Mixture Of TBP 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.

Extraction of H3PO4 from low-grade phosphate rocks leachate of HCl-route by the mixture of TBP and IPE: Optimization, mass transfer and mechanism

The mixed solvent of tributylphosphate and isopropyl ether was used to extract H3PO4 and separate Ca2+ and Cl− from low concentration wet process phosphoric acid prepared by low-grade collophane and 30 wt% hydrochloric acid solution. Then, the effects of extraction temperature, composition of solvent mixture, aqueous/organic phase ratio, extraction time and extraction stage were investigated, respectively. The result shows that the extraction process of H3PO4 is an exothermic process and the enthalpy changes (ΔH) is −12.50 kJ mol−1. The McCabe–Thiele diagram shows two counter-current stages achieves about 76.9 wt% H3PO4 extraction at 293 K. Based on the mass transfer theory of liquid–liquid extraction, extraction yields for all tested component were summarized as an exponential function of cross-flow extraction stages. Meanwhie, extraction mechanism studies show that the comlex of αH3PO4 βTBP was formed in extraction process and higher Ca2+ concentration was beneficial for H3PO4 extraction. Meanwhile, the effects of stripping temperature, aqueous/organic phase ratio and stripping time on the re-extraction performance of H3PO4, Ca2+ and Cl− were studied, respectively. The result of experiment will provide some theoretical support for the industrial application of HCl-route wet process phosphoric acid on low-grade phosphate rock and phosphate tailings.

Separation of molybdenum and tungsten from iron in hydrochloric-phosphoric acid solutions using solvent extraction with TBP and P507

A mixture of TBP and P507 was proposed for the separation of molybdenum (Mo) and tungsten (W) from iron (Fe) in a hydrochloric-phosphoric acid (HCl-H3PO4) solution that was obtained from the hydrochloric acid preleaching of low-grade scheelite. Various extractants with TBP were investigated, and P507 showed synergistic effects on Mo and W extraction and a strong antagonistic effect on Fe extraction. Then, the effects of various conditions on the separation of Mo and W from Fe with the mixture of TBP and P507 were investigated. Using 24% (v/v) TBP, 16% (v/v) P507 and 60% (v/v) kerosene as extractants, 90% Mo and 88% W were extracted with only 8% Fe co-extraction, and the separation factors of Mo/Fe and W/Fe were 153 and 118, respectively, through one-stage extraction under the following conditions: 1.7 mol/L H+, A/O ratio of 3:1, contact time of 10 min, and temperature of 15 °C. After two-stage batch continuous extraction, 99% Mo, 94% W and 10% Fe were extracted. By washing with 2 mol/L hydrochloric acid, most of the Fe and other impurities were removed with negligible losses of Mo and W. Upon stripping with 5 mol/L ammonia at a 1:1 organic-to-aqueous phase ratio, almost 100% of the Mo and W were recovered from the washed organic phase. Other impurities, such as P, Si, Ca, Al, and Mn, minimally affected the extraction of Mo and W.

Exothermic Processes in Mixtures of TBP with Uranyl Nitrate

The thermal stability of mixtures of TBP and its solutions in diluents with uranyl nitrate (UN) at 150–200°C was evaluated. Exothermic self-accelerating oxidation processes (thermal explosions) arise in mixtures with TBP at 160–170°C. In mixtures of UN with solutions of TBP in diluents, the intensity of the exothermic processes is appreciably lower. The presence of the extractant in UN solutions fed to high-temperature operations gives rise to the hazard of the initiation of intense exothermic processes.

Intensification of zirconium and hafnium separation through the hollow fiber renewal liquid membrane technique using synergistic mixture of TBP and Cyanex-272 as extractant

Abstract The novel synergistic mixture of TBP and Cyanex-272 is used as the extractant in the hollow fiber renewal liquid membrane (HFRLM) technique for Zr/Hf separation. The effects of the chemical and operational parameters such as HNO3 concentration in the donor phase, NH4F concentration in the acceptor phase, Cyanex-272 and TBP concentration in the liquid membrane phase, the lumen and shell side flow rates, and aqueous/organic volume ratio on the mass transfer and separation performance of HFRLM method were investigated. The obtained results reveal the intensification potential of proposed HFRLM technique for selective extraction of Zr over Hf with separation factor higher than 100. The HFRLM method provides two times higher mass transfer flux in comparison with hollow fiber supported liquid membrane (HFSLM). Also, the HFRLM method shows satisfactory stability for 700 min of continuous operation. The Zr ion transport through the LM phase follows the coupled co-transport mechanism and the diffusion in the renewal layer is recognized as the rate-controlling step in the HFRLM process. Moreover, the Zr mass transfer coefficient and molar flux in the HFRLM method are calculated in the range of 1 × 10−8 to 8.4 × 10−7 m·s−1 and 4.9 × 10−6 to 20.1 × 10−6 mol·m−2·s−1, respectively.

Exothermic processes in mixtures of TBP with nitric acid

Causes of initiation of exothermic self-accelerating oxidation processes in mixtures of TBP with HNO3 are analyzed. The main condition is heating of the mixtures to temperatures (Т st) above which the heat release in the chemical reaction starts to exceed the heat removal from the system. After the initiation of selfaccelerating exothermic reactions, their development and intensity depend on whether the vessels are sealed, on the HNO3 concentration, and on the heating time. Heat treatment and radiolysis of the extractant slightly decrease Т st of its mixtures with HNO3 compared to the values for the “fresh” extractant.

Studies on Pu238 induced alpha radiolysis of the solvent TBP

Radiolysis and degradation of a 30 % volume mixture of TBP in n-dodecane has been studied by means of alpha radiation from Pu238. Radiolysis effects are quantitatively estimated by the percent of Pu238 retained in the irradiated organic phase after the washing procedure. The effects of radiation dose, nitric acid concentration, and the presence of UO2 2+ and Zr4+, have been investigated. The results indicate that Zr4+ accelerates the alpha-particle degradation of the organic phase, and that both UO2 2+ and Pu4+ complex with the degradation products formed by the absorbed radiation.

Volumetric and compressibility studies on extractant-diluent system: effect of chain length

The experimental densities ρ and sound velocities u for binary mixtures of TBP–dodecane have been measured at temperatures from 298.15 to 323.15 K and atmospheric pressure over the whole mole fraction range. From these data, the excess molar volume (VE) and deviation in isentropic compressibility (Δks) have been calculated and fitted to Redlich–Kister polynomial equation. VE and Δks values are positive for TBP–dodecane over the whole mole fraction range and at the above-mentioned temperatures. Excess thermal expansion coefficients (αE) of a mixture of equimolar composition and deviations in molar volume of the components at infinite dilution have been calculated at all temperatures. The variations of these properties with composition and temperature of the binary mixture are discussed in terms of molecular interactions.

Separation of zirconium and hafnium by solvent extraction using mixture of TBP and Cyanex 923

In this study, a new Zr/Hf separation procedure by solvent extraction is proposed. The method is based on using the mixture of TBP and Cyanex 923 as extractant in the organic phase. Several parameters including; TBP/Cyanex 923 volume ratio, extractant concentration in the organic phase, nitric acid and NaNO 3 concentration in aqueous phase have been investigated. The results demonstrate better condition respect to traditional TBP/HNO 3 process. Lower required acid concentration and more zirconium extraction are some advantages of the new separation process.

Geometric Isomerism in Pentacoordinate Cu2+ Complexes: Equilibrium, Kinetic, and Density Functional Theory Studies Reveal the Existence of Equilibrium between Square Pyramidal and Trigonal Bipyramidal Forms for a Tren-Derived Ligand

A ligand (L1) (bis(aminoethyl)[2-(4-quinolylmethyl)aminoethyl]amine) containing a 4-quinolylmethyl group attached to one of the terminal amino groups of tris(2-aminoethyl)amine (tren) has been prepared, and its protonation constants and stability constants for the formation of Cu(2+) complexes have been determined. Kinetic studies on the formation of Cu(2+) complexes in slightly acidic solutions and on the acid-promoted complex decomposition strongly suggest that the Cu(2+)-L1 complex exists in solution as a mixture of two species, one of them showing a trigonal bipyramidal (tbp) coordination environment with an absorption maximum at 890 nm in the electronic spectrum, and the other one being square pyramidal (sp) with a maximum at 660 nm. In acidic solution only a species with tbp geometry is formed, whereas in neutral and basic solutions a mixture of species with tbp and sp geometries is formed. The results of density functional theory (DFT) calculations indicate that these results can be rationalized by invoking the existence of an equilibrium of hydrolysis of the Cu-N bond with the amino group supporting the quinoline ring so that CuL1(2+) would be actually a mixture of tbp [CuL1(H(2)O)](2+) and sp [CuL1(H(2)O)(2)](2+). As there are many Cu(2+)-polyamine complexes with electronic spectra that show two overlapping bands at wavelengths close to those observed for the Cu(2+)-L1 complex, the existence of this kind of equilibrium between species with two different geometries can be quite common in the chemistry of these compounds. A correlation found between the position of the absorption maximum and the tau parameter measuring the distortion from the idealized tbp and sp geometries can be used to estimate the actual geometry in solution of this kind of complex.

Synergistic Extraction of Zn(II) by Mixtures of Tri-Butyl-Phosphate and Trialkyl Amine Extractant

The extraction of Zn 2+ by mixtures of tri-butyl-phosphate (TBP, B) and trialkyl amine (N235, R 3N, R = C 8–C 10) has been carried out. The mixtures have evident synergistic effects on Zn 2+ with a synergistic enhancement factor of 12.34. The extraction mechanism was studied using the methods of slope analysis and constant mole. The extracted complex is determined as (R 3N) 1.5·ZnCl 2·B. The extraction reaction is as the following: ZnCl 2 ( a ) + 1.5 R 2 N ( 0 ) + B ( 0 ) ⇌ ( R 3 N ) 1.5 ⋅ ZnCl 2 ⋅ B ( 0 ) The equilibrium constant and thermodynamic functions, Δ H, Δ G, and Δ S have been calculated, indicating that the reaction is exothermically driven. The extraction of Zn 2+ and Cd 2+ by the mixtures of TBP and N235 or N,N-di(1-methyl-heptyl) acetamide (N503) was also conducted. The results show that the mixtures of TBP and N235 do not have evident synergistic effects on Cd 2+, while TBP-N503 mixing systems have similar effects on neither Zn 2+ nor Cd 2+. Moreover, the separation factors of Zn 2+ and Cd 2+ by TBP-N235 system was studied. It is feasible and advantageous to separate Zn 2+ from bulk cadmium solutions.

Leachability of metals from fly ash: leaching tests before and after extraction with supercritical CO 2 and extractants

Residues such as sewage sludge or fly ashes are usually contaminated with toxic heavy metals. These metals leach out after contact with water, thus polluting the groundwater. If aqueous concentrations of metals are exceeded, these residues require expensive disposal. Supercritical fluid extraction (SFE) is a promising method to reduce the metal content of contaminated particles to such an extent that leachability is reduced and the demands of legislation are observed. This paper focuses on the metal leachability and the effect after extraction in a 12-L revolving vessel with supercritical CO 2 with fly ash from a municipal waste incinerator as model compound. Pre-leaching with water prior to SFE led to the removal of water-soluble compounds and structural changes on the ash surface. Standard leaching tests of fly ash after SFE with Cyanex 302, TBP, D2EHPA, or mixtures of TBP–D2EHPA focussed on metals such as Zn, Pb, Mn, Cd, Cu, V, Sb, Ni, Mo, Cr, and Co. The leaching test showed a leachability increase of Sb and the successful reduction in leachability of Zn, Pb, and Mn in particular.

Evaluation of Excess Gibbs Energy of Mixing in Extremely Dilute in Nonpolar Solvents Solutions of TRI-N-Butyl Phosphate

The excess gibbs energy of mixing in binary mixtures of TBP in nonpolar solvents viz. bcnzene, carbon disulphide, cyclohexane, n-heptane, n–hexane, p–xylene, tetrachloromethane at temperature 303°K is studied. The excess free energy of mixing (AGA8) is in the order, n–hexane < n–heptane < benzene < cyclohexane < p–xylene < CCI4 < CS2. The results corroborate the findings obtained through evaluation of the excess correlation Factor.

Model for single or multiple fires in a ventilated system: code development

The primary thermodynamic consequences of a fire in a room are evaluated through a “multi-zones” model. FLAMME 1, the basic software package, describes and calculates for a single source the transient thermodynamic state of the various components within a closed or a ventilated room. The spread of fire to another fuel stimulated as an internal structure is only indicated by an ignition test based on the temperature of this structure. The model applies to any number of local ventilation devices. Gas venting is estimated as a flux through a hole or through a stack; furthermore, FLAMME package could be coupled to a ventilation design code involving complex network. Validation of FLAMME 1 is based on experience with pool combustion for a mixture of TBP and kerosene. Investigations are currently under way for PMMA and bituminen combustion. FLAMME 2, being developed, shows a way to extend the application range to sequential or simultaneous fire development from several sources of various materials. Some problems will arise in the modelling of radiative heat exchanges and validation will run into difficulties due to the lack of adequate automatic control experience with multiple fuel fires.

Behaviour of transplutonium and rare earth elements on TVEX

Behaviour of transplutonium and rare-earth elements on TVEX, containing TBP, HDEHP, mixture of TBP∶HDEHP (1∶1), PAPNA and TOA has been studied. The analytical possibility of isolation and separation of tetravalent Pu and Bk from trivalent actinides and lanthanides from strong nitric acid solutions (1.0–12.0) on TVEX with TBP, POR, HDEHP and TOA has been demonstrated. The separation of trivalent Bk, Cf and Eu from Am and Cm is real on TVEX, containing HDEHP and mixture of TBP∶HDEHP.

Uranium(VI) extraction from acid mixtures with organophosphorus esters

The extraction of uranium(VI) from acidic mixtures of H 3PO 4 and HNO 3 with neutral (TBP and TOPO) and acidic (D2EHPA) organophosphorus esters is reported. Experiments were performed with pure TBP, TOPO and D2EHPA and with mixtures of TBP and D2EHPA, and TOPO and D2EHPA. When pure TOPO is used as extractant, species such as UO 2(NO 3) 2 · 2TOPO are formed. Using pure D2EHPA, the existence of UO 2X 2(HX) 2 is shown (HX = D2EHPA). D2EHPA co-extracts small amounts of HNO 3 or NO 3 − ions. Mixtures of TOPO and D2EHPA show synergic properties and evidence is given for the species UO 2X 2(HX) 2 · TOPO. Synergic effects between TBP and D2EHPA are also considered.

THE EXTRACTION OF Am(III) FROM NITRIC ACID BY OCTYL(PHENYL)-N,N-DIISOBUTYLCARBAMOYLMETHYLPHOSPHINE OXIDE - TRI-n-BUTYL PHOSPHATE MIXTURES

Abstract The extraction behavior of Am(III) from nitric acid by octy1(phenyl)-N,N-diisobutylcarbamoyl methyphosphine oxides, OØD[IB]CMPO, in the presence of tributylphosphate, TBP, has been studied using diethylbenzene, decalin, and normal aliphatic hydrocarbon diluents. Relative to ØD[IB]CMPO alone, mixtures of TBP and OØD[IB]CMPO show a slight enhancement in the extraction of Am(III) from nitric acid solution above 2 M and a moderate decrease in extraction for lower acid concentrations. The net effect of TBP addition to OØD[IB]CMPO (as well as other selected carbamoyl methylphosphoryl extractants) is a relative insensitivity of the distribution ratio of Am(III) to HNO3 concentration in the range of 0.5 M to 6 M and facilitated stripping of Am(III) with dilute acid. Since a continuous variation study of Am(III) extraction using mixtures of ØOD[IB]CMPO and TBP at a fixed total concentration revealed no evidence of a mixed complex, the TBP appears to be behaving primarily as a phase modifier The most significant benefit gained from addition of TBP to ØD[IB]CMPO is the increased metal ion loading capacity and extractant compatibility with alicyclic and aliphatic diluents. The use of TBP to overcome phase compatibility with other bifunctional extractants of the carbamoylmethylphosphoryl type and the use of other phase modifiers with ØD[IB]CMPO have also been investigated.

The Synergistic Extraction of Sm(NO3)3and Gd(NO3)3by a Mixture of Tributyl Phosphate and Aliquat 336 in AMSCO and Ammonium Nitrate Medium

Abstract The synergic extraction of Sm and Gd using a mixture of tri-butyl phosphate and Aliquat 336 is presented. The influence of diluents, salting out agents and acidity on the synergic extractions have been investigated. The separation factor of Sm and Gd was found to be larger than 3. This is one of the best systems for the separation of Sm and Gd. NH4NO3 was found to be extracted by pure TBP or pure Aliquat 336, but cannot be extracted by a mixture of TBP and Aliquat 336.