Simultaneous Extraction of Neodymium and Uranium using Hollow Fiber Supported Liquid Membrane

Simultaneous extraction of neodymium and uranium ions from aqueous nitrate media was investigated using hollow fiber supported liquid membrane (HFSLM). The organic phase supported in the membrane pores consisted of extractant N,N,N’,N’-tetraoctyl diglycolamide (TODGA), phase modifier isodecanol, and diluent n-dodecane. Experimental results suggest that there is competition between neodymium and uranium ions for complexation with TODGA. The initial rate of extraction of Nd³⁺ ions was found to be approximately six times to that of UO₂²⁺ ions. Experimental data was explained by a mathematical model for simultaneous transport of two metal ions. The model results were found to be in good agreement with the experimental data when the diffusivities of neodymium-TODGA complex (D_nm) and uranium-TODGA complex (D_um) in the membrane pore are 1.1 x 10^?11 and 4 x 10^?12 m²/s, respectively.     

High-efficiency HFSLM for silver-ion pertraction from pharmaceutical wastewater and mass-transport models

Hollow fiber supported liquid membrane (HFSLM) is a favorable technique for the pertraction of metal ions, especially at very low metal concentration. In this work, the pertraction of silver ions from acidic pharmaceutical wastewater via HFSLM was investigated. Pharmaceutical wastewater containing 30 mg/dm³ of silver ions and 120 mg/dm³ of ferric ions was subjected to HFSLM as a feed solution. LIX 84-I dissolved in organic solvent together with Na₂S₂O₃·5H₂O solution was selected for use as a liquid membrane and a receiving solution, respectively. The influence of ferric ions on the pertraction of silver ions was studied firstly using wastewater with normal ferric ion concentration and secondly using wastewater with ferric ion precipitation by phosphoric acid solution. The highest pertraction of silver ions was achieved by using 0.1 M of LIX 84-I and 0.5 M of Na₂S₂O₃·5H₂O solution at pH of feed and receiving solutions of 3.5 and 2. The flow rates of feed and receiving solutions were 0.2 dm³/min. 0.6 mg/dm³ of silver ions that remained in the wastewater was below the mandatory discharge limit. No effect of normal ferric ion concentration in the wastewater on silver ion pertraction was observed. The crucial parameters were defined to confirm the efficiency and reliability of the system. Finally, the controlling transport regime of silver ion pertraction across HFSLM was determined by the diffusion flux and reaction flux models.     

Separation of Co(II) and Mn(II) from sulphate media via a HFSLM: Reaction flux model and experimental verification

Separation of Co(II) and Mn(II) from sulphate media through triple HFSLM in series using D2EHPA was explored. Mn(II) was extracted preferentially over Co(II) at the pH value of 5, 100 ppm of Co(II) and Mn(II), 5% (v/v) of D2EHPA, 0.2 M HCl. The highest extraction percentage of Mn(II) was 98.14%, and Co(II) remained at 94.05% in the raffinate stream. The reaction order (n) and the reaction rate constant (k_f) were found to be 1.00 and 0.0180 min⁻¹, respectively. Furthermore, the reaction flux model proved to be in good agreement with the experimental data at an average deviation of 2.24%.     

Uranium Solvent Extraction and Separation From Vanadium in Alkaline Solutions

Quaternary amine could be used to extract uranium from alkaline leach solutions, but third phase formation prevented its application. In this paper, isodecanol was used as the modifier for Aliquat 336 in Shellsol D70 to extract uranium from a carbonate leach solution. The formation of third phase was eliminated. More than 98% of uranium was extracted using 3% (w/v) Aliquat 336 and 3% (w/v) isodecanol in Shellsol D70 from a carbonate leach solution containing 95 mg/L U and 25 mg/L V at pH 10.3 and room temperature in a single contact. The separation factor of uranium over vanadium increased with increasing pH of the auqueous solution and reached 280 at pH 11, indicating a good separation of the two metals. The co-extracted vanadium was scrubbed from the loaded organic solution at pH 11 using a solution containing 50 g/L Na₂CO₃. Over 90% of uranium was stripped from the loaded organic soluiton using an acidic solution containing 150 g/L ammonium sulphate in a single contact. It was also found that to obtain high uranium extraction, the chloride concentration should be controlled to less than 1 g/L in the aqueous phase.     

Mathematical model and experimental validation of the synergistic effect of selective enantioseparation of (S)-amlodipine from pharmaceutical wastewater using a HFSLM

A case study on the synergistic enantioseparation of (S)-amlodipine from pharmaceutical wastewater by using hollow fiber supported liquid membrane (HFSLM) was examined. A chiral reaction flux mathematical model was applied. Optimum conditions achieved the highest percentages of extraction and stripping viz. 84% and 80%, respectively. Relevant parameters affecting the enantioseparation efficiency of (S)-amlodipine were determined. Standard deviation percentages were 2.31% for extraction and 1.26% for stripping. It was found that the mathematical model proved to be in good agreement with the experimental data.     

改进的直接萃取法制备异辛酸钕

用氢氧化钠溶液代替氨水直接萃取法制备异辛酸钕.该法同氨水法相比,有容易监测,容易操作,反应快速和无刺激性气味等优点.该法制备的异辛酸钕对丁二烯聚合仍保持良好的催化活性.     

Thermal, Dielectric, and Optical Properties of Neodymium Borosilicate Glasses for Thick Films

Because of their thermal, dielectric, and optical properties, new glass compositions and thick-filmed transparent dielectrics containing neodymium oxide (Nd₂O₃) were studied as a source of purer images in plasma display panels. In the present study, PbO–B₂O₃–SiO₂ and PbO–B₂O₃–SiO₂–ZnO–Al₂O₃ were used as starting glass compositions, to which up to 25 wt% of Nd₂O₃ then was added. Increased amounts of Nd₂O₃ increased the glass transition temperature and dielectric constant of the bulk glasses and decreased the coefficient of thermal expansion. The fired thick films (around 30 μm) allowed selectively visible light to penetrate and showed deep absorption properties at 585 nm that were related to an extraneous gas from neon discharge.     

不同构形构造分布器的数值研究

Seven distributors with different configurations are designed and optimized by constructal approach. Their flow distribution performance and energy dissipation are investigated and compared by computational fluid dynamics (CFD) simulation. The reliability of CFD simulation is verified by experiments on the distributor that has all distributing rectangle channels on a plate. The results show that the symmetry of the distributing channels has decisive influence on the performance of flow distribution. Increasing the generations of channel branching will improve the flow distribution uniformity, but on the other hand increase the energy dissipation. Among all the seven constructal distributors, the distributor that has dichotomy configuration, Y-type junctions and straight intercon-necting channels, is recommended for its better flow distribution performance and less energy dissipation.     

吸附分离水体中铀的吸附材料研究新进展

铀是最危险的放射性金属之一,广泛存在于核燃料的制备、乏燃料后处理和矿石开采等生产活动所产生的含铀废水中,严重威胁水生生态系统与人类健康。吸附法处理水中的U(Ⅵ)具有便捷高效、经济和选择性好的优势。综述了近3年对水中铀吸附材料的研究新进展,介绍了无机、有机、有机无机复合和生物衍生类吸附材料的制备,结构特点,吸附性能,并对铀吸附材料的研究方向进行了展望。     

Mathematical Model for the Extraction of Neodymium from Nitrate Media using Hollow Fiber Supported Liquid Membrane Operated in a Recycling Mode

A mathematical model for facilitated extraction of Neodymium (Nd³⁺) ions from nitrate media using microporous hollow fiber supported liquid membrane (HFSLM) operated in a recycling mode is presented. Extractant N,N,N′, N′-tetraoctyl diglycolamide (TODGA) diluted with n-dodecane was used as the membrane phase. Di-n-hexyl octanamide (DHOA) has been used as a phase modifier for the extractant. The model developed is not specific to the case considered and has a more general and wide applicability. The model has been developed using equilibrium-based approach. The complexation and de-complexation reactions were assumed to be fast and at equilibrium. Mass balance equations for both acid (HNO₃) and TODGA were also incorporated in the model. It was observed that the model results are in good agreement with the experimental data when diffusivity of metal-complex (D _m ) and acid-complex (D _hm ) through the membrane phase in the pore is 6 × 10^?12 m²/s and 1.2 × 10^?10 m²/s. Once the values of D _m and D _hm are estimated by simulation for one set of data, there are no further fitting parameters in the model. The model can then be used in a truly predictive mode for all the remaining data sets.     

Diffusion of Neodymium into Sputtered Films of Tantalum Pentoxide

In this communication the diffusion of neodymium into rf-sputtered films of tantalum pentoxide (Ta₂O₅) has been investigated using the SIMS technique. The diffusion characteristics were obtained for a temperature of 1100°C, and the results showed a time-dependent diffusion coefficient that reflects a transition of the sputtered films from the amorphous to the crystalline phase. The potential for doping films of Ta₂O₅ with neodymium by diffusion, for the realization of novel active optical devices, is also discussed.     

Spectroscopic Study of Neodymium(III) in Sodium Tellurite Glass

The local environment of Nd-O in a sodium tellurite glass was elucidated as a function of Nd₂O₃ concentration, from 0.1 to 2.5 mol%, using optical spectroscopy. The Judd-Ofelt (J-O) theory was used to determine the oscillator strength parameters (J-O parameters) of the glasses. According to the J-O parameters, a significant change in the local environment of Nd-O was suggested for the glass containing 1 mol% Nd₂O₃; the asymmetry of the Nd-O crystal field was shown to be at a maximum and the bond covalency at a minimum. The results were further supported by a significant shift of the structural hypersensitive band of the glass with 1 mol% Nd₂O₃, as compared with those of the other glasses.     

Separation and Recovery of Uranium from Wastewater Using Sorbent Functionalized with Hydroxamic Acid

A newly developed hydroxamic acids functionalized acrylic based solid phase sorbent, named as poly-acryl hydroxamic acid (PHOA) is used as an extractant for the recovery of uranium from nuclear waste solution. Various parameters such as sorbent solubility in different medium, effect of various cations on U(VI) sorption, desorption performance of different eluents with respect to U(VI) sorption has been investigated in detail. U(VI) sorption behaviors of the sorbent were studied in different concentration of competitive ions such as Mg²⁺, Fe³⁺, and NO₃^? and it was found that the sorbent was capable of removing the U(VI) efficiently in the presence of high concentration of these ions.     

稀土钕(Nd)在聚氯乙烯加工中的热稳定性研究

研究表明,在用钡/锌复合物稳定剂作PVC及PVC/ABS合金的加工过程中,加入少量稀土钕化物,特别是在有能改善其初期着色性的助剂存在下,可大大提高其热稳定性。对用钕 钡/锌复合稳定剂所制备的PVC塑料及PVC/ABS合金来说,当与聚氨基甲酸酯泡沫塑料接触时,其稳定性更是出奇的好。对稀土化合物的稳定机理进行了探讨,认为稳定作用来自3个方面:变价元素、类金属皂作用和稀土络合作用。     

酞菁钕配合物的合成与元素分析及紫外分析

研究了酞菁钕配合物的合成方法及溶解性试验，并将合成所得酞菁钕配合物通过元素分析可知其纯度高；紫外分析表明酞菁钕配合物有二聚体及单体两种形式，特征吸收峰在671nm和633nm处。     

烧结钕铁硼电镀铁工艺

研究了前处理工艺对烧结钕铁硼镀铁层性能的影响。通过性能测试,确定了封孔、除油、酸洗工艺,并获得了光亮、孔隙率低、结合强度高、耐蚀性好的镀层。     

钕及其配合物对重金属铅污染植物的缓解作用

以盆栽法研究了 Pb2 +对绿豆、小白菜和菠菜的伤害以及 Nd3+的配合物 (钕 -苯氧乙酸 - 8-羟基喹啉 )对Pb2 + 伤害的缓解效应。结果表明 ,5 0 0 mg· L的 Pb Ac2 严重抑制绿豆、小白菜和菠菜的生长与代谢 ,叶面喷施 Nd3+及其配合物一次 ,能缓解 Pb2 +造成的伤害     

Effect of Aluminum and Neodymium Admixtures on Devitrification of Silica Glasses

This investigation concerned the devitrification kinetics (in the temperature range 1100° to 1500°C) of silica glasses doped with aluminum oxide (0.1 and 1.0 mol%), neodymium oxide (0.08 and 0.25 mol%), and with aluminum and neodymium oxides simultaneously, at their mutual molar ratio close to 4. The glasses were obtained by electric melting of quartz under vacuum and by the sol/gel method. On the basis of the obtained results, conclusions have been drawn concerning the mode in which the admixtures become incorporated into the silica glasses as well as the structural differences between the melted and sol/gel glasses.     

有机/杂多酸-钕配合物的合成、表征及电化学性质研究

采用水熟法合成了以2,6-吡啶二羧酸及杂多酸磷钼酸为配体的钕的新型配合物Nd（C7H5NO4）（PMo12O40）·6H2O.通过元素分析、红外光谱、紫外光谱和热重分析对其进行了结构表征,结果表明,该配合物的紫外光谱在259nm处有明显的吸收.采用循环伏安法对配合物进行电化学性质研究表明,在-0.8～-0.1 V的电势范围内,配合物具有电化学活性.