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).     

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.     

THE SOLVENT EXTRACTION OF SELECTED ORGANIC COMPLEXANTS BY TRUEX PROCESS SOLVENT∗

The extraction by TRUEX solvent of ¹⁴C-labelled acetic, glycolic, and citric acids, and ¹⁴C-labelled glycine, EDTA, and ethylenediamine has been studied from aqueous solutions having different nitric acid concentrations. Only acetic and citric acids are extracted to a significant extent. Their behavior can be compared to that of oxalic acid. If the aqueous phase contains a high concentration of aluminum and iron(III) species, as in some nuclear waste solution, the extraction of aqueous complexants into the organic phase is strongly suppressed. By measuring distribution ratios of irradiated ¹⁴C-labelled acetic acid, citric acid and EDTA, it has been demonstrated that the radiolytic degradation of these compounds leads, at least in part, to oxalic acid. A scrub procedure, utilizing basic aluminum nitrate, has been successfully tested in order to remove any co-extracted oxalic acid from the TRUEX solvent.     

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.     

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.     

LIQUID-LIQUID EXTRACTION OF BSA BY USING CTAB-HEXANOL-OCTANE REVERSED MICELLAR SYSTEM

1 INTRODUCTIONIn biotechnology there is a need for new protein recovery process,which combines a highselectivity for the desired product with substantial concentration increased and easy to scale-up.In this context,liquid-liquid extraction with reversed micellar phase might serve this purpose.Reversed micelles are aggregates of surfactant molecules containing an inner core of water mole-cules,dispersed in a continuous organic solvent medium.These systems are opticallytransparent and thermodynamically stable.It has beendemonstrated [1,2]that under certainconditions proteins can be transferred from an aqueous phase towards a reversed micellarphase or vice versa(Fig.1)     

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.     

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.     

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.     

ENHANCEMENT OF THE SINERGIC EXTRACTION OF COBALT WITH MIXTURES OF l-PHENYL-3-METHIL-’4-BENZOTtLPIRAZOL-5-ONE AND DODECYLAMINE BY EMULSION FORMATION.

The synergic extraction of cobalt (II) from sulphate medium (O.33M) with l-phenyl-S-methyl-l-benzoylpyrazol-S-one (HL) and n-dodecylamine (Am) in toluene has been explained by: of constant logK_s=5.15. When the extraction is performed from perchlorate and nitrate media ([X]=[C10₄]=[N0₃ ]=1.0M), an emulsion, in contact with a clear organic phase, is formed owing to the amphiphilic properties of AmH.X. This Induces an enhancement of the synergic extraction at low AmH.X concentrations. The extraction equilibrium is : Where int. denotes interfacial species and logK +log{AmH.X} -log[X;}_int =logK_int = -6.10 and -6.25 (X?ClO₄ and NO₃). (AmH⁺ denotes single or aggregated ammonium cations).     

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.     

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).     

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.     

KINETICS OF HYDROGEN PRODUCTION BY PARTIAL OXIDATION AND STEAM REFORMING OF METHANOL

1　INTRODUCTIONWithdecreasingoilreservesanddeterioratingenvironment,the problemofenergyandenvironmenthasbecomethemainobstacletothesustainabledevelopmentofeconomyandthe progressofmankind Inmanydevelopedcountriesfuelcellsareextensivelyresearched Inallkindso…     

THE SYNERGISTIC SOLVENT EXTRACTION OF RADIUM FROM ALKALINE NITRATE MEDIA BY DICYCLOHEXANO-21-CROWN-7 COMBINED WITH 2-METHYL-2-HEPTYL NONANOIC ACID EQUtUBRIUM REACTIONS AND METAL ION COMPETITION∗

The equilibria in the solvent extraction of radium from aqueous sodium nitrate/sodium hydroxide solutions by toluene solutions of dicyclohexano-21-crown-7 (DC21C7). 2-methyl-2-heptylnonanioc acid (HMHN). and mixtures of the two reagents are examined. The mixed reagents are synergistic in the extraction of radium and selective for radium over other alkali and alkaline earth elements. The dependencies of the extraction on pH and reagent concentration were utilized in computer modeling to estimate the stochiometry of the extracted complexes and equilibria involved the extraction. Three organic-phase species were identified in the extraction under basic (pH 11-13) conditions. With A = MHN^?. B = DC21C7 and assuming NaA is a 10-fold aggregate they are. RaA₂B.NaA. Log K = 3.57: RaA NaA. Log K = 0.99: and B 2NaA. Log K = ? 0.41. The effect of the presence of various concentrations of sodium     

ETHANOL FERMENTATION OF MIXED GLUCOSE AND XYLOSE BY PICHIA STIPITIS

Pichia stipitis CBS 5773 yeast cells were used to ferment the mixed substrates consisted of glucose andxylose to produce ethanol.The effects of aeration rate,initial substrate concentration and pH on substrateutilization and ethanol yield were evaluated.During batch fermentation,the oscillation phenomena in cell growthwere observed at low aeration rate,whereas the diauxic growth at high aeration rate.The substrate utilizationratio and ethanol yield reached 95％ and 0.46g/g respectively under appropriate operation conditions.Amodified unstructural model was proposed to simulate the diauxic cell growth,substrate consumption andproduct formation.     

THE EXERGETIC EFFICIENCY OF MSF PROCESS AND THE CONDITIONS OF DESALINATION BY WASTE HEAT

The exergy losses and thermodynamic efficiency of MSF plant with brine recirculation are discussed bymeans of temperature difference functions proposed by the auther.In a MSF plant,the irreversible losses are found mainly in irreversible heat-transfer and flash evaporationprocesses.However,the basic variables are the temperature drop from stage to stage and the temperaturedifferences between flashed vapor and cooling water.In this paper,the flash temperature difference func-tion,the heat transfer temperature difference function and the total temperature difference function are sug-gested.The proposed temperature difference functions of MSF plant provide a convenient tool to analyse theirreversible behavior and evaluate the exergetic efficiency of this system,because without such improvement thecalculation of the exergetic efficiency of a MSF plant according to the classical formula will be not onlyinconvenient but also insignificant.As a result of present analysis,the reasonable parameters based on theenergy consumption are easily chosen.The above-mentioned principles are confirmed by commercial plants and a pilot plant in Tianjin.     

MATHEMATICAL AND EXPERIMENTAL ANALYSIS OF AIR SEPARATION BY HOLLOW FIBER MEMBRANES

Approximate solutions for gas separation by hollow fiber membranes have been developedby several investigators.However,there are few reports of experimental verification of the models forhigh stage cut separations.In this work,an approximate mathematical model was developed and wasexperimentally verified for high stage cut air separation.Both countercurrent and cocurrent now pat-terns were used.In addition,the applicability of feed-inside mode for low stage cut air separation byhollow fiber membrane was examined.It was found that feed-inside mods was more advantageousthan feed-outside mode when used for the generation of oxygen-enriched air.     

THE APPLICATIONS OF A GENERALIZED EQUATION OF STATE TO THE CORRELATION AND PREDICTION OF PHASE EQUILIBRIA∗

Two methods of generalizing an equation of state are demonstrated and their limitations are outlined. One method involves the correlation of the equation of state constants and the second method involves a recently proposed Generalized Corresponding States Principle based on the properties of two (nonspherical) reference fluids. The PVT properties of pure fluids are represented by a new cubic equation of slate with four parameters which are obtained from vapor pressure and saturated liquid density data. It is demonstrated how a limited amount of data on key components may be used to obtain phase equilibria in mixtures.