Electrode material for amine liquid purification and preparation method thereof

Abstract

The application provides an electrode material for amine liquid purification and a preparation method thereof, relates to the technical field of organic amine liquid desulfurization, and prepares a silver-silicon-carbon nanotube-nano titanium dioxide composite hybrid electrode material with strong electric adsorption capacity through a sol-gel method combined with a chemical reduction method, and removes heat stable salts from amine liquid by means of an electric field adsorption separation technology. The specific surface area of the desulfurization amine liquid adsorption composite electrode material is large (about 82 m 2 ·g ‑1 ) and the specific capacitance is high (about 132 F·g ‑1 ), the amine liquid can be effectively contacted, the adsorption rate is high, the pore volume is large, the space for adsorbing and storing ions is large, the adsorption effect is good, the removal rate of heat stable salts can reach more than 90%, meanwhile, the stability is high, the resorption is strong, the adsorption capacity can still reach about 90% of the initial value after 24 hours of circulation, and in addition, the technology has the advantages of simple operation, low maintenance cost and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of organic amine liquid desulfurization technology, specifically to an electrode material for amine liquid purification and its preparation method. Background Technology

[0002] Hydrogen sulfide and carbon dioxide are undesirable impurities in natural gas. To eliminate these acidic gases, both oil and natural gas must undergo desulfurization treatment. The media commonly used in natural gas desulfurization units to absorb acidic gases are mainly organic amine solvents, such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), and methyldiethanolamine (MDEA). MDEA, in particular, has advantages such as strong absorption capacity for acidic gases, low corrosiveness, high chemical stability, and low heat of reaction with acidic gases, effectively reducing reboiler load and thus lowering operating costs. These advantages have led to its widespread use in desulfurization systems.

[0003] However, during the desulfurization process, the amine solution continuously absorbs acidic gases such as hydrogen sulfide and carbon dioxide, causing the amine to undergo a protonation reaction. When this protonation reaction occurs with thermally degraded components of the amine (such as formate, oxalate, acetate, glycolate, and thiosulfate), thermally stable salts are formed. These salts accumulate in the solution, eventually leading to a decrease in the quality and ineffectiveness of the amine solvent, thus affecting the safe and efficient production of natural gas. Therefore, eliminating or reducing thermally stable salts from the amine solution is a highly challenging issue for the oil and gas desulfurization industry. Over the past few decades, many researchers have explored various technologies to remove heat-stable salts from amine solutions, such as ion exchange methods (US Patent US5788864 and Chinese Patents CN1861762A, CN1733355A, etc.), vacuum distillation and electrodialysis (US Patent US005910611A and Chinese Patents CN100441276C, CN104192946A, CN1844460, etc.), and electroadsorption (CN111097224A). Ion exchange is currently a commonly used method for removing heat-stable salts in the natural gas and oil industries. However, ion exchange resins are expensive and generate large amounts of liquid and solid waste that require treatment. Furthermore, while vacuum distillation and electrodialysis can also be used to remove heat-stable salts, they are not cost-effective due to the high energy and water consumption, the significant waste generated, and the potential for phase transitions during distillation. Electrodesorption is a promising technology, but current electrode materials used for amine solutions suffer from serious problems such as limited variety, poor stability, low efficiency, and poor reusability. These issues have prompted the search for more efficient and environmentally friendly methods and materials to remove heat-stable salts from desulfurized amine solution systems. Summary of the Invention

[0004] To overcome the shortcomings and deficiencies of existing technologies, this invention provides an environmentally friendly electrode material and its preparation method suitable for the removal of heat-stable salts by electric field adsorption in petroleum and natural gas desulfurization amine liquid systems. This technology prepares a silver-silicon-carbon nanotube-nanotitanium dioxide composite hybrid electrode material with strong electroadsorption capacity through a sol-gel method combined with chemical reduction, and successfully removes heat-stable salts from the amine liquid using electric field adsorption separation technology. This separation method has the advantages of high efficiency, simple operation, low maintenance cost, and environmental friendliness. In particular, this novel desulfurization amine liquid adsorption composite electrode material has characteristics such as large specific surface area, specific capacitance, strong adsorption capacity, and strong reabsorption capacity. This technology is a potential technology for the purification and regeneration of desulfurization amine liquid.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a method for preparing an electrode material, comprising the following steps:

[0007] (1) Acidification treatment of carbon nanotubes: Immerse carbon nanotubes in an acidic solution, heat and reflux or sonicate the carbon nanotubes, dilute with water, let stand, filter and wash, and dry the product to obtain acidified carbon nanotubes.

[0008] (2) Add acidified carbon nanotubes and organosiloxanes to an ethanol aqueous solution, react in a constant temperature water bath, cool to room temperature, filter and wash, and dry the product to obtain modified carbon nanotubes.

[0009] (3) Preparation of carbon nanotube silica sol: Modified carbon nanotubes are mixed with toluene and then subjected to hydrolysis and condensation reaction to obtain carbon nanotube sol solution.

[0010] (4) Introduction of silver active sites: Silver nitrate solution was added to carbon nanotube silica sol solution, and silver-silicon-carbon nanotube hybrid material was synthesized by chemical reduction with hydrazine hydrate.

[0011] (5) Nano-titanium dioxide composite: Tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed and stirred evenly. The mixture of anhydrous ethanol and water is slowly dripped in and stirred continuously. The mixture is allowed to stand for aging to obtain titanium dioxide gel. The titanium dioxide gel is mixed with the silver-silicon-carbon nanotube hybrid material in step (4), stirred evenly, dried and cooled to obtain the silver-silicon-carbon nanotube-nano-titanium dioxide composite hybrid electrode material.

[0012] Furthermore, the acidic solution mentioned in step (1) is concentrated sulfuric acid and nitric acid.

[0013] Furthermore, the concentrated sulfuric acid has a mass concentration of 98%, and the nitric acid has a mass concentration of 68%.

[0014] Furthermore, the volume ratio of concentrated sulfuric acid to nitric acid is 2:1 to 4:1.

[0015] Further, in step (1), the temperature of the heating reflux is 90-120℃; the time of the heating reflux or ultrasonic treatment is 3-8h; the time of the standing is 6-12h; and the temperature of the drying is 60-80℃ and the time is 8-12h.

[0016] Further, the organosiloxane mentioned in step (2) includes one or more of KH560, KH550, and KH690.

[0017] Furthermore, the molar ratio of carbon nanotubes and organosiloxanes in step (2) is 3:1-9:1.

[0018] Furthermore, the temperature of the constant temperature water bath in step (2) is 60-80℃ and the time is 6-12h; the drying is carried out in a vacuum drying oven at 60-80℃ for 8-12h.

[0019] Furthermore, the hydrolysis and condensation reaction in step (3) is carried out at a temperature of 80-100℃ for 18-24 hours.

[0020] The present invention also provides electrode materials prepared by the above-described preparation method.

[0021] In some specific embodiments, the preparation of the electrode material includes the following steps:

[0022] (1) Acidification treatment of carbon nanotubes: Carbon nanotubes are immersed in an acidic solution composed of concentrated sulfuric acid (98% by mass) and nitric acid (68% by mass), with the ratio of concentrated sulfuric acid to nitric acid controlled in the range of 2:1-4:1. The carbon nanotubes are heated under reflux or sonicated at 90-120℃ for 3-8 hours. Then the system is diluted with deionized water and allowed to stand for 6-12 hours. After standing and separating, the layers are washed by deionized water filtration. The product is dried in a vacuum drying oven at 60-80℃ for 8-12 hours to achieve purification and carboxyl functionalization of nanotubes. This process is achieved by utilizing the strong oxidizing properties of strong acid.

[0023] (2) Siloxane modification of acidified carbon nanotube surface: Acidified carbon nanotubes are added to an aqueous ethanol solution along with one or more organosiloxanes such as KH560, KH550, and KH690, ensuring the molar ratio of carbon nanotubes to silanes is controlled at 3:1-9:1. The reaction is carried out in a constant temperature water bath at 60-80℃ for 6-12 hours, cooled to room temperature, filtered and washed, and the product is dried in a vacuum drying oven at 60-80℃ for 8-12 hours to complete the siloxane modification. The connection between carbon nanotubes and organosilanes is achieved through the formation of COC covalent bonds, which result from the nucleophilic substitution reaction between the carboxyl groups of acidified carbon nanotubes and the epoxy groups of siloxanes, leading to the ring-opening reaction of the epoxy groups.

[0024] (3) Preparation of carbon nanotube silica sol: These siloxane-functionalized carbon nanotubes were mixed with toluene and treated at 80-100℃ for 18-24 h by hydrolysis and condensation reactions to form a sol solution with an interconnected, uniform, porous, and ordered network structure. The alkoxy groups in the organosilanes were hydrolyzed sequentially to generate silanol groups, which then underwent condensation reactions between silanols, thereby forming a self-assembled Si-O-Si network on the surface of the carbon nanotubes.

[0025] (4) Introduction of silver active sites: Silver nitrate solution was added to the above-mentioned carbon nanotube silica sol solution, and then chemically reduced with hydrazine hydrate to synthesize a silver-silicon-carbon nanotube hybrid material. By forming strong coordination bonds between the Si-O-Si network and the silver nanoparticles, the successful incorporation of silver nanoparticles into the siloxane-modified carbon nanotube surface is ensured, thereby preventing the leaching of silver nanoparticles. The hybrid material was thoroughly washed with deionized water to remove unreacted substances, and then dried in an oven at a controlled temperature of 90-180℃.

[0026] (5) Nano-titanium dioxide composite: Tetrabutyl titanate, glacial acetic acid, and anhydrous ethanol are mixed in a volume ratio of 1:1:2 and stirred mechanically or electromagnetically until homogeneous. Then, under rapid stirring, anhydrous ethanol and deionized water are slowly added dropwise in a volume ratio of 1:1 (pH controlled at 2-3, adjusted with hydrochloric acid or nitric acid solution). The temperature is controlled at 25℃-30℃, and stirring is continued for 2-3 hours. The mixture is then allowed to stand for 2-4 hours to complete the preparation of the titanium dioxide gel. The titanium dioxide gel is then mixed with the hybrid material in which silver active sites were successfully introduced in step (4), stirred until homogeneous, and then dried in an oven at a temperature controlled at 100-120℃ for 3-4 hours. Finally, it is cooled to room temperature to complete the entire preparation process of the silver-silicon-carbon nanotube-nano-titanium dioxide composite hybrid electrode material. The composite of nano-titanium dioxide can further improve the electroadsorption capacity.

[0027] Ultimately, the self-assembled, interconnected porous siloxane network structure was prepared, which could tightly surround carbon nanotubes and titanium dioxide nanoparticles containing silver nanoparticles, resulting in an ordered silver-silicon-carbon nanotube-nano titanium dioxide composite mesoporous material. This material contains a large number of mesopores, which makes it easy for ions to enter the inner pores and effectively improves the adsorption capacity.

[0028] The present invention also provides a method for preparing an electrode, comprising the following steps:

[0029] S1: Electrode slurry preparation: The electrode material described in claim 8, carbon black, polyvinylidene fluoride powder and polytetrafluoroethylene powder are mixed, and then mixed with N-methylpyrrolidone solvent and stirred to obtain a mixed slurry;

[0030] S2: Electrode plate pressing: The mixed slurry is coated onto foamed nickel or foamed tin, placed under vacuum conditions, and pressed to obtain the final product.

[0031] Physically connecting the electrode material to the amine liquid electroadsorption device enables electrode plate connection.

[0032] The present invention also provides an electrode prepared by the above-described preparation method.

[0033] In some specific embodiments, the preparation of the electrode includes the following steps:

[0034] S1: Electrode slurry preparation: Mix silver-silicon-carbon nanotube-nano titanium dioxide composite hybrid electrode material (60%-80%), carbon black (10-30%), polyvinylidene fluoride powder (8-9%) and polytetrafluoroethylene powder (1-2%), then mix with N-methylpyrrolidone solvent, and stir mechanically or magnetically for 2-3 hours to form a uniform thick slurry.

[0035] S2: Electrode plate pressing: The mixed slurry is coated onto foamed nickel or foamed tin and placed in a vacuum oven at 70℃-100℃ for 18-26 hours to eliminate N-methylpyrrolidone solvent. Then, the foamed nickel or foamed tin is pressed at 10-20MPa to improve solvent quality.

[0036] S3: Electrode plate electrical connection: Physically electrically connect the electrode material to the amine liquid electroadsorption device.

[0037] Furthermore, the present invention also provides an electroadsorption device and process including the above-described electrodes.

[0038] 1) Composition of the electroadsorption device

[0039] A schematic diagram of the invented electroadsorption device is shown in Figure 1. The device mainly comprises a silver-silicon-carbon nanotube-nanotitanium dioxide composite hybrid electrode plate, an electroadsorption tank, an organic amine solution container, two peristaltic pumps, and a DC regulated power supply. The core of the electroadsorption device is the electroadsorption module, and the core of the electroadsorption module is the composite electrode developed in this invention. The electrode plates are evenly and symmetrically distributed parallel to each other along the long side of the electroadsorption tank on both sides, with one side serving as the positive electrode and the other as the negative electrode. All electrode plates on each side are connected to the positive or negative terminal of the DC power supply via current collector wires. The size of the electrodes is determined according to the size of the electroadsorption tank and the amine solution processing volume. The electroadsorption tank is assembled using fiberglass or plexiglass plates capable of withstanding a certain pressure. The size of the tank is determined according to the amount of amine solution being processed. An inlet and outlet for the amine solution are respectively set on the two sides of the wide side of the tank to ensure smooth circulation of the organic amine solution. These two outlets are connected to the peristaltic pumps. The selection of the peristaltic pumps should be based on the amine solution processing volume.

[0040] 2) Process flow and control

[0041] ① Apply a suitable voltage (0.5-1.2V) to the electrode plates on both sides of the adsorption tank using a DC regulated power supply. ② Pump the organic amine solution into the electro-adsorption tank from the inlet, replenishing the amine solution to a certain liquid level, and then continuously circulate it through the outlet of the electro-adsorption tank at a certain flow rate. ③ The organic amine solution passing through the outlet of the electro-adsorption tank is then pumped back into the organic amine solution tank by another peristaltic pump, and this cycle is repeated. ④ Periodically remove the treated amine solution from the sampling port and use a UV-Vis spectrophotometer to assess the concentration of the heat-stable salt in the MDEA solution. ⑤ Clean and replace the composite electrode periodically.

[0042] The technical effects achieved by this invention are:

[0043] This invention provides an environmentally friendly material and method for removing heat-stable salts in petroleum and natural gas desulfurization amine liquid systems. Compared with current ion exchange methods, vacuum distillation, and electrodialysis, this method (1) has low pollution, low energy consumption, high utilization rate, is environmentally friendly, and produces no byproducts; (2) the processing is simple and easy to control; and (3) it can separate heat-stable salt substances with low content that are difficult to separate by conventional methods. The key to this method is the developed silver-silicon-carbon nanotube-nanotitanium dioxide composite hybrid electrode material. This material has not been reported in any patents, literature, or data. The specific surface area of ​​this desulfurization amine liquid adsorption composite electrode material is large (~82m²). 2 ·g -1 and a relatively high specific capacitance (~132 F·g) -1This technology effectively contacts organic amine solutions, exhibiting a high adsorption rate. Its large pore volume provides ample space for ion adsorption and storage, resulting in excellent adsorption performance and a removal rate of over 90% for heat-stable salts. It also boasts high stability and strong reabsorption capacity, maintaining nearly 90% of its initial adsorption capacity after 24 hours of cycling. Furthermore, it possesses good conductivity and high selectivity. Based on these advantages, this technology is a promising approach for removing heat-stable salts from organic amine solutions, and its application will effectively maintain the efficiency of organic amine solutions in absorbing acidic gases in natural gas desulfurization units. Attached Figure Description

[0044] Figure 1 This is a simplified diagram of the device and process flow for removing heat-stable salts from desulfurized organic amine solutions according to the present invention.

[0045] Among them, 1-peristaltic pump, 2-desulfurized amine liquid tank, 3-DC regulated power supply, 4-electrode attachment tank, 5-current collector, 6-sampling port; 7-silver-silicon-carbon nanotube-nano titanium dioxide composite hybrid electrode plate. Detailed Implementation

[0046] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0047] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention.

[0048] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0049] It is worth noting that the raw materials used in this invention are all commercially available products, and therefore their sources are not specifically limited.

[0050] Example 1

[0051] 1. Preparation of composite electrode materials

[0052] (1) Acidification treatment of carbon nanotubes: Carbon nanotubes are immersed in an acidic solution composed of concentrated sulfuric acid (98% by mass) and nitric acid (68% by mass), with the ratio of concentrated sulfuric acid to nitric acid controlled at 2:1. The carbon nanotubes are heated and refluxed or sonicated at 100°C for 6 hours. Then the system is diluted with deionized water and allowed to stand for 12 hours. After standing and separating, the layers are washed by deionized water filtration. The product is dried in a vacuum drying oven at 80°C for 8 hours.

[0053] (2) Siloxane modification of acidified carbon nanotube surface: acidified carbon nanotube and KH560 organosiloxane were added to an aqueous ethanol solution. The molar ratio of carbon nanotube and silane was controlled at 4:1. The reaction was carried out in a constant temperature water bath at 80°C for 6 hours. After cooling to room temperature, the product was filtered and washed. The product was dried in a vacuum drying oven at 80°C for 8 hours to complete the siloxane modification.

[0054] (3) Preparation of carbon nanotube silica sol: The above siloxane-functionalized carbon nanotubes were mixed with toluene and treated with hydrolysis and condensation reaction at 90°C for 18 h to prepare sol solution.

[0055] (4) Introduction of silver active sites: Silver nitrate solution was added to the above carbon nanotube silica sol solution, and then chemically reduced by hydrazine hydrate to synthesize silver-silicon-carbon nanotube hybrid material. The hybrid material was thoroughly washed with deionized water to remove unreacted substances, and then dried in an oven at a controlled temperature of 120°C.

[0056] (5) Nano-titanium dioxide composite: Tetrabutyl titanate, glacial acetic acid, and anhydrous ethanol were mixed in a volume ratio of 1:1:2 and stirred mechanically or electromagnetically until homogeneous. Then, under rapid stirring, anhydrous ethanol and deionized water were mixed in a volume ratio of 1:1. The pH value was adjusted to 2.4 with nitric acid solution and added dropwise slowly. The temperature was controlled at 25°C, and the mixture was stirred continuously for 3 hours. After standing and aging for 4 hours, the titanium dioxide gel was completed. The titanium dioxide gel was mixed with the hybrid material in which silver active sites were successfully introduced in step (4), stirred until homogeneous, and then dried in an oven at 120°C for 3 hours. After drying, the mixture was cooled to room temperature.

[0057] 2. Electrode preparation

[0058] S1: Electrode slurry preparation: Mix silver-silicon-carbon nanotube-nano titanium dioxide composite hybrid electrode material (70%), carbon black (20%), polyvinylidene fluoride powder (8%) and polytetrafluoroethylene powder (2%), then mix with N-methylpyrrolidone solvent and magnetically stir for 3 hours to form a uniform thick slurry.

[0059] S2: Electrode plate pressing: The mixed slurry is coated onto the nickel foam and placed in a vacuum oven at 70°C for 24 hours to remove the N-methylpyrrolidone solvent. Then, the nickel foam is pressed at 15 MPa.

[0060] S3: Electrode plate electrical connection: Physically connect the electrode material to the amine liquid electroadsorption device.

[0061] 3. Process parameter control and results

[0062] The specific surface area of ​​the prepared composite electrode material is ~72 m². 2 ·g -1 The specific capacitance is ~104 F·g -1 A 0.7V voltage was applied to the electrode plates on both sides of the adsorption tank using a DC regulated power supply, and the adsorption tank contained an initial concentration of 270-290 mg·L⁻¹. - 1. A heat-stable salt MDEA solution is continuously circulated through a heat-stable salt removal electrode device (i.e. Figure 1 The device was used for 24 hours. By using a UV-VIS spectrophotometer to assess the concentration of the heat-stable salt in the MDEA solution, it was determined that the removal rate of the heat-stable salt by the electrode material could reach over 82%.

[0063] Example 2

[0064] 1. Preparation of composite electrode materials

[0065] (1) Acidification treatment of carbon nanotubes: Carbon nanotubes are immersed in an acidic solution composed of concentrated sulfuric acid (98% by mass) and nitric acid (68% by mass), with the ratio of concentrated sulfuric acid to nitric acid controlled at 3:1. The carbon nanotubes are heated and refluxed or sonicated at 100°C for 8 hours. Then the system is diluted with deionized water and allowed to stand for 12 hours. After standing and separating, the layers are washed by deionized water filtration. The product is dried in a vacuum drying oven at 70°C for 10 hours.

[0066] (2) Siloxane modification of acidified carbon nanotube surface: acidified carbon nanotube and KH550 organosiloxane were added to an ethanol aqueous solution, and the molar ratio of carbon nanotube and silane was controlled at 6:1. The reaction was carried out in a constant temperature water bath at 80℃ for 6h, cooled to room temperature, filtered and washed, and the product was dried in a vacuum drying oven at 80℃ for 8h to complete the siloxane modification.

[0067] (3) Preparation of carbon nanotube silica sol: The above siloxane-functionalized carbon nanotubes were mixed with toluene and treated with hydrolysis and condensation reaction at 80°C for 24 h to prepare sol solution.

[0068] (4) Introduction of silver active sites: Silver nitrate solution was added to the above carbon nanotube silica sol solution, and then chemically reduced by hydrazine hydrate to synthesize silver-silicon-carbon nanotube hybrid material. The hybrid material was thoroughly washed with deionized water to remove unreacted substances, and then dried in an oven at a controlled temperature of 120°C.

[0069] (5) Nano-titanium dioxide composite: Tetrabutyl titanate, glacial acetic acid, and anhydrous ethanol were mixed in a volume ratio of 1:1:2 and stirred mechanically or electromagnetically until homogeneous. Then, under rapid stirring, anhydrous ethanol and deionized water were mixed in a volume ratio of 1:1, and the pH was adjusted to 3 with nitric acid solution. The mixture was slowly added dropwise, and the temperature was controlled at 25°C. The mixture was stirred continuously for 3 hours and allowed to stand for 4 hours to complete the preparation of the titanium dioxide gel. The titanium dioxide gel was then mixed with the hybrid material in which silver active sites were successfully introduced in step (4), stirred until homogeneous, and then dried in an oven at 100°C for 3 hours. Finally, it was cooled to room temperature.

[0070] 2. Electrode preparation

[0071] S1: Electrode slurry preparation: Mix silver-silicon-carbon nanotube-nano titanium dioxide composite hybrid electrode material (80%), carbon black (10%), polyvinylidene fluoride powder (8%) and polytetrafluoroethylene powder (2%), then mix with N-methylpyrrolidone solvent, and stir mechanically or magnetically for 3 hours to form a uniform thick slurry.

[0072] S2: Electrode plate pressing: The mixed slurry is coated onto foamed nickel or foamed tin and placed in a vacuum oven at 80°C for 24 hours to remove N-methylpyrrolidone solvent. Then, the foamed nickel or foamed tin is pressed at 18MPa.

[0073] S3: Electrode plate electrical connection: Physically connect the electrode material to the amine liquid electroadsorption device.

[0074] 3. Process parameter control and results

[0075] The specific surface area of ​​the prepared composite electrode material is ~74 m². 2 ·g -1 The specific capacitance is ~108 F·g -1 A voltage of 0.8V was applied to the electrode plates on both sides of the adsorption tank using a DC regulated power supply, and the adsorption tank contained an initial concentration of 270-290 mg·L⁻¹. -1 The MDEA solution of the heat-stable salt is continuously circulated through the heat-stable salt removal electrode device (i.e. Figure 1 The device was used for 24 hours. By using a UV-VIS spectrophotometer to assess the concentration of the heat-stable salt in the MDEA solution, it was determined that the removal rate of the heat-stable salt by the electrode material could reach over 87%.

[0076] Example 3

[0077] 1. Preparation of composite electrode materials

[0078] (1) Acidification treatment of carbon nanotubes: Carbon nanotubes are immersed in an acidic solution composed of concentrated sulfuric acid (98% by mass) and nitric acid (68% by mass), with the ratio of concentrated sulfuric acid to nitric acid controlled at 2:1. The carbon nanotubes are heated and refluxed or sonicated at 120°C for 6 hours. Then the system is diluted with deionized water and allowed to stand for 12 hours. After standing and separating, the layers are washed by deionized water filtration. The product is dried in a vacuum drying oven at 70°C for 12 hours.

[0079] (2) Siloxane modification of acidified carbon nanotube surface: acidified carbon nanotube and KH560 organosiloxane were added to an ethanol aqueous solution, and the molar ratio of carbon nanotube and silane was controlled at 4:1. The reaction was carried out in a constant temperature water bath at 80℃ for 10h, cooled to room temperature, filtered and washed, and the product was dried in a vacuum drying oven at 80℃ for 12h to complete the siloxane modification.

[0080] (3) Preparation of carbon nanotube silica sol: The above siloxane-functionalized carbon nanotubes were mixed with toluene and treated with hydrolysis and condensation reaction at 80°C for 24 h to prepare sol solution.

[0081] (4) Introduction of silver active sites: Silver nitrate solution was added to the above carbon nanotube silica sol solution, and then chemically reduced by hydrazine hydrate to synthesize silver-silicon-carbon nanotube hybrid material. The hybrid material was thoroughly washed with deionized water to remove unreacted substances, and then dried in an oven at a controlled temperature of 120°C.

[0082] (5) Nano-titanium dioxide composite: Tetrabutyl titanate, glacial acetic acid, and anhydrous ethanol were mixed in a volume ratio of 1:1:2 and stirred mechanically or electromagnetically until homogeneous. Then, under rapid stirring, anhydrous ethanol and deionized water were mixed in a volume ratio of 1:1, and the pH was adjusted to 3 with nitric acid solution. The mixture was slowly added dropwise, and the temperature was controlled at 25°C. The mixture was stirred continuously for 3 hours and then allowed to stand for 3 hours to age, thus completing the preparation of the titanium dioxide gel. The titanium dioxide gel was then mixed with the hybrid material in which silver active sites were successfully introduced in step (4), stirred until homogeneous, and then dried in an oven at 120°C for 4 hours.

[0083] 2. Electrode preparation

[0084] S1: Electrode slurry preparation: Mix silver-silicon-carbon nanotube-nano titanium dioxide composite hybrid electrode material (80%), carbon black (10%), polyvinylidene fluoride powder (8%) and polytetrafluoroethylene powder (2%), then mix with N-methylpyrrolidone solvent, and stir mechanically or magnetically for 3 hours to form a uniform thick slurry.

[0085] S2: Electrode plate pressing: The mixed slurry is coated onto foamed nickel or foamed tin and placed in a vacuum oven at 90°C for 24 hours to remove N-methylpyrrolidone solvent. Then, the foamed nickel or foamed tin is pressed at 15MPa.

[0086] S3: Electrode plate electrical connection: Physically connect the electrode material to the amine liquid electroadsorption device.

[0087] 3. Process parameter control and results

[0088] The specific surface area of ​​the prepared composite electrode material is ~80m². 2 ·g -1 The specific capacitance is ~125 F·g -1 A 1.0V voltage was applied to the electrode plates on both sides of the adsorption tank using a DC regulated power supply, and the adsorption tank contained an initial concentration of 270-290 mg·L⁻¹. -1 The MDEA solution of the heat-stable salt is continuously circulated through the heat-stable salt removal electrode device (i.e. Figure 1 The device was used for 24 hours. By using a UV-VIS spectrophotometer to assess the concentration of the heat-stable salt in the MDEA solution, it was determined that the electrode material could remove more than 90% of the heat-stable salt.

[0089] Comparative Example 1

[0090] Keeping the other steps in Example 1 unchanged, only the nano-titanium dioxide composite step is removed, and a silver-silicon-carbon nanotube composite hybrid electrode material is finally formed. The removal rate of thermally stable salts by this electrode material decreases from 82% to 71%.

[0091] Comparative Example 2

[0092] Keeping the other steps in Example 2 unchanged, but changing the composition and ratio of the electrode slurry, the mass percentage of the silver-silicon-carbon nanotube-nano titanium dioxide composite hybrid electrode material was adjusted to 40%, carbon black to 50%, and polyvinylidene fluoride powder to 10%. After mixing, the removal rate of heat-stable salts by the electrode material decreased from 87% to 65%.

[0093] Comparative Example 3

[0094] Keeping the other steps in Example 3 unchanged, when the voltage applied to the electrode plates on both sides of the adsorption tank is adjusted to 0.3V, the removal rate of heat-stable salt by the electrode material decreases from 90% to 72%.

[0095] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing an electrode material, characterized in that: Includes the following steps: (1) Acidification treatment of carbon nanotubes: Immerse carbon nanotubes in an acidic solution, heat and reflux or sonicate the carbon nanotubes, dilute with water, let stand, filter and wash, and dry the product to obtain acidified carbon nanotubes. (2) Add acidified carbon nanotubes and organosiloxanes to an aqueous ethanol solution, react in a constant temperature water bath, cool to room temperature, filter and wash, and dry the product to obtain modified carbon nanotubes. (3) Preparation of carbon nanotube silica sol: Modified carbon nanotubes are mixed with toluene and then subjected to hydrolysis and condensation reaction to obtain carbon nanotube sol solution; (4) Introduction of silver active sites; Silver nitrate solution was added to carbon nanotube silica sol solution, and silver-silicon-carbon nanotube hybrid material was synthesized by chemical reduction with hydrazine hydrate. (5) Nano-titanium dioxide composite: Tetrabutyl titanate, glacial acetic acid and anhydrous ethanol are mixed in a volume ratio of 1:1:2 and stirred evenly. Anhydrous ethanol and water are mixed in a volume ratio of 1:1, pH value is controlled at 3, and slowly dripped in. The temperature is controlled at 25℃ and stirred continuously for 3 hours. After standing and aging for 3 hours, titanium dioxide gel is obtained. The titanium dioxide gel is mixed with the silver-silicon-carbon nanotube hybrid material in step (4), stirred evenly, dried, and dried at a temperature of 120℃ for 4 hours. After cooling, silver-silicon-carbon nanotube-nano-titanium dioxide composite hybrid electrode material is obtained.

2. The preparation method according to claim 1, characterized in that: The acidic solution mentioned in step (1) is concentrated sulfuric acid and nitric acid.

3. The preparation method according to claim 2, characterized in that: The volume ratio of concentrated sulfuric acid to nitric acid is 2:1 to 4:

1.

4. The preparation method according to claim 1, characterized in that: The temperature of the heating reflux in step (1) is 90-120℃; the heating reflux or ultrasonic treatment time is 3-8h; the standing time is 6-12h; the drying temperature is 60-80℃ and the time is 8-12h.

5. The preparation method according to claim 1, characterized in that: The organosiloxanes mentioned in step (2) include one or more of KH560, KH550, and KH690.

6. The preparation method according to claim 1, characterized in that: The molar ratio of carbon nanotubes and organosiloxanes in step (2) is 3:1-9:

1.

7. The preparation method according to claim 1, characterized in that: The hydrolysis and condensation reaction in step (3) is carried out at a temperature of 80-100℃ for 18-24 hours.

8. The electrode material prepared by the preparation method according to any one of claims 1-7.

9. A method for preparing an electrode, characterized in that: Includes the following steps: S1: Electrode slurry preparation: The electrode material described in claim 8, carbon black, polyvinylidene fluoride powder and polytetrafluoroethylene powder are mixed, and then mixed with N-methylpyrrolidone solvent and stirred to obtain a mixed slurry; S2: Electrode plate pressing: The mixed slurry is coated onto foamed nickel or foamed tin, placed under vacuum conditions, and pressed to obtain the final product.

10. The electrode prepared by the preparation method according to claim 9.

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