Synthesis of 4-acylpyrazolone Schiff base ligand grafted silica and selectivity in adsorption of lanthanides from aqueous solutions

The Schiff base form of the 4-acylpyrazolone ligand was immobilized on the silica surface by reaction of 3-aminopropyl silica with 4-acetyl-5-methyl-2-phenyl-2,4-dihydro-pyrazol-3-one in 97% yield, producing grafted silica with 0.77 mmol/g ligand loading. This surface modified silica was shown to be selective in the adsorption of Yb3+ ions from dilute aqueous solutions, for which 98% adsorption was observed from a 1.0×10-5 mol/L aq. solution at pH 6.7, after 24 h at room temperature. Six other lanthanides studied Eu3+, Gd3+, Nd3+, Tb3+, Sm3+ and La3+ showed moderate to weaker adsorptions of 39%, 28%, 16%, 12%, 11% and 5% respectively under similar conditions.

Investigation of Interaction of Lanthanides with Hemoglobin and Effect on Oxygen-Carier Function

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Solvent Extraction of Some Lanthanides with Trioctylphosphine Oxide in Molten Paraffin Wax

The extraction behavior of Ln(Ⅲ) (Ln=Nd, Sm, Tb and Yb) with trioctylphosphine oxide (TOPO) in molten paraffin wax has been studied. The effect of pH, TOPO concentration, medium, stirring time and the amount of salts added on the distribution of lanthanides between two phases were investigated. Two different compositions Ln(H2O)s-2 (TOPO)2(OH)2NO3 (Ln=Nd and Sm) and Ln(H2O)s-1(TOPO)2(OH) (NO3)2 (Ln=Tb and Yb) were determined by slope analysis method. The equilibrium extraction constant Kex and PH1/2 value were calculated and the thermodynamic parameters were obtained from the dependence of Kex on the temperature.

Synergistic Extraction of Lanthanides by 1-Nitroso-2-Naphthol and Trioctylphosphine Oxide in Paraffin Wax

The paraffin wax was used as a diluent for 1-nitroso-2-naphthol（HA） and trioctylphosphine oxide（TOPO） in the extraction of lanthanides at 70℃. The composition of the extracted species was given as LnA3（TOPO）2 by means of the slope analysis. The variation of the synergistic extraction equilibrium constant（K sex） was investigated at 60～80℃, and the thermodynamic data were calculated. The dependence of separation factors on temperature was also studied.

Determination of Lanthanides, Thorium, Uranium and Plutonium in Irradiated (Th, Pu)O_(2) by Liquid Chromatography Using α-Hydroxyiso Butyric Acid (α-HIBA)

An HPLC method is presented for the separation and determination of lanthanides (Lns), thorium (Th), uranium (U) and plutonium (Pu) from irradiated (Th, Pu)O2. Individual separation of Lns, Th, U and Pu is a challenging task becauseof 1) lanthanideshavingsimilar physical and chemical properties, 2) presence of complex matrix like irradiated fuel and 3) the co-existence of multiple oxidation states of Pu. Different procedures were developed for separation of individual lanthanides and actinides.The individual lanthanides were separated on a dynamically modified reversed phase (RP) column using n-octane sulfonic acid as an ion interaction reagentand employingdual gradient(pH and concentration) of α-hydroxyisobutyric acid (HIBA). In order to improve the precision on the determination of Lns, terbium (Tb) was used as an internal standard. The method was validated employing simulated high level liquid waste. Concentrations of lanthanides viz. lanthanum (La) and neodymium (Nd) in the dissolver solution were determined based on their peak areas. Th, U and Pu were separated on a RP column using mobile phase containing HIBA and methanol. Since Pu is prone to exist in multiple oxidation states, all the oxidation states were converted into Pu (IV) using H2O2 in 3M HNO3. Under the optimized conditions, Pu(IV) eluted first followed by Th and U. The concentrations of Th, U and Pu were determined by standard addition method andwere found to be 1.10 ± 0.02 mg/g, 5.3 ± 0.3 μg/g and 27 ± 1 μg/g, respectively, in the dissolver solution of irradiated fuel. These values were in good agreement with the concentration of Th determined by biamperometry and those of U and Puby isotope dilution thermal ionization mass spectrometry.

Enrichment of lanthanides in aragonite

Using the constant addition technique,the coprecipitation of lanthanum,gadolinium,and lutetium with aragonite in seawater was experimentally investigated at 25 ℃.Their concentrations in aragonite overgrowths were determined by inductive coupled plasma mass spectrometer.All these lanthanides were strongly enriched in aragonite overgrowths.The amount of lanthanum,gadolinium,and lutetium incorporated into aragonite accounted for 57%-99%,50%-89%,and 40%-91% of their initial total amount,respectively.With the increase of aragonite precipitation rate,more lanthanides were incorporated into aragonite while their relative fraction in aragonite overgrowths decreased consistently.It indicated that the coprecipitation of lanthanides with aragonite was controlled by the kinetics of aragonite precipitation.

SOLVENT EXTRACTION OF LANTHANIDES IN AQUEOUS NITRITE MEDIA BY CYANEX 302

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Separation of Americium from Fission Product Lanthanides Using Cyanex 301 Extraction

The extraction behavior of bis (2,4,4-trimethylpentyl) dithiophosphinic acid (HBTMPDTP), purified from Cyanex 301, was studied for extracting Am 3+ and trivalent lanthanides (Lns). HBTMPDTP shows very high selectivity for Am. Separation factor (SF) of Am and Eu, SF Am/Eu ,(trace amount) reaches a high value of 5.9×10 3 and SF Am/(Pr+Nd) (macro amount) is about 2×10 3. The mathematical model for the distribution ratios and process parameters calculated for HBTMPDTP extraction was established and the calculated results were verified experimentally. In a five-stage countercurrent process, the extraction rates of Am and Lns were > 99.999% and 0.14%, respectively, to fulfill the separation requirements. The efficiency of this process was also verified in a cross-flow extraction experiment using a genuine Am-FPLns fraction. In the presence of TBP, the extraction of Am and Eu is enhanced, but their separation is reduced to some extent. A fairly good separation was achieved in a fractional extraction process using a mixture of HBTMPDTP and TBP in kerosene at low pH.

Nucleotide coordination with 14 lanthanides studied by isothermal titration calorimetry

With their hydrolytic, optical and magnetic properties, lanthanide ions(Ln^(3+)) are versatile probes for nucleic acids. In addition, nucleotide-coordinated Ln^(3+) ions form useful nanoparticles. However, the thermodynamic basis of their interaction is still lacking. In this work, isothermal titration calorimetry(ITC) is used to study the binding between nucleotides and 14 different Ln^(3+) ions. Ln^(3+) interacts mainly with the phosphate of cytidine and thymidine monophosphate(CMP and TMP), while the nucleobases in adenosine and guanosine monophosphate(AMP and GMP) are also involved. Phosphate binding is fully entropy driven since the reactions absorb heat. Nucleosides alone do not bind Ln^(3+) and the purines need the phosphate for chelation. With increasing atomic number of Ln^(3+), the binding reaction with GMP goes from exothermic to endothermic. The entropy contribution starts to increase from Gd^(3+), explaining the'gadolinium break' observed in many Ln^(3+)-mediated RNA cleavage reactions. This study provides fundamental insights into the Ln^(3+)/nucleotide interactions, and it is useful for understanding related biosensors, nanomaterials, catalysts, and for lanthanide separation.

Column leaching of lanthanides from Abu Tartur phosphate ore with kinetic study

The dynamic leaching of lanthanides from a west desert phosphate ore, Egypt (Abu Tartur) by hydrochloric acid, nitric acid and sulfuric acid solutions was investigated in this study as a function of acid concentration, flow rate and the presence of some additives such as boric acid. Also the kinetics of leaching of lanthanides was investigated as a function of temperature. It was found that the leaching process could be described by a shrinking-core model, with activation energy about 5.9, 13.8 and 21.9 kJ/M for leaching by HCl, HNO3 and H2SO4, respectively. Based on the experimental results, an empirical equation related to the rate constant of lanthanides leaching to leaching temperature was established for the purpose of process design.

Efficient separation between trivalent americium and lanthanides enabled by a phenanthroline-based polymeric organic framework

Separation of the minor actinides(Am and Cm)from lanthanides in high-level liquid wastes(HLLW)is one of the most challenging chemical separation tasks known owing to their chemical similarities and is highly significant in nuclear fuel reprocessing plants because it could practically lead to sustainable nuclear energy by closing the nuclear fuel cycle.The solid phase extraction is proposed to be a possible strategy but all reported sorbent materials severely suffer from limited stability and/or efficiency caused by the harsh conditions of high acidity coupled with intense irradiation.Herein,a phenanthroline-based polymeric organic framework(PhenTAPB-POF)was designed and tested for the separation of trivalent americium from lanthanides for the first time.Due to its fully conjugated structure,PhenTAPB-POF exhibits previously unachieved stability under the combined extreme conditions of strong acids and high irradiation field.The americium partitioning experiment indicates that PhenTAPB-POF possesses an ultrahigh adsorption selectivity towards Am(Ⅲ)over lanthanides(e.g.,SFAm(Ⅲ)/Eu(Ⅲ)=3326)in highly acidic simulated HLLW and relatively fast adsorption kinetics in both static and dynamic experiments.Am(Ⅲ)can be almost quantitatively eluted from the PhenTAPB-POF packed-column using a concentrated nitric acid elution.The high stability and superior separation performance endow PhenTAPB-POF with the promising alternative for separating minor actinides over lanthanides from highly acidic HLLW streams.

Evaluation of toxicity profiles of rare earth elements salts(lanthanides)

The presented study aims to extend the knowledge of toxicological profile of rare earth elements salts(REEs).The basal toxicity test performed comprised assessment of cytotoxicity(3 T3 Balb/c Neutral Red Uptake Test)that allows for calculation of LD50(rats)on the basis of the concentration which leads to a50%reduction in cell growth(IC50).Environmental toxicity was addressed by the Tubifex tubifex(T.t.)express test.The in vitro skin irritation(OECD TG 439)and skin corrosion tests(OECD TG 431)utilizing the 3 D in vitro reconstructed human epidermal model EpiDerm(MatTek IVSL,SK)were used for assessment of skin irritation and corrosion potential hazard of REEs.Mutagenic effects were determined using the bacterial reverse mutation assay(Ames Test)on 5 Salmonella typhimurium strains with and without metabolic activation(OECD TG 471).Endocrine disruption was evaluated by means of a yeastbased assay YES/YAS(Xenometrix,CH).Skin sensitization was assessed using the LuSens assay,based on a genetically modified human keratinocyte cell line(OECD TG 442 D).The tested REEs have no potential of mutagenicity or skin sensitization,exhibit very weak endocrine disruption potential and only exceptional local irritation/corrosion effects for thulium(Ⅲ)chloride anhydrous,but have acute and chronic toxic effects on the aquatic environment.

SOLVENT EXTRACTION OF LANTHANIDES BY 2-ETHYLHEXYLPHOSPHONIC ACID MONO-2-ETHYLHEXYL ESTER

The chemistry of extraction of lanthanide and yttrium by 2-ethylhexylphosphonic acidmono-2-ethylhexyl ester in n-dodecane from nitric acid is described. By M W determination, NMR and the slope method, the extraction reaction is studied.Based upon elementery analyses, IR, NMR as well as MW determination, the compositions ofthe complexes formed with La（NO3）3 and Nd（NO3）3 are studied. Both the standard enthalprchanges（-△H°） and the relative free energy and entropy changes （-△Zr°）（△SPr°）of the ex-.traction reaction are also estimated. The regularity of the variations of Kea（concentrationequilibrium constant）, -△AZr° and △Sr°reveals the tetrad effect. The average separationfactor of the adjacent lanthanides is calculated to be as high as 3.04.

Sorption of certain lanthanides by kieselguhr loaded with Cyanex 572 from sulfate medium

Kieselguhr for chromatography was loaded with Cyanex 572 extractant and characterized using X-ray diffraction(XRF),scanning electron microscopy(SEM),Fourier transform infra-red(FT-IR),and thermal analysis.Sorption of some heavy lanthanides together with yttrium by the prepared kieselguhr/Cy-572 sorbent was investigated by batch experiment in terms of initial metal ions concentrations,volume to solid mass ratio(V/m),sulfuric acid concentration as well as temperature.The sorption equilibrium of Cy-572 loaded kieselguhr was satisfactorily explained by the pseudo second-order kinetic model and Langmuir isotherm data.Furthermore,the values of thermodynamic parameters △G°,△H°,and △S°at25℃of the studied metal ions show that the process is spontaneous and endothermic in nature.2.0 mol/L HNO3 is promising to desorb these metal ions.

Fast cleavage of 3', 5'-cycIic adenosine monophosphate and 3', 5'-cyclic guanosine monophosphate by lanthanides

Synthetic nucleases which rapidly cleave nucleic acids under mild conditions have many important potential applications ranging from the synthesis of custom-designed artificial restriction enzymes to the development of new antitumor drugs. Nonenzymatic hydrolysis of nucleic acids has been attracting increasing interest. However, the cleavage of nucleic acids by lanthanides has rarely been reported, and only Sumaoka et al. observed

Investigation of aggregation in solvent extraction of lanthanides by acidic extractants (organo-phosphorus and naphthenic acid)

Three acidic extractants (Ⅰ) di(2-ethylhexyl) phosphoric acid (HDEHP),(Ⅱ) 2-ethylhexyl phos-phonic acid mono-2-ethylhexyl ester (KEHPEHE) and (Ⅲ) naphthenic acid were employed in preparing the samples for the characterization of the coordination structure of lanthanlde-extractant complexes and the physicochemical nature of aggregates formed in the organic diluent of the solvent extraction systems.Photo correlation spectroscopy (PCS) re-suits on the aggregates formed by the partially saponified HDEHP in n -heptane showed that the hydrodynamic radius of the aggregates was comparable to the molecular dimensions of HDEHP.The addition of 2-octanol into the diluent,by which the mixed solvent was formed,increased the dimensions of the corresponding aggregates.Aggregates formed from the ianthamde ions and HDEHP in the organic phase of the extraction systems were found very unstable.In the case of naphthenic acid,PCS data showed the formation of w/o microemulsion from the saponified naphthenic acid in the

Lanthanides' enhancing absorption of insulin and reduction of blood glucose of rat by pulmonary administration

To explore the possibility of lanthanides as the enhancer of insulin absorption, the promoting effects of lanthanide ions on the absorption of intrapulmonary delivered insulin and reduction of blood glucose were investigated by means of two approaches, preadministration and coadministration of lanthanide ions with insulin. The results indicate that, compared with the results of those given insulin only, lanthanide ions can effectively enhance the level of insulin and the reduction of glucose level in blood. These effects are dependent on lanthanide species and their concentrations. The mechanism was discussed.

Mechanism of the trivalent lanthanides’persistent luminescence in wide bandgap materials

The trivalent lanthanides have been broadly utilized as emitting centers in persistent luminescence(PersL)materials due to their wide emitting spectral range,which thus attract considerable attention over decades.However,the origin of the trivalent lanthanides’PersL is still an open question,hindering the development of excellent PersL phosphors and their broad applications.Here,the PersL of 12 kinds of the trivalent lanthanides with the exception of La^(3+),Lu^(3+),and Pm^(3+) is reported,and a mechanism of the PersL of the trivalent lanthanides in wide bandgap hosts is proposed.According to the mechanism,the excitons in wide bandgap materials transfer their recombination energy to the trivalent lanthanides that bind the excitons,followed by the generation of PersL.During the PersL process,the trivalent lanthanides as isoelectronic traps bind excitons,and the binding ability is not only related to the inherent arrangement of the 4f electrons of the trivalent lanthanides,but also to the extrinsic ligand field including anion coordination and cation substitution.Our work is believed to be a guidance for designing high-performance PersL phosphors.

TETRAD EFFECT IN SOLVENT EXTRACTION OF LANTHANIDES BY 2-ETHYLHEXYL PHOSPHONIC ACID MONO 2-ETHYLHEXYL ESTER

The regularity of the step-by-step variations of the physico-chemical properties relating to the trivalent ions of the lanthanides has long been considered as monotonic gradual variations. By examining the relationship between the distribution coefficients and the atomic numbers of the lanthanides in the process of solvent extraction,

SYNTHESIS OF INDENYL DICHLORIDES OF LANTHANIDES AND THEIR CATALYTIC ACTIVITIES OF POLYMERIZATION FOR BUTADIENE

In two previous papers, we reported the syntheses of cyclopentadienyl dichlorides of lower lanthanides and their catalytic activities of polymerization for dienes. A new series of organolanthanides containing the indenyl group and having the formulae C9H7LnCl2·（C4H8O）x（Ln=Nd,Pr,Gd, and Sm; C9H7=indenyl; C4H8O=tetrahydrofuran; x=0,1,2,3） and C9H7LnCl2·HCl·（C4H8O）x （Ln=Nd, Pr, and Sm;x=0,1,2） have also been synthesized.