Removing Al from Rare Earth Chloride Solution by Method of Extraction

Using long-chain fatty acid as extractant, the process of removing the impurity element aluminum in the solution of praseodymium-neodymium chloride and the influence of extracting conditions were studied. The results show that the amount of aluminum can be decreased from 728 to 14 mg·L -1 that is the 98% of total in the solution of praseodymium-neodymium chloride by one-stage extraction under the condition as follows: the concentration of rare earth is 100～200 g·L -1, the organic phase is 20% fatty acid -10% isooctanol -70% kerosene (V/V), saponification number is 20% with dense ammonia, and the extracting equilibrium time is 5～15 min. Under the same conditions, the extraction ratio of aluminum in the system of fatty acid is 3～5 times of that in naphthene acid. The fatty acid extractant is distinctly better than naphthene acid.

Progress of Separation and Determination Methods for Rare Earth Elements

This review covers the developments in rare earth elements analysis over the period from 2003 to 2005. Some novel separation and determination methods and their applications in rare earth elements analysis were presented and discussed in detail. Some new materials, such as ionic liquids, nanometer materials and ion-imprinted polymers, and some new technologies, such as cloud point extraction, membrane extraction and capillary electrophoresis were successful used in rare earth elements analysis. The determination methods of NAA, ICP-OES and ICP-MS were also discussed in detail.

Study on the Spectrophotometric Determination of Rare Earths with a New Chromogenic Reagent Dibromo-p-methyl-chlorosulfonazo(DBMCSA)

A new method for the determination of cerium subgroup rare earths was studied and reported ill this paper. It was found that cerium subgroup rare earth elements react with DBMCSA in 0.6 mol/L hydrochloric acid medium to form stable blue complexes. The absorbances of equal amounts of cerium subgroup rare earths are close to each other at their maximum adsorptive wavelength (641 nm). Beer's law is obeyed for 0-20 mu g of I ars earths in 25 mi of solution. The method has been applied to the determination of the total amount of cerium subgroup rare earths in steel and cast iron samples with satisfactory results.

Determination of Light Rare Earths by a Spectrophoto-metry Based on the Linear Combination of Multiwavelength Data

The present paper proposes a new method of spectrophotometry based on linear combination of multiwavelength data by means of selecting a set of properly weighted coefficients and combination methods. It is clear that the weighted combination absorbance attained is only in direct proportion to the concentration of the analysed component and independent of coexisting interferents.The accuracy of the analytical results is improved greatly for the analysis of light rare earths with the coexistence of heavy rare earths.The analyti- cal error from the reagent blank and co-coloration of light and heavy rare earths have also been overcome. The greatly improved linearity and additivity of absorbance are obtained.

THE ROLE OF RARE EARTH CHLORIDES IN THE PACK-TiC COATING AGENT

If 1% rare earth chloride is added to the coating agent containing 5% AlCl_3,the coating efficiency of TiC will be increased greatly.A protective crust consisting of Al_2(SiO_3)_3 and SiO_2 will form on top of the coating agent in the temperature range of 850～1000℃ when SiO_2 powder of a thickness of 5～10 mm is spread on top of it.The protective crust can offer a good air-proof property and increase the denseness of the coating structure.

ELECTRONIC STRUCTURE AND BOND CHARACTER OF COMPLEXES OF RARE EARTH CHLORIDES WITH CROWN ETHERS

A series of lanthanide complexes LnCl_3·L(Ln=La,Pr,Nd;L=15-C-5 or 18-C-6)have been synthesized and their molecular configuration,electronic structure and bond character have been studied by XPS and quantum chemical calculation.The calculated results are in good agreement with that obtained in the experiments.Three Cl atoms are on the same side of Ln in LnCl_3·15-C-5 and the crown ring on the other side.forming a complex molecule with coordination number 8.LnCl_3·15-C-5 is easily hygroscopic in air because of its unsaturated coordination,which differs sharply from the stable Ln(NO_3)_3·15-C-5 com- plex of coordination number 11.The HOMO and neighboring occupied MOs are composed of Cl 3p and O2p, and the LUMO and neighboring unoccupied MOs are composed of Ln orbitals.The level structure easily pro- duces Ln3d satellite in XPS caused by L→Ln charge transfer transition.Due to the coordination,the absolute values of the charge are decreased at Ln and O atoms,but increased at Cl atoms,which is in agreement with XPS results.

THE USE OF CHELATING RESIN FOR THE PRE-CONCENTRATION OF TRACE RARE EARTH ELEMENTS IN BIOLOGICAL SAMPLES AND THEIR DETERMINATION

Macroporous amino-carboxvlic chelating resin of acrylic acid series may concentrate trace rare earth in the presence of 0.1 mol/l α-hydroxy-isobutyric acid at pH 4.5.With 0.10 mol/l HCl as eluant rare earth may be eluted quantitatively and separated from Ca,Mg,Fe and Cu.This method is used to determine trace amount of rare earth in human hair,stone (in kidney and bladder),peanut,grape,strawberry,cucumber,pig liver and other biological samples.

DIRECT DETERMINATION OF NEODYMIUM AND ERBIUM IN RARE EARTH MIXTURE BY DERIVATIVE SPECTROPHOTOMETRY

The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid in the presence of diethylamine and ethanol have been measured by normal and third-derivative spectrophotometry. Their molar absorptivities are 70.7 l.mol^(-1).cm^(-1) for Nd and 62.5 l.mol^(-1).cm^(-1) for Er. They are 7.6 times and 14.9 times greater than those of corresponding chlorides, respectively. Use of the third-derivative spectra both eliminates the interference of Ce(Ⅳ) and increases the sensitivity for Nd and Er. Beer,s Law was obeyed from 0-10 ug/ml of Nd and Er. The method has been applied to the determination of neodymium and erbium in rare earth mixtures.

Rare Earth Stearates as Thermal Stabilizers for Rigid Poly(vinyl chloride)

A series of stearates with different rare-earth ion were investigated as thermal stabilizers for rigid PVC at 180 ℃ in air. Their stabilizing efficiency was based on measuring the rate of dehydrochlorination. The resulted revealed the higher stabilizing efficiency of the investigated rare-earth stearates as thermal stabilizers for rigid PVC compared with the thermal stabilizers for industry: calcium stearate, zinc stearate, butyl stannum mercaptide, phosphite esters, β-diketone and epoxidized sunflower oil. This was well illustrated by longer incubation period (T_S) values and lower rate of dehydrochlorination. The stable efficiency was affected by the nature of rare-earth element's individual electronic shell. The mechanism for the stabilizing effect of rare-earth stearates was proposed. The result was experimentally proved based on IR spectrum.

Determination of Trace Impurities of Rare Earth Elements in High Purity Yttrium Oxide by ICPMS

Determination of trace rare earth elements(REEs)in 99. 999% purity yttrium oxide using the inductively coupled plasma mass spectrometric technique (ICPMS) has been developed. Instrumental parameters and factors affecitng analytical results have been studied and then optimized.Samples are analyzed directly following an acid digestion without separation or preconcentration and with limit of detection of 0. 003～0. 02 ng/ml, precision of ±5. 4%(cofficient of variation)and recovery of 90～115%. Correction for isobaric interferences from oxide ions and hydroxide ions is made mathematically. Special internal standard procedures are used to compensate drift in metal:metal oxide ratios and sensitivity. The analytical results of several samples are accurate as compared with inductively coupled plasma atomic emission spectrometry (ICPAES) and spark source mass spectrometry (SSMS).

Electrodeposition of Rare Earth Metals and Their Alloys

The cyclic voltammetry, potentiostatic electrolysis and open circuit potential-time curve after electrolysis, current-time curve at potential step, X-ray diffraction, EDAX and electron probe microanalysis were used to investigate the electrodeposition of rare earth metals and their alloys in molten chlorides. The electrode processes and the mechanism of forming alloy were studied. The free energies of formation for the intermetallic compounds, the diffusion coefficients and diffusion activation energies of RE(III) ions in melt, the diffusion coefficients and diffusion activation energies of RE atoms in alloy phase were determined. The rare earth-iron group alloys were prepared by consumable cathode and electrolytic codeposition.

Extraction and separation of yttrium from other rare earths in chloride medium by phosphorylcarboxylic acids

Two phosphorylcarboxylic acids,3-((bis(2-ethylhexyloxy))phosphoryl)propanoic acid(PPA) and 3-((bis(2-ethylhexyloxy))phosphoryl)-3-phenylpropanoic acid(PPPA),were synthesized for separating yttrium from other rare earths in the chloride feed of ion-adsorption type rare earth concentrate.The effect of the factors such as pH_(1/2),temperature,saponification degree and phase modifiers was investigated.The separation efficiencies of PPA and PPPA are obviously better than the typical extractants such as sec-octylphenoxy acetic acid(CA-12) and naphthenic acid(NA).The extraction process of rare earths by PPA and PPPA is a cation exchanging reaction,which is similar to those of CA-12 and NA.The loaded rare earths in both PPA and PPPA systems can be effectively back-extracted by 0.5 mol/L HCl or higher concentration.A cascade extraction process for separating yttrium from other rare earths was developed using PPPA as the extractant.The yttrium product with the purity of 97.20 wt% was obtained by 35 stages of extraction and 12 stages of scrubbing.

Decomposition Reaction of Mixed Rare Earth Concentrate and Roasted with CaO and NaCl

The reaction of the mixed rare earth concentrate including monazite ( REPO4 ) and bastnaesite ( REFCO3 )decomposed by CaO and NaCl additives at the temperature range from 100 to 1000 ℃ was studied by means of XRD and TG-DTA.The results show that when CaO and NaCl are not added, only REFCO3 can be decomposed at the temperature of 377 ～ 450 ℃.The decomposition products include REOF, RE2O3 and CeO2.However, REFCO3 can not be decomposed.When CaO is added, the decomposition reactions occur at the temperature range from 660 to 750 ℃.CaO has three decomposition functions: ( 1 ) REPO4 can be decomposed by CaO and the decomposition products include RE2O3 and Ca3 (PO4)2; (2) CaO can decompose REOF, and the decomposition products are RE2O3 and CaF2; (3)CaO can decompose REPO4 with CaF2, and the decomposition products are RE2 O3, Ca5 F( PO4 )3.The decomposition ratio of the mixed rare earth concentrate increased obviously, when CaO and NaC1 were added.NaC1 can supply the liquid for the reaction, improve the mass transfer process and accelerate the reaction.At the same time, NaC1 participated in the reaction that REPO4 was decomposed by CaO.

Ce_(1–x)La_xO_y solid solution prepared from mixed rare earth chloride for soot oxidation

Ce_（1–x）La_xO_y solid solution was simply prepared using mixed rare earth chloride（RECl_3·x H_2O, RE=Ce, La99%, containing unseparated Ce and La from rare earth metallurgical industry） as precursor by ultrasonic-assisted co-precipitation method with different ultrasonic frequencies（CLf, f=200, 400, 600, 800, 1000 Hz）. A compared Ce_（1–x）La_xO_y solid solution（CL＊） was also prepared by the same mothod with 10% less precipitant. X-ray diffraction results confirmed the formation of Ce1–xLaxOy solid solution, and the crystal structures of these catalysts were not very sensitive to ultrasonic frequency and precipitant amount. However, both of the factors had obvious effect on morphology and surface area of CL, and precipitant amount seem to play a more crucial role than ultrasonic frequency for Ce_（1–x）La_xO_y solid solution preparation. When soot and catalyst were tight contacted, the peak temperature（Tpeak） of soot oxidation and oxygen reducing temperature for CLf catalysts decreased linearly with increasing surface area. Under loose contact condition, the Tpeak had obvious negative correlation with H_2 consumption. It was inferred that good reducibility of the Ce_（1–x）La_xO_y solid solution favored the soot oxidation reaction. The Ce_（1–x）La_xO_y solid solution prepared from unseparated rare earth chloride showed a good soot oxidaiton activity. Controlling the preparation conditions to prepare a CL catalyst would high surface area will enhance its reducibility and activity.

Studies on Solvent System of Cesium Chloride and Lanthanum Chloride and Synthesization of Four Types of New Compounds

This article describes the solubility data of the quaternary systems of CsCl LaCl 3 HCl H 2O(25 ℃, HCl 13% or 23%(wt)) and CsCl LaCl 3 HAc H 2O(30 ℃, HAc 42%(wt)), and the corresponding solubility equilibrium diagrams. Three new compounds, CsCl·LaCl 3·4H 2O, 2CsCl·LaCl 3·2H 2O and 3CsCl·LaCl 3·3H 2O have been found. From analysis of the systems by the X ray powder diffraction, TG DTG and DTA, the properties of the compounds are presented. The interpretation of the mechanism of Meyer′s reactions is discussed further and the synthesis method of four type new compounds is offered.

Thermochemistry on Coordination Behavior of Neodymium Chloride Hydrate with Diethylammonium Diethyldithiocarbamate

The complex of neodymium chloride lower hydrate with diethylammonium diethyldithiocarbamate (D-DDC) was synthesized conveniently in absolute alcohol and dry N_2 atmosphere. The title complex was identified as Et_2NH_2[Nd(S_2CNEt_2)_4] by chemical and elemental analyses and the bonding characteristics of which was characterized by IR. The enthalpies of solution of neodymium chloride hydrate and D-DDC in absolute alcohol at 298.15 K and the enthalpies change of liquid-phase reaction of formation for Et_2NH_2[Nd (S_2CNEt_2)_4] at different temperatures were determined by microcalorimetry. On the basis of experimental and calculated results, three thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), the rate constant and three kinetic parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of liquid-phase reaction of formation were obtained. The enthalpy change of the solid-phase title reaction at 298.15 K was calculated by a thermochemical cycle.

Friction and wear performances of borates and lanthanum chloride in water

The antiwear and friction-reducing performances of sodium borate, potassium borate and lanthanum chloride in water were evaluated on a four-ball friction tester. The topographies, element distribution and chemical characteristics of the worn surfaces were investigated by scanning electron microscope （SEM）, energy dispersion of X-ray （EDX） and X-ray photoelectron spectroscope （XPS）. The results indicated that sodium borate, potassium borate and lanthanum chloride increased extreme pressure, antiwear and friction-reducing capacities of water to a certain extent, of which potassium borate was the best candidate. Combination of lanthanum chloride with sodium borate and po- tassium borate respectively further improved antiwear and friction-reducing capacities. Scratches of worn surfaces lubricated with water containing borates and lanthanum chloride were less severe than those lubricated with water containing borates alone. A tribochemical film mainly composed of oxides of lanthanum, boron and iron reduced friction and wear for water lubricant formulated with both borates and lanthanum chloride.

Biochemical effects of gadolinium chloride in rats liver and kidney studied by ^1H NMR metabolomics

The biochemical effects of gadolinium chloride were studied using high-resolution IH nuclear magnetic resonance （NMR） spec- troscopy to investigate the biochemical composition of tissue （liver and kidney） aqueous extracts obtained from control and gadolinium chloride （GdCl3） （10 and 50 mg/kg body weight, intraperitoneal injection, i.p.） treated rats. Tissue samples were collected at 48, 96 and 168 h p.d. after exposure to GdCI3, and extracted using methanol/chloroform solvent system. ^1H NMR spectra of tissue extracts were analyzed by pat- tern recognition using principal components analysis. The liver damages caused by GdCl3 were characterized by increased succinate and decreased glycogen level and elevated lactate, alanine and betaine concentration in liver. Furthermore, the increase of creatine and lactate, and decrease of glutamate, alanine, phosphocholine, glycophosphocholine （GPC）, betaine, myo-inositol and trimethylamine N-oxide （TMAO） levels in kidney illustrated kidney disturbance induced by GdCl3.

Determination of Formation Constants of Ce^(3+) Complexes by Fluorescence

Fluorescence of Ce 3+ (aq) is very strong and thoroughly quenched when Ce 3+ forms complexes with ligands containing carboxylate or phosphate groups. This property is employed to develop a new simple method to determine formation constants of Ce 3+ complex system. Fluorescence intensity is used to determine concentration of Ce 3+ (aq) in complex solution, as it is proportional to the concentration of Ce 3+ (aq). In this paper, two examples, Ce 3+ malonic acid and Ce 3+ AMP(adenosine 5′ monophosphate), of fluorescence titration were made and association constants and association numbers of the two systems were deduced for the titration with Scatchard plot. The results are similar to those obtained by others. It is suggested that this Ce 3+ method is a promising fluorescence probe, as it is not only simple but also superior to other lanthanide fluorescence probe in being able to study a large amount of organic ligands and biomolecules.