A carbon-coated TiO2 hollow tube capacitive deionization adsorption electrode material and its preparation method

Abstract

The application discloses a carbon-coated TiO2 hollow tube capacitive deionization adsorption electrode material and a preparation method. The active material is carbon-coated TiO2 hollow nanotube serving as an electrode. The TiO2 hollow nanotube is obtained by combining a hydrothermal reaction of a titanium precursor in an ethyl ether, ethanol and glycerol mixed solution system. The carbon-coated TiO2 hollow nanotube is prepared by a thermal reduction chemical method. The carbon-coated TiO2 hollow nanotube has abundant oxygen vacancies and excellent hollow nanotube structure, and can be effectively applied to the field of light-enhanced electric adsorption of nuclide ions. The carbon-coated TiO2 hollow tube capacitive deionization adsorption electrode material is assembled into a light-enhanced capacitive deionization device. Compared with a traditional carbon-based capacitive deionization device, the light-enhanced capacitive deionization device has better ion selectivity, stronger adsorption capacity of ions in water and higher cycle rate.

Description

Technical Field

[0001] This invention belongs to the field of nuclear pollution prevention and control, and in particular relates to a carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material and its preparation method. Background Technology

[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 nuclear energy processes, especially wastewater containing radionuclides such as uranium (U), cesium (Cs), and strontium (Sr), poses a significant potential threat to the natural environment and human health. The treatment and disposal of this wastewater has become a global focus. Traditional methods for removing radionuclides, such as physical adsorption, filtration, chemical precipitation, and bioremediation, while effective to some extent, typically face problems such as complex operation, high cost, unstable treatment results, and potential secondary pollution. How to safely, effectively, and economically remove radionuclides from wastewater remains a major challenge that urgently needs to be addressed.

[0003] Capacitive deionization (CDI) technology is an emerging water treatment technology with advantages such as high efficiency, energy saving, and environmental friendliness. Existing CDI technologies use carbon-based electrodes to adsorb ions in water using the electric double layer effect. However, due to the poor ion adsorption 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] To address the shortcomings of existing technologies, this invention provides a carbon-encapsulated TiO2 hollow tube capacitive deionization adsorption electrode material and its preparation method. This material utilizes carbon-encapsulated oxygen-rich vacancy TiO2 hollow nanotubes (TiO2... 2-x @C) was used as the active material for the photoelectrode, and then a capacitive adsorption photoelectrode was prepared. A photo-enhanced capacitive nuclide removal device was assembled using this electrode, which, compared with the traditional carbon-based capacitive nuclide removal device, has better ion selectivity, stronger ability to adsorb ions in water, and higher circulation rate.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material. The active material is in the form of nanotubes and is composed of carbon-coated TiO2 hollow nanotubes. The surface of the nanotubes has a large number of TiO2 nanosheets.

[0007] This invention also provides a method for preparing a carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material, comprising the following steps:

[0008] S1. Preparation of TiO2 precursor: Add the titanium source to a mixed solvent of glycerol, ethanol and diethyl ether, stir thoroughly for 30-60 min, then transfer to a hydrothermal reactor and keep at 100-140℃ for 12-36 h. After centrifugation, washing, drying and grinding are performed to obtain the TiO2 precursor.

[0009] S2, Preparation of TiO 2-x @C: The TiO2 precursor prepared in step S1 was calcined in a crucible at 500-900℃ for 1-5 hours in a hydrogen / argon mixed gas environment, with a heating rate of 5℃ / min, finally yielding TiO2. 2-x @C;

[0010] S3, Capacitive deionization adsorption electrode material: Take the TiO2 obtained in step S2. 2-x @C is added to N-methylpyrrolidone and ground, then Ketjen Black and PVDF adhesive are added, wherein TiO2 is present. 2-x The weight ratio of C, Ketjen Black, and PVDF is 80:5:5. After grinding evenly, the mixture is coated onto a current collector titanium mesh and dried to obtain a capacitor denuclearized photoelectrode.

[0011] This is a further optimization of a method for preparing a carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material.

[0012] Preferably, the titanium source mentioned in step S1 is one of titanium oxysulfate, titanium oxynitrate, and titanium oxychloride.

[0013] Preferably, the hydrogen / argon mixing ratio in step S2 is 5:95.

[0014] Preferably, the amount of titanium source added in step S1 is 1~3g, and the total volume of the mixed solvent of glycerol, ethanol and diethyl ether is 50~100mL, 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.

[0015] The amount of TiO2 precursor added in step S2 is 0.4~0.6g.

[0016] This invention also provides a photo-enhanced capacitor denucleation device.

[0017] The device uses a carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material as the negative electrode and a carbon material as the active material as the positive electrode, with an externally applied visible light source and power supply.

[0018] This invention also provides an application of a photo-enhanced capacitive nuclide removal device in nuclide purification. The nuclide is one or a combination of two or more of uranyl, strontium, and cesium ions, present in solution with a nuclide ion concentration of 1-200 ppm. The anions in the solution are one or a combination of two or more of chloride, nitrate, and sulfate ions. The voltage of both the positive and negative electrodes is 0.6-1.2 V. Regeneration of the adsorbed positive and negative electrodes is achieved by short-circuiting.

[0019] The advantages of this invention compared to the prior art are as follows:

[0020] (1) Compared with traditional carbon-based capacitor denuclearization devices, the photo-enhanced capacitor denuclearization device provided by the present invention has better ion selectivity, stronger ability to adsorb ions in water, and higher circulation rate.

[0021] (2) The photo-enhanced capacitive denitrification device provided by this invention is simple to operate during electroadsorption. It can efficiently remove nuclide ions from water simply by combining an external visible light source with traditional capacitive adsorption technology. In a preferred embodiment, TiO₂ is obtained by mixing glycerol, ethanol, and diethyl ether in a volume ratio of 1:2:1. 2-x @C electrode, better effect, with superior adsorption capacity.

[0022] (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 sites for nuclide adsorption. This invention combines visible light source irradiation of the back of the current collector to excite the active sites at the bottom of the current collector, thereby enhancing the adsorption activity of nuclides. Simultaneously, the active material of this invention is a carbon-encapsulated hollow titanium dioxide hollow nanotube composite electrode (TiO2). 2-x @C exhibits excellent photocatalytic activity, and its abundant oxygen vacancies and customized hollow structure accelerate electron transport, making it effective for electroadsorption removal of nuclide ions. Attached Figure Description

[0023] Figure 1 Schematic diagram of a photo-enhanced capacitive denuclearization device for implementing nuclide adsorption;

[0024] Figure 2 TiO2 prepared in Example 1 2-x XRD pattern of @C;

[0025] Figure 3 TiO2 prepared in Example 1 2-x SEM image of @C;

[0026] Figure 4 TiO2 prepared in Example 1 2-x TEM image of @C;

[0027] Figure 5TiO2 prepared in Example 1 2-x XPS plot of @C, Figure (a) captures Ti derived from hydrogen reduction. 3+ The trajectory (b) captures the empty space at position O;

[0028] Figure 6 TiO2 prepared in Example 2 2-x TEM image of @C;

[0029] Figure 7 TiO2 prepared in Example 1 2-x The C electrode was used to treat the solution of system one under visible light and a voltage of 1.2V;

[0030] Figure 8 TiO2 prepared in Example 1 2-x @C electrode treatment effect of adsorption system one solution at different voltages;

[0031] Figure 9 TiO2 prepared in Example 1 2-x The effect of the C electrode on the adsorption system of two solutions at 1.2V;

[0032] Figure 10 TiO2 prepared in Example 1 2-x @C electrode adsorbs UO2 in solution at different pH ranges under 1.2V 2 + Effect diagram of ions;

[0033] Figure 11 TiO2 prepared in Example 1 2-x @C electrode cycling is used at 1.2V in 10ppm UO2 2+ Adsorption test diagram in solution;

[0034] Figure 12 TiO2 prepared in Example 1 2-x @C electrode circulation is used to purify the three solutions of the adsorption system at a voltage of 1.2V;

[0035] Figure 13 As a control example, at 10 ppm UO2 2+ Electroadsorption experiments in single-ion solutions. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] The present invention will now be described through specific embodiments and comparative examples. Example 1

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

[0039] Preparation method:

[0040] S1. Preparation of TiO2 precursor: 2g of titanium oxysulfate was added to a mixed solvent of glycerol, ethanol, and diethyl ether in a ratio of 1:3:1. After stirring thoroughly for 40min, the mixture was transferred to a hydrothermal reactor and heated in an oven at 120℃ for 24h. Afterwards, the mixture was centrifuged, washed, dried, and ground to obtain the TiO2 precursor.

[0041] S2, Preparation of TiO 2-x @C: Take 0.5g of TiO2 precursor in a crucible and calcine it at 700℃ for 3h in a hydrogen / argon mixed gas environment (hydrogen:argon = 5:95) with a heating rate of 5℃ / min. TiO2 is then obtained. 2-x @C;

[0042] S3. Preparation of capacitive adsorption photoelectrode: Take TiO2 2-x @C is added to N-methylpyrrolidone and ground, then Ketjen Black and PVDF adhesive are added, wherein TiO2 is present. 2-x The weight ratio of C, Ketjen Black, and PVDF is 80:5:5. After grinding evenly, the mixture is coated onto a current collector titanium mesh and dried to obtain a capacitor denuclearized photoelectrode.

[0043] S4. Using the photoelectric electrode obtained in step S3 as the negative electrode and the electrode with carbon material as the active material as the positive electrode, a photo-enhanced capacitor denuclearization device is formed. This device is used to perform photoelectric adsorption of nuclide ions.

[0044] A carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material was prepared by the above method.

[0045] Photo-enhanced capacitor denuclearization device:

[0046] The carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material is used as the negative electrode, and the electrode with carbon material as the active material is used as the positive electrode. The externally applied visible light source and power supply are used.

[0047] TiO2 prepared in Example 1 2-x @C conducted relevant measurements, and the results are attached. Figure 2-5 .

[0048] Figure 2 TiO2 prepared in Example 1 2-xThe XRD pattern of @C shows that its diffraction peaks are consistent with those of the standard cards JCPDS 21-1276 and 21-1262, thus confirming the successful synthesis of TiO2.

[0049] Figure 3 TiO2 prepared in Example 1 2-x The SEM and TEM images of @C show that TiO2 2-x The material synthesized by @C has a hollow nanotube morphology and a large number of nanosheets on its surface.

[0050] Figure 4 TiO2 prepared in Example 1 2-x The TEM image of @C shows TiO₂. 2-x The material synthesized by @C has a hollow structure and a large number of nanosheets on its surface.

[0051] Figure 5 TiO2 prepared in Example 1 2-x The XPS graph for @C shows that Ti... 3+ (b) Defects, capturing abundant oxygen vacancies. Example 2

[0052] Referring to Example 1, the difference lies in: TiO2 in step S2 2-x In the preparation of @C, the ratio of glycerol, ethanol and diethyl ether is 1:1:1.

[0053] The TiO2 prepared in Example 2 2-x @C conducted relevant measurements, and the results are attached. Figure 6 The nanosheets on the surface are significantly rougher and denser. Example 3

[0054] This embodiment provides a carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material, its preparation method, and a photo-enhanced capacitor denuclearization device.

[0055] Preparation method:

[0056] S1. Preparation of TiO2 precursor: 1g of titanium oxynitrate was added to 50mL of a mixed solvent of glycerol, ethanol, and diethyl ether in a ratio of 1:2:1. After stirring thoroughly for 30min, the mixture was transferred to a hydrothermal reactor and hydrothermally heated at 100℃ for 12h in an oven. Afterwards, the mixture was centrifuged, washed, dried, and ground to obtain the TiO2 precursor.

[0057] S2, Preparation of TiO 2-x@C: Take 0.4g of TiO2 precursor in a crucible and calcine it at 500℃ for 1h in a hydrogen / argon mixed gas environment (hydrogen:argon = 5:95) with a heating rate of 5℃ / min. TiO2 is then obtained. 2-x @C;

[0058] S3. Preparation of capacitive adsorption photoelectrode: Take TiO2 2-x @C is added to N-methylpyrrolidone and ground, then Ketjen Black and PVDF adhesive are added, wherein TiO2 is present. 2-x The weight ratio of C, Ketjen Black, and PVDF is 80:5:5. After grinding evenly, the mixture is coated onto a current collector titanium mesh and dried to obtain a capacitor denuclearized photoelectrode.

[0059] S4. Using the photoelectric electrode obtained in step S3 as the negative electrode and the electrode with carbon material as the active material as the positive electrode, a photo-enhanced capacitor denuclearization device is formed. This device is used to perform photoelectric adsorption of nuclide ions.

[0060] A carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material was prepared by the above method.

[0061] Photo-enhanced capacitor denuclearization device:

[0062] The carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material is used as the negative electrode, and the electrode with carbon material as the active material is used as the positive electrode. The externally applied visible light source and power supply are used. Example 4

[0063] This embodiment provides a carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material, its preparation method, and a photo-enhanced capacitor denuclearization device.

[0064] Preparation method:

[0065] S1. Preparation of TiO2 precursor: 3g of titanium oxychloride was added to 100mL of a mixed solvent of glycerol, ethanol, and diethyl ether in a ratio of 1:2:1. After stirring thoroughly for 60min, the mixture was transferred to a hydrothermal reactor and heated in an oven at 140℃ for 36h. Afterwards, the mixture was centrifuged, washed, dried, and ground to obtain the TiO2 precursor.

[0066] S2, Preparation of TiO 2-x @C: Take 0.6g of TiO2 precursor in a crucible and calcine it at 900℃ for 5h in a hydrogen / argon mixed gas environment (hydrogen:argon = 5:95), with a heating rate of 5℃ / min, to finally obtain TiO2. 2-x @C;

[0067] S3. Preparation of capacitive adsorption photoelectrode: Take TiO2 2-x@C is added to N-methylpyrrolidone and ground, then Ketjen Black and PVDF adhesive are added, wherein TiO2 is present. 2-x The weight ratio of C, Ketjen Black, and PVDF is 80:5:5. After grinding evenly, the mixture is coated onto a current collector titanium mesh and dried to obtain a capacitor denuclearized photoelectrode.

[0068] S4. Using the photoelectric electrode obtained in step S3 as the negative electrode and the electrode with carbon material as the active material as the positive electrode, a photo-enhanced capacitor denuclearization device is formed. This device is used to perform photoelectric adsorption of nuclide ions.

[0069] A carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material was prepared by the above method.

[0070] Photo-enhanced capacitor denuclearization device:

[0071] The carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material is used as the negative electrode, and the electrode with carbon material as the active material is used as the positive electrode. The externally applied visible light source and power supply are used.

[0072] Comparative Example

[0073] Referring to Example 1, the difference is that commercial activated carbon is used as the negative electrode active material.

[0074] To test the adsorption effect of the present invention on nuclide ions, adsorption experiments were conducted on the examples and control examples in different electrolyte systems, and corresponding performance tests were performed:

[0075] System 1: Single nuclide ion solution, UO2 2+ 、Sr 2+ Cs + The concentration was set to 10 ppm.

[0076] System 2: UO2 of different concentrations 2+ Single ion solutions with concentrations set at 1, 5, 20, 50, 100, and 200 ppm;

[0077] System 3: Mixed nuclide ion solution, UO2 2+ The concentration was set to 10 ppm, K + Na + Ca 2+ Mg 2+ The concentration of each ion was set at 500 ppm;

[0078] Figure 7 TiO2 prepared in Example 1 2-xThe C electrode was used to treat the solution of System 1 under visible light and a voltage of 1.2V. The results showed that the removal rate was above 95%, demonstrating excellent photoelectrochemical removal efficiency. Combining photoadsorption and electroadsorption, it was found that visible light enhances electroadsorption, indicating that the photo-enhanced capacitive denitrification device has a stronger denitrification effect than traditional capacitive adsorption and photoadsorption technologies.

[0079] Below, through an ionic UO2 2+ The photoelectric adsorption effect of the present invention will be described in detail, but it should be clearly stated that the electrode is effective against other ions (Sr). 2+ Cs + The effect is similar.

[0080] Figure 8 TiO2 prepared in Example 1 2-x The graphs show the effect of the @C electrode treating the adsorption system solution under different voltages, indicating that the stronger the applied electric field, the better the photoelectric adsorption effect.

[0081] Figure 9 TiO2 prepared in Example 1 2-x The effect of the @C electrode on the two solutions in the 1.2V adsorption system shows that even at a high concentration of 200ppm, the removal rate can still reach more than 80%.

[0082] Figure 10 TiO2 prepared in Example 1 2-x @C electrode adsorbs UO2 in solution at different pH ranges under 1.2V 2 + The ion effect diagram demonstrates excellent radionuclide purification performance across a wide acid-base range.

[0083] Figure 11 TiO2 prepared in Example 1 2-x @C electrode cycling is used at 1.2V in 10ppm UO2 2+ The adsorption test graph in the solution shows 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%, demonstrating the excellent cycling performance of the electrode.

[0084] Figure 12 TiO2 prepared in Example 1 2-x The @C electrode was used in a cycle to purify the three solutions of the adsorption system at a voltage of 1.2V, and the adsorption removal rate remained at around 96%, demonstrating the electrode's excellent anti-interference ion adsorption performance.

[0085] Figure 13 As a control example, at 10 ppm UO2 2+Electroadsorption experiments in single-ion solutions showed that the removal rate of nuclides by photoelectric adsorption using an activated carbon electrode was around 30%, far lower than that of TiO₂. 2-x @C.

[0086] As can be seen from the comparison, compared with activated carbon based on the double-layer theory, the present invention uses TiO2. 2-x @C is used as the negative electrode active material, because TiO 2-x @C possesses excellent hollow structure, photocatalytic performance, and pseudocapacitive properties, exhibiting high efficiency in the removal of nuclide ions and showing promising application prospects.

[0087] The above photoelectric adsorption performance test results show that this invention not only has a high photoelectric adsorption rate and selectivity for nuclide ions, but also possesses good cycle stability. Furthermore, the preparation method is simple, the process cost is low, and it does not cause secondary environmental pollution, thus possessing broad development prospects.

[0088] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A method for preparing a carbon-coated TiO2 hollow tube capacitive deionization adsorption electrode material, characterized in that... A preparation method thereof, comprising the following steps: S1, preparing TiO2 precursor: adding titanium source into mixed solvents of glycerol, ethanol and diethyl ether, stirring for 30-60 min, then transferring to a hydrothermal kettle, keeping at 100-140 DEG C for 12-36 h, then centrifuging, washing, drying and grinding to obtain TiO2 precursor; S2, preparing TiO 2-x @C: The TiO2 precursor prepared in step S1 is calcined in a crucible in a hydrogen / argon mixed gas environment at 500-900°C for 1-5h, with a temperature rising speed of 5°C / min, and finally TiO 2-x @C; S3, preparing a capacitive deionization electrode material: taking the TiO 2-x @C, after adding N-methyl pyrrolidone grinding, adding ketchen black and adhesive PVDF, wherein the weight ratio of TiO 2-x @C, the weight ratio of ketchen black, PVDF is 80:5:5, after grinding evenly, coating on the current collector titanium net, drying, obtaining the prepared capacitive deionization electrode material; The TiO 2-x @C is in the form of nanotubes, consisting of carbon-coated TiO2 hollow nanotubes, and a large number of TiO2 nanosheets exist on the surface of the nanotubes.

2. The preparation method of carbon-coated TiO2 hollow tube capacitive deionization adsorption electrode material according to claim 1, characterized in that, The titanium source in step S1 is one of titanyl sulfate, titanyl nitrate and titanyl chloride.

3. The preparation method of the carbon-coated TiO2 hollow tube capacitive deionization adsorption electrode material according to claim 1, characterized in that, The ratio of hydrogen / argon gas mixture is 5:

95.

4. The method according to claim 1, wherein the method is characterized by, The adding amount of the titanium source in step S1 is 1-3 g; the total volume of the mixed solvents of glycerol, ethanol and diethyl ether is 50-100 mL, wherein the ratio of glycerol, ethanol and diethyl ether is 1:1-3:1; The adding amount of the TiO2 precursor in step S2 is 0.4-0.6 g.

5. A photo-enhanced capacitive decontamination device made from the electrode material of claim 1, characterized by The carbon-coated TiO2 hollow tube capacitor deionization adsorption electrode material prepared in claim 1 is used as a negative electrode, and an electrode with carbon material as active material is used as a positive electrode, and an external visible light source and a power supply are applied.

6. The application of the light-enhanced capacitor deionization device in claim 5 in nuclide purification, wherein the nuclide is one or a combination of two or more of uranyl, strontium and cesium ions, and exists in the form of solution, the concentration of 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 voltage of the positive electrode and the negative electrode is 0.6-1.2 V, and the positive electrode and the negative electrode after adsorption are short-circuited to realize regeneration.

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