Extraction of Lanthanides(III) from HClO4 Solutions with Bis(diphenylphosphorylmethylcarbamoyl)alkanes

Abstract

Novel polyfunctional neutral organophosphorus compounds, namely bis(diphenylphosphoryl-methylcarbamoyl)alkanes of general formula [Ph₂P(O)CH₂C(O)NH]₂(CH₂)_n (I-III; n = 3, 5, 8), were synthesized and studied as extractants for La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from perchloric acid solutions. The influence of both of HClO₄ concentration in the aqueous phase and that of the extractant in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes has been determined. Bis(diphenylphosphorylmethylcarbamoyl)alkanes II and III possess a higher extraction efficiency towards Ln(III) than their monoanalogue Ph₂P(O)CH₂C(O)NHC₉H₁₉. The potentialities of polymeric resin impregnated with bis(diphenylphosphorylmethylcarbamoyl)pentane II for the preconcentration of lanthanides(III) from perchloric acid solutions are demonstrated.     

Synthesis and Screening of t-Bu-CyMe4-BTBP,and Comparison with CyMe4-BTBP

The effect of adding a t-butyl group to the core molecule of CyMe₄-BTBP, with the aim of improving solubility in organic diluents, has been studied with regard to the extraction of Am(III) and Eu(III) from HNO₃. Synthesis of t-Bu-CyMe₄-BTBP is described in detail. Metal nitrates are extracted from nitric acid in the form of 1:2 complexes, M(NO₃)₃(BTBP)₂. Whether in 1-octanol, kerosene, or cyclohexanone diluents, t-Bu-CyMe₄-BTBP extracts with larger distribution ratios but with slower kinetics than CyMe₄-BTBP. The general trends previously observed for CyMe₄-BTBP regarding the diluent and modifier influence were also found for t-Bu-CyMe₄-BTBP.     

Polymer‐Bound Pyridine‐Bis(oxazoline). Preparation through Click Chemistry and Evaluation in Asymmetric Catalysis

A pyridine‐bis(oxazoline) ligand was efficiently immobilized by copper(I)‐catalyzed azide‐alkyne cycloaddition onto a polystyrene resin. The so obtained click‐pybox resin 1a was associated with various metal salts (YbCl₃, LuCl₃, CuOTf) and the resulting resin‐bound catalysts were explored in ring‐opening of cyclohexene oxide, silylcyanation of benzaldehyde and alkynylation of imines. These new polymer‐supported catalysts exhibit good to excellent performances in terms of catalytic activity, enantioselectivity and recyclability.     

Direct Selective Extraction of Trivalent Americium from PUREX Raffinate Using a Combination of CyMe4BTPhen and TEDGA—A Feasibility Study

The direct and selective extraction of Am(III) from simulated PUREX raffinate is demonstrated using a novel combination of the lipophilic extractant CyMe₄BTPhen (2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenzo[e]-[1,2,4]triazin-3-yl)-1,10-phenanthroline) and the hydrophilic complexant TEDGA (N,N,N’,N’-tetraethyl-diglycolamide) to enhance selectivity toward Am(III) extraction. Separation factors (SF) of up to SF_Am/Cm = 4.9 were observed in tracer experiments using this combination of CyMe₄BTPhen and TEDGA. Distribution ratios of stable isotopes of fission and activation products contained in a simulated PUREX raffinate solution are reported for the first time with CyMe₄BTPhen, and some co-extracted metal ions are identified. The metal ions partly co-extracted from the simulated PUREX raffinate solution were Cu, Pd, Cd, Ag, Ni, and to a lesser extent Sn and Mo. The co-extraction of Pd and Ag was successfully suppressed using Bimet ((2S,2’S)-4,4’-(ethane-1,2-diylbis(sulfanediyl))bis(2-aminobutanoic acid)). The extraction was also studied as a function of the TEDGA concentration. The distribution ratios of Am and Cm can be adjusted by variation of the TEDGA concentration to yield D_Am values >1 and D_Cm values <1. Separation factors for Am(III) over Cm(III) of up to SF_Am/Cm = 2.4 were observed in these experiments. For Ln(III) + Y(III), distribution ratios below 1 were observed, thus enabling a direct extraction of Am(III) from simulated PUREX raffinate with a sufficient selectivity against trivalent lanthanides and Cm(III).     

Extraction Behavior of Ln(III) Ions by T2EHDGA/n-Dodecane from Nitric Acid and Sodium Nitrate Solutions

The diglycolamide extractant T2EHDGA has proven to be promising for the separation of lanthanides and minor actinides in high-level nuclear waste reprocessing. This neutral extractant has shown significant extraction capacity for HNO₃ into the nonpolar organic phase, along with hyper-stoichiometric nitrate dependence on extraction of trivalent f-elements. The transport behavior of T2EHDGA/n-dodecane toward trivalent lanthanides is not well understood. This work found a significant increase in distribution ratios for Eu(III) extracted from aqueous HNO₃ media compared with that from NaNO₃. The extraction of Eu(III) from HNO₃ results in a different thermodynamic product than predicted by classic solvent extraction of 3:1 ligand–metal complex as observed with NaNO₃ in FTIR and UV-vis spectroscopy. Experimental distribution measurements in conjunction with mass-action modeling using the solvent extraction modeling program SXLSQI suggest participation of 1 to 2 HNO₃ molecules in the Eu(III)/T2EHDGA complex upon extraction from HNO₃ media, indicative of a mechanism change responsible for the enhanced extraction behavior toward lanthanides in the presence of HNO₃.     

Cooperative effect of 2-(dibutylcarbamoyl)benzoic acid and 2-thenoyltrifluoroacetone for the synergistic extraction of lanthanide ions

2-(Dibutylcarbamoyl)benzoic acid (HL) has been examined for the extraction-separation of La³⁺, Eu³⁺ and Er³⁺ from aqueous chloride solutions into organic diluents; dichloromethane, ethylacetate and carbon tetrachloride. The efficiency and the selectivity of the extraction process were significantly affected by the organic diluent. The application of a mixture of HL and 2-thenoyltrifluoroacetone (HTTA) showed a synergistic effect on the extraction of the studied lanthanides. The extracted species was found to be as ML₃(HTTA) complexes (M is La³⁺, Eu³⁺ and Er³⁺). The proposed method was applied for the extraction of lanthanides from simulated leach solution of spent Ni-MH batteries.     

Tuning Cerium(IV)‐Assisted Hydrolysis of Phosphatidylcholine Liposomes under Mildly Acidic and Neutral Conditions

With the goal of designing a lysosomal phospholipase mimic, we optimized experimental variables to enhance Ce^IV‐assisted hydrolysis of phosphatidylcholine (PC) liposomes. Our best result was obtained with the chelating agent bis–tris propane (BTP). Similar to the hydrolytic enzyme, Ce^IV‐assisted hydrolysis of PC phosphate ester bonds was higher at lysosomal pH (～4.8) compared to pH 7.2. In the presence of BTP, the average cleavage yield at ～pH 4.8 and 37 °C was: 67±1 %, 5.7‐fold higher than at ～pH 7.2 and roughly equivalent to the percent of phospholipid found on the metal‐accessible exo leaflet of small liposomes. No Ce^IV precipitation was observed. When BTP was absent, there was significant turbidity, and the amount of cleavage at ～pH 4.8 (69±1 %) was 2.1‐fold higher than the yield obtained at ～pH 7.2. Our results show that BTP generates homogenous solutions of Ce^IV that hydrolyze phosphatidylcholine with enhanced selectivity for lysosomal pH.     

Tuning red-green-white up-conversion color in nano NaYF_4:Er/Yb phosphor

The possibility of tuning between red,green and broadband white color of up-conversion was demonstrated in thermally 450 oC treated Yb/Er co-doped nano NaYF4 phosphor.The color variability was studied by means of power dependence of luminescence,which ex-hibited unusual behavior.Large hysteresis,as well as discrepancy from a power law indicated the important role the increased heating played during the up-conversion in nano-sized materials.     

Luminescence properties of Tm^3＋/Yb^3＋, Er^3＋/Yb^3＋ and Ho^3＋/Yb^3＋ activated calcium tungstate

CaWO4 phosphor activated by the Tm3+/Yb3+,Er3+/Yb3+ and Ho3+/Yb3+ ions were synthesized by a traditional high-temperature solid-state method.The crystal structures and morphologies of the products were characterized by X-ray powders diffraction method(XRD) ,infrared spectra(FT-IR) and scanning electron microscopy(SEM) .The samples were found to show up-conversion luminescence properties.CaWO4 doped with Tm3+/Yb3+ showed blue luminescence characteristic of Tm(III) ion in the range of 460-485 nm,corresponding to the 1G4→3H6 electronic transition.CaWO4 doped with Er3+/Yb3+ showed strong green luminescence at 510-565 nm(2H11/2,4S3/2→4I15/2) and weak red luminescence at 640-685 nm(4F9/2→4I15/2) of Er(III) ion.CaWO4 doped with Ho3+/Yb3+ phosphor emitted green luminescence at 525-560 nm(5S2,5F4→5I8) and red luminescence at 630-670 nm(5F5→5I8) and at 730-770 nm(5S2,5F4→5I7) ,which is the characteristic of Ho(III) ion.