Ion-exchange Properties Research Articles

Giant Polyoxoniobate-Based Inorganic Molecular Tweezers: Metal Recognitions, Ion-Exchange Interactions and Mechanism Studies.

This work reports the interesting and unique cation-exchange behaviors of the first indium-bridged purely inorganic 3D framework based on high-nuclearity polyoxoniobates as building units. Each nanoscale polyoxoniobate features a fascinating near-icosahedral core-shell structure with six pairs of unique inorganic "molecular tweezers" that have changeable openings for binding different metal cations via ion-exchanges and exhibit unusual selective metal-uptake behaviors. Further, the material has high chemical stability so that can undergo single-crystal-to-single-crystal metal-exchange processes to produce a dozen new crystals with high crystallinity. Based on these crystals and time-dependent metal-exchange experiments, we can visually reveal the detailed metal-exchange interactions and mechanisms of the material at the atomic precision level. This work demonstrates a rare systematic and atomic-level study on the ion-exchange properties of nanoclusters, which is of significance for the exploration of cluster-based ion-exchange materials that are still to be developed.

Crystal structure and ion-exchange property of a lepidocrocite-like sodium titanate

ABSTRACT A lepidocrocite-like potassium titanate, (Kx(LixTi1-x)O2; Lss) with a layered structure can provide a reactive interlayer space for soft-chemical reaction such as ion-exchange or intercalation and the hydrated sodium derivative (Lss-Na) was obtained by an ion-exchange reaction. The crystal structures of the hydrated and dehydrated Lss-Na were refined by using synchrotron powder X-ray diffraction data. Two steps of dehydrated processes for the Lss-Na were observed by in-situ synchrotron powder X-ray diffraction. The ion-exchange property for Lss-Na was superior to those for Lss and Lss-H and was corelated with the effective basal space which was expanded by formation of two layers of water molecules.

Visual demonstration and prediction of the Hofmeister series based on a poly(ionic liquid) photonic array.

The Hofmeister effect and associated Hofmeister series (HS) are ubiquitous in physicochemical phenomena and have demonstrated fundamental importance in a myriad of fields ranging from chemistry to biology. Visualization of the HS not only helps to straightforwardly understand the underpinning mechanism, but also enables the prediction of new ion positions in the HS and directs the applications of the Hofmeister effect. Owing to the difficulties of sensing and reporting complete multiple and subtle inter- and intramolecular interactions involved in the Hofmeister effect, facile and accurate visual demonstration and prediction of the HS remain highly challenging. Herein, a poly(ionic liquid) (PIL)-based photonic array containing 6 inverse opal microspheres was rationally constructed to efficiently sense and report the ion effects of the HS. The PILs can not only directly conjugate with HS ions due to their ion-exchange properties, but also provide sufficient noncovalent binding diversity with these ions. Meanwhile, subtle PIL-ion interactions can be sensitively amplified to optical signals owing to their photonic structures. Therefore, synergistic integration of PILs and photonic structures gives rise to accurate visualization of the ion effect of the HS, as demonstrated by correctly ranking 7 common anions. More importantly, assisted by principal component analysis (PCA), the developed PIL photonic array can serve as a general platform to facilely, accurately, and robustly predict the HS positions of an unprecedented amount of important and useful anions and cations. These findings indicate that the PIL photonic platform is very promising for addressing challenges in the visual demonstration and prediction of HS and promoting a molecular-level understanding of the Hoffmeister effect.

CARACTERIZAÇÃO DE RESÍDUOS SÓLIDOS INDUSTRIAIS POR ANÁLISE TÉRMICA: PERSPECTIVAS DE USO COMO MATERIAL FILTRANTE PARA ÁGUAS RESIDUÁRIAS

CHARACTERIZATION OF SOLID RESIDUES THROUGH THERMAL ANALYSIS: UTILIZATION PERSPECTIVE AS FILTER MATERIAL FOR WASTEWATER TREATMENT. Metallurgical waste and vermiculite are solid residues that have potential of utilization as filtering material. Nevertheless, they are commonly discarded. These materials have chemical sites like Si-O, Si-O-Si in vermiculite or have good ionic exchange properties like iron oxide compounds that can be used in adsorption processes. When these materials are combined with a synthetic blanket (OH, C=C, CO and C-H groups), it composes a filter layer with potential to be used in wastewater treatment. In this article, these materials were chemically treated and characterized by Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and coupled TG-FTIR. The results suggest that organic compound contamination was not found after chemical treatment, which could have remained over the unity operations in the Metallurgical processes. The thermal and acid treatments influenced a major formation of iron oxide formation, but its oxidation degree (FeO, Fe2O3, or Fe2O3.FeO) were dependent on the sample granulometry. The Vermiculite shows an irreversible chemical modification after thermal treatment. The characterization of these residues shows its potential use as material in filter construction. Hence, it is fundamental to minimize the environmental impacts as well as to diminish the production costs in wastewater treatment.

Effect of Brassinosteroids on the Ion-Exchange Properties of the Cell Walls of Barley Roots and Shoots under the Action of Heavy Metals

The effect of polymetallic contamination and concomitant treatment with brassinosteroids (homocastasterone or homobrassinolide) on barley plants and on the ion-exchange capacity of cell walls isolated from shoots and roots was studied. Under the influence of polymetals, a decrease in the dry mass of roots, water content, and the proportion of the cell wall in them was observed, but the addition of homocastasterone to the medium led to the restoration of these parameters almost to the control level. In the aerial part of plants, the influence of both polymetals and brassinosteroids on these parameters was weakly expressed. In the presence of homocastasterone, the content of demethylated carboxyl groups of polygalacturonic acid increased in the pectins of the cell walls of roots and leaves, which are the main binding sites for heavy metal ions in the apoplast. Thus, it can be assumed that treatment with brassinosteroids (homocastasterone) leads to a change in the composition and ion-exchange properties of the cell wall, which makes it possible to reduce the toxic effect of polymetals due to their immobilization in the apoplast.

Synthesis, characterisation, ion chelation exchange capability and antibacterial properties of the <em>o-cresol-formaldehyde-catechol-</em>based copolymer

An ion exchange resin chelator was synthesized from o-cresol, catechol and formaldehyde through the condensation process in the molar ratio of 1:3:5 in the presence of 1 M hydrochloric acid as a catalyst. The resulting copolymer was characterized by IR spectral data. The cation exchange capacity was measured; the effect of metal ion concentration, pH effect, and the ratio of the cation exchange reaction were studied. The chelation ion-exchange properties were also studied with the batch equilibrium method. The formed copolymer chelation ion-exchange properties of the copolymer were analyzed for Cd²⁺, Cr²⁺, Fe²⁺ and Mg²⁺ ions. The resin was proved selective chelating ion- exchange copolymer for the above metals. The study was carried out over a wide pH range and in media of various ionic concentrations for the metals. The antibacterial properties of the synthesized resin were also investigated, using the well diffusion method for the gram-positive bacteria, <em>Staphylococcus aureus </em>and the gram-negative bacteria <em>E coli. </em>The results showed a significant inhibiting effect against the tested bacteria, against the formed resin copolymer.

Modeling the Conductivity and Diffusion Permeability of a Track-Etched Membrane Taking into Account a Loose Layer.

The microheterogeneous model makes it possible to describe the main transport properties of ion-exchange membranes using a single set of input parameters. This paper describes an adaptation of the microheterogeneous model for describing the electrical conductivity and diffusion permeability of a track-etched membrane (TEM). Usually, the transport parameters of TEMs are evaluated assuming that ion transfer occurs through the solution filling the membrane pores, which are cylindrical and oriented normally to the membrane surface. The version of the microheterogeneous model developed in this paper takes into account the presence of a loose layer, which forms as an intermediate layer between the pore solution and the membrane bulk material during track etching. It is assumed that this layer can be considered as a "gel phase" in the framework of the microheterogeneous model due to the fixed hydroxyl and carboxyl groups, which imparts ion exchange properties to the loose layer. The qualitative and quantitative agreement between the calculated and experimental concentration dependencies of the conductivity and diffusion permeability is discussed. The role of the model input parameters is described in relation to the structural features of the membrane. In particular, the inclination of the pores relative to the surface and their narrowing in the middle part of the membrane can be important for their properties.

Ion Exchange in Natural Clinoptilolite: Aspects Related to Its Structure and Applications

Clinoptilolite is one of the most common, widespread and abundant zeolites in nature. Its availability, low cost, and outstanding ion exchange properties make clinoptilolite an excellent candidate for both direct use and various modifications to create new low-cost functional materials for sustainable development. Specific applications in which clinoptilolite is already being used include water treatment and heavy metal ion removal, agricultural purposes, storage and conversion of unwanted gaseous emissions into the atmosphere, production of catalysts and photocatalysts, bioactive materials, and a number of others. Unlike some other zeolites, clinoptilolite is difficult to synthesize, which is why most publications refer to this zeolite in its natural form, either directly from the deposit or after applying various processes to this mineral to improve its properties. Among the modification methods used, ion exchange stands out. This review is devoted to the study of ion exchange processes in natural clinoptilolite with two goals: first, as its strategic property for use in processes in which cation exchange is fundamentally necessary; second, as a way to modify it to create composite materials with predetermined desired properties.

Size-based selectivity of magnetic-layered double hydroxide (MLDH) for efficient removal of oxytetracycline in the presence of natural organic matter

While the adsorption process plays an essential role in antibiotics removal from water, one major problem for applying absorbents in actual wastewater is competitive adsorption that is commonly caused by natural organic matter (NOM). Therefore, we aimed to investigate size-based selectivity of magnetic layered double hydroxides (MLDH) as the absorbent in the mixture of oxytetracycline (OTC) and NOM, as MLDH are generally characterized by high specific surface area, limited intercalation, and ion-exchange properties. MLDH were synthesized by the one-step solvothermal method with four different Fe:Mg ratios and then applied in a series of adsorption experiments. In addition, the role of limited interlayer space of MLDH in the adsorption of OTC and NOM was investigated based on molar mass distribution of those organic components. As results, the adsorption behavior of OTC/NOM on MLDH in the binary systems was found to involve chemisorption and multi-layer coverage. Although the competitive adsorption reduced OTC adsorption, Freundlich coefficient of MLDH (KF) for OTC was higher than KF for NOM, indicating that MLDH selectively adsorbed OTC molecules in the presence of NOM. Moreover, the selectivity (α) value of all MLDH, except MLDH with a Fe:Mg ratio of 1:4, indicating substantial selective adsorption. Among the four MLDH, MLDH11 exhibited the highest α, because its smallest interlayer space offers size-based selectivity, which was also supported by the molar mass distribution. The type of NOM did not significantly affect the OTC adsorption efficiency on MLDH. The results confirmed the benefits of limited interlayer space of MLDH, which offers selectivity for adsorption of OMP in water and shows potential applicability for removing other organic micropollutants.

Cataphoretic deposition of an epoxy coating with the incorporation of Ti3C2Tx@Mg-Al layered double hydroxide for long-term active corrosion protection effect

Epoxy composite coating with active corrosion inhibition property was prepared through cathodic electrophoretic deposition with the incorporation of Ti3C2Tx@Mg-Al layered double hydroxides (LDH) hybrid material. Hydrothermal method was adopted to synthesize molybdate (MoO42−)-intercalated MgAl LDH, which was self-assembled on the surface of Ti3C2Tx MXene through electrostatic interaction to improve the zeta potential of the Ti3C2Tx surface to positive value. Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscope, scanning electron microscope, X-ray photoelectron spectroscopy, zeta (ζ) potentials test and uv-vis spectroscopic analysis results showed that MgAl LDH and Ti3C2Tx@Mg-Al LDH were successfully prepared and Ti3C2Tx@Mg-Al LDH had ion exchange property. The prepared LDH and Ti3C2Tx@Mg-Al LDH were added to electrophoretic paint as anti-corrosive additives. After deposition process of 150 V for 2 min on the P110 steel surface, composite coatings had thicknesses of ~110 μm. Electrophoretic deposition has advantages in controlling coating thickness than traditional spray method. Moreover, Ti3C2Tx@Mg-Al LDH additive endowed composite coating with active corrosion inhibition capacity through ions exchange property between corrosive medium Cl− and MoO42− in the MgAl LDH interlayer. Electrochemical impedance spectroscopy (EIS) test results showed that Ti3C2Tx@Mg-Al LDH/epoxy coating exhibited outstanding corrosion protection property. This research provides a new way of using Ti3C2Tx MXene in the cathodic electrophoretic paint to prepare active anti-corrosive coating.

Mechanochemical Synthesis and Study of the Local Structure of NaGaS2 Glass and Glass-Ceramics.

NaGaS2 is a newly discovered compound that has already shown great promise for a variety of applications because of its layered structure and ion exchange properties. In this work, crystalline NaGaS2 has been synthesized by an alternative method to what has been previously published, namely, by mechanochemistry, either by a direct one-step process or by a two-step process. In the one-step process, crystalline NaGaS2 is directly formed by milling sodium sulfide Na2S and gallium(III) sulfide Ga2S3. However, an amorphous material is present in majority together with the crystalline phase. In the two-step process, amorphous NaGaS2 is first obtained by mechanical milling and then heated above its glass transition temperature to obtain a glass-ceramic mainly composed of crystalline NaGaS2. For the two-step process, changes of the local atomic-level structure in amorphous NaGaS2 and after crystallization were analyzed by high-field solid-state nuclear magnetic resonance (NMR) spectroscopy as well as by X-ray total scattering and pair distribution function (PDF) analysis. Based on quantitative analysis on the 23Na NMR spectra, modifying the annealing treatment can promote the formation of the crystalline phase up to a molar fraction of 83.8%.

Capacitive Desalination and Disinfection of Water Using UiO-66 Metal-Organic Framework/Bamboo Carbon with Chitosan.

The zirconium-based metal-organic framework (MOF) (UiO-66)/bamboo carbon (BC) composite with chitosan was prepared using hydrothermal and impregnation methods and used for capacitive desalination (CDI) and disinfection of water. The results showed that these composites had fast ion exchange and charge transfer properties. During the CDI process, these composites' electrodes exhibited good cycle stability, electrosorption capacity (4.25 mg/g) and excellent bactericidal effect. These carbon-based composites electrodes' bactericidal rate for Escherichia coli could reach 99.99% within 20 minutes; therefore, they had good performance and were a good choice for high-performance deionization applications.

Kinetics of Ion-Exchange Extraction of Lithium from Aqueous Solutions by Protonated Potassium Polytitanates

In this work, protonated forms of potassium polytitanate were obtained by treating the precursor in HCl solution at pH 2.0, 3.0, 4.0, 5.0, 6.0, or 7.0. The synthesized materials were studied using XRD, FTIR, and XRF. The ion-exchange properties were studied using a LiCl solution with a concentration of C(Li+) = 0.01 mol/L. It was shown that extraction of lithium by potassium polytitanates is dependent on their protonation degree. It has been established that the samples with the highest degree of protonation obtained at pH = 2.0 and 3.0 have the highest efficiency in the ion-exchange extraction of Li+ ions from an aqueous solution. For determination of exchange ion rates and the mechanism of the ion-exchange process, pseudo-first- and pseudo-second-order models as well as the Weber–Morris intraparticle diffusion model, were employed. Experimental data with their participation are in good agreement with the pseudo-second-order kinetic model. The calculated kinetic parameters were qe = 0.47–0.52 mmol/g and k2 = 0.25–0.43, depending on the protonation degree of potassium polytitanate. The obtained experimental and calculated values of the sorption capacity were compared with the cation-exchange capacity of materials studied. According to the kinetics study, the mechanism of lithium adsorption by potassium polytitanates with a higher protonation degree is the ion-exchange chemical reaction. Low-cost protonated potassium polytitanates are promising to extract Li+ ions from aqueous solutions with a low concentration, as confirmed by the analysis of the results.

Combination of Moringa Oleifera Seed Powder and Iron Sulfate Heptahydrate Salt as Biopolymer Based Matrix for Application as Adsorbent for Odor Inhibition in Poultry Farms

A biopolymer based matrix of M. Oleifera Seed Powder (MOSP) and Ferrous Sulphate Heptahydrate (FSH) salt was formulated as adsorbent for odor inhibition in poultry farms. The matrix was characterized using FT-IR technique and its performance as adsorbent for NH4+ removal from aqueous solutions was examined via sorption studies. The result showed an excellent sorption performance at 0.1 g sorbent dosage, pH of 9 and 30 min agitation time. This indicates that the matrix possess an excellent ion exchange property and thus a suitable sorbent for NH4+ even in low concentration environment. The study reveals the capacity of the adsorptive matrix as a safe and cost-effective method to be used for ammoniacal odor control from poultry farms which may be applicable to other animal farm operations (AFOs).

Layered double hydroxides (LDHs) modified cement-based materials: A systematic review

AbstractIon erosion and carbonization in concrete are the key factors leading to the deterioration of durability. Layered double hydroxides (LDHs) are a kind of functional material with layered structures and ion exchange properties, which can capture a variety of harmful anions in concrete pore solutions. Therefore, LDHs exhibit great potential in improving the durability of concrete as new modified material. This article reviews the recent progress of LDHs. Based on the structural characteristics of LDHs, this work discusses the binding effect of LDHs on Cl−,SO42−{\text{SO}}_{4}^{2-}, andCO32−{\text{CO}}_{3}^{2-}in cement-based materials. We also analyze the influence of LDHs on the physical, mechanical, and hydration properties of cement-based materials and describe the modification mechanisms. Further, the improved durability of concrete and the corrosion inhibition of reinforcement by LDHs were summarized. Finally, we briefly point out some problems in the current research and development trends in the future on LDHs modified cement-based materials.

METHOD OF EVALUATION OF TRANSFER NUMBERS IN ION-EXCHANGE MATERIALS

A new method of differential itn-metry has been developed for accurate determination of ion transfer numbers in materials with ion-exchange properties. Such materials include ion exchange membranes, liquid phase ion exchangers and ionic liquids, industrial ion exchange resins. The method is intended as an alternative simplified assessment of the functional properties of ion-exchange resins used in industrial technologies of water purification, water treatment, and extraction at enterprises of various industries. Such accurate information is obtained in special laboratories at enterprises by long-term and expensive physical and chemical methods. Transfer numbers give an indirect assessment of the quality of ion exchangers, but the method of differential itn-metry gives a result in a short 30-minute experiment on the electrolysis of a NaOH or NaCl solution in a three-chamber electrolyzer reactor. The electrolyzer-reactor contains an electrolyte volume of up to 40 cm3. The middle chamber of the electrolyzer-reactor has a variable width from 0.05 to 0.2 cm and an area of 10 cm2 perpendicular to the direction of the electric current.&#x0D; The primary result of each experiment was the functions of the electrolyte concentration dynamics C(τ) in the extreme cathode and anode chambers of the electrolyzer- reactor, where the dynamics of the readings of the flow resistometric sensor developed by us were recorded during the electrolysis process. The effective transfer number itn* was determined by mathematical data processing using a system of approximation functions.&#x0D; The method of differential itn-metry will be effective for other resins with amphoteric properties. The use of such a method could be used in works for the study of a wide range of problems in environmental monitoring and management of environmental projects.

Reinforced adsorption mechanism of fluorine ions by calcium-depleted hydroxyapatite and application in the raffinate from the vanadium industry

Calcium-deficient hydroxyapatite (Ca-d HAP), an adsorbent of high defluoridation capacity with lattice defect, was prepared from vanadium industrial waste neutralization slag (NS). The adsorption performance was compared to commercially available stoichiometric HAP (S-HAP) under different solution conditions, and Ca-d HAP was superior to S-HAP. The specific surface area of Ca-d HAP was considerable (118.32 m2/g), which was 3.176 times larger than that of S-HAP (37.25 m2/g), and this was the main reason for the strong adsorption performance of Ca-d HAP. Meanwhile, due to the presence of minor impurities, such as Al and Fe, in NS, the doping of Al and Fe reduced the crystallinity after Ca-d HAP synthesis, which provided additional active sites for binding to other ions. In addition, combined with characterization analysis, it was speculated that some Ca ions in Ca-d HAP were replaced by Na ions with stronger ion-exchange properties, enhancing its adsorption performance. The adsorption mechanism of Ca-d HAP on F- ions was further investigated by discussing the surface potential, initial pH, adsorbent dosage, initial fluorine concentration, adsorption thermodynamics, and kinetics. Results showed that the Langmuir isothermal model well predicts the adsorption behavior of Ca-d HAP on F- ions at pH 3.5, with a maximum adsorption capacity of 277.78 mg/g, which is larger than most HAP adsorbents reported in the literature. In addition, the percentage adsorption of Ca-d HAP on F- ions was > 99 % in the raffinate and the NaF solution. In addition, the percentage adsorption of Ca-d HAP on F- ions was > 99 % both in the raffinate and in the NaF solution. The adsorption of F- ions by Ca-d HAP is a heat absorption process, with the ΔG° < 0 at various temperatures, demonstrating the reaction's spontaneity of the reaction. The pseudo-second-order model better described the adsorption kinetics data at 303 to 333 K, and the adsorption was regulated by chemical reactions. Overall, Ca-d HAP with lattice defects has a large ion-exchange rate and specific surface area, which is the key reason for the high adsorption performance of Ca-d HAP. Therefore, this technology provides a prospect for treating acidic wastewater with high fluorine content in the vanadium industry.

Zeolites as Carriers of Nano-Fertilizers: From Structures and Principles to Prospects and Challenges

The world is facing immense challenges in terms of food security, due to the combined impacts of the ever-increasing population and the adversity of climate change. In an attempt to counteract these factors, smart nutrient delivery systems, including nano-fertilizers, additives, and material coatings, have been introduced to increase food productivity to meet the growing food demand. Use of nanocarriers in agro-practices for sustainable farming contributes to achieving up to 75% nutrient delivery for a prolonged period to maintain nutrient availability in soil for plants in adverse soil conditions. In this context, sieve-like zeolites and the diversity in their structural morphologies have attracted increasing interest over recent years. Engineered nano-porous zeolites, also called aluminosilicates, are defined based on the presence of micro- (&lt;2 nm), meso- (2–50 nm), and macropores (&gt;50 nm), which can be employed as carriers of fertilizers due to their enhanced ion-exchange properties and adsorption capabilities. In this study, we provide a detailed overview of the production and optimization of hierarchical zeolite structures within the size range from micro- to nanometers, as well as the various top-down and bottom-up approaches which have been used to synthesize zeolites with a large surface area, tunable pore size, and high thermal stability, which make them an excellent candidate to be used in agronomy. The delivery of pesticides, insecticides, and fertilizers by loading them into nano-zeolites to manage the crop production without disrupting the soil health is discussed, as well as future perspectives of zeolites in the perpetual maintenance of soil productivity.

Cs6Cl][Ga5GeQ12] (Q = S, Se): two novel porous layered chalcohalides exhibiting two-band emission and ion exchange properties

Cs6Cl][Ga5GeQ12] (Q = S, Se): two novel porous layered chalcohalides exhibiting two-band emission and ion exchange properties

Possible effects of clinoptilolite on small intestinal ischemia-reperfusion injury caused by experimental mesenteric artery occlusion

Abstract Objectives Mesenteric ischemia is a surgical emergency caused by poor blood supply to the intestines. In ischemia, the decrease in blood flow to the tissue causes acidosis and cell death through anaerobic metabolism. Clinoptilolite is one of the most abundant natural zeolites, and it is used for its ion exchange and adsorbent properties. Clinoptilolite has been reported to have an immune-enhancing, anti-carcinogenic, and antioxidant effect in-vitro/in-vivo studies. Clinoptilolite’s histological and biochemical effects on ischemic small intestines. Methods The experimental animals were randomly divided into sham, control, and clinoptilolite treatment group. Clinoptilolite was administered intraperitoneally after ischemia/reperfusion. Cardiac blood was stored for biochemical analysis. Total antioxidant levels and total oxidant levels were analyzed from the sera taken from groups. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) expressions in blood samples were determined by RT-qPCR. At the end of the reperfusion, terminal ileum tissues were taken for histological tests. Results The mean TNF-α expression level was 3.89 in the control group and 2.91 in the clinoptilolite treatment group. The mean IL-6 expression levels were 2.32 in the control group and 1.49 in the clinoptilolite treatment group. Conclusions clinoptilolite administration provided healing in the rat ischemia-reperfusion injury model.