Comparative studies on co-extraction of uranium(VI) and different mineral acid from aqueous feed solutions using TBP, TOPO and TOA

Das, Diptendu; Juvekar, Vinay A.; Roy, Somnath; Bhattacharya, R.

doi:10.1007/s10967-014-2932-5

Cited by 14 publications

(4 citation statements)

References 16 publications

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“…The choice of these parameters was based on the results of our pervious studies [17]. Also, the following parameters were fixed a priori as optimal (again based on the previous studies [14,17]) and were not subjected to optimization. The composition of the internal strip phase which was 0.5MNa 2 CO 3 for the LEM extraction involving TOPO or TOA, or 2 M H 2 SO 4 for the LEM extraction involving D2EHPA and speed of pertraction.…”

Section: Chemicalsmentioning

confidence: 99%

“…Literature is available on impact of various parameters like ligand concentration, acid concentration in feed phase, viscosity of membrane, etc. on LEM extraction of U(VI) by TOPO [5][6][7][8][9][10][11][12][13][14][15][16]. Also literature is available on extraction of U(VI) by the ligands ( D2EHPA, TOPO and TOA ) using bulk liquid membrane (BLM), SLM and liquid-liquid extraction [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

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Efficacy of extraction of U(VI) by liquid emulsion membrane (LEM) using TOPO, D2EHPA and TOA

Das

Juvekar

Bhattacharya

2015

J Radioanal Nucl Chem

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The response surface methodology is used to obtain optimal rate and extent of extraction of low concentration U(VI) (B100 mg/L) by liquid emulsion membrane technique. Three different ligands viz. Tri-n-octyl phosphine oxide (TOPO), Tri-n-octyl amine (TOA) and Di-(2-ethylhexyl)phosphoric acid (D2EHPA), are used. 2 3 factorial design is applied to generate second order regression equation for studying the effect of concentration of ligand, surfactant and feed acidity. The regression model is in good agreement with the experimental data for all ligands. The rate of extraction of U(VI) by LEM is found to be in the order TOA [ TOPO [ D2EHPA.

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Section: Chemicalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficacy of extraction of U(VI) by liquid emulsion membrane (LEM) using TOPO, D2EHPA and TOA

Das

Juvekar

Bhattacharya

2015

J Radioanal Nucl Chem

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“…It enables amines to contribute in a large variety of reactions as a base or a nucleophile. Amines play a prominent role in the field of extractive metallurgy (Biswas et al, 2017;Das et al, 2014;Gai et al, 2018;Hesford and McKay, 1960). The lone pair of an electron on the nitrogen atom determines the chemistry of aliphatic amines and also by the tendency of the hydrogen atoms bonded to nitrogen to be replaced by other substituents (Biswas et al, 2017;Hesford and McKay, 1960;Saw et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Liquid-liquid extraction of mineral acids using Tri-n-octylamine

Karmakar

Biswas

Khatun

2019

Bangladesh J. Sci. Ind. Res.

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The present work reports the extraction behaviors of mineral acids: HClO 4 , HNO 3 , HCl and H 2 SO 4 (commonly found in acidic bleed solutions from the hydrometallurgical route of metal extraction processes) by tri-n-octylamine (TOA) dissolved in distilled colorless kerosene. The systems have been investigated as functions of various experimental parameters, such as time, [acid], [TOA], temperature, extraction stage and the organic to aqueous phase volume ratio (O/A). Strippings was also examined. Equilibration time is less than 60 min. The acid concentration in the organic phase at equilibrium is increased with increasing initial acid concentration in the aqueous phase for all systems. However, the is after %extraction decreased with increasing initial acid concentration in the aqueous phase. The % extraction increased remarkably with increasing [TOA] for all cases. Being the ratio of the [acid] in the organic to aqueous phase at equilibrium equal to extraction ratio, D; the log D vs. log [TOA] plot is almost a curve with slope 1 at lower concentration region and with slope ~2 at higher concentration region. The extraction efficiency of TOA varies in the order: HClO 4 > HNO 3 > HCl > H 2 SO 4 . The acid-base-neutralization (extraction) reactions are exothermic with ΔH value much higher than -57 kJ/mol obtainable for of a strong acid -strong base neutralization. The loading capacity of extractant (g per 100 g TOA) for acids varied in the order: HClO 4 (30.69) > HNO 3 (20.49) > H 2 SO 4 (17.87) > HCl (10.31). On using lower organic to aqueous phase volume ratio (O/A), the organic phase saturated with acid can be obtained on stage-wise extraction. The extracted organic phase, for all systems (excepting H 2 SO 4 -system) under investigation, can be stripped effectively in a single stage by 0.10 g eq/L NaOH solution to the extents of more than 96%. However, for H 2 SO 4 -system, two-stage stripping will be found effective.

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“…It has been observed that co-extraction of other species, such as water and nitric acid, greatly influences the extraction efficiency, as the presence of water or acid droplets in the organic phase intensifies the coordination mechanism of TBP. 6 Also, the concentration of TBP plays an important role. 7 The transfer of uranyl ions from the aqueous phase to the organic solvent involves many molecular-level events that are not well understood from experiments alone, and hence the description of the extraction mechanism includes a theoretical modeling of the extraction process.…”

Section: Introductionmentioning

confidence: 99%

Passage of TBP–uranyl complexes from aqueous–organic interface to the organic phase: insights from molecular dynamics simulation

Sahu

Ali

Shenoy

2016

Phys. Chem. Chem. Phys.

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The present study reports molecular dynamics simulations for biphasic systems comprising tributyl phosphate (TBP) in dodecane and uranyl nitrate in the aqueous phase, which are key chemical species in the well-known Pu-U extraction (PUREX) process. An attempt has been made to understand the nature of interface and mechanism of 'TBP associated uranyl' crossing under neutral and acidic conditions. Results show that the solvent density undergoes large fluctuation near the interface depending on the nature of the aqueous-organic phase. The study provides compelling evidence of experimentally observed reorganization of interfacial complexes at the interface and their structural reformation during extraction. It has been observed that the surface active nature of TBP and their interfacial coverage is modulated by the nature of incorporated solute species and their location with respect to the interface. Also, the TBP structuring near the interface is destroyed when an acidic interface is considered rather than a neutral one which favors the uranyl extraction. With an acidic interface, the water humidity of organic phase was observed to be increased in the experiments. Furthermore, the acid/water solubility in the organic phase was observed to be influenced by selection of acid models and their concentration. Simulations with high acid concentration show water pocket formation in the organic phase. However, in the case of dissociated ions or a mixture of both, no such water pool is observed and the extracted water remains dispersed in the organic phase, having the tendency to be replaced by HNO3 because of preferred TBP·HNO3 complexation over TBP·H2O. Most remarkably, the present study makes evident the TBP-induced charge redistribution of uranyl complexes during migration from the interface to the bulk organic phase, which contributes to drive uranyl complexes such as UO2·NO3·4TBP, UO2·5TBP and UO2·NO3·3TBP·HNO3 in the organic phase, and this was reestablished by DFT calculations. Thus, the present study inspires future simulation and experimental investigations on the extraction of species at the liquid-liquid interface.

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Comparative studies on co-extraction of uranium(VI) and different mineral acid from aqueous feed solutions using TBP, TOPO and TOA

Cited by 14 publications

References 16 publications

Efficacy of extraction of U(VI) by liquid emulsion membrane (LEM) using TOPO, D2EHPA and TOA

Efficacy of extraction of U(VI) by liquid emulsion membrane (LEM) using TOPO, D2EHPA and TOA

Liquid-liquid extraction of mineral acids using Tri-n-octylamine

Passage of TBP–uranyl complexes from aqueous–organic interface to the organic phase: insights from molecular dynamics simulation

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