Neutral Organophosphorus Compounds Research Articles

Solvent extraction of lithium from ammoniacal solution using thenoyltrifluoroacetone and neutral ligands

Lithium extraction from ammoniacal solution with thenoyltrifluoroacetone (HTTA) and neutral ligand was studied in various organic solvents. The remarkable enhancement of lithium extraction was observed by the addition of neutral organophosphorus compounds and the experiments showed that trioctylphosphine oxide(TOPO) was preferable for lithium extraction. The synergistic effect of thenoyltrifluoroacetone and trioctylphosphine was studied in detail and the results indicated that the strongest enhancement coefficient was 1205 when molar ratio of two extractants was 1:1. The extracted lithium complex was found to be Li•TTA•2TOPO by slope method and the results of thermodynamic study indicated that the extraction process was spontaneous exothermic process and the degree of disorder increased after extraction. In addition, stripping and regeneration condition of organic phase were investigated in detail. It was demonstrated that the synergistic extraction system containing HTTA and TOPO could effectively separate lithium and other alkali metal ions and was feasible for lithium extraction from ammoniacal solution.

Radiolysis products and degradation mechanism studies on di-1-methyl heptyl methyl phosphonate

Di-1-methyl heptyl methyl phosphonate (DMHMP) is a promising alternative extractant for Th-U fuel reprocessing, in which the irradiation stability of extractant should be systematically studied. In this paper, the radiolysis products of DMHMP were analyzed qualitatively and quantitatively with gas and ion chromatograph, the possible radiolysis mechanism of DMHMP was also concluded. Moreover, the effect of structure on the radiolysis products and irradiation stability of neutral organophosphorus compound extractant was also discussed.

Solvent extraction of scandium from lateritic nickel- cobalt ores using different organic reagents

Scandium is the most important and strategic metal that can be recovered as a by-product from lateritic nickel-cobalt ores. In this research, different extractants were investigated in order to extract scandium from a sulfate medium by a using a solvent extraction method. Generally, the organic extractants are classified as acidic, neutral and basic organophosphorus compounds. However, in solvent extraction of scandium, the acidic and neutral organophosphorus compounds are preferred due to their higher extraction efficiencies. Thus, the aim of the present study was to compare the scandium extraction efficiencies of some acidic and neutral organic reagents. For this reason, Ionquest 290 (Bis(2,4,4-trimethylpenthyl) phosphonic acid), DEHPA (Di(2-ethylhexyl) phosphoric acid), Cyanex 272 ((Bis(2,4,4-trimethylpentyl) phosphinic acid) which are acidic organophosphorus compounds, and Cyanex 923 (Trialkylphosphine oxide), which is a neutral organophosphorus compound, were used. The extraction capacities of these organics were studied with respect to the extractant concentration at same pH and phase ratio. As a result of the study, DEHPA was found to have higher scandium extraction efficiency with lower iron extraction at pH = 0.55 at a phase ratio of 10:1 = A:O.

Extraction Properties of 1,2,3-Triazole Modified Carbamoylmethylphosphine Oxide in Nitric Acid Media

A novel polyfunctional neutral organophosphorus compound, 2-(diphenylphosphoryl)-N,N-diethyl-3-(1-phenyl-1H-1,2,3-triazol-4-yl)propanamide (I), was synthesized and studied as an extractant for Pd(II), Ln(III), U(VI), and Th(IV) from HNO3 solutions. The influence of aqueous and organic phases on the extraction efficiency was elucidated and stoichiometry of the complexes extracted was determined. The introduction of a 1,2,3-triazole fragment into the methylene bridge of diphenyl(diethylcarbamoylmethyl)phosphine oxide resulted in a considerable increase of the efficiency of Pd(II) extraction. The potentialities of carbon nanotubes impregnated with compound I for the preconcentration of Pd(II) from nitric acid solutions are demonstrated. The introduction of a 1,2,3-triazole fragment into the methylene bridge of a CMPO molecule does not essentially change the extraction efficiency of compound I towards U(VI) and Ln(III) but drastically decreases the Th(IV) extraction and change the order in the extractactability of U(VI) and Th(IV) with this compound from HNO3 solutions.

Ruthenium sorption as heterometallic complexes with phosphoryl-containing impregnated sorbents

It is shown that the main features of ruthenium extractive recovery with neutral organophosphorus compounds (L) as [RuNO(NO2)4MLn] (M = Zn, Cu, Co, Ni; n = 2–3) heterometallic complexes are retained on the sorption recovery with sorbents impregnated with L. The sorbent based on mixed trialkylphosphine oxide can be used for the chromatographic recovery of ruthenium, the extent of total ruthenium recovery at sorption-desorption stages (90–94%) retains after seven cycles.

Extraction Properties of P(O)-Modified N-Aryl-Carbamoylmethylphosphine Oxides in Nitric Acid Media

Novel polyfunctional neutral organophosphorus compounds, P(O)-modified N-aryl- carbamoylmethylphosphine oxides, Ph2P(O)CH2C(O)NH-(o-C6H4)(CH2)n-P(O)Ph2 and Ph2P(O)CH2C(O)NH-(m-C6H4)(CH2)n-P(O)Ph2 (n = 1,2), were synthesized and studied as extractants for U(VI), Th(IV) and Ln(III) from HNO3 solutions. The influence of aqueous and organic phases on the extraction efficiency was elucidated and stoichiometry of the complexes extracted was determined. Introduction of an additional phosphoryl group into the phenyl substitutent at the nitrogen atom of diphenyl(N-phenylcarbamoylmethyl)phosphine oxide resulted in an increase of the efficiency of U(VI), Th(IV), Ln(III), and Re(VII) extraction.

Effect of the structure of bidentate neutral organophosphorus compounds on the extraction of Sr(II) from aqueous solutions in the presence of ionic liquids

The extraction of microamounts of Sr(II) from aqueous solutions with solutions of bidentate neutral organophosphorus compounds is considerably enhanced in the presence of ionic liquids. The efficiency of the Sr(II) extraction varies in a wide range depending on the nature of the coordinating groups in the extractant molecule, substituents at the P and N atoms, and structure of the fragment linking the coordinating groups.

1,3-Bis[(diphenylphosphorylacetamido)methyl]benzene as reagent for extraction and sorption preconcentration of REE(III), U(VI), and Th(IV) from nitric acid solutions

The extraction of microamounts of REE(III), U(VI), and Th(IV) from HNO3 solutions in the form of complexes with a polyfunctional neutral organophosphorus compound, 1,3-bis[(diphenylphosphorylacetamido)-methyl]benzene, was studied. The influence exerted by the structure of the bridge binding two carbamoylmethyl-phosphine oxide fragments on the efficiency of the extraction of REE(III), U(VI), and Th(IV) and on the stoichiometry of the extractable complexes was analyzed. The possibility of recovering and concentrating REE(III), U(VI), and Th(IV) from nitric acid solutions with a complexing sorbent prepared by noncovalent immobilization of 1,3-bis[(diphenylphosphorylacetamido)methyl]benzene on the surface of carbon nanotubes was examined.

Extraction of scandium and rare-earth elements by a phosphorylated azapodand

The interphase distribution of microamounts of nitrates and perchlorates of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu between aqueous solutions of NH4NO3 or NH4ClO4 and solutions of a phosphorylated podand [Ph2P(O)CH2CH2OCH2CH2]2NBu in dichloroethane was studied. The stoichiometry of extracted complexes was determined. The efficiency of metal ion transfer to an organic phase was considered as affected by HClO4, HNO3, and HCl concentrations in the aqueous phase and by the nature of the organic solvent. The test compounds have higher extraction capacities with respect to metal ions than neutral monodentate organophosphorus compounds.

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

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.

SANS Study of HCl Extraction by Selected Neutral Organophosphorus Compounds in n-Octane

The extraction of HCl by tri(2-ethylhexyl) phosphate (TEHP), tri-n-octyl phosphate (TOP), and tri-n-octylphosphine oxide (TOPO) in n-octane was investigated by liquid-liquid distribution of acid and water and small-angle neutron scattering (SANS) measurements. No formation of a heavy organic phase (third phase) was observed with TEHP and TOP under the experimental conditions used, whereas for 0.4 M TOPO the HCl limiting organic concentration (LOC) at 23°C was 0.32 M (with 5.1 M HCl in the equilibrium aqueous phase). For higher HCl concentrations in the aqueous phase, the organic phase splits into a light and a heavy layer. For TEHP and TOP, the SANS results, interpreted using the Baxter model for hard spheres with surface adhesion, indicated the formation of only small reverse micelles with little intermicellar attraction. For TOPO, the scattering signals suggested the formation of much larger and strongly interacting micelles. The critical values of the stickiness parameter, τ−1, and the interaction potential energy, U(r), for the LOC sample in the TOPO system were consistent with the model for third-phase formation previously developed for tri-n-butyl phosphate (TBP). According to this model, organic phase splitting is due to van der Waals interactions between the polar cores of reverse micelles formed by the extractants in the organic phase.

Extraction and sorption preconcentration of U(VI) and Th(IV) from nitric acid solutions using bis(diphenylphosphorylmethylcarbonylamino)alkanes

Extraction of microamounts of U(VI) and Th(IV) from HNO3 solutions in the form of complexes with polyfunctional neutral organophosphorus compounds, bis(diphenylphosphorylmethylcarbonylamino)alkanes [Ph2P(O)CH2C(O)NH]2(CH2)n (n = 3, 5, 8), was studied. The influence of the extractant structure on the efficiency and selectivity of the extraction of U(VI) and Th(IV) was examined, and the stoichiometry of the extractable complexes was determined. The examined compounds exhibit higher extraction ability and selectivity to metal ions in HNO3 solutions, compared to the alkylamide Ph2P(O)CH2C(O)NHC9H19. The possibility of selective recovery and preconcentration of U(VI) and Th(IV) from nitric acid solutions with a complexing sorbent prepared by noncovalent immobilization of bis(diphenylphosphorylmethylcarbonylamino)pentane on a macroporous polymeric matrix was demonstrated.

Linear alkylbenzene (LAB) as diluent for extractants. Extraction of rare-earth elements with solutions of neutral organophosphorus compounds in LAB

Extraction of REE with solutions of neutral organophosphorus compounds (TBP, TIAP, DIOMP) in a new diluent, linear alkylbenzene (LAB), was studied. LAB exhibits significant advantages over known diluents: high flash point (+147°C), nontoxicity, absence of odor, low cost, availability, and good compatibility with polymeric structural materials. LAB is well compatible with TBP, TIAP, and DIOMP. Extraction of HNO3 and REE nitrates is not accompanied by precipitation of extractable complexes or by formation of a second organic phase in a wide concentration range, up to saturation of the extractant. The major extractable complex in extraction of REE nitrates is Ln(NO3)3·3NOPC, where NOPC = TBP, TIAP. The main parameters of extraction systems (distribution ratios, separation factors) with LAB are similar to those of the related systems with paraffin hydrocarbons as diluents. Experiments on group separation of REEs on a 56-step extraction installation gave results agreeing with the calculation data.

Extraction of Lanthanides(III) from Aqueous Nitrate Media with Tetra‐(p‐tolyl)[(o‐Phenylene)Oxymethylene] Diphosphine Dioxide

A novel tridentate neutral organophosphorus compound, tetra‐(p‐tolyl)[(o‐phenylene)oxymethylene] diphosphine dioxide (I) has been synthesized and its extracting ability for microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO3 and NH4NO3 aqueous 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 and conditional extraction constants of Ln(III) have been determined. The extraction behavior of compound I is compared with that of the diglycolamide ligand TODGA. The potentialities of polymeric resin impregnated with compound I for the preconcentration of lanthanides(III) from nitric acid solutions are demonstrated.

Extraction methods in development of Gd-loaded liquid organic scintillators for antineutrino detection: 2. Scintillators based on solutions of gadolinium 2-methylvalerate

Complexes of Gd with carboxylic acids C4–C9 were prepared, and their properties were studied: solubility in water and organic solvents in relation to temperature, melting points, and decomposition points. A procedure was developed for removing water from gadolinium 2-methylvalerate Gd(2MVA)3 to a final content not exceeding 0.01%. To increase the solubility of Gd(2MVA)3 in low-polarity organic solvents and to stabilize the resulting organic solutions, it was suggested to add extractants such as 2-methylvaleric acid (H2MVA) or neutral organophosphorus compounds: triisoamylphosphine oxide (TIAPO) or trioctylphosphine oxide (TOPO). Liquid Gd-loaded organic scintillators based on Gd(2MVA)3 solutions with additions of H2MVA, TIAPO, and TOPO in trimethylbenzene (TMB), phenylxylylethane (PXE), and their mixtures with dodecane were prepared. Long-term tests (up to 2 years) of the stability of the optical properties of the scintillators obtained proved their stability at temperatures of up to 30°C. At elevated temperatures (40°C and higher), the scintillators degrade. The previously made suggestion that water in the scintillator negatively affects its optical properties in prolonged storage was confirm

Extraction of rare-earth elements from nitric acid solutions with bidentate neutral organophosphorus compounds in the presence of l-butyl-3-methylimidazolium hexafluorophosphate

The distribution of microamounts of La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between aqueous HNO3 solutions and solutions of tetraphenylmethylenediphosphine dioxide, diphenyl(diethylcarbamoylmethyl)phosphine oxide, and dibutyl(diethylcarbamoylmethyl)phosphine oxide in organic solvents in the presence of l-butyl-3-methylimidazolium hexafluorophosphate (BMImPF6) was studied. The stoichiometry of the extractable complexes was determined. The influence of the HNO3 concentration and the nature of the extractant and organic solvent on the synergistic effect observed in the REE extraction in the presence of BMImPF6 in the organic phase was analyzed. The possibility of using a macroporous polymeric sorbent impregnated with a mixture of tetraphenylmethylenediphosphine dioxide and BMImPF6 for the recovery of REE(III), U(VI), and Th(IV) from HNO3 solution was demonstrated.

Effect of ionic liquids on the extraction of rare-earth elements by bidentate neutral organophosphorus compounds from chloride solutions

The partition of microamounts of lanthanide chlorides (Ln = La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y) between aqueous HCl and organic solutions of tetraphenylmethylenediphosphine dioxide, diphenyl(diethylcarbamoylmethyl)phosphine oxide, and dibutyl(diethylcarbamoylmethyl)phosphine oxide was studied in the presence of ionic liquids (ILs): 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The stoichiometry of extracted complexes was determined. The effect of the aqueous HCl concentration, the nature of the extractant, and the organic diluent on the efficiency of lanthanide extraction was studied.

Anomalous effects in extraction of lanthanides and actinides with bidentate neutral organophosphorus extractants. Role of proton hydrate solvates

Extraction of europium, lithium, and acids from nitric acid and perchloric acid media with solutions of bidentate neutral organophosphorus compounds (BNOPCs) in polar diluents (dichloroethane, meta-nitrobenzotrifluoride, and trifluoromethyl phenyl sulfone) was studied. It was found that cationic complexes of BNOPCs with proton hydrates or lithium cation are formed in the organic phase. BNOPC hydrate solvates H+ · nH2O · mBNOPC extract europium substantially better than do free BNOPCs. The main differences of BNOPCs from monodentate extractants are anomalous aryl effect (AAE) and perchlorate and synergic (the latter is observed in the presence of chlorinated cobalt dicarbollide) effects, which are connected with specific properties of proton hydrate solvates with BNOPC. The existence of BNOPC cationic complexes found by IR spectroscopy in polar diluents was confirmed by ESI-MS. The effect of preorganization of the extractant molecule and the change from the solvate mechanism of the metal ion extraction to the cation-exchange mechanism are apparently responsible for the high extraction ability of proton hydrate solvates with BNOPCs.

Cross-sensitive rare-earth metal sensors based on bidentate neutral organophosphorus compounds and chlorinated cobalt dicarbollide

A variety of new chemical sensors (ion selective electrodes) for determination of rare-earth (RE) and trivalent metal cations such as yttrium(III), lanthanum(III), praseodymium(III), neodymium(III) and europium(III) that are commonly present in aqueous radiological samples, e.g. in high-level liquid waste (HLW) and solutions from reprocessing spent nuclear fuel, have been developed and studied. The sensors are based on bidentate neutral organophosphorus compounds, such as methylene bridged diphosphine dioxides and carbamoylmethylphosphine oxides, which are efficient extractants, especially when used in conjunction with chlorinated cobalt dicarbollide, for recovery and concentration of the RE and actinide elements from acidic HLW derived from the nuclear fuel cycle. The sensors exhibit remarkable sensitivity to RE cations and indicate promise for HLW analysis.

Radiation resistance of a series of organophosphorus extractants

Extraction of U(VI), TUE, and REE from acid process solution with solutions of mono-and bidentate neutral organophosphorus compounds (NOPCs), phenyloctyl(N,N-diisobutylcarbamoylmethyl)phosphine oxide (CMPO), 2-ethylhexyl (N,N-dibutylcarbamoylmethyl)phenylphosphinate (CMPP), and unsymmetrical phosphine oxide (UPO) was studied as influenced by γ-irradiation at different absorbed dose rates. In all cases extraction of the target radionuclides decreased with increasing absorbed dose of γ-radiation. The resistance of the NOPCs to radiolysis decreases as CMPO>CMPP>UPO owing to the difference in the structures of their molecules.