Solvent Extraction Behavior of Cerium(IV), Zirconium,and Thorium with Liquid Ion Exchangers

Abstract

The systematic solvent extraction behavior of cerium(IV), zirconium, and thorium has been studied with the high molecular weight carboxylic acids SRS-100 and Versatic-9, with benzene as diluent. Quantitative extraction has been achieved in almost all cases. Only in the case of zirconium has incomplete extraction (73.5%) been reported with Versatic-9. Quantitative extraction requires three consecutive equilibrations at pH 2.9. The effect of metal ion concentration, solvent concentration, diluents, and the interference of the associated elements were critically examined. The percentage extraction at various ranges of pH has been studied. Exchange reaction techniques have been employed in several systems. The proposed methods are very simple, rapid, and fairly selective. They can be carried out both at micro and macro levels, and they are applicable to extraction of metal ions in the presence of other commonly interfering ions.     

Solvent Extraction Behavior of Transitional Metals with Liquid Ion-Exchangers

Abstract

A systematic study of the comparative extraction behavior of some transitional metals has been performed with the high molecular weight carboxylic acids, SRS-100 and Versatic-9, using benzene as diluent. The study includes the extraction behavior as a function of pH, effect of diluent, metal ion concentration, solvent concentration, salting-out agent, and finally interference of the associated elements. Exchange reaction for several systems are reported. In almost all cases nearly quantitative extraction has been achiaved. It has been found that the extraction is rapid and complete within 3–4 min but the optimum period of extraction is kept at 5 min. In some cases quantitative separations have also been carried out.     

Studies of Solvent Extraction Behavior of Some Divalent Metals with Liquid Ion-Exchanger

Abstract

A systematic study of the comparative extraction behavior of some divalent metals has been carried out with the high molecular weight carboxylic acid, namely SRS-100. Benzene is used as diluent. The study includes the extraction behavior as a function of pH, effect of diluent, metal ion concentration, solvent concentration, and finally interference of the associated elements. In almost all cases nearly quantitative extraction has been achieved. The proposed method is very simple, rapid, and is applicable both at micro and macro levels. The. method is applicable to extraction of metal ions in the presence of other commonly interfering ions present at the milligram level.     

Separation of Osmium(VIII) from Platinum Group Metals by Extraction with Liquid Ion Exchangers

Abstract

A method is developed for the extraction and separation of osmium from palladium, platinum, ruthenium, rhodium, and iridium with tri-n-octyl amine either from hydrochloric or hydrobromic acid solutions. The extracted species is (R₃NH⁺)₂OsCl₆ ^2-. The method is shown to be applicable to synthetic mixtures.     

Equilibrium and Behavior of Trivalent Metal Ion Extraction with N-p-Octyloxybenzoyl-N-Phenylhydroxylamine

A study of the extraction of the trivalent metal ions Fe, Ga, In and Al, was carried out with benzene solutions containing N-benzoyl-N-phenylhydroxylamine and N-p-octyloxybenzoyl-N-phenylhydroxylamine(HL), respectively. The results demonstrated that the metal ions were extracted as ML₃ for Fe, Ga and In, M(OH)L₂ for Al (where M is metal ion). The extraction constants and separation factors for the two extractants were compared.     

Solvent Extraction,Membranes, and Ion Exchange in Hydrometallurgical Dilute Metals Separation

Abstract

The separation methods which are used in the hydro-metallurgical field are reviewed and compared. Some processes in solvent extraction in use for recovery of crucial metals which are important to the U.S. defense and economy are presented. Various commercial extractants are reviewed and categorized. Other methods such as liquid membranes and ion exchange resins used for dilute metal ions separation are summarized. These methods are compared with solvent extraction. Problems to overcome in the further development of these separation methods are also identified and discussed in this paper.     

Ion Sequestration,Solvent Extraction and Antimicrobial Behavior of Quinoline Functionalized Chitosan

Chemically modified chitosan incorporating amino quinoline was prepared by reacting 6-amino-2-chloroquinoline-3-carbaldehyde with chitosan; it was found to have high selective and chelating efficiency towards transition metal ions at pH 1–8. Enhanced adsorption capacity and strong affinity for Cu²⁺ was observed as compared to Cd²⁺, Ni²⁺, and Co²⁺ at 4–6 pH. This selectivity appeared to be independent of the size and the hardness of the ions. Potentiometric methods confirmed the order of selectivity which was independent of physical form of chitosan-amino-quinoline derivative (CAQ). CAQ was chemically synthesized and characterized by ¹HNMR, ¹³CNMR, and FTIR techniques. ¹HNMR results suggested a degree of substitution (DS) ranging from 14.6 to 95.2%. The adsorption capacity, ion selectivity of CAQ and antimicrobial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans were investigated. Our results prompted us to further investigate the utility of CAQ as a green depolluting agent. The new chitosan-amino-quinoline derivative showed elevated potential as a good adsorbent, depolluting agent having selective memory for metal ions, and could be utilized especially for ion sequestration and solvent extraction.     

有机磷(膦)酸对碱土金属的萃取

Solvent extraction equiliria of four main alkaline earth metals (magnesium, calcium, strontium and barium) with di(2-ethylhexyl) phosphoric acid (DEHPA), 2-ethylhexyl phosphonic acid mono-(2-ethylhexyl) ester, di(2,4,4-tri-methylpentyl) phosphinic acid and IR spectra of the extracts have been studied. The selectivity order is dependent of the e/r value and hydration energy of the metal ions. The minor shift of the P→O in IR absorption of the alkaline earth metal extracts indicates that the interaction between the metal ions and P→O is much weaker for alkaline earth metals than for transitional metals. The distribution of the four alkaline earth elements between aqueous solutions and solutions of DEHPA and neutral organophosphorus compunds, tri-n-butyl phosphate (TBP) or tri-octyl phosphine oxide (TOPO) in kerosene have been determined at varying ratio of TBP or TOPO to DEHPA and the positive synergism is observed. The synergic effects is explained by using IR spectra of the loaded organic phase.     

Solvent Extraction Separation of Selected Transition Metals with Mesityl Oxide

Abstract

Mesityl oxide (4-methyl-3-pentene-2-one) has been used for the solvent extraction studies of some transition metals such as Th, Zr, U, Pd, Pt, V, Cr, Mo, W, Re, Fe, Au, and Ga. In the present article optimum conditions for the extraction of the above metals have been given based on a critical survey of the relevant factors such as the effect of acid concentration, reagent concentration, salting-out agent, period of extraction, and diverse ions. The mechanism underlying these extractions is also discussed. The mesityl oxide has proved to be an excellent extractant as it provides clean-cut separation of a large number of ions in minimum time.     

Solvent Extraction Separation of Trivalent Americium from Curium and the Lanthanides

The sterically constrained, macrocyclic, aqueous soluble ligand N,N′-bis[(6-carboxy-2-pyridyl)methyl]-1,10-diaza-18-crown-6 (H₂BP18C6) was investigated for separating americium from curium and all the lanthanides by solvent extraction. Pairing H₂BP18C6, which favors complexation of larger f-element cations, with acidic organophosphorus extractants that favor extraction of smaller f-element cations, such as bis-(2-ethylhexyl)phosphoric acid (HDEHP) or (2-ethylhexyl)phosphonic acid mono(2-ethylhexyl) ester (HEH[EHP]), created solvent extraction systems with good Cm/Am selectivity, excellent trans-lanthanide selectivity (K_ex,Lu/K_ex,La = 10⁸), but poor selectivity for Am against the lightest lanthanides. However, using an organic phase containing both a neutral extractant, N,N,N’,N’-tetra(2-ethylhexyl)diglycolamide (TEHDGA), and HEH[EHP] enabled rejection of the lightest lanthanides during loading of the organic phase from aqueous nitric acid, eliminating their interference in the americium stripping stages. In addition, although it is a macrocyclic ligand, H₂BP18C6 does not significantly impede the mass transfer kinetics of the HDEHP solvent extraction system.     

离子液体作溶剂和催化剂合成螺环磷酰二氯

离子液体[Bmim]BF4既作溶剂又作催化剂合成了螺环磷酰二氯(SPDPC),在原料季戊四醇与三氯氧磷的摩尔比为1∶2.2,反应温度40℃,反应时间7 h的条件下,产率达66%。用熔点、IR和1HNMR表征了SPDPC的结构。推测了离子液体的催化机理。合成方法与文献典型的方法做了比较,结果发现,用离子液体作溶剂和催化剂,不但缩短了反应时间,降低了反应温度,而且不挥发,易回收,经济、环保,是合适的合成SPDPC的溶剂和催化剂。     

离子液体作溶剂合成螺环磷酰二氯

用离子液体既作溶剂又作催化剂合成了螺环磷酰二氯（SPDPC）,原料季戊四醇与三氯氧磷的摩尔比为1:2.2,反应温度40℃,反应时间7h,产率66%。用熔点、IR和1HNMR表征了SPDPC的结构。推测了离子液体的催化机理。合成方法与文献典型的方法做了比较,结果发现,用离子液体作溶剂和催化剂,不但缩短了反应时间,降低了反应温度,而且不挥发,易回收,经济、环保,是合适的合成SPDPC的溶剂和催化剂。     

Solvent Extraction and Separation of Trivalent Lanthanides Using Cyphos IL 104, a Novel Phosphonium Ionic Liquid as Extractant

Solvent extraction of trivalent lanthanides from chloride solution using a novel ionic liquid Cyphos IL 104 (trihexyl(tetradecyl)phosphonium bis-2,4,4-(trimethylpentyl) phosphinate or [R₄PA]) has been investigated, while comparing the results with that of its precursors trihexyl(tetradecyl)phosphonium chloride [R₄PCl or Cyphos IL 101], Cyanex 272 [HA] and their equimolar mixture. The results also indicate very high extractability of Cyphos IL 104 toward trivalent lanthanides. Unlike the conventional acidic extractants, extraction of trivalent lanthanides with Cyphos IL 104 increases the equilibrium pH of the aqueous phase due to the preferential extraction of acid over the lanthanide ions. Extraction mechanism has been established by studying the extraction of neodymium(III) with the ionic liquid as a function of the concentrations of Cyphos IL 104 and chloride ions. Separation studies of trivalent lanthanides from a mixed solution containing 1 × 10^?4M each of La, Nd, Gd, and Lu with Cyphos IL 104 or Cyanex 272 indicate that Cyphos IL 104 is a better extractant in terms of extraction coefficient, but Cyanex 272 exhibits better selectivity toward heavier lanthanides. The prospects of stripping and regeneration of ionic liquid (Cyphos IL 104) have also been discussed in the present study.     

Cyanex 923在金属溶剂萃取中的应用

Cyanex 923是一种有机氧化膦类萃取剂,具有萃取容量高,选择性好等特点。介绍了Cyanex923的性质,对Cyanex 923在重金属废水处理、稀土金属和贵金属萃取的应用研究现状进行了综述。     

Extraction Behavior of Americium and Plutonium with Mixed Solvent Extractants

Abstract

The mixed solvent extractants, dibutyl N,N-diethylcarba-moylmethylenephosphanate (DBDECMT)-tributyl phosphate (TBP), using carbon tetrachloride diluent, were studied for extracting americium (III) and plutonium (IV) from 0.35 and 7M HNO₃ at 25°C. Synergistic effects were observed in this system as was the case with preliminary results (described herein) using the dihexyl analogue DHDECMP and TBP.     

Ion Flotation and Solvent Extraction of Ferric Thiocyanate Complexes

Abstract

The influence of thiocyanate and accompanying mineral acids concentration on the effectiveness of Fe(III) ion flotation, Fe(III) precipitation in cetyl-trimethylammonium ferric-thiocyanate form (as sublate), and Fe(III) extraction using ethyl acetate was studied. The effectiveness of these processes improves with the extent of Fe(III) complexation by thiocyanates. In the presence of acids, flotation and precipitation are increased as follows: HC1O₄ < HC1 < HNO₃ < H₂SO₄. The position of H₃PO₄ in this series changes with changing thiocyanate concentration. Extraction effectiveness is increased in the series: H₃PO₄ < H₂SO₄ < HNO₃, HC1O₄ HCl. The following points are discussed: (a) the influence of acid anions competing with thiocyanate anions in Fe(HI) complexation; (b) the influence of the competition between acid anions and complex ferric-thiocyanate anions in sublate formation; (c) the influence of hydrogen ion concentration increase in thiocyanate medium on the results of Fe(III) flotation, precipitation, and extraction; and (d) the influence of anion affinity for a collector on the solution surface properties and on Fe(III) flotation.     

Mass Transfer Rate with Liquid Ion Exchangers. The Role of Interfacial Chemical Reactions in the Extraction Kinetics by Dinonylnaphthalenesulphonic Acid and Trilaurylammonium Salts

Kinetics and interfacial tension studies concerning the liquid cation exchanger dinonylnaphthalene sulphonic acid (HD) and the liquid anion exchangers trilauryl-ammonium chloride and nitrate (TLAHCI and TLAHNO₃), performed in the laboratory, are reviewed. The interfacial tension studies have shown that, due to the very strong surface active properties of these compounds, even at very low bulk organic concentrations, the interfacial plane gets completely saturated with a strongly adsorbed monomolecular layer of the exchanger. The structure of the interface is such that the ion-exchange group faces the aqueous phase while its organic part is completely immersed in the organic diluent. Extraction kinetic experiments performed with a quiescent interface cell (Lewis cell) as a function of the stirring speed, interfacial area and volume of the phases have shown that (a) a region always exists where the extraction kinetics is independent of the stirring speed and (b) the exchange kinetics is directly proportional to the interfacial area and inversely proportional to the volume of the phases. These two facts, together with the knowledge of the interfacial structure of the exchanger, are a strong indication that interfacial chemical reactions can have a predominant effect in determining the extraction kinetics. Experiments performed at relatively high stirring speeds of the phase as functions of the chemical composition of the system have produced a set of interfacial chemical reactions which completely describe the kinetics of the liquid ion-exchange process. This set of reactions consists basically of the following steps: (a) formation of an interfacial complex between the interfacially adsorbed molecules of ion-exchanger and the metal cation or complex present in the aqueous solution, (b) replacement at the interface of the interfacial complex with bulk organic molecules of the ion-exchanger; this process, with a rate which is proportional to the organic concentration of the exchanger, occurs through the reaction with bulk molecules of the extractant, and (c) the reverse steps occur when organic to water transfer takes place. By applying the stationary condition to the interfacial complex its concentration has been evaluated and a rate expression derived which has led to the calculation of the rate constants of the chemical reactions. The following metal ions have been studied experimentally: Fe+³, Eu+³, Ce+³, Gd+³, Tm+³ with HD; FeCln³-n with TLAHCI and Pu(NO₃)n⁴-n with TLAHNO₃. By using the derived rate expressions and rate constants, distribution laws have been obtained to calculate equilibrium distribution data in good agreement with experimental results.     

Separation of Ionic Liquid Dispersions in Centrifugal Solvent Extraction Contactors

Abstract

Separations of dispersions formed by mixing immiscible organic room‐temperature ionic liquids (IL)/hydrocarbon/and aqueous systems using a centrifugal solvent‐extraction contactor have been successfully demonstrated in proof‐of‐concept testing. This accomplishment is significant in that physical property factors that are typical of ionic liquid systems (e.g., similar densities of the bulk phases, low interfacial tensions, and high viscosities) are typically unfavorable for dispersion separation, particularly in continuous processes. Efficient separation of dispersions containing ionic liquid solvents is essential for utilization of these compounds in liquid‐liquid extraction applications to maximize both solute transfer efficiency and solvent recovery. Efficient solvent recovery is of particular concern in IL applications because of the high cost of most IL solvents.

This paper presents the results of initial experiments with three hydrophobic ionic liquids to determine how their physical properties affect phase mixing and phase disengagement in contact with an aqueous solution using a centrifugal contactor. While the results of the reported work are promising, additional work is needed to optimize existing mathematical models of contactor hydraulics to address special considerations involved in IL‐based processes and to optimize the equipment itself for IL applications.     

Role of Phase Modifiers in Controlling the Third-phase Formation During the Solvent Extraction of Trivalent Actinides

ABSTRACT

Diglycolamides have been proposed for partitioning of trivalent actinides from high-level liquid waste (HLLW). Third-phase formation is an undesirable event during the course of solvent extraction of trivalent actinides from HLLW into the solution of N,N,N’,N’-tetra(2-ethylhexyl)diglycolamide (TEHDGA) in n-dodecane (n-DD). Polar reagents such as tri-n-butyl phosphate (TBP), and N,N-dihexyloctanamide (DHOA) have been added to the TEHDGA phase, as phase modifiers in significant concentration, to overcome the third-phase formation. To understand the role of these phase modifiers in controlling the third-phase formation, the extraction behaviour of nitric acid and the trivalent representative metal ion Nd(III) was studied in a binary solution containing TEHDGA and phase modifier in n-dodecane. The organic phase obtained after extraction was subjected to dynamic light-scattering studies to examine the aggregation behaviour of the reverse micelles formed upon extraction and to unravel the unique role of TBP and DHOA in controlling the third-phase formation. The study revealed that the addition of these modifiers brought down the average size of aggregates and their distribution in organic phase below the limiting aggregate size for third-phase formation and increased the dispersion of aggregates in the n-dodecane phase. Among the two phase modifiers proposed for trivalent actinide separation from HLLW, TBP has been identified as a promising reagent for minimizing the third-phase formation.     

有机氧化膦类萃取剂在金属溶剂萃取中的应用

有机氧化膦类萃取剂,主要包括Cyanex 921、Cyanex 923和Cyanex 925等,具有萃取容量高,选择性好等特点。介绍了有机氧化膦类萃取剂的性质,对有机氧化膦类萃取剂在重金属废水处理、稀有金属和贵金属萃取的应用研究现状进行了综述。