Description of the Extraction of Rare Earth Element Nitrates from Weakly Acidic Solutions with Concentrated Tributyl Phosphate Solutions

Radiochemistry - A mathematical model based on the published data was developed for the extraction of REE (from La to Lu, including also Y) nitrates in a wide concentration range in weakly acidic...     

Uranium(IV) Complexes Formed in Extraction with Tributyl Phosphate from Nitric Acid Solutions

Speciation of U(IV) in tributyl phosphate (TBP) solutions prepared by extraction of U(IV) from 2 M HNO₃ was studied. The electronic spectra showed that in the solutions containing from 3 to 60% TBP a mixture of disolvate U(NO₃)₄(TBP)₂ and hydrates with hypothetical formula (TBP) _m ...[U(NO₃) _k · (H₂O) _n ]^(4-k)+ (k = 3 or 4) is formed. Within the 70-100% concentration range, the hexanitrate complex (TBP) _n ...2H₅O₂(H₂O) _p ⁺...[U(NO₃)₆]^{2 -} also appears. In undiluted TBP, as the concentration of uranyl nitrate increases, first the hexanitrate complex and then hydrated complexes of U(IV) gradually disappear. At uranium concentration more than 300 g l^-1, only U(IV) tetranitrate disolvate exists in the organic phase.     

Electron Microscopy Studies on Ultrafine Zirconia Powders from Solvent Extraction with Tributyl Phosphate in Kerosene

Solvent extraction of Zr(IV) with TBP in kerosene was used to precipitate precursory zirconia which was then processed to produce ultrafine zirconia powders. The powder prepared was examined and characterized with transmission electron microscopy (TEM) and X-ray diffraction (XRD). Effects of the conditions of preparation on powder properties were especially investigated.It was found the preclpitate was gel-like material with heterogeneous porosity. The gel transformed to polycrystalline particles when calcined to ultrafine powder at 600℃. The composition of the loaded organic phase and the conditions of washing the precipitate are two main factors affecting the properties of powder obtained     

Extraction of REE(III) Nitrates with Polymer-Supported Tributyl Phosphate

Extraction of La, Ce, Pr, Nd, Sm, and Y(III) nitrates with polymer-supported TBP in the presence of 1-5 M NaNO₃ in the aqueous phase is studied. The extraction isotherms are described taking into account formation of [Ln(NO₃)₃(TBP) _j ](o) (j = 3, 4) in the extractant phase. The extraction constants corrected for the TBP concentration in the extractant phase are considerably higher than in the cases of extraction with neat TBP or TBP supported on a porous material (Teflon).     

用TBP萃取分离锆和铪的工艺研究

研究了以碱熔-盐酸法代替碳氯法制备氧氯化锆溶液,用TBP(磷酸三丁酯)萃取分离锆、铪的工艺.研究结果表明:碱熔-盐酸法制备氧氯化锆,通过提纯可以获得低硅的氧氯化锆溶液,用TBP萃取不产生乳化,两相分离清楚.经小试、中试和扩大连续运转试验,证实了分离效果好、萃取过程不产生乳化、工艺操作稳定、回收率高,可获得原子能级的氧化锆和氧化铪.用TBP萃取分离锆和铪可应用于工业生产.     

Preparation of Pt/C Nanocatalysts by Ethylene Glycol Method in Weakly Acidic Solutions

Pt/C catalysts were prepared by ethylene glycol (EG) method in weakly acidic solutions adjusted by sodium citrate (Na3Cit), sodium acetate (NaAc) and sodium hydroxide (NaOH), separately. The effects of alkalizing agent, pH and temperature were investigated by transmission electron microscopy (TEM) and CV. The composition and structure of Pt/C catalyst prepared at optimal conditions of 140℃ and pH=6.7 adjusted by Na3Cit was further characterized by X-ray photoelectron microscopy (XPS) and X-ray diffraction (...     

Dissolution of U,Np, Pu,and Am Oxides and Their Mixtures in Tributyl Phosphate Saturated with HNO3

It was shown for the first time that weighable amounts of uranium dioxide and its mixtures with Np, Pu, and Am in the form of solid solutions can be efficiently and quantitatively dissolved in the presence of tributyl phosphate saturated with HNO₃. Individual PuO₂ and NpO₂ are not dissolved under these conditions. In treatment of a mechanical mixture of UO₂ with PuO₂ or NpO₂, uranium is completely dissolved, while plutonium and neptunium remain in the precipitate.     

Separation of REE(III) and Am(III) by Extraction with Compounds of Zirconium and Dibutyl Phosphoric Acid from Solutions of Nitric and Hydrochloric Acids

Radiochemistry - The behavior of rare-earth elements (REE) and americium during their extraction with compounds of zirconium and dibutyl phosphoric acid (DBPA) in various solvents from solutions of...     

Extraction of Am(III) and Rare-Earth Elements from Nitric Acid Solutions with Dibutyl Diphenylphosphinylmethylphosphonate

Extraction of HNO₃ and trace amounts of Am, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu nitrates from aqueous HNO₃ with solutions of dibutyl diphenylphosphinylmethylphosphonate in dichloroethane was studied. The stoichiometry of the extractable solvates was determined, and the apparent extraction constants were calculated.     

Extraction of Am(III) and Lanthanides from Nitric Acid Solutions with Polyfunctional Organophosphorus Acids

Extraction of microamounts of Am, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu nitrates from aqueous HNO₃ with solutions of (diphenylphosphinylmethyl)phenylphosphinic, (di-p-tolylphosphinylmethyl)phenylphosphinic, (di-p-anisylphosphinylmethyl)phenylphosphinic, and (dioctylphosphinylmethyl)phenylphosphinic acids and of butyl hydrogen (diphenylphosphinylmethyl)phosphonate in toluene was studied. The metal : extractant ratio in the extractable species was determined.     

Extraction of Am and Rare-Earth Elements from Nitric Acid Solutions with Ethyl Bis(diphenylphosphinylmethyl)phosphinate

Extraction of HNO₃ and microamounts of Am, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO₃ solutions with solutions of ethyl bis(diphenylphosphinylmethyl)phosphinate in dichloroethane was studied. The stoichiometry of the extractable complexes was determined, and the effective extraction constants of HNO₃ and Am were calculated. With increasing number of phosphoryl groups in the extractant molecule, the extraction of Am(III) and rare-earth elements from HNO₃ solutions increases.     

Description of the Extraction of Trivalent REE and TPE Nitrates with Tributyl Phosphate and Its Solutions in Paraffins in the Presence of Nitric Acid and Salting-out Agents Using a Unified Model

Radiochemistry - The extraction of trivalent REE and TPE nitrates with tributyl phosphate and its solutions in paraffins at room temperature in the presence of HNO3 is described mathematically...     

Extraction of Am(III) from Nitric Acid Solutions with Bis(diphenylphosphinylmethyl)phosphinic Acid

Extraction of trace quantities of Am(III) from aqueous HNO₃ solutions with solutions of bis(diphenylphosphinylmethyl)phosphinic acid (I), bis[2-(diphenylphosphinyl)phenoxymethyl]phosphinic acid (II), and bis[2-(diphenylphosphinylmethyl)phenoxymethyl]phosphinic acid (III) in dichloroethane was studied. The stoichiometry of the extractable complexes was determined; the effect of organic diluent on the extraction was considered. The extractive power of the reagents toward Am(III) grows in the order III < II < I. Acid I surpasses in the extractive power a neutral bidentate extractant, tetraphenylmethylenediphosphine dioxide (TPMDPD), by three orders of magnitude. A synergistic effect in extraction of Am with mixtures of TPMDPD and acid I was revealed.     

Extraction of Scandium from Various Media with Triisoamyl Phosphate: 1. Extraction of Sc and Impurity Metals from Aqueous Nitric Acid Solutions

The main features of extraction of Sc from aqueous nitric acid solutions with triisoamyl phosphate (TIAP) were studied. It was shown that Sc passes into the organic phase in the form of Sc(NO₃)₃·3TIAP. The extraction isotherms of Sc from its aqueous HNO₃ solutions and from those containing salting-out agents (LiNO₃, NH₄NO₃) with TIAP in dodecane were obtained. The distribution factor of Sc was studied in relation to the concentrations of TIAP, salting-out agent, and HNO₃. The extraction of Sc and impurity metals (Zr, Th, REE) with TIAP was studied at widely varied HNO₃ concentration in the aqueous phase. The separation factors of Sc from impurity metals were determined.     

Extraction of Am(III) and Rare-Earth Elements from Nitric Acid Solutions with (Diphenylphosphinylmethyl)phenylphosphinic Acid

Extraction of microamounts of Am, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu nitrates from aqueous HNO₃ with solutions of (diphenylphosphinylmethyl)phenylphosphinic acid in dichloroethane was studied. The stoichiometry of the extractable complexes was determined. Synergistic enhancement of the extraction of rare-earth elements in the presence of tetraphenylmethylenediphosphine dioxide was revealed.     

Radiation Chemical Behavior of Tributyl Phosphate,Dibutylphosphoric Acid,and Its Zirconium Salt in Organic Solutions and Two-Phase Systems

Radiation-induced and hydrolytic decomposition of HDBP and its zirconium salt in organic solutions and two-phase aqueous-organic systems in the presence of TBP and nitric acid is studied. The yields of radiation-induced decomposition of HDBP and temperature dependences of its hydrolysis rate constants are determined. Kinetic equations for radiation-induced decomposition of HDBP are derived.__________Translated from Radiokhimiya, Vol. 47, No. 4, 2005, pp. 359–363.Original Russian Text Copyright © 2005 by Egorov, Tkhorzhnitskii, Zilberman, Shmidt, Goletskii.     

Extraction of Am(III) and Eu(III) from Nitric Acid Solutions with Bidentate Neutral Organophosphorus Compounds

Extraction of HNO₃ and microamounts of Am and Eu from nitric acid solutions with solutions of bidentate butyl (phosphorylmethyl)phenylphosphinates R₂P(O)CH₂P(O)Ph(OBu) [R = octyl (I), phenyl (II), p-tolyl (III), p-anisyl (IV)] in 1,2-dichloroethane was studied. The stoichiometry of the extractable complexes was determined, and the apparent extraction constants were calculated. The extractive power of the reagents studied toward HNO₃ increases in the order II < III < IV < I, and toward Am(III), in the order I < II < III < IV.     

Preparation and Characterization of Ultrafine ZrO_ Powders from Solvent Extraction of Zr(Ⅳ) with Tri-n-butyl Phosphate in Kerosene from Nitric Acid Solutions

Zr(IV) was extracted by tri-n-butyl phosphate in kerosene from concentrated nitric acid solutions and the formation of the third phase during extraction was experimentally investigated. Zirconia powders were prepared by using the loaded organic phase as the bulk solution precipitated with aqueous ammonia or NaOH solution. The powder prepared was characterized with TEM, XRD,EDAX and TG-DTA. Effects of some conditions on powder preparation were studied and it was shown that nanosized particles could be obtained from this extraction system but conditions should be carefully controlled for powder purity and particle size.     

Extraction of Actinides from HNO3 Solutions with Solutions of Dialkyl Methylphosphonates

Extraction of actinides with dialkyl methylphosphonates was studied with the aim to find a compromise between the use of highly effective but expensive chemicals, on the one hand, and weakly effective but cheap and readily available chemicals, on the other hand, and also to find possible ways of utilization of methylphosphonic dichloride, which is the starting substance in syntheses not only of dialkyl methylphosphonates, but also of chemical weapons. In systems with 3 M HNO₃ as the aqueous phase and a solution of tributyl phosphate (TBP), diisoamyl methylphosphonate (DIAMP), or bidentate diphenyl(carbamoylmethyl)phosphine oxide (Ph₂Bu₂) in dichloroethane as organic phase, at equal concentrations of the organophosphorus compounds, the distribution coefficients of Am(III) increase in the order TBP <; DIAMP < Ph₂Bu₂ in a proportion of 1 : 50 : 5 × 10⁴. Mixtures of dialkyl methylphosphonates and acidic phosphonates show a synergistic effect, which, however, can be utilized only at [HNO₃] > 0.1 M and [HIAMP] < 1.5 M (HIAMP is isoamyl hydrogen methylphosphonate).     

Phase Separation in Ternary Liquid Systems Tetradecane-n-Octanol (or Cyclohexanone)-Lanthanide(III) Nitrate Solvates with Tri-n-Butyl Phosphate

The phase diagrams of ternary liquid systems tetradecane-n-octanol (or cyclohexanone)-lanthanide(III) nitrate solvates with tri-n-butyl phosphate [Ln(NO₃)₃(TBP)₃, Ln = La, Ce, Pr, or Sm] at T = 298.15 K were studied. These diagrams contain areas of homogeneous solutions and an area of separation into two liquid phases (I, II). Phases I and II are enriched in tetradecane and Ln(NO₃)₃(TBP)₃, respectively. n-Octanol and cyclohexanone mainly pass into phase II.