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。     

二(2-乙基己基)磷酸萃取L-精氨酸

二(乙基己基)磷酸;二(2-乙基己基)磷酸萃取L-精氨酸     

二(2-乙基己基)磷酸萃取亮氨酸平衡研究

萃取平衡;二乙基己基磷酸;二(2-乙基己基)磷酸萃取亮氨酸平衡研究     

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.     

2-乙基己基膦酸单(2-乙基己基)酯对两价金属离子的萃取平衡

本文报导用2-乙基己基膦酸单(2-乙基己基)酯在煤油溶剂中萃取Sn(II),Pb(II), Zn(II)和Cd(II)等的平衡, 应用斜率法研究了萃取平衡; 合成了与Zn(II)和Pb(II)固体萃合物, 在元素分析和有关离子分析的基础上结合最小二乘法线性回归探讨了萃取机理及有关萃合物组成; 考察了在加入三辛基氧化膦(TOPO)时, 2,乙基己基膦酸单(2-乙基己基)酯对金属离子萃取性能的影响.     

两相滴定法研究2-乙基己基膦酸单2-乙基己基酯从盐酸介质中萃取钕(Ⅲ)的动力学

本文利用两相滴定法作为分析手段,用恒界面池搅拌法考察了多种因素对2-乙基己基膦酸单2-乙基己基酯(HEHEHP,HA)从盐酸介质中萃取Nd(Ⅲ)动力学的影响,从实验结果推论出萃取过程为界面化学反应控制型机理。     

2-乙基己基膦酸2-乙基己基酯钠皂微乳液

HA( 2-乙基己基膦酸 2-乙基己基酯 )是一种性能优良的萃取剂,经皂化形成微乳液后,能大大提高萃取率 .许多学者对含有中长链醇等助表面活性剂的 HA碱皂微乳液的物理化学性质进行了深入的研究 [1－ 4].　　本文报导了用 NaOH皂化不含任何助表面活性剂的 HA煤油溶液,当体系中的 NaOH与 HA数量比达到一定值时,会形成稳定的 W/O型微乳液 .不同的 nNaOH:nHA形成的微乳液的状态可能有所不同 .对这种不含助表面活性剂的微乳液的相行为、电导、溶水量等物理化学性质进行了初步研究 .1实验部分 （ 1） 仪器和试剂 DDS-11A型电导率仪,上…     

2—乙基己基膦酸单2—乙基己基酯与钴,镍,铜,锌固体萃合物的研究

酸性磷(瞵)酸酯是一类重要的萃取剂,它们对金属离子的萃取性能和机理研究巳有报导,但大多限于溶液体系。酸性磷酸酯金属萃合物的研究也有报导,但对固态烷基膦酸单烷基酯金属萃合物方面的报导较少。本文报导2-乙基已基膦酸2-乙基已基酯(简称HEH(EH)P或HA)金属(M=Co、Ni、Cu、Zn)固体萃合物的磁性,电子光谱和红外光谱,结合热分析结果对萃合物的成键特性和可能构型进行了讨论。     

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

用蒸气压渗透法和红外光谱法测定了2-乙基己基膦酸单2-乙基己基酯[HEH(EHP),以下简称 HA]与钕的萃合物在含有不同浓度的 HA-正己烷溶液中的平均聚合度.NdA_3在37℃下的正己烷中溶解度约为1.2×10~(-2)mol·dm~(-3),此时 NdA_3的平均聚合度为7,(?)取桥式与钕配位.向该溶液中不断加入 HA 时,生成 NdA_3·nHA(n=1,2,3),部分桥式配位被单齿配位的(?)所取代,同时平均聚合度下降,当~C(HA)/~CNdA_3≥3时,平均聚合度下降为1,桥式配位的膦氧桥大部分被单齿配位的膦氧根所代替.在所有情况下钕的配位数均为6.     

2-乙基己基膦酸单(2-乙基己基)酯萃取稀土元素机理的研究 III.高浓度稀土元素(III)在H~+(HNO_3,HCl)-H_2O-HEH(EHP)-煤油体系中的分配及萃取反应

2-乙基己基膦酸单(2-乙基己基)酯[HEH(EHP),HL]是萃取分离稀土元素的有效萃取剂.作者及马恩新等研究了HEH(EHP)萃取低浓度稀土元素的平衡反应.Lenz等认为二(2-乙基己基)磷酸(HDEHP)萃取高浓度Nd(Ⅲ)和Sm(Ⅲ)时,ClO_4~-及NO_3~-参与萃取反应.定量研究HEH(EHP)从矿物酸溶液中萃取高浓度稀土元素(Ⅲ)的平衡规律及萃取反应具有实际意义,有关这方面的研究尚未见报道. 本文结合分离工艺,系统地研究了高浓度稀土元素在H~+(HNO_3,HCl)-H_2O-1.50FHEH(EHP)-煤油体系中的分配平衡,通过IR、NMR及平衡有机相中NO_3~-和Cl~-浓度的定量测定,提出了低酸度下不同稀土浓度的萃取反应.     

2-乙基己基膦酸单2-乙基己基酯萃淋树脂的物理性能与分离性能的关系

1　引　　言萃取色谱法对于高纯稀土的分离具有其它方法无可比拟的独特优点 ,但该法仍存在负载量低、萃取剂利用率较低等不足。要克服这些不足 ,一是使用高选择的萃取剂作固定相 ,已证明 2 乙基己基膦酸单 2 乙基己基酯 (即Ｐ5 0 7)萃取剂是目前性能最好 ;二是提高柱效率 ,可通过改善色谱操作技术及色谱柱型式的设计或改善树脂物理结构来实现。而从树脂物理结构的角度提高柱效率的报道很少。本实验室原先对Ｐ5 0 7萃淋树脂的孔结构已做过一些研究 ,表明适宜的孔结构有利于萃取剂分布均匀 ,可提高萃取剂的利用率和分离性能 ,但树脂制备和分…     

Thermochemical behaviour of lanthanum complexes of 2-ethylhexyl phosphoric acid

The thermochemical behaviour of solid-state complexes of lanthanum with mono-(2-ethylhexyl) phosphoric acid (H₂B) (La(HB)₃·1.5H₂O and La₂B₃·3H₂O) was studied. The thermal decomposition of these complexes proceeds without melting to yield La(PO₃)₃ and a mixture of La(PO₃)₃ and LaPO₄, respectively. La(HB)₃1.5H₂O decomposes via dehydration (323–383 K), condensation of the OH-groups with formation of a diphosphate structure (383–458 K) and a stepwise degradation of the hydrocarbon chains (443–565 K). The dehydration of La₂B₃·3H₂O (333–433 K) is followed by decomposition of the hydrocarbon group. From a combination of the present results with previous data [1], it was concluded that the temperatures and mechanisms of the decomposition of the hydrocarbon part of the lanthanide complexes of (2-ethylhexyl) phosphoric acids depend on the nature of the lanthanide, the atmosphere, and the structure of the complexes.     

Selective permeation of plutonium(IV) through supported liquid membrane containing 2-ethylhexyl 2-ethylhexyl phosphonic acid as ion carrier

The selective transport of plutonium across supported liquid membrane using an indigenously synthesized 2-ethylhexyl 2-ethylhexyl phosphonic acid (KSM-17, equivalent to PC 88A) dissolved in dodecane as carrier has been investigated in this work. Laminar type polypropylene hydrophobic microporous membranes were used as solid supports. Transport experiments were carried out to evaluate the effect of varied hydrodynamic and chemical compositions of the system, i.e., stirring speed, carrier concentration, anionic composition (e.g. SO²⁻₄, NO⁻₃, PO³⁻₄, ClO⁻₄, Cl⁻) and acidity of source phase (SP) solution. Transport rates of plutonium from SP solutions of different anionic composition followed the order: ClO⁻₄>NO⁻₃>Cl⁻>SO²⁻₄>PO³⁻₄. Selective permeability of plutonium was observed in the presence of several cationic impurities such as Al, B, Be, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Si, Zn, Ce, Dy, Eu, Gd and Sm. Using this technique, separation of plutonium from laboratory analytical waste was accomplished with an average flux 8.94×10⁻⁶ mol m⁻² s⁻¹ and with an enrichment factor greater than 2. The product solution obtained from this process was in oxalate medium with negligible contamination from other cationic and anionic impurities. From this solution, plutonium was precipitated as Pu-oxalate for further processing. Reusability of the membrane support was found to be satisfactory.     

Solvent extraction separation of tin (IV) with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A)

Solvent extraction of tin(IV) from hydrochloric acid media was carried out with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in toluene. Tin(IV) was quantitatively extracted with 2.5x10(-2) M PC-88A in toluene from 0.1-0.3 M HCl when equilibrated for 5 min. Tin(IV) from the organic phase was stripped with 4 M HCl and determined spectrophotometrically by both the morin and pyrocatechol violet method. The nature of the extracted species was determined from the log-log plots. Various other diluents such as xylene, hexane and cyclohexane also gave quantitative extraction of tin. The metal loading capacity of the reagent was found to be 0-15 ppm of tin(IV). The extraction of tin(IV) was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. Tin(IV) was successfully separated from commonly associated metal ions such as antimony(III), bismuth(III), lead(II), thallium(I), copper(II), nickel(II), etc. The method was extended for determination of tin in real samples.     

Solvent extraction of rare-earth metals with bis(2-ethylhexyl)phosphinic acid

 The extraction behavior of tervalent rare-earth metals (Ln) using a heptane solution containing bis(2-ethylhexyl)phosphinic acid (PIA-8, HR) from 0.1 mol/dm³ sodium perchlorate media was studied. The pH_0.5 values and separation factors obtained were compared among the metals. The stoichiometry of the extracted species and the extraction constants for the present aqueous/heptane system were determined by slope analysis. It is demonstrated that the rare-earth metals were extracted as monomers LnR₃⋅mHR (m=3, 4, 5 or 6), and the extracted species could be stripped into a relatively low concentrated hydrochloric acid. PIA-8 was found to be the most selective extractant for the mutual separation of rare-earth metals among the other phosphinic acids reported. Received: 27 February 1996/Revised: 13 May 1996/Accepted: 21 May 1996     

Determination of phthalic acid, mono-(2-ethylhexyl) phthalate and di-(2-ethylhexyl) phthalate in human plasma and in blood products

Pretreatment for the determination of phthalic acid, mono-(2-ethylhexyl) phthalate (MEHP) and di-(2-ethylhexyl) phthalate (DEHP) in human serum or plasma, and the determination of these compounds in blood products by high-performance liquid chromatography was studied. The amount of phthalic acid, MEHP and DEHP, migrated into blood products from a flexible bag, was studied. About 0.1% of DEHP in a flexible bag was found to have migrated into human platelet plasma. Most of the MEHP and phthalic acid detected in human platelet plasma was not derived from the flexible bag but was produced by enzymatic hydrolysis of the migrated DEHP. The amount of DEHP eluted into blood products from the flexible bag differed, depending upon storage time, storage temperature, etc.     

In situ electro-oxidation and liquid-liquid extraction of cerium(IV) from nitric acid medium using tributyl phosphate and 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate

The process of in situ electro-oxidation of Ce(III) to Ce(IV) followed by its extraction into the organic phase has been investigated for its applicability in the separation of Ce from nitrate medium. Solvent extraction of cerium from nitric acid after its electro-oxidation to fourth valency state was carried out using tributyl phosphate (TBP) and 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (KSM-17, equivalent to PC-88A). The efficiency of the extractants at different aqueous phase nitric acid concentrations and different electrode potentials were determined. Various reducing agents such as hydroxylamine hydrochloride, sodium nitrite, ferrous sulphate as well as complexing agents like EDTA, oxalic acid etc, were studied as strippants for the back extraction of cerium from the loaded organic phase. The method developed for the extraction of cerium was further extended to the partitioning of cerium from Ce-Am mixture obtained during the KSM-17 based extraction chromatographic elemental fractionation of PUREX High Activity Waste (HAW) solutions. Recovery of Ce obtained in the extraction experiments by batch as well as by continuous flow organic phase was >95% with good radiochemical purity.     

Extraction of actinium with di (2-ethylhexyl) phosphoric acid from hydrochloric and nitric acid solutions

The extraction of actinium with HDEHP from Cl^– and NO ₃ ^– systems has been investigated. It was found that extraction of actinium from HCl solutions is much better than from HNO₃ solutions. Stability constants of the actinium complexes Ac(X^–)²⁺, X^–=Cl^– or NO ₃ ^– , were determined. Our results show that actinium formed less stable complexes with Cl^– than with NO ₃ ^– ligands.