Formation of thermosensitive water‐soluble copolymers with phosphinic acid groups and the thermosensitivity of the copolymers and copolymer/metal complexes

Thermosensitive and water‐soluble copolymers were prepared through the copolymerization of acryloyloxypropyl phosphinic acid (APPA) and N‐isopropyl acrylamide (NIPAAm). The thermosensitivity of the copolymers and copolymer/metal complexes was studied. The APPA–NIPAAm copolymers with less than 11 mol % APPA moiety had a lower critical solution temperature (LCST) of approximately 45°C, but the APPA–NIPAAm copolymers with greater than 21 mol % APPA moiety had no LCST from 25 to 55°C. The APPA–NIPAAm copolymers had a higher adsorption capacity for Sm³⁺, Nd³⁺, and La³⁺ than for Cu²⁺, Ni²⁺ and Co²⁺. The APPA–NIPAAm (10:90) copolymer/metal (Sm³⁺, Nd³⁺, or La³⁺) complexes became water‐insoluble above 45°C at pH 6–7, but the APPA–NIPAAm (10:90) copolymer/metal (Cu²⁺,Ni²⁺, or Co²⁺) complexes were water‐soluble from 25 to 55°C at pH 6–7. The temperature at which both the APPA–NIPAAm copolymers and the copolymer/metal complexes became water‐insoluble increased as the pH values of the solutions increased. The APPA–NIPAAm copolymers were able to separate metal ions from their mixed solutions when the temperature of the solutions was changed; this was followed by centrifugation of the copolymer/metal complexes after the copolymers were added to the metal solutions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 116–125, 2004     

Chelation properties of poly(β‐diketone) polymer and its oxime toward heavy metal ions

The chelation behavior of poly(β‐diketone), polymer I, and poly(β‐diketone) oxime, polymer II, toward the divalent metal ions, Cu²⁺, Zn²⁺, Ni²⁺, and Cd²⁺, and the trivalent lanthanide metal ions, La³⁺, Nd³⁺, Sm³⁺, Gd³⁺, and Tb³⁺ was investigated by a batch equilibration technique as a function of contact time, pH, and counter ion. Polymer II exhibited improved chelation characteristics toward lanthanide metal ions in comparison with polymer I and the metal‐ion uptake follows the order Tb³⁺ ≈ Gd³⁺ ≈ Sm³⁺ > Nd³⁺ ≈ La³⁺. On the other hand, polymer I showed relatively higher capacity than polymer II, toward the investigated divalent metal ions, where the metal‐ion uptake follows the order Cu²⁺ > Cd²⁺ ≈ Zn²⁺ > Ni²⁺. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of NIPAAm-based polymer-grafted silica beads by surface-initiated ATRP using Me4Cyclam ligands and the thermo-responsive behaviors for lanthanide(III) ions

The applicability of atom transfer radical polymerization (ATRP) to the copolymerization of N-isopropylacrylamide (NIPAAm) with N-vinyl-2-pyrrolidone (NVP) was examined in CuCl/CuCl₂-catalyst system using tris[2-(dimethylamino)ethyl]amine (Me₆TREN) and 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (Me₄Cyclam) as ligands. In the Me₆TREN system, less reactive NVP not only does not quantitatively copolymerize but also interferes with homopolymerization of NIPAAm units. In contrast, the Me₄Cyclam system under heating was more active, although the controllability for polymer homogeneity is lower than Me₆TREN system. The application of active Me₄Cyclam system to surface-initiated ATRP has successfully prepared silica beads surface-modified with NIPAAm copolymers of NVP and 4-vinylpyridine (VPy). The thermo-responsive behavior of surface-grafted NIPAAm-based polymers was investigated for lanthanide trivalent ions (Ln(III)) in different pH solutions. In the weak acidic solutions of pH = 5.4–5.6, all the surface-grafted polymers including poly(NIPAAm) exhibited only adsorption behavior with regular selectivity (Eu³⁺ > Sm³⁺ > Nd³⁺ > Ce³⁺ > La³⁺) below the phase-transition temperatures. In the more acidic solution of pH = 2.9, the surface-grafted poly(NIPAAm) and NVP copolymers exhibited adsorption and desorption behaviors below and above the phase-transition temperatures, while VPy copolymers exhibited only adsorption independent of temperature change. Furthermore, the adsorption capacity of all the surface-grafted polymers was deteriorated by the lowering of pH. The observed desorption and the deterioration of adsorption capacity suggest the weakening of adsorption strength for Ln(III) in low pH solutions. In this study, a possible adsorption/desorption mechanism of Ln(III) on surface-grafted NIPAAm-based polymers is discussed.     

Synthesis of thermosensitive copolymer beads containing pyridinium groups and their antibacterial activity

Thermosensitive 4VP‐NIPAAm‐4G copolymer beads containing pyridyl groups were first prepared by suspension copolymerization of 4‐vinylpyridine (4VP), N‐isopropylacrylamide(NIPAAm), and tetraethylene glycol dimethacrylate (4G; crosslinking reagent) in a saturated Na₂SO₄ aqueous solution in the presence of surfactant and MgCO₃ as dispersants. Then the copolymer beads containing pyridinium groups were obtained by the quaternization of the copolymer beads with various alkyl iodides (CH₃I, C₄H₉I, C₈H₁₇I) in N,N‐dimethylformamide. The 4VP‐NIPAAm‐4G (15 : 97 : 3) copolymer bead and the 4VP‐NIPAAm‐4G copolymer beads quaternized with butyl iodide exhibited high thermosensitivity in water, although the 4VP‐NIPAAm‐4G copolymer beads quaternized with methyl iodide or octyl iodide hardly exhibited thermosensitivity. All the quaternized copolymer beads exhibited antibacterial activity against Escherichia coli (E. coli), although the 4VP‐NIPAAm‐4G copolymer bead did not. In particular, the copolymer bead quaternized with butyl iodide exhibited the highest antibacterial activity against E. coli at 30°C. It was also found that the antibacterial activity of the quaternized 4VP‐NIPAAm‐4G copolymer beads was greatly affected by not only chain length of alkyl groups in alkyl iodides, with which the 4VP‐NIPAAm‐4G copolymer beads were quaternized, but also by temperature of the solutions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Investigation of rare earth ions adsorption properties of PP‐g‐AA

Acrylic acid (AA) was grafted onto the powdered isotactic polypropylene (i‐PP) with the electron‐beam‐induced preirradiation method (Chen, D.‐T.; Shi, N.; Xu, D.‐F. J Appl Polym Sci 1999, 73, 1357–1362). Some rare earth ions, including Sm³⁺, Nd³⁺, Eu³⁺, Gd³⁺, and Er³⁺, were adsorbed onto the grafting product PP‐g‐AA. The properties of Sm³⁺ adsorbed were investigated in detail. These properties include the influences of the adsorption time, acidity, ion concentration of the solution, grafting yield of AA onto i‐PP, and temperature on the quantity and efficiency of the ion adsorption. Some kinetic and thermodynamic equilibrium constants of the adsorption were obtained in the experiments. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1549–1553, 2000     

CHELATION PROPERTIES OF POLY(8-HYDROXYQUINOLINE 5,7-DIYLMETHYLENE) TOWARDS SOME TRIVALENT LANTHANIDE METAL IONS

ABSTRACT

The sorption and desorption properties of the chelate-forming phenol-formaldehyde resin, poly(8-hydroxyquinoline 5,7-diylmethylene) towards various trivalent lanthanide ions such as La⁺³, Ce⁺³, Nd⁺³, Sm⁺³, and Gd⁺³ were studied by a static batch equilibration technique as a function of pH and contact time. The resin selectivity and binding capacity towards various lanthanide metal ions are discussed.     

Preparation of Chelating Resins Containing a Pair of Neighboring Carboxylic Acid Groups and the Adsorption Characteristics for Heavy Metal Ions

Abstract

For the functional enhancement of chelating resins containing carboxylic acids, copolymer beads were prepared by suspension polymerization of styrene (St), methyl methacrylate (MMA), and divinylbenzene (DVB) in the presence of toluene as diluent. The phenyl rings of the beads were directly chloromethylated, and the carboxylic ester groups of the beads were converted into hydroxymethyl groups by reduction followed by chlorination to give chloromethyl groups, respectively. The chelating resins containing a pair of neighboring carboxylic acid groups (NCAGs) were obtained by the alkylation of chloromethyl groups in copolymer beads with diethyl malonate in the presence of sodium hydride followed by hydrolysis using aqueous alkali solution. Accordingly, the structural effects of the resins on the adsorption of heavy metal ions were investigated. Poly(St‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb²⁺, Cd²⁺, and Cu²⁺, whereas poly(MMA‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Cu²⁺, Cd²⁺, and Co²⁺. On the other hand, poly(St‐co‐MMA‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb²⁺, Cd²⁺, Hg²⁺, Co²⁺, and Cu²⁺: a synergistic effect on the adsorption of heavy metal ions like Pb²⁺, Cd²⁺, Hg²⁺, and Co²⁺ was observed. The adsorption ability of poly(St‐co‐MMA‐co‐DVB)‐based chelating resin among three kinds of chelating resins was relatively good.     

Polypyrrole coated graphene nanoplatelets and the effect of rare earth ions with nanocomposites

PPy/graphene/rare earth ions (PPy/GR/La³⁺, PPy/GR/Sm³⁺, PPy/GR/Eu³⁺, PPy/GR/Gd³⁺ and PPy/GR/Tb³⁺) are fabricated via in-situ polymerization using p-toluenesulfonic acid as a dopant and FeCl₃ as an oxidant. The surface morphology of the PPy/GR/La³⁺, PPy/GR/Sm³⁺, PPy/GR/Eu³⁺, PPy/GR/Gd³⁺ and PPy/GR/Tb³⁺ composites were characterized by using transmission electron microscopy. The maximum conductivity of PPy/GR/La³⁺, PPy/GR/Sm³⁺, PPy/GR/Eu³⁺, PPy/GR/Gd³⁺ and PPy/GR/Tb³⁺ composites found with 1 wt.% GR and 2 wt.% La³⁺, Sm³⁺, Eu³⁺, Gd³⁺ and Tb³⁺ at room temperature.     

Response of Nd3+ and Sm3+ precipitating into rhabdophane and the leaching mechanism of associated monazite ceramics

Rhabdophane has been considered an important permeable reactive barrier to isolate groundwater radionuclides, and evaluating its precipitation response to different species of radionuclide in acid solutions is critical. In this work, the effects of pH values on the precipitation behavior of Nd³⁺ and Sm³⁺ into La-rhabdophane are systematically investigated. Some specific issues such as ions removal, precipitation reaction kinetics, and crystal growth affected ions incorporation are discussed in detail, along with uncovering the veil of the Ln (La, Nd, and Sm) leaching mechanism of associated La_0.666Nd_0.167Sm_0.167PO₄ monazite ceramic based on dissolution experiments and density functional theory. The results reveal that Nd³⁺ and Sm³⁺ can be removed more than 98% in pH = 1 solution within 12 h, whereas uneven precipitation process to form unexpected stoichiometric ratio of rhabdophane has been observed in 30–50 nm short crystal. Grain growth effects based on spark plasma sintering can contribute to homogenize the materials composition with obtaining La_0.666Nd_0.167Sm_0.167PO₄ monazite ceramics. Furthermore, the binding energy of Ln–O in (1 0 0) surface of monazite plays an important role in controlling the leaching stability of Ln³⁺, associated with the leaching activities are energetically favorable in the order of La > Nd > Sm for La_0.666Nd_0.167Sm_0.167PO₄ monazite.     

Study on the adsorption–desorption behaviours of La3+, Sm3+, and Y3+ by HEHEHP extraction resin in chloride medium

The adsorption–desorption behaviours of La³⁺, Sm³⁺, and Y³⁺ on 2-ethylhexylphosphonic acid mono-2-ethyl hexyl ester (HEHEHP) extraction resin were investigated in a chloride medium. The effects of reaction time, pH, hydrochloric acid concentration, flow rate, and adsorption mechanism were studied in detail using static and dynamic experimental methods. The results show that La³⁺ is the first to reach adsorption equilibrium, followed by Sm³⁺ and Y³⁺; the highest adsorption capacities of La³⁺, Sm³⁺, and Y³⁺ are obtained at solution pH of 4 and in the order of Y³⁺ > Sm³⁺ > La³⁺. La³⁺, Sm³⁺, and Y³⁺ can be eluted by 0.3, 0.5, and 3 mol/L hydrochloric acid, respectively, indicating that La³⁺ elutes most easily, and Y³⁺ is difficult. Moreover, the flow rate has little effect on the peak of rare earth desorption. The adsorption process is chemisorption; the slope method indicates that for each mol Sm³⁺ or Y³⁺ ion adsorbed, 3 mol H⁺ ions are simultaneously released, but two for La³⁺ under the given pH conditions. It is expected to provide theoretical and technical support for preparation of ultra-high purity rare earth by HEHEHP extraction resin.     

Synthesis and heavy metal ion adsorptivity of macroreticular chelating resins containing phosphono and carboxylic acid groups

Macroreticular copolymer beads were prepared by suspension polymerization of 4-vinylbenzyl chloride (VBC), divinylbenzene (DVB) and monomers with carboxylic ester groups like dibutyl maleate (DBM), dibutyl fumarate (DBF) and dibutyl itaconate (DBI) in the presence of toluene as diluent. The copolymer beads were phosphorylated at the chloromethylated phenyl rings with triethyl phosphite and hydrolyzed by an aqueous sodium hydroxide solution; the hydrolysis on the bead surface converted carboxylic ester/phosphonate groups into carboxylic acid/phosphono groups, respectively. The investigations on the metal ion chelation characteristics of the H-form copolymer beads revealed that they have good adsorptivity toward heavy metal ions like Pb²⁺, Cd²⁺ and Cu²⁺, and poor adsorptivity toward ions like Hg²⁺ and UO₂²⁺. The adsorptivity caused by the three carboxylic ester monomer derivatives was in the order DBM > DBI > DBF. Especially, the Na-form copolymer beads neutralized by alkali treatment were very available for the adsorption of all the metal ions under investigation.     

A fluorescent probe for the determination of Ce4+ in aqueous media

A rhodamine-based probe bearing an N,N-dimethylaniline unit was developed as a fluorescent chemodosimeter for Ce⁴⁺ in aqueous media. Importantly, the sensor can selectively respond to Ce⁴⁺ over other commonly coexistent metal ions (such as La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Er³⁺, Tb³⁺, Ho³⁺, Tm³⁺, Yb³⁺, Lu³⁺, Y³⁺) in aqueous media with a rapid response time. The system, which utilizes an irreversible Ce⁴⁺-promoted oxidation reaction, responds instantaneously at room temperature with linear proportionality to the amount of Ce⁴⁺.     

The Separation of Am from Lanthanides by Purified Cyanex 301 Extraction

Abstract

Separation factors of tracer amounts of Am from micro lanthanides (La, Ce, Pr, Nd, and Sm) by purified Cyanex 301 extraction in nitrate media have been determined: SF_Am/La ～ 3500, SF_Am/Ce,pr ～ 1000, SF_Am/Nd ～ 1900, and SF_Am/Sm～ 4500, with an average value >2300. The distribution ratio decreases with increasing lanthanide concentration in the aqueous phase. In the presence of a macro amount of Pr + Nd (0.1 ～ 0.6 M) the separation factors SF_Am/Eu and SF_Am/pr+Ndare about 4.7 × 10³ and 2.1 × 10³, respectively. The results of the countercurrent fractional process show that by using three extraction stages and two scrubbing stages, >99.99% Am can be separated from a tracer amount of Eu with <0.1% extraction of Eu. Using six extraction stages, >99.99% Am and <0.6% macro amount of Pr ± Nd are extracted into the organic phase.     

Chiral ternary lanthanide complexes of 2-mercaptosalicylic acid

New ternary complexes of the types Ln(phen)L₃ and Ln(bipy)L₃ (phen=1,10-phenanthroline, bipy=2,2′-bipyridine; L=2-mercaptosalicylic acid; Ln=La³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Ho³⁺, Yb³⁺) have been synthesized and characterized by elemental analysis, molar conductance, CD, XPS, IR, ¹H NMR (DMF-d₇) and electronic spectra.     

Dual-phase rare-earth-zirconate high-entropy ceramics with glass-like thermal conductivity

A series of rare earth zirconates (RE₂Zr₂O₇) high-entropy ceramics with single- and dual-phase structure were prepared. Compared with La₂Zr₂O₇ and Yb₂Zr₂O₇, the smaller “rattling” ions (Yb³⁺, Er³⁺, Y³⁺) have been incorporated into pyrochlore lattice in (La_0.2Nd_0.2Y_0.2Er_0.2Yb_0.2)₂Zr₂O₇ (LNYEY) while larger ions (La³⁺, Nd³⁺, Sm³⁺, Eu³⁺) incorporated into fluorite lattice in (La_0.2Nd_0.2Sm_0.2Gd_0.2Yb_0.2)₂Zr₂O₇ (LNSGY). Due to high-entropy lattice distortion and resonant scattering derived from smaller ions Yb³⁺, Er³⁺, and Y³⁺, LNYEY shows a lower glass-like thermal conductivity (1.62-1.59 W m^-1 K^-1, 100-600℃) than LNSGY (1.74-1.75 W m^-1 K^-1, 100-600℃). Moreover, LNYEY and LNSGY exhibit enhanced Vickers’ hardness (LNYEY, H_v = 11.47 ± 0.41 GPa; LNSGY, H_v = 10.96 ± 0.26 GPa) and thermal expansion coefficients (LNYEY, 10.45 × 10^-6 K^-1, 1000℃; LNSGY, 11.02 × 10^-6 K^-1, 1000℃). These results indicate that dual-phase rare-earth-zirconate high-entropy ceramics could be desirable for thermal barrier coatings.     

Microstructure of Eu3+‐Doped Perovskites‐Type Niobate Ceramic La3Mg2NbO9

Eu³⁺‐doped red‐emitting ceramics of Eu³⁺‐doped La₃Mg₂NbO₉ were prepared via typical solid state. X‐ray diffraction and scanning electron microscope were utilized to characterize the ceramics. The photoluminescence excitation and emission spectra, the fluorescence decay curves, and color coordinates were investigated. The concentration quenching of the samples were discussed as well. The microstructures of the ceramics were discussed according to the spectral properties of probe ions of Eu³⁺, for example, substitution sites for Eu³⁺, inhomogeneous broadening and splitting of the emission bands, nonexponential decay, ⁵D₀→⁷F₀ emission transition, distorted symmetry sites, etc. The crystal structure of La₃Mg₂NbO₉ is heavily distorted due to the mixed occupation of Mg and Nb on B sites. Eu³⁺ ions only substitute La³⁺ sites and Eu³⁺ ions (or rare‐earth ions) are arranged in the heavily disordered environments over the whole structure in La₃Mg₂NbO₉.     

Removal of heavy‐metal ions by magnetic beads containing triazole chelating groups

The aim of this study was to prepare magnetic beads that could be used for the removal of heavy‐metal ions from synthetic solutions. Magnetic poly(ethylene glycol dimethacrylate–1‐vinyl‐1,2,4‐triazole) [m‐poly(EGDMA–VTAZ)] beads were produced by suspension polymerization in the presence of a magnetite Fe₃O₄ nanopowder. The specific surface area of the m‐poly(EGDMA–VTAZ) beads was 74.8 m²/g with a diameter range of 150–200 μm, and the swelling ratio was 84%. The average Fe₃O₄ content of the resulting m‐poly(EGDMA–VTAZ) beads was 14.8%. The maximum binding capacities of the m‐poly(EGDMA–VTAZ) beads from aquous solution were 284.3 mg/g for Hg²⁺, 193.8 mg/g for Pb²⁺, 151.5 mg/g for Cu²⁺, 128.1 mg/g for Cd²⁺, and 99.4 mg/g for Zn²⁺. The affinity order on a mass basis was Hg²⁺ > Pb²⁺ > Cu²⁺ > Cd²⁺> Zn²⁺. The binding capacities from synthetic waste water were 178.1 mg/g for Hg²⁺, 132.4 mg/g for Pb²⁺, 83.5 mg/g for Cu²⁺, 54.1 mg/g for Cd²⁺, and 32.4 mg/g for Zn²⁺. The magnetic beads could be regenerated (up to ca. 97%) by a treatment with 0.1M HNO₃. These features make m‐poly(EGDMA–VTAZ) beads potential supports for heavy‐metal removal under a magnetic field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation,luminescence properties and energy transfer of Ca9Y(PO4)7: Eu2+‐Tb3+ phosphors

Tb³⁺‐doped and Eu²⁺, Tb³⁺ co‐doped Ca₉Y(PO₄)₇ phosphors were synthesized by conventional solid‐state method. Additionally, the luminescence properties, decay behavior and energy transfer mechanism have already been investigated in detail. The green emission intensity of Tb³⁺ ions under NUV excitation is weak due to its spin‐forbidden f‐f transition. While Eu²⁺ can efficiently absorb NUV light and yield broad blue emission, most of which can be absorbed by Tb³⁺ ions. Thus, the emission color can be easily tuned from cyan to green through the energy transfer of Eu²⁺→Tb³⁺ in Ca₉Y(PO₄)₇:Eu²⁺,Tb³⁺ phosphor. In this work, the phenomenon of cross‐relaxation between ⁵D₃ and ⁵D₄ are also mentioned. The energy transfer is confirmed to be resulted from a quadrupole‐quadrupole mechanism.     

ONIOM Study for Selectivity of Extractants for Extraction of Rare‐Earth Metals

A hybrid molecular modelling technique, the ONIOM method, has been used to study the selectivity of various extractants for the extraction of La³⁺ and Nd³⁺. MM calculations have been done for the environmental system, whereas DFT calculation has been carried out for the model system. The total ONIOM energy of the metal‐ligand complexes was calculated and the selectivity of La³⁺ and Nd³⁺ for D2EPHA, Cyanex 272 as well as PC88A determined based on the interaction energy. The lower energy for Nd complexes compared to La complexes for all three extractants shows preference of Nd over La. The ONIOM calculations infer the stability of the metal complexes in the order of D2EPHA >PC88A >Cyanex 272, which agrees well with the experimental results for both metal ions.     

Electrical and thermophysical properties of mechanochemically obtained lanthanide hafnates

This contribution presents the synthesis and thermophysical characterization of seven lanthanide hafnates Ln₂Hf₂O₇ (Ln=Sm³⁺, Eu³⁺, Gd³⁺, Dy³⁺, Y³⁺, Ho³⁺, Yb³⁺); the title samples were prepared at room temperature by mechanically milling stoichiometric mixtures of the corresponding elemental oxides. Irrespective of the lanthanide ion involved, milling promotes the formation of highly disordered fluoritelike materials. Postmilling thermal treatments facilitate the formation of the fluorite ordered derivative, the pyrochlore structure, but only for the larger lanthanides (Sm³⁺, Eu³⁺, Gd³⁺). Impedance spectroscopy measurements revealed that these materials show a moderate‐to‐good oxygen ion conductivity at high temperatures; furthermore, those adopting the pyrochlore structure give higher σ_dc and lower E_dc than their fluorite analogues (σ_dc at 750°C>10^?3 S·cm^?1 vs <5·10^?4 S·cm^?1, respectively). The same trend also holds for the thermal resistivity at high temperatures; the highest thermal resistivity and thus, lowest κ was obtained for Eu₂Hf₂O₇ (κ~1.3·W·m^?1·K^?1 at 800°C). Therefore, Ln₂Hf₂O₇ phases might be attractive component materials for electrochemical devices and thermal insulating coatings.