Successive uranium and thorium adsorption from Egyptian monazite by solvent impregnated foam

The present work deals with uranium and thorium recovery from the Egyptian monazite sulfate leach liquor using the extraction chromatography technique (solvent impregnated material), where tributylamine (TBA) and di-n-octylamine (DOA) solvents were impregnated onto foam uranium and thorium separate recovery. The calculated theoretical capacities of the latter solvents were about 1.4 gU/g foam and 1.6 gTh/g foam, respectively. The attained uranium and thorium adsorption efficiencies (using ion-exchange columnar technique) were about 75 and 70% of its theoretical capacities, respectively. Using 1 M NaCl–0.1 M H₂SO₄ and 2 M H₂SO₄ as eluent solutions for uranium and thorium from the loaded solvents impregnated foam gave 95.8 and 98.7% elution efficiencies, respectively.     

Use of open-cell resilient polyurethane foam loaded with crown ether for the preconcentration of uranium from aqueous solutions

The preconcentration of uranium from aqueous solutions on open-cell resilient polyurethane foams (PUF) impregnated with crown ether as an organic extractant in different conditions was investigated. The data showed that 50 minutes is a sufficient time to attain equilibrium with a maximum extraction percentage for uranium ion on polyurethane foams loaded with crown ether. Also the extraction percentage of uranium is increased markedly with increasing the pH values up to pH ~ 6 and displayed the lowest extraction at 8>pH>6. The different isotherms of uranium sorption have shown that the sorption followed a Freundlich isotherm. Column studies have been carried out in order to extend these studies to the plant scale. From the data of column sorption and breakthrough curves, the height equivalent of theoretical plates (HETP), and breakthrough capacity which affect the efficiency of the column have been calculated and found to be 1.03 mm/plate, 64±5 and 58.3 mg uranium/gram polyurethane foam impregnated with crown ether, respectively.     

A continuous preconcentration of cobalt and uranium using liquid emulsion membranes

A continuous extraction device for preconcentration of metals with light phase internal recycle has been developed. This system was used for preconcentration of cobalt and uranium from 20–30 dm³ samples with 10.8 dm³/hours feed rate. The emulsion membranes were created of surfactants and LIX 64 N (for cobalt) or di-2ethylhexyl-phosphoric acid (for uranium) as a carrier to control stability and permeability for long time periods. The results from continuous extraction of cobalt and uranium using the device constructed have shown the possibility to reach 100–200-fold preconcentration of metals with high yield (min. 92%).     

Evaluation of a beta-diketone-imbedded polyurethane foam

A beta-diketone-imbedded polyurethane foam was made for the sorption of uranium from aqueous solutions. The incorporation of the beta-diketone functional group into the polyurethane foam was simple, and relatively inexpensive. The beta-diketone foam was ground to facilitate the evaluation of its ability to extract uranium from aqueous solutions with a wide range of temperature and pH values. The beta-diketone material showed superior extractability of uranium from solutions with pH 7 +/- 3. In general, the beta-diketone material showed greater extractability of uranium at all temperatures and pH values tested when compared to a blank polyurethane foam without the beta-diketone functional group.     

A Study on the extraction of uranium(VI) from sulphate leach liquor using LIX63

The sulphate leach liquor obtained from the sulphuric acid leaching process of Egyptian monazite was treated using solvent extraction to recover U(VI) by LIX63. The influence of various basic variables such as pH, concentration of LIX63, temperature, different stripping agent, phase ratio and diluents was examined. Using 10% LIX63 with the aqueous solution at equilibrium pH 5.5 and a phase ratio A/O?=?1/1, a four-stage McCabe-Thiele plot was constructed, which showed 85.57% of U(VI) extraction. The thermodynamic data showed that the extraction process is exothermic with enthalpy change ΔH?=???43.866?kJ/mol, the stripping of U(VI) was quantitative using 4?M HNO₃. The stable complex UO₂(HSO₄)R_org formed during extraction which supports the cation exchange mechanism was confirmed by FTIR spectral analysis. Uranium cake was finally obtained from the strip solution by the addition of hydrogen peroxide and ammonium hydroxide as precipitating agents, and a workable flowsheet was then formulated.     

Extraction of uranium from aqueous solution by phosphonic acid-imbedded polyurethane foam

Phenylphosphonic acid was imbedded into the matrix of the polyurethane foam during the fabrication process of the polymer. The extraction of uranium by phosphonic acid-imbedded polyurethane foam and blank polyurethane (i.e., foam without phosphonic acid functional groups) was investigated. Phosphonic acid-imbedded foam showed superior extractability of uranium from solutions with pH=7.0+/-1.5 over a wide range of temperature.     

Sorption behaviour of uranium(VI) with N,N-dibutyl-N'-benzoylthiourea Impregnated in Amberlite XAD-16

The sorption of U(VI) by N, N-dibutyl, N'-benzoylthiourea (DBBT) impregnated resin has been studied. DBBT impregnated resin was prepared by direct adsorption of chelating ligand onto macroporous support, Amberlite XAD-16. The adsorption of DBBT on the macroporous support is shown by FTIR spectroscopy to be the result of only weak chelating ligand-support interactions. Parameters such as the pH effect on the sorption of uranium, the sorption capacity of the impregnated resin, the stripping of uranium and the effect of coexisting ions were investigated by batch experiments. The results demonstrated that uranium(VI) ions, at pH 4.5-7 could be sorbed completely using 0.1 g Amberlite XAD-16 resin loaded with DBBT. The sorption capacity of the impregnated resin is 0.90 mmol uranium(VI) g(-1). Quantitative recovery of U(VI) is achieved by stripping with 0.1 M HNO(3). The method was applied to the determination of uranium in synthetic samples. The precision of the method was 2.4 RSD% in a concentration of 1.20 mug ml(-1) for ten replicate analysis.     

Performance Evaluation of Nickel Separation and Extraction Process from Simulated Spent Cr/Ni Electroplating Bath Solutions by ELM Process Using LIX63 and PC88A

The study was conducted to investigate synergistic extraction of nickel from simulated spent Cr–Ni electroplating bath solutions by emulsion liquid membrane (ELM) process using 5,8-diethyl-7-hydroxydodecan-6-one oxime (LIX 63) and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC88A) as carriers. The importance of ELM composition and the properties of simulated spent electroplating bath solution have been optimized to synergistically extract nickel. The important parameters affecting the nickel extraction efficiency and ELM stability, such as acid concentration, stripping solution type and concentration, extractant concentration, surfactant concentration, and phase ratio, were experimentally studied. Along with obtained results, higher than 99% of nickel was selectively extracted within 30 minutes from simulated electroplating bath solutions that their metal concentrations was in the range of 100–500 mg/L. in the optimum conditions. The higher separation factor value of nickel over chromium (β_Ni/Cr) was obtained as 898. As a result, the nickel extraction kinetic was found to depend on PC88A, since extraction mechanism of PC88A is slower than that of LIX63. So, the combined use of LIX63 and PC88A improved the selective extraction of nickel in that process.     

Extraction chromatography of uranium with dioctyl sulphoxide

Uranium(VI) is quantitatively extracted from aqueous perchlorate media into dioctyl sulphoxide in 1,2-dichloroethane. The extracted species contains four sulphoxides for each uranium. Most other metal ions are not appreciably extracted. On columns containing a solid support impregnated with dioctyl sulphoxide in 1,2-dichloroethane, uranium(VI) may be separated quantitatively from metal ions such as thorium(IV), zincronium(IV) and rare carths(III).     

The extraction of uranium from acidic solutions by Adogen impregnated open cell polyurethane foam sponge

Open cell polyurethane foam coated with long chain tertiary amines (Adogen) has been shown to be an effective extractant for uranium in acidic solutions (3>pH>1). With dodecyl alcohol present uranium extraction at pH<1 is effective. The coated foam allowed column flow extraction at high flow rates but capacity studies indicated that only a fraction (about 1/3 to 1/2) of the amine was available for the complexation of the uranium. Interference of some common metal cations indicated that only Co(II) showed a significant adverse effect on the uranium extraction.     

HDEHP-CMPO/SiO2-P: a promising solid-phase extractant for uranium recovery from different acidic media

Journal of Radioanalytical and Nuclear Chemistry - A novel macroporous silica-based HDEHP-CMPO impregnated polymeric solid-phase extractant showed an excellent uranium adsorption efficiency from...     

Liquid-liquid extraction of molybdenum(VI) and uranium(VI) by LIX 622

The order of extraction of Mo(VI) from 1M acid solutions by 5% (v/v) LIX 622 (HL) in benzene is HCl>HNO₃>HClO₄>H₂SO₄, and extraction decreases with increasing concentration of HCl and H₂SO₄, and increases slightly with increasing concentration of HNO₃ and HClO₄. The extracted species is shown to be MoO₂L₂ as established by IR data of organic extracts and the extracted species in the solid form. Extraction is almost quantitative at and above 10% LIX 622, and is found to be independent of [Mo(VI)] in the range of 10^–4 to 10^–3 M. The diluents CCl₄, CHCl₃ and C₆H₆ are found to be superior to solvents of high dielectric constant for extraction of Mo(VI). Extraction of uranium(VI) by 10% (v/v) LIX 622 in benzene was found to increase with increasing equilibrium pH (3.0 to 6.0), and becomes quantitative at pH 5.9. Tributyl phosphate acts as a modifier up to 2% (v/v). Thorium(IV) is almost not extracted by LIX 622 or its mixture. Separation of Mo(VI) and U(VI) is feasible.     

A note on absorption and desorption of uranium by polyurethane foam

The separation of uranium/VI/ from solution using tri-n-octylphosphine-oxide /TOPO/ and polyurethane foam has been shown to be efficient and specific. A desorption method has been investigatied which recovers uranium and TOPO in independent fractions.     

Separation and Extraction of Uranium from Leach Liquor Containing Uranium and Molybdenum by Solvent Extraction with LIX 622N

The leach liquor (0.5 g/L Mo, 0.05 g/L U) obtained from the leaching process of molybdenum-uranium ore material was treated using solvent extraction to recover U(VI) by LIX 622N, which is a salicylaldoxime derivative. The influence of various basic variables such as pH, concentration of LIX 622N, temperature, different stripping reagents, phase ratio, and diluents was examined. Using 10% LIX 622N with the aqueous solution of equilibrium pH 6.0 and a phase ratio organic phase:aqueous phase (O:A) = 1:1, a two-stage McCabe-Thiele plot was constructed, which showed 99.9% of U extraction with no co-extraction of molybdenum. This was confirmed by a 6-cycle counter current simulation (CCS) study. The obtained data of temperature on the extraction of uranium showed that the extraction process is exothermic with enthalpy change of ?20.949 kJ mol^?1. The stripping of U(VI) was quantitative using 4 M H₂SO₄. The stable complex UO₂(HSO₄)R_org formed during extraction, which supports the cation exchange mechanism, and was confirmed by FTIR spectral analysis.      

Kinetics of Ge(IV) Extraction Using a Microstructured Membrane Contactor

For hydrometallurgical metal extraction, the mass transfer by diffusion is additionally coupled with a chemical reaction of the metal ion with the extractant molecule, usually at the interface. Consequently, the kinetics is either limited by diffusion or chemical reaction (or both, respectively, in a mixed regime). Conventional methods for determining the extraction kinetics often lead to a misinterpretation, especially for fast reactions, and an isolated view of the interfacial reaction is restricted. With a new microcontactor setup, it is possible to perform a comprehensive kinetic analysis with very low sample volumes compared to established methods. Additionally, it is possible to quantify all individual mass transfer resistances and identify the extraction regime with the developed mass transfer model. The chemical reaction part is investigated isolated, to derive rate laws and kinetic constants. The methodology is discussed for the extraction of Ge(IV) from aqueous solutions with the two extractants 5,8‐diethyl‐7‐hydroxydodecan‐6‐oxime (LIX 63) and 7‐(4‐ethyl‐1‐methyloctyl)‐8‐hydroxyquinoline (Kelex 100). It was found that the extraction with LIX 63 is reaction limited and with Kelex 100 the reaction resistance is in the same order of magnitude as the diffusion resistances. The obtained results provide fundamental kinetic data for the design of solvent extraction equipment.     

Two-stage extraction preconcentration and HPLC determination of phenol and 1-naphthol in aqueous solutions

The extraction of phenol and 1-naphthol with isomolar mixtures of ethyl acetate and hexane under batch conditions and with tributyl phosphate impregnated into a polyurethane foam under batch and dynamic conditions was studied. A procedure for determining phenol and 1-naphthol in aqueous samples was developed including their dynamic recovery on a column packed with polyurethane foam impregnated with tributyl phosphate, elution with a 0.1 M NaCl solution of pH 12.5–13.0, extraction with a mixture of ethyl acetate and hexane, and separation by normal-phase high-performance liquid chromatography (HPLC) with UV-detection. The overall preconcentration coefficient was 250. The detection limits were 2.5 μg/L. The relative error of determination was lower than 18%. The time of one determination was 2–2.5 h.     

Reversed Phase Extraction Chromatographic Separation Of Scandium With Amberlite LA-1 From Malonate Solutions

Abstract

Scandium was extracted at pH 5.0 from 0.01 M malonic acid on silica gel column impregnated with Amberlite LA-1. Nickel, zinc, cadmium, mercury, lead, tin, aluminium, and lanthanum in binary mixtures because they could not form malonato complexes. It was separated by the process of selective elution from elements such as zirconium, thorium, uranium, iron(III), gallium, indium, cerium(III), litanium by exploiting difference in stability of malonato complexes. Scandium was separated from multicomponent mixture containing yttrium, titanium, zironium, thorium, uranium and aluminium by a process of selective sorbtion and selective elution.     

Development and validation of HPLC‐MS/MS method for the determination of lixivaptan in mouse plasma and its application in a pharmacokinetic study

The aim of the present study was to develop a simple, sensitive and accurate liquid chromatography–electrospray ionization tandem mass spectrometry (ESI‐MS/MS) method for the determination of lixivaptan (LIX) in mouse plasma using vildagliptin as the internal standard (IS). A precipitation procedure was used for the extraction of LIX and vildagliptin from mouse plasma. Chromatographic separation of LIX was achieved using a C₁₈ analytical column (50 × 2.1 mm, 1.8 μm) at 25°C. The mobile phase comprised acetonitrile and ammonium formate (10 mm , pH 3.1; 40:60, v /v) pumped at a flow rate of 0.3 mL min⁻¹. A tandem mass spectrometer with an electrospray ionization source was used to perform the assay. Quantification of LIX at m/z 290 → 137 and IS at 154 → 97 was attained through multiple reaction monitoring. The investigated method was authenticated following the bio‐analytical method of validation guidelines of the US Food and Drug Administration. The developed method showed a good linearity over the concentration range from 5 to 500 ng mL⁻¹, and the calibration curve was linear (r = 0.9998). The mean recovery of LIX from mouse plasma was 99.2 ± 0.68%. All validation parameters for LIX were within the levels required for acceptance. The proposed method was effectively used for a pharmacokinetic study of LIX in mouse plasma.     

The role of the solvent in equilibrium and kinetic aspects of metal chelate extractions

Equilibria and kinetics for the extraction of nickel(II) and copper(II) by 2-hydroxy-5-nonylbenzophenone oxime (LIX 65N) in seven organic solvent systems were studied in order to test the validity of several hypotheses related to the role of the solvent in equilibrium and kinetic aspects of metal chelate extraction. For the nickel—LIX 65N system, the extraction constant is essentially independent of the solvent system, whereas for the copper—LIX 65N system, the extraction constant is not independent of solvent; this indicates that while the stoichiometry of the nickel chelate remains the same in all solvents, that of copper does not. The observed rate constant for the nickel—LIX 65N extraction was found to vary inversely with the LIX 65N distribution constant as predicted from a mechanism involving slow formation of the 1:1 complex. The observed reaction rate constant for the copper—LIX 65N varied inversely with the square of the distribution constant, also in accordance with the previously postulated mechanism of the slow formation of the 2:1 copper complex. This study, therefore, unequivocally eliminates the interfacial mechanism in favor of the homogeneous chemical reaction mechanism for the extraction of metal ions by LIX 65N, as well as by other similar high-molecular-weight extractants.     

Extraction of certain actinide and lanthanide elements from different acid media by polyurethane foams loaded with di(2-ethylhexyl)phosphoric acid (HDEHP)

The extraction of uranium(VI) from an aqueous HNO₃ phase into an organic phase consisting of a polyurethane foam immobilizing a solution of di(2-ethylhexyl)phosphoric acid (HDEHP) in o-dichlorobenzene has been investigated at varying concentrations of nitric acid and HDEHP. The mechanism of the extraction is discussed on the basis of the results obtained. The aggregation number of HDEHP immobilized on the foam was obtained from the analysis of data obtained for the extraction of cerium(III) from acidic perchlorate solutions of constant ionic strength.