An oxygen-enriched vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, a preparation method and application of the composite electrode material in adsorbing uranium

Abstract

The application discloses an oxygen-enriched vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material and a preparation method and application thereof in adsorbing uranium. The tungsten chloride is used as a precursor, is dissolved in a reducing agent ethanol through ultrasonic treatment, carboxylated multi-walled carbon nanotubes are added to enhance the conductivity of the electrode material, and the carboxylated multi-walled carbon nanotubes are dispersed through ultrasonic treatment again. Finally, the oxygen-enriched vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material WO 3‑x / MWCNTs-COOH is synthesized through a solvothermal reaction. The oxygen-enriched vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material prepared by the application can reach an adsorption capacity of 107.6 mg·g ‑1 -1 for uranium at pH=4. The uranium ion is quickly adsorbed and saturated, the adsorption capacity of the electro-adsorption reaches 1.2 times of the adsorption capacity under the condition of no power supply, and the required time is only 2 / 5 of the static adsorption.

Description

Technical Field

[0001] This invention belongs to the field of radioactive nuclide uranium processing and electroadsorption material preparation technology, specifically relating to an oxygen-rich vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, its preparation method, and its application in uranium adsorption. Background Technology

[0002] In the nuclear industry, uranium ( 235 Uranium (U) is used as a primary nuclear element in energy production and is typically obtained through mining. With increasing energy demand, uranium mining output has doubled annually; however, uranium resources are finite, and terrestrial uranium deposits are projected to be depleted by this century. Meanwhile, uranium (U) 235 U is one of the most dangerous radioactive isotopes in nuclear wastewater, with a long half-life (t). 1 / 2 =1.0×10 5 ~4.5×10 9 It has the characteristics of being non-biodegradable and highly durable in the environment. 235 U is mainly present in nuclear wastewater as uranyl ions (UO2). 2+ Uranium, due to its radiation and chemical toxicity, can cause permanent damage to the ecological environment and human health. Therefore, the rapid and efficient extraction of uranium from radioactive wastewater is crucial for the sustainable development of energy and the environment.

[0003] UO2 2+ Methods for removing ions from aqueous solutions have been extensively studied, including adsorption, biological methods, ion exchange, and membrane separation. In recent years, electrochemical adsorption, which eliminates the need for large amounts of chemical regenerators or direct heat and pressure inputs required by traditional adsorption methods, has become a highly attractive ion removal technique for water purification and environmental remediation. Electrochemical adsorption not only possesses large adsorption capacity, good regeneration performance, and selectivity, but also offers advantages such as environmental friendliness, rapid kinetics, and simple operation, making it a popular choice among various separation methods.

[0004] Electrochemical adsorption materials need to possess a large number of adsorption active sites and a certain degree of conductivity. Tungsten trioxide (WO3) has been reported as a low-cost material for the electroadsorption of uranyl ions. Zhou et al. prepared a flower-like WO3 / C composite material as a pseudocapacitive electrode material for the electroadsorption of U(VI) from water. Recent reports have proposed oxygen-vacancy tungsten trioxide (WO3)... 3-x It has a natural affinity for uranyl ions. Compared to WO3, the introduction of oxygen vacancies (OVs) makes WO3 more compatible with uranyl ions. 3-x It possesses higher charge transfer efficiency and redox capability. Yang et al. synthesized a WO3-... 3-x The nanowires achieved an adsorption capacity of 337 mg·g for uranyl ions. -1 In order to further improve WO3-x The carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) are introduced to composite the electrode material to improve the electrical conductivity of the electrode material. SUMMARY

[0005] The present application synthesizes the oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material by a solvothermal method, and studies the uranium adsorption capacity of the electrode material. The adsorption capacity of the electrode material synthesized under different proportions is obtained by changing the experimental conditions. The adsorption saturation is achieved in 2h, and the adsorption capacity is 1.2 times of the static adsorption.

[0006] The present application is realized by the following technical scheme: an oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, and a preparation method comprising the following steps:

[0007] 1) A mixture of concentrated nitric acid and concentrated sulfuric acid is added to the multi-walled carbon nanotubes, and after ultrasonic dispersion, the mixture is placed in a water bath kettle, heated and stirred vigorously to obtain a multi-walled carbon nanotube dispersion liquid; after cooling, the obtained dispersion liquid is diluted with deionized water, washed until the filtrate is neutral, and the obtained sample is placed in a vacuum oven for drying to obtain carboxylated multi-walled carbon nanotubes;

[0008] 2) WCl6 is placed in a beaker, anhydrous ethanol is added, and ultrasonic is performed until the solid is completely dissolved to obtain a bright yellow solution; the carboxylated multi-walled carbon nanotubes obtained in step 1) are added to the obtained solution, and ultrasonic is performed again until the carboxylated multi-walled carbon nanotubes are completely dispersed; the dispersion liquid is transferred to a reaction kettle, and is placed in an oven for solvothermal reaction; after cooling, the product is washed by centrifugation with anhydrous ethanol for several times, and is vacuum dried at 60℃ for 12h to obtain the oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material.

[0009] In step 1) of the above oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:2-4.

[0010] In step 1) of the above oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, 0.1-0.2g of multi-walled carbon nanotubes is added to 20mL of the mixture of concentrated sulfuric acid and concentrated nitric acid.

[0011] In step 2) of the above oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, 0.05-0.08g of tungsten chloride is added to 54mL of anhydrous ethanol.

[0012] The oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material of the above, in step 2), the mass ratio of tungsten chloride: carboxylated multi-walled carbon nanotube is 1:0.06250~0.1875.

[0013] The oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material of the above, in step 2), the solvothermal reaction is carried out at 180℃ for 12h.

[0014] An electrode comprising the oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material of the above, the electrode material is mixed with electrode liquid and then dropped on carbon cloth to prepare the electrode, and the volume ratio of the electrode liquid is dehydrated ethanol: deionized water: Nafion = 10~20: 2~5: 0.5~1.

[0015] The electrode of the above, in step 2), 1~2mg of the oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material is added to 50μL of the electrode liquid.

[0016] The electrode of the above is used as an adsorbent for adsorbing radionuclide uranium.

[0017] The application of the above is as follows: a solution containing uranium ions is taken, the pH of the solution is adjusted to 2~7, the electrode of the above is used as a cathode, and the electrode is adsorbed for 2h under a voltage of-1.2V.

[0018] The beneficial effects of the present application are:

[0019] 1) The oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material of the present application contains a large number of active sites that can adsorb uranyl ions. After the multi-walled carbon nanotube is carboxylated, the oxygen vacancy-rich tungsten trioxide is compounded with it through a solvothermal reaction, thereby increasing the conductivity of the electrode material.

[0020] 2) The oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material prepared by the present application has a green and environmentally friendly synthesis path, the adsorption active sites of the synthesized electrode material are abundant, the material structure is stable, the conductivity is strong, the adsorption kinetics is fast, and it has certain practical application potential.

[0021] 3) The raw materials of the present application are low in price, the reaction is fast and efficient, and no expensive catalyst is needed, and the prepared electrode material can be used for the treatment of uranium elements in water pollution.

[0022] 4) The present application is helpful to solve the problem of long time consumption in traditional adsorption.

[0023] 5) The adsorption kinetics prepared by the present application is fast, and in the pH=2~7 range, the uranyl ions in the solution have a certain adsorption capacity, and the maximum adsorption capacity of the uranyl ions is 107.6mg·g-1 .

[0024] In summary, the oxygen-vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material prepared by this invention can effectively adsorb uranyl ions. Moreover, the preparation process is simple, the conductivity is good, the adsorption efficiency is high, and the adsorption kinetics are fast, which shows certain practical potential. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the synthesis of oxygen-vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material.

[0026] Figure 2 It is an oxygen-vacancy tungsten trioxide (A) and an oxygen-vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material (WO). 3-x Scanning electron microscope image of / MWCNTs-COOH)(B).

[0027] Figure 3 This is the infrared spectrum of the oxygen-vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material.

[0028] Figure 4 This is a comparison of the adsorption performance of oxygen-vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode materials for uranium at pH 2–7.

[0029] Figure 5 This is a comparison chart of the adsorption performance of oxygen-vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode materials for uranium under different synthesis conditions.

[0030] Figure 6 It is an oxygen-vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material (WO3). 3-x Fitting plot of the adsorption isotherm of uranium ( / MWCNTs-COOH) at pH=4.

[0031] Figure 7 It is an oxygen-vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material (WO3). 3-x The curve showing the change in the electroadsorption capacity of uranium by 0.0100MWCNTs-COOH over time at pH=4.

[0032] Figure 8 It is an oxygen-vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material (WO3). 3-x First-order kinetic curve of static adsorption of uranium (0.0100MWCNTs-COOH) at pH=4. Detailed Implementation

[0033] The present invention will be further illustrated below with specific embodiments, but these embodiments do not limit the scope of the invention.

[0034] Example 1 electrode material synthesized with different amounts of carboxylated multi-walled carbon nanotubes

[0035] 1. WO 3-x / 0.0050 MWCNTs-COOH

[0036] 1) Put 0.5 g of multi-walled carbon nanotubes into a round-bottom flask, add 100 mL of a mixture of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, ultrasonically disperse for 1 h, then place in a water bath, heat at 40°C and stir vigorously for 2 h to obtain a carboxylated multi-walled carbon nanotube dispersion; after cooling, dilute the obtained dispersion with deionized water, suction filter to obtain a solid, wash again until the filtrate is neutral, and place the obtained sample in a vacuum oven, dry at 80°C for 12 h to obtain carboxylated multi-walled carbon nanotubes.

[0037] 2) Take 0.08 g of WCl6 and put it into a beaker, add 54 mL of anhydrous ethanol, ultrasonically dissolve until the solid is completely dissolved, to obtain a bright yellow solution; add 0.0050 g of carboxylated multi-walled carbon nanotubes obtained in 1) to the obtained solution, ultrasonically disperse again until the carboxylated multi-walled carbon nanotubes are completely dispersed; transfer the dispersion to a reaction kettle, place in an oven at 180°C for solvothermal reaction for 12 h, after cooling, centrifuge the product with anhydrous ethanol several times, vacuum dry at 60°C for 12 h, to obtain an oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, named as WO 3-x / 0.0050 MWCNTs-COOH.

[0038] 2. WO 3-x / 0.0075 MWCNTs-COOH

[0039] Prepared according to the method described in 1), except that 0.0075 g of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) is used instead of 0.0050 g of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) in step 2) of 1), to obtain an oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, named as WO 3-x / 0.0075 MWCNTs-COOH.

[0040] 3. WO 3-x / 0.0100 MWCNTs-COOH

[0041] Prepared according to the method described in 1), except that 0.0100 g of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) is used instead of 0.0050 g of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) in step 2) of 1), to obtain an oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, named as WO 3-x / 0.0100 MWCNTs-COOH.

[0042] 4、WO 3-x / 0.0125MWCNTs-COOH

[0043] Prepared according to the method described in 1, except that 0.0125 g of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) was used instead of 0.0050 g of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) in step 2) of 1 to obtain an oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, designated as WO 3-x / 0.0125MWCNTs-COOH.

[0044] 5、WO 3-x / 0.0150MWCNTs-COOH

[0045] Prepared according to the method described in 1, except that 0.0150 g of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) was used instead of 0.050 g of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) in step 2) of 1 to obtain an oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material, designated as WO 3-x / 0.0150MWCNTs-COOH.

[0046] Characterization

[0047] 1、 Figure 2 are scanning electron micrographs of oxygen vacancy-rich tungsten trioxide (A) and tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material (WO 3-x / 0.0100MWCNTs-COOH) (B). The tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material was prepared according to the method described in 1, except that 0.0100 g of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) was used instead of 0.050 g of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) in step 2) of 1. Figure 2 It can be seen that the oxygen vacancy-rich tungsten trioxide is interwoven in a linear form after being combined with the multi-walled carbon nanotubes, which indicates that in addition to containing a large number of adsorption active sites, it also has an interlaced structure that can effectively transfer mass.

[0048] 2、 Figure 3 is an infrared spectrum of the tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material. WO 3-x , WO 3-x / 0.0100MWCNTs-COOH respectively represent the electrode material without the addition of carboxylated multi-walled carbon nanotubes, and the electrode material with the addition of 0.0100 g of multi-walled carbon nanotubes. As shown in Figure 3 , the characteristic peaks of the oxygen vacancy-rich tungsten trioxide before and after being combined with the multi-walled carbon nanotubes are basically consistent, but the peak at 3300 cm -1 nearby WO 3-x and WO 3-xThe intensity of the wide scattering peak of WO 0.0100MWCNTs-COOH is different, which may be due to the addition of carboxylated multi-walled carbon nanotubes affecting the number of hydroxyl groups on the surface of tungsten atoms. Compared with WO 3-x , the infrared absorption peaks of WO 3-x 0.0100MWCNTs-COOH at 1000cm -1 -500cm -1 -1cm 3-x are weakened to varying degrees, which may be due to the addition of carboxylated multi-walled carbon nanotubes affecting the crystallization of oxygen vacancy tungsten trioxide to some extent. In summary, the oxygen vacancy tungsten trioxide and carboxylated multi-walled carbon nanotube composite form the WO 3-x 0.0100MWCNTs-COOH electrode material.

[0049] (1) The adsorption effect of the oxygen vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material on uranium at different acidities

[0050] Method: 4mg of WO 3-x 0.0100MWCNTs-COOH prepared in Example 1 was weighed, 150μL of absolute ethanol, 40μL of water and 10μL of Nafion were added and ultrasonically dispersed to prepare an electrode solution, which was dropped on a 1.5cm×1cm carbon cloth to prepare a working electrode.

[0051] A solution containing uranium ions was taken, the pH of the solution was adjusted to 2-7, and the above working electrode was used as the cathode and a carbon rod was used as the anode at a voltage of-1.2V for 2h of electric adsorption.

[0052] From the above table, it can be seen that as the pH of the uranium solution increases, the adsorption rate of the electrode material on uranium shows a trend of first increasing and then decreasing, which may be because at pH=2 and pH=3, hydrogen ions and uranyl ions are both cations, forming competition, resulting in hydrogen ions being the main migration object under the action of the electric field, and the adsorption rate is relatively low. At pH=4, the main form of uranium is uranyl ions, which is the main adsorption object of oxygen vacancy tungsten trioxide, and the proportion of hydrogen ions is relatively small, so the adsorption rate of uranium reaches a peak of 85.8% under this condition. Subsequently, the form of uranium changes from uranyl ions to other forms, so the adsorption rate decreases. Figure 4 (2) The adsorption effect of electrode materials with different raw material ratios on uranium

[0053] Method: 4mg of WO 3-x 0.0100MWCNTs-COOH, WO 3-x 0.0075MWCNTs-COOH and WO3-x / 0.0100MWCNTs-COOH, WO 3-x / 0.0125MWCNTs-COOH, WO 3-x / 0.0150MWCNTs-COOH, add 150μL anhydrous ethanol, 40μL water and 10μL Nafion and ultrasonically disperse to prepare electrode solution, drop it onto 1.5cm×1cm carbon cloth to make working electrode.

[0055] Depend on Figure 5 It can be seen that with the increase of the amount of carboxylated multi-walled carbon nanotubes added, the adsorption rate of uranium by the electrode material first increases and then decreases, reaching a peak at an addition amount of 0.0100 g. Increasing the amount of carboxylated multi-walled carbon nanotubes is beneficial to enhancing the conductivity of the electrode material; however, adding too many carboxylated multi-walled carbon nanotubes will affect the crystallinity of oxygen-vacant tungsten trioxide, reducing the number of adsorption active sites. Therefore, the adsorption rate tends to decrease when the amount of carboxylated multi-walled carbon nanotubes exceeds 0.0100 g. In conclusion, an addition amount of 0.0100 g of carboxylated multi-walled carbon nanotubes is the optimal ratio.

[0056] (III) Optimal Synthesis Ratio of Electrode Materials (WO 3-x The adsorption isotherm method for U(VI) electroadsorption of 0.010MWCNTs-COOH was performed by taking 10mL, 15mL, 20mL, 25mL, 30mL, 35mL, 40mL, 45mL, and 50mL of U(VI) at a concentration of 20mg·L⁻¹. -1 The pH of the U(VI) solution was adjusted to 4. Then, WO3 was used as the solvent. 3-x Using 0.0100MWCNTs-COOH as the working electrode, adsorption was performed at 25℃ and -1.2V for 2 hours. The results are as follows: Figure 6 .

[0057] Acidity experiments have shown that at pH=4, WO3 3-x The adsorption effect of 0.0100MWCNTs-COOH was optimal. Therefore, the saturated adsorption capacity of the electrode material was measured at pH=4, and the experimental data were fitted using Langmuir, Freundlich, and Temkin adsorption isotherm models. The fitting results are as follows: Figure 6 As shown, the fitting values ​​R of the four models are... 2 The values ​​are 0.99, 0.94, and 0.92 respectively. This indicates that WO 3-x The adsorption isotherm of U(VI) for 0.0100MWCNTs-COOH is more consistent with the Langmuir model, and the maximum adsorption capacity for U(VI) is 107.6 mg·g⁻¹. -1This indicates that the adsorption of U(VI) on the adsorbent is a monolayer adsorption process, and the adsorption sites of the adsorbent are uniformly dispersed on the surface of the adsorbent.

[0058] (IV) Optimal synthesis ratio of electrode material (WO 3-x / 0.010MWCNTs-COOH) adsorbing U(VI) kinetics curve comparison

[0059] Method: Take two 10mL, 15mL, 20mL, 25mL, 30mL, 35mL, 40mL, 45mL, 50mL concentrations of 20mgL -1 U(VI) solution, adjust pH to 4. Add 4mg electrode material to one, shake and adsorb at 25℃ to get Figure 8 . The other is subjected to electro-adsorption by the method in Example 2(ii) to get Figure 7 .

[0060] By comparing Figure 7 and Figure 8 , we find that the adsorption saturation time of the electrode material after electrification is greatly reduced, only 2 / 5 of the non-electrified condition, and the adsorption capacity after electrification also increases by 1.2 times of the non-electrified condition.

Claims

1. The application of an electrode containing an oxygen-vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material as an adsorbent in the electroadsorption of the radioactive nuclide uranium, characterized in that, The method is as follows: take a solution containing uranium ions, adjust the pH of the solution to 4, use an electrode containing oxygen-rich vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material as the cathode, and perform electroadsorption for 2 h at a voltage of -1.2 V; The preparation method of the oxygen-rich vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material includes the following steps: 1) Add a mixture of concentrated nitric acid and concentrated sulfuric acid to multi-walled carbon nanotubes, disperse them by ultrasonication, place them in a water bath, heat and stir vigorously to obtain a multi-walled carbon nanotube dispersion; after cooling, dilute the obtained dispersion with deionized water, wash until the filtrate is neutral, and dry the obtained sample in a vacuum oven to obtain carboxylated multi-walled carbon nanotubes. 2) Place WCl6 in a beaker, add anhydrous ethanol, and sonicate until the solid is completely dissolved to obtain a bright yellow solution; add the carboxylated multi-walled carbon nanotubes obtained in step 1) to the solution, with a mass ratio of tungsten chloride to carboxylated multi-walled carbon nanotubes of 1:0.06250~0.1875; sonicate again until the carboxylated multi-walled carbon nanotubes are completely dispersed; transfer the dispersion to a reaction vessel, place it in an oven for solvothermal reaction, cool, and wash the product multiple times with anhydrous ethanol by centrifugation, then vacuum dry at 60 ℃ for 12 h to obtain an oxygen-vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material; The electrode containing the oxygen-vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material is made by mixing the oxygen-vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material with an electrode solution and then dropping it onto carbon cloth. The electrode solution is prepared by volume ratio of anhydrous ethanol: deionized water: Nafion = 10~20: 2~5: 0.5~1. Add 1–2 mg of oxygen-rich vacancy tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material to every 50 µL of electrode solution.

2. The application of the electrode containing an oxygen-vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material as an adsorbent in the electroadsorption of radioactive uranium nuclide, as described in claim 1, is characterized in that... In step 1), the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:2~4.

3. The application of the electrode containing an oxygen-vacancy-rich tungsten trioxide / carboxylated multi-walled carbon nanotube composite electrode material as an adsorbent in the electroadsorption of radioactive uranium nuclide, as described in claim 1, is characterized in that... In step 2), the solvothermal reaction is carried out at 180 °C for 12 h.

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