Trialkylphosphine Oxide Research Articles

Microstructure and performance studies of (Mo, Ru, Pd, Zr) tetra-doped gadolinium zirconate pyrochlore

ABSTRACTProper disposal of nuclear waste with multi-nuclides and multi-valence is still challenge. A series of (Mo, Ru, Pd, Zr) tetra-doped Gd2Zr2O7 ceramics were studied to understand the microstructure and performance evolution of nuclear waste forms that immobilised simulated waste after trialkyl phosphine oxides (TRPO) process. The structure of as-obtained samples were tested by X-ray diffraction, Raman, scanning electron microscope, electron back-scattered diffraction, and energy-dispersive X-ray spectroscopy, while the mechanical and chemical performance were characterised by Vickers hardness and aqueous leaching method. The results indicate that the mechanical behaviour are closely linked with the phase structure, and the highest Vickers hardness is obtained at the phase turning point. The leaching results show that the normalised leaching rate (LR) of the doped elements decrease in the order of Mo, Ru, Pd, Zr. After reaching equilibrium, their LR are as low as 4.12 × 10−4 g·m−2·d−1, 1.50 × 10−5 g·m−2·d−1, 1.30 × 10−5 g·m−2·d−1, and 2.09 × 10−7 g·m−2·d−1, respectively.

Manganese extraction with mixtures of bis(2,4,4-trimethylpentyl)dithiophosphinic acid and trioctyl phosphine oxide

ABSTRACTIt was shown that a strong synergistic effect (S ≈ 4000) takes place when extracting manganese (II) from sulfate solutions with mixtures of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (CYANEX 301) and trioctyl phosphine oxide (TOPO. The synergistic effect is caused by the formation of the mixed complex Mn-HR-TOPO. Analysis of the manganese partition between organic and aqueous phase as well as of the IR and electron paramagnetic resonance spectra of the extracts showed that manganese forms a hexacoordinated complex with the dithiophosphinate ions and TOPO with an octahedral geometry. The composition of the complex can be presented as MnR2∙2TOPO.Examples of the possible use of the CYANEX 301 and trialkyl phosphine oxide (TAPO, CYANEX 923) mixtures when processing manganese-containing liquors are given.

Cooperative Reinforcement of Ionic Liquid and Reactive Solvent on Enzymatic Synthesis of Caffeic Acid Phenethyl Ester as an In Vitro Inhibitor of Plant Pathogenic Bacteria.

It is widely believed that lipases in ionic liquids (ILs) possess higher enzyme activity, stability and selectivity; however, reaction equilibrium is always limited by product inhibition, and the product is difficult to separate from non-volatile ILs using distillation. To solve this problem, using trialkylphosphine oxide (TOPO) as a complexing agent, a novel biphase of reactive solvent and IL was firstly reported for caffeic acid phenethyl ester (CAPE) production from methyl caffeate (MC) and 2-phenylethanol (PE) catalyzed by lipase via transesterification. The effects of the reaction parameters and their action mechanism were investigated, and the inhibition of CAPE against bacterial wilt pathogen Ralstonia solanacearum was firstly measured. The MC conversion of 98.83% ± 0.76% and CAPE yield of 96.29% ± 0.07% were obtained by response surface methodology in the 25 g/L TOPO-cyclohexane/[Bmim][Tf2N] (1:1, v/v); the complex stoichiometry calculation and FTIR spectrum confirmed that the reversible hydrogen-bond complexation between TOPO and caffeates significantly enhances the cooperative effect of two phases on the lipase-catalyzed reaction. The temperature was reduced by 14 °C; the MC concentration increased by 3.33-fold; the ratio of catalyst to donor decreased by 4.5-fold; and Km decreased 1.08-fold. The EC50 of CAPE against R. solanacearum was 0.17–0.75 mg/mL, suggesting that CAPE is a potential in vitro inhibitor of plant pathogenic bacteria.

Direct synthesis of phosphonium salts and trialkylphosphine oxides

Direct synthesis of phosphonium salts and trialkylphosphine oxides

Targeting fluorescent lamp waste for the recovery of cerium, lanthanum, europium, gadolinium, terbium and yttrium

Owing to the ever-growing demand and supply problems, rare earth elements (REEs) are now considered to be some of the most critical elements. This has focused attention towards their recovery from end-of-life products and industrial waste streams. A hydrometallurgical approach was carried out to assess the recycling potential of REEs from fluorescent lamp waste. In comparison to other efforts in this field, these investigations were carried out using real waste samples originating from a discarded lamp processing facility. Leaching of metals from the waste was studied using nitric, hydrochloric, sulphuric and methane sulphonic acid solutions. Separation of REEs from nitric acid media was investigated using solvent extraction. Batch extraction experiments were carried out using Cyanex 923, a commercial mix of trialkylphosphine oxides. Separation of heavier REEs (terbium, europium and gadolinium) and yttrium from lighter REEs (cerium and lanthanum) is possible due to larger separation factors. Selective stripping of REEs from the co-extractable species (iron and mercury ions) was easily achieved using 4 M hydrochloric acid. Further recovery of the extracted iron and mercury, with either oxalic acid or nitric acid solutions, allows for the subsequent re-use of the organic phase in the process.

Synergistic extraction of zinc from ammoniacal solutions using a β-diketone mixed with trialkylphosphine oxide

A simple comparative study of synergistic extraction of zinc from ammonium sulfate and ammonium chloride systems with mixtures of Mextral54-100 and tri-n-alkylphosphine oxide (TRPO) dissolved in n-heptane was described. Various parameters affecting the extraction process were investigated. Experimental results show that extraction from ammonium sulfate is better than that from ammonium chloride under the same conditions owing to the additional complexation between zinc and chloride ions. Total ammonium concentration and pH have a significant effect on zinc extraction efficiency because of the formation of zinc ammine complexes. The synergistic effect is explained by the formation of adduct between zinc chelates and trialkylphosphine oxide. The thermodynamic data show that the extraction reaction is exothermic and stripping is endothermic. Infrared (IR) spectra of the zinc-loaded organic phases were also examined.

F-Element coordination and extraction selectivity of a carbamoylmethylphosphine oxide ligand based on a tripodal phosphine oxide scaffold

We report here the synthesis and study of a multipodal ligand bearing three CMPO units attached to a trialkylphosphine oxide cap along with the resultant Ln3+, Th4+ and UO22+ metal complexes. This tripodal ligand demonstrates extraction efficiencies of 47% and 44% for the actinide species Th(NO3)4 and UO2(NO3)2 out of 1M nitric acid into a solution of dichloromethane, while all lanthanide nitrates were extracted with relatively low efficiencies. Further extraction studies utilizing 5M nitric acid solutions resulted in nearly quantitative actinide extraction. The ability of this ligand to sensitize the metal-centered luminescence of Eu3+ and Tb3+ in DMSO solutions was also investigated. Finally, possible conformations for the structure of the [La(NO3)-ligand]2+ complex were calculated using density functional theory.

Effect of Hydrogen Bonding to Water on the31P Chemical Shift Tensor of Phenyl- and Trialkylphosphine Oxides and α-Amino Phosphonates

The effect of hydrogen bonding to water on the 31P NMR chemical shift tensor in the titled compounds has been studied experimentally and simulated theoretically using the DFT-GIAO approach. It has been shown that the effect of hydrogen bonding on the 31P NMR parameters of trialkylphosphine oxides can be simulated at the GIAO-B3LYP/cc-pVDZ approximation. The influence of molecular conformation on the NMR parameters is small in these compounds. In contrast, the effect of molecular conformation can totally mask the effect of hydrogen bonding in the case of phenylphosphine oxides. The limiting case is a hydrogen bond with water. In these compounds the DFT-GIAO approach can be useful for the analysis of stronger hydrogen bonds only. The GIAO-B3LYP/cc-pVDZ approximation fails to reproduce the 31P NMR parameters of α-amino phosphonates. Thus, a combination of 31P NMR and low-cost calculations can be used especially effectively in the study of noncovalent interactions in polycrystalline and noncrystalline materials based on trialkylphosphine oxides. The described research strategy is applicable to the study of the local chemical structures in amorphous materials, at surfaces, and in interfaces.

Efficient separation of copper and nickel from ammonium chloride solutions through the antagonistic effect of TRPO on Acorga M5640

In this study, copper and nickel in ammoniacal/ammonium chloride solutions were separated by using an extractant mixture of Acorga M5640 and trialkylphosphine oxide (TRPO). The effects of contact time, Acorga M5640 concentration, modifier concentration, total ammonia concentration, and phase ratio on the extraction and separation of both metals were determined. The addition of TRPO into Acorga M5640 organic phase exerted antagonistic effects on copper and nickel extractions. The antagonistic effect of the extractant mixture was significantly stronger on the extraction of nickel than on that of copper. More than 99.96% of copper and less than 6.6% of nickel were extracted using a mixture of 10vol.% Acorga M5640 and 2vol.% TRPO in kerosene from an ammoniacal solution initially containing 3.0g/L each of copper and nickel under optimal extraction conditions. The separation factor of copper over nickel reached 35,250.

A hydrometallurgical process for the recovery of rare earth elements from fluorescent lamp waste fractions

Rare earth elements (REEs) are presently regarded to be some of the most critical elements, being essential in future sustainable applications. One of the many examples is fluorescent lighting, which relies on REEs such as cerium, europium, gadolinium, lanthanum, terbium and yttrium. The high demand for REEs, low supply, price fluctuations and geopolitical factors have contributed to an increased interest in reclaiming these elements from end-of-life products. This publication reports on a new potential hydrometallurgical route to reclaim REEs in fluorescent lamp waste. The investigations were carried out at bench scale and laboratory pilot scale to assess the potential of a process based on leaching and solvent extraction. Real waste fractions of various compositions, originating from several companies that use different mechanical, physical and chemical processes to treat lamps, were studied. A multi-step leaching process that selectively dissolves different groups of metals in the waste was investigated. Removal of mercury, one of the vital constituents of fluorescent lamps and an undesired contaminant in the waste, was carried out using leaching with iodine in potassium iodide solutions. Selective leaching of impurity metals e.g. calcium and selective leaching of REEs was performed with nitric acid, taking advantage of the significant differences in their leaching kinetics. Separation of REEs was achieved with Cyanex 923, a commercial mix of trialkylphosphine oxides, in a counter-current mixer setter system comprising three extraction and four stripping stages, respectively. The product, a yttrium/europium concentrate, was treated with oxalic acid, followed by thermal treatment, to produce an oxide containing 99.96% REEs, of which 94.61% was yttrium and 5.09% was europium.

Extraction of mid-heavy rare earth metal ions from sulphuric acid media by ionic liquid [A336][P507

In the present study, bifunctional ionic liquid extractant (bif-ILE) [A336][P507] was used in the extraction of mid-heavy rare earths metals (REs) from H2SO4 media. The investigation showed that the distribution ratios (D) of REs enhanced with the increase in equilibrium pH, extractant concentration, and the temperature, but decreased with the increase in the concentration of Na2SO4. A possible extraction stoichiometry was obtained. The thermodynamic functions ΔGo, ΔSo and ΔHo were calculated according to Van't Hoff equation. The results from the comparative test showed that the acidity range was different for [A336][P507], Cyanex 923 (mixture of four trialkylphosphine oxides), tributyl phosphate (TBP) and di-(1-methylheptyl)methyl phosphate (P350). The ionic liquid (IL) [A336][P507] had high extractability from solutions of pH 3.5–5.5. This extraction system was used to extract mid-heavy REs in a simulated leach liquor of ion-adsorbed type rare-earth ore. Moreover, there were enhanced effects for REs extraction when NaCl or NaNO3 was added as a salting-out agent of the simulated leach liquor.

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.

A trialkyl phosphine oxide functionalized task specific ionic liquid for actinide ion complexation: extraction and spectroscopic studies

A trialkylphosphine oxide functionalized task specific ionic liquid (PO-TSIL) with a NTf2− counter anion was synthesized and evaluated for the extraction of actinide ions such as UO22+ and Pu4+ from acidic feed solutions.

ChemInform Abstract: Catalytic Nucleophilic Fluorination by an Imidazolium Ionic Liquid Possessing Trialkylphosphine Oxide Functionality.

AbstractA series of different fluorine‐substituted compounds is synthesized by fluorination of primary alkyl mesylates using a new alkylmethylimidazolium ionic liquid as effective catalyst.

Mixed Monofunctional Extractants for Trivalent Actinide/Lanthanide Separations: TALSPEAK-MME

The basic features of an f-element extraction process based on a solvent composed of equimolar mixtures of Cyanex-923 (a mixed trialkyl phosphine oxide) and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) extractants in n-dodecane are investigated in this report. This system, which combines features of the TRPO and TALSPEAK processes, is based on co-extraction of trivalent lanthanides and actinides from 0.1 to 1.0 M HNO3 followed by application of a buffered aminopolycarboxylate solution strip to accomplish a Reverse TALSPEAK selective removal of actinides. This mixed-extractant medium could enable a simplified approach to selective trivalent f-element extraction and actinide partitioning in a single process. As compared with other combined process applications in development for more compact actinide partitioning processes (DIAMEX-SANEX, GANEX, TRUSPEAK, ALSEP), this combination features only monofunctional extractants with high solubility limits and comparatively low molar mass. Selective actinide stripping from the loaded extractant phase is done using a glycine-buffered solution containing N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA) or triethylenetetramine-N,N,N’,N’’,N’’’,N’’’-hexaacetic acid (TTHA). The results reported provide evidence for simplified interactions between the two extractants and demonstrate a pathway toward using mixed monofunctional extractants to separate trivalent actinides (An) from fission product lanthanides (Ln).

Continuous running test of the solvent extraction separation of Mo and W by H2O2-complexation with TRPO/TBP

An unusual multi-stage extraction and stripping continuous running test was carried out in a mixer-settler. The test of the solvent extraction separation of molybdenum (Mo) and tungsten (W) from ammonium tungstate solution containing high content of Mo was carried out by using a mixture of tri-alkyl phosphine oxide (TRPO) and tributyl phosphate (TBP) as extractant, hydrogen peroxide (H2O2) as complex agent and ammonium bicarbonate (NH4HCO3) solution as stripping agent. According to the effect of pH distribution and storage time on extraction and the poor phase separation of the stripping system, the improvements such as acid addition into middle one stage of extraction, 2-section countercurrent extraction and 2-section concurrent stripping were proposed in order to improve the Mo/W separation effect and phase separation property. The ammonium paratungstate (APT) product was prepared by evaporating crystallization from the 2nd-section raffinate. The continuous running test had successfully and continuously run for more than 98h. The results indicated that the system was very stable and the separation property good. The Mo/WO3 (mass ratio) in the 2nd-section raffinate was less than 1×10−4 under optimal conditions using the aqueous solution containing 110–150g/L WO3 and Mo/WO3 (mass ratio) 10%–15%. The APT product could meet the requirement of 0 grade of APT of the national standards GB/T 10116-2007 of China.

Extraction Studies of Lanthanum(III) from Sodium Salicylate Medium Using Trialkyl Phosphine Oxide

Cyanex-923, a mixture of four trialkylphosphine oxide has been used for the extraction and separation of La(III) from sodium salicylate medium. Lanthanum(III) ion was found to be quantitatively extracted with Cyanex-923 in toluene at pH 6.0. The metal loaded organic phase is stripped with 2.0M HCl solution. Various parameters like effect of pH, Cyanex-923 concentration, sodium salicylate concentration, diluents, equilibration period and stripping agent on the extraction of La(III) has been studied. The stoichiometry of the extracted species of this metal ion was determined on the basis of the slope analysis method. The reaction proceed by solvation and the probable extracted species found were LaSal-HSal .2Cyanex-923.

Extraction Studies of Lanthanum(III) from Sodium Salicylate Medium Using Trialkyl Phosphine Oxide

Cyanex-923, a mixture of four trialkylphosphine oxide has been used for the extraction and separation of La(III) from sodium salicylate medium. Lanthanum(III) ion was found to be quantitatively extracted with Cyanex-923 in toluene at pH 6.0. The metal loaded organic phase is stripped with 2.0M HCl solution. Various parameters like effect of pH, Cyanex-923 concentration, sodium salicylate concentration, diluents, equilibration period and stripping agent on the extraction of La(III) has been studied. The stoichiometry of the extracted species of this metal ion was determined on the basis of the slope analysis method. The reaction proceed by solvation and the probable extracted species found were LaSal-HSal .2Cyanex-923.

Catalytic nucleophilic fluorination by an imidazolium ionic liquid possessing trialkylphosphine oxide functionality

Abstract The synthesis of a new alkylmethylimidazolium ionic liquid wherein the alkyl group is functionalized with dihexylphosphine oxide moiety at the terminal position has been achieved in four steps from 1-methylimidazole. This hybrid ionic liquid effectively catalyzed the nucleophilic fluorination of primary alkyl mesylates under mild conditions using CsF as the fluoride source with a faster rate compared to butylmethylimidazolium mesylate. The hybrid catalyst was recycled 5 times without compromising the yield and purity of the product. The nucleophilic fluorination has been used for the synthesis of diethyl 2-(5-fluoropentyl)-2-methyl malonate, a precursor of 18F isotopomer of an apoptosis imaging agent and the protected form of O-(2′-fluoroethyl)- l -tyrosine, a 18F isotopomer of a tumor imaging agent.

Phase structure and aqueous stability of TRPO waste incorporation into Gd2Zr2O7 pyrochlore

The present work explores the potential of Gd2Zr2O7 pyrochlore based materials for incorporation of trialkyl phosphine oxides (TRPO) waste which is a mixture of multi-nuclides with multi-valence. A series of (Gd,A)2(Zr,B)2O7 ceramics were synthesized to investigate the influence of multi-nuclides incorporation on phase structure and aqueous stability of Gd2Zr2O7. XRD and BSE results show that all the ceramics exhibit a single pyrochlore structure. Raman spectroscopy reveals that the degree of structural order for (Gd,A)2(Zr,B)2O7 solid solutions increases with enhanced TRPO waste content. In addition, aqueous stability testing was carried out using the MCC-1 static leach test method. The results demonstrate that the normalized release rates of the elements in TRPO waste are kept in a low value below 10−4gm−2d−1. La shows the highest normalized release rate of all the involved elements, while Zr exhibits the best chemical stability.