Potassium Ion Exchange Research Articles

In situ potassium and hydrogen ion exchange into a cubic zirconium silicate microporous material.

The selective separation of ions from aqueous systems, and even in the human body, is a crucial to overall environmental management and health. Nanoporous materials are widely known for their selective removal of cations from aqueous media, and therefore have been targeted for use as a pharmaceutical to treat hyperkalemia. This study investigated the detailed crystallographic molecular mechanisms that control the potassium ion selectivity in the nanoporous cubic zirconium silicate (CZS) related materials. Using time-resolved in situ Raman spectroscopy and time-resolved in situ X-ray diffraction, the selectivity mechanisms were determined to involve a synchronous cation-cation repulsion process that serves to open a favorable coordination bonding environment for potassium, not unlike the ion selectivity filter process found in potassium ion channels in proteins. Enhancement of ion exchange was observed when the CZS material was in a partial protonated state (≈3:1 Na:H), causing an expansion of the unit-cell volume, enlargement of the 7 member-ring window, and distortion of framework polyhedra, which allowed increased accessibility to the cage structures and resulted in rapid irreversible potassium ion exchange.

A Novel Composite Hydrogel Material for Sodium Removal and Potassium Provision.

Sodium ions are commonly found in natural water sources, and their high concentrations can potentially lead to adverse effects on both the water sources and soil quality. In this study, we successfully synthesized potassium polyacrylate (KMAA) hydrogel through free radical polymerization and evaluated its capability to remove sodium ions from and supply potassium ions to aqueous solutions. To assess its performance, inductively coupled plasma emission spectroscopy (ICP) was employed to analyze the sodium ion removal capacity and potassium ion exchange capability of the KMAA hydrogel at various initial sodium ion concentrations and pH values. The results demonstrated that the KMAA hydrogel exhibited remarkable efficiency in removing sodium ions and providing potassium ions. At pH 7, the maximum adsorption capacity for sodium ions was measured at 70.7 mg·g-1. The Langmuir model, with a correlation coefficient of 0.98, was found to be more suitable for describing the adsorption process of sodium ions. Moreover, at pH 4, the maximum exchange capacity for potassium ions reached 243.7 mg·g-1. The Freundlich model, with a correlation coefficient of 0.99, was deemed more appropriate for characterizing the ion exchange behavior of potassium ions. In conclusion, the successfully synthesized KMAA hydrogel demonstrates superior performance in removing sodium ions and supplying potassium ions, providing valuable insights for addressing high sodium ion concentrations in water sources and facilitating potassium fertilizer supply.

Preparation of Alumina-Sphere-Supported Potassium Chabazite Zeolite Membrane with Excellent Potassium Extraction Performance at Room Temperature

In this paper, a potassium chabazite (KCHA) zeolite membrane was prepared by coating KCHA zeolite on the surface of a porous alumina sphere. The performance of the KCHA zeolite membrane in extracting potassium from seawater and sea bittern at room temperature was studied in detail. The XRD results show that the prepared KCHA zeolite was a KCHA membrane. The EDS test indicated that the potassium content of the KCHA zeolite membrane reached a value of 18.33 wt.%. The morphology of the KCHA zeolite grown on the surface of the alumina sphere was similar to a sphere, and it had good symmetry. The potassium ion-exchange capacities of the KCHA zeolite membrane reached 32 mg/g in seawater and 77 mg/g in sea bittern at room temperature. Ion exchange between the ammonium ions and potassium ions in the KCHA zeolite membrane could be completed in a short time at room temperature. The KCHA zeolite membrane was proven to have good reusability in seawater and sea bittern. The selective ion-exchange mechanism of the KCHA zeolite membrane was controlled by a specific K+ ion memory.

Investigation of Chloroquine Resinate Feasibility and In Vitro Taste Masking Evaluation for Pediatric Formulations.

In this study, chloroquine resinates were prepared at a 1:1 (w:w) drug-to-resin ratio using the batch method with polacrilex (PC), sodium polystyrene sulfonate (SPS), and polacrilin potassium (PP) ion exchange resins (IER). The influence of drug/resin ratio and pH of the medium on drug loading efficiency was explored. UV-VIS spectrophotometric analysis showed that SPS resin had high loading efficiency for chloroquine diphosphate (CLP), above 89%, regardless of the pH. PP resin was more effective at pH 5.0 (90.68%) than at pH 1.0 (2.09%), and PC resin had only 27.63% of CLP loading efficiency. CLP complexation with IER yielded amorphous mixtures according to results from differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD), thus indicating drug-resin interaction. The taste masking efficiency was evaluated with in vitro methods using an adapted dissolution test and an electronic tongue system. During dissolution tests, SPS released only 1.0% of CLP after 300 s, while PP released over 10% after 90 s in simulated saliva solution. The electronic tongue distinguished the samples containing CLP, resins, and resinates by using multidimensional projection techniques that indicated an effective drug taste masking. In an accelerated stability study, the drug contents did not decrease in chloroquine resinates, and there was no physical degradation of the resinates after 60 days. Using chloroquine resinates therefore represents a novel way to evaluate taste masking in vitro which is relevant for the early formulation development process.

Deoxygenation of methyl laurate: influence of cation and mesoporosity in fau zeolites

Catalytic activity of materials prepared by means of sodium ion-exchange by potassium and cesium in NaY zeolite, was studied in the deoxygenation of methyl laurate, as biodiesel model compound. The increase of the Ion-exchange produced a basicity increase that leads to a lower deactivation in the deoxygenation of methyl laurate, reaching a steady conversion of about 92% for 4 h (time on stream, TOS) with the CsKY zeolite. However, the potassium ion exchange leaded to higher production of bio-hydrocarbons, especially unsaturated (96% of the C10, C11 and C12 production), with higher production of C11 by means of decarbonylation. Furthermore, mesoporosity on the KY zeolite was generated, using SDBS (sodium dodecylbenzene sulphonate) during the synthesis, with the aim of increasing its capacity to process bulky molecules. The presence of mesoporosity in the potassium zeolite allowed a higher tolerance to deactivation maintaining a steady conversion of about 90% for 4 h TOS. The yield to desirable products (C10 to C12 hydrocarbons) was about 37%. Therefore, biofuel upgrading can be carried out using potassium Y zeolite with mesoporosity.

A refined design concept for sulfur-tolerant Pd catalyst supported on zeolite by shape-selective exclusion and hydrogen spillover for hydrogenation of aromatics

Sulfur poisoning of noble metal catalysts has been a major challenge for decades. This work demonstrates the superior sulfur tolerance of a hybrid zeolite-supported Pd catalyst for hydrogenation of tetralin containing benzothiophene. The hybrid catalyst consists of Pd supported on a large-pore acidic zeolite Y (Pd/HY) and a small-pore zeolite A without (Pd/HA) or with surface metal passivation by chemical vapor deposition of SiO2 (SiO2-Pd/HA) and with potassium ion exchange (SiO2-Pd/KA). Pd/HY is very active for tetralin hydrogenation but quickly deactivates after exposure to benzothiophene at high concentration of 100 ppm sulfur. The SiO2-coated Pd/HA shows no activity for tetralin hydrogenation, but continues to activate H2 and serve as a source of hydrogen spillover from Pd/HA since these metal sites are protected from thiophenic sulfur due to size-selective exclusion. Adding K ion-exchanged and SiO2-coated catalyst SiO2-Pd/KA to Pd/HY is even more effective for enhancing sulfur tolerance, both for tetralin hydrogenation and for isomerization of cis-decalin to trans-decalin in the presence of benzothiophene. The turnover frequencies (TOF) of all the catalysts are similar at the exposed sulfur/Pd atomic ratio of around 0.5. With further increase in sulfur/Pd ratio, rapid decline in TOF was observed on Pd/HY, but SiO2-Pd/KA + Pd/HY hybrid catalyst shows a significantly higher TOF than that over Pd/HY, even though SiO2-Pd/KA or SiO2-Pd/HA alone shows no TOF for tetralin hydrogenation. Even after high-dose poisoning at 400 ppm sulfur, the SiO2-Pd/KA + Pd/HY hybrid recovered activity more quickly than SiO2-Pd/HA + Pd/HY, while the latter in turn is much better than Pd/HY alone. These results point to the higher activity for hydrogen spillover from SiO2-Pd/KA where Pd metal sites are protected from not only thiophenic sulfur but also inorganic sulfur H2S by shape-selective exclusion. The present work further establishes the validity of shape-selective exclusion and hydrogen spillover in the design concept proposed for a sulfur-tolerant bimodal acidic zeolite-supported metal catalyst for hydrogenation of naphthalene [C.S. Song, Chemtech, 29 (1999) 26–30], and refines the design concept further for limiting the size of small pore in hybrid catalysts to ∼ 3 Å for restricting access of H2S but allowing entrance of H2. This refined design concept is applicable to other supported monometallic and bimetallic catalysts.

A Polarimetric Interferometer Based on Composite Optical Waveguide for Refractive Index Detection

A sensitive interference refractive index sensor based on composite optical waveguide (COWG) was developed. Sol-gel technique was used to prepare TiO2 sol, and the TiO2 film was fixed on the surface of single-mode potassium ion-exchange (PIE) optical waveguide (OWG) by dip-coating and annealing treatment to fabricate an interference refractive index sensor device. The interference between the zeroth-order transverse electric (TE0) and magnetic (TM0) modes of the laser beam which transport in the COWG caused phase-difference change (Δϕ) of output light signals. Refractive index sensitivity of TiO2/PIE COWG chip was examined by injecting aqueous NaCl solutions and distilled water in turn to detect its Δϕ. Experimental results show that, for the TiO2/PIE COWG its refractive index sensitivity is SRI = (573.09 × 2π)/RIU in the refractive index ranges of 1.3386∼1.36. The sensor sees the advantages of high sensitivity, compact size, simple fabrication, as well as low cost.

Influences of copper-potassium ion exchange process on the optical bandgaps and spectroscopic properties of Cr3+/Yb3+ co-doped in lanthanum aluminosilicate glasses.

In this study, lanthanum aluminosilicate glasses with compositions of 45SiO2–20Al2O3–12.5LaF3–10BaF2–9K2O–1Cr2O3–2.5Yb2O3 (SALBK) were prepared using the conventional melting method and copper–potassium ion exchange process. Influences of the ion exchange process between copper and potassium on the visible, upconversion, and near-infrared luminescence spectra of Cr3+/Yb3+ co-doped under excitations of 343, 490, and 980 nm LD were investigated. The EDS analysis of SALBK glasses was measured to confirm the presence of atoms in the glasses. The values of direct and indirect bandgaps of Cr3+/Yb3+ co-doped SALBK glasses were calculated and analyzed. Besides, the energy exchange processes between Cu+, Cu2+ ions, and Cr3+, Yb3+ ions were also proposed and discussed.

Highly sensitive optical waveguide sensor for SO2 and H2S detection in the parts-per-trillion regime using tetraaminophenyl porphyrin

ABSTRACTOptical waveguide (OWG) sensors present great potential for detecting trace levels of harmful gases because of their high sensitivity and anti-electromagnetic interference. However, OWG-based SO2 and H2S-detecting sensors in the parts-per-trillion (ppt) range are still lacking. We fabricated 5,10,15,20-(tetra-4-aminophenyl) porphyrin (TAPP) thin film-based OWG sensor devices (TAPP-OWG) to detect SO2 and H2S gases, in which TAPP thin film was immobilized over the surface of a potassium ion exchange glass OWG. These sensors successfully measure extremely low concentrations of SO2 and H2S (detection limit = 1 ppt), providing good repeatability for SO2 (10 ppt) and H2S (10 ppt) gases, with relative standard deviations of 1.67% and 3.68%, respectively. With fast response (t1) and recovery (t2) times for SO2 (t1=4 s, t2=157 s) and H2S (t1=2 s, t2=117 s) at room temperature, TAPP thin film enhances the potential of OWGs for use in high-sensitivity trace-level gas detection.

Preparation of potassium intercalated carbons by in-situ activation and speciation for CO2 capture from flue gas

Nitrogen and/or sulfur doped carbons were extensively investigated as CO2 adsorbents, however their performance in CO2 capture from combustion flue gas, which is the largest stationary emission source, was less promising. Herein, potassium was used as a dopant for carbon, and a new series of materials, namely potassium intercalated carbons (PICs), were prepared sequentially by oxidation of mesoporous carbon, potassium ion exchange, and calcination. Based on results from FT-IR, XPS, TG-MS, etc., it was found the pre-loaded potassium interacted with the carbon matrix during calcination, enabled great flexibility in: (1) porosity adjustment by “in-situ activation”, and (2) surface chemistry manipulation by potassium intercalation. Taking together, the optimized sample (PIC-700) showed fast and stable CO2 uptake of 5.23 wt.% in flue gas conditions (40 °C, 1 bar, 15%CO2), which is among the highest for carbon-based adsorbents. Such promising performance is directly related to the enhanced CO2 affinity due to the presence of potassium dopants. Dynamic separation of CO2 from 15%CO2/85%N2 showed similar adsorption capacity, and no performance decay could be observed during temperature swing cycles, demonstrating the great potential for the PICs for practical CO2 capture applications.

Syntheses, structural variants and characterization of A2CdSn2S6 (A = Cs, Rb and K) compounds

Four new A2CdSn2S6 (A = Cs(1), Rb(2), K(3-β) and K(3-α)) compounds have been synthesized and characterized by X-ray diffraction and spectroscopic methods. The isostructural cesium(1) and rubidium(2) compounds have noncentrosymmetric three-dimensional tetrahedral [CdSn2S6]2- framework structure and show second-harmonic-generation response. The layered potassium compounds, 3-β and 3-α, have centrosymmetric tetrahedral and octahedral [CdSn2S6]2- framework structures respectively and the compound 3-β, on heating, transforms to compound 3-α. The compound 3-α undergoes facile potassium ion-exchange in aqueous medium with various mono-, di- and tri- valent cations at room temperature.

Identification and characterization of gene in

Toxoplasma gondii is an obligate intracellular protozoan that causes toxoplasmosis. Previous studies have shown that the perturbation of mitochondrial metabolism in T. gondii results in growth deficiency in host cells and lack of virulence in animals. Members of this Letm1 protein family are inner mitochondrial membrane proteins which play a role in potassium and hydrogen ion exchange. Letm1 has not been characterized in T. gondii. In this study, a potential TgLetm1 gene (TgGT1_288400) with Letm1-like protein domain coding sequence was identified in T. gondii. Indirect immunofluorescence assays suggested that TgLetm1 localized to the mitochondria in tachyzoites, as indicated by the colocalization with mitochondrial marker Mitotracker. TgLetm1 was found in the membrane fraction by western blot analysis. To investigate the role of TgLetm1 in T. gondii, we generated a tetracycline-inducible TgLetm1-knock-down mutant. The conditional deletion of TgLetm1 resulted in mitochondrial swelling. Functional studies showed that the conditional deletion of TgLetm1 resulted in growth inhibition, deficiency in invasion and replication, and lack of virulence in mice.

Influence of silver and potassium ion exchange on physical and mechanical properties of soda lime glass

This study aims to investigate the ion exchanged soda lime glasses in terms of their physical and mechanical properties. By the motivation of preparing mechanically strengthened glass also representing antimicrobial property, commercial soda lime glass was subjected to ion exchange treatment using AgNO3KNO3 mixed salt bath. Ion exchange treatment was performed using different salt bath concentrations at varying temperatures and time. After the ion exchange treatment, glass samples were examined by considering the amount of incorporated silver and potassium into the glass, density changes and the variation of the transmittance in the visible region. Treated glasses were further investigated by means of their surface and mechanical properties such as wettability, indentation behaviors including hardness and resistance to indentation cracking, scratch resistance and bending strength. The transmission of the treated glasses showed a decrease due to the coloring effect of silver. Wettability of the glass surface was reduced, while hydrophilicity was decreased after the ion exchange treatment. Almost 20% increase in the Vickers hardness values, substantial enhancement in the indentation crack resistance and scratch resistance as well as averagely 3.5–4 times higher bending strength were achieved for all of the treated glass samples compared to the untreated glass. This study addressed that the simultaneous incorporation of silver and potassium provided significant improvements on the mechanical properties of the soda lime glass.

An examination of isotherm generation: Impact of bottle-point method upon potassium ion exchange with strong acid cation resin

This paper relates to the importance of impact of the chosen bottle-point method when conducting ion exchange equilibria experiments. As an illustration, potassium ion exchange with strong acid cation resin was investigated due to its relevance to the treatment of various industrial effluents and groundwater. The “constant mass” bottle-point method was shown to be problematic in that depending upon the resin mass used the equilibrium isotherm profiles were different. Indeed, application of common equilibrium isotherm models revealed that the optimal fit could be with either the Freundlich or Temkin equations, depending upon the conditions employed. It could be inferred that the resin surface was heterogeneous in character, but precise conclusions regarding the variation in the heat of sorption were not possible. Estimation of the maximum potassium loading was also inconsistent when employing the “constant mass” method. The “constant concentration” bottle-point method illustrated that the Freundlich model was a good representation of the exchange process. The isotherms recorded were relatively consistent when compared to the “constant mass” approach. Unification of all the equilibrium isotherm data acquired was achieved by use of the Langmuir Vageler expression. The maximum loading of potassium ions was predicted to be at least 116.5g/kg resin.

Sm3+-doped fluorophosphate glass: Formation of Ag nanoparticles via Ag+/K+ ion exchange and their effects on optical and dielectric properties

Silver–potassium ion exchange on Sm3+-doped fluorophosphate glass has been carried out via thermal diffusion method. The crystallite size of silver was estimated to be 19nm from X-ray diffraction pattern and it was confirmed using transmission electron microscopy analysis. Assessment of the optical properties has been carried out by absorption, photoluminescence and lifetime measurements. Present glass system exhibits favorable optical properties for possible uses as optical amplifiers, sensors and planar waveguides. The energy transfer mechanism from silver to samarium and the surface plasmon resonance of silver nanoparticles are discussed for the ion exchanged glass. The dielectric studies have been carried out in order to assess the influence of silver on the dielectric properties and ac conductivity of the ion exchanged glass. Coulomb blockade effects have been discussed to clarify the enhancement in the insulating behavior of the glass by the incorporation of silver nanoparticles. The power-law and Cole–Cole parameters were determined and the influence of silver on these parameters is discussed.

Sorption of cesium in young till soils

Abstract Soil samples from three forest soil pits were examined down to a depth of approximately three metres using 1 M ammonium acetate extraction and microwave-assisted extraction with concentrated nitric acid (HNO3), to study the binding of cesium (Cs) at Olkiluoto Island, southern Finland. Ammonium acetate was used to extract the readily exchangeable Cs fractions roughly representing the Cs fraction in soil which is available for plants. Microwave-assisted HNO3 extraction dissolves various minerals, e.g. carbonates, most sulphides, arsenides, selenides, phosphates, molybdates, sulphates, iron (Fe) and manganese (Mn) oxides and some silicates (olivine, biotite, zeolite), and reflects the total Cs concentrations. Cs was mostly found in the strongly bound fraction obtained through HNO3 extraction. The average Cs concentrations found in this fraction were 3.53 ± 0.30 mg/kg (d.w.), 3.06 ± 1.86 mg/kg (d.w.) and 1.83 ± 0.42 mg/kg (d.w.) in the three soil pits, respectively. The average exchangeable Cs found in the ammonium acetate extraction in all three sampling pits was 0.015 ± 0.008 mg/kg (d.w.). In addition, Cs concentrations in the soil solution were determined and in situ distribution coefficients (K d) for Cs were calculated. Furthermore, the in situ K d data was compared with the Cs K d data obtained using the model batch experiments. The in situ K d values were observed to fairly well follow the trend of batch sorption data with respect to soil depth, but on average the batch distribution coefficients were almost an order of magnitude higher than the in situ K d data. In situ Cs sorption data could be satisfactory fitted with the Langmuir sorption isotherm, but the Freundlich isotherm failed to fit the data. Finally, distribution coefficients were calculated by an ion exchange approach using soil solution data, the cation exchange capacity (CEC) as well as Cs to sodium (Na) and Cs to potassium (K) ion exchange selectivity coefficients. The calculated distribution coefficients corresponded well with the in situ distribution coefficient values.

Removal of 2,4-dimethylphenol pollutant in water by ozonation catalyzed by SOD, LTA, FAU-X zeolites particles obtained by pseudomorphic transformation (binderless)

Advanced oxidation processes (AOP) as ozonation coupled with inorganic materials have been recently demonstrated to be highly suitable for wastewater treatment. In petrochemical wastewaters, pollutants as alkylphenols are often detected. In this paper, we highlight the efficiency to couple ozone with zeolites as SOD, LTA and FAU-X for the degradation of 2,4-dimethylphenol (2,4-DMP). For process requirement the 3 zeolites were prepared as particles of 70μm and 1mm thanks to pseudomorphic transformation without binders. The zeolites were synthesized under their sodium (Na) form and potassium (K) ion-exchange was performed to enhance their basicity. By single ozonation (without zeolite) 100% of 2,4-DMP removal occurred in 25min, but the pollutant is transformed into oxidized by-products corresponding to only 14% of the Total Organic Carbon (TOC) removal after 5h. Adding zeolites to the ozonation process increased very slightly the kinetic of disappearance of the pollutant but increased the removal of its oxidation by-products, with 34% of TOC removal after 5h. Among the zeolites, the best solid catalyst for ozonation was Na-LTA. Experiments with tert-butanol (t-BuOH) put in evidence that Na-LTA generates hydroxyl radicals from ozone, which increased the degradation of the by-products. No adsorption of 2,4-DMP and of the resulting oxidation by-products was detected by thermogravimetric analysis (TGA) on the materials after 5h of ozonation. The TOC removal is consequently equivalent to the total mineralization of the organics into CO2.

Optical planar waveguide for cell counting

Low cost counting of cells has medical applications in screening, military medicine, disaster medicine, and rural healthcare. In this report, we present a shallow, buried, planar waveguide fabricated by potassium ion exchange in glass that enables low-cost and rapid counting of metal-tagged objects that lie in the evanescent field of the waveguide. Laser light transmitted through the waveguide was attenuated proportionately to the presence of metal-coated microstructures fabricated from photoresist. This technology enables the low-cost enumeration of cells from blood, urine, or other biofluids.

Blocking of sodium and potassium ion-dependent adenosine triphosphatase-α1 with ouabain and vanadate suppresses cell–cell fusion during RANKL-mediated osteoclastogenesis

To examine the possible enrolment of Na(+)/K(+)-ATPase during osteoclast differentiation, Na(+)/K(+)-ATPase inhibitors, including ouabain and vanadate, were used in this study. These inhibitors significantly inhibited cell-cell fusion of RAW264.7 cells and bone marrow cells induced by RANKL. Interestingly, in response to RANKL-stimulation, ouabain and vanadate decreased the number of large TRAP+ osteoclasts in the culture of RAW264.7 cells, as well as bone marrow cells. In contrast, the number of small TRAP+ osteoclasts either increased in RAW264.7 cells or were otherwise less affected in bone marrow cells than large TRAP+ osteoclasts. Large TRAP+ osteoclasts are defined as having ≥ 10 nuclei/cell and having more potency in bone resorption than small multinuclear osteoclasts with <9 nuclei/cell. Na(+)/K(+)-ATPase α1 and β2 mRNAs were detected in sRANKL-stimulated RAW264.7 cells. Moreover, real-time quantitative PCR showed that ouabain and vanadate suppressed the RANKL-dependent induction of the osteoclast fusion-promotion molecule DC-STAMP at the mRNA level. Finally, and importantly, RNAi-mediated suppression of Na(+)/K(+)-ATPase α1 resulted in a diminished number of large TRAP+ osteoclasts in the sRANKL-stimulated RAW264.7 cells, along with the decreased level of DC-STAMP mRNA expression. These findings strongly suggest that blockage of the Na(+)/K(+)-ATPase α1 subunit by ouabain or vanadate caused the inhibition of RANKL-induced cell-cell fusion, resulting in the generation of large osteoclasts through suppression of DC-STAMP expression. Thus, in addition to its known function of sodium and potassium ion exchange during bone resorption by mature osteoclasts, this study has revealed a novel molecular role of the Na(+)/K(+)-ATPase α1 subunit in osteoclastogenesis.

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.