Solvent impregnated resin prepared using task-specific ionic liquids for rare earth separation

A novel bifunctional task-specific ionic liquid (TSIL), i.e. [trialkylmethylammonium][sec-nonylphenoxy acetate] ([A336] [CA-100]) was impregnated on intermediate polarized XAD-7 resin, and the prepared solvent impreganated resin (SIR) was studied for rare earth (RE) separation. Adsorption ability of the SIR was indicated to be obviously higher than that prepared by [A336][NO3] because of the functional anion of [A336][CA-100]. Adsorption kinetics, adsorption isotherm, separation and desorption of the SIR were also studied.

Five supramolecular compounds of water-soluble sulfonylcalix[4]arenetetrasulfonate showing two calixarene conformations

Five new compounds of sulfonylcalix[4]arenetetrasulfonate (SC4AS), [H7Na(H2O)(3)(SC4AS)(phen)(5)](H2O)(11.9) (1), [H6Mn(H2O)(4)(SC4AS)(phen)(5)] (H2O)(12.7) (2), [Cu-4(SC4AS) (phen)(6)] (H2O)(4.5) (3), {[Cu (2)(SC4AS) (bpy)(2)][Cu(bpy)(2)(H2O)](2)} (H2O)(6.6) (4), and {[Zn-2(SC4AS) (phen)(2)][Zn(phen)(2)(H2O)(2)](2)} (H2O)(7) (5) (where phen 1,10-phenanthroline and bpy = 2,2'-bipyridine), were synthesized by a hydrothermal method and structurally determined by single crystal X-ray diffraction. The SC4AS ligand adopts partial cone conformation in compounds 1 and 2 and 1,2-alternate form in compounds 3-5. According to the structural analysis and density functional theory (DFT) calculations, we suggest that the metal can affect the conformation of SC4AS.

Multiform oxide optical materials via the versatile Pechini-type sol-gel process: Synthesis and characteristics

This feature article highlights work from the authors' laboratories on the various kinds of oxide optical materials, mainly luminescence and pigment materials with different forms (powder, core-shell structures, thin film and patterning) prepared by the Pechini-type sol-gel (PSG) process. The PSG process, which uses the common metal salts (nitrates, acetates, chlorides, etc.) as precursors and citric acid (CA) as chelating ligands of metal ions and polyhydroxy alcohol (such as ethylene glycol or poly ethylene glycol) as a cross-linking agent to form a polymeric resin on molecular level, reduces segregation of particular metal ions and ensures compositional homogeneity. This process can overcome most of the difficulties and disadvantages that frequently occur in the alkoxides based sol-gel process.

Direct toxicity assessment of toxic chemicals with electrochemical method

Electrochemical measurement of respiratory chain activity is a rapid and reliable screening for the toxicity on microorganisms. Here, we investigated in-vitro effects of toxin on Escherichia coli (E. coli) that was taken as a model microorganism incubated with ferricyanide. The current signal of ferrocyanide effectively amplified by ultramicroelectrode array (UMEA), which was proven to be directly related to the toxicity. Accordingly, a direct toxicity assessment (DTA) based on chronoamperometry was proposed to detect the effect of toxic chemicals on microorganisms. The electrochemical responses to 3,5-dichlorophenol (DCP) under the incubation times revealed that the toxicity reached a stable level at 60 min, and its 50% inhibiting concentration (IC50) was estimated to be 8.0 mg L-1. At 60 min incubation, the IC50 values for KCN and As2O3 in water samples were 4.9 mg L-1 and 18.3 mg L-1, respectively. But the heavy metal ions, such as Cu2+ Pb2+ and Ni2+, showed no obvious toxicity on E. coli.

Combining chemical reduction with an electrochemical technique for the simultaneous detection of Cr(VI), Pb(II) and Cd(II)

This work herein reports the approach for the simultaneous determination of heavy metal ions including cadmium (Cd(II)), lead (Pb(II)), and chromium (Cr(VI)) using a bismuth film electrode (BFE) by anodic stripping voltammertry (ASV). The BFE used was plated in situ. Due to the reduction of Cr(VI) with H2O2 in the acid medium, on one hand, the Cr(III) was produced and Cr(VI) was indirectly detected by monitoring the content of Cr(III) using square-wave ASV. On the other hand, Pb(II) was also released from the complex between Pb(II) and Cr(VI). Furthermore, the coexistence of the Cd(II) was also simultaneously detected with Pb(II) and Cr(VI) in this system as a result of the formation of an alloy with Bi. The detection limits of this method were 1.39 ppb for Cd(II), 2.47 ppb for Pb(II) and 5.27 ppb for Cr(VI) with a preconcentration time of 120 s under optimal conditions (S/N = 3), respectively. Furthermore, the sensitivity of this method can be improved by controlling the deposition time or by using a cation-exchange polymer (such as Nafion) modified electrode.

Ionic liquids used in and analyzed by capillary and microchip electrophoresis

This review, covering reports published from 2001 to December 2008, shows how ionic liquids (ILs) have made significant contributions in the improvement of capillary and microchip electrophoresis (CE and mu CE) for the separation and detection of analytes such as phenols and aromatic acids, metal ions, medicines, enantiomers. biological materials, etc. Furthermore, CE methods applied in the sensitive and accurate determination of physico-chemical properties of ILs have been summarized. Accordingly, research vacancies and future development trends in these areas are discussed.

Direct synthesis of ordered N-methylimidazolium functionalized mesoporous silica as highly efficient anion exchanger of Cr(VI)

Ordered N-methylimidazolium functionalized mesoporous silica (SBA-15) anion exchangers were directly synthesized by co-condensation of tetraethoxysilane with 1-methyl-3(triethoxysilylpropyl)imidazolium chloride. The prepared samples with rod-like morphology showed high surface areas (> 400 m(2) g(-1)), well-ordered pores (> 58 angstrom), and excellent thermal stability up to 387 degrees C. The adsorption behaviors of Cr(VI) from aqueous solution on the anion exchangers were studied using the batch method. The anion exchangers had high adsorption capacity ranging from 50.8 to 90.5 mg g(-1), over a wider pH range (1-8) than amino functionalized mesoporous silica. The adsorption rate was fast, and the maximum adsorption was obtained at pH 4.6. The adsorption data for the anion exchangers were consistent with the Langmuir isotherm equation. Most active sites of the anion exchangers were easily accessible. The mixed solution of 0.1 mol L-1 NH3 center dot H2O and 0.5 mol L-1 NH4Cl was effective desorption solution, and 95% of Cr(VI) could be desorbed.

Templated assembly of mu(5)-CO32- decanuclear praseodymium and neodymium clusters through spontaneous fixation of atmospheric carbon dioxide

Reactions of Ln(III) acetate (Ln = Pr and Nd) and a polydentate Schiff-base in a mixture of methanol and acetonitrile resulted in the unprecedented assembly of novel Ln(10) aggregates containing two Ln(5) pentagons templated by mu(5)-CO32-, introduced via spontaneous fixation of atmospheric carbon dioxide. Magnetic analysis using an expression including the ligand field effects and molecular field approximation indicates weak antiferromagnetic coupling between the metal ions. This synthetic approach may represent a promising new route toward the design of new lanthanide clusters and novel multifunctional materials.

Extraction and recovery of cerium(IV) along with fluorine(I) from bastnasite leaching liquor by DEHEHP in [C(8)mim]PF6

BACKGROUND: Ionic liquids (ILs) as environmentally benign solvents have been widely studied in the application of solvent extraction. However, few applications have been successfully industrialized because of the difficult stripping of metal ions or the loss of components of the ILs. More work needs to be done to investigate the extraction behaviour of IL-based extraction systems. In this work, the extraction behaviour of Ce(IV), Th(IV) and some trivalent rare earth (RE) nitrates by di(2-ethylhexyl) 2-ethylhexylphosphonate (DEHEHP) in the IL, 1-methyl-3-octylimidazolium hexafluorophosphate ([C(8)mim]PF6), was investigated and compared with that in the n-heptane system. In particular, the effect of F(I) on the extraction mechanism for Ce(IV) and its separation from Th(IV) was investigated. Otherwise, the recovery efficiency of Ce(IV) and F(I) from a practical bastnasite leach liquor was examined using IL based extraction.

Label-Free Colorimetric Detection of Aqueous Mercury Ion (Hg2+) Using Hg2+-Modulated G-Quadruplex-Based DNAzymes

Mercury ion (Hg2+) is able to specifically bind to the thymine-thymine (T-T) base pair in a DNA duplex, thus providing a rationale for DNA-based selective detection of Hg2+ with various means. In this work, we for the first time utilize the Hg2+-mediated T-T base pair to modulate the proper folding of G-quadruplex DNAs and inhibit the DNAzyme activity, thereby pioneering a facile approach to sense Hg2+ with colorimetry. Two bimolecular DNA G-quadruplexes containing many T residues are adopted here, which function well in low- and high-salt conditions, respectively. These G-quadruplex DNAs are able to bind hemin to form the peroxidase-like DNAzymes in the folded state. Upon addition of Hg2+, the proper folding of G-quadruplex DNAs is inhibited due to the formation of T-Hg2+-T complex. Ibis is reflected by the notable change of the Soret band of hemin when investigated by using UV-vis absorption spectroscopy. As a result of Hg2+ inhibition, a sharp decrease in the catalytic activity toward the H2O2-mediated oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) is observed, accompanied by a change in solution color. Through this approach, aqueous Hg2+ can be detected at 50 nM (10 ppb) with colorimetry in a facile way, with high selectivity against other metal ions.

7-Amino actinomycin D bound to single-stranded hairpin DNA enhanced by loop sequence-dependent luminescent Eu3+ and Tb3+ binding

Lanthanide Eu3+ and Tb3+ ions have been widely used in luminescent resonance energy transfer (LRET) for bioassays to study metal binding microenvironments. We report here that Eu3+ or Tb3+ can increase the binding affinity of antitumor antibiotic drug agent, 7-amino actinomycin D (7AACTD), binding to 5'-GT/TG-5' or 5'-GA/AG-5' mismatched stem region of the single-stranded hairpin DNA. Further studies indicate that the effect of Eu3+ or Tb3+ on 7AACTD binding is related to DNA loop sequence. Our results will provide new insights into how metal ions can enhance antitumor agents binding to their targets.

Tunable luminescence properties of Tb3+-doped LaGaO3 nanocrystalline phosphors

Nanocyrstalline Tb3+-doped LaGaO3 phosphors were prepared through a Pechini-type sol-gel process. X-ray diffraction, field-emission scanning electron microscopy (FESEM), photoluminescence, cathodoluminescence spectra, and lifetimes were utilized to characterize the synthesized phosphors. XRD results reveal that the sample begins to crystallize at 900 degrees C and pure LaGaO3 phase can be obtained at 1000 degrees C. FESEM images indicate that the Tb3+-doped LaGaO3 phosphors are composed of aggregated spherical particles with sizes ranging from 40 to 80 nm. Under the excitation of ultraviolet light and low-voltage electron beams (0.5-3 kV), the Tb3+-doped LaGaO3 phosphors show the characteristic emissions from the LaGaO3 host lattice and the Tb3+ (D-5(3,4)-F-7(6,5,4,3) transitions). The emission colors of Tb3+-doped LaGaO3 phosphors can be tuned from blue to green by changing the excitation wavelength of ultraviolet light and the doping concentration of Tb3+ to some extent. Relevant luminescence mechanisms are discussed.

The preparation of sol-gel materials doped with ionic liquids and trialkyl phosphine oxides for Yttrium(III) uptake

A new material (IL923SGs) composed of ionic liquids and trialkyl phosphine oxides (Cyanex 923) for Y(III) uptake was prepared via a sol-gel method. The hydrophobic ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate (C(8)mim(+)PF(6)-) was used as solvent medium and pore templating material. The extraction of Y(III) by IL923SGs was mainly due to the complexation of metal ions with Cyanex 923 doped in the solid silica. Ionic liquid was stably doped into the silica gel matrix providing a diffusion medium for Cyanex 923, and this will result in higher removal efficiencies and excellent stability for metal ions separation. IL923SGs were also easily regenerated and reused in the subsequent removal of Y(III) in four cycles.

Templated synthesis of composite rings using core-shell toroids

In difference to compact objects of a similar size, toroidal structures have some distinguishing properties that originate from their open inner cavity and closed circuit. Here, a general facile methodology is developed to prepare composite rings with varied compositions on a large scale by using core-shell toroids assembled from tri-block copolymers of poly(4-vinyl pyridine) (PVP)/polystyrene (PS)/PVP. Taking advantage of the complexation ability of the PVP shell, varied components that range from polymers, inorganic materials, metals and their compounds, as well as pre-formed nanoparticles are introduced to the toroidal structures to form composite nanostructures. Metal ions can be adsorbed by PVP through complexation. After in situ reduction, a large number of metal-based functional materials can be prepared. PVP is alkaline, and thus capable of catalyzing the sol-gel process to generate an inorganic shell. Furthermore, pre-formed nanoparticles can also be absorbed by the shell through specific interactions. The PS core is not infiltrative during synthesis, and hollow rings can be derived after the polymer templates are removed.

Extraction and separation of cadmium(II), iron(III), zinc(II), and europium(III) by Cyanex302 solutions using hollow fiber membrane modules

The mass transfer behaviors of Cd(II), Fe(III), Zn(II), and Eu(III) in sulfuric acid solution using microporous hollow fiber membrane (HFM) containing bis(2,4,4-trimethylpentyl)monothiophosphinic acid (commercial name Cyanex302) were investigated in this paper. The experimental results showed that the values of the mass transfer coefficients (K-w) decreased with an increase of H+ concentration and increased with an increase of extractant Cyanex302 concentration. The mass transfer resistance of Eu3+ was the largest because K-w value of Eu3+ was the smallest. The order of mass transfer rate of metal ions at low pH was Cd > Zn > Fe > Eu. Mixtures of Zn2+ and Eu3+ or of Zn2+ and Cd2+ were well separated in a counter-current circulation experiment using two modules connected in series at different initial acidity and concentration ratio. These results indicate that a hollow fiber membrane extractor is capable of separating the mixture compounds by controlling the acidity of the aqueous solution and by exploiting different mass transfer kinetics. The interfacial activity of Cyanex302 in sulfuric acid solution was measured and interfacial parameters were obtained according to Gibbs adsorption equation.