Rare Metal Ions Research Articles

Covalent organic framework membranes with vertically aligned nanorods for efficient separation of rare metal ions

Covalent organic frameworks (COFs) have emerged as promising platforms for membrane separations, while remaining challenging for separating ions in a fast and selective way. Here, we propose a concept of COF membranes with vertically aligned nanorods for efficient separation of rare metal ions. A quaternary ammonium-functionalized monomer is rationally designed to synthesize COF layers on porous substrates via interfacial synthesis. The COF layers possess an asymmetric structure, in which the upper part displays vertically aligned nanorods, while the lower part exhibits an ultrathin dense layer. The vertically aligned nanorods enlarge contact areas to harvest water and monovalent ions, and the ultrathin dense layer enables both high permeability and selectivity. The resulting membranes exhibit exceptional separation performances, for instance, a Cs+ permeation rate of 0.33 mol m−2 h−1, close to the value in porous substrates, and selectivities with Cs+/La3+ up to 75.9 and 69.8 in single and binary systems, highlighting the great potentials in the separation of rare metal ions.

Comprehensive extraction study using N,N-dioctylthiodiglycolamic acid: effect of S donor on metal extraction.

Extraction ability of N,N-dioctylthiodiglycolamic acid (T-DODGAA), a soft-base sulfur donor ligand with an amide group and a carboxylic acid connected by a thioether chain, for 56 metal ions have been comprehensively investigated and compared with that of N,N-dioctyldiglycolamic acid (DODGAA) with an etheric oxygen atom, a hard-base donor. The acid dissociation constant (pKa) of the thiodiglycolamic acid framework was determined to be 3.71 ± 0.06 in water (0.1M LiCl, 25°C) by potentiometric titration, indicating that T-DODGAA is a slightly weaker acid than DODGAA (pKa = 3.54 ± 0.03). T-DODGAA can quantitatively extract various metal ions from the 56 metal ions into the organic phase (isooctane) through a proton-exchange reaction. T-DODGAA provided higher extraction performance than DODGAA for Hf(IV), Cr(III), Fe(III), Ni(II), Cu(II), Pd(II), Ag(I), Au(III), Hg(II), Al(III), and Ga(III), especially for soft metal ions. Furthermore, to demonstrate the practical feasibility of T-DODGAA for hydrometallurgy and metal recycling, we performed selective separation tests of rare metal ions such as Sc(III), Ni(II), Co(II), Pd(II), Au(III), In(III), and Ga(III) in metal-mixed extraction systems.

Evidence and Practical Applications of Site Occupancy Theory (SOT) of Eu3+ in Scheelite Compounds.

The determination of the site occupancy of activators in phosphors is essential for precise synthesis, understanding the relationship between their luminescence properties and crystal structure, and tailoring their properties by modifying the host composition. Herein, one simple method was proposed to help determine the sites at which the doping of rare earth ions or transition metal ions occupies in the host lattice through site occupancy theory (SOT) for ions doped into the matrix lattice. SOT was established based on the fact that doping ions preferentially occupy the sites with the lowest bonding energy deviations. In order to provide detailed experimental evidence to prove the feasibility of SOT, several scheelite-type compounds were successfully synthesized using a high-temperature solid-phase method. When Eu3+ ions occupy a similar surrounding environment site, the photoluminescence spectra of the activators Eu3+ are similar. Therefore, by comparing the intensity ratio of photoluminescence spectra and the mechanism of all transitions of KEu(WO4)2, KY(WO4)2:Eu3+, Na5Eu(WO4)4, and Na5Y(WO4)4:Eu3+, it was proved that SOT can successfully confirm the site occupation when doped ions enter the matrix lattice. SOT was further applied to the sites occupied by Eu3+ ion-doped LiAl(MoO4)2 and LiLu(MoO4)2.

Sorption Of Rare Metal Ions by Ionite Based on Diglycidyl Thiourea and Various Amines

The article studies the process of sorption of molybdenum and vanadium ions on anion exchangers obtained on the basis of thiourea, epichlorohydrin and various amines. Various amines (urea, guanidine, melamine, polyethylene polyamine, ethylenediamine, etc.) are used as substances containing ionic groups. The regularities of ion exchange and the main properties of the tested anionites are given, the influence of the pH of the medium and interfering ions in the process of sorption of molybdenum and vanadium ions are studied. For vanadium, the use of empirical partition relations and of an extended Freundlich equation were tested, with promising results. The objective of this paper is to investigate the use of the pH dependent Freundlich model of Gustafsson et al., for describing vanadate(V) sorption to 26 mineral soils (all having less than 12% organic C), and to discuss the possible use of the model for risk assessments. The kinetic curves of the sorption process, the values of the diffusion coefficients for the initial periods of molybdenum sorption are given. In particular, the distribution coefficient of the radiotracers of 99Mo and 131I as homologs of Sg and Ts using the surface modification of chabazite was investigated as liquid-solid system in the present study. The kinetics of molybdenum sorption was carried out under static conditions from an ammonium molybdate solution with a concentration of 1 g/L for molybdenum ions and at pH 4.5–5. Under the same conditions, molybdenum ions are sorbed much faster by the DGT + M anion exchanger in comparison with AN-2F anion exchangers, in which the diffusion coefficient is much lower. The static exchange capacity (SEC) was determined in industrial solutions in the presence of mineral acids (hydrochloric, sulfuric and nitric), usually contained in them. The obtained kinetic equilibrium parameters of the tested anion exchangers were compared with those of industrial polycondensation anion exchangers, such as AN-2F and AN-1.

Fabrication of a bifunctional fluorescent chiral composite based on magnetic Fe3O4/chiral carbon dots@hierarchical porous metal-organic framework

Considering the selective pharmacological activity and ecotoxicity of chiral drugs, the development of chiral materials with the dual functions of enantiomeric recognition and adsorption is of great significance. Herein, a novel bifunctional chiral composite (Fe3O4/CCDs@HP-ZIF-8) which does not contain expensive and rare fluorescent chiral ligands or metal ions, was constructed for the first time by encapsulating chiral carbon dots (CCDs) and magnetic Fe3O4 nanoparticles into hierarchical porous metal-organic frameworks (HP-MOFs). Fe3O4/CCDs@HP-ZIF-8, which integrates fluorescent chiral property, magnetism, and hierarchical porosity, shows enormous potential in enantiomeric recognition and adsorption. Fluorescence detection results demonstrate that Fe3O4/CCDs@HP-ZIF-8 presents different fluorescence quenching for naproxen enantiomers. The limits of detection are determined to be 0.05 μM for S-naproxen (S-Nap) and 0.30 μM for R-naproxen (R-Nap), respectively. Furthermore, the isothermal, kinetic, and thermodynamic adsorption behaviors of Fe3O4/CCDs@HP-ZIF-8 to naproxen enantiomers were systematically studied. Due to its hierarchical porosity, the composite exhibits higher adsorption capacity to naproxen enantiomers compared to the non-hierarchical porous composite. Studies of enantiomeric recognition and adsorption mechanisms affirm that the synergistic effect of multiple mechanisms exists between Fe3O4/CCDs@HP-ZIF-8 and naproxen enantiomers. Finally, the satisfactory recoveries and relative standard deviations in the actual sample assays demonstrate the practicality of Fe3O4/CCDs@HP-ZIF-8 for S-Nap detection. This non-destructive functionalization method creates an innovative pathway for developing advanced multifunctional chiral materials, holding great promise for enantiomeric recognition and adsorption.

Influence of Nafion and PBI Membranes on the Performance of Verdazyl Species in Aqueous Redox Flow Batteries

The concept of redox flow batteries (RFB) was originally patented in 1949 by Dr. Kangro with inorganic active materials like iron- or chromium-ions in mind.[1] Intensive research on inorganic active materials led to the proposal of vanadium based RFBs in 1985 by the Skyllas-Kazacos group, which is the most intensively studied RFB type currently.[2],[3] Organic active materials were introduced in 2009 for RFBs and offer a potential alternative to vanadium as active species, due to potentially lower costs and the replacement of rare metal ions.[4],[5] The class of verdazyl radicals has gathered interest as organic active material for the battery application since the publication of symmetrical coin cells.[6] Verdazyl radicals can be transformed into an oxidized or reduced species by a one electron reaction in organic electrolytes, which motivates the application in symmetrical RFBs.[7] Still, degradation of the verdazyl species during operation of the symmetrical battery in organic electrolytes as well as the theoretical voltage of ≈ 1 V show the need for further optimization of the material class and electrolytes.[6] While previous electrochemical investigations of verdazyl species were limited to organic electrolytes, we used a different approach and investigated the influence of acidic electrolytes on the redox chemistry of this material class.[8] Strongly acidic electrolytes lead to a disproportionation of the radical form. The resulting species differ by two electrons and two protons and show a reversible redox reaction in cyclovoltammetry measurements. This different reaction is of interest for the RFB application due to the fast rate constant as well as the utilization of two electrons.[8] Herein, we take the next step for the possible application of the redox chemistry of verdazyl species in acidic electrolytes into aqueous RFBs by analyzing the influence of the separating membranes. We use 1,3,5-triphenylverdazyl species as model compounds in 1 M sulfuric acid. To investigate the influence of the separating membranes in aqueous RFBs, we use Nafion 211 as commercial standard and compare it to self-made mPBI and O-PBI-based polybenzimidazole (PBI) membranes with a target thickness of ≈ 25 µm. When Nafion membranes are immersed in verdazyl cation solutions, they absorb ≈ 0.5 verdazyl cations per sulfonic acid group from the solution, whereas no absorption was observed for PBI membranes. UV/vis also did not show any changes in the UV/vis spectra of the solution, indicating that the verdazyl cations did not degrade. Beside the chemical stability, the permeability through the membranes is characterized, which is detrimental for the capacity retention in an RFB. To fully characterize the membranes with verdazyl species, the conductivity of the membranes is measured and the influence of the verdazyl species onto the conductivity is investigated. As a last step, symmetrical RFBs of verdazyl species in acidic electrolytes are built and the capacity retention is compared.With this study, we show the detrimental effect of using Nafion in combination with verdazyl species. Nafion 211 shows a high affinity to verdazyl cations and absorbs them from the electrolyte, leading to fast capacity fading of the RFB. PBI membranes show chemical stability as well as low absorption and permeability.Our study presents the one of the next steps towards the implementation of verdazyl species into water-based RFBs by investigating the suitability of PBI membranes for this application. PBI membranes offer overall good stability and beneficial properties for this application, while state-of-the-art Nafion is not applicable.

Ultrasensitive analysis of miRNA-141 based on coordination-mediated lamellar nanostructures of [-TPE-(COOH)4-Al-]nLNs with highly efficient aggregation-induced electrochemiluminescence

In this work, [-TPE-(COOH)4-Al-]nLNs with lamellar nanostructures (LNs) were conveniently synthesized through the high affinity coordination between Al3+ and carboxyl groups of 1,1,2,2-tetra(4-carboxylphenyl)ethylene (TPE-(COOH)4). As there was a strong chelate effect and π-π stacking, the [-TPE-(COOH)4-Al-]nLNs could extend not only on a flat surface, but also in a spatial stack. The obtained [-TPE-(COOH)4-Al-]nLNs exhibited excellent aggregation-induced electrochemiluminescence (AIECL) which was much stronger than that of the TPE-(COOH)4 monomer. Furthermore, through stacking and adjustment of Al3+, they also possessed higher electrochemiluminescence (ECL) efficiency compared to the crystal structure based on TPE-(COOH)4, which has a denser aggregation structure that causes aggregation-caused quenching (ACQ) phenomenon. Meanwhile, the [-TPE-(COOH)4-Al-]nLNs with Al3+ as the coordination center were superior to the coordination aggregation structures with heavy metal or rare metal ions as the coordination centers in terms of cost and biocompatibility. Using [-TPE-(COOH)4-Al-]nLNs as a luminescent material, an ultrasensitive ECL biosensor was fabricated for miRNA-141 detection combined with the cascaded strand displacement amplification (CSDA) strategy. Compared to traditional strand displacement amplification (SDA) reaction, the output DNA usually obtained in the first cycle could further return to attend multiple cycle amplification, resulting in the generation of more output DNA and an obvious signal amplification. The constructed biosensor showed excellent detection performance with a linear range from 1 × 10-18 M to 1 × 10-9 M and a detection limit of 1.2 × 10-19 M. This study provided a more convenient and effective AIECL strategy for tetraphenylethylene (TPE) derivatives and broadened the application of ECL technology in ultra-sensitive biochemical detection.

Phosphorylated calix[4]arene/balsa wood copolymers for selective uranyl extraction from wastewater and seawater

Hyper-crosslinked polymers are frequently used to recover specific guest molecules due to their high porosities, excellent chemical properties, and structural stability. However, the recovery of powder adsorbents poses a significant challenge in the extraction of uranyl from aqueous solutions, which limits their practical application. A phosphorylated calix[4]arene/balsa wood copolymer (C4-W-P) was successfully synthesized and utilized for the extraction of uranyl from radioactive wastewater and seawater. Compared to previously reported adsorbents, C4-W-P demonstrated rapid uranyl capture kinetics, with adsorption equilibrium achieved within 150 min. The material exhibited a monolayer saturation adsorption capacity of 473.9 mg·g−1 at pH 5. Thermodynamic studies confirmed the spontaneous and endothermic nature of the adsorption process. Furthermore, C4-W-P exhibited exceptional structural stability, with only a 9.7 % reduction in adsorption capacity after six adsorption–desorption cycles. Additionally, C4-W-P demonstrated excellent selectivity in simulated wastewater containing 16 rare metal ions and simulated seawater containing an additional five metal ions. The KdU values were recorded to be 1817.2 and 33,265.3 mL·g−1, respectively, for these conditions. These results demonstrate the high-efficiency uranium removal capabilities of C4-W-P under realistic conditions. The abundant phosphate groups (∼1.69 mmol·g−1) on the material surface were identified as the primary adsorption contributors. Overall, this study provides a promising strategy for uranyl extraction with high selectivity and ease of preparation, contributing to environmental protection and economic development.

Deciphering the Role of Gamma Ray Induced Radicals in the Thermoluminescence Process of a Neutral to Cool Daylight Emitting Sr1–xB4O7–Dyx Phosphor through Electron Paramagnetic Resonance (EPR) Spectroscopy

A number of researchers have reported on the thermoluminescence (TSL) properties of many borates activated with rare earths and transition metal ions. However, there are not many reports that pinpoint the role and chemical nature of the gamma induced radicals. Further, there are even fewer reports highlighting the multifunctional characteristics of a single TSL phosphor. In this work, we showcase SrB4O7 doped with Dy3+ for the dual role of white light emitting as well as a TSL dosimetric material. We did the PL/TSL/EPR (electron paramagnetic resonance) correlation studies in order to identify the active luminescent centers, the trap parameters and the chemical nature of the radicals responsible for the phenomena. By doing a systematic study on a series of Dy3+ (1–10 mol %) doped samples, we optimized the composition. Colorimetric studies on the optimized sample revealed that it had intense near white light emission with 38.1% color purity when excited by UV-C light (247 nm). The same sample also showed a linear gamma dose response up to 1600 Gy (J/kg). A detailed EPR investigation confirmed the role of a borate based radical in the observed TSL process. We believe that the material can be a good candidate for real life application as a multifunctional material.

Considerable improved near-infrared luminescence in ionic-free doped ZnAl2O4 by oxygen defects engineering

Recently, the phosphor for near-infrared LED is of importance, and a lot of the researches have been attracted on the synthesis and composition design. However, the large number of researches for near-infrared luminescent materials mainly focus on activator ions doped inorganic materials, including rare earth ions and transition metal ions. Here, an ionic-free doped NIR phosphor of ZnAl2O4 is proposed for NIR LED through oxygen defects engineering. The spinel-structured ZnAl2O4 phosphors with deficiency of zinc were synthesized by high temperature solid state reaction, which were characterized by a series of techniques, including XRD, UV–Vis, XPS, EPR, DFT calculation, PLE/PL spectroscopy, and temperature-dependent PL spectra analysis. The deficiency of zinc results in the appearance of zinc vacancy (VZn) and oxygen vacancy (VO). Most of the oxygen vacancy is VO+, along with a small content of VO++ in ZnAl2O4. Under the excitation of ultraviolet light at 302 nm, the phosphor outputs a broad near-infrared emission band with the maximum at 715 nm. Higher concentration of zinc deficiency leads to stronger near-infrared luminescence, because of the increased oxygen vacancy. The phosphors exhibited a good thermal stability, and they were successfully packaged on the 285-nm UV LED chip, which outputted bright and intense near-infrared light, indicating that the NIR phosphors synthesized in this work have the prospect application in NIR LED.

The uptake characteristics of Prussian-blue nanoparticles for rare metal ions for recycling of precious metals from nuclear and electronic wastes

We have examined the uptake mechanisms of platinum-group-metals (PGMs) and molybdenum (Mo) ions into Prussian blue nanoparticles (PBNPs) in a nitric acid solution for 24-h sorption test, using inductively coupled plasma atomic emission spectroscopy, powder XRD, and UV–Vis-NIR spectroscopy in combination with first-principles calculations, and revealed that the Ru4+ and Pd2+ ions are incorporated into PBNPs by substitution with Fe3+ and Fe2+ ions of the PB framework, respectively, whereas the Rh3+ ion is incorporated into PBNPs by substitution mainly with Fe3+ and minorly with Fe2+ ion, and Mo6+ ion is incorporated into PBNPs by substitution with both Fe2+ and Fe3+ ions, with maintaining the crystal structure before and after the sorption test. Assuming that the amount of Fe elusion is equal to that of PGMs/Mo substitution, the substitution efficiency is estimated to be 39.0% for Ru, 47.8% for Rh, 87% for Pd, and 17.1% for Mo6+. This implies that 0.13 g of Ru, 0.16 g of Rh, 0.30 g of Pd, and 0.107 g of Mo can be recovered by using 1 g PBNPs with a chemical form of KFe(III)[Fe(II)(CN)6].

Generation of Arming Yeasts with Active Proteins and Peptides via Cell Surface Display System: Cell Surface Engineering, Bio-Arming Technology.

The cell surface display system in yeast enables the innovative strategy for improving cellular functions in a wide range of applications such as biofuel production, bioremediation, synthesis of valuable chemicals, recovery of rare metal ions, development of biosensors, and high-throughput screening of protein/peptide library. Display of enzymes for polysaccharide degradation enables the construction of metabolically engineered whole-cell biocatalyst owing to the accessibility of the displayed enzymes to high-molecular-weight polysaccharides. In addition, along with fluorescence-based activity evaluation, fluorescence-activated cell sorting (FACS), and yeast cell chip, the cell surface display system is an effective molecular tool for high-throughput screening of mutated protein/peptide library. In this article, we describe the methods for cell surface display of proteins/peptides of interest on yeast, evaluation of display efficiency, and harvesting of the displayed proteins/peptides from cell surface.

Research progress on degradation of VOCs by metal ions doped titanium dioxide nanoparticles

The use of anatase nanotitanium dioxide (T1O2) is a current research hotspot in this field due to its unique features such as chemical stability, non-toxicity, resistance to photocorrosion and low capital, etc., in the degradation of wastewater and photocatalytic degradation of VOCs. In this paper, the mechanism of VOCs degradation by titanium dioxide nanoparticles is studied, and it is found that this catalyst still has a small visible light absorption range and unstable crystalline shape, which limit its photocatalytic efficiency. Recent research results show that the modification of TiO2 by ion doping can change its charge density, lattice structure and forbidden band width, which can effectively enhance the photocatalytic ability of TiO2 nanoparticles and increase the utilization of visible light. In this paper, we summarize the research progress of titanium dioxide photocatalyst modification by metal ion doping and its application in production in recent years, compare and summarize different doping preparation methods, and outlook the development trend of rare metal ion doped titanium dioxide, in order to prepare highly stable and efficient titanium dioxide nanocatalysts in visible light. It provides a scientific basis and reference for the preparation of highly stable and efficient photocatalysts under visible light, and lays the foundation for the wide application in the field of VOCs degradation.

Coefficient effect of rare earth and metal ions in phosphor combined glass materials for a wide color gamut display.

The surface plasmon resonance (SPR) of metal nanostructures is known to affect the optical properties of solid luminescent materials. Ag nanoparticles were first used to obtain a wider color gamut in rare-earth-doped phosphor-in-glass for application as color filters for white light emitting diodes. The existence of Ag nanocrystallites at nanometer scale and the independent integrity of the phosphor luminescence center in the amorphous glass environment were demonstrated. Using UV-Vis spectroscopy, the localized SPR absorption band was observed at 480 nm, and the optical properties of the nanostructures were found to be dependent on the annealing temperature. Hence, an expansion of the color gamut from 79.07% to 93.31% was realized by the coefficient effect of Nd3+ active ions and Ag nanoparticles. These results suggest that Nd3+-ion-co-doped phosphor-in-glass modified by Ag nanoparticles could be potentially applied as a novel optical material with a wide color gamut.

Tris 2-aminoethyl amine (TREN) agent to quantify interaction and extraction capacity of VO2+ ions for oriented membrane processes

In recent years, the development of functionalized synthetic or natural polymer membranes with good mechanical stability has increased considerably for applications in different extraction and separation membrane processes. The technique of oriented processes through affinity polymer membranes is often adopted for the extraction of rare and value-added metal ions. Different types of affinity polymer membranes have been developed by insertion or grafting of extractive agents such as TREN, to extract and recover VO2+ ions from acid solutions of industrial leaching in order to remedy the massive consumption of the metal vanadium. This research was carried out according to the facilitated transport of VO2+ ions from an acid medium through a polymer membrane functionalized with TREN. The impact and influence of the TREN agent, as well as its concentration on the morphology, porosity, composition, and performance of the developed PSU/PVP/TREN membrane were studied. Different techniques including FITR-ATR Spectroscopy, SEM and EDX Spectroscopy were employed to characterize the membrane. In the present work, the membrane developed and used has good stability and a long lifetime for carrying out the processes studied under hard conditions of acidity and temperature. The performance of the membrane was evaluated by calculating the macroscopic parameters, permeability P and initial flux J0. The apparent diffusion of VO2+ ions through the organic phase according to the formation and dissociation reactions of unstable entities (VO2+ -TREN) was determined by the evolution of microscopic parameters, apparent diffusion coefficient D* and association constant Kass. To justify the results obtained for the process studied, activation and thermodynamic parameters (energy Ea, enthalpy ΔH≠, entropy ΔS≠, and enthalpy ΔHth) were assessed. The evolution analysis of obtained values allows us to elucidate the kinetic or energetic aspects which control the mechanics of the studied processes and the performance of the adopted membrane.

Adsorption Properties for La(III), Ce(III), and Y(III) with Poly(6-acryloylamino-hexyl hydroxamic acid) Resin.

Using polyacrylic resin followed by the substitution reaction with 6-aminohexyl hydroxamic acid, poly(6-acryloylamino-hexyl hydroxamic acid) resin (PAMHA) was successfully synthesized. PAMHA, a spherical resin with the particle size of 0.4 mm, is a novel polyamide hydroxamic acid chelating resin containing acylamino and hydroxamic acid functional groups. A series of influences (pH, contact time, temperature, and the initial concentrations of rare earth ions) were investigated to determine the adsorption properties. The adsorption capacity for La(III), Ce(III), and Y(III) ions were 1.030, 0.962, and 1.450 mmol·g−1, respectively. Thermodynamic and kinetic studies were also carried out to show that the uptake of rare earth ions onto PAMHA fitted well the pseudo-second-order model and Langmuir isotherm, and the adsorption process was spontaneous endothermic. In addition, desorption of rare earth ions was achieved by using 2 mol·L−1 HNO3 and desorption efficiencies for La(III), Ce(III), and Y(III) ions were 98.4, 99.1, and 98.8%, respectively. Properties of PAMHA resin were characterized by scanning electron microscope (SEM), Fourier transform infrared spectrometry (FTIR), and X-ray photoelectron spectrometer (XPS). The results showed that there was coordination between the rare earth ions with PAMHA and rare metal ions were chemically adsorbed on the surface of the PAMHA.

Preparation of a Novel Polystyrene-Poly(hydroxamic Acid) Copolymer and Its Adsorption Properties for Rare Earth Metal Ions.

In this study, a novel polystyrene-poly(hydroxamic acid) copolymer was synthesized as an effective adsorbent for the treatment of rare earth elements. Through the use of elemental analysis as well as FTIR, SEM, XPS, and Brunauer-Emmett-Teller (BET) surface area measurement, the synthesized polymer was found to have a specific surface area of 111.4 m2·g−1. The adsorption performances of rare metal ions were investigated under different pH levels, contact times, initial concentrations of rare earth ions, and temperatures. The adsorption equilibrium for La3+, Ce3+, and Y3+ onto a polystyrene-poly(hydroxamic acid) copolymer is described by the Langmuir model, which confirms the applicability of monolayer coverage of rare earth ions onto a polystyrene-poly(hydroxamic acid) copolymer. The amount of adsorption capacities for La3+, Ce3+, and Y3+ reached 1.27, 1.53, and 1.83 mmol·g−1 within four hours, respectively. The adsorption process was controlled by liquid film diffusion, particle diffusion, and chemical reaction simultaneously. The thermodynamic parameters, including the change of Gibbs free energy (∆G), the change of enthalpy (∆H), and the change of entropy (∆S), were determined. The results indicate that the adsorption of resins for La3+, Ce3+ and Y3+ was spontaneous and endothermic. The polymer was also used as a recyclable adsorbent by the desorption experiment.

PRODUCTION OF SULFOCATIONITE BY MODIFICATION OF NATURAL COAL WITH CONCENTRATED SULFURIC ACID

Monitoring the content of rare metals in environmental objects at the level of their maximumpermissible concentrations is an important environmental task. The widely used physicochemical methods do notalways provide a direct solution to this problem because of the influence of the matrix composition of the sample onthe results of the determinations, as well as low concentrations of the determined elements. This article proposes anew modified sulfonated charcoal based on coal from the Shubarkul deposit for sorption of rare metal ions fromwater bodies. Concentrated sulfuric acid (H2SO4) is used as a modifier. The synthesis of new highly permeable crosslinked, sulfonated cation exchangers and their composition, structure by chemical and physical methods wasinvestigated. The static exchange capacity (SЕС) of sulfonated coal was calculated. The article shows an increase inSEC from the concentration used in the modification of H2SO4. During the synthesis, the static exchange capacity ofsulfonated coal increases at 240 min. heating up. The temperature stability of sulfonated coal is higher to (100-120 °)C. Sulfonated coal refers to medium acid cation exchangers, which work effectively at pH 2-14. The resultingsorption materials are recommended for use in treatment plants for the removal of rare metal ions.

Modulation of Jahn-Teller Mn3+ ion on anisotropy and high field magnetic diagram of Sm(Fe, Mn)O3

SmFeO3 and SmFe0.9Mn0.1O3 single crystal samples grown with a floating zone technique have been investigated under static and pulsed high magnetic fields along all principal crystallographic axes. Comprehensive investigation on magnetization (behavior) show that the spin switch transition and spin reorientation transition among the Sm3+ and Fe3+/Mn3+ sublattices is highly anisotropic. Especially, with the applied magnetic field along a-axis, a field induced multi-step transition was observed in SmFeO3 around compensation temperature (TComp1 ~ 3.9 K), which was not observed in Mn doped SmFe0.9Mn0.1O3 (TComp2 ~ 9.3 K). The experimental results show that the Jahn-Teller (J-T) Mn3+ ions has an important effect on anisotropy and affects the spin-reorientation and high field magnetization behavior. The study provides a clear picture to show the dominate effects between rare earth ions and transition metal ions on the complicated magnetization behavior.

Obtaining and studying composite material based on pani / cnt for extraction of rare metal ions

The physicochemical properties of a composite material for the separation of cerium from sulfuric acid-chloride solutions have been studied. The nanocomposite polyaniline (60 wt%) / CNT CNT was obtained by polymerizing an aniline oxidizer on the CNT surface. The morphological and structural characteristics of the material were obtained using scanning electron microscopy. The optimal synthesis conditions have been identified.