Di-nonyl Phenyl Phosphoric Acid Research Articles

Uranium(VI) extraction from concentrated Egyptian wet-process phosphoric acid using a synergistic organophosphorous solvent mixture

Uranium(VI) recovery from concentrated Egyptian hemi-dihydrate wet-process phosphoric acid, 9.2 M, is investigated using synergistic organophosphorous solvent mixture of dinonyl phenyl phosphoric acid (DNPPA) and tris(2-ethylhexyl)phosphate (TEP). The effect of various factors such as [DNPPA] concentration, [TEP] concentration, phosphoric acid concentration, shaking time, aqueous: organic phase’s ratio (V aq/V org), stability of the solvent, the diluents effect, and temperature on the degree of extraction has been established. The effect of different stripping agents was investigated. The enthalpy change of the uranium extraction process was determined and the extracted uranium is further subjected to a second cycle of extraction [0.3 M D2EHPA + 0.075 M TOPO], scrubbing impurities (5 M sulfuric acid), and finally stripping with 1 M (NH4)2CO3 solution. Precipitation of uranium in highly pure UO3 product using hydrogen peroxide and heat treatment at 375 °C were carried out.

Extraction of neodymium from nitric acid feed solutions using an emulsion liquid membrane containing TOPO and DNPPA as the carrier extractants

The transport of Nd(III) from nitric acid medium across emulsion liquid membrane (ELM) using di-nonyl phenyl phosphoric acid (DNPPA) as the carrier extractant and Span 80 (sorbitol monoleate) as the surfactant in Petrofin as the diluent and sulphuric acid as the internal phase has been systematically investigated. The effect of different physical and chemical parameters such as stirring speed, neodymium concentration, external phase nitric acid concentration, extractant concentration, external to internal phase volume ratio, stripping agent concentration has been investigated on the extraction of Nd(III). The synergistic extraction of the metal ion has also been studied using mixtures of DNPPA and tri-n-octylphenyl phosphine oxide (TOPO) as the carrier extractants in the ELM. Quantitative extraction (>97%) of Nd(III) was observed with 0.3M DNPPA+0.13M TOPO and 1% (v/v) Span 80 liquid membrane at external to internal phase volume ratio of 10 for a feed having 500mg/L Nd(III) at 0.5M nitric acid concentration. The mechanism of extraction of Nd(III) has also been discussed in the light of the results obtained.

Studies on yttrium permeation through hollow fibre supported liquid membrane from nitrate medium using di-nonyl phenyl phosphoric acid as the carrier phase

The transport behaviour of yttrium from nitrate medium was investigated using dinonyl phenyl phosphoric acid (DNPPA) as a carrier in liquid membrane phase, employing microporous hydrophobic hollow fibre supported liquid membrane (HFSLM) module. The influence of feed composition, carrier concentration, feed acidity, strip acid concentration and flow rate of feed on permeability and flux of Y(III) is discussed. The stripping solution was sulphuric acid solution. Increasing the carrier concentration increased the % transport of yttrium, while an increase in the feed metal concentration decreased the percentage transport. A lower acidity in the feed solution and 3M H2SO4 concentration in the stripping phase are favourable for the transport process due to the increase of mass transfer driving forces. The % transport of yttrium increased with an increase in flow rates up to 100mL/min. Under optimized conditions of 0.2M DNPPA, 1g/L Y(III), 0.05M feed acidity, 3M strip acid (H2SO4) and 100mL/min flow rate, the % transport of yttrium was more than 95% in 5h of operation.

Studies on the Separation and Recovery of Plutonium from Nitric Acid Medium using Di-nonyl Phenyl Phosphoric Acid (DNPPA) / n-Dodecane as Extractant System

This paper deals with the studies on the separation and recovery of plutonium from nitric acid medium using Di-nonyl phenyl phosphoric acid (DNPPA) in n-paraffin as an extractant system. The different extraction parameters were investigated. The percentage extraction of plutonium decreased with increase in nitric acid concentration. The optimum solvent concentration for quantitative separation of plutonium from aqueous feed solution was 0.15 M of DNPPA whereas n-paraffin/n-dodecane was the most suitable of diluents with an organic to aqueous phase ratio of 1:1. Among the various strippants used, 0.5 M solution of (NH4)2CO3 was found to be the most suitable for back extraction of plutonium from the loaded organic phase. The developed method was used to separate and recover plutonium from actual wash solution of ion exchange column used for plutonium purification. More than 73% of plutonium was separated from 7 M HNO3 wash solution using 0.15M of DNPPA in n-dodecane.

New synergistic solvent mixture of DNPPA and bidentate octyl (phenyl) CMPO for enhanced extraction of uranium (VI) from phosphoric acid medium

The synergistic extraction of uranium from phosphoric acid solutions with di-nonyl phenyl phosphoric acid (DNPPA) and bidentate n-octyl (phenyl)-N,N-di-isobutyl carbamoyl methyl phosphine oxide (CMPO) in n-dodecane has been investigated and effect of varying concentrations of phosphoric acid, phosphate ions, DNPPA and CMPO on the extraction of uranium were determined. The results demonstrated that synergistic combination of DNPPA with bidentate CMPO significantly enhances the extraction efficiency when compared to monodentate extractant TOPO (tri-n-octyl phosphine oxide). Stoichiometry of complex obtained by slope analysis method indicated the formation of neutral species of the type [UO2(HA2)2·CMPO], where (HA)2 is the dimer form of DNPPA. Extraction reaction was found to be exothermic with enthalpy change (ΔH) of 43.3kJ/mol. A mole ratio of DNPPA/CMPO=2 was found to be suitable for effective extraction of uranium. Under comparable condition, the extraction of uranium from phosphoric acid with various synergistic reagents followed the order: DNPPA/CMPO>DNPPA/TOPO>DIDPA (di-isodecyl phosphoric acid)/CMPO>DIDPA/TOPO>D2EHPA (di-2-ethyl hexyl phosphoric acid)/CMPO>D2EHPA/TOPO. The loading capacity of DNPPA/CMPO was found to be greater than DNPPA/TOPO for both WPPA (wet process phosphoric acid) and MGA (merchant grade phosphoric acid). Stripping of uranium with various reagents was in the order: Na2CO3>H3PO4+Fe>H3PO3>HCOOH. DNPPA and CMPO solvent mixture was found to be stable even after 20cycles of repeated extraction and stripping operations.

Adsorptive Separation of Entrained Di-Nonyl Phenyl Phosphoric Acid from Merchant Grade Phosphoric Acid by Activated Charcoal: Kinetic and Equilibrium Studies

The separation of entrained di-nonyl phenyl phosphoric acid (DNPPA) from merchant grade phosphoric acid (MGA) by adsorption on the coconut shell based activated charcoal has been carried out. The effect of various process parameters, such as DNPPA concentration in aqueous phase of MGA, equilibrium time, amount of activated charcoal and temperature upon adsorption capacity of activated charcoal has been studied. The results showed that the adsorption equilibrium was reached after 240 minutes. The adsorption phenomenon followed pseudo-second order kinetics. Adsorption of DNPPA increased with initial concentration of DNPPA in the range of 50 to 200 mg/L. The experimental data fitted well with the Freundlich isotherm model. Decrease in adsorption with increase in temperature suggests that the adsorption process is exothermic in nature. The value of enthalpy change (ΔH = −35.52 kJ/mol) indicated that DNPPA adsorption on activated charcoal is a physisorption phenomenon. Column operation was carried out to obtain a breakthrough curve. Desorption of DNPPA with 10% NaOH yielded near quantitative regeneration of activated charcoal in three contacts.

Solvent extraction studies on rare earths from chloride medium with organophosphorous extractant dinonyl phenyl phosphoric acid

Extraction behaviour of rare earths, La, Dy and Y, from hydrochloric acid medium by di-nonyl phenyl phosphoric acid (DNPPA) has been investigated over a wide range of experimental conditions such as feed acidity, feed concentration, DNPPA concentration, diluents, temperature, stripping reagents. The slope analysis method indicated the formation of [RE(HA2)3] type of neutral species in the organic phase. The extraction reaction of rare earths with DNPPA was found to be exothermic with ∆H values being −10.6kJ/mol (La), −12.9kJ/mol (Dy) and −17.5kJ/mol (Y). The ∆S values were found to be −42.5 (La), −37.3 (Dy) and −43.0 (Y) J/mol K. The free energy change (∆G) were found to be −2.2 (La), −1.6 (Dy) and −4.5 (Y) KJ/mol at 303K. Stripping of rare earth was >90% from rare earth loaded DNPPA by sulphuric acid (7M) in a single contact at room temperature (303K). Extraction of rare earths in different diluents followed the order: petrofin~dodecane>dichlorobenzene>xylene>chlorobenzene. The extraction efficiency for rare earths by DNPPA increased with increase in atomic number: La<Ce<Pr<Nd<Sm<Eu<Gd<Tb<Dy<HoY<Er<Tm<Lu. Separation factors between these metal ions were calculated and compared with extractants such as di-2-ethylhexyl phosphoric acid (D2EHPA) and 2-ethylhexyl 2-ethylhexyl phosphonic acid (EHEHPA). DNPPA was found to be stable even after 10cycles of repeated extraction/stripping operations.

An Insight into the Speciation and Extraction Behavior of Eu(III) with Dinonyl Phenyl Phosphoric Acid and Di(2-ethylhexyl) Phosphoric Acid: Solvent Extraction and Fluorescence Studies

The speciation of Eu(III) with dinonyl phenyl phosphoric acid (DNPPA) and di(2-ethylhexyl) phosphoric acid (D2EHPA) extracted from nitric acid medium were investigated using time resolved fluorescence spectroscopy (TRFS) technique. The fluorescence life time measurements on both the systems indicated that the Eu(III)-DNPPA complex contains 2H2O molecules in the inner coordination sphere while Eu(III)-D2EHPA complex does not contain any H2O molecule. These studies indicated the formation of Eu(HA2)3 · 2H2O species in the organic phase using DNPPA and Eu(HA2)3 using D2EHPA as extractants (HA: DNPPA/D2EHPA). No change in fluorescence lifetimes and spectra with increased nitric acid and extractant concentration indicated the presence of identical species. However, the presence of neutral donors such as tri-n-butyl phosphate (TBP), Cyanex 923 (a mixture of four trialkyl phosphine oxides viz. R3PO, R2R′PO, RR′2PO and R′3PO where R: n-octyl and R′: n-hexyl chain) showed spectral changes for both the extractants. There was an increase in fluorescence life time from ∼400 µs to ∼1500 μs for Eu(III)-DNPPA system in the presence of neutral donors indicating complete dehydration of the extracted species. By contrast, no change in fluorescence life time was observed in the case of Eu(III)-D2EHPA system after the addition of neutral donors.

Studies on Phase Separation Kinetics in Solvent Extraction for Uranium Recovery in DNPPA + TOPO/MGA System

The present paper deals with the study on phase separation kinetics of di nonyl phenyl phosphoric acid (DNPPA)–tri octyl phosphine oxide (TOPO)–petrofin–phosphoric acid system. Factorial design of experiment (DOE) has been utilized to illustrate the effect of different process variables such as extractant concentration in the organic phase, phosphoric acid concentration in the aqueous phase, temperature, phase ratio, and stirring speed on phase separation time (tp) and specific settling rates (SSR of organic and aqueous phase). The dependence of individual variables and their mutual interactions on phase separation kinetics was also deduced. A mathematical correlation relating process variables and response (tp and SSR) was developed which allows defining the percent effect of each of the variables on response. The influence of variables on response was found to be significant at 99% confidence level, while the interaction effect among variables aqueous acid concentration, organic concentration, and temperature on tp was significant at 95% confidence level. Dimensionless mathematical correlations were transferred to real variables empirical model to predict the phase separation behavior of DNNPA-TOPO-petrofin-phosphoric acid system and found to be in good agreement with the experimental data.

Aggregation behavior of dinonyl phenyl phosphoric acid (DNPPA): Dynamic Light Scattering and spectrophotometric investigations

Dynamic Light Scattering (DLS) and spectrophotometric studies were carried out to investigate the aggregation behavior of dinonyl phenyl phosphoric acid (DNPPA) under varying experimental conditions such as aqueous phase acidity, nature of diluents, and ligand concentration. The aggregation of 0.05M DNPPA/n-dodecane and the extraction of U(VI) and rare earth elements (REE) decreased with increase in nitric acid concentration. This observation was further supported by changes in absorption spectra of DNPPA pre-equilibrated with increasing concentrations of nitric acid.

Studies on Permeation of Nd (III) through Supported Liquid Membrane Using DNPPA + TOPO as Carrier

The transport behavior of Nd (III) through a supported liquid membrane (SLM) containing PTFE as support with organophosphorus extractant dinonyl phenyl phosphoric acid (DNPPA) carrier has been studied. The effect of neutral donors such as TOPO (tri-n-octyl phosphine oxide) TBP (tri-n-butyl phosphate), TEHP (tris 2-ethylhexyl phosphate) and Cyanex 923 (a mixture of four trialkyl phosphine oxides) in combination with DNPPA on transport of Nd (III) from HCl across SLM has been examined and the following trend was observed: TOPO > Cyanex 923 > TBP > TEHP. The effect of experimental variables such as feed acidity (0.5 to 5 M HCl), neodymium metal ion concentration (6.94 × 10−4 to 6.94 × 10−3 M), DNPPA concentration (0.2 to 0.6 M), stripping reagents in the receiving phase on Nd (III) transport across SLM were investigated. The percentage transport of Nd (III) was 97% after 6 hr run with 0.6 MDNPPA + 0.13 MTOPO as carrier. The permeability of Nd (III) decreased with increase in HCl and Nd (III) concentration in the feed solution. The transport of Nd (III) decreased with increase in membrane thickness as well as with decrease in pore size. Under optimized conditions transport behavior of other rare earths was also investigated independently, the trend observed was: La > Pr ≥ Nd > Sm > Eu > Gd > Tb > Dy > Ho > Er > Tm > Lu ≥ Y.

Non-dispersive solvent extraction of neodymium using a hollow fiber contactor: Mass transfer and modeling studies

Non-dispersive solvent extraction (NDSX) of Nd(III) from nitric acid feed solutions was carried out for the first time employing a hollow fiber contactor which used a mixture of di-nonyl phenyl phosphoric acid (DNPPA) and tri-n-octylphosphine oxide (TOPO) in petrofin as the carrier extractant. The transport efficiency was found to be reasonably good with quantitative metal ion recovery (>99.9%) in about 30min. The effect of feed acidity, extractant concentration, flow rates of feed and extractant solution on the transport of neodymium was investigated in recycling mode. For possible applications to different types of feed solutions, NDSX studies were also carried out at varying Nd concentrations and linear increase in Nd mass transfer was seen resulting in quantitative transport in about 40min for feeds containing as high as 1.6g/L of Nd. Various diffusional parameters for the mass transfer of neodymium in the extractant solution were calculated. A mathematical model was developed for prediction of the extraction behavior of Nd(III) in the extractant solution and mass transfer coefficients were calculated. The developed model was successfully validated with the experimental results under different feed conditions.

Kinetic modeling of uranium permeation across a supported liquid membrane employing dinonyl phenyl phosphoric acid (DNPPA) as the carrier

This paper reports the permeation of U(VI) from nitric acid medium across polytetrafluoroethylene (PTFE) membrane impregnated with dinonyl phenyl phosphoric acid (DNPPA) as carrier. The effects of various parameters such as nature and concentration of receiver phases, feed acidity, carrier/uranium concentration and membrane thickness were evaluated. 6M H2SO4 was identified as receiver phase. Experimental data were fitted to a kinetic model to calculate the diffusion coefficient D(o) and mass transfer coefficients Δ(a)−1. The optimized conditions were applied for recovery of uranium from uranyl nitrate raffinate (UNR) waste solution generated during the purification of uranium through U(VI)–HNO3–TBP route.

Carrier facilitated transport of uranium across supported liquid membrane using dinonyl phenyl phosphoric acid and its mixture with neutral donors

Carrier facilitated transport of U(VI) from nitric acid medium across supported liquid membrane (SLM) has been studied under varying experimental conditions, namely feed, carrier, receiver phase compositions, pore size and membrane thickness etc. Microporous polytetrafluoroethylene (PTFE) membranes were used as a solid support and dinonyl phenyl phosphoric acid (DNPPA) either alone or in combination with neutral donors dissolved in n-paraffin was used as carrier. Receiver phases like H2SO4, Oxalic acid, Citric acid and Na2CO3 were evaluated. 2M H2SO4 appeared to be most effective as receiver for U(VI) transport across SLM under the conditions of these studies. The permeability coefficient (P) evaluated for 0.1M DNPPA in combination with 0.05M neutral donors showed the U(VI) transport order: Cyanex 923~TOPO>TBP>TEHP. The permeability (P) of U(VI) decreased with increase in HNO3 concentration and with metal ion concentration in feed solution. The variation of Cyanex 923 concentration at fixed DNPPA concentration (0.1M) revealed that U(VI) permeation across SLM was maximum at 1:2.5 mole ratio. The synergistic mixture of 0.1M DNPPA+0.05M Cyanex 923 was used for uranium recovery from uranyl nitrate raffinate (UNR) solution.

Studies on di-nonyl phenyl phosphoric acid (DNPPA): a potential extractant for uranium recovery from merchant grade phosphoric acid (MGA)

ABSTRACT Methods of purification of di-nonyl phenyl phosphoric acid (DNPPA), its solubility in different aqueous solutions and its recovery from acidic as well as alkaline solutions employing various diluents have been described. Liquid-solid separation method based on Nd-DNPPA salt precipitation route as well as by liquid-liquid separation based on mono ethylene glycol treatment has been studied for the purification of DNPPA. While the purity obtained in the two methods was >94%, the recovery in Nd-DNPPA salt method was only 50% as compared to 90% in mono ethylene glycol method. The solubility of DNPPA in aqueous streams like WPA (5.6 M), MGA (12 M), sulphuric acid (5.4 M), phosphoric acid (5.5 M), oxalic acid (0.95 M), sodium carbonate (1.13 M), water etc. has been determined. Recovery of DNPPA from aqueous phase was investigated employing various diluents such as petrofin, benzene, toluene, MIBK, iso-decanol, 1-octanol, etc. The effects of process variables such as phase ratio (O/A), pH, DNPPA concentr...

Studies on di-nonyl phenyl phosphoric acid (DNPPA): A potential extractant for uranium recovery from merchant grade phosphoric acid (MGA)

Studies on di-nonyl phenyl phosphoric acid (DNPPA): A potential extractant for uranium recovery from merchant grade phosphoric acid (MGA)

Evaluation of dinonyl phenyl phosphoric acid (DNPPA) and its synergistic mixtures with neutral oxodonors for extraction and recovery of uranium from nitric acid medium

The extraction behavior of uranium (VI) from nitric acid medium was investigated using dinonyl phenyl phosphoric acid (DNPPA: monomeric form (HA), dimeric form (H2A2)) as extractant either alone or in combination with neutral oxodonors (S) such as tri-n-butyl phosphate (TBP), tris(2-ethylhexyl) phosphate (TEHP), and Cyanex 923 (a mixture of four different trialkyl phosphine oxides) dissolved in n-paraffin. Indigenously synthesized DNPPA was purified by two routes namely (a) liquid–solid separation using neodymium salt, and (b) liquid–liquid separation using mono ethylene glycol. An attempt was made to compare different phosphoric acid extractants viz. di(2-ethylhexyl) phosphoric acid (D2EHPA), 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A), bis(2,4,4-trimethyl pentyl) phosphinic acid (Cyanex 272) vis-à-vis DNPPA, for the extraction of uranium from nitric acid medium. The effects of different experimental parameters such as aqueous phase acidity (up to 8M HNO3), extractant and metal ion concentration etc. on uranium extraction were investigated. The presence of neutral oxodonors like TBP, TEHP, Cyanex 923 along with DNPPA showed synergistic enhancement in the extraction of U(VI) in the order: Cyanex 923>TBP>TEHP. The stoichiometry of the extracted U(VI) species using synergistic mixtures conformed to UO2(HA2)2·2S. These studies suggest that binary mixtures of DNPPA and neutral donors can be applied for uranium recovery from nitric acid media.

Uranium Permeation from Nitrate Medium Across Supported Liquid Membrane Containing Acidic Organophosphorous Extractants and their Mixtures with Neutral Oxodonors

Permeation of U(VI) from nitric acid solution has been studied across supported liquid membrane (SLM) using bis[2,4,4 trimethyl pentyl] phosphinic acid (Cyanex 272) either alone or in combination with neutral donors like Cyanex 923 (a mixture of four trialkyl phosphine oxides viz. R3PO, R2R′PO, RR′2PO, and R′3PO where R: n-octyl and R′: n-hexyl chain), TBP (tri-n-butyl phosphate), and TEHP (tris-2-ethylhexyl phosphate) dissolved in n-paraffin as carriers. Effect of various other parameters such as nature and concentration of receiver phase, feed acidity, uranium concentration, pore size, and membrane thickness on U(VI) transport across SLM were investigated. Transport behavior of U(VI) was also compared with other derivatives of phosphoric acids like 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A), dinonyl phenyl phosphoric acid (DNPPA) under identical conditions and it followed the order: Cyanex 272 > PC88A > DNPPA. 2 M H2SO4 was suitable for effective U(VI) transport across SLM. Presence of neutral donors in carrier showed significant enhancement in U(VI) permeation in the order: Cyanex 923 > TBP > TEHP. U(VI) transport decreased with increased membrane thickness as well as decrease in pore size. The optimized conditions were tested for recovery of U(VI) from uranyl nitrate raffinate (UNR) waste generated during purification of uranium.

06/01631 Separation of uranium from weak phosphoric acid using di-nonyl phenyl phosphoric acid in combination with tri-n-butyl phosphoric acid: Vijayalakshmi, R. et al. International Journal of Nuclear Energy Science and Technology, 2005, 1, (2–3), 178–183

06/01631 Separation of uranium from weak phosphoric acid using di-nonyl phenyl phosphoric acid in combination with tri-n-butyl phosphoric acid: Vijayalakshmi, R. et al. International Journal of Nuclear Energy Science and Technology, 2005, 1, (2–3), 178–183

Separation of uranium from weak phosphoric acid using di-nonyl phenyl phosphoric acid in combination with tri-n-butyl phosphoric acid

A process has been described for the extraction of uranium from weak phosphoric acid using di-nonyl phenyl phosphoric acid in combination with synergistic reagent tri-n-butyl phosphate. The effect of process parameters including concentrations of extractant and phosphoric acid has been studied. A plausible extraction mechanism has been established using slope analysis technique. The enthalpy change for extraction process, ΔH, was determined for the solvent with and without synergistic reagent. Based on the optimised parameters batch counter current extraction and stripping have been studied and the uranium recovery was found to be ∼80%.