helicate displayed concentration dependence, with higher concentrations favoring the prism. The Cd12L18 structure serves as an intermediate en route to a hexafluoroarsenate-templated Cd10L15 complex, whereby the structural features of the hexagonal prism preorganize the system to form the structurally related pentagonal prism. In addition to the interconversion pathways investigated, we also report the single-crystal X-ray structure of bifluoride encapsulated within a Cd10L15 complex and report solution state data for J-coupling through a CH···F(-) hydrogen bond indicating the strength of these interactions in solution.

  2. Oxidative decomposition properties of cationic exchange resins producing SO4(2-) in power plants.

    Science.gov (United States)

    Zhu, Zhiping; Dai, Chenlin; Liu, Sen; Tian, Ye

    2015-01-01

    The sulphate content of a system increases when strong-acid cationic exchange resins leak into a system or when sulphonic acid groups on the resin organic chain detach. To solve this problem, a dynamic cycle method was used in dissolution experiments of several resins under H2O2 or residual chlorine conditions. Results show that after performing dynamic cycle experiments for 120 hours under oxidizing environments, the SO4(2-) and total organic carbon (TOC) released by four kinds of resins increased with time, contrary to their release velocity. The quantity of released SO4(2-) increased as the oxidizing ability of oxidants was enhanced. Results showed that the quantity and velocity of released SO4(2-) under residual chlorine condition were larger than those under H2O2 condition. Data analysis of SO4(2-) and TOC released from the four kinds of resins by the dynamic cycle experiment revealed that the strength of oxidation resistance of the four resins were as follows: 650C>1500H>S200>SP112H.

  3. Determination of some aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography with conductimetric detection on a weakly acidic cation-exchange resin column.

    Science.gov (United States)

    Ito, Kazuaki; Takayama, Yohichi; Ikedo, Mikaru; Mori, Masanobu; Taoda, Hiroshi; Xu, Qun; Hu, Wenzhi; Sunahara, Hiroshi; Hayashi, Tsuneo; Sato, Shinji; Hirokawa, Takeshi; Tanaka, Kazuhiko

    2004-06-11

    The determination of seven aliphatic carboxylic acids, formic, acetic, propionic, isobutyric, n-butyric, isovaleric and n-valeric acids in anaerobic digestion process waters was examined using ion-exclusion chromatography with conductimetric detection. The analysis of these biologically important carboxylic acids is necessary as a measure for evaluating and controlling the process. The ion-exclusion chromatography system employed consisted of polymethacrylate-based weakly acidic cation-exchange resin columns (TSKgel OApak-A or TSKgel Super IC-A/C). weakly acidic eluent (benzoic acid), and conductimetric detection. Particle size and cation-exchange capacity were 5 microm and 0.1 meq./ml for TSKgel OApak-A and 3 microm and 0.2 meq./ml for TSKgel Super IC-A/C, respectively. A dilute eluent (1.0-2.0 mM) of benzoic acid was effective for the high resolution and highly conductimetric detection of the carboxylic acids. The good separation of isobutyric and n-butyric acids was performed using the TSKgel Super IC-A/C column (150 mm x 6.0 mm i.d. x 2). The simple and good chromatograms were obtained by the optimized ion-exclusion chromatography conditions for real samples from mesophilic anaerobic digestors, thus the aliphatic carboxylic acids were successfully determined without any interferences.

  4. Fabrication, characterization and photocatalytic properties of Ag/AgI/BiOI heteronanostructures supported on rectorite via a cation-exchange method

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yunfang [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Fang, Jianzhang, E-mail: fangjzh@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China); Lu, Shaoyou [Shenzhen Center for Disease Control and Prevention, Shenzhen 518055 (China); Wu, Yan; Chen, Dazhi; Huang, Liyan [Institute of Engineering Technology of Guangdong Province, Key Laboratory of Water Environmental Pollution Control of Guangdong Province, Guangzhou 510440 (China); Xu, Weicheng; Zhu, Ximiao [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Fang, Zhanqiang [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China)

    2015-04-15

    Highlights: • Ag/AgI/BiOI-rectorite was prepared by twice cation-exchange process. • Ag/AgI/BiOI-rectorite photocatalyst possessed SPR and adsorption capacity. • Ag/AgI/BiOI-rectorite exhibited highly photocatalytic activity. • Trapped holes and ·O{sub 2}{sup −} were formed active species in the photocatalytic system. - Abstract: In this work, a new plasmonic photocatalyst Ag/AgI/BiOI-rectorite was prepared via a cation exchange process. The photocatalyst had been characterized by X-ray powder diffraction (XRD), Raman spectra, nitrogen sorption (BET), field-emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity, which was evaluated by degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation, was enhanced significantly by loading Ag/AgI/BiOI nanoparticles onto rectorite. The photogenerated holes and superoxide radical (·O{sub 2}{sup −}) were both formed as active species for the photocatalytic reactions under visible light irradiation. The existence of metallic Ag particles, which possess the surface plasmon resonance effect, acted as an indispensable role in the photocatalytic reaction.

  5. Ionic polymer-metal composite actuators obtained from radiation-grafted cation- and anion-exchange membranes.

    Science.gov (United States)

    Park, Jong Hyuk; Han, Man Jae; Song, Dae Seock; Jho, Jae Young

    2014-12-24

    Two series of ionic polymer-metal composites (IPMCs), one cationic and one anionic, are designed and prepared from radiation-grafted ion-exchange membranes. Through examination of the properties of the membranes synthesized from the two grafting monomers and the two base polymers, acrylic acid-grafted poly(vinylidene fluoride-co-hexafluoropropylene) and quarternized 4-vinylpyridine-grafted poly(ethylene-co-tetrafluoroethylene) with the appropriate amount of ionic groups are employed for the fabrication of cation and anion IPMCs, respectively. The bending displacement of the cation IPMC is comparable to Nafion-based IPMC under direct- and alternating-current voltage, but back-relaxation is not observed. The actuation performance of the anion IPMC is highly improved over those reported earlier in the literature for the other anion IPMCs.

  6. Separation of matrine and oxymatrine from Sophora flavescens extract through cation exchange resin coupled with macroporous absorption resin

    Directory of Open Access Journals (Sweden)

    Chen Haohao

    2016-06-01

    Full Text Available A simple method for separation of matrine and oxymatrine from Sophora flavescens was developed with cation exchange resin coupled with macroporous resin. Based on the adsorption characteristics of matrine and oxymatrine, 001×732 cation exchange resin was used to absorb target alkaloids for removing most of the foreign matter, while BS-65 macroporous resin was chosen to purify these alkaloids. The result showed that the equilibrium adsorption data of matrine and oxymatrine on 001×732 resin and BS-65 resin at 30°C was fitted to Langmuir isotherm and Freundlich isotherm, respectively. The contents of matrine and oxymatrine were increased from 0.73% and 2.2% in the crude extract of the root of Sophora flavescens to 67.2% and 66.8% in the final eluent products with the recoveries of 90.3% and 86.9%, respectively.

  7. The load and release characteristics on a strong cationic ion-exchange fiber: kinetics, thermodynamics, and influences.

    Science.gov (United States)

    Yuan, Jing; Gao, Yanan; Wang, Xinyu; Liu, Hongzhuo; Che, Xin; Xu, Lu; Yang, Yang; Wang, Qifang; Wang, Yan; Li, Sanming

    2014-01-01

    Ion-exchange fibers were different from conventional ion-exchange resins in their non-cross-linked structure. The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion. Therefore, this work aimed to investigate the load and release characteristics of five model drugs with the strong cationic ion-exchange fiber ZB-1. Drugs were loaded using a batch process and released in United States Pharmacopoeia (USP) dissolution apparatus 2. Opposing exchange kinetics, suitable for the special structure of the fiber, were developed for describing the exchange process with the help of thermodynamics, which illustrated that the load was controlled by an ionic reaction. The molecular weight was the most important factor to influence the drug load and release rate. Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences. The drug-fiber complexes exhibited sustained release. Different kinds and concentrations of counter ions or different amounts of drug-fiber complexes in the release medium affected the release behavior, while the pH value was independent of it. The groundwork for in-depth exploration and further application of ion-exchange fibers has been laid.

  8. Cation-exchange high-performance liquid chromatography: Separation of highly basic proteins using volatile acidic solvents

    NARCIS (Netherlands)

    Eijnden-van Raaij, A.J.M. van den; Koornneef, I.; Oostwaard, Th.M.J.; Laat, S.W. de; Zoelen, E.J.J. van

    1987-01-01

    The chromatographic behavior of a number of globular proteins was studied on a Bio-Sil TSK CM-2-SW weak cation exchange HPLC column under acidic conditions. A linear gradient of O-I M NH₄Ac in I M HOAc, inducing a convex pH gradient from 2.4-4.8, resulted in an excellent separation of highly basic p

  9. Superparamagnetic cation-exchange adsorbents for bioproduct recovery from crude process liquors by high-gradient magnetic fishing

    DEFF Research Database (Denmark)

    Heebøll-Nielsen, Anders; Justesen, S.F.L; Hobley, Timothy John;

    2004-01-01

    Different routes were screened for the preparation of superparamagnetic cation-exchange adsorbents for the capture of proteins using high-gradient magnetic fishing. Starting from a polyglutaraldehyde-coated base particle, the most successful of these involved attachment of sulphite to oligomers...... from sweet bovine whey. Subsequently, a high-gradient magnetic fishing process was constructed for the fractionation of whey, in which lactoperoxidase was purified 36-fold and concentrated 4.7-fold...

  10. FACTORS AFFECT THE RELEASE OF PSEUDOEPHDRINE HYDROCHLORIDE FROM THE UNCOATED CATION EXCHANGE RESIN-BASED DRUG DELIVERY SYSTEM IN VITRO

    Institute of Scientific and Technical Information of China (English)

    LI Zhenhua; PI Hongqiong; HE Binglin

    2001-01-01

    In this paper, it was investigated that the effect of parameters such as the ionic strength,pH, counter-ion type of release medium, particle size, and cross linkage of cation exchange resin on the release of model drug pseudoephedrine hydrochloride (PE) from uncoated drug-resin complex.The drug-resin complex was prepared by the reaction of PE with strongly acidic cation exchange resin (001 ×4, 001 ×7, 001 ×14). The result showed that the loading of PE increased with the increase of temperatures. The release of PE from drug-resin complex at 37 ℃ was monitored in vitro.From the experiments, it was found that the release rate of PE depends on the pH, composition of the releasing media, increased at lower pH media or with increase of ionic strength of media. Moreover,the release rate of PE was inversely proportional to the cross-linkage and particle size of the cation exchange resin.

  11. A weak cation-exchange monolith as stationary phase for the separation of peptide diastereomers by CEC.

    Science.gov (United States)

    Ludewig, Ronny; Nietzsche, Sandor; Scriba, Gerhard K E

    2011-01-01

    A CEC weak cation-exchange monolith has been prepared by in situ polymerization of acrylamide, methylenebisacrylamide and 4-acrylamidobutyric acid in a decanol-dimethylsulfoxide mixture as porogen. The columns were evaluated by SEM and characterized with regard to the separation of diastereomers and α/β-isomers of aspartyl peptides. Column preparation was reproducible as evidenced by comparison of the analyte retention times of several columns prepared simultaneously. Analyte separation was achieved using mobile phases consisting of acidic phosphate buffer and ACN. Under these conditions the peptides migrated due to their electrophoretic mobility but the EOF also contributed as driving force as a function of the pH of the mobile phase due to increasing dissociation of the carboxyl groups of the polymer. Raising the pH of the mobile phase also resulted in deprotonation of the peptides reducing analyte mobility. Due to these mechanisms each pair of diastereomeric peptides displayed the highest resolution at a different pH of the buffer component of the mobile phase. Comparing the weak-cation exchange monolith to an RP monolith and a strong cation-exchange monolith different elution order of some peptide diastereomers was observed, clearly illustrating that interactions with the stationary phase contribute to the CEC separations.

  12. FACTORS AFFECT THE RELEASE OF PSEUDOEPHDRINE HYDROCHLORIDE FROM THE UNCOATED CATION EXCHANGE RESIN—BASED DRUG DELIVERY SYSTEM IN VITRO

    Institute of Scientific and Technical Information of China (English)

    LIZhenhua; PIHongqiong; 等

    2001-01-01

    In this paper,it was investigated that the effect of parameters such as the ionic strength,pH.counter-ion type of release medium,particle size.and cross linkage of cation exchange resin on the release of model drug pseudoephedrine hydrochloride(PE) from uncoated drug-resin complex.The drug-resin complex was pepared by the reaction of PE with strongly acidic cation exchange resin(001×4,001×7,001×14) .The result showed that the loading of PE increased with the increase of temperatures.The release of PE from drug-resin complex at 37℃ was monitored in vitro.From the experiments,it was found that the release rate of PE depends on the pH.comosition of the releasing media,increased at lower pH media or with increase of ionic strength of media.Moreover,the release rate of PE was inversely proportional to the cross-linkage and particle size of the cation exchange resin.

  13. Sorption of chlorimuron-ethyl on montmorillonite clays: effects of exchangeable cations, pH, and ionic strength.

    Science.gov (United States)

    Ren, Wenjie; Teng, Ying; Zhou, Qixing; Paschke, Albrecht; Schüürmann, Gerrit

    2014-10-01

    Sorption interaction of chlorimuron-ethyl with montmorillonite clays was investigated under varied types of exchangeable cation, pH, and ionic strength conditions. Chlorimuron-ethyl sorption on bentonites exhibited pronounced cation dependency, and the sorption ability increased as the sequence Ca(2+)- clay type and much weaker for montmorillonites. The decrease of pH at the range of 4.0-6.0 prominently increased sorption of chlorimuron-ethyl on all cation-exchanged montmorillonite clays, and nearly a neglected sorption (about 2 %) can be observed at pH over 7.0. In the presence of CaCl2, sorption of chlorimuron-ethyl on Fe(3+)-bentonite was promoted because of complexion of Ca(2+) and the surface of Fe(3+)-bentonite. However, as the concentration of CaCl2 increased, chlorimuron-ethyl sorption on Ca(2+)- and Fe(3+)-exchanged bentonite decreased, suggesting that Ca bridging was not the prevailing mechanism for sorption of chlorimuron-ethyl on these clays. Furthermore, chlorimuron-ethyl sorption was relatively sensitive to pH, and the change of pH may obscure effect of other factors on the sorption, so it was quite necessary to control pH at a constant value when the effect of other factor was being studied.

  14. Probing the Complementarity of FAIMS and Strong Cation Exchange Chromatography in Shotgun Proteomics

    Science.gov (United States)

    Creese, Andrew J.; Shimwell, Neil J.; Larkins, Katherine P. B.; Heath, John K.; Cooper, Helen J.

    2013-03-01

    High field asymmetric waveform ion mobility spectrometry (FAIMS), also known as differential ion mobility spectrometry, coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS) offers benefits for the analysis of complex proteomics samples. Advantages include increased dynamic range, increased signal-to-noise, and reduced interference from ions of similar m/ z. FAIMS also separates isomers and positional variants. An alternative, and more established, method of reducing sample complexity is prefractionation by use of strong cation exchange chromatography. Here, we have compared SCX-LC-MS/MS with LC-FAIMS-MS/MS for the identification of peptides and proteins from whole cell lysates from the breast carcinoma SUM52 cell line. Two FAIMS approaches are considered: (1) multiple compensation voltages within a single LC-MS/MS analysis (internal stepping) and (2) repeat LC-MS/MS analyses at different and fixed compensation voltages (external stepping). We also consider the consequence of the fragmentation method (electron transfer dissociation or collision-induced dissociation) on the workflow performance. The external stepping approach resulted in a greater number of protein and peptide identifications than the internal stepping approach for both ETD and CID MS/MS, suggesting that this should be the method of choice for FAIMS proteomics experiments. The overlap in protein identifications from the SCX method and the external FAIMS method was ~25 % for both ETD and CID, and for peptides was less than 20 %. The lack of overlap between FAIMS and SCX highlights the complementarity of the two techniques. Charge state analysis of the peptide assignments showed that the FAIMS approach identified a much greater proportion of triply-charged ions.

  15. Cation Exchange Resins and colonic perforation. What surgeons need to know

    Science.gov (United States)

    Rodríguez-Luna, María Rita; Fernández-Rivera, Enrique; Guarneros-Zárate, Joaquín E.; Tueme-Izaguirre, Jorge; Hernández-Méndez, José Roberto

    2015-01-01

    Introduction Since 1961 the use of Cation Exchange Resins has been the mainstream treatment for chronic hyperkalemia. For the past 25 years different kind of complications derived from its clinical use have been recognized, being the colonic necrosis the most feared and lethal of all. Presentation of case We report a case of a 72-year-old patient with chronic kidney disease, treated with calcium polystyrene sulfonate for hyperkalemia treatment who presented in the emergency department with constipation treated with hypertonic cathartics. With clinical deterioration 48 h later progressed with colonic necrosis requiring urgent laparotomy, sigmoidectomy and open abdomen management with subsequent rectal stump perforation and dead. The histopathology finding: calcium polystyrene sulfonate embedded in the mucosa, consistent with the cause of perforation. Discussion Lillemoe reported the first case series of five uremic patients with colonic perforation associated with the use of SPS in sorbitol in 1987 and in 2009 the FDA removed from the market the SPS containing 70% of sorbitol. The pathophysiologic change of CER goes from mucosal edema, ulcers, pseudomembranes, and the most severe case transmural necrosis. Up to present day, some authors have questioned the use of CER in the setting of lowering serum potassium. Despite its worldwide use in hyperkalemia settings, multiple studies have not demonstrated a significant potassium excretion by CER. Conclusion Despite the low incidence of colonic complication and lethal colonic necrosis associated with the CER clinical use, the general surgeon needs a high index of suspicion when dealing with patients treated with CER and abdominal pain. PMID:26439420

  16. A new cation-exchange method for accurate field speciation of hexavalent chromium

    Science.gov (United States)

    Ball, J.W.; McCleskey, R.B.

    2003-01-01

    A new method for field speciation of Cr(VI) has been developed to meet present stringent regulatory standards and to overcome the limitations of existing methods. The method consists of passing a water sample through strong acid cation-exchange resin at the field site, where Cr(III) is retained while Cr(VI) passes into the effluent and is preserved for later determination. The method is simple, rapid, portable, and accurate, and makes use of readily available, inexpensive materials. Cr(VI) concentrations are determined later in the laboratory using any elemental analysis instrument sufficiently sensitive to measure the Cr(VI) concentrations of interest. The new method allows measurement of Cr(VI) concentrations as low as 0.05 ??g 1-1, storage of samples for at least several weeks prior to analysis, and use of readily available analytical instrumentation. Cr(VI) can be separated from Cr(III) between pH 2 and 11 at Cr(III)/Cr(VI) concentration ratios as high as 1000. The new method has demonstrated excellent comparability with two commonly used methods, the Hach Company direct colorimetric method and USEPA method 218.6. The new method is superior to the Hach direct colorimetric method owing to its relative sensitivity and simplicity. The new method is superior to USEPA method 218.6 in the presence of Fe(II) concentrations up to 1 mg 1-1 and Fe(III) concentrations up to 10 mg 1-1. Time stability of preserved samples is a significant advantage over the 24-h time constraint specified for USEPA method 218.6.

  17. Enhanced capacity and stability for the separation of cesium in electrically switched ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Tawfic, A.F.; Dickson, S.E.; Kim, Y. [McMaster University, Hamilton, ON (Canada); Mekky, W. [AMEC NSS, Power and Process America, Toronto (Canada)

    2015-03-15

    Electrically switched ion exchange (ESIX) can be used to separate ionic contaminants from industrial wastewater, including that generated by the nuclear industry. The ESIX method involves sequential application of reduction and oxidation potentials to an ion exchange film to induce the respective loading and unloading of cesium. This technology is superior to conventional methods (e.g electrodialysis reversal or reverse osmosis) as it requires very little energy for ionic separation. In previous studies, ESIX films have demonstrated relatively low ion exchange capacities and limited film stabilities over repeated potential applications. In this study, the methodology for the deposition of electro-active films (nickel hexacyanoferrate) on nickel electrodes was modified to improve the ion exchange capacity for cesium removal using ESIX. Cyclic voltammetry was used to investigate the ion exchange capacity and stability. Scanning electron microscopy (SEM) was used to characterize the modified film surfaces. Additionally, the films were examined for the separation of cesium ions. This modified film preparation technique enhanced the ion exchange capacity and improves the film stability compared to previous methods for the deposition of ESIX films. (authors)

  18. Magnetic graphene - polystyrene sulfonic acid nano composite: A dispersive cation exchange sorbent for the enrichment of aminoalcohols and ethanolamines from environmental aqueous samples.

    Science.gov (United States)

    Chinthakindi, Sridhar; Purohit, Ajay; Singh, Varoon; Tak, Vijay; Dubey, D K; Pardasani, Deepak

    2015-12-04

    Present study aimed at graphene surface modification to achieve selective analyte binding in dispersive solid phase extraction. Magnetic graphene - polystyrene sulfonic acid (MG-PSS) cation exchange nano-composite was prepared by non-covalent wrapping method. Composite was characterized by FT-IR and zeta potential. Material exhibited good dispersion in water and high exchange capacity of 1.97±0.16mMg(-1). Prepared nano-sorbent was then exploited for the cation exchange extraction and gas chromatography mass spectrometric analysis of Chemical Weapons Convention relevant aminoalcohols and ethanolamines from aqueous samples. Extraction parameters such as sorbent amount, extraction time, desorption conditions and sample pH were optimized and effect of common matrix interferences such as polyethylene glycol and metal salts was also studied. Three milligram of sorbent per mL of sample with 20min of extraction time at room temperature afforded 70-81% recoveries of the selected analytes spiked at concentration level of 1μgmL(-1). Method showed good linearity in the studied range with r(2)≥0.993. The limits of detection and limits of quantification ranged from 23 to 54ngmL(-1) and 72 to 147ngmL(-1), respectively. The relative standard deviation for intra- and inter-day precision ranged from 4.6 to 10.2% and 7.4 to 14.8% respectively. Applicability of the method to different environmental samples as well as the proficiency tests conducted by the Organization for the Prohibition of Chemical Weapons (OPCW) was also ascertained.

  19. Indirect UV detection-ion-exclusion/cation-exchange chromatography of common inorganic ions with sulfosalicylic acid eluent.

    Science.gov (United States)

    Kozaki, Daisuke; Mori, Masanobu; Nakatani, Nobutake; Arai, Kaori; Masuno, Tomoe; Koseki, Masakazu; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2013-01-01

    Herein, we describe indirect UV detection-ion-exclusion/cation-exchange chromatography (IEC/CEC) on a weakly acidic cation-exchange resin in the H(+)-form (TSKgel Super IC-A/C) using sulfosalicylic acid as the eluent. The goal of the study was to characterize the peaks detected by UV detector. The peak directions of analyte ions in UV at 315 nm were negative because the molar absorbance coefficients of analyte anions and cations were lower than that of the sulfosalicylic acid eluent. Good chromatographic resolution and high signal-to-noise ratios of analyte ions were obtained for the separations performed using 1.1 mM sulfosalicylic acid and 1.5 mM 18-crown-6 as the eluent. The relative standard deviations (RSDs) of the peak areas ranged from 0.6 to 4.9%. Lower detection limits of the analytes were achieved using indirect UV detection at 315 nm (0.23 - 0.98 μM) than those obtained with conductometric detection (CD) (0.61 - 2.1 μM) under the optimized elution conditions. The calibration curves were linear in the range from 0.01 to 1.0 mM except for Cl(-), which was from 0.02 to 2.0 mM. The present method was successfully applied to determine common inorganic ions in a pond water sample.

  20. An Investigation into the Effect of Cation-exchange on the Adsorption Performance of Indium-based Sodalite-ZMOF

    KAUST Repository

    Samin, Umer A.

    2016-04-13

    There is a pressing need for advanced solid-state materials that can be implemented in industrial gas separation processes to achieve separations with a significantly reduced energy input compared to what is typically required from current technologies. Although certain porous materials like zeolites bear some commercial significance for gas separation; their inherent lack of tunability limits the extent to which these materials may be exploited in industry. Zeolite-like Metal-Organic Frameworks (ZMOFs) are a sub-class of Metal-Organic Framework materials (MOFs) that show a structural semblance to zeolites while possessing the tunability advantages of MOF materials. ZMOFs which are topologically similar to certain zeolites can be functionalised and tuned in numerous ways to improve their gas separation properties. In this work, indium-based sod-ZMOF was tuned by cation-exchange and then characterised by different experimental tools such as single-crystal x-ray diffraction, elemental analysis and gas adsorption. It was found that various parameters like the choice of cation, the concentration of salt solution and the choice of solvent had a significant bearing on the cation-exchange of sod-ZMOF and its subsequent adsorption properties.

  1. Synthesis of cation-exchanged laponite suspensions by laser ablation of microsized-metal particles in liquid

    Science.gov (United States)

    Phuoc, Tran X.; Chen, Ruey-Hung

    2011-03-01

    Laser ablation in the liquid technique has been used to synthesize cation-exchanged laponite suspensions. In summary, laser ablation of the microsize-metal powder (Co, Al, and Cu) dispersed in an aqueous solution containing deionized water laponite crystals was carried out using laser beam generated by a single-mode, Q-switched Nd-Yag laser operating at 532 nm with a pulse duration of 5.5 ns and 10 Hz repetition rate. Laser fluence was 0.265 J/cm 2 for all tests. For all samples, the mass fraction of laponite was 1%. General observations of the prepared samples indicated that an aqueous suspension of 1 wt% laponite retained its free flowing liquid phase characteristics even after aging for several weeks. When bivalent cationic metals (Cu, Co, Al) were ablated in it for about 1 h, even with a small amount of the metal (0.025% and 0.050%) were generated, the suspension became highly viscous and behaved as a shear-thinning and thixotropic material. That is, the suspension gelled strongly when it was allowed to rest. The gels, however, could easily be reverted to a low viscosity liquid with simple shaking. Information from TEM and XRD analysis indicated that such a sol-gel transformation might be due to the charge exchange between the cationic species produced during the laser ablation and the sodium ions in the interlayers of the clay sheets.

  2. Ion exchange equilibrium constants

    CERN Document Server

    Marcus, Y

    2013-01-01

    Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and

  3. Alkali metal cation doping of metal-organic framework for enhancing carbon dioxide adsorption capacity

    Institute of Scientific and Technical Information of China (English)

    Yan Cao; Yunxia Zhao; Fujiao Song; Qin Zhong

    2014-01-01

    Metal-organic frameworks (MOFs) have attracted much attention as adsorbents for the separation of CO2 from flue gas or natural gas. Here, a typical metal-organic framework HKUST-1(also named Cu-BTC or MOF-199) was chemically reduced by doping it with alkali metals (Li, Na and K) and they were further used to investigate their CO2 adsorption capacities. The structural information, surface chemistry and thermal behavior of the prepared adsorbent samples were characterized by X-ray powder diffraction (XRD), thermo-gravimetric analysis (TGA) and nitrogen adsorption-desorption isotherm analysis. The results showed that the CO2 storage capacity of HKUST-1 doped with moderate quantities of Li+, Na+ and K+, individually, was greater than that of unmodified HKUST-1. The highest CO2 adsorption uptake of 8.64 mmol/g was obtained with 1K-HKUST-1, and it was ca. 11%increase in adsorption capacity at 298 K and 18 bar as compared with HKUST-1. Moreover, adsorption tests showed that HKUST-1 and 1K-HKUST-1 displayed much higher adsorption capacities of CO2 than those of N2. Finally, the adsorption/desorption cycle experiment revealed that the adsorption performance of 1K-HKUST-1 was fairly stable, without obvious deterioration in the adsorption capacity of CO2 after 10 cycles.

  4. Consistent effects of canopy vs. understory nitrogen addition on the soil exchangeable cations and microbial community in two contrasting forests.

    Science.gov (United States)

    Shi, Leilei; Zhang, Hongzhi; Liu, Tao; Zhang, Weixin; Shao, Yuanhu; Ha, Denglong; Li, Yuanqiu; Zhang, Chuangmao; Cai, Xi-an; Rao, Xingquan; Lin, Yongbiao; Zhou, Lixia; Zhao, Ping; Ye, Qing; Zou, Xiaoming; Fu, Shenglei

    2016-05-15

    Anthropogenic N deposition has been well documented to cause substantial impacts on the chemical and biological properties of forest soils. In most studies, however, atmospheric N deposition has been simulated by directly adding N to the forest floor. Such studies thus ignored the potentially significant effect of some key processes occurring in forest canopy (i.e., nitrogen retention) and may therefore have incorrectly assessed the effects of N deposition on soils. Here, we conducted an experiment that included both understory addition of N (UAN) and canopy addition of N (CAN) in two contrasting forests (temperate deciduous forest vs. subtropical evergreen forest). The goal was to determine whether the effects on soil exchangeable cations and microbial biomass differed between CAN and UAN. We found that N addition reduced pH, BS (base saturation) and exchangeable Ca and increased exchangeable Al significantly only at the temperate JGS site, and reduced the biomass of most soil microbial groups only at the subtropical SMT site. Except for soil exchangeable Mn, however, effects on soil chemical properties and soil microbial community did not significantly differ between CAN and UAN. Although biotic and abiotic soil characteristics differ significantly and the responses of both soil exchangeable cations and microbial biomass were different between the two study sites, we found no significant interactive effects between study site and N treatment approach on almost all soil properties involved in this study. In addition, N addition rate (25 vs. 50 kg N ha(-1) yr(-1)) did not show different effects on soil properties under both N addition approaches. These findings did not support previous prediction which expected that, by bypassing canopy effects (i.e., canopy retention and foliage fertilization), understory addition of N would overestimate the effects of N deposition on forest soil properties, at least for short time scale.

  5. Ion chromatographic separation of inorganic ions using a combination of hydrophilic interaction chromatographic column and cation-exchange resin column.

    Science.gov (United States)

    Arai, Kaori; Mori, Masanobu; Hironaga, Takahiro; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2012-04-01

    A combination of hydrophilic interaction chromatographic (HILIC) column and a weakly acidic cation-exchange resin (WCX) column was used for simultaneous separation of inorganic anions and cations by ion chromatography (IC). Firstly, the capability of HILIC column for the separation of analyte ions was evaluated under acidic eluent conditions. The columns used were SeQuant ZIC-HILIC (ZIC-HILIC) with a sulfobetaine-zwitterion stationary phase (ZIC-HILIC) and Acclaim HILIC-10 with a diol stationary phase (HILIC-10). When using tartaric acid as the eluent, the HILIC columns indicated strong retentions for anions, based on ion-pair interaction. Especially, HILIC-10 could strongly retain anions compared with ZIC-HILIC. The selectivity for analyte anions of HILIC-10 with 5 mmol/L tartaric acid eluent was in the order of I(-) > NO3(-) > Br(-) > Cl(-) > H2PO4(-). However, since HILIC-10 could not separate analyte cations, a WCX column (TSKgel Super IC-A/C) was connected after the HILIC column in series. The combination column system of HILIC and WCX columns could successfully separate ten ions (Na+, NH4+, K+, Mg2+, Ca2+, H2PO4(-), Cl(-), Br(-), NO3(-) and I(-)) with elution of 4 mmol/L tartaric acid plus 8 mmol/L 18-crown-6. The relative standard deviations (RSDs) of analyte ions by the system were in the ranges of 0.02% - 0.05% in retention times and 0.18% - 5.3% in peak areas through three-time successive injections. The limits of detection at signal-to-noise ratio of 3 were 0.24 - 0.30 micromol/L for the cations and 0.31 - 1.2 micromol/L for the anions. This system was applied for the simultaneous determination of the cations and the anions in a vegetable juice sample with satisfactory results.

  6. Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

    Directory of Open Access Journals (Sweden)

    V. Romero

    2012-01-01

    A study of time evolution of the impedance curves measured in the system “IL aqueous solution/Nafion-112 membrane/IL aqueous solution” was also performed. This study allows us monitoring the electrical changes associated to the IL-cation incorporation in both the membrane and the membrane/IL solution interface, and it provides supplementary information on the characteristic of the Nafion/DTA+ hybrid material. Moreover, the results also show the significant effect of water on the electrical resistance of the Nafion-112/IL-cation-modified membrane.

  7. Highly Emissive Divalent-Ion-Doped Colloidal CsPb1–xMxBr3 Perovskite Nanocrystals through Cation Exchange

    Science.gov (United States)

    2017-01-01

    Colloidal CsPbX3 (X = Br, Cl, and I) perovskite nanocrystals (NCs) have emerged as promising phosphors and solar cell materials due to their remarkable optoelectronic properties. These properties can be tailored by not only controlling the size and shape of the NCs but also postsynthetic composition tuning through topotactic anion exchange. In contrast, property control by cation exchange is still underdeveloped for colloidal CsPbX3 NCs. Here, we present a method that allows partial cation exchange in colloidal CsPbBr3 NCs, whereby Pb2+ is exchanged for several isovalent cations, resulting in doped CsPb1–xMxBr3 NCs (M= Sn2+, Cd2+, and Zn2+; 0 50%), sharp absorption features, and narrow emission of the parent CsPbBr3 NCs. The blue-shift in the optical spectra is attributed to the lattice contraction that accompanies the Pb2+ for M2+ cation exchange and is observed to scale linearly with the lattice contraction. This work opens up new possibilities to engineer the properties of halide perovskite NCs, which to date are demonstrated to be the only known system where cation and anion exchange reactions can be sequentially combined while preserving the original NC shape, resulting in compositionally diverse perovskite NCs. PMID:28260380

  8. PROPYLENE OLIGOMERIZATION CATALYZED BY HIGHLY ACIDIC CATION EXCHANGE RESIN%强酸性阳离子交换树脂催化丙烯齐聚

    Institute of Scientific and Technical Information of China (English)

    佟春雨; 陈群; 孙富安; 陈亮; 何明阳

    2012-01-01

    A catalyst of cation exchange resin was selected to catalyze propylene oligomerization. The relationship between resin properties and catalytic activities were studied and the optimal reaction conditions of the typical resin LC001 were investigated. The propylene oligomerization was catalyzed by cation resin LC001 with macroporous and high exchange capacity. The once through conversion of propylene kept at about 64.7%, and the selectivity of nonene and dodecene in liquid products were about 58% under the optimized conditions of reaction temperature 150℃, reaction pressure 4.0MPa and the LHSV 1.5h'\\ This catalyst displayed good stability, high activity and simple process. It showed a good prospect in industrial production.%筛选了可用于丙烯齐聚的阳离子交换树脂催化剂,研究了树脂性质与催化性能间的关系,并考察了自制LC001树脂催化丙烯齐聚的工艺条件.结果发现,采用大孔、高交换量的LC001树脂在150℃、4.0MPa、液时空速为1.5h-1条件下反应,丙烯单程转化率达到64.7%,C9和C12烯烃的选择性能达到58%.催化剂性能稳定,催化活性高,工艺流程简单,有很好的工业应用前景.

  9. Selective sorption of lead, cadmium and zinc ions by a polymeric cation exchanger containing nano-Zr(HPO3S)2.

    Science.gov (United States)

    Zhang, Qingrui; Pan, Bingcai; Pan, Bingjun; Zhang, Weiming; Jia, Kun; Zhang, Quanxing

    2008-06-01

    A novel polymeric hybrid sorbent, namely ZrPS-001, was fabricated for enhanced sorption of heavy metal ions by impregnating Zr(HPO3S)2 (i.e., ZrPS) nanoparticles within a porous polymeric cation exchanger D-001. The immobilized negatively charged groups bound to the polymeric matrix D-001 would result in preconcentration and permeation enhancement of target metal ions prior to sequestration, and ZrPS nanoparticles are expected to sequester heavy metals selectively through an ion-exchange process. Highly effective sequestration of lead, cadmium, and zinc ions from aqueous solution can be achieved by ZrPS-001 even in the presence of competing calcium ion at concentration several orders of magnitude greater than the target species. The exhausted ZrPS-001 beads are amenable to regeneration with 6 M HCI solution for repeated use without any significant capacity loss. Fixed-bed column treatment of simulated waters containing heavy metals at high or trace levels was also performed. The content of heavy metals in treated effluent approached or met the WHO drinking water standard.

  10. Uncertainties of Gaseous Oxidized Mercury Measurements Using KCl-Coated Denuders, Cation-Exchange Membranes, and Nylon Membranes: Humidity Influences.

    Science.gov (United States)

    Huang, Jiaoyan; Gustin, Mae Sexauer

    2015-05-19

    Quantifying the concentration of gaseous oxidized mercury (GOM) and identifying the chemical compounds in the atmosphere are important for developing accurate local, regional, and global biogeochemical cycles. The major hypothesis driving this work was that relative humidity affects collection of GOM on KCl-coated denuders and nylon membranes, both currently being applied to measure GOM. Using a laboratory manifold system and ambient air, GOM capture efficiency on 3 different collection surfaces, including KCl-coated denuders, nylon membranes, and cation-exchange membranes, was investigated at relative humidity ranging from 25 to 75%. Recovery of permeated HgBr2 on KCl-coated denuders declined by 4-60% during spikes of relative humidity (25 to 75%). When spikes were turned off GOM recoveries returned to 60 ± 19% of permeated levels. In some cases, KCl-coated denuders were gradually passivated over time after additional humidity was applied. In this study, GOM recovery on nylon membranes decreased with high humidity and ozone concentrations. However, additional humidity enhanced GOM recovery on cation-exchange membranes. In addition, reduction and oxidation of elemental mercury during experiments was observed. The findings in this study can help to explain field observations in previous studies.

  11. Comparison of gaseous oxidized Hg measured by KCl-coated denuders, and nylon and cation exchange membranes.

    Science.gov (United States)

    Huang, Jiaoyan; Miller, Matthieu B; Weiss-Penzias, Peter; Gustin, Mae Sexauer

    2013-07-02

    The chemical compounds that make up gaseous oxidized mercury (GOM) in the atmosphere, and the reactions responsible for their formation, are not well understood. The limitations and uncertainties associated with the current method applied to measure these compounds, the KCl-coated denuder, are not known due to lack of calibration and testing. This study systematically compared the uptake of specific GOM compounds by KCl-coated denuders with that collected using nylon and cation exchange membranes in the laboratory and field. In addition, a new method for identifying different GOM compounds using thermal desorption is presented. Different GOM compounds (HgCl2, HgBr2, and HgO) were found to have different affinities for the denuder surface and the denuder underestimated each of these compounds. Membranes measured 1.3 to 3.7 times higher GOM than denuders in laboratory and field experiments. Cation exchange membranes had the highest collection efficiency. Thermodesorption profiles for the release of GOM compounds from the nylon membrane were different for HgO versus HgBr2 and HgCl2. Application of the new field method for collection and identification of GOM compounds demonstrated these vary as a function of location and time of year. Understanding the chemistry of GOM across space and time has important implications for those developing policy regarding this environmental contaminant.

  12. Toward Separating Alpha-lactalbumin and Beta-lactoglobulin Proteins from Whey through Cation-exchange Adsorption

    Science.gov (United States)

    El-Sayed, Mayyada; Chase, Howard

    2009-05-01

    This paper describes the cation-exchange adsorption of the two major whey proteins, alpha-lactalbumin (ALA) and beta-lactoglobulin (BLG) with the purpose of establishing a process for isolating them from cow's milk whey. The single- and two-component adsorption of 1.5 mg/ml ALA and 3 mg/ml BLG to the cation-exchanger SP Sepharose FF at 20° C using 0.1 M acetate buffer of pH 3.7 was studied. Langmuir isotherm parameters were determined for the pure proteins. In two-component systems, BLG breakthrough curve exhibited an overshoot phenomenon that gave evidence for the presence of a competitive adsorption between the two proteins. Complete separation occurred and it was possible to obtain each of the two proteins in a pure form. The process was then applied to a whey concentrate mixture where incomplete separation took place. However, BLG was produced with 95% purity and a recovery of 80%, while ALA showed an 84% recovery with low purity.

  13. Radiometric Determination of Uranium in Natural Waters after Enrichment and Separation by Cation-Exchange and Liquid-Liquid Extraction

    CERN Document Server

    Pashalidis, I

    2003-01-01

    The alpha-radiometric determination of uranium after its pre-concentration from natural water samples using the cation-exchange resin Chelex-100, its selective extraction by tributylphosphate and electrodeposition on stainless steel discs is reported. The validity of the separation procedure and the chemical recoveries were checked by addition of uranium standard solution as well as by tracing with U-232. The average uranium yield was determined to be (97 +- 2) % for the cation-exchange, (95 +- 2) % for the liquid-liquid extraction, and more than 99% for the electrodeposition. Employing high-resolution alpha-spectroscopy, the measured activity of the U-238 and U-234 radioisotopes was found to be of similar magnitude; i.e. ~7 mBq/L and ~35 mBq/L for ground- and seawater samples, respectively. The energy resolution (FWHM) of the alpha-peaks was 22 keV, while the Minimum Detectable Activity (MDA) was estimated to be 1 mBq/L (at the 95% confidence limit).

  14. Cation exchange applications of synthetic tobermorite for the immobilization and solidification of cesium and strontium in cement matrix

    Indian Academy of Sciences (India)

    O P Shrivastava; Rashmi Shrivastava

    2000-12-01

    Immobilization and solidification of hazardous cations like Cs137 and Sr90 are required while handling the radioactive waste of nuclear power plants. Efforts are on to find a fail proof method of safe disposal of nuclear wastes. In this context, various materials like borosilicate glass, zeolites, cements and synthetic rocks have been tried by several workers. This communication deals with the synthesis, characterization, cesium uptake capacity and leaching behaviour of synthetic alumina-substituted calcium silicate hydroxy hydrate, which are close to that obtained for the natural mineral, 11 Å tobermorite. The synthetic mineral show cation selectivity for Cs+ in presence of 500–1000 times concentrated solutions of Na+ , K+ , Mg2+, Ca2+ , Ba2+ and Sr2+. Although the ordinary portland cement (OPC) which is often used in waste management operations alone holds negligible amounts of Cs+ and Sr2+, the addition of alumina-substituted tobermorite to OPC enhances the retention power of cement matrix by drastically lowering the leach rate of cations.

  15. 阳离子树脂净化铂族金属溶液的研究%Purification of Platinum Group Metals Solution by Cation Exchange

    Institute of Scientific and Technical Information of China (English)

    毕向光; 余建民; 杨金富; 贺洪亮; 李权

    2015-01-01

    研究了阳离子交换树脂净化含大量贱金属的铂族金属溶液的工艺条件,结果表明,在pH=1~1.5时001×7阳离子交换树脂吸附贱金属的次序为:Ni>Cu>Co>Fe;Fe、Ni、Co、Cu的穿透容量分别为(g/kg):0.13,1.25,0.42,0.87;饱和容量分别为(g/kg):0.32,6.65,2.33,4.72,合计为14.02 g/kg;贱金属的分离效率主要取决于贵贱金属浓度及交换柱的数量;吸附在树脂上的贱金属极易被6 mol/L HCl洗脱,所有贱金属的最大洗脱均发生在洗脱液体积与床体积之比为1.0/1.7处,当洗脱液体积为床体积的2.0倍时贱金属被完全洗脱。实验结果为离子交换分离贱金属净化铂族金属溶液的工业化应用提供了强有力的理论依据。%The platimum group metals ( PGMs) solution containing a large amount of base metals purified with cation exchange resin had been investigated. The results showed that the adsorption of base metals by 001 × 7 cation ion exchange resin at pH=1~1.5 was in the order of Ni>Cu>Co>Fe. From the tests, the breakthrough capacities ( g/kg) of Fe, Ni, Co and Cu were 0.13, 1.25, 0.42 and 0.87, respectively, while the saturated capacities ( g/kg) were 0.32, 6.65, 2.33 and 4.72, respectively and 14.02 g/kg in total. It is shown that the separation efficiency of the base metals depends largely on the concentrations of the precious and base metals, as well as the number of exchange columns. The base metals absorbed on the resin could be easily eluted by adding HCl solution at the amount of 6 mol/L, with the elution reaching the maximum as the eluent volume and bed volume at the ratio of 1.0/1.7 and completely finished as the eluent volume being 2. 0 times the bed volume. The experimental results can definitely provide a theoretical basis favorably for the industrial application of PGMs solution purified by cation exchange resin.

  16. ANION EXCHANGE CAPACITY OF CHROMATE ON MODIFIED ZEOLITE CLINOPTILOLITE WITH HDTMA-Br AND ITS REGENERATION

    Directory of Open Access Journals (Sweden)

    Widajanti Wibowo

    2011-04-01

    Full Text Available Zeolite Clinoptilolite from Lampung, located in South of Sumatra, had been modified with surfactanthexadecyltrimethylammonium bromide (HDTMA-Br as chromate anion exchanger. Surfactant modified zeolite (SMZClinoptilolite in particle size range of 1.5 - 2.0 mm, which contained 196.7 mmol HDTMA-Br/kg zeolite, was used foranion exchange of chromate at neutral pH. This experiment was conducted in a glass column filled with 5 gram SMZ.The breakthrough chromate exchange capacity was found 1.262 mg/g SMZ, while the total capacity was found 2.107mg/g SMZ. The regeneration of SMZ saturated with chromate was conducted using a mixed solutions of 0.28 MNa2CO3 and 0.5 M NaOH, compared with using a solution of 0.01 M Na2S2O4. The desorption of chromate achieved92% with the mixed solutions of Na2CO3 and NaOH and 90% with the Na2S2O4 solution. The regenerated SMZ withNa2CO3-NaOH solutions was prior washed with HCl solution to remove the carbonate from SMZ, before being used forchromate sorption again. Its breakthrough capacity was reduced to 1.074 mg/g SMZ, and to 0.724 mg/g SMZ whenregenerated with Na2S2O4 solution. These results indicated that regeneration of SMZ affected its exchange capacity foranion chromate. However, it is still could be acceptable, when Na2CO3/NaOH solutions were used for the regenerationof SMZ saturated with anion chromate.

  17. Water quality monitoring system for determination of ionic nutrients by ion-exclusion chromatography with spectrophotometric detection on cation- and anion-exchange resin columns using water eluent.

    Science.gov (United States)

    Kozaki, Daisuke; Nakatani, Nobutake; Mori, Masanobu; Nakagoshi, Nobukazu; Tanaka, Kazuhiko

    2012-07-01

    A unified ion-exclusion chromatography (IEC) system for monitoring anionic and cationic nutrients like NH4+, NO2-, NO3-, phosphate ion, silicate ion and HCO3- was developed and applied to several environmental waters. The IEC system consisted of four IEC methodologies, including the IEC with ultraviolet (UV) form connected with detection at 210 nm for determining NH4+ on anion-exchange separation column in OH anion-exchange UV-conversion column in I- form in tandem, the IEC with UV-detection at 210 nm for determining simultaneously NO3- and NO3- on cation-exchange separation column in H+ form, the IEC with UV-detection at 210 nm for determining HCO3- on cation-exchange separation column in H+ form connected with anion-exchange UV-conversion column in I- form in tandem, and the IEC with visible-detection based on molybdenum-blue reaction for determining simultaneously silicate and phosphate ions on cation-exchange separation column in H+ form. These IEC systems were combined through three manually-driven 6-port column selection valves to select each separation column to determine selectively the ionic nutrients. Using this sequential water quality monitoring system, the analytical performances such as calibration linearity, reproducibility, detection limit and recovery were also tested under the optimized chromatographic conditions. This novel water quality monitoring system has been applied successfully for the determination of the ionic eutrophication components in sub-urban river waters.

  18. Selective cation exchange in the core region of Cu2-xSe/Cu2-xS core/shell nanocrystals.

    Science.gov (United States)

    Miszta, Karol; Gariano, Graziella; Brescia, Rosaria; Marras, Sergio; De Donato, Francesco; Ghosh, Sandeep; De Trizio, Luca; Manna, Liberato

    2015-09-30

    We studied cation exchange (CE) in core/shell Cu2-xSe/Cu2-xS nanorods with two cations, Ag(+) and Hg(2+), which are known to induce rapid exchange within metal chalcogenide nanocrystals (NCs) at room temperature. At the initial stage of the reaction, the guest ions diffused through the Cu2-xS shell and reached the Cu2-xSe core, replacing first Cu(+) ions within the latter region. These experiments prove that CE in copper chalcogenide NCs is facilitated by the high diffusivity of guest cations in the lattice, such that they can probe the whole host structure and identify the preferred regions where to initiate the exchange. For both guest ions, CE is thermodynamically driven as it aims for the formation of the chalcogen phase characterized by the lower solubility under the specific reaction conditions.

  19. Ion chromatographic separation of inorganic ions using a combination of hydrophilic interaction chromatographic column and cation-exchange resin column

    Institute of Scientific and Technical Information of China (English)

    Kaori ARAI; Masanobu MORI; Takahiro HIRONAGA; Hideyuki ITABASHI; Kazuhiko TANAKA

    2012-01-01

    A combination of hydrophilic interaction chromatographic ( HILIC ) column and a weakly acidic cation-exchange resin (WCX) column was used for simultaneous separation of inorganic anions and cations by ion chromatography ( IC ).Firstly,the capability of HILIC column for the separation of analyte ions was evaluated under acidic eluent conditions.The columns used were SeQuant ZIC-HILIC (ZIC-HILIC) with a sulfobetainezwitterion stationary phase (ZIC-HILIC) and Acclaim HILIC-10 with a diol stationary phase (HILIC-10).When using tartaric acid as the eluent,the HILIC columns indicated strong retentions for anions,based on ion-pair interaction.Especially,HILIC-10 could strongly retain anions compared with ZIC-HILIC. The selectivity for analyte anions of HILIC-10 with 5 mmol/L tartaric acid eluent was in the order of I- > NO3- > Br- > Cl- >H2PO4-.However,since HILIC-10 could not separate analyte cations,a WCX column (TSKgel Super IC-A/C) was connected after the HILIC column in series.The combination column system of HILIC and WCX columns could successfully separate ten ions (Na+,NH4+,K+,Mg2+,Ca2+,H2PO4-,Cl-,Br-,NO3- and I-) with elution of 4 mmol/L tartaric acid plus 8 mmol/L 18-crown-6.The relative standard deviations (RSDs) of analyte ions by the system were in the ranges of 0.02% - 0.05% in retention times and 0.18% - 5.3% in peak areas through three-time successive injections.The limits of detection at signal-to-noise ratio of 3 were 0.24 - 0.30 μmol/L for the cations and 0.31 - 1.2 μmol/L for the anions.This system was applied for the simultaneous determination of the cations and the anions in a vegetable juice sample with satisfactory results.

  20. Design of a fixed-bed ion-exchange process for the treatment of rinse waters generated in the galvanization process using Laminaria hyperborea as natural cation exchanger.

    Science.gov (United States)

    Mazur, Luciana P; Pozdniakova, Tatiana A; Mayer, Diego A; Boaventura, Rui A R; Vilar, Vítor J P

    2016-03-01

    In this study, the removal of zinc from galvanization wastewaters was performed in a fixed bed column packed with brown macro-algae Laminaria hyperborea, acting as a natural cation exchanger (resin). The rinse wastewater presents a zinc concentration between 9 and 22 mg/L, a high concentration of light metals (mainly Na and Ca), a high conductivity (0.5-1.5 mS/cm) and a low organic content (DOC = 7-15 mg C/L). The zinc speciation diagram showed that approximately 80% of zinc is in the form of Zn(2+) and ≅20% as ZnSO4, considering the effluent matrix. From all operational conditions tested for zinc uptake (17 treatment of 2.4 m(3)/day of galvanization wastewater, resulting in an estimated reactants cost of 2.44 €/m(3).

  1. Formation of ZnSe/Bi{sub 2}Se{sub 3} QDs by surface cation exchange and high photothermal conversion

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Guozhi; Wang, Peng; Zhang, Yanbang [School of science, Tianjin Chengjian University, Tianjin 300384 (China); Wu, Zengna; Li, Qiang; Yao, Jianghong [Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); Chang, Kai [Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)

    2015-08-15

    Water-dispersed core/shell structure ZnSe/Bi{sub 2}Se{sub 3} quantum dots were synthesized by ultrasonicwave-assisted cation exchange reaction. Only surface Zn ion can be replaced by Bi ion in ZnSe quantum dots, which lead to the ultrathin Bi{sub 2}Se{sub 3} shell layer formed. It is significance to find to change the crystal of QDs due to the acting of ultrasonicwave. Cation exchange mechanism and excellent photothermal conversion properties are discussed in detail.

  2. Membrane resistance : The effect of salinity gradients over a cation exchange membrane

    NARCIS (Netherlands)

    Galama, A. H.; Vermaas, D. A.; Veerman, J.; Saakes, M.; Rijnaarts, H. H. M.; Post, J. W.; Nijmeijer, K.

    2014-01-01

    Ion exchange membranes (IEMs) are used for selective transport of ions between two solutions. These solutions are often different in concentration or composition. The membrane resistance (R-M) is an important parameter affecting power consumption or power production in electrodialytic processes. In

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

    Science.gov (United States)

    Hosokawa, Hitoshi; Mochida, Tomoyuki

    2015-12-01

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

  4. Perfluorinated carbon-chain copolymers with functional groups and cation exchange membranes based on them: synthesis, structure and properties

    Science.gov (United States)

    Kirsh, Yu E.; Smirnov, S. A.; Popkov, Yu M.; Timashev, Sergei F.

    1990-06-01

    The review is devoted to perfluorinated polymers with sulphonic and carboxylic acid groups and to cation exchange membranes based on them. The synthesis is described of copolymers of tetrafluoroethylene with perfluorovinyl ethers containing functional groups by radical copolymerisation in an organic medium and in aqueous emulsions. Special features of the copolymerisation and approaches to obtaining copolymers with set characteristics are discussed. Data are presented on the structure and physicochemical properties of the polymeric films. Attempts to form membranes from the polymers obtained, the means of strengthening them and methods for chemical modification are described. Data are correlated on the influence of structure and polymer composition and the nature of the functional groups on the electrochemical characteristics of membranes. Special features of the functioning of perfluorinated membranes in the process for making chlorine and alkali by the electrolysis of sodium chloride solution are considered. The bibliography has 104 references.

  5. Ion-exclusion chromatography with the direct UV detection of non-absorbing inorganic cations using an anion-exchange conversion column in the iodide-form.

    Science.gov (United States)

    Mori, Masanobu; Itabashi, Hideyuki; Ikedo, Mikaru; Tanaka, Kazuhiko

    2006-08-15

    An ion-exclusion chromatographic method for the direct UV detection of non-absorbing inorganic cations such as sodium (Na(+)), ammonium (NH(4)(+)) and hydrazine (N(2)H(5)(+)) ions was developed by connecting an anion-exchange column in the I(-)-form after the separation column. For example, NH(4)(+) is converted to a UV-absorbing molecule, NH(4)I, by the anion-exchange column in the I(-)-form after the ion-exclusion separation on anion-exchange column in the OH(-)-form with water eluent. As a result, the direct UV detection of Na(+), NH(4)(+) and N(2)H(5)(+) could be successfully obtained as well as the well-resolved separation. The calibration graphs of the analyte cations detected with UV at 230nm were linear in the range of 0.001-5.0mM. The detection limits at S/N=3 of the cations were below 0.1muM. This method was applied to real water analysis, the determination of NH(4)(+) in river and rain waters, or that of N(2)H(5)(+) in boiler water, with the satisfactory results. This could be applied also to low- or non-absorbing anions such as fluoride or hydrogencarbonate ions by the combination of a weakly acidic cation-exchange resin in the H(+)-form as the separation column and the anion-exchange conversion column.

  6. Common Ion Effects In Zeoponic Substrates: Dissolution And Cation Exchange Variations Due to Additions of Calcite, Dolomite and Wollastonite

    Science.gov (United States)

    Beiersdorfer, R. E.; Ming, D. W.; Galindo, C., Jr.

    2003-01-01

    c1inoptilolite-rich tuff-hydroxyapatite mixture (zeoponic substrate) has the potential to serve as a synthetic soil-additive for plant growth. Essential plant macro-nutrients such as calcium, phosphorous, magnesium, ammonium and potassium are released into solution via dissolution of the hydroxyapatite and cation exchange on zeolite charged sites. Plant growth experiments resulting in low yield for wheat have been attributed to a Ca deficiency caused by a high degree of cation exchange by the zeolite. Batch-equilibration experiments were performed in order to determine if the Ca deficiency can be remedied by the addition of a second Ca-bearing, soluble, mineral such as calcite, dolomite or wollastonite. Variations in the amount of calcite, dolomite or wollastonite resulted in systematic changes in the concentrations of Ca and P. The addition of calcite, dolomite or wollastonite to the zeoponic substrate resulted in an exponential decrease in the phosphorous concentration in solution. The exponential rate of decay was greatest for calcite (5.60 wt. % -I), intermediate for wollastonite (2.85 wt.% -I) and least for dolomite (1.58 wt.% -I). Additions of the three minerals resulted in linear increases in the calcium concentration in solution. The rate of increase was greatest for calcite (3.64), intermediate for wollastonite (2.41) and least for dolomite (0.61). The observed changes in P and Ca concentration are consistent with the solubilities of calcite, dolomite and wollastonite and with changes expected from a common ion effect with Ca. Keywords: zeolite, zeoponics, common-ion effect, clinoptilolite, hydroxyapatite

  7. On-line coupling of an ion chromatograph to the ICP-MS: Separations with a cation exchange chromatography column

    Energy Technology Data Exchange (ETDEWEB)

    Roellin, Stefan [Studsvik Nuclear AB, Nykoeping (Sweden)

    1999-12-01

    An ion chromatography system was coupled on-line to the ICP-MS. All separations were made with a cation exchange chromatography column. Fundamental laws about elution parameters affecting individual retention times and elution forms are explained by applying a proper ion exchange mechanism for the isocratic elution (separations with constant eluent concentration) of mono-, di-, tri-, and tetravalent cations and the actinide species MO{sub 2}{sup +} and MO{sub 2}{sup 2+}. A separation method with two eluents has been investigated to separate mono- from divalent ions in order to separate isobaric overlaps of Rb/Sr and Cs/Ba. The ions normally formed by actinides in aqueous solutions in the oxidation states III to VI are M{sup 3+}, M{sup 4+}, MO{sub 2}{sup +} and MO{sub 2}{sup 2+} respectively. Elution parameters were investigated to separate all four actinide species from each other in order to separate isobaric overlaps of the actinides Np, Pu, U and Am. A major question of concern over the possible release of actinides to the environment is the speciation of actinides within their four possible oxidation states. To check the possibility of speciation analysis with ion chromatography, a separation method was investigated to separate U{sup 4+} and UO{sub 2}{sup 2+} without changing the redox species composition during the separation. First results of Pu speciation analysis showed that Pu could be eluted as three different species. Pu(VI) was always eluting at the same time as Np(V). This was surprising as Pu(VI) is expected to have the same chemical characteristics as U(VI) and thus was expected to elute at the same time as U(VI)

  8. Controlling electron beam-induced structure modifications and cation exchange in cadmium sulfide–copper sulfide heterostructured nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Haimei [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Sadtler, Bryce; Habenicht, Carsten [Department of Chemistry, University of California, Berkeley, CA 94720 (United States); Freitag, Bert [FEI Company, P.O. Box 80066, KA 5600 Eindhoven (Netherlands); Alivisatos, A. Paul [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Department of Chemistry, University of California, Berkeley, CA 94720 (United States); Kisielowski, Christian, E-mail: CFKisielowski@lbl.gov [National Center for Electron Microcopy, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Joint Center for Artificial Photosynthesis, Berkeley, CA 94720 (United States)

    2013-11-15

    The atomic structure and interfaces of CdS/Cu{sub 2}S heterostructured nanorods are investigated with the aberration-corrected TEAM 0.5 electron microscope operated at 80 kV and 300 kV applying in-line holography and complementary techniques. Cu{sub 2}S exhibits a low-chalcocite structure in pristine CdS/Cu{sub 2}S nanorods. Under electron beam irradiation the Cu{sub 2}S phase transforms into a high-chalcocite phase while the CdS phase maintains its wurtzite structure. Time-resolved experiments reveal that Cu{sup +}–Cd{sup 2+} cation exchange at the CdS/Cu{sub 2}S interfaces is stimulated by the electron beam and proceeds within an undisturbed and coherent sulfur sub-lattice. A variation of the electron beam current provides an efficient way to control and exploit such irreversible solid-state chemical processes that provide unique information about system dynamics at the atomic scale. Specifically, we show that the electron beam-induced copper–cadmium exchange is site specific and anisotropic. A resulting displacement of the CdS/Cu{sub 2}S interfaces caused by beam-induced cation interdiffusion equals within a factor of 3–10 previously reported Cu diffusion length measurements in heterostructured CdS/Cu{sub 2}S thin film solar cells with an activation energy of 0.96 eV. - Highlights: • Heterostructured nanorods were investigated at atomic resolution showing that they are free of extended defects. • Beam–sample interactions are controlled by current and voltage variations to provide pristine crystal structures. • Beam-induced migration of heterointerfaces are measured time-resolved and compared with Cu diffusion coefficients. • Beam–sample interaction overwrite possible signal improvements that can be expected by sample cooling.

  9. Physical characterization of the state of motion of the phenalenyl spin probe in cation-exchanged faujasite zeolite supercages with pulsed EPR

    Science.gov (United States)

    Doetschman, D. C.; Dwyer, D. W.; Fox, J. D.; Frederick, C. K.; Scull, S.; Thomas, G. D.; Utterback, S. G.; Wei, J.

    1994-08-01

    The molecular motion of the phenalenyl (PNL) spin probe in the supercages of cation-exchanged X and Y zeolites (faujasites) has been physically characterized by pulsed and continuous wave (CW) electron paramagnetic resonance (EPR). Both X and Y zeolites, whose cation sites were exchanged with the alkali metal ions, Li +, Na +, K +, Rb + and Cs + were examined. There is a good correspondence between the temperature dependences of the PNL electron spin phase memory time and the CW EPR spectra. Both display evidence of a thermal activation from a stationary, non-rotating molecular state to a low-temperature state of in-plane rotation (Das et al., Chem Phys. 143 (1990) 253). The rate of in-plane rotation is an activated process, with E* | / R=1289 |+- 35 K and 1462 ± 47 K in NaX and KX zeolites, respectively. The rotation appears to be about an axis along which the half-filled, non-bonding π orbital interacts with the exchanged cation in the supercage. Both CW and pulsed EPR also show a higher temperature activation from the in-plane rotating state to an effectively isoptropic state of rotation of PNL in which the PNL-cation bond is thought to be broken, with E* ⊥ / R=2050 ± 110 K, 1956 ± 46K, 1335 ± 97 K in LiX, NaX and KX zeolites, respectively. The strength of the PNL-cation bonding decreases with increasing cation atomic number as indicated by E* ⊥ and the peripheral repulsion (crowding) of PNL increases with cation size as indicated E* |. There are qualitative indications that the binding of PNL to the cations in the Y zeolite is stronger than in the X zeolite.

  10. Structure and resistance of concentration polar layer on cation exchange membrane-solution interface

    Institute of Scientific and Technical Information of China (English)

    SANG Shang-bin; HUANG Ke-long; LI Xiao-gang; WANG Xian

    2006-01-01

    Membrane/solution interface consists of a neutral concentration polar layer(CPL) and a charge layer(CL) under external electrical field, and the neutral CPL can be neglected under high frequency AC electrical field. The relationship of CL thickness e with electrolyte concentration C and fixed ion exchange sites density σ in membrane surface layer can be expressed as e=σ/C.According to this model, the thickness of the CL on Nafion1135 membrane/solution interface(ec) was calculated under different membrane surface charge quantity Q and variable electrolyte concentration C. The membrane/solution interface CL thickness(em) is obviously related with the membrane properties, and decreases dramatically in a higher electrolyte concentration, em values are 76.3nm and 110.3 nm respectively for Nafion1135 and PE01 ion exchange membrane in 0.05 mol/L H2SO4 solution, and em values for both membrane tend to 2 nm in 2 mol/L H2SO4 solution. For Nafion1135 membrane, the comparison of ec and em gives the result that CL thickness em obtained by resistance measurement fits well with the calculated CPL thickness ec while proton in CL transferred to membrane surface is 14.56 × l0-10 mol, which corresponds to the fixed exchange group number in a surface layer with a thickness τ=2 nm for Nafion1135 membrane.

  11. Double sequential modifications of composite cryogel beds for enhanced ion-exchange capacity of protein.

    Science.gov (United States)

    Wang, Chuan; Sun, Yan

    2013-09-13

    Composite cryogel monoliths based on poly(2-hydroxyethylmethacrylate) (pHEMA) were fabricated by incorporating polymeric resin particles. The monoliths were sequentially modified by polyethylenimine (PEI) and diethylaminoethyl (DEAE). The novel composite material had rough pore walls and extended anion-exchange tentacles, which provided more binding sites for protein molecules. The dynamic adsorption capacity of bovine serum albumin (BSA) on the novel cryogel bed reached 11.2mg/mL bed volume at a flow velocity of 8cm/min, which was about 1.5-4.6 times higher than the cryogel beds obtained by single modifications. The capacity value was also much higher than the BSA capacities of cryogel beds reported in literature (1-6mg/mL). The capacity decreased only slightly with increasing flow rate from 0.6 to 12cm/min. The height equivalent to a theoretical plate of the composite beds was in the range 2-2.5mm, changed indistinctively in a flow rate range 0.6-18cm/min. Hence, the work has proved that the double-modification strategy was promising for enhancing protein adsorption capacity of cryogel monolith for high-speed protein chromatography.

  12. Solution-membrane equilibrium at metal-deposited cation-exchange membranes: Chronopotentiometric characterization of metal-modified membranes

    Energy Technology Data Exchange (ETDEWEB)

    Shahi, V.K.; Prakash, R.; Ramachandraiah, G.; Rangarajan, R. [Central Salt and Marine Chemical Research Inst., Bhavnagar (India); Vasudevan, D. [Central Electrochemical Research Inst., Karaikudi (India)

    1999-08-01

    Ion-exchange membranes such as Nafion with suitable metal catalysts entrapped in the body have been found applications in fuel cells, water electrolysis, and also electroorganic synthesis. Copper- and lead-deposited interpolymer cationic membranes have been prepared by electroless plating by an ion-exchange method and characterized by chronopotentiometry and cyclic voltammetry. The parameters such as transition time ({tau}), I{tau}{sup 1/2}, the potential drop (E{sub 0}) across these membranes immediately after the application of constant current (I), and the height of the potential jump ({Delta}E) across the membrane at {tau} have been measured by chronopotentiometry and compared with those of plain membranes. The approximate percentage of metal coverage and the number of ionic sites masked by the deposited metal in terms of NaCl concentration have been estimated from the differences in I{tau}{sup 1/2} values of plain and metal-deposited membranes. The quantity of metal deposited in a unit area of the membrane surface was measured by differential pulse polarography. The oxidation and reduction peak potentials corresponding to Cu(0)/Cu(II) and Pb(0)/Pb(II) couples were identified by cyclic voltammetry at pH 2.8 and 4.5 of 0.2 M CH{sub 3}COONa-H{sub 2}SO{sub 4}.

  13. Comparing the short and long term stability of biodegradable, ceramic and cation exchange membranes in microbial fuel cells.

    Science.gov (United States)

    Winfield, Jonathan; Chambers, Lily D; Rossiter, Jonathan; Ieropoulos, Ioannis

    2013-11-01

    The long and short-term stability of two porous dependent ion exchange materials; starch-based compostable bags (BioBag) and ceramic, were compared to commercially available cation exchange membrane (CEM) in microbial fuel cells. Using bi-directional polarisation methods, CEM exhibited power overshoot during the forward sweep followed by significant power decline over the reverse sweep (38%). The porous membranes displayed no power overshoot with comparably smaller drops in power during the reverse sweep (ceramic 8%, BioBag 5.5%). The total internal resistance at maximum power increased by 64% for CEM compared to 4% (ceramic) and 6% (BioBag). Under fixed external resistive loads, CEM exhibited steeper pH reductions than the porous membranes. Despite its limited lifetime, the BioBag proved an efficient material for a stable microbial environment until failing after 8 months, due to natural degradation. These findings highlight porous separators as ideal candidates for advancing MFC technology in terms of cost and operation stability.

  14. Solvent and irradiation doses effects on the ion exchange capacity of sulfonated styrene grafted PVDF

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Henrique P.; Parra, Duclerc F.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Polymers exhibiting ion exchange capacity are studied for many years due to their application in several fields, such as membranes for proton exchange fuel cells, filtration membranes, heavy ions recovery and artificial muscles and sensors. Radiation induced grafting followed by sulfonation is a well-known way to obtain ion exchange polymers. Fluorinated polymers are frequently used as polymeric matrix for grafting due to their excellent physicochemical properties. Radiation induced grafting of styrene into poly (vinylidene fluoride) (PVDF) by simultaneous method in 1:1 styrene/toluene or styrene/N,N-dimethylformamide solutions was studied. Irradiations were performed under nitrogen atmosphere, room temperature and at doses of 5, 10 and 20 kGy with dose rate of 5 kGy.h{sup -1} from a {sup 60}Co gamma source. After washing, grafted materials were sulfonated in 10% chlorosulfonic acid/1,2-dichloroethane solutions for 4 h at room temperature. Characterization shows that increasing irradiation dose corresponds to increases in the grafting yield (GY %) gravimetrically calculated and these different solvents shows different grafting behaviors. Toluene allows no more than 3 % of grafting while DMF allows up to 55 % of grafting in the same condition. Grafting in toluene solution occurs on the surface and in DMF solution it occurs in the bulk, as confirmed by SEM. Both irradiation doses and solvent used have direct effects in the ion exchange capacities (calculated after titrations). FT-IR spectra exhibit new peaks after grafting and after sulfonation, attributed to grafted monomer and sulfonic groups attached to the styrene. DSC shows differences in thermal behavior of the polymer before and after each step. (author)

  15. Simultaneous determinations of Cr(VI) and Cr(III) by ion-exclusion/cation-exchange chromatography with an unmodified silica-gel column.

    Science.gov (United States)

    Hirata, Shizuko; Kozaki, Daisuke; Sakanishi, Kinya; Nakagoshi, Nobukazu; Tanaka, Kazuhiko

    2010-01-01

    In order to characterize the ion-exclusion and cation-exchange properties of an unmodified silica-gel column, the retention behaviors of Cr(VI) and Cr(III) ions were investigated using a Develosil 30-5 (150 x 4.6 mm i.d.) in the acidic region. Cr(VI) was separated from other anions by an ion-exclusion and ion-adsorption mechanism, and Cr(III) was separated from other cations with a cation-exchange mechanism. When using 2.0 mM oxalic acid (pH 2.6) as an eluent, a good separation of Cr(VI) and Cr(III) was obtained using conductimetric detection in 12 min. The method was successfully applied to the simultaneous determinations of Cr(VI) and Cr(III) added into tap-water and river-water samples.

  16. 2-Acrylamido-2-methyl-1-propanesulfonic Acid Grafted Poly(vinylidene fluoride-co-hexafluoropropylene)-Based Acid-/Oxidative-Resistant Cation Exchange for Membrane Electrolysis.

    Science.gov (United States)

    Pandey, Ravi P; Das, Arindam K; Shahi, Vinod K

    2015-12-30

    For developing acid-/oxidative-resistant aliphatic-polymer-based cation-exchange membrane (CEM), macromolecular modification of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) was carried out by controlled chemical grafting of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). To introduce the unsaturation suitable for chemical grafting, dehydrofluorination of commercially available PVDF-co-HFP was achieved under alkaline medium. Sulfonated copolymer (SCP) was prepared by the free radical copolymerization of dehydofluorinated PVDF-co-HFP (DHPVDF-co-HFP) and AMPS in the presence of free radical initiator. Prepared SCP-based CEMs were analyzed for their morphological characteristics, ion-exchange capacity (IEC), water uptake, conductivity, and stabilities (mechanical, chemical, and thermal) in comparison with state-of-art Nafion117 membrane. High bound water content avoids the membrane dehydration, and most optimal (SCP-1.33) membrane exhibited about ∼2.5-fold high bound water content in comparison with that of Nafion117 membrane. Bunsen reaction of iodine-sulfur (I-S) was successfully performed by direct-contact-mode membrane electrolysis in a two-compartment electrolytic cell using different SCP membranes. High current efficiency (83-99%) confirmed absence of any side reaction and 328.05 kJ mol-H2(-1) energy was required for to produce 1 mol of H2 by electrolytic cell with SCP-1.33 membrane. In spite of low conductivity for reported SCP membrane in comparison with that of Nafion117 membrane, SCP-1.33 membrane was assessed as suitable candidate for electrolysis because of its low-cost nature and excellent stabilities in highly acidic environment may be due to partial fluorinated segments in the membrane structure.

  17. Effect of a cation exchange resin on the uptake of heavy metals by grapevines and other cultivated plants grown in contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Mohr, H.D.

    1982-12-01

    The effect of a cation exchange resin on the growth and heavy metal content of grapevine, sun flower, cress, wheat and Italian rye-grass was investigated in potted vineyard soil, contaminated by Cu-containing (total Cu content of the soil: 628 ppm), or a soil contaminated artificially with 20 ppm Cd. Roots of cress seedlings grown in a vineyard soil mixed with a cation exchange resin were 2.2 times longer than in the untreated soil. Rye-grass was not injured, whereas grapevine, sun flower and wheat showed varying degrees of growth reduction, chlorosis and necrosis when grown in untreated vineyard soil. However, wheat and sunflower grown in vineyard soil containing a cation exchange resin showed no injury and grapevines exhibited markedly reduced symptoms. The Zn, Cu and Cd content of the plants decreased considerably, whereas their Fe and Mn content was not influenced. Grapevine, grown in a calcareous soil contaminated with 20 ppm Cd, contained 447 ppm Cd in the roots and 0,20 ppm Cd in the leaves. The Cd content of the roots declined to 113 ppm, that of the leaves to 0,15 ppm when grown in the contaminated soil containing a cation exchanger.

  18. Effects of disodium cromoglycate on cationic exchange of deoxygenated sickle cells.

    Science.gov (United States)

    Bizumukama, Léonidas; Ferster, Alina; Gulbis, Béatrice; Kumps, Alain; Cotton, Frédéric

    2011-08-31

    In the present work, we explored the way in which cromoglycate, a drug used to treat allergies acts on ion movements in sickle cells. Cells were either slowly deoxygenated by overnight exposure to nitrogen or acutely deoxygenated by exposure to metabisulfite, a strong reducing agent which induces sickling of red blood sickle cells. Flushing the cells with nitrogen increased the intracellular concentration of Na(+) and decreased the intracellular concentration of K(+) and the sum of the concentrations of the two cations. One hundred nM cromoglycate inhibited the decrease of intracellular K(+) and the increase of intracellular Na(+) induced by deoxygenation (n=17). Metabisulfite (100mM) increased the intracellular concentration of Ca(2+) (measured by Fura Red) (n=15) and the shape of the cells (measured by light scattering) (n=9). One μM cromoglycate partially inhibited these two responses. In conclusion, cromoglycate partially inhibits abnormal K(+) loss, Ca(2+) entry pathways or Ca(2+) channels opened by cell deoxygenation and ensuing membrane modifications and prevents cell sickling.

  19. Disintegration and dissolution of spent radioactive cationic exchange resins using Fenton-like oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Zhong; Xu, Lejin [Collaborative Innovation Center for Advanced Nuclear Energy Technology, INET, Tsinghua University, Beijing 100084 (China); Wang, Jianlong, E-mail: wangjl@tsinghua.edu.cn [Collaborative Innovation Center for Advanced Nuclear Energy Technology, INET, Tsinghua University, Beijing 100084 (China); Beijing Key Laboratory of Radioactive Wastes Treatment, Tsinghua University, Beijing 100084 (China)

    2015-09-15

    Highlights: • The spent radioactive resins could be oxidized by Fenton-like process. • The influencing factors on resin oxidation were evaluated. • Chemical oxygen demand (COD) reduction rate was more than 99%. • SEM and Raman spectrum were used to analyze the resins morphological change. - Abstract: The treatment and disposal of the spent radioactive resins is essential for the sustainable development of the nuclear industry. In this paper, the disintegration and dissolution of spent cationic resins were studied by Fenton-like process. The influencing factors on resin dissolution, such as pH, temperature, type and concentration of catalysts were evaluated. The results showed that the spent resins could be effectively dissolved at pH < 1, [Fe{sup 2+}] = 0.2 M and T = 97 ± 2 °C. Chemical oxygen demand (COD) reduction rate was more than 99%. The scanning electron microscopy and the Raman spectrum were used to observe the morphological changes of the spent resins during the dissolution process. Fenton-like oxidation is an efficient method for the volume reduction and stabilization of the spent resins before further immobilization.

  20. Exchangeable sodium induced changes in yield, water relation and cation composition of fennel (Foeniculum vulgare Mill).

    Science.gov (United States)

    Garg, V K; Singh, P K; Pushpangadan, P

    2005-06-01

    A pot experiment was conducted with the objectives to assess the adaptation potential of fennel crop grown at 10, 20, 25, 35 and 40 ESP (exchangeable sodium percentage) levels. Results showed that the rate of seed germination, plant growth including branching pattern, umbels per plant and 1000 test seed weight were adversely affected by sodic soils. Assuming that fifty percent reduction in seed yield and Na+/K+ ratio in leaf tissue as an index of alkali tolerance revealed that fennel was tolerant up to 25 ESP. The cell sap pH and EC reflected optimum osmoticum maintenance to withstand sodicity stress at this level and beyond this leaf water potential decreased (negatively) more to impede water uptake.

  1. Analysis of statistical thermodynamic model for binary protein adsorption equilibria on cation exchange adsorbent

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiaopeng; SU Xueli; SUN Yan

    2007-01-01

    A study of nonlinear competitive adsorption equilibria of proteins is of fundamental importance in understanding the behavior of preparative chromatographic separation.This work describes the nonlinear binary protein adsorption equilibria on ion exchangers by the statistical thermodynamic (ST) model.The single-component and binary protein adsorption isotherms of bovine hemoglobin (Hb) and bovine serum albumin(BSA)on SP Sepharose FF were determined by batch adsorption experiments in 0.05 mol/L sodium acetate buffer at three pH values(4.5,5.0 and 5.5)and three NaCl concentrations(0.05,0.10 and 0.15 mol/L)at pH 5.0.The ST model was found to depict the effects of pH and ionic strength on the single-component equilibria well,with model parameters depending on the pH and ionic strength.Moreover,the ST model gave acceptable fitting to the binary adsorption data with the fltted singlecomponent model parameters,leading to the estimation of the binary ST model parameter.The effects of pH and ionic strength on the model parameters are reasonably interpreted by the electrostatic and thermodynamic theories.Results demonstrate the availability of the ST model for describing nonlinear competitive protein adsorption equilibria in the presence of two proteins.

  2. Reversible dissociation and ligand-glutathione exchange reaction in binuclear cationic tetranitrosyl iron complex with penicillamine.

    Science.gov (United States)

    Syrtsova, Lidia; Sanina, Natalia; Lyssenko, Konstantin; Kabachkov, Evgeniy; Psikha, Boris; Shkondina, Natal'ja; Pokidova, Olesia; Kotelnikov, Alexander; Aldoshin, Sergey

    2014-01-01

    This paper describes a comparative study of the decomposition of two nitrosyl iron complexes (NICs) with penicillamine thiolic ligands [Fe2(SC5H11NO2)2(NO)4]SO4 ·5H2O (I) and glutathione- (GSH-) ligands [Fe2(SC10H17N3O6)2(NO)4]SO4 ·2H2O (II), which spontaneously evolve to NO in aqueous medium. NO formation was measured by a sensor electrode and by spectrophotometric methods by measuring the formation of a hemoglobin- (Hb-) NO complex. The NO evolution reaction rate from (I)  k 1 = (4.6 ± 0.1)·10(-3) s(-1) and the elimination rate constant of the penicillamine ligand k 2 = (1.8 ± 0.2)·10(-3) s(-1) at 25°C in 0.05 M phosphate buffer,  pH 7.0, was calculated using kinetic modeling based on the experimental data. Both reactions are reversible. Spectrophotometry and mass-spectrometry methods have firmly shown that the penicillamine ligand is exchanged for GS(-) during decomposition of 1.5·10(-4) M (I) in the presence of 10(-3) M GSH, with 76% yield in 24 h. As has been established, such behaviour is caused by the resistance of (II) to decomposition due to the higher affinity of iron to GSH in the complex. The discovered reaction may impede S-glutathionylation of the essential enzyme systems in the presence of (I) and is important for metabolism of NIC, connected with its antitumor activity.

  3. Modification of polyamide-CdS-CdSe composite material films with Ag using a cation–cation exchange reaction

    Energy Technology Data Exchange (ETDEWEB)

    Krylova, V.; Žalenkienė, S.; Dukstienė, N. [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu st. 19, LT-50254, Kaunas (Lithuania); Baltrusaitis, J., E-mail: job314@lehigh.edu [Department of Chemical and Biomolecular Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States)

    2015-10-01

    Highlights: • We investigated deposition of a mixed CdSe-CdS-Ag{sub 2}Se-Ag{sub 2}S on polyamide. • A single chalcogen precursor – K{sub 2}SeS{sub 2}O{sub 6} – was used. • AAS showed five- to ten-fold excess of chalcogens diffused into PA. • Addition of AgNO{sub 3} resulted in subsurface Ag{sub 2}Se–Ag{sub 2}S formation. - Abstract: Thin mixed CdSe-CdS-Ag{sub 2}Se-Ag{sub 2}S films were deposited on a polyamide 6 (PA) surface by successfully using a cation-exchange reaction between Cd{sup 2+} and Ag{sup +} to convert CdSe-CdS into Ag{sub 2}Se-Ag{sub 2}S. These were deposited using a K{sub 2}SeS{sub 2}O{sub 6} precursor solution at 60 °C followed by cadmium acetate (Cd(CH{sub 3}COO){sub 2}). An aqueous AgNO{sub 3} solution was used as the Ag source. XRD patterns showed a complex PA-Cd-S-Se-Ag film crystalline composition with CdS, CdSe, Ag{sub 2}S and Ag{sub 2}Se peaks. Calculated dislocation density ranged within 5–15 × 10{sup 13} lines·m{sup −2} indicating high quality atomic layers. Atomic Absorption Spectroscopy (AAS) showed five- to ten-fold excess of chalcogens to metals in the thin films formed. No chalcogenides were observed on the sample surface during XPS analysis after Ag exchange due to the desorption of CdS and CdSe layers, not diffused into the bulk of the polymer suggesting that silver chalcogenides were located subsurface, as opposed to the outermost layer, likely comprised of Ag{sub 2}O.

  4. Proteomics-based, multivariate random forest method for prediction of protein separation behavior during cation-exchange chromatography.

    Science.gov (United States)

    Swanson, Ryan K; Xu, Ruo; Nettleton, Dan; Glatz, Charles E

    2012-08-01

    The most significant cost of recombinant protein production lies in the optimization of the downstream purification methods, mainly due to a lack of knowledge of the separation behavior of the host cell proteins (HCP). To reduce the effort required for purification process development, this work was aimed at modeling the separation behavior of a complex mixture of proteins in cation-exchange chromatography (CEX). With the emergence of molecular pharming as a viable option for the production of recombinant pharmaceutical proteins, the HCP mixture chosen was an extract of corn germ. Aqueous two phase system (ATPS) partitioning followed by two-dimensional electrophoresis (2DE) provided data on isoelectric point, molecular weight and surface hydrophobicity of the extract and step-elution fractions. A multivariate random forest (MVRF) method was then developed using the three characterization variables to predict the elution pattern of individual corn HCP. The MVRF method achieved an average root mean squared error (RMSE) value of 0.0406 (fraction of protein eluted in each CEX elution step) for all the proteins that were characterized, providing evidence for the effectiveness of both the characterization method and the analysis approach for protein purification applications.

  5. Purification of Monoclonal Antibodies Using a Fiber Based Cation-Exchange Stationary Phase: Parameter Determination and Modeling

    Directory of Open Access Journals (Sweden)

    Jan Schwellenbach

    2016-10-01

    Full Text Available Monoclonal antibodies (mAb currently dominate the market for protein therapeutics. Because chromatography unit operations are critical for the purification of therapeutic proteins, the process integration of novel chromatographic stationary phases, driven by the demand for more economic process schemes, is a field of ongoing research. Within this study it was demonstrated that the description and prediction of mAb purification on a novel fiber based cation-exchange stationary phase can be achieved using a physico-chemical model. All relevant mass-transport phenomena during a bind and elute chromatographic cycle, namely convection, axial dispersion, boundary layer mass-transfer, and the salt dependent binding behavior in the fiber bed were described. This work highlights the combination of model adaption, simulation, and experimental parameter determination through separate measurements, correlations, or geometric considerations, independent from the chromatographic cycle. The salt dependent binding behavior of a purified mAb was determined by the measurement of adsorption isotherms using batch adsorption experiments. Utilizing a combination of size exclusion and protein A chromatography as analytic techniques, this approach can be extended to a cell culture broth, describing the salt dependent binding behavior of multiple components. Model testing and validation was performed with experimental bind and elute cycles using purified mAb as well as a clarified cell culture broth. A comparison between model calculations and experimental data showed a good agreement. The influence of the model parameters is discussed in detail.

  6. Simplified in vitro refolding and purification of recombinant human granulocyte colony stimulating factor using protein folding cation exchange chromatography.

    Science.gov (United States)

    Vemula, Sandeep; Dedaniya, Akshay; Thunuguntla, Rahul; Mallu, Maheswara Reddy; Parupudi, Pavani; Ronda, Srinivasa Reddy

    2015-01-30

    Protein folding-strong cation exchange chromatography (PF-SCX) has been employed for efficient refolding with simultaneous purification of recombinant human granulocyte colony stimulating factor (rhG-CSF). To acquire a soluble form of renatured and purified rhG-CSF, various chromatographic conditions, including the mobile phase composition and pH was evaluated. Additionally, the effects of additives such as urea, amino acids, polyols, sugars, oxidizing agents and their amalgamations were also investigated. Under the optimal conditions, rhG-CSF was efficaciously solubilized, refolded and simultaneously purified by SCX in a single step. The experimental results using ribose (2.0M) and arginine (0.6M) combination were found to be satisfactory with mass yield, purity and specific activity of 71%, ≥99% and 2.6×10(8)IU/mg respectively. Through this investigation, we concluded that the SCX refolding method was more efficient than conventional methods which has immense potential for the large-scale production of purified rhG-CSF.

  7. Role of tentacles and protein loading on pore accessibility and mass transfer in cation exchange materials for proteins.

    Science.gov (United States)

    Thomas, Helen; Coquebert de Neuville, Bertrand; Storti, Giuseppe; Morbidelli, Massimo; Joehnck, Matthias; Schulte, Michael

    2013-04-12

    In protein chromatography, the size of the protein determines which fraction of pores it can access within a resin and at which rate of diffusion. Moreover, in the presence of grafted polymers like in advanced materials, adsorbed proteins and electrolytes complicate the interaction pore-protein. In this study, we evaluated in a comparative way the behavior of Fractogel EMD SO3 (M) and (S), "tentacle"-type, strong cation exchangers, as well as a reference material without tentacles, all of which are commonly used for protein purification. ISEC experiments were carried out with a set of Dextran tracers of largely different molecular size covering the typical range of protein sizes. Experimental values of porosity (internal and external to the particles) as well as of pore diffusion coefficients have been measured at different NaCl concentrations and under protein loading. These results provide useful insights into the complex interplay among mentioned factors: first, the presence of tentacles induces size exclusion selectivity in the materials; second, the salt induces conformational changes of the tentacles, leading to porosities larger than expected in tentacle materials; third, protein adsorption mainly leads to a reduction of porosity due to pore space occupied by the protein and to a decrease of pore diffusion coefficient.

  8. Advanced analytical method of nereistoxin using mixed-mode cationic exchange solid-phase extraction and GC/MS.

    Science.gov (United States)

    Park, Yujin; Choe, Sanggil; Lee, Heesang; Jo, Jiyeong; Park, Yonghoon; Kim, Eunmi; Pyo, Jaesung; Jung, Jee H

    2015-07-01

    Nereistoxin(NTX) was originated from a marine annelid worm Lumbriconereis heteropoda and its analogue pesticides including cartap, bensultap, thiocyclam and thiobensultap have been commonly used in agriculture, because of their low toxicity and high insecticidal activity. However, NTX has been reported about its inhibitory neuro toxicity in human and animal body, by blocking nicotinic acetylcholine receptor and it cause significant neuromuscular toxicity, resulting in respiratory failure. We developed a new method to determine NTX in biological fluid. The method involves mixed-mode cationic exchange based solid phase extraction and gas chromatography/mass spectrometry for final identification and quantitative analysis. The limit of detection and recovery were substantially better than those of other methods using liquid-liquid extraction or headspace solid phase microextraction. The good recoveries (97±14%) in blood samples were obtained and calibration curves over the range 0.05-20 mg/L have R2 values greater than 0.99. The developed method was applied to a fatal case of cartap intoxication of 74 years old woman who ingested cartap hydrochloride for suicide. Cartap and NTX were detected from postmortem specimens and the cause of the death was ruled to be nereistoxin intoxication. The concentrations of NTX were 2.58 mg/L, 3.36 mg/L and 1479.7 mg/L in heart, femoral blood and stomach liquid content, respectively. The heart blood/femoral blood ratio of NTX was 0.76.

  9. Profile Distribution of Exchangeable Cations under No-till and Conventional Tillage in An Aquic Brown Soil%免耕与常规耕作潮棕壤交换性阳离子的剖面分布特征

    Institute of Scientific and Technical Information of China (English)

    孙良杰; 张晓珂; 梁文举

    2009-01-01

    The effects of tillage systems on exchangeable cations of different layers to a 1 m depth in an aquic brown soil were studied in a field experiment. The results showed that no-tillage, compared with conventional tillage, significantly increased soil pH and reduced electronic conductivity (EC) in the 0- 5 cm layer. Soil exchangeable K~+ was improved in no-tillage treatment,while exchangeable Na was declined. However, there was no significant effect of tillage practices on soil exchangeable Ca~(2+) , Mg~(2+) and cation exchange capacity. Correlation analysis showed that no significant correlations were observed between exchangeable K and soil nutrients, whereas exchangeable Na~+ , Ca~(2+) , Mg~(2+) , as well as cation exchange capacity had significant negative correlations with organic matter (OM) and total nitrogen (TN), respectively.%通过田间定位试验.研究了不同耕作方式对潮棕壤0-100 cm深度6个土层土壤交换性阳离子的影响.结果表明,与常规耕作相比,免耕使土壤表层pH显著增,.而电导率下降;同时,免耕增加了表层土壤可交换性K~+含量,降低了可交换性Na~+含量,但对可交换性Ca~(2+),Mg~(2+)和阳离子交换量没有产生显著影响.相关分析结果表明,可交换性K~+与土壤养分含量没有显著相关性,而可交换性Na~+,Ca~(2+),Mg~(2+)和阳离子交换量与有机质和全氮含量均呈负相关关系.

  10. Preliminary Analysis on Heat Removal Capacity of Passive Air-Water Combined Cooling Heat Exchanger Using MARS

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung-Sin; Jeon, Seong-Su; Hong, Soon-Joon [FNC Tech, Yongin (Korea, Republic of); Bae, Sung-Won; Kwon, Tae-Soon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Current design requirement for working time of PAFS heat exchanger is about 8 hours. Thus, it is not satisfied with the required cooling capability for the long term SBO(Station Black-Out) situation that is required to over 72 hours cooling. Therefore PAFS is needed to change of design for 72 hours cooling. In order to acquirement of long terms cooling using PAFS, heat exchanger tube has to be submerged in water tank for long time. However, water in the tank is evaporated by transferred heat from heat exchanger tubes, so water level is gradually lowered as time goes on. The heat removal capacity of air cooling heat exchanger is core parameter that is used for decision of applicability on passive air-water combined cooling system using PAFS in long term cooling. In this study, the development of MARS input model and plant accident analysis are performed for the prediction of the heat removal capacity of air cooling heat exchanger. From analysis result, it is known that inflow air velocity is the decisive factor of the heat removal capacity and predicted air velocity is lower than required air velocity. But present heat transfer model and predicted air velocity have uncertainty. So, if changed design of PAFS that has over 4.6 kW heat removal capacity in each tube, this type heat exchanger can be applied to long term cooling of the nuclear power plant.

  11. {sup 1}H and {sup 23}Na MAS NMR spectroscopy of cationic species in CO{sub 2} selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Arevalo-Hidalgo, Ana G. [Department of Chemical Engineering, University of Puerto Rico-Mayagueez Campus, Mayagueez, PR 00681-9000 (Puerto Rico); Dugar, Sneha; Fu, Riqiang [National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States); Hernandez-Maldonado, Arturo J., E-mail: arturoj.hernandez@upr.edu [Department of Chemical Engineering, University of Puerto Rico-Mayagueez Campus, Mayagueez, PR 00681-9000 (Puerto Rico)

    2012-07-15

    The location of extraframework cations in Sr{sup 2+} and Ba{sup 2+} ion-exchanged SAPO-34 was estimated by means of {sup 1}H and {sup 23}Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO{sub 2} adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium. - Graphical abstract: MAS NMR was used to elucidate the position the cationic species in alkaline earth metal exchanged silicoaluminophosphates. These species played a significant role during the ion exchange process and, therefore, the materials ultimate CO{sub 2} adsorption performance. Highlights: Black-Right-Pointing-Pointer Location of extraframework Sr{sup 2+} or Ba{sup 2+} cations was estimated by means of {sup 1}H and {sup 23}Na MAS NMR. Black-Right-Pointing-Pointer Level of Sr{sup 2+} or Ba{sup 2+} ion exchange was limited by the presence of protons and sodium cations. Black-Right-Pointing-Pointer Presence of ammonium cations in the supercages facilitated the exchange. Black-Right-Pointing-Pointer Sr{sup 2+} and Ba{sup 2+} ion exchanged SAPOs are outstanding CO{sub 2} adsorbents.

  12. The partitioning of sulfur and chlorine between andesite melts and magmatic volatiles and the exchange coefficients of major cations

    Science.gov (United States)

    Zajacz, Zoltán; Candela, Philip A.; Piccoli, Philip M.; Sanchez-Valle, Carmen

    2012-07-01

    Andesite melts were equilibrated with an H-O-S-bearing volatile phase to determine the partition coefficients for S and Cl as a function of melt composition and oxygen fugacity. The experiments were conducted in rapid-quench MHC vessel assemblies at 200 MPa and 1000 °C, and over a range of imposed fO2 between NNO-1.2 and NNO+1.8. High fluid/melt mass ratios (∼15) were employed, allowing precise and accurate partition coefficients to be obtained by mass balance calculations. Chlorine exhibits Henrian behavior at ClO-0.5 activities typical for arc magmas, with D Cl volatile/melt = 1.36 ± 0.06 (1σ) below 0.2 wt.% Cl in the melt; at higher ClO-0.5 activities, D Cl volatile/melt increases linearly to 2.11 ± 0.02 at 1 wt.% Cl in the melt. In the volatile phase: FeCl2 ∼ NaCl > KCl ∼ HCl. The determination of cation exchange coefficients for major cations yielded: K K,Na volatile/melt = 1.23 ± 0.10 (1σ) and ∗K Fe,Na volatile/melt = D Fe volatile/melt / D Na volatile/melt = 1.08 ± 0.16 (1σ). Under these conditions, the concentration of HCl in the vapor is negatively correlated with the (Na + K)/(Al + Fe3+) ratio in the melt. Reduced sulfur (S2-) appears to obey Henry's law in andesite melt-volatile system at fH2S below pyrrhotite saturation. The partition coefficient for S at fO2 = NNO-0.5 correlates negatively with the FeO concentration in the melt, changing from 254 ± 25 at 4.0 wt.% FeO to 88 ± 6 at 7.5 wt.% FeO. Pyrrhotite saturation is reached when approximately 3.2 mol% S is present in the volatile phase at fO2 = NNO-0.5. At the sulfide/sulfate transition, the partition coefficient of S drops from 171 ± 23 to 21 ± 1 at a constant FeO content of ∼6 wt.% in the melt. At fO2 = NNO+1.8, anhydrite saturation is reached at ∼3.3 mol% S present in the volatile phase. Aqueous volatiles exsolving from intermediate to mafic magmas can efficiently extract S, and effect its transfer to sites of magmatic-hydrothermal ore deposit formation.

  13. High-purity isolation of anthocyanins mixtures from fruits and vegetables--a novel solid-phase extraction method using mixed mode cation-exchange chromatography.

    Science.gov (United States)

    He, Jian; Giusti, M Monica

    2011-11-04

    Research on biological activity of anthocyanins requires the availability of high purity materials. However, current methods to isolate anthocyanins or anthocyanin mixtures are tedious and expensive or insufficient for complete isolation. We applied a novel cation-exchange/reversed-phase combination solid-phase extraction (SPE) technique, and optimized the use of water/organic buffer mobile phases to selectively separate anthocyanins. Crude extracts of various representative anthocyanin sources were purified with this technique and compared to 3 commonly used SPE techniques: C(18), HLB, and LH-20. Purified anthocyanin fractions were analyzed with high performance liquid chromatography (HPLC) coupled to photodiode array (PDA) and mass spectrometry (MS) detectors and by Fourier transform infrared (FT-IR) spectroscopy. The UV-visible chromatograms quantitatively demonstrated that our novel technique achieved significantly higher (Panthocyanin purity than the C(18) cartridge, the next best method, for 11 of the 12 anthocyanin sources tested. Among them, eight were purified to greater than 99% purity (based on UV-visible chromatograms). The new method efficiently removed non-anthocyanin phenolics. MS and FT-IR results semi-quantitatively confirmed extensive reduction of impurities. Due to strong ionic interaction, our sorbent capacity was superior to others, resulting in the highest throughput and least use of organic solvents. This new methodology for isolation of anthocyanin mixtures drastically increased purity and efficiency while maintaining excellent recovery rate and low cost. The availability of high purity anthocyanin mixtures will facilitate anthocyanin studies and promote the application of anthocyanins in the food and nutraceutical industries.

  14. Dynamics of the separation of amino acid and mineral salt in the stationary dialysis of solutions with an MK-40 profiled sulfo group cation exchange membrane

    Science.gov (United States)

    Vasil'eva, V. I.; Vorob'eva, E. A.

    2012-11-01

    The conjugated diffusion transport of amino acid and mineral salt through a profiled sulfo group cation exchange membrane that simulates the extraction of amino acid from wash waters of microbiological production containing mineral components not used in synthesis is studied. The competitive nature of the conjugation of flows resulting in a decrease in the rate of the mass transfer of components and their separation factor is established from a comparative analysis of experimental data on the diffusion transfer of phenylalanine and sodium chloride in the form of hydrogen from individual and mixed solutions through a profiled sulfo group cation exchange membrane. The range of concentrations and the ratio of components in solution corresponding to the effective separation of phenylalanine and sodium chloride are determined.

  15. Characteristics of Lipoprotein Peak x Eluted from a Column with the Eluent of High-magnesium Ion Concentration in Lipoprotein Analysis Using the Cation-exchange Chromatography

    OpenAIRE

    Yuji Hirowatari; Hiroshi Yoshida; Yutaka Ogura; Hidekastu Yanai; Hideo Kurosawa; Norio Tada

    2005-01-01

    The new lipoprotein analysis method using a cation-exchange chromatography, which contains a sulfopropyl-ligand column and two magnesium ion-containing eluents was previously reported. This method can separate serum lipoproteins on the column gel with a magnesium ion concentration gradient and high-density lipoprotein (HDL), low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL) and an unspecified lipoprotein peak are eluted in order from the column. We have now characterize...

  16. High pH reversed-phase chromatography with fraction concatenation as an alternative to strong-cation exchange chromatography for two-dimensional proteomic analysis

    OpenAIRE

    Yang, Feng; Shen, Yufeng; Camp, David G.; Smith, Richard D.

    2012-01-01

    Orthogonal high-resolution separations are critical for attaining improved analytical dynamic range and protein coverage in proteomic measurements. High pH reversed-phase liquid chromatography (RPLC) followed by fraction concatenation affords better peptide analysis than conventional strong-cation exchange (SCX) chromatography applied for the two-dimensional proteomic analysis. For example, concatenated high pH reversed-phase liquid chromatography increased identification for peptides (1.8-fo...

  17. Controllable conversion of plasmonic Cu2-xS nanoparticles to Au2S by cation exchange and electron beam induced transformation of Cu2-xS-Au2S core/shell nanostructures.

    Science.gov (United States)

    Wang, Xianliang; Liu, Xin; Zhu, Dewei; Swihart, Mark T

    2014-08-01

    Self-doped Cu2-xS nanocrystals (NCs) were converted into monodisperse Cu2-xS-Au2S NCs of tunable composition, including pure Au2S, by cation exchange. The near-infrared (NIR) localized surface plasmon resonance (LSPR) was dampened and red-shifted with increasing Au content. Cation exchange was accompanied by elimination of cation vacancies and a change in crystal structure. Partially exchanged Cu2-xS-Au2S core/shell structures evolved to dumbbell-like structures under electron irradiation in the transmission electron microscope (TEM).

  18. Influence of lime, peat and cation exchanger on the heavy-metal-uptake of vine (Vitis vinifera L. ) from contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Mohr, H.D.

    1980-10-01

    In pot experiments with heavy-metal-contaminated soils, the influence of different soil admixtures on growth and heavy-metal-uptake of vine cuttings was investigated. The following results were obtained: 1. The heavy metal uptake of vines from mixtures of soil and garbage-sewage-compost was strongly reduced by a cation exchanger. The heavy metal content of the roots decreased as follows: Cu68-77%; Zn36-74%; Cd29-81%; Mn20-45%; Pb13-52%; Cr7-58%. The Mn-, Zn- and Cu-content of wood, tendrils and leaves also decreased considerably. 2. Vine cuttings, which were cultivated on an acid, artificially Cd-contaminated soil, showed heavy damages and high Cd-contents. Admixtures of lime, cation exchanger or garbage-sewage-sludge-compost strongly reduced the injury of vines and their Cd-content. A combined addition of lime and cation exchanger was most effectful. On the contrary, the toxic effect of Cd was intensified by the acid reaction of peat.

  19. Effect of the intercalated cation-exchanged on the properties of nanocomposites prepared by 2-aminobenzene sulfonic acid with aniline and montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Toumi, I. [Laboratoire de Chimie Organique, Macromoleculaire et des Materiaux, Universite de Mascara, Bp 763 Mascara 29000 (Algeria); Benyoucef, A., E-mail: ghani29000@yahoo.fr [Laboratoire de Chimie Organique, Macromoleculaire et des Materiaux, Universite de Mascara, Bp 763 Mascara 29000 (Algeria); Yahiaoui, A. [Laboratoire de Chimie Organique, Macromoleculaire et des Materiaux, Universite de Mascara, Bp 763 Mascara 29000 (Algeria); Quijada, C. [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, Pza Ferrandiz i Carbonel, E-03801 Alcoy, Alicante (Spain); Morallon, E. [Departamento de Quimica Fisica e Instituto Universitario de Materiales, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)

    2013-02-25

    Polymer/montmorillonite nanocomposites were prepared. Intercalation of 2-aminobenzene sulfonic acid with aniline monomers into montmorillonite modified by cation was followed by subsequent oxidative polymerization of monomers in the interlayer spacing. The clay was prepared by cation exchange process between sodium cation in (M-Na) and copper cation (M-Cu). XRD analyses show the manifestation of a basal spacing (d-spacing) for M-Cu changes depending on the inorganic cation and the polymer intercalated in the M-Cu structure. TGA analyses reveal that polymer/M-Cu composites is less stable than M-Cu. The conductivity of the composites is found to be 10{sup 3} times higher than that for M-Cu. The microscopic examinations including TEM picture of the nanocomposite demonstrated an entirely different and more compatible morphology. Remarkable differences in the properties of the polymers have also been observed by UV-Vis and FTIR, suggesting that the polymer produced with presence of aniline has a higher degree of branching. The electrochemical behavior of the polymers extracted from the nanocomposites has been studied by cyclic voltammetry which indicates the electroactive effect of nanocomposite gradually increased with aniline in the polymer chain.

  20. Unfolding and aggregation of monoclonal antibodies on cation exchange columns: effects of resin type, load buffer, and protein stability.

    Science.gov (United States)

    Guo, Jing; Carta, Giorgio

    2015-04-03

    The chromatographic behavior of a monoclonal antibody (mAb) that exhibits a pronounced two-peak elution behavior is studied for a range of strong cation exchange resins and with varying load buffer pH and composition. Six stationary phases are considered, including two tentacle-type resins (Fractogel EMD SO3-(M) and Eshmuno S), a resin with grafted polymeric surface extenders (Nuvia S), a resin with a bimodal pore size distribution (POROS HS 50), and two macroporous resins without polymer grafts (Source 30S and UNOsphere Rapid S). The two-peak elution behavior is very pronounced for the tentacle and polymer-grafted resins and for POROS HS 50, but is essentially absent for the two macroporous resins. The extent of this behavior decreases as the buffer pH and concentration increase and, consequently, mAb binding becomes weaker. Replacing sodium with arginine as the buffer counterion, which is expected to decrease the mAb binding strength, nearly completely eliminates the two-peak behavior, while replacing sodium with tetra-n-butylammonium hydroxide, which is expected to increase the mAb binding strength, dramatically exacerbate the effect. As shown by hydrogen-deuterium exchange mass spectrometry (HX-MS), the two-peak elution behavior is related to conformational changes that occur when the mAb binds. These changes result in increased solvent exposure of specific peptides in the Fc-region for either the Fractogel or the Nuvia resin. No significant conformational changes were seen by HX-MS when the mAb was bound to the UNOsphere resin or on the Fractogel resin when arginine was used in lieu of sodium as the load buffer counterion. Experiments with two additional mAbs on the Fractogel resin show that the two-peak elution behavior is dependent on the particular antibody. Circular dichroism suggests that the propensity of different mAbs to either precipitate directly or to form stabilizing intermolecular structures upon exposure to thermal stress can be related to their

  1. Tuning Equilibrium Compositions in Colloidal Cd1-xMnxSe Nanocrystals Using Diffusion Doping and Cation Exchange.

    Science.gov (United States)

    Barrows, Charles J; Chakraborty, Pradip; Kornowske, Lindsey M; Gamelin, Daniel R

    2016-01-26

    The physical properties of semiconductor nanocrystals can be tuned dramatically via composition control. Here, we report a detailed investigation of the synthesis of high-quality colloidal Cd1-xMnxSe nanocrystals by diffusion doping of preformed CdSe nanocrystals. Until recently, Cd1-xMnxSe nanocrystals proved elusive because of kinetic incompatibilities between Mn(2+) and Cd(2+) chemistries. Diffusion doping allows Cd1-xMnxSe nanocrystals to be prepared under thermodynamic rather than kinetic control, allowing access to broader composition ranges. We now investigate this chemistry as a model system for understanding the characteristics of nanocrystal diffusion doping more deeply. From the present work, a Se(2-)-limited reaction regime is identified, in which Mn(2+) diffusion into CdSe nanocrystals is gated by added Se(2-), and equilibrium compositions are proportional to the amount of added Se(2-). At large added Se(2-) concentrations, a solubility-limited regime is also identified, in which x = xmax = ∼0.31, independent of the amount of added Se(2-). We further demonstrate that Mn(2+) in-diffusion can be reversed by cation exchange with Cd(2+) under exactly the same reaction conditions, purifying Cd1-xMnxSe nanocrystals back to CdSe nanocrystals with fine tunability. These chemistries offer exceptional composition control in Cd1-xMnxSe NCs, providing opportunities for fundamental studies of impurity diffusion in nanocrystals and for development of compositionally tuned nanocrystals with diverse applications ranging from solar energy conversion to spin-based photonics.

  2. Cation exchange synthesis of uniform PbSe/PbS core/shell tetra-pods and their use as near-infrared photodetectors

    Science.gov (United States)

    Mishra, N.; Mukherjee, B.; Xing, G.; Chakrabortty, S.; Guchhait, A.; Lim, J. Y.

    2016-07-01

    In this work we explore the preparation of complex-shaped semiconductor nanostructures composed of different materials via a cationic exchange process in which the cations of the original semiconductor nanostructure are replaced by cations of different metals with preservation of the shape and the anionic framework of the nanocrystals. Utilizing this cation exchange method, we synthesized two new tetrapods for the first time: Cu2-xSe/Cu2-xS and PbSe/PbS, both prepared from CdSe/CdS tetrapods as `templates'. We also fabricated near-infrared (NIR) photodetectors with a very simple architecture comprising a PbSe/PbS tetrapod layer between two Au electrodes on a glass substrate. When illuminated by a NIR laser, these devices are capable of achieving a responsivity of 11.9 A W-1 without the use of ligand-exchange processes, thermal annealing or hybrid device architecture. Transient absorption spectroscopy was carried out on these PbSe/PbS tetrapods, the results of which suggest that the branched morphology contributes in part to device performance. Investigation of the charge dynamics of the PbSe/PbS tetrapods revealed an extremely long-lived exciton recombination lifetime of ~17 ms, which can result in enhanced photoconductive gain. Overall, these heterostructured tetrapods showcase simultaneously the importance of nanoparticle shape, band structure, and surface chemistry in the attainment of NIR photodetection.In this work we explore the preparation of complex-shaped semiconductor nanostructures composed of different materials via a cationic exchange process in which the cations of the original semiconductor nanostructure are replaced by cations of different metals with preservation of the shape and the anionic framework of the nanocrystals. Utilizing this cation exchange method, we synthesized two new tetrapods for the first time: Cu2-xSe/Cu2-xS and PbSe/PbS, both prepared from CdSe/CdS tetrapods as `templates'. We also fabricated near-infrared (NIR) photodetectors

  3. Insights in understanding aggregate formation and dissociation in cation exchange chromatography for a structurally unstable Fc-fusion protein.

    Science.gov (United States)

    Chen, Zhiqiang; Huang, Chao; Chennamsetty, Naresh; Xu, Xuankuo; Li, Zheng Jian

    2016-08-19

    Cation-exchange chromatography (CEX) of a structurally unstable Fc-fusion protein exhibited multi-peak elution profile upon a salt-step elution due to protein aggregation during intra-column buffer transition where low pH and high salt coexisted. The protein exhibited a single-peak elution behavior during a pH-step elution; nevertheless, the levels of soluble aggregates (i.e. high molecular weight species, HMW) in the CEX eluate were still found up to 12-fold higher than that for the load material. The amount of the aggregates formed upon the pH-step elution was dependent on column loading with maximum HMW achieved at intermediate loading levels, supporting the hypothesis that the aggregation was the result of both the conformational changes of the bound protein and the solution concentration of the aggregation-susceptible proteins during elution. Factors such as high load pH, short protein/resin contact time, hydrophilic resin surface, and weak ionizable ligand were effective, to some extent, to reduce aggregate formation by improving the structural integrity of the bound protein. An orthogonal technique, differential scanning fluorimetry (DSF) using Sypro Orange dye confirmed that the bound protein exposed more hydrophobic area than the native molecule in free solution, especially in the pH 4-5 range. The Sypro Orange dye study of resin surface property also demonstrated that the poly[styrene-divinylbenzene]-based Poros XS with polyhydroxyl surface coating is more hydrophobic compared to the agarose-based CM Sepharose FF and SP Sepharose FF. The hydrophobic property of Poros XS contributed to stronger interactions with the partially unfolded bound protein and consequently to the higher aggregate levels seen in Poros XS eluate. This work also investigates the aggregation reversibility in CEX eluate where up to 66% of the aggregates were observed to dissociate into native monomers over a period of 120h, and links the aggregate stability to such conditions as resin

  4. Alveolar gas exchange and tissue oxygenation during incremental treadmill exercise, and their associations with blood O(2) carrying capacity.

    Science.gov (United States)

    Rissanen, Antti-Pekka E; Tikkanen, Heikki O; Koponen, Anne S; Aho, Jyrki M; Hägglund, Harriet; Lindholm, Harri; Peltonen, Juha E

    2012-01-01

    The magnitude and timing of oxygenation responses in highly active leg muscle, less active arm muscle, and cerebral tissue, have not been studied with simultaneous alveolar gas exchange measurement during incremental treadmill exercise. Nor is it known, if blood O(2) carrying capacity affects the tissue-specific oxygenation responses. Thus, we investigated alveolar gas exchange and tissue (m. vastus lateralis, m. biceps brachii, cerebral cortex) oxygenation during incremental treadmill exercise until volitional fatigue, and their associations with blood O(2) carrying capacity in 22 healthy men. Alveolar gas exchange was measured, and near-infrared spectroscopy (NIRS) was used to monitor relative concentration changes in oxy- (Δ[O(2)Hb]), deoxy- (Δ[HHb]) and total hemoglobin (Δ[tHb]), and tissue saturation index (TSI). NIRS inflection points (NIP), reflecting changes in tissue-specific oxygenation, were determined and their coincidence with ventilatory thresholds [anaerobic threshold (AT), respiratory compensation point (RC); V-slope method] was examined. Blood O(2) carrying capacity [total hemoglobin mass (tHb-mass)] was determined with the CO-rebreathing method. In all tissues, NIPs coincided with AT, whereas RC was followed by NIPs. High tHb-mass associated with leg muscle deoxygenation at peak exercise (e.g., Δ[HHb] from baseline walking to peak exercise vs. tHb-mass: r = 0.64, p capacity for blood O(2) carrying was associated with a high level of m. vastus lateralis deoxygenation at peak exercise.

  5. Rapid Preparation of Biosorbents with High Ion Exchange Capacity from Rice Straw and Bagasse for Removal of Heavy Metals

    Directory of Open Access Journals (Sweden)

    Supitcha Rungrodnimitchai

    2014-01-01

    Full Text Available This work describes the preparation of the cellulose phosphate with high ion exchange capacity from rice straw and bagasse for removal of heavy metals. In this study, rice straw and bagasse were modified by the reaction with phosphoric acid in the presence of urea. The introduced phosphoric group is an ion exchangeable site for heavy metal ions. The reaction by microwave heating yielded modified rice straw and modified bagasse with greater ion exchange capacities (∼3.62 meq/g and shorter reaction time (1.5–5.0 min than the phosphorylation by oil bath heating. Adsorption experiments towards Pb2+, Cd2+, and Cr3+ ions of the modified rice straw and the modified bagasse were performed at room temperature (heavy metal concentration 40 ppm, adsorbent 2.0 g/L. The kinetics of adsorption agreed with the pseudo-second-order model. It was shown that the modified rice straw and the modified bagasse could adsorb heavy metal ions faster than the commercial ion exchange resin (Dowax. As a result of Pb2+ sorption test, the modified rice straw (RH-NaOH 450W removed Pb2+ much faster in the initial step and reached 92% removal after 20 min, while Dowax (commercial ion exchange resin took 90 min for the same removal efficiency.

  6. Separation of aliphatic carboxylic acids and benzenecarboxylic acids by ion-exclusion chromatography with various cation-exchange resin columns and sulfuric acid as eluent.

    Science.gov (United States)

    Ohta, Kazutoku; Ohashi, Masayoshi; Jin, Ji-Ye; Takeuchi, Toyohide; Fujimoto, Chuzo; Choi, Seong-Ho; Ryoo, Jae-Jeong; Lee, Kwang-Pill

    2003-05-16

    The application of various hydrophilic cation-exchange resins for high-performance liquid chromatography (sulfonated silica gel: TSKgel SP-2SW, carboxylated silica gel: TSKgel CM-2SW, sulfonated polymethacrylate resin: TSKgel SP-5PW, carboxylated polymethacrylate resins: TSKgel CM-5PW and TSKgel OA-Pak A) as stationary phases in ion-exclusion chromatography for C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, butyric, isovaleric, valeric, isocaproic, caproic, 2-methylhexanoic and heptanoic acids) and benzenecarboxylic acids (pyromellitic, trimellitic, hemimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic, salicylic acids and phenol) was carried out using diluted sulfuric acid as the eluent. Silica-based cation-exchange resins (TSKgel SP-2SW and TSKgel CM-2SW) were very suitable for the ion-exclusion chromatographic separation of these benzenecarboxylic acids. Excellent simultaneous separation of these benzenecarboxylic acids was achieved on a TSKgel SP-2SW column (150 x 6 mm I.D.) in 17 min using a 2.5 mM sulfuric acid at pH 2.4 as the eluent. Polymethacrylate-based cation-exchange resins (TSKgel SP-5PW, TSKgel CM-5PW and TSKgel OA-Pak A) acted as advanced stationary phases for the ion-exclusion chromatographic separation of these C1-C7 aliphatic carboxylic acids. Excellent simultaneous separation of these C1-C7 acids was achieved on a TSKgel CM-5PW column (150 x 6 mm I.D.) in 32 min using a 0.05 mM sulfuric acid at pH 4.0 as the eluent.

  7. Hybrid organic-inorganic silica monolith with hydrophobic/strong cation-exchange functional groups as a sorbent for micro-solid phase extraction.

    Science.gov (United States)

    Zheng, Ming-Ming; Ruan, Ge-Deng; Feng, Yu-Qi

    2009-11-06

    A hybrid organic-inorganic silica monolith with hydrophobic and strong cation-exchange functional groups was prepared and used as a sorbent for micro-solid phase extraction (micro-SPE). The hybrid silica monolith functionalized with octyl and thiol groups was conveniently synthesized by hydrolysis and polycondensation of a mixture of tetraethoxysilane (TEOS), n-octyltriethoxysilane (C8-TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) via a two-step catalytic sol-gel process. Due to the favorable chemical reactivity of mercapto pendant moieties, the obtained hybrid monolith was oxidized using hydrogen peroxide (30%, w/w) to yield sulfonic acid groups, which provided strong cation-exchange sites. The obtained hybrid monolith was characterized by diffused infrared spectroscopy, elemental analysis, scanning electron microscopy and mercury intrusion porosimetry. The results show that the resulting monolith contains much higher carbon (31.6%) and sulfur (4.8%) contents than traditionally bonded silica materials. The extraction performance of the hybrid monolith was evaluated using sulfonamides as testing analytes by micro-SPE on-line coupled to HPLC. The results show that the hybrid monolith with hydrophobic and strong cation-exchange functional groups exhibits high extraction efficiency towards the testing analytes. The column-to-column RSD values were 1.3-9.8% for the extraction of SAs investigated. The extraction performance of the hybrid silica monolith remained practically unchanged after treated with acid (pH 1.0) and basic solutions (pH 10.5). Finally, the application of the hybrid monolith was demonstrated by micro-SPE of sulfonamide residues from milk followed by HPLC-UV analysis. The limits of detection (S/N=3) for eight SAs were found to be 1.0-3.0ng/mL in milk. The recoveries of eight SAs spiked in milk sample ranged from 80.2% to 115.6%, with relative standard deviations less than 11.8%.

  8. Near-Infrared Emitting CuInSe2/CuInS2 Dot Core/Rod Shell Heteronanorods by Sequential Cation Exchange

    OpenAIRE

    2015-01-01

    The direct synthesis of heteronanocrystals (HNCs) combining different ternary semiconductors is challenging and has not yet been successful. Here, we report a sequential topotactic cation exchange (CE) pathway that yields CuInSe2/CuInS2 dot core/rod shell nanorods with near-infrared luminescence. In our approach, the Cu+ extraction rate is coupled to the In3+ incorporation rate by the use of a stoichiometric trioctylphosphine-InCl3 complex, which fulfills the roles of both In-source and Cu-ex...

  9. Near-infrared emitting CuInSe_{2}/CuInS_{2} dot core/rod shell heteronanorods by sequential cation exchange

    OpenAIRE

    2015-01-01

    Abstract: The direct synthesis of heteronanocrystals (HNCs) combining different ternary semiconductors is challenging and has not yet been successful. Here, we report a sequential topotactic cation exchange (CE) pathway that yields CuInSe2/CuInS2 dot core/rod shell nanorods with near-infrared luminescence. In our approach, the Cu+ extraction rate is coupled to the In3+ incorporation rate by the use of a stoichiometric trioctylphosphine-InCl3 complex, which fulfills the roles of both In-source...

  10. Synthesis of Flexible Heat Exchanger Networks with Stream Splits Based on Rangers of Stream Supply Temperatures and Heat Capacity Flowrates

    Institute of Scientific and Technical Information of China (English)

    李志红; 罗行; 华贵; W.Roetzel

    2004-01-01

    A new superstructure model of heat exchanger networks (HEN) with stream splits based on rangers of streams supply temperatures and heat capacity flow rates is presented. The simultaneous optimal mathematical model of flexible HEN synthesis is established too. Firstly, the streams with rangers of supply temperatures and/or the streams with the rangers of heat capacity flow rates are pretreated; Secondly, several rules are proposed to establish the superstructure model of HEN with splits and the simultaneous optimal mathematical model of flexible HEN; Thirdly, the improving genetic algorithm is applied to solve the mathematical model established at the second step effectively, and the original optimal structure of HEN based on the maximum operation limiting condition can be obtained easily; Finally, the rules of heat exchange unit merged and the heat load of heat exchanger relaxed are presented, the flexible configuration of HEN satisfied the operation condition between the upper and down bounds of supply temperature and heat capacity flow rates can be obtained based on the original optimal structure of HEN by means of these rules. A case study demonstrates the method presented in this paper is effective

  11. Cationic reverse micelles create water with super hydrogen-bond-donor capacity for enzymatic catalysis: hydrolysis of 2-naphthyl acetate by alpha-chymotrypsin.

    Science.gov (United States)

    Moyano, Fernando; Falcone, R Dario; Mejuto, J C; Silber, Juana J; Correa, N Mariano

    2010-08-02

    Reverse micelles (RMs) are very good nanoreactors because they can create a unique microenvironment for carrying out a variety of chemical and biochemical reactions. The aim of the present work is to determine the influence of different RM interfaces on the hydrolysis of 2-naphthyl acetate (2-NA) by alpha-chymotrypsin (alpha-CT). The reaction was studied in water/benzyl-n-hexadecyldimethylammonium chloride (BHDC)/benzene RMs and, its efficiency compared with that observed in pure water and in sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) RMs. Thus, the hydrolysis rates of 2-NA catalyzed by alpha-CT were determined by spectroscopic measurements. In addition, the method used allows the joint evaluation of the substrate partition constant K(p) between the organic and the micellar pseudophase and the kinetic parameters: catalytic rate constant k(cat), and the Michaelis constant K(M) of the enzymatic reaction. The effect of the surfactant concentration on the kinetics parameters was determined at constant W(0)=[H(2)O]/[surfactant], and the variation of W(0) with surfactant constant concentration was investigated. The results show that the classical Michaelis-Menten mechanism is valid for alpha-CT in all of the RMs systems studied and that the reaction takes place at both RM interfaces. Moreover, the catalytic efficiency values k(cat)/K(M) obtained in the RMs systems are higher than that reported in water. Furthermore, there is a remarkable increase in alpha-CT efficiency in the cationic RMs in comparison with the anionic system, presumably due to the unique water properties found in these confined media. The results show that in cationic RMs the hydrogen-bond donor capacity of water is enhanced due to its interaction with the cationic interface. Hence, entrapped water can be converted into "super-water" for the enzymatic reaction studied in this work.

  12. Effect of Zeolite Modification via Cationic Exchange Method on Mechanical, Thermal, and Morphological Properties of Ethylene Vinyl Acetate/Zeolite Composites

    Directory of Open Access Journals (Sweden)

    N. D. Zaharri

    2013-01-01

    Full Text Available In this research, organozeolite filled ethylene vinyl acetate (EVA composites were prepared in a melt-mixing process and followed by compression molding using hot press machine according to standard test specimen. Prior to mixing process, zeolite was modified via cationic exchange of alkylammonium ions. The effect of zeolite or organozeolite loading from 5 up to 25 volume percentages on the properties of EVA/zeolite composites was evaluated. A combination of Fourier Transform Infrared Radiation (FTIR and scanning electron microscopy (SEM coupled with energy dispersive X-ray (EDX analysis were done to characterize the resultant organoclay. Tensile test was performed in order to study the mechanical properties of the composites. EVA filled with organozeolite showed better tensile properties compared to EVA filled with unmodified zeolite, which might be an indication of enhanced dispersion of organophilic clay in the composites. Meanwhile, morphological study using SEM revealed the fibrillation effect of organozeolite. Besides, thermal properties of the composites were also characterized by using thermogravimetric analysis (TGA and differential scanning calorimetry (DSC. The results showed that the application of the cation exchange treatment increases both decomposition and melting temperature of EVA/zeolite composites.

  13. COMPOSITE OF CHITOSAN VANILIN / SULFONATED POLYSTYRENE AS POLYMER ELECTROLYTE MEMBRANES : CATIONIC EXCHANGE CAPACITY, SWELLING DEGREE AND THERMAL PROPERTIES

    OpenAIRE

    Edi Pramono; Candra Purnawan; Yuniawan Hidayat; Jati Wulansari; Sayekti Wahyuningsih

    2016-01-01

    Research on the preparation and characterization of sulfonated polystyrene (PST) /chitosan vanillin (KV) composite as electrolyte membranes has been conducted in order to investigate the effect of PST and KV composition to its chemical and physical properties. Polystyrene was modified by sulfonation reaction to produces PST, meanwhile chitosan was modified by schift base reaction to produces KV. The composite membranes were prepared by casting method and were characterized in order to identi...

  14. Phytochemical profile and ABTS cation radical scavenging, cupric reducing antioxidant capacity and anticholinesterase activities of endemic Ballota nigra L. subsp. anatolica P.H. Davis from Turkey

    Institute of Scientific and Technical Information of China (English)

    Abdulselam Erta; Mehmet Boa; Yeter Yeil

    2014-01-01

    Objective: To evaluate the chemical compositions and biological activities of an endemic Ballotanigra Methods: Essential oil and fatty acid composition were determined by GC/MS analysis. ABTS cation radical decolourisation and cupric reducing antioxidant capacity assays were carried out to indicate the antioxidant activity. The anticholinesterase potential of the extracts were determined by Ellman method. L. subsp. anatolica P.H. Davis. Results: The major compounds in the fatty acid composition of the petroleum ether extract were identified as palmitic (36.0%) and linoleic acids (14.3%). The major components of essential oil were 1-hexacosanol (26.7%), germacrene-D (9.3%) and caryophyllene oxide (9.3%). The water extract indicated higher ABTS cation radical scavenging activity than α-tocopherol and BHT, at 100 µg/mL. The acetone extract showed 71.58 and 44.71% inhibitory activity against butyrylcholinesterase and acetylcholinesterase enzyme at 200 µg/mL, respectively. Conclusions: The water and acetone extracts of Ballota nigra subsp. anatolica can be investigated in terms of both phytochemical and biological aspects to find natural active compounds.

  15. Effect of fouling on the capacity and breakthrough characteristics of a packed bed ion exchange chromatography column.

    Science.gov (United States)

    Siu, Sun Chau; Baldascini, Helen; Hearle, David C; Hoare, Mike; Titchener-Hooker, Nigel J

    2006-05-01

    This study examined the impact of fouling with yeast homogenate on capacity and breakthrough performance of an ion exchange packed bed column. Column performance was assessed by analysis of breakthrough curves obtained with BSA as a test protein. The overall impact of fouling on breakthrough performance depended heavily on the level of clarification of the feed stream. Challenging the column with particulate-free homogenate caused no change in column performance. Loading successive small volumes of poorly clarified homogenate, interspersed with frequent column salt washes, did not alter significantly the column capacity. By contrast, when the column was challenged with an equivalent cumulative volume of poorly clarified homogenate, dynamic binding capacity decreased significantly and changes in breakthrough curves suggested increased intraparticle and external mass transfer limitations. These changes were ascribed to deposition of solid particulates in void spaces in the bed and colloidal contaminants in the bead pores.

  16. [Prone position: effect on gas exchange and functional capacity for exercise in patients with pulmonary hypertension].

    Science.gov (United States)

    Bastidas-L, Andrea Carolina; Colina-Chourio, José A; Guevara, Jesnel M; Nunez, Alexis

    2015-03-01

    The objective of this investigation was to evaluate gas exchange and cardiopulmonary functional behavior in patients with pulmonary hypertension (PH) before, during and after the change to a prone position. Thirty patients with PH and alterations in gas exchange were included in the study. Gas exchange measurements were performed in four stages: at the baseline supine position and after 30, 120 and 240 minutes in prone position. Also, the patients were evaluated by the six minutes walking test (6MWT) after 30 days in prone position during night's sleep. After four hours in prone position, all patients showed an increase of PaO2 and arterial saturation of oxygen (SaO2), with a decrease of intrapulmonary shunts, improving the gas exchange and therefore the physiological demand imposed by exercise in patients with PH.

  17. Esterification of Waste Frying Oil Using Styrene Type Cation Exchange Resin Catalyst%苯乙烯型阳离子交换树脂催化废煎炸油的酯化反应

    Institute of Scientific and Technical Information of China (English)

    吕鹏梅; 刘莉梅; 杨玲梅; 袁振宏; 陈子博

    2014-01-01

    Porous polystyrene-divinylbenzene was prepared by suspension polymerization,and then sulfonie acid ion exchange resin was obtained by sulfonated porous polystyrene-divinylbenzene.The resin' s morphology and degree of sulfonation were characterized with SEM/EDS,BET,IR respectively.Esterification of waste frying oils with acid value of 63.0 mg/g was studied using cation exchange resin as catalyst to investigate its catalytic activity.40.0% dosage of porogen was preferred when the polymerization conditions were 360 r/min,1.0% dispersant,1.0% initiator,75℃ for 4 h and the heat to 85 ℃ for 6 h,while the sulfonation conditions were 1.0 mL/g dichloroethane,5.0 mL/g sulfuric acid,70℃ sulfonated for 1 h and the heat to 80 ~ 85℃ for 3 h,the optimum swelling time was 1 h,and the concentration of sulfuric acid was 98%.The maximum exchange capacity of the cation exchange resin W2 was 5.2 mmol/g in that condition.When the esterification was performed in the condition of 40.0% methanol,10.0% W2,70℃ stirring.for 1.5 h,the crushing rate of W2 was only 10.0% and the conversion rate of FFA reached to 86.8%.W2 is better than commercially available cation exchange resin PC101,and could be reused for 5 times.%以液体石蜡、邻苯二甲酸二丁酯为混合致孔剂,采用悬浮聚合法制备多孔聚苯乙烯-二乙烯苯,磺化后得到磺酸型阳离子交换树脂.利用SEM/EDS、BET、IR等手段对其形貌、磺化程度进行表征,并通过酸值为63.0 mg/g(以KOH计)煎炸油的酯化反应考察催化剂的活性.结果表明:磺酸根基团成功接到PS分子链上;在聚合条件为360 r/min、1.0%分散剂、1.0%引发剂、75℃保温4h、升温至85℃保温6h时,混合致孔剂的最佳添加量为40.0%液体石蜡、50.0%邻苯二甲酸二丁酯;在磺化条件为二氯乙烷1.0 mL/g、硫酸5.0 mL/g、70℃磺化1h后升温至80~85℃磺化3h时的最佳溶胀时间为1h、硫酸体积分数98%,

  18. Investigation of the swelling behavior of cationic exchange resins saturated with Na{sup +} ions in a C{sub 3}S paste

    Energy Technology Data Exchange (ETDEWEB)

    Lafond, E. [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Cau Dit Coumes, C., E-mail: celine.cau-dit-coumes@cea.fr [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Gauffinet, S. [UMR5209 Institut Carnot de Bourgogne, Université de Bourgogne Dijon, Faculté des Sciences Mirande, 9 Avenue Alain Savary, BP 47870, 21078 Dijon cedex (France); Chartier, D. [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Le Bescop, P. [CEA, DEN, DPC, SECR, F-91192 Gif-sur-Yvette (France); Stefan, L. [AREVA, Back End Business Group, Dismantling & Services, 1 place Jean Millier, 92084 Paris La Défense (France); Nonat, A. [UMR5209 Institut Carnot de Bourgogne, Université de Bourgogne Dijon, Faculté des Sciences Mirande, 9 Avenue Alain Savary, BP 47870, 21078 Dijon cedex (France)

    2015-03-15

    Ion exchange resins (IERs) are widely used by the nuclear industry to decontaminate radioactive effluents. Spent products are usually encapsulated in cementitious materials. However, the solidified waste form can exhibit strong expansion, possibly leading to cracking, if the appropriate binder is not used. In this work, the interactions between cationic resins in the Na{sup +} form and tricalcium silicate are investigated during the early stages of hydration in order to gain a better understanding of the expansion process. It is shown that the IERs exhibit a transient swelling of small magnitude due to the decrease in the osmotic pressure of the external solution. This expansion, which occurs just after setting, is sufficient to damage the material which is poorly consolidated for several reasons: low degree of hydration, precipitation of poorly cohesive sodium-bearing C–S–H, and very heterogeneous microstructure with zones of high porosity.

  19. Zwitterionic and cationic bis(phosphine) platinum(II) complexes: structural, electronic, and mechanistic comparisons relevant to ligand exchange and benzene C-H activation processes.

    Science.gov (United States)

    Thomas, J Christopher; Peters, Jonas C

    2003-07-23

    Structurally similar but charge-differentiated platinum complexes have been prepared using the bidentate phosphine ligands [Ph(2)B(CH(2)PPh(2))(2)], ([Ph(2)BP(2)], [1]), Ph(2)Si(CH(2)PPh(2))(2), (Ph(2)SiP(2), 2), and H(2)C(CH(2)PPh(2))(2), (dppp, 3). The relative electronic impact of each ligand with respect to a coordinated metal center's electron-richness has been examined using comparative molybdenum and platinum model carbonyl and alkyl complexes. Complexes supported by anionic [1] are shown to be more electron-rich than those supported by 2 and 3. A study of the temperature and THF dependence of the rate of THF self-exchange between neutral, formally zwitterionic [Ph(2)BP(2)]Pt(Me)(THF) (13) and its cationic relative [(Ph(2)SiP(2))Pt(Me)(THF)][B(C(6)F(5))(4)] (14) demonstrates that different exchange mechanisms are operative for the two systems. Whereas cationic 14 displays THF-dependent, associative THF exchange in benzene, the mechanism of THF exchange for neutral 13 appears to be a THF independent, ligand-assisted process involving an anchimeric, eta(3)-binding mode of the [Ph(2)BP(2)] ligand. The methyl solvento species 13, 14, and [(dppp)Pt(Me)(THF)][B(C(6)F(5))(4)] (15), each undergo a C-H bond activation reaction with benzene that generates their corresponding phenyl solvento complexes [Ph(2)BP(2)]Pt(Ph)(THF) (16), [(Ph(2)SiP(2))Pt(Ph)(THF)][B(C(6)F(5))(4)] (17), and [(dppp)Pt(Ph)(THF)][B(C(6)F(5))(4)] (18). Examination of the kinetics of each C-H bond activation process shows that neutral 13 reacts faster than both of the cations 14 and 15. The magnitude of the primary kinetic isotope effect measured for the neutral versus the cationic systems also differs markedly (k(C(6)H(6))/k(C(6)D(6)): 13 = 1.26; 14 = 6.52; 15 approximately 6). THF inhibits the rate of the thermolysis reaction in all three cases. Extended thermolysis of 17 and 18 results in an aryl coupling process that produces the dicationic, biphenyl-bridged platinum dimers [[(Ph(2)SiP(2))Pt](2

  20. Ergot alkaloids in rye flour determined by solid-phase cation-exchange and high-pressure liquid chromatography with fluorescence detection

    DEFF Research Database (Denmark)

    Storm, Ida Marie Lindhardt Drejer; Rasmussen, Peter Have; Strobel, B.W.

    2008-01-01

    Ergot alkaloids are mycotoxins that are undesirable contaminants of cereal products, particularly rye. A method was developed employing clean-up by cation-exchange solid-phase extraction, separation by high-performance liquid chromatography under alkaline conditions and fluorescence detection....... It is capable of separating and quantifying both C8-isomers of ergocornine, alpha-ergocryptine, ergocristine, ergonovine, and ergotamine. The average recovery was 61% +/- 10% with limits of detection from 0.2 to 1.1 mu g kg(-1). Twenty-four unknown rye flour samples from Danish mills contained on average 46 mu...... g kg(-1) with a maximum content of 234 mu g kg(-1). The most common ergot alkaloids were ergotamine and alpha-ergocryptine including their C8-isomers. A total of 54% of the ergot alkaloids were detected as C(8)-S isomers....

  1. Effect of temperature and pH value on cation exchange performance of a natural clay for selective (Cu2þ, Co2þ) removal:Equilibrium, sorption and kinetics

    Institute of Scientific and Technical Information of China (English)

    Ramzi Chalghaf; Walid Oueslati; Marwa Ammar; Hafsia Ben Rhaiem; Abdesslem Ben Haj Amara

    2013-01-01

    This work aims at investigating the strain effect, created by varying pH solution and continuous heating cycle, on the cation exchange process in the case of Na-rich montmorillonite sample in contact with bi-ionic solution with variable concentration, saturated respectively by Co2þ and Cu2þ cations. The ionic exchange process is characterized using XRD analysis obtained through the comparison of experimental XRD patterns with calculated ones, which allowed us to determine several structural parameters related to the nature, abundance, size, position and organization of exchangeable cation and water molecule in the interlamellar space along the cn axis. Indeed, the proposed theoretical models, for the stressed samples, show that the structure presents an interstratified hydration character and proves the coexistence of more than two ‘‘crystallite’’ specie in the structure. The perturbation types have an obvious effect on the selective exchange process for all stressed samples, where the interlayer space is characterized by the coexistence of more one exchangeable cation.

  2. Review of the thermal stability and cation exchange properties of the zeolite minerals clinoptilolite, mordenite, and analcime; applications to radioactive waste isolation in silicic tuff

    Energy Technology Data Exchange (ETDEWEB)

    Smyth, J.R.; Caporuscio, F.A.

    1981-06-01

    Silicic tuffs of the southern Great Basin and basalts of the Columbia River Plateau are under investigation as potential host rocks for high- and intermediate-level radioactive wastes. Nonwelded and partially welded tuffs may contain major amounts (> 50%) of the zeolite minerals clinoptilolite, mordenite, and analcime. Densely welded tuffs and some basalt flows may contain clinoptilolite as fracture filling that limits the permeability of these rocks. The cation exchange properties of these zeolite minerals allow them to pose a formidable natural barrier to the migration of cationic species of various radionuclides in aqueous solutions. However, these minerals are unstable at elevated temperatures and at low water-vapor pressures and may break down either by reversible dehydration or by irreversible mineralogical reactions. All the breakdown reactions occurring at increased temperature involve a net volume reduction and evolution of fluids. Thus, they may provide a pathway (shrinkage fractures) and a driving force (fluid pressure) for release of radionuclides to the biosphere. These reactions may be avoided by keeping zeolite-bearing horizons saturated with water and below about 85{sup 0}C. This may restrict allowable gross thermal loadings in waste repositories in volcanic rocks.

  3. Hydrogeochemical evolution of confined groundwater in northeastern Osaka Basin, Japan: estimation of confined groundwater flux based on a cation exchange mass balance method

    Energy Technology Data Exchange (ETDEWEB)

    Yamanaka, Masaru [Department of Geosystem Sciences, College of Humanities and Sciences, Nihon University, Setagaya-ku, Tokyo 156-8550 (Japan)]. E-mail: yamanaka@chs.nihon-u.ac.jp; Nakano, Takanori [Research Institute for Humanity and Nature, Kamigyo-ku, Kyoto 602-0878 (Japan); Tase, Norio [Institute of Geoscience, University of Tsukuba, Tsukuba, Ibaraki 305-8571 (Japan)

    2005-02-01

    A confined aquifer system has developed in argillaceous marine and freshwater sediments of Pliocene-Holocene age in the northeastern Osaka Basin (NEOB) in central Japan. The shallow groundwater (<100 m) in the system is recharged in a northern hilly to mountainous area with dominantly Ca-HCO{sub 3} type water, which changes as it flows toward the SW to Mg-HCO{sub 3} type and then to Na-HCO{sub 3} type water. Comparison of the chemical and Sr isotopic compositions of the groundwater with those of the bulk and exchangeable components of the underground sediments indicates that elements leached from the sediments contribute negligibly to the NEOB aquifer system. Moreover, model calculations show that contributions of paleo-seawater in the deep horizon and of river water at the surface are not major factors of chemical change of the groundwater. Instead, the zonal pattern of the HCO{sub 3}-dominant groundwater is caused by the loss of Ca{sup 2+} from the water as it is exchanged for Mg{sup 2+} in clays, followed by loss of Mg + Ca as they are exchanged for Na + K in clays between the Ca-HCO{sub 3} type recharge water and the exchangeable cations in the clay layers, which were initially enriched in Na{sup +}. Part of this process was reproduced in a chromatographic experiment in which Na type water with high {sup 87}Sr/{sup 86}Sr was obtained from Mg type water with low {sup 87}Sr/{sup 86}Sr by passing it through marine clay packed in a column. The flux of recharge water into the confined aquifer system according to this chromatographic model is estimated to be 0.99 mm/day, which is compatible with the average recharge flux to unconfined groundwater in Japan (1 mm/day)

  4. A two-layer ONIOM study of thiophene cracking catalyzed by proton- and cation-exchanged FAU zeolite.

    Science.gov (United States)

    Sun, Yingxin; Mao, Xinfeng; Pei, Supeng

    2016-02-01

    A two-layer ONIOM study on the hydrodesulfurization mechanism of thiophene in H-FAU and M-FAU (M = Li(+), Na(+), and K(+)) has been carried out. The calculated results reveal that in H-FAU, for a unimolecular mechanism, the rate-determining step is hydrogenation of alkoxide intermediate. The assistance of H2O and H2S molecules does not reduce the difficulty of the C-S bond cracking step more effectively. A bimolecular hydrodesulfurization mechanism is more favorable due to the lower activation barriers. The rate-determining step is the formation of 2-methylthiophene, not the C-S bond cracking of thiophene. Moreover, the ring opening of thiophene is much easier to occur than the desulfurization step. A careful analysis of energetics indicates that H2S, propene, and methyl thiophene are the major products for the hydrodesulfurization process of thiophene over H-FAU zeolite, in good agreement with experimental findings. In M-FAU zeolites, both unimolecular and bimolecular cracking processes are difficult to occur because of the high energy barriers. Compared to the case on H-FAU, the metal cations on M-FAU increase the difficulty of occurrence of bimolecular polymerization and subsequent C-S bond cracking steps. Graphical abstract Hydrodesulfurization process of thiophene can take place in H-FAU zeolite. Two different mechanisms, unimolecular and bimolecular ones, have been proposed and evaluated in detail. The bimolecular mechanism is more favorable due to lower activation barrier as described in the picture above. Our calculated data indicate that H2S, propene, and methylthiophene are the major products, in good agreement with experimental observations. The effect of metal cations on the reaction mechanism is also investigated in this work.

  5. Cation exchanged and impregnated Ti-pillared clays for selective catalytic reduction of NO{sub x} by propylene

    Energy Technology Data Exchange (ETDEWEB)

    Valverde, J.L.; De Lucas, A.; Sanchez, P.; Dorado, F.; Romero, A. [Facultad de Quimicas, Departamento de Ingenieria Quimica, Universidad Castilla-La Mancha, 13004 Ciudad Real (Spain)

    2003-06-20

    Ti-pillared interlayer clay (PILC)-based catalysts ion exchanged with Cu, Ni and Fe were prepared and used for the selective catalytic reduction of NO{sub x} using propylene as the reducing agent. The influence of the metal loading in the SCR activity was studied. Likewise, catalytic activity of Cu-ion exchanged samples was compared to that of Cu-ones. In both cases, the catalytic activity increased with increasing metal loading, reaching a maximum of NO{sub x} conversion, and then decreased at higher loading. The maximum of NO{sub x} conversion was achieved in each set of catalysts for the samples NiTi-3.4, FeTi-8.0 and CuTi-7.4. Ti-PILCs-ion exchanged with Cu was the most active catalyst for the SCR of NO{sub x} by propylene. H{sub 2}-TPR results showed that Ni{sup 2+} in Ti-PILC-based catalysts was harder to reduce than Cu{sup 2+} in the same material. It was observed that, as the Cu content is increased, CuO and isolated Cu{sup 2+} species became easier to reduce in ion exchanged samples. Likewise, it was also noted that the relative H{sub 2} consumption decreased with the Cu content, due to a lower accessibility of H{sub 2} to the metal. It can be verified a correlation between NO{sub x} conversion and the H{sub 2} consumption for the Cu{sup 2+} -> Cu{sup +} reduction process, reaching the maximum for the sample CuTi-7.4. Finally, it was observed that the presence of 10% water in the feed inhibited the SCR of NO activity of this catalyst. However, this effect was completely reversible following the removal of water from the gas stream.

  6. Preparation and characterization of electrically conducting polypyrrole Sn(IV phosphate cation-exchanger and its application as Mn(II ion selective membrane electrode

    Directory of Open Access Journals (Sweden)

    A.A. Khan

    2011-10-01

    Full Text Available Polypyrrole Sn(IV phosphate, an organic–inorganic composite cation-exchanger was synthesized via sol-gel mixing of an organic polymer, polypyrrole, into the matrices of the inorganic precipitate of Sn(IV phosphate. The physico-chemical properties of the material were determined using Atomic Absorption Spectrometry (AAS, CHN elemental analysis (inductively coupled plasma mass spectrometry, ICP-MS, UV–VIS spectrophotometry, FTIR (Fourier Transform Infra-Red, SEM (Scanning Electron Microscopy, TGA–DTA (Thermogravimetric Analysis–Differential Thermal Analysis, and XRD (X-ray diffraction. Ion-exchange behavior was observed to characterize the material. On the basis of distribution studies, the material was found to be highly selective for toxic heavy metal ion Mn2+. Due to its selective nature, the material was used as an electroactive component for the construction of an ion-selective membrane electrode. The proposed electrode shows fairly good discrimination of mercury ion over several other inorganic ions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations for Mn(II in water.

  7. Preparation of high-capacity, weak anion-exchange membranes by surface-initiated atom transfer radical polymerization of poly(glycidyl methacrylate) and subsequent derivatization with diethylamine

    Science.gov (United States)

    Qian, Xiaolei; Fan, Hua; Wang, Chaozhan; Wei, Yinmao

    2013-04-01

    Ion-exchange membrane is of importance for the development of membrane chromatography. In this work, a high-capacity anion-exchange membrane was prepared by grafting of glycidyl methacrylate (GMA) onto the surface of regenerated cellulose (RC) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequent derivatization with diethylamine. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to characterize changes in the chemical functionality, surface topography and pore morphology of the modified membranes. The static capacity of the prepared anion-exchange membrane was evaluated with bovine serum albumin (BSA) as a model protein. The results indicated that the anion-exchange membrane which could reach a maximum capacity of 96 mg/mL for static adsorption possesses a higher adsorption capacity, and the adsorption capacity increases with the polymerization time. The effect of pH and salt concentration confirmed that the adsorption of BSA followed ion-exchange mechanism. The established method would have potential application in the preparation of anion-exchange membrane.

  8. Use of Cation Exchange Resins for Production of U{sub 3}O{sub 8} Suitable for the Al-U{sub 3}O{sub 8} Powder Metallurgy Process

    Energy Technology Data Exchange (ETDEWEB)

    Mosley, W.C.

    2001-09-17

    This report describes the production of U{sub 3}O{sub 8} powders from three types of cation exchange resins: Dowex 50W, a strong acid, sulfonate resin; AG MP-50, a macroporous form of sulfonate resin; and Bio-Rex 70, a weak acid, carboxylic resin.

  9. EXCHANGE

    Energy Technology Data Exchange (ETDEWEB)

    Boltz, J.C. (ed.)

    1992-09-01

    EXCHANGE is published monthly by the Idaho National Engineering Laboratory (INEL), a multidisciplinary facility operated for the US Department of Energy (DOE). The purpose of EXCHANGE is to inform computer users about about recent changes and innovations in both the mainframe and personal computer environments and how these changes can affect work being performed at DOE facilities.

  10. Coating of nanoparticles on cryogel surface and subsequent double-modification for enhanced ion-exchange capacity of protein.

    Science.gov (United States)

    Tao, Shi-Peng; Wang, Chuan; Sun, Yan

    2014-09-12

    A novel composite cryogel monolith was developed by coating poly(glycidyl methacrylate) nanoparticles (NPs) onto the pore wall surface of poly(acrylamide) cryogel. The NPs-coated column was double-modified with poly(ethylenimine) (PEI) and diethylaminoethyl in sequence. Scanning electron microscopy revealed the dense coating of the NPs on the cryogel surface, but the NPs-coating did not result in distinct changes of the column porosity and permeability. The rough pore wall surface and extended polymer chains offered more binding sites, so the dynamic binding capacity of the composite cryogel bed for bovine serum albumin reached 11.7mg/mL bed volume at a flow rate of 6cm/min, which was 4.2 times higher than that of the cryogel bed modified with PEI without coating NPs (2.8mg/mL). The binding capacity as well as column efficiency decreased only slightly with increasing flow rate from 0.6 to 12cm/min. The results indicated that the strategy of NPs-coating incorporating with double ion-exchanger modifications is promising for enhancing cryogel capacities, and the novel material would be useful for high-speed protein chromatography.

  11. Squalamine, a novel cationic steroid, specifically inhibits the brush-border Na+/H+ exchanger isoform NHE3.

    Science.gov (United States)

    Akhter, S; Nath, S K; Tse, C M; Williams, J; Zasloff, M; Donowitz, M

    1999-01-01

    Squalamine, an endogenous molecule found in the liver and other tissues of Squalus acanthias, has antibiotic properties and causes changes in endothelial cell shape. The latter suggested that its potential targets might include transport proteins that control cell volume or cell shape. The effect of purified squalamine was examined on cloned Na+/H+ exchanger isoforms NHE1, NHE2, and NHE3 stably transfected in PS120 fibroblasts. Squalamine (1-h pretreatment) decreased the maximal velocity of rabbit NHE3 in a concentration-dependent manner (13, 47, and 57% inhibition with 3, 5, and 7 micrograms/ml, respectively) and also increased K'[H+]i. Squalamine did not affect rabbit NHE1 or NHE2 function. The inhibitory effect of squalamine was 1) time dependent, with no effect of immediate addition and maximum effect with 1 h of exposure, and 2) fully reversible. Squalamine pretreatment of the ileum for 60 min inhibited brush-border membrane vesicle Na+/H+ activity by 51%. Further investigation into the mechanism of squalamine's effects showed that squalamine required the COOH-terminal 76 amino acids of NHE3. Squalamine had no cytotoxic effect at the concentrations studied, as indicated by monitoring lactate dehydrogenase release. These results indicate that squalamine 1) is a specific inhibitor of the brush-border NHE isoform NHE3 and not NHE1 or NHE2, 2) acts in a nontoxic and fully reversible manner, and 3) has a delayed effect, indicating that it may influence brush-border Na+/H+ exchanger function indirectly, through an intracellular signaling pathway or by acting as an intracellular modulator.

  12. Catalysis in a Cage: Condition-Dependent Speciation and Dynamics of Exchanged Cu Cations in SSZ-13 Zeolites.

    Science.gov (United States)

    Paolucci, Christopher; Parekh, Atish A; Khurana, Ishant; Di Iorio, John R; Li, Hui; Albarracin Caballero, Jonatan D; Shih, Arthur J; Anggara, Trunojoyo; Delgass, W Nicholas; Miller, Jeffrey T; Ribeiro, Fabio H; Gounder, Rajamani; Schneider, William F

    2016-05-11

    The relationships among the macroscopic compositional parameters of a Cu-exchanged SSZ-13 zeolite catalyst, the types and numbers of Cu active sites, and activity for the selective catalytic reduction (SCR) of NOx with NH3 are established through experimental interrogation and computational analysis of materials across the catalyst composition space. Density functional theory, stochastic models, and experimental characterizations demonstrate that within the synthesis protocols applied here and across Si:Al ratios, the volumetric density of six-membered-rings (6MR) containing two Al (2Al sites) is consistent with a random Al siting in the SSZ-13 lattice subject to Löwenstein's rule. Further, exchanged Cu(II) ions first populate these 2Al sites before populating remaining unpaired, or 1Al, sites as Cu(II)OH. These sites are distinguished and enumerated ex situ through vibrational and X-ray absorption spectroscopies (XAS) and chemical titrations. In situ and operando XAS follow Cu oxidation state and coordination environment as a function of environmental conditions including low-temperature (473 K) SCR catalysis and are rationalized through first-principles thermodynamics and ab initio molecular dynamics. Experiment and theory together reveal that the Cu sites respond sensitively to exposure conditions, and in particular that Cu species are solvated and mobilized by NH3 under SCR conditions. While Cu sites are spectroscopically and chemically distinct away from these conditions, they exhibit similar turnover rates, apparent activation energies and apparent reaction orders at the SCR conditions, even on zeolite frameworks other than SSZ13.

  13. PLUTONIUM LOADING CAPACITY OF REILLEX HPQ ANION EXCHANGE COLUMN - AFS-2 PLUTONIUM FLOWSHEET FOR MOX

    Energy Technology Data Exchange (ETDEWEB)

    Kyser, E.; King, W.; O' Rourke, P.

    2012-07-26

    Radioactive plutonium (Pu) anion exchange column experiments using scaled HB-Line designs were performed to investigate the dependence of column loading performance on the feed composition in the H-Canyon dissolution process for plutonium oxide (PuO{sub 2}) product shipped to the Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF). These loading experiments show that a representative feed solution containing {approx}5 g Pu/L can be loaded onto Reillex{trademark} HPQ resin from solutions containing 8 M total nitrate and 0.1 M KF provided that the F is complexed with Al to an [Al]/[F] molar ratio range of 1.5-2.0. Lower concentrations of total nitrate and [Al]/[F] molar ratios may still have acceptable performance but were not tested in this study. Loading and washing Pu losses should be relatively low (<1%) for resin loading of up to 60 g Pu/L. Loading above 60 g Pu/L resin is possible, but Pu wash losses will increase such that 10-20% of the additional Pu fed may not be retained by the resin as the resin loading approaches 80 g Pu/L resin.

  14. Evaluation of D113 cation exchange resin for the removal of Eu(Ⅲ) from aqueous solution

    Institute of Scientific and Technical Information of China (English)

    XIONG

    2010-01-01

    Batch adsorption experiments were conducted for the adsorption of Eu(Ⅲ) ions from aqueous solution by D113 resin.The results indicated that D113 resin could adsorb Eu(Ⅲ)ion effectively from aqueous solution.The adsorption was strongly dependent on pH of the medium with enhanced adsorption as the pH turned from 3.50 to 7.00 and the optimal adsorption condition was in HAc-NaAc medium with pH value of 6.50.The maximum uptake capacity of Eu(Ⅲ) ions was 290.9 mg/g D113 at 298 K,at an initial pH value of 6.50.The overall adsorption process was best described by Lagergren-first-order kinetics.When Freundlich and Langmuir isotherms were tested,the latter had a better fit with the experimental data.The thermodynamic parameters such as free energy (AG) which were all negative,indicated that the adsorption of Eu(Ⅲ) ions onto D113 resin was spontaneous and the positive value of enthalpy (△H) showed that the adsorption was endothermic in nature.Thomas model was applied to experimental column data to determine the characteristic parameters of column useful for process design.Furthermore,Eu(Ⅲ) could be eluted by using 3.0 mol/L HCI solution and the D113 resin could be regenerated and reused.

  15. Use of potassium-form cation-exchange resin as a conductimetric enhancer in ion-exclusion chromatography of aliphatic carboxylic acids.

    Science.gov (United States)

    Iwata, Tomotaka; Mori, Masanobu; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2009-09-15

    In this study, a cation-exchange resin (CEX) of the K(+)-form, i.e., an enhancer resin, is used as a postcolumn conductimetric enhancer in the ion-exclusion chromatography of aliphatic carboxylic acids. The enhancer resin is filled in the switching valve of an ion chromatograph; this valve is usually used as a suppressor valve in ion-exchange chromatography. An aliphatic carboxylic acid (e.g., CH(3)COOH) separated by a weakly acidic CEX column of the H(+)-form converts into that of the K(+)-form (e.g., CH(3)COOK) by passing through the enhancer resin. In contrast, the background conductivity decreases because a strong acid (e.g., HNO(3)) with a higher conductimetric response in an eluent converts into a salt (e.g., KNO(3)) with a lower conductimetric response. Since the pH of the eluent containing the resin enhancer increases from 3.27 to 5.85, the enhancer accelerates the dissociations of analyte acids. Consequently, peak heights and peak areas of aliphatic carboxylic acids (e.g., acetic acid, propionic acid, butyric acid, and valeric acid) with the enhancer resin are 6.3-8.0 times higher and 7.2-9.2 times larger, respectively, than those without the enhancer resin. Calibrations of peak areas for injected analytes are linear in the concentration range of 0.01-1.0mM. The detection limits (signal-to-noise ratio=3) range from 0.10 microM to 0.39 microM in this system, as opposed to those in the range of 0.24-7.1 microM in the separation column alone. The developed system is successfully applied to the determination of aliphatic carboxylic acids in a chicken droppings sample.

  16. Heterogeneity of the electron exchange capacity of kitchen waste compost-derived humic acids based on fluorescence components.

    Science.gov (United States)

    Yuan, Ying; Tan, Wen-Bing; He, Xiao-Song; Xi, Bei-Dou; Gao, Ru-Tai; Zhang, Hui; Dang, Qiu-Ling; Li, Dan

    2016-11-01

    Composting is widely used for recycling of kitchen waste to improve soil properties, which is mainly attributed to the nutrient and structural functions of compost-derived humic acids (HAs). However, the redox properties of compost-derived HAs are not fully explored. Here, a unique framework is employed to investigate the electron exchange capacity (EEC) of HAs during kitchen waste composting. Most components of compost-derived HAs hold EEC, but nearly two-thirds of them are found to be easily destroyed by Shewanella oneidensis MR-1 and thus result in an EEC lower than the electron - donating capacity in compost-derived HAs. Fortunately, a refractory component also existed within compost-derived HAs and could serve as a stable and effective electron shuttle to promote the MR-1 involved in Fe(III) reduction, and its EEC was significantly correlated with the aromaticity and the amount of quinones. Nevertheless, with the increase of composting time, the EEC of the refractory component did not show an increasing trend. These results implied that there was an optimal composting time to maximize the production of HAs with more refractory and redox molecules. Recognition of the heterogeneity of EEC of the compost-derived HAs enables an efficient utilization of the composts for a variety of environmental applications. Graphical abstract Microbial reduction of compost-derived HAs.

  17. Changing surface–atmosphere energy exchange and refreezing capacity of the lower accumulation area, west Greenland

    Directory of Open Access Journals (Sweden)

    C. Charalampidis

    2015-05-01

    Full Text Available We present five years (2009–2013 of automatic weather station measurements from the lower accumulation area (1840 m a.s.l. of the ice sheet in the Kangerlussuaq region, western Greenland. Here, the summers of 2010 and 2012 were both exceptionally warm, but only 2012 resulted in a strongly negative surface mass budget (SMB and surface meltwater runoff. The observed runoff was due to a large ice fraction in the upper 10 m of firn that prevented meltwater from percolating to available pore volume below. Analysis reveals a relatively low 2012 summer albedo of ~0.7 as meltwater was present at the surface. Consequently, during the 2012 melt season the surface absorbed 29% (213 MJ m-2 more solar radiation than the average of all other years. A surface energy balance model is used to evaluate the seasonal and interannual variability of all surface energy fluxes. The model reproduces the observed melt rates as well as the SMB for each season. A sensitivity test reveals that 71% of the additional solar radiation in 2012 was used for melt, corresponding to 36% (0.64 m of the 2012 surface lowering. The remaining 1.14 m was primarily due to the high atmospheric temperatures up to +2.6 °C daily average, indicating that 2012 would have been a negative SMB year at this site even without the melt-albedo feedback. Longer time series of SMB, regional temperature and remotely sensed albedo (MODIS show that 2012 was the first strongly negative SMB year with the lowest albedo at this elevation on record. The warm conditions of the last years resulted in enhanced melt and reduction of the refreezing capacity at the lower accumulation area. If high temperatures continue the current lower accumulation area will turn into a region with superimposed ice in coming years.

  18. Changing surface-atmosphere energy exchange and refreezing capacity of the lower accumulation area, West Greenland

    Science.gov (United States)

    Charalampidis, C.; van As, D.; Box, J. E.; van den Broeke, M. R.; Colgan, W. T.; Doyle, S. H.; Hubbard, A. L.; MacFerrin, M.; Machguth, H.; Smeets, C. J. P. P.

    2015-11-01

    We present 5 years (2009-2013) of automatic weather station measurements from the lower accumulation area (1840 m a.s.l. - above sea level) of the Greenland ice sheet in the Kangerlussuaq region. Here, the summers of 2010 and 2012 were both exceptionally warm, but only 2012 resulted in a strongly negative surface mass budget (SMB) and surface meltwater run-off. The observed run-off was due to a large ice fraction in the upper 10 m of firn that prevented meltwater from percolating to available pore volume below. Analysis reveals an anomalously low 2012 summer-averaged albedo of 0.71 (typically ~ 0.78), as meltwater was present at the ice sheet surface. Consequently, during the 2012 melt season, the ice sheet surface absorbed 28 % (213 MJ m-2) more solar radiation than the average of all other years. A surface energy balance model is used to evaluate the seasonal and interannual variability of all surface energy fluxes. The model reproduces the observed melt rates as well as the SMB for each season. A sensitivity analysis reveals that 71 % of the additional solar radiation in 2012 was used for melt, corresponding to 36 % (0.64 m) of the 2012 surface lowering. The remaining 64 % (1.14 m) of surface lowering resulted from high atmospheric temperatures, up to a +2.6 °C daily average, indicating that 2012 would have been a negative SMB year at this site even without the melt-albedo feedback. Longer time series of SMB, regional temperature, and remotely sensed albedo (MODIS) show that 2012 was the first strongly negative SMB year, with the lowest albedo, at this elevation on record. The warm conditions of recent years have resulted in enhanced melt and reduction of the refreezing capacity in the lower accumulation area. If high temperatures continue, the current lower accumulation area will turn into a region with superimposed ice in coming years.

  19. Selective and Accurate Determination Method of Propofol in Human Plasma by Mixed-Mode Cation Exchange Cartridge and GC-MS.

    Science.gov (United States)

    Pyo, Jae Sung

    2016-01-01

    A gas chromatography-mass spectrometry (GC-MS) method for the determination of propofol in human plasma has been developed and validated. Propofol was extracted from human plasma by using mixed-mode cation exchange/reversed-phase (MCX) cartridges. As propofol easily volatilizes during concentration, 100% methanol was injected directly into GC-MS to elute propofol. Despite avoiding concentration process of the eluted solution, lower limit of quantization (LLOQ) of propofol was 25 ng/mL. The validated method exhibited good linearity (R (2) = 0.9989) with accuracy and precision -5.8%~11.7% and 3.7%~11.6%, respectively. The other validation parameters, recovery and matrix effect, ranged from 96.6% to 99.4% and 95.3% to 101.4%, respectively. Propofol standard was quantified to evaluate possible loss due to the concentration processes, nitrogen gas and centrifugal vacuum. These two concentration processes resulted in notable decrease in the quantity of propofol, signifying avoiding any concentration processes during propofol quantification. Also, to confirm suitability of the developed method, authentic human plasma samples were analyzed. The selective assay method using MCX cartridge and GC-MS facilitated quantification of propofol in plasma sample accurately by preventing any losses due to the concentration processes.

  20. Iminodiacetic acid functionalized cation exchange resin for adsorptive removal of Cr(VI), Cd(II), Ni(II) and Pb(II) from their aqueous solutions.

    Science.gov (United States)

    Misra, R K; Jain, S K; Khatri, P K

    2011-01-30

    Iminodiacetic acid functionality has been introduced on styrene-divinyl benzene co-polymeric beads and characterized by FT-IR in order to develop weak acid based cation exchange resin. This resin was evaluated for the removal of different heavy metal ions namely Cd(II), Cr(VI), Ni(II) and Pb(II) from their aqueous solutions. The results showed greater affinity of resin towards Cr(VI) for which 99.7% removal achieved in optimal conditions following the order Ni(II)>Pb(II)>Cd(II) with 65%, 59% and 28% removal. Experiments were also directed towards kinetic studies of adsorption and found to follow first order reversible kinetic model with the overall rate constants 0.3250, 0.2393, 0.4290 and 0.2968 for Cr(VI), Ni(II), Pb(II) and Cd(II) removal respectively. Detailed studies of Cr(VI) removal has been carried out to see the effect of pH, resin dose and metal ion concentration on adsorption and concluded that complexation enhanced the chromium removal efficacy of resin drastically, which is strongly pH dependent. The findings were also supported by the comparison of FT-IR spectra of neat resin with the chromium-adsorbed resin.

  1. Characteristics of Lipoprotein Peak x Eluted from a Column with the Eluent of High-magnesium Ion Concentration in Lipoprotein Analysis Using the Cation-exchange Chromatography

    Directory of Open Access Journals (Sweden)

    Yuji Hirowatari

    2005-01-01

    Full Text Available The new lipoprotein analysis method using a cation-exchange chromatography, which contains a sulfopropyl-ligand column and two magnesium ion-containing eluents was previously reported. This method can separate serum lipoproteins on the column gel with a magnesium ion concentration gradient and high-density lipoprotein (HDL, low-density lipoprotein (LDL, very-low-density lipoprotein (VLDL and an unspecified lipoprotein peak are eluted in order from the column. We have now characterized the unspecified lipoproteins, designated peak x, which is last eluted from the column with the eluent of high-magnesium ion concentration. The peak x was small size chylomicron fraction with a part of VLDL. Furthermore, the cholesterol values in the peak x were significantly correlated with remnant-like particle (RLP-cholesterol values. The peak x separated from a hyperlipidemic patient included apolipoprotein B-100, B-48, E, A-1 and Cs (C-I, C-II, C-III and its composition of free cholesterol, cholesteryl esters, triglyceride (TG and phospholipids in total lipids were 6, 15, 66 and 13%, respectively. These results suggest that a major part of the lipoprotein peak X may be composed of remnants of chylomicron and VLDL, but it remains to be elucidated.

  2. Analysis of amphetamine-type stimulants and their metabolites in plasma, urine and bile by liquid chromatography with a strong cation-exchange column-tandem mass spectrometry.

    Science.gov (United States)

    Kuwayama, Kenji; Inoue, Hiroyuki; Kanamori, Tatsuyuki; Tsujikawa, Kenji; Miyaguchi, Hajime; Iwata, Yuko T; Miyauchi, Seiji; Kamo, Naoki

    2008-05-01

    The aim of this work was to develop and validate a method for analysing amphetamine-type stimulants (ATSs) and their metabolites in plasma, urine and bile by liquid chromatography with a strong cation-exchange column-tandem mass spectrometry, and to apply it to the pharmacokinetic study of ATSs. 3,4-Methylenedioxymethamphetamine, methamphetamine, ketamine and their main metabolites, 4-hydroxy-3-methoxymethamphetamine, 3,4-methylenedioxyamphetamine, p-hydroxymethamphetamine, amphetamine and norketamine, were simultaneously quantified by the new method (50-5000 ng/ml). The coefficients of variation and the percent deviations for the eight compounds were in the range of 0.2 to 5.3% and -9.4 to +12.8%, respectively. The recoveries were over 90% in all biological samples tested. This method was effective for the separation and the identification of ATSs and their main metabolites having amine moieties in plasma, urine and bile, and was applicable to pharmacokinetic analysis of methamphetamine, ketamine and their main metabolites in biological samples. This analytical method should be useful for the pharmacokinetic analysis of ATSs.

  3. Selective and Accurate Determination Method of Propofol in Human Plasma by Mixed-Mode Cation Exchange Cartridge and GC-MS

    Directory of Open Access Journals (Sweden)

    Jae Sung Pyo

    2016-01-01

    Full Text Available A gas chromatography-mass spectrometry (GC-MS method for the determination of propofol in human plasma has been developed and validated. Propofol was extracted from human plasma by using mixed-mode cation exchange/reversed-phase (MCX cartridges. As propofol easily volatilizes during concentration, 100% methanol was injected directly into GC-MS to elute propofol. Despite avoiding concentration process of the eluted solution, lower limit of quantization (LLOQ of propofol was 25 ng/mL. The validated method exhibited good linearity (R2=0.9989 with accuracy and precision −5.8%~11.7% and 3.7%~11.6%, respectively. The other validation parameters, recovery and matrix effect, ranged from 96.6% to 99.4% and 95.3% to 101.4%, respectively. Propofol standard was quantified to evaluate possible loss due to the concentration processes, nitrogen gas and centrifugal vacuum. These two concentration processes resulted in notable decrease in the quantity of propofol, signifying avoiding any concentration processes during propofol quantification. Also, to confirm suitability of the developed method, authentic human plasma samples were analyzed. The selective assay method using MCX cartridge and GC-MS facilitated quantification of propofol in plasma sample accurately by preventing any losses due to the concentration processes.

  4. Quantitative determination of corticosteroids in bovine milk using mixed-mode polymeric strong cation exchange solid-phase extraction and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Tölgyesi, Adám; Tölgyesi, László; Sharma, Virender K; Sohn, Mary; Fekete, Jeno

    2010-12-01

    A new method was developed to identify and quantify corticosteroids (prednisolone, methylprednisone, flumetasone, dexamethasone, and methylprednisolone) in raw bovine milk by liquid chromatography-tandem mass spectrometry (LC-MS/MS) utilizing mixed-mode polymeric strong cation exchange and reversed-phase (MCX) solid-phase extraction (SPE) to reduce ion effects in a multimode ion (MMI) source. The main advantage of this method over other commonly used methods includes the use of a single SPE cartridge with a low volume for sample preparation and fast separation on the HPLC system with reduced ion suppression. This study is the first to report the determination of methylprednisone, a metabolite of methylprednisolone, in bovine milk. This method was validated in accordance with the European Union (EU) Commission Decision 2002/657/EC. The recoveries vary between 90% and 105%. The within-laboratory reproducibility (precision) is less than 30%. The decision limits and detection capabilities were calculated along with LODs, which ranged from 0.02 to 0.07 microg/kg. The method was further enhanced by its successful adaptation to other LC-MS/MS systems equipped with the newly developed ion source, Agilent Jet Stream (AJS). After optimization of the AJS ion source and MS parameters, even lower LOD values were achieved (0.001-0.006 microg/kg) for the corticosteroids. Analytical results obtained with the AJS were characterized by an enhanced area response and similar noise level comparable to those obtained with conventional orthogonal atmospheric ionization (API).

  5. Double-peak elution profile of a monoclonal antibody in cation exchange chromatography is caused by histidine-protonation-based charge variants.

    Science.gov (United States)

    Luo, Haibin; Cao, Mingyan; Newell, Kelcy; Afdahl, Christopher; Wang, Jihong; Wang, William K; Li, Yuling

    2015-12-11

    We have systemically investigated unusual elution behaviors of an IgG4 (mAb A) in cation exchange chromatography (CEX). This mAb A exhibited two elution peaks under certain conditions when being purified by several strong CEX columns. When either of the two peaks was isolated and re-injected on the same column, the similar pattern was observed again during elution. The protein distribution between the two peaks could be altered by NaCl concentration in the feed, or NaCl concentration in wash buffer, or elution pH, suggesting two pH-associated strong-and-weak binding configurations. The protein distributions under different pH values showed good correlation with protonated/un-protonated fractions of a histidine residue. These results suggest that the double-peak elution profile associates with histidine-protonation-based charge variants. By conducting pepsin digestion, amino-acid specific chemical modifications, peptide mapping, and measuring the effects of elution residence time, a histidine in the variable fragment (Fab) was identified to be the root cause. Besides double-peak pattern, mAb A can also exhibit peak-shouldering or single elution peak on different CEX resins, reflecting different resins' resolving capability on protonated/un-protonated forms. This work characterizes a novel cause for unusual elution behaviors in CEX and also provides alternative avenues of purification development for mAbs with similar behaviors.

  6. Isolation of cross-linked peptides by diagonal strong cation exchange chromatography for protein complex topology studies by peptide fragment fingerprinting from large sequence databases.

    Science.gov (United States)

    Buncherd, Hansuk; Roseboom, Winfried; Ghavim, Behrad; Du, Weina; de Koning, Leo J; de Koster, Chris G; de Jong, Luitzen

    2014-06-27

    Knowledge of spatial proximity of amino acid residues obtained by chemical cross-linking and mass spectrometric analysis provides information about protein folding, protein-protein interactions and topology of macromolecular assemblies. We show that the use of bis(succinimidyl)-3-azidomethyl glutarate as a cross-linker provides a solution for two major analytical problems of cross-link mapping by peptide fragment fingerprinting (PFF) from complex sequence databases, i.e., low abundance of protease-generated target peptides and lack of knowledge of the masses of linked peptides. Tris(carboxyethyl)phosphine (TCEP) reduces the azido group in cross-linked peptides to an amine group in competition with cleavage of an amide bond formed in the cross-link reaction. TCEP-induced reaction products were separated by diagonal strong cation exchange (SCX) from unmodified peptides. The relation between the sum of the masses of the cleavage products and the mass of the parent cross-linked peptide enables determination of the masses of candidate linked peptides. By reversed phase LC-MS/MS analysis of secondary SCX fractions, we identified several intraprotein and interprotein cross-links in a HeLa cell nuclear extract, aided by software tools supporting PFF from the entire human sequence database. The data provide new information about interacting protein domains, among others from assemblies involved in splicing.

  7. Water-Chemistry Evolution and Modeling of Radionuclide Sorption and Cation Exchange during Inundation of Frenchman Flat Playa

    Energy Technology Data Exchange (ETDEWEB)

    Hershey, Ronald; Cablk, Mary; LeFebre, Karen; Fenstermaker, Lynn; Decker, David

    2013-08-01

    dioxide and calcite; dissolution of sodium chloride, gypsum, and composite volcanic glass; and precipitation of composite clay and quartz represented changes in water as it disappeared from the playa. This modeling provided an understanding of the water-soil geochemical environment, which was then used to evaluate the potential mobility of residual radionuclides into the playa soils by water. Because there is no information on the chemical forms of anthropogenic radionuclides in Frenchman Flat playa soil, it was assumed that soil radionuclides go into solution when the playa is inundated. In mobility modeling, a select group of radionuclides were allowed to sorb onto, or exchange with, playa soil minerals to evaluate the likelihood that the radionuclides would be removed from water during playa inundation. Radionuclide mobility modeling suggested that there would be minimal sorption or exchange of several important radionuclides (uranium, cesium, and technetium) with playa minerals such that they may be mobile in water when the playa is inundated and could infiltrate into the subsurface. Mobility modeling also showed that plutonium may be much less mobile because of sorption onto calcite, but the amount of reactive surface area of playa soil calcite is highly uncertain. Plutonium is also known to sorb onto colloidal particles suspended in water, suspended colloidal particles will move with the water, providing a mechanism to redistribute plutonium when Frenchman Flat playa is inundated. Water chemistry, stable isotopes, and geochemical modeling showed that residual radionuclides in Frenchman Flat playa soils could be mobilized in water when the playa is inundated with precipitation. Also, there is potential for these radionuclides to infiltrate into the subsurface with water. As a result of the information obtained both during this study and the conclusions drawn from it, additional data collection, investigation, and modeling are recommended. Specifically: sampling the

  8. Preparation of a novel weak cation exchange/hydrophobic interaction chromatography dual-function polymer-based stationary phase for protein separation using "thiol-ene click chemistry".

    Science.gov (United States)

    Yang, Fan; Bai, Quan; Zhao, Kailou; Gao, Dong; Tian, Lei

    2015-02-01

    A novel dual-function mixed-mode stationary phase based on poly(glycidyl methacrylate-co-ethylene dimethacrylate) microspheres was synthesized by thiol-ene click chemistry and characterized by infrared spectroscopy and elemental analysis. The new system displays both hydrophobic interaction chromatography (HIC) character in a high salt concentration mobile phase, and weak cation exchange (WCX) chromatography character in a low salt concentration mobile phase. It can be used to separate proteins in both ion-exchange chromatography (IEC) mode and HIC mode. The resolution and selectivity of the stationary phase were evaluated in both HIC mode and IEC mode using protein standards. In comparison with the conventional WCX and HIC columns, the results were satisfactory and acceptable. Protein mass and bioactivity recoveries of more than 96% can be achieved in both HIC mode and IEC mode using this column. The results indicate that the novel dual-function mixed-mode column in many cases can replace the use of two individual WCX and HIC columns. In addition, the effects on protein separation of different ligand structures in the dual-function stationary phase and the pH of the mobile phase used were also investigated in detail. The results show that electrostatic interaction of the ligand with proteins must match the hydrophobicity of the ligand, which is an important factor to prepare the dual-function stationary phase. On the basis of this dual-function mixed-mode chromatography column, a new two-dimensional liquid chromatography technology with a single column system was also developed in this study, and was used to renature and purify recombinant human interferon-γ from inclusion bodies. The mass recovery, purity, and specific bioactivity obtained for the purified recombinant human interferon-γ were 87.2%, 92.4%, and 2.8 × 10(7) IU/mg, respectively, in IEC mode, and 83.4%, 95.2%, and 4.3 × 10(7) IU/mg, respectively, in HIC mode. The results indicate that the

  9. Synthesis of cyclohexyl acetate by catalytic action of cation exchange resin%阳离子交换树脂催化合成乙酸环己酯

    Institute of Scientific and Technical Information of China (English)

    董森; 彭胜; 郭学华

    2012-01-01

    Cyclohexyl acetate was synthesized by cyclohexene and acetic acid as starting materials with polystyrene sulfonate cation exchange resin as catalyst. Effects of reaction temperature,reaction time,dosage of catalyst and molar ratio of acetic acid to cyclohexene on the reaction yield were investigated. Results showed that the optimum conditions were identified as follows; amount of cyclohexene 0. 1 mol, molar ratio of acetic acid to cyclohexene 4: 1 .dosage of catalyst 0. 96 g,reaction temperature 90 ℃ ,reaction time 5 h. Under these conditions,the yield of cyclohexyl acetate reaches 83.2%. The catalyst can be used for 5 times without significant yield declining.%以磺化苯乙烯阳离子交换树脂为催化剂,催化环己烯和乙酸反应合成乙酸环己酯,考察了反应温度、反应时间、催化剂用量和原料配比对反应的影响.结果表明,较适宜的反应条件为:环己烯用量为0.1 mol,酸烯摩尔比为4∶1,催化剂用量为0.96g,反应温度为90℃,反应时间为5h.在此条件下酯收率为83.2%,催化剂使用5次仍保持较高活性.

  10. Monoclonal antibody heterogeneity analysis and deamidation monitoring with high-performance cation-exchange chromatofocusing using simple, two component buffer systems.

    Science.gov (United States)

    Kang, Xuezhen; Kutzko, Joseph P; Hayes, Michael L; Frey, Douglas D

    2013-03-29

    The use of either a polyampholyte buffer or a simple buffer system for the high-performance cation-exchange chromatofocusing of monoclonal antibodies is demonstrated for the case where the pH gradient is produced entirely inside the column and with no external mixing of buffers. The simple buffer system used was composed of two buffering species, one which becomes adsorbed onto the column packing and one which does not adsorb, together with an adsorbed ion that does not participate in acid-base equilibrium. The method which employs the simple buffer system is capable of producing a gradual pH gradient in the neutral to acidic pH range that can be adjusted by proper selection of the starting and ending pH values for the gradient as well as the buffering species concentration, pKa, and molecular size. By using this approach, variants of representative monoclonal antibodies with isoelectric points of 7.0 or less were separated with high resolution so that the approach can serve as a complementary alternative to isoelectric focusing for characterizing a monoclonal antibody based on differences in the isoelectric points of the variants present. Because the simple buffer system used eliminates the use of polyampholytes, the method is suitable for antibody heterogeneity analysis coupled with mass spectrometry. The method can also be used at the preparative scale to collect highly purified isoelectric variants of an antibody for further study. To illustrate this, a single isoelectric point variant of a monoclonal antibody was collected and used for a stability study under forced deamidation conditions.

  11. Online coupling of hydrophilic interaction/strong cation exchange/reversed-phase liquid chromatography with porous graphitic carbon liquid chromatography for simultaneous proteomics and N-glycomics analysis.

    Science.gov (United States)

    Zhao, Yun; Law, Henry C H; Zhang, Zaijun; Lam, Herman C; Quan, Quan; Li, Guohui; Chu, Ivan K

    2015-10-09

    In this study we developed a fully automated three-dimensional (3D) liquid chromatography methodology-comprising hydrophilic interaction separation as the first dimension, strong cation exchange fractionation as the second dimension, and low-pH reversed-phase (RP) separation as the third dimension-in conjunction downstream with additional complementary porous graphitic carbon separation, to capture non-retained hydrophilic analytes, for both shotgun proteomics and N-glycomics analyses. The performance of the 3D system alone was benchmarked through the analysis of the total lysate of Saccharomyces cerevisiae, leading to improved hydrophilic peptide coverage, from which we identified 19% and 24% more proteins and peptides, respectively, relative to those identified from a two-dimensional hydrophilic interaction liquid chromatography and low-pH RP chromatography (HILIC-RP) system over the same mass spectrometric acquisition time; consequently, the 3D platform also provided enhanced proteome and protein coverage. When we applied the integrated technology to analyses of the total lysate of primary cerebellar granule neurons, we characterized a total of 2201 proteins and 16,937 unique peptides for this primary cell line, providing one of its most comprehensive datasets. Our new integrated technology also exhibited excellent performance in the first N-glycomics analysis of cynomolgus monkey plasma; we successfully identified 122 proposed N-glycans and 135 N-glycosylation sites from 122 N-glycoproteins, and confirmed the presence of 38 N-glycolylneuraminic acid-containing N-glycans, a rare occurrence in human plasma, through tandem mass spectrometry for the first time.

  12. Retention of PWR primary coolant trace elements by cation exchange resins during cold shutdown with oxygenation: modelling and experimental results for silver behavior; Retention des elements traces du fluide primaire des REP par les resines echangeuses de cations lors des mises en arret a froid avec oxygenation: modelisation et resultats experimentaux relatifs au comportement de l'argent

    Energy Technology Data Exchange (ETDEWEB)

    Elain, L.; Doury-Berthod, M. [CEA Saclay, INSTN, Institut National des Sciences et Techniques Nucleaires, 91 - Gif-sur-Yvette (France); Genin, J.B. [CEA Cadarache, Dir. de l' Energie Nucleaire (DEN), 13 - Saint-Paul-lez-Durance (France); Berger, M. [Electricite de France (EDF/SEPTEN), 69 - Villeurbanne (France)

    2004-07-01

    In order to minimize the radiochemical impact of the corrosion products on the operation of Pressurized Water Reactors, on-line purification of the primary coolant is carried out. The purification system arranged on the Chemical and Volume Control System is made up of mechanical filters and demineralizers packed with a mixed bed of cation and anion exchange resins. This paper proposes an update on the retention of primary coolant trace elements by the cation exchange resins of the demineralizers during cold shutdowns with oxygenation. The study is first of all devoted to the description of the concentration profiles of the various cation constituents which settle in the demineralizer during purification after oxygenation. For a number of trace elements, localized enrichment zones at the Li{sup +}/Ni(Il) exchange zone are expected to appear in the column. The case of silver is afterwards discussed in detail. Thermodynamic modelling shows that the theoretical retention volume of the metallic element and its degree of enrichment in the column are dependent on the basic composition of the primary coolant and the specific characteristics of the demineralizer cation exchanger. At the Ag{sup +} ion concentration expected in the reactor coolant after oxygenation (between 10{sup -8} mol.L{sup -1} and 10{sup -6} mol.L{sup -1}), the breakthrough of silver should be near-simultaneous with that of nickel. The experimental results, obtained in the laboratory and with a 'Mini-CVCS' pilot instrumentation recently used during the cold shutdown of Tricastin Unit 2,900 MWe PWR NPP, confirm the validity of these theoretical forecasts and enable new hypotheses to be advanced for explaining silver release from a demineralizer. (authors)

  13. 邻氯苯乙烯-二乙烯基苯强酸性阳离子交换树脂的合成工艺%SYNTHESIS TECHNOLOGY OF o-CHLOROSTYRENE-DIVINYLBENZENE STRONGLY ACIDIC CATION EXCHANGE RESIN

    Institute of Scientific and Technical Information of China (English)

    陈亮; 孙富安; 何明阳; 佟春雨; 张海涛; 陈群

    2012-01-01

    o-chlorostyrene and divinylbenzene occurred suspension copolymerization could obtain high quality copolymer beads. The effects of water-oil ratio, dispersants, assist dispersants and other factors were studied. The optimum reaction conditions: water-oil ratio was from 3:1 to 4:1; poly vinyl alcohol, gelatin, secondary dispersants and electrolyte were respectively 0.1%, 1.0%, 0.5% and 10% ratio of water, the heating rate should be controlled at 20℃/h during the critical period of 40~80℃. Beads sulfonated at 80~110℃ by oleum could be made into strongly acidic cation exchange resin. The exchange capacity was more than 4mmol/g and the synthesis technology of resin has been optimized.%以邻氯苯乙烯和二乙烯基苯为原料制备了邻氯苯乙烯-二乙烯基苯强酸性阳离子交换树脂,考察了水油比、分散剂、助分散剂等因素对合成树脂的影响.研究表明,该树脂的合成最佳工艺条件为:水油比3:1~4:1,聚乙烯醇与明胶分别为水相质量的0.1%和1.0%,助分散剂为水相质量的0.5%,电解质为水相质量的10%,在40~80℃的成球关键期控制升温速率为20℃/h,在80~110℃以发烟硫酸辅助磺化,得到交换量大于4mmol/g的树脂,优化了该树脂的合成工艺.

  14. New inorganic (an)ion exchangers with a higher affinity for arsenate and a competitive removal capacity towards fluoride, bromate, bromide, selenate, selenite, arsenite and borate

    KAUST Repository

    Chubar, Natalia

    2011-12-01

    Highly selective materials and effective technologies are needed to meet the increasingly stronger drinking water standards for targeted ionic species. Inorganic ion exchangers based on individual and mixed-metal hydrous oxides (or mixed adsorbents that contain inorganic ion exchangers in their composition) are adsorptive materials that are capable of lowering the concentrations of anionic contaminants, such as H 2AsO 4 -, H 3AsO 3, F -, Br -, BrO 3 -, HSeO 4 -, HSeO 3 - and H 3BO 3, to 10 μg/L or less. To achieve a higher selectivity towards arsenate, a new ion exchanger based on Mg-Al hydrous oxides was developed by a novel, cost-effective and environmentally friendly synthesis method via a non-traditional (alkoxide-free) sol-gel approach. The exceptional adsorptive capacity of the Mg-Al hydrous oxides towards H 2AsO 4 - (up to 200 mg[As]/gdw) is due to the high affinity of this sorbent towards arsenate (steep equilibrium isotherms) and its fast adsorption kinetics. Because of the mesoporous (as determined by N 2 adsorption and SEM) and layered (as determined by XRD and FTIR) structure of the ion-exchange material as well as the abundance of anion exchange sites (as determined by XPS and potentiometric titration) on its surface the material demonstrated very competitive (or very high) removal capacity towards other targeted anions, including fluoride, bromide, bromate, selenate, selenite, and borate. © 2011 IWA Publishing.

  15. Mercury(II) removal from aqueous solutions and wastewaters using a novel cation exchanger derived from coconut coir pith and its recovery

    Energy Technology Data Exchange (ETDEWEB)

    Anirudhan, T.S. [Department of Chemistry, University of Kerala, Kariavattom, Trivandrum 695581 (India)], E-mail: tsani@rediffmail.com; Divya, L.; Ramachandran, M. [Department of Chemistry, University of Kerala, Kariavattom, Trivandrum 695581 (India)

    2008-09-15

    A new adsorbent (PGCP-COOH) having carboxylate functional group at the chain end was synthesized by grafting poly(hydroxyethylmethacrylate) onto coconut coir pith, CP (a coir industry-based lignocellulosic residue), using potassium peroxydisulphate as an initiator and in the presence of N,N'-methylenebisacrylamide as a cross-linking agent. The adsorbent was characterized with the help of infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and potentiometric titrations. The ability of PGCP-COOH to remove Hg(II) from aqueous solutions was assessed using batch adsorption technique under kinetic and equilibrium conditions. Adsorbent exhibits very high adsorption potential for Hg(II) and more than 99.0% removal was achieved in the pH range 5.5-8.0. Adsorption process was found to follow first-order-reversible kinetics. An increase of ionic strength of the medium caused a decrease in metal removal, indicating the occurrence of outer-sphere surface complex mechanism. The equilibrium data were fitted well by the Freundlich isotherm model (R{sup 2} = 0.99; {chi}{sup 2} 1.81). The removal efficiency was tested using chlor-alkali industry wastewater. Adsorption isotherm experiments were also conducted for comparison using a commercial carboxylate-functionalized ion exchanger, Ceralite IRC-50. Regeneration experiments were tried for four cycles and results indicate a capacity loss of <9.0%.

  16. Mercury(II) removal from aqueous solutions and wastewaters using a novel cation exchanger derived from coconut coir pith and its recovery.

    Science.gov (United States)

    Anirudhan, T S; Divya, L; Ramachandran, M

    2008-09-15

    A new adsorbent (PGCP-COOH) having carboxylate functional group at the chain end was synthesized by grafting poly(hydroxyethylmethacrylate) onto coconut coir pith, CP (a coir industry-based lignocellulosic residue), using potassium peroxydisulphate as an initiator and in the presence of N,N'-methylenebisacrylamide as a cross-linking agent. The adsorbent was characterized with the help of infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and potentiometric titrations. The ability of PGCP-COOH to remove Hg(II) from aqueous solutions was assessed using batch adsorption technique under kinetic and equilibrium conditions. Adsorbent exhibits very high adsorption potential for Hg(II) and more than 99.0% removal was achieved in the pH range 5.5-8.0. Adsorption process was found to follow first-order-reversible kinetics. An increase of ionic strength of the medium caused a decrease in metal removal, indicating the occurrence of outer-sphere surface complex mechanism. The equilibrium data were fitted well by the Freundlich isotherm model (R(2)=0.99; chi(2)=1.81). The removal efficiency was tested using chlor-alkali industry wastewater. Adsorption isotherm experiments were also conducted for comparison using a commercial carboxylate-functionalized ion exchanger, Ceralite IRC-50. Regeneration experiments were tried for four cycles and results indicate a capacity loss of <9.0%.

  17. Use of a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin column and propionic acid as an eluent in ion-exclusion/adsorption chromatography of aliphatic carboxylic acids and ethanol in food samples.

    Science.gov (United States)

    Mori, Masanobu; Hironaga, Takahiro; Kajiwara, Hiroe; Nakatani, Nobutake; Kozaki, Daisuke; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2011-01-01

    We developed an ion-exclusion/adsorption chromatography (IEAC) method employing a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin (PS-WCX) column with propionic acid as the eluent for the simultaneous determination of multivalent aliphatic carboxylic acids and ethanol in food samples. The PS-WCX column well resolved mono-, di-, and trivalent carboxylic acids in the acidic eluent. Propionic acid as the eluent gave a higher signal-to-noise ratio, and enabled sensitive conductimetric detection of analyte acids. We found the optimal separation condition to be the combination of a PS-WCX column and 20-mM propionic acid. Practical applicability of the developed method was confirmed by using a short precolumn with a strongly acidic cation-exchange resin in the H(+)-form connected before the separation column; this was to remove cations from food samples by converting them to hydrogen ions. Consequently, common carboxylic acids and ethanol in beer, wine, and soy sauce were successfully separated by the developed method.

  18. 阳离子交换树脂催化水解大豆糖蜜的研究%Hydrolysis of soy molasses catalyzed by cation exchange resin

    Institute of Scientific and Technical Information of China (English)

    郭紫光; 张永忠

    2011-01-01

    Strong acid styrene cation exchange resin was used to catalyze the hydrolysis of soy molasses.Through single factor and orthogonal experiments, the best conditions were determined as follows: ratio of liquid to solid 3: 1, time 120 min, temperature 60 ℃, concentration of substrate 0.2 g/mL. After hydrolysis under the optimum conditions, the ratio of reducing sugar to total sugar was 0.91, reducing sugar yield was 36.85% and reducing sugar content reached 368.46 mg/g, which was 4. 4 times higher than that before hydrolysis ( 83.93 mg/g). When the molasses was hydrolyzed at the optimal conditions, the reducing sugar yield of the resin catalysis method was almost the same with that of the acid catalysis method, but the resin method avoided the high temperature and low pH, and the resin method had the advantages of easy operation and less wastewater emissions.%采用强酸性苯乙烯系阳离子交换树脂催化水解大豆糖蜜.通过单因素及正交试验得到优化条件为:水解时间120 min,水解温度60℃,液固比3:1,底物质量浓度0.2 g/mL.水解后还原糖与总糖比率达到0.91,还原糖得率为36.85%,还原糖含量达到368.46 mg/g,比水解前的83.93 mg/g提高了3.4倍.与传统酸催化法对比得知,分别在最优条件下水解大豆糖蜜,还原糖得率相差无几,但树脂法避免了高温,pH低,操作简便,废水排放量减少.

  19. Influence of anodic surface treatment of activated carbon on adsorption and ion exchange properties

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.J.; Kim, K.D.

    1999-10-01

    The effect of anodic surface treatment of activated carbon on adsorption and ion exchange characteristics was investigated in the condition of 35 wt% NaOH electrolyte for 60 s. The acid and base values were determined by a titration technique, and surface and pore structures were studied in terms of BET volumetric measurement with N{sub 2} adsorption. The ion exchange capacity of the anodized activated carbons was characterized by a dry weight capacity technique. It was observed that an increase in current intensity leads to an increase in the surface functional groups of activated carbons, resulting in increasing pH, acid-base values, and anion-cation exchange capacities, without significant change of surface and pore structures (i.e., specific surface area, total pore volume, micropore volume, and average pore diameter). Also, anodically treated activated carbons are more effectively evaluated on the base value or cation exchange capacity than on the oppose properties in this electrolytic system.

  20. Simultaneous determination of iodide and iodate in povidone iodine solution by ion chromatography with homemade and exchange capacity controllable columns and column-switching technique.

    Science.gov (United States)

    Huang, Zhongping; Zhu, Zuoyi; Subhani, Qamar; Yan, Wenwu; Guo, Weiqiang; Zhu, Yan

    2012-08-17

    A simple ion chromatographic method for simultaneous detection of iodide and iodate in a single running was proposed, with columns packed with homemade functionalized polystyrene-divinylbenzene (PS-DVB) resins and column-switching technique. Homemade resins were functionalized with controllable amounts of quaternary ammonium groups. The low-capacity anion-exchange column and high-capacity anion-exchange column were prepared, due to the resins having different exchange capacities. With this method, iodide and iodate in povidone iodine solution were detected simultaneously in a short time with iodide being eluted off first. A series of standard solutions consisting of target anions of various concentrations from 0.01 mg/L to 100 mg/L were analyzed. Each anion exhibited satisfactory linearity, with correlation coefficient r ≥ 0.9990. The detection limits (LODs) for iodide and iodate obtained by injecting 100 μL of sample were 5.66 and 14.83 μg/L (S/N=3), respectively. A spiking study was performed with satisfactory recoveries between 101.2% and 100.6% for iodide and iodate.

  1. The elution of erbium from a cation exchanger bed by means of the N-hydroxyethyl-ethylene-diamine triacetic acid; Mecanismo de la elucion del erbio en un cambiador cationico con el acido n-hidroxietil-etilen-diamono-triacetico

    Energy Technology Data Exchange (ETDEWEB)

    Amer Amezaga, S.

    1963-07-01

    A physicochemical study of the phenomena resulting when erbium is eluted from a cation-exchanger bed at a steady by means of the N-hydroxyethyl-ethylene-diamine-triacetic acid (HEDTA) is made. Two different retaining beds are used, a hydrogen bed, in which no ammonium passes through, and a zinc bed, which leaks ammonium ion. Good agreement between experimental and calculated values by using the equations deduced for the concentrations of the main species has been achieved, with errors around 1-2% in most of the experiments. (Author) 69 refs.

  2. A Novel Ion-exchange Method for the Synthesis of Nano-SnO/micro-C Hybrid Structure as High Capacity Anode Material in Lithium Ion Batteries

    Institute of Scientific and Technical Information of China (English)

    Zhi Tan; Zhenhua Sun; Qi Guo; Haihua Wang; Dangsheng Su

    2013-01-01

    A novel and simple ion-exchange method was developed for the synthesis of nano-SnO/micro-C hybrid structure.The structure of the as prepared nano-SnO/micro-C was directly revealed by scanning electron microscopy (SEM)and transmission electron microscopy (TEM).SnO particles with the size about 25 nm were well confined in amorphous carbon microparticles.Carbon matrix in micrometer scale not only acts as a protective buffer for the SnO nanoparticles during the battery cycling processes,but also avoids the shortcomings of nanostructures,such as low tap density and potential safety threats.Electrochemical behaviors of the nano-SnO/micro-C were tested as anode material in lithium ion batteries.The initial reversible capacity is 508 mA h g-1,and the reversible capacity after 60 cycles is 511 mA h g-1,indicating good capacity retention ability.

  3. Cation diffusion in the natural zeolite clinoptilolite

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, A.; White, K.J. [Science Research Institute, Chemistry Division, Cockcroft Building, University of Salford, Salford (United Kingdom)

    1999-12-14

    The natural zeolite clinoptilolite is mined commercially in many parts of the world. It is a selective exchanger for the ammonium cation and this has prompted its use in waste water treatment, swimming pools and in fish farming. It is also used to scavenge radioisotopes in nuclear waste clean-up. Further potential uses for clinoptilolite are in soil amendment and remediation. The work described herein provides thermodynamic data on cation exchange processes in clinoptilolite involving the NH{sub 4}, Na, K, Ca, and Mg cations. The data includes estimates of interdiffusion coefficients together with free energies, entropies and energies of activation for the cation exchanges studied. Suggestions are made as to the mechanisms of cation-exchanges involved.

  4. Effect of soil disturbance on pedotransfer function development for field capacity

    NARCIS (Netherlands)

    Bell, M.A.; Keulen, van H.

    1996-01-01

    The increasing use of simulation models for design and analysis of land use management options has meant an increased need for detailed soil data. When such data are not available, pedotransfer functions (PTFs) can be used to estimate soil properties such as cation exchange capacity (CEC) and field

  5. Actual cation exchange capacity of agricultural soils and its relationship with pH and content of organic carbon and clay

    NARCIS (Netherlands)

    Erp, van P.J.; Houba, V.J.G.; Beusichem, van M.L.

    2001-01-01

    For the set up of a multinutrient 0.01 M calcium chloride (CaCl2) soil testing program a conversion from conventional soil testing programs to a CaCl2 program has been proposed in literature. Such conversion should be based on the relationship between test values of the conventional method and the C

  6. Retention of tannin-C is associated with decreased soluble-N and increased cation exchange capacity in a broad range of soils

    Science.gov (United States)

    Phenolic plant compounds, called tannins, can be retained by soil and affect nutrient cycling but have been studied in only a few soils. Soils (0-10 cm) from locations across the United States and Canada were treated with water (Control) or solutions containing procyanidin, catechin, tannic acid, ß-...

  7. The influence of hydrogen- and cation-underpotential deposition on oxide-mediated Pt dissolution in proton-exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seokkoo [Texas Materials Institute and Center for Electrochemistry, University of Texas at Austin, University Station, C2200 Austin, TX 78712-0292 (United States); Meyers, Jeremy P., E-mail: jeremypmeyers@austin.utexas.edu [Texas Materials Institute and Center for Electrochemistry, University of Texas at Austin, University Station, C2200 Austin, TX 78712-0292 (United States)

    2011-10-01

    Highlights: > Pt dissolution has a maximum value around E{sub L} = 0.5-0.6 V vs. RHE at CV, SW experiments. > The addition of Zn cation (5 mM) in acid solution increase Pt dissolution rate on the region E{sub L} < 0.2 V at E{sub H} = 1.6 V. > Pt dissolution is accelerated by convection flow at over 1.2 V vs. RHE. > The amount of Pt dissolution during Pt oxide reduction reaction is measured by RRDE experiment. - Abstract: In order to fully understand the influence of a lower potential limit on platinum dissolution and the likely mechanism for mass and surface-area loss under potential cycling conditions, the dissolution of a Pt catalyst in a N{sub 2}-saturated 0.5 M H{sub 2}SO{sub 4} solution was examined using an electrochemical quartz nanobalance (EQCN) flow cell, a rotating ring-disk electrode (RRDE) and inductively coupled plasma mass spectroscopy (ICP-MS). Due to the observation that cycling to a lower potential limit, which coincides with the hydrogen under-potential (H{sub UPD}) region, results in a decrease in the dissolution rate, cations capable of interfering with the hydrogen UPD process (Zn{sup 2+}, Li{sup +}, Na{sup +}, K{sup +}, and Cd{sup 2+}) were introduced to the solution. Larger rates of mass loss were observed in the presence of these cations during the cycling process in the UPD region, despite apparently negligible effects on the behavior with more positive lower potential limits or on oxide formation and stripping. It was found that the quantity of soluble Pt species produced during the electrochemical reduction of PtO{sub 2} was proportional to the charge associated with oxide stripping at the disk electrode during the RRDE experiment.

  8. Capacities of Clay Fraction of a Latosol to Retain Cations and Anions as Inferred from the Wien Effect in Soil Suspensions

    Institute of Scientific and Technical Information of China (English)

    LI CHENGBAO; S. P. FRIEDMAN; ZHAO ANZHEN

    2003-01-01

    Suspensions of a latosol with a clay concentration of 30 g kg-1 were prepared from electrodialyzed clay fractions, less than 2 μm in diameter, five nitrate solutions with a concentration of 1 × 10-4/z mol L-1,where z is the valence, and five sodium salt solutions with a concentration of 3.3 × 10-5/z mol L-1. The direct current (DC) electrical conductivities (ECs) of the colloidal suspensions were measured at a constant temperature of 25 ℃, using a newly established method of measuring the Wien effect in soil suspensions at field strengths ranging from 13.5 to 150 kV cm-1, to determine their electrical conductivity-field strength relationships and to infer the order of the bonding strength (retaining force) between soil particles and various ions. The measurements with the latosol suspensions in NaNO3, KNO3, Ca(NO3)2, Mg(NO3)2 and Zn(NO3)2 solutions resulted in increments of the suspension ECs, △ECs, of 7.9, 5.0, 7.1, 7.0 and 5.8μS cm-1,respectively, when the applied field strength increased from 14.5 to 142 kV cm-1. As for the suspensions in NaNO3, NaCl, Na2SO4, Na3PO4 and Na3AsO4 solutions, the △ECs were 6.2, 5.3, 4.1, 4.0 and 3.7μS cm-1,respectively, when the applied field strength increased from 13.5 to 90 kV cm-1. Thus, it can be deduced that the retaining forces of the clay fraction of the latosol for the cations were in the descending order K+ >Zn2+ > Mg2+ ≥ Ca2+ > Na+, and for the anions in the descending order H2AsO-4 > H2PO-4 ≥ SO42- > Gl- > NO-3.

  9. Hydrolyzed Poly(acrylonitrile) Electrospun Ion-Exchange Fibers.

    Science.gov (United States)

    Jassal, Manisha; Bhowmick, Sankha; Sengupta, Sukalyan; Patra, Prabir K; Walker, Douglas I

    2014-06-01

    A potential ion-exchange material was developed from poly(acrylonitrile) fibers that were prepared by electrospinning followed by alkaline hydrolysis (to convert the nitrile group to the carboxylate functional group). Characterization studies performed on this material using X-ray photoelectron spectroscopy, scanning electron microscopy, Fourier-Transform infra-red spectroscopy, and ion chromatography confirmed the presence of ion-exchange functional group (carboxylate). Optimum hydrolysis conditions resulted in an ion-exchange capacity of 2.39 meq/g. Ion-exchange fibers were used in a packed-bed column to selectively remove heavy-metal cation from the background of a benign, competing cation at a much higher concentration. The material can be efficiently regenerated and used for multiple cycles of exhaustion and regeneration.

  10. Influence of zirconium hydrophosphate nanoparticles on porous structure and sorption capacity of the composites based on ion exchange resin

    OpenAIRE

    Dzyazko, Yuliya; Ponomarova, Ludmila; Volfkovich, Yurii; Tsirina, Valentina; Sosenkin, Valentin; Nikolska, Nadiya; Belyakov, Volodimir

    2016-01-01

    Evolution of swelling of gel-like strongly acidic resin and organic-inorganic composites based on this ionexchanger was investigated. Non-aggregated nanoparticles of zirconium hydrophosphate were found to provide size invariability of the polymer pores, which contain functional groups (up to 20 nm), the nanoparticle aggregates squeeze these pores (down to 3 nm). Owing to this, the nanocomposite shows higher break-through capacity during removal of Ni2+ from water, than the sample modified onl...

  11. Alkaline solution neutralization capacity of soil.

    Science.gov (United States)

    Asakura, Hiroshi; Sakanakura, Hirofumi; Matsuto, Toshihiko

    2010-10-01

    Alkaline eluate from municipal solid waste (MSW) incineration residue deposited in landfill alkalizes waste and soil layers. From the viewpoint of accelerating stability and preventing heavy metal elution, pH of the landfill layer (waste and daily cover soil) should be controlled. On the other hand, pH of leachate from existing MSW landfill sites is usually approximately neutral. One of the reasons is that daily cover soil can neutralize alkaline solution containing Ca(2+) as cation. However, in landfill layer where various types of wastes and reactions should be taken into consideration, the ability to neutralize alkaline solutions other than Ca(OH)(2) by soil should be evaluated. In this study, the neutralization capacities of various types of soils were measured using Ca(OH)(2) and NaOH solutions. Each soil used in this study showed approximately the same capacity to neutralize both alkaline solutions of Ca(OH)(2) and NaOH. The cation exchange capacity was less than 30% of the maximum alkali neutralization capacity obtained by the titration test. The mechanism of neutralization by the pH-dependent charge can explain the same neutralization capacities of the soils. Although further investigation on the neutralization capacity of the soils for alkaline substances other than NaOH is required, daily cover soil could serve as a buffer zone for alkaline leachates containing Ca(OH)(2) or other alkaline substances.

  12. Fluphenazine hydrochloride radical cation assay: A new, rapid and precise method to determine in vitro total antioxidant capacity of fruit extracts

    Institute of Scientific and Technical Information of China (English)

    Muhammad Nadeem Asghar; Qadeer Alam; Sharoon Augusten

    2012-01-01

    A new procedure based on generation and subsequent reduction of orange-colored fluphenazine hydrochloride radical (FPH·+)is presented for the screening of total antioxidant capacity (TAC) of various fruit matrices.The FPH·+ was obtained by mixing fluphenazine hydrochloride with persulfate (final concentration 2 mmol/L and 0.05 mmmol/L,respectively) in 3 mol/L H2SO4 with constant shaking for 5 min.The solution formed showed maximum absorption as 0.8 ± 0.02 at 500 nm in first-order derivative spectrum.The percent inhibition of the solution increased linearly on addition of increasing mounts of standard antioxidants i.e.,ascorbic acid etc.The TACs of sample citrus juices were calculated in terms of ascorbic acid equivalents (AAEs) by comparing their inhibition curves with that of ascorbic acid.Comparison of AAE values of different commercial orange juices using the newly developed FPH·+ assay and the well-known ABTS/K2S2O8 and DMPD/FeCl3 assays indicated the precision and comparable sensitivity of the method.The proposed procedure is quick,economical,and more precise and gives results comparable to contemporary assays.

  13. Detachable strong cation exchange monolith, integrated with capillary zone electrophoresis and coupled with pH gradient elution, produces improved sensitivity and numbers of peptide identifications during bottom-up analysis of complex proteomes.

    Science.gov (United States)

    Zhang, Zhenbin; Yan, Xiaojing; Sun, Liangliang; Zhu, Guijie; Dovichi, Norman J

    2015-04-21

    A detachable sulfonate-silica hybrid strong cation-exchange monolith was synthesized in a fused silica capillary, and used for solid phase extraction with online pH gradient elution during capillary zone electrophoresis-tandem mass spectrometry (CZE-MS/MS) proteomic analysis. Tryptic digests were prepared in 50 mM formic acid and loaded onto the strong cation-exchange monolith. Fractions were eluted using a series of buffers with lower concentration but higher pH values than the 50 mM formic acid background electrolyte. This combination of elution and background electrolytes results in both sample stacking and formation of a dynamic pH junction and allows use of relatively large elution buffer volumes while maintaining reasonable peak efficiency and resolution. A series of five pH bumps were applied to elute E. coli tryptic peptides from the monolith, followed by analysis using CZE coupled to an LTQ-Orbitrap Velos mass spectrometer; 799 protein groups and 3381 peptides were identified from 50 ng of the digest in a 2.5 h analysis, which approaches the identification rate for this organism that was obtained with an Orbitrap Fusion. We attribute the improved numbers of peptide and protein identifications to the efficient fractionation by the online pH gradient elution, which decreased the complexity of the sample in each elution step and improved the signal intensity of low abundance peptides. We also performed a comparative analysis using a nanoACQUITY UltraPerformance LCH system. Similar numbers of protein and peptide identifications were produced by the two methods. Protein identifications showed significant overlap between the two methods, whereas peptide identifications were complementary.

  14. Long-term effects of high nitrogen loads on cation and carbon riverine export in agricultural catchments.

    Science.gov (United States)

    Aquilina, Luc; Poszwa, Anne; Walter, Christian; Vergnaud, Virginie; Pierson-Wickmann, Anne-Catherine; Ruiz, Laurent

    2012-09-01

    The intensification of agriculture in recent decades has resulted in extremely high nitrogen inputs to ecosystems. One effect has been H(+) release through NH(4)(+) oxidation in soils, which increases rock weathering and leads to acidification processes such as base-cation leaching from the soil exchange complex. This study investigated the evolution of cation concentrations over the past 50 years in rivers from the Armorican crystalline shield (Brittany, western France). On a regional scale, acidification has resulted in increased base-cation riverine exports (Ca(2+), Mg(2+), Na(+), K(+)) correlated with the increased NO(3)(-) concentration. The estimated cation increase is 0.7 mmol(+)/L for Ca(2+) + Mg(2+) and 0.85 mmol(+)/L for total cations. According to mass balance, cation loss represents >30% of the base-cation exchange capacity of soils. Long-term acidification thus contributes to a decline in soil productivity. Estimates of the total organic nitrogen annually produced worldwide indicate that acidification may also constitute an additional carbon source in crystalline catchments if compensated by liming practices.

  15. Cation exchange for mercury and cadmium of xanthated, sulfonated, activated and non-treated subbituminous coal, commercial activated carbon and commercial synthetic resin:effect of pre-oxidation on xanthation of subbituminous coal

    Institute of Scientific and Technical Information of China (English)

    Lewis M. Gomez; Fredy Colpas-Castillo; Roberto Fernandez-Maestre

    2014-01-01

    A subbituminous coal was oxidized with air at 150 ?C on a fixed bed for 4 h and xanthated with carbon disulfide in a basic solution, at 30 or 5–10 ?C. This xanthated coal was evaluated for the removal of Hg2? and Cd2? from 7,000 mg/L aqueous solutions; metal concentrations were determined by atomic absorption spectrometry. The ion exchange of the xanthated coal was compared against those of the original subbituminous coal, a sulfonated subbituminous coal, activated carbon, commercial activated carbon, and commercial synthetic resin. The commercial synthetic resin showed the highest exchange capacity (concentration factor 98%) followed by the xanthated coal (concentration factor 96%). The retention of cadmium on the sulfonated subbituminous coal was lower (exchange capacity 0.56 meq/g) than that of xanthated coals (1.85 ± 0.09 meq/g). Our xanthated coal showed a better Cd2? removal (81%against 15%) than a non preoxidized 40-h-xanthated coal, which shows that oxidation of coal increased the amount of oxygenated groups which enhanced xanthation.

  16. 离子交换型缓蚀填料在防腐蚀涂层中的应用Ⅰ阳离子交换型填料%Application of Ion-exchange Compounds as Corrosion Inhibiting Pigments to Organic Anticorrosion Coatings Ⅰ Cation-exchange Pigments

    Institute of Scientific and Technical Information of China (English)

    吴俊升; 肖葵; 李欣荣; 董超芳; 李晓刚

    2011-01-01

    铬酸盐等重金属类缓蚀性颜填料会对环境造成严重的污染,未来该类有害物质在防腐蚀涂层中的应用将被禁止。新型的离子交换型填料因其具有可同时释放缓蚀性离子和吸附固定侵蚀性离子(H+、Cl-、SO24-等)的双重功效,被认为是替代传统重金属类颜填料的理想材料。本文对Zn2+、Ce3+、Ca2+等缓蚀性阳离子改性膨润土、氧化硅、分子筛等新型离子交换型缓蚀填料在有机防腐蚀涂层中的应用进行了综述。%It is well documented that chromate pigments and other heavy metal compounds must be eliminated from organic anticorrosion coatings due to their toxic nature and carcinogenic effects in the future. The novel ion-exchange pigments can play a double role of absorbing the harmful ions such as H+ ,C1- ,SO24- and releasing the inhibiting ions on contact with aggressive electrolyte invading the coating. The released inhibitors can provide active corrosion protection to the defects in the coating and substrate, on the other hand, the uptake of harmful ions decreases the aggressiveness of the corrosive medium, and thereby reduces the rate of ecorrosion processes. Therefore, such new inhibiting compounds have been developed as the potential alternate materials of the traditional toxic pigments, and have attracted a lot of attention. In this paper, the application of ion-exchange pigments, such as Ce3+ , Znz+ cation-exchanged bentonite, Ca2+ cation-exchanged silica and MoO22+ cation-exchanged zeolite, to organic anticorrosion coatings is reviewed.

  17. Optimal dynamic capacity allocation of HVDC interconnections for cross-border exchange of balancing services in presence of uncertainty

    DEFF Research Database (Denmark)

    Delikaraoglou, Stefanos; Pinson, Pierre; Eriksson, Robert

    2015-01-01

    of the power system depends both on the technical parameters of its components, i.e., generators and transmission infrastructure, as well as on the operational practices that make optimal use of the available assets. This work focuses on alternative market designs that enable sharing of cross-border balancing...... and the uncertainty arising from their partial predictability. Considering that the existing setup of the European electricity markets promotes the spatial coordination of neighbouring power systems only on the day-ahead market stage, regional system operators have to rely mainly on their internal balancing resources...... resources between adjacent power systems through High Voltage Direct Current (HVDC) interconnections which provide increased controllability. In this context, we formulate a stochastic market-clearing algorithm that attains full spatio-temporal integration of reserve capacity, day-ahead and balancing...

  18. Anion exchange membrane

    Science.gov (United States)

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  19. Ion-exchange and hydrophobic interactions affecting selectivity for neutral and charged solutes on three structurally similar agglomerated ion-exchange and mixed-mode stationary phases.

    Science.gov (United States)

    Kazarian, Artaches A; Taylor, Mark R; Haddad, Paul R; Nesterenko, Pavel N; Paull, Brett

    2013-11-25

    The nature and extent of mixed-mode retention mechanisms evident for three structurally related, agglomerated, particle-based stationary phases were evaluated. These three agglomerated phases were Thermo Fisher ScientificIon PacAS11-HC - strong anion exchange, Thermo Fisher Scientific IonPac CS10--strong cation-exchange PS-DVB, and the Thermo Fisher Scientific Acclaim Trinity P1silica-based substrate, which is commercially marketed as a mixed-mode stationary phase. All studied phases can exhibit zwitterionic and hydrophobic properties, which contribute to the retention of charged organic analytes. A systematic approach was devised to investigate the relative ion-exchange capacities and hydrophobicities for each of the three phases, together with the effect of eluent pH upon selectivity, using a specifically selected range of anionic, cationic and neutral aromatic compounds. Investigation of the strong anion-exchange column and the Trinity P1 mixed-mode substrate, in relation to ion-exchange capacity and pH effects, demonstrated similar retention behaviour for both the anionic and ampholytic solutes, as expected from the structurally related phases. Further evaluation revealed that the ion-exchange selectivity of the mixed-mode phase exhibited properties similar to that of the strong anion-exchange column, with secondary cation-exchange selectivity, albeit with medium to high anion-exchange and cation-exchange capacities, allowing selective retention for each of the anionic, cationic and ampholytic solutes. Observed mixed-mode retention upon the examined phases was found to be a sum of anion- and cation-exchange interactions, secondary ion-exchange and hydrophobic interactions, with possible additional hydrogen bonding. Hydrophobic evaluation of the three phases revealed logP values of 0.38-0.48, suggesting low to medium hydrophobicity. These stationary phases were also benchmarked against traditional reversed-phase substrates namely, octadecylsilica YMC-Pac Pro C18

  20. Diffusion capacity of the lung for carbon monoxide - A potential marker of impaired gas exchange or of systemic deconditioning in chronic obstructive lung disease?

    Science.gov (United States)

    Weinreich, Ulla Møller; Thomsen, Lars Pilegaard; Brock, Christina; Karbing, Dan Stieper; Rees, Stephen Edward

    2015-11-01

    Gas exchange impairment is primarily caused by ventilation-perfusion mismatch in chronic obstructive pulmonary disease (COPD), where diffusing capacity of the lungs for carbon monoxide (DLCO) remains the clinical measure. This study investigates whether DLCO: (1) can predict respiratory impairment in COPD, that is, changes in oxygen and carbon dioxide (CO2); (2) is associated with combined risk assessment score for COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) score); and (3) is associated with blood glucose and body mass index (BMI). Fifty patients were included retrospectively. DLCO; arterial blood gas at inspired oxygen (FiO2) = 0.21; oxygen saturation (SpO2) at FiO2 = 0.21 (SpO2 (21)) and FiO2 = 0.15 (SpO2 (15)) were registered. Difference between arterial and end-tidal CO2 (ΔCO2) was calculated. COPD severity was stratified according to GOLD score. The association between DLCO, SpO2, ΔCO2, GOLD score, blood glucose, and BMI was investigated. Multiple regression showed association between DLCO and GOLD score, BMI, and glucose level (R (2) = 0.6, p < 0.0001). Linear and multiple regression showed an association between DLCO and SpO2 (21) (R (2) = 0.3, p = 0.001 and p = 0.03, respectively) without contribution from SpO2 (15) or ΔCO2. A stronger association between DLCO and GOLD score than between DLCO and SpO2 could indicate that DLCO is more descriptive of systemic deconditioning than gas exchange in COPD patients. However, further larger studies are needed. A weaker association is seen between DLCO and SpO2 (21) without contribution from SpO2 (15) and ΔCO2. This could indicate that DLCO is more descriptive of systemic deconditioning than gas exchange in COPD patients. However, further larger studies are needed.

  1. Effects of hydrochloric acid modification on the channel characteristics, composition, surface potential and cation exchange behavior of natural clinoptilolite%盐酸改性对天然斜发沸石孔道特征、成分、表面电位及阳离子交换性能的影响

    Institute of Scientific and Technical Information of China (English)

    霍汉鑫; 林海; 董颖博; 刘泉利; 曹丽霞; 程皝; 汪涵; 傅川

    2015-01-01

    采用不同浓度盐酸对天然斜发沸石进行改性,并系统地研究了改性沸石的孔道特征、化学成分、表面电位及阳离子交换性能的变化.盐酸改性后,沸石晶体结构破坏较小,表面变得疏松粗糙,K+、Na+、Ca2+和Mg2+元素含量均小幅下降;表面负电荷增加,阳离子交换容量减小;比表面积和总孔体积均有所提高,最高分别从原沸石的35.97 m2·g -1和0.0761 m3·g-1提高至64.46 m2·g-1和0.1156 m3·g-1.盐酸改性对沸石微孔、介孔和大孔的分布影响明显.从迟滞回线形状判断沸石孔道类型均为不均匀狭缝型孔道,盐酸改性不会改变沸石孔道类型.%ABSTRACT Natural clinoptilolite was modified by different concentrations of hydrochloric acid. Systemic investigations were performed on the channel characteristics, chemical composition, surface potential, and cation exchange behavior of the modified clinoptilolite. It is found that the surface of the modified clinoptilolite becomes loose and rough, the contents of K+, Na+, Ca2+, and Mg2+ slightly decrease, the surface negative charges increases, and the cation exchange capacity decreases to some extent. The specif-ic surface area and total pore volume are improved and the maximum values of them increase from 35.97 m2·g-1 and 0.0761 m3·g-1 to 64.46 m2·g-1 and 0.1156 m3·g-1 , respectively. The distribution of micropores, mesopores, and macropores is obviously impacted, and the type of zeolite cavities is determined to be uneven slits by the hysteresis loop shape, indicating that this acid modification cannot change zeolite cavities.

  2. Diffusion of an organic cation into root cell walls.

    Science.gov (United States)

    Meychik, N R; Yermakov, I P; Prokoptseva, O S

    2003-07-01

    Uptake of a cationic dye (methylene blue) by isolated root cell walls, roots of whole transpiring seedlings, and excised roots was investigated using 7-day-old seedlings of cucumber, maize, and wheat. The number of ionogenic groups per 1 g dry and wet weight of the root cell walls, their swelling capacity (K(cw)), time-dependence of methylene blue (M(cw)) ion exchange capacity, and diffusion coefficients of the cation diffusion in the polymer matrix of the cell walls (D(cw)) were determined. The M(cw) value depended on pH (or carboxyl group dissociation); it changed in accordance with the number of carboxyl groups per 1 g cell wall dry weight. This parameter decreased in the order: cucumber > wheat > maize. For description of experimental kinetic curves and calculation of cation diffusion coefficients, the equation for ion diffusion into a cylinder of infinite length was used. The chosen model adequately described cation diffusion in cell walls and roots. Diffusion coefficient values for cucumber, wheat, and maize were 3.1*10(-8), 1.3*10(-8), and 8.4*10(-8) cm(2)/sec, respectively. There was a statistically significant linear dependence between K(cw) and D(cw) values, which characterize the same property of the polymer matrix, rigidity of its polymer structure or the degree of cross-linkage or permeability. This also confirms the right choice of the model selected for calculation of methylene blue diffusion coefficients, because K(cw) and D(cw) values were obtained in independent experiments. The coefficients determined for methylene blue diffusion in transpiring seedling roots (D(ts)) and excised roots (D(er)) depended on the plant species. The rate of methylene blue diffusion into the excised roots was either 1.5-fold lower (cucumber) or 3-4-times lower (maize, wheat) than in cell walls. The values of diffusion coefficients in roots of whole seedlings were comparable which those for the cell walls. On the basis of the experimental data and results of calculations

  3. Direct modification of hydrogen/deuterium-terminated diamond particles with polymers to form reversed and strong cation exchange solid phase extraction sorbents.

    Science.gov (United States)

    Yang, Li; Jensen, David S; Vail, Michael A; Dadson, Andrew; Linford, Matthew R

    2010-12-03

    We describe direct polymer attachment to hydrogen and deuterium-terminated diamond (HTD and DTD) surfaces using a radical initiator (di-tert-amyl peroxide, DTAP), a reactive monomer (styrene) and a crosslinking agent (divinylbenzene, DVB) to create polystyrene encapsulated diamond. Chemisorbed polystyrene is sulfonated with sulfuric acid in acetic acid. Surface changes were followed by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and diffuse reflectance Fourier transform infrared spectroscopy (DRIFT). Finally, both polystyrene-modified DTD and sulfonated styrene-modified DTD were used in solid phase extraction (SPE). Percent recovery and column capacity were investigated for both phenyl (polystyrene) and sulfonic acid treated polystyrene SPE columns. These diamond-based SPE supports are stable under basic conditions, which is not the case for silica-based SPE supports.

  4. Hydrogen adsorption over Zeolite-like MOF materials modified by ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Calleja, G.; Botas, J.A.; Orcajo, M.G. [Department of Chemical and Energy Technology, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, 28933 Mostoles, Madrid (Spain); Sanchez-Sanchez, M. [Instituto de Catalisis y Petroleoquimica, CSIC, C/Marie Curie 2, 28049 Madrid (Spain)

    2010-09-15

    Novel porous Zeolite-like metal-organic framework (ZMOF) materials with Rho and Sod topologies are promising adsorbents for hydrogen storage due to their high surface area and, more importantly, to their capacity of being ion-exchanged, potentially changing their affinity for hydrogen. In this work, we have successfully synthesized both Rho and SodZMOF materials, optimizing experimental conditions for scaling-up the procedure already published to produce grams of material. The resultant materials were alkaline-cation-exchanged, widely characterized and finally tested as hydrogen adsorbents. RhoZMOF is converted into an amorphous phase during some of the ion-exchange processes, whereas SodZMOF, whose ion-exchange capacity has not been investigated so far, always maintains its topology for any tested exchange cation and conditions. Additionally, thermogravimetric analyses and thermal treatments followed by in-situ powder X-ray diffraction analysis have evidenced a significantly higher thermal stability of both as-prepared and ion-exchanged SodZMOF materials in comparison to their Rho-structured homologues. Moreover, the thermal stability of the cation-exchanged ZMOF samples improves when methanol is the ion-exchange solvent rather than the reported ethanol-water mixture. Nitrogen and hydrogen adsorption isotherms at 77 K suggested that alkali-exchanged materials have lower affinity for hydrogen than the as-prepared samples compensated by imidazolium ion; however, due to the smaller size of Na{sup +} or Li{sup +} cations, their lower affinity is easily compensated by the inherent increase in surface area and pore volume as exchange degree increases. (author)

  5. Development and characterization of cation exchange sorbent of St - DVB copolymer support for solid-phase extraction%St-DVB基质阳离子交换固相萃取填料的研制及应用

    Institute of Scientific and Technical Information of China (English)

    申书昌; 李媛媛; 柏叶春

    2011-01-01

    以玉米淀粉为分散剂,偶氮二异丁腈 (AIBN)为引发剂,二乙烯基苯(DVB)为交联剂,在在氮气保护下,用悬浮聚合法制备了交联苯乙烯-二乙烯苯(St-DVB )高分子微球,用浓硫酸进行磺化,制成了以St-DVB为基质的阳离子交换固相萃取填料.考察了搅拌速度对交联聚苯乙烯微球粒径大小及分布的影响.分别用TEM,SEM/EDS和傅里叶红外光谱法对填料进行了形貌及结构分析,测定了磺化物的磺化度.自制阳离子交换固相萃取小柱,对水中的莠去津进行了应用试验,考察了性能.%In this paper, used eom-starch as dispersing agent, 2,2-azobisisobutyronitrile as initiator of polymerization, divinyl benzene as cross-linking agent,polystyrene-divinyl benzene microspheres were prepared by suspension polymerization under nitrogen.The polystyrene-divinyl benzene microspheres were sulfonated by concentrated sulfuric acid, the polystyrene-divinyl benzene sulphonic acid material as a cation exchange sorbent for solid phase extraction packing. stirring speed were investigated to cress-linked polystyrene partiele size and distribution. The form , structure and composition of the polystyrene-divinyl benzene and the polystyrene -divinyl benzene sulphonie acid mierospheres were characterized by means of transmission electron mieraseope , scanning electron microscope/energy dispersive X-ray spectrometer and fourier transform infrared spectroscopy measurement respectively the sulfonate sulfonation degree was Determinated by acid-soda titration method. The cation exchange solid phase extraction column made using the self-made and a plastic syringe. The atrazine in water was detected by solid phase extraetion-HPLC

  6. Improving stability of virus-like particles by ion-exchange chromatographic supports with large pore size: advantages of gigaporous media beyond enhanced binding capacity.

    Science.gov (United States)

    Yu, Mengran; Li, Yan; Zhang, Songping; Li, Xiunan; Yang, Yanli; Chen, Yi; Ma, Guanghui; Su, Zhiguo

    2014-02-28

    Limited binding capacity and low recovery of large size multi-subunits virus-like particles (VLPs) in conventional agarose-gel based chromatographic supports with small pores have long been a bottleneck limiting the large scale purification and application of VLPs. In this study, four anion exchange media including DEAE-Sepharose FF (DEAE-FF), DEAE-Capto, gigaporous DEAE-AP-120nm and DEAE-AP-280nm with average pore diameters of 32nm, 20nm, 120nm and 280nm, respectively, were applied for purification of hepatitis B virus surface antigen (HBsAg) VLPs. Pore size effects of media on the VLPs adsorption equilibrium, adsorption kinetics, dynamic binding capacity (DBC), and recovery were investigated in detail. According to the confocal laser scanning microscopy observation, adsorption of the VLPs in DEAE-FF and DEAE-Capto was mostly confined to a thin shell on the outer surface of the beads, leaving the underlying pore space and the binding sites inaccessibly, while the large pores in gigaporous media enabled the VLPs to access to the interior pore spaces by diffusion transport efficiently. Compared to the most widely used DEAE-FF, gigaporous media DEAE-AP-280nm gained about 12.9 times increase in static adsorption capacity, 8.0 times increase in DBC, and 11.4 times increase in effective pore diffusivity. Beyond increasing the binding capacity and enhancing the mass transfer, the gigaporous structure also significantly improved the stability of the VLPs during intensive adsorption-desorption process by lowing the multi-point interaction between the VLPs and binding sites in the pores. At 2.0mg/mL-media loading quantity, about 85.5% VLPs were correctly self-assembled after the chromatography with DEAE-AP-280nm media; oppositely about 85.2% VLPs lost their normal assembly with DEAE-FF due to irreversible disassembly. Comparative investigation was made to study the purifying performance of these four chromatographic media for actual VLPs purification from recombinant

  7. Effect of Clay Mineralogy and Exchangeable Cations on Permeability of Saudi Sandstone Reservoirs Effet de la minéralogie des argiles et des cations échangeables sur la perméabilité des réservoirs gréseux d'Arabie Saoudite

    Directory of Open Access Journals (Sweden)

    Dahab A. S.

    2006-11-01

    Full Text Available Reservoir rocks are susceptible to formation damage during secondary recovery operations due to the particular mineralogical, textural and electrochemical properties of the clay minerals they contain. This damage can be explained by the swelling of indigeneous clays present, resulting in the constricting of pores, or by the dispersion of indigeneous nonswelling particle rearrangements during fluid flow, resulting in the plugging of the pore system, or by a combination of the two. This article describes a laboratory study showing the effect of clay mineralogy on the permeability of actual Saudi sandstone reservoirs during water flooding operations. The study shows that the permeability damage of Saudi sandstone reservoirs depends upon the amount of swelling clays and exchangeable ions as well as on the nature of these ions. Monovalent cations cause more damage than multivalent ones but within the same group of metals, those with smaller atomic mass cause more damage. Les roches réservoirs peuvent être endommagées pendant les opérations de récupération secondaire à cause des propriétés minéralogiques, texturales et électrochimiques particulières des minéraux argileux qu'elles contiennent. Cet endommagement peut s'expliquer, soit par le gonflement des argiles qui conduit à un rétrécissement des pores, soit par la migration de particules non gonflantes pendant l'écoulement des fluides qui entraîne le colmatage des milieux poreux, soit par une combinaison des deux mécanismes. Cet article présente une étude de laboratoire montrant l'effet de la minéralogie des argiles sur la perméabilité des roches réservoirs réelles d'Arabie Saoudite pendant des opérations d'injection d'eau. L'étude montre que l'endommagement de la perméabilité des roches réservoirs d'Arabie Saoudite dépend de la quantité d'argiles gonflantes et d'ions échangeables, ainsi que de la nature de ces ions. Les cations monovalents provoquent plus d

  8.  Pressure-induced Fe↔Cu cationic valence exchange and its structural consequences: High-pressure studies of delafossite CuFeO2

    Science.gov (United States)

    Xu, W. M.; Rozenberg, G. Kh.; Pasternak, M. P.; Kertzer, M.; Kurnosov, A.; Dubrovinsky, L. S.; Pascarelli, S.; Munoz, M.; Vaccari, M.; Hanfland, M.; Jeanloz, R.

    2010-03-01

    The present high-pressure studies of CuFeO2 to 30 GPa using x-ray diffraction, along with F57e Mössbauer and Fe and CuK -edge x-ray absorption spectroscopy methods, reveal a sequence of intricate structural/electronic-magnetic pressure-induced transitions. The low-pressure R3¯m structure (0-18 GPa) is composed of sheets of FeS=5/23+ ions alternating with layers of O-CuS=01+-O dumbbells, the latter oriented along the c axis. This structure is characterized by an unusual positive d(c/a)/dP . At 18 GPa a structural transition takes place to a more isotropic C2/c structure with the O-CuS=01+-O axis tilted 28° from the c axis and with negative d(c/a)/dP . This transition corroborates with the onset of long-range antiferromagnetic order. Starting at ˜23GPa , with an initial volume reduction in ˜|ΔV/V0|=0.16 , the Cu-Fe bands overlap and this leads to a (CuS=01+FeS=5/23+)→(CuS=1/22+FeS=22+) interionic valence exchange in about 1/3 of the C2/c-CuFeO2 at 27 GPa. As a result: (i) the Cu2+-O becomes fourfold coordinated and is in a new crystallographic structure with space group P3¯m , and (ii) the Néel temperature increases above twofold [TN(CuS=1/22+FeS=22+)≈2.2TN(CuS=01+FeS=5/23+)] . This sequence of transitions is reversible with minimal hysteresis.

  9. Bulk derivatization and cation exchange restricted access media-based trap-and-elute liquid chromatography–mass spectrometry method for determination of trace estrogens in serum

    Energy Technology Data Exchange (ETDEWEB)

    Beinhauer, Jana [Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Bian, Liangqiao [Shimadzu Center for Advanced Analytical Chemistry, The University of Texas at Arlington, Arlington, TX (United States); Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); Fan, Hui [Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX (United States); Šebela, Marek [Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Kukula, Maciej [Shimadzu Center for Advanced Analytical Chemistry, The University of Texas at Arlington, Arlington, TX (United States); Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); Barrera, Jose A. [Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); and others

    2015-02-09

    Highlights: • Analysis of estrogens in small volume samples at low parts-per-trillion concentration. • Charged bulk derivatization facilitates on-line ion exchange sample preparation. • On-line WCX restricted access media traps analytes, but not proteins and lipids. • Complete preparation and LC–MS/MS analysis completed in 30 min/sample. - Abstract: Estrone (E1), estradiols (α/β-E2), and estriol (E3) are four major metabolically active estrogens exerting strong biological activities at very low circulating concentrations. This paper reports a sensitive and efficient method with automated, on-line clean-up and detection to determine trace estrogens in a small volume of serum samples using liquid chromatography–electrospray ionization–tandem mass spectrometry directly, without off-line liquid–liquid or solid-phase extraction pretreatments. Serum aliquots (charcoal stripped fetal bovine serum, 100 μL) were spiked with four estrogen standards and their corresponding isotope-labeled internal standards, then bulk derivatized with 2-fluoro-1-methyl-pyridium p-toluenesulfonate (2-FMP) to establish the calibration curves and perform method validation. Calibration was established in the concentration ranges of 5–1000 pg mL{sup −1}, and demonstrated good linearity of R{sup 2} from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL{sup −1}. Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified.

  10. Thermally induced conversion of Mg2+ cation exchanged LTA, FAU, GIS and SOD zeolites: syntheses and characterization of γ-cordierite, a new Mg2Al4Si5O18 polymorph

    Directory of Open Access Journals (Sweden)

    RADOVAN DIMITRIJEVIC

    2007-12-01

    Full Text Available The thermal behaviours of fully Mg2+ cation exchanged LTA, FAU (X and Y species, GIS and SOD zeolites were investigated in the temperature range from ambient to 1400 °C. The initial zeolite frameworks collapsed into amorphous intermediate substances after air heating between 800–850 °C. Prolonged annealing of these products above 850 °C induced recrystallization into sapphirine-like phases (Mg–LTA and Mg–FAUx zeolites and μ-cordierite (Mg–FAUy and Mg–GIS zeolites phases. These phases were unstable during further temperature/time treatment and between 1000–1100 °C, they polymorphously transformed into γ-cordierite, a new Mg2Al4Si5O18 polymorph. γ-Cordierite was formed as a transformation product from the investigated zeolite precursors, except for the Mg–SOD zeolite. Structurally the γ-cordierite phase is a modulated, Mg-stuffed derivative of cristobalite with the approximate composition Mg2Al4Si5O18, which precedes the appearance of α-cordierite. The orthorhombic unit cell dimensions calculated from X-ray powder diffraction pattern are: a = 16.387(7 Å, b = 8.835(4 Å, c = 7.853(3 Å. γ-Cordierite has a narrow range of temperature stability (1100–1200 °C and during prolonged temperature/time treatment, it is polymorphously transformed to the α-cordierite phase.

  11. Spin heat capacity of monolayer and AB-stacked bilayer MoS2 in the presence of exchange magnetic field

    Science.gov (United States)

    Hoi, Bui Dinh; Yarmohammadi, Mohsen; Mirabbaszadeh, Kavoos

    2017-04-01

    Dirac theory and Green's function technique are carried out to compute the spin dependent band structures and corresponding electronic heat capacity (EHC) of monolayer (ML) and AB-stacked bilayer (BL) molybdenum disulfide (MoS2) two-dimensional (2D) crystals. We report the influence of induced exchange magnetic field (EMF) by magnetic insulator substrates on these quantities for both structures. The spin-up (down) subband gaps are shifted with EMF from conduction (valence) band to valence (conduction) band at both Dirac points in the ML because of the spin-orbit coupling (SOC) which leads to a critical EMF in the K point and EHC returns to its initial states for both spins. In the BL case, EMF results split states and the decrease (increase) behavior of spin-up (down) subband gaps has been observed at both K and K‧ valleys which is due to the combined effect of SOC and interlayer coupling. For low and high EMFs, EHC of BL MoS2 does not change for spin-up subbands while increases for spin-down subbands.

  12. Changes in the Vibrational Spectra of Zeolites Due to Sorption of Heavy Metal Cations

    Science.gov (United States)

    Król, M.; Mozgawa, W.; Barczyk, K.; Bajda, T.; Kozanecki, M.

    2013-11-01

    This work presents the results of spectroscopic (MIR and Raman) studies of zeolite structures after immobilization of heavy metal cations from aqueous solutions. The sorption of Ag+, Cu2+, Cd2+, Pb2+, Zn2+, and Cr3+ ions has been conducted on zeolites belonging to different structural groups, i.e., sodium forms of natural chabazite, mordenite, ferrierite, and clinoptilolite, as well as on synthetic zeolite Y. Systematic changes in intensities and positions of the bands corresponding to the characteristic ring vibrations have been observed in the measured spectra. The most visible changes are observed in the FT-IR spectra of the samples in the range of 850-450 cm-1, and in the Raman spectra in the range of 600-250 cm-1. Depending on the zeolite structure, the bands, which can be regarded as a kind of indicator of ion exchange, were indentifi ed. For example, in the case of IR spectra, these bands are at 766, 703, 648, 578, and 506 cm-1 for zeolite Y, at 733 and 560 cm-1 for mordenite, at 675 cm-1 for clinoptilolite, etc. The degree of changes depends on both the type of cation and its concentration in the initial solution. This is connected with the way of binding of metal ions to the zeolite aluminosilicate framework, i.e., a proportion of the ion exchange and chemisorption in the process. Cations mainly undergoing ion exchange, such as Cd2+ or Pb2+, have the greatest impact on the character of the spectra. On the other hand, Cr3+ ions practically do not modify the spectra of zeolites. Results of IR and Raman spectroscopic studies have been compared with those obtained by atomic absorption spectroscopy (AAS), from which the proportion of ion exchange to chemisorption in the process and the effective cation exchange capacity of the individual samples have been estimated.

  13. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation

    Science.gov (United States)

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-01

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  14. 强酸性阳离子交换树脂催化合成乙酰水杨酸的研究%Synthesis of acetylsalicylic acid using strong-acidic cation-exchange resin as catalyst

    Institute of Scientific and Technical Information of China (English)

    赵志刚; 谢志融; 陈靠山

    2012-01-01

    目的:探讨001×7强酸性阳离子交换树脂催化合成乙酰水杨酸的方法和最佳工艺.方法:通过正交试验探讨了乙酸酐与水杨酸的摩尔比、反应时间、催化剂用量和反应温度对乙酰水杨酸产率的影响,并探讨催化剂的催化能力与使用次数的关系.结果:乙酸酐与水杨酸的摩尔比为3:1、催化剂用量为水杨酸质量的14.50%、反应时间120 min、反应温度60 ℃时,乙酰水杨酸产率最高,为77.93%.结论:001×7强酸性苯乙烯系阳离子交换树脂对酯化反应催化效果好,副反应少,对环境污染小,能重复使用,值得大力推广.%Objective:To optimize the technology of synthesizing acetylsalicylic acid using 001 × 7 strong-acidic cation-exchange resin as catalyst . Methods : Orthogonal experiment was performed to examine the effect of molar ratio of reactants,reaction time, dosage of catalyst, and reaction temperature on the yield of product as well as the efficiency and frequencies of the resin recycled and shifted on the synthesis. Results :The optimal reaction conditions were 3:1 (the ratio of acetic anhydride to salicylic acid,n:n),in a dosage of the resin 14. 50% of salicylic acid,for the reaction time of 120 min at temperature of 60 ℃ , which led to a yield of 77.93 % . Conclusion: 001 × 7 strong-acidic cat ion-exchange resin works well on esterification reaction as a environmentally friendly catalyst and is worthy of wider use, for it has efficient activity, less adverse reaction and recyclable advantages.

  15. 强酸阳树脂在过氧化氢中的氧化分解特性研究%Characteristics of oxidation and decomposition of strong acidic cation exchange resin in hydrogen peroxide

    Institute of Scientific and Technical Information of China (English)

    朱志平; 周瑜; 赵永福; 郭小翠

    2012-01-01

    在核电站,SO42-会引起镍基金属的晶间应力腐蚀破裂,对核电站的安全经济运行造成严重危害.为探索核电站SO42-的来源,研究了几种进口阳树脂在H2O2溶液中的动态溶出特性,采用离子色谱仪和TOC仪对溶出液的SO42-、TOC进行测定.研究结果表明,过氧化氢对大孔型和凝胶型树脂的影响不同,且氧化剂浓度越高,对树脂的影响越大,溶出的SO42-也越多;脱磺化速率随着时间推移而降低,而有机物溶出速率变化相对较小.%SO42- may cause intergranular stress corrosion cracking of nickel-based metal in nuclear power stations, resulting in serious hazards to the economically running of the nuclear power stations. To explore the source of SO42-of nuclear power stations, dynamic dissolving characteristics of several kinds of imported cation exchange resins in hydrogen peroxide solution have been researched. The dissolved liquid of S042- ,TOC are determined by ion chro-matography and TOC meter. The results show that the effects of hydrogen peroxide on macro-porous resin and gel-type resin are different. The higher the oxidant concentration is,the higher the influence on resin is,and the more SO42- is dissolved. And it is very likely that the desulfonation rate decreases with time, and the change of dissolving rate of organisms is relatively small.

  16. Development and validation of a UHPLC-MS/MS assay for colistin methanesulphonate (CMS) and colistin in human plasma and urine using weak-cation exchange solid-phase extraction.

    Science.gov (United States)

    Zhao, Miao; Wu, Xiao-Jie; Fan, Ya-Xin; Guo, Bei-Ning; Zhang, Jing

    2016-05-30

    A rapid ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) assay method was developed for determination of CMS and formed colistin in human plasma and urine. After extraction on a 96-well SPE Supra-Clean Weak Cation Exchange (WCX) plate, the eluents were mixed and injected into the UHPLC-MS/MS system directly. A Phonomenex Kinetex XB-C18 analytical column was employed with a mobile phase consisting of solution "A" (acetonitrile:methanol, 1:1, v/v) and solution "B" (0.1% formic acid in water, v/v). The flow rate was 0.4 mL/min with gradient elution over 3.5 min. Ions were detected in ESI positive ion mode and the precursor-product ion pairs were m/z 390.7/101.3 for colistin A, m/z 386.0/101.2 for colistin B, and m/z 402.3/101.2 for polymyxin B1 (IS), respectively. The lower limit of quantification (LLOQ) was 0.0130 and 0.0251 mg/L for colistin A and colistin B in both plasma and urine with accuracy (relative error, %) <± 12.6% and precision (relative standard deviation, %) <± 10.8%. Stability of CMS was demonstrated in biological samples before and during sample treatment, and in the extract. This new analytical method provides high-throughput treatment and optimized quantification of CMS and colistin, which offers a highly efficient tool for the analysis of a large number of clinical samples as well as routine therapeutic drug monitoring.

  17. Research on removal of metal impurities from wet-process phosphoric acid with macroporous strong acid cation exchange resin%大孔阳离子树脂脱除湿法磷酸中阳离子的研究

    Institute of Scientific and Technical Information of China (English)

    熊祥祖; 徐彪; 王威; 杜文; 胡利锋

    2011-01-01

    采用D001大孔强酸性阳离子交换树脂三级处理湿法磷酸中的金属杂质,考察了搅拌速度、温度、树脂用量及反应时间对金属阳离子去除率的影响.结果表明,在搅拌速度为200 r/min、树脂质量磷酸质量为12、反应温度为400 ℃、反应时间为10 min时,效果最好,铁的去除率可达到86.75%、铝的去除率可达到76.13%、镁的去除率可到达40.38%、钙的去除率可到达47.49%.%The removal rate of metal impurities in Wet-Process Phosphoric Acid with D001 macroporous strong acid cation exchange resin was researched.Some important factors which affect the removal rate of metal impurities such as stirring speed, temperature, the mass ratio of resin to phosphoric acid and reaction time were studied respectively.The results show that the removal efficiency of iron,aluminum,magnesium,calcium can be up to 86.75%, 76.13%, 40.38%, 47.49%, respectively, when the stirring speed was 200 r/min, the mass ratio of resin to phosphoric acid was 1:2, the temperature was 40 ℃,the reaction time was 10min.

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

    Science.gov (United States)

    Droge, Steven T J; Goss, Kai-Uwe

    2013-12-17

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

  19. Effect of water pollutants to copper ion removal bv using cation exchange membrane%水中污染物对阳离子交换膜分离去除Cu2+的影响

    Institute of Scientific and Technical Information of China (English)

    谢德华; 施周; 陈世洋

    2012-01-01

    Baesd on Donnan dialysis mechanism, copper ion separation and removing experiments in raw water using exchange membrane was conducted under voltage free condition. The copper ion removing effects of cation exchange membrane cuased by various potential pollutants in raw water such as inorganic particles, organic matters, EDTA acid, ammonia, ferric ion and surfacatant etc, were studied. The results showed that upon addition any one of the above pollutants to raw water, would influence on the copper ions removing effects more or less after a long time operation procedure. To pollutants with no physical and chemical interaction with copper ion and membrane, such as silica and non-ionic surfactant, there were little influences on the copper ion separation of the cation exchange membrane and the Cu2+ removal decreased only by about 4% compared to that of blank control experiments; Cu2+ could be precipitated by ammonia and anionic surfaceactive agent, or adsorbed by humic acid which made the concentration of free Cu2+ in the solution reduce by about 50%; While to pollutants which could form complex compounds with Cu2+, serious effects on Cu2+ removal efficiency were observed. For EDTA acid, ammonia and anionic surfaceactive agent, the Cu2+ removal effects decreased by approximately 100%, 78% and 56% respectively; Cationic surfactants may occupy a lot of space of film render Cu2+ remove difficulty; ferric ion easily hydrolyzed into iron hydroxide colloids in weak acid or neutral solution induced Cu2+ removal effect decreased to certain extend, by about 12% compared to the blank.%基于Donnan dialysis原理,在无外加电压作用下采用阳离子交换膜分离去除原水中的Cu2+,研究原水中可能出现的无机颗粒物,有机物质,EDTA酸、氨水、Fe3+、表面活性剂等对阳离子交换膜分离去除Cu2+效果的影响.研究表明:原水中添加二氧化硅、腐殖酸、EDTA酸、氨水、Fe3+、表面活性剂等物质,在长时间运行后均

  20. Studies on Natural CXN Zeolite:Modification, Framework De-alumination and lon-exchange

    Institute of Scientific and Technical Information of China (English)

    LONG,Ying-Cai(龙英才); XIA,Xiao-Hui(夏晓慧); YANG,Bo(杨波); ZHANG,Ling-Mei(张玲妹); ZHOU,Wei-Zheng(周伟正); GAO,Zhi-Long(曹智龙); LI,Cai-Yun(李彩云)

    2004-01-01

    A natural CXN zeolite (stilbite, type code-STI) discovered in China was modified with NH4+ exchange by using ammonium salt and calcinations (procedure Ⅰ), or with NH4+ exchange followed by treatment with acid (procedure Ⅱ). The coordination state of Si and Al atoms in the framework, the property of ion exchange, and the adsorption of the H-STI zeolite samples prepared by different modification procedure were investigated with XRD,EDX, 29Si and 27Al MAS NMR, Ag+ ion exchange and N2 adsorption. The results of the investigations indicate that different procedure of the modification made variety on the distribution of the framework Si atoms and Al atoms,the content of non-framework aluminum, and the blocking channels and the shielding effect to the positions of the exchangeable cations. The H-STI zeolite prepared by the procedure Ⅱ possesses high ion exchange capacity, open and perfect pore system, and high thermal stability.

  1. Experimental and density functional theory study of the adsorption of N2O on ion-exchanged ZSM-5: part II. The adsorption of N2O on main-group ion-exchanged ZSM-5.

    Science.gov (United States)

    Zhang, Bo; Lu, Yongan; He, Hong; Wang, Jianguo; Zhang, Changbin; Yu, Yunbo; Xue, Li

    2011-01-01

    The adsorption and desorption of N2O on main-group ion-exchanged ZSM-5 was studied using temperature-programmed desorption (TPD) and density functional theory (DFT) calculations. TPD experiments were carried out to determine the desorbed temperature Tmax corresponding to the maximum mass intensity of N2O desorption peak and adsorption capacity of N2O on metal-ion-exchanged ZSM-5s. The results indicated that Tmax followed a sequence of Ba2+ > Ca2+ > Cs+ > K+ > Na+ > Mg2+ and the amount of adsorbed N2O on main-group metal cation followed a sequence of Ba2+ > Mg2+ > Ca2+ > Na+ > K+ > Cs+. The DFT calculations were performed to obtain the adsorption energy (Eads), which represents the strength of the interaction between metal cations and the N-end or O-end of N2O. The calculation results showed that the N-end of the N2O molecule was favorably adsorbed on ion-exchanged ZSM-5, except for Cs-ZSM-5. For alkali metal cations, the Eads of N2O on cations followed the order which was the same to that of Tmax: Cs+ > K+ > Na+. The calculated and experimental results consistently showed that the adsorption performances of alkaline-earth metal cations were better than those of alkali metal cations.

  2. Formation of Zirconium Hydrophosphate Nanoparticles and Their Effect on Sorption of Uranyl Cations

    Science.gov (United States)

    Perlova, Nataliya; Dzyazko, Yuliya; Perlova, Olga; Palchik, Alexey; Sazonova, Valentina

    2017-03-01

    Organic-inorganic ion-exchangers were obtained by incorporation of zirconium hydrophosphate into gel-like strongly acidic polymer matrix by means of precipitation from the solution of zirconium oxychloride with phosphoric acid. The approach for purposeful control of a size of the incorporated particles has been developed based on Ostwald-Freundich equation. This equation has been adapted for precipitation in ion exchange materials. Both single nanoparticles (2-20 nm) and their aggregates were found in the polymer. Regulation of salt or acid concentration allows us to decrease size of the aggregates approximately in 10 times. Smaller particles are formed in the resin, which possess lower exchange capacity. Sorption of U(VI) cations from the solution containing also hydrochloride acid was studied. Exchange capacity of the composites is ≈2 times higher in comparison with the pristine resin. The organic-inorganic sorbents show higher sorption rate despite chemical interaction of sorbed ions with functional groups of the inorganic constituent: the models of reaction of pseudo-first or pseudo-second order can be applied. In general, decreasing in size of incorporated particles provides acceleration of ion exchange. The composites can be regenerated completely, this gives a possibility of their multiple use.

  3. Mineral Separation in a CELSS by Ion-exchange Chromatography

    Science.gov (United States)

    Ballou, E. V.; Spitze, L. A.; Wong, F. W.; Wydeven, T.; Johnson, C. C.

    1982-01-01

    Operational parameters pertinent to ion exchange chromatography separation were identified. The experiments were performed with 9 mm diameter ion exchange columns and conventional column accessories. The cation separation beds were packed with AG 50W-X2 strong acid cation exchange resin in H(+) form and 200-400 dry mesh particle size. The stripper beds used in some experiments were packed with AG 1-XB strong base cation exchange resin in OH(-) form and 200-400 dry mesh particle size.

  4. Chromatographic separation of inorganic ions on thin layers of titanium phosphate ion-exchanger

    Institute of Scientific and Technical Information of China (English)

    Vanik GHOULIPOUR; Moharram SAFARI

    2014-01-01

    The chromatographic behavior of 30 inorganic cations has been studied on thin layers of titanium phosphate ion-exchanger using several aqueous,organic and mixed mobile phases. The separation of one ion from several other ions and also ternary and binary separations have been developed. Some important analytical separations are reported. The effect of pH of the mobile phase on retention factor(Rf)values of the cations in the presence of complex-forming anion along with the separation power of the ion-exchanger were studied. This ion-exchanger exhibits high sorption capacity and varying selectivity towards metal ions and makes it a suitable stationary phase in thin layer chromatography.

  5. Chromatographic separation of inorganic ions on thin layers of titanium phosphate ion-exchanger.

    Science.gov (United States)

    Ghoulipour, Vanik; Safari, Moharram

    2014-12-01

    The chromatographic behavior of 30 inorganic cations has been studied on thin layers of titanium phosphate ion-exchanger using several aqueous, organic and mixed mobile phases. The separation of one ion from several other ions and also ternary and binary separations have been developed. Some important analytical separations are reported. The effect of pH of the mobile phase on retention factor (Rf) values of the cations in the presence of complex-forming anion along with the separation power of the ion-exchanger were studied. This ion-exchanger exhibits high sorption capacity and varying selectivity towards metal ions and makes it a suitable stationaiy phase in thin layer chromatography.

  6. Cationic ruthenium alkylidene catalysts bearing phosphine ligands.

    Science.gov (United States)

    Endo, Koji; Grubbs, Robert H

    2016-02-28

    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bearing bulky phosphine ligands. Simple ligand exchange using silver(i) salts of non-coordinating or weakly coordinating anions provided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported catalysts feature unique geometries caused by ligation of the bulky phosphine ligands. Their activities and selectivities in standard metathesis reactions were also investigated. These cationic ruthenium alkylidene catalysts reported here showed moderate activity and very similar stereoselectivity when compared to the second generation ruthenium dichloride catalyst in ring-closing metathesis, cross metathesis, and ring-opening metathesis polymerization assays.

  7. Hidrólise parcial da superfície do polyethylene terephthalate (PET: transformando um rejeito em um material de troca catiônica para aplicação ambiental Partial hydrolysis of pet surface: transforming a plastic waste into a material with cationic exchange properties for environmental application

    Directory of Open Access Journals (Sweden)

    Marcelo G. Rosmaninho

    2009-01-01

    Full Text Available In this work it is proposed a simple and versatile undergraduate chemical experiment in polymer and environmental technology based on the process of polyethylene terephthalate (PET hydrolysis. Polyethylene terephthalate from post-consume bottles is submitted to a controlled partial hydrolysis which allows the students to follow the reaction by a simple procedure. The students can explore the reaction kinetics, the effect of catalysts and the exposed polyethylene terephthalate surface area on the hydrolysis reaction. The second and innovative part of this experiment is the technological and environmental application of the hydrolyzed polyethylene terephthalate as a material with cation exchange properties. The surface hydrolyzed polyethylene terephthalate can be used as adsorbent for cationic contaminants.

  8. 阳离子交换毛细管整体柱的制备及其在毛细管离子色谱中的应用%Preparation and Application of Cation-exchange Capillary Monolithic Column in Capillary Ion Chromatography

    Institute of Scientific and Technical Information of China (English)

    李晶; 朱岩

    2013-01-01

    Polymer-based cation exchange capillary monolithic column was prepared for capillary ion chromatography (CIC) by radical polymerization in a 320-μm-i. d. fused-silica capillary tube, taking glycidyl methacrylate ( GMA ) as the functional monomer, ethylene dimethacrylate ( EDMA) as the cross-linking agent and in the presence of 1 ,4-butanediol, 1-propanol and water as the porogen solvents and azobisisobutyronitrile (AIBN) as a suitable initiator. Introduction of cation exchange sites was achieved by reacting with Na2SO3. Coupled with the prepared cation exchange capillary monolithic column, a capillary ion chromatography system was constructed with a pump (in μL/min level) , a capillary detection cell and a UV detector, on which more chromatographic characteristics were further studied. With the CIC system, 9 common univalent and divalent cations (Li+ , Na+ , NH4+ , K+ , Cs+ , Mg2+, Ca2+ , Sr2+, Ba2+) were successfully separated and determined by flow rate gradient. Another interesting separation of cations and melamine was also tested on the prepared column.%以甲基丙烯酸缩水甘油酯(GMA)为功能单体,亚乙基二甲基丙烯酸酯(EDMA)为交联剂,偶氮二异丁腈(AIBN)为自由基引发剂,在三元致孔剂(正丙醇,1,4-丁二醇,水)的存在下,在320μm内径的弹性石英毛细管柱内制备得到带有环氧功能基团的聚合物整体柱基质;利用Na2SO3对其改性,制备得到磺酸基型阳离子交换毛细管整体柱.采用微流泵、毛细管检测池和紫外检测器构建了毛细管离子色谱系统,并对所制备的整体柱的流体力学参数、色谱性能参数进行评价;采用流速梯度洗脱的方式实现9种常见阳离子(Li+,Na+,NH4+,K+,Cs+,Mg2+,Ca2+,Sr2+,Ba2+)的分离分析;此色谱系统还可应用于牛奶中阳离子和三聚氰胺的分离检测.

  9. Prepared polymethacrylate-based monoliths for the separation of cations by non-suppressed capillary ion chromatography.

    Science.gov (United States)

    Li, Jing; Zhu, Yan

    2014-01-01

    This paper describes a novel analytical system for non-suppressed capillary ion chromatography. Methacrylate monolithic columns were prepared from silanized fused-silica capillaries of 320 µm i.d. by in situ polymerization of glycidyl methacrylate and ethylene dimethacrylate in the presence of 1,4-butanediol, 1-propanol and water as the porogen solvents. The introduction of cation-exchange sites was achieved by sulfonating the matrix with sodium sulfite to produce total cation-exchange capacities in the range of 45-105 μequiv/mL for a 25 cm column. The conditions (concentrations of sodium sulfite solution, reacting time and modified flow rate) of sulfonation were optimized. The hydrodynamic and chromatographic performances were estimated. Coupled with a conductivity detector, a capillary ion chromatography system was set up with the prepared column. Finally, the resultant column was used for the separations of five common univalent cations (Li(+), Na(+), NH4(+), K(+) and Cs(+)) using methanesulfonic acid as the eluent and four divalent cations (Mg(2+), Ca(2+), Sr(2+) and Ba(2+)) by non-suppressed capillary ion chromatography; the chromatographic parameters were further researched.

  10. Cation locations and dislocations in zeolites

    Science.gov (United States)

    Smith, Luis James

    The focus of this dissertation is the extra-framework cation sites in a particular structural family of zeolites, chabazite. Cation sites play a particularly important role in the application of these sieves for ion exchange, gas separation, catalysis, and, when the cation is a proton, acid catalysis. Structural characterization is commonly performed through the use of powder diffraction and Rietveld analysis of powder diffraction data. Use of high-resolution nuclear magnetic resonance, in the study of the local order of the various constituent nuclei of zeolites, complements well the long-range order information produced by diffraction. Recent developments in solid state NMR techniques allow for increased study of disorder in zeolites particularly when such phenomena test the detection limits of diffraction. These two powerful characterization techniques, powder diffraction and NMR, offer many insights into the complex interaction of cations with the zeolite framework. The acids site locations in SSZ-13, a high silica chabazite, and SAPO-34, a silicoaluminophosphate with the chabazite structure, were determined. The structure of SAPO-34 upon selective hydration was also determined. The insensitivity of X-rays to hydrogen was avoided through deuteration of the acid zeolites and neutron powder diffraction methods. Protons at inequivalent positions were found to have different acid strengths in both SSZ-13 and SAPO-34. Other light elements are incorporated into zeolites in the form of extra-framework cations, among these are lithium, sodium, and calcium. Not amenable by X-ray powder diffraction methods, the positions of such light cations in fully ion-exchanged versions of synthetic chabazite were determined through neutron powder diffraction methods. The study of more complex binary cation systems were conducted. Powder diffraction and solid state NMR methods (MAS, MQMAS) were used to examine cation site preferences and dislocations in these mixed-akali chabazites

  11. 阳离子型聚丙烯酰胺技术条件及絮凝性能评价研究%Research on the technical conditions and the flocculation capacity evaluation of cationic polyacrylamide

    Institute of Scientific and Technical Information of China (English)

    邵宏谦; 朱传俊; 刘艳飞; 李琳; 白莹

    2014-01-01

    It is require d in the“State Twelfth Five-Year Plan of Energy-Saving and Emissions-Reduction”that for the strengthening of urban sewage treatment facilities construction ,the urban sewage treatment rate and harmless disposal rate in China,should reach 85% and 70%,respectively by 2015. Cationic polyacrylamides,as a kind of sewage treatment and sludge dewatering agent ,has widely been applied to sewage treatment and sludge dewatering. Cationic polyacrylamide has excellent selectivity and adaptability. At present , there have been five series over 2 000 varieties in the world. The world total demand for this product is 650 000 tons annually ,and its annual growth rate is 10%. In the future,the demand for cationic polyacrylamide in the fields,such as sludge dewartering treatment, sewage treatment,petroleum extraction,paper-making,etc. will increase continuously. A series of quality evaluation methods have been made for cationic polyacrylamide and its application to water treatment has been researched.%国家《节能减排“十二五”规划》中,在加强城镇生活污水处理设施建设方面,要求到2015年我国城市污水处理率和污泥无害化处置率分别达到85%和70%。阳离子型聚丙烯酰胺作为一种性能良好的污水处理与污泥脱水剂,被广泛应用于污水处理、污泥脱水处理中。阳离子型聚丙烯酰胺具有优良的选择性和适应性,目前世界有五大系列2000多个品种,世界年总需求量为65万t,年需求增长率为10%。今后我国污泥脱水处理、污水处理、石油开采、造纸等领域对阳离子聚丙烯酰胺的需求量将不断增长。针对阳离子型聚丙烯酰胺制定了系列质量评价方法并对其在水处理应用方面进行了研究。

  12. Study on influence factors of the flux for strong cation-exchange monolithic electroosmotic pump%强阳离子交换整体电渗泵流量影响因素研究

    Institute of Scientific and Technical Information of China (English)

    崔瑞红; 尤慧艳

    2011-01-01

    采用丙烯酸,2-丙烯酰胺-2-甲基丙磺酸为功能单体,N,N’-亚甲基双丙烯酰胺为交联剂,正十二醇、1,4-丁二醇及二甲基亚砜为致孔剂,偶氮二异丁腈为引发剂在原位聚合,制备出了以丙烯酰胺类强阳离子交换整体柱为核心的电渗泵.在乙腈-磷酸盐二元流动相体系下,考察了驱动电压,有机调节剂,盐浓度,pH对该泵流量的影响.流量与驱动电压呈线性关系(0.9991);当有机调节剂乙腈的浓度低于70%时,固定相溶胀为主要因素,流量随乙腈浓度的增加而有下降的趋势,但随着有机调节剂浓度的增加(>70%),此时粘度起主要作用,流量开始缓慢地增加;随着磷酸盐浓度逐渐增加,流量随之降低;在pH 3~9范围内,流量基本上保持恒定.%A strong cation-exchange monolithic electroosmotic column was prepared inside the fused-silica capillary bypolymerization. The solution was consisted of acrylanide, 2-acrylamido-2-methyl-l -propanesulfonicacid as a functional monomer, N, N' -methylenebisacrylanide as a cross-linking agent, dimethyl sulphoxide and dodecanol, 1, 4-Butanediol as organic porogenic reagents and azobisisobutyronitrile as an initiator. The monolithic column was severed as a key part of electroosmotic pump. Effects of applied voltage, the concentrations of organic modifier and salt solution, pH value on the flux were investigated. A good linear relationship between the applied voltage and the flux was obtained (0. 9991 ). The concentration of the organic modifier (CAN)was less than 70%. The swelling degree of stationary phase played a main role, and the flux decreased with increase of the concentration of CAN. However, its concentration was more than 70% , at this time the viscosity of mobile phase was the main influence factor, the flux began to increase slightly. The flux decreased as the concentration of phosphate increased. pH value was in the range of 3 ~ 9, it did not exert a significant change in

  13. 聚苯乙烯磺酸钠阳离子交换树脂(高温磺化)制备浅色高纯树脂的方法%Method for the Preparation of Lighted Colored Sodium Polystyrene Sulfonate Cation-ion-exchange Resin of High Purity Sulfonated at High Temperature

    Institute of Scientific and Technical Information of China (English)

    杨光; 顾浩

    2009-01-01

    Sodium polystyrene sulfonate ion-exchange resin(SPSR) is a medicine used as lowering kalieraia. Using commercial dark colored sodium polystyrene sulfonate cation-ion-exchange resin prepared by the conventional process at the sulfonated temperature higher than 100℃as raw material, light colored SPSR of high purity was prepared by the bleaching-purifying combined process. The resin reached the criterion of medicinal SPSR of Japanese pharmacopoeia(14 ed. ).%聚苯乙烯磺酸钠阳离子交换树脂(SPSR)是降血钾药.以市售的高于100℃的高温磺化工艺生产的深棕色SPSR为原料,经过漂白和净化联合工艺处理,得到了浅色高纯SPSR,该浅色树脂达到日本药典(第14版)规定的药用SPSR标准.

  14. 氢腐蚀分层对换热器筒体承载能力的影响%Influence of bearing capacity of heat exchanger shell caused by hydrogen corrosion delaminating crack

    Institute of Scientific and Technical Information of China (English)

    何家胜; 李超; 朱晓明; 陈伟; 路远明; 杨峰

    2013-01-01

    To explore the influence of hydrogen corrosion delaminating crack on the mechanical properties and bearing capacity in operation of the layered heat exchanger shell, the material capability of layered heat exchanger shell was analyzed by using chemical constituents analysis, hardness test, tensile tests, Charpy V-notch pendulum impact test. The finite element method was used to calculate the stress distribution of heat exchanger shell and to discuss the stress intensity factors of crack tip. The results show that the Mn element is lower in the chemical constituents, other elements accord with the National Standards; the material hardness meets the requirements, but the toughness declines obviously. The material of heat layered exchanger shell is deteriorated by the hydrogen corrosion, which destroys the continuity and uniformity of the material, decreases the ultimate strength, but increases the yield-strength ratio. The film stress state is destroyed, and material resistance to crack growth decreases. The hydrogen corrosion delaminating crack causes biggish partial stress and makes bearing capacity of the heat exchanger shell decrease.%为了解换热器筒体发生氢腐蚀分层后,其简体局部材料的性能发生的变化及对换热器运行中的承载能力带来的影响,采用化学成分分析、硬度测试、拉伸试验、夏比V口冲击韧性试验等方法对换热器筒体材料的性能进行了分析;运用有限元分析方法计算了简体分层处的应力分布,并探讨了裂纹尖端应力强度因子的变化情况.研究结果表明:材料化学成分中除Mn元素的含量偏低外,其它元素含量符合国家标准;材料的硬度符合要求,材料的强度极限降低,屈强比上升,韧性明显降低.氢腐蚀分层使换热器筒体材料局部劣化,破坏了材料的均匀性和连续性,破坏了简体的薄膜应力状态,产生了较大的局部应力,使换热器筒体承载能力下降.

  15. ION EXCHANGE SUBSTANCES BY SAPONIFICATION OF ALLYL PHOSPHATE POLYMERS

    Science.gov (United States)

    Kennedy, J.

    1959-04-14

    An ion exchange resin having a relatively high adsorption capacity tor uranyl ion as compared with many common cations is reported. The resin comprises an alphyl-allyl hydrogen phosphate polymer, the alphyl group being either allyl or a lower alkyl group having up to 5 carbon atoins. The resin is prepared by polymerizing compounds such as alkyl-diallyl phosphate and triallyl phosphate in the presence of a free radical generating substance and then partially hydrolyzing the resulting polymer to cause partial replacement of organic radicals by cations. A preferred free radical gencrating agent is dibenzoyl peroxide. The partial hydrolysis is brought about by refluxing the polymer with concentrated aqueous NaOH for three or four hours.

  16. Long-term tobacco plantation induces soil acidification and soil base cation loss.

    Science.gov (United States)

    Zhang, Yuting; He, Xinhua; Liang, Hong; Zhao, Jian; Zhang, Yueqiang; Xu, Chen; Shi, Xiaojun

    2016-03-01

    Changes in soil exchangeable cations relative to soil acidification are less studied particularly under long-term cash crop plantation. This study investigated soil acidification in an Ali-Periudic Argosols after 10-year (2002-2012) long-term continuous tobacco plantation. Soils were respectively sampled at 1933 and 2143 sites in 2002 and 2012 (also 647 tobacco plants), from seven tobacco plantation counties in the Chongqing Municipal City, southwest China. After 10-year continuous tobacco plantation, a substantial acidification was evidenced by an average decrease of 0.20 soil pH unit with a substantial increase of soil sites toward the acidic status, especially those pH ranging from 4.5 to 5.5, whereas 1.93 kmol H(+) production ha(-1) year(-1) was mostly derived from nitrogen (N) fertilizer input and plant N uptake output. After 1 decade, an average decrease of 27.6 % total exchangeable base cations or of 0.20 pH unit occurred in all seven tobacco plantation counties. Meanwhile, for one unit pH decrease, 40.3 and 28.3 mmol base cations kg(-1) soil were consumed in 2002 and 2012, respectively. Furthermore, the aboveground tobacco biomass harvest removed 339.23 kg base cations ha(-1) year(-1) from soil, which was 7.57 times higher than the anions removal, leading to a 12.52 kmol H(+) production ha(-1) year(-1) as the main reason inducing soil acidification. Overall, our results showed that long-term tobacco plantation not only stimulated soil acidification but also decreased soil acid-buffering capacity, resulting in negative effects on sustainable soil uses. On the other hand, our results addressed the importance of a continuous monitoring of soil pH changes in tobacco plantation sites, which would enhance our understanding of soil fertility of health in this region.

  17. Synthesis and chemical modification of polymeric resins for the treatment of cations and aromatic hydrocarbons in produced oily water; Sintese de modificacao quimica de resina polimerica e aplicacao na remocao de cations e hidrocarbonetos aromaticos presentes em agua produzida

    Energy Technology Data Exchange (ETDEWEB)

    Aversa, Thiago M.; Rodrigues, Monique F.; Vieira, Helida V.P.; Queiros, Yure G.C.; Lucas, Elizabete F. [Universidade Federal do Rio de Janeiro, Instituto de Macromoleculas, Lab. de Macromoleculas e Coloides na Industria do Petroleo, Rio de Janeiro, RJ (Brazil)], e-mail: thiagoaversa@ima.ufrj.br

    2011-07-01

    The use of chemically modified resins in oily water treatment process is not very developed yet. Because of this, this work suggests to study the styrene and divinylbenzene sulfonation effect on oil and grease, aniline and calcium removal from the water. The aniline, oils and greases belong to a class of toxic organic compounds, with the Brazilian maximum limits established for disposal in CONAMA 393/2007, while the calcium ions belong to the group of cations of alkaline earth metals which improve hardness to the water, may cause fouling as carbonates and sulfates form. By using sulfonated resins in oily water treatment it is possible to remove not only oils and greases but also calcium and aniline. These kinds of polar compounds are removed because of the cation exchange capacity of resin. (author)

  18. Neomycin-loaded poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion exchange nanofibers for wound dressing materials.

    Science.gov (United States)

    Nitanan, Todsapon; Akkaramongkolporn, Prasert; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2013-05-01

    In this study, poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) blended with polyvinyl alcohol (PVA) was electrospun and then subjected to thermal crosslinking to produce PSSA-MA/PVA ion exchange nanofiber mats. The cationic drug neomycin (0.001, 0.01, and 0.1%, w/v) was loaded onto the cationic exchange fibers. The amount of neomycin loaded and released and the cytotoxicity of the fiber mats were analyzed. In vivo wound healing tests were also performed in Wistar rats. The results indicated that the diameters of the fibers were on the nanoscale (250 ± 21 nm). The ion exchange capacity (IEC) value and the percentage of water uptake were 2.19 ± 0.1 mequiv./g-dry fibers and 268 ± 15%, respectively. The loading capacity was increased upon increasing the neomycin concentration. An initial concentration of 0.1% (w/v) neomycin (F3) showed the highest loading capacity (65.7 mg/g-dry fibers). The neomycin-loaded nanofiber mats demonstrated satisfactory antibacterial activity against both Gram-positive and Gram-negative bacteria, and an in vivo wound healing test revealed that these mats performed better than gauze and blank nanofiber mats in decreasing acute wound size during the first week after tissue damage. In conclusion, the antibacterial neomycin-loaded PSSA-MA/PVA cationic exchange nanofiber mats have the potential for use as wound dressing materials.

  19. Trace adsorption of positively charged proteins onto Sepharose FF and Sepharose FF-based anion exchangers.

    Science.gov (United States)

    Yu, Lin-Ling; Sun, Yan

    2012-08-31

    Agarose-based matrices have been widely used in ion exchange chromatography (IEC). We have herein observed that positively charged proteins (lysozyme and cytochrome c) are adsorbed on the agarose-based anion-exchangers (Q and DEAE Sepharose FF gels) in a capacity of 10-40 μg/mL. In contrast, negatively charged protein (bovine serum albumin) is not adsorbed to Sepharose FF and SP Sepharose FF gels. Elemental analysis of the gel indicated that the residual anionic sulfate groups in agarose would have worked as the cation exchange groups for the positively charged proteins. The trace adsorption behavior of lysozyme onto Sepharose FF and Sepharose FF-based anion exchangers was studied and the effects of NaCl concentration and cation group density on the adsorption were examined for better understanding of the trace adsorption in chromatographic processes. At NaCl concentrations less than 0.05 mol/L, which is the normal adsorption condition in IEC, the trace adsorption kept at a high level, so this trace adsorption cannot be avoided in the ionic strength range of routine IEC operations. Grafting poly(ethylenimine) (PEI) chain of 60 kDa to a cation group density of 700 mmol/L could reduce the adsorption capacity to about 20 μg/mL, but further reduction was not possible by increasing the cation group density to 1200 mmol/L. Therefore, attentions need to be paid to the phenomenon in protein purification practice using agarose-based matrices. The research is expected to call attentions to the trace adsorption on agarose-based matrices and to the importance in the selection of the suitable solid matrices in the production of high-purity protein products in large-scale bioprocesses.

  20. Simultaneous determination of NH4+, NO2(-) and NO3(-) by ion-exclusion/anion-exchange chromatography on a strongly basic anion-exchange resin with basic eluent.

    Science.gov (United States)

    Mori, Masanobu; Hironaga, Takahiro; Itabashi, Hideyuki; Nakatani, Nobutake; Kozaki, Daisuke; Tanaka, Kazuhiko

    2012-04-01

    Ion-exclusion/anion-exchange chromatography (IEC/AEC) on a combination of a strongly basic anion-exchange resin in the OH(-)-form with basic eluent has been developed. The separation mechanism is based on the ion-exclusion/penetration effect for cations and the anion-exchange effect for anions to anion-exchange resin phase. This system is useful for simultaneous separation and determination of ammonium ion (NH4+), nitrite ion (NO2(-)), and nitrate ion (NO3(-)) in water samples. The resolution of analyte ions can be manipulated by changing the concentration of base in eluent on a polystyrene-divinylbenzene based strongly basic anion-exchange resin column. In this study, several separation columns, which consisted of different particle sizes, different functional groups and different anion-exchange capacities, were compared. As the results, the separation column with the smaller anion-exchange capacity (TSKgel Super IC-Anion) showed well-resolved separation of cations and anions. In the optimization of the basic eluent, lithium hydroxide (LiOH) was used as the eluent and the optimal concentration was concluded to be 2 mmol/L, considering the resolution of analyte ions and the whole retention times. In the optimal conditions, the relative standard deviations of the peak areas and the retention times of NH4+, NO2(-), and NO3(-) ranged 1.28% - 3.57% and 0.54% - 1.55%, respectively. The limits of detection at signal-to-noise of 3 were 4.10 micromol/L for NH4+, 1.87 micromol/L for NO2(-) and 2.83 micromol/L for NO3(-).

  1. Effect of interlayer cations of montmorillonite on the biodegradation and adsorption of crude oil polycyclic aromatic compounds.

    Science.gov (United States)

    Ugochukwu, Uzochukwu C; Manning, David A C; Fialips, Claire I

    2014-09-01

    Cation exchange capacity, surface acidity and specific surface area are surface properties of clay minerals that make them act as catalysts or supports in most biogeochemical processes hence making them play important roles in environmental control. However, the role of homoionic clay minerals during the biodegradation of polycyclic aromatic compounds is not well reported. In this study, the effect of interlayer cations of montmorillonites in the removal of some crude oil polycyclic aromatic compounds during biodegradation was investigated in aqueous clay/oil microcosm experiments with a hydrocarbon degrading microorganism community. The homoionic montmorillonites were prepared via cation exchange reactions by treating the unmodified montmorillonite with the relevant metallic chloride. The study indicated that potassium-montmorillonite and zinc-montmorillonite did not enhance the biodegradation of the polycyclic aromatic hydrocarbons whereas calcium-montmorillonite, and ferric-montmorillonite enhanced their biodegradation significantly. Adsorption of polycyclic aromatic hydrocarbons was significant during biodegradation with potassium- and zinc-montmorillonite where there was about 45% removal of the polycyclic aromatic compounds by adsorption in the experimental microcosm containing 5:1 ratio (w/w) of clay to oil.

  2. Textural and hydration properties of a synthetic montmorillonite compared with a natural Na-exchanged clay analogue.

    OpenAIRE

    2010-01-01

    International audience; An aluminous montmorillonite has been synthesized at hydrothermal conditions (623 K, 120 MPa) and compared to the natural Na-exchanged Wyoming montmorillonite (Na-SWy2). The synthetic product is characterized by a high cation exchange capacity (83 meq/100g) and ethylene glycol specific surface area (764 m2/g) similar to Na-SWy2 but with a higher purity with one crystalline phase. Compacted smectite samples were percolated with water by using an œdometer cell equipped w...

  3. The effects of cationic contamination on the physio-chemical properties of perfluoroionomer membranes

    Science.gov (United States)

    Molter, Trent M.

    Proton Exchange Membrane (PEM) technology cannot meet fuel cell and electrolyzer durability standards for stationary and transportation applications. Cell designs are not of sufficient maturity to demonstrate more than several thousand hours of invariant performance. One of the limiting factors is the operational lifetime of membrane electrode assemblies (MEA's) because of pin-holing, dry-out, mechanical breeches, chemical attack and contamination. This program investigated the role of contamination on the degradation of perfluorinated membranes in fuel cell and electrolysis environments. Tests were conducted to develop an understanding of the effects of cationic contaminants on fundamental design parameters for these membranes including water content, ion exchange capacity, gas diffusion, ionic conductivity, and mechanical properties. Tests showed that cations rapidly transport into the membrane and disperse throughout its structure achieving high equilibrium concentrations. Ion charge density appears to govern membrane water content with small ions demonstrating the highest water content. Permeability studies showed transport in accordance with Fick's law in the following order: H2>O2>N 2>H2O. Cations negatively affect gas and water transport, with charge density affecting transport rates. Unique diffusion coefficients were calculated for each contaminating species suggesting that the contaminant is an integral participant in the transport process. AC resistance measurements showed that size of the ion charge carrier is an important factor in the conduction mechanism and that membrane area specific resistance correlates well with water content. Increases in membrane yield strength and the modulus of elasticity were demonstrated with increased contamination. Tensile tests showed that cation size plays an important role in determining the magnitude of this increase, indicating that larger ions interfere more with strain than smaller ones. Contaminants reduced

  4. 基于矿物组分模型的阳离子交换容量评价新方法%A New Method of Cation-exchange Capacity Evaluation Based on Mineral Composition Model

    Institute of Scientific and Technical Information of China (English)

    孙建孟; 张丽艳; 张磊

    2010-01-01

    阳离子交换容量(Qv)是Waxman-Smits模型的关键参数,利用常规测井求准Qv是岩石物理分析家一直探讨的热点.在充分利用测井曲线和全岩矿物衍射、黏土矿物衍射岩心分析资料的基础上,提出了基于矿物组分模型求解各种黏土矿物含量的新方法,与衍射岩心分析结果一致;结合各种黏土矿物的岩石阳离子交换能力(CEC)值,可求得地层总的CEC值,继而可以求得Qv曲线,结果与阳离子交换能力实验相吻合;在低电阻率层段利用Waxman-Smits模型计算的含油饱和度比Archie公式更加合理.

  5. Separation behavior of U(VI) and Th(IV) on a cation exchange column using 2,6-pyridine dicarboxylic acid as a complexing agent and its application for the rapid separation and determination of U and Th by ion chromatography.

    Science.gov (United States)

    Jeyakumar, Subbiah; Mishra, Vivekchandra Guruprasad; Das, Mrinal Kanti; Raut, Vaibhavi Vishwajeet; Sawant, Ramesh Mahadev; Ramakumar, Karanam Lakshminarayana

    2011-03-01

    The retention behavior of U and Th as their 2,6-pyridine dicarboxylic acid (PDCA) complexes on a cation exchange column was investigated under low pH conditions. Based on the observed retention characteristics, an ion chromatographic method for the rapid separation of uranium and thorium in isocratic elution mode using 0.08 mM PDCA and 0.24 M KNO(3) in 0.22 M HNO(3) as the eluent was developed. Both uranium and thorium were eluted as their PDCA complexes within 2 min, whereas the transition and lanthanide metal cations were eluted as an unresolved broad peak after thorium. Under the optimized conditions both U and Th have no interference either from alkali and alkaline earth elements up to a concentration ratio of 1:500 or from other elements up to 1:100. The detection limits (LOD) of U and Th were calculated as 0.04 and 0.06 ppm, respectively (S/N=3). The precision in the measurement of peak area of 0.5 ppm of both U and Th was better than 5% and a linear calibration in the concentration range of 0.25-25 ppm of U and Th was obtained. The method was successfully applied to determine U and Th in effluent water samples.

  6. Drivers of Tree Species Effects on Phosphorus and Cation Cycling in Plantations at La Selva Biological Station, Costa Rica

    Science.gov (United States)

    Russell, A. E.

    2014-12-01

    Fast-growing trees in secondary forests and plantations in the humid tropics play an important role in the atmospheric CO2 balance owing to their high rates of carbon sequestration. Because plants require nutrients to sustain high CO2 uptake, differences among tree species in traits related to nutrient uptake, retention and recycling could influence ecosystem-scale carbon cycling. A better understanding of the relationships among plant traits, nutrient and carbon cycling will thus improve ecosystem- to global scale modeling of effects of vegetation change on carbon cycling. In an experimental setting in which state factors were similar among four species of tropical trees situated on an Oxisol in replicated, 25-yr-old, mono-dominant plantations, I evaluated various drivers of aboveground storage of phosphorus (P) and cations, measuring nutrient fluxes in litterfall and fine-root growth and storage in biomass and soil to 1-m depth. Because fine roots increase the capacity to scavenge nutrients already on exchange sites within the soil environment, I hypothesized that P and cation uptake would be correlated directly with fine-root growth. The four tree species in this experiment, Hieronyma alchorneoides, Pentaclethra macroloba, Virola koschnyi, and Vochysia guatemalensis differed significantly in net cation uptake over the first 25 years of growth (P = 0.013, Ca; P >0.0001, Mg, Mn, K, Al, Fe, and Sr). For all cations, aboveground tree biomass was highly correlated with fine-root ingrowth length, with P values >0.0001 for all cations except Ca (P = 0.013). In contrast for P, differences among species were only marginally significant (P = 0.062). Similarly, P in aboveground tree biomass was marginally correlated with fine-root ingrowth (P = 0.068). Neither cation nor P uptake was correlated with measures of available P and cations, organic or total P in surface soil. For P, the less significant correlation with fine-root growth suggests that some other mechanism, such

  7. Capacity and mechanisms of ammonium and cadmium sorption on different wetland-plant derived biochars

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Xiaoqiang [Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Hao, Hulin [Ningbo Raw Water Resource Research Academy, Ningbo (China); Zhang, Changkuan [Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); He, Zhenli [Indian River Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Fort Pierce, FL 34945 (United States); Yang, Xiaoe, E-mail: xyang571@yahoo.com [Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China)

    2016-01-01

    The objective of this study was to investigate the relationship between Cd{sup 2+}/NH{sub 4}{sup +} sorption and physicochemical properties of biochars produced from different wetland plants. Biochars from six species of wetland plants (i.e., Canna indica, Pennisetum purpureum Schum, Thalia dealbata, Zizania caduciflora, Phragmites australis and Vetiveria zizanioides) were obtained at 500 °C and characterized, and their sorption for ammonium and cadmium was determined. There were significant differences in elemental composition, functional groups and specific surface area among the biochars derived from different wetland plant species. Sorption of ammonium and cadmium on the biochars could be described by a pseudo second order kinetic model, and the simple Langmuir model fits the isotherm data better than the Freundlich or Temkin model. The C. indica derived biochar had the largest sorption capacity for NH{sub 4}{sup +} and Cd{sup 2+}, with a maximum sorption of 13.35 and 125.8 mg g{sup −1}, respectively. P. purpureum Schum derived biochar had a similar maximum sorption (119.3 mg g{sup −1}) for Cd{sup 2+}. Ammonium sorption was mainly controlled by cation exchange, surface complexation with oxygen-containing functional groups and the formation of magnesium ammonium phosphate compounds, whereas for Cd{sup 2+} sorption, the formation of cadmium phosphate precipitates, cation exchange and binding to oxygen-containing groups were the major possible mechanisms. In addition, the sorption of ammonium and cadmium was not affected by surface area and microporosity of the biochars. - Highlights: • Biochars varied in physicochemical properties and adsorption capacity. • Canna indica derived biochar has a high sorption capacity for Cd{sup 2+}. • NH{sub 4}{sup +} and Cd{sup 2+} sorption on biochars fits a pseudo second order and Langmuir model. • Sorption mechanism is related to complexation, cation exchange and precipitation.

  8. The magnetic Curie temperature and exchange coupling between cations in tetragonal spinel oxide Mn{sub 2.5}M{sub 0.5}O{sub 4} (M = Co, Ni, Mn, Cr, and Mg) films

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, K.; Cheng, C. W.; Chern, G. [Physics Department and SPIN Research Center, National Chung Cheng University, Chia-Yi, Taiwan, 621 (China)

    2012-04-01

    Mn{sub 3}O{sub 4} is a Jahn-Taller tetragonal ferrite that has a relatively low Curie temperature (T{sub c}) of {approx}43 K due to weak coupling between the canting spins. In this study, we fabricated a series of 100-nm-thick Mn{sub 2.5}M{sub 0.5}O{sub 4} (M = Co, Ni, Mn, Cr, and Mg) films via oxygen-plasma-assisted molecular beam epitaxy and measured the structural and magnetic properties of these films. These films show single phase quality, and the c-axis lattice parameter of pure Mn{sub 3}O{sub 4} is 0.944 nm, with a c/a ratio {approx}1.16, consistent with the bulk values. The replacement of Mn by M (M = Co, Ni, Cr, and Mg) changes the lattice parameters, and the c/a ratio varies between 1.16 and 1.06 depending upon the cation distribution of the films. The magnetic Curie temperatures of these films also vary in the range of 25-66 K in that Ni and Co enhance the T{sub c} whereas Mg reduces the T{sub c} (Cr shows no effect on the T{sub c}). These changes to the T{sub c} are related to both the element electronic state and the cation distributions in these compounds. As a non-collinear spin configuration can induce electrical polarization, the present study provides a systematic way to enhance the magnetic transition temperature in tetragonal spinel ferrites.

  9. Influence of the ionic liquid cation on the solvent extraction of trivalent rare-earth ions by mixtures of Cyanex 923 and ionic liquids.

    Science.gov (United States)

    Rout, Alok; Binnemans, Koen

    2015-01-21

    Trivalent rare-earth ions were extracted from nitric acid medium by the neutral phosphine oxide extractant Cyanex 923 into ionic liquid phases containing the bis(trifluoromethylsulfonyl)imide anion. Five different cations were considered: 1-butyl-3-methylimidazolium, 1-decyl-3-methylimidazolium, methyltributylammonium, methyltrioctylammonium and trihexyl(tetradecyl)phosphonium. The extraction behavior of neodymium(iii) was investigated as a function of various parameters: pH, extractant concentration, concentration of the neodymium(iii) ion in the aqueous feed and concentration of the salting-out agent. The loading capacity of the ionic liquid phase was studied. The extraction efficiency increased with increasing pH of the aqueous feed solution. The extraction occurred for all ionic liquids via an ion-exchange mechanism and the extraction efficiency could be related to the solubility of the ionic liquid cation in the aqueous phase: high distribution ratios for hydrophilic cations and low ones for hydrophobic cations. Addition of nitrate ions to the aqueous phase resulted in an increase in extraction efficiency for ionic liquids with hydrophobic cations due to extraction of neutral complexes. Neodymium(iii) could be stripped from the ionic liquid phase by 0.5-1.0 M nitric acid solutions and the extracting phase could be reused. The extractability of other rare earths present in the mixture was compared for the five ionic liquids.

  10. Thermodynamic Modeling of Sulfide Capacity of Na2O-Containing Oxide Melts

    Science.gov (United States)

    Moosavi-Khoonsari, Elmira; Jung, In-Ho

    2016-10-01

    Thermodynamic modeling of the sulfide dissolution in the Na2O-FetO-CaO-MgO-MnO-Al2O3-SiO2 multicomponent slags was performed to investigate the desulfurization of hot metal using Na2O-containing fluxes. The dissolution behavior of sulfur in the melts was modeled using the modified quasi-chemical model in the quadruplet approximation. This model can take into account the short-range ordering and the reciprocal exchange reaction of cations and anions in oxy-sulfide slags. Experimental sulfide capacity data were well predicted from the model with only three model parameters.

  11. Evaluation of capacity ion exchange of MMT-Na{sup +w}ith rare earth salts for use in polymeric nano composites; Avaliacao da capacidade de troca ionica da MMT-Na{sup +c}om sais de terras raras para aplicacao em nanocompositos polimericos

    Energy Technology Data Exchange (ETDEWEB)

    Maino, Isabel B.; Scienza, Lisete C. [Universidade de Caxias do Sul (UCS). CCET. Laboratorio de Protecao Superficial e Corrosao, Caxias do Sul, RS (Brazil); Piazza, Diego; Zattera, Ademir J. [Universidade de Caxias do Sul (UCS). CCET. Laboratorio de Polimeros (Brazil); Ferreira, Carlos A., E-mail: dpiazza1@ucs.br [Universidade Federal do Rio Grande do Sul (UFRGS). Laboratorio de Polimeros (Brazil)

    2011-07-01

    The modification of the montmorillonite clay is associated with materials science, arousing interest in science and technology provide significant improvements when incorporated into polymeric materials neat and conventional composites. The process of modification of clays occurs mainly through the ion exchange of exchangeable cations in its crystal structure. In this study, we performed ion exchange of sodium montmorillonite with rare earth salts (cerium) through two routes: centrifugation and filtration. The samples were characterized by X-ray diffraction (XRD) and energy dispersive analysis by X-ray (EDS). The sample obtained by the filtration route showed an increase of basal clay by XRD, indicating the presence of salts of cerium on the structure, and corroborated by EDS analysis. (author)

  12. Simultaneous determination of NH4+, NO2- and NO3- by ion-exclusion/anion-exchange chromatography on a strongly basic anion-exchange resin with basic eluent%Simultaneous determination of NH4+,NO2- and NO3- by ion-exclusion/anion-exchange chromatography on a strongly basic anion-exchange resin with basic eluent

    Institute of Scientific and Technical Information of China (English)

    Masanobu MORI; Takahiro HIRONAGA; Hideyuki ITABASHI; Nobutake NAKATANI; Daisuke KOZAKI; Kazuhiko TANAKA

    2012-01-01

    Ion-exclusion/anion-exchange chromatography (IEC/AEC) on a combination of a strongly basic anion-exchange resin in the OH--form with basic eluent has been developed.The separation mechanism is based on the ion-exclusion/penetration effect for cations and the anion-exchange effect for anions to anion-exchange resin phase.This system is useful for simultaneous separation and determination of ammonium ion ( NH4+ ),nitrite ion (NO2-),and nitrate ion (NO3-) in water samples.The resolution of analyte ions can be manipulated by changing the concentration of base in eluent on a polystyrene-divinylbenzene based strongly basic anion-exchange resin column.In this study,several separation columns,which consisted of different particle sizes,different functional groups and different anion-exchange capacities,were compared.As the results,the separation column with the smaller anion-exchange capacity (TSKgel Super IC-Anion) showed well-resolved separation of cations and anions,In the optimization of the basic eluent,lithium hydroxide (LiOH) was used as the eluent and the optimal concentration was concluded to be 2 mmol/L,considering the resolution of analyte ions and the whole retention times.In the optimal conditions,the relative standard deviations of the peak areas and the retention times of NH4+,NO2-,and NO3- ranged 1.28% - 3.57% and 0.54% - 1.55%,respectively.The limits of detection at signal-to-noise of 3 were 4.10 μmol/L for NH4+,1.87 μmol/L for NO2- and 2.83 μmol/L for NO3-.

  13. Zebrafish ("Danio rerio") endomembrane antiporter similar to a yeast cation/H(+) transporter is required for neural crest development

    Science.gov (United States)

    CAtion/H (+) eXchangers (CAXs) are integral membrane proteins that transport Ca (2+) or other cations by exchange with protons. While several yeast and plant CAX proteins have been characterized, no functional analysis of a vertebrate CAX homologue has yet been reported. In this study, we further ch...

  14. Role of extracellular cations in cell motility, polarity, and chemotaxis

    Directory of Open Access Journals (Sweden)

    Soll D

    2011-04-01

    Full Text Available David R Soll1, Deborah Wessels1, Daniel F Lusche1, Spencer Kuhl1, Amanda Scherer1, Shawna Grimm1,21Monoclonal Antibody Research Institute, Developmental Studies, Hybridoma Bank, Department of Biology, University of Iowa, Iowa City; 2Mercy Medical Center, Surgical Residency Program, Des Moines, Iowa, USAAbstract: The concentration of cations in the aqueous environment of free living organisms and cells within the human body influence motility, shape, and chemotaxis. The role of extracellular cations is usually perceived to be the source for intracellular cations in the process of homeostasis. The role of surface molecules that interact with extracellular cations is believed to be that of channels, transporters, and exchangers. However, the role of Ca2+ as a signal and chemoattractant and the discovery of the Ca2+ receptor have demonstrated that extracellular cations can function as signals at the cell surface, and the plasma membrane molecules they interact with can function as bona fide receptors that activate coupled signal transduction pathways, associated molecules in the plasma membrane, or the cytoskeleton. With this perspective in mind, we have reviewed the cationic composition of aqueous environments of free living cells and cells that move in multicellular organisms, most notably humans, the range of molecules interacting with cations at the cell surface, the concept of a cell surface cation receptor, and the roles extracellular cations and plasma membrane proteins that interact with them play in the regulation of motility, shape, and chemotaxis. Hopefully, the perspective of this review will increase awareness of the roles extracellular cations play and the possibility that many of the plasma membrane proteins that interact with them could also play roles as receptors.Keywords: extracellular cations, chemotaxis, transporters, calcium, receptors

  15. Plasma-grafted alkaline anion-exchange membranes based on polyvinyl chloride for potential application in direct alcohol fuel cell

    Science.gov (United States)

    Hu, Jue; Zhang, Chengxu; Cong, Jie; Toyoda, Hirotaka; Nagatsu, Masaaki; Meng, Yuedong

    2011-05-01

    Plasma grafting is employed to prepare alkaline anion-exchange membranes in this study. The attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermo gravimetric analysis demonstrate that the benzyltrimethylammonium cationic groups are successfully introduced into the polyvinyl chloride matrix via plasma grafting, quaternization and alkalization. The plasma-grafted alkaline anion-exchange membrane exhibits a satisfactory ionic exchange capacity (1.01 mmol g-1), thermal stability, mechanical property, ionic conductivity (0.0145 S cm-1) and methanol permeability (9.59 × 10-12 m2 s-1), suggesting a great potential for application in direct alcohol fuel cells. The open circuit voltage of air-breathing ADAFC using plasma-grafted alkaline anion-exchange membrane is 0.796 V with 1 M EtOH solution at ambient temperature.

  16. Sorption of the organic cation metoprolol on silica gel from its aqueous solution considering the competition of inorganic cations.

    Science.gov (United States)

    Kutzner, Susann; Schaffer, Mario; Börnick, Hilmar; Licha, Tobias; Worch, Eckhard

    2014-05-01

    Systematic batch experiments with the organic monovalent cation metoprolol as sorbate and the synthetic material silica gel as sorbent were conducted with the aim of characterizing the sorption of organic cations onto charged surfaces. Sorption isotherms for metoprolol (>99% protonated in the tested pH of around 6) in competition with mono- and divalent inorganic cations (Na(+), NH4(+), Ca(2+), and Mg(2+)) were determined in order to assess their influence on cation exchange processes and to identify the role of further sorptive interactions. The obtained sorption isotherms could be described well by an exponential function (Freundlich isotherm model) with consistent exponents (about 0.8). In general, a decreasing sorption of metoprolol with increasing concentrations in inorganic cations was observed. Competing ions of the same valence showed similar effects. A significant sorption affinity of metoprolol with ion type dependent Freundlich coefficients KF,0.77 between 234.42 and 426.58 (L/kg)(0.77) could still be observed even at very high concentrations of competing inorganic cations. Additional column experiments confirm this behavior, which suggests the existence of further relevant interactions beside cation exchange. In subsequent batch experiments, the influence of mixtures with more than one competing ion and the effect of a reduced negative surface charge at a pH below the point of zero charge (pHPZC ≈ 2.5) were also investigated. Finally, the study demonstrates that cation exchange is the most relevant but not the sole mechanism for the sorption of metoprolol on silica gel.

  17. Peak capacity in unidimensional chromatography.

    Science.gov (United States)

    Neue, Uwe Dieter

    2008-03-14

    The currently existing knowledge about peak capacity in unidimensional separations is reviewed. The majority of the paper is dedicated to reversed-phase gradient chromatography, covering specific techniques as well as the subject of peak compression. Other sections deal with peak capacity in isocratic chromatography, size-exclusion chromatography and ion-exchange chromatography. An important topic is the limitation of the separation power and the meaning of the concept of peak capacity for real applications.

  18. Recycling asymmetric hydrogenation catalysts by their immobilisation onto ion-exchange resins.

    Science.gov (United States)

    Barbaro, Pierluigi; Bianchini, Claudio; Giambastiani, Giuliano; Oberhauser, Werner; Bonzi, Laura Morassi; Rossi, Filippo; Dal Santo, Vladimiro

    2004-06-21

    New systems based on cationic chiral phosphine-rhodium complexes anchored to a commercial cation-exchange gel-type resin showed high efficiency and easy recycling in the asymmetric hydrogenation of prochiral olefins.

  19. Biological removal of cationic fission products from nuclear wastewater.

    Science.gov (United States)

    Ngwenya, N; Chirwa, E M N

    2011-01-01

    Nuclear energy is becoming a preferred energy source amidst rising concerns over the impacts of fossil fuel based energy on global warming and climate change. However, the radioactive waste generated during nuclear power generation contains harmful long-lived fission products such as strontium (Sr). In this study, cationic strontium uptake from solution by microbial cultures obtained from mine wastewater is evaluated. A high strontium removal capacity (q(max)) with maximum loading of 444 mg/g biomass was achieved by a mixed sulphate reducing bacteria (SRB) culture. Sr removal in SRB was facilitated by cell surface based electrostatic interactions with the formation of weak ionic bonds, as 68% of the adsorbed Sr(2+) was easily desorbed from the biomass in an ion exchange reaction with MgCl₂. To a lesser extent, precipitation reactions were also found to account for the removal of Sr from aqueous solution as about 3% of the sorbed Sr was precipitated due to the presence of chemical ligands while the remainder occurred as an immobile fraction. Further analysis of the Sr-loaded SRB biomass by scanning electron microscopy (SEM) coupled to energy dispersive X-ray (EDX) confirmed extracellular Sr(2+) precipitation as a result of chemical interaction. In summary, the obtained results demonstrate the prospects of using biological technologies for the remediation of industrial wastewaters contaminated by fission products.

  20. Removal of chromium from electroplating industry effluents by ion exchange resins.

    Science.gov (United States)

    Cavaco, Sofia A; Fernandes, Sandra; Quina, Margarida M; Ferreira, Licínio M

    2007-06-18

    Effluent discharged from the chromium electroplating industry contains a large number of metals, including chromium, copper, nickel, zinc, manganese and lead. The ion exchange process is an alternative technique for application in the treatment of industrial wastewater containing heavy metals and indeed it has proven to be very promising in the removal and recovery of valuable species. The main objective of the present work is to evaluate the performance of commercial ion exchange resins for removing chromium trivalent from industrial effluents, and for this purpose two resins were tested: a chelating exchange resin (Diaion CR11) and a weak cationic resin (Amberlite IRC86). In order to evaluate the sorption capacity of the resins some equilibrium experiments were carried out, being the temperature and pH the main variables considered. The chromium solutions employed in the experiments were synthetic solutions and industrial effluents. In addition, a transient test was also performed as an attempt to understand the kinetic behaviour of the process.

  1. CHARACTERIZATION OF REACTIVE FORMATIONS: A VISION FOR THE CAPACITY EXPANSION

    Directory of Open Access Journals (Sweden)

    Danielly Vieira de Lucena

    2013-12-01

    Full Text Available All classes of clay minerals absorb water, but the smectite absorb much larger volumes than the other classes because of its expanded network. During the drilling of oil wells it is common for the detection of layers consisting of clay minerals high grade of hydration arranged in laminar packages. When in contact with water, the packets are separated clay as the water enters the basal spacing. This phenomenon is known as expansion or swelling. Given this, this paper aims to characterize shales in two regions of the country to explain the susceptibility of hydration of each of these formations. The characterization was done by making use of Exchange cation capacity (ECC, X-ray fluorescence (XRF, diferential thermal analysis (DTA, Thermogravimetry (TGA and X-ray diffraction (XRD. The results obtained showed that among the shales studied, those with the greatest degree of clay fractions (smectite in its composition showed higher swelling index according to the methodology of Foster.

  2. Station Capacity

    DEFF Research Database (Denmark)

    Landex, Alex

    2011-01-01

    Stations are often limiting the capacity of railway networks. This is due to extra need of tracks when trains stand still, trains turning around, and conflicting train routes. Although stations are often the capacity bottlenecks, most capacity analysis methods focus on open line capacity. Therefore......, this paper presents methods to analyze station capacity. Four methods to analyze station capacity are developed. The first method is an adapted UIC 406 capacity method that can be used to analyze switch zones and platform tracks at stations that are not too complex. The second method examines the need...... for platform tracks and the probability that arriving trains will not get a platform track immediately at arrival. The third method is a scalable method that analyzes the conflicts in the switch zone(s). In its simplest stage, the method just analyzes the track layout while the more advanced stages also take...

  3. A single pump cycling-column-switching technique coupled with homemade high exchange capacity columns for the determination of iodate in iodized edible salt by ion chromatography with UV detection.

    Science.gov (United States)

    Huang, Zhongping; Subhani, Qamar; Zhu, Zuoyi; Guo, Weiqiang; Zhu, Yan

    2013-08-15

    A single pump cycling-column-switching technique has been developed for the iodate analysis in edible salt. Homemade high exchange capacity columns were adopted for the separation of iodate and chloride. Iodate could be retained and concentrated in a homemade concentrator column after eluents passing through the suppressor. With UV detection, iodate exhibited satisfactory linearity in the range of 0.1-10.0 mg/L with a correlation coefficient of 0.9996. The detection limit (LOD) was 45.53 μg/L, based on the signal-to-noise ratio of 3 (S/N=3) and a 100 μL injection volume. Relative standard deviations (RSDs) for retention time, peak area and peak height were all less than 2.1%. Recoveries of added iodate were in the range of 98.4-101.6% for the spiked samples. The quantitative determination of iodate in edible salt was accomplished by this column-switching technique, without any pretreatment and interference. The results on six samples were statistically compared with results determined by conventional titrimetric method.

  4. Two different cationic positions in Cu-SSZ-13?

    Science.gov (United States)

    Hun Kwak, Ja; Zhu, Haiyang; Lee, Jong H; Peden, Charles H F; Szanyi, János

    2012-05-16

    H(2)-TPR and FTIR were used to characterize the nature of the Cu ions present in the Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ions at two distinct cationic positions in the SSZ-13 framework.

  5. Two different cationic positions in Cu-SSZ-13?

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Zhu, Haiyang; Lee, Jong H.; Peden, Charles HF; Szanyi, Janos

    2012-04-18

    H2-TPR and FTIR were used to characterize the Cu ions present in Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ions in two distinct cationic positions of the SSZ-13 framework.

  6. 基于大肠杆菌蛋白质质谱鉴定的阳离子交换色谱优化研究%Optimization of conditions for the separation with strong cation exchange chromatography based on Escherichia coli protein for mass spectrometry identification

    Institute of Scientific and Technical Information of China (English)

    朱平川; 岑卫健; 付强; 胡炜; 卢洁

    2014-01-01

    As a research of tryptic digestion products from Escherichia coli protein , on the extraction efficiency of protein were studied in this paper ,The focus is on the separation conditions of strong cation used multidimensional chromatography exchange chromatography . The conditions included the buffer species ,pH ,the type of the salt in mobile phase ,the proportion of organic solvent added in the elution solution ,and the loading amount of the sample .The results showed that ,in the power of 400 W ,ultrasonic time was 15 minutes ,achieved the highest extraction efficiency of protein . In the strong cation exchange chromatography separation of linear sample volume range ,10 mmol/L potassium dihydrogen phosphate (pH = 3 .0 ) of mobile phases and 30% (V/V ) organic solvent in mobile phases as buffer system ,as washing desalination in potassium chloride solution ,can obtain the best separation results .%以大肠杆菌蛋白质的胰蛋白酶切产物为研究对象,对蛋白质的提取效率进行初步探讨,重点是对多维色谱分离中常用的强阳离子交换色谱的分离条件,包括缓冲液的种类、pH值,洗脱盐的种类、有机溶剂的比例以及上样量进行了考察和比较.结果表明:功率为400 W ,超声时间为15 min ,蛋白质的提取效率达到最高.在强阳离子交换色谱分离线性上样量范围内,10 mmol/L磷酸二氢钾(pH=3.0)作为缓冲体系,在氯化钾溶液作为洗脱盐、流动相中乙腈的体积分数为30%的条件下进行梯度洗脱时,可获得最佳的分离结果.

  7. Competitive Effects of 2+ and 3+ Cations on DNA Compaction

    CERN Document Server

    Tongu, C; Yoshikawa, Y; Zinchenko, A A; Chen, N; Yoshikawa, K

    2016-01-01

    By using single-DNA observation with fluorescence microscopy, we observed the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA with 166 kbp). It was found that divalent cations, such as Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. These experimental observations are inconsistent with the well-established Debye-Huckel scheme regarding the shielding effect of counter ions, which is given as the additivity of contributions of cations with different valences. We interpreted the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counter ions before and after the folding transition of DNA. For the compaction with SPD(3+), we considered the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly-charged polyelectrolyte, double-st...

  8. Atmospheric CO2 enrichment facilitates cation release from soil.

    Science.gov (United States)

    Cheng, L; Zhu, J; Chen, G; Zheng, X; Oh, N-H; Rufty, T W; Richter, D deB; Hu, S

    2010-03-01

    Atmospheric CO(2) enrichment generally stimulates plant photosynthesis and nutrient uptake, modifying the local and global cycling of bioactive elements. Although nutrient cations affect the long-term productivity and carbon balance of terrestrial ecosystems, little is known about the effect of CO(2) enrichment on cation availability in soil. In this study, we present evidence for a novel mechanism of CO(2)-enhancement of cation release from soil in rice agricultural systems. Elevated CO(2) increased organic C allocation belowground and net H(+) excretion from roots, and stimulated root and microbial respiration, reducing soil redox potential and increasing Fe(2+) and Mn(2+) in soil solutions. Increased H(+), Fe(2+), and Mn(2+) promoted Ca(2+) and Mg(2+) release from soil cation exchange sites. These results indicate that over the short term, elevated CO(2) may stimulate cation release from soil and enhance plant growth. Over the long-term, however, CO(2)-induced cation release may facilitate cation losses and soil acidification, negatively feeding back to the productivity of terrestrial ecosystems.

  9. 阳离子交换法制备稳定的近红外区核/壳型PbS/CdS量子点%Utilizing Cation Exchange Method to Produce Core/Shell PbS/CdS Quantum Dots with Stable Infrared Emission

    Institute of Scientific and Technical Information of China (English)

    李谦; 张腾; 古宏伟; 丁发柱; 屈飞; 彭星煜; 王洪艳; 吴战鹏

    2013-01-01

    硫化铅量子点(PbS QDs)的光氧化稳定性差是其应用于太阳能电池等领域的主要限制因素之一.采用阳离子交换法在合成的PbS量子点表面包裹一层具有更稳定、更大禁带宽度的硫化镉(CdS)壳层,制备出稳定的核/壳型PbS/CdS量子点;同时,研究了反应温度和反应时间对阳离子交换过程的影响规律.通过透射电子显微镜和高分辨透射电子显微镜(TEM/HRTEM)、X射线衍射仪(XRD)、吸收光谱和荧光光谱考察了所制备PbS/CdS量子点的结构、光学特性和光氧化稳定性,结果表明:阳离子交换过程中,离子交换反应程度有限、仅发生在量子点的表面层,但极薄的CdS壳层已能有效钝化PbS量子点的表面缺陷、显著提高其光氧化稳定性.%PbS quantum dots (QDs) have enormous potential for applications ranging from tunable infrared lasers to solar cells due to their efficient emission over a large spectral range in the infrared.Especially,multiple exciton generation has been observed in PbS QDs,which makes PbS QDs have great potential for high-efficiency solar cells.However,these applications have been limited by instability in emission quantum yield and peak position on exposure to ambient conditions.An effective strategy to improve PbS QDs' stability is overgrowth with a shell of a more stable semiconductor,such as CdS,resulting in core/shell PbS/CdS QDs.The PbS/CdS QDs were fabricated in a two-step method.In the first step,PbS QDs with a 4.8 nm diameter were prepared by using organic metal.Second,PbS/CdS QDs with 3.8 nm PbS core and 0.5 nm CdS shell were fabricated by exposing PbS QDs in Cd2+ solution for 24 h at 65 ℃.In this article,cation exchange method was adopted to moderate reaction temperature in a low temperature,so that Ostwald ripening in high temperature was avoided.The results of transmission electron microscopy (TEM) and high resolution TEM showed that PbS QDs were sphere and in a cubic cystal without obvious

  10. Ion exchange synthesis and thermal characteristics of some $[\\text{N}^{+}_{2222}]$ based ionic liquids

    Indian Academy of Sciences (India)

    Vasishta D Bhatt; Kuldip Gohil

    2013-11-01

    Eight salts were obtained by reacting tetraethylammonium cation $[\\text{N}^{+}_{2222}]$ with inorganic anions like BF$^{-}_{4}$, NO$^{-}_{3}$, NO$^{-}_{2}$, SCN-, BrO$^{-}_{3}$, IO$^{-}_{3}$, PF$^{-}_{6}$ and HCO$^{-}_{3}$ using ion exchange method. These ionic liquids (ILs) were characterized using thermal methods, infrared spectroscopy and densitometry. Thermophysical properties such as density, coefficient of volume expansion, heat of fusion, heat capacity and thermal energy storage capacity were determined. Thermal conductivity of the samples was determined both in solid and liquid phases. Owing to high values of thermal energy storage capacity coupled with handsome liquid phase thermal conductivity, ILs under investigation were recommended as materials for thermal energy storage (TES) as well as heat transfer applications.

  11. Effects of ionizing radiation on modern ion exchange materials

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, S.F.; Pillay, K.K.S.

    1993-10-01

    We review published studies of the effects of ionizing radiation on ion exchange materials, emphasizing those published in recent years. A brief overview is followed by a more detailed examination of recent developments. Our review includes styrene/divinylbenzene copolymers with cation-exchange or anion-exchange functional groups, polyvinylpyridine anion exchangers, chelating resins, multifunctional resins, and inorganic exchangers. In general, strong-acid cation exchange resins are more resistant to radiation than are strong-base anion exchange resins, and polyvinylpyridine resins are more resistant than polystyrene resins. Cross-linkage, salt form, moisture content, and the surrounding medium all affect the radiation stability of a specific exchanger. Inorganic exchangers usually, but not always, exhibit high radiation resistance. Liquid ion exchangers, which have been used so extensively in nuclear processing applications, also are included.

  12. Controlling chemistry with cations: photochemistry within zeolites.

    Science.gov (United States)

    Ramamurthy, V; Shailaja, J; Kaanumalle, Lakshmi S; Sunoj, R B; Chandrasekhar, J

    2003-08-21

    The alkali ions present in the supercages of zeolites X and Y interact with included guest molecules through quadrupolar (cation-pi), and dipolar (cation-carbonyl) interactions. The presence of such interactions can be inferred through solid-state NMR spectra of the guest molecules. Alkali ions, as illustrated in this article, can be exploited to control the photochemical and photophysical behaviors of the guest molecules. For example, molecules that rarely phosphoresce can be induced to do so within heavy cation-exchanged zeolites. The nature (electronic configuration) of the lowest triplet state of carbonyl compounds can be altered with the help of light alkali metal ions. This state switch (n pi*-pi pi*) helps to bring out reactivity that normally remains dormant. Selectivity obtained during the singlet oxygen oxidation of olefins within zeolites illustrates the remarkable control that can be exerted on photoreactions with the help of a confined medium that also has active sites. The reaction cavities of zeolites, like enzymes, are not only well-defined and confined, but also have active sites that closely guide the reactant molecule from start to finish. The examples provided here illustrate that zeolites are far more useful than simple shape-selective catalysts.

  13. Sorption of organic cations to phyllosilicate clay minerals: CEC-normalization, salt dependency, and the role of electrostatic and hydrophobic effects.

    Science.gov (United States)

    Droge, Steven T J; Goss, Kai-Uwe

    2013-12-17

    Sorption to the phyllosilicate clay minerals Illite, kaolinite, and bentonite has been studied for a wide variety of organic cations using a flow-through method with fully aqueous medium as the eluent. Linear isotherms were observed at concentrations below 10% of the cation-exchange capacity (CEC) for Illite and kaolinite and below 1 mmol/kg (<1% CEC) for bentonite. Sorption to clays was strongly influenced by the electrolyte composition of the eluent but with a consistent trend for a diverse set of compounds on all clays, thus allowing for empirical correction factors. When sorption affinities for a given compound to a given clay are normalized to the CEC of the clay, the differences in sorption affinities between clays are reduced to less than 0.5 log units for most compounds. Although CEC-normalized sorption of quaternary ammonium compounds to clay was up to 10-fold higher than CEC-normalized sorption to soil organic matter, CEC-normalized sorption for most compounds was comparable between clays and soil organic matter. The clay fraction is thus a potentially relevant sorption phase for organic cations in many soils. The sorption data for organic cations to clay showed several regular trends with molecular structure but also showed quite a few systematic effects that we cannot explain. A model on the basis of the molecular size and charge density at the ionized nitrogen is used here as a tool to obtain benchmark values that elucidate the effect of specific polar moieties on the sorption affinity.

  14. Continuous elimination of Pb{sup 2+}, Cu{sup 2+}, Zn{sup 2+}, H{sup +} and NH{sub 4}{sup +} from acidic waters by ionic exchange on natural zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, Benjamin [E.T.S. Ingenieros de Minas, Universidad Politecnica de Madrid, Rios Rosas 21, 28003 Madrid (Spain); Canoira, Laureano, E-mail: laureano.canoira.lopez@upm.es [E.T.S. Ingenieros de Minas, Universidad Politecnica de Madrid, Rios Rosas 21, 28003 Madrid (Spain); Morante, Fernando, E-mail: fmorante@espol.edu.ec [Instituto de Ciencias Quimicas y Ambientales, Escuela Superior Politecnica del Litoral, P.O. Box 09-01-5863, Guayaquil (Ecuador); Martinez-Bedia, Jose M.; Vinagre, Carlos; Garcia-Gonzalez, Jeronimo-Emilio [E.T.S. Ingenieros de Minas, Universidad Politecnica de Madrid, Rios Rosas 21, 28003 Madrid (Spain); Elsen, Jan, E-mail: jan.elsen@geo.kuleuven.be [Physico-Chemische Geologie, Katholieke Universiteit Leuven, Celestijnenlaan 200E, B-3001, Heverlee (Belgium); Alcantara, Ramon [E.T.S. Ingenieros de Minas, Universidad Politecnica de Madrid, Rios Rosas 21, 28003 Madrid (Spain)

    2009-07-30

    A study of breakthrough curves for cations usually found in acid mine drainage (Pb{sup 2+}, Cu{sup 2+}, Zn{sup 2+} and H{sup +}) and municipal wastewater (NH{sub 4}{sup +}) have been conducted on some natural zeolitic tuffs. The zeolitic tuffs used in this study are: three zeolitic tuffs from Cayo Formation, Guayaquil (Ecuador), characterized by X-ray diffraction as clinoptilolite (sample CLI-1) and heulandite (samples HEU-1 and HEU-2)-rich tuffs, and two zeolitic tuffs from Parnaiba Basin, Belem do Para (Brazil), characterized as stilbite-rich tuffs (samples STI-1 and STI-2). The clinoptilolite sample CLI-1 shows an exceedingly good exchange capacities for Pb{sup 2+} and NH{sub 4}{sup +} as received, and also a very high exchange capacity for Cu{sup 2+} and Zn{sup 2+} when conditioned with 2 M sodium chloride, with much higher values than those reported in the literature for other clinioptilolite ores. A general order of effective cation exchange capacity could be inferred from breakthrough curves on these zeolitic tuffs: CLI-1>HEU-2>HEU-1>STI-2 Since it is true for most of the cations studied.

  15. Silica surfaces lubrication by hydrated cations adsorption from electrolyte solutions.

    Science.gov (United States)

    Donose, Bogdan C; Vakarelski, Ivan U; Higashitani, Ko

    2005-03-01

    Adsorption of hydrated cations on hydrophilic surfaces has been related to a variety of phenomena associated with the short-range interaction forces and mechanisms of the adhesive contact between the surfaces. Here we have investigated the effect of the adsorption of cations on the lateral interaction. Using lateral force microscopy (LFM), we have measured the friction force between a silica particle and silica wafer in pure water and in electrolyte solutions of LiCl, NaCl, and CsCl salts. A significant lubrication effect was demonstrated for solutions of high electrolyte concentrations. It was found that the adsorbed layers of smaller and more hydrated cations have a higher lubrication capacity than the layers of larger and less hydrated cations. Additionally, we have demonstrated a characteristic dependence of the friction force on the sliding velocity of surfaces. A mechanism for the observed phenomena based on the microstructures of the adsorbed layers is proposed.

  16. Carrying Capacity

    DEFF Research Database (Denmark)

    Schroll, Henning; Andersen, Jan; Kjærgård, Bente

    2012-01-01

    A spatial planning act was introduced inIndonesia 1992 and renewed in 2008. It emphasised the planning role of decentralised authorities. The spatial planning act covers both spatial and environmental issues. It defines the concept of carrying capacity and includes definitions of supportive...... carrying capacity (SCC) and assimilative carrying capacity (ACC). The act mandates that the latter two aspects must be taken into consideration in the local spatial plans. The present study aimed at developing a background for a national guideline for carrying capacity in Indonesian provinces and districts...... standard or governmental political objective exists. In most cases it was possible to select a set of indicators, including thresholds that are workable in a carrying capacity planning at the local administrative levels. Not all relevant sectors at the decentralized level were included. Indicators of SCC...

  17. Tunable separation of anions and cations by column switching in ion chromatography.

    Science.gov (United States)

    Amin, Muhammad; Lim, Lee Wah; Takeuchi, Toyohide

    2007-03-15

    A convenient ion chromatography method has been proposed for the routine and simple determination of anions (Cl(-), SO(4)(2-) and NO(3)(-)) and/or cations (Na(+), NH(4)(+), K(+), Mg(2+) and Ca(2+)) using a single pump, a single eluent and a single detector. The present system used cation-exchange and anion-exchange columns connected in series via two 6-port switching valves or a single 10-port valve. The connection order of the ion-exchange columns could be varied by switching the valve(s). The present system therefore allowed the separation of either cations or anions in a single chromatographic run. While one ion-exchange column is being operated, the other ion-exchange column is being conditioned, i.e., the columns are always ready for analysis at any time. When 2.4mM 5-sulfosalicylic acid was used as the eluent, the three anions and the five cations could be separated on the anion-exchange column and cation-exchange column, respectively. In order to obtain the separations of the target ions, the injection valve was placed between the two columns. Complete separations of the above anions or cations were demonstrated within 10min each. The detection limits at S/N=3 were 19-50ppb (mug/l) for cations and 10-14ppb for anions. The relative standard deviations of the analyte ions were less than 1.1, 2.9 and 2.8% for retention time, peak area and peak height, respectively. This proposed technique was applied to the determination of common anions and cations in river water samples.

  18. Hydrothermal Synthesis of Zeolite P From Fly Ash and Its Exchange Capacity to Ca2+%粉煤灰制备P型分子筛及对Ca2+交换能力的研究

    Institute of Scientific and Technical Information of China (English)

    孟桂花; 吴建宁; 刘志勇; 张玲

    2015-01-01

    以粉煤灰为原材料,微波法合成P型分子筛,考察了硅铝摩尔比、pH值、晶化时间等不同条件的影响,得到最佳工艺:n( SiO2)/n(Al2O3)=4.1, pH值12,晶化时间10min。P型分子筛的钙交换能力为442.46mg CaCO3/g。红外光谱表明产品符合分子筛的骨架振动谱带特征,扫描电镜表明产品晶型较好而且粒度均匀,X射线衍射表明特征峰基本与标准特征峰相似。%ZeoliteP was synthesizedfromsolid waste flyashbymicrowave method. The effect ofsilicon aluminum molar ratio, pH value, crystallization timeand otherconditionswas investigated,and the optimum reaction conditions were obtained as follows:n(SiO2)/n(Al2O3) = 4.1, pH value is 12, crystallization time is 10min.PreparedzeoliteP exchange capacity to Ca2+is 442.46mgCaCO3/g,infraredspectroscopy show that theproducts comply with bands of molecular sieve, SEM showsthat the products haveuniformparticle size,X-ray diffraction showsthat the characteristic peaks ofthe productsaresimilar with standardmolecular sieve.

  19. Adsorption characteristics of humic acid-immobilized amine modified polyacrylamide/bentonite composite for cationic dyes in aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    T. S. Anirudhan; P. S. Suchithra

    2009-01-01

    Humic acid-immobilized amine modified polyacrylamide/bentonite composite (HA-Am-PAA-B) was prepared and used as an adsorbent for the adsorption of cationic dyes (Malachite Green (MG), Methylene Blue (MB) and Crystal Violet (CV)) from aqueous solutions. The polyacrylamide/bentonite composite (PAA-B) was prepared by intercalative polymerization of acrylamide with Na-bentonite in the presence of N,N'-methylenebisacrylamide as a crosslinking agent and hexamethylenediammine as propagater. PAA-B was subsequently treated with ethylenediammine to increase its loading capacity for HA. The surface characterizations of the adsorbent were investigated. The adsorbent behaved like a cation exchanger and more than 99.0% removal of dyes was detected at pH range 6.0-8.0. The capacity of HA-Am-PAA-B was found to decrease in the following order: MG > MB > CV. The kinetic and isotherm data were interpreted by pseudo-second order rate equation and Freundlich isotherm model, respectively. Experiments were carried out using binary solute systems to assess the competitive adsorption phenomenon. The experimental isotherm data for each binary solute combination of MG, MB and CV were analyzed using Sheindrof-Rebhun-Sheintuch (SRS) (multicomponent Freundlich type) equation.

  20. Computer simulation of alkali metal cation-montmorillonite hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Fang-Ru Chou [Columbia Univ., Palisades, NY (United States); Skipper, N.T. [Univ. College, London (United Kingdom); Sposito, G. [Lawrence Berkeley National Lab., CA (United States)

    1997-12-31

    Molecular structure in the interlayers of Li-, Na-, or K-Wyoming montmorillonite with one, two, or three adsorbed water layers was investigated for the first time by concurrent Monte Carlo and molecular dynamics (MD) simulation, based on the Matsouka-Clementi-Yoshimine, (MCY) model of water-water interactions. Calculated layer spacings, as well as interlayer-species self-diffusion coefficients, were in good agreement with available experimental data. Inner-sphere surface complexes of the cations with tetrahedral charge sites were observed for all hydrates, whereas outer-sphere surface complexes of the cations with octahedral charge sites, found also in the one-layer hydrate, tended to dissociate from the clay mineral basal planes into a diffuse layer in the two- and three-layer hydrates. Differences in the interlayer water structure among the hydrates mainly reflected cation solvation, although some water molecules were entrapped within cavities in the montmorillonite surface. All of the interlayer cation and water species exchanged on the time scale (0.2 ns) of the MD simulations. Comparisons with results obtained using, instead of the MCY model, the TIP4P model for water-water, cation-water, and cation-clay interactions indicated that layer spacings and interlayer species mobilities tend to be under-predicted by the TIP4P model.

  1. 17 CFR 3.4 - Registration in one capacity not included in registration in any other capacity.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Registration in one capacity not included in registration in any other capacity. 3.4 Section 3.4 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION REGISTRATION Registration § 3.4 Registration in one capacity...

  2. Cation-{pi}-interaction promoted aggregation of aromatic molecules and energy transfer within Y zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, K.J.; Sunoj, R.B.; Chandrasekhar, J.; Ramamurthy, V.

    2000-05-30

    Photophysical studies of naphthalene confirm that aromatic molecules tend to aggregate within cation exchanged Y zeolites. Ground-state aggregation is traced to the presence of cation-aromatic {pi}-interaction. Solvents that can coordinate to the cation turn off the cation-aromatic interaction, and consequently aggregation does not occur in zeolites that are impregnated with the above solvents. The solvent that exhibits a maximum in such an effect is water. MP2 calculations on cation-benzene dimer indicate that cation-{pi}-interaction results in stabilization of the {pi}-stacked benzene dimer. Results of MP2 calculations are consistent with the formation of ground-state {pi}-stacked aggregates of naphthalene molecules within Y zeolites.

  3. 基于温度和热容流率同时变化的有分流换热网络弹性设计的研究%Synthesis of Flexible Heat Exchanger Networks with Stream Splits Based on Rangers of Stream Supply Temperatures and Heat Capacity Flowrates

    Institute of Scientific and Technical Information of China (English)

    李志红; 罗行; 华贲; W.Roetzel

    2004-01-01

    A new superstructure model of heat exchanger networks (HEN) with stream splits based on rangers of streams supply temperatures and heat capacity flow rates is presented. The simultaneous optimal mathematical model of flexible HEN synthesis is established too. Firstly, the streams with rangers of supply temperatures and/or the streams with the rangers of heat capacity flow rates are pretreated; Secondly, several rules are proposed to establish the superstructure model of HEN with splits and the simultaneous optimal mathematical model of flexible HEN; Thirdly, the improving genetic algorithm is applied to solve the mathematical model established at the second step effectively, and the original optimal structure of HEN based on the maximum operation limiting condition can be obtained easily; Finally, the rules of heat exchange unit merged and the heat load of heat exchanger relaxed are presented, the flexible configuration of HEN satisfied the operation condition between the upper and down bounds of supply temperature and heat capacity flow rates can be obtained based on the original optimal structure of HEN by means of these rules. A case study demonstrates the method presented in this paper is effective

  4. Catalysis using hydrous metal oxide ion exchanges

    Science.gov (United States)

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  5. Catalysis using hydrous metal oxide ion exchangers

    Science.gov (United States)

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  6. Removal of charged micropollutants from water by ion-exchange polymers -- effects of competing electrolytes.

    Science.gov (United States)

    Bäuerlein, Patrick S; Ter Laak, Thomas L; Hofman-Caris, Roberta C H M; de Voogt, Pim; Droge, Steven T J

    2012-10-15

    A wide variety of environmental compounds of concern, e.g. pharmaceuticals or illicit drugs, are acids or bases that may predominantly be present as charged species in drinking water sources. These charged micropollutants may prove difficult to remove by currently used water treatment steps (e.g. UV/H(2)O(2), activated carbon (AC) or membranes). We studied the sorption affinity of some ionic organic compounds to both AC and different charged polymeric materials. Ion-exchange polymers may be effective as additional extraction phases in water treatment, because sorption of all charged compounds to oppositely charged polymers was stronger than to AC, especially for the double-charged cation metformin. Tested below 1% of the polymer ion-exchange capacity, the sorption affinity of charged micropollutants is nonlinear and depends on the composition of the aqueous medium. Whereas oppositely charged electrolytes do not impact sorption of organic ions, equally charged electrolytes do influence sorption indicating ion-exchange (IE) to be the main sorption mechanism. For the tested polymers, a tenfold increased salt concentration lowered the IE-sorption affinity by a factor two. Different electrolytes affect IE with organic ions in a similar way as inorganic ions on IE-resins, and no clear differences in this trend were observed between the sulphonated and the carboxylated cation-exchanger. Sorption of organic cations is five fold less in Ca(2+) solutions compared to similar concentrations of Na(+), while that of anionic compounds is three fold weaker in SO(4)(2-) solutions compared to equal concentrations of Cl(-).

  7. [Antioxidant activity of cationic whey protein isolate].

    Science.gov (United States)

    titova, M E; Komolov, S A; Tikhomirova, N A

    2012-01-01

    The process of lipid peroxidation (LPO) in biological membranes of cells is carried out by free radical mechanism, a feature of which is the interaction of radicals with other molecules. In this work we investigated the antioxidant activity of cationic whey protein isolate, obtained by the cation-exchange chromatography on KM-cellulose from raw cow's milk, in vitro and in vivo. In biological liquids, which are milk, blood serum, fetal fluids, contains a complex of biologically active substances with a unique multifunctional properties, and which are carrying out a protective, antimicrobial, regenerating, antioxidant, immunomodulatory, regulatory and others functions. Contents of the isolate were determined electrophoretically and by its biological activity. Cationic whey protein isolate included lactoperoxidase, lactoferrin, pancreatic RNase, lysozyme and angeogenin. The given isolate significantly has an antioxidant effect in model experimental systems in vitro and therefore may be considered as a factor that can adjust the intensity of lipid oxidation. In model solutions products of lipid oxidation were obtained by oxidation of phosphatidylcholine by hydrogen peroxide in the presence of a source of iron. The composition of the reaction mixture: 0,4 mM H2O2; 50 mcM of hemin; 2 mg/ml L-alpha-phosphatidylcholine from soybean (Sigma, German). Lipid peroxidation products were formed during the incubation of the reaction mixture for two hours at 37 degrees C. In our studies rats in the adaptation period immediately after isolation from the nest obtained from food given orally native cationic whey protein isolate at the concentration three times higher than in fresh cow's milk. On the manifestation of the antioxidant activity of cationic whey protein isolate in vivo evidence decrease of lipid peroxidation products concentration in the blood of rats from the experimental group receipt whey protein isolate in dos 0,6 mg/g for more than 20% (pwhey protein isolate has an

  8. Synthesis and application of Polymer-encapsulated Zirconia-based cation exchange packing for SPE%聚合物/氧化锆基质阳离子交换固相萃取填料的研制及应用

    Institute of Scientific and Technical Information of China (English)

    江艳; 申书昌; 柳玉辉; 辛建娇

    2012-01-01

    In this paper, zirconia powder synthetized was treated by vinyl-silane coupling agent to get vinyl modified zirconia.The SPE packing of cross-linked polystyrene encapsulated zirconia-base was synthesized by styrene,divinylbenzene and vinyl-modified zirconia in radical polymerization. The polystyrene encapsulated zirconia-based was sulfonated by concentrated sulfuric acid and the cation exchange packing of for solid phase extraction was prepared.The composition and structure of the meterial were characterized by FT- IR, SEM and XRD.The reliability of detection method and adsorption properties of SPE columns were investigated by detecting the content of the sulfamerazine and sulfamethazine in the water on basis of SPE-HPLC, and the results were satisfied.%制备了ZrO2纳米粉体,并使用硅烷偶联剂处理得到乙烯基二氧化锆。通过自由基聚合,苯乙烯、二乙烯基苯与二氧化锆颗粒表面乙烯基反应,将交联聚苯乙烯包覆在锆胶表面上,再经硫酸磺化,制得聚合物/氧化锵阳离子交换同相萃取柱填料。采用Fr-IR和TEM手段表征了合成材料的组成与结构。通过固相萃取与高效液相色谱联用测定了水溶液中磺胺甲基嘧啶和磺胺二甲基嘧啶,考察了该固相萃取小柱的吸附性能及测试方法的可靠性,结果令人满意。

  9. Thermodynamics of cationic surfactant sorption onto natural clinoptilolite

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, E.J.; Bowman, R.S. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States); Carey, J.W. [Los Alamos National Lab., NM (United States)

    1998-10-15

    Sorption enthalpies of hexadecyltrimethylammonium bromide (HDTMA) as monomers and micelles and tetraethylammonium bromide (TEA) were used with surfactant, counterion, and co-ion sorption isotherms to infer the conformation, sorption mechanism, and relative stability of the sorbed surfactants on natural clinoptilolite. The average value of the sorption enthalpy was {minus}10.38 kJ/mol for monomers, {minus}11.98 kJ/mol for micelles, and +3.03 kJ/mol for TEA. Sorption of monomers produced a lower sorption plateau than equivalent micelle sorption (maxima 145 mmol/kg, 225 mmol/kg). Analysis of the sorption data demonstrated a change in the sorption mechanism at the external cation exchange capacity (ECEC) of clinoptilolite. Sorption data from below and above the ECEC were fit to a simple polynomial model and the Gibbs free energy of sorption ({Delta} G{sub m}{sup 0}) and sorption entropies were calculated. Resultant values of {Delta} G{sub m}{sup 0} were {minus}9.27 and {minus}14.38 kJ/mol for HDTMA monomers and micelles, respectively, for sorption below the ECEC, and {minus}16.11 and {minus}23.10 kJ/mol, respectively, for sorption above the ECEC. The value for TEA was {minus}1.04 kJ/mol, indicating weaker sorption than for HDTMA. Monomer sorption to clinoptilolite exceeded the ECEC, even when the solution concentration was below the critical micelle concentration. Hydrophobic (tail-tail) components of {Delta} G{sub m}{sup 0} were the driving force for sorption of HDTMA, both below and above the ECEC. A significant kinetic effect was observed in the sorption isotherms with a period of rapid sorption followed by slow equilibration requiring 7 days to achieve steady state for HDTMA; TEA equilibration occurred within 24 h.

  10. PHOTOOXIDATION OF TOLUENE IN CATION-EXCHANGED ZEOLITES. (R825304)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  11. Exploring Alkaline Stable Organic Cations for Polymer Hydroxide Exchange Membranes

    Science.gov (United States)

    2015-04-29

    was stirred at room temperature for 24 h. The solution was added dropwise to 40 mL ethyl ether to precipitate the product . The precipitate was...area of MTPP-(2,6-MeO); A3 is the peak area of ether hydrolysis products . ................................................. 163   Figure C.5...A2 is the peak area of BTPP-(2,6-MeO); A3 is the peak area of ether hydrolysis products . ................................................. 164

  12. Synthetic cation-selective nanotube: Permeant cations chaperoned by anions

    Science.gov (United States)

    Hilder, Tamsyn A.; Gordon, Dan; Chung, Shin-Ho

    2011-01-01

    The ability to design ion-selective, synthetic nanotubes which mimic biological ion channels may have significant implications for the future treatment of bacteria, diseases, and as ultrasensitive biosensors. We present the design of a synthetic nanotube made from carbon atoms that selectively allows monovalent cations to move across and rejects all anions. The cation-selective nanotube mimics some of the salient properties of biological ion channels. Before practical nanodevices are successfully fabricated it is vital that proof-of-concept computational studies are performed. With this in mind we use molecular and stochastic dynamics simulations to characterize the dynamics of ion permeation across a single-walled (10, 10), 36 Å long, carbon nanotube terminated with carboxylic acid with an effective radius of 5.08 Å. Although cations encounter a high energy barrier of 7 kT, its height is drastically reduced by a chloride ion in the nanotube. The presence of a chloride ion near the pore entrance thus enables a cation to enter the pore and, once in the pore, it is chaperoned by the resident counterion across the narrow pore. The moment the chaperoned cation transits the pore, the counterion moves back to the entrance to ferry another ion. The synthetic nanotube has a high sodium conductance of 124 pS and shows linear current-voltage and current-concentration profiles. The cation-anion selectivity ratio ranges from 8 to 25, depending on the ionic concentrations in the reservoirs.

  13. Synthesis and SMM behaviour of trinuclear versus dinuclear 3d-5f uranyl(v)-cobalt(ii) cation-cation complexes.

    Science.gov (United States)

    Chatelain, Lucile; Tuna, Floriana; Pécaut, Jacques; Mazzanti, Marinella

    2017-01-17

    Trinuclear versus dinuclear heterodimetallic U(V)O2(+)Co(2+) complexes were selectively assembled via a cation-cation interaction by tuning the ligand. The trimeric complex 2, with a linear [Co-O[double bond, length as m-dash]U[double bond, length as m-dash]O-Co] core, exhibits magnetic exchange and slow relaxation with a reversal barrier of 30.5 ± 0.9 K providing the first example of a U-Co exchange-coupled SMM.

  14. Cation binding to 15-TBA quadruplex DNA is a multiple-pathway cation-dependent process.

    Science.gov (United States)

    Reshetnikov, Roman V; Sponer, Jiri; Rassokhina, Olga I; Kopylov, Alexei M; Tsvetkov, Philipp O; Makarov, Alexander A; Golovin, Andrey V

    2011-12-01

    A combination of explicit solvent molecular dynamics simulation (30 simulations reaching 4 µs in total), hybrid quantum mechanics/molecular mechanics approach and isothermal titration calorimetry was used to investigate the atomistic picture of ion binding to 15-mer thrombin-binding quadruplex DNA (G-DNA) aptamer. Binding of ions to G-DNA is complex multiple pathway process, which is strongly affected by the type of the cation. The individual ion-binding events are substantially modulated by the connecting loops of the aptamer, which play several roles. They stabilize the molecule during time periods when the bound ions are not present, they modulate the route of the ion into the stem and they also stabilize the internal ions by closing the gates through which the ions enter the quadruplex. Using our extensive simulations, we for the first time observed full spontaneous exchange of internal cation between quadruplex molecule and bulk solvent at atomistic resolution. The simulation suggests that expulsion of the internally bound ion is correlated with initial binding of the incoming ion. The incoming ion then readily replaces the bound ion while minimizing any destabilization of the solute molecule during the exchange.

  15. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    and KCN, are selectively bound to the catalyst, providing exceptionally high enantioselectivities for kinetic resolutions, elimination reactions (fluoride base), and Strecker synthesis (cyanide nucleophile). Asymmetric cation-binding catalysis was recently expanded to silicon-based reagents, enabling...... solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...

  16. Characterization of cross-linked cellulosic ion-exchange adsorbents: 2. Protein sorption and transport.

    Science.gov (United States)

    Angelo, James M; Cvetkovic, Aleksandar; Gantier, Rene; Lenhoff, Abraham M

    2016-03-18

    Adsorption behavior in the HyperCel family of cellulosic ion-exchange materials (Pall Corporation) was characterized using methods to assess, quantitatively and qualitatively, the dynamics of protein uptake as well as static adsorption as a function of ionic strength and protein concentration using several model proteins. The three exchangers studied all presented relatively high adsorptive capacities under low ionic strength conditions, comparable to commercially available resins containing polymer functionalization aimed at increasing that particular characteristic. The strong cation- and anion-exchange moieties showed higher sensitivity to increasing salt concentrations, but protein affinity on the salt-tolerant STAR AX HyperCel exchanger remained strong at ionic strengths normally used in downstream processing to elute material fully during ion-exchange chromatography. Very high uptake rates were observed in both batch kinetics experiments and time-series confocal laser scanning microscopy, suggesting low intraparticle transport resistances relative to external film resistance, even at higher bulk protein concentrations where the opposite is typically observed. Electron microscopy imaging of protein adsorbed phases provided additional insight into particle structure that could not be resolved in previous work on the bare resins.

  17. Mono- and polyprotic buffer systems in anion exchange chromatography of influenza virus particles.

    Science.gov (United States)

    Vajda, Judith; Weber, Dennis; Stefaniak, Sabine; Hundt, Boris; Rathfelder, Tanja; Müller, Egbert

    2016-05-27

    Different ions typically used in downstream processing of biologicals are evaluated for their potential in anion exchange chromatography of an industrially produced, pandemic influenza H1N1 virus. Capacity, selectivity and recovery are investigated based on single step elution parallel chromatography experiments. The inactivated H1N1 feedstream is produced in Madin-Darby Bovine Kidney cells. Interesting effects are found for sodium phosphate and sodium citrate. Both anions are triprotic kosmotropes. Anion exchange chromatography generally offers high scalability to satisfy sudden demands for vaccines, which may occur in case of an emerging influenza outbreak. Appropriate pH conditions for H1N1 adsorption are determined by Zeta potential measurements. The dynamic binding capacity of a salt tolerant polyamine-type resin is up to 6.4 times greater than the capacity of a grafted Q-type resin. Pseudo-affinity interactions of polyamines with the M2 protein of influenza may contribute to the obtained capacity increase. Both resins achieve greater capacity in sodium phosphate buffer compared to Tris/HCl. A recovery of 67% and DNA clearance close to 100% without DNAse treatment are achieved for the Q-type resin. Recovery of the virus from the salt tolerant resin requires the use of polyprotic acids in the elution buffer. 85% of the DNA and 60% of the proteins can be removed by the salt tolerant resin. The presence of sodium phosphate during anion exchange chromatography seems to support stability of the H1N1 particles in presence of hydrophobic cations.

  18. Multiproduct high-resolution monoclonal antibody charge variant separations by pH gradient ion-exchange chromatography.

    Science.gov (United States)

    Farnan, Dell; Moreno, G Tony

    2009-11-01

    In the biotechnology industry, ion-exchange chromatography is widely used for profiling the charge heterogeneity of proteins, including monoclonal antibodies. Ionic strength based ion exchange separations, while having excellent resolving power and robustness, are product specific and time-consuming to develop. In the present work, a pH gradient based separation using a cation exchange column is described and shown to be a multiproduct charge sensitive separation method for monoclonal antibodies. Simple mixtures of defined buffer components were used to generate the pH-gradients that separate closely related antibody species. The form of the pH gradient was controlled and optimized by the pump as well as the buffer composition if necessary. During this work, the buffer compositions for the separation were optimized in parallel for several MAbs. The data shows that the multiproduct method is optimal for all of the MAbs studied. Operational aspects of the separation such as column chemistry, column length, and sample matrix indicate a very robust method. The pH gradient ion-exchange method is demonstrated to have significant resolving power and peak capacities far in excess of what we would expect for ionic strength elution ion-exchange. Data obtained demonstrates that the separation is relatively insensitive to column length. Direct analysis (no buffer exchange) of samples in matrixes consistent with in-process manufacturing pools is demonstrated. Such a capability is extremely useful for the high throughput evaluation of in-process and final product samples.

  19. 阳离子交换树脂催化制备纳米纤维素晶体的谱学性能与流变行为%Spectrum and Rheological Properties of Nanocellulose Crystal Prepared with Cation Exchange Resin

    Institute of Scientific and Technical Information of China (English)

    唐丽荣; 黄彪; 戴达松; 欧文; 李涛; 周东东; 陈学榕

    2011-01-01

    采用强酸型阳离子交换树脂在超声波辅助作用下制备了纳米纤维素晶体(NCC).采用场发射环境扫描电子显微镜(ESEM-FEG)、场发射透射电子显微镜(HR-TEM)、X射线粉末衍射仪(XRD)、傅利叶红外光谱仪(FT-IR)和转子式流变仪对所制备NCC的形貌、谱学和流变学行为进行了研究.结果表明,所制备NCC为近球形,颗粒尺寸约为25nm~50nm,样品属于纤维素Ⅰ型,结晶度为84.26%,晶粒平均由6个晶胞组成.由FT-IR分析可知,NCC仍具有纤维素的基本化学结构.NCC胶体为剪切变稀的假塑性流体,随着温度的升高,其黏度逐渐减小,并最终趋于平缓,结果表明NCC胶体具有较好的稳定性.%Nanocellulose crystal (NCC) was prepared by ultrasonic-assisted hydrolysis with strong acidic cation exchange resin. The size and morphology, crystal structure, spectrum properties and rheological behavior of nanocellulose crystal were investigated by field emission gun environment scanning electron microscopes (ESEM-FEG), field emission transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry(FT-IR) and rotor rheometer. The results indicate that the nanocellulose crystal is spherical and the size is about 25 nm~50 nm. The samples have the crystalline cellulose I structure, the crystallinity is 84.26% , and the grain is composed of 6 unit crystal cell. Moreover, the results of FT-IR show that NCC still has the basic chemical structure of cellulose. NCC is the shear thinned pseudoplastic fluid. Futhermore, as the temperature increases, its viscosity decreases, and gradually tends to flat, the results indicate that the samples enjoy nice stability.

  20. Preparação e propriedades de zeólitas faujasita contendo cátions amônio Preparation and properties of faujasite zeolites containing ammonium cations

    Directory of Open Access Journals (Sweden)

    Karina Arruda Almeida

    2010-01-01

    Full Text Available Sodium faujasite zeolites with Si/Al ratio of 1.4 and 2.5 were exchanged with methylammonium cations. The influence of framework aluminum and ion exchange degree in their basic properties were evaluated. These properties were assessed in the Knoevenagel catalytic condensation. The sodium ion exchange was restricted to the supercavity and the exchange degree depended on the cation volume and on the Si/Al ratio. The higher catalytic activity is achieved for the zeolite with the lower Si/Al ratio exchanged with the monomethylammonium cation. The best performance of this catalyst is attributed to the higher basicity in combination with elevated micropore volume.

  1. Capacity and Capacity Utilization in Fishing Industries

    OpenAIRE

    Kirkley, James E; Squires, Dale

    1999-01-01

    Excess capacity of fishing fleets is one of the most pressing problems facing the world's fisheries and the sustainable harvesting of resource stocks. Considerable confusion persists over the definition and measurement of capacity and capacity utilization in fishing. Fishing capacity and capacity utilization, rather than capital (or effort) utilization, provide the appropriate framework. This paper provides both technological-economic and economic definitions of capacity and excess capacity i...

  2. Summary on running of capacity-expanded and reformed ion-exchange membrane electrolyzesr%离子膜法电解槽扩能改造后的运行总结

    Institute of Scientific and Technical Information of China (English)

    王记孝; 田玉英

    2013-01-01

    陕西金泰氯碱化工有限公司旭化成电解槽换离子膜后电解槽电压上升,吨碱电耗增加,电流效率下降。从二次盐水品质、进槽盐酸控制、停车次数及离子膜本身的老化、单元槽和离子膜运行时间等角度,分析了槽电压上升、电流效率下降的原因,为电解槽系统改造提供了有力的证据。%After Shaanxi Jintai Chlor -Alkali Chemical Industry Co ., Ltd.changed the ion -exchange membranes for Asahi Kasei ion -exchange membrane electrolyzers , the cell voltage increased the unit electricity consumption for production of caustic soda increased , and the current efficiency decreased .The causes were analyzed in terms of the quality of secondary brine , the control of hydrochloric acid fed into electrolyzers , shutdown times , the aging of ion-exchange membranes , and the running time of unit cells and ion -exchange membranes .Thus, better evidence was provided for the transform of electrolyzer system .

  3. THERMODYNAMICS OF ION-EXCHANGED NATURAL CLINOPTILOLITE

    Science.gov (United States)

    Natural clinoptilolite from Castle Creek, Idaho, and its cation-exchanged variants (Na-Cpt, NaK-Cpt, K-Cpt, and Ca-Cpt) were studied by high-temperature calorimetry. The hydration enthalpy for all clinoptilolites is about -30 kJ/mol H2O (liquid water reference state) at 25 C. T...

  4. Properties of powdered ion-exchange resins based on petroleum asphaltites

    Energy Technology Data Exchange (ETDEWEB)

    Pokonova, Y.V.; Mitrofanova, L.M.; Proskuryakov, V.A.

    1977-02-01

    The following properties of the resins were studied: physical-mechanical properties, total effective exchange capacity, particle size distribution, dissociation constants, and dynamic and static exchange capacities. 6 tables. (DLC)

  5. Bifunctional Crosslinking Agents Enhance Anion Exchange Membrane Efficacy for Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Wang, Wenpin; Xu, Min; Wang, Shubo; Xie, Xiaofeng; Lv, Yafei; Ramani, Vijay K

    2014-06-01

    A series of cross-linked fluorinated poly (aryl ether oxadiazole) membranes (FPAEOM) derivatized with imidazolium groups were prepared. Poly (N-vinylimidazole) (PVI) was used as the bifunctional cross-linking agent to: a) lower vanadium permeability, b) enhance dimensional stability, and c) concomitantly provide added ion exchange capacity in the resultant anion exchange membranes. At a molar ratio of PVI to FPAEOM of 1.5, the resultant membrane (FPAEOM-1.5 PVI) had an ion exchange capacity of 2.2 meq g-1, a vanadium permeability of 6.8×10-7 cm2 min-1, a water uptake of 68 wt.%, and an ionic conductivity of 22.0 mS cm-1, all at 25°C. Single cells prepared with the FPAEOM-1.5 PVI membrane exhibited a higher coulombic efficiency (> 92%) and energy efficiency (> 86%) after 40 test cycles in vanadium redox flow battery. The imidazolium cation showed high chemical stability in highly acidic and oxidizing vanadium solution as opposed to poor stability in alkaline solutions. Based on our DFT studies, this was attributed to the lower HOMO energy (-7.265 eV) of the HSO4- ion (compared to the OH- ion; -5.496 eV) and the larger HOMO-LUMO energy gap (6.394 eV) of dimethylimidazolium bisulfate ([DMIM] [HSO4]) as compared to [DMIM] [OH] (5.387 eV).

  6. Phosphate removal and recovery from water using nanocomposite of immobilized magnetite nanoparticles on cationic polymer.

    Science.gov (United States)

    Abo Markeb, Ahmad; Alonso, Amanda; Dorado, Antonio David; Sánchez, Antoni; Font, Xavier

    2016-08-01

    A novel nanocomposite (NC) based on magnetite nanoparticles (Fe3O4-NPs) immobilized on the surface of a cationic exchange polymer, C100, using a modification of the co-precipitation method was developed to obtain magnetic NCs for phosphate removal and recovery from water. High-resolution transmission electron microscopy-energy-dispersive spectroscopy, scanning electron microscopy , X-ray diffraction, and inductively coupled plasma optical emission spectrometry were used to characterize the NCs. Continuous adsorption process by the so-called breakthrough curves was used to determine the adsorption capacity of the Fe3O4-based NC. The adsorption capacity conditions were studied under different conditions (pH, phosphate concentration, and concentration of nanoparticles). The optimum concentration of iron in the NC for phosphate removal was 23.59 mgFe/gNC. The sorption isotherms of this material were performed at pH 5 and 7. Taking into account the real application of this novel material in real water, the experiments were performed at pH 7, achieving an adsorption capacity higher than 4.9 mgPO4-P/gNC. Moreover, Freundlich, Langmuir, and a combination of them fit the experimental data and were used for interpreting the influence of pH on the sorption and the adsorption mechanism for this novel material. Furthermore, regeneration and reusability of the NC were tested, obtaining 97.5% recovery of phosphate for the first cycle, and at least seven cycles of adsorption-desorption were carried out with more than 40% of recovery. Thus, this work described a novel magnetic nanoadsorbent with properties for phosphate recovery in wastewater.

  7. Divergent responses of soil buffering capacity to long-term N deposition in three typical tropical forests with different land-use history.

    Science.gov (United States)

    Lu, Xiankai; Mao, Qinggong; Mo, Jiangming; Gilliam, Frank S; Zhou, Guoyi; Luo, Yiqi; Zhang, Wei; Huang, Juan

    2015-04-01

    Elevated anthropogenic nitrogen (N) deposition has become an important driver of soil acidification at both regional and global scales. It remains unclear, however, how long-term N deposition affects soil buffering capacity in tropical forest ecosystems and in ecosystems of contrasting land-use history. Here, we expand on a long-term N deposition experiment in three tropical forests that vary in land-use history (primary, secondary, and planted forests) in Southern China, with N addition as NH4NO3 of 0, 50, 100, and 150 kg N ha(-1) yr(-1), respectively. Results showed that all three forests were acid-sensitive ecosystems with poor soil buffering capacity, while the primary forest had higher base saturation and cation exchange capacity than others. However, long-term N addition significantly accelerated soil acidification and decreased soil buffering capacity in the primary forest, but not in the degraded secondary and planted forests. We suggest that ecosystem N status, influenced by different land-use history, is primarily responsible for these divergent responses. N-rich primary forests may be more sensitive to external N inputs than others with low N status, and should be given more attention under global changes in the future, because lack of nutrient cations is irreversible.

  8. 压水堆余热排出换热器性能研究%Numerical Investigation of Residual Heat Removal Heat Exchange Capacity in Pressurized Water Reactor Plants

    Institute of Scientific and Technical Information of China (English)

    丘锦萌; 李军; 王晓江; 王志刚

    2013-01-01

    以压水堆余热排出系统为对象,建立管壳式换热器的数学模型.与换热器设计软件HTRI的计算结果进行对比,结果表明该模型可以准确预测管壳式换热器的管壳侧出口温度.总传热系数敏感性计算表明,该参数随管壳侧流量变化而变化,在换热器性能预测时不能当作常数处理,应与工况进行耦合计算.当管壳侧体积流量小于1000 m3/h时,总传热系数对流量较为敏感;当体积流量大于1000m3/h时,流量的影响则相对较弱.该模型为预测换热器其他工况的换热性能提供基础,为换热设备调试提供指导,为核电厂设计验证及高效安全运行提供可靠依据.%Mathematical model is established for shell and tube heat exchanger of PWR residual heat removal system. Comparison with the calculated results from the design software HTRI for the heat exchanger is conducted, and the results show that outlet temperatures of shell and tube side are precisely predicted. The calculation of overall heat exchanger coefficient sensibility shows that this parameter varies with the flow rates of tube and shell side and it is not advisable to keep it as constant value in the simulation. The overall heat exchanger coefficient shall be coupled with the heat exchanger flow and heat exchanging conditions during calculation. The overall coefficient is extremely dependent on the flowrates which is less than 1000 m3/h while it seems to be independent with the higher flowrates. The model can be easily employed to predict other system conditions elsewhere and provide the convenient way for the plant test, design verification and high efficient operation of nuclear power plants.

  9. Preparation and characterization of zirconium (IV) molybdo tungsto vanado silicate as a novel inorganic ion exchanger in sorption of radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Zonoz, F. Mohammadi [Faculty of Chemistry, Damghan University of Basic Science, Damghan (Iran, Islamic Republic of); Ahmadi, S.J., E-mail: sjahmadi@aeoi.org.ir [Nuclear Science and Technology Research Institute, Nuclear Science Research School, P.O. Box 11365/8486, Tehran (Iran, Islamic Republic of); Nosrati, S. Attar [Faculty of Chemistry, Damghan University of Basic Science, Damghan (Iran, Islamic Republic of); Nuclear Science and Technology Research Institute, Nuclear Science Research School, P.O. Box 11365/8486, Tehran (Iran, Islamic Republic of); Maragheh, M. Ghannadi [Nuclear Science and Technology Research Institute, Nuclear Science Research School, P.O. Box 11365/8486, Tehran (Iran, Islamic Republic of)

    2009-09-30

    A new mixed metal heteropoly anion-based cation exchanger Zr(IV) molybdo tungsto vanado silicate (ZMTVS) was prepared under varying conditions. The material was characterized by FTIR, X-ray diffraction, TGA-DTA and SEM techniques. Its ion exchange capacity (IEC) for K{sup +} was found to be 0.86 meq g{sup -1}. Distribution coefficients (K{sub d}) values for 10 metal ions and three radioisotopes were determined. On the basis of K{sub d} values, two important and analytically difficult quantitative binary separations viz. Ni(II)-Co(II) and Ni(II)-Pb(II) were achieved on its column. Decontamination of aqueous nuclear waste solution was also studied.

  10. Molecular Simulation of Hydrogen Storage in Ion-Exchanged X Zeolites

    Directory of Open Access Journals (Sweden)

    Xiaoming Du

    2014-01-01

    Full Text Available Grand Canonical Monte Carlo (GCMC method was employed to simulate the adsorption properties of molecular hydrogen on ion-exchanged X zeolites at 100–293 K and pressures up to 10 MPa in this paper. The effect of cation type, temperature, and pressure on hydrogen adsorption capacity, heat of adsorption, adsorption sites, and adsorption potential energy of ion-exchanged X zeolites was analyzed. The results indicate that the hydrogen adsorption capacity increases with the decrease in temperatures and the increase in pressures and decreases in the order of KXcapacity. The hydrogen adsorption sites in the three zeolites were determined by the simulated distribution of hydrogen adsorption energy and the factors that influence their variations were discussed. Adsorption temperature has an important effect on the distribution of hydrogen molecules in zeolite pores.

  11. Natural zeolite reactivity towards ozone: the role of compensating cations.

    Science.gov (United States)

    Valdés, Héctor; Alejandro, Serguei; Zaror, Claudio A

    2012-08-15

    Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L(-1)). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH(3)-TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal.

  12. Thermodynamics of the first and second proton dissociations from aqueous L-aspartic acid and L-glutamic acid at temperatures from (278.15 to 393.15) K and at the pressure 0.35 MPa: Apparent molar heat capacities and apparent molar volumes of zwitterionic, protonated cationic, and deprotonated anionic forms at molalities from (0.002 to 1.0) mol . kg{sup -1}

    Energy Technology Data Exchange (ETDEWEB)

    Ziemer, S.P. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States); Woolley, E.M. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602-5700 (United States)]. E-mail: earl_woolley@byu.edu

    2007-04-15

    We have measured the densities of aqueous solutions of L-aspartic acid, L-glutamic acid, and equimolal solutions of these two amino acids with HCl and with NaOH at temperatures 278.15 {<=} T/K {<=} 368.15, at molalities 0.002 {<=} m/mol . kg{sup -1} {<=} 1.0 as solubity of the solutes allowed, and at p = 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15 {<=} T/K {<=} 393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes V {sub {phi}} and the heat capacities to calculate apparent molar heat capacities C {sub p,{phi}} for these solutions. We used our results and values from the literature for V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change {delta}{sub r} C {sub p,m}(T, m) for ionization of water to calculate parameters for {delta}{sub r} C {sub p,m}(T, m) for the first two proton dissociations from each of the protonated aqueous cationic amino acids. We used Young's Rule and integrated these results iteratively to account for the effects of equilibrium speciation and chemical relaxation on V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m). This procedure gave parameters for V {sub {phi}}(T, m) and C {sub p,{phi}}(T, m) for L-aspartinium and L-glutaminium chlorides and for monosodium L-aspartate and L-glutamate which modeled our observed results within experimental uncertainties. We report values for {delta}{sub r} C {sub p,m}, {delta}{sub r} H {sub m}, pQ {sub a}, {delta}{sub r} S {sub m}, and {delta}{sub r} V {sub m} for the first and second proton dissociations from protonated aqueous L-aspartic acid and L-glutamic acid as functions of T and m.

  13. Probing optical band gaps at nanoscale from tetrahedral cation vacancy defects and variation of cation ordering in NiCo2O4 epitaxial thin films

    Science.gov (United States)

    Dileep, K.; Loukya, B.; Silwal, P.; Gupta, A.; Datta, R.

    2014-10-01

    High resolution electron energy loss spectroscopy (HREELS) is utilized to probe the optical band gaps at the nanoscale in epitaxial NiCo2O4 (NCO) thin films with different structural order (cation/charge). The structure of NCO deviates from the ideal inverse spinel (non-magnetic and insulating) for films grown at higher temperatures (>500 °C) towards a mixed cation structure (magnetic with metallic conductivity) at lower deposition temperatures (<450 °C). This significantly modifies the electronic structure as well as the nature of the band gap of the material. Nanoscale regions with unoccupied tetrahedral A site cations are additionally observed in all the samples and direct measurement from such areas reveals considerably lower band gap values as compared to the ideal inverse spinel and mixed cation configurations. Experimental values of band gaps have been found to be in good agreement with the theoretical mBJLDA exchange potential based calculated band gaps for various cation ordering and consideration of A site cation vacancy defects. The origin of rich variation in cation ordering observed in this system is discussed.

  14. Measurement of antioxidant activity with trifluoperazine dihydrochloride radical cation

    Directory of Open Access Journals (Sweden)

    M.N. Asghar

    2008-06-01

    Full Text Available A novel, rapid and cost-effective trifluoperazine dihydrochloride (TFPH decolorization assay is described for the screening of antioxidant activity. A chromogenic reaction between TFPH and potassium persulfate at low pH produces an orange-red radical cation with maximum absorption at 502 nm in its first-order derivative spectrum. TFPH was dissolved in distilled water to give a 100 mM solution. The TFPH radical cation solution was made by reacting 0.5 mL of the solution with K2S2O8 (final concentration: 0.1 mM and diluting to 100 mL with 4 M H2SO4 solution. A linear inhibition of color production was observed with linearly increasing amounts of antioxidants, with correlation coefficients (R² ranging from 0.999 to 0.983. The antioxidant capacity of standard solutions of an antioxidant was evaluated by comparing with the inhibition curve using Trolox as the standard. Comparison of antioxidant capacity determined with this newly developed TFPH assay and with the well-known 2,2'-azinobis-[3-ethylbenzthiazoline-6-sulfonic acid] (ABTS-persulfate decolorization assay indicated the efficacy and sensitivity of the procedure. The proposed assay is less expensive (costs about US$4 per 100 assays and requires only 20 min for preparation of radical cation solution in comparison with ABTS assay, in which almost 12-16 h are required for preparation of a stable ABTS radical cation solution. The present assay has the advantage over ABTS assay that it can be used to measure the antioxidant activity of the samples, which are naturally found at a pH as low as 1, because the radical cation itself has been stabilized at low pH.

  15. Kafirin adsorption on ion-exchange resins: isotherm and kinetic studies.

    Science.gov (United States)

    Kumar, Prashant; Lau, Pei Wen; Kale, Sandeep; Johnson, Stuart; Pareek, Vishnu; Utikar, Ranjeet; Lali, Arvind

    2014-08-22

    Kafirin is a natural, hydrophobic and celiac safe prolamin protein obtained from sorghum seeds. Today kafirin is found to be useful in designing delayed delivery systems and coatings of pharmaceuticals and nutraceuticals where its purity is important and this can be obtained by adsorptive chromatography. This study is the first scientific insight into the isotherm and kinetic studies of kafirin adsorption on anion- and cation-exchange resins for practical applications in preparative scale chromatography. Adsorption isotherms of kafirin were determined for five anion- and two cation-exchange resins in batch systems. Isotherm parameters such as maximum binding capacity and dissociation constant were determined from Langmuir isotherm, and adsorptive capacity and affinity constant from Freundlich isotherm. Langmuir isotherm was found to fit the adsorption equilibrium data well. Batch uptake kinetics for kafirin adsorption on these resins was also carried out and critical parameters including the diffusion coefficient, film mass transfer coefficient, and Biot number for film-pore diffusion model were calculated. Both the isotherm and the kinetic parameters were considered for selection of appropriate resin for kafirin purification. UNOsphere Q (78.26 mg/ml) and Toyopearl SP-650M (57.4 mg/ml) were found to offer better kafirin binding capacities and interaction strength with excellent uptake kinetics under moderate operating conditions. With these adsorbents, film diffusion resistance was found to be major governing factor for adsorption (Bi<10 and δ<1). Based on designer objective function, UNOsphere Q was found be best adsorbent for binding of kafirin. The data presented is valuable for designing large scale preparative adsorptive chromatographic kafirin purification systems.

  16. Cationic Organic/Inorganic Hybrids and Their Swelling Properties

    Institute of Scientific and Technical Information of China (English)

    E. S. Dragan; L. Ghimici; M. Cazacu

    2005-01-01

    @@ 1Introduction Specific properties of poly(dimethylsiloxanes), such as low glass transition temperature, low surface energy, good insulating properties, biological and chemical inertness, high diffusion coefficient of gases, make them very attractive for practical applications in the daily life. However, there is a great interest last time in the preparation of ionic organic/inorganic materials with new properties for new applications. Quaternary ammonium salt(QAS) groups included in siloxane copolymers could induce new interesting properties such as:permanent fungicidal and bactericidal properties, which make them very attractive as materials for sanitary applications, improved selectivity coefficients of the gas-separation membranes, ion-exchange properties and so forth. So far, QAS groups have been located in the side chain[1,2]. Our interest was focused on the preparation of some novel cationic polysiloxane copolymers containing QAS groups of both integral type and pendent type[3,4]. Our objectives for the present study concern the synthesis of some cationic organic/siloxane hybrid materials with swelling properties controlled by both the nature of cationic organic component and the ratio between the organic and inorganic counterparts. Such cationic hybrid materials could be of interest for the preparation of new stimuli-responsive hydrogels[5,6].

  17. Electrically switched ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Lilga, M.A. [Pacific Northwest National Lab., Richland, WA (United States); Schwartz, D.T.; Genders, D.

    1997-10-01

    A variety of waste types containing radioactive {sup 137}Cs are found throughout the DOE complex. These waste types include water in reactor cooling basins, radioactive high-level waste (HLW) in underground storage tanks, and groundwater. Safety and regulatory requirements and economics require the removal of radiocesium before these wastes can be permanently disposed of. Electrically Switched Ion Exchange (ESIX) is an approach for radioactive cesium separation that combines IX and electrochemistry to provide a selective, reversible, and economic separation method that also produces little or no secondary waste. In the ESIX process, an electroactive IX film is deposited electrochemically onto a high-surface area electrode, and ion uptake and elution are controlled directly by modulating the potential of the film. For cesium, the electroactive films under investigation are ferrocyanides, which are well known to have high selectivities for cesium in concentrated sodium solutions. When a cathode potential is applied to the film, Fe{sup +3} is reduced to the Fe{sup +2} state, and a cation must be intercalated into the film to maintain charge neutrality (i.e., Cs{sup +} is loaded). Conversely, if an anodic potential is applied, a cation must be released from the film (i.e., Cs{sup +} is unloaded). Therefore, to load the film with cesium, the film is simply reduced; to unload cesium, the film is oxidized.

  18. Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations

    Directory of Open Access Journals (Sweden)

    María del Valle Martínez de Yuso

    2014-04-01

    Full Text Available Surface and bulk changes in a Nafion membrane as a result of IL-cation doping (1-butyl-3-methylimidazolium tetrafluoroborate or BMIM+BF4 and phenyltrimethylammonium chloride or TMPA+Cl− were studied by X-ray photoelectron spectroscopy (XPS, contact angle, differential scanning calorimetry (DSC and impedance spectroscopy (IS measurements performed with dry samples after 24 h in contact with the IL-cations BMIM+ and TMPA+. IL-cations were selected due to their similar molecular weight and molar volume but different shape, which could facilitate/obstruct the cation incorporation in the Nafion membrane structure by proton/cation exchange mechanism. The surface coverage of the Nafion membrane by the IL-cations was confirmed by XPS analysis and contact angle, while the results obtained by the other two techniques (DSC and IS seem to indicate differences in thermal and electrical behaviour depending on the doping-cation, being less resistive the Nafion/BMIM+ membrane. For that reason, determination of the ion transport number was obtained for this membrane by measuring the membrane or concentration potential with the samples in contact with HCl solutions at different concentrations. The comparison of these results with those obtained for the original Nafion membrane provides information on the effect of IL-cation BMIM+ on the transport of H+ across wet Nafion/BMIM+ doped membranes.

  19. Research progress in cation-π interactions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cation-π interaction is a potent intermolecular interaction between a cation and an aromatic system,which has been viewed as a new kind of binding force,as being compared with the classical interactions(e.g. hydrogen bonding,electrostatic and hydrophobic interactions). Cation-π interactions have been observed in a wide range of biological contexts. In this paper,we present an overview of the typical cation-π interactions in biological systems,the experimental and theoretical investigations on cation-π interactions,as well as the research results on cation-π interactions in our group.

  20. Research progress in cation-π interactions

    Institute of Scientific and Technical Information of China (English)

    CHENG JiaGao; LUO XiaoMin; YAN XiuHua; LI Zhong; TANG Yun; JIANG HuaLiang; ZHU WeiLiang

    2008-01-01

    Cation-π interaction is a potent intermolecular interaction between a cation and an aromatic system, which has been viewed as a new kind of binding force, as being compared with the classical interac-tions (e.g. hydrogen bonding, electrostatic and hydrophobic interactions). Cation-π interactions have been observed in a wide range of biological contexts. In this paper, we present an overview of the typi-cal cation-π interactions in biological systems, the experimental and theoretical investigations on cation-π interactions, as well as the research results on cation-π interactions in our group.

  1. Lack of association between a cationic protein and a cationic fluorosurfactant.

    Science.gov (United States)

    Macakova, Lubica; Nordstierna, Lars; Karlsson, Göran; Blomberg, Eva; Furó, István

    2007-01-16

    Surface tension, 19F and 1H NMR spectroscopy, and cryotransmission electron microscopy are used to characterize the state of association in aqueous solutions of a fluorosurfactant CF3(CF2)nSO2NH(CH2)3-4N(CH3)3+ I- (n = 8, 6) with and without lysozyme added. In the absence of lysozyme, we find monomers, small aggregates, and large vesicles to coexist, with the individual fluorosurfactant molecules exchanging slowly (>1 ms) among those states. When both lysozyme and fluorosurfactant are present in the solution, they have no measurable influence on the physical state of the other. In contrast, a hydrogenated cationic surfactant with the same headgroup, hexadecyltrimethylammonium bromide, is shown to associate to lysozyme.

  2. The Effects of Sulfonated Poly(ether ether ketone Ion Exchange Preparation Conditions on Membrane Properties

    Directory of Open Access Journals (Sweden)

    Rebecca S. L. Yee

    2013-08-01

    Full Text Available A low cost cation exchange membrane to be used in a specific bioelectrochemical system has been developed using poly(ether ether ketone (PEEK. This material is presented as an alternative to current commercial ion exchange membranes that have been primarily designed for fuel cell applications. To increase the hydrophilicity and ion transport of the PEEK material, charged groups are introduced through sulfonation. The effect of sulfonation and casting conditions on membrane performance has been systematically determined by producing a series of membranes synthesized over an array of reaction and casting conditions. Optimal reaction and casting conditions for producing SPEEK ion exchange membranes with appropriate performance characteristics have been established by this uniquely systematic experimental series. Membrane materials were characterized by ion exchange capacity, water uptake, swelling, potential difference and NMR analysis. Testing this extensive membranes series established that the most appropriate sulfonation conditions were 60 °C for 6 h. For mechanical stability and ease of handling, SPEEK membranes cast from solvent casting concentrations of 15%–25% with a resulting thickness of 30–50 µm were also found to be most suitable from the series of tested casting conditions. Drying conditions did not have any apparent impact on the measured parameters in this study. The conductivity of SPEEK membranes was found to be in the range of 10−3 S cm−1, which is suitable for use as a low cost membrane in the intended bioelectrochemical systems.

  3. Heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Craig, L.B.; Farma, A.J.

    1987-01-06

    This invention concerns a heat exchanger as used in a space heater, of the type in which hot exhaust gases transfer heat to water or the like flowing through a helical heat exchange coil. A significant improvement to the efficiency of the heat exchange occurring between the air and water is achieved by using a conduit for the water having external helical fluting such that the hot gases circulate along two paths, rather than only one. A preferred embodiment of such a heat exchanger includes a porous combustion element for producing radiant heat from a combustible gas, surrounded by a helical coil for effectively transferring the heat in the exhaust gas, flowing radially from the combustion element, to the water flowing through the coil. 4 figs.

  4. Contribution des argiles et des matières organiques à la rétention de l'eau dans les sols. Signification et rôle fondamental de la capacité d'échange en cations

    Science.gov (United States)

    Bigorre, François; Tessier, Daniel; Pédro, Georges

    2000-02-01

    Water retention properties of soils and clays extracted from soil profile horizons were analyzed as a function of their cation exchange capacity (CEC) and EGME surface area. The water retention at -1.6 MPa matric potential correlated well with the CEC. At this water potential, organic matter and clay have their own and additive water retention properties. At -107 MPa, clays still retained adsorbed water, whereas organic matter was completely dehydrated. Consequently, the EGME surface area and water adsorption isotherms at -107 MPa provide information on clay surface properties, while those of organic matter are not assessed by the methods.

  5. Finned Small Diameter Tube Heat Exchanger

    Science.gov (United States)

    Dang, Chaobin; Daiguji, Hirofumi; Hihara, Eiji; Tokunaga, Masahide

    The performance of fined small tube heat exchangers was investigated both experimentally and theoretically. The Inner diameters of tubes were 1.0mm, 2.1mm and 4.0mm. Exchanged heat and pressure drop obtained from numerical simulation agreed well with the experimental ones. Calculation results show that the volume of a 2.0mm tube heat exchanger can be reduced to 33% of that of a 4mm tube heat exchanger with the same capacity. In addition the distribution of two-phase flow in a branching unit was investigated by measuring downstream temperature distribution. The flow distribution in a branching unit strongly affects the exchanged heat.

  6. 弱阳离子交换纳米磁珠介导的帕金森病血清蛋白质组学的初步研究%Proteomic study for serum biomarkers in Parkinson's disease using weak cation exchange magnetic beads and MALDI-TOF-MS

    Institute of Scientific and Technical Information of China (English)

    王坚; 李尧华; 郑晓立; 张燕莉; 李昕; 于顺; 何欣; 陈彪

    2009-01-01

    Objective To screen for the potential protein biomarkers in serum for the diagnosis of idiopathic Parkinson's disease (PD) using proteomic fingerprint technology. Methods Proteomic fingerprint technology combining weak cation exchange (WCX) magnetic beads with MALDI-TOF-MS was used to identify and compare the serum proteins from 61 patients with idiopathic PD, 29 patients with other neurodegenerative diseases (OND) and 30 healthy blood donors. Model of biomarkers and proteomics patterns associated with PD was analyzed by Biomarker Patterns Software. The model also was validated by 40 newly recruited PD cases. Results A total of 17 discriminating M/Z peaks which were related to PD were identified ( nonparametric test, Z:-4.039--2.633, P<0.01 ). Five biomarkers with M/Z of 6121, 5234, 2961,4309 and 8170 respectively generated an excellent model of distinguishing between PD and healthy groups. The sensitivity was 98.4% and the specificity was 83.1%. Blind testing in 40 newly recruited cases demonstrated a sensitivity of 85.0% (17 of 20 PD) and a specificity of 70. 0% (14 of 20 controls). Conclusions Combination of WCX magnetic beads with MALDI-TOF-MS is a useful method in establishing proteomic patterns associated with PD. It also may be used to construct a diagnostic model with PD Biomarkers. Although this model of biomarkers fails to distinguish between PD and OND controls, it is able to differentiate PD from healthy controls.%目的 探讨帕金森病(PD)患者血清蛋白质组学特征,筛选PD特征性生物标志物.方法 选择原发性PD患者61例、其他神经变性病(OND)患者29例和健康人30名,用弱阳离子交换(WCX)纳米磁珠捕获血清蛋白质组分,用MALDI-TOF-MS(matrix assisted laser desorption/ionization time of flight inass spectrometer)检测各样品的蛋白质质谱,用Biomarker Wizard 3.1和Biomarker Patterns Software Version 5.0软件进行数据分析,筛选差异分子并建立PD诊断模型.用盲法验证此模型.结果

  7. Preparation of strong cation-exchange monolithic column and its application in polypeptide separation by capillary electrochromatography%强阳离子交换整体柱的研制及其在电色谱多肽分离中的应用

    Institute of Scientific and Technical Information of China (English)

    齐楠; 崔瑞红; 尤慧艳

    2011-01-01

    以丙烯酸、2-丙烯酰胺-2-甲基丙磺酸为功能单体,N,N'-亚甲基双丙烯酰胺为交联剂,正十二醇、1,4-丁二醇及二甲基亚砜为致孔剂,偶氮二异丁腈为引发剂,原位聚合制备了丙烯酰胺类强阳离子交换整体柱.考察了驱动电压、有机调节剂、盐浓度、pH值等对电渗流的影响.结果表明,电渗流与驱动电压的线性关系良好,相关系数为0.998 1;有机调节剂乙腈对电渗流的影响除与流动相的黏度有关外,还与同定相的溶胀有关,当浓度低时,电渗流随乙腈浓度的增加有反常的下降趋势;随着磷酸盐浓度逐渐增加,电渗流降低,与理论相符;在pH值为3~9范围内,电渗流基本上保持恒定,体现了整体柱使用酸碱范围宽的优越性.在优化的实验条件下,采用毛细管电色谱法在此整体柱上成功分离了5种多肽,体现了该类整体柱在多肽分离研究中的优势,为进一步将其应用于蛋白质分离研究打下了基础.%A strong cation-exchange monolithic column was prepared by polymerization inside the fused-silica capillary. The solution consisted of acrylic acid and 2-acrylamido-2-methyl-l-propanesulfonic acid as functional monomers, 7V,AT'-methyIenebisacrylamide as a cross-linking agent, dimethyl sulphoxide and dodecanol, 1,4-butanediol as organic porogenic solvents and azobisisobutyronitrile as a suitable initiator. The effects of the applied voltage, concentrations of organic modifier and salt solution, pH value on the electroosmotic flow were investigated. The experimental results showed that there existed a good linear relationship between the applied voltage and electroosmotic flow with a correlation coefficient of 0. 998 1 ; When the concentration of organic modifier (acetonitrile, CAN) was less than 70% , the swelling degree of stationary phase played a main role and the electroosmotic flow was decreased abnormally with the increase of CAN concentration; The electroosmotic flow

  8. Heavy metal cations permeate the TRPV6 epithelial cation channel.

    Science.gov (United States)

    Kovacs, Gergely; Danko, Tamas; Bergeron, Marc J; Balazs, Bernadett; Suzuki, Yoshiro; Zsembery, Akos; Hediger, Matthias A

    2011-01-01

    TRPV6 belongs to the vanilloid family of the transient receptor potential channel (TRP) superfamily. This calcium-selective channel is highly expressed in the duodenum and the placenta, being responsible for calcium absorption in the body and fetus. Previous observations have suggested that TRPV6 is not only permeable to calcium but also to other divalent cations in epithelial tissues. In this study, we tested whether TRPV6 is indeed also permeable to cations such as zinc and cadmium. We found that the basal intracellular calcium concentration was higher in HEK293 cells transfected with hTRPV6 than in non-transfected cells, and that this difference almost disappeared in nominally calcium-free solution. Live cell imaging experiments with Fura-2 and NewPort Green DCF showed that overexpression of human TRPV6 increased the permeability for Ca(2+), Ba(2+), Sr(2+), Mn(2+), Zn(2+), Cd(2+), and interestingly also for La(3+) and Gd(3+). These results were confirmed using the patch clamp technique. (45)Ca uptake experiments showed that cadmium, lanthanum and gadolinium were also highly efficient inhibitors of TRPV6-mediated calcium influx at higher micromolar concentrations. Our results suggest that TRPV6 is not only involved in calcium transport but also in the transport of other divalent cations, including heavy metal ions, which may have toxicological implications.

  9. Natural zeolite reactivity towards ozone: The role of compensating cations

    Energy Technology Data Exchange (ETDEWEB)

    Valdes, Hector, E-mail: hvaldes@ucsc.cl [Laboratorio de Tecnologias Limpias (F. Ingenieria), Universidad Catolica de la Santisima Concepcion, Alonso de Ribera 2850, Concepcion (Chile); Alejandro, Serguei; Zaror, Claudio A. [Departamento de Ingenieria Quimica (F. Ingenieria), Universidad de Concepcion, Concepcion (Chile)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Chemical and thermal treatment enhances catalytic activity of natural zeolite. Black-Right-Pointing-Pointer Modified natural zeolite exhibits high stability after thermal treatment. Black-Right-Pointing-Pointer Reducing the compensating cation content leads to an increase on ozone abatement. Black-Right-Pointing-Pointer Surface active atomic oxygen was detected using the DRIFT technique. Black-Right-Pointing-Pointer The highest reactivity toward ozone was performed by NH4Z3 zeolite sample. - Abstract: Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L{sup -1}). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77 K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH{sub 3}-TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal.

  10. The adjuvant mechanism of cationic dimethyldioctadecylammonium liposomes

    DEFF Research Database (Denmark)

    Korsholm, Karen Smith; Agger, Else Marie; Foged, Camilla;

    2007-01-01

    Cationic liposomes are being used increasingly as efficient adjuvants for subunit vaccines but their precise mechanism of action is still unknown. Here, we investigated the adjuvant mechanism of cationic liposomes based on the synthetic amphiphile dimethyldioctadecylammonium (DDA). The liposomes ...

  11. Tripodal Receptors for Cation and Anion Sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman,; Verboom, Willem; Reinhoudt, David N.

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing

  12. Ion exchange properties of humus acids

    Science.gov (United States)

    Shoba, V. N.; Chudnenko, K. V.

    2014-08-01

    Ion exchange equilibriums in a complex of brown humic acids (HAs) and related fulvic acids (FAs) with cations (H+, K+, Na+, Ca2+, Mg2+, Zn2+, Mn2+, Cu2+, Fe3+, and Al3+) have been studied, and the activity coefficients of the acid monoionic forms have been determined. The composition of the stoichiometric cell in the system of black and brown HAs and related FAs in a leached chernozem of the Ob' region has been calculated with consideration for the earlier studies of the ion exchange properties of black HAs and related FAs. It has been shown that hydrogen, calcium, magnesium, aluminum, and iron are the major components in the exchange complex of humus acids in the leached chernozem with the other cations being of subordinate importance. In spite of some differences between the analytical and calculated compositions of the humus acids, the results of the calculations can be considered satisfactory. They indicate that calculations are feasible for such complex objects as soils, and their accuracy will improve with the expansion of the experimental studies. The physicochemical simulation of the transformation of the humus acid composition under different acid-base conditions shows that the contents of most cations decrease under alkalization, and hydroxides or carbonates become the most stable forms of these cations. Under the acidification of solutions, the binding of alkaline and alkaline-earth elements by humus acids decreases and the adsorption of iron and aluminum by humus acids increases.

  13. Enhanced Mixed Electronic-Ionic Conductors through Cation Ordering

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Allan J. [Univ. of Houston, TX (United States); Morgan, Dane [Univ. of Wisconsin, Madison, WI (United States); Grey, Clare [Stony Brook Univ., NY (United States)

    2014-08-31

    The performance of many energy conversion and storage devices depend on the properties of mixed ionic-electronic conducting (miec) materials. Mixed or ambipolar conductors simultaneously transport ions and electrons and provide the critical interface between chemical and electrical energy in devices such as fuel cells, ion transport membranes, and batteries. Enhancements in storage capacity, reversibility, power density and device lifetime all require new materials and a better understanding of the fundamentals of ambipolar conductivity and surface reactivity.The high temperature properties of the ordered perovksites AA’B2O5+x, where A = rare earth ion, Y and B = Ba, Sr were studied. The work was motivated by the high oxygen transport and surface exchange rates observed for members of this class of mixed ionic and electronic conductors. A combined experimental and computational approach, including structural, electrochemical, and transport characterization and modeling was used. The approach attacks the problem simultaneously at global (e.g., neutron diffraction and impedance spectroscopy), local (e.g., pair distribution function, nuclear magnetic resonance) and molecular (ab initio thermokinetic modeling) length scales. The objectives of the work were to understand how the cation and associated anion order lead to exceptional ionic and electronic transport properties and surface reactivity in AA’B2O5+x perovskites. A variety of compounds were studied by X-ray and neutron diffraction, measurements of thermodynamics and transport and theoretically. These included PrBaCo2O5+x and NdBaCo2O5+x, PrBaCo2-xFexO6- δ (x = 0, 0.5, 1.0, 1.5 and 2) and LnBaCoFeO6- δ (Ln = La, Pr, Nd, Sm, Eu and Gd), Sr3YCo4O10.5, YBaMn2O5+x. A0.5A’0.5BO3 (where A=Y, Sc, La, Ce, Pr, Nd, Pm, Sm; A’= Sr

  14. Characterization and adsorption properties of a lanthanum-loaded magnetic cationic hydrogel composite for fluoride removal.

    Science.gov (United States)

    Dong, Shuoxun; Wang, Yili

    2016-01-01

    In this study, a novel lanthanum-loaded magnetic cationic hydrogel (MCH-La) was synthesized for fluoride adsorption from drinking water. The adsorption kinetics, isotherms, and effects of pH and co-existing anions on fluoride uptake by MCH-La were evaluated. FTIR, Raman and XPS were used to analyze the fluoride adsorption mechanism of MCH-La. Results showed that MCH-La had positive zeta potential values of 23.6-8.0 mV at pH 3.0-11.0, with the magnitude of saturation magnetization up to 10.3 emu/g. The fluoride adsorption kinetics by MCH-La fitted well with the fractal-like-pseudo-second-order model, and the adsorption capacity reached 93% of the ultimate adsorption capacity within the first 10 min. The maximum fluoride adsorption capacity for MCH-La was 136.78 mg F(-)/g at an equilibrium fluoride concentration of 29.3 mg/L and pH 7.0. Equilibrium adsorption data showed that the Sips model was more suitable than the Langmuir and Freundlich models. MCH-La still had more than 100 mg of F(-)/g adsorption capacity at a strongly alkaline solution (pH > 10). The adsorption process was highly pH-dependent, and the optimal adsorption was attained at pH 2.8-4.0, corresponding to ligand exchange, electrostatic interactions, and Lewis acid-base interactions. With the exception of both anions of HCO3(-) and SiO4(4-), Cl(-), NO3(-), and SO4(2-) did not evidently prevent fluoride removal by MCH-La at their real concentrations in natural groundwater. The fluoride adsorption capacity of the regenerated MCH-La approached 70% of the fresh MCH-La from the second to fifth recycles. FTIR and Raman spectra revealed that C-O and CO functional groups on MCH contributed to the fluoride adsorption, this finding was also confirmed by the XPS F 1s spectra. Deconvolution of C 1s spectra before and after fluoride adsorption indicated that the carboxyl, anhydride, and phenol groups of MCH were involved in the fluoride removal.

  15. Exchangers man the pumps: Functional interplay between proton pumps and proton-coupled Ca(2+) exchangers

    Science.gov (United States)

    Tonoplast-localised proton-coupled Ca(2+) transporters encoded by cation/H(+) exchanger (CAX) genes play a critical role in sequestering Ca(2+) into the vacuole. These transporters may function in coordination with Ca(2+) release channels, to shape stimulus-induced cytosolic Ca(2+) elevations. Recen...

  16. Microscopic approach for the identification of cationic membrane fouling during cheddar cheese whey electroacidification.

    Science.gov (United States)

    Lin Teng Shee, F; Angers, P; Bazinet, L

    2008-06-15

    This is the first time that fouling of cation-exchange membranes during cheddar cheese whey electroacidification with bipolar membranes is reported. A mineral fouling was observed only on the cationic membrane side in contact with the base. The deposit was identified as magnesium hydroxide and this fouling was more important on the cation-exchange membrane situated close to the cathode. Little deposit was formed after six electroacidification runs, but on long time, the buildup of fouling film would lead after many electroacidifications to an important decrease of the system efficiency. Since, fouling of permselective membranes represents one of the major issues in electrodialytic processes, this result will be the basis for the determination of cleaning conditions allowing the prevention of such a fouling.

  17. Incorporation of Monovalent Cations in Sulfate Green Rust

    DEFF Research Database (Denmark)

    Christiansen, B. C.; Dideriksen, K.; Katz, A.;

    2014-01-01

    Green rust is a naturally occurring layered mixed-valent ferrous-ferric hydroxide, which can react with a range of redox-active compounds. Sulfate-bearing green rust is generally thought to have interlayers composed of sulfate and water. Here, we provide evidence that the interlayers also contain...... with water showed that Na+ and K+ were structurally fixed in the interlayer, whereas Rb+ and Cs+ could be removed, resulting in a decrease in the basal layer spacing. The incorporation of cations in the interlayer opens up new possibilities for the use of sulfate green rust for exchange reactions with both...

  18. Single-stage separation and esterification of cation salt carboxylates using electrodeionization

    Science.gov (United States)

    Lin, YuPo J.; Henry, Michael; Hestekin, Jamie; Snyder, Seth W.; St. Martin, Edward J.

    2006-11-28

    A method of and apparatus for continuously making an organic ester from a lower alcohol and an organic acid is disclosed. An organic acid or salt is introduced or produced in an electrode ionization (EDI) stack with a plurality of reaction chambers each formed from a porous solid ion exchange resin wafer interleaved between anion exchange membranes or an anion exchange membrane and a cation exchange membrane or an anion exchange membrane and a bipolar exchange membranes. At least some reaction chambers are esterification chambers and/or bioreactor chambers and/or chambers containing an organic acid or salt. A lower alcohol in the esterification chamber reacts with an anion to form an organic ester and water with at least some of the water splitting with the ions leaving the chamber to drive the reaction.

  19. Preparation and Photochemical Behavior of a Cationic Azobenzene Dye-Montmorillonite Intercalation Compound

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Montmorillonite/cationic azobenzene dye(p-(δ-triethylammoniobutoxy)-p'-methyl-azobenzene bromide) intercalation compounds were prepared by the conventional ion exchange method. As compared with that of pure cationic azo-dye, the thermal stability of the intercalated dye was greatly enhanced, and the absorption band corresponding to azobenzene group in intercalated dye shifted towards longer wave length by 38 nm. This could be ascribed to the strong conjugation of cationic azo-dye supramolecular order structure(J cluster) confined in a nanoscale space of montmorillonite interlayer gallery. UV/vis spectra data show that the intercalated azo dye in the montmorillonite interlayer space exhibited reversible trans-to-cis photoisomerization and daylight cis-to-trans back reaction. FTIR indicates the successful intercalation of cationic azo-dye into the montmorillonite interlayer.

  20. Enthalpy-entropy compensation for n-hexane adsorption on Y zeolite containing transition metal cations

    Directory of Open Access Journals (Sweden)

    Hercigonja R.

    2015-01-01

    Full Text Available In this work, the values of entropy changes related to n-hexane adsorption onto cation exchanged Y zeolite were calculated from differential heats. Various transition metal cations (Co2+, Ni2+, Zn2+ and Cd2+ were introduced into the lattice of the parent NaY, and the existence of enthalpy-entropy compensation effect related to n-hexane adsorption, id. est, the linearity of -ΔH vs. -ΔS plots was examined. The compensation effect was confirmed for all investigated zeolites. The compensation effect can be comprehended as governed by ion-induced dipole interaction between highly polarizing cationic centers in zeolite and nonopolar n-hexane molecules. Finally, the compensation effect and so the compensation temperature were found to depend on the type of charge-balancing cation (charge, size and electronic configuration. [Projekat Ministarstva nauke Republike Srbije, br. 172018

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

    Science.gov (United States)

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

    2008-10-23

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

  2. Desalination of Saline Sludges Using Ion-Exchange Column with Zeolite

    Directory of Open Access Journals (Sweden)

    Abdel E. Ghaly

    2008-01-01

    Full Text Available A flushing process followed by a zeolite based ion-exchange process were developed for the treatment of saline sludges from oil and gas exploration sites. The particle size distribution of sludge sample indicated the presence of very fine sand and clay. The electrical conductivity of the sludge was 42.2 dS m-1 indicating very saline sludge and the Cation Exchange Capacity (CEC was 40 cmoL kg-1 which was very suitable for ion-exchange process. A 500 g sample of saline sludge (containing CaCl2:MgCl2:NaCl ratio as 1:1.16:36.61 was washed using demineralized water in a mixed reactor and the sludge was allowed to settle for 36 h. The optimal number of washes was determined to be two washes with an overall salt removal efficiency of 94.47%. The treated sludge contained 515 mg salt kg-1 sludge (or 0.05% w w-1 and was suitable for agricultural application. The washwater was passed through a Mountain Stronach zeolite (chabazite based ion-exchange column for salt reduction. The sodium salt removal efficiency was 75.34%. This was increased to 99.79% when using two ion-exchange columns. The Ca and Mg ions were under regulatory limits and required no further treatment. The final salt concentration in the wash water was 314.0 mg L-1 which was below the limits established by the Canadian Guidelines. For complete removal of total salts, a series of ion-exchange columns with different zeolites (for removal of NaCl, MgCl2 and CaCl2 will be required.

  3. International Exchanges

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>On April 1st,2014,CPAPD Deputy Secretary General Ms.Chen Huaifan met with Mr.Djudjuk Juyoto Suntani,President of the World Peace Committee,Indonesia,who headed the delegation,in the CPAPD office.The two sides exchanged views on issues of common concern including cooperation between the two organizations and the inheritance of Chinese culture.

  4. Exchange Options

    NARCIS (Netherlands)

    Jamshidian, Farshid

    2007-01-01

    The contract is described and market examples given. Essential theoretical developments are introduced and cited chronologically. The principles and techniques of hedging and unique pricing are illustrated for the two simplest nontrivial examples: the classical Black-Scholes/Merton/Margrabe exchange

  5. Ion Exchange Technology Development in Support of the Urine Processor Assembly Precipitation Prevention Project for the International Space Station

    Science.gov (United States)

    Mitchell, Julie L.; Broyan, James L.; Pickering, Karen D.; Adam, Niklas; Casteel, Michael; Callahan, Michael; Carrier, Chris

    2012-01-01

    In support of the Urine Processor Assembly Precipitation Prevention Project (UPA PPP), multiple technologies were explored to prevent CaSO4 2H2O (gypsum) precipitation during the on-orbit distillation process. Gypsum precipitation currently limits the water recovery rate onboard the International Space Station (ISS) to 70% versus the planned 85% target water recovery rate. Due to its ability to remove calcium cations in pretreated augmented urine (PTAU), ion exchange was selected as one of the technologies for further development by the PPP team. A total of 13 ion exchange resins were evaluated in various equilibrium and dynamic column tests with solutions of dissolved gypsum, urine ersatz, PTAU, and PTAU brine at 85% water recovery. While initial evaluations indicated that the Purolite SST60 resin had the highest calcium capacity in PTAU (0.30 meq/mL average), later tests showed that the Dowex G26 and Amberlite FPC12H resins had the highest capacity (0.5 meq/mL average). Testing at the Marshall Spaceflight Center (MSFC) integrates the ion exchange technology with a UPA ground article under flight-like pulsed flow conditions with PTAU. To date, no gypsum precipitation has taken place in any of the initial evaluations.

  6. Effects of ionic speciation of lysine on its adsorption and desorption through a sulfone-type ion-exchange column.

    Science.gov (United States)

    Choi, Dong-Hyouk; Lee, Kisay

    2007-09-01

    Lysine produced during microbial fermentation is usually recovered by an ion-exchange process, in which lysine is first converted to the cationic form (by lowering the pH to less than 2.0 with sulfuric acid) and then fed to a cation-exchange column containing an exchanger that has a sulfone group with a weak counterion such as NH4+. Ammonia water with a pH above 11 is then supplied to the column to displace the purified lysine from the column and allow its recovery. To enhance the adsorption capacity and for a possible reduction in chemical consumption, monovalent lysine fed at pH 4 was investigated in comparison with conventional divalent lysine fed at pH 1.5. The adsorption capacity increased by more than 70% on a mass basis using pH 4 feeding compared with pH 1.5 feeding. Lysine adsorbed at pH 4 started to elute earlier than that adsorbed at pH 1.5 when ammonia water was used as the eluant solution, and the extent of early elution became more notable at lower concentrations of ammonia. Moreover, the elution of monovalent lysine fed at pH 4 displayed a stiffer front boundary and higher peak concentration. However, when the ammonium concentration was greater than 2.0 N, complete saturation of the bed was delayed during adsorption and the percent recovery yield from elution was lowered, both drawbacks that were considered inevitable features originating from the increased adsorption of monovalent lysine.

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

    Science.gov (United States)

    Li, Li; Jia, Hanzhong; Li, Xiyou; Wang, Chuanyi

    2015-01-01

    In this study, anthracene was employed as a probe to explore the potential catalytic effect of clay minerals in soil environment. Clay minerals saturated with various exchangeable cations were tested. The rate of anthracene transformation follows the order: Fe-smectite > Cu-smectite > Al-smectite ≈ Ca-smectite ≈ Mg-smectite ≈ Na-smectite. This suggests that transition-metal ions such as Fe(III) play an important role in anthracene transformation. Among Fe(III)-saturated clays, Fe(III)-smectite exhibits the highest catalytic activity followed by Fe(III)-illite, Fe(III)-pyrophyllite, and Fe(III)-kaolinite, which is in agreement with the interlayer Fe(III) content. Moreover, effects by two common environmental factors, pH and relative humidity (RH), were evaluated. With an increase in pH or RH, the rate of anthracene transformation decreases rapidly at first and then is leveled off. GC-MS analysis identifies that the final product of anthracene transformation is 9,10-anthraquinone, a more bioavailable molecule compared to anthracene. The transformation process mainly involves cation-π bonding, electron transfer leading to cation radical, and further oxidation by chemisorbed O2. The present work provides valuable insights into the abiotic transformation and the fate of PAHs in the soil environment and the development of contaminated land remediation technologies.

  8. The Free Tricoordinated Silyl Cation Problem

    Directory of Open Access Journals (Sweden)

    Čičak, H.

    2010-03-01

    Full Text Available As the importance and abundance of silicon in our environment is large, it has been thought that silicon might take the place of carbon in forming a host of similar compounds and silicon-based life. However, until today there is no experimental evidence for such a hypothesis and carbon is still unique among the elements in the vast number and variety of compounds it can form. Also, the corresponding derivatives of the two elements show considerable differences in their chemical properties.The essential debate concerning organosilicon chemistry relates to the existence of the free planar tricoordinated silyl cations in condensed phase (R3Si+, in analogy to carbocations (R3C+ which have been known and characterized as free species. Although silyl cations are thermodynamically more stable than their carbon analogs, they are very reactive due to their high inherent electrophilicity and the ability of hypervalent coordination. On the other hand, stabilization by inductive and hyperconjugative effects and larger steric effects of carbocations make them less sensitive to solvation or other environmental effects than silyl cations. Hence, observation of free silyl cations in the condensed phase proved extremely difficult and the actual problem is the question of the degree of the (remaining silyl cation character.The first free silyl cation, trimesitylsilyl cation, and in analogy with it tridurylsilyl cation, were synthesized by Lambert et al. Free silyl cations based on analogy to aromatic ions (homocyclopropenylium and tropylium have also been prepared. However, in these silyl cations the cationic character is reduced by internal π -conjugation. Čičak et al. prepared some silyl-cationic intermediates (Me3Si--CH≡CR+in solid state. With the help of quantum-mechanical calculations it was concluded that these adducts have much more silyl cation than carbocation character.

  9. Antimicrobial properties of zeolite-X and zeolite-A ion-exchanged with silver, copper, and zinc against a broad range of microorganisms.

    Science.gov (United States)

    Demirci, Selami; Ustaoğlu, Zeynep; Yılmazer, Gonca Altın; Sahin, Fikrettin; Baç, Nurcan

    2014-02-01

    Zeolites are nanoporous alumina silicates composed of silicon, aluminum, and oxygen in a framework with cations, water within pores. Their cation contents can be exchanged with monovalent or divalent ions. In the present study, the antimicrobial (antibacterial, anticandidal, and antifungal) properties of zeolite type X and A, with different Al/Si ratio, ion exchanged with Ag(+), Zn(2+), and Cu(2+) ions were investigated individually. The study presents the synthesis and manufacture of four different zeolite types characterized by scanning electron microscopy and X-ray diffraction. The ion loading capacity of the zeolites was examined and compared with the antimicrobial characteristics against a broad range of microorganisms including bacteria, yeast, and mold. It was observed that Ag(+) ion-loaded zeolites exhibited more antibacterial activity with respect to other metal ion-embedded zeolite samples. The results clearly support that various synthetic zeolites can be ion exchanged with Ag(+), Zn(2+), and Cu(2+) ions to acquire antimicrobial properties or ion-releasing characteristics to provide prolonged or stronger activity. The current study suggested that zeolite formulations could be combined with various materials used in manufacturing medical devices, surfaces, textiles, or household items where antimicrobial properties are required.

  10. Amine-functionalized, silver-exchanged zeolite NaY: Preparation, characterization and antibacterial activity

    Science.gov (United States)

    Hanim, Siti Aishah Mohd; Malek, Nik Ahmad Nizam Nik; Ibrahim, Zaharah

    2016-01-01

    Amine-functionalized, silver-exchanged zeolite NaY (ZSA) were prepared with three different concentrations of 3-aminopropyltriethoxysilane (APTES) (0.01, 0.20 and 0.40 M) and four different concentrations of silver ions (25%, 50%, 100% and 200% from zeolite cation exchange capacity (CEC)). The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), surface area analysis, thermogravimetric analysis (TGA) and zeta potential (ZP) analysis. The FTIR results indicated that the zeolite was functionalized by APTES and that the intensity of the peaks corresponding to APTES increased as the concentration of APTES used was increased. The antibacterial activities of the silver-exchanged zeolite NaY (ZS) and ZSA were studied against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538 using the disc diffusion technique (DDT) and minimum inhibitory concentration (MIC). The antibacterial activity of ZSA increased with the increase in APTES on ZS, and E. coli was more susceptible towards the sample compared to S. aureus. The FESEM micrographs of the bacteria after contact with the ZSA suggested different mechanisms of bacterial death for these two bacteria due to exposure to the studied sample. The functionalization of ZS with APTES improved the antibacterial activity of the silver-zeolite, depending on the concentration of silver ions and APTES used during modification.

  11. Characterization of magnetic ion-exchange composites for protein separation from biosuspensions.

    Science.gov (United States)

    Käppler, Tobias E; Hickstein, Birgit; Peuker, Urs A; Posten, Clemens

    2008-06-01

    Downstream processing is a major issue in biotechnological production. A multitude of unit operations with nonsatisfying yield are often used to reach the desired product purity. Direct recovery technologies such as high-gradient magnetic fishing (HGMF) are advantageous because of their ability to separate the desired product in early stages from crude cultivation broths. However, the use of magnetic particles to capture valuable biotechnological products is often linked to the drawback that support particles are expensive and not available in greater quantities. This current work presents new composite magnetic particles that can be used in biotechnology. They are manufactured by a spray drying process. During this process, the nanosized magnetite particles as well as functional ion-exchange nanoparticles are integrated into one particle in which they are linked by a matrix polymer. The production procedure is flexible, scalable, and therefore economical. These particles have good adsorption capacities of up to 85 mg/g adsorbed protein and good binding kinetics. They are resistant to harsh conditions such as short ultrasonic treatment or extreme pHs. In order to test their usefulness in biosuspensions, model proteins were separated using these particles. The anion and cation exchanger particles separated lysozyme (LZ) or BSA from cultivation suspensions. The selectivity of recovery was dependent on other proteins present as is usual for ion-exchange binding mechanisms.

  12. Selective ion exchange recovery of rare earth elements from uranium mining solutions

    Science.gov (United States)

    Rychkov, Vladimir N.; Kirillov, Evgeny V.; Kirillov, Sergey V.; Bunkov, Grigory M.; Mashkovtsev, Maxim A.; Botalov, Maxim S.; Semenishchev, Vladimir S.; Volkovich, Vladimir A.

    2016-09-01

    A comparative study of rare earth, ferric and aluminum ions ion exchange behavior on gel sulfonated p;olystyrene cation exchange resins depending on the degree of the matrix cross-linking and pH of the solution is presented. Selective ion exchange of REEs is possible at the pH range of 1.5-2.0 using strongly acidic cation exchange resins containing more than 8 % of DVB. The preliminary results of testing the efficiency of REEs recovery from the industrial uranium underground leaching solutions are also presented.

  13. Anion exchange selectivity of surfactant modified clinoptilolite-rich tuff for environmental remediation.

    Science.gov (United States)

    de Gennaro, Bruno; Catalanotti, Lilia; Bowman, Robert S; Mercurio, Mariano

    2014-09-15

    describe cation exchange selectivity in zeolites. Finally, it was also verified that the zeolite modified with HDTMA-Cl is able to better exploit its anion exchange capacity compared to the same zeolite modified with HDTMA-Br.

  14. Cd/Hg cationic substitution in magic-sized CdSe clusters: Optical characterization and theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Antanovich, Artsiom; Prudnikau, Anatol; Gurin, Valerij; Artemyev, Mikhail, E-mail: m_artemyev@yahoo.com

    2015-07-09

    Highlights: • HgSe magic-sized clusters were prepared via Cd/Hg cationic exchange in pyridine. • Upon cationic exchange CdSe clusters behave differently from quantum dots or rods. • Theoretical calculations of magic-sized clusters agree well with experimental data. - Abstract: We examine conversion of magic-sized CdSe clusters (MSCs) into HgSe ones by means of Cd/Hg cation exchange. With this procedure Cd{sub 8}Cd{sub 17}– and Cd{sub 32}–selenide clusters can be converted into corresponding Hg{sub 8}–, Hg{sub 17}– and Hg{sub 32}–selenide ones. Upon cationic exchange MSCs behavior differs from that of bulkier counterparts – larger (2–3 nm) quantum dots. Unlike CdSe colloidal quantum dots, magic-sized clusters are converted in fast and complete manner without a formation of intermediate mixed Cd{sub x}Hg{sub 1−x} compounds that was established on the basis of optical absorption spectroscopy and chemical composition analysis. These assumptions were supported by DFT quantum chemical calculations performed for Cd{sub 8}–, Cd{sub 17}– and Hg{sub 8}–, Hg{sub 17}–selenide model clusters. Energies of experimental and calculated optical transitions were compared in order to prove the isostructural character of cationic substitution in magic-sized clusters.

  15. Anion stripping as a general method to create cationic porous framework with mobile anions.

    Science.gov (United States)

    Mao, Chengyu; Kudla, Ryan A; Zuo, Fan; Zhao, Xiang; Mueller, Leonard J; Bu, Xianhui; Feng, Pingyun

    2014-05-28

    Metal-organic frameworks (MOFs) with cationic frameworks and mobile anions have many applications from sensing, anion exchange and separation, to fast ion conductivity. Despite recent progress, the vast majority of MOFs have neutral frameworks. A common mechanism for the formation of neutral frameworks is the attachment of anionic species such as F(-) or OH(-) to the framework metal sites, neutralizing an otherwise cationic scaffolding. Here, we report a general method capable of converting such neutral frameworks directly into cationic ones with concurrent generation of mobile anions. Our method is based on the differential affinity between distinct metal ions with framework anionic species. Specifically, Al(3+) is used to strip F(-) anions away from framework Cr(3+) sites, leading to cationic frameworks with mobile Cl(-) anions. The subsequent anion exchange with OH(-) further leads to a porous network with mobile OH(-) anions. New materials prepared by anion stripping can undergo ion exchange with anionic organic dyes and also exhibit much improved ionic conductivity compared to the original unmodified MOFs.

  16. 非能动余热排出换热器换热能力数值分析%Numerical Analysis on Heat Removal Capacity of Passive Residual Heat Removal Heat Exchanger

    Institute of Scientific and Technical Information of China (English)

    张文文; 丛腾龙; 田文喜; 秋穗正; 苏光辉; 谢永诚; 蒋兴

    2015-01-01

    Thermal‐hydraulics characteristics of AP1000 passive residual heat removal heat exchanger (PRHR‐HX) at initial operating stage were analyzed based on the por‐ous media model .The data obtained from RELAP5 under the condition of the station blackout was employed as the inlet flow rate and temperature boundary of CFD calcula‐tion .The distribution resistances were added into the C‐type tube bundle region which was treated as porous zone .Three‐dimensional distributions of velocity and temperature in the in‐containment refueling water storage tank (IRWST ) were calculated by the commercial CFD code FLUENT .The heat transfer between the primary loop side and the IRWST side was calculated by user self‐defined function UDF .The results show that the heat transfer capability decreases with the increase of water temperature and a thermal stratification phenomenon in the tank occurs .The present results indicate that the method containing coupled heat transfer from the primary loop side fluid to IRWST side fluid and porous media model is a suitable approach to study the transient thermal‐hydraulics of PRHR/IRWST system .%基于多孔介质模型,对AP1000非能动余热排出换热器(PRHR‐HX)运行初始阶段进行了数值模拟。一回路的入口温度及流量采用RELAP5的计算结果,并以此作为CFD计算的边界条件。采用多孔介质模型处理C型管束区,添加管束区分布阻力。通过商业CFD软件FLUENT 计算得到安全壳内置换料水箱(IRWST )侧冷却剂的三维温度及速度分布,通过用户自定义函数 UDF 完成一回路侧与IRWST侧的耦合换热计算,获得一回路温度分布及换热量。计算结果表明,随着IRWST 内冷却剂温度升高,换热器热负荷降低,并出现明显的热分层现象,同时证明采用多孔介质模型与耦合换热计算是分析PRHR/IRWST系统瞬态热工水力特性的有效方法。

  17. Afrikaans Syllabification Patterns

    Directory of Open Access Journals (Sweden)

    Tilla Fick

    2010-01-01

    Full Text Available In contrast to English, automatic hyphenation by computer of Afrikaans words is a problem that still needs to be addressed, since errors are still often encountered in printed text. An initial step in this task is the ability to automatically syllabify words. Since new words are created continuously by joining words, it is necessary to develop an “intelligent” technique for syllabification. As a first phase of the research, we consider only the orthographic information of words, and disregard both syntactic and morphological information. This approach allows us to use machine-learning techniques such as artificial neural networks and decision trees that are known for their pattern recognition abilities. Both these techniques are trained with isolated patterns consisting of input patterns and corresponding outputs (or targets that indicate whether the input pattern should be split at a certain position, or not. In the process of compiling a list of syllabified words from which to generate training data for the  syllabification problem, irregular patterns were identified. The same letter patterns are split differently in different words and complete words that are spelled identically are split differently due to meaning. We also identified irregularities in and between  the different dictionaries that we used. We examined the influence range of letters that are involved in irregularities. For example, for their in agter-ente and vaste-rente we have to consider three letters to the left of r to be certain where the hyphen should be inserted. The influence range of the k in verstek-waarde and kleinste-kwadrate is four to the left and three to the right. In an analysis of letter patterns in Afrikaans words we found that the letter e has the highest frequency overall (16,2% of all letters in the word list. The frequency of words starting with s is the highest, while the frequency of words ending with e is the highest. It is important to

  18. International Exchanges

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    On October 12,2015,Mr.Zhu Rui,CPAPD Secretary General,chaired informal discussions with U.S.young experts and scholars on arms control and non-proliferation.The two sides exchanged views on international arms control,disarmament,non-proliferation and nuclear security,etc.During October 12 to 16,2015,at the invitation of the CPAPD,a four-member delegation from the Vietnam Peace Committee headed by its Vice-President Ms.Nguyen Thi Hoang Van

  19. Cationic Dihydrogen/Dihydride Complexes of Osmium: Structure and Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Egbert, Jonathan D.; Bullock, R. Morris; Heinekey, D. M.

    2007-03-22

    Reaction of Cp*Os(CO)2Cl with (Et3Si )(BArF4) under hydrogen gas affords the cationic hydrogen complex [Cp*Os(CO)2(H2)][BArF4] (1), (Cp* = C5Me5; ArF = C6F5). When this reaction is carried out with HD gas, complex 1-d1 results, with JHD = 24.5 Hz. When solutions of complex 1 are monitored by 1H NMR spectroscopy over several days, the gradual formation of a trans dihydride species is observed. Similarly, reaction of CpOs(dppm)Br with NaBArF*4 (ArF* = 3,5-(CF3)2C6H3) under hydrogen affords the cationic dihydride complex [CpOs(dppm)H2]BArF*4 (