Effect of Anions on the Extraction of Lanthanides (III) by N,N′‐Dimethyl‐N,N′‐Diphenyl‐3‐Oxapentanediamide

Abstract

The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y by N,N′‐dimethyl‐N,N′‐diphenyl‐3‐oxapentanediamide (DMDPhOPDA) in 1,2‐dichloroethane from aqueous media containing ClO₄ ^?, PF₆ ^?, (CF₃SO₂)₂N^? anions or by DMDPhOPDA in 1,2‐dichloroethane in the presence of 1‐butyl‐3‐methylimidazolium bis[(trifluoremethyl)sulfonyl]imide ([C₄mim][Tf₂N]) and 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([C₄mim][PF₆]) from HNO₃ solutions has been studied. The effect of HNO₃ concentration in the aqueous phase and that of the extractant concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes has been determined. The addition of HPF₆ and (CF₃SO₂)₂NH or their salts to the aqueous HNO₃ or HCl solutions leads to an enchancement of lanthanides (III) extraction by DMDPhOPDA. A considerable synergistic effect was observed in the presence of ionic liquids (IL) in the organic phase containing DMDPhOPDA. This effect is connected with the hydrophobic nature of the IL anion. The distribution of ILs between the equilibrium organic and aqueous phases can govern the extractability of lanthanides (III) in DMDPhOPDA‐IL systems.     

Synergistic Extraction of Lanthanides(III) by Mixtures of N‐p‐Methoxybenzoyl‐N‐phenylhydroxylamine and 1,10‐Phenanthroline

Abstract

We conducted a study on the equilibrium extraction behavior of the trivalent lanthanide ions (M³⁺), La, Pr, Eu, Ho, and Yb, from tartrate aqueous solutions into chloroform solutions containing N‐p‐methoxybenzoyl‐N‐phenylhydroxylamine (Methoxy‐BPHA, HL) and 1,10‐phenanthroline (phen). The synergistic species extracted was found to be {ML₂(phen) (HL)}⁺(1/2)Tar^2?, where Tar^2? is tartrate ion. The extraction constants were calculated. The extraction separation behavior and extractability of lanthanides are discussed in comparison with the self‐adducted chelate, ML₃(HL)₂, which was extracted in the absence of phen, and synergistic extraction by mixtures of other extractants such as 2‐thenoyltrifluoroacetone, and neutral donors.     

Synergistic Extraction of Lanthanides(III) with N‐p‐Methoxybenzoyl‐N‐Phenylhydroxylamine and Neutral Nitrogen Donors

Abstract

We investigated the extraction equilibrium behavior of a series of trivalent lanthanide ions, (M³⁺), La, Pr, Eu, Ho, and Yb, from tartrate aqueous solutions using a chloroform solution containing N‐p‐methoxybenzoyl‐N‐phenylhydroxylamine (Methoxy‐BPHA or HL) combined with an adductant, 1,10‐phenanthroline (phen) or 2,2′‐bipyridyl (bipy). The synergistic species extracted were found to be {ML₂(phen)(HL)}⁺(1/2)Tar^2? and {ML₂(bipy)(HL)₂}⁺(1/2)Tar^2?, where Tar^2? is the tartrate ion. The stoichiometry, the extraction constants, and the separation factors of these systems were determined. We discuss the extractability and the separation factors in comparison with self‐adduct chelates, ML₃(HL)_2,(o), which were formed in the absence of phen or bipy.     

Application of N,N′‐Dimethyl‐N,N′‐Di(4‐Chlorophenyl)Tetradecyl Malonamide for the Selective Recovery of Iron(III) from Concentrated Chloride Solutions

Abstract

The feasibility of using two new diamides namely; N,N′‐dimethyl‐N,N′‐di(4‐chlorophenyl)malonamide (DMDPhClMA) and N,N′‐dimethyl‐N,N′‐di(4‐chlorophenyl)tetradecylmalonamide (DMDPhClTDMA), as agents for the selective extraction of iron(III) from chloride solution was investigated. A systematic investigation has been carried out on the detailed extraction properties of iron(III) with these extractants from chloride media. The extraction of iron(III) from an aqueous chloride solution in the presence of metal ions, such as Zn(II), Co(II), Mn(II) Cu(II), Pb(II), Ni(II) and Ag(I) was carried out using DMDPhClMA or DMDPhClTDMA in binary and multicomponent mixtures. The quantitative extraction of iron(III) with DMDPhClMA and DMDPhClTDMA in toluene is observed at 4 and 7 M HCl, respectively. The quantitative stripping of Fe(III), from the loaded organic phase was successfully achieved by simple contact with water.     

Extraction of Actinide(III,IV, V,VI) Ions and TcO4 − by N,N,N′,N′‐Tetraisobutyl‐3‐Oxa‐Glutaramide

Abstract

The extraction behavior of U(VI), Np(V), Pu(IV), Am(III), and TcO₄ ^? with N,N,N′,N′‐tetraisobutyl‐3‐oxa‐glutaramide (TiBOGA) were investigated. An organic phase of 0.2 mol/L TiBOGA in 40/60% (V/V) 1‐octanol/kerosene showed good extractability for actinides (III, IV, V VI) and TcO₄ ^? from aqueous solutions of HNO₃ (0.1 to 4 mol/L). At 25°C, the distribution ratio of the actinide ions (D _An) generally increased as the concentration of HNO₃ in the aqueous phase was increased from 0.1 to 4 mol/L, while the D _Tc at first increased, then decreased, with a maximum of 3.0 at 2 mol/L HNO₃. Based on the slope analysis of the dependence of D _M (M=An or Tc) on the concentrations of reagents, the formula of extracted complexes were assumed to be UO₂L₂(NO₃)₂, NpO₂L₂(NO₃), PuL(NO₃)₄, AmL₃(NO₃)₃, and HL₂(TcO₄) where L=TiBOGA. The enthalpy and entropy of the corresponding extraction reactions, Δ_r H and Δ_r S, were calculated from the dependence of D on temperature in the range of 15–55°C. For U(VI), Np(V), Am(III) and TcO₄ ^?, the extraction reactions are enthalpy driven and disfavored by entropy (Δ_r H<0 and Δ_r S<0). In contrast, the extraction reaction of Pu(IV) is entropy driven and disfavored by enthalpy (Δ_r H>0 and Δ_r S>0). A test run with 0.2 mol/L TiBOGA in 40/60% 1‐octanol/kerosene was performed to separate actinides and TcO₄ ^? from a simulated acidic high‐level liquid waste (HLLW), using tracer amounts of ²³⁸U(VI), ²³⁷Np(V), ²³⁹Pu(IV), ²⁴¹Am(III) and ⁹⁹TcO₄ ^?. The distribution ratios of U(VI), Np(V), Pu(IV), Am(III) and TcO₄ ^? were 12.4, 3.9, 87, >1000 and 1.5, respectively, confirming that TiBOGA is a promising extractant for the separation of all actinides and TcO₄ ^? from acidic HLLW. It is noteworthy that the extractability of TiBOGA for Np(V) from acidic HLLW (D _Np(V)=3.9) is much higher than that of many other extractants that have been studied for the separation of actinides from HLLW.     

2,2′‐(Methylimino)bis(N,N‐dioctylacetamide) (MIDOA), A New Tridentate Extractant for Technetium(VII), Rhenium(VII), Palladium(II), and Plutonium(IV)

2,2′‐(Methylimino)bis(N,N‐dioctylacetamide) (MIDOA) was developed as a new extractant for technetium. MIDOA has a similar backbone to TODGA, N,N,N′,N′‐tetraoctyldiglycolamide, where the nitrogen atom bearing a methyl group replaces the ether oxygen in TODGA. MIDOA is highly lipophilic and ready to use in the HNO₃–n‐dodecane extraction system. The distribution ratio (D) for Tc(VII) is extremely high. In addition, Cr(VI), Re(VII), Mo(VI), W(VI), Pd(II), and Pu(IV) are well extracted by MIDOA. MIDOA has high selectivity toward certain oxometallates. The D(Tc) values decrease gradually with HNO₃, H⁺, and NO₃ ^? concentrations, and the log D vs log [MIDOA] dependence indicates the species extracted to be the 1:1 metal‐ligand complex. It is clear that MIDDA [2,2′‐(methylimino)bis(N,N‐didodecylacetamide)] and IDDA [2,2′‐(imino)bis(N,N‐didodecylacetamide)], which have structures analogous to MIDOA, have similar extraction behavior to that of MIDOA.     

Extraction of Palladium(II) from Nitric Acid Solutions with 1‐Benzoyl‐3‐[6‐(3‐benzoyl‐thioureido)‐hexyl]‐thiourea

The extraction of palladium (II) from HNO₃ solutions with 1‐Benzoyl‐3‐[6‐(3‐benzoyl‐thioureido)‐hexyl]‐thiourea (Ia) and several monodentate thiourea derivatives in 1,2‐dichloroethane has been studied. The effect of HNO₃ concentration in the aqueous phase and that of the extractant in the organic phase on the Pd(II) extraction is considered. The stoichiometry of the extracted complexes has been determined. The increasing number of thioamide groups in the molecule of Ia increases its extraction efficiency towards Pd(II). The potentialities of a polymeric resin impregnated with compound Ia for selective extraction of Pd(II) from nitric acid solutions are demonstrated.     

Extraction Properties of 6,6′‐Bis‐(5,6‐dipentyl‐[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridinyl (C5‐BTBP)

Abstract

The extraction of americium(III) and europium(III) into a variety of organic diluents by 6,6′‐bis‐(5,6,‐dipentyl‐[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridinyl (C5‐BTBP) has been investigated. In addition to determining the stoichiometry for the extraction, the dependence of extraction on contact time and temperature was also studied. The resistance of the ligand to gamma irradiation and the possibility to recycle the organic phase after stripping were tested to determine how the molecule would perform in a radiochemical process. Different organic diluents gave different extraction results, ranging from no extraction to distribution ratios of over 1000 for americium(III). In 1,1,2,2‐tetrachloroethane, the extraction and separation of americium from europium and the extraction kinetics were good; a separation factor above 60 was obtained at equilibrium, ～5 min contact time. The extraction capabilities are adequate for C5‐BTBP to be used in a process for separating trivalent actinides from lanthanides. However, C5‐BTBP is susceptible to radiolysis (americium extraction decreases ～80% after a dose of 17 kGy) and may not be the best choice in the processing of spent nuclear fuel. Nonetheless it is a useful starting point for further development of this type of molecule. It could also prove useful for analytical scale separations for which radiolytic instability is less important.     

Extraction of Actinides with Different 6,6′‐Bis(5,6‐Dialkyl‐[1,2,4]‐Triazin‐3‐yl)‐[2,2′]‐Bipyridines (BTBPs)

Abstract

The extraction of Am(III), Th(IV), Np(V), and U(VI) from nitric acid by 6,6′‐bis(5,6‐dialkyl‐[1,2,4]‐triazin‐3‐yl)‐[2,2′]‐bipyridines (C2‐, C4‐, C5‐, and CyMe₄‐BTBP) was studied. Since only americium and neptunium extraction was dependent on the BTBP concentration, computational chemistry was used to explain this behavior. It has been shown that the coordination of the metal played an important role in forming an extractable complex into the organic phase, thus making it possible to extract pentavalent and trivalent elements from tetravalent and hexavalent elements. This is very important, especially because it shows other possible utilizations of a group of molecules meant to separate the actinides from the lanthanides. In addition, the level of extraction at very low or no BTBP concentration was explained by coordination chemistry.     

Separation of Actinides(III) from Lanthanides(III) in Simulated Nuclear Waste Streams using 6,6′‐Bis‐(5,6‐dipentyl‐[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridinyl (C5‐BTBP) in Cyclohexanone

Abstract

An extraction system comprising 6,6′‐bis‐(5,6‐dipentyl‐[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridinyl (C5‐BTBP) dissolved in cyclohexanone was investigated. The main purpose of this investigation was to extract and separate actinides(III) from lanthanides(III), both of which are present in the waste from the reprocessing of spent nuclear fuel. The system studied showed high distribution ratios for the actinides(III) and a high separation factor between actinides and lanthanides (SF_Am/Eu around 150). The extraction kinetics were fast with equilibrium being reached in 5 minutes. The effects of temperature on the extraction and the stoichiometry of the extracted complex were investigated. The extraction of californium(III) was studied and it was found that the BTBP molecule has a higher affinity for californium than for americium (SF_Cf/Am around 4). This system could be used to separate actinides(III) from lanthanide fission products with high efficiency, if used in conjunction with a pre‐equilibrium step.     

Characterization of Extraction of Chromatographic Materials Containing Bis(2‐ethyl‐1‐hexyl)Phosphoric Acid, 2‐Ethyl‐1‐Hexyl (2‐Ethyl‐1‐Hexyl) Phosphonic Acid,and Bis(2,4,4‐Trimethyl‐1‐Pentyl)Phosphinic Acid

Abstract

This work describes the uptake of a wide range of metal ions, including alkaline earths, transition metals, post‐transition metals, lanthanides and actinides, from acidic nitrate and chloride media on extraction chromatographic resins prepared from three different acidic organophosphorus compounds: bis(2‐ethyl‐1‐hexyl) phosphoric acid (HDEHP), 2‐ethyl‐1‐hexyl(2‐ethyl‐1‐hexyl)phosphonic acid, (HEH[EHP]) and bis(2,4,4‐trimethyl‐1‐pentyl)phosphinic acid (H[DTMPP]). The data is plotted in a format allowing for the easy comparison of the uptake of all metal ions under a given condition. Additionally, examples of several novel separations using the three extraction chromatographic materials are discussed.     

Comparison of Hydrometallurgical Parameters of N,N‐Dialkylamides and of Tri‐n‐Butylphosphate

Straight‐chain N,N‐dihexyloctanamide (DHOA) and branched‐chain N,N‐di(2‐ethylhexyl)isobutyramide (D2EHIBA) have been identified as promising alternatives to tri‐n‐butylphosphate (TBP) for the reprocessing of spent uranium based fuels, and selective extraction of ²³³U from irradiated thorium fuels, respectively. The present work deals with the effects of different hydrodynamic parameters such as viscosity, density, and interfacial tension (IFT) on the phase‐separation time (PST) under uranium and thorium loading conditions. The IFT values have been determined under varying experimental conditions such as the aqueous nitric acid concentration, n‐dodecane purity, ligand concentration, and thorium/uranium loading conditions. These studies have suggested that the quality of n‐dodecane affects the IFT values of different solutions. The IFT values of D2EHIBA changed marginally (23.3 ± 0.9 mNm^?1) against THOREX feed solution for the wide range of D2EHIBA concentration (0.1–1.0 M). However, IFT, viscosity, and PST values increased with uranium loading of 1.1 M DHOA. These studies suggested that a lower phase‐disengagement rate with increased uranium loading was mainly due to the increased viscosity of the loaded 1.1 M DHOA solution.     

An Investigation into the Extraction of Americium(III), Lanthanides and D‐Block Metals by 6,6′‐Bis‐(5,6‐dipentyl‐[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridinyl (C5‐BTBP)

Abstract

The tetradentate ligand (C₅‐BTBP) was able to extract americium(III) selectively from nitric acid. In octanol/kerosene the distribution ratios suggest that stripping will be possible. C₅‐BTBP has unusual properties and potentially offers a means of separating metals, which otherwise are difficult to separate. For example C₅‐BTBP has the potential to separate palladium(II) from a mixture containing rhodium(III) and ruthenium(II) nitrosyl. In addition, C₅‐BTBP has the potential to remove traces of cadmium from effluent or from solutions of other metals contaminated with cadmium. C₅‐BTBP has potential as a reagent for the separation of americium(III) from solutions contaminated with iron(III) and nickel(II), hence offering a means of concentrating americium(III) for analytical purposes from nitric acid solutions containing high concentrations of iron(III) or nickel(II).     

Para‐substituted 1‐Phenyl‐3‐methyl‐4‐aroyl‐5‐pyrazolones as Selective Extractants for Vanadium(V) from Acidic Chloride Solutions

Abstract

Para‐substituted 4‐aroyl derivatives of 1‐phenyl‐3‐methyl‐5‐pyrazolones (HX), namely, 1‐phenyl‐3‐methyl‐4‐(4‐fluorobenzoyl)‐5‐pyrazolone (HPMFBP) and 1‐phenyl‐3‐methyl‐4‐(4‐toluoyl)‐5‐pyrazolone (HPMTP) were synthesized and examined with regard to the extraction behavior of multivalent metal ions such as magnesium(II), aluminum(III), titanium(IV), vanadium(V), chromium(III), manganese(II), iron(II), and iron(III) that are present in titania waste chloride liquors. For comparison, studies have also been carried out with 1‐phenyl‐3‐methyl‐4‐benzoyl‐5‐pyrazolone (HPMBP). The results demonstrate that vanadium(V) and iron(III) are extracted into chloroform with 4‐aroyl‐5‐pyrazolones as VO₂X · HX and FeX₃, respectively. On the other hand, magnesium(II), aluminum(III), titanium(IV), chromium(III), manganese(II), and iron(II) were not found to be extracted into the organic phase. The equilibrium constants of vanadium(V) and iron(III) with various 4‐aroyl‐5‐pyrazolones follow the order HPMFBP>HPMBP>HPMTP, which is in accordance with their pKa values. The selectivity between vanadium(V) and iron(III) increases with increasing hydrochloric acid concentration. Further, it is clear from the results that iron(III) is not getting extracted above 1.0 mol dm^?3 hydrochloric acid solution. The electronic and IR spectra of the extracted complexes of vanadium(V) and iron(III) were used to further clarify the nature of the extracted complexes. The potential of these reagents for the selective extraction and separation of vanadium(V) from titania waste chloride liquors has also been discussed.     

6,6′‐Bis(5,5,8,8‐tetramethyl‐5,6,7,8‐tetrahydro‐benzo[1,2,4]triazin‐3‐yl) [2,2′]bipyridine,an Effective Extracting Agent for the Separation of Americium(III) and Curium(III) from the Lanthanides

Abstract

The extraction of americium(III), curium(III), and the lanthanides(III) from nitric acid by 6,6′‐bis(5,5,8,8‐tetramethyl‐5,6,7,8‐tetrahydro‐benzo[1,2,4]triazin‐3‐yl)‐[2,2′]bipyridine (CyMe₄‐BTBP) has been studied. Since the extraction kinetics were slow, N,N′‐dimethyl‐N,N′‐dioctyl‐2‐(2‐hexyloxy‐ethyl)malonamide (DMDOHEMA) was added as a phase transfer reagent. With a mixture of 0.01 M CyMe₄‐BTBP+0.25 M DMDOHEMA in n‐octanol, extraction equilibrium was reached within 5 min of mixing. At a nitric acid concentration of 1 M, an americium(III) distribution ratio of approx. 10 was achieved. Americium(III)/lanthanide(III) separation factors between 50 (dysprosium) and 1500 (lanthanum) were obtained. Whereas americium(III) and curium(III) were extracted as disolvates, the stoichiometries of the lanthanide(III) complexes were not identified unambiguously, owing to the presence of DMDOHEMA. In the absence of DMDOHEMA, both americium(III) and europium(III) were extracted as disolvates. Back‐extraction with 0.1 M nitric acid was thermodynamically possible but rather slow. Using a buffered glycolate solution of pH=4, an americium(III) distribution ratio of 0.01 was obtained within 5 min of mixing. There was no evidence of degradation of the extractant, for example, the extraction performance of CyMe₄‐BTBP during hydrolylsis with 1 M nitric acid did not change over a two month contact.     

Phthalimide‐N‐oxyl (PINO) Radical,a Powerful Catalytic Agent: Its Generation and Versatility Towards Various Organic Substrates

The last two decades represents a “start line” for the worldwide chemists, to develop new oxidizing methods, to replace the “old‐fashioned” ones, which are expensive, pollute the environment, and proceed in harsh conditions. One of the best candidates to satisfy the present global needs is N‐hydroxyphthalimide (NHPI), which can be used as a catalytic reagent successfully in a wide range of organic transformations. In this article, a review of the most frequently used methods to transform the NHPI into its nitroxyl radical correspondent, and the use of this powerful catalytic agent into various organic transformations, are presented.     

Poly(Amide‐Imide)s Based on Amino‐Terminated Oligoimides

Abstract

An amino‐terminated oligoimide was prepared by the Michael addition reaction of ethylene bis‐maleimide (EBM) and 4,4′‐diamnio diphenyl‐sulfone (DDS) at an EBM:DDS molar ratio of 1:2. The poly(amide‐imide)s (PAI)s were prepared by condensation of this EBMDDS oligoimide with various aliphatic bisesters. The resultant PAIs were characterized by elemental analysis, IR spectral studies, and the number average molecular weight estimated by non‐aqueous conductometric titration and thermogravimetry. The curing reaction of an epoxy resin [a diglycidyl ether of bis‐phenol‐A (DGEBA)] with PAIs was monitored by differential scanning calorimetry (DSC). Glass‐ and carbon‐reinforced laminates of PAI‐epoxy resin were also prepared and characterized.