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.

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 sails added on the distribution of lanthanides between two phases were investigated. Two different compositions Ln(H2O)(t-2) (TOPO)(2)(OH)(2)NO3 (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 K-ex and pH(1/2) value were calculated and the thermodynamic parameters were obtained from the dependence of K-ex on the temperature.

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

The preliminary studies of the effects of lanthanides(Lns) on hemoglobin are reported. It has been revealed that Ln ions reduce the oxygen saturation of hemoglobin and the oxygen releasing potency of oxyhemoglobin under reduced partial pressure of oxygen. The Ln ions do not replace the iron atom in the heme probably due to the conformational change of hemoglobin induced by Ln binding, which was investigated by circular dichroism(CD) and fluorescence spectra.

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 LnA_3(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.

Characteristics of Trivalent Lanthanides in Coordination Chemistry

Some basic characteristics of lanthanide-oxygen bonds in various trivalent lanthanide metal-organic complexes are quantitatively studied by the bond valence model. Some important relationships among the electronegativity, bond valence parameter, bond length and lanthanide coordination number in these complexes are generally found , which show that for each trivalent lanthanide cation all calculated parameters may well be correlated with its coordination number in their coordination complexes. Specifically,32 new data for the bond valence parameter are first calculated in this work.An approximate linear relationship between the Ln-O bond valence parameter and the coordination number of Ln^(3+) is obtained.The Ln-O bond length increases with the increase in the lanthanide coordination number.The difference of electronegative values decreases with the increase in the lanthanide coordination number.

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 in...

Solution and Thermodynamic Studies on Binary and Ternary Complexes of Lanthanides

The interactions of La（ Ⅲ ）, Pr（ Ⅲ ）, Nd（ Ⅲ ）, Sm（ Ⅲ ）, Eu（Ⅲ）, Gd（ Ⅲ ）, Dy（ Ⅲ ）, and Yb（ Ⅲ ） with cytosine, 5-bromocytosine, 5-azacytosine and 5-flurocytosine as primary ligands （L） and guanine （A） as secondary ligand for both binary （ 1 ： 1 ） as well as ternary （ 1 ： 1 ： 1 ） systems were investigated by potentiometric equilibrium measurements at 25, 35 and 45 ℃ in aqueous solution （ionic strength, μ = 0.1 mol·dm^-3 NaNO3）. The stability constants of the binary （ 1 ： 1 ） and ternary （ 1 ： 1 ： 1 ） metal-ligand complexes follow the following order La 〈 Pr 〈 Nd 〈 Sm 〈 Eu 〉 Gd 〈 Dy 〉 Yb. Results also indicate that the ternary lanthanide complexes of La（Ⅲ）, Pr（Ⅲ）, Nd（Ⅲ）, Sm（Ⅲ）, Eu（Ⅲ）, Gd（Ⅲ）, Dy（Ⅲ）, and Yb（ Ⅲ ） are more stable than corresponding binary lanthanide complexes. The enthalpy （△Hf^o） and entropy （△Sf^o） changes for the formation of binary and ternary complexes were calculated from temperature coefficient data. The △△Sf^o values are positive for all the metal ligand systems. The negative △△Hf^o values indicate the extra stability of the ternary complexes by the exothermic enthalpy changes （△△Sf^o = △TSf^o - △BSf^o and △△Hf^o = △THf^o - △BHf^o where △TSf^o, △THf^o and △BSf^o, △BHf^o are the entropy and enthalpy values associated with the ternary and binary complexes, respectively）. It was also proposed that the guanine is bonded to metal ions through N1/C6 = O and N7 whereas cytosine and its derivatives are bonded through N3 atoms in ternary complexes.

Polymerization of Acrylonitrile with(Diisopropylamido) Bis(indenyl) Lanthanides

The polymerization of acrylonitrile was studied using (diisopropylamido)bis(indenyl) lanthanides, Ind 2LnN(i Pr) 2(Ln=Y, Yb) as a single component catalyst. The effects of the amount of catalyst, monomer concentration and polymerization temperature on catalytic activity and molecular weight of polyacrylonitrile(PAN) were studied. The results show that the catalytic activity is raised obviously with rising polymerization temperature. The monomer conversion reaches 64% under polymerization temperature, monomer concentration and catalyst concentration are 50 ℃, 5.1 mol·L -1 and 0.3%(molar ratio) sequentially. The conversion and molecular weight of the polymer increase appreciably with adding additive, PhONa. When the molar ratio of PhONa to the catalyst is three, the conversion and the molecular weight is 76% and 1.32×10 4, respectively. The initiation mechanism for the polymerization of acrylonitrile was proposed.

SOLVENT EXTRACTION OF LANTHANIDES IN AQUEOUS NITRITE MEDIA BY CYANEX 302

Solvent extraction of trivalent lanthanides (except for Pm with Cyanex 302 [Bis (2,4,4-trimethylpentyl)monothiophosphinic acid] in heptane was studied at various aqueous pH values, extractant concentrations and different temperatures. Cyanex 302 shows pretty good behaviours on the extraction of lanthanides, especially when extracting heavy lanthanides. However,purified Cyanex 302 exhibits signi ficantly lower extractability to lanthanides than raw extractant. The roles ofdifferent components ofraw Cyanex 302 were discussed to understand the reason of good extractability of the raw extractant. The lanthanides extraction stoichiometry is discussed on the basis ofexperimental results, which can be expressed as follows:

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.

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/...

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.

The Geochemical Effect of Lanthanides: Its Types and Application for Magmatic Rocks—A New Method to Semi-Quantitatively Determine Strength of Magmatic Fluid Complexation and Fractional Crystallization

In this paper, the relationship between rare earth elements （REEs） geochemical behavior and their ionic radii was studied. According to the basic law called the effect on geochemistry of lantha- nides, five types and some of subtypes of REEs occurrence, both in magmatic rocks and their minerals, were found, which may correspond to the evolutionary way of magmatic rocks. Analysis of REEs data for an amazonite-topaz granite pluton in East Xinjiang, one of the administrative regions of West China, and Cenozoic alkaline volcanic-intrusive rocks in the Xialiaohe depression of Bohai Bay Basin, China show that types II1, III and IV of effect on geochemistry of lanthanides not only reflect fluid complexa- tion and fractional crystallization existed in magmatic evolution directly, but also can determine semi-quantitatively the strength of fluid complexation and fractional crystallization. Therefore, the ef- fect on geochemistry of lanthanides, a new way to study semi-quantitatively evolution of magmatic rocks, is probably practicable. Moreover, the mafic lavas of different sources from the margin of Gonghe Basin, Qinghai Province, China, can be effectively distinguished in the diagram which can be drawn with some parameters of linear equation of LREEs and its ion radius.

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.

Solution extraction of several lanthanides from nitric acid with isohexyl-BTP in [C_nmim][NTf_2] ionic liquid

The extraction behavior of several lanthanides（La^3＋, Eu^3＋, Lu^3＋） from nitric acid（HNO3） solution was studied using a novel extraction system based on 2,6-bis（5,6-dihexyl-1,2,4-triazin-3-yl） pyridine（isohexyl-BTP） as extractant in 1-alkyl-3-methylimidazolium bis（trifluoromethylsufonyl）imide（[Cnmim][NTf2]） ionic liquid. Isohexyl-BTP in ionic liquids exhibited remarkably better extraction performance for lanthanides than that in octanol-dodecane（3：7 v/v） system. Lower HNO3 concentration and short alkyl chain length of [Cnmim]^＋ were more favourable for removal of lanthanides. Besides, it was confirmed that isohexyl-BTP in ILs formed a 1：3 complex [Ln（BTP）3（NO3）n]^（3–n）＋（n=0, 1） by slope analysis. In addition, [C2mim][NTf2] preferred to extract lanthanides via a cation exchange mechanism at lower acidity, which was proved via UV-Vis measurement. It was speculated that extraction mechanism shifted from cation exchange to neutral species extraction with increase in HNO3 concentration and alkyl chain length of [Cnmim]^＋ due to the H^＋ completion, NO3^- inhibition and hydrophobicity of IL.

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 mixed solvent The extraction of lanthamdes by the saponified naphthenic acid in the mixed solvent under the given experimental conditions was a process of destruction of the w/o microemulsion.A possible mechanism of the breakdown of the w/o microemulsion droplets is discussed.