Mixture Of Di(2-ethylhexyl) Phosphoric Acid Research Articles

Study of plutonium recovery from acidic feed using polyethersulfone encapsulating TBP, DEHPA, and mixture of TBP and DEHPA beads

ABSTRACT Polyethersulfone (PES) composite beads encapsulating the extractants di-(2-ethylhexyl) phosphoric acid (DEHPA), tributyl phosphoric acid (TBP), and mixture of DEHPA & TBP were synthesized. The synthesis was carried out using phase inversion method. Subsequently, these PES beads were applied for the recovery of plutonium [Pu (IV)] from different aqueous acidic medium. In kinetic studies, the extraction of Pu (IV) was found to be fast and equilibrium was attained within 5 minutes. In batch sorption studies, the role of aqueous acidity and nitrate ion concentration on extraction efficiency was evaluated. Also, the effects of variation of acid medium, concentration of metal ion, extractant concentration were examined for Pu (IV) recovery. Back extraction was effectively carried out using oxalic acid. The reusability of the PES beads was tested for 10 extraction – stripping cycles.

Enhancing the Vanadium Extraction Performance Using Synergistic Mixtures of D2EHPA and TBP in RDC Column with the Perforated Structure; Case Study: Evaluation Probability Density Functions

The reactive extraction behavior on the mean drop size and distribution for synergistic extraction of vanadium from sulfate medium with di-(2-ethylhexyl) phosphoric acid (D2EHPA) and its mixture with tributyl phosphate (TBP) in kerosene has been interpreted in the modified rotating disc contactor column. In batch experiments, the maximum extraction efficiency was obtained in the single extraction system with 0.29 molar D2EHPA at an equilibrium pH of 2, whereas the extraction percentage was significantly increased by adding 0.3 molar TBP into the same D2EHPA concentration due to the synergistic effect. The solvent extraction process has been optimized by applying the central composition design approach in the column experiments. The influence of operational variables such as agitation rate and both phase flow rates as well as the type of used systems have been investigated on drop behavior. A unified model was provided for modified rotating disc columns. It was found from Monte Carlo simulation for uncertainty analysis that the agitation speed and type of utilized systems, namely reactive or physical systems have more profound impacts on the mean drop size. The optimum conditions were obtained at the agitation rate of 400 rpm, and phase flow rates equal to 26 L/h.

Extraction and separation of La(III), Pr(III) and Nd(III) using binary mixture of D2EHPA with Cyanex272, TOPO, and TBP extractants

This paper investigated the extraction and separation of lanthanum(III), praseodymium(III) and neodymium(III) from aqueous hydrochloric acid solutions using a mixture of di-(2-ethylhexyl) phosphoric acid (D2EHPA) with three other extractants, namely bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272), trioctylphosphine oxide (TOPO) and tri butyl phosphate (TBP) diluted in kerosene. In this study, the O/A = 1, T = 25 °C (room temperature), contact time of 10 minutes for the two phases, and kerosene as the diluent were chosen for all experiments. The effective factors studied in this research included the type and concentration of extractants as well as the pH of solutions. The Design Expert software was employed for the design of experiments, investigating the factors effect on the solvent extraction and the separation factor (β), and obtaining the optimal values of the factors. After a thorough analysis of the experiments, it was concluded that these factors were independent and had no interaction on each other. The maximum extraction and separation of Pr(III) and Nd(III) were attained by the mixture of D2EHPA and Cyanex272 in which the ratio of D2EHPA to Cyanex272 equaled 0.5 at pH = 4.4. Their extraction values were 90.5%, 91.3% respectively and β(Nd+Pr)/La = 14.4. In this condition, the extraction of La(III) was 50.81%. Based on this data, a two-stage extraction was used for the separation of Nd and Pr from the La, with an extraction efficiency of 97.5%, 96.9%, and 28.3% for Nd, Pr, and La, respectively. In order to selectively remove the co-extracted La from the loaded organic phase (D2EHPA + Cyanex272), the scrubbing of La was carried out with a new immiscible aqueous solution of Nd with the concentration of 251 mg/L as the scrubbing solution with a scrubbing efficiency of 85%.

Solid phase extraction of uranium from phosphoric acid: kinetic and thermodynamic study

Abstract There is a high interest to develop suitable solid phase extractants for uranium separation from aqueous solutions in order to reduce cost and enhance the efficiency. This paper describes solid phase extraction of uranium(VI) from aqueous phosphoric acid solution using MCM-41 based D2HEPA-TOPO organophosphorous extractants. The mixture of D2HEPA (di-2-ethyl-hexylphosphoric acid) and TOPO (tri-n-octylphosphine oxide) was impregnated into the pores of MCM-41 and the synthesized sorbent was fully characterized. The influences of different factors such as synergistic mixture ratio, phosphoric acid concentration, mixing time and temperature were investigated. The results showed that 90% of uranium(VI) extraction can be achieved within 5 min, using D2HEPA-TOPO@MCM-41 (mass ratio 2:1 w/w) from 1 M phosphoric acid containing 64 ppm of uranium at room temperature. High adsorption capacity of uranium(VI) have been achieved at the mentioned conditions. The rate constant for the chemical adsorption of uranium(VI) was 0.988 g mg‒1 min‒1 calculated by the pseudo-second order rate equation. The obtained thermodynamics parameters showed that uranium(VI) adsorption from H3PO4 is an exothermic and spontaneous process.

Investigation on molecular interaction studies of binary mixture of DEHPA and petrofin at 298.15 K

ABSTRACTThe present article reports the values of density (ρ12), molar volume (V12), apparent molar volume (Vɸ), dielectric constant (ϵ12), molar polarisation (P12) and molar refraction (R12) of binary mixture of di-2-ethylhexyl phosphoric acid (DEHPA) and petrofin at various compositions. The excess properties such as VE, ϵE, ΔnD, PE and RE have been calculated to throw light on the existence of interaction between the DEHPA and petrofin molecules in the binary mixture. The values of VE and RE were found to be positive while the values of ϵE, ΔnD and PE were negative over the entire composition showing weak interaction between the two unlike molecules in the mixture. The Kirkwood-correlation factors (g) have been evaluated to know the nature of interaction prevailing in DEHPA and petrofin. These data provide useful information regarding interaction between self-associated protic DEHPA and non-associated petrofin which in turn helps the metallurgist to use DEHPA diluted with petrofin as effective solvent in extraction of metals.

Synergistic extraction of amoxicillin from aqueous solution by using binary mixtures of Aliquat 336, D2EHPA and TBP

Abstract Amoxicillin extraction was conducted using the single organic extractant namely trialkylmethylammonium chloride (Aliquat 336), di-(2-ethylhexyl)-phosphoric acid (D2EHPA) and tributylphosphate (TBP) and followed by the synergistic extraction using the binary mixtures of the mentioned extractants. Maintaining an initial pH of amoxicillin aqueous solution at 10 yielded the highest extraction percentage for all extractants. Increasing extractant concentrations from 2 to 12 mM produced the positive effect on amoxicillin separation for all extractants except for TBP with the highest extraction percentage and distribution coefficient reported at 86.2 ± 1.10% and 6.25 ± 0.267, respectively when maintaining Aliquat 336 at 12 mM. Synergistic extraction was observed when the mixtures of D2EHPA and TBP as well as Aliquat 336 and TBP were employed with the maximum extraction percentage and distribution coefficient reported at 90.4 ± 0.39% and 9.44 ± 0.459, respectively when maintaining the molar ratio of Aliquat 336 to TBP at 10:2.

Study on the synergistic extraction of vanadium by mixtures of acidic organophosphorus extractants and primary amine N1923

Abstract In the present study, the solvent extraction of vanadium from chloride medium with acidic organophosphorus extractants, primary amine N1923, and their mixtures were investigated. The organophosphorus acids included di(2-ethylhexyl) phosphoric acid (D2EHPA), 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester (HEHEHP), and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272). The extraction effects from chloride medium were studied in detail, illustrating that all the three mixtures of organophosphorus acids and N1923 have synergistic effects on vanadium. As a representative, extraction stoichiometries of vanadium with D2EHPA + N1923 were studied with the methods of slope and constant mole. The extraction capacity of temperature dependency was also investigated. Moreover, the separation of vanadium, nickel, and chromium with mixtures of D2EHPA + N1923 was studied.

Separation of ND(III), DY(III) and Y(III) by solvent extraction using D2EHPA and EHEHPA

The equilibrium separation of trivalent rare earth elements (Nd(III), Dy(III), and Y(III)) from hydrochloric acid solution by di-(2-ethylhexyl) phosphoric acid (D2EHPA) and 2-ethylhexylphosphonic acid mono-2-ethyl hexyl ester (EHEHPA) separately and in mixtures has been studied. The effect of extractant concentration, extractant mixture composition and solution acidity has been investigated. The results show that a mixture of D2EHPA and EHEHPA provide a better separation of Y(III) from Dy(III) when the total extractant concentration is 0.06 and 0.09mol/L, while the separation is better using pure EHEHPA at higher extractant concentration (0.15mol/L). The separation of Nd(III) from Y(III) and Dy(III) is higher using pure D2EHPA (0.06 and 0.15mol/L). The results show that for the complexation of the Nd(III) ions approx. 1–2 hydrogen ions/rare earth element (REE) ion are released to the aqueous phase upon binding approximately 1 extractant dimer on average. For the complexation of Y(III) and Dy(III) ions 2–3 hydrogen ions are released upon binding approximately two extractant dimers on average. Accordingly, under the conditions of this work the complexation involves not only extractant molecule dimers but also monomers or aggregated REE species to some extent, and a fraction of the REE is extracted as chloride complexes.

Synergistic extraction and separation of Dysprosium and Europium by supported liquid membrane

Synergistic extraction and separation of Dysprosium (Dy) and Europium (Eu) via supported liquid membrane (SLM) were investigated using mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and Bis (2,4,4-trimethylpentyl) phosphinic acid (Cyanex272). The results showed that separation of Dy and Eu was highly dependent on the pH of feed solution. Dy can be extracted more than Eu, because the equilibrium constant for Dy using the mixture of D2EHPA and Cyanex272 was greater than that for Eu. Various parameters were optimized to achieve maximum separation factor, namely feed phase pH, carrier concentration and stripping phase concentration. The membrane was stable at six cycles of operation.

Study on the removal of chromium(III) by solvent extraction

abstract The extraction of chromium(Ш) from aqueous waste solution by extractants 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (HEHPEHE), di(2-ethylhexyl) phosphoric acid (D2EHPA), and mixture of D2EHPA with other extractants is carried out, respectively. It is found that the extractant HEHPEHE exhibited high extraction selectivity for chromium(III) from aqueous waste solution. Based on the molecular structure of HEHPEHE, it is confirmed that the extraction mechanism of chromium(III) by HEHPEHE is mainly determined by cation exchange and chelation. Furthermore, the influences of major factors, such as the initial pH, the initial concentration of extractant, phase ratio, and the extraction temperature on the extraction efficiency of chromium(III) are also investigated and the appropriate process conditions are obtained. At the appropriate conditions, the extraction efficiency of chromium(III) above 99% can be achieved and the treated aqueous waste solution can be discharged directly without polluting the environment.

Metal extraction of a spiked solid with supercritical carbon dioxide

A mixture of D2EPHA (Di-2-Ethyl Hexyl Phosphoric Acid) and n-hexane is used as the extractant solution to extract cobalt ions from a fireproof board in the environment of supercritical carbon dioxide. It is found that the cobalt on the spiked sample can be totally removed in a pilot unit. The influence of the carbon dioxide flow rate, the flow rate of the extractant solution, the ratio of D2EHPA to hexane in the extractant solution, the temperature and the replacement of hexane by methanol are investigated in this study. Upon extraction, the cobalt complex with D2EHPA is precipitated with the extractant solution in a separation tank through depressurization, and the amount of extracted cobalt in the separation tank is sampled and analyzed by ICP-OES. The accumulation of the removed cobalt along the extraction time is plotted as an extraction curve, and a kinetic model is established to predict the extraction. It is found that the kinetic model reasonably fits the experimental data. From the model, it is concluded that the metal extraction depends on reactivity, that the extent of the extraction is determined by the reversible reaction of the ion-exchange between D2EHPA and the cobalt ions and that the adsorption kinetics of the extractant in the environment of supercritical carbon dioxide may play an important role in the initial stage of extraction. The proposed model, which successfully provides an easy and accurate prediction for metal extraction from a porous solid matrix, can help to reveal the extraction mechanism and optimize the operational conditions for future scale-up designs.

Extraction and permeation of cadmium ions through supported liquid membrane impregnated with mixtures of D2EHPA and M2EHPA

The use of an organic carrier consisting of di-(2-ethylhexyl) phosphoric acid (D2EHPA) and mono-(2-ethylhexyl) phosphoric acid (M2EHPA), diluted in kerosene, for separation of cadmium through a supported liquid membrane (SLM) was investigated. The extraction percentage of cadmium and permeability coefficients rose by increasing M2EHPA and feed phase concentration. By increasing the volume percentage of M2EHPA, the permeability coefficient of cadmium increased to a maximum value of 8 cm s−1 at 1·5 vol.-% declining at higher volume percentages. The permeability of cadmium ions through the SLM decreased with time. The permeation coefficient increased as the initial cadmium concentration increased.On a étudié l’utilisation d’un support organique consistant d’acide phosphorique di-(2-éthylhexyle) (D2EHPA) et mono-(2-éthylhexyle) (M2EHPA), dilué dans du kérosène, pour la séparation du cadmium à travers une membrane liquide supportée (SLM). Le pourcentage d’extraction du cadmium et les coefficients de perméabilité s’élevaient avec l’augmentation du M2EHPA et de la concentration de la phase d’alimentation. En augmentant le % de volume de M2EHPA, le coefficient de perméabilité du cadmium augmentait à une valeur maximale de 8 cm s−1 à un volume de 1·5% et déclinait à des % plus élevés du volume. La perméabilité des ions de cadmium à travers la SLM diminuait avec le temps. Le coefficient de perméation augmentait avec l’augmentation de la concentration initiale de cadmium.

Extraction of rare earths using mixtures of sec-octylphenoxy acetic acid and organophosphorus acids

The extraction of rare earths from nitrate medium using three organophosphorus acids, 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEHEHP), di-(2-ethylhexyl) phosphoric acid (D2EHPA), bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272), and their mixtures with sec-octylphenoxy acetic acid (CA12) has been studied in detail. The mixtures have different extraction effects on various rare earths. Synergistic extraction effects are only found when light rare earths and yttrium (III) are extracted with mixtures of D2EHPA and CA12. The possibilities of separating the rare earths with these mixtures are investigated according to the extractabilities. It is feasible and advantageous to separate yttrium (III) from the lanthanoids (III) with HEHEHP + CA12 and D2EHPA+CA12 mixtures at proper extractant ratios. The separation of yttrium (III) from heavy rare earths is also possible with mixtures of Cyanex272 and CA12.

NONDISPERSIVE LIQUID-LIQUID EXTRACTION OF COPPER AND ZINC FROM AN AQUEOUS SOLUTION BY DEHPA AND LIX 984 IN A HOLLOW FIBER MEMBRANE MODULE

ABSTRACT A liquid-liquid extraction procedure was used to study the amounts of Zn2+ and Cu2+ that could be simultaneously extracted from aqueous solution with di(2-ethylhexyl) phosphoric acid (DEHPA) and LIX 984 diluted with n-heptane at equilibrium. LIX 984 is a 1:1 volume blend of LIX 860 (5-dodoecylsalicylaldoxime) and LIX 84 (2-hydroxy-5-nonylacetophenone oxime). At equilibrium, a 0.3 mol/L DEHPA-20% (v/v) LIX 984 solution extracted 99% of both the zinc and copper from a solution that had 100 ppm of each metal. A polysulfone hollow-fiber membrane module with 1 mm ID and 5,000-molecular weight cutoff was used to study the amounts of Zn2+ and Cu2+ that could be simultaneously extracted with a mixture of DEHPA and LIX 984. The aqueous and organic streams were operated at 100% recycle. With a 0.6 mol/L DEHPA-10% (v/v) LIX 984 solution, a 90.5 ± 1.7% (s.d.) extraction of zinc and a 93.70 ± 0.79% (s.d.) extraction of copper was obtained after 180 min.

NONDISPERSIVE LIQUID-LIQUID EXTRACTION OF COPPER AND ZINC FROM AN AQUEOUS SOLUTION BY DEHPA AND LIX 984 IN A HOLLOW FIBER MEMBRANE MODULE

ABSTRACT A liquid-liquid extraction procedure was used to study the amounts of Zn2+ and Cu2+ that could be simultaneously extracted from aqueous solution with di(2-ethylhexyl) phosphoric acid (DEHPA) and LIX 984 diluted with n-heptane at equilibrium. LIX 984 is a 1:1 volume blend of LIX 860 (5-dodoecylsalicylaldoxime) and LIX 84 (2-hydroxy-5-nonylacetophenone oxime). At equilibrium, a 0.3 mol/L DEHPA-20% (v/v) LIX 984 solution extracted 99% of both the zinc and copper from a solution that had 100 ppm of each metal. A polysulfone hollow-fiber membrane module with 1 mm ID and 5,000-molecular weight cutoff was used to study the amounts of Zn2+ and Cu2+ that could be simultaneously extracted with a mixture of DEHPA and LIX 984. The aqueous and organic streams were operated at 100% recycle. With a 0.6 mol/L DEHPA-10% (v/v) LIX 984 solution, a 90.5 ± 1.7% (s.d.) extraction of zinc and a 93.70 ± 0.79% (s.d.) extraction of copper was obtained after 180 min.

Solid-liquid extraction studies of divalent metals with impregnated resins containing mixtures of organophosphorus extractants

The extraction of Zn(II), Cu(II) and Cd(II) from nitrate solutions by impregnated resins containing mixtures of di(2-ethylhexyl)phosphoric acid (DEHPA) and tri- n-octyl-phosphine oxide (TOPO) have been studied. Impregnated resins containing TOPO and mixtures of DEHPA and TOPO have been prepared by direct adsorption of both extractants into macroporous supports, Amberlite XAD2. The adsorption of DEHPA and TOPO molecules on the macroporous support is shown by FTIR spectroscopy to be result of only weak extractant-support interactions. The distribution coefficients of Zn(II), Cu(II) and Cd(II) were determined as a function of pH and extractant concentration (DEHPA, TOPO) in the resin phase and the data were analyzed graphically using the slope analysis method in terms of synergistic effect. Analysis of the results showed that the extraction of these metal ions can be explained assuming the formation of metal complexes in the resin phase with a general composition ML p (NO 3) t S s (HL) q where p, t, s, q take values depending on the metal and the extractant concentration ratio in the resin phase ( [ HL] r [ S] r ).