EXTRACTION OF NEPTUNIUM AND PLUTONIUM NITRATES WITH n-OCTYL(PHENYL)-N,N-DIISOBUTYL-CARBAMOYLMETHYLPHOSPHINE OXIDE∗

Distribution equilibria of Np and Pu in various valence states and stripping of Np(V) were studied in a system involving 0.20 M n-octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide + 1.2 M tributyl phosphate in dodecane as a solvent. Np(V) is weakly extractable at <2 M nitric acid but more effectively extractable at >3 M nitric acid, due to the disproportionation of Np(V) to Np(IV) and Np(VI). Addition of nitrous acid to solutions containing Np(V) increases the over-all extractabllity of Np, due to its partial oxidation to Np(VI). This is also the case In the presence of oxalic acid, both at room temperature and at 40^°C. Both Np(IV) and Np(VI) are highly extractable, but the reduction of Np(V,VI) to Np(IV) is slow even with a reductant as strong as sodium formaldehyde sulfoxylate. Pu(IV) is highly extractable and its reduction to Pu(III) with sulfoxylate Is incomplete in the two-phase system if the aqueous phase contains >0.5 M nitric acid. Extracted Np(VI) can be stripped by reduction to Np(V). The stripping rate is, however, slow with nitrous acid as the reductant at low nitric acid concentration. The reduction of Np(VI) by hydrogen peroxide is fast, but is followed by further reduction to Np(IV). Sulfurous acid reduces Np(VI) rapidly and, if no iron is present, only to Np(V), but Fe(II) induces further reduction to Np(IV).     

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.     

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.     

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.     

THE EXTRACTION OF SELECTED ACTINIDES IN THE ( III) (IV) AND ( VI) OXIDATION STATES FROM HYDROCHLORIC ACID BY Oπ D( iB) CMPO: THE TRUEX-CHLORIDE PROCESS∗

The extraction of tetravalent Th, Np, and Pu and hexavalent U from hydrochloric acid was studied using octyl(phenyl)-N,N-diiso-butylcarbamoylmethylphosphine oxides, 0π D(iB)CMP0 or CMPO, dissolved in tetrachloroethylene (TCE). A 0·5 MCMPO solution in TCE was found to be an extremely effective extractant for the tetravalent actinides and U(VI) from moderate to concentrated HC1. Extractant dependencies of the distribution ratios of Th(IV), U(VI), and Pu(IV) were 3rd, 2nd, and 3rd power, respectively, indicating the following species: ThCl₄’3CMPO, UO₂Cl₂2CMP0, and PuCl₄»3CMPO. The distribution ratios of a variety of non-actinide elements, including selected alkali, alkaline earths, Al, transition and post-transition metal ions were also measured from 2 Mand 6 M_ HC1. Based on the distribution ratios of tri-, tetra-, and hexavalent actinides from chloride media, a generic actinide extraction/recovery process was developed for the removal of actinides from chloride salt wastes. The process is called TRUEX-Chloride.     

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.     

EQUILIBRIUM AND KINETIC STUDIES FOR THE ADSORPTION OF MN(II) AND CO(II) FROM AQUEOUS MEDIUM USING AGAR–AGAR AS SORBENT

An extensive increase in industrial activities and environmental accidents in recent years have greatly contributed to increasing metal pollution in water resources, thereby causing threats to terrestrial as well as aquatic life. The toxicity of metal pollution is slow and long lasting, as these metal ions are nonbiodegradable. The most appropriate solution for controlling the biogeochemistry of metal contaminants to produce high-quality treated effluents from polluted wastewaters is sorption technique. Agar–agar, a readily available seaweed, was used as sorbent for the removal of Mn(II) and Co(II) from aqueous media. Batch experiments were performed to study adsorption as a function of process parameters: sorption time, initial pH, concentration of sorbate and sorbent. The Freundlich model fitted best with the experimental equilibrium data between the two adsorption isotherm models tested. The kinetic data correlated well with the Lagergren pseudo-second-order kinetic model for the sorption of both Mn(II) and Co(II) using agar–agar. Adsorbed metal ions were quantitatively recovered from the spent adsorbent using 5.0 mol L^?1 HCl. The efficiency of agar–agar for decontaminating Mn(II) and Co(II) from electroplating effluent has also been evaluated. The results proved agar–agar to be a favorable adsorbent to remove and recover Mn(II) and Co(II) from waste effluent for further use in diversified industrial applications.     

THE EXTRACTION OF CATIONIC RUTHENIUM COMPLEXES FROM AQUEOUS MEDIA BY α-TIN(IV) HYDROGEN PHOSPHATE

ABSTRACT

The ruthenium species [Ru(NH₃)₆]³⁺ was adsorbed by the surface of (α-Sn(HPO₄)₂.2H₂O [SnP]) α-tin(IV) hydrogen phosphate. The ruthenium(II)-containing cation [Ru(NH₃)₆]²⁺, however, has been directly intercalated into (SnP). Since the corresponding ruthenium(III) complex cation was not so intercalated, a new self-catalysed intercalation mechanism involving labile ammonia ligands from the ruthenium(II) has been proposed. At high loadings, guest ruthenium(II) species were oxidised to ruthenium(III).     

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%.     

PREPARATION AND ADSORPTION PROPERTIES OF THE POLYSTYRENE RESIN HAVING DIETHYLENETRIAMINE-N,N′- BIS(METHYLENEPHOSPHONATE) GROUP

Styrene-divinylbenzene copolymer beads containing diethylenetriamine-N,N′-bis(methylenephosphonate) group have been synthesized. The adsorption properties, of the present resin for some trivalent and bivalent metal ions have been examined. The selectivity sequence of the present resin at pH lower than 2.0 is as follows: Ga(III)> A1(III)> Sm(III)>Cu(II)>Co(II)>Zn(II)>Ca(II). The present resin reveals remarkable selectivity for the trivalent metal ions. The selective concentration of In(III) Ga(III) and Sm(III) from an acidic aqueous solution has been demonstrated by using a column of the present resin.     

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).     

EFFECT OF SELECTED β-DIKETONES ON THE SYNERGICEXTRACTION OF COBALT(II) BY TRIPHENYL-PHOSPHINE OXIDE IN BENZENE

Abstract

Synergic extraction of Co(ll) by thenoyltrifluoroacetone (HTTA), Pivaroyltrilluoioacetone (HPvTA) or hexafiuoroacetylacetone (HHFA) mixed with triphenyiphosphine oxide (ph₃PO) in benzene from perchlorate media has been investigated. It ’ was found that in all the systems studied, Co(ll) is synergistically extracted as CoL₂.ph₃PO, where L stands for the different chelating ligands. The obtained equilibrum constants for the chelating and adduct systems indicated that: i- the weaker the acidity of the chelating ligand, the higher the overall aqueous phase formation constant of the metal chelate (β₂ ), ii- the sequence of the extraction constants (K_2,1 ) and the organic phase formation constants for the adduct ( β_2,1) as related to the chelating ligands is TTA> HFA > PvTA, iii- the stability of the adduct is related to both the structure and the pK_avalues of the chelating ligands.     

STUDIES ON “THE THREE CRITICALS AND THE TWO OPTIMUMS”IN MEMBRANE GAS SEPARATION PROCESSES ( I ) “THE THREE CRITICALS”AND THEIR RELATIONSHIPS

提出了“三临二优”（系指临界操作压力比R~-、临界选择系数α~-、临界进料浓度x_f~-和最优操作压力比R~+、最优选择系数α~+）新概念,通过计算、分析和优化等手段,在x_f≥0.40、R≤100、a≤100范围内获得如下通用回归公式R~-=2+B/（α~-+A）,式中A、B仅与临界进料浓度x_f~-有关,并对他们分别进行了回归。此外,还在R≤1000、a≤1000范围内给出了x_f~-=0.95和0.50时的回归公式。     

THE MASS TRANSFER BEHAVIORS OF FE(Ⅲ), CO(Ⅱ) AND NI(Ⅱ) IN SULFURIC ACID WITH CYANEX302 BY USINGMICROPOROUS HOLLOW FIBER

In this paper the mass transfer behaviors of Fe(Ⅲ), Co(Ⅱ) and Ni(Ⅱ) with Cyanex302(bis(2,4,4- trimethylpentyl)monothiophosphinic acid) from sulfate medium by using hollow fiber membrane in counter-currently circulating operation were studied. The effect of acidity in aqueous solution and the extractant concentration on the mass transfer coefficient (Kw) was discussed. The reaction mechanism of membrane extraction was considered as a false one series reaCtion and the rate controlling step was membrane resistance. When the value of Kw arrived at 1.0 × 10-6 m/s, △pH:CoFe equaled tO 6.225, and △pH:NiFe was bigger than △p HCoFe.     

EFFECT OF CHAIN LENGTH OF ALKANE-1-HYDROXY-1, 1′-METHYLDIPHOSPHONIC ACIDS ON THE IRON (III) LIQUID–LIQUID EXTRACTION

ABSTRACT

(1-Hydroxy-1-phosphonohexadecyl) phosphonic acid (HPHPA) and (1-hydroxy-1-phosphonododecyl) phosphonic acid (HPDPA) were prepared by reaction of phosphorus trichloride with palmitic and lauric acids, respectively. After purification, these products were characterized by elemental microanalysis and by IR, ¹H, ³¹P?NMR spectroscopies. In this paper, we propose a tentative assignment for the shifts of those two ligands and their specific complexes with iron (III). A spectroscopic analysis has showed that coordination of iron (III) takes place via oxygen atoms. We also measured the extraction of Fe⁺³ by HPHPA and HPDPA from [CCl₄-Octanol (v/v: 90%/10%)] solutions. The complexes formed in the organic phase may be Fe[C₁₁ H₂₃C(OH)(PO₃H)₂]Cl, 3H₂O with HPDPA and Fe[C₁₅H₃₁C(OH) (PO₃H)₂]Cl, 3H₂O with HPHPA, respectively. HPHPA as ligand exhibits a stronger extracting power for Fe³⁺ and has a more hydrophobic character than HPDPA.     

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.     

MOLECULAR MODELLING AND SPECTROSCOPIC STUDIES OF THE INTERACTIONS BETWEEN CHELATING AND ELECTRON-DONOR METAL EXTRACTANTS: THE SYSTEM TRI-N-OCTYLPHOSPHINE OXIDE - 3-PHENYL-4-BENZOYL-ISOXAZOL-5-ONE ( ‘HPBI‘ ) IN WET TOLUENE AND CHLOROFORM.

ABSTRACT

IR, NMR (^H, ¹³C and ³¹P) and electronic spectroscopies have been used to study the tautomeric forms of 3-phenyl-4-benzoyl-isoxazol-5-one, "HPBI", and its interaction with tri-rc-octylphosphine oxide, ‘TOPO’, in wet toluene or benzene, and in chloroform. These metal extracting media have been compared with analogous solutions containing l-phenyl-3-methyI-4-acyI-pyrazoI-5-oIs. The spectroscopic results are compared with those of molecular modelling studies. Spectroscopic criteria that allow a choice between the various tautomeric forms of pyrazolones or isoxazolones are briefly reviewed.

In the solid, in wet toluene, benzene or chloroform solutions, HPBI mainly exists as a fi-keto-enol chelate, quite different from its tautomeric form in methanol, which is most probably a diketone-enamine. Molecular modelling studies show that the energy difference between the chelated 5-hydroxy- and 5-one- tautomeric forms of the free molecule is rather low. They cannot be discriminated by spectroscopy

As shown by UV and PMR spectroscopies, the interaction of TOPO with HPBI is stronger than with 4-acyl-5-hydroxypyrazoles (acyl: lauroyl, benzoyl, thenoyl). The most likely tautomeric form for HPBI in the H-bonded [TOPO.HPBI] moiety is the diketone-enamine (b’). Accordingly, molecular modelling studies show that the R3PO-H-NHPBI hydrogen bond is 0.15A shorter than the R3PO-H-OHPBI one, when comparing two isomeric forms of the 1:1 [TOPO.HPBI]complex.     

THE SWELLING BEHAVIOR OF (W/O)/W LIQUID SURFACTANT MEMBRANE (Ⅰ) ADSORPTION OF SURFACTANT AT THE INTERFACE AND THE SWELLING CAUSED BY EMULSIFICATION

The concept of effective concentration of surfaetant in membrane phase has been proposed,considering the high ad-sorption density of the surfactant at the droplet interfaces in LSM system.The effective concentration of surfactant,C_2,can be estimated by Eq.(7)—(9).The swelling caused by emulsification during the initial dispersion process was investigated.The swelling rate wasmeasured by a density method.A model for estimating the“Emulsification”swelling rate,F_(se),has been proposed,basedon a mechanism of swelling due to the entrainment of water resulted from the interracial turbulence and emulsification inthe initial dispersion process.It has been found that Eq.(26)gives excellent fit to the experimental data of Fujinawa,etal.and of the authors.     

CALCULATION OF THERMODYNAMIC PROPERTIES OF REAL FLUIDS AND VAPOR-LIQUID EQUILIBRIA BY USING A CANONICAL PARTITION FUNCTION (Ⅰ) THERMODYNAMIC PROPERTIES OF PURE FLUIDS

The Anderson-Prausnitz equation of state has been improved by modifying the attractive term of the generalized van der Waals canonical partition function.In this modification, the parameter characterizing the intermolecular attractive forces is considered to depend not only on temperature but also on density.By this new equation of state the calculated results for pressure and fugacity coefficient of pure gases have slightly better accuracy than those by the original Anderson-Prausnitz equation, and those for saturated vapor pressure are in good agreement with observed results.