Third Phase Formation in the Extraction of Zirconium(IV) by TRPO in Kerosene

The third phase formation in the extraction of zirconium(IV) from nitric acid media by TRPO(trialkyl phosphine oxide)/kerosene was studied. The limiting organic concentrations (LOC) of Zr(IV) under various experimental conditions were determined. Low temperature and high nitric acid concentrations (> 3 M) were found to facilitate the third phase formation, while increasing the concentration of TRPO or adding phase modifier (TBP) into the organic phase resulted in increased LOC of Zr(IV). When the third phase appeared, the conductivity in the organic phase changed sharply, indicating the change of aggregating behavior in the organic phase. FT-IR spectra were used to illustrate the interaction of TRPO with HNO₃ or Zr(IV), and the composition of the two organic phases indicated by FT-IR spectra was consistent with a diluent-enriched light phase and a zirconium/TRPO-concentrated heavy phase.     

Extraction and Separation of Zr(IV) and Hf(IV) from Nitrate Medium by Some CYANEX Extractants

Abstract

A solvent extraction study has been carried out to extract and separate zirconium and hafnium from nitrate medium by using some phosphine oxide extractants (CYANEX 921, CYANEX 923, and CYANEX 925) in kerosene. The influence of the different factors affecting the extraction process was studied in detail. Apparently the rate of extraction of Zr(IV) and Hf(IV) in CYANEX 921, CYANEX 923, and CYANEX 925 is reasonably fast. The extraction increases with increasing temperature, suggesting that the reaction is endothermic. The stripping percent of Zr(IV) and Hf(IV) by 0.5 M HNO₃ from the loaded organic phase after two stages reached 97.5% and 10.2%, respectively, which lead to good separation of the two metals. Under the optimum conditions, the extraction of zirconium was about 90, 87.6, and 91.6% and separation factors equal to 17, 21.4, and 40.7 were obtained for CYANEX 921, CYANEX 923, and CYANEX 925, respectively. The results obtained reveal that 2.0 M nitric acid is the optimum acid concentration for the separation of Zr(IV) and Hf(IV) and 0.4 M CYANEX 925 performs more efficient separation compared with other organophosphorus extractants.     

Separation of Electrochemically Generated Ce(IV) from Rare Earths(III) in Nitric Acid Media by TBP Impregnated Resin

Abstract

Electro‐oxidation of Ce(III) to Ce(IV) in nitric acid media at different anode materials with high oxygen evolution overpotential was carried out. Ce(IV) nitrato complexes were adsorbed on a novel resin, based on porous silica beads with immobilized polystyrene/DVB copolymer, that was impregnated with tri‐n‐butyl phosphate (TBP). Under the studied conditions, Ce(IV) sorption increased with increasing nitric acid concentration (0.5–6 mol · dm^?3). Oxidation of sorbent by adsorbed Ce(IV) species resulting in Ce(III) release to the solution was observed and thoroughly evaluated. In spite of problems with TBP leakage (12%), column separation of pure Ce(IV) from Y(III) and La(III) was achieved in 6 mol · dm^?3 HNO₃ at 288 K. Ce(IV) breakthrough capacity was 0.48 mol · kg^?1‐TBP. Column regeneration with 0.1 mol · dm^?3 nitric acid yielded Ce solution with purity higher than 99.99 wt.% with respect to La and Y impurities.     

Synthesis,Composition, and Ion-Exchange Behavior of Thermally Stable Zr(IV) and Ti(IV) Arsenophosphates: Separation of Metal Ions

Abstract

Two new inorganic ion-exchange materials, Zr(IV) and Ti(IV) arsenophosphates, have been synthesized. They are reproducible in behavior and possess excellent thermal stability. Their tentative structures have been proposed based on pH titrations, thermogravimetry, chemical analysis, IR studies, and other ion-exchange properties. Distribution studies of some metal ions have also been made on the basis of which several useful binary separations have been achieved such as Fe(III) from VO(II), Cu(II), and Zn(II); Pb(II) from Cu(II), Hg(II), and Zn(II); Ti(IV) from UO₂(II) and Ce(IV); and Mg(II) from Sr(II) and Ba(II).     

浸渍用酚醛树脂的合成研究

采用优化工艺聚合得到的PF树脂的固含量为51.1%.数均分子量(-mn)和重均分子量为(-mw)分别为267和331,分子量主要分布在200～400之间,分散指数为1.24,表面张力较小且变化平缓,具有较好的渗透性能,同时,游离酚和游离醛的含量低.     

掺杂钕的磷酸铈独居石固化体合成研究

采用共沉淀法合成了掺杂钕元素的独居石固化体。利用X射线衍射仪,扫描电子显微镜,电子探针等现代分析技术研究了固化体的化学组成和微观结构特征。结果表明,合成了单斜晶系掺杂钕元素的独居石;固化体结构紧密,孔隙较少,晶体发育良好;由于温度影响存在0.2~1.5μm的颗粒状晶体和较大的层片状晶体;合成的固化体钕元素的掺杂量为3wt%左右。制备的固化体具有良好的机械,化学稳定性,符合高放废物(high-level waste,简称HLW)地址处置固化体的基本要求。     

Densifications and mechanical properties of single-phase Gd2Zr2O7 ceramic waste forms with improved TRPO waste load

A nitrate–citrate combustion method combined with microwave sintering was firstly employed for the rapid fabrication of the Gd₂Zr₂O₇ matrix immobilizing various amounts of simulated nuclear wastes. Phase evolutions, microstructure changes, element distributions, densification processes and mechanical properties of the as-prepared (1 – x)Gd₂Zr₂O₇·xTRPO (0.0 ≤ x ≤ 0.6) at various temperatures were investigated. Compared to the reported studies, we have increased the immobilization amount of simulated TRPO waste within a crystal structure from 45 to 60 wt%. T_d and T_g (the threshold temperatures to trigger accelerated densification and grain growth, respectively) were employed to divide the densification process into three stages. the mechanical properties and the densification stages of the (1 – x)Gd₂Zr₂O₇·xTRPO (0.0 ≤ x ≤ 0.6) ceramics sintered under microwave sintering at various temperatures were finally determined. Fine-grained (1 – x)Gd₂Zr₂O₇·xTRPO (0.0 ≤ x ≤ 0.6) ceramic waste forms with average grain size less than 200 nm and relative density higher than 90% can be obtained by microwave sintering at sintering temperature less than 1400 °C.     

Extraction and Separation of Zr(IV) From Hydrochloric Acid Solution Using Modified Silica Gel Produced From Waste Solution of Sodium Silicate

A solution of sodium silicate produced as a waste from the alkali fusion of Egyptian Rosetta zircon mineral was used for preparation of a silica gel in the pH range 6-7. The silica gel obtained was modified by phosphonic (PGMS) and sulphonic (SGMS) functionalities. The modification was confirmed by means of FT-IR, thermogravimetric analysis (TGA), energy dispersive X-ray analysis (EDX) and elemental analysis. The uptake behavior of the modified silicas towards Zr(IV) at different experimental conditions of pH, time, concentration and temperature was studied. Kinetic and thermodynamic parameters of uptake process were reported. The regeneration of the loaded silicas was also carried out.     

Solvent Extraction Behavior of Plutonium (IV) Ions in the Presence of Simple Hydroxamic Acids

Abstract

Formo‐ and aceto‐hydroxamic acids are very effective reagents for stripping Pu(IV) ions from a tri‐butyl phosphate phase into nitric acid. Distribution data for Pu(IV) in the presence of these hydroxamate ions have been obtained and trends established. The affinity of aceto‐hydroxamic acid for Pu(IV) ions and its selectivity over U(VI) ions is demonstrated by the values of the stability constants in HClO₄. These data support the applications of simple hydroxamic acids in advanced Purex‐type solvent extraction systems.     

Sorption Behavior of In(III) Ions onto Cation-Exchange Carboxylic Resin in Aqueous Solutions: Batch and Column Studies

Indium and its compounds have numerous industrial applications in the manufacture of liquid crystal displays and semiconductors. They are considered hazardous substances. This article reports the research into the recovery of In(III) from aqueous solution by sorption. Cation-exchange carboxylic resin (D155 resin) was used as a sorbent for indium(III) ions extraction in this research. The factors of parameters, such as pH, kinetics, temperature and sorption isotherm, and column experiment were investigated. In batch system, D155 resin exhibited the highest In(III) ion uptake as 279 mg/g at 298 K with a pH value 5.00. The sorption data matched the Langmuir isotherms very well. The thermodynamic parameter ΔG was negative, and this result indicated that the sorption of In(III) ions on D155 resin was spontaneous. Furthermore, the positive value of ΔH showed that the sorption was endothermic in nature. In(III) ions can be eluted with 0.5 mol/L HCl solution. The Thomas model was applied to experimental column data to determine the characteristic parameters of the column which is useful for process design.     

膦(磷)类萃取剂浸渍树脂吸附重稀土的性能

利用静态法研究了5种不同膦(磷)类萃取剂的浸渍树脂在盐酸介质中对重稀土的吸附行为. 结果表明,Cyanex272与膦(磷)类萃取剂组成的双萃取剂的浸渍树脂在同等实验条件下比单一Cyanex272萃取剂的浸渍树脂对重稀土具有更好的吸附性,其中以Cyanex272与P507, Cyanex302, Cyanex923和TBP分别按体积比1:1, 5:1, 1:1, 2:1混合为最优. 吸附最佳pH值在3.0~4.0之间,吸附平衡时间为50 min,升高温度对吸附有利. 在相同实验条件下,5种浸渍干树脂Cyanex272, Cyanex272-P507, Cyanex272-Cyanex302, Cyanex272-Cyanex923, Cyanex272-TBP对重稀土的饱和吸附容量分别为20.04, 25.37, 21.87, 22.16, 38.48 mg/g.     

Screening of ATP hydrolysis by Zr(IV) and Eu(III) complexes

The dephosphorylation of adenosine triphosphate (ATP) by various zirconium (IV) and europium (III) complexes is described. Release of phosphate was followed by an automated, robotics-based colorimetric assay which is compatible with the presence of these high-valent metal ions.     

锆-钕-氧纳米材料的合成及其可见光响应的光催化性能

采用熔盐辅助的溶胶–凝胶法成功合成了锆–钕–氧(Zr–Nd–O)系列纳米材料。利用 X 射线衍射、X 射线能量散射谱以及扫描电子显微镜对所得产物的物相、组成以及形貌进行了表征。通过染料水溶液在可见光条件下的光催化降解实验对 Zr–Nd–O 系列纳米材料的光催化性能进行了评价。结果表明：所得Zr0.8Nd0.2O2–δ纳米材料对罗丹明B和亚甲基蓝水溶液具有很好的可见光催化降解性能,在可见光照射150 min后的最大降解率分别为93.4%和83.0%。反应机理研究表明,其优异的光催化性能来源于其特殊的缺陷结构、较小的颗粒尺寸(25～65 nm)和较大的比表面积(54.88 m2/g)。     

由脲醛树脂制备炭材料及其对金属离子的吸附性能

以脲醛树脂为前躯体,在氮气气氛中炭化获得炭吸附材料ACUF,对其结构、表面性质及形貌进行了分析,采用静态法考察了700℃下炭化所得材料ACUF700对不同金属离子的吸附性能. 结果表明,ACUF保留了大量的胺基活性基团,并具有发达的微孔结构. ACUF700的比表面积达702.3 m2/g,平均孔径为2.044 nm,对Pb2+, Cu2+, Fe3+和La3+均有良好的吸附性能,吸附容量分别达39.7, 37.0, 13.0和10.5 mg/g;并具有良好的再生性和重复使用性,循环使用5次后吸附容量变化很小. 吸附过程符合准二级动力学方程,可用Langmuir吸附等温方程描述.     

Separation and Recovery of Silver(I) Ions from Base Metal Ions by Thiourea- or Urea-Formaldehyde Chelating Resin

Abstract

In the present work, thiourea-formaldehyde (TF) and urea-formaldehyde (UF) chelating resins have been synthesized and they have been used in the adsorptions of Ag(I), Cu(II), and Zn(II) metal ions by batch and column methods. The effect of initial acidity of Ag(I) solution and the adsorption capacities of TF and UF resins by batch method and the separation of Ag(I) ions from Cu(II) and Zn(II) base metal ions by the column method were examined experimentally. The adsorption capacities of TF and UF resins were found as 58.14 and 47.39 mg Ag(I)/g by batch method and 30.7 and 4.66 mg Ag(I)/g, 0.80 and 0.121 mg Cu(II)/g, and under 0.002 mg Zn(II)/g by the column method, respectively. It was found that Ag(I) ions showed higher affinity towards TF resin than UF resin, compared with Cu(II) or Zn(II) ions, and Ag(I) could be separated more effectively by TF resin from Cu(II)and Zn(II) ions.     

Internal Alkene Hydroaminations Catalyzed by Zirconium(IV) Complexes and Asymmetric Alkene Hydroaminations Catalyzed by Yttrium(III) Complexes

The thiophosphinic amide 2 was prepared in 68 % yield by the reaction of 2,2‐dimethyl‐1,3‐propanediamine with diisopropylchlorophosphine followed by the addition of sulfur. Attachment of the proligand 2 to zirconium was achieved by direct metalation with Zr(NMe₂)₄ in benzene‐d₆ or toluene‐d₈ to afford complex 3 via elimination of dimethylamine. The neutral Zr(IV) complex 3 has been shown to be an effective precatalyst for intramolecular alkene hydroaminations that provide cyclic amines in good to excellent yields. A variety of chiral ligands ( 20 , 22 , 24 , and 25 – 30 ) were prepared for asymmetric internal alkene hydroaminations. Metalation of chiral ligands to yttrium was accomplished with Y[N(TMS)₂]₃ in benzene‐d₆ or toluene‐d₈ to give complexes. Treatment of 7 with 5 mol % of 33 in benzene‐d₆ (25 °C, 18 h) or toluene‐d₈ (25 °C, 15 h) afforded 2,4,4‐trimethylpyrrolidine 14 in 95 % yield (61 % ee).     

硅钛酚醛树脂的合成和表征

采用烷氧基硅烷单体和钛酸四丁酯(TBOT)进行水解缩合,制得元素有机硅树脂聚钛硅氧烷(TiSi),再将聚钛硅氧烷与酚醛树脂(PF)进行脱水缩合,制得元素有机硅改性酚醛树脂(TiSiP)。利用红外光谱对得到的TiSi、PF和TiSiP的结构进行了表征,利用TG对TiSiP树脂的耐温性能进行了考察。所合成的树脂经180℃固化3h后,在空气气氛中300℃时开始出现明显的热失重,700℃时的残留率为64%。     

Elution Behavior of Metal Ions with Mixed Glycine-Nitric Acid Eluents in Dowex 50W-X8 Column: Separation of Th(IV), Ce(IV), Bi(III), Fe(III), and Al(III)

Abstract

Distribution coefficients (K) determined by the batch technique in acidic glycine media using Dowex 50W-X8 cation exchanger (H⁺?form, 100–200 mesh size) revealed that this medium can effectively be employed to separate a number of tetravalent and trivalent metal ions from bivalent metal ions. In fixed glycine (0.40 M) and varying concentration of nitric acid (0.10 to 1.0 M), a number of mixtures containing two or three metal ions were resolved on columns using about 8 g of exchanger. In 0.40 M glycine-1.0 M HNO₃ medium, Th(IV)/Ce(IV) were separated from Al(III)/Fe(III)/Bi(III)/Co(II)/Ni(II)/Cu(II)/Zn(II)/Cd(II)/Hg(II)/Pb(II)/Ag(I) and also Al(III)/Bi(III) from a number of divalent metal ions. In 0.40 M glycine-0.50 M HNO₃ medium, the resolution of following ternary mixtures were also achieved: Th(IV)/Ce(IV)-Al(III)/Bi(III)-Fe(III)/Co(II)/Ni(II)/Cu(II)/Zn(II)/Cd(II)/Hg(II)/Pb(II)/Ag(I). Th(IV)/Al(III)/Fe(III)/Bi(III) were also separated from other divalent metal ions in 1.60 M glycine-0.50 M HNO₃ medium. The values of K, elution characteristics of metal ions, elution curves, and the results of the resolution of a number of mixtures of metal ions along with standard deviations are reported.