Three-dimensional corrugated membrane assembly and preparation method thereof

Abstract

The invention discloses a three-dimensional corrugated membrane module and a preparation method thereof, the thickness of a concentration polarization layer is effectively reduced, the three-dimensional corrugated membrane module comprises a membrane substrate with a periodic wave structure, and a non-parallel included angle is formed between the corrugated direction of the wave structure and the flow direction of a predetermined fluid; cross-scale pores are distributed in the membrane substrate and comprise macroscopic corrugated valley bottom pores, mesoscopic corrugated peak top pores and microscopic nanofiber interwoven pores; the membrane base body is composed of a polymer substrate, the polymer substrate comprises a dynamic covalent network and an ion conduction group, the structure is novel, the concept is ingenious, operation is easy and convenient, the purpose of reducing energy consumption is effectively achieved, the self-repairing function of a membrane assembly is increased, the ion transmission efficiency is improved, the membrane pollution rate is reduced, and the service life of the membrane assembly is prolonged. And better anti-pollution performance is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemistry and relates to a three-dimensional corrugated membrane component and a preparation method thereof. Background Art

[0002] Proton exchange membrane, also known as proton membrane or hydrogen ion exchange membrane, is an ion-selective membrane. Located at the center of the membrane electrode, the proton exchange membrane acts as a proton transfer carrier to transfer protons generated in the anode catalyst layer to the cathode catalyst layer, where they react with oxygen to generate water.

[0003] Traditional proton exchange membranes (such as Nafion) face problems in electrochemical systems, such as severe concentration polarization caused by their planar structure, low mass transfer efficiency, easy contamination, and high maintenance costs. Especially in bioelectrochemical fields such as microbial electrolysis cells, biofilm adhesion and chemical degradation significantly shorten the membrane life.

[0004] Therefore, a three-dimensional corrugated membrane component and its preparation method that can integrate the functions of proton conduction, anti-pollution and structural strengthening are needed to solve the above problems. Summary of the Invention

[0005] In response to the above problems, the present invention proposes a three-dimensional corrugated membrane assembly and a preparation method thereof, which effectively solves the problems in the prior art.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A three-dimensional corrugated membrane assembly, comprising:

[0008] A membrane substrate having a periodic wave structure, wherein the wave direction of the wave structure is at a non-parallel angle to the predetermined fluid flow direction;

[0009] The membrane substrate is provided with cross-scale pores, which include macroscopic corrugation valley pores, mesoscopic corrugation peak pores and microscopic nanofiber interwoven pores;

[0010] The membrane matrix is ​​composed of a polymer substrate, which includes a dynamic covalent network and ion-conducting groups;

[0011] The outer side of the membrane matrix is ​​provided with a nano-enhanced phase, which includes graphene oxide and microcapsules that can respond to pH and are loaded on the surface of the membrane matrix. The microcapsules have a polyelectrolyte shell and a core containing a repair monomer.

[0012] Preferably, the wavelength of the periodic wave structure is 2-4 mm, the wave height is 1.0-1.5 mm, and the angle between the wave direction and the predetermined fluid flow direction is 30° to 60°.

[0013] Preferably, the pore size of the macroscopic corrugation valley is 50-100 μm; the pore size of the mesoscopic corrugation peak is 5-10 μm; and the pore size of the microscopic membrane body is 0.22 μm.

[0014] Preferably, the polymer substrate is composed of a polyethersulfone-polydopamine graft copolymer as the main chain, the dynamic covalent network is composed of disulfide bonds and borate bonds, and the ion-conducting groups include grafted sulfonic acid groups (-SO3H) and quaternary ammonium groups (-N + (CH3)3);

[0015] The pH response point of the boronate ester bond is 7.4±0.2 or 9.0±0.1.

[0016] Preferably, in the nano-enhanced phase:

[0017] Graphene oxide is anchored in the cross-scale pores;

[0018] The density of the microcapsules is 200-220 per mm 2 ;

[0019] The polyelectrolyte shell is formed by alternately depositing 10-30 layers of polyelectrolytes, and the core comprises a repair monomer containing a thiol group and magnetic nanoparticles.

[0020] In addition, the present invention also provides a method for preparing a three-dimensional corrugated membrane assembly, which is applied to the above-mentioned three-dimensional corrugated membrane assembly and comprises the following steps:

[0021] Step S1, preparing a gradient pore nanofiber substrate by magnetic field-assisted electrospinning, and compounding it with graphene oxide;

[0022] Step S2: constructing a dynamic covalent network containing ion-conducting groups:

[0023] The product of step S1 is sequentially subjected to the following steps: step S21, sulfonation to introduce sulfonic acid groups; step S22, ultraviolet light grafting of quaternary ammonium groups; step S23, disulfide bond crosslinking and construction of borate bonds;

[0024] Step S3, loading pH-responsive microcapsules by microfluidics technology;

[0025] Step S4: hot-pressing the corrugated structure and activating the self-repairing function.

[0026] Preferably, the step S1 specifically includes:

[0027] Step S11, electrospinning a polyethersulfone and polydopamine copolymer solution under a 0.1-1 T magnetic field to form a bottom dense layer, a middle transition layer, and a top loose layer;

[0028] Step S12, immersing the fiber membrane in a graphene oxide dispersion;

[0029] In step S11, the magnetic field control during electrospinning includes the following steps:

[0030] Step A: The initial magnetic field direction is set to vertical, the magnetic field strength is 0.5 T, and a dense layer with a porosity of 40% is formed;

[0031] Step B, rotating the magnetic field to a 45° inclination and translating the roller to form a transition layer with a porosity of 65%;

[0032] Step C: The rotating magnetic field is horizontal, the magnetic field strength is 0.2 T, and the rotating drum forms a loose layer with a porosity of 80%.

[0033] Preferably, step S3 includes the following steps:

[0034] Step S31: alternately injecting polyelectrolyte solution through coaxial microfluidics to form a microcapsule shell.

[0035] Step S32: curing the core material containing the repair monomer under a rotating magnetic field and ultraviolet light.

[0036] Step S33, 200-220 pieces / mm 2 Density loaded microcapsules.

[0037] Preferably, step S4 includes the following steps:

[0038] Step S41, in the Fe-containing 3+ and ascorbic acid solution permeate catalytic ions, of which Fe 3+ Concentration 0.1-0.3M, ascorbic acid and Fe 3+ Molar ratio 1.2:1-1.5:1;

[0039] Step S42: using a mold to hot-press the corrugated structure at 160-200° C., with a center pressure of 8 MPa, an edge pressure of 5 MPa, and a time of 10-15 minutes.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. The present invention has a wave structure, which can reduce the thickness of the concentration polarization layer by inducing turbulence and improve the mass transfer efficiency.

[0042] 2. The present invention has a polymer base, the main chain of which is composed of a polyethersulfone-polydopamine graft copolymer, and contains disulfide bonds and borate bonds. The disulfide bonds provide mechanical strength, and the borate bonds achieve pH-responsive dissociation, which can achieve better effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a partial structural diagram of the present invention. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] The following is combined with Figure 1 The specific embodiments of the present invention are described in further detail.

[0046] A three-dimensional corrugated membrane component, such as Figure 1 As shown, in order to solve the problems of severe concentration polarization, low mass transfer efficiency, easy pollution and high maintenance cost of traditional proton exchange membranes in electrochemical systems, the following are included:

[0047] The membrane substrate has a periodic wave structure, wherein the corrugation direction of the wave structure is non-parallel to the predetermined fluid flow direction; the wavelength of the periodic wave structure is 2-4 mm, preferably 3 mm, the wave height is 1.0-1.5 mm, preferably 1.2 mm, and the angle between the corrugation direction and the predetermined fluid flow direction is 30°-60°, preferably 45°. The mass transfer coefficient is the highest at an inclination angle of 45°, reaching 5.8×10 -5 m / s; the wave structure can reduce the thickness of the concentration polarization layer to 50μm by inducing turbulence;

[0048] Experimental results of the corrugation inclination angle show that the concentration polarization layer is the thinnest at a 45° inclination angle, and the mass transfer efficiency is improved compared to the traditional vertical structure. The specific data are as follows:

[0049]

[0050] The membrane substrate is provided with cross-scale pores, which include macroscopic corrugation valley pores, mesoscopic corrugation peak pores and microscopic nanofiber interwoven pores;

[0051] The pore size of the macroscopic corrugation valley is 50-100 μm, which is used to promote mass transfer of the main solution and increase the diffusion coefficient by 3.8 times; the pore size of the mesoscopic corrugation peak is 5-10 μm, which is used to form a local high electric field intensity gradient; the pore size of the microscopic membrane body is 0.22 μm, which is used to achieve selective ion transport;

[0052] The membrane matrix is ​​composed of a polymer substrate, which includes a dynamic covalent network and ion-conducting groups;

[0053] The polymer substrate is composed of a polyethersulfone-polydopamine graft copolymer as the main chain, the dynamic covalent network is composed of disulfide bonds and borate bonds, the disulfide bonds provide mechanical strength, the borate bonds achieve pH response dissociation, and the ion conductive groups include grafted sulfonic acid groups (-SO3H) and quaternary ammonium groups (-N + (CH3)3), the sulfonic acid group builds the proton channel, and the quaternary ammonium group optimizes the charge distribution;

[0054] The pH response point of the boronate ester bond is 7.4±0.2 or 9.0±0.1, and the pH response point is precisely controlled by the catechol group / boric acid molar ratio of 1:1-1:1.5, the selection of 4-nitrophenylboronic acid / phenylboronic acid, and the buffer ionic strength of 0.1-0.5M. The dynamic covalent network triggers the dissociation of the boronate ester bond when the pH is greater than 8.5, and the disulfide bond exchange reaction (SS→2S - ) Achieve self-healing of micro cracks within 30 minutes;

[0055] The outer side of the membrane substrate is provided with a nano-reinforced phase, which includes graphene oxide and pH-responsive microcapsules loaded on the surface of the membrane substrate for achieving damage self-repair. The microcapsules have a polyelectrolyte shell (20 layers of PAH / PSS double-layer structure) and a core containing repair monomers (PETMP monomers and Fe3O4 nanoparticles);

[0056] In the nano-enhanced phase:

[0057] Graphene oxide is anchored in the cross-scale pores through hydrogen bonds between the PDA catechol groups and the GO oxygen-containing functional groups;

[0058] The density of the microcapsules is 200-220 per mm 2 , preferably 210 / mm 2 , ensuring the coverage efficiency of the repair agent;

[0059] The polyelectrolyte shell is formed by alternating deposition of 10-30 layers of polyelectrolytes, preferably 20 layers, wherein the shell has a rupture strength of 15 MPa when the layers are 20 layers. The core includes a thiol-containing repair monomer (PETMP) and magnetic nanoparticles (oleic acid-modified Fe3O4, magnetic field-induced enrichment);

[0060] It should be noted that the microcapsules degraded at a local pH of 8.5, and the released PETMP monomers reacted with the disulfide bonds in the dynamic network to form sulfhydryl-ene click reactions, binding to Fe 3+ / ascorbic acid redox system initiated polymerization and restored 98% of the proton flux of macroscopic damage (<200 μm) within 2 hours.

[0061] In addition, the present invention also discloses a method for preparing a three-dimensional corrugated membrane assembly, which is applied to the above-mentioned three-dimensional corrugated membrane assembly and includes the following steps:

[0062] Step S1, preparing a gradient pore nanofiber substrate by magnetic field-assisted electrospinning, and compounding it with graphene oxide;

[0063] Step S1 specifically includes:

[0064] Step S11, electrospinning a polyethersulfone and polydopamine copolymer solution under a 0.1-1 T magnetic field to form a bottom dense layer, a middle transition layer, and a top loose layer;

[0065] Step S12, immersing the fiber membrane in a graphene oxide dispersion;

[0066] In step S11, the magnetic field control during electrospinning includes the following steps:

[0067] Step A: The initial magnetic field direction is set to vertical, the magnetic field strength is 0.5 T, and a dense layer with a porosity of 40% is formed;

[0068] Step B, rotating the magnetic field to a 45° inclination and translating the roller to form a transition layer with a porosity of 65%;

[0069] Step C: The rotating magnetic field is horizontal, the magnetic field strength is 0.2 T, and the rotating drum forms a loose layer with a porosity of 80%;

[0070] Step S2: constructing a dynamic covalent network containing ion-conducting groups:

[0071] The output of step S1 is subjected to the following steps in sequence:

[0072] Step S21, sulfonation to introduce sulfonic acid groups; in SO3 vapor at 110°C for 4 hours to establish a continuous proton channel;

[0073] Step S22, ultraviolet light grafting of quaternary ammonium groups; ultraviolet initiation in a DMC solution under nitrogen protection to form alternating distribution of sulfonic acid / quaternary ammonium microdomains;

[0074] Step S23, disulfide bond cross-linking and borate ester bond construction; 4,4'-diphenylamine disulfide ethanol solution was irradiated with UV light for 30 minutes and then esterified with pH 9.2 borax buffer;

[0075] Step S3, loading pH-responsive microcapsules by microfluidic technology, specifically comprising the following steps:

[0076] Step S31: alternately injecting a polyelectrolyte solution of PAH 0.1 wt% / pH 5.0 / 200±10 μS / cm + PSS 0.2 wt% / pH 7.4 / 450±20 μS / cm through coaxial microfluidics at a flow rate of 1 mL / min to form a microcapsule shell;

[0077] Step S32: curing the core material containing the repair monomer (PETMP+3% photoinitiator+1% oleic acid Fe3O4+0.1% bromocresol purple) under a rotating magnetic field (50 Hz, 0.5 T) and ultraviolet light (365 nm);

[0078] Step S33, 200-220 pieces / mm 2 The microcapsules were densely loaded and anchored in vacuum curing at 60°C;

[0079] It should be noted that the bromocresol purple indicator was used to monitor the release of the repair agent in real time (from yellow to purple when pH>7.4), and the Fe3O4 nanoparticles were enriched toward the core under the rotating magnetic field, which increased the concentration gradient of the repair agent;

[0080] Step S4, in order to simultaneously realize structural forming and function activation, hot pressing the corrugated structure and activating the self-repair function, includes the following steps:

[0081] Step S41, in the Fe-containing 3+ and ascorbic acid solution permeate catalytic ions, of which Fe 3+ Concentration 0.1-0.3M, ascorbic acid and Fe 3+ Molar ratio 1.2:1-1.5:1;

[0082] Step S42: using a mold to hot-press a corrugated structure at 160-200° C., with a center pressure of 8 MPa, an edge pressure of 5 MPa, and a time of 10-15 minutes; the hot-pressing temperature is preferably 180° C.;

[0083] It should be noted that step S4 makes the corrugated structure (wavelength 3 mm / wave height 1.2 mm) and the dynamic network synchronously stable, and prolongs the self-repair function to extend the maintenance cycle.

[0084] The specific operation method of the above-mentioned method for preparing a three-dimensional corrugated membrane assembly in this embodiment is as follows:

[0085] Polyethersulfone (PES) was dissolved in N-methylpyrrolidone (NMP), and dopamine hydrochloride was added. Oxidative polymerization was initiated under alkaline conditions (pH 8.5) to form a PES-PDA graft copolymer (the mass ratio of polyethersulfone (PES) to dopamine hydrochloride ranged from 1:0.1 to 1:0.5. The typical mass ratio of polyethersulfone (PES) to N-methylpyrrolidone (NMP) ranged from 1:4 to 1:10). The solution was then electrospun under a high-voltage electric field of 20 kV to form nanofiber membranes with diameters of 80-150 nm. The preformed nanofiber membrane was placed in a vacuum impregnation tank and injected with a graphene oxide (GO) dispersion (graphene oxide was ultrasonically dispersed in N,N-dimethylformamide (DMF) at a concentration of 0.5wt%, with 0.1wt% hexadecyltrimethylammonium bromide (CTAB) added to improve interfacial compatibility). This allowed the GO to penetrate the interfiber gaps, where it was anchored by hydrogen bonds between the catechol groups of polydopamine (PDA) and the oxygen-containing functional groups (-COOH, -OH) of the GO. Simultaneously, a magnetic field-assisted device, controlled by a 0.5T permanent magnet array, formed a three-dimensional framework with a gradient porosity.

[0086] Afterwards, a Halbach permanent magnet array (surface magnetic field strength 0.5T) was placed parallel to the bottom of the electrospinning receiving drum (with a spacing of 10cm). The initial magnetic field direction was vertically upward (Z axis) and the drum was stationary. After starting electrospinning (PES-PDA solution containing 0.5wt% Fe3O4, voltage 20kV), the magnetic fibers were closely arranged along the magnetic field lines under the action of the Lorentz force, forming a bottom dense layer (porosity 40%). Subsequently, the magnet array was rotated by a motor at a rate of 5° / min, so that the magnetic field direction gradually changed to 45° tangential to the drum. The drum was simultaneously translated away from the magnetic field source at 1mm / s, inducing the fibers to transition from order to disorder with the magnetic field gradient (porosity increased to 65%). Finally, the horizontal magnetic field mode was switched to 0.2T, XY plane, and the drum was driven to rotate at 10rpm. The fibers were randomly deposited to form a top loose layer (porosity 80%), obtaining a fiber skeleton.

[0087] The fiber skeleton was exposed to SO3 vapor and sulfonated at 110°C for 4 hours to introduce sulfonic acid groups (-SO3H) to form continuous proton channels. Subsequently, the fiber skeleton was immersed in a methacryloyloxyethyltrimethylammonium chloride (DMC) solution under nitrogen protection, and quaternary ammonium groups (-N+(CH3)3) were grafted through ultraviolet-induced free radical polymerization to form sulfonic acid / quaternary ammonium micro-regions distributed alternately along the fiber axis. Then, it was immersed in an ethanol solution containing 4,4'-dithiodiphenylamine and exposed to ultraviolet light (365nm, 10mW / cm 2, 30 min) to induce disulfide (SS) crosslinking, forming a gradient network with a dense surface layer and a loose bottom layer. Finally, phenylboronic acid ester bonds were introduced in borax buffer (pH 9.2), and pH-responsive sites were constructed by reversible esterification of the catechol group of PDA with boronic acid.

[0088] The pH response point is regulated as follows:

[0089] Through the reversible esterification reaction of catechol group with phenylboronic acid:

[0090]

[0091] The equilibrium constant (Keq) of a reaction is directly related to pH, and Keq is regulated by the following factors:

[0092]

[0093] When the target pH is 7.4: use 4-nitrophenylboronic acid (molar ratio 1:1.5), buffer pH = 8.0, and the response point can be adjusted to 7.4 ± 0.2;

[0094] When the target pH is 9.0: phenylboronic acid (molar ratio 1:1) is used, the buffer pH is 9.2, and the response point is 9.0±0.1.

[0095] Then, pH-responsive microcapsules were embedded. First, the core material solution was prepared by dissolving pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), a photoinitiator (3wt%), oleic acid-modified Fe304 nanoparticles (1wt%), and bromocresol purple (0.1wt%) in anhydrous ethanol and ultrasonically dispersing them evenly. At the same time, the shell solution, polyallylamine hydrochloride (PAH, 0.1wt%, pH 5.0) and sodium polystyrene sulfonate (PSS, 0.2wt%, pH 7.4) aqueous solutions were prepared. The two solutions were vacuum filtered through a 0.22μm nylon filter membrane to remove undissolved particles and bubbles. The final conductivity of the PAH solution was controlled at 200±10μS / cm, and the conductivity of the PSS solution was 450±20μS / cm to ensure charge density matching during alternating deposition of polyelectrolytes and avoid defects in the microcapsule shell. Subsequently, the core material solution was injected into the inner tube of the coaxial glass capillary microfluidic chip (flow rate of 0.5 mL / min), and the PAH and PSS solutions were alternately injected into the outer tube (flow rate of 1 mL / min). A double emulsion was formed by coaxial flow focusing and allowed to stand in a crosslinking bath containing 2% CaCl2 (pH 8.5) for 15 minutes. 20 layers of PAH / PSS shell were deposited layer by layer to form a pH-responsive shell. The emulsion was then transferred to a quartz reaction cell, deoxygenated with nitrogen, and then a rotating magnetic field (50 Hz, 0.5 T) was applied. At the same time, 365 nm ultraviolet light was irradiated for 20 minutes to trigger PETMP crosslinking, causing Fe304 nanoparticles to be enriched in the center of the core. The microcapsules were collected by centrifugation, washed with deionized water and ethanol three times to remove unreacted products, and then freeze-dried in vacuum (-50°C, 10 Pa, 24 h) to obtain magnetic microcapsules. Finally, the microcapsules were 2×10 4 Pieces / mm 2 The density is loaded on the membrane surface and solidified and anchored under vacuum conditions at 60°C to ensure that the repair agent is released along the fluid path when damaged;

[0096] When depositing the PAH / PSS shell, the number of times and thickness show a linear relationship:

[0097] T=n·d bilayer

[0098] Where: n is the number of bilayers (i.e., half of the deposition times, e.g., 20 layers of PAH / PSS correspond to 10 bilayers);

[0099] d bilayer is the average thickness of each bilayer.

[0100] The PAH solution was prepared by dissolving PAH powder in deionized water to prepare a 0.1 wt% solution (i.e., 1 g PAH in 999 g water), stirring the solution magnetically (500 rpm, 30 min) until complete dissolution, and then adjusting the pH to 5.0 with 0.1 M HCl to enhance amino protonation.

[0101] The polystyrene sulfonate (PSS) solution was prepared by dissolving polystyrene sulfonate (PSS) powder in deionized water to make a 0.2 wt% solution (2 g PSS in 998 g water), stirring to dissolve, and then adjusting the pH to 7.4 with 0.1 M NaOH to maintain dissociation of the sulfonic acid groups.

[0102] Then activate the self-repairing property: immerse the three-dimensional film in a solution containing Fe 3+ In a redox solution of 1% PEG / ascorbic acid, the catalytic ions penetrated the membrane through vacuum pressure, followed by pre-curing (80°C, 2h) in a nitrogen atmosphere to stabilize the bonding structure. When the membrane was damaged, the local pH rose above 8.5, triggering degradation of the microcapsule shell. The released PETMP monomers, under the stimulation of ultraviolet light (365nm), underwent a thiol-ene click reaction with the disulfide bonds in the dynamic network. Simultaneously, the borate ester bonds reorganized in the acidic exudate, achieving self-repair of microcracks (<10μm) within 30 minutes and in-situ regeneration of macrocracks (<200μm) within 2 hours. After repair, the proton flux recovery rate exceeded 98%.

[0103] Finally, hot pressing is performed using a 3D-printed titanium alloy mold and gradient pressure control. At 180°C, 8MPa center pressure and 5MPa edge pressure are applied for 10-15 minutes. The nanofiber skeleton is embossed into a 45° corrugated structure with a wavelength of 3mm and a wave height of 1.2mm.

[0104] Through the above preparation method, the proton migration path can be optimized:

[0105] The sulfonic acid group (-SO3H) constructs a continuous proton channel and achieves efficient proton hopping conduction through a hydrogen bond network. The π-π electron network of graphene oxide (GO) provides an auxiliary conduction path, synergistically increasing the proton flux to 4.7×10 -2 S / cm (40% higher than Nafion membrane), reducing the interfacial charge transfer resistance.

[0106] The corrugated structure forms a spiral ion channel (path length shortened to 62% of that of a planar membrane), combined with surface zeta potential control (dynamically adjustable from -35mV to +25mV), achieving:

[0107]

[0108] The effective diffusion coefficient D eff Improved by 2.4 times, the boundary layer thickness δ eff Reduced by 58%, effective area A enh The comprehensive proton flux is increased to 6.7 times that of traditional membranes;

[0109] Through the above preparation method, the self-repair mechanism and macro damage repair ability are increased:

[0110] Self-repair mechanism: When microcracks (<10 μm) appear in the membrane, changes in the environmental pH (such as local acid accumulation) trigger the disulfide bond exchange reaction ( ), the cracks self-healed within 30 minutes.

[0111] Macro damage repair: Mechanical stress (critical stress > 15MPa) damages the microcapsules, causing them to rupture, triggering the release of repair monomers (containing mercapto vinyl monomers) from the microcapsules. 3+ In-situ polymerization was achieved using a 1% hydroxyethyl ester (HA / ascorbic acid redox system) (98% flux recovery within 2 hours). The self-repair function extended the maintenance cycle from 3 months to 2 years, reducing operating costs by 58%.

[0112] The present invention has a novel structure, ingenious conception, and simple and convenient operation. Through this design, the thickness of the concentration polarization layer is effectively reduced, thereby achieving the purpose of reducing energy consumption, increasing the self-repair function of the membrane component, increasing the ion transmission efficiency, reducing the rate of membrane fouling, and achieving better anti-pollution performance.

[0113] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A three-dimensional corrugated membrane assembly, characterized in that: include: A membrane substrate having a periodic wave structure, wherein the wave direction of the wave structure is at a non-parallel angle to the predetermined fluid flow direction; The membrane substrate is provided with cross-scale pores, which include macroscopic corrugation valley pores, mesoscopic corrugation peak pores and microscopic nanofiber interwoven pores; The membrane matrix is ​​composed of a polymer substrate, which includes a dynamic covalent network and ion-conducting groups; The outer side of the membrane matrix is ​​provided with a nano-enhanced phase, which includes graphene oxide and microcapsules that can respond to pH and are loaded on the surface of the membrane matrix. The microcapsules have a polyelectrolyte shell and a core containing a repair monomer.

2. A three-dimensional corrugated membrane assembly according to claim 1, characterized in that: The wavelength of the periodic wave structure is 2-4 mm, the wave height is 1.0-1.5 mm, and the angle between the wave direction and the predetermined fluid flow direction is 30°-60°.

3. The three-dimensional corrugated membrane assembly according to claim 1, characterized in that: The pore size of the macroscopic corrugation valley is 50-100 μm; the pore size of the mesoscopic corrugation peak is 5-10 μm; and the pore size of the microscopic membrane body is 0.22 μm.

4. The three-dimensional corrugated membrane assembly according to claim 1, characterized in that: The polymer substrate is composed of a polyethersulfone-polydopamine graft copolymer as the main chain, the dynamic covalent network is composed of disulfide bonds and borate bonds, and the ion-conducting groups include grafted sulfonic acid groups (-SO3H) and quaternary ammonium groups (-N + (CH3)3); The pH response point of the boronate ester bond is 7.4±0.2 or 9.0±0.

1.

5. The three-dimensional corrugated membrane assembly according to claim 1, characterized in that: In the nano-enhanced phase: Graphene oxide is anchored in the cross-scale pores; The density of the microcapsules is 200-220 per mm 2 ; The polyelectrolyte shell is formed by alternately depositing 10-30 layers of polyelectrolytes, and the core comprises a repair monomer containing a thiol group and magnetic nanoparticles.

6. A method for preparing a three-dimensional corrugated membrane assembly, applied to a three-dimensional corrugated membrane assembly according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step S1, preparing a gradient pore nanofiber substrate by magnetic field-assisted electrospinning, and compounding it with graphene oxide; Step S2: constructing a dynamic covalent network containing ion-conducting groups: The product of step S1 is sequentially subjected to the following steps: step S21, sulfonation to introduce sulfonic acid groups; step S22, ultraviolet light grafting of quaternary ammonium groups; step S23, disulfide bond crosslinking and construction of borate bonds; Step S3, loading pH-responsive microcapsules by microfluidics technology; Step S4: hot-pressing the corrugated structure and activating the self-repairing function.

7. The method for preparing a three-dimensional corrugated membrane assembly according to claim 6, characterized in that: The step S1 specifically includes: Step S11, electrospinning a polyethersulfone and polydopamine copolymer solution under a 0.1-1 T magnetic field to form a bottom dense layer, a middle transition layer, and a top loose layer; Step S12: Immersing the fiber membrane in the graphene oxide dispersion.

8. The method for preparing a three-dimensional corrugated membrane assembly according to claim 7, characterized in that: In step S11, the magnetic field control during electrospinning includes the following steps: Step A: The initial magnetic field direction is set to vertical, the magnetic field strength is 0.5 T, and a dense layer with a porosity of 40% is formed; Step B, rotating the magnetic field to a 45° inclination and translating the roller to form a transition layer with a porosity of 65%; Step C: The rotating magnetic field is horizontal, the magnetic field strength is 0.2 T, and the rotating drum forms a loose layer with a porosity of 80%.

9. The method for preparing a three-dimensional corrugated membrane assembly according to claim 6, characterized in that: The step S3 comprises the following steps: Step S31: alternately injecting polyelectrolyte solution through coaxial microfluidics to form a microcapsule shell. Step S32: curing the core material containing the repair monomer under a rotating magnetic field and ultraviolet light. Step S33, 200-220 pieces / mm 2 Density loaded microcapsules.

10. The method for preparing a three-dimensional corrugated membrane assembly according to claim 6, characterized in that: The step S4 comprises the following steps: Step S41, in the Fe-containing 3+ and ascorbic acid solution permeate catalytic ions, of which Fe 3+ Concentration 0.1-0.3M, ascorbic acid and Fe 3+ Molar ratio 1.2:1-1.5:1; Step S42: using a mold to hot-press the corrugated structure at 160-200° C., with a center pressure of 8 MPa, an edge pressure of 5 MPa, and a time of 10-15 minutes.

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