Multicomponent Ion Research Articles

Modern Theory for Multicomponent Ion Exchange Equilibria and Chromatographic System Behavior in Columns

Theoretical description, including computerized simulation of the dynamic behavior of multi-component ion exchange (IEx) chromatographic systems for the displacement-elution regime in column is presented. Multi-component IEx equilibria used for the simulation of IEx dynamics have been described by the modern theoretical approach called by the German authors as the “Surface Complexation Theory” (SCT-Model). The main proposal in the SCT-Model is that the fixed groups of any ion exchanger form Surface Complexes with counter-ions of the components. By computerized simulation the dynamic behavior of the multi-component concentration waves formed by the displacer ions (H+ or Na+) including two various components Me1 + and Me2 + eluted during the displacement-elution dynamics in the IEx columns is analyzed. The term “wave” reflects one of the fundamental concepts applied in the theory of chromatography.[1–3] The behavior depends on SCT-parameter values, used in the SCT-Model for multi-component equilibria. The experimental SCT-parameters obtained previously for a number of ion exchangers are used for the computerized simulation of the dynamic processes on the basis of differential mass balance equations.

Influence of ion source configuration and its operation parameters on the target sputtering and implantation process

In the work, investigation of the features and operation regimes of sputter enhanced ion-plasma source are presented. The source is based on the target sputtering with the dense plasma formed in the crossed electric and magnetic fields. It allows operation with noble or reactive gases at low pressure discharge regimes, and, the resulting ion beam is the mixture of ions from the working gas and sputtering target. Any conductive material, such as metals, alloys, or compounds, can be used as the sputtering target. Effectiveness of target sputtering process with the plasma was investigated dependently on the gun geometry, plasma parameters, and the target bias voltage. With the applied accelerating voltage from 0 to 20 kV, the source can be operated in regimes of thin film deposition, ion-beam mixing, and ion implantation. Multi-component ion beam implantation was applied to α-Fe, which leads to the surface hardness increasing from 2 GPa in the initial condition up to 3.5 GPa in case of combined N(2)-C implantation. Projected range of the implanted elements is up to 20 nm with the implantation energy 20 keV that was obtained with XPS depth profiling.

Modeling Sorbent Phase Nonideality for the Accurate Prediction of Multicomponent Ion Exchange Equilibrium with the Homogeneous Mass Action Law

In this Article the ion exchange equilibrium of binary and multicomponent systems was modeled with homogeneous mass action law using activities and taking account of the partial dissociation of sal...

Effect of light gas atom inclusions on the characteristics of laser-produced plasma ions

Using the mass-spectrometric method we studied the effect of light gas inclusions on the formation process of multi-component laser-induced plasma ions. Mass–charge characteristics, as well as energy and spatial distribution of the plasma ions are analysed. We found that both the energy and maximal charge of heavy component ions decrease due to the presence of gas atoms in the solid target surface layer.

Micro‐modeling of porous composite anodes for solid oxide fuel cells

AbstractA new anode micromodel for solid oxide fuel cells to predict the electrochemical performance of hydrocarbon‐fuelled porous composite anodes with various microstructures is developed. In this model, the random packing sphere method is used to estimate the anode microstructural properties, and the complex interdependency among the multicomponent mass transport, electron and ion transports, and electrochemical and chemical reactions is taken into account. As a case study, a porous Ni–YSZ composite anode operated with biogas fuel is simulated numerically and distributions of the current density, polarization, and mole fraction and rate of flux of the fuel components along the thickness of the anode are determined. The effect of the anode microstructural variables including the porosity, thickness, particle‐size ratio, and particle size and volume fraction of Ni particles on the anode electrochemical performance is also studied. © 2011 American Institute of Chemical Engineers AIChE J, 58: 1893–1906, 2012

Synthesis and Characterization of Novel Materials, Tin Potassium Vanadate and Zirconium Potassium Vanadate Inorganic Multi-Component Ion Exchangers

Nano polyoxometallate-cation exchangers, tin potassium vanadate (TPV), and zirconium potassium vanadate (ZPV), with stereoregular particulate structures have been chemically synthesized using a homogeneous precipitation technique under a variety of conditions. The experimental parameters such as mixing, volume ratio, order of mixing and pH were established for the synthesis of the materials and fairly compromised to optimize the ion exchange properties of the produced ion exchangers. Structural characterizations of the materials were performed using XRF, XRD, thermal analysis, surface area and porosity measurements, and infra-red spectroscopy. The results were correlated to the lattice parameters, unit cell parameters, and space group of the exchangers. Scanning electron microscopy and atomic force microscopy revealed their sereoregularity in space. Compositions and molecular formulae of both the amorphous and crystalline materials have been investigated. Ion exchange properties and distribution coefficients, K d , for some heavy metals namely, Co2+, Cu2+, Ni2+, and Cr6+ were measured at different pH values. TPV and ZPV selectivities have been examined by achieving some important and analytically difficult binary and multi-component separations. The results indicated that TPV is practically utilized for best separation of Co2+/Cu2+, Ni2+/Co2+, Cr6+/Co2+, Ni2+/Cu2+, Cr6+/Cu2+, Ni2+/Cr6+, Ni2+/(Co2+, Cu2+), and Ni2+/(Co2+, Cu2+, Cr6+), while ZPV could be efficiently used for separation of Cu2+/Co2+, Ni2+/Co2+, Cr6+/Co2+, Cu2+/Ni2+, Cr6+/Cu2+, Cr6+/Ni2+, and Cr6+/(Co2+, Cu2+, Ni2+).

Hollow beam formation in the intense multi-component heavy ion beam caused by beam self-field

The simulation of the hollow beam formation in the intense multi-component ion beam from ECR source is fulfilled. The influence of the helium and hydrogen beam current on the argon and calcium ions dynamics has been studied.

Generation of multicomponent ion beams by a vacuum arc ion source with compound cathode

This paper presents the results of time-of-flight mass spectrometry studies of the elemental and mass-to-charge state compositions of metal ion beams produced by a vacuum arc ion source with compound cathode (WC-Co(0.5), Cu-Cr(0.25), Ti-Cu(0.1)). We found that the ion beam composition agrees well with the stoichiometric composition of the cathode material from which the beam is derived, and the maximum ion charge state of the different plasma components is determined by the ionization capability of electrons within the cathode spot plasma, which is common to all components. The beam mass-to-charge state spectrum from a compound cathode features a greater fraction of multiply charged ions for those materials with lower electron temperature in the vacuum arc cathode spot, and a smaller fraction for those with higher electron temperature within the spot. We propose a potential diagram method for determination of attainable ion charge states for all components of the compound cathodes.

Nuclear fusion reaction rates for strongly coupled ionic mixtures

We analyze the effect of plasma screening on nuclear reaction rates in dense matter composed of atomic nuclei of one or two types. We perform semiclassical calculations of the Coulomb barrier penetrability taking into account a radial mean-field potential of plasma ions. The mean-field potential is extracted from the results of extensive Monte Carlo calculations of radial pair distribution functions of ions in binary ionic mixtures. We calculate the reaction rates in a wide range of plasma parameters and approximate these rates by an analytical expression that is expected to be applicable to multicomponent ion mixtures. Also, we analyze Gamow-peak energies of reacting ions in various nuclear burning regimes. For illustration, we study nuclear burning in $^{12}\mathrm{C}$-$^{16}\mathrm{O}$ mixtures.

Ion adsorption behaviour of hydroxyapatite with different crystallinities

This study aimed to correlate crystallinity of hydroxyapatite (HA) with the ion adsorption behaviour of the material. Hydroxyapatite powders of various crystallinities ( X c) and specific surface area (SSA) were prepared by precipitation following heat treatment. Adsorption experiments were carried out by using (i) multi-component ion solutions containing a broad range of light and heavy ions to study competitive adsorption and (ii) lead and zinc solutions with concentrations up to 250 ppm to determine the adsorption isotherms of the material. While as-prepared HA powders of low crystallinity ( X c = 0%) and a high SSA of 170 m 2/g showed quantitative removal for divalent Pb, Zn, Be, U, Bi, V, Al, Cu and Ga ions, calcined powders with higher crystallinity ( X c = 65–95%) and lower SSA between 5 and 30 m 2/g led to a quantitative removal only for a few elements (Pb, Bi, Ga). The time and concentration dependant ion removal capacity for Pb 2+ and Zn 2+ single element solutions showed quantitative removal even after short immersion times of less than 10 min for as-prepared HA powders. XRD analysis of the powders after ion adsorption revealed the presence of pyromorphite (Pb 5(PO 4) 3OH) and hopeite (Zn 3(PO 4) 2) phases, respectively.

Solvent effects during multicomponent ion uptake into a Nafion cation-exchange membrane

A multicomponent ion partition coefficient model has been used to predict competitive alkali metal ion uptake into a Nafion ® cation-exchange membrane from solvents composed of methanol, methanol/water, and acetonitrile/water. The analysis was similar to that used previously for monovalent and divalent uptake and transport in Nafion, where the membrane was modeled as an array of parallel cylindrical pores of constant radius with a continuous distribution of fixed charges along the pore wall. Ion–ion electrostatic interactions, electric-field induced solvent dipole alignment, and ion solvation free energy effects were taken into account. In the present study, the model was modified to account for a different solvent composition in the membrane, as compared to that in the external solution (solvent uptake data were collected experimentally). The model accurately predicted competitive K +/Na + uptake from methanol and methanol/water mixed solvents and Cs +/K + uptake selectivities for acetonitrile/water solvents. In the latter case, model calculations suggested that some acetonitrile absorbed into the amorphous PTFE phase of Nafion, when the external acetonitrile concentration was greater than 33 vol%. The addition of water to methanol caused a drop in the potassium/sodium selectivity (to its pure water value), whereas the addition of acetonitrile to water caused the Cs +/K + selectivity to decrease.

Multicomponent ion exchange isotherms in NaX zeolite: evaluation of Cr/Ca/Mg, Cr/Ca/K and Cr/Mg/K systems

AbstractBACKGROUND: One of the most important heavy metals is Cr3+, which is commonly found together with Ca2+, Mg2+ and K+ ions in tannery wastewaters. Such metals can be removed through ion exchange process using zeolite NaX. Unfortunately, with single exchange mechanisms it is impossible to predict muti‐component and competitive interactions. This work is aimed at overcoming this problem. Ion exchange isotherms of Cr3+, Mg2+, Ca2+ and K+ in ternary mixtures (Cr/Mg/Ca, Cr/Ca/K, Cr/Mg/K) using NaX zeolite at 30 °C, 45 °C and 60 °C are studied and reported.RESULTS: Ion exchange is dependent on temperature, and on the nature and interaction of ingoing cations. Sequential ion exchange occurs where one cation is able to displace another already located in the site. Values of the equilibrium constant of all cations investigated are close to each other, which indicates a weak preference for Cr+3. The affinity order is as follows: for Cr/Ca/Mg–NaX isotherms, Cr3+ > Ca2+ > Mg2+ at 30 °C, Ca2+ > Cr3+ > Mg2+ at 45 °C and Ca2+ > Mg2+ > Cr3+ at 60 °C. For Cr/Ca/K–NaX isotherms the sequence is Cr3+ > Ca2+ > K+ for the three temperatures and for Cr/Mg/K–NaX isotherms, Cr3+ > Mg2+ > K+ at 30 and 45 °C and Mg2+ > K+ > Cr3+ at 60 °C.CONCLUSION: It can be concluded that ions with a high charge such as Cr3+ are not always preferentially removed from multi‐component solution. Therefore, exchanges in NaX zeolite are useful when there is no need to have high chromium removal when compared to the competitive cations investigated here. Copyright © 2008 Society of Chemical Industry

Improving the Performance of a Quadrupole Time-of-Flight Instrument for Macromolecular Mass Spectrometry

We modified and optimized a first generation quadrupole time-of-flight (Q-TOF) 1 to perform tandem mass spectrometry on macromolecular protein complexes. The modified instrument allows isolation and subsequent dissociation of high-mass protein complexes through collisions with argon molecules. The modifications of the Q-TOF 1 include the introduction of (1) a flow-restricting sleeve around the first hexapole ion bridge, (2) a low-frequency ion-selecting quadrupole, (3) a high-pressure hexapole collision cell, (4) high-transmission grids in the multicomponent ion lenses, and (5) a low repetition rate pusher. Using these modifications, we demonstrate the experimental isolation of ions up to 12 800 mass-to-charge units and detection of product ions up to 38 150 Da, enabling the investigation of the gas-phase stability, protein complex topology, and quaternary structure of protein complexes. Some of the data reveal a so-far unprecedented new mechanism in gas-phase dissociation of protein oligomers whereby a tetramer complex dissociates into two dimers. These data add to the current debate whether gas-phase structures of protein complexes do retain some of the structural features of the corresponding species in solution. The presented low-cost modifications on a Q-TOF 1 instrument are of interest to everyone working in the fields of macromolecular mass spectrometry and more generic structural biology.

Removal of Multiple-Metals from Contaminated Clay Minerals

Clay minerals spiked with multi-component metal ions (Cu+2, Cd+2, Pb+2) were decontaminated using different soil washing solutions. The desorption characteristics were determined by batch acid leaching with various acids. Removal of Cu+2, Cd+2 and Pb+2 ions from variable charge minerals (e.g. kaolinite) required much less effort than their removal from constant-charge minerals (e.g. illite). The surface charge of a clay mineral had an important influence. When the numbers of H+ and Na+ ions available in the soil were increased by adding a buffer solution such as NaOAc-HOAc, heavy metals adsorbed on the clay surface transferred to the pore fluid. When more H+ or Na+ ions were available in the pore fluid, more Cu+2, Cd+2 and Pb+2 ions were released into the equilibrium solution. Decreasing the pH led to more removal of heavy metal ions from kaolinite. The presence of Na+ ions facilitated the removal of heavy metals from contaminated illite. The selectivity for desorption was in the order Cu+2>Cd+2>Pb+2 for all washing solutions investigated.

Transportation and charged separation of multicomponent ions beam in plane gap (abstract)

In this research a problem of variously charged ion beam transportation in plane equipotential gap is solved. There were received values of critical current densities for such a beam in dependence of current density and average beam charge going through the gap on current density, average charged, and initial energy of ions of injected beam. There were conditions found where the effective separation of doubly charged and singly charged ions happens.

Monitoring of Zn(II) and Cd(II) adsorption on activated carbon from aqueous multicomponent solutions by differential pulse polarography (DPP)

The adsorption process of Zn(II) and Cd(II) from aqueous solution has been investigated from both kinetic and equilibrium standpoints, using differential pulse polarography (DPP) on a mercury dropping electrode as the analytical technique. With such an aim, adsorption experiments were performed using not only a single metal ion–Zn(II) or Cd(II) solution but also a multi-component ion metal–Zn(II), Cd(II) and Hg(II) solution. The influence of the pH change in the multi-component ion metal solution on the adsorption of Zn(II) and Cd(II) was also studied. The adsorption processes is relatively fast for Zn(II) and Cd(II). The presence of two foreign ions in the solution slightly speeds up the adsorption process for Zn(II) and significantly slows it down for Cd(II). The adsorption isotherms are similarly shaped for Zn(II) and Cd(II). The addition of the foreign ions has a more unfavourable effect on the adsorption for Cd(II) than for Zn(II). At pH 2, neither Zn(II) nor Cd(II) is adsorbed practically on the carbon. The voltammetric approach has proved to be a fast and efficient method that, at the same time, enables one to monitor the adsorption of Zn(II) and Cd(II) with potential on-line application, which could be useful in waste-water treatment.

Particle-in-cell method for numerical simulation of beam and plasma dynamics

The finite particle methods are widely applied for the numerical simulation of a continuous medium including continuum electrodynamics and simulation of charged particle beams. This method allows studying the detailed beam and plasma characteristics, the distribution function of particles, the nonlinear self and external fields. The so-called “particle-in-cell” method is the most effective for simulations in the physics of plasma and charged particle beams. Two examples illustrate the application of the particle-in-cell method in beam dynamics and plasma physics. The first is a program library for numerical simulation and optimization of multi-component ion beam transportation from ion sources where RFQ accelerators are presented. The latest version of the library was applied for simulations of transverse dynamics of an argon ion beam in the beam line from the 18 GHz ECR Ion Source to the linear RFQ accelerator of the RIKEN Beam Factory. A partial neutralization of ion beam charge due to secondary electrons was assumed to realize the real experimental conditions in the beam line and was used in simulation. The second is a summary of recent development of physical and mathematical basements and the first version of a computer code library aimed for the three-dimensional (3D) simulation of the ECR plasma and ion production in the ECR ion source.

Modeling Solution Phase Behavior in Multicomponent Ion Exchange Equilibria Involving H+, Na+, K+, Mg2+, and Ca2+ Ions

Eight different ion exchange equilibrium models are tested to determine which gives the most accurate predictions of equilibrium behavior for multicomponent ion exchange. The eight models differ only in the way in which they account for solution phase phenomena. Nonidealities in the exchanger phase are accounted for by applying the Wilson model. The solution phase models considered include a model that assumes ideal solution behavior and others that apply the extended Debye−Huckel equation, the Meissner and Kusik electrolyte solution theory, and the Pitzer electrolyte solution theory. Each of these methods for accounting for solution phase nonidealities are applied twice, once assuming incomplete ion dissociation and once assuming that ion dissociation was complete. The models are tested using an extensive set of equilibrium data for the 10 binary, 10 ternary, 5 quaternary, and 1 quinternary systems involving exchange of the five H+, Na+, K+, Mg2+, and Ca2+ cations on a commercial resin. The results show ...

Observation of structural changes in carbon films under external influences

Carbon films obtained by the plasma chemical deposition method from the multicomponent stream of ionized particles on the various substrates are investigated. Structural formations with parallel lines were observed under the microscope on the film surface. Apparently, charge accumulation takes place along these lines. When the film locally is heated then micro tube-like structure peculiarities are formed along these lines. Observed peculiarities are periodic in nature with well-established formation phases. Possibly, the charge accumulation lines coincide with the micro tube-like formations as our observations revealed. It is important to stress that the parameters of micro tube-like formations, i.e., the period of sinus-like formations and their linear dimensions are dependent on the technological parameters. Metal–carbon film-Si sandwich-like system's volt–ampere characteristics show irreversible breakdown due to structural changes taking place in system and being observed microscopically. Obviously, this is due to applied strong electric fields (∼10 5–10 6 V/cm). Thus, origination of micro- and nano-formations both on the surface and in the bulk of carbon films under strictly controlled conditions is possible to obtain from multicomponent ion streams.

Ionic transport through ion-exchange and bipolar membranes

Problems of steady-state and non-steady-state multi-component ion transport through ion-exchange and bipolar membranes and adjacent diffusion layers are considered. Equations of material balance of electrolyte components and the Poisson equation are used as the mathematical model. An efficient numerical method providing splitting of equations of material balance of electrolyte components and the Poisson equation is proposed. The method requires no explicit consideration of interfaces and the use of Donnan equations; it provides exact fulfillment of boundary conditions both for the mode of constant current density and for the mode of constant voltage. The following results of simulating the ion transport through ion-exchange and bipolar membranes and adjacent diffusion layers are presented: the distributions of concentrations, electrical potential, charge, and partial current densities and the voltammograms of electromembrane systems.