Ion exchange of Cs ion in acid solution with potassium cobalt hexacyanoferrate

Potassium cobalt hexacyanoferrate (KCoFC) was synthesized for removal of Cs ions in acid waste solution. The synthesized KCoFC. was stable in nitric acid solution of pH= 1 and showed high selectivity for Cs ion over Sr and Na ions. The K_d,cs for 0.01 N Cs ion solution at pH=2 was about 3.6x 10³ mL/g in the presence of the same concentrations of Sr and Na ions, respectively. In the binary ion exchange system, both the Dubinin-Polanyi model and Langmuir model fit the experimental data, although the Dubinin-Polanyi model fit more correctly than the Langmuir model. However, in the multi-component system, only the modified Dubinin-Polanyi model, which is a semiempirical equation, fit the experimental data accurately. The ion exchange capacity of KCoFC. for Cs ion obtained by the Dubinin-Polanyi equation was 1.72 meq/g.     

Preparation of PAN-zeolite 4A composite ion exchanger and its uptake behavior for Sr and Cs ions in acid solution

A PAN-4A composite ion exchanger containing about 80% 4A powder was prepared to remove strontium and cesium ions from acidic solution. The SEM image of the fracture of composite bead showed that zeolite 4A powder was dispersed homogenously and the pores were well formed. The mean pore size of composite bead was 0.14 μm and its porosity was about 74%, which is much higher in comparison with the existing inorganic adsorbent beads. The acid and radiation stability tests showed that PAN-4A was stable against acid solution higher than pH 2 and radiation dose less than 1.89×10⁸ rad, respectively. Ion exchange tests showed that the PAN-4A was selective for Sr ion. The distribution coefficients of PAN-4A for Sr and Cs ions at pH 2 were 2×10⁴ mL/g and 280 mL/g, respectively. The ion exchange capacities (q_s) of PAN-4A for Sr and Cs ions at pH 2, which are modeled by Dubinin-Polanyi equation, were 3.92 meq/g and 2.47 meq/g, respectively.     

Ion Exchange of Selected Group II Metals and Lead by Crystalline Silicotitanate and Competition for Cs Exchange Sites

ABSTRACT

A series of batch contact tests were conducted to evaluate the exchange behavior of Ba, Ca, Pb, and Sr onto crystalline silicotitanate (CST) in support of an expedited Cs removal and pretreatment system at the Hanford site. Binary Na/M²⁺ and ternary Na/Cs/M²⁺ isotherms were generated to understand selectivity, capacity, and competitive impact of each analyte on Cs uptake from a simple 1 M NaOH/4.6 M NaNO₃ simulant. Analyte loading from a 0.1 M NaOH/5.5 M NaNO₃ simulant was assessed to determine the effect of hydroxide concentration on binary Na/M²⁺ isotherms. Results from binary and ternary isotherms indicated that Group II metals Ca, Sr, and Ba (and Pb) do not impact CST performance toward Cs removal at concentrations expected in Hanford tank-waste supernate.     

Ripple coarsening on ion beam-eroded surfaces

The temporal evolution of ripple pattern on Ge, Si, Al₂O₃, and SiO₂ by low-energy ion beam erosion with Xe ⁺ ions is studied. The experiments focus on the ripple dynamics in a fluence range from 1.1 × 10¹⁷ cm^-2 to 1.3 × 10¹⁹ cm^-2 at ion incidence angles of 65° and 75° and ion energies of 600 and 1,200 eV. At low fluences a short-wavelength ripple structure emerges on the surface that is superimposed and later on dominated by long wavelength structures for increasing fluences. The coarsening of short wavelength ripples depends on the material system and angle of incidence. These observations are associated with the influence of reflected primary ions and gradient-dependent sputtering. The investigations reveal that coarsening of the pattern is a universal behavior for all investigated materials, just at the earliest accessible stage of surface evolution.     

Oxygen vacancy enhanced room temperature ferromagnetism in Ar+ ion irradiated WO3 films

Room-temperature ferromagnetism in WO₃ films was enhanced by 130 keV Ar⁺ ion irradiation. The X-ray diffraction (XRD) and Raman measurements not only confirmed the monoclinic phase of the irradiated WO₃ films, but also showed that oxygen vacancy (V_O) defects were formed. The analysis of photoluminescence spectra strongly reconfirmed the presence of oxygen vacancy. X-ray photoelectron spectroscopy (XPS) measurements revealed that the contents of V_O and induced W⁵⁺ ions increase with increasing irradiation fluence and rich W⁵⁺-V_O defect complexes in the irradiated WO₃ films were formed. Further, the magnetic measurements exhibited a 2-fold enhancement in the saturation magnetization at the largest fluence of 3 × 10¹⁶ ions/cm². At lower irradiation fluence, a bound magnetic polaron model was proposed to reveal the ferromagnetic exchange coupling resulting from overlapping of V_O⁺ and V_O⁺⁺ defect states, and 5d¹ states of W⁵⁺. At high irradiation fluence, the carrier concentration reaches 1.02 × 10²⁰/cm³ and carrier-mediated exchange interactions result in the film's ferromagnetism.     

The mixed-bed ion exchange performance at ultralow concentrations 1. Variable feed concentration and incomplete mixing of resins

Experimental data were obtained to evaluate the performance of mixed-bed ion exchange for the cases of variable feed concentration and incomplete mixing of anion and cation resins observed in large scale industrial units. For variable feed concentration, step changes in feed concentration were arbitrarily introduced into a test column. For incomplete mixing, only anion resin was loaded in the upper 20% of the column and more cation resin in the lower portion. Feed concentrations of 5.0× 10⁻⁵−2.0×10^-4 M NaCl were used for the experiments, with flow rates of 0.665-7.0 ml/sec. The effluent from the column was collected periodically and analyzed using on-line/off-line ion chromatography. The step changes in feed concentration affect the breakthrough times of sodium and chloride. Sodium breakthrough curve is more sensitive to the step changes than chloride breakthrough curve. With the same volumes of cation and anion resins, incomplete mixing of resins increases the cation exchange rate slightly and decreases the anion exchange rate slightly. As the cation resin volume increases, the effect of the incomplete mixing of resins decreases. The breakthrough curves of both ions, plotted as the ratio of effluent to the influent concentration versus run time in hour, give some detailed results about the effects of the conditions.     

Vertically aligned carbon nanotube growth from Ni nanoparticles prepared by ion implantation

Vertically aligned carbon nanotubes (CNTs) were synthesized from Ni nanoparticles prepared by ion implantation. Ni ions were implanted at 30 keV into thermally grown SiO₂ substrates using a focused-ion-beam. High-density nanoparticle formation was investigated with high doses up to 5.0 × 10¹⁷ ions/cm². Dense Ni nanoparticles in the order of 10¹¹–10¹² cm^{− 2} were obtained on a SiO₂ substrate, and the particle density and diameter were controlled by post-implantation annealing. Particles annealed at 700 °C led to vertically aligned CNTs. Interestingly, catalysts were longer along the vertical axis and the lower half of the Ni particle was buried in SiO₂.     

Redox and transport behaviors of Cu(I) ions in TMHA-Tf<Subscript>2</Subscript>N ionic liquid solution

The redox and transport behavior of monovalent copper species in an ammonium imide-type ionic liquid, trimethyl-n-hexylammonium bis((trifluoromethyl)sulfonyl)amide (TMHA-Tf₂N) were examined with a micro-disc electrode to clarify its applicability to, for example, electroplating. It was found that the diffusion coefficient of Cu(I) ions in TMHA-Tf₂N containing 12 mmol dm⁻³ Cu(I) ions was 1.2 × 10⁻⁶ cm² s⁻¹ and the redox potential of Cu(I)/Cu was in the potential range 0.1–0.2 V vs. I ⁻/I ₃⁻ at 50 °C. The diffusion coefficient was one order smaller than that of Cu(II) ions in aqueous solution due to the high viscosity of the ionic liquid. The diffusion coefficient of Cu(I) ion increased with rising temperature and was 1.0 × 10⁻⁵ cm² s⁻¹ at 112 °C, which was comparable to that of Cu(II) ions in aqueous CuSO₄ solutions at ambient temperature. This is accounted for by the drastic decrease in the viscosity of the ionic liquid solution with increasing temperature. The activation energy of diffusion was estimated to be 39 kJ mol⁻¹ in the ionic liquid solution.     

ION-EXCHANGE PROPERTIES OF HYDROUS TITANIUM DIOXIDE WITH A FIBROUS FORM OBTAINED FROM POTASSIUM DITITANATE

ABSTRACT

Ion-exchange properties of a new type of hydrous titanium dioxide with a fibrous form, which was obtained from potassium dititanate (K₂O(TiO₂)2), have been studied. The pH titration curve snowed that this material behaved as a bifunctional ion-exchanger. Distribution coefficients of some divalent metal ions on this material were measured as a function of pH and the selectivity series were found to be Ba > Sr > Ca > Mg for alkaline earth metal ions and Cu > Zn > Mn > Co > Ni for divalent transition metal ions. Large separation factors were obtained between some metal ion pairs and the mutual separations such as Cu from Sr, Ca, Mg, Co and Ni, and Mg from Ba and Zn have been achieved on columns of this material.     

Cation‐exchange kinetics and electrical conductivity studies of an ‘organic‐inorganic’ composite cation‐exchanger: Polypyrrole Th(IV) phosphate

Polypyrrole Th(IV) phosphate, an electrically conducting ‘organic‐inorganic’ cation‐exchange composite material was prepared by the incorporation of an electrically conducting polymer, i.e., polypyrrole, into the matrix of a fibrous type inorganic cation‐exchanger thorium(IV) phosphate. The composite cation‐exchanger has been of interest because of its good ion‐exchange capacity, higher chemical and thermal stability, and high selectivity for heavy metal ions. The temperature dependence of electrical conductivity of this composite system with increasing temperatures was measured on compressed pellets by using four‐in‐line‐probe dc electrical conductivity measuring instrument. The conductivity values lie in the semiconducting region, i.e., in the order of 10^?6 to 10^?4 S cm^?1 that follow the Arrhenius equation. Nernst–Plank equation has been applied to determine some kinetic parameters such as self‐diffusion coefficient (D₀), energy of activation (E_a), and entropy of activation (ΔS*) for Mg(II), Ca(II), Sr(II), Ba(II), Ni(II), Cu(II), Mn(II), and Zn(II) exchange with H⁺ at different temperatures on this composite material. These results are useful for predicting the ion‐exchange process occurring on the surface of this cation‐exchanger. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Modifications in the structural,morphological, optical properties of Ag45Se40Te15 thin films by proton ion irradiation for optoelectronics and nonlinear applications

This current work reports the 30 keV proton ion irradiation induced structural, morphological, and optical properties change in Ag₄₅Se₄₀Te₁₅ films at different fluences. The thin films were irradiated with different ion fluences, such as 5 × 10¹⁵ ions/cm²,1 × 10¹⁶ ions/cm² and 5 × 10¹⁶ ions/cm². The electronic loss (S_e) dominates over the nuclear loss (S_n) in proton irradiation. The X-ray diffraction study shows the phase transformation from amorphous to crystalline upon ion irradiation. The Raman analysis confirms the change in chemical and vibrational bonds due to structural alterations in the films. The surface morphology has been studied by field emission scanning electron microscopy and the composition of the films has been checked by the energy dispersive X-ray analysis. The particle size increased upon the increase in ion irradiation fluence. The surface roughness of the films has been studied by atomic force microscopy. The transmission data is used to calculate the linear optical parameters. The absorption edge shifts towards the high wavelength region inferring the reduction in the optical bandgap. The linear refractive index of the films increased with ion fluence. The optical density increased at the high wavelength region while the skin depth decreased with fluence. The carrier concentration per effective mass decreased while the plasma frequency increased with proton irradiation. The nonlinearity (χ ⁽³⁾ and n₂) values increased significantly with the increase in fluences. Such kind of materials with optimization in their optical parameters are primarily essential for cutting-edge photonic, optoelectronic, and nonlinear optical applications.     

COMPARISON OF ION EXCHANGE AND DONNAN EQUILIBRIUM MODELS FOR THE PH-DEPENDENT ADSORPTION OF SODIUM AND CALCIUM IONS ONTO KRAFT WOOD PULP FIBERS

ABSTRACT

Management of nonprocess element (NPE) accumulation in pulp washing operations requires equilibrium models that predict the distribution of metals between the wash liquor and the pulp fibers. The overall goal of this study was to assess models for predicting the multi-component adsorption of hydrogen ions (H⁺), sodium ions (Na⁺), and calcium ions (Ca⁺²) onto bleached and unbleached kraft pulp fibers over a pH range of 2.7–11. As part of this study, binary equilibrium constants for hydrogen and metal ion exchange on carboxylate sites in bleached pulp (0.041 meq/g dry pulp) were measured at 25°C, with log K ^Na/Ca = ?1.604 ± 0.119, log K ^H/Ca = 0.633 ± 0.087, and intrinsic dissociation constant pK _io of 3.64 ± 0.46. Ion exchange and Donnan equilibrium models adequately predicted the multi-component equilibrium data for competitive adsorption of H⁺, Na⁺, and Ca⁺² onto bleached kraft wood pulp fibers. The ion exchange model was fully predictive, whereas the Donnan model required that the solution pH be known. At pH 2.7–6, the Donnan model predicted the adsorption of Na⁺ and Ca⁺² onto both bleached and unbleached wood pulp fibers better than the ion exchange model. The ion exchange model assumed that residual carboxylate in the pulp served as the only site for the competitive binding of hydrogen and metal ions. In contrast, the Donnan model assumed a non site-specific distribution of metal ions between charged fiber and external solution phases and a carboxylate site specific adsorption of hydrogen ions. Above pH 6, both models failed to predict that the calcium adsorption on unbleached brownstock pulp increased beyond the carboxylate site capacity, suggesting that other functional groups within the brownstock pulp with intrinsic dissociation constant values higher than carboxylate were providing additional binding sites for calcium.     

Purification/annealing of graphene with 100-MeV Ag ion irradiation

Studies on interaction of graphene with radiation are important because of nanolithographic processes in graphene-based electronic devices and for space applications. Since the electronic properties of graphene are highly sensitive to the defects and number of layers in graphene sample, it is desirable to develop tools to engineer these two parameters. We report swift heavy ion (SHI) irradiation-induced annealing and purification effects in graphene films, similar to that observed in our studies on fullerenes and carbon nanotubes (CNTs). Raman studies after irradiation with 100-MeV Ag ions (fluences from 3 × 10¹⁰ to 1 × 10¹⁴ ions/cm²) show that the disorder parameter α, defined by I_D/I_G ratio, decreases at lower fluences but increases at higher fluences beyond 1 × 10¹² ions/cm². This indicates that SHI induces annealing effects at lower fluences. We also observe that the number of graphene layers is reduced at fluences higher than 1 × 10¹³ ions/cm². Using inelastic thermal spike model calculations, we estimate a radius of 2.6 nm for ion track core surrounded by a halo extending up to 11.6 nm. The transient temperature above the melting point in the track core results in damage, whereas lower temperature in the track halo is responsible for annealing. The results suggest that SHI irradiation fluence may be used as one of the tools for defect annealing and manipulation of the number of graphene layers.

PACS

60.80.x; 81.05.ue     

Concentration dependence of electric conductivity for fluorine-containing sodium borate glasses

The influence of sodium fluoride additives on the physicochemical properties of glasses in the Na₂O-B₂O₃ systems is investigated. The introduction of sodium fluoride into the Na₂O · 2B₂O₃ and Na₂O · 3B₂O₃ glasses leads to an increase in the electric conductivity. The temperature-concentration dependence of the electric conductivity has been investigated. It is shown that, in glasses of the NaF-Na₂O · 2B₂O₃ system, an increase in the volume concentration of sodium ions from 2.4 × 10⁻² to ∼3 × 10⁻² mol/cm³ is accompanied by an insignificant decrease in the activation energy E_σ from 1.44 to 1.38 eV and a sharp (by a factor of ∼30) increase in the electric conductivity. In glasses of the NaF-Na₂O · 3B₂O₃ system, an increase in the concentration of sodium ions from 1.8 × 10⁻² to ∼2.3 × 10⁻² mol/cm³ brings about an increase in the electric conductivity by a factor of approximately 100 and an increase in E_σ from 1.6 to 1.83 eV. A further increase in the concentration of sodium ions (up to 2.5 × 10⁻² mol/cm³) virtually does not affect the electric conductivity and E_σ. At the same concentration of sodium ions (∼2.46 × 10⁻² mol/cm³) in the 9.8NaF · 90.2[Na₂O · 2B₂O₃] and 57.1NaF · 42.9[Na₂O · 3B₂O₃] glasses, the electric conductivity and the activation energy are considerably higher in the glass with a larger fluorine content. The regularities revealed are interpreted in the framework of the microinhomogeneous glass structure.     

Concentration dependence of electric conductivity for fluorine-containing sodium borate glasses

The influence of sodium fluoride additives on the physicochemical properties of glasses in the Na₂O-B₂O₃ systems is investigated. The introduction of sodium fluoride into the Na₂O · 2B₂O₃ and Na₂O · 3B₂O₃ glasses leads to an increase in the electric conductivity. The temperature-concentration dependence of the electric conductivity has been investigated. It is shown that, in glasses of the NaF-Na₂O · 2B₂O₃ system, an increase in the volume concentration of sodium ions from 2.4 × 10⁻² to ∼3 × 10⁻² mol/cm³ is accompanied by an insignificant decrease in the activation energy E_σ from 1.44 to 1.38 eV and a sharp (by a factor of ∼30) increase in the electric conductivity. In glasses of the NaF-Na₂O · 3B₂O₃ system, an increase in the concentration of sodium ions from 1.8 × 10⁻² to ∼2.3 × 10⁻² mol/cm³ brings about an increase in the electric conductivity by a factor of approximately 100 and an increase in E_σ from 1.6 to 1.83 eV. A further increase in the concentration of sodium ions (up to 2.5 × 10⁻² mol/cm³) virtually does not affect the electric conductivity and E_σ. At the same concentration of sodium ions (∼2.46 × 10⁻² mol/cm³) in the 9.8NaF · 90.2[Na₂O · 2B₂O₃] and 57.1NaF · 42.9[Na₂O · 3B₂O₃] glasses, the electric conductivity and the activation energy are considerably higher in the glass with a larger fluorine content. The regularities revealed are interpreted in the framework of the microinhomogeneous glass structure.     

Lysine Adsorption on Cation Exchange Resin. IV. Temperature Effects on Equilibrium and Kinetics in Batch and Column Systems

Abstract

Ion exchange equilibria and kinetics are determined for lysine adsorption on the strong acid cation exchanger DIAION SK‐1B at temperatures of 25, 40, and 60°C. The ion exchange equilibrium is found to be independent of temperature. Conversely, the kinetics of ion exchange increases dramatically as the temperature is increased. Average ion exchange selectivity coefficients of 6.0 g/cm³ and 0.52 are obtained for the ion exchange of divalent and monovalent cationic lysine with hydrogen ion, respectively. Resin phase diffusivities are determined by fitting batch binary ion‐exchange data with a mass transfer model based on the Nernst‐Planck equations. As the temperature is increased from 25 to 60°C, the resin phase diffusivity increases from 0.04×10^?6 to 0.14×10^?6 cm²/s for divalent lysine and from 0.16×10^?6 to 0.55×10^?6 cm²/s for monovalent lysine. The combination of temperature‐independent ion exchange equilibria and faster mass transfer at higher temperatures results in higher dynamic binding capacity and more efficient desorption of lysine when ion exchange is operated at an elevated temperature. This behavior is confirmed by means of column adsorption/desorption experiments whose results are found to be in agreement with a model incorporating the equilibrium and mass transfer data obtained in this work.     

Infrared spectra of dinitrogen adsorbed on bimetallic lanthanide (Eu or Yb)–Ni/SiO2 catalysts

Bimetallic lanthanide (Ln: Eu or Yb)–Ni/SiO₂ catalysts prepared by the use of dissolution of lanthanide metals in liquid ammonia have been studied by infrared spectroscopy for dinitrogen adsorption. The infrared spectra were measured at 133–300 K using Ln–Ni/SiO₂ obtained when the Eu or Yb metal dissolved in liquid ammonia reacted with 20 mass% Ni/SiO₂ in different ratios. Infrared spectra for Eu–Ni/SiO₂ showed absorption bands at 2336, 2265, 2254 and 2227 cm⁻¹ at 133 K, which disappeared upon evacuation. The adsorbed state was found to be all molecular from the isotope shift using ²⁸N₂ and z³⁰N₂₈. The bands at 2254 and 2227 cm⁻¹ of them were assigned to new adsorbed dinitrogen species resulting from synergetic interactions between the europium and nickel metal. The concentration of adsorbed dinitrogen on Eu–Ni/² varied markedly with the Eu/Ni ratios, and particularly, it increased in the region of high Eu content. Upon introduction of ytterbium onto nickel, new bands at 2254 and 2226 cm^−- similarly appeared. However, the dependence of dinitrogen adsorption as a function of Yb content in Yb–Ni/SiO²> was somewhat different from that for Eu–Ni/SiO₂. The effects of lanthanide on the surface of Ln–Ni/SiO₂ were discussed in connection with the variation in catalytic properties. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of semiconducting polyphenylacetylene catalyzed by Ni(MeCN)6(BF4)2/AlEt2Cl

Summary Phenylacetylene (PhA) is polymerized by the dicationic nickel complex Ni(MeCN)₆(BF₄)₂ associated with AlEt₂Cl as co-catalyst. The production of 200g of polymer per gram of nickel per hour represents a typical activity of this system. Under our experimental conditions, the polymer displays an exclusive trans structure. The molecular weight distribution of the polymer is polymodal (5000 g.mol⁻¹ and 200 g.mol⁻¹). The highest average molecular weight fraction (5000 g. mol⁻¹) represents the highest published value for polyphenylacetylene (PPA) where a nickel catalyst is employed. The electrical conductivities vary between 10⁻⁷ and 10⁻¹⁶ S.cm⁻¹, and are characteristic of a semi-conductor polymer. Equivalent values are cited in the literature only in the case of doped PPA. Experimental observations enabled us to propose a mechanism for the formation of the active species through the reaction of Ni(MeCN)₆(BF₄)₂ with AlEt₂Cl. Received: 13 September 2001/Revised version: 10 January 2002/ Accepted: 11 January 2002     

Some aspects of glass formation in R′2O−P2O5 and R″O−P2O5 systems

The limits of the glass-formation regions are established for the binary R′₂−P₂O₅ and R″O₅−P₂O₅ systems (R′=Li, Na, K: R″=Mg, Ca, Sr, Ba). It is shown that these boundaries closely correlate with those reported by other investigators despite the difference in the conditions in which these binary phosphate glasses were synthesized. The fact that all of the systems under study have about the same upper limits of glass-formation regions is attributed to the ratio R′₂O(R′O): P₂O₅, which for the systems in question is 1.0–1.5 rather than the individual crystal-chemical characteristics of the R⁺ and R²⁺ cations. Translated from Steklo i Keramika, No. 2, pp. 13–15 February, 1997.     

Uniform coating of a crystalline TiO2 film onto steel plates by electrochemical deposition using staged pulse current

A crystalline TiO₂ (c-TiO₂) film was electrochemically deposited onto a 10 cm × 20 cm hot-dip-galvanized (HDG) steel plate at 60 °C from an alkaline aqueous solution containing 0.1 M titanium potassium oxalate dehydrate and 1 M hydroxylamine. The electrochemical deposition was carried out by a galvanostatic method. First, a current density of 10 mA cm⁻² was applied for 5 min, which led to the formation of a uniform coating of TiO₂ on a 1 cm × 1 cm small HDG plate. A crystalline layer was observed, however, only in the central area, whereas the upper and the edge areas were amorphous. Both calculations and experiments confirmed that this was due to the difference of the local current densities in the vicinities of different areas. Next, three different currents (5 mA cm⁻² (2 min), 10 mA cm⁻² (2 min) and 20 mA cm⁻² (1 min)) were applied continuously so that the local current density for each part of the substrate achieved appropriate deposition conditions. The film thus obtained was crystalline in all areas and of uniform thickness.