Influence Of Ion Exchange Research Articles

Investigation of the Structure and Influence of Ion-Exchange on the Microhardness of Low-Alkali, Transparent, Gahnite-Based Glass-Ceramics

Investigation of the Structure and Influence of Ion-Exchange on the Microhardness of Low-Alkali, Transparent, Gahnite-Based Glass-Ceramics

Influence of Ion Exchange on Photoresponsive Properties of Potassium Poly(heptazine imide)

Metal poly(heptazine imide) (MPHI) exhibits various optoelectronic functions by accommodating various metal ions in its heptazine-based graphite-like two-dimensional layer. Although potassium PHI (KPHI) is the most well-studied in MPHI series, there are unresolved issues regarding the mechanism responsible for its unique properties, particularly its high photocatalytic activity. The mechanisms underlying other diverse properties, such as photochromism and photoconduction, also remain unknown. Herein, we focused on elucidating the mechanisms of photochromism and photoconduction in KPHI. We developed a method to gradually replace K+ in KPHI with H+ and successfully prepare samples with tunable K+ concentrations. The structural, chemical, optical, electronic, and electrical properties of samples with continuously varying K+ concentrations were thoroughly investigated through various experiments and theoretical calculations. First, the gradual substitution of K+ for H+ in KPHI was investigated using X-ray photoelectron spectroscopy, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy. XRD analysis revealed that K+ in KPHI was not randomly substituted with H+, but even small amounts of K+ substitution led to the formation of the long-range ordered region of HPHI. Absorbance measurements revealed a continuous blue shift of the absorption edge as the ratio of K+ decreased from that of KPHI. Energy band calculations revealed that the energy gap of HPHI was more than 14% larger than that of KPHI. The dependence of the K+ concentration measurements on the photochromism and photoconductive properties showed that in the K+-rich samples, the K+ released from the PHI layer upon white light irradiation had a significant effect on the electrical conduction properties. K+ conduction was dominant in the electrical conduction of KPHI, including photoconduction, under ambient conditions. However, the mobility of H+ in HPHI was very low, which was responsible for the lethargic return to the ground state after photoexcitation and minimal electrical conductivity.

Efficiency enhancement with chloride to iodide ion exchange of benzimidazolium salt as a redox mediator.

The new benzimidazolium derivative (SM-1) salt with ion exchange from the (SM-0) was fabricated and characterized by proton-nuclear magnetic resonance (1H-NMR), carbon-nuclear magnetic resonance (13C-NMR), Fourier-transform infrared spectroscopy (FT-IR), electrospray ionization (EIS-MS), thermal analysis (TG), cyclic voltammetry (CV), and ultraviolet-visible spectroscopy (UV-vis), for electrolytes (liquid or dried) in the DSSC charge transportation mechanism. Also, the influence of ion exchange from chloride to iodine in the synthesized electrolytes, compared to other electrolytes (conventional or commercial), was investigated about DSSC performance efficiency. When using as a liquid electrolyte (SM-1), the power conversion efficiency (ƞ) of the working DSSC device was recorded as 1.980% and it was observed that the performances of DSSCs increased up to 56% when comparing dried electrolyte for SM-1 without conventional redox material (I-/I3-). In the future, different molecular modifications of this type of benzimidazole derivatives or mixtures with conventional redox couples may further improve the performance of DSSC devices.

The influence of ion exchange in zeolite X on the properties of phenol-formaldehyde composites

This work focused on the influence of ion exchange in the zeolite X structure on the properties of composites with phenol-formaldehyde resin. Four types of zeolites X with mono and divalent cations were prepared and used as fillers in phenolic composites. The results obtained using energy dispersive spectrometry confirm the effectiveness of ion exchange. Analysis of materials with several techniques indicates no differences between individual zeolites. The influence of ion exchange is visible only in the parameters determined by inverse gas chromatography. The ability for dispersive and acid-base interactions described by these parameters is significantly different for zeolites with monovalent cations than divalent cations: generally, zeolites with monovalent cations are characterized by more active surfaces and higher acidity. The material with the highest flexural strength was the composite with the sodium form of zeolite. The influence of cation type on cross-linking and thermal stability of phenolic composites was also noted.

Catalytic performance of nanostructured Pt/ZSM-5 catalysts synthesized by extended Charnell’s method in hydroisomerization of n-pentane

Na-ZSM-5 zeolite, synthesized by extended Charnell’s method was used to prepare Pt/ZSM-5 catalyst for n-pentane hydroisomerization. The influence of ion exchange, alkaline treatment and method of platinum incorporation on the Na-ZSM-5 zeolite was investigated. It was found that the presence of Trien affected the physicochemical properties of the synthesized catalyst. The synthesized catalysts showed high performance so that the sample prepared in rotating mode at 24 h and Pt loaded via impregnation showed conversion and selectivity about 75 and 97%, respectively. Also, a maximum yield for this catalyst was achieved at 250 °C.

ABS/Nonexpandable muscovite clay nanocomposites: The effect of ion exchange on dispersion of nanofillers and flexural properties

In this work, acrylonitrile‐butadiene‐styrene (ABS)‐based nanocomposites with different muscovite concentrations (1–5 wt%) treated by ion exchange process were prepared by melt compounding. The influence of ion exchange and muscovite amount on the morphological, structural, and flexural properties was examined using wide‐angle X‐ray diffraction (WAXD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), and three‐point bending test. The modified muscovite significantly enhanced basal spacing and CTA+ molecules successfully intercalated into the gallery of muscovite. The morphology indicated that organomuscovite (OM) dispersed well in ABS resin and the intercalated‐exfoliated structures of ABS nanocomposites were, respectively, formed. Conversely, contact angle measurements revealed that increasing OM loading would increase the hydrophobicity of ABS nanocomposites. The flexural properties showed that the flexural strength and modulus were improved by 10% and 28%, respectively, in comparison to neat ABS. POLYM. COMPOS., 40:3562–3572, 2019. © 2019 Society of Plastics Engineers

Synthesis of NaX and NaY Zeolites from Tunisian Kaolinite as Base Catalysts: An Investigation of Knoevenagel Condensation

AbstractThe synthesis of Faujasite‐type zeolites with high purity has been successfully performed from Tunisian kaolinite and the effects of different crystallization parameters on the final products were widely investigated. The alkaline fusion of kaolinite followed by hydrothermal treatment lead to zeolite NaX synthesis whereas the classic hydrothermal transformation of metakaolinite produces NaY zeolite. The results show that an increase in the synthesis temperature and time has improved the crystallization process of the zeolite NaX whereas the SiO2/Al2O3 and the Na2O/SiO2 molar ratios were the key parameters to obtain a pure zeolite NaY. The highest specific surface areas obtained with the optimal crystallization conditions were 554 m2 g−1 and 592 m2 g−1 for respectively NaX and NaY zeolites. The basic properties of NaX and NaY zeolites were explored in the Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate at 140 °C as a test reaction in the absence of solvent. The influence of ion exchange with cesium cation on the catalytic activity of prepared catalysts was also investigated. It was found that the NaX provided higher activity than that of NaY catalyst due to its lower Si/Al ratio whereas a cesium exchange conferred higher basicity to the prepared Na‐faujasite.

First-principles elasticity of monocarboaluminate hydrates

The elasticity of monocarboaluminate hydrates, 3CaO·Al2O3·CaCO3·xH2O (x = 11 or 8), has been investigated by first-principles calculations. Previous experimental study revealed that the fully hydrated monocarboaluminate (x = 11) exhibits exceptionally low compressibility compared to other reported calcium aluminate hydrates. This stiff hydration product can contribute to the strength of concrete made with Portland cements containing calcium carbonates. In this study, full elastic tensors and mechanical properties of the crystal structures with different water contents (x = 11 or 8) are computed by firstprinciples methods based on density functional theory. The results indicate that the compressibility of monocarboaluminate is highly dependent on the water content in the interlayer region. The structure also becomes more isotropic with the addition of water molecules in this region. Since the monocarboaluminate is a key hydration product of limestone added cement, elasticity of the crystal is important to understand its mechanical impact on concrete. Besides, it is put forth that this theoretical calculation will be useful in predicting the elastic properties of other complex cementitous materials and the influence of ion exchange on compressibility.

Influence of ion-exchange on the electrochemical properties of polypyrrole films

Cyclic voltammetry, X-ray microanalysis (EDS), FTIR, and AFM were applied for the systematic examination of the influence of self-exchange and potential stimulated ion-exchange on the electrochemical properties of polypyrrole (PPy) films prepared in the presence of benzene sulfonate (BS), para-toluene sulfonate (pTS), and naphthalene-1, 5-disulfonate (NDS) anions. All electrochemical experiments were carried out in aqueous solutions. It was established that small inorganic anions, like NO3−, Cl−, ClO4− can relatively easily replace an essential part of the sulfonates in PPy/BS and PPy/pTS films simply during a 10min polarization at 0.4V. A single potentiodynamic cycle increases the completeness of the exchange of the anions remarkably. The EDS analysis carried out before and after the anion exchange showed that 5–15% of the sulfonate anions still remain in the PPy films. The ability of the double-charged SO42− anions to replace sulfonate anions is even more pronounced as the exchange process does not need additional electrochemical activation. The quantum chemical model calculations have shown that the interaction of the sulfate anions with charged pyrrole oligomers is essentially stronger compared to other anions under the study.The redox capacitance and the corresponding electrochemical doping level of the redoped PPy films are remarkably higher than those before ion-exchange, showing that the PPy matrix formed in the presence of sulfonate anions does not collapse after ion-exchange and it creates favorable conditions for increased mobility of inorganic anions.

Bioavailability of Barium to Plants and Invertebrates in Soils Contaminated by Barite

Barium (Ba) is a nonessential element to terrestrial organisms and is known to be toxic at elevated concentrations. In this study, the bioavailability and toxicity of Ba in barite (BaSO4) contaminated soils was studied using standard test organisms (Lactuca sativa L. "Great Lakes", Eisenia fetida). Contamination resulted from barite mining activities. Barium concentrations in contaminated soils determined by X-ray fluorescence were in the range 0.13-29.2%. Barite contaminated soils were shown to negatively impact both E. fetida and L. sativa relative to control soil. For E. fetida, pore-water concentrations and acid extractable Ba were linearly related to % body weight loss. In L. sativa, pore-water Ba and exchangeable Ba were both strongly related to shoot Ba and shoot biomass production. A negative linear relationship was observed between shoot Ba content and shoot weight (P < 0.0004, R(2) = 0.39), indicating that Ba accumulation is likely to have induced phytotoxicity. Plant weights were correlated to % weight loss in earthworm (r = -0.568, P = 0.028). Barium concentrations in pore-water were lower than predicted from barite solubility estimates but strongly related to exchangeable Ba, indicating an influence of ion exchange on Ba solubility and toxicity to E. fetida and L. sativa.

Mathematical analysis of human red blood cell volume regulation with regard to the elastic effect of the erythrocyte shell on metabolic processes

The mathematical model of the regulation of ion exchange and human erythrocyte volume is extended with a biomechanical model of the erythrocyte shell. This model was used to analyze the influence of elastic properties of the erythrocyte shell on erythrocyte volume in the experiments, where the volume of erythrocytes increased due to the formation of ion channels in the membrane after the treatment with amphotericin B and in case of placing red blood cells in a hypo-osmotic medium. During red blood cell deformation at a constant surface area up to sphericity, the influence of mechanical properties of the shell on volume regulation was shown to be negligible compared to the influence of ion exchange. Further osmotic swelling of red blood cells followed by the increase in their surface area is determined by tensile stiffness of the shell. The high value of tensile stiffness inherent to the erythrocyte shell is constraint for its volume change and also affects ion exchange.

Lix(Mn1 − yCoy)O2 intercalation compounds as electrodes for lithium batteries: influence of ion exchange on structure and performance

Download options Please wait... Article information DOI https://doi.org/10.1039/B002948N Article type Paper Submitted 18 Apr 2000 Accepted 07 Jul 2000 First published 06 Oct 2000 Download Citation J. Mater. Chem., 2001,11, 113-118 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Lix(Mn1 − yCoy)O2 intercalation compounds as electrodes for lithium batteries: influence of ion exchange on structure and performance A. D. Robertson, A. R. Armstrong, A. J. Fowkes and P. G. Bruce, J. Mater. Chem., 2001, 11, 113 DOI: 10.1039/B002948N To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Alastair D. Robertson A. Robert Armstrong Amelia J. Fowkes Peter G. Bruce

Investigations on the behaviour of acidic, basic and neutral compounds in capillary electrochromatography on a mixed-mode stationary phase

This work describes the separation of acidic, basic and neutral organic compounds as well as inorganic anions in a single run by capillary electrochromatography employing a stationary phase which exhibits both strong anion-exchange and reversed-phase chromatographic characteristics. The positive surface charge of this stationary phase provided a substantial anodic electroosmotic flow. The analytes were separated by a mixed-mode mechanism which comprised chromatographic interactions (hydrophobic interactions, ion-exchange) as well as electrophoretic migration. The influence of ion-exchange and hydrophobic interactions on the retention/migration of the analytes could be manipulated by varying the concentration of a competing ion and/or the amount of organic modifier present in the background electrolyte. Additionally the effects of pH changes on both the chromatographic interactions as well as the electrophoretic migration of the analytes were investigated.

Behavior of basic compounds in ion-exchange capillary electrochromatography with low-pH carrier electrolytes

This work describes the separation of basic aromatic compounds by capillary electrochromatography employing acidic carrier electrolytes and bare silica as well as strong cation-exchange stationary phases. A mixed-mode separation mechanism was involved, comprising chromatographic interactions (adsorption, ion-exchange) as well as electrophoretic migration. The influence of ion-exchange on the retention/migration of the solutes could be manipulated according to procedures commonly employed in ion chromatography. These include variations of the eluting strength and/or the concentration of the competing ion present in the background electrolyte. Using this approach, separation times could be shortened and changes in selectivity could be achieved for a number of analytes.

Influence of ion exchange on liquid–liquid phase separation in alkali borosilicate glasses: effect of ion-exchange-induced metastable glass homogenization

Experimental results of studying the metastable liquid–liquid phase separation and homogenization induced by ion exchange in (15- x)Li 2O · xNa 2O · 35B 2O 3 · 50SiO 2 glass-forming system are presented. Both a homogeneous under-surface layer in a phase-separated glass and a phase-separated under-surface layer in a homogeneous glass have been formed by an ion exchange technique. The Li-for-Na ion exchange in the glass with x=15 led to phase-separated layers while the Na-for-Li ion exchange in the phase-separated glass with x=5 led to the homogeneous vitreous layers. These effects and the conditions that produce them are discussed from the viewpoint of phase equilibria in the system involved.

ChemInform Abstract: Influence of Ion Exchange and Calcination on Pore Size and Thermal Stability of MCM‐41 with Different Si/Al Ratios.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Raman and X-ray absorption study of selenium incorporated into the channels of mordenite: Dependence on the ion exchange and the method of incorporation

Influence of ion exchange and method of selenium incorporation into mordenite channels on the structure of incorporated selenium species are studied by Raman and X-ray absorption spectroscopy. It is shown that Se chains prepared by Se vapor adsorption are more regular than Se chains prepared by pressure injection of liquid Se. Concentration ratio between Se chains and Se 6 rings is found to be practically independent of the method of preparation but dependent on the type of cations in mordenite channels. Substitution of Na cations by larger monovalent cations leads to a decrease in Se chains concentration compared to Se 6 rings concentration and to an increase in average SeSe bond length. X-ray absorption spectrum of M-Se for polarization of radiation perpendicular to the channels is shown to be determined mainly by Se6 rings, and that for polarization parallel to the channels is a superposition of the absorption of chains and rings. Selenium incorporated into H-form of mordenite is found to be located not only in the original mordenite channels, but also in meso-channels organized due to partial destruction of the interchannel walls.

Influence of ion exchange and calcination on pore size and thermal stability of MCM-41 with different Si/Al ratios

A decrease in pore size and increase in thermal stability of three different MCM-41 materials with Si/Al ratios of 18.6, 17.3 and 3.1, due to ammonia ion exchange and following calcination at 540°C, has been observed by N2 sorption measurements, differential thermal analysis (DTA) and X-ray diffraction (XRD). An explanation based on recrystallization at the pore mouth is proposed and the influence of the alumina content of the materials is discussed.

Dealumination of zeolite L with SiCl4: influence of ion exchange

The dealumination of zeolite L with SiCl4 is made feasible through its exchange into the sodium form; a higher degree of framework dealumination than previously reported, for any dealumination method, is achieved.

Influence of ion exchange on dissolved load of alpine meltwaters

AbstractMeltwaters were collected in Switzerland at the border of two alpine glaciers, the Tsanfleuron glacier resting on limestones and the Tsijiore Nouve glacier flowing over gneissic rocks. Waters were analysed by atomic absorption spectrophotometry for the four major cations.Cation exchange appears to be an essential mechanism in the explanation of the dissolved cationic content of meltwaters in the frontal zone of glaciers. This is indicated by a study of the rate and characteristics of water enrichment.The rate‐determining step in the process seems to be film diffusion. The influence of this diffusion is put forward in an analysis of the rates of change in concentration of the four major cations with discharge.Glacier grinding is considered as a factor favouring cation exchange in a proglacial environment.