Interference of elements upon extraction by macrocyclic extractants

The extraction of cations of a series of alkali and alkali-earth metals, along with Pb(II), Rh(III), and Pd(II) with crown, thiacrown and azacrown ethers from picric and nitric acid solutions was studied. Upon the extraction of metal cations with macrocyclic extractants, the interference of those cations on the extraction of one another was observed in polar solvents. The causes of this phenomenon are revealed, and a mechanism for the suppression of extraction of the microcomponent with the macrocomponent is proposed. Upon the simultaneous extraction of americium (III) and europium (III) with calixarenes the co-extraction was noted for the first time, resulting in the good extraction of Am(III) from nitric acid solutions. We hypothesize on the formation of a mixed nitrate complex of americium and europium that can be effectively extracted into an organic phase with calixarenes.     

New capabilities in extraction of platinum metal chloride complexes with oxygen-containing extractants

The efficiency of extraction of platinum metal chloride complexes with oxygen-containing extractants can be increased in going from acid chloride solutions to mixed acid sulfate-chloride solutions.     

Influence of hydrophobic solids upon the extraction capability of extractants

The influence of solid phase media such as multilayer porous polymer films (nuclear filters) upon extraction of U(VI), Fe(III) and Sc by using main classes of extractants: tributyl phosphate (TBP), tributylphosphine oxide (TBPO), di-(2-ethylhexyl)phosphoric acid (HDEHPA), trioctylammonium nitrate (TOA) have been studied. The increase of distribution coefficients (D) up to 10–100 times in the presence of nuclear filters as compared to common liquid-liquid extraction has been established.     

Liquid-liquid extraction of isothiocyanic acid by high-molecular-weight extractants

Data on the extraction of isothiocyanic acid, and the co-extraction of water, by several high-molecular-weight extractants, viz. three amines, a substituted quaternary ammonium salt, a tertiary amine oxide, a tertiary phosphine oxide and a phosphate ester are reported. The extraction constants decrease in the order Primene > Amberlite > Alamine ≫ TOPO > TBP. As for AlamO, evidence is presented that 2AlamO·HNCS is formed besides the normal adduct AlamO·HNCS. With all the extractants, except the phosphate ester, the isothiocyanate adducts have a nearly pure ion-pair structure.The majority of the extractants easily take up isothiocyanic acid in excess of the stoichiometric amount. The extraction constants decreas in the order Aliquat>Alamine>AlamO>Amberlite>TOPO>Primene>TBP.     

Solvent extraction in hydrometallurgy: the role of organophosphorus extractants

Solvent extraction (SX) has come to be one of the most important separation processes in hydrometallurgy. Phosphorus-based extractants have proved to be of particular importance, especially for the separation of cobalt from nickel. However it was not until the dialkyl phosphinic acid reagent, CYANEX 272, and its dithio analogue CYANEX 301, became available that liquors containing very low Co:Ni ratios of at least 1:40 to even >1:100 could be treated. This has opened the way to the direct application of SX for the separation of Co from Ni in liquors derived from the leaching of nickel mattes from the smelting of nickel sulphide ores and from the pressure acid leaching of nickel laterite ores. This paper describes the development of the range of Cytec extractants and, in particular, discusses the development of their application for the separation of cobalt from nickel. Examples of actual industrial operating plants will also be given and individual flowsheets discussed.     

Solvent extraction of europium from aqueous-organic solutions by solvating extractants

The partition of Eu(III) between benzene containing solvating extractants (TBP, TOPO, dioctylsulfoxide) and aqueous nitrate, perchlorate and thiocyanate solutions containing various organic solvents miscible with water (alcohols, acetone, acetonitrile, ethylene glycol, dimethyl sulfoxide and dimethylformamide) was investigated. Depending on the specific extraction system, the presence of organic solvents in the mixed phase showed various effects on the distribution ratio of Eu(III). These were discussed in terms of solute-solvent interactions. The results in the systems containing dimethylformamide and dimethyl sulfoxide indicated complexation of Eu(III) with these solvents in the polar phase.     

中性萃取剂协同萃取研究

前言自从发现协同萃取以来,许多作者对协同萃取进行了广泛的研究。Reddy等人应用亚砜等中性萃取剂研究了两种中性萃取剂的协同萃取(以下简称B-B类协萃),认为在第一萃取剂(S~Ⅰ)浓度([S~Ⅰ])固定时,萃取分配比D的对数值对第二萃取剂(S~Ⅱ)的浓度([S~Ⅱ])的对数值作图是直线,其斜率为S~Ⅱ的溶剂化数n,随[S~Ⅰ]的增加直线斜率逐渐下降。似乎难以用斜率分析法来确定溶剂化数目。本文研究了二-正-辛基亚砜(以下简称DOSO),TBP和TOPO从NH_4SCN溶液中萃取Ce(Ⅲ)。分析了实验数据,提出了B-B类协萃分配比D的计算公式。     

Polydentate neutral organophosphorus compounds as extractants of transplutonium elements

Solvent extraction of ²⁴¹Am, ²⁴⁴Cm, ²⁴⁹Bk, ²⁵²Cf, ²⁵³Es, ^152–154Eu and ²³³U from 1 to 15 M HNO₃ solutions by a number of polydentate neutral organophosphorus compounds has been studied. The effect of the reagents structure on their extraction capacity, and selectivity has been investigated. Extraction by tetraphenylmethylenephosphine dioxide, which proved to be the best reagent studied, has been studied in detail. It is shown that this compound may be used for quantitative group extraction and concentrating of transplutonium elements from 1 to 15 M HNO₃ and from nitrate solutions of arbitrary concentration and acidity.     

Use of complex-forming agents for extraction separation of cerium group of rare-earth elements in systems with neutral organophosphorus extractants

The use of complexons: nitrilotriacetic (NTA) and diethylenetriaminepentaacetic (DTPA) acids have been studied in extraction systems with main classes of neutral organo phosphorus extractants: phosphates (tributyl phosphate-TBP), phosphonate (diisooctylmethyl phosphonate-DiOMP) and phosphine oxides (triisoamylphosphineoxide-TiAPO) to separate lanthanides of the Ce subgroup. Optimal conditions to use complexon have been determined (extractant and salting agent concentrations). The effect of the type of extractant on the lanthanide distribution coefficients' dependence on pH of equilibrium water solution have been studied in the presence of NTA and DTPA. Unextractable cation displacers have been used to regulate distribution coefficients. The values of lanthanide separation coefficients of Ce group have been determined in extraction systems with neutral phosphorus-containing extraction agents — complexon — salting agent compared with Nd macroconcentrations and for lanthanide microconcentrations in the presence of cation displacer. These systems have been shown to be suitable for lanthanide separation of the cerium group.     

Influence of pH on distribution coefficients of lithium and impurity elements in sorption

The possibility of purifying lithium-containing solutions to remove chemical impurities by sorption in the batch mode was examined. Sulfonic (KU 2-8, Purolite C100, Resinex KW-8), carboxylic (SG-1, Purolite C104FL, Resinex KW-H), and phosphoric acid (Purolite S957) cation-exchange resins were used as sorbents. The distribution coefficients of lithium and impurity elements (sodium, potassium, magnesium, calcium, iron) at different pH values were determined experimentally. The lithium/impurity separation factors were calculated.     

Comparative distribution coefficients and cation-exchange behaviour of the alkaline earth elements with various complexing agents

Equilibrium distribution coefficients are presented for the alkaline earth metals Be(II), Mg(II), Ca(II), Sr(II) and Ba(II) with the complexing agents acetate, formate, lactate, citrate, tartrate, alpha-hydroxyisobutyrate, malonate, malate, acetylacetonate, EDTA, EGTA and DCTA, and the AG50W-X8 cation-exchange resin. Coefficients in HCl, HNO(3), HClO(4) and NH(4)Cl are included for the sake of completeness. The merits of the various complexing agents for the separation of adjacent element pairs are discussed and experimental elution curves are presented for selected separations. Separation factors for adjacent elements are calculated at eluting agent concentrations corresponding to a distribution coefficient of 10 for the less strongly absorbed element and are presented together with the eluting agent concentrations to form a basis for comparison.     

螯合-螯合萃取剂对铀(VI)的协同萃取

有关协同萃取的研究已十分广泛,但文献报道的大多是有关螯合(或酸性磷)-中性萃取剂组成的协萃体系,关于螯合-螯合萃取剂对金属离子的协萃研究报道甚少。Newman[1],Sekine[2.3]以及Sudersanan等[4-6]曾研究过β-二酮类萃取剂之间的协同萃取,但这类体系的协萃机理和规律性尚有待探讨。本文研究了1-苯基-3-甲基-4-苯甲酰基-5-吡唑啉酮-(PMBP)与噻吩甲酰三氟丙酮(TTA)及PMBP与1-苯基-3-甲基-4-三氟乙酰-5-吡唑啉酮-(PMTFP)两种协萃体系从硝酸介质中对铀(VI)的萃取,这两种协萃体系文献中均未见报道.采用斜率法测求协萃配合物组成,计算了它们的干衡常数,并对协萃反应机理和规律性进行了讨论。     

Study of group IV–VI B metal extraction by easily melting acid extractants

The melt extraction of Ti, Zr, Hf, Nb, Cr and Mo with β-diketones in naphthalene-biphenyl eutectics has been studied and the temperature dependence of the equilibrium constants obtained. X-ray fluorescence determination of the elements in the solidified organic extract is convenient.     

Estimation of phosphorus-containing impurities in organophosphorus extractants and their distribution coefficients from the total phosphorus content of the phase in equilibrium with the extractant phase

The total phosphorus content of stripping solutions after their equilibration with organophosphorus extractants in successive contacts with fresh strip solution was employed to estimate the concentrations of phosphorus-containing hydrolysis (or degradation) products in the extractant phase and their distribution coefficients. Aqueous solutions and ethylene glycol were used as stripping agents. The procedure is especially useful for estimates of the concentrations of phosphorus-containing impurities that are originally present in the extractant or that are generated in separations processes. The utility of the method was demonstrated for separations processes that employ the following extractants: di-(2-ethylhexyl)-phosphoric acid, tributyl phosphate, and dihexyl-N, N-diethylcarbamylmethylenephosphonate.     

Synergic extraction of cobalt(II) by thenoyltrifluoroacetone and some amine extractants in chloroform

Synergic extraction of Co²⁺ with thenoyltrifluoroacetone and eight different amines in chloroform was investigated. It is found that the extracted adducts have the general formula Co(TTA)₂·B, where B stands for the amine. The stability sequence of the adducts obtained as related to the different classes of benzylamines is; dibenzylamine > benzylamine ⩽ tribenzylamine. A linear decrease in log β with the increase of Taft inductive constant was obtained on using tertiary long chain alkylamines as synergic ligand. UV and IR spectroscopic investigations support the direct bonding of the amine to the metal.     

Reactive extraction of penicillin II: Distribution coefficients and degrees of extraction

The equilibrium constants and degrees of extraction of penicillin G are investigated by using primary, secondary and tertiary amines as carriers and a