SOLVENT EXTRACTION OF MOLYBDENUM (VI) WITH LIX 63

The equilibrium and kinetics of the extraction of molybde-num(VI) with LIX 63 was investigated. The extraction of Mo(VI) is both favored by high acidity and high LIX 63 concentration. From the equilibrium studies, the extraction constant for the reaction was found to be log K_ex - 16.43. The rate of extraction is first ex order in both metal and extractant but decreases non-linearly with pH. The rate-determining step of the reaction was deduced to be the formation of a 1:1 complex between Mo(VI) and LIX 63 in the aqueous phase. A mechanism in which different Mo(VI) species react concurrently with the neutral ligand is proposed. The logarithmic values of the second order reaction rate constants (in M^?1 s^?1 units) involving each Mo(VI) species are as follows: molybdate - 2.30, bimolybdate - 5.82, and molybdic acid - 8.16. These results agree well with the results reported for other ligands.     

SOLVENT EXTRACTION EQUILIBRIUM OF NICKEL FROM AMMONIACAL SOLUTIONS BY LIX 64N

Equilibrium data for the solvent extraction of nickel from amraoniacal solutions by LIX 64N (10 vol%) dissolved in kerosene (15% aromatic content) are reported. The effect of NH3/aq) concentration, LIX 64N concentration, pH and temperature are shown. The stoichiometry of the Ni-active oxime in LIX 64N complex was ascertained by spectrophotometry studies. A mathematical mechanistic model was developed for the prediction of extraction distribution coefficients as a function of pH. The model predicts more accurate results at high pH values, as could be expected taking into consideration the assumptions made in developing the model.     

INVESTIGATION OF SOLVENT LOSSES IN THE SOLVENT EXTRACTION OF BORON

ABSTRACT

Solubility, adsorption onto mineral particles and entrainment of 2-chloro-4-(1,1,3,3-tetramethy1-buty1)-6-methylol-phenol (CTMP) in aqueous slurry phase are considered here.

The results show that, the solubility at equilibrium increased sharply with pH, but remained at only 16 parts per million (ppm) at pH 9. With regard to adsorption onto various mineral phases considered, the affinity for CTMP increases in the order quartz < clay minerals < carbonates. The adsorption is about 9 and 13?ppm for quartz and bentonite respectively. The entrainment at pH 9.2 is about 107 and 110 gm^-3 for bentonite and the Kirka slurry respectively     

钴镍协同萃取体系

评述了自１９６６年以来报道的有关钴镍协同萃取的文献．主要介绍了磷酸、羧酸以及磺酸类萃取剂与含氮螯合萃取剂或非螯合萃取剂组成的协同萃取体系．此外，对一些由胺类萃取剂加磺酸或羧酸类萃取剂加吡啶羧酸酯组成的协同萃取也作了简单介绍．讨论了这些协同萃取体系萃取钴镍的反应机理、特点及其潜在的应用价值．     

SOLVENT EXTRACTION OF Ni(ll) WITH THE ACTIVE COMPONENT OF LIX 54

ABSTRACT

The solvent extraction of Ni(II) with the active component of the commercial extractant Lix 54 in different synergic mixtures, using tri-n-octylphosphine oxide (TOPO), tri-n-laurylamine (TLA), di-(2-ethylhexyl)phosphoric acid (HDEHP), tributylphosphate (TBP) and 4-methylpyridine as synergic reagents is compared in this work, the highest synergic effects corresponding to the presence of TOPO and 4-methylpyridine. For this reason, the extraction of Ni(ll) from a 1.0 mol.dnr³ KN0₃media by the mixture of the active component of Lix 54 and 4-methylpyridine has been extensively studied in this work. The results have been treated both graphically and numerically in order to find a suitable chemical model of the species responsible for the extraction as well as their extraction constants.     

ANION EFFECT ON SELECTIVITY IN SOLVENT EXTRACTION OF ALKALI METAL SALTS BY CROWN ETHERS

ABSTRACT

The influence of the co-extracted anion upon competitive solvent extraction of five alkali metal cations from aqueous solutions into organic diluents by the cis-syn-cis and cis-anti-cis isomers of dicyclohexano-18-crown-6 has been assessed. The anions are bromide, chloride, iodide, nitrate, perchlorate, and thiocyanate and the organic diluents are chloroform and 1-octanol. The extraction efficiency is markedly influenced by the identity of the anion and exhibits some correlation with the inverse of the hydration enthalpy of the anion. Although potassium is the best extracted cation with all anions, the selectivities for potassium over lithium, sodium, rubidium, and cesium are strongly affected by anion variation in chloroform, but not in 1-octanol. The selectivity ordering in chloroform does not correlate with the hydration enthalpy or softness parameter for the anion. Instead it appears to result from variation of the dimensional structure and the availability of specific binding sites in the anion.     

SPECTROSCOPIC STUDY OF THE EXTRACTION OF NICKEL BY 2-HYDROXY-5-NONYLBENZOPHENONE OXIME (LIX 65N) AND 5,8-DIETHYL-7-HYDROXYDODECANE-6-ONE OXIME (LIX 63).

ABSTRACT

A novel method for determination of solvent extraction equilibria and kinetics using Infrared attenuated total reflectance spectroscopy (ATR) is described. The method allows complete, quantitative kinetic studies using a total of one gram of extractant. Solvent extraction of aqueous Ni²⁺ into 0.5 - 1.0 μm films of Apiezon M (ApM, aliphatic hydrocarbon) containing the title reagents was examined. In contrast with LIX 65N extraction which proceeds solely through the LIX 65N anion, extraction of Ni²⁺ by LIX 63 proceeds through both neutral and anionic forms of LIX 63. This results in a kinetic rate law having two terms, each exhibiting first order dependence on both [Ni²⁺] and [LIX 63]₀. For mixtures of LIX 65N and LIX 63 (LIX 63:LIX 65N ≤ 0.12) In the ApH films, the rate law has only one term, of orders [LIX 65N]₀ ¹, [LIX 63] ₀ ¹, [Ni²⁺]¹, and [H⁺]^?1. While the equilibrium constants favor Ni(LIX 65N)₂, the relatively large rate of reaction of the neutral LIX 63 leads to a catalysis of the overall LIX 65N extraction.     

SOLVENT EXTRACTION OF COPPER(II) WITH THE ACTIVE COMPONENT OF LIX 54. SYNERGIC EFFECT IN THE PRESENCE OF TRI-n-OCTYLPHOSPHINE OXIDE.

The extraction of Cu(II) from nitrate medium of ionic strength 1.0 mol.dm^-3 by l-phenyl-l,3-decanedione (HR) and by the mixture 1-phenyl-l,3-decanedione and tri-n-octylphosphine oxide (TOPO), dissolved in toluene, has been studied by distribution methods. The experimental data treated both graphical and numerically can be explained assuming the formation in the organic phase of the species CuR₂ and Cu(NO₃)R. The synergic effect found in the presence of TOPO has been explained by the formation of the complex CuR₂(TOPO). Equilibrium extraction constants for the species are given.     

乙醇抽提大豆油之研究

<正> 大豆产于我国已有长久历史,产量向居世界第一位.据1949年统计,全世界大豆产量为501,700,000英斛(bushel)(1 bushel=8加侖),中国产量为245,200,000英斛,约占全世界产量二分之一弱;1935—1939年世界平均产量为464,300,000英斛,中国为369,111,000英斛,约佔四分之三强,故大豆为我国国宝之一.大豆不但含有丰富之蛋白质等,为极佳之食品,且平均含油量达18%左右,为吾国同胞食油之主要来源.     

膜萃取防止溶剂污染的优势

本文以３％ＴＢＰ／苯酚／水为实验体系在不同的膜器中对膜萃取过程中料液对萃取剂的夹带,即溶剂的二次污染进行了研究。在保持膜两侧压降不变的情况下对进口和出口处料液的ＣＯＤ值进行了测定,并与传统的溶剂萃取方法相比较。结果表明,膜萃取中料液中溶剂只有少量的夹带,并且夹带量与操作条件和膜构件基本无关。     

THIRD PHASE FORMATION IN THE SOLVENT EXTRACTION SYSTEM FeCl3-HCl-H20-DIPE

The influence of the initial aqueous concentrations and the temperature on the volumes and compositions of the phases obtained in the FeCl₃-HCl-H₂0-DIPE system have been investigated.The low temperature limit to the three phase system suggests that the appearance of the second organic phase is associated with an increase in entropy due to the separation a weakly ordered, predominantly solvent, phase.     

MATHEMATICAL MODEL FOR METAL SOLVENT EXTRACTION SYSTEMS, SELECTIVITY EFFECT

A mathematical model based on matrix notation is used to study the behavior of liquid-liquid extraction systems in hydrometallurgical processes. One major advantage of the model is that the ion concentration effect on the phase equilibrium is considered. The model is based on the solution of a set of nonlinear equations. The calculation method is presented and the correction algorithm is derived. The model is validated using published industrial plant data. The effect of the system parameters, such as, liquid resin concentration, ion concentration and pH are analyzed. The selectivity of the liquid-liquid extraction system is investigated and a correlation with the operating variables is proposed. Results for a sample problem is presented.     

ELECTROPHORETIC MOBILITY OF OIL DROPS IN THE PRESENCE OF SOLVENT EXTRACTION REAGENTS

Abstract

The electrophoretic mobility (EM) of hexane and toluene droplets dispersed in aqueous solution has been investigated as a function of pH in the presence and absence of 5,8-diethyl–7–hydroxy–6–dodecanone oxime (the active extractant in the Henkel reagent, LIX63), Dinonylnaphthalene sulfonic acid (HDNNS), di(2-ethylhexyl) phosphoric acid (HDEHP) and tricaprylyl methyl ammonium chloride (Aliquat 336). Both hexane and toluene droplets were found to be negatively charged at pH > 3, with the absolute EM increasing with pH; the toluene droplets were more negatively charged than the hexane droplets. The hydroxyoxime reagent had no significant effect on the EM, whereas the addition of HDNNS and HDEHP dramatically enhanced the negative charge at the organic/ water interface. In the presence of 1·5 × 10^?4 kmol m^?3 Aliquat 336, the organic drops became less negatively charged and eventually acquired a positive charge at pH < 9. The results are explained In terms of the preferential adsorption of the aqueous phase hydroxyl ions and the polar groups of the various extractants at the organic/water interface.     

INFLUENCE OF THE AMINE NATURE ON THE COMPOSITION OF PALLADIUM COMPLEXES IN SOLVENT EXTRACTION SYSTEMS

ABSTRACT

The extraction of palladium chloro complexes by di-n-octylamine and diamines of various structure as function of the composition of the aqueous and organic phases has been studied. The compositions of the extracted species are indicated and the mechanisms of their distribution are described. It was shown that from 1 to 3 M HC1 solutions. complexes such as (R₂NH₂)₂PdCl₄ solvated by molecules of dioctvlamine chloride are extracted. With increasing the initial concentrations of palladium or decreasing acidity of the aqueous phase, a direct coordination takes place, first of one and then two molecules of amine to atom of palladium with the formation of extracted compounds such as HC1 solutions by salts of amines, diamines and QAB ionic associates such as (AmH)₂PdCl₄, (AmH)₂)PdCl₄ and (R₄N)₂PdCl₄, respectively, are recovered into the organic phase. In systems containing trioctylamine, tetraoctylalkylenediamines (n = 4, 6) and QAB. ionic associates containing the dimeric complex anion, Pd₂Cl₆ ^2-, are also formed. When primary (n-octylaniline - OA) and secondary amines are used as extractants the formation of dimeric species in the organic phase is not observed.

The extraction of palladium from weakly acidic and neutral solutions can proceed through a combination of anion-exchange and coordination mechanisms with the formation of (AmH)[Pd(Am)Cl₃] in systems with primary and secondary amines, and through a coordination mechanism with the formation of complexes such as Pd(Am)₂Cl₂ in systems with primary, secondary and tertiary amines. When palladium is extracted by diamines with a short hydrocarbon chain (n=2) the formation of coordination compounds also takes place.     

THERMODYNAMICS OF SOLVENT EXTRACTION

ABSTRACT

The fundamental thermodynamic characteristics of aqueous electrolyte solutions and organic solutions which affect solvent extraction are summarized and the influence of metal complexation and hydration on the distribution ratios is discussed. The thermodynamics of extraction systems, including synergistic systems, is reviewed. The influence of structural aspects of the complexing extractant agents on these thermodynamic parameters is also reviewed.     

THE DEPENDENCE OF THE SELECTIVITY OF THE EXTRACTION OF SOME BATHOFERROINE ION PAIRS ON THE STRUCTURE OF WATER IN THE AQUEOUS PHASE

Abstract

The paper deals with the mechanism of increasing the selectivity of some bathoferroine (tris/bathophe-nanthroline /iron/II/cation) ion pairs by adding selected nonelectrolytes to the water phase. The dependence of the bathoferroine cation hydration number and extraction selectivity on the concentration of the nonelectrolyte and temperature has been found. The dependence of the extraction selectivity on ethanol concentration in the water phase with various solvents as the organic phase has been investigated, too. Moreover, the solvation number (ethanoi) of ion association compounds tested in conditions of the best extraction selectivity has been determined

Details concerning the behaviour of the extraction system have been discussed based on the theory of the structure of liquid water.     

DILUENT EFFECTS IN SOLVENT EXTRACTION

The empirical diluent parameters DP, introduced by Shmidt et al. several years ago, describe the extraction of mineral acids or metal complexes by the expression log K_ex = log K_ex ° + const. DP. They have now been related to independently obtainable properties of the diluents. The best correlation is with Dimroth and Reichardt's polarity index E_T, with Hildebrand's solubility parameter δ as an additional parameter causing some improvement. The new expression is: log K_ex = log K_ex ° + const₁. E_T + const₂. δ.     

用三烷基氧膦—煤油溶液从发酵滤液中萃取克拉维酸

报道了将中性磷这一高效萃取体系应用于克拉维酸的提取分离．研究了三烷基氧膦萃取克拉维酸的各种参数：ｐＨ、时间、相比、浓度等的影响，确定了最佳萃取条件及其工艺参数：３０％三烷基氧膦的煤油溶液为萃取剂，萃取平衡ｐＨ＝１．５，萃取相比Ｏ／Ａ＝１：３，并进行四级逆流萃取，饱和醋酸锂反萃，反萃平衡ｐＨ为７～７．５．     

THE KINETICS OF ZINC,COBALT AND NICKEL EXTRACTION IN THE D2EHPA-HEPTANE-HC104 SYSTEM USING THE ROTATING DIFFUSION CELL TECHNIQUE

The kinetics of the extraction of zinc, cobalt and nickel from perchlorate solutions using di 2-ethyl-hexyl phosphoric acid (D2EHPA) dissolved in heptane were studied using the Rotating Diffusion Cell technique. The extraction of each metal was investigated individually over a wide range of metal concentration, extractant concentration, pH and temperature conditions.

The data were analysed in terms of a mass transfer with chemical reaction (MTWCR) mechanism. Hughes and Rod'/s generalized MTWCR model was used to fit the cobalt data using kinetic and equilibrium parameters. The zinc and nickel data were quantitatively described within the framework of the MTWCR model. The zinc extraction rate was so fast that mass transfer alone was rate controlling. The nickel extraction experiments were so slow that the metal-ligand complex formation was incomplete in the aqueous film. Some reaction was determined to be occurring in the aqueous bulk solution as well.     

A PRECAUTIONARY NOTE ON THE USE OF DIBOTYL-N,N-DIETHYLCARBAMOYLPHOSPHONATE IN SOLVENT EXTRACTION

ABSTRACT

Investigation of dibutyl-N,N-diethylcarbamoylphosphonate (DBDECP) as a solvent extraction reagent has revealed that the commercially available compound apparently contains low concentrations of aqueous soluble impurities which drastically effect the distribution ratios obtained using tracer scale radiochemical techniques. Analysis of previously published data regarding this extractant indicates that wide variations exist in some of the reported distribution ratios obtained for this compound under quite similar conditions. Caution must be exercised, therefore, in interpreting solvent extraction data obtained with DBDECP.