CN116607176A - Application of iron-based oxide in electrochemical seawater uranium extraction - Google Patents

Application of iron-based oxide in electrochemical seawater uranium extraction Download PDF

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CN116607176A
CN116607176A CN202310535706.7A CN202310535706A CN116607176A CN 116607176 A CN116607176 A CN 116607176A CN 202310535706 A CN202310535706 A CN 202310535706A CN 116607176 A CN116607176 A CN 116607176A
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seawater
uranium
electrochemical
iron
based oxide
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竹文坤
陈涛
何嵘
刘欢欢
张勇
孙囡
刘旺
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Southwest University of Science and Technology
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Abstract

The invention discloses an application of an iron-based oxide in electrochemical seawater uranium extraction, which comprises the following steps: adding an iron-based oxide, carbon black and a Nafion solution into absolute ethyl alcohol, adding the Nafion solution, performing ultrasonic treatment to obtain a mixed solution, uniformly coating the mixed solution on a carbon felt to obtain a sample of the carbon felt uniformly loaded with the iron-based oxide, and using the sample as a working electrode in a three-electrode system of an electrochemical workstation; the counter electrode in the three-electrode system is a platinum wire electrode, and the reference electrode is a silver/silver chloride electrode; filtering seawater by 0.2 μm filter, adding uranyl nitrate into seawater to obtain simulated uranium seawater, adding simulated uranium seawater into electrolytic cell of three-electrode system, and adopting-1.5V Vs AThe potential of g/AgCl extracts uranium from simulated uranium seawater. The invention adopts nanometer octahedron Fe 3 O 4 Electrochemical seawater uranium extraction is carried out, and nanometer octahedral Fe is carried out under the potential of-1.5V 3 O 4 The efficiency of electrochemical reduction of uranium is higher than that of nanocubes, and the performance is more excellent.

Description

Application of iron-based oxide in electrochemical seawater uranium extraction
Technical Field
The invention belongs to the technical field of seawater uranium extraction, and particularly relates to application of an iron-based oxide in electrochemical seawater uranium extraction.
Background
With the continued development of nuclear industry activities, uranium resources on earth will be depleted in less than a century. The uranium content in the ocean is about 1000 times that of land uranium, which has led to interest in extracting uranium from seawater. Because the concentration of uranium in seawater is extremely low and complex interfering ions exist, the traditional adsorption method has lag in extraction kinetics of uranium in seawater and has limited extraction capacity. Electrochemical uranium extraction in seawater is an emerging strategy, and has rapid kinetics and remarkable capacity improvement under the guidance of an electric field. In this case, the catalyst involved in the electrochemical uranium extraction is a key parameter in regulating the extraction efficiency. In the prior art, various electrocatalysts for uranium extraction have been developed, including carbon materials, metal monoatoms, metal oxides, and the like. Despite significant progress in the research of novel catalytic materials, the structure-activity research of electrochemical uranium extraction is still immature, and the reasonable design of catalysts is limited.
In the electrochemical uranium extraction process from seawater, preparation and selection of electrode catalyst materials are one of the critical factors for extraction efficiency and extraction capacity. The microstructure of the electrode material often determines the macroscopic effect of the electrode material in application, which has higher requirements on the preparation and development of the material for electrochemical uranium extraction from seawater.
In the extraction of electrochemical uranium, UO 2 2+ The local structure of the binding active site directly influences the extraction efficiency. For example, amidoxime groups near the Fe-N-C monoatoms achieved an extraction capacity of 1.2mg/g from real seawater within 24h. Another example is that the prior art demonstrates MoS 2 The sulphur defects at the edges are effective active centres for uranium reduction. Crystal face control is used as an effective and powerful local structure manipulation method, and can conveniently adjust the atomic distance and the atomic coordination environment so as to influence UO 2 2 + Adsorption configuration and coordination number of (a). Taking into account UO 2 2+ With O 2- The strong bond between the metal oxide and the crystal face control of the metal oxide can be O control 2- The local structure of the active site provides an ideal platform. Therefore, understanding the structure-activity relationship of the oxide catalyst with the adjustable crystal face is of great significance in revealing the uranium extraction mechanism of the seawater.
Disclosure of Invention
It is an object of the present invention to address at least the above problems and/or disadvantages and to provide at least the advantages described below.
To achieve these objects and other advantages and in accordance with the purpose of the invention, there is provided a use of an iron-based oxide in electrochemical uranium extraction from seawater, including the steps of:
firstly, adding iron-based oxide and carbon black into absolute ethyl alcohol, then adding Nafion solution, carrying out ultrasonic treatment for 0.5-1.5 hours to obtain mixed solution, pasting a carbon felt on an electric plate at 50 ℃, uniformly coating the mixed solution on the carbon felt, continuously coating after the absolute ethyl alcohol volatilizes, and coating until the mixed solution is exhausted to obtain a sample of the carbon felt uniformly loaded with the iron-based oxide, wherein the sample is used as a working electrode in a three-electrode system of an electrochemical workstation; the counter electrode in the three-electrode system is a platinum wire electrode, and the reference electrode is a silver/silver chloride electrode;
filtering the seawater through a 0.2 mu m filter, adding uranyl nitrate into the seawater to obtain simulated uranium seawater, adding the simulated uranium seawater into an electrolytic cell of a three-electrode system, and extracting uranium from the simulated uranium seawater by adopting the potential of-1.5V Vs Ag/AgCl.
Preferably, the iron-based oxide is nano octahedral Fe 3 O 4 And the nano octahedral Fe 3 O 4 Nano Fe in octahedral shape for transmission electron microscope pattern 3 O 4 Crystalline, and nano Fe 3 O 4 The crystal has a {222} crystal plane.
Preferably, in the first step, nano octahedral Fe 3 O 4 The preparation method of (2) comprises the following steps: adding ferric trichloride hexahydrate and sodium hydroxide into ethylene glycol, stirring for 0.5-1.5 hours, and ending stirring when the solution is changed from transparent clear to yellow transparent to obtain a mixture; transferring the mixture into a high-pressure reaction kettle, placing the mixture into an oven for hydrothermal reaction, reacting for 8-15 hours at 180-220 ℃, naturally cooling to room temperature, centrifuging by a centrifuge, washing by using deionized water and absolute ethyl alcohol, and drying to obtain nano octahedral Fe 3 O 4 。
Preferably, the mole ratio of the ferric trichloride hexahydrate to the sodium hydroxide is 1:3-7; the mol volume ratio of the ferric trichloride hexahydrate to the ethylene glycol is 1 mmol:8-12 mL.
Preferably, the mass ratio of the iron-based oxide to the carbon black is 4-6:3; the mass volume ratio of the iron-based oxide to the absolute ethyl alcohol is 4-6 mg: 1-3 mL; the mass volume ratio of the iron-based oxide to the Nafion solution is 4-6 mg:30-40 mu L; the concentration of the Nafion solution was 0.5wt%.
Preferably, the carbon felt is cut high: the width is 1cm: a 2cm quadrilateral shape was used.
Preferably, the concentration of uranyl nitrate in the simulated uranium seawater is 0.1-100 mg/L.
The invention at least comprises the following beneficial effects: the invention adopts nanometer octahedron Fe 3 O 4 Electrochemical seawater uranium extraction is carried out, and nanometer octahedral Fe is carried out under the potential of-1.5V 3 O 4 The efficiency of electrochemical reduction of uranium is higher than that of nanocubes, and the performance is more excellent. In 8mg/L uranium standard solution, nano octahedral Fe 3 O 4 The efficiency of extracting uranium by electrochemistry reaches 91 percent, and the nano cubic Fe with the exposed crystal face of {200}, is obtained 3 O 4 Performance is more than performanceExcellent. In 8mg/L uranium doped seawater, performing electrochemical extraction for eight hours to obtain nanometer octahedral Fe 3 O 4 The extraction efficiency of (2) can reach 91 percent, and is nano cubic Fe 3 O 4 Is 1.45 times as high as the extraction efficiency. And the uranium is extracted from 10L of natural seawater by electrochemical seawater, and the extraction amount of the uranium reaches 17.49 mug. The results show that the structure of the nano catalyst is closely related to the uranium extraction efficiency, and the efficiency of electrochemical seawater uranium extraction can be effectively improved by regulating and controlling crystal faces, so that the thought is provided for reasonable design and development of electrochemical seawater uranium extraction catalysis.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Description of the drawings:
FIG. 1 (a) nanooctahedral Fe 3 O 4 A TEM profile of (a); (b) Nanocubes of Fe 3 O 4 A TEM profile of (a); (c) Nano octahedral Fe 3 O 4 HRTEM patterns of (a); (d) Nanocubes of Fe 3 O 4 HRTEM patterns of (a);
FIG. 2 (a) nanooctahedral Fe 3 O 4 And nanocubes of Fe 3 O 4 An XRD pattern of (a); (b) Nano octahedral Fe 3 O 4 And nanocubes of Fe 3 O 4 XPS spectrum of (b);
FIG. 3 (a) nanooctahedral Fe 3 O 4 Na at 0.5M at a voltage of-1.5 VvsAg/AgCl 2 SO 4 A graph of current change with 20000 seconds in 8mg/L uranium solution; (b) Nano octahedral Fe 3 O 4 And nano-cubic Fe 3 O 4 At 8mg/L uranium solution and 0.5M Na 2 SO 4 Time-efficiency curve of (a);
FIG. 4 (a) nanooctahedral Fe 3 O 4 At 0.5M Na with single interfering ion 2 SO 4 Electrochemical extraction efficiency with 8mg/L uranium solution; (b) Nano octahedral Fe 3 O 4 Na at 0.5M 2 SO 4 Desorption efficiency versus time curve in solution; (c) Nanometer scaleOctahedral Fe 3 O 4 Na at 0.5M 2 SO 4 The extraction efficiency of four times of electrochemical extraction and desorption is changed with 8mg/L uranium solution;
FIG. 5 (a) nanooctahedral Fe 3 O 4 And nano-cubic Fe 3 O 4 Time-efficiency curve in 8mg/L uranium solution configured with seawater; (b) Nano octahedral Fe 3 O 4 Electrochemical extraction efficiency of competitive ions and uranium in 8mg/L uranium solution prepared from seawater;
FIG. 6 is a nano octahedral Fe 3 O 4 Desorbing to 20mL of 0.5M Na after 8 hours of electrochemical extraction in different volumes of real seawater 2 SO 4 Concentration with uranium obtained in 0.1M HCL;
FIG. 7 (a) nanooctahedral Fe 3 O 4 XRD patterns after 8 hours of electrochemical extraction; (b) Fe (Fe) 3 O 4 XPS total spectrum after 8 hours of electrochemical extraction; (c) Nano octahedral Fe 3 O 4 U4 fXPS profile after 8 hours of electrochemical extraction;
FIG. 8 is a nano octahedral Fe 3 O 4 And nano-cubic Fe 3 O 4 Reduction potential contrast for uranium.
The specific embodiment is as follows:
the present invention is described in further detail below with reference to the drawings to enable those skilled in the art to practice the invention by referring to the description.
It will be understood that terms, such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.
Example 1:
the application of the iron-based oxide in electrochemical seawater uranium extraction is characterized by comprising the following steps of:
step one, 5mg of nano octahedral Fe 3 O 4 3mg of carbon black was added to 2mL of absolute ethanol, followed by addition of 35. Mu.L of LNafion solution (0.5 wt%) and sonication for 1 hour to give a mixed solution, and a carbon felt (1 cm:2cm (height: width)) was stuck to 50℃electricityUniformly brushing the mixed solution on a carbon felt on a hot plate, and continuously brushing after the absolute ethyl alcohol volatilizes until the mixed solution is exhausted to obtain a sample of the carbon felt uniformly loaded with the iron-based oxide, wherein the sample is used as a working electrode in a three-electrode system of an electrochemical workstation; the counter electrode in the three-electrode system is a platinum wire electrode, and the reference electrode is a silver/silver chloride electrode; the nanometer octahedral Fe 3 O 4 Nano Fe in octahedral shape for transmission electron microscope pattern 3 O 4 Crystalline, and nano Fe 3 O 4 The crystal has a {222} crystal plane;
filtering the seawater through a 0.2 mu m filter, adding uranyl nitrate into the seawater to obtain simulated uranium seawater, adding the simulated uranium seawater into an electrolytic cell of a three-electrode system, and extracting uranium from the simulated uranium seawater by adopting the potential of-1.5V Vs Ag/AgCl;
the nanometer octahedral Fe 3 O 4 The preparation method of (2) comprises the following steps: 4mmol of ferric trichloride hexahydrate and 20mmol of sodium hydroxide were weighed, the above-mentioned drug was subjected to dissolution treatment with 40mL of ethylene glycol, and then the solution was stirred using magnetic stirring for 1 hour, and the stirring was ended when the solution turned from transparent to yellow transparent. Transferring the mixture to a high-pressure reaction kettle, placing the high-pressure reaction kettle in an oven for hydrothermal reaction, and reacting for 10 hours at 200 ℃; when the autoclave is naturally cooled to room temperature, centrifuging the synthesized product by a high-speed centrifuge, and washing by deionized water and absolute ethyl alcohol to remove organic and inorganic impurities; finally, the product is put into a drying oven to be dried, thus obtaining the nano octahedral Fe 3 O 4 ；
Example 2:
the application of the iron-based oxide in electrochemical seawater uranium extraction is characterized by comprising the following steps of:
step one, 5mg of nano octahedral Fe 3 O 4 Adding 3mg of carbon black into 2mL of absolute ethyl alcohol, adding 35 mu LNafion solution (0.5 wt%) and carrying out ultrasonic treatment for 1 hour to obtain a mixed solution, pasting a carbon felt (1 cm:2cm (height: width)) on an electric heating plate at 50 ℃, uniformly coating the mixed solution on the carbon felt,after the absolute ethyl alcohol volatilizes, continuing to brush until the mixed solution is exhausted, so as to obtain a sample of the carbon felt uniformly loaded with the iron-based oxide; the nanometer octahedral Fe 3 O 4 Nano Fe in octahedral shape for transmission electron microscope pattern 3 O 4 Crystalline, and nano Fe 3 O 4 The crystal has a {222} crystal plane;
step two, using the sample in the step one as a cathode in a double-electrode system; pt wire electrode was used as the counter electrode;
filtering natural seawater by a 0.2 mu m filter, then adding the filtered natural seawater into an electrolytic cell, limiting the tested current to-70 mA by adopting a constant current method, and continuously extracting uranium from the electrochemical seawater for 8 hours;
the nanometer octahedral Fe 3 O 4 The preparation method of (2) comprises the following steps: 4mmol of ferric trichloride hexahydrate and 20mmol of sodium hydroxide were weighed, the above-mentioned drug was subjected to dissolution treatment with 40mL of ethylene glycol, and then the solution was stirred using magnetic stirring for 1 hour, and the stirring was ended when the solution turned from transparent to yellow transparent. Transferring the mixture to a high-pressure reaction kettle, placing the high-pressure reaction kettle in an oven for hydrothermal reaction, and reacting for 10 hours at 200 ℃; when the autoclave is naturally cooled to room temperature, centrifuging the synthesized product by a high-speed centrifuge, and washing by deionized water and absolute ethyl alcohol to remove organic and inorganic impurities; finally, the product is put into a drying oven to be dried, thus obtaining the nano octahedral Fe 3 O 4 ；
Comparative example 1:
step one, 5mg of nanocube Fe 3 O 4 Adding 3mg of carbon black into 2mL of absolute ethyl alcohol, adding 35 mu LNafion solution (0.5 wt%) and carrying out ultrasonic treatment for 1 hour to obtain a mixed solution, pasting a carbon felt (1 cm:2cm (height: width)) on an electric heating plate at 50 ℃, uniformly coating the mixed solution on the carbon felt, continuing coating after the absolute ethyl alcohol volatilizes, and coating until the mixed solution is exhausted, so as to obtain a sample of uniformly loading iron-based oxide on the carbon felt, wherein the sample is used as a working electrode in a three-electrode system of an electrochemical workstation; the counter electrode in the three-electrode system is a platinum wire electrode, and the reference electrode is a silver/silver chloride electrode; by a means ofNano-cubic Fe 3 O 4 Has a {200} crystal plane and a {220} crystal plane;
filtering the seawater through a 0.2 mu m filter, adding uranyl nitrate into the seawater to obtain simulated uranium seawater, adding the simulated uranium seawater into an electrolytic cell of a three-electrode system, and extracting uranium from the simulated uranium seawater by adopting the potential of-1.5V Vs Ag/AgCl.
The nanocubes Fe 3 O 4 The preparation method of (2) comprises the following steps: 0.7g FeSO 4 Dissolved in 80mL distilled water. The solution was stirred under an argon atmosphere using a mechanical stirrer. Then 10mL of 2M KNO was added to the above solution 3 And 10ml of 1M NaOH, stirred at constant temperature in an oil bath at 90℃for 2h; centrifuging to collect the final product and drying to obtain nano-cube Fe 3 O 4 。
For nano octahedral Fe prepared in example 1 3 O 4 And nanocube Fe prepared in comparative example 1 3 O 4 Performing a correlation performance test;
test solution configuration: the standard uranium solution is prepared by taking ultrapure water as a solution and uranyl nitrate hexahydrate as a solute according to a certain proportion; adding standard seawater, taking natural seawater as a solution, and taking uranyl nitrate hexahydrate as a solvent, and preparing according to a certain proportion; natural seawater is taken from south sea and filtered by a microporous filter membrane of 0.2 mu m before the test is carried out, so as to remove impurities in the water;
uranium solutions of 0mg/L, 1mg/L, 2mg/L, 3mg/L, 4mg/L, 5mg/L, 6mg/L, 7mg/L and 8mg/L were respectively prepared and passed through an ultraviolet spectrophotometer to draw a standard curve of the uranium solution of 8 ppm.
Nanometer Fe with octahedral transmission electron microscope pattern is prepared through a solvothermal synthesis method and a coprecipitation synthesis method respectively 3 O 4 Nano Fe with cubic crystal and transmission electron microscope pattern 3 O 4 And (5) a crystal. As shown in fig. 1 (a) and 1 (b), nano octahedral Fe 3 O 4 And nanocubes of Fe 3 O 4 Has uniform morphology and side length of about 50nm, and the similar size is convenient for eliminating the size of the material to electrochemicalInfluence of properties of the extracted uranium. FIGS. 1 (c) and 1 (d) show two nano Fe' s 3 O 4 In the HRTEM photograph of the crystal, the lattice spacing of the lattice fringes parallel to the exposed crystal plane is 0.248nm, and the crystal plane is {222} crystal plane as the length of the lattice spacing. By contrast, nanocubes of Fe 3 O 4 Has two groups of interplanar spacings of 0.196nm and 0.291nm respectively corresponding to Fe 3 O 4 {200} crystal plane and {220} crystal plane. Obviously, the lattice fringes of the {200} crystal plane are parallel to the nanocube Fe 3 O 4 The square surface of (C) proves that {200} crystal face is nano-cube Fe 3 O 4 Exposing the crystal plane.
XRD test patterns revealed two nano Fe 3 O 4 The crystal structure of the crystal. FIG. 2 (a) shows nano Fe 3 O 4 The crystal has a plurality of peaks at 30.1 degrees, 35.4 degrees, 37.1 degrees, 43.1 degrees, 53.5 degrees, 57 degrees, 62.6 degrees and 74.1 degrees, which correspond to nano Fe respectively 3 O 4 {200}, {311}, {222}, {400}, {422}, {511} and {440} crystal planes of the crystal (JCPScarriage # 65-3107). At the same time, XRD patterns also illustrate nano Fe 3 O 4 The crystal is of a reverse spinel structure and has no other impurities. This was also confirmed by XPS spectra, as shown in FIG. 2 (b), for the two nano Fe 3 O 4 The crystal contains only signals of Fe and O elements.
(1) Nano octahedral Fe 3 O 4 Performance testing in uranium solutions
To investigate the effect of crystal plane effects on the extraction efficiency of uranium, the extraction performance of uranium was first tested in an electrolyte containing 8mg/L of simulated U (VI). Adopts a classical three-electrode system, takes Ag/AgCl as a reference electrode, takes a platinum wire as a counter electrode, and takes 100mL of 0.5M Na 2 SO 4 And 8mg/L U (VI) electrolyte. Taking the reduction voltage of uranium into consideration, extracting uranium from seawater by adopting the potential of-1.5V Vs Ag/AgCl, and obtaining the current density of 0.1-50 mA cm -2 As shown in fig. 3 (a). FIG. 3 (b) shows two nano-Fe 3 O 4 Extraction efficiency of crystal pair U (VI). After electrochemical uranium extraction for 480min, nano octahedral Fe 3 O 4 For U (VI)The extraction efficiency of (2) is 93.2%, and the nanocubes Fe 3 O 4 The extraction efficiency at 480min is only 63.0%, and the performance of the nano octahedron is far superior to that of a nano cube.
According to the principle of electrochemical extraction, the ions which are mainly tested by interfering ions are cations, and K+ and Zn are selected 2+ 、Cu 2+ 、Ni 2+ 、Co 2+ 、V 5+ And Mn of 2+ To test ions (based on uranyl ions and Ca in seawater) 2+ And Mg (magnesium) 2+ In the proportion of 8ppm of uranium, ca is prepared as a labeled seawater solution 2+ With Mg 2+ When the ion reaches a saturated state, the ion is selected to be tested in competitive ions), the interfering ions mainly conduct research on electrochemical selective extraction of uranium by single ions in the seawater, and Na with the concentration ratio of the single interfering ions to the uranium in the seawater being 0.5M is adopted 2 SO 4 Adding interference ions and uranyl ions for electrochemical extraction.
Competitive ion assay using the cations described above with Ca 2+ 、Mg 2+ Testing, namely preparing all the interference ions tested before into electrolyte according to the ratio of the interference ions to uranyl ions, and performing electrochemical extraction testing.
Evaluation of nanooctahedral Fe with interfering ion test in cyclic test 3 O 4 Is improved in terms of tamper resistance and durability. In the electrochemical uranium extraction experiment, the concentration of interfering ions and U (VI) (K + ，Zn 2+ ，Cu 2+ ，Ni 2+ ，V 5+ ，Co 2+ And Mn of 2+ ) Is added to the electrolyte. FIG. 4 (a) shows nano-octahedral Fe, respectively 3 O 4 Interfering ion test and cyclic test results. It can be seen that the electrochemical extraction efficiency of U (VI) still reaches more than 90% in the presence of various interfering ions, and the extraction efficiency is not reduced due to the presence of the interfering ions, which indicates nano octahedral Fe 3 O 4 Has certain anti-interference performance. FIG. 4 (b) shows nano-octahedral Fe 3 O 4 Is used as a desorption capacity of the catalyst. Electrochemical desorption was performed by applying a positive potential of +1.5V, and after 180min of electrochemical desorption, desorption was performedThe efficiency reached 71% of the initial concentration. After determining the desorption efficiency, we used a cyclic test to determine the durability and stability of the material. As shown in FIG. 4 (c), the efficiency of electrochemical uranium extraction can be maintained above 90% after 4 extraction-desorption cycles, and nano-octahedral Fe can be seen 3 O 4 Has good stability. Nano octahedral Fe 3 O 4 Has good anti-interference performance and stability, and has the potential of extracting uranium from seawater.
(2) Nano octahedral Fe 3 O 4 Performance testing in seawater
Electrolyte experiments were performed by configuring 8mg/L U (VI) with seawater to demonstrate the feasibility of the efficiency of the crystal face-regulated associated electrochemical extraction of uranium. A three-electrode constant-voltage test is adopted, and experiments are carried out on 8mg/L uranium-labeled seawater, which prove that nano octahedral Fe 3 O 4 The possibility of electrochemical seawater uranium extraction. FIG. 5 (a) shows nano-octahedral Fe 3 O 4 And nanocubes of Fe 3 O 4 Uranium extraction-time curve in uranium-labeled seawater. After electrochemical extraction for 8 hours, fe 3 O 4 The enrichment efficiency of the nano-powder reaches 91 percent, and the nano-cubic Fe 3 O 4 The enrichment efficiency of (2) was 76%. It can be seen that under the seawater environment of multi-ion coexistence, nanometer octahedral Fe 3 O 4 The uranium extraction efficiency of (2) is obviously higher than that of nano cubic Fe 3 O 4 . Meanwhile, the occupation condition of other coexisting interfering ions in the sea water on {222} surface active sites is evaluated by measuring the concentration of other competing ions in 8mg/L uranium-labeled sea water. As shown in FIG. 5 (b), in uranium-bearing seawater of 8mg/L, the competitive ion pair nano Fe in seawater was examined 3 O 4 The effect of uranium extraction by the crystal. The result shows that after 8 hours of electrochemical extraction, the uranium extraction efficiency reaches 91 percent, which is far higher than other competitive ions.
Nano octahedral Fe 3 O 4 The obvious extraction efficiency and anti-interference performance of the device can enable uranium extraction to be carried out in real seawater. For real seawater testing, a classical double electrode system was used to coat nano octahedral Fe 3 O 4 Is of carbon paper as yinThe electrode, pt wire electrode, was used as the counter electrode to test the extraction of uranium from real seawater. The electrochemical extraction of the real seawater is tested by adopting a constant current method, the current for limiting the test is-70 mA, and the electrochemical seawater uranium extraction experiment is continued for 8 hours. The effect of sea water volumes on electrochemical extraction efficiency was investigated by electrochemical extraction of real sea water of different volumes (1L, 2L, 4L, 6L, 8L, 10L). The test results are shown in fig. 6, and the extraction efficiency of the real seawater with different volumes can reach 50%. Electrochemical extraction in 10L of real seawater for 8h, and Fe 3 O 4 The nano-powder extracts 17.49 mug of uranium from natural seawater with an extraction amount of 3.49mg/g.
In order to better investigate the occurrence of uranium, the following characterization was performed. As shown in FIG. 7 (a), fe can be clearly observed 3 O 4 (PDF # 65-3107) and U 3 O 8 Characteristic peaks of (PDF # 74-2102) indicate the presence of good crystalline forms of U (V) and U (VI). After that, the electronic properties of the reacted material were further investigated by XPS spectroscopy. As shown in fig. 7 (b), XPS spectrum shows a signal peak of U, O, C, fe, and the presence of uranium species is consistent with the mapping results. As shown in fig. 7 (c), XPS spectra of U4 f were fitted to four peaks. The U4 f 7/2 signal peaks at 381eV and 381.98eV are assigned to U (V) and U (VI), respectively. The signal peaks for U4 f 5/2 are located at 391.88eV and 392.78eV, respectively, corresponding to U (V) and U (VI), respectively. Uranium species have both the valence states U (V) and U (IV), which is consistent with XRD results.
Two kinds of Fe were analyzed 3 O 4 The nanocrystals were subjected to uranium reduction potential to analyze differences in extraction performance. As can be seen from the linear scan curve test of FIG. 8, U (VI) is found in Fe 3 O 4 The reduction peaks on nanocubes and nanophase bodies lie in the range-0.3V to-0.5V, i.e. the transition of U (VI) to U (V), which illustrates the source of U (V) in the final extracted uranium product. In addition, nano octahedral Fe 3 O 4 Fe relative to nanocube 3 O 4 The nanocubes (0.442V) have a stronger uranium reduction negative potential (0.314V), indicating that the {222} plane is more conducive to uranium reduction.
Although embodiments of the present invention have been disclosed above, it is not limited to the details and embodiments shown and described, it is well suited to various fields of use for which the invention would be readily apparent to those skilled in the art, and accordingly, the invention is not limited to the specific details and illustrations shown and described herein, without departing from the general concepts defined in the claims and their equivalents.

Claims (8)

1. The application of the iron-based oxide in electrochemical seawater uranium extraction is characterized by comprising the following steps of:
step one, adding an iron-based oxide, carbon black and Nafion solution into absolute ethyl alcohol, then adding the Nafion solution, carrying out ultrasonic treatment for 0.5-1.5 hours to obtain a mixed solution, pasting a carbon felt on an electric heating plate at 50 ℃, uniformly coating the mixed solution on the carbon felt, continuing coating until the mixed solution is exhausted after the absolute ethyl alcohol volatilizes, obtaining a sample of the carbon felt uniformly loaded with the iron-based oxide,
step two, using the sample in the step one as a working electrode in a three-electrode system of an electrochemical workstation; the counter electrode in the three-electrode system is a platinum wire electrode, and the reference electrode is a silver/silver chloride electrode;
filtering the seawater by a 0.2 mu m filter, adding uranyl nitrate into the seawater to obtain simulated uranium seawater, adding the simulated uranium seawater into an electrolytic cell of a three-electrode system, and extracting uranium from the simulated uranium seawater by adopting the potential of-1.5V Vs Ag/AgCl.
2. Use of the iron-based oxide according to claim 1 for electrochemical uranium extraction from seawater, wherein the iron-based oxide is nano octahedral Fe 3 O 4 And the nano octahedral Fe 3 O 4 Nano Fe in octahedral shape for transmission electron microscope pattern 3 O 4 Crystalline, and nano Fe 3 O 4 The crystal has a {222} crystal plane.
3. Use of the iron-based oxide according to claim 1 for electrochemical uranium extraction from seawater, wherein step oneNano octahedral Fe 3 O 4 The preparation method of (2) comprises the following steps: adding ferric trichloride hexahydrate and sodium hydroxide into ethylene glycol, stirring for 0.5-1.5 hours, and ending stirring when the solution is changed from transparent clear to yellow transparent to obtain a mixture; transferring the mixture into a high-pressure reaction kettle, placing the mixture into an oven for hydrothermal reaction, reacting for 8-15 hours at 180-220 ℃, naturally cooling to room temperature, centrifuging by a centrifuge, washing by using deionized water and absolute ethyl alcohol, and drying to obtain nano octahedral Fe 3 O 4 。
4. Use of the iron-based oxide according to claim 3 for electrochemical uranium extraction from seawater, wherein the molar ratio of ferric trichloride hexahydrate to sodium hydroxide is 1:3-7; the mol volume ratio of the ferric trichloride hexahydrate to the ethylene glycol is 1 mmol:8-12 mL.
5. The use of the iron-based oxide according to claim 1 in electrochemical seawater uranium extraction, wherein the mass ratio of the iron-based oxide to carbon black is 4-6:3; the mass volume ratio of the iron-based oxide to the absolute ethyl alcohol is 4-6 mg: 1-3 mL; the mass volume ratio of the iron-based oxide to the Nafion solution is 4-6 mg:30-40 mu L; the concentration of the Nafion solution was 0.5wt%.
6. Use of the iron-based oxide according to claim 1 for electrochemical uranium extraction from seawater, wherein the carbon felt is cut to be high: the width is 1cm: a 2cm quadrilateral shape was used.
7. The use of the iron-based oxide according to claim 1 for electrochemical extraction of uranium from seawater, wherein the concentration of uranyl nitrate in simulated uranium seawater is between 0.1 and 100mg/L.
8. Use of the iron-based oxide according to claim 1 for electrochemical uranium extraction from seawater, wherein the substitution of step two is: using the sample of step one as a cathode in a two-electrode system; pt wire electrode was used as the counter electrode;
filtering natural seawater by a 0.2 mu m filter, then adding the filtered natural seawater into an electrolytic cell, and adopting a constant current method to limit the tested current to-70 mA, and continuously extracting uranium from the electrochemical seawater for 5-24 hours.
CN202310535706.7A 2023-05-12 2023-05-12 Application of iron-based oxide in electrochemical seawater uranium extraction Pending CN116607176A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115287671A (en) * 2022-06-29 2022-11-04 西南科技大学 Preparation and application of sulfur-based iron oxide nanowire for extracting uranium from electrochemical seawater

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115287671A (en) * 2022-06-29 2022-11-04 西南科技大学 Preparation and application of sulfur-based iron oxide nanowire for extracting uranium from electrochemical seawater
CN115287671B (en) * 2022-06-29 2024-05-10 西南科技大学 Preparation and application of sulfo-ferric oxide nanowire for electrochemical seawater uranium extraction

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