Method for preparing metal-organic framework-based stainless steel porous membrane from heavy metal in electroplating wastewater and application

Abstract

The application discloses a method for preparing a metal-organic framework-based stainless steel porous membrane from heavy metals in electroplating wastewater and application thereof. By loading conductive polymers and conductive polymer composites on the surface of a stainless steel mesh, the conductivity and electrochemical activity of the electrode are significantly increased, which helps to promote the reduction reaction of heavy metals in the electrodeposition process. The conductive polymer-based stainless steel can break the coordination structure of the complex, destroy the complex balance state of metal ions and other substances, and make the metal ions deposit on the stainless steel. The metal-organic framework catalytic membrane is in-situ constructed on the surface of the metal-organic framework-based stainless steel porous electrode material by electrodeposition, and the catalytic membrane can be used for degrading tetracycline, norfloxacin and sulfamethoxazole antibiotics, so as to finally achieve the goal of waste treatment by waste. The innovation provides a more sustainable solution for electroplating wastewater treatment and valuable metal resource recycling.

Description

Technical Field

[0001] This application relates to the fields of electrocatalysis and water treatment technology, and in particular to a method and application for preparing metal-organic framework-based stainless steel porous membranes by recovering heavy metals from electroplating wastewater. Background Technology

[0002] Electroplating wastewater contains heavy metal ions (such as chromium, nickel, and copper) and various complexed metals. If discharged directly into the environment without treatment, it can pollute soil and water bodies, harming the balance of ecosystems and biodiversity. Electroplating wastewater has significant recycling value. The heavy metal ions and complexed metals it contains can be recovered and reused through electrodeposition. MOF (Metal-Oxide-Film) films can be grown in situ on the electrodeposited material using conductive polymer-modified stainless steel porous electrodes. The advantages of conductive polymer-modified stainless steel porous electrodes include the following:

[0003] 1. Electrical conductivity: Polypyrrole has good electrical conductivity, which helps to form efficient electrical conduction channels.

[0004] 2. Active sites: The surface of graphene oxide contains abundant functional groups, which provide active sites for the adsorption and reduction of metal ions.

[0005] 3. Surface area: The large surface area of ​​the conductive polymer-modified stainless steel porous electrode provides more reaction sites and enhances the efficiency of electrodeposition.

[0006] In summary, conductive polymer-modified stainless steel porous electrodes can serve as excellent electrode materials, and are expected to solve the problem of high-performance antibiotic removal by growing MOF films in situ on the electrode surface after removing heavy metal ions from electroplating wastewater. Summary of the Invention

[0007] Technical problems to be solved:

[0008] The technical problem this application aims to solve is that electroplating wastewater contains heavy metal ions and various complexed metals. If discharged directly into the environment without treatment, it can lead to soil and water pollution, harming the balance of ecosystems and biodiversity. Furthermore, it addresses issues such as the difficulty in breaking down complexed heavy metals and the challenges in achieving uniformity and high performance of MOF (Metal-Organic Framework) membranes. Based on the shortcomings of existing technologies, this application provides a method and application for recovering heavy metals from electroplating wastewater to prepare metal-organic framework-based porous stainless steel membranes. Polypyrrole and graphene oxide are electrochemically deposited onto the stainless steel surface, solving the problems of difficult removal of heavy metal ions and deposition of complexed metals from electroplating wastewater. After electrodeposition, MOF membranes can be grown in situ on the electrode material surface by changing the solution, and these membranes can be used to address the degradation problems of various antibiotics.

[0009] Technical solution:

[0010] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater specifically includes the following steps:

[0011] Step 1: Synthesize conductive polymers or conductive polymer composites on stainless steel mesh to obtain stainless steel mesh electrode materials modified with conductive polymers or conductive polymer composites;

[0012] Step 2: Electroplating wastewater is treated by electrodeposition of the obtained conductive polymer or conductive polymer composite modified stainless steel mesh electrode material to obtain electrode material with deposited heavy metals.

[0013] Step 3: The electrode material with heavy metal deposits is converted into MOFs membrane in situ by electrosynthesis to obtain metal-organic framework-based stainless steel porous membrane.

[0014] As a preferred technical solution of this application: the conductive polymer in the first step is polypyrrole and / or polyaniline, and the conductive polymer composite material is polypyrrole / graphene oxide or polyaniline / 8-hydroxyquinoline.

[0015] As a preferred technical solution of this application: the stainless steel mesh electrode material modified by conductive polymer composite material is a stainless steel mesh electrode material modified by polypyrrole / graphene oxide composite material. The synthesis method is to synthesize polypyrrole on a stainless steel mesh, and then deposit a layer of graphene oxide on the polypyrrole-modified stainless steel mesh to obtain the stainless steel mesh electrode material modified by polypyrrole / graphene oxide composite material, so as to enhance the conductivity and electrochemical activity of stainless steel.

[0016] As a preferred technical solution of this application: the electroplating wastewater in the second step contains one or more of Cu, Pb, Ni and Co, and the heavy metals in the electrode material with deposited heavy metals are heavy metal elements or metal oxides.

[0017] As a preferred technical solution of this application, the first step specifically involves the following steps:

[0018] Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface;

[0019] Step 2: Prepare 200 ml of 0.4 M conductive polymer monomer or a mixture of conductive polymer monomer and other substances, and 0.15 M sodium dodecyl sulfate (SDS) electrolyte solution.

[0020] Step 3: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, a conductive polymer or conductive polymer composite material is electrosynthesized on the stainless steel mesh under constant voltage. After synthesis, the material is removed and dried in a drying oven at 60°C for 2 hours. The electrosynthesis conditions are either constant voltage 1.5V for 12 hours or constant voltage 3V for 30 minutes.

[0021] As a preferred technical solution of this application: the 0.4M conductive polymer monomer is a 0.4M pyrrole monomer or a 0.4M aniline monomer, and the other substances are graphene oxide and / or 8-hydroxyquinoline, and the conductive polymer monomer and other substances in the mixed solution are all 0.4M.

[0022] As a preferred technical solution of this application: The second step is as follows: In a continuous flow device, 1L of simulated electroplating wastewater or real electroplating wastewater solution is added, and a stainless steel mesh electrode material modified with conductive polymer or conductive polymer composite material is used as the cathode and a titanium sheet is used as the anode. Electrodeposition is performed at a constant voltage of 10V for 2 hours to obtain an electrode material with deposited heavy metals. 10ml of solution is taken before and after electrodeposition and the metal ion concentration is measured by ICP.

[0023] As a preferred technical solution of this application: the third step is as follows: 8 mmol / L of 1,3,5-benzenetricarboxylic acid and 20 mmol / L of NaCl are added to 2L of pure water, and the mixture is sonicated for 30 minutes to prepare 2L of 0.04M organic ligand solution. The electrode material with heavy metal deposition obtained in the second step is used as the anode, and a titanium sheet is used as the cathode. The MOFs catalytic membrane is synthesized by electrolysis at a constant voltage of 1.5V for 12 hours to obtain a metal-organic framework-based stainless steel porous membrane. The organic ligand is 1,3,5-benzenetricarboxylic acid or terephthalic acid.

[0024] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater is disclosed. The resulting metal-organic framework-based stainless steel porous membrane is used in in-situ for the degradation of pollutants. The method employs electrocatalysis, with the metal-organic framework-based stainless steel porous membrane as the anode and a titanium sheet as the cathode, to degrade pollutants in situ under a constant current electric field of 0.08A.

[0025] As a preferred technical solution of this application: the pollutants are tetracycline, norfloxacin, and sulfamethoxazole, and the applied electric field is a constant current of 0.08A.

[0026] The technical principle of this application is as follows: The metal-organic framework-based stainless steel of this invention has good electrical conductivity, which can deposit metal ions and break the coordination structure of complexed substances, thereby disrupting the equilibrium state of the complexed metals; in addition, the metal electrodeposited on the surface of the stainless steel can provide a metal source for the subsequent in-situ conversion of MOFs films; the metal centers of MOFs can participate in the electron transfer process and undergo direct redox reactions with antibiotic molecules; this electron transfer process can change the electronic structure of antibiotic molecules, leading to their degradation, and achieving the ultimate goal of treating waste with waste.

[0027] Beneficial effects:

[0028] The method and application of the method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater described in this application have the following technical advantages compared with the prior art:

[0029] 1. The stainless steel loaded with conductive polymer of the present invention can exist stably in the electrolyte solution and can remain stable throughout the entire electrodeposition and MOF conversion process.

[0030] 2. The electrode material in this invention has a relatively large saturation adsorption capacity for heavy metal ions during the electrodeposition process, which is due to the ultra-high specific surface area brought about by the composite material.

[0031] 3. This invention can break the complexed metal in electroplating wastewater, disrupt the complexation balance between metal ions and other substances, and cause it to deposit on stainless steel; and convert it in situ into MOFs membranes, which can be used to degrade antibiotics such as tetracycline TC, norfloxacin NOR, and sulfamethoxazole SMX, achieving the effect of treating waste with waste.

[0032] 4. After the electrode material of the present invention has undergone metal electrodeposition, an MOF film can be grown in situ, which has a good removal effect on antibiotics such as tetracycline. Attached Figure Description

[0033] Figure 1 (a) and (b) are electron micrographs of the surface of stainless steel; (c) and (d) are electron micrographs of the surface of polypyrrole / stainless steel.

[0034] Figure 2 The diagram shows the removal effect of the polypyrrole / stainless steel electrode material of this application on various metal ions;

[0035] Figure 3 The image shows the removal effect of the polypyrrole / stainless steel electrode material of this application on complexed metal ions;

[0036] Figure 4 (a) and (b) are surface morphology images of the electrode material loaded with Cu-MOF (HKUST-1); (c)-(f) are shape images of HKUST-1.

[0037] Figure 5 (a) is the XRD pattern of HKUST-1 grown on the surface of the electrode material; (b) is the XRD pattern of Pb-BTC grown on the surface of the electrode material; (c) is the XRD pattern of Zn-BTC grown on the surface of the electrode material.

[0038] Figure 6 The image shows the removal effect of HKUST-1 / stainless steel on tetracycline, norfloxacin, and sulfamethoxazole. Detailed Implementation

[0039] The present invention will now be explained in more detail with reference to specific embodiments. It is worth noting that the embodiments listed are not all embodiments, but only a part of them. Parts not explained in detail in the specific embodiments described in the invention document are the consensus of those skilled in the art.

[0040] Example 1:

[0041] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater specifically includes the following steps:

[0042] Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface; add 0.4M pyrrole monomer and 0.15M sodium dodecyl sulfate (SDS) to 200ml of pure water, and then dissolve them by ultrasonic cleaning in an ultrasonic cleaner for 2 hours.

[0043] Step 2: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, polypyrrole is electrosynthesized on the stainless steel mesh with a constant voltage of 1.5V. After 12 hours of synthesis, the material is removed and dried in a drying oven at 60℃ for 2 hours. After drying, the modified stainless steel material is removed.

[0044] Step 3: Dissolve CuCl2 (80 mg / L) and NaCl (0.02 mol / L) together in 200 ml of pure water, and sonicate for 10 minutes to obtain an electroplating wastewater solution;

[0045] Step 4: In a continuous flow apparatus, add electroplating wastewater solution, use modified stainless steel as cathode and titanium sheet as anode, and perform electrodeposition at a constant voltage of 10V for 2 hours. After reaching saturation, an electrode material with deposited heavy metals is obtained as the anode. Take 10ml of solution before and after electrodeposition and measure the metal ion concentration by ICP.

[0046] Step 5: Add 1,3,5-benzenetricarboxylic acid (8 mmol / L) and NaCl (20 mmol / L) to 2L of pure water, sonicate for 30 minutes to dissolve, and prepare 2L of 0.04M organic ligand solution;

[0047] Step 6: In a continuous flow apparatus, an organic ligand solution is added, and an electrode material with deposited heavy metals is used as the anode and a titanium sheet as the cathode. The MOF catalytic membrane is synthesized by constant voltage 1.5V for 12 hours to obtain a metal-organic framework-based stainless steel porous membrane.

[0048] Step 7: Prepare 1L of 5mg / L tetracycline solution, add 2.84g of NaSO4, and use electrocatalysis with a metal-organic framework-based stainless steel porous membrane as the anode and a titanium sheet as the cathode to degrade the pollutant in situ under an applied electric field. No current is applied for the first half hour for 30 minutes to eliminate adsorption, and then a constant current of 0.08A is applied for degradation for 120 minutes.

[0049] Example 2

[0050] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater specifically includes the following steps:

[0051] Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface; add 0.4M pyrrole monomer and 0.15M sodium dodecyl sulfate (SDS) to 200ml of pure water, and then ultrasonically dissolve them in an ultrasonic cleaner for 2 hours.

[0052] Step 2: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, polypyrrole is electrosynthesized on the stainless steel mesh with a constant voltage of 1.5V. After 12 hours of synthesis, the material is removed and dried in a drying oven at 60℃ for 2 hours. After drying, the modified stainless steel material is removed.

[0053] Step 3: Dissolve PbCl2 (80 mg / L) and NaCl (0.02 mol / L) together in 200 ml of pure water, and sonicate for 10 minutes to obtain an electroplating wastewater solution;

[0054] Step 4: In a continuous flow apparatus, add electroplating wastewater solution, use modified stainless steel as cathode and titanium sheet as anode, and perform electrodeposition at a constant voltage of 10V for 2 hours. After reaching saturation, an electrode material with deposited heavy metals is obtained as the anode. Take 10ml of solution before and after electrodeposition and measure the metal ion concentration by ICP.

[0055] Step 5: Add 1,3,5-benzenetricarboxylic acid (8 mmol / L) and NaCl (20 mmol / L) to 2L of pure water, sonicate for 30 minutes to dissolve, and prepare 2L of 0.04M organic ligand solution;

[0056] Step 6: In a continuous flow apparatus, an electrode material deposited with heavy metals is used as the anode, and a titanium sheet is used as the cathode. MOFs catalytic membranes are synthesized by constant voltage 1.5V for 12 hours to obtain metal-organic framework-based stainless steel porous membranes.

[0057] Step 7: Prepare 1L of 5mg / L tetracycline solution, add 2.84g of NaSO4, and use electrocatalysis with a metal-organic framework-based stainless steel porous membrane as the anode and a titanium sheet as the cathode to degrade the pollutant in situ under an applied electric field. No current is applied for the first half hour for 30 minutes to eliminate adsorption, and then a constant current of 0.08A is applied for degradation for 120 minutes.

[0058] Example 3

[0059] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater specifically includes the following steps:

[0060] Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface; add 0.4M pyrrole monomer and 0.15M sodium dodecyl sulfate (SDS) to 200ml of pure water, and then ultrasonically dissolve them in an ultrasonic cleaner for 2 hours.

[0061] Step 2: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, polypyrrole is electrosynthesized on the stainless steel mesh with a constant voltage of 1.5V. After 12 hours of synthesis, the material is removed and dried in a drying oven at 60℃ for 2 hours. After drying, the modified stainless steel material is removed.

[0062] Step 3: Dissolve NiCl2 (80mg / L) and NaCl (0.02mol / L) together in 200ml of pure water, and sonicate for 10 minutes to obtain an electroplating wastewater solution;

[0063] Step 4: In a continuous flow apparatus, add electroplating wastewater solution, use modified stainless steel as cathode and titanium sheet as anode, and perform electrodeposition at a constant voltage of 10V for 2 hours. After reaching saturation, an electrode material with deposited heavy metals is obtained as the anode. Take 10ml of solution before and after electrodeposition and measure the metal ion concentration by ICP.

[0064] Step 5: Add 1,3,5-benzenetricarboxylic acid (8 mmol / L) and NaCl (20 mmol / L) to 2L of pure water, sonicate for 30 minutes to dissolve, and prepare 2L of 0.04M organic ligand solution;

[0065] Step 6: In a continuous flow apparatus, an electrode material deposited with heavy metals is used as the anode, and a titanium sheet is used as the cathode. MOFs catalytic membranes are synthesized by constant voltage 1.5V for 12 hours to obtain metal-organic framework-based stainless steel porous membranes.

[0066] Step 7: Prepare 1L of 5mg / L tetracycline solution, add 2.84g of NaSO4, and use electrocatalysis with a metal-organic framework-based stainless steel porous membrane as the anode and a titanium sheet as the cathode to degrade the pollutant in situ under an applied electric field. No current is applied for the first half hour for 30 minutes to eliminate adsorption, and then a constant current of 0.08A is applied for degradation for 120 minutes.

[0067] Example 4

[0068] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater specifically includes the following steps:

[0069] Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface; add 0.4M pyrrole monomer and 0.15M sodium dodecyl sulfate (SDS) to 200ml of pure water, and then ultrasonically dissolve them in an ultrasonic cleaner for 2 hours.

[0070] Step 2: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, polypyrrole is electrosynthesized on the stainless steel mesh with a constant voltage of 1.5V. After 12 hours of synthesis, the material is removed and dried in a drying oven at 60℃ for 2 hours. After drying, the modified stainless steel material is removed.

[0071] Step 3: Dissolve CoCl2 (80mg / L) and NaCl (0.02mol / L) together in 200ml of pure water, and sonicate for 10 minutes to obtain an electroplating wastewater solution;

[0072] Step 4: In a continuous flow apparatus, add electroplating wastewater solution, use modified stainless steel as cathode and titanium sheet as anode, and perform electrodeposition at a constant voltage of 10V for 2 hours. After reaching saturation, an electrode material with deposited heavy metals is obtained as the anode. Take 10ml of solution before and after electrodeposition and measure the metal ion concentration by ICP.

[0073] Step 5: Add 1,3,5-benzenetricarboxylic acid (8 mmol / L) and NaCl (20 mmol / L) to 2L of pure water, sonicate for 30 minutes to dissolve, and prepare 2L of 0.04M organic ligand solution;

[0074] Step 6: In a continuous flow apparatus, an electrode material deposited with heavy metals is used as the anode, and a titanium sheet is used as the cathode. MOFs catalytic membranes are synthesized by constant voltage 1.5V for 12 hours to obtain metal-organic framework-based stainless steel porous membranes.

[0075] Step 7: Prepare 1L of 5mg / L tetracycline solution, add 2.84g of NaSO4, and use electrocatalysis with a metal-organic framework-based stainless steel porous membrane as the anode and a titanium sheet as the cathode to degrade the pollutant in situ under an applied electric field. No current is applied for the first half hour for 30 minutes to eliminate adsorption, and then a constant current of 0.08A is applied for degradation for 120 minutes.

[0076] Example 5

[0077] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater specifically includes the following steps:

[0078] Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface; add 0.4M aniline monomer and 0.15M sodium dodecyl sulfate (SDS) to 200ml of pure water, and then ultrasonically dissolve them in an ultrasonic cleaner for 2 hours.

[0079] Step 2: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, polyaniline is electrosynthesized on the stainless steel mesh using a constant voltage of 3.5V. After 0.5 hours of synthesis, the material is removed and dried in a drying oven at 60℃ for 2 hours. After drying, the modified stainless steel material is removed.

[0080] Step 3: Dissolve CuCl2 (80 mg / L) and NaCl (0.02 mol / L) together in 200 ml of pure water, and sonicate for 10 minutes to obtain an electroplating wastewater solution;

[0081] Step 4: In a continuous flow apparatus, add electroplating wastewater solution, use modified stainless steel as cathode and titanium sheet as anode, and perform electrodeposition at a constant voltage of 10V for 2 hours. After reaching saturation, an electrode material with deposited heavy metals is obtained as the anode. Take 10ml of solution before and after electrodeposition and measure the metal ion concentration by ICP.

[0082] Step 5: Add 1,3,5-benzenetricarboxylic acid (8 mmol / L) and NaCl (20 mmol / L) to 2L of pure water, sonicate for 30 minutes to dissolve, and prepare 2L of 0.04M organic ligand solution;

[0083] Step 6: In a continuous flow apparatus, an electrode material deposited with heavy metals is used as the anode, and a titanium sheet is used as the cathode. MOFs catalytic membranes are synthesized by constant voltage 1.5V for 12 hours to obtain metal-organic framework-based stainless steel porous membranes.

[0084] Step 7: Prepare 1L of 5mg / L tetracycline solution, add 2.84g of NaSO4, and use electrocatalysis with a metal-organic framework-based stainless steel porous membrane as the anode and a titanium sheet as the cathode to degrade the pollutant in situ under an applied electric field. No current is applied for the first half hour for 30 minutes to eliminate adsorption, and then a constant current of 0.08A is applied for degradation for 120 minutes.

[0085] Example 6

[0086] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater specifically includes the following steps:

[0087] Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface; add 0.4M aniline monomer and 0.15M sodium dodecyl sulfate (SDS) to 200ml of pure water, and then ultrasonically dissolve them in an ultrasonic cleaner for 2 hours.

[0088] Step 2: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, polyaniline is electrosynthesized on the stainless steel mesh using a constant voltage of 3.5V. After 0.5 hours of synthesis, the material is removed and dried in a drying oven at 60℃ for 2 hours. After drying, the modified stainless steel material is removed.

[0089] Step 3: Dissolve PbCl2 (80 mg / L) and NaCl (0.02 mol / L) together in 200 ml of pure water, and sonicate for 10 minutes to obtain an electroplating wastewater solution;

[0090] Step 4: In a continuous flow apparatus, add electroplating wastewater solution, use modified stainless steel as cathode and titanium sheet as anode, and perform electrodeposition at a constant voltage of 10V for 2 hours. After reaching saturation, an electrode material with deposited heavy metals is obtained as the anode. Take 10ml of solution before and after electrodeposition and measure the metal ion concentration by ICP.

[0091] Step 5: Add 1,3,5-benzenetricarboxylic acid (8 mmol / L) and NaCl (20 mmol / L) to 2L of pure water, sonicate for 30 minutes to dissolve, and prepare 2L of 0.04M organic ligand solution;

[0092] Step 6: In a continuous flow apparatus, an electrode material deposited with heavy metals is used as the anode, and a titanium sheet is used as the cathode. MOFs catalytic membranes are synthesized by constant voltage 1.5V for 12 hours to obtain metal-organic framework-based stainless steel porous membranes.

[0093] Step 7: Prepare 1L of 5mg / L tetracycline solution, add 2.84g of NaSO4, and use electrocatalysis with a metal-organic framework-based stainless steel porous membrane as the anode and a titanium sheet as the cathode to degrade the pollutant in situ under an applied electric field. No current is applied for the first half hour for 30 minutes to eliminate adsorption, and then a constant current of 0.08A is applied for degradation for 120 minutes.

[0094] Example 7

[0095] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater specifically includes the following steps:

[0096] Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface; add 0.4M aniline monomer and 0.15M sodium dodecyl sulfate (SDS) to 200ml of pure water, and then ultrasonically dissolve them in an ultrasonic cleaner for 2 hours.

[0097] Step 2: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, polyaniline is electrosynthesized on the stainless steel mesh using a constant voltage of 3.5V. After 0.5 hours of synthesis, the material is removed and dried in a drying oven at 60℃ for 2 hours. After drying, the modified stainless steel material is removed.

[0098] Step 3: Dissolve NiCl2 (80mg / L) and NaCl (0.02mol / L) together in 200ml of pure water, and sonicate for 10 minutes to obtain an electroplating wastewater solution;

[0099] Step 4: In a continuous flow apparatus, add electroplating wastewater solution, use modified stainless steel as cathode and titanium sheet as anode, and perform electrodeposition at a constant voltage of 10V for 2 hours. After reaching saturation, an electrode material with deposited heavy metals is obtained as the anode. Take 10ml of solution before and after electrodeposition and measure the metal ion concentration by ICP.

[0100] Step 5: Add 1,3,5-benzenetricarboxylic acid (8 mmol / L) and NaCl (20 mmol / L) to 2L of pure water, sonicate for 30 minutes to dissolve, and prepare 2L of 0.04M organic ligand solution;

[0101] Step 6: In a continuous flow apparatus, an electrode material deposited with heavy metals is used as the anode, and a titanium sheet is used as the cathode. MOFs catalytic membranes are synthesized by constant voltage 1.5V for 12 hours to obtain metal-organic framework-based stainless steel porous membranes.

[0102] Step 7: Prepare 1L of 5mg / L tetracycline solution, add 2.84g of NaSO4, and use electrocatalysis with a metal-organic framework-based stainless steel porous membrane as the anode and a titanium sheet as the cathode to degrade the pollutant in situ under an applied electric field. No current is applied for the first half hour for 30 minutes to eliminate adsorption, and then a constant current of 0.08A is applied for degradation for 120 minutes.

[0103] Example 8

[0104] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater specifically includes the following steps:

[0105] Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface; add 0.4M aniline monomer and 0.15M sodium dodecyl sulfate (SDS) to 200ml of pure water, and then ultrasonically dissolve them in an ultrasonic cleaner for 2 hours.

[0106] Step 2: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, polyaniline is electrosynthesized on the stainless steel mesh using a constant voltage of 3.5V. After 0.5 hours of synthesis, the material is removed and dried in a drying oven at 60℃ for 2 hours. After drying, the modified stainless steel material is removed.

[0107] Step 3: Dissolve CoCl2 (80mg / L) and NaCl (0.02mol / L) together in 200ml of pure water, and sonicate for 10 minutes to obtain an electroplating wastewater solution;

[0108] Step 4: In a continuous flow apparatus, add electroplating wastewater solution, use modified stainless steel as cathode and titanium sheet as anode, and perform electrodeposition at a constant voltage of 10V for 2 hours. After reaching saturation, an electrode material with deposited heavy metals is obtained as the anode. Take 10ml of solution before and after electrodeposition and measure the metal ion concentration by ICP.

[0109] Step 5: Add 1,3,5-benzenetricarboxylic acid (8 mmol / L) and NaCl (20 mmol / L) to 2L of pure water, sonicate for 30 minutes to dissolve, and prepare 2L of 0.04M organic ligand solution;

[0110] Step 6: In a continuous flow apparatus, an electrode material deposited with heavy metals is used as the anode, and a titanium sheet is used as the cathode. MOFs catalytic membranes are synthesized by constant voltage 1.5V for 12 hours to obtain metal-organic framework-based stainless steel porous membranes.

[0111] Step 7: Prepare 1L of 5mg / L tetracycline solution, add 2.84g of NaSO4, and use electrocatalysis with a metal-organic framework-based stainless steel porous membrane as the anode and a titanium sheet as the cathode to degrade the pollutant in situ under an applied electric field. No current is applied for the first half hour for 30 minutes to eliminate adsorption, and then a constant current of 0.08A is applied for degradation for 120 minutes.

[0112] Example 9

[0113] A method for preparing metal-organic framework-based stainless steel porous membranes by recycling heavy metals from electroplating wastewater specifically includes the following steps:

[0114] Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface; add 0.4M aniline monomer and 0.15M sodium dodecyl sulfate (SDS) to 200ml of pure water, and then ultrasonically dissolve them in an ultrasonic cleaner for 2 hours.

[0115] Step 2: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, polypyrrole is electrosynthesized on the stainless steel mesh using a constant voltage of 3.5V. After 0.5 hours of synthesis, the material is removed and dried in a drying oven at 60℃ for 2 hours. After drying, the modified stainless steel material is removed.

[0116] Step 3: In a continuous flow device, add electroplating wastewater solution, use modified stainless steel as cathode and titanium sheet as anode, and perform electrodeposition at a constant voltage of 10V for 2 hours. After reaching saturation, an electrode material with deposited heavy metals is obtained as the anode. Take 10ml of solution before and after electrodeposition and measure the metal ion concentration by ICP.

[0117] Step 4: Add 1,3,5-benzenetricarboxylic acid (8 mmol / L) and NaCl (20 mmol / L) to 2L of pure water, sonicate for 30 minutes to dissolve, and prepare 2L of 0.04M organic ligand solution;

[0118] Step 5: In a continuous flow apparatus, an electrode material deposited with heavy metals is used as the anode, and a titanium sheet is used as the cathode. MOFs catalytic membranes are synthesized by constant voltage 1.5V for 12 hours to obtain metal-organic framework-based stainless steel porous membranes.

[0119] Step 6: Prepare 1L of 5mg / L tetracycline solution, add 2.84g of NaSO4, and use electrocatalysis with a metal-organic framework-based stainless steel porous membrane as the anode and a titanium sheet as the cathode to degrade the pollutant in situ under an applied electric field. No current is applied for the first half hour for 30 minutes to eliminate adsorption, and then a constant current of 0.08A is applied for degradation for 120 minutes.

[0120] II. Test Results

[0121] 2.1 Experimental Setup

[0122] Experimental apparatus: The experimental apparatus of the present invention includes an adjustable DC regulated power supply, a continuous flow device, and a peristaltic pump; the antibiotic concentration at the effluent is measured by liquid chromatography at flow rates of 8.33 ml / min and 16.66 ml / min.

[0123] 2.2 Experimental Methods and Results

[0124] 2.2.1 Test Methods

[0125] Solution samples (5 ml each time) need to be taken before and after electrodeposition. ICP analysis is performed on the samples to determine the metal ion concentration. The removal rate of metal ions by the electrode material is obtained by calculating the difference in metal ion concentration before and after electrodeposition. The formula is R = (C0 - C...). e ) / C0×100%, where C0 and C e These represent the concentrations of metal ions before and after electrodeposition.

[0126] 2.2.2 Results

[0127] (1) To investigate the growth of polypyrrole on the electrode material, the electrodes in step 2 of Examples 1-9 were observed by electron microscopy. The morphology before and after growth is shown in Figure (1), where (a) and (b) are electron micrographs of the stainless steel surface, and (c) and (d) are electron micrographs of the polypyrrole-coated surface. Compared with the bare stainless steel surface, the pore size of the stainless steel surface with polypyrrole is significantly smaller, and the entire network structure becomes more compact.

[0128] (2) To investigate the removal effect of the electrode material on metal ions, samples were taken from the solutions before and after electrodeposition in step 4 of Examples 1-9 for testing. The removal effects of each metal ion were as follows: Figure 2 As shown, the complex-breaking effect on various complexed metals is as follows: Figure 3 As shown.

[0129] (3) Figure 5 As shown in the XRD chart, peaks for HKUST-1, Pb-BTC, and Zn-BTC were basically observed in the XRD data.

[0130] (4) Figure 6 As shown, the electrocatalytic degradation of tetracycline (TC), norfloxacin (NOR), and sulfamethoxazole (SMX) showed that the effect in the first 30 minutes was the adsorption effect of the material. After half an hour of energization, the degradation effect reached saturation, and the antibiotic degradation efficiency was very high.

[0131] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing metal-organic framework-based stainless steel porous membranes by recovering heavy metals from electroplating wastewater, characterized in that, Specifically, the following steps are included: Step 1: Synthesize conductive polymers or conductive polymer composites on stainless steel mesh to obtain stainless steel mesh electrode materials modified with conductive polymers or conductive polymer composites. Specific steps are as follows: Step 1: Clean the stainless steel mesh using ultrasonic cleaning to ensure that there are no impurities on the electrode surface; Step 2: Prepare 200 ml of 0.4 M conductive polymer monomer or a mixture of conductive polymer monomer and other substances, and 0.15 M sodium dodecyl sulfate (SDS) electrolyte solution; Step 3: Using a stainless steel mesh as the anode and a titanium sheet as the cathode, a conductive polymer or conductive polymer composite material is electrosynthesized on the stainless steel mesh under constant voltage. After synthesis, the material is removed and dried in a drying oven at 60°C for 2 hours. The electrosynthesis conditions are either constant voltage 1.5V for 12 hours or constant voltage 3V for 30 minutes. The second step involves using the obtained conductive polymer or conductive polymer composite modified stainless steel mesh electrode material to electrodeposit the electroplating wastewater, thereby obtaining electrode material deposited with heavy metals. The specific steps are as follows: In a continuous flow device, 1 L of simulated electroplating wastewater or real electroplating wastewater solution containing complexed heavy metals is added. The conductive polymer or conductive polymer composite modified stainless steel mesh electrode material is used as the cathode, and a titanium sheet is used as the anode. Electrodeposition is performed at a constant voltage of 10 V for 2 hours to obtain electrode material deposited with heavy metals. 10 ml of solution is taken before and after electrodeposition and the metal ion concentration is measured by ICP. The third step involves converting the electrode material deposited with heavy metals into a MOF membrane in situ via electrosynthesis, thereby obtaining a metal-organic framework-based stainless steel porous membrane. Specifically, 8 mmol / L of 1,3,5-benzenetricarboxylic acid and 20 mmol / L of NaCl are added to 2 L of pure water and sonicated for 30 minutes to prepare 2 L of a 0.04 M organic ligand solution. Using the electrode material deposited with heavy metals obtained in the second step as the anode and a titanium sheet as the cathode, a MOF catalytic membrane is synthesized using a constant voltage of 1.5 V for 12 hours, yielding a metal-organic framework-based stainless steel porous membrane. The organic ligand is either 1,3,5-benzenetricarboxylic acid or terephthalic acid.

2. The method for preparing metal-organic framework-based stainless steel porous membranes by recovering heavy metals from electroplating wastewater according to claim 1, characterized in that: The first step conductive polymer is polypyrrole and / or polyaniline, and the conductive polymer composite material is polypyrrole / graphene oxide or polyaniline / 8-hydroxyquinoline.

3. The method for preparing metal-organic framework-based stainless steel porous membranes by recovering heavy metals from electroplating wastewater according to claim 2, characterized in that: The conductive polymer composite modified stainless steel mesh electrode material is a polypyrrole / graphene oxide composite modified stainless steel mesh electrode material. The synthesis method is to synthesize polypyrrole on a stainless steel mesh, and then deposit a layer of graphene oxide on the polypyrrole modified stainless steel mesh to obtain the polypyrrole / graphene oxide composite modified stainless steel mesh electrode material, so as to enhance the conductivity and electrochemical activity of stainless steel.

4. The method for preparing metal-organic framework-based stainless steel porous membranes by recovering heavy metals from electroplating wastewater according to claim 1, characterized in that: In the second step, the electroplating wastewater contains one or more of Cu, Pb, Ni, and Co, and the heavy metals in the electrode material deposited with heavy metals are elemental heavy metals or metal oxides.

5. The method for preparing metal-organic framework-based stainless steel porous membranes by recovering heavy metals from electroplating wastewater according to claim 1, characterized in that: The 0.4 M conductive polymer monomer is either a 0.4 M pyrrole monomer or a 0.4 M aniline monomer, and the other substances are graphene oxide and / or 8-hydroxyquinoline. In the mixed solution, the conductive polymer monomer and other substances are all 0.4 M.

6. The application of a metal-organic framework-based stainless steel porous membrane prepared by the method for preparing a metal-organic framework-based stainless steel porous membrane according to any one of claims 1-5 in in-situ degradation of pollutants, characterized in that: Using an electrocatalytic method, a metal-organic framework-based stainless steel porous membrane is used as the anode and a titanium sheet is used as the cathode to degrade pollutants in situ under a constant current electric field of 0.08A.

7. The application according to claim 6, characterized in that: The pollutants are tetracycline, norfloxacin, and sulfamethoxazole, and the applied electric field is a constant current of 0.08A.

Images