D_2EHPA-HCl-HAc体系萃取Pr(Ⅲ)的机制分析与萃取平衡常数

在pH1条件下,采用EDTA容量滴定法测定D2EHPA-HCl-HAc体系萃取Pr(Ⅲ)过程两相中的Pr浓度分别考察溶液酸度和萃取剂浓度对Pr的分配比的影响,通过对D2EHPA以及D2EHPA-HCl-HAc体系负载Pr有机相进行红外光谱测试。分析探究了D2EHPA-HCl-HAc体系萃取Pr的机制,并确定萃取平衡常数。研究结果表明,当pH1时,萃取过程的实质是Pr离子与基团P-OH发生置换,遵循阳离子交换机制,以及与基团P=O发生的络合配位作用,其萃取平衡常数KPr为1×100.13。     

P204-HCl-HAc体系萃取La的机理分析与萃取平衡常数

在pH1条件下,采用EDTA容量滴定法测定P204-HCl-HAc体系萃取La(Ⅲ)过程两相中的La浓度,并分别考察溶液酸度和萃取剂浓度对La分配比的影响;通过对P204以及P204-HCl-HAc体系负载La有机相进行红外光谱测试分析,探究P204-HCl-HAc体系萃取La的机理,并确定其萃取平衡常数。研究结果表明,当pH1时,萃取过程实质是La离子与基团P-OH遵循阳离子交换机制发生置换,以及与基团P=O发生络合配位作用,其萃取平衡常数KLa为10-0.02。     

石油亚砜萃取钯(Ⅱ)性能和机理研究

研究了ＨＮＯ３中中性萃取剂石油亚砜萃取钯（Ⅱ）的性能。通过考察萃取剂浓度、溶液酸度和温度对钯（Ⅱ）萃取平衡的影响,确定了萃取机理,求得了萃取反应平衡常数和有关热力学参数;验证了萃取体系对钯（Ⅱ）的萃取动力学过程为一级反应。     

D2EHPA萃取分离Zn(Ⅱ),Cd(Ⅱ)的研究

采用二-(2-乙基己基)磷酸(简称D2EHPA)作为萃取剂,以磺化煤油为稀释剂,研究了硫酸盐溶液体系中萃取分离Zn(Ⅱ),Cd(Ⅱ)的性能,考察了萃取时间、pH、萃取剂浓度、水相锌镉离子浓度、温度等因素对锌、镉萃取分离过程的影响.实验结果表明,D2EHPA/煤油体系对锌萃取分离效果良好.     

石油亚砜萃取钯的热力学和动力学研究

本文研究了用石油亚砜(PSO)的氯仿溶液从硝酸介质中萃取钯(Ⅱ)的热力学和动力学过程。考察了萃取剂浓度和温度对钯萃取的影响,测得萃取反应的平衡常数K和热力学参数ΔH、ΔG及ΔS;进一步验证了体系对钯(Ⅱ)是一级反应,从实验结果推论出萃取过程为界面化学反应控制型机理。其反应过程可表示为:     

D_2EHDTPA萃取铟的热力学研究

报道了用二 (2 乙基己基 )二硫代磷酸为萃取剂 ,以正庚烷为稀释剂萃取铟的热力学研究。在In2 (SO4 ) 3+Na2 SO4 +D2 EHDTPA +n C7H1 6 +H2 O体系中 ,在温度 2 78.15～ 3 0 3 .15K和离子强度 0 .1～ 2 .0mol·kg- 1 范围内 ,以Na2 SO4 为支持电解质 ,测定了萃取平衡水相中In3+浓度和pH值。计算了萃取反应的标准平衡常数K0 ,并得到经验公式logK0 =43 .93 -5 3 68.5 4 T -0 .0 699T ,同时计算了萃取反应的其他热力学量 ,并指出了焓和熵都是此萃取过程的推动力     

N,N‘—二辛基甘氨酸萃取钯热力学研究

本文研究了 N ,N '-二辛基甘氨酸 ( DOG)从盐酸体系中萃取钯的热力学。通过考察 DOG浓度对 Pd( )萃取的影响 ,测出了萃取反应的表观平衡常数 K、焓变Δ H、自由能ΔG和熵变Δ S。     

对高镁卤水萃取锂的性能及热力学函数的研究

分别研究了ＳＫ－ＳＥ体系对锂的萃取性能及萃取的温度效应。根据ｌｇＤＬｉ与Ｔ＾－１的线性函数关系，计算了萃取过程的焓变ΔＨ；由表现萃取平衡常数Ｋｅｘ和ΔＨ求得萃取自由能ΔＧ和熵变ΔＳ，表明对锂的萃取反应是放热反应，萃取过程为熵减过程。     

二(2-乙基己基)磷酸对钼(Ⅵ)的萃取

研究了25%二(2-乙基己基)磷酸(D2EHPA)的正十二烷溶液在HNO3体系中对Mo(Ⅵ)的萃取。实验结果表明,温度对Mo(Ⅵ)的萃取分配比有较大的影响,萃取过程中有明显的热效应。在HNO3浓度为3mol/L时,Mo(Ⅵ)以MoO22+形式被萃取,MoO2(NO3)2与D2EHPA形成1∶2的配合物,并给出萃取平衡方程式。     

非理想条件下P507对硝酸溶液中钇和铕萃取平衡的分析模拟

在非理想条件下,研究了溶剂Shellsol D70 中2-乙基己基膦酸单(2-乙基己基)酯(P507)对硝酸溶液中钇和铕的萃取平衡,建立了平衡分配比的化学基模型.同时研究了萃取剂P507在硝酸盐溶液和稀释剂之间的分配平衡.结果表明,P507的水相溶解度很低,在有机相中大部分以二聚体形式存在;在低酸度区稀土的萃取主要按阳离子交换反应进行,在高酸度区溶剂化反应则变得明显.此外,模型还包括稀土和NO3-的络合反应、P507对HNO3的竞争萃取以及(HR)2非理想性的修正.采用非线性最小二乘法确定了萃取平衡常数.对于稀土单元体系,在初始浓度较宽范围内(稀土浓度最高至0.1mol/L,硝酸0.05mol/L～3mol/L及萃取剂0.25mol/L～1mol/L),模型能以良好精度预测实验数据;也证实了它对稀土二元体系萃取平衡预测的适用性.     

复杂镍浸出液萃取净化的研究

以D2EHPA为萃取剂,从钼镍矿的复杂镍浸出液中萃取分离锌、铜。考察了萃取平衡时间、D2EHPA体积浓度、相比(O/A)、料液pH对萃取分离锌、铜效果的影响,确定了D2EHPA萃取锌、铜的最佳条件。室温下萃取除杂的最佳工艺条件为:萃取平衡时间3 min,D2EHPA的体积浓度20%,相比1∶1,料液pH=2.0,一级萃取率锌为89.5%,铜为11.0%。负载有机相经1 mol/L的H2SO4反萃,锌、铜和镍均可完全反萃。经三级逆流萃取可将料液中锌降低到0.01 g/L,萃取率达98.9%。     

Extraction mechanism of copper by versatic 10

The extraction mechanism of copper from an aqueous ammonia-ammonium nitrate mixture by an n-hexane solution of Versatic 10 was studied from the standpoints of the equilibrium distribution of copper between aqueous and organic phases, the aqueous solubility and interfacial adsorption equilibrium of Versatic 10 and the extraction rate of copper.The equilibrium relations of the distribution of copper and the aqueous solubility and the interfacial adsorption of Versatic 10 were interpreted quantitatively and these equilibrium constants were evaluated.The extraction rate of copper was found to be proportional to the copper concentration in the aqueous phase, inversely proportional to the hydrogen ion concentration and independent of the Versatic 10 concentration in the organic phase. From the experimental results of the extraction rate and the interfacial adsorption equilibrium, it was inferred that the extraction rate was controlled by the elementary reaction between the copper ion in the aqueous phase and the anionic species of Versatic 10 adsorbed at the interface.     

Chemically based model to predict distribution coefficients in the Cu-LIX 65N and Cu-KELEX 100 systems

A chemically based thermodynamic model to predict the distribution coefficients have been developed for the Cu-LIX 65N and Cu-KELEX 100 systems. The predictive model makes use of the aqueous phase cupric sulfate complex stoichiometric stability constant expressed as its degree of formation, their extraction mechanism, and the equilibrium constant for the extraction reaction. The distribution coefficient of copper can be predicted by the equation K_d = k₁α_o ², where is the ratio of the equilibrated organic concentration to the equilibrated hydrogen ion concentration in the aqueous phase, k₁ is the effective equilibrium constant containing the quotient of the activity coefficients of the reacting species and α_o is the degree of formation of the free cupric ion in the equilibrated aqueous phase. Excellent agreement between the experimental data and the predicted values was obtained. Formerly Graduate Fellow, Iowa State University     

Extraction equilibria in the system GaCl3-AlCl3-HCl-H2O-tributyl phosphate

Partition equilibria and solution chemistry of the system GaCl₃-AlCl₃-HCl-H₂O-tributyl phosphate is characterized by a simultaneous extraction of gallium chloride, hydrochloric acid, and water by a solvating mechanism. The salting-out power of the aqueous phase was explained by taking into account the stability of aluminum chloride and gallium chloride complex species and the calculated concentration of free chloride ions actually available for the extraction of gallium. Three gallium extraction mechanisms in the range of compositions studied are the extraction of GaCl₃ at low H⁺ and salt concentrations, the extraction of GaCl^- ₄ at moderate H⁺ and salt concentrations, and the competition between the extraction of GaCL^-4 and an HC1-TBP complex at high H+ and salt concentrations. The extraction of gallium over a wide range of distribution ratios (D = 1 to 1 x 10⁴) could be represented by a chemically based model taking into account the free chloride concentration and the activity coefficient of the total chloride ions. Formerly Visiting Scientist, Ames Laboratory, USDOE     

Synergistic extraction of iron(III) at higher concentrations in D2EHPA-TBP mixed solvent systems

The extraction of iron(III) from chloride solutions at macrolevel concentration by different solvents such as tri-n-butyl phosphate (TBP), di(2-ethylhexyl) phosphoric acid (D2EHPA), and their mixture in various proportions has been investigated at different acid concentrations. The synergistic extraction of iron(III) with a mixture of TBP and D2EHPA was studied and the results were compared with that of the extraction by individual solvent alone. An increase in the concentration of the synergist, TBP, in the D2EHPA-TBP solvent system resulted in an increase in the synergistic co-efficient value. The experimental data are treated graphically to explain the formation of organic phase extracted species, and the equilibrium extraction constants for the species are determined. It is found that a maximum of two molecules of TBP are adducted to the extracted species of the corresponding nonsynergistic system. Stripping of iron(III) with hydrochloric acid from loaded D2EHPA was found to increase with an increase in acid concentration. In the case of D2EHPA-TBP mixtures, stripping efficiency was increased with an increase in acid concentration up to a certain level and then it was decreased. The experimental results indicate that an iron exchange reaction between loaded D2EHPA and TBP proceeds during stripping at a higher concentration of hydrochloric acid (from mixed loaded solvent system). A plausible mechanism for iron(III) extraction and stripping has been discussed.     

A novel method for synthesis of styryl phosphonate monoester and its application in La(III) extraction

Herein, styryl phosphonate monoester (SPE) was synthesized and first introduced as rare earth extractant. The solvent extraction of lanthanum (III) from nitrate solution using styryl phosphonate mono-iso-octyl ester (SPE108), di-2-ethylhexyl phosphoric acid (D2EHPA) and 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (EHEHPA) as extractants was investigated. The effects of experimental parameters including equilibrium time, extractant concentration, aqueous pH, phase ratio and salt concentration on the extraction process were studied. The results indicate that the extraction ability and capacity of the extractants follow the order: SPE108 > D2EHPA > EHEHPA. What's more, the extraction process is less affected by ammonium sulfate in the aqueous phase with SPE108. The results of the separation between lanthanum and adjacent lanthanides (Ce, Pr, Nd, Sm) show that SPE108 can separate lanthanides efficiently at low pH. The extraction mechanism of SPE108 is proved to be similar to D2EHPA, and the density functional theory (DFT) calculation results infer that SPE108 exhibits superior extraction ability due to its strong electron-accepting ability.     

Extraction equilibrium conditions of beryllium and aluminium from a beryl ore for optimal industrial beryllium compound production

This study examines the extraction of beryllium and aluminium from a Nigerian beryl ore using Cyanex®272 in kerosene from an aqueous sulphate pregnant solution. Parameters such as extractant concentration and equilibrium pH that dictates the extraction yield were studied. Under the following conditions: temperature 27?±?2°C, phase ratio 1?1, about 45.50 and 46.76% of beryllium and aluminium were extracted by 0.15?mol?L^?1 Cyanex®272 concentration within 30?min. However, the extraction yield of beryllium and aluminium was increased to 91.68% and 97.89% at equilibrium pH of 3 and 4, respectively, for beryllium and aluminium at 27?±?2°C. A 0.05?mol?L^?1 H₂SO₄ solution was found to be adequate for the stripping of about 99.00% Be and 95.40% Al from the loaded organic phase. The pure solutions containing metal ions were accordingly beneficiated to obtain beryllium and aluminium compounds of industrial values.     

Chemically based model to predict distribution coefficients in the Cu-LIX 65N and Cu-KELEX 100 systems

A chemically based thermodynamic model to predict the distribution coefficients have been developed for the Cu-LIX 65N and Cu-KELEX 100 systems. The predictive model makes use of the aqueous phase cupric sulfate complex stoichiometric stability constant expressed as its degree of formation, their extraction mechanism, and the equilibrium constant for the extraction reaction. The distribution coefficient of copper can be predicted by the equationK _d =κ₁α₀ϕ², where ϕ is the ratio of the equilibrated organic concentration to the equilibrated hydrogen ion concentration in the aqueous phase,k ₁ is the effective equilibrium constant containing the quotient of the activity coefficients of the reacting species and α₀ is the degree of formation of the free cupric ion in the equilibrated aqueous phase. Excellent agreement between the experimental data and the predicted values was obtained.     

修饰聚合物盐水液-固萃取体系分离钪(Ⅲ)和镨(Ⅲ)的研究

究了Sc和Pr在聚乙二醇 亚氨基二乙酸 (简称PEG IDA)混合Tween 80 盐 水液 固萃取体系中的分配行为 ,讨论了修饰物用量、萃取酸度、吐温用量及分相盐种类和浓度对其萃取率的影响 ,筛选出最佳萃取分离条件 ,控制萃取酸度 ,实现了Sc和Pr的分离。并用pH电位法在 3 0℃的 0 .1mol·L- 1 KNO3溶液中测定了PEG IDA的离解常数以及PEG IDA与Sc和Pr形成的配合物的稳定常数 ,研究了稳定常数与稀土在PEG IDA修饰聚合物 盐 水液 固亲和萃取体系中分配行为的关系 ,并据此对该体系富集分离稀土的机制进行了初步探讨。结果表明 :Sc和Pr是通过与PEG IDA形成配合物而被萃入固相的。     

P204萃取铒的热力学和动力学研究

用含萃取剂P204的磺化煤油对稀土离子Er~（3+）进行萃取平衡研究,得到了萃取平衡式和平衡常数。用恒界面槽测量稀土离子的萃取速率和反萃速率,考察了Er~（3+）浓度、H~+浓度、P204液度和络合物浓度对反应速率的影响,从而得到了反应速率的表达式。提出了界面反模型,用动力学及界面张力实验进行了验证。