A preparation method of a sulfonated polythiophene modified nitrogen-doped honeycomb carbon and Co9S8 composite microsphere integrated flow electrode
By preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene, the problems of low specific capacitance of electrode materials and poor conductivity of ion exchange membranes in FCDI were solved, and the effect of efficient treatment of uranium-containing wastewater was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- EAST CHINA UNIV OF TECH
- Filing Date
- 2026-06-04
- Publication Date
- 2026-07-03
AI Technical Summary
In existing FCDI technology, the electrode materials have low specific capacitance and low adsorption capacity, and the ion exchange membranes have poor conductivity and ion permeability, resulting in low efficiency and high energy consumption in treating uranium-containing wastewater.
An integrated flow electrode using nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene was developed. The core-shell structure electrode material was formed by preparing chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres, combined with high-temperature carbonization and sulfonation treatment. The electrode surface was then coated with a sulfonated polythiophene film to improve the specific capacitance of the electrode material and the conductivity of the film.
It significantly improves the specific capacitance of electrode materials and the conductivity and permeability of ion exchange membranes, simplifies FCDI devices, reduces energy consumption, and improves the treatment efficiency and uranium removal rate of uranium-containing wastewater.
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Figure CN122324937A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical separation materials technology, and particularly relates to a method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene. Background Technology
[0002] The nuclear fuel cycle, including uranium mining and uranium separation and purification, generates large amounts of uranium-containing wastewater. This wastewater contains U(VI), which is highly soluble in water and highly mobile, at concentrations reaching mg / L. Untreated uranium-containing wastewater can easily cause long-term pollution of water sources and soil. U(VI) accumulates in plants and animals through the food chain, posing a serious threat to human health and ecological security. Therefore, developing economical and effective methods to separate uranium from uranium-containing wastewater is of great significance, as it allows for the recovery of uranium resources while reducing radioactive pollution.
[0003] Flow electrode deionization (FCDI) technology utilizes the synergistic effect of ion exchange membranes and electric fields to efficiently remove U(VI) ions from water, providing an economical and effective method for the resource-based treatment of uranium-containing wastewater. The basic principle of FCDI is that, under the influence of an electric field, target ions pass through an ion exchange membrane and are enriched in a flowing electrode slurry by means of double-layer capacitance or pseudocapacitance. Once the electrode is saturated, online regeneration can be achieved by shorting it or applying a reverse electric field. Compared to traditional capacitive deionization (CDI) using fixed electrodes, FCDI overcomes the bottleneck of limited adsorption capacity through continuous regeneration of the flowing electrode and can achieve long-term continuous operation. Furthermore, the system does not require high-pressure operation, resulting in relatively low equipment cost and maintenance difficulty. In summary, FCDI treatment of uranium-containing wastewater has the advantages of low energy consumption, low cost, and easy regeneration.
[0004] The key to treating uranium-containing wastewater using FCDI lies in designing high-performance electrode and membrane materials. However, conventional carbon electrode materials (such as activated carbon, graphene, and carbon nanotubes) are double-layer capacitor materials with low specific capacitance, resulting in low adsorption capacity. Furthermore, carbon materials are dominated by numerous irregular micropores, increasing ion diffusion resistance and hindering the rapid formation of the double layer, thus affecting ion enrichment efficiency. In addition, traditional FCDI units typically use ion exchange membranes separated from electrodes, and membrane performance directly determines ion migration efficiency. Currently available ion exchange membranes suffer from poor conductivity and ion permeability, which significantly increases system internal resistance and leads to increased energy consumption.
[0005] Therefore, how to effectively improve the specific capacitance of FCDI electrode materials, improve their pore structure, and enhance the conductivity and permeability of ion exchange membranes has become a key technical issue in the treatment of uranium-containing wastewater using FCDI. Summary of the Invention
[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene, thereby solving the problems of low specific capacitance, low adsorption capacity, and poor conductivity and ion permeability of electrode materials in existing FCDI technologies. In addition, the present invention also provides an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene and its application in flow electrode deionization technology.
[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene, comprising the following steps: Preparation of S10, chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres, including: S101. Dissolve chitosan in dilute acetic acid solution, add cobalt source and sulfur source to the solution, mix well, add crosslinking agent, and carry out crosslinking aging to obtain mixed viscous liquid; S102. The mixed viscous liquid is dripped into the oil phase, dispersed, heated to solidify, and separated to obtain spherical gel microspheres; S103. The spherical gel microspheres are subjected to solvent replacement and freeze-drying to prepare chitosan-based aerogel microsphere precursors. S104. Under the protection of an inert gas, the chitosan-based aerogel microsphere precursor is subjected to high-temperature carbonization treatment to form a nitrogen-doped carbon framework by carbonization of chitosan and in-situ generation of Co9S8 nanoparticles to obtain carbonization products. S105. Grind and sieve the carbonization product to obtain chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres. Preparation of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with S20 and sulfonated polythiophene, including: S201. The nitrogen-doped honeycomb carbon and Co9S8 composite microspheres prepared in S10 are ultrasonically dispersed in a mixed solution containing thiophene monomer and 3-sulfonated thiophene monomer. An oxidant is added to carry out a polymerization reaction, and sulfonated polythiophene is coated on the surface of the composite microspheres. After separation, washing and drying, the nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene are obtained.
[0008] Furthermore, in S101, the weight of chitosan is 1.0-2.0g; the volume of dilute acetic acid is 100 mL and the concentration is 2wt%; the cobalt source is cobalt nitrate hexahydrate, the sulfur source is thiourea; and the crosslinking agent is epichlorohydrin.
[0009] Furthermore, in S102, the oil phase is liquid paraffin; the heating and curing temperature is 70°C, and the time is 1 hour; the separation method is vacuum filtration.
[0010] Furthermore, in S103, solvent replacement is carried out using a 70 wt.% ethanol solution; the freeze-drying conditions are -60°C vacuum drying for 48 hours.
[0011] Furthermore, in S104, the inert gas is nitrogen; the high-temperature carbonization treatment specifically involves heating to 380°C at a rate of 4°C / min and holding for 1 hour, then heating to 800°C and holding for 1 hour.
[0012] Furthermore, in S20, the concentrations of thiophene monomer and 3-sulfonate thiophene monomer in the mixed solution are the same, both being 0.1-0.3 mol / L; the oxidant is ferric chloride / acetonitrile solution; the polymerization reaction is carried out under ice bath conditions for 1 hour; the separation method is vacuum filtration; washing is performed using deionized water and methanol; and the drying conditions are vacuum drying at 60°C for 24 hours.
[0013] Furthermore, in S101, the mass of chitosan is 1.5g.
[0014] Furthermore, in S201, the concentrations of both the thiophene monomer and the 3-sulfothiophene monomer are 0.2 mol / L.
[0015] Secondly, the present invention also provides an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene. The electrode has a core-shell structure, wherein the core is a chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microsphere, the shell is a sulfonated polythiophene film, and Co9S8 nanoparticles are uniformly embedded on the nitrogen-doped honeycomb frame.
[0016] Thirdly, the present invention also provides an application of an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene in flow electrode deionization technology for the treatment of uranium-containing wastewater.
[0017] The method for preparing the integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene provided by the present invention has at least the following advantages compared with the prior art: (1) When chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres are synthesized in this invention, chitosan can be used as both a carbon source and a nitrogen dopant (chitosan itself contains nitrogen); at the same time, through high-temperature carbonization, Co9S8 nanoparticles are uniformly embedded in the carbon skeleton, which is beneficial to fully expose sulfur active sites and selectively bind U(VI) through S. In addition, using chitosan-based composite aerogel with well-developed honeycomb pore structure as a precursor, its honeycomb pore structure can still be retained after high-temperature carbonization to obtain chitosan-derived honeycomb carbon, which is beneficial to the rapid embedding of U(VI) during electroadsorption.
[0018] (2) This invention utilizes chitosan-derived nitrogen-doped honeycomb carbon to in-situ load transition metal sulfides (Co9S8), and utilizes the double-layer capacitance provided by carbon materials to hybridize with the pseudocapacitance provided by Co9S8, which can significantly improve the specific capacitance of the electrode material. This invention utilizes sulfonated polythiophene as an ion-exchange conductive polymer to modify the surface of the electrode material into a thin film, which can reduce the thickness of the ion-exchange membrane, increase the membrane conductivity and ion selective permeability, and thus improve the uranium separation performance of FCDI.
[0019] (3) This invention combines the traditional FCDI electrode material and the ion exchange membrane into one by constructing an integrated flow electrode material coupled with a high specific capacitance hybrid electrode material and a conductive ion exchange membrane (sulfonated polythiophene membrane), which simplifies the FCDI device; after modification with sulfonated polythiophene, an effective conductive channel can be formed between nitrogen-doped honeycomb carbon and Co9S8 particles, which improves the overall conductivity of the electrode material and the actual effect of FCDI in treating uranium-containing wastewater. Attached Figure Description
[0020] To more clearly illustrate the solution of the present invention, a brief introduction will be given to the drawings used in the description of the embodiments below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0021] Figure 1 A flowchart illustrating the preparation method of the integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene provided in this embodiment of the invention; Figure 2 Scanning electron microscope image of an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene provided in this embodiment of the invention before uranium separation by FCDI; Figure 3 Scanning electron microscope (SEM) image of an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene, provided in an embodiment of the present invention, after uranium separation by FCDI. Detailed Implementation
[0022] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.
[0023] 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. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
[0024] Example 1
[0025] Preparation of S10, chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres, including: S101, Crosslinking and Aging: Dissolve 1.5 g of chitosan completely in 100 mL of dilute acetic acid (2 wt%) solution to prepare a homogeneous solution. Add 1.62 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 0.42 g of thiourea (CH4N2S) (molar ratio approximately 9:8, with a slight excess of thiourea) to the above solution, and stir thoroughly to form a homogeneous mixture. Slowly add 2 mL of epichlorohydrin crosslinking agent to the above sol. Stir the mixture at 60°C for 30 min for pre-crosslinking. The crosslinking agent promotes the formation of a three-dimensional network structure of the polymer chains, thus reducing the carbon content of the chitosan. 2+ The sulfur source is in situ complexed or captured in the network. The mixture is then aged at 50°C for 30 minutes to form a homogeneous, viscous liquid.
[0026] S102. Shaping and Curing: The above hydrogel is dropped into 100 mL of liquid paraffin oil phase under high-speed stirring. Under the action of stirring shear force, it is fully dispersed to form spherical gel particles, and further cross-linked and cured by heating at 70°C for 1 h. Then stirring is stopped, and after demulsification, the spherical gel microspheres are collected by vacuum filtration.
[0027] S103, Freeze-drying: The above-mentioned spherical aerogel microspheres were immersed in 50 mL of 70 wt.% ethanol solution to gradually displace the internal water. Then, the microspheres were pre-frozen at -20°C for 2 hours to "freeze" their internal structure. They were then placed in a freeze dryer and dried under vacuum at -60°C for 48 hours to prepare the chitosan-based aerogel microsphere precursor.
[0028] S104. High-Temperature Carbonization: The chitosan-based aerogel microsphere precursor prepared above was placed in a tube furnace and heat-treated under nitrogen protection. The temperature was increased to 380°C at a rate of 4°C / min and held for 1 hour. During this stage, the polymer decomposed and cross-linked, and thiourea decomposed to produce sulfur-containing gas, which began to react with cobalt ions. The temperature was further increased to 800°C and held for 1 hour. At this temperature, the polymer carbonized to form a nitrogen-doped conductive carbon framework; simultaneously, cobalt ions reacted with the sulfur source to generate Co9S8 nanoparticles in situ, which were uniformly embedded on the carbon framework.
[0029] S105. Grinding and sieving: After the above carbonization and sulfidation processes are completed, the mixture is naturally cooled to room temperature and then ground and sieved to obtain chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres with a particle size of <200μm.
[0030] Preparation of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with S20 and sulfonated polythiophene, including: 1.0 g of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres were ultrasonically dispersed in 20 mL of a mixed solution containing equal amounts of thiophene monomer and 3-sulfonated thiophene monomer (both monomers were at the same concentration, dissolved in acetonitrile, each at 0.1 mol / L). 2.5 mL of a 1 mol / L ferric chloride / acetonitrile solution was slowly added dropwise to the dispersion system, and polymerization was carried out in an ice bath to coat the carbon microspheres with sulfonated polythiophene. After 1 h of reaction, the solid product was separated by vacuum filtration, repeatedly washed with deionized water and methanol to remove unreacted residues, and then vacuum dried at 60°C for 24 h to obtain nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene.
[0031] Results: The electrochemical performance and hydrophilicity of the integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene showed that its specific capacitance was 286.4 F / g and the contact angle of the aqueous solution was 58.7° after 1 s of contact.
[0032] Using the aforementioned integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene as the working parallel electrode (each flow electrode mass 25 mg, flow electrode slurry solid-liquid ratio 0.20 g / L), it was used to treat 1 L of uranium-containing wastewater with a concentration of 25 mg / L via FCDI. The results showed a uranium removal rate of 72%, an electroadsorption uranium capacity of 360 mg / g, an electroadsorption equilibrium time of 85 min, and a membrane permeation flux of 0.056 m³ / g. 3 / (m 2 . h).
[0033] Example 2
[0034] Preparation of S10, chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres, including: S101, Crosslinking and Aging: Dissolve 1.5 g of chitosan completely in 100 mL of dilute acetic acid (2 wt%) solution to prepare a homogeneous solution. Add 1.62 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 0.42 g of thiourea (CH4N2S) (molar ratio approximately 9:8, with a slight excess of thiourea) to the above solution, and stir thoroughly to form a homogeneous mixture. Slowly add 2 mL of epichlorohydrin crosslinking agent to the above sol. Stir the mixture at 60°C for 30 min for pre-crosslinking. The crosslinking agent promotes the formation of a three-dimensional network structure of the polymer chains, thus reducing the carbon content of the chitosan. 2+ The sulfur source is in situ complexed or captured in the network. The mixture is then aged at 50°C for 30 minutes to form a homogeneous, viscous liquid.
[0035] S102. Shaping and Curing: The above hydrogel is dropped into 100 mL of liquid paraffin oil phase under high-speed stirring. Under the action of stirring shear force, it is fully dispersed to form spherical gel particles, and further cross-linked and cured by heating at 70°C for 1 h. Then stirring is stopped, and after demulsification, the spherical gel microspheres are collected by vacuum filtration.
[0036] S103, Freeze-drying: The above-mentioned spherical aerogel microspheres were immersed in 50 mL of 70 wt.% ethanol solution to gradually displace the internal water. Then, the microspheres were pre-frozen at -20°C for 2 hours to "freeze" their internal structure. They were then placed in a freeze dryer and dried under vacuum at -60°C for 48 hours to prepare the chitosan-based aerogel microsphere precursor.
[0037] S104. High-Temperature Carbonization: The chitosan-based aerogel microsphere precursor prepared above was placed in a tube furnace and heat-treated under nitrogen protection. The temperature was increased to 380°C at a rate of 4°C / min and held for 1 hour. During this stage, the polymer decomposed and cross-linked, and thiourea decomposed to produce sulfur-containing gas, which began to react with cobalt ions. The temperature was further increased to 800°C and held for 1 hour. At this temperature, the polymer carbonized to form a nitrogen-doped conductive carbon framework; simultaneously, cobalt ions reacted with the sulfur source to generate Co9S8 nanoparticles in situ, which were uniformly embedded on the carbon framework.
[0038] S105. Grinding and sieving: After the above carbonization and sulfidation processes are completed, the mixture is naturally cooled to room temperature and then ground and sieved to obtain chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres with a particle size of <200μm.
[0039] Preparation of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with S20 and sulfonated polythiophene, including: 1.0 g of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres were ultrasonically dispersed in 20 mL of a mixed solution containing equal amounts of thiophene monomer and 3-sulfonated thiophene monomer (both monomers were at the same concentration, dissolved in acetonitrile to prepare a solution of 0.2 mol / L). 2.5 mL of a 1 mol / L ferric chloride / acetonitrile solution was slowly added dropwise to the dispersion system, and polymerization was carried out in an ice bath to coat the carbon microspheres with sulfonated polythiophene. After 1 h of reaction, the solid product was separated by vacuum filtration, repeatedly washed with deionized water and methanol to remove unreacted residues, and then vacuum dried at 60°C for 24 h to obtain nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene.
[0040] Results: The electrochemical performance and hydrophilicity of the integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene showed that its specific capacitance was 358.2 F / g and the contact angle of the aqueous solution was 53.2° after 1 s of contact.
[0041] Using the aforementioned integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene as the working parallel electrode (each flow electrode mass 25 mg, flow electrode slurry solid-liquid ratio 0.20 g / L), it was used to treat 1 L of uranium-containing wastewater with a concentration of 25 mg / L via FCDI. The results showed a uranium removal rate of 93%, an electroadsorption uranium capacity of 465 mg / g, an electroadsorption equilibrium time of 85 min, and a membrane permeation flux of 0.052 m³ / g. 3 / (m 2 . h).
[0042] Example 3
[0043] Preparation of S10, chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres, including: S101, Crosslinking and Aging: Dissolve 1.5 g of chitosan completely in 100 mL of dilute acetic acid (2 wt%) solution to prepare a homogeneous solution. Add 1.62 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 0.42 g of thiourea (CH4N2S) (molar ratio approximately 9:8, with a slight excess of thiourea) to the above solution, and stir thoroughly to form a homogeneous mixture. Slowly add 2 mL of epichlorohydrin crosslinking agent to the above sol. Stir the mixture at 60°C for 30 min for pre-crosslinking. The crosslinking agent promotes the formation of a three-dimensional network structure of the polymer chains, thus reducing the carbon content of the chitosan. 2+ The sulfur source is in situ complexed or captured in the network. The mixture is then aged at 50°C for 30 minutes to form a homogeneous, viscous liquid.
[0044] S102. Shaping and Curing: The above hydrogel is dropped into 100 mL of liquid paraffin oil phase under high-speed stirring. Under the action of stirring shear force, it is fully dispersed to form spherical gel particles, and further cross-linked and cured by heating at 70°C for 1 h. Then stirring is stopped, and after demulsification, the spherical gel microspheres are collected by vacuum filtration.
[0045] S103, Freeze-drying: The above-mentioned spherical aerogel microspheres were immersed in 50 mL of 70 wt.% ethanol solution to gradually displace the internal water. Then, the microspheres were pre-frozen at -20°C for 2 hours to "freeze" their internal structure. They were then placed in a freeze dryer and dried under vacuum at -60°C for 48 hours to prepare the chitosan-based aerogel microsphere precursor.
[0046] S104. High-Temperature Carbonization: The chitosan-based aerogel microsphere precursor prepared above was placed in a tube furnace and heat-treated under nitrogen protection. The temperature was increased to 380°C at a rate of 4°C / min and held for 1 hour. During this stage, the polymer decomposed and cross-linked, and thiourea decomposed to produce sulfur-containing gas, which began to react with cobalt ions. The temperature was further increased to 800°C and held for 1 hour. At this temperature, the polymer carbonized to form a nitrogen-doped conductive carbon framework; simultaneously, cobalt ions reacted with the sulfur source to generate Co9S8 nanoparticles in situ, which were uniformly embedded on the carbon framework.
[0047] S105. Grinding and sieving: After the above carbonization and sulfidation processes are completed, the mixture is naturally cooled to room temperature and then ground and sieved to obtain chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres with a particle size of <200μm.
[0048] Preparation of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with S20 and sulfonated polythiophene, including: 1.0 g of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres were ultrasonically dispersed in 20 mL of a mixed solution containing equal amounts of thiophene monomer and 3-sulfonated thiophene monomer (both monomers were at the same concentration, dissolved in acetonitrile, each at 0.3 mol / L). 2.5 mL of a 1 mol / L ferric chloride / acetonitrile solution was slowly added dropwise to the dispersion system, and polymerization was carried out in an ice bath to coat the carbon microspheres with sulfonated polythiophene. After 1 h of reaction, the solid product was separated by vacuum filtration, repeatedly washed with deionized water and methanol to remove unreacted residues, and then vacuum dried at 60°C for 24 h to obtain nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene.
[0049] Results: The electrochemical performance and hydrophilicity of the integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene showed that its specific capacitance was 325.2 F / g and the contact angle of the aqueous solution was 52° after 1 s contact.
[0050] Using the aforementioned integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene as the working parallel electrode (each flow electrode mass 25 mg, flow electrode slurry solid-liquid ratio 0.20 g / L), it was used to treat 1 L of uranium-containing wastewater with a concentration of 25 mg / L using FCDI. The results showed a uranium removal rate of 83%, an electroadsorption uranium capacity of 415 mg / g, an electroadsorption equilibrium time of 120 min, and a membrane permeation flux of 0.037 m³ / g. 3 / (m 2 . h).
[0051] Example 4
[0052] Preparation of S10, chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres, including: S101, Crosslinking and Aging: Dissolve 1.0 g of chitosan completely in 100 mL of dilute acetic acid (2 wt%) solution to prepare a homogeneous solution. Add 1.62 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 0.42 g of thiourea (CH4N2S) (molar ratio approximately 9:8, with a slight excess of thiourea) to the above solution, and stir thoroughly to form a homogeneous mixture. Slowly add 2 mL of epichlorohydrin crosslinking agent to the above sol. Stir the mixture at 60°C for 30 min for pre-crosslinking. The crosslinking agent promotes the formation of a three-dimensional network structure of the polymer chains, thus reducing the carbon dioxide content of the chitosan. 2+ The sulfur source is in situ complexed or captured in the network. The mixture is then aged at 50°C for 30 minutes to form a homogeneous, viscous liquid.
[0053] S102. Shaping and Curing: The above hydrogel is dropped into 100 mL of liquid paraffin oil phase under high-speed stirring. Under the action of stirring shear force, it is fully dispersed to form spherical gel particles, and further cross-linked and cured by heating at 70°C for 1 h. Then stirring is stopped, and after demulsification, the spherical gel microspheres are collected by vacuum filtration.
[0054] S103, Freeze-drying: The above-mentioned spherical aerogel microspheres were immersed in 50 mL of 70 wt.% ethanol solution to gradually displace the internal water. Then, the microspheres were pre-frozen at -20°C for 2 hours to "freeze" their internal structure. They were then placed in a freeze dryer and dried under vacuum at -60°C for 48 hours to prepare the chitosan-based aerogel microsphere precursor.
[0055] S104. High-Temperature Carbonization: The chitosan-based aerogel microsphere precursor prepared above was placed in a tube furnace and heat-treated under nitrogen protection. The temperature was increased to 380°C at a rate of 4°C / min and held for 1 hour. During this stage, the polymer decomposed and cross-linked, and thiourea decomposed to produce sulfur-containing gas, which began to react with cobalt ions. The temperature was further increased to 800°C and held for 1 hour. At this temperature, the polymer carbonized to form a nitrogen-doped conductive carbon framework; simultaneously, cobalt ions reacted with the sulfur source to generate Co9S8 nanoparticles in situ, which were uniformly embedded on the carbon framework.
[0056] S105. Grinding and sieving: After the above carbonization and sulfidation processes are completed, the mixture is naturally cooled to room temperature and then ground and sieved to obtain chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres with a particle size of <200μm.
[0057] Preparation of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with S20 and sulfonated polythiophene, including: 1.0 g of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres were ultrasonically dispersed in 20 mL of a mixed solution containing equal amounts of thiophene monomer and 3-sulfonated thiophene monomer (both monomers were at the same concentration, dissolved in acetonitrile to prepare a solution of 0.2 mol / L). 2.5 mL of a 1 mol / L ferric chloride / acetonitrile solution was slowly added dropwise to the dispersion system, and polymerization was carried out in an ice bath to coat the carbon microspheres with sulfonated polythiophene. After 1 h of reaction, the solid product was separated by vacuum filtration, repeatedly washed with deionized water and methanol to remove unreacted residues, and then vacuum dried at 60°C for 24 h to obtain nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene.
[0058] Results: The electrochemical performance and hydrophilicity of the integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene showed that its specific capacitance was 316.5 F / g and the contact angle of aqueous solution was 48.4° after 1 s contact.
[0059] Using the aforementioned integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene as the working parallel electrode (each flow electrode mass 25 mg, flow electrode slurry solid-liquid ratio 0.20 g / L), it was used to treat 1 L of uranium-containing wastewater with a concentration of 25 mg / L via FCDI. The results showed a uranium removal rate of 79%, an electroadsorption uranium capacity of 395 mg / g, an electroadsorption equilibrium time of 120 min, and a membrane permeation flux of 0.045 m³ / g. 3 / (m 2 . h).
[0060] Example 5
[0061] Preparation of S10, chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres, including: S101, Crosslinking and Aging: Dissolve 2.0 g of chitosan completely in 100 mL of dilute acetic acid (2 wt%) solution to prepare a homogeneous solution. Add 1.62 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 0.42 g of thiourea (CH4N2S) (molar ratio approximately 9:8, with a slight excess of thiourea) to the above solution, and stir thoroughly to form a homogeneous mixture. Slowly add 2 mL of epichlorohydrin crosslinking agent to the above sol. Stir the mixture at 60°C for 30 min for pre-crosslinking. The crosslinking agent promotes the formation of a three-dimensional network structure of the polymer chains, thus reducing the carbon dioxide content of the chitosan. 2+ The sulfur source is in situ complexed or captured in the network. The mixture is then aged at 50°C for 30 minutes to form a homogeneous, viscous liquid.
[0062] S102. Shaping and Curing: The above hydrogel is dropped into 100 mL of liquid paraffin oil phase under high-speed stirring. Under the action of stirring shear force, it is fully dispersed to form spherical gel particles, and further cross-linked and cured by heating at 70°C for 1 h. Then stirring is stopped, and after demulsification, the spherical gel microspheres are collected by vacuum filtration.
[0063] S103, Freeze-drying: The above-mentioned spherical aerogel microspheres were immersed in 50 mL of 70 wt.% ethanol solution to gradually displace the internal water. Then, the microspheres were pre-frozen at -20°C for 2 hours to "freeze" their internal structure. They were then placed in a freeze dryer and dried under vacuum at -60°C for 48 hours to prepare the chitosan-based aerogel microsphere precursor.
[0064] S104. High-Temperature Carbonization: The chitosan-based aerogel microsphere precursor prepared above was placed in a tube furnace and heat-treated under nitrogen protection. The temperature was increased to 380°C at a rate of 4°C / min and held for 1 hour. During this stage, the polymer decomposed and cross-linked, and thiourea decomposed to produce sulfur-containing gas, which began to react with cobalt ions. The temperature was further increased to 800°C and held for 1 hour. At this temperature, the polymer carbonized to form a nitrogen-doped conductive carbon framework; simultaneously, cobalt ions reacted with the sulfur source to generate Co9S8 nanoparticles in situ, which were uniformly embedded on the carbon framework.
[0065] S105. Grinding and sieving: After the above carbonization and sulfidation processes are completed, the mixture is naturally cooled to room temperature and then ground and sieved to obtain chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres with a particle size of <200μm.
[0066] Preparation of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with S20 and sulfonated polythiophene, including: 1.0 g of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres were ultrasonically dispersed in 20 mL of a mixed solution containing equal amounts of thiophene monomer and 3-sulfonated thiophene monomer (both monomers were at the same concentration, dissolved in acetonitrile, each at 0.1-0.3 mol / L). 2.5 mL of a 1 mol / L ferric chloride / acetonitrile solution was slowly added dropwise to the dispersion system, and polymerization was carried out in an ice bath to coat the carbon microspheres with sulfonated polythiophene. After 1 h of reaction, the solid product was separated by vacuum filtration, repeatedly washed with deionized water and methanol to remove unreacted residues, and then vacuum dried at 60°C for 24 h to obtain nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene.
[0067] Results: The electrochemical performance and hydrophilicity of the integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene showed that its specific capacitance was 297.2 F / g and the contact angle of the aqueous solution was 56.3° after 1 s of contact.
[0068] Using the aforementioned integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene as the working parallel electrode (each flow electrode mass 25 mg, flow electrode slurry solid-liquid ratio 0.20 g / L), it was used to treat 1 L of uranium-containing wastewater with a concentration of 25 mg / L via FCDI. The results showed a uranium removal rate of 76%, an electroadsorption uranium capacity of 380 mg / g, an electroadsorption equilibrium time of 90 min, and a membrane permeation flux of 0.050 m³ / g. 3 / (m 2 . h).
[0069] In summary, combining Figure 1 and Figure 3 The experimental results of treating 1L of uranium-containing wastewater with a concentration of 25 mg / L using FCDI in Examples 1 to 5 show that Example 2 (implemented according to the method of adding 1.5 g of chitosan in step S10 and 0.2 mol / L of both thiophene monomer and 3-sulfothiophene monomer in step S20) has the best effect on treating uranium-containing wastewater. At this time, the uranium removal rate reached 93%, the electroadsorption uranium capacity was 465 mg / g, the electroadsorption equilibrium time was 85 min, and the membrane permeation flux was 0.052 m. 3 / (m 2 . h).
[0070] As the concentrations of thiophene monomer and 3-sulfonated thiophene monomer increase (from 0.1 mol / L to 0.2 mol / L), the loading of sulfonated polythiophene increases, thereby improving the electrode specific capacitance and hydrophilicity. However, when the monomer concentration is too high (e.g., reaching 0.3 mol / L), the excessive loading of sulfonated polythiophene can clog the electrode pore structure, resulting in poor FCDI uranium separation performance. Furthermore, the optimal addition amount of chitosan is 1.5 g. Too low an addition amount leads to a low proportion of chitosan-derived carbon, making it difficult to provide a well-developed pore structure; while too high an addition amount results in an excessive proportion of chitosan-derived carbon, leading to a lower specific capacitance and reduced electroadsorption capacity. In summary, by adjusting the amount of chitosan added and the concentrations of the polymeric monomers (thiophene and 3-sulfonated thiophene), the performance of the electrode material can be optimized, giving it both a well-developed pore structure and the high pseudocapacitance provided by Co9S8 and the good ion exchange performance of sulfonated polythiophene, thus leveraging the synergistic effect of different components to achieve the best FCDI uranium separation performance.
[0071] Comparative Example 1 Commercially available high specific surface area activated carbon powder (YP-50F, specific surface area approximately 1800 m²) was selected. 2 The electrode material ( / g) was used for FCDI without any surface modification, without Co9S8 composite, and without sulfonated polythiophene coating. The electrode composition consisted of activated carbon powder, conductive carbon black, and PVDF binder (mass ratio 8:1:1).
[0072] The FCDI conditions were the same as in Examples 1 to 5, using a pair of parallel electrodes (each with a flow electrode mass of 25 mg and a flow electrode slurry solid-liquid ratio of 0.20 g / L) to treat 1 L of uranium-containing wastewater with a concentration of 25 mg / L.
[0073] The test results were as follows: specific capacitance 85.3 F / g, contact angle (1s) 112.5°, uranium removal rate 31%, electroadsorption uranium capacity 78 mg / g, electroadsorption equilibrium time 210 min, and membrane permeation flux 0.018 m. 3 / (m 2 . h).
[0074] In Comparative Example 1, activated carbon only provides double-layer capacitance, which has low specific capacitance and poor hydrophilicity. It has a small adsorption capacity for U(VI) and a slow adsorption rate. It does not integrate ion exchange membrane function, resulting in high internal resistance of the system.
[0075] Comparative Example 2 According to step S10 of Example 2 of the present invention, chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres are prepared, but the sulfonated polythiophene modification in step S20 is not performed. The nitrogen-doped honeycomb carbon and Co9S8 composite microspheres (without sulfonated polythiophene modification) electrode is directly used as the FCDI electrode material.
[0076] The FCDI conditions were the same as in the example, with a pair of parallel electrodes (each with a flow electrode mass of 25 mg and a flow electrode slurry solid-liquid ratio of 0.20 g / L) to treat 1 L of uranium-containing wastewater with a concentration of 25 mg / L.
[0077] The test results were as follows: specific capacitance was 203.6 F / g; contact angle (1 s) was 78.4°; uranium removal rate was 54%; electroadsorption uranium capacity was 135 mg / g; electroadsorption equilibrium time was 150 min; and membrane permeation flux was 0.025 m³ / g. 3 / (m 2 . h).
[0078] In Comparative Example 2, although Co9S8 provides pseudocapacitance, and its specific capacitance and wettability are superior to pure activated carbon, the electrode / solution interface has poor ion selectivity due to the lack of an ion-exchange conductive film layer of sulfonated polythiophene, resulting in lower uranium removal rate and adsorption capacity than in Examples 1 to 5 of the present invention.
[0079] In summary, compared with Comparative Example 1 (conventional activated carbon electrode), Example 2 of the present invention shows an approximately 200% increase in uranium removal rate (31% → 93%), an approximately 496% increase in electroadsorption capacity (78 mg / g → 465 mg / g), a approximately 60% reduction in equilibration time (210 min → 85 min), and an approximately 189% increase in membrane permeation flux (0.018 → 0.052 m). 3 / (m 2 Compared with Comparative Example 2 (composite microspheres without sulfonated polythiophene modification), Example 2 of the present invention showed a 72% increase in uranium removal rate (54%→93%), a 244% increase in electroadsorption capacity (135 mg / g→465 mg / g), and a 108% increase in membrane permeation flux (0.025→0.052 m). 3 / (m 2 The results (h) fully demonstrate the synergistic effect of nitrogen-doped honeycomb carbon modified with sulfonated polythiophene and Co9S8 composite microspheres, as well as the significant advantages of the integrated flow electrode design.
[0080] Compared with the prior art, the preparation method of the integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene described in the above embodiments allows chitosan to be used as both a carbon source and a nitrogen dopant (chitosan itself contains nitrogen) during the synthesis of chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres. At the same time, the high-temperature carbonization process allows the in-situ generated Co9S8 nanoparticles to be uniformly embedded in the carbon framework, which is beneficial for fully exposing sulfur active sites and selectively binding U(VI) through S. In addition, using chitosan-based composite aerogel with a well-developed honeycomb structure as a precursor, the honeycomb structure can still be retained after high-temperature carbonization to obtain chitosan-derived honeycomb carbon, which is beneficial for the rapid embedding of U(VI) during electroadsorption. This invention utilizes chitosan-derived nitrogen-doped honeycomb carbon to in-situ load transition metal sulfides (Co9S8). By hybridizing the double-layer capacitance provided by the carbon material with the pseudocapacitance provided by Co9S8, the specific capacitance of the electrode material can be significantly improved. Furthermore, this invention uses sulfonated polythiophene as an ion-exchange conductive polymer to modify the electrode material surface into a thin film, reducing the ion-exchange membrane thickness and increasing membrane conductivity and ion-selective permeability, thereby enhancing the uranium separation performance of FCDI. This invention integrates the traditional FCDI electrode material and ion-exchange membrane into a single, integrated flow electrode material by constructing a high-specific-capacitance hybrid electrode material coupled with a conductive ion-exchange membrane (sulfonated polythiophene membrane), simplifying the FCDI device. After modification with sulfonated polythiophene, an effective conductive channel is formed between the nitrogen-doped honeycomb carbon and Co9S8 particles, improving the overall conductivity of the electrode material and the actual effect of FCDI in treating uranium-containing wastewater.
[0081] Obviously, the embodiments described above are merely preferred embodiments of the present invention, and not all embodiments. The accompanying drawings illustrate preferred embodiments of the present invention, but do not limit the scope of the patent. The present invention can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this invention.
Claims
1. A method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene, characterized in that, Includes the following steps: Preparation of S10, chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres, including: S101. Dissolve chitosan in dilute acetic acid solution, add cobalt source and sulfur source to the solution, mix well, add crosslinking agent, and carry out crosslinking aging to obtain mixed viscous liquid; S102. The mixed viscous liquid is dripped into the oil phase, dispersed, heated to solidify, and separated to obtain spherical gel microspheres; S103. The spherical gel microspheres are subjected to solvent replacement and freeze-drying to prepare chitosan-based aerogel microsphere precursors. S104. Under the protection of an inert gas, the chitosan-based aerogel microsphere precursor is subjected to high-temperature carbonization treatment to form a nitrogen-doped carbon framework by carbonization of chitosan and in-situ generation of Co9S8 nanoparticles to obtain carbonization products. S105. Grind and sieve the carbonization product to obtain chitosan-derived nitrogen-doped honeycomb carbon and Co9S8 composite microspheres. Preparation of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with S20 and sulfonated polythiophene, including: S201. The nitrogen-doped honeycomb carbon and Co9S8 composite microspheres prepared in S10 are ultrasonically dispersed in a mixed solution containing thiophene monomer and 3-sulfonated thiophene monomer. An oxidant is added to carry out a polymerization reaction, and sulfonated polythiophene is coated on the surface of the composite microspheres. After separation, washing and drying, the nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene are obtained.
2. The method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene according to claim 1, characterized in that, In S101, the weight of chitosan is 1.0-2.0g; the volume of dilute acetic acid is 100 mL and the concentration is 2 wt%; the cobalt source is cobalt nitrate hexahydrate, the sulfur source is thiourea, and the crosslinking agent is epichlorohydrin.
3. The method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene according to claim 1, characterized in that, In S102, the oil phase is liquid paraffin; the heating and curing temperature is 70°C and the time is 1 hour; the separation method is vacuum filtration.
4. The method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene according to claim 1, characterized in that, In S103, solvent replacement is carried out using a 70 wt.% ethanol solution; the freeze-drying conditions are -60°C vacuum drying for 48 hours.
5. The method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene according to claim 1, characterized in that, In S104, the inert gas is nitrogen; the high-temperature carbonization treatment specifically involves heating to 380°C at a rate of 4°C / min and holding for 1 hour, then heating to 800°C and holding for 1 hour.
6. The method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene according to claim 1, characterized in that, In S20, the concentrations of thiophene monomer and 3-sulfothiophene monomer in the mixed solution are the same, both being 0.1-0.3 mol / L; the oxidant is ferric chloride / acetonitrile solution; the polymerization reaction is carried out under ice bath conditions for 1 hour; the separation method is vacuum filtration; washing is performed using deionized water and methanol; and the drying conditions are vacuum drying at 60°C for 24 hours.
7. The method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene according to claim 1, characterized in that, In S101, the mass of chitosan is 1.5g.
8. The method for preparing an integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene according to claim 1, characterized in that, In S201, the concentrations of both thiophene monomer and 3-sulfothiophene monomer are 0.2 mol / L.
9. A flow electrode made of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene, prepared by the method according to any one of claims 1 to 8, characterized in that, The electrode has a core-shell structure, wherein the core is a composite microsphere of chitosan-derived nitrogen-doped honeycomb carbon and Co9S8, the shell is a sulfonated polythiophene film, and Co9S8 nanoparticles are uniformly embedded in the nitrogen-doped honeycomb frame.
10. The application of the integrated flow electrode of nitrogen-doped honeycomb carbon and Co9S8 composite microspheres modified with sulfonated polythiophene as described in claim 9 in flow electrode deionization technology, characterized in that, Used for treating uranium-containing wastewater.