Bionic self-cleaning water filtering core layer as well as preparation method and application thereof

Abstract

The invention discloses a bionic self-cleaning water filtering core layer and a preparation method and application thereof, and belongs to the technical field of filtering, the bionic self-cleaning water filtering core layer comprises a porous supporting layer, a filtering functional layer and a self-cleaning layer; wherein the filtering functional layer is compounded on the porous supporting layer; the filtering functional layer comprises nanofiber grids which are interwoven with one another and bionic adhesive hydrogel which is filled in the nanofiber grids; the self-cleaning layer comprises a drivable artificial cilia array, and the drivable artificial cilia array vertically penetrates through the filtering function layer. According to the core layer provided by the invention, the filtering efficiency, the self-cleaning capability and the structural stability are remarkably improved through parameterized design, the dependence on a chemical cleaning agent and the need for frequent maintenance are also reduced through the long-acting operation characteristic of the core layer, and the core layer has remarkable environment-friendly and energy-saving advantages while the service life is prolonged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of filtration, and particularly relates to a biomimetic self-cleaning water filtration core layer and a preparation method and application thereof. BACKGROUND

[0002] Current mainstream filtration technologies, such as microfiltration and ultrafiltration, mainly have the core principle of mechanical screening, that is, particles larger than the pore size are intercepted through the micropores on the membrane. However, the defect is that during operation, pollutants accumulate on the membrane surface and in the pore channel, thereby causing the filtration flux to decrease, the operating pressure to increase, and frequent chemical cleaning. This not only increases the operation cost and energy consumption, but also shortens the service life of the membrane. Therefore, developing a new type of filtration design that can resist pollution and achieve self-cleaning from the essence has become a technical problem to be solved.

[0003] In nature, the gill filtration system of bivalves (such as mussels and oysters) is a perfect example of high efficiency and anti-clogging, which exhibits very excellent performance. Through the synergistic effect of "mucus capture" and "cilia transport", the bivalves not only filter food efficiently, but also continuously and directionally remove the intercepted particles, thereby realizing long-term stable operation of the system.

[0004] Therefore, how to provide an artificial filter layer that mimics the mechanism of bivalve organisms to achieve self-cleaning is a technical problem to be solved by those skilled in the art. SUMMARY

[0005] To solve the above technical problems, the present application provides a biomimetic self-cleaning water filtration core layer and a preparation method and application thereof.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A biomimetic self-cleaning water filtration core layer, comprising a porous support layer, a filtration functional layer, and a self-cleaning layer. The filtration functional layer is compounded on the porous support layer. The filtration functional layer comprises a nanofiber grid interwoven with each other and a biomimetic adhesive hydrogel filled in the nanofiber grid. The self-cleaning layer comprises a drivable artificial cilium array, and the drivable artificial cilium array vertically penetrates the filtration functional layer.

[0007] Preferably, the porous support layer is a porous membrane with a three-dimensional interpenetrating pore structure prepared from polyvinylidene fluoride.

[0008] Beneficial effects: The structure can ensure low resistance of water flow and provide stable anchoring points for the upper layer.

[0009] The average pore diameter of the porous support layer is 100±20 μm, the porosity is 85-90%, and the thickness is 2.0 mm.

[0010] Beneficial effects: The average diameter range is designed to ensure excellent permeability while preventing the upper layer of nanofibers from being squeezed or penetrated under water pressure, and the high porosity minimizes the pressure loss of water flow through this layer. The above thickness provides the necessary mechanical strength and rigidity for the entire filter core.

[0011] Preferably, the biomimetic adhesive hydrogel is a catechol group-rich polymer hydrogel. Preferably, the solid content of the polymer hydrogel is 10-15%, and the density of the contained catechol groups is 8-12 μmol / cm 3 .

[0012] Preferably, the polymer hydrogel is a polydopamine hydrogel.

[0013] Beneficial effects: Dopamine can self-polymerize under mild conditions and firmly adhere to various surfaces, perfectly filling the voids of the nanofiber grid, and the catechol group is the core skeleton of dopamine, which can capture nanoscale pollutants such as heavy metal ions, organic dyes, and microorganisms through various interactions such as coordination bonds, hydrogen bonds, and stacking. And the above solid content ensures that the hydrogel has good adhesion and mechanical strength while maintaining a porous structure in a fully swollen state, allowing water molecules to pass through.

[0014] Preferably, the nanofibers in the nanofiber grid are positively charged polymer nanofibers.

[0015] Preferably, the positively charged polymer nanofibers are chitosan / polyethyleneimine composites.

[0016] Beneficial effects: Both chitosan and polyethyleneimine are positively charged and can effectively adsorb negatively charged colloids, viruses, and organic macromolecules in water through electrostatic interaction.

[0017] Preferably, the filter pore size D of the filter functional layer satisfies D = η · d f ; Where η is the pore size coefficient, and its value range is 0.1-0.5; d f is the average diameter of the nanofibers in the nanofiber grid, and d f is 200±50 nm; Beneficial effects: The average diameter range of this nanofiber can form a grid dense enough to intercept sub-micron particles, while retaining a high porosity, and by adjusting the electrospinning process parameters, the η value can be controlled, thus achieving precise design of the filtration accuracy.

[0018] The thickness h f of the filter functional layer satisfies hf =k·L; wherein k is a thickness ratio coefficient, and k is in the range of 1.0-2.5; L is the length of the drivable artificial cilium.

[0019] Beneficial effect: The thickness is designed in coordination with the length of the artificial cilium of the self-cleaning layer, which ensures that the artificial cilium has sufficient length to be exposed to the water flow and effectively swing, and at the same time, the anchoring depth is sufficient to ensure stability under long-term driving.

[0020] Preferably, the drivable artificial cilium is a magnetic material, and the drivable artificial cilium is driven to swing synchronously by applying an alternating magnetic field.

[0021] The inductive intensity of the alternating magnetic field is 50-80 mT, and the frequency is 5-20 Hz.

[0022] Beneficial effect: The alternating magnetic field can generate an attractive force on the magnetic drivable artificial cilium, driving all the cilia to swing synchronously and coordinately, and the motion form is similar to the grass wave on the prairie or the coordinated fluctuation of biological cilia.

[0023] More preferably, the magnetic material is a nickel alloy or a cobalt-nickel alloy; The diameter d of the drivable artificial cilium is 2.0±0.5 μm; Beneficial effect: The use of the above magnetic material can ensure good soft magnetism and mechanical strength, and the above diameter enables the drivable artificial cilium to have sufficient rigidity to effectively stir the water flow, while maintaining flexibility to avoid breaking during swinging.

[0024] The center-to-center distance S between adjacent drivable artificial cilia satisfies S=λ·L; wherein λ is a spacing coefficient, and λ is in the range of 1.2-2.0.

[0025] Beneficial effect: This design avoids entanglement of the cilia during swinging, and ensures that the flow fields generated by the cilia can be superimposed to form an effective directional transport flow.

[0026] Preferably, the length L of the drivable artificial cilium is 50±5 μm.

[0027] Beneficial effect: This length enables the drivable artificial cilium to be effectively anchored to the filtration functional layer and protrude from the surface, thereby performing the cleaning function.

[0028] More preferably, the angle between the drivable artificial cilium and the implantation surface (i.e. the upper surface of the filtration functional layer) is 85-95°.

[0029] Beneficial effect: Vertical implantation can generate the most effective surface normal direction disturbance, which is most conducive to the detachment of pollutants.

[0030] A preparation method of a biomimetic self-cleaning water filtration core layer, comprising the following steps: A porous support layer is prepared by a non-solvent induced phase separation method, and then a nanofiber grid is formed on the surface of the porous support layer by electrospinning, after which the driveable artificial cilium is vertically implanted on the nanofiber grid by electrochemical deposition, and finally the composite substrate with the constructed nanofiber grid and driveable artificial cilium is immersed in a hydrogel precursor solution, and a biomimetic adhesive hydrogel is obtained by in-situ polymerization, thereby completing the preparation of the biomimetic self-cleaning water filtration core layer.

[0031] Preferably, the electrospinning process parameters are as follows: push pump rate: 0.8 mL / h; applied voltage: positive +15 kV (connecting the needle head), negative -5 kV (receiver); receiving distance: 15 cm; ambient temperature: 25±2℃; ambient humidity: 45±5%.

[0032] Preferably, the electrochemical deposition uses a porous anodic aluminum oxide as a template, and the porous side of the template is closely attached to the spun nanofiber layer, a special clamp is used to apply slight pressure to ensure that the contact surface has no gap.

[0033] Preferably, the electrochemical deposition uses the conductive layer on the back of the porous anodic aluminum oxide template as the cathode, uses a high-purity nickel plate as the anode, and uses a Watt-type nickel plating solution as the electrolyte; the Watt-type nickel plating solution includes the following concentrations of raw materials: nickel sulfate 240 g / L, nickel chloride 45 g / L, boric acid 30 g / L, and pH=4.0.

[0034] The application of a biomimetic self-cleaning water filtration core layer in sewage treatment is mainly suitable for scenarios where maintenance is inconvenient.

[0035] Compared with the prior art, the application has the following advantages and technical effects: The application provides a kind of bionic self-cleaning water filter core layer and preparation method thereof, by simulating the efficient filtering and self-cleaning mechanism of double-shell gill filament, a three-layer composite structure integrating the functions of "sieving-adhesion-transportation" is constructed.Compared with traditional technology, the application realizes multi-level capture of micrometer, submicron and nanometer impurities by realizing fine mechanical sieving through nanofiber grid and efficiently chemically adsorbing pollutants through bionic adhesive hydrogel.At the same time, by introducing the proportional relationship between the structure parameters (such as cilia spacing and length, filter layer thickness and cilia length, etc.), the synergistic working performance between the functional layers is optimized.The vertically drivable artificial cilium array driven by external field can generate coordinated fluctuations, transport the captured pollutants in a directional manner, realize real-time physical cleaning and functional regeneration of the filter layer, and thus fundamentally solve the clogging problem of traditional filter screens.The core layer provided by the application not only significantly improves the filtering efficiency, self-cleaning ability and structural stability through parameterized design, but also reduces the dependence on chemical cleaning agents and the need for frequent maintenance, prolongs the service life, and has significant environmental protection and energy saving advantages. BRIEF DESCRIPTION OF DRAWINGS

[0036] The drawings constituting a part of the application serve to provide a further understanding of the application, the illustrative embodiments of the application and the description thereof serve to explain the application, and do not constitute an improper limitation on the application. In the drawings: Figure 1 It is the overall schematic diagram of the filter layer obtained in Example 1; Figure 2 It is the conceptual diagram of the three-layer structure of the filter layer obtained in Example 1; Figure 3 It is the three-view and oblique view of the unit porous support layer obtained in Example 1; Figure 4 It is the schematic diagram of the three-layer structure of the filter layer obtained in Example 1; Figure 5 It is the three-view and oblique view of the unit nanofiber grid obtained in Example 1; Figure 6 It is the schematic diagram of the unit drivable artificial cilium obtained in Example 1; Figure 7 It is the structural principle diagram of the core filter layer obtained in Example 1; Figure 8 It is the working principle diagram of the core filter layer obtained in Example 1; In the drawings of the application, the numbers are as follows: 1 is a porous support layer; 2 is a filter functional layer; 3 is a drivable artificial cilium. DETAILED DESCRIPTION

[0037] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0038] In order to make the above objectives, characteristics and advantages of the present application more apparent, the present application will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0039] Unless otherwise specified, the raw materials in the embodiments of the present application are obtained by commercial channels. The polyvinylidene fluoride (PVDF) is HSV900.

[0040] Unless otherwise specified, the room temperature or normal temperature in the embodiments of the present application refers to 25±3℃.

[0041] Embodiment 1 A kind of bionic self-cleaning water filter core layer, as shown in Figures 1-6 It is a three-layer composite functional structure simulating the integrated cleaning mechanism of biological gill filament "sieving-adhesion-directional transport", including a porous support layer 1, a filtration functional layer 2 and a self-cleaning layer. Its specific structure and parameters are as follows: (1) Porous support layer 1: The material is polyvinylidene fluoride (PVDF), which is prepared by nonsolvent induced phase separation method. The average pore size is 100 μm, the porosity is 88%, and the thickness is 2.0 mm.

[0042] (2) Filtration functional layer 2: The nanofiber grid is made of chitosan and polyethyleneimine (mass ratio 7:3) electrospun, and the average diameter of the nanofiber d f =200nm, the pore size coefficient η=0.3. The average filtration pore size D=η×d f= 0.3×200=60nm. The biomimetic adhesive hydrogel is a polydopamine hydrogel, the solid content C=12wt%, the catechol group density ρ=10μmol / cm 3 . The thickness ratio coefficient k=3.0, the filtration functional layer thickness: h f =k×L=3.0×50=150μm, wherein L is the length of the drivable artificial cilium 3.

[0043] (3) Self-cleaning layer: The driveable artificial cilium 3 is a nickel nanowire with a diameter d = 2.0 μm and a length L = 50 μm. The implantation angle a = 88° (relative to the surface of the filtration functional layer). The spacing coefficient l = 1.6, and the center-to-center spacing S = l x L = 1.6 x 50 = 80 μm of adjacent cilia.

[0044] Working principle and dynamic cleaning process: As shown in Figure 7 and 8 , the biomimetic filter layer is placed in a specially designed filtration device, and an electromagnetic coil system is wrapped around the outside of the device. When working, an alternating magnetic field is applied to the coil, with a magnetic induction intensity B and a frequency f, which should respectively satisfy 50 mT < B < 80 mT and 5 Hz < f < 20 Hz. The parameters of Example 1 are 65 mT and 10 Hz. The alternating magnetic field generates an attractive force on the magnetically driveable artificial cilium 3, driving all the cilia to oscillate synchronously and coordinately, with a motion form similar to that of grass waves on a prairie or the coordinated fluctuation of biological cilia. The specific filtration and cleaning principle is as follows: 1) Primary screening and adhesion: When the water flow to be treated passes through the filter layer, micrometer-sized and larger sub-micrometer-sized particles are mechanically intercepted (screening effect) by the nanofiber grid; smaller nanometer-sized particles, heavy metal ions, and bacteria are strongly captured (adhesion effect) by the catechol groups in the polydopamine hydrogel.

[0045] 2) Dynamic transmission and removal: The array of synchronously oscillating driveable artificial cilia 3 generates a directional microflow field around it. This flow field produces two key effects: first, it "sweeps" the surface of the filtration functional layer 2, "stripping" the captured pollutants from the adhesion points; second, it continuously pushes these stripped pollutants to the edge area of the filter layer like a conveyor belt.

[0046] 3) Concentrated discharge: The concentrated pollutants at the edge can be periodically or continuously discharged from the system through a separate, low-flow discharge branch.

[0047] 4) Final effect: Thanks to the real-time self-cleaning ability of the filter layer, the core filtration layer of the present application can continuously and stably filter water at the main water outlet, fundamentally avoiding the problems of filter mesh blockage, pressure drop increase, and filtration efficiency decrease caused by dirt accumulation.

[0048] Example 2 On the basis of Example 1, the following parameters are changed: The pore size coefficient η = 0.1, and the average filtration pore size D = 20 nm.

[0049] The thickness ratio coefficient k of the filtration functional layer = 2.5, and the thickness h f = 125 μm.

[0050] The cilia spacing coefficient l = 1.2, and the center-to-center spacing S = 60 μm.

[0051] Specifically comprising the following structure: Including porous support layer 1, filtration function layer 2 and self-cleaning layer. Its specific structure and parameters are as follows: (1) Porous support layer 1: The material is polyvinylidene fluoride (PVDF), which is prepared by non-solvent induced phase separation method. Its average pore size is 100 μm, porosity is 88%, and thickness is 2.0 mm.

[0052] (2) Filtration function layer 2: The nanofiber grid is made of chitosan and polyethyleneimine (mass ratio 7:3) electrospun, and the average diameter of nanofiber d f =200nm, pore size coefficient η=0.1. The average filtration pore size D=η×d f= 0.1×200=20nm. The biomimetic adhesive hydrogel is polydopamine hydrogel, the solid content C=12wt%, the catechol group density ρ=10μmol / cm 3 . The thickness ratio coefficient k=2.5, the filtration function layer thickness: h f =k×L=2.5×50=125μm, wherein L is the length of the drivable artificial cilium 3.

[0053] (3) Self-cleaning layer: The drivable artificial cilium 3 is a nickel nanowire with a diameter of d=2.0μm and a length of L=50μm. The implantation angle α=88° (relative to the surface of the filtration function layer). The spacing coefficient λ=1.2, and the center spacing S=λ×L=1.2×50=60μm between adjacent cilia.

[0054] When working, an alternating magnetic field strength B=50mT and a frequency f=20Hz are used for driving.

[0055] Example 3 On the basis of example 1, the following parameters are changed: Pore size coefficient η=0.5, average filtration pore size D=100nm.

[0056] Filtration function layer thickness ratio coefficient k=4.0, thickness h f =200μm.

[0057] Cilium spacing coefficient λ=2.0, center spacing S=100μm.

[0058] The specific structure is as follows: (1) Porous support layer 1: The material is polyvinylidene fluoride (PVDF), which is prepared by non-solvent induced phase separation method. Its average pore size is 100 μm, porosity is 88%, and thickness is 2.0 mm.

[0059] (2) Filter function layer 2: The nanofiber mesh was electrospun from chitosan and polyethyleneimine (mass ratio 7:3), with an average nanofiber diameter d f = 200 nm and a pore size coefficient η = 0.5. The average filter pore size D = η × d f= = 0.5 × 200 = 100 nm. The biomimetic adhesive hydrogel was a polydopamine hydrogel with a solid content C = 12 wt% and a catechol group density ρ = 10 μmol / cm 3 . The thickness ratio coefficient k = 4.0, and the filter function layer thickness h f = k × L = 4.0 × 50 = 200 μm, where L is the length of the drivable artificial cilium 3.

[0060] (3) Self-cleaning layer: The drivable artificial cilium 3 was a nickel nanowire with a diameter d = 2.0 μm and a length L = 50 μm. The implantation angle α = 88° (relative to the surface of the filter function layer). The spacing coefficient λ = 2.0, and the center-to-center spacing S = λ × L = 2.0 × 50 = 100 μm of adjacent cilia.

[0061] During operation, an alternating magnetic field strength B = 80 mT and a frequency f = 5 Hz were used for driving.

[0062] Example 4 A method for preparing a biomimetic self-cleaning water filtration core layer, the structure of the biomimetic self-cleaning water filtration core layer being as in Example 1, comprising the following steps: (1) Preparation of the porous support layer 1: An 18 wt% polyvinylidene fluoride solution in N-methyl pyrrolidone was used as the casting solution, which was blade-coated on a glass plate, immersed in a 25°C deionized water coagulation bath to form a film by phase inversion, and then washed with water to remove the NMP solvent, and then hot-pressed at normal pressure and 50°C to obtain a polyvinylidene fluoride (PVDF) porous support layer with an average pore size of 100 μm, a porosity of 88%, and a thickness of 2.0 mm.

[0063] (2) Electrospinning of the nanofiber layer: Chitosan and polyethyleneimine (mass ratio 7:3) were dissolved in a volume ratio of 9:1 acetic acid aqueous solution to prepare an 8 wt% spinning solution. The porous support layer was used as the receiving substrate, and electrospinning was carried out under the following conditions: positive voltage +15 kV, negative voltage -5 kV, receiving distance 15 cm, and pushing rate 0.8 mL / h, for 30 minutes, to form a nanofiber mesh with an average diameter of 200 nm on the surface thereof.

[0064] (3) Vertical implantation of the drivable artificial cilium 3: A porous anodic aluminum oxide (AAO) template with a pore diameter of 2.0 μm and a pore depth of 50 μm was tightly attached to the surface of the nanofiber layer. The template was used as a cathode, and nickel nanowire arrays were vertically implanted in a Watts-type nickel plating solution at a current density of -10 mA / cm 2 for 25 minutes. Subsequently, the AAO template was dissolved to obtain the nickel nanowire arrays vertically implanted, with a diameter d = 2.0 μm, a length L = 50 μm, and a center-to-center spacing S = 80 μm.

[0065] (4) In-situ polymerization of the biomimetic adhesive hydrogel: The composite substrate with the cilia array was immersed in a dopamine Tris-HCl solution at 2 mg / mL and pH = 8.5, and oscillated at 80 rpm for 12 hours at 25°C. After being taken out, washed, and dried at 60°C, a composite filtration functional layer with a polydopamine hydrogel filled was obtained, with a solid content C of 12% and a catechol group density p of 10 μmol / cm 3 .

[0066] Example 5 A method for preparing a biomimetic self-cleaning water filtration core layer, the structure of the core layer being as described in Example 2, includes the following steps: (1) Preparation of the porous support layer 1: A polyvinylidene fluoride N-methyl pyrrolidone solution with a concentration of 18 wt% was used as a casting solution, which was blade-coated on a glass plate, immersed in a deionized water coagulation bath at 25°C to be phase-inverted into a film, and then washed with water to remove the NMP solvent, and then hot-pressed at normal pressure and 50°C to obtain a PVDF porous support layer with an average pore diameter of 100 μm, a porosity of 88%, and a thickness of 2.0 mm.

[0067] (2) Electrospinning of the nanofiber layer: Chitosan and polyethyleneimine (mass ratio 7:3) were dissolved in an acetic acid aqueous solution with a volume ratio of 9:1 to prepare a 8 wt% spinning solution. The porous support layer was used as a receiving substrate, and the nanofiber grid with an average diameter of 200 nm was formed on the surface of the porous support layer by electrospinning under the following conditions: positive electrode voltage +15 kV, negative electrode voltage -5 kV, receiving distance 15 cm, and solution advancing rate 0.8 mL / h for 20 minutes.

[0068] (3) Vertical implantation of the drivable artificial cilia 3: A porous anodic aluminum oxide (AAO) template with a pore diameter of 2.0 μm and a pore depth of 50 μm was tightly attached to the surface of the nanofiber layer. The template was used as a cathode, and nickel nanowire arrays were vertically implanted in a Watts-type nickel plating solution at a current density of -10 mA / cm 2 for 18 minutes. Subsequently, the AAO template was dissolved to obtain the nickel nanowire arrays vertically implanted, with a diameter d = 2.0 μm, a length L = 50 μm, and a center-to-center spacing S = 60 μm.

[0069] (4) In-situ polymerization of the bio-inspired adhesive hydrogel: The composite substrate with the cilia array was immersed in a 2 mg / mL dopamine Tris-HCl solution at pH = 8.5 and reacted at 25 °C under 80 rpm oscillation for 10 hours. After being taken out, washed and dried at 60 °C, a composite filtration functional layer with polydopamine hydrogel filled was obtained, with a solid content C of 12% and a catechol group density p of 10 μmol / cm 3 .

[0070] Example 6 A method for preparing a bio-inspired self-cleaning water filtration core layer, the structure of the core layer being as described in Example 3, comprising the following steps: (1) Preparation of the porous support layer 1: A polyvinylidene fluoride N-methyl pyrrolidone solution with a concentration of 18 wt% was used as a casting solution, which was blade-coated on a glass plate, immersed in a 25 °C deionized water coagulation bath to be phase-inverted into a film, and then washed with water to remove the NMP solvent, and then hot-pressed at normal pressure and 50 °C to obtain a PVDF porous support layer with an average pore size of 100 μm, a porosity of 88%, and a thickness of 2.0 mm.

[0071] (2) Electrospinning of the nanofiber layer: Chitosan and polyethyleneimine (mass ratio 7:3) were dissolved in a volume ratio of 9:1 acetic acid aqueous solution to prepare a 8 wt% spinning solution. The porous support layer was used as a receiving substrate, and electrospinning was carried out under the conditions of positive voltage +15 kV, negative voltage -5 kV, receiving distance 15 cm, and solution advancing rate 0.8 mL / h for 40 minutes to form a nanofiber grid with an average diameter of 200 nm on the surface of the porous support layer.

[0072] (3) Vertical implantation of the drivable artificial cilium 3: A porous anodic aluminum oxide (AAO) template with a pore size of 2.0 μm and a pore depth of 50 μm was tightly attached to the surface of the nanofiber layer. The template was used as a cathode, and nickel nanowire arrays were electrodeposited in a 50 °C Watt-type nickel plating solution at a current density of -10 mA / cm 2 for 30 minutes. Subsequently, the AAO template was dissolved to obtain vertically implanted nickel nanowire arrays with a diameter d = 2.0 μm, a length L = 50 μm, and a center-to-center distance S = 100 μm between adjacent cilia.

[0073] (4) In-situ polymerization of the bio-inspired adhesive hydrogel: The composite substrate with cilia array was immersed in a 2 mg / mL dopamine Tris-HCl solution with pH = 8.5, and reacted at 25°C under the condition of 80 rpm oscillation for 14 hours. After being taken out, washed and dried at 60°C, a composite filtration functional layer with polydopamine hydrogel filling was obtained, with solid content C of 12% and catechol group density p of 10 pmol / cm2. 3 .

[0074] Comparative Example 1 The difference from Example 1 is only that no artificial cilia 3 is implanted. The rest of the materials and structures are the same as those of Example 1.

[0075] Comparative Example 2 The difference from Example 1 is only that step (4) in-situ polymerization of biomimetic adhesive hydrogel is omitted. That is, the filtration functional layer only contains a nanofiber grid without polydopamine hydrogel. The rest of the materials and structures are the same as those of Example 1.

[0076] Comparative Example 3 The difference from Example 1 is only that step (2) electrospinning of the nanofiber layer is omitted. That is, the filtration functional layer is only composed of polydopamine hydrogel polymerized directly on the porous support layer, lacking a nanofiber grid as a support. The rest of the materials and structures are the same as those of Example 1.

[0077] Comparative Example 4 The difference from Example 1 is that the structure of the biomimetic self-cleaning water filtration core layer is changed, specifically: first, a nanofiber grid is prepared on the porous support layer, then a nickel nanowire array is directly electrodeposited and grown on the nanofiber grid to form a separate cilia layer, and finally a polydopamine hydrogel layer is in-situ polymerized on the cilia layer. That is, the structure is a sequential layering structure of “porous support layer / nanofiber layer / cilia layer / hydrogel layer”, rather than an integrated structure with cilia vertically implanted into the filtration functional layer.

[0078] Technical effects: The filtration core layers obtained in Examples 1-3 and Comparative Examples 1-4 were tested for performance. The test conditions were: treating simulated wastewater containing 200 mg / L micron-sized diatomite, 50 mg / L nano-sized carbon black particles and 10 mg / L Cu² + , constant flow filtration (10 mL / min), and starting the alternating magnetic field (Example 1 parameters: 65 mT, 10 Hz) cleaning for 2 minutes every 30 minutes of operation. The expected effects are shown in Table 1: Table 1 As can be seen from Table 1: (1) The necessity of dynamic self-cleaning: Embodiments 1-3 of the present application realize excellent long-term flux retention and efficient cleaning recovery by virtue of the directional micro-flow field driven by artificial cilia. In contrast, Comparative Example 1 lacks this mechanism, and the rapid accumulation of pollutants leads to serious blockage, indicating that dynamic self-cleaning is the key to solving the problem of filter layer blockage.

[0079] (2) The necessity of "sieving-adhesion" synergy: Embodiments 1-3 achieve efficient and comprehensive removal of pollutants. Comparative Example 2 lacks adhesive hydrogel, and the removal rate of small molecules and ions is extremely low; Comparative Example 3 lacks a nanofiber sieving skeleton, and the interception rate of large particles is low and the structure is unstable, indicating that both functions are indispensable.

[0080] (3) The superiority of the "vertical implantation" integrated structure: The integrated structure of Embodiments 1-3 enables cilia oscillation to directly act on the pollutant capture site, resulting in high cleaning efficiency. However, the layered structure of Comparative Example 4 leads to easy retention of pollutants between layers, and the cleaning flow field cannot effectively act on the interior of the hydrogel, resulting in a significantly lower flux recovery rate, demonstrating the advantages of the core structural design of the present application.

[0081] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A biomimetic self-cleaning water filter core layer, characterized in that, It includes a porous support layer, a filter functional layer, and a self-cleaning layer; The filter functional layer is composited on the porous support layer; The filtration functional layer includes an interwoven nanofiber mesh and a biomimetic adhesive hydrogel filled in the nanofiber mesh; The self-cleaning layer includes a driveable artificial cilia array, which penetrates vertically through the filter functional layer.

2. The biomimetic self-cleaning water filter core layer according to claim 1, characterized in that, The porous support layer is a porous membrane with a three-dimensional interconnected pore structure prepared from polyvinylidene fluoride; and / or, The porous support layer has an average pore diameter of 100±20μm, a porosity of 85-90%, and a thickness of 2.0mm.

3. The biomimetic self-cleaning water filter core layer according to claim 1, characterized in that, The pore size D of the filtration functional layer satisfies D=η·d f ; Where η is 0.1-0.5; d f Let d be the average diameter of the nanofibers in the nanofiber mesh. f 200±50nm; and / or, The thickness h of the filter functional layer f Satisfy h f =k·L; Where k is between 1.0 and 2.5; L is the length of the driveable artificial cilia.

4. The biomimetic self-cleaning water filter core layer according to claim 1, characterized in that, The biomimetic adhesion hydrogel is a polymer hydrogel rich in catechol groups.

5. The biomimetic self-cleaning water filter core layer according to claim 1, characterized in that, The driveable artificial cilia are made of magnetic material and are driven to swing synchronously by applying an alternating magnetic field. The alternating magnetic field has an induced intensity of 50-80 mT and a frequency of 5-20 Hz.

6. The biomimetic self-cleaning water filter core layer according to claim 1, characterized in that, The diameter d of the dable artificial cilia is 2.0±0.5μm, and the center-to-center distance S between adjacent dable artificial cilia satisfies S=λ·L; Where λ is 1.2-2.

0.

7. A biomimetic self-cleaning water filter core layer according to claim 3 or 6, characterized in that, The length L of the driveable artificial cilia is 50±5μm.

8. A method for preparing a biomimetic self-cleaning water filter core layer as described in any one of claims 1-7, characterized in that, Includes the following steps: A porous support layer was prepared using a non-solvent phase separation method. Then, a nanofiber mesh was formed on the surface of the porous support layer by electrospinning. The drivable artificial cilia were then vertically implanted onto the nanofiber mesh by electrochemical deposition. Finally, the composite substrate with the nanofiber mesh and drivable artificial cilia was immersed in a hydrogel precursor solution and polymerized in situ to obtain a biomimetic adhesive hydrogel, thus completing the preparation of the biomimetic self-cleaning water filter core layer.

9. The method for preparing a biomimetic self-cleaning water filter core layer according to claim 8, characterized in that, The electrospinning process parameters are as follows: feed pump speed: 0.8 mL / h; applied voltage: positive electrode +15 kV (needle head), negative electrode -5 kV (receiver); receiving distance: 15 cm; ambient temperature: 25 ± 2 ℃; ambient humidity: 45 ± 5%.

10. The application of a biomimetic self-cleaning water filter core layer as described in any one of claims 1-7 in wastewater treatment.

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