不同稀释剂中N_(1923)的界面性质

研究了伯胺 N192 3在不同稀释剂 /0 .1 mol/L(H,Na) NO3(p H=2 .3 4)体系中的界面性质 ,计算了界面吸附特性参数 cmin和 AI.N192 3在不同稀释剂体系中的界面活性顺序为 :正庚烷 >环己烷 >苯 >甲苯 >四氯化碳 >氯仿 >醋酸异戊酯 >甲基异丁基酮 (MIBK) .这一结果可能与稀释剂和萃取剂、稀释剂和有机相中增溶水及萃取剂和界面层水分子之间的相互作用有关 .对有关结果及其与萃取性能的关系做了分析和讨论     

HDEHP和HEHEHP界面性质及添加剂对界面性质的影响

测定了HDEHP、HEHEHP、TOPO、TBP、SDS和CTMAB的煤油溶液与硫酸盐水溶液所构成的液-液体系的界面张力,考察了水相pH对界面张力的影响,求得这些化合物的界面吸附常数,计算出饱和吸附时界面吸附分子的截面积,提出了用Cmin计算活性剂分配比的方法,研究了向HDEHP或HEHEHP体系中添加TOPO(或TBP)、SDS、CTMAB时界面张力的变化及其对萃取速率的影响。界面化学反应控制的萃取金属阳离子过程的速率将因添加剂占据界面和(或)形成界面负电层而降低,因添加剂与萃取剂形成界面活性较强的分子缔合物对金属的萃取而提高。     

TODGA/HNO_3萃取La~(3+)的界面性质

利用滴体积法研究了La~(3+)/HNO_3/N,N,N',N'-四辛基-3-氧戊二酰胺(TODGA)/稀释剂体系的界面性质,考察了TODGA浓度、液滴形成时间、稀释剂种类、La~(3+)浓度、体系温度、离子强度和溶液酸度等因素对体系界面性质的影响.实验结果表明,体系达到界面饱和吸附时间约为120 s,可认为体系达到萃取平衡;TODGA浓度不同时,界面张力也不同,进而判定界面饱和吸附物种亦不相同;极性较小的稀释剂体系的界面张力降低较大,按照正辛烷环己烷苯甲苯次序降低;HNO_3对TODGA的质子化作用使其表面活性显著增强,故硝酸浓度增大导致界面张力降低;Na NO_3的存在降低了界面上游离萃取剂分子的浓度,致使界面张力增大.     

酸性磷类萃取剂在硫酸介质中对Y(Ⅲ)的协萃机制研究

对HDEHP(H2A2),HEH/EHP(H2B2),Cyanex272(H2L2)萃取剂在硫酸介质中单独以及HDEHP-HEH/EHP和HDEHP-Cyanex272混合萃取剂萃取稀土元素Y(Ⅲ)的机制进行了研究. 研究发现,单独采用HDEHP和HEH/EHP萃取Y(Ⅲ)时,SO2-4参与了反应,造成反应过程中放出的H 个数随萃取剂浓度的变化而变化,对于单独采用Cyanex272萃取Y(Ⅲ)的过程中则是OH-参与了反应. 计算了混合萃取剂萃取Y(Ⅲ)的协萃系数(R),当水相平衡pH=1.2时,HDEHP和HEH/EHP混合萃取体系与HDEHP和Cyanex272混合萃取体系萃取Y(Ⅲ)的R分别为27.68和48.99,并且协萃系数随水相平衡pH的升高而增加. 确定了在HDEHP和HEH/EHP混合萃取体系中的协萃反应并计算了反应的平衡常数及萃合物形成反应的稳定常数,反应机制为阳离子交换反应.     

表面活性剂对HDEHP萃取动力学的影响

用上升液滴法测定二(2-乙基己基)磷酸(HDEHP)从硫酸盐介质中萃取Co^2^+的速率。研究体系中加入不同表面活性剂所引起萃取速率的不同改变: 三辛基氧化膦(TOPO)因与HDEHP形成可萃取的Co^2^+活性分子缔合物, 降低了萃取过程活化能而使反应加速; 十二烷基磺酸钠(SDS)和十六烷基三甲基溴化铵(CTMAB)因占据发生萃取反应的界面区, 减小了HDEHP与Co^2^+反应的机会而使反应减速; SDS还因其在界面形成较强的负电场(层), 造成Co^2^+的附加势能而使萃取速率有更大幅度的降低。     

萃取剂HDEHP在不同稀释剂中的聚合性质

HDEHP在惰性稀释剂中由于分子间氢键作用易形成二聚体[1 ] ,其二聚常数已有报道[2 ] ,但很不一致。由于萃取动力学、液—液界面性质都与萃取剂在有机相中的存在状态密切相关 ,本文研究了不同稀释剂中 HDEHP的聚合性质 ,并实现了二聚常数与稀释剂物理常数间的定量关联。实　验　部　分一 .试剂和仪器HDEHP,工业品 ,经提纯纯度大于 99% ;氯仿、苯、甲苯、环己烷、四氯化碳、甲基异丁基酮 ,均为分析纯 ;正辛烷 ,化学纯。TOA p H计 ,日本岛津 ;KS恒温振荡器 ,山东大学化学院金工室改装 ;FTS 16 5红外光谱仪 ,美国 Bio- Rad公司。二 .…     

液-液萃取体系界面特性的研究——Ⅱ.HEH(EHP)在水和不同稀释剂体系中的界面性质

通过对界面吸附特性参数的测定,推断HEH(EHP)以单分子状态吸附于液-液界面。吸附能力的强弱与稀释剂性质及温度有关。两液相极性差别越大,界面吸附能力越强。温度越高,吸附能力越弱。本文还讨论了HEH(EHP)的界面吸附与其萃取性能、相间分配等关系。     

2-乙基己基膦酸单2-乙基己基酯和二(2-乙基己基)磷酸从硫酸介质中协同萃取Ce(Ⅳ)的研究

研究了用2-乙基己基膦酸单-2-乙基己基酯(HEH/EHP,P507)和二(2-乙基己基)磷酸(HDEHP,P204)从硫酸介质中协同萃取Ce(Ⅳ)的机制.结果表明:在HEH/EHP的摩尔分散在0.6时,体系的协萃系数最大.Ce(Ⅳ)以Ce(SO4)0.5HL2A2的形式被萃人有机相,协萃反应为阳离子交换机制.同时还得到了HEH/EHP和HDEHP从硫酸介质中协同萃取Ce(Ⅳ)时,体系的平衡常数及热力学函数如△G,△H和△S等.     

磷酸体系中微量稀土元素萃取动力学研究

采用新型恒界面池法进行了磷酸体系中用P204萃取La(Ⅲ),Sm(Ⅲ)和Y(Ⅲ)的动力学研究,考察了搅拌速度、温度、比界面积、磷酸浓度及萃取剂浓度等因素对萃取速率的影响.结果表明:磷酸体系中用P204萃取La(Ⅲ),Sm(Ⅲ)和Y(Ⅲ)的表观活化能E_a分别为27.0,22.2和21.1 kJ·mol~(-1),在体相P204浓度大于在液一液界面饱和吸附时的最低浓度C_(min)时,其在界面已达到吸附饱和,反应的主通道由界面变为体相,在该体系下P204萃取La(Ⅲ),Sm(Ⅲ)和Y(Ⅲ)反应为体相化学反应和扩散反应混合控制.     

酰胺荚醚类萃取剂结构对Gd(Ⅲ)萃取性能的影响

本文合成了4种新型不对称酰胺荚醚萃取剂:N,N′-二甲基-N,N′-二苯基-3-氧戊二酰胺(DMDPhDGA)、N,N′-二甲基-N,N′-二己基-3-氧戊二酰胺(DMDHDGA)、N,N′-二甲基-N,N′-二辛基-3-氧戊二酰胺(DMDODGA)、N,N′-二甲基-N,N′-二癸基-3-氧戊二酰胺(DMDDDGA)。以氯仿为稀释剂,研究了N,N,N′,N′-四丁基-3-氧戊二酰胺(TBDGA)及上述4种萃取剂从硝酸体系中萃取Gd(Ⅲ)的反应机理,得出萃取能力顺序为:DMDHDGA>DMDDDGA>DMDODGA>DMDPhDGA>TBDGA。考察了水相酸度和萃取剂浓度对萃取分配比的影响,得出萃合物中有3个萃取剂分子同时参与配位;并结合红外光谱解释了萃取剂结构与萃取性能的关系。     

Gelation in Extraction Systems with Basic Copper(II) and Neodymium(III) Alkyl Phosphates

Gelation in extraction systems containing purified or commercial di(2-ethylhexyl) hydrogen phosphate (HDEHP), copper(II) or neodymium(III) hydroxides, hydrocarbon solvent, and water was studied at different ratios of the metal and extractant. The region was determined in which gelation caused by formation of basic neodymium(III) di(2-ethylhexyl) phosphates occurs in decane. Some characteristics of organogels in the HDEHP (commercial)-Cu(OH)₂-organic diluent (decane, hexane or toluene)-H₂O extraction systems were studied.     

Adsorption at the liquid/liquid interface in mixed systems with hydrophobic extractants and modifiers 1. Study of equilibrium interfacial tension at the hydrocarbon/water interface in binary mixed systems

Equilibrium interfacial tension at the liquid/liquid interfaces for two chelating metal ion extractants, 2-hydroxy-5-nonylacetophenone oxime (HNAF) and 1-phenyldecane-1,3-dion (beta-diketone), two solvating extractants, trioctylphosphine oxide (TOPO) and tributyl phosphate (TBP), and a modifier, decanol, were obtained with a drop volume tensiometer. Moreover, four equimolar binary mixtures of extractant/extractant and extractant/modifier type were considered. The composition of the mixed adsorbed monolayer and the molecular interaction parameters beta were determined by the Rosen equation. It was found that in all the studied systems coadsorption exists; however, synergism in the reduction of interfacial tension was not observed. The obtained results indicate that in the case of three mixtures considered the composition of a mixed monolayer at the hydrocarbon/water interface was quite different from that in the bulk organic phase. Only for the TOPO/beta-diketone mixture were the compositions at the interface and in the bulk organic phase similar. The obtained results indicate that it is impossible to predict the composition of a mixed monolayer by taking into account the interfacial activity of individual components of the mixture. In some cases the compound shows lower interfacial activity (smaller efficiency and effectiveness of adsorption) and occupies a dominant position at the interface, regardless of the type of hydrocarbon used as the organic diluent.     

A method for the synthesis of spherical copper nanoparticles in the organic phase

In this paper, stable metallic copper nanoparticles protected by bis(ethylhexyl)hydrogen phosphate (HDEHP) were prepared in the organic phase. In the synthesis of copper nanoparticles, the bis(ethylhexyl)hydrogen phosphate (HDEHP) acted as both a phase-transfer agent and a particle protector. It was also found that the protective ability of HDEHP was different with different diluent polarities. Despite zero valent Cu initially forming in all the solvents studied, it has been found that the zero valent Cu can easily transform into oxides in those solvents with high dipole moments under ambient conditions. Only in those nonpolar solvents, the metallic copper nanoparticles are stable in air. In addition, theoretical analyses were made in order to interpret the interaction mode between the copper nanoparticles and the surfactant HDEHP.     

HDEHP和HEHEHP萃取Au(Ⅰ)的研究

在298±1K时以恒界面搅拌池法考察了Au(I)/(Na,H)Cl、CS(NH₂)₂/HDEHP(或HEHEHP)-煤油体系的萃取平衡和动力学过程.确定了萃取平衡机理为阳离子的交换,动力学过程的速控步骤可能发生在两相交界处,属于界面反应。     

Purity Considerations and Interfacial Behavior of Solvent Extraction Systems

Abstract

The techniques to purify different components of a typical solvent extraction system, viz., n-hexane/di(2-ethylhexyl)phosphoric acid (HDEHP)/CaCl₂ solution, are described. Data showing how the purity of the different components affects the interfacial tension (γ) are given. The interfacial behavior of the n-hexane/ HDEHP/0.01 mol dm^?3 CaCl₂ solution system was studied as a function of HDEHP concentration and aqueous phase pH. γ-log [HDEHP] curves were also determined at pH 4 when the aqueous phase contained 0.05 mol dm^?3 MgCl₂, CaCl₂, SrCl₂ or BaCl₂. γ-log [HDEHP] curves revealed interaction of the metal ions with the extractant and exhibited a behavior reminiscent of aggregate formation when the aqueous phase contained Ca²⁺.     

Investigation of aggregation in solvent extraction of lanthanides by acidic extractants (organo-phosphorus and naphthenic acid)

Three acidic extractants (Ⅰ) di(2-ethylhexyl) phosphoric acid (HDEHP),(Ⅱ) 2-ethylhexyl phos-phonic acid mono-2-ethylhexyl ester (KEHPEHE) and (Ⅲ) naphthenic acid were employed in preparing the samples for the characterization of the coordination structure of lanthanlde-extractant complexes and the physicochemical nature of aggregates formed in the organic diluent of the solvent extraction systems.Photo correlation spectroscopy (PCS) re-suits on the aggregates formed by the partially saponified HDEHP in n -heptane showed that the hydrodynamic radius of the aggregates was comparable to the molecular dimensions of HDEHP.The addition of 2-octanol into the diluent,by which the mixed solvent was formed,increased the dimensions of the corresponding aggregates.Aggregates formed from the ianthamde ions and HDEHP in the organic phase of the extraction systems were found very unstable.In the case of naphthenic acid,PCS data showed the formation of w/o microemulsion from the saponified naphthenic acid in the mix     

The extraction of beryllium(II) by di-(2-ethyl hexyl)-phosphoric acid from sulphate media

The distribution of Be(II) between aqueous sulphuric acid solutions and organic phases of di-(2-ethyl hexyl)-phosphoric acid (HDEHP) has been described. The dependence of extraction on contact time, acidity, metal and extractant concentration, diluent type and temperature was thoroughly investigated. The possible mechanism of the extraction is discussed on the basis of results obtained.     

二-(2-乙基己基)磷酸从盐酸介质中萃取铀(Ⅳ)的动力学研究

采用上升单液滴法研完了二-(2-乙基己基)磷酸-环己烷从盐酸介质中萃取铀(Ⅳ)的动力学。测定了不同萃取条件对萃取速率的影响,提出了速率方程,并对萃取反应机理进行了讨论。     

Activity Coefficients of di-(2-ethylhexyl) Phosphoric Acid in Select Diluents

This work characterizes the non-ideal behavior of the solvent extraction agent di-(2-ethylhexyl) phosphoric acid (HDEHP), constituting one piece of an effort to develop increasingly accurate models of advanced fuel separation processes such as TALSPEAK. Robust models are particularly important for processing high-level radioactive material in order to minimize the generation of secondary waste and to ensure reliable process control. Here, vapor pressure osmometry (VPO) data on binary solutions of HDEHP in toluene, dodecane, or cyclooctane yields the activity coefficients for each component after analysis. Initially, diluent activity data is obtained using the VPO results and then modeled using Scatchard-Hildebrand theory to provide the activity coefficients for HDEHP.