Porous material for electrochemical separation and extraction of bromine as well as preparation method and application of porous material

Abstract

The invention provides a porous material for electrochemically separating and extracting bromine as well as a preparation method and application of the porous material. The calcination temperature of the ZIF-8 precursor is 500 to 1200 DEG C, and the final selected temperature is 800 DEG C. The electro-adsorption material is a membrane electrode prepared from a ZIF-8 derivative nano carbon material (hereinafter referred to as NC-800) at 800 DEG C in a nitrogen atmosphere and PVDF. The mass ratio of the electroactive material NC-800 to the PVDF is (1-50): (0.1-5). The electro-adsorption material provided by the invention has relatively large adsorption capacity, good cycle stability and excellent selective adsorbability, still has relatively good adsorption capacity for a solution with the bromine ion content of 100 mg / L, and is suitable for being applied to extraction of bromine from brine.

Description

Technical Field

[0001] This invention belongs to the field of bromine extraction technology, specifically relating to an electroadsorption material for electrochemical extraction of bromine, its preparation method, and its application. Background Technology

[0002] Bromine is a non-renewable resource with limited reserves. Its distribution varies significantly across different water bodies, with underground bromine from oil and gas fields and salt lake bromine considered the most promising bromine sources due to their high bromine content. As a crucial basic chemical raw material, bromine plays an irreplaceable role in pharmaceutical synthesis and other fields. With the continued growth of the global economy, market demand for bromine is surging due to its non-renewable nature and uneven distribution. The bromine content in brines can generally reach 250 mg·L⁻¹, a concentration that meets the economic threshold for industrial-scale comprehensive utilization and individual extraction, providing a feasible basis for the large-scale development of brine resources and the efficient extraction of bromine.

[0003] The efficient and selective separation of ions from complex aqueous solutions is of great significance for resource recovery, energy storage, and environmental protection. While numerous ion separation technologies have been reported and industrialized, they generally suffer from environmental pollution, low extraction efficiency, and high costs, limiting their large-scale application in real-world scenarios. Electro-controlled ion exchange technology, with its significant advantages such as environmental friendliness, the ability to achieve trace ion extraction, and controllable costs, has attracted widespread attention.

[0004] ESIX technology operates under mild conditions, using electricity as the driving force. Besides the chemical or physical adsorption of the membrane material itself, the application of potential increases its adsorption and desorption of cations and anions, making it suitable for separating ions at low concentrations in solution. The separation process requires no chemical regeneration, avoiding secondary pollution from chemical regenerators. Applying this technology to the separation of bromine from oilfield brine hinges on developing a functional membrane material that is both electroactive and selectively adsorbs bromine ions. Electroactive materials can conduct both electrons and ions; by altering the redox state of the electroactive material, the insertion and removal of target ions can be achieved. However, while existing bromine extraction materials have demonstrated significant advantages, their large-scale application is limited by high preparation costs and complex synthesis processes. Summary of the Invention

[0005] To solve all or part of the above-mentioned technical problems, the present invention provides the following technical solutions: One objective of this invention is to provide an electroadsorption material for the electrochemical extraction of bromine, wherein the electroadsorption material is a membrane electrode prepared from NC-800 and PVDF. The mass ratio of the NC-800 nanocarbon material to PVDF is 1~50:0.1~5.

[0006] The porous structure and active sites on the surface of the electroadsorption material enable it to adsorb bromide ions, and the adsorption of bromine is promoted when an electric field is applied. The electroadsorption material exhibits a large adsorption capacity, a fast adsorption rate, and excellent selective adsorption for bromine, and its adsorption is unaffected by other anions in the sample. Furthermore, the composite material demonstrates good cycling stability and low solubility.

[0007] In some embodiments, according to BET testing, the specific surface area of ​​the electroadsorption material is 1.5 to 5 times that of the ZIF-8 precursor. The pure ZIF-8 precursor has a relatively smooth surface, resulting in poor conductivity and low adsorption efficiency when directly used as a bromine adsorption material. This invention discovers that calcining ZIF-8 at 800°C under a nitrogen atmosphere roughens the surface, increasing the specific surface area of ​​the material to more than 1.5 to 5 times that of the ZIF-8 precursor, thus providing a richer number of active sites for bromine capture and release.

[0008] In some embodiments, the particle size of the NC-800 cube is 50~500 nm.

[0009] Thermogravimetric analysis (TG test) showed that the initial weight loss temperature of the ZIF-8 precursor was 560℃, while that of the NC-800 was 106℃. This indicates that they possess heat resistance and can adapt to most brine temperature environments.

[0010] The second objective of this invention is to provide a method for preparing the aforementioned electroadsorption material, comprising: ZIF-8 precursor was synthesized using a room temperature stirring method; The prepared ZIF-8 was placed in a tube furnace and calcined at 800°C for 3 hours under nitrogen atmosphere to obtain NC-800 nano-carbon material. A film electrode containing the NC-800 nano-carbon material and PVDF was then prepared using a mechanical coating method.

[0011] In some embodiments, the mass ratio of NC-800 to PVDF in the NC-800 conductive substrate is 1~50:0.1~5.

[0012] In some embodiments, the ZIF-8 precursor is calcined at a temperature of 500~1200℃.

[0013] In some embodiments, the adsorption potential is 0.4~1.2V, and the adsorption equilibrium time is 60~300min.

[0014] In some embodiments, the room temperature stirring method includes: reacting a reaction system containing a zinc source and an imidazole ligand at room temperature, wherein the pH of the reaction system is 5-8, to obtain the ZIF-8 precursor.

[0015] In some embodiments, the concentration of the zinc source in the reaction system is 0.1~1 mol / L, and the concentration of the imidazole ligand is 0.4~4 mol / L.

[0016] In some embodiments, the zinc source includes Zn(CH3COOH)2, and the imidazole ligand includes 2-methylimidazole.

[0017] In some embodiments, the calcination temperature is 500~1200℃.

[0018] A third objective of this invention is to provide a bromine-active electrode, wherein the bromine-active electrode comprises the aforementioned electroadsorption material.

[0019] In some embodiments, the bromine active electrode includes an NC-800 conductive substrate, and the composite film layer includes an electroadsorption material, a conductive material, and a binder.

[0020] In some embodiments, the mass ratio of the electroadsorption material to the binder in the NC-800 conductive substrate is 1~50:0.1~5. For example, the electroadsorption material and binder are uniformly mixed according to the above mass ratio, and an appropriate amount of solvent is added to form a slurry. The slurry is then coated onto the conductive substrate and cured to form the composite film electrode. The slurry made from the electroadsorption material has good ductility, allowing for large-area and long-term use with small quantities. The electroadsorption material is low in cost and has good economic benefits, thus showing promising prospects for industrialization and commercialization.

[0021] In some embodiments, the adhesive includes one or more of polyvinylidene fluoride, polyacrylic acid, polymethacrylic acid, and polyvinyl alcohol, but is not limited thereto.

[0022] In some embodiments, the conductive substrate is made of one or more of carbon, titanium, and nickel, but is not limited thereto. For example, the conductive substrate may be carbon paper, carbon sheet, titanium sheet, nickel foam, etc.

[0023] The fourth objective of this invention is to provide a system for extracting bromine, comprising: a working electrode, a counter electrode, and a reference electrode, wherein the working electrode is the aforementioned bromine active electrode.

[0024] The fifth objective of this invention is to provide the application of the electroadsorption material, the bromine active electrode, or the bromine extraction system in the extraction of bromine from brine.

[0025] In some embodiments, the brine is oilfield brine. This invention reveals that the NC-800 electroadsorption material exhibits strong stability, and its bromide ion extraction is controlled by the applied redox potential, making it less susceptible to interference from other impurities in the sample. This makes it particularly suitable for bromide ion extraction from oilfield brine or other more extreme environments.

[0026] The sixth objective of this invention is to provide a method for extracting bromine from brine, using the aforementioned bromine extraction system, comprising: The ZIF-8 was calcined at 800°C under a nitrogen atmosphere to prepare the NC-800 film electrode.

[0027] The NC-800 bromine active electrode is placed in brine, and a voltage of 0.4-1.2V is applied to cause the bromine active electrode to adsorb bromide ions in the brine to achieve bromine extraction.

[0028] The method for extracting bromine from oilfield brine does not require acid or alkali washing to remove bromide ions. The adsorption and desorption of bromine can be achieved by applying voltage. The entire electro-adsorption process is simple, efficient, low-cost, and environmentally friendly.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects: the electro-adsorption material for bromine extraction prepared by the present invention has a large adsorption capacity, good cycle stability and excellent selective adsorption; the electro-adsorption material still has a certain adsorption capacity for solutions with bromide ion content below 100 mg / L. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 These are scanning electron microscope (SEM) images, elemental spectrum images, and transmission electron microscope (TEM) images of the NC-800 material prepared in one embodiment of the present invention. Figure 2 This is a flowchart of the material preparation and the extraction of bromide ions using a three-electrode system constructed in one embodiment of the present invention; Figure 3 This is a comparison of the adsorption performance of the bromine active electrode prepared in one embodiment of the present invention under voltage conditions of 0.4V, 0.6V, 0.8V and 1.0V, and the change of adsorption amount over time. Figure 4 This is a comparison chart of the adsorption capacity of the bromine active electrode prepared in one embodiment of the present invention at different pH values; Figure 5 This represents the change in adsorption capacity of a bromine-active electrode prepared according to an embodiment of the present invention after 10 cycles. Detailed Implementation

[0032] The technical solutions of the present invention will be described in detail below with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention. Specific functional details disclosed herein should not be construed as limiting, but are merely intended to form the basis of the claims and to teach those skilled in the art. Unless otherwise stated, The raw materials and reagents used in the following specific embodiments are all commercially available, and the detection and characterization methods used are conventional methods in the field. Example

[0033] 1.5 g of Zn(CH3COOH)2 was dissolved in 100 mL of methanol and stirred continuously for 1 h to obtain a Zn(CH3COOH)2 solution. Then, 3.36 g of 2-methylimidazole and 1.02 g of polyvinylpyrrolidone (PVP, K-30) were dissolved in 100 mL of methanol to obtain an imidazole solution. The imidazole solution was added dropwise to the Zn(CH3COOH)2 solution being stirred. After all the addition was completed, magnetic stirring was continued for 24 h. After the reaction was completed, the prepared ZIF-8 was repeatedly washed with methanol to remove residual ions, and the washed ZIF-8 was dried in a vacuum oven at 60°C for 12 h. The prepared ZIF-8 sample was ground into powder and then transferred into a tube furnace reaction chamber. A nitrogen atmosphere was first introduced into the tube furnace and maintained for 30 min to fully purge residual oxygen. Then, under continuous nitrogen protection, the system was heated to 800℃ at a heating rate of 5℃·min⁻¹ and carbonized at the target temperature for 3 h. After carbonization, the tube furnace was allowed to cool naturally to below 30℃, and the black powder product was removed. To remove residual zinc impurities from the product, the black powder was immersed in a 1 mol / L HCl aqueous solution and continuously stirred for acid washing. After acid washing, the sample was repeatedly washed with deionized water until the pH of the washing solution reached neutral. The washed product was transferred to an 80℃ constant-temperature drying oven and dried for 5 h to finally obtain the N-doped ZIF-8 derived carbon material NC-800. Take 0.8g of NC-800 powder and 0.1g of PVDF, mix thoroughly and grind for 1 hour. Add 4mL of N-methylpyrrolidone and continue grinding for 1 hour. After forming a smooth and uniform slurry, use a spatula to spread it on an area of ​​1cm². 2 The coating is applied to carbon paper and then dried in a vacuum oven at 90°C for 3 hours. Once the coating is completely dried, the NC-800 film is obtained.

[0034] Figure 1(ad) are scanning electron microscope (SEM) images of ZIF-8 prepared in this embodiment and of ZIF-8-derived carbon (NC-600, NC-800, NC-1000) film electrodes calcined at 600°C, 800°C, and 1000°C under a nitrogen atmosphere, respectively. Figure 1 (a) shows the microstructure of ZIF-8. Figure 1 (b), (c), and (d) show the microstructures of NC-600, NC-800, and NC-1000, respectively. At 1 μm, ZIF-8 exhibits a dodecahedral cubic structure. High-temperature calcination did not change its basic structure, and the volume of the material decreased significantly with increasing calcination temperature. Uncalcined ZIF-8 can be observed at the 100 nm scale. Figure 1 (a) The surface of the ZIF-8 cube is very smooth, while Figure 1 (c) The surface of NC-800 shows very obvious roughness and defects, which greatly increases the specific surface area of ​​the material and provides more active sites for the adsorption of bromide ions. Figure 1 (e) is the elemental analysis diagram of NC-800. It can be observed that NC-800 is mainly composed of carbon and nitrogen elements, and it can be seen that bromine was successfully adsorbed after adsorption. Figure 1 (f) are transmission electron micrographs of ZIF-8 and NC-800. NC-800 is significantly smaller in size and has a noticeably rougher surface than ZIF-8. The rougher surface and increased surface defects of NC-800, along with the richer active sites, are all conducive to the adsorption of bromide ions.

[0035] According to thermogravimetric analysis, the ZIF-8 material begins to lose a significant amount of weight at 570℃ and basically stops losing weight at 1000℃. Therefore, 600℃, 800℃, and 1000℃ were selected as the calcination and carbonization temperatures, respectively. Adsorption experiments and characterization results show that NC-800 has good performance and good adsorption capacity for bromide ions.

[0036] Adsorption-desorption operations were performed using an electrochemical workstation in a three-electrode system. The bromine active electrode prepared above was used as the working electrode, a platinum wire as the counter electrode, and a saturated calomel electrode as the reference electrode. The NC-800 membrane electrode was placed in a bromine-containing solution with a concentration of 200 mg / L as the working electrode, and adsorption tests were performed under voltage conditions of 0.4 V, 0.6 V, 0.8 V, and 1.0 V. Figure 2 This is a flowchart of the material synthesis and adsorption / extraction of bromide ions.

[0037] Figure 3 This describes the adsorption performance of the bromine active electrode under different voltage conditions in this embodiment. Figure 3It can be seen that the bromine active electrode has the ability to adsorb bromide ions within a voltage range of 0.4~1.0V, and the adsorption performance is better at 1.0V. At a bromide ion concentration of 200mg / L, the adsorption capacity can reach 115.65mg / g after 240min of adsorption. This bromine active electrode has a high adsorption rate (the adsorption data shown in Table 1 refer to the adsorption amount of the membrane electrode after 240min), such as... Figure 4 As shown, the maximum adsorption capacity can be achieved at a bromide ion concentration of 200 mg / L and a pH of 7, at which point the adsorption capacity is 115.65 mg / g, which is significantly higher than that required by conventional adsorbents.

[0038] Table 1. Bromine adsorption performance of the bromine active electrode in Example 1 under different voltage conditions. Voltage Maximum adsorption capacity (mg / g) Adsorption rate (min) Cyclic stability 0.4V 47.1 240 The adsorption capacity is stable within 7 cycles. 0.6V 60.45 240 The adsorption capacity is stable within 7 cycles. 0.8V 70.2 240 The adsorption capacity is stable within 7 cycles. 1.0V 115.65 240 The adsorption capacity is stable within 7 cycles. Using the bromine-active electrode prepared in Example 1, the adsorption capacity changed after 7 cycles of adsorption at a voltage of 1.0 V, a bromide ion concentration of 200 mg / L, and an adsorption time of 240 min. The experimental results show that within 7 cycles, the adsorption capacity of the membrane electrode for bromide ions does not fluctuate significantly, indicating good cyclic stability of the membrane electrode. Example

[0039] 3.00 g of Zn(CH3COOH)2 was dissolved in 100 mL of methanol and stirred continuously for 1 h to obtain a Zn(CH3COOH)2 solution. Then, 6.72 g of 2-methylimidazole and 2.04 g of polyvinylpyrrolidone (PVP, K-30) were dissolved in 100 mL of methanol to obtain an imidazole solution. The imidazole solution was added dropwise to the Zn(CH3COOH)2 solution being stirred. After all the addition was completed, magnetic stirring was continued for 24 h. After the reaction was completed, the prepared ZIF-8 was repeatedly washed with methanol to remove residual ions, and the washed ZIF-8 was dried in a vacuum oven at 60°C for 12 h. The prepared ZIF-8 sample was ground into powder and then transferred into a tube furnace reaction chamber. A nitrogen atmosphere was first introduced into the tube furnace and maintained for 30 min to fully purge residual oxygen. Then, under continuous nitrogen protection, the system was heated to 800℃ at a heating rate of 8℃·min⁻¹ and carbonized at the target temperature for 5 h. After carbonization, the tube furnace was allowed to cool naturally to below 30℃, and the black powder product was removed. To remove residual zinc impurities from the product, the black powder was immersed in a 1 mol / L HCl aqueous solution and continuously stirred for acid washing. After acid washing, the sample was repeatedly washed with deionized water until the pH of the washing solution reached neutral. The washed product was transferred to an 80℃ constant-temperature drying oven and dried for 6 h to finally obtain the N-doped ZIF-8 derived carbon material NC-800. Take 0.8g of NC-800 powder and 0.1g of PVDF, mix thoroughly and grind for 1 hour. Add 4mL of N-methylpyrrolidone and continue grinding for 1 hour. After forming a smooth and uniform slurry, use a spatula to spread it on an area of ​​1cm². 2 The coating is applied to carbon paper and then dried in a vacuum oven at 90°C for 3 hours. Once the coating is completely dried, the NC-800 film is obtained.

[0040] The bromine active electrode prepared in Example 2 was tested using the same method as in Example 1. The adsorption capacity, adsorption rate and cycle stability of the bromine active electrode prepared in this example were comparable to those in Example 1. Example

[0041] 1.50 g of Zn(CH3COOH)2 was dissolved in 100 mL of methanol and stirred continuously for 1 h to obtain a Zn(CH3COOH)2 solution. Then, 3.36 g of 2-methylimidazole and 1.02 g of polyvinylpyrrolidone (PVP, K-30) were dissolved in 100 mL of methanol to obtain an imidazole solution. The imidazole solution was added dropwise to the Zn(CH3COOH)2 solution being stirred. After all the addition was completed, magnetic stirring was continued for 24 h. After the reaction was completed, the prepared ZIF-8 was repeatedly washed with methanol to remove residual ions, and the washed ZIF-8 was dried in a vacuum oven at 60°C for 12 h. The prepared ZIF-8 sample was ground into powder and then transferred into a tube furnace reaction chamber. A nitrogen atmosphere was first introduced into the tube furnace and maintained for 30 min to fully purge residual oxygen. Then, under continuous nitrogen protection, the system was heated to 800℃ at a heating rate of 5℃·min⁻¹ and carbonized at the target temperature for 2 h. After carbonization, the tube furnace was allowed to cool naturally to below 30℃, and the black powder product was removed. To remove residual zinc impurities from the product, the black powder was immersed in a 1 mol / L HCl aqueous solution and continuously stirred for acid washing. After acid washing, the sample was repeatedly washed with deionized water until the pH of the washing solution reached neutral. The washed product was transferred to a 100℃ constant temperature drying oven and dried for 10 h to finally obtain the N-doped ZIF-8 derived carbon material NC-800. Take 0.8g of NC-800 powder and 0.1g of PVDF, mix thoroughly and grind for 1 hour. Add 4mL of N-methylpyrrolidone and continue grinding for 1 hour. After forming a smooth and uniform slurry, use a spatula to spread it on an area of ​​1cm². 2 The coating is applied to carbon paper and then dried in a vacuum oven at 90°C for 3 hours. Once the coating is completely dried, the NC-800 film is obtained.

[0042] The bromine active electrode prepared in Example 3 was tested using the same method as in Example 1. The adsorption capacity, adsorption rate and cycle stability of the bromine active electrode prepared in this embodiment were comparable to those in Example 1.

[0043] Comparative Example 1 uses ZIF-8 alone to prepare a bromine active membrane electrode. The NC-800 membrane electrode is the same as the NC-800 bromine active membrane electrode prepared in Example 1. The rest of the process is the same as in Example 1.

[0044] By comparing Example 1 and Comparative Example 1, it was found that the bromine active electrode based on NC-800 membrane exhibited better conductivity and adsorption capacity than the simple ZIF-8 bromine active membrane electrode. Under the same adsorption conditions, the bromine active electrode of Example 1 had an adsorption capacity that was more than 6 times higher and an adsorption rate that was 60% higher than that of Comparative Example 1.

[0045] The only difference between Comparative Example 2 and Example 1 is that Comparative Example 2 uses a bromine-active membrane electrode prepared from ZIF-8 derived carbon (hereinafter referred to as NC-600) calcined at 600°C under a nitrogen atmosphere.

[0046] This invention uses the bromine-active electrodes from Examples 1, 1, and 2 above to test real brine samples (Br). - Bromine extraction was tested at a concentration of approximately 200 mg / L. Under the same conditions and with a potential of 1.0 V, the adsorption capacity of ZIF-8 alone in Comparative Example 1 was 19.27 mg / g, the adsorption capacity of the NC-600 membrane electrode alone in Comparative Example 2 was 88.59 mg / g, while the adsorption capacity of the bromine active electrode in Example 1 was 115.65 mg / g. This indicates that calcination of ZIF-8 significantly improves its conductivity, which is beneficial for electrochemical adsorption. Calcination under a nitrogen atmosphere introduces nitrogen-active sites, greatly enhancing the adsorption of bromide ions by NC-800. The adsorption capacity of ZIF-8 alone is much smaller than that of the NC-800 membrane. This is because the conductivity of the ZIF-8 electrode alone is extremely poor. Calcination and carbonization significantly improve the conductivity of the bromine active electrode. Furthermore, the roughness of NC-800 is much greater than that of ZIF-8, which provides abundant active sites for the adsorption of bromide ions.

[0047] All aspects, embodiments, features, and examples of this invention are to be regarded as illustrative in all respects and are not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0048] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0049] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is used to distinguish one element from another.

Claims

1. An electrosorptive material for electrochemical extraction of bromine, characterized in that, The electrode includes: The mass ratio of the NC-800 to the PVDF is 1-50:0.1-5.

2. The electrosorptive material of claim 1, wherein: According to the BET test, the specific surface area of the electro-adsorbing material is 1.5-5 times of that of the ZIF-8; And / or, the particle size of the NC-800 cubic is 50-500 nm; And / or, according to the thermal gravimetric analysis, the temperature at which the ZIF-8 precursor starts to lose weight greatly is 570℃, and the temperature at which the NC-800 starts to lose weight greatly is 106℃.

3. The method of producing an electrosorptive material as claimed in claim 1 or 2, characterized in that, The method includes: The ZIF-8 precursor is synthesized by using the room temperature stirring method; The prepared ZIF-8 is placed in a tube furnace and calcined at 800℃ for 3h under nitrogen atmosphere to obtain the NC-800 nanocarbon material.

4. The method of claim 3, wherein: The mass of the NC-800 nanocarbon and the PVDF in the NC-800 electrode is 1-50:0.1-5g; And / or, the temperature selected when the ZIF-8 precursor is calcined is 500-1200℃; And / or, the adsorption potential is 0.4-1.2V, and the adsorption equilibrium time is 60-300min.

5. A bromine-active electrode, characterized in that The electro-adsorbing material of claim 1 or 2.

6. The bromine-active electrode according to claim 5, characterized by the fact that: The bromine-active electrode is the NC-800 nanocarbon material, and the composite film layer includes the electro-adsorbing material of claim 1 or 2 and a binder.

7. The bromo-active electrode of claim 6, wherein: The mass ratio of the electro-adsorbing material to the binder in the conductive substrate is 1-50:0.1-5; And / or, the temperature selected when the ZIF-8 precursor is calcined is 500-1200℃; And / or, the binder includes one or a combination of polyvinylidene fluoride, polyacrylic acid, polymethacrylic acid, and polyvinyl alcohol; And / or, the substrate material coated by the conductive film preparation material includes one or a combination of carbon, titanium, and nickel.

8. A system for extracting bromine, characterized by The electrode includes: The working electrode is the bromine-active electrode of any one of claims 5-7.

9. The use of the electro-adsorbing material of claim 1 or 2, the bromine-active electrode of any one of claims 5-7, or the system for extracting bromine of claim 8 in extracting bromine elements from brine.

10. A method of extracting bromine from oilfield brines, characterized in that, The system for extracting bromine of claim 8 includes: The bromine-active electrode is placed in the oilfield brine, and a voltage of 0.4-1.2V is applied to make the bromine-active electrode adsorb bromide ions in the brine to achieve the extraction of bromine.

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