A sandwich-structured anode composite film, its preparation method and application

Abstract

This invention belongs to the field of brine bromine extraction technology, specifically relating to a sandwich-structured anode composite membrane, its preparation method, and its application in electro-controlled ion exchange bromine extraction. The sandwich-structured anode composite membrane comprises a conductive substrate layer, an electron shuttle layer, and an electro-controlled adsorption layer sequentially disposed on the conductive substrate layer; the conductive substrate layer is a porous titanium plate; the electron shuttle layer is composed of Ti3C2 nanosheets and a binder; the electro-controlled adsorption layer is composed of rare earth bromide oxide nanosheets and a binder; the rare earth bromide oxide nanosheets are LaOBr nanosheets or CeOBr nanosheets. The anode composite membrane has a sandwich structure, with synergistic effects between the composite layers, significantly enhancing bromide ion selectivity and solving the problem of poor selectivity in traditional materials; it also maintains excellent adsorption performance and stability for high-chlorine brine.

Description

Technical Field

[0001] This invention belongs to the field of brine bromine extraction technology, specifically relating to a sandwich-structured anode composite membrane, its preparation method, and its application in electro-controlled ion exchange bromine extraction. Background Technology

[0002] Bromine and bromide products are in high demand in agriculture, medicine, electronics, and other fields. Oil and gas field brine, as an important bromine resource, has a bromide ion concentration of 200-1000 mg / L, indicating huge development potential. Currently, electro-controlled ion exchange technology has attracted attention due to its environmental friendliness and ease of operation, but it still faces key challenges in practical applications: poor bromide ion selectivity in high-chlorine environments, severe chloride ion interference, low bromine / chlorine separation efficiency, and difficulty in bromide ion enrichment, resulting in bromine purity and conversion rates that cannot meet industrial requirements.

[0003] Currently, anolyte membrane structures are limited, making it difficult to simultaneously achieve optimal adsorption selectivity, electron transport velocity, and mass transfer rate. Furthermore, electrode material preparation methods often employ techniques such as blade coating, coating, and vacuum filtration, which suffer from defects like weak membrane bonding and poor thickness uniformity, affecting the mass transfer efficiency and stability of electro-controlled ion exchange performance. Therefore, developing electrode composite membrane materials and preparation processes with high selectivity and high stability is of great significance for improving the bromine extraction efficiency of high-chlorine brine and reducing production costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the first objective of this invention is to provide a sandwich-structured anode composite membrane that significantly enhances the selective adsorption capacity of bromide ions in high-chlorine brine and improves the bromine-chlorine separation efficiency. The second objective is to provide a method for preparing the anode composite membrane. The third objective is to provide an application of the anode composite membrane in bromine extraction in electro-controlled ion exchange for high-chlorine brine, exhibiting good stability and high selectivity.

[0005] A sandwich-structured anode composite film includes a conductive substrate layer, and an electron shuttle layer and an electro-controlled adsorption layer sequentially disposed on the conductive substrate layer; The conductive substrate layer is a porous titanium plate; The electron shuttle layer is composed of Ti3C2 nanosheets and a binder; The electro-adsorption layer is composed of rare earth bromine oxide nanosheets and a binder; the rare earth bromine oxide nanosheets are LaOBr nanosheets or CeOBr nanosheets.

[0006] Preferably, the mass ratio of the rare earth bromine oxide nanosheets to the Ti3C2 nanosheets is 1~3:1.

[0007] Preferably, the porous titanium plate has a pore size of 100~500 nm, a porosity of 40~60%, and a thickness of 1.5~2 mm.

[0008] Preferably, the binder content in both the electron shuttle layer and the electro-adsorption layer is 6-20%.

[0009] Preferably, the adhesive is polytetrafluoroethylene.

[0010] Preferably, the thickness of the Ti3C2 nanosheets is 1~5 nm, the thickness of the rare earth bromine oxide nanosheets is ≤3 nm, and the total thickness of the electron shuttle layer and the electro-controlled adsorption layer is 10~50 μm.

[0011] More preferably, the total thickness of the electron shuttle layer and the electronically controlled adsorption layer is 20~25 μm.

[0012] The method for preparing the sandwich-structured anode composite film includes the following steps: (1) Preparation of rare earth bromine oxide nanosheets: Dissolve rare earth metal nitrates and polyvinylpyrrolidone in water, add KBr solution dropwise, stir the reaction at room temperature for 30-60 min, wash the product with water and ethanol, and freeze dry under vacuum to obtain rare earth bromine oxide nanosheets. (2) Preparation of rare earth bromine oxide nanoparticle paste: The rare earth bromine oxide nanosheets and binder are added to ethanol and ultrasonically dispersed for 40-60 min to obtain rare earth bromine oxide nanoparticle paste; (3) Preparation of Ti3C2 nanosheet nanoparticle paste: Ti3C2 nanosheets and binder are added to ethanol and ultrasonically dispersed for 40-60 min to obtain Ti3C2 nanosheet nanoparticle paste; (4) Spraying and forming: Using a nano-slurry pneumatic spraying machine, Ti3C2 nano-slurry and rare earth bromine oxide nano-slurry are sprayed onto the surface of the porous titanium plate layer by layer and then dried.

[0013] Preferably, the stirring speed in step (i) is 600~1000 rpm, and the drying conditions in step (4) are drying at 60~100℃ for 30~60 min.

[0014] Preferably, the operating conditions of the nano-slurry pneumatic spraying machine are as follows: spraying air pressure is 0.3~0.6 MPa, and spraying distance is 5~15 cm.

[0015] Preferably, the mass ratio of the rare earth metal nitrate to polyvinylpyrrolidone is 10~17.5∶1; the molar ratio of the rare earth metal nitrate to KBr in the KBr solution is 0.8~1.2∶1.

[0016] A method for extracting bromine from bromine-containing high-chlorine brine based on electro-controlled ion exchange includes the following steps: (i) Separation of bromine: Using the sandwich-structured anode composite membrane as the anode and the titanium mesh as the cathode, bromine-containing high-chlorine brine is passed into the electrolytic cell, and hydrochloric acid solution is passed into the cathode cell at the same flow rate. A voltage of 0.8~1.4 V is applied, and adsorption by electro-controlled ion exchange is carried out at room temperature and pressure to achieve selective adsorption and separation of bromine ions. (II) Enrichment of bromine: After adsorbing bromide ions, the brine in the electrolytic cell is discharged and pure water is introduced for analysis. The anode and cathode in step (I) are interchanged, and a voltage of 1.4~2 V is applied. Desorption by electro-controlled ion exchange is carried out at room temperature and pressure to achieve the enrichment of bromide ions.

[0017] Preferably, the pH value of the hydrochloric acid solution is 1.5 to 2.

[0018] Preferably, the adsorption time in step (i) is 60-90 min; the desorption time in step (ii) is 60-90 min.

[0019] Advantages of this invention: 1. The anode composite membrane provided by the present invention has a sandwich structure, with a porous titanium plate as a conductive substrate. LaOBr and CeOBr have specific adsorption sites for bromide ions, Ti3C2 improves conductivity and mass transfer rate, and a synergistic effect is formed between the composite layers, which significantly enhances the selectivity of bromide ions. The bromine-chlorine separation factor is ≥130, which solves the problem of poor selectivity of traditional materials. 2. Prepared using a nano-slurry pneumatic spraying process, the film layer is firmly bonded to the substrate, has good thickness uniformity, controllable pore structure, low electrode resistivity, fast ion migration rate during electro-controlled ion exchange, and high bromide ion adsorption capacity. 3. The preparation process does not require high temperature and high pressure, the reaction conditions are mild, the raw materials are readily available, the production cost is low, and it is suitable for industrial-scale promotion and application; 4. It maintains excellent adsorption performance and stability even for high-chlorine brines with chloride ion concentrations of 20~30 g / L, and can be directly applied to bromine extraction processes in complex systems such as oil and gas field brines. Attached Figure Description

[0020] Figure 1 A schematic diagram of the cross-sectional structure of the sandwich-structured anode composite film prepared according to the present invention; Figure 2 This is a schematic diagram of the device structure used in this invention; Figure 3 The adsorption rate curves are shown for different bromide ion concentrations. Among them, 1-electro-controlled adsorption layer, 2-electron shuttle layer, 3-conductive substrate layer, 4-anode, 5-cathode. Detailed Implementation

[0021] Example 1: A sandwich-structured anode composite membrane, the structural schematic diagram is shown below. Figure 1 As shown, it includes a conductive substrate layer (3), and an electron shuttle layer (2) and an electro-adsorption layer (1) sequentially disposed on the conductive substrate layer (3). The conductive substrate layer (3) is a porous titanium plate; the porous titanium plate has a pore size of 300 nm, a porosity of 50%, and a thickness of 1.8 mm; The electron shuttle layer (2) is composed of Ti3C2 nanosheets and a binder, wherein the binder accounts for 13% by weight and the thickness of the Ti3C2 nanosheets is 3 nm. The electro-adsorption layer (1) is composed of rare earth bromine oxide nanosheets and a binder, wherein the binder accounts for 6.98% by weight; the rare earth bromine oxide nanosheets are LaOBr nanosheets with a thickness of 2.8 nm; The mass ratio of the rare earth bromide nanosheets to the Ti3C2 nanosheets is 2:1; The total thickness of the electron shuttle layer (2) and the electro-adsorption layer (1) is 25 μm.

[0022] The method for preparing the sandwich-structured anode composite film includes the following steps: (1) Preparation of rare earth bromide nanosheets: 1.0 mmol (0.4330 g) of La(NO3)3·6H2O and 30 mg of polyvinylpyrrolidone were dissolved in 50 mL of ultrapure water to obtain a La(NO3)3·6H2O solution; 1.0 mmol of KBr was weighed and dissolved in 20 mL of ultrapure water to obtain a KBr solution; the KBr solution was slowly added dropwise to the La(NO3)3·6H2O solution, and the reaction was stirred at room temperature for 40 min at a stirring speed of 800 rpm. The product was washed three times each with ultrapure water and ethanol, and then freeze-dried under vacuum to obtain rare earth bromide nanosheets, which were LaOBr nanosheets with a thickness of 2.8 nm. (2) Preparation of rare earth bromide oxide nanoparticles: Weigh 0.2g of the rare earth bromide oxide nanosheets and 0.015g of the binder polytetrafluoroethylene and add them to 50 mL of ethanol. Disperse by ultrasonication for 50 min to obtain rare earth bromide oxide nanoparticles; (3) Preparation of Ti3C2 nanosheet nanoparticle paste: 0.1 g Ti3C2 nanosheets and 0.015 g binder polytetrafluoroethylene were added to 50 mL ethanol and ultrasonically dispersed for 50 min to obtain Ti3C2 nanosheet nanoparticle paste; (4) Spray coating: Ti3C2 nano-slurry and rare earth bromine oxide nano-slurry were sequentially sprayed onto the surface of the porous titanium plate using a nano-slurry pneumatic spraying machine. The spraying pressure was 0.4 MPa, the spraying distance was 15 cm, and the film was dried at 80℃ for 40 min to obtain the anode composite film. The total thickness of the electron shuttle layer and the electro-adsorption layer in the anode composite film was 25 μm, the average pore size of the electron shuttle layer and the electro-adsorption layer was 40 nm, and the resistivity was 1.8 × 10⁻⁶. -3 Ω·m, the permeability to 10 mM KNO3 electrolyte solution is 250 h. -1 ·m -2 ·bar -1 .

[0023] A method for extracting bromine from bromine-containing high-chlorine brine based on electro-controlled ion exchange, wherein the reaction apparatus is as follows: Figure 2 As shown, at normal temperature and pressure, simulated high-chlorine brine with a bromide ion concentration of 1000 mg / L and a chloride ion concentration of 30 g / L is introduced into the electrolytic cell at a flow rate of 2 mL / min. Hydrochloric acid solution with a pH of 2 is introduced into the cathode cell at the same flow rate. The sandwich structure anode composite membrane is used as the anode (4), and the titanium mesh is used as the cathode (5). A voltage of 1.2 V is applied for electro-controlled ion exchange. After adsorption, the brine in the electrolytic cell is discharged, and pure water is introduced for desorption. The anode and cathode are interchanged, and a voltage of 1.6 V is applied to carry out desorption by electro-controlled ion exchange at room temperature and pressure to achieve the enrichment of bromide ions. Adsorption results for different time periods were obtained by varying the concentration of bromide ions in the simulated high-chlorine brine (including 200 mg / L, 400 mg / L, and 800 mg / L). Figure 3 As shown in (a), for chlorinated brine with a bromide concentration of 1000 mg / L, after the first adsorption reaction of 60 min, the bromide adsorption capacity of the anode composite membrane composite material is 131.6 mg / g (i.e., the amount of bromide adsorbed per gram of anode composite membrane), and the bromine-chlorine separation factor is 126.8; after the adsorption reaction of 90 min, the bromide adsorption capacity is 152.24 mg / g. For simulated high-chlorine brine with a bromide concentration of 1000 mg / L and a chloride concentration of 30 g / L, after 20 consecutive cycles of adsorption and desorption (with an adsorption and desorption time of 90 min in each cycle), the bromide adsorption capacity remained above 150 mg / g (composite membrane), the desorption efficiency reached over 95%, and the stability was good.

[0024] Example 2: The rare earth bromine oxide nanosheets are CeOBr nanosheets with a thickness of 2.5 nm. The rare earth metal nitrate used in the preparation is 1.0 mmol (0.4342 g) Ce(NO3)3·6H2O. The rest is the same as in Example 1. Testing revealed that the total thickness of the electron shuttle layer and the electrostatic adsorption layer in the anode composite film is 25 μm, the average pore size of the electron shuttle layer and the electrostatic adsorption layer is 42 nm, and the resistivity is 1.9 × 10⁻⁶. -3 The permeability to a 10 mM KNO3 electrolyte solution is 243 hΩ·m. -1 ·m -2 ·bar -1 ; The concentration of bromide ions in the simulated high-chlorine brine was varied (including 200 mg / L, 400 mg / L, and 800 mg / L), and the adsorption results are shown in [the table below]. Figure 3 (b) For chlorinated brine with a bromide concentration of 1000 mg / L, after the first adsorption reaction of 60 min, the bromide adsorption capacity of the anode composite membrane composite material was 122.4 mg / g (i.e., the amount of bromide adsorbed per gram of anode composite membrane), and the bromine-chlorine separation factor was 125.2; after the adsorption reaction of 90 min, the bromide adsorption capacity was 153.61 mg / g. For simulated high-chlorine brine with a bromide concentration of 1000 mg / L and a chloride concentration of 30 g / L, after 20 consecutive cycles of adsorption and desorption (with an adsorption and desorption time of 90 min in each cycle), the bromide adsorption capacity remained above 150 mg / g (composite membrane), the desorption efficiency reached over 94%, and the stability was good.

[0025] Example 3: A sandwich structure anode composite film, comprising a conductive substrate layer, and an electron shuttle layer and an electro-controlled adsorption layer sequentially disposed on the conductive substrate layer; The conductive substrate layer is a porous titanium plate; the porous titanium plate has a pore size of 200 nm, a porosity of 45%, and a thickness of 1.5 mm; The electron shuttle layer is composed of Ti3C2 nanosheets and a binder, wherein the binder accounts for 6.25% by weight and the thickness of the Ti3C2 nanosheets is 2 nm. The electro-adsorption layer is composed of rare earth bromide nanosheets and a binder, wherein the binder accounts for 6.25% by weight; the rare earth bromide nanosheets are LaOBr nanosheets with a thickness of 2.5 nm; The mass ratio of the rare earth bromide nanosheets to the Ti3C2 nanosheets is 1:1; The total thickness of the electron shuttle layer and the electro-adsorption layer is 20 μm.

[0026] The method for preparing the sandwich-structured anode composite film includes the following steps: (1) Preparation of rare earth bromide nanosheets: 0.8 mmol (0.3464 g) of La(NO3)3·6H2O and 20 mg of polyvinylpyrrolidone were dissolved in 40 mL of ultrapure water to obtain La(NO3)3·6H2O solution; 1.0 mmol of KBr was weighed and dissolved in 15 mL of ultrapure water to obtain KBr solution; the KBr solution was slowly added dropwise to the La(NO3)3·6H2O solution, and the reaction was stirred at room temperature for 30 min at a stirring speed of 600 rpm. The product was washed three times each with ultrapure water and ethanol, and then freeze-dried under vacuum to obtain rare earth bromide nanosheets, which were LaOBr nanosheets with a thickness of 2.5 nm. (2) Preparation of rare earth bromine oxide nanoparticles: Weigh 0.3 g of the rare earth bromine oxide nanosheets and 0.02 g of the binder polytetrafluoroethylene and add them to 60 mL of ethanol. Disperse by ultrasonication for 40 min to obtain rare earth bromine oxide nanoparticles; (3) Preparation of Ti3C2 nanosheet nanoparticle paste: 0.3 g Ti3C2 nanosheets and 0.02 g binder polytetrafluoroethylene were added to 60 mL ethanol and ultrasonically dispersed for 40 min to obtain Ti3C2 nanosheet nanoparticle paste; (4) Spraying and forming: Using a nano-slurry pneumatic spraying machine, Ti3C2 nano-slurry and rare earth bromine oxide nano-slurry are sequentially sprayed onto the surface of the porous titanium plate layer by layer. The spraying air pressure is 0.3 MPa, the spraying distance is 12 cm, and the film is dried at 70℃ for 30 min to obtain the anodic composite film. Testing revealed that the total thickness of the electron shuttle layer and the electrostatic adsorption layer in the anode composite film is 20 μm, the average pore size of the electron shuttle layer and the electrostatic adsorption layer is 30 nm, and the resistivity is 1.5 × 10⁻⁶. -3 The permeability to a 10 mM KNO3 electrolyte solution is 280 hΩ·m. -1 ·m -2 ·bar -1 .

[0027] A method for extracting bromine from bromine-containing high-chlorine brine based on electro-controlled ion exchange involves, at room temperature and pressure, introducing simulated high-chlorine brine with a bromide ion concentration of 200 mg / L and a chloride ion concentration of 20 g / L into an electrolytic cell at a flow rate of 1.5 mL / min, and introducing a hydrochloric acid solution with a pH of 1.5 into a cathode cell at the same flow rate. The sandwich-structured anode composite membrane is used as the anode, and a titanium mesh is used as the cathode. Electro-controlled ion exchange is performed by applying a voltage of 1.0 V. After adsorption, the brine in the electrolytic cell is discharged, and pure water is introduced for desorption. The anode and cathode are interchanged, and a voltage of 1.6 V is applied to carry out desorption by electro-controlled ion exchange at room temperature and pressure to achieve the enrichment of bromide ions. After 90 min of the initial adsorption reaction, the anode composite membrane composite material adsorbed 134.2 mg / g of bromide ions (i.e., the amount of bromide ions adsorbed per gram of anode composite membrane), and the bromine-chlorine separation factor was 112.3. After 20 cycles of adsorption and desorption (each cycle lasting 90 min), the bromide ion adsorption capacity remained above 130 mg / g (composite membrane), the desorption efficiency reached over 93%, and the stability was good.

[0028] Example 4: The rare earth bromine oxide nanosheets are CeOBr nanosheets with a thickness of 2.6 nm. The rare earth metal nitrate used in the preparation is 1.0 mmol (0.3474 g) Ce(NO3)3·6H2O. The rest is the same as in Example 3. Testing revealed that the total thickness of the electron shuttle layer and the electrostatic adsorption layer in the anode composite film is 20 μm, the average pore size of the electron shuttle layer and the electrostatic adsorption layer is 32 nm, and the resistivity is 1.5 × 10⁻⁶. -3 The permeability to a 10 mM KNO3 electrolyte solution is 275 hΩ·m. -1 ·m -2 ·bar -1 ; After 90 min of the initial adsorption reaction, the anode composite membrane composite material had an adsorption capacity of 131.5 mg / g for bromide ions and a bromine-chlorine separation factor of 110.2. After 20 consecutive cycles of adsorption and desorption (each cycle lasting 90 min), the bromide ion adsorption capacity remained above 130 mg / g (composite membrane), the desorption efficiency reached over 92%, and the stability was good.

[0029] Example 5: A sandwich structure anode composite film, comprising a conductive substrate layer, and an electron shuttle layer and an electro-controlled adsorption layer sequentially disposed on the conductive substrate layer; The conductive substrate layer is a porous titanium plate; the porous titanium plate has a pore size of 100 nm, a porosity of 40%, and a thickness of 1.5 mm; The electron shuttle layer is composed of Ti3C2 nanosheets and a binder, wherein the binder accounts for 6% by weight and the thickness of the Ti3C2 nanosheets is 1 nm. The electro-adsorption layer is composed of rare earth bromide nanosheets and a binder, wherein the binder accounts for 20% by weight; the rare earth bromide nanosheets are LaOBr nanosheets with a thickness of 2.2 nm; The mass ratio of the rare earth bromide nanosheets to the Ti3C2 nanosheets is 3:1; the total thickness of the electron shuttle layer and the electro-controlled adsorption layer is 25 μm. The method for preparing the sandwich-structured anode composite film includes the following steps: (1) Preparation of rare earth bromide nanosheets: 1.0 mmol (0.4330 g) of La(NO3)3·6H2O and 43.3 mg of polyvinylpyrrolidone were dissolved in 50 mL of ultrapure water to obtain a La(NO3)3·6H2O solution; 1.2 mmol of KBr was weighed and dissolved in 20 mL of ultrapure water to obtain a KBr solution; the KBr solution was slowly added dropwise to the La(NO3)3·6H2O solution, and the reaction was stirred at room temperature for 30 min at a stirring speed of 1000 rpm. The product was washed three times each with ultrapure water and ethanol, and then freeze-dried under vacuum to obtain rare earth bromide nanosheets, which were LaOBr nanosheets with a thickness of 2.2 nm. (2) Preparation of rare earth bromine oxide nanoparticles: Weigh 0.2 g of the rare earth bromine oxide nanosheets and 0.05 g of the binder polytetrafluoroethylene and add them to 50 mL of ethanol. Disperse by ultrasonication for 60 min to obtain rare earth bromine oxide nanoparticles; (3) Preparation of Ti3C2 nanosheet nanoparticle paste: 0.067 g Ti3C2 nanosheets and 0.0043 g polytetrafluoroethylene binder were added to 50 mL ethanol and ultrasonically dispersed for 60 min to obtain Ti3C2 nanosheet nanoparticle paste; (4) Spray coating: Using a nano-slurry pneumatic sprayer, Ti3C2 nano-slurry and rare earth bromine oxide nano-slurry were sequentially sprayed layer by layer onto the surface of the porous titanium plate. The spraying pressure was 0.3 MPa, the spraying distance was 5 cm, and the film was dried at 60℃ for 60 min to obtain the anode composite film. Testing showed that the total thickness of the electron shuttle layer and the electro-adsorption layer in the anode composite film was 25 μm, the average pore size of the electron shuttle layer and the electro-adsorption layer was 20 nm, and the resistivity was 2.0 × 10⁻⁶. -3 The permeability to a 10 mM KNO3 electrolyte solution is 220 hΩ·m. -1 ·m -2 ·bar -1 .

[0030] Example 6: A sandwich structure anode composite film, comprising a conductive substrate layer, and an electron shuttle layer and an electro-controlled adsorption layer sequentially disposed on the conductive substrate layer; The conductive substrate layer is a porous titanium plate; the porous titanium plate has a pore size of 500 nm, a porosity of 60%, and a thickness of 2 mm; The electron shuttle layer is composed of Ti3C2 nanosheets and a binder, wherein the binder accounts for 20% by weight and the thickness of the Ti3C2 nanosheets is 5 nm. The electro-adsorption layer is composed of rare earth bromide nanosheets and a binder, wherein the binder accounts for 6.1% by weight; the rare earth bromide nanosheets are LaOBr nanosheets with a thickness of 2.9 nm; The mass ratio of the rare earth bromide nanosheets to the Ti3C2 nanosheets is 2:1; the total thickness of the electron shuttle layer and the electro-controlled adsorption layer is 25 μm. The method for preparing the sandwich-structured anode composite film includes the following steps: (1) Preparation of rare earth bromide nanosheets: 1.0 mmol (0.4330 g) of La(NO3)3·6H2O and 30 mg of polyvinylpyrrolidone were dissolved in 50 mL of ultrapure water to obtain a La(NO3)3·6H2O solution; 1.0 mmol of KBr was weighed and dissolved in 20 mL of ultrapure water to obtain a KBr solution; the KBr solution was slowly added dropwise to the La(NO3)3·6H2O solution, and the reaction was stirred at room temperature for 60 min at a stirring speed of 800 rpm. The product was washed three times each with ultrapure water and ethanol, and then freeze-dried under vacuum to obtain rare earth bromide nanosheets, which were LaOBr nanosheets with a thickness of 2.9 nm. (2) Preparation of rare earth bromide oxide nanoparticles: Weigh 0.2g of the rare earth bromide oxide nanosheets and 0.013g of the binder polytetrafluoroethylene and add them to 50 mL of ethanol. Disperse by ultrasonication for 40 min to obtain rare earth bromide oxide nanoparticles; (3) Preparation of Ti3C2 nanosheet nanoparticle paste: 0.1 g Ti3C2 nanosheets and 0.025 g binder polytetrafluoroethylene were added to 50 mL ethanol and ultrasonically dispersed for 40 min to obtain Ti3C2 nanosheet nanoparticle paste; (4) Spray coating: Using a nano-slurry pneumatic sprayer, Ti3C2 nano-slurry and rare earth bromine oxide nano-slurry were sequentially sprayed layer by layer onto the surface of the porous titanium plate. The spraying pressure was 0.6 MPa, the spraying distance was 15 cm, and the film was dried at 100℃ for 30 min to obtain the anode composite film. The total thickness of the electron shuttle layer and the electro-adsorption layer in the anode composite film was 25 μm, the average pore size of the electron shuttle layer and the electro-adsorption layer was 60 nm, and the resistivity was 1.6 × 10⁻⁶. -3 Ω·m, the permeability to 10 mM KNO3 electrolyte solution is 260 h. -1 ·m -2 ·bar-1 .

[0031] Comparative Example 1: Without an electron shuttle layer, the thickness of the electrically controlled adsorption layer is 25 μm, the bromide ion concentration in the simulated high-chlorine brine is 1000 mg / L, and everything else is the same as in Example 1; After the initial adsorption reaction of 60 min, the anode composite membrane composite material had an adsorption capacity of 91.4 mg / g for bromide ions and a bromine-chlorine separation factor of 68.7; after 90 min, the adsorption capacity was 111.3 mg / g. After five consecutive cycles of adsorption and desorption (each cycle lasting 90 min), the bromide ion adsorption capacity decreased to 108.4 mg / g.

[0032] Comparative Example 2: Without an electron shuttle layer, the thickness of the electrically controlled adsorption layer is 25 μm, the bromide ion concentration in the simulated high-chlorine brine is 1000 mg / L, and other parameters are the same as in Example 2; after the first adsorption reaction of 60 min, the anode composite membrane composite material adsorbs 97.6 mg / g of bromide ions and the bromine-chlorine separation factor is 75.3; after 90 min, the adsorption capacity is 118.9 mg / g.

[0033] After five consecutive cycles of adsorption and desorption (each cycle lasting 90 min), the bromide ion adsorption capacity decreased to 114.2 mg / g.

[0034] Comparative Example 3: Step (4) was prepared by coating method, simulating a bromide ion concentration of 1000 mg / L in high-chlorine brine, and the rest was the same as in Example 1; Testing revealed poor uniformity in the thickness of the anode composite film, and the resistivity of the electron shuttle layer and the electro-controlled adsorption layer was 3.5 × 10⁻⁶. -3 Ω·m; After 60 min of the initial adsorption reaction, the anode composite membrane composite material had an adsorption capacity of 126.8 mg / g for bromide ions and a bromine-chlorine separation factor of 95.2. After three consecutive cycles of adsorption and desorption (each cycle lasting 60 min), the bromide ion adsorption capacity decreased to 73.2 mg / g.

Claims

1. A sandwich-structured anode composite membrane, characterized in that: It includes a conductive substrate layer, and an electron shuttle layer and an electro-controlled adsorption layer sequentially disposed on the conductive substrate layer; The conductive substrate layer is a porous titanium plate; The electron shuttle layer is composed of Ti3C2 nanosheets and a binder; The electro-adsorption layer is composed of rare earth bromine oxide nanosheets and a binder; the rare earth bromine oxide nanosheets are LaOBr nanosheets or CeOBr nanosheets.

2. The sandwich-structured anode composite membrane according to claim 1, characterized in that: The mass ratio of the rare earth bromide nanosheets to Ti3C2 nanosheets is 1~3:

1.

3. The sandwich-structured anode composite membrane according to claim 1, characterized in that: The porous titanium plate has a pore size of 100~500 nm, a porosity of 40~60%, and a thickness of 1.5~2 mm.

4. The sandwich-structured anode composite membrane according to claim 1, characterized in that: The binder content in both the electron shuttle layer and the electro-adsorption layer is 6-20%.

5. The sandwich-structured anode composite membrane according to claim 1, characterized in that: The thickness of the Ti3C2 nanosheets is 1~5 nm, the thickness of the rare earth bromine oxide nanosheets is ≤3 nm, and the total thickness of the electron shuttle layer and the electro-controlled adsorption layer is 10~50 μm.

6. The method for preparing the sandwich-structured anode composite film according to claim 1, characterized in that: Includes the following steps: (1) Preparation of rare earth bromine oxide nanosheets: Dissolve rare earth metal nitrates and polyvinylpyrrolidone in water, add KBr solution dropwise, stir the reaction at room temperature for 30-60 min, wash the product with water and ethanol, and freeze dry under vacuum to obtain rare earth bromine oxide nanosheets. (2) Preparation of rare earth bromine oxide nanoparticle paste: The rare earth bromine oxide nanosheets and binder are added to ethanol and ultrasonically dispersed for 40-60 min to obtain rare earth bromine oxide nanoparticle paste; (3) Preparation of Ti3C2 nanosheet nanoparticle paste: Ti3C2 nanosheets and binder were added to ethanol and ultrasonically dispersed for 40-60 min to obtain Ti3C2 nanosheet nanoparticle paste; (4) Spraying and forming: Using a nano-slurry pneumatic spraying machine, Ti3C2 nano-slurry and rare earth bromine oxide nano-slurry are sprayed onto the surface of the porous titanium plate layer by layer and then dried.

7. The method for preparing the sandwich-structured anode composite film according to claim 6, characterized in that: The operating conditions of the nano-slurry pneumatic spraying machine are as follows: spraying air pressure is 0.3~0.6 MPa, and spraying distance is 5~15 cm.

8. The method for preparing the sandwich-structured anode composite film according to claim 6, characterized in that: The mass ratio of the rare earth metal nitrate to polyvinylpyrrolidone is 10~17.5:1; the molar ratio of the rare earth metal nitrate to KBr in the KBr solution is 0.8~1.2:

1.

9. A method for extracting bromine from bromine-containing high-chlorine brine based on electro-controlled ion exchange, characterized in that: Includes the following steps: (a) Separation of bromine: Using the sandwich structure anode composite membrane described in claim 1 as the anode and the titanium mesh as the cathode, bromine-containing high-chlorine brine is passed into the electrolytic cell, and hydrochloric acid solution is passed into the cathode cell at the same flow rate. A voltage of 0.8~1.4 V is applied, and adsorption by electro-controlled ion exchange is carried out at room temperature and pressure to achieve selective adsorption and separation of bromine ions. (II) Enrichment of bromine: After adsorbing bromide ions, the brine in the electrolytic cell is discharged and pure water is introduced for analysis. The anode and cathode in step (I) are interchanged, and a voltage of 1.4~2 V is applied. Desorption by electro-controlled ion exchange is carried out at room temperature and pressure to achieve the enrichment of bromide ions.

10. The method for extracting bromine from bromine-containing high-chlorine brine based on electro-controlled ion exchange according to claim 9, characterized in that: The pH value of the hydrochloric acid solution is 1.5~2; the adsorption time in step (I) is 60~90 min; the desorption time in step (II) is 60~90 min.

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