The use of14C,59Fe and65Ni radionuclides for the study of solvent effects on the extraction equilibria with n-caprylic acid

The distribution of n-caprylic acid between an aqueous sodium sulphate solution and several organic diluents of various properties has been investigated, using¹⁴C-labelled n-caprylic acid. The distribution coefficients of the monomeric capyrlic acid and its dimerization constants in the organic phase were determined. The extraction of Fe(III) and Ni(II) with n-caprylic acid solutions in various diluents was studied using the AKUFVE solvent extraction equipment. The composition of the extracted compound of Fe(III) has been determined and the extraction constants for all the studied systems have been calculated. For the extraction of Ni(II) the constants of the extraction of nickel caprylate monomers and its dimerization constants in the organic phase have been calculated.     

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.     

Investigation of the extraction equilibrium of ion-association complexes of molybdenum (VI) with some polyphenols and thiazolyl blue. extraction-spectrophotometric determination of molybdenum

The extraction process of ternary ion-association complexes of molybdenum (VI) with some polyphenols (4-nitrocatechol, 2,3-dihydroxy naphthalene) and thiazolyl blue has been investigated by using an extraction-spectrophotometric method. The optimum conditions for their quantitative preparation in aqueous medium and subsequent extraction into an organic solvent have been found. The extraction, distribution and association constants, and the recovery factors have been calculated. The composition of the complexes has been determined. A precise, sensitive and simple extraction-spectrophotometric method for determination of molybdenum in products from ferrous metallurgy has been developed.     

Investigations of the extraction equilibrium of ternary ion-association complexes of thallium(III) with ditetrazolium salts,neo-tetrazolium chloride and nitrobluetetrazolium chloride

The extraction equilibrium of ternary ion-association complexes formed between the tetrachloro complexes of thallium(III) and ditetrazolium salts, neotetrazolium chloride (NTC)[2,2′,5,5′-tetraphenyl-3-3′-(p-biphenylene)ditetrazolium chloride] and nitrobluetetrazolium chloride (NBT)[3,3′-dianizole-4,4′-bis-2-(4-nitrophenyl-5-phenyltetrazolium chloride], has been studied. As a result, the extraction constants, the distribution constants, the association constants, the distribution coefficients of thallium(III) and the extraction indicators R, have been calculated. The results have been evaluated statistically. The relative standard deviations S_r have been calculated at a statistical certainty of 95%. The ratio ditetrazolium salts/TlCl ₄ ⁻ =1∶2 has been confirmed once again.     

银离子配位萃取银杏叶中多萜长链化合物的研究

本文建立了银杏叶中多萜长链化合物Ag⁺配位萃取方法，构筑了含Ag⁺配位萃取体系。研究了萃取剂极性、萃取温度、Ag⁺浓度等因素对分配比D的影响，分析测定了银杏叶聚戊烯醇(PPs)与Ag⁺的配位萃取比m，确定了配位萃取条件及解离条件。试验结果表明，所建立的含Ag+配位萃取剂用于分离浓缩聚戊烯类化合物选择性好、效率高，萃取剂再生方法简便。     

Liquid-liquid extraction and reversed phase chromatographic behaviour of some 3d metal ions using bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301)

Studies have been carried out on the extraction behavior of some metal ions of the first transition series using bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301) from mineral acid media. The effect of various parameters influencing the extraction such as the nature of the diluent, concentration of the acid and the extractant on the distribution has been investigated. Based on the distribution data some binary separations have been proposed. A flow sheet of a scheme is given for the recovery of manganese free cobalt from a spent catalyst used in the manufacture of poly(ethyleneterepthalate).     

Investigation of the extraction equilibria in the system hexachloridorhenate(IV)-neotetrazolium chloride-dichloroethane-water

The neotetrazolium hexachloridorhenate(IV) (NTReCl(6)) has been synthesized and its composition checked. The optimum conditions for the extraction of NTReCl(6) with dichloroethane have been established. The recovery factor for one-fold extraction is R = 74%. The distribution constant, K(D), extraction constant, K(ex), and ion-association constant, beta, have been determined. Neotetrazolium chloride was found to be suitable reagent for extraction-spectrophotometric determination of rhenium(IV) ((NTReCl(6)) = 3.42 +/- 0.20 x 10(4)M(-1) cm(-1)).     

Equilibrium and kinetics of Zn(II) bromide extraction with Amberlite LA-2 and methyl isobutyl ketone

The rates of extraction of Zn(II) from hydrobromic acid solutions into benzene solutions of the liquid anion exchanger Amberlite LA-2 and those into methyl isobutyl ketone (MIBK) have been investigated. The distribution equilibria of this system have been also studied. Under the used experimental conditions the extracted species of Zn(II) have been proposed. The kinetic data indicated a first order reaction with respect to Zn(II) in both systems, nearly one with respect to HBr and from 0–0.38 for LA-2. In case of extraction of Zn(II) with methyl isobutyl ketone, MIBK, the reaction order with respect to MIBK was found to be 4 and with respect to HBr inverse first order. The rate constants of these extraction processes were determined and the rate determining steps were discussed in the light of the obtained results.     

Extraction of Zr(IV) by TBP-DMSO and TBP-Py from aqueous solutions containing monobasic acids

The distribution ratios for the extraction of Zr(IV) by TBP and its binary mixtures with DMSO or Py in n-dodecane in the presence of HNO₃, and HClO₄ have been determined. Based on stoichiometric and slope analysis methods a possible mechanism for the extraction has been proposed.     

Extraction of Fe(III) by n-dodecanoic acid dissolved in toluene

The extraction of Fe(III) from a nitrate medium of ionic strength 1.0 mol dm⁻³ by n-dodecanoic acid (HA) dissolved in toluene has been studied by distribution measurements. Experimental data, treated by different graphical and numerical methods, have been explained assuming the extraction of the species (FeA₃)₃ into the organic phase as well as the formation of a Fe(III)-HA complex in the aqueous phase.     

Extraction of cadmium(II) by organophosphorus compounds

The extraction of cadmium(II) by di-(2-ethylhexyl) phosphoric acid dissolved in tetradecane from aqueous chloride and perchlorate solutions has been studied at 25°C. The distribution of the metal has been determined as a function of metal and DEHPA concentrations. Distribution data have been treated both graphically and numerically using the program LETAGROP-DISTR (Acta Chem. Scand. 1971, 25, 1521) and the composition of the extracted species into the organic phase has been determined. The extraction constants for these species are given in Table 1.     

苯甲酸稀溶液的萃取特性

磷酸三丁酯;正辛醇;苯甲酸稀溶液的萃取特性     

Studies on extraction of thorium by the N-oxides of 5-(4-pyridyl)nonane and trioctylamine from different mineral acid solutions and its separation from rare earth elements and yttrium

The N-oxides of 5-(4-pyridyl)nonane and trioctylamine have been evaluated for use in the extraction of thorium from different mineral acid solutions. The influence of the concentration of the solvents and salting-out agents has been investigated. The possible mechanism of extraction is discussed in the light of the results of extraction isotherms, loading-ratio data and log-log plots of reagent concentration vs. distribution ratio. Separation factors for a number of metal ions are reported and a method for the separation of thorium from rare earth elements and yttrium is also suggested.     

Stability and distribution constants of thallium(I) xanthates

Stability and distribution constants of thallium(I) ethyl, n-propyl, isopropyl, n-butyl, isobutyl and sec-butyl xanthates have been radiometrically determined using ion-exchange and extraction methods. The length of the alkyl chain influences the distribution constant, however, it has only a small effect on the stability constant.     

Selective extraction of Hg(II) from aqueous mineral acid solution containing iodide ions using 2-benzylpyridine in benzene

A method for the selective extraction of mercury has been developed. The extraction of Hg(II) by 2-benzylpyridine (BPy) in benzene from dilute mineral acid solution containing iodide ions has been investigated, and variables such as concentration of acids, iodide and the extractant have been optimized. The optimum conditions for the extraction of Hg(II) by 0.1M BPy/benzene are: 0.01M (HCl, HNO₃, H₂SO₄)+0.01M KI. The distribution coefficients and separation factors of 19 elements relative to Hg(II), have been reported. Effect of anions such as ascorbate, acetate, citrate, oxalate and thiosulfate has also been studied. The method developed could find useful applications in selective extraction of small amounts of mercury from environmental samples.     

Extraction of uranium(VI) and thorium(IV) ions from nitric acid solutions by N,N,N′,N′-tetrabutyladipicamide

A new symmetrical diamide, the straight-chain alakyl substituted neutral tetrabutyladipicamide (TBAA) has been synthesized, characterized and used for the extraction of U(V) and Th(IV) from nitric acid solutions in a diluent composed of 50% 1,2,4-trimethylbenzene (TMB) and 50% kerosene (OK). Extraction distribution coefficients of U(VI) and Th(IV) as a function of aqueous nitric acid concentration, extractant concentration and temperature have been studied. Back-extraction of U(VI) and Th(IV) from organic phases by dilute nitric acid has been undertaken. From the data, the compositions of extracted species, equilibrium constants and enthalpies of extraction reactions have also been calculated.     

Solvent extraction study of cobalt(II) with 8-mercaptoquinoline

Equilibrium distribution coefficients have been determined for the extraction of cobalt(II) with 8-mercaptoquinoline as a function of pH and reagent concentraton at ambient temperature. The extractable complex is a diadduct, i. e. two molecules of the reagent are coordinated to the cobalt(II) chelate. The adduct formation constant in chloroform and the overall formation constant in the aqueous phase have been determined. Pyridine and its methyl derivatives were found to enhance the extraction of Co(II) into chloroform in the presence of 8-mercaptoquinoline. From the extraction equilibrium data, the adduct formation constants of 12 chelate to nitrogen base adducts were evaluated. The special role of steric factors is discussed.     

Solvent extraction of heptavalent technetium

An extraction study was performed on technetium in its highest oxidation state as a function of nitric acid concentration at 25, 50 and 70 °C. A long chain amine (tri-n-octylamine TOA) and an organophosphorus solvent (TBP) have been investigated. Addition of NH₄NO₃ has a salting-out effect on the extraction of TBP in the aqueous phase and therefore decreases the distribution coefficient for heptavalent technetium. The mechanism of extraction is discussed in the light of the results obtained.     

Studies on Liquid‐Liquid Extraction and Recovery of Bismuth(III) from Succinate Media Using 2‐Octylaminopyridine in Chloroform

A procedure is described for the liquid‐liquid extraction and recovery of bismuth(III) from succinate solution using 2‐octylaminopyridine (2‐OAP) as an extractant. The quantitative extraction of bismuth(III) occurs from 0.004 to 0.007 M sodium succinate solution of pH 2.5‐10 using 0.036 M 2‐OAP in chloroform. The extracted metal ion has been recovered by stripping with (3 × 10 mL) 0.5 M nitric acid. The log‐log plot of distribution ratio versus succinate concentration and distribution ratio versus 2‐OAP concentration gave slopes of 2.0 and 0.9, respectively, indicating a metal‐succinate ratio of 1:2 and a metal: 2‐OAP ratio of 1:1. The ion pair complex has a high distribution ratio in chloroform, while other solvents are poor. The extractants are stable towards prolonged acid contacts and there is no loss in its extraction efficiency even after recycling ten times. The extraction behaviour of some commonly associated metal ions, namely Ga(III), Cd(II), Zn(II), Cr(VI), Cu(II), Ba(II), Sb(III), Sn(IV), Tl(I) and Pb(II), has also been investigated. Based on partition data, conditions have been identified for attaining some separations of bismuth(III) from other metal ions; these conditions are extended for the recovery of pure bismuth from ore and alloys. Thermodynamic quantities for the extraction process were calculated.     

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.