pH-photothermal dual-responsive self-healing separation membrane, preparation method and application thereof

Abstract

This invention relates to a pH-photothermal dual-response self-healing separation membrane, its preparation method, and its application. The pH-photothermal dual-response self-healing separation membrane comprises, from bottom to top, a support layer, a pH-photothermal dual-response self-healing functional layer, and a superhydrophobic separation functional layer. The pH-photothermal dual-response self-healing functional layer is prepared using a rod-shaped or fibrous silicate mineral as a carrier, through sequential carrier activation, loading of photothermal materials, loading of a repair agent, and pH-responsive gating encapsulation of a polymer material. This invention ensures the membrane's mechanical and separation properties while achieving synergistic repair of both physical and chemical corrosion damage.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation technology, specifically relating to pH-photothermal dual-response self-healing separation membrane, its preparation method, and its application. Background Technology

[0002] Membrane separation technology has been widely used in oily wastewater treatment, dyeing and printing wastewater purification, and seawater desalination pretreatment. During long-term operation, the membrane surface will inevitably suffer physical damage (such as scratches, wear, and tears) and chemical damage (such as acid and alkali corrosion and oxidative degradation), which will lead to a decrease in membrane selectivity, an abnormal increase in flux, and a significant decrease in separation efficiency, ultimately causing premature failure of the membrane module and a significant increase in operating costs.

[0003] Existing self-healing membrane technologies mainly include microcapsule repair, photocatalytic self-cleaning, and reversible covalent bond or supramolecular interaction self-healing. Microcapsule-type self-healing membranes suffer from problems such as large capsule size, easy pore blockage, and limited repair cycles; photocatalytic technology focuses on pollutant degradation and cannot repair structural damage; single thermal response or pH response technologies are difficult to address both physical damage and chemical corrosion simultaneously, and most require offline processing, making in-situ repair in industrial settings impossible. Among these, pH-responsive membranes mostly achieve response and repair based on supramolecular interactions (hydrogen bonds, electrostatic interactions), while thermal response membranes mostly rely on the breaking and recombination of reversible covalent bonds (imine bonds, disulfide bonds, etc.). Neither of these approaches can simultaneously achieve remote triggering, precise controlled release, and long-term stability. Furthermore, although self-healing materials based on dual-response mechanisms have emerged in recent years, such as the dual-response anti-corrosion filler disclosed in Chinese patent CN 202310170559.8, which uses reduced graphene oxide-silica (rGO-SiO2) as a carrier, it has the following problems: 1) rGO-SiO2 is a synthetic nanomaterial, which is costly, complex to prepare on a large scale, and has a wide particle size distribution that easily clogs membrane pores; 2) The anti-corrosion filler of this technology is added to the coating and does not involve a three-layer composite membrane structure, so it cannot simultaneously guarantee the synergy of mechanical strength, repair function and separation performance; the above problems prevent it from being applied in the field of separation membranes.

[0004] Therefore, developing a separation membrane that combines pH and photothermal dual response, can precisely control release and self-repair, can achieve remote non-contact in-situ repair while not easily clogging the membrane pores, and has good mechanical strength and separation performance has significant engineering value. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects in the prior art and provide a pH-photothermal dual-response self-healing separation membrane, its preparation method and application. While ensuring the mechanical and separation performance of the membrane, it can also achieve synergistic repair of physical damage and chemical corrosion damage, and realize in-situ self-healing of the membrane. This not only improves the effect of physical damage repair and chemical corrosion repair of the membrane, but also eliminates the need to disassemble the membrane module, thus significantly reducing operation and maintenance costs.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A pH-photothermal dual-response self-healing separation membrane includes a support layer, a pH-photothermal dual-response self-healing functional layer and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0008] The pH-photothermal dual-response self-healing functional layer is made of pH-photothermal dual-response self-healing composite material;

[0009] The pH-photothermal dual-response self-healing composite material is prepared by sequentially activating the carrier, loading the photothermal material, loading the repair agent, and encapsulating the polymer material under pH-responsive gating using rod-shaped or fibrous silicate minerals as a carrier.

[0010] As a further technical solution, the support layer includes a polytetrafluoroethylene support layer, a polyvinylidene fluoride support layer, a polyester nonwoven fabric support layer, a polypropylene nonwoven fabric support layer, a polyamide support layer, or a nylon fabric support layer.

[0011] As a further technical solution, the thickness of the support layer is 100-300 μm.

[0012] As a further technical solution, the thickness of the pH-photothermal dual-response self-healing functional layer is 3-20 μm.

[0013] As a further technical solution, the thickness of the superhydrophobic separation functional layer is 50–200 μm.

[0014] As a further technical solution, the water contact angle of the superhydrophobic separation functional layer is ≥150°. The water contact angle threshold of this invention is set based on the Cassie-Baxter model, which can ensure the formation of a stable gas film during oil-water separation, achieving efficient antifouling and hydrophobic separation.

[0015] As a further technical solution, the preparation method of the pH-photothermal dual-response self-healing composite material includes the following steps:

[0016] (1) Activation of the carrier: The rod-shaped or fibrous silicate minerals are calcined at 300-500℃ and activated. After cooling, they are refluxed with 3-8 mol / L hydrochloric acid under stirring. After centrifugation, the solid is collected, washed until neutral, vacuum dried, ground and sieved to obtain the activated carrier.

[0017] (2) Photothermal material loading: The activated carrier is dispersed in water, and then the photothermal material or photothermal material precursor is added. The pH value is adjusted to 9-11, and the reaction is heated for 4-24 hours to obtain a composite material loaded with photothermal material.

[0018] (3) Loading of repair agent: The composite material loaded with photothermal material is dispersed in ethanol, hydrophobic silane and repair agent are added, and then ultrasonic treatment is performed for 10 to 30 minutes (purpose: to promote the repair agent to enter the deep pores of the carrier). Then, it is stirred and adsorbed at room temperature (20 to 30°C) for 12 to 24 hours, and then centrifuged and dried to obtain the composite material loaded with photothermal material-repair agent.

[0019] (4) pH-responsive gated encapsulation: The composite material loaded with photothermal material-repair agent is dispersed in acetate buffer, then hydrophilic polymer is added, crosslinking agent solution is added dropwise, and crosslinking reaction is carried out at 30-50℃. The reaction time is controlled so that the degree of crosslinking is 50-80%. After centrifugation and drying, pH-photothermal dual-responsive self-repairing composite material is obtained.

[0020] As a further technical solution, the carrier activation includes: first calcination activation, and then acid activation.

[0021] As a further technical solution, the silicate mineral includes any one of attapulgite, sepiolite, and halloysite.

[0022] As a further technical solution, the photothermal material precursor includes any one of soluble cerium salt and graphene oxide.

[0023] As a further technical solution, the photothermal material includes nano-cerium oxide, reduced graphene oxide, carbon nanotubes, and MXene (Ti3C2T). x T x It is any one of the surface terminal groups -O, -OH or -F, x=1 to 3.

[0024] As a further technical solution, the soluble cerium salt includes any one of cerium nitrate and cerium chloride.

[0025] As a further technical solution, in the composite material loaded with photothermal material, the loading amount of photothermal material is 5-15 wt%, preferably 8-12 wt% (if a photothermal material precursor is used, the mass after the precursor is completely converted into the corresponding photothermal material is calculated).

[0026] As a further technical solution, the repair agent includes one or more of 2-mercaptobenzothiazole, benzotriazole, and 2-mercaptobenzimidazole.

[0027] As a further technical solution, the hydrophilic polymer includes one or more of chitosan, carboxymethyl chitosan, sodium alginate, and gelatin.

[0028] As a further technical solution, the concentration of the crosslinking agent solution is 20-30 wt%.

[0029] As a further technical solution, the hydrophobic silane includes one or more of perfluorodecyltrimethoxysilane, perfluorooctyltrimethoxysilane, and heptadecafluorodecyltrimethoxysilane.

[0030] As a further technical solution, the superhydrophobic separation functional layer is prepared by hydrophobic modified silicate minerals and polymers through a non-solvent-induced phase separation method.

[0031] As a further technical solution, the mass ratio of the hydrophobic modified silicate mineral to the polymer is 1:4 to 6.

[0032] As a further technical solution, the hydrophobically modified silicate mineral includes any one of hydrophobically modified attapulgite and hydrophobically modified sepiolite.

[0033] As a further technical solution, the polymer includes fluoropolymers or polyethersulfone.

[0034] As a further technical solution, the fluoropolymer includes polyvinylidene fluoride.

[0035] The preparation method of the pH-photothermal dual-response self-healing separation membrane includes the following steps:

[0036] Step 1: Prepare pH-photothermal dual-response self-healing composite material;

[0037] Step 2: Preparation of pH-photothermal dual-response self-healing functional layer: The pH-photothermal dual-response self-healing composite material and dispersant are added to the resin material and stirred and dispersed evenly at a temperature of ≤40℃. Then, it is coated on the surface of the support layer, and the wet film thickness is controlled so that the dry film thickness is 3~20μm. After curing, the pH-photothermal dual-response self-healing functional layer is formed.

[0038] Step 3: Preparation of superhydrophobic separation functional layer: Dissolve or disperse hydrophobic modified silicate minerals and polymers in a solvent, then add a pore-forming agent, stir evenly, and form a film by non-solvent-induced phase separation method. Then, control the coagulation bath temperature to 10-30℃ and the pH value of the coagulation bath to 6.5-7.5 for coagulation bath solidification to form a superhydrophobic separation functional layer, and obtain a pH-photothermal dual-response self-healing separation membrane.

[0039] As a further technical solution, the resin material includes any one of waterborne polyurethane, waterborne acrylic resin, and waterborne epoxy resin.

[0040] As a further technical solution, the dispersant includes any one of BYK-190, BYK-163, and DISPERBYK-110.

[0041] As a further technical solution, the solvent includes one or more of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0042] As a further technical solution, the porogen includes one or two of polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG), and the concentration of the porogen is 8-15 wt%.

[0043] Application of the pH-photothermal dual-response self-healing separation membrane in oily wastewater, dyeing and printing wastewater, or industrial mixed wastewater containing oil and dye.

[0044] The working mechanism of this invention:

[0045] The principle of controlled release of the "chitosan or its derivative-glutaraldehyde" system of this invention based on the "cross-linked network swelling-diffusion control mechanism" is as follows:

[0046] 1) Acid-triggered mechanism (pH 3-5): The pH-responsive gating structure of this invention is mainly achieved through the Schiff base dynamic covalent network of chitosan polymers. Under weakly acidic conditions (pH 4.0-6.0), this mechanism is driven by both physical swelling and chemical dynamic equilibrium: on the one hand, the free amino groups (-NH2) remaining on the chitosan molecular chain undergo protonation to generate protonated amino groups (-NH3). + The electrostatic repulsion causes significant physical swelling of the cross-linked network. On the other hand, the Schiff base bond (-C=N-) undergoes reversible hydrolysis under acidic conditions, but the bond strength decreases, which greatly improves the flexibility and permeability of the molecular chain, thereby synergistically inducing the "opening" of the encapsulation channel and realizing the precise release of the repair agent.

[0047] At this point, the cross-linked network undergoes partial reversible dissociation, and the increased network pore size enables controlled release, allowing the internally loaded small molecule repair agent to rapidly diffuse and release through the expanded network gaps, thereby repairing acid corrosion damage.

[0048] 2) Alkaline triggering mechanism (pH 10-12): In a strongly alkaline environment, high concentrations of OH- - With the -NH3 on the molecular chain of chitosan or its derivatives + Deprotonation occurs, and OH... - Competition disrupts the intramolecular and intermolecular hydrogen bond network, leading to a decrease in the compactness of the polymer matrix, conformational changes, and relaxation. The "deprotonation" mechanism here differs from the "deprotonation contraction" mechanism under neutral conditions: under neutral conditions, deprotonation strengthens hydrogen bonds, leading to compaction; while under strongly alkaline conditions, it is the OH-... - Excessive disruption of hydrogen bonds leads to relaxation swelling. This matrix relaxation effect reduces diffusion resistance, and combined with the microcrack stress generated by localized corrosion, it increases the permeability of the encapsulation layer, thereby releasing the repair agent.

[0049] 3) pH-responsive gated encapsulation: The composite material loaded with photothermal material and repair agent is dispersed in an acetate buffer solution with a pH of 4.0–4.8. A hydrophilic polymer is added, and a crosslinking agent solution is added dropwise. The crosslinking reaction is carried out at 30–50°C. This pH condition is lower than the pKa of chitosan or its derivatives (approximately 6.3), causing partial protonation and swelling of the chitosan or its derivative molecular chains. The crosslinking reaction occurs in the swollen state. When the ambient pH returns to neutral, the intermolecular hydrogen bonding of the deprotonated chitosan or its derivatives is enhanced, and the crosslinking network becomes denser, forming a "closed" state. It should be noted that for different hydrophilic polymers, due to differences in amino content, the crosslinking density corresponding to the same degree of crosslinking (based on amino consumption rate) varies. However, the key to this invention lies in forming a pH-responsive gated structure through a cross-linking reaction. Although the amino content of different hydrophilic polymers varies, resulting in different cross-linking densities corresponding to the same degree of cross-linking, as long as the degree of cross-linking is controlled within the range of 50% to 80%, the 'acid swelling opening and neutral density closing' response characteristics can be achieved.

[0050] 4) Photothermal Triggering Mechanism: This invention uses broad-spectrum absorbing materials such as CeO2, rGO, CNT, and MXene for photothermal triggering. The photothermal triggering mechanism is as follows: the photothermal materials loaded on the carrier surface generate local high temperatures under 808nm near-infrared laser irradiation: CeO2 generates heat through localized surface plasmon resonance (LSPR) mediated by oxygen vacancy defect states and interband transitions; MXene generates heat through interband transitions and vibrations of surface terminal groups; rGO and CNT generate heat through photothermal electronic transitions in a π-electron conjugated system. When the temperature rises above 55℃, the thermal motion of polymer chain segments in the chitosan or carboxymethyl chitosan and glutaraldehyde crosslinking network intensifies, hydrogen bonding weakens, and the network pore size temporarily increases; simultaneously, the thermal expansion effect generates local stress, which synergistically promotes the increase of the permeability of the encapsulation layer, allowing the internally loaded repair agent to be released and migrate to the damage site, achieving photothermal triggering in-situ repair; this process mainly involves physical thermal expansion and hydrogen bond weakening. After the temperature recovers, the crosslinking network can be re-densified, ensuring the long-term storage of the repair agent.

[0051] 5) Thickness: The thickness of the superhydrophobic separation functional layer in this invention is 50–200 μm. When the thickness is less than 50 μm, the mechanical strength of the superhydrophobic separation functional layer is relatively insufficient, making it easier to be penetrated by deeper scratches. When the thickness of the superhydrophobic separation functional layer exceeds 200 μm, the membrane flux decreases significantly, and the time for heat transfer to the damage site during photothermal response is prolonged, which may affect the repair efficiency. Therefore, the preferred thickness range of this invention is 50–200 μm, within which a good balance between separation performance and repair performance can be achieved.

[0052] 6) Simple Repair Triggering Methods in Industrial Applications: This invention offers two repair triggering methods: pH response and photothermal response. Photothermal response triggering typically utilizes 808nm near-infrared laser irradiation, allowing the local temperature to rapidly reach the response range of 55–70°C after irradiation. Because the polymer cross-linked network of the encapsulation layer undergoes thermal expansion and chain segment relaxation upon temperature increase, the pore size increases, thereby releasing the repair agent. Therefore, any heat source capable of raising the temperature of the damaged area above the response threshold can be used to trigger the photothermal self-repair of this invention.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] 1. The separation membrane of the present invention has a three-layer structure with distinct functions: a support layer provides mechanical strength, a pH-photothermal dual-response self-healing layer stores and controls the release of repair agents to achieve self-healing of the separation membrane, and a hydrophobic separation functional layer ensures the separation performance of the membrane. The three layers each perform their respective functions, ensuring the synergy of mechanical strength, repair function and separation performance, so that the separation membrane of the present invention can treat oily wastewater, dyeing wastewater and complex industrial oily dyeing wastewater.

[0055] 2. The pH-photothermal dual-response self-healing composite material of this invention uses activated rod-shaped or fibrous silicate minerals as a carrier, and performs photothermal material loading, repair agent loading, and pH-gated encapsulation, thereby achieving photothermal-pH dual response. This allows the separation membrane to achieve in-situ self-healing during wastewater treatment. Compared with the separation membranes that require shutdown for repair in traditional technologies, it eliminates the need to disassemble the membrane module, significantly reducing operation and maintenance costs; among them, such as Figure 2 As shown, rod-shaped or fibrous silicate minerals, after activation, possess abundant micropores and mesopores. These pores serve as a reservoir for repair agents and facilitate the migration of repair agents to damage sites driven by concentration gradients. Compared to the "dead-end pore" structure of spherical particles (such as mesoporous silica), the continuous transport channels employed in this invention interconnect the pores of fibrous minerals, shortening the repair agent path and achieving faster response repair. Furthermore, the hydrophilic polymer cross-linked layer used in the gated encapsulation provides a tight seal under normal operating conditions, preventing repair agent leakage. The repair agent is released only under damage-triggered conditions, enabling multiple cycles of repair and improving the repair effect.

[0056] 3. This invention uses photothermal materials such as CeO2, rGO, and CNT for photothermal triggering. The photothermal triggering mechanism is as follows: the photothermal materials loaded on the carrier surface generate local high temperatures under 808nm near-infrared laser irradiation: CeO2 generates heat through band gap transitions and lattice vibrations; MXene generates heat through surface plasmon resonance and electronic transitions; rGO and CNT generate heat through photothermal electronic transitions in a π-electron conjugated system. When the temperature rises above 55℃, the thermal motion of polymer chain segments in the chitosan or carboxymethyl chitosan and glutaraldehyde crosslinking network intensifies, hydrogen bonding weakens, and the network pore size temporarily increases. At the same time, the thermal expansion effect generates local stress, which synergistically promotes the increase of the permeability of the encapsulation layer, allowing the internally loaded repair agent to be released and migrate to the damage site, realizing photothermal triggering in-situ repair. This process involves physical thermal expansion and hydrogen bond weakening. After the temperature recovers, the crosslinking network can be re-densified, ensuring the long-term storage of the repair agent.

[0057] 4. When preparing the pH-photothermal dual-responsive self-healing functional layer, the ratio of resin material (such as waterborne polyurethane) to the pH-photothermal dual-responsive self-healing composite material should be controlled. If the resin content is too high, the concentration of the pH-photothermal dual-responsive self-healing composite material will be too low. When its concentration is below 3 wt%, the resin material may penetrate into the carrier nanopores and block the release channels of the repair agent, thus affecting the repair efficiency. If the concentration of the pH-photothermal dual-responsive self-healing composite material is too high, such as greater than 10 wt%, it may lead to a decrease in the cohesion of the pH-photothermal dual-responsive self-healing functional layer, thus making it prone to cracking. The preferred concentration of the pH-photothermal dual-responsive self-healing composite material in this invention is 3-8 wt%. Within this range, the resin material can achieve good coating of the carrier without blocking the pore openings.

[0058] In summary, the separation membrane prepared by this invention can achieve synergistic repair through both pH and photothermal responses, and can simultaneously repair physical damage and chemical corrosion, greatly improving the membrane's repair effect. Furthermore, this invention uses natural clay minerals instead of expensive synthetic materials, significantly reducing costs and making it more suitable for industrial-scale production. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the structure of the separation membrane prepared in one embodiment of the present invention;

[0060] exist Figure 1 The structure consists of: 1. a superhydrophobic separation functional layer; 2. a pH-photothermal dual-response self-healing functional layer; and 3. a support layer.

[0061] Figure 2 This is a microscopic schematic diagram of the pH-photothermal dual-response self-healing composite material prepared in one embodiment of the present invention.

[0062] Figure 3 This is an infrared thermal image of the separation membrane during the photothermal repair process in Example 1. Detailed Implementation

[0063] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] 1. Attapulgite (rod-shaped crystals): specific surface area 210–275 m² 2 / g, aspect ratio 10:1, purity ≥95%, Jiangsu Jiuchuan Nanomaterials Technology Co., Ltd.

[0065] 2. Chitosan (degree of deacetylation DD92%, 15kDa): Zhejiang Jinke Pharmaceutical Co., Ltd.

[0066] Chitosan (degree of deacetylation DD85%, 25kDa): Shandong Aokang Biotechnology Co., Ltd.

[0067] Chitosan (degree of deacetylation DD90%, 10kDa): Shanghai Yuanye Biotechnology Co., Ltd.

[0068] Carboxymethyl chitosan (degree of deacetylation DD82%, 20kDa): Zhejiang Jinke Pharmaceutical Co., Ltd.

[0069] 3. Waterborne polyurethane: Solid content 30%, viscosity 1000~3000mPa·s; Wanhua Chemical Group Co., Ltd.

[0070] 4. Polymer PVDF: Solef 5130, molecular weight 50-60kDa; Solvay specialty polymer.

[0071] 5. Hydrophobically modified silicate minerals: Perfluorodecyltrimethoxysilane modified attapulgite, contact angle ≥140°; Jiangsu Jiuchuan Nanomaterials Technology Co., Ltd.

[0072] 6. Sepiolite (fibrous aggregate): specific surface area 180–198 m² 2 / g, fiber aspect ratio 8:1; Hunan Chaopai Technology Co., Ltd.

[0073] 7. Waterborne acrylic resin: 40% solids content, glass transition temperature -10℃; BASF (China) Co., Ltd.

[0074] 8. Polymer PES: BASF E6020, molecular weight 55kDa; BASF (China) Co., Ltd.

[0075] 9. Carboxylated multi-walled carbon nanotubes (MWCNT-COOH, length 0.5~2μm, diameter 10~20nm, carboxyl content 2.0wt%): Suzhou CarbonFeng Graphene Technology Co., Ltd.

[0076] 10. Graphene oxide (GO, monolayer ratio > 90%, thickness 0.8-1.2nm): Changzhou Sixth Element Materials Technology Co., Ltd.

[0077] 11. Reduced graphene oxide (rGO): Carbon content ≥95%, specific surface area 300-500 m² 2 / g; Changzhou Sixth Element Materials Technology Co., Ltd.

[0078] 12. MXene (Ti3C2T) x Tx is -O, -OH, -F, x=1~3): few-layer Ti3C2T x Nanosheets, Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0079] 13. Unless otherwise specified, all raw materials used in this invention are commercially available.

[0080] 14. Method for determining the degree of crosslinking: The degree of crosslinking in this invention refers to the percentage of free amino groups (-NH2) in the molecular chain of a hydrophilic polymer consumed after reaction with a crosslinking agent. It is determined using the ninhydrin colorimetric method: Weigh 10 mg of each sample before and after crosslinking, add 2 mL of ninhydrin colorimetric solution (0.1% ninhydrin ethanol solution), heat in a boiling water bath for 20 min, cool, and measure the absorbance at 570 nm. Three parallel samples are set up for each test, with an experimental error ≤ ±2%.

[0081] .

[0082] Example 1

[0083] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer 3, a pH-photothermal dual-responsive self-healing functional layer 2, and a superhydrophobic separation functional layer 1 arranged sequentially from bottom to top.

[0084] Its preparation method includes the following steps:

[0085] Step 1: Preparation of pH-photothermal dual-response self-healing composite material

[0086] Step 1-1, Mineral Activation: Roast the rod-shaped or fibrous silicate mineral (attapulgite, rod-shaped crystals) at 300℃ for 2 hours at a rate of 5℃ / min. After cooling, add 6mol / L hydrochloric acid at a solid-liquid ratio of 1g:10mL under stirring and reflux at 80℃ for 4 hours. Centrifuge, collect the solid, wash until neutral, vacuum dry at 80℃, grind, and pass through a 200-mesh sieve to obtain the activated carrier (specific surface area 210m²). 2 / g).

[0087] Steps 1-2: Photothermal material loading: Disperse 0.5g of the activated carrier in 50mL of deionized water, add 0.155g of the photothermal material precursor Ce(NO3)3·6H2O, adjust the pH to 10, and perform a hydrothermal reaction at 120℃ for 12h. Wash and dry to obtain the composite material ATP@CeO2 loaded with photothermal material (loaded at 12.3wt% based on photothermal material CeO2, with a particle size of 8-15nm).

[0088] Steps 1-3: Loading the repair agent: 1.0 g of the composite material ATP@CeO2 loaded with the photothermal material was dispersed in 50 mL of ethanol. 0.25 g of hydrophobic silane (perfluorodecyltrimethoxysilane) and 0.15 g of the repair agent 2-mercaptobenzothiazole were added. The mixture was ultrasonically treated for 15 min, then stirred and adsorbed at 20℃~30℃ for 12 h. After centrifugation and drying, the composite material loaded with the photothermal material and repair agent was obtained. During this process, the hydrophobic silane simultaneously modifies the surface of the carrier, enhancing the hydrophobic adsorption of the repair agent and improving the compatibility of the composite material with the subsequent organic resin matrix.

[0089] Steps 1-4, pH-responsive gated encapsulation: Disperse 0.5g of the composite material loaded with photothermal material-repair agent in 50mL of acetate buffer solution with pH 4.5, add 0.2g of chitosan (DD 92%, 15kDa), add 0.5mL of crosslinking agent solution (25wt% glutaraldehyde aqueous solution), and crosslink at 40℃ for 4h (the degree of crosslinking was determined to be 65% according to the ninhydrin colorimetric method). Wash and dry to obtain pH-photothermal dual-responsive self-healing composite material;

[0090] Step 2: Preparation of pH-photothermal dual-responsive self-healing functional layer: The composite material was dispersed in waterborne polyurethane at a concentration of 5 wt%, and 0.5 wt% dispersant BYK-190 was added. The dispersion temperature was controlled at 35℃ and the mixture was stirred until uniformly dispersed to obtain the self-healing material. Then, the self-healing material was coated onto the surface of a 200 μm PTFE support layer using a doctor blade. The wet film was 50 μm thick and cured at 60℃ for 2 hours to form a pH-photothermal dual-responsive self-healing functional layer (dry film thickness approximately 12 μm).

[0091] Step 3: Preparation of the superhydrophobic separation functional layer: Hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and PVDF were compounded at a mass ratio of 1:5. The hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and polymer PVDF were dissolved in N-methylpyrrolidone at a solid content of 15%. Then, 10wt% of pore-forming agent PVP was added, and the mixture was stirred at 60℃ for 4 hours until completely dissolved. After standing to remove bubbles, a uniform and transparent casting solution was obtained. The casting solution was then used to form a film on the pH-photothermal dual-response self-healing functional layer using a non-solvent-induced phase separation method. The film was immediately immersed in a 16℃ deionized water coagulation bath (pH 7.0) for solidification. After phase separation, solvent exchange and washing, a superhydrophobic separation functional layer (thickness 120μm, water contact angle 153.2°) was formed, resulting in a pH-photothermal dual-response self-healing separation membrane.

[0092] Example 2

[0093] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0094] Its preparation method includes the following steps:

[0095] Step 1: Preparation of pH-photothermal dual-response self-healing composite material

[0096] Step 1-1, Mineral Activation: Rod-shaped or fibrous silicate minerals (sepiolite, fibrous) were calcined at 400℃ for 2.5 hours at a rate of 5℃ / min. After cooling, 5 mol / L hydrochloric acid was added at a solid-liquid ratio of 1 g:10 mL under stirring, and the mixture was refluxed at 85℃ for 5 hours. After centrifugation, the solid was collected, washed until neutral, dried under vacuum at 80℃, ground, and passed through a 200-mesh sieve to obtain the activated carrier (specific surface area 180 m²). 2 / g);

[0097] Steps 1-2: Photothermal material loading: Disperse 0.5g of the activated support in 50mL of deionized water, then add 0.06g of the photothermal material MXene (Ti3C2T). xThe pH was adjusted to 10.5, and the mixture was subjected to hydrothermal reaction at 130℃ for 10 hours. After washing and drying, the composite material sepiolite@MXene loaded with photothermal material was obtained (the loading amount of photothermal material MXene was 11.5 wt%, and the particle size was 10-18 nm).

[0098] Steps 1-3, loading of repair agent: 1.0g of the composite material sepiolite@MXene loaded with photothermal material was dispersed in 50mL of ethanol, 0.28g of hydrophobic silane (perfluorooctyltrimethoxysilane) and 0.12g of repair agent 2-mercaptobenzimidazole were added, ultrasonic treatment was carried out for 20min, and then stirred and adsorbed at 20℃~30℃ for 18h. After centrifugation and drying, the composite material loaded with photothermal material-repair agent was obtained.

[0099] Steps 1-4, pH-responsive gated encapsulation: Disperse 0.5g of the composite material loaded with photothermal material-repair agent in 50mL of acetate buffer solution with pH 4.2, then add 0.22g of hydrophilic polymer carboxymethyl chitosan (DD82%, 20kDa), and dropwise add 0.6mL of crosslinking agent solution (25wt% glutaraldehyde aqueous solution). Perform crosslinking reaction at 35℃ for 5h (the degree of crosslinking is 70% according to the ninhydrin colorimetric method). Wash and dry to obtain pH-photothermal dual-responsive self-healing composite material.

[0100] Step 2: Preparation of pH-photothermal dual-responsive self-healing functional layer: The pH-photothermal dual-responsive self-healing composite material was dispersed in water-based acrylic resin at a concentration of 6 wt%, and 0.5 wt% dispersant BYK-190 was added. The dispersion temperature was controlled at 35℃, and the mixture was stirred and dispersed evenly to obtain the self-healing material. Then, the self-healing material was sprayed onto the surface of the support layer (250 μm PP non-woven support layer), the wet film was 60 μm, and it was cured at 70℃ for 2.5 h to form the pH-photothermal dual-responsive self-healing functional layer (dry film approximately 13 μm).

[0101] Step 3: Preparation of the superhydrophobic separation functional layer: Hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and polymer PES were compounded at a mass ratio of 1:5. The hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and PES were dissolved in NMP at a solid content of 16%. Then, 12wt% of pore-forming agent PEG (molecular weight 6000) was added and stirred evenly to obtain a casting solution. The casting solution was then used to form a film on the pH-photothermal dual-response self-healing functional layer using a non-solvent-induced phase separation method. The film was immediately immersed in a 16℃ deionized water coagulation bath (pH 7.0) for solidification to form a superhydrophobic separation functional layer (thickness 130μm, water contact angle 151.7°), thus obtaining a pH-photothermal dual-response self-healing separation membrane.

[0102] Example 3

[0103] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0104] Its preparation method includes the following steps:

[0105] Step 1: Preparation of pH-photothermal dual-response self-healing composite material

[0106] Step 1-1, Mineral Activation: The rod-shaped or fibrous silicate mineral (attapulgite, rod-shaped crystals) is calcined at 300℃ for 2 hours at a rate of 5℃ / min. After cooling, 6mol / L hydrochloric acid is added at a solid-liquid ratio of 1g:10mL under stirring, and the mixture is refluxed at 80℃ for 4 hours. After centrifugation, the solid is collected, washed until neutral, vacuum dried at 80℃, ground, and sieved through a 200-mesh sieve to obtain the activated carrier (specific surface area 215m²). 2 / g);

[0107] Steps 1-2: Photothermal material loading: 0.5 g of activated carrier was dispersed in 50 mL of deionized water, and then 0.10 g of carboxylated multi-walled carbon nanotubes (MWCNT-COOH, length 0.5-2 μm, diameter 10-20 nm) were added. The mixture was ultrasonically dispersed for 30 min, the pH was adjusted to 10, and the mixture was hydrothermally reacted at 120 °C for 12 hours. After centrifugation, washing, and drying, the composite material ATP@CNT loaded with photothermal material was obtained. [The theoretical loading of the photothermal material carbon nanotubes was 9.8 wt% (calculated based on the mass ratio of the feed materials). The actual loading was determined to be 8.2 wt% by thermogravimetric analysis (TGA, nitrogen atmosphere, heating rate 10 °C / min, from room temperature to 800 °C).]

[0108] Steps 1-3: Loading the repair agent: Disperse 1.0g of the composite material ATP@CNT loaded with the photothermal material in 50mL of ethanol, add 0.25g of hydrophobic silane (perfluorodecyltrimethoxysilane) and 0.15g of the repair agent benzotriazole (BTA), sonicate for 15min, then stir and adsorb at 20℃~30℃ for 12h, centrifuge and dry to obtain the composite material loaded with photothermal material-repair agent.

[0109] Steps 1-4, pH-responsive gated encapsulation: 0.5g of the composite material loaded with photothermal material-repair agent was dispersed in 50mL of acetate buffer solution with pH 4.5, then 0.2g of hydrophilic polymer chitosan (DD92%, 15kDa) was added, and 0.3mL of crosslinking agent solution (25wt% glutaraldehyde aqueous solution) was added dropwise. The crosslinking reaction was carried out at 40℃ for 4h (the degree of crosslinking was 55% according to the ninhydrin colorimetric method). After washing and drying, the pH-photothermal dual-responsive self-healing composite material was obtained.

[0110] Step 2: Preparation of the photothermal dual-response self-healing functional layer: The pH-photothermal dual-response self-healing composite material is dispersed in waterborne polyurethane resin at a concentration of 5 wt%, and the dispersion temperature is controlled at 35℃ while stirring to achieve uniform dispersion, thus obtaining the self-healing material; then, the self-healing material is coated onto the surface of the support layer (200μm PTFE support layer) with a doctor blade, forming a wet film of 50μm, and cured at 60℃ for 2 hours to form a pH-photothermal dual-response self-healing functional layer (dry film of approximately 12μm);

[0111] Step 3: Preparation of the superhydrophobic separation functional layer: Hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and polymer PVDF are compounded at a mass ratio of 1:5. Then, the hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and PVDF are dissolved in N-methylpyrrolidone at a solid content of 15%. Then, 10wt% of pore-forming agent PVP is added and stirred evenly to obtain a casting solution. The casting solution is then used to form a film on the pH-photothermal dual-response self-healing functional layer using a non-solvent-induced phase separation method. The film is immediately immersed in a 16℃ deionized water coagulation bath (pH 7.0) for solidification to form a superhydrophobic separation functional layer (thickness 120μm, water contact angle 153.2°), thus obtaining a pH-photothermal dual-response self-healing separation membrane.

[0112] Example 4

[0113] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0114] Its preparation method includes the following steps:

[0115] Step 1: Preparation of pH-photothermal dual-response self-healing composite material

[0116] Step 1-1, Mineral Activation: Rod-shaped or fibrous silicate minerals (sepiolite, fibrous) were calcined at 350℃ for 2.5 hours at a rate of 5℃ / min. After cooling, 7mol / L hydrochloric acid was added at a solid-liquid ratio of 1g:10mL under stirring, and the mixture was refluxed at 85℃ for 4 hours. After centrifugation, the solid was collected, washed until neutral, dried under vacuum at 80℃, ground, and passed through a 200-mesh sieve to obtain the activated carrier (specific surface area 198m²). 2 / g);

[0117] Steps 1-2: Photothermal material loading: The process was carried out according to the method in Example 2, and the MXene loading of the photothermal composite material sepiolite@MXene was 12.1 wt%, with a particle size of 10-18 nm.

[0118] Steps 1-3: Loading the repair agent: Disperse 1.0g of the composite material sepiolite@MXene loaded with photothermal material in 50mL of ethanol, add 0.28g of hydrophobic silane (perfluorooctyltrimethoxysilane) and 0.13g of the repair agent 2-mercaptobenzothiazole, sonicate for 20min, then stir and adsorb at 20℃~30℃ for 20h, centrifuge and dry to obtain the composite material loaded with photothermal material-repair agent.

[0119] Steps 1-4, pH-responsive gated encapsulation: 0.5g of the composite material loaded with photothermal material-repair agent was dispersed in 50mL of acetate buffer solution with pH 4.2, then 0.22g of hydrophilic high molecular weight carboxymethyl chitosan (DD82%, 20kDa) was added, and 0.6mL of crosslinking agent solution (25wt% glutaraldehyde aqueous solution) was added dropwise. The crosslinking reaction was carried out at 35℃ for 5h (the degree of crosslinking was determined to be 70% according to the ninhydrin colorimetric method). After washing and drying, the pH-photothermal dual-responsive self-healing composite material was obtained.

[0120] Step 2: Preparation of pH-photothermal dual-responsive self-healing functional layer: The pH-photothermal dual-responsive self-healing composite material was dispersed in water-based acrylic resin at a concentration of 7 wt%, and 0.5 wt% dispersant BYK-190 was added. The dispersion temperature was controlled at 35℃ and the mixture was stirred until uniformly dispersed to obtain the self-healing material. Then, the self-healing material was sprayed onto the surface of the support layer (250 μm PP non-woven support layer), the wet film was 60 μm, and it was cured at 70℃ for 2 hours to form a pH-photothermal dual-responsive self-healing functional layer (dry film approximately 15 μm).

[0121] Step 3: Preparation of the superhydrophobic separation functional layer: Hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and polymer PES are compounded at a mass ratio of 1:5. The hydrophobic modified silicate mineral and PES are dissolved in NMP at a solid content of 14%. Then, 8wt% of pore-forming agent PVP is added and stirred evenly to obtain a casting solution. The casting solution is then used to form a film on the pH-photothermal dual-response self-healing functional layer using a non-solvent-induced phase separation method. The film is then solidified in a 16℃ deionized water coagulation bath (pH 7.0) to form a superhydrophobic separation functional layer (thickness 110μm, water contact angle 152.5°), thus obtaining a pH-photothermal dual-response self-healing separation membrane.

[0122] Example 5

[0123] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0124] Its preparation method includes the following steps:

[0125] Steps 1-2 are the same as in Example 1;

[0126] Step 3: Preparation of the superhydrophobic separation functional layer: Hydrophobic modified silicate minerals (perfluorodecyltrimethoxysilane-modified attapulgite) and polymers were compounded at a mass ratio of 1:4. Then, the hydrophobic modified silicate minerals (perfluorodecyltrimethoxysilane-modified attapulgite) and polyvinylidene fluoride (PVDF concentrated dispersion, 60% solid content) were dispersed in NMP at a solid content of 18%. Then, 10wt% of pore-forming agent PEG-6000 was added and stirred until homogeneous to obtain the casting solution. The casting solution was then used to form a film on the pH-photothermal dual-response self-healing functional layer using a solvent-inducing phase separation method. The film was then cured in a 16℃ deionized water coagulation bath (pH 7.0) to form a superhydrophobic separation functional layer (thickness 140μm, water contact angle 154.8°). This yielded a pH-photothermal dual-response self-healing separation membrane.

[0127] Example 6

[0128] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0129] Its preparation method includes the following steps:

[0130] Step 1, Preparation of pH-photothermal dual-response self-healing composite material: Same as Example 1.

[0131] Step 2: Preparation of pH-photothermal dual-responsive self-healing functional layer: The pH-photothermal dual-responsive self-healing composite material is dispersed in waterborne polyurethane resin at a concentration of 3wt%, and 0.5wt% of dispersant BYK-190 is added. The dispersion temperature is controlled at 35℃ and the mixture is stirred and dispersed evenly to obtain the self-healing material. Then, the self-healing material is coated onto the surface of the support layer (200μm PTFE support layer) using a doctor blade. The wet film is 25μm thick and cured at 60℃ to form the pH-photothermal dual-responsive self-healing functional layer (dry film thickness is about 9μm).

[0132] Step 3: Preparation of superhydrophobic separation functional layer: Same as in Example 1.

[0133] Example 7

[0134] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0135] Its preparation method includes the following steps:

[0136] Step 1: Preparation of pH-photothermal dual-response self-healing composite material

[0137] Step 1-1, Mineral Activation: The raw rod-shaped or fibrous silicate mineral (attapulgite, rod-shaped crystals) is calcined at 450℃ for 1.5 hours at a rate of 5℃ / min. After cooling, 5 mol / L hydrochloric acid is added at a solid-liquid ratio of 1 g:10 mL under stirring, and the mixture is refluxed at 75℃ for 5 hours. After centrifugation, the solid is collected, washed until neutral, vacuum dried at 80℃, ground, and sieved through a 200-mesh sieve to obtain the activated carrier (specific surface area 235 m²). 2 / g).

[0138] Steps 1-2: Photothermal material loading: 0.5 g of the activated carrier was dispersed in 50 mL of deionized water, and then 0.065 g of graphene oxide (GO, monolayer ratio >90%) was added. The mixture was ultrasonically dispersed for 60 min, the pH was adjusted to 10, 0.01 g of hydrazine hydrate was added, and the reduction reaction was carried out at 90 °C for 6 h. The mixture was centrifuged, washed until neutral, and dried to obtain the composite material ATP@rGO loaded with photothermal material (loaded by 10.2 wt% based on the photothermal material rGO).

[0139] Steps 1-3, loading of repair agent: 1.0g of the composite material ATP@rGO loaded with photothermal material was dispersed in 50mL of ethanol, 0.22g of hydrophobic silane (perfluorodecyltrimethoxysilane) and 0.18g of repair agent 2-mercaptobenzimidazole were added, ultrasonic treatment was carried out for 20min, and then stirred and adsorbed at 20℃~30℃ for 24h. After centrifugation and drying, the composite material loaded with photothermal material-repair agent was obtained.

[0140] Steps 1-4, pH-responsive gated encapsulation: Disperse 0.5g of the composite material loaded with photothermal material-repair agent in 50mL of acetate buffer solution with pH 4.8, then add 0.18g of hydrophilic polymer chitosan (DD85%, 25kDa), and dropwise add 0.4mL of crosslinking agent solution (25wt% glutaraldehyde aqueous solution). Perform crosslinking reaction at 45℃ for 3h (the degree of crosslinking is 60% according to the ninhydrin colorimetric method). Wash and dry to obtain pH-photothermal dual-responsive self-healing composite material.

[0141] Step 2: Preparation of pH-photothermal dual-response self-healing functional layer: The pH-photothermal dual-response self-healing composite material is dispersed in water-based polyurethane at a concentration of 4wt%, and the dispersion temperature is controlled at 35℃. The mixture is stirred and dispersed evenly to obtain the self-healing material. Then, the self-healing material is coated onto the surface of the support layer (200μm PTFE support layer) with a doctor blade. The wet film is 45μm thick and cured at 70℃ for 1.5h to form the pH-photothermal dual-response self-healing functional layer (dry film is about 10μm thick).

[0142] Step 3: Preparation of the superhydrophobic separation functional layer: Hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and polymer PVDF are compounded at a mass ratio of 1:4. The hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and PVDF are dissolved in NMP at a solid content of 16%. Then, 12wt% of pore-forming agent PVPK30 is added and stirred evenly to obtain a casting solution. The casting solution is then used to form a film on the pH-photothermal dual-response self-healing functional layer using a non-solvent-induced phase separation method. The film is then solidified in a 16℃ deionized water coagulation bath (pH 7.0) to form a superhydrophobic separation functional layer (thickness 100μm, water contact angle 152.8°), thus obtaining a pH-photothermal dual-response self-healing separation membrane.

[0143] Example 8

[0144] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0145] Its preparation method includes the following steps:

[0146] Step 1, same as in Example 1.

[0147] Step 2: Preparation of pH-photothermal dual-responsive self-healing functional layer: The pH-photothermal dual-responsive self-healing composite material is dispersed in waterborne polyurethane resin at a concentration of 5 wt%, and 0.5 wt% dispersant BYK-190 is added. The dispersion temperature is controlled at 35℃ and the mixture is stirred and dispersed evenly to obtain the self-healing material. Then, the self-healing material is coated onto the surface of the support layer (200 μm polytetrafluoroethylene porous support layer, pore size 0.22 μm) using a doctor blade. The wet film is 50 μm thick and cured at 65℃ for 2 hours to form a pH-photothermal dual-responsive self-healing functional layer (dry film approximately 12 μm thick).

[0148] Step 3: Preparation of the superhydrophobic separation functional layer: Hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and polymer PES were compounded at a mass ratio of 1:5. The hydrophobic modified silicate mineral (perfluorodecyltrimethoxysilane modified attapulgite) and PES were dissolved in NMP at a solid content of 14%. Then, 15wt% of pore-forming agent PEG-4000 was added and stirred evenly to obtain a casting solution. The casting solution was then used to form a film on the pH-photothermal dual-response self-healing functional layer using a non-solvent-induced phase separation method. The film was then cured in a 16℃ deionized water coagulation bath (pH 7.0) to form a superhydrophobic separation functional layer (thickness 110μm, water contact angle 151.5°), thus obtaining a pH-photothermal dual-response self-healing separation membrane.

[0149] Example 9

[0150] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0151] Its preparation method includes the following steps:

[0152] Step 1: Preparation of pH-photothermal dual-response self-healing composite material

[0153] Step 1-1, Mineral Activation: The raw rod-shaped or fibrous silicate mineral (attapulgite, rod-shaped crystals) is roasted at 500℃ for 1 hour at a rate of 5℃ / min. After cooling, 8 mol / L hydrochloric acid is added at a solid-liquid ratio of 1g:10mL under stirring, and the mixture is refluxed at 90℃ for 2 hours. After centrifugation, the solid is collected, washed until neutral, dried under vacuum at 80℃, ground, and sieved through a 200-mesh sieve to obtain the activated carrier (specific surface area 275m²). 2 / g);

[0154] Steps 1-2, Photothermal material loading: Same as in Example 1, to obtain the composite material ATP@CeO2 loaded with photothermal material (loaded at 14.5wt% based on photothermal material CeO2, with a particle size of 5-12nm).

[0155] Steps 1-3: Loading the repair agent: Disperse 1.0g of the composite material ATP@CeO2 loaded with the photothermal material in 50mL of ethanol, add 0.26g of hydrophobic silane (perfluorodecyltrimethoxysilane) and 0.16g of the repair agent 2-mercaptobenzothiazole, sonicate for 15min, then stir and adsorb at 20℃~30℃ for 26h, centrifuge and dry to obtain the composite material loaded with photothermal material-repair agent.

[0156] Steps 1-4, pH-responsive gated encapsulation: Disperse 0.5g of the composite material loaded with photothermal material-repair agent in 50mL of acetate buffer solution with pH 4.0, then add 0.26g of hydrophilic polymer chitosan (DD90%, 10kDa), and dropwise add 0.65mL of crosslinking agent solution (25wt% glutaraldehyde aqueous solution). Perform crosslinking reaction at 50℃ for 2h (the degree of crosslinking is 80% as determined by the ninhydrin colorimetric method). Wash and dry to obtain pH-photothermal dual-responsive self-healing composite material.

[0157] Step 2: Preparation of pH-photothermal dual-response self-healing functional layer: The pH-photothermal dual-response self-healing composite material was dispersed in waterborne polyurethane at a concentration of 8 wt%, and 0.5 wt% of dispersant BYK-190 was added. The dispersion temperature was controlled at 35℃ and the mixture was stirred and dispersed evenly to obtain the self-healing material. Then, the self-healing material was coated onto the surface of the support layer (200μm PTFE support layer) using a scraper, with a wet film thickness of 90μm (using a multi-coat process, with each wet film thickness of about 30μm, coated in 3 coats). The coating was cured at 85℃ for 1 hour to form a pH-photothermal dual-response self-healing functional layer (dry film thickness of about 20μm).

[0158] Step 3: Preparation of superhydrophobic separation functional layer: Same as in Example 1, the thickness of the formed superhydrophobic separation functional layer is 200 μm and the water contact angle is 155.0°.

[0159] Example 10

[0160] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0161] Its preparation method includes the following steps:

[0162] Step 1, same as in Example 1.

[0163] Step 2 is the same as step 2 in the embodiment, except that the polyvinylidene fluoride (PVDF) porous support layer (180μm thick) is cured at 65°C for 2 hours, and the dry film thickness is about 12μm.

[0164] Step 3, same as in Example 1.

[0165] Comparative Example 1

[0166] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0167] The preparation method includes the following steps: the same as in Example 1, except that the pH-responsive gating encapsulation in steps 1-4 is omitted, and the composite material of loaded photothermal material-repair agent prepared in steps 1-3 is directly used to prepare the pH-photothermal dual-responsive self-repairing functional layer in step 2.

[0168] Comparative Example 2

[0169] A pH-responsive self-healing separation membrane includes a support layer, a pH-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0170] The preparation method includes the following steps: the same as in Example 2, except that the photothermal material loading step 1-2 is omitted, and the activated carrier prepared in step 1-1 is directly used for the repair agent loading in step 1-3.

[0171] Comparative Example 3

[0172] A pH-photothermal dual-responsive self-healing separation membrane includes a support layer, a pH-photothermal dual-responsive self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0173] The preparation method includes the following steps: same as in Example 2; the difference is that the amount of MXene in steps 1-2 is adjusted to 0.125g and the MXene loading is adjusted to 25wt%.

[0174] Comparative Example 4

[0175] A pH-photothermal dual-response separation membrane includes a PTFE support membrane, a pH-photothermal dual-response functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0176] The preparation method includes the following steps: the same as in Example 1, except that the repair agent loading step 1-3 is omitted, and the composite material ATP@CeO2 loaded with photothermal material prepared in step 1-2 is directly encapsulated in step 1-4 by pH response gating.

[0177] Comparative Example 5

[0178] A separation membrane includes a support layer and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0179] Its preparation method includes the following steps:

[0180] Hydrophobically modified silicate minerals (perfluorodecyltrimethoxysilane modified attapulgite) and PVDF were compounded at a mass ratio of 1:5, dissolved in N-methylpyrrolidone at a solid content of 15%, and 10wt% pore-forming agent PVP was added. The mixture was stirred evenly to obtain the casting solution.

[0181] The casting solution was directly deposited on the surface of a 200μm PTFE support layer using a non-solvent-induced phase separation method. The film was then immediately immersed in a deionized water coagulation bath for curing, forming a superhydrophobic separation functional layer with a thickness of 120μm and a water contact angle of 153.2°, thus obtaining the separation membrane.

[0182] Comparative Example 6

[0183] A dual-layer self-healing separation membrane includes, from bottom to top, a support layer, a photothermal responsive self-healing layer, a pH responsive self-healing layer, and a superhydrophobic separation functional layer.

[0184] Its preparation method includes the following steps:

[0185] Step 1: Preparation of composite material A: Mineral activation and photothermal material loading were carried out sequentially according to the method in Example 1 to obtain a composite material with only photothermal material loading, no repair agent, and no encapsulation layer, namely composite material A;

[0186] Step 2: Preparation of composite material B: Mineral activation, repair agent loading, and pH-responsive gating encapsulation were carried out sequentially according to the method in Example 1 to obtain a composite material that only loads the repair agent and performs pH encapsulation, without photothermal materials, namely composite material B;

[0187] Step 3: Preparation of the dual-layer, separate self-healing layer

[0188] ① Disperse composite material A at a concentration of 5 wt% in waterborne polyurethane, add 0.5 wt% BYK-190, and stir until uniform; apply to the surface of the support layer with a scraper, and cure at 60℃ for 2 hours to form a photothermal responsive layer;

[0189] ② Disperse composite material B at a concentration of 5 wt% in waterborne polyurethane and stir until homogeneous; apply it to the photothermal response layer with a scraper and cure at 60℃ for 2 hours to form a pH response layer;

[0190] The total thickness of the two dry membrane layers is approximately 24 μm.

[0191] Step 4: Preparation of the superhydrophobic separation functional layer:

[0192] Hydrophobically modified silicate minerals (perfluorodecyltrimethoxysilane modified attapulgite) were compounded with PVDF at a mass ratio of 1:5, dissolved in N-methylpyrrolidone at a solid content of 15%, and 10wt% pore-forming agent PVP was added. The mixture was stirred evenly to obtain a casting solution. A film was formed on the pH-responsive layer using a non-solvent-induced phase separation method and solidified in a deionized water coagulation bath to form a superhydrophobic separation functional layer with a thickness of 120μm and a water contact angle of 153.2°, thus obtaining a double-layer separation self-healing separation membrane.

[0193] Although this comparative example consists of a photothermal-responsive self-healing layer and a pH-responsive self-healing layer, the two layers are physically separated, resulting in interfacial resistance. While near-infrared light can penetrate the upper pH-responsive self-healing layer, heat still needs to be conducted through the interface, reducing efficiency. Furthermore, the path for the repair agent to migrate from the pH-responsive self-healing layer to the damage site is longer, leading to a significantly lower repair efficiency compared to the integrated dual-response structure of this invention.

[0194] Comparative Example 7

[0195] A pH-photothermal dual-response self-healing separation membrane using rGO-SiO2 support comprises a support layer, a pH-photothermal dual-response self-healing functional layer, and a superhydrophobic separation functional layer arranged sequentially from bottom to top.

[0196] The preparation method is the same as in Example 1, except that the natural silicate mineral carrier of this invention is replaced by the commonly used synthetic material rGO-SiO2. The other raw materials, steps, and parameters are exactly the same, including the following steps:

[0197] Step 1: pH-photothermal dual-response self-healing composite material

[0198] Step 1-1, Preparation of rGO-SiO2 support: 2g of reduced graphene oxide (rGO) was mixed with 1000ml of deionized water and sonicated for 1h. The pH was then adjusted to 10 with 5wt% KOH. 30g of hexadecyltrimethylammonium bromide (CTAB) and 25g of tetraethyl orthosilicate (TEOS) were added. The reaction was carried out at 70℃ for 48h at 300rpm. After the reaction, the product was washed three times by centrifugation with a 3:1 mixture of ethanol and deionized water. Then, 500g of a 2:1 mixture of acetic acid and ethanol was added and reacted at room temperature for 24h. After standing for 8h, the product was washed five times by centrifugation with ethanol. Finally, the product was vacuum dried at room temperature for 72h to obtain the rGO-SiO2 support (spherical). This preparation method did not involve high-temperature calcination or acid activation treatment, and the resulting rGO-SiO2 support had a specific surface area of ​​125m². 2 / g.

[0199] Steps 1-2: Photothermal material loading: Same as in Example 1;

[0200] Steps 1-3: Repair agent loading: Same as in Example 1;

[0201] Steps 1-4: pH-responsive gating encapsulation: Same as Example 1;

[0202] Step 2, same as in Example 1;

[0203] Step 3, same as in Example 1.

[0204] Although this comparative example added the same amount of repair agent as in Example 1, the specific surface area of ​​the rGO-SiO2 carrier was only 125 m². 2 / g, which is far lower than that of activated attapulgite, cannot effectively adsorb and anchor the repair agent. A large amount of repair agent is only loosely attached to the surface, and pre-leakage and loss occur during subsequent film preparation and use, resulting in a significantly lower actual effective load.

[0205] Comparative Example 8

[0206] A self-healing separation membrane with pH-photothermal dual response using rGO-SiO2 support, compared with Comparative Example 7;

[0207] The preparation method includes the following steps: the same as Comparative Example 7, except that the rGO-SiO2 support is also activated;

[0208] The activation method is as follows: The rGO-SiO2 support prepared in Comparative Example 7 is placed in a muffle furnace and heated to 400℃ at a rate of 5℃ / min in air atmosphere, and calcined at a constant temperature for 2h to remove surface organic impurities and enhance the interfacial bonding between rGO and SiO2; after cooling, the powder is added to a 5mol / L hydrochloric acid solution and magnetically stirred and refluxed at 80℃ for 4h to etch the SiO2 surface through acid etching and introduce more hydroxyl active sites; after the reaction is completed, the mixture is centrifuged, repeatedly washed with deionized water until the filtrate is neutral, dried in a vacuum drying oven at 80℃ for 12h, ground and passed through a 200-mesh sieve to obtain the activated rGO-SiO2 support (spherical).

[0209] Subsequent steps using the activated rGO-SiO2 support yielded a self-healing separation membrane with dual pH and photothermal responses.

[0210] Although this comparative example increased the specific surface area, the carrier was still a spherical particle, lacking a through-pore channel, and the migration efficiency of the repair agent was still lower than that of the rod-shaped or fibrous silicate mineral carrier of this invention.

[0211] Example 1

[0212] The specific surface area and functional group density of the activated supports prepared in Examples 1, 2 and 7-8 were measured, and the results are shown in Table 1.

[0213] Specific surface area determination method: The Brunauer-Emmett-Teller (BET) nitrogen adsorption method was used to determine the nitrogen adsorption-desorption isotherm of the sample at 77 K, and the specific surface area, pore size distribution and pore volume were calculated.

[0214] Method for determining functional group density: The sample was dispersed in deionized water and titrated with 0.01 mol / L NaOH standard solution using potentiometric titration. The pH change point was recorded, and the molar content of active functional groups such as surface hydroxyl (-OH) and carboxyl (-COOH) was calculated in μmol / g.

[0215] Table 1. Comparison of the structure and surface properties of the activated support of the present invention and the synthetic support of the prior art.

[0216]

[0217] As shown in Table 1, the rod-shaped or fibrous silicate minerals (attapulgite, sepiolite) treated by the roasting + acid activation process of this invention can achieve a specific surface area of ​​210–275 m². 2The functional group density can reach 376–468 μmol / g, which is much higher than that of the rGO-SiO2 support used in Comparative Examples 7–8. The specific surface area of ​​the unactivated rGO-SiO2 support in Comparative Example 7 is only 125 m² / g. 2 / g, with a functional group density of only 180μmol / g; after roasting and acid activation, the specific surface area and functional group density of Comparative Example 8 were slightly increased, but were still significantly lower than those of the natural mineral carrier of this invention.

[0218] Meanwhile, the attapulgite, sepiolite, and malachite of this invention possess a continuous, interconnected one-dimensional pore structure, providing ample anchoring points for photothermal materials and a rapid channel for the storage and controlled transport of the remediation agent. In contrast, rGO-SiO2 consists of spherical particles with discontinuous pores and no interconnected mesoporous channels, making it impossible to achieve efficient loading and stable controlled release of the remediation agent. These results demonstrate that the rod-shaped or fibrous silicate minerals selected in this invention, after activation, exhibit significant advantages in specific surface area, number of active sites, and pore structure, clearly superior to the commonly used rGO-SiO2 carrier in existing technologies. They represent a key carrier structure for achieving efficient photothermal conversion and precise controlled-release remediation.

[0219] Example 2: Photothermal conversion performance test

[0220] 1. The separation membranes prepared in each embodiment and comparative example were irradiated with 808nm laser light (0.5W / cm²) using an infrared thermal imager. 2 The temperature change of the membrane surface during irradiation was detected, and the photothermal conversion efficiency was calculated according to the following formula; the results are shown in Table 2. Among them, the infrared thermal imaging image of the separation membrane during the photothermal repair process in Example 1 is shown below. Figure 3 As shown.

[0221] Formula for calculating photothermal conversion efficiency:

[0222] ;

[0223] Where: η—photothermal conversion efficiency, %; h—heat transfer coefficient; S—effective irradiated area; T max —Equilibrium temperature; T surr —Ambient temperature; Q dis —Heat loss; I—Illumination power density; A—Absorbance at illumination wavelength.

[0224] 2. Infrared thermal imaging results:

[0225] Figure 3The photothermal self-healing kinetics of the pH-photothermal dual-response self-healing separation membrane (attapulgite-supported nano-CeO2-based) of Example 1 are presented intuitively: Under irradiation with 808nm near-infrared light, the membrane surface can rapidly heat up to 68.7℃ within 30s and reach a thermal equilibrium temperature of 72.1℃ within 60s, forming a precise repair temperature window of 68.7℃~72℃ (higher than the response threshold of the chitosan cross-linked encapsulation layer, about 55℃); the heat-affected zone can diffuse in a controllable manner, triggering the thermal swelling of the chitosan cross-linked network only in local areas, releasing the internally loaded 2-mercaptobenzothiazole repair agent, filling microcracks and repairing interface damage; the entire photothermal triggering and repair process is fast and efficient, and the oil-water separation efficiency and flux recovery rate of the repaired membrane can reach more than 95%.

[0226] In summary, this invention, through the multifunctional integrated design of a natural silicate mineral carrier, not only achieves superhydrophobic and efficient oil-water separation (water contact angle ≥150°) and dye retention in dyeing and printing wastewater, but also endows the membrane with a gentle, rapid, and controllable photothermal in-situ self-healing capability. This solves the common industry pain point of irreversible performance degradation caused by physical scratches and chemical corrosion during long-term use of existing separation membranes, enabling online repair of membrane modules without downtime disassembly, and significantly reducing industrial operation and maintenance costs.

[0227] 3. Photothermal conversion performance test results

[0228] Table 2. Test results of photothermal conversion performance

[0229]

[0230] As shown in Table 2:

[0231] Example 1 uses nano-cerium oxide as the photothermal material, which heats up to 68.7℃ within 30 seconds, far exceeding the softening / response threshold (approximately 55℃) of the chitosan encapsulation layer. Example 2 uses MXene as the photothermal material, exhibiting uniform heating and stable heat distribution. Example 3 uses carbon nanotubes as the photothermal material, with a photothermal conversion efficiency of 38.4%, slightly lower than the nano-cerium oxide system. However, the carbon nanotubes form continuous thermal conduction pathways along the axial orientation of the one-dimensional rod-shaped mineral, resulting in a faster heating response and facilitating rapid triggering of repair. Example 7 uses reduced graphene oxide (rGO) as the photothermal material, achieving a photothermal conversion efficiency of 40.8%. Example 9 uses low molecular weight chitosan (10kDa) and a high specific surface area carrier (275m³). 2 / g) Synergistic effect: Low molecular weight chitosan makes the cross-linked network segments shorter, the thermal response more sensitive, and the heating rate faster; the high specific surface area carrier makes the photothermal material more uniformly dispersed, reduces local hot spots, and improves the overall photothermal conversion efficiency to 45.2%.

[0232] All embodiments of the present invention exhibit excellent photothermal response and heating capability: within 30 seconds of irradiation with 808nm near-infrared laser, all embodiments can rapidly heat up to above 63.8℃, and the equilibrium temperature can reach above 67.6℃. The photothermal conversion efficiency is between 37.9% and 45.2%, which is much higher than that of the comparative embodiments. It can quickly reach the encapsulation layer repair trigger temperature (55℃) and meet the requirements for in-situ rapid repair.

[0233] Comparative Examples 1-5 exhibited significantly reduced photothermal performance due to structural defects. Specifically, Comparative Example 5, lacking any photothermal material, showed only a slight temperature increase of approximately 2.4°C after 808nm laser irradiation, far below the response threshold (55°C) of the chitosan encapsulation layer, thus failing to achieve photothermal triggering repair. Comparative Example 6, employing a dual-layer separation structure, resulted in a longer heat conduction path and significantly reduced efficiency. Comparative Example 7, using an unactivated rGO-SiO2 carrier, while capable of heating to the trigger temperature under laser irradiation, suffered from uneven distribution of the photothermal material and significant pre-leakage of the repair agent due to its low specific surface area, lack of interconnected mesoporous channels, and weak adsorption and anchoring ability of the repair agent, leading to a severe shortage of effective repair agent. Furthermore, the spherical nature of rGO-SiO2 particles, lacking continuous transport channels, resulted in high resistance to repair agent migration and uncontrollable release, achieving only photothermal heating but failing to achieve stable and efficient self-repair, thus further impacting its repair effect. Although Comparative Example 8 activated rGO-SiO2, resulting in an increase in specific surface area and functional group density, it was still significantly lower than the natural fibrous mineral carrier of the present invention. Furthermore, rGO-SiO2 consists of spherical particles with discontinuous pores and no interconnected channels, leading to high resistance to the transport of the repair agent and low release efficiency. Therefore, the repair performance was slightly improved but still far lower than that of the present invention.

[0234] In summary, the selection of rod-shaped / fibrous silicate mineral carriers, the loading of photothermal materials (5-15 wt%), and the design of the integrated dual-response structure of this invention work together to achieve rapid, efficient, and stable photothermal conversion. The performance is significantly better than that of existing rGO-SiO2-based composite materials, providing reliable thermal triggering conditions for in-situ rapid self-healing.

[0235] Example 3: Performance Testing

[0236] 1. Oily wastewater separation and self-healing performance test

[0237] The separation membranes prepared in each embodiment and comparative example were used to simulate the treatment of oily wastewater, and their initial oil-water separation efficiency and flux were measured; the oil-water separation repair efficiency and flux recovery rate after mechanical scratches; and the oil-water separation repair efficiency and flux recovery rate after alkaline corrosion. The results are shown in Table 3.

[0238] Initial oil-water separation efficiency %: Simulated oily wastewater was prepared using a hexane / water volume ratio of 1:9, and dead-end filtration was performed at an operating pressure of 0.1 MPa. The oil content of the filtrate was measured, and the separation efficiency was calculated according to the following formula.

[0239] ;

[0240] ;

[0241] Repair efficiency and flux recovery rate after mechanical scratches: An 80μm standard scratch was applied to the surface of the separation membrane's functional layer. The oil-water separation efficiency and flux after the scratch were measured. Then, photothermal in-situ repair was performed using an 808nm laser for 5 minutes. The oil-water separation efficiency and flux after repair were measured, and the repair efficiency and flux recovery rate of the mechanical scratch were calculated. Repair efficiency test after alkaline corrosion: The separation membrane was immersed in a NaOH aqueous solution with a pH of 11 for 2 hours. After removal, it was rinsed with deionized water until neutral. The oil-water separation efficiency and flux after damage were measured. Then, the membrane was placed in an acetate buffer solution with a pH of 3 for 30 minutes for pH-responsive repair (this condition applies to all embodiments and is within the acidic triggering mechanism range (pH 3-5). After removal, it was rinsed with deionized water until neutral. The oil-water separation efficiency and flux after repair were measured, and the alkali corrosion oil-water separation repair efficiency % and alkali corrosion flux recovery rate were calculated.

[0242] Table 3. Test results of oily wastewater separation and self-healing performance.

[0243]

[0244] Note: Comparative Example 5 is a blank control group with no self-repair function. The values ​​in the table represent the performance retention rate.

[0245] 2. Performance testing of dye wastewater

[0246] The separation membranes prepared in each embodiment and comparative example were used to simulate the treatment of dye wastewater, and the initial dye rejection rate and flux, the dye rejection repair efficiency and flux recovery rate after mechanical scratching, and the dye rejection repair efficiency and flux recovery rate after alkali corrosion were measured. The results are shown in Table 4.

[0247] Initial dye rejection rate and flux: Methylene blue was used to simulate dye wastewater (concentration 50 mg / L). Dead-end filtration was performed at 0.1 MPa. The absorbance of the filtrate was measured to calculate the dye rejection rate, and the water flux was calculated using the volume-area-time method.

[0248] Repair efficiency and flux recovery rate after mechanical scratching: An 80 μm scratch was applied to the surface of the separation layer of the separation membrane, and the dye retention rate and flux were measured after the scratching. Photothermal repair was performed using 808 nm laser irradiation for 5 min, and the post-repair performance was measured. The repair efficiency (%) of dye retention after mechanical scratching and the flux recovery rate (%) were calculated.

[0249] Repair efficiency test after alkaline corrosion: The separation membrane was immersed in NaOH aqueous solution with pH 11 for 2 hours, and then rinsed with deionized water until neutral. The dye rejection rate and flux after damage were measured. Then, the membrane was placed in acetate buffer with pH 3 for 30 minutes for pH response repair. After removal, it was rinsed with deionized water until neutral. The dye rejection rate and flux after repair were measured. The alkaline corrosion dye rejection repair efficiency % and alkaline corrosion flux recovery rate were calculated.

[0250] Table 4. Test results of dye removal performance in dyeing and printing wastewater

[0251]

[0252] Note: Comparative Example 5 is a blank control group with no self-repair function; its data represents the performance retention rate.

[0253] 3. Performance testing in industrial wastewater treatment

[0254] The separation membranes prepared in each embodiment and comparative example were used to treat simulated industrial mixed wastewater (containing oil and dye), and the initial oil rejection rate, initial dye rejection rate and flux were measured. The oil rejection repair efficiency, dye rejection repair efficiency and flux recovery rate after mechanical scratching were also measured. The oil rejection repair efficiency, dye rejection repair efficiency and flux recovery rate after alkaline corrosion were also measured. The results are shown in Table 5.

[0255] Initial oil rejection rate, initial dye rejection rate, and flux: Simulated industrial mixed wastewater was prepared by mixing n-hexane (oil phase) and methylene blue solution (dye phase, concentration 50 mg / L) at a volume ratio of 1:9 and subjected to dead-end filtration at an operating pressure of 0.1 MPa. The initial oil rejection rate was calculated by measuring the oil content of the filtrate, the initial dye rejection rate was calculated by measuring the absorbance of the filtrate, and the water flux was calculated.

[0256] Repair efficiency and flux recovery rate after mechanical scratches: The surface of the separation functional layer of the separation membrane was subjected to 80μm standard scratch treatment, and the oil rejection rate, dye rejection rate and flux were measured after scratching. Photothermal in-situ repair was performed by irradiating with 808nm laser for 5min, and the various properties after repair were measured. The repair efficiency of oil rejection, repair efficiency of dye rejection and mechanical scratches and flux recovery rate after mechanical scratches were calculated.

[0257] Repair efficiency test after alkaline corrosion: The separation membrane was immersed in NaOH aqueous solution with pH 11 for 2 hours, and then rinsed with deionized water until neutral. The oil-water separation efficiency and flux after damage were measured. Then, the membrane was placed in acetate buffer solution with pH 3 for 30 minutes for pH response repair. After being removed, it was rinsed with deionized water until neutral. The oil-water separation efficiency and flux after repair were measured. The repair efficiency of oil retention, repair efficiency of dye retention, and flux recovery rate after alkaline corrosion were calculated.

[0258] Table 5 Treatment performance of industrial mixed wastewater (containing oil and dye)

[0259]

[0260] Note: Comparative Example 5 is a blank control group with no self-repair function; its data represents the performance retention rate.

[0261] From Tables 3 to 5, we can see that:

[0262] 1. The separation membranes prepared in Examples 1-8 of this invention exhibit high initial oil-water separation efficiency / initial oil rejection rate, initial dye rejection rate, and initial flux when treating oily wastewater, dye wastewater, and mixed industrial wastewater. Compared with the comparative examples, the differences are relatively small. However, after mechanical scratches and alkali corrosion damage, the separation membranes prepared in Examples 1-8, due to their dual-response integrated structure and natural mineral carrier design, can effectively achieve rapid in-situ repair of membrane damage. The mechanical scratch repair efficiency / mechanical scratch repair rejection rate, mechanical scratch flux recovery rate, alkali corrosion repair efficiency / alkali corrosion repair rejection rate, and alkali corrosion flux recovery rate are much higher than those of the comparative examples. After mechanical scratches or alkali corrosion damage, they can achieve efficient in-situ self-repair, and the overall stability and service life are significantly improved.

[0263] 2. Comparative Example 1 lacked pH-responsive gating encapsulation, resulting in the absence of a controlled-release barrier for the repair agent. This made it prone to pre-leakage and burst release, preventing precise triggering and multiple cycle repairs. Consequently, its performance in mechanical scratch repair efficiency, alkaline corrosion repair efficiency, and flux recovery rate was significantly reduced.

[0264] 3. Comparative Example 2, lacking a photothermal material load, could not be repaired by laser irradiation, resulting in a significant decrease in its mechanical scratch repair efficiency and mechanical scratch flux recovery rate. However, the repair agent in the encapsulation layer of Comparative Example 2, under the localized stress caused by mechanical scratches, may leak to the damage site in small amounts. Simultaneously, the elastic recovery of the membrane substrate itself contributes to some performance recovery, thus exhibiting approximately 65% ​​"repair efficiency." This value primarily reflects elastic recovery rather than true self-repair.

[0265] 4. In Comparative Example 3, the excessive loading of photothermal material led to severe carrier agglomeration, membrane pore blockage, and decreased flux. Localized photothermal concentration caused excessive swelling and damage to the encapsulation layer, resulting in irregular leakage of the repair agent and a significant decrease in its performance in mechanical scratch repair, alkaline corrosion repair, and flux maintenance.

[0266] 5. Comparative Example 4, due to the omission of the repair agent load, resulted in no repair material filling after membrane damage, and the structural damage could not be restored, causing a significant decrease in its performance in mechanical scratch repair efficiency, alkali corrosion repair efficiency, and flux recovery rate.

[0267] 6. Comparative Example 5 has no repair function because it does not have a self-repair function layer.

[0268] 7. Comparative Example 6, due to its dual-layer separated structure, physically separates the photothermal-responsive self-healing layer and the pH-responsive self-healing layer. During mechanical scratches, laser irradiation only triggers the lower, thermally-responsive self-healing layer to heat up; heat must penetrate the upper, pH-responsive self-healing layer to act on the encapsulation structure, significantly reducing heat conduction efficiency. Simultaneously, the repair agent in the pH-responsive self-healing layer cannot be directly synergistically regulated by photothermal action, resulting in a slower response speed. During alkaline corrosion, although the pH-responsive self-healing layer can release the repair agent, interfacial resistance exists between the two layers, making the migration path of the repair agent to the damage site longer and more difficult. Ultimately, this leads to significantly lower repair efficiency and flux recovery rate after both mechanical scratches and alkaline corrosion compared to the integrated dual-response structure of this invention.

[0269] 8. In Comparative Example 7, after replacing the activated attapulgite soil of Example 1 with an unactivated rGO-SiO2 carrier using existing technology, the specific surface area of ​​the rGO-SiO2 carrier was only 125 m². 2 / g, which is much lower than the activated mineral carrier of this invention (210-275m). 2 / g), resulting in: 1) low and uneven loading of photothermal materials, with excessively high local hot spot temperatures causing localized over-softening or even damage to the encapsulation layer, forming non-selective leakage channels; 2) insufficient adsorption and anchoring capacity of the repair agent, with a large amount of repair agent only loosely adhering to the carrier surface, continuously being lost during film preparation, stirring, centrifugation, and long-term storage, resulting in a significantly lower content of effective repair agent actually participating in the repair compared to Examples 1-7. Therefore, although Comparative Example 7 can reach the trigger temperature under laser irradiation, the repair efficiency is far lower than that of this invention due to severe pre-loss of the repair agent, insufficient effective loading, and the lack of controlled-release selectivity of the repair agent release during thermal triggering (accompanied by random leakage). Its repair efficiency in various wastewater types is only maintained in the range of 62-65%.

[0270] 9. Although Comparative Example 8 subjected the existing rGO-SiO2 support to calcination and acid activation treatment (calcination at 400℃ for 2 hours, reflux at 80℃ with 5 mol / L hydrochloric acid for 4 hours), the specific surface area was increased to 152 m².2 / g, the functional group density increased to 245 μmol / g, but it is still significantly lower than the activated attapulgite clay of this invention (215 m 2 (420 μmol / g). More importantly, rGO-SiO2 is a synthetically produced spherical particle with discontinuous "dead-end pores" or slit pores inside, lacking the interconnected mesoporous channels characteristic of natural fibrous minerals. Therefore, the diffusion path of the remediation agent in the rGO-SiO2 carrier is longer and the migration resistance is greater, resulting in a much lower release rate and migration efficiency of the remediation agent after photothermal response compared to the present invention.

[0271] In summary, the pH-photothermal dual-response self-healing separation membranes prepared in Examples 1-10 of this invention exhibit high separation efficiency, high rejection rate, and high throughput in the treatment of oily wastewater, dye wastewater, and industrial mixed wastewater. Even after mechanical scratches and alkaline corrosion, they can still achieve efficient in-situ self-healing, with significant recovery of oil separation efficiency, dye rejection rate, and water throughput. This is inseparable from the rod-shaped / fibrous one-dimensional morphology of the carrier silicate mineral, the calcination + acid activation process, the appropriate loading of photothermal materials (5-15 wt%), the efficient hydrophobic anchoring of the repair agent, pH-responsive gated encapsulation, and the synergistic division of labor in the three-layer structure. These factors work in concert as an organic whole, enabling the prepared separation membrane to exhibit excellent separation performance and mechanical scratch and alkaline corrosion repair capabilities when treating oily wastewater, dye wastewater, and industrial mixed wastewater, greatly extending the service life of the separation membrane.

[0272] Example 4: Cyclic Self-Healing Performance Test

[0273] To further verify the stability of the pH-photothermal dual-response self-healing separation membrane of the present invention under different wastewater systems (oil-containing wastewater, dye wastewater, and mixed oil and dye wastewater), taking Example 1 as an example, two types of cycle tests were carried out: mechanical scratch-photothermal repair and alkali corrosion-pH response repair, to examine the separation efficiency / retention rate and flux retention capacity (Table 6).

[0274] 1. Testing Method

[0275] 1) Determine the initial performance under the corresponding wastewater system;

[0276] 2) Cyclic Mode A: Perform 80μm standard mechanical scratches on the membrane surface → irradiate with 808nm laser for 5 minutes for photothermal repair → test performance;

[0277] 3) Cyclic Mode B: Immerse the membrane in a NaOH aqueous solution with a pH of 11 for 2 hours (alkali corrosion) → treat with acetate buffer at a pH of 3.0 for 30 minutes (pH-triggered repair) → test performance;

[0278] 4) Repeat the loop 3 times in sequence;

[0279] 5) Calculate the repair efficiency and flux recovery rate for each cycle.

[0280] 2. Test Results

[0281] Table 6 Dual-Response Cyclic Self-Healing Performance

[0282]

[0283] As shown in Table 6, in Example 1, under both photothermal and pH cycling modes, after three cycles of damage-repair, the oil repair efficiency was ≥95.6%, the dye repair efficiency was ≥93.8%, and the flux recovery rate was ≥91.0% under the photothermal cycling mode; under the pH cycling mode, the oil repair efficiency was ≥92.8%, the dye repair efficiency was ≥91.0%, and the flux recovery rate was ≥85.9%, with no sharp performance degradation. The pH cycling repair efficiency was slightly lower than that of the photothermal cycling, mainly because the Schiff base bonds under strongly alkaline conditions undergo partial irreversible hydrolysis, leading to a gradual decrease in crosslinking density; while the photothermal cycling is a completely reversible process, and the crosslinking network re-densifies after temperature recovery, thus exhibiting better cycling stability.

[0284] The results show that the separation membrane of the present invention has a complete pH-photothermal dual-response gated encapsulation structure, stable controlled release of the remedial agent, and high dual-response cycle reliability. It can operate stably for a long time in complex industrial wastewater environments, significantly extending the membrane's service life.

[0285] The embodiments described above are merely preferred embodiments of the present invention, and not an exhaustive list of all possible implementations of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A pH-photothermal dual-response self-healing separation membrane, characterized in that, It includes, from bottom to top, a support layer, a pH-photothermal dual-response self-healing functional layer, and a superhydrophobic separation functional layer; The pH-photothermal dual-response self-healing functional layer is made of pH-photothermal dual-response self-healing composite material; The pH-photothermal dual-response self-healing composite material is prepared by sequentially activating the carrier, loading the photothermal material, loading the repair agent, and encapsulating the polymer material under pH-responsive gating using rod-shaped or fibrous silicate minerals as a carrier. The pH-responsive gated encapsulation of the polymer material includes the following steps: dispersing the composite material of loaded photothermal material-repair agent obtained after loading the repair agent in acetate buffer, then adding hydrophilic polymer, adding crosslinking agent solution, carrying out crosslinking reaction at 30-50℃, controlling the degree of crosslinking to 50%-80%, centrifuging and drying to obtain pH-photothermal dual-responsive self-healing composite material. The hydrophilic polymer includes one or both of chitosan and carboxymethyl chitosan; The crosslinking agent includes either glutaraldehyde or epichlorohydrin.

2. The pH-photothermal dual-response self-healing separation membrane as described in claim 1, characterized in that, The support layer includes a polytetrafluoroethylene support layer, a polyvinylidene fluoride support layer, a polyester nonwoven fabric support layer, a polypropylene nonwoven fabric support layer, a polyamide support layer, or a nylon mesh support layer. The thickness of the support layer is 100–300 μm; The thickness of the pH-photothermal dual-response self-healing functional layer is 3–20 μm; The thickness of the superhydrophobic separation functional layer is 50–200 μm; The water contact angle of the superhydrophobic separation functional layer is ≥150°.

3. The pH-photothermal dual-response self-healing separation membrane as described in claim 1, characterized in that, The preparation method of the pH-photothermal dual-response self-healing composite material includes the following steps: (1) Activation of the carrier: The rod-shaped or fibrous silicate minerals are calcined at 300-500℃ and activated. After cooling, they are refluxed with 3-8 mol / L hydrochloric acid under stirring. After centrifugation, the solid is collected, washed until neutral, vacuum dried, ground and sieved to obtain the activated carrier. (2) Photothermal material loading: The activated carrier is dispersed in water, and then the photothermal material or photothermal material precursor is added. The pH value is adjusted to 9-11, and the reaction is heated for 4-24 hours to obtain a composite material loaded with photothermal material. (3) Repair agent loading: The composite material loaded with photothermal material is dispersed in ethanol, hydrophobic silane and repair agent are added, and then ultrasonic treatment is performed for 10 to 30 min. Then, it is stirred and adsorbed at 20 to 30 °C for 12 to 24 h. Then, it is centrifuged and dried to obtain the composite material loaded with photothermal material-repair agent. (4) pH-responsive gated encapsulation: The composite material loaded with photothermal material-repair agent is dispersed in acetate buffer, then hydrophilic polymer is added, crosslinking agent solution is added dropwise, crosslinking reaction is carried out at 30-50℃, the degree of crosslinking is controlled at 50%-80%, centrifuged and dried to obtain pH-photothermal dual-responsive self-repairing composite material.

4. The pH-photothermal dual-response self-healing separation membrane as described in claim 3, characterized in that, The carrier activation includes: first calcination activation, then acid activation; The silicate minerals include any one of attapulgite, sepiolite, and halloysite. The photothermal material precursor includes any one of soluble cerium salt and graphene oxide; The photothermal material includes any one of nano-cerium oxide, reduced graphene oxide, carbon nanotubes, and MXene; In the composite material loaded with photothermal material, the loading amount of photothermal material is 5-15 wt%; The repair agent includes one or more of 2-mercaptobenzothiazole, benzotriazole, and 2-mercaptobenzimidazole; The mass concentration of the crosslinking agent solution is 20-30%; The hydrophobic silane includes one or more of perfluorodecyltrimethoxysilane, perfluorooctyltrimethoxysilane, and heptadecafluorodecyltrimethoxysilane.

5. The pH-photothermal dual-response self-healing separation membrane as described in claim 1, characterized in that, The superhydrophobic separation functional layer is prepared by a non-solvent-induced phase separation method using hydrophobic modified silicate minerals and polymers.

6. The pH-photothermal dual-response self-healing separation membrane as described in claim 5, characterized in that, The mass ratio of the hydrophobically modified silicate mineral to the polymer is 1:4 to 6; The hydrophobically modified silicate minerals include any one of hydrophobically modified attapulgite and hydrophobically modified sepiolite. The polymer includes fluoropolymers or polyethersulfone.

7. The method for preparing the pH-photothermal dual-response self-healing separation membrane according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Prepare pH-photothermal dual-response self-healing composite material; Step 2: Preparation of pH-photothermal dual-response self-healing functional layer: The pH-photothermal dual-response self-healing composite material and dispersant are added to the resin material and stirred and dispersed evenly at a temperature of ≤40℃. Then, it is coated on the surface of the support layer, and the dry film thickness is controlled to be 3~20μm. After curing, the pH-photothermal dual-response self-healing functional layer is formed. Step 3: Preparation of superhydrophobic separation functional layer: Dissolve or disperse hydrophobic modified silicate minerals and polymers in a solvent, then add a pore-forming agent, stir evenly, and form a film by non-solvent-induced phase separation method. Then, control the coagulation bath temperature to 10-30℃ and the pH value of the coagulation bath to 6.5-7.5 for coagulation bath solidification to form a superhydrophobic separation functional layer, and obtain a pH-photothermal dual-response self-healing separation membrane.

8. The preparation method according to claim 7, characterized in that, The resin material includes any one of waterborne polyurethane, waterborne acrylic resin, and waterborne epoxy resin; The dispersant includes any one of BYK-190, BYK-163, and DISPERBYK-110.

9. The preparation method according to claim 7, wherein the solvent comprises one or more of N-methylpyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide; The porogen includes one or both of polyvinylpyrrolidone and polyethylene glycol, and the concentration of the porogen is 8-15 wt%.

10. The application of the pH-photothermal dual-response self-healing separation membrane as described in any one of claims 1-6 in the treatment of oily wastewater, dyeing and printing wastewater, or industrial mixed wastewater containing oil and dye.

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