Carbon-coated TiO2 hollow tube capacitive deionization adsorption electrode material and preparation method thereof

Abstract

The invention discloses a carbon-coated TiO2 hollow tube capacitive deionization adsorption electrode material and a preparation method thereof. An active material is a carbon-coated TiO2 hollow nanotube as an electrode, the TiO2 hollow nanotube is obtained by combining a hydrothermal reaction of a titanium precursor in a mixed solution system of diethyl ether, ethanol and glycerol, and the carbon-coated TiO2 hollow nanotube is prepared by adopting a thermal reduction chemical method and has rich oxygen vacancies and an excellent hollow nanotube structure; the material can be effectively applied to the field of light-enhanced electro-adsorption of nuclide ions; according to the invention, a light-enhanced capacitance denuclide device is assembled through a carbon-coated TiO2 hollow tube capacitance deionization adsorption electrode material, and compared with a traditional carbon-based capacitance denuclide device, the light-enhanced capacitance denuclide device is better in ion selectivity, stronger in capability of adsorbing ions in water and higher in circulation rate.

Description

Technical Field

[0001] The present invention belongs to the field of nuclear pollution prevention and control, and in particular relates to a carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material and a preparation method thereof. Background Art

[0002] Since the mid-20th century, nuclear energy, as an important form of energy, has become part of the global energy supply. However, with the continuous development of nuclear energy utilization, the radioactive wastewater generated in the nuclear energy process, especially wastewater containing radionuclides such as uranium (U), cesium (Cs), and strontium (Sr), poses a great potential threat to the natural environment and human health. The treatment and disposal of this wastewater has become a focus of global attention. Traditional radionuclide removal methods such as physical adsorption, filtration, chemical precipitation, and bioremediation, although effective to a certain extent, often face problems such as complex operation, high cost, unstable treatment effect, and the potential for secondary contamination. How to safely, effectively, and economically remove radionuclides from wastewater remains a major challenge that needs to be addressed.

[0003] Capacitive deionization (CDI) is an emerging water treatment technology with the advantages of high efficiency, energy conservation, and environmental friendliness. Existing CDI technology uses carbon-based electrodes to absorb ions from water through the double-layer effect. However, due to the poor ion absorption capacity, low circulation rate, and lack of ion selectivity of conventional carbon-based electrode materials, it is difficult to meet the needs of nuclear wastewater treatment. Summary of the Invention

[0004] Based on the above shortcomings of the prior art, the present invention provides a carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material and a preparation method. 2-x @C) as the active material of the photoelectrode, and then a capacitive adsorption photoelectrode was prepared. This electrode was then used to assemble a light-enhanced capacitive denucliding device. Compared to traditional carbon-based capacitive denucliding devices, this device exhibits better ion selectivity, stronger ion adsorption capacity in water, and a higher recycle rate.

[0005] To achieve the above object, the present invention provides the following technical solutions: The present invention provides a carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material. The active material is in the form of nanotubes and consists of carbon-wrapped TiO2 hollow nanotubes. A large number of TiO2 nanosheets exist on the surface of the nanotubes.

[0006] The present invention also provides a method for preparing a carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material, comprising the following steps: S1. Preparation of TiO2 precursor: Add a titanium source to a mixed solvent of glycerol, ethanol, and ether. Stir thoroughly for 30-60 minutes, then transfer to a hydrothermal autoclave and heat at 100-140°C for 12-36 hours. Centrifuge, wash, dry, and grind to obtain the TiO2 precursor.

[0007] S2. Preparation of TiO 2-x @C: The TiO2 precursor prepared in step S1 is calcined in a crucible at 500-900℃ for 1-5h in a hydrogen / argon mixed gas environment with a heating rate of 5℃ / min to obtain TiO 2-x @C; S3, Capacitive deionization adsorption electrode material: Take the TiO obtained in step S2 2-x @C After adding N-methylpyrrolidone and grinding, Ketjen black and adhesive PVDF were added, among which TiO 2-x The weight ratio of @C, Ketjen black, and PVDF is 80:5:5. After being ground evenly, they are coated on the current collector titanium mesh and dried to obtain a capacitive denuclearized photoelectrode.

[0008] It is a further preferred method for preparing a carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material.

[0009] Preferably, the titanium source in step S1 is one of titanyl sulfate, titanyl nitrate and titanyl chloride.

[0010] Preferably, the ratio of hydrogen to argon gas mixture in step S2 is 5:95.

[0011] Preferably, the amount of the titanium source added in step S1 is 1-3 g, the total volume of the mixed solvent of glycerol, ethanol and diethyl ether is 50-100 mL, wherein the ratio of glycerol, ethanol and diethyl ether is 1:3:1, preferably the ratio of glycerol, ethanol and diethyl ether is 1:2:1; The amount of the TiO2 precursor added in step S2 is 0.4~0.6g.

[0012] The present invention also provides a light-enhanced capacitance nuclide removal device.

[0013] The device uses the prepared carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material as the negative electrode, the electrode using carbon material as the active material as the positive electrode, and an externally applied visible light source and power supply.

[0014] The present invention also provides an application of a light-enhanced capacitive nuclide removal device for nuclide purification. The nuclides are one or a combination of two or more of uranyl, strontium, and cesium ions, present in the form of a solution, with a nuclide ion concentration of 1-200 ppm, and anions are one or a combination of two or more of chloride, nitrate, and sulfate ions. The voltages of the positive and negative electrodes are both 0.6-1.2 V, and the adsorbed positive and negative electrodes are regenerated by short-circuiting.

[0015] The beneficial effects of the present invention compared to the prior art are: (1) Compared with the traditional carbon-based capacitor denucliding device, the light-enhanced capacitor denucliding device provided by the present invention has better ion selectivity, stronger ability to adsorb ions in water, and higher circulation rate.

[0016] (2) The light-enhanced capacitive denucliding device provided by the present invention is simple to operate when performing electrosorption. It can effectively remove nuclide ions in water by simply combining an external visible light source with traditional capacitive adsorption technology. In the preferred embodiment, the volume ratio of glycerol, ethanol, and ether is 1:2:1 to obtain TiO 2-x @C electrode, the effect is better and has better adsorption capacity.

[0017] (3) In the prior art, after the electrode material is coated on the surface of the metal current collector, the active sites on the outer surface serve as the main nuclide adsorption sites. The present invention combines a visible light source to irradiate the back of the current collector to stimulate the active sites at the bottom of the current collector and enhance the activity of the adsorbed nuclide. At the same time, the active material of the present invention is selected from carbon-wrapped hollow titanium dioxide hollow nanotube composite electrode TiO 2-x @C has good photocatalytic activity, a large number of internal oxygen vacancies and a customized hollow structure, which also accelerates the transmission of electrons and can be effectively used in the field of electrosorption to remove radionuclide ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the light-enhanced capacitive denucliding device for performing nuclide adsorption; Figure 2 The TiO prepared in Example 1 2-x XRD pattern of @C; Figure 3 The TiO prepared in Example 1 2-x @SEM image of C; Figure 4 The TiO prepared in Example 1 2-x TEM image of @C; Figure 5 The TiO prepared in Example 1 2-x XPS graph of @C, Figure (a) captures the Ti 3+Trajectory,(b) captures the O vacancy; Figure 6 The TiO prepared in Example 2 2-x TEM image of @C; Figure 7 The TiO prepared in Example 1 2-x @C electrode treated the solution of system 1 under visible light and 1.2V voltage; Figure 8 The TiO prepared in Example 1 2-x @The effect diagram of C electrode treating adsorption system 1 solution at different voltages; Figure 9 The TiO prepared in Example 1 2-x @The effect of C electrode adsorbing the second solution of the system at 1.2V; Figure 10 The TiO prepared in Example 1 2-x @C electrode adsorption of UO2 in system 1 solution at different pH ranges at 1.2V 2 + Effect diagram of ions; Figure 11 The TiO prepared in Example 1 2-x @C electrode cycled for 10ppm UO2 at 1.2V 2+ Adsorption test diagram in solution; Figure 12 The TiO prepared in Example 1 2-x @C electrode cycle was used to purify three solutions of the adsorption system at a voltage of 1.2V; Figure 13 For the control example, 10ppm UO2 2+ Electrosorption experiments in single ion solutions. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] The present invention is described below by means of specific examples and comparative examples. Example 1

[0021] This embodiment provides a carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material, a preparation method, and a light-enhanced capacitor deionization device.

[0022] Preparation method: S1. Preparation of TiO2 precursor: Add 2 g of titanyl sulfate to 70 mL of a mixed solvent of glycerol, ethanol, and ether (in a 1:3:1 ratio). Stir thoroughly for 40 minutes, transfer to a hydrothermal reactor, and heat in an oven at 120°C for 24 hours. Centrifuge, wash, dry, and grind to obtain the TiO2 precursor.

[0023] S2. Preparation of TiO 2-x @C: 0.5 g of TiO2 precursor was placed in a crucible and calcined at 700 °C for 3 h in a hydrogen / argon mixed gas environment (hydrogen:argon = 5:95) with a heating rate of 5 °C / min. Finally, TiO 2-x @C; S3. Preparation of capacitive adsorption photoelectrode: Take TiO 2-x @C After adding N-methylpyrrolidone and grinding, Ketjen black and adhesive PVDF were added, among which TiO 2-x The weight ratio of @C, Ketjen black, and PVDF is 80:5:5. After grinding evenly, apply it on the current collector titanium mesh and dry it to obtain a capacitive denuclearized photoelectrode. S4. Using the photoelectrode prepared in step S3 as the negative electrode and the electrode using the carbon material as the active material as the positive electrode, a light-enhanced capacitive nuclide removal device is formed, and the device is used to perform photoelectric adsorption of nuclide ions.

[0024] A carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material is prepared by the above method.

[0025] Light-enhanced capacitance denucliding device: The prepared carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material is used as the negative electrode, the electrode using the carbon material as the active material is used as the positive electrode, and an externally applied visible light source and power supply are used.

[0026] The TiO prepared in Example 1 2-x @C conducted relevant measurements, and the results are attached. Figure 2-5 .

[0027] Figure 2 The TiO prepared in Example 1 2-x The XRD pattern of @C shows that its diffraction peaks are consistent with those of standard cards JCPDS 21-1276 and 21-1262, thus confirming the successful synthesis of TiO2.

[0028] Figure 3 The TiO prepared in Example 1 2-x @C SEM and TEM images show that TiO 2-x @CThe microscopic morphology of the synthesized material is hollow nanotubes, and there are a large number of nanosheets on the surface.

[0029] Figure 4The TiO prepared in Example 1 2-x @C TEM image, from which we can see TiO 2-x The microstructure of the material synthesized by @C is a hollow structure with a large number of nanosheets on the surface.

[0030] Figure 5 The TiO prepared in Example 1 2-x From the XPS graph of @C, we can see that Ti 3+ defects, (b) capturing abundant oxygen vacancies. Example 2

[0031] Refer to Example 1, except that: in step S2, the TiO 2-x When preparing @C, glycerol, ethanol and ether are mixed in a ratio of 1:1:1.

[0032] The TiO prepared in Example 2 2-x @C conducted relevant measurements, and the results are attached. Figure 6 , the nanosheets on the surface are obviously rougher and denser. Example 3

[0033] This embodiment provides a carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material, a preparation method, and a light-enhanced capacitor deionization device.

[0034] Preparation method: S1. Preparation of TiO2 precursor: Add 1 g of titanium oxynitrate to 50 mL of a mixed solvent of glycerol, ethanol, and diethyl ether (1:2:1). Stir thoroughly for 30 minutes, transfer to a hydrothermal reactor, and heat in an oven at 100°C for 12 hours. Centrifuge, wash, dry, and grind to obtain the TiO2 precursor.

[0035] S2. Preparation of TiO 2-x @C: 0.4 g of TiO2 precursor was placed in a crucible and calcined at 500 °C for 1 h in a hydrogen / argon mixed gas environment (hydrogen:argon = 5:95) with a heating rate of 5 °C / min. Finally, TiO 2-x @C; S3. Preparation of capacitive adsorption photoelectrode: Take TiO 2-x @C After adding N-methylpyrrolidone and grinding, Ketjen black and adhesive PVDF were added, among which TiO 2-x The weight ratio of @C, Ketjen black, and PVDF is 80:5:5. After grinding evenly, apply it on the current collector titanium mesh and dry it to obtain a capacitive denuclearized photoelectrode. S4. Using the photoelectrode prepared in step S3 as the negative electrode and the electrode using the carbon material as the active material as the positive electrode, a light-enhanced capacitive nuclide removal device is formed, and the device is used to perform photoelectric adsorption of nuclide ions.

[0036] A carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material is prepared by the above method.

[0037] Light-enhanced capacitance denucliding device: The prepared carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material is used as the negative electrode, the electrode using the carbon material as the active material is used as the positive electrode, and an externally applied visible light source and power supply are used. Example 4

[0038] This embodiment provides a carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material, a preparation method, and a light-enhanced capacitor deionization device.

[0039] Preparation method: S1. Preparation of TiO2 precursor: Add 3 g of titanium oxychloride to 100 mL of a mixed solvent of glycerol, ethanol, and ether (in a 1:2:1 ratio). Stir thoroughly for 60 minutes, transfer to a hydrothermal reactor, and heat in an oven at 140°C for 36 hours. Centrifuge, wash, dry, and grind to obtain the TiO2 precursor.

[0040] S2. Preparation of TiO 2-x @C: 0.6 g of TiO2 precursor was placed in a crucible and calcined at 900 °C for 5 h in a hydrogen / argon mixed gas environment (hydrogen:argon = 5:95) with a heating rate of 5 °C / min to obtain TiO 2-x @C; S3. Preparation of capacitive adsorption photoelectrode: Take TiO 2-x @C After adding N-methylpyrrolidone and grinding, Ketjen black and adhesive PVDF were added, among which TiO 2-x The weight ratio of @C, Ketjen black, and PVDF is 80:5:5. After grinding evenly, apply it on the current collector titanium mesh and dry it to obtain a capacitive denuclearized photoelectrode. S4. Using the photoelectrode prepared in step S3 as the negative electrode and the electrode using the carbon material as the active material as the positive electrode, a light-enhanced capacitive nuclide removal device is formed, and the device is used to perform photoelectric adsorption of nuclide ions.

[0041] A carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material is prepared by the above method.

[0042] Light-enhanced capacitance denucliding device: The prepared carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material is used as the negative electrode, the electrode using the carbon material as the active material is used as the positive electrode, and an externally applied visible light source and power supply are used.

[0043] Comparative Example Refer to Example 1, except that commercial activated carbon is used as the negative electrode active material.

[0044] In order to test the adsorption effect of the present invention on nuclide ions, adsorption experiments were carried out on the examples and control examples in different electrolyte systems, and corresponding performance tests were performed: System 1: Single nuclide ion solution, UO2 2+ 、Sr 2+ 、Cs + Set the concentration to 10ppm respectively; System 2: Different concentrations of UO2 2+ Single ion solution, concentration set to 1, 5, 20, 50, 100, 200 ppm; System 3: Mixed nuclide ion solution, UO2 2+ Set the concentration to 10ppm, K + , Na + , Ca 2+ , Mg 2+ The concentration of each ion was set to 500 ppm; Figure 7 The TiO prepared in Example 1 2-x The @C electrode treated the solution in System 1 under visible light and a voltage of 1.2V. The results showed that the removal rate exceeded 95%, demonstrating excellent photoelectrochemical removal. Combining photoadsorption and electroadsorption, it was found that visible light enhanced electroadsorption, indicating that the light-enhanced capacitive denucliding device has a stronger radionuclide purification effect than traditional capacitive adsorption and photoadsorption technologies.

[0045] Next, through an ion UO2 2+ The photoelectric adsorption effect of the present invention is described in detail, but it should be clearly pointed out that the electrode has a good effect on other ions (Sr 2+ 、Cs + ) has a similar effect.

[0046] Figure 8 The TiO prepared in Example 1 2-x The effect diagram of @C electrode treating adsorption system 1 solution at different voltages shows that the stronger the external electric field, the better the photoelectric adsorption effect.

[0047] Figure 9 The TiO prepared in Example 1 2-x@C electrode adsorption system two solution effect diagram at 1.2V. Even at a high concentration of 200ppm, the removal rate can still reach more than 80%.

[0048] Figure 10 The TiO prepared in Example 1 2-x @C electrode adsorption of UO2 in system 1 solution at different pH ranges at 1.2V 2 + The ion effect diagram shows the excellent radionuclide purification effect under a wide acid and alkali range.

[0049] Figure 11 The TiO prepared in Example 1 2-x @C electrode cycled for 10ppm UO2 at 1.2V 2+ Adsorption test diagram in solution. It can be seen from the figure that the electrode still maintains an ion removal rate of about 86% after 20 cycles, and the physical desorption can reach a desorption rate of more than 90%, showing the excellent cycle performance of the electrode.

[0050] Figure 12 The TiO prepared in Example 1 2-x The @C electrode was used cyclically to purify three solutions in the adsorption system at a voltage of 1.2 V, and the adsorption removal rate remained at around 96%, demonstrating the electrode's excellent anti-interference ion adsorption performance.

[0051] Figure 13 For the control example, 10ppm UO2 2+ The results of the electrosorption experiment in a single ion solution showed that the removal rate of radionuclides by the activated carbon electrode was about 30%, which was much lower than that of TiO 2-x @C.

[0052] From the comparison, it can be seen that compared with the activated carbon based on the double electric layer theory, the TiO 2-x @C is used as the negative electrode active material due to TiO 2-x @C has excellent hollow structure, photocatalytic performance and pseudocapacitive properties, showing high efficiency in radionuclide ion removal and has good application prospects.

[0053] The above photoelectric adsorption performance test results show that the present invention not only has a high photoelectric adsorption rate and selectivity for radionuclide ions, but also has good cyclic stability. Furthermore, the preparation method is simple, the process cost is low, and no secondary environmental pollution occurs, which shows broad development prospects.

[0054] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. A carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material, characterized in that: The active material is in the shape of nanotubes and consists of carbon-wrapped TiO2 hollow nanotubes. A large number of TiO2 nanosheets are present on the surface of the nanotubes.

2. A method for preparing the carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material according to claim 1, characterized in that The preparation method thereof comprises the following steps: S1. Preparation of TiO2 precursor: Add a titanium source to a mixed solvent of glycerol, ethanol, and ether, stir thoroughly for 30-60 minutes, transfer to a hydrothermal autoclave, and heat at 100-140°C for 12-36 hours. Centrifuge, wash, dry, and grind to obtain the TiO2 precursor. S2. Preparation of TiO 2-x @C: The TiO2 precursor prepared in step S1 is calcined in a crucible at 500-900℃ for 1-5h in a hydrogen / argon mixed gas environment with a heating rate of 5℃ / min to obtain TiO 2-x @C; S3, Capacitive deionization adsorption electrode material: Take the TiO obtained in step S2 2-x @C After adding N-methylpyrrolidone and grinding, Ketjen black and adhesive PVDF were added, among which TiO 2-x The weight ratio of @C, Ketjen black, and PVDF is 80:5:

5. After being ground evenly, they are coated on the current collector titanium mesh and dried to obtain a capacitive denuclearized photoelectrode.

3. The method for preparing the carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material according to claim 2, characterized in that: The titanium source in step S1 is one of titanyl sulfate, titanyl nitrate and titanyl chloride.

4. The method for preparing the carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material according to claim 2, characterized in that: The ratio of the hydrogen / argon mixture is 5:

95.

5. The method for preparing the carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material according to claim 2, characterized in that: The amount of the titanium source added in step S1 is 1-3 g; the total volume of the mixed solvent of glycerol, ethanol and diethyl ether is 50-100 mL, wherein the ratio of glycerol, ethanol and diethyl ether is 1:1-3:1, preferably the ratio of glycerol, ethanol and diethyl ether is 1:2:1; The amount of the TiO2 precursor added in step S2 is 0.4~0.6g.

6. A light-enhanced capacitive nuclide removal device made of the electrode material of claim 1, characterized in that The carbon-wrapped TiO2 hollow tube capacitor deionization adsorption electrode material prepared in claim 1 is used as the negative electrode, the electrode with carbon material as the active material is used as the positive electrode, and an externally applied visible light source and power supply are used.

7. An application of the light-enhanced capacitive nuclide removal device of claim 6 in nuclide purification, wherein the nuclide is one or a combination of two or more of uranyl, strontium, and cesium ions, present in the form of a solution, the concentration of the nuclide ions in the solution is 1-200 ppm, and the anions in the solution are one or a combination of two or more of chloride ions, nitrate ions, and sulfate ions; the voltages of the positive and negative electrodes are both 0.6-1.2 V, and the adsorbed positive and negative electrodes are regenerated by short-circuiting.

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