一元烷基磷(膦)酸酯萃取钴,镍反应中取代基空间效应的经验参数

本文在考察一元烷基磷(膦)酸酯萃取钴、镍反应平衡常数与取代基结构的定量关系的基础上,提出了酸性磷(膦)酸酯萃取钴、镍反应中反映取代基结构空间效应为主的经验参数EPA[Co]和EPA[NI],这些新标度的建立,不仅使我们可用关系式来描述萃取钴、镍的反应性与取代基结构效应的关系,而且也为选择高效镍、钴分离萃取剂提供了新途径。     

二(2-乙基己基)膦酸对镉(Ⅱ)、钴(Ⅱ)和镍(Ⅱ)的萃取平衡

溶剂萃取;二(乙基己基)膦酸;二(2-乙基己基)膦酸对镉(Ⅱ)、钴(Ⅱ)和镍(Ⅱ)的萃取平衡     

酸性磷型萃取剂的结构与萃取钴,镍性能关系的研究

考察了一系列二烷基磷酸酯,烷基膦酸单烷基酯和二烷基膦酸对钴(Ⅱ)、镍(Ⅱ)的萃取性能。应用相关分析法探讨了萃取性能与萃取剂分子中取代基的极性效应和空间效应之间的关系。并依据萃合物立体构型的差异解释了萃取剂结构对萃取钴、镍的不同影响。     

二烷基二硫代次膦酸的合成

以PSCl3和卤代烷为原料,经格氏反应、硫化和酸化合成了用于镧/锕分离的4个萃取剂--二烷基二硫代次膦酸,其结构经NMR,IR和MS表征.     

2-乙基己基膦酸单(2-乙基己基)酯-H2SO4-钴(Ⅱ)、镍(Ⅱ)萃取体系中所形成的配合物研究

制备了一元酸性磷(膦)酸酯类萃取剂(HL)二(2-乙基已基)磷酸(P-204)和2-乙基已基膦酸单(2-乙基已基)酯(P-507)与钴(Ⅱ)、镍(Ⅱ)的配合物。通过元素分析、水含量测定、热重分析、红外和电子光谱及磁矩测定就二种萃取剂与钴、镍配合物的组成、性质和立体构型进行了比较研究。结果表明,二种配体所形成的配合物是相似的。深兰色的钴配合物CoL_2为四面体构型。棕色的镍的无水配合物NiL_2和绿色的含水配合物NiL_2·2H_2O对均为八面体构型。四面体钴配合物中键的共价性程度大于八面体的镍配合物。     

GC-MS检测Cyanex272萃取剂的研究

在钴镍萃取分离上,Cytec公司的Cyanex272表现优良,并在我国展开了工业应用[1].Cyanex 272是Cytec公司的产品,其87%的主成份为二(2,4,4-三甲基戊基)膦酸[2],分子式为C16H35PO2,分子量为290.这是起萃取作用的主要成份.Cyanex272中还有12%的另一固定组份为三(2,4,4-三甲基戊基)氧化膦,分子式为C24H51PO,分子量为386,无色液体,在水中溶解度为10 mg/L.     

钴(Ⅱ)-2-乙基己基膦酸单(2-乙基己基)酯固体萃合物成键特性和构型的研究

2-乙基己基膦酸单(2-乙基己基)酯(简写HEH(EHP)或P_(?07))是一种工艺性能优良的金属萃取剂,广泛应用于稀土分组及钴镍等金属的分离。对其萃取金属的性能和平衡的研究已有报道。研究萃合物的成键特性及空间构型,对于深入了解萃取机理有     

利用中空纤维膜器从铕中分离杂质锌

利用中空纤维膜器，采用逆流循环萃取法，用二（2，4，4-二甲基戊基）硫代膦酸（Cyanex302)从硫酸溶液中萃取分离锌和铕。探讨了膜萃取的反应机制，考察了料淮酸度、萃取剂浓度等因素对传质系数的影响，提出利用动力学竞争可以实现锌、铕混合组分的分离。研究了不同酸度、不同配比以及膜器串联的不同级数等条件对锌、铕混合物分离的影响。采用单级萃取时，只有锌被萃取，而铕不被萃取，且锌的萃取不完全；当采用膜器二级串联，经过100min后锌的萃取率达到94.92%，而铕的萃取率仅为8.59%；当采用膜器三级串联时，经过40min后，锌的萃取率达到99.9%以上，而铕的萃取率仅为6.53%。     

2-乙基己基膦酸单2-乙基己基酯与钕的萃合物在正己烷溶液中的结构研究

2-乙基己基膦酸单2-乙基己基酯[HEH(EHP)]是一种良好的萃取剂, 已被广泛地应用于稀土和钴和镍的分离[1,2]。对于它的萃取性能和机理已作过大量的研究。本文针对用HEH(EHP)萃取分离稀土时必须保证萃取剂与有机相稀土含量的摩尔比大于6, 否则即发生乳化现象, 利用蒸气压渗透法及红外光谱为手段, 研究了HEH(EHP)与钕所生成的萃合物在溶液中的存在形式及结构, 阐明发生乳化及破乳过程的实质。     

异烷基膦酸单烷基酯萃取分离稀土的研究

研究了异烷基膦酸单烷基酯系列萃取剂色层分离稀土的性能。结果表明,以八碳异烷基膦酸-1-甲基庚基酯分离稀土的性能最佳,体系酸度均较目前使用的萃取剂低,用1.73 mol/L HNO_3可将Tm、Yb、Lu完全分离,用它制成的负载树脂分离稀土,其柱效高,动力学性能好。另外,对萃取反应机理作了一些探讨。     

Extraction of neodymium(III) using binary mixture of Cyanex 272 and Cyanex 921/Cyanex 923 in kerosene

The extraction of Nd(III) using binary mixtures of Cyanex 272 (HA), Cyanex 921/Cyanex 923 (B) in kerosene from nitric acid medium has been investigated. The effect of aqueous phase acidity, extractant concentration, nitrate ion concentration and diluents on the extraction of Nd(III) has been studied. On the basis of slope analysis results, extracted species are proposed as Nd(NO₃)A₂·3HA and Nd(NO₃)₂·A·3HA·B using Cyanex 272 and its mixture with Cyanex 921/Cyanex 923, respectively. With the mixture of 0.1 M Cyanex 272 and 0.1 M Cyanex 923 in kerosene, the extraction of 0.001 M Nd(III) from 0.001 M HNO₃ solution was found to be 83.3 % whereas it was 73.3 % when 0.1 M Cyanex 921 used as synergist under same experimental conditions. The stripping data of Nd(III) from the loaded organic phase containing 0.1 M Cyanex 272 and 0.1 M Cyanex 921/Cyanex 923 with different acids indicated sulphuric acid to be the best stripping agent.     

Extraction of Polonium from Aqueous Lactic Acid Solutions Using Dioctyl Sulphide, Cyanex 272, Cyanex 301 or Cyanex 302 in Toluene

The extraction of polonium from lactic acid (HLac) solutions has been studied with di-n-octyl sulphide (DOS), Cyanex 272, Cyanex 301 and Cyanex 302 extractants dissolved in toluene. For the extraction with DOS, the extracted species is most likely PoO(Lac)₂·3DOS. The results for Cyanex 272 also indicate extraction via a solvation mechanism rather than cation exchange. The extracted species is probably PoO(Lac)₂·2HA. The major species extracted with Cyanex 301 or Cyanex 302 do not contain any lactate molecules. The extracted species is most likely PoOA₂ at low extractant concentrations, while at higher concentrations an adduct complex of the type PoOA₂·2HA is formed. The extraction of polonium increases in the order Cyanex 272 < Cyanex 302 < DOS < Cyanex 301, which is the same order as the increase of the number of sulphur atoms in the reagents.     

Solvent extraction of zinc from sulphate leaching solution of a sulphide-oxide sample using D2EHPA and Cyanex 272

Solvent extraction of zinc from sulphate leach solution obtained from the treatment of a sulphide-oxide sample, was investigated using D2EHPA and Cyanex 272 diluted in kerosene in a batch reactor. According to the results, D2EHPA exhibited the higher extraction efficiencies than Cyanex 272 at the organic/aqueous ratio of 1:1. The optimum concentration and pH for D2EHPA and Cyanex 272 were distinguished to be 0.5?mol/L and 2.5, and 0.035?mol/L and 3.5, respectively. Under these conditions, extraction efficiency was found to be ～75% for D2EHPA against 41% for Cyanex 272. The plot of log D versus log [D2EHPA] confirmed the presence of 1 mole D2EHPA in dimeric form for 1 mole Zn in the extraction system. Thermodynamic data showed that the zinc extraction process is endothermic. For D2EHPA, two-stage simulated counter-current extraction experiments were performed on the basis of the McCabe-Thiele diagram and the extraction percentage of zinc was found to be about 88%. The synergistic effect of Cyanex 272 and TBP with D2EHPA was particularly investigated. It was found that the mixture of 80% D2EHPA and 20% Cyanex 272 exhibited the best synergistic effect for Zn-extraction with a synergistic coefficient of 1.04.     

Determination of optimum process conditions for solvent extraction of thorium using Taguchi method

Solvent extraction of thorium was studied using Taguchi method. The effect of various parameters such as acid types (sulfuric, nitric, hydrochloric, sulfuric + nitric) and their concentrations from 0.001 to 4 M, initial thorium concentration (0.0001, 0.001, 0.01, 0.1 M) and solvent type (TBP, D₂EHPA, Cyanex921, Cyanex272) in the ranges of 0.001 to 1 M on thorium extraction efficiency were investigated. The maximum extraction of thorium was obtained while 0.001 M hydrochloric acid, 0.001 or 0.01 M thorium and Cyanex272 were used. Under these optimum conditions, the extraction percent and distribution coefficient of thorium were 98.7% and 73.8, respectively. Compared with the hydrochloric aqueous solution, the nitric acid system showed less variation in the extraction of thorium. The proposed process has been applied for the separation of Th(IV), U(VI), La(III), and Ce(III) from synthetic solution same as thorium ores (monazite).     

Synergistic extraction of uranium(VI) and thorium(IV) with mixtures of Cyanex272 and other organophosphorus ligands

The extraction of thorium(IV) and uranium(VI) from nitric acid solutions has been studied using mixtures of bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex272 or HA), and synergistic extractants (S) such as tri-butylphosphate (TBP), tri-octylphosphine oxide (TOPO) or bis(2,4,4-trimethylpentyl)thiophosphinic acid (Cyanex301). The results showed that these metallic ions are extracted into kerosene as Th(OH)₂(NO₃)A·HA and UO₂(NO₃)A·HA with Cyanex272 alone. In the presence of neutral organophosphorus ligands TBP and TOPO, they are found to be extracted as Th(OH)₂(NO₃)A·HA·S and UO₂(NO₃)A·HA·S. On the other hand, Th(IV), U(VI) are extracted as Th(OH)₂(NO₃)A·HA·2S and UO₂(NO₃)A·HA·S in the presence of Cyanex301. The addition of neutral extractants such as TOPO and TBP to the extraction system enhanced the extraction efficiency of both elements while Cyanex301 as an acidic extractant has improved the selectivity between uranium and thorium. The effect of TOPO on the extraction was higher than other extractants. The equilibrium constants of above species have been estimated by non-linear regression method. The extraction amounts were determined and the results were compared with those of TBP. Also, it was found that the binding to the neutral ligands by the thorium–Cyanex272 complexes follows the neutral ligand basicity sequence.     

Two-phase potentiometric metal extraction titrations of silver(I), copper(II) and cadmium(II) using some cation-exchangers as extractants

The use of two-phase potentiometric metal extraction titrations to study solvent extraction equilibria is described. The method provides a highly reproducible and convenient manner by which to determine extraction behaviour. The system was tested on a number of acidic extractants, namely D2EHPA, Ionquest 801, Cyanex 272, naphthenic acid and Versatic 10 acid. The extraction from an aqueous nitrate medium of silver(I), copper(II) and cadmium(II) was studied. The potentiometric data were used to obtain extraction curves and elucidate the nature of the extracted complexes by slope analysis and non-linear least squares treatment. In general, the following extraction order was obtained: D2EHPA > Ionquest 801 > Cyanex 272 and naphthenic > Versatic 10 for copper(II) and cadmium(II). Organophosphorus acids were shown to form complexes of the nature of Cu(HA(2))(2) with copper(II) and carboxylic acids formed dimeric complexes (CuA(2)(HA))(2). With cadmium octahedral complexes of the form CdA(2)(HA)(4) occurred. The extraction of silver(I) by Versatic 10 gave a dimeric complex (AgA(HA))(2). HA denotes the extractant in the acid form.     

Organophosphinic,phosphonic acids and their binary mixtures as extractants for molybdenum(VI) and uranium(VI) from aqueous HCl media

Extraction studies of uranium(VI) and molybdenum(VI) with organophosphoric, phosphinic acid and its thiosubstituted derivatives have been carried out from 0.1–1.0M HCl solutions. The extracted species are proposed to be UO₂R₂ and MoO₂ CIR on the basis of slope analysis for uranium(VI) and molybdenum(VI), respectively. The extraction efficiencies of PC-88A, Cyanex 272, Cyanex 301 and Cyanex 302 in the extraction of molybdenum(VI) and uranium(VI) are compared. Synergistic effects have been studied with binary mixtures of extractants. Separation of molybdenum(VI) from uranium(VI) is feasible by Cyanex 301 from 1M HCl, the separation factor log being 2.3.     

Liquid-liquid extraction of tetravalent zirconium from acidic chloride solutions using Cyanex 272.

The liquid-liquid extraction of zirconium(IV) from acidic chloride solutions was carried out with Cyanex 272 as an extractant diluted in kerosene. An increase of the acid concentration decreased the percentage extraction of metal, which indicates that the extraction follows ion exchange-type mechanism: MO2+(aq) + 2(HA)2(org) <--> MO (HA2)2(org) + 2H+(aq), where, M = Zr(IV); HA = Cyanex 272. The extraction of Zr(IV) increases with an increase of the extractant concentration. In a plot of log D vs. log[extractant], M is linear with a slope of approximately 2, indicating the association of two moles of extractant with the extracted metal species. On the other hand, the extraction decreases with an increase of the H+ ion concentration. A plot of log D vs. log[H+] gave a straight line with a negative slope of 1.7, indicating the exchange of two moles of hydrogen ions for every mole of Zr(IV). The effect of the Cl- ion concentration at a constant concentration of [H+] did not show any change in the D values. The addition of sodium salts enhanced the percentage extraction of metal, and followed the order of NaSCN > NaNO3 > Na2SO4 > NaCl. The stripping of metal from the loaded organic (L.O) with different acids indicated sulfuric acid to be the best stripping agent. An increase of the temperature during the extraction and stripping stages increases the metal transfer, showing that the process is exothermic. The synergism, regeneration and recycling capacity of Cyanex 272; the extraction behavior of associated elements, such as Hf(IV), Ti(IV), Al(III), Fe(III); and IR spectra of the extracted Zr-Cyanex 272 complex were studied.     

Extractive separation of Th(IV), U(VI), Ti(IV), La(III) and Fe(III) from Zarigan ore

In this study, the effects of various extraction parameters such as extractant types (Cyanex302, Cyanex272, TBP), acid type (nitric, sulfuric, hydrochloric) and their concentrations were studied on the thorium separation efficiency from uranium(VI), titanium(IV), lanthanum(III), iron(III) using Taguchi^??s method. Results showed that, all these variables had significant effects on the selective thorium separation. The optimum separations of thorium from uranium, titanium and iron were achieved by Cyanex302. The aqueous solutions of 0.01 and 1 M nitric acid were found as the best aqueous conditions for separating of thorium from titanium (or iron) and uranium, respectively. The combination of 0.01 M nitric acid and Cyanex272 were found that to be the optimum conditions for the selective separation of thorium from lanthanum. The results also showed that TBP could selectively extract all studied elements into organic phase leaving thorium behind in the aqueous phase. Detailed experiments showed that 0.5 M HNO₃ is the optimum acid concentration for separating of thorium from other elements with acidic extractants such as Cyanex272 and Cyanex302. The two-stage process containing TBP-Cyanex302 was proposed for separation thorium and uranium from Zarigan ore leachate.     

Extraction of Polonium from Aqueous α-Hydroxyisobutyric Acid Solutions Using Dioctyl Sulphide, Cyanex 272, Cyanex 301 or Cyanex 302 in Toluene

A study of the extraction of polonium from aqueous solutions containing -hydroxyisobutyric acid (-HIBA) was performed with four different extractants, di-n-octyl sulphide (DOS), Cyanex 272, Cyanex 301 and Cyanex 302, dissolved in toluene. The extracted complex for DOS at low -HIBA concentrations is most likely PoO(-HIB)₂·2DOS, while at higher -HIBA concentrations there seems to be a solvating effect implicating an extracted complex of the type PoO(-HIB)₂(-HIBA)₂·2DOS. For the extraction of polonium with Cyanex 272 the results are inconclusive. The extracted complex is either PoOA₂ or PoO(-HIB)₂·2HA. For extraction with Cyanex 301 or Cyanex 302 the major extracted species does not contain any -HIBA molecules. The neutral species in both cases is PoOA₂, extracted at low extractant concentrations, while at higher extractant concentrations a complex of the type PoOA₂·xHA is extracted. The extraction of polonium increases in the order Cyanex 272 < DOS < Cyanex 302 < Cyanex 301.