Vanadium In Seawater Research Articles

Highly Efficient Electrocatalytic Uranium Extraction from Seawater over an Amidoxime-Functionalized In-N-C Catalyst.

Seawater contains uranium at a concentration of ≈3.3 ppb, thus representing a rich and sustainable nuclear fuel source. Herein, an adsorption–electrocatalytic platform is developed for uranium extraction from seawater, comprising atomically dispersed indium anchored on hollow nitrogen‐doped carbon capsules functionalized with flexible amidoxime moieties (In–N x –C–R, where R denotes amidoxime groups). In–N x –C–R exhibits excellent uranyl capture properties, enabling a uranium removal rate of 6.35 mg g−1 in 24 h, representing one of the best uranium extractants reported to date. Importantly, In–N x –C–R demonstrates exceptional selectivity for uranium extraction relative to vanadium in seawater (8.75 times more selective for the former). X‐ray absorption spectroscopy (XAS) reveals that the amidoxime groups serve as uranyl chelating sites, thus allowing selective adsorption over other ions. XAS and in situ Raman results directly indicate that the absorbed uranyl can be electrocatalytically reduced to an unstable U(V) intermediate, then re‐oxidizes to U(VI) in the form of insoluble Na2O(UO3·H2O) x for collection, through reversible single electron transfer processes involving InN x sites. These results provide detailed mechanistic understanding of the uranium extraction process at a molecular level. This work provides a roadmap for the adsorption–electrocatalytic extraction of uranium from seawater, adding to the growing suite of technologies for harvesting valuable metals from the earth's oceans.

Dwindling vanadium in seawater during the early Cambrian, South China

Elemental vanadium (V), an essentially redox-sensitive metal in seawater, has had a significant impact on the understanding of the evolution of the atmosphere-ocean system throughout the history of the Earth. In fact, the geochemical cycle of V in early Cambrian seawater may have had an influence on the Chengjiang Biota in South China; however, it has not yet been well established. Given the authigenic vanadium accumulation is sensitive to the redox conditions of seawater, here, to constrain the geochemical cycle of V in seawater during the early Cambrian, the Mo, U and total organic carbon (TOC) distributions with high-resolution samples from both the outer shelf and slope facies (e.g., the Duoding and Longbizui sections), are applied to evaluate the redox conditions of ambient seawater. The Mo-U relationships indicate that the redox conditions of the mid-depth seawater evolved in a systematic way in South China, transitioning from an Fe-Mn reduction zone to anoxic/intermittently euxinic states and then to oxic conditions during the early Cambrian. As a consequence, the authigenic V enrichment, constrained by the marine redox conditions, was mainly controlled by the Fe-Mn particulate shuttle and the reduction and adsorption of organic matter in anoxic/euxinic conditions. However, the decoupling among V, Mo, U and TOC under anoxic/euxinic conditions suggests a dwindling vanadium concentration in the early Cambrian seawater of South China. The scavenging efficiency of V from seawater is much higher than those of Mo and U under anoxic/euxinic conditions. Ultimately, these trace elements (e.g., Mo, U, and especially V) in seawater could effectively be regulated and adjusted to a reasonable level under the widespread anoxic/euxinic conditions. The drawdown of trace elements in seawater might provide an early-stage preparation of the marine environment for the subsequent Chengjiang Biota.

First-Principles Integrated Adsorption Modeling for Selective Capture of Uranium from Seawater by Polyamidoxime Sorbent Materials.

Nuclear power is a relatively carbon-free energy source that has the capacity to be utilized today in an effort to stem the tides of global warming. The growing demand for nuclear energy, however, could put significant strain on our uranium ore resources, and the mining activities utilized to extract that ore can leave behind long-term environmental damage. A potential solution to enhance the supply of uranium fuel is to recover uranium from seawater using amidoximated adsorbent fibers. This technology has been studied for decades but is currently plagued by the material's relatively poor selectivity of uranium over its main competitor vanadium. In this work, we investigate the binding schemes between uranium, vanadium, and the amidoxime functional groups on the adsorbent surface. Using quantum chemical methods, binding strengths are approximated for a set of complexation reactions between uranium and vanadium with amidoxime functionalities. Those approximations are then coupled with a comprehensive aqueous adsorption model developed in this work to simulate the adsorption of uranium and vanadium under laboratory conditions. Experimental adsorption studies with uranium and vanadium over a wide pH range are performed, and the data collected are compared against simulation results to validate the model. It was found that coupling ab initio calculations with process level adsorption modeling provides accurate predictions of the adsorption capacity and selectivity of the sorbent materials. Furthermore, this work demonstrates that this multiscale modeling paradigm could be utilized to aid in the selection of superior ligands or ligand compositions for the selective capture of metal ions. Therefore, this first-principles integrated modeling approach opens the door to the in silico design of next-generation adsorbents with potentially superior efficiency and selectivity for uranium over vanadium in seawater.

Surface Ion-Imprinted Polypropylene Nonwoven Fabric for Potential Uranium Seawater Extraction with High Selectivity over Vanadium

Uranium seawater extraction is strategically important to guarantee the future supply for nuclear power generation. However, it is still a challenge to selectively capture uranium over vanadium in seawater. In this paper, we propose a new method for potential uranium seawater extraction with high selectivity over vanadium. Specifically, surface ion-imprinted polypropylene nonwoven fabric is prepared by copolymerization of 4-vinylbenzyl chloride and 1-vinylimidazole in the presence of uranyl tricarbonate complex. The sorption follows the pseudo-second-order model and can reach the equilibrium with a large capacity of 133.3 mg/g within 15 h at pH 8.0 and 298.15 K. The imprinted fabric shows excellent selectivity toward uranium over vanadium and the other coexisting ions in seawater. In addition, it exhibits good salt-resistant stability and can be regenerated efficiently after five cycles. This work indicates that the imprinted fabric may be a promising sorbent for potential uranium seawater extraction.

Flow-Injection Determination of Vanadium in Seawater Samples with Acidic Potassium Permanganate Chemiluminescence

Chemiluminescence from the vanadium and potassium permanganate reaction was studied under acidic conditions to develop a sensitive method for vanadium determination using the formaldehyde enhancement effect. The method was successfully applied to the determination of vanadium in seawater. Experimental parameters were optimized, including acid concentration, potassium permanganate and formaldehyde concentration. A linear calibration graph was obtained in the concentration range of 2.0 x 10(-9)-5 x 10(-6) M with relative standard deviations (n = 4) in the range of 1.8-3.1%. The detection limit (3sigma blank) was 8.0 x 10(-10) mol L(-1) with a sample throughput of 100 h(-1). The effect of salinity and various interfering cations and anions were studied. The method was applied to determine total dissolved vanadium in seawater samples and certified reference materials after online reduction with amalgamated zinc column.

Localization of Vanabins, Vanadium-Binding Proteins, in the Blood Cells of the Vanadium-Rich Ascidian, Ascidia sydneiensis samea

Some species of the family Ascidiidae accumulate vanadium in concentrations in excess of 350 mM, which is about 10 (7)-fold higher than the concentration of vanadium in seawater. In these species, signet ring cells with a single large vacuole in which vanadium ions are contained function as vanadium-accumulating cells. These have been termed vanadocytes. We recently isolated five vanadium-binding proteins, which we named Vanabin1, Vanabin2, Vanabin3, Vanabin4, and VanabinP, from vanadocytes of the vanadium-rich ascidian Ascidia sydneiensis samea. In this study, we analyzed localization of the Vanabins in the blood cells of A. sydneiensis samea using monoclonal antibodies and confocal microscopy. The Vanabin1 and Vanabin2 proteins were found in the cytoplasm and/or in some organelles of vanadocytes. Vanabin3 was also detected in the cytoplasm, while Vanabin4 was found exclusively in the cytoplasmic membrane.

Current status of adsorbent for metal ions with radiation grafting and crosslinking techniques

Removal of toxic metals from streaming water and ground water is important task to preserve environment. Radiation processing of grafting and crosslinking can synthesis adsorbent having high performances. Graft adsorbent can be synthesized by using the conventional polymer like polyethylene having variety shapes such as membrane, cloth, and fiber. Especially, the obtained fibrous adsorbent has 100 times higher rate of adsorption than that of commercialized resin. Fibrous adsorbent of iminodiacetate was applied to the removal of cadmium from the scallop waste. Furthermore, the amidoxime adsorbent is useful for recovery of rare metals such as uranium and vanadium in seawater. Novel fibrous adsorption for arsenic was synthesized by direct grafting of phosphoric monomer and following zirconium-loading. Crosslinked natural polymers like carboxymethyl chitin–chitosan in the paste-like state are applicable for the metal adsorbent. This adsorbent can be biodegraded after usage.

Determination of trace levels of dissolved vanadium in seawater by use of synthetic complexing agents and inductively coupled plasma-atomic emission spectroscopy (ICP-AES).

In the determination of traces of dissolved vanadium in complex matrices such as seawater, separation and enrichment from the matrix is of special importance. A wide variety of methods has been proposed for preconcentration, depending to the nature of samples and the methods to be used for measurement. Among these methods separation techniques based on sorption on to chelating resins seem convenient, rapid, and capable of achieving a high concentration factor. The methods proposed in this paper are based on the transformation of all dissolved vanadium species in seawater into organic complexes by use of synthetic complexing agents such as dithizone, luminol, or 8-hydroxyquinoline; the resulting vanadium-organic complexes were sorbed on to a C(18) column at a flow rate of 5 mL min(-1). The vanadium sorbed on the C(18) columns was then stripped by use of nitric acid (2 mol L(-1)) and analysed by inductively coupled plasma-atomic emission spectroscopy, ICP-AES. This method was optimised and use of other chelating resins, such as chelamine, chelex-100, and immobilised 8-hydroxyquinoline and was compared by passing seawater samples directly over the resins. The experimental conditions (pH, acid used for elution, and contact time between the liquid sample and the resin) were optimised. The results were compared for all the resins used and were indicative of excellent and coherent reproducibility.

Direct determination of trace elements in sea-water using reaction cell inductively coupled plasma mass spectrometry

A method is described for the direct determination of several transition elements in sea-water by reaction cell (RC)-inductively coupled plasma mass spectrometry (ICP-MS) using ammonia as a reaction gas. Results show significant improvement over standard quadrupole (Q) ICP-MS performance for direct sea-water analysis and were comparable to high resolution (HR) ICP-MS. In this study, the RC-ICP-MS was used to determine chromium, copper, manganese, nickel and vanadium in sea-water. Ammonia gas was passed through the reaction cell to reduce molecular ion interference. These interferences normally lead to false positive results when low resolution quadrupole ICP-MS (Q-ICP-MS) is used to analyze sea-water. Good recoveries were obtained for V-51, Cr-52 and Mn-55 in the 1∶10 diluted sea-water, CASS-4, NASS-4 and SLEW-3. Molecular ion interference was reduced significantly but not completely for Ni-58 and Cu-63, giving rise to a positive bias typically no more than 0.3 µg l−1. A matrix blank subtraction or matrix matched external calibration can be used to further improve the accuracy for these elements at levels below 0.5 µg l−1. Detection limits in the undiluted sea-water range from 0.02 µg l−1 for chromium to 0.3 µg l−1 for copper. The precision and accuracy of the method were checked against three certified reference standards.

Simultaneous determination of trace amounts of copper, nickel and vanadium in sea-water by high-performance liquid chromatography after extraction and back-extraction

A method for the simultaneous determination of Cu, Ni and V in sea-water by HPLC is described. The complexes of these metals with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)-phenol (5-Br-PAPS) are extracted with capriquat (trioctylmethylammonium chloride) in xylene and back-extracted into sodium perchlorate solution followed by separation and determination by HPLC with an octadecylsilane column and spectrophotometric detection. The conditions of extraction and back-extraction such as, pH, concentration of 5-Br-PAPS or capriquat and concentration of sodium perchlorate are investigated. Linear calibration curve ranges, limits of detection and interferences owing to other ions in sea-water are presented. Application of this method to the trace analysis of Cu, Ni and V in sea-water is demonstrated.

Determination of vanadium in sea water by catalytic adsorptive cathodic stripping voltammetry

The sensitivity of adsorptive cathodic stripping voltammetry (CSV) to vanadium is much improved by inclusion of a catalytic effect. The deposition step is based on the adsorptive accumulation of complex species with catechol on a hanging mercury drop electrode. The reduction current of the adsorbed complex is catalytically enhanced by addition of bromate. This effect is utilised to develop a sensitive method to determine vanadium in natural waters including sea water. Optimum response was obtained at pH 6.6 in the presence of 20 mM bromate and 0.1 mM catechol; the deposition potential was −0.1 V and the square-wave modulation (50 Hz) was used. The limit of detection was 0.07 nM vanadium using a deposition time of 120 s and 0.6 nM at a deposition time of 15 s.

Determination of Molybdenum and Vanadium in Seawater by Ion-Exchange Preconcentration-Inductively Coupled Plasma Atomic Emission Spectrometry

A simple and rapid method has been developed for the determination of molybdenum and vanadium in seawater using ion-exchange preconcentration and inductively coupled plasma atomic emission spectrometry (ICP-AES). One hundred milliliters of seawater prepared as 0.05 M hydrochloric acid solution is passed through a cellulose phosphate column, and molybdenum and vanadium adsorbed on the cellulose are eluted simultaneously with dilute ammonia solution. The effluent collected is evaporated to a small volume, in which molybdenum and vanadium can be determined by ICP-AES. The overall recoveries of molybdenum and vanadium are 93.6 and 80.4%, respectively, at the level of 1 μgMo/100 ml and 0.1 μgV/100 ml. The proposed method has been successfully applied to the determination of the two elements in several seawater samples. Relative standard deviations (n = 3) are 2.0-2.9 and 0.3-4.3% for molybdenum and vanadium, respectively.

Ocean anoxia and the concentrations of molybdenum and vanadium in seawater

Molybdenum and vanadium are relatively unreactive in seawater and are preferentially concentrated in sediments overlain by anoxic or near-anoxic waters. We investigate the geochemistry of these metals by interpreting measurements from anoxic basins and sediment porewaters. The concentrations of Mo and V in the water column of anoxic basins are usually lower than in oxic seawater because of uptake into highly anoxic sediments. The mechanism of removal from solution appears to be diffusion across the sediment-water interface and immobilization within the sediments. Measurements from open ocean porewaters imply fluxes of vanadium from sediments that are greater than 10 times the dissolved and particulate river inflow, which is inconsistent with the distribution of vanadium in deep waters of the ocean and previous geochemical studies; this inconsistency shows that early diagenesis of this element is poorly understood. We estimate that the area of ocean sediment at present overlain by anoxic and near-anoxic water is accumulating 25 ± 15% and 8 ± 5% of the river influx of Mo and V, respectively. This fraction is 17 ± 10% for uranium, which has been shown to share some of the redox behavior of Mo and V. A case is made that changes in the concentrations of these elements in the ocean should be sensitive indicators of the portion of the ocean bottom overlain by anoxic seawater through geologic time.

Distribution of Ni, V, and petroleum hydrocarbons in recent sediments from the veracruz coast, Mexico

The coastline of Veracruz is a unique environment due to the presence of extensive coraline systems and of natural oil seeps. Depending on the environmental parameters the coraline system are highly productive and diverse. Changes in these parameters by non-natural processes will cause damage or even the disappearance of these systems. Thus baseline studies in the zone are important in order to establish the natural concentrations of trace metals and the presence of petroleum hydrocarbons originated either from natural oil seeps or accidental spills. In the present paper the concentrations of nickel and vanadium in seawater and in sediments, as well as petroleum hydrocarbons in sediments are described in order to obtain base line information for the assessment of future man-induced alterations of the study area.

Determination of vanadium in seawater by inductively coupled plasma atomic emission spectrometry using chelating resin column preconcentration

Determination of vanadium in seawater by inductively coupled plasma atomic emission spectrometry using chelating resin column preconcentration

Concentration and Separation of Molybdenum and Vanadium in Seawater by Flotation/Ion-Exchange

Concentration and Separation of Molybdenum and Vanadium in Seawater by Flotation/Ion-Exchange

Determination of molybdenum and vanadium in seawater by carbon furnace atomic absorption spectrometry with metal chelate coprecipitation.

金属キレート錯体を用いるモリブデン,バナジウムの共沈法を,特に海水試料の分析のために検討した.調べた金属イオンとキレート剤の組み合わせは,コパルト(II)-ピロリジンジチオカルバミン酸アンモニウム(APDC),銅(II)-APDC,クロム(VI)-APDC,コバルト(II)-ジエチルジチオカルバミン酸ナトリウム,アルミニウム(III)-8-キノリノール,銅(II)-クペロン,ニッケル(II)-ジメチルグリオキシムの7種である.共沈手順は,まず担体金属を添加,溶液のpHを調整した後有機キレート試薬を添加,沈殿を熟成させた後演過,沈殿物を1mol/lの硝酸5mlに溶解して炭素炉原子吸光法で定量する.コバルト(II)-APDCを用いる共沈法が最も高い回収率を示し,共沈時のpH3.5でモリブデン:94±3%,バナジウム:96±3%であった.本法での定量下限は,モリブデン:0.05μg/l,バナジウム:0.1μg/l,又海水における脱塩効果も十分であることを確認した.日本海溝9700mまでの海水中のモリブデン,バナジウムを本法を用いて定量した.

Determination of Vanadium in Sea Water by X-ray Fluorescent Spectrometry

Determination of Vanadium in Sea Water by X-ray Fluorescent Spectrometry

Direct electrochemical determination of dissolved vanadium in seawater by cathodic stripping voltammetry with the hanging mercury drop electrode

Polarographic measurements showed that Catechol complexes of vanadium(V) adsorb onto the hanging mercury drop electrode. This property forms the basis of a sensitive eiectrochemical technique by which dissolved vanadium in seawater can be determined directly. The reduction current of adsorbed complex ions of vanadium is measured by differential pulse cathodic stripping voltammetry, preceded by a period of collection of a few minutes. The peak potential Is at --0.7 V. Optimal experimental parameters were found to be a catechol concentration of 2 X IO-* M, a collection potential of -0.1 V, and a soiutlon pH of 6.9. The limit of detection is 0.3 nM vanadium after a 2-min collection with a stirred soiutlon, which is decreased further to 0.1 nM after a 15-min collection.

Determination of arsenic, molybdenum, uranium, and vanadium in seawater by by neutron activation analysis after preconcentration by colloid flotation

Colloid flotation of arsenic, molybdenum, uranium, and vanadium on hydrous iron(III) oxide permits rapid collection of the precipitate for neutron activation analysis. The precipitate is floated, in the presence of sodium dodecyl sulfate and tiny nitrogen bubbles, from 1 L of seawater at pH 5.7 +/- 0.2. Except for uranium, recoveries are better than 95%; about 75% of the uranium was recovered. Selenium(IV) and tungsten(VI) can be similarly collected but their natural concentration levels in seawater are below detection limits for 1 L volumes.