Metal specific adsorption composite membrane as well as preparation method and application thereof

Abstract

The invention relates to a specific composite membrane as well as a preparation method and application thereof, and the preparation method comprises the following steps: preparing a specific adsorption particle solution by adopting a precipitation polymerization method, dissolving the specific adsorption particle solution in a membrane preparation solution, and constructing the composite membrane with dual functions of specific adsorption and filtration by adopting a phase inversion method, a spinning method or a stretching method. According to the composite membrane prepared by the preparation method disclosed by the invention, the specific particles can be distributed on the surface layer of the membrane and can be loaded in the porous layer of the membrane, and the porous layer has more loading capacity than the surface layer, so that the composite membrane has the advantages of high loading capacity of the particles in the membrane and high adsorption capacity of the membrane to target ions. The specific composite membrane can be well suitable for removing and / or detecting ions in the environment, industrial and agricultural wastewater or food.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis and detection, specifically relating to a metal-specific adsorption composite membrane, its preparation method, and its application in the removal and detection of metal ions. Background Technology

[0002] Heavy metal pollution and residues are easily found in the environment, water, and food. Mining, electronics processing, and textile manufacturing, in particular, can easily lead to heavy metal pollution of the surrounding environment and water resources. Factory wastewater discharge also commonly exceeds heavy metal standards. Excessive levels of toxic and harmful heavy metal ions in water, alcohol, fruit and vegetable juices, and other foods pose a threat to food safety. These excessive heavy metals threaten environmental resources, food safety, and public health. Simultaneous removal and detection of toxic and harmful heavy metal ions in the environment, industrial and agricultural wastewater, water resources, and food are of great significance for building a green environment, promoting wastewater utilization, driving energy recycling, and ensuring food safety. Commonly used technologies for removing heavy metal ions from the environment, water, and food include adsorption, precipitation, and chemical reaction methods. Adsorption methods use adsorbents such as activated carbon, bentonite, and ion exchange resins to adsorb heavy metal ions. Precipitation methods add hydroxides and sulfides to form insoluble precipitates (e.g., sulfide precipitation of cadmium and lead). Chemical reaction methods add reducing agents (e.g., for treating hexavalent chromium) or oxidizing agents to break down complex structures, followed by precipitation removal. These methods involve many steps and are quite cumbersome. Moreover, the direct addition of chemicals poses a risk of secondary chemical pollution to the environment and food. Therefore, research on the green removal of heavy metal ions from food is particularly important.

[0003] Membrane separation technology, as a purely physical method, requires no chemical reagents and involves no phase change. Based on the selective permeability and pore size of the membrane, substances of different molecular weights, hydrophilicity / hydrophobicity, and structures can pass through at room temperature without altering their original properties. It has enormous application potential in water treatment and food processing, not only maximally retaining harmful components but also preserving the original nutrients in water and food, making it a safe and green method for water treatment and food processing. Currently, membrane separation technology is widely used for drinking water purification. Using membrane technology to remove highly toxic heavy metals from water resources and food is not only green and safe but also simple, fast, and easy to operate in a continuous industrial cycle, leaving no chemical reagent residues and preserving the original quality of water resources and food to the greatest extent possible.

[0004] Specific adsorption particles have garnered significant attention in the analytical field. When a target analyte comes into contact with a specific adsorption material, it is specifically adsorbed onto the material. Currently, most specific adsorption particles are dispersed in solution, adsorbing the target analyte in liquid form. This method has the following drawbacks: First, it still requires pretreatment and purification steps before detection; second, the adsorption particles need to be thoroughly ground before being added to the solvent, as the adsorption material is prone to aggregation or precipitation in solution, affecting adsorption efficiency and creating a technical bottleneck for detection accuracy; third, aggregation and moisture absorption during storage can affect performance and make preservation difficult; fourth, it is easily affected by interference from other matrices in the sample during actual sample detection; fifth, the adsorption process requires a relatively long time; and sixth, it cannot simultaneously remove and detect heavy metals.

[0005] The detection technologies for heavy metals in the environment, factory wastewater, sewage, and food generally suffer from technical bottlenecks due to cumbersome and time-consuming pretreatment steps, typically requiring high-temperature digestion. To transform environmental and factory wastewater into valuable resources and to ensure food safety from heavy metal contamination, it is necessary to develop green physical technologies that simultaneously remove and detect hazardous heavy metals. This would meet the needs of transforming environmental resources into valuable resources and address the specific safety and quality requirements of food, while avoiding the secondary damage to environmental resources, changes in food flavor and quality, and the risk of secondary pollution from chemical materials that are easily caused by other methods.

[0006] Currently, the preparation of specific adsorption membranes generally uses existing ultrafiltration or microfiltration membranes as base membranes and employs a surface grafting adsorption site method to adsorb grafted adsorption particles onto the surface of the base membrane. This results in the specific adsorption particles being primarily distributed in the surface layer of the base membrane, while the porous layer of the membrane contains almost no specific adsorption particles. This significantly limits the loading of specific particles and affects the adsorption capacity of the specific adsorption membrane for target ions. Existing applications of specific adsorption membranes are mainly concentrated on the adsorption and removal of heavy metals from wastewater. The adsorption and removal of heavy metals from environmental, industrial, agricultural, and water resources, especially the simultaneous removal and detection of heavy metals in the environment and food, has not yet been reported. Summary of the Invention

[0007] Based on this, the purpose of this invention is to provide a metal-specific adsorption composite membrane, its preparation method, and its application in the simultaneous removal and rapid detection of heavy metals. The specific composite membrane has both sample purification and heavy metal-specific adsorption functions, and also has the advantages of more stable adsorption performance, better detection linearity, and strong regenerability.

[0008] The first aspect of this invention is to provide a method for preparing a metal-specific adsorption composite membrane, the method comprising the following steps:

[0009] S1. Preparation of specific adsorbent particles (IIPs) using precipitation polymerization, including:

[0010] S1.1. The metal template ions and functional monomers are fully reacted, and a crosslinking agent and an initiator are added to polymerize the metal template ions and functional monomers to generate a crosslinked polymer. The molar ratio of the heavy metal template ions to the functional monomers is 1:(1-8).

[0011] S1.2 The metal template ions are eluted from the polymer using an eluent to form functional pores that spatially match the metal ions. After drying, the specific metal adsorption particles are obtained.

[0012] S2. Preparation of metal-specific adsorption composite membranes (IIPs@PES) by phase inversion method, spinning method or stretching method, including: S2.1 Dissolving a polymer material substrate and a pore-forming agent in a solvent to obtain a membrane-forming solution, wherein the solvent is N,N-dimethylformamide, N,N-dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP).

[0013] S2.2 Add metal ion specific adsorption particles to the film-forming solution, stir, dissolve, and then add additives to obtain a film casting solution; the additives are sodium dodecyl sulfonate (SDS), isopropanol, propylene glycol, oleic acid, polyvinylpyrrolidone (PVP), ionic liquids, or a mixture thereof.

[0014] S2.3 The membrane casting solution is injected into a metering pump, extruded from the spinneret, passes through an air layer, enters a coagulation bath, solidifies and forms the membrane, then stretches, winds, washes with water at room temperature, dries, and collects it with rollers to obtain a metal-specific hollow fiber membrane; or

[0015] The membrane casting solution is scraped onto the support layer, evaporated, and then immersed in a coagulation bath of deionized water or N,N-dimethylacetamide (DMAC) aqueous solution to obtain a metal-specific adsorption flat sheet membrane.

[0016] In some embodiments, S2.4 is also included. The metal-specific adsorption flat plate membrane and the guide net are alternately stacked, the central tube is spirally wound, and the edges are sealed with resin to obtain the metal-specific adsorption spiral wound membrane.

[0017] The metal-specific adsorption composite membrane of the present invention includes a metal-specific adsorption flat sheet membrane, a metal-specific hollow fiber membrane, and a metal-specific adsorption spiral wound membrane. The specific adsorption function is attributed to the specific adsorption particles, and the filtration function is mainly attributed to the sieving effect of the membrane pores. The combination of the two can achieve a good combination of sample purification and specific adsorption of heavy metal ions. Moreover, the adsorption performance is more stable, the adsorption is faster, and the regenerability is stronger. It can be used as a green, fast, and efficient technology for the removal and detection of heavy metal ions in the environment, wastewater, and food.

[0018] In some embodiments, the specific adsorption particles are copper ion specific adsorption particles, lead ion specific adsorption particles, mercury ion specific adsorption particles, antimony ion specific adsorption particles, nickel ion specific adsorption particles, cadmium ion specific adsorption particles, or other metal specific adsorption particles.

[0019] In some embodiments, the molar ratio of the heavy metal template ion to the functional monomer is 1:(1-8), preferably 1:1-5, and more preferably 1:(2-4).

[0020] In some embodiments, in S1.1, the functional monomer is chitosan, acrylic acid, methacrylic acid, 4-vinylpyridine, vinylimidazole, thiocyanopropyl dimethoxysilane, 3-aminopropyltriethoxysilane, etc.

[0021] In some embodiments, the crosslinking agent in S1.1 is epichlorohydrin, ethylene glycol dimethacrylate, ethylene glycol dimethacrylate, tetraethoxysilane, etc.

[0022] In some embodiments, when the metal template ion in S1.2 is lead ion, the eluent is nitric acid, the functional monomer is methacrylic acid, and the crosslinking agent is ethylene glycol dimethacrylate.

[0023] In some embodiments, when the metal template ion in S1.2 is antimony ion, the eluent is hydrochloric acid, which functions as the monomer thiocyanopropyl dimethoxysilane, and the crosslinking agent is cyclochloropropane.

[0024] In some embodiments, when the metal template ion in S1.2 is a copper ion, the eluent is hydrochloric acid, the functional monomer is 3-aminopropyltriethoxysilane, and the crosslinking agent is tetraethoxysilane.

[0025] In some embodiments, the support layer is made of nonwoven fabric, glass fiber, polyester, chlorofiber, nylon, or porous nylon.

[0026] In some embodiments, the evaporation time in S2.3 is 5-60 seconds, preferably 10-40 seconds, and more preferably 15-30 seconds.

[0027] In some embodiments, the percentage weight ratio of the polymer material substrate and the pore-forming agent in the film casting solution is 5-40% and 1-10%, respectively, preferably 10±20% for the polymer material substrate; or preferably 2±1% for the pore-forming agent.

[0028] In some embodiments, the additive is sodium dodecyl sulfonate (SDS), isopropanol, propylene glycol, oleic acid, polyvinylpyrrolidone (PVP), ionic liquids, or a combination thereof.

[0029] Preferably, the additive is a mixture of polyvinylpyrrolidone and oleic acid, more preferably a PVP to oleic acid mass ratio of 3-5:1.

[0030] Preferably, the additive is a mixture of polyvinylpyrrolidone and isopropanol, more preferably a PVP to isopropanol mass ratio of 1-2:1.

[0031] And / or the mass ratio of the additive to the film-forming solution is 1:(5-30), preferably 1:(10-20).

[0032] In some embodiments, the ratio of the metal-specific adsorbent particles to the film casting solution is (5-100) mg: 15 ml; preferably (30-50) mg: 15 ml, more preferably (40-50) mg: 15 ml.

[0033] In some embodiments, a suitable polymeric material substrate is selected based on the hydrophilicity or oleophilicity of the system from which the metal is removed or detected. When the test system is aqueous, hydrophilic materials such as polyvinylidene fluoride (PVDF), polyethersulfone (PES), polysulfone (PS), and polyvinyl chloride (PVC) are selected; when the test system is hydrophobic, hydrophobic materials such as polytetrafluoroethylene (PTFE), polypropylene (PP), and polyethylene (PE) are selected.

[0034] In some embodiments, the porogen in S2.2 is a polyvinylpyrrolidone or other porogen such as polyethylene glycol.

[0035] A second aspect of the present invention is to provide a metal-specific adsorption composite membrane obtained by any of the above preparation methods.

[0036] A third aspect of the present invention is to provide the application of any of the metal-specific adsorption composite membranes described herein in the removal and / or detection of metal ions in the environment, wastewater, or food, etc.

[0037] In some embodiments, the metal ions include lead ions, mercury ions, antimony ions, nickel ions, zinc ions, cadmium ions, etc. In some preferred embodiments, the metal ions are toxic and harmful heavy metals, including lead ions, mercury ions, antimony ions, nickel ions, cadmium ions, etc.

[0038] In some implementations, the environment and water include water resources surrounding mineral development, coal mining, electronics processing, textile manufacturing, etc., factory wastewater, tap water, drinking water, agricultural wastewater, natural lakes, well water, or other water that requires the removal of heavy metal ions.

[0039] The food items include alcohol, fruit and vegetable juices and other beverages, soy sauce, vinegar, milk, etc.

[0040] This invention involves dissolving a solution of specific metal adsorption particles prepared by precipitation polymerization in a membrane-forming solution. A metal-specific adsorption composite membrane with dual functions of specific adsorption and filtration is then constructed using phase inversion, spinning, or stretching methods. The preparation method employed in this invention allows the specific adsorption particles to be distributed not only on the surface layer of the membrane but also loaded into the porous layer, which has a higher loading capacity than the surface layer. This results in a high loading capacity of specific adsorption particles and a high adsorption capacity for target ions. The specific adsorption particles in the composite membrane can fully bind to the ions to be removed or detected, achieving a highly specific adsorption effect for target ions. The porous structure of the composite membrane can filter out interfering components in the sample, thereby achieving sample purification.

[0041] The specific composite membrane prepared according to the present invention has the following advantages:

[0042] 1. Due to the stable performance of the specific adsorption particles after loading into the membrane, it can be applied with high specificity and high sensitivity to remove or detect heavy metals such as lead ions, mercury ions, antimony ions, nickel ions, and cadmium ions. It integrates sample pretreatment and specific adsorption of heavy metal ions, and the entire adsorption or detection process is completed within 30 minutes.

[0043] 2. Because the specific adsorption particles are loaded in a solid membrane, it overcomes the technical bottlenecks caused by the aggregation and precipitation of particles in liquid form, which leads to incomplete adsorption, difficulty in elution and collection, and excessively long adsorption saturation time. In addition, the specific composite membrane also has a purification function, so no sample pretreatment is required. The cyclic adsorption and enrichment of the specific adsorption particles in the specific composite membrane makes the adsorption more efficient and complete, and simpler and faster for detection.

[0044] 3. The preparation method of the specific composite membrane does not require complex pretreatment, and has the advantages of being simple to operate, portable, easy to store and transport, and suitable for on-site removal and rapid detection. It can achieve specific adsorption and removal and accurate quantification of heavy metals such as lead ions, mercury ions, antimony ions, nickel ions, and cadmium ions in actual samples.

[0045] 4. After the specific composite membrane is eluted with a suitable solvent, the adsorbed metal will be detached from the membrane, and the adsorption sites will be exposed again, allowing for recycling and cost savings;

[0046] 5. The adsorption membrane, being in solid form, is easy to store and transport, and has a long shelf life. Attached Figure Description

[0047] Figure 1 Electron micrographs of PES and IIPs@PES films are shown. (a, b, c) show Pb in the PES and IIPs@PES films, respectively.2+ Surface electron microscopy images of ion-specific adsorption particles (IIPs) with added amounts of 50 mg and 60 mg. (d, e, f) are cross-sectional electron microscopy images of PES membranes with added amounts of IIPs@PES membranes of 50 mg and 60 mg.

[0048] Figure 2 For PES membrane, Sb 3+ Surface and cross-sectional electron micrographs of IIPs@PES films, a, b are without Sb. 3+ PES membrane with specifically adsorbed particles (IIPs), a is the surface of the membrane, b is the cross-section of the membrane; c and d are Sb 3+ IIPs@PES membrane with a specific adsorption particle (IIPs) addition of 40 mg, where c is the surface of the membrane and d is the cross section of the membrane.

[0049] Figure 3 For IIPs particles, PES membranes and Sb 3+ Infrared spectrum of IIPs@PES membrane with 40 mg of ion-containing IIPs particles.

[0050] Figure 4 (a) is Sb 3+ Stability of specific membranes IIPs@PES. (b) Sb 3+ Regenerability of specific membranes IIPs@PES.

[0051] Figure 5 For Sb 3+ The IIPs@PES membrane, under the coexistence of other interfering ion concentrations, exhibits good performance regarding Sb. 3+ The adsorption rate. Detailed Implementation

[0052] To facilitate understanding of the present invention, a more complete description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0053] Unless otherwise specified, experimental methods in the following examples are generally performed under standard conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the examples are commercially available products.

[0054] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0055] To facilitate understanding of this technology, some terms and phrases are defined below.

[0056] PES: Polyethersulfone.

[0057] PS: Polysulfone.

[0058] PVC: Polyvinyl chloride.

[0059] PTFE: Polytetrafluoroethylene.

[0060] PEG: Polyethylene glycol.

[0061] DMF: N,N-dimethylformamide.

[0062] DMAC: N,N-dimethylacetamide.

[0063] PVP: Polyvinylpyrrolidone; SDS: Sodium dodecyl sulfonate.

[0064] High-purity water is water with extremely high chemical purity, and its core indicators include:

[0065] Conductivity: less than 0.1 μS / cm (25℃), indicating that the conductive medium (such as ions) has been almost completely removed.

[0066] Salt content: less than 0.3 mg / L, and total impurities controlled below 0.1 mg / L.

[0067] Other characteristics: The pH value is stable between 6.8 and 7.0, and non-electrolytes such as colloids, organic matter and microorganisms have been removed.

[0068] In this article, specific composite membranes, metal-specific adsorption flat sheet membranes, metal-specific hollow fiber membranes, metal-specific adsorption spiral wound membranes, composite membranes, and Pb are mentioned. 2+ Composite membrane, IIPs@PES membrane, Sb 3+ Specific composite film, Cu 2+ Specific membrane, Cu 2+ Specific adsorption hollow fiber membranes (IIPs@PS) and others all share the same name: metal-specific adsorption composite membranes.

[0069] A specific composite membrane is prepared by loading specific metal adsorption particles onto a solid membrane to form a specific metal adsorption membrane (hereinafter also referred to as a composite membrane). The green adsorption removal and detection method using the composite membrane prepared in this invention reduces the complex pretreatment process in existing methods, has good filtration performance and specific adsorption function, and integrates sample pretreatment and specific adsorption of heavy metal ions into one process. It avoids particle aggregation, enables the enrichment, removal, and detection of trace substances in a large number of samples, improves detection accuracy, and significantly lowers the detection limit. Simultaneously, the adsorption sites in the composite membrane can specifically adsorb and identify target analytes, and the porous structure of the composite membrane can filter and remove other interfering components in environmental, wastewater, food, and other matrices, thereby improving sensitivity and adsorption capacity. The composite membrane specifically adsorbs lead ions in environmental, wastewater, food, and other matrices. After targeting heavy metals such as lead, cadmium, copper, antimony, mercury, and manganese ions, the composite membrane can remove toxic and harmful heavy metals from food, meeting the limits for heavy metal ion content in the environment, wastewater, and food. After the composite membrane specifically adsorbs target heavy metals such as lead, cadmium, copper, antimony, mercury, and manganese ions from the environment, industrial and agricultural wastewater, and food, the adsorbed metal ions are eluted from the composite membrane using a suitable elution solvent. Quantification is then performed using atomic absorption spectrophotometry, ion chromatography-inductively coupled plasma chromatography, or ion chromatography-mass spectrometry, enabling precise detection of toxic and harmful heavy metals in the environment, wastewater and water resources, and food. This method is convenient, rapid, highly specific, low-cost, and simple to operate, providing a new strategy for the removal of harmful substances from the environment and food, as well as rapid detection of food safety issues, and has practical application value.

[0070] The present invention will be further described in detail below with reference to specific embodiments.

[0071] Example 1

[0072] This embodiment discloses Pb 2+ The preparation method of the composite membrane and its application in the rapid removal and determination of lead ions in water, liquor, and other food products includes the following steps:

[0073] (1) Preparation of Pb 2+ Specific adsorbent particles (IIPs): prepared by precipitation polymerization.

[0074] S1.1. Take 1 mmol of Pb(NO3)2 into a 25 mL test tube, add 10 mL of a 1:1 mixture of DMF and chloroform, dissolve, and then add 4 mmol of the functional monomer methacrylic acid (MAA). Shake for 3 h to allow the reaction to proceed. Then, add 20 mmol of the crosslinking agent ethylene glycol dimethacrylate and 50 mg of the initiator azobisisobutyronitrile (AIBN) in sequence. Sonicate for 5 min, purge with nitrogen for 10 min to remove air, and immediately seal the test tube. React in a 60 °C water bath for 24 h to fully polymerize and form a lead-adsorbed polymer.

[0075] S1.2 The formed polymer was dissolved in an ethanol solution for 24 hours, then washed several times with 2 mol / L nitric acid solution until no lead ions were detected in the eluent. Finally, it was washed with high-purity water until neutral and dried in a drying oven. In the preparation of specific adsorbent particles, the functional template, crosslinking agent, and parameters such as dosage and ratio were all optimized experimentally.

[0076] The functional monomer of this invention was experimentally optimized to be methacrylic acid, which can both interact with the adsorbent molecules and be positioned appropriately with the crosslinking agent molecules to achieve the desired orientation and localization of the adsorption target. Our study found that, under otherwise comparable conditions, when other functional monomers such as 4-vinylpyridine (4-VP), acrylamide (AM), and chitosan were used, the prepared specific adsorbent particles (IIPs) did not show significant adsorption of lead ions. See Table 1 below.

[0077] Table 1

[0078]

[0079] Selection of crosslinking agent: In this invention, the lead-specific adsorbent particles are crosslinked by ethylene glycol dimethacrylate and the functional monomer methacrylic acid, which undergo a polymerization and crosslinking reaction to generate chemical bonds that link the linear molecules together, thereby forming a network structure. Under the same conditions, when other crosslinking agents such as divinylbenzene (DVB), dimethyl vinyl diisocyanate (TMIC), and trimethylethanol hydroxypropyl methacrylamide (TRIM) are selected, the synthesized lead-specific adsorbent particles do not show significant adsorption of lead ions.

[0080] Selection of eluent: In this example, Pb 2+ In the preparation of specific adsorption particles, nitric acid is chosen as the eluent because it must fully elute the template from the particles to obtain adsorption sites without damaging the particle structure. When other eluents are used, such as hydrochloric acid, sodium chloride, potassium chloride, ethylenediaminetetraacetic acid, or carboxymethyl-β-cyclodextrin, either the template elution may be insufficient, or the eluent may damage the particle structure, resulting in the eluted particles having virtually no adsorption capacity for lead ions.

[0081] The ratio of template molecules to functional monomers has a significant impact on polymer morphology, size, and effective adsorption sites. When the ratio is too small, the number of recognition sites decreases, leading to low lead ion adsorption efficiency; when the ratio is too large, excess template molecules undergo self-polymerization, similarly reducing effective adsorption sites and resulting in low lead ion adsorption rate. The optimal molar ratio of lead nitrate to methacrylic acid, after experimental optimization, is 1:1-5; in this example, the optimal ratio is 1:4.

[0082] The ratio of template molecules to crosslinking agent: If the crosslinking agent is too small, it is difficult to form a polymer or the formed network polymer is unstable, resulting in the destruction of adsorption sites and low adsorption efficiency; if the crosslinking agent is too large, the adsorption layer of the particles is too thick, the specific adsorption sites are not easily exposed, and the overly dense adsorption layer makes template elution difficult, which also leads to low adsorption efficiency. Through experimental exploration, the optimized ratio of template molecule lead acetate to crosslinking agent ethylene glycol dimethacrylate is preferably 1:10-30. In this embodiment, the optimal ratio for preparing lead-specific adsorption particles is 1:20.

[0083] Furthermore, we found that the precipitation polymerization method for preparing specific adsorbent particles offers higher controllability of product morphology compared to other methods such as bulk polymerization and sol-gel methods. This helps improve the stability, uniformity, and selectivity of the adsorbent particles, facilitating the subsequent preparation of more uniform and controllable specific membranes and providing a foundation for precise adsorption localization. Moreover, this method is simple to operate and has low cost, making it suitable for industrial production.

[0084] (2) Preparation of specific composite membranes (IIPs@PES) by phase inversion method, spinning method or stretching method.

[0085] Methods for preparing specific composite membranes include phase inversion, spinning or stretching, in-situ polymerization, membrane surface grafting, and membrane coating. Regarding the aforementioned specific in-phase adsorption particles (IIPs), we found that when using methods such as in-situ polymerization and membrane surface grafting, the adsorbed IIPs are primarily distributed on the surface layer of the membrane, while the porous and support layers are largely devoid of adsorbed particles. This results in a low IIP particle loading in the specific adsorption membrane and a low lead ion adsorption rate.

[0086] In this embodiment, IIPs@PES membranes were prepared using the phase inversion method.

[0087] S2.1 PES, PEG400 or PEG800 are added to DMF to form a film-forming solution. The percentages of polymer, pore-forming agent and solvent in the film-forming solution are: PES (10%, by weight of solution), PEG400 or PEG800 (2%). The solution is stirred vigorously at 50°C for 2 hours to dissolve.

[0088] S2.2 Add Pb 2+Adsorbed particles (IIPs:film-forming solution = 5-60 mg / 15 ml) were prepared. Then, a mixture of polyvinylpyrrolidone (PVP):oleic acid (mass ratio PVP:oleic acid = 4:1) was added as an additive (additive:film-forming solution = 1:10). The mixture was then vigorously stirred at 50°C for 30 minutes to dissolve. The film-forming solution was scraped onto a nonwoven fabric on a glass plate using a doctor blade, evaporated for 15 seconds, and then immersed in a deionized water coagulation bath to obtain the IIPs@PES membrane.

[0089] The method and process for preparing PES membranes are the same as those for preparing IIPs@PES membranes, except that IIPs particles are not added.

[0090] In the preparation of IIPs@PES membranes, the uniform dispersion of adsorbed particles in the membrane-forming solution affects the dispersion uniformity of IIPs in the membrane, and the binding of adsorbed particles with the membrane-forming solution also affects the membrane performance. Experiments have shown that directly mixing IIPs particles with the polymer membrane-forming solution system easily leads to severe particle aggregation, and the prepared composite membrane is prone to structural defects. Therefore, through experimental optimization, mixing IIPs particles with the membrane-forming solution system first, followed by the addition of suitable additives, not only effectively avoids the generation of structural defects in the composite membrane, but also ensures uniform particle dispersion and excellent membrane structural performance.

[0091] The ratio of the polymeric membrane substrate PES and the pore-forming agent PEG in the film-forming solution, as well as the evaporation time, all affect the pore size and thickness of the IIPs@PES membrane. After experimental optimization, the optimal addition amount of IIPs was 50 mg. Under the conditions of a 10% PES and 2% PEG ratio in the above polymeric mixture (membrane casting solution) and an evaporation time of 15 s, the IIPs@PES membranes prepared according to the optimal conditions of this embodiment (which are also used in the following experiments) had a bubble point pressure of 6.0195 bar, a maximum pore size of 116 nm, and an average pore size of 47.8 nm. In water and food matrices, Pb... 2+ It has the best effect in the detection and removal of ions.

[0092] Table 2. Effects of PEG content of 2% in polymer film-forming mixtures on tap water under different PES ratios.

[0093] Pb 2+ Recovery and removal rates (Pb) 2+ (Addition amount 1000μg / L)

[0094]

[0095] To obtain Pb 2+IIPs@PES membranes exhibit high adsorption rates and excellent membrane performance. The effects of IIPs particle addition levels (20-60 mg) on ​​membrane performance and Pb adsorption were investigated. 2+ The effect of adsorption. In this embodiment, when the PES content is 10%, the IIPs@PES membrane has an effect on the adsorption of Pb in tap water. 2+ The recovery and removal rates are the best.

[0096] (3) Scanning electron microscope

[0097] Scanning electron microscope images of IIPs particles and IIPs@PES films are shown below. Figure 1 As shown.

[0098] The IIPs particles were added at a concentration of 50 mg and 60 mg. The scanning electron microscope image of the specific membrane surface is shown below. Figure 1 As shown in (b) and 1(c), the scanning electron microscope images of the cross-section are as follows: Figure 1 As shown in (e) and 1(f), the surface and cross-sectional scanning electron microscope (SEM) images of the PES film are as follows. Figure 1 As shown in (a) and 1(d). From Figure 1 It is evident that when the amount of IIPs particles added increases to 60 mg, defects begin to appear in the surface structure of the membrane, and the particles agglomerate on the membrane surface. The preferred amount of IIPs added in 5 mL of DMF is 20-50 mg. Therefore, in the preparation of the IIPs@PES membrane in this embodiment, the optimal amount of IIPs added is 50 mg.

[0099] When the amount of IIPs particles added is 50 mg, the IIPs-specific adsorption particles are relatively uniformly distributed on the surface and cross-section of the specific membrane. When the ions to be removed, enriched, or detected pass through the specific membrane with the sample, the composite membrane will specifically recognize and adsorb the ions to be removed, enriched, or detected due to the presence of the IIPs-specific particles, while interfering components in the sample matrix will be filtered out by the filtration and purification effect of the membrane pores of the specific membrane.

[0100] (4) Pb in actual samples 2+ Applications of removal:

[0101] ① One-step green physical removal method, faster and safer

[0102] Add 10 ppb and 1000 ppb of Pb to ultrapure water, mineral water, and baijiu (Chinese liquor), respectively. 2+ The sample is circulated through an IIPs@PES membrane at a pressure of 0.2 MPa, and the IIPs@PES membrane is placed in a membrane fabrication device. This allows for the extraction of Pb from food. 2+ Purely green physical removal; simple, fast, green, and effective.

[0103] ②Pb removal from industrial wastewater by composite membrane 2+ Meets limited requirements

[0104] Three wastewater samples from industrial and agricultural production plants were collected. After membrane purification, lead ions were removed using an IIPs@PES membrane. The Pb content in the wastewater passing through the IIPs@PES membrane was determined by atomic absorption spectrometry, as shown in Table 3. 2+ The content is lower than the limit of Pb in GB 39731-2020 Standard for Discharge of Water Pollutants from Electronic Industry. 2+ The limit requirement of 0.2 mg / L, and the Pb content in GB 5084-2021 Standard for Irrigation Water Quality 2+ The limit requirement is 0.2 mg / L. The water after removal meets the discharge standards and can be used for farmland irrigation.

[0105] Table 3 Pb in actual samples 2+ removal

[0106]

[0107] Note: ND in the table indicates not detected.

[0108] ③ Pb in water and wine after removal by composite membrane 2+ Meets limited requirements

[0109] Water and wine that have passed through the IIPs@PES membrane were analyzed by atomic absorption spectrometry, as shown in Table 4. The Pb content in the samples was... 2+ The content is lower than the limits for contaminants in food specified in GB2762-2022, including Pb. 2+ The limit for bottled drinking water is 0.01 mg / L, and the limit for baijiu (Chinese liquor) and huangjiu (yellow wine) is 0.5 mg / kg.

[0110] Table 4 Pb in actual samples 2+ removal

[0111]

[0112] (5) Pb in actual samples 2+ Applications of the test:

[0113] ① No pre-processing required, faster and simpler

[0114] The existing GB 5009.12-2023 National Food Safety Standard "Determination of Lead in Food" requires a complex pre-digestion process, such as wet digestion, microwave digestion, or pressure vessel digestion. Taking wet digestion as an example, 0.2 g to 3 g of solid sample (accurate to 0.001 g) or 0.50 mL to 5.00 mL of liquid sample needs to be weighed into a graduated digestion tube. For samples containing ethanol or carbon dioxide, the ethanol or carbon dioxide is first removed by heating at low temperature on a hot plate. Then, 10 mL of nitric acid and 0.5 mL of perchloric acid are added, along with a few glass beads. The digestion is then carried out on an adjustable electric furnace (reference conditions: 120 ℃ / 0.5 h to 1 h; increase to 180 ℃ / 2 h to 4 h, increase to 200 ℃ to 220 ℃). If the digestion solution is brownish-red, add a small amount of nitric acid and digest until white fumes are emitted. The digestion solution should then be colorless and transparent or slightly yellow. Remove the acid until nearly dry, stop digestion, cool, and then dilute with water to 10 mL or 25 mL. Mix well and set aside. In practical sample detection applications, the liquid form of IIPs (specifically adsorbed particles) also requires a very complex pretreatment process.

[0115] The IIPs@PES membrane prepared by the method of this invention has advantages due to the presence of pores in the skin layer and filter layer of the membrane.

[0116] The IIPs@PES membrane possesses a purification function, eliminating the need for cumbersome pretreatment and purification steps in practical sample detection. Liquid samples can be directly adsorbed onto the membrane using a constant flow pump through repeated adsorption to achieve Pb detection. 2+ After complete adsorption, elution with HNO3, and dilution with pure water, the sample can be injected for analysis. The entire pretreatment process involves only two steps: adsorption and elution of the IIPs@PES membrane, reducing the number of steps and making it simple and convenient.

[0117] ② The method is more precise and the detection limit is lower.

[0118] Pb prepared by the method of the present invention 2+ Specific IIPs@PES membrane pretreatment detection method: Different concentrations of Pb were added to water and liquor respectively. 2+ Standard solution. After adsorption through an IIPs@PES membrane, elution with HNO3, and dilution of the eluent, Pb was determined by atomic absorption spectrophotometry. 2+ Concentration. The recovery rates of the IIPs@PES membrane method were obtained, as shown in Table 5.

[0119] Table 5 Pb in actual samples 2+ Spiked recovery of the sample (μg / L)

[0120]

[0121] Example 2

[0122] This embodiment discloses Sb3+ Preparation of specific composite membranes and their application in environmental and water environments with Sb 3+ For applications in rapid removal and determination, the preparation method includes the following steps:

[0123] (1) Preparation of Sb 3+ Specific adsorbent particles (IIPs): prepared by precipitation polymerization.

[0124] S1.1 Weigh 1.9200g of SbCl3 and place it in a 150.00mL flask. Add 80.00mL of methanol and heat in a 50℃ water bath until completely dissolved. Then add 4.00mL of the functional monomer thiocyanopropyl dimethoxysilane and react for 2 hours. Reflux for 20 hours, then add 3.00mL of the crosslinking agent cyclochloropropane. Heat and stir in a 50℃ water bath for 4 hours to generate the polymer. S1.2 Extract the generated polymer in ethanol using a Soxhlet extractor for 24 hours, then wash repeatedly with 1mol / L hydrochloric acid solution until Sb is no longer detectable in the eluent. 3+ Finally, wash with high-purity water until neutral, and dry in a drying oven.

[0125] (2) Preparation of specific composite membranes (IIPs@PES) by phase inversion method.

[0126] S2.1 IIPs@PES membranes were prepared using a phase inversion method. PES, PEG400, or PEG800 were added to DMF to form a membrane-forming solution. The percentages of polymers, pore-forming agents, and solvents in the membrane-forming solution were: PES (15%, by weight), PEG400 (2%), and DMF (83%). The solution was stirred vigorously at 50°C for 2 hours to dissolve. S2.2 Adsorbent particles (IIPs: membrane-forming solution = 20-60 mg / 15 ml) were added. Then, a mixture of polyvinylpyrrolidone (PVP):isopropanol (mass ratio PVP:isopropanol = 1:1) was added as an additive (additive: membrane-forming solution = 1:20). The solution was stirred vigorously again at 50°C for 30 minutes to dissolve, yielding the membrane casting solution. The membrane casting solution is scraped onto a nonwoven fabric on a glass plate using a doctor blade, then evaporated for 15 seconds, and then immersed in a deionized water coagulation bath containing DAMC solvent to obtain a metal-specific adsorption flat sheet membrane; S2.4 The specific flat sheet membrane and the flow guide mesh are alternately stacked, the central tube is spirally wound, and the edges are sealed with resin to prepare a specific spiral wound membrane. The method and process for PES membrane are the same as those for IIPs@PES membrane, except that no specific particles are added.

[0127] (3) Performance

[0128] ① Scanning electron microscope

[0129] Sb 3+ Scanning electron microscope image of IIPs@PES membrane as shown below Figure 2 As shown.

[0130] The surface and cross-sectional scanning electron microscope images of the specific composite film are shown below. Figure 2 As shown in (b) and (d), the surface and cross-section of the PES film are obtained using scanning electron microscopy. Figure 2 As shown in (a) and (c).

[0131] from Figure 2 It can be seen that Sb 3+ When the IIPs granule dosage is 40mg, Sb 3+ IIPs-specific particles are relatively uniformly distributed on the surface and cross-section of the specific composite membrane. When antimony ions pass through the specific composite membrane with the sample, the presence of IIPs-specific particles in the composite membrane specifically recognizes and adsorbs Sb. 3+ Interfering components in the sample matrix will be filtered out by the filtration and purification effect of the composite membrane pores.

[0132] The infrared spectrum of the composite membrane is as follows Figure 3 As shown. Specific composite membranes and IIPs particles at 1500 cm⁻¹ -1 and 580 cm -1 The presence of CO, C=O, OC, and CH on both sides indicates successful loading of particles into the membrane. In the film-forming solution, the lone pair electrons of the group transitions in the IIPs particles are weakened by protonation, resulting in an increased energy level difference and a blue shift in the infrared absorption peak. Furthermore, due to the change in the molecular aggregation state of the IIPs particles, the material dispersion is improved, the intermolecular interactions are weakened, and the vibrational frequency increases, leading to a blue shift in some infrared spectra of the IIPs@PES membrane.

[0133] ②Stability and regenerability

[0134] The stability and regeneration performance of the IIPs@PES membrane were investigated. In the stability test, the IIPs@PES membrane was stored in pure water for 30 days, and the adsorption capacity was measured every 5 days. Figure 4 As shown in (a), the IIPs@PES membrane is used to treat Sb. 3+ The adsorption rate (A%) remained above 88.40% after 30 days, showing no significant change.

[0135] In the experiment evaluating the regeneration performance of the IIPs@PES membrane, the adsorption-desorption cycle of the IIPs@PES membrane was repeated 8 times. Figure 4 As shown in (b). After 8 adsorption-desorption cycles, the composite membrane exhibits improved adhesion to Sb. 3+ The adsorption rate is still higher than 87.20%, indicating that the composite membrane has excellent regeneration performance.

[0136] ③IIPs@PES membrane for Sb 3+ Specificity

[0137] IIPs@PES membrane for Sb 3+ Specific adsorption interference experiments such as Figure 5 As shown, common coexisting or foreign metal ions in food, such as Cu, were studied. 2+ Ni 2+ Fe 3+ Ca 2+ Al 3+ Mg 2+ Ba 2+ Na + K + Membrane selectivity. IIPs@PES membrane for Sb 3+ The specific adsorption effect of this ion is significantly higher than that of other ions, indicating that it has a higher specific adsorption effect on Sb. 3+ It is specific. Sb 3+ The thiol groups at the IIP adsorption sites have strong coordination bonds and match the spatial structure of the adsorption pores. Therefore, their effective binding can inhibit the adsorption of other interfering ions by the IIPs@PES membrane. (4) Sb in the sample 3+ Applications of removal:

[0138] ① Sb removal in water after composite membrane 3+ Meets limited requirements

[0139] Add 100 ppb of Sb to a pure aqueous solution 3+ The sample only needs to be repeatedly circulated through the IIPs@PES membrane at a pressure of 0.20 MPa for 2 hours to allow Sb in the permeate liquid to pass through. 3+ ≤5ppb, meeting the GB 5749-2022 "Standards for Drinking Water Quality" for Sb in water. 3+ The requirement of ≤0.005 mg / L is sufficient to control Sb levels in food. 3+ Purely green physical removal: IIPs@PES membrane one-step green physical removal method, faster and safer. See Table 6.

[0140] Table 6. Effects of IIPs@PES membrane with 40 mg of IIPs on Sb in actual samples. 3+ removal

[0141]

[0142] Note: ND in the table indicates not detected.

[0143] ② Sb removal in industrial wastewater after composite membrane removal 3+ Meets limited requirements

[0144] Wastewater from the primary and secondary sedimentation tanks of a factory was collected and subjected to Sb treatment using the specific IIPs@PES membrane prepared by the method of this invention.3+ The removal of Sb in wastewater was achieved after adsorption by an IIPs@PES membrane for 30 minutes. 3+ The concentrations were 0.012 mg / L and 0.005 mg / L, respectively, as shown in Table 7. These concentrations are lower than those specified in GB4287-2012 for total Sb in newly established enterprises. 3+ The emission concentration limit of 0.1 mg / L meets the emission standards.

[0145] Table 7. Effects of IIPs@PES membrane on Sb in wastewater from a dyeing and printing factory. 3+ removal

[0146]

[0147] (5) Sb in the sample 3+ Applications in detection:

[0148] ① No pre-processing required, faster and simpler

[0149] The existing GB5009.137—2025 standard, "National Food Safety Standard - Determination of Antimony in Food," requires a complex pre-digestion process, such as wet digestion, microwave digestion, or pressure vessel digestion. Taking wet digestion as an example, it requires weighing 0.25 g to 3 g of solid sample (accurate to 0.001 g) or accurately transferring 1.00 mL to 5.00 mL of liquid sample. For samples containing ethanol or carbon dioxide, first heat on a hot plate at low temperature to remove the ethanol or carbon dioxide. Add 5-10 mL of a nitric acid-perchloric acid mixture (10+1) and soak for 1 hour or overnight. Then heat on a hot plate to digest. If the solution is dark in color during digestion, add a small amount of nitric acid after it cools slightly and continue digestion until white fumes are emitted and the digestate is colorless and transparent or slightly yellow. Continue heating to remove the acid down to 0.5-1 mL. After cooling, transfer the solution to a 25 mL container and rinse the container several times with a small amount of water. After all the solution has been transferred, add 2.5 mL of hydrochloric acid solution and 2.5 mL of thiourea-potassium iodide solution or thiourea-ascorbic acid solution. Dilute with water to a final volume of 25 mL, shake well, and let stand for 1 hour before measurement. The use of IIPs in specific particulate liquid form in actual sample detection also requires a very complex pretreatment process.

[0150] The IIPs@PES membrane prepared by the method of this invention has advantages due to the presence of pores in the skin layer and filter layer of the membrane.

[0151] The IIPs@PES membrane possesses a purification function, eliminating the need for cumbersome pretreatment and purification steps in practical sample detection. Liquid samples can be directly adsorbed onto the membrane using a constant flow pump through repeated adsorption to achieve Sb removal. 3+After complete adsorption and elution with HCl for 30 minutes, the sample can be injected for analysis. The entire pretreatment process involves only two steps: adsorption and elution of the IIPs@PES membrane, reducing reagent usage and making it simple and environmentally friendly.

[0152] ② The method is more precise and the detection limit is lower.

[0153] The specific IIPs@PES membrane pretreatment detection method prepared by the method of the present invention involves adding 50 ppb and 100 ppb of Sb to a blank water sample, respectively. 3+ Standard solution. After adsorption onto an IIPs@PES membrane for 2 hours, elution with HCl was performed, and the Sb content of the eluent was determined by atomic absorption spectrophotometry. 3+ The concentration was determined, and the recovery rate of the IIPs@PES membrane method was obtained, as shown in Table 8.

[0154] Table 8. Sb in water 3+ Spiked recovery of the sample (μg / L)

[0155]

[0156] Example 3

[0157] This embodiment discloses Cu 2+ Preparation of specific membranes and their application in Cu production wastewater 2+ For applications in rapid removal and determination, the preparation method includes the following steps:

[0158] (1) Preparation of Cu 2+ Specific adsorbent particles (IIPs):

[0159] S1.1. Mix 0.25 g of copper chloride with 60 mL of methanol, add 1.5 mL of the functional monomer 3-aminopropyltriethoxysilane, and react in a 60°C water bath for 1 h. Then add 0.7 mL of tetraethoxysilane (TEOS) and 1.4 mL of ammonia water sequentially, and react at 60°C for 24 h to generate a polymer.

[0160] The S1.2 polymer was eluted sequentially with methanol and water, then Soxhlet extracted in ethanol for 24 h, followed by repeated washing with 1 mol / L hydrochloric acid solution until Cu was not detected in the eluent. 2+ Finally, the particles are washed with high-purity water until neutral to form spatially matching pores for metal ions. After drying in a drying oven, the metal ion-specific adsorbent particles are obtained.

[0161] (2) Preparation of Cu 2+ Specific adsorption hollow fiber membrane (IIPs@PS).

[0162] Cu prepared by spinning method 2+ Specific adsorption hollow fiber membrane IIPs@PS.

[0163] S2.1 PS and PEG400 were added to DMAC to form a film-forming solution. The percentages of polymers, pore-forming agents, and solvents in the film-forming solution were: PS (15%, by weight of solution) and PEG (3%). The solution was stirred vigorously at 50°C for 2 hours to dissolve. Adsorbent particles IIPs (particles: film-forming solution = 30 mg / 15 ml) were added. Then, isopropanol was added as an additive (mass ratio of additive: film-forming solution = 1:20), and the solution was stirred vigorously at 50°C again for 30 minutes to dissolve, thus obtaining the film casting solution.

[0164] S2.2. The film casting solution system is injected into a metering pump under a pressure of 0.3 MPa, extruded from the spinneret, and after passing through an air layer, enters a coagulation bath for curing. After curing and shaping, it is stretched, wound, washed with water at room temperature, dried, and collected by rollers to obtain polysulfone Cu. 2+ Specific adsorption hollow fiber membrane.

[0165] (3) Cu in production wastewater 2+ Applications in removal and detection

[0166] ①Cu in production wastewater 2+ removal

[0167] Wastewater samples were taken from two chemical plants and processed using the polysulfone Cu prepared in this embodiment. 2+ Cu specific adsorption hollow fiber membrane 2+ The removal of Cu from the wastewater is achieved through treatment with the specific hollow fiber membrane. 2+ The concentrations were 0.12 mg / L and 0.08 mg / L, respectively, as shown in Table 9. These concentrations are lower than the limit of 0.5 mg / L for total copper discharge in irrigation water for paddy fields as specified in GB5084-2021 "Standards for Irrigation Water Quality". Therefore, these waters can be used directly for irrigation of paddy fields.

[0168] Table 9. Cu 2+ Hollow fiber membranes specifically adsorb Cu from wastewater in a dyeing and printing factory 2+ removal

[0169]

[0170] ②Cu in production wastewater 2+ Detection

[0171] The polysulfone Cu prepared by the method of the present invention 2+ A pretreatment detection method using a specific adsorption hollow fiber membrane involves repeatedly adsorbing the sample onto a polysulfone-specific hollow fiber membrane, followed by elution with HCl. The Cu content of the eluent is then determined using an atomic absorption spectrophotometer. 2+The concentration was determined, and the recovery rate of the composite membrane method was obtained, as shown in Table 10. Compared with the method in the national standard GB 5009.13-2017 "National Food Safety Standard - Determination of Copper in Food", the operation steps are greatly simplified, and it is also environmentally friendly.

[0172] Table 10. Cu in water 2+ Spiked recovery of the sample (μg / L)

[0173]

[0174] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a metal-specific adsorption composite membrane, characterized in that, The preparation method includes the following steps: S1.1 The metal template ions and functional monomers are fully reacted, and a crosslinking agent and an initiator are added to polymerize the metal template ions and functional monomers to generate a crosslinked polymer. The molar ratio of the heavy metal template ions to the functional monomers is 1:(1-8). S1.2 The metal template ions are eluted from the polymer using an eluent, and the metal ion-specific adsorbed particles are obtained after drying. S2. Preparation of a metal-specific adsorption composite membrane, comprising: S2.1 dissolving a polymer material substrate and a pore-forming agent in a solvent to obtain a membrane-forming solution, wherein the solvent is N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), or N-methylpyrrolidone (NMP). S2.2 Add metal ion-specific adsorption particles to the film-forming solution, stir, dissolve, and then add additives to obtain a film casting solution; the additives are selected from at least one of sodium dodecyl sulfonate (SDS), isopropanol, propylene glycol, oleic acid, polyvinylpyrrolidone (PVP), and ionic liquids. S2.3 The membrane casting solution is injected into a metering pump, extruded from the spinneret, passes through an air layer, enters a coagulation bath, solidifies and is then stretched, wound, and dried to obtain a metal-specific hollow fiber membrane; or The membrane casting solution is scraped onto the support layer, evaporated, and then immersed in a coagulation bath of deionized water or N,N-dimethylacetamide (DMAC) aqueous solution to obtain a metal-specific adsorption flat sheet membrane.

2. The preparation method according to claim 1, characterized in that, It also includes S2.4, which involves alternately stacking the metal-specific adsorption flat plate membrane and the guide net, spirally winding the central tube, and sealing the edges with resin to obtain the metal-specific adsorption spiral membrane.

3. The preparation method according to claim 1, characterized in that, The metal-specific adsorption particles are copper ion-specific adsorption particles, lead ion-specific adsorption particles, mercury ion-specific adsorption particles, antimony ion-specific adsorption particles, nickel ion-specific adsorption particles, cadmium ion-specific adsorption particles, and other metal-specific adsorption particles.

4. The preparation method according to claim 1, characterized in that, The preparation method includes at least one of the following methods selected from A to E: In A.S1.1, the functional monomers are chitosan, acrylic acid, methacrylic acid, 4-vinylpyridine, vinylimidazolium, thiocyanopropyldimethoxysilane, and 3-aminopropyltriethoxysilane. The crosslinking agent described in B.S1.2 is epichlorohydrin, ethylene glycol dimethacrylate, ethylene glycol dimethacrylate, and tetraethoxysilane; In C.S1.3, when the metal template ion is lead ion, the eluent is nitric acid, the functional monomer is methacrylic acid, and the crosslinking agent is ethylene glycol dimethacrylate; when the metal template ion is antimony ion, the eluent is hydrochloric acid, the functional monomer is thiocyanopropyl dimethoxysilane, and the crosslinking agent is cyclochloropropane; when the metal template ion is copper ion, the functional monomer is 3-aminopropyltriethoxysilane, the crosslinking agent is tetraethoxysilane, and the eluent is hydrochloric acid. D. The support layer is made of non-woven fabric, glass fiber layer, polyester, chlorofiber, nylon, or porous nylon; The evaporation time in E.S2.3 is 5-60 seconds, preferably 15-30 seconds.

5. The preparation method according to claim 1, characterized in that, In the film casting solution, the percentage weight ratio of polymer material substrate and pore-forming agent is 5-40% and 1-10%, respectively, preferably 10-20% for the polymer material substrate; or preferably 1-3% for the pore-forming agent. And / or the mass ratio of the additive to the film-forming solution is 1:(5-30), preferably 1:(10-20).

6. The preparation method according to claim 5, characterized in that, The ratio of the amount of metal-specific adsorbent particles to the film casting solution is (5-100) mg: 15 ml; preferably (30-50) mg: 15 ml, and more preferably (40-50) mg: 15 ml.

7. The preparation method according to claim 5, characterized in that, When the metal-specific adsorption composite membrane is used to remove or detect hydrophilic metal ions, the polymer material substrate is a hydrophilic material, preferably polyvinylidene fluoride, polyethersulfone, polysulfone, or polyvinyl chloride. The metal-specific adsorption composite membrane used to remove or detect metal ions is hydrophobic, and the polymer material substrate is hydrophobic, preferably polytetrafluoroethylene, polypropylene, or polyethylene; and / or The pore-forming agent in S2.2 is polyvinylpyrrolidone or polyethylene glycol.

8. The preparation method according to claim 1, characterized in that, The molar ratio of the metal template ion to the functional monomer is 1:(1-8), preferably 1:(2-4).

9. The metal-specific adsorption composite membrane obtained by the preparation method according to any one of claims 1-8.

10. The application of the metal-specific adsorption composite membrane according to claim 9 in the removal and / or detection of metal ions in water or food, preferably, the metal ions include lead ions, mercury ions, antimony ions, nickel ions, zinc ions, and cadmium ions.

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