SOLVENT EXTRACTION EQUILIBRIA OF GALLIUM (III) WITH ACIDIC ORGANOPHOSPHORUS COMPOUNDS FROM AQUEOUS NITRATE MEDIA

A comparative investigation on the solvent extraction equilibria of gallium(III) from aqueous nitrate media was conducted with three kinds of acidic organophosphorus compounds, di (2-ethylhexyl) phosphoric acid (D2EHPA), 2-ethylhexyl 2-ethyl-hexylphosphonic acid (EHEHPA) and di (2,4,4'-trimethylpentyl) phosphinic acid (DTMPPA), in toluene at 303 K. It was found that gallium(III) is extracted as 1:4 metal:reagent complexes with D2EHPA and EHEHPA and as a 1:3 complex with DTMPPA in the region of low loading ratio while it is extracted as 1:3 complexes with all reagents at high loading ratio. The extraction equilibrium constants with these extractants were evaluated for the former complexes as follows: K_e = 2.3xl0^-2, 8.5xl0^-3 and 1.3xl0^-4 for D2EHPA, EHEHPA and DTMPPA respectively.     

2-乙基己基膦酸单(2-乙基已基)酯萃取钴的动力学

引言膦类萃取剂萃取分离钴、镍已应用于工业生产，并在湿法冶金和其它领域得到广泛应用．对膦类萃取剂萃取钴的动力学已有多方面研究~〔1～6〕，但2-乙基已基磷酸单（2-乙基己基)酯（简称P_507,HEHEHP，H_2A_2）萃取钴的动力学研究报道较少~〔4,6〕，尤其缺乏不同水相介质对HEHEHP萃取钴的萃取速度的影响及其机制的探讨．本文在恒定界面池内，研究了HEHEHP-加氢煤油-NaNO_3体系萃取钴的动力学，主要在动力学坪区考察了萃取体系中各种因素和不同水相介质对萃取速度的影响，并对其机理进行探讨．l　实验部分1.1　仪器和试剂恒定界面…     

LEAD(II) EXTRACTION FROM NITRATE SOLUTIONS WITH DI(2-ETHYLHEXYL)PHOSPHORIC ACID

ABSTRACT

In this paper, equilibrium studies were carried out on the extraction of trace amounts of lead(II) from 0.2 mol/dm³ (Na,H)NO₃ aqueous solutions with di(2-ethylhexy1)phosphoric acid (HR) dissolved in n-dodecane at 298 K. The composition of the extracted species was numerically found to be and ₂. A chemical equilibrium model was developed to evaluate the thermodynamic constants for the formation of the two complexes, based on the law of mass action, which took into account the activity corrections of reactive species in the aqueous phase by employing the Bromley and the simplified Pitzer equations and those of the extractant in the organic phase.     

EXTRACTION OF DIVALENT METALS WITH BIS(2,4,4 TRIMETHYLPENTY) PHOSPHINIC ACID

The extraction of Cd(II), Cu(II) and Zn(II) from 0.1 mol dm^minus3 aqueous nitrate solutions with bis(2,4,4-trimethylpentyl)phosphinic acid (HBTMPP) dissolved in Isopar-H has been studied with relation to the total extractant concentration, the equilibrium pH and the total metal concentration in the aqueous phase.

The stoichiometry of the extracted species and their equilibrium constants have been determined by graphical and numerical methods and appear to be CdA₂ (HA)₂ and CdA₂ (HA)₃ for Cd(II), CuA₂(HA)₂ for Cu(II) and ZnAzHA and ZnAz(HA)₂ for Zn(II). The extraction efficiency follows the order Zn(II)<Cu(II)<Cd(II)     

COBALT-NICKEL SEPARATION BY SOLVENT EXTRACTION WITH BIS(2,4,4 TRIMETHYLPENTYL)PHOSPHINIC ACID

Abstract

The use of an organophosphinic acid to separate cobalt from nickel by solvent extraction is described. Comparative data indicate that the phosphinic acid is superior to analagous phosphoric and phosphonic acids in terms of cobalt-nickel selectivity and the ability to reject calcium. Important reagent properties, such as low aqueous solubility and hydrolytic stability, are discussed. The results of continuous, counter-current, mini-plant tests demonstrate the recovery of high purity cobalt from concentrated nickel sulphate solutions.     

二(2-乙基己基)磷酸萃取L-色氨酸

以二 (2 -乙基己基 )磷酸 (D2EHPA) -正辛烷 (体系A)及D2EHPA -正辛醇 +正辛烷 (体系B)萃取L -色氨酸为对象 ,研究了D2EHPA浓度、L -色氨酸初始浓度、稀释剂组成以及pH值对萃取平衡分配系数的影响 .结果表明 ,在实验研究涉及的pH值 (1.0     

二(2-乙基己基)磷酸萃取L-苯丙氨酸

以二（2-乙基己基）磷酸（D2EHPA）-正辛烷萃取L-苯丙氨酸为对象,研究了D2EHPA浓度、L-苯丙氨酸初始浓度以及pH值对萃取平衡分配系数的影响。不同pH值下负载有机相的红外谱图分析表明,D2EHPA与L-苯丙氨酸形成的萃合物结构与pH值无关。提出了在萃取过程中同时存在着离子交换反应和质子转移反应的观点。1个氨基酸分子与2个二（2-乙基己基）磷酸二聚体相结合。本文建立的萃取平衡分配系数关联式,拟合精度令人满意。     

THE EQUILIBRIUM REACTION OF THE EXTRACTION OF URANIUM(VI) WITH DI-(2-ETHYLHEXYL) PHOSPHORIC ACID FROM NITRIC ACID SOLUTIONS

The equilibrium reactions for the extraction of uranium(VI) with di(2-ethylhexyl)phosphoric acid from nitric acid solutions is investigated. In this work, proton NMR technique was used to verify that the nitrate ligand in the resulting complexes originated from the complexing of nitric acid. Organic solutions of 0.05 M (dimeric HDEHP, the upper bar denotes the species in the organic phase) in kerosene were used to extract aqueous solutions containing various concentrations of uranyl nitrate and nitric acid. The concentrations of nitric acid and uranium(VI) in the organic phase were measured, and used to determine the composition of the resulting complex. Which were found to be varied with the uranium(VI) loading and the nitric acid loading of HDEHP. Parallel reactions of forming UO were proposed to describe this extraction system. The proposed reactions elucidate the equilibrium behavior consistently, for the loadings of uranium(VI) and nitric acid ranging from very low value to the vicinity of saturation.     

STUDY OF MICELLAR EXTRACTION IN THE SYSTEM (2-ETHYLHEXYL) PHOSPHONIC ACID MONO-(2-ETHYLHEXYL) ESTER - Co (II) - SURFACTANT

ABSTRACT

The equilibrium and kinetics of the extraction of cobalt (II) by P507 in Teric N9 micelles have been studied. The structure of the (2-ethylhexyl) phosphonic acid mono-(2-ethylhexyl) ester (known as P507), in Teric N9 micelles have been investigated using interfacial tension and fluorescence quenching measurements. It has been found that there is an interaction between these two components and mixed micelles are formed

The complex of Co²⁺ with P507 in Teric N9 aqueous solution has been shown to have a 1:3 stoichiometry and the equilibrium constant has been obtained by slope analysis. The rate of complex formation in the micelle media is very fast with the reaction going to completion in less than 0.2 seconds.     

EXTRACTION OF PHOSPHORIC ACID FROM NITRATE SOLUTIONS WITH ISOAMYL ALCOHOL

The extraction of phosphoric acid with isoamyl alcohol from aqueous solutions relevant to and produced by leaching of phosphatic iron ore by nitric acid has been studied. The results indicate that the extraction of phosphoric acid is not temperature dependent in the range 25–40°C, and that it increases with increasing the concentration of HNO₃ or H₂SO₄. The salting-out effect of the different nitrate salts on the extraction of phosphoric acid is found to be in the order of Mg²⁺> Ca²⁺ > Na+> NH+₄ K+. The presence of Fe³⁺ and Al³⁺ may reduce the extraction of phosphoric acid. Phosphoric acid can be extracted selectively against the different nitrate salts but nitric acid is coextracted. The excess coextraction of nitric acid from the aqueous phase will result in the precipitation of some phosphate complexes of Fe, Al, Ca, etc. Some tests of the continuous multistage extraction were also performed and a flowsheet for the recovery of the phosphoric acid is suggested.     

EXTRACTION OF RARE EARTH METALS WITH 2-ETHYLHEXYL PHOSPHONIC ACID MONO-2-ETHYLHEXYL ESTER IN THE PRESENCE OF DIETHYLENETRIAMINEPENTAACETIC ACID IN AQUEOUS PHASE

Abstract

The extraction equilibria of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (commercial name, PC-88A, henceforth abbreviated as HR) dissolved in n-heptane were measured at 303 K. It was found that rare earth metals are extracted with the dimer of the extractant, (HR)₂, as follows.

The extraction equilibrium constants of metals were obtained and compared with the extraction equilibrium constants obtained by di(2-ethylhexyl)phosphoric acid (henceforth D2EHPA).

Furthermore, the extraction equilibria of rare earth metals with PC-88A in the presence of diethylenetriaminepentaacetic acid (henceforth DTPA) in an aqueous phase were also measured to discuss the effect of DTPA on the extraction of rare earth metals.     

SOLVENT EXTRACTION OF URANIUM( VI) AND THORIUM( IV) FROM NITRATE MEDIA BY CARBOXYLIC ACID AMIDES

ABSTRACT

A series of nineteen N-alkyl carboxylic acid amides (R.CO.NHR') has been prepared, in which the alkyl groups R and R' have been varied in order to introduce different degrees of steric complexity into the compounds. A smaller number of N,N-dialkyl amides (R.CO.NR₂) and non-substituted amides (R.CO.NH₂) has also been prepared for comparison purposes. These amides were characterized by measurement of their boiling points, melting points, refractive indices and densities.|The solvent extraction of uranium(VI) and thorium(IV) from sodium nitrate media by solutions of the amides in toluene was studied. Increasing steric bulk of the alkyl groups R and R' was found to cause a marked decrease in the extraction of thorium, with a much smaller effect on the extraction of uranium, thus considerably enhancing the separation between these metals. Vapour pressure osmometry studies indicate that the N,N-alkyl amides are self-associated in toluene solution, with aggregation numbers up to about 2.5 for 0.6 M solutions at 35°C. In contrast, the N,N-dialkylamides behave as monomers under these conditions. The distribution ratios for the extraction of uranium and thorium show second- and third-order dependences, respectively, on the extractant concentration for both the N-alkyl and N,N-dialkyl amides.     

THE EFFECT OF TRIOCTYLPHOSPHINE OXIDE ON PHASE AND EXTRACTION EQUILIBRIA IN SYSTEMS CONTAINING BIS( 2,4,4-TRIMETHYLPENTYL) PHOSPHINIC ACID

The metal extractant Cyanex© 272 contains bis(2,4,4-trimethylpentyl)-phosphinic acid (BTMPPA) as the main component and trioctylphosphine oxide as an impurity. As-received Cyanex 272 and pure BTMPPA were observed to significantly differ in respect to both their phase behavior during saponification and to their copper extraction ability. The differences were elucidated by investigating the effects of an addition of small amounts of tri(n-octyl)phosphine oxide (TOPO) on the phase equilibria in the system Water(2.4M NaOH)/BTMPPA/n-Hexane at 25?°C as well as in the system Water(2.4M NaOH)/BTMPPA at various temperatures. In the absence of TOPO a large microemulsion region and a small region of lyotropic liquid crystalline phase with lamellar structure are formed. When TOPO is added into the system the lamellar phase gradually disappears. The effects of TOPO on metal extraction equilibria were studied by measuring the distribution of copper(II) between a perchloric acid solution and a BTMPPA in chloroform solution in the presence and absence of tri(n-octyl)phosphine oxide.     

GLYCINE ENHANCED SEPARATION OF Co(II) AND Ni(II) WITH BIS(2,4,4-TRIMETHYLPENTYL)PHOSPHINIC ACID [CYANEX 272] BY LIQUID-LIQUID EXTRACTION AND SUPPORTED LIQUID MEMBRANES

ABSTRACT

The extraction behavior of Co and Ni ions from aqueous nitrate solution containing glycine, and their separation by liquid-liquid extraction and supported liquid membranes (SLMs) has been studied. The separation factor between the two metals is greatly enhanced by the presence of glycine. The enhancement is due to the preferential complexation of the Ni ions by glycine. The conditional equilibrium constants of the extraction reactions and the SLM permeability coefficients have been measured. The results indicate that metal glycinate complexes are not extracted and that in presence of glycine very clean Co-Ni separation can be obtained in a single SLM pass.     

EXTRACTION STUDIES ON THE SYSTEM BETWEEN BIS(2-ETHYLHEXYL) PHOSPHORIC ACID AND CHROMIUM(III) IN SEVERAL AQUEOUS SOLUTIONS

The extraction of chromium(III) by carboxylic acids and acidic organophosphorus compounds has been investigated. In general, chromium(III) was not extracted by carboxylic acids but the organophosphorus compound, di-2-ethylhexyl phosphoric acid, was found to be particularly adequate for the extraction. The partition of chromium(III) in nitrate medium and solutions of di-2-ethylhexyl phosphoric acid in Shellsol-T was studied using a tracer of 51cr. Distribution measurements of the metal ion in a wide range of pH and organophosphoric acid concentrations have been performed. The experimental data treated by a graphical method have been explained assuming the presence in the organic phase of the species Cr(DEHP)₃(H₂O)²(HDEHP). Equilibrium constants for the different extraction reactions are given. The extraction of the monomeric species was found to be independent of Ac^?or SO⁼ ₄ions presence.     

EXTRACTION KINETICS OF COPPER BY TRILAURYLAMMONIUM CHLORIDE IN TOLUENE FROM AQUEOUS CHLORIDE MEDIA

Abstract

The rate of extraction of copper(II) from aqueous chloride solutions by tri-n-laurylammonium chloride (TLAHC1) dissolved in toluene has been investigated. The extraction rate was evaluated as function of the chemical composition of the system. The experiments were performed by using a stirred cell with constant inter-facial area. The experiments were performed at a stirring rate of the two phases where the influence of film diffusion is minimized. The data have been interpreted by a mechanism which assumes interfacial chemical reactions between the bulk species containing copper(II) and the molecules of TLAHC1 absorbed at the interface as rate determining.     

EXTRACTION OF NICKEL FROM AQUEOUS SULFATE SOLUTION INTO BIS(2,2,4-TRIMETHYLPENTYL)PHOSPHINIC ACID,CYANEX 272TM -EQUILIBRIUM AND KINETIC STUDIES

ABSTRACT

Equilibrium and kinetic studies have been carried out on the extraction of nickel from sulfate solutions using bis(2,2,4 trimethylpentyl) phosphinic acid HDTMPP, “Cyanex 272tm”- It was found that nickel extraction in HDTMPP was favored by the presence of sodium in the organic phase and that equilibrium nickel concentration could be written in terms of the pre-equilibrated extractant concentration

Kinetic studies were carried out using the rising drop method, reaction orders were determined with respect to the aqueous phase nickel concentration, Ni²⁺, the aqueous phase sodium concentration, Na ⁺ the pH, the organic phase dimer concentration ------ and the organic phase sodium salt concentration ---- In addition, it was found that the extraction kinetics could be explained in terms of an aqueous phase interfacial reaction accompanied by diffusion through the interface. Mass transfer coefficient values were determined indicating extraction rates for metal extraction into HDTMPP were the same order of magnitude as those found for HDEHP.     

EXTRACTION OF LANTHANIDE METALS WITH B.TS (2. 4, 4-TRIMETHYLPENTYL) PHOSPHINIC ACID

Extraction equilibria for a series of lanthanide ions using chloroform solutions of bjs(2, 4, 4-triraeth-ylpentyl)-phosphinic acid (HBTMPP), either alone or combined with adduct forming agents have been studied. The extracted species are Ln (HTMPP) (HBTMPP), and. Ln(BTMPP)₃ (HBTMPP)(TOPO) in the presence of trioctyl-phosphine oxide (TOPO). TOPO war; found to increase both the extractability and selectivity of lanthanide metals in the system.     

SOLVENT EXTRACTION OF LEAD BY TRILAURYLAMMONIUM CHLORIDE DISSOLVED IN TOLUENE FROM DIFFERENT CHLORIDE MEDIA

The extraction of Pb(II) from chloride solutions by trilaurylammonium chloride (TLAHC1) dissolved in toluene has been studied by metal distribution measurements. The work has been performed at three different aqueous chloride concentrations (1.0, 2.0 and 3.0 mol.dm^?3NaCl). The treatment of the experimental data at each chloride concentration agrees with the stoichiometry of the extracted metal species in the organic phase while the values of their equilibrium constants are different for the various chloride concentrations. The extraction process is explained by the following extraction reactions

The corresponding logarithmic values of K₂and K₅at the different chloride concentrations, I, are: K₂K₅, I; 4.62, 8,51, 1.0; 4.54, 8.38, 2.0; 4.48, 8.32, 3.0. The values obtained have been correlated by using the Specific Interaction Theory (S.I.T.) and the interaction coefficient for the Pb²⁺,Cl^?ions as well as the thermodynamic constants, Kn⁰, have been determined.     

EXTRACTION OF Ni(It) BY DI-(2-ETHYLHEXlfL)PHUSPHOKIC ACID DISSOLVED IN TOLUENE

ABSTRACT

The extraction of Ni(II) from 1.0 mol-dm^-3aqueous NaNO₃medium by di-(2-ethylhexyl) phosphoric acid (HDEHP) dissolved in toluene has been studieo as a function of the total extractant concentration, the equilibrium pH and the total raetal concentration in the aqueous phase. Nickel distribution data have been interpreted in terms of the formation of NiR₂(HR)₂, and NiR₂species in the organic phase in the low pH range anc by the formation of Na-HUEHP micelles, due to the neutralization of the reagent in the organic phase, and the further exchange of Na⁺by Ni²⁺in these micelles in the high pH range for each of the total extractant concentrations used.