Ion-exchange Method Research Articles

Trace Cu (II) removal from N-methylpyrrolidone with hydrogel rich in O, N and S active sites

The presence of a considerable quantity of metal ions in N-methylpyrrolidone (NMP) applied for the cleaning of electronic devices, especially chips, results in a breakdown effect, thus affecting their overall durability and performance. Here, hydrogel that rich in O, N, and S active sites was prepared, which can effectively remove trace amounts of Cu (II) from N-methylpyrrolidone. The material was synthesized through a one-pot crosslinking and ion exchange method and is named SLH. The physicochemical properties and adsorption experiments were conducted. It was found that SLH-2 exhibited outstanding Langmuir maximum adsorption capacity of 136.99 mg/g at an initial Cu (II) concentration of 200 mg/L. By utilizing SLH-2 in electronic grade adsorption experiments, concentration of trace Cu (II) decreased from 12.3 μg/L to 5.39 μg/L. Additionally, concentration of Zn, Fe, Mg, and Ni significantly reduced to less than 1 μg/L, with –NH2 and –COOH playing crucial roles in the adsorption process. The research results indicate that predominant adsorption mechanisms are surface coordination and ion exchange. The adsorption energy between active functional groups and Cu (II) was calculated using density functional theory (DFT), revealing an affinity order of –COOH > –SO3H > –NH2 > –OH. This work not only developed an adsorbent for capturing trace Cu (II), but also provided new strategies for the removal of metal ions in wet chemicals.

ZIF-67-derived for B-doped NiCoP hollow nanocages as efficient catalysts synergistically promoting NaBH4 hydrolysis

Designing a non-noble metal catalyst with fast charge transfer, high electron density, and abundant active sites is an effective strategy for improving the sluggish kinetics and achieving efficient hydrogen generation (HG) in the NaBH4 hydrolysis process. In view of the influence of heterogeneous elements and microstructure on the catalyst performance, ZIF-67 was initially utilized as a precursor to be converted into a mixed phase containing CoNi-LDH and ZIF-67 with identical microstructure by a controlled strategy of ion-exchange method. After further phosphitylation and immersion in NaBH4 solution, B–NiCoP/NC catalysts were obtained with the hollow nanocage structure consisting of B-doped metal phosphide (NiCoP) as well as nitrogen-doped carbon (NC). The synergistic coupling between the heteroatoms and the distinct microstructure of the optimized B–NiCoP/NC shows a high HG rate (5853.9 mL min⁻1 gcatalyst⁻1) and low activation energy (33.92 kJ mol−1), surpassing the performance of mostly reported similar catalysts. Moreover, B–NiCoP/NC exhibits a retained initial activity of 68.7 % even after six cycles. This work offered one of the referable strategies to improve the performance of non-precious metal catalysts in multiple aspects.

S-vacancy-rich NiFe-S nanosheets based on a fully electrochemical strategy for large-scale and quasi-industrial OER catalysts

The oxygen evolution reaction (OER) is regarded as a critical component in the water splitting system. Creating vacancies, increasing active surface area, and optimizing electronic structure would improve electrocatalytic performance. Herein, a facile electrochemical reduction method is used to generate sulfur vacancies in nickel iron sulfide (NiFe-S) with a large geometry area of 15 × 16 cm2, which is synthesized using an electrodeposition process assisted with the ion exchange (IOE) method. The X-ray absorption spectroscopies (XAS) are applied for atomic-level structural analysis, verifying that electrochemical desulfurization generates abundant S vacancies. The NiFe-S with abundant sulfur vacancies (NiFe-S-Vs) exhibits a low overpotential (252 mV at 100 mA cm−2), and long stability for 260 h at 500 mA cm−2. More importantly, the NiFe-S-Vs catalyst also delivers a small overpotential (235 mV at 1000 mA cm−2) and high alkaline tolerance (140 h at 500 mA cm−2) in 6 M KOH at 60 °C), implying a potentially significant industrial application prospect. Finally, theory calculation further illustrates the high performance of as-prepared vacancies-rich catalyst.

Interfacial electric field construction of hollow PdS QDs/Zn1-xCdxS solid solution with enhanced photocatalytic hydrogen evolution.

The regulation of hollow morphology, band structure modulation of solid solution, and introduction of cocatalysts greatly promote the separation of electron-hole pairs in photocatalytic processes, which is of great significance for the process of photocatalytic hydrogen evolution (PHE). In this study, we constructed Zn1-xCdxS hollow solid solution photocatalysts using template and ion exchange methods, and successfully loaded PdS quantum dots (PdS QDs) onto the solid solution through in situ sulfidation. Significantly, the 0.5 wt% PdS QDs/Zn0.6Cd0.4S composite material achieved a H2 production rate of 27.63 mmol g-1 h-1 in the PHE process. The hollow structure of the composite material enhances processes such as light reflection and scattering, the band structure modulation of the solid solution enables the electron-hole pairs to reach an optimal exciton recombination balance, and the modification of PdS QDs provides abundant sites for oxidation, thereby promoting the proton reduction and hydrogen evolution rate. This work provides valuable guidance for the rational design of efficient composite PHE catalysts with strong internal electric field.

Effective isolation of succinic acid from aqueous media with the use of anion exchange resins.

The primary objective of this study was to examine the isolation of succinic acid (SA) from aqueous-based solutions through the utilization of adsorption and ion exchange methods. Four kinds of anion exchange resins were employed, two of which were strong basic (Lewatit M-500 and Lewatit M-600), and the other two were weak basic (Lewatit MP-64 and Lewatit MP-62). The impacts of various variables on the efficiency of the process were examined. The aqueous pH strongly influenced the separation yield. Weak basic exchangers achieved the maximum yield at pH 2.1. However, the highest performance with Lewatit M-600 and Lewatit M-500 was obtained at pH 5 and 6, respectively. The SA separation with the tested resins reached equilibrium in about an hour. The recovery data revealed consistency with the Langmuir isotherm and pseudo-second-order kinetics. Efficiency improved with resin dosage and reduced with SA concentration. It was found that weak basic anion exchange resins were more efficient than strong basic exchangers for the recovery process. Among the resins tested, Lewatit MP-62 demonstrated the highest sorption capacity of 321 mg g-1 and 97.5% yield. The performance of the system decreased with temperature for all alternatives tested; however, its impact was not notable. The isolation process had an exergonic, exothermic, and favorable character based on the thermodynamic constants. Acid-loaded resins were successfully regenerated using trimethylamine and HCl for weak and strong anion exchange resins, respectively.

Toward The Societal Implementation of Lithium Recovery Process by Ion Exchange Method

Toward The Societal Implementation of Lithium Recovery Process by Ion Exchange Method

Magnetic Modification of Ion Exchange Processes

Today, the ion exchange method is widely used in water treatment systems. Ion exchange systems are used to correct the mineral composition of water to the required standards; wastewater treatment; desalination and softening of natural waters. To present day, there are technical solutions to improve the process of water purification, treatment, softening and demineralization. They include: improvement of physical and chemical conditions; intensification of the ion exchange process; use of new ion exchange materials; modification of ion exchange resins; combination with other water treatment methods; modernization of equipment and designs of ion exchange devices. In order to improve the flow conditions and reduce the burden on the environment, it is promising to implement technologies aimed at intensifying the ion exchange process by activating the components of the process. The paper investigates the effect of magnetic modification on the intensification of ion exchange processes during the adjustment of the mineral composition of natural waters. The obtained results demonstrate the influence of the magnetic field on the ion exchange process.

Bimetal doped Cu-Fe-ZIF-8/g-C3N4 nanocomposites for the adsorption of tetracycline hydrochloride from water.

Bimetal doped Cu-Fe-zeolitic imidazole framework-8 (ZIF-8)/graphitic carbon nitride (GCN) (Cu-Fe-ZIF-8/GCN) nanocomposites were prepared via one-pot and ion-exchange methods. The main influencing factors, such as adsorbent concentration, TC concentration, initial pH, and coexisting ions, were evaluated in detail. Due to the suitable pore structures and the presence of multiple interactions on the surface, the nanocomposite showed a high adsorption capacity up to 932 mg g-1 for tetracycline hydrochloride (TC), outperforming ZIF-8 by 4.8 times. The adsorption kinetics and adsorption isotherm were depicted in good detail using pseudo-second-order kinetic and Langmuir models, respectively. Thermodynamic calculation revealed that the adsorption of the nanocomposite under experimental conditions was a spontaneous heat absorption process, and was primarily driven by chemisorption. After four cycles of use, the nanocomposite retained 87.2% of its initial adsorption capacity, confirming its high reusability and broad application prospects in removing tetracycline-type pollutants from wastewater.

Preferential separation of a radioactive TcO4- surrogate from a mixture of oxoanions by a cationic MOF.

Preferential trapping of a selected metal-oxoanion from a mixture of other metal-oxoanionic toxic pollutants in water has been demonstrated by implementing energy-efficient adsorption followed by the ion-exchange method, utilizing a hydrolytically stable cationic metal-organic framework (MOF). The cationic MOF exhibits ultrafast and selective extraction efficiency towards ReO4- (a surrogate anion of radioactive TcO4-) over other metal-oxoanions in contaminated water systems.

Harnessing solid-state ion exchange for the environmentally benign synthesis of high-efficiency Mn4+-doped phosphors.

In this study, a solid-state ion exchange (SSIE) method is proposed to synthesize a series of Mn4+-doped fluoride phosphors, which avoids the use of HF solution during the Mn4+-doping process. The obtained Mn4+-doped fluoride phosphors exhibit strong red emission with a quantum yield of 46%.

A performance comparison of photo-fenton decolorization of methylene blue by using bentonite/iron composites prepared by liquid phase and solid phase ion exchange method

Nowadays, there is a wide range of pollutants present, which requires the treatment of wastewater. The photo-Fenton method has been recognized as valuable in this area. In this study, iron/bentonite composites were created using both liquid phase and solid phase iron exchange techniques, and they were utilized as a photocatalyst for the degradation of methylene blue through photo-Fenton process. Various factors affecting the photocatalytic decolorization were investigated, including the initial concentration of the dye, weight of the catalyst, pH of the solution, and concentration of hydrogen peroxide. The decolorization efficiency of the iron/bentonite composites prepared using the solid phase and liquid phase ion exchange approaches was found to be 99% and 95%, respectively. Based on the data, it can be concluded that the performance of both catalysts was almost equally influenced by the initial dye concentration, catalyst weight, solution pH, and hydrogen peroxide concentration. Moreover, the solid phase ion exchange method demonstrated greater reusability compared to the liquid phase ion exchange method. Consequently, it can be stated that the solid phase ion exchange approach is a suitable and straightforward alternative to the conventional liquid phase ion exchange method for producing a photo-Fenton catalyst.

Sequential separation of uranium and plutonium in urine sample using UTEVA resin

This article describes the process of separating uranium (U) and plutonium (Pu) sequentially in urine samples through the use of UTEVA resin. The manuscript optimizes several parameters, including the concentration of nitric acid in the loading solution, the repeatability of results across the multiple uses of the column, and most significantly, implementation of distinctive eluting agents. These eluting agents encompass a combination of 0.002M sulfamic acid and 0.002M ascorbic acid in 2M HNO3, as well as 1.5M NH2OH, HCl (hydroxylamine hydrochloride) in 2M HCl, all aimed at enhancing recovery percentages. The selection of 0.002M sulfamic acid and 0.002M ascorbic acid in 2M HNO3 have been observed to be exceptionally effective in achieving higher radiochemical recoveries. The standardized methodology presented here is characterized by its swiftness and robustness, particularly when compared to the traditional ion exchange method and numerous other published works related to extraction chromatography materials. Radiochemical recoveries for spiked urine samples of 232U and 242Pu consistently fall within the range of 93%–100% and 71%–96%, demonstrating an average recovery percentage with a standard deviation of 96.2% ±2.4% and 82.4% ±10.1%, respectively.

Preventing scale formation on heat transfer surfaces

The article considers the problem of scaling in power equipment on the example of Thermal Power Plants in the Republic of Kazakhstan. The most optimal solution is proposed – replacement of the traditional preparation of the feed water in the heat network by an ion exchange method for a more effective method using complex-forming reagents. The influence of inhibitor of mineral salts concentration (IMSC), trisodium phosphate, and Zinc Complex 1-hydroxyethylendiphosphonic acid (Zn-OEDF), as well as the heat carrier temperature on scaling intensity, has been studied to prevent the equipment from scale formation and corrosion. The technological parameters of feed water in the presence and absence of complex formers have been determined. The corrosion resistance of steel No. 3 samples in the presence of said reagents has been studied. The most optimal complexone has been chosen to prepare feed water for the TPP heating network.

Enhanced visible light photocatalytic activity of octopod Ag3PO4 microcrystals with high index crystal faces.

Novel octopod shaped Ag3PO4 microcrystals were successfully fabricated by a simple ion exchange method under the conditions of a hot water bath using [Ag(NH3)2]+ solution and Na2HPO4 solution as the precursors. Meanwhile, sphere and cube shaped Ag3PO4 microcrystals were also prepared followed by changing reaction materials as well as temperature. The surface morphology, microstructure and photocatalytic performance were investigated on the three different shaped crystals respectively. Compared to sphere and cube counterparts, the obtained octopod shaped Ag3PO4 crystals possess 8 symmetric feet with sharp tips and exhibit higher photocatalytic activity and better cycle stability. After further exploring its formation process, UV-vis diffusion reflectance properties as well as photocurrent transient response, it was found that the Ag3PO4 octopod had exposed high index crystal faces, and possessed a narrow band gap as well as high photoexcited transient charge separation efficiency. The results show that the improved photocatalytic activity of octopod shaped Ag3PO4 is mainly due to the synergistic action of the strong light absorption capacity and high carrier separation efficiency. These results highlight the tremendous practical application of octopod Ag3PO4 microcrystals in visible light photocatalysis.

Hydrogen sulfite ion functionalized cationic covalent organic framework nanosheets as a separator boosted the energy storage performance of Li–S batteries

EB-COF:HSO3 was prepared by solvothermal and ion-exchange methods to enhance Li–S battery separators, suppressing the “shuttle effect” of soluble polysulfides and improving charge/discharge efficiencies with excellent electrochemical performance.

In situ preparation of a novel Z-scheme BiOBr/BiVO4 composite film with enhanced photocatalytic CO2 reduction performance

A kind of novel BiOBr/BiVO4 Z-scheme heterojunction composite film is in situ synthesized on Bi substrates via the electrochemical ion-exchange method, and the composite film exhibits excellent photocatalytic CO2 to CO reduction activity.

Realizing a single-phase reaction and K+/vacancy disordering in P2-K0.56Na0.11Li0.12Ni0.22Mn0.66O2 by lithium substitution for potassium-ion batteries

Through the electrochemical ion-exchange method, P2-K0.56Na0.11Li0.12Ni0.22Mn0.66O2 was successfully synthesized as a high-performance cathode with a single-phase reaction and K+/vacancy disordering for potassium-ion batteries.

Cu-SAPO-56, a potential catalyst for the selective catalytic reduction of NOx by NH3

A novel Cu-exchanged catalyst, Cu-SAPO-56 prepared by direct ion exchange method, was studied for NH3-SCR reaction. Cu-SAPO-56 exhibits excellent NH3-SCR activity and hydrothermal stability. The NOx conversion of Cu-SAPO-56 maintains more than 90 % at a wide temperature range between 250 °C and 400 °C even after a rigorous steam treatment (800 °C for 16 h or 50 °C for 24 h). The isolated Cu2+ ions located in double 6-ring of AFX structure are determined as the catalytic active sites. Both of Cu content and Si content in Cu-SAPO-56 play critical roles in NH3-SCR activity and hydrothermal stability. The excellent catalytic performance and strong hydrothermal stability exhibits the huge application potential of Cu-SAPO-56 for NH3-SCR reaction.

Impact of Low-Temperature Water Exposure and Removal on Zeolite HY.

Aqueous-phase postsynthetic modifications of the industrially important Y-type zeolite are commonly used to change overall acid site concentrations, introduce stabilizing rare-earth cations, impart bifunctional character through metal cation exchange, and tailor the distribution of Brønsted and Lewis acid sites. Zeolite Y is known to undergo framework degradation in the presence of both vapor- and liquid-phase water at temperatures exceeding 100 °C, and rare-earth exchanged and stabilized HY catalysts are commonly used for fluidized catalytic cracking due to their increased hydrothermal resilience. Here, using detailed spectroscopy, crystallography, and flow-reactor experiments, we reveal unexpected decreases in Brønsted acid site (BAS) density for zeolite HY following exposure even to room-temperature liquid water. These data indicate that aqueous-phase ion-exchange procedures commonly used to modify zeolite Y are impacted by the liquid water and its removal, even when fractional heating rates and inert conditions much less severe than standard practice are used for catalyst dehydration. X-ray diffraction, thermogravimetric, and spectroscopic analyses reveal that the majority of framework degradation occurs during the removal of a strongly bound water fraction in HY, which does not form when NH4Y is immersed in liquid water and which leads to reduced acidity in HY even when dehydration conditions much milder than those typically practiced are employed. Na+-exchanged HY prepared via room-temperature aqueous dissolution demonstrates that Brønsted acid sites are lost in excess of the theoretical maximum that is possible from sodium titration. The structural impact of low-temperature aqueous-phase ion-exchange methods complicates the interpretation of subsequent data and likely explains the wide variation in reported acid site concentrations and catalytic activity of HY zeolites with high-Al content.

NaY Zeolite Synthesis from Vermiculite and Modification with Surfactant

This work focuses on preparing NaY zeolite using alternative sources of silica and modifying the zeolite with the surfactant cetyltrimethylammonium bromide. Two different hydrothermal synthesis routes were employed: the conventional method using sodium silicate as the silica source, and the other is a sustainable approach using vermiculite clay as the silica source. In traditional zeolite synthesis, sodium silicate is often used as the source of silica. However, . The vermiculite was subjected to an acid treatment, followed by a primary treatment to obtain silica. Using the ion exchange method, the NaY zeolite was modified by an organic surfactant CTABr. Based on the various characterization techniques, it was possible to verify the obtaining of NaY zeolite through the conventional and sustainable routes, in which the structural properties were maintained. They used the sustainable path to synthesize NaY zeolite, which allowed for obtaining a material with low synthesis cost and properties similar to those synthesized conventionally. The structures of the NaY zeolites were maintained after the modification process with the surfactant Cetyltrimethylammonium Bromide (CTABr), demonstrating the structural stability of the zeolites and the efficiency of the modification process.