Residual Sodium Ions Research Articles

Synthesis and application of super absorbent polymers synthesized with ammonia solution and diatomaceous earth with low toxic residues

Water-soluble harmful components that remained in SAPs pose potential risks to crop growth, resulting in decreased seed germination rate, reduced yield, and inhibited root system growth. These factors restrict its widespread use in agriculture and forestry. In this study, a new type of super absorbent polymers (AD-SAP) with low residual acrylic acid and sodium ions was synthesized by using ammonia solution instead of strong alkali sodium hydroxide for neutralization and adding modified diatomaceous earth to improve the grafting efficiency. The prepared samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS), and the influence of the dosage of acrylic acid and ammonia solution used for preparation on the residual content of water-soluble harmful components in AD-SAPs was investigated. When 28% of acrylic acid, 24% of ammonia solution, and 5% of diatomaceous earth were used for synthesis, the residual acrylic acid content in AD-SAP was 0.03%, and the sodium ion content was reduced to 0.12 g/kg, which is much lower than the three commercially available SAPs. However, its water-absorption capacity has not decreased and its salt resistance has improved. The water absorption ratio of AD-SAP is 578g/g, and the salt-absorption ratio is 87 g/g. Pot experiments showed that AD-SAP eliminated the adverse effects of commercial SAPs on crop growth. The research provided technical support for the production of SAPs, and offer scientific guidance for how to mitigate the adverse effects of SAPs on crop growth.

Toward the efficient direct regeneration of spent cathode materials through the effect of residual sodium ions analysis

Recycling spent lithium-ion batteries is an important means for promoting sustainability within the energy industry. In this study, the effects of residual sodium on the regeneration process and the performance of spent LiNi0.5Co0.2Mn0.3O2 were explored. An appropriate amount of residual sodium was found to improve the properties of the regenerated material, with the best cycle performance and rate performance at a residual sodium of 3 mol %. The first-cycle and 100-cycle discharge capacities were 136.4 mA h g−1 and 120 mA h g−1, respectively, with a capacity retention rate of 87.98% after 100 cycles at a rate of 1 C. The electrochemical performance of the regenerated cathode materials was improved because sodium occupied the lithium sites in the crystal structure, providing a channel for lithium deintercalation. These results indicate that the residual sodium ions should be monitored in appropriate quantities to improve the efficiency of recycling spent lithium-ion batteries.

Surface physicochemical characteristics for sodium ion removal with sodium silicate modified magnetite core-shell nanoparticles and activation of their plasmid DNA purification ability

In this study, it is investigated the elimination of residual sodium ions from sodium silicate (Na2SiO3) modified Fe3O4@SiO2 nanoparticles, via the additional acidic treatment. Residual sodium ions are generated from the Na2SiO3 precursor during the titration for the fabrication of the Fe3O4@SiO2 core-shell structure; however, they were entirely removed after the in situ additional titration at pH 3 using a 1 M of hydrochloric acid (HCl). The thickness of the SiO2 shell layer of each nanoparticle was measured to 10 nm and the morphology of SiO2 shell on the Fe3O4 core were not significantly different after acid treatment to remove the residual sodium ions. However, the absolute zeta potential of the Na2SiO3-modified Fe3O4@SiO2 was decreased about 20% after HCl treatment (−52.5 ± 3.0 mV). In addition, the mean particle size of the Na2SiO3-modified Fe3O4@SiO2 was increased (363.98 nm) and the polydispersity index, which indicates dispersibility was increased (0.23) since residual sodium ions were eliminated by the acid treatment. It is assumed that the reducing anions in the diffuse layer of the particle due to the elimination of the residual sodium, as the counter ion, decreased the surface charge, thereby reducing the repulsive force between the Fe3O4@SiO2 nanoparticles. Then Fe3O4@SiO2 nanoparticles were utilized for separating plasmid DNA and separated plasmid DNA was measured with agarose gel electrophoresis and the absorbance monitoring. The efficiency of the DNA purification of the Na2SiO3-modified Fe3O4@SiO2 measured to 43.3 ± 5.2 ng/μl which was 58% increased after acid treatment. As a result, the dispersion/magnetic properties and DNA purification efficiency of the Na2SiO3-modified Fe3O4 became equivalent to the characteristics of the TEOS-modified Fe3O4@SiO2 using the additional acid treatment for sodium ions removal.

Enhanced thermal stability of hierarchical Y zeolites obtained by acid and subsequent base treatments

Ion exchange and thermal stability of hierarchical Y zeolites obtained by the acid and subsequent base treatments of commercial NaY zeolite were studied. It was found that the resulting hierarchical Y zeolite exhibited lower lanthanum ion exchange efficiency and thermal stability compared to the parent NaY zeolite. The introduction of lanthanum in the hierarchical Y zeolite significantly enhanced its thermal stability due to the advantageous combination of the stabilized effect of lanthanum and the reduced content of residual sodium ions. The latter was of paramount importance because the presence of sodium ions promoted breakdown of the hierarchical Y zeolite framework by dislodging aluminum enriched on the zeolite surface during the base treatment. Notably, the generated mesopores facilitated removal of residual sodium ions during the ammonium ion exchange treatment. Consequently, the hierarchical Y zeolite displayed superior thermal/hydrothermal stability even with a low La loading of 3 w t.%.

A Self-Ion Exchange of Na0.53 MnO2+ Cathode for Li+/Na+ Hybrid Ion Battery

P2-structure sodium manganese oxide is synthesized by a simple reduction reaction. The low-cost electrodes of lithium / sodium hybrid ion batteries after the ion exchange process provide new data on the direct use of sodium manganese oxide instead of lithium analogue. As observed by X-ray diffraction analysis, ion exchange occurs in sodium manganese oxide through electrolytes during cell stabilization. Its own ion exchange material has a high discharge capacity of 195 mA h g-1and a stable plateau at 3.0 V for 50 cycles. In-situ X-ray diffraction and ex-situ X-ray absorption close to edge structure studies confirm reversible oxidation reduction reactions and stable structural changes. ex-situ induced coupled plasma atomic emission spectroscopy confirms that residual sodium ions act as pillars during cycling in the structure.

Structural stability of metal containing ferrierite under the conditions of HT-N2O decomposition

Abstract Ferrierite based catalyst is expected to be used for high-temperature decomposition of N2O. The stability of the ferrierite structure and divalent cations in ferrierite in this process were analysed using XRD, SEM, FTIR, 27Al and 29 Si MAS NMR. This study provides detailed information regarding to Al removal from zeolite that is either involved in the Bronsted acid sites or formation of local cationic sites responsible for bonding divalent cations. The Al atoms, which stabilize divalent cations in cationic positions, have the potential to be resistant to prolonged exposure to the conditions of high-temperature decomposition of N2O. The presence of water led to the destruction of the iron active sites for N2O decomposition in iron ferrierite. Moreover, the negative role of residual sodium ions eventually remaining in the commercial ferrierite was proven to induce the irreversible collapse of the zeolite framework.

Formation of Supramolecular Clusters at the Interface of Zeolite X Following the Adsorption of Rare-Earth Cations and Their Impact on the Macroscopic Properties of the Zeolite.

The adsorption behavior of neodymium (Nd3+ ) and yttrium (Y3+ ) cations on synthetic FAU zeolite X in its sodium form (NaX) has been investigated by means of macroscopic (adsorption isotherm determination and thermal analysis) and microscopic measurements (including solid-state NMR spectroscopy and X-ray powder diffraction). The multidisciplinary study reveals some unexpected features. Firstly, adsorption constants of cations are not correlated to their ionic radii or hydration enthalpy. The adsorption constant of Y3+ on NaX was indeed about twice that of Nd3+ , which is the opposite of what could be expected based on the size of the cations. In addition, adsorption was accompanied by partial dealumination of the zeolite framework. The extent of dealumination changed depending on the exchanged cations, with the extent being more significant on the Nd-exchanged zeolite than on the Y-exchanged one. The most interesting finding of this study, however, is the presence of supramolecular clusters composed of water, Nd3+ , residual sodium ions, and extra-framework aluminum at the interface of Nd-exchanged zeolite. The hypothesis that these host-guest complexes are responsible of the significantly different behavior exhibited by NaX towards the adsorption/desorption of Nd3+ and Y3+ has been formulated.

Effect of precipitants on the catalytic performance of Pd–Cu/attapulgite clay catalyst for CO oxidation at room temperature and in humid circumstances

The Pd–Cu/attapulgite clay catalysts were synthesized using a deposition–precipitation method with different precipitants. The as-synthesized catalysts were characterized by ICP-AES, N2-physisorption, XRD, FT-IR, TEM and TPR. Their catalytic activities for CO oxidation were tested by a fixed-bed continuous flow reactor at room temperature and in humid circumstances. The results illustrated that the activity of CO oxidation strongly depended on the precipitant. The best catalytic performance is achieved by using NH3·H2O (PC-AH) or NH4HCO3 (PC-AHC) as precipitants. The crystalline phase of PC-AH and PC-AHC comprised of Cu2Cl(OH)3 and CuO, while the catalysts prepared with NaOH (PC-SH) or NaHCO3 (PC-SHC) as precipitants were mainly CuO. Combined with FT-IR and TEM results, it could be found that Cu2Cl(OH)3 on PC-AH and PC-AHC possessed higher stability than that on PC-SH and PC-SHC due to the different formation process and morphology of Cu2Cl(OH)3 species. The TPR results showed that the Cu2Cl(OH)3 had a strong interaction with Pd species and enhanced reducibility. Moreover, the residual sodium ions on PC-SH and PC-SHC may have adverse effect on the catalytic activity. A suitable precipitant resulted in the most efficient CO oxidation catalyst at room temperature and in humid circumstances.

Identification of the Basic Sites on Nitrogen-Substituted Microporous and Mesoporous Silicate Frameworks Using CO2 as a Probe Molecule.

Carbon dioxide was shown to identify surface basic properties of nitrogen-substituted microporous and mesoporous silicas, in addition to conventional basic oxides, by a detailed study using isotherm and heat of adsorption measurements as well as by infrared spectroscopy. A hydrogen-bonded weak interaction was primarily observed between CO2 and silanol (Si-OH) and silamine (Si-NH-Si) groups. The heat of adsorption of CO2 demonstrated that the latter adspecies were formed preferentially over the former, although a much higher amount of linear CO2 adspecies were found on SBA-15 mesoporous silica because of the presence of a large quantity of silanol groups on its surface. Carbamate-type chemisorbed adspecies were not detected on silamino sites, whereas carbonate-type adspecies were formed on alkali ion-exchanged zeolites and also residual sodium ions on the surface of silicalite-1. CO2 was shown to be a successful probe molecule for identifying weakly interactive hydrogen-bonding sites, and it has potential as a surface probe for strongly interactive nucleophilic sites derived from alkaline ions or a methylated silamino group, Si-N(CH3)-Si.

Influence of residual sodium ions on the structureand properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate).

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a promising conducting polymer in terms of its applicability to transparent and flexible electronic devices. Generally, a negatively charged PSS chain can interact with alkali metal cations like sodium and potassium. During polymerization, these ions, especially sodium ions, remain in an aqueous state and affect particle formation. This paper describes the effect of residual sodium ions on the synthesis of PEDOT:PSS and its electrical and optical properties. Removing the sodium ions weakens the coulombic interaction between the PEDOT and PSS chains, which leads to a linear conformation. This conformational change enhances the electrical conductivity and work function. Furthermore, transmittance in the visible region increased remarkably because the intrinsic electrical properties of the PEDOT:PSS particles were improved. Moreover, the colloidal stability was enhanced because the particle coagulation caused by residual sodium ions was reduced. In summary, we determined that sodium ions in PEDOT:PSS have a considerable influence on its electrical and optical properties and colloidal stability for practical applications.

Sodium manganese oxide electrodes accompanying self-ion exchange for lithium/sodium hybrid ion batteries

P2-structure sodium manganese oxide is synthesized by a facile reduction reaction. We provide new data on the direct use of sodium manganese oxide instead of lithium analogues as a low-cost electrode for lithium/sodium hybrid ion batteries after an ion-exchange process. Ion exchange occurs in sodium manganese oxide through the electrolyte during cell stabilization, as observed by X-ray diffraction analysis. The self ion-exchanged material delivers a high discharge capacity of 195 mA h g−1 and a stable plateau at 3.0 V for 50 cycles with stable cyclability. In-situ X-ray diffraction and ex-situ X-ray absorption near edge structure studies also confirm reversible redox reactions and stable structural changes. The ex-situ inductively coupled plasma atomic emission spectroscopy analysis verifies that residual sodium ions in the structure act as pillars during cycling.

Self-Functionalization Behind a Solution-Processed NiOx Film Used As Hole Transporting Layer for Efficient Perovskite Solar Cells.

Fabrication of solution-processed perovskite solar cells (PSCs) requires the deposition of high quality films from precursor inks. Frequently, buffer layers of PSCs are formed from dispersions of metal oxide nanoparticles (NPs). Therefore, the development of trustable methods for the preparation of stable colloidal NPs dispersions is crucial. In this work, a novel approach to form very compact semiconducting buffer layers with suitable optoelectronic properties is presented through a self-functionalization process of the nanocrystalline particles by their own amorphous phase and without adding any other inorganic or organic functionalization component or surfactant. Such interconnecting amorphous phase composed by residual nitrate, hydroxide, and sodium ions, proved to be fundamental to reach stable colloidal dispersions and contribute to assemble the separate crystalline nickel oxide NPs in the final film, resulting in a very homogeneous and compact layer. A proposed mechanism behind the great stabilization of the nanoparticles is exposed. At the end, the self-functionalized nickel oxide layer exhibited high optoelectronic properties enabling perovskite p-i-n solar cells as efficient as 16.6% demonstrating the pertinence of the presented strategy to obtain high quality buffer layers processed in solution at room temperature.

Ion-exchange mechanism of layered transition-metal oxides: case study of LiNi(0.5)Mn(0.5)O₂.

An ion-exchange process can be an effective route to synthesize new quasi-equilibrium phases with a desired crystal structure. Important layered-type battery materials, such as LiMnO2 and LiNi(0.5)Mn(0.5)O2, can be obtained through this method from a sodium-containing parent structure, and they often show electrochemical properties remarkably distinct from those of their solid-state synthesized equivalents. However, while ion exchange is generally believed to occur via a simple topotactic reaction, the detailed phase transformation mechanism during the process is not yet fully understood. For the case of layered LiNi(0.5)Mn(0.5)O2, we show through ex situ X-ray diffraction (XRD) that the ion-exchange process consists of several sequential phase transformations. By a study of the intermediate phase, it is shown that the residual sodium ions in the final structure may greatly affect the electrochemical (de)lithiation mechanism.

Hydrothermal synthesis and optical properties of hexagonal tungsten oxide nanocrystals assisted by ammonium tartrate

AbstractCrystals of hexagonal tungsten oxides (hex‐WO3) have been synthesized using hydrothermal method at 150 °C, assisted by the capping reagent of ammonium tartrate (AT). The XRD and EDX results reveal that the lattice distortion exists in all the samples, possibly due to the defects and the intercalation of the residual sodium ions. Different crystal shapes including plate‐like, urchin‐like, and particle structures were obtained by varying concentration of AT and pH values in the precursor solution. Beside the absorption action of the ${\rm NH}_{4}^{ + } $ and Na+ ions, the capping effect can be reinforced by the hydrogen bonding from the tartrate groups in the crystallization process. The bandgap energies were modulated by the size of the nanostructured hex‐WO3 crystals due to quantum confinement effect, which increases from 2.74 to 3.04 eV. Based on the analysis of the photoluminescence and X‐ray photoelectron spectroscopy, the enhancement of the blue emission of the nanocrystals is assigned as a result of a complex of the local intercalation of the residual sodium ions and the oxygen vacancies or defects.

Cyclopropane Adsorption on Zeolites Studied by IR Spectroscopy: II. Adsorption and Conversion of Cyclopropane on Na- and Ca-Exchanged Zeolite Y

The adsorption and isomerization of cyclopropane on the calcium- and sodium-exchanged zeolite Y are studied by IR spectroscopy. Cyclopropane is adsorbed on CaY in two different forms. Weaker adsorption is related to residual sodium ions, which were not completely removed from the zeolite by ion exchange. This form can be removed from the surface after evacuation of the samples at room temperature. Stronger adsorption is attributed to the Ca ions. It is stable up to 100°C. The corresponding diffuse-reflectance spectrum indicates the C 2v symmetry of the cyclopropane complex with Ca ions. At 200°C cyclopropane adsorbed on the calcium-exchanged zeolite converts to propylene. On the sodium-exchanged zeolite, this reaction only occurs at 400°C. The reaction coordinate of cyclopropane isomerization on CaY is related to the simultaneous cleavage of the C–C bond in the cyclopropane ring and hydrogen atom transfer from one of the CH2 fragments to another. The reaction coordinate corresponds to a combination of the stretching vibration of the C–C bond with the fan vibration of the CH2 group and the stretching vibration of the CH bond. These composite vibrations result in the strong polarization of the C–C and C–H bonds and, hence, exhibit anomalously high molar absorption coefficients in the IR spectrum.

Adsorption of Dimeric (Gemini) Surfactants at the Aqueous Solution/Silica Interface

The adsorption on silica of four alkanediyl-α,ω-bis(dodecyldimethylammonium bromide) dimeric surfactants with the alkanediyl spacer groups C2H4, C4H8, C6H12, and C10H20(the corresponding surfactants are referred to as 12–2–12, 12–4–12, 12–6–12, and 12–10–12, respectively), has been investigated by measuring the amount of surfactant adsorbed, the sodium and bromide ion concentrations in the supernatant solution along the binding isotherm, and the electrophoretic mobility of the silica particles. The maximum amount of adsorbed surfactant was found to increase in the sequence 12–10–12 < 12–6–12 < 12–4–12 < 12–2–12. In the range of very low equilibrium concentration the adsorption isotherms showed a rapid but small increase of the amount of adsorbed surfactant, Γ, followed by an adsorption plateau corresponding to a Γ value that was nearly independent of the spacer carbon number,s. The point of zero charge was reached at the beginning of this plateau. In this first adsorption step, the residual sodium ions present at the silica surface are released upon binding of dimeric surfactant ions to the silica surface (exchange process). The length of the adsorption plateau depends strongly on the nature of the surfactant, being the shorter for the most hydrophobic surfactant, i.e., 12–10–12. At the end of the first adsorption plateau the value of Γ shows a second very rapid increase when plotted against the concentration of free surfactant. This increase is accompanied by a decrease of the supernatant pH, from 6.5 to about 4.0, and an increase of the concentration ratio [free bromide ion]/[free surfactant ion]. This second adsorption step corresponds to the formation of surfactant aggregates at the silica surface. Part of the bromide ions are shown to be bound to these aggregates which are, however, more ionized than the free micelles formed by the dimeric surfactants investigated.

The effects of ionization and epoxy reaction on the surface and mechanical properties of poly( p-phenylene terephthalamide) fibres

The effects of ionization and epoxy reactions on the bulk and surface properties of poly( p-phenylene terphthalamide) (PPTA), namely Kevlar 149, fibres were studied. When the ionized Kevlar 149 fibres were quenched in water, their tensile properties were significantly lowered with increasing ionization time. The lowered tensile strengths were attributed to the reactions between the residual sodium ions in the fibres and water, and possibly the subsequent hydrolytic chain scissions of the PPTA molecules. The tensile properties of the fibres were only slightly lowered with increasing NaH concentrations. With increasing ionization time, the epoxy reaction first significantly lowered and then began to compensate for the tensile properties of the fibres. The interfacial shear strength of the Kevlar 149 fibres with the epoxy was slightly higher and was associated with better wetting property of Kevlar 149 fibres and surface compositional differences between the two PPTA fibres. The ionization and epoxy reaction conditions employed for Kevlar 49 fibres did not affect the interfacial shear strengths with the epoxy resin. The interfacial shear strength for Kevlar 149 fibres was increased from 4.35 × 10 −3 g μm −2 for the untreated to 5.29 × 10 −3 g μm −2 for the ionized and epoxy-reacted fibres, a 22% increase.

Site-selective excitation of Eu3+ substituted sodium β″ alumina single crystals

Broad band excitation spectra of Eu3+ substituted sodium β″ alumina reveals that the Eu3+ ions occupy at least two distinct sites. Examination of the fluorescence spectrum excited by an ultraviolet laser (308 nm) reveals the presence of an additional site. 5D0→7FJ emission spectra characteristic of each site were obtained using site-selective excitation. A crystal-field analysis of the emission spectra thus obtained permits the assignment of these sites. The two inhomogeneously broadened 5D0→7F0 emissions at 569.4 and 576.7 nm are assigned as mid oxygen sites perturbed by various arrangements of the residual sodium ions, while the sharp 5D0→7F0 emission at 578.7 nm is assigned as the Beevers–Ross site.

Structure of Phosphate lons in Magnesium Highpolyphosphate Coacervate and lts Dehydration Products

Magnesium highpolyphosphate coacervates were prepared by a reaction bet. ween cationexchanged aqueous solution of sodium metaphesphate and magnesium chloride solgtion.Molar ratios of MgO/P2O5 in coacervates were distributed in the vicinity of O.8. The deviation of their ratios from the theoretical value 1.0 could be attributed to the coexistence of sodium ions. A paper chromatography test showed that at least 850% of phospsphate ions in the coacervates were in a highly polymerized from (n 8) and the rest were in a ortho form. A number average polymerization degree of the highpolyphosphate ions was determined to be 25-50 by an acid base titration.Small amounts of the residual sodium ions brought about the formation of crystalline substance X besides mat gnesium tetrametaphosphate, both were the final products of a successive condensation reaction caused by the heat-treatment of the samples. On the other hand, a condensation process of a sodium-free coacervate coincided precisely with that of Mg(H2PO)2 2H2O. The appearance of characteristic PO2 and PO3 peaks in IR and Raman spectra suggested that substance X was a linear sodium magnesium polyphosphate with comparatively short chain length. Furthermore, X was proved to be disodium trimagnesium hexapolyphosphate (Mg3Na2P6O19) by a fact that only a substance having the composition of 3MgO Na2O 3P2O5 gave the same X-ray diffraction pattern as that of X.

Quantitative infrared spectroscopy of amines in synthetic zeolites X and Y: II. Adsorption of amines on Na-hydrogen zeolites X and Y

Different amines have been adsorbed on Na-hydrogen zeolites X and Y. The decrease of the OH stretching bands of the zeolites and the formation of ∂NH + bands of the alkyl-ammonium ions have been followed quantitatively. The adsorption involves the following mechanisms: (i) reaction with the acidic hydroxyls, (ii) coordination to residual sodium ions, (iii) adsorption on dehydroxylated sites. The adsorption of amines has a dehydroxylating effect which is especially pronounced for pyridine.