THE SEPARATION OF NEPTUNIUM AND PLUTONIUM FROM NITRIC ACID USING n-OCTYL(PHENYL)-N,N DIISOBUTYLCARBAMOYLMETHYLPHOSPHINE OXIDE EXTRACTION AND SELECTIVE STRIPPING†

The extraction of neptunium and plutonium in several oxidation states was studied as a function of nitric acid concentration for 0.1M n-octyl(phenyl)-N, N-diisobutylcarbamoyl -methylphosphine oxide in 1.4M tributylphosphate with dodecane diluent. Np(V) is only weakly extractable over the range of acid concentrations studied while Np(IV) and Np(VI) are highly extractable. Pu(IV) and Pu(VI) are also highly extractable while Pu(III) was extracted but with lower efficiency. An Fe(II) reductant was used to reduce neptunium to Np(IV) and plutonium to Pu(III) for the initial extraction. Pu(III) was then stripped with dilute HNO₃ in the presence of a holding reductant leaving the Np(IV) in the organic phase. Neptunium may then be recovered to an aqueous phase with one of a number of complexing agents.     

EXTRACTION OF AMERICIUM(III) FROM CHLORIDE MEDIA BY OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYLPHOSPHINE OXIDE∗

The extraction of Am(III) from chloride media was studied using octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide, Oπ D(iB)CMPO or CMPO, dissolved in tetrachloroethylene. Although the extraction of Am(III) by 0πD(iB)CMPO is many orders of magnitude weaker from chloride than nitrate media, the rapid Increase in the mean activity of chloride in HC1 and in most soluble chloride salts with concentration makes extraction from moderate to concentrated hydrochloric acid and/or concentrated Li, Mg, Ca, and Al chloride salt solutions practical. The stoichiometry of the extractable chloro complex was established by extractant dependency and loading experiments and found to be AmCl₃»3CMPO. Hydrochloric acid appears to be associated with the complex when extraction takes place at high HC1 concentrations. The mode of coordination of OπD(iB)CMPO to AmCl₃appears to be bidentate in marked constrast to its behavior in the corresponding nitrate system.     

EXTRACTION OF PLUTONIUM BY CHELATING HYDROXYPYRIDINONE AND CATECHOLAMIDE RESINS∗

ABSTRACT

Four new chelating hydroxypyridinone and catecholamide polystyrene-supported extractants have been prepared and evaluated for their ability to selectively remove ppm levels of plutonium from a variety of acidic aqueous waste compositions. The hydroxypyridinone and catecholamide ligands, modeled after the metal ion binding sites found in siderophores, were derivatized to allow covalent attachment to a polymeric support. The synthesis, loading capacities and chemical stability of the new resins are reported along with the results from extraction studies evaluating their performance for the extraction of Pu(IV) and Pu(VI) from a variety of HNO₃ and NaN0₃ solutions up to 5 M and in competition with Fe(III), Al(III), Zr(IV) and EDTA. The kinetics of metal ion sorption onto the resins are fast, and the extraction results are compared to the commercial Chelex resin.     

ZIRCONIUM EXTRACTION INTO OCTYL(PHENYL)-N,N- DIISOBUTYLCARBAMOYLMETHYL PHOSPHINE OXIDE AND TRIBUTYL PHOSPHATE†

ABSTRACT

Classical slope analysis techniques were used to determine the octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) and nitrate stoichiometrics for the extraction of zirconium by CMPO diluted with diisopropylbenzene (DIPB). The equilibrium constant for the extraction of zirconium by CMPO was also determined using classical slope analysis techniques. The extraction of zirconium by TBP in n-dodecane was used as a control to verify the zirconium species as Zr⁺⁴, and to verify the experimental methodology. Equilibrium [CMPO]_org and [TBP]_org concentrations were determined by accounting for the extraction of HNO₃ into both TBP and CMPO solvents. Nitric acid dissociation and aqueous phase activity coefficients were also taken into consideration. Organic activity coefficients, Zr⁺⁴ activity coefficients, Zr⁺⁴ hydrolysis, and consumption of TBP or CMPO by water were neglected. Nitrate and CMPO dependencies for the extraction of zirconium have been determined from this work to be:

An equilibrium constant of 1.13 × 10⁵ ± 1.48 × 10⁴ at 25^° C was also determined for this reaction.     

PERIODIC VARIATIONS OF LANTHANIDES YKERGIC EXTRACTION BY THENOYLTRI-FLUOROACETONE AND TRIPHENYLPHOSPHINE OXIDE MIXTURE∗

Abstract

The synergic extraction of the different lanthani-des, except Pm and Lu, by thenoyltrifluoroacetone (HTTA) and triphenylphosphine oxide (TPPO) mixture in benzene from an aqueous perchlorate medium of constant ionic strength of 0·2 was investigated. It was found that the main adduct extracted contains the lanthanide chelates together with two TPPO molecules. The different extraction and formation constants for the lanthanides investigated have been determined. The variations of the logarithmic values of the chelate extraction constant and the adduct formation constant with the different lanthanides was discussed in the light of the tetrad and the inclined-W effects. The experimental results showed that the nature of coordination by adduct formation for the Yb-Sm group is different than that of the Pr-La group.     

SYNERGISM IN THE EXTRACTION OF ZINC(II)AND CADMIUM(II) WITH SOME LOWER FATTY ACIDS IN THE PRESENCE OF AMINES AND THEIR SEPARATIONS∗

Abstract

Synergism in the extraction of Zn(Il) and Cd(II)with chloroform solution of propionic, butyric and valeric acids in the presence of n-butylamine, dibutylamine, tributylamine, β-picoline, pyridine and quinoline is reported The effect of various parameters affecting extractions has been investigated The compositions of synergistic adduct extracted into the organic phase have been proposed on the basis of slope analysis method. In general the species have been represented as MA2.2HA.B (aliphatic amine system and MA₂.2HA.2B (heterocyclic amine system), where M = zn(Il)/CdII), HA = acid and B = amine. On the basis of extraction constant (K_ex) values the relative effectiveness of different amines as synergists has been compared. Based on the extraction data some separations of metal ions have also been reported with fairly high separation factor (β).     

SOLVENT EXTRACTION OF Au(III), Pd(II) AND Pt(lV) WITH SULFUR-CONTAINING METHYLPHOSPHONATES AND β-KETOPHOSPHONATE

Three sulfur-containing methylphosphonates, dibutyl propylthiomethylphosphonate, (C₄H₈O)₂P(0)CH₂SC₃H₇,(DBPTMP),dibutyl propylsulfinylmethylphosphonate, (C₄H₉0)₂P(0)CH₂S(0)C₃H₇, (DBPSiMP) and dibutyl propylsulf onylmethylphosphonate, (C₄H₈O)₂P(0)CH₂S(0) C₃H₇ (DBPSiMP) were synthesized. The extraction of gold(III), palladium(II) and platinum(IV) from HCl media with the synthesized compounds and dibutyl 2-keto-3-methylbutyl-phosphonate, (C₄H₈O)₂P(0)CH₂C (0) CH(CH₃) CH₃, (DBKPP) was investigated at various mixing times and acidities. DBPTMP and DBPSiMP were found to provide nearly quantitative extraction of Au(III) and Pd(II) with short equilibration times for Pd(II) extraction. DBKPP was selective for Au(TII) over Pt(IV) and Pd(II) at high acidity. The behavior of these extractants was also examined in comparison with the corresponding monofunctional extractants, dibutyl butylphosphonate(DB‘BP’), tributyl-phosphate(TBP), dioctylsulphide(DOS) and dioctyl-sulphoxide(DOSO).     

STUDIES ON EXTRACTION AND COORDINATION OF RARE EARTHS WITH β-KETOPHOSPHONATES

The rare earth extraction and coordination by three β-ke-tophosphonates with various structure, dibutyl 2-keto-2-phenyl-ethylphosphonate, (C₄H₉O)₂P(O)CH₂C(O)C₆H₅, (I), dibutyl 2-keto-pentylphosphonate, (C₄H₉O)₂P(O)CH₂C(O)C₃H₇, (II) and dibutyl 2-keto-3-methylbutylphosphonate, (C₄H₉O)₂P(O)CH₂C(O)CH(CH₃)CH₃, (III) from nitric acid medium have been described in this paper. The regularity of rare earth extraction with these β-ketophos-phonate reveals the same manner and resembles that of the common extractant, tributylphosphate (TBP). The extracted species has been deduced as Nd(NO₃)₃.3L and HNO₃-L by the slope method. By investigating the shift of P=0 and C=0 in IR spectra of the coordination compound prepared by saturated method, the predomination of P=0 has been established which coincides with the estimation from their extraction behavior.     

A NEW ARRANGEMENT OF EXTRACTION CASCADE——MULTIPLE STAGE COUNTER-CURRENT EXTRACTION PROCESS WITH ALTERNATING EXTRACTION AND STRIPPING

In this article a new arrangement of extraction cascade—multiple stage counter-current extraction processwith alternating extraction and stripping is presented.The effects of increasing mass-transfer rate and decreas-ing the number of extraction stage in an extraction process may be obtained by adopting this new arrange-ment.Extraction cascade calculation for two extraction systems-extraction of iron with N,N-bis-(l-methl-heptyl)acetyl amide(N-503)* and extraction of H_3PO_4 with DBSO has been carried out and the experi-ment has been done with the former system.The results of calculation and experiment show that the extraction efficiency increases significantly byadopting this new alternating arrangement,compared with a commun multiple stage counter-current process.The new alternating extraction and stripping arrangement may be called alternating extraction process.     

STUDIES ON ULTRASONIC DEGRADATION AND BLOCK COPOLYMERIZATION OF POLYACRYLAMIDE AND POLY(ETHYLENE OXIDE)

The kinetics of ultrasonic degradation of aqueous solution of polyacrylamide(PAM)and poly(ethyleneoxide)(PEO)as well as ultrasonic block copolymerization of aqueous solution of the mixture of PAM/PEOwere studied respectively.The degradation reaction of PEO follows a linear relationship between(P_1-P_∞)~(-1)and irradiation time,while that of PAM follows a linear relationship between(P_1-P_∞)~(-1/2)and irradiation time.The structure of the copolymer was identified by IR,NMR and DTA,and the copolymer prepared is a blockone.The copolymer formed by irradiating 1% aqueous solution of PEO/PAM mixture(1:1)for a period of40min.at 18.2 kHz with a sonic intensity corresponding to 2.OA input current on the reversed main circuitamounts to 61.8%.     

KINETICS OF THE EXTRACTION OF COBALT WITH EXTRACTANT P5709

The kinetics of extraction of cobalt with P5709 was studied in a Lewis cell. In the extraction system the aqueous phase was the solution of CoSO_4 (8.8×10~(-4)—3.4×10~(-2)M) and Na_2SO_4 (0.63M.) at pH 5.5; the organic phase was 15% (v/v) P5709 in kerosene (saturated with hydrogen).In order to determine the control regime of extraction of cobalt, the stirring speed, the interracial area between the two phases and the operating temperature were varied in the experiments. Experimental results showed that the extraction process of cobalt was predominantly governed by the diffusion process, and the overall mass transfer coefficients were found to be as follows:_((a)): (2-5)×10~(-3)cm/s, _((o)): (0.3-1)×10~(-3)cm/s.The results of the experiments and calculations indicated that K did not remain constant during the extraction process, Reasons for the variations in K were discussed.     

LIQUID-LIQUID EXTRACTION OF Pa(V) AND Zr(IV) BY MIXTURES OF A β-DIKETOHE AND A SULPHOXIDE FROM HTDROCHLORIC ACID MEDIA

The species involved in the solvent extraction of zirconium(IV) from hydrochloric acid medium by mixtures of thenoyltrifluoroacetone (HTTA) and dipentyl sulphoxlde (DPSO) in benzene as the diluent seems to be Zr(OH) ₂(TTA)₂(DPSO). Extraction of protactinium(V) by mixtures of HTTA and DPSO exhibits synergism but the extent of synergism is not very appreciable.     

RATE OF COPPER EXTRACTION AND INTERFACUL ACTIVITY OF MODEL β-DHCETONES

ABSTRACT

Interfacial tension isotherms and rate of copper extraction were studied for model β-diketones of LIX 54 and of pyrazolone type. The effect of the position and structure of the hydrophobic alky1 group upon interfacial activity and rate of extraction is discussed. The preadsorption of extractant molecules at the water/hydrocarbon interface is not needed to obtain a quick and effective extraction.     

THE EXTRACTION BEHAVIOR OF MOLYBDENUM USING DIHEXYL-N.N-DIETHYLCARBAMOYLMETHYLPHOSPHONATE∗

ABSTRACT

The extraction behavior of Mo from HNO³ was studied using dlhexyl-N,N-dlethylcarbamoylmethylphosphonate. Distribution coefficients were measured as a function of contact time, concentration of Mo, HNO₃, N0₃ and extractant, and extraction temperature. Above 11 M HNO₃, Mo is appreciably extracted.     

EXTRACTION OF SODIUM IN BIS (2, 4,4 - TRIMETHYLPENTYL) PHOSPHINIC ACID “CYANEX 272”TM BASIC CONSTANTS AND EXTRACTION EQUILIBRIA

A study has been made of the extraction of sodium into bis (2,4,4 -trimelhylpentyl) phosphinic acid. The following basic constants were measured at 25^°C using two-phase titration techniques: the solubility in water, S, the ionization constant, pKa the dimerization constant, K₂, and the distribution coefficient, Kd. The results were found to be in agreement with values reported in the literature for other phosphorus based extractants. A comparison was made with the data reported for sodium extraction iD phosphorous, phosphonic and phosphinic acid based ex-tractants. The data indicated that similar behaviour can be expected for all these compounds.     

COBALT–NICKEL SEPARATION: THE EXTRACTION OF COBALT(II) AND NICKEL(II) WITH BIS(2-ETHYLHEXYL) PHOSPHINIC ACID (PIA-8) IN TOLUENE

The extraction behaviour of cobalt(II) and nickel(II) from sulfate solutions with bis(2-ethylhexyl) phosphinic acid (PIA-8) in toluene has been studied. Quantitative extraction of Co(II) was observed at pH 5.0–5.9 while that of Ni(II) at pH 6.8–7.0 with 0.03 M PIA-8 in toluene. The difference in pH_0.5 for Co(II) and Ni(II) was 1.9. The stoichiometry of the extracted species were determined by slope analysis method. The extraction reaction proceeds by cation exchange mechanism and the extracted species were Co · R₂(HR)₂ and Ni · R₂ · 2(HR)₂. Temperature dependance of the extraction equilibrium constants were determined to estimate the apparent thermodynamic functions (ΔG, ΔS and ΔH). The method was used for separation of cobalt(II) and nickel(II). Cobalt(II) was separated from nickel even at 1:20 (Co:Ni) ratio. The separation of cobalt(II) from nickel(II) was favoured with the increase in temperature.     

AGGREGATION OF P,P' -DI( 2-ETHYLHEXYL) METHANEDIPHOSPHONIC ACID AND ITS Fe(III) COMPLEXES ∗

ABSTRACT

The aggregation of P,P' -di( 2-ethylhexyl) methanediphosphonic acid, H2DEH[ MDP] dissolved in deuterated toluene has been investigated by small angle neutron scattering ( SANS) The title compound was shown to exist in solution as a dimer under all conditions. Dimer formation is independent of the acidity of the aqueous solution with which the organic solution is pre-equilibrated. Solutions of H₂ DEH[ MDP] containing increasing amounts of Fe( lll) extracted from aqueous solutions in the acidity range from 0.1 to 5 M were also investigated. The SANS results confirm the tendency of H2DEH[ MDP] -Fe( III) species in aromatic diluents to form rod-like aggregates characteristic by a constant cross section and a length which increases with increasing amounts of metal in the organic phase. Particle growth is independent of the acidity of the aqueous solutions from which the metal is extracted. These results are important for understanding the chemistry underlying the solvent extraction behavior H₂DEH[ MDP] and its practical application in separation procedures.     

SOLVENT EXTRACTION OF ANTIMONY (III), BISMUTH (HI), LEAD (II) AND TIN (IV) WITH BIS(2,4,4-TRIMETHYLPENTYL)PHOSPHINODITHIOIC ACID (CYANEX 301®)

The solvent extraction of antimony (in), bismuth (111), lead (II) and tin (IV) from aqueous hydrochloric acid solutions by bis(2,4,4-trimethylpentyl) phosphinodithioic acid (Cyanex 301® denoted HL) in kerosene + 10 % v/v n-decanol was investigated. Lead (II), tin (IV), bismuth (III) and antimony (III) are efficiently extracted by Cyanex 301® up to about 5, 6, 9 and 11 mol.L^1? HCl, respectively. The corresponding extracted species were identified as PbL₂, SnCl₂L₂, BiL₃ and SMvj. However, it was observed that Sn (IV) can be moderately extracted from the aqueous phase by the mere mixture of kerosene and n-decanol above 9 mol.L^1?HCl. In all cases, extraction equilibrium was reached within a few minutes. Finally, a thermodynamic modelling of the extraction system was developed in the particular case of lead (II).     

SOLVENT EXTRACTION OF COBALT AND NICKEL IN BIS (2,4,4-TRI-METHYLPENTYL) PHOSPHINIC ACID, “CYANEX -272”

ABSTRACT A study has been made of the extraction of cobalt and nickel from sulfate solutions into bis(2,4,4 tri-methylpentyl) Phosphinic acid - “Cyanex 272”, diluent Esso solvent DX 3641, for both high and low metal loading in the organic phase. In dilute solution, 0.01 M, extraction constants and enthalpies were determined for both metals. The extraction of cobalt was always favored over that of nickel, increasing with increase in temperature. No structure change with temperature was found for the cobalt-Cyanex complex. Phase modifiers were found to effect the selectivity of “Cyanex 272” for cobalt.

At high metal loading, equilibrium curves for cobalt were fitted using semi-empirical curve fitting, while for nickel a straight line variation was observed. Organic phase polymerization was observed for both metals the degree of aggregation increasing with increase in loading. A step change increase in the viscosity of the organic phase was observed at high cobalt loading. Phase modifiers proved to be ineffective In reducing the increase in organic phase viscosity.     

SANS STUDY OF AGGREGATION OF THE COMPLEXES FORMED BY SELECTED METAL CATIONS AND P,P'-DI(2-ETHYLHEXYL) ETHANE- AND BUTANE-DIPHOSPHONIC ACIDS∗

ABSTRACT

The aggregation of several metal complexes formed during solvent extraction with P,P'-di(2-ethylhexyl) ethanediphosphonic acid, H₂DEH[EDP], and by P,P'-di(2-ethylhexyl) butanediphosphorac acid, H₂DEH[BuDP], in deuterated toluene, has been investigated by small angle neutron scattering (SANS). With H₂DEH[EDP], the extraction of Ca(II), La(IH) and U(VT) does not disrupt the cyclic hexameric structure of the ligand in solution. Fe(III) and Th(IV) complexes of H₂DEH[EDP], on the other hand, exhibit a very modest tendency to aggregate but only at very high metal loading in the organic phase. With H₂DEH[BuDP], the extraction of Ca(H), La(III), U(VI) and Th(IV) is not accompanied by significant aggregation of the metal complexes The Fe(HI)-H₂DEH[BuDP] complexes, however, form long cylindrical aggregates similar to those previously observed with P,P'di(2-ethylhexyl) methanediphosphonic acid, H₂DEH[MDP]. The aggregation behavior of the various metal-extractant species is discussed in light of the information obtained from earlier solvent extraction, vapor pressure osmometry, and infrared spectroscopy studies.