TBP In Kerosene Research Articles

Preparation of industrial ammonium diuranate from a boltwoodite ore as a mediator for nuclear fuel and catalytic utilizations

To date, uranium is one of the most crucial critical metals and a high supply-demand gap is forecasted in the coming years. However, the upsurging interest in uranium in nuclear fuel cycles prompted an engineered hydrometallurgical route capable of producing a high-grade ammonium diuranate [(NH4)2U2O7] capable of serving as an intermediate in nuclear base fuel and catalytic industries. Consequently, the processing of an indigenous boltwoodite ore containing admixtures of albite (Na2.00Al2.00Si6.00O16.00), boltwoodite (Na2.00K2.77U3.00Si6.00O9.00H4.00), thorite (Th4.00Si4.00O16.00), and quartz (Si6.00O6.00) by the hydrometallurgical process was examined in hydrochloric acid media. The experimental parameters during leaching including lixiviant concentration, reaction temperature, and particle size on the ore dissolution were investigated. At established conditions (2.5 mol/L HCl, 75 °C, 75 μm), 99.1% of the initial 10 g/L ore was dissolved within 120 min. The estimated activation energy of 17.30 kJ/mol indicated a mixed control reaction mechanism as the rate-determining step for the ore dissolution. The thermodynamic and kinetic tests were also examined to explore dissolution feasibility. The apparent change in enthalpy (ΔH = 73.95 kJ/mol) and negative values of Gibb's free energy change affirmed that the U(VI) extraction is endothermic and spontaneous for temperatures between 300 K and 348 K. Almost 99.3% U(VI) in the pregnant solution was quantitatively extracted using TBP in kerosene, and 97% of the total U(VI) was quantitatively precipitated using NH4OH solution. The precipitate was further crystallized to obtain industrial-grade ammonium diuranate comparable with the international standard specification of nuclear purity ASTM C 788–03; recommended to serve as a mediator in the nuclear fuel and catalytic industries.

Rapid separation of High-viscosity phosphorous Acid/Tributyl phosphate extraction system by a stable anticorrosive Super-PA-phobic mesh

Inefficient, slow separation resulting from the high viscosity of phosphoric acid (PA) is a crucial problem that limits the process economy of industrial PA extraction. In this work, a super-PA-phobic stainless-steel mesh (SPPSSM) with excellent anticorrosion properties and stability is prepared and used for rapid separation in various PA/tributyl phosphate (TBP) extraction systems. The separation efficiency in batch operation of a PA-enriched raffinate (PER) and TBP-enriched phase (TEP) mixture formed from pure PA and TBP exceeds 97.59%, and the maximum TEP flux is 19.2593 L·m−2·h−1 at 60 °C. The maximum TEP flux of 886.1571 L·m−2·h−1 is obtained for a 20 wt% TBP kerosene solution and 20 wt% PA aqueous solution. A continuous separation device using the SPPSSM as the core component maintains a recovery rate of more than 95.57% in long-term operation, confirming its performance stability and robustness. The stable selective penetration of the SPPSSM originates from its super-PA-phobicity, which results from its rough surface with low surface energy; the SPPSSM repels PA but allows TBP to pass through. The separation ability of the SPPSSM is determined by the viscosity, density, and surface tension of the two liquid phases after extraction. It can be predicted using an equation based on the filtration mode after correction by a coefficient representing the Reynolds and Weber numbers. This work proposes a material for the rapid separation of PA/TBP in extraction systems and broadens the application field of superwetted materials under harsh conditions.

Experimental Study and Correlation for Mass Transfer Coefficient in the Pilot Plant Multistage Column with the Presence of Molybdenum

In the present work, multistage extraction column performance for reactive separation of molybdenum from the leach aqueous phase by using D2EHPA and TBP in kerosene was investigated by using axial diffusion model. Initially, the values of initial pH and extractant concentration were optimized on the batch experiments. The variation of volumetric overall mass transfer coefficients based on continuous phase at various operating conditions was obtained. By considering the chemical reaction conditions, the experimental data indicate that the volumetric overall mass transfer coefficients increase with an enhancement in rotor speed and continuous and dispersed phase flow rates. According to the sensitivity analysis, the rotor speed and flow rate of dispersed phase have more influence on column performance. Also, the continuous flow rate has little effect on volumetric overall mass transfer coefficients. After the steady-state condition was established, the concentration profile for the extraction of molybdenum along the column was obtained. The experimental data were studied and compared with the previous models. A new model based on dimensionless numbers was derived from the evaluation of overall mass transfer coefficients with consideration of the reactive extraction system.

Exact hydrodynamic description of pilot plant Oldshue-Rushton contactor: a case study with the introduction of selenium and tellurium into reaction system

ABSTRACT In this paper, the hydrodynamic behaviour of the chemical reaction system (selenium, tellurium, and TBP) was interpreted in the Oldshue-Rushton extraction column. The optimum operating parameters for extracting the selenium and tellurium from chloride medium were carried out by using the batch experiments. The feed acidity of 5 molar and solvent phase with 20% (v/v) TBP in kerosene were optimised to examine the hydrodynamic parameters of the mentioned column. The impacts of operating variables such as rotor speed, inlet aqueous phase velocity, and inlet solvent phase velocity on the dispersed phase hold-up, mean drop size, slip velocity, drop size distribution, and extraction rate were evaluated in the column experiments. The experimental drop size distributions in the Oldshue-Rushton column were fitted with the two modified functions containing the normal and log-normal. The stable parameters within the mentioned functions were connected with the operating variables, reactive and physical systems. Among the two distribution functions, the modified log-normal is found to accomplish sufficiently in the fitting of the drop size distribution. The previous models for predicting the dispersed phase hold-up, mean drop size, and slip velocity as a function of operational parameters, column geometry, and physical properties of the mentioned system were compared with the experimental data, which the available models were sensible precision to anticipation the hold-up values, mean drop size, and slip velocity in this extractor. The results of extracting the selenium and tellurium with TBP in the extractor indicated the column feasibility with the proper extraction for tellurium and selenium in the chloride solution.

Separation of Scandium and Thorium in the Processing of Scandium Rough Concentrate Obtained from Circulating Solutions of In-Situ Leaching of Uranium

Studies have been carried out to separate scandium and thorium from nitric acid solutions using two extraction systems 7.5% Cyanex 923 + 7.5% TBP and 40% TBP in kerosene for processing the primary scandium concentrate obtained from the circulating solutions of underground uranium leaching at JSC “Dalur.” Comparison of the values of the separation coefficients showed the fundamental possibility of using both systems for the separation of scandium and thorium. It was recommended to use a 40% solution of TBP in kerosene at the first stage of separation, and a mixture of extractants 7.5% Cyanex 923 + 7.5% TBP in kerosene at the stage of fine purification. For this system, higher scandium losses due to coextraction with thorium were noted. The possibility was demonstrated of increasing the degree of purification from radioactivity by adding 15% trialkylmethylammonium nitrate to the TBP solution.

Extraction of Molybdenum (VI) and Vanadium (V) from Nitrate Solutions Using Coupling of Acid and Solvating Extractants (RESEARCH NOTE)

In this study, solvent extraction method has been utilized for separation of molybdenum and vanadium from nitrate solution by utilizing coupling of acid and solvating extractants (D2EHPA and TBP extractants). The outcomes demonstrated that synergistic solvent extraction improves stability of formatted complexes for transfer to the organic phase. The main parameters such as pH value, concentration of extractants, NH4OH concentration as the stripping agent and contact time were optimized at 0.4, 15% (v/v) D2EHPA, 10% (v/v) TBP, 2 M and 30 min, respectively. The maximum separation factor of 24.84 was obtained with a new synergistic mixture of D2EHPA and TBP diluted with kerosene. According to McCabe-Thiel diagram, more than 99% of the Mo (VI) was obtained in counter current procedure and three stage numbers using 15% (v/v) D2EHPA and its mixture with 10% (v/v) TBP in kerosene, initial aqueous pH value equal to 0.4 and A/O ratio of 4/1 at room temperature for 30 min. In addition, stripping of Mo (VI) reached 98.75% in three counter current stages using 2 M NH4OH as stripping agent and A/O ratio of 1/4 for 30 min.

The recovery of rare earth metals from WEEE leaching solution via liquid-liquid extraction

<p>The recovery of rare earth metals (REMs) from end-of-life products, such as Waste Electrical and Electronic Equipment (WEEE), is drawing great attention as an attractive strategy for promoting the sustainable development. The hydrometallurgical technique of solvent extraction has been reported to be one of the most interesting method to recover REMs. However, when applied to WEEE, this process is challenged by the heterogeneous composition of electronic waste, completely different from other solid matrices, and it still has much rooms of improvements. This study investigated the extraction, stripping and recovery of REMs from a WEEE leaching solution using Versatic 10 as carrier in the organic phase and oxalic acid as stripping agent. A factorial design was carried out to evaluate the simultaneous effects of factors as the feed phase pH and the concentrations of both extractant and organic phase modifier in the extraction process. Cerium, lanthanum and yttrium were extracted at high percentages using 200 mM of Versatic 10, loaded by 100 mM of TBP in kerosene at pH 7. Moreover, 750 mM of oxalic acid successfully stripped and recovered 7.63 and 13.82 mg/kg of lanthanum and yttrium, respectively.</p>

Solvent extraction separation of zirconium and hafnium from nitric acid solutions using mixture of Cyanex-272 and TBP

AbstractA solvent extraction method has been employed to extract and separate zirconium and hafnium from the nitric acid medium using Cyanex-272 and its mixture with TBP in kerosene. The effects of the experimental parameters such as contact time between phases, aging time, nitric acid concentration, Cyanex-272 and TBP concentration on the metals separation, and various stripping agents on the metals back extraction from the loaded organic phase have been investigated. The maximum separation factor of 16 was obtained in the single extraction system with 1% (v/v) Cyanex-272 from 2.5 M HNO3solution. The combination of Cyanex-272 with TBP exhibited a significant synergistic effect for Zr extraction and the antagonistic effect for Hf extraction. The proposed novel synergistic mixture consisting of 0.5% (v/v) Cyanex-272 and 20% (v/v) TBP in kerosene offered the maximum separation factor of 99.7 from 2.5 M HNO3solution. By applying a slope method, the extracted zirconium species were proposed to be ZrO(NO3)2·2Cyanex272·2TBP in the organic phase. Among the investigated stripping agents, 4 M H2SO4solution showed the best efficiency for the stripping of zirconium and hafnium from the loaded mixture of Cyanex-272 and TBP with separation factor of 10.1.

Extraction of Ruthenium using Both Tertiary and Quaternary Amine from Chloride Media

Ruthenium extraction from a solution bearing 0.1 g/l Ru and 0.0358 M HCl was independently carried out with Alamine 336 and Aliquat 336 in kerosene with tri-n-butyl phosphate as the phase modifier. The effect of various parameters such as concentrations of extractant, hydrochloric acid, sodium chloride and TBP on extraction of ruthenium(III) was investigated. Ruthenium extraction increased with increasing extractant concentration up to 25% beyond which it decreased. With Alamine 336, the percentage extraction increased with increasing HCl concentration up to 6 M and then it decreased, but that with Aliquat 336 increased up to 4 M, and decreased beyond that. Ruthenium extraction from 4.5 M NaCl solution using 25% Aliquat 336 and 20% TBP in kerosene was maximum and that from a 2 M NaCl solution using Alamine 336 was maximum. The extracted species for Alamine 336 and Aliquat 336 were R 3 NH + RuCl . and R 3 NCH RuCl , respectively. The effect of various diluents such as kerosene, benzene, toluene, xylene, hexane, and cyclohexane on extraction of ruthenium was studied. The extraction isotherm with 25% Aliquat 336 indicated quantitative extraction in two stages both at O:A ratio of 1:1 and 2:1. The thermodynamic parameters such as ΔH, ΔG, and ΔS were also determined.

Developing a Thermodynamical Method for Prediction of Activity Coefficient of TBP Dissolved in Kerosene

Results of the experimental measurements on the partial molar volume of kerosene used as a medium for dissolving TBP are utilized to determine the activity of TBP in the binary kerosene-TBP solution through the application of Gibbs-Duhem equation. The treatment is based on combination of the experimental data with the thermodynamic values available on the compressibility factor of pure kerosene at room temperature. It is shown that the activity of TBP in kerosene has a positive deviation from ideality with an activity coefficient derived as follows:1) at X TBP ≤ 0.01: γ TBP = 42.530, 2) at the 0.01 X TBP 0.2: 3) at the higher TBP concentrations 0.2 X TBP 0.97: and 4) at TBP Raoultian concentrations 0.97 ≤ X TBP:γ TBP = 1. These quantities can be utilized at temperature closed to 298 K.

Simultaneous spectrophotometric determination of uranium, nitric acid and nitrous acid by least-squares method in PUREX process

Multi-wavelength linear regression spectrophotometry combined with method of least squares for simultaneous determination of uranium, nitric acid and nitrous acid in PUREX (Plutonium/URanium EXtraction) process was developed. The molar absorbance matrix was calibrated with absorbance data measured in the wavelength range of 350–500 nm for a series of standard solutions by linear least-squares regression. This method used information from the absorption spectra of U(VI)–nitrous acid–nitric acid solutions to determine U(VI), nitrous acid and nitric acid. In the range of 0.95–74.1 g/L U(VI), 5 × 10−4–2 × 10−3 mol/L nitrous acid and 3–5 mol/L aqueous nitric acid solution, the measuring precision for determination of U(VI), nitrous acid and nitric acid was 0.46, 4.09, and 0.68 % respectively. In the solution of 30 % TBP–kerosene, the measuring precision for determination of U(VI) and nitrous acid was 0.42 and 4.2 % respectively in the range of 0.95–74.1 g/L U(VI) and 5 × 10−4–2×10−3 mol/L nitrous acid. The spectrophotometric method can be valuable for monitoring and controlling of both species in PUREX process operation, thanks to its simplicity, efficiency and accuracy.

Recovery of americium from analytical solid waste containing large amounts of uranium, plutonium and silver

Trace metallic impurity analysis by spectroscopic techniques is one of the important steps of chemical quality control of nuclear fuel materials. Depending on the burn-up and the storage time of the fuel, there is an accumulation of 241Am in plutonium based fuel materials due to β decay of 241Pu. In this paper, attempts were made to develop a method for separation of 241Am from 1.2 kg of analytical solid waste containing 70% U, 23% Pu, 5% Ag and 1–2% C as major constituents along with other minor constituents generated during trace metal assay of plutonium based fuel samples by d. c. arc carrier distillation atomic emission spectrometry. A combination of ion exchange, solvent extraction and precipitation methods were carried out to separate ~45 mg of 241Am as Am(NO3)3 from 15 L of the analytical waste solution. Dowex 1×4 ion exchange chromatographic method was used for separation of Pu whereas 30% TBP–kerosene was utilized for separation of U. Am was separated from other impurities by fluoride precipitation followed by conversion to nitrate. The recovery of Pu from ion exchange chromatographic separation step was ~93% while the cumulative recovery of Am after separation process was found to be ~90%.

Innovative approach to enhance uranium ion flux by consecutive extraction via hollow fiber supported liquid membrane

The enhancement of liquid membrane performance in this study, by consecutive extraction using a synergistic extractant, is the first to demonstrate that the synergistic extractant, normally employed in the solvent extraction process, can also be extended to extraction applications via a liquid membrane. The study focuses on increasing the flux of metal ions using a consecutive extraction reaction which occurs inside the liquid membrane phase. Uranium ions in trisodium phosphate solution, a by-product of monazite processing, are the specie of interest in this experiment. The feed solution is trisodium phosphate containing uranium ions, whereas the stripping solution is nitric acid. The extractant is Aliquat336 mixed with TBP in kerosene. The results demonstrate that when Aliquat336 is mixed with TBP, the flux of uranium ions is synergistically increased because of a consecutive extracting reaction in the liquid membrane phase. The highest flux is 3600 mg m −2 s −1 with 0.06 M TBP and 0.6 M Aliquat336. Synergistic extraction is also obtained because the flux is much higher than that obtained using a single extractant.

Hydrothermal synthesis of nanosized anatase TiO<SUB align="right">2: photocatalytic activity

Phase–pure anatase TiO2 nanocrystallites (620 nm) were synthesised from amorphous titania by hydrothermal process under relatively low temperatures (413453 K) in the presence of water. The precursor used for the hydrothermal synthesis was obtained by the precipitation stripping of the TiCl4 loaded organic solvent (tributylphosphate = TBP). TiCl4 was selectively extracted from the synthetic waste chloride liquors of titania industry by solvent extraction using TBP in kerosene as an extractant. The synthesised anatase TiO2 powders were characterised by XRD, SEM, IR and BET surface area. The influence of hydrothermal treatment conditions on the formation features, phase composition, particle size, morphology and properties of the products were investigated and discussed. The fact that the nucleation of anatase was accelerated by the presence of water suggested that water bonding with the surfaces of the primary particles of the amorphous titania forces the TiO6 octahedra units to rearrange to the anatase structure and acts as a catalyst for the structural rearrangement. The crystal growth of TiO2 to phase–pure anatase was proposed to proceed by face–sharing process through dissolution–precipitation of the dissolved TiO6 octahedra from the amorphous phase. It is evident from the XRD patterns that neither rutile nor brookite phases are present in the hydrothermally synthesised anatase TiO2 powders. Application of these nonocrystallites as photocatalyst was evaluated by photocatalytic degradation of methyl orange in water. The photocatalytic activity of anatase TiO2 was also compared with that of commercial photocatalysts, Hombikat UV 100 and Degussa P25.

The application of N,N-dimethylhydroxylamine as reductant for the separation of plutonium from uranium

Both single stage and multi-stages experiments on stripping plutonium with N,N-dimethylhydroxylamine (DMHAN) as reductant with methylhydrozine (MMH) as supporting reductant were carried out. The effect of contact time, temperature, acidity, concentration of DMHAN on back-extraction rate of plutonium was investigated in the single stage experiment. The results demonstrated that the reaction of stripping Pu(IV) in the organic phase (30% TBP–kerosene) 1BF solutions by DMHAN exhibits excellent stripping efficiency. Under the given conditions, the back-extraction rate of plutonium reaches 90% within 2 min. Higher temperature, lower acidity and the increased concentration of DMHAN benifit the stripping reaction. The concentration profile of HNO3, uranium and plutonium were determined in a multi-stages mixer-settler after the steady state of the back-extraction, and the multi-stages results show that the plutonium can be separated effectively from uranium. The recovery of plutonium and uranium reach 99.995% or over 99.99% respectively. The separation factor of U from Pu (SFPu/U) is about 2 × 104.

Synergistic separation of yttrium ions in lanthanide series from rare earths mixture via hollow fiber supported liquid membrane

Separation of yttrium ions from the mixture of rare earths in lanthanide series has been examined by a microporous hydrophobic hollow fiber supported liquid membrane. Cyanex 272 and TBP in kerosene are used separately as an extractant. Nitric acid solution is used as a stripping solution. Increasing the concentration of Cyanex 272 increases the percentages of extraction and stripping of yttrium from rare earths but slightly percentages are obtained by TBP. Interestingly, when TBP is added with Cyanex 272, the percentages of extraction and stripping increases. This is due to the synergistic effect of the extractants. Moreover, yttrium can be selectively extracted and stripped more than other lanthanide ions because the equilibrium constant decreases with an increase in atomic number or decreases with the ionic radius of the lanthanides. In other words, yttrium is separated selectively due to the smallest ionic radius while other lanthanides are separated with a decrease in ionic radius or an increase in atomic number.

Studies on the Selective Separation of Ir(IV), Ru(III) and Rh(III) from Chloride Solutions using Alamine 336 in Kerosene

The liquid–liquid extraction of Ir(IV), Ru(III), and Rh(III) from chloride solution was studied under different conditions of aqueous‐ and organic‐phase component concentrations using Alamine 336 (A336) as an extractant. The differences obtained in the extraction of individual metals at different concentrations of A336 and HCl in the organic and aqueous phases respectively were used to mutually separate the three metals. A two‐step separation scheme was proposed. In the first step, Ir(IV) was selectively extracted using a solvent comprised of 0.1% A336 and 10% TBP in kerosene. In the second step, Ru(III) was quantitatively extracted using a solvent comprised of 5% A336 and 10% TBP in kerosene (all % v/v). Rh(III) was selectively left behind in the raffinate. Under controlled experimental conditions, we were able to eliminate the base metal ions commonly associated with Ir, Ru, and Rh during the extraction and the stripping process.

Modification in Purex process using supported liquid membrane separation of cerium(III) via oxidation to cerium(IV)from fission products from nitrate medium by SLM

The separation of cerium from fission products during Purex process have been achieved successfully. Cerium(III) has been oxidized to Ce(IV) by 9 M HNO 3 and 2 M NaBrO 3, Ce(IV) was stable for a long time (6 months) and separated from Uranium(IV) completely. The separation factor was found to be 3. The effect of 30% TBP–kerosene and different cations, Zr(IV) and Mo(VI) using supported liquid membrane on the extraction process have been studied. The effect of temperature has been studied and the activation energy of the reactions has been evaluated to be 19.04, 12.01 kcal/mol for Ce(III) and Ce(IV), respectively, which suggested that this process is chemical reaction controlled under this hydrodynamic condition. The membrane stability has been studied for a long time pertraction and in terms of adsorbed doses demonstrates the stability of membrane in such systems.

Kinetic studies on the extraction of U(IV) by TBP in kerosene from nitrate medium

The kinetics of extraction of U(IV) by TBP in kerosene was investigated using a stirred Lewis cell. The effect of the different parameters affecting the extraction rate as well as temperature were separately investigated. The rate equation deduced from the experimental results show that the extraction of U(IV) is first order dependent on TBP concentration while it is of zero order with respect to U(IV), H+, NO 3 − and HNO3 concentrations. The data obtained show that the extraction process is governed by chemical reactions taking place at teh interface.

Influence of process re-extraction-crystallization parameters on the properties of ammonium uranyl-tricarbonate crystals

The purpose of this work is the preparation of ammonium uranyl-tricarbonate (AUC) crystals by means of direct re-extraction-crystallization from the uranium loaded organic phase (30% TBP in kerosene) making use of ammonium carbonate. The re-extraction-crystallization tests were carried out in batches. Some physical parameters, such as the re-extractant concentration, the ratio (O/A) of the flow rate of the organic phase to that of the aqueous, the residence time, and the temperature, which directly affect the crystal properties, were studied.