Two-step Ion-exchange Process Research Articles

Synthesis and characterization of a di-methacrylated polymerizable ionic liquid through two-step esterification and ion exchange process

An effective two-step synthesis for the di- methacrylation of 2-hydroxylethylammonium chloride ionic liquid was developed in the presence of methacrylic anhydride. The esterification process was performed through the hydroxyl moiety and the side product methacrylic acid was effectively captured through an ion exchange process via sodium bicarbonate to yield a polymerizable di- methacrylate monomer. The esterification and ion exchange processes were monitored via titrations and spectroscopy. This low viscosity (62 cP) di- functional modified ionomer is thermally homo-polymerized and co-polymerized with 55 wt% bis-GMA as a nonvolatile reactive diluent yielding impressive glass transition temperature (Tg) values up to 157 °C and 170 °C for homo- and co- polymer respectively as determined via differential scanning calorimetry method.

Metal-organic frameworks-derived carbon modified wood carbon monoliths as three-dimensional self-supported electrodes with boosted electrochemical energy storage performance

Wood-derived carbon monoliths, in recent years, have attracted tremendous interest in the field of energy storage, but their electrochemical characteristics are still far from satisfactory. Here, we report a universal and efficient approach for the preparation of structure-engineered, heteroatom-functionalized and property-boosted wood carbons. A two-step ion-exchange process greatly enriches the nucleation sites of ZIF-8 on the inner wall of wood tracheids, hence leading to a unique carbon/carbon heterostructure after carbonizing and acid-washing. Particularly, the prepared NPCM-900 with a large specific surface area of 708.2 m2 g−1, a hierarchical porous architecture and a suitable N content of 2.3% delivers an ultrahigh area-normalized specific capacitance of 23.7 F cm−2 at 5 mA cm−2, which stands for a new capacitive record among the wood-based binder-free electrodes. The NPCM-900//NPCM-900 all-solid-state supercapacitor has an admirable energy density of 9.3 Wh m−2 at 24.9 W m−2 and a large power density of 248.3 W m−2 at 4.8 Wh m−2, while the NPCM-900 based Zn-ion hybrid supercapacitor (NPCM-900//Zn) exhibits a superior energy density of 12.7 Wh m−2. Furthermore, the NPCM-900//NPCM-900 and NPCM-900//Zn present great stabilities with capacitance retentions of 87% and 85%, respectively, after 5000 cycles. These parameters notably outperform those of most wood-based supercapacitors, endowing the NPCM-900 with extensive prospects for practical use.

Bimetallic CoSe2/FeSe2 hollow nanocuboids assembled by nanoparticles as a positive electrode material for a high-performance hybrid supercapacitor.

Design and fabrication of impressive and novel electrode materials for energy storage devices, especially supercapacitors, are of great importance. Herein, bimetallic CoSe2/FeSe2 hollow nanocuboid nanostructures derived from Co/Fe-Prussian Blue analogues (denoted as CoSe2/FeSe2 HNCs) are successfully designed and fabricated as a remarkable positive electrode material for high-performance supercapacitors. The bimetallic CoSe2/FeSe2 HNC nanostructures can have increased active sites and short electron-ion diffusion pathways. Bimetallic CoSe2/FeSe2 HNCs@NiF as a positive electrode showed efficient supercapacitive properties with a great specific capacity of 332.75 mA h g-1 (1197.90 C g-1) at 1 A g-1, retaining 80.61% of its initial capacity at 20 A g-1, considerable longevity (91.47% of its initial capacity after 10 000 cycles) and an excellent coulombic efficiency of 98.49%. Also, the designed and fabricated CoSe2/FeSe2 HNCs@NiF||AC@NiF hybrid supercapacitor device using bimetallic CoSe2/FeSe2 HNCs@NiF (positive electrode) and activated carbon@NiF (AC, negative electrode) exhibited an efficient energy density of 63.62 W h kg-1 and a superior durability of 91.14% after 10 000 cycles.

Chemical strengthening of Li+-containing phosphosilicate glass via a two-step ion-exchange process

Chemical strengthening of Li+-containing phosphosilicate glass via a two-step ion-exchange process

Cadmium ions sequestration and transformation on confined magnesium hydroxide gel beads

Powdered magnesium hydroxide (MH) has the advantages of high activity, low cost and environmental friendliness, while it faces difficulties in recovery and solid-liquid separation after being used in an aqueous solution. In this study, magnesium hydroxide confined in millimeter-sized chitosan xerogel beads (CXB@MH) were constructed for the first time via facile sol-gel process. High loading (47.7 wt%) and uniform dispersion of MH nanosheets inside CXB@MH endowed it with excellent removal capacity (234.0 mg/g). The macroscopic property of the CXB@MH allowed it easy to recycle from aqueous solution and can be filled in a fixed bed for dynamic Cd2+ removal. Cd2+ ions were removed on the surface of CXB@MH by two-step ion exchange process: first an intermediate Cd(OH)2 were formed, followed by conversion to CdCO3 under ambient air. This work provides a reference for the preparation of analogous support-based nanocomposites for water treatment.

Anion exchange separation of antimony and the integrated ion exchange process for decontamination of used zircaloy pressure tubes from Indian pressurized heavy water reactors

ABSTRACT A two-step ion exchange process has been developed for decontamination of used pressure tube zircaloy, from pressurized heavy water reactors, with respect to 125Sb and 60Co. The steps are: anion exchange separation of Sb (III) and cation exchange separation of Co (II); from Zr (IV). Our earlier results on distribution coefficients, isotherms and kinetic separation of Co were the erecting pillars of the present integrated separation process. Oxidation state of Sb in the feed solution, need for reduction of Sb (V) to Sb (III), the nature and amount of reagents required were investigated. Effect of Zr concentration on uptake of Sb and Co, resin capacity, requirement, column dimensions, and flow rate was evaluated.

High performance CdSe quantum dot sensitized ZnO solar cell fabricated from ion exchange

We report on a facile and efficient way to prepare CdSe/ZnO photoanode for quantum dot sensitized solar cell (QDSSC). CdSe/ZnO is achieved through a two-step ion exchange process in aqueous solution at lower temperature. SEM, light absorption, dark current and impedance spectroscopy analyses revealed that this process of ion exchange can form not only higher amount and larger sized QDs on ZnO that lead to the enhancement of light harvesting, but also full coverage of QDs on ZnO as well as excellent QD/ZnO interfaces that contribute to the suppression of charge recombination. In combination with ZnSe overcoating, QDSSC assembled with the CdSe/ZnO photoanode exhibits high cell efficiency of 5.08%.

Inverse modeling of buried, ion-exchanged glass waveguides using an adjoint method

Buried glass waveguides can be fabricated using two-step ion-exchange processes. According to Fick’s law these processes can be mathematically described with the diffusion equation. We demonstrate in this work an approach based on an adjoint method to evaluate the gradient of the inverse model of one-dimensional two-step ion-exchange processes. The approach shows a consistent and efficient calculation of the gradient in comparison to the finite difference method.

Large Optical Backplane With Embedded Graded-Index Glass Waveguides and Fiber-Flex Termination

Introduction of electro-optical circuit board (EOCB) technologies based on embedded glass waveguides in the system enclosure of current data storage, compute, or switch platforms will be instrumental in accommodating the prohibitive bandwidth densities projected in exascale data centers, access networks, and high-performance computing environments in future. The main focus of this paper is, therefore, on the realization of large EOCB backplanes (350 × 465) mm2 with passive dual-star interconnect topologies. The waveguides are embedded inside glass panels using a two-step thermal ion exchange process [1] . The fabricated embedded waveguides are then characterized for propagation and coupling losses across different wavelength ranges and for different coupling arrangements. The fabrication process for these large panels is briefly explained accompanied by the lamination process of four separate glass panels. The connectivity between backplane and peripheral cards is addressed using fiber flex termination with two possible waveguide interfaces—actively assembled pluggable interface and passively assembled adhesive bonded interface. A demonstration platform is also finally reported and the viability evaluated for optical connectivity and system efficiency is tested for the whole system containing fiber flex termination.

RuOx nanoparticles deposited on TiO2 nanotube arrays by ion-exchange method as electrocatalysts for the hydrogen evolution reaction in acid solution

Nanocomposite cathodes for the hydrogen evolution reaction (HER) were prepared by deposition of RuOx catalyst particles on self-organized titania nanotube (TiNT) arrays of highly developed surface area, following a procedure that involved the initial cathodic intercalation of H+ into the TiNT walls and the subsequent two-step ion-exchange process. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) analyses of obtained Ru-TiNT samples revealed that the concentration of RuOx particles in the size range of a few nanometers was the highest at the surface of the TiNT layer and steadily decreased to a minimum value at about 4.5μm inside the tubes. The capacitive behavior and electrocatalytic activity for the HER of Ru-TiNT nanocomposites, hydrogenated TiNT samples (H-TiNT) and compact TiO2 were investigated in 1.0M HClO4 solution at room temperature by means of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis and steady-state polarization measurements. It was shown that cathodic hydrogenation treatment induced a four orders of magnitude higher concentration of electron donors in TiNT structures providing their quasimetallic behavior in the range of potentials corresponding to the HER. Ru-TiNT cathodes exhibited a more than 250mV lower overpotential for the HER with respect to bare H-TiNT substrates at the current density of –50mAcm−2. A decrease of the Tafel slope from about –120mV/dec for H-TiNT samples to as low as –70mV/dec for the Ru-TiNT sample with longer tubes was explained by the formal kinetics approach.

Pluggable Electro-Optical Circuit Board Interconnect Based on Embedded Graded-Index Planar Glass Waveguides

Widespread adoption of electro-optical circuit boards based on embedded glass waveguide technology would enable seamless optical connectivity from external fiber-optic networks to system embedded optical interconnect architectures. In this paper, we report on the fabrication of planar multimode waveguides within thin glass foils based on a two-step thermal ion exchange process. Novel lamination techniques were developed to allow glass waveguide panels to be reliably integrated into a conventional electronic multilayer printed circuit board. In addition, a complete suite of optical connector technologies were developed to enable both direct fiber-to-board and board-to-board connectivity. We present the design, development, and characterization of a fully integrated connection platform, comprising a $281 \times 233$ mm2 multilayer electro-optical backplane with integrated planar glass waveguides, a pluggable connector system, and five pluggable test cards. Both on-card and externally generated 850 and 1310-nm optical test data were conveyed through the connector and waveguide system and characterised for in-system and system-to-system optical connectivity at data rates up to 32 Gb/s per channel exhibiting bit error rates of less than $10^{-12}$ .

Fabrication of gradient refractive index rod lens using double ion exchange processes

A theoretical model for calculating the refractive index profile of gradient refractive index rod lens is established. Gradient refractive index rod lenses are prepared using double ion exchange processes, and their optical characteristics have been evaluated for the first time to the best of our best knowledge. The theoretical and the experimental results show that they agree well with each other. Moreover, the refractive index profile and the optical performance of gradient refractive index rod lens in the two-step ion exchange process are superior to them in the one-step ion exchange process.

Ag nanoparticles embedded in glass by two-step ion exchange and their SERS application

Silver nanoparticles embedded in glass are prepared by a two-step ion exchange process, where silver ions are introduced into glass in silver ion exchange, and reduced into metallic silver in subsequent potassium ion exchange. The formation of the particles can be explained by the combination effect of the galvanic replacement reaction and the electrolytic deposition. The formed particles are characterized by optical absorption measurements, transmission electron microscopy and atomic force microscopy. Their application in SERS is demonstrated, and the optimal surface features in terms of SERS enhancement are also discussed.

Multistep ion exchange processes of gradient refractive index rod lens

A mathematical model for research on the refractive index profile (RIP) of multistep ion exchange processes (IEPs) of gradient refractive index rod lenses (GRINs) is established by the different initial condition and boundary condition, based on the Fickian diffusion equation. GRIN rod lenses have been fabricated using the three-step IEPs. Research results indicate that the experimental deviations of refractive index (DRI) are in good agreement with the theoretical data. The DRI of three-step IEPs is superior to the one- and two-step IEPs and smaller than 10(-5).

Comparison of single-step and two-step purified coagulants from Moringa oleifera seed for turbidity and DOC removal

The coagulant proteins from Moringa oleifera purified with single-step and two-step ion-exchange processes were used for the coagulation of surface water from Meuse river in The Netherlands. The performances of the two purified coagulants and the crude extract were assessed in terms of turbidity and DOC removal. The results indicated that the optimum dosage of the single-step purified coagulant was more than two times higher compared to the two-step purified coagulant in terms of turbidity removal. And the residual DOC in the two-step purified coagulant was lower than in single-step purified coagulant or crude extract.

Dielectric spectra of manganese thiophosphate intercalated with sodium ions

Sodium intercalated manganese thiophosphate Na0.62Mn0.69PS3 powders have been synthesized by a two-step ion-exchange process. Dielectric measurements have been performed as a function of both temperature and frequency on the prepared samples in the 20–106 Hz frequency range over the 78–350 K temperature range by using the autobalancing bridge method. The temperature dependence of the dielectric constant imaginary part reveals the presence of a loss peak at the low temperatures together with a strong dispersion at the low frequencies and at the highest investigated temperatures. While the loss peak presence is characteristic for dipolar polarization processes, the strong low frequency dispersion at not very high temperatures, observed also in the dielectric constant real part, is typical for system with hopping charge carriers. A hypothesis about the nature of such carriers has been formulated on the basis of both the ion-exchange intercalation process and the comparison with the dielectric spectra previously observed for cesium intercalated manganese thiophosphate Cs0.46Mn0.77PS3 compounds.

Hydrocarbon chain conformation in an intercalated surfactant monolayer and bilayer

Cetyl trimethyl ammonium (CTA) ions have been confined within galleries of layered CdPS3 at two different grafting densities. Low grafting densities are obtained on direct intercalation of CTA ions into CdPS3 to give Cd0.93PS3(CTA)0.14. Intercalation occurs with a lattice expansion of 4.8 A with the interlamellar surfactant ion lying flat forming a monolayer. Intercalation at higher grafting densities was effected by a two-step ion-exchange process to give Cd0.83PS3(CTA)0.34, with a lattice expansion of 26.5 A. At higher grafting densities the interlamellar surfactant ions adopt a tilted bilayer structure.13C NMR and orientation-dependent IR vibrational spectroscopy on single crystals have been used to probe the conformation and orientation of the methylene ‘tail’ of the intercalated surfactant in the two phases. In the monolayer phase, the confined methylene chain adopts an essentially all-trans conformation with most of the trans chain aligned parallel to the gallery walls. On lowering the temperature, molecular plane aligns parallel, so that the methylene chain lies flat, rigid and aligned to the confining surface. In the bilayer phase, most bonds in the methylene chain are in trans conformation. It is possible to identify specific conformational sequences containing a gauche bond, in the interior and termini of the intercalated methylene. These high energy conformers disappear on cooling leaving all fifteen methylene units of the intercalated cetyl trimethyl ammonium ion in trans conformational registry at 40 K.

Flaw‐Insensitive Ion‐Exchanged Glass: II, Production and Mechanical Performance

A two‐step ion‐exchange process that introduces strengthening and multiple cracking into glasses has been developed. The experimental parameters in the second step must be carefully controlled to avoid spontaneous cracking, because the compressive stress is reduced in the surface region. Control of the near‐surface stress gradient is an important role of the second ion‐exchange step. Double ion exchange leads to strength values as high as those that are obtained after the first ion‐exchange step but remarkably produces multiple cracking on the specimen surface on loading. The multiple cracking, which acts as a failure warning, is initiated at 300 MPa, and the crack spacing decreases as the applied stress increases. The multiple cracking is shown to be a result of the crack stability that is induced by the designed residual‐stress profiles. This behavior has been confirmed, using the measured residual stresses to calculate the apparent‐toughness curves for surface cracks. The duration of the first ion‐exchange step has been shown to be important in determining the degree of strengthening; however, the duration of the second step controls the extent of the crack stability.

Conformation of Methylene Chains in an Intercalated Surfactant Bilayer

Infrared and Raman spectroscopy have been used to establish the conformation and orientation of the methylene “tail” of cetyl trimethylammonium ions intercalated in an inorganic layered host, $CdPS_{3}$. Intercalation, effected by a two-step ion-exchange process leading to the formation of $Cd_{0.83}$$PS_{3}$ $(CTA)_{0.34}$, occurs with a lattice dilation of 26.5 \AA with the surfactant ions within the galleries adopting a bilayer structure. The frequencies of the conformationally sensitive methylene stretching modes in the infrared and Raman spectra indicate that a majority of the bonds in the methylene chain are in a trans conformation. The methylene chains are tilted with respect to the inorganic layer. The tilt angle as determined from orientation-dependent infrared spectra is \sim $35^0$. Although the population of gauche conformers is low, it has been possible to identify specific conformational sequences containing a gauche bond, in the interior and termini of the intercalated methylene chains, by their characteristic frequencies in the infrared spectrum. These high-energy conformers, except for the ones at the chain end, disappear on cooling, leaving on average all 15 methylene units of the intercalated cetyl trimethylammonium ion in trans conformational registry at 40 K. The terminal gauche defects are significant in preventing interdigitation of the low-density intercalated surfactant bilayer.

Field-assisted ion exchange in glass: The effect of masking films

The two-step ion exchange process for the fabrication of optical waveguide structures in glass is studied. The first step is field-assisted ion exchange through the structure forming ‘‘windows’’ in the masking films. It is established that, in the case of metal masking films, the exchange ability of glass in the region under the mask decreases significantly. The second ion exchange in these regions is even totally blocked when soda-lime glass is used. The mechanism and the application of this effect are briefly considered.