Acidity and Rare Earth Concentration Effects on Ytterbium Purification by an Electrolysis Reduction in H2SO4 Medium

Ytterbium purification by an electrolysis reduction in sulfuric acid medium was investigated without nitrogen or argon protection, in which Ru-Ir-Ti alloy nets and mercury were used as anode and cathode, respectively. How the conditions such as the acidities of cathode and anode solutions, and the concentration of Yb（ Ⅲ ） to affect the circuit and ratio of Yb（ Ⅱ ）/Yb （ Ⅲ ） in electrolysis reduction were studied.     

Extraction mechanism of cerium（Ⅳ） in H2SO4/H3PO4 system using bifunctional ionic liquid extractants

The extraction of Ce（Ⅳ） in H2SO4/H3PO4 system was investigated systematically using bifunctional ionic liquid extractants（Bif-ILES） [A336][P507],[A336][P204] and [A336][C272] in n-heptane.The effects of H2SO4 concentration,extractant concentration and salting-out agent concentration were observed in detail.The extraction mechanism of Ce（Ⅳ） in H2SO4/H3PO4 system was obtained.The comparison with other extractants such as Cyanex923,TBP was also studied.Thermodynamic functions of the extraction reaction were calculated,showing that the extraction was an exothermic process.The separation of Ce（Ⅳ） from RE（Ⅲ） and Th（Ⅳ） was also investigated.The result indicated that Ce（Ⅳ） could be selectively extracted in this system.CePO4 nanoparticles were obtained in the process of stripping using H2O2 in H2SO4/H3PO4 system.X-ray diffraction（XRD）,scanning electron microscopy（SEM） and spectroscopy were adopted for the characterization of the sample.     

Synthesis of 2, 6-Bis（1＇-Phenyl-3＇-Methyl-5＇-Oxopyrazole-4＇） Pyridinediacyl and Its Solid-Liquid Extraction Behavior for Ce（Ⅲ）

β-diketone type chelating ligands have high coordinative activity and selectivity, and are widely applied in analytical ehemistry. In order to obtain profounder understanding to the properties of bis(4-aeylpyrazolone-5), A new 4-aeylpyrazol-5-one derivative (H2BPMPP) was syntheszed, whieh eontains a heteroeyelie ring between two 1-phenyl-3-methyl-4-aeylpyrazol-5-one rings. The new compound was eharaeterized by element analyses, UV, IR and ^1H NMR speetra. The equilibrium of the keto-enol tautomerism was studied. The results show that a lower dieleetric constant of solvent favors the enol form whieh has a higher λmax.Due to speeial merits of paraffin wax, the solidliquid extraetion behavior of Ce(Ⅲ) with molten paraffin wax as a diluent was also investigated at higher temperature. The value of the pH1/2 was 3.19 and the value of logKex was 3.467. The ehemieal eomposition of the complex was obtained by the slope analysis method.     

Synergistic extraction of cerium from sulfuric acid medium using mixture of 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester and Di-（2-ethyl hexyl） phosphoric acid as extractant

Synergistic extraction of cerium(IV) from sulfuric acid medium using mixture of 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester(HEH/EHP, HL) and Di-(2-ethyl hexyl) phosphoric acid (HDEHP, HA) as extractant was investigated. The results indicated that the maximum synergistic enhancement coefficients were obtained at the mole fraction of HEH/EHP=0.6, and cerium(IV) was extracted into organic phase in the form of Ce(SO4)0.5HL2A2. A cation exchange mechanism was proposed for the synergistic extraction of Ce(IV). The equilibrium constants and thermodynamic functions such as △G, △H, and △S were determined in the extraction of Ce(IV) from sulfuric medium using mixture of HEH/EHP and HDEHP.     

Extraction and Stripping of Ytterbium (Ⅲ) from H2SO4 Medium by Cyanex 923

The extraction and stripping of ytterbium(Ⅲ) from sulfuric acid medium using Cyanex 923 in heptane solution was investigated. The effects of extractant concentration, pH and sulfate ion as well as stripping agents, acidity and temperature on the extraction and stripping were studied. The equilibrium constants and thermodynamic parameters, such as ΔH (10.76 kJ·mol-1), ΔG (-79.26 kJ·mol-1) and ΔS (292.41 J·K-1·mol-1), were calculated. The extraction mechanism and the complex species extracted were determined by slope analysis and FTIR spectra. Furthermore, it was found that the extraction of Yb (Ⅲ) from sulfuric acid medium by Cyanex 923 increased with pH, concentration of SO42-, HSO4-, and extractant concentration, and approximately a quantitative extraction of Yb(Ⅲ) was achieved at an equilibrium pH near 3.0, and the extracted complex was YbSO4(HSO4)·2Cyanex923(o).     

Kinetic Study of Ce~(4 )Extraction with Cyanex 923

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Effect of diluents on the extraction of praseodymium and samarium by Cyanex 923 from acidic nitrate medium

The solvent extraction of Pr(Ⅲ) and Sm(Ⅲ) with trialkyl phosphine oxide(Cyanex 923) in chloroform,carbon tetrachloride,n-octane,cyclohexane,1,2-dichloroethane,benzene,toluene,xylene and nitrobenzene from acidic nitrate medium was investigated.On the basis of slope analysis data,the composition of the extracted species was determined as(M(NO3)3?2CY923),CY923 refers to Cyanex 923.The values of the equilibrium constants and the separation factors were calculated.The effect of the diluents on the metal extracti...     

A comparative study on extraction of Fe(III) from chloride leach liquor using TBP, Cyanex 921 and Cyanex 923

A comparative study on extraction of Fe(III) from the HCl leach liquor of low grade iron ore tailings has been carried out using Tri-n-butyl phosphate (TBP), Cyanex 921 and Cyanex 923 in distilled kerosene. The percentage extraction of iron increased with increasing HCl and extractant concentrations. The extracted species in each case was found to be HFeCl₄·S. The extraction isotherms for the above extractants indicated quantitative extraction of Fe(III) in 3-stages at O:A ratio of 3:2 with TBP, and in 2-stages at O:A ratio of 1:1 with Cyanex 921 and Cyanex 923. The stripping studies of the loaded organic phases were carried out with 0.4 M HCl. The stripping isotherms indicated 2-stages at O:A ratio of 5:2 for TBP, and 3-stages at O:A ratio of 2:3 for Cyanex 921 and Cyanex 923. From the extraction studies, the extraction efficiency of the extractants for Fe(III) was in the order TBP < Cyanex 921 < Cyanex 923. Although Cyanex 923 was found to be the best extractant, the percentage stripping of Fe from the loaded Cyanex 923 was the least. The stripping of Cyanex 923 was 94.9%, but with TBP and Cyanex 921, it was 99.8% and > 99.9%, respectively.     

Thermodynamic and application study of complicated extraction system Ce(IV)–HF–H3BO3–H2SO4 using Cyanex 923

This article aims to reduce the environmental pollution while maximizing the recovery of REEs as well as associate resource-fluorine (F) from bastnaesite. This paper investigates the extraction equilibrium process and mechanism of Ce(IV)–HF–H₃BO₃–H₂SO₄ system using Cyanex 923. Extraction equilibrium process of different systems, including HF–H₂SO₄, H₃BO₃–HF–H₂SO₄, and Ce(IV)–HF–H₂SO₄, were studied in detail and the corresponding extraction mechanisms were also determined. It is noteworthy that a synergistic effect between B–F and an antagonistic effect between Ce(IV)–F were discovered first in the extraction process by Cyanex 923. Besides, H₃BO₃ is found to be able to promote the extraction of F in quantitation by Cyanex 923. FTIR and ¹¹B and ¹⁹F NMR were adopted to characterize the different loaded organic phase. Based on these results, the extraction mechanism of complicated system Ce(IV)-HF-H₃BO₃–H₂SO₄ was further determined. Besides, the effect of H₃BO₃ on the extraction and stripping of Ce(IV) in complicated system was studied. Moreover, it shows that the addition of H₃BO₃ has nothing to do with the purity of obtained CeF₃ particle from bastneasite liquor in the practical system. Adding H₃BO₃ into bastnaesite leach liquor, on the one hand, will be beneficial for the recovery yield of Ce and F. On the other hand, it can avoid from environmental pollution caused by emission of F-containing waste water as well as reducing the waste residue.     

硫酸体系中Cyanex272的萃镓性能研究

开展了硫酸体系中Cyanex272的萃镓性能研究,详细考察了萃取与反萃过程条件参数对镓萃取与反萃的影响,绘制了萃取与反萃等温线,并模拟了多级逆流试验。结果表明,含290 mg/L Ga~(3+),pH=2.0的硫酸镓溶液,采用有机相体积分数为15%Cyanex272+85%磺化煤油,控制O/A=1∶4,萃取温度25℃,萃取时间10min,经4级逆流萃取,镓萃取率为99.50%;负载镓有机相,用100g/L H_2SO_4溶液反萃,控制O/A=10∶1,反萃温度25℃,反萃时间10min,经4级逆流反萃,镓反萃率为98.11%,镓富集于反萃液中,富集倍数近40倍。经中和沉淀、焙烧后,可得到氧化镓产品。     

Extraction Mechanism of La^3 ＋ from Hydrochloric Acid Solution Using Cyanex 302

The solvent extraction of La3 from hydrochloric acid solutions was investigated using bis (2, 4, 4-trimethylpentyl) monothiophosphinic acid (Cyanex 302, HL) as an extractant. The effect of .equilibrium of aqueous acidity on extraction of La^3 using Cyanex 302 in different diluents was discussed. The effects of extractant concentration and chloride ion on the extraction reaction were also studied. Stoichiometry of the extraction reactions and the nature of metal complexes formed were determined using slope analysis technique and IR measurement.     

Syntheses,characterization, and luminescence of two lanthanide complexes [Ln2（acetate）6（HeO）4]·4H2O （Ln=Tb（1）, Sm（2））

Two dinuclear compounds [Ln2（acetate）6（H2O）4]-4H2O （Ln=Tb（1）, Sm（2）） were obtained by the hydrothermal reaction of Ln2O3 with malonic acid at 150 ℃. Both compounds were characterized by elemental analyses, infrared spectra, and single crystal X-ray diffraction. The results showed that complexes 1 and 2 were isomorphous and crystallize in triclinic space group P 1. The coordination geometry around Ln（Ⅲ） ions in the complexes 1 and 2 was a distorted tricapped trigonal prism with a nine coordination. In the crystal, the molecular organization was further stabilized by well-defined weak hydrogen bonding interactions between the neutral dinuclear molecular units that led to the formation of a three-dimensional network. The fluorescence properties of the two complexes 1 and 2 in organic solvents were also studied. The results show that the ligand acetate favored energy transfer to the emitting energy level of Tb（Ⅲ） in complex 1. Some factors that influence the fluorescent intensity were also discussed in the article.