Separation of tungsten and molybdenum with solvent extraction using functionalized ionic liquid tricaprylmethylammonium bis(2,4,4-trimethylpentyl)phosphinate

Functionalized ionic liquids(FILs) as extractants were employed for the separation of tungsten and molybdenum from a sulfate solution for the first time. The effects of initial pH, extractant concentration, metal concentrations in the feed were comprehensively investigated. The results showed that tricaprylmethylammonium bis(2,4,4-trimethylpentyl)phosphinate([A336][Cyanex272]) could selectively extract W over Mo at an initial pH value of 5.5; the best separation factor βW/Mo of 25.61 was obtained for a solution with low metal concentrations(WO_3: 2.49 g/L, Mo: 1.04 g/L). The [A336][Cyanex272] system performed effectively for solutions of different W/Mo molar ratios and different metal ion concentrations in the feed. The chemical reaction between [A336][Cyanex272] and W followed the ion association mechanism,which was further proved by the Fourier-transform infrared(FTIR) spectra of loaded [A336][Cyanex272] and the free extractant. The stripping experiments indicated that 95.48% W and 100.00% Mo were stripped using a 0.20 mol/L sodium hydroxide solution. Finally, the selective extractions of W and Mo from two synthetic solutions of different high metal concentrations were obtained; the separation factor βW/Mo reached 23.24 and 17.59 for the first and second solutions, respectively. The results suggest the feasibility of [A336][Cyanex272] as an extractant for the separation of tungsten and molybdenum.     

Process development for the direct solvent extraction of nickel and cobalt from nitrate solution: aluminum,cobalt, and nickel separation using Cyanex 272

A direct solvent extraction(DSX) process for purifying nickel and cobalt from the nitric acid leach solution of nickel laterite ores was conceived and experimentally probed. The proposed process consists of two solvent extraction(SX) steps but with only one extractant — bis(2,4,4-trimethylpentyl)phosphinic acid(Cyanex? 272) — used in both steps. The first extraction step involved the removal of aluminum and zinc, whereas the second extraction step involved the separation of cobalt along with manganese from nickel. The experimental results showed essentially quantitative removal of aluminum(97%) and zinc(99%) in a single extraction stage using 20vol% Cyanex 272 at pH 2.1. Some cobalt(32%) and manganese(55%) were co-extracted but were easily scrubbed out completely from the loaded organic phase using dilute sulfuric acid at pH ≤ 1.38. Cobalt and manganese in the first extraction raffinate were extracted completely in four extraction stages at staggered pH values of 4.0, 4.4, 4.5, and 4.0 in the first, second, third, and fourth stages, respectively, using also 20vol% Cyanex 272. A small amount of nickel(up to 6.6%) was co-extracted but was easily scrubbed out completely with dilute sulfuric acid at pH 2.0. A flow diagram showing the input and output conditions and the metals separated under the deduced optimum conditions is presented.     

Extraction and separation of nickel and cobalt from saprolite laterite ore by microwave-assisted hydrothermal leaching and chemical deposition

Extraction and separation of nickel and cobalt from saprolite laterite ore were studied by using a method of microwave-assisted hydrothermal leaching and chemical deposition. The effects of leaching temperature and time on the extraction efficiencies of Ni2+ and Co2+ were investigated in detail under microwave conditions. It is shown that the extraction efficiencies of Ni2+ and Co2+ from the ore pre-roasted at 300℃ for 5 h were 89.19% and 61.89% when the leaching temperature and time were about 70℃ and 60 min, respectively. For the separation process of Ni and Co, the separation of main chemical components was performed by adjusting the pH values of sulfuric leaching solutions using a NaOH solution based on the different pH values of precipitation for metal hydroxides. The final separation efficiencies of Ni and Co were 77.29% and 65.87%, respectively. Furthermore, the separation efficiencies of Fe of 95.36% and Mg of 92.2% were also achieved at the same time.     

Universal thermodynamic model of calculating the mass action concentrations of omponents in a ternary strong electrolyte aqueous solution and its application in the NaCl-KCl-H2O system

A universal thermodynamic model of calculating the mass action concentrations of components in a ternary strong electrolyte aqueous solution has been developed based on the ion and molecule coexistence theory,and verified in the NaCl-KCl-H₂O ternary system at 298.15 K. To compare the difference of the thermodynamic model in binary and ternary strong electrolyte aqueous solutions,the mass action concentrations of components in the NaCl-H₂O binary strong electrolyte aqueous solution were also computed at 298.15K. A transformation coefficient was required to compare the calculated mass action concentration and reported activity because they were obtained at different standard states and concentration units. The results show that the transformation coefficients between calculated mass action concentrations and reported activities of the same components change in a very narrow range. The calculated mass action concentrations of components in the NaCl-H₂O and NaCl-KCl-H₂O systems are in good agreement with the reported activities. This indicates that the developed thermodynamic model can reflect the structural characteristics of solutions,and the mass action concentration also strictly follows the mass action law.     

Preparation of 3-D porous fibroin scaffolds by freeze drying with treatment of methanol solutions

In this study, silk scaffolds with appropriate porous structures were prepared by adjusting solution concentrations and providing treatment with methanol solutions in the way of freeze drying. The effects of the preparation conditions on the microstructures and properties of the scaffolds were discussed. Fibroin solutions with different concentrations of 4, 6, 8, 10 wt% were used respectively to prepare the scaffolds. The effects of the addition of 20 vol% methanol before or after freeze drying to the 4 wt% fibroin solution were investigated. As demonstrated by Scanning Electron Microscope (SEM), the fib-roin scaffolds prepared without methanol had porous microstructures composed of thin sheets, and the sizes of the pores decreased with the increase of the fibroin solution concentrations, while the scaffolds prepared in the presence of methanol showed porous microstructures formed by fine-particle aggregates. The porosities and mechanical properties of the prepared fibroin scaffolds under different conditions were tested. The crystalline structures and conformations of the fibroin scaffolds were detected by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD).     

A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary solution

A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO₄-H₂O and NaF-H₂O binary solutions and NaClO₄-NaF-H₂O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory (IMCT). A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO₄-H₂O and NaF-H₂O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO₄-NaF-H₂O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H₂O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.     

Process development for the direct solvent extraction of nickel and cobalt from nitrate solution: aluminum,cobalt, and nickel separation using Cyanex 272

A direct solvent extraction (DSX) process for purifying nickel and cobalt from the nitric acid leach solution of nickel laterite ores was conceived and experimentally probed. The proposed process consists of two solvent extraction (SX) steps but with only one extractant-bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex® 272)-used in both steps. The first extraction step involved the removal of aluminum and zinc, whereas the second extraction step involved the separation of cobalt along with manganese from nickel. The experimental results showed essentially quantitative removal of aluminum (>97%) and zinc (>99%) in a single extraction stage using 20vol% Cyanex 272 at pH 2.1. Some cobalt (32%) and manganese (55%) were co-extracted but were easily scrubbed out completely from the loaded organic phase using dilute sulfuric acid at pH ≤ 1.38. Cobalt and manganese in the first extraction raffinate were extracted completely in four extraction stages at staggered pH values of 4.0, 4.4, 4.5, and 4.0 in the first, second, third, and fourth stages, respectively, using also 20vol% Cyanex 272. A small amount of nickel (up to 6.6%) was co-extracted but was easily scrubbed out completely with dilute sulfuric acid at pH 2.0. A flow diagram showing the input and output conditions and the metals separated under the deduced optimum conditions is presented.     

Coupling effects of tungsten and molybdenum on microstructure and stressrupture properties of a nickel-base cast superalloy

In order to comprehensively understand the forming mechanism of abnormal phases solidified in a nickel-base cast superalloy with additives of tungsten and molybdenum, the coupling effects of W and Mo on the microstructure and stress-rupture properties were investigated in this paper. The results indicated that the precipitation of primary α-(W, Mo) phase depended tremendously on the amount of W and Mo addition. When the total amount of W and Mo was greater than 5.79 at%, α-(W, Mo) phase became easily precipitated in the alloy.With increasing of Mo/W ratio, the dendrite-like α-(W, Mo) phases were apt to convert into small bars or blockylike phases at the vicinities of γ′/γ eutectic. The morphological changes of α-(W, Mo) phase can be interpreted as the non-equilibrium solidification of W and Mo in the alloy. Since the large sized α-(W, Mo) phase has detrimental effects on stress-rupture properties in as-cast conditions, secondary cracks may mainly initiate at and then propagate along the interfaces of brittle phases and soft matrix. During exposing at 1100 ℃ for 1000 h, the α-(W, Mo) phases transformed gradually into bigger and harder M_6C carbide, which results in decreasing of stress-rupture properties of the alloy. Finally, the alloy with an addition of 14W-1Mo(wt%) maintained the longest stress lives at high temperatures and therefore it revealed the best microstructure stability after 1100 ℃/1000 h thermal exposure.     

Mathematical modeling of salt-gradient ion-exchange simulated moving bed chromatography for protein separations

The salt-gradient operation mode used in ion-exchange simulated moving bed chromatography (SMBC) can improve the efficiency of protein separations. A detailed model that takes into account any kind of adsorption/ion-exchange equilibrium, salt gradient, size exclusion, mass transfer resistance, and port periodic switching mechanism, was developed to simulate the complex dynamics. The model predictions were verified by the experimental data on upward and downward gradients for protein separations reported in the literature. All design and operating parameters (number, configuration, length and diameter of columns, particle size, switching period, flow rates of feed, raffinate, desorbent and extract, protein concentrations in feed, different salt concentrations in desorbent and feed) can be chosen correctly by numerical simulation. This model can facilitate the design, operation, optimization, control and scale-up of salt-gradient ion-exchange SMBC for protein separations.     

Effect of welding process on the microstructure and properties of dissimilar weld joints between low alloy steel and duplex stainless steel

To obtain high-quality dissimilar weld joints, the processes of metal inert gas (MIG) welding and tungsten inert gas (TIG) welding for duplex stainless steel (DSS) and low alloy steel were compared in this paper. The microstructure and corrosion morphology of dissimilar weld joints were observed by scanning electron microscopy (SEM); the chemical compositions in different zones were detected by energy-dispersive spectroscopy (EDS); the mechanical properties were measured by microhardness test, tensile test, and impact test; the corrosion behavior was evaluated by polarization curves. Obvious concentration gradients of Ni and Cr exist between the fusion boundary and the type II boundary, where the hardness is much higher. The impact toughness of weld metal by MIG welding is higher than that by TIG welding. The corrosion current density of TIG weld metal is higher than that of MIG weld metal in a 3.5wt% NaCl solution. Galvanic corrosion happens between low alloy steel and weld metal, revealing the weakness of low alloy steel in industrial service. The quality of joints produced by MIG welding is better than that by TIG welding in mechanical performance and corrosion resistance. MIG welding with the filler metal ER2009 is the suitable welding process for dissimilar metals jointing between UNS S31803 duplex stainless steel and low alloy steel in practical application.     

新型萃取剂Cyanex272在液膜分离技术中的应用

介绍了新型磷类萃取剂Ｃｙａｎｅｘ２７２在液膜分离，预浓和提取金属离子中的应用，并提出了有关该项研究的看法。     

汞与铁、镓、铑、铈和锌的绿色析相萃取富集和分离研究

研究水-溴化钾-正丙醇-硫酸铵体系绿色析相萃取汞的行为及与一些金属离子分离的条件.结果表明,硫酸铵能使正丙醇的水溶液分成两相,HgBr24-与质子化正丙醇(C3H7OH2+)形成的缔合物[HgBr24-][C3H7OH2+]2能被正丙醇相完全萃取.当溶液中溴化钾、硫酸铵和正丙醇的浓度分别为7.0 mmol/L,200 g/L和30%(v/v)时,Hg2+的萃取率达到97.3%以上,而Fe2+、Ga3+、Rh3+、Ce3+和Zn2+基本不被萃取,实现了Hg2+与上述金属离子的分离.     

Electronic properties and stabilities of methoxy-substituted Lindqvist polyoxometalates [Nb2W4019CH3]3- by DFT

The electronic properties and stabilities of five [Nb2W4O18OCH3]3-isomers have been investigated using a density functional theory method.The results show that the isomer with the methoxy group occupying a bridging position between two tungsten atoms(two tungsten atoms in the plane that contains two niobium atoms) in the [Nb2W4O18OCH3]3-framework is the most stable isomer in acetonitrile.The stability of the one-electron-reduced isomers changes little.The most stable one-electron-reduced isomer has the methoxy group occupying a bridging position between niobium atoms in the [Nb2W4O18OCH3]4-framework.The M-Ob(M = Nb,W;b denotes bridging) bond lengths in anions in which the metal atoms are connected by a methoxy group are longer than those in [Nb2W4O19]4-.The highest occupied molecular orbitals(HOMO) in [Nb2W4O19]4-mainly delocalize over the bridging oxygen atoms of two niobium atoms and two tungsten atoms located in the equatorial plane,and the bridging oxygen atoms on the axial surface.The lowest unoccupied molecular orbitals(LUMO) of [Nb2W4O19]4-are mainly concentrated on the tungsten atoms and antibonding oxygen atoms.Methoxy substitution modifies the electronic properties of the [Nb2W4O18OCH3]3-isomers.The HOMOs in the five isomers formally delocalize over the bridging oxygen atoms,which are distant from the surface containing the methoxy group and four metal atoms.The LUMOs delocalize over the d-shells of the four metal atoms that are close to the methoxy group,and the p-orbitals of oxygen.One-electron reduction occurred at the tungsten atoms,not the niobium atoms.     

锡与钼、镓、铈和钨的绿色析相萃取富集和分离研究

在硫酸铵存在下,乙醇水溶液能够分为醇/水两相,在分相过程中,C2H5OH+2与[Sn(SCN)5~6][(5~6)-4]-生成的[C2H5OH2]1~2[Sn(SCN)5~6]三元缔合物能被乙醇相萃取,使Sn(Ⅳ)与Mo(Ⅵ)、Ga(Ⅲ)、Ce(Ⅲ)和W(Ⅵ)离子分离.该方法在微量锡的分离和富集分析中有一定的实用价值.     

钨(Ⅵ)与3,5-二溴-4-偶氮间苯二酚苯基荧光酮显色反应的研究

在混合型非离子表面活性剂TritonX-100和乳化剂OP存在下,研究了3,5-二溴-4-偶氮间苯二酚苯基荧光酮(DBARPF)与钨(Ⅵ)显色反应的光度特征,建立了光度法测定微量钨(Ⅵ)的新方法.在0.32mol/LHCl介质中,DBARPF与钨(Ⅵ)及表面活性剂形成胶束络合物,最大吸收波长位于538nm处,混合型非离子表面活性剂有一定的增敏作用,络合物表观摩尔吸光系数为2.92×105L·mol-1·cm-1,W(Ⅵ)与DBARPF形成稳定的1∶4水溶性络合物.钨(Ⅵ)含量在0～320μg/L范围服从比尔定律,大多数金属离子不影响钨(Ⅵ)的测定,尤其是与钨(Ⅵ)化学性质相似的钼(Ⅵ)的干扰可以有效地消除.该分析方法可用于合金钢中微量钨的测定.     

从高杂钨细泥制取高纯仲钨酸铵的新工艺(英文)

研究了一个从低品位钨原料生产高纯仲钨酸铵(APT)的新的湿法冶金过程。流程包括两段逆流浸出;净化除Sn,Si,As,P;溶剂萃取及吸附法分离钨与钼;钨的溶剂萃取;湿法多段脱浮等工序。这一新工艺适于处理Si,As,P,Mo,Sn,Mn,Ca等含量变化很大的原料。当结晶率大于90%时,APT中的杂质总量小约110ppm,三氧化钨的工艺总收率大于90%。     

钼铁厂固体废物浸出液中钼的测定

用石墨炉原子吸收光谱法测定钼铁厂固体废物浸出液中的钼,当选择合适实验条件的情况下,钼的测定灵敏度较高,校准曲线的相关系数大于0.999,精密度较好,方法的检出下限为0.6μg/L,定量测定范围2.4～60μg/L,测定结果令人满意.     

离子液体催化废聚碳酸酯的乙醇醇解反应

以合成的离子液体氯化1-丁基-3-甲基咪唑（[Bmim][Cl]）为催化剂,对废聚碳酸酯（PC）乙醇醇解回收双酚A（BPA）和碳酸二乙酯（DEC）反应进行了研究.考察了反应温度、乙醇用量、离子液体用量和反应时间等因素对反应结果的影响.结果表明：在反应温度为130℃,反应时间为2h,n（C2H5OH）：n（PC）=6∶1,m（[Bmim][Cl]）：m（PC）=0.5∶1的较佳条件下,PC降解率为100％,BPA收率＞95％,DEC收率＞91％.采用IR技术对所得产物进行了表征.