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Sample records for cation exchange capacity

  1. A comparison between three methods for the determination of cation exchange capacity and exchangeable cations in soils

    OpenAIRE

    Ciesielski, H.; Sterckeman, T.

    1997-01-01

    The object of this study is to compare the results obtained with three standardized methods of determination of cationic exchange capacity (CEC) and exchangeable cations (Ca, Mg, K) in soils. The three methods are based on different exchange reagents: cobalt hexamine (Cohex) trichloride, barium chloride and ammonium acetate. Exchange procedures are different as well; they are, respectively, single extraction, successive extractions and percolation. Values measured with barium and Cohex as ind...

  2. Black Carbon Increases Cation Exchange Capacity in Soils

    International Nuclear Information System (INIS)

    Black Carbon (BC) may significantly affect nutrient retention and play a key role in a wide range of biogeochemical processes in soils, especially for nutrient cycling. Anthrosols from the Brazilian Amazon (ages between 600 and 8700 yr BP) with high contents of biomass-derived BC had greater potential cation exchange capacity (CEC measured at pH 7) per unit organic C than adjacent soils with low BC contents. Synchrotron-based near edge X-ray absorption fine structure (NEXAFS) spectroscopy coupled with scanning transmission X-ray microscopy (STXM) techniques explained the source of the higher surface charge of BC compared with non-BC by mapping cross-sectional areas of BC particles with diameters of 10 to 50 (micro)m for C forms. The largest cross-sectional areas consisted of highly aromatic or only slightly oxidized organic C most likely originating from the BC itself with a characteristic peak at 286.1 eV, which could not be found in humic substance extracts, bacteria or fungi. Oxidation significantly increased from the core of BC particles to their surfaces as shown by the ratio of carboxyl-C/aromatic-C. Spotted and non-continuous distribution patterns of highly oxidized C functional groups with distinctly different chemical signatures on BC particle surfaces (peak shift at 286.1 eV to a higher energy of 286.7 eV) indicated that non-BC may be adsorbed on the surfaces of BC particles creating highly oxidized surface. As a consequence of both oxidation of the BC particles themselves and adsorption of organic matter to BC surfaces, the charge density (potential CEC per unit surface area) was greater in BC-rich Anthrosols than adjacent soils. Additionally, a high specific surface area was attributable to the presence of BC, which may contribute to the high CEC found in soils that are rich in BC

  3. Method for in situ determination cation exchange capacities of subsurface formations

    International Nuclear Information System (INIS)

    A method is disclosed for the in situ examination of each subsurface formation penetrated by a borehole to ascertain the cation exchange capacity of such formations within a geological region. Natural γ ray logging is used to develop signals functionally related to the total γ radiation and to the potassium-40, uranium and thorium energy-band radiations. A first borehole is traversed by a potential γ ray spectrometer to provide selected measurements of natural γ radiation. Core samples are taken from the logged formation and laboratory tests performed to determine the cation exchange capacity thereof. The cation exchange capacities thus are developed then correlated with selected parameters provided by the γ ray spectrometer to establish functional relationships. Cation exchange capacities of formations in subsequent boreholes within the region are then determined in situ by use of the natural γ ray spectrometer and these established relationships. (author)

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

    Directory of Open Access Journals (Sweden)

    Shadia M. Sirry

    2014-09-01

    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.

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

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  6. Preliminary studies of the total cation exchange capacity of sediments from two North Atlantic study sites

    International Nuclear Information System (INIS)

    Initially four different methods of measuring total cation exchange capacity were compared. There were two chemical methods (ammonium saturation with displacement into seawater, and barium saturation followed by replacement with magnesium) and two radiochemical methods (sodium-22 and caesium-134 saturation). The barium-magnesium and sodium-22 methods were then applied to sediment samples from Core D10164Pound1K from the Nares Fracture Valley, and Core D10554Pound11K from the eastern flank of the Great Meteor Rise. The material at site 10164 is a pelagic clay whereas at site 10554 it is carbonate ooze. The total cation exchange capacities (T.C.E.C.) of samples from the two sites are similar when measured by the sodium-22 method, the mean for Core 10164 was 21.7 meq/100g and 24.4 meq/100g for Core 10554. However for Core 10554 the barium-magnesium method gives a mean of 42.8 meq/100g. The difference in T.C.E.C. measured by the two methods appears to be due to the high calcite content of core 10554 sediment. Measured exchange capacities are lower than in coastal sediments. In deep sea sediments organic matter either makes a very small contribution to the T.C.E.C. (core 10164) or actually blocks exchange sites (Core 10554). Amorphous oxides of iron and manganese contribute between 20 and 50% of the T.C.E.C. (author)

  7. Preparation and characterization of high capacity, strong cation-exchange fiber based adsorbents.

    Science.gov (United States)

    Schwellenbach, Jan; Taft, Florian; Villain, Louis; Strube, Jochen

    2016-05-20

    Motivated by the demand for more economical capture and polishing steps in downstream processing of protein therapeutics, a novel strong cation-exchange chromatography stationary phase based on polyethylene terephthalate (PET) high surface area short-cut fibers is presented. The fiber surface is modified by grafting glycidyl methacrylate (GMA) via surface-initiated atom transfer radical polymerization (SI-ATRP) and a subsequent derivatization leading to sulfonic acid groups. The obtained cation-exchange fibers have been characterized and compared to commercially available resin and membrane based adsorbers. High volumetric static binding capacities for lysozyme (90mg/mL) and polyclonal human IgG (hIgG, 92mg/mL) were found, suggesting an efficient multi-layer binding within the grafted hydrogel layer. A packed bed of randomly orientated fibers has been tested for packing efficiency, permeability and chromatographic performance. High dynamic binding capacities for lysozyme (50mg/mL) and hIgG (54mg/mL) were found nearly independent of the bed-residence time, revealing a fast mass-transport mechanism. Height equivalent to a theoretical plate (HETP) values in the order of 0.1 cm and a peak asymmetry factor (AF) of 1.8 have been determined by tracer experiments. Additionally inverse size-exclusion chromatography (iSEC) revealed a bimodal structure within the fiber bed, consisting of larger transport channels, formed by the voidage between the fibers, and a hydrogel layer with porous properties. PMID:27106396

  8. Obtention of the cation exchange capacity of a natural kaolinite with radioactive tracers

    International Nuclear Information System (INIS)

    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 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)

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

    Institute of Scientific and Technical Information of China (English)

    XING Ting-xian

    2003-01-01

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

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

    International Nuclear Information System (INIS)

    The Chinese natural zeolite, in which clinoptilolite coexists with quartz was treated hydrothermally with NaOH solutions, either with or without fusion with NaOH powder as pretreatment. Zeolite Na-P, Na-Y and analcime were identified as the reacted products, depending on the reaction conditions such as NaOH concentration, reaction time and hydrothermal temperature. The products were identified by X-ray diffraction, and characterized by Fourier transform IR and ICP. With hydrothermal treatment after fusion of natural zeolite with NaOH, high purity of zeolite Na-Y and Na-P can be selectively formed, their cation exchange capacity (CEC) are 275 and 355 meq/100 g respectively, which are greatly higher than that of the natural zeolite (97 meq/100 g). Furthermore, the ammonium removal by the synthetic zeolite Na-P in aqueous solution was also studied. The equilibrium isotherms have been got and the influence of other cations present in water upon the ammonia uptake suggested an order of preference Ca2+ > K+ > Mg2+.

  11. Adsorption of reovirus to clay minerals: effects of cation-exchange capacity, cation saturation, and surface area.

    OpenAIRE

    Lipson, S M; Stotzky, G

    1983-01-01

    The adsorption of reovirus to clay minerals has been reported by several investigators, but the mechanisms defining this association have been studied only minimally. The purpose of this investigation was to elucidate the mechanisms involved with this interaction. More reovirus type 3 was adsorbed, in both distilled and synthetic estuarine water, by low concentrations of montmorillonite than by comparable concentrations of kaolinite containing a mixed complement of cations on the exchange com...

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

    Directory of Open Access Journals (Sweden)

    José Torrent

    2015-12-01

    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.

  13. Effect of efficient microorganisms on cation exchange capacity in acacia seedlings (Acacia melanoxylon) for soil recovery in Mondonedo, Cundinamarca

    International Nuclear Information System (INIS)

    We determined the effect of efficient microorganisms (EM) on the cation exchange capacity for soil recovery in the municipality of Mondonedo, Cundinamarca. A greenhouse unit was installed in order to maintain stable conditions. After harvesting, sifted and homogenization of the soil sample, initial physical and chemical analyses were made. For the experimental units we used Acacia melanoxylon seedlings from Zabrinsky. A completely randomized design was done with eight treatments and three repetitions. For the maintenance and monitoring of the seedlings behaviour, a frequency of irrigation of three times per week was found. The application of the EM was done during three months: in the first month, it was applied four times (once a week); during the second month, it was applied twice (biweekly), and during the third month there was only one application. Additionally, every 15 days morphological analyses were made (number of leaves, branches and stem diameter). In the end, soil samples were taken from each plant pot. In the laboratory we analysed the cation exchange capacity, alkali ion exchange, saturation alkali, relations between elements and plant tissue. These were done using an atomic absorption spectrophotometer. Statistical analyses consisted on multiple comparisons test and variance tests, in order to find whether or not treatments exhibited significant differences. In that way, the best alternative for improving environmental quality of eroded soils as the Zabrinsky desert is the efficient microorganisms in 5% doses in irrigation water. Additionally, the cation exchange capacity must be enhanced using organic fertilizers (compost, mulch and gallinaza) in one pound doses, and chemical fertilizers: electrolytic Mn (0.0002 g), Cu (0.0002 g), Zn (0.0001 g), URFOS 44 (166.66 g) and klip-boro (5 g).

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

    Science.gov (United States)

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

    2015-04-01

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

  15. Test procedure for cation exchange chromatography

    International Nuclear Information System (INIS)

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction

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

    Science.gov (United States)

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

    2015-10-01

    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.

  17. Estimation of soil cation exchange capacity using Genetic Expression Programming (GEP) and Multivariate Adaptive Regression Splines (MARS)

    Science.gov (United States)

    Emamgolizadeh, S.; Bateni, S. M.; Shahsavani, D.; Ashrafi, T.; Ghorbani, H.

    2015-10-01

    The soil cation exchange capacity (CEC) is one of the main soil chemical properties, which is required in various fields such as environmental and agricultural engineering as well as soil science. In situ measurement of CEC is time consuming and costly. Hence, numerous studies have used traditional regression-based techniques to estimate CEC from more easily measurable soil parameters (e.g., soil texture, organic matter (OM), and pH). However, these models may not be able to adequately capture the complex and highly nonlinear relationship between CEC and its influential soil variables. In this study, Genetic Expression Programming (GEP) and Multivariate Adaptive Regression Splines (MARS) were employed to estimate CEC from more readily measurable soil physical and chemical variables (e.g., OM, clay, and pH) by developing functional relations. The GEP- and MARS-based functional relations were tested at two field sites in Iran. Results showed that GEP and MARS can provide reliable estimates of CEC. Also, it was found that the MARS model (with root-mean-square-error (RMSE) of 0.318 Cmol+ kg-1 and correlation coefficient (R2) of 0.864) generated slightly better results than the GEP model (with RMSE of 0.270 Cmol+ kg-1 and R2 of 0.807). The performance of GEP and MARS models was compared with two existing approaches, namely artificial neural network (ANN) and multiple linear regression (MLR). The comparison indicated that MARS and GEP outperformed the MLP model, but they did not perform as good as ANN. Finally, a sensitivity analysis was conducted to determine the most and the least influential variables affecting CEC. It was found that OM and pH have the most and least significant effect on CEC, respectively.

  18. Changes of mineralogical-chemical composition, cation exchange capacity, and phosphate immobilization capacity during the hydrothermal conversion process of coal fly ash into zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Deyi Wu; Yanming Sui; Xuechu Chen; Shengbing He; Xinze Wang; Hainan Kong [Shanghai Jiao Tong University, Shanghai (China). School of Environmental Science and Engineering

    2008-08-15

    In the search for a technique to augment the nutrient removal capacity of zeolite synthesized from fly ash (ZFA), the present study investigated the changes of mineralogical-chemical composition, cation exchange capacity (CEC), and phosphate immobilization capacity (PIC) during the synthesis process. The ZFAs were obtained as a function of temperature (40-120{sup o}C), liquid/solid ratio (1-18 ml/g), NaOH concentration (0.5-4 mol/L) and reaction time (2-72 h). The formation of low-silica zeolites (P1, hydroxysodalite, and chabazite) and the stability of mullite were observed, causing a marked decrease in SiO{sub 2} content but roughly no change in Al{sub 2}O{sub 3} content during the synthesis process. The decrease in K{sub 2}O, MgO content and the insignificant change in Fe{sub 2}O{sub 3} and TiO{sub 2} content were related to the solubility of the oxides while the increase in Na{sub 2}O and CaO was due to the increase in CEC. A high CEC was achieved under a high temperature, a high liquid/solid ratio, a long reaction time, and an appropriate NaOH concentration (2 mol/L), while a maximum PIC was achieved under relatively mild synthesis conditions instead (e.g., a reasonably short reaction time 10 h). This discrepancy was explained by the fact that different controlling factors/components in ZFA are responsible for CEC (content and kind of zeolite) and PIC (Ca component, specific surface area, and dissociated Fe{sub 2}O{sub 3} and Al{sub 2}O{sub 3}). 20 refs., 4 figs., 2 tabs.

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

    OpenAIRE

    Mosayeb Heshmati; Arifin Abdu; Shamshuddin Jusop; Nik M. Majid

    2011-01-01

    Problem statement: Land use practice leads to changes in the physico-chemical properties of soils, such as Soil Organic Carbon (SOC), Cation Exchange Capacity (CEC) and Soil Aggregate Stability (SAS) that cause soil erosion. Approach: Merek catchment, Iran suffers from land degradation due to poor land use practice. A study was carried out with the objectives: (i) to determine soil nutrient status in different agro-ecological zones in Merek catchment; and (ii) to evaluate the influence of lan...

  20. Ion exchange behaviour of polymeric zirconium cations

    International Nuclear Information System (INIS)

    Polymeric zirconium cations formed in weakly acid solutions (pH2) are taken up strongly into macroporous cation exchange resins, while uptake into normal cation exchange resins (pore diameter about 1 nm) is low. Macroporous cation exchange resins loaded with polymeric Zr cations are shown to function as ligand exchange sorbents. (Authors)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-07-01

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

  2. Organometallic cation-exchanged phyllosilicates

    OpenAIRE

    Fleming, Shay

    1991-01-01

    Organotin (IV) complexes formed between 0 01 M dimethyltin dichloride solutions prepared at pH 2 6 and 4 0, and trimethyltin chloride prepared at pH 3 4, with Na- 119 montmori 1lonite clay have been characterised using Sn Mflssbauer spectroscopy, X-ray diffraction, thermogravimetric analysis and water sorption isotherms Following cation exchange, Mttssbauer spectroscopy identified two tin species in the dimethyltin (IV)-exchanged clay prepared at pH 2 6 A cis specie...

  3. Cation-Exchange Equilibria with Fused Salts

    International Nuclear Information System (INIS)

    Solute distributions of alkali metal, alkaline- earth, transition metal, and actinide ions have been studied in fused salt-cation exchanger systems. The fused salts employed were alkali halides and nitrates. The cation exchangers used were natural zeolites, synthetic zeolites, high-porosity glasses, and molten oxide mixtures. The molten exchangers were composed of Na2O and B2O3 in various proportions. The relative quantities not only determined the exchanger capacity and electrolyte penetration but also produced distribution coefficients for a given solute which varied over several orders of magnitude. Moreover, they produced marked reversals in the selectivity series. Additional studies on the anion distributions, miscibility diagrams, vapour pressures and diffusion rates in these systems have elucidated the mechanisms involved and the relation of selectivity to solute properties, system thermodynamics, exchanger structure and available functional groups. In the region of high Na2O composition, the distribution coefficients for mono-, di- and trivalent cations in NaCl have not only the same order of selectivity found in Dowex 50-HCl systems but also similar values for the distribution coefficients. The results are summarized qualitatively and compared to behaviour in aqueous systems (Table VII). (author)

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

    Directory of Open Access Journals (Sweden)

    F. da Costa Verdade

    1956-01-01

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

  5. [Effects of biochar amendment on cropland soil bulk density, cation exchange capacity, and particulate organic matter content in the North China Plain].

    Science.gov (United States)

    Chen, Hong-Xia; Du, Zhang-Liu; Guo, Wei; Zhang, Qing-Zhong

    2011-11-01

    A 3-year field experiment with randomized block design was conducted to study the effects of biochar amendment on the soil bulk density, cation exchange capacity (CEC), and particulate organic matter C (POM-C) and N (POM-N) contents in a high-yielding cropland in the North China Plain. Four treatments were installed, i.e., chemical NPK (CK), chemical NPK plus 2250 kg x hm(-2) of biochar (C1), chemical NPK plus 4500 kg x hm(-2) of biochar (C2), and 750 kg x hm(-2) of biochar-based slow release fertilizer (CN). Comparing with CK, treatments C1 and C2 significantly decreased the bulk density of 0-7.5 cm soil layer by 4.5% and 6.0%, respectively, and the treatments with biochar amendment increased the CEC in 0-15 cm soil layer, with an increment of 24.5% in treatment C2. Biochar amendment also increased the C (POM-C) and N (POM-N) contents in 0-7.5 cm soil layer, e.g., the POM-C and N contents in treatment C1 and C2 were 250% and 85%, and 260% and 120% higher than those of the CK, respectively. After three years of biochar amendment, the soil had obvious improvement in its physical and chemical properties, and played more active roles in soil carbon sequestration and greenhouse gases emission reduction. PMID:22303671

  6. 襄阳市农田土壤阳离子交换量的测定及分析%Measurement and analysis of farmland soil cation exchange capacity in Xiangyang

    Institute of Scientific and Technical Information of China (English)

    赵翔

    2016-01-01

    Soil cation exchange capacity ( CEC) can reflect the level of soil fertility, fertilizer retention capacity and buffering capacity. Throughinvestigation, sampling and laboratory analysis of soil cation exchange capacity of 16 spot in Xiangyang city, we discovered that the CEC of Xiangyang soil are concentrated in the 15-20 cmol/kg , which belongs to the medium fertility soil. At the same time, through the determination of soil physiochemical indexes, such as the content of soil organic matter,PH value, we discovery that they are very good cor-relation to soil cation exchange capacity.%土壤阳离子交换量CEC能够综合反映土壤肥力水平、保肥能力和缓冲能力。通过对襄阳市16个点位农田土壤实地调查、采集及实验室分析测定土壤阳离子交换量,发现襄阳市农田土壤阳离子交换量多集中在15-20 cmol/kg,属于中等偏上保肥能力土壤,同时通过测定土壤有机质含量,PH值等土壤理化指标,发现与土壤阳离子交换量存在很好的相关性。

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Directory of Open Access Journals (Sweden)

    Mosayeb Heshmati

    2011-01-01

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

  9. Recovery of soil pH, cation-exchange capacity and the saturation of exchange sites from stemflow-induced soil acidification in three Swedish beech (Fagus sylvatica L.) forests

    International Nuclear Information System (INIS)

    Stemflow water acidifies the soil in beech stands impacted by atmospheric deposition. To investigate whether the soil recovers from acidification, stemflow was experimentally removed. A horizon material was sampled at a distance of 10-250 cm from the stems. Before the onset of the experiment, there were stemflow-induced gradients in the saturation of exchange sites with K+, H+ and Na+ that were larger near the stems, while the pHKCl, the cation-exchange capacity, and the saturation with Ca2+, Mg2+ and Mn2+ were smaller. After 8 yrs of recovery, the pHKCl and the saturation with Ca2+ and Mg2+ had increased close to the stems, while the saturation with Na+, H+, Mn2+ and Fe2+ and the C/N ratio had decreased. With some exceptions, e.g. base saturation, the recovery was not complete after 8 yrs. Soil far from stems had also changed similarly, probably because of the ongoing decrease in overall deposition in southern Sweden

  10. Advancements in Anion Exchange Membrane Cations

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-15

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

  11. USE OF STRONG ACID RESIN PUROLITE C100E FOR REMOVING PERMANENT HARDNESS OF WATER – FACTORS AFFECTING CATIONIC EXCHANGE CAPACITY

    Directory of Open Access Journals (Sweden)

    BOGDAN BANDRABUR

    2013-12-01

    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%.

  12. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-11-15

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

  13. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    International Nuclear Information System (INIS)

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca2+ as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pKa2 (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d001) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water.

  14. Characterization of an aluminum pillared montmorillonite with cation exchange properties

    International Nuclear Information System (INIS)

    The methods of PIGE and XRF were used to determine the elemental composition and the structural formulae of a specially tailored PILC material during the steps of its preparation. The CEC, a crucial property for the characterization of a cation exchanger, was monitored through all stages of preparation. In addition, the charge carried by the pillars, a critical quantity of the pillaring process, was estimated. Exchange isotherms of strontium and cesium were performed through the use of radiotracers' exchange isotherms of 137Cs and 85Sr with typical γ-ray spectroscopy. These isotherms were of the Langmuir type and PILCs adsorption capacity was determined. The latter property was compared with the CEC determined by the elemental analysis and was found equal to the amount of the exchangeable interlamellar sodium ions. (author)

  15. Cobalt 60 cation exchange with mexican clays

    International Nuclear Information System (INIS)

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

  16. Modeling cation exchange using EQ3/6

    International Nuclear Information System (INIS)

    Geochemical modeling codes must be able to predict solid-solution and ion-exchange behavior of zeolites and smectites in order to design and assess strategies for containing and cleaning up toxic and/or radioactive wastes. Cation-exchange and solid-solution models have been implemented in the EQ3/6 geochemical modeling package and used to predict the composition of clinoptilolite under a variety of conditions. Published free energies of cation exchange on clinoptilolite at 25 degrees C were combined with the calorimetric data for clinoptilolite to derive free energies of formation of the component end members of a solid solution in which mixing is allowed only on the exchange site. The solid-solution model and component end-member data were incorporated into EQ3/6 and its data base. An option to treat cation exchange independently of the solid-solution model was also developed and implemented in EQ3/6. This option allows the user to model mixed-phase exchangers, multisite exchangers, and systems in which the exchanger is not in overall equilibrium with the solution. Two open-quotes idealclose quotes cation-exchange conventions [Vanselow (mole fraction) and Gapon (equivalent fraction)] are currently implemented in the code. A description of the cation-exchange models and their implementation into EQ3/6 is presented, and the relationship between the exchange formalisms and the solid-solution models is discussed. The advantages and limitations of the models and currently available thermodynamic data are addressed by comparing cation-exchange compositions of clinoptilolites with (1) published binary exchange data; (2) compositions of coexisting clinoptilolites and formation waters at Yucca Mountain; and (3) experimental sorption isotherms of Cs and Sr on zeolitized tuff

  17. 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.

    2001-12-01

    +, and Na+, on cation exchangeable capacity (CEC, and on base saturation (BS% of 21 acid and 5 alkaline soils. The organic compost (collected at the São Matheus Plant Treatment, São Paulo, Brazil was applied with or without dolomitic lime and mineral fertilizers. For alkaline soils, lime was substituted by gypsum. The experiment was carried out on a split-plot, completely randomized block design with three replicates. The compost application increased the exchangeable content of potassium, calcium, magnesium, and sodium on average of 195%, 200%, 86%, and 1200%, respectively, and elevated the CEC by 42% in acid soils. Consequently the BS% was increased 39%. A lower, but significant, increase on CEC was observed in alkaline soils in response to the compost application. Average CEC and BS% increases were of 8.4% and 2%, respectively. The highest effects on the evaluated soil properties were verified for compost + fertilizer + lime and compost + fertilizer + gypsum applications in acid and alkaline soils, respectively. It is concluded that the use of urban waste compost in agricultural lands is viable only if its effects on chemical properties are properly monitored.

  18. Microscopic Theory of Cation Exchange in CdSe Nanocrystals

    OpenAIRE

    Ott, Florian D.; Spiegel, Leo L.; Norris, David J.; Erwin, Steven C.

    2014-01-01

    Although poorly understood, cation-exchange reactions are increasingly used to dope or transform colloidal semiconductor nanocrystals (quantum dots). We used density-functional theory and kinetic Monte Carlo simulations to develop a microscopic theory that explains structural, optical, and electronic changes observed experimentally in Ag-cation-exchanged CdSe nanocrystals. We find that Coulomb interactions, both between ionized impurities and with the polarized nanocrystal surface, play a key...

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

    Directory of Open Access Journals (Sweden)

    Yin-lin Lei

    2014-07-01

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

  20. Synthetic crystalline calcium silicate hydrate (I): cation exchange and caesium selectivity

    International Nuclear Information System (INIS)

    Solid crystalline calcium silicate hydrate (I) synthesized from equimolar amounts of Ca and Si under hydrothermal conditions at 120 oC shows cation exchange properties towards divalent metal cations such as Ni, Cu, Cd, or Hg. It also exhibits caesium selectivity in the presence of Na+. The exchange capacity and selectivity of the solid can be increased by 10 and 28 %, respectively, upon substitution of 0.01 mol of the Ca2+ in its structure by Na+. The ability of metal cation uptake by the solid was found to obey the order Ni2+ > Hg2+ > Cu2+ > Cd2+. The different affinities of calcium silicate hydrate (I) towards these ions can be used for their separation from solutions and also in nuclear waste treatment. The mechanism of the exchange reaction is discussed. (author)

  1. Ligand Exchange Processes on Solvated Lithium Cations

    OpenAIRE

    Pasgreta, Ewa Maria

    2007-01-01

    In this work the solvation process of Li+ ion, as well as solvent and ligand exchange reactions on Li+ ion were studied. Li+ ions possess interesting properties and like other alkali metal ions are known to form complexes with macrocyclic ligands called cryptands. In this summary, an overview over the insights gained in the factors that control the reactivity of Li+ complexes with respect to the solvent and cryptand properties is presented. Three main questions were addressed: • How does the ...

  2. Simultaneous Determination of Anions and Cations in Natural Water by Ion-exclusion/Cation-exchange Chromatography with a Weakly Acidic Cation-exchange Resin Column

    International Nuclear Information System (INIS)

    The simultaneous determination of anions (SO4 2-, Cl-, and NO3 -) and cations (Na+, NH4+, K+, Mg2+, and Ca2+) in natural water obtained by Nakdong River waters system in Korea were performed by ion-exclusion/cation exchange chromatography with conductimetric detection. The stationary phase was a polymethacrylate-based weakly acidic cation-exchange resin column in the H+-form and a weak-acid eluent. When using only a 1.4 mM sulfosalicylic acid/6 mM 18-crown-6 ether as an eluent, good resolution of both anions and cations, minimum time required for the separation, and satisfactory detection sensitivity were obtained in a reasonable time. The method was successfully applied to the simultaneous determination of anions and cations in natural waters

  3. Simultaneous Determination of Anions and Cations in Natural Water by Ion-exclusion/Cation-exchange Chromatography with a Weakly Acidic Cation-exchange Resin Column

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kwang Pill; Choi, Seong Ho; Park, Yu Chul; Bae, Zun Ung; Lee, Mu Sang; Lee, Sang Hak; Chang, Hye Yong [Graduate School, Kyungpook National University, Daegu (Korea, Republic of); Kwon, Se Mok [Ulsan City Health and Environmental Research Institute, Ulsan (Korea, Republic of); Tanaka, Kazuhiko [National Industrial Research Institute of Nagoya, Nagoya (Japan)

    2003-09-15

    The simultaneous determination of anions (SO{sub 4} {sup 2-}, Cl{sup -}, and NO{sub 3} {sup -}) and cations (Na{sup +}, NH{sup 4+}, K{sup +}, Mg{sup 2+}, and Ca{sup 2+}) in natural water obtained by Nakdong River waters system in Korea were performed by ion-exclusion/cation exchange chromatography with conductimetric detection. The stationary phase was a polymethacrylate-based weakly acidic cation-exchange resin column in the H{sup +}-form and a weak-acid eluent. When using only a 1.4 mM sulfosalicylic acid/6 mM 18-crown-6 ether as an eluent, good resolution of both anions and cations, minimum time required for the separation, and satisfactory detection sensitivity were obtained in a reasonable time. The method was successfully applied to the simultaneous determination of anions and cations in natural waters.

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

    Institute of Scientific and Technical Information of China (English)

    LI Rong; CHEN Guo-Liang

    2003-01-01

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

  5. Some investigations on the radiation stability of a strongly acidic cation exchange resin

    Science.gov (United States)

    Dessouki, A. M.; Zahran, A. H.; Rabie, A. M.; Amer, S. I.

    The radiation-chemical stability of Merck Cation Exchanger I, a strongly acidic sulphonated cation exchanger of the polymerization type based on styrene-divinylbenze (DVB) copolymers was investigated. The radiation stability of the resin was assessed from the change in exchange capacity, loss in weight, change in swelling behaviour and formation of new exchange groups. The loss in capacity was 44 and 32% for resin specimens in the H +-form irradiated to 1000 Mrad in air and in vacuum, respectively. The Na +-form of the exchanger showed high resistance to radiation and the loss in capacity did not exceed 7% at a dose of 1000 Mrad. The loss in capacity was accompanied by a loss in weight and a decrease in the degree of swelling of the irradiated resin. The formation of new functional groups of the carboxylic and phenolic types was confirmed. The amount of these group increases with the increase in the integral dose. The amount of sulphuric acid formed as a result of irradiating the resin in the dry and moist states was determined. An increase in the moisture content of the resin resulted in a marked decrease in its radiation stability.

  6. Radiation stability of macro-porous and gel-type cation exchangers

    International Nuclear Information System (INIS)

    Macro-porous cation exchange resin Dianion CPK-08 and gel-type cation exchange resin Dowex 50WX8 were irradiated with γ-rays from 60Co, while soaked in distilled water, 0.5 M HNO3 or 4 M HNO3, and the ion-exchange properties, such as strong- and weak-acid capacities, moisture content and wet resin volume, were examined in relation to absorbed dose. There was no appreciable difference between the radiation stabilities of the two cation exchangers. Increase of HNO3 concentration reduced the loss of strong-acid capacity and increased the decross-linkage and the weak-acid capacity. Elution characteristics of 137Cs and 99Sr from columns packed with γ-irradiated resin were examined and the column distribution ratio of these radionuclides and the theoretical plate number were calculated. These values decreased with the increase of absorbed dose. Dianion CPK-08 was packed into a pressurized column and irradiated with γ-rays at a dose rate of 2x1O6 R/hr, while water was passed through the column at a constant flow rate. The greatest change in the resin properties was observed at an upper stream position from the position of the highest radiation dose of 2x106 R/hr. (T.G.)

  7. Effects of exchanged cation on the microporosity of montmorillonite

    Science.gov (United States)

    Rutherford, D.W.; Chiou, C.T.; Eberl, D.D.

    1997-01-01

    The micropore volumes of 2 montmorillonites (SAz- 1 and SWy-1), each exchanged with Ca, Na, K, Cs and tetramethylammonium (TMA) ions, were calculated from the measured vapor adsorption data of N2 and neo-hexane by use of t- and ??s-plots. The corresponding surface areas of the exchanged clays were determined from Brunauer-Emmett-Teller (BET) plots of N2 adsorption data. Micropore volumes and surface areas of the samples increased with the size of exchanged cation: TMA > Cs > K> Ca > Na. The SAz-1 exchanged clays showed generally greater micropore volumes and surface areas than the corresponding SWy-1 clays. The vapor adsorption data and d(001) measurements for dry clay samples were used together to evaluate the likely locations and accessibility of clay micropores, especially the relative accessibility of their interlayer spacing. For both source clays exchanged with Na, Ca and K ions, the interlayer spacing appeared to be too small to admit nonpolar gases and the accessible micropores appeared to have dimensions greater than 5.0 A??, the limiting molecular dimension of neo -hexane. In these systems, there was a good consistency of micropore volumes detected by N2 and neo-hexane. When the clays were intercalated with relatively large cations (TMA and possibly Cs), the large layer expansion created additional microporosity, which was more readily accessible to small N2 than to relatively large neo-hexane. Hence, the micropore volume as detected by N2 was greater than that detected by neo-hexane. The micropore volumes with pore dimensions greater than 5 A?? determined for clays exchanged with Na, Ca and K likely resulted from the pores on particle edges and void created by overlap regions of layers. The increase in micropore volumes with pore dimensions less than 5 A?? determined for clays exchanged with TMA and possibly Cs could be caused by opening of the interlayer region by the intercalation of these large cations.

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

    Science.gov (United States)

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

    2016-08-01

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

  9. Effect of α-irradiation on the properties of the phosphate cation exchange resin KFP

    International Nuclear Information System (INIS)

    The effect of α-irradiation in a solution of 2 M nitric acid on the properties of the cation-exchange resins KFP-8 and KFP-16 in the range of doses of irradiation up to 5.5 x 188 rad was investigated. It was shown that irradiation leads to a loss of porosity, a decrease in the mechanical strength of the grains, and dissolution of the resin in nitric acid. The exchange capacity of the resin with respect to phosphate groups is decreased: however, new functional groups with low basicity appear, which leads to an increase in the total exchange capacity when the resin is irradiated. The distribution coefficients of fragment elements between the resin and the nitric acid solutions are changed

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

    Science.gov (United States)

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

    2014-01-01

    Sorption performance of cation-exchange resins Amberlite® IRN77 and Amberlite™ IRN9652 toward Cs(I) and Sr(II) has been tested in single-component aqueous solutions and simulated waste effluents containing other monovalent (Effluent 1) or divalent (Effluent 2) metal cations, as well as nitrate, borate, or carbonate anions. The individual sorption isotherms of each main component were measured by the solution depletion method. The differential molar enthalpy changes accompanying the ion-exchange between Cs+ or Sr2+ ions and protons at the resin surface from single-component nitrate solutions were measured by isothermal titration calorimetry and they showed a higher specificity of the two resins toward cesium. Compared to the retention limits of both resins under such idealized conditions, an important depression in the maximum adsorption capacity toward each main component was observed in multication systems. The overall effect of ion exchange process appeared to be an unpredictable outcome of the individual sorption capacities of the two resins toward various cations as a function of the cation charge, size, and concentration. The cesium retention capacity of the resins was diminished to about 25% of the "ideal" value in Effluent 1 and 50% in Effluent 2; a further decrease to about 15% was observed upon concomitant strontium addition. The uptake of strontium by the resins was found to be less sensitive to the addition of other metal components: the greatest decrease in the amount adsorbed was 60% of the ideal value in the two effluents for Amberlite® IRN77 and 75% for Amberlite™ IRN9652. It was therefore demonstrated that any performance tests carried out under idealized conditions should be exploited with much caution to predict the real performance of cation exchange resins under conditions of cation competition. PMID:24728575

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

    Directory of Open Access Journals (Sweden)

    Dinar Dilshatovich Fazullin

    2014-01-01

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

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

    Science.gov (United States)

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

    2013-01-15

    Samples of high-silica SSZ-13, ion exchanged with protons and alkali-metal cations Li(+), Na(+), and K(+), were investigated using adsorption isotherms of CO(2) and N(2). The results show that Li-, Na-SSZ-13 have excellent CO(2) capacity at ambient temperature and pressure; in general, Li-SSZ-13 shows the highest capacity for N(2), CO(2) particularly in the low-pressure region. The effect of cation type and Si/Al ratio (6 and 12) on the adsorption properties was investigated through analysis of adsorption isotherms and heats of adsorption. The separation of CO(2) in a flue gas mixture was evaluated for these adsorbents in the pressure swing adsorption and vacuum pressure adsorption processes. PMID:23249267

  13. Cation exchange abilities of nanocomposites based on ion exchange resin and zirconium hydrophosphate

    International Nuclear Information System (INIS)

    A modification of cation-exchange resin with nanoparticles of zirconium hydrophosphate leads to the synergism of ion-exchange properties. The exchange of Cu2+→H+ shows that the nanocomposite ion exchangers demonstrate a high affinity to d-metal ions due to the polymer matrix, as well as to the inorganic component. The best characteristics are obtained for materials containing spherical particles of zirconium hydrophosphate with a diameter of (1.4-1.7) x 10-8 m, these aggregates being the most porous.

  14. Effects of exchanged cation and layer charge on the sorption of water and EGME vapors on montmorillonite clays

    Science.gov (United States)

    Chiou, C.T.; Rutherford, D.W.

    1997-01-01

    The effects of exchanged cation and layer charge on the sorption of water and ethylene glycol monoethyl ether (EGME) vapors on montmorillonite have been studied on SAz-1 and SWy-1 source clays, each exchanged respectively with Ca, Na, K, Cs and tetramethylammonium (TMA) cations. The corresponding lattice expansions were also determined, and the corresponding N2 adsorption data were provided for comparison. For clays exchanged with cations of low hydrating powers (such as K, Cs and TMA), water shows a notably lower uptake than does N2 at low relative pressures (P/P0). By contrast, EGME shows higher uptakes than N2 on all exchanged clays at all P/P0. The anomaly for water is attributed to its relatively low attraction for siloxane surfaces of montmorillonite because of its high cohesive energy density. In addition to solvating cations and expanding interlayers, water and EGME vapors condense into small clay pores and interlayer voids created by interlayer expansion. The initial (dry) interlayer separation varies more significantly with cation type than with layer charge; the water-saturated interlayer separation varies more with cation type than the EGME-saturated interlayer separation. Because of the differences in surface adsorption and interlayer expansion for water and EGME, no general correspondence is found between the isotherms of water and EGME on exchanged clays, nor is a simple relation observed between the overall uptake of either vapor and the cation solvating power. The excess interlayer capacities of water and of EGME that result from lattice expansion of the exchanged clays are estimated by correcting for amounts of vapor adsorption on planar clay surfaces and of vapor condensation into intrinsic clay pores. The resulting data follow more closely the relative solvating powers of the exchanged cations.

  15. Degradation of functional group of cation exchange nuclear grade resin loaded with different metal ions due to gamma radiation exposure

    International Nuclear Information System (INIS)

    Ion exchange resins undergo degradation due to ionizing radiation while processing the radioactive water treatment. During this process, the cation resin used for this purpose gets loaded with various metal ions and presence of different metal ions in the resin may result into different degradation behaviors of functional group(s) (lowering the capacity). This work deals with the effect of few cations such as H+, Li+, Na+, Cs+ and Cu2+ on the degradation behavior of functional groups of strong acid cation resins exposed in different dose of 60Co gamma ray. Degradations were estimated by measuring the sulphate ion concentration in leach solution. (author)

  16. Electron exchange involving a sulfur-stabilized ruthenium radical cation.

    Science.gov (United States)

    Shaw, Anthony P; Ryland, Bradford L; Norton, Jack R; Buccella, Daniela; Moscatelli, Alberto

    2007-07-01

    Half-sandwich Ru(II) amine, thiol, and thiolate complexes were prepared and characterized by X-ray crystallography. The thiol and amine complexes react slowly with acetonitrile to give free thiol or amine and the acetonitrile complex. With the thiol complex, the reaction is dissociative. The thiolate complex has been oxidized to its Ru(III) radical cation and the solution EPR spectrum of that radical cation recorded. Cobaltocene reduces the thiol complex to the thiolate complex. The 1H and 31P NMR signals of the thiolate complex in acetonitrile become very broad whenever the thiolate and thiol complexes are present simultaneously. The line broadening is primarily due to electron exchange between the thiolate complex and its radical cation; the latter is generated by an unfavorable redox equilibrium between the thiol and thiolate complexes. Pyramidal inversion of sulfur in the thiol complex is fast at room temperature but slow at lower temperatures; major and minor conformers of the thiol complex were observed by 31P NMR at -98 degrees C in CD2Cl2. PMID:17569530

  17. Effect of cation exchange of major cation chemistry in the large scale redox experiment at Aespoe. Revision 1

    International Nuclear Information System (INIS)

    Geochemical modeling was used to test the hypothesis that cation exchange with fracture-lining clays during fluid mixing in the Aespoe Hard Rock Laboratory can significantly affect major element chemistry. Conservative mixing models do not adequately account for changes in Na, Ca and Mg concentrations during mixing. Mixing between relatively dilute shallow waters and more concentrated waters at depth along fracture zones was modeled using the EQ3/6 geochemical modeling package. A cation exchange model was added to the code to describe simultaneously aqueous speciation, mineral precipitation/dissolution, and equilibration between a fluid and a cation exchanger. Fluid chemistries predicted to result from mixing were compared with those monitored from boreholes intersecting the fracture zone. Modeling results suggest that less than 0.1 equivalent of a smectite exchanger per liter of groundwater is necessary to account for discrepancies between predictions from a conservative mixing model and measured Na and Ca concentrations. This quantity of exchanger equates to an effective fracture coating thickness of 20 microm or less given a fracture aperture width of 1,000 microm or less. Trends in cation ratios in the fluid cannot be used to predict trends in cation ratios on the exchanger because of the influence of ionic strength on heterovalent exchange equilibrium. It is expected that Na for Ca exchange will dominate when shallow waters such as HBHO2 are mixed with deeper waters. In contrast, Na for Mg exchange will dominate mixing between deeper waters

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

    KAUST Repository

    Chen, Yifei

    2012-02-28

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

  19. On the determination of exchangeable cations in acid forest soils. Zur Bestimmung austauschbarer Kationen in sauren Waldboeden

    Energy Technology Data Exchange (ETDEWEB)

    Matzner, E. (Goettingen Univ. (Germany, F.R.). Forschungszentrum Waldoekosysteme); Buerstinghaus, C. (Goettingen Univ. (Germany, F.R.). Inst. fuer Bodenkunde und Waldernaehrung)

    1990-12-01

    Different samples from acid forest soils were percolated with large amounts of H{sub 2}O. Significant amounts of anions, especially sulfate, were found in the percolates mainly accompanied by Na, K, Ca and Mg (M{sub b}-cations). The dissolution of Al-sulfates and subsequent exchange of M{sub b}-cations by Al as dominant mechanism is proposed. Thus the common method for determination of the cation exchange capacity (CEC) of acid forest soils, the percolation with NH{sub 4}Cl may overestimate the CEC. The overestimation may be related to the sulfate content of the soil and also influences the calculation of relative CEC proportions of individual cations. (orig.).

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

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Santanu; Dang, Liem X.

    2016-03-03

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

  1. The importance of cerium substituted phosphates as cation exchanger some unique properties and related application potentials

    International Nuclear Information System (INIS)

    Seven different samples of an inorganic ion exchanger, cerium phosphate, suitable for column use have been prepared under varying conditions. The property of these exchangers has been characterized by Inductively Coupled Plasma Spectroscopy. These exchangers are stable in water, dilute mineral acids, ethanol, methanol, acetone and ether. However, in concentrated HCl and HNO3 they decompose. They retain about 50% of their exchange value after drying at 80 degC, and can be regenerated twice without any decrease in exchange capacity. The distribution coefficient measurements for alkaline earth metals, tellurium, iodine and molybdenum using these seven ion exchangers were studied. This revealed the relative affinity for each exchanger, where the sorption in general was most effective at P H 6-8. The titration curves of cerium phosphate (disodium) with alkaline earth metals showed that the selectivity sequence Ba2+>Sr2+>CA2+>Mg2+ is observed. Furthermore, it could be deduced that the adsorption of alkaline earth metal cations greatly depends on the cation. These studies have also shown that cerium phosphates with divalent ions are strongly preferred to monovalent ones. Therefore, as for the cerium phosphates with large monovalent ions, the lack of exchange for Ba2+, Mg2+ or other alkaline earth metal ions should be essentially due to steric hindrance and this could include any one of the following: the large crystalline radius of metal ions or large hydrated ionic radius and high energy of hydration for other divalent ions. Three binary separations of TeIV - MoIV, TeIV -I1 has been developed and the recovery ranging from 90 to 100% has been achieved on cerium phosphate (disodium) columns

  2. Modification of cation-exchange properties of activated carbon by treatment with nitric acid

    International Nuclear Information System (INIS)

    The uptake of inorganic cations by high-surface-area activated carbon can be increased by an order of magnitude by controlled exposure to high concentrations of nitric acid at elevated temperatures. Distribution coefficients of cations are also increased. Oxidation treatment causes some loss in particle strength. Acid strength of the functional groups from the nitric acid treatment is greater than those of the starting material. Surface area measurements from small-angle neutron scattering indicate that the increase in effective ion-exchange capacity is not accompanied by gross changes in the structure of the material. 13C-NMR on solid samples suggests that the concentration of carboxyl and phenolic functional groups in the carbon is increased by the treatment

  3. Soil exchangeable cations: A geostatistical study from Russia

    Directory of Open Access Journals (Sweden)

    Tayfun Aşkın

    2012-01-01

    Full Text Available In present study, geostatistical techniques was applied to assess the spatial variability of exchangeable cations such as; calcium (Ex-Ca2+, magnesium (Ex-Mg2+, potassium (Ex-K+ and sodium (Ex-Na+ in the tillaged layer in a Perm State Agricultural Academy Farm site in Perm region, West Urals, Russia. A 250x100 m plot (approximately 2.35 ha was divided into grids with 25x25 m spacing that included 51 sampling points from 0-0.2 m in depth. Soil reaction (pH was the least variable property while the Ex-K was the most variable. The greatest range of influence (237.6 m occurred for Ex-Ca and the least range (49.7 m for Ex-Mg.

  4. PEMFC contamination model: Foreign cation exchange with ionomer protons

    Science.gov (United States)

    St-Pierre, Jean

    2011-08-01

    A generic, transient fuel cell ohmic loss mathematical model was developed for the case of contaminants that ion exchange with ionomer protons. The model was derived using step changes in contaminant concentration, constant operating conditions and foreign cation transport via liquid water droplets. In addition, the effect of ionomer cations redistribution within the ionomer on thermodynamic, kinetic and mass transport losses and migration were neglected. Thus, a simpler, ideal, ohmic loss case is defined and is applicable to uncharged contaminant species and gas phase contaminants. The closed form solutions were validated using contamination data from a membrane exposed to NH3. The model needs to be validated against contamination and recovery data sets including an NH4+ contaminated membrane exposed to a water stream. A method is proposed to determine model parameters and relies on the prior knowledge of the initial ionomer resistivity. The model expands the number of previously derived cases. Most models in this inventory, derived with the assumption that the reactant is absent, lead to different dimensionless current vs. time behaviors similar to a fingerprint. These model characteristics facilitate contaminant mechanism identification. Separation between membrane and catalyst (electroinactive contaminant) contamination is conceivably possible using additional indicative cell resistance measurements. Contamination is predicted to be significantly more severe under low relative humidity conditions.

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

    Science.gov (United States)

    Fan, Zhaochuan; Lin, Li-Chiang; Buijs, Wim; Vlugt, Thijs J. H.; van Huis, Marijn A.

    2016-05-01

    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 pseudoligands to incorporate cation-ligand-solvent interactions in molecular dynamics. This leads to excellent agreement with experimental data on cation exchange of PbS nanocrystals, whereby Pb ions are partially replaced by Cd ions from solution. The temperature and the ligand-type control the exchange rate and equilibrium composition of cations in the nanocrystal. Our simulations reveal that Pb ions are kicked out by exchanged Cd interstitials and migrate through interstitial sites, aided by local relaxations at core-shell interfaces and point defects. We also predict that high-pressure conditions facilitate strongly enhanced cation exchange reactions at elevated temperatures. Our approach is easily extendable to other semiconductor compounds and to other families of nanocrystals.

  6. Surface area of lipid membranes regulates the DNA-binding capacity of cationic liposomes

    Science.gov (United States)

    Marchini, Cristina; Montani, Maura; Amici, Augusto; Pozzi, Daniela; Caminiti, Ruggero; Caracciolo, Giulio

    2009-01-01

    We have applied electrophoresis on agarose gels to investigate the DNA-binding capacity of cationic liposomes made of cationic DC-cholesterol and neutral dioleoylphosphatidylethanolamine as a function of membrane charge density and cationic lipid/DNA charge ratio. While each cationic liposome formulation exhibits a distinctive DNA-protection ability, here we show that such a capacity is universally regulated by surface area of lipid membranes available for binding in an aspecific manner. The relevance of DNA protection for gene transfection is also discussed.

  7. Iridium containing honeycomb Delafossites by topotactic cation exchange.

    Science.gov (United States)

    Roudebush, John H; Ross, K A; Cava, R J

    2016-06-01

    We report the structure and magnetic properties of two new iridium-based honeycomb Delafossite compounds, Cu3NaIr2O6 and Cu3LiIr2O6, formed by a topotactic cation exchange reaction. The starting materials Na2IrO3 and Li2IrO3, which are based on layers of IrO6 octahedra in a honeycomb lattice separated by layers of alkali ions, are transformed to the title compounds by a topotactic exchange reaction through heating with CuCl below 450 °C; higher temperature reactions cause decomposition. The new compounds display dramatically different magnetic behavior from their parent compounds - Cu3NaIr2O6 has a ferromagnetic like magnetic transition at 10 K, while Cu3LiIr2O6 retains the antiferromagnetic transition temperature of its parent compound but displays significantly stronger dominance of antiferromagnetic coupling between spins. These results reveal that a surprising difference in the magnetic interactions between the magnetic Ir ions has been induced by a change in the non-magnetic interlayer species. A combination of neutron and X-ray powder diffraction is used for the structure refinement of Cu3NaIr2O6 and both compounds are compared to their parent materials. PMID:27147423

  8. Enhanced DOC removal using anion and cation ion exchange resins.

    Science.gov (United States)

    Arias-Paic, Miguel; Cawley, Kaelin M; Byg, Steve; Rosario-Ortiz, Fernando L

    2016-01-01

    Hardness and DOC removal in a single ion exchange unit operation allows for less infrastructure, is advantageous for process operation and depending on the water source, could enhance anion exchange resin removal of dissolved organic carbon (DOC). Simultaneous application of cationic (Plus) and anionic (MIEX) ion exchange resin in a single contact vessel was tested at pilot and bench scales, under multiple regeneration cycles. Hardness removal correlated with theoretical predictions; where measured hardness was between 88 and 98% of the predicted value. Comparing bench scale DOC removal of solely treating water with MIEX compared to Plus and MIEX treated water showed an enhanced DOC removal, where removal was increased from 0.5 to 1.25 mg/L for the simultaneous resin application compared to solely applying MIEX resin. A full scale MIEX treatment plant (14.5 MGD) reduced raw water DOC from 13.7 mg/L to 4.90 mg/L in the treated effluent at a bed volume (BV) treatment rate of 800, where a parallel operation of a simultaneous MIEX and Plus resin pilot (10 gpm) measured effluent DOC concentrations of no greater than 3.4 mg/L, even at bed volumes of treatment 37.5% greater than the full scale plant. MIEX effluent compared to simultaneous Plus and MIEX effluent resulted in differences in fluorescence intensity that correlated to decreases in DOC concentration. The simultaneous treatment of Plus and MIEX resin produced water with predominantly microbial character, indicating the enhanced DOC removal was principally due to increased removal of terrestrially derived organic matter. The addition of Plus resin to a process train with MIEX resin allows for one treatment process to remove both DOC and hardness, where a single brine waste stream can be sent to sewer at a full-scale plant, completely removing lime chemical addition and sludge waste disposal for precipitative softening processes. PMID:26624231

  9. Influence of Types and Charges of Exchangeable Cations on Ciprofloxacin Sorption by Montmorillonite

    Institute of Scientific and Technical Information of China (English)

    WU Qingfeng; LI Zhaohui; HONG Hanlie

    2012-01-01

    As one of the most important soil components,montmorillonite plays a vital role in transport and retention of organic pollutants in soils.Ciprofloxacin (CIP),an antibiotic of fluoroquiolones,has been frequently detected in water and soil environments due to its wide use in human and veterinary medicine.In this study,the adsorption of CIP onto different homoionic montmorillonite such as Na-,Ca- and Al-MMT was investigated,and the influence of types and charges of exchangeable cations in the interlayer of montmorillonite on CIP adsorption was evaluated.The results showed that different homoionic montmorillonite exhibited different sorption capacity of CIP.At pH 3,the sorption capacity of CIP decreased in the order Na-MMT > Ca-MMT > Al-MMT,following the lyotropic series.When solution pH increased to 11,the sorption capacity of CIP followed the order Ca-MMT > Al-MMT > Na-MMT.Accompanying CIP adsorption on Ca-MMT,a certain amount of Ca2+ was released into solution.Compared to pH 3,the lower Ca concentration in solution at pH 11 indicated that the adsorption of CIP on Ca-MMT at strong alkaline pH was no longer via cation exchange,and surface complexation or cation bridging might contribute to CIP adsorption.The adsorption of CIP on Na-and Ca-MMT at pH 3 and 11 resulted in the expansion of d-spacing,indicative of intercalation of CIP into the interlayer space of the montmorillonite.However,a decrease of d-spacing was observed when CIP adsorbed on Al-MMT at pH 11,which might be attributed to the dissolution of Al-CIP complex formed between CIP and Al3+ in the interlayer of montmorillonite.The results suggest that the types and charges of exchangeable cations in the interlayer of montmorillonite play an important role in CIP adsorption on montmorillonite.

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

    Indian Academy of Sciences (India)

    Weqar Ahmad Siddiqui; Shakeel Ahmad Khan

    2007-02-01

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

  11. Study on degradation of cation exchange resin for condensate polishing plant

    International Nuclear Information System (INIS)

    The degradation of condensate polisher resin might cause the deterioration of water chemistry in power plants. The cause of cation resin degradation was studied in laboratory tests which simulated actual operating condition in a condensate polishing plant. It was found that air-scrubbing and unregenerated storage accelerate the decomposition of the cation exchange resin. Decrease of air-scrubbing times and regenerated storage are suggested as countermeasures against cation exchange resin degradation. (author)

  12. Sorption processes and XRD analysis of a natural zeolite exchanged with Pb2+, Cd2+ and Zn2+ cations

    International Nuclear Information System (INIS)

    In this study the Pb2+, Cd2+ and Zn2+ adsorption capacity of a natural zeolite was evaluated in batch tests at a constant pH of 5.5 by polluting this mineral with solutions containing increasing concentrations of the three cations to obtain adsorption isotherms. In addition X-ray powder diffraction (XRD) was used to investigate the changes of zeolite structure caused by the exchange with cations of different ionic radius. The zeolite adsorption capacity for the three cations was Zn > Pb > Cd. Moreover a sequential extraction procedure [H2O, 0.05 M Ca(NO3)2 and 0.02 M EDTA] was applied to zeolite samples used in the adsorption experiments to determine the chemical form of the cations bound to the sorbent. Using this approach it was shown that low concentrations of Pb2+, Cd2+ and Zn2+ were present as water-soluble and exchangeable fractions (27% of the Me adsorbed). The XRD pattern of zeolite, analysed according to the Rietveld method, showed that the main mineralogical phase involved in the adsorption process was clinoptilolite. Besides structure information showed that the incorporation of Pb2+, Cd2+ and Zn2+, into the zeolite frameworks changed slightly but appreciably the lattice parameters. XRD analysis also showed the occurrence of some isomorphic substitution phenomena where the Al3+ ions of the clinoptilolite framework were replaced by exchanged Pb2+ cations in the course of the ion exchange reaction. This mechanism was instead less evident in the patterns of the samples doped with Cd2+ and Zn2+ cations

  13. Cation-exchange separation of uranium in dimethylsulphoxide medium.

    Science.gov (United States)

    Janauer, G E; Korkisch, J; Hubbard, S A

    1971-08-01

    Cation-exchange chromatography in a dimethylsulphoxide (DMSO) medium is a suitable means for separating uranium from metal ions, including copper, iron, nickel and molybdenum. Quantitative separations of uranium from 26 elements can best be effected on a column of Dowex 50W-X8 (200-400 mesh), using as the eluent a 20% v/v DMSO solution which is 0.6Min hydrochloric acid and 0.25M in sodium acetate. Only calcium is eluted with the uranium and all other elements studied are eluted either before or after uranium. The elution characteristics of uranium and of other metal ions were investigated with respect to changes in eluent and resin compositions. Separations were much less effective at higher concentrations of sodium ion or DMSO. None of the organic solvents methanol, ethanol, methyl glycol, acetone, dioxan or acetic acid was found to produce favourable separation conditions. Results with Dowex 50 resins of lower or higher cross-linkage were inferior to those obtained with the X8 resin. PMID:18960944

  14. Uranium adsorption from the sulphuric acid leach liquor containing more chlorides with cation-exchange resin SL-406

    International Nuclear Information System (INIS)

    The feasibility of uranium adsorption was studied from the sulphuric acid leach liquor of a uranium ore containing more chlorides with cation-exchange resin SL-406. The influence of some factors on uranium adsorption was investigated. It was shown that the resin possesses better selectivity, stability and higher capacity. It can be effectively used to recovery uranium from leach liquors of uranium ores containing more chlorides

  15. Americium and samarium determination in aqueous solutions after separation by cation-exchange

    International Nuclear Information System (INIS)

    The concentration of trivalent americium and samarium in aqueous samples has been determined by means of alpha-radiometry and UV-Vis photometry, respectively, after chemical separation and pre-concentration of the elements by cation-exchange using Chelex-100 resin. Method calibration was performed using americium (241Am) and samarium standard solutions and resulted in a high chemical recovery for cation-exchange. Regarding, the effect of physicochemical parameters (e.g. pH, salinity, competitive cations and colloidal species) on the separation recovery of the trivalent elements from aqueous solutions by cation-exchange has also been investigated. The investigation was performed to evaluate the applicability of cation-exchange as separation and pre-concentration method prior to the quantitative analysis of trivalent f-elements in water samples, and has shown that the method could be successfully applied to waters with relatively low dissolved solid content. (author)

  16. Cation exchange reactions controlling desorption of 90Sr 2+ from coarse-grained contaminated sediments at the Hanford site, Washington

    Science.gov (United States)

    McKinley, J. P.; Zachara, J. M.; Smith, S. C.; Liu, C.

    2007-01-01

    Nuclear waste that bore 90Sr 2+ was accidentally leaked into the vadose zone at the Hanford site, and was immobilized at relatively shallow depths in sediments containing little apparent clay or silt-sized components. Sr 2+, 90Sr 2+, Mg 2+, and Ca 2+ was desorbed and total inorganic carbon concentration was monitored during the equilibration of this sediment with varying concentrations of Na +, Ca 2+. A cation exchange model previously developed for similar sediments was applied to these results as a predictor of final solution compositions. The model included binary exchange reactions for the four operant cations and an equilibrium dissolution/precipitation reaction for calcite. The model successfully predicted the desorption data. The contaminated sediment was also examined using digital autoradiography, a sensitive tool for imaging the distribution of radioactivity. The exchanger phase containing 90Sr was found to consist of smectite formed from weathering of mesostasis glass in basaltic lithic fragments. These clasts are a significant component of Hanford formation sands. The relatively small but significant cation exchange capacity of these sediments was thus a consequence of reaction with physically sequestered clays in sediment that contained essentially no fine-grained material. The nature of this exchange component explained the relatively slow (scale of days) evolution of desorption solutions. The experimental and model results indicated that there is little risk of migration of 90Sr 2+ to the water table.

  17. Synthesis, dehydration studies, and cation-exchange behavior of a new phase of niobium(V) phosphate

    International Nuclear Information System (INIS)

    Twenty-three samples of niobium(V) phosphate have been synthesized under different conditions using niobium sulfate and phosphoric acid solutions. The amorphous sample having the ion-exchange capacity of 1.06 mEq g-1 and niobium to phosphorus mole ratio of 0.670 was studied in detail for its cation-exchange behavior. Molar distribution coefficients for 25 cations have been studied on this gel at pH 1,2,3, and 5.5. Four quantitative separations of Mg2+-Ca2+, Mg2+-Ba2+, Zn2+-Cd2+, and Bi3+-Zn2+ have successfully been achieved on it. The properties of this sample have been compared with those of niobium arsenate, niobium antimonate, and niobium molybdate. A tentative structural formula is proposed for this sample of niobium phosphate on the basis of chemical composition, cation-exchange capacity, pH-titration, IR spectra, T.G.A., water absorption, and heat treatment data. (author)

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  19. The role of cation exchange in the sorption of cadmium, copper and lead by soils saturated with magnesium

    International Nuclear Information System (INIS)

    The displacement of Ca2+, Mg2+, K+ and Al3+ from the A and Bw or Bt horizons of two soils developed over serpentinized amphibolites when equilibrated in Cu2+, Cd2+ or Pb2+ solutions was determined, together with the concomitant sorption of the heavy metal. The contributions of Mg2+ to the effective cation exchange capacities of the A and Bt horizons of the Endoleptic Luvisol were 57% and 94%, respectively, and its contributions to those of the A and Bw horizons of the Mollic Cambisol were 70% and 77%, respectively. In all four horizons, cation exchange, chiefly with Mg2+ and Ca2+, was the process chiefly responsible for sorption of Cd2+, Cu2+ and Pb2+. Al3+ and K+ were hardly implicated, especially in the case of Cd2+.

  20. Measurement of the acidities of several cation-exchange resins using hydrogen-isotope exchange reaction

    International Nuclear Information System (INIS)

    The hydrogen-isotope exchange reaction between ethanol (unlabeled) and one of three cation-exchange resins labeled with tritium has been observed at 40-80degC. The acidity (acidity based on kinetic logic) at each temperature has been obtained from a A'-McKay plot based on the respective data obtained. The following results have been obtained on the basis of both the acidities obtained in this work and the acidities (of several materials) obtained previously. (1) The order of the reactivity is (Amberlite IRC-76)>(Dowex A-1)>(PVA2000>(Amberlite IRC-50) at 60degC. (2) The higher the temperature, the larger is the reactivity of each material. (3) The temperature dependence of the reactivity of Dowex A-1 is the largest in the four. (4) The reactivity of the functional group (i.e., COOH group or OH group) bonded to the polymer chain can be clarified using the A'-McKay plot method. (5) It seems that method can be applied to analyze other reactions, e.g., other isotope-exchange reactions, surface reactions, catalytic reactions, etc. (author)

  1. Aspects of the super-equivalent sorption of glycine by cation exchanger KU-2-8

    Science.gov (United States)

    Khokhlova, O. N.; Khokhlov, V. Yu.; Trunaeva, E. S.; Nechaeva, L. S.

    2016-07-01

    The structure formed in a sorbent during the super-equivalent sorption of glycine by cation exchanger KU-2-8 is optimized via quantum chemical simulation. The differential thermodynamic characteristics of ion exchange and super-equivalent sorption in the studied system are calculated using a thermodynamic approach that allows us to describe the simultaneous exchange and super-equivalent sorption of compounds by ion-exchangers.

  2. Ion exchange capacities and surface areas of some major components and common fracture filling materials of igneous rocks

    International Nuclear Information System (INIS)

    Surface/mass ratios have been determined by the ethylene glycol method and the BET-method, and an- and cation exchange capacities vs pH have been measured by an isotopic dilution technique for some 30-35 pure minerals. These minerals, which are representative of major components and common accessory minerals, including fracture minerals, of crystalline rocks, have also been used in radionuclide sorption studies within the Swedish waste program. Generally, the anion exchange capacities are low (< 1 meq/kg) for all the minerals. The cation exchange capacities, which increase with pH, are < 1 meq/kg for the non-silicates with few exceptions, 1-10 meq/kg for most of the silicates except the phyllosilicates and ranging from 10 up to 800 meq/kg for clay minerals (e.g. montmorillonite) and some of the zeolites (e.g. stilbite). (authors)

  3. Development of low cost ceramic separator using mineral cation exchanger to enhance performance of microbial fuel cells

    International Nuclear Information System (INIS)

    This study deals with the development of ceramic separator (CS) made from red soil blended with cation exchanger, Montmorillonite and Kaolinite, for its application in microbial fuel cells (MFCs). The separators were characterized in terms of conductivity, oxygen, acetate and proton diffusion, and ion transport ability. Performance of MFCs using different CS was evaluated under batch mode of operation. MFC M-20 (CS blended with 20% Montmorillonite) exhibited maximum power density of 7.5 W/m3 which was 48% higher than MFC without exchanger (Control) and 30%, 9%, 27% higher than MFC M-10 (10% Montmorillonite), MFC M-15 (15% Montmorillonite), MFC K-20 (20% Kaolinite), respectively. Coulombic efficiency of MFC M-20 (30%) and MFC K-20 (23%) was higher compared to control (18%). Use of cation exchangers improved properties of ceramic separators compared to control. Higher cation exchange capacity (CEC) of Montmorillonite (150 meq/100 g) resulted in 4 fold decrease in charge transfer resistance (3.4 Ω) and 1.8 fold increase in conductivity (5.56 × 10−4 S/cm) of CS as compared to Kaolinite. This study demonstrates that Montmorillonite incorporated CS proved to be suitable alternative to replace costly polymeric membrane to increase power output of MFC at reduced cost

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

    Institute of Scientific and Technical Information of China (English)

    I.S. Ismael; H.M. Baioumy

    2003-01-01

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

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

    Science.gov (United States)

    Fan, Zhaochuan; Lin, Li-Chiang; Buijs, Wim; Vlugt, Thijs J. H.; van Huis, Marijn A.

    2016-01-01

    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 pseudoligands to incorporate cation-ligand-solvent interactions in molecular dynamics. This leads to excellent agreement with experimental data on cation exchange of PbS nanocrystals, whereby Pb ions are partially replaced by Cd ions from solution. The temperature and the ligand-type control the exchange rate and equilibrium composition of cations in the nanocrystal. Our simulations reveal that Pb ions are kicked out by exchanged Cd interstitials and migrate through interstitial sites, aided by local relaxations at core–shell interfaces and point defects. We also predict that high-pressure conditions facilitate strongly enhanced cation exchange reactions at elevated temperatures. Our approach is easily extendable to other semiconductor compounds and to other families of nanocrystals. PMID:27160371

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

    International Nuclear Information System (INIS)

    Graphical abstract: Roles of exchangeable cations in PAHs photodegradation on clay surafces under visible light. - Highlights: • Photolysis rate are strongly dependent on the type of cations on clay surface. • The strength of “cation–π” interactions governs the photodegradation rate of PAHs. • Several exchangeable cations could cause a shift in the absorption spectrum of PAHs. • Exchangeable cations influence the type and amount of reactive intermediates. - Abstract: Clay minerals saturated with different exchangeable cations are expected to play various roles in photodegradation of polycyclic aromatic hydrocarbons (PAHs) via direct and/or indirect pathways on clay surfaces. In the present study, anthracene and phenanthrene were selected as molecule probes to investigate the roles of exchangeable cations on their photodegradation under visible light irradiation. For five types of cation-modified smectite clays, the photodegradation rate of anthracene and phenanthrene follows the order: Fe3+ > Al3+ > Cu2+ >> Ca2+ > K+ > Na+, which is consistent with the binding energy of cation–π interactions between PAHs and exchangeable cations. The result suggests that PAHs photolysis rate depends on cation–π interactions on clay surfaces. Meanwhile, the deposition of anthracene at the Na+-smectite and K+-smectite surface favors solar light absorption, resulting in enhanced direct photodecomposition of PAHs. On the other hand, smectite clays saturated with Fe3+, Al3+, and Cu2+ are highly photoreactive and can act as potential catalysts giving rise to oxidative radicals such as O2−· , which initiate the transformation of PAHs. The present work provides valuable insights into understanding the transformation and fate of PAHs in the natural soil environment and sheds light on the development of technologies for contaminated land remediation

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-28

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

  8. Reversible, Selective Trapping of Perchlorate from Water in Record Capacity by a Cationic Metal-Organic Framework.

    Science.gov (United States)

    Colinas, Ian R; Silva, Rachel C; Oliver, Scott R J

    2016-02-16

    We report the capture of ppm-level aqueous perchlorate in record capacity and kinetics via the complete anion exchange of a cationic metal-organic framework. Ambient conditions were used for both the synthesis of silver 4,4'-bipyridine nitrate (SBN) and the exchange, forming silver 4,4'-bipyridine perchlorate (SBP). The exchange was complete within 90 min, and the capacity was 354 mg/g, representing 99% removal. These values are greater than current anion exchangers such as the resins Amberlite IRA-400 (249 mg/g), Purolite A530E (104 mg/g), and layered double hydroxides (28 mg/g). Moreover, unlike resins and layered double hydroxides, SBN is fully reusable and displays 96% regeneration to SBN in nitrate solution, with new crystal formation allowing the indefinite cycling for perchlorate. We show seven cycles as proof of concept. Perchlorate contamination of water represents a serious health threat because it is a thyroid endocrine disruptor. This noncomplexing anionic pollutant is significantly mobile and environmentally persistent. Removal of other anionic pollutants from water such as chromate, pertechnetate, or arsenate may be possible by this methodology. PMID:26765213

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

    Directory of Open Access Journals (Sweden)

    Erik Ayala-Bribiesca

    2012-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

    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

  11. Some extra-high capacity heat exchangers of special design

    International Nuclear Information System (INIS)

    Recent technical advances in developing high-capacity power generating equipment, in using new heat transfer media, in seawater desalination, and in chemical processing require the development of higher unit-capacity heat exchangers. Up-to-date solutions illustrating the progress made in the development of such heat exchangers is discussed and suggestions are made which may be of interest in this field. Specific heat transfer systems discussed include systems for air-cooled condensing power plants, multiple reheating cycles for steam turbines, and systems using liquid lead as the transfer medium. (U.S.)

  12. Structure-Based Engineering of Lithium-Transport Capacity in an Archaeal Sodium-Calcium Exchanger.

    Science.gov (United States)

    Refaeli, Bosmat; Giladi, Moshe; Hiller, Reuben; Khananshvili, Daniel

    2016-03-29

    Members of the Ca(2+)/cation exchanger superfamily (Ca(2+)/CA) share structural similarities (including highly conserved ion-coordinating residues) while exhibiting differential selectivity for Ca(2+), Na(+), H(+), K(+), and Li(+). The archaeal Na(+)/Ca(2+) exchanger (NCX_Mj) and its mammalian orthologs are highly selective for Na(+), whereas the mitochondrial ortholog (NCLX) can transport either Li(+) or Na(+) in exchange with Ca(2+). Here, structure-based replacement of ion-coordinating residues in NCX_Mj resulted in a capacity for transporting either Na(+) or Li(+), similar to the case for NCLX. This engineered protein may serve as a model for elucidating the mechanisms underlying ion selectivity and ion-coupled alternating access in NCX and similar proteins. PMID:26958982

  13. Time reversal and exchange symmetries of unitary gate capacities

    OpenAIRE

    Harrow, Aram W.; Shor, Peter W.

    2005-01-01

    Unitary gates are an interesting resource for quantum communication in part because they are always invertible and are intrinsically bidirectional. This paper explores these two symmetries: time-reversal and exchange of Alice and Bob. We will present examples of unitary gates that exhibit dramatic separations between forward and backward capacities (even when the back communication is assisted by free entanglement) and between entanglement-assisted and unassisted capacities, among many others...

  14. Charge exchange of a polar molecule at its cation

    International Nuclear Information System (INIS)

    The Landau-Herring method is used to derive an analytic expression for the one-electron exchange interaction of a polar molecule with its positively charged ion, induced by a σ-electron. Analogously to the classical Van der Pole method, the exchange interaction potential is averaged over the rotational states of colliding particles. The resonant charge-transfer cross section is calculated, and the effect of the dipole moments of the core on the cross section is analyzed. It is shown that allowance for the dependence of the exchange potential on the orientation of the dipole moments relative to the molecular axis may change the dependence of the cross section on the velocity of colliding particles, which is typical of the resonant charge exchange, from the resonance to the quasi-resonance dependence.

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

    OpenAIRE

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

    2014-01-01

    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...

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

    Directory of Open Access Journals (Sweden)

    Ana Martínez

    2012-01-01

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

  17. Time reversal and exchange symmetries of unitary gate capacities

    CERN Document Server

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

    2005-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

  19. Contribuição de constituintes de solo à capacidade de troca de cátions obtida por diferentes métodos de extração Contribution of soil constituents to the cation exchange capacity as determined by different extraction methods

    Directory of Open Access Journals (Sweden)

    Edson Campanhola Bortoluzzi

    2009-06-01

    Full Text Available A capacidade de troca de cátions (CTC é uma propriedade físico-química intrínseca aos constituintes minerais e orgânicos do solo. Apesar do uso de diferentes extratores e procedimentos, a CTC é normalmente expressa considerando apenas o controle ou não do pH na solução extratora. O objetivo deste trabalho foi discutir o significado da contribuição da matéria orgânica do solo prepresentada pelo carbono orgânico total (COT e da argila à capacidade de troca de cátions de um Argissolo quando diferentes métodos estão envolvidos na determinação desse parâmetro. Para isso, utilizaram-se 75 amostras de um Argissolo Vermelho-Amarelo distrófico abrúptico da área do Departamento de Solos da Universidade Federal de Santa Maria, representando, em triplicata, cinco profundidades e cinco sistemas de uso e manejo de solo. A CTC efetiva (CTC E foi estimada pelo cloreto de hexamina cobalto (CTC E Cohex e pela soma de cátions Al3+, Ca2+, Mg2+ e K+ (CTC E SB + AlKCl, os três primeiros extraídos por KCl e o último por Mehlich-1; a CTC em pH 7,0 (CTC7 foi estimada por acetato de amônio (CTC7 Metson e pela soma de cátions Ca2+, Mg2+ e K+ e H + Al estimado pelo índice SMP (CTC7 SB + H + AlSMP. Os valores de CTC obtidos pelos diferentes métodos se relacionam entre si, com coeficientes de correlação linear simples acima de 0,93. Os valores de CTC7 Metson são subestimados quando comparados com o método CTC7 (SB + H + AlSMP. Nesse sentido, as contribuições da argila e do COT à CTC7 foram, respectivamente, menores para a CTC7 Metson, 19 e 256 cmol c kg-1, que para a CTC7 (SB + H + AlSMP, 23 e 399 cmol c kg-1. A contribuição dos constituintes de solo depende, então, do cátion extrator e da capacidade de extração dos métodos empregados.The cation exchange capacity (CEC is a physicochemical property dependent on mineral and organic soil constituents. Despite the use of different procedures and extractors the CEC is normally

  20. Differential enthalpy of cation exchange of alkaline metals on amorphous zirconium phosphate

    International Nuclear Information System (INIS)

    Work presents the results of calorimetric research of sorption process of alkaline metals cations on hydrogen form of amorphous zirconium phosphates. It is defined that the general regularities of passing of ion exchange reaction are the same for the samples of zirconium phosphate with different content of phosphor.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-06-01

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

  2. Purification of drinking water from radioactive contamination by final consumers by means of combined cation and anion exchangers

    International Nuclear Information System (INIS)

    It should be tried to develop an apparatus which makes it possible for the final consumer to purify the drinking water himself in the case of a radioactive contamination of the water. After thorough preliminary studies the most suitable kinds of exchange resins and the best arrangement for a combined cation and anion exchange resins and the best arrangement for a combined cation and anion exchange equipment were determined in inactive preliminary tests. Subsequent the useful capacity (NK) and the purifying factor (RF) were determined for the fission products 90Sr, 131I and 137Cs. The results were for 90Sr: NK = 30 1/2 x 0.5 l resin, RF >= 4.102, for 131I: NK = 32 1/2 x 0.5 l resin, RF = 3.7.102 and for 137Cs: NK > 35 1/2 x 0.5 l resin, RF >= 103. With 2 x 1 l resin the concentration of possible fission products in water can be reduced by 2 orders of magnitude ore more. A proposal for the construction of a household decontamination equipment for drinking water is made. The cost of production will be about A.S. 400,-- to 600,--. (author)

  3. Electrochemical ion exchanger in the water circuit to measure cation conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Bengtsson, Bernt; Ingemarsson, Rolf; Settervik, Gustav [Ringhals AB, Vaeroebacka (Sweden); Velin, Anna [Vattenfall Research and Development AB, Stockholm (Sweden)

    2011-03-15

    At Ringhals Nuclear Power Plant (NPP), more than four years of successful operation with a full-scale electrode ionization (EDI) unit for the recycling of steam generator blowdown gave the inspiration to modify and scale down this EDI process. As part of this project, the possibility of replacing the cation exchanger columns used for cation conductivity analysis with some small and integrated electrochemical ion exchange cells was explored. Monitoring the cation conductivity requires the use of a small cation resin column upstream of the conductivity probe and is one of the most important analyses at power plants. However, when operating with high alkaline treatment in the steam circuit, there is the disadvantage of rapid exhaustion of the resins, necessitating frequent replacement or regeneration. This causes interruptions in the monitoring and gives rise to a high workload for the maintenance staff. This paper reports on the optimization and testing of two different two-compartment electrochemical cells for possible replacement of the cation resin columns for analyzing cation conductivity in the secondary steam circuit at Ringhals NPP. Field tests during start-up conditions and more than four months of steady operation together with real and simulated tests for impurity influences indicate that an electrical ion exchange (ELIX) process could be successfully used to replace the resin columns in Ringhals while operating with high-pH all-volatile treatment (AVT) using hydrazine and ammonia. Installation of an ELIX system downstream of a particle filter and upstream of a small cation resin column will introduce additional safety and further reduce the maintenance and possible interruptions. Performance of the ELIX process together with other chemical additives (morpholine, ethanolamine, 3-methoxypropylamine, dimethylamine) and dispersants may be further evaluated to qualify the ELIX process as well as steam generator blowdown electrodeionization for wider use in

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

    Science.gov (United States)

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

    2013-11-01

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

  5. Synthesis and characterization of a novel hybrid material as amphoteric ion exchanger for simultaneous removal of cations and anions

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Brijesh, E-mail: brijeshshah27@gmail.com; Chudasama, Uma, E-mail: uvcres@gmail.com

    2014-07-15

    Highlights: • A novel hybrid exchanger ZrD (zirconium diethylene triamine) is synthesized for the first time. • Characterization and structure elucidation reveals that ZrD exhibits amphoteric character. • Amphoteric behaviour of ZrD is established by simultaneous removal of cations and anions. • Cations are exchanged in ZrD through chelation with nitrogen as coordinating sites. • ZrD can be regenerated and reused with not much decline in performance. - Abstract: 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{sup −}, Br{sup −}, Cr{sub 2}O{sub 7}{sup 2−}, F{sup −} and AsO{sub 4}{sup 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 K{sub d} for Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, Zn{sup 2+} (transition metal ions) and Hg{sup 2+}, Cd{sup 2+}, Pb{sup 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{sup 2+} and Cl{sup −} in CuCl{sub 2}. A study on the regeneration and reuse of ZrD indicates that it is effective upto four cycles without much decline in performance.

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

    CERN Document Server

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

    2016-01-01

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

  7. Electrochemical ion exchanger in the water circuit to measure cation conductivity

    International Nuclear Information System (INIS)

    In Ringhals NPP, more than four years of successful operation with a full-scale EDI for the recycling of steam generator blow down (SGBD) gave the inspiration to modify and 'scale down' this EDI process. This with purpose to explore the possibilities to replace the cation exchanger columns used for cation conductivity analysis, with some small and integrated electrochemical ion-exchange cells. Monitoring the cation conductivity requires the use of a small cation resin column upstream of the conductivity probe and is one of the most important analyses at power plants. However, when operating with high alkaline treatment in the steam circuit, it's connected to the disadvantage of getting the resins rapidly exhausted, with needs to be frequently replaced or regenerated. This is causing interruptions in the monitoring and giving rise to high workload for the maintenance. This paper reports about some optimization and tests of two different two-compartment electrochemical cells for the possible replacements of cation resin columns when analyzing cation conductivity in the secondary steam circuit at Ringhals NPPs. Field tests during start up condition and more than four months of steady operation together with real and simulated test for impurity influences, indicates that a ELectrical Ion Echange process (ELIX) could be successfully used to replace the resin columns in Ringhals during operating with high pH-AVT (All Volatile Treatment), using hydrazine and ammonia. Installation of an ELIX-system downstream a particle filter and upstream of a small cation resin column, will introduce additional safety and further reduce the maintenance with possible interruptions. Performance of the ELIX-process together with other chemical additives (Morpholine, ETA, MPA, DMA) and dispersants, may be further evaluated to qualify the ELIX-process as well as SGBD-EDI for wider use in nuclear applications. (author)

  8. Exchange of interlayer cations in micaceous minerals. Progress report, August 1, 1974--July 31, 1975

    International Nuclear Information System (INIS)

    Information pertaining to the sorption and exchange of interlayer cations in micaceous minerals was developed along several lines. Cs sorption experiments with different minerals and particle sizes established the periods required for maximum sorption at different temperatures and downgraded the impact anticipated from a contraction of particle edges by Cs. Added interlayer Cs in even highly charged minerals (degraded muscovite) proved to be very exchangeable in air-dry, clay size particles. Heat treatments greatly retarded the exchange of this sorbed Cs and by doing so have circumvented the commonly observed small particle effects. Structural Fe in micas was shown to be susceptible to oxidation by various Br2 treatments but these treatments also removed a lot of K that must be accounted for in a determination of changes in interlayer K exchangeability. Changes in the rate of interlayer K exchange were induced in some micaceous minerals by adding H2O2 but not in others. Specific effects of heat treatments on dioctahedral and trioctahedral micas were examined in great detail. Interlayer cation exchange experiments with different concentrations of Na and Al have produced predictable results. (U.S.)

  9. The sorption capacity of boron on anionic-exchange resin

    International Nuclear Information System (INIS)

    Boron sorption capacities on anionic-exchange resins vary with temperature, concentration, and resin cross-linkage. A semiempirical correlation, developed from boron solution chemistry, is presented to account for these variations. The relationship, based on boron chemistry and changes in Gibb's energy, can be stated approximately as Q = a1CBa2Za3 exp[-(a4T + a5T2 + a6Z0.5)]. Correlation parameters, which vary with resin type, are evaluated experimentally. Parameter values for macroporous resin Diaion PA 300 and for gel-type resins Diaion SA10 and Amberlite IRN 78LC are presented. The resulting expression is used to determine boron sorption and desorption limitations on ion exchangers at various temperatures and concentrations, and to determine the interfacial boron concentration in equilibrium and rate models

  10. Anion Exchange Capacity As a Mechanism for Deep Soil Carbon Storage in Variable Charge Soils

    Science.gov (United States)

    Dietzen, C.; James, J. N.; Ciol, M.; Harrison, R. B.

    2014-12-01

    Soil is the most important long-term sink for carbon (C) in terrestrial ecosystems, containing more C than plant biomass and the atmosphere combined. However, soil has historically been under-represented in C cycling literature, especially in regards to information about subsurface (>1.0 m) layers and processes. Previous research has indicated that Andisols with large quantities of noncrystalline, variable-charge minerals, including allophane, imogolite, and ferrihydrite, contain more C both in total and at depth than other soil types in the Pacific Northwest. The electrostatic charge of variable-charge soils depends on pH and is sometimes net positive, particularly in acid conditions, such as those commonly developed under the coniferous forests of the Pacific Northwest. However, even soils with a net negative charge may contain a mixture of negative and positive exchange sites and can hold some nutrient anions through the anion exchange capacity. To increase our understanding of the effects of variable-charge on soil organic matter stabilization, deep sampling is under way at the Fall River Long-Term Soil Productivity Site in western Washington. This site has a deep, well-drained soil with few rocks, which developed from weathered basalt and is classified as an Andisol of the Boistfort Series. Samples have been taken to a depth of 3 m at eight depth intervals. In addition to analyzing total soil C, these soils will be analyzed to determine functional groups present, cation exchange capacity, anion exchange capacity, and non-crystalline mineral content. These data will be analyzed to determine any correlations that may exist between these mineralogical characteristics, total soil C, and types of functional groups stored at depth. The most abundant organic functional groups, including carboxylic and phenolic groups, are anionic in nature, and soil positive charge may play an important role in binding and stabilizing soil organic matter and sequestering C.

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

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

  12. Cationic Covalent Organic Frameworks: A Simple Platform of Anionic Exchange for Porosity Tuning and Proton Conduction.

    Science.gov (United States)

    Ma, Heping; Liu, Bailing; Li, Bin; Zhang, Liming; Li, Yang-Guang; Tan, Hua-Qiao; Zang, Hong-Ying; Zhu, Guangshan

    2016-05-11

    Mimicking proton conduction mechanism of Nafion to construct novel proton-conducting materials with low cost and high proton conductivity is of wide interest. Herein, we have designed and synthesized a cationic covalent organic framework with high thermal and chemical stability by combining a cationic monomer, ethidium bromide (EB) (3,8-diamino-5-ethyl-6-phenylphenanthridinium bromide), with 1,3,5-triformylphloroglucinol (TFP) in Schiff base reactions. This is the first time that the stable cationic crystalline frameworks allowed for the fabrication of a series of charged COFs (EB-COF:X, X = F, Cl, Br, I) through ion exchange processes. Exchange of the extra framework ions can finely modulate the COFs' porosity and pore sizes at nanoscale. More importantly, by introducing PW12O40(3-) into this porous cationic framework, we can greatly enhance the proton conductivity of ionic COF-based material. To the best of our knowledge, EB-COF:PW12 shows the best proton conductivity at room temperature among ever reported porous organic materials. PMID:27094048

  13. Synthesis and characterization of a novel hybrid nano composite cation exchanger poly-o-toluidine Sn(IV) tungstate: Its analytical applications as ion-selective electrode

    Science.gov (United States)

    Khan, Asif Ali; Shaheen, Shakeeba

    2013-02-01

    A novel organic-inorganic nano composite cation exchanger poly-o-toluidine Sn(IV) tungstate has been synthesized by incorporation of a polymer material into inorganic precipitate. The material is a class of hybrid ion-exchanger with good ion-exchange properties, reproducibility, stability and good selectivity for heavy metals. The physico-chemical properties of this nano composite material were characterized by using XRD, TGA, FTIR, SEM and TEM. The ion-exchange capacity, pH titrations, elution behavior and chemical stability were also carried out to study ion-exchange properties of the material. Distribution studies for various metal ions revealed that the nano composite is highly selective for Cd(II). An ion-selective membrane electrode was fabricated using this material for the determination of Cd(II) ions in solutions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations.

  14. Biochemical characterization of Extracellular Polymeric Substances extracted from an intertidal mudflat using a cation exchange resin.

    OpenAIRE

    Pierre, Guillaume; Graber, Marianne; Orvain, Francis; Dupuy, Christine; Maugard, Thierry

    2010-01-01

    The biochemical characterization of Extracellular Polymeric Substances (EPS) excreted in a European intertidal mudflat (Marennes-Oléron Bay) was performed. Experiments were carried out for the first time in situ, by using an improved extraction recently developed. This innovative procedure, using a cation exchange resin (Dowex), allows separating precisely different fractions of EPS, especially pure bound EPS. Moreover, it avoids the contamination of EPS fractions by residual and intracellula...

  15. Effects of Experimental Conditions on Extraction Yield of Extracellular Polymeric Substances by Cation Exchange Resin

    OpenAIRE

    Jinwoo Cho; Hermanowicz, Slawomir W; Jin Hur

    2012-01-01

    Effects of experimental conditions on the yield of extracellular polymeric substances (EPSs) extraction by cation exchange resin (CER) were investigated using activated sludge flocs. The experimental variables included resin dose, extraction time, sample dilution, and storage time. An empirical model was proposed to describe the kinetics of extraction process. The extraction yield increases with the extraction time and CER dose until it reached the maximum amount of EPS extraction. The maximu...

  16. Cation-exchange membranes: comparison of homopolymer, block copolymer, and heterogeneous membranes

    Czech Academy of Sciences Publication Activity Database

    Schauer, Jan; Llanos, J.; Žitka, Jan; Hnát, J.; Bouzek, K.

    2012-01-01

    Roč. 124, SI 1 (2012), E66-E72. ISSN 0021-8995 R&D Projects: GA MŠk(CZ) 7E08005 EU Projects: European Commission(XE) 212903 - WELTEMP Institutional research plan: CEZ:AV0Z40500505 Keywords : cation-exchange membranes * poly(phenylene oxide) * poly(ether ketones) Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.395, year: 2012

  17. Method of producing weakly acidic cation exchange resin particles charged with uranyl ions

    Energy Technology Data Exchange (ETDEWEB)

    Abdelmonem, N.; Ringel, H.; Zimmer, E.

    1981-07-21

    Weakly acidic cationic ion exchange resin particles are charged with uranyl ions by contacting the particles step wise with aqueous uranyl nitrate solution at higher uranium concentrations from stage to stage. An alkaline medium is added to the uranyl nitrate solution in each stage to increase the successive pH values of the uranyl nitrate solution contacting the particles in dependence upon the uranium concentration effective for maximum charging of the particles with uranyl ions.

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

    Science.gov (United States)

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

    1993-01-01

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

  19. Exchangeable cation composition of the smectite-rich plate boundary fault at the Japan Trench

    Science.gov (United States)

    Kameda, Jun; Inaoi, Chisaki; Conin, Marianne

    2016-04-01

    To better understand physicochemical processes in smectite-rich fault zones, we examined exchangeable cation composition of samples from the slip zone of the 2011 Tohoku-oki earthquake (Mw9.0) recovered by the Integrated Ocean Drilling Program Expedition 343. Our chemical analyses revealed that the exchangeable Ca2+ and Mg2+ are enriched in the slip zone, while Na+ is depleted. K+ shows a complicated depth profile probably due to K fixation. Based on fluid chemistry data, we estimated apparent selectivity coefficients of exchange reactions in the ternary Ca2+-Mg2+-Na+ system. The results suggest that the Na+ to Mg2+ exchange reaction on smectite might have progressed in the slip zone. One explanation for this feature is local progress of the reaction triggered by coseismic thermogenesis during the earthquake. Considering that the frictional property of smectite gouge is dependent on the exchangeable cation composition, chemical processes as observed in this study are intimately linked to physical aspect of smectite-bearing faults.

  20. Cation Exchange in Dynamic 3D Porous Magnets: Improvement of the Physical Properties.

    Science.gov (United States)

    Grancha, Thais; Acosta, Alvaro; Cano, Joan; Ferrando-Soria, Jesús; Seoane, Beatriz; Gascon, Jorge; Pasán, Jorge; Armentano, Donatella; Pardo, Emilio

    2015-11-16

    We report two novel three-dimensional porous coordination polymers (PCPs) of formulas Li4{Mn4[Cu2(Me3mpba)2]3}·68H2O (2) and K4{Mn4[Cu2(Me3mpba)2]3}·69H2O (3) obtained-via alkali cation exchange in a single-crystal to single-crystal process-from the earlier reported anionic manganese(II)-copper(II) PCP of formula Na4{Mn4[Cu2(Me3mpba)2]3}·60H2O (1) [Me3mpba(4-) = N,N'-2,4,6-trimethyl-1,3-phenylenebis(oxamate)]. This postsynthetic process succeeds where the direct synthesis in solution from the corresponding building blocks fails and affords significantly more robust PCPs with enhanced magnetic properties [long-range 3D magnetic ordering temperatures for the dehydrated phases (1'-3') of 2.0 (1'), 12.0 (2'), and 20.0 K (3')]. Changes in the adsorptive properties upon postsynthetic exchange suggest that the nature, electrostatic properties, mobility, and location of the cations within the framework are crucial for the enhanced structural stability. Overall, these results further confirm the potential of postsynthetic methods (including cation exchange) to obtain PCPs with novel or enhanced physical properties while maintaining unaltered their open-framework structures. PMID:26492551

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

    Science.gov (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

    2015-10-01

    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.

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

    KAUST Repository

    Binetti, Enrico

    2015-10-27

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

  3. Esterification of oleic acid with ethanol catalyzed by sulfonated cation exchange resin: Experimental and kinetic studies

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Esterification of oleic acid with ethanol was investigated in the presence of sulfonated cation exchange resin. • We studied kinetic model of the esterification of oleic acid with ethanol according to experimental data. • The proposed kinetic model can well predict oleic acid conversion. - Abstract: This paper investigated the effects of ethanol to oleic acid molar ratio, reaction temperature, catalyst loading, water content and catalyst recycling on sulfonated cation exchange resin in a stirred batch reactor under atmospheric pressure. When the esterification was carried out with an ethanol to oleic acid (42.4 g) molar ratio of 9:1, reflux of ethanol at 82 °C, 20 g of catalyst and 8 h of reaction time, the oleic acid conversion rate reached approximately 93%. A pseudo-homogeneous kinetic model for describing the esterification of oleic acid with ethanol by the sulfonated cation exchange resin was developed on the basis of laboratorial results. The kinetic model can well predict the oleic acid conversion

  4. Contribuição dos constituintes da fração argila de solos subtropicais à área superficial específica e à capacidade de troca catiônica Contribution of clay fraction minerals of subtropical soils to the specific surface area and cation exchange capacity

    Directory of Open Access Journals (Sweden)

    Ivan Granemann de Souza Junior

    2007-12-01

    area (SSA is related to several properties that define the soil physico-chemical behavior. In this research, 23 soil samples developed from different parent materials found in the southern Brazil were used. They were evaluated for the contribution of the main soil constituents to the effective cation exchange capacity (CECe and SSA. The clay fraction minerals were identified by X ray diffraction (XRD and quantified by thermal analysis; the CECe, the SSAt (total by the ethylene glycol monoethyl ether method (EGME, the SSAe (external by the BET-N2 method, and the ASEi (internal by the difference of the values obtained with the two methods. The clay fraction samples were determined before and after the following sequential selective dissolution procedures: removal of organic matter (clay-NaOCl; removal of organic matter and free iron oxides (clay-NaOCl + DCB; removal of kaolinite, gibbsite and low cristalinity aluminosilicate minerals (clay-NaOCl+DCB + NaOH 5 mol L-1. The mineralogy of the clay fraction of the soils varied considerably, as verified by X ray diffraction, thermogravimetric analysis, and SSA and CECe values. For most soils kaolinite is the predominant mineral in the clay fraction, followed by expandable 2:1 clay mineral or iron and aluminum oxihydroxides. SSA and CECe of the natural clay fraction were not correlated due to the occlusion of the clay surface by organic matter. Iron oxide aggregate effects reduced SSAe by 21 %. For the studied samples, the 2:1 clay minerals were present in concentrations varying from 3 to 65 % of the silicate fraction and presented average values of 1.054 mmol c kg-1 and 202 m² g-1 for CECe and SSEt, respectively. SSAi contributed with 58 % of SSAt of the clay fraction, mostly due to 2:1 clay type minerals.

  5. Ion exchange kinetics of alkaline earth metals on acrylamide zirconium(IV) phosphate cation exchanger

    International Nuclear Information System (INIS)

    The kinetics of Mg(II), Ca(II), Sr(II) and Ba(II) exchange with H(I) on acrylamide zirconium(IV) phosphate has been studied applying the Nernst-Planck equation. The rate of exchange is found to be particle diffusion controlled at a metal ion concentration ≥ 0.01M in aqueous medium. The energy and entropy of activation vary linearly with the ionic radii and mobilities. (author)

  6. Extra-framework cation release from heulandite-type rich tuffs on exchange with NH(4)(+).

    Science.gov (United States)

    Kantiranis, N; Sikalidis, K; Godelitsas, A; Squires, C; Papastergios, G; Filippidis, A

    2011-06-01

    The outgoing cations of Greek heulandite-rich tuff samples (heulandite type-III, 91wt.%, mica 4wt.%, feldspar 5wt. %, CEC 2.22meq/g) were analysed upon exchange with ammonium acetate using atomic absorption spectrometry (AAS). The kinetic curves of each cation were investigated over a total time of contact of 720h with sampling at frequent intervals. The materials were examined by powder X-ray diffraction, SEM-EDS, and AAS. The sorption ability was measured using the ammonium acetate saturation method. It was found that Ca(2+) presents an unexpected extra-framework release and a surprisingly high degree of exchange (90%). The exchange of Mg (57%) is also worthy of note whereas the behavior of K(+) showed an expected rapid initial release. The behavior of Na(+) must be similar. However, its lower concentration in the zeolitic material minimizes its overall significance somewhat. On the other hand, Ca(2+) and Mg(2+) release is kinetically much slower, compared to that of alkali metal ions, and this phenomenon indicates that different exchange energies are needed till final equilibrium. PMID:21296480

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

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

    DEFF Research Database (Denmark)

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

    2004-01-01

    In this study we describe the design, preparation and testing of superparamagnetic anion-exchangers, and their use together with cation-exchangers in the fractionation of bovine whey proteins as a model study for high-gradient magnetic fishing. Adsorbents prepared by attachment of trimethyl amine...... aldehydes bound up to 337 mg g(-1) with a dissociation constant of 0.042 muM. The latter anion-exchanger was selected for studies of whey protein fractionation. In these, crude bovine whey was treated with a superparamagnetic cation-exchanger to adsorb basic protein species, and the supernatant arising from...

  9. Strongly reduced band gap in NiMn2O4 due to cation exchange

    International Nuclear Information System (INIS)

    NiMn2O4 is extensively used as a basis material for temperature sensors due to its negative temperature coefficient of resistance (NTCR), which is commonly attributed to the hopping mechanism involving coexisting octahedral-site Mn4+ and Mn3+. Using density-functional theory + Hubbard U calculations, we identify a ferrimagnetic inverse spinel phase as the collinear ground state of NiMn2O4. By a 12.5% cation exchange, a mixed phase with slightly higher energy can be constructed, accompanied by the formation of an impurity-like band in the original 1 eV band gap. This impurity-like band reduces the gap to 0.35 eV, suggesting a possible source of NTCR. - Highlights: • Density functional based calculations were used to study collinear phase of NiMn2O4. • The ground-state structure is a ferrimagnetic inverse spinel phase. • The tetrahedral and octahedral Mn cations have ferromagnetic interactions. • A 12.5% cation exchange introduces an impurity-like band in the original 1 eV gap. • The 0.35 eV gap suggests a source of negative temperature coefficient of resistance

  10. Erionite-Na upon heating: dehydration dynamics and exchangeable cations mobility

    Science.gov (United States)

    Ballirano, Paolo; Pacella, Alessandro

    2016-03-01

    Erionite is a fibrous zeolite significantly more tumorigenic than crocidolite asbestos upon inhalation. In recent years, several papers have been published aimed at characterizing from the crystal-chemical point of view erionite fibres. As their toxicity has been ascribed to Fe acquired within the human body, studies aimed at characterizing the iron topochemistry have also been published, suggesting a possible important role played by the ionic exchange properties and cations mobility of this zeolite on developing carcinogenicity. Here we report the analysis results of the thermal behaviour of erionite-Na, which has been found to deviate significantly from that of erionite-K. This result is in contrast with the current scientific view that differences in weighted ionic potential, Si/Al ratio and size of exchangeable cations result in significantly different thermal behaviours, all those parameters being nearly identical or very similar in both species. The different mobility of the extraframework cations observed in erionite samples with dissimilar chemistry is of particular interest within the frame of the hypothesis that their biological activity could depend, apart from surface interactions, also on bulk effects.

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

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

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

  12. Synthesis and characterization of a new inorganic cation-exchanger-Zr(IV) tungstomolybdate: Analytical applications for metal content determination in real sample and synthetic mixture

    International Nuclear Information System (INIS)

    An amorphous sample of inorganic cation-exchanger Zr(IV) tungstomolybdate was prepared by mixing varying ratios of 0.1 M aqueous solution of sodium tungstate and 0.1 M aqueous solution of sodium molybdate into 0.1 M aqueous solution of zirconium oxychloride at pH 1. This cation-exchanger was found to have a good ion-exchange capacity (2.40 mequiv. g-1 for Na+), high thermal and chemical stability. A tentative structural formula was proposed on the basis of chemical composition, FTIR and thermogravimetric analysis. Distribution coefficients (K d) values of metal ions in various solvent systems were determined. Some important and analytically difficult quantitative binary separations viz. Ni(II)-Pb(II), Ni(II)-Zn(II), Ni(II)-Cd(II), Mg(II)-Al(III), etc. were achieved. The practical applicability of the cation-exchanger was demonstrated in the separation of Cu(II)-Zn(II) from a synthetic mixture as well as from real samples of pharmaceutical formulation and brass alloy

  13. Assessing the role of cation exchange in controlling groundwater chemistry during fluid mixing in fractured granite at Aespoe, Sweden

    International Nuclear Information System (INIS)

    Geochemical modeling was used to simulate the mixing of dilute shallow groundwater with deeper more saline groundwater in the fractured granite of the Redox Zone at the Aespoe underground Hard Rock Laboratory (HRL). Fluid mixing simulations were designed to assess the role that cation exchange plays in controlling the composition of fluids entering the HRL via fracture flow. Mixing simulations included provision for the effects of mineral precipitation and cation exchange on fluid composition. Because the predominant clay mineral observed in fractures in the Redox Zone has been identified as illite or mixed layer illite smectite, an exchanger with the properties of illite was used to simulate cation exchange. Cation exchange on illite was modeled using three exchange sites, a planar or basal plane site with properties similar to smectite, and two edge sites that have very high affinities for K, Rb, and Cs. Each site was assumed to obey an ideal Vanselow exchange model, and exchange energies for each site were taken from the literature. The predicted behaviors of Na, Ca, and Mg during mixing were similar to those reported in a previous study in which smectite was used as the model for the exchanger. The trace elements Cs and Rb were predicted to be strongly associated with the illite exchanger, and the predicted concentrations of Cs in fracture fill were in reasonable agreement with reported chemical analyses of exchangeable Cs in fracture fill. The results of the geochemical modeling suggest that Na, Ca, and Sr concentrations in the fluid phase may be controlled by cation exchange reactions that occur during mixing, but that Mg appears to behave conservatively. There is currently not enough data to make conclusions regarding the behavior of Cs and Rb

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

    DEFF Research Database (Denmark)

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

    2003-01-01

    A method for the determination of arsenic species in marine samples using high performance liquid chromatography coupled to inductively coupled mass spectrometry (HPLC-ICP-MS) has been developed. Cation exchange HPLC with gradient elution using pyridine formate as the mobile phase was employed for...... the separation of a large number of arsenicals that occurred in the samples. The arsenic species were extracted using a 50% (v/v) methanol-water mixture and mechanical agitation overnight. The effect of the sample matrix on HPLC retention time was investigated and showed a dramatic effect for...

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

    Institute of Scientific and Technical Information of China (English)

    Yan WANG; Bo Lin GONG; Xin Du GENG

    2003-01-01

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

  16. Advance chromatin extraction enhances performance and productivity of cation exchange chromatography-based capture of Immunoglobulin G monoclonal antibodies.

    Science.gov (United States)

    Nian, Rui; Gagnon, Pete

    2016-07-01

    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 to<1 ppb, histones became undetectable, non-histones were reduced to 24,000ppm, and aggregates 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. PMID:27247214

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

    Institute of Scientific and Technical Information of China (English)

    卫引茂; 陈强; 耿信笃

    2001-01-01

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

  18. Effects of biofouling on ion transport through cation exchange membranes and microbial fuel cell performance.

    Science.gov (United States)

    Choi, Mi-Jin; Chae, Kyu-Jung; Ajayi, Folusho F; Kim, Kyoung-Yeol; Yu, Hye-Weon; Kim, Chang-Won; Kim, In S

    2011-01-01

    This study examines the effects of biofouling on the electrochemical properties of cation exchange membranes (CEMs), such as membrane electrical resistance (MER), specific proton conductivity (SC), and ion transport number (t(+)), in addition to on microbial fuel cell (MFC) performance. CEM biofouling using a 15.5 ± 4.6 μm biofilm was found to slightly increase the MER from 15.65 Ω cm(2) (fresh Nafion) to 19.1 Ω cm(2), whereas an increase of almost two times was achieved when the electrolyte was changed from deionized water to an anolyte containing a high cation concentration supporting bacterial growth. The simple physical cleaning of CEMs had little effect on the Coulombic efficiency (CE), whereas replacing a biofouled CEM with new one resulted in considerable increase of up to 59.3%, compared to 45.1% for a biofouled membrane. These results clearly suggest the internal resistance increase of MFC was mainly caused by the sulfonate functional groups of CEM being occupied with cations contained in the anolyte, rather than biofouling itself. PMID:20659795

  19. Purification of urokinase by combined cation exchanger and affinity chromatographic cartridges.

    Science.gov (United States)

    Hou, K C; Zaniewski, R

    1990-02-23

    Crude urokinase from human urine processed through foam flotation and ammonium sulfate precipitation containing 720 National Health Institute Committee on Thrombolytic Agents U/mg activity was purified by an SP cation exchanger followed by a zinc-chelated affinity chromatographic cartridge. The cartridges were of a radial-flow type formed by using acrylic and cellulose composite matrices. The high rigidity of the matrix structure permits fast flow of protein solutions (liters per minute) and thus allows processing of a large volume of crude urokinase under low operating pressures. A greater than six-fold increase in specific enzyme activity of urokinase was achieved by adsorbing and eluting 1 l of a 3 mg/ml crude urokinase solution on an SP cartridge. The eluent was further purified by passing through a zinc-chelated affinity cartridge to achieve greater than a eighteen-fold increase in urokinase specific activity. This report demonstrates the combined use of a cation exchanger with zinc-chelated chromatographic cartridges in purifying urokinase on a relatively large scale. The relationship between the amount of zinc chelated in the matrix to its effect on urokinase purification is also discussed. PMID:2329161

  20. Light-induced cation exchange for copper sulfide based CO2 reduction.

    Science.gov (United States)

    Manzi, Aurora; Simon, Thomas; Sonnleitner, Clemens; Döblinger, Markus; Wyrwich, Regina; Stern, Omar; Stolarczyk, Jacek K; Feldmann, Jochen

    2015-11-11

    Copper(I)-based catalysts, such as Cu2S, are considered to be very promising materials for photocatalytic CO2 reduction. A common synthesis route for Cu2S via cation exchange from CdS nanocrystals requires Cu(I) precursors, organic solvents, and neutral atmosphere, but these conditions are not compatible with in situ applications in photocatalysis. Here we propose a novel cation exchange reaction that takes advantage of the reducing potential of photoexcited electrons in the conduction band of CdS and proceeds with Cu(II) precursors in an aqueous environment and under aerobic conditions. We show that the synthesized Cu2S photocatalyst can be efficiently used for the reduction of CO2 to carbon monoxide and methane, achieving formation rates of 3.02 and 0.13 μmol h(-1) g(-1), respectively, and suppressing competing water reduction. The process opens new pathways for the preparation of new efficient photocatalysts from readily available nanostructured templates. PMID:26479775

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

    Directory of Open Access Journals (Sweden)

    César A. C. Sequeira

    2012-07-01

    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.

  2. Effect of ionophores on the rate of intramolecular cation exchange in durosemiquinone ion pairs

    Science.gov (United States)

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

    1979-01-01

    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.

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

    KAUST Repository

    Casu, Alberto

    2016-01-27

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

  4. The treatment of liquid radioactive waste containing Americium by using a cation exchange method

    International Nuclear Information System (INIS)

    A research in the treatment of a liquid radioactive waste containing americium has been done. The liquid radioactive waste used in this research was standard solution of U dan Ce with the initial activity of 100 ppm. The experimental investigation is aimed at a study of the effects of the waste pH, the column dimension of IR-120 cation exchanger which is expressed as L/D, the flow rate of a liquid waste and the influence of thiocyanate as a complex agent against the efficiency of a decontamination for uranium and cerium element. The experiment was done by passing downward the feed of uranium and cerium solution into an IR-120 type of cation exchanger with the L/D of 11.37. From the experimental parameters done in this research where the influence of waste pH was varied from 3 - 8, the geometric column (L/D) 11.37, the liquid flow rate was from 2.5 - 10 ml/m and the thiocyanate concentration was between 100 ppm-500 ppm can be concluded that the optimum operational condition for the ion exchange achieved were the waste pH for uranium = 4 and the waste pH for cerium = 6, the flow rate = 2.5 ml/men. From the given maximum value of DF for uranium = 24 (DE = 95.83%) and of DF for cerium = 40 (DE = 97.5%), it can also be concluded that this investigation is to be continued in order that the greater value of DF/DE can be achieved

  5. Comparative study of the ionic exchange of Ca++, Sr++, and Ba++ cations on resins and inorganic exchangers

    International Nuclear Information System (INIS)

    With a view to applying the results to certain problems related to chemical separations in activation analysis, a study has been made, of the possibilities of separating the alkaline-earth elements Ca, Sr and Ba on organic resins and inorganic exchangers using the radioactive indicator method. The partition coefficients of the cations Ca2+, Sr2+ and Ba2+ have been measured on Dowex 50 W (NH4+) x 8 resin in the presence of EDTA - NTA - EGTA and DCTA as complexing agents, and on zirconium phosphate, tungstate and molybdate in the presence of HCl and NH4Cl. Methods have been developed for separating mixtures of alkaline-earth elements using DCTA-NH4+ followed by elution on Dowex 50 W (NH4+) x 8 resin columns and on zirconium phosphate. Amongst the complexing agents used on the ion-exchange resins the most promising appears to be DCTA which leads to partition coefficients Ca, Sr and Ba which are very different. The results of measurements of partition coefficients on zirconium phosphate (NH4+ form) using DCTA-NH4+ show the interesting possibilities of separations on columns. The separation of the alkaline-earth elements on zirconium phosphate seems to be less quantitative than on Dowex 50 resin; it is however much faster in the former case and this can be useful for treating short half-life radioisotopes in activation analysis. (author)

  6. Studies on ion exchange equilibria and kinetics. Pt. 5. UO22+-Na+-H+ ternary cation exchange kinetics

    International Nuclear Information System (INIS)

    The kinetics of particle-diffusion controlled ion exchange in the ternary system of cations UO22+-Na+-H+ - 001 * 7 strong acidic resin has been studied. In the [R-H+]/Na++UO22+) system, the change of the amount of Na+ in the resin phase with time showed a high peak. In the [R-Na+]/H++UO22+) system, the change of the amount of H+ in the resin phase with time also showed a high peak. In the [R2-UO22+]/(H++Na+) system, the change of the amount of H+ in the resin phase with time showed a merely small peak. This kinetic character of the ternary ion exchange system in the finite solution volume has been analyzed according to the Nerst-Planck equation, and on the whole, the trend of the experimental results is consistent with the resulting numerical solution of the set of Nerst-Planck equations. (author) 11 refs.; 9 figs.; 1 tab

  7. Modeling of cesium sorption on biotite using cation exchange selectivity coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Kylloenen, Jarkko; Hakanen, Martti; Harjula, Risto; Lehto, Jukka [Helsinki Univ. (Finland). Lab. of Radiochemistry; Lindberg, Antero [Geological Survey of Finland, Espoo (Finland); Vehkamaeki, Marko [Helsinki Univ. (Finland). Lab. of Inorganic Chemistry

    2014-07-01

    For the modeling of cesium sorption on biotite, samples of natural biotite separated from gneissic rocks were converted into monoionic potassium, sodium, and calcium forms, and sorption isotherms for Cs/K, Cs/Na and Cs/Ca exchange were determined at pH 6 and 8 in 10{sup -4}-10{sup -8} M Cs solutions. Selectivity coefficients for Cs/K, Cs/Na, and Cs/Ca ion exchange reactions were calculated from the isotherm data, using the Gaines-Thomas convention. At Cs loadings below 1% of the total ion exchange capacity, the overall selectivity coefficient for Cs/Ca exchange was approximately five and seven orders of magnitude higher than those for Cs/Na and Cs/K exchange, respectively. Based on the selectivity coefficients, the ion exchange isotherms were modeled with the U.S. Geological Survey PhreeqC program, assuming three different types of ion exchange site: sites on the basal planes on biotite crystal surfaces with 95% site abundance, probable interlayer sites on crystal edges [frayed edge sites (FESs)] (0.02%) and third-type sites (5%), the physical background of which is unclear. Of these three types, the FES sites were superior in Cs selectivity, while the planar sites exhibited the lowest selectivity, and the third-type sites had selectivity between these two. The functionality of the model was successfully verified by modeling the Cs sorption isotherms on crushed mica gneiss rock in saline groundwater. Determination of the exchangeable ions K, Na, Ca, and Cs on the basal plane and edge surfaces by scanning electron microscopy-energy-dispersive x-ray spectroscopy (SEM-EDX) supports the results of modeling: edge sites highly prefer Cs ions and also Ca and Na ions but not K ions.

  8. Salbutamol versus cation-exchange resin (kayexalate) for the treatment of nonoliguric hyperkalemia in preterm infants.

    Science.gov (United States)

    Yaseen, Hakam; Khalaf, Mona; Dana, Ahmed; Yaseen, Noha; Darwich, Maha

    2008-03-01

    Our objective was to compare the efficacy and safety of rectal cation-exchange resin (Kayexalate) versus salbutamol infusion for the treatment of nonoliguric hyperkalemia (NOHK) in preterm infants. Data of all neonates born with NOHK during the study period of 6 years and 8 months were recorded. Diagnostic criteria of NOHK included serum potassium (SK) concentration > or = 7 mmol/L during the first 72 hours of life with urine output > or = 1 mL/kg/hour. This before-after study was divided according to the date of admission; the first 15 patients were treated with Kayexalate enema 1 g/kg every 4 hours, and the remaining 30 patients were treated with intravenous salbutamol infusion as 4 mug/kg every 4 hours. Treatment discontinued when SK became < 6 mmol/L. SK was measured every 4 hours. Daily urine was collected. Fluid intake and output, serum electrolytes, urea, creatinine, and glucose concentrations were obtained in all infants every 12 hours. All infants were observed with a cardiorespiratory monitor and oxygen saturation and blood pressure measurements. Perinatal characteristics in both groups were comparable. Mean gestational age was 26 and 28 weeks for salbutamol and Kayexalate, respectively. The peak of SK ranged between 7 and 9.3 mmol/L in the Kayexalate group and between 7 and 8.7 mmol/L in the salbutamol group ( P = 0.64). At 12 hours of treatment, SK became normal in only 4 patients (26%) in the Kayexalate group compared with 18 patients (60%) in the salbutamol group ( P = 0.003). The number of doses of Kayexalate administration was significantly higher than the doses of salbutamol ( P = 0.003). No significant side effects were detected in the salbutamol-treated infants. In contrast, there were two cases of severe ventricular tachycardia and one case of intestinal obstruction in the cation-exchange resin group. We concluded that salbutamol infusion is more effective with faster action and safer than cation-exchange resin (Kayexalate) for the treatment of

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

    Directory of Open Access Journals (Sweden)

    Stefan L.

    2013-07-01

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

  10. DecorporatinC facilities of cation-exchange resins with different characteristics on radioactive strontium

    International Nuclear Information System (INIS)

    Efficiency in promoting radiostrontium elimination from the body was studied comparatively for cation-exchange resins differing in type of exchanging moieties, mesh sizes, or extent of cross-linkage in the polymere molecule. The experiments were performed on rats receiving each an oral dose of 5 μCi or 85Sr in a 10 μCi/ml aqueous solution of strontium bichloride. The resins, suspended in sodium carboxymethyl cellulose solution, were administered either 10 or 30 minutes after radionuclide ingestion. From 2 hours to 72 hours after treatment, the animals were whole-body counted, and shortly thereafter their femur radioactivity was measured. All of the resin types tested were found to decrease strontium body burdens, with Amberlite IR-120 and Amberlite IRC-50 showing the most favourable effect. Tne efficiency of the resins did not appear to depend on the type of ion-exchange site. Similarly, no relation was observed with the amount of cross-linkage. It was the resins with minimum mesh sizes that proved more effective. (A.B.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-06

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

  12. High-capacity, selective solid sequestrants for innovative chemical separation: Inorganic ion exchange approach

    International Nuclear Information System (INIS)

    The approach of this task is to develop high-capacity, selective solid inorganic ion exchangers for the recovery of cesium and strontium from nuclear alkaline and acid wastes. To achieve this goal, Pacific Northwest Laboratories (PNL) is collaborating with industry and university participants to develop high capacity, selective, solid ion exchangers for the removal of specific contaminants from nuclear waste streams

  13. Complexation of americium(III) with humic acid by cation exchange and solvent extraction

    International Nuclear Information System (INIS)

    Complexation of Am(III) with humic acid was studied at various pHs in 0.1M NaClO4. The stability constants of the Am(III)-humate complexes were determined by a cation-exchange method. The values of logβ1 and logβ2 increased slightly with increases of pH from 4 to 6 and were found to be 6.9 and 11.6, respectively, at a pH of 5. Markedly larger values than these were obtained by a solvent extraction method. This discrepancy was also revealed by summarizing data from several literature sources. It is very likely that this can be ascribed to decreases in either humic acid and/or the extractant from the extraction system due to humate interactions at the aqueous-organic interface. (author)

  14. Potential sources of errors in cation-exchange chromatographic measurement of plasma taurine.

    Science.gov (United States)

    Connolly, B M; Goodman, H O

    1980-03-01

    We examined the potential sources of error in automated cation-exchange chromatographic quantitation of plasma taurine, both in sample preparation and in the analysis. Principal sources of error include: use of serum instead of plasma, which produces gross overestimates; use of tripotassium ethylenediaminetetraacetate (EDTA) as anticoagulant in systems involving ninhydrin detection (a ninhydrin-positive contaminant of EDTA emerges coincident with taurine); contamination with platelets; and placing volumes exceeding 20 microL on the cartridge used in the Technicon TSM Amino Acid Analyzer. We arrived at a simple technique in which we use EDTA as anticoagulant, micropore filtration to produce platelet-free plasma, and o-phthalaldehyde as the detection reagent for the sensitivity required to measure accurately the low concentration of taurine in plasma. PMID:6767571

  15. Electrochemical catalytic treatment of wastewater by metal ion supported on cation exchange resin

    International Nuclear Information System (INIS)

    The electrochemical oxidation of phenol in synthetic wastewater and paper mill wastewater catalyzed by metal ion supported on cation exchange resin in suspended bed electrolytic reactor with graphite electrode has been investigated. The catalyst was characterized by SEM and XPS spectra and the effects of pH, the different metal ion and NaCl on the efficiency of the electrochemical oxidation phenol process were also studied. It was found that the catalyst containing Fe3+ had the highest electrochemical catalytic activity for the electrochemical oxidation of phenol. When the initial concentration of phenol was 200 ppm, up to 90% chemical oxygen demand (COD) removal was obtained in 10 min. When the catalyst containing Fe3+ was used to the paper mill wastewater, it still showed high efficiency. The COD removal could get to 75% in 60 min

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-15

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

  17. Synthesis of Grafted Hydrogels as Mono-Divalent Cation Exchange and Drug Delivery

    International Nuclear Information System (INIS)

    ph-sensitive grafted poly vinyl alcohol-poly acrylic acid (PVA-PAA) hydrogels has been prepared by direct radiation grafting of acrylic acid (AA) onto PVA hydrogels. The grafting percent increase as the monomer concentration and irradiation dose increase. The maximum grafting yield was obtained at monomer concentration 50 % and irradiation dose 50 kGy. The swelling, thermogravimetric analysis, activation energy and scanning electron microscope of the grafted copolymer hydrogels were studied. The swelling of co-polymeric hydrogel was studied at different ph, and the gel demonstrate high swelling at ph 6.8. The de swelling of the swollen hydrogel in Ni2+ and Cu2+ cations solution was explained on the basis of mono-divalent cation exchange. The hydrogel was loaded by antihistaminic chlorphenamine maleate hydrochloride (CPM) as drug model. The release of (CPM) was faster in stimulated gastric fluid (SGF) of ph 1.1 than in stimulated intestinal fluid (SIF) of ph 6.8

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

    DEFF Research Database (Denmark)

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

    2004-01-01

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

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

    DEFF Research Database (Denmark)

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

    2004-01-01

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

  20. HTGR fuel development: loading of uranium on carboxylic acid cation-exchange resins using solvent extraction of nitrate

    International Nuclear Information System (INIS)

    The reference fuel kernel for recycle of 233U to HTGR's (High-Temperature Gas-Cooled Reactors) is prepared by loading carboxylic acid cation-exchange resins with uranium and carbonizing at controlled conditions. The purified 233UO2(NO3)2 solution from a fuel reprocessing plant contains excess HNO3 (NO3-/U ratio of approximately 2.2). The reference flowsheet for a 233U recycle fuel facility at Oak Ridge uses solvent extraction of nitrate by a 0.3 M secondary amine in a hydrocarbon diluent to prepare acid-deficient uranyl nitrate. This nitrate extraction, along with resin loading and amine regeneration steps, was demonstrated in 14 runs. No significant operating difficulties were encountered. The process is controlled via in-line pH measurements for the acid-deficient uranyl nitrate solutions. Information was developed on pH values for uranyl nitrate solution vs NO3-/U mole ratios, resin loading kinetics, resin drying requirements, and other resin loading process parameters. Calculations made to estimate the capacities of equipment that is geometrically safe with respect to control of nuclear criticality indicate 100 kg/day or more of uranium for single nitrate extraction lines with one continuous resin loading contactor or four batch loading contactors. (auth)

  1. Quantification of unsaturated-zone alteration and cation exchange in zeolitized tuffs at Yucca Mountain, Nevada, USA

    Science.gov (United States)

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

    2001-10-01

    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

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

    International Nuclear Information System (INIS)

    Density-functional theory calculations including a semi-empirical dispersion correction (DFT-D) are employed to study the interaction of small guest molecules (CH4, CO, N2) with the cation sites in the silicoaluminophosphate SAPO-34. Eight different cations from three different groups (alkali cations, alkaline earth cations, transition metals) are included in the study. For each case, the total interaction energy as well as the non-dispersive contribution to the interaction are analysed. Electron density difference plots are used to investigate the nature of this non-dispersive contribution in more detail. Despite a non-negligible contribution of polarisation interactions, the total interaction remains moderate in systems containing main group cations. In SAPOs exchanged with transition metals, orbital interactions between the cations and CO and N2 lead to a very strong interaction, which makes these systems attractive as adsorbents for the selective adsorption of these species. A critical comparison with experimental heats of adsorption shows reasonable quantitative agreement for CO and N2, but a pronounced overestimation of the interaction strength for methane. While this does not affect the conclusions regarding the suitability of TM-exchanged SAPO-34 materials for gas separations, more elaborate computational approaches may be needed to improve the quantitative accuracy for this guest molecule.

  3. Cation-exchanger fabric prepared by electron beam - induced graft copolymerization of binary monomer mixture

    International Nuclear Information System (INIS)

    Applying the electron-beam preirradiation method in air the sorption-active polypropylene fiber, containing sulfonic acid (R-SO3H) groups, was prepared by simultaneous graft copolymerization of sodium styrenesulfonate with acrylic acid in water solution. The effect of reaction conditions on the grafting yield and reaction mechanism was examined. It was found that the received CEF contains groups of strong acid (R-SO3H) and weak acid (R-COOH) in almost equal proportion. The ion-exchange properties of the CEF towards Cu(II) and Co(II) ions were investigated depending on the form of the CEF and a pH of the solution. It was shown that the utilization of the CEF in Na- form allows to make the best use of its ion-exchange capacity. (author)

  4. Copper removal and nickel for exchange cationic with a natural zeolite

    International Nuclear Information System (INIS)

    Natural zeolite clinoptilolite, was used to remove copper and nickel from waste waters of a galvanotechnical company. Exchange capacity determined for the zeolite after its transformation to homoionic sodium form, was 0.794 meq/g for copper and 0.447 meq/g for nickel. There were made batch and column experiments, reaching the last one a better approach to the equilibrium. From the degeneration essays, the sodical zeolite concentrates the copper in the waste waters to 23.5 up times the level found for the acid rinsing waters; it shows its potential use in treatment of these waste, because its effectiveness and low cost

  5. Identification of a crucial histidine involved in metal transport activity in the Arabidopsis cation/H(+) exchanger CAX1

    Science.gov (United States)

    In plants, yeast and bacteria, cation/H(+) exchangers (CAXs), have been shown to translocate Ca(2+) and other metals. The best characterized of these related transporters is the plant vacuolar-localized CAX1. We used site-directed mutagenesis to assess the impact of altering the seven histidine re...

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

    Institute of Scientific and Technical Information of China (English)

    GAODabin

    1992-01-01

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

  7. Bandgap tunable colloidal Cu-based ternary and quaternary chalcogenide nanosheets via partial cation exchange

    Science.gov (United States)

    Ramasamy, Parthiban; Kim, Miri; Ra, Hyun-Soo; Kim, Jinkwon; Lee, Jong-Soo

    2016-04-01

    Copper based ternary and quaternary semiconductor nanostructures are of great interest for the fabrication of low cost photovoltaics. Although well-developed syntheses are available for zero dimensional (0D) nanoparticles, colloidal synthesis of two dimensional (2D) nanosheets remains a big challenge. Here we report, for the first time, a simple and reproducible cation exchange approach for 2D colloidal Cu2GeSe3, Cu2ZnGeSe4 and their alloyed Cu2GeSxSe3-x, Cu2ZnGeSxSe4-x nanosheets using pre-synthesized Cu2xSe nanosheets as a template. A mechanism for the formation of Cu2-xSe nanosheets has been studied in detail. In situ oxidation of Cu+ ions to form a CuSe secondary phase facilitates the formation of Cu2-xSe NSs. The obtained ternary and quaternary nanosheets have average lateral size in micrometers and thickness less than 5 nm. This method is general and can be extended to produce other important ternary semiconductor nanosheets such as CuIn1-xGaxSe2. The optical band gap of these nanosheets is tuned from 1 to 1.48 eV, depending on their composition.Copper based ternary and quaternary semiconductor nanostructures are of great interest for the fabrication of low cost photovoltaics. Although well-developed syntheses are available for zero dimensional (0D) nanoparticles, colloidal synthesis of two dimensional (2D) nanosheets remains a big challenge. Here we report, for the first time, a simple and reproducible cation exchange approach for 2D colloidal Cu2GeSe3, Cu2ZnGeSe4 and their alloyed Cu2GeSxSe3-x, Cu2ZnGeSxSe4-x nanosheets using pre-synthesized Cu2xSe nanosheets as a template. A mechanism for the formation of Cu2-xSe nanosheets has been studied in detail. In situ oxidation of Cu+ ions to form a CuSe secondary phase facilitates the formation of Cu2-xSe NSs. The obtained ternary and quaternary nanosheets have average lateral size in micrometers and thickness less than 5 nm. This method is general and can be extended to produce other important ternary

  8. Lessons learned from the Febex in situ test: modifications at cation exchange positions by effect of a thermo-hydraulic gradient and the bentonite pore water

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Compacted bentonites are considered as a backfill and sealing material in most high-level radioactive waste disposal (HLW) concepts because of its physico-chemical properties. One of these properties arises from the electrical charge on the clay mineral surfaces, which affects the bentonite capacity for interacting with water and solutes. The total electrical charge distribution in clay particles is centred in two surface functional groups that give rise to different reactivities: a) aluminol and silanol edge surface hydroxyl groups, where the surface complexation processes occur; and 2) siloxane di-trigonal cavities or siloxane surfaces, where the exchange reactions take place. The excess of negative charge (CEC parameter) has important repercussions in degree of swelling, hydration, rheological properties, acid/base properties and adsorption/retention of cations in clays. In the last years, the accurate determination of the CEC and the concentration of cations at exchange positions have been one of the main problems tackled, and a lot of procedures and methods are found in the literature. This is because the CEC depends on the measurement conditions: pH, ionic strength, solid to liquid ratio, temperature and dielectric constant of the medium. The standard method by using NH4OAC 1 M at pH 7 and 25 C has a lot of drawbacks. For this reason, there are other methods based on: a) extracting solutions at pH 8.2 for limiting the dissolution of carbonates; b) organic solvents less polar than water limiting dissolution of sulfates also; and c) solutions with cations of high affinity (Cs, Co(NO3)63+ or Ag-Thiourea saturated in calcite). In the FEBEX project, different methods were used for analysing the CEC and cation concentration at exchange sites in different laboratory tests. These include tests with bentonite at as received or natural conditions and bentonite subjected to heating and hydration in thermo

  9. Avaliação da capacidade de troca de cátions em solos utilizando o método do tampão SMP Evaluation of the cation exchange capacity of soils utilizing the SMP buffer method

    OpenAIRE

    Otávio Antonio de Camargo; Bernardo Van Raij; José Maria Aires da Silva Valadares

    1982-01-01

    Foram feitas as determinações da capacidade de troca de cations (CTC) em amostras de solos pelos métodos do acetato de cálcio IN pH 7,0; acetato de amônio IN pH 7,0, e cloreto de bário tamponado com trietanolamina pH 8,2, sendo os resultados comparados com os obtidos utilizando o método do tampão SMP para determinar (H + Al) mais a soma de bases, rotineiramente obtida em laboratório. As correlações entre os resultados de (H + Al), CTC e porcentagens de saturação em bases obtidas pelos diferen...

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

    Indian Academy of Sciences (India)

    Amin Jignasa; Thakkar Rakesh; Chudasama Uma

    2006-03-01

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

  11. 1H and 23Na MAS NMR spectroscopy of cationic species in CO2 selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    Science.gov (United States)

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

    2012-07-01

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

  12. Sorption of (226)Ra from oil effluents onto synthetic cation exchangers.

    Science.gov (United States)

    Al Attar, Lina; Safia, Bassam

    2013-07-30

    Increasing environmental awareness is being urged for the safe disposal of (226)Ra-contaminated production water generated in the oil industry. Birnessite, antimony silicate and their cationic derivatives were studied for the take-up of (226)Ra using the batch-type method under experimentally determined parameters, viz. contact time, solution-solid ratio and (226)Ra concentration. Data was expressed in terms of distribution coefficients. Sorption experiments were performed in different concentrations of nitric acid in order to speculate the mechanism of (226)Ra uptake. Variation in the magnitude of sorption efficiency of the materials in the presence of the major components of waste streams, i.e. Na(+), K(+) and Ca(2+), revealed that K(+) was the greatest competitor and Na(+) the least. The application of the materials to sorb (226)Ra from actual oil co-production water samples, collected from Der Ezzor and Al Fourat petroleum companies (DEZPC and AFPC), was interpreted in terms of the exchange properties of the materials and water characterisation. Of the parameters studied, the selectivity of materials was shown to be greatly dependent on the pH of wastewater to be treated. PMID:23623032

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

    Institute of Scientific and Technical Information of China (English)

    LIGUI-BAO; J.J.SCHOENAU; 等

    1995-01-01

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

  14. Effects of Experimental Conditions on Extraction Yield of Extracellular Polymeric Substances by Cation Exchange Resin

    Directory of Open Access Journals (Sweden)

    Jinwoo Cho

    2012-01-01

    Full Text Available Effects of experimental conditions on the yield of extracellular polymeric substances (EPSs extraction by cation exchange resin (CER were investigated using activated sludge flocs. The experimental variables included resin dose, extraction time, sample dilution, and storage time. An empirical model was proposed to describe the kinetics of extraction process. The extraction yield increases with the extraction time and CER dose until it reached the maximum amount of EPS extraction. The maximum yield of EPS was affected as well by the sample dilution, exhibiting a decreasing trend with increasing dilution factor. It was also found that the amount of EPS extracted from a raw sample depends on the storage time. Once EPS was extracted from the sample, however, the EPS keeps its original quantity under storage at 4°C. Based on the model, the maximum amount of EPS extraction and yield rate could be estimated for different conditions. Comparing the model parameters allows one to quantitatively compare the extraction efficiencies under various extracting conditions. Based on the results, we recommend the original sample should be diluted with the volume ratio of above 1 : 2 and a raw sample should be treated quickly to prevent the reduction of sample homogeneity and original integrity.

  15. Cation exchange resin immobilized bimetallic nickel-iron nanoparticles to facilitate their application in pollutants degradation.

    Science.gov (United States)

    Ni, Shou-Qing; Yang, Ning

    2014-04-15

    Nanoscale zerovalent iron (nZVI) usually suffers from reduction of reactivity by aggregation, difficulty of assembling, environmental release and health concerns. Furthermore, data are lacking on the effect of cheap nickel on debromination of decabromodiphenyl ether (DBDE) by immobilized nZVI in aqueous system. In this study, strong acid polystyrene cation-exchange resins with particle diameter from 0.4 to 0.6 mm were utilized as matrices to immobilize bimetallic nickel-iron nanoparticles in order to minimize aggregation and environmental leakage risks of nZVI and to enhance their reactivity. Elemental distribution mapping showed that iron particles distributed uniformly on the surface of the resin and nickel particles were dispersed homogeneously into Fe phase. The reaction rate of resin-bound nZVI is about 55% higher than that of dispersed nZVI. The immobilized bimetallic nanoparticles with 9.69% Ni had the highest debromination percent (96%) and reaction rate (0.493 1/h). The existence of Ni significantly improved the debromination rate, due to the surface coverage of catalytic metal on the reductive metal and the formation of a galvanic cell. The environmental dominant congeners, such as BDE 154, 153, 100, 99 and 47, were produced during the process. Outstanding reactive performance, along with magnetic separation assured that resin-bound bimetallic nickel-iron nanoparticles are promising material that can be utilized to remediate a wide variety of pollutants contaminated sites including polybrominated diphenyl ethers. PMID:24559714

  16. Effects of experimental conditions on extraction yield of extracellular polymeric substances by cation exchange resin.

    Science.gov (United States)

    Cho, Jinwoo; Hermanowicz, Slawomir W; Hur, Jin

    2012-01-01

    Effects of experimental conditions on the yield of extracellular polymeric substances (EPSs) extraction by cation exchange resin (CER) were investigated using activated sludge flocs. The experimental variables included resin dose, extraction time, sample dilution, and storage time. An empirical model was proposed to describe the kinetics of extraction process. The extraction yield increases with the extraction time and CER dose until it reached the maximum amount of EPS extraction. The maximum yield of EPS was affected as well by the sample dilution, exhibiting a decreasing trend with increasing dilution factor. It was also found that the amount of EPS extracted from a raw sample depends on the storage time. Once EPS was extracted from the sample, however, the EPS keeps its original quantity under storage at 4°C. Based on the model, the maximum amount of EPS extraction and yield rate could be estimated for different conditions. Comparing the model parameters allows one to quantitatively compare the extraction efficiencies under various extracting conditions. Based on the results, we recommend the original sample should be diluted with the volume ratio of above 1:2 and a raw sample should be treated quickly to prevent the reduction of sample homogeneity and original integrity. PMID:22919352

  17. Adsorption equilibrium and kinetics of monomer-dimer monoclonal antibody mixtures on a cation exchange resin.

    Science.gov (United States)

    Reck, Jason M; Pabst, Timothy M; Hunter, Alan K; Wang, Xiangyang; Carta, Giorgio

    2015-07-10

    Adsorption equilibrium and kinetics are determined for a monoclonal antibody (mAb) monomer and dimer species, individually and in mixtures, on a macroporous cation exchange resin both under the dilute limit of salt gradient elution chromatography and at high protein loads and low salt based on batch adsorption equilibrium and confocal laser scanning microscopy (CLSM) experiments. In the dilute limit and weak binding conditions, the dimer/monomer selectivity in 10mM phosphate at pH 7 varies between 8.7 and 2.3 decreasing with salt concentration in the range of 170-230mM NaCl. At high protein loads and strong binding conditions (0-60mM NaCl), the selectivity in the same buffer is near unity with no NaCl added, but increases gradually with salt concentration reaching high values between 2 and 15 with 60mM added NaCl. For these conditions, the two-component adsorption kinetics is controlled by pore diffusion and is predicted approximately by a dual shrinking core model using parameters based on single component equilibrium and kinetics measurements. PMID:26028510

  18. Relative activities of siloxane monomers toward the cation exchange resin-catalyst in the equilibration reactions

    Directory of Open Access Journals (Sweden)

    M. N. GOVEDARICA

    2001-07-01

    Full Text Available The relative activities of a number of siloxane monomers, both cyclic and linear, toward the cation exchange resin-equilibration catalyst were determined. The determination was based on the fact that when a particular siloxane compound is added to an arbitrarily chosen equilibrate, it takes part in the equilibration process, provoking certain viscosity changes of the reaction mixture. Taking these viscosity changes as a measure of activities, the following order was obtained: hexamethylcyclotrisiloxane > hexamethyldisiloxane > octamethylcyclotetrasiloxane > one linear all-methyl oligosiloxane of number average molecular weight of approximately 800 > decamethylcyclopentasiloxane. The results obtained by using the described viscosimetrical determination method were controlled by measuring the number average molecular weights of the reaction mixtures at the beginning and at the end of the equilibration process. The deviations of the experimentally measured from the calculated values were less than 20 %, as was found in one equilibration system. In most other systems the deviations were about 10 % which is a very good result which strengthens the validity of the applied determination method.

  19. A study on Sn4+ cation exchange natural zeolite treated at different temperatures

    International Nuclear Information System (INIS)

    The samples of Sn4+ zeolite are obtained by cation exchange between natural zeolite and SnCl4, and then treated at different temperatures (70 -1000 deg C). By using Moessbauer spectroscopy, X-ray diffraction and infra-red spectroscopy, the change of position of Sn4+ in the zeolite structure with the temperature is studied. The results show that the Sn4+ is situated in the main duct (channel) of the zeolite structure, but with the increase of the temperature the zeolite is dehydrated gradually, then the Sn4+ begins to move from the center of the duct to the walls of the duct, consequently, owing to the increase of the asymmetry of the electric field where the Sn4+ is situated, the quadruple splitting increase with the increase of the temperature. At the same time the SnO2 component increases with the increase of temperature. When heat-treatment temperature reached 1000 deg C the long range order structure of zeolite may be destroyed completely

  20. Chemical and dimensional evolution of cationic ions exchange resins in cement pastes

    International Nuclear Information System (INIS)

    Ion exchange resins (IERs) are widely used by the nuclear industry to decontaminate radioactive effluents. After use they are usually encapsulated in cementitious materials. However, the solidified waste forms can exhibit a strong expansion, possibly leading to cracking. Its origin is not well understood as well as the conditions when it occurs.In this work, the interactions between cationic resins in the Na+ or Ca2+ form and tricalcium silicate (C3S), Portland cement (CEM I) or Blast furnace slag cement (CEM III/C) are investigated at an early age in order to gain a better understanding of the expansion process.The results show that during the hydration of a paste of C3S or CEM I containing IERs in the Na+ form, the resins exhibit a transient expansion of small magnitude due to the decrease in the osmotic pressure of the interstitial solution. This expansion, which occurs just after cement setting, is sufficient to damage the material which is poorly consolidated for several reasons: small hydration degree, precipitation of less cohesive sodium bearing C-S-H, heterogeneous microstructure with highly porous zones and lastly cleavable crystals of portlandite at the interface between resins and paste. This expansion can be prevented by performing a calcium pretreatment of the resins or by using a CEM III/C cement with a slower rate of hydration than that of Portland cement. (author)

  1. chromatographic studies for separation of light lanthanides using Dowex-50X8 cation exchanger

    International Nuclear Information System (INIS)

    chromatographic elution of light lanthanides (La, Ce, Nd and Sm) using the strong cation exchange resin, Dowex-50X8 has been investigated through certain elution parameters. elution profiles of La, Ce, Nd and Sm were studied with three different mobile phases: oxalic acid, citric acid and sodium hexameta phosphate. considering % recovered, sodium hexameta phosphate showed the highest values with all investigated elements but it has some disadvantages like tailing, low separation and resolution values that indicating a poor separation pattern and long elution time. on other side citric acid showed many advantages as an eluent over the other eluents, where it has narrow and symmetrical elution peaks compared to those of the other eluents. increasing citric acid concentration , it was observed that the separation factor decreased although the % recovered increased. from ph 3.5-6.5 the retention volumes of the investigated ions decreased drastically, indicating that the separation factor between each neighboring element also decreased . it was also observed that, the distribution coefficient not affected by changing the flow rate from 1 to 10 ml/min. for easy detection and identification , the ion chromatography technique was used.

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

    Directory of Open Access Journals (Sweden)

    Khan S

    2007-01-01

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

  3. Experimental Characterization and Modelization of Ion Exchange Kinetics for a Carboxylic Resin in Infinite Solution Volume Conditions. Application to Monovalent-Trivalent Cations Exchange

    International Nuclear Information System (INIS)

    This study is devoted to the characterization of ion exchange inside a microsphere of carboxylic resin. It aims at describing the kinetics of this exchange reaction which is known to be controlled by interdiffusion in the particle. The fractional attainment of equilibrium function of time depends on the concentration of the cations in the resin which can be modelled by the Nernst-Planck equation. A powerful approach for the numerical resolution of this equation is introduced in this paper. This modeling is based on the work of Helfferich but involves an implicit numerical scheme which reduces the computational cost. Knowing the diffusion coefficients of the cations in the resin and the radius of the spherical exchanger, the kinetics can be hence completely determined. When those diffusion parameters are missing, they can be deduced by fitting experimental data of fractional attainment of equilibrium. An efficient optimization tool coupled with the implicit resolution has been developed for this purpose. A monovalent/trivalent cation exchange had been experimentally characterized for a carboxylic resin. Diffusion coefficients and concentration profiles in the resin were then deduced through this new model. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-15

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

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

    Science.gov (United States)

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

    2004-06-11

    The determination of seven aliphatic carboxylic acids, formic, acetic, propionic, isobutyric, n-butyric, isovaleric and n-valeric acids in anaerobic digestion process waters was examined using ion-exclusion chromatography with conductimetric detection. The analysis of these biologically important carboxylic acids is necessary as a measure for evaluating and controlling the process. The ion-exclusion chromatography system employed consisted of polymethacrylate-based weakly acidic cation-exchange resin columns (TSKgel OApak-A or TSKgel Super IC-A/C). weakly acidic eluent (benzoic acid), and conductimetric detection. Particle size and cation-exchange capacity were 5 microm and 0.1 meq./ml for TSKgel OApak-A and 3 microm and 0.2 meq./ml for TSKgel Super IC-A/C, respectively. A dilute eluent (1.0-2.0 mM) of benzoic acid was effective for the high resolution and highly conductimetric detection of the carboxylic acids. The good separation of isobutyric and n-butyric acids was performed using the TSKgel Super IC-A/C column (150 mm x 6.0 mm i.d. x 2). The simple and good chromatograms were obtained by the optimized ion-exclusion chromatography conditions for real samples from mesophilic anaerobic digestors, thus the aliphatic carboxylic acids were successfully determined without any interferences. PMID:15250416

  6. Modeling the competition between solid solution formation and cation exchange on the retardation of aqueous radium in an idealized bentonite column

    International Nuclear Information System (INIS)

    Clays and clay rocks are considered viable geotechnical barriers in radioactive waste disposal. One reason for this is the propensity for cation exchange reactions in clay minerals to retard the migration of radionuclides. Although another retardation mechanism, namely the incorporation of radionuclides into sulfate or carbonate solid solutions, has been known for a long time, only recently has it been examined systematically. In this work, we investigate the competitive effect of both mechanisms on the transport of radium (Ra) in the near-field of a low- and intermediate level nuclear waste repository. In our idealized geochemical model, numerical simulations show that barium (Ba) and strontium (Sr) needed for Ra sulfate solid solutions also partition to the cation exchange sites of montmorillonite (Mont), which is the major mineral constituent of bentonite that is used for tunnel backfill. At high Mont content, most Ra tends to attach to Mont, while incorporation of Ra in sulfate solid solutions is more important at low Monte content. To explore the effect of the Mont content on the transport of radium, a multi-component reactive transport model was developed and implemented in the scientific software OpenGeoSys-GEM. It was found that a decrease of fixation capacity due to low Mont content is compensated by the formation of solid solutions and that the migration distance of aqueous Ra is similar at different Mont/water ratios. (author)

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

    International Nuclear Information System (INIS)

    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 ·O2− 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 (·O2−) 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

  8. A cation exchange model to describe Cs + sorption at high ionic strength in subsurface sediments at Hanford site, USA

    Science.gov (United States)

    Liu, Chongxuan; Zachara, John M.; Smith, Steve C.

    2004-02-01

    A theoretical and experimental study of cation exchange in high ionic strength electrolytes was performed using pristine subsurface sediments from the U.S. Department of Energy Hanford site. These sediments are representative of the site contaminated sediments impacted by release of high level waste (HLW) solutions containing 137Cs + in NaNO 3 brine. The binary exchange behavior of Cs +-Na +, Cs +-K +, and Na +-K + was measured over a range in electrolyte concentration. Vanselow selectivity coefficients ( Kv) that were calculated from the experimental data using Pitzer model ion activity corrections for aqueous species showed monotonic increases with increasing electrolyte concentrations. The influence of electrolyte concentration was greater on the exchange of Na +-Cs + than K +-Cs +, an observation consistent with the differences in ion hydration energy of the exchanging cations. A previously developed two-site ion exchange model [Geochimica et Cosmochimica Acta 66 (2002) 193] was modified to include solvent (water) activity changes in the exchanger phase through application of the Gibbs-Duhem equation. This water activity-corrected model well described the ionic strength effect on binary Cs + exchange, and was extended to the ternary exchange system of Cs +-Na +-K + on the pristine sediment. The model was also used to predict 137Cs + distribution between sediment and aqueous phase ( Kd) beneath a leaked HLW tank in Hanfordd's S-SX tank using the analytical aqueous data from the field and the binary ion exchange coefficients for the pristine sediment. The Kd predictions closely followed the trend in the field data and were improved by consideration of water activity effects that were considerable in certain regions of the vadose zone plume.

  9. 1H and 23Na MAS NMR spectroscopy of cationic species in CO2 selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    International Nuclear Information System (INIS)

    The location of extraframework cations in Sr2+ and Ba2+ ion-exchanged SAPO-34 was estimated by means of 1H and 23Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO2 adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium. - Graphical abstract: MAS NMR was used to elucidate the position the cationic species in alkaline earth metal exchanged silicoaluminophosphates. These species played a significant role during the ion exchange process and, therefore, the materials ultimate CO2 adsorption performance. Highlights: ► Location of extraframework Sr2+ or Ba2+ cations was estimated by means of 1H and 23Na MAS NMR. ► Level of Sr2+ or Ba2+ ion exchange was limited by the presence of protons and sodium cations. ► Presence of ammonium cations in the supercages facilitated the exchange. ► Sr2+ and Ba2+ ion exchanged SAPOs are outstanding CO2 adsorbents.

  10. A comparative study on textural characterization: cation-exchange and sorption properties of crystalline alpha-zirconium(IV), tin(IV), and titanium(IV) phosphates.

    Science.gov (United States)

    Parida, K M; Sahu, B B; Das, D P

    2004-02-15

    Tetravalent metal phosphates (M=Zr, Ti, and Sn) were prepared and characterized by XRD, surface properties, and TG-DTA. The cation exchange and sorption behavior of these metal phosphates toward transition metal ions such as Cu(2+), Co(2+), and Ni(2+) have been studied comparatively as a function of temperature and concentration. The adsorption process was found to increases with increase in temperature and concentration. The selectivity order for alpha-titanium and alpha-tin phosphates is Cu(2+)>Co(2+)>Ni(2+), whereas for alpha-zirconium phosphate it is Cu(2+)>Ni(2+)>Co(2+). The ion exchange capacity of alpha-titanium phosphate is greater than those of other phosphates, which is explained on the basis of the surface behavior, disorderness of the system, degree of hydrolysis of incoming guest adsorbate metal ions, and structural steric hindrance of the exchangers during adsorption and sorption. The distribution coefficient, Gibbs free energy, enthalpy, and entropy values indicate that the ion-exchange processes are spontaneous. PMID:14697711

  11. Cation exchanged Fe(II) and Sr compared to other divalent cations (Ca, Mg) in the bure Callovian-Oxfordian formation: Implications for porewater composition modelling

    International Nuclear Information System (INIS)

    Iron and Sr bearing phases were thoroughly investigated by means of spectrometric and microscopic techniques in Callovian-Oxfordian (COX) samples originating from the ANDRA Underground Research Laboratory (URL) in Bure (France). Strontium was found to be essentially associated with celestite, whereas Fe was found to be distributed over a wide range of mineral phases. Iron was mainly present as Fe(II) in the studied samples (∼93% from Moessbauer results). Most of the Fe(II) was found to be in pyrite, sideroplesite/ankerite and clay minerals. Iron(III), if present, was associated with clay minerals (probably illite, illite-smectite mixed layer minerals and chlorite). No Fe(III) oxy(hydro)xide could be detected in the samples. Strontianite was not observed either. Based on these observations, it is likely that the COX porewater is in equilibrium with the following carbonate minerals, calcite, dolomite and ankerite/sideroplesite, but not with strontianite. It is shown that this equilibrium information can be combined with clay cation exchange composition information in order to give direct estimates or constraints on the solubility products of the carbonate minerals dolomite, siderite and strontianite. As a consequence, an experimental method was developed to retrieve the cation exchanged Fe(II) in very well preserved COX samples. The very homogeneous cation exchange composition of the formation is completely in agreement with a homogeneous presence of calcite and dolomite minerals whose equilibrium reactions control part of the porewater composition. Amongst the broad range of values available for dolomite solubility products in thermodynamic databases, the value of log Kdolomite = -3.57 is the most appropriate for the one present in the COX formation. With regard to strontianite, it appears that the equilibrium constant tabulated in the Llnl database is not valid for natural clay systems. The value given by Busenberg et al. used by most of the other available

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

    OpenAIRE

    Storm, Ida Drejer; Have Rasmussen, Peter; Strobel, Bjarne W.; Hansen, Hans Christian Bruun

    2008-01-01

    Abstract Ergot alkaloids (EAs) are mycotoxins which are unavoidable contaminants of cereal products, particularly rye. A method was compiled employing clean-up by cation-exchange solid phase extraction, separation by high-pressure liquid chromatography under alkaline conditions and fluorescence detection. It is capable of separating and quantifying both C8-isomers of ergocornine, a-ergocryptine, ergocristine, ergonovine, and ergotamine. The average recovery was 61?10 % with limits ...

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

    DEFF Research Database (Denmark)

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

    2004-01-01

    Different routes were screened for the preparation of superparamagnetic cation-exchange adsorbents for the capture of proteins using high-gradient magnetic fishing. Starting from a polyglutaraldehyde-coated base particle, the most successful of these involved attachment of sulphite to oligomers of...... 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...

  14. Preparation of decarboxylic-functionalized weak cation exchanger and application for simultaneous separation of alkali, alkaline earth and transition metals.

    Science.gov (United States)

    Peng, Yahui; Gan, Yihui; He, Chengxia; Yang, Bingcheng; Guo, Zhimou; Liang, Xinmiao

    2016-06-01

    A novel weak cation exchanger (WCX) with dicarboxyl groups functionalized has been developed by clicking mercaptosuccinic acid onto silica gel. The simple synthesis starts with modification of silica gel with triethoxyvinylsilane, followed by efficient coupling vinyl-bonded silica with mercaptosuccinic acid via a "thiol-ene" click reaction. The obtained WCX demonstrated good separation and high selectivity towards common metals. Simultaneous separation of 10 alkali, alkaline earth and transition metals was achieved within 12min. Ion exchange and complex mechanism dominates the separation process. Its utility was demonstrated for determination of metals in tap water. PMID:27130093

  15. Enhanced Transport of U(Vi) and Th(IV) Through Cation Exchange Membrane Using Electric Field

    International Nuclear Information System (INIS)

    Transport of ionic species through ion exchange membrane found several applications for water effluents purification and metal ion separation. To enhance the transport performance, the effect of electric field was introduced in this work. The transport of U (Vi) and Th(IV) species in nitric acid solutions across cation exchange membrane was investigated. In this concern, different parameters affecting the transport were studied. These parameters include; nitric acid concentration in the feed solution, stripping solution concentration and applied electric field. From the results obtained the permeability coefficient of U(Vi) and Th(IV) were calculated. Based on these information, a process for separation of thorium from uranium is developed

  16. Optimization of acidified oil esterification catalyzed by sulfonated cation exchange resin using response surface methodology

    International Nuclear Information System (INIS)

    Highlights: • As lipid source, acidified oil are from industrial wastes for renewable energy. • The predicted conversion rate of FFAs was 75.24% under the RSM optimized conditions. • The adsorption system was employed to remove the water produced to shift the equilibrium toward ethyl ester production. • Maximum conversion rate of 98.32% was obtained using adsorption system at optimum process parameters. • Compared with tradition methods, molecular sieve dehydration method improved the conversion rate by 23.08%. - Abstract: The esterification of acidified oil with ethanol catalyzed by sulfonated cation exchange resins (SCER) was optimized using the response surface methodology (RSM). The effects of the molar ratio of ethanol to acidified oil, reaction time and catalyst loading on the conversion rate of free fatty acids (FFAs) were investigated at the temperature of the boiling point of ethanol. Results showed that the highest conversion rate of 75.24% was obtained at the molar ratio of ethanol to acidified oil of 23.2, reaction time of 8.0 h and catalyst loading of 35.0 wt.%. Moreover, the conversion rate of FFAs was increased to 98.32% by using a water adsorption apparatus under the RSM optimized conditions. Scanning electronic microscopic–energy dispersive spectrometric (SEM–EDS), X-ray diffractometric (XRD) and thermogravimetric–derivative thermogravimetric (TG–DTG) analyses confirmed that the morphology of catalysts did not change much and the mechanical and thermal stabilities were still good after the reaction. Furthermore, SCER exhibited a high catalytic activity and stability after being reused for five successive times. The fuel properties of the biodiesel were comparable to that of ASTM, EN and GB biodiesel standard

  17. Separation of proteins by cation-exchange sequential injection chromatography using a polymeric monolithic column.

    Science.gov (United States)

    Masini, Jorge Cesar

    2016-02-01

    Since sequential injection chromatography (SIC) emerged in 2003, it has been used for separation of small molecules in diverse samples, but separations of high molar mass compounds such as proteins have not yet been described. In the present work a poly(glycidyl methacrylate-co-ethylene dimethacrylate) (GMA-co-EDMA) monolithic column was prepared by free radical polymerization inside a 2.1-mm-i.d. activated fused silica-lined stainless steel tubing and modified with iminodiacetic acid (IDA). The column was prepared from a mixture of 24% GMA, 16% EDMA, 20% cyclohexanol, and 40% 1-dodecanol (all% as w/w) containing 1% of azobisisobutyronitrile (AIBN) (in relation to monomers). Polymerization was done at 60 °C for 24 h. The polymer was modified with 1.0 M IDA (in 2 M Na2CO3, pH 10.5) at 80 °C for 16 h. Separation of myoglobin, ribonuclease A, cytochrome C, and lysozyme was achieved at pH 7.0 (20 mM KH2PO4/K2HPO4) using a salt gradient (NaCl). Myoglobin was not retained, and the other proteins were separated by a gradient of NaCl created inside the holding coil (4 m of 0.8-mm-i.d. PTFE tubing) by sequential aspiration of 750 and 700 μL of 0.2 and 0.1 M NaCl, respectively. As the flow was reversed toward the column (5 μL s(-1)) the interdispersion of these solutions created a reproducible gradient which separated the proteins in 10 min, with the following order of retention: ribonuclease A < cytochrome C < lysozyme. The elution order was consistent with a cation-exchange mechanism as the retention increased with the isoelectric points. PMID:26677024

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

    Science.gov (United States)

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

    2013-03-01

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

  19. Cation exchange resins labeled with holmium-166 for treatment of liver malignancy

    International Nuclear Information System (INIS)

    The increasing interest in new therapeutic radiopharmaceuticals is prompting investigators to utilize isotopes with more focused capabilities for treating various tumors, reducing the negative effects on neighboring healthy cells. Local radionuclide therapy using radioactive microspheres is a promising therapy for non-operable group of patients suffering from liver malignancies. Many publications have shown the success of this technique. The emphasis in the present work is the resin-based microspheres labeled with 166Ho. The production of 166Ho is feasible in the IEA-R1 Reactor at IPEN-CNEN/SP, because it does not need high power and high neutron fluxes. Samples of Ho2O3 were irradiated in selected positions of the nuclear reactor IEA-R1 at IPEN/CNEN-SP. The neutron flux was 1.0 x1013 n.s-1.cm-2 for 1 hour. The dissolution of Ho2O3 was studied with different volumes of 0.1M HCl and also varying the heating temperature. The AG50W-X8 200-400 mesh and CM Sephadex C-25 cation exchange resins were labeled with 166Ho. The retention of 166Ho in the resins was studied and also its stability. The results of the dissolution experiments of Ho2O3 showed that there is a direct relation between the increasing volumes needed to dissolve higher masses, and also the positive effect of raising the temperature. The results show very good retention of 166Ho in both columns, even when high volumes of 0.1M HCl are passed through the column containing the resins and its good stability towards saline solution, PBS solution and glucose.Although the resins employed in this work did not have the right particle size (20-50μm), the chemical behavior showed the very good labeling of the resins with 166Ho, and its stability. (author)

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

    Institute of Scientific and Technical Information of China (English)

    LI Zhenhua; PI Hongqiong; HE Binglin

    2001-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-15

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

  2. chemical studies and sorption behavior of some hazardous metal ions on polyacrylamide stannic (IV) molybdophosphate as 'organic - inorganic' composite cation - exchanger

    International Nuclear Information System (INIS)

    compsite materials formed by the combination of multivalent metal acid salts and organic polymers provide a new class of (organic-inorganic) hypride ion exchangers with better mechanical and granulometric properties, good ion-exchange capacity, higher chemical and radiation stabilites, reproducibility and selectivity for heavy metals. this material was characterized using X-ray (XRD and XRF), IR, TGA-DTA and total elemental analysis studies. on the basis of distribution studies, the material has been found to be highly selective for pb(II). thermodynamic parameters (i.e δG0, δ S0 and δH0) have also been calculated for the adsorption of Pb2+, Cs+, Fe3+, Cd2+, Cu+2, Zn2+, Co2+ and Eu3+ions on polyacrylamide Sn(IV) molybdophosphate showing that the overall adsorption process is spontaneous endothermic. the mechanism of diffusion of Fe3+, Co2+, Cu+2, Zn2+, Cd2+, Cs+, Pb2+ and Eu3+ in the H-form of polyacrylamide Sn(IV) molybdophosphate composite as cation exchanger was studied as a function of particle size, concentration of the exchanging ions, reaction temperature, dring temperature and pH. the exchange rate was controlled by particle diffusion mechanism as a limited batch techneque and is confirmed from straight lines of B versus 1/r2 polts. the values of diffusion coefficients, activation energy and entropy of activation were calculated and their significance was discussed. the data obtained have been comared with that reported for other organic and inorganic exchangers.

  3. Synthesis of Capsule-like Porous Hollow Nanonickel Cobalt Sulfides via Cation Exchange Based on the Kirkendall Effect for High-Performance Supercapacitors.

    Science.gov (United States)

    Tang, Yongfu; Chen, Shunji; Mu, Shichun; Chen, Teng; Qiao, Yuqing; Yu, Shengxue; Gao, Faming

    2016-04-20

    To construct a suitable three-dimensional structure for ionic transport on the surface of the active materials for a supercapacitor, porous hollow nickel cobalt sulfides are successfully synthesized via a facile and efficient cation-exchange reaction in a hydrothermal process involving the Kirkendall effect with γ-MnS nanorods as a sacrificial template. The formation mechanism of the hollow nickel cobalt sulfides is carefully illustrated via the tuning reaction time and reaction temperature during the cation-exchange process. Due to the ingenious porous hollow structure that offers a high surface area for electrochemical reaction and suitable paths for ionic transport, porous hollow nickel cobalt sulfide electrodes exhibit high electrochemical performance. The Ni1.77Co1.23S4 electrode delivers a high specific capacity of 224.5 mAh g(-1) at a current density of 0.25 A g(-1) and a high capacity retention of 87.0% at 10 A g(-1). An all-solid-state asymmetric supercapacitor, assembled with a Ni1.77Co1.23S4 electrode as the positive electrode and a homemade activated carbon electrode as the negative electrode (denoted as NCS//HMC), exhibits a high energy density of 42.7 Wh kg(-1) at a power density of 190.8 W kg(-1) and even 29.4 Wh kg(-1) at 3.6 kW kg(-1). The fully charged as-prepared asymmetric supercapacitor can light up a light emitting diode (LED) indicator for more than 1 h, indicating promising practical applications of the hollow nickel cobalt sulfides and the NCS//HMC asymmetric supercapacitor. PMID:27031254

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

    Science.gov (United States)

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

    2016-08-01

    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. PMID:27288092

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

    Institute of Scientific and Technical Information of China (English)

    Yan Cao; Yunxia Zhao; Fujiao Song; Qin Zhong

    2014-01-01

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

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

    KAUST Repository

    Samin, Umer A.

    2016-04-13

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

  7. P123-T Oligonucleotide Purification Strategies using a New High-Capacity Anion Exchange Resin

    OpenAIRE

    Deetz, M.; Fisher, J. R.; Gehris, A.; Maikner, J.; Kinzey, M.

    2007-01-01

    With the advent of nucleic acid silencing technologies and the need for high purity diagnostic and therapeutic oligonucleotides, there is a need for high-capacity chromatographic supports that can deliver economic purification processes. A new, 30 micron, mono-sized, polymeric resin has been recently developed that provides high resolution and high capacity for synthetic oligonucleotides. Physical properties of this new resin will be described, including particle size uniformity, ion exchange...

  8. Behavior of cationic, anionic and colloidal species of titanium, zirconium and thorium in presence of ion exchange resins

    International Nuclear Information System (INIS)

    The distribution of titanium, zirconium and thorium is aqueous and resin phases has been studied using strong cationic resin in the R-NH4 form. Solutions of the above elements in perchloric, nitric, hydrochloric and suphuric media were used. Each set of experiments was made by separately varying one of the five parameters - type of anion present, acidity of solution, temperature of percolation, age of solution and concentration of the element. It was found that, depending on the particular balance of these parameters, the elements investigated may be found in acidic solutions either as cationic, anionic or colloidal species. It is emphasized that the colloidal species of titanium, zirconium or thorium are not retained by the ion exchangers, and from this property a method for the separation and purification of the above elements has been outlined

  9. Sorption of tannin-C by soils affects soil cation exchange capacity

    Science.gov (United States)

    Some tannins, produced by plants, are able to sorb to soil, and thus influence soil organic matter and nutrient cycling. However, studies are needed that compare sorption of tannins to other related phenolic compounds, evaluate their effects across a broad range of soils, and determine if sorption ...

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

    Science.gov (United States)

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

    2016-05-15

    Anthropogenic N deposition has been well documented to cause substantial impacts on the chemical and biological properties of forest soils. In most studies, however, atmospheric N deposition has been simulated by directly adding N to the forest floor. Such studies thus ignored the potentially significant effect of some key processes occurring in forest canopy (i.e., nitrogen retention) and may therefore have incorrectly assessed the effects of N deposition on soils. Here, we conducted an experiment that included both understory addition of N (UAN) and canopy addition of N (CAN) in two contrasting forests (temperate deciduous forest vs. subtropical evergreen forest). The goal was to determine whether the effects on soil exchangeable cations and microbial biomass differed between CAN and UAN. We found that N addition reduced pH, BS (base saturation) and exchangeable Ca and increased exchangeable Al significantly only at the temperate JGS site, and reduced the biomass of most soil microbial groups only at the subtropical SMT site. Except for soil exchangeable Mn, however, effects on soil chemical properties and soil microbial community did not significantly differ between CAN and UAN. Although biotic and abiotic soil characteristics differ significantly and the responses of both soil exchangeable cations and microbial biomass were different between the two study sites, we found no significant interactive effects between study site and N treatment approach on almost all soil properties involved in this study. In addition, N addition rate (25 vs. 50kgNha(-1)yr(-1)) did not show different effects on soil properties under both N addition approaches. These findings did not support previous prediction which expected that, by bypassing canopy effects (i.e., canopy retention and foliage fertilization), understory addition of N would overestimate the effects of N deposition on forest soil properties, at least for short time scale. PMID:26930308

  11. Determination of the ion-exchange capacity of anion-selective membranes

    Czech Academy of Sciences Publication Activity Database

    Karas, F.; Hnát, J.; Paidar, M.; Schauer, Jan; Bouzek, K.

    2014-01-01

    Roč. 39, č. 10 (2014), s. 5054-5062. ISSN 0360-3199 Institutional support: RVO:61389013 Keywords : ion-exchange capacity * anion-selective membranes * titration Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.313, year: 2014

  12. Simple cation-exchange separation for ICP-MS measurement of 79Se in spent nuclear fuel sample

    International Nuclear Information System (INIS)

    A simple separation using a single cation-exchange column has been developed for the measurement of 79Se in a spent nuclear fuel solution with inductively coupled plasma mass spectrometry (ICP-MS). An irradiated UO2 pellet cut out from a PWR fuel rod was dissolved and used as a standard sample. A known amount of 82Se (20 ng) was added to the sample solution for the determination of the amount of 79Se by isotope dilution mass spectrometry (IDMS). The 82Se-spiked and non-spiked sample solutions were fed to each cation-exchange resin-packed column, followed by 1 M nitric acid for washing. The first 3 mL of the effluent was directly injected to the ICP-MS for obtaining the isotopic ratio of 79Se/82Se. The recovery of Se in the effluent was 92%, while no leakage of Gd3+ (158Gd) and Dy3+ (164Dy) which cause major isobaric interferences on 79Se and 82Se determinations by forming 158Gd2+ and 164Dy2+, respectively, was observed. In addition, the highly radioactive coexisting components e.g., Sr2+, Y3+, Cs+, and Ba2+ were retained on the cation-exchange resin, leading to the decrease in the surface dose rate of the sample solution from 0.3 mSv/h to a background level. The isotopic ratio 82Se/79Se of the non-spiked and the spiked fractions were 5.4 ± 1.0 and 13.7 ± 2.2, respectively. From these isotopic ratios, the amounts of 79Se and 82Se in the sample solution were calculated to be 2.4 ± 0.7 and 13.3 ± 4.6 ng, respectively. (author)

  13. The elution of erbium from a cation exchanger bed by means of the N-hydroxyethyl-ethylene-diamine triacetic acid

    International Nuclear Information System (INIS)

    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

  14. Applications of Time-Resolved Synchrotron X-ray Diffraction to Cation Exchange, Crystal Growth and Biomineralization Reactions

    International Nuclear Information System (INIS)

    Advances in the design of environmental reaction cells and in the collection of X-ray diffraction data are transforming our ability to study mineral-fluid interactions. The resulting increase in time resolution now allows for the determination of rate laws for mineral reactions that are coupled to atomic-scale changes in crystal structure. Here we address the extension of time-resolved synchrotron diffraction techniques to four areas of critical importance to the cycling of metals in soils: (1) cation exchange; (2) biomineralization; (3) stable isotope fractionation during redox reactions; and (4) nucleation and growth of nanoscale oxyhydroxides.

  15. Application of silica hydrogel and silica gel comprising chromium(III) ions for synthesis of organo mineral cation exchangers

    International Nuclear Information System (INIS)

    Present article is devoted to application of silica hydrogel and silica gel comprising chromium(III) ions for synthesis of organo mineral cation exchangers. Thus, the polymerization of methacrylic acid on the surface of porous silica is studied. Porous sorbents are obtained by polymerizing of methacrylic acid in the medium of precipitated silica hydrogel treated by Cr(III) salts. The dependence of sorbents porosity on different factors, including conditions of hydrogel precipitation, its treatment by chromium salts, its ageing in the medium of methacrylic acid, quantity of methacrylic acid is studied as well.

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

    Directory of Open Access Journals (Sweden)

    V. Romero

    2012-01-01

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

  17. Ion exchange equilibrium constants

    CERN Document Server

    Marcus, Y

    2013-01-01

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

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

    Science.gov (United States)

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

    2008-06-01

    A novel polymeric hybrid sorbent, namely ZrPS-001, was fabricated for enhanced sorption of heavy metal ions by impregnating Zr(HPO3S)2 (i.e., ZrPS) nanoparticles within a porous polymeric cation exchanger D-001. The immobilized negatively charged groups bound to the polymeric matrix D-001 would result in preconcentration and permeation enhancement of target metal ions prior to sequestration, and ZrPS nanoparticles are expected to sequester heavy metals selectively through an ion-exchange process. Highly effective sequestration of lead, cadmium, and zinc ions from aqueous solution can be achieved by ZrPS-001 even in the presence of competing calcium ion at concentration several orders of magnitude greater than the target species. The exhausted ZrPS-001 beads are amenable to regeneration with 6 M HCI solution for repeated use without any significant capacity loss. Fixed-bed column treatment of simulated waters containing heavy metals at high or trace levels was also performed. The content of heavy metals in treated effluent approached or met the WHO drinking water standard. PMID:18589978

  19. Prediction of Heat Removal Capacity of Horizontal Condensation Heat Exchanger submerged in Pool

    International Nuclear Information System (INIS)

    As representative passive safety systems, there are the passive containment cooling system (PCCS) of ESBWR, the emergency condenser system (ECS) of the SWR-1000, the passive auxiliary feed-water system (PAFS) of the APR+ and etc. During the nuclear power plant accidents, these passive safety systems can cool the nuclear system effectively via the heat transfer through the steam condensation, and then mitigate the accidents. For the optimum design and the safety analysis of the passive safety system, it is essential to predict the heat removal capacity of the heat exchanger well. The heat removal capacity of the horizontal condensation heat exchanger submerged in a pool is determined by a combination of a horizontal in-tube condensation heat transfer and a boiling heat transfer on the horizontal tube. Since most correlations proposed in the previous nuclear engineering field were developed for the vertical tube, there is a certain limit to apply these correlations to the horizontal tube. Therefore, this study developed the heat transfer model for the horizontal Ushaped condensation heat exchanger submerged in a pool to predict well the horizontal in-tube condensation heat transfer, the boiling heat transfer on the horizontal tube and the overall heat removal capacity of the heat exchanger using the best-estimate system analysis code, MARS

  20. Effectiveness and humidification capacity investigation of liquid-to-air membrane energy exchanger under low heat capacity ratios at winter air conditions

    Science.gov (United States)

    Kassai, Miklos

    2015-06-01

    In this research, a novel small-scale single-panel liquid-to-air membrane energy exchanger has been used to numerically investigate the effect of given number of heat transfer units (4.5), different cold inlet air temperature (1.7, 5.0, 10.0 °C) and different low heat capacity ratio (0.4, 0.5, 0.6, 0.7, 0.8, 0.9) on the steady-state performance of the energy exchanger. This small-scale energy exchanger represents the full-scale prototypes well, saving manufacturing costs and time. Lithium chloride is used as a salt solution in the system and the steady-state total effectiveness of the exchanger is evaluated for winter inlet air conditions. The results show that total effectiveness of the energy exchanger decreases with heat capacity ratio in the mentioned range. Maximum numerical total effectiveness of 97% is achieved for the energy exchanger. Increasing the heat capacity ratio values on given inlet air temperature, the humidification capacity of energy exhanger is also investigated in this paper. The humidification performance increases with heat capacity ratio. The highest humidification performance (4.53 g/kg) can be reached when inlet air temperature is 1.7 °C, and heat capacity ratio is 1.0 in winter inlet air conditions in the range of low heat capacity ratio.

  1. Improvement of the thermochemical water splitting IS process by an electrochemical cell using a cation exchange membrane

    International Nuclear Information System (INIS)

    One of the key reactions for efficient hydrogen production through the water splitting IS (Iodine-Sulfur) process is the Bunsen reaction (SO2 + I2 + 2H2O = H2SO4 + 2HI). The Bunsen reaction was examined by an electrochemical cell featuring a cation exchange membrane as the separator, using sulfuric acid dissolving sulfur dioxide as the anolyte hydriodic acid dissolving iodine as the catholyte. In galvanostatic electrolysis, molality of H2SO4 in the anolyte and that of HI in the catholyte were increased up to 17.8 mol kg-H2O-1 and 14.9 mol kg-H2O-1 at I2/HI=1, respectively. These concentrations were far higher than the reported ones that were obtained by the Bunsen reaction carried out in the presence of large amount of iodine (e.g. I2/HI=4). The optimal concentrations of anolyte and catholyte were discussed by changing only one parameter. I2/HI ratio had little effects on the required total voltage suggesting that lower I2 concentration is desired for the efficient operation. H2SO4 concentration was found to be lower than 16 mol kg-H2O2-1 for anolyte. One of the important parameter that should be corrected was water content of the cation exchange membrane during the experimental especially for the higher concentrations of anolyte and catholyte. (author)

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

    Science.gov (United States)

    Huang, Jiaoyan; Gustin, Mae Sexauer

    2015-05-19

    Quantifying the concentration of gaseous oxidized mercury (GOM) and identifying the chemical compounds in the atmosphere are important for developing accurate local, regional, and global biogeochemical cycles. The major hypothesis driving this work was that relative humidity affects collection of GOM on KCl-coated denuders and nylon membranes, both currently being applied to measure GOM. Using a laboratory manifold system and ambient air, GOM capture efficiency on 3 different collection surfaces, including KCl-coated denuders, nylon membranes, and cation-exchange membranes, was investigated at relative humidity ranging from 25 to 75%. Recovery of permeated HgBr2 on KCl-coated denuders declined by 4-60% during spikes of relative humidity (25 to 75%). When spikes were turned off GOM recoveries returned to 60 ± 19% of permeated levels. In some cases, KCl-coated denuders were gradually passivated over time after additional humidity was applied. In this study, GOM recovery on nylon membranes decreased with high humidity and ozone concentrations. However, additional humidity enhanced GOM recovery on cation-exchange membranes. In addition, reduction and oxidation of elemental mercury during experiments was observed. The findings in this study can help to explain field observations in previous studies. PMID:25877790

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

    Science.gov (United States)

    El-Sayed, Mayyada; Chase, Howard

    2009-05-01

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

  4. Ion exchange properties of amorphous zirconium phosphate in mixed solvents tracer equilibria, capacity and kinetics of exchange

    International Nuclear Information System (INIS)

    Tracer equilibria measurements for sorption on zirconium phosphate (ZrP) of Na+ in up to 90% methanol and acetone and of Cs+ in up to 90% methanol and 60% isopropanol and acetone have shown that in all these solutions, ion exchange is the main sorption mechanism. With the exception of the Na+ capacity in 90% methanol, the Na+- and Cs+-capacities of ZrP, are higher in solutions containing up to 90% methanol, 60% isopropanol and 60% acetone than in water, which is probably due to the higher basicity of the mixed solvents and a possible dehydration of Na+ and Cs+, particularly in solutions of relatively high organic solvent contents. The diffusion coefficient of Na+ in ZrP decreases on addition of up to 90% methanol and acetone and the decrease is highest in the presence of 90% methanol. (orig.)

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

    Indian Academy of Sciences (India)

    O P Shrivastava; Rashmi Shrivastava

    2000-12-01

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

  6. Study of the Fixation and Migration of Radioactive Cations in a Natural Ion Exchanger

    International Nuclear Information System (INIS)

    With a view to utilizing lignite as a natural ion exchanger in the treatment of radioactive waste, a study was made of its physical and physico-chemical properties with reference to ion exchange. The distribution of Sr90 and Cs137 ions in the presence of Ca, Na and H was first examined and the equilibrium constants calculated. The kinetics and fixation of ions were then studied, and various parameters required for the calculation of ion-exchange beds were established. Study of the complex phenomenon of radioactive ion migration in the soil was started by the separate investigation of each component ionic equilibrium. (author)

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

    Directory of Open Access Journals (Sweden)

    Widajanti Wibowo

    2011-04-01

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

  8. Ionic Liquid Synergistic Cation-Exchange System for the Selective Extraction of Lanthanum(III) Using 2-Thenoyltrifluoroacetone and 18-Crown-6

    OpenAIRE

    Hirayama, Naoki; Okamura, Hiroyuki; Kidani, Keiji; Imura, Hisanori

    2008-01-01

    A novel synergistic extraction system was investigated for the possible selective separation of light lanthanoids using an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, as an extraction solvent and 2-thenoyltrifluoroacetone and 18-crown-6 as extractants. Trivalent lanthanum was efficiently extracted as a cationic ternary complex by the cation-exchange process, whereas europium and lutetium showed relatively low extractability without forming respective ternary ...

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

    International Nuclear Information System (INIS)

    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 searched. 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.

  10. High-Capacity and Rapid Removal of Refractory NOM Using Nanoscale Anion Exchange Resin.

    Science.gov (United States)

    Johnson, Billy R; Eldred, Tim B; Nguyen, Andy T; Payne, William M; Schmidt, Emily E; Alansari, Amir Y; Amburgey, James E; Poler, Jordan C

    2016-07-20

    As human health concerns over disinfection byproducts (DBP) in drinking water increase, so does the need to develop new materials that remove them rapidly and at high capacity. Ion exchange (IEX) is an effective method for the removal of natural organic matter (NOM), especially anion exchange resins (AERs) with quaternary ammonium functional groups. However, capacity is limited in existing commercial resin materials because adsorbates can only interact with the outermost surface area, which makes these products inefficient on a mass basis. We have synthesized a novel "NanoResin" exploiting the enhanced NOM removal of the quaternary ammonium resin while utilizing the vast surface area of SWCNTs, which act as scaffolding for the resin. Our nanomaterials show increased adsorption capacity compared to commercially available adsorbents, in a fraction of the time. This NanoResin requires only about 10 s to reach ion-exchange equilibrium. Comparatively, commercial AERs only achieved partial removal after more than 30 min. High capacity adsorption of a low molecular weight (MW) surrogate has been measured. NOM removal was demonstrated in solutions of both low and high specific UV absorbance (SUVA) composition with these nanomaterials. Additionally, the NanoResin showed enhanced removal of a NOM concentrate sample taken from Myrtle Beach, SC, demonstrating NanoResin is an effective method of removal for refractory NOM in a natural aqueous environment. Synthesis and characterization of the polymers and nanomaterials are presented below. Adsorption capacity, adsorption kinetics, and the regeneration and reusability of these new materials for NOM removal are described. The open matrix microstructure precludes any intraparticle diffusion of adsorbates; thus, these nanomaterials act as a "contact resin". PMID:27348616

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

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

  12. 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.; Post, J.W.; Nijmeijer, K.

    2014-01-01

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

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

    NARCIS (Netherlands)

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

    2014-01-01

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

  14. Kinetics properties of cations absorption by ion exchangers on the base of antimonic acid

    International Nuclear Information System (INIS)

    This article is devoted to study of kinetics of sorption one- and two-charge elements by antimony-silicon sorbent. Kinetic studies are conducted at ph=0-5 and temperature interval 10-50 deg C. Data on X-ray analysis of ion exchangers is considered.

  15. Transport of Zinc and Copper through Impregnated Cation-Exchange Membrane with 8-Hydroxyquinoline Using Electric Field

    International Nuclear Information System (INIS)

    The transport of Zn(II) and Cu(II) species across impregnated cation-exchange membrane with 8-hydroxy-quinoline in xylene was investigated. To accelerate the transport of ions, the effect of electric field was introduced. Certain parameters that affect the transport were studied. These parameters include; hydrochloric acid concentration in the feed solution, stripping solution concentration, voltage and 8-hydroxyquinoline concentration. The flux values of Zn(II) and Cu(II) were 3.7x10-9and 3.6x10-10g-eq.cm-2s-1, respectively. The separation of Zn(II) from Cu(II)was performed selectively by this technique and the use of electric field accelerated the ions transport

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

    Science.gov (United States)

    Hosokawa, Hitoshi; Mochida, Tomoyuki

    2015-12-01

    Solvatochromic nickel(II) complexes with diketonato and diamine ligands were incorporated into a saponite clay by ion exchange, and their colorimetric humidity- and solvent-recognition properties were investigated. These powders exhibit color change from red to blue-green depending on humidity, and the detection range can be controlled by modifying the metal complex. The humidity response takes advantage of the humidity-dependent water content in clay and the coordination of water molecules to the metal complex in equilibrium. The addition of organic solvents to the powders causes a color change to occur, varying from red to blue-green depending on the donor number of the solvent, thereby enabling solvent recognition. In the clay, the affinity of less sterically hindered complexes to water or solvent molecules is decreased compared with that in solution because the cationic complexes interact with the anionic layers in the clay. Incorporating diethylene glycol into the materials produced thermochromic powders. PMID:26542108

  17. On the swelling behavior of cationic exchange resins saturated with Na+ ions in a C3S paste

    International Nuclear Information System (INIS)

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

  18. Onset of size independent cationic exchange in nano-sized CoFe2O4 induced by electronic excitation

    International Nuclear Information System (INIS)

    Highlights: • Electronic excitation induced crystalline order in CoFe2O4. • No change of metallic valence state under dense electronic excitation. • Size independent control of cations in CoFe2O4. - Abstract: Present work investigates electronic excitation induced cationic exchange phenomena in nano-sized cobalt ferrites using Mössabaur and X-ray absorption spectroscopies. The electronic excitations were produced by irradiation of 100 MeV O+7 at different fluences ranging from 1 × 1011 to 1 × 1014 ions/cm2. Cubic spinel phase of cobalt ferrite remains preserved after irradiation. However, attributes of crystalline disorder were observed in irradiated materials. Crystallite size remain almost same for pristine and irradiated materials. X-ray absorption fine structure measurements show the preservation of valence state and spin state of metal ions under intense electronic excitation. These measurements also envisage bond breaking process induced by the electronic excitation. Mössbauer spectroscopic measurements also corroborate with the fine structure measurements that the valence state of Fe remains same after irradiation. Paramagnetic doublet which presents in the Mössabaur spectrum of pristine material disappears after irradiation, showing the evolution of irradiation induced magnetic ordering. Fe3+ ion increases with irradiation at octahedral site of spinel lattice. Magnetization of the material slightly increases after irradiation at the fluence of 5 × 1013 and 1 × 1014 ions/cm2

  19. Cation Exchange Strategy for the Encapsulation of a Photoactive CO-Releasing Organometallic Molecule into Anionic Porous Frameworks.

    Science.gov (United States)

    Carmona, Francisco J; Rojas, Sara; Sánchez, Purificación; Jeremias, Hélia; Marques, Ana R; Romão, Carlos C; Choquesillo-Lazarte, Duane; Navarro, Jorge A R; Maldonado, Carmen R; Barea, Elisa

    2016-07-01

    The encapsulation of the photoactive, nontoxic, water-soluble, and air-stable cationic CORM [Mn(tacn)(CO)3]Br (tacn = 1,4,7-triazacyclononane) in different inorganic porous matrixes, namely, the metalorganic framework bio-MOF-1, (NH2(CH3)2)2[Zn8(adeninate)4(BPDC)6]·8DMF·11H2O (BPDC = 4,4'-biphenyldicarboxylate), and the functionalized mesoporous silicas MCM-41-SO3H and SBA-15-SO3H, is achieved by a cation exchange strategy. The CO release from these loaded materials, under simulated physiological conditions, is triggered by visible light. The results show that the silica matrixes, which are unaltered under physiological conditions, slow the kinetics of CO release, allowing a more controlled CO supply. In contrast, bio-MOF-1 instability leads to the complete leaching of the CORM. Nevertheless, the degradation of the MOF matrix gives rise to an enhanced CO release rate, which is related to the presence of free adenine in the solution. PMID:27291890

  20. Comparison of Reactive Mercury Concentrations Measured Simultaneously Using KCl-coated Denuders, Nylon Membranes, and Cation Exchange Membranes

    Science.gov (United States)

    Gustin, M. S.; Huang, J.; Miller, M. B.; Weiss-Penzias, P. S.

    2012-12-01

    There is much debate about the chemistry of reactive gaseous and particle bound mercury (Hg) in the atmosphere, and the processes associated with formation. In addition, there are concerns regarding the interferences and calibration of the widely used Tekran® 2537/1130/1135 Hg measurement system. To investigate these we developed simple laboratory and field sampling systems designed to collect and analyze reactive Hg (Hg (II), Hg (I) and/or particle bound). A manifold system was applied in the laboratory, and in the field, in-series and -parallel membranes, flow controllers and pumps were utilized. Both systems actively collected reactive Hg using nylon membranes and cation exchange membranes alongside measurements made using the Tekran® system. The analytical system consisted of step wise 2.5 minute thermo-desorption and Hg quantification by cold vapor atomic fluorescence. In the laboratory, we compared the efficiency of these surfaces for collection of HgO, HgCl2, and HgBr2 when permeated into Hg and oxidant free air, and ambient filtered air. Other tests are ongoing. Thus far, results show concentrations measured by the cation exchange membrane were two-to-three fold greater than that measured by the nylon membranes, and three-to -four fold greater than that measured by the KCl-coated annual denuder. Thermo-desorption profiles obtained using nylon membranes show slightly different patterns associated with the reactive Hg compounds as permeated and tested. Field measurements were made at two locations in Reno, Nevada (a high traffic site and an agricultural area) and at Elkhorn Slough, California (marine site). Desorption profiles from nylon membrane differed by site and by time of year. Although the influence of aerosol on this measurement has not been explored, field results suggest different forms of reactive Hg were present in the atmosphere as a function of season and location.

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

    Science.gov (United States)

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

    2003-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-12-01

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

  3. 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: der11065@hotmail.com [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: f10919@ntut.edu.tw [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: sweet39005@hotmail.com [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: hchsi@ntut.edu.tw [Institute of Environmental Engineering and Management, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Rd., Taipei 106, Taiwan (China)

    2013-03-15

    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.

  4. Quantification of melamine in human urine using cation-exchange based high performance liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Panuwet, Parinya; Nguyen, Johnny V; Wade, Erin L; D'Souza, Priya E; Ryan, P Barry; Barr, Dana Boyd

    2012-03-01

    Melamine and cyanuric acid have been implicated as adulterants in baby formula in China and pet foods in North America. In China, the effect of melamine or melamine-cyanuric acid adulteration lead to kidney stone development and acute renal failure in thousands of Chinese infants. A selective and sensitive analytical method was developed to measure melamine in human urine in order to evaluate the extent of potential health implications resulting from the consumption of these types of adulterated products in the general US population. This method involves extracting melamine from human urine using cation-exchange solid-phase extraction, chromatographically separating it from its urinary matrix co-extractants on a silica-based, strong-cation exchange analytical column using high performance liquid chromatography, and analysis using positive mode electrospray ionization tandem mass spectrometry. Quantification was performed using modified, matrix-based isotope dilution calibration covering the concentration range of 0.50-100 ng/mL. The limit of detection, calculated using replicates of blank and low level spiked samples, was 0.66 ng/mL and the relative standard deviations were between 6.89 and 14.9%. The relative recovery of melamine was 101-106%. This method was tested for viability by analyzing samples collected from the general US population. Melamine was detected in 76% of the samples tested, with a geometric mean of 2.37 ng/mL, indicating that this method is suitable for reliably detecting background exposures to melamine or other chemicals from which it can be derived. PMID:22309774

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

    International Nuclear Information System (INIS)

    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 TiO2 loading of 1 g/L was observed at acidic pH with current density 4 mA/cm2. ► 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, TiO2 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/cm2 with the presence of CEM. Higher conversion efficiencies were observed at lower pH due to the electrostatic attractions between positive charged Ti-OH2+, and negatively charged Cr(VI) and EDTA. The optimum TiO2 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

  6. Grafting glycidyl methacrylate to Sepharose gel for fabricating high-capacity protein anion exchangers.

    Science.gov (United States)

    Wang, Qianqian; Yu, Linling; Sun, Yan

    2016-04-22

    To develop ion exchangers of high protein adsorption capacity, we have herein introduced atom transfer radical polymerization (ATRP) method to graft glycidyl methacrylate (GMA) onto Sepharose FF gel. GMA-grafted Sepharose FF resins of four grafting densities and different grafting chain lengths were obtained by adjusting reaction conditions. The epoxy groups on the grafted chains were functionalized by modification with diethylamine (DEA), leading to the fabrication of Sepharose-based anion exchangers of 14 different grafting densities and/or grafting chain lengths. The resins were first characterized for the effects of grafting density, chain length and ionic strength on pore sizes by inverse size exclusion chromatography. Then, the resins were evaluated by adsorption equilibria of bovine serum albumin (BSA) as a function of ionic capacity (IC) (chain length) at individual grafting densities. It was observed that at each grafting density there was a specific IC value (chain length) that offered the maximum equilibrium capacity. Of the resins with maximum values at individual grafting densities, the resin of the second grafting density with an IC value of 330 mmol/L (denoted as FF-Br2-pG-D330) showed the highest capacity, 264 mg/mL, about two times higher than that of the traditional ungrafted resin Q Sepharose FF (137 mg/mL). This resin also showed the most favorable uptake kinetics among the resins of similar IC values but different grafting densities, or of the same grafting density but different IC values. Effects of ionic strength showed that the capacities of FF-Br2-pG-D330 were much higher than Q Sepharose FF at a wide range of NaCl concentrations (0-200 mmol/L), and the uptake rates of the two resins were similar in the ionic strength range. Therefore, the dynamic binding capacity values of BSA on FF-Br2-pG-D330 were much higher than Q Sepharose FF as demonstrated at different residence times and ionic strengths. Taken together, the research has proved the

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

  8. Irradiation effects on the storage and disposal of radwaste containing organic ion-exchange media. [3 functional forms of resin - sulfonic acid cation exchanger, quarternary ammonium anion exchanger and mixed bed combination of the two

    Energy Technology Data Exchange (ETDEWEB)

    Swyler, K.J.; Dodge, C.J.; Dayal, R.

    1983-10-01

    Polystyrene-divinylbenzene (PS-DVB) based ion exchangers are commonly used in water demineralization or decontamination operations at nuclear facilities. Self-irradiation from sorbed radionuclides may affect the properties of radwaste containing these ion-exchange media. The effects of external irradiation on anion, cation, and mixed bed PS-DVB ion exchangers have been investigated under conditions relevant to radwaste storage and disposal. Three effects are emphasized in the present report: (1) release of acids, radionuclides or chemically aggressive species through radiolytic attack on the functional group, (2) radiolytic generation/uptake of corrosive or combustible gases, (3) effect of irradiation on solidification of resins in cement. Special consideration was placed on external variables such as radiation dose rate, resin chemical loading and moisture conditions, accessibility to atmospheric oxygen, and interactions in multicomponent systems. Such variables may affect the correspondence between laboratory results and field performance. 40 references, 24 figures, 28 tables.

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

    Science.gov (United States)

    He, Jian; Giusti, M Monica

    2011-11-01

    Research on biological activity of anthocyanins requires the availability of high purity materials. However, current methods to isolate anthocyanins or anthocyanin mixtures are tedious and expensive or insufficient for complete isolation. We applied a novel cation-exchange/reversed-phase combination solid-phase extraction (SPE) technique, and optimized the use of water/organic buffer mobile phases to selectively separate anthocyanins. Crude extracts of various representative anthocyanin sources were purified with this technique and compared to 3 commonly used SPE techniques: C(18), HLB, and LH-20. Purified anthocyanin fractions were analyzed with high performance liquid chromatography (HPLC) coupled to photodiode array (PDA) and mass spectrometry (MS) detectors and by Fourier transform infrared (FT-IR) spectroscopy. The UV-visible chromatograms quantitatively demonstrated that our novel technique achieved significantly higher (Pmethod, for 11 of the 12 anthocyanin sources tested. Among them, eight were purified to greater than 99% purity (based on UV-visible chromatograms). The new method efficiently removed non-anthocyanin phenolics. MS and FT-IR results semi-quantitatively confirmed extensive reduction of impurities. Due to strong ionic interaction, our sorbent capacity was superior to others, resulting in the highest throughput and least use of organic solvents. This new methodology for isolation of anthocyanin mixtures drastically increased purity and efficiency while maintaining excellent recovery rate and low cost. The availability of high purity anthocyanin mixtures will facilitate anthocyanin studies and promote the application of anthocyanins in the food and nutraceutical industries. PMID:21968344

  10. Increased selectivity for planar chromatography by ion exchange : cation chromatography on papers impregnated with titanium (IV) based inorganic ion exchangers in DMSO-HNO3 mobile phases

    International Nuclear Information System (INIS)

    Planar chromatography of thirty six metal ions on titanium(IV) phosphate, titanium(IV) tungstate and titanium(IV) molybdate impregnated papers in DMSO-HNO3 mobile phases has been carried out. The ion-exchange capacity of papers is determined and the effects of solvent composition, impregnation and pH on RF values are studied. For K+, Rb+ and Cs+, RF = KC1/2, where C is the nitric acid concentration. The movement of ions is explained on the basis of ion-exchange, adsorption and precipitation. Alberti and Torracca's view for the prediction of elution sequence from RF values has been checked. The sequence of adsorption of ions follows the order : titanium(IV) molybdate > titanium(IV) tungstate > titanium(IV) phosphate. Some of the analytically important separations are reported. (author)

  11. The removal of radioactive radium (Ra226) from chloride liquors by columnar ion exchange in the presence of calcium, magnesium and iron cations

    International Nuclear Information System (INIS)

    The purpose of this work was to study the feasibility of controlling the discharge of soluble Ra226, in the presence of Ca, Mg and Fe cations in synthetic chloride effluents, by adsorption on cation exchange resins to decrease Ra226-concentrations to federal environmental levels of 10 pCi Ra226/litre. Environmentally acceptable effluents were produced from synthetic chloride feed liquors containing 10 ppm Ca, 5 ppm Mg, 120 ppm Fe plus 20,000 pCi Ra226/litre. Environmentally acceptable effluents were not produced, by cation exchange, from a synthetic chloride liquor containing 490 ppm Ca, 97 ppm Mg, 720 ppm Fe in addition to 20,000 pCi Ra226/litre. The mass interference of the Ca + Mg + Fe cation concentrations in the feed liquor was in over-powering competition, for resin sites, with the Ra226-cations. To obtain realistic data, the adsorption process should be reexamined using a chloride liquor produced under optimal chloride leaching conditions of an Elliot Lake uranium ore. This would, in all probability, reveal other cations unavailable in the synthetic chloride liquors

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-15

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

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

    International Nuclear Information System (INIS)

    Highlights: • The spent radioactive resins could be oxidized by Fenton-like process. • The influencing factors on resin oxidation were evaluated. • Chemical oxygen demand (COD) reduction rate was more than 99%. • SEM and Raman spectrum were used to analyze the resins morphological change. - Abstract: The treatment and disposal of the spent radioactive resins is essential for the sustainable development of the nuclear industry. In this paper, the disintegration and dissolution of spent cationic resins were studied by Fenton-like process. The influencing factors on resin dissolution, such as pH, temperature, type and concentration of catalysts were evaluated. The results showed that the spent resins could be effectively dissolved at pH < 1, [Fe2+] = 0.2 M and T = 97 ± 2 °C. Chemical oxygen demand (COD) reduction rate was more than 99%. The scanning electron microscopy and the Raman spectrum were used to observe the morphological changes of the spent resins during the dissolution process. Fenton-like oxidation is an efficient method for the volume reduction and stabilization of the spent resins before further immobilization

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

    Science.gov (United States)

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

    2010-01-01

    In order to characterize the ion-exclusion and cation-exchange properties of an unmodified silica-gel column, the retention behaviors of Cr(VI) and Cr(III) ions were investigated using a Develosil 30-5 (150 x 4.6 mm i.d.) in the acidic region. Cr(VI) was separated from other anions by an ion-exclusion and ion-adsorption mechanism, and Cr(III) was separated from other cations with a cation-exchange mechanism. When using 2.0 mM oxalic acid (pH 2.6) as an eluent, a good separation of Cr(VI) and Cr(III) was obtained using conductimetric detection in 12 min. The method was successfully applied to the simultaneous determinations of Cr(VI) and Cr(III) added into tap-water and river-water samples. PMID:20215693

  15. 2-Acrylamido-2-methyl-1-propanesulfonic Acid Grafted Poly(vinylidene fluoride-co-hexafluoropropylene)-Based Acid-/Oxidative-Resistant Cation Exchange for Membrane Electrolysis.

    Science.gov (United States)

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

    2015-12-30

    For developing acid-/oxidative-resistant aliphatic-polymer-based cation-exchange membrane (CEM), macromolecular modification of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) was carried out by controlled chemical grafting of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). To introduce the unsaturation suitable for chemical grafting, dehydrofluorination of commercially available PVDF-co-HFP was achieved under alkaline medium. Sulfonated copolymer (SCP) was prepared by the free radical copolymerization of dehydofluorinated PVDF-co-HFP (DHPVDF-co-HFP) and AMPS in the presence of free radical initiator. Prepared SCP-based CEMs were analyzed for their morphological characteristics, ion-exchange capacity (IEC), water uptake, conductivity, and stabilities (mechanical, chemical, and thermal) in comparison with state-of-art Nafion117 membrane. High bound water content avoids the membrane dehydration, and most optimal (SCP-1.33) membrane exhibited about ∼2.5-fold high bound water content in comparison with that of Nafion117 membrane. Bunsen reaction of iodine-sulfur (I-S) was successfully performed by direct-contact-mode membrane electrolysis in a two-compartment electrolytic cell using different SCP membranes. High current efficiency (83-99%) confirmed absence of any side reaction and 328.05 kJ mol-H2(-1) energy was required for to produce 1 mol of H2 by electrolytic cell with SCP-1.33 membrane. In spite of low conductivity for reported SCP membrane in comparison with that of Nafion117 membrane, SCP-1.33 membrane was assessed as suitable candidate for electrolysis because of its low-cost nature and excellent stabilities in highly acidic environment may be due to partial fluorinated segments in the membrane structure. PMID:26642107

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    Ergot alkaloids are mycotoxins that are undesirable contaminants of cereal products, particularly rye. A method was developed employing clean-up by cation-exchange solid-phase extraction, separation by high-performance liquid chromatography under alkaline conditions and fluorescence detection. It...

  18. Partial exchange of the Li+, Na+ and K+ alkaline cations in the HNi(PO4).H2O layered compound

    International Nuclear Information System (INIS)

    The exchange of the Li+(1), Na+(2) and K+(3) alkaline cations in the layered HNi(PO4).H2O was carried out starting from a methanolic solution containing the Li(OH).H2O hydroxide for (1) and the M(OH) (M=Na and K) hydroxides together with the (C6H13NH2)0.75HNiPO4.H2O phases for (2) and (3). The compounds are stable until, approximately, 280oC for (1) and 400 deg. C for phases (2) and (3), respectively. The IR spectra show the bands belonging to the water molecule and the (PO4)3- oxoanion. The diffuse reflectance spectra indicate the existence of Ni(II), d8, cations in slightly distorted octahedral geometry. The calculated Dq and Racah (B and C) parameters have a mean value of Dq=765, B=905 and C=3895cm-1, respectively, in accordance with the values obtained habitually for this octahedral Ni(II) cation. The study of the exchange process performed by X-ray powder diffraction indicates that the exchange of the Li+ cation in the lamellar HNi(PO4).H2O phase is the minor rapid reaction, whereas the exchange of the Na+ and K+ cations needs the presence of the intermediate (C6H13NH2)0.75HNiPO4.H2O intercalate in order to obtain the required product with the sodium and potassium ions. The Scanning electronic microscopy (SEM) images show a mean size of particle of 5μm. The Li+ exchanged compound exhibits small ionic conductivity (Ωcm-1 is in the 10-8-10-9 range) probably restrained by the methanol solvent. Magnetic measurements carried out from 5K to room temperature indicate antiferromagnetic coupling as the major interaction in the three phases. Notwithstanding the Li and K phases show a weak ferromagnetism at low temperatures

  19. Use of Novel Reinforced Cation Exchange Membranes for Microbial Fuel Cells

    International Nuclear Information System (INIS)

    This work has been focused on the synthesis and characterization of different blended membranes SPEEK-35PVA (Water), SPEEK-35PVA (DMAc) prepared by casting and nanofiber-reinforced proton exchange membranes Nafion-PVA-15, Nafion-PVA-23 and SPEEK/PVA-PVB. The two first reinforced membranes were made up of Nafion® polymer deposited between polyvinyl alcohol (PVA) nanofibers. The last composite membrane is considered because the PVA is a hydrophilic polymer which forms homogeneous blends with SPEEK suitable to obtain high proton conductivity, while the hydrophobic PVB can produce blends in a phase separation morphology in which very low water uptake can be found. The synthesized membranes showed an outstanding stability, high proton conductivity, and enhanced mechanical and barrier properties. The membranes were characterized in single chamber microbial fuel cells (SCMFCs) using electrochemically enriched high sodic saline hybrid H-inocula (Geobacter metallireducen, Desulfurivibrio alkaliphilus, and Marinobacter adhaerens) as biocatalyst. The best performance was obtained with Nafion-PVA-15 membrane, which achieved a maximum power density of 1053 mW/m3 at a cell voltage of 340 mV and displayed the lowest total internal resistance (Rint ≈ 522 Ω). This result is in agreement with the low oxygen permeability and the moderate conductivity found in this kind of membranes. These results are encouraging towards obtaining high concentrated sodic saline model wastewater exploiting MFCs

  20. Determining the Heat Exchange Capacity of Underground Coal Mines in Ohio

    Science.gov (United States)

    Richardson, J. J.; Lopez, D. A.; Leftwich, T. E.; Wolfe, M. E.; Angle, M. P.; Fugitt, F. L.

    2013-12-01

    Conventionally, Ground Source Heat Pumps (GSHP) exploit either saturated bedrock/soils or large surface water bodies as the heat source/sink for the heating and cooling systems. In areas with flooded mines or large subsurface water bodies, it is possible to utilize the water within the voids as the heat source/sink in GSHPs. Utilizing the water within subsurface voids a heat exchanger instead of the traditional saturated bedrock/soils has the potential to be more efficient in heating and cooling applications. The water within the void space is a better thermal conductor than bedrock and soils. Additionally, it is possible that, in a saturated void the heat can be carried away from the exchange site at a greater rate, improving the potential for thermal exchange. This study is focused on characterizing the potential overall heat exchange capacity for flooded mine sites within Ohio. To achieve the overall potential exchange capacity, possible maximum and minimum mine water residence times, effective mine volumes, groundwater recharge rates, maximum and minimum possible linear groundwater velocity, groundwater flow direction, and average ambient mine temperatures were calculated using GIS software and groundwater recharge data from the United States Geological Survey, and characteristics of physical parameters for the mines from the Ohio Geological Survey. The potential linear mine water velocities were calculated by creating a theoretical cross sectional area in the direction of estimated groundwater flow with a respective length of the mine in the direction of groundwater flow and width of the coal bed thickness. It was assumed that all of water entering the mine void exited the through the cross sectional area. By dividing the volume of water entering the mine per year by the cross sectional area, the linear groundwater velocities were estimated. By using the specific heat of water at the estimated temperatures and the volumes of water within the mines, possible

  1. Reversible Dissociation and Ligand-Glutathione Exchange Reaction in Binuclear Cationic Tetranitrosyl Iron Complex with Penicillamine

    Directory of Open Access Journals (Sweden)

    Lidia Syrtsova

    2014-01-01

    Full Text Available This paper describes a comparative study of the decomposition of two nitrosyl iron complexes (NICs with penicillamine thiolic ligands [Fe2(SC5H11NO22(NO4]SO4·5H2O (I and glutathione- (GSH- ligands [Fe2(SC10H17N3O62(NO4]SO4·2H2O (II, which spontaneously evolve to NO in aqueous medium. NO formation was measured by a sensor electrode and by spectrophotometric methods by measuring the formation of a hemoglobin- (Hb- NO complex. The NO evolution reaction rate from (I  k1 = (4.6 ± 0.1·10−3 s−1 and the elimination rate constant of the penicillamine ligand k2 = (1.8 ± 0.2·10−3 s−1 at 25°C in 0.05 M phosphate buffer,  pH 7.0, was calculated using kinetic modeling based on the experimental data. Both reactions are reversible. Spectrophotometry and mass-spectrometry methods have firmly shown that the penicillamine ligand is exchanged for GS− during decomposition of 1.5·10−4 M (I in the presence of 10−3 M GSH, with 76% yield in 24 h. As has been established, such behaviour is caused by the resistance of (II to decomposition due to the higher affinity of iron to GSH in the complex. The discovered reaction may impede S-glutathionylation of the essential enzyme systems in the presence of (I and is important for metabolism of NIC, connected with its antitumor activity.

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

    Science.gov (United States)

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

    2016-01-01

    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. PMID:26647158

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

    International Nuclear Information System (INIS)

    Highlights: • We investigated deposition of a mixed CdSe-CdS-Ag2Se-Ag2S on polyamide. • A single chalcogen precursor – K2SeS2O6 – was used. • AAS showed five- to ten-fold excess of chalcogens diffused into PA. • Addition of AgNO3 resulted in subsurface Ag2Se–Ag2S formation. - Abstract: Thin mixed CdSe-CdS-Ag2Se-Ag2S films were deposited on a polyamide 6 (PA) surface by successfully using a cation-exchange reaction between Cd2+ and Ag+ to convert CdSe-CdS into Ag2Se-Ag2S. These were deposited using a K2SeS2O6 precursor solution at 60 °C followed by cadmium acetate (Cd(CH3COO)2). An aqueous AgNO3 solution was used as the Ag source. XRD patterns showed a complex PA-Cd-S-Se-Ag film crystalline composition with CdS, CdSe, Ag2S and Ag2Se peaks. Calculated dislocation density ranged within 5–15 × 1013 lines·m−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 Ag2O

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-01

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

  5. Ionic liquid synergistic cation-exchange system for the selective extraction of lanthanum(III) using 2-thenoyltrifluoroacetone and 18-crown-6.

    Science.gov (United States)

    Hirayama, Naoki; Okamura, Hiroyuki; Kidani, Keiji; Imura, Hisanori

    2008-06-01

    A novel synergistic extraction system was investigated for the possible selective separation of light lanthanoids using an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, as an extraction solvent and 2-thenoyltrifluoroacetone and 18-crown-6 as extractants. Trivalent lanthanum was efficiently extracted as a cationic ternary complex by the cation-exchange process, whereas europium and lutetium showed relatively low extractability without forming respective ternary complexes. This result is thought to originate in a size-fitting effect of 18-crown-6 to lanthanum and the unique nature of the ionic liquid as a chelate extraction solvent. PMID:18544855

  6. The k{sub 0}-INAA method for the determination of the anion-exchange capacity of propylpyridium silicas

    Energy Technology Data Exchange (ETDEWEB)

    Auler, Lucia M.L.A.; Menezes, Maria Angela de B.C.; Amaral, Angela Maria [Centro de Desenvolvimento de Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)]. E-mail: aulerlm@cdtn.br; Silva, Cesar R.; Collins, Kenneth E.; Collins, Carol [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica. Lab. de Cromatografia Liquida (LABCROM)]. E-mail: chc@iqm.unicamp.br

    2005-07-01

    The present work describes the k{sub 0}-INAA method as an alternative for determination of the ion-exchange capacity of a propyl pyridinium modified silica, which has been recently employed as stationary phase for anion -exchange chromatography. The exchange capacity of the modified silicas was investigated by determining its exchangeable chloride content with k{sub 0}-Instrumental Neutron Activation Analyses. Irradiation experiments were performed in the reactor TRIGA Mark I IPR-R1 located at CDTN/CNEN (Nuclear Technology Development Center / Nuclear Energy National Commission). The results showed that the exchangeable chloride concentration was successfully determined by this analytical method instead of the conventional potentiometric determination with silver nitrate titrimetry. (author)

  7. A continuous process for biodiesel production in a fixed bed reactor packed with cation-exchange resin as heterogeneous catalyst.

    Science.gov (United States)

    Feng, Yaohui; Zhang, Aiqing; Li, Jianxin; He, Benqiao

    2011-02-01

    Continuous esterification of free fatty acids (FFA) from acidified oil with methanol was carried out with NKC-9 cation-exchange resin in a fixed bed reactor with an internal diameter of 25 mm and a height of 450 mm to produce biodiesel. The results showed that the FFA conversion increased with increases in methanol/oil mass ratio, reaction temperature and catalyst bed height, whereas decreased with increases in initial water content in feedstock and feed flow rate. The FFA conversion kept over 98.0% during 500 h of continuous esterification processes under 2.8:1 methanol to oleic acid mass ratio, 44.0 cm catalyst bed height, 0.62 ml/min feed flow rate and 65°C reaction temperature, showing a much high conversion and operational stability. Furthermore, the loss of sulfonic acid groups from NKC-9 resin into the production was not found during continuous esterification. In sum, NKC-9 resin shows the potential commercial applications to esterification of FFA. PMID:21078550

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

    Science.gov (United States)

    Hsu, Hung-Te; Chen, Shiao-Shing; Tang, Yi-Fang; Hsi, Hsing-Cheng

    2013-03-15

    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, TiO2 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 4mA/cm(2) with the presence of CEM. Higher conversion efficiencies were observed at lower pH due to the electrostatic attractions between positive charged TiOH2(+), and negatively charged Cr(VI) and EDTA. The optimum TiO2 loading of 1g/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. PMID:23380448

  9. Kinetics, thermodynamics and surface heterogeneity assessment of uranium(VI) adsorption onto cation exchange resin derived from a lignocellulosic residue

    International Nuclear Information System (INIS)

    A new cation exchange resin (PGTFS-COOH) having a carboxylate functional group at the chain end was prepared by grafting poly(hydroxyethylmethacrylate) onto tamarind fruit shell, TFS (a lignocellulosic residue) using potassium peroxydisulphate-sodium thiosulphate redox initiator, and in the presence of N,N'-methylenebisacrylamide (MBA) as a crosslinking agent, followed by functionalisation. The adsorbent was characterized with the help of FTIR, XRD, scanning electron micrographs (SEM), and potentiometric titrations. The kinetic and isotherm data, obtained at optimum pH value 6.0 at different temperatures could be fitted with pseudo-second-order equation and Sips isotherm model, respectively. An increase in temperature induces positive effect on the adsorption process. The calculated activation energy of adsorption (Ea, 18.67 kJ/mol) indicates that U(VI) adsorption was largely due to diffusion-controlled process. The values of adsorption enthalpy, Gibbs free energy, and entropy were calculated using thermodynamic function relationships. The decrease in adsorption enthalpy with increasing U(VI) uploading on the adsorbent, reflects the surface energetic heterogeneity of the adsorbent. The isosteric heat of adsorption was quantitatively correlated with the fractional loading for the U(VI) ions adsorption onto PGTFS-COOH. The results showed that the PGTFS-COOH possessed heterogeneous surface with sorption sites having different activities.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-15

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

  11. Cation exchange separation of 61Cu2+ from natCo targets and preparation of 61Cu-DOTA-HSA as a blood pool agent

    International Nuclear Information System (INIS)

    An improved method for isolation of 61Cu2+ from a natCo target using cation exchange was developed. 61Cu2+ was eluted from a cation exchange resin column by 0.2 M HCl with 90% acetone, while Co2+ remained on the column. The whole separation process was completed within 50 min at more than 72% yield. The Co2+ impurity level in 61Cu2+ solution was reduced to less than 0.1 ppm. Highly pure 61Cu2+ solution was then applied to prepare 61Cu-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-human serum albumin (HSA) which showed good blood pool imaging properties

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

    Science.gov (United States)

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

    1993-01-01

    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).

  13. Method for encapsulating and isolating hazardous cations, medium for encapsulating and isolating hazardous cations

    Energy Technology Data Exchange (ETDEWEB)

    Wasserman, S.R.; Anderson, K.B.; Song, K.; Yuchs, S.E.; Marshall, C.L.

    1996-12-31

    The problems associated with the disposal of toxic metals in an environmentally acceptable manner continues to plague industry. Such metals as nickel, vanadium, molybdenum, cobalt, iron, and antimony present physiological and ecological challenges that are best addressed through minimization of exposure and dispersion. A method for encapsulating hazardous cations is provided comprising supplying a pretreated substrate containing the cations; contacting the substrate with an organo-silane compound to form a coating on the substrate; and allowing the coating to cure. A medium for containing hazardous cations is also provided, comprising a substrate having ion-exchange capacity and a silane-containing coating on the substrate.

  14. 离子色谱分离法提纯异麦芽低聚糖%Purification of isomalto-oligosaccharide by cation exchange chromatography

    Institute of Scientific and Technical Information of China (English)

    姜守霞; 励雯波; 钟振声

    2003-01-01

    The purification of isomalto-oligsaccharide syrup using cation exchange resin was smdiied. The experiments showed that, when 35 ml raw material was used, the optimal purification result could be achieved on the resin column of 9 × 4000 mm with eluting rate 9 ml/min at 71℃ .The content of gluecose could be decreased whist the content of active components would be relatively increased.The purity of isomalto-oligsaccharide could be further increased by re-purification.

  15. Liquid-liquid extraction and separation of VIII group elements, especially ruthenium, by synergic combinations or aromatic polyimines and micellar cationic exchangers

    International Nuclear Information System (INIS)

    This thesis aims to characterize and to quantify the chemical equilibria involved in d-elements liquid-liquid extraction systems, especially elements belonging to the VIII group (Fe, Ni, Co, Ru, Rh, Pd, Pt). These systems are composed of synergic combination of aromatic polyimines and micellar cationic exchangers. Substitutions are first performed in aqueous acidic media by aromatic polyimines; then extractions are operated using micellic canionic exchangers. Chemical equilibria, selectivity effects, especially those due to ion-pair formations, kinetics, extractant behaviour are analysed and quantified

  16. Thermodynamics of the extraction of scandium(III) by the liquid cation exchangers dinonylnaphthalenesulfonic acid and bis(2-ethylhexyl) phosphoric acid

    International Nuclear Information System (INIS)

    The thermodynamic functions for the extraction of Sc3+ by liquid cation exchangers HD and HDEHP are determined radiometrically by the temperature coefficient method. The role of the diluent dielectric constant on the extraction of Sc3+ by HD is also studied. The thermodynamic parameters determined indicated that the free energy variation for the extraction of Sc3+ by HD is mainly determined by the entropic terms arising from the hydration-dehydration process of the exchanged ions. In the case of HDEHP as extractant, the free energy variations are determined mainly by the entalpic terms of the system. (author)

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

    International Nuclear Information System (INIS)

    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 103 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-02-25

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

  19. Ion exchange selectivity and kinetics on hydrous oxides and their dependence on their acidity, capacity, surface area, pore structure and crystallinity

    International Nuclear Information System (INIS)

    In the present work hydrous alumina, ferric oxide, ceria and tin oxide were prepared by different methods and subjected to X-ray, infra-red, thermal and porous texture analysis. Alkali cation and halide ion selectivity coefficients were measured under different conditions, and diffusion coefficients of Cs+ in two alumina samples and of Na+ in three iron oxide gels heated at different temperatures were determined by tracer diffusion. Besides, equilibrium distribution of U, Ce, La, Eu, Fe, Co, Ni, Sr, Ba, Na and Cs on ceria and tin oxide were measured under a variety of conditions. The results obtained in the present work have shown that OH groups and/or H2O molecules present on the surface of hydrous oxides act as the exchange sites. In the amorphous or microcrystalline samples, the OH groups start to condense at temperatures as low as 100 deg. C. The surface area is generally a poor factor in determining the ion exchange capacity. The kinetic studies have shown that ion mobility decreases with the decrease of pore size, increase of capacity, and decrease of site acidity. The latter two factors lead to the increase of the strength of interaction of the ion with the exchange sites. The equilibrium distribution measurements of several ions on ceria and tin oxide point to a possible use of both oxides in the separation of uranium from all the other elements and in the separation of elements or groups of elements from each other. In this respect, ceria seems to be more attractive

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

    Science.gov (United States)

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

    2016-07-01

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

  1. Retrofitting of heat exchanger networks involving streams with variable heat capacity: Application of single and multi-objective optimization

    International Nuclear Information System (INIS)

    Heat exchanger network (HEN) retrofitting improves the energy efficiency of the current process by reducing external utilities. In this work, HEN retrofitting involving streams having variable heat capacity is studied. For this, enthalpy values of a stream are fitted to a continuous cubic polynomial instead of a stepwise approach employed in the previous studies [1,2]. The former methodology is closer to reality as enthalpy or heat capacity changes gradually instead of step changes. Using the polynomial fitting formulation, single objective optimization (SOO) and multi-objective optimization (MOO) of a HEN retrofit problem are investigated. The results obtained show an improvement in the utility savings, and MOO provides many Pareto-optimal solutions to choose from. Also, Pareto-optimal solutions involving area addition in existing heat exchangers only (but no new exchangers and no structural modifications) are found and provided for comparison with those involving new exchangers and structural modifications as well. - Highlights: • HEN retrofitting involving streams with variable heat capacities is studied. • A continuous approach to handle variable heat capacity is proposed and tested. • Better and practical solutions are obtained for HEN retrofitting in process plants. • Pareto-optimal solutions provide many alternate choices for HEN retrofitting

  2. Performance Comparison Of Round Tubes Finned Heat Exchangers And Macro Micro-Channel Heat Exchangers In A Low Capacity Heat Pump

    OpenAIRE

    Zoughaib, A; Mortada, S; Khayat, F; Arzano-Daurelle, C; Teuillieres, C

    2014-01-01

    Micro-channel heat exchangers (MCHE) are used in automobile applications due to their low weight and high compactness. Those MCHE are just gaining interest in stationary application and they have a great potential for low heating capacity heat pumps to be installed in “passive houses” where the heating demand is 3 to 5 times lower than in the current new individual houses built in European countries. In this paper, a low capacity integrated air to air heat pump prototype is used to perform an...

  3. Potential Modulated Intercalation of Alkali Cations into Metal Hexacyanoferrate Coated Electrodes

    International Nuclear Information System (INIS)

    Nickel hexacyanoferrate is a polynuclear inorganic ion intercalation material that loads (intercalates) and elutes (deintercalates) alkali cations from its structure when electrochemically reduced and oxidized, respectively. Nickel hexacyanoferrrate (NiHCF) is known to preferentially intercalate cesium over all other alkali cations, thus providing a basis for a separation scheme that can tackle DOE's radiocesium contamination problem. This program studied fundamental issues in alkalization intercalation and deintercalation in nickel hexacyanoferrate compounds, with the goal of (1) quantifying the ion exchange selectivity properties from cation mixtures, (2) enhancing ion exchange capacities, and (3) and understanding the electrochemically-switched ion exchange process (ESIX)

  4. Use of new tandem cation/anion exchange system with clinical-scale generators provides high specific volume solutions of technetium-99m and rhenium-188

    International Nuclear Information System (INIS)

    In this paper we describe the first application of our simple and inexpensive post-elution tandem cation/anion exchange column system which is based on generator elution with salts of weak acids such as ammonium acetate instead of saline solution to provide very high specific volume solutions of technetium-99m and rhenium-188 from clinical-scale molybdenum-99/technetium-99m generator prepared from low specific activity (n,y) molybdenum-99, and tungsten-188/rhenium-188 generators, respectively. Initial passage of the bolus through a strong cation exchange cartridge converts the ammonium acetate to acetic acid which is essentially not ionized at the acidic pH, allowing specific subsequent amine-type (QMA SepPak TM) anion exchange cartridge column trapping of the microscopic levels of the pertechnetate or perrhenate. Subsequent elution of the anion cartridge with a small volume (500 mCi/mL) from the alumina-based tungsten-188/rhenium-188 generator. (author)

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

    Directory of Open Access Journals (Sweden)

    Supitcha Rungrodnimitchai

    2014-01-01

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

  6. Properties of solvated electrons, alkali anions and other species in metal solutions and kinetics of cation and electron exchange reactions. Final report

    International Nuclear Information System (INIS)

    The properties of solutions of alkali metals in amine solvents were studied by optical, ETR, NMR and electrochemical methods. Complexation of the alkali cations by crown ethers and cryptands permitted the preparation of concentrated solutions of alkali metals in amine and ether solvents. Extensive alkali metal NMR studies of the exchange of M+ with crown-ethers and cryptands and of the alkali metal anion, M-, were made. The first crystalline salt of an alkali metal anion, Na+ Cryptand [2.2.2]Na- was synthesized and characterized and led to the preparation of other alkali metal anion salts. This research provided the foundation for continuing studies of crystalline alkalide salts

  7. Studies on the removal of trace amounts of 137Cs and 90Sr from low level effluents using PSS type cation exchanger

    International Nuclear Information System (INIS)

    Usability of commercial polystyrene sulphonate cation exchanger, for the removal of trace concentrations of 137Cs and 90Sr from low level effluent stream generated from nuclear installations is studied. Batch sorption experiments are carried out under different experimental conditions from 137Cs and 90Sr spiked aqueous solutions of varied pH to evaluate and establish suitable operating parameters for the removal of the two most potentially mobile radionuclides. Results show that the resin can be used for the sorption of these radionuclide from spent fuel pond as well as from waste streams containing low concentrations of salt. (author)

  8. A cation exchange method for separation of 111In from inactive silver, copper, traces of iron and radioactive gallium and zinc isotopes

    International Nuclear Information System (INIS)

    111In was produced by the 109Ag(α, 2n)111In reaction. A simple radiochemical separation technique, using Dowex-50 cation exchange resin (with prior removal of copper bulk, if present), has been employed to separate radioindium from inactive contaminants like Ag, Cu, Fe and active contaminant like 67Ga and 65Zn. The radiochemical separation yield was 90-99%. The radionuclide purity of 111In was >99% at 60 h after EOB. The level of all the inactive contaminants was <5 μg/mL in the final product. (Author)

  9. A comparative account of the wet oxidation of cation exchange resin with hydrogen peroxide using titanium, vanadium, and molybdenum doped MCM-41 as catalysts

    International Nuclear Information System (INIS)

    Ion exchange resins are widely used in the nuclear industry for treatment of radioactive waste as well as for the upgrading of heavy water used in the primary heat transport system and moderator system. Repeated usage of the resins calls for replacement and treatment before disposal. The present work involves the application of metal-doped MCM-41 material as a catalyst for the wet oxidation of cation exchange resins using hydrogen peroxide as an oxidizing agent. The sulfate produced from the exchangeable group of the resin reflects the extent of decomposition and the carbonate produced reflects the extent of oxidation of the ion exchange resin. Results indicate that the percentage decomposition and oxidation increase with the weight of the catalyst and the volume of the oxidant, i.e., hydrogen peroxide. As much as 0.5 g of the resin could be decomposed by 12 mL of 30% hydrogen peroxide to 98.7% and oxidized to 99.25% using molybdenum doped MCM-41. Vanadium doped and titanium doped MCM-41 required 14 to 16 mL for complete decomposition and 18 to 20 mL for complete oxidation of the ion exchange resin. (orig.)

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

    Directory of Open Access Journals (Sweden)

    Abdulselam Ertaş

    2014-07-01

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

  11. Pulmonary Hypertension in Patients with Idiopathic Pulmonary Fibrosis – The Predictive Value of Exercise Capacity and Gas Exchange Efficiency

    OpenAIRE

    Gläser, Sven; Obst, Anne; Koch, Beate; Henkel, Beate; Grieger, Anita; Stephan B. Felix; Halank, Michael; Bruch, Leonhard; Bollmann, Tom; Warnke, Christian; Schäper, Christoph; Ewert, Ralf

    2013-01-01

    Exercise capacity and survival of patients with IPF is potentially impaired by pulmonary hypertension. This study aims to investigate diagnostic and prognostic properties of gas exchange during exercise and lung function in IPF patients with or without pulmonary hypertension. In a multicentre setting, patients with IPF underwent right heart catheterization, cardiopulmonary exercise and lung function testing during their initial evaluation. Mortality follow up was evaluated. Seventy-three of 1...

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

    Institute of Scientific and Technical Information of China (English)

    李志红; 罗行; 华贵; W.Roetzel

    2004-01-01

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

  13. Ion-exclusion chromatography with conductimetric detection of aliphatic carboxylic acids on a weakly acidic cation-exchange resin by elution with benzoic acid-beta-cyclodextrin.

    Science.gov (United States)

    Tanaka, Kazuhiko; Mori, Masanobu; Xu, Qun; Helaleh, Murad I H; Ikedo, Mikaru; Taoda, Hiroshi; Hu, Wenzhi; Hasebe, Kiyoshi; Fritz, James S; Haddad, Paul R

    2003-05-16

    In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression. PMID:12830884

  14. Superconductivity of 132 K in HgBa2Ca2Cu3O8+δ thin films fabricated using a cation exchange method

    International Nuclear Information System (INIS)

    A cation exchange method was applied to convert epitaxial TlBa2Ca2Cu3O8 (Tl-1223) and Tl2Ba2Ca2Cu3O10 (Tl-2223) precursor superconducting thin films to epitaxial HgBa2Ca2Cu3O8+δ (Hg-1223) films on LaAlO3 (001) substrates. While the conversion of Tl-1223 to Hg-1223 was partially successful, high-quality epitaxial Hg-1223 films were obtained from Tl-2223 precursor films. A critical transition temperature Tc of up to 132 K has been demonstrated for the Hg-1223 films, which is close to the optimal value of 135 K reported on Hg-1223 bulk samples. The critical current density Jc of the Hg-1223 films was up to 0.25 MA cm−2 at 77 K and self-field. This work represents the first success in achieving the highest-Tc epitaxial Hg-1223 films using the cation exchange method, which are promising candidates for device applications with operational temperatures significantly above the temperature of liquid nitrogen. (paper)

  15. Cation Exchange Combined with Kirkendall Effect in the Preparation of SnTe/CdTe and CdTe/SnTe Core/Shell Nanocrystals.

    Science.gov (United States)

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

    2016-07-01

    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. PMID:27331900

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

    Science.gov (United States)

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

    2015-03-01

    The objective of this investigation was to evaluate gas exchange and cardiopulmonary functional behavior in patients with pulmonary hypertension (PH) before, during and after the change to a prone position. Thirty patients with PH and alterations in gas exchange were included in the study. Gas exchange measurements were performed in four stages: at the baseline supine position and after 30, 120 and 240 minutes in prone position. Also, the patients were evaluated by the six minutes walking test (6MWT) after 30 days in prone position during night's sleep. After four hours in prone position, all patients showed an increase of PaO2 and arterial saturation of oxygen (SaO2), with a decrease of intrapulmonary shunts, improving the gas exchange and therefore the physiological demand imposed by exercise in patients with PH. PMID:25920183

  17. Thermodynamics of ion exchange of trivalent Cosup(III) or Crsup(III) complex with cerium(III) ions on cation exchange resin

    International Nuclear Information System (INIS)

    The thermodynamic values of ion exchange of [M(B)sub(n)(H2O)sub(6-n)]3+ [M = Cosup(III) or Crsup(III), B = NH3, (ethylenediamine = en)/2, (1,3-diaminopropane = tn)/2, (1,2-diaminopropane = pn)/2 or urea, 0 =3+ ions on Dowex 50W resin of 2,8 or 16% divinylbenzene (DVB) content were determined from selectivity coefficient and heat of exchange measurements at 250C. Further, the equivalent volumes of [M(B)sub(n)(H2O)sub(6-n)]3+-form resins of 2% DVB content were measured. The heat and entropy of exchange were negative for the preferential uptake of [MB6]3+ by Ce3+-form resin of 2% DVB content and they vary significantly with the ligand, B. The sequence of their values is given. From the entropy of exchange on 2% DVB resin, it seems that the interaction between the complex ion and water depends on the surface charge density of complex ion. Further, the heat of exchange on 2% DVB resin and the equivalent volume of resin are explained in terms of the interaction between the complex ion and water. (author)

  18. Pulmonary hypertension in patients with idiopathic pulmonary fibrosis - the predictive value of exercise capacity and gas exchange efficiency.

    Directory of Open Access Journals (Sweden)

    Sven Gläser

    Full Text Available Exercise capacity and survival of patients with IPF is potentially impaired by pulmonary hypertension. This study aims to investigate diagnostic and prognostic properties of gas exchange during exercise and lung function in IPF patients with or without pulmonary hypertension. In a multicentre setting, patients with IPF underwent right heart catheterization, cardiopulmonary exercise and lung function testing during their initial evaluation. Mortality follow up was evaluated. Seventy-three of 135 patients [82 males; median age of 64 (56; 72 years] with IPF had pulmonary hypertension as assessed by right heart catheterization [median mean pulmonary arterial pressure 34 (27; 43 mmHg]. The presence of pulmonary hypertension was best predicted by gas exchange efficiency for carbon dioxide (cut off ≥152% predicted; area under the curve 0.94 and peak oxygen uptake (≤56% predicted; 0.83, followed by diffusing capacity. Resting lung volumes did not predict pulmonary hypertension. Survival was best predicted by the presence of pulmonary hypertension, followed by peak oxygen uptake [HR 0.96 (0.93; 0.98]. Pulmonary hypertension in IPF patients is best predicted by gas exchange efficiency during exercise and peak oxygen uptake. In addition to invasively measured pulmonary arterial pressure, oxygen uptake at peak exercise predicts survival in this patient population.

  19. Applying reactive models to column experiments to assess the hydrogeochemistry of seawater intrusion: Optimising ACUAINTRUSION and selecting cation exchange coefficients with PHREEQC

    Science.gov (United States)

    Boluda-Botella, N.; Valdes-Abellan, J.; Pedraza, R.

    2014-03-01

    Three sets of laboratory column experimental results concerning the hydrogeochemistry of seawater intrusion have been modelled using two codes: ACUAINTRUSION (Chemical Engineering Department, University of Alicante) and PHREEQC (U.S.G.S.). These reactive models utilise the hydrodynamic parameters determined using the ACUAINTRUSION TRANSPORT software and fit the chloride breakthrough curves perfectly. The ACUAINTRUSION code was improved, and the instabilities were studied relative to the discretisation. The relative square errors were obtained using different combinations of the spatial and temporal steps: the global error for the total experimental data and the partial error for each element. Good simulations for the three experiments were obtained using the ACUAINTRUSION software with slight variations in the selectivity coefficients for both sediments determined in batch experiments with fresh water. The cation exchange parameters included in ACUAINTRUSION are those reported by the Gapon convention with modified exponents for the Ca/Mg exchange. PHREEQC simulations performed using the Gains-Thomas convention were unsatisfactory, with the exchange coefficients from the database of PHREEQC (or range), but those determined with fresh water - natural sediment allowed only an approximation to be obtained. For the treated sediment, the adjusted exchange coefficients were determined to improve the simulation and are vastly different from those from the database of PHREEQC or batch experiment values; however, these values fall in an order similar to the others determined under dynamic conditions. Different cation concentrations were simulated using two different software packages; this disparity could be attributed to the defined selectivity coefficients that affect the gypsum equilibrium. Consequently, different calculated sulphate concentrations are obtained using each type of software; a smaller mismatch was predicted using ACUAINTRUSION. In general, the presented

  20. Flooding tolerance of Carex species. II. Root gas-exchange capacity

    NARCIS (Netherlands)

    Moog, PR; Bruggemann, W

    1998-01-01

    Root CO2 and O-2 gas exchange were measured in young Carer extensa Good. (flooding sensitive), C. remota L. and C. pseudocyperus L. (both flooding tolerant) plants, precultured either aerobically or anaerobically. Temperature changes form 21 to II degrees C had small effects on root CO2 release from

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-15

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

  2. Effect of bore fluid composition on microstructure and performance of a microporous hollow fibre membrane as a cation-exchange substrate.

    Science.gov (United States)

    Lazar, R A; Mandal, I; Slater, N K H

    2015-05-15

    Micro-capillary film (MCF) membranes are effective platforms for bioseparations and viable alternatives to established packed bed and membrane substrates at the analytical and preparative chromatography scales. Single hollow fibre (HF) MCF membranes with varied microstructures were produced in order to evaluate the effect of the bore fluid composition used during hollow fibre extrusion on their structure and performance as cation-exchange adsorbers. Hollow fibres were fabricated from ethylene-vinyl alcohol (EVOH) copolymer through solution extrusion followed by nonsolvent induced phase separation (NIPS) using bore fluids of differing composition (100wt.% N-methyl-2-pyrrolidone (NMP), 100wt.% glycerol, 100wt.% water). All HFs displayed highly microporous and mesoporous microstructures, with distinct regions of pore size membrane performance as a result of inner surface porosity was established with a view to applying this parameter for the optimisation of multi-capillary MCF performance in future studies. PMID:25840664

  3. A fast method for the determination of Sr-90 in liquid milk by solid phase extraction with cryptand 222 on cation exchange resin

    International Nuclear Information System (INIS)

    A method for determining the activity of Sr-90 in liquid milk samples that does not require the usual drying, ashing, acid leaching and precipitation procedures is described. Two solid phase extractants are used, namely: Cryptand 222 bound to a cation exchange resin, and Eichrome Industries' Sr.Spec Resin trademark. These are applied respectively to extract Sr-90 from the milk and to isolate it in a form suitable for measurement by low-level liquid scintillation counting. The results of analyses of 1 liter milk samples contaminated with a known activity of Sr-90 agreed well with the expected values. It was also found that Sr.Spec Resin trademark can be regenerated and re-used several times. As the method requires only minimal operator skill and time, many samples can be analyzed simultaneously. (orig.)

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

    International Nuclear Information System (INIS)

    Silicic tuffs of the southern Great Basin and basalts of the Columbia River Plateau are under investigation as potential host rocks for high- and intermediate-level radioactive wastes. Nonwelded and partially welded tuffs may contain major amounts (> 50%) of the zeolite minerals clinoptilolite, mordenite, and analcime. Densely welded tuffs and some basalt flows may contain clinoptilolite as fracture filling that limits the permeability of these rocks. The cation exchange properties of these zeolite minerals allow them to pose a formidable natural barrier to the migration of cationic species of various radionuclides in aqueous solutions. However, these minerals are unstable at elevated temperatures and at low water-vapor pressures and may break down either by reversible dehydration or by irreversible mineralogical reactions. All the breakdown reactions occurring at increased temperature involve a net volume reduction and evolution of fluids. Thus, they may provide a pathway (shrinkage fractures) and a driving force (fluid pressure) for release of radionuclides to the biosphere. These reactions may be avoided by keeping zeolite-bearing horizons saturated with water and below about 850C. This may restrict allowable gross thermal loadings in waste repositories in volcanic rocks

  5. 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

    2012-01-01

    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.

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

    Science.gov (United States)

    Sun, Yingxin; Mao, Xinfeng; Pei, Supeng

    2016-02-01

    A two-layer ONIOM study on the hydrodesulfurization mechanism of thiophene in H-FAU and M-FAU (M = Li(+), Na(+), and K(+)) has been carried out. The calculated results reveal that in H-FAU, for a unimolecular mechanism, the rate-determining step is hydrogenation of alkoxide intermediate. The assistance of H2O and H2S molecules does not reduce the difficulty of the C-S bond cracking step more effectively. A bimolecular hydrodesulfurization mechanism is more favorable due to the lower activation barriers. The rate-determining step is the formation of 2-methylthiophene, not the C-S bond cracking of thiophene. Moreover, the ring opening of thiophene is much easier to occur than the desulfurization step. A careful analysis of energetics indicates that H2S, propene, and methyl thiophene are the major products for the hydrodesulfurization process of thiophene over H-FAU zeolite, in good agreement with experimental findings. In M-FAU zeolites, both unimolecular and bimolecular cracking processes are difficult to occur because of the high energy barriers. Compared to the case on H-FAU, the metal cations on M-FAU increase the difficulty of occurrence of bimolecular polymerization and subsequent C-S bond cracking steps. Graphical abstract Hydrodesulfurization process of thiophene can take place in H-FAU zeolite. Two different mechanisms, unimolecular and bimolecular ones, have been proposed and evaluated in detail. The bimolecular mechanism is more favorable due to lower activation barrier as described in the picture above. Our calculated data indicate that H2S, propene, and methylthiophene are the major products, in good agreement with experimental observations. The effect of metal cations on the reaction mechanism is also investigated in this work. PMID:26841976

  7. Seismic capacity evaluation of a group of vertical U-tube heat exchanger with support frames for seismic PSA

    International Nuclear Information System (INIS)

    This paper presents an evaluation of seismic capacity of a group of vertical U-tube type heat exchangers (HXs) with support frames to contribute to refinement of seismic capacity data for seismic Probabilistic Safety Assessment (PSA) in Japan. According to usual practice of seismic PSAs, capacity of component is represented as a log-normally distributed random variable defined by a median and logarithmic standard deviations (LSDs), which represent inherent randomness about the median, β r, and uncertainty in the median due to lack of knowledge, β u. Using design specifications of four HXs for residual heat removal systems of 1100 MWe BWRs, the authors evaluated a generic capacity of HXs with a LSD for uncertainty due to lack of knowledge to take into account design variability. The median capacity was evaluated by the use of a time history response analysis with a detailed model for a selected representative HX, which was extended from a model used in seismic design. The LSD for uncertainty due to lack of knowledge was evaluated with consideration of the variabilities in three influential design parameters, i.e., diameter of anchor bolt, weight of HX and position of center of gravity of HX with the detailed model and a simplified static model. The LSD for uncertainty due to randomness was determined from the variability in material property. The dominant failure mode of HXs was identified as the failure of anchor bolts of lugs mainly due to shearing stress. The capacity expressed in terms of zero period acceleration on the foundation of HX was evaluated to be 4180 Gal (4.3 g) for median, LSD for uncertainty due to randomness was 0.11 and LSD due to lack of knowledge was 0.21-0.53 depending on combination of the variabilities in design parameters to be considered

  8. Enhancing service delivery capacity through knowledge exchange: the Seniors Health Research Transfer Network.

    Science.gov (United States)

    Conklin, James; Stolee, Paul; Luesby, Deirdre; Sharratt, Michael T; Chambers, Larry W

    2007-01-01

    The Seniors Health Research Transfer Network (SHRTN) was launched in 2005 in Ontario to improve the quality of health care provided to seniors by facilitating knowledge exchange opportunities for formal and informal caregivers, researchers and policymakers. This article describes the conceptual basis and development of SHRTN, as well as achievements, challenges and lessons learned during its first year of operation, which ended in March 2006. We begin by discussing knowledge exchange networks and their conceptual basis. We then offer a brief history of SHRTN, tracing its origins to both a broad interprofessional interest in creating and sharing knowledge within and across organizations, and also to the efforts of a small group of early champions. After this, we describe the main events, achievements and surprises of SHRTN's first year. Experience with SHRTN has highlighted the importance of careful attention to governance issues in the organization of knowledge exchange networks, and the challenge of balancing management control with broad participation and flexibility. Collaboration can yield synergy and innovation, but requires commitment from participants. The SHRTN experience has demonstrated that planning and coordinating a provincial network that engages diverse stakeholders is a logistical challenge that requires dedicated infrastructure and funding support. PMID:18399265

  9. Modelling of cation concentrations in the outflow of NaNO3 percolation experiments through Boom Clay cores

    International Nuclear Information System (INIS)

    A laboratory percolation experiment was performed to study the effect of a NaNO3 plume on the Boom Clay. In this experiment, Boom Clay cores were consecutively percolated with Boom Clay pore water and Boom Clay pore water to which NaNO3 was added. The concentration of NaNO3 in the pore water was increased stepwise (0.1, 0.5, and 1 M NaNO3). The concentrations of Na, K, Ca, Mg and Sr in the eluted water were measured. After every switch of the NaNO3 concentration, the concentration profiles of K, Ca, Mg, and Sr showed a sharp rise, followed by a slow decrease. It was hypothesised that the cation elution curves are mainly determined by cation exchange processes. Reactive coupled transport modelling with the PHREEQC-2 code was used to describe the experimentally observed elution curves for the cations. Solute transport and water-clay interaction mechanisms, namely cation exchange, were accounted for in the model. Cation exchange parameters (cation exchange capacity and selectivity coefficients) previously determined on non-perturbed Boom Clay (De Craen et al., 2004) were used. A sensitivity analysis was performed to assess the influence of these parameter values on the goodness of the model to describe the experimental data. The model could fairly well describe the experimentally observed cation concentrations in the eluted water, confirming that cation exchange is indeed the dominant mechanism regulating the cation elution in the percolation experiments. (authors)

  10. Recover of some rare earth elements from leach liquor of the Saghand uranium ore using combined precipitation and cation exchange methods

    International Nuclear Information System (INIS)

    In this research work, the recovery and separation of La(III), Ce(III), Sm(III), Dy(III) and Nd(III) from Saghand uranium ore have been studied by precipitation and ion-exchange chromatography methods using Dowex 50 W-X 8 cation exchanger. At first, some preliminary and preconcentration experiments such as comminution, sieve analysis, gravity table and electrostatic in preconcentration of lanthanides were performed. Then, acidic digesting and leaching procedure were used. The results of experiments showed that rare earth elements, along with interfering ions such as Al(III), Fe(III), Mg(II) and Mn(II) present in the leach liquor solution. The investigation of separation process by precipitation method revealed that precipitation and then fast separation using centrifugal technique had the best results in the elimination of interference elements. In order to separate the lanthanides and to obtain their elution curves, the chromatographic column containing Dowex 50 W-X 8 resin was employed. For efficient separation of lanthanides from interference elements the hydrochloric acid with concentration of two and six molar was used respectively. Recovery of lanthanides from the leach liquor solution was achieved more than 85%

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

    Directory of Open Access Journals (Sweden)

    A.A. Khan

    2011-10-01

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

  12. Effect of major cation water composition on the ion exchange of Np(V) on montmorillonite: NpO2+–Na+–K+–Ca2+–Mg2+ selectivity coefficients

    International Nuclear Information System (INIS)

    Highlights: • Determined Np(V)-montmorillonite ion exchange constant, applicable in a wide range of conditions. • Developed a model for Np(V) ion exchange which can be readily applied in thermodynamic databases. • Identified solution conditions at which Np(V) ion exchange will play a significant role. - Abstract: Np(V) sorption was examined in pH 4.5 colloidal suspensions of nominally homoionic montmorillonite (Na-, K-, Ca- and Mg-montmorillonite). Ionic exchange on permanent charge sites was studied as a function of ionic strength (0.1, 0.01 and 0.001 M) and background electrolyte (NaCl, KCl, CaCl2 and MgCl2). An ion exchange model was developed using the FIT4FD program, which considered all experimental data simultaneously: Np sorption data, major cation composition of the electrolyte and associated uncertainties. The model was developed to be consistent with the ion exchange selectivity coefficients between the major cations reported in the literature and led to the following recommended selectivity coefficients for Np(V) ion exchange according to the Vanselow convention: log(NpO2+Na+KV)=-0.20,log(NpO2+K+KV)=-0.46,log(NpO2+Ca2+KV)=-0.57,log (NpO2+Mg2+KV)=-0.57. Both the experimental data and the estimated selectivity coefficients in this study are consistent with the limited Np(V) ion exchange and sorption data reported in the literature. The results indicate that, as expected, low ionic strengths favor Np(V) sorption when ion exchange is the main sorption mechanism (i.e. acidic to neutral pHs) and that the divalent cations Ca2+ and Mg2+ may be important in limiting Np(V) ionic exchange on montmorillonite

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

    Science.gov (United States)

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

    2013-04-01

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

  14. Ion-exchange as a mode of cation transfer into room-temperature ionic liquids containing crown ethers : implications for the 'greenness' of ionic liquids as diluents in liquid-liquid extraction

    International Nuclear Information System (INIS)

    The transfer of strontium ion from acidic nitrate media into a series of 1-alkyl-3-methylimidazolium-based room-temperature ionic liquids containing dicyclohexano-18-crown-6 is shown to proceed via cation-exchange, in contrast to conventional solvents such as alkan-1-ols, in which extraction of a strontium nitrato-crown ether complex is observed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mosley, W.C.

    2001-09-17

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

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

    Science.gov (United States)

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

    1999-01-01

    Squalamine, an endogenous molecule found in the liver and other tissues of Squalus acanthias, has antibiotic properties and causes changes in endothelial cell shape. The latter suggested that its potential targets might include transport proteins that control cell volume or cell shape. The effect of purified squalamine was examined on cloned Na+/H+ exchanger isoforms NHE1, NHE2, and NHE3 stably transfected in PS120 fibroblasts. Squalamine (1-h pretreatment) decreased the maximal velocity of rabbit NHE3 in a concentration-dependent manner (13, 47, and 57% inhibition with 3, 5, and 7 micrograms/ml, respectively) and also increased K'[H+]i. Squalamine did not affect rabbit NHE1 or NHE2 function. The inhibitory effect of squalamine was 1) time dependent, with no effect of immediate addition and maximum effect with 1 h of exposure, and 2) fully reversible. Squalamine pretreatment of the ileum for 60 min inhibited brush-border membrane vesicle Na+/H+ activity by 51%. Further investigation into the mechanism of squalamine's effects showed that squalamine required the COOH-terminal 76 amino acids of NHE3. Squalamine had no cytotoxic effect at the concentrations studied, as indicated by monitoring lactate dehydrogenase release. These results indicate that squalamine 1) is a specific inhibitor of the brush-border NHE isoform NHE3 and not NHE1 or NHE2, 2) acts in a nontoxic and fully reversible manner, and 3) has a delayed effect, indicating that it may influence brush-border Na+/H+ exchanger function indirectly, through an intracellular signaling pathway or by acting as an intracellular modulator. PMID:9886929

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

    Science.gov (United States)

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

    2016-05-11

    The relationships among the macroscopic compositional parameters of a Cu-exchanged SSZ-13 zeolite catalyst, the types and numbers of Cu active sites, and activity for the selective catalytic reduction (SCR) of NOx with NH3 are established through experimental interrogation and computational analysis of materials across the catalyst composition space. Density functional theory, stochastic models, and experimental characterizations demonstrate that within the synthesis protocols applied here and across Si:Al ratios, the volumetric density of six-membered-rings (6MR) containing two Al (2Al sites) is consistent with a random Al siting in the SSZ-13 lattice subject to Löwenstein's rule. Further, exchanged Cu(II) ions first populate these 2Al sites before populating remaining unpaired, or 1Al, sites as Cu(II)OH. These sites are distinguished and enumerated ex situ through vibrational and X-ray absorption spectroscopies (XAS) and chemical titrations. In situ and operando XAS follow Cu oxidation state and coordination environment as a function of environmental conditions including low-temperature (473 K) SCR catalysis and are rationalized through first-principles thermodynamics and ab initio molecular dynamics. Experiment and theory together reveal that the Cu sites respond sensitively to exposure conditions, and in particular that Cu species are solvated and mobilized by NH3 under SCR conditions. While Cu sites are spectroscopically and chemically distinct away from these conditions, they exhibit similar turnover rates, apparent activation energies and apparent reaction orders at the SCR conditions, even on zeolite frameworks other than SSZ13. PMID:27070199

  18. Forest-soil response to acid and salt additions of sulfate. 2. Aluminum and base cations

    International Nuclear Information System (INIS)

    Reconstructed spodosol and intact alfisol soil columns were used to examine the effects of 52 weeks of additions of various simulated throughfall solutions on base cation, Al, acid neutralizing capacity, and pH levels in soil leachates. The work illustrates the importance of soil cation exchange (especially in the forest floor), anion concentrations, and pCO2 levels in controlling the leachate chemistry in response to acidic and 'seasalt' deposition events

  19. Onset of size independent cationic exchange in nano-sized CoFe{sub 2}O{sub 4} induced by electronic excitation

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Hemaunt [Department of Physics, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand 263145 (India); Singh, Jitendra Pal, E-mail: jitendra_singh2029@rediffmail.com [Advanced Analysis Canter, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Srivastava, R.C.; Negi, P.; Agrawal, H.M. [Department of Physics, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand 263145 (India); Asokan, Kandasami [Materials Science Division, Inter University Accelerator Centre, New Delhi 110067 (India); Won, Sung Ok [Advanced Analysis Canter, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Chae, Keun Hwa, E-mail: khchae@kist.re.kr [Advanced Analysis Canter, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)

    2015-10-05

    Highlights: • Electronic excitation induced crystalline order in CoFe{sub 2}O{sub 4}. • No change of metallic valence state under dense electronic excitation. • Size independent control of cations in CoFe{sub 2}O{sub 4}. - Abstract: Present work investigates electronic excitation induced cationic exchange phenomena in nano-sized cobalt ferrites using Mössabaur and X-ray absorption spectroscopies. The electronic excitations were produced by irradiation of 100 MeV O{sup +7} at different fluences ranging from 1 × 10{sup 11} to 1 × 10{sup 14} ions/cm{sup 2}. Cubic spinel phase of cobalt ferrite remains preserved after irradiation. However, attributes of crystalline disorder were observed in irradiated materials. Crystallite size remain almost same for pristine and irradiated materials. X-ray absorption fine structure measurements show the preservation of valence state and spin state of metal ions under intense electronic excitation. These measurements also envisage bond breaking process induced by the electronic excitation. Mössbauer spectroscopic measurements also corroborate with the fine structure measurements that the valence state of Fe remains same after irradiation. Paramagnetic doublet which presents in the Mössabaur spectrum of pristine material disappears after irradiation, showing the evolution of irradiation induced magnetic ordering. Fe{sup 3+} ion increases with irradiation at octahedral site of spinel lattice. Magnetization of the material slightly increases after irradiation at the fluence of 5 × 10{sup 13} and 1 × 10{sup 14} ions/cm{sup 2}.

  20. Influence of cation substitution and activator site exchange on the photoluminescence properties of Eu3+-doped quaternary pyrochlore oxides.

    Science.gov (United States)

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

    2013-12-01

    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

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

    DEFF Research Database (Denmark)

    Charalampidis, C.; Van As, D.; Box, J. E.;

    2015-01-01

    negative surface mass budget (SMB) and surface meltwater run-off. The observed run-off was due to a large ice fraction in the upper 10 m of firn that prevented meltwater from percolating to available pore volume below. Analysis reveals an anomalously low 2012 summer-averaged albedo of 0.71 (typically ∼ 0...... lowering resulted from high atmospheric temperatures, up to a +2.6 °C daily average, indicating that 2012 would have been a negative SMB year at this site even without the melt-albedo feedback. Longer time series of SMB, regional temperature, and remotely sensed albedo (MODIS) show that 2012 was the first...... strongly negative SMB year, with the lowest albedo, at this elevation on record. The warm conditions of recent years have resulted in enhanced melt and reduction of the refreezing capacity in the lower accumulation area. If high temperatures continue, the current lower accumulation area will turn into a...

  2. Lanthanide N,N'-piperazine-bis(methylenephosphonates) (Ln=La, Ce, Nd) that display flexible frameworks, reversible hydration and cation exchange

    International Nuclear Information System (INIS)

    Hydrothermal syntheses of lanthanide bisphosphonate metal organic frameworks comprising the light lanthanides lanthanum, cerium and neodymium and N,N'-piperazine bis(methylenephosphonic acid) (H2L(1) and its 2-methyl and 2,5-dimethyl derivatives (H2L(2) and H2L(3)) gives three new structure types. At elevated starting pH (ca. 5 and above) syntheses give 'type I' materials with all metals and acids of the study (MLnLxH2O, M=Na, K, Cs; Ln=La, Ce, Nd; x∼4: KCeL(1).4H2O, C2/c, a=23.5864(2) A, b=12.1186(2) A, c=5.6613(2) A, β=93.040(2)o). The framework of structure type I shows considerable flexibility as the ligand is changed, due mainly to rotation around the -N-CH2- bond of the linker in response to steric considerations. Type I materials demonstrate cation exchange and dehydration and rehydration behaviour. Upon dehydration of KCeL.4H2O, the space group changes to P21/n, a=21.8361(12) A, b=9.3519(4) A, c=5.5629(3) A, β=96.560(4)o, as a result of a change of the piperazine ring from chair to boat configuration. When syntheses are performed at lower pH, two other structure types crystallise. With the 'non-methyl' ligand 1, type II materials result (LnL(1)H2L(1).4.5H2O: Ln=La, P-1, a=5.7630(13) A, b=10.213(2) A, c=11.649(2) A, α=84.242(2)o, β=89.051(2)o, γ=82.876(2)o) in which one half of the ligands coordinate via the piperazine nitrogen atoms. With the 2-methyl ligand, structure type III crystallises (LnHL(2).4H2O: Ln=Nd, Ce, P21/c, a=5.7540(9) A, b=14.1259(18) A, c=21.156(5) A, β=90.14(2)o) due to unfavourable steric interactions of the methyl group in structure type II. - Graphical abstract: The lanthanides La, Ce and Nd give a family of metal organic frameworks based on N,N'-piperazinebismethylenephosphonate ligands: these display reversible dehydration, structural flexibility and cation exchange.

  3. The effect of degradation products of strong acidic cation exchange resins on radionuclide speciation: A case study with Ni2+

    International Nuclear Information System (INIS)

    Radiolytic degradation experiments with acidic ion-exchange resins revealed oxalate and an unidentified ligand X to be the most strongly complexing ligands of the degradation products. The influence of these ligands on the Ni speciation in groundwater and cement pore water of a repository is assessed. A complete and reliable thermodynamic database is built for this case study. Missing stability constants are estimated by chemical reasoning. Subsequent sensitivity analyses show whether these species are important or not. The backdoor approach used in this study addresses the following question: What concentrations must the ligand have to significantly influence the Ni speciation? In the case of oxalate, the concentration necessary to complex 90% Ni will never be exceeded within the repository or in its environment due to precipitation of Ca-oxalate solids. Thus, a negative effect of oxalate on Ni speciation and sorption need not be considered in safety assessments. In the case of ligand X, calculations demonstrate that Ni speciation is highly dependent on geochemical conditions and is occasionally ambiguous due to uncertainties in estimated stability constants. Hints are given to deal with these ambiguities in future safety assessment, and further experimental investigations are proposed to decrease uncertainties when necessary

  4. Actinide cation-cation complexes

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-26

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

  6. The influence of plutonium concentration and solution flow rate on the effective capacity of macroporous anion exchange resin

    International Nuclear Information System (INIS)

    The principal aqueous process used to recover and purify plutonium at the Los Alamos Plutonium Facility is anion exchange in nitric acid. Previous studies with gel-type anion exchange resin have shown an inverse relationship between plutonium concentration in the feed solution and the optimum flow rate for this process. Because gel-type resin has been replaced with macroporous resin at Los Alamos, the relationship between plutonium concentration and solution flow rate was reexamined with the selected Lewatit MP-500-FK resin using solutions of plutonium in nitric acid and in nitric acid with high levels of added nitrate salts. Our results with this resin differ significantly from previous data obtained with gel-type resin. Flow-rate variation from 10 to 80 liters per hour had essentially no effect on the measured quantities of plutonium sorbed by the macroporous resin. However, the effect of plutonium concentration in the feed solutions was pronounced, as feed solutions that contained the highest concentrations of plutonium also produced the highest resin loadings. The most notable effect of high concentrations of dissolved nitrate salts in these solutions was an increased resin capacity for plutonium at low flow rates. 16 refs., 7 figs., 2 tabs

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

    Science.gov (United States)

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

    2009-09-15

    In this study, a cation-exchange resin (CEX) of the K(+)-form, i.e., an enhancer resin, is used as a postcolumn conductimetric enhancer in the ion-exclusion chromatography of aliphatic carboxylic acids. The enhancer resin is filled in the switching valve of an ion chromatograph; this valve is usually used as a suppressor valve in ion-exchange chromatography. An aliphatic carboxylic acid (e.g., CH(3)COOH) separated by a weakly acidic CEX column of the H(+)-form converts into that of the K(+)-form (e.g., CH(3)COOK) by passing through the enhancer resin. In contrast, the background conductivity decreases because a strong acid (e.g., HNO(3)) with a higher conductimetric response in an eluent converts into a salt (e.g., KNO(3)) with a lower conductimetric response. Since the pH of the eluent containing the resin enhancer increases from 3.27 to 5.85, the enhancer accelerates the dissociations of analyte acids. Consequently, peak heights and peak areas of aliphatic carboxylic acids (e.g., acetic acid, propionic acid, butyric acid, and valeric acid) with the enhancer resin are 6.3-8.0 times higher and 7.2-9.2 times larger, respectively, than those without the enhancer resin. Calibrations of peak areas for injected analytes are linear in the concentration range of 0.01-1.0mM. The detection limits (signal-to-noise ratio=3) range from 0.10 microM to 0.39 microM in this system, as opposed to those in the range of 0.24-7.1 microM in the separation column alone. The developed system is successfully applied to the determination of aliphatic carboxylic acids in a chicken droppings sample. PMID:19615503

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-08-01

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

  9. Cation exchange-based post-processing of 68Ga-eluate: A comparison of three solvent systems for labelling of DOTATOC, NO2APBP and DATAm

    International Nuclear Information System (INIS)

    Interest in 68Ga has led to a number of innovations for its provision suitable for clinical application. Several post-processing methods are available to reduce eluate volume and remove metal trace impurities. In this work three cation exchange resin based post-processing methods (acetone, ethanol and NaCl) have been compared, using three model precursors (DOTATOC, NO2APBP and DATAm), in terms of labelling yield and reproducibility. The acetone and ethanol based methods provided greater reproducibility and yields that makes subsequent purification unnecessary. - Highlights: • Comparison of different 68Ga post-processing methods through the labelling of DOTATOC, NO2APBP and DATAm. • Comparison in terms of radiochemical yield, reproducibility and radiolysis. • Ethanol and acetone post-processed 68Ga facilitated the highest yields and reproducibility. • Ethanol post-processed 68Ga resulted in the lowest degree of radiolysis of 68Ga-DOTATOC. • Experimenting with different post-processing methods is an important optimisation step. • Ethanol-post processed 68Ga is suitable for clinical application

  10. Changing Surface-Atmosphere Energy Exchange and Refreezing Capacity of the Lower Accumulation Area, West Greenland

    Science.gov (United States)

    Charalampidis, C.; van As, D.; Machguth, H.; Smeets, P.; van den Broeke, M. R.; Box, J. E.

    2014-12-01

    We present five years (2009-2013) of automatic weather station (AWS) data from the lower accumulation area (1840 m above sea level) of the Kangerlussuaq region, western Greenland ice sheet. The summers of 2010 and 2012 were both exceptionally warm, but only 2012 resulted in negative surface mass budget (SMB) and surface runoff. The observed runoff was due to a large ice fraction in the upper 10 m of firn that prevented melt water from percolating to available pore space below. Analysis of the in situ data reveals a relatively low 2012 summer albedo of ~0.7 as melt water was present at the surface. Consequently, during the 2012 melt season the surface absorbed 30% (213 MJ m-2) more solar radiation than in 2010. We drive a surface energy balance model with the AWS data to evaluate the seasonal and interannual variability of all surface energy fluxes. The model is able to reproduce the observed melt rates as well as the SMB for each season. While the drive for melt is solar radiation, year-to-year differences are controlled by terrestrial radiation, apart from 2012 when solar radiation dominated melt. Sensitivity tests reveal that 72% of the excess solar energy in 2012 was used for melt, corresponding to 40% (0.67 m) of the 2012 surface ablation. The remaining ablation (0.99 m) was primarily due to the relatively high atmospheric temperatures up to +2.6 °C daily average, indicating that 2012 would have been a negative SMB year in the lower accumulation area even without the melt-albedo feedback. Longer time series of SMB, regional temperature and remotely sensed albedo (MODIS) suggest that 2012 was the first negative SMB year with the lowest albedo at this elevation on record. The warming conditions of the last years resulted in enhanced melt and reduction of the refreezing capacity of the lower accumulation area. If the warming continues the lower accumulation area will be transformed into superimposed ice.

  11. Synthesis and characterization of a new cation exchanger-zirconium(IV)iodotungstate: Separation and determination of metal ion contents of synthetic mixtures, pharmaceutical preparations and standard reference material

    International Nuclear Information System (INIS)

    Samples of zirconium(IV)iodotungstate have been synthesized under varying mixing order and ratios of aqueous solution of potassium iodate, sodium tungstate and zirconium oxychloride at pH 1. A tentative formula was proposed on the basis of chemical composition, FTIR and thermogravimetric studies. The material shows a capacity of 0.68 meq g-1 (for K+) which can be retained up to 200 deg. C. pH titration data reveal its monofunctional behavior. The distribution coefficient values of metal ions have been determined in various solvent systems. A number of important and analytically difficult quantitative separations of metal ions have been achieved using columns packed with this exchanger. In order to demonstrate practical utility of this material, Hg2+ and Pb2+ have been selectively separated and determined in the synthetic mixtures. Assay of Al3+ and Mg2+ in commercial tablets and analysis of lead in the standard reference material have also been attempted.

  12. Utilizing full-exchange capacity of zeolites by alkaline leaching: Preparation of Fe-ZSM5 and application in N2O decomposition

    OpenAIRE

    Melian-Cabrera, [No Value; Espinosa, S.; Linden, B. van der; Kapteijn, F.; Moulijn, JA; Melián-Cabrera, I.; Linden, B. v/d; Groen, J.C.

    2006-01-01

    Utilization of the full exchange capacity of zeolites has been achieved by shortening diffusional lengths on a mild alkaline leaching treatment. Iron was fully incorporated by liquid-phase, ion exchange on ZSM5 without the formation of Fe-oxides, leading to improved activity in the N2O-exchange decomposition reaction. It is demonstrated that the large crystal size of the zeolite dominates the Fe-III-process. The crystallinity of the ZSM5 zeolite can be tuned down by postsynthesis modification...

  13. A novel approach to measure elemental concentrations in cation exchange resins using XRF-scanning technique, and its potential in water pollution studies

    Science.gov (United States)

    Huang, Jyh-Jaan; Lin, Sheng-Chi; Löwemark, Ludvig; Liou, Ya-Hsuan; Chang, Queenie; Chang, Tsun-Kuo; Wei, Kuo-Yen; Croudace, Ian W.

    2016-04-01

    X-ray fluorescence (XRF) core-scanning is a fast, and convenient technique to assess elemental variations for a wide variety of research topics. However, the XRF scanning counts are often considered a semi-quantitative measurement due to possible absorption or scattering caused by down core variability in physical properties. To overcome this problem and extend the applications of XRF-scanning to water pollution studies, we propose to use cation exchange resin (IR-120) as an "elemental carrier", and to analyze the resins using the Itrax-XRF core scanner. The use of resin minimizes the matrix effects during the measurements, and can be employed in the field in great numbers due to its low price. Therefore, the fast, and non-destructive XRF-scanning technique can provide a quick and economical method to analyze environmental pollution via absorption in the resin. Five standard resin samples were scanned by the Itrax-XRF core scanner at different exposure times (1 s, 5 s, 15 s, 30 s, 100 s) to allow the comparisons of scanning counts with the absolute concentrations. The regression lines and correlation coefficients of elements that are generally used in pollution studies (Ca, Ti, Cr, Ni, Cu, Zn, and Pb) were examined for the different exposure times. The result shows that within the test range (from few ppm to thousands ppm), the correlation coefficients are all higher than 0.97, even at the shortest exposure time (1 s). Therefore, we propose to use this method in the field to monitor for example sewage disposal events. The low price of resin, and fast, multi elements and precise XRF-scanning technique provide a viable, cost- and time-effective approach that allows large sample numbers to be processed. In this way, the properties and sources of wastewater pollution can be traced for the purpose of environmental monitoring and environmental forensics.

  14. CATION EXCHANGER1 Cosegregates with Cadmium Tolerance in the Metal Hyperaccumulator Arabidopsis halleri and Plays a Role in Limiting Oxidative Stress in Arabidopsis Spp.

    Science.gov (United States)

    Baliardini, Cecilia; Meyer, Claire-Lise; Salis, Pietrino; Saumitou-Laprade, Pierre; Verbruggen, Nathalie

    2015-09-01

    Arabidopsis halleri is a model species for the study of plant adaptation to extreme metallic conditions. In this species, cadmium (Cd) tolerance seems to be constitutive, and the mechanisms underlying the trait are still poorly understood. A previous quantitative trait loci (QTL) analysis performed on A. halleri × Arabidopsis lyrata backcross population1 identified the metal-pump gene Heavy Metal ATPase4 as the major genetic determinant for Cd tolerance. However, although necessary, Heavy Metal ATPase4 alone is not sufficient for determining this trait. After fine mapping, a gene encoding a calcium(2+)/hydrogen(+) antiporter, cation/hydrogen(+) exchanger1 (CAX1), was identified as a candidate gene for the second QTL of Cd tolerance in A. halleri. Backcross population1 individuals displaying the A. halleri allele for the CAX1 locus exhibited significantly higher CAX1 expression levels compared with the ones with the A. lyrata allele, and a positive correlation between CAX1 expression and Cd tolerance was observed. Here, we show that this QTL is conditional and that it is only detectable at low external Ca concentration. CAX1 expression in both roots and shoots was higher in A. halleri than in the close Cd-sensitive relative species A. lyrata and Arabidopsis thaliana. Moreover, CAX1 loss of function in A. thaliana led to higher Cd sensitivity at low concentration of Ca, higher sensitivity to methylviologen, and stronger accumulation of reactive oxygen species after Cd treatment. Overall, this study identifies a unique genetic determinant of Cd tolerance in the metal hyperaccumulator A. halleri and offers a new twist for the function of CAX1 in plants. PMID:26162428

  15. CATION EXCHANGER1 Cosegregates with Cadmium Tolerance in the Metal Hyperaccumulator Arabidopsis halleri and Plays a Role in Limiting Oxidative Stress in Arabidopsis Spp.1[OPEN

    Science.gov (United States)

    Baliardini, Cecilia; Meyer, Claire-Lise; Salis, Pietrino; Saumitou-Laprade, Pierre; Verbruggen, Nathalie

    2015-01-01

    Arabidopsis halleri is a model species for the study of plant adaptation to extreme metallic conditions. In this species, cadmium (Cd) tolerance seems to be constitutive, and the mechanisms underlying the trait are still poorly understood. A previous quantitative trait loci (QTL) analysis performed on A. halleri × Arabidopsis lyrata backcross population1 identified the metal-pump gene Heavy Metal ATPase4 as the major genetic determinant for Cd tolerance. However, although necessary, Heavy Metal ATPase4 alone is not sufficient for determining this trait. After fine mapping, a gene encoding a calcium2+/hydrogen+ antiporter, cation/hydrogen+ exchanger1 (CAX1), was identified as a candidate gene for the second QTL of Cd tolerance in A. halleri. Backcross population1 individuals displaying the A. halleri allele for the CAX1 locus exhibited significantly higher CAX1 expression levels compared with the ones with the A. lyrata allele, and a positive correlation between CAX1 expression and Cd tolerance was observed. Here, we show that this QTL is conditional and that it is only detectable at low external Ca concentration. CAX1 expression in both roots and shoots was higher in A. halleri than in the close Cd-sensitive relative species A. lyrata and Arabidopsis thaliana. Moreover, CAX1 loss of function in A. thaliana led to higher Cd sensitivity at low concentration of Ca, higher sensitivity to methylviologen, and stronger accumulation of reactive oxygen species after Cd treatment. Overall, this study identifies a unique genetic determinant of Cd tolerance in the metal hyperaccumulator A. halleri and offers a new twist for the function of CAX1 in plants. PMID:26162428

  16. Functionalized alkynyl-chlorogermanes: hydrometallation, Ge-Cl bond activation, Ge-H bond formation and chlorine-tert-butyl exchange via a transient germyl cation.

    Science.gov (United States)

    Honacker, Christian; Qu, Zheng-Wang; Tannert, Jens; Layh, Marcus; Hepp, Alexander; Grimme, Stefan; Uhl, Werner

    2016-04-14

    Treatment of alkynyl-arylchlorogermanes ArylnGe(Cl)(C[triple bond, length as m-dash]C-(t)Bu)3-n (n = 1, 2) with HM(t)Bu2 (M = Al, Ga) yielded mixed Al or Ga alkenyl-alkynylchlorogermanes via hydrometallation reactions. Intramolecular interactions between the Lewis-basic Cl atoms and the Lewis-acidic Al or Ga atoms afforded MCGeCl heterocycles. The endocyclic M-Cl distances were significantly lengthened compared to the starting compounds and indicated Ge-Cl bond activation. Dual hydrometallation succeeded only with HGa(t)Bu2. One Ga atom of the product was involved in a Ga-Cl bond, while the second one had an interaction to a C-H bond of a phenyl group. In two cases treatment of chlorogermanes with two equivalents of HAl(t)Bu2 resulted in hydroalumination of one alkynyl group and formation of unprecedented Ge-H functionalized germanes, Aryl-Ge(H)(C[triple bond, length as m-dash]C-(t)Bu)[C(Al(t)Bu2)[double bond, length as m-dash]C(H)-(t)Bu] (Aryl = mesityl, triisopropylphenyl). The Al atoms of these compounds interacted with the α-C atoms of the alkynyl groups. Ph(Cl)Ge(C[triple bond, length as m-dash]C-(t)Bu)[C(Al(t)Bu2}[double bond, length as m-dash]C(H)-(t)Bu] reacted in an unusual Cl/(t)Bu exchange to yield the tert-butylgermane Ph((t)Bu)Ge(C[triple bond, length as m-dash]C-(t)Bu)[C{Al((t)Bu)(Cl)}[double bond, length as m-dash]C(H)-(t)Bu]. Quantum chemical calculations suggested the formation of a germyl cation as a transient intermediate. PMID:26610394

  17. Preparation, properties and ion-exchange behavior of stannic silicomolybdate

    International Nuclear Information System (INIS)

    The ion-exchange properties of stannic silicomolybdate were studied using the batch method. Preparation of stannic silicomolybdate is shown. The sorbent is stable in water and diluted mineral acids. X-ray diffraction study shows amorphous structure and chemical analysis was performed. The ion-exchange capacities for alkali metals and strontium cations were determined by using fotometric measurements and chemical analyses of the equilibrated exchangers by atomic absorption. The tow techniques showed similar results which revealed that the capacities was changed in values and orders with the changing of the preparation method of the exchangers. The exchangers showed high selectivity for cesium and strontium cations. The results showed decreasing of Kd with increasing of the concentration of ion-exchanger. Also the effect of nitrate anions was investigated by studying the distribution coefficients in nitrate media. The results showed that nitrate anion from nitric acid or ammonium nitrate, led to decrease the distribution coefficients. The results obtained reveal that the properties of the exchangers is slightly changed with the change of the conditions of preparation but the general behaviour of Cs+ and Sr++ cations almost remain the same. Also nitrate solution can be used to reextract these cations from the exchangers. 4 tabs

  18. Chemical studies on polyaniline titanotungstate as a new composite cation exchanger and its analytical applications for removal of cesium from aqueous solutions

    International Nuclear Information System (INIS)

    Polyaniline titanotungstate has been synthesized by incorporation of organic polymer polyaniline into the inorganic precipitate of titanotungstate. This material was characterized using IR, X-Ray, SEM and DTA-TGA analysis. The influences of initial concentration of metal ions, particle size and temperature have been reported. The material stability was investigated in water, acids, alkaline solutions, and at high temperature up to 850 degree C. Ion-exchange capacity and distribution coefficients (Kd) for ten metal ions have been determined. It was found that the polyaniline titanotungstate has high affinity and high selectivity for Cs+. The material has high separation for Cs+ ion from other metal ions. The comparison of composite (PATiW) and inorganic material (TiW) was studied and indicated that the composite material is better than the inorganic one in selectivity of Cs+. Thermodynamic parameter of Cs+ exchange process, such as changes in Gibbs free energy (δGo), enthalpy (δHo), and entropy (δSo) have been calculated. It was found that numerical value of δG decrease with an increase in temperature,indicating that the sorption reaction of adsorbent was spontaneous and more favorable at higher temperature. The positive value of δHo corresponds to the endothermic nature of sorption processes and suggested that chemisorptions were the predominant mechanism. A comparison of kinetic models applied to the sorption rate data of Cs+ was evaluated for the pseudo first-order, pseudo second-order, homogeneous particle diffusion, shell model and intraparticle diffusion models. The results showed that Cs+ is sorption onto PATiW and TiW with particle diffusion mechanism. Self diffusion coefficient (Di), Activation energy (Ea) and entropy (δS*) of activation were also computed from thelinearized form of Arrhenius equation. Column studies in acid and alkaline solutions were studied. A kinetic study for removal cesium from milk was investigated.

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

    International Nuclear Information System (INIS)

    A new adsorbent (PGCP-COOH) having carboxylate functional group at the chain end was synthesized by grafting poly(hydroxyethylmethacrylate) onto coconut coir pith, CP (a coir industry-based lignocellulosic residue), using potassium peroxydisulphate as an initiator and in the presence of N,N'-methylenebisacrylamide as a cross-linking agent. The adsorbent was characterized with the help of infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and potentiometric titrations. The ability of PGCP-COOH to remove Hg(II) from aqueous solutions was assessed using batch adsorption technique under kinetic and equilibrium conditions. Adsorbent exhibits very high adsorption potential for Hg(II) and more than 99.0% removal was achieved in the pH range 5.5-8.0. Adsorption process was found to follow first-order-reversible kinetics. An increase of ionic strength of the medium caused a decrease in metal removal, indicating the occurrence of outer-sphere surface complex mechanism. The equilibrium data were fitted well by the Freundlich isotherm model (R2 = 0.99; χ2 1.81). The removal efficiency was tested using chlor-alkali industry wastewater. Adsorption isotherm experiments were also conducted for comparison using a commercial carboxylate-functionalized ion exchanger, Ceralite IRC-50. Regeneration experiments were tried for four cycles and results indicate a capacity loss of <9.0%

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

    KAUST Repository

    Chubar, Natalia

    2011-12-01

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

  1. A versatile reversed phase-strong cation exchange-reversed phase (RP-SCX-RP) multidimensional liquid chromatography platform for qualitative and quantitative shotgun proteomics.

    Science.gov (United States)

    Law, Henry C H; Kong, Ricky P W; Szeto, Samuel S W; Zhao, Yun; Zhang, Zaijun; Wang, Yuqiang; Li, Guohui; Quan, Quan; Lee, Simon M Y; Lam, Herman C; Chu, Ivan K

    2015-02-21

    An automatable, robust, high-performance online multidimensional liquid chromatography (MDLC) platform comprising of pH 10 reversed-phase (RP), strong cation exchange (SCX), and pH 2 RP separation stages has been integrated into a modified commercial off-the-shelf LC instrument with a simple rewiring, enabling accelerated routine qualitative and quantitative proteomics analyses. This system has been redesigned with a dual-trap column configuration to improve the throughput by greatly decreasing the system idle time. The performance of this new design has been benchmarked through analysis of the total lysate of S. cerevisiae, in comparison with that of the former tailor-made system featuring more complicated components; the total run time per "load-and-go" LC/MS analysis was approximately 24 h, with minimal idle time and no labor-intensive steps. This platform features high-resolution fractionations, ease of use and a high degree of user programmability in the first two chromatographic dimensions, allowing flexible and effective sampling with (RP-SCX-RP) or without (RP-RP) the inclusion of SCX sub-fractionation; good proteome coverage and reproducibility was demonstrated through the analyses of bacterial, cell culture, and monkey brain tissue proteomes. The viability of the 3D RP-SCX-RP has been proven in proteome-wide studies of STO fibroblasts and yeast tryptic digests, resulting in extended proteome and protein coverages with high reproducibility-in particular, discovering extra-hydrophilic peptides-at the expense of the acquisition time. The identified inventory of the rat pheochromocytoma PC12 cell proteome-a total of 6345 proteins and 97 309 unique peptides is the most comprehensive dataset to date-provides an example of the value of the 3D RP-SCX-RP. The use of orthogonal chromatographic dimensions in the 3D RP-SCX-RP also circumvents the issues of isobaric interference of mass-tagging background contaminations, while significantly improving the accuracy of

  2. Tandem anion and cation exchange solid phase extraction for the enrichment of micropollutants and their transformation products from ozonation in a wastewater treatment plant.

    Science.gov (United States)

    Deeb, Ahmad A; Schmidt, Torsten C

    2016-06-01

    The presence of organic micropollutants and their transformation products (TPs) from biotic and abiotic processes in aquatic environments is receiving intense public and scientific attention. Yet a suitable sample preparation method that would enable extraction and enrichment of a wide range of such compounds from water is missing. The focus of this paper was to develop an enhanced solid phase extraction (SPE) protocol which enabled isolation of parent compounds and low molecular weight transformation products (that are produced after treatment of water with ozone) from different water matrices. Ten SPE sorbents were evaluated with regard to their ability to extract acidic, neutral, and basic compounds from water at several pH values. Highest recoveries (91-99 %) for all analytes in pure water were obtained by combining strong anion and cation exchangers of two manufacturers in a tandem mode without pH adjustment. Tandem Oasis (MAX+MCX) was finally applied to extract the spiked analytes from tap water, surface water, and several wastewater samples. The efficiency of the used SPE procedure was examined using an optimized liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method using multiple reaction monitoring (MRM) mode. The occurrence of some of the investigated TPs in environmental water matrices was proven for the first time in this study. Method quantification limits (MQLs) for all compounds ranged from 3.7 to 15.3 ng/L in all matrices. Recoveries (%RE) were between 90 and 110 %. Intraday and interday precision, expressed as relative standard deviation, varied from 0.7 to 5.9 % and 1.8 to 10.3 %, respectively. Matrix effect (%ME) evaluation demonstrated that even complex sample matrices did not show significant ion suppression or enhancement. The applicability of the method was shown during two sampling campaigns at Ruhr river and a wastewater treatment plant (WWTP) equipped with an ozonation step after regular

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

    Science.gov (United States)

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

    2011-01-01

    We developed an ion-exclusion/adsorption chromatography (IEAC) method employing a polystyrene-divinylbenzene-based weakly acidic cation-exchange resin (PS-WCX) column with propionic acid as the eluent for the simultaneous determination of multivalent aliphatic carboxylic acids and ethanol in food samples. The PS-WCX column well resolved mono-, di-, and trivalent carboxylic acids in the acidic eluent. Propionic acid as the eluent gave a higher signal-to-noise ratio, and enabled sensitive conductimetric detection of analyte acids. We found the optimal separation condition to be the combination of a PS-WCX column and 20-mM propionic acid. Practical applicability of the developed method was confirmed by using a short precolumn with a strongly acidic cation-exchange resin in the H(+)-form connected before the separation column; this was to remove cations from food samples by converting them to hydrogen ions. Consequently, common carboxylic acids and ethanol in beer, wine, and soy sauce were successfully separated by the developed method. PMID:21558657

  4. Cesium exchange reaction on natural and modified clinoptilolite zeolites

    International Nuclear Information System (INIS)

    Cesium cation exchange reaction with K, Na, Ca and Mg ions on natural and modified clinoptilolite has been studied. Batch cation-exchange experiments were performed by placing 0.5 g of clinoptilolite into 10 ml or 20 ml of 1 x 10-3M CsCl solution for differing times. Two type deposits of clinoptilolite zeolites from, Nizny Hrabovec (NH), Slovakia and Metaxades (MX), Greece were used for ion-exchange study. The distribution coefficient (Kd) and sorption capacity (Γ) were evaluated. For the determination of K, Na, Ca and Mg isotachophoresis method, the most common cations in exchange reaction was used. Cesium sorption was studied using 137Cs tracer and measured by γ-spectrometry. (author)

  5. Synthesis, characterization and ion exchange properties of a new inorganic ion exchange material: zirconium(IV) iodooxalate

    International Nuclear Information System (INIS)

    A new three component inorganic ion exchange material zirconium (IV) iodooxalate (ZIO) has been synthesized by adding a mixture of O.1M potassium iodate and O.1M oxalic acid to O.1M zirconium oxychloride in different volume ratios at pH 1. Among several samples synthesized, ZIO-6 is selected for detailed studies owing to its highest ion exchange capacity and chemical stability. The material has been characterized on the basis of chemical composition, pH-titration, FTIR and thermogravimetric studies. The ion exchange capacity of the material for Na+ ion has been found to be 2.70 meq g-l dry exchanger. The ion exchange capacity varies and is found to depend upon the crystal ionic radius of exchanging cations. The chemical stability of the material has been tested in acidic, neutral and basic media. The sorption studies of some metal ions have been made in distilled water and nitric acid. (author)

  6. The mechanism of ion exchange on ammonium 12-molybdophosphate (AMP)

    International Nuclear Information System (INIS)

    This paper reviews some published and unpublished data on the ion-exchange properties of AMP. The three NH4+ ions are only partially exchanged for large monovalent ions. In the case of NH4+/K+ exchange, the energy lost by the breaking of H bonds between the NH4+ ions and anionic cage oxygen atoms beyond the point of maximum exchange is no longer compensated for by bond strengthening in the anion due to contraction of the cage. With Rb+, Cs+ and T1+, limited convertibility results from the lattice expansion required to accommodate these larger ions. During exchange, part of the cations pass through the anionic cages, thereby causing considerable lattice disorder. The maximum exchange capacity of AMP for the alkali metal ions is not a simple function of cation radius. (author)

  7. Determination of the antioxidant capacity of culinary herbs subjected to various cooking and storage processes using the ABTS(*+) radical cation assay.

    Science.gov (United States)

    Chohan, Magali; Forster-Wilkins, Gary; Opara, Elizabeth I

    2008-06-01

    Culinary herbs have the potential to be a significant source of antioxidants in the diet. However, many culinary herbs are cooked or undergo some other form of processing before they are consumed as part of a meal and such factors may affect their significance as a source of dietary antioxidants. Thus, the impact of cooking (simmering, microwaving, stewing, stir frying and grilling) and storage (vinegar maceration, cold maceration and freezing) on the antioxidant capacity of common culinary herbs was investigated. Extracts of cinnamon, cloves, fennel, ginger, lavender, parsley, rose, rosemary, sage and thyme were prepared pre and post cooking or storage and their antioxidant capacities determined using the Trolox equivalent antioxidant capacity assay (TEAC). Simmering, soup making and stewing significantly increased antioxidant capacity, whilst grilling and stir frying decreased it. Both freezing herbs at -20 degrees C and cold maceration had preservative effects on antioxidant capacity. Herbs in cold vinegar macerations for 1 week showed a decrease in antioxidant capacity compared to the control extracts. These results indicate that the potential of culinary herbs to be significant contributors to dietary antioxidant intake is significantly affected by both cooking and storage. PMID:18224444

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

    Science.gov (United States)

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

    2012-08-17

    A simple ion chromatographic method for simultaneous detection of iodide and iodate in a single running was proposed, with columns packed with homemade functionalized polystyrene-divinylbenzene (PS-DVB) resins and column-switching technique. Homemade resins were functionalized with controllable amounts of quaternary ammonium groups. The low-capacity anion-exchange column and high-capacity anion-exchange column were prepared, due to the resins having different exchange capacities. With this method, iodide and iodate in povidone iodine solution were detected simultaneously in a short time with iodide being eluted off first. A series of standard solutions consisting of target anions of various concentrations from 0.01 mg/L to 100 mg/L were analyzed. Each anion exhibited satisfactory linearity, with correlation coefficient r ≥ 0.9990. The detection limits (LODs) for iodide and iodate obtained by injecting 100 μL of sample were 5.66 and 14.83 μg/L (S/N=3), respectively. A spiking study was performed with satisfactory recoveries between 101.2% and 100.6% for iodide and iodate. PMID:22771256

  9. Molecular Simulation of Hydrogen Storage in Ion-Exchanged X Zeolites

    OpenAIRE

    Xiaoming Du

    2014-01-01

    Grand Canonical Monte Carlo (GCMC) method was employed to simulate the adsorption properties of molecular hydrogen on ion-exchanged X zeolites at 100–293 K and pressures up to 10 MPa in this paper. The effect of cation type, temperature, and pressure on hydrogen adsorption capacity, heat of adsorption, adsorption sites, and adsorption potential energy of ion-exchanged X zeolites was analyzed. The results indicate that the hydrogen adsorption capacity increases with the decrease in temperature...

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

    Energy Technology Data Exchange (ETDEWEB)

    Amer Amezaga, S.

    1963-07-01

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

  11. The determination of adsorption capacity of anion exchange resin Dowex-Marathon for Ti(IV) and Fe(III) chlorocomplexes

    International Nuclear Information System (INIS)

    Full text: The adsorption capacity of anion exchange resin Dowex-Marathon for Ti(IV) and Fe(III) chlorocomplexes from HCl solution was determined. The measurements were performed for different HCl solution concentrations and temperatures using batch operation as contact method between solution and resin. The Fe(III) adsorption capacities increased with HCl solution concentrations and contact temperatures. In the case of Ti(IV) considerable adsorption capacities were observed only at HCl concentrations >7 M. For the same ion the adsorption capacity does not depend on temperature in the range of 30 - 70 deg C. At 50 deg C there is an important difference between adsorption capacity for Fe(III), (105.7 mg Fe/g dry resin) and for U(VI), (227 mg U/g dry resin), allowing the recovery of uranium adsorption band in the 235U enriching column, using band displacement technique. A solution of TiCl3 0.1 M in HCl >7 M can be utilized as reduction agent at the rear edge of the uranium band, according to the important adsorption capacity of Ti(IV) in those conditions. (author)

  12. Effective removal of uranium ions from drinking water using CuO/X zeolite based nanocomposites. Effects of nano concentration and cation exchange

    International Nuclear Information System (INIS)

    For the first time, effects of CuO nanoparticles concentration (from 1 to 24.2 wt%) in CuO/NaX nanocomposite and replacing various cations (Ag+, K+, Ca2+, and Mg2+) with Na+ ions in NaX zeolite on removal of uranium ions from drinking water are reported. The removal of uranium was performed under natural conditions of pH, laboratory temperature and the presence of competing cations and anions that are available in tap water of Isfahan city. Characterization of parent NaX zeolite and modified samples were investigated using X-ray fluorescence, X-ray powder diffraction patterns, scanning electron microscopy, and atomic absorption spectroscopy methods. Using Langmuir, Freundlich, and C-models, isotherms of equilibrium adsorption were studied. Results show the removal efficiency and distribution coefficient of NaX zeolite decrease in the presence of other competing anions and cations that exist in drinking water. But, modification of NaX zeolite with various cations and CuO nanoparticles might enhance the ability of X zeolite in removing uranium from drinking water. (author)

  13. Sulfometuron incorporation in cationic micelles adsorbed on montmorillonite.

    Science.gov (United States)

    Mishael, Yael Golda; Undabeytia, Tomas; Rytwo, Giora; Papahadjopoulos-Sternberg, Brigitte; Rubin, Baruch; Nir, Shlomo

    2002-05-01

    The aim of this study was to understand the interactions between alkylammonium cations present as monomers and micelles and a clay mineral, montmorillonite, to develop slow release formulations of anionic herbicides, such as sulfometuron (SFM) whose leaching in soils is an environmental and economic problem. In the proposed formulation the herbicide is incorporated in positively charged micelles of quaternary amine cations, which in turn adsorb on the negatively charged clay. The adsorption of hexadecyltrimethylammonium (HDTMA) and octadecyltrimethylammonium (ODTMA) on montmorillonite was studied above and below their critical micelle concentrations (CMC). At concentrations above the CMC, the loading exceeded the clay's cation exchange capacity (CEC) and indicated higher affinity of the cation with the longer alkyl chain. An adsorption model could adequately simulate adsorption at concentrations below the CMC, and yield fair predictions for the effect of ionic strength. The model indicated that above the CMC adsorbed micelles contributed significantly to the amount of ODTMA adsorbed. Evidence for adsorption of ODTMA micelles on montmorillonite was provided by X-ray diffraction, freeze-fracture electron microscopy, and dialysis bag measurements. SFM was not adsorbed directly on the clay mineral, and adsorbed at low levels, when the organic cation was adsorbed as monomers. In contrast, a large fraction of SFM adsorbed on the clay mineral when incorporated in micelles that adsorbed on the clay. PMID:11982411

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

    Science.gov (United States)

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

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

    NARCIS (Netherlands)

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

    2001-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    Muhammad Nadeem Asghar; Qadeer Alam; Sharoon Augusten

    2012-01-01

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

  17. COMPARISON OF DRY DEPOSITION AND CANOPY EXCHANGE OF BASE CATIONS IN TEMPERATE HARDWOOD FORESTS IN FLANDERS AND CHILE ESTUDIO COMPARATIVO DE LA DEPOSITACION SECA E INTERCAMBIO EN EL DOSEL DE LOS CATIONES DE BASE EN BOSQUES TEMPLADOS DE FLANDERS Y CHILE

    Directory of Open Access Journals (Sweden)

    Jeroen Staelens

    2003-01-01

    Full Text Available Bulk precipitation, throughfall and stemflow of base cations Na+, K+, Mg2+ and Ca2+ were measured in two deciduous beech forests, located in regions with different air pollution characteristics and strongly differing in soil acidity and soil base saturation. The contribution of dry deposition and canopy leaching to net throughfall flux was estimated using Na+ as a tracer ion. The input of base cations via bulk precipitation was not significantly different between Nothofagus obliqua (Mirb. Bl. in southern Chile and Fagus sylvatica L. in Flanders. However, net throughfall input of Ca2+ and Mg2+ to the forest floor was significantly higher in Chile than in Flanders. Potassium fluxes were similar in both studied stands. Dry deposition of Ca2+ was higher in Chile, in absolute value as well as in relative contribution to net throughfall flux. A strong difference between the two Fagaceae-dominated forests was found for magnesium. In Chile, canopy leaching of Mg2+ (8.9 kg ha-1 y-1 was the major input source to the forest floor, while Mg2+ canopy leaching was close to zero in Flanders. As the availability of base cations in the soil solution determines the possibility of trees to exchange cations, we hypothesize that the lower Mg2+ canopy leaching in Flanders is mainly due to magnesium deficiency in the Flemish forest soilSe midieron las concentraciones de los cationes de base Na+, K+, Mg2+ y Ca2+ en la precipitación incidente, precipitación directa y escurrimiento fustal en dos bosques deciduos, localizados en regiones con diferente contaminación atmosférica, acidez del suelo y saturación de bases. La contribución de la depositación seca y el lavado del dosel en la precipitación efectiva se estimó utilizando el Na+ como un ion trazador. El ingreso de cationes de base vía precipitación incidente no fue significativamente diferente entre Nothofagus obliqua (Mirb. Bl. en el sur de Chile y Fagus sylvatica L. en Flanders. Sin embargo, las entradas

  18. 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

    International Nuclear Information System (INIS)

    Micaceous vermiculite was found to be ubiquitous in soils, sediments, and aerosol mineral dusts and to adsorb fission product ions, particularly 137Cs+ and 90Sr2+. Crystallographic wedge zones (imaged by ultramicrotomy and electron microscopy) in micaceous vermiculite effected tight fixation of Cs+. 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 NaNO3. 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 μm diameter). Mass spectrometry of its 18O/16O isotopic ratios showed distinctly higher (delta18O = 17 to 22%0) and lower (delta18O = 9 to 15%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

  19. Huntingtin regulates Ca(2+) chemotaxis and K(+)-facilitated cAMP chemotaxis, in conjunction with the monovalent cation/H(+) exchanger Nhe1, in a model developmental system: insights into its possible role in Huntington׳s disease.

    Science.gov (United States)

    Wessels, Deborah; Lusche, Daniel F; Scherer, Amanda; Kuhl, Spencer; Myre, Michael A; Soll, David R

    2014-10-01

    Huntington׳s disease is a neurodegenerative disorder, attributable to an expanded trinucleotide repeat in the coding region of the human HTT gene, which encodes the protein huntingtin. These mutations lead to huntingtin fragment inclusions in the striatum of the brain. However, the exact function of normal huntingtin and the defect causing the disease remain obscure. Because there are indications that huntingtin plays a role in Ca(2+) homeostasis, we studied the deletion mutant of the HTT ortholog in the model developmental system Dictyostelium discoideum, in which Ca(2+) plays a role in receptor-regulated behavior related to the aggregation process that leads to multicellular morphogenesis. The D. discoideum htt(-)-mutant failed to undergo both K(+)-facilitated chemotaxis in spatial gradients of the major chemoattractant cAMP, and chemotaxis up a spatial gradient of Ca(2+), but behaved normally in Ca(2+)-facilitated cAMP chemotaxis and Ca(2+)-dependent flow-directed motility. This was the same phenotypic profile of the null mutant of Nhel, a monovalent cation/H(+)exchanger. The htt(-)-mutant also failed to orient correctly during natural aggregation, as was the case for the Nhel mutant. Moreover, in a K(+)-based buffer the normal localization of actin was similarly defective in both htt(-) and nhe1(-) cells in a K(+)-based buffer, and the normal localization of Nhe1 was disrupted in the htt(-) mutant. These observations demonstrate that Htt and Nhel play roles in the same specific cation-facilitated behaviors and that Nhel localization is directly or indirectly regulated by Htt. Similar cation-dependent behaviors and a similar relationship between Htt and Nhe1 have not been reported for mammalian neurons and deserves investigation, especially as it may relate to Huntington׳s disease. PMID:25149514

  20. Mechanism of Electrochemical Catalytic Treatment of Phenol Wastewater Catalyzed by Metal Ion Supported on Cation Exchange Resin%苯酚水在离子交换树脂电化学降解中的机理研究

    Institute of Scientific and Technical Information of China (English)

    王莹; 侯党社; 韩莉萍

    2011-01-01

    The electrochemical oxidation of phenol in synthetic wastewater catalyzed by metal ion supported on cation exchange resin has been investigated.It was found that in the process of the phenol oxidation, hydroxyl radicals and Fe were all attribute to the phenol oxidation.%本文以负载金属的离子交换树脂为催化剂,采用电化学降解的方法研究了苯酚水的降解机理.研究表明苯酚水在离子交换树脂电化学降解中可能是由羟基自由基、金属氧化物、金属离子、电絮凝等协同作用下进行降解.

  1. Optimal dynamic capacity allocation of HVDC interconnections for cross-border exchange of balancing services in presence of uncertainty

    DEFF Research Database (Denmark)

    Delikaraoglou, Stefanos; Pinson, Pierre; Eriksson, Robert;

    2015-01-01

    The deployment of large shares of stochastic renewable energy, e.g., wind power, may bring important economic and environmental benefits to the power system. Nonetheless, their efficient integration depends on the ability of the power system to cope with their inherent variability and the...... balancing markets. Against this benchmark we compare two deterministic market designs with varying degrees of coordination between the reserve capacity and energy services, both followed by a real-time mechanism. Our study reveals the inefficiency of deterministic approaches as the shares of wind power...

  2. Ligand-exchange chromatographic separation of polycyclic aromatic hydrocarbons and polycyclic aromatic sulfur heterocycles on a chelating silica gel loaded with palladium (II) or silver (I) cations

    Energy Technology Data Exchange (ETDEWEB)

    Pyell, U.; Schober, S.; Stork, G. [Fachbereich Chemie der Philipps-Universitaet Marburg (Germany)

    1997-12-01

    2-Amino-1-cyclopentene-1-dithiocarboxylic acid silica gel (ACDA-SG) loaded with Ag(I) or Pd(II) ions has been examined for the group fractionation of polycyclic aromatic sulfur heterocycles (PASH) from polycyclic aromatic hydrocarbons (PAH) via ligand-exchange chromatography in the normal phase mode. It is shown that metal loading has a great impact on the selectivity of ACDA-SG for PASH and PAH. Pd(II) loaded ACDA-SG proved to be suitable for the group isolation of PASH from the aromatic fractions of petroleum mixtures (number of condensed rings{<=}3). (orig.) With 3 figs., 2 tabs., 14 refs.

  3. The ion-exchange capacity and Cs, Sr leachability of natural clinoptilolites at 200--300 C and PH{sub 2}O{sub sat}

    Energy Technology Data Exchange (ETDEWEB)

    Redkin, A.F. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of the Geology of Ore Deposits; Hemley, J.J.; Doughten, M.W.; Cygan, G.L. [Geological Survey, Reston, VA (United States)

    1995-12-31

    Clinoptilolites of three US clinoptilolite-rich tuff deposits, with different alkali and alkaline earth element mole ratios, were used for experimental investigation. The runs on stability and sorption ability were carried out in water and 0.3 molal chloride solution, using individual minerals and using assemblages containing microcline and analcime at 200 to 300 C and PH{sub 2}O{sub sat} water (duration of one month and two weeks). The clinoptilolites showed different behavior, unrelated to exchange capacity, when run under similar conditions. It was also found that Cs-bearing clinoptilolites contained 12--14 wt.% Cs after runs in 0.1mNaCl+0.1mKCl+ 0.1mCsCl, whereas Sr-bearing clinoptilolite contained about 3--5% Sr in 0.1mNaCl+0.1mKCl+0.05mSrCl{sub 2}. The compositional trend showed some linear variation between Sr and Cs content and Si/Al mole ratio up to Si/Al=5.0. Thermal investigation showed that (Na-K)rich clinoptilolite completely decomposes at 325 C, (Na-Mg) rich at 350 C and (Ca-Mg) rich at 375 C in runs of 2 weeks duration in pure water. Na-analcimes associated with clinoptilolites have low Cs and Sr adsorption capacity relative to the clinoptilolites. Na-Sr -bearing analcimes have an inverse dependence of Sr/(Sr+Na+K) mole ratio with Si/Al in the reaction of heterovalent exchange in analcime, where Na and Si replace Sr and Al. Thermodynamic calculation was done for the solubility of Cs and Sr-bearing clinoptilolites at 300 C, PH{sub 2}O{sub sat}. It was established that under some conditions Sr leachability from Sr-bearing clinoptilolite is insignificant whereas Cs-bearing clinoptilolite leachability is considerably higher.

  4. Extremely slow cation exchange processes in Li4SiO4 probed directly by two-time 7Li stimulated-echo nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Lithium self-diffusion in the low-temperature modification of polycrystalline lithium ortho-silicate Li4SiO4 is investigated by 7Li two-time stimulated echo NMR spectroscopy. Extremely slow Li exchange processes were directly monitored between 300 and 433 K by recording spin-alignment echoes as a function of mixing time varying over six decades from 10-5 to 10 s. In the investigated temperature range the hopping correlation functions show biexponential behaviour. Whereas the first decay step reflects directly Li jumps between electrically different sites, the second one is simply induced by the decay of alignment order due to quadrupolar relaxation. The echo decay rates τ-1 (101 s-1≤τ-1≤104 s-1), which can be identified with Li jump rates, show Arrhenius behaviour with an activation energy of 0.53(1) eV. The directly measured jump rates are in good agreement with those obtained recently by one- and two-dimensional 6Li exchange MAS NMR reported in the literature

  5. Studies on the characteristics of ion exchange resins in the purification system of nuclear power plants

    International Nuclear Information System (INIS)

    This research was conducted which involved the synthesis of ion exchange resin used for the purification of various water streams in nuclear power plants. Polymerization of styrene-divinyl-benzene solvent mixtures including catalyst yielded 40-100 mesh various types of beads. The copolymer beads were sulfonated with sulfuric acid to make cation exchange resin, were chloro-methylated with chloromethylmethylether and aminated with various amines in order to make anion exchange resin. The physical properties of copolymer beads and ion exchange resins were evaluated in this study. The cation exchange resin which was synthesized by using 8.5% divinylbenzene and diluent such as n-heptane had almost the same 4.6 meq/g, dry ion exchange capacity as 4.7 meq/g, dry of Westing House Specification WCAP-7452. But at higher divinylbenzene contents than 15%, the ion exchange capacity started to decrease. Anion exchange capacity in this experiment was lower than 3.5 meq/g,dry of Westing House Specification WCAP-7452. An anion exchange resin was synthesized from allylamine monomers via radiation induced-polymerization, and a new chelate resin was prepared from this resin by introducing a dithiocarbamate group, and the adsorption characteristics of metal ions was examined toward the chelate resin. (Author)

  6. Anion exchange membrane

    Science.gov (United States)

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

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  7. 航空煤油在不同价态金属离子交换介孔材料上的深度吸附脱硫%Deep desulfurization of jet fuel by adsorption over mesoporous materials exchanged with different metal cations

    Institute of Scientific and Technical Information of China (English)

    邱国欢; 孟祥瑞; 王玉和

    2013-01-01

    Three adsorbents were prepared by exchanging Ag+, Ni2+ and Ce3+ onto the aluminized large-pore-size SBA-15 (SBA-15-L). Desulfurization of model jet fuel containing 0.015(wt)% S were carried out using fixed-bed reactor. The results showed that the jet fuel can be desulfurized to 0.000l(wt)%. The sulfur capacity of Ag/Al-SBA-15-L was stronger than that of Ni/Al-SBA-15-L and Ce/Al-SBA-15-L L ICP-AES results exhibited that the loadings of Ag+ on the sorbent were 13 and 65 times as large as that of Ni2+ and Ce3+. The experiments of desulfurization illustrated that the ratios of adsorbed sulfur per Ag+, Ni2+ and Ce3+ cation were 0.027, 0.570 and 0.752 at adsorption saturation. And then, it was showed that the inherent sulfur capacity of these metal cations followed the order: Ce3+ > Ni2+> Ag+.%采用离子交换法,将不同价态的金属离子Ag+,Ni2+,Ce3+交换到铝化的大孔径SBA-15介孔材料(SBA-15-L)上,制备了吸附剂Ag/Al-SBA-15-L,Ni/Al-SBA-15-L,Ce/Al-SBA-15-L.脱硫实验表明,所制备的吸附剂可将硫含量为0.015(wt)%的模拟航空煤油,脱硫至硫含量低于0.0001 (wt)%,并且Ag/Al-SBA-15-L的吸附脱硫能力强于Ni/Al-SBA-15-L和Ce/Al-SBA-15.通过ICP-AES分析表明,在铝化的大孔SBA-15上,Ag+的交换量分别是Ni2+和Ce3+的13和65倍.达到吸附饱和时,每个活性中心离子Ag+、Ni2+、Ce3+上可分别吸附0.027,0.570,0.752个硫原子,即金属离子固有的吸附脱硫能力为Ce3+> Ni2+> Ag+.

  8. Effect of Clay Mineralogy and Exchangeable Cations on Permeability of Saudi Sandstone Reservoirs Effet de la minéralogie des argiles et des cations échangeables sur la perméabilité des réservoirs gréseux d'Arabie Saoudite

    Directory of Open Access Journals (Sweden)

    Dahab A. S.

    2006-11-01

    Full Text Available Reservoir rocks are susceptible to formation damage during secondary recovery operations due to the particular mineralogical, textural and electrochemical properties of the clay minerals they contain. This damage can be explained by the swelling of indigeneous clays present, resulting in the constricting of pores, or by the dispersion of indigeneous nonswelling particle rearrangements during fluid flow, resulting in the plugging of the pore system, or by a combination of the two. This article describes a laboratory study showing the effect of clay mineralogy on the permeability of actual Saudi sandstone reservoirs during water flooding operations. The study shows that the permeability damage of Saudi sandstone reservoirs depends upon the amount of swelling clays and exchangeable ions as well as on the nature of these ions. Monovalent cations cause more damage than multivalent ones but within the same group of metals, those with smaller atomic mass cause more damage. Les roches réservoirs peuvent être endommagées pendant les opérations de récupération secondaire à cause des propriétés minéralogiques, texturales et électrochimiques particulières des minéraux argileux qu'elles contiennent. Cet endommagement peut s'expliquer, soit par le gonflement des argiles qui conduit à un rétrécissement des pores, soit par la migration de particules non gonflantes pendant l'écoulement des fluides qui entraîne le colmatage des milieux poreux, soit par une combinaison des deux mécanismes. Cet article présente une étude de laboratoire montrant l'effet de la minéralogie des argiles sur la perméabilité des roches réservoirs réelles d'Arabie Saoudite pendant des opérations d'injection d'eau. L'étude montre que l'endommagement de la perméabilité des roches réservoirs d'Arabie Saoudite dépend de la quantité d'argiles gonflantes et d'ions échangeables, ainsi que de la nature de ces ions. Les cations monovalents provoquent plus d

  9. Bulk derivatization and cation exchange restricted access media-based trap-and-elute liquid chromatography–mass spectrometry method for determination of trace estrogens in serum

    International Nuclear Information System (INIS)

    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−1, and demonstrated good linearity of R2 from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL−1. Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified

  10. Determination of the exchange capacity of soils using radio-strontium; Determination de la capacite d'echange des sols au moyen du radio-strontium

    Energy Technology Data Exchange (ETDEWEB)

    Grauby, A.; Saas, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    In order to improve the technique and in particular to reduce the time required for measuring the exchange capacity of soils, the authors have developed a rapid measurement method based on the use of radio-active tracers. The element chosen for showing the occurrence of exchangeable bases is radio-strontium; it can displace the ions Ca{sup ++}, Mg{sup ++}, Na{sup ++}, K{sup +} from the soil. The use of a de-sorbent, barium chloride, makes it possible to recover the strontium fixed. A comparison of the results obtained using the two methods appears to be very satisfactory. The conventional method requires from 1 1/2 to 2 days - the radio-strontium method requires only 3 hours with the possibility also of carrying out large series of measurements. (authors) [French] Pour ameliorer la technique et surtout reduire le temps de manipulation que necessite la mesure de la capacite d'echange des sols, les auteurs ont mis au point une methode de mesure rapide qui fait appel aux traceurs radioactifs. C'est le radio-strontium qui a ete choisi pour la mise en evidence des bases echangeables. Il permet de deplacer les ions Ca{sup ++}, Mg{sup ++}, Na{sup ++}, K{sup +} du sol. Un desorbant, le chlorure de baryum, permet de recuperer la quantite du strontium fixe. La comparaison des resultats obtenus par les deux methodes semble tres satisfaisante. La methode classique necessite 1 jour et demi a 2 jours - la methode radiostrontium exige seulement 3 heures avec la possibilite de grandes series. (auteurs)

  11. Bulk derivatization and cation exchange restricted access media-based trap-and-elute liquid chromatography–mass spectrometry method for determination of trace estrogens in serum

    Energy Technology Data Exchange (ETDEWEB)

    Beinhauer, Jana [Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Bian, Liangqiao [Shimadzu Center for Advanced Analytical Chemistry, The University of Texas at Arlington, Arlington, TX (United States); Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); Fan, Hui [Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX (United States); Šebela, Marek [Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Kukula, Maciej [Shimadzu Center for Advanced Analytical Chemistry, The University of Texas at Arlington, Arlington, TX (United States); Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); Barrera, Jose A. [Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); and others

    2015-02-09

    Highlights: • Analysis of estrogens in small volume samples at low parts-per-trillion concentration. • Charged bulk derivatization facilitates on-line ion exchange sample preparation. • On-line WCX restricted access media traps analytes, but not proteins and lipids. • Complete preparation and LC–MS/MS analysis completed in 30 min/sample. - Abstract: Estrone (E1), estradiols (α/β-E2), and estriol (E3) are four major metabolically active estrogens exerting strong biological activities at very low circulating concentrations. This paper reports a sensitive and efficient method with automated, on-line clean-up and detection to determine trace estrogens in a small volume of serum samples using liquid chromatography–electrospray ionization–tandem mass spectrometry directly, without off-line liquid–liquid or solid-phase extraction pretreatments. Serum aliquots (charcoal stripped fetal bovine serum, 100 μL) were spiked with four estrogen standards and their corresponding isotope-labeled internal standards, then bulk derivatized with 2-fluoro-1-methyl-pyridium p-toluenesulfonate (2-FMP) to establish the calibration curves and perform method validation. Calibration was established in the concentration ranges of 5–1000 pg mL{sup −1}, and demonstrated good linearity of R{sup 2} from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL{sup −1}. Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified.

  12. Simultaneous determination of sub μg·g-1 levels of nine impurities in high purity iron by horizontal cation exchange resin mini-column and ICP-atomic emission spectrometry

    International Nuclear Information System (INIS)

    Inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been applied to the simultaneous determination of trace impurities in high purity iron after simultaneous separation. Sub μg·g-1 levels of Ca, Cd, Co, Cu, Mg, Mn, Ni, Pb and Zn in high purity iron which had been dissolved in hydrofluoric acid and hydrogen peroxide were separated from the iron matrix using a horizontal cation exchange resin mini-column. Flow rates and flow directions of solutions through the mini-column were controlled by a peristaltic pump. Adsorbed elements on the resin mini-column were rapidly eluted using a reverse flow of the eluant against the flow for the adsorption. The eluted elements were determined by ICP-AES using an internal standard method and good results were obtained. A 100-fold enrichment of analytes was obtained with this preconcentration system using 1 g of the sample in comparison with an ordinary sample solution in which 0.5 g of the sample was dissolved in 100 cm3 without separation. (author)

  13. Nearly 1000 Protein Identifications from 50 ng of Xenopus laevis Zygote Homogenate Using Online Sample Preparation on a Strong Cation Exchange Monolith Based Microreactor Coupled with Capillary Zone Electrophoresis.

    Science.gov (United States)

    Zhang, Zhenbin; Sun, Liangliang; Zhu, Guijie; Cox, Olivia F; Huber, Paul W; Dovichi, Norman J

    2016-01-01

    A sulfonate-silica hybrid strong cation exchange monolith microreactor was synthesized and coupled to a linear polyacrylamide coated capillary for online sample preparation and capillary zone electrophoresis-tandem mass spectrometry (CZE-MS/MS) bottom-up proteomic analysis. The protein sample was loaded onto the microreactor in an acidic buffer. After online reduction, alkylation, and digestion with trypsin, the digests were eluted with 200 mM ammonium bicarbonate at pH 8.2 for CZE-MS/MS analysis using 1 M acetic acid as the background electrolyte. This combination of basic elution and acidic background electrolytes results in both sample stacking and formation of a dynamic pH junction. 369 protein groups and 1274 peptides were identified from 50 ng of Xenopus laevis zygote homogenate, which is comparable with an offline sample preparation method, but the time required for sample preparation was decreased from over 24 h to less than 40 min. Dramatically improved performance was produced by coupling the reactor to a longer separation capillary (∼100 cm) and a Q Exactive HF mass spectrometer. 975 protein groups and 3749 peptides were identified from 50 ng of Xenopus protein using the online sample preparation method. PMID:26670623

  14. Development and validation of a UHPLC-MS/MS assay for colistin methanesulphonate (CMS) and colistin in human plasma and urine using weak-cation exchange solid-phase extraction.

    Science.gov (United States)

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

    2016-05-30

    A rapid ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) assay method was developed for determination of CMS and formed colistin in human plasma and urine. After extraction on a 96-well SPE Supra-Clean Weak Cation Exchange (WCX) plate, the eluents were mixed and injected into the UHPLC-MS/MS system directly. A Phonomenex Kinetex XB-C18 analytical column was employed with a mobile phase consisting of solution "A" (acetonitrile:methanol, 1:1, v/v) and solution "B" (0.1% formic acid in water, v/v). The flow rate was 0.4mL/min with gradient elution over 3.5min. 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 0.0251mg/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. PMID:26970986

  15. Changes in the Vibrational Spectra of Zeolites Due to Sorption of Heavy Metal Cations

    Science.gov (United States)

    Król, M.; Mozgawa, W.; Barczyk, K.; Bajda, T.; Kozanecki, M.

    2013-11-01

    This work presents the results of spectroscopic (MIR and Raman) studies of zeolite structures after immobilization of heavy metal cations from aqueous solutions. The sorption of Ag+, Cu2+, Cd2+, Pb2+, Zn2+, and Cr3+ ions has been conducted on zeolites belonging to different structural groups, i.e., sodium forms of natural chabazite, mordenite, ferrierite, and clinoptilolite, as well as on synthetic zeolite Y. Systematic changes in intensities and positions of the bands corresponding to the characteristic ring vibrations have been observed in the measured spectra. The most visible changes are observed in the FT-IR spectra of the samples in the range of 850-450 cm-1, and in the Raman spectra in the range of 600-250 cm-1. Depending on the zeolite structure, the bands, which can be regarded as a kind of indicator of ion exchange, were indentifi ed. For example, in the case of IR spectra, these bands are at 766, 703, 648, 578, and 506 cm-1 for zeolite Y, at 733 and 560 cm-1 for mordenite, at 675 cm-1 for clinoptilolite, etc. The degree of changes depends on both the type of cation and its concentration in the initial solution. This is connected with the way of binding of metal ions to the zeolite aluminosilicate framework, i.e., a proportion of the ion exchange and chemisorption in the process. Cations mainly undergoing ion exchange, such as Cd2+ or Pb2+, have the greatest impact on the character of the spectra. On the other hand, Cr3+ ions practically do not modify the spectra of zeolites. Results of IR and Raman spectroscopic studies have been compared with those obtained by atomic absorption spectroscopy (AAS), from which the proportion of ion exchange to chemisorption in the process and the effective cation exchange capacity of the individual samples have been estimated.

  16. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation

    Science.gov (United States)

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-01

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  17. Construction of porous cationic frameworks by crosslinking polyhedral oligomeric silsesquioxane units with N-heterocyclic linkers

    Science.gov (United States)

    Chen, Guojian; Zhou, Yu; Wang, Xiaochen; Li, Jing; Xue, Shuang; Liu, Yangqing; Wang, Qian; Wang, Jun

    2015-06-01

    In fields of materials science and chemistry, ionic-type porous materials attract increasing attention due to significant ion-exchanging capacity for accessing diversified applications. Facing the fact that porous cationic materials with robust and stable frameworks are very rare, novel tactics that can create new type members are highly desired. Here we report the first family of polyhedral oligomeric silsesquioxane (POSS) based porous cationic frameworks (PCIF-n) with enriched poly(ionic liquid)-like cationic structures, tunable mesoporosities, high surface areas (up to 1,025 m2 g-1) and large pore volumes (up to 0.90 cm3 g-1). Our strategy is designing the new rigid POSS unit of octakis(chloromethyl)silsesquioxane and reacting it with the rigid N-heterocyclic cross-linkers (typically 4,4‧-bipyridine) for preparing the desired porous cationic frameworks. The PCIF-n materials possess large surface area, hydrophobic and special anion-exchanging property, and thus are used as the supports for loading guest species PMo10V2O405- the resultant hybrid behaves as an efficient heterogeneous catalyst for aerobic oxidation of benzene and H2O2-mediated oxidation of cyclohexane.

  18. Radiation effects on a zeolite ion exchanger and a pollucite

    International Nuclear Information System (INIS)

    Cation exchange capacity and selective Cs and Sr ion sorption measurements were found to be too insensitive to detect radiation effects on irradiated Ionsiv-IE-95 zeolite. However, leaching the zeolite while under γ-irradiation caused a modest increase in the desorption of exchangeable ions. Gamma-irradiation and subsequent leaching of a natural pollucite also slightly enhanced the leachability of this material. The increased desorption of ions from the zeolite and the enhanced leachability of the pollucite are apparently caused by a decrease in pH due to the generation of acidic species during irradiation

  19. Cationic ruthenium alkylidene catalysts bearing phosphine ligands

    OpenAIRE

    Endo, Koji; Grubbs, Robert H.

    2016-01-01

    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bear-ing bulky phosphine ligands. Simple ligand exchange using silver(I) salts of non-coordinating or weakly coordinating anions pro-vided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported...

  20. Estimated times to exhaustion and power outputs at the gas exchange threshold, physical working capacity at the rating of perceived exertion threshold, and respiratory compensation point.

    Science.gov (United States)

    Bergstrom, Haley C; Housh, Terry J; Zuniga, Jorge M; Camic, Clayton L; Traylor, Daniel A; Schmidt, Richard J; Johnson, Glen O

    2012-10-01

    The purposes of this study were to compare the power outputs and estimated times to exhaustion (T(lim)) at the gas exchange threshold (GET), physical working capacity at the rating of perceived exertion threshold (PWC(RPE)), and respiratory compensation point (RCP). Three male and 5 female subjects (mean ± SD: age, 22.4 ± 2.8 years) performed an incremental test to exhaustion on an electronically braked cycle ergometer to determine peak oxygen consumption rate, GET, and RCP. The PWC(RPE) was determined from ratings of perceived exertion data recorded during 3 continuous workbouts to exhaustion. The estimated T(lim) values for each subject at GET, PWC(RPE), and RCP were determined from power curve analyses (T(lim) = ax(b)). The results indicated that the PWC(RPE) (176 ± 55 W) was not significantly different from RCP (181 ± 54 W); however, GET (155 ± 42 W) was significantly less than PWC(RPE) and RCP. The estimated T(lim) for the GET (26.1 ± 9.8 min) was significantly greater than PWC(RPE) (14.6 ± 5.6 min) and RCP (11.2 ± 3.1 min). The PWC(RPE) occurred at a mean power output that was 13.5% greater than the GET and, therefore, it is likely that the perception of effort is not driven by the same mechanism that underlies the GET (i.e., lactate buffering). Furthermore, the PWC(RPE) and RCP were not significantly different and, therefore, these thresholds may be associated with the same mechanisms of fatigue, such as increased levels of interstitial and (or) arterial [K⁺]. PMID:22716291

  1. Preparation and characterization of spermine-exchanged montmorillonite and interaction with the herbicide fluometuron

    OpenAIRE

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

    2012-01-01

    We studied the interaction between the naturally occurring polycation spermine (SPERM) and Na-exchanged SWy-2 Wyoming montmorillonite (Na-SWy-2 Mt) and between spermine-exchanged montmorillonite (Mt-SPERM) and the herbicide fluometuron. Mt-SPERM with spermine contents ranging between 0 and 1.2 times the cation exchange capacity (CEC) of Na-SWy-2 were studied by XRD, FTIR and TGA analysis. Spermine was intercalated stoichiometrically into Na-SWy-2 up to the CEC of the clay mineral, resulting i...

  2. Investigation of using Zeolite A and P synthesized from Iranian natural clinoptilolite for removal of heavy cations from simulated wastes

    International Nuclear Information System (INIS)

    Various methods have been used for the the removal o f heavy metal cations from mineral and industrial wastes. This research deals with the use of synthetic zeolites A and P synthesized from natural clinoptilolite for the removal process because of their superiority to ones. Ion exchange capacity of natural and synthetic samples was determined, then, the effects of some parameters such as temperature, time, and acidity on sorption were investigated as well as continues sorption. The sorption of lead cations was much better than that of other cations with the use of the synthetic samples and the rise in temperature and in pH has no significant effect. Sorption of this cations on the column was good. The results of cadmium sorption was promising and increasing the temperature increased the sorption and decreasing the pH decreased it. The sorption of zinc was rationally good; however it was less than previous cations, and increased with increasing the temperature. The results of nickel sorption in comparison with other cation, at high concentration was not promising. However, the results, at low concentration were good. Temperature had strong effect on nickel sorption

  3. Desalination by electrodialysis with ion-exchange membrane prepared by radiation-induced graft polymerization

    International Nuclear Information System (INIS)

    Ion-exchange membranes modified with triethylamine [-N(CH2CH3)3] and phosphoric acid (-PO3H) groups were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto polyolefin nonwavon fabric (PNF) and subsequent chemical modification of poly (GMA) graft chains. The physical and chemical properties of the GMA-grafted PNF and the PNF modified with ion-exchange groups were investigated by SEM and XPS. The ion-exchange capacities of the cation- and anion-exchange membrane were 0.20 and 1.24mmol/g, respectively. The content of cation- and anion exchange group increased with increasing grafting yield (d.g.=100%). Electrical resistance of PNF modified with TEA and -PO3H group decreased with increasing ion-exchange group capacities. Application of the graft-type ion-exchange membranes as separators for electrodialysis enabled use to reduce the time required to achieve 85.5% desalination of the 0.5M NaCl solution. (author)

  4. Experimental and density functional theory study of the adsorption of N2O onion-exchanged ZSM-5: Part II.The adsorption of N2O on main-group ion-exchanged ZSM-5

    Institute of Scientific and Technical Information of China (English)

    Bo Zhang; Yongan Lu; Hong He; Jianguo Wang; Changbin Zhang; Yunbo Yu; Li Xue

    2011-01-01

    The adsorption and desorption of N2O on main-group ion-exchanged ZSM-5 was studied using temperature-programmed desorption (TPD) and density functional theory (DFT) calculations.TPD experiments were carried out to determine the desorbed temperature Tmax corresponding to the maximum mass intensity of N2O desorption peak and adsorption capacity of N2O on metal-ion-exchanged ZSM5s.The results indicated that Tmax followed a sequence of Ba2+ > Ca2+ > Cs+ > K+ > Na+ > Mg2+and the amount of adsorbed N2O on main-group metal cation followed a sequence of Ba2+ > Mg2+ > Ca2+ > Na+ > K+ > Cs+.The DFT calculations were performed to obtain the adsorption energy (Eads), which represents the strength of the interaction between metal cations and the N-end or O-end of N2O.The calculation results showed that the N-end of the N2O molecule was favorably adsorbed on ion-exchanged ZSM-5, except for Cs-ZSM-5.For alkali metal cations, the Eads of N2O on cations followed the order which was the same to that of Tmax: Cs+ > K+ > Na+.The calculated and experimental results consistently showed that the adsorption performances of alkaline-earth metal cations were better than those of alkali metal cations.

  5. Europium exchange behaviour of synthetic smectites: spectroscopic and microcalorimetric studies of the influence of structural properties

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Full text of publication follows: Among the various soils compounds, clays contribute largely to the transport of heavy metal cations, because of their high cation exchange capacity. The interaction of cations with clay sheets is strongly dependent on the structure of the latter and on the location of their charge deficit, thereby following the type of clays. The intention of the present work was to study the influence of structural properties of synthetic clays on their ion adsorption properties, and the interactions of the exchangeable cations in the interlayer space with water and with clay sheets. Homo-ionic Na-beidellites and Na-montmorillonite with various structural charges were synthesized and finely characterized. Adsorption capacity measurements of Eu(III) were determined. Special attention was paid to the control of the speciation diagram of Eu(III), the hydrolysis, and thus the control of the pH in aqueous suspension. The concentration of Eu(III) was determined with the aid of ionic chromatography analyzer, using UV detection, after optimizing the composition of the mobile phase and the post-column reagent. Time- Resolved Laser Spectroscopy was used to determine the hydration state of the free and the adsorbed species. Isotherm Titration Calorimetry measurements were carried out to determine the heat effect due to the exchange mechanisms. This work has been partially funded by the ANR (CILSAMES project (ANR-07-JCJC-0044) and the GNR Paris 1115. (authors)

  6. Hidrólise parcial da superfície do polyethylene terephthalate (PET: transformando um rejeito em um material de troca catiônica para aplicação ambiental Partial hydrolysis of pet surface: transforming a plastic waste into a material with cationic exchange properties for environmental application

    Directory of Open Access Journals (Sweden)

    Marcelo G. Rosmaninho

    2009-01-01

    Full Text Available In this work it is proposed a simple and versatile undergraduate chemical experiment in polymer and environmental technology based on the process of polyethylene terephthalate (PET hydrolysis. Polyethylene terephthalate from post-consume bottles is submitted to a controlled partial hydrolysis which allows the students to follow the reaction by a simple procedure. The students can explore the reaction kinetics, the effect of catalysts and the exposed polyethylene terephthalate surface area on the hydrolysis reaction. The second and innovative part of this experiment is the technological and environmental application of the hydrolyzed polyethylene terephthalate as a material with cation exchange properties. The surface hydrolyzed polyethylene terephthalate can be used as adsorbent for cationic contaminants.

  7. Cation locations and dislocations in zeolites

    Science.gov (United States)

    Smith, Luis James

    The focus of this dissertation is the extra-framework cation sites in a particular structural family of zeolites, chabazite. Cation sites play a particularly important role in the application of these sieves for ion exchange, gas separation, catalysis, and, when the cation is a proton, acid catalysis. Structural characterization is commonly performed through the use of powder diffraction and Rietveld analysis of powder diffraction data. Use of high-resolution nuclear magnetic resonance, in the study of the local order of the various constituent nuclei of zeolites, complements well the long-range order information produced by diffraction. Recent developments in solid state NMR techniques allow for increased study of disorder in zeolites particularly when such phenomena test the detection limits of diffraction. These two powerful characterization techniques, powder diffraction and NMR, offer many insights into the complex interaction of cations with the zeolite framework. The acids site locations in SSZ-13, a high silica chabazite, and SAPO-34, a silicoaluminophosphate with the chabazite structure, were determined. The structure of SAPO-34 upon selective hydration was also determined. The insensitivity of X-rays to hydrogen was avoided through deuteration of the acid zeolites and neutron powder diffraction methods. Protons at inequivalent positions were found to have different acid strengths in both SSZ-13 and SAPO-34. Other light elements are incorporated into zeolites in the form of extra-framework cations, among these are lithium, sodium, and calcium. Not amenable by X-ray powder diffraction methods, the positions of such light cations in fully ion-exchanged versions of synthetic chabazite were determined through neutron powder diffraction methods. The study of more complex binary cation systems were conducted. Powder diffraction and solid state NMR methods (MAS, MQMAS) were used to examine cation site preferences and dislocations in these mixed-akali chabazites

  8. The heats of adsorption of metal cations on silica gel with covalently fixed polyaspartic acid

    International Nuclear Information System (INIS)

    Temperature dependence of retaining cations of alkali (Li-Cs), alkaline-earth (Mg, Ca, Sr, Ba) metals and cadmium on silica gel with covalently fixed polyaspartic acid, as well as on carboxylic cation exchangers Universal Cation and Selekton K, was studied by the method of chromatography in the temperature range of 27-62 deg C. On the basis of the experimental data obtained adsorption heat of alkali and alkaline-earth metal cations was calculated. It was ascertained that for all the sorbents studied ion exchange prevails in retaining mechanism. Three types of cation retaining dependence on chromatographic column temperature were considered

  9. Declines in Soil pH due to Anthropogenic Nitrogen Inputs Alter Buffering and Exchange Reactions in Tropical Forest Soils

    Science.gov (United States)

    Lohse, K. A.

    2003-12-01

    Anthropogenic nitrogen (N) inputs may alter tropical soil buffering and exchange reactions that have important implications for nutrient cycling, forest productivity, and downstream ecosystems. In contrast to relatively young temperate soils that are typically buffered from N inputs by base cation reactions, aluminum reactions may serve to buffer highly weathered tropical soils and result in immediate increases in aluminum mobility and toxicity. Increased nitrate losses due to chronic N inputs may also deplete residual base cations in already weathered base cation-poor soils, further acidify soils, and thereby reduce nitrate mobility through pH-dependent anion exchange reactions. To test these hypotheses, I determined soil pH and cation and anion exchange capacity (CEC and AEC) and measured base cation and aluminum soil solution losses following first-time and long-term experimental N additions from two Hawaiian tropical forest soils, a 300 year old Andisol and a 4.1 million year old Oxisol. I found that elevated base cation losses accompanied increased nitrate losses after first time N additions to the young Andisol whereas immediate and large aluminum losses were associated with increased nitrate losses from the Oxisol. In the long-term, base cation and aluminum losses increased in proportion to nitrate losses. Long-term N additions at both sites resulted in significant declines in soil pH, decreased CEC and increased AEC. These results suggest that even chronic N inputs resulting in small but elevated nitrate losses may deplete residual base cations, increase mobility and toxicity of aluminum, and potentially lead to declines in forest productivity and acidification of downstream ecosystems. These findings also suggest that AEC may provide a long-term mechanism to delay nitrate losses in tropical forests with significant variable charge that are experiencing chronic anthropogenic N inputs.

  10. 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

    OpenAIRE

    Cassio Hamilton Abreu Jr.; Takashi Muraoka; Fernando Carvalho Oliveira

    2001-01-01

    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...

  11. Synthesis and chemical modification of polymeric resins for the treatment of cations and aromatic hydrocarbons in produced oily water; Sintese de modificacao quimica de resina polimerica e aplicacao na remocao de cations e hidrocarbonetos aromaticos presentes em agua produzida

    Energy Technology Data Exchange (ETDEWEB)

    Aversa, Thiago M.; Rodrigues, Monique F.; Vieira, Helida V.P.; Queiros, Yure G.C.; Lucas, Elizabete F. [Universidade Federal do Rio de Janeiro, Instituto de Macromoleculas, Lab. de Macromoleculas e Coloides na Industria do Petroleo, Rio de Janeiro, RJ (Brazil)], e-mail: thiagoaversa@ima.ufrj.br

    2011-07-01

    The use of chemically modified resins in oily water treatment process is not very developed yet. Because of this, this work suggests to study the styrene and divinylbenzene sulfonation effect on oil and grease, aniline and calcium removal from the water. The aniline, oils and greases belong to a class of toxic organic compounds, with the Brazilian maximum limits established for disposal in CONAMA 393/2007, while the calcium ions belong to the group of cations of alkaline earth metals which improve hardness to the water, may cause fouling as carbonates and sulfates form. By using sulfonated resins in oily water treatment it is possible to remove not only oils and greases but also calcium and aniline. These kinds of polar compounds are removed because of the cation exchange capacity of resin. (author)

  12. Studies on the ion-exchange behaviour of chromium ferrocyanide

    International Nuclear Information System (INIS)

    The sorption of univalent, bivalent and trivalent ions has been studied on chromium ferrocyanide gel. The distribution of various metal cations were determined by shaking the exchanger (0.1 g) and 20 ml of 0.005M metal ion solution of pH 2-3, till equilibrium was attained. The concentration of Pb2+, Cu2+, Mn2+, Ni2+, Mg2+ and Al3+ were determined by EDTA, ZrO2+, Th4+, UO2+ and Fe2+ were estimated spectrophotometrically and radiometric methods were used for Rb+, Cs+, Tl+, Ag+, Zn2+, Co2+, Cd2+, Hg2+ and Fe3+ metal ions. The distribution coefficients of various univalent, bivalent and trivalent metal ions (0.002M) were also determined as a function of NH4NO3 and HNO3 concentrations and pH. The studies reveal a high sorption capacity for Cs+, Tl+, Ag+, Cu2+, Zn2+, Cd2+, Fe3+ and Th4+. The sorption of monovalent cations show purely ion exchange mechanism while the uptake of bivalent and trivalent cations is non-equivalent in nature. Single elution of Rb+, Cs+ and Tl+ has been performed from the columns of this exchanger and the recovery is almost complete in all the cases. Cu2+ and Ag+ get completely adsorbed on the gel column and their elution is not possible probably due to the formation of some new solid phases. Depending on the Ksub(d) values of the metal ions, a large number of separations of radiochemical as well as analytical importance can be performed on the columns of this exchanger material. It is apparent from the Ksub(d) values that a number of separations as Hg2+ from Mg2+, Ca2+ and Pb2+; Mg2+ from Mn2+: Fe3+ from Al3+; and Th4+ from ZrO2+ can be performed on the columns of this exchanger. (T.G.)

  13. Cation-cation interaction in neptunyl(V) compounds

    International Nuclear Information System (INIS)

    The original manuscript was prepared by Professor N.N. Krot of Institute of Physical Chemistry, Russian Academy of Sciences, in 1997. Saeki tried to translate that into Japanese and to add some new data since 1997. The contents include the whole picture of cation-cation interactions mainly in 5-valence neptunium compounds. Firstly, characteristic structures of neptunium are summarized of the cation-cation bonding in compounds. Secondly, it is mentioned how the cation-cation bonding affects physical and chemical properties of the compounds. Then, characterization-methods for the cation-cation bonding in the compounds are discussed. Finally, the cation-cation interactions in compounds of other actinide-ions are shortly reviewed. (author)

  14. Effects of humic acid-based buffer + cation on chemical characteristics of saline soils and maize growth

    Directory of Open Access Journals (Sweden)

    W. Mindari

    2014-10-01

    Full Text Available Humic acid is believed to maintain the stability of the soil reaction, adsorption / fixation / chelate of cation, thereby increasing the availability of water and plant nutrients. On the other hand, the dynamics of saline soil cation is strongly influenced by the change of seasons that disrupt water and plant nutrients uptake. This experiment was aimed to examine the characteristics of the humic acid from compost, coal, and peat and its function in the adsorption of K+ and NH4+ cations, thus increasing the availability of nutrients and of maize growth. Eighteen treatments consisted of three humic acid sources (compost, peat and coal, two cation additives (K+ and NH4+, and three doses of humic acid-based buffer (10, 20, and 30 g / 3kg, were arranged in a factorial completely randomized with three replicates. The treatments were evaluated against changes in pH, electric conductivity (EC, cation exchange capacity (CEC, chlorophyll content, plant dry weight and plant height. The results showed that the addition of K+ and NH4+ affected pH, CEC, K+, NH4+, and water content of the buffer. Application of humic acid-based buffer significantly decreased soil pH from > 7 to about 6.3, decreased soil EC to 0.9 mS / cm, and increased exchangeable Na from 0.40 to 0.56 me / 100g soil, Ca from 15.57 to 20.21 me/100 g soil, Mg from 1.76 to 6.52 me/100 g soil, and K from 0.05-0.51 me / 100g soil. Plant growth (plant height, chlorophyll content, leaf area, and stem weight at 35 days after planting increased with increasing dose of humic acid. The dose of 2.0g peat humic acid + NH4+ / 3 kg of soil or 30g peat humic acid + K+ / 3 kg of oil gave the best results of maize growth.

  15. Research on Purification Process of Vindoline and Catharanthine from Catharanthus roseus by Means of Cation Exchange Resin%阳离子交换树脂纯化长春花中文多灵和长春质碱的工艺优选

    Institute of Scientific and Technical Information of China (English)

    柏道鸣; 周广涛; 代龙

    2012-01-01

    Objective: To select the optimum purifying process of Vindoline and Catharanthine from Catharanthus roseus by means of cation exchange resin. Method: The purifying process of Vindoline and Catharanthine from Catharanthus roseus was performed by cation exchange resin of LSD-001 type, with the solvent of ammonia water, the mixture of ammonia water and ethanol, acid water, the mixture of acid water and ethanol, the mixture of sodium chloride and ethanol, and the content of two alkaloids were determined to choose the optimal technological parameters. Result: The ideal concentration of solvent was: with 80% ethanol ( containing 1% sodium chloride ) eluent elution, two alkaloids eluting attained the highest rate. Conclusion : The purification process has well effect.It can be used for purifying Vindoline and Catharanthine from Catharanthus roseus by means of cation exchange resin.%目的:考察阳离子交换树脂不同洗脱溶剂纯化长春花中文多灵和长春质碱的效果,优选最佳工艺条件.方法:采用LSD-001大孔型阳离子交换树脂对长春花中文多灵和长春质碱进行纯化,以两种生物碱含量为指标,考察以氨水、氨性乙醇、酸水、酸性乙醇、盐醇为洗脱剂纯化两种生物碱的效果.结果:经过优选,离子交换树脂的最佳洗脱条件为:以80%乙醇(含1%氯化钠)洗脱剂洗脱时,两种生物碱的洗脱率最高.结论:优选得到的工艺纯化长春花中文多灵和长春质碱效果好,节省溶剂,工艺简单,可用于长春花中两种生物碱的分离纯化.

  16. Catalytic performance of the exchanged Y faujasites by Ce3+, La3+, UO22+, Co2+, Sr2+, Pb2+, Tl+ and NH4+ cations in the disproportionation reaction of toluene

    International Nuclear Information System (INIS)

    The catalytic performance of exchanged Y faujasites by Ce3+, La3+, UO22+, Co2+, Sr2+, Pb2+, Tl+ and NH4+ ions were studied in a disproportionation reaction in the gaseous phase. It was shown that total acidity generated by exchanged ions is responsible of the catalytic activity. Rare earths (cerium, lanthanum and uranium) catalysts have appreciable performance and allowed one to obtain an important xylenes proportion at 400 to 450 C. The decrease of xylenes and trimethyl-benzenes proportion in studied catalysts shows the implication of xylenes in toluene disproportionation reaction. (authors)

  17. Determination of Zeolite Cation Exchange Capacity by Automatic Titrator%自动滴定仪用于沸石阳离子交换容量测定的方法

    Institute of Scientific and Technical Information of China (English)

    蒲思川; 冯启明

    2008-01-01

    以甲醛法为基础,采用自动滴定仪电位滴定法测定沸石的阳离子交换容量,与pH计指示法、酸碱指示剂法相比,仪器灵敏度高、操作简单,使测定结果具有更高的准确度和更好的重复性.

  18. Electromechanical performance and other characteristics of IPMCs fabricated with various commercially available ion exchange membranes

    International Nuclear Information System (INIS)

    Ionic polymer–metal composites (IPMCs) are considered as some of the favorable candidates to be used as biomimetic actuators and sensors in an aqueous environment. Amongst all components that compose an IPMC, the ion exchange membrane is where hydrated cations migrate when an electric field is applied across the membrane and it eventually produces the deformation of the IPMC. Nafion® is the most commonly used ion exchange membrane. Many studies have been conducted on IPMCs made with Nafion®. In this study, three other commercially available ion exchange membranes were used to fabricate IPMCs and their performance as actuators was compared with IPMCs made with Nafion® membrane. Their potential for use in IPMC actuators was investigated by conducting various characterizations such as water uptake, ion exchange capacity, morphology, thermal property, blocking force and bending displacement. (paper)

  19. Influence of the ionic liquid cation on the solvent extraction of trivalent rare-earth ions by mixtures of Cyanex 923 and ionic liquids.

    Science.gov (United States)

    Rout, Alok; Binnemans, Koen

    2015-01-21

    Trivalent rare-earth ions were extracted from nitric acid medium by the neutral phosphine oxide extractant Cyanex 923 into ionic liquid phases containing the bis(trifluoromethylsulfonyl)imide anion. Five different cations were considered: 1-butyl-3-methylimidazolium, 1-decyl-3-methylimidazolium, methyltributylammonium, methyltrioctylammonium and trihexyl(tetradecyl)phosphonium. The extraction behavior of neodymium(iii) was investigated as a function of various parameters: pH, extractant concentration, concentration of the neodymium(iii) ion in the aqueous feed and concentration of the salting-out agent. The loading capacity of the ionic liquid phase was studied. The extraction efficiency increased with increasing pH of the aqueous feed solution. The extraction occurred for all ionic liquids via an ion-exchange mechanism and the extraction efficiency could be related to the solubility of the ionic liquid cation in the aqueous phase: high distribution ratios for hydrophilic cations and low ones for hydrophobic cations. Addition of nitrate ions to the aqueous phase resulted in an increase in extraction efficiency for ionic liquids with hydrophobic cations due to extraction of neutral complexes. Neodymium(iii) could be stripped from the ionic liquid phase by 0.5-1.0 M nitric acid solutions and the extracting phase could be reused. The extractability of other rare earths present in the mixture was compared for the five ionic liquids. PMID:25423581

  20. Synthesis of new electroactive polymers by ion-exchange replacement of Mg(II) by 2H+ or Zn(II) cations inside Mg(II) polyporphine film, with their subsequent electrochemical transformation to condensed-structure materials

    International Nuclear Information System (INIS)

    It has been demonstrated that the treatment of the magnesium polyporphine of type I, pMgP-I, by trifluoroacetic acid in acetonitrile may be used to replace initial central Mg(II) cations inside the monomeric macrocycle units by protons, to get a new electroactive polymer, “free-base polyporphine of type I”, pH2P-I. In its turn, these inserted protons may be replaced by Zn(II) cations via the film treatment with zinc acetate in organic solvent, to get another new electroactive polymer, “zinc polyporphine of type I”, pZnP-I. These changes of central ions inside monomer units manifest themselves by characteristic modifications of their electroactive properties as well as of UV–visible and IR spectra. Similar to the magnesium polyporphine of type I, pMgP-I, studied in our previous paper (Electrochim. Acta, 2010, 55, 6703) both new polymers are subject to an irreversible electrooxidative transformation into the corresponding polyporphines of type II, pH2P-II and pZnP-II. All these polyporphines of type II demonstrate a very broad range of their redox activity, without any potential interval of non-electroactivity. It means that they represent electroactive polymers with a zero-width band gap in the neutral state of the polymer and the Fermi level is located into a broad electronic band for a wide range of the positive and negative oxidation states. Expected molecular structures of all these polymers are discussed

  1. Composition of exchangeable bases and acidity in soils of the Crimean Mountains

    Science.gov (United States)

    Kostenko, I. V.

    2015-08-01

    Acid forest and mountainous meadow soils of the Crimean Mountains were studied. The amount of hydrogen and aluminum ions extracted from these soils depended on the pH of extracting agents. The maximum values of the soil acidity were obtained upon the extraction with a strongly alkaline solution of sodium acetate in 0.05 N NaOH. The application of this extractant made it possible to determine the total exchange acidity, the total amount of extractable aluminum, and the total cation exchange capacity of the soils after the extraction of all the acidic components from them. The values of these characteristics were significantly higher than the values of the potential acidity and cation exchange capacity obtained by the routine analytical methods. Hydrogen predominated among the acidic components of the exchange acidity in the humus horizons, whereas aluminum predominated among them in the underlying mineral horizons. Hydrothermic conditions and the character of vegetation and parent materials were the major factors affecting the relationships between bases and acidic components in the soil adsorption complex.

  2. Carrying Capacity

    DEFF Research Database (Denmark)

    Schroll, Henning; Andersen, Jan; Kjærgård, Bente

    2012-01-01

    carrying capacity (SCC) and assimilative carrying capacity (ACC). The act mandates that the latter two aspects must be taken into consideration in the local spatial plans. The present study aimed at developing a background for a national guideline for carrying capacity in Indonesian provinces and districts...... carrying capacity (ACC). The act mandates that the latter two aspects must be taken into consideration in the local spatial plans. The present study aimed at developing a background for a national guideline for carrying capacity in Indonesian provinces and districts/cities. Four different sectors (water...

  3. New data on Cu-exchanged phillipsite: a multi-methodological study

    Science.gov (United States)

    Gatta, G. Diego; Cappelletti, Piergiulio; de'Gennaro, Bruno; Rotiroti, Nicola; Langella, Alessio

    2015-10-01

    The cation exchange capacity of a natural phillipsite-rich sample from the Neapolitan Yellow Tuff, Southern Italy (treated in order to obtain a 95 wt% zeolite-rich sample composed mainly of phillipsite and minor chabazite) for Cu was evaluated using the batch exchange method. The sample had previously been exchanged into its monocationic form (Na), and then used for the equilibrium studies of the exchange reaction 2Na+ ⇆ Cu2+. Reversibility ion exchange tests were performed. The isotherm displays an evident hysteresis loop. Interestingly, the final Cu-exchanged polycrystalline material was green-bluish. Natural, Na- and Cu-exchanged forms were analyzed by X-ray powder diffraction, and the Cu-phillipsite was also investigated by transmission electron microscopy (TEM). Structure refinement of Cu-phillipsite was performed by the Rietveld method using synchrotron data, and it indicates a small, but significant, fraction of Cu sharing with Na two-three independent extra-framework sites. The TEM experiment shows sub-spherical nano-clusters of crystalline species (with average size of 5 nm) lying on the surfaces of zeolite crystals or dispersed in the amorphous fraction, with electron diffraction patterns corresponding to those of CuO (tenorite-like structure) and Cu(OH)2 (spertiniite-like structure). X-ray and TEM investigations show that Cu is mainly concentrated in different species (crystalline or amorphous) within the sample, not only in phillipsite. The experimental findings based on X-ray and TEM investigations, along with the hysteresis loop of the ion exchange tests, are discussed and some general considerations about the mechanisms of exchange reactions involving divalent cations with high hydration energy are provided.

  4. Treatment of Spent ion-Exchange Resins from NPP by Supercritical Water Oxidation (SCWO) Process

    International Nuclear Information System (INIS)

    The spent cationic exchange resins and anionic exchange resins were separated from mixed spent exchange resins by a fluidized bed gravimetric separator. The separated resins were identified by an elemental analysis and thermogravimetric analysis. The each test sample was prepared by diluting the slurry made by wet ball milling the cationic exchange resins and the anionic exchange resins separated as a spherical granular form for 24 hours. The resulting test samples showed a slurry form of less than 75 μm of particle size and 25,000 ppm of CODcr. The decomposition conditions of each test samples from a thermal power plant were obtained with a lab-scale(reactor volume: 220 mL) supercritical water oxidation (SCWO) facility. Then pilot plant(reactor volume : 24 L) tests were performed with the test samples from a thermal power plant and a nuclear power plant successively. Based on the optimal decomposition conditions and the operation experiences by lab-scale facility and the pilot plant, a commercial plant(capacity: 150 kg/h) can be installed in a nuclear power plant was designed.

  5. Development of a Waste Water Regenerative System - Using Sphagnum Moss Ion-exchange

    Science.gov (United States)

    McKeon, M.; Wheeler, R.; Leahy, Jj

    The use of inexpensive, light weight and regenerative systems in an enclosed environment is of great importance to sustained existence in such habitats as the International Space Station, Moon or even Mars. Many systems exist which utilise various synthetic ion exchangers to complete the process of waste water clean-up. These systems do have a very good exchange rate for cations but a very low exchange rate for anions. They also have a maximum capacity before they need regeneration. This research proposes a natural alternative to these synthetic ion-exchangers that utilises one of natures greatest ion-exchangers, that of Sphagnum Moss. Sphagna can be predominantly found in the nutrient poor environment of Raised Bogs, a type of isolated wetland with characteristic low pH and little interaction with the surrounding water table. All nutrients come from precipitation. The sphagna have developed as the bog's sponges, soaking up all available nutrients (both cation & anion) from the precipitation and eventually distributing them to the surrounding flora and fauna, through the water. The goal of this research is to use this ability in the processing of waste water from systems similar to isolated microgravity environments, to produce clean water for reuse in these environments. The nutrients taken up by the sphagna will also be utilised as a growth medium for cultivar growth, such as those selected for hydroponics' systems.

  6. CHARACTERIZATION OF REACTIVE FORMATIONS: A VISION FOR THE CAPACITY EXPANSION

    Directory of Open Access Journals (Sweden)

    Danielly Vieira de Lucena

    2013-12-01

    Full Text Available All classes of clay minerals absorb water, but the smectite absorb much larger volumes than the other classes because of its expanded network. During the drilling of oil wells it is common for the detection of layers consisting of clay minerals high grade of hydration arranged in laminar packages. When in contact with water, the packets are separated clay as the water enters the basal spacing. This phenomenon is known as expansion or swelling. Given this, this paper aims to characterize shales in two regions of the country to explain the susceptibility of hydration of each of these formations. The characterization was done by making use of Exchange cation capacity (ECC, X-ray fluorescence (XRF, diferential thermal analysis (DTA, Thermogravimetry (TGA and X-ray diffraction (XRD. The results obtained showed that among the shales studied, those with the greatest degree of clay fractions (smectite in its composition showed higher swelling index according to the methodology of Foster.

  7. Preparation and characterization of ion exchange membrane by radiation-induced grafting for vanadium redox flow battery

    International Nuclear Information System (INIS)

    By using the radiation grafting method, fluoropolymer membranes were grafted with different functional monomers to synthesize cation exchange membrane (CEM), anion exchange membrane (AEM) and amphoteric ion exchange membrane (AIEM), respectively. The binary CEM was prepared by simultaneous grafting styrene (St) and maleic anhydride (MAn) into poly (tetrafluoroethylene) (PTFE) film, which showed high ion exchange capacity(IEC) and conductivity. The AEM was synthesized by grafting dimethylaminoethyl methacrylate (DMAEMA) into ETFE film, and found that the self-discharge of VRFB was suppressed effectively because of the Donnan repulsion effect. To combine the advantages of CEM and AEM, the AIEM was prepared by simultaneous grafting St and DMAEMA into ETFE film. The obtained AIEM exhibited high conductivity, and significantly reduced permeability of vanadium ions. The VRFB assembled with the AIEM maintained an open circuit voltage (OCV) higher than 1.3 V for 300 h, and no efficiency decline was observed after testing more than 40 cycles. (authors)

  8. Two different cationic positions in Cu-SSZ-13?

    Science.gov (United States)

    Hun Kwak, Ja; Zhu, Haiyang; Lee, Jong H; Peden, Charles H F; Szanyi, János

    2012-05-16

    H(2)-TPR and FTIR were used to characterize the nature of the Cu ions present in the Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ions at two distinct cationic positions in the SSZ-13 framework. PMID:22473309

  9. Two different cationic positions in Cu-SSZ-13?

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Zhu, Haiyang; Lee, Jong H.; Peden, Charles HF; Szanyi, Janos

    2012-04-18

    H2-TPR and FTIR were used to characterize the Cu ions present in Cu-SSZ-13 zeolite at different ion exchange levels. The results obtained are consistent with the presence of Cu ions in two distinct cationic positions of the SSZ-13 framework.

  10. The role of temperature in ion exchange processes of separation and purification of substances and water treatment

    International Nuclear Information System (INIS)

    The influence of temperature on the equilibrium, dynamic properties on ion exchange separation and purification processes is discussed. For all of the studied cation exchangers (sulphonic, carboxylic, phosphonic) the selectivity towards divalent ions of the alkali earth and transition metals increases with temperature. The temperature effects for the polyacrylic and polymethacrylic resins have been found to be the most strong. The K values for the chelating resins depend on temperature very slightly in case of exchange of the alkali earth and alkali metals ions and decrease visibly with temperature in case of exchange of transition and alkali metals ions and decrease visibly with temperature in case of exchange of transition and alkali metals ions. Due to the different effects of temperature, cation exchangers become for some solution compositions more selective than the chelating resins at high temperature. Temperature affect the capacity of resins as well. The effect of the temperature on the shape and length of a sorption front is rather complex due to the temperature dependencies of mass transfer or diffusion coefficients, selectivity coefficients and of resin swelling. The increase of both mass transfer coefficients and selectivity coefficients stimulated by the temperature leads to the sharpening of the sorption front. The evolution of the separation processes by use of the temperature effects are considered as well as some problems of theory and experimentation. 2 figs., 5 refs

  11. A single pump cycling-column-switching technique coupled with homemade high exchange capacity columns for the determination of iodate in iodized edible salt by ion chromatography with UV detection.

    Science.gov (United States)

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

    2013-08-15

    A single pump cycling-column-switching technique has been developed for the iodate analysis in edible salt. Homemade high exchange capacity columns were adopted for the separation of iodate and chloride. Iodate could be retained and concentrated in a homemade concentrator column after eluents passing through the suppressor. With UV detection, iodate exhibited satisfactory linearity in the range of 0.1-10.0 mg/L with a correlation coefficient of 0.9996. The detection limit (LOD) was 45.53 μg/L, based on the signal-to-noise ratio of 3 (S/N=3) and a 100 μL injection volume. Relative standard deviations (RSDs) for retention time, peak area and peak height were all less than 2.1%. Recoveries of added iodate were in the range of 98.4-101.6% for the spiked samples. The quantitative determination of iodate in edible salt was accomplished by this column-switching technique, without any pretreatment and interference. The results on six samples were statistically compared with results determined by conventional titrimetric method. PMID:23561090

  12. Competitive Effects of 2+ and 3+ Cations on DNA Compaction

    CERN Document Server

    Tongu, C; Yoshikawa, Y; Zinchenko, A A; Chen, N; Yoshikawa, K

    2016-01-01

    By using single-DNA observation with fluorescence microscopy, we observed the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA with 166 kbp). It was found that divalent cations, such as Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. These experimental observations are inconsistent with the well-established Debye-Huckel scheme regarding the shielding effect of counter ions, which is given as the additivity of contributions of cations with different valences. We interpreted the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counter ions before and after the folding transition of DNA. For the compaction with SPD(3+), we considered the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly-charged polyelectrolyte, double-st...

  13. Cationic Antimicrobial Peptide Cytotoxicity

    OpenAIRE

    Laverty, Garry; Gilmore, Brendan

    2014-01-01

    Fluorescence microscopy serves as a valuable tool for assessing the structural integrity and viability of eukaryotic cells. Through the use of calcein AM and the DNA stain 4,6-diamidino-2 phenylindole (DAPI), cell viability and membrane integrity can be qualified. Our group has previously shown the ultra-short cationic antimicrobial peptide H-OOWW-NH2; the amphibian derived 27-mer peptide Maximin-4and the ultra-short lipopeptide C12-OOWW-NH2 to be effective against a range of bacterial biofil...

  14. Study on cationic photopolymerization reaction of epoxy polysiloxane

    Science.gov (United States)

    Sun, F.; Jiang, S. L.; Liu, J.

    2007-11-01

    The effects of epoxy monomers, concentration of photoinitiator and radical photoinitiators on the photosensitive properties of cationic phopolymerization system with a novel epoxy polysiloxane oligomer (CEPS) were investigated via a gel yield method. The results showed that among the tested epoxy monomers, the reactivity of ERL-4221 with cycloaliphatic epoxy groups was the highest. The optimum concentration of diaryldiodonium salt (SR-1012) was determined as 4-5 wt.%. Increasing the amounts of ERL-4221 in the CEPS cationic photopolymerization system, UV-curing rate increased. Radical photoinitiators with ArC dbnd O structure possessed sensitization capacity to the cationic photoinitiator SR-1012. The photosensitivity of the CEPS system could be up to 165 mJ/cm 2. Adding a small amount of IPA and BP could greatly improve the photosensitivity of CEPS cationic photosensitive system. The optimal quantity of isopropanol added to the system was not more than 2 wt.%.

  15. Study on cationic photopolymerization reaction of epoxy polysiloxane

    International Nuclear Information System (INIS)

    The effects of epoxy monomers, concentration of photoinitiator and radical photoinitiators on the photosensitive properties of cationic phopolymerization system with a novel epoxy polysiloxane oligomer (CEPS) were investigated via a gel yield method. The results showed that among the tested epoxy monomers, the reactivity of ERL-4221 with cycloaliphatic epoxy groups was the highest. The optimum concentration of diaryldiodonium salt (SR-1012) was determined as 4-5 wt.%. Increasing the amounts of ERL-4221 in the CEPS cationic photopolymerization system, UV-curing rate increased. Radical photoinitiators with ArC=O structure possessed sensitization capacity to the cationic photoinitiator SR-1012. The photosensitivity of the CEPS system could be up to 165 mJ/cm2. Adding a small amount of IPA and BP could greatly improve the photosensitivity of CEPS cationic photosensitive system. The optimal quantity of isopropanol added to the system was not more than 2 wt.%

  16. Synthesis, Characterization and Ion Exchange Properties of Lithium Zirconium Silicate as Inorganic Ion Exchanger

    International Nuclear Information System (INIS)

    A new three components inorganic ion exchange material lithium zirconium silicate (Li Zr Si) has been synthesized by adding a mixture of lithium hydroxide (LiOH)and zirconium oxychloride (ZrOCI2) to sodium metasilicate (Na2Si O3) in different volume ratios. the synthesized materials ratios I,II and III have been characterize on the basis of chemical composition, X-ray fluorescence, X-ray diffraction, fourier transform infrared spectroscopy (FTIR) and thermal analysis . from the data obtained the synthesized different ratios of lithium zirconium silicates can be written as (Zr O)2 Li2 (SiO3)3. 10.7H2O, (Zr O) Li2(SiO3)2-5.3H2O and (Zr o)Li4 (SiO3)3- 4.4 H2O with amorphous structure. The chemical stability of the materials has been tested in water and acidic media. The ion exchange capacities of these materials for Na+, K+and Cs+ ions have been found to take the order Na+>K+>Cs+for all synthesized materials and depend on the crystal ionic radii of exchanging cations

  17. Synthesis, Characterization and Ion Exchange Properties of Lithium Zirconium Silicate as Inorganic Ion Exchanger

    International Nuclear Information System (INIS)

    A new three components inorganic ion exchange material lithium zirconium silicate (LiZrSi) has been synthesized by adding a mixture of lithium hydroxide (LiOH) and zirconium oxychloride(ZrOCl2) to sodium metasilicate (Na2SiO3) at different ratios. The synthesized materials ratios I, II and III have been characterized on the basis of chemical composition, X-ray fluorescence, XRD, Fourier Transform Infrared Spectroscopy (FTIR) and thermal analysis. From the data obtained, the synthesized different ratios of lithium zirconium silicates can be written as (ZrO)2Li2(SiO3)3. 10.7H2O, (ZrO)Li2(SiO3)2. 5.3H2O and (ZrO)Li4(SiO3.3. 4.4H2O with amorphous structure. The solubility of the materials has been tested in water and acidic media. The ion exchange capacities of these materials for Na+, K+ and Cs+ ions have been found to take the order Na+ > K+ > Cs+ for all synthesized materials and depend on the ionic radii of exchanging cations

  18. Bitstream - Capacity Building for Innovation : Final report

    OpenAIRE

    Söderström, Mikael; Hedestig, Ulf; Fallmyr, Terje; Ellingsen, Kjell; Hegerholm, Hallstein; Klæboe, Geir-Tore

    2014-01-01

    The main objective of the Bitstream project was to create a transnational platform for capacity building and exchange of experiences in the area of innovative business development. This includes capacity building for staff in the public sector in Norway and Sweden. The project deliverables has been to accomplish A virtual and physical transnational platform for capacity building that includes a cross-border exchange of experiences, research and developments in innovative business development....

  19. Gas-phase folding and unfolding of cytochrome c cations.

    OpenAIRE

    Wood, T D; Chorush, R A; Wampler, F M; Little, D P; O'Connor, P B; McLafferty, F. W.

    1995-01-01

    Water is thought to play a dominant role in protein folding, yet gaseous multiply protonated proteins from which the water has been completely removed show hydrogen/deuterium (H/D) exchange behavior similar to that used to identify conformations in solution. Indicative of the gas-phase accessibility to D2O, multiply-charged (6+ to 17+) cytochrome c cations exchange at six (or more) distinct levels of 64 to 173 out of 198 exchangeable H atoms, with the 132 H level found at charge values 8+ to ...

  20. Ion exchange synthesis and thermal characteristics of some $[\\text{N}^{+}_{2222}]$ based ionic liquids

    Indian Academy of Sciences (India)

    Vasishta D Bhatt; Kuldip Gohil

    2013-11-01

    Eight salts were obtained by reacting tetraethylammonium cation $[\\text{N}^{+}_{2222}]$ with inorganic anions like BF$^{-}_{4}$, NO$^{-}_{3}$, NO$^{-}_{2}$, SCN-, BrO$^{-}_{3}$, IO$^{-}_{3}$, PF$^{-}_{6}$ and HCO$^{-}_{3}$ using ion exchange method. These ionic liquids (ILs) were characterized using thermal methods, infrared spectroscopy and densitometry. Thermophysical properties such as density, coefficient of volume expansion, heat of fusion, heat capacity and thermal energy storage capacity were determined. Thermal conductivity of the samples was determined both in solid and liquid phases. Owing to high values of thermal energy storage capacity coupled with handsome liquid phase thermal conductivity, ILs under investigation were recommended as materials for thermal energy storage (TES) as well as heat transfer applications.

  1. [Preparation of spherical lignin cation adsorption resin with black pulping liquor].

    Science.gov (United States)

    Liu, Ming-Hua; Zou, Jin-Guang; Hong, Shu-Nan; Zeng, Zhen-Ou

    2005-09-01

    Spherical lignin cation adsorption resin was obtained by two-step method with black liquor of paper mill and characterized by the Scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). Firstly, the spherical lignin beads were prepared with black liquor of paper mill by applying reverse-phase suspension polymerization technique, and the preparation conditions were also optimized. The suitable conditions include 200 r/min of stirring speed, 90 degrees C of reaction temperature, 1.0 h of reaction time and use epoxy chloropropane (1.5% by weight of lignin) as cross-linking agent, the ideal volume ratio between oil phase and water phase was 3:1 by using kerosene oil as disperse phase, and the perfect dispersant agent was Tween 80 (3% by weight of lignin). Secondly, the spherical lignin cation adsorption resin was developed by grafting the acrylamide onto the back-bone of the spherical lignin beads. The best concentration of acrylamide was 0.72 mol/L at ambient temperature for 2.0 h, and the ideal initiator system was the Fenton reagent of H2O2/Fe2+. Under the above conditions, the ion exchange capacity of the prepared resin could reach 1.640 5 mmol/g. PMID:16366482

  2. Influence of organic matter type and medium composition on the sorption affinity of C12-benzalkonium cation.

    Science.gov (United States)

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

    2013-08-01

    We used the 7-μm polyacrylate ion-exchange SPME fibers to investigate C12-benzalkonium sorption to 10 mg/L natural organic matter at concentrations well below the cation-exchange capacity. C12-BAC sorption at constant medium conditions differed within 0.4 log units for two humic acids (Aldrich, Leonardite) and peat (Sphagnum, Pahokee), with similar nonlinear sorption isotherms (KF ∼ 0.8). Sorption to the SPME fibers and Aldrich humic acid (AHA) was reduced at both low pH and high electrolyte concentration, and reduced more strongly by Ca²⁺ compared with Na⁺ at similar concentrations. Sorption isotherms for AHA (5-50-500 mM Na⁺, pH 6) was modeled successfully by the NICA-Donnan approach, resulting in an intrinsic sorption coefficient of 5.35 (Caq = 1 nM). The NICA-Donnan model further explained the stronger specific binding of Ca²⁺ compared to Na⁺ by differences in Boltzmann factors. This study provides relevant information to interpret bioavailability of quaternary ammonium compounds, and possibly for other organic cations. PMID:23676325

  3. Copper cation removal in an electrokinetic cell containing zeolite.

    Science.gov (United States)

    Elsayed-Ali, Omar H; Abdel-Fattah, Tarek; Elsayed-Ali, Hani E

    2011-01-30

    Zeolites are used in environmental remediation of soil or water to immobilize or remove toxic materials by cation exchange. An experiment was conducted to test the use a low electric field to direct the toxic cations towards the zeolite. An electrokinetic cell was constructed using carbon electrodes. Synthetic Linde Type A (LTA) zeolite was placed in the cell. Copper(II) chloride dissolved in water was used as a contaminant. The Cu(2+) concentration was measured for ten hours with and without an applied electric field. The removal of the Cu(2+) ions was accelerated by the applied field in the first two hours. For longer time, the electric field did not improve the removal rate of the Cu(2+) ions. The presence of zeolite and applied electric field complicates the chemistry near the cathode and causes precipitation of Cu(2+) ions as copper oxide on the surface of the zeolite. With increased electric field the zeolite farther away from the cathode had little cation exchange due to the higher drift velocity of the Cu(2+) ions. The results also show that, in the LTA Zeolite A pellets, the cation exchange of Cu is limited to a shell of several tens of micrometers. PMID:21109348

  4. Continuous elimination of Pb{sup 2+}, Cu{sup 2+}, Zn{sup 2+}, H{sup +} and NH{sub 4}{sup +} from acidic waters by ionic exchange on natural zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, Benjamin [E.T.S. Ingenieros de Minas, Universidad Politecnica de Madrid, Rios Rosas 21, 28003 Madrid (Spain); Canoira, Laureano, E-mail: laureano.canoira.lopez@upm.es [E.T.S. Ingenieros de Minas, Universidad Politecnica de Madrid, Rios Rosas 21, 28003 Madrid (Spain); Morante, Fernando, E-mail: fmorante@espol.edu.ec [Instituto de Ciencias Quimicas y Ambientales, Escuela Superior Politecnica del Litoral, P.O. Box 09-01-5863, Guayaquil (Ecuador); Martinez-Bedia, Jose M.; Vinagre, Carlos; Garcia-Gonzalez, Jeronimo-Emilio [E.T.S. Ingenieros de Minas, Universidad Politecnica de Madrid, Rios Rosas 21, 28003 Madrid (Spain); Elsen, Jan, E-mail: jan.elsen@geo.kuleuven.be [Physico-Chemische Geologie, Katholieke Universiteit Leuven, Celestijnenlaan 200E, B-3001, Heverlee (Belgium); Alcantara, Ramon [E.T.S. Ingenieros de Minas, Universidad Politecnica de Madrid, Rios Rosas 21, 28003 Madrid (Spain)

    2009-07-30

    A study of breakthrough curves for cations usually found in acid mine drainage (Pb{sup 2+}, Cu{sup 2+}, Zn{sup 2+} and H{sup +}) and municipal wastewater (NH{sub 4}{sup +}) have been conducted on some natural zeolitic tuffs. The zeolitic tuffs used in this study are: three zeolitic tuffs from Cayo Formation, Guayaquil (Ecuador), characterized by X-ray diffraction as clinoptilolite (sample CLI-1) and heulandite (samples HEU-1 and HEU-2)-rich tuffs, and two zeolitic tuffs from Parnaiba Basin, Belem do Para (Brazil), characterized as stilbite-rich tuffs (samples STI-1 and STI-2). The clinoptilolite sample CLI-1 shows an exceedingly good exchange capacities for Pb{sup 2+} and NH{sub 4}{sup +} as received, and also a very high exchange capacity for Cu{sup 2+} and Zn{sup 2+} when conditioned with 2 M sodium chloride, with much higher values than those reported in the literature for other clinioptilolite ores. A general order of effective cation exchange capacity could be inferred from breakthrough curves on these zeolitic tuffs: CLI-1>HEU-2>HEU-1>STI-2 Since it is true for most of the cations studied.

  5. Long-term tobacco plantation induces soil acidification and soil base cation loss.

    Science.gov (United States)

    Zhang, Yuting; He, Xinhua; Liang, Hong; Zhao, Jian; Zhang, Yueqiang; Xu, Chen; Shi, Xiaojun

    2016-03-01

    Changes in soil exchangeable cations relative to soil acidification are less studied particularly under long-term cash crop plantation. This study investigated soil acidification in an Ali-Periudic Argosols after 10-year (2002-2012) long-term continuous tobacco plantation. Soils were respectively sampled at 1933 and 2143 sites in 2002 and 2012 (also 647 tobacco plants), from seven tobacco plantation counties in the Chongqing Municipal City, southwest China. After 10-year continuous tobacco plantation, a substantial acidification was evidenced by an average decrease of 0.20 soil pH unit with a substantial increase of soil sites toward the acidic status, especially those pH ranging from 4.5 to 5.5, whereas 1.93 kmol H(+) production ha(-1) year(-1) was mostly derived from nitrogen (N) fertilizer input and plant N uptake output. After 1 decade, an average decrease of 27.6 % total exchangeable base cations or of 0.20 pH unit occurred in all seven tobacco plantation counties. Meanwhile, for one unit pH decrease, 40.3 and 28.3 mmol base cations kg(-1) soil were consumed in 2002 and 2012, respectively. Furthermore, the aboveground tobacco biomass harvest removed 339.23 kg base cations ha(-1) year(-1) from soil, which was 7.57 times higher than the anions removal, leading to a 12.52 kmol H(+) production ha(-1) year(-1) as the main reason inducing soil acidification. Overall, our results showed that long-term tobacco plantation not only stimulated soil acidification but also decreased soil acid-buffering capacity, resulting in negative effects on sustainable soil uses. On the other hand, our results addressed the importance of a continuous monitoring of soil pH changes in tobacco plantation sites, which would enhance our understanding of soil fertility of health in this region. PMID:26566613

  6. A lanthanide complex for metal encapsulations and anion exchanges.

    Science.gov (United States)

    Sun, Yan-Qiong; Wan, Fang; Li, Xin-Xiong; Lin, Jian; Wu, Tao; Zheng, Shou-Tian; Bu, Xianhui

    2016-08-01

    A cationic lanthanide metalloligand with 3 dangling carboxylate groups on its periphery co-assembles with nitrate into a porous thermochromic solid responsive to both external cations and anions, owing to the presence of exchangeable NO3(-) as well as cation cavities arising from cooperative orientation of free carboxylate groups. An especially interesting feature is the structural memory effect during crystallization exhibited by the metalloligand, even after dissolution and binding to secondary cations (Cu(2+), Cd(2+)…). Moreover, the porous solid can undergo ion-exchange with various anions, leading to tunable thermochromic temperature and color range. PMID:27463609

  7. Effects of ionizing radiation on modern ion exchange materials

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, S.F.; Pillay, K.K.S.

    1993-10-01

    We review published studies of the effects of ionizing radiation on ion exchange materials, emphasizing those published in recent years. A brief overview is followed by a more detailed examination of recent developments. Our review includes styrene/divinylbenzene copolymers with cation-exchange or anion-exchange functional groups, polyvinylpyridine anion exchangers, chelating resins, multifunctional resins, and inorganic exchangers. In general, strong-acid cation exchange resins are more resistant to radiation than are strong-base anion exchange resins, and polyvinylpyridine resins are more resistant than polystyrene resins. Cross-linkage, salt form, moisture content, and the surrounding medium all affect the radiation stability of a specific exchanger. Inorganic exchangers usually, but not always, exhibit high radiation resistance. Liquid ion exchangers, which have been used so extensively in nuclear processing applications, also are included.

  8. Effects of ionizing radiation on modern ion exchange materials

    International Nuclear Information System (INIS)

    We review published studies of the effects of ionizing radiation on ion exchange materials, emphasizing those published in recent years. A brief overview is followed by a more detailed examination of recent developments. Our review includes styrene/divinylbenzene copolymers with cation-exchange or anion-exchange functional groups, polyvinylpyridine anion exchangers, chelating resins, multifunctional resins, and inorganic exchangers. In general, strong-acid cation exchange resins are more resistant to radiation than are strong-base anion exchange resins, and polyvinylpyridine resins are more resistant than polystyrene resins. Cross-linkage, salt form, moisture content, and the surrounding medium all affect the radiation stability of a specific exchanger. Inorganic exchangers usually, but not always, exhibit high radiation resistance. Liquid ion exchangers, which have been used so extensively in nuclear processing applications, also are included

  9. Method of decomposing radioactive spent ion exchange resins

    International Nuclear Information System (INIS)

    Purpose: To improve the decomposability of spent ion exchange resins such as anionic resins, anionic - cationic mixed resins or the likes issued from nuclear power plants. Method: Spent ion exchange resins containing radioactive materials are decomposed by hydrogen peroxide. In this case, anionic exchange resins or mixture of anionic exchange resins and cationic exchange resins are decomposed by using bivalent or trivalent iron ions coexistent with sulfate groups in excess of the amount corresponding to the molar amount of bivalent or trivalent iron ions as a catalyst. Since the anionic exchange resins or the mixture of the anionic exchange resins and cationic resins are decomposed substantially completely, the amount of residue after the decomposition is reduced and the volume-reducing property of the radioactive wastes can be improved to facilitate the solidifying treatment. (Moriyama, K.)

  10. Heavy metals retention capacity of a non-conventional sorbent developed from a mixture of industrial and agricultural wastes.

    Science.gov (United States)

    Agouborde, Lina; Navia, Rodrigo

    2009-08-15

    Zinc and copper removal from aqueous solutions using brine sediments (industrial residue), sawdust (agricultural residue) and the mixture of both materials has been researched through batch and column tests. Brine sediments were found to be mainly constituted by halite and calcite, while its main cations exchangeable were sodium, calcium, magnesium and potassium. In sawdust the main exchangeable cations detected were calcium, magnesium, sodium and potassium. FT-IR spectra of sawdust and brine sediment-sawdust mixture showed that brine sediments produced important changes in carboxylic, alcoholic and phenolic groups present in the sawdust. The maximum zinc adsorption capacity was found to be 4.85, 2.58 and 5.59 mg/g using an adsorbent/solution ratio of 1/40, for brine sediments, sawdust and the mixture, respectively. For copper, the maximum adsorption capacity was found to be 4.69, 2.31 and 4.33 mg/g, using adsorbent/solution ratios of 1/40, for brine sediments, sawdust and the mixture, respectively. Maximum copper adsorption capacity of the mixture, on the contrary to zinc adsorption, was lightly inferior to maximum adsorption capacity obtained in brine sediments. Adsorption isotherms data adjusted better to the Langmuir model. Additionally, columns reached the saturation point at 690 min for zinc and 360 min for copper. The main mechanism involved in the removal of both metals may be the ionic exchange between sodium and calcium ions present in brine sediments and H(+) present in functional groups of sawdust. The use of brine sediments, sawdust and their mixture, presents an interesting option both, for wastewater decontamination (as a possible non-conventional sorbent for the removal of heavy metals) and as a waste recycling option. PMID:19188023

  11. Disposal of heavy metal cations in aqueous media by adsorption on coal to Ghazni

    Directory of Open Access Journals (Sweden)

    О.М. Заславський

    2008-03-01

    Full Text Available  Adsorption of Pb and Cu cations and their mixture on the surface of modified and non-modified anti-gas coal trough different time intervals have been studied. The maximum adsorption capacity of coal relative to each cations have been determined. Absence  of concurrence between cations of Pb and Cu during adsorption from mixture is explained by difference of  types of their interaction with coal surface. The high effectiveness and perspectivities of application of anti-gas coal for neutralization of heavy metal cations in aqueous solution was shown.

  12. Biosorption of radiocesium by deinococcus radiodurans influenced by cations

    International Nuclear Information System (INIS)

    Deinococcus radiodurans has a strong ability to withstand high doses of radiation, which makes it as an ideal candidate for bioremediation of sites contaminated with radionuclides and toxic chemicals. However, no data is available on whether D. radiodurans has a specific sorption capacity to radiocesium for bioremediation purpose. The radiocesium biosorption capacity of live cells of D. radiodurans in the presence of other interfering cations was investigated. The maximum biosorption capacity of radiocesium by D. radiodurans in equilibrium state was about 2,100 kBq/kg (fresh weight basis). Among the tested monovalent cations, NH4+ had the strongest antagonism on 134Cs biosorption for D. radiodurans. However, this antagonism could only be observed at a concentration as high as 100 mmol/L. Divalent cations, such as Ca2+ and Pb2+ could reduced the biosorption of radiocesium by D. radiodurans. Al3+ and Cr3+ were cytotoxic to D. radiodurans cells, the growth of D. radiodurans cells was inhibited when the concentrations of these cations were greater than 1 mmol/L. (authors)

  13. [Antioxidant activity of cationic whey protein isolate].

    Science.gov (United States)

    titova, M E; Komolov, S A; Tikhomirova, N A

    2012-01-01

    The process of lipid peroxidation (LPO) in biological membranes of cells is carried out by free radical mechanism, a feature of which is the interaction of radicals with other molecules. In this work we investigated the antioxidant activity of cationic whey protein isolate, obtained by the cation-exchange chromatography on KM-cellulose from raw cow's milk, in vitro and in vivo. In biological liquids, which are milk, blood serum, fetal fluids, contains a complex of biologically active substances with a unique multifunctional properties, and which are carrying out a protective, antimicrobial, regenerating, antioxidant, immunomodulatory, regulatory and others functions. Contents of the isolate were determined electrophoretically and by its biological activity. Cationic whey protein isolate included lactoperoxidase, lactoferrin, pancreatic RNase, lysozyme and angeogenin. The given isolate significantly has an antioxidant effect in model experimental systems in vitro and therefore may be considered as a factor that can adjust the intensity of lipid oxidation. In model solutions products of lipid oxidation were obtained by oxidation of phosphatidylcholine by hydrogen peroxide in the presence of a source of iron. The composition of the reaction mixture: 0,4 mM H2O2; 50 mcM of hemin; 2 mg/ml L-alpha-phosphatidylcholine from soybean (Sigma, German). Lipid peroxidation products were formed during the incubation of the reaction mixture for two hours at 37 degrees C. In our studies rats in the adaptation period immediately after isolation from the nest obtained from food given orally native cationic whey protein isolate at the concentration three times higher than in fresh cow's milk. On the manifestation of the antioxidant activity of cationic whey protein isolate in vivo evidence decrease of lipid peroxidation products concentration in the blood of rats from the experimental group receipt whey protein isolate in dos 0,6 mg/g for more than 20% (pwhey protein isolate has an

  14. Mercury release from deforested soils triggered by base cation enrichment.

    Science.gov (United States)

    Farella, N; Lucotte, M; Davidson, R; Daigle, S

    2006-09-01

    The Brazilian Amazon has experienced considerable colonization in the last few decades. Family agriculture based on slash-and-burn enables millions of people to live in that region. However, the poor nutrient content of most Amazonian soils requires cation-rich ashes from the burning of the vegetation biomass for cultivation to be successful, which leads to forest ecosystem degradation, soil erosion and mercury contamination. While recent studies have suggested that mercury present in soils was transferred towards rivers upon deforestation, little is known about the dynamics between agricultural land-use and mercury leaching. In this context, the present study proposes an explanation that illustrates how agricultural land-use triggers mercury loss from soils. This explanation lies in the competition between base cations and mercury in soils which are characterized by a low adsorption capacity. Since these soils are naturally very poor in base cations, the burning of the forest biomass suddenly brings high quantities of base cations to soils, destabilizing the previous equilibrium amongst cations. Base cation enrichment triggers mobility in soil cations, rapidly dislocating mercury atoms. This conclusion comes from principal component analyses illustrating that agricultural land-use was associated with base cation enrichment and mercury depletion. The overall conclusions highlight a pernicious cycle: while soil nutrient enrichment actually occurs through biomass burning, although on a temporary basis, there is a loss in Hg content, which is leached to rivers, entering the aquatic chain, and posing a potential health threat to local populations. Data presented here reflects three decades of deforestation activities, but little is known about the long-term impact of such a disequilibrium. These findings may have repercussions on our understanding of the complex dynamics of deforestation and agriculture worldwide. PMID:16781764

  15. 基于温度和热容流率同时变化的有分流换热网络弹性设计的研究%Synthesis of Flexible Heat Exchanger Networks with Stream Splits Based on Rangers of Stream Supply Temperatures and Heat Capacity Flowrates

    Institute of Scientific and Technical Information of China (English)

    李志红; 罗行; 华贲; W.Roetzel

    2004-01-01

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

  16. Desalination by electrodialysis with the ion-exchange membrane prepared by radiation-induced graft polymerization

    International Nuclear Information System (INIS)

    Ion-exchange membranes modified with the triethylamine [-N(CH2CH3)3] and phosphoric acid (-PO3 H) groups were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto the polyolefin nonwavon fabric (PNF) and subsequent chemical modification of poly(GMA) graft chains. The physical and chemical properties of the GMA-grafted PNF and the PNF modified with ion-exchange groups were investigated by SEM, XPS, TGA, and DSC. Furthermore, electrochemical properties such as specific electric resistance, transport number of K+, and desalination were examined. The grafting yield increased with increasing reaction time and reaction temperature. The maximum grafting yield was obtained with 40% (vol.%) monomer concentration in dioxane at 60 deg. C. The content of the cation- and anion-exchange group increased with increasing grafting yield. Electrical resistance of the PNF modified with TEA and -PO3 H group decreased, while the water uptake (%) increased with increasing ion-exchange group capacities. Transport number of the PNF modified with ion-exchange group were the range of ca. 0.82-0.92. The graft-type ion-exchange membranes prepared by radiation-induced graft copolymerization were successfully applied as separators for electrodialysis. (author)

  17. Desalination by electrodialysis with the ion-exchange membrane prepared by radiation-induced graft polymerization

    Science.gov (United States)

    Choi, Seong-Ho; Han Jeong, Young; Jeong Ryoo, Jae; Lee, Kwang-Pill

    2001-01-01

    Ion-exchange membranes modified with the triethylamine [-N(CH 2CH 3) 3] and phosphoric acid (-PO 3 H) groups were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto the polyolefin nonwavon fabric (PNF) and subsequent chemical modification of poly(GMA) graft chains. The physical and chemical properties of the GMA-grafted PNF and the PNF modified with ion-exchange groups were investigated by SEM, XPS, TGA, and DSC. Furthermore, electrochemical properties such as specific electric resistance, transport number of K +, and desalination were examined. The grafting yield increased with increasing reaction time and reaction temperature. The maximum grafting yield was obtained with 40% (vol.%) monomer concentration in dioxane at 60°C. The content of the cation- and anion-exchange group increased with increasing grafting yield. Electrical resistance of the PNF modified with TEA and -PO 3 H group decreased, while the water uptake (%) increased with increasing ion-exchange group capacities. Transport number of the PNF modified with ion-exchange group were the range of ca. 0.82-0.92. The graft-type ion-exchange membranes prepared by radiation-induced graft copolymerization were successfully applied as separators for electrodialysis.

  18. Morphology of sulfonated polyimide ionomers from ESR spectra of paramagnetic transition metal cations and nitroxide spin probes

    International Nuclear Information System (INIS)

    We present a study of sulfonated polyimide block ionomer membranes (SPIs) in the dry state, and swollen by water, methanol, ethanol, and dioxane. The ionomers are based on a naphthalenic dianhydride, and differ in the ionic exchange capacity and the type of diamine in the hydrophobic block. The ionomers were studied by electron spin resonance (ESR) spectroscopy of the paramagnetic transition metal cations Cu+ and VO2+, and of two nitroxide spin probes. The results indicated the existence of separate hydrophobic and hydrophilic domains in the dry and in the swollen membranes. Water clusters with a diameter + or K+. The irreversible increase of the signal intensity upon heating of the dry membranes above 360 K suggests the formation of reactive intermediates that may be involved in ionomer degradation processes. (author)

  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 as the...

  20. Electrically switched cesium ion exchange. FY 1996 annual report

    International Nuclear Information System (INIS)

    An electrochemical method for metal ion separations, called Electrically Switched Ion Exchange, is described. Direct oxidation and reduction of an electroactive film attached to an electrode surface is used to load and unload the film with alkali metal cations. The electroactive films under investigation are Ni hexacyanoferrates, which are deposited on the surface by applying an anodic potential to a Ni electrode in a solution containing the ferricyanide anion. Reported film preparation procedures were modified to produce films with improved capacity and stability. Electrochemical behavior of the derivatized electrodes were investigated using cyclic voltammetry and chronocoulometry. The films show selectivity for Cs in concentrated sodium solutions. Raman spectroscopy was used to monitor changes in oxidation state of the film and imaging experiments have demonstrated that the redox reactions are spatially homogenous across the film. Requirements for a bench scale unit were identified

  1. Catalysis using hydrous metal oxide ion exchangers

    Science.gov (United States)

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  2. Catalysis using hydrous metal oxide ion exchanges

    Science.gov (United States)

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  3. Removal of charged micropollutants from water by ion-exchange polymers -- effects of competing electrolytes.

    Science.gov (United States)

    Bäuerlein, Patrick S; Ter Laak, Thomas L; Hofman-Caris, Roberta C H M; de Voogt, Pim; Droge, Steven T J

    2012-10-15

    A wide variety of environmental compounds of concern, e.g. pharmaceuticals or illicit drugs, are acids or bases that may predominantly be present as charged species in drinking water sources. These charged micropollutants may prove difficult to remove by currently used water treatment steps (e.g. UV/H(2)O(2), activated carbon (AC) or membranes). We studied the sorption affinity of some ionic organic compounds to both AC and different charged polymeric materials. Ion-exchange polymers may be effective as additional extraction phases in water treatment, because sorption of all charged compounds to oppositely charged polymers was stronger than to AC, especially for the double-charged cation metformin. Tested below 1% of the polymer ion-exchange capacity, the sorption affinity of charged micropollutants is nonlinear and depends on the composition of the aqueous medium. Whereas oppositely charged electrolytes do not impact sorption of organic ions, equally charged electrolytes do influence sorption indicating ion-exchange (IE) to be the main sorption mechanism. For the tested polymers, a tenfold increased salt concentration lowered the IE-sorption affinity by a factor two. Different electrolytes affect IE with organic ions in a similar way as inorganic ions on IE-resins, and no clear differences in this trend were observed between the sulphonated and the carboxylated cation-exchanger. Sorption of organic cations is five fold less in Ca(2+) solutions compared to similar concentrations of Na(+), while that of anionic compounds is three fold weaker in SO(4)(2-) solutions compared to equal concentrations of Cl(-). PMID:22818952

  4. Probing Capacity

    CERN Document Server

    Asnani, Himanshu; Weissman, Tsachy

    2010-01-01

    We consider the problem of optimal probing of states of a channel by transmitter and receiver for maximizing rate of reliable communication. The channel is discrete memoryless (DMC) with i.i.d. states. The encoder takes probing actions dependent on the message. It then uses the state information obtained from probing causally or non-causally to generate channel input symbols. The decoder may also take channel probing actions as a function of the observed channel output and use the channel state information thus acquired, along with the channel output, to estimate the message. We refer to the maximum achievable rate for reliable communication for such systems as the 'Probing Capacity'. We characterize this capacity when the encoder and decoder actions are cost constrained. To motivate the problem, we begin by characterizing the trade-off between the capacity and fraction of channel states the encoder is allowed to observe, while the decoder is aware of channel states. In this setting of 'to observe or not to o...

  5. Cation exchange and adsorption on clays and clay minerals

    OpenAIRE

    Ammann, Lars

    2003-01-01

    The specific surface area of a clay mineral comprises the external and internal surface area and, finally, the surface area which is exposed to the solution (Chap. 6.1). The aim of this study was to correlate adsorption data of common clays with these specific surface areas.

  6. Sulfonated hydrocarbon graft architectures for cation exchange membranes

    DEFF Research Database (Denmark)

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

    2013-01-01

    to various degrees. Series of grafting densities and graft lengths are prepared, and membranes are solvent cast from DMSO. The membrane properties in aqueous environments are evaluated from their water swelling behavior, and their thermal properties and stability are investigated by thermogravimetric...

  7. The influence of acid treatments over vermiculite based material as adsorbent for cationic textile dyestuffs.

    Science.gov (United States)

    Stawiński, Wojciech; Freitas, Olga; Chmielarz, Lucjan; Węgrzyn, Agnieszka; Komędera, Kamila; Błachowski, Artur; Figueiredo, Sónia

    2016-06-01

    The influence of different acid treatments over vermiculite was evaluated. Equilibrium, kinetic and column studies have been conducted. The results showed that vermiculite first treated with nitric acid and then with citric acid has higher adsorption capacity, presenting maximum adsorption capacities in column experiments: for Astrazon Red (AR), 100.8 ± 0.8 mg g(-1) and 54 ± 1 mg g(-1) for modified and raw material, respectively; for Methylene Blue (MB) 150 ± 4 mg g(-1) and 55 ± 2 mg g(-1) for modified and raw material, respectively. Materials characterization by X-ray diffraction, UV-vis-diffuse reflectance spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, X-ray fluorescence, N2 adsorption and CEC determination, has been performed. The results suggest the existence of exchange of interlayer cations, leaching of metals from vermiculite's sheets and formation of an amorphous phase in the material. Adsorption follows pseudo 2(nd) order model kinetics for both dyestuffs and equilibrium occurs accordingly to Langmuir's model for AR and Freundlich's model for MB. In column systems Yan's model is the best fit. The enhanced properties of acid treated vermiculite offer new perspectives for the use of this adsorbent in wastewater treatment. PMID:27015571

  8. Biocompatibility of Cation Coated on Plasma-Polymerized Ti Surface

    Science.gov (United States)

    Lee, Kang; Ko, Yeong-Mu; Kim, Byung-Hoon

    2012-08-01

    In this study, we investigated the bone formation properties and cell responses on Na-, Mg-, K-, and Ca-ion-exchanged carboxyl plasma polymerized titanium (Ti) surfaces. The phase and morphologies of deposits bonelike apatite were significantly influence by the cation species. Na and Mg ions promote bonelike apatite nucleation and growth on plasma-functionalized Ti surfaces in simulated body fluid (SBF) and improves the crystallinity of the bonelike apatite deposited layer. The cell viability tests revealed significantly enhanced viability on the Ca-ion-exchanged plasma-functionalized Ti surface than on any other surface.

  9. Characterization of UO22+ exchanged Y zeolite

    International Nuclear Information System (INIS)

    The present study discusses the incorporation of uranyl ion into Y-zeolite framework. The UO22+ sorption was measured by neutron activation analyses. The Y-zeolite framework distorts in response to the cations present in the structure. Hence, depending on the amount and the location of the exchanged cations, the features of the X-ray diffraction pattern may vary. From the Rietveld analysis of these patterns, the positions occupied by the UO22+ cations in the zeolite network were determined. (author)

  10. Metal cations inserted in vanadium-oxide nanotubes

    International Nuclear Information System (INIS)

    Vanadium-oxide nanotubes (VO x-NTs) consist of nanosize cylinders of thin, easily bent vanadyl (VO x) wall chains, which are open at both ends. Surfactant molecules (e.g. C12H27N) can be easily trapped in the interior of the nanotube walls. The structure of as-synthesized VO x-NTs are observed to collapse to an amorphous vanadium oxide at temperatures greater than 250 deg, C. This happens, even under a protective atmosphere. This property makes the VO x-NTs unusable as a catalyst at temperatures between 400-500 deg, C, which is the temperature range where many applications would exist. In order to increase the thermal stability of VO x-NTs several exchange reactions have been used to modify the original nanotubes. In these reactions metallic cations (Cd2+, Co2+, Mn2+ or Zn2+) were introduced. It was observed that that the morphology of the nanotubes remained unchanged after the exchange reactions were performed. In order to characterize the exchanged VO x-NTs the following analytic techniques were used: scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared, particle-induced X-ray emission and Rutherford backscattering spectrometry. The results showed that the VO x-NTs exchanged with metallic cations have preserved their tubular morphology. However, it has not been possible to fully perform a 100% efficient exchange reaction

  11. Ion exchange separation for decontamination of centrifuge enrichment plant

    International Nuclear Information System (INIS)

    Ion exchange separation of uranyl ion (UO22+) from metal cations has been carried out by the columnar operation using ion exchange resins in 0.1 mol/dm3 sulfuric acid medium. Uranyl ion was adsorbed in an anion exchange resin and the rest metal cations, Fe(III), Al(III), Cr(III), Ni(II) and Cu(II) ions, were adsorbed in a cation exchange resin in this system. Desorption of uranyl ion and metal cations adsorbed in the resins were tested by 2 mol/dm3 sulfuric acid solution. Desorbed elements were confirmed to be precipitated by appropriate alkaline solutions. On the basis of the results obtained, a concept was made on a decontamination system for uranium-contaminated waste solution from centrifuge enrichment plant. (author)

  12. Capacity Building

    International Nuclear Information System (INIS)

    Outcomes & Recommendations: • Significant increase needed in the nuclear workforce both to replace soon-to-retire current generation and to staff large numbers of new units planned • Key message, was the importance of an integrated approach to workforce development. • IAEA and other International Organisations were asked to continue to work on Knowledge Management, Networks and E&T activities • IAEA requested to conduct Global Survey of HR needs – survey initiated but only 50% of operating countries (30% of capacity) took part, so results inconclusive

  13. Experimental research on heat transfer in a coupled heat exchanger

    OpenAIRE

    Liu Yin; Ma Jing; Zhou Guang-Hui; Guan Ren-Bo

    2013-01-01

    The heat exchanger is a devise used for transferring thermal energy between two or more different temperatures. The widespreadly used heat exchanger can only achieve heat exchange between two substances. In this paper, a coupled heat exchanger is proposed, which includes a finned heat exchanger and a double pipe heat exchanger, for multiple heat exchange simultaneously. An experiment is conducted, showing that the average heating capacity increases more tha...

  14. Liquid-solid extraction of cationic metals by cationic amphiphiles

    International Nuclear Information System (INIS)

    In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl-, NO3-, C2O42-) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu2+, Zn2+, UO22+, Fe3+, Nd3+, Eu3+, Th4+) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author)

  15. Cationic nanofibrillar cellulose with high antibacterial properties.

    Science.gov (United States)

    Chaker, Achraf; Boufi, Sami

    2015-10-20

    Cationic nanofibrillar cellulose (C-NFC) has been prepared via a high pressure homogenization using quaternized cellulose fibers with glycidyltrimethylammonium chloride. It has been shown that the quaternization of dried softwood pulp facilitated the defibrillation processes and prevented clogging of the homogenizer. The effects of the trimethylammonium chloride content on the fibrillation yield, the transparency degree of the gel, the rheological behavior of the NFC suspension and their electrokinetic properties were investigated. AFM observation showed that the NFC suspension consisted of individualized cellulose I nanofibrils 4-5nm in width and length in the micronic scale. In addition to their strong reinforcing potential, the inclusion of C-NFC into a polymer matrix was shown to efficiently enhance the antibacterial activity. The reinforcing potential of C-NFC, studied by dynamic mechanical analysis (DMA), was compared to anionic NFC and the difference was explained in terms of the nanofibrils capacities to build up a strong networks held by hydrogen bonding. PMID:26256179

  16. Test procedure for anion exchange chromatography

    International Nuclear Information System (INIS)

    Plutonium from stored nitrate solutions will be sorbed onto anion exchange resins and converted to storable plutonium dioxide. Useful information will be simultaneously gained on the thermal stability and ion exchange capacity of four commercially available anion exchange resins over several years and under severe degradative conditions. This information will prove useful in predicting the safe and efficient lifetimes of these resins

  17. Stimulation of cation transport in mitochondria by gramicidin and truncated derivatives

    International Nuclear Information System (INIS)

    Gramicidin and the truncated derivatives desformylgramicidin (desfor) and des(formylvalyl)gramicidin (desval) stimulate monovalent cation transport in rat liver mitochondria. Cation fluxes were compared indirectly from the effect of cations on the membrane potential at steady state (state 4) or from the associated stimulation of electron transport. Rb+ transport was measured directly from the uptake of 86Rb. The truncated gramicidins show enhanced selectivity for K+ and Rb+ when compared to gramicidin. Moreover, the pattern of selectivity within the alkali cation series is altered. The cation fluxes through the truncated derivatives are more strongly dependent on the cation concentration. The presence of high concentrations of permeating cation enhances the transport of other cations through the truncated derivative channels, suggesting that cations are required for stabilizing the channel structure. In high concentrations of KCl, desfor and desval are nearly as effective as gramicidin in collapsing the mitochondrial membrane potential, and consequently, in the uncoupling of oxidative phosphorylation and enhancement of ATP hydrolysis. Preliminary experiments with liposomes show that 86Rb exchange is stimulated by desfor and desval almost to the same extend at gramicidin. These results strongly suggest that the truncated gramicidins form a novel conducting channel which differs from the gramicidin head-to-head, single-stranded β6.3-helical dimer (channel) in its conductance characteristic and its structure. On the basis of the secondary structure of the truncated derivatives, the authors suggest that the antiparallel double-stranded helix dimer (pore) is a likely alternative structure for this novel channel

  18. Immigration and Status Exchange in Australia and the United States

    OpenAIRE

    Choi, Kate H.; Tienda, Marta; Cobb-Clark, Deborah; Sinning, Mathias

    2011-01-01

    The claim that marriage is a venue for status exchange of achieved traits, like education, and ascribed attributes, notably race and ethnic membership, has regained traction in the social stratifi cation literature. Most studies that consider status exchanges ignore birthplace as a social boundary for status exchanges via couple formation. This paper evaluates the status exchange hypothesis for Australia and the United States, two Anglophone nations with long immigration traditions whose admi...

  19. Adsorption equilibrium of fructose, glucose and sucrose for cationic resins in the sodium and potassium form

    OpenAIRE

    Nobre, Clarisse; Santos, M. J.; Dominguez, Ana; Torres, Duarte; Peres, António M.; Rocha, Isabel; Ferreira, Eugénio C.; Rodrigues, Lígia R.; Teixeira, José A.

    2009-01-01

    Separation of glucose from mixtures of fructose and sucrose in molasses is a major challenge in industrial sugar chromatographic separations. The efficiency of a chromatographic process is largely dependent on the adsorbent used. Sulfonated poly(styrene-co-divinylbenzene) (PS-DVB) ion exchange resins are the most frequently used for sugars separation, generally in a cationic form. The cation will complex with the hydroxyl group of the sugar leading to a selective adsorption accord...

  20. Cationic speciation in nonaqueous media

    International Nuclear Information System (INIS)

    Electronic spectra of solutions of d transition elements in the superacids HF, H2SO4, HSO3F, and CF3SO3H and in chloroaluminate melts indicate that in acidic monaqueous media the elements are present as solvated cations, whereas in basic media the speciation is anionic, the same situation as in aqueous solutions. Further, in very highly acidic media, cations in very low oxidation states are stable (e.g., Ti2+), but these disproportionate on addition of base to the system. In this paper spectra, where available, of U, Np, and Pu in oxidation states III and IV in aqueous media, in protonic superacids, and in chloroaluminates are presented to postulate cationic speciation of these early actinides in highly acidic media

  1. A high-performance "sweeper" for toxic cationic herbicides: an anionic metal-organic framework with a tetrapodal cage.

    Science.gov (United States)

    Jia, Yan-Yuan; Zhang, Ying-Hui; Xu, Jian; Feng, Rui; Zhang, Ming-Shi; Bu, Xian-He

    2015-12-21

    This communication reports a novel metal-organic framework exhibiting an excellent performance in adsorbing small toxic cationic herbicides, i.e. methyl viologen and diquat, with large adsorption capacities and ultratrace residue levels. To the best of our knowledge, this is the first example of high-performance MOFs trapping toxic cationic herbicides. PMID:26468513

  2. 阳离子交换树脂催化制备纳米纤维素晶体的谱学性能与流变行为%Spectrum and Rheological Properties of Nanocellulose Crystal Prepared with Cation Exchange Resin

    Institute of Scientific and Technical Information of China (English)

    唐丽荣; 黄彪; 戴达松; 欧文; 李涛; 周东东; 陈学榕

    2011-01-01

    采用强酸型阳离子交换树脂在超声波辅助作用下制备了纳米纤维素晶体(NCC).采用场发射环境扫描电子显微镜(ESEM-FEG)、场发射透射电子显微镜(HR-TEM)、X射线粉末衍射仪(XRD)、傅利叶红外光谱仪(FT-IR)和转子式流变仪对所制备NCC的形貌、谱学和流变学行为进行了研究.结果表明,所制备NCC为近球形,颗粒尺寸约为25nm~50nm,样品属于纤维素Ⅰ型,结晶度为84.26%,晶粒平均由6个晶胞组成.由FT-IR分析可知,NCC仍具有纤维素的基本化学结构.NCC胶体为剪切变稀的假塑性流体,随着温度的升高,其黏度逐渐减小,并最终趋于平缓,结果表明NCC胶体具有较好的稳定性.%Nanocellulose crystal (NCC) was prepared by ultrasonic-assisted hydrolysis with strong acidic cation exchange resin. The size and morphology, crystal structure, spectrum properties and rheological behavior of nanocellulose crystal were investigated by field emission gun environment scanning electron microscopes (ESEM-FEG), field emission transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry(FT-IR) and rotor rheometer. The results indicate that the nanocellulose crystal is spherical and the size is about 25 nm~50 nm. The samples have the crystalline cellulose I structure, the crystallinity is 84.26% , and the grain is composed of 6 unit crystal cell. Moreover, the results of FT-IR show that NCC still has the basic chemical structure of cellulose. NCC is the shear thinned pseudoplastic fluid. Futhermore, as the temperature increases, its viscosity decreases, and gradually tends to flat, the results indicate that the samples enjoy nice stability.

  3. 基于阳离子交换-反相混合分离模式的液相色谱-质谱联用检测河豚毒素新方法%Determination of tetrodotoxin using a cation exchange-reverse phase liquid chromatography-mass spectrometric method

    Institute of Scientific and Technical Information of China (English)

    刘希; 陈佳; 刘勤; 郭磊; 毛军文; 谢剑炜

    2012-01-01

    Objective To establish a highly sensitive method suitable for detection of intoxicated biomedical samples with regard to tetrodotoxin ,one of the most toxic non-proteins as well as a hydrophilic small biotoxin . Methods A novel method for detection of tetrodotoxin in human blood plasma by liquid chromatography -time of flight/mass spectrometry ( LC-TOF/MS) technique was established using a cation exchange -reverse phase separation mode. The LC-MS analysis and extraction conditions were systematically optimized. Results For the tetrodotoxin standard sample , the linear calibration curve ranged from 0.1 to 50 mg/L and the limit of detection ( LOD) was 0.01 mg/L. For the tetrodotoxin exposed human plasma sample, the linear calibration curve ranged from 0.5 to 10 mg/L and the LOD was 0.25 mg/L, respectively. Conclusion Such an LC-TOF/MS established for the detection of tetrodotoxin is highly specific and sensitive , and it can be feasible for the detection of tetrodotoxin at mg/L level in puffer fish biosamples.%目的 建立一种可用于检测中毒生物医学样品中小分子生物毒素--河豚毒素的高灵敏度分析方法.方法 选用阳离子交换-反相混合色谱柱,针对河豚毒素亲水性强的特点,建立了一种新型的液相色谱-飞行时间质谱方法对人血浆中河豚毒素进行检测,优化了液相色谱-质谱条件,考察了血浆中河豚毒素的提取方法.结果 对于参考品溶液,河豚毒素的线性范围为0.1~50 mg/L,检测限为0.01 mg/L;对于染毒人血浆样品,河豚毒素的线性范围为0.5~10 mg/L,检测限为0.25 mg/L.结论 所建立的液相色谱-飞行时间质谱方法专属性强、灵敏度高,可适用于实际测定河豚鱼头样品中 mg/L水平的河豚毒素.

  4. Phosphate and ammonium sorption capacity of biochar and hydrochar from different wastes.

    Science.gov (United States)

    Takaya, C A; Fletcher, L A; Singh, S; Anyikude, K U; Ross, A B

    2016-02-01

    The potential for biochar and hydrochar to adsorb phosphate and ammonium is important for understanding the influence of these materials when added to soils, compost or other high nutrient containing environments. The influence of physicochemical properties such as mineral content, surface functionality, pH and cation exchange capacity has been investigated for a range of biochars and hydrochars produced from waste-derived biomass feedstocks. Hydrochars produced from hydrothermal carbonisation at 250 °C have been compared to low and high temperature pyrolysis chars produced at 400-450 °C and 600-650 °C respectively for oak wood, presscake from anaerobic digestate (AD), treated municipal waste and greenhouse waste. In spite of differences in char physicochemical properties and processing conditions, PO4-P and NH4-N sorption capacities ranged from about 0 to 30 mg g(-1) and 105.8-146.4 mg g(-1) respectively. Chars with high surface areas did not possess better ammonium adsorption capacities than low surface area chars, which suggests that surface area is not the most important factor influencing char ammonium adsorption capacity, while char calcium and magnesium contents may influence phosphate adsorption. Desorption experiments only released a small fraction of adsorbed ammonium or phosphate (<5 mg g(-1) and a maximum of 8.5 mg g(-1) respectively). PMID:26702555

  5. Exchange Equilibria on the Surface of Ionic Crystals

    International Nuclear Information System (INIS)

    New experimental data obtained by tracer techniques are presented and discussed. The number of exchanging cations and anions per unit area on the surface of BaSO4 and SrSO4 was measured for equivalent particles, cationic particles and anionic particles. Equivalent particles obtained by washing the precipitates thoroughly with water showed constant ratios of exchanging cations and anions per unit area of the surface. For cationic particles and anionic particles obtained by treatmeni of the precipitates with solutions containing barium ions or sulphate ions respectively, the ratio of the numbers of exchanging cations and anions was changed to higher values (cationic particles) or to lower values (anionic particles). From the values obtained the number of potential determining ions on the surface was determined. In the case of SrSO4 the numbers of exchanging cations and anions per unit area of the surface were measured as a function of temperature. They were found to decrease rapidly below 40°C in water solutions. This is explained by the immobilization of the water molecules on special points of the surface (in cracks for instance) proceeding gradually on approaching the freezing point. In agreement with this explanation the immobilization starts at lower temperatures for water-methanol mixtures. The exchange equilibria between different cations have been measured on the surface of the alkaline earth carbonates and sulphates and on the surface of the alkali tetraphenylborates. The equilibrium constants for these heterogeneous exchange reactions are discussed. In general these equilibria show the same trend as the solubilities. Barium ions, for instance, are enriched on the surface of strontium sulphate. The ratio of the solubilities, however, is no measure for these equilibria. The exchange equilibria on the surface of the alkaline earth sulphates show ''ideal'' behaviour; they are independent of the lattice parameters. (author)

  6. Mono- and polyprotic buffer systems in anion exchange chromatography of influenza virus particles.

    Science.gov (United States)

    Vajda, Judith; Weber, Dennis; Stefaniak, Sabine; Hundt, Boris; Rathfelder, Tanja; Müller, Egbert

    2016-05-27

    Different ions typically used in downstream processing of biologicals are evaluated for their potential in anion exchange chromatography of an industrially produced, pandemic influenza H1N1 virus. Capacity, selectivity and recovery are investigated based on single step elution parallel chromatography experiments. The inactivated H1N1 feedstream is produced in Madin-Darby Bovine Kidney cells. Interesting effects are found for sodium phosphate and sodium citrate. Both anions are triprotic kosmotropes. Anion exchange chromatography generally offers high scalability to satisfy sudden demands for vaccines, which may occur in case of an emerging influenza outbreak. Appropriate pH conditions for H1N1 adsorption are determined by Zeta potential measurements. The dynamic binding capacity of a salt tolerant polyamine-type resin is up to 6.4 times greater than the capacity of a grafted Q-type resin. Pseudo-affinity interactions of polyamines with the M2 protein of influenza may contribute to the obtained capacity increase. Both resins achieve greater capacity in sodium phosphate buffer compared to Tris/HCl. A recovery of 67% and DNA clearance close to 100% without DNAse treatment are achieved for the Q-type resin. Recovery of the virus from the salt tolerant resin requires the use of polyprotic acids in the elution buffer. 85% of the DNA and 60% of the proteins can be removed by the salt tolerant resin. The presence of sodium phosphate during anion exchange chromatography seems to support stability of the H1N1 particles in presence of hydrophobic cations. PMID:27130581

  7. Phosphate removal and recovery from water using nanocomposite of immobilized magnetite nanoparticles on cationic polymer.

    Science.gov (United States)

    Abo Markeb, Ahmad; Alonso, Amanda; Dorado, Antonio David; Sánchez, Antoni; Font, Xavier

    2016-08-01

    A novel nanocomposite (NC) based on magnetite nanoparticles (Fe3O4-NPs) immobilized on the surface of a cationic exchange polymer, C100, using a modification of the co-precipitation method was developed to obtain magnetic NCs for phosphate removal and recovery from water. High-resolution transmission electron microscopy-energy-dispersive spectroscopy, scanning electron microscopy , X-ray diffraction, and inductively coupled plasma optical emission spectrometry were used to characterize the NCs. Continuous adsorption process by the so-called breakthrough curves was used to determine the adsorption capacity of the Fe3O4-based NC. The adsorption capacity conditions were studied under different conditions (pH, phosphate concentration, and concentration of nanoparticles). The optimum concentration of iron in the NC for phosphate removal was 23.59 mgFe/gNC. The sorption isotherms of this material were performed at pH 5 and 7. Taking into account the real application of this novel material in real water, the experiments were performed at pH 7, achieving an adsorption capacity higher than 4.9 mgPO4-P/gNC. Moreover, Freundlich, Langmuir, and a combination of them fit the experimental data and were used for interpreting the influence of pH on the sorption and the adsorption mechanism for this novel material. Furthermore, regeneration and reusability of the NC were tested, obtaining 97.5% recovery of phosphate for the first cycle, and at least seven cycles of adsorption-desorption were carried out with more than 40% of recovery. Thus, this work described a novel magnetic nanoadsorbent with properties for phosphate recovery in wastewater. PMID:26849360

  8. Ion exchange characteristics of decontaminating formulations as suited to nuclear reactors

    International Nuclear Information System (INIS)

    Ion exchangers are employed in the chemical decontamination process for metal ion removal, regeneration of decontaminants and removal of the formulation chemicals from the coolant. Decontaminants can interact with both strong base and acid ion exchangers leading to a loss of the required chemical concentrations in the liquid phase for effectively decontaminating the radioactive deposits. In order to understand these interactions, adsorption of EDTA, HEEDTA, DTPA and NTA on strong cation exchanger was studied under dynamic conditions. Selective retention of decontaminant formulation on anion exchanger, pickup of metals by preequilibrated anion exchanger and the effect of temperature on the cation exchanger were studied. (author)

  9. Preparation and characterization of cationic and amphoteric mannans from Candida albicans.

    Science.gov (United States)

    Čížová, Alžbeta; Neščáková, Zuzana; Malovíková, Anna; Bystrický, Slavomír

    2016-09-20

    Cationic and amphoteric mannans from Candida albicans were prepared by chemical modification with (3-chloro-2-hydroxypropyl)trimethylammonium chloride (CHPTAC) and sodium chloroacetate under aqueous alkaline conditions. The optimal reaction conditions for mannan cationization were found to be 6h, 60°C, and NaOH/CHPTAC ratio of 1.0. Adjusting the molar ratio of cationization agent to anhydromannose unit, cationic and amphoteric mannans with degree of substitution ranging from 0.07 to 0.57 were obtained. Their structure was confirmed by elemental analysis as well as FTIR and NMR spectroscopies. Moderate decrease of molecular weight of both cationic and amphoteric mannans was recorded by size exclusion chromatography. With increasing level of modification, reduction of the antibody-binding capacity was observed by enzyme-linked immunosorbent assay. PMID:27261724

  10. Oxygen Isotope Fractionation Effects in Soil Water via Cations Adsorbed to High-CEC Clays

    Science.gov (United States)

    Oerter, E.; Finstad, K.; Schaefer, J.; Goldsmith, G. R.; Dawson, T. E.; Amundson, R.

    2012-12-01

    In isotope-based approaches to hydrology, soil and sediment are implicitly considered to be an inert matrix in which water resides or moves. Yet, this assumption is inconsistent with the fact that soils contain a wide range of solutes, and highly variable concentrations of chemically reactive clay particles, all of which may react with bulk water and create pools of energetically differing water with varying isotope compositions. The empirical basis of this hypothesis is the work of Sofer and Gat (1972, EPSL, 15(3)), who showed that the formation of hydration spheres around cations in aqueous solutions fractionate oxygen isotopes of water in ways that appear to be dependent on the cation's ionic potential and concentration. Because soil solutions commonly have high solid to fluid ratios, the potential for solids to create substantial pools of low free energy water, with corresponding isotope fractionation of the free and low energy waters, may be a common process. The potential for this to create measurable isotopic effects would be most evident in soils with high Cation Exchange Capacity (CEC). In order to test this hypothesis, montmorillonite (CEC ≈ 100 meq/100g), kaolinite (CEC≈10) and quartz (CEC≈0) mineral powders were saturated with 3M MgCl2 and KCl solutions (separately), rinsed with methanol and dried to saturate all available CEC sites with either Mg or K cations. Triplicate sets of monominerallic-deionized water mixtures were created at 5, 25, 50, 75 and 95% gravimetric water content. Each set of samples was then subjected to one of three water extraction techniques designed to access specific "pools" of soil water: (1) direct equilibration with CO2 to sample the soil's "free water", i.e. water not adsorbed to cations via hydration spheres; (2) centrifugation to simulate permanent wilting point conditions, thereby yielding most micro-pore, macro-pore, and free water; and (3) cryogenic vacuum distillation to recover all the soil water (free, pore and

  11. Research progress in cation-π interactions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cation-π interaction is a potent intermolecular interaction between a cation and an aromatic system,which has been viewed as a new kind of binding force,as being compared with the classical interactions(e.g. hydrogen bonding,electrostatic and hydrophobic interactions). Cation-π interactions have been observed in a wide range of biological contexts. In this paper,we present an overview of the typical cation-π interactions in biological systems,the experimental and theoretical investigations on cation-π interactions,as well as the research results on cation-π interactions in our group.

  12. Liquid-solid extraction of metallic cations by cationic amphiphiles

    International Nuclear Information System (INIS)

    In the field of selective metal ion separation, liquid-liquid extraction is usually conducted through an emulsion mixing of hydrophobic complexants dispersed in an organic phase and acidic water containing the ionic species. Recently, it has been shown that amphiphilic complexants could influence strongly extraction efficiency by enhancing the interfacial interaction between the metal ion in the aqueous and the complexant in the organic phase. Moreover, these amphiphiles can also substitute the organic phase if an appropriate aliphatic chain is chosen. The dispersion of such amphiphilic complexants in an aqueous solution of salt mixtures is not only attractive for studying specific interactions but also to better the understanding of complex formation in aqueous solution of multivalent metal ions, such as lanthanides and actinides. This understanding is of potential interest for a broad range of industries including purification of rare earth metals and pollute treatment e.g. of fission byproducts. This principle can also be applied to liquid-solid extraction, where the final state of the separation is a solid phase containing the selectively extracted ions. Indeed, a novel solid-liquid extraction method exploits the selective precipitation of metal ions from an aqueous salt mixture using a cationic surfactant, below its Krafft point (temperature below which the long aliphatic chains of surfactant crystallize). This technique has been proven to be highly efficient for the separation of actinides and heavy metal using long chain ammonium or pyridinium amphiphiles. The most important point in this process is the recognition of cationic metal ions by cationic surfactants. By computing the free energy of the polar head group per micelle as a function of the different counter-anions, we have demonstrated for the first time that different interactions exist between the micellar surface and the ions. These interactions depend on the nature of the cation but also on

  13. Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations

    Directory of Open Access Journals (Sweden)

    María del Valle Martínez de Yuso

    2014-04-01

    Full Text Available Surface and bulk changes in a Nafion membrane as a result of IL-cation doping (1-butyl-3-methylimidazolium tetrafluoroborate or BMIM+BF4 and phenyltrimethylammonium chloride or TMPA+Cl− were studied by X-ray photoelectron spectroscopy (XPS, contact angle, differential scanning calorimetry (DSC and impedance spectroscopy (IS measurements performed with dry samples after 24 h in contact with the IL-cations BMIM+ and TMPA+. IL-cations were selected due to their similar molecular weight and molar volume but different shape, which could facilitate/obstruct the cation incorporation in the Nafion membrane structure by proton/cation exchange mechanism. The surface coverage of the Nafion membrane by the IL-cations was confirmed by XPS analysis and contact angle, while the results obtained by the other two techniques (DSC and IS seem to indicate differences in thermal and electrical behaviour depending on the doping-cation, being less resistive the Nafion/BMIM+ membrane. For that reason, determination of the ion transport number was obtained for this membrane by measuring the membrane or concentration potential with the samples in contact with HCl solutions at different concentrations. The comparison of these results with those obtained for the original Nafion membrane provides information on the effect of IL-cation BMIM+ on the transport of H+ across wet Nafion/BMIM+ doped membranes.

  14. Bifunctional Crosslinking Agents Enhance Anion Exchange Membrane Efficacy for Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Wang, Wenpin; Xu, Min; Wang, Shubo; Xie, Xiaofeng; Lv, Yafei; Ramani, Vijay K

    2014-06-01

    A series of cross-linked fluorinated poly (aryl ether oxadiazole) membranes (FPAEOM) derivatized with imidazolium groups were prepared. Poly (N-vinylimidazole) (PVI) was used as the bifunctional cross-linking agent to: a) lower vanadium permeability, b) enhance dimensional stability, and c) concomitantly provide added ion exchange capacity in the resultant anion exchange membranes. At a molar ratio of PVI to FPAEOM of 1.5, the resultant membrane (FPAEOM-1.5 PVI) had an ion exchange capacity of 2.2 meq g-1, a vanadium permeability of 6.8×10-7 cm2 min-1, a water uptake of 68 wt.%, and an ionic conductivity of 22.0 mS cm-1, all at 25°C. Single cells prepared with the FPAEOM-1.5 PVI membrane exhibited a higher coulombic efficiency (> 92%) and energy efficiency (> 86%) after 40 test cycles in vanadium redox flow battery. The imidazolium cation showed high chemical stability in highly acidic and oxidizing vanadium solution as opposed to poor stability in alkaline solutions. Based on our DFT studies, this was attributed to the lower HOMO energy (-7.265 eV) of the HSO4- ion (compared to the OH- ion; -5.496 eV) and the larger HOMO-LUMO energy gap (6.394 eV) of dimethylimidazolium bisulfate ([DMIM] [HSO4]) as compared to [DMIM] [OH] (5.387 eV). PMID:24884171

  15. THERMODYNAMICS OF ION-EXCHANGED NATURAL CLINOPTILOLITE

    Science.gov (United States)

    Natural clinoptilolite from Castle Creek, Idaho, and its cation-exchanged variants (Na-Cpt, NaK-Cpt, K-Cpt, and Ca-Cpt) were studied by high-temperature calorimetry. The hydration enthalpy for all clinoptilolites is about -30 kJ/mol H2O (liquid water reference state) at 25 C. T...

  16. Fixation by ion exchange of toxic materials in a glass matrix

    International Nuclear Information System (INIS)

    A process is reported for reacting a porous silicate or borosilicate glass or silica gel with alkali metal cations, Group lb cations and/or ammonium cations bonded to the silicon through divalent oxygen linkages on the internal surfaces of the pores. Ion exchange of the cations with toxic or radioactive cations was possible resulting in a distribution of internal silicon-bonded toxic cation oxide groups within the pores of the glass or silica gel. The ion exchange reaction may be done successfully with acidic, neutral or alkaline pH solutions. The aim of the immobilization is for permanent storage of hazardous materials such as Hg2+, Hg+, Cd2+, Tl+, Pb2+ and radioactive cations

  17. Study of kinetics, equilibrium and isotope exchange in ion exchange systems Pt. 5

    International Nuclear Information System (INIS)

    The kinetics of Na+ - UO22+ and Mg2+ - UO22+ ion exchange on strongly acidic cation exchangers in a batch stirred reactor was studied. The exchangers Ostion KS (containing DVB in the range of 1.5-12%) and Amberlite IR 120 for experimental work were used; the concentration of the aqueous nitrate solution was always 0.2 molx1-1. The Nernst-Planck equation was applied for description of ion diffusion in the particle. The diffusion coefficients of UO22+ ions in the exchangers and their dependence on the content of DVB were obtained by evaluating the experimental data. (author)

  18. Study of kinetics, equilibrium and isotope exchange in ion exchange systems Pt. 4

    International Nuclear Information System (INIS)

    The kinetics of ion exchange in the Nasup(+)-Mgsup(2+)-strongly acidic cation exchanger system in a batch stirred reactor was studied. The samples of exchangers OSTION KS (containing DVB in the range of 1.5 - 12%) and AMBERLITE IR 120 for experimental work were used; the concentration of the aqueous nitrate solution was always 0.2M. The Nernst-Planck equation for description of diffusion of ions in a particle was used. The values of diffusion coefficients of magnesium ions in the exchangers and their dependence on the content of DVB were obtained by evaluating the experimental data and using the self-diffusion coefficients of sodium. (author)

  19. Polyelectrolyte Condensation Induced by Linear Cations

    OpenAIRE

    Guáqueta, Camilo; Luijten, Erik

    2007-01-01

    We examine the role of the condensing agent in the formation of polyelectrolyte bundles, via grand-canonical Monte Carlo simulations. Following recent experiments we use linear, rigid divalent cations of various lengths to induce condensation. Our results clarify and explain the experimental results for short cations. For longer cations we observe novel condensation behavior owing to alignment of the cations. We also study the role of the polyelectrolyte surface charge density, and find a non...

  20. Natural zeolite reactivity towards ozone: The role of compensating cations

    International Nuclear Information System (INIS)

    Highlights: ► Chemical and thermal treatment enhances catalytic activity of natural zeolite. ► Modified natural zeolite exhibits high stability after thermal treatment. ► Reducing the compensating cation content leads to an increase on ozone abatement. ► Surface active atomic oxygen was detected using the DRIFT technique. ► 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−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 (NH3-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.

  1. Natural zeolite reactivity towards ozone: The role of compensating cations

    Energy Technology Data Exchange (ETDEWEB)

    Valdes, Hector, E-mail: hvaldes@ucsc.cl [Laboratorio de Tecnologias Limpias (F. Ingenieria), Universidad Catolica de la Santisima Concepcion, Alonso de Ribera 2850, Concepcion (Chile); Alejandro, Serguei; Zaror, Claudio A. [Departamento de Ingenieria Quimica (F. Ingenieria), Universidad de Concepcion, Concepcion (Chile)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Chemical and thermal treatment enhances catalytic activity of natural zeolite. Black-Right-Pointing-Pointer Modified natural zeolite exhibits high stability after thermal treatment. Black-Right-Pointing-Pointer Reducing the compensating cation content leads to an increase on ozone abatement. Black-Right-Pointing-Pointer Surface active atomic oxygen was detected using the DRIFT technique. Black-Right-Pointing-Pointer The highest reactivity toward ozone was performed by NH4Z3 zeolite sample. - Abstract: Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L{sup -1}). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77 K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH{sub 3}-TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal.

  2. Cationic electrodepositable coating composition comprising lignin

    Science.gov (United States)

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter

    2013-07-30

    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.

  3. Electrically switched ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Lilga, M.A. [Pacific Northwest National Lab., Richland, WA (United States); Schwartz, D.T.; Genders, D.

    1997-10-01

    A variety of waste types containing radioactive {sup 137}Cs are found throughout the DOE complex. These waste types include water in reactor cooling basins, radioactive high-level waste (HLW) in underground storage tanks, and groundwater. Safety and regulatory requirements and economics require the removal of radiocesium before these wastes can be permanently disposed of. Electrically Switched Ion Exchange (ESIX) is an approach for radioactive cesium separation that combines IX and electrochemistry to provide a selective, reversible, and economic separation method that also produces little or no secondary waste. In the ESIX process, an electroactive IX film is deposited electrochemically onto a high-surface area electrode, and ion uptake and elution are controlled directly by modulating the potential of the film. For cesium, the electroactive films under investigation are ferrocyanides, which are well known to have high selectivities for cesium in concentrated sodium solutions. When a cathode potential is applied to the film, Fe{sup +3} is reduced to the Fe{sup +2} state, and a cation must be intercalated into the film to maintain charge neutrality (i.e., Cs{sup +} is loaded). Conversely, if an anodic potential is applied, a cation must be released from the film (i.e., Cs{sup +} is unloaded). Therefore, to load the film with cesium, the film is simply reduced; to unload cesium, the film is oxidized.

  4. Calorimetric study of cationic photopolymerization

    International Nuclear Information System (INIS)

    The photopolymerization of penta-erythritol tetra-glycidyl ether (initiator Degacure KI-85) was studied by a du Pont 910 type DSC. From our experimental results the following conclusions can be drawn: (1) During the cationic polymerization reaction the lifetime of the initiating centers are long compared to the lifetime of free radicals in case of radical polymerization. (2) The rate of deactivation of the initiating centers increases with increasing temperature. (author)

  5. Chromium(VI) adsorption from aqueous solution onto Moroccan Al-pillared and cationic surfactant stevensite.

    Science.gov (United States)

    Benhammou, Abdelaziz; Yaacoubi, Abdelrani; Nibou, Lahbib; Tanouti, Boumediane

    2007-02-01

    Batch adsorption of the chromium(VI) onto Moroccan stevensite pillared by Keggin aluminium hydroxypolycation (Al-stevensite) and cationic surfactant cetyltrimethylammoniumbromide (CTA-stevensite) was investigated. The results showed that the CTA-stevensite has a higher affinity than that of Al-stevensite for chromium(VI) adsorption. The adsorption capacities for natural stevensite, Al-stevensite and CTA-stevensite calculated according to the Dubinin-Kaganer-Radushkevich isotherm (DKR) are 13.7, 75.4 and 195.6mmolkg(-1), respectively. The study of the pH effect showed that the optimal range corresponding to the Cr(VI) maximum adsorption on Al-stevensite is pH 3.5-6 and that on CTA-stevensite is pH 2-6. The adsorption rates evaluated according to the pseudo-second-order model are 7.2, 207.2 and 178.5mmolkg(-1)min(-1) for the natural stevensite, Al-stevensite and CTA-stevensite, respectively. The low values of the adsorption energy calculated by (DKR) suggest that anion exchange is the main mechanism that governs the chromate adsorption. PMID:16876943

  6. Enhanced Mixed Electronic-Ionic Conductors through Cation Ordering

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Allan J. [Univ. of Houston, TX (United States); Morgan, Dane [Univ. of Wisconsin, Madison, WI (United States); Grey, Clare [Stony Brook Univ., NY (United States)

    2014-08-31

    The performance of many energy conversion and storage devices depend on the properties of mixed ionic-electronic conducting (miec) materials. Mixed or ambipolar conductors simultaneously transport ions and electrons and provide the critical interface between chemical and electrical energy in devices such as fuel cells, ion transport membranes, and batteries. Enhancements in storage capacity, reversibility, power density and device lifetime all require new materials and a better understanding of the fundamentals of ambipolar conductivity and surface reactivity.The high temperature properties of the ordered perovksites AA’B2O5+x, where A = rare earth ion, Y and B = Ba, Sr were studied. The work was motivated by the high oxygen transport and surface exchange rates observed for members of this class of mixed ionic and electronic conductors. A combined experimental and computational approach, including structural, electrochemical, and transport characterization and modeling was used. The approach attacks the problem simultaneously at global (e.g., neutron diffraction and impedance spectroscopy), local (e.g., pair distribution function, nuclear magnetic resonance) and molecular (ab initio thermokinetic modeling) length scales. The objectives of the work were to understand how the cation and associated anion order lead to exceptional ionic and electronic transport properties and surface reactivity in AA’B2O5+x perovskites. A variety of compounds were studied by X-ray and neutron diffraction, measurements of thermodynamics and transport and theoretically. These included PrBaCo2O5+x and NdBaCo2O5+x, PrBaCo2-xFexO6- δ (x = 0, 0.5, 1.0, 1.5 and 2) and LnBaCoFeO6- δ (Ln = La, Pr, Nd, Sm, Eu and Gd), Sr3YCo4O10.5, YBaMn2O5+x. A0.5A’0.5BO3 (where A=Y, Sc, La, Ce, Pr, Nd, Pm, Sm; A’= Sr

  7. Comparison of Phosphoproteomic Separation Strategies Based on Strong Cation Exchange Chromatography-Isoelectric Focusing Techniques%基于强阳离子交换色谱与等电聚焦的磷酸化蛋白质组学分离策略比较

    Institute of Scientific and Technical Information of China (English)

    隋少卉; 董俊军; 王京兰; 蔡耘; 钱小红

    2012-01-01

    Efficient pre-purification steps for the enrichment of phosphorylated proteins or phos-phopeptides are necessary for better detection of phosphorylation sites in phosphoproteomic analysis. Currently, the most common first-dimensional separation technique used is strong cation exchange (SCX). A potential alternative to SCX-based separation is to use isoelectric focusing (IEF) as a first-dimensional separation technique, which has been demonstrated recently. In this study, we present a direct comparison between SCX and IEF based on IPG strips (IPG-IEF) for the phosphoproteomic separation. The comparison experiments discussed in this study utilized standard phosphoproteins and a real sample of HepG2 cell. Then the comparison of 18O labeling phosphopeptides' stability under immobilized pH gradient gel (IPG)-IEF with under SCX was made. Fractions from both technique (SCX and IPG-IEF) were analyzed using the High Mass Accuracy LTQ-FTICR-MS/MS. The results demonstrate that SCX-LTQ-FT and IPG-IEF-LTQ-FT are useful in the phosphopeptides enrichment analysis on a large scale. And SCX-LTQ-FT is relative superior to IPG-IEF-LTQ-FT, whereas the 18 O labeling phosphopeptides'stability under SCX-LTQ-FT is relatively poor with that under IPG-IEF-LTQ-FT.%比较分析了强阳离子交换(SCX)与等电聚焦(IPG-IEF)技术在磷酸化蛋白质组学中的应用.采用3种标准磷酸化蛋白对SCX与IPG-IEF两种技术对磷酸化肽段富集的有效性进行考察.以HepG2细胞为复杂样本,考察SCX与IPG-IEF在实际样本中的应用情况.对SCX与IPG-IEF技术在18O标记的磷酸化蛋白质组定量研究中的应用情况进行考察.蛋白鉴定采用高准确度、高灵敏度、高分辨率的LTQ-FTICR-MS/MS质谱仪.实验表明:SCX和IPG- IEF在大规模磷酸化肽段分离过程中均有效;在复杂样本中,SCX技术的分离效果优于IPG- IEF; IPG- IEF的重复性好于SCX;在磷酸化蛋白质组定量分析结果表明,IPG-IEF技术的稳定性优

  8. 弱酸型聚合物微球固相萃取填料的制备及水中杀虫剂的测定%Preparation of weak acid cation exchange polymer microspheres solid-phase extraction packing and determination of pesticides in river water

    Institute of Scientific and Technical Information of China (English)

    申书昌; 徐雅雯; 马柏凤

    2015-01-01

    The polymer microspheres with lipotropy and weak cation exchange performance were prepared through suspension poly-merization method using styrene and divinyl benzene and methyl acrylate as monomers,PVA as dispersant,benzoyl peroxide as the initiator. The structure and morphology of microspheres were examined by infrared spectrum and scanning electron micro-scope. While observing the structure and morphology of the filler. The composite microspheres were used as solid-phase extraction ( SPE) sorbents for selective extraction nitroclofene,bithionol,praziquantel and albendazole in the river water. Acetonitrile was used as eluent,and the eluate was determined by high performance liquid chromatography. The effects of the sample flow rate and pH, volume and flow rate of eluent on adsorption ratios were investigated,the best solid phase extraction conditions were obtained. The best HPLC condition was chosen. The results show that SiO2/PS composite microspheres have a uniform monodispersity in particle size. The SPE sorbents have good adsorption performance to nitroclofene,bithionol,praziquantel and albendazole in water,and the method of SPE-HPLC for determining the four pesticides has good reproducibility, the detection limits for nitroclofene, bithionol, praziquantel and albendazole were 0. 26μg·L-1 ,0. 31μg·L-1 ,0. 42μg·L-1 and 0. 63μg·L-1 respectively.%本文制备了聚合物基质弱酸型阳离子交换固相萃取填料,以甲基丙烯酸和苯乙烯为原料,二乙烯基苯为交联剂,聚乙烯醇为分散剂,过氧化苯甲酰为引发剂,采用悬浮聚合法制备了具有亲脂和弱阳离子交换性能的球形固相萃取填料,并对其结构和形貌进行了表征。以该聚合物微球作为填料制备固相萃取小柱,萃取水中联硝氯酚、硫双二氯酚、吡喹酮和丙硫苯咪唑4种杀虫剂,乙腈为洗脱剂,洗脱液采用液相色谱分析。分别考察了样品的pH值和流速、洗脱剂的体积和流

  9. The structure of actinide ions exchanged into native and modified zeolites and clays

    International Nuclear Information System (INIS)

    X-ray absorption spectroscopy (XAS) has been used to investigate the structure and valence of thorium (Th4+) and uranyl (UO22+) cations exchanged into two classes of microporous aluminosilicate minerals: zeolites and smectite clays. XAS is also employed to examine the fate of the exchanged cations after modification of the mineral surface using self-assembled organic films and/or exposure to hydrothermal conditions. These treatments serve as models for the forces that ultimately determine the chemical fate of the actinide cations in the environment. The speciation of the cations depends on the pore size of the aluminosilicate, which is fixed for the zeolites and variable for the smectites

  10. Plasmalemmal and mitochondrial Na(+) -Ca(2+) exchange in neuroglia.

    Science.gov (United States)

    Parpura, Vladimir; Sekler, Israel; Fern, Robert

    2016-10-01

    In the absence of the electrical signaling for which neurons are so highly specialized, GLIA rely on the slow propagation of ionic signals to mediate network events such as Ca(2+) and Na(+) waves. Glia differ from neurons in another important way, they are replete with a high density of ionic-transport proteins that are essential for them to fulfil their basic functions as guardians of the intra and extra-cellular milieux. Both the signaling and the homeostatic properties of glial cells are therefore particularly dependent upon the regulation of the two principle physiological metal cations, Ca(2+) and Na(+) . For both ions, glia express high-affinity/low capacity ATP-fuelled pumps that can rapidly move small numbers of ions against an electro-chemical gradient. For both Ca(2+) and Na(+) regulation, a single transporter family, the Na(+) -Ca(2+) exchanger (NCX), is used to maintain cellular ion homeostasis over the longer term and under conditions of prolonged or acute ionic dysregulation in astrocytes, oligodendroglia and microglia. Our understanding of glial NCX, both plasmalemmal and mitochondrial, is undergoing the kind of transformation that our understanding of glial cells, in general, has undergone in recent decades. These exchange proteins are becoming increasingly recognized for their essential roles in intracellular homeostasis while their signaling functions are starting to come to light. This review summarizes these key aspects and highlights the many areas where work has yet to begin in this rapidly evolving field. GLIA 2016;64:1646-1654. PMID:27143128

  11. The Effects of Sulfonated Poly(ether ether ketone Ion Exchange Preparation Conditions on Membrane Properties

    Directory of Open Access Journals (Sweden)

    Rebecca S. L. Yee

    2013-08-01

    Full Text Available A low cost cation exchange membrane to be used in a specific bioelectrochemical system has been developed using poly(ether ether ketone (PEEK. This material is presented as an alternative to current commercial ion exchange membranes that have been primarily designed for fuel cell applications. To increase the hydrophilicity and ion transport of the PEEK material, charged groups are introduced through sulfonation. The effect of sulfonation and casting conditions on membrane performance has been systematically determined by producing a series of membranes synthesized over an array of reaction and casting conditions. Optimal reaction and casting conditions for producing SPEEK ion exchange membranes with appropriate performance characteristics have been established by this uniquely systematic experimental series. Membrane materials were characterized by ion exchange capacity, water uptake, swelling, potential difference and NMR analysis. Testing this extensive membranes series established that the most appropriate sulfonation conditions were 60 °C for 6 h. For mechanical stability and ease of handling, SPEEK membranes cast from solvent casting concentrations of 15%–25% with a resulting thickness of 30–50 µm were also found to be most suitable from the series of tested casting conditions. Drying conditions did not have any apparent impact on the measured parameters in this study. The conductivity of SPEEK membranes was found to be in the range of 10−3 S cm−1, which is suitable for use as a low cost membrane in the intended bioelectrochemical systems.

  12. Removal of cationic dye from water by activated pine cones

    Directory of Open Access Journals (Sweden)

    Momčilović Milan Z.

    2012-01-01

    Full Text Available Adsorption of a cationic phenothyazine dye methylene blueonto activated carbon prepared from pine cones was investigated with the variation in parameters of contact time, dye concentration and pH. The kinetic data were found to follow the pseudo-second-order kinetic modelclosely. The equilibrium data were best represented by the Langmuir isotherm with maximum adsorption capacity of 233.1 mg g-1. Adsorption was favored by using a higher solution pH. Textural analysis by nitrogen adsorption was used to determine specific surface area and pore structure of the obtained carbon. Boehm titrations revealed that carboxylic groups are present in the highest degree on the carbon surface. The results indicate that the presented method for activation of pine cones could yield activated carbon with significant porosity, developed surface reactivity and considerable adsorption affinity toward cationic dye methylene blue.

  13. Influence of soil properties on heavy metal sequestration by biochar amendment: 1. Copper sorption isotherms and the release of cations.

    Science.gov (United States)

    Uchimiya, Minori; Klasson, K Thomas; Wartelle, Lynda H; Lima, Isabel M

    2011-03-01

    The amendment of carbonaceous materials such as biochars and activated carbons is a promising in situ remediation strategy for both organic and inorganic contaminants in soils and sediments. Mechanistic understandings in sorption of heavy metals on amended soil are necessary for appropriate selection and application of carbonaceous materials for heavy metal sequestration in specific soil types. In this study, copper sorption isotherms were obtained for soils having distinct characteristics: clay-rich, alkaline San Joaquin soil with significant heavy metal sorption capacity, and eroded, acidic Norfolk sandy loam soil having low capacity to retain copper. The amendment of acidic pecan shell-derived activated carbon and basic broiler litter biochar lead to a greater enhancement of copper sorption in Norfolk soil than in San Joaquin soil. In Norfolk soil, the amendment of acidic activated carbon enhanced copper sorption primarily via cation exchange mechanism, i.e., release of proton, calcium, and aluminum, while acid dissolution of aluminum cannot be ruled out. For San Joaquin soil, enhanced copper retention by biochar amendment likely resulted from the following additional mechanisms: electrostatic interactions between copper and negatively charged soil and biochar surfaces, sorption on mineral (ash) components, complexation of copper by surface functional groups and delocalized π electrons of carbonaceous materials, and precipitation. Influence of biochar on the release of additional elements (e.g., Al, Ca) must be carefully considered when used as a soil amendment to sequester heavy metals. PMID:21147495

  14. Biochar soil amendment for waste-stream diversion, nutrient holding capacity, and carbon sequestration in two contrasting soils

    Science.gov (United States)

    Deem, L. M.; Crow, S. E.; Deenik, J. L.; Penton, C. R.; Yanagida, J.

    2013-12-01

    Biochar is organic matter that has been pyrolized under low oxygen conditions for use as a soil amendment. Currently biochar is viewed as a way to improve soil quality (e.g., increased nutrient and water holding capacity) and increase in soil carbon (C) sequestration. The use of biochar in soil is not new, yet little is known about the underlying mechanisms that control the interactions between biochar and soil following amendment. In the past, the effects of biochar addition on crop yields, soil properties and greenhouse gas (GHG) fluxes in both in-situ and controlled experiments have produced inconsistent results. These discrepancies may be uncovered in part by chemical and physical characterization of the biochar prior to amendment and identification of soil- and biochar-specific interactions. Furthermore, a more holistic consideration of the system may demonstrate the virtues of biochar amendment beyond the typical considerations of yield and gas flux. We expect that as the differences between the physical and chemical properties of the biochar and the soil increase, the impact on the soil quality metrics will also increase. For this study, we used a waste product (i.e., anaerobic digester sludge) biochar with 81.5% C, pH of 10.44, pH-independent charge for anion exchange capacity (AEC) and a pH-dependent charge for cation exchange capacity (CEC), 4.14% moisture content and 25.75 cmol¬c /kg exchangeable base cations. This biochar was incorporated into both a low and a high fertility Hawaiian field soil to quantitate biochar effects on crop yield, soil pH, CEC, AEC, hot and cold water extractable C and nitrogen, bulk density, phosphorus, soil microbial ecology, and GHG flux in varying soil conditions. Compared to the higher fertility soil, we hypothesized that the low fertility soil would demonstrate a greater increase in soil quality, including higher pH, CEC and water holding capacity. Two crop management practices were included with each soil: traditional

  15. Incorporation of Monovalent Cations in Sulfate Green Rust

    DEFF Research Database (Denmark)

    Christiansen, B. C.; Dideriksen, K.; Katz, A.;

    2014-01-01

    Green rust is a naturally occurring layered mixed-valent ferrous-ferric hydroxide, which can react with a range of redox-active compounds. Sulfate-bearing green rust is generally thought to have interlayers composed of sulfate and water. Here, we provide evidence that the interlayers also contain...... 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...

  16. Cationic polycarbonate-grafted superparamagnetic nanoparticles with synergistic dual-modality antimicrobial activity.

    Science.gov (United States)

    Pu, Lu; Xu, Jinbao; Sun, Yimin; Fang, Zheng; Chan-Park, Mary B; Duan, Hongwei

    2016-05-26

    We report a new class of antimicrobial nanomaterials with biodegradable cationic polycarbonates grafted on superparamagnetic nanoparticles. Our results have shown that end-functionalized cationic polycarbonates, synthesized by organocatalytic ring opening polymerization, can be grafted onto superparamagnetic MnFe2O4 nanoparticles via ligand exchange. In comparison with the individual building blocks, the core-shell hybrid nanoparticles led to improved antimicrobial activities in two ways: first, the cationic polycarbonates in a brush form afforded a greater charge density than that of free polymer chains, resulting in stronger interactions with bacterial surfaces. Second, the structural integration of the "soft" polycarbonate shell and the "hard" superparamagnetic core in the hybrid nanoparticles brings about a synergistic action of membrane disruption by the cationic shell and magnetic hyperthermia by the nanoparticle core. The combination of two physical killing mechanisms holds great promise in fighting against a broad spectrum of bacterial pathogens. PMID:26906640

  17. Ion exchange reactions in amorphous and crystalline aluminium silicates from solution of cerium salts

    International Nuclear Information System (INIS)

    Reactions of ion-exchange of Na+ by Ce3+ and NH4+ on the zeolite containing catalyst, amorphous silica alumina and zeolite Y have been studied. The cerium cations are shown to be exchanged by the Na+ cations with more selectivity than the anmonia cations. In the case of the zeolite containing catalyst and amorphous silica alumina the region of the staggered ion-exchange from the mixture of the solutions of cerium and ammonium sulphates was been detected. This is explained by the formation fo cerium complexes with the sulphate ions

  18. Synthesis of polycationic bentonite-ionene complexes and their benzene adsorption capacity

    Directory of Open Access Journals (Sweden)

    Valquíria Campos

    2015-04-01

    Full Text Available The purpose of this work was to structurally modify clays in order to incorporate water-insoluble molecules, such as petroleum hydrocarbons. The potential for ion exchange of quaternary ammonium salts was studied, which revealed their ability to interact with anions on the cationic surface, for environmental applications of the material. Ionenes, also known as polycations, have many potential uses in environmental applications. In this work, cationic aliphatic ammonium polyionenes, specifically 3,6-ionene and 3,6-dodecylionene, were prepared for incorporation into clay to form bentonite-ionene complexes. The intercalation of bentonite with ionene polymers resulted in an increase in the basal spacing of 3,6-dodecylionene from 1.5-3.5 nm. The higher d001 spacing of 3,6-dodecylionene samples than that of 3,6-ionene samples may be attributed to their longer tail length. The behavior of the TG/DTG curves and the activation energy values suggest that 3,6-dodecylionene (E = 174.85 kJ mol–1 is thermally more stable than 3,6 ionene (E = 115.52 kJ mol–1 complexes. The adsorption of benzene by 3,6-ionene and 3,6-dodecylionene was also investigated. The increase in benzene concentrations resulted in increased benzene adsorption by the sorbents tested in this work. The sorption capacity of benzene on ionene-modified bentonite was in the order of 3,6-dodecylionene > 3,6-ionene.

  19. Cation coordination in oxychloride glasses

    Science.gov (United States)

    Johnson, J. A.; Holland, D.; Bland, J.; Johnson, C. E.; Thomas, M. F.

    2003-02-01

    Glasses containing mixtures of cations and anions of nominal compositions [Sb2O3]x - [ZnCl2]1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Mössbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb)2(OZn)] and [Zn(ClZn)2(OSb)2].

  20. Cation coordination in oxychloride glasses

    International Nuclear Information System (INIS)

    Glasses containing mixtures of cations and anions of nominal compositions [Sb2O3]x - [ZnCl2]1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Moessbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb)2(OZn)] and [Zn(ClZn)2(OSb)2