Solid Phase Extraction Of Uranium Research Articles

Highly efficient solid phase extraction of uranium with TOPO-menthol based eutectic solvent as stationary phase from acidic feed relevant to front-end applications

Novel methods of separation and purification are envisaged for natural uranium, containing 0.7% of fissile 235U, a precious resource that fuels nuclear power plants. The present study demonstrates Solid phase extraction (SPE) of uranium as a sustainable alternative to conventional liquid-liquid extraction, leading to minimisation of organic inventory and enhancement of ease of operation concerning usage of viscous eutectic solvent. Overcoming the issue of the low solubility of organophosphorus extractant tri-octyl phosphine oxide (TOPO) in a hydrocarbon diluent, the aqueous insoluble, non-ionic eutectic solvent could be prepared with biodegradable menthol having TOPO: menthol mole ratio of 1:2 (MT2), 1:3 (MT3) and 1:4 (MT4). Eutectic solvents were sorbed on radio chemically stable Chromosorb W resin as solid support (MTC2, MTC3, MTC4), with loading of 45% for MTC2 and 40% for both MTC3 and MTC4, confirmed by weight difference and thermogravimetry. Batch sorption studies of U(VI) from nitric acid medium revealed attainment of equilibrium at 60 min., following a pseudo-second-order rate equation, Langmuir adsorption isotherm and a static capacity of 19 mg g−1. The U(VI) uptake was found to increase with the increase in acid molarity indicating solvating mechanism of extraction (KD = 1240 ± 4, 4 M HNO3). Recyclability was established and stripping was effective with 0.5 M HNO3. Column operation was also successfully demonstrated (breakthrough capacity = 18.9 mg g−1). The U(VI) uptake of >98% was indicated for nitric acid-digested crude yellow cake matrices viz. sodium diuranate (SDU), magnesium diuranate (MDU) and heat-treated uranium peroxide (HTUP). For higher matrix content, near complete uranium uptake and suppression of extraction of representative impurities (Fe, Mn, Ni, Ce) was revealed indicating facile uranium separation and purification from matrices relevant to the front end of the nuclear fuel cycle.

Synthesis, characterization and application of a zirconium-based MOF-808 functionalized with isonicotinic acid for fast and efficient solid phase extraction of uranium(VI) from wastewater prior to its spectrophotometric determination

BackgroundA zirconium-based metal-organic framework (Zr-MOF), named MOF-808, was synthesized and fully characterized by solvo-thermal method and functionalized by isonicotinic acid and employed as an efficient adsorbent for selective extraction and preconcentration of uranyl ions from water and waste water samples in a batch solid phase extraction.ResultsParameters affecting extraction such as volume and pH of the sample solution, the amount of sorbent, type and volume of eluting solvent, and adsorption and desorption times were investigated and optimized. Under the optimized conditions, high extraction efficiency was observed with a limit of detection of 0.9 µg L− 1 for uranyl ions and relative standard deviations were found to be better than 2.1% in the range of 0.07–1000 µg L− 1.ConclusionsThese results indicated that the above procedure is fast, inexpensive, effective, reliable, applicable and organic solvent-free and showed the highly performance and stability of the Zr-MOF in SPE based analytical techniques.

Cu2O-CuO ball like/multiwalled carbon nanotube hybrid for fast and effective ultrasound-assisted solid phase extraction of uranium at ultra-trace level prior to ICP-MS detection

Multiwalled carbon nanotube/Cu2O-CuO ball like hybrid material (MWCNTs/Cu2O-CuO) synthesized using of a green hydrothermal process was evaluated as a new sorbent for solid phase extraction of uranium with inductively coupled plasma mass spectrometry (ICP-MS). According to our best knowledge, this new material was synthesized and used as solid phase extraction adsorbent for the first time in the literature. The characterization of new hybrid material was carried out using Raman spectroscopy, X-ray diffraction (XRD) and scanning electronic microscopy techniques (SEM, SEM-EDX and SEM-Mapping). The characterization results demonstrated that the new hybrid nanostructure was successfully obtained. The ultrasound-assisted solid phase extraction (UA-SPE) procedure was performed using 100 mg of new hybrid sorbent, 1000 μL of a 0.1% (w/v) solution of α-benzoin oxime and 2000 μL of phosphate buffer at pH 7.0 for separation and preconcentration of uranium. Uranium was eluted with 2 M HCl and the levels of uranium was measured by using ICP-MS. The linearity was observed between 2.5 and 100 ng mL−1 concentration range with a good correlation coefficient (r = 0.999, n = 7). The obtained limit of detection and quantitation values were 0.52 and 1.70 ng mL−1, respectively. Under optimum conditions, the preconcentration factor (PF) was calculated as 13.3. The accuracy of the developed method was assessed by analyzing of TMDA-62.2, TMDA-70.2 (Environment Canada) and GBW-07423 certified reference water and soil materials. The proposed UA-SPE-ICP-MS procedure developed with MWCNTs/Cu2O-CuO hybrid material was successfully applied to the analysis of uranium at ultra-traces levels in environmental water and geological rock samples.

Solid phase extraction of uranium from phosphoric acid: kinetic and thermodynamic study

Abstract There is a high interest to develop suitable solid phase extractants for uranium separation from aqueous solutions in order to reduce cost and enhance the efficiency. This paper describes solid phase extraction of uranium(VI) from aqueous phosphoric acid solution using MCM-41 based D2HEPA-TOPO organophosphorous extractants. The mixture of D2HEPA (di-2-ethyl-hexylphosphoric acid) and TOPO (tri-n-octylphosphine oxide) was impregnated into the pores of MCM-41 and the synthesized sorbent was fully characterized. The influences of different factors such as synergistic mixture ratio, phosphoric acid concentration, mixing time and temperature were investigated. The results showed that 90% of uranium(VI) extraction can be achieved within 5 min, using D2HEPA-TOPO@MCM-41 (mass ratio 2:1 w/w) from 1 M phosphoric acid containing 64 ppm of uranium at room temperature. High adsorption capacity of uranium(VI) have been achieved at the mentioned conditions. The rate constant for the chemical adsorption of uranium(VI) was 0.988 g mg‒1 min‒1 calculated by the pseudo-second order rate equation. The obtained thermodynamics parameters showed that uranium(VI) adsorption from H3PO4 is an exothermic and spontaneous process.

Resistance, bioaccumulation and solid phase extraction of uranium (VI) by Bacillus vallismortis and its UV–vis spectrophotometric determination

Bioaccumulation, resistance and preconcentration of uranium(VI) by thermotolerant Bacillus vallismortis were investigated in details. The minimum inhibition concentration of (MIC) value of U(VI) was found as 85 mg/L and 15 mg/L in liquid and solid medium, respectively. Furthermore, the effect of various U(VI) concentrations on the growth of bacteria and bioaccumulation on B. vallismortis was examined in the liquid culture media. The growth was not significantly affected in the presence of 1.0, 2.5 and 5.0 mg/L U(VI) up to 72 h. The highest bioaccumulation value at 1 mg/L U(VI) concentration was detected at the 72nd hour (10 mg/g metal/dry bacteria), while the maximum bioaccumulation value at 5 mg/L U(VI) concentration was determined at the 48th hour (50 mg metal/dry bacteria). In addition to these, various concentration of U(VI) on α-amylase production was studied. The α-amylase activities at 0, 1, 2.5 and 5 mg/L U(VI) were found as 3313.2, 3845.2, 3687.1 and 3060.8 U/mg, respectively at 48th. Besides, uranium (VI) ions were preconcentrated with immobilized B. vallismortis onto multiwalled carbon nanotube (MWCNT) and were determined by UV-vis spectrophotometry. The surface macro structure and functionalities of B. vallismortis immobilized onto multiwalled carbon nanotube with and without U(VI) were examined by FT-IR and SEM. The optimum pH and flow rate for the biosorption of U(VI) were 4.0–5.0 and 1.0 mL/min, respectively. The quantitative elution occurred with 5.0 mL of 1 mol/L HCl. The loading capacity of immobilized B. vallismortis was determined as 23.6 mg/g. The certified reference sample was employed for the validation of developed solid phase extraction method. The new validated method was applied to the determination of U(VI) in water samples from Van Lake-Turkey.

Solid phase extraction of uranium on a new brush type graft copolymer and spectrophotometric determination of its in water samples

A new versatile solid phase extraction and spectrophotometric determination of uranium (VI) was proposed with using poly(caprolactone-b-vinyl benzyl chloride-g-dimethyl amino ethyl methacrylate), poly(CL-b-VB-g-DMAEMA), amphiphilic brush type block/graft copolymer. The method is based on the adsorption of uranium(VI)-pyrocatechol violet complex on surface on the adsorbent. The parameters such as pH, amount of ligand and copolymer, sample volume were optimized. Detection limit, preconcentration factor and relative standard deviation were found as 0.45 µg L−1, 100 and 3.8 %, respectively. Adsorption capacity of the polymer for uranium(VI) was found 52 mg g−1. The method was applied to different water samples and standard reference materials.

Solid phase extraction of uranium (VI) from phosphoric acid medium using macroporous silica-based D2EHPA-TOPO impregnated polymeric adsorbent

This paper describes uranium extraction from aqueous phosphoric acid medium using a silica/polymer based D2EHPA-TOPO adsorbent. The mixture of di-2-ethyl-hexylphosphoric acid (D2EHPA) and tri-n-octylphosphine oxide (TOPO) was impregnated and immobilized into the pores of SiO2-P particles. The various experimental parameters such as the synergistic mixture ratio of extractants, phosphoric acid concentration, the contact time and the temperature were investigated. The results showed that 95% uranium extraction was achieved after 10min contacting time using D2EHPA-TOPO/SiO2-P (mass ratio=3:1 w/w) adsorbent from 1M phosphoric acid solution containing 165ppmU (VI), 5000ppm Fe (III), 1000ppm Ca (II) and 1000ppm Al(III) at 25°C. Also, the obtained results displayed the high adsorption capacity for Uranium as high as 48mgg−1 at the mentioned conditions. The rate constant (1.62gmg−1min−1) was calculated by the pseudo-second order equation and it shows that reaction rate was controlled by the chemical adsorption of uranium. Furthermore, D2EHPA-TOPO (3:1)/SiO2-P has a good selectivity for U(VI) among the co-existing elements (Fe, Al and Ca). The adsorption isotherms were well described by the Redlich–Peterson equation, closely followed by the Langmuir equation which confirms the mechanism is chemical monolayer adsorption. Obtained thermodynamic parameters (∆H°.∆S°and∆G°) reveal that the U(VI) adsorption to be an exothermic and spontaneous process.

Studies on sorption of uranium on chitin: a solid-state extractant application for removal of uranium from ground water

Studies were carried out to remove uranium from aqueous systems based on the solid phase extraction of uranium by powdered chitin. The effects of various parameters like pH, contact time, and amount of chitin for quantitative sorption of uranium on chitin have been studied. The sorption studies with spiked water samples and natural ground water samples showed that uranium was easily sorbed onto powdered chitin between pH 3 and 6. The effects of various cations and anions, which are present in the water samples, were studied. The method is simple, fast and environmental friendly and it is unaffected by the other ions present in the natural waters. The accuracy of the method was evaluated by applying the present method on ground water samples containing uranium in the range of 100–2,200 μg/L. The uranium remained in water samples is <20 μg/L after treatment with chitin, which is below the AERB limits given for uranium in drinking water. The values are an average of five replicate measurements, with an RSD of ±10 μg/L at 100 μg/L uranium in water samples.

Solid phase extraction of uranium and thorium on octadecyl bonded silica modified with Cyanex 302 from aqueous solutions

A simple and reliable method for rapid extraction and determination of uranium and thorium using octadecyl-bonded silica modified with Cyanex 302 is presented. Extraction efficiency and the influence of various parameters such as aqueous phase pH, flow rate of sample solution and amount of extractant has been investigated. The study showed that the extraction of uranium and thorium increase with increasing pH value and was found to be quantitative at pH 6; and the retention of ions was not affected significantly by the flow rate of sample solution. The extraction percent were found to be 89.55 and 86.27 % for uranium and thorium, respectively. The maximal capacity of the cartridges modified by 30 mg of Cyanex 302 was found to be 20 mg of uranium and thorium. The method was successfully applied to the extraction and determination of uranium and thorium in aqueous solutions. The percentage recovery of uranium and thorium in a number of natural as well as seawater samples of Iran were also investigated and found to be in the range of 85–95 %.

Geobacillus thermoleovorans immobilized on Amberlite XAD-4 resin as a biosorbent for solid phase extraction of uranium (VI) prior to its spectrophotometric determination

Geobacillus thermoleovorans subsp stromboliensis, was immobilized on an Amberlite XAD-4 ion exchanger and used as a solid phase extractant for the preconcentration of U(VI) ions prior to their determination by UV-VIS spectrophotometry. Parameters affecting the preconcentration (such as the pH value of the sample solution, the concentration of U(VI), the volume and type of eluent, the flow rate and the effect of potentially interfering ions) were studied. The optimum pH for the sorption of U(VI) was found to be pH 5.0. 5.0 mL of 1 M hydrochloric acid were used to eluate the U(VI) from the column. The loading capacity is 11 mg g−1. The limits of detection and quantification are 2.7 and 9.0 μg L−1, respectively, and relative standard deviations are <10 %. The method was applied to the determination of U(VI) in a certified reference sample (NCS ZC-73014; tea leaves) and in natural water samples.

Synthesis of surface imprinted nanospheres for selective removal of uranium from simulants of Sambhar salt lake and ground water

Imprinted polymer nanospheres for uranium were prepared by complexing uranyl ion on to quinoline-8-ol functionalized 3-aminopropyltrimethoxysilane modified silica nanoparticles followed by surface imprinting with 4-VP (4-vinyl pyridine), HEMA (2-hydroxy ethyl methacrylate) and EGDMA (ethylene glycol dimethacrylate) as the functional monomers and cross linking agent respectively with AIBN (2,2′-azo-bis-isobutyronitrile) as initiator and 2-methoxyethanol as the porogen. Non-imprinted polymer material was also prepared under similar conditions omitting uranyl ion. The above materials were used for solid phase extraction of uranium. Recent realization that its chemical toxicity is dominant than radiation hazards makes decontamination a relevant topic for environmental point of view, particularly in the light of projected global thrust for uranium fuel based atomic power plants. The material offers high retention capacity of 97.1 μmol g −1 for 10 mg L −1 of uranium that does not require tedious grinding and sieving steps, is water compatible and works in the pH range of 5–7, making it ideal for possible use in decontamination of polluted natural water samples or front end effluents of nuclear power reactors.

Solid Phase Extraction of Uranium by Naphthalene‐Methyltrioctylammonium Chloride and Arsenazo(III) Adsorbent and Subsequent Spectrophotometric Determination

AbstractA simple and effective method has been presented for the preconcentration of uranium by solid phase extraction. For this purpose arsenazo(III) supported on naphthalene‐methyltrioctylammonium chloride was used as an adsorbent and uranium solution at pH 3.5 with flow rate of 1 mL·min−1 was passed through the column. Therefore, uranium‐arsenazo(III) complex was formed onto column. Uranium was quantitatively eluted with 5 mL of a 0.1% ammonium tetraphenylborate and determined by spectrophotometric method at 652 nm. Several parameters such as pH, amount of reagents, sample volume, etc. were investigated. The effect of diverse ions on the preconcentration has also been studied and the optimized conditions developed have been utilized for the trace determination of uranium. A preconcentration factor of 100 was achieved. The relative standard deviation (N=8) was 0.5% for 3 ng· mL−1 of uranium. The three sigma detection limit (36) was 0.045 ng·mL−1

Solid phase extraction of uranium(VI) onto benzoylthiourea-anchored activated carbon

A new solid phase extractant selective for uranium(VI) based on benzoylthiourea anchored to activated carbon was developed via hydroxylation, amidation and reaction with benzoyl isothiocyanate in sequence. Fourier transform infrared spectroscopy and total element analysis proved that benzoylthiourea had been successfully grafted to the surface of the activated carbon, with a loading capacity of 1.2 mmol benzoylthiourea per gram of activated carbon. The parameters that affect the uranium(VI) sorption, such as contact time, solution pH, initial uranium(VI) concentration, adsorbent dose and temperature, have been investigated. Results have been analyzed by Langmuir and Freundlich isotherm; the former was more suitable to describe the sorption process. The maximum sorption capacity (82 mg/g) for uranium(VI) was obtained at experimental conditions. The rate constant for the uranium sorption by the as-synthesized extractant was 0.441 min −1 from the first order rate equation. Thermodynamic parameters (Δ H 0 = −46.2 kJ/mol; Δ S 0 = −98.0 J/mol K; Δ G 0 = −17.5 kJ/mol) showed the adsorption of an exothermic process and spontaneous nature, respectively. Additional studies indicated that the benzoylthiourea-anchored activated carbon (BT-AC) selectively sorbed uranyl ions in the presence of competing ions, Na +, Co 2+, Sr 2+, Cs + and La 3+.

Simultaneous extraction and preconcentration of uranium and thorium in aqueous samples by new modified mesoporous silica prior to inductively coupled plasma optical emission spectrometry determination

A new synthesized modified mesoporous silica (MCM-41) using 5-nitro-2-furaldehyde (fural) was applied as an effective sorbent for the solid phase extraction of uranium(VI) and thorium(IV) ions from aqueous solution for the measurement by inductively coupled plasma optical emission spectrometry (ICP OES). The influences of some analytical parameters on the quantitative recoveries of the analyte ions were investigated in batch method. Under optimal conditions, the analyte ions were sorbed by the sorbent at pH 5.5 and then eluted with 1.0 mL of 1.0 mol L −1 HNO 3. The preconcentration factor was 100 for a 100 mL sample volume. The limits of detection (LOD) obtained for uranium(VI) and thorium(IV) were 0.3 μg L −1. The maximum sorption capacity of the modified MCM-41 was found to be 47 and 49 mg g −1 for uranium(VI) and thorium(IV), respectively. The sorbent exhibited good stability, reusability, high adsorption capacity and fast rate of equilibrium for sorption/desorption of uranium and thorium ions. The applicability of the synthesized sorbent was examined using CRM and real water samples.