Electrode material for extracting bromine in brine by using electronic control ion exchange technology as well as preparation method and application of electrode material

Abstract

The invention provides an electro-adsorption material for electrochemically extracting bromine as well as a preparation method and application of the electro-adsorption material. The electro-adsorption material comprises a bromide ion trap membrane electrode prepared from bismuth oxybromide nanosheets, carbon black and PVDF, and a bromide ion trap membrane which is loaded on the surface of the bismuth oxybromide membrane electrode and is formed by aniline, potassium bromide and hydrobromic acid. The mass ratio of the bismuth oxybromide nanosheet to the carbon black to the PVDF to the aniline to the potassium bromide to the hydrobromic acid is (1-50): (0.1-5): (0.1-5): (0.1-25): (1-250): (0.2-50). 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 oilfield brine.

Description

Technical Field

[0001] The invention belongs to the technical field of bromine extraction, and in particular relates to an electric adsorption material for electrochemical extraction of bromine, a preparation method and application thereof. Background Art

[0002] Bromine is one of the important chemical raw materials, mainly used in fine chemicals, high-end manufacturing, environmental protection, petrochemicals, medicine, energy storage and other fields. There are more than 100 related high value-added products, which are necessary resources for a complete industrial system. The demand for bromine and bromine-based chemicals has been increasing year by year, and they are in short supply in my country. Bromine resources mainly include groundwater in oil and gas fields, brine in salt lakes, bitter brine in sea salt fields and brine in salt mines. Among them, underground brine in oil and gas fields and brine in salt lakes are brine bromine resources with the highest bromine concentration and the best quality. Therefore, the extraction of bromine from brine has received more and more attention. my country's bromine resources are of low grade and small total amount, mainly from underground brine in Shandong Province. Due to continuous exploitation year by year, the bromine content of underground brine has dropped rapidly, which has increased the cost of bromine extraction and the difficulty of bromine extraction. Therefore, the development of bromine extraction technology suitable for low-grade resources has received increasing attention. In addition, due to problems such as process technology, the utilization rate of underground brine is low, resulting in a large waste of resources. Bromine resources are facing a crisis, and more bromine-containing resources need to be developed and utilized. However, there are many challenges in extracting bromine from brine, such as the low content of bromine in brine and the chlorine in brine will interfere with the extraction of bromine. In order to selectively extract bromine from brine, a variety of bromine extraction technologies have emerged, such as adsorption, solvent extraction, precipitation, etc. Taking environmental factors into consideration, ion exchange, membrane separation and electrochemical ion exchange (Electrically Switched Ion Exchange, ESIX) have been proposed. Compared with ESIX technology, other technologies have the disadvantages of long production cycle, high cost, environmental pollution and complex process. Therefore, the more efficient, energy-saving and environmentally friendly ESIX technology has attracted much attention. This technology selectively achieves the target ions (such as Li) by adjusting the redox state of the electroactive ion exchange materials (EXIMs) coated on the thin film electrodes. + Br - , Cl - ,I - , Cs +With the continuous improvement and optimization of electroactive ion exchange materials, the adsorption amount of target ions and the cyclic stability of the materials themselves have been significantly improved. The application conditions of ESIX technology are mild, and electricity is used as the driving force. In addition to the chemical or physical adsorption of the membrane material itself, the application of potential will increase its adsorption and desorption of anions and cations, which can be used to separate ions with lower concentrations in the solution; no chemical regeneration is required during the separation process, avoiding secondary pollution caused by chemical regeneration agents. The key to applying this technology to the separation of bromine in oilfield brine is to study a functional membrane material that is both electroactive and selective for adsorption of bromide ions. Electroactive materials can conduct both electrons and ions, and the target ions can be placed in and out by changing the redox state of the electroactive materials. However, the adsorption capacity of the electrode active materials currently used for the extraction of bromine in oilfield brine is low, and the cyclic performance is poor, which cannot effectively meet the actual application needs of bromine extraction in oilfield brine. Summary of the invention

[0003] In order to solve all or part of the above technical problems, the present invention provides the following technical solutions: One of the purposes of the present invention is to provide an electrosorption material for electrochemical extraction of bromine, the electrosorption material comprising a Br-BiOBr membrane electrode prepared from bismuth oxybromide nanosheets, carbon black and PVDF, and a bromide ion trap membrane constructed from aniline, potassium bromide and hydrobromic acid supported on the surface of the bismuth oxybromide membrane electrode. The mass ratio of the bismuth oxybromide nanosheets, carbon black, PVDF to the aniline, potassium bromide and hydrobromic acid is 1-50: 0.1-5: 0.1-5: 0.1-25: 1-250: 0.2-50.

[0004] The aniline in the electro-adsorption material forms polyaniline with a molecular chain having a conjugated structure. There are freely movable π electrons on the molecular chain. When an electric field is applied, the π electrons move in a directional manner to form a current. The bromine source is introduced when the molecular chain is formed, and then the bromide ions are removed by applying a potential. Holes are formed on the molecular chain, and the holes have recognition for bromide ions. Depositing it on bismuth oxybromide nanosheets can improve the conductivity and adsorption performance of the composite material. The electro-adsorption material has a large adsorption capacity, a fast adsorption rate and excellent selective adsorption for bromine elements, and is not interfered by other anions in the sample during adsorption; and the composite material also exhibits good cycle stability and low dissolution loss.

[0005] In some embodiments, according to the BET test, the specific surface area of ​​the electro-adsorption material is 5 to 10 times that of a simple bismuth oxybromide nanosheet. The surface of a simple bismuth oxybromide nanosheet is relatively smooth. When a simple bismuth oxybromide nanosheet is directly used as a bromine adsorption material, the conductivity is poor and the adsorption efficiency is low. The present invention finds that the surface roughness of the bismuth oxybromide nanosheet deposited with the bromide ion trap polyaniline film increases, and the rough surface increases the specific surface area of ​​the material, making its specific surface area more than 5 to 10 times that of a single bismuth oxybromide nanosheet without compounding, providing more abundant active sites for the capture and release of bromine.

[0006] In some embodiments, the bismuth oxybromide nanosheet has a diameter of 50-1000 nm and a thickness of 50-500 nm, and the bromide ion trap polyaniline film is deposited on the surface of the bismuth oxybromide nanosheet, and the coating thickness is 10-1000 nm.

[0007] According to the thermogravimetric analysis test (TG test), the initial weight loss temperature of the electrosorption material is 560°C, which indicates that it has good high temperature resistance and can adapt to most brine temperature environments.

[0008] The second object of the present invention is to provide a method for preparing the electrosorption material, comprising: Bismuth oxybromide nanosheets were synthesized by room temperature hydrolysis method; A membrane electrode containing the bismuth oxybromide nanosheets, carbon black and PVDF is prepared by a mechanical coating method, an oxidizing potential is applied to the bismuth oxybromide membrane electrode, and a bromide ion trap bismuth oxybromide (Br-BiOBr) membrane electrode is preliminarily prepared. The Br-BiOBr membrane electrode is then placed in a mixed solution of hydrobromic acid, aniline, and potassium bromide / sodium bromide, a positive potential is applied for electrodeposition, and after the electrodeposition is completed, it is taken out and replaced in a sodium chloride solution, a negative potential is applied, and bromide ions on the surface are removed to form holes on the membrane electrode surface. After washing the membrane electrode surface with deionized water, a bromide ion trap bismuth oxybromide-based polyaniline composite membrane electrode (Br-BiOBr@PANI) is obtained.

[0009] In some embodiments, in the bromide ion trap conductive substrate, the mass ratio of bismuth oxybromide nanosheets, carbon black and PVDF is 1-50:0.1-5:0.1-5.

[0010] In some embodiments, the mass ratio of aniline, potassium bromide and hydrobromic acid in the electrodeposited bromide ion trap film is 0.1-25:1-250:0.2-50.

[0011] In some embodiments, when the bismuth oxybromide bromide ion trap membrane electrode is prepared, the applied potential is -0.8~-1.2V.

[0012] In some embodiments, the potential applied for the electrodeposition is 0.8-1.2V.

[0013] In some embodiments, the sodium chloride solution required for desorption has a concentration of 100 mg to 300 mg / L and a desorption potential of -0.8 to -1.2 V.

[0014] In some embodiments, the room temperature hydrolysis method comprises: reacting a reaction system containing a bismuth source and a bromine source at room temperature, wherein the pH value of the reaction system is 5-8, to obtain bismuth oxybromide nanosheets.

[0015] In some embodiments, the concentration of the bismuth source in the reaction system is 0.1-1 mol / L, and the concentration of the bromine source is 0.1-1 mol / L.

[0016] In some embodiments, the bismuth source includes Bi(NO3)3∙5H2O, and the bromine source includes KBr.

[0017] In some embodiments, the concentrations of aniline, potassium bromide and hydrobromic acid in the mixed solution are 0.05-0.5 mol / L.

[0018] In some embodiments, the electrodeposition time is 30 to 120 minutes.

[0019] A third object of the present invention is to provide a bromine active electrode, wherein the bromine active electrode comprises the electrosorption material.

[0020] In some embodiments, the bromine active electrode comprises a bromide ion trap conductive substrate and a bromide ion trap film layer electrodeposited on the conductive substrate, and the composite film layer comprises an electro-adsorption material, a conductive material and a binder.

[0021] In some embodiments, in the bromide ion trap conductive substrate, the mass ratio of the electrosorption material, the conductive material and the binder is 1~50:0.1~5:0.1~5. For example, the electrosorption material, the conductive material and the binder are uniformly mixed according to the above mass ratio and an appropriate amount of solvent is added to form a slurry, and the slurry is coated on the conductive substrate and solidified to form the composite membrane electrode. The membrane electrode is placed in an electrolytic cell and an oxidation potential is applied to form a Br-BiOBr membrane electrode. With the membrane electrode as the matrix, the mixed solution of aniline, hydrobromic acid and potassium bromide is attached to the bromide ion trap bismuth oxide membrane matrix by electrodeposition, and then placed in an electrolytic cell and an oxidation potential is applied to remove bromide ions. The Br-BiOBr@PANI membrane electrode is prepared. The slurry made of the electrosorption material has good ductility, and a small amount of preparation can be used on a large area for a long time; the electrosorption material has low cost and good economic efficiency, and thus has industrial and commercial prospects.

[0022] In some embodiments, the conductive material includes one or a combination of carbon black, graphene, and acetylene black, but is not limited thereto.

[0023] In some embodiments, the binder includes one or a combination of polyvinylidene fluoride, polyacrylic acid, polymethacrylic acid, and polyvinyl alcohol, but is not limited thereto.

[0024] 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 is carbon paper, a carbon sheet, a titanium sheet, or nickel foam.

[0025] In some embodiments, in the electrodeposited bromide ion trap film, the bromine source may be a combination of one or more of potassium bromide, sodium bromide, lithium bromide, and magnesium bromide.

[0026] A fourth object of the present 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 bromine active electrode.

[0027] A fifth object of the present invention is to provide the use of the electro-adsorption material, the bromine-active electrode or the bromine extraction system in extracting bromine from brine.

[0028] In some embodiments, the brine is oilfield brine. The present invention finds that the electro-adsorption material of the bromide ion trap polyaniline membrane electrodeposited with bismuth oxybromide nanosheets has strong stability, and the extraction of bromide ions is controlled by the applied redox potential and is not easily interfered by other impurities in the sample, and is particularly suitable for the extraction of bromide ions in oilfield brine or other more extreme environments.

[0029] A sixth object of the present invention is to provide a method for extracting bromine from oilfield brine, wherein the system for extracting bromine comprises: Applying a voltage of -0.8 to -1.2 V to the bismuth oxybromide film electrode to remove bromide ions between bismuth oxybromide nanosheet layers to prepare the Br-BiOBr bromine active electrode; The bromide ion trap bismuth oxybromide membrane electrode is used as a substrate and placed in a mixed solution of aniline, hydrobromic acid and potassium bromide, and a voltage of 0.8~1.2V is applied for 30~120min for electrodeposition. After electrodeposition, it is placed in a 100~300mg / L potassium bromide solution and a voltage of -0.8~-1.2V is applied to remove bromide ions on the surface of the membrane electrode to obtain a Br-BiOBr@PANI bromine active electrode.

[0030] The Br-BiOBr@PANI bromine active electrode is placed in oilfield brine, and a voltage of 0.8-1.2 V is applied to allow the bromine active electrode to adsorb bromide ions in the oilfield brine to achieve bromine extraction.

[0031] The method for extracting bromine from oilfield brine does not require acid or alkali elution of bromide ions, and the adsorption and desorption of bromine can be achieved after applying voltage. The overall process of the entire electrical adsorption process is simple, efficient, low-cost, and environmentally friendly.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects: the electrosorption material for extracting bromine prepared by the present invention has a large adsorption capacity, good cycle stability and excellent selective adsorption; the electrosorption material still has a certain adsorption capacity for solutions with a bromide ion content of less than 100 mg / L. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an electron microscope image of the Br-BiOBr@PANI composite material prepared in one embodiment of the present invention; Figure 2 , 3 Schematic diagram of the three-electrode system constructed in one embodiment of the present invention for extracting bromide ions. Figure 4 It is a comparison diagram of the adsorption performance of the bromine active electrode prepared in one embodiment of the present invention under voltage conditions of 0.8V, 0.9V, 1.0V, 1.1V, and 1.2V respectively; Figure 5 The adsorption amount of bromine active electrode prepared by one embodiment of the present invention changes with time; Figure 6 It is the change of the adsorption amount of the bromine active electrode prepared in one embodiment of the present invention after 10 cycles.

Claims

1. An electrosorption material for electrochemical extraction of bromine, characterized in that: include: A bromide ion trap membrane electrode prepared from bismuth oxybromide nanosheets, carbon black and PVDF, and a bromide ion trap membrane constructed from aniline, potassium bromide and hydrobromic acid supported on the surface of the bismuth oxybromide membrane electrode. The mass ratio of the bismuth oxybromide nanosheets, carbon black, PVDF to the aniline, potassium bromide and hydrobromic acid is 1-50: 0.1-5: 0.1-5: 0.1-25: 1-250: 0.2-50.

2. The electrosorption material according to claim 1, characterized in that: According to the BET test, the specific surface area of ​​the electrosorption material is 5 to 20 times that of the bismuth oxybromide nanosheets; And / or, the bismuth oxybromide nanosheet has a sheet diameter of 50-1000 nm and a thickness of 50-500 nm, and the bromide ion trap film constructed by aniline, potassium bromide and hydrobromic acid has a coating thickness of 10-1000 nm on the surface of the bismuth oxybromide nanosheet; And / or, according to thermogravimetric analysis, the electrosorption material begins to lose weight significantly at a temperature of 560°C.

3. The method for preparing the electrosorption material according to claim 1 or 2, characterized in that: include: Bismuth oxybromide nanosheets were synthesized by room temperature hydrolysis method; A membrane electrode containing the bismuth oxybromide nanosheets, carbon black and PVDF is prepared by a mechanical coating method, an oxidizing potential is applied to the bismuth oxybromide membrane electrode, and a bromide ion trap bismuth oxybromide (Br-BiOBr) membrane electrode is preliminarily prepared. The Br-BiOBr membrane electrode is then placed in a mixed solution of hydrobromic acid, aniline, and potassium bromide / sodium bromide, a positive potential is applied for electrodeposition, and after the electrodeposition is completed, it is taken out and replaced in a sodium chloride solution, a negative potential is applied, and bromide ions on the surface are removed to form holes on the membrane electrode surface. After washing the membrane electrode surface with deionized water, a bromide ion trap bismuth oxybromide-based polyaniline composite membrane electrode (Br-BiOBr@PANI) is obtained.

4. The preparation method according to claim 3, characterized in that: In the bismuth oxybromide membrane electrode, the mass of bismuth oxybromide nanosheets, carbon black and PVDF is 1-50:0.1-5:0.1-5 g; And / or, when the bismuth oxybromide bromide ion trap membrane electrode is prepared, the applied potential is -0.8~-1.2V; And / or, the concentrations of aniline, potassium bromide and hydrobromic acid in the mixed solution are 0.05-0.5 mol / L; And / or, the potential applied for the electrodeposition is 0.8-1.2 V, and the electrodeposition time is 30-120 min; And / or, the sodium chloride solution required for the desorption has a concentration of 100 mg to 300 mg / L and a desorption potential of -0.8 to -1.2 V.

5. A bromine-active electrode, characterized in that: Comprising the electrosorption material according to claim 1 or 2.

6. The bromine active electrode according to claim 5, characterized in that: The bromine active electrode comprises a Br-BiOBr conductive substrate and a bromide ion trap membrane layer electrodeposited on the conductive substrate, and the composite membrane layer comprises the electric adsorption material according to claim 1 or 2, a conductive material and a binder.

7. The bromine-active electrode according to claim 6, characterized in that: In the bromide ion trap conductive substrate, the mass ratio of the electric adsorption material, the conductive material and the binder is 1-50:0.1-5:0.1-5; And / or, the mass ratio of aniline, bromine source and hydrobromic acid in the electrodeposited bromide ion trap film is 0.1-25:1-250:0.2-50 And / or, the conductive material includes one or a combination of carbon black, graphene, and acetylene black; 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 with the conductive film preparation material includes one or a combination of carbon, titanium and nickel; And / or, in the electro-deposited bromide ion trap film, the bromine source may be a combination of one or more of potassium bromide, sodium bromide, lithium bromide and magnesium bromide.

8. A system for extracting bromine, characterized in that: include: A working electrode, a counter electrode and a reference electrode, wherein the working electrode is the bromine active electrode as described in any one of claims 5 to 7.

9. Use of the electric adsorption material according to claim 1 or 2, the bromine active electrode according to any one of claims 5 to 7, or the bromine extraction system according to claim 8 in extracting bromine from brine; Preferably, the brine is oilfield brine.

10. A method for extracting bromine from oilfield brine, characterized in that: The system for extracting bromine according to claim 8 comprises: The bromine active electrode is placed in oilfield brine, and a voltage of 0.6-1.2V is applied to enable the bromine active electrode to adsorb bromide ions in the oilfield brine to achieve bromine extraction.

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