Distribution Coefficient Of Nd Research Articles

Mass transfer efficiency in rare earth extraction using a hollow fiber pertraction device

Extraction of neodymium by N,N-dibutylacetamide (DBAc) has been investigated using a single hollow porous fiber pertraction device. It consists of a polypropylene hydrophobic fibre maintained in a cylindrical glass calender. The Nd loaded aqueous phase flows inside the porous fiber. The organic phase flows outside in the calender and fills the pores of the membrane. Neodymium is extracted by DBAc, transported through the membrane by molecular diffusion and collected in the solvent flow. DBAc was chosen taking into account its efficiency with regard to the extraction of rare earths, estimated initially by liquid–liquid extraction, and because of its low variation of viscosity with metal concentration. Accurate measurements of diffusion coefficient of neodymium in the solvent by Taylor Dispersion Analysis (TDA) confirmed the low influence of the neodymium concentration on its diffusivity. These results, combined with the determination of the distribution coefficient of Nd in DBAc, gave good agreement between experimental and simulated data of pertraction test. Nevertheless, the results showed a high resistance of mass transfer mainly due to the diffusion in membrane. A possible explanation was that the distribution coefficient of Nd was not high enough to ensure a sufficient gradient of concentration along the thickness of the membrane filled by the solvent. To prove it, a second pertraction experiment was performed using HDEHP at 1 mol L−1 in n-dodecane as extractant. In this case, the distribution coefficient of Nd is 3 times higher than for DBAc. Good fitting of experimental data with simulated extraction of neodymium has been obtained and confirm the aforementioned hypothesis which assumes that high mass transfer rate requires high distribution and diffusion coefficients.

Efficient Recovery of Neodymium in Acidic System by Free-Standing Dual-Template Docking Oriented Ionic Imprinted Mesoporous Films.

Neodymium (Nd) is critical component of sintered neodymium magnets. Separation of Nd from consumer magnets has attracted a widespread attention. In this paper, we presented free-standing ionic imprinted mesoporous film materials for facile and highly efficient targeted separation of Nd from permanent magnets by dual-template docking oriented ionic imprinting (DTD-OII) method. DTD-OII is based on dual-template docking oriented molecular imprinting. Compared with conventional imprinting, this novel strategy does not need extra steps, but significantly advance imprinted efficiency. With optimization of functional monomer, our free-standing dual-template docking oriented ionic imprinted mesoporous films exhibit excellent adsorption of Nd by solid-liquid extraction. The Nd adsorption capacity for optimized films was 34.98 mg g-1 under pH = 3.0. The distribution coefficient of Nd was 636 mL g-1, which indicates films possess significantly selectivity of Nd. In addition, efficient dual-template docking oriented ionic imprinting makes films demonstrating an outstanding of reusability by cycle test, which appreciating their potential for industrial application.

염산용액에서 유기인산계 추출제에 의한 Nd와 Pr의 분리추출

Abstract Solvent extraction experiments have been performed to separate Nd and Pr from chloride leaching solution of monazite sandusing single Cyanex272 and mixed extractants as PC88A+Cyanex272 and PC88A+TBP. For this purpose, the effect of the con-centration of extractants on the extraction and separation of the two metals were studied by varying the pH of aqueous solution.In the experimental ranges conducted in this study, the distribution coefficients of Nd were higher than those of Pr. In Cyanex272system, our results indicated that concentration of extractant and initial pH did not affect distribution coefficients, but separationfactor was increased with increasing initial pH. In binary extractant system, distribution coefficients were lower than those ofsingle PC88A system, whereas separation factor was similar in both mixed and single extractant system.Key words : solvent extraction, Cyanex272, NdCl 3 , PrCl 3 , separation * Received : February 4, 2014 · Revised : March 5, 2014 · Accepted : March 18, 2014Corresponding Author : Man-Seung Lee (E-mail : mslee@mokpo.ac.kr)Department of Advanced Materials Science & Engineering, Mokpo National University, 61 Dorim-ri, Chungkye-myun, Muan-gun,Chonnam, 534-729, KoreaTel : +82-62-450-2492 / Fax : +82-62-450-2498 ⓒThe Korean Institute of Resources Recycling. All rights reserved. This is an open-access article distributed under the termsof the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permitsunrestricted non-commercial use, distribution and reproduction in any medium, provided the original work is properly cited.

모나자이트 샌드의 염산침출용액으로부터 용매추출에 의한 Nd와 Pr의 분리

Abstract Solvent extraction experiments have been performed to separate Nd and Pr from chloride leaching solution of monazite sandusing PC88A and D2EHPA. For this purpose, the effect of the saponification of PC88A and D2EHPA on the extraction and sep-aration of the two metals were studied by varying the pH of aqueous solution. In the experimental ranges conducted in this study,the distribution coefficients of Nd were higher than those of Pr and separation factor value increased with the increase of solutionpH. Saponification of PC88A enhanced the distribution coefficients of Nd and Pr as well as the separation factor. Saponificationof D2EHPA had some effect on the extraction of the two metals but little effect on the separation factor.Key words : Solvent extraction, PC88A, D2EHPA, Saponification, Separation *Received : August 19, 2013 · Revised : September 9, 2013 · Accepted : September 23, 2013Corresponding Author : Man-Seung Lee (E-mail : mslee@mokpo.ac.kr)Department of Advanced Materials Science & Engineering, Mokpo National University, 61 Dorim-ri, Chungkye-myun, Muan-gun,Chonnam, 534-729, KoreaTel : +82-62-450-2492 / Fax : +82-62-450-2498 ⓒThe Korean Institute of Resources Recycling. All rights reserved. This is an open-access article distributed under the termsof the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permitsunrestricted non-commercial use, distribution and reproduction in any medium, provided the original work is properly cited.

염산용액(鹽酸溶液)에서 PC88A와 D2EHPA에 의한 Nd와 Pr의 분리추출(分離抽出)

Solvent extraction experiments have been performed to investigate an optimum condition to separate Nd and Pr from chloride solutions using PC88A and D2EHPA. In our experimental ranges, the distribution coefficients of Nd were higher than those of Pr. In both of PC88A and D2EHPA extractant system, our results indicated that the increase in concentration ratio of extractant to metal had a great effect on the extraction and separation of the two metals. In extraction with saponified D2EHPA, the initial pH of the aqueous solution and saponification degree had some effect on the extraction of the two metals but little effect on the separation factor.

Growth and characterization of LiYF 4:Nd single crystal fibres for optical applications

The micro-pulling-down technique has been employed to grow long and regular in diameter Nd-doped LiYF 4 single crystal fibres. The effective distribution coefficient of Nd 3+ ion in the YLF crystal fibres was estimated. The optical absorption and emission of an YLF:Nd bulk crystal and YLF:Nd crystal fibre were compared. The absorption bands of the Nd 3+ ion, in the visible and in the near infrared, are similar for both materials. The fibre showed an emission band with maximum at 1047 nm and luminescence lifetime of the 4F 3/2 state of 390 μs while the bulk crystal exhibits the luminescence lifetime of 460 μs.

Growth of RE:LuVO4 (RE=Nd, Tm, Yb) single crystals by the floating zone method and their spectroscopic properties

Neodymium, thulium and ytterbium-doped lutetium orthovanadate (RE:LuVO4) single crystals were successfully grown by the floating zone method under the atmosphere of a pure oxygen flow. All the grown crystals had no cracks and no inclusions for any dopant and concentration. Post-growth annealing at 1000°C in air was effective in eliminating the coloring in yellowish ocher. Effective distribution coefficient of Nd in LuVO4 was found to be about 0.5 whereas those of Tm and Yb are nearly unity. Polarizing microscopy demonstrated that most crystals had no growth striations except for the Nd-doped crystals. The absorption coefficients of Nd:LuVO4 and Tm:LuVO4 around 800nm were much higher than those of Nd:GdVO4 and Tm:GdVO4. For the Tm:LuVO4, relative intensity of fluorescence spectrum was higher than that of Tm:GdVO4 above 1900nm where the self-absorption could be neglected. The width of fluorescence spectrum of Yb:LuVO4 around 1μm was comparable to that of Yb:YVO4, indicating the possibility of formation of quasi-three level for lasing at room temperature.

Solvent extraction of neodymium ions from hydrochloric acid solution using PC88A and saponified PC88A

Solvent extraction experiments of Nd with PC88A and 40% saponified PC88A from chloride solution have been performed. Compared to the distribution coefficients of Nd with PC88A, the use of 40% saponified PC88A significantly increased the extraction of Nd. The extraction reaction of Nd with PC88A was identified using a graphical method. The equilibrium constants for the solvent extraction of Nd with PC88A and saponified PC88A were estimated from the experimental data. The measured distribution coefficients of Nd with PC88A and saponified PC88A agreed well with those calculated in this study from the initial extraction conditions.

Separation performance for trivalent actinides from lanthanides by thiacalix[4]arenes compounds impregnated silica ion-exchanger

Silica ion-exchangers impregnated new thiacalix[4]arenes compounds were prepared and investigated the adsorbed performance for Am and lanthanides. The maximum distribution coefficient of Am over the exchanger was 5000 cm 3/g in weak-acid solution. In contrast, the distribution coefficient of Nd or Eu was below 10 cm 3/g. It was shown that thiacalix[4]arenes compounds have the selective adsorption for Am. The influence of the gamma ray irradiation to the selective adsorption was also investigated.

Peculiarities of synthesis and flux growth of neodymium yttrium aluminum borate crystals

The conditions for solid-state synthesis of neodymium yttrium aluminum borate (NYAB) charges have been defined, and crystals with different neodymium concentrations have been grown by spontaneous crystallization from K 2Mo 3O 10—B 2O 3 fluxes. Decomposition temperatures and lattice parameters of NYAB crystals and synthesized charges have been measured by differential thermal analysis and X-ray diffraction methods. Both (a,c) lattice constants increased with the increasing amount of Nd content, while decomposition temperatures decreased. The distribution coefficient of Nd in NYAB crystals is in the range of 0.6–0.8.

Crystal growth and optical properties of Bi 4Si 3O 12 : Nd

The Bridgman growth of Nd doped Bi 4Si 3O 12 (BSO) single crystals are reported for the first time. Good quality crystals were grown with Nd concentration level as high as 5.0 at%. It has been found that the absorption coefficients at the peak wavelengths of 743 and 809 nm were 34 and 19 cm −1, respectively, for 5.0 at% Nd doping. The distribution coefficient of Nd in BSO was also determined by means of chemical analysis and it was found to be 1.1. Fluorescence lifetime measurement was also carried out and the intrinsic lifetime of fluorescence intensity, τ 0 was calculated to be 268 μs.

Growth and characterisation of monoclinic KGd 1− xRE x(WO 4) 2 single crystals

The high-temperature solution growth of KGd(WO 4) 2 single crystals doped with trivalent rare earth (RE 3+) ions has been investigated by using the top seeded solution growth (TSSG) technique and K 2W 2O 7 as solvent. Electron probe microanalyses were used to determine the RE concentration in the crystals grown. For the 1% doping level in the melt the distribution coefficients of Nd, Er, Ho and Tm are in the 0.8–1.1 range. Yb and Pr have smaller distribution coefficients of 0.7 and 0.5, respectively. The crystal field splittings of the Ho 3+, Er 3+ and Yb 3+ electronic multiplets have been determined at 4.2 K. Some evidence of the presence of several Yb 3+ centres has been obtained.

Neodymium concentration measurements in Nd:YLF laser rods: a nondestructive method

A nondestructive method for measurements of Nd(3+) concentration in Nd:YLF laser rodes is presented. The method, based on the comparison of the intensities of Nd(3+) luminescence lines to the intensities of the host matrix (LiYF(4)) Raman lines, requires the use of a micro-Raman spectrometer. The experimental conditions have been optimized and are described in detail. The investigations were performed in the concentration range 0at.%-2at.% of Nd and the calibration curve is presented. In standard use, the relative error on the results never exceeds 10%. Using this method to study the concentration gradient in a crystal is shown and the distribution coefficient of Nd(3+) in LiYF(4) is deduced.

Crystal growth and perfection of large Nd:YAG single crystals

Single crystals of Nd:YAG are [111] grown in production quantities to a size of 4 cm diameter and 20 cm long. The principal boule defects are a 2 mm diameter {211} faceted core, strain lines along 〈110〉, and impurity striae characteristic of the growth interface. The initial distribution coefficient of Nd was found to be 0.15. The Nd concentration along the boule length increases about 20–30% in 20 cm. Lang X-ray topographs of slices cut along [111] clearly reveal the defective core and the striae distribution. Excessive strain in the boules is visible under crossed polarizers and in Twyman-Green interferograms. The cause of strain is probably a growth rate larger than the equilibrium rate required to incorporate a fixed amount of Nd. Efforts to increase the amount of Nd in the crystal by Lu additions have been fruitful but the same defects remain in Nd, Lu:YAG when examined by X-ray topography.

Calcium tungstate—III: Trivalent rare earth substitution

The charge compensation of trivalent rare earths in the divalent Ca site of calcium tungstate was studied by the determination of distribution coefficients. The behavior of neodymium was investigated in the presence of all the alkali metal ions and niobium, and all the other rare earths in the presence of sodium.The distribution coefficient of Nd is found to vary with the concentration of Nd itself, as well as with the concentration of charge compensating ions present. Several separate mechanisms including vacancy formation are inferred, and are confirmed by paramagnetic resonance results.In the next paper a theory covering this data is presented. Columnar growth has been observed and can be caused by either CaO or WO3 excess in the melt.