Solvent extraction of uranium(VI) with DI-2-ethylhexyldithiophosphoric acid from aqueous nitrate,chloride, sulfate and phosphate media

The extraction of uranium(VI) with di-2-ethylhexyldithiophosphoric acid (HEhdtp) in benzene from aqueous solutions containing nitrate, chloride, sulfate and phosphate anions was investigated. The data obtained show hat the mechanism of extraction is similar to that established for perchlorate media. The inorganic anions present in the aqueous phase do not participate in the extraction process but affect the magnitude of the distribution ratio by the complexation phenomena which occur in the aqueous phase. In benzene the extracted species is a 12 complex of uranium(VI) with HEhdtp.     

D2HEDTPA和D2EHPA萃取汞(II)的研究

The extration of Hg2+ from HNO3 solution with (D2EHPA) and bis(2-ethylhexyl dithiophosphate (D2EHDTPA) was studied. The composition of extracted complex was determine by saturation and mol. ratio methods. The bonding of the extracted species is discussed on the basis of IR and NMR data. EHMO calcns. show that the extration capacities of the 2 extractants for Hg2+ are quite different.     

Extraction of uranium (VI) from sulfuric acid solution with TOPO

The extraction of uranium(VI) from sulfuric acid medium with tri-octylphosphine oxide (TOPO) in n-heptane was studied. Accompanied with the increase in the concentration of H₂SO₄, the distribution coefficient of uranium(VI) increased in the region of dilute sulfuric acid. When the concentration of H₂SO₄ surpassed 3.5 mol·dm⁻³, the distribution coefficient of uranium(VI) was at maximum. This result was due to the competition extraction between uranium(VI) and H₂SO₄. From the data, the composition of extracted species and the equilibrium constant of extraction reaction have been evaluated, which were (TOPOH)₂UO₂(SO₄)₂ (TOPO) and 10^7.6±0.15, respectively.     

Extraction and separation studies of uranium/VI/with tris-/2-ethyl hexyl/phosphate

A solvent extraction method is proposed for the extraction and separation of uranium from salicylate media using tris-/2-ethyl hexyl/ phosphate dissolved in xylene as an extractant. The optimum conditions were evaluated from a critical study of pH, salicylate concentration, extractant concentration, period of equilibration and diluent. The method permits the separation of uranium from thorium, cerium, titanium, zirconium, hafnium, copper, vanadium and chromium from binary mixtures and is applicable to the analysis of uranium in synthetic samples. The method is precise, accurate, fast and selective.     

Extraction of uranium/VI/ with octylphenyl acid phosphate from nitric acid solutions and its separation from some trivalent lanthanides

Mössbauer spectra of hexakis/alkylurea/iron/III/ complexes were measured to investigate the paramagnetic relaxation in ionic compounds. The effects of iron-iron distance and temperature on Mössbauer line shape were studied in these compounds, and the results are discussed in comparison with our previous data on tris/\-diketonato/iron/III/.     

Extraction and spectrophotometric determination of uranium(VI) withN-phenylcinnamohydroxamic acid

Uranium(VI) reacts withN-phenylcinnamohydroxamic acid to form an orange-yellow complex in the pH range 5.5–8.5. The orange-yellow complex, having the composition of 12 (metal:ligand), is quantitatively extractable into ethyl acetate. The spectrum of the complex exhibits a maximum absorption at 400 nm with a molar absorptivity of 6500 M^–1·cm^–1. The coloured system obeys Beer's law in the concentration range 2–40g·ml^–1 of uranium(VI). The photometric sensitivity of the colour reaction is 0.037 g·cm^–2 of uranium(VI). Most of the common ions do not interfere and the method has been found to be simple, precise, and free from the rigid control of experimental conditions. The method has been applied to the determination of uranium in synthetic matrices and potable water.     

Extraction chromatographic separation of uranium and fission products in the system di-(2-ethylhexyl)phosphoric acid-hydrochloric acid

An elution scheme has been developed for obtaining separate fission product and uranium fractions using extraction chromatographic techniques with di-(2-ethylhexyl)phosphoric acid as a stationary phase and HCl of varying concentration as eluting agent. The investigations have been concentrated on the fission products cerium, europium, molybdenum and zirconium. The elution of zirconium by oxalic acid is characterized by a peak broadening and has been explained by considering extraction kinetics. Experiments on column performance with different support materials have proved Ftoroplast-4 and Celite Hyflo Super Cel to be capable of giving column fillings with equal separation ability.     

Extraction of carpathian menilite shales with organic solvents

Extraction of Carpathian menilite shales with 18 solvents at 20°C was examined.     

Extraction of uranium(VI) from nitric acid solution with hexyloctylsulfoxide (HxOSO)

The thermodynamic extraction of uranium(VI) with hexyloctylsulfoxide (HxOSO) has been studied. It was found that the distribution ratio increases with increasing nitric acid concentration up to 2.3 mol/l and then decreases. The distribution ratio also increases with increasing extractant concentration. The extracted species appears to be UO₂(NO₃)₂ ^.2HxOSO. The influences of temperature, sodium nitrate and oxalate concentrations on the extraction were also investigated, and the thermodynamic functions of the extraction reaction were obtained.     

Kinetic studies on the extraction of uranium(VI) from phosphoric acid medium by bulk liquid membrane containing di-2-ethylhexyl phosphoric acid

To go through the first stage of industrial solvent extraction process in order to recover uranium from phosphate rocks by liquid membrane techniques, as a simple model, the kinetics of facilitated transport of uranium(VI) from a dilute phosphoric acid medium into more concentrated phosphoric acid media as a receiving phase through a bulk liquid membrane containing di-2-ethylhexyl phosphoric acid as a carrier was studied. The influence of phosphoric acid concentration in the source and receiving phases, carrier concentration, type of solvent, stirring speed and temperature were investigated. The kinetic parameters (k _e, k _s, t _max, J _max) were calculated for the interface reactions assuming two consecutive, irreversible first-order reactions. The activation energy values were calculated as 29.40 and 19.51 kJ mol^?1 for extraction and stripping, respectively. The values of calculated activation energy indicated that both the extraction and stripping processes were controlled by mixed regime (both kinetic and diffusion). In addition, the influence of adding trioctyl-phosphine oxide into the membrane phase as a synergic agent on the transport kinetics was determined.     

Interaction of uranium(VI) with phthalic acid

Phthalic acid, a ubiquitous organic compound found in soil, water, and in domestic and nuclear wastes can affect the mobility and bioavailability of metals and radionuclides. We examined the complexation of uranium with phthalic acid by potentiometric titration, electrospray ionization-mass spectroscopy (ESI-MS), and extended X-ray absorption fine structure (EXAFS) analysis. Potentiometric titration of a 1:1 U/phthalic acid indicated uranyl ion bonding with both carboxylate groups of phthalic acid; above pH 5 the uranyl ion underwent hydrolysis with one hydroxyl group coordinated to the inner-sphere of uranium. In the presence of excess phthalic acid, ESI-MS analysis revealed the formation of both 1:1 and 1:2 U/phthalic acid complexes. EXAFS studies confirmed the mononuclear biligand 1:2 U/phthalic acid complex as the predominant form. These results show that phthalates can form soluble stable complexes with uranium and may affect its mobility.     

Complexation of uranium(VI) with acetohydroxamic acid

The advanced separation extraction process based on tri-n-butyl phosphate organic phase called UREX is being developed to separate uranium from fission products and other actinides, and the acetohydroxamic acid (AHA) is employed to reduce and complex plutonium and neptunium in order to decrease their distribution to the TBP-organic phase. In this study, the extraction of uranium was performed from various aqueous matrices with different concentrations of HNO₃, LiNO₃, and AHA. Extraction of uranium increases with increasing both initial HNO₃ and total nitrate concentration. UV-VIS spectrophotometry confirmed that AHA is involved in the complex of uranium with TBP.     

Sulfation of dextran with chlorosulfonic acid in organic solvents

Solutions of chlorosulfonic acid in dichloroethane and formamide are suggested for incorporation of sulfo groups into macromolecules of polysaccharides. The influence of temperature, reaction duration, and reactant ratio on the yield of sulfated dextran and also the influence of the reaction conditions on hydrolytic stability of the polymer were studied.     

Extraction-spectrophotometric determination of uranium/VI/ with tropolone

Tropolone reacts with uranium/VI/ and forms orange yellow precipitate extractable in chloroform. The maximum absorption occurs at 405 nm and the absorbance is found to remain constant in the pH range of 5.5 to 7.0. Beer's law is obeyed upto 37.6 ppm of U/VI/. The sensitivity of the colour reaction is 0.034 g cm^–2. Most of the common ions do not interfere. The method becomes more selective by masking some of the interfering cations with EDTA. The method was applied to determine uranium in monazite sand.This work is a part of the Ph.D. Thesis.     

Extraction of uranium(VI) from nitric acid solution by N,N-dibutyldodecanamide

The partition of uranium(VI) between nitric acid solutions and solutions of N,N-dibutyldodecanamide (DBDA) in kerosene has been investigated at varying concentrations of nitric acid, extractant, salting-out agent LiNO₃ and at different temperatures. The mechanism of extraction is discussed in the light of the results obtained.     

Extraction of uranium(VI) with octyldodecylsulfoxide (ODoSO)

Complexes of Hf with polyaminopolycarboxylic acids viz. diethylene-triamine-penta-acetic acid (DTPA) and its dimethoxy derivative DMDTPA have been studied using paper chromatography at different acidities. Kinetic stabilities of the complexes have also been looked at. Behaviors of these two ligands in complexing with Hf(IV) have been found to be similar. The extent of complexation reduces slowly with acidity and increase with time and reaches a maximum around 70-80% after about 24 hours.