Sample records for vi cation exchange

  1. Enhanced photocatalytic activity of chromium(VI) reduction and EDTA oxidization by photoelectrocatalysis combining cationic exchange membrane processes

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hung-Te, E-mail: [Institute of Environmental Engineering and Management, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 106, Taiwan (China); Chen, Shiao-Shing, E-mail: [Institute of Environmental Engineering and Management, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 106, Taiwan (China); Tang, Yi-Fang, E-mail: [Institute of Environmental Engineering and Management, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 106, Taiwan (China); Hsi, Hsing-Cheng, E-mail: [Institute of Environmental Engineering and Management, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 106, Taiwan (China)


    Highlights: ► Chromium(VI) reduction and EDTA oxidization were conducted by photoelectrocatalysis. ► Apply the concept of cationic exchange membrane to enhance the conversion efficiency. ► The optimum TiO{sub 2} loading of 1 g/L was observed at acidic pH with current density 4 mA/cm{sup 2}. ► Transformation pathway of EDTA was determined from analyzed byproducts and molecular orbital package analysis. -- Abstract: A novel technology of photoelectrocatalysis (PEC) combining with cationic exchange membrane (CEM) was proposed for simultaneous reduction of chromium(VI) and oxidization of EDTA. The application of CEM was used to enhance the efficiency for prevention of the re-oxidation of reduced chromium with the electron–hole pairs. In this study, effects of current density, pH, TiO{sub 2} dosage, hydraulic retention time (HRT), light intensity and EDTA/Cr(VI) molar ratio were all investigated. The results showed that the optimum conversion efficiency occurred at 4 mA/cm{sup 2} with the presence of CEM. Higher conversion efficiencies were observed at lower pH due to the electrostatic attractions between positive charged Ti-OH{sub 2}{sup +}, and negatively charged Cr(VI) and EDTA. The optimum TiO{sub 2} loading of 1 g/L was depended mainly on the acidic pH range, especially at higher HRT and irradiation intensity. In addition, higher EDTA/Cr(VI) molar ratio enhanced the reduction efficiency of Cr(VI), indicating EDTA plays the role of hole scavenger in this system. Moreover, incomplete EDTA decomposition contributes to the occurrence of intermediates, including nitrilotriacetic acid, iminodiacetic acid, glycine, oxamic acid, lyoxylic acid, oxalic acid, acetic acid and formic acid, as identified by GC/MS. Consequently, transformation pathway was determined from these analyzed byproducts and molecular orbital package analysis.

  2. 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)


    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.

  3. Forging Colloidal Nanostructures via Cation Exchange Reactions (United States)


    Among the various postsynthesis treatments of colloidal nanocrystals that have been developed to date, transformations by cation exchange have recently emerged as an extremely versatile tool that has given access to a wide variety of materials and nanostructures. One notable example in this direction is represented by partial cation exchange, by which preformed nanocrystals can be either transformed to alloy nanocrystals or to various types of nanoheterostructures possessing core/shell, segmented, or striped architectures. In this review, we provide an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange. At the same time, the review gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions, as they are currently understood, and outlines the main open issues and possible future developments in the field. PMID:26891471

  4. Transport of divalent cations: cation exchange capacity of intact xylem vessels. (United States)

    Van de Geijn, S C; Petit, C M


    The cation exchange capacity of the intact xylem vessels in cut shoots of papyrus (Cyperus papyrus spec.) has been determined. The cation exchange capacity is independent of the cation concentration in the transpiration stream, and is equal for Ca and Co. The high value of the cation exchange capacity (0.6 to 1 x 10(-7) equivalents per square centimeter vessel wall surface) leads to the hypothesis that the porous structure of the vessel wall, and not only the inner vessel wall surface, acts as a cation exchanger.Differences between anion ([(32)P]phosphate, [(45)Ca]EDTA(2-), [(115)Cd(m)]-EDTA(2-)), and cation ([(45)Ca](2+), [(115)Cd(m)](2+)) movement are explained in terms of transport with the transpiration flux or by exchange reactions. The competition between exchange sites and natural or synthetic ligands for the divalent cations is discussed.

  5. Cation exchange properties of zeolites in hyper alkaline aqueous media. (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


    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.

  6. Fabrication of Cationic Exchange Polystyrene Nanofibers for Drug ...

    African Journals Online (AJOL)

    Purpose: To prepare polystyrene nanofiber ion exchangers (PSNIE) with surface cation exchange functionality using a new method based on electrospinning and also to optimize crosslinking and sulfonation reactions to obtain PSNIE with maximum ion exchange capacity (IEC). Method: The nanofibers were prepared from ...

  7. A Scale Model of Cation Exchange for Classroom Demonstration. (United States)

    Guertal, E. A.; Hattey, J. A.


    Describes a project that developed a scale model of cation exchange that can be used for a classroom demonstration. The model uses kaolinite clay, nails, plywood, and foam balls to enable students to gain a better understanding of the exchange complex of soil clays. (DDR)

  8. Isolation of polybutenylsuccinimide-type dispersants from multigrade lubricating oils by classical cation exchange chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Hui, F.; Machtalere, G.; Xie, J.; Kolodziejczyk, H.; Rosset, R. [Laboratoire de Chimie Analytique, URA CNRS 437, Ecole Superieure de Physique et Chimie Industrielles de la Ville de Paris, Paris (France)


    A macroporous cation exchanger is used for the efficient separation of ashless dispersants (polybutenylsuccinimide type) from base oil and additives (viscosity improver (VI), detergent, inhibitors, etc.) of multigrade lubricating oils. Due to the basic character of residual amine groups present in its polyamine chain, the dispersant is retained on the macroporous cation exchanger (H{sup +} form) while base oil and additives are eluted with appropriate solvents. The highly purified dispersant is then recovered through elution with a strong and basic eluent constituted of chloroform-isopropanol-ammonia (35:60:5, v/v). The quality of the isolation is checked all along the separation by Fourier transform infrared (FTIR) spectrometry and size-exclusion chromatography (SEC)

  9. Atomic models for anionic ligand passivation of cation-rich surfaces of IV-VI, II-VI, and III-V colloidal quantum dots. (United States)

    Ko, Jae-Hyeon; Yoo, Dongsuk; Kim, Yong-Hyun


    We formulated atomic models of cation-rich surfaces passivated with anionic ligands for IV-VI, II-VI, and III-V colloidal quantum dots, employing electron counting models and quantum mechanical calculations. We found that the fractional dangling bonds of cation-rich (100) and (111) surfaces could be greatly stabilized by dimerization-anion passivation and amine-anion co-passivation.

  10. High-speed simultaneous ion-exclusion/cation-exchange chromatography of anions and cations on a weakly acidic cation-exchange resin column. (United States)

    Mori, Masanobu; Tanaka, Kazuhiko; Helaleh, Murad I H; Xu, Qun; Ikedo, Mikaru; Ogura, Yutaka; Sato, Shinji; Hu, Wenzhi; Hasebe, Kiyoshi; Haddad, Paul R


    The simultaneous ion-exclusion/cation-exchange separation column packed with a polymethacrylate-based weakly acidic cation-exchange resin of 3 microm particle size was used to achieve the simultaneous high-speed separation of anions and cations (Cl(-), NO3(-), SO4(2-), Na(+), K(+), NH4(+), Ca(2+) and Mg(2+)) commonly found in environmental samples. The high-speed simultaneous separation is based on a combination of the ion-exclusion mechanism for the anions and the cation-exchange mechanism for cations. The complete separation of the anions and cations was achieved in 5 min by elution with 15 mM tartaric acid-2.5 mM 18-crown-6 at a flow-rate of 1.5 ml/min. Detection limits at S/N=3 ranged from 0.36 to 0.68 microM for anions and 0.63-0.99 microM for cations. This method has been applied to the simultaneous determination of anions and cations in several environmental waters with satisfactory results.

  11. Esterification of maleic acid and butanol using cationic exchange ...

    Indian Academy of Sciences (India)

    Dibutyl maleate is a perfumery ester used as an intermediate in the production of paints, adhesives, and copolymers. Esterification of maleic acid and butanol was studied in presence of acidic cation exchange resin as a catalyst. The objective of this work was to test the suitability and efficacy of heterogeneous catalystssuch ...

  12. Esterification of maleic acid and butanol using cationic exchange ...

    Indian Academy of Sciences (India)



    Nov 15, 2017 ... Abstract. Dibutyl maleate is a perfumery ester used as an intermediate in the production of paints, adhesives, and copolymers. Esterification of maleic acid and butanol was studied in presence of acidic cation exchange resin as a catalyst. The objective of this work was to test the suitability and efficacy of ...

  13. Selective oxidation of propane over cation exchanged zeolites

    NARCIS (Netherlands)

    Xu, J.


    This thesis focuses on investigation of the fundamental knowledge on a new method for selective oxidation of propane with O2 at low temperature (< 100°C). The relation between propane catalytic selective oxidation and physicochemical properties of cation exchanged Y zeolite has been studied. An

  14. Removal of dioxouran (VI) cations from aqueous solution by natural sorbents (United States)

    Naumova, Lyudmila; Gorlenko, Nikolai; Sarkisov, Yurii; Tsvetkov, Nikolai; Shepelenko, Tat'yana; Chukhlomina, Lyudmila


    The paper presents investigations of the mechanism of UO22+ cation sorption by natural zeolites and peat from aqueous solutions using a limited volume method. It is proved that the sorption rate depends on sorbent granulating, dioxouran (VI) temperature and concentration. The results show that sorption of UO22+ cations by natural sorbents is the mixed-diffusional mechanism. The use of 24-hour interruption technique (`kinetic memory') demonstrates that in the mixed-diffusional mechanism for natural peat and zeolites the internal ion diffusion predominates. The coefficients of internal diffusion and activation energy are calculated in this paper. The infrared spectroscopy technique and synchronous thermal test are used to identify the interaction between dioxouran (VI) and energy components of natural sorbents. The synchronous thermal test shows that UO22+ cation sorption decreases the thermal stability of peat as compared to its original state. The peat decomposition is determined after UO22+ cation removal as well as the appearance of end-effect maximum of 777.5°C. An assumption is made on a possible decomposition of different metal oxalates in peat and clay peat bonds which irreversibly absorb UO22+ cations. These research findings can be recommended for water purification at nuclear fuel cycle facility.

  15. Column study of Cr(VI) removal by cationic hydrogel for in-situ remediation of contaminated groundwater and soil. (United States)

    Tang, Samuel C N; Yin, Ke; Lo, Irene M C


    Column experiments were conducted for examining the effectiveness of the cationic hydrogel on Cr(VI) removal from groundwater and soil. For in-situ groundwater remediation, the effects of background anions, humic acid (HA) and pH were studied. Cr(VI) has a higher preference for being adsorbed onto the cationic hydrogel than sulphate, bicarbonate ions and HA. However, the adsorbed HA reduced the Cr(VI) removal capacity of the cationic hydrogel, especially after regeneration of the adsorbents, probably due to the blockage of adsorption sites. The Cr(VI) removal was slightly influenced by the groundwater pH that could be attributed to Cr(VI) speciation. The 6-cycle regeneration and reusability study shows that the effectiveness of the cationic hydrogel remained almost unchanged. On average, 93% of the adsorbed Cr(VI) was recovered in each cycle and concentrated Cr(VI) solution was obtained after regeneration. For in-situ soil remediation, the flushing water pH had an insignificant effect on the release of Cr(VI) from the soils. Multiple-pulse flushing increased the removal of Cr(VI) from the soils. In contrast, more flushing water and longer operation may be required to achieve the same removal level by continuous flushing. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Alloyed copper chalcogenide nanoplatelets via partial cation exchange reactions. (United States)

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


    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.

  17. Exchangeable cations in some soils of Mt. Stara planina

    Directory of Open Access Journals (Sweden)

    Belanović Snežana


    Full Text Available Land use in forest and pasture ecosystems requires the respecting of ecological and economic interactions between the individual components of these ecosystems. The content of nutrition elements in the soil solution depends on soil types, climate conditions and vegetation species, i.e., it is conditioned by their cycling in the ecosystem. This paper studies the cation exchange capacity in pasture and forest soils of Mt. Stara Planina.

  18. Simultaneous separation of inorganic anions and cations by using anion-exchange and cation-exchange columns connected in tandem in ion chromatography. (United States)

    Karim, Khairil Juhanni Binti Abd; Jin, Ji-Ye; Takeuchi, Toyohide


    Inorganic anions and cations in environmental waters were determined by ion chromatography. Stationary and mobile phases were examined for the simultaneous separation of both anions and cations. Cations detection by UV detection requires a mobile phase with a UV absorbing additive, which indirectly visualizes cations as negative peaks. Simultaneous separation of anions and cations were achieved when using an eluent that consists of inorganic acid with weak basic amino acid as additives. It was convenient to separate both anions and cations by coupling anion-exchange and cation-exchange columns in tandem. The order of the separation columns connected affected the elution profiles. When the eluent comprises of multiple anions and a single cation, the anion-exchange column should be connected in the upper stream, whereas when the eluent comprises multiple cations and a single anion, the cation-exchange column should be connected in the upper stream. Use of switching valves also allowed simultaneous separation of anions and cations in a single chromatographic run. In the present work, operating conditions were optimized for the simultaneous separation of anions and cations.

  19. 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


    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

  20. Selective organic synthesis over metal cation-exchanged clay catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Tateiwa, J.; Uemura, S. [Kyoto University, Kyoto (Japan)


    Results of recent studies conducted by the authors are reviewed on the use, as catalysts, of metal cation-exchanged montmorillonite (M{sup n+}-mont), a modified natural clay with a layer structure, and metal cation-exchanged fluor-tetrasilicic mica (M{sup n+}-TSM), a synthetic clay with a layer structure, for the following organic synthesis: (1) Friedel-Crafts alkylation of phenol with 4-hydroxybutan-2-one to produce 4-(4-hydroxyphenyl)butan-2-one (raspberry ketone), (2) rearrangement of alkyl phenyl ethers to corresponding alkylphenols, (3) aromatic alkylation of phenol with aldehydes and ketones to produce corresponding gem-bis(hydroxyphenyl)alkanes (bisphenols) and alkylphenols, respectively, (4) a facile and an almost quantitative substrate-selective acetalization, (5) alkane oxidation with aqueous tert-butyl hydroperoxide, (6) Prins reaction of styrenes with aldehydes using clay as a Bronsted acid, and (7) inter-and intra-molecular carbonyl-ene reaction using clay as a Lewis acid in condition similar to that of Prins reaction. In almost all cases, the clay catalysts could be regenerated and reused several times, after filtration, washing and drying. 42 refs., 20 figs., 3 tabs.

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

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Santanu; Dang, Liem X.


    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.

  2. [Study on the defluoridation of drinking water with model-La cation exchange resin]. (United States)

    Huang, Mingyuan; Lü, Changyin


    Model-La cation exchange resin was transformed from strong acid cation exchange resin, which was used for the defluoridation of drinking water. The 001 x 7 strong acid cation exchange resin was transformed into model-La cation exchange by soaking in the La(NO3)3 solution. The F- in the water was removed by model-La cation exchange resin under the optimum condition because it was combined into fluoride with the La3+ in the model-La cation exchange resin. The used resin was regenerated with the La(NO3)3 solution and was used to defluoridate many times. The optimum conditions of transform and defluoridation and regeneration were d(rasin) = 0.315-0.600 mm, V(rasin):V(regeneration) = 1:6, t(transform) = 48 h, T = 298.16 K(25 degrees C). The defluoridation capacity was 5.60 mg/g in column test, and 4.08 mg/g in batch test. The model-La cation exchange resin could be used for defluoridation for 8 times. The results suggest that the model-La cation exchange resin is a novel material of defluoridation. This method is easy to master and the pH value of the solution doesn't need to be regenerated that the cost of defluoridation can be reduced significantly and it can be used for a long time.

  3. Exciton dynamics in cation-exchanged CdSe/PbSe nanorods: The role of defects (United States)

    Lee, Sooho; Wang, Yimeng; Liu, Yawei; Lee, Dongkyu; Lee, Kangha; Lee, Doh C.; Lian, Tianquan


    Cation exchange occurs via defect initiated solid-state diffusion, a process that can lead to defect formations. The effect of such inherent defect formation on carrier dynamics of cation-exchanged heterostructures remains poorly understood. Herein, we report exciton dynamics in type II CdSe/PbSe heterostructure nanorods formed via cation exchange. The majority of electrons in CdSe domains decays in 5 ps due to ultrafast carrier trapping. The defect generated by cation exchange can be healed by annealing the as-synthesized CdSe/PbSe heterostructure nanorods. This study suggests a strategy for improving properties of heteronanostructures prepared by cation exchange for applications in photovoltaics and photocatalysis.

  4. Cation Exchange Capacity of Biochar: An urgent method modification (United States)

    Munera, Jose; Martinsen, Vegard; Mulder, Jan; Tau Strand, Line; Cornelissen, Gerard


    A better understanding of the cation exchange capacity (CEC) values of biochar and its acid neutralizing capacity (ANC) is crucial when tailoring a single biochar for a particular soil and crop. Literature values for the CEC of biochar are surprisingly variable, commonly ranging from 5 to 50 cmol+/Kg even as high as 69 to 204 cmol+/Kg and often poorly reproducible, suggesting methodological problems. Ashes and very fine pores in biochar may complicate the analysis and thus compromise the results. Here, we modify and critically assess different steps in a common method for CEC determination in biochar and investigate how the measured CEC may be affected by slow cation diffusion from micro-pores. We modified the existing ammonium acetate (NH4-OAc) method (buffered at pH 7), based on displaced ammonium (NH4+) in potassium chloride (KCl) extracts after removing excess NH4-OAc with alcohol in batch mode. We used pigeon pea biochar (produced at 350 ˚C; particle size 0.5mm to 2mm) to develop the method and we tested its reproducibility in biochars with different ANC. The biochar sample (1.00g) was pH-adjusted to 7 after 2 days of equilibration, using hydrochloric acid (HCl), and washed with water until the conductivity of the water was replacing cations (NH4+ and K+) in micro-pores, we equilibrated the biochar with NH4-OAc for 1 and 7 days, and after washing with alcohol, for 1, 3 and 7 days with KCl. The effects of the washing volume of alcohol (15, 30 and 45 ml) and of the biochar to NH4OAc solution ratio (1:15, 1:30 and 1:45) were also tested. The CEC values were corrected for dry matter content and mass losses during the process. Results indicate that the measured CEC values of the modified method were highly reproducible and that 1 day shaking with NH4OAc and KCl is enough to saturate the exchange sites with NH4+ and subsequently with K+. The biochar to NH4OAc solution ratio did not affect the measured CEC. Three washings with at least 15 ml alcohol are required to

  5. Bifluoride-catalysed sulfur(VI) fluoride exchange reaction for the synthesis of polysulfates and polysulfonates (United States)

    Gao, Bing; Zhang, Linda; Zheng, Qinheng; Zhou, Feng; Klivansky, Liana M.; Lu, Jianmei; Liu, Yi; Dong, Jiajia; Wu, Peng; Sharpless, K. Barry


    Polysulfates and polysulfonates possess exceptional mechanical properties making them potentially valuable engineering polymers. However, they have been little explored due to a lack of reliable synthetic access. Here we report bifluoride salts (Q+[FHF]-, where Q+ represents a wide range of cations) as powerful catalysts for the sulfur(VI) fluoride exchange (SuFEx) reaction between aryl silyl ethers and aryl fluorosulfates (or alkyl sulfonyl fluorides). The bifluoride salts are significantly more active in catalysing the SuFEx reaction compared to organosuperbases, therefore enabling much lower catalyst-loading (down to 0.05 mol%). Using this chemistry, we are able to prepare polysulfates and polysulfonates with high molecular weight, narrow polydispersity and excellent functional group tolerance. The process is practical with regard to the reduced cost of catalyst, polymer purification and by-product recycling. We have also observed that the process is not sensitive to scale-up, which is essential for its future translation from laboratory research to industrial applications.

  6. Cation immobilization in pyrolyzed simulated spent ion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Luca, Vittorio, E-mail: [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)


    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

  7. Removal of chromium from Cr(VI) polluted wastewaters by reduction with scrap iron and subsequent precipitation of resulted cations. (United States)

    Gheju, M; Balcu, I


    This work presents investigations on the total removal of chromium from Cr(VI) aqueous solutions by reduction with scrap iron and subsequent precipitation of the resulted cations with NaOH. The process was detrimentally affected by a compactly passivation film occurred at scrap iron surface, mainly composed of Cr(III) and Fe(III). Maximum removal efficiency of the Cr(total) and Fe(total) achieved in the clarifier under circumneutral and alkaline (pH 9.1) conditions was 98.5% and 100%, respectively. The optimum precipitation pH range which resulted from this study is 7.6-8.0. Fe(total) and Cr(total) were almost entirely removed in the clarifier as Fe(III) and Cr(III) species; however, after Cr(VI) breakthrough in column effluent, chromium was partially removed in the clarifier also as Cr(VI), by coprecipitation with cationic species. As long the column effluent was free of Cr(VI), the average Cr(total) removal efficiency of the packed column and clarifier was 10.8% and 78.8%, respectively. Our results clearly indicated that Cr(VI) contaminated wastewater can be successfully treated by combining reduction with scrap iron and chemical precipitation with NaOH. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Synthesis and characterization of a homogeneous and silica supported homoleptic cationic tungsten(vi) methyl complex: application in olefin metathesis

    KAUST Repository

    Dey, Raju


    A method for the synthesis of a homogeneous cationic tungsten(VI)penta-methyl complex [(WMe5)(+)(C6F5)(3)BMe-] from neutral tungstenhexamethyl (WMe6) and a silica supported cationic tungstentetramethyl complex [( Si-O-)WMe4+ (C6F5)(3)BMe-] from a neutral silica supported tungstenpentamethyl complex [( Si-O-)WMe5] is described. In both cases a direct demethylation using the B(C6F5)(3) reagent was used. The aforesaid complexes were characterized by liquid or solid state NMR spectroscopy. Interestingly, the homogeneous cationic complex [(WMe5)(+)(C6F5)(3)BMe-] shows moderate activity whereas the supported cationic complex [( Si-O-)WMe4+(C6F5)(3)BMe-] exhibits good activity in olefin metathesis reactions.

  9. Synthesis and characterization of a homogeneous and silica supported homoleptic cationic tungsten(vi) methyl complex: application in olefin metathesis. (United States)

    Dey, Raju; Samantaray, Manoja K; Poater, Albert; Hamieh, Ali; Kavitake, Santosh; Abou-Hamad, Edy; Callens, Emmanuel; Emwas, Abdul-Hamid; Cavallo, Luigi; Basset, Jean-Marie


    A method for the synthesis of a homogeneous cationic tungsten(vi)pentamethyl complex [(WMe5)(+)(C6F5)3BMe(-)] from neutral tungstenhexamethyl (WMe6) and a silica supported cationic tungstentetramethyl complex [([triple bond, length as m-dash]Si-O-)WMe4(+) (C6F5)3BMe(-)] from a neutral silica supported tungstenpentamethyl complex [([triple bond, length as m-dash]Si-O-)WMe5] is described. In both cases a direct demethylation using the B(C6F5)3 reagent was used. The aforesaid complexes were characterized by liquid or solid state NMR spectroscopy. Interestingly, the homogeneous cationic complex [(WMe5)(+)(C6F5)3BMe(-)] shows moderate activity whereas the supported cationic complex [([triple bond, length as m-dash]Si-O-)WMe4(+)(C6F5)3BMe(-)] exhibits good activity in olefin metathesis reactions.

  10. Exploring backbone-cation alkyl spacers for multi-cation side chain anion exchange membranes (United States)

    Zhu, Liang; Yu, Xuedi; Hickner, Michael A.


    In order to systematically study how the arrangement of cations on the side chain and length of alkyl spacers between cations impact the performance of multi-cation AEMs for alkaline fuel cells, a series of polyphenylene oxide (PPO)-based AEMs with different cationic side chains were synthesized. This work resulted in samples with two or three cations in a side chain pendant to the PPO backbone. More importantly, the length of the spacer between cations varied from 3 methylene (-CH2-) (C3) groups to 8 methylene (C8) groups. The highest conductivity, up to 99 mS/cm in liquid water at room temperature, was observed for the triple-cation side chain AEM with pentyl (C5) or hexyl (C6) spacers. The multi-cation AEMs were found to have decreased water uptake and ionic conductivity when the spacer chains between cations were lengthened from pentyl (C5) or hexyl (C6) to octyl (C8) linking groups. The triple-cation membranes with pentyl (C5) or hexyl (C6) groups between cations showed greatest stability after immersion in 1 M NaOH at 80 °C for 500 h.

  11. 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:


    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.

  12. Preparation of Cd/Pb Chalcogenide Heterostructured Janus Particles via Controllable Cation Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianbing; Chernomordik, Boris D.; Crisp, Ryan W.; Kroupa, Daniel M.; Luther, Joseph M.; Miller, Elisa M.; Gao, Jianbo; Beard, Matthew C.


    We developed a strategy for producing quasi-spherical nanocrystals of anisotropic heterostructures of Cd/Pb chalcogenides. The nanostructures are fabricated via a controlled cation exchange reaction where the Cd2+ cation is exchanged for the Pb2+ cation. The cation exchange reaction is thermally activated and can be controlled by adjusting the reaction temperature or time. We characterized the particles using TEM, XPS, PL, and absorption spectroscopy. With complete exchange, high quality Pb-chalcogenide quantum dots are produced. In addition to Cd2+, we also find suitable conditions for the exchange of Zn2+ cations for Pb2+ cations. The cation exchange is anisotropic starting at one edge of the nanocrystals and proceeds along the <111> direction producing a sharp interface at a (111) crystallographic plane. Instead of spherical core/shell structures, we produced and studied quasi-spherical CdS/PbS and CdSe/PbSe Janus-type heterostructures. Nontrivial PL behavior was observed from the CdS(e)/PbS(e) heterostructures as the Pb:Cd ratio is increased.

  13. Atomistic understanding of cation exchange in PbS nanocrystals using simulations with pseudoligands

    NARCIS (Netherlands)

    Fan, Z.; Lin, L.; Buijs, W.; Vlugt, T.J.H.; van Huis, MA


    Cation exchange is a powerful tool for the synthesis of nanostructures such as core–shell nanocrystals, however, the underlying mechanism is poorly understood. Interactions of cations with ligands and solvent molecules are systematically ignored in simulations. Here, we introduce the concept of

  14. Cation exchange assisted binding-elution strategy for enzymatic synthesis of human milk oligosaccharides (HMOs). (United States)

    Zhu, Hailiang; Wu, Zhigang; Gadi, Madhusudhan Reddy; Wang, Shuaishuai; Guo, Yuxi; Edmunds, Garrett; Guan, Wanyi; Fang, Junqiang


    A cation exchange assisted binding-elution (BE) strategy for enzymatic synthesis of human milk oligosaccharides (HMOs) was developed. An amino linker was used to provide the cation ion under acidic condition which can be readily bound to cation exchange resin and then eluted off by saturated ammonium bicarbonate. Ammonium bicarbonate in the collections was easily removed by vacuum evaporation. This strategy circumvented the incompatible issue between glycosyltransferases and solid support or large polymers, and no purification was needed for intermediate products. With current approach, polyLacNAc backbones of HMOs and fucosylated HMOs were synthesized smoothly. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Monovalent and bivalent cations exchange isotherms for faujasites X and Y. (United States)

    Khabzina, Y; Laroche, C; Pagis, C; Farrusseng, D


    This study addresses the modeling of exchange isotherms for faujasite-type zeolites X and Y with K(+), Cs(+), Ca(2+) and Ba(2+) cations based on a large experimental dataset obtained under operating conditions of 0.5 N total normality and an exchange temperature of 80 °C. The isotherm models are based on the mass action law. Ideal solution phase is assumed. Heterogeneity of the solid phase is taken into account by using Barrer and Klinowski's approach to multi-site exchange. Three types of exchange sites are identified on these zeolites. To each exchange site j corresponds a fitted selectivity coefficient Kj. These parameters, estimated by least square method, evaluate the affinity of the studied cations for the identified exchange site. Globally, these fitted coefficients show that the cations considered present better affinity than Na(+), especially for type III sites in faujasite X and type II sites in faujasite Y. For bivalent cations, an exchange with Ba(2+) is always more favorable than with Ca(2+). On faujasite X, type II sites are more strongly preferred by monovalent cations (with the exception of Cs(+)) than by bivalent ones. The opposite trend is observed on faujasite Y, even for Cs(+). These conclusions have been confirmed and are supported by bibliographic data.

  16. Ion Exchange Chromatography-Indirect Ultraviolet Detection for Separation and Determination of Morpholinium Ionic Liquid Cations. (United States)

    Zhang, Yu; Ma, Yajie; Yu, Hong; Liu, Yongqiang


    A rapid analytical method of ion exchange chromatography with indirect ultraviolet detection was developed to determine morpholinium ionic liquid (IL) cations, i.e. N-methyl-N-ethyl morpholinium cation ([MEMo]+) and N-methyl-N-propyl morpholinium cation ([MPMo]+). Chromatographic separation of morpholinium cations was performed on a sulfonic acid base cation exchange column using imidazolium ionic liquid-organic solvent as mobile phase. The effects of chromatographic columns, ultraviolet absorption reagents, imidazolium ILs, detection wavelength, organic solvents, pH values of the mobile phase and column temperature on the retention of morpholinium cations were investigated. The retention times of the cations were clearly decreased by the increase of the alkyl substituent length on imidazolium cation or with the increase of the concentration of 1-ethyl-3-methyl imidazolium tetrafluoroborate. The molecular structure of the anion of imidazolium IL which has UV absorption has influence on determination of the analytes. Under the optimal conditions, the detection limits (signal-to-noise ratio, S/N = 3) were 0.29 and 0.44 mg L-1 The method has been successfully applied to the determination of two ILs synthesized by chemistry laboratory. The method uses the liquid chromatography system, which is widely available in general laboratories, and the simple composition of mobile phase, thus make the quantitative analysis of no UV absorption morpholinium cations possible. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email:

  17. 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.


    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

  18. Performance analysis of cation and anion exchangers in water treatment plant: an industrial case study

    National Research Council Canada - National Science Library

    Ramzan, Naveed; Feroze, Nadeem; Kazmi, Mohsin; Ashraf, Muhammad Arsalan; Hasan, Sajid


    ...% for cation, primary and secondary anion exchangers respectively. The operating time of the water treatment train was significantly increased by achieving adequate capacity utilization of secondary anion exchanger. The low capacity utilization of secondary anion resin due to early silica slippage, has been discussed in the paper.

  19. Characterization and cation exchange capacity of seeds of Ziziphus spina-christi

    Directory of Open Access Journals (Sweden)

    Shadia M. Sirry


    Full Text Available There are several naturally existing materials have ability to utilize as ion-exchangers. Most of these materials are by-products of waste material from industry or agriculture. Agriculture ion exchange materials include: lemon orange, grapefruit, apple, peas, broad bean, and meddler peels, kernel core, and grape skins. This research deals with the utilization of agriculture waste biomass of napak seed as natural cation exchanger for removal of cationic pollutant from aqueous solution. Methylene blue dye method was used to determine the cation exchange capacity of the stone and it was characterized by IR and TGA methods. The results showed that the highest dye sorption capacity was found at pH 7, the equilibrium time was 60 min, sorbent dose = 0.1g, particle size 177μm and methylene blue concentration range 10-50 ppm. The equilibrium sorption data were analyzed by Langmuir and Freundlich isotherm models.

  20. Measurement of cation exchange capacity (CEC) on natural zeolite by percolation method (United States)

    Wiyantoko, Bayu; Rahmah, Nafisa


    The cation exchange capacity (CEC)measurement has been carried out in natural zeolite by percolation method. The natural zeolite samples used for cation exchange capacity measurement were activated beforehand with physical activation and chemical activation. The physically activated zeolite was done by calcination process at 600 °C for 4 hours. The natural zeolite was activated chemically by using sodium hydroxide by refluxing process at 60-80 °C for 3 hours. In summary, cation exchange capacity (CEC) determination was performed by percolation, distillation and titration processes. Based on the measurement that has been done, the exchange rate results from physical activated and chemical activated of natural zeolite were 181.90cmol (+)/kg and 901.49cmol (+)/kg respectively.

  1. Cation exchange applications of synthetic tobermorite for the ...

    Indian Academy of Sciences (India)

    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 ...

  2. Tree species affect cation exchange capacity (CEC) and cation binding properties of organic matter in acid forest soils. (United States)

    Gruba, Piotr; Mulder, Jan


    Soil organic matter (SOM) in forest soil is of major importance for cation binding and acid buffering, but its characteristics may differ among soils under different tree species. We investigated acidity, cation exchange properties and Al bonding to SOM in stands of Scots pine, pedunculate oak, Norway spruce, European beech and common hornbeam in southern Poland. The content of total carbon (Ct) was by far the major contributor to total cation exchange capacity (CECt) even in loamy soils and a strong relationship between Ct and CECt was found. The slope of the regression of CECt to Ct increased in the order hornbeam≈oakvalue in the acid pH range was smallest for hornbeam and oak, and largest for spruce and pine soils. This was supported by the apparent dissociation constant (pKapp) values of SOM, which were largest in soils under oak. The maximum values of Al saturation were similar between the stands. However, maximum Al bonding to SOM occurred at higher pH values in soils under pine and spruce than under oak. Therefore, at any value in the acid pH range, the SOM in pine soil has less Al complexed and more adsorbed H+ than SOM from oak soils. Such differences in Al and H bonding are not only important for pH buffering and metal solubility controls, but also for stabilization of SOM via saturation of functional groups by Al and H. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Sulfonated hydrocarbon graft architectures for cation exchange membranes

    DEFF Research Database (Denmark)

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


    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...

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


    Yin-lin Lei; Yun-jie Luo; Fei Chen; Le-he Mei


    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...

  5. Synthesis and adsorption properties of the cation exchange forms of OFF-type zeolite (United States)

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


    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.

  6. Thermochemical Stability Study of Alkyl-Tethered Quaternary Ammonium Cations for Anion Exchange Membrane Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Angela D.; Tignor, Steven E.; Sturgeon, Matthew R.; Long, Hai; Pivovar, Bryan S.; Bae, Chulsung


    The increased interest in the use of anion exchange membranes (AEMs) for applications in electrochemical devices has prompted significant efforts in designing materials with robust stability in alkaline media. Most reported AEMs suffer from polymer backbone degradation as well as cation functional group degradation. In this report, we provide comprehensive experimental investigations for the analysis of cation functional group stability under alkaline media. A silver oxide-mediated ion exchange method and an accelerated stability test in aqueous KOH solutions at elevated temperatures using a Parr reactor were used to evaluate a broad scope of quaternary ammonium (QA) cationic model compound structures, particularly focusing on alkyl-tethered cations. Additionally, byproduct analysis was employed to gain better understanding of degradation pathways and trends of alkaline stability. Experimental results under different conditions gave consistent trends in the order of cation stability of various QA small molecule model compounds. Overall, cations that are benzyl-substituted or that are near to electronegative atoms (such as oxygen) degrade faster in alkaline media in comparison to alkyl-tethered QAs. These comprehensive model compound stability studies provide valuable information regarding the relative stability of various cation structures and can help guide researchers towards designing new and promising candidates for AEM materials.

  7. Evaluation of Soil Reaction, Exchangeable Acidity and Cation ...

    African Journals Online (AJOL)

    Adequate application of both organic and inorganic fertilizers will improve the organic matter content which will increase the level of CEC of the soils and also liming was recommended to rise the pH of the soils for enhanced production capacity in the study area. Keywords: Exchangeable Acidity, Soil, Pedons and Fertility ...

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

    Directory of Open Access Journals (Sweden)

    Yin-lin Lei


    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.

  9. [Determination of soil exchangeable base cations by using atomic absorption spectrophotometer and extraction with ammonium acetate]. (United States)

    Zhang, Yu-ge; Xiao, Min; Dong, Yi-hua; Jiang, Yong


    A method to determine soil exchangeable calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na) by using atomic absorption spectrophotometer (AAS) and extraction with ammonium acetate was developed. Results showed that the accuracy of exchangeable base cation data with AAS method fits well with the national standard referential soil data. The relative errors for parallel samples of exchangeable Ca and Mg with 66 pair samples ranged from 0.02%-3.14% and 0.06%-4.06%, and averaged to be 1.22% and 1.25%, respectively. The relative errors for exchangeable K and Na with AAS and flame photometer (FP) ranged from 0.06%-8.39% and 0.06-1.54, and averaged to be 3.72% and 0.56%, respectively. A case study showed that the determination method for exchangeable base cations by using AAS was proven to be reliable and trustable, which could reflect the real situation of soil cation exchange properties in farmlands.

  10. Plant diseases caused by heavy metals and their phytiatry with cation exchangers

    Directory of Open Access Journals (Sweden)

    C. Van Assche


    Full Text Available The noxious influence of heavy metals as lead, zinc, copper and lead on higher plants and soil fungi was described. Addition to the soil of Levatit cation exchangers consisting of polystyrene porous resins, charged with calcium or manganese in granulated or powdered form, restored normal plant growth and inhibited the uptake of heavy metals ions.

  11. Enhanced desorption of Cs from clays by a polymeric cation-exchange agent. (United States)

    Park, Chan Woo; Kim, Bo Hyun; Yang, Hee-Man; Seo, Bum-Kyoung; Lee, Kune-Woo


    We report on a new approach to increase the removal of cesium from contaminated clays based on the intercalation of a cationic polyelectrolyte into the clay interlayers. A highly charged cationic polyelectrolyte, polyethyleneimine (PEI), was shown to intercalate into the negatively charged interlayers and readily replaced Cs ions adsorbed on the interlayers of montmorillonite. The polycation desorbed significantly more Cs strongly bound to the clay than did single cations. Moreover, additional NH 4 + treatment following the PEI treatment enhanced desorption of Cs ions that were less accessible by the bulky polyelectrolyte. This synergistic effect of PEI with NH 4 + yielded efficient desorption (95%) of an extremely low concentration of radioactive 137 Cs in the clay, which is very difficult to remove by simple cation-exchange methods due to the increased stability of the binding of Cs to the clay at low Cs concentrations. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Conventional resin cation exchangers versus EDI for CACE measurement in power plants. Feasibility and practical field results

    Energy Technology Data Exchange (ETDEWEB)

    Sigrist, Manuel [Swan Systeme AG, Hinwil (Switzerland)


    The conductivity measurement after a cation exchanger in power plants with steam turbines was introduced soon after 1950 by Larson and Lane. Due to the simple measuring principle, the sensitivity to ionic contaminations and to its high reliability, the conductivity measurement after a cation exchanger (CACE) has become the most commonly used online analytical method in power plants with steam generators. Swan has investigated electro deionisation (EDI) as substitution of the conventional cation exchange resin and has developed a new conductivity instrument using this principle. This paper provides a description of the conventional method for cation conductivity measurements as well as of the new AMI CACE using EDI method.

  13. Influence of acidic eluent for retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography on a weakly acidic cation-exchange resin in the H+ -form. (United States)

    Mori, Masanobu; Tanaka, Kazuhiko; Satori, Tatsuya; Ikedo, Mikaru; Hu, Wenzhi; Itabashi, Hideyuki


    Influence of acidic eluent on retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography (ion-exclusion/CEC) were investigated on a weakly acidic cation-exchange resin in the H(+)-form with conductivity. Sensitivities of analyte ions, especially weak acid anions (F(-) and HCOO(-)), were affected with degree of background conductivity level with pK(a1) (first dissociation constant) of acid in eluent. The retention behaviors of anions and cations were related to that of elution dip induced after eluting acid to separation column and injecting analyte sample. These results were largely dependent on the natures of acid as eluent. Through this study, succinic acid as the eluent was suitable for simultaneous separation of strong acid anions (SO(4)(2-), Cl(-), NO(3)(-) and I(-)), weak acid anions (F(-), HCOO(-) and CH(3)COO(-)), and cations (Na(+), K(+), NH(4)(+), Mg(2+) and Ca(2+)). The separation was achieved in 20 min under the optimum eluent condition, 20 mM succinic acid/2 mM 18-crown-6. Detection limits at S/N=3 ranged from 0.10 to 0.51 microM for strong acid anions, 0.20 to 5.04 microM for weak acid anions and 0.75 to 1.72 microM for cations. The relative standard deviations of peak areas in the repeated chromatographic runs (n=10) were in the range of 1.1-2.9% for anions and 1.8-4.5% for cations. This method was successfully applied to hot spring water containing strong acid anions, weak acid anions and cations, with satisfactory results.

  14. Mobile phase modifier effects in multimodal cation exchange chromatography. (United States)

    Holstein, Melissa A; Parimal, Siddharth; McCallum, Scott A; Cramer, Steven M


    This study examines protein adsorption behavior and the effects of mobile phase modifiers in multimodal chromatographic systems. Chromatography results with a diverse protein library indicate that multimodal and ion exchange resins have markedly different protein binding behavior and selectivity. NMR results corroborate the stronger binding observed for the multimodal system and provide insight into the structural basis for the observed binding behavior. Protein-binding affinity and selectivity in multimodal and ion exchange systems are then examined using a variety of mobile phase modifiers. Arginine and guanidine are found to have dramatic effects on protein adsorption, yielding changes in selectivity in both chromatographic systems. While sodium caprylate leads to slightly weaker chromatographic retention for most proteins, certain proteins exhibit significant losses in retention in both systems. The presence of a competitive binding mechanism between the multimodal ligand and sodium caprylate for binding to ubiquitin is confirmed using STD NMR. Polyol mobile phase modifiers are shown to result in increased retention for weakly bound proteins and decreased retention for strongly bound proteins, indicating that the overall retention behavior is determined by a balance between changes in electrostatic and hydrophobic interactions. This work provides an improved understanding of protein adsorption and mobile phase modifier effects in multimodal chromatographic systems and sets the stage for future work to develop more selective protein separation systems. Copyright © 2011 Wiley Periodicals, Inc.

  15. First principles derived, transferable force fields for CO2 adsorption in Na-exchanged cationic zeolites. (United States)

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


    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.

  16. 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


    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...

  17. Fast cation-exchange separation of proteins in a plastic microcapillary disc. (United States)

    Darton, N J; Reis, N M; Mackley, M R; Slater, N K H


    A novel disposable adsorbent material for fast cation-exchange separation of proteins was developed based on plastic microcapillary films (MCFs). A MCF containing 19 parallel microcapillaries, each with a mean internal diameter of 142 μm, was prepared using a melt extrusion process from an ethylene-vinyl alcohol copolymer (EVOH). The MCF was surface functionalized to produce a cation-exchange adsorbent (herein referred as MCF-EVOH-SP). The dynamic binding capacity of the new MCF-EVOH-SP material was experimentally determined by frontal analysis using pure protein solutions in a standard liquid chromatography instrument for a range of superficial flow velocities, u(LS)=5.5-27.7 cm s⁻¹. The mean dynamic binding capacity for hen-egg lysozyme was found to be approximately 100 μg for a 5 m length film, giving a ligand binding density of 413 ng cm⁻². The dynamic binding capacity did not vary significantly over the range of u(LS) tested. The application of this novel material to subtractive chromatography was demonstrated for anionic BSA and cationic lysozyme at pH 7.2. The chromatographic separation of two cationic proteins, lysozyme and cytochrome-c, was also performed with a view to applying this technology to the analysis or purification of proteins. Future applications might include separation based on anion exchange and other modes of adsorption. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. In vivo cation exchange in quantum dots for tumor-specific imaging. (United States)

    Liu, Xiangyou; Braun, Gary B; Qin, Mingde; Ruoslahti, Erkki; Sugahara, Kazuki N


    In vivo tumor imaging with nanoprobes suffers from poor tumor specificity. Here, we introduce a nanosystem, which allows selective background quenching to gain exceptionally tumor-specific signals. The system uses near-infrared quantum dots and a membrane-impermeable etchant, which serves as a cation donor. The etchant rapidly quenches the quantum dots through cation exchange (ionic etching), and facilitates renal clearance of metal ions released from the quantum dots. The quantum dots are intravenously delivered into orthotopic breast and pancreas tumors in mice by using the tumor-penetrating iRGD peptide. Subsequent etching quenches excess quantum dots, leaving a highly tumor-specific signal provided by the intact quantum dots remaining in the extravascular tumor cells and fibroblasts. No toxicity is noted. The system also facilitates the detection of peritoneal tumors with high specificity upon intraperitoneal tumor targeting and selective etching of excess untargeted quantum dots. In vivo cation exchange may be a promising strategy to enhance specificity of tumor imaging.The imaging of tumors in vivo using nanoprobes has been challenging due to the lack of sufficient tumor specificity. Here, the authors develop a tumor-specific quantum dot system that permits in vivo cation exchange to achieve selective background quenching and high tumor-specific imaging.

  19. The colloid fraction and cation-exchange capacity in the soils of Vojvodina, Serbia

    Directory of Open Access Journals (Sweden)

    Nešić Ljiljana


    Full Text Available The colloidal complex of soil consists of humus and clay, the most important acidoids which are able to create the bonds between oppositely charged ions (cations through the forces strong enough to provide protection from leaching, and also weak enough to enable absorption through the plant root. This ability becomes more pronounced if the degree of dispersity is higher, i.e. if particles have smaller diameters. Total of 435 soil samples were collected from the surface horizon in 2011, for the purpose of soil fertility control in Vojvodina and prevention of its possible degradation in broader terms. This paper presents a part of study through selected representative soil samples, related to the research results of mechanical composition, basic chemical properties, and cation-exchange capacity in the most frequent types of soils in North Bačka and Banat (chernozem, fluvisol, semiglay, humoglay, solonchak, solonetz, due to the fact that soil fertility and its ecological function in environment protection largely depend on the studied properties. The average content of clay was 25.26%, ranging from 5.76 to 49.44%, the average content of humus was 3.10%, ranging between 1.02 and 4.30%, while the average value of CEC was 27.30 cmol/kg, ranging between 12.03 and 46.06 cmol/kg. Soils with higher content of clay and humus have greater cation-exchange capacity. According to the established average values of CEC in cmol/kg, the order of soil types is as follows: solonetz (40.06, semiglay (31.98, humoglay (30.98, solonchak (26.62, chernozem (22.72, and fluvisol (22.40. Research results have shown that cation-exchange capacity depends on clay fraction and humus content. Higher correlation coefficient between CEC and clay, compared to CEC and humus, indicates that clay content compared to humus content has greater effect on cation-exchange capacity.

  20. Mathematical Modeling of Cation Contamination in a Proton-exchange Membrane

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Adam; Delacourt, Charles


    Transport phenomena in an ion-exchange membrane containing both H+ and K+ are described using multicomponent diffusion equations (Stefan-Maxwell). A model is developed for transport through a Nafion 112 membrane in a hydrogen-pump setup. The model results are analyzed to quantify the impact of cation contamination on cell potential. It is shown that limiting current densities can result due to a decrease in proton concentration caused by the build-up of contaminant ions. An average cation concentration of 30 to 40 percent is required for appreciable effects to be noticed under typical steady-state operating conditions.

  1. Enhanced desorption of Cs from clays by a polymeric cation-exchange agent

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chan Woo, E-mail: [Decontamination & Decommissioning Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon (Korea, Republic of); Kim, Bo Hyun [Decontamination & Decommissioning Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon (Korea, Republic of); Department of Chemical Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Yang, Hee-Man; Seo, Bum-Kyoung [Decontamination & Decommissioning Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Kune-Woo, E-mail: [Decontamination & Decommissioning Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon (Korea, Republic of)


    Highlights: • A cationic polyelectrolyte has excellent ability to desorb Cs bound strongly to clay. • The polycation desorbed significantly more Cs from the clay than did single cations. • Additional NH{sub 4}{sup +} treatment following the polycation treatment enhanced desorption of Cs. • The reaction yielded efficient desorption (95%) of an extremely low concentration of Cs-137 in the clay. - Abstract: We report on a new approach to increase the removal of cesium from contaminated clays based on the intercalation of a cationic polyelectrolyte into the clay interlayers. A highly charged cationic polyelectrolyte, polyethyleneimine (PEI), was shown to intercalate into the negatively charged interlayers and readily replaced Cs ions adsorbed on the interlayers of montmorillonite. The polycation desorbed significantly more Cs strongly bound to the clay than did single cations. Moreover, additional NH{sub 4}{sup +} treatment following the PEI treatment enhanced desorption of Cs ions that were less accessible by the bulky polyelectrolyte. This synergistic effect of PEI with NH{sub 4}{sup +} yielded efficient desorption (95%) of an extremely low concentration of radioactive {sup 137}Cs in the clay, which is very difficult to remove by simple cation-exchange methods due to the increased stability of the binding of Cs to the clay at low Cs concentrations.

  2. Strong cation-exchange chromatography of proteins on a sulfoalkylated monolithic cryogel. (United States)

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


    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. Copyright © 2015 Elsevier B.V. All rights reserved.

  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)


    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. Dehydration enthalpy of alkali-cations-exchanged montmorillonite from thermogravimetric analysis. (United States)

    Kharroubi, M; Balme, S; Henn, F; Giuntini, J C; Belarbi, H; Haouzi, A


    Dehydration of a series of homoionic alkali-exchanged montmorillonites is studied at different treatment temperatures by means of thermogravimetric analysis. More specifically, we investigate the last stages of dehydration when the number of adsorbed water molecules corresponds, at maximum, to a monolayer. Weight losses are measured at several constant temperatures as a function of time. Application of Van't Hoff's law yields the dehydration enthalpy. Trends and data similar to those reported from other experimental conditions are found. Comparison with X-ray data and with the dissociation enthalpy of alkali cation/water complexes shows that dehydration of weakly hydrated homoionic alkali montmorillonites results from the competition between opposite energy contributions due to (i) the cation solvation, (ii) the hydration of the silicate interlayer surface, and (iii) the structural swelling. So, depending on the balance between these various energy contributions, different behaviors are observed according to the nature of the alkali cations.

  5. Recent progress and applications of ion-exclusion/ion-exchange chromatography for simultaneous determination of inorganic anions and cations. (United States)

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


    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.

  6. Concentration of ions Co(II), Ni(II) at the Tokem-250 carboxylic cation exchange for catalysts development (United States)

    Zharkova, Valentina; Bobkova, Ludmila; Brichkov, Anton; Kozik, Vladimir


    Sorption and catalytic properties of the cation exchanger are investigated. It was found that the Tokem-250 has a wide operating range of pH. The value of the effective ionization constant of the functional groups of the cation exchanger (pKa) is 6.59. The Tokem-250 cation exchanger exhibits selectivity to Ni2+ ions to Co2+ (D˜103). This is probably due to the stability of ion-exchange complexes detected by the method of diffuse reflectance electron spectroscopy (ESDD). According to these data, for Co2+ ions, in contrast to Ni2+, tetragonal distortion of octahedral coordination is characteristic, which has a positive effect on the stability of complexes with Co2+. To obtain spherical catalysts on the basis of Tokem-250, cobalt-containing samples of cation exchanger were used. The developed spherical materials have catalytic activity in the reactions of deep and partial oxidation of n-heptane.

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

    KAUST Repository

    Han, Sanyang


    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.

  8. Solvent Extraction of Tungsten(VI) from Moderate Hydrochloric Acid Solutions with LIX 63

    Energy Technology Data Exchange (ETDEWEB)

    Truong, Hoai Thanh; Lee, Man Seung [Mokpo National University, Jeollanamdo (Korea, Republic of); Kim, Yong Hwan [Incheon Technology Service Centre, Incheon (Korea, Republic of)


    The solvent extraction of tungsten(VI) from hydrochloric acid solutions using 5,8-diethyl-7-hydroxydodecan-6-one oxime (LIX 63) was analyzed in solutions having an initial pH range from 2 to 5, by varying the concentration of metal and extractant. In our experimental range, the cationic exchange reaction as well as the solvation reaction occurred simultaneously. The cation exchange reaction was identified by applying a slope analysis method to the extraction data. The existence of cationic tungsten(VI) species was confirmed by ion exchange experiments with Diphonix resin at pH 3. Further study is needed to identify the nature of this tungsten cationic species.

  9. Effects of Cationic Pendant Groups on Ionic Conductivity for Anion Exchange Membranes: Structure Conductivity Relationships (United States)

    Kim, Sojeong; Choi, Soo-Hyung; Lee, Won Bo

    Anion exchange membranes(AEMs) have been widely studied due to their various applications, especially for Fuel cells. Previous proton exchange membranes(PEMs), such as Nafions® have better conductivity than AEMs so far. However, technical limitations such as slow electrode kinetics, carbon monoxide (CO) poisoning of metal catalysts, high methanol crossover and high cost of Pt-based catalyst detered further usages. AEMs have advantages to supplement its drawbacks. AEMs are environmentally friendly and cost-efficient. Based on the well-defined block copolymer, self-assembled morphology is expected to have some relationship with its ionic conductivity. Recently AEMs based on various cations, including ammonium, phosphonium, guanidinium, imidazolium, metal cation, and benzimidazolium cations have been developed and extensively studied with the aim to prepare high- performance AEMs. But more fundamental approach, such as relationships between nanostructure and conductivity is needed. We use well-defined block copolymer Poly(styrene-block-isoprene) as a backbone which is synthesized by anionic polymerization. Then we graft various cationic functional groups and analysis the relation between morphology and conductivity. Theoretical and computational soft matter lab.

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


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


    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...

  11. The Role of Cation/Proton Exchanger NHE9 in Synaptic Transmission & Autism


    Ullman, Julia Collier


    Autism spectrum disorders (ASD) are neurodevelopmental syndromes that affect an estimated 1.5 million people in the United States alone. While ASDs arising from single gene mutations are rare, the study of these conditions provides a powerful and effective approach toward understanding the molecular basis for ASD as well as normal social behaviors. Recently, the cation/hydrogen exchanger Nhe9 has surfaced as a locus for inherited autism, with mutations confirmed to abolish expression. In addi...

  12. Evaluation of the field-scale cation exchange capacity of Hanford sediments

    Energy Technology Data Exchange (ETDEWEB)

    Steefel, C.I.


    Three-dimensional simulations of unsaturated flow, transport, and multi-component, multi-site cation exchange in the vadose zone were used to analyze the migration of a plume resulting from a leak of the SX-115 tank at the Hanford site, USA. The match within about 0.5 meters of the positions of retarded sodium and potassium fronts suggests that the laboratory-derived parameters may be used in field-scale simulations of radionuclide migration at the Hanford site.

  13. Preparative separation of monoclonal antibody aggregates by cation-exchange laterally-fed membrane chromatography. (United States)

    Madadkar, Pedram; Sadavarte, Rahul; Butler, Michael; Durocher, Yves; Ghosh, Raja


    Cation exchange (CEX) chromatography is widely used for large-scale separation of monoclonal antibody (mAb) aggregates. The aggregates bind more strongly to CEX media and hence elute after the monomeric mAb in a salt gradient. However, monomer-aggregate resolution that is typically obtained is poor, which results in low product recovery. In the current study we address this challenge through the use of cation-exchange laterally-fed membrane chromatography (LFMC). Three different LFMC devices, each containing a bed of strong cation-exchange (S) membranes were used for preparative-scale removal of mAb aggregates. Trastuzumab (IgG1) biosimilar derived from human embryonic kidney 293 (293) cells was used as the primary model mAb in our study. The other mAbs investigated were Chinese hamster ovary (CHO) cell line derived Alemtuzumab (Campath-1H) and a heavy chain chimeric mAb EG2-hFc. In each of these case-studies, aggregates were well-resolved from the respective monomer. The separated and collected monomer and aggregate fractions were analyzed using techniques such as hydrophobic interaction membrane chromatography (HIMC), native polyacrylamide gel electrophoresis (or PAGE), and size-exclusion high-performance liquid chromatography (SE-HPLC). The high efficiency of separation obtained in each case was due to a combination of the small membrane pore size (3-5μm), and the use of LFMC technology, which has been shown to be suitable for high-resolution, multi-component protein separations. Also, the LFMC based separation processes reported in this study were more than an order of magnitude faster than equivalent resin-based, cation exchange chromatography. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Solubility and cation exchange in phosphate rock and saturated clinoptilolite mixtures (United States)

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


    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.

  15. Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Exchangeable Cation Species of Zeolites

    Directory of Open Access Journals (Sweden)

    Moses Wazingwa Munthali


    Full Text Available The saturation of negative charges of zeolites by specific cations to modify their physicochemical and catalytic properties has broadened the applications of zeolites. The adsorption behavior of H+ to Li+, Na+, K+, Rb+ and Cs+-saturated Linde-type A, Na-P1, mordenite, X type and Y type zeolites was evaluated at different pH-pM, where pH-pM is equal to log {(M+/(H+} and M+ represents either Li+, Na+, K+, Rb+, or Cs+. In all cases, with decreasing pH-pM, the amounts of alkali metal retention decreased due to the adsorption of H+ via cation exchange reaction. The adsorption selectivity of H+ into the zeolites had a negative correlation with the Si/Al ratio of the zeolites. In each zeolite species, Cs+-saturated zeolite showed the lowest H+ selectivity, and this suggested that Cs+ had the strongest adsorption energy in the alkali metal cations. The adsorption of H+ was strongly affected by diameter and hydration energy of the alkali metal cations, and was also affected by the framework type and Si/Al ratio of the zeolites. The adsorption of H+ into zeolites decreases the amount of cation retention other than with H+ and may cause the elution of Si and Al into aqueous solutions.

  16. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange (United States)

    Binetti, Enrico; Striccoli, Marinella; Sibillano, Teresa; Giannini, Cinzia; Brescia, Rosaria; Falqui, Andrea; Comparelli, Roberto; Corricelli, Michela; Tommasi, Raffaele; Agostiano, Angela; Curri, M. Lucia


    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.

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

    KAUST Repository

    Binetti, Enrico


    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.

  18. Study of cation-exchange capacity of soil near fluorspar mining with special reference to Kadipani mine (Gujarat, India). (United States)

    Pradhan, Alka; Deshmukh, Jitendra P


    One of the important functions of soil is exchange of cations, whereby essential trace metals are made available to plants as nutrients. Both minerals and organics fractions of soil exchange the cations. Clay minerals exchange cation because of the presence of negatively charged sites on the mineral while organic materials exchange cations by means of their carboxylate groups and other basic functional groups. Cation exchange in soil provides trace metal nutrients to plant. The metal ions are taken up by the roots while H+ is exchanged for the metal ions. Therefore, the measurement of Cation Exchange Capacity (CEC) of soil is important and this becomes more significant when the mining activity is carried out in the surrounding environment as mining activity may adversely impact the soil texture and organic matter content and sometimes changes the pH which is the main regulator of CEC in soil. The studies related to the assessment of CEC of soil were carried out. 14 soil samples, including one sample of mine site, were collected during summer season from different villages within 10 km radius from the mine site. These samples were then analyzed. The efforts were made to establish the CEC of soil quality of Kadipani, Distt. Vadodara, Gujarat, India. This study is useful for making the decisions regarding the environmental measures required for mining activity.

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

    NARCIS (Netherlands)

    Chen, Y.|info:eu-repo/dai/nl/322994179; Droge, S.T.J.|info:eu-repo/dai/nl/304834017; Hermens, J.L.M.|info:eu-repo/dai/nl/069681384


    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

  20. Strain effects in the common-cation II-VI heterostructures: case of ZnS/ZnSe superlattices

    CERN Document Server

    Tit, N


    The electronic band-structures of the strained-layer ZnS/ZnSe (001) superlattices (SLs) have been investigated using the sp sup 3 s* tight-binding method, which includes the strain and spin-orbit effects. The SL band-structures are studied versus the biaxial strain, layer thickness, and band offsets. The results suggest that the common-cation II-VI heterojunction exhibit a vanishingly small conduction-band offset (CBO). It is shown that the SL valence-band top state is always a heavy-hole localized within ZnSe slabs; whereas the conduction-band edge state (electron) is sensitive to the biaxial strain (or VBO). To assess the strain effects, we considered three differently strained SLs corresponding to the three substrates: (i) ZnSe; (ii) ZnS sub 0 sub . sub 5 Se sub 0 sub . sub 5; and (iii) ZnS. The results show that all the studied SLs are of type-I except those strained to ZnS (case iii), that may exhibit type-I to type-II transition. One striking result obtained here is the existence of a critical VBO (V su...

  1. Simultaneous determination of chromium(III) and chromium(VI) in aqueous solutions by ion chromatography and chemiluminescence detection

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Jøns, O; Nielsen, B


    A method for the simultaneous determination of chromium(iii) and chromium(vi) in a flow system based on chemiluminescence was developed. A Dionex cation-exchange guard column was used to separate chromium(iii) from chromium(vi), and chromium(vi) was reduced by potassium sulfite, whereupon both...

  2. A solid-state cation exchange reaction to form multiple metal oxide heterostructure nanowires. (United States)

    Chen, Y H; Huang, C W; Yeh, P H; Chen, J Y; Lin, T Y; Chang, C F; Wu, W W


    Metal oxide nanostructures have been investigated extensively due to their wide range of physical properties; zinc oxide is one of the most promising materials. It exhibits fascinating functional properties and various types of morphologies. In particular, ZnO heterostructures have attracted great attention because their performance can be modified and further improved by the addition of other materials. In this study, we successfully transformed ZnO nanowires (NWs) into multiple ZnO/Al 2 O 3 heterostructure NWs via a solid-state cation exchange reaction. The experiment was carried out in situ via an ultrahigh vacuum transmission electron microscope (UHV-TEM), which was equipped with a video recorder. Moreover, we analyzed the structure and composition of the heterostructure NWs by Cs-corrected STEM equipped with EDS. Based on these experimental results, we inferred a cation exchange reaction ion path model. Additionally, we investigated the defects that appeared after the cation reaction, which resulted from the remaining zinc ions. These multiple heterostructure ZnO/Al 2 O 3 NWs exhibited excellent UV sensing sensitivity and efficiency.


    Directory of Open Access Journals (Sweden)

    Marija Tomasic


    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.

  4. Comparison of reversed-phase/cation-exchange/anion-exchange trimodal stationary phases and their use in active pharmaceutical ingredient and counterion determinations. (United States)

    Liu, Xiaodong; Pohl, Christopher A


    This study involved three commercial reversed-phase (RP)/anion-exchange (AEX)/cation-exchange (CEX) trimodal columns, namely Acclaim Trinity P1 (Thermo Fisher Scientific), Obelisc R (SIELC Technologies) and Scherzo SM-C18 (Imtakt). Their chromatographic properties were compared in details with respect to hydrophobicity, anion-exchange capacity, cation-exchange capacity, and selectivity, by studying retention behavior dependency on organic solvent, buffer concentration and pH. It was found that their remarkably different column chemistries resulted in distinctive chromatography properties. Trinity P1 exhibited strong anion-exchange and cation-exchange interactions but low RP retention while Scherzo SM-C18 showed strong reversed-phase retention with little cation-exchange and anion-exchange capacities. For Obelisc R, its reversed-phase capacity was weaker than Scherzo SM-C18 but slightly higher than Trinity P1, and its ion-exchange retentions were between Trinity P1 and Scherzo SM-C18. In addition, their difference in selectivity was demonstrated by examples of determining the active pharmaceutical ingredient (API) and counterion of drug products. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Amino-functionalized alkaline clay with cationic star-shaped polymer as adsorbents for removal of Cr(VI) in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Yuanfeng, E-mail: [Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Cai, Pingxiong [Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Farmahini-Farahani, Madjid [Department of Chemical Engineering, University of New Brunswick, Fredericton, NB, E3B 5A3 (Canada); Li, Yiduo [Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Hou, Xiaobang [School of Environmental Sci & Eng., North China Electric Power University, Baoding 071003 (China); Xiao, Huining, E-mail: [Department of Chemical Engineering, University of New Brunswick, Fredericton, NB, E3B 5A3 (Canada)


    Highlights: • Four-arm cationic star-shaped copolymers were prepared via Atom Transfer Radical Polymerization (ATRP) with pentaerythritol. • Alkaline clay (AC) was immobilized with cationic star polymer (CSP). • CSP-immobilized AC was first used for Cr(VI) removal. • The adsorbent has a higher adsorption capacity than those reported elsewhere. - Abstract: Pentaerythritol (PER) was esterified with 2-bromoisobutyryl bromide to synthesize a four-arm initiator 4Br-PER for atom transfer radical polymerization (ATRP). Star-shaped copolymers (P(AM-co-DMAEMA){sub 4}, CSP) were prepared via ATRP using dimethyl aminoethyl methacrylate (DMAEMA) and acrylamide (AM) as comonomers, while Br-PER and CuBr/2,2′-bipyridine (BPY) as the initiator and the catalyst, respectively. The resulting four-arm initiator and star-shaped polymer (CSP) were characterized with FT-IR, {sup 1}H NMR and Ubbelohde viscometry. Alkaline clay (AC) was immobilized with CSPs to yield amino groups, and the cationic star polymer-immobilized alkaline clay (CSP-AC) was applied to remove Cr(VI) from the aqueous solution in batch experiments. Various influencing factors, including pH, contact time and immobilization amount of CSP on adsorption capacity of CSP-AC for Cr(VI) were also investigated. The results demonstrated that Cr(VI) adsorption was highly pH dependent. The optimized pH value was 4.0. The adsorption isotherms of the adsorbent fit the Langmuir model well, with the maximum adsorption capacity of 137.9 mg/g at 30 °C. The material should be a promising adsorbent for Cr(VI) removal, with the advantages of high adsorption capacity.

  6. Synthesis, characterization and applications of a new cation exchanger tamarind sulphonic acid (TSA) resin. (United States)

    Singh, A V; Sharma, Naresh Kumar; Rathore, Abhay S


    A new composite cation exchanger, tamarind sulphonic acid (TSA) resin has been synthesized. The chemically modified TSA ion exchange resin has been used for the removal and preconcentration of Zn2+, Cd2+, Fe2+, Co2+ and Cu2+ ions in aqueous solution and effluent from the Laxmi steel plant in Jodhpur, India. This type of composite represents a new class of hybrid ion exchangers with good ion exchange capacity, stability, reproducibility and selectivity for toxic metal ions found in effluent from the steel industry. The characterization of the resin was carried out by determining the ion-exchange capacity, elemental analysis, pH titration, Fourier transform infrared spectra and thermal analysis. The distribution coefficients (K(d)) of toxic metal ions were determined in a reference aqueous solution and the steel plant effluent at different pH values; the absorbency of different metal ions on the TSA resin was studied for up to 10 cycles. The adsorption of different metal ions on TSA resin follows the order: Co2+ > Cu2+ > Zn2+ > Fe2+ > Cd2+. The ion exchange capacity of TSA resin is 2.87%.

  7. Multidimensional separation of tryptic peptides from human serum proteins using reversed-phase, strong cation exchange, weak anion exchange, and fused-core fluorinated stationary phases

    NARCIS (Netherlands)

    Boichenko, Alexander P.; Govorukhina, Natalia; van der Zee, Ate G. J.; Bischoff, Rainer


    Proteome profiling of crude serum is a challenging task due to the wide dynamic range of protein concentrations and the presence of high-abundance proteins, which cover >90% of the total protein mass in serum. Peptide fractionation on strong cation exchange, weak anion exchange in the electrostatic

  8. Activity of some disiloxanes toward the cation exchange resin-catalyst in the siloxane equilibration reaction

    Directory of Open Access Journals (Sweden)



    Full Text Available The relative activities of four disiloxanes toward the cation exchange resin, which was used as an equilibration catalyst, were determined in such a way that the equilibrium initially present in an arbitrary chosen equilibrate was disturbed by adding the respective disiloxanes to it, and then by recording the viscosity of the equilibrating mixtures as a function of reaction time. As a result, a set of different viscosity-reaction time relationships was obtained, which implies different activities of disiloxanes toward the catalyst. In this way the following decreasing order of acitivites was established: 1,3-tetramethyldisiloxane > 1,3-divinyltetramethyldisiloxane > hexamethyldisiloxane > 1,3-bis(3-carboxypropyltetramethyldisiloxane.

  9. Kinetics of transesterification of methyl acetate and n-octanol catalyzed by cation exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yong; Gao, Li; Li, Xiying; Mao, Liqun [Henan University, Kaifeng (China); Wei, Min [Henan University of Technology, Zhengzhou (China)


    The transesterification kinetics of methyl acetate with n-octanol to octyl acetate and methanol were studied using Amberlyst 15 as catalyst in a batch stirred reactor. The influence of the agitation speed, particle size, temperature, catalyst loading, and initial reactants molar ratio was investigated in detail. A pseudo-homogeneous (PH) kinetic model was applied to correlate the experimental data in the temperature range of 313.15 K to 328.15 K. The estimated kinetic parameters made the calculated results in good agreement with the experimental data. A kinetic model describing the transesterification reaction catalyzed by cation exchange resins was developed.

  10. Dual transport properties of anion exchanger 1: the same transmembrane segment is involved in anion exchange and in a cation leak. (United States)

    Barneaud-Rocca, Damien; Borgese, Franck; Guizouarn, Hélène


    Previous results suggested that specific point mutations in human anion exchanger 1 (AE1) convert the electroneutral anion exchanger into a monovalent cation conductance. In the present study, the transport site for anion exchange and for the cation leak has been studied by cysteine scanning mutagenesis and sulfhydryl reagent chemistry. Moreover, the role of some highly conserved amino acids within members of the SLC4 family to which AE1 belongs has been assessed in AE1 transport properties. The results suggest that the same transport site within the AE1 spanning domain is involved in anion exchange or in cation transport. A functioning mechanism for this transport site is proposed according to transport properties of the different studied point mutations of AE1.

  11. 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


    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+....

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

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus


    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...... (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...... of the new PTFs, thus a simple measure of soil water content at an arbitrary relative humidity can provide reasonably accurate CEC estimates for large scale studies....

  13. Hexavalent chromium [Cr(VI)] removal by the electrochemical ion-exchange process. (United States)

    Dharnaik, Amit Shivputra; Ghosh, Pranab Kumar


    In the present investigation, the performance of a laboratory-scale plate and frame-type electrochemical ion-exchange (EIX) cell on removal ofhexavalent chromium from synthetic wastewater containing 5 mg/l of Cr(VI) was evaluated under varying applied voltages. Ruthenium dioxide-coated titanium plate (RuO2/Ti) was used as anode and stainless steel plates as cathode. The EIX cell was run at different hydraulic retention time (HRT). Before using in the electrochemical cell, the capacity of ion-exchange resin was evaluated through kinetic and isotherm equilibrium tests in batch mode. The batch kinetic study result showed that the equilibrium time for effective ion exchange with resin is 2 h. The isotherm equilibrium data fit well to both Freundlich and Langmuir isotherms. Maximum capacity (qm) of resin calculated from Langmuir isotherm was 71.42 mg/g. Up to 99% of chromium removal was noticed in the EIX cell containing fresh resin at applied voltages of 10 V and higher. Migration of chromium ion to anode chamber was not noticed while performing the experiment with fresh resin. As high as 50% removal of chromium was observed from the middle chamber containing exhausted resin at an applied voltage of 25 V when the influent flow rate was maintained at 45 min of HRT. The performance of the reactor was increased to 72% when the influent flow rate was decreased to maintain at 90 min of HRT. Build-up of chromium in the anode chamber took place when exhausted resin was used in the process.

  14. Extraction and derivatization of chemical weapons convention relevant aminoalcohols on magnetic cation-exchange resins. (United States)

    Singh, Varoon; Garg, Prabhat; Chinthakindi, Sridhar; Tak, Vijay; Dubey, Devendra Kumar


    Analysis and identification of nitrogen containing aminoalcohols is an integral part of the verification analysis of chemical weapons convention (CWC). This study was aimed to develop extraction and derivatization of aminoalcohols of CWC relevance by using magnetic dispersive solid-phase extraction (MDSPE) in combination with on-resin derivatization (ORD). For this purpose, sulfonated magnetic cation-exchange resins (SMRs) were prepared using magnetite nanoparticles as core, styrene and divinylbenzene as polymer coat and sulfonic acid as acidic cation exchanger. SMRs were successfully employed as extractant for targeted basic analytes. Adsorbed analytes were derivatized with hexamethyldisilazane (HMDS) on the surface of extractant. Derivatized (silylated) compounds were analyzed by GC-MS in SIM and full scan mode. The linearity of the method ranged from 5 to 200ngmL(-1). The LOD and LOQ ranged from 2 to 6ngmL(-1) and 5 to 19ngmL(-1) respectively. The relative standard deviation for intra-day repeatability and inter-day intermediate precision ranged from 5.1% to 6.6% and 0.2% to 7.6% respectively. Recoveries of analytes from spiked water samples from different sources varied from 28.4% to 89.3%. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Esterification of palm fatty acid distillate with epychlorohydrin using cation exchange resin catalyst (United States)

    Budhijanto, Budhijanto; Subagyo, Albertus F. P. H.


    Palm Fatty Acid Distillate (PFAD) is one of the wastes from the conversion of crude palm oil (CPO) into cooking oil. The PFAD is currently only utilized as the raw material for low grade soap and biofuel. To improve the economic value of PFAD, it was converted into monoglyceride by esterification process. Furthermore, the monoglyceride could be polymerized to form alkyd resin, which is a commodity of increasing importance. This study aimed to propose a kinetics model for esterification of PFAD with epichlorohydrin using cation exchange resin catalyst. The reaction was the first step from a series of reactions to produce the monoglyceride. In this study, the reaction between PFAD and epichlorohydirne was run in a stirred batch reactor. The stirrer was operated at a constant speed of 400 RPM. The reaction was carried out for 180 minutes on varied temperatures of 60°C, 70°C, 80°C, dan 90°C. Cation exchange resin was applied as solid catalysts. Analysis was conducted periodically by measuring the acid number of the samples, which was further used to calculate PFAD conversion. The data were used to determine the rate constants and the equilibrium constants of the kinetics model. The kinetics constants implied that the reaction was reversible and controlled by the intrinsic surface reaction. Despite the complication of the heterogeneous nature of the reaction, the kinetics data well fitted the elementary rate law. The effect of temperature on the equilibrium constants indicated that the reaction is exothermic.

  16. Morphologically Aligned Cation-Exchange Membranes by a Pulsed Electric Field for Reverse Electrodialysis. (United States)

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


    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.

  17. Effect of ionophores on the rate of intramolecular cation exchange in durosemiquinone ion pairs (United States)

    Eastman, M. P.; Bruno, G. V.; Mcguyer, C. A.; Gutierrez, A. R.; Shannon, J. M.


    The effects of the ionophores 15-crown-5 (15C5), 18-crown-6 (18C6), dibenzo-18-crown-6 (DBC) and cryptand 222 (C222) on intramolecular cation exchange in ion pairs of the sodium salt of the durosemiquinone anion in benzene solution are investigated. Electron paramagnetic resonance spectra of the 18C6 and 15C5 complexes with durosemiquinone reduced by contact with a sodium mirror show an alternating line width which indicates that the sodium ion is being exchanged between equivalent sites near the oxygens of the semiquinone with activation energies of 8.7 and 6.0 kcal/mole and Arrhenius preexponential factors of 9 x 10 to the 12th/sec and 10 to the 12th/sec, respectively. Spectra obtained for the DBC complexes show no evidence of exchange, while those of C222 indicate rapid exchange. It is also noted that the hyperfine splitting constants measured do not change over the 50-K temperature interval studied.

  18. Use of Ionic liquids as additives in ion exchange chromatography for the analysis of cations. (United States)

    Di, Huawei; Zhu, Xiashi


    The behavior of acids (citric acid, nitric acid, oxalic acid, tartaric acid) as a mobile phase and imidazolium ionic liquids (the bromides, tetrafluoroborates and hexafluorophosphates of 1-ethyl, 1-butyl, and 1-hexyl-3-methylimidazolium) as additives in ion exchange chromatography for cations (Na+ , K+ , Mg2+ , Ca2+ ) separation were studied. The results showed that nitric acid and 1-hexyl-3-methyl-imidazolium hexafluorophosphate offered the most interesting features in the separation of cations, such as lower retention time and better resolution. The selected optimal conditions were achieved by adding 0.10 mM 1-hexyl-3-methyl-imidazolium hexafluorophosphate in 4.0 mM HNO3 mobile phase for the separation of four cations with the flow rate of 0.9 mL/min at room temperature (25°C). The linear regression equations of Na+ , K+ , Mg2+ , Ca2+ were S = 4.4763c + 0.0209, S = 3.8903c - 0.0087, S = 6.3974c - 0.0173, and S = 7.601c - 0.0339 and the limits of detection of Na+ , K+ , Mg2+ , Ca2+ were 0.296, 4.98, 0.0970, and 1.22 μg/L, respectively. In this work, four cations in samples were successfully detected. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    KAUST Repository

    Casu, Alberto


    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.

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

    KAUST Repository

    Chen, Yifei


    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.

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

    Directory of Open Access Journals (Sweden)

    Stefan L.


    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.

  2. Mechanism of improved antibody aggregate separation in polyethylene glycol-modulated cation exchange chromatography. (United States)

    Kluters, Simon; Neumann, Sebastian; von Hirschheydt, Thomas; Grossmann, Adelbert; Schaubmar, Andreas; Frech, Christian


    Ion-exchange chromatography is used in biopharmaceutical downstream processes to reduce product-related impurity levels. Because protein aggregate levels can be considered as a critical quality attribute, the removal of aggregated protein species is of primary importance. The addition of polyethylene glycol (PEG) to the mobile phase in ion-exchange chromatography was found to significantly improve the chromatographic separation of monomers from aggregates. In this work, linear gradient elution experiments with monomeric and aggregated samples of a monoclonal antibody were performed on a strong cation exchange resin at different PEG concentrations to investigate the underlying effects responsible for the observed selectivity improvement. PEG is well known to be excluded from a surface layer volume around the protein and the stationary phase; thus, enhancing adsorption of the preferentially hydrated protein to the hydrated stationary phase. The exclusion volume depends on the accessible surface area of the protein leading to a stronger influence of PEG on larger protein species and thus an improved separation of monomer and aggregates. This hypothesis could be consolidated comparing the distribution equilibrium in PEG solution to that in water by calculating equilibrium constants and transfer free energies using the chromatographic data from the linear gradient elution experiments performed at different pH values. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. pH Transitions in ion-exchange systems: role in the development of a cation-exchange process for a recombinant protein. (United States)

    Ghose, Sanchayita; McNerney, Thomas M; Hubbard, Brian


    Unexpected transient changes in effluent pH can occur during ion-exchange chromatography. Such changes can occur even if a column that is equilibrated with a buffer receives another solution in the same buffer and of the same pH but of a different salt concentration. An attempt is made to understand the basis for this phenomenon and apply it to the process purification of a recombinant protein on a strong cation-exchange resin. Incomplete column equilibration was eliminated as a possible cause of these effects. Various buffering species and various salt ions were studied at different solution concentrations to investigate pH transitions on strong cation-exchange resins. A further comparison was made between cation-exchange resins with different backbone chemistries. On the basis of these studies, a mechanism is proposed for these phenomena based on competitive equilibria between ions from the buffer salts and H(+)/OH(-) ions. In addition to the equilibria between these ions and the functional groups on the resins, charged groups on the resin backbone were also found to contribute to transient pH changes. The results from this study were applied to the cation-exchange step for a recombinant protein that was sensitive to pH excursions to help maintain activity of the protein during the purification process.

  4. Strong Cation Exchange Chromatography in Analysis of Posttranslational Modifications: Innovations and Perspectives (United States)

    Edelmann, Mariola J.


    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. PMID:22174558

  5. Effect of cation exchange on the subsequent reactivity of lignite chars to steam. [108 references

    Energy Technology Data Exchange (ETDEWEB)

    Hippo, E. J.; Walker, Jr., P. L.


    The purpose of this investigation is to determine the role which cations in coal play in the subsequent reactivity of chars. It is hoped that this investigation will aid in an understanding of the catalytic nature of inorganic constituents in coal during its gasification. It was found that increased heat treatment temperature decreased reactivity. The decrease in reactivity was shown to be due, at least in part, to the changes in the nature of the cation with increased heat treatment temperature. Reactivity was found to be a linear function of the amount of Ca(++) exchange on the demineralized coal. The constant utilization factor over the wide range of loadings employed indicated that below 800/sup 0/C the calcium did not markedly sinter. Potassium, sodium, and calcium-containing chars were found to be much more reactive than the iron and magnesium-containing chars. However, the iron and magnesium containing chars were more reactive than chars produced from the demineralized coal. The iron char was highly active at first but the iron phase was quickly oxidized to a comparatively unreactive ..gamma..Fe/sub 2/O/sub 3/-Fe/sub 3/O/sub 4/ phase. The state of magnesium was found to be MgO. Sodium and calcium were equally active as catalysts but not as active as potassium.

  6. Reach-scale cation exchange controls on major ion chemistry of an Antarctic glacial meltwater stream (United States)

    Gooseff, Michael N.; McKnight, Diane M.; Runkel, Robert L.


    McMurdo dry valleys of Antarctica represent the largest of the ice-free areas on the Antarctic continent, containing glaciers, meltwater streams, and closed basin lakes. Previous geochemical studies of dry valley streams and lakes have addressed chemical weathering reactions of hyporheic substrate and geochemical evolution of dry valley surface waters. We examine cation transport and exchange reactions during a stream tracer experiment in a dry valley glacial meltwater stream. The injection solution was composed of dissolved Li+, Na+, K+, and Cl-. Chloride behaved conservatively in this stream, but Li+, Na+, and K+ were reactive to varying degrees. Mass balance analysis indicates that relative to Cl-, Li+ and K+ were taken up in downstream transport and Na+ was released. Simulations of conservative and reactive (first-order uptake or generation) solute transport were made with the OTIS (one-dimensional solute transport with inflow and storage) model. Among the four experimental reaches of Green Creek, solute transport simulations reveal that Li+ was removed from stream water in all four reaches, K+ was released in two reaches, taken up in one reach, and Na+ was released in all four reaches. Hyporheic sediments appear to be variable with uptake of Li+ in two reaches, uptake of K+ in one reach, release of K+ in two reaches, and uptake of Na+ in one reach. Mass balances of the conservative and reactive simulations show that from 1.05 to 2.19 moles of Li+ was adsorbed per reach, but less than 0.3 moles of K+ and less than 0.9 moles of Na+ were released per reach. This suggests that either (1) exchange of another ion which was not analyzed in this experiment or (2) that both ion exchange and sorption control inorganic solute transport. The elevated cation concentrations introduced during the experiment are typical of initial flows in each flow season, which flush accumulated dry salts from the streambed. We propose that the bed sediments (which compose the hyporheic

  7. Kinetics of Coloration in Photochromic Tungsten(VI) Oxide/Silicon Oxycarbide/Silica Hybrid Xerogel: Insight into Cation Self-diffusion Mechanisms. (United States)

    Adachi, Kenta; Tokushige, Masataka; Omata, Kaoru; Yamazaki, Suzuko; Iwadate, Yoshiaki


    Silicon oxycarbide/silica composites with well-dispersed tungsten(VI) oxide (WO3) nanoparticles were obtained as transparent hybrid xerogels via an acid-catalyzed sol-gel process (hydrolysis/condensation polymerization) of 3-(triethoxysilyl)propyl methacrylate (TESPMA) and tetraethoxysilane (TEOS). The self-diffusion mechanism of alkali-metal cations and the kinetics of the photochromic coloration process in the WO3/TESPMA/TEOS hybrid xerogel systems have been systematically investigated. Under continuous UV illumination, a gradual color change (colorless → blue) corresponding to the reduction of W(6+) into W(5+) states in WO3 nanoparticles can be confirmed from the WO3/TESPMA/TEOS hybrid xerogels containing alkali-metal sulfates, although no coloration of the hybrid xerogel without alkali-metal sulfate was observed. The coloration behavior depended exclusively on a variety of alkali-metal cations present in the hybrid xerogel system. Furthermore, a detailed analysis of the self-diffusion mechanism confirmed that the alkali-metal cations electrostatically interact with a layer of unreacted silanol groups on the TESPMA/TEOS matrix surface, and subsequently pass through the interconnected pore network of the hybrid xerogel. More interestingly, in the context of an Arrhenius analysis, we found a good coincidence between the activation energies for alkali-metal cation self-diffusion and UV-induced coloration in the WO3/TESPMA/TEOS hybrid xerogel system containing the corresponding alkali-metal sulfate. It is experimentally obvious that the photochromic properties are dominated by the diffusion process of alkali-metal cations in the WO3/TESPMA/TEOS hybrid xerogel system. Such hybrid materials with cation-controlled photochromic properties will show promising prospects in applications demanding energy-efficient "smart windows" and "smart glasses".

  8. Quantification of unsaturated-zone alteration and cation exchange in zeolitized tuffs at Yucca Mountain, Nevada, USA (United States)

    Vaniman, David T.; Chipera, Steve J.; Bish, David L.; Carey, J. William; Levy, Schön S.


    Zeolitized horizons in the unsaturated zone (UZ) at Yucca Mountain, Nevada, USA, are an important component in concepts for a high-level nuclear waste repository at this site. The use of combined quantitative X-ray diffraction and geochemical analysis allows measurement of the chemical changes that accompanied open-system zeolitization at Yucca Mountain. This approach also provides measures of the extent of chemical migration that has occurred in these horizons as a result of subsequent cation exchange. Mass-balance analysis of zeolitized horizons with extensive cation exchange (drill hole UZ-16) and with only minimal cation exchange (drill hole SD-9) shows that Al is essentially immobile. Although zeolitization occurred in an open system, the mass transfer of constituents other than water is relatively small in initial zeolitization, in contrast to the larger scales of cation exchange that can occur after zeolites have formed. Cation exchange in the clinoptilolite ± mordenite zeolitized horizons is seen in downward-diminishing concentration gradients of Ca, Mg, and Sr exchanged for Na and (to lesser extent) K. Comparison with data from drill hole SD-7, which has multiple zeolitized horizons above the water table, shows that the upper horizons accumulate Ca, Mg, and Sr to such an extent that transport of these elements to the deepest UZ zeolitized horizon can be blocked. Quantitative analysis of zeolite formation yields insight into processes that are implied from laboratory studies and modeling efforts but are otherwise unverified at the site. Such analysis also yields information not provided by or contradicted by some models of flow and transport. The results include the following: (1) evidence of effective downward flow through zeolitic horizons despite the low permeability of these horizons, (2) evidence that alkaline-earth elements accumulated by zeolites are mostly derived from eolian materials in surface soils, (3) validation of the very effective

  9. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells? (United States)

    Sljukić, Biljana; Morais, Ana L; Santos, Diogo M F; Sequeira, César A C


    Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC's performance. Cell polarization, power density, stability, and durability tests are used in the membranes' evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

  10. Pectin–Tin(IV molybdosilicate: An ecofriendly cationic exchanger and its potential for sorption of heavy metals from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Nimisha K. V


    Full Text Available A novel composite cation exchanger of biopolymer Pectin and Tin(IV molybdosilicate heteropoly acid salt were prepared by co-precipitation technique. Physico-chemical characterization of Pectin–Tin(IV molybdosilicate was performed using instrumental techniques such as FTIR, TG, XRD and SEM–EDS. Studies were carried out to investigate ion exchange capacity. pH titration carried out shows cationic nature and polyfunctionality of the exchanger. Distribution coefficients of various metal ions were done to explore the ion exchange behavior of cation exchanger. Distribution studies show that the material is highly selective for toxic heavy metal ions such as Cd2+, Cu2+, Al3+ etc. To investigate the environmental applicability of the exchanger some analytically important binary separations and selective separation of metal ions from industrial effluents were achieved. Kinetic and isotherm parameters were evaluated to predict the mechanism of sorption of heavy metal ions. Mass transfer analysis shows that internal particle diffusion and some degree of boundary layer control the sorption process.

  11. High-throughput protein purification under denaturating conditions by the use of cation exchange chromatography. (United States)

    Alm, Tove; Steen, Johanna; Ottosson, Jenny; Hober, Sophia


    A high-throughput protein purification strategy using the polycationic Z(basic) tag has been developed. In order for the strategy to be useful both for soluble and less soluble proteins, a denaturating agent, urea, was used in all purification steps. First, four target proteins were genetically fused to the purification tag, Z(basic). These protein constructs were purified by cation exchange chromatography and eluted using a salt gradient. From the data achieved, a purification strategy was planned including stepwise elution to enable parallel protein purification using a laboratory robot. A protocol that includes all steps, equilibration of the chromatography resin, load of sample, wash, and elution, all without any manual handling steps, was handled by the laboratory robot. The program allows automated purification giving milligram amounts of pure recombinant protein of up to 60 cell lysates. In this study 22 different protein constructs, with different characteristics regarding pI and solubility, were successfully purified by the laboratory robot. The data show that Z(basic) can be used as a general purification tag also under denaturating conditions. Moreover, the strategy enables purification of proteins with different pI and solubility using ion exchange chromatography (IEXC). The procedure is highly reproducible and allows for high protein yield and purity and is therefore a good complement to the commonly used His(6)-tag.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sleutels, Tom H.J.A.; Buisman, Cees J.N. [Sub-Department of Environmental Technology, Wageningen University, Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Wetsus, Centre of Excellence for Sustainable Water Technology, Agora 1, P.O. Box 1113, 8900 CC Leeuwarden (Netherlands); Hamelers, Hubertus V.M. [Sub-Department of Environmental Technology, Wageningen University, Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Rozendal, Rene A. [Advanced Water Management Centre (AWMC), The University of Queensland, Qld 4072 (Australia)


    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-electrochemical systems, based on potential losses and partial system resistances. Our study reconfirmed the large difference in performance between the AEM configuration (2.1 m{sup 3} H{sub 2} m{sup -3} d{sup -1}) and CEM configuration (0.4 m{sup 3} H{sub 2} m{sup -3} d{sup -1}) at 1 V. This better performance was caused mainly by the much lower internal resistance of the AEM configuration (192 m{omega} m{sup 2}) compared to the CEM configuration (435 m{omega} m{sup 2}). This lower internal resistance could be attributed to the lower transport resistance of ions through the AEM compared to the CEM caused by the properties of both membranes. By analyzing the changes in resistances the limitations in an MEC can be identified which can lead to improved cell design and higher hydrogen production rates. (author)

  13. Estimating Soil Cation Exchange Capacity from Soil Physical and Chemical Properties (United States)

    Bateni, S. M.; Emamgholizadeh, S.; Shahsavani, D.


    The soil Cation Exchange Capacity (CEC) is an important soil characteristic that has many applications in soil science and environmental studies. For example, CEC influences soil fertility by controlling the exchange of ions in the soil. Measurement of CEC is costly and difficult. Consequently, several studies attempted to obtain CEC from readily measurable soil physical and chemical properties such as soil pH, organic matter, soil texture, bulk density, and particle size distribution. These studies have often used multiple regression or artificial neural network models. Regression-based models cannot capture the intricate relationship between CEC and soil physical and chemical attributes and provide inaccurate CEC estimates. Although neural network models perform better than regression methods, they act like a black-box and cannot generate an explicit expression for retrieval of CEC from soil properties. In a departure with regression and neural network models, this study uses Genetic Expression Programming (GEP) and Multivariate Adaptive Regression Splines (MARS) to estimate CEC from easily measurable soil variables such as clay, pH, and OM. CEC estimates from GEP and MARS are compared with measurements at two field sites in Iran. Results show that GEP and MARS can estimate CEC accurately. Also, the MARS model performs slightly better than GEP. Finally, a sensitivity test indicates that organic matter and pH have respectively the least and the most significant impact on CEC.

  14. 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)


    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.

  15. Synthesis of granular zeolitic materials with high cation exchange capacity from agglomerated coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Roberto Juan; Susana Hernandez; Jose Manuel Andres; Carmen Ruiz [Instituto de Carboquimica (CSIC), Zaragoza (Spain)


    Fly ash from coal combustion is a potential source of pollution and there is continuous interest in its recycling by converting it into products such as zeolitic materials for use in retaining pollutants. In this paper, production of granular zeolitic material from a commercially-unusable fine-fraction of a lightweight aggregate (LA) building material made from coal fly ash agglomerated with lime, by conventional alkaline activation is described. NaP1 zeolite, K-F zeolite, K-Phillipsite and K-Chabazite were synthesised. The process was optimised by combining four reaction parameters (temperature, alkali concentration, solution/fly ash ratio and reaction time). Zeolitic materials with the highest zeolite yields and cation exchange capacities were selected for future application in environmental processes. End-product zeolitic materials maintain its granular form and this could favour their use in some particular applications for environmental waste treatment (e.g. ionic exchange in column) without any further transformation stages. 21 refs., 6 figs., 6 tabs.

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

    Directory of Open Access Journals (Sweden)

    Erik Ayala-Bribiesca


    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.

  17. Simultaneous isolation of lactoferrin and lactoperoxidase from bovine colostrum by SPEC 70 SLS cation exchange resin. (United States)

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


    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.

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

    Directory of Open Access Journals (Sweden)

    Mianbin Wu


    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.

  19. 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.


    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

  20. 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


    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

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

    NARCIS (Netherlands)

    Balster, J.H.; Krupenko, O.; Krupenko, O.; Punt, Ineke G.M.; Stamatialis, Dimitrios; Wessling, Matthias


    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

  2. 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


    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

  3. Improving pH gradient cation-exchange chromatography of monoclonal antibodies by controlling ionic strength. (United States)

    Zhang, Liangyi; Patapoff, Thomas; Farnan, Dell; Zhang, Boyan


    Analytical ion exchange chromatography (IEC) is widely used to profile the charge heterogeneity of therapeutic monoclonal antibodies (mAbs). Since conventional salt gradient IEC methods are product-specific and time-consuming to develop, a previously reported alternative pH gradient IEC (pH-IEC) method using a cation-exchange column has been shown to be a multiproduct charge sensitive separation method for mAbs with isoelectric points between 7.3 and 9.0. In the work presented here, we have extended the application of that pH-IEC method to also profile the charge heterogeneity of mAbs with extreme pI values (e.g. acidic with pI9). A key observation of our work is that for the buffer systems used by Farnan and Moreno, the ionic strength of the mobile phase containing multiple polyamine buffers is pH and concentration dependent, and the ionic strength decreases when the pH increases. For the mobile phase with high buffer concentration the ionic strength is high at low pH values, leading to the flow through of acidic mAbs on the cation-exchange column. The basic mAbs may not have an optimal elution profile as the relatively low ionic strength of the mobile phase reduces the resolution of pH-IEC. To modulate the ionic strength, we introduced a salt gradient in addition to the pH gradient. Studies were performed to optimize the buffer and salt concentrations simultaneously to improve the retention of low pI mAbs and the resolution of high pI mAbs. The optimized salt-mediated pH-IEC method was not only applicable to mAbs over a broader pI range from 6.2 to 9.4, but also offered better resolution for mAbs with pI values between 7.3 and 9.0 than the previously reported pH-IEC method. This salt-mediated pH-IEC method was demonstrated to be robust at various chromatography conditions and capable of assessing manufacturing consistency and monitoring degradation of mAbs. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Cationic Tungsten(VI) Penta-Methyl Complex: Synthesis, Characterization and its Application in Olefin Metathesis Reaction


    Dey Raju; Samantaray Manoja K.; Callens Emmanuel; Hamieh Ali; Emwas Abdul-Hamid M.; Abou-hamad Edy; Kavitake Santosh; Basset Jean-Marie


    Tungsten-hexa-methyl readily reacts with B(C6F5)3 in dichloromethane and generates the corresponding well-defined cationic tungsten-penta-methyl complex which was identified precisely by 1H NMR, 13C NMR, 1H-13C NMR correlation spectroscopy. Unlike WMe6, this cationic complex has low energy barrier to form tungsten carbene intermediate, which was further supported by the fact that WMe6 alone has no activity in olefin metathesis reaction whereas the cationic complex shows catalytic activity for...

  5. Cationic Tungsten(VI Penta-Methyl Complex: Synthesis, Characterization and its Application in Olefin Metathesis Reaction

    Directory of Open Access Journals (Sweden)

    Dey Raju


    Full Text Available Tungsten-hexa-methyl readily reacts with B(C6F53 in dichloromethane and generates the corresponding well-defined cationic tungsten-penta-methyl complex which was identified precisely by 1H NMR, 13C NMR, 1H-13C NMR correlation spectroscopy. Unlike WMe6, this cationic complex has low energy barrier to form tungsten carbene intermediate, which was further supported by the fact that WMe6 alone has no activity in olefin metathesis reaction whereas the cationic complex shows catalytic activity for self-metathesis of 1-octene.

  6. Cationic Tungsten(VI) Penta-Methyl Complex: Synthesis, Characterization and its Application in Olefin Metathesis Reaction

    KAUST Repository

    Dey, Raju


    Tungsten-hexa-methyl readily reacts with B(C6F5)3 in dichloromethane and generates the corresponding well-defined cationic tungsten-penta-methyl complex which was identified precisely by 1H NMR, 13C NMR, 1H-13C NMR correlation spectroscopy. Unlike WMe6, this cationic complex has low energy barrier to form tungsten carbene intermediate, which was further supported by the fact that WMe6 alone has no activity in olefin metathesis reaction whereas the cationic complex shows catalytic activity for self-metathesis of 1-octene.

  7. Characterization, kinetic, and isotherm data for Cr (VI removal from aqueous solution by Populus alba biochar modified by a cationic surfactant

    Directory of Open Access Journals (Sweden)

    Maryam Shahverdi


    Full Text Available Populus alba is fast and auto- growing tree which profoundly accessible in around the world. The usage of the wastes of this tree would be admirable from environmental and solid waste management point of view. Thus, herein, this data set presents a facile method for providing an adsorbent from wastes of P. alba tree. The prepared adsorbent was modified by the cationic surfactant of (C16H33N(CH33Br and applied to remove Cr (VI from aqueous solution. The characterization data of the modified adsorbent were analyzed using FTIR and SEM methods. The information regarding kinetics, isotherms, and thermodynamics of chromium ions adsorption were listed. The data implied that the maximum adsorption capacity of adsorbent to uptake Cr (VI from aqueous solution was obtained 52.63 mg/g. The acquired data indicated that the adsorption of Cr (VI by the adsorbent prepared from P. alba is an promising technique for treating Cr-bearing wastewaters.

  8. Characterization, kinetic, and isotherm data for Cr (VI) removal from aqueous solution by Populus alba biochar modified by a cationic surfactant. (United States)

    Shahverdi, Maryam; Kouhgardi, Esmaeil; Ramavandi, Bahman


    Populus alba is fast and auto- growing tree which profoundly accessible in around the world. The usage of the wastes of this tree would be admirable from environmental and solid waste management point of view. Thus, herein, this data set presents a facile method for providing an adsorbent from wastes of P. alba tree. The prepared adsorbent was modified by the cationic surfactant of (C16H33)N(CH3)3Br and applied to remove Cr (VI) from aqueous solution. The characterization data of the modified adsorbent were analyzed using FTIR and SEM methods. The information regarding kinetics, isotherms, and thermodynamics of chromium ions adsorption were listed. The data implied that the maximum adsorption capacity of adsorbent to uptake Cr (VI) from aqueous solution was obtained 52.63 mg/g. The acquired data indicated that the adsorption of Cr (VI) by the adsorbent prepared from P. alba is an promising technique for treating Cr-bearing wastewaters.

  9. Concentration dependence of cation-induced electrohydrodynamic flow passing through an anion exchange membrane (United States)

    Yano, Ayako; Shirai, Hiroki; Imoto, Moino; Doi, Kentaro; Kawano, Satoyuki


    Electrohydrodynamic (EHD) flow is a type of liquid flow driven by an external electric force. In electrolyte solutions, anions and cations usually interact with each other to maintain electroneutrality. Under such a condition, it is difficult to drive a liquid flow by applying electric potentials on the order of 1 V; at least a few tens of volts is required to generate EHD flows, which may not be preferable for aqueous solutions. In this study, we propose a novel method of generating a liquid flow through a channel with cross-sectional dimensions of 1 × 1 mm2, which is placed in an ion exchange membrane to separate the cation and anion transport pathways. When the optimized design of the experimental apparatus was used, EHD flows were successfully generated in aqueous solutions by applying a relatively low electric potential of 2.2 V, and the flow velocity was measured over a wide range of electrolyte concentrations by particle image velocimetry. It was found that high concentration gradients caused the rapid discharge of ions passing through the channel and contributed to achieving a flow speed on the order of 1 mm/s. EHD flows were also theoretically explained using the Navier-Stokes equations to model an ion-drag flow driven by nonequilibrium ion transport in external electric fields. This flow generation method is practical only when ion transport pathways are well controlled and effectively rectified. The present findings will lead to the development of a promising technology to control liquid flows in multiscale fluidic channels.

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

    Directory of Open Access Journals (Sweden)

    Ozi Adi Saputra


    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. On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO2 Adsorption. (United States)

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


    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 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Cation-exchanged SAPO-34 for adsorption-based hydrocarbon separations: predictions from dispersion-corrected DFT calculations. (United States)

    Fischer, Michael; Bell, Robert G


    The influence of the nature of the cation on the interaction of the silicoaluminophosphate SAPO-34 with small hydrocarbons (ethane, ethylene, acetylene, propane, propylene) is investigated using periodic density-functional theory calculations including a semi-empirical dispersion correction (DFT-D). Initial calculations are used to evaluate which of the guest-accessible cation sites in the chabazite-type structure is energetically preferred for a set of ten cations, which comprises four alkali metals (Li(+), Na(+), K(+), Rb(+)), three alkaline earth metals (Mg(2+), Ca(2+), Sr(2+)), and three transition metals (Cu(+), Ag(+), Fe(2+)). All eight cations that are likely to be found at the SII site (centre of a six-ring) are then included in the following investigation, which studies the interaction with the hydrocarbon guest molecules. In addition to the interaction energies, some trends and peculiarities regarding the adsorption geometries are analysed, and electron density difference plots obtained from the calculations are used to gain insights into the dominant interaction types. In addition to dispersion interactions, electrostatic and polarisation effects dominate for the main group cations, whereas significant orbital interactions are observed for unsaturated hydrocarbons interacting with transition metal (TM) cations. The differences between the interaction energies obtained for pairs of hydrocarbons of interest (such as ethylene-ethane and propylene-propane) deliver some qualitative insights: if this energy difference is large, it can be expected that the material will exhibit a high selectivity in the adsorption-based separation of alkene-alkane mixtures, which constitutes a problem of considerable industrial relevance. While the calculations show that TM-exchanged SAPO-34 materials are likely to exhibit a very high preference for alkenes over alkanes, the strong interaction may render an application in industrial processes impractical due to the large amount

  13. A new semi-empirical kinetic method for the determination of ion exchange constants for the counterions of cationic micelles. (United States)

    Khan, M Niyaz


    A new method, based upon semi-empirical kinetic approach, for the determination of ion exchange constant for ion exchange processes occurring between counterions at the cationic micellar surface is described in this review article. Basically, the method involves a reaction kinetic probe which gives observed pseudo-first-order rate constants (k(obs)) for a nucleophilic substitution reaction between the nonionic and anionic reactants (R and S) in the presence of a constant concentration of both reactants as well as cationic micelles and varying concentrations of an inert inorganic or organic salt (MX). The observed data (k(obs), versus [MX]) fit satisfactorily (in terms of residual errors) to an empirical equation which could be derived from an equation explaining the mechanism of the reaction of the kinetic probe in terms of pseudophase micellar (PM) model coupled with another empirical equation. This (another) empirical equation explains the effect of [MX] on cationic micellar binding constant (K(S)) of the anionic reactant (say S) and gives an empirical constant, K(X/S). The magnitude of K(X/S) is the measure of the ability of X(-) to expel S(-) from a cationic micellar pseudophase to the bulk aqueous phase through ion exchange X(-)/S(-). The values of K(X/S) and K(Y/S) (where Y(-) is another inert counterion) give the ion exchange constant, K(X)(Y) (=K(X)/K(Y) where K(X) and K(Y) represent cationic micellar binding constants of X(-) and Y(-), respectively). The suitability of this method is demonstrated by the use of three different reaction kinetic probes and various MX. Copyright 2010 Elsevier B.V. All rights reserved.

  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


    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. Nitrogen removal from wastewater through microbial electrolysis cells and cation exchange membrane (United States)


    Vulnerability of water resources to nutrients led to progressively stricter standards for wastewater effluents. Modification of the conventional procedures to meet the new standards is inevitable. New technologies should give a priority to nitrogen removal. In this paper, ammonium chloride and urine as nitrogen sources were used to investigate the capacity of a microbial electrolysis cell (MEC) configured by cation exchange membrane (CEM) for electrochemical removal of nitrogen over open-and closed-circuit potentials (OCP and CCP) during biodegradation of organic matter. Results obtained from this study indicated that CEM was permeable to both organic and ammonium nitrogen over OCP. Power substantially mediated ammonium migration from anodic wastewater to the cathode, as well. With a urine rich wastewater in the anode, the maximum rate of ammonium intake into the cathode varied from 34.2 to 40.6 mg/L.h over CCP compared to 10.5-14.9 mg/L.h over OCP. Ammonium separation over CCP was directly related to current. For 1.46-2.12 mmol electron produced, 20.5-29.7 mg-N ammonium was removed. Current also increased cathodic pH up to 12, a desirable pH for changing ammonium ion to ammonia gas. Results emphasized the potential for MEC in control of ammonium through ammonium separation and ammonia volatilization provided that membrane characteristic is considered in their development. PMID:24533446

  16. Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction. (United States)

    Kang, Il-Mo; Roh, Ki-Min


    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%).

  17. Facile and green fabrication of cation exchange membrane adsorber with unprecedented adsorption capacity for protein purification. (United States)

    Khan, M Kamran; Luo, Jianquan; Khan, Rashid; Fan, Jinxin; Wan, Yinhua


    Fabricating membrane adsorbers with high adsorption capacity and appreciable throughput for the separation and purification of protein products is challenging in biomedical and pharmaceutical industries. Herein, we report the synthesis of a novel membrane adsorber by functionalizing a nylon microfiltration membrane with alginate dialdehyde (ADA) followed by sulphonic addition, without any solvent usage, and its successful application in the purification of lysozyme. Taking advantage of abundant dual cation exchange (CEX) groups on sulphonic-ADA (S-ADA) ligands, this novel S-ADA-nylon membrane adsorber showed an unprecedented static binding capicity of 286mg/mL for lysozyme adsorption. Meanwhile, the prepared membrane adsorber could be easily regenerated (complete protein elution) under mild conditions and be reused at least for five times. Featured with a unique selectivity, the S-ADA-nylon membrane also captured lysozyme from chicken egg white solution with a high purity (100%) and a high recovery of 98%. The purified lysozyme showed similar specific activity as commercial product. The present work provides a facile, green and low-cost approach for the preparation of high-performance membrane adsorbers, which has a great potential in protein production. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Design of a strong cation exchange methodology for the evaluation of charge heterogeneity in glatiramer acetate. (United States)

    Campos-García, Víctor R; López-Morales, Carlos A; Benites-Zaragoza, Eleuterio; Jiménez-Miranda, Armando; Espinosa-de la Garza, Carlos E; Herrera-Fernández, Daniel; Padilla-Calderón, Jesús; Pérez, Néstor O; Flores-Ortiz, Luis F; Medina-Rivero, E


    Complex pharmaceuticals are in demand of competent analytical methods able to analyze charge heterogeneity as a critical quality attribute (CQA), in compliance with current regulatory expectations. A notorious example is glatiramer acetate (GA), a complex polypeptide mixture useful for the treatment of relapsing-remitting multiple sclerosis. This pharmaceutical challenges the current state of analytical technology in terms of the capacity to study their constituent species. Thus, a strong cation exchange methodology was designed under the lifecycle approach to support the establishment of GA identity, trough the evaluation of its chromatographic profile, which acts as a charge heterogeneity fingerprint. In this regard, a maximum relative margin of error of 5% for relative retention time and symmetry factor were proposed for the analytical target profile. The methodology met the proposed requirements after precision and specificity tests results, the former comprised of sensitivity and selectivity. Subsequently, method validation was conducted and showed that the method is able to differentiate between intact GA and heterogeneity profiles coming from stressed, fractioned or process-modified samples. In summary, these results provide evidence that the method is adequate to assess charge heterogeneity as a CQA of this complex pharmaceutical. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Effect of temperature on quantifying glycated (glycosylated) hemoglobin by cation-exchange chromatography. (United States)

    Flückiger, R; Woodtli, T


    As a consequence of nonideal chromatographic conditions, values for stable glycated hemoglobin (HbA1c) determined by cation-exchange chromatography in a commercial minicolumn system (y) or by "high-performance" liquid chromatography (x) differ markedly, yielding the regression line y = 0.82x + 0.6. With use of the protocol specified by the manufacturer, 20% of the HbA1c peak is not collected in the HbA1c fraction. Increasing the ionic strength of the eluting buffer by increasing the operating temperature to 28 degrees C increases the rate of elution from the minicolumn, making results of the two methods more closely comparable (y = 0.98x - 0.22). Because at a given pH the elution volume is determined primarily by the ionic strength, close limits on the composition of the eluting buffer are set by the temperature-dependence of its ionic strength. At a specified temperature and pH the position of a peak can be judged to within a volume of 1 mL if the conductivity of the eluent does not vary by more than +/- 0.05 mS.

  20. Modeling cation exchange capacity and soil water holding capacity from basic soil properties

    Directory of Open Access Journals (Sweden)

    Idowu Olorunfemi


    Full Text Available Cation exchange capacity (CEC is a good indicator of soil productivity and is useful for making recommendations of phosphorus, potassium, and magnesium for soils of different textures. Soil water holding capacity (SWHC defines the ability of a soil to hold water at a particular time of the season. This research predicted CEC and SWHC of soils using pedotransfer models developed (using Minitab 17 statistical software from basic soil properties (Sand(S, Clay(C, soil pH, soil organic carbon (SOC and verify the model by comparing the relationship between measured and estimated (obtained by PTFs CEC and SWHC in the Forest Vegetative Zone of Nigeria. For this study, a total of 105 sampling points in 35 different locations were sampled in the study areas. Three sampling points were randomly selected per location and three undisturbed samples were collected at each sampling point. The results showed success in predicting CEC and SWHC from basic soil properties. In this study, five linear regression models for predicting soil CEC and seven linear regression models for predicting SWHC from some soil physical and chemical properties were suggested. Model 5 [CEC = -13.93+2.645 pH +0.0446 C (%+2.267 SOC (%] was best for predicting CEC while model 12 [SWHC (%=36.0- 0.215 S (%+0.113 C (%+10.36 SOC (%] is the most acceptable model for predicting SWHC.

  1. Predicting cation exchange capacity from hygroscopic moisture in agricultural soils of Western Europe

    Energy Technology Data Exchange (ETDEWEB)

    Torrent, J.; Campillo, M.C. del; Barrón, V.


    Soil cation exchange capacity (CEC) depends on the extent and negative charge density of surfaces of soil mineral and organic components. Soil water sorption also depends on the extent of such surfaces, giving thus way to significant relationships between CEC and hygroscopic moisture (HM) in many soils. In this work, we explored whether CEC could be accurately predicted from HM in agricultural soils of Mediterranean and humid temperate areas in Western Europe. For this purpose, we examined 243 soils across a wide variation range of their intrinsic properties. Soil CEC was determined using 1 M ammonium acetate at pH 7 and HM at an equilibrium air relative humidity (RH) of 43% (HM43). Most of the variation of soil CEC was explained by HM43 through a linear function (CEC = 1.4 + 0.78HM43; R2 = 0.962; standard deviation = 2.30 cmolc/kg). Coefficients of the regression equation were similar for subgroups of soils differing in moisture regime, clay mineralogy, carbonate content and organic carbon content. Therefore, soil hygroscopic moisture measurements at a fixed RH level provided a simple, robust, inexpensive method for predicting soil CEC. (Author)

  2. Short communication: Predicting cation exchange capacity from hygroscopic moisture in agricultural soils of Western Europe

    Directory of Open Access Journals (Sweden)

    José Torrent


    Full Text Available Soil cation exchange capacity (CEC depends on the extent and negative charge density of surfaces of soil mineral and organic components. Soil water sorption also depends on the extent of such surfaces, giving thus way to significant relationships between CEC and hygroscopic moisture (HM in many soils. In this work, we explored whether CEC could be accurately predicted from HM in agricultural soils of Mediterranean and humid temperate areas in Western Europe. For this purpose, we examined 243 soils across a wide variation range of their intrinsic properties. Soil CEC was determined using 1 M ammonium acetate at pH 7 and HM at an equilibrium air relative humidity (RH of 43% (HM43. Most of the variation of soil CEC was explained by HM43 through a linear function (CEC = 1.4 + 0.78HM43; R2 = 0.962; standard deviation = 2.30 cmolc/kg. Coefficients of the regression equation were similar for subgroups of soils differing in moisture regime, clay mineralogy, carbonate content and organic carbon content. Therefore, soil hygroscopic moisture measurements at a fixed RH level provided a simple, robust, inexpensive method for predicting soil CEC.

  3. Isolation of lactoperoxidase using different cation exchange resins by batch and column procedures. (United States)

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


    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.

  4. Kinetics and Thermodynamics of Reserpine Adsorption onto Strong Acidic Cationic Exchange Fiber (United States)

    Guo, Zhanjing; Liu, Xiongmin; Huang, Hongmiao


    The kinetics and thermodynamics of the adsorption process of reserpine adsorbed onto the strong acidic cationic exchange fiber (SACEF) were studied by batch adsorption experiments. The adsorption capacity strongly depended on pH values, and the optimum reserpine adsorption onto the SACEF occurred at pH = 5 of reserpine solution. With the increase of temperature and initial concentration, the adsorption capacity increased. The equilibrium was attained within 20 mins. The adsorption process could be better described by the pseudo-second-order model and the Freundlich isotherm model. The calculated activation energy Ea was 4.35 kJ/mol. And the thermodynamic parameters were: 4.97thermodynamic parameters demonstrated that the adsorption was an endothermic, spontaneous and feasible process of physisorption within the temperature range between 283 K and 323 K and the initial concentration range between 100 mg/L and 300 mg/L. All the results showed that the SACEF had a good adsorption performance for the adsorption of reserpine from alcoholic solution. PMID:26422265

  5. Modacrylic anion-exchange fibers for Cr(VI) removal from chromium-plating rinse water in batch and flow-through column experiments. (United States)

    Lee, Seung-Chan; Kang, Jin-Kyu; Sim, Eun-Hye; Choi, Nag-Choul; Kim, Song-Bae


    The aim of this study was to investigate Cr(VI) removal from chromium-plating rinse water using modacrylic anion-exchange fibers (KaracaronTM KC31). Batch experiments were performed with synthetic Cr(VI) solutions to characterize the KC31 fibers in Cr(VI) removal. Cr(VI) removal by the fibers was affected by solution pH; the Cr(VI) removal capacity was the highest at pH 2 and decreased gradually with a pH increase from 2 to 12. In regeneration and reuse experiments, the Cr(VI) removal capacity remained above 37.0 mg g(-1) over five adsorption-desorption cycles, demonstrating that the fibers could be successfully regenerated with NaCl solution and reused. The maximum Cr(VI) removal capacity was determined to be 250.3 mg g(-1) from the Langmuir model. In Fourier-transform infrared spectra, a Cr = O peak newly appeared at 897 cm(-1) after Cr(VI) removal, whereas a Cr-O peak was detected at 772 cm(-1) due to the association of Cr(VI) ions with ion-exchange sites. X-ray photoelectron spectroscopy analyses demonstrated that Cr(VI) was partially reduced to Cr(III) after the ion exchange on the surfaces of the fibers. Batch experiments with chromium-plating rinse water (Cr(VI) concentration = 1178.8 mg L(-1)) showed that the fibers had a Cr(VI) removal capacity of 28.1-186.4 mg g(-1) under the given conditions (fiber dose = 1-10 g L(-1)). Column experiments (column length = 10 cm, inner diameter = 2.5 cm) were conducted to examine Cr(VI) removal from chromium-plating rinse water by the fibers under flow-through column conditions. The Cr(VI) removal capacities for the fibers at flow rates of 0.5 and 1.0 mL min(-1) were 214.8 and 171.5 mg g(-1), respectively. This study demonstrates that KC31 fibers are effective in the removal of Cr(VI) ions from chromium-plating rinse water.

  6. Ionic polymer-metal composite actuators obtained from radiation-grafted cation- and anion-exchange membranes. (United States)

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


    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.

  7. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells? (United States)

    Šljukić, Biljana; Morais, Ana L.; Santos, Diogo M. F.; Sequeira, César A. C.


    Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load. PMID:24958292

  8. 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


    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...

  9. Ga for Zn Cation Exchange Allows for Highly Luminescent and Photostable InZnP-Based Quantum Dots (United States)


    In this work, we demonstrate that a preferential Ga-for-Zn cation exchange is responsible for the increase in photoluminescence that is observed when gallium oleate is added to InZnP alloy QDs. By exposing InZnP QDs with varying Zn/In ratios to gallium oleate and monitoring their optical properties, composition, and size, we conclude that Ga3+ preferentially replaces Zn2+, leading to the formation of InZnP/InGaP core/graded-shell QDs. This cation exchange reaction results in a large increase of the QD photoluminescence, but only for InZnP QDs with Zn/In ≥ 0.5. For InP QDs that do not contain zinc, Ga is most likely incorporated only on the quantum dot surface, and a PL enhancement is not observed. After further growth of a GaP shell and a lattice-matched ZnSeS outer shell, the cation-exchanged InZnP/InGaP QDs continue to exhibit superior PL QY (over 70%) and stability under long-term illumination (840 h, 5 weeks) compared to InZnP cores with the same shells. These results provide important mechanistic insights into recent improvements in InP-based QDs for luminescent applications. PMID:28706347

  10. Sorption of chlorimuron-ethyl on montmorillonite clays: effects of exchangeable cations, pH, and ionic strength. (United States)

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


    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.

  11. Modelling of geochemical reactions and experimental cation exchange in MX 80 bentonite. (United States)

    Montes-H, G; Fritz, B; Clement, A; Michau, N


    Bentonites are widely used for waste repository systems because of their hydrodynamic, surface and chemical-retention properties. MX 80 bentonite (bentonite of Wyoming) contains approximately 85% Na/Ca-montmorillonite and 15% accessory minerals. The dominant presence of Na/Ca-montmorillonite in this clay mineral could cause it to perform exceptionally well as an engineered barrier for a radioactive waste repository because this buffer material is expected to fill up by swelling the void between canisters containing waste and the surrounding ground. However, the Na/Ca-montmorillonite could be transformed to other clay minerals as a function of time under repository conditions. Previous modelling studies based on the hydrolysis reactions have shown that the Na/Ca-montmorillonite-to-Ca-montmorillonite conversion is the most significant chemical transformation. In fact, this chemical process appears to be a simple cation exchange into the engineered barrier. The purpose of the present study was two-fold. Firstly, it was hoped to predict the newly formed products of bentonite-fluid reactions under repository conditions by applying a thermokinetic hydrochemical code (KIRMAT: Kinetic Reactions and Mass Transport). The system modelled herein was considered to consist of a 1-m thick zone of water-saturated engineered barrier. This non-equilibrated system was placed in contact with a geological fluid on one side, which was then allowed to diffuse into the barrier, while the other side was kept in contact with iron-charged water. Reducing initial conditions ( [P(O)2 approximately equals 0] ; Eh=-200 mV) and a constant reaction temperature (100 degrees C) were considered. Secondly, it was hoped to estimate the influence of inter-layer cations (Ca and Na) on the swelling behaviour of the MX 80 bentonite by using an isothermal system of water vapour adsorption and an environmental scanning electron microscope (ESEM) coupled with a digital image analysis (DIA) program. Here, the

  12. Existence or absence of bandgap bowing in II-VI ternary alloys: Comparison between common-anion and common-cation cases (United States)

    Tit, Nacir; Obaidat, I. M.; Reshak, A. H.; Alawadhi, H.


    The common-anion and common-cation II-VI ternary alloys of the family Cd(Zn)Se(Te) are theoretically investigated based on two different methods. Within the virtual-crystal approximation (VCA), both the sp3s*-tight-binding method, with the inclusion of spin-orbit coupling, and the first-principle full-potential linear augmented plane waves (FP-LAPW) technique are employed to determine the alloy constituents' charge states (ionicities) and degree of bond polarity. The results show that: (i) in the common-cation ternary alloys (i.e., CdSexTe1-x and ZnSexTe1-x), the anions alter a strong competition in trapping more charge. Such a competition builds up a compromised effect yielding the bowing behaviour. Whereas, (ii) in the common-anion ternary alloys (i.e., CdyZn1-yTe and CdyZn1-ySe), the absence of such competition would cause the complete absence of bandgap bowing behaviour. The variation of the bandgap is found to be rather close to linear. The obtained good agreement between our theoretical results and the recently available photoluminescence data does further corroborate our claims.

  13. Cation Exchange Resins and colonic perforation. What surgeons need to know (United States)

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


    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

  14. Microcalorimetric study of adsorption of human monoclonal antibodies on cation exchange chromatographic materials. (United States)

    Dieterle, Michael; Blaschke, Tim; Hasse, Hans


    Adsorption of two human monoclonal antibodies on two different strong cation exchange resins is studied by isothermal titration microcalorimetry and independent adsorption isotherm measurements. The pH value is varied between 4.5 and 7.0, using different buffer systems, the temperature is always 25 degrees C. The adsorption isotherm data is fitted using two different Langmuir type models. Combining the calorimetric and the adsorption data, the specific enthalpy of adsorption of the protein Deltah(p)(ads) is determined. At pH values near 7.0, where the antibodies are only weakly charged, the adsorption is exothermal. At small loadings the absolute number of Deltah(p)(ads) is then large and almost constant but it significantly decreases at higher loadings. This shows that the arrangement of antibody molecules on the absorber material depends on the loading and is less favourable at higher loadings. Despite the high positive charge of the antibody at pH values of about 5 the value of Deltah(p)(ads) is almost zero along the entire isotherm. Furthermore, at pH 4.5 even endothermal effects are observed, although high binding capacities are found. At these conditions the adsorption process seems to be strongly influenced by the ions bound to the antibody. Their release upon absorption explains the endothermal caloric effect. The adsorption equilibrium constant K(eq) is calculated from the isotherms. From Deltag(p)(ads) and the calorimetric results for Deltah(p)(ads), Deltas(p)(ads), the entropy change upon adsorption of the protein is found for the different studied conditions.

  15. Molecular Dynamics Study of Hydrogen on Alkali-Earth Metal Cations Exchanged X Zeolites

    Directory of Open Access Journals (Sweden)

    Du Xiaoming


    Full Text Available The self-diffusion of hydrogen in Ca2+-, Mg2+- and Ba2+-exchanged X zeolites (Mg46X, Ca46X, and Ba46X has been studied by molecular dynamics (MD simulations for various temperatures and loadings. The results indicate that in the temperature range of 77–298 K and the loading range of 1–80 molecules/cell, the self-diffusion coefficients are found to range from 1.2×10-9 m2·s−1 to 2.3×10-7 m2·s−1 which are in good agreement with the experimental values from the quasielastic neutron scattering (QENS and pulse field gradients nuclear magnetic resonance (PFG NMR measurements. The self-diffusion coefficients decrease with loading due to packing of sorbate-sorbate molecules which causes frequent collusion among hydrogen molecules in pores and increases with increasing temperature because increasing the kinetic energy of the gas molecules enlarges the mean free path of gas molecule. The mechanism of diffusion of hydrogen molecules in these zeolites is transition diffusion. Knudsen diffusion occurs at low loading and the molecular bulk diffusion occurs at higher loading. For given temperature and loading, the self-diffusion coefficients decrease in the order Ba46Xcations. Moreover, the effect of concentration of molecular hydrogen on self-diffusion coefficient also is analyzed using radial distribution function (RDF.

  16. Ambient soil cation exchange capacity inversely associates with infectious and parasitic disease risk in regional Australia. (United States)

    Liddicoat, Craig; Bi, Peng; Waycott, Michelle; Glover, John; Breed, Martin; Weinstein, Philip


    Human contact with soil may be important for building and maintaining normal healthy immune defence mechanisms, however this idea remains untested at the population-level. In this continent-wide, cross-sectional study we examine the possible public health benefit of ambient exposures to soil of high cation exchange capacity (CEC), a surrogate for potential immunomodulatory soil microbial diversity. We compare distributions of normalized mean 2011/12-2012/13 age-standardized public hospital admission rates (cumulative incidence) for infectious and parasitic diseases across regional Australia (representing an average of 29,516 patients/year in 228 local government areas), within tertiles of socioeconomic status and soil exposure. To test the significance of soil CEC, we use probabilistic individual-level environmental exposure data (with or without soil), and group-level variables, in robust non-parametric multilevel modelling to predict disease rates in unseen groups. Our results show that in socioeconomically-deprived areas with high CEC soils, rates of infectious and parasitic disease are significantly lower than areas with low CEC soils. Also, health inequality (relative risk) due to socioeconomic status is significantly lower in areas with high CEC soils compared to low CEC soils (Δ relative risk = 0.47; 95% CI: 0.13, 0.82). Including soil exposure when modelling rates of infectious and parasitic disease significantly improves prediction performance, explaining an additional 7.5% (Δ r 2  = 0.075; 95% CI: 0.05, 0.10) of variation in disease risk, in local government areas that were not used for model building. Our findings suggest that exposure to high CEC soils (typically high soil biodiversity) associates with reduced risk of infectious and parasitic diseases, particularly in lower socioeconomic areas. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. 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


    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.

  18. Effect of cation exchange resin treatment and addition on sugar as anti-caking agent on retention of nutritional and sensory quality of lemon juice powder during storage

    National Research Council Canada - National Science Library

    Sharma, Satish K; Kaushal, B B. L; Sharma, P C


    Lemon juices clarified with enzymatic treatment with and without cation exchange resin treatment were concentrated to 60o Brix in a vacuum evaporator and converted into powders by foam mat drying technique...

  19. Preparation of poly(glycidylmethacrylate-divinylbenzene) weak acid cation exchange stationary phases with succinic anhydride, phthalic anhydride, and maleic anhydride for ion chromatography. (United States)

    Liu, Junwei; Wang, Yong; Wu, Shuchao; Zhang, Peimin; Zhu, Yan


    In this work, poly(glycidylmethacrylate-divinylbenzene) microspheres were prepared and applied for the preparation of weak acid cation exchange stationary phases. Succinic anhydride, phthalic anhydride, and maleic anhydride were selected as carboxylation reagents to prepare three weak acid cation exchangers by direct chemical derivatization reaction without solvent or catalyst. The diameters and dispersity of the microspheres were characterized by scanning electron microscopy; the amount of accessible epoxy groups and mechanical stability were also measured. The weak acid cation exchangers were characterized by Fourier transform infrared spectroscopy; the content of carboxyl groups was measured by traditional acid base titration method. The chromatographic properties were characterized and compared by separating alkali, alkaline earth metal ions and ammonium and polar amines. The separation properties enhanced in the order of succinic anhydride, phthalic anhydride, and maleic anhydride modified poly(glycidylmethacrylate-divinylbenzene) cation exchangers. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Directory of Open Access Journals (Sweden)

    Yuan J


    Full Text Available Jing Yuan, Yanan Gao, Xinyu Wang, Hongzhuo Liu, Xin Che, Lu Xu, Yang Yang, Qifang Wang, Yan Wang, Sanming LiSchool of Pharmacy, Shenyang Pharmaceutical University, Shenyang, People’s Republic of China Abstract: 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. Keywords: ion-exchange fibers, ionic reaction, drug load and release, opposing exchange kinetics, thermodynamics, influences

  1. Indirect UV detection-ion-exclusion/cation-exchange chromatography of common inorganic ions with sulfosalicylic acid eluent. (United States)

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


    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.

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

    KAUST Repository

    Samin, Umer A.


    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.

  3. Comparison between methods using copper, lanthanum, and colorimetry for the determination of the cation exchange capacity of plant cell walls. (United States)

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


    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.

  4. Mapping cation exchange capacity using a Veris-3100 instrument and invVERIS modelling software. (United States)

    Koganti, T; Moral, F J; Rebollo, F J; Huang, J; Triantafilis, J


    The cation exchange capacity (CEC) is one of the most important soil properties as it influences soil's ability to hold essential nutrients. It also acts as an index of structural resilience. In this study, we demonstrate a method for 3-dimensional mapping of CEC across a study field in south-west Spain. We do this by establishing a linear regression (LR) between the calculated true electrical conductivity (σ - mS/m) and measured CEC (cmol(+)/kg) at various depths. We estimate σ by inverting Veris-3100 data (ECa - mS/m) collected along 47 parallel transects spaced 12m apart. We invert the ECa data acquired from both shallow (0-0.3m) and deep (0-0.9m) array configurations, using a quasi-three-dimensional inversion algorithm (invVeris V1.1). The CEC data was acquired at 40 locations and from the topsoil (0-0.3m), subsurface (0.3-0.6m) and subsoil (0.6-0.9m). The best LR between σ and CEC was achieved using S2 inversion algorithm using a damping factor (λ)=18. The LR (CEC=1.77+0.33×σ) had a large coefficient of determination (R(2)=0.89). To determine the predictive capability of the LR, we validated the model using a cross-validation. Given the high accuracy (root-mean-square-error [RMSE]=1.69 cmol(+)/kg), small bias (mean-error [ME]=-0.00cmol(+)/kg) and large coefficient of determination (R(2)=0.88) and Lin's concordance (0.94), between measured and predicted CEC and at various depths, we conclude we were well able to predict the CEC distribution in topsoil and the subsurface. However, the predictions made in the subsoil were poor due to limited data availability in areas where ECa changed rapidly from small to large values. In this regard, improvements in prediction accuracy can be achieved by collection of ECa in more closely spaced transects, particularly in areas where ECa varies over short spatial scales. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Ion exchange equilibrium constants

    CERN Document Server

    Marcus, Y


    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

  6. Layered assemblies of a dialuminum-substituted silicotungstate trimer and the reversible interlayer cation-exchange properties. (United States)

    Kikukawa, Yuji; Yamaguchi, Kazuya; Hibino, Mitsuhiro; Mizuno, Noritaka


    Two polyoxometalate assemblies, TBA(9)[{γ-H(2)SiW(10)O(36)Al(2)(μ-OH)(2)(μ-OH)}(3)] (1; TBA = tetra-n-butylammonium) and TBA(6)Li(3)[{γ-H(2)SiW(10)O(36)Al(2)(μ-OH)(2)(μ-OH)}(3)]·18H(2)O (2), were synthesized by trimerization of a dialuminum-substituted silicotungstate monomer. Both 1 and 2 possessed a layered structure composed of a basal sheet unit [TBA(3){γ-H(2)SiW(10)O(36)Al(2)(μ-OH)(2)(μ-OH)}(3)](6-) and interlayer cations. The interconversion between 1 and 2 reversibly took place through interlayer cation exchange. © 2011 American Chemical Society

  7. The investigation on cationic exchange capacity of zeolites: the use as selective ion trappers in the electrokinetic soil technique. (United States)

    Ursini, Ornella; Lilla, Edo; Montanari, Roberta


    The cation exchange capacity (CEC) of porous zeolites allows to adsorb in the framework cavities the cations as pollutant heavy metal ions. We investigate the CEC behaviour of different zeolites in different experimental conditions; in solution where the ion's mobility is spontaneous and free and in the electrokinetic system where the ion's mobility is driven by the electric field. The aim of this study is to investigate if the CEC is an useful property to create a special interface region of zeolites, that if placed in the electrokinetic cell, just before the cathode, could allow to capture and concentrate the heavy metallic ions, during their migrating process. The zeolite 13X investigated in the electrokinetic proofs, retains a good high ions adsorption, even if quite smaller than the relevant free solution condition and well acts as confined trap for the heavy metal ions. In fact no trace of metallic deposition are present on the electrode's surface.

  8. Swelling and electro-osmotic properties of cation-exchange membranes with different structures in methanol-water media (United States)

    Barragán, V. M.; Villaluenga, J. P. G.; Godino, M. P.; Izquierdo-Gil, M. A.; Ruiz-Bauzá, C.; Seoane, B.

    Electro-osmosis experiments through three cation-exchange membranes with different morphology and similar electric properties have been performed using methanol-water solutions under different experimental conditions. The influence on the electro-osmotic transport of the percentage of methanol on solvent with two different electrolytes, NaCl and LiCl, has been studied. The experimental results show that the presence of methanol in the solutions affects strongly the electro-osmotic flow, and this influence is different depending on the membrane morphology. Correlations among electro-osmotic permeability, swelling behavior, and cell resistance are studied for these membrane systems at different percentages of methanol in solvent.

  9. Three-dimensional lanthanide anionic metal-organic frameworks with tunable luminescent properties induced by cation exchange. (United States)

    Lu, Wen-Guan; Jiang, Long; Feng, Xiao-Long; Lu, Tong-Bu


    Three 3D lanthanide anionic metal-organic frameworks {K(5)[Ln(5)(IDC)(4)(ox)(4)]}(n) x (20H(2)O)(n) with 1D channels were synthesized under hydrothermal conditions [Ln = Gd (1), Tb (2), and Dy (3)]. The K(+) ions within the 1D channel are easily exchanged with various cations. The emission intensities of Tb(III) in 2 increased significantly upon the addition of Ca(2+) ions, while the introduction of other metal ions caused the intensities to be either unchanged or weakened.

  10. Synthesis and characterization of a novel hybrid material as amphoteric ion exchanger for simultaneous removal of cations and anions. (United States)

    Shah, Brijesh; Chudasama, Uma


    A new hybrid chelating ion exchanger zirconium diethylene triamine (ZrD) has been synthesized by a simple sol-gel route using inexpensive and easily available chemicals. ZrD has been characterized for elemental analysis (ICP-AES, CHN analysis), TGA, FTIR, X-ray diffraction, SEM and EDX. Physical and ion exchange characteristics as well as chemical stability of the material in various media have been studied. Structural determination reveals that ZrD exhibits amphoteric character. Anion exchange capacity (AEC) for Cl(-), Br(-), Cr2O7(2-), F(-) and AsO4(3-) has been determined. Cations are exchanged through chelation where coordinating sites are offered by nitrogen atoms present in the amine groups of ZrD. Distribution coefficient Kd for Co(2+), Ni(2+), Cu(2+), Zn(2+) (transition metal ions) and Hg(2+), Cd(2+), Pb(2+) (heavy metal ions) has been evaluated by batch equilibration techniques in aqueous and various electrolyte media/concentrations. Based on α the separation factor, a few binary separations have been performed on a chromatographic column packed with ZrD. The amphoteric behaviour of ZrD has been demonstrated by simultaneous exchange of Cu(2+) and Cl(-) in CuCl2. A study on the regeneration and reuse of ZrD indicates that it is effective upto four cycles without much decline in performance. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    V. Romero


    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.

  12. 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


    and dimethylarsinoylacetic acid, whereas the cationic arsenocholine ion and tetramethylarsonium ion were not affected. The accuracy of the method for DMA, AsB and TMAs was validated with the CRMs DORM-2 and BCR626 Tuna. The concentrations found for arsenobetaine, dimethylarsinic acid and tetramethylarsonium ion were within...

  13. Simultaneous separation and detection of anions and thiophilic cations using capillary-size anion exchange chromatography with suppressed conductivity detection. (United States)

    Sötz, Veronika Anna; Kochmann, Sven


    In this fundamental study, the simultaneous separation and detection of anions and thiophilic cations in anion exchange chromatography with suppressed conductivity detection is investigated. Mercury(II) and cadmium(II) served as model analytes. Separation and detection was performed by introducing 2-mercaptoethanesulfonate, which forms complexes with both mercury and cadmium with a strong metal-sulfur bond, into the KOH eluent. Additional to the separation on the column, these complexes were able to pass the suppressor. Subsequently, they could be detected as negative peaks. A simple model for the separation mechanism was developed based on these results. Furthermore, the effect of the eluent concentration on the retention factors of both cation complexes and standard anions was examined and quantified. It revealed that the concentration of 2-mercaptoethanesulfonate has more influence on the cations than the KOH concentration. Also, 2.0 mM of 2-mercaptoethanesulfonate had about the same effect on the anion separation as 60 mM KOH. Finally, selectivity and detection limits were investigated. The detection limits were 4.9 μM for mercury and 2.2 μM for cadmium. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Suppressing Shuttle Effect Using Janus Cation Exchange Membrane for High-Performance Lithium-Sulfur Battery Separator. (United States)

    Li, Zhen; Han, Yu; Wei, Junhua; Wang, Wenqiang; Cao, Tiantian; Xu, Shengming; Xu, Zhenghe


    Suppressing the shuttle effect of polysulfide ions to obtain high durability and good electrochemical performance is of great concern in the field of lithium-sulfur batteries. To address this issue, a Janus membrane consisting of an ultrathin dense layer and a robust microporous layer is fabricated using cation exchange resin. Different from the composite membranes made from polyolefin membranes, the multiple layers of the Janus membrane in this study are synchronously generated by one step, getting rid of the additional complex coating processes. Excellent overall performance is obtained by the cooperation of multiple factors. The excellent ionic selectivity of cation exchange resin renders a great suppression of the shuttle effect, endowing the lithium-sulfur battery with high Coulombic efficiency of 92.0-99.0% (LiNO3-free electrolyte). The ultrathin property of a dense layer renders a low ionic resistance, resulting in 60% higher discharge capacity over the entire C-rates (versus the control sample with Celgard 2400 membrane). The robust macroporous layer supports the ultrathin layer to achieve a free-standing property, ensuring the usability of the Janus membrane.

  15. Assessment of plasma amino acid profile in autism using cation-exchange chromatography with postcolumn derivatization by ninhydrin. (United States)

    Zaki, Mona Mohamed; Abdel-Al, Hala; Al-Sawi, Mohamed


    Autism is a heterogeneous neurodevelopmental disorder. This study aimed to assess the clinical significance of amino acid profile assay in autism using cation-exchange chromatography with ninhydrin postcolumn derivatization. This study included 42 autistic children and 26 apparently healthy children. All participants were subjected to the assay of plasma amino acids (essential, nonessential, and nonstandard) using cation-exchange chromatography with postcolumn derivatization by ninhydrin. The levels of most of the essential amino acids were significantly lower in autistic children than controls. As regards nonessential amino acids, significantly lower levels for plasma cysteine, tyrosine, and serine and significantly higher levels for plasma glutamic acid were recorded in autistic children than controls. Finally, the autistic group demonstrated significantly lower levels of α-aminoadipic acid, carnosine, and β-alanine and significantly higher levels of hydroxyproline, phosphoserine, β-amino-isobutyric acid, and ammonia as compared to controls. The study revealed that autistic children exhibit distinct alterations in the plasma levels of some amino acids, which can in turn participate in the disease etiology and can be applied as a diagnostic tool for early detection of autism.

  16. Comparison of gaseous oxidized Hg measured by KCl-coated denuders, and nylon and cation exchange membranes. (United States)

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


    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.

  17. Uncertainties of Gaseous Oxidized Mercury Measurements Using KCl-Coated Denuders, Cation-Exchange Membranes, and Nylon Membranes: Humidity Influences. (United States)

    Huang, Jiaoyan; Gustin, Mae Sexauer


    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.

  18. Room Temperature Cation Exchange Reaction in Nanocrystals for Ultrasensitive Speciation Analysis of Silver Ions and Silver Nanoparticles. (United States)

    Huang, Ke; Xu, Kailai; Tang, Jie; Yang, Lu; Zhou, Jingrong; Hou, Xiandeng; Zheng, Chengbin


    To evaluate the toxicity of silver nanoparticles (AgNPs) and Ag(+) and gain deep insight into the transformation of AgNPs in the environment or organisms, ultrasensitive analytical methods are needed for their speciation analysis. About 40-fold of Cd(2+) in CdTe ionic nanocrystals can be "bombarded-and-exploded" (exchanged) in less than 1 min simply by mixing the nanocrystals with Ag(+) solution at room temperature, while this cation exchange reaction did not occur when only silver nanoparticles were present. On the basis of this striking difference, an ultrasensitive method was developed for speciation analysis of Ag(+) and AgNPs in complex matrices. The released Cd(2+) was reduced to its volatile species by sodium tetrahydroborate, which was separated and swept to an inductively coupled plasma mass spectrometer (ICPMS) or an atomic fluorescence spectrometer (AFS) for the indirect but ultrasensitive detection of Ag(+). Owing to the remarkable signal amplification via the cation exchange reaction and the advantages of chemical vapor generation for sampling, the limit of detection was 0.0003 μg L(-1) for Ag(+) by ICPMS, which was improved by 100-fold compared to the conventional method. Relative standard deviations are better than 2.5% at a concentration of 0.5 μg L(-1) Ag(+) or AgNPs regardless of the detector. The proposed method retains several unique advantages, including ultrahigh sensitivity, speciation analysis, simplicity and being organic reagent-free, and has been successfully utilized for speciation analysis of Ag(+) and AgNPs in environmental water samples and paramecium cells.

  19. 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. (United States)

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


    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.

  20. [Preparation and retention mechanism of a mixed-mode reversed-phase/strong-cationic-exchange chromatographic packing]. (United States)

    Peng, Xitian; Wang, Jue; Feng, Yuqi


    A simple and efficient method has been proposed for the preparation of octyl-sulfonic co-bonded silica (OSS) packing by the method of "mixed ligand". The resulting OSS packing was characterized by elemental analysis and ion-exchange capacity to prove the successful immobilization of octyl and sulfonic groups on the surface of silica gel. Then the retention mechanism of several basic analytes on the developed OSS phases was evaluated under the conditions of reversed-phase liquid chromatography (RPLC) mobile phase. The results indicated that the OSS stationary phases demonstrated a mixed-mode reversed-phase/strong-cationic-exchange (RP/SCX) retention mechanism and ion-exchange interaction maybe dominate the retention of the basic analytes. By changing the salt concentration of mobile phase, the one-site and two-site mixed-mode retention models of the several basic analytes on the OSS phases were obtained by investigating the logarithm and reciprocal relationships of retention factor and salt concentration. On the basis of the linear fitting of the two mathematical equations of the retention models, the experimental results demonstrated that the two-site model was more suitable for the description of the retention mechanism of the basic analytes on the OSS phases. Furthermore, the individual RP or SCX contribution to total retention was obtained according to the mathematical equations of the two-site retention mechanism, which can provide some valuable guidance for the separation of complex samples.

  1. Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Exchangeable Cation Species of Zeolites


    Moses Wazingwa Munthali; Erni Johan; Naoto Matsue


    The saturation of negative charges of zeolites by specific cations to modify their physicochemical and catalytic properties has broadened the applications of zeolites. The adsorption behavior of H+ to Li+, Na+, K+, Rb+ and Cs+-saturated Linde-type A, Na-P1, mordenite, X type and Y type zeolites was evaluated at different pH-pM, where pH-pM is equal to log {(M+)/(H+)} and M+ represents either Li+, Na+, K+, Rb+, or Cs+. In all cases, with decreasing pH-pM, the amounts of alkali metal retention ...

  2. 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. (United States)

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


    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). Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Transport of Divalent Cations (United States)

    Van de Geijn, Siebe C.; Petit, Charles M.


    The cation exchange capacity of the intact xylem vessels in cut shoots of papyrus (Cyperus papyrus spec.) has been determined. The cation exchange capacity is independent of the cation concentration in the transpiration stream, and is equal for Ca and Co. The high value of the cation exchange capacity (0.6 to 1 × 10−7 equivalents per square centimeter vessel wall surface) leads to the hypothesis that the porous structure of the vessel wall, and not only the inner vessel wall surface, acts as a cation exchanger. Differences between anion ([32P]phosphate, [45Ca]EDTA2−, [115Cdm]-EDTA2−), and cation ([45Ca]2+, [115Cdm]2+) movement are explained in terms of transport with the transpiration flux or by exchange reactions. The competition between exchange sites and natural or synthetic ligands for the divalent cations is discussed. Images PMID:16661112

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

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


    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.

  5. Modeling data of copper(II) sorption onto the composite sorbent based on cation exchanger and tin(IV) hydroxide (United States)

    Ikanina, Elena V.; Kalyaeva, Mariya I.; Markov, Vyacheslav F.


    The methodology of stepwise synthesis of the composite sorbent based on cation exchanger and tin(IV) hydroxide was demonstrated. The results of copper(II) sorption onto the composite sorbent are presented. Langmuir, Freundlich and Temkin adsorption isotherms were used in mathematical modeling of the sorption data. The Langmuir model most accurately describes the sorption process. The constants of the Langmuir model and the specific surface area of the composite sorbent were defined. Granules of the composite sorbent were studied by scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDXMA). The distribution coefficients of copper(II) in the composite sorbent and the sorption degree from CuSO4 aqueous solutions of various concentrations were computed.

  6. Dispersive micro solid phase extraction of amantadine, rimantadine and memantine in chicken muscle with magnetic cation exchange polymer. (United States)

    Chen, Dawei; Miao, Hong; Zhao, Yunfeng; Wu, Yongning


    This study demonstrated a novel dispersive micro solid phase extraction (DMSPE) method for extraction of adamantane drugs (amantadine, rimantadine and memantine) in chicken muscle. The adamantane drugs were extracted from chicken muscle using 1% acidic acetonitrile as extraction solvent. The cleanup of fatty matrices from analytes was achieved by the DMSPE technique using magnetic cation exchange polymer as adsorbent. In this procedure, the experimental parameters and conditions were optimized in detail for the improvement of extraction efficiency. The method showed low limit of detection of 0.03μg/kg and recoveries of the analytes ranged from 87.2% to 109.3% for adamantane drugs. The proposed DMSPE method proved to be simple, effective and suitable for the treatment of adamantane drugs in chicken muscle with a relatively shorter extraction time. Copyright © 2017. Published by Elsevier B.V.

  7. 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.


    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

  8. Common Ion Effects In Zeoponic Substrates: Dissolution And Cation Exchange Variations Due to Additions of Calcite, Dolomite and Wollastonite (United States)

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


    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

  9. Electrochemical characterization of mixed matrix heterogeneous cation exchange membranes modified by simultaneous using ilmenite-co-iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Sayed Mohsen; Hamidi, Alireza; Moghadassi, Abdolreza [Faculty of Engineering, Arak University, Arak (Iran, Islamic Republic of); Madaeni, Sayed Siavash [Razi University, Kermanshah (Iran, Islamic Republic of)


    Mixed matrix heterogeneous cation exchange membranes were prepared by solution casting technique. Ilmenite-co-iron oxide nanoparticle was also employed as inorganic filler additive in membrane fabrication. The effect of the used additives on membrane electrochemical properties was studied. Membrane ion exchange capacity, membrane potential, transport number and selectivity all were improved by use of FeTiO{sub 3}/Fe{sub 3}O{sub 4} nanoparticles in membrane matrix. Utilizing FeTiO{sub 3}-co-Fe{sub 3}O{sub 4} nanoparticles in the casting solution also led to increase in ionic flux obviously. The modified membranes containing FeTiO{sub 3}-co-Fe{sub 3}O{sub 4} nanoparticles showed higher transport number, selectivity and ionic flux compared to modified membrane containing ilmenite. Electrodialysis experiment in laboratory scale also showed higher cation removal for modified membrane containing FeTiO{sub 3}-co-Fe{sub 3}O{sub 4} nanoparticles compared to other modified membranes and pristine ones. Results showed that membrane areal electrical resistance declined sharply by use of FeTiO{sub 3}-co-Fe{sub 3}O{sub 4} nanoparticles in membrane matrix. Moreover, modified membrane containing ilmenite showed lower electrical resistance compared to others. Results showed that oxidative stability of membranes was decreased slightly by use of FeTiO{sub 3}/Fe{sub 3}O{sub 4} nanoparticles in membrane matrix. The results revealed that modified membranes in this study are comparable with that of other commercial ones.

  10. Advance chromatin extraction enhances performance and productivity of cation exchange chromatography-based capture of Immunoglobulin G monoclonal antibodies. (United States)

    Nian, Rui; Gagnon, Pete


    The impact of host cell-derived chromatin was investigated on the performance and productivity of cation exchange chromatography as a method for capture-purification of an IgG monoclonal antibody. Cell culture supernatant was prepared for loading by titration to pH 6.0, dilution with water to a conductivity of 4mS/cm, then microfiltration to remove solids. DNA content was reduced 99% to 30ppm, histone host cell protein content by 76% to 6300ppm, non-histone host cell protein content by 15% to 321,000ppm, and aggregates from 33% to 15%. IgG recovery was 83%. An alternative preparation was performed, adding octanoic acid, allantoin, and electropositive particles to the harvest at pH 5.3, then removing solids. DNA content was reduced toaggregates were reduced to 2.4%. IgG recovery was 95%. This treatment increased dynamic capacity (DBC) of cation exchange capture to 173g/L and enabled the column to reduce non-histone host proteins to 671ppm. Step recovery was 99%. A single multimodal polishing step further reduced them to 15ppm and aggregates to <0.1%. Overall process recovery was 89%. Productivity at feed stream IgG concentrations of 5-10g/L was roughly double the productivity of a same-size protein A column with a DBC of 55g/L. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

  11. The use of laboratory-determined ion exchange parameters in the predictive modelling of field-scale major cation migration in groundwater over a 40-year period. (United States)

    Carlyle, Harriet F; Tellam, John H; Parker, Karen E


    An attempt has been made to estimate quantitatively cation concentration changes as estuary water invades a Triassic Sandstone aquifer in northwest England. Cation exchange capacities and selectivity coefficients for Na(+), K(+), Ca(2+), and Mg(2+) were measured in the laboratory using standard techniques. Selectivity coefficients were also determined using a method involving optimized back-calculation from flushing experiments, thus permitting better representation of field conditions; in all cases, the Gaines-Thomas/constant cation exchange capacity (CEC) model was found to be a reasonable, though not perfect, first description. The exchange parameters interpreted from the laboratory experiments were used in a one-dimensional reactive transport mixing cell model, and predictions compared with field pumping well data (Cl and hardness spanning a period of around 40 years, and full major ion analyses in approximately 1980). The concentration patterns predicted using Gaines-Thomas exchange with calcite equilibrium were similar to the observed patterns, but the concentrations of the divalent ions were significantly overestimated, as were 1980 sulphate concentrations, and 1980 alkalinity concentrations were underestimated. Including representation of sulphate reduction in the estuarine alluvium failed to replicate 1980 HCO(3) and pH values. However, by including partial CO(2) degassing following sulphate reduction, a process for which there is 34S and 18O evidence from a previous study, a good match for SO(4), HCO(3), and pH was attained. Using this modified estuary water and averaged values from the laboratory ion exchange parameter determinations, good predictions for the field cation data were obtained. It is concluded that the Gaines-Thomas/constant exchange capacity model with averaged parameter values can be used successfully in ion exchange predictions in this aquifer at a regional scale and over extended time scales, despite the numerous assumptions inherent in

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



    Dinar Dilshatovich Fazullin; Gennady Vitalevich Mavrin; Michael Pavlovich Sokolov


    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, material...

  14. Modification of the quality of water injected into Louisiana gulf coast sands: Effects of cation exchange (United States)

    Hanor, Jeffrey S.


    Interest in artificially recharging selected shallow sands in South Louisiana with fresh water has been stimulated by the desire to retard contamination of municipal groundwater supplies by brackish water, to retard ground subsidence and decrease pumping lifts, and to develop emergency subsurface supplies of potable water for communities dependent on surface waters susceptible to contamination. Results of field experiments, laboratory work, and model calculations demonstrate that ion exchange reactions involving clays dispersed in aquifer sands can be expected to modify significantly the composition of waters injected into Gulf Coast sediments. As little as 0.1 weight percent smectite (montmorillonite) can remove, by exchange with absorbed Na, a significant fraction of the dissolved Ca and Mg present in the injected water. The hardness of the water is thus reduced, which may be a desirable modification in water quality. Exchange occurs as fast as the fluids can be pumped into or out of the aquifer, and the water-softening capacity of the aquifer can be restored by allowing sodium-rich native pore waters to sweep back over the dispersed clays. Each acre of an aquifer 50 feet thick and containing 0.1 wt % smectite could soften half a million gallons of injected Mississippi River water. Many individual Gulf Coast aquifers underlie tens of thousands of acres, and their potential softening capacity is thus enormous. Additional exchange processes involving adjacent aquitard shales presumably will operate over long-term periods. It is possible that Gulf Coast aquifers will be used at some point in the future as processing plants to treat injected water to improve its quality for a variety of municipal and industrial purposes.

  15. Removal and Recovery of Chromium from Solutions Simulating Tannery Wastewater by Strong Acid Cation Exchanger

    Directory of Open Access Journals (Sweden)

    Gulten Cetin


    Full Text Available The process in this study was conducted on removal of chromium(III in a solution simulating a typical spent chrome tanning bath by the resin having matrix of styrene-divinylbenzene-based macroporous sulphonate, Amberjet 1200Na. The column experiments were carried out with the bed volumes of the resin as 751 mL and 1016 mL for different installation systems of the laboratory-scale pilot plant. The feeding solutions in the bed volumes of 200 and 190 were used for each installation system. The regeneration behaviour of the resin was determined by using reverse regeneration procedure with the solution of hydrogen peroxide in alkaline. The regeneration kinetics of the exhausted resin was examined with a range of the solutions having different concentration series of the alkaline hydrogen peroxide. The solutions of the basic chromium sulphate were recycled for each installation system following the regeneration cycles. The chromium ions in effluent were quantitatively eluted, and satisfactory removal of chromium(III and recovery of chromium(VI were achieved.

  16. Comparing the short and long term stability of biodegradable, ceramic and cation exchange membranes in microbial fuel cells. (United States)

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


    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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Effect of cation exchange resin treatment and addition on sugar as anti-caking agent on retention of nutritional and sensory quality of lemon juice powder during storage. (United States)

    Sharma, Satish K; Kaushal, B B L; Sharma, P C


    Lemon juices clarified with enzymatic treatment with and without cation exchange resin treatment were concentrated to 60(o) Brix in a vacuum evaporator and converted into powders by foam mat drying technique. Powders obtained from cation exchange resin treated juice were better in quality with respect to acidity, glucose, fructose, sugars, and ascorbic acid contents as compared to those prepared form non treated juice. Further, during 9 months storage, the powders suffered slight loss of acidity, and increase in reducing sugars i.e. glucose and fructose and considerable loss (31-55%) in vitamin C contents. Storage conditions did not bring about any significant change in the ash and hesperidin content of the product. But some losses were registered in the total phenols (23.69%) and sensory quality (from 7.72 to 7.26) of the powders. Further, the powders prepared from cation exchange resin treated juice and those pulverized with cane sugar suffered overall lesser changes in most of the quality parameters during 9 months of storage, thus indicating that, the treatment of lemon juice with cation exchange resin is beneficial for better initial product quality and pulverization of prepared powder with cane sugar is beneficial in reducing the hygroscopicity and retention of quality in a better way.

  18. Development of an on-line weak-cation exchange liquid chromatography-tandem mass spectrometric method for screening aldehyde products in biological matrices

    NARCIS (Netherlands)

    Eggink, M.; Charret, S.; Wijtmans, M.; Lingeman, H.; Kool, J.; Niessen, W.M.; Irth, H.


    This paper focuses on the development and optimization of an on-line weak-cation exchange SPE (WCXE) coupled to gradient HPLC with tandem MS detection. The system enables the selective purification and re-concentration of the in-vial derivatized aldehydes from plasma and urine samples. Aldehydes are

  19. 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.


    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...

  20. Effect of vapors of water and organic solvents on the luminescence of cation-exchange membranes immobilized with cyclometalated Pt(II) complexes (United States)

    Khakhalina, M. S.; Tikhomirova, I. Yu.; Puzyk, M. V.


    The luminescence quenching of cation-exchange membranes immobilized with cyclometalated Pt(II) complexes by vapors of water and some organic solvents (methanol, ethanol, isopropanol, n-butanol, acetonitrile, and acetone) is studied. The mechanism of the luminescence quenching of complexes is discussed.

  1. Evaluation of strong cation-exchange polymers for the determination of drugs by solid-phase extraction-liquid chromatography-tandem mass spectrometry. (United States)

    Fontanals, Núria; Miralles, Núria; Abdullah, Norhayati; Davies, Arlene; Gilart, Núria; Cormack, P A G


    This paper presents eight distinct strong cation-exchange resins, all of which were derived from precursor resins that had been synthesised using either precipitation polymerisation or non-aqueous dispersion polymerisation. The precursor resins were transformed into the corresponding strong cation-exchange resins by hypercrosslinking followed by polymer analogous reactions, to yield materials with high specific surface areas and strong cation-exchange character. These novel resins were then evaluated as strong cation-exchange (SCX) sorbents in the solid-phase extraction (SPE) of a group of drugs from aqueous samples. Following preliminary experiments, the two best-performing resins were then evaluated in solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE/LC-MS/MS) to determine a group of drugs from sewage samples. In general, use of these sorbents led to excellent recovery values (75-100%) for most of the target drugs and negligible matrix effects (ME) (<20% ion suppression/enhancement of the analyte signal), when 50mL and 25mL of effluent and influent sewage water samples, respectively, were percolated through the resins. Finally, a validated method based on SPE/LC-MS/MS was used to quantify the target drugs present in different sewage samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Removal of lead compounds from polyvinylchloride in electric wires and cables using cation-exchange resin. (United States)

    Tsunekawa, Masami; Ito, Mayumi; Yuta, Sasaki; Tomoo, Sakai; Hiroyoshi, Naoki


    Recycling treatment of cable insulation resin generated from electric wires and cables was investigated. Conventional insulation PVC contains a lead component, tribase, as a thermal stabilizer and lead removal is necessary to recycle this PVC as insulation resin. This paper describes a solid surface adsorption method using ion exchange resin to remove the fine lead containing particles from PVC dissolved solution. Low lead concentration in the recovered PVC, complying with the requirements of RoHS, was achieved. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. APLIKASI PENGOLAHAN POLUTAN ANION KHROM(VI DENGAN MENGGUNAKAN AGEN PENUKAR ION HYDROTALCIT ZN-AI-SO4 (Synthesis of and its Application to Treat Chrom(VI Pollutant Using Hydrotalcite Zn-Al_SO4 as Anion Exchanger

    Directory of Open Access Journals (Sweden)

    Roto Roto


    Full Text Available ABSTRAK Keberadaan logam khrom di dalam sistem perairan bersifat polutan yang harus ditangani dengan baik, dan untuk khrom (Vl yang sering dijumpai dalam bentuk anion dapat diolah dengan menggunakan mekanisme pertukaran ion. Suatu agen penukar anion telah dibuat berupa senyawa hidrotalsit Zn-Al-SOa melalui proses sintesis, karakterisasi serta dilakukan pula pengujian aplikasinya untuk pengurangan polutant anion khrom (VI dalam bentuk ion dikromat. Sintesis hidrotalsit Zn-Al-SOa dilakukan dengan metode stoikiometri pada pH 8 dan perlakuan hidrotermal. Aplikasi pertukaran dikromat dengan anion sulfat dalam antar lapis hidrotalsit serta uji regenerasi bahan diamati dengan bantuan analisis struktur dan analisis kinetika reaksi pertukaran. Produk pertukaran ion dikarakterisasi dengan XRD, spektrofotometri IR dan spektrometri serapan atom. Rumus kimia hidrotalsit produk diketahui adalah Zn0,74Al0,26(OH1,74(SO40,13.0,52H2O. Anion dikromat dapat menukar sulfat dalam antarlapis hidrotalsit yang ditunjukkan dalam spektra IR dan pola XRD. Kapasitas pertukaran anion untuk dikromat diketahui 216,84 mek/100 g, sedangkan kinetika reaksi pertukaran ion mengikuti orde dua dengan k = 3 x 10-8 ppm-1.detik-1. Hasil menunjukkan Zn-Al-Cr2O7 dapat mudah diregenerasi.    ABSTRACT  Chrom as pollutant in aquatics system usually establishes as crom (VI and should be worked with special treatment and as an example is ion exchanger. Material Zn-Al-SO4 hydrotalcite product have been synthesized and its application as anion exchanger for dichromate have been studied. Synthesis of Zn-Al-SO4 hydrotalcite was carried out by stoichiometric method at pH 8 and hydrothermal treatment. Sulphate in hydrotalcite interlayer was exchanged by dichromate. Kinetics of ion exchange was also investigated. The product of ion exchange was characterized by XRD, IR spectrophotometry and atomic adsorption  spectrometry. The chemical formula of the  hydrotalcite is Zn0.74Al0.26(OH1.74(SO4 0

  4. 3D Digital Mapping of Soil Cation Exchange Capacity in Dorud, Lorestan Province

    Directory of Open Access Journals (Sweden)

    R. Taghizadeh Mehrjerdi


    Full Text Available There is an increasing demand for reliable large-scale soil datato meet the requirements of models for planning of land-usesystems, characterization of soil pollution, and prediction ofland degradation. Cation exchangecapacity (CEC is among the most important soil propertiesthat are required in soil databases. This paper applied a novel method for whole-soil profile predictions of CEC (to 1 m across Dorudlocated in LorestanProvince. At present research, we combined equal-area spline depth functions with digital soil mapping techniques to predict the vertical and lateral variations of CEC across the study area where limited soil information exists (103 soil profiles. To model the relationship between CEC and environmental factors (i.e. Representative soil forming factors, derived from a digital elevation model and Landsat imagery, a regression tree was applied. Results indicated that some auxiliary data had more influence on the prediction model (i.e. B3 and modified catchment area. Our results also confirmed the regression tree model predicted target variable at the five specific depths with coefficient of determination of 0.84, 0.84, 0.84, 0.66, 0.27 and root mean square of 1.75, 1.84, 1.84, 2.11, and 2.16, respectively. Results showed a reasonable R2 in first four depths ranged from 0.66 to 0.84; while, it decreases to 0.27 in the last depth. Our results also confirmed that the regression tree as a predictive model, digital soil mappingtechniqueand equal area splinesare powerful tools to predict lateral and vertical variation of CEC.

  5. Uranium(VI adsorption on surfactant modified heulandite/clinoptilolite rich tuff

    Directory of Open Access Journals (Sweden)



    Full Text Available The adsorption of uranium(VI on heulandite/clinoptilolite rich zeolitic tuff modified with diferent amounts (2, 5 and 10 meq/100 g of hexadecyltrimethyl ammonium (HDTMA ion was investigated. The organozeolites were prepared by ion exchange of inorganic cations at the zeolite surface with HDTMA ions, and the three prepared samples were denoted as OA-2, OA-5 and OA-10. The maximal amount of HDTMAin the organozeolite OA-10 (10 meq/100 g was equal to the external cation exchange capacity of the starting material. The results showed that uranium( VI adsorption on unmodified zeolitic tuff was low (0.34 mg uranium(VI/g adsorbent, while for the organozeolites, the adsorption increased with increasing amount of HDTMA at the zeolitic surface. The highest adsorption indexes were achieved for the organozeolite OA-10, in which all the surface inorganic cations had been replaced with HDTMA. An investigation of the adsorption of uranium(VI ions onto organozeolite OA-10 at different pH values (3, 6 and 8 showed that the adsorption index increased with increasing amount of adsorbent in the suspension. Since uranium(VI speciation is highly dependent on pH, from the adsorption isotherms, it can be seen that uranium(VI adsorption on organozeolite OA-10 at pH 6 and 8 is well described by a Langmuir type of isotherm, while at pH 3, it corresponds to a Type III isotherm.

  6. Ionic liquids with amino acids as cations: novel chiral ligands in chiral ligand-exchange capillary electrophoresis. (United States)

    Mu, Xiaoyu; Qi, Li; Zhang, Haizhi; Shen, Ying; Qiao, Juan; Ma, Huimin


    Ionic liquids (ILs) with L-proline (L-Pro) as cations have been developed for the novel chiral ligands coordinated with Cu(II) in chiral ligand exchange capillary electrophoresis (CLE-CE). Four kinds of amino acid ionic liquids (AAILs), including [L-Pro][CF(3)COO], [L-Pro][NO(3)], [L-Pro][BF(4)] and [L-Pro(2)][SO(4)], were successfully synthesized. Among them, [L-Pro][CF(3)COO] was selected as the model ligand to optimize the separation conditions. The influences of AAIL concentration, pH, and methanol concentration on efficiency of chiral separation were investigated. Then it has been testified that the optimal buffer solution consisted of 25.0mM Cu(Ac)(2), 50.0 mM AAIL and 20% (v/v) methanol at pH 4.0. The interesting thing is well enantioresolution could be observed with [L-Pro][CF(3)COO] as the new chiral ligand and nine pairs of labeled D,L-AAs were successfully separated with the resolution ranging from 0.93 to 6.72. Meanwhile, the baseline separation of labeled D,L-AAs could be achieved with the other three kinds of AAILs as ligands. The results have demonstrated the good applicability of AAILs with AAs as cations for chiral separation in CLE-CE system. In addition, comparative study was also conducted for exploring the mechanism of the AAILs as new ligands in CLE-CE. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. A Characterization of Laponite Nanoclays by Dynamic Light Scattering, Scanning Electron Microscopy, and Cation Exchange Capacity by UV-Visible Spectroscopy (United States)

    Arnold, Randall

    Four different Laponite clays were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), and UV-Visible spectroscopy to determine the cation exchange capacity (CEC) to provide a methodology of analysis for other clays. DLS and SEM were utilized to observe the sizes, shape, and inter-particle interactions for the different clays. UV-Visible spectroscopy was implemented to characterize the CEC of each clay via a complexometric reaction with calcium. DLS provided limitedly consistent results due to a disparity in the translational diffusion of particles in suspension due to high aspect ratios and electroviscious forces; however, SEM provided high-resolution images of various particles and agglomerates with unique insight into the intra-particle edge-face, edge-edge, and face-face interactions driven by various electrochemical forces. The experimentally determined CECs, while consistently elevated above reported values, provide accurate first-pass estimations by a direct cation exchange methodology. Advancement of this work might include Mie scattering of angular dependence for DLS, as well as a correction for the electric double layer of the platelets; field emission SEM for microanalysis of single platelets and agglomerates; and using zeta potential to develop a methodology of observing stability and CEC of cation-loaded uncharacterized clays. Establishing a methodology for determining the CEC and cation loading provides the most valuable advancement towards characterizing other clays and linking cation loading to the zeta potential and colloidal stability.

  8. Simultaneous quantitative analysis of uremic toxins by LC-MS/MS with a reversed-phase/cation-exchange/anion-exchange tri-modal mixed-mode column. (United States)

    Kanemitsu, Yoshitomi; Asaji, Kei; Matsumoto, Yotaro; Tsukamoto, Hiroki; Saigusa, Daisuke; Mukawa, Chikahisa; Tachikawa, Tatsuki; Abe, Takaaki; Tomioka, Yoshihisa


    Column choice is crucial to the development of liquid chromatography/tandem mass spectrometry (LC-MS/MS) methods because analyte selectivity is dependent on the nature of the stationary phase. Recently, mixed-mode chromatography, which employs a combination of two or more stationary phases and solvent systems, has emerged as an alternative to multiple, complementary, single-column systems. This report describes the development and validation of a novel analytical method based on LC-MS/MS employing a reversed-phase/cation-exchange/anion-exchange tri-modal column (Scherzo SS-C18; Imtakt) for the simultaneous quantification of various uremic toxins (UTx), including creatinine, 1-methyladenosine, trimethylamine-N-oxide, indoxyl sulfate, p-cresyl sulfate, phenyl sulfate and 4-ethylphenyl sulfate. Stable isotope-labeled compounds were prepared as internal standards (ISs) for each analyte. Mobile phase optimization and appropriate gradient conditions resulted in satisfactory retention and peak resolution that could not have been attained with a single stationary phase LC system. The essential validation parameters, including intra- and inter-assay precision and accuracy, were adequate. The validated method was applied to measure serum levels of the aforementioned compounds in 19 patients with chronic kidney disease. This is the first report detailing the simultaneous quantification of these analytes using stable isotopes as ISs. Our results suggest that Scherzo SS-C18 columns will be considered breakthrough tools in the development of analytical methods for compounds that are difficult to quantify simultaneously in traditional LC systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Acute Hypocalcemia and Metabolic Alkalosis in Children on Cation-Exchange Resin Therapy

    Directory of Open Access Journals (Sweden)

    Aadil Kakajiwala


    Full Text Available Background. Sodium polystyrene sulfonate (SPS is a chelating agent used for the treatment of hyperkalemia. SPS has a wide range of exchange capacity requiring close monitoring of serum electrolytes. We observed two patients who developed acute hypocalcemia and increased metabolic alkalosis after initiating SPS therapy. We report these cases to draw attention to the potential risk of this medication in pediatric patients. Case Diagnosis/Treatment. Two children with chronic kidney disease on dialysis were started on SPS for hyperkalemia. Within a week after initiation of the medication, both patients developed hypocalcemia on routine labs without overt clinical manifestations. The hypocalcemia was rapidly corrected with oral supplementation and discontinuation of SPS. Conclusions. Severe hypocalcemia can develop after SPS therapy. The metabolic alkalosis in these patients associated with the hypocalcemia put them at increased risk for complications. Hence, careful attention must be paid to the state of calcium metabolism in all patients receiving SPS. Often calcium supplementation is required to maintain normal calcium levels.

  10. 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: [Department of Chemical and Biomolecular Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States)


    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.

  11. Formation of environmentally persistent free radical (EPFR) in iron(III) cation-exchanged smectite clay. (United States)

    Nwosu, Ugwumsinachi G; Roy, Amitava; dela Cruz, Albert Leo N; Dellinger, Barry; Cook, Robert


    Environmentally persistent free radicals (EPFRs) have been found at a number of Superfund sites, with EPFRs being formed via a proposed redox process at ambient environmental conditions. The possibility of such a redox process taking place at ambient environmental conditions is studied utilizing a surrogate soil system of phenol and iron(III)-exchanged calcium montmorillonite clay, Fe(III)CaM. Sorption of phenol by the Fe(III)CaM is demonstrated by Fourier-transformed infra-red (FT-IR) spectroscopy, as evidenced by the peaks between 1345 cm(-1) and 1595 cm(-1), and at lower frequencies between 694 cm(-1) and 806 cm(-1), as well as X-ray diffraction (XRD) spectroscopy, as shown by an increase in interlayer spacing within Fe(III)CaM. The formation and characterization of the EPFRs is determined by electron paramagnetic resonance (EPR) spectroscopy, showing phenoxyl-type radical with a g-factor of 2.0034 and ΔHP-P of 6.1 G at an average concentration of 7.5 × 10(17) spins per g. EPFRs lifetime data are indicative of oxygen and water molecules being responsible for EPFR decay. The change in the oxidation state of the iron redox center is studied by X-ray absorption near-edge structure (XANES) spectroscopy, showing that 23% of the Fe(III) is reduced to Fe(II). X-ray photoemission spectroscopy (XPS) results confirm the XANES results. These findings, when combined with the EPFR concentration data, demonstrate that the stoichiometry of the EPFR formation under the conditions of this study is 1.5 × 10(-2) spins per Fe(II) atom.

  12. High sensitive detection method for protein by combining the magnetic separation with cation exchange based signal amplification. (United States)

    Xu, Jin; Zhang, Qian-Mei; Zhao, Dong-Xu; Liu, Ya-Ru; Chen, Ping; Lu, Gui-Hong; Xie, Hai-Yan


    PSA is a member of low abundance proteins and serves as a critical indicator of the development and therapy efficacy for prostate cancer. In this study, a facile and high sensitive method was developed for serum PSA detection by integrating the immunomagnetic separation and cation exchange based signal amplification. On the basis of nanoparticle preparation and immunoprobe construction, PSA in serum was captured, separated by the immunomagnetic probe and then interacted with the quantum dots (QDs) based immunofluorescence probe; Zn2+ inside QDs was replaced by Ag+ within seconds, after which fluorescence signal was amplified by Fluozin-3, the Zn2+ responsive dye. Under optimized conditions, low detection limit (1.56pg/mL), wide linear range (1.56-25ng/mL) and good repeatability (intra-coefficient variation=3.18%) were achieved, which is superior to commercialized ELISA kit. These results demonstrated the potential of our high sensitive method for PSA detection in clinical. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Esterification of oleic acid in a three-phase, fixed-bed reactor packed with a cation exchange resin catalyst. (United States)

    Son, Sung Mo; Kimura, Hiroko; Kusakabe, Katsuki


    Esterification of oleic acid was performed in a three-phase fixed-bed reactor with a cation exchange resin catalyst (Amberlyst-15) at high temperature, which was varied from 80 to 120 °C. The fatty acid methyl ester (FAME) yields in the fixed-bed reactor were increased with increases in the reaction temperature, methanol flow rate and bed height. Moreover, the FAME yields were higher than those obtained using a batch reactor due to an equilibrium shift toward the product that resulted from continuous evaporation of the produced water. In addition, there was no catalyst deactivation during the esterification of oleic acid. However, addition of sunflower oil to the oleic acid reduced the FAME yield obtained from simultaneous esterification and transesterification. The FAME yield was 97.5% at a reaction temperature of 100 °C in the fixed-bed with a height of 5 cm when the methanol and oleic acid feed rates were 8.6 and 9.0 mL/h, respectively. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Cation exchange capacity (Qv) estimation in shaly sand reservoirs: case studies in the Junggar Basin, northwest China (United States)

    Wang, Liang; Mao, Zhi-Qiang; Sun, Zhong-Chun; Luo, Xing-Ping; Deng, Ren-Shuang; Zhang, Ya-Hui; Ren, Bing


    Cation exchange capacity (Qv) is a key parameter in resistivity-based water saturation models of shaly sand reservoirs, and the accuracy of Qv calculation is crucial to the prediction of saturations of oil and gas. In this study, a theoretical expression of Qv in terms of shaly sand permeability (Kshaly-sand), total porosity (ϕt), and salinity of formation water (S) is deduced based on the capillary tube model and the physics volume model. Meanwhile, the classical Schlumberger-Doll research (SDR) model has been introduced to estimate Kshaly-sand. On this basis, a novel technique to estimate Qv from nuclear magnetic resonance (NMR) logs is proposed, and the corresponding model is also established, whose model parameters are calibrated by laboratory Qv and NMR measurements of 15 core samples from the Toutunhe formation of the Junggar Basin, northwest China. Based on the experimental data sets, this technique can be extended to reservoir conditions to estimate continuous Qv along the intervals. The processing results of field examples illustrate that the Qv calculated from field NMR logs are consistent with the analyzed results, with the absolute errors within the scope of  ±0.1 mmol cm-3 for the majority of core samples.

  15. Gamma-aminobutyric acid production using immobilized glutamate decarboxylase followed by downstream processing with cation exchange chromatography. (United States)

    Lee, Seungwoon; Ahn, Jungoh; Kim, Yeon-Gu; Jung, Joon-Ki; Lee, Hongweon; Lee, Eun Gyo


    We have developed a gamma-aminobutyric acid (GABA) production technique using his-tag mediated immobilization of Escherichia coli-derived glutamate decarboxylase (GAD), an enzyme that catalyzes the conversion of glutamate to GABA. The GAD was obtained at 1.43 g/L from GAD-overexpressed E. coli fermentation and consisted of 59.7% monomer, 29.2% dimer and 2.3% tetramer with a 97.6% soluble form of the total GAD. The harvested GAD was immobilized to metal affinity gel with an immobilization yield of 92%. Based on an investigation of specific enzyme activity and reaction characteristics, glutamic acid (GA) was chosen over monosodium glutamate (MSG) as a substrate for immobilized GAD, resulting in conversion of 2.17 M GABA in a 1 L reactor within 100 min. The immobilized enzymes retained 58.1% of their initial activities after ten consecutive uses. By using cation exchange chromatography followed by enzymatic conversion, GABA was separated from the residual substrate and leached GAD. As a consequence, the glutamic acid was mostly removed with no detectable GAD, while 91.2% of GABA was yielded in the purification step.

  16. Gamma-Aminobutyric Acid Production Using Immobilized Glutamate Decarboxylase Followed by Downstream Processing with Cation Exchange Chromatography

    Directory of Open Access Journals (Sweden)

    Hongweon Lee


    Full Text Available We have developed a gamma-aminobutyric acid (GABA production technique using his-tag mediated immobilization of Escherichia coli-derived glutamate decarboxylase (GAD, an enzyme that catalyzes the conversion of glutamate to GABA. The GAD was obtained at 1.43 g/L from GAD-overexpressed E. coli fermentation and consisted of 59.7% monomer, 29.2% dimer and 2.3% tetramer with a 97.6% soluble form of the total GAD. The harvested GAD was immobilized to metal affinity gel with an immobilization yield of 92%. Based on an investigation of specific enzyme activity and reaction characteristics, glutamic acid (GA was chosen over monosodium glutamate (MSG as a substrate for immobilized GAD, resulting in conversion of 2.17 M GABA in a 1 L reactor within 100 min. The immobilized enzymes retained 58.1% of their initial activities after ten consecutive uses. By using cation exchange chromatography followed by enzymatic conversion, GABA was separated from the residual substrate and leached GAD. As a consequence, the glutamic acid was mostly removed with no detectable GAD, while 91.2% of GABA was yielded in the purification step.

  17. Simplified in vitro refolding and purification of recombinant human granulocyte colony stimulating factor using protein folding cation exchange chromatography. (United States)

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


    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. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Jan Schwellenbach


    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.

  19. Nitrogen and chemical oxygen demand removal from septic tank wastewater in subsurface flow constructed wetlands: substrate (cation exchange capacity) effects. (United States)

    Collison, Robert S; Grismer, Mark E


    The current article focuses on chemical oxygen demand (COD) and nitrogen (ammonium and nitrate) removal performance from synthetic human wastewater as affected by different substrate rocks having a range of porosities and cation exchange capacities (CECs). The aggregates included lava rock, lightweight expanded shale, meta-basalt (control), and zeolite. The first three had CECs of 1 to 4 mequiv/100 gm, whereas the zeolite CEC was much greater (-80 mequiv/100 gm). Synthetic wastewater was gravity fed to each constructed wetland system, resulting in a 4-day retention time. Effluent samples were collected, and COD and nitrogen species concentrations measured regularly during four time periods from November 2008 through June 2009. Chemical oxygen demand and nitrogen removal fractions were not significantly different between the field and laboratory constructed wetland systems when corrected for temperature. Similarly, overall COD and nitrogen removal fractions were practically the same for the aggregate substrates. The important difference between aggregate effects was the zeolite's ammonia removal process, which was primarily by adsorption. The resulting single-stage nitrogen removal process may be an alternative to nitrification and denitrification that may realize significant cost savings in practice.

  20. A universal design of field-effect-tunable microfluidic ion diode based on a gating cation-exchange nanoporous membrane (United States)

    Liu, Weiyu; Ren, Yukun; Tao, Ye; Yao, Bobin; Liu, Ni; Wu, Qisheng


    Based on the continuum mechanics theory, we propose herein a universal design of microfluidic ionic diode based on external concentration polarization of a gating ion-selective medium embedded in the microfluidic network with four power terminals. This micro/nanofluidic hybrid chip employs a cation-exchange nanoporous membrane (CEM) coupled with both a control and output microfluidic channel. Under the action of a vertical electric field throughout the CEM, nanoscale surface conduction of excessive counterions within the charged nanopores is converted to the propagation of either enriched or depleted boundary toward the opposing electrode-terminal in phase with the electroconvective flow, thereby making an adjustment in the electrical conductance of output microchannel for achieving high-flux field-effect current control and diode functionality. Three basic working states, including the "on," "transition," and "off" statuses, are distinguished in different ranges of source voltage magnitude. The rectification factor of the proposed ionic circuit platform can attain one hundred-fold even at small source and gate voltages. The presented field-effect-tunable microfluidic ion diode is easily scalable, permits appreciable fluid flow due to an intrinsically small hydrodynamic resistance, and holds promise for producing high-flux ion current rectification in next-generation integrated circuits.

  1. Evaluation of strong cation exchange versus isoelectric focusing of peptides for multidimensional liquid chromatography-tandem mass spectrometry. (United States)

    Slebos, Robbert J C; Brock, Jonathan W C; Winters, Nancy F; Stuart, Sarah R; Martinez, Misti A; Li, Ming; Chambers, Mathew C; Zimmerman, Lisa J; Ham, Amy J; Tabb, David L; Liebler, Daniel C


    Shotgun proteome analysis platforms based on multidimensional liquid chromatography-tandem mass spectrometry (LC-MS/MS) provide a powerful means to discover biomarker candidates in tissue specimens. Analysis platforms must balance sensitivity for peptide detection, reproducibility of detected peptide inventories and analytical throughput for protein amounts commonly present in tissue biospecimens (cation exchange (SCX) and isoelectric focusing (IEF) separations of peptides prior to LC-MS/MS analysis on a LTQ-Orbitrap hybrid instrument. IEF separations provided superior reproducibility and resolution for peptide fractionation from samples corresponding to both large (100 microg) and small (10 microg) protein inputs. SCX generated more peptide and protein identifications than did IEF with small (10 microg) samples, whereas the two platforms yielded similar numbers of identifications with large (100 microg) samples. In nine replicate analyses of tryptic peptides from 50 microg colon adenocarcinoma protein, overlap in protein detection by the two platforms was 77% of all proteins detected by both methods combined. IEF more quickly approached maximal detection, with 90% of IEF-detectable medium abundance proteins (those detected with a total of 3-4 peptides) detected within three replicate analyses. In contrast, the SCX platform required six replicates to detect 90% of SCX-detectable medium abundance proteins. High reproducibility and efficient resolution of IEF peptide separations make the IEF platform superior to the SCX platform for biomarker discovery via shotgun proteomic analyses of tissue specimens.

  2. Evaluation of ion exchange-modified Y and ZSM5 zeolites in Cr(VI) biosorption and catalytic oxidation of ethyl acetate


    Silva, Bruna Andreia Nogueira Airosa; Figueiredo, Hugo; Soares, O. S. G. P.; Pereira, M. de F. R.; Figueiredo, J.L.; Lewandowska, A. E.; Bañares, M. A.; Neves, I.C.; Tavares,M. T.


    The aim of this work was the evaluation of the performance of two zeolites with different structures (FAU and MFI) and acidity properties in the biosorption of Cr(VI) and catalytic oxidation of ethyl acetate. The starting zeolites, Y (FAU) and ZSM5 (MFI), were modified by ion exchange treatments with NaNO3 in order to obtain zeolites with different acidity and sodium content. A biosorption system consisting of a bacterium, Arthrobacter viscosus, supported on the different zeolites was used fo...

  3. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

    Directory of Open Access Journals (Sweden)

    César A. C. Sequeira


    Full Text Available Direct borohydride fuel cells (DBFC, which operate on sodium borohydride (NaBH4 as the fuel, and hydrogen peroxide (H2O2 as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S and a cation-exchange membrane (CMI-7000S, are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

  4. Application of mixed-mode, solid-phase extraction in environmental and clinical chemistry. Combining hydrogen-bonding, cation-exchange and Van der Waals interactions (United States)

    Mills, M.S.; Thurman, E.M.; Pedersen, M.J.


    Silica- and styrene-divinylbenzene-based mixed-mode resins that contain C8, C18 and sulphonated cation-exchange groups were compared for their efficiency in isolation of neutral triazine compounds from water and of the basic drug, benzoylecgonine, from urine. The triazine compounds were isolated by a combination of Van der Waals and hydrogen-bonding interactions, and benzoylecgonine was isolated by Van der Waals interactions and cation exchange. All analytes were eluted with a polar organic solvent contaning 2% ammonium hydroxide. Larger recoveries (95%) were achieved on copolymerized mixed-mode resins where C18 and sulfonic acid are in closer proximity than on 'blended' mixed-mode resins (60-70% recovery).

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


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


    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...

  6. Rational methods for predicting human monoclonal antibodies retention in protein A affinity chromatography and cation exchange chromatography. Structure-based chromatography design for monoclonal antibodies. (United States)

    Ishihara, Takashi; Kadoya, Toshihiko; Yoshida, Hideaki; Tamada, Taro; Yamamoto, Shuichi


    Rational methods for predicting the chromatographic behavior of human monoclonal antibodies (hMabs) in protein A affinity chromatography and cation exchange chromatography from the amino acid sequences information were proposed. We investigated the relation between the structures of 28 hMabs and their chromatographic behavior in protein A affinity chromatography and cation exchange chromatography using linear gradient elution experiments. In protein A affinity chromatography, the elution pH of the hMabs was correlated with not only the structure of the Fc region (subclass), but also that of the variable region. The elution pH of hMabs that have LYLQMNSL sequences in between the CDR2 and CDR3 regions of the heavy chain became lower among the same subclass of hMabs. In cation exchange chromatography, the peak salt concentrations IR of hMabs that have the same sequences of variable regions (or that have a structural difference in their Fc region, which puts them into a subclass) were similar. The IR values of hMabs were well correlated with the equilibrium association constant Ke, and also with the surface positive charge distribution of the variable region of the heavy chain (corrected surface net positive charge (cN) of the VH region). Based on these findings, we developed rational methods for predicting the retention behavior, which were also tested with eight additional hMabs. By considering the information on the number of binding sites associated with protein adsorption as determined experimentally, and the surface positive charge distribution from the three-dimensional structure of Mab A, we hypothesized that hMabs is separated by cation exchange chromatography as the surface positive charge distribution of the VH region is recognized.

  7. 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: [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)


    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.

  8. Preparation of a monolithic cation-exchange material with hydrophilic external layers by two-step reversible addition-fragmentation chain transfer polymerization. (United States)

    Lin, Shen; Zhang, Yingying; Huang, Wei; Dong, Xiangchao


    In recent years, the efficient analysis of biological samples has become more important due to the advances of life science and pharmaceutical research and practice. Because biological sample pretreatment is the bottleneck for fast process, material development for efficient sample process in the high-performance liquid chromatography analysis is highly desirable. In this research, a cation-exchange restricted access monolithic column was synthesized by a reversible addition-fragmentation chain transfer polymerization method. Utilizing the controlled/living property of the reversible addition-fragmentation chain transfer method, a monolithic column of cross-linked poly(sulfopropyl methacrylate) was prepared first and then linear poly(glycerol mono-methacrylate) was immobilized covalently on the surface of the polymer. The monolithic material has both functionalities of cation-exchange and protein exclusion. Protein recovery of 94.6% was obtained after grafting of poly(glycerol mono-methacrylate) while the cation-exchange property of the column is still retained. In the study, the relation between the synthetic conditions and properties of the materials was studied. The synthesis conditions including the porogen, monomer concentration, and ratio of monomers/initiator/reversible addition-fragmentation chain transfer agent were optimized. The study provided a method for the preparation of restricted access monolithic columns: a bifunctional material by reversible addition-fragmentation chain transfer polymerization method. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. 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.


    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.

  10. The effect of geometrical presentation of multimodal cation-exchange ligands on selective recognition of hydrophobic regions on protein surfaces. (United States)

    Woo, James; Parimal, Siddharth; Brown, Matthew R; Heden, Ryan; Cramer, Steven M


    The effects of spatial organization of hydrophobic and charged moieties on multimodal (MM) cation-exchange ligands were examined by studying protein retention behavior on two commercial chromatographic media, Capto™ MMC and Nuvia™ cPrime™. Proteins with extended regions of surface-exposed aliphatic residues were found to have enhanced retention on the Capto MMC system as compared to the Nuvia cPrime resin. The results further indicated that while the Nuvia cPrime ligand had a strong preference for interactions with aromatic groups, the Capto MMC ligand appeared to interact with both aliphatic and aromatic clusters on the protein surfaces. These observations were formalized into a new set of protein surface property descriptors, which quantified the local distribution of electrostatic and hydrophobic potentials as well as distinguishing between aromatic and aliphatic properties. Using these descriptors, high-performing quantitative structure-activity relationship (QSAR) models (R(2)>0.88) were generated for both the Capto MMC and Nuvia cPrime datasets at pH 5 and pH 6. Descriptors of electrostatic properties were generally common across the four models; however both Capto MMC models included descriptors that quantified regions of aliphatic-based hydrophobicity in addition to aromatic descriptors. Retention was generally reduced by lowering the ligand densities on both MM resins. Notably, elution order was largely unaffected by the change in surface density, but smaller and more aliphatic proteins tended to be more affected by this drop in ligand density. This suggests that modulating the exposure, shape and density of the hydrophobic moieties in multimodal chromatographic systems can alter the preference for surface exposed aliphatic or aromatic residues, thus providing an additional dimension for modulating the selectivity of MM protein separation systems. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. The grapevine VvCAX3 is a cation/H+ exchanger involved in vacuolar Ca2+ homeostasis. (United States)

    Martins, Viviana; Carneiro, Filipa; Conde, Carlos; Sottomayor, Mariana; Gerós, Hernâni


    The grapevine VvCAX3 mediates calcium transport in the vacuole and is mostly expressed in green grape berries and upregulated by Ca 2+ , Na + and methyl jasmonate. Calcium is an essential plant nutrient with important regulatory and structural roles in the berries of grapevine (Vitis vinifera L.). On the other hand, the proton-cation exchanger CAX proteins have been shown to impact Ca2+ homeostasis with important consequences for fruit integrity and resistance to biotic/abiotic stress. Here, the CAX gene found in transcriptomic databases as having one of the highest expressions in grapevine tissues, VvCAX3, was cloned and functionally characterized. Heterologous expression in yeast showed that a truncated version of VvCAX3 lacking its NNR autoinhibitory domain (sCAX3) restored the ability of the yeast strain to grow in 100-200 mM Ca2+, demonstrating a role in Ca2+ transport. The truncated VvCAX3 was further shown to be involved in the transport of Na+, Li+, Mn2+ and Cu2+ in yeast cells. Subcellular localization studies using fluorescently tagged proteins confirmed VvCAX3 as a tonoplast transporter. VvCAX3 is expressed in grapevine stems, leaves, roots, and berries, especially at pea size, decreasing gradually throughout development, in parallel with the pattern of calcium accumulation in the fruit. The transcript abundance of VvCAX3 was shown to be regulated by methyl jasmonate (MeJA), Ca2+, and Na+ in grape cell suspensions, and the VvCAX3 promotor contains several predicted cis-acting elements related to developmental and stress response processes. As a whole, the results obtained add new insights on the mechanisms involved in calcium homeostasis and intracellular compartmentation in grapevine, and indicate that VvCAX3 may be an interesting target towards the development of strategies for enhancement of grape berry properties.

  12. Micron-sized polymer particles from tanzanian cashew nut shell liquid. Part I: Preparation, functionalization with chloroacetic acid and utilization as cation exchange resin

    Directory of Open Access Journals (Sweden)

    O.O. Ilomo


    Full Text Available Micron-sized polymer particles (MSPP were prepared by formaldehyde condensation polymerization of cashew nut shell liquid (CNSL previously emulsified with sodium lauryl sulphate. The sizes of the MSPP were found to range from 0.1 to 4.4 μm. Increasing the emulsifier concentration had the effect of increasing the average particle size as well as the rate of polymerization. On the other hand, the polymerization rate decreased as the amount of the catalyst (sodium hydroxide increased. The MSPP were also found to be insoluble and stable in many organic solvents and in some inorganic reagents. The average number of surface OH groups was found to be 2.29 x 1018 per milligram of polymer particles. Micron-sized carboxylated cation exchange resins (MCCER were obtained by treating MSPP with monochloroacetic acid in an alkaline medium. The MCCER were found to exchange up to about 86 mg of calcium ion per gram of polymer at 30 ºC while the MSPP could exchange up to only about 6 mg of calcium ion per gram of polymer, at the same temperature. Compared to MSPP, the MCCER showed more than a thirteen-fold improvement in cation exchange capacity.

  13. Ion-exclusion/cation-exchange chromatography with dual detection of the conductivity and spectrophotometry for the simultaneous determination of common inorganic anionic species and cations in river and wastewater. (United States)

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


    Simultaneous determinations of common inorganic anionic species (SO(4)(2-), Cl(-), NO(3)(-), phosphate and silicate) and cations (Na(+), NH(4)(+), K(+), Mg(2+) and Ca(2+)) were conducted using an ion-chromatography system with dual detection of conductivity and spectrophotometry in tandem. The separation of ionic species on a weakly acidic cation-exchange resin was accomplished using a mixture of 100 mM ascorbic acid and 4 mM 18-crown-6 as an acidic eluent (pH 2.6), after which the ions were detected using a conductivity detector. Subsequently, phosphate and silicate were analyzed based on derivatization with molybdate and spectrophotometry at 700 nm. The detection limits at S/N = 3 ranged from 0.11 to 2.9 µM for analyte ionic species. This method was applied to practical river water and wastewater with acceptable criteria for the anion-cation balance and comparisons of the measured and calculated electrical conductivity, demonstrating the usefulness of the present method for water quality monitoring.

  14. Near-Infrared Emitting CuInSe2/CuInS2 Dot Core/Rod Shell Heteronanorods by Sequential Cation Exchange (United States)


    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-extracting agent. In this way, Cu+ ions can be extracted by trioctylphosphine ligands only when the In–P bond is broken. This results in readily available In3+ ions at the same surface site from which the Cu+ is extracted, making the process a direct place exchange reaction and shifting the overall energy balance in favor of the CE. Consequently, controlled cation exchange can occur even in large and anisotropic heterostructured nanocrystals with preservation of the size, shape, and heterostructuring of the template NCs into the product NCs. The cation exchange is self-limited, stopping when the ternary core/shell CuInSe2/CuInS2 composition is reached. The method is very versatile, successfully yielding a variety of luminescent CuInX2 (X = S, Se, and Te) quantum dots, nanorods, and HNCs, by using Cd-chalcogenide NCs and HNCs as templates. The approach reported here thus opens up routes toward materials with unprecedented properties, which would otherwise remain inaccessible. PMID:26449673

  15. Integrated SDS removal and peptide separation by strong-cation exchange liquid chromatography for SDS-assisted shotgun proteome analysis. (United States)

    Sun, Difei; Wang, Nan; Li, Liang


    We report an improved shotgun method for analyzing proteomic samples containing sodium dodecyl sulfate (SDS). This method is based on the use of strong-cation exchange (SCX) liquid chromatography (LC) for SDS removal that can be integrated with peptide separation as the first dimension of the two-dimensional LC tandem mass spectrometry workflow. To optimize the performance of SDS removal, various experimental conditions, including the concentrations of chemical reagents and salts in the sample, the SDS concentration, and the SCX mobile phase composition, were investigated. It was found that a peptide recovery rate of about 90% could be achieved while removing SDS efficiently. One key finding was that, by increasing the SDS concentration to a certain level (0.5%) in the digested peptide sample, the sample recovery rate could be increased. The peptide recovery rate of BSA digests was found to be 90.6 ± 1.0% (n = 3), and SDS in the SCX fractions collected was not detectable by pyrolysis GC-MS, i.e., below the detection limit of 0.00006% for the undesalted SCX fractions. The peptide recovery rates were found to be 90.9% ± 2.7 (n = 3) and 89.5% ± 0.5% (n = 3) for the digests of the membrane-protein-enriched fractions of E. coli cell lysates and the MCF-7 breast cancer cell line, respectively. Compared to the methods that use acid-labile surfactants, such as RapiGest and PPS, for the MCF-7 membrane fraction sample, the SDS method identified, on average (n = 3), more peptides (∼5%) and proteins (∼16%) than the RapiGest method, while the RapiGest method identified more peptides (∼21%) and proteins (∼7%) from the E. coli membrane fraction than the SDS method. In both cases, the two methods identified more peptides and proteins than the PPS method. Since SCX is widely used as the first dimension of 2D-LC MS/MS, integration of SDS removal with peptide separation in SCX does not add any extra steps to the sample handling process. We demonstrated the application of

  16. Insights in understanding aggregate formation and dissociation in cation exchange chromatography for a structurally unstable Fc-fusion protein. (United States)

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


    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

  17. 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:


    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)

  18. Enrichment and low-level determination of glyphosate, aminomethylphosphonic acid and glufosinate in drinking water after cleanup by cation exchange resin. (United States)

    Küsters, Markus; Gerhartz, Michael


    For the determination of glyphosate, aminomethylphosphonic acid and glufosinate in drinking water, different procedures of enrichment and cleanup were examined using anion exchange or SPE. In many cases interactions of, e.g. alkaline earth metal ions especially calcium could be observed during enrichment and cleanup resulting in loss of analytes. For that reason, a novel cleanup and enrichment procedure for the determination of these phosphonic acid herbicides has been developed in drinking water using cation-exchange resin. In summary, the cleanup procedure with cation-exchange resin developed in this study avoids interactions as described above and is applicable to calcium-rich drinking water samples. After derivatization with 9-fluorenylmethylchloroformate followed by LC with fluorescence detection, LOD of 12, 14 and 12 ng/L and mean recoveries from real-world drinking water samples of 98+/-9, 100+/-16 and 101+/-11% were obtained for glyphosate, aminomethylphosphonic acid and glufosinate, respectively. The low LODs and the high precision permit the analysis of these phosphonic acid herbicides according to the guidelines of the European Commission.

  19. Hybrid organic-inorganic silica monolith with hydrophobic/strong cation-exchange functional groups as a sorbent for micro-solid phase extraction. (United States)

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


    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%.

  20. Variation in whole DNA methylation in red maple (Acer rubrum) populations from a mining region: association with metal contamination and cation exchange capacity (CEC) in podzolic soils. (United States)

    Kalubi, K N; Mehes-Smith, M; Spiers, G; Omri, A


    Although a number of publications have provided convincing evidence that abiotic stresses such as drought and high salinity are involved in DNA methylation reports on the effects of metal contamination, pH, and cation exchange on DNA modifications are limited. The main objective of the present study is to determine the relationship between metal contamination and Cation exchange capacity (CEC) on whole DNA modifications. Metal analysis confirms that nickel and copper are the main contaminants in sampled sites within the Greater Sudbury Region (Ontario, Canada) and liming has increased soil pH significantly even after 30 years following dolomitic limestone applications. The estimated CEC values varied significantly among sites, ranging between 1.8 and 10.5 cmol(+) kg -1 , with a strong relationship being observed between CEC and pH (r = 0.96**). Cation exchange capacity, significantly lower in highly metal contaminated sites compared to both reference and less contaminated sites, was higher in the higher organic matter limed compared to unlimed sites. There was a significant variation in the level of cytosine methylation among the metal-contaminated sites. Significant and strong negative correlations between [5mdC]/[dG] and bioavailable nickel (r = -0.71**) or copper (r = -0.72**) contents were observed. The analysis of genomic DNA for adenine methylation in this study showed a very low level of [6N-mdA]/dT] in Acer rubrum plants analyzed ranging from 0 to 0.08%. Significant and very strong positive correlation was observed between [6N-mdA]/dT] and soil bioavailable nickel (r = 0.78**) and copper (r = 0.88**) content. This suggests that the increased bioavailable metal levels associated with contamination by nickel and copper particulates are associated with cytosine and adenine methylation.

  1. The role of nonmagnetic d{sup 0} vs. d{sup 10}B-type cations on the magnetic exchange interactions in osmium double perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Hai L., E-mail: [Max Planck Institute for Chemical Physics of Solids, Dresden 01187 (Germany); Yamaura, Kazunari [Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Tjeng, Liu Hao [Max Planck Institute for Chemical Physics of Solids, Dresden 01187 (Germany); Jansen, Martin, E-mail: [Max Planck Institute for Chemical Physics of Solids, Dresden 01187 (Germany); Max Planck Institute for Solid State Research, Stuttgart 70569 (Germany)


    Polycrystalline samples of double perovskites Ba{sub 2}BOsO{sub 6} (B=Sc, Y, In) were synthesized by solid state reactions. They adopt the cubic double perovskite structures (space group, Fm-3m) with ordered B and Os arrangements. Ba{sub 2}BOsO{sub 6} (B=Sc, Y, In) show antiferromagnetic transitions at 93 K, 69 K, and 28 K, respectively. The Weiss-temperatures are −590 K for Ba{sub 2}ScOsO{sub 6}, −571 K for Ba{sub 2}YOsO{sub 6}, and −155 K for Ba{sub 2}InOsO{sub 6}. Sc{sup 3+} and Y{sup 3+} have the open-shell d{sup 0} electronic configuration, while In{sup 3+} has the closed-shell d{sup 10}. This indicates that a d{sup 0} B-type cation induces stronger overall magnetic exchange interactions in comparison to a d{sup 10}. Comparison of Ba{sub 2}BOsO{sub 6} (B=Sc, Y, In) to their Sr and Ca analogues shows that the structural distortions weaken the overall magnetic exchange interactions. - Graphical abstract: Magnetic properties of osmium double perovskites Ba{sub 2}BOsO{sub 6} (B=Sc, Y, In) were studied. Comparison of Ba{sub 2}BOsO{sub 6}indicates that a d{sup 0} B-type cation induces stronger overall magnetic exchange interactions in comparison to a d{sup 10}. - Highlights: • Magnetic properties of double perovskites Ba{sub 2}BOsO{sub 6} (B=Sc, Y, In) were studied. • A d{sup 0}B-type cation induces stronger magnetic interactions than a d{sup 10}. • Structural distortions weaken the overall Os{sup 5+}-Os{sup 5+} magnetic interactions.

  2. Evaluation of high-capacity cation exchange chromatography for direct capture of monoclonal antibodies from high-titer cell culture processes. (United States)

    Tao, Yinying; Ibraheem, Aladein; Conley, Lynn; Cecchini, Douglas; Ghose, Sanchayita


    Advances in molecular biology and cell culture technology have led to monoclonal antibody titers in excess of 10 g/L. Such an increase can pose concern to traditional antibody purification processes due to limitations in column hardware and binding capacity of Protein A resins. Recent development of high capacity cation exchangers can make cation exchange chromatography (CEX) a promising and economic alternative to Protein A capture. This work investigates the feasibility of using CEX for direct capture of monoclonal antibodies from high titer cell culture fluids. Two resin candidates were selected from seven newer generation cation exchangers for their higher binding capacity and selectivity. Two monoclonal antibodies with widely differing pI values were used to evaluate the capability of CEX as a platform capture step. Screening of loading pH and conductivity showed both resins to be capable of directly capturing both antibodies from undiluted cell culture fluid. At appropriate acidic pH range, product loading of over 65 g/L resin was achieved for both antibodies. A systematic design of experiment (DOE) approach was used to optimize the elution conditions for the CEX step. Elution pH showed the most significant impact on clearance of host cell proteins (HCPs). Under optimal conditions, HCP reduction factors in the range of 9-44 were achieved on the CEX step based on the pI of the antibody. Apart from comparing CEX directly to Protein A as the capture method, material from either modality was also processed through the subsequent polishing steps to compare product quality at the drug substance level. Process performance and product quality was found to be acceptable using the non-affinity based process scheme. The results shown here present a cheaper and higher capacity generic capture method for high-titer antibody processes. © 2014 Wiley Periodicals, Inc.

  3. Separation of aliphatic carboxylic acids and benzenecarboxylic acids by ion-exclusion chromatography with various cation-exchange resin columns and sulfuric acid as eluent. (United States)

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


    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.

  4. Evidence of exchange interaction of localized carriers and transition metals in diluted II-VI nanostructures : ODMR study

    NARCIS (Netherlands)

    Baranov, P. G.; Romanov, N. G.; Tolmachev, D. O.; Gurin, A. S.; Namozov, B. R.; Kusrayev, Yu G.; Karczewski, G.; Orlinskii, S.; De Mello Donega, C.; Schmidt, J.


    Optically detected magnetic resonance study of (CdMn)Te/(CdMg)Te quantum wells allowed to reveal the formation of exchange-coupled complexes consisting of Mn ions and localized holes in quantum wells with excess hole concentration and the directional electron tunneling towards wider wells in

  5. Cation Exchange Combined with Kirkendall Effect in the Preparation of SnTe/CdTe and CdTe/SnTe Core/Shell Nanocrystals. (United States)

    Jang, Youngjin; Yanover, Diana; Čapek, Richard Karel; Shapiro, Arthur; Grumbach, Nathan; Kauffmann, Yaron; Sashchiuk, Aldona; Lifshitz, Efrat


    Controlling the synthesis of narrow band gap semiconductor nanocrystals (NCs) with a high-quality surface is of prime importance for scientific and technological interests. This Letter presents facile solution-phase syntheses of SnTe NCs and their corresponding core/shell heterostructures. Here, we synthesized monodisperse and highly crystalline SnTe NCs by employing an inexpensive, nontoxic precursor, SnCl2, the reactivity of which was enhanced by adding a reducing agent, 1,2-hexadecanediol. Moreover, we developed a synthesis procedure for the formation of SnTe-based core/shell NCs by combining the cation exchange and the Kirkendall effect. The cation exchange of Sn(2+) by Cd(2+) at the surface allowed primarily the formation of SnTe/CdTe core/shell NCs. Further continuation of the reaction promoted an intensive diffusion of the Cd(2+) ions, which via the Kirkendall effect led to the formation of the inverted CdTe/SnTe core/shell NCs.

  6. 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


    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.

  7. Improved plasma free metadrenaline analysis requires mixed mode cation exchange solid-phase extraction prior to liquid chromatography tandem mass spectrometry detection. (United States)

    Clarke, Michael W; Cooke, Brian; Hoad, Kirsten; Glendenning, Paul


    The investigation and effective management of phaeochromocytoma involves biochemical measurement of either conjugated total urine or plasma free metadrenalines. Current analytical methods include enzyme-linked immunosorbent assays, high-performance liquid chromatography (HPLC) with electrochemical detection (ECD) or liquid chromatography tandem mass spectrometry (LCMS/MS). Since the first two methods are either extremely laborious, necessitate low sample run numbers, result in slow turnaround times or are subject to analytical interference, a robust, routine clinical method is not achievable. We established a novel sample preparation method to measure plasma free metadrenalines using LCMS/MS. Three different solid-phase extraction (SPE) methods were compared: hydrophilic-lipophilic balance sorbent (HLB), weak cation exchange (WCX) and mixed mode cation exchange (MCX) and their ability to remove interfering compounds prior to LCMS/MS analysis. Maximum recovery of plasma free metadrenaline and plasma free normetadrenaline were achieved by positively charging compounds prior to SPE application. Compared with HLB and WCX cartridges, MCX extraction resulted in chromatography without co-eluting interference with superior assay precision and accuracy. Additionally, samples that could not be quantified because of interference using HPLC/ECD could be readily assayed using this new method. The use of the MCX SPE method with LCMS/MS detection provides an improved assay to measure plasma free metadrenalines in comparison to many available alternative methods.

  8. Application of cation-exchange solid-phase extraction for the analysis of amino alcohols from water and human plasma for verification of Chemical Weapons Convention. (United States)

    Kanaujia, Pankaj K; Tak, Vijay; Pardasani, Deepak; Gupta, A K; Dubey, D K


    The analysis of nitrogen containing amino alcohols, which are the precursors and degradation products of nitrogen mustards and nerve agent VX, constitutes an important aspect for verifying the compliance to the CWC (Chemical Weapons Convention). This work devotes on the development of solid-phase extraction method using silica- and polymer-based SCX (strong cation-exchange) and MCX (mixed-mode strong cation-exchange) cartridges for N,N-dialkylaminoethane-2-ols and alkyl N,N-diethanolamines, from water. The extracted analytes were analyzed by GC-MS (gas chromatography-mass spectrometry) in the full scan and selected ion monitoring modes. The extraction efficiencies of SCX and MCX cartridges were compared, and results revealed that SCX performed better. Extraction parameters, such as loading capacity, extraction solvent, its volume, and washing solvent were optimized. Best recoveries were obtained using 2 mL methanol containing 10% NH(4)OH and limits of detection could be achieved up to 5 x 10(-3) microg mL(-1) in the selected ion monitoring mode and 0.01 microg mL(-1) in full scan mode. The method was successfully employed for the detection and identification of amino alcohol present in water sample sent by Organization for Prohibition of Chemical Weapons (OPCW) in the official proficiency tests. The method was also applied to extract the analytes from human plasma. The SCX cartridge showed good recoveries of amino alcohols from human plasma after protein precipitation.

  9. 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: [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)


    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.

  10. Selectivity control in synergistic liquid-liquid anion exchange of univalent anions via structure-specific cooperativity between quaternary ammonium cations and anion receptors. (United States)

    Borman, Christopher J; Bonnesen, Peter V; Moyer, Bruce A


    Two anion receptors enhance liquid-liquid anion exchange when added to quaternary alkylammonium chloride anion exchangers, but with a striking dependence on the structure of the alkylammonium cation that suggests a supramolecular cooperative effect. Two anion receptors were investigated, meso-octamethylcalix[4]pyrrole (C4P) and the bisthiourea tweezer 1,1'-(propane-1,3-diyl)bis(3-(4-sec-butylphenyl)thiourea (BTU). Whereas synergism is comparatively weak when either methyltri(C(8,10))alkylammonium chloride (Aliquat 336) or tetraheptylammonium chloride is used with the BTU receptor, synergism between C4P and Aliquat 336 is so pronounced that anion exchange prefers chloride over more extractable nitrate and trifluoroacetate, effectively overcoming the ubiquitous Hofmeister bias. A thermochemical analysis of synergistic anion exchange has been provided for the first time, resulting in the estimation of binding constants for C4P with the ion pairs of A336(+) with Cl(-), Br(-), OAc(F3)(-), NO(3)(-), and I(-).

  11. Microwave-assisted, grafting polymerization preparation of strong cation exchange nylon 6 capillary-channeled polymer fibers and their chromatographic properties. (United States)

    Jiang, Liuwei; Marcus, R Kenneth


    Native nylon 6 C-CP fibers were modified with 2-acrylamido-2-methylpropanesulfonic acid (AMPS) via the microwave-assisted grafting polymerization to affect a strong cation exchange stationary phase. Various concentrations of AMPS and the initiator potassium persulfate (KPS) were used in the modifications. The resultant nylon-SO3H fibers were characterized by Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM) and acid-base titrations. The chromatographic properties, including column permeability, protein separation quality, and protein binding capacity, of the nylon-SO3H fiber columns were also studied. The cation exchange ligand densities on the modified fibers (SO3H) were determined to be 50-317 μmol g(-1), in comparison to the cation (COOH) density of 28 μmol g(-1) of native nylon 6 fibers. The modified fiber phase showed increased lysozyme dynamic loading capacities (up to ∼13 mg mL(-1) bed volume) at a linear velocity of ∼90 cm min(-1), while native nylon 6 showed only ∼1 mg mL(-1) lysozyme loading capacity. Fast (30 s-3 min) gradient separations of myoglobin, α-chymotrypsinogen A, and lysozyme were achieved on nylon-SO3H columns, with the separation resolution and peak capacity characterized. The efficiency of surface re-equilibration was probed with an eye toward using the phase as the second dimension in comprehensive two-dimensional liquid chromatography (2D-LC). The results indicate that this nylon-SO3H fiber phase has a good deal of potential for use in high-throughput analytical and preparative protein separations. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Application of Brazilian kaolinite clay as adsorbent to removal of U(VI) from aqueous solution: Kinetic and thermodynamic of cation-basic interactions (United States)

    Guerra, Denis L.; Leidens, Victor L.; Viana, Rúbia R.; Airoldi, Claudio


    The compound N 1-[3-(trimethoxysilyl)propyl]diethylenetriamine was anchored onto Amazon kaolinite surface by heterogeneous route. The modified and natural kaolinite samples were characterized by transmission electron microscopy, scanning electron microscopic, X-ray diffraction, and nuclear magnetic nuclei of 29Si and 13C. The well-defined peaks obtained in the 13C NMR spectrum in the 5.0-62.1 ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The ability of these materials to remove U(VI) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0. The kinetic parameters analyzed by the Lagergren and Elovich models gave a good fit for a pseudo-second order reaction with k2 values 16.0 and 25.1 mmol g -1 min -1 ranges for natural and modified kaolinite clays, respectively. The energetic effects caused by metal ion adsorption were determined through calorimetric titrations.

  13. The effect of Sinabung volcanic ash and rock phosphate nanoparticle on CEC (cation exchange capacity) base saturation exchange (K, Na, Ca, Mg) and base saturation at Andisol soils Ciater, West Java (United States)

    Yuniarti, Anni; Arifin, Mahfud; Sofyan, Emma Trinurasi; Natalie, Betty; Sudirja, Rija; Dahliani, Dewi


    Andisol, soil orders which covers an upland area dominantly. The aim of this research is to know the effect between the ameliorant of Sinabung volcanic ashes with the ameliorant of rock phosphatenanoparticle towards CEC and base saturation exchange (K, Na, Ca, Mg) and the base saturation on Ciater's Andisols, West Java. A randomized complete block design (RCBD) factorial with two factors was used in this research. The first factor is the volcanic ash and the second factor is rock phosphate which consists of four levels each amount of 0%, 2.5%, 5%, 7.5% with three replications. The result showed that there was no interaction between volcanic ash and rock phosphate nanoparticle formed in first month and fourth month towards the improvement of CEC and saturation base exchange rate unless magnesium cation exchange increased in fourth month. There was independent effect of volcanic ash formed nanoparticles towards base saturation exchange increased for 5% dose. There was independent effect of rock phosphate formed nanoparticles towards base saturation exchange and increased for 5% dose. The dose combination of volcanic ashes 7.5% with phosphate rock, 5% increased the base saturation in the first month incubation.

  14. Dynamic equilibria in solvent-mediated anion, cation and ligand exchange in transition-metal coordination polymers: solid-state transfer or recrystallisation? (United States)

    Cui, Xianjin; Khlobystov, Andrei N; Chen, Xinyong; Marsh, Dan H; Blake, Alexander J; Lewis, William; Champness, Neil R; Roberts, Clive J; Schröder, Martin


    The solution properties of a series of transition-metal-ligand coordination polymers [ML(X)(n)](infinity) [M=Ag(I), Zn(II), Hg(II) and Cd(II); L=4,4'-bipyridine (4,4'-bipy), pyrazine (pyz), 3,4'-bipyridine (3,4'-bipy), 4-(10-(pyridin-4-yl)anthracen-9-yl)pyridine (anbp); X=NO(3) (-), CH(3)COO(-), CF(3)SO(3) (-), Cl(-), BF(4) (-); n=1 or 2] in the presence of competing anions, metal cations and ligands have been investigated systematically. Providing that the solubility of the starting complex is sufficiently high, all the components of the coordination polymer, namely the anion, the cation and the ligand, can be exchanged on contact with a solution phase of a competing component. The solubility of coordination polymers is a key factor in the analysis of their reactivity and this solubility depends strongly on the physical properties of the solvent and on its ability to bind metal cations constituting the backbone of the coordination polymer. The degree of reversibility of these solvent-induced anion-exchange transformations is determined by the ratio of the solubility product constants for the starting and resultant complexes, which in turn depend upon the choice of solvent and the temperature. The extent of anion exchange is controlled effectively by the ratio of the concentrations of incoming ions to outgoing ions in the liquid phase and the solvation of various constituent components comprising the coordination polymer. These observations can be rationalised in terms of a dynamic equilibrium of ion exchange reactions coupled with Ostwald ripening of crystalline products. The single-crystal X-ray structures of [Ag(pyz)ClO(4)](infinity) (1), {[Ag(4,4'-bipy)(CF(3)SO(3))]CH(3)CN}(infinity) (2), {[Ag(4,4'-bipy)(CH(3)CN)]ClO(4) 0.5 CH(3)CN}(infinity) (3), metal-free anbp (4), [Ag(anbp)NO(3)(H(2)O)](infinity) (5), {[Cd(4,4'-bipy)(2)(H(2)O)(2)](NO(3))(2)4 H(2)O}(infinity) (6) and {[Zn(4,4'-bipy)SO(4)(H(2)O)(3)] 2 H(2)O}(infinity) (7) are reported.

  15. Cátions trocáveis, capacidade de troca de cátions e saturação por bases em solos brasileiros adubados com composto de lixo urbano Exchangeable cations, cation exchange capacity and base saturation in Brazilian soils amended with urban waste compost

    Directory of Open Access Journals (Sweden)

    Cassio Hamilton Abreu Jr.


    Full Text Available O uso agrícola do composto de lixo, como fertilizante orgânico, além de melhorar as propriedades do solo, representa uma alternativa importante para gestão de resíduos sólidos domiciliares. Foram estudados os efeitos da aplicação do composto de lixo, proveniente da cidade de São Paulo (Usina de compostagem São Matheus, na dose de 30 g dm-3 (60 t ha-1, na presença e ausência de calcário dolomítico e adubos minerais, sobre os teores de cátions trocáveis (K+, Ca2+, Mg2+ e Na+; a capacidade de troca de cátions (CTC e a saturação por bases (V% de 21 solos ácidos e 5 solos alcalinos. Nos solos alcalinos o calcário foi substituído por gesso. O experimento foi conduzido em condições de casa de vegetação em delineamento em blocos ao acaso, com parcelas em faixas e três repetições. Nos solos ácidos, a aplicação do composto de lixo promoveu aumentos nos teores trocáveis de potássio, cálcio, magnésio e sódio, em média, de 195%, 200%, 86% e 1200%, e elevação da CTC em 42%, refletindo na V%, com aumento médio de 39%. Nos solos alcalinos, esses efeitos foram menos pronunciados, refletindo porém, em média, em aumentos da CTC em 8,4% e da V% em 2%. Os maiores efeitos sobre as propriedades químicas avaliadas foram conseqüências das aplicações do composto + adubo + calcário, nos solos ácidos, e do composto + adubo + gesso, nos solos alcalinos. A aplicação agrícola do composto de lixo urbano é viável, porém seus efeitos sobres as propriedades químicas do solo devem ser monitorados.The use of urban organic solid waste compost as organic fertilizer is an important alternative to solid waste management. This waste has been applied to agricultural lands because of the benefits in relation to soil chemical properties. A greenhouse experiment was conducted to investigate the effects of the application of urban waste compost, at the rate of 30 g dm-3 (60 t ha-1, on the contents of exchangeable cations (K+, Ca2+, Mg2

  16. Anion-directed assemblies of cationic metal-organic frameworks based on 4,4'-bis(1,2,4-triazole): syntheses, structures, luminescent and anion exchange properties. (United States)

    Li, Xinxiong; Gong, Yaqiong; Zhao, Huaixia; Wang, Ruihu


    Three cationic metal-organic frameworks (MOFs), Ag(btr)·PF6·0.5CH3CN (1), Ag2(btr)2(H2O)·2CF3SO3·H2O (2), and Ag2(btr)2(NO3)·NO3 (3), were prepared from reaction of 4,4'-bis(1,2,4-triazole) (btr) with silver salts containing different anions. Complex 1 is a three-dimensional (3-D) framework constructed from tetrahedral-shaped nanoscale coordination cages with PF6(-) as counteranions. 2 and 3 are 3-D architectures containing 1-D channels, in which charge-balancing CF3SO3(-) and NO3(-) are located in their respective channels. Luminescent emission of 1-3 shows an obvious red shift compared with the btr ligand. Anion exchange studies show that 1 is able to selectively exchange MnO4(-) in aqueous solution with a modest capacity of 0.56 mol mol(-1); the luminescent emission of 1 is quickly quenched upon MnO4(-) exchange.

  17. Sequential Determination of Total Arsenic and Cadmium in Concentrated Cadmium Sulphate Solutions by Flow-Through Stripping Chronopotentiometry after Online Cation Exchanger Separation

    Directory of Open Access Journals (Sweden)

    Frantisek Cacho


    Full Text Available Flow-through stripping chronopotentiometry with a gold wire electrode was used for the determination of total arsenic and cadmium in cadmium sulphate solutions for cadmium production. The analysis is based on the online separation of arsenic as arsenate anion from cadmium cations by means of a cation exchanger. On measuring arsenate in the effluent, the trapped cadmium is eluted by sodium chloride solution and determined in a small segment of the effluent by making use of the same electrode. The elaborated protocol enables a full automatic measurement of both species in the same sample solution. The accuracy of the results was confirmed by atomic absorption spectrometry. The LOD and LOQ for Arsenic were found to be 0.9 μg dm-3 and 2.7 μg dm-3, respectively. A linear response range was observed in the concentration range of 1 to 300 μg dm-3 for sample volumes of 4 mL. The repeatability and reproducibility were found to be 2.9% and 5.2%, respectively. The linear response range for cadmium was found to be 0.5 to 60 g/L. The method was tested on samples from a cadmium production plant.

  18. Synthesis of poly(arylene ether ketone)s bearing skeletal crown ether units for cation exchange membranes

    NARCIS (Netherlands)

    Zoetebier, Bram; Tas, Sinem; Vancso, Gyula J.; Nijmeijer, Dorothea C.; Hempenius, Mark A.


    Poly(arylene ether ketone)s (PAEKs) are the most commonly known high-performance materials used for ion exchange and fuel cell membranes. Described here is the design of novel sulfonated PAEKs (SPAEKs) and nonsulfonated PAEKs containing crown ether units in the main chain, which can be used in

  19. A two-layer ONIOM study of thiophene cracking catalyzed by proton- and cation-exchanged FAU zeolite. (United States)

    Sun, Yingxin; Mao, Xinfeng; Pei, Supeng


    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.

  20. 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


    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.

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

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


    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.

  2. Dowex anion exchanger-loaded-baker's yeast as bi-functionalized biosorbents for selective extraction of anionic and cationic mercury(II) species. (United States)

    Mahmoud, Mohamed E; Yakout, Amr A; Osman, Maher M


    Dowex anion exchanger-immobilized-baker's yeast [Dae-yeast] were synthesized and potentially applied as environmental friendly biosorbents to evaluate the up-take process of anionic and cationic mercury(II) species as well as other metal ions. Optimization of mass ratio of Dowex anion exchanger versus yeast (1:1-1:10) in presence of various interacting buffer solutions (pH 4.0-9.0) was performed and evaluated. Surface modification of [Dae-yeast] was characterized by scanning electron microscopy (SEM) and infrared spectroscopy. The maximum metal biosorption capacity values of [Dae-yeast] towards mercury(II) were found in the range of 0.800-0.960, 0.840-0.950 and 0.730-0.900 mmol g(-1) in presence of buffer solutions pH 2.0, 4.0 and 7.0, respectively. Three possible and different mechanisms are proposed to account for the biosorption of mercury and mercuric species under these three buffering conditions based on ion exchange, ion pair and chelation interaction processes. Factors affecting biosorption of mercury from aqueous medium including the pH effect of aqueous solutions (1.0-7.0), shaking time (1-30 min) and interfering ions were se arched. The potential applications of modified biosorbents for selective biosorption and extraction of mercury from different real matrices including dental filling waste materials, industrial waste water samples and mercury lamp waste materials were also explored. The results denote to excellent percentage extraction values, from nitric acid as the dissolution solvent with a pH 2.0, as determined in the range of 90.77-97.91+/-3.00-5.00%, 90.00-93.40+/-4.00-5.00% and 92.31-100.00+/-3.00-4.00% for the three tested samples, respectively.

  3. The critical relation between chemical stability of cations and water in anion exchange membrane fuel cells environment (United States)

    Dekel, Dario R.; Willdorf, Sapir; Ash, Uri; Amar, Michal; Pusara, Srdjan; Dhara, Shubhendu; Srebnik, Simcha; Diesendruck, Charles E.


    Anion exchange membrane fuel cells can potentially revolutionize energy storage and delivery; however, their commercial development is hampered by a significant technological impedance: the chemical decomposition of the anion exchange membranes during operation. The hydroxide anions, while transported from the cathode to the anode, attack the positively charged functional groups in the polymer membrane, neutralizing it and suppressing its anion-conducting capability. In recent years, several new quaternary ammonium salts have been proposed to address this challenge, but while they perform well in ex-situ chemical studies, their performance is very limited in real fuel cell studies. Here, we use experimental work, corroborated by molecular dynamics modeling to show that water concentration in the environment of the hydroxide anion, as well as temperature, significantly impact its reactivity. We compare different quaternary ammonium salts that have been previously studied and test their stabilities in the presence of relatively low hydroxide concentration in the presence of different amounts of solvating water molecules, as well as different temperatures. Remarkably, with the right amount of water and at low enough temperatures, even quaternary ammonium salts which are considered "unstable", present significantly improved lifetime.

  4. New low cost sorbents for Cr(VI – batch and column experiments

    Directory of Open Access Journals (Sweden)

    Šillerová H.


    Full Text Available The use of agricultural byproducts and industrial biowaste materials has been shown to be an attractive technique for removing Cr(VI from contaminated waste waters. In this study, used brewers draff, peat moss, sawdust, grape stalks and husks were investigated as novel biosorbents for Cr(VI. The material was tested in two different modifications. The material was dried, cut and sieved and part of it was subjected to acid (2 M H2SO4 and alkali (0.5 M NaOH pre-treatments to remove starch, proteins and sugars. Fourier transform infrared rays analysis on solid phase (FTIR-ATR was used to determine the main functional groups that might control the metal uptake. Batch experiments were performed at different pH values (3, 4.5, 6 and at various initial concentration of Cr(VI (25–2012;250 mg L−1. Two equilibrium empirical models, Langmuir and Freundlich, were used to describe Cr(VI adsorption. In order to identify possible reduction processes, ion exchange separation on the AG1-X8 resin was used to separate the anionic Cr(VI and the reduced cationic Cr(III from the aqueous phase after biosorption. As expected, Cr(VI removal was pH-dependent and fitted well both the Langmuir and Freundlich isotherm models. The ion exchange separation showed that Cr(VI reduction had occurred in the solution during biosorption. The efficiency of draff as a biosorbent was comparable (or even higher to highly organic materials (e.g., composted peat showing its potential application for Cr(VI decontamination.

  5. Understanding the reactivity and basicity of zeolites: a periodic DFT study of the disproportionation of N(2)O(4) on alkali-cation-exchanged zeolite Y. (United States)

    Mignon, Pierre; Pidko, Evgeny A; Van Santen, Rutger A; Geerlings, Paul; Schoonheydt, Robert A


    The disproportionation of N(2)O(4) into NO(3)(-) and NO(+) on Y zeolites has been studied through periodic DFT calculations to unravel 1) the role of metal cations and the framework oxygen atoms and 2) the relationship between the NO(+) stretching frequency and the basicity of zeolites. We have considered three situations: adsorption on site II cations with and without a cation at site III and adsorption on a site III cation. We observed that cations at sites II and III cooperate to stabilize N(2)O(4) and that the presence of a cation at site III is necessary to allow the disproportionation reaction. The strength of the stabilization is due to the number of stabilizing interactions increasing with the size of the cation and to the Lewis acidity of the alkali cations, which increases as the size of the cations decreases. In the product, NO(3)(-) interacts mainly with the cations and NO(+) with the basic oxygen atoms of the tetrahedral aluminium through its nitrogen atom. As the cation size increases, the NO(3)(-)...cation interaction increases. As a result, the negative charge of the framework is less well screened by the larger cations and the interaction between NO(+) and the basic oxygen atoms becomes stronger. NO(+) appears to be a good probe of zeolite basicity, in agreement with experimental observations.

  6. A new method for separation and determination of Cr(III) and Cr(VI) in water samples by high-performance liquid chromatography based on anion exchange stationary phase of ionic liquid modified silica. (United States)

    Sadeghi, Susan; Moghaddam, Ali Zeraatkar


    In this work, N-methylimidazolium-chloride ionic liquid functionalized silica was prepared and used as an anion-exchange stationary phase for separation of chromium species by high-performance liquid chromatography (HPLC) with UV detection at 200 nm. The Cr(VI) as HCr2O7(-) and chelated Cr(III) with potassium hydrogen phthalate (PHP) as Cr(PHP)2 (-) was retained on the prepared column and separated using a mobile phase composed of 5% methanol in 25 mM phosphate buffer at pH 6.5. Several variables affecting the chelation/separation steps were modeled by response surface methodology (RSM) using Box-Behnken (BBD) design. The significance of the independent variables and their interactions were tested by the analysis of variances (ANOVA) with 95% confidence limit. Under the optimized conditions, the Cr(III) and Cr(VI) anionic species were well separated with a single peak for each Cr species at retention times of 2.3 and 4.3 min, respectively. The relationship between the peak area and concentration was linear in the range of 0.025-30 for Cr(III) and 0.5-20 mg L(-1) for Cr(VI) with detection limits of 0.010 and 0.210 mg L(-1) for Cr(III) and Cr(VI), respectively. The proposed method was validated by simultaneous separation and determination of the Cr species in tap and underground water samples without impose to any pretreatment.

  7. Influence of cation substitution and activator site exchange on the photoluminescence properties of Eu3+-doped quaternary pyrochlore oxides. (United States)

    Mahesh, S K; Rao, P Prabhakar; Thomas, Mariyam; Francis, T Linda; Koshy, Peter


    Stannate-based pyrochlore-type red phosphors CaGd(1-x)SnNbO7:xEu(3+), Ca(1-y)Sr(y)Gd(1-x)SnNbO7:xEu(3+), and Ca(0.8-x)Sr0.2GdSnNbO(7+δ): xEu(3+) were prepared via conventional solid-state method. Influence of cation substitution and activator site control on the photoluminescence properties of these phosphors are elucidated using powder X-ray diffraction, Rietveld analysis, Raman spectrum analysis, and photoluminescence excitation and emission spectra. The Eu(3+) luminescence in quaternary pyrochlore lattice exemplifies as a very good structural probe for the detection of short-range disorder in the lattice, which otherwise is not detected by normal powder X-ray diffraction technique. The Eu(3+) emission due to magnetic dipole transition ((5)D0-(7)F1 MD) is modified with the increase in europium concentration in the quaternary pyrochlore red phosphors. (5)D0-(7)F1 MD transition splitting is not observable for low Eu(3+) doping because of the short-range disorder in the pyrochlore lattice. Appearance of narrow peaks in Raman spectra confirms that short-range disorder in the crystal lattice disappears with progressive europium doping. By using Sr as a network modifier ion in place of Ca we were able to increase the f-f transition intensities and europium quenching concentration. The influence of effective positive charge of the central Eu(3+) ions when it replaces a metal ion having lower oxidation state such as Ca(2+) was also investigated. The relative intensities of A1g (∼500 cm(-1)) and F2g (∼330 cm(-1)) Raman vibrational modes get inverted when Eu(3+) ions replaces Ca(2+) ions instead of Gd(3+) as trivalent europium ions can attract the electron cloud of oxygen ions strongly in comparison with divalent calcium ions. The influence of positive charge effect of Eu(3+) in Ca0.7Sr0.2GdSnNbO7+δ:0.1Eu(3+) phosphor is greatly strengthened the charge transfer band and (7)F0-(5)L6 transition intensities than that of the Ca0.8Sr0.2Gd0.9SnNbO7:0.1Eu(3+) phosphor. Our

  8. Microwave-assisted grafting polymerization modification of nylon 6 capillary-channeled polymer fibers for enhanced weak cation exchange protein separations

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Liuwei; Marcus, R. Kenneth, E-mail:


    A weak cation exchange liquid chromatography stationary phase (nylon-COOH) was prepared by grafting polyacrylic acid on to native nylon 6 capillary-channeled polymer (C-CP) fibers via a microwave-assisted radical polymerization. To the best of our knowledge, this is the first study of applying microwave-assisted grafting polymerization to affect nylon material for protein separation. The C-CP fiber surfaces were characterized by attenuated total reflection (ATR) infrared spectroscopy and scanning electron microscope (SEM). The anticipated carbonyl peak at 1722.9 cm{sup −1} was found on the nylon-COOH fibers, but was not found on the native fiber, indicating the presence of the polyacrylic acid on nylon fibers after grafting. The nylon-COOH phase showed a ∼12× increase in lysozyme dynamic binding capacity (∼12 mg mL{sup −1}) when compared to the native fiber phase (∼1 mg mL{sup −1}). The loading capacity of the nylon-COOH phase is nearly independent of the lysozyme loading concentration (0.05–1 mg mL{sup −1}) and the mobile phase linear velocity (7.3–73 mm s{sup −1}). The reproducibility of the lysozyme recovery from the nylon-COOH (RSD = 0.3%, n = 10) and the batch-to-batch variability in the functionalization (RSD = 3%, n = 5) were also investigated, revealing very high levels of consistency. Fast baseline separations of myoglobin, α-chymotrypsinogen A, cytochrome c and lysozyme were achieved using the nylon-COOH column. It was found that a 5× increase in the mobile phase linear velocity (7.3-to-36.5 mm s{sup −1}) had little effect on the separation resolution. The microwave-assisted grafting polymerization has great potential as a generalized surface modification methodology across the applications of C-CP fibers. - Highlights: • A microwave-assisted grafting method to attach acrylic acid is described for the first time for chromatographic phases. • A high-density, weak cation exchange surface is created on a nylon

  9. A contribution to the study of the extraction of mineral acids and of actinide (IV) and (VI) cations by N,N-dialkylamides; Contribution a l'etude de l'extraction d'acides mineraux et de cations actinides aux degres d'oxydation (IV) et (VI) par des N,N-dialkylamides

    Energy Technology Data Exchange (ETDEWEB)

    Condamines, N.


    N,N-dialkylamides are alternate extractants to tributylphosphate, TBP, for the actinides separation in nuclear fuel reprocessing. N,N-di (2-ethyl hexyl) butyramide and N,N-di (2 ethyl hexyl) isobutyramide are selected for their sufficient extraction and partition ability towards actinides (IV) and (VI) without coextracting fission products. Mechanisms of HNO{sub 3}, UO{sub 2}{sup 2+}, Pu{sup 4+}, Th{sup 4+} are investigated. Nitric acid extraction is due to the competitive formation of the species (HNO{sub 3})L{sub 2}, (HNO{sub 3})L, (HNO{sub 3}){sub 2}L (L: DOBA or DOiBA). An hydrogen bond is the driving force of the transfer. For low acidity media, amides are neutral extractants. Physical interactions, between free ligand and metallic complex, arise for high amide concentrations. Taking into account the non-ideality of the organic medium by a hard spheres mixture model, we estimate that such interactions are far from negligible and very specific to the amide group. Unlike TBP, when increasing acidity, amides behave as anionic extractants. DOBA and DOiBA appear to be satisfactory extractants for fuel reprocessing.


    Directory of Open Access Journals (Sweden)

    R. E. Khoma


    Full Text Available The literature data on the thermodynamics of ethanolamines onium cations dissociation have been systematized and generalized. The correlation between these cations dissociation thermodynamic functions (DH and DS and physicochemical properties (Tmp., Tbp, Pp, lgPow et al. has been revealed. There was a correlation between lipophilicity determined experimentally and calculated by QSAR. For monoethanolammonium, diethanolammonium, and their N-methyl and N-ethyl derivatives it was found dissociation thermodynamic functions to depend on bases lgPow. Acid-base dissociation of TRIS and triethanolamine onium cations does not correspond to said relationship because TRIS (primary amine, TEA (tertiary amine act differently on aqueous solutions of SO2. TEA, unlike MEA, DEA and MMEA, has a salting out effect towards sulfur dioxide because of competing hydration that promotes sulfite «onium» salts hydrolysis. TRIS promotes S(IV → S(VI sulphooxidation, in contrast to another ethanolamines. Enthalpy–enthropy compensation with isothermodynamic temperature 303 K has been recorded. The revealed correlations may be useful in developing of procedures for air sanitary cleaning from acidic gases; chemisorbents immobilized for gas and ion exchange chromatography; potentiometric methods for fluorocomplex acids determinations. The use of monoethanolamine is most promising to obtain chemisorbents because the thermodynamic functions of its onium cation acid-base dissociation are least dependent on temperature compared to other etanolammonium cations.

  11. Rapid comprehensive amino acid analysis by liquid chromatography/tandem mass spectrometry: comparison to cation exchange with post-column ninhydrin detection. (United States)

    Dietzen, Dennis J; Weindel, Annette L; Carayannopoulos, Mary O; Landt, Michael; Normansell, Ellen T; Reimschisel, Tyler E; Smith, Carl H


    Ion-exchange chromatography with ninhydrin detection remains the gold standard for detecting inborn errors of amino acid catabolism and transport. Disadvantages of such analysis include long chromatography times and interference from other ninhydrin-positive compounds. The aim of this project was to develop a more rapid and specific technique using liquid chromatography/tandem mass spectrometry (LC/MS/MS). Optimal fragmentation patterns for 32 amino acids were determined on a triple quadrupole mass spectrometer following butylation. Chromatographic characteristics of each of the amino acids were determined using C8 reversed-phase chromatography with 20% acetonitrile/0.1% formic acid as isocratic mobile phase. Quantitation using eleven deuterated internal standards was compared to cation exchange and ninhydrin detection on a Beckman 7300 system. Following methanol extraction and butylation, determination of 32 amino acids required 20 min. The dynamic range of each amino acid was generally 1-1000 micromol/L. Imprecision ranged from 7 to 23% (CV) over 6 months and recovery ranged from 88-125%. Deming regression with the Beckman 7300 yielded slopes from 0.4-1.2, intercepts from -21 to 65 micromol/L, correlation coefficients from 0.84-0.99 and Syx from 2-125 micromol/L. Isobaric amino acids were separated by chromatography (e.g. leucine, isoleucine) or by unique fragmentation (e.g., alanine, beta-alanine). LC/MS/MS is comparable to traditional LC-ninhydrin detection. Mass spectral detection shortens analysis times and reduces potential for interference in detecting inborn metabolic errors.

  12. A three-factor Doehlert matrix design in optimising the determination of octadecyltrimethylammonium bromide by cation-exchange chromatography with suppressed conductivity detection. (United States)

    Cataldi, Tommaso R I; Orlando, Donatella; Nardiello, Donatella; Rubino, Alessandra; Bianco, Giuliana; Abate, Salvatore; Ciriello, Rosanna; Guerrieri, Antonio


    A simple and effective chromatographic method with suppressed conductivity detection was developed and validated to determine dissolved samples of octadecyltrimethylammonium bromide (C18H37N+ Me3Br-, ODTAB) for purity testing. A response surface methodology generated with a Doehlert matrix design was applied to optimize the chromatographic and detection conditions in ion-exchange chromatography (IEC) with conductivity detection in the chemical suppression mode. A three-factor Doehlert design was performed to fit a second-order model and jointly optimize the peak intensity and shorten analysis time through a global desirability function. Regenerant flow rate, volume fraction of acetonitrile in the acidic eluent and its flow rate were studied at seven, five and three levels, respectively. The optimized separation and detection conditions were accomplished by using a cation-exchange column eluted at 0.5 mL min(-1) with an isocratic mobile phase composed of CH3CN and 25 mN H2SO4, 82/18 (v/v). Chemical suppression of ionic conductivity was performed by 100 mN tetrabutylammonium hydroxide (TBAOH) as a regenerant at a flow-rate of 4.0 mL min(-1). Remarkably good agreement was found between predicted and experimental values of signal intensity and chromatographic retention. With the developed method, a linear calibration curve of ODTA+ as bromide salt from 5 to 1000 ppm was obtained using hexadecyltrimethylammonium bromide as internal standard. The estimated limit of detection was 0.3 ppm (S/N=3). The effectiveness of electrochemically suppressed conductivity detection of ODTA+ was also demonstrated, thus making easier the whole detection operation and instrumental needs as well.

  13. Cation-exchange induced high power electrochemical properties of core-shell Ni(OH){sub 2} rate at CoOOH

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Weihua [College of Chemistry and Molecular Science, Wuhan University, 430072 Wuhan (China); Department of Chemistry, Zhengzhou University, 450001 Zhengzhou (China); Yang, Yifu; Shao, Huixia [College of Chemistry and Molecular Science, Wuhan University, 430072 Wuhan (China)


    New applications such as hybrid electric vehicles and power backup require rechargeable batteries to combine high energy density with high charge and discharge rate capability. In this study, the core-shell Ni(OH){sub 2} rate at CoOOH composite is constructed via a simple cation-exchange route at moderate conditions. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX), and inductively coupled plasma (ICP) are used to characterize the resulting Ni(OH){sub 2} rate at CoOOH composites. The Ni(OH){sub 2} rate at CoOOH electrode exhibits high power, higher capacity and longer life cycle when it is chosen as an positive electrode material for rechargeable alkaline MH-Ni battery. The enhanced electrochemical performance is attributed to the seamless combination of the CoOOH shell and the Ni(OH){sub 2} core, avoiding the contact resistance between them at a large current density. It is believed that our methodology provides a simple and environment friendly route to a variety of core-shell materials with different composition and novel function. (author)

  14. Analysis of amphetamine and methamphetamine in municipal wastewater influent and effluent using weak cation-exchange SPE and LC-MS/MS. (United States)

    Boles, Tammy H; Wells, Martha J M


    Amphetamine and methamphetamine are emerging contaminants-those for which no regulations currently require monitoring or public reporting of their presence in our water supply. In this research, a protocol for weak cation-exchange (WCX) SPE coupled with LC-MS/MS was developed for determination of emerging contaminants amphetamine and methamphetamine in a complex wastewater matrix. Gradient LC parameters were adjusted to yield baseline separation of methamphetamine from other contaminants. Methamphetamine-D5 was used as the internal standard (IS) to compensate for sample loss during SPE and for signal loss during MS (matrix effects). Recoveries were 102.1 ± 7.9% and 99.4 ± 4.0% for amphetamine and methamphetamine, respectively, using WCX sorbent. Notably, methamphetamine was determined to be present in wastewater influent at each sampling date tested. Amphetamine was present in wastewater influent on two of four sampling dates. Amphetamine concentrations ranged from undetectable to 86.4 ng/L in influent, but it was undetectable in wastewater effluent. Methamphetamine was detected in influent at concentrations ranging from 27.0-60.3 ng/L. Methamphetamine concentration was reduced but incompletely removed at this facility. Although absent in one post-UV effluent sample, concentrations of methamphetamine ranged from 10.8-14.8 ng/L. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Cation-exchange solid-phase and liquid-liquid extraction for the determination of khat alkaloids by reversed phase HPLC-DAD

    Directory of Open Access Journals (Sweden)

    M. Atlabachew


    Full Text Available Leaves of khat (Catha edulis are masticated to elicit their psycho-stimulating properties, resulting from the presence of the phenylpropylamino alkaloids. The determination of these alkaloids is important in pharmacological, phytochemical, forensic and law enforcement environments. In this study, the use of strong cation exchange-solid phase extraction (SCX-SPE was investigated as an alternative means of sample purification prior to the determination of cathinone, cathine and norephedrine by reversed phase (C18 high performance liquid chromatography (HPLC. Extraction parameters for SCX, including loading capacity and washing solvents, were established. An existing liquid-liquid extraction (LLE method was improved in terms of recoveries obtained, by using ethyl acetate as extractant. For pure standards of the khat alkaloids, recoveries ranged from 83 to 97%. Preconcentration, using a Genevac evaporator after the addition of acidified water to the sample, restricted analyte losses when compared to concentration under nitrogen. Although comparable recoveries were obtained when preconcentration was achieved in the presence of acidified water by rotary evaporation, this method is not suitable for large sample numbers. Best recoveries, ranging from 94 to 102%, were obtained by SCX from spiked samples. Although the extraction efficiencies of LLE were lower (87-90%, LLE yielded less complex chromatograms, indicating a purer extract.DOI:

  16. Modeling and robust pooling design of a preparative cation-exchange chromatography step for purification of monoclonal antibody monomer from aggregates. (United States)

    Borg, Niklas; Brodsky, Yan; Moscariello, John; Vunnum, Suresh; Vedantham, Ganesh; Westerberg, Karin; Nilsson, Bernt


    This study has implemented and calibrated a model that describes the separation of the monomer of monoclonal antibodies from the dimer and larger oligomers on preparative-scale using cation-exchange chromatography. A general rate model with temperature dependent diffusion was coupled to a pH- and temperature-dependent steric mass action model. The model was shown to predict the retention of the monomer, dimer, and oligomer at low loadings for different pH levels and temperatures. Additionally, the model was shown to adequately predict the elution behavior of the monomer and soluble aggregates at high loadings within the same ranges with some limitations. The model was not able to accurately describe the shape of the product break-through curves or the slight levels of co-elution of the dimer and oligomer with the monomer at higher pH. The model was used to predict how 12 process variations impact the separation. The model is used to establish an elution end collection criterion such that the step can robustly provide the target purity of monomers. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Fast analysis of quaternary ammonium pesticides in food and beverages using cation-exchange chromatography coupled with isotope-dilution high-resolution mass spectrometry. (United States)

    Nardin, Tiziana; Barnaba, Chiara; Abballe, Franco; Trenti, Gianmaria; Malacarne, Mario; Larcher, Roberto


    A fast separation based on cation-exchange liquid chromatography coupled with high-resolution mass spectrometry is proposed for simultaneous determination of chlormequat, difenzoquat, diquat, mepiquat and paraquat in several food and beverage commodities. Solid samples were extracted using a mixture of water/methanol/formic acid (69.6:30:0.4, v/v/v), while liquid samples were ten times diluted with the same solution. Separation was carried out on an experimental length-modified IonPac CS17 column (2 × 15 mm(2) ) that allowed the use of formic acid and acetonitrile as mobile phase. Detection limits for food and beverage matrices were established at 1.5 μg/L for chlormequat, difenzoquat and mepiquat, and 3 μg/L for diquat and paraquat, while for drinking water a pre-analytical sample concentration allowed detection limits of 9 and 20 ng/L, respectively. Precision, as repeatability (RSD%), ranged from 0.2 to 24%, with a median value of 6%, and trueness, as recovery, ranged from 64 to 118%, with a median value of 96%. The method developed was successfully applied to investigate the presence of herbicide residues in commercial commodities (mineral water, orange juice, beer, tea, green coffee bean, toasted coffee powder, cocoa bean, white corn flour, rice and sugar samples). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Quantitative determination of 22 primary aromatic amines by cation-exchange solid-phase extraction and liquid chromatography-mass spectrometry. (United States)

    Aznar, Margarita; Canellas, Elena; Nerín, Cristina


    Primary aromatic amines (PAAs) have been broadly studied due to their high toxicity. In this work a method for the analysis of 22 PAAs in aqueous simulants has been developed. The method is based on a solid-phase extraction step using cation-exchange cartridges and the subsequent analysis of the extracts by ultra-high-performance liquid chromatography with mass spectrometric detection. The recoveries obtained for all the amines analyzed ranged between 81 and 109%, linear range was between 0.03 and 75 microg L(-1), with the RSD values between 4.5 and 13.4% and an average value of 7.5% and limits of detection at microg L(-1) level. The method has been applied to two real samples obtained from migration experiments of polyurethane based laminates to simulant B (water with 3% (w/v) acetic acid) which represents the worst case for the migration of aromatic amines. The main amines found in both samples were methylenedianiline isomers, obtained from the corresponding residual diisocyanates used during polyurethane adhesive polymerization. The total amine concentration found was 26 and 6.3 microg of aniline equivalents per kg of food simulant.

  19. 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


    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

  20. Application of response surface methodology and artificial neural network: modeling and optimization of Cr(VI) adsorption process using Dowex 1X8 anion exchange resin. (United States)

    Harbi, Soumaya; Guesmi, Fatma; Tabassi, Dorra; Hannachi, Chiraz; Hamrouni, Bechir


    We report the adsorption efficiency of Cr(VI) on a strong anionic resin Dowex 1X8. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis of this adsorbent were investigated. Response surface methodology was applied to evaluate the main effects and interactions among initial pH, initial Cr(VI) concentration, adsorbent dose and temperature. Analysis of variance depicted that resin dose and initial pH were the most significant factors. Desirability function (DF) showed that the maximum Cr(VI) removal of 95.96% was obtained at initial pH 5, initial Cr(VI) concentration of 100 mg/L, resin dose of 2 g and temperature of 283 K. Additionally, a simulated industrial wastewater containing 14.95 mg/L of Cr(VI) was treated successfully by Dowex 1X8 at optimum conditions. Same experimental design was employed to develop the artificial neural network. Both models gave a high correlation coefficient (RRSM(2) = 0.932, RANN(2) = 0.996).

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

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


    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

  2. Ternary water in oil microemulsions made of cationic surfactants, water, and aromatic solvents. 2. Droplet sizes and interactions and exchange of material between droplets

    Energy Technology Data Exchange (ETDEWEB)

    Jada, A.; Lang, J.; Zana, R. (CNRS-ULP, Strasbourg (France)); Makhloufi, R.; Hirsch, E.; Candau, S.J. (Laboratoire de Spectrometrie et d' Imagerie Ultrasonores, Strasbourg (France))


    Ternary water in oil microemulsions made of cationic surfactants, water, and aromatic solvents have been investigated by means of time-resolved fluorescence quenching, quasi-elastic light scattering, and electrical conductivity in order to determine the surfactant aggregation number N per water droplet, the rate constant k{sub e} for the exchange of material between droplets through collisions with temporary merging, the droplet diffusion coefficient D, and the coefficient of interaction between droplets {alpha} and to study the occurrence of electrical percolation as a function of the surfactant chain length, head-group size, and water content of system (expressed as the molar concentration ratio {omega} = (water)/(surfactant)). Most measurements were performed with chlorobenzene as solvent. In one instance, chlorobenzene was substituted by benzene in order to investigate the effect of the nature of the solvent. For a given surfactant, N and k{sub e} increased with {omega} and upon substituting chlorobenzene by benzene. Also, at a given {omega}, N and k{sub e} increased when the surfactant chain length was decreased. The increases of k{sub e} were always extremely large. The droplet hydrodynamic radii from quasi-elastic light scattering were found to agree with the droplet sizes calculated with the N values from fluorescence quenching. The droplet interaction coefficient {alpha} became more negative as the surfactant chain length decreased, indicating increasingly attractive interdroplet interactions. Finally, electrical percolation was found to occur in all systems where interdroplet interactions were sufficiently attractive. The percolation threshold {omega}-values increased with surfactant chain length.

  3. Organic analysis by ion chromatography. 1. Determination of aromatic amines and aromatic diisocyanates by cation-exchange chromatography with amperometric detection. (United States)

    Zhu, Yan; Wang, Muhua; Du, Huangyong; Wang, Fang; Mou, Shifen; Haddad, Paul R


    A method has been developed for the simultaneous determination of a range of aromatic amines using cation-exchange chromatography performed on a standard ion chromatography column using d.c. amperometric detection. The analytes separated were 2,4- and 2,6-toluenediamine (2,4- and 2,6-TDA), aniline, o-toluidine, benzidine, p-chloroaniline, 4,4'-diaminodiphenyl (4,4'-DDP), m-nitroaniline and 1-naphthylamine. A Dionex CS12 column was used with gradient elution from an initial eluent of 5% CH3CN+35 mM H2SO4 to 27% CH3CN+35 mM H2SO4 (at 35 min). Detection limits in the range 2.6-22.6 microg/l were observed for all analytes except m-nitroaniline, for which the detection limit was 201 microg/l. Linear calibrations and good precision were observed and the method was applied to the determination of benzidine, p-chloroaniline and 1-naphthylamine in wastewater samples. Further, the separation was also used (after some modification of the eluent conditions) for the determination of 2,4- and 2,6-toluene diisocyanate (2,4- and 2,6-TDI) and 4,4'-methylenediphenyl diisocyanate (4,4'-MDI) after their hydrolysis to 2,4-TDA, 2,6-TDA and 4,4'-DDP. Detection limits for 2,6- and 2,4-TDI and 4,4'-MDI were 3.8, 8.2, and 11.2 microg/l, respectively. The method was applied to the determination of diisocyanates in air.

  4. Integrated strong cation-exchange hybrid monolith coupled with capillary zone electrophoresis and simultaneous dynamic pH junction for large-volume proteomic analysis by mass spectrometry. (United States)

    Zhang, Zhenbin; Sun, Liangliang; Zhu, Guijie; Yan, Xiaojing; Dovichi, Norman J


    A sulfonate-silica hybrid strong cation-exchange (SCX) monolith was synthesized at the proximal end of a capillary zone electrophoresis column and used for on-line solid-phase extraction (SPE) sample preconcentration. Sample was prepared in an acidic buffer and deposited onto the SCX-SPE monolith and eluted using a basic buffer. Electrophoresis was performed in an acidic buffer. This combination of buffers results in formation of a dynamic pH junction, which allows use of relatively large elution buffer volume while maintaining peak efficiency and resolution. All experiments were performed with a 50 µm ID capillary, a 1cm long SCX-SPE monolith, a 60cm long separation capillary, and a electrokinetically pumped nanospray interface. The volume of the capillary is 1.1 µL. By loading 21 µL of a 1×10(-7) M angiotensin II solution, an enrichment factor of 3000 compared to standard electrokinetic injection was achieved on this platform while retaining efficient electrophoretic performance (N=44,000 plates). The loading capacity of the sulfonate SCX hybrid monolith was determined to be ~15 pmol by frontal analysis with 10(-5) M angiotensin II. The system was also applied to the analysis of a 10(-4) mg/mL bovine serum albumin tryptic digest; the protein coverage was 12% and 11 peptides were identified. Finally, by loading 5.5 µL of a 10(-3) mg/mL E. coli digest, 109 proteins and 271 peptides were identified in a 20 min separation; the median separation efficiency generated by these peptides was 25,000 theoretical plates. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. LC-MS/MS analysis of pramipexole in mouse plasma and tissues: elimination of lipid matrix effects using weak cation exchange mode based solid-phase extraction. (United States)

    Guo, Weilin; Li, Gao; Yang, Yanxia; Yang, Conglian; Si, Luqin; Huang, Jiangeng


    Intranasal delivery is emerging as a promising alternative for oral or intravenous administration of central nervous system (CNS) drugs, such as pramipexole which is widely used for the treatment of Parkinson's disease. To evaluate the effectiveness of intranasal delivery of pramipexole, preclinical pharmacokinetic and tissue distribution studies following intranasal administration need to be investigated. In this paper, we developed and validated a robust and sensitive LC-MS/MS assay without matrix effect for accurate measurements of pramipexole in mouse plasma and tissue samples. Pramipexole and its stable isotope labeled internal standard (d3-pramipexole) were extracted from biological samples by protein precipitation (PPT) coupled with solid phase extraction (SPE) using weak cation exchange SPE cartridges. Matrix effects were studied using post-column infusion and post-extraction addition experiments by direct monitoring of typical phospholipids including glycerophosphocholines (GPChos) and lysoglycerophosphocholines (Lyso-GPChos). Chromatographic separation was achieved on a Welch Ultimate(®) XB-CN column using isocratic elution with a run time of 3.0 min. The assay was linear in the concentration range of 0.05-100 ng/mL and the intra- and inter-day precision and accuracy met the acceptance criteria. Compared with previous reported assays, the current sample preparation approach exhibited significant reduction of matrix effects due to the dramatically decreased levels of residual matrix components such as GPChos and Lyso-GPChos. This method has been successfully applied to pharmacokinetic and tissue distribution studies of pramipexole in mice following a single intravenous or intranasal dose of 50 μg/kg. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. 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. (United States)

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


    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. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. P retention and cation exchange as affected by nanoparticle of volcanic ash and application of phosphate solubilizing bacteria on Andisol Ciater, West Java, Indonesia (United States)

    Fitriatin, Betty Natalie; Arifin, Mahfud; Devnita, Rina; Yuniarti, Anni; Haryanto, Rachmat; Setiabudi, Mariska Amalia


    Andisols is a soil with high retention of phosphate and cannot be absorbed by plants. Some of soil bacteria have the ability to solubilize P and make it available to growing plants are known phosphate solubilizing bacteria (PSB). The research aims to study the effect of nanoparticle volcanic ash and phosphate solubilising bacteria (PSB) on P retention and cation exchangeable (CEC) in Andisol Ciater, West Java. This research was conducted from October 2016 to March 2017. The design of the analysis used was a complete randomized factorial design with two factors. The first factor was nanoparticle volcanic ash (a) consists of four dosages based on weight percentage (0%, 2.5%, 5.0% and 7.5%) and the second factor was PSB (h) consists of two dosages (without biofertilizer and with biofertilizer 1 g/Kg soil). The combination treatments replicated three times were incubated for 4 months. Soil samples were analyzed at first month and fourth month after incubation. The results showed that all dosages of nanoparticle volcanic ash and application of PSB decreased P retention by 75-77% at the first month after incubation. Nanoparticle volcanic ash dosage decreased to 7.5% the P retention reaches 90.36% in the fourth month after incubation. The nanoparticle of volcanic ash dosage 7.5% increased with CEC (24.787 and 16.555 at the first and fourth months after incubation. The application of PSB increased the CEC (28.606 in the first month after incubation.

  8. Geometry VI

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 8. Geometry VI - Space-the Final Frontier. Kapil H Paranjape. Series Article Volume 1 Issue 8 August 1996 pp 28-33. Fulltext. Click here to view fulltext PDF. Permanent link: ...

  9. VI KA’

    DEFF Research Database (Denmark)

    Sprogøe, Jonas


    Artiklen handler om hvordan man kan bruge et spil til at udvikle og måle kompetencer. Artiklen diskuterer forskellige forståelser kompetencebegrebet og diskuterer hvordan Vi Ka'-spillet bidrager til at indfange den mere aktive forståelse af kompetence, som noget du gør i en bestemt kontekst....

  10. Actinide cation-cation complexes

    Energy Technology Data Exchange (ETDEWEB)

    Stoyer, Nancy Jane [Univ. of California, Berkeley, CA (United States)


    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO2+) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO2+; therefore, cation-cation complexes indicate something unique about AnO2+ cations compared to actinide cations in general. The first cation-cation complex, NpO2+•UO22+, was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO2+ species, the cation-cation complexes of NpO2+ have been studied most extensively while the other actinides have not. The only PuO2+ cation-cation complexes that have been studied are with Fe3+ and Cr3+ and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO2+•UO22+, NpO2+•Th4+, PuO2+•UO22+, and PuO2+•Th4+ at an ionic strength of 6 M using LIPAS are 2.4 ± 0.2, 1.8 ± 0.9, 2.2 ± 1.5, and ~0.8 M-1.

  11. Cation dependencies and turnover rates of the human K⁺-dependent Na⁺-Ca²⁺ exchangers NCKX1, NCKX2, NCKX3 and NCKX4. (United States)

    Jalloul, Ali H; Szerencsei, Robert T; Schnetkamp, Paul P M


    The Solute Carrier Family 24 (SLC24) belongs to the CaCA super family of Ca(2+)/cation antiporters and codes for five different K(+)- dependent Na(+)- Ca(2+) exchangers (NCKX1-5). NCKX proteins play a critical role in Ca(2+) homeostasis in a wide variety of biological processes such as vision, olfaction, enamel formation, Melanocortin-4-receptor-dependent satiety and skin pigmentation. NCKX transcripts are widely found throughout the brain. In this study we examine the differences between NCKX1-4 in terms of cation dependencies. We measured changes to Ca(2+) influx via the reverse exchange mode while manipulating external Ca(2+) or K(+) or internal Na(+) concentrations (External Ca(2+) Dependence, External K(+) Dependence and Internal Na(+) Dependence respectively); we also looked at the effect of external Na(+)/Ca(2+) competition and 3' 4'-Dichlorobenzamil on the transport of ions in HEK 293 cell lines. A fluorescence based assay was used to determine differences in transport kinetics of the four membrane spanning exchangers using the Michaelis-Menten constant (Km). Our results show that there are no significant differences between the NCKX isoforms to explain the variation in the specific expression pattern of these exchangers. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. The removal of toxic metals from liquid effluents by ion exchange resins. Part I: Chromium(VI/Sulphate/Dowex 1x8

    Directory of Open Access Journals (Sweden)

    Alguacil, F. J.


    Full Text Available The removal of chromium (VI from sulphuric acid solutions using the Dowex 1x8 resin has been investigated. The influence of several variables such as the stirring speed, temperature, the sulphuric acid and metal concentrations in the aqueous phase and the variation of the amount of resin added has been studied. Various aqueous solutions were used for the elution of the metal. Although concentrated nitric acid elutes chromium, this can be best accomplished using hydrazine sulphate solutions which at the same time reduce the toxic Cr (VI to the less toxic trivalent chromium state. Results obtained from batch experiments were applied to a continuous system using vertical columns. Moreover, an analytical application of the system in the determination of Cr (VI presents in the leachate of an EAF dust was investigated by transfering the methodology to an on-line flow injection system.

    Se estudia la eliminación de cromo(VI presente en disoluciones de ácido sulfúrico mediante la resina Dowex 1x8. Las variables experimentales estudiadas fueron: velocidad de agitación, temperatura, las concentraciones de metal y ácido sulfúrico en el medio acuoso y la cantidad de resina añadida. Se utilizaron diversas disoluciones acuosas para eluir al metal. Aunque el ácido nítrico se puede utilizar como eluyente, la operación de elución parece ser más eficiente cuando se emplean disoluciones de sulfato de hidracina que, al mismo tiempo, reduce el cromo(VI a cromo(III. Los resultados obtenidos en los ensayos en discontinuo se han experimentado en sistemas en continuo, utilizando mini-columnas. Por último, se ha aplicado el sistema a la determinación analítica del cromo(VI presente en los lixiviados de un polvo de horno de arco eléctrico, transfiriendo la tecnología a un sistema on-line con inyección de flujo.

  13. Microwave-assisted grafting polymerization modification of nylon 6 capillary-channeled polymer fibers for enhanced weak cation exchange protein separations. (United States)

    Jiang, Liuwei; Marcus, R Kenneth


    A weak cation exchange liquid chromatography stationary phase (nylon-COOH) was prepared by grafting polyacrylic acid on to native nylon 6 capillary-channeled polymer (C-CP) fibers via a microwave-assisted radical polymerization. To the best of our knowledge, this is the first study of applying microwave-assisted grafting polymerization to affect nylon material for protein separation. The C-CP fiber surfaces were characterized by attenuated total reflection (ATR) infrared spectroscopy and scanning electron microscope (SEM). The anticipated carbonyl peak at 1722.9 cm(-1) was found on the nylon-COOH fibers, but was not found on the native fiber, indicating the presence of the polyacrylic acid on nylon fibers after grafting. The nylon-COOH phase showed a ∼12× increase in lysozyme dynamic binding capacity (∼12 mg mL(-1)) when compared to the native fiber phase (∼1 mg mL(-1)). The loading capacity of the nylon-COOH phase is nearly independent of the lysozyme loading concentration (0.05-1 mg mL(-1)) and the mobile phase linear velocity (7.3-73 mm s(-1)). The reproducibility of the lysozyme recovery from the nylon-COOH (RSD = 0.3%, n = 10) and the batch-to-batch variability in the functionalization (RSD = 3%, n = 5) were also investigated, revealing very high levels of consistency. Fast baseline separations of myoglobin, α-chymotrypsinogen A, cytochrome c and lysozyme were achieved using the nylon-COOH column. It was found that a 5× increase in the mobile phase linear velocity (7.3-to-36.5 mm s(-1)) had little effect on the separation resolution. The microwave-assisted grafting polymerization has great potential as a generalized surface modification methodology across the applications of C-CP fibers. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Redox speciation of iron, manganese, and copper in cerebrospinal fluid by strong cation exchange chromatography - sector field inductively coupled plasma mass spectrometry. (United States)

    Solovyev, Nikolay; Vinceti, Marco; Grill, Peter; Mandrioli, Jessica; Michalke, Bernhard


    A new method of simultaneous redox speciation of iron (II/III), manganese (II/III), and copper (I/II) in cerebrospinal fluid (CSF) has been designed. For the separation of redox species strong cation exchange chromatography (SCX) with isocratic elution was employed. Species were detected using inductively coupled plasma sector field mass spectrometry (ICP-sf-MS), operating at medium resolution. The following parameters were optimized: analytical column, eluent composition and pH, CSF injection volume and dilution factor. Analytical column Dionex IonPac CS5A RFIC 4*250 mm was found to retain and separate species of interest the most effectively under the isocratic elution with a buffer, containing 50 mM ammonium citrate, 7.0 mM pyridine-2,6-dicarboxylic acid at pH = 4.2 and flow rate of 0.8 L min-1. Injection volume of 50 μL with CSF sample dilution of 1/3 (v/v) with the eluent was shown to result in minimal matrix suppression. For species identification, retention time matching with standards was used. The stability of metalloproteins (ferritin, transferrin, and ceruloplasmin) under elution conditions was evaluated. For the quantification of redox species, external calibration was employed. To avoid column contamination, a blank was run after measurement and all quantification values were blank subtracted. For recovery checks, species quantification data was verified against total content of an element, measured by dynamic reaction cell ICP-MS. Recoveries (sum of quantified species vs. total element determinations) were 82.5 ± 22% (Mn), 92 ± 11% (Fe), and 88.7 ± 12% (Cu). The method was tested using 38 real CSF samples. Limits of detection (3σ) for the CSF samples were 0.5 μg L-1, 0.6 μg L-1, and 0.8 μg L-1 for Fe, Mn, and Cu species, respectively. Retention time precision was 1-7.5% (as RSD), whereas peak area RSDs were in the range 5-11%, both depending on the species. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Development of separation technology for the removal of radium-223 from targeted thorium conjugate formulations. Part II: purification of targeted thorium conjugates on cation exchange columns. (United States)

    Frenvik, Janne Olsen; Dyrstad, Knut; Kristensen, Solveig; Ryan, Olav B


    Tumor targeting pharmaceuticals will play a crucial role in future pharma pipelines. The targeted thorium conjugate (TTC) therapeutic platform could provide real benefit to patients, whereby targeting moieties like monoclonal antibodies are radiolabelled with the alpha-emitting radionuclide thorium-227 ((227)Th, t1/2 = 18.7 days). A potential problem could be the accumulation of the long-lived daughter nuclide radium-223 ((223)Ra, t1/2 = 11.4 days) in the drug product during manufacturing and distribution. Therefore, the level of (223)Ra must be standardized before administration to the patient. The focus in this study has been the removal of (223)Ra, as the other progenies will have a very limited stay in the formulation. In this study, the purification of TTCs labeled with decayed (227)Th has been explored. Columns packed with a strong cation exchange resin have been used to sequester (223)Ra. The separation of TTC from (223)Ra has been evaluated as influenced by both formulation and process parameters with a design of experiments (DOE) study; including citrate or acetate buffer, pH, buffer concentration, presence or absence of pABA + EDTA, resin amount and sodium chloride concentration. The aim was to achieve a separation with high sorption of (223)Ra and accompanying low TTC sorption. The results were analyzed by multivariate analysis. Four regression models of TTC and (223)Ra sorption from citrate and acetate buffered formulations were developed. The predictive accuracy of sorption in the four statistical models was given by standard deviations and confidence intervals. The TTC sorption in citrate and acetate buffered formulations was affected by the identical variables and the variation in TTC sorption was comparable for the two models. However, the DOE variables had a significantly stronger impact on the (223)Ra sorption in citrate buffered formulations than the (223)Ra sorption in acetate buffer. An optimal separation with a TTC sorption


    Directory of Open Access Journals (Sweden)

    Uripto Trisno Santoso


    Full Text Available Sensitization of fulvic acid (FA on photoreduction of Cr(VI to Cr(III by TiO2 photocatalyst has been studied. Parameters influencing the sensitization, i.e., pH of medium, as well as FA concentrations, TiO2 concentrations and initial Cr(VI concentrations were critically evaluated. Extraction of FA from peat soil sampled in Gambut, South Kalimantan, Indonesia, was performed using Amberlite XAD-7 resin. The FA extract then was purified by cation exchange method using Amberlite IRA-120 resin. The TiO2 produced by Merck was used as semiconducting photocatalyst and two 30-W UV lamps (Philips® model TUV were used as photon source. The results showed that presence of FA on TiO2 suspensions could sensitize the photoreduction of Cr(VI, enhancing of the amount of reduced Cr(VI more significantly than the sensitization by humic acid. The effectiveness of this sensitization increased with increasing initial concentrations of FA, TiO2, or Cr(VI until certain concentration, but no further improvement can be observed in excess FA, TiO2, or Cr(VI concentrations. On the contrary, the effectiveness of this sensitization decreased with increasing of the medium pH.   Keywords: sensitization, fulvic acid, Cr(VI, photoreduction, TiO2.

  17. Mucopolysaccharidosis VI (United States)


    Mucopolysaccharidosis VI (MPS VI) is a lysosomal storage disease with progressive multisystem involvement, associated with a deficiency of arylsulfatase B leading to the accumulation of dermatan sulfate. Birth prevalence is between 1 in 43,261 and 1 in 1,505,160 live births. The disorder shows a wide spectrum of symptoms from slowly to rapidly progressing forms. The characteristic skeletal dysplasia includes short stature, dysostosis multiplex and degenerative joint disease. Rapidly progressing forms may have onset from birth, elevated urinary glycosaminoglycans (generally >100 μg/mg creatinine), severe dysostosis multiplex, short stature, and death before the 2nd or 3rd decades. A more slowly progressing form has been described as having later onset, mildly elevated glycosaminoglycans (generally sialidosis and mucolipidosis. Before enzyme replacement therapy (ERT) with galsulfase (Naglazyme®), clinical management was limited to supportive care and hematopoietic stem cell transplantation. Galsulfase is now widely available and is a specific therapy providing improved endurance with an acceptable safety profile. Prognosis is variable depending on the age of onset, rate of disease progression, age at initiation of ERT and on the quality of the medical care provided. PMID:20385007

  18. Mucopolysaccharidosis VI

    Directory of Open Access Journals (Sweden)

    Harmatz Paul


    Full Text Available Abstract Mucopolysaccharidosis VI (MPS VI is a lysosomal storage disease with progressive multisystem involvement, associated with a deficiency of arylsulfatase B leading to the accumulation of dermatan sulfate. Birth prevalence is between 1 in 43,261 and 1 in 1,505,160 live births. The disorder shows a wide spectrum of symptoms from slowly to rapidly progressing forms. The characteristic skeletal dysplasia includes short stature, dysostosis multiplex and degenerative joint disease. Rapidly progressing forms may have onset from birth, elevated urinary glycosaminoglycans (generally >100 μg/mg creatinine, severe dysostosis multiplex, short stature, and death before the 2nd or 3rd decades. A more slowly progressing form has been described as having later onset, mildly elevated glycosaminoglycans (generally ARSB gene, located in chromosome 5 (5q13-5q14. Over 130 ARSB mutations have been reported, causing absent or reduced arylsulfatase B (N-acetylgalactosamine 4-sulfatase activity and interrupted dermatan sulfate and chondroitin sulfate degradation. Diagnosis generally requires evidence of clinical phenotype, arylsulfatase B enzyme activity ®, clinical management was limited to supportive care and hematopoietic stem cell transplantation. Galsulfase is now widely available and is a specific therapy providing improved endurance with an acceptable safety profile. Prognosis is variable depending on the age of onset, rate of disease progression, age at initiation of ERT and on the quality of the medical care provided.

  19. 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.


    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.

  20. 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


    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

  1. Development of separation technology for the removal of radium-223 from targeted thorium conjugate formulations. Part I: purification of decayed thorium-227 on cation exchange columns. (United States)

    Frenvik, Janne Olsen; Dyrstad, Knut; Kristensen, Solveig; Ryan, Olav B


    Targeted thorium conjugates (TTCs) are being explored as a potential future platform for specific tumor targeting pharmaceuticals. In TTCs, the alpha emitting radionuclide thorium-227 ((227)Th) with a half-life of 18.697 d is labeled to targeting moieties, such as monoclonal antibodies (mAbs). The amount of daughter nuclide radium-223 ((223)Ra, t1/2 = 11.435 d) will increase during manufacture and distribution, and so a technology for purification is required to assure an acceptable level of (223)Ra is administrated to the patient. Since (223)Ra is the only progeny of (227)Th with a long half-life (days), the progenies of (223)Ra will have a very limited stay in the formulation once (223)Ra is removed. The focus in this study has, therefore, been on the removal of (223)Ra. In this study, the sorption and separation of (223)Ra (radium(II)) and (227)Th (thorium(IV)) on cation exchange columns has been evaluated as a purification method of decayed (227)Th (i.e. prior to radiolabelling of a mAb and formation of TTC). The goal is to minimize the sorption of (227)Th and maximize the sorption of (223)Ra. Statistical experimental design with formulation and process parameters, including buffered formulations comprising citrate and acetate, at various concentrations and pH, presence of free radical scavenger and chelator, and resin amount have been evaluated for impact on the purification process. The studies have been interpreted by the aid of multivariate data analysis. The correlations between design of experimental variables and sorption are summarized by regression models. The predictive accuracy of radionuclide sorption was given by standard deviation and 95% confidence intervals originating from statistical cross validation. Experimental results and statistical models for citrate-buffered formulations verified reproducible and acceptable sorption levels of (223)Ra and (227)Th under selected conditions. For acetate-buffered formulations, prediction of (227)Th

  2. A new type of polyhedron-based metal-organic frameworks with interpenetrating cationic and anionic nets demonstrating ion exchange, adsorption and luminescent properties. (United States)

    Zhang, Zheng-Jie; Shi, Wei; Niu, Zheng; Li, Huan-Huan; Zhao, Bin; Cheng, Peng; Liao, Dai-Zheng; Yan, Shi-Ping


    An interesting new MOF, built with interpenetrating cationic (MOF-A(+)) and anionic (MOF-B(-)) nets that do not require counter ions to balance charge, together with an architectural strategy focused on the use of MOPs as nodes and MOCs as spacers for the generation of 3D frameworks, is reported. This journal is © The Royal Society of Chemistry 2011

  3. Simultaneous determination of N-oxides and free bases of pyrrolizidine alkaloids by cation-exchange solid-phase extraction and ion-pair high-performance liquid chromatography. (United States)

    Mroczek, Tomasz; Glowniak, Kazimierz; Wlaszczyk, Anna


    Cation-exchange solid-phase extraction using LiChrolut SCX (Merck, Darmstadt) cartridges filled with polymeric strong cation-exchanger enabled efficient isolation of both N-oxides and free bases of pyrrolizidine alkaloids (PAs). The recoveries were about 80% for retrorsine-N-oxide, 90% for retrorsine and 100% for senkirkine and were assessed both by TLC-densitometry and ion-pair high-performance liquid chromatography (HPIPC) on Hypersil BDS C8 stationary phase and hexane-l-sulfonic acid as ion-pairing agent. The applied HPIPC gradient procedure was suitable for separation of PAs with various types of structures (N-oxides, free bases, otonecine-PAs). The method limits of detection and quantitation, respectively, ranged from 0.06 ng/microl (senecionine) and 0.2 ng/microl (senkirkine) to 0.1 and 0.35 ng/microl for retrorsine-N-oxide. For each component calibrated by linear regression method, correlation coefficients were higher than 0.9995 (six-point calibration from 4 to 100 microg/ml). The elaborated procedure was used in searching for PAs in plant derived samples from Symphytum sp. (comfrey), Petasites hybridus and Petasites albus (butterbur), Tussilago farfara (coltsfoot), Emilia coccinea (tassel flower) and Doronicum columnae (leopard's bane). For the last three samples macrocyclic PAs (senecionine, senecionine-N-oxide. senkirkine) have been detected for the first time. Details of precision of the analyses are also included.

  4. Modeling uranium(VI) adsorption onto montmorillonite under varying carbonate concentrations: A surface complexation model accounting for the spillover effect on surface potential (United States)

    Tournassat, C.; Tinnacher, R. M.; Grangeon, S.; Davis, J. A.


    The prediction of U(VI) adsorption onto montmorillonite clay is confounded by the complexities of: (1) the montmorillonite structure in terms of adsorption sites on basal and edge surfaces, and the complex interactions between the electrical double layers at these surfaces, and (2) U(VI) solution speciation, which can include cationic, anionic and neutral species. Previous U(VI)-montmorillonite adsorption and modeling studies have typically expanded classical surface complexation modeling approaches, initially developed for simple oxides, to include both cation exchange and surface complexation reactions. However, previous models have not taken into account the unique characteristics of electrostatic surface potentials that occur at montmorillonite edge sites, where the electrostatic surface potential of basal plane cation exchange sites influences the surface potential of neighboring edge sites ('spillover' effect). A series of U(VI) - Na-montmorillonite batch adsorption experiments was conducted as a function of pH, with variable U(VI), Ca, and dissolved carbonate concentrations. Based on the experimental data, a new type of surface complexation model (SCM) was developed for montmorillonite, that specifically accounts for the spillover effect using the edge surface speciation model by Tournassat et al. (2016a). The SCM allows for a prediction of U(VI) adsorption under varying chemical conditions with a minimum number of fitting parameters, not only for our own experimental results, but also for a number of published data sets. The model agreed well with many of these datasets without introducing a second site type or including the formation of ternary U(VI)-carbonato surface complexes. The model predictions were greatly impacted by utilizing analytical measurements of dissolved inorganic carbon (DIC) concentrations in individual sample solutions rather than assuming solution equilibration with a specific partial pressure of CO2, even when the gas phase was

  5. Anion exchange membranes composed of a poly(2,6-dimethyl-1,4-phenylene oxide) random copolymer functionalized with a bulky phosphonium cation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ye; Zhang, Bingzi; Kinsinger, Corey L.; Yang, Yuan; Seifert, Soenke; Yan, Yushan; Mark Maupin, C.; Liberatore, Matthew W.; Herring, Andrew M.


    A random copolymer, tris(2,4,6-trimethoxyphenyl) phosphonium functionalized poly(2,6-dimethyl-1,4-phenylene oxide) (PPO-TPQP) was cast from three different solvents: dimethyl sulfoxide (DMSO), ethyl lactate, or a 41:59 vol% mixture of DMSO and ethyl lactate. Solvents were selected via analysis of the Hansen solubility parameters to vary the phase separation of the polymer in the films. An optimized mixture of DMSO and ethyl lactate chosen for film fabrication and this film was contrasted with films cast from the neat constituent solvents. Atomic force microscopy identified domains from nanometer to tens of nanometer sizes, while the light microscopy showed features on the order of micron. SAXS revealed a cation scattering peak with a d-spacing from 7 to 15 A. Trends in conductivity and water diffusion for the membranes vary depending on the solvent from which they are cast. The mixed solvent cast membrane shows a linear Arrhenius behavior indicating fully dissociated cationic/anionic groups, and has the highest bromide conductivity of 3 mS/cm at 95% RH, 90 degrees C. The ethyl lactate cast membrane shows a linear Arrhenius relation in conductivity, but a Vogel-Tamman-Fulcher behavior in its water self-diffusion. While water increases bromide dissociation, water and bromide transport in these films seems to be decoupled. This is particularly true for the film cast from ethyl lactate.

  6. Exchange of lyotropic series cations by micaceous vermiculite and its weathering products determined by electron microscopy and radiochemical analysis. Final technical report, June 1, 1965-October 31, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, M L


    Micaceous vermiculite was found to be ubiquitous in soils, sediments, and aerosol mineral dusts and to adsorb fission product ions, particularly /sup 137/Cs/sup +/ and /sup 90/Sr/sup 2 +/. Crystallographic wedge zones (imaged by ultramicrotomy and electron microscopy) in micaceous vermiculite effected tight fixation of Cs/sup +/. Lowering of mica layer charge occurred in local areas, electronoscopically imaged by use of blister-swelling cations. Nuclear fission particle tracks of U enhanced translayer diffusion of elements, measured mica layer charge and age. Iron-aluminum hydrous oxide coatings adsorbed divalent cations of the alkaline earth, transition, and heavy metal elements from trace concentrations in the presence of 1 M NaNO/sub 3/. Global deposition of dust by rainfall accounted for the wide distribution of Cs-fixing micaceous vermiculite in soils. Origin of the dust was traced through a method developed for isolation of fine quartz silt (1 to 10 diameter). Mass spectrometry of its /sup 18/O//sup 16/O isotopic ratios showed distinctly higher (delta/sup 18/O = 17 to 22%/sub 0/) and lower (delta/sup 18/O = 9 to 15%/sub 0/) ranges in the Northern and Southern Hemispheres, respectively. This difference was traced to the relative proportions of quartz from low-temperature authigenic (chert) vs igneous-metamorphic origin in the respective latitudes, hinging on trans-equatorial continental drift.

  7. An unusual copper(I) halide-based metal-organic framework with a cationic framework exhibiting the release/adsorption of iodine, ion-exchange and luminescent properties. (United States)

    Xin, Bingjing; Zeng, Guang; Gao, Lu; Li, Yun; Xing, Shanghua; Hua, Jia; Li, Guanghua; Shi, Zhan; Feng, Shouhua


    A copper(I) halide-based compound with a formula of [Cu4I3(DABCO)2]I3 (DABCO = N,N'-dimethyl-1,4-diazabicyclo[2.2.2]octane) has been prepared by solvothermal reactions. This compound has been characterized by single-crystal X-ray diffraction, elemental analysis, IR, TG, XPS and powder X-ray diffractions. Structure analyses reveal that this compound is constructed by unprecedented cationic cluster [Cu8I6](2+) and organic ligand DABCO and the channels of this compound are occupied by I2 and I(-). The guest I2 and I(-) can move freely in and out of the host-framework. UV/vis spectra confirm that the I2 molecules in the channels can release into some organic solvents and IR spectra confirm the I(-) was exchanged by SCN(-). In addition, the luminescent properties of this compound in the solid state have also been investigated.

  8. An approach to speed up the isolation of hydrophilic metabolites from natural sources at semipreparative level by using a hydrophilic-lipophilic balance/mixed-mode strong cation exchange-high-performance liquid chromatography/mass spectrometry system. (United States)

    Espada, Alfonso; Anta, Cristina; Bragado, Aroa; Rodríguez, Jaime; Jiménez, Carlos


    An approach to speed up the isolation of hydrophilic metabolites in complex natural matrixes by using a HLB/MCX-HPLC/MS system based on the retention properties of hydrophilic-lipophilic and cation exchange polymeric cartridges was developed. This methodology was successfully applied to the re-isolation of small water soluble compounds with completely different structures from two different natural extracts such as a dipeptide (vanchrobactin) from a bacterium culture broth and a pyrrolidine bearing a carboxylic acid moiety (clionapyrrolidine A) from a sponge. This method improved not only the efficiency of the isolation methodology but also the isolation time in relation to the existing methods. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. New anion-exchange polymers for improved separations

    Energy Technology Data Exchange (ETDEWEB)

    Jarvinen, G.D.; Barr, M.E.; Marsh, S.F.


    Objective is to improve the understanding of how the structure of a new class of anion-exchange polymers controls the binding of anionic actinide complexes from solution. This is needed to develop practical separation systems that will reduce the cost of actinide processing operations within the DOE complex. In addition anion exchange is widely used in industry. Several new series of bifunctional anion- exchange polymers have been designed, synthesized, and tested for removing Pu(IV), Am(III), and U(VI) from nitric acid. The polymers contain a pyridinium site derived from the host poly(4-vinylpyridine) and a second cationic site attached through a chain of 2 to 6 methylene groups. The new polymers removed Pu four to ten times more efficiently than the best commercial materials.

  10. Fate and transport of uranium (VI) in weathered saprolite. (United States)

    Kim, Young-Jin; Brooks, Scott C; Zhang, Fan; Parker, Jack C; Moon, Ji-Won; Roh, Yul


    Batch and column experiments were conducted to investigate sorption and transport of uranium (U) in the presence of saprolite derived from interbedded shale, limestone, and sandstone sequences. Sorption kinetics were measured at two initial concentrations (C0; 1, 10 μM) and three soil:solution ratios (Rs/w; 0.005, 0.25, 2 kg/L) at pH 4.5 (pH of the saprolite). The rate of U loss from solution (μmole/L/h) increased with increasing Rs/w. Uranium sorption exhibited a fast phase with 80% sorption in the first eight hours for all C0 and Rs/w values and a slow phase during which the reaction slowly approached (pseudo)equilibrium over the next seven days. The pH-dependency of U sorption was apparent in pH sorption edges. U(VI) sorption increased over the pH range 4-6, then decreased sharply at pH > 7.5. U(VI) sorption edges were well described by a surface complexation model using calibrated parameters and the reaction network proposed by Waite et al. (1994). Sorption isotherms measured using the same Rs/w and pH values showed a solids concentration effect where U(VI) sorption capacity and affinity decreased with increasing solids concentration. This effect may have been due to either particle aggregation or competition between U(VI) and exchangeable cations for sorption sites. The surface complexation model with calibrated parameters was able to predict the general sorption behavior relatively well, but failed to reproduce solid concentration effects, implying the importance of appropriate design if batch experiments are to be utilized for dynamic systems. Transport of U(VI) through the packed column was significantly retarded. Transport simulations were conducted using the reactive transport model HydroGeoChem (HGC) v5.0 that incorporated the surface complexation reaction network used to model the batch data. Model parameters reported by Waite et al. (1994) provided a better prediction of U transport than optimized parameters derived from our sorption edges. The

  11. Recovery of Cr as Cr(III) from Cr(VI)-contaminated kaolinite clay by electrokinetics coupled with a permeable reactive barrier. (United States)

    Suzuki, Tasuma; Kawai, Katsunori; Moribe, Mai; Niinae, Masakazu


    Zero-valent iron (Fe(0)) and magnetite (Fe3O4) were investigated as potential reductants in an electrokinetic/permeable reactive barrier hybrid system (EK/PRB) for the recovery of Cr as Cr(III) from Cr(VI)-contaminated kaolinite. For the EK/Fe(0) PRB, regardless of the pH in the anode well, the system facilitated the reduction of Cr(VI) into Cr(III), but the recovery of the Cr(III) in the PRB was low. Conversely, the reduction of Cr(VI) occurred only in the PRB for the EK/Fe3O4 PRB. However, when the anode pH was not controlled and the soil pH values correspondingly decreased gradually from the anode side, a greater fraction of Cr(VI) sorbed onto the kaolinite; as a result, a lower amount of Cr(VI) migrated to the Fe3O4 PRB. In addition, it was found that the majority of Cr(VI) migrating to the Fe3O4 PRB retained its oxidation state without being converted into Cr(III). These two adverse effects were mitigated by maintaining the soil pH values at 6.8, but at the same time, 18% of Cr(VI) penetrated through the Fe3O4 PRB. The penetration of Cr(VI) through the Fe3O4 PRB was successfully prevented by increasing the reaction time through the introduction of a cation exchange membrane between the Fe3O4 PRB and the anode well. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Anion exchange membrane (United States)

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus


    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.


    Directory of Open Access Journals (Sweden)



    Full Text Available Cloud point extraction (CPE was used to extract uranium (VI from an aqueous solution in acetate media. The methodology used is based on the formation of uranyl-ionic liquid (I complexes and uranyl-D2EHPA soluble in a micellar phase of non-ionic surfactant (Triton X-100. The uranium (VI complexes are then extracted into the surfactant-rich phase at ambient temperature. The ionic liquid (IL used as a chelating agent was synthesized and characterized in this study. It is composed of N-butyl N’-triethoxy methyl imidazolium cation and diethylhexylphosphate (D2EHPA-H as anion. The effect of the IL on the extraction efficiency was studied in presence and in absence of IL’s cation in acetate medium.

  14. Cranial mononeuropathy VI (United States)

    ... Abducens palsy; Lateral rectus palsy; VIth nerve palsy; Cranial nerve VI palsy; Sixth nerve palsy; Neuropathy - sixth nerve ... Cranial mononeuropathy VI is damage to the sixth cranial nerve. This nerve is also called the abducens nerve. ...

  15. Measurement of yield of residues produced in {sup 12}C+{sup nat}Y reaction and subsequent separation of {sup 97}Ru from Y target using cation exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, Moumita [Indian Institute of Technology Roorkee, Uttarakhand (India). Dept. of Physics; Lahiri, Susanta [Saha Institute of Nuclear Physics, Kolkata (India). Chemical Sciences Div.


    This paper reports the yield of no-carrier-added (NCA) radionuclides produced in {sup 12}C{sup 6+} induced reaction on natural yttrium target at 10 different incident energies in the range of 40 to 75 MeV by the stacked-foil technique, followed by off-line γ-ray spectroscopy. It also reports the radiochemical separation of NCA {sup 97}Ru from the bulk yttrium target. {sup 97}Ru was produced in the yttrium matrix through {sup 89}Y({sup 12}C,4n){sup 97,97m}Rh(EC){sup 97}Ru and {sup 89}Y({sup 12}C,p3n){sup 97}Ru reactions along with the radioisotopes {sup 98}Rh, {sup 97}Rh, {sup 97m}Rh, {sup 93}Tc, {sup 94}Tc, {sup 95}Tc and {sup 93m}Mo. Irradiated target was allowed to cool for the complete decay of short-lived residues and {sup 97}Ru was then separated from the bulk yttrium using the cation exchanger DOWEX-50WX4 in an ion exchange column as well as via solid-liquid extraction (SLX). A total of ∝ 88% NCA {sup 97}Ru was separated in column chromatography without any contamination of bulk, whereas quantitative separation of NCA Ru was achieved in SLX.

  16. Hybrid materials: Magnetite-Polyethylenimine-Montmorillonite, as magnetic adsorbents for Cr(VI) water treatment. (United States)

    Larraza, Iñigo; López-Gónzalez, Mar; Corrales, Teresa; Marcelo, Gema


    Hybrid materials formed by the combination of a sodium rich Montmorillonite (MMT), with magnetite nanoparticles (40 nm, Fe(3)O(4) NPs) coated with Polyethylenimine polymer (PEI 800 g/mol or PEI 25000 g/mol) were prepared. The intercalation of the magnetite nanoparticles coated with PEI among MMT platelets was achieved by cationic exchange. The resulting materials presented a high degree of exfoliation of the MMT sheets and a good dispersion of Fe(3)O(4) NPs on both the surface and among the layers of MMT. The presence of amine groups in the PEI structure not only aids the exfoliation of the MMT layers, but also gives to the hybrid material the necessary functionality to interact with heavy metals. These hybrid materials were used as magnetic sorbent for the removal of hexavalent chromium from water. The effect that pH, Cr(VI) concentration, and adsorbent material composition have on the Cr(VI) removal efficiency was studied. A complete characterization of the materials was performed. The hybrid materials showed a slight dependence of the removal efficiency with the pH in a wide range (1-9). A maximum amount of adsorption capacity of 8.8 mg/g was determined by the Langmuir isotherm. Results show that these hybrid materials can be considered as potential magnetic adsorbent for the Cr(VI) removal from water in a wide range of pH. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Cation (K{sup +}, Mg{sup 2+}, Ca{sup 2+}) exchange in Pb{sup 2+} accumulation by Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Jung Ho [Dept. of Industrial Chemistry, Ulsan College, Ulsan (Korea); Yun, Jong Won [Dept. of Biotechnology, Taegu University, Kyungbuk (Korea); Kim, Dong Seog [Dept. of Environmental Science, Catholic University of Taegu-Hyosung, Kyungbuk 712-702 (Korea)


    The relationship between Pb{sup 2+} accumulation and cation (K{sup +}, Mg{sup 2+}, Ca{sup 2+}) release in Saccharomyces cerevisiae was extensively investigated. As Pb{sup 2+} accumulation proceeded, the release of cellular metal ions such as K{sup +}, Mg{sup 2+} and Ca{sup 2+} was concomitantly released within 24 h, thereafter Pb{sup 2+} penetrated into the inner cellular parts and consequently plasmolysis of the cell was observed by TEM analysis. Pb{sup 2+} accumulation process in S. cerevisiae after 24 h was metabolism-independent because of the absence of cell viability. As the cell storage time was prolonged, the released amount of K{sup +} was markedly increased, while the amount of accumulated Pb{sup 2+} was nearly constant regardless of cell storage time and the time required to reach an equilibrium state was shortened. The autoclaved cells had less Pb{sup 2+} accumulation capacity than the untreated cells, and the amounts of released K{sup +} and Mg{sup 2+} were very low due to the denaturation of cell surface and cell membrane. (orig.)


    Directory of Open Access Journals (Sweden)



    Full Text Available This paper experimentally investigates the performance and capacity of Purolite C100E commercial resin recommended for water softening applications in the food industry. The practical ion exchange capacity and the softening process efficiency are studied in batch mode as a function of the sorption specific process factors. Optimum operation conditions were determined as initial pH 7.1, resin dose 8 g dry resin•L-1, temperature 25 oC, contact time of 360 min, and in those conditions the retention capacity for the Ca2+ ions is 17.18 mg•g-1 that corresponds to a removal efficiency equal to 85.7%.

  19. Cation-Exchange Porosity Tuning in a Dynamic 4d-4f-3d Framework for Ni(II) Ion-Selective Luminescent Probe. (United States)

    Wang, Ying; Wang, Xiu-Guang; Yuan, Bin; Shao, Cheng-Yuan; Chen, Yuan-Yuan; Zhou, Bing-Bing; Li, Ming-Shu; An, Xiao-Mai; Cheng, Peng; Zhao, Xiao-Jun


    A heterometallic complex {[Yb2(L)6Cd2][Cd(H2O)6]·6H2O}n (Yb-Cd) (H2L = oxidiacetic acid) was synthesized under hydrothermal conditions. In Yb-Cd, each L chelates to one Yb(3+) center and bonds to two Cd(2+) ions in an anti-anti configuration. Yb and Cd atoms are arrayed alternatively and connected by O-C-O bridges to form a cubic octahedral cage as the secondary building unit. Consequently, topological NaCl nets with high symmetry in the cubic space group Fd-3c have been constructed. The [Cd(H2O)6](2+) moieties lying in the porosity of anionic metal-organic framework (MOF) act as the thermodynamically stable species, required to balance the two negative charges of [Yb2(L)6Cd2](2-) in Yb-Cd. Interestingly, when Yb-Cd was employed as a precursor and emerged in the aqueous solution of Mn(ClO4)2·6H2O or Zn(ClO4)2·6H2O, a reversible single-crystal-to-single-crystal transformation process driven by [Cd(H2O)6](2+) cations has been exhibited to generate the heterotrimetallic coordination polymer {[Yb2(L)6Cd2][Mn(H2O)6]·6H2O}n (Yb-Cd-Mn) or {[Yb2(L)6Cd2][Zn(H2O)6]·6H2O}n (Yb-Cd-Zn). To the best of out knowledge, Yb-Cd-Mn and Yb-Cd-Zn are the first examples representing 4d-4f-3d polymers based on multicarboxylic acid. Luminescent studies reveal that Yb-Cd-Zn may serve as a good candidate of Ni(2+) a luminescent probe. To our knowledge, Yb-Cd-Zn represent the fist example of the 4d-4f-3d framework to exhibit luminescent selectivity for Ni(2+).

  20. 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.


    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

  1. Optimizing the application of magnetic nanoparticles in Cr(VI) removal (United States)

    Simeonidis, Konstantinos; Kaprara, Efthymia; Mitrakas, Manassis; Tziomaki, Magdalini; Angelakeris, Mavroidis; Vourlias, Georgios; Andritsos, Nikolaos


    The presence of heavy metals in aqueous systems is an intense health and environmental problem as implied by their harmful effects on human and other life forms. Among them, chromium is considered as an acutely hazardous compound contaminating the surface water from industrial wastes or entering the groundwater, the major source of drinking water, by leaching of chromite rocks. Chromium occurs in two stable oxidation states, Cr(III) and Cr(VI), with the hexavalent form being much more soluble and mobile in water having the ability to enter easily into living tissues or cells and thus become more toxic. Despite the established risks from Cr(VI)-containing water consumption and the increasing number of incidents, the E.U. tolerance limit for total chromium in potable water still stands at 50 μg/L. However, in the last years a worldwide debate concerning the establishment of a separate and very strict limit for the hexavalent form takes place. In practice, Cr(VI) is usually removed from water by various methods such as chemical coagulation/filtration, ion exchange, reverse osmosis and adsorption. Adsorption is considered as the simplest method which may become very effective if the process is facilitated by the incorporation of a Cr(VI) to Cr(III) reduction stage. This work studies the potential of using magnetic nanoparticles as adsorbing agents for Cr(VI) removal at the concentration levels met in contaminated drinking water. A variety of nanoparticles consisting of ferrites MFe2O4 (M=Fe, Co, Ni, Cu, Mn, Mg, Zn) were prepared by precipitating the corresponding bivalent or trivalent sulfate salts under controlled acidity and temperature. Electron microscopy and X-ray diffraction techniques were used to verify their crystal structure and determine the morphological characteristics. The mean particle size of the samples was found in the range 10-50 nm. Batch Cr(VI) removal tests were performed in aqueous nanoparticles dispersions showing the efficiency of ferrite

  2.  Pressure-induced Fe↔Cu cationic valence exchange and its structural consequences: High-pressure studies of delafossite CuFeO2 (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.


    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.

  3. Cation exchange-based facile aqueous synthesis of small, stable, and nontoxic near-infrared Ag₂Te/ZnS core/shell quantum dots emitting in the second biological window. (United States)

    Chen, Chi; He, Xuewen; Gao, Li; Ma, Nan


    Facile aqueous synthesis of near-infrared Ag(2)Te quantum dots (QDs) and Ag(2)Te/ZnS core/shell QDs emitting in the second biological window is reported. The QD synthesis is based on a straightforward cation exchange process between CdTe QDs and Ag(+) ions conducted in aqueous solution. The prepared Ag(2)Te QDs possess near-infrared emission ranging from 900 to 1300 nm and a quantum yield up to 2.1%. A ZnS shell was grown on the Ag(2)Te QD to further enhance the photoluminescence intensity with a quantum yield of 5.6%. These Ag(2)Te/ZnS core/shell QDs possess robust colloidal stability and photostability with minimum photoluminescence fluctuation upon incubation for 72 h in biological buffer or continuous laser excitation for 120 min. Also, These QDs possess small hydrodynamic size (∼7.6 nm) and are non-cytotoxic to human cells, which is ideal for optical bioimaging in the second biological window.

  4. 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. (United States)

    Zhao, Miao; Wu, Xiao-Jie; Fan, Ya-Xin; Guo, Bei-Ning; Zhang, Jing


    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, %) colistin, which offers a highly efficient tool for the analysis of a large number of clinical samples as well as routine therapeutic drug monitoring. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Fast speciation of mercury in seawater by short-column high-performance liquid chromatography hyphenated to inductively coupled plasma spectrometry after on-line cation exchange column preconcentration. (United States)

    Jia, Xiao-Yu; Gong, Di-Rong; Han, Yi; Wei, Chao; Duan, Tai-Cheng; Chen, Hang-Ting


    A simple and fast method for trace speciation analysis of mercury (Hg(2+)), methylmercury (MeHg(+)) and ethylmercury (EtHg(+)) in seawater has been developed by short-column high-performance liquid chromatography hyphenated to inductively coupled plasma spectrometry (HPLC-ICP-MS) after on-line cation-exchange column (CEC) preconcentration. The analytes were firstly adsorbed on the CEC without any extraneous reagent, and then were eluted rapidly (within seconds) and completely with a very low concentration of l-cysteine solution, which provides the conveniency for the on-line coupling of the preconcentration method and detection technique. To our best knowledge, it is for the first time to employ the CEC preconcentration technique to trap all of the three mercury species simultaneously at their positive charged status for the purpose of speciation analysis. Under the optimized conditions, a very high preconcentration factor up to 1250 has been obtained with 30mL sample solution, which leads to the very low detection limits of 0.042ngL(-1) for Hg(2+), 0.016ngL(-1) for MeHg(+) and 0.008ngL(-1) for EtHg(+) (as Hg), respectively. With the established method, three seawater samples were also analyzed, and all the three mercury species have been found in each sample, albeit at a very low concentration. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

  6. Optimization of elution salt concentration in stepwise elution of protein chromatography using linear gradient elution data. Reducing residual protein A by cation-exchange chromatography in monoclonal antibody purification. (United States)

    Ishihara, Takashi; Kadoya, Toshihiko; Endo, Naomi; Yamamoto, Shuichi


    Our simple method for optimization of the elution salt concentration in stepwise elution was applied to the actual protein separation system, which involves several difficulties such as detection of the target. As a model separation system, reducing residual protein A by cation-exchange chromatography in human monoclonal antibody (hMab) purification was chosen. We carried out linear gradient elution experiments and obtained the data for the peak salt concentration of hMab and residual protein A, respectively. An enzyme-linked immunosorbent assay was applied to the measurement of the residual protein A. From these data, we calculated the distribution coefficient of the hMab and the residual protein A as a function of salt concentration. The optimal salt concentration of stepwise elution to reduce the residual protein A from the hMab was determined based on the relationship between the distribution coefficient and the salt concentration. Using the optimized condition, we successfully performed the separation, resulting in high recovery of hMab and the elimination of residual protein A.

  7. The use of cation exchange matrix separation coupled with ICP-MS to directly determine platinum group element (PGE) and other trace element emissions from passenger cars equipped with diesel particulate filters (DPF)

    Energy Technology Data Exchange (ETDEWEB)

    Cairns, Warren R.L.; Cozzi, Giulio [Institute for the Dynamics of Environmental Processes-CNR, Venice (Italy); De Boni, Antonella; Gabrieli, Jacopo [University of Venice, Department of Environmental Science, Venice (Italy); Asti, Massimo; Merlone Borla, Edoardo; Parussa, Flavio [Centro Ricerche Fiat, Orbassano (Italy); Moretto, Ezio [FIAT Powertrain Technologies S.p.A, Turin (Italy); Cescon, Paolo; Barbante, Carlo [University of Venice, Department of Environmental Science, Venice (Italy); Institute for the Dynamics of Environmental Processes-CNR, Venice (Italy); Boutron, Claude [Laboratoire de Glaciologie et Geophysique de l' Environnement, UMR CNRS 5183, B.P. 96, Saint Martin d' Heres Cedex (France)


    Inductively coupled plasma-mass spectrometry coupled with cation exchange matrix separation has been optimised for the direct determination of platinum group element (PGE) and trace element emissions from a diesel engine car. After matrix separation method detection limits of 1.6 ng g{sup -1} for Pd, 0.4 ng g{sup -1} for Rh and 4.3 ng g{sup -1} for Pt were achieved, the method was validated against the certified reference material BCR 723, urban road dust. The test vehicle was fitted with new and aged catalytic converters with and without diesel particulate filters (DPF). Samples were collected after three consecutive New European Driving Cycle (NEDC) of the particulate and ''soluble'' phases using a home-made sampler optimised for trace element analysis. Emission factors for the PGEs ranged from 0.021 ng km{sup -1} for Rh to 70.5 ng km{sup -1} for Pt; when a DPF was fitted, the emission factors for the PGEs actually used in the catalysts dropped by up to 97% (for Pt). Trace element emission factors were found to drop by a maximum of 92% for Ni to a minimum of 18% for Y when a DPF was fitted; a new DPF was also found to cause a reduction of up to 86% in the emission of particulate matter. (orig.)

  8. The use of cation exchange matrix separation coupled with ICP-MS to directly determine platinum group element (PGE) and other trace element emissions from passenger cars equipped with diesel particulate filters (DPF). (United States)

    Cairns, Warren R L; De Boni, Antonella; Cozzi, Giulio; Asti, Massimo; Borla, Edoardo Merlone; Parussa, Flavio; Moretto, Ezio; Cescon, Paolo; Boutron, Claude; Gabrieli, Jacopo; Barbante, Carlo


    Inductively coupled plasma-mass spectrometry coupled with cation exchange matrix separation has been optimised for the direct determination of platinum group element (PGE) and trace element emissions from a diesel engine car. After matrix separation method detection limits of 1.6 ng g(-1) for Pd, 0.4 ng g(-1) for Rh and 4.3 ng g(-1) for Pt were achieved, the method was validated against the certified reference material BCR 723, urban road dust. The test vehicle was fitted with new and aged catalytic converters with and without diesel particulate filters (DPF). Samples were collected after three consecutive New European Driving Cycle (NEDC) of the particulate and "soluble" phases using a home-made sampler optimised for trace element analysis. Emission factors for the PGEs ranged from 0.021 ng km(-1) for Rh to 70.5 ng km(-1) for Pt; when a DPF was fitted, the emission factors for the PGEs actually used in the catalysts dropped by up to 97% (for Pt). Trace element emission factors were found to drop by a maximum of 92% for Ni to a minimum of 18% for Y when a DPF was fitted; a new DPF was also found to cause a reduction of up to 86% in the emission of particulate matter.

  9. Bandgap and Structure Engineering via Cation Exchange: From Binary Ag2S to Ternary AgInS2, Quaternary AgZnInS alloy and AgZnInS/ZnS Core/Shell Fluorescent Nanocrystals for Bioimaging. (United States)

    Song, Jiangluqi; Ma, Chao; Zhang, Wenzhe; Li, Xiaodong; Zhang, Wenting; Wu, Rongbo; Cheng, Xiangcan; Ali, Asad; Yang, Mingya; Zhu, Lixin; Xia, Ruixiang; Xu, Xiaoliang


    Attention on semiconductor nanocrystals have been largely focused because of their unique optical and electrical properties, which can be applied as light absorber and luminophore. However, the band gap and structure engineering of nanomaterials is not so easy because of their finite size. Here we demonstrate an approach for preparing ternary AgInS2 (AIS), quaternary AgZnInS (AZIS), AgInS2/ZnS and AgZnInS/ZnS nanocompounds based on cation exchange. First, pristine Ag2S quantum dots (QDs) with different sizes were synthesized in one-pot, followed by the partial cation exchange between In(3+) and Ag(+). Changing the initial ratio of In(3+) to Ag(+), reaction time and temperature can control the components of the obtained AIS QDs. Under the optimized conditions, AIS QDs were obtained for the first time with a cation disordered cubic phase and high photoluminescence (PL) quantum yield (QY) up to 32% in aqueous solution, demonstrating the great potential of cation exchange in the synthesis for nanocrystals with excellent optical properties. Sequentially, Zn(2+) ions were incorporated in situ through a second exchange of Zn(2+) to Ag(+)/In(3+), leading to distinct results under different reaction temperature. Addition of Zn(2+) precursor at room temperature produced AIS/ZnS core/shell NCs with successively enhancement of QY, while subsequent heating could obtain AZIS homogeneous alloy QDs with a successively blue-shift of PL emission. This allow us to tune the PL emission of the products from 483 to 675 nm and fabricate the chemically stable QDs core/ZnS shell structure. Based on the above results, a mechanism about the cation exchange for the ternary nanocrystals of different structures was proposed that the balance between cation exchange and diffusion is the key factor of controlling the band gap and structure of the final products. Furthermore, photostability and in vitro experiment demonstrated quite low cytotoxicity and remarkably promising applications in the

  10. 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


    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.

  11. Comparative analysis of cation/proton antiporter superfamily in plants

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Chuyu [ORNL; Yang, Xiaohan [ORNL; Xia, Xinli [Beijing Forestry University, China; Yin, Weilun [Beijing Forestry University, China


    The cation/proton antiporter superfamily is associated with the transport of monovalent cations across membranes. This superfamily was annotated in the Arabidopsis genome and some members were functionally characterized. In the present study, a systematic analysis of the cation/proton antiporter genes in diverse plant specieswas reported.We identified 240 cation/proton antiporters in alga, moss, and angiosperm. A phylogenetic tree was constructed showing these 240members are separated into three families, i.e., Na+/H+ exchangers, K+ efflux antiporters, and cation/H+ exchangers. Our analysis revealed that tandem and/or segmental duplications contribute to the expansion of cation/H+ exchangers in the examined angiospermspecies. Sliding windowanalysis of the nonsynonymous/synonymous substitution ratios showed some differences in the evolutionary fate of cation/proton antiporter paralogs. Furthermore, we identified over-represented motifs among these 240 proteins and foundmostmotifs are family specific, demonstrating diverse evolution of the cation/proton antiporters among three families. In addition, we investigated the co-expressed genes of the cation/proton antiporters in Arabidopsis thaliana. The results showed some biological processes are enriched in the co-expressed genes, suggesting the cation/proton antiporters may be involved in these biological processes. Taken together, this study furthers our knowledge on cation/proton antiporters in plants.

  12. Characterizing particle-scale equilibrium adsorption and kinetics of uranium(VI) desorption from U-contaminated sediments (United States)

    Stoliker, Deborah L.; Liu, Chongxuan; Kent, Douglas B.; Zachara, John M.


    Rates of U(VI) release from individual dry-sieved size fractions of a field-aggregated, field-contaminated composite sediment from the seasonally saturated lower vadose zone of the Hanford 300-Area were examined in flow-through reactors to maintain quasi-constant chemical conditions. The principal source of variability in equilibrium U(VI) adsorption properties of the various size fractions was the impact of variable chemistry on adsorption. This source of variability was represented using surface complexation models (SCMs) with different stoichiometric coefficients with respect to hydrogen ion and carbonate concentrations for the different size fractions. A reactive transport model incorporating equilibrium expressions for cation exchange and calcite dissolution, along with rate expressions for aerobic respiration and silica dissolution, described the temporal evolution of solute concentrations observed during the flow-through reactor experiments. Kinetic U(VI) desorption was well described using a multirate SCM with an assumed lognormal distribution for the mass-transfer rate coefficients. The estimated mean and standard deviation of the rate coefficients were the same for all distribution of mass-transfer rate coefficients, possibly caused by the abundance of microporous basaltic rock fragments.

  13. Multiple, simultaneous, independent gradients for a versatile multidimensional liquid chromatography. Part II: Application 2: Computer controlled pH gradients in the presence of urea provide improved separation of proteins: Stability influenced anion and cation exchange chromatography. (United States)

    Hirsh, Allen G; Tsonev, Latchezar I


    This paper details the use of a method of creating controlled pH gradients (pISep) to improve the separation of protein isoforms on ion exchange (IEX) stationary phases in the presence of various isocratic levels of urea. The pISep technology enables the development of computer controlled pH gradients on both cationic (CEX) and anionic (AEX) IEX stationary phases over the very wide pH range from 2 to 12. In pISep, titration curves generated by proportional mixing of the acidic and basic pISep working buffers alone, or in the presence of non-buffering solutes such as the neutral salt NaCl (0-1M), polar organics such as urea (0-8M) or acetonitrile (0-80 Vol%), can be fitted with high fidelity using high order polynomials which, in turn allows construction of a mathematical manifold %A (% acidic pISep buffer) vs. pH vs. [non-buffering solute], permitting precise computer control of pH and the non-buffering solute concentration allowing formation of dual uncoupled liquid chromatographic (LC) gradients of arbitrary shape (Hirsh and Tsonev, 2012 [1]). The separation of protein isoforms examined in this paper by use of such pH gradients in the presence of urea demonstrates the fractionation power of a true single step two dimensional liquid chromatography which we denote as Stability-Influenced Ion Exchange Chromatography (SIIEX). We present evidence that SIIEX is capable of increasing the resolution of protein isoforms difficult to separate by ordinary pH gradient IEX, and potentially simplifying the development of laboratory and production purification strategies involving on-column simultaneous pH and urea unfolding or refolding of targeted proteins. We model some of the physics implied by the dynamics of the observed protein fractionations as a function of both urea concentration and pH assuming that urea-induced native state unfolding competes with native state electrostatic interaction binding to an IEX stationary phase. Implications for in vivo protein

  14. Vi, de civiliserede

    DEFF Research Database (Denmark)

    Nyemann, Dorthe


    Vi har i årtier troet på, at mennesker under de rette omstændigheder kan lykkes med at leve i fred og fordragelighed med hinanden. Skal vi til at erkende, at også vores samfundsstrukturer kun er en tynd fernis ovenpå et utæmmeligt voldspotentiale og egoisme?......Vi har i årtier troet på, at mennesker under de rette omstændigheder kan lykkes med at leve i fred og fordragelighed med hinanden. Skal vi til at erkende, at også vores samfundsstrukturer kun er en tynd fernis ovenpå et utæmmeligt voldspotentiale og egoisme?...

  15. Isomerization of propargyl cation to cyclopropenyl cation ...

    Indian Academy of Sciences (India)

    step) for isomerization of the linear propargyl cation to the aromatic cyclopropenyl cation, also probing the phenomenon of solvation of this reaction by simple lone pair donors (NH3, H2O, H2S and HF) which bind to the substrate at two sites.

  16. Isomerization of propargyl cation to cyclopropenyl cation ...

    Indian Academy of Sciences (India)

    Abstract. This ab initio study examines two pathways (one concerted and the other two-step) for isomeri- zation of the linear propargyl cation to the aromatic cyclopropenyl cation, also probing the phenomenon of solvation of this reaction by simple lone pair donors (NH3, H2O, H2S and HF) which bind to the substrate at two.

  17. Predicting Organic Cation Sorption Coefficients: Accounting for Competition from Sorbed Inorganic Cations Using a Simple Probe Molecule. (United States)

    Jolin, William C; Goyetche, Reaha; Carter, Katherine; Medina, John; Vasudevan, Dharni; MacKay, Allison A


    With the increasing number of emerging contaminants that are cationic at environmentally relevant pH values, there is a need for robust predictive models of organic cation sorption coefficients (Kd). Current predictive models fail to account for the differences in the identity, abundance, and affinity of surface-associated inorganic exchange ions naturally present at negatively charged receptor sites on environmental solids. To better understand how organic cation sorption is influenced by surface-associated inorganic exchange ions, sorption coefficients of 10 organic cations (including eight pharmaceuticals and two simple probe organic amines) were determined for six homoionic forms of the aluminosilicate mineral, montmorillonite. Organic cation sorption coefficients exhibited consistent trends for all compounds across the various homoionic clays with sorption coefficients (Kd) decreasing as follows: KdNa+ > KdNH4+ ≥ KdK+ > KdCa2+ ≥ KdMg2+ > KdAl3+. This trend for competition between organic cations and exchangeable inorganic cations is consistent with the inorganic cation selectivity sequence, determined for exchange between inorganic ions. Such consistent trends in competition between organic and inorganic cations suggested that a simple probe cation, such as phenyltrimethylammonium or benzylamine, could capture soil-to-soil variations in native inorganic cation identity and abundance for the prediction of organic cation sorption to soils and soil minerals. Indeed, sorption of two pharmaceutical compounds to 30 soils was better described by phenyltrimethylammonium sorption than by measures of benzylamine sorption, effective cation exchange capacity alone, or a model from the literature (Droge, S., and Goss, K. Environ. Sci. Technol. 2013, 47, 14224). A hybrid approach integrating structural scaling factors derived from this literature model of organic cation sorption, along with phenyltrimethylammonium Kd values, allowed for estimation of Kd values for more

  18. Mineral Separation in a CELSS by Ion-exchange Chromatography (United States)

    Ballou, E. V.; Spitze, L. A.; Wong, F. W.; Wydeven, T.; Johnson, C. C.


    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.

  19. Étude de la technique d'échange ionique avec compétition. Cas du dépôt de platine sur support solide acide par échange cationique Research on the Ion Exchange Technique with Competition. Case of Platinum Deposit on a Solid Acid Support by Cation Exchange

    Directory of Open Access Journals (Sweden)

    Ribeiro F.


    Full Text Available Cet article présente une étude détaillée de la technique de dépôt de platine sur support acide par échange cationique avec compétition. Cette technique permet d'obtenir à la fois une dispersion quasi atomique et une répartition macroscopique homogène du métal sur la surface du solide. En l'absence de limitations diffusionnelles extra-granulaires, les résultats expérimentaux sont en bon accord avec les prévisions théoriques . This article is a detailed examination of the technique of depositing platinum on an acid support by cation exchange with compétition. This technique produces both a quasi-atomic dispersion and a homogeneous macroscopic distribution of the métal onthe surface of the solid. In the absence of extragranular diffusion limitations, experimental findings are in good agreement with theoretical predictions.

  20. Sorption and binary exchange of nitrate, sulfate, and uranium on an anion-exchange resin. (United States)

    Gu, Baohua; Ku, Yee-Kyoung; Jardine, Philip M


    Competitive ion-exchange reactions were studied on a strong-base anion-exchange resin to remove NO3- and uranium from a contaminated groundwater containing high levels of NO3- (approximately 140 mM), SO4(2-) (approximately 10 mM), and U(VI) (approximately 0.2 mM). Results indicate that although SO4(2-) carries divalent negative charges, it showed the least selectivity for sorption by the Purolite A-520E resin, which is functionalized with triethylamine exchange sites. Nitrate was the most strongly sorbed. Sorption selectivity followed the order of NO3- > Cl- > SO4(2-) under the experimental conditions. Nitrate competitively sorbed and displaced previously sorbed SO4(2-) in a column flow-through experiment and resulted in a high elution front of SO4(2-) in the effluent. Although the concentration of uranium in groundwater is orders of magnitude lower than that of NO3- or SO4(2-), it was found to be strongly sorbed by the anion-exchange resin. Because the most stable uranium species in oxic and suboxic environments is the UO2(2+) cation, its strong sorption by anion-exchange resins is hypothesized to be the result of the co-ion effect of NO3- by forming anionic UO2(NO3)3- complexes in the resin matrix. These observations point out a potential alternative remediation strategy that uses strong-base anion-exchange resins to remove uranium from this site-specific groundwater, which has a low pH and a relatively high NO3- concentration.

  1. 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


    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.

  2. Analyzing Solutions High in Total Dissolved Solids for Rare Earth Elements (REEs) Using Cation Exchange and Online Pre-Concentration with the seaFAST2 Unit; NETL-TRS-7-2017; NETL Technical Report Series; U.S. Department of Energy, National Energy Technology Laboratory: Albany, OR, 2017; p 32

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J. [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Science; Torres, M. [Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Science; Verba, C. [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States); Hakala, A. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)


    The accurate quantification of the rare earth element (REE) dissolved concentrations in natural waters are often inhibited by their low abundances in relation to other dissolved constituents such as alkali, alkaline earth elements, and dissolved solids. The high abundance of these constituents can suppress the overall analytical signal as well as create isobaric interferences on the REEs during analysis. Waters associated with natural gas operations on black shale plays are characterized by high salinities and high total dissolved solids (TDS) contents >150,000 mg/L. Methods used to isolate and quantify dissolved REEs in seawater were adapted in order to develop the capability of analyzing REEs in waters that are high in TDS. First, a synthetic fluid based on geochemical modelling of natural brine formation fluids was created within the Marcellus black shale with a TDS loading of 153,000 mg/L. To this solution, 1,000 ng/mL of REE standards was added based on preliminary analyses of experimental fluids reacted at high pressure and temperature with Marcellus black shale. These synthetic fluids were then run at three different dilution levels of 10, 100, and 1,000–fold dilutions through cation exchange columns using AG50-X8 exchange resin from Eichrom Industries. The eluent from the cation columns were then sent through a seaFAST2 unit directly connected to an inductively coupled plasma mass spectrometer (ICP-MS) to analyze the REEs. Percent recoveries of the REEs ranged from 80–110% and fell within error for the external reference standard used and no signal suppression or isobaric interferences on the REEs were observed. These results demonstrate that a combined use of cation exchange columns and seaFAST2 instrumentation are effective in accurately quantifying the dissolved REEs in fluids that are >150,000 mg/L in TDS and have Ba:Eu ratios in excess of 380,000.

  3. Degradation of fluoroquinolone antibiotics by ferrate(VI): Effects of water constituents and oxidized products. (United States)

    Feng, Mingbao; Wang, Xinghao; Chen, Jing; Qu, Ruijuan; Sui, Yunxia; Cizmas, Leslie; Wang, Zunyao; Sharma, Virender K


    The degradation of five fluoroquinolone (FQ) antibiotics (flumequine (FLU), enrofloxacin (ENR), norfloxacin (NOR), ofloxacin (OFL) and marbofloxacin (MAR)) by ferrate(VI) (Fe(VI)O4(2-), Fe(VI)) was examined to demonstrate the potential of this iron-based chemical oxidant to treat antibiotics in water. Experiments were conducted at different molar ratios of Fe(VI) to FQs at pH 7.0. All FQs, except FLU, were degraded within 2 min at [Fe(VI)]:[FQ] ≤ 20.0. Multiple additions of Fe(VI) improved the degradation efficiency, and provided greater degradation than a single addition of Fe(VI). The effects of anions, cations, and humic acid (HA), usually present in source waters and wastewaters, on the removal of FLU were investigated. Anions (Cl(-), SO4(2-), NO3(-), and HCO3(-)) and monovalent cations (Na(+) and K(+)) had no influence on the removal of FLU. However, multivalent cations (Ca(2+), Mg(2+), Cu(2+), and Fe(3+)) in water decreased the efficiency of FLU removal by Fe(VI). An increase in the ionic strength of the solution, and the presence of HA in the water, also decreased the percentage of FLU removed by Fe(VI). Experiments on the removal of selected FQs, present as co-existing antibiotics in pure water, river water, synthetic water and wastewater, were also conducted to demonstrate the practical application of Fe(VI) to remove the antibiotics during water treatment. The seventeen oxidized products (OPs) of FLU were identified using solid phase extraction-liquid chromatography-high-resolution mass spectrometry. The reaction pathways are proposed, and are theoretically confirmed by molecular orbital calculations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. and dioxouranium(vi)

    African Journals Online (AJOL)


    Thorium(IV) and uranium(VI) with atomic radii of 1.65 and .... to ν(NH) vibrations. Practically no effect on these frequencies after complexation precludes the possibility of metal-coordination at this group. The absorptions at 1600 ... observation suggests involvement of unsaturated nitrogen atoms of the two azomethine groups.

  5. Cation-alkane interaction. (United States)

    Premkumar, J Richard; Sastry, G Narahari


    Ab initio computations, up to CCSD(T)/CBS on model systems, and MP2/cc-pVTZ and DFT calculations are performed on cation-alkane and cation-alkene complexes, cation = Li(+), Na(+), Be(2+), Mg(2+), Ca(2+), Cu(+) and Zn(2+); alkane = C(n)H2(n+2) (n = 1-10) and C6H12; and alkene = C2H4 and C6H6. Density functional theory-symmetry adapted perturbation theory (DFT-SAPT) calculations reveal that the cation-alkane interactions are predominantly constituted of induction component. The dramatic modulation of the strength of their interaction and the topological features obtained from atoms in molecules (AIM) analysis are consistent with the characteristics of a typical noncovalent interaction. In contrast to many of the conventional noncovalent interactions, cation-alkane interactions are substantially strong and are comparable in strength to the well studied cation-π interactions.

  6. II-VI semiconductor compounds

    CERN Document Server


    For condensed matter physicists and electronic engineers, this volume deals with aspects of II-VI semiconductor compounds. Areas covered include devices and applications of II-VI compounds; Co-based II-IV semi-magnetic semiconductors; and electronic structure of strained II-VI superlattices.

  7. Effects of Copper Exchange Levels on Complexation of Ammonia in ...

    African Journals Online (AJOL)


    Cation exchange, catalysis, copper, complexation, copper ammines. 1. Introduction. Copper-exchanged zeolites ... characterization of cation-exchanged zeolites is ammonia.7. Ammonia is small enough (ca. 3.70 × 3.99 .... quartz glass sample cuvettes and the diffuse reflectance spec- troscopy measurements obtained from ...

  8. Removal of cesium ions from clays by cationic surfactant intercalation. (United States)

    Park, Chan Woo; Kim, Bo Hyun; Yang, Hee-Man; Seo, Bum-Kyoung; Moon, Jei-Kwon; Lee, Kune-Woo


    We propose a new approach to remediate cesium-contaminated clays based on intercalation of the cationic surfactant dodecyltrimethylammonium bromide (DTAB) into clay interlayers. Intercalation of DTAB was found to occur very rapidly and involved exchanging interlayer cations. The reaction yielded efficient cesium desorption (∼97%), including of a large amount of otherwise non-desorbable cesium ions by cation exchange with ammonium ions. In addition, the intercalation of DTAB afforded an expansion of the interlayers, and an enhanced desorption of Cs by cation exchange with ammonium ions even at low concentrations of DTAB. Finally, the residual intercalated surfactants were easily removed by a decomposition reaction with hydrogen peroxide in the presence of Cu 2+ /Fe 2+ catalysts. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. VI Nukitsa konkurss

    Index Scriptorium Estoniae


    VI Nukitsa konkursi auhinnad: Kirjanikud: I - Henno Käo ("Kusagil mujal"); II - Aidi Vallik ("Kuidas elad, Ann?"); III - Artur Jurin ("Piletijaht: uued segadused Kilulibeda teel"). Kunstnikud: I - Karel Korp (Leelo Tungla ja Karel Korbi "Tema amet"); II - Edgar Valter ("Kuidas õppida vaatama?"); III - Artur Jurin - ("Piletijaht: uued segadused Kilulibeda teel"). Täiskasvanute küsitluse võitis nii teksti kui piltidega Ene-Maris Tali ja Tarmo Tali "Tähtraamat. Aastaring Maarjamaal"

  10. Cinética e equilíbrio de adsorção dos oxiânions Cr (VI, Mo (VI e Se (VI pelo sal de amônio quaternário de quitosana Kinetics and equilibrium of adsorption of oxyanions Cr (VI, Mo (VI and Se (VI by quaternary ammonium chitosan salt

    Directory of Open Access Journals (Sweden)

    Viviane A. Spinelli


    one gram of cross-linked quaternary chitosan salt adsorbed 68.3 mg of chromium, 63.4 mg of molybdenum and 90.0 mg of selenium. The adsorption process followed a pseudo second-order kinetic rate equation and the equilibrium regarding the three ions was reached after 200 minutes. The studies from X-ray dispersive energy showed that the main adsorption mechanism is ionic exchange among Cl- groups on the polymer surface by oxyanions from solution and the anionic exchanger showed the following selectivity order: Cr (VI > Mo (VI > Se (VI.

  11. New approach in modeling Cr(VI) sorption onto biomass from metal binary mixtures solutions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chang [College of Environmental Science and Engineering, Anhui Normal University, South Jiuhua Road, 189, 241002 Wuhu (China); Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Fiol, Núria [Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Villaescusa, Isabel, E-mail: [Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Poch, Jordi [Applied Mathematics Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain)


    In the last decades Cr(VI) sorption equilibrium and kinetic studies have been carried out using several types of biomasses. However there are few researchers that consider all the simultaneous processes that take place during Cr(VI) sorption (i.e., sorption/reduction of Cr(VI) and simultaneous formation and binding of reduced Cr(III)) when formulating a model that describes the overall sorption process. On the other hand Cr(VI) scarcely exists alone in wastewaters, it is usually found in mixtures with divalent metals. Therefore, the simultaneous removal of Cr(VI) and divalent metals in binary mixtures and the interactive mechanism governing Cr(VI) elimination have gained more and more attention. In the present work, kinetics of Cr(VI) sorption onto exhausted coffee from Cr(VI)–Cu(II) binary mixtures has been studied in a stirred batch reactor. A model including Cr(VI) sorption and reduction, Cr(III) sorption and the effect of the presence of Cu(II) in these processes has been developed and validated. This study constitutes an important advance in modeling Cr(VI) sorption kinetics especially when chromium sorption is in part based on the sorbent capacity of reducing hexavalent chromium and a metal cation is present in the binary mixture. - Highlights: • A kinetic model including Cr(VI) reduction, Cr(VI) and Cr(III) sorption/desorption • Synergistic effect of Cu(II) on Cr(VI) elimination included in the model • Model validation by checking it against independent sets of data.


    Energy Technology Data Exchange (ETDEWEB)



    This report describes batch and ion exchange column laboratory scale studies investigating ex situ methods to remove chromate (chromium [VI]), nitrate (NO{sub 3}{sup -}) and uranium (present as uranium [VI]) from contaminated Hanford site groundwaters. The technologies investigated include: chemical precipitation or coprecipitation to remove chromate and uranium; and anion exchange to remove chromate, uranium and nitrate. The technologies investigated were specified in the 100-HR-3 Groundwater Treatability Test Plan. The method suggested for future study is anion exchange.


    African Journals Online (AJOL)

    SEI Joseph

    l'étude de nombreux paramètres (concentration, température, l'ajout de la bentonite), nous avons démontré que les boues ... haute densité (PEHD) et des matériaux argileux spécifiques de type bentonite. A ce jour ..... [4] - K. VERBURG AND P. BAVEYE “Hysteresis in the binary exchange of cations on 2:1 clay minerals : a.

  14. Role of metal d states in II-VI semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Wei, S.; Zunger, A.


    All-electron band-structure calculations and photoemission experiments on II-VI semiconductors both exhibit a metal d subband inside the main valence band. It has nevertheless been customary in pseudopotential and tight-binding approaches to neglect the metal d band by choosing Hamiltonian parameters which place this band inside the chemically inert atomic cores. Using all-electron self-consistent electronic-structure techniques (which treat the outermost d electrons on the same footing as other valence electrons) and comparing the results to those obtained by methods which remove the d band from the valence spectrum, we study their effects on valence properties. For II-VI semiconductors we find that p-d repulsion and hybridization (i) lower the band gaps, (ii) reduce the cohesive energy, (iii) increase the equilibrium lattice parameters, (iv) reduce the spin-orbit splitting, (v) alter the sign of the crystal-field splitting, (vi) increase the valence-band offset between common-anion II-VI semiconductors, and (vii) modify the charge distributions of various II-VI systems and their alloys. p-d repulsion is also shown to be responsible for the occurrence of deep Cu acceptor levels in II-VI semiconductors (compared with shallow acceptors of Zn in III-V), for the anomalously small band gaps in chalcopyrites, and for the negative exchange splitting in ferromagnetic MnTe.

  15. Separation of cationic aracyl derivatives of betaines and related compounds. (United States)

    Storer, Malina K; McEntyre, Christopher J; Lever, Michael


    Cationic aracyl esters of betaines can be formed by alkylation with aracyl halides or trifluoromethanesulfonates. HPLC on a non-endcapped strong cation exchange (SCX) column gave high retention of these derivatives. Cation exchange HPLC may be carried out on a normal-phase (silica or alumina) column using a polar organic solvent (acetonitrile, propan-2-ol) containing an aqueous buffer with an organic cation and a hydrophilic anion. Selectivity is affected by the choice of organic solvent and buffer, e.g. alcohols decrease the retention times of hydroxybetaines such as carnitine. Retention is reduced by increasing the water content and the buffer concentration. Capillary electrophoresis migration times are affected by the choice of buffer anion, with low pH citrate buffers favoured.

  16. Vi tror, vi forstår hinanden, men det gør vi ikke

    DEFF Research Database (Denmark)

    Boysen, Mikkel Snorre Wilms


    Vores verdensbillede er baseret på en tro på, at vi forstår hinanden. Men meget tyder på, at denne tro snarere er en illusion. Derfor må vi indstille os på, at der skal en særlig indsats til, hvis vi skal kunne forstå vores omverden og menneskene i den......Vores verdensbillede er baseret på en tro på, at vi forstår hinanden. Men meget tyder på, at denne tro snarere er en illusion. Derfor må vi indstille os på, at der skal en særlig indsats til, hvis vi skal kunne forstå vores omverden og menneskene i den...

  17. Determination of common inorganic anions and cations by non-suppressed ion chromatography with column switching. (United States)

    Amin, Muhammad; Lim, Lee Wah; Takeuchi, Toyohide


    An ion chromatography (IC) method has been proposed for the determination of seven common inorganic anions (F(-), H(2)PO(4)(-), NO(2)(-), Cl(-), Br(-), NO(3)(-), and SO(4)(2-)) and/or five common inorganic 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 a single 10-port switching valve. The 10-port valve was switched for the separation of either cations or anions in a single chromatographic run. When 1.0mM trimellitic acid (pH 2.94) was used as the eluent, the seven anions and the five cations could be separated on the anion-exchange column and the cation-exchange column, respectively. The elution order was found to be F(-)anions and Na(+)cations. Complete separation of the above anions or cations was demonstrated within 35min each. Detection limits calculated at S/N=3 were 0.05-0.58ppm (mg/l) for the anions and 0.05-0.38ppm for the cations, whereas repeatability values were below 2.26, 2.76, and 2.90% for peak height, peak area and retention time, respectively. The method was successfully applied to the determination of inorganic anions and cations in river water samples.

  18. Role of extracellular cations in cell motility, polarity, and chemotaxis

    Directory of Open Access Journals (Sweden)

    Soll D


    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

  19. Identifi cation of Sectarianism

    Directory of Open Access Journals (Sweden)

    Martinovich Vladimir


    Full Text Available «New religious movements and society» is traditionally one of the most sophisticated topics in the area of new religions studies. Its problem field is so huge that up to now by far not all important research themes where even touched by scientists from all over the world. The problem of the process of the identification of sectarianism by diff erent societal institutions is one of such untouched themes that is taken as the main subject of this article. This process by itself is an inseparable part of the every societal deliberate reaction to the very existence of unconventional religiosity, its unstructured and mainly structured types. The focal point of the article is step-by-step analysis of the general structure elements of the process of the identification of sectarianism without any reference to the specific time and place of its flow. Special attention is paid to the analysis of the subjects of the identification of sectarianism, to the criteria for religious groups to be qualified as new religious movements, and to the specific features of the process of documents filtration. The causes of selective perception of sectarianism are disclosed. Some main consequences and unpredictable outcomes of the process of the identification of sectarianism are described.

  20. Sorption of the organic cation metoprolol on silica gel from its aqueous solution considering the competition of inorganic cations. (United States)

    Kutzner, Susann; Schaffer, Mario; Börnick, Hilmar; Licha, Tobias; Worch, Eckhard


    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. ViFiLite Project (United States)

    National Aeronautics and Space Administration — ViFiLite is a wireless infrastructure that utilizes the advantages of a V-band technology in supporting data gathering for structural health monitoring as well as...

  2. Skal vi have flere krondyr?

    DEFF Research Database (Denmark)

    Pedersen, Jens Christian


    Vi kunne have væsentligt flere krondyr i den danske natur end vi har i øjeblikket. Den primære årsag er jagt. Det viser en ny undersøgelse fra Danmarks Miljøundersøgelser ved Aarhus Universitet. Bestanden af krondyr er ganske vist steget meget siden 1970, men der er både plads og føde til mange...

  3. Improvement of Chromium(VI) Extraction from Acidic Solutions Using a Poly(vinyl chloride)-based Polymer Inclusion Membrane with Aliquat 336 as the Carrier. (United States)

    Kagaya, Shigehiro; Maeno, Tomonori; Ito, Kazuma; Gemmei-Ide, Makoto; Cattrall, Robert W; Kolev, Spas D


    An important reason for the inefficient extraction of Cr(VI) from its acidic solutions into polymer inclusion membranes (PIMs), consisting of poly(vinyl chloride) as the base-polymer and Aliquat 336 as the carrier, was found to be associated with the leaching of Aliquat 336 from the PIMs into the solutions, where it subsequently reduced the anionic Cr(VI) species to cationic Cr(III) species. The PIM extraction efficiency for Cr(VI) was significantly improved by the addition of NaNO3 to the solutions, which suppressed the leaching of Aliquat 336 and the reduction of Cr(VI) to Cr(III).

  4. Reduction of trace quantities of chromium(VI by strong acids

    Directory of Open Access Journals (Sweden)

    Pezzin Sérgio H


    Full Text Available The chemical behavior of Cr(VI at low concentrations (10-4 to 10-7 mol L-1 in several strong acids was studied using high specific activity 51Cr(VI as a tracer. The speciation of the products from these systems was carried out by ion exchange chromatography with stepwise elution. The results show that trace quantities of Cr(VI, monitored by means of radiochromium (51Cr, are reduced in the presence of mineral acids such as perchloric, hydrochloric, hydrofluoric, sulfuric, nitric and trifluoromethanesulfonic acids, even in the absence of conventional reducing agents, producing different measureable Cr(III species, depending on the acid anion. Detailed studies of the reduction of low concentrations of Cr(VI with nitric acid have shown that the relative rate of reduction increases as the concentration of the acid increases or as the concentration of the Cr(VI decreases.

  5. Studies on Municipal Solid Wastes Dumping on Soil Anions, Cations ...

    African Journals Online (AJOL)

    Similarly dumpsite soil nitrate level, percentage organic carbon, organic matter, sulphate and phosphate ions were significantly (P<0.05) increased with increased waste dumping. All the exchangeable cations and trace metals concentrations investigated were higher (P<0.05) than control levels. However, while the ...

  6. Atmospheric CO2 enrichment facilitates cation release from soil. (United States)

    Cheng, L; Zhu, J; Chen, G; Zheng, X; Oh, N-H; Rufty, T W; Richter, D deB; Hu, S


    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.

  7. Tetrapotassium cis-dioxido-trans-bis(sulfato-κOsulfato(κ2O,O′molybdate(VI

    Directory of Open Access Journals (Sweden)

    Rolf W. Berg


    Full Text Available The title compound, K4[MoVIO2(SO43], was precipitated from a melt of molybdenum(VI oxide and potassium sulfate in potassium disulfate. The compound contains monomeric [MoVIO2(SO43]4− anions, with the MoVI atom, both oxide ligands, and the S atom and both ligating O atoms of the bidentate sulfate group lying on a crystallographic mirror plane. One of the potassium cations is nine-coordinate, while the other is eight-coordinate.

  8. Fine structure of charge exchange lines observed in laboratory plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ida, K.; Nishimura, S. [National Inst. for Fusion Science, Nagoya (Japan); Kondo, K.


    The influence of the fine structure of charge exchange lines appears only at the plasma edge or in the recombining phase where the ion temperature is low enough. The observed spectra in Li III and C VI are consistent with the sum of fine-structure components populated by statistical weights (assuming complete l-mixing) not by direct charge exchange cross sections. Some discrepancy was observed in the intensity ratio of fine-structure components between the observation and calculation for C VI in the recombining phase. The fine-structure of charge exchange lines gives an apparent Doppler shift in plasma rotation velocity measurement using charge exchange spectroscopy. (author)

  9. Characterization of uranium(VI) sorption by organobentonite

    Energy Technology Data Exchange (ETDEWEB)

    Majdan, Marek, E-mail: [Faculty of Chemistry, Maria Curie Sklodowska University, 20-031 Lublin (Poland); Pikus, Stanislaw; Gajowiak, Agnieszka; Gladysz-Plaska, Agnieszka [Faculty of Chemistry, Maria Curie Sklodowska University, 20-031 Lublin (Poland); Krzyzanowska, Halina; Zuk, Jerzy [Institute of Physics, Maria Curie Sklodowska University, 20-031 Lublin (Poland); Bujacka, Monika [Faculty of Chemistry, Maria Curie Sklodowska University, 20-031 Lublin (Poland)


    The U(VI) sorption on the bentonite modified by hexadecyltrimethylammonium bromide (HDTMA) was studied in the concentration range: 0.0001-0.001 mol/dm{sup 3} in the aqueous phase and in the pH range: 3-10. The experiments concerning the pH influence on the molar absorption coefficient c{sub b} of U(VI) in the bentonite phase showed that the species: UO{sub 2}{sup 2+}, UO{sub 2}(OH){sup +}, UO{sub 2}(OH){sub 2} UO{sub 2}(OH){sub 3}{sup -}, UO{sub 2}(OH){sub 4}{sup 2-}, (UO{sub 2}){sub 3}(OH){sub 5}{sup +}, (UO{sub 2}){sub 3}(OH){sub 7}{sup -}, present in the aqueous phase, are responsible for uranium sorption. Their sorption parameters K were determined and it is evident that for higher concentrations of HDTMA{sup +} cations in the bentonite phase, i.e. for b96-b157 bentonite, the presence of anionic species: UO{sub 2}(OH){sub 3}{sup -}, UO{sub 2}(OH){sub 4}{sup 2-}, and (UO{sub 2}){sub 3}(OH){sub 7}{sup -} in the aqueous phase results in the increase of U(VI) molar absorption coefficient c{sub b} in the sorbent phase.

  10. Protostars and Planets VI (United States)

    Beuther, Henrik; Klessen, Ralf S.; Dullemond, Cornelis P.; Henning, Thomas

    star and planet formation. They are used by students to dive into new topics, and they are much valued by experienced researchers as a comprehensive overview of the field with all its interactions. We hope that you will enjoy reading (and learning from) this book as much as we do. The organization of the Protostars and Planets conference was carried out in close collaboration between the Max Planck Institute for Astronomy and the Center for Astronomy of the University Heidelberg, with generous support from the German Science Foundation. This volume is a product of effort and care by many people. First and foremost, we want to acknowledge the 250 contributing authors, as it is only due to their expertise and knowledge that such a comprehensive review compendium in all its depth and breadth is possible. The Protostars and Planets VI conference and this volume was a major undertaking, with support and contributions by many people and institutions. We like to thank the members of the Scientific Advisory Committee who selected the 38 teams and chapters out of more than 120 submitted proposals. Similarly, we are grateful to the reviewers, who provided valuable input and help to the chapter authors. The book would also not have been possible without the great support of Renée Dotson and other staff from USRA’s Lunar and Planetary Institute, who handled the detailed processing of all manuscripts and the production of the book, and of Allyson Carter and other staff from the University of Arizona Press. We are also grateful to Richard Binzel, the General Editor of the Space Science Series, for his constant support during the long process, from the original concept to this final product. Finally, we would like to express a very special thank you to the entire conference local organizing committee, and in particular, Carmen Cuevas and Natali Jurina, for their great commitment to the project and for a very fruitful and enjoyable collaboration.

  11. Bioprospecting of gum kondagogu (Cochlospermum gossypium) for bioremediation of uranium (VI) from aqueous solution and synthetic nuclear power reactor effluents. (United States)

    Sashidhar, R B; Selvi, S Kalaignana; Vinod, V T P; Kosuri, Tanuja; Raju, D; Karuna, R


    An ecofriendly green chemistry method using a natural biopolymer, Gum Kondagogu (GK) for the removal of U (VI) from aqueous, simulated nuclear effluents was studied. The adsorption characteristic of GK towards U (VI) from aqueous solution was studied at varied pH, contact time, adsorbent dose, initial U (VI) concentration and temperature using UV-Visible spectroscopy and ICP-MS. Maximum adsorption was seen at pH 4, 0.1% GK with 60 min contact time at room temperature. The GK- U (VI) composite was characterized by FT-IR, zeta potential, TEM and SEM-EDAX. The Langmuir isotherm was found to be 487 mg of U (VI) g(-1) of GK. The adsorption capacity and (%) of U (VI) was found to be 490 ± 5.4 mg g(-1) and 98.5%. Moreover adsorption of U (VI) by GK was not influenced by other cations present in the simulated effluents. The adsorbed U (VI) was efficiently stripped from composite using 1 M HCl. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Immuno-fluorescence based Vi capsular polysaccharide detection for specific recognition of Salmonella enterica serovar Typhi in clinical samples. (United States)

    Pandey, Satish K; Vinayaka, Aaydha C; Rishi, Dharam B; Rishi, Praveen; Suri, C Raman


    Typhoid fever is a life threatening bacterial infection that remains a major global health concern. This continued high burden associated with significant morbidity and mortality rate demands specific and rapid detection technique. This work reports a new sandwich type fluorescence immunoassay format using polymyxin B, a cationic receptor molecule, as a binder agent while anti-Vi antibody served as the capturing agent for specifically detecting Salmonella enterica serovar Typhi. Anti-Vi IgG antibody raised against Vi-BSA conjugate revealed affinity of 7.779nM(-1) signifying immunodominancy of O-acetyls groups in Vi polysaccharide. The detection limit of the developed assay was around 10(1) cellsmL(-1) of Vi expressing Salmonella enterica serovar Typhi with a correlation coefficient (R(2)) equal to 0.97. Positive response obtained for all the tested serovar Typhi clinical isolates as well as the pathogen spiked blood samples recommended specificity and accuracy of Vi antigen as a biomarker during typhoid fever. The intra- and inter-assay precision with Vi spiked samples were satisfactory revealing coefficient of variance (CV%) with a mean of 4.05% and 5.97% respectively. This may be the novel attempt and constructive report on the fluorescence based detection of Vi antigen of serovar Typhi in the epidemic as well as pandemic outbreaks. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. VI Tallinna arhitektuuritriennaal / Leonhard Lapin

    Index Scriptorium Estoniae

    Lapin, Leonhard, 1947-


    15.-17. IX Tallinnas Niguliste kirikus toimuval VI Tallinna arhitektuuritriennaalil esinevad inglise arhitektuurikriitik Peter Davey, šveitsi arhitekt Peter Zumthor, soome arhitekt Juha Leviskä, eesti arhitekt Vilen Künnapu, eesti kunstiajaloolane Juhan Maiste jt. Külastatakse KUMU, tutvutab autor Pekka Vapaavuori

  14. (VI) oxide in acetic acid

    African Journals Online (AJOL)

    The oxidation of cyclohexene by chromium (VI) oxide in aqueous and acetic media was studied. The reaction products were analysed using infra red (IR) and gas chromatography coupled with mass (GC/MS) spectroscopy. The major products of the oxidation reaction in acetic acid medium were cyclohexanol, ...

  15. Enhancement strategies for Cu(II), Cr(III) and Cr(VI) remediation by a variety of seaweed species. (United States)

    Murphy, V; Hughes, H; McLoughlin, P


    Various chemical treatments have been applied to six brown, red and green seaweed species with a view to enhancing their metal removal for Cu(II), Cr(III) and Cr(VI). Treatment with acetone resulted in the greatest enhancement for both cationic and anionic species with relatively low mass losses (15-35%), indicating its low risk to biomass operational stability. Cation binding was increased by 69%, while the total Cr removal was augmented by 15%. Cr(VI) binding was shown to be an adsorption-coupled reduction, whereby Cr(VI) was bound to the biomass surface at pH 2 and subsequently reduced to Cr(III). Acetone treatment also resulted in biomasses that were capable of converting up to 83% of Cr(VI) in solution to Cr(III). Blocking of carboxyl and amino functionalities had significant negative effects both on total Cr removal as well as percentage conversion of Cr(VI) to Cr(III). Results therefore indicated the significant role played by these moieties in metal binding to these seaweeds. Potentiometric titrations displayed agreement between the degree of esterification and the decrease in Cu(II) removal for Ulva spp. and Polysiphonia lanosa. FTIR analysis identified changes in biomass functionality and availability after chemical modification, the results of which were in agreement with metal removal studies. In conclusion, these biosorbents represent suitable candidates to replace conventional removal technologies for metal bearing wastewaters, in particular for the detoxification of hazardous Cr(VI) waste streams.

  16. Impact of Cation form on Structure/Function Relationships of Perflurosulfonic Acid Ionomers (United States)

    Kusoglu, Ahmet; Shi, Shouwen; Tesfaye, Meron; Weber, Adam

    Perfluorosulfonic-acid (PFSA) ionomers are widely used as ion-exchange solid-electrolytes in electrochemical devices, where their behavior are influenced by the interactions among its sulfonate groups, mobile cations, and water. The properties of a PFSA depends on its hydration, which drives its phase-separated morphology and controls the extent of sulfonate-cation interaction. Thus, cation-form and hydration collectively affect the structure/transport relationship, yet their interplay is still not well known. To elucidate this interplay, water uptake and conductivity of cation-exchanged PFSA are studied at various relative humidities (RHs) and in water, which are then correlated with mechanical properties and nanostructure. With increasing cation size and valence, the modulus increases, while swelling and conductivity decreases. The extent to which the cations impact the conductivity depends on hydration; at low RH the controlling factor is the cation (interactions), while with increasing RH, the key factor becomes water (swelling), although it is also controlled by the cations. Changes in conductivity with cations and RH are analyzed to establish a universal conductivity-hydration correlation, by accounting for charge density and water content.

  17. 29 CFR 1926.1126 - Chromium (VI). (United States)


    ... 29 Labor 8 2010-07-01 2010-07-01 false Chromium (VI). 1926.1126 Section 1926.1126 Labor... Chromium (VI). (a) Scope. (1) This standard applies to occupational exposures to chromium (VI) in all forms... objective data demonstrating that a material containing chromium or a specific process, operation, or...

  18. 29 CFR 1915.1026 - Chromium (VI). (United States)


    ... 29 Labor 7 2010-07-01 2010-07-01 false Chromium (VI). 1915.1026 Section 1915.1026 Labor... § 1915.1026 Chromium (VI). (a) Scope. (1) This standard applies to occupational exposures to chromium (VI... cement; or (4) Where the employer has objective data demonstrating that a material containing chromium or...

  19. Barter exchanges

    DEFF Research Database (Denmark)

    Sudzina, Frantisek

    Although barter is often perceived as something that proceeded money, barter is still used. The focus of the paper is on barter exchanges. Barter exchanges are used both in developing countries as well as in developed countries (including the U.S.). They are used by both organizations...... and individuals. They usually allow to exchange good but some include also services. Some exchanges allow only for bi-directional barter, i.e. when only two parties are involved in the exchange. But probably most of the barter exchanges use barter money; this makes it easier to exchange goods and services...

  20. Synthesis and application of magnetic hydrogel for Cr(VI) removal from contaminated water

    KAUST Repository

    Tang, Samuel C N


    Many magnetic adsorbents reported in the literature, such as iron oxides, for Cr(VI) removal have been found effective only in low pH environments. Moreover, the application of polymeric hydrogels on heavy metal removal has been hindered by difficulties in separation by filtration. In this study, a magnetic cationic hydrogel was synthesized for Cr(VI) removal from contaminated water, making use of the advantages of magnetic adsorbents and polymeric hydrogels. The magnetic hydrogel was produced by imbedding 10-nm γ-Fe2O 3 nanoparticles into the polymeric matrix via radical polymerization. Characterization of the hydrogel was undertaken with Fourier transform infrared and vibrating sample magnetometer; swelling properties were tested and anionic adsorption capacity was evaluated. The magnetic hydrogel showed a superior Cr(VI) removal capacity compared to commercial products such as MIEX®. Cr(VI) removal was independent of solution pH. Results show that Cr(VI) removal kinetics was improved drastically by grinding the bulk hydrogel into powder form. At relevant concentrations, common water anions (e.g., Cl-, SO4 2-, PO4 3-) and natural organic matter did not exhibit significant inhibition of Cr(VI) adsorption onto the hydrogel. Results of vibrating sample magnetometer indicate that the magnetic hydrogel can be easily separated from treatment systems. Regeneration of the magnetic hydrogel can be easily achieved by washing the Cr(VI)-loaded hydrogel with 0.5 M NaCl solution, with a recovery rate of about 90% of Cr(VI). © Copyright 2010, Mary Ann Liebert, Inc. 2010.

  1. Catalysis using hydrous metal oxide ion exchanges (United States)

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.


    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.

  2. Catalysis using hydrous metal oxide ion exchangers (United States)

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.


    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.

  3. Hvad bruger vi tiden til?

    DEFF Research Database (Denmark)

    Brichet, Nathalia Sofie; Hastrup, Frida


    I denne artikel kaster vi et antropologisk blik på samtidsarkæologi ved at diskutere måder, hvorpå antropologiske analyser kan adressere tid, fortidige hændelser og historiske processer. Vi argumenterer for, at en radikal nutidsorientering er en afgørende kvalitet ved det antropologiske feltarbej...... komplicerer en ide om fortidige (gamle eller nyere) objekter som nogle, der kan udgraves......., hvis sigte det er løbende at generere sit materiale nu og her med henblik på at skabe nye forståelser, historier og forslag til mangeartede sammenhænge. En implikation af dette er, at uanset hvor ’historisk’ et antropologisk materiale end måtte være, må det altid ses som samtidigt og ufærdigt, hvilket...

  4. Adsorption studies for the removal of Cr(VI) ion from aqueous solution

    African Journals Online (AJOL)

    The adsorption characteristics of Cr(VI) in the form of Cr2O7(-2) ion from aqueous solution onto synthetic exchanger Amberlite IRA 400(Cl) resin was studied from UV – visible spectrphotometric measurement using DPC at 580nm. The efficiency of the adsorbent was judged from the variation of the % adsorption with (i) ...

  5. High-field Faraday rotation in II-VI-based semimagnetic semiconductors

    NARCIS (Netherlands)

    Savchuk, AI; Fediv, [No Value; Nikitin, PI; Perrone, A; Tatzenko, OM; Platonov, VV

    The effects of d-d exchange interaction have been studied by measuring high-field Faraday rotation in II-VI-based semimagnetic semiconductors. For Cd1-xMnxTe crystals with x = 0.43 and at room temperature a saturation in magnetic field dependence of the Faraday rotation has been observed. In the

  6. Leaching of Co and Cs from spent ion exchange resins in cement ...

    Indian Academy of Sciences (India)



    Aug 22, 2003 ... Abstract. The leaching rate of 60Co and 137Cs from the spent cation exchange resins in cement–bentonite matrix has been studied. The solidification matrix was a standard Portland cement mixed with 290–350 (kg/m3) spent cation exchange resins, with or without 2–5% of bentonite clay. The leaching ...

  7. Leaching of 60 Co and 137 Cs from spent ion exchange resins in ...

    Indian Academy of Sciences (India)

    The leaching rate of 60Co and 137Cs from the spent cation exchange resins in cement–bentonite matrix has been studied. The solidification matrix was a standard Portland cement mixed with 290–350 (kg/m3) spent cation exchange resins, with or without 2–5% of bentonite clay. The leaching rates from the ...

  8. Adsorption of hexavalent chromium on cationic cross-linked starches of different botanic origins. (United States)

    Klimaviciute, Rima; Bendoraitiene, Joana; Rutkaite, Ramune; Zemaitaitis, Algirdas


    The influence of origin of native starch used to obtain cationic cross-linked starch (CCS) on the adsorption of Cr(VI) onto CCS has been investigated. CCS granule size is influenced by the botanic source of native starch. The equilibrium adsorption of Cr(VI) onto CCS was described by the Langmuir, Freundlich, Dubinin-Radushkevich and Temkin models. The more equal the adsorption energy of the quaternary ammonium groups in CCS granule as indicated by low value of change of Temkin adsorption energy DeltaE(T) the greater amount of Cr(VI) was adsorbed onto CCS. The value of DeltaE(T) decreased and sorption capacity of CCS increased with the decrease of CCS granule size and with the increase of number of amorphous regions in CCS granules. The affinity of dichromate anions increases and adsorption proceeds more spontaneously when Cr(VI) is adsorbed onto more amorphous CCS. Adsorption process of Cr(VI) onto such CCS is more exothermic and order of system undergoes major changes during adsorption. After the adsorption on CCS Cr(VI) could be regenerated by incineration at temperature of 800 degrees C. Copyright 2010 Elsevier B.V. All rights reserved.

  9. Hydrothermal Transformation of Natural Zeolite from Ende-NTT and Its Application as Adsorbent of Cationic Dye

    National Research Council Canada - National Science Library

    Ngapa, Yulius Dala; Sugiarti, Sri; Abidin, Zaenal


    .... The natural zeolite produced synthetic NaP1 and synthetic Faujasite. Based on the research results, the synthesis of zeolite by the hydrothermal method can enhance the adsorption capacity and Cation Exchange Capacity (CEC...

  10. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu


    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  11. Synthetic cation-selective nanotube: permeant cations chaperoned by anions. (United States)

    Hilder, Tamsyn A; Gordon, Dan; Chung, Shin-Ho


    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.

  12. Cation exchange applications of synthetic tobermorite for the ...

    Indian Academy of Sciences (India)


    Although the ordinary portland cement (OPC) which is often used in waste management operations alone holds negligible amounts of Cs+ and Sr2+, ... Conditioning is the waste management step in which radioactive waste is immobilized ..... Gour University, Sagar for providing laboratory facilities and Dr J P Shrivastava, ...

  13. Fabrication of Cationic Exchange Polystyrene Nanofibers for Drug ...

    African Journals Online (AJOL)

    Method: The nanofibers were prepared from 15% w/v polystyrene solution in dimethylacetamide (DMAc) containing 0.025 %w/v tetrabutylammonium bromide (TBAB) using electrospinning technique, followed by crosslinking with sulfuric acid/formaldehyde in a ratio ranging from 100/0 to 50/50 v/v and sulfonation in sulfuric ...

  14. an assessment of cation-exchange capability of the carboxylated ...

    African Journals Online (AJOL)


    Department of Chemistry, University of Dar es Salaam, Box 35061, Dar es Salaam, Tanzania. (Received July 1, 2004; ... Petrochemicals cannot be sustained due to their high cost and depletion rates that lead ... coatings and brake linings [2, 4, 5], CNSL-based spherical polymer particles for adsorption and immobilization [6] ...


    African Journals Online (AJOL)

    B. S. Chandravanshi

    indicating a purer extract. KEY WORDS: Khat alkaloids, Solid phase extraction, Liquid-liquid extraction, HPLC, Genevac. INTRODUCTION. Khat (Catha edulis Vahl. Endl.) is an evergreen shrub or tree belonging to the Celastraceae family. Although the plant originates from Ethiopia, it occurs in Kenya, Malawi, Uganda,.


    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...

  17. Exploring Alkaline Stable Organic Cations for Polymer Hydroxide Exchange Membranes (United States)


    Reinholdt, J. Durand , Journal of Physical Chemistry C 2012, 116, 8510-8522. [151] C. Zhang, J. Hu, J. Cong, Y. Zhao, W. Shen, H. Toyoda, M. Nagatsu...Y. Iriyama, T. Abe, M. Matsuoka, K. Kikuchi, Z. Ogumi, Thin Solid Films 2008, 516, 3309-3313. 147 [155] M. Schieda, S. Roualdes, J. Durand , A

  18. Elucidating bonding preferences in tetrakis(imido)uranate(VI) dianions (United States)

    Anderson, Nickolas H.; Xie, Jing; Ray, Debmalya; Zeller, Matthias; Gagliardi, Laura; Bart, Suzanne C.


    Actinyl species, [AnO2]2+, are well-known derivatives of the f-block because of their natural occurrence and essential roles in the nuclear fuel cycle. Along with their nitrogen analogues, [An(NR)2]2+, actinyls are characterized by their two strong trans-An-element multiple bonds, a consequence of the inverse trans influence. We report that these robust bonds can be weakened significantly by increasing the number of multiple bonds to uranium, as demonstrated by a family of uranium(VI) dianions bearing four U-N multiple bonds, [M]2[U(NR)4] (M = Li, Na, K, Rb, Cs). Their geometry is dictated by cation coordination and sterics rather than by electronic factors. Multiple bond weakening by the addition of strong π donors has the potential for applications in the processing of high-valent actinyls, commonly found in environmental pollutants and spent nuclear fuels.

  19. Charge transfer dissociation (CTD) mass spectrometry of peptide cations using kiloelectronvolt helium cations. (United States)

    Hoffmann, William D; Jackson, Glen P


    A kiloelectronvolt beam of helium ions is used to ionize and fragment precursor peptide ions starting in the 1+ charge state. The electron affinity of helium cations (24.6 eV) exceeds the ionization potential of protonated peptides and can therefore be used to abstract an electron from--or charge exchange with--the isolated precursor ions. Kiloelectronvolt energies are used, (1) to overcome the Coulombic repulsion barrier between the cationic reactants, (2) to overcome ion-defocussing effects in the ion trap, and (3) to provide additional activation energy. Charge transfer dissociation (CTD) of the [M+H](+) precursor of Substance P gives product ions such as [M+H](2+•) and a dominant series of a ions in both the 1+ and 2+ charge states. These observations, along with the less-abundant a + 1 ions, are consistent with ultraviolet photodissociation (UVPD) results of others and indicate that C-C(α) cleavages are possible through charge exchange with helium ions. Although the efficiencies and timescale of CTD are not yet suitable for on-line chromatography, this new approach to ion activation provides an additional potential tool for the interrogation of gas phase ions.

  20. Quantum chemistry study of uranium(VI), neptunium(V), and plutonium(IV,VI) complexes with preorganized tetradentate phenanthrolineamide ligands. (United States)

    Xiao, Cheng-Liang; Wu, Qun-Yan; Wang, Cong-Zhi; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun


    The preorganized tetradentate 2,9-diamido-1,10-phenanthroline ligand with hard-soft donors combined in the same molecule has been found to possess high selectivity toward actinides in an acidic aqueous solution. In this work, density functional theory (DFT) coupled with the quasi-relativistic small-core pseudopotential method was used to investigate the structures, bonding nature, and thermodynamic behavior of uranium(VI), neptunium(V), and plutonium(IV,VI) with phenanthrolineamides. Theoretical optimization shows that Et-Tol-DAPhen and Et-Et-DAPhen ligands are both coordinated with actinides in a tetradentate chelating mode through two N donors of the phenanthroline moiety and two O donors of the amide moieties. It is found that [AnO2L(NO3)](n+) (An = U(VI), Np(V), Pu(VI); n = 0, 1) and PuL(NO3)4 are the main 1:1 complexes. With respect to 1:2 complexes, the reaction [Pu(H2O)9](4+)(aq) + 2L(org) + 2NO3(-)(aq) → [PuL2(NO3)2](2+)(org) + 9H2O(aq) might be another probable extraction mechanism for Pu(IV). From the viewpoint of energy, the phenanthrolineamides extract actinides in the order of Pu(IV) > U(VI) > Pu(VI) > Np(V), which agrees well with the experimental results. Additionally, all of the thermodynamic reactions are more energetically favorable for the Et-Tol-DAPhen ligand than the Et-Et-DAPhen ligand, indicating that substitution of one ethyl group with one tolyl group can enhance the complexation abilities toward actinide cations (anomalous aryl strengthening).

  1. Highly selective and efficient removal of arsenic(V), chromium(VI) and selenium(VI) oxyanions by layered double hydroxide intercalated with zwitterionic glycine. (United States)

    Asiabi, Hamid; Yamini, Yadollah; Shamsayei, Maryam


    In this study, a new strategy for highly selective and extremely efficient removal of toxic oxyanions (Cr(VI), Se(VI), and As(V)) from aqueous solutions using zwitterionic glycine intercalated layered double hydroxide (Gly-LDH) was reported. Hence, to investigate the effect of zwitterionic glycine on the adsorption capacity, selectivity factor and adsorption mechanism of LDHs, two NiAl LDHs intercalated with different inter-layer anions, including NO 3 - and glycine, were synthesized. The obtained results show that the adsorption capacity and selectivity factor of oxyanions through ion exchange mechanism in NO 3 -LDH is lower than Gly-LDH. Gly-LDH displayed a selectivity order of Se(VI)exceptionally rapid, showing a 93.5% removal within 30min, 98.0% removal within 40min, and ∼100% removal within 70min. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Diffusion characteristics of agarose hydrogel used in diffusive gradients in thin films for measurements of cations and anions. (United States)

    Wang, Yan; Ding, Shiming; Gong, Mengdan; Xu, Shiwei; Xu, Weimin; Zhang, Chaosheng


    The agarose hydrogel has been increasingly used as a diffusive layer in diffusive gradients in thin films (DGT) measurements. However its diffusive characteristics have not been examined in detail. In this study, the performance of agarose gel was tested in DGT measurements of eight cations (Fe(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), and Cd(II)) and eight anions (P(V), As(V), Cr(VI), Mo(VI), Sb(V), Se(VI), V(V), and W(VI)). It was found that the thickness of agarose, a key parameter in the calculation of DGT measured concentration, remained unchanged after hydration followed by storage under the following conditions: pH 2-11, ionic strength 0-1.0 M, temperature 4-40 °C, and with the storage time extending to 300 d. Enrichment of cations and repelling of anions were observed in the gel under the ionic strengths of cations and anions through the agarose gel (plus a PVDF filter membrane) were on average 1.10 ± 0.04 times of the reported diffusion coefficients through the agarose cross-linked polyacrylamide (APA) hydrogel, typically used in DGT technique. The working pH ranges for the agarose gel-assembled DGTs were 4-10 and 5-9 for anions and cations, respectively. The use of agarose gel, either individually or along with different filter membranes, affected the overall diffusion rates of cations and anions. The measured DGT concentrations of cations and anions in filtered natural freshwater and seawater were mostly in line with those measured directly. The results showed that the agarose gel can be used as one of the standard diffusive layers in DGT measurements for a wide range of inorganic and organic analytes. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Effect of Divalent Cations on RED Performance and Cation Exchange Membrane Selection to Enhance Power Densities

    NARCIS (Netherlands)

    Rijnaarts, Timon; Huerta, Elisa; van Baak, Willem; Nijmeijer, Kitty


    Reverse electrodialysis (RED) is a membrane-based renewable energy technology that can harvest energy from salinity gradients. The anticipated feed streams are natural river and seawater, both of which contain not only monovalent ions but also divalent ions. However, RED using feed streams

  4. Oxidative treatment of diclofenac via ferrate(VI) in aqueous media: effect of surfactant additives. (United States)

    Wang, Yingling; Ni, Tianjun; Yuan, Jianmei; Wang, Chunfeng; Liu, Guoguang


    The potential reaction of diclofenac (DCF) with ferrate(VI) and influences of coexisting surfactants have not been investigated in depth, and are the focus of this study. The results demonstrated that DCF reacted effectively and rapidly with Fe(VI) and approximately 75% of DCF (0.03 mM) was removed by excess Fe(VI) (0.45 mM) within 10 min. All of the reactions followed pseudo first-order kinetics with respect to DCF and Fe(VI), where the apparent second-order rate constant (kapp) was 5.07 M(-1) s(-1) at pH 9.0. Furthermore, the degradation efficiencies of DCF were clearly dependent on the concentrations of dissolved organic matter additives in the substrate solution. Primarily, inhibitory effects were observed with the samples that contained anionic (sodium dodecyl-benzene sulfonate, SDBS) or non-ionic (Tween-80) surfactants, which have been attributed to the side reactions between Fe(VI) and surfactants, which led to a reduction in the available oxidant for DCF destruction. Furthermore, the addition of a cationic surfactant (cetyltrimethyl ammonium bromide, CTAB) and humic acid (HA) conveyed significantly promotional effects on the DCF-Fe(VI) reaction. The rate enhancement effect for CTAB might be due to micellar surface catalysis, through the Coulomb attraction between the reactants and positively charged surfactants, while the catalytic action for HA resulted from the additional oxidation of Fe(V)/Fe(IV) in the presence of HA. The results provided the basic knowledge required to understand the environmental relevance of DCF oxidation via Fe(VI) in the presence of surfactant additives.

  5. Potassium Niobate Nanolamina: A Promising Adsorbent for Entrapment of Radioactive Cations from Water (United States)

    Sun, Jin; Yang, Dongjiang; Sun, Cuihua; Liu, Long; Yang, Shuanglei; (Alec) Jia, Yi; Cai, Rongsheng; Yao, Xiangdong


    Processing and managing radioactive waste is a great challenge worldwide as it is extremely difficult and costly; the radioactive species, cations or anions, leaked into the environment are a serious threat to the health of present and future generations. We report layered potassium niobate (K4Nb6O17) nanolamina as adsorbent to remove toxic Sr2+, Ba2+ and Cs+ cations from wastewater. The results show that K4Nb6O17 nanolamina can permanently confine the toxic cations within the interlayer spacing via a considerable deformation of the metastable layered structure during the ion exchange process. At the same time, the nanolaminar adsorbent exhibits prompt adsorption kinetics, high adsorption capacity and selectivity, and superior acid resistance. These merits make it be a promising material as ion exchanger for the removal of radioactive cations from wastewater.

  6. Har vi brug for hovedregning?

    DEFF Research Database (Denmark)

    Ejersbo, Lisser Rye


    Hvor ofte har vi brug for at regne noget i hoved? Har de fleste af os ikke altid et elektronisk hjælpemiddel ved hånden enten som en lille lommeregner eller telefonen? Selvom det umiddelbart kan synes unødvendigt at træne hovedregning, viser det sig, at netop træning af hovedregning støtter...... udvikling af hurtige regnestrategier, hvorfor det faktisk er en god ide at investere tid og energi i at træne netop dette....

  7. Cation-Anion Balance during Potassium and Sodium Absorption by Barley Roots (United States)

    Jackson, P. C.; Adams, H. R.


    Steady-state rates of potassium ion and sodium ion absorption by excised barley roots accompanied by various anions were compared with the rates of anion absorption and the concomitant H+ and base release by the roots. The cation absorption rates were found to be independent of the identities, concentrations, and rates of absorption of the anions of the external solution, including bicarbonate. Absorption of the anion of the salt plus bicarbonate could not account for the cation absorption. H+ is released during cation absorption and base during anion absorption. The magnitude by which one or the other predominates depends on the relative rates of anion and cation absorption under various conditions of pH, cation and anion concentration, and inhibitor concentrations. The conclusion is that potassium and sodium ions are absorbed independently of the anions of the absorption solution in exchange for H+, while anions are exchanged for a base. The H+ release reflects a specificity between K+ and Na+ absorption such that it appears to be H+ exchanged in the specific rate-limiting reactions of the cation absorption. PMID:13964256

  8. Vi tror ikke noget, vi undersøger det

    DEFF Research Database (Denmark)

    Hansen, Gitte Riis; Winther Johannsen, Inger


    I diskussionerne om, hvad der kan betegnes som god viden i forhold til udvikling af pædagogisk ud-vikling og kvalitet, er yderpunkterne kridtet op. Begreber som ”evidensbaseret” og ”datainformeret” synes at udfordre det pædagogiske felts egen forståelse af faglighed og pædagogisk kvalitet. I proj...... tager afsæt i det konkrete projekt og samarbejdet med døgntilbuddene. Vi viser, at arbejdet med datainformeret metode på denne måde ikke er en udradering af pædagogisk faglighed knyttet til fagprofessionel dømmekraft – snarere tværtimod...

  9. Extraction of a alkali metal cations using a lipophilic lariat ether having a c-pivot carboxylic acid sidearm

    Energy Technology Data Exchange (ETDEWEB)

    Sachleben, R.A.; Moyer, B.A.; Case, F.I.; Driver, J.L.


    The extraction of alkali metal cations by the lipophilic, ionizable lariat ether bis-tert-octylbenzo- 14-crown-4-acetic acid (BOB14C4AA) dissolved in either o-xylene or 1-octanol was studied by two-phase potentiometric titration and ion-exchange chromatography. BOB14C4AA extracts alkali metal cations from aqueous chloride solutions predominantly by ion exchange in the range p[H] > 7. From an aqueous mixture of alkali metal halides, BOB14C4AA extracts Li{sup +} cation preferentially up to complete loading. When the alkali metals are extracted individually, however, BOB14C4AA extracts Li{sup +} cation with highest efficiency only up to ca. 45% loading. Both selectivity and efficiency for extraction of Li{sup +} cation are enhanced with 1-octanol diluent as compared to o-xylene diluent.

  10. Mens vi venter på finansloven ..

    DEFF Research Database (Denmark)

    Madsen, Mogens Ove


    Vi må dog lufte en forsigtig optimisme over, at der kom signaler om opgør med detailstyring og knopskydningen af øremærket forskning.......Vi må dog lufte en forsigtig optimisme over, at der kom signaler om opgør med detailstyring og knopskydningen af øremærket forskning....

  11. Når vi taler om 68

    DEFF Research Database (Denmark)

    Jensen, Henrik; Metz, Georg

    Når vi taler om 68 er en intellektuel samtale mellem to ligeværdige gentlemen og skallesmækkere. En essayistisk dyst om porno, RAF, Pittelkow og livsfilosofi......Når vi taler om 68 er en intellektuel samtale mellem to ligeværdige gentlemen og skallesmækkere. En essayistisk dyst om porno, RAF, Pittelkow og livsfilosofi...


    National Research Council Canada - National Science Library

    Drake, Leigh


    The ViBe District in Virginia Beach is a hub for the local arts community. There is a fenced area in the ViBe District that features a whole row of murals created by professional artists, amateurs, and student groups from all over...


    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...

  14. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong


    The employment of metal salts is quite limited in asymmetric catalysis, although it would provide an additional arsenal of safe and inexpensive reagents to create molecular functions with high optical purity. Cation chelation by polyethers increases the salts' solubility in conventional organic...... 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...... 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...

  15. Econophys-Kolkata VI Conference

    CERN Document Server

    Chakrabarti, Bikas; Chakraborti, Anirban; Ghosh, Asim


    The primary goal of the book is to present the ideas and research findings of active researchers such as physicists, economists, mathematicians and financial engineers working in the field of “Econophysics,” who have undertaken the task of modeling and analyzing systemic risk, network dynamics and other topics. Of primary interest in these studies is the aspect of systemic risk, which has long been identified as a potential scenario in which financial institutions trigger a dangerous contagion mechanism, spreading from the financial economy to the real economy. This type of risk, long confined to the monetary market, has spread considerably in the recent past, culminating in the subprime crisis of 2008. As such, understanding and controlling systemic risk has become an extremely important societal and economic challenge. The Econophys-Kolkata VI conference proceedings are dedicated to addressing a number of key issues involved. Several leading researchers in these fields report on their recent work and al...

  16. Dissimilatory Reduction of Cr(VI), Fe(III), and U(VI) by Cellulomonas Isolates

    Energy Technology Data Exchange (ETDEWEB)

    Smith, William Aaron; Apel, William Arnold; Peyton, B. M.; Petersen, J. N.; Sani, R.


    The reduction of Cr(VI), Fe(III), and U(VI) was studied using three recently isolated environmental Cellulomonas sp. (WS01, WS18, and ES5) and a known Cellulomonas strain (Cellulomonas flavigena ATCC 482) under anaerobic, non-growth conditions. In all cases, these cultures were observed to reduce Cr(VI), Fe(III), and U(VI). In 100 h, with lactate as electron donor, the Cellulomonas isolates (500 mg/l total cell protein) reduced nitrilotriacetic acid chelated Fe(III) [Fe(III)-NTA] from 5 mM to less than 2.2 mM, Cr(VI) from 0.2 mM to less than 0.001 mM, and U(VI) from 0.2 mM to less than 0.12 mM. All Cellulomonas isolates also reduced Cr(VI), Fe(III), and U(VI) in the absence of lactate, while no metal reduction was observed in either the cell-free or heat-killed cell controls. This is the first report of Cellulomonas sp. reducing Fe(III) and U(VI). Further, this is the first report of Cellulomonas spp. coupling the oxidation of lactate, or other unknown electron donors in the absence of lactate, to the reduction of Cr(VI), Fe(III), and U(VI).

  17. Dissimilatory reduction of Cr(VI), Fe(III), and U(VI) by Cellulomonas isolates. (United States)

    Sani, R K; Peyton, B M; Smith, W A; Apel, W A; Petersen, J N


    The reduction of Cr(VI), Fe(III), and U(VI) was studied using three recently isolated environmental Cellulomonas sp. (WS01, WS18, and ES5) and a known Cellulomonas strain ( Cellulomonas flavigena ATCC 482) under anaerobic, non-growth conditions. In all cases, these cultures were observed to reduce Cr(VI), Fe(III), and U(VI). In 100 h, with lactate as electron donor, the Cellulomonas isolates (500 mg/l total cell protein) reduced nitrilotriacetic acid chelated Fe(III) [Fe(III)-NTA] from 5 mM to less than 2.2 mM, Cr(VI) from 0.2 mM to less than 0.001 mM, and U(VI) from 0.2 mM to less than 0.12 mM. All Cellulomonas isolates also reduced Cr(VI), Fe(III), and U(VI) in the absence of lactate, while no metal reduction was observed in either the cell-free or heat-killed cell controls. This is the first report of Cellulomonas sp. reducing Fe(III) and U(VI). Further, this is the first report of Cellulomonas spp. coupling the oxidation of lactate, or other unknown electron donors in the absence of lactate, to the reduction of Cr(VI), Fe(III), and U(VI).

  18. Genetics Home Reference: collagen VI-related myopathy (United States)

    ... Twitter Home Health Conditions Collagen VI-related myopathy Collagen VI-related myopathy Printable PDF Open All Close ... Javascript to view the expand/collapse boxes. Description Collagen VI-related myopathy is a group of disorders ...

  19. Finite difference simulation of biological chromium (VI) reduction in ...

    African Journals Online (AJOL)

    (VI) concentration profiles inside porous aquifer media columns. The model was thereafter used to calculate Cr(VI) removal rate for a range of Cr(VI) loadings. Internal concentration profiles were modelled against data collected from ...

  20. Incorporation of cationic electron donor of Ni-pyridyltetrathiafulvalene with anionic electron acceptor of polyoxometalate. (United States)

    Tsunashima, Ryo; Matsumoto, Takumi; Hoshino, Norihisa; Niiho, Wataru; Kimura, Mizuki; Kondo, Kei; Suyama, Yoshihiko; Nishioka, Yukihiro; Kawamata, Jun; Noro, Shin-ichiro; Nakamura, Takayoshi; Akutagawa, Tomoyuki; Ishiguro, Katsuya


    A new salt-[Ni(II)(DMSO)(5)(TTFPy)](2)[α-SiW(12)O(40)] (1)-based on polyoxometalates was prepared by coordinating a cationic electron donor of pyridyltetrathiafulvalene (TTFPy) with Ni(II). Although the TTFPy molecule did not form a salt with the anionic α-[SiW(VI)(12)O(40)](4-) because of the weak charge-transfer (CT) interaction, the coordination of Ni with the pyridyl moiety permitted salt formation driven by electrostatic interaction, giving a single crystal of 1. Crystallographic analysis, UV-vis and IR spectroscopy and electrochemical characterization revealed that the fully oxidized α-[SiW(VI)(12)O(40)](4-) was crystallized with the neutral TTFPy moiety from the acetonitrile solution because of the low electron-withdrawing ability of α-[SiW(VI)(12)O(40)](4-), forming a brown-orange crystal. The crystal colour quickly turned to black by immersing in methanol, due to CT from TTF moiety to α-[SiW(VI)(12)O(40)](4-), which was caused by the solvent effect. Increase in the solvent acceptor number from 18.9 for acetonitrile to 41.3 for methanol resulted in the enhancement of the electron withdrawing ability of α-[SiW(VI)(12)O(40)](4-) by 0.317 V in methanol.

  1. Natural zeolite reactivity towards ozone: the role of compensating cations. (United States)

    Valdés, Héctor; Alejandro, Serguei; Zaror, Claudio A


    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. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Pervaporation with ion exchange membranes

    Energy Technology Data Exchange (ETDEWEB)

    Boeddeker, K.W.; Wenzlaff, A.


    Sorption and pervaporation of aqueous-organic solvent systems (water-ethanol; water-carboxylic acids) with commercial ion exchange membranes are compared to obtain information on polymersolvent interaction vs. coupling. Close agreement between sorption selectivity and pervaporation selectivity indicates coupling. If pervaporation is less selective than sorption, polymer-solvent interaction overtakes coupling, the limit of de-coupling being phase separation within the sorbate as signaled by a sudden increase in permeability of the lesser interacting component. As long as sorption and pervaporation operate in parallel, favoring enrichment of the same component, coupling enhances the separation effect. If pervaporation counteracts sorption, coupling is detrimental to the separation effect. Potential applications include the dehydration of pre-concentrated water-ethanol using anion exchange membranes, and the enrichment of acetic acid from dilute aqueous solution by pervaporative removal of water through cation exchange membranes.

  3. Chemical Denudation and Cation Depletion in a Semi-Arid Catchment of the Long-Term Agroecological Research Observatory (United States)

    Shaljian, M.; Keller, C. K.; Jones, K. B.; Brooks, E. S.; Huggins, D. R.


    The Long-Term Agroecosystem Research (LTAR) network of the USDA is a nationwide observatory and decadal-timescale field-experimental study of sustainable food production. The LTAR thus supports investigation of hydroecological and biogeochemical processes that could affect agricultural sustainability over the course of the 21st century. Mineral-derived nutrient cations are essential to fertility, and acidification of soils due to chemical fertilization may result in unsustainable chemical denudation of the soil exchange pool. Mineral weathering also contributes to base cation denudation. This study investigated base cation losses for one year in drainage from a semi-arid, rain-fed catchment at the Cook Agronomy Farm (CAF) LTAR site in southeastern Washington. We measured flows, analyzed drainage samples and estimated hydrologic effluxes of base cations from the catchment. The total dissolved base cation denudation rate at CAF-LTAR is about 40 kg ha-1 yr-1, which is comparable to other catchments on silicate terranes. The 2.1keq ha-1 yr-1 of denuded cationic charge is dominated by Ca2+ (61%) and Mg2+ (35%). Principal counter-ions are HCO3- (43%), NO3- (38%) and SO42- (16%), suggesting that both H2CO3 and HNO3 are important acids. Comparing 2008 soil pH and base saturation at CAF-LTAR to a nearby native prairie site, we preliminarily estimate a loss of 120 keq ha-1 of base cations from the upper 1.5m of the soil exchangeable cation pool. Dividing this depletion by the estimated denudation flux returns 60 years, which is approximately the interval of chemically intensive agriculture here. This may suggest that the source of exported base cations in drainage is primarily cation exchange rather than mineral weathering. The LTAR observatory will support ongoing monitoring and experimentation necessary to better understand base cation depletion and how it interacts with agroecological changes over the next several decades.

  4. 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


    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.

  5. A computational study of anion-modulated cation-π interactions. (United States)

    Carrazana-García, Jorge A; Rodríguez-Otero, Jesús; Cabaleiro-Lago, Enrique M


    The interaction of anions with cation-π complexes formed by the guanidinium cation and benzene was thoroughly studied by means of computational methods. Potential energy surface scans were performed in order to evaluate the effect of the anion coming closer to the cation-π pair. Several structures of guanidinium-benzene complexes and anion approaching directions were examined. Supermolecule calculations were performed on ternary complexes formed by guanidinium, benzene, and one anion and the interaction energy was decomposed into its different two- and three-body contributions. The interaction energies were further dissected into their electrostatic, exchange, repulsion, polarization and dispersion contributions by means of local molecular orbital energy decomposition analysis. The results confirm that, besides the electrostatic cation-anion attraction, the effect of the anion over the cation-π interaction is mainly due to polarization and can be rationalized following the changes in the anion-π and the nonadditive (three-body) terms of the interaction. When the cation and the anion are on the same side of the π system, the three-body interaction is anticooperative, but when the anion and the cation are on opposite sides of the π system, the three-body interaction is cooperative. As far as we know, this is the first study where this kind of analysis is carried out with a structured cation as guanidinium with a significant biological interest.

  6. Cation affinity numbers of Lewis bases

    Directory of Open Access Journals (Sweden)

    Christoph Lindner


    Full Text Available Using selected theoretical methods the affinity of a large range of Lewis bases towards model cations has been quantified. The range of model cations includes the methyl cation as the smallest carbon-centered electrophile, the benzhydryl and trityl cations as models for electrophilic substrates encountered in Lewis base-catalyzed synthetic procedures, and the acetyl cation as a substrate model for acyl-transfer reactions. Affinities towards these cationic electrophiles are complemented by data for Lewis-base addition to Michael acceptors as prototypical neutral electrophiles.

  7. Comparision in the solvent extraction behavior of uranium (VI) in some trialkyl phosphates in ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Rama, R.; Rout, Alok; Venkatesan, K.A.; Antony, M.P.; Suresh, A. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Fuel Chemistry Division


    Higher homologs of trialkyl phosphates (TAlP) are proposed for reprocessing of fast reactor fuels. Solvent extraction behavior of U(VI) from nitric acid medium was studied in some TAlP present in 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C{sub 8}mim][NTf{sub 2}]) ionic liquid. The extractants investigated were tri-n-propylphosphate (TPP), tri-n-butylphosphate (TBP), tri-n-amylphosphate (TAP), tri-n-octylphosphate (TOP), tri-iso-amylphosphate (TIAP) and tri-iso-butylphosphate (TIBP). The extraction of uranium (VI) was investigated as a function of various parameters, such as the equilibration time, [HNO{sub 3}], [TAlP], temperature and nature of ionic liquid cation. The distribution ratios of U(VI) increased with an increase in the concentration of nitric acid and decreases in the order TOP>TAP≅ TIAP>TBP≅TIBP>TPP. The stoichiometry of the extraction was determined by slope analysis of the extraction data. Distribution ratios of U (VI) were determined at various temperatures and the thermodynamic parameters were derived. Quantitative stripping of uranium from the loaded ionic liquid phase was achieved using dilute nitric acid.

  8. 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.


    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.

  9. Emissions of chromium (VI) from arc welding. (United States)

    Heung, William; Yun, Myoung-Jin; Chang, Daniel P Y; Green, Peter G; Halm, Chris


    The presence of Cr in the +6 oxidation state (Cr[VI]) is still observed in ambient air samples in California despite steps taken to reduce emissions from plating operations. One known source of emission of Cr(VI) is welding, especially with high Cr-content materials, such as stainless steels. An experimental effort was undertaken to expand and update Cr(VI) emission factors by conducting tests on four types of arc-welding operations: gas-metal arc welding (GMAW), shielded metal arc welding (SMAW), fluxcore arc welding, and pulsed GMAW. Standard American Welding Society hood results were compared with a total enclosure method that permitted isokinetic sampling for particle size-cut measurement, as well as total collection of the aerosol. The fraction of Cr(VI) emitted per unit mass of Cr electrode consumed was determined. Consistent with AP-42 data, initial results indicate that a significant fraction of the total Cr in the aerosol is in the +6 oxidation state. The fraction of Cr(VI) and total aerosol mass produced by the different arc welding methods varies with the type of welding process used. Self-shielded electrodes that do not use a shield gas, for example, SMAW, produce greater amounts of Cr(VI) per unit mass of electrode consumed. The formation of Cr(VI) from standard electrode wires used for welding mild steel was below the method detection limit after eliminating an artifact in the analytical method used.

  10. Development of a stable cation modified graphene oxide membrane for water treatment (United States)

    Yu, Wenzheng; (Yet Yu, Tong; Graham, Nigel


    Membranes prepared from layers of graphene oxide (GO) offer substantial advantages over conventional materials for water treatment (e.g. greater flux), but the stability of GO membranes in water has not been achieved until now. In this study the behavior of GO membranes prepared with different quantities and species of cations has been investigated to establish the feasibility of their application in water treatment. A range of cation-modified GO membranes were prepared and exposed to aqueous solutions containing specific chemical constituents. In pure water, unmodified and Na-modified GO membranes were highly unstable, while GO membranes modified with multivalent cations were stable provided there were sufficient quantities of cations present; their relative capability to achieve GO stability was as follows: Al3+  >  Ca2+  >  Mg2+  >  Na+. It is believed that the mechanism of cross-linking, and membrane stability, is via metal-carboxylate chelates and cation-graphite surface interactions (cation-π interaction), and that the latter appears to increase with increasing cation valency. The instability of cation (Ca or Al)-modified GO membranes by NaCl solutions during permeation occurred as Na+ exchanged with the incorporated multivalent cations, but a high content of Al3+ in the GO membrane impeded Al3+/Na+ exchange and thus retained membrane stability. In solutions containing biopolymers representative of surface waters or seawater (protein and polysaccharide solutions), Ca-GO membranes (even with high Ca2+ content) were not stable, while Al-GO membranes were stable if the Al3+ content was sufficiently high; Al-formed membranes also had a greater flux than Ca-GO membranes.

  11. Anaerobic bio-removal of uranium (VI) and chromium (VI): Comparison of microbial community structure

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Monica [Centro de Ciencias do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Faleiro, Maria Leonor [IBB - Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Chaves, Sandra; Tenreiro, Rogerio [Universidade de Lisboa, Faculdade de Ciencias, Centro de Biodiversidade, Genomica Integrativa e Funcional (BioFIG), Campus de FCUL, Campo Grande 1749-016 Lisboa (Portugal); Santos, Erika [Centro de Ciencias do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Costa, Maria Clara, E-mail: [Centro de Ciencias do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)


    Several microbial communities, obtained from uranium contaminated and non-contaminated samples, were investigated for their ability to remove uranium (VI) and the cultures capable for this removal were further assessed on their efficiency for chromium (VI) removal. The highest efficiency for removal of both metals was observed on a consortium from a non-contaminated soil collected in Monchique thermal place, which was capable to remove 91% of 22 mg L{sup -1} U(VI) and 99% of 13 mg L{sup -1} Cr(VI). This study revealed that uranium (VI) removing communities have also ability to remove chromium (VI), but when uranium (VI) was replaced by chromium (VI) several differences in the structure of all bacterial communities were observed. TGGE and phylogenetic analysis of 16S rRNA gene showed that the uranium (VI) removing bacterial consortia are mainly composed by members of Rhodocyclaceae family and Clostridium genus. On the other hand, bacteria from Enterobacteriaceae family were detected in the community with ability for chromium (VI) removal. The existence of members of Enterobacteriaceae and Rhodocyclaceae families never reported as chromium or uranium removing bacteria, respectively, is also a relevant finding, encouraging the exploitation of microorganisms with new abilities that can be useful for bioremediation.

  12. Learning the vi and Vim Editor

    CERN Document Server

    Robbins, Arnold; Hannah, Elbert


    There's nothing that hard-core Unix and Linux users are more fanatical about than their text editor. Editors are the subject of adoration and worship, or of scorn and ridicule, depending upon whether the topic of discussion is your editor or someone else's. vi has been the standard editor for close to 30 years. Popular on Unix and Linux, it has a growing following on Windows systems, too. Most experienced system administrators cite vi as their tool of choice. And since 1986, this book has been the guide for vi. However, Unix systems are not what they were 30 years ago, and neither is this

  13. Mucopolissacaridose tipo VI: relato de caso


    Lais Orosco Bialon Santana; Carolina Ando Matsuno; Marta Wey Vieira


    Introdução: As mucopolissacaridoses são erros inatos do metabolismo de depósito lisossomal subclassificadas segundo a enzima deficiente. A arilsulfatase B (ARSB), responsável por degradar os glicosaminoglicanos (GAGs), que atuam no tecido conjuntivo, é deficiente na mucopolissacaridose tipo VI (MP VI). A MP VI tem clínica variável, sem anormalidades ao nascimento, evidenciando-se progressivamente ao acúmulo de GAGs. O diagnóstico se faz pela redução da atividade da ARSB ou da mutação genética...

  14. Cotton fiber/ZrO{sub 2}, a new material for adsorption of Cr(VI) ions in water

    Energy Technology Data Exchange (ETDEWEB)

    Muxel, Alfredo Alberto; Nobre Gimenez, Sonia Maria; Souza Almeida, Flaveli Aparecida de; Silva Alfaya, Reni Ventura da; Silva Alfaya, Antonio Alberto da [Departamento de Quimica, Universidade Estadual de Londrina-UEL, Londrina, PR (Brazil)


    The natural cotton fiber was used to synthesize an anion exchange, containing ZrO{sub 2} film on its surface, NCFZC (natural cotton fiber/ZrO{sub 2} composite). This anion exchanger was produced by the reaction of the zirconium oxychloride and hydroxyl groups on surface of the natural cotton fiber. The material was used for Cr(VI) ions adsorption studies. Adsorption equilibrium time and optimum pH for Cr(VI) adsorption were found to be 6 h and 4.0, respectively. The Langmuir and Temkin isotherms were used to models adsorption equilibrium data. The adsorption capacity of NCFZC was found to be 1.33 mmol/g. Kinetic studies showed that the rate of adsorption of Cr(VI) on NCFZC obeyed a pseudo-second-order kinetic model. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Tripodal receptors for cation and anion sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman, [Unknown; Verboom, Willem; Reinhoudt, David


    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

  16. Natural zeolite reactivity towards ozone: The role of compensating cations

    Energy Technology Data Exchange (ETDEWEB)

    Valdes, Hector, E-mail: [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)


    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.

  17. Efficient continuous removal of nitrates from water with cationic cellulose nanopaper membranes

    Directory of Open Access Journals (Sweden)

    Andreas Mautner


    Full Text Available Nitrates constitute a severe problem for the quality of potable water. The removal of nitrates from water can be performed utilizing continuously operating cellulose nanopaper ion-exchangers, which so far are unfortunately of only moderate efficiency. Here we demonstrate cationic cellulose nanopapers comprising cellulose nanofibrils carrying a high amount of ammonium groups (1.6 g mmol−1, i.e. 0.62 mmol g−1, which are anticipated to enable efficient removal of nitrate ions from aqueous solutions. Thin nanopapers were shown to have high adsorption capacities. Therefore we prepared low grammage nanopapers using a papermaking process from cellulose nanofibrils prepared from paper mill sludge. The performance of these cationic nanopapers was characterized by their permeance, with these new cationic nanopapers having a permeance of more than 100 L m−2 h−1 MPa−1, which is far greater than the permeance of conventional nanopapers. Furthermore, nitrate ions were successfully removed from water by capturing them through adsorption onto the cationic nanopaper by primarily an ion-exchange mechanism. These cationic nanopapers possessed adsorption capacities of almost 300 mg g−1, which is superior to commonly used nanopaper ion-exchangers and batch-wise applied adsorbents. Utilization of an industrial side-stream in combination with very good membrane performance demonstrates the use of resource efficient technologies in an important sector.

  18. Exchange Network (United States)

    The Environmental Information Exchange Network (EIEN) is an Internet-based system used by state, tribal and territorial partners to securely share environmental and health information with one another and EPA.

  19. Ion exchange properties of humus acids (United States)

    Shoba, V. N.; Chudnenko, K. V.


    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.

  20. Cationic electrodepositable coating composition comprising lignin (United States)

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter


    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  1. ViSIT: Visitor Survey Information Tool (United States)

    US Fish and Wildlife Service, Department of the Interior — ViSIT is an interactive web tool created by USGS to visualize the data collected as part of the National Wildlife Refuge Visitor Survey. The national survey was...

  2. Derfor elsker og hader vi positiv psykologi

    DEFF Research Database (Denmark)

    Mehlsen, Camilla


    Hvorfor er positiv psykologi så populært? Er positiv psykologi ved at blive en religion? Asterisk har mødt tre fremtrædende forskere, der forklarer, hvorfor vi elsker og hader positiv psykolog.......Hvorfor er positiv psykologi så populært? Er positiv psykologi ved at blive en religion? Asterisk har mødt tre fremtrædende forskere, der forklarer, hvorfor vi elsker og hader positiv psykolog....

  3. Kan vi forebygge en kompliceret sorgreaktion?

    DEFF Research Database (Denmark)

    Nielsen, Mette Kjærgaard; Guldin, Mai-Britt


    Pårørende til alvorligt syge patienter er i en sårbar situation og risikerer selv at blive syge. Som sundhedsprofessionelle har vi mulighed for at støtte pårørende i palliative forløb, og vi vil i denne artikel beskrive mulige prædiktorer for kompliceret sorg og depression hos den pårørende efter...

  4. Hvad skal vi med Trump-satire?

    DEFF Research Database (Denmark)

    Møller, Mette


    Trump-satire er et stort hit, og særligt en lang række satiriske videohilsner til Trump fra lande verden over får folk til at trække på smilebåndet. Men hvorfor er det så sjovt at gøre grin med Trump, og hvad kan vi bruge den politiske humor til? Link:

  5. SaVi: satellite constellation visualization


    Wood, Lloyd


    SaVi, a program for visualizing satellite orbits, movement, and coverage, is maintained at the University of Surrey. This tool has been used for research in academic papers, and by industry companies designing and intending to deploy satellite constellations. It has also proven useful for demonstrating aspects of satellite constellations and their geometry, coverage and movement for educational and teaching purposes. SaVi is introduced and described briefly here.

  6. Porous inorganic capsules in action: modelling transmembrane cation-transport parameter-dependence based on water as vehicle. (United States)

    Haupt, Erhard T K; Wontorra, Claudia; Rehder, Dieter; Müller, Achim


    Insight into basic principles of cation transport through "molecular channels", and especially details of the related fundamental H2O vehicle function, could be obtained via7Li NMR studies of the Li+ uptake/release processes by the unique porous nanocapsule [{(MoVI)MoVI5O21(H2O)6}12{MoV2O4(SO4)}30]72- which behaves as a semi-permeable inorganic membrane open for H2O and small cations; channel traffic as well as internal cavity distribution processes show a strong dependence on "environmental" effects such as exerted by solvent properties, the amount of water present, and competing complexing ligands, and end up in a complex equilibrium situation as in biological leak channels.

  7. Assessment of the effects of cadmium and lead on pH and cation ...

    African Journals Online (AJOL)

    The effects of heavy metals pollution on agricultural produce can not be over emphasize. To estimate the effect of heavy metal on pH and Cation Exchange Capacities of soil on incubation, relationships between availability of metals in soil after contamination were investigated for a range of soils and metals.

  8. VI International Workshop on Nature Inspired Cooperative Strategies for Optimization

    CERN Document Server

    Otero, Fernando; Masegosa, Antonio


    Biological and other natural processes have always been a source of inspiration for computer science and information technology. Many emerging problem solving techniques integrate advanced evolution and cooperation strategies, encompassing a range of spatio-temporal scales for visionary conceptualization of evolutionary computation. This book is a collection of research works presented in the VI International Workshop on Nature Inspired Cooperative Strategies for Optimization (NICSO) held in Canterbury, UK. Previous editions of NICSO were held in Granada, Spain (2006 & 2010), Acireale, Italy (2007), Tenerife, Spain (2008), and Cluj-Napoca, Romania (2011). NICSO 2013 and this book provides a place where state-of-the-art research, latest ideas and emerging areas of nature inspired cooperative strategies for problem solving are vigorously discussed and exchanged among the scientific community. The breadth and variety of articles in this book report on nature inspired methods and applications such as Swarm In...

  9. Incorporation of Monovalent Cations in Sulfate Green Rust

    DEFF Research Database (Denmark)

    Christiansen, B. C.; Dideriksen, K.; Katz, A.


    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...

  10. When Ligand Exchange Leads to Ion Exchange: Nanocrystal Facets Dictate the Outcome. (United States)

    Hewavitharana, Indika K; Brock, Stephanie L


    This study demonstrates that ligand exchange of nanocrystals (NCs) is not always an innocuous process, but can lead to facile (room temperature) ion exchange, depending on the surface crystal faceting. Rock salt PbTe NCs prepared as cubes with neutral facets undergo room-temperature ligand exchange with sulfide ions, whereas cuboctahedron-shaped particles with neutral {100} and polar {111} facets are transformed to PbS, driven by ion exchange along the ⟨111⟩ direction. Likewise, cation exchange (with Ag + ) occurs rapidly for cuboctahedra, whereas cubes remain inert. This dramatic difference is attributed to the relative surface area of {111} facets that promote rapid ion exchange and shows how facet engineering is a powerful knob for the control of reaction pathways in nanoparticles.

  11. Electrostatically driven resonance energy transfer in "cationic" biocompatible indium phosphide quantum dots. (United States)

    Devatha, Gayathri; Roy, Soumendu; Rao, Anish; Mallick, Abhik; Basu, Sudipta; Pillai, Pramod P


    Indium Phosphide Quantum Dots (InP QDs) have emerged as an alternative to toxic metal ion based QDs in nanobiotechnology. The ability to generate cationic surface charge, without compromising stability and biocompatibility, is essential in realizing the full potential of InP QDs in biological applications. We have addressed this challenge by developing a place exchange protocol for the preparation of cationic InP/ZnS QDs. The quaternary ammonium group provides the much required permanent positive charge and stability to InP/ZnS QDs in biofluids. The two important properties of QDs, namely bioimaging and light induced resonance energy transfer, are successfully demonstrated in cationic InP/ZnS QDs. The low cytotoxicity and stable photoluminescence of cationic InP/ZnS QDs inside cells make them ideal candidates as optical probes for cellular imaging. An efficient resonance energy transfer (E ∼ 60%) is observed, under physiological conditions, between the cationic InP/ZnS QD donor and anionic dye acceptor. A large bimolecular quenching constant along with a linear Stern-Volmer plot confirms the formation of a strong ground state complex between the cationic InP/ZnS QDs and the anionic dye. Control experiments prove the role of electrostatic attraction in driving the light induced interactions, which can rightfully form the basis for future nano-bio studies between cationic InP/ZnS QDs and anionic biomolecules.

  12. Hydrogen exchange

    DEFF Research Database (Denmark)

    Jensen, Pernille Foged; Rand, Kasper Dyrberg


    Hydrogen exchange (HX) monitored by mass spectrometry (MS) is a powerful analytical method for investigation of protein conformation and dynamics. HX-MS monitors isotopic exchange of hydrogen in protein backbone amides and thus serves as a sensitive method for probing protein conformation...... and dynamics along the entire protein backbone. This chapter describes the exchange of backbone amide hydrogen which is highly quenchable as it is strongly dependent on the pH and temperature. The HX rates of backbone amide hydrogen are sensitive and very useful probes of protein conformation......, as they are distributed along the polypeptide backbone and form the fundamental hydrogen-bonding networks of basic secondary structure. The effect of pressure on HX in unstructured polypeptides (poly-dl-lysine and oxidatively unfolded ribonuclease A) and native folded proteins (lysozyme and ribonuclease A) was evaluated...

  13. Spectrophotometric study of neptunium (VI) complexation by nitrate ions; Etude par spectrophotometrie de la complexation du neptunium au degre d'oxydation (VI) par les ions nitrates

    Energy Technology Data Exchange (ETDEWEB)

    Pochon, P. [CEA/VALRHO - site de Marcoule, Dept. de Recherche en Retraitement et en Vitrification (DRRV), 30 - Marcoule (France)]|[Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France)]|[Centre Regional Associe de Lyon, 69 (France)


    Neptunium(VI) complexation by nitrate ions was investigated by visible and near-infrared spectrophotometry, a technique suitable for observing the appearance and evolution of the species in solution. In the absence of reference spectra for Np(VI) nitrate- complexes, mathematical (factor analysis) tools were used to interpret the spectra. These chemo-metric techniques were first tested and validated on a simpler chemical system: Np(VI)complexation by the SiW{sub 11}O{sub 39}{sup 8-} anion. The test media used to investigate Np(VI) nitrate- complexes generally contain nitrate and perchlorate salts at high concentrations (high ionic strength). Media effects arising from the presence of cations, acidity or the perchlorate ion concentration are therefore significant, and no doubt account for the scattered values of the complexation constants published in the literature. The evolution of the neptunium spectra according to the parameters of the reaction medium illustrated these effects and allowed them to be quantified by a global 'perturbation constant'. In order to minimize the spectrum modifications due to media effects, the neptunium nitrate-complexes were studied at constant ionic strength in weak acidic media (2{sup -1}{sub H2O}) in the presence of sodium salts. The bulk formation constants and the spectrum of the NpO{sub 2}(NO{sub 3}){sup +} complex were determined for ionic strength values of 2.2, 4, 6 and 8{sup -1}{sub H2O}. The constants remained on the same order of magnitude regardless of the ionic strength; the thermodynamic constant {beta}{sub 1}{sup 0} determined from them according to specific interaction theory is thus probably of little significance. Conversely, the bulk constants can be corrected for the effects of the perchlorate ions by taking the global 'perturbation constant' into account. (author)

  14. Novel analysis of cation solvation using a graph theoretic approach. (United States)

    Mooney, Barbara Logan; Corrales, L Rene; Clark, Aurora E


    A new method for analyzing molecular dynamics simulation data is employed to study the solvent shell structure and exchange processes of mono-, di-, and trivalent metal cations in water. The instantaneous coordination environment is characterized in terms of the coordinating waters' H-bonding network, orientations, mean residence times, and the polyhedral configuration. The graph-theory-based algorithm provides a rapid frame-by-frame identification of polyhedra and reveals fluctuations in the solvation shell shape--previously unexplored dynamic behavior that in many cases can be associated with the exchange reactions of water between the first and second solvation shells. Extended solvation structure is also analyzed graphically, revealing details of the hydrogen bonding network that have practical implications for connecting molecular dynamics data to ab initio cluster calculations. Although the individual analyses of water orientation, residence time, etc., are commonplace in the literature, their combination with graphical algorithms is new and provides added chemical insight.

  15. Preparation of graphene oxide-manganese dioxide for highly efficient adsorption and separation of Th(IV)/U(VI). (United States)

    Pan, Ning; Li, Long; Ding, Jie; Li, Shengke; Wang, Ruibing; Jin, Yongdong; Wang, Xiangke; Xia, Chuanqin


    Manganese dioxide decorated graphene oxide (GOM) was prepared via fixation of crystallographic MnO2 (α, γ) on the surface of graphene oxide (GO) and was explored as an adsorbent material for simultaneous removal of thorium/uranium ions from aqueous solutions. In single component systems (Th(IV) or U(VI)), the α-GOM2 (the weight ratio of GO/α-MnO2 of 2) exhibited higher maximum adsorption capacities toward both Th(IV) (497.5mg/g) and U(VI) (185.2 mg/g) than those of GO. In the binary component system (Th(IV)/U(VI)), the saturated adsorption capacity of Th(IV) (408.8 mg/g)/U(VI) (66.8 mg/g) on α-GOM2 was also higher than those on GO. Based on the analysis of various data, it was proposed that the adsorption process may involve four types of molecular interactions including coordination, electrostatic interaction, cation-pi interaction, and Lewis acid-base interaction between Th(IV)/U(VI) and α-GOM2. Finally, the Th(IV)/U(VI) ions on α-GOM2 can be separated by a two-stage desorption process with Na2CO3/EDTA. Those results displayed that the α-GOM2 may be utilized as an potential adsorbent for removing and separating Th(IV)/U(VI) ions from aqueous solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Endomembrane Cation Transporters and Membrane Trafficking

    Energy Technology Data Exchange (ETDEWEB)

    Sze, Heven [Univ. of Maryland, College Park, MD (United States). Dept. of Cell Biology & Molecular Genetics


    Multicellular, as well as unicellular, organisms have evolved mechanisms to regulate ion and pH homeostasis in response to developmental cues and to a changing environment. The working hypothesis is that the balance of fluxes mediated by diverse transporters at the plasma membrane and in subcellular organelles determines ionic cellular distribution, which is critical for maintenance of membrane potential, pH control, osmolality, transport of nutrients, and protein activity. An emerging theme in plant cell biology is that cells respond and adapt to diverse cues through changes of the dynamic endomembrane system. Yet we know very little about the transporters that might influence the operation of the secretory system in plants. Here we focus on transporters that influence alkali cation and pH homeostasis, mainly in the endomembrane/ secretory system. The endomembrane system of eukaryote cells serves several major functions: i) sort cargo (e.g. enzymes, transporters or receptors) to specific destinations, ii) modulate the protein and lipid composition of membrane domains through remodeling, and iii) determine and alter the properties of the cell wall through synthesis and remodeling. We had uncovered a novel family of predicted cation/H+ exchangers (CHX) and K+ efflux antiporters (KEA) that are prevalent in higher plants, but rare in metazoans. We combined phylogenetic and transcriptomic analyses with molecular genetic, cell biological and biochemical studies, and have published the first reports on functions of plant CHXs and KEAs. CHX studied to date act at the endomembrane system where their actions are distinct from the better-studied NHX (Na/K-H+ exchangers). Arabidopsis thaliana CHX20 in guard cells modulate stomatal opening, and thus is significant for vegetative survival. Other CHXs ensure reproductive success on dry land, as they participate in organizing pollen walls, targeting of pollen tubes to the ovule or promoting

  17. Applying zeta potential measurements to characterize the adsorption on montmorillonite of organic cations as monomers, micelles, or polymers. (United States)

    Zadaka, Dikla; Radian, Adi; Mishael, Yael G


    A systematic study was carried out to characterize the adsorption of organic cations as monomers, micelles, or polymers on montmorillonite by monitoring zeta potential (ξ) as a function of cation loading on the clay. In general, the clay's ξ became less negative as cation loading increased. A fairly good linear correlation between adsorption of organic cations on the clay, up to the cation exchange capacity (CEC) of the clay, and ξ potential of the composites was fitted. However, when the adsorption of the larger cation exceeded the CEC, a nonlinear increase in ξ was measured. The degree of this increase corresponds to the cation size and affinity to the clay (in the order surfactantcations, ξ reached zero at polycation loadings that were significantly lower than the CEC. The zeta-adsorption plot of the polycations reached a well-defined plateau which correlates to the zeta potential of the polycations. The effect of electrolytes on ξ of the crude clay was monitored, and as expected, the extent of the effect increased with valency (Na(+)cation radius (Na(+)

  18. Treatment tests for ex situ removal of chromate, nitrate, and uranium (VI) from Hanford (100-HR-3) groundwater. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Beck, M.A.; Duncan, J.B.


    This report describes batch and anion exchange column laboratory-scale studies investigating ex situ methods to remove chromate (chromium [VI]), nitrate (NO{sub 3}), and uranium (present as uranyl (uranium [VI]) carbonato anionic species) from contaminated Hanford Site groundwaters. The technologies investigated include chemical precipitation or coprecipitation to remove chromate and uranium, and anion exchange to remove chromate, uranium, and nitrate. The technologies investigated were specified in the 100-HR-3 Groundwater Treatability Test Plan (DOE-RL 1993). The goal of these tests was to determine the best method to remove selected contaminants to below the concentration of the project performance goals. The raw data and observations made during these tests can be found in the Westinghouse Hanford Company (WHC) laboratory notebooks (Beck 1992, Herting 1993). The method recommended for future study is anion exchange with Dowex 21K resin.

  19. ARM Airborne Carbon Measurements VI (ACME VI) Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Biraud, S [Lawrence Berkeley National Laboratory


    From October 1 through September 30, 2016, the Atmospheric Radiation Measurement (ARM) Aerial Facility will deploy the Cessna 206 aircraft over the Southern Great Plains (SGP) site, collecting observations of trace-gas mixing ratios over the ARM’s SGP facility. The aircraft payload includes two Atmospheric Observing Systems, Inc., analyzers for continuous measurements of CO2 and a 12-flask sampler for analysis of carbon cycle gases (CO2, CO, CH4, N2O, 13CO2, 14CO2, carbonyl sulfide, and trace hydrocarbon species, including ethane). The aircraft payload also includes instrumentation for solar/infrared radiation measurements. This research is supported by the U.S. Department of Energy’s ARM Climate Research Facility and Terrestrial Ecosystem Science Program and builds upon previous ARM Airborne Carbon Measurements (ARM-ACME) missions. The goal of these measurements is to improve understanding of 1) the carbon exchange at the SGP site, 2) how CO2 and associated water and energy fluxes influence radiative forcing, convective processes and CO2 concentrations over the SGP site, and 3) how greenhouse gases are transported on continental scales.

  20. Exchange Options

    NARCIS (Netherlands)

    Jamshidian, F.


    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

  1. Separation of 1,3-Propanediol from Aqueous Solutions by Ion Exchange Chromatography

    National Research Council Canada - National Science Library

    Beata Rukowicz; Ireneusz Miesiąc; Krzysztof Alejski


    .... The separation of this product from fermentation broth is a difficult task. In this work, the application of cation exchange resin for the separation of 1,3-propanediol from model aqueous solution was examined...

  2. The Free Tricoordinated Silyl Cation Problem

    Directory of Open Access Journals (Sweden)

    Čičak, H.


    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.

  3. Afrikaans Syllabification Patterns


    Tilla Fick; Chris J. Swanepoel


    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 b...

  4. Metal cation/anion adsorption on calcium carbonate: Implications to metal ion concentrations in groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, J.M.; Cowan, C.E.; Resch, C.T.


    This chapter evaluates the sorption behavior of metallic ions on specimen calcite as a basis for determining the importance of calcite relative to other subsurface sorbents, such as layer silicates and oxides, in controlling metal ion concentration in calcareous groundwaters. A review of the literature shows the sorption of both metallic cations and anions on calcite over ranges in pH and CO{sub 2} partial pressure to be consistent with a surface-exchange process where cations exchange with surface Ca and anions exchange with surface CO{sub 3}. A general surface-exchange model was developed to account for the effects of Ca and CO{sub 3} concentrations, pH, and calcite surface area on cation and anion sorption onto calcite. The model was applied to recently developed experimental sorption data of Zn and SeO{sub 3} on specimen calcite in equilibrium CaCO{sub 3}(aq) suspensions. The surface-exchange model was able to describe the effects of pH on both cation and anion sorption, and provided good predictions of the effects of variable CO{sub 2}(g) pressure on Zn sorption and of PO{sub 4} on SeO{sub 3} sorption. The surface-exchange model, combined with sorption constants for other phases, was used to calculate Cd sorption to a hypothetical aquifer material containing a mixture of sorbents. The sorbent concentrations were fixed to those expected in groundwater zones. The multi-sorbent calculation documented the importance of calcite as a sorbent for metallic ions in groundwater.93 refs., 18 figs., 5 tabs.

  5. Adsorption mechanisms of metal cations from water on an oxidized carbon surface. (United States)

    Moreno-Castilla, C; Álvarez-Merino, M A; Pastrana-Martínez, L M; López-Ramón, M V


    Adsorption of Cr(III), Mn(II), Cu(II) and Zn(II) on an oxidized activated carbon cloth was studied. Its surface chemistry was characterized by potentiometric titration. This technique revealed the amount of surface oxygen functionalities and their acidity constant distribution. The acidity constant range involved in the metal cation adsorption was obtained from this distribution. Metal cation adsorption increased with higher adsorption temperature due to the increase in the negative surface charge of the oxidized activated carbon. Adsorption was by proton exchange and the number, amount and strength of the surface acid groups involved could be obtained. The proton exchange was by an inner-sphere or outer-sphere surface metal complex formation mechanism. In the case of divalent cation adsorption, the increase in temperature changed the adsorption mechanism from outer-sphere to inner-sphere. However, the adsorption mechanism of Cr(III) was outer-sphere and independent of temperature. Adsorption capacity augmented with the increase in the charge-to-size ratio of the hexa-aquo cations. In addition, the adsorption capacity of divalent cations increased with the rise in stability of the surface metal complex formed. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. Long-term effects of high nitrogen loads on cation and carbon riverine export in agricultural catchments. (United States)

    Aquilina, Luc; Poszwa, Anne; Walter, Christian; Vergnaud, Virginie; Pierson-Wickmann, Anne-Catherine; Ruiz, Laurent


    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.

  7. Anion stripping as a general method to create cationic porous framework with mobile anions. (United States)

    Mao, Chengyu; Kudla, Ryan A; Zuo, Fan; Zhao, Xiang; Mueller, Leonard J; Bu, Xianhui; Feng, Pingyun


    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.

  8. A theoretical study of ternary indole-cation-anion complexes. (United States)

    Carrazana-García, Jorge A; Cabaleiro-Lago, Enrique M; Campo-Cacharrón, Alba; Rodríguez-Otero, Jesús


    The simultaneous interactions of an anion and a cation with a π system were investigated by MP2 and M06-2X theoretical calculations. Indole was chosen as a model π system for its relevance in biological environments. Two different orientations of the anion, interacting with the N-H and with the C-H groups of indole, were considered. The four cations (Na(+), NH4(+), C(NH2)3(+) and N(CH3)4(+)) and the four anions (Cl(-), NO3(-), HCOO(-) and BF4(-)) included in the study are of biological interest. The total interaction energy of the ternary complexes was calculated and separated into its two- and three-body components and all of them are further divided into their electrostatic, exchange, repulsion, polarization and dispersion contributions using the local molecular orbital-energy decomposition analysis (LMO-EDA) methodology. The binding energy of the indole-cation-anion complexes depends on both ions, with the cation having the strongest effect. The intense cation-anion attraction determines the geometric and energetic features in all ternary complexes. These structures, with both ions on the same side of the π system, show an anti-cooperative interaction. However, the interaction is not only determined by electrostatics, but also the polarization contribution is important. Specific interactions like the one established between the anion and the N-H group of indole or the proton transfer between an acidic cation and a basic anion play a significant role in the energetics and the structure of particular complexes. The presence of the polar solvent as modelled with the polarizable continuum model (PCM) does not seem to have a significant effect on the geometry of the ternary complexes, but drastically weakens the interaction energy. Also, the strength of the interaction is reduced at a faster rate when the anion is pushed away, compared to the results obtained in the gas phase. The combination of PCM with the addition of one water molecule indicates that the PCM

  9. Vi overser hjertepatienter med ondt i livet

    DEFF Research Database (Denmark)

    Ørsted-Rasmussen, Morten; Pedersen, Susanne S.; Zwisler, Ann Dorthe Olsen


    Sundhedsvæsenet har ved en målrettet indsats sikret markant øget overlevelse efter blodprop i hjertet. Men vi risikerer at skylle det hele ud med badevandet, hvis der ikke bliver taget hånd om de psykiske følger i den kroniske fase af sygdommen......Sundhedsvæsenet har ved en målrettet indsats sikret markant øget overlevelse efter blodprop i hjertet. Men vi risikerer at skylle det hele ud med badevandet, hvis der ikke bliver taget hånd om de psykiske følger i den kroniske fase af sygdommen...

  10. Removal of Cr(VI) by surfactant modified Auricularia auricula spent substrate: biosorption condition and mechanism. (United States)

    Dong, Liying; Jin, Yu; Song, Tao; Liang, Jinsong; Bai, Xin; Yu, Sumei; Teng, Chunying; Wang, Xin; Qu, Juanjuan; Huang, Xiaomei


    Auricularia auricula spent substrate (AASS) modified by didodecyldimethylammonium bromide(DDAB) was used as adsorbent to remove Cr(VI) from aqueous solution. Based on a single-factor experiment and response surface methodology, the optimal conditions were adsorbent dosage of 1.5 g/L, pH value of 4.0, initial Cr(VI) concentration of 19 mg/L, temperature of 25 °C, biosorption time of 120 min, rotational speed of 150 r/min, respectively, under which biosorption capacity could reach 12.16 mg/g compared with unmodified AASS (6.058 mg/g). DDAB modification could enlarge the specific surface area and porous diameter of the adsorbents, and supply hydrophilic and hydrophobic groups capable of adsorbing at the interfaces. In addition, DDAB increased ionic exchange and complex formation demonstrated by variations of elemental contents, shifts of carboxyl, amine groups, hydroxyl, alkyl chains, and phosphate groups as well as the crystal structure of the Cr-O compounds. Variations of peaks and energy in XPS analysis also testified the reduction of Cr(VI) to Cr(III).The biosorption behavior of modified AASS was in line with Langmuir and Freundlich isotherm equation. The final regeneration efficiency was 62.33% after three biosorption-desorption cycles. Apparently, DDBA is a eximious modifier and DDBA-modified AASS was very efficient for Cr(VI) removal.

  11. Two anionic metal-organic frameworks with tunable luminescent properties induced by cations

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shu-Mei, E-mail: [College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chen, Yan-Fei; Liu, Liyang [College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108 (China); Wen, Tian, E-mail: [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Zhang, Hua-Bin; Zhang, Jian [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)


    Two three-dimensional (3-D) MOFs, [(C{sub 2}H{sub 5}){sub 4}N)]{sub 3}[H{sub 3}O]{sub 2}[Cd{sub 6}Br(H{sub 2}-DHBDC){sub 8}(DMF){sub 4}] (1; H{sub 4}-DHBDC=2,5-dihydroxy-1,4-benzenedicarboxylic acid, DMF=N,N-dimethylformamide) and [(CH{sub 3}){sub 2}NH{sub 2}]{sub 2}[Cd{sub 3}(H2-DHBDC){sub 4}(DMF){sub 2}]·2DMF(2), are prepared from the self-assembly reactions between Cd(CH{sub 3}COO){sub 2} and H{sub 4}-DHBDC, respectively. Both anionic frameworks consist of linear trinuclear Cd units (e.g., 1: [Cd{sub 3}BrO{sub 2}(CO{sub 2}){sub 7}] and [Cd{sub 3}O{sub 2}(CO{sub 2}){sub 8}]; 2: [Cd{sub 3}O{sub 2}(CO{sub 2}){sub 8}]) linked by the H{sub 2}-DHBDC ligands. The photoluminescent properties of compound 1 are tunable through cation-exchange with different metal ions. The results demonstrated an effective ion-exchange approach toward the functional modification of MOF materials. - Graphical abstract: Two organic cations induced three-dimensional anionic Cd(II) metal-organic frameworks were synthesized under solvothermal conditions, which showed interesting tunable photoluminescent emissions due to organic cations exchange. - Highlights: • Organic cations induced anionic Cd(II) MOFs. • Cations exchange. • Tunable photoluminescent emissions.

  12. Two polyoxometallate-based supramolecular compounds influenced by the ratio between the polyoxometallate anion and organic cation. (United States)

    Zhang, Qian; Liu, Jie; Lu, Jing; Gong, Shu-Wen


    Two polyoxometallate-based compounds, tris[1,1'-(butane-1,4-diyl)bis(1H-imidazol-3-ium)] bis[tetracosa-μ2-oxido-dodecaoxido-μ12-phosphato-dodecamolybdenum(VI)], (C10H16N4)3[PMo12O40]2, (I), and 1,1'-(butane-1,4-diyl)bis(1H-imidazol-3-ium) 1-[4-(1H-imidazol-1-yl)butyl]-1H-imidazol-3-ium tetracosa-μ2-oxido-dodecaoxido-μ12-phosphato-dodecamolybdenum(VI) dihydrate, (C10H16N4)(C10H15N4)[PMo12O40]·2H2O, (II), were synthesized by hydrothermal techniques at different pH values. The stoichiometric ratio between the polyoxometallate (POM) anions and organic cations is 2:3 in (I), with one of the cations lying on an inversion centre. The doubly protonated 1,1'-(butane-1,4-diyl)diimidazole (BIM) cations are linked to the [PMo12O40](3-) anions by hydrogen bonds to form a three-dimensional supramolecular network. The stoichiometric ratio of POM anions and organic cations is 1:2 in (II), and the anion is located about a centre of inversion. The partly protonated BIM cations and solvent water molecules form hydrogen bonds with the [PMo12O40](3-) anions, yielding a two-dimensional supramolecular layer. The different lattice architectures of (I) and (II) may be governed by the ratio between the POM anions and organic cations, which, in turn, is determined by the pH value.

  13. Cation-π interactions in competition with cation microhydration: a theoretical study of alkali metal cation-pyrene complexes. (United States)

    Pašalić, Hasan; Aquino, Adelia J A; Tunega, Daniel; Haberhauer, Georg; Gerzabek, Martin H; Lischka, Hans


    Cation-π interactions were systematically investigated for the adsorption of H(+) and alkali metal cations M(+) to pyrene by means of Møller-Plesset perturbation theory (MP2) and density functional theory (DFT). The main aims were to determine the preferred adsorption sites and how the microhydration shell influences the adsorption process. The preferred adsorption sites were characterized in terms of structural parameters and energetic stability. Stability analysis of the M(+)-pyrene complexes revealed that the binding strength and the barrier to transitions between neighboring sites generally decreased with increasing cation size from Li(+) to Cs(+). Such transitions were practically barrierless (cations, respectively. While the isolated complexes possessed only one minimum, two minima-corresponding to an inner and an outer complex-were observed for microhydrated complexes. The small Li(+) ion formed a stable hydration shell and preferentially interacted with water rather than pyrene. In contrast, K(+) favored cation-π over cation-water interactions. It was found that the mechanism for complex formation depends on the balance between cation-π interactions, cation-water complexation, and the hydrogen bonding of water to the π-system.

  14. Afrikaans Syllabification Patterns

    Directory of Open Access Journals (Sweden)

    Tilla Fick


    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


    African Journals Online (AJOL)



    May 20, 2016 ... water and air. It affects the growth of flora and fauna which in turn affect human health negatively. Chromium could also bio-accumulate in plants and animals and this becomes ... The sorption kinetic models of Cr (VI) onto the biosorbents were examined with ... bulk density, moisture and ash contents.

  16. 76 FR 60593 - Title VI; Proposed Circular (United States)


    ... for FTA staff to make oral presentations about the two proposed Circulars and allow attendees an... proposed Circular would incorporate lessons learned from triennial reviews, discretionary Title VI... Implementation Plan for Limited English Proficient (LEP) persons now contains a summary of the DOT LEP guidance...

  17. Prospek pengembangan industri perkulitan pada pelita VI


    D. Karyadi


    The leather industry is one of the strong competitive industry, as it comes from renewable natural resources. Therefore, the leather industry has good prospect to develop at the Pelita VI to be the industrial products export competitive. To develop leather industry and leather products should be given closed attention and well managed, especially concerning raw material supply, quality and leather waste treatment.

  18. Resúmenes Presentaciones Orales VI ECAP


    Vargas Arana, Editor Gabriel


    En este artículo se pueden encontrar los resúmenes de las presentaciones orales del VI Ecuentro Científico de la Amazonía Peruana, desarrollado el 27 y 28 de cotubre de 2015 en la ciudad de Iquitos, Perú.

  19. Vi har selv designet naturens love

    DEFF Research Database (Denmark)

    Bentzen, Martin Mose


    ForskerZonenNaturlovene er universelt gyldige i de flestes øjne. De gælder altid, uanset hvad vi tænker. Men dette billede står ikke uimodsagt i videnskabsfilosofien, og der er meget, der tyder på, at det ikke er specielt empirisk korrekt...

  20. Chromium(VI) bioremediation by probiotics. (United States)

    Younan, Soraia; Sakita, Gabriel Z; Albuquerque, Talita R; Keller, Rogéria; Bremer-Neto, Hermann


    Chromium is a common mineral in the earth's crust and can be released into the environment from anthropogenic sources. Intake of hexavalent chromium (Cr(VI)) through drinking water and food causes toxic effects, leading to serious diseases, and is a commonly reported environmental problem. Microorganisms can mitigate or prevent the toxic effects caused by heavy metals in addition to having effective resistance mechanisms to prevent cell damage and bind to these metals, sequestering them from the cell surface and removing them from the body. Species of Lactobacillus, Streptococcus, Bacillus and Bifidobacterium present in the human mouth and gut and in fermented foods have the ability to bind and detoxify some of these substances. This review address the primary topics related to Cr(VI) poisoning in animals and humans and the use of probiotics as a way to mitigate or prevent the toxic effects caused by Cr(VI). Further advances in the genetic knowledge of such microorganisms may lead to discoveries which will clarify the most active microorganisms that act as bioprotectants in bodies exposed to Cr(VI) and are an affordable option for people and animals intoxicated by the oral route. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  1. 77 FR 52116 - Title VI; Final Circular (United States)


    ... enforcement of Title VI disparate impact regulations, it did not undermine the validity of those regulations... streamlined this process. We have modified the definition of ``disparate impact'' for clarity. We decline to... process reengineering. In response, FTA will review the public engagement plan and its implementation when...

  2. Hvem er vi? Hvem er de?

    DEFF Research Database (Denmark)

    Kryger, Niels


    Kommentaren tager afsæt i initiativer i de pædagogiske faglige foreninger i Europa EERA) og i Norden (NERA) og argumenterer for at det er forpligtelse for os som nordiske og europæiske pædagogiske forskere at gå op imod de stadigt mere ekskluderende vi-konstruktioner, som er blevet formuleret i for...

  3. U(VI) extraction by 8-hydroxyquinoline. A comparison study in ionic liquid and in dichloromethane

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Li-Yong; Shi, Wei-Qun [Chinese Academy of Sciences, Beijing (China). Lab. of Nuclear Energy Chemistry; Liao, Xiang-Hong [Chinese Academy of Sciences, Beijing (China). Lab. of Nuclear Energy Chemistry; East China Institute of Technology, Nanchang (China). School of Nuclear Engineering and Geophysics; Liu, Zhi-Rong [East China Institute of Technology, Nanchang (China). School of Nuclear Engineering and Geophysics; Chai, Zhi-Fang [Chinese Academy of Sciences, Beijing (China). Lab. of Nuclear Energy Chemistry; Soochow Univ., Suzhou (China). School of Radiological and Interdisciplinary Sciences and Collaborative Innovation Center of Radiation Medicine


    Room temperature ionic liquids (RTILs) represent a recent new class of solvents with potential application in liquid/liquid extraction based nuclear fuel reprocessing due to their unique physical and chemical properties. The work herein provides a comparison of U(VI) extraction by 8-hydroxyquinoline (HOX) in a commonly used RTIL, i.e. 1-butyl-3-methylimidazolium hexafluorophosphate ([C{sub 4}mim][PF{sub 6}]) and in conventional solvent, i.e. dichloromethane (CH{sub 2}Cl{sub 2}). The effect of HOX concentration, solution acidity and nitrate ions on the extraction were discussed in detail, and the speciation analyses of the extracted U(VI) were performed. One of the main emphasis of this work is the extraction mechanism of U(VI) extracted from aqueous phase into RTILs and conventional solvent. In CH{sub 2}Cl{sub 2}, the extraction occurs through a combination of ion change and neutral complexation, and the extracted complex is proposed as UO{sub 2}(OX){sub 2}HOX. In [C{sub 4}mim][PF{sub 6}], although a cation-change mechanism as previously reported for RTILs-based system was involved, the extracted complex of UO{sub 2}(OX){sub 1.5}(HOX){sub 1.5}(PF6){sub 0.5} gave a clear indication that the usage of HOX as an acidic extractant markedly inhibited the solubility loss of [C{sub 4}mim][PF{sub 6}] during the extraction by leaching H{sup +} to aqueous phase. Moreover, the extracted U(VI) in [C{sub 4}mim][PF{sub 6}] can be easily stripped by using 0.01 M nitric acid, which provides a simple way of the ionic liquid recycling.

  4. Optimization of divalent cation in Saccharomyces pastorianus ...

    African Journals Online (AJOL)

    Cassava starch fermentations were conducted in batch cultures to optimize the effect of divalent cations on ethanol production with Saccharomyces pastorianus using the central composite rotatable response surface design. Divalent cations used were magnesium (Mg2+), zinc (Zn2+) and calcium (Ca2+). Maximum ethanol ...

  5. Tripodal Receptors for Cation and Anion Sensors

    Directory of Open Access Journals (Sweden)

    David N. Reinhoudt


    Full Text Available 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 are emphasised, along with their potential applications in optical sensors or optodes.

  6. Cloning and expression of a Vi mimotope of Salmonella enterica ...

    African Journals Online (AJOL)



    Sep 15, 2009 ... A recombinant His-Vi protein of Salmonella enterica serovar Typhi was successfully constructed and cloned into an expression vector ... recombinant protein can be used to detect specific anti-Vi antibody produced by typhoid patients. Overall, the His-Vi ... E-mail: Tel.:603-. 79676607.

  7. Bioreduction of Cr (VI) by potent novel chromate resistant alkaliphilic ...

    African Journals Online (AJOL)

    Isolation of Cr (VI) resistant alkaliphilic bacteria from sediment and water samples collected from Wadi Natrun hypersaline Soda lakes (located in northern Egypt), resulted in isolation of several alkaliphilic bacterial strains that can tolerate up to 2.94 g/l of Cr (VI) in alkaline medium. However, with increasing Cr (VI) ...

  8. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.


    Polypyrrole (PPy) polymer films permanently doped with large, immobile anion dodecyl benzene sulfonate (DBS) have been characterized by cyclic voltammetry in order to clarify the roles of cations and anions in the aqueous electrolyte as mobile ions in the film. Aqueous solutions of 0.05-0.1 M...... and the expulsion of anions; a broad anodic peak centered at ca. - 0.5 V representing the expulsion of cations; and a second broad peak at +0.2 to +0.5 V corresponding to anions being inserted. Although the motion of cations is the most important, as expected, there is a significant anion contribution, thereby...... complicating reproducibility when employing PPy(DBS) polymers as actuators. When the cation is doubly charged, it enters the film less readily, and anions dominate the mobility. Using a large and bulky cation switches the mechanism to apparently total anion motion. The changes in area of the three peaks...

  9. Micelle mediated extraction and simultaneous spectrophotometric determination of vanadium(V) and molybdenum(VI) in plant foodstuff samples. (United States)

    Madrakian, Tayyebeh; Afkhami, Abbas; Siri, Reza; Mohammadnejad, Masoumeh


    A micelle-mediated extraction method for preconcentration of trace quantities of V(V) and Mo(VI) as a prior step to their simultaneous spectrophotometric determination has been developed. Bromopyrogallol red, cetyltrimethylammonium bromide (CTAB) (cationic surfactant) and KI were used as chelating, extraction and co-extraction agents, respectively. Mean centering (MC) of ratio spectra has been used for the simultaneous analysis of these metal ions. The optimal reaction and extraction conditions were optimised and the analytical characteristics of the method (e.g., limit of detection, linear range, maximum preconcentration and improvement factor) were obtained. Linearity was obeyed in the range 3.0-50.0ngmL(-1) for V(V) and Mo(VI). The detection limit of the method was 0.5 and 1.0ngmL(-1) for V(V) and Mo(VI), respectively. The method was applied to the simultaneous determination of V(V) and Mo(VI) in several plant foodstuff samples successfully. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Intracellular trafficking mechanism of cationic phospholipids including cationic liposomes in HeLa cells. (United States)

    Un, K; Sakai-Kato, K; Goda, Y


    The development of gene delivery methods is essential for the achievement of effective gene therapy. Elucidation of the intracellular transfer mechanism for cationic carriers is in progress, but there are few reports regarding the intracellular trafficking processes of the cationic phospholipids taken up into cells. In the present work, the trafficking processes of a cationic phospholipid (1,2-dioleoyl-3-trimethylammonium-propane, DOTAP) were investigated from intracellular uptake to extracellular efflux using cationic liposomes in vitro. Following intracellular transport of liposomes via endocytosis, DOTAP was localized in the endoplasmic reticulum, Golgi apparatus, and mitochondria. Moreover, the proteins involved in DOTAP intracellular trafficking and extracellular efflux were identified. In addition, helper lipids of cationic liposomes were found to partially affect this intracellulartrafficking. These findings might provide valuable information for designing cationic carriers and avoiding unexpected toxic side effects derived from cationic liposomal components.


    Long, R.S.; Bailes, R.H.


    A process for the recovery of certain metallic ions from aqueous solutions by ion exchange techniques is described. It is applicable to elements such as vanadium, chromium, nnanganese, and the like, which are capable of forming lower valent cations soluble in aqueous solutions and which also form ldgher valent anions soluble in aqueous acidic solutions. For example, small amounts of vanadium occurring in phosphoric acid prepared from phosphate rock may be recovered by reducing the vanadium to a trivalent cation adsorbing; the vanadium in a cationic exchange resin, then treating the resin with a suitable oxidizing agent to convert the adsorbed vanadium to a higher valent state, and finally eluting; the vanadium as an anion from the resin by means of an aqueous acidic solution.

  12. Protein phylogenetic analysis of Ca2+/cation antiporters and insights into their evolution in plants

    Directory of Open Access Journals (Sweden)

    Laura eEmery


    Full Text Available Cation transport is a critical process in all organisms and is essential for mineral nutrition, ion stress tolerance, and signal transduction. Transporters that are members of the Ca2+/Cation Antiporter (CaCA superfamily are involved in the transport of Ca2+ and/or other cations using the counter exchange of another ion such as H+ or Na+. The CaCA superfamily has been previously divided into five transporter families: the YRBG, NCX, NCKX, CAX and CCX families, which include the well-characterized Na+/Ca2+ exchanger (NCX and H+/cation exchanger (CAX transporters. To examine the evolution of CaCA transporters within higher plants and the green plant lineage, CaCA genes were identified from the genomes of sequenced flowering plants, a bryophyte, lycophyte, and freshwater and marine algae, and compared with those from non-plant species. We found evidence of the expansion and increased diversity of flowering plant genes within the CAX and CCX families. Genes related to the NCX family are present in land plant though they encode distinct MHX homologs which probably have an altered transport function. In contrast, the NCX and NCKX genes which are absent in land plants have been retained in many species of algae, especially the marine algae, indicating that these organisms may share ‘animal-like’ characteristics of Ca2+ homeostasis and signaling. A group of genes encoding novel CAX-like proteins containing an EF hand domain were identified from plants and selected algae but appeared to be lacking in any other species. Lack of functional data for most of the CaCA proteins make it impossible to reliably predict substrate specificity and function for many of the groups or individual proteins. The abundance and diversity of CaCA genes throughout all branches of life indicates the importance of this class of cation transporter, and that many transporters with novel functions are waiting to be discovered.


    This article, the second in a series, focuses on the results of bench- and pilot-scale studies of ion exchange processes for radium removal from groundwater in Lemont, Ill. Batch and column studies indicated a very high resin selectivity for radium compared with common cations. E...

  14. Cationic Bolaamphiphiles for Gene Delivery (United States)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad


    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  15. Influence of hydrogen cations on kinetics and equilibria of heavy-metal sorption by algae-sorption of copper cations by the algaPalmaria palmata(Linnaeus) Weber & Mohr (Rhodophyta). (United States)

    Kłos, Andrzej; Rajfur, Małgorzata


    The influence of hydrogen cations on kinetics and equilibria of sorption of copper cations by the marine alga Palmaria palmata (Linnaeus) Weber & Mohr was studied under static conditions. The competitive effect of the H + cations is described, which influenced the uncertainty of evaluation of the alga sorption capacity. Under static conditions, the variation of the Cu 2+ /H + concentration ratio during sorption was found nonmonotonic. The Langmuir isotherm model was used to determine the sorption capacity of the alga, namely 12.4 mg g -1 of dry algae mass. A similar value was determined from the kinetic parameters of the ionic exchange which is considered a pseudo-second-order chemical reaction. The consistent results indicated that the mathematical models used correctly described the equilibria and kinetics of the ionic exchange between algae and solutions.


    Energy Technology Data Exchange (ETDEWEB)

    Bunge, A.L.; Klein, G.; Radke, C.J.


    Exchange of hardness ions is important in enhanced oil recovery with chemical additives. In both micellar-polymer and caustic flooding processes, multivalent ions released from rock surfaces can interact with anionic surfactants, rendering them preferentially oil soluble and/or insoluble in water. Because hardness cations are sparingly soluble and precipitate in alkaline solutions, such solutions may be more efficient as surfactant flood preflushes than are softened brines. Multivalent ion precipitation may also occur in alkaline waterflooding. To permit design of such processes, this paper presents a chromatographic theory for simultaneous ion exchange with precipitation of divalent ions. Theoretical effluent histories and concentration profiles are presented for the cases of finite pulses and continuous injection of hydroxide ions into linear cores. Complete capture of the insoluble salt particles is assumed. Results are given for the case of instantaneous equilibration of the solution with the precipitate, as well for the case of complete nonequilibrium, in which the solid precipitate does not redissolve. The efficiency of alklaine preflushing is shown to depend on the exchange isotherm, initial divalent loading of the rock, injected pH and salinity, the solubility product of the precipitated salt, and pulse size. The effect of slug size on complete equilibrium removal of hardness ions is reduced efficiency with increasing size until a critical volume approximating continuous injection is reached. Increasing injected pH and salinity provides a more favorable response. Experimental data for Berea sandstone and an argillaceous sand compare favorably with the proposed theory.

  17. Segmented heat exchanger (United States)

    Baldwin, Darryl Dean; Willi, Martin Leo; Fiveland, Scott Byron; Timmons, Kristine Ann


    A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

  18. Noget vi kan tro på

    DEFF Research Database (Denmark)

    Olsen, Jan Brødslev


    Situationen er alvorlig. Verden står over for enorme udfordringer med pres på naturressourcer, klima, befolkningsvækst, flygtninge og konflikter. Det er svært at se, hvordan disse problemer kan håndteres inden for den nuværende menneskelige bevidstheds rammer. Vi må derfor foretage et bevidstheds......Situationen er alvorlig. Verden står over for enorme udfordringer med pres på naturressourcer, klima, befolkningsvækst, flygtninge og konflikter. Det er svært at se, hvordan disse problemer kan håndteres inden for den nuværende menneskelige bevidstheds rammer. Vi må derfor foretage et...

  19. Hvad skal vi med Trump-satire?

    DEFF Research Database (Denmark)

    Møller, Mette


    Trump-satire er et stort hit, og særligt en lang række satiriske videohilsner til Trump fra lande verden over får folk til at trække på smilebåndet. Men hvorfor er det så sjovt at gøre grin med Trump, og hvad kan vi bruge den politiske humor til?......Trump-satire er et stort hit, og særligt en lang række satiriske videohilsner til Trump fra lande verden over får folk til at trække på smilebåndet. Men hvorfor er det så sjovt at gøre grin med Trump, og hvad kan vi bruge den politiske humor til?...

  20. Alkali metal cation doped Al-SBA-15 for carbon dioxide adsorption. (United States)

    Zukal, Arnošt; Mayerová, Jana; Čejka, Jiří


    Mesoporous aluminosilicate adsorbents for carbon dioxide were prepared by the grafting of aluminium into SBA-15 silica using an aqueous solution of aluminium chlorohydrate. As the ion exchange sites are primarily associated with the presence of tetrahedrally coordinated aluminium, extra-framework aluminium on the SBA-15 surface was inserted into the silica matrix by a treatment with an aqueous solution of NH(4)OH. Synthesized mesoporous aluminosilicate preserving all the characteristic features of a mesoporous molecular sieve was finally modified by the alkali metal cation exchange. To examine carbon dioxide adsorption on prepared materials, adsorption isotherms in the temperature range from 0 °C to 60 °C were measured. Based on the known temperature dependence of adsorption isotherms, isosteric adsorption heats giving information on the surface energetics of CO(2) adsorption were calculated and discussed. The comparison of carbon dioxide isotherms obtained on aluminosilicate SBA-15, aluminosilicate SBA-15 containing cations Na(+) and K(+) and activated alumina F-200 reveals that the doping with sodium or potassium cations dramatically enhances adsorption in the region of equilibrium pressures lower than 10 kPa. Therefore, synthesized aluminosilicate adsorbents doped with Na(+) or K(+) cations are suitable for carbon dioxide separation from dilute gas mixtures. This journal is © the Owner Societies 2010