Polyethyleneimine-modified silicon-free composite filter material for nuclear power water filtration and preparation method thereof

Abstract

The present invention discloses a silicon-free composite filter material for nuclear power water filtration modified by polyethyleneimine and a preparation method thereof, belonging to the technical field of filter materials. From the water inflow to the water outflow, there are a water-inflow support layer, a core filter layer and a hydrophobic support layer in order; the water-inflow support layer is used to support the core filter layer; the core filter layer is used for pore size interception and charge adsorption filtration; the hydrophobic support layer is used to evenly disperse the filtered clean water and support the core filter layer. It can not only filter solid suspended particles in the water by pore size, but also adsorb radioactive metal colloids and other negatively charged substances formed by corrosion products in the water through the positive charge generated by the TMC-PEI nanomembrane, and the chemical elements are very little dissolved. The present invention also discloses a preparation method for the above-mentioned silicon-free composite filter material for nuclear power water filtration modified by polyethyleneimine.

Description

Technical Field

[0001] The present invention relates to a modified water filtration composite filter material, in particular to a polyethyleneimine-modified nuclear power water filtration silicon-free composite filter material and a preparation method thereof, belonging to the technical field of filter materials. Background Art

[0002] With the continuous development of the nuclear power industry, the nuclear industry has higher and higher requirements for fluid cleanliness. It needs a filter material that can filter out solid suspended particles in the water and intercept radioactive isotope metal colloids formed by corrosion products in the water. For example 60 Co、 54 Mn, 59 Fe, 51 Cr, 125 Sb and 110M Ag, etc. Nuclear power plant water chemistry also places strict limits on the dissolution of chemical elements from filter media. Previously, nuclear power plant water filter elements were primarily made of glass fiber, but high silica dissolution persisted. Some power plants have even experienced silica exceeding standards, particularly those using boric acid enrichment. Currently, there is a growing demand for silica-free filter elements to replace the previous glass fiber elements. Some existing civilian silica-free filter media have poor radiation resistance and cannot be used in the nuclear island of a nuclear power plant.

[0003] Furthermore, traditional filter elements, including glass fiber elements, rely on pore size to intercept suspended solids in liquids. Filter media typically utilize a single layer or loosely packed multilayer structure. Due to technological limitations, achieving high-precision filtration of submicron impurities, including colloid interception, requires a very small pore size. This results in a very high initial pressure differential, shortening service life and increasing the amount of solid waste handled by nuclear power plants. Furthermore, the interception effect on radioactive metal colloids formed by corrosion products is limited, shortening the life of downstream resin beds and maintaining high levels of downstream radioactivity.

[0004] On April 2, 2019, a Chinese invention patent application, application number 2019100596629, disclosed a filter material for nuclear power plant primary water filters and its preparation method. The material uses glass fiber adhesive and nano-silica as raw materials, producing glass fiber paper through a wet process. This glass fiber paper is then double-sided laminated with an organic fiber layer to produce the filter material for nuclear power plant primary water filters. However, the material suffers from silicon dissolution issues and is not effective in intercepting radioactive colloids.

[0005] On September 20, 2019, a Chinese invention patent application, application number 2019105579352, disclosed a nuclear-grade water filter element and its preparation method. The invention comprises a base material made of micro-glass fiber with an alkali metal content greater than 9% and non-woven fabric laminated to the upper and lower surfaces of the base. The base and non-woven fabric are impregnated in a water-based resin, vacuum-pumped, and then dried and bonded together. However, the use of glass fiber leads to silica dissolution, and its lack of charge adsorption makes it unsuitable for current applications. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of the existing technology and provide a nuclear power water filtration silicon-free composite filter material and preparation method modified with polyethyleneimine, which can meet the requirements of filtering solid suspended particles and adsorbing radioactive metal colloid substances formed by corrosion products in water, while achieving low chemical element dissolution and high radiation resistance.

[0007] In order to solve the above technical problems, the present invention provides a polyethyleneimine-modified nuclear power water filtration silicon-free composite filter material, which comprises a water-incoming support layer, a core filter layer and a hydrophobic support layer from the water inlet to the water outlet;

[0008] The water-facing support layer is used to support the core filter layer;

[0009] The core filter layer is used for pore size interception and charge adsorption filtration;

[0010] The hydrophobic support layer is used to evenly disperse the filtered clean water and support the core filter layer.

[0011] In the present invention, the core filter layer comprises polyethyleneimine (PEI), polyester fiber outer and high molecular polymer material;

[0012] The polyester fiber accounts for 40-60% of the mass of the core filter layer;

[0013] The polyethyleneimine accounts for 0.5 to 25% by mass of the core filter layer;

[0014] The mass proportion of the high molecular polymer in the core filter layer is 15 to 59.5%.

[0015] In the present invention, the polyester fiber is a non-woven fabric obtained by mixing PBT (polybutylene terephthalate) and PET (polyethylene terephthalate);

[0016] The mass proportion of the PBT is 60-85%, and the mass proportion of the PET is 15%-40%.

[0017] In the present invention, the high molecular polymer material is any one of wood cellulose, nylon, and aramid, or a mixture of the above.

[0018] In the present invention, the polyester fiber weight range is 30-250g / m 2 , bulk density range 150-800kg / m 3 , the average fiber diameter is 1-5μm, and the average pore size is 0.3-25μm.

[0019] In the present invention, the polyethyleneimine exists in the form of TMC (trimethylenecarbonyl chloride)-PEI (polyethyleneimine) nanofilm, and the molecular weight of PEI in the TMC-PEI nanofilm ranges from 5000 to 70000.

[0020] In the present invention, the TMC-PEI nanofilm can generate a Zeta potential of not less than +30 mV in water with a pH of 4 to 8.5.

[0021] In the present invention, the mass proportion of silicon element in the composite filter material is less than 0.1%.

[0022] The present invention also provides a method for preparing a silicon-free composite filter material for nuclear power water filtration modified by polyethyleneimine, comprising the following steps:

[0023] S1. Prepare a first mixed fiber nonwoven fabric and a second mixed fiber nonwoven fabric, wherein the first mixed fiber nonwoven fabric is thicker than the second mixed fiber nonwoven fabric, the first mixed nonwoven fabric has an average pore size of 5-10 μm, and the second mixed nonwoven fabric has an average pore size of 0.5-2 μm;

[0024] S2, pre-depositing the first mixed fiber non-woven fabric in S1 as a substrate in a polyethyleneimine (PEI) solution, and then covering the surface of the polyethyleneimine (PEI) solution with a second mixed fiber non-woven fabric;

[0025] S3, quickly injecting an organic phase solution containing trimesoyl chloride (TMC) and an emulsifier (aminocarboxylate) so that it is evenly distributed in the aqueous phase and the upper layer of the second mixed fiber non-woven fabric;

[0026] S4, after reaching the set time, an independent TMC-PEI nanofilm is formed at the organic phase / water interface;

[0027] S5, moving the TMC-PEI nanofilm onto the mixed fiber nonwoven fabric in step S2 and compounding them;

[0028] S6, removing residue from the filter material obtained in step S5 and drying and cleaning it to obtain a core filter layer;

[0029] S7, compounding the water-facing support layer, the core filter layer obtained in S5 and the hydrophobic support layer to obtain a polyethyleneimine-modified nuclear power water filtration silicon-free composite filter material.

[0030] In the present invention, the time set in S4 is at least 72 hours.

[0031] In the present invention, the mass proportion of the emulsifier in S3 is 0.2%.

[0032] The beneficial effects of the present invention are: (1) The composite filter material can not only filter solid suspended particles in water by pore size, but also absorb radioactive metal colloids and other negatively charged substances formed by corrosion products in water through the positive charge generated by the TMC-PEI nanomembrane. The test shows that the filtration performance is excellent, the material is clean, and the dissolution is significantly less than that of chemical elements. (2) The silicon-free composite filter material for nuclear power water filtration modified with polyethyleneimine can fully meet the use under high radioactive conditions in the nuclear industry. The selected raw materials have been verified by irradiation testing. After 100KGy γ irradiation assessment, the performance has not deteriorated by more than 18%, proving that the radiation resistance is excellent; (3) The composite filter material of the present invention can be used to manufacture filter element products of various shapes and sizes. In addition to the nuclear industry, it is also suitable for the field of civil water filtration and treatment. For solid suspended particles, mechanical interception can be achieved by the pore size of the filter material; for radioactive isotope metal colloids formed by submicron or even nanometer-level corrosion products, for example 60 Co、 54 Mn, 59 Fe, 51 Cr, 125 Sb and 110M Ag, etc., which are negatively charged in water. The core layer of the nuclear power water filtration silicone-free composite filter material modified by polyethyleneimine can produce a Zeta potential of >+30mV in water, which can effectively adsorb the above-mentioned colloidal substances, thereby achieving high-precision filtration, high throughput, low pressure loss, and long life, saving long-term operating costs for users. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a schematic diagram of the structure of a silicon-free composite filter material for nuclear power water filtration modified with polyethyleneimine;

[0035] Figure 2 Schematic diagram of the preparation method of the composite filter material in Example 1. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0038] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0039] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like indicate positions or locations based on the positions shown in the accompanying drawings, or the positions or locations in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0040] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0041] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0042] Example 1

[0043] like Figure 1As shown, the silicon-free composite filter material for nuclear power water filtration modified by polyethyleneimine provided in this embodiment has three layers from the water inlet to the water outlet, which are the first layer being the water inlet support layer 1, the second layer being the core filter layer 2, and the third layer being the hydrophobic support layer 3. The three-layer structure is formed into a whole by hot pressing, and the structure is tight to avoid loose structure after subsequent processing, which affects the strength and filtration effect. At the same time, the thickness of the filter material is reduced after the whole is formed, and more effective filtration area can be provided in the same space.

[0044] In this embodiment, the main function of the water-facing support layer 1 is to support the core filter layer. In this embodiment, a PET polyester fiber non-woven fabric with an average pore size of 40 μm is used as the water-facing support layer 1.

[0045] The core filter layer 2 is a polyester fiber filter layer modified by polyethyleneimine, which has both pore size interception and charge adsorption filtration functions. In this embodiment, the core filter layer 2 adopts a mixture of melt-blown polybutylene terephthalate (PBT) non-woven fabric and polyethylene terephthalate (PET) (the mass proportion of PBT is 80%, and the mass proportion of PET is 20%) to form a polyester fiber non-woven fabric, plus nylon PA and TMC (trimethylenediamine chloride)-PEI (polyethyleneimine) nanomembrane. Among them, the mass proportion of polyester fiber in the core filter layer is 80%, the mass proportion of TMC (trimethylenediamine chloride)-PEI (polyethyleneimine) nanomembrane in the core filter layer is 15%; the mass proportion of nylon PA in the core filter layer is 5%. Among them, the melt-blown PBT polyester fiber cloth has a gram weight range of 120g / m 2 , bulk density range 450kg / m 3 , the average fiber diameter is 4.5μm and the average pore size is 5μm.

[0046] In this embodiment, the molecular weight of PEI in the TMC-PEI nanomembrane is 50,000.

[0047] In this embodiment, PET polyester fiber non-woven fabric with an average pore size of 30 μm is used as the hydrophobic support layer 3 .

[0048] like Figure 2 As shown, the preparation method of the polyethyleneimine-modified nuclear power water filtration silicon-free composite filter material of Example 1 is as follows:

[0049] S1, a first mixed fiber non-woven fabric and a second mixed fiber non-woven fabric obtained by melt-blowing a PBT polyester non-woven fabric composited with nylon, wherein the thickness of the first mixed fiber non-woven fabric is slightly greater than that of the second mixed fiber non-woven fabric, the average pore size of the first mixed non-woven fabric is 5 μm, and the average pore size of the second mixed non-woven fabric is 0.5 μm;

[0050] S2, pre-depositing the first mixed fiber non-woven fabric in S1 as a substrate in a polyethyleneimine (PEI) solution, and laying a second mixed fiber non-woven fabric on the surface of the polyethyleneimine (PEI) solution;

[0051] S3. Rapidly injecting an organic phase solution containing TMC (trimethylene carboxylic acid chloride, 50% by mass) and an emulsifier (aminocarboxylate, 0.2% by mass) so that it is evenly distributed on the upper layer of the aqueous phase, i.e., the upper layer of the second mixed fiber non-woven fabric;

[0052] S4, after standing for 72 hours, an independent TMC-PEI nanofilm was formed at the organic phase / water interface;

[0053] S5, lifting the first mixed fiber non-woven fabric and the second mixed fiber non-woven fabric, moving the TMC-PEI nanofilm onto the first mixed fiber non-woven fabric in step S1, and performing hot pressing and laminating by hot rolling rollers;

[0054] S6. Soaking or rinsing the filter material obtained in step S5 with ultrapure water to remove residual chemicals and fiber fragments, and then drying and cleaning to obtain a core filter layer of a polyethyleneimine-modified nuclear power water filtration silicon-free composite filter material;

[0055] S7. Hot-press and laminate the two sides of the core filter layer using PET polyester fiber non-woven fabrics to finally form a polyethyleneimine-modified nuclear power water filtration silicone-free composite filter material.

[0056] The average pore size of the core filter layer of the composite filter material prepared in this embodiment is 0.43 μm.

[0057] The composite filter material prepared in Example 1 is suitable for water with a pH range of 3 to 11, covering all operating conditions in nuclear power plants and meeting the water filtration requirements of various reactor types. The material contains no silicon, eliminating the potential risk of silicon dissolution. The TMC-PEI nanomembrane produces a zeta potential of +30mV in water with a pH range of 3 to 8.5. Testing has shown a filtration efficiency exceeding 99.5% at a 0.5μm filtration accuracy. This composite filter material can be used to manufacture pleated filter elements. The finished filter elements exhibit high flowability and low pressure drop. They not only intercept solid suspended particles in water through their pore size but also charge-absorb colloids in the water, making them suitable for most high-precision water filtration applications.

[0058] In the composite filter material prepared in this embodiment, the mass proportion of silicon is less than 0.1%. Because the materials used in the preparation process are all polymer materials, the main chemical elements are carbon, hydrogen, oxygen, nitrogen and very few other elements. At the same time, no other chemical substances are added in the production process, stainless steel utensils are used, and the places where the equipment contacts the materials are all surface treated to avoid material contamination. The scanning electron microscope-energy spectrometer measurement shows that the chemical element dissolution is significantly less than that of the glass fiber filter material used for nuclear power water filtration in the past. Taking silicon as an example, the dissolution concentration of silicon (a small amount of inclusions) in the composite filter material is less than 2ppb, and it is not continuously released; while the dissolution concentration of silicon in traditional glass fiber filter material is 200-300ppb, which will be continuously released. The composite filter material can be used for water filtration in the primary circuit and auxiliary systems of nuclear power plants, as well as non-nuclear power plant applications including drinking water treatment, process water purification, industrial sewage treatment, medical wastewater treatment and water filtration treatment containing radioactive substances.

[0059] Example 2

[0060] In this embodiment, PET polyester fiber non-woven fabric with an average pore size of 35 μm is used as the water-facing support layer.

[0061] In this embodiment, the core filter layer 2 is constructed from a meltblown blend of polybutylene terephthalate (PBT) nonwoven fabric and polyethylene terephthalate (PET) (75% by weight PBT, 25% by weight PET), supplemented with aramid and a TMC (trimesoyl chloride)-PEI (polyethyleneimine) nanomembrane. The polyester fiber accounts for 70% of the core filter layer by weight, the TMC (trimesoyl chloride)-PEI (polyethyleneimine) nanomembrane accounts for 20% by weight, and the aramid fiber accounts for 10% by weight. The meltblown PBT polyester fiber fabric has a grammage range of 250 g / m², a bulk density range of 550 kg / m³, an average fiber diameter of 4 μm, and an average pore size of 1 μm.

[0062] In this embodiment, the molecular weight of PEI in the TMC-PEI nanomembrane is 70,000.

[0063] In this embodiment, PET polyester fiber non-woven fabric with an average pore size of 35 μm is used as the hydrophobic support layer.

[0064] like Figure 2 As shown, the preparation method of the polyethyleneimine-modified nuclear power water filtration silicon-free composite filter material of Example 2 is as follows:

[0065] S1-S3 are the same as in Example 1;

[0066] S4, after standing for 75 h, an independent TMC-PEI nanofilm was formed at the organic phase / water interface;

[0067] S5-S7 are the same as in Example 1.

[0068] The average pore size of the core filter layer of the composite filter material prepared in this embodiment is 0.26 μm.

[0069] The composite filter material prepared in Example 2 is suitable for water with a pH range of 4 to 9.5, has good acid and alkali resistance, and has a strong charge adsorption capacity. After iron colloid filtration testing, the initial efficiency can reach 99.5%, and at the same time, there is no excessive dissolution of chemical elements, which can meet the water chemical working conditions of various reactor types of nuclear power plants; after testing, the TMC-PEI nanomembrane can produce a Zeta potential of +50mV in water with a pH of 7.2 (the pH value of the normal operating condition of the primary loop of Hualong 1), which is much higher than other filter materials with charge adsorption capacity used in the nuclear industry. The filter element made of this filter material has a filtration accuracy of 0.1μm and a filtration efficiency of greater than 98.5%. The composite filter material has a compact structure, higher mechanical properties, excellent radiation resistance, will not loosen in water, is easy to shape, has high precision, can effectively remove radioactive colloid substances formed by transition metal corrosion products, and helps to reduce system radioactivity.

[0070] Example 3

[0071] In this embodiment, PET polyester fiber non-woven fabric with an average pore size of 45 μm is used as the water-facing support layer.

[0072] In this embodiment, the core filter layer is made of a mixture of melt-blown polybutylene terephthalate (PBT) non-woven fabric and polyethylene terephthalate (PET) (the mass proportion of PBT is 85%, and the mass proportion of PET is 15%) to form a polyester fiber non-woven fabric, and then added with wood cellulose and TMC (trimethylenediamine chloride)-PEI (polyethyleneimine) nanomembrane. Among them, the mass proportion of polyester fiber in the core filter layer is 65%, the mass proportion of TMC (trimethylenediamine chloride)-PEI (polyethyleneimine) nanomembrane in the core filter layer is 10%; the mass proportion of wood cellulose in the core filter layer is 25%. Among them, the melt-blown PBT polyester fiber cloth has a gram weight range of 100g / m 2 , bulk density range 400kg / m 3 , the average fiber diameter is 5μm and the average pore size is 8μm.

[0073] In this embodiment, the molecular weight of PEI in the TMC-PEI nanomembrane is 20,000.

[0074] In this embodiment, PET polyester fiber non-woven fabric with an average pore size of 30 μm is used as the hydrophobic support layer.

[0075] The preparation method of the polyethyleneimine-modified nuclear power water filtration silicon-free composite filter material of Example 3 is as follows:

[0076] S1-S3 are the same as in Example 1;

[0077] S4, after standing for 80 hours, an independent TMC-PEI nanofilm was formed at the organic phase / water interface;

[0078] S5-S7 are the same as in Example 1.

[0079] The average pore size of the core filter layer of the composite filter material prepared in this embodiment is in the range of 5 μm.

[0080] The composite filter material prepared in Example 3 is suitable for water with a pH range of 4 to 9.5, exhibits excellent acid and alkali resistance, and can meet the water filtration requirements of various nuclear power plant types. The TMC-PEI nanomembrane produces a zeta potential of +30 mV in water with a pH range of 4 to 8.5. Testing demonstrates a filtration efficiency exceeding 99% at a 0.5 μm filter fineness. This composite filter material exhibits excellent foldability, easy shaping, high flow capacity, and low pressure drop, making it suitable for most high-precision water filtration applications.

[0081] The composite filter materials obtained in each embodiment were tested using submicron dust test results as follows:

[0082]

[0083] In the embodiments of the present invention, a radiation-resistant polymer material that does not contain silicon elements and an organic phase solution containing trimesoyl chloride (TMC) and an emulsifier (aminocarboxylate) are used, which not only solves the hydrophilicity of the material surface, but also increases the surface charge of the material, ensuring that its filtration effect is not affected by the pH value of the medium.

[0084] Based on the above-described preferred embodiments of the present invention and the above-described inventive content, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of the present invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A silicon-free composite filter material for nuclear power water filtration modified with polyethyleneimine, characterized by: From the water inflow to the water outflow, there are the water inflow support layer, the core filter layer and the hydrophobic support layer; The water-facing support layer is used to support the core filter layer; The core filter layer is used for pore size interception and charge adsorption filtration; The hydrophobic support layer is used to evenly disperse the filtered water and support the core filter layer; The core filter layer includes polyethyleneimine (PEI), polyester fiber and other high molecular polymer materials; The polyester fiber accounts for 65-80% of the mass of the core filter layer; The polyethyleneimine accounts for 10 to 20% by mass of the core filter layer; The high molecular weight polymer accounts for 5 to 25% of the mass of the core filter layer; The polyester fiber is a non-woven fabric obtained by mixing PBT (polybutylene terephthalate) and PET (polyethylene terephthalate); The mass proportion of PBT is 75-85%, and the mass proportion of PET is 15%-25%; The polyethyleneimine exists in the form of TMC (trimethylenecarbonyl chloride)-PEI (polyethyleneimine) nanofilm, and the molecular weight of PEI in the TMC-PEI nanofilm ranges from 20,000 to 70,000; The TMC (trimethylene carboxylic acid chloride)-PEI (polyethylene imine) nanofilm formation process uses a mixed organic phase solution containing TMC (trimethylene carboxylic acid chloride) and aminocarboxylic acid ester, wherein the aminocarboxylic acid ester accounts for 0.2% by weight; The TMC-PEI nanofilm can generate a Zeta potential of not less than +30 mV in water with a pH of 4 to 8.5; The mass proportion of silicon element in the composite filter material is less than 0.1%.

2. The polyethyleneimine-modified silicon-free composite filter material for nuclear power water filtration according to claim 1, characterized in that: The high molecular polymer material is any one of wood cellulose, nylon, and aramid, or a mixture of the above.

3. The polyethyleneimine-modified silicon-free composite filter material for nuclear power water filtration according to claim 1 or 2, characterized in that: The polyester fiber weight range is 100-250g / m 2 , bulk density range 400-550kg / m 3 , average fiber diameter 3-5 , average pore size 1-8 .

4. The polyethyleneimine-modified silicon-free composite filter material for nuclear power water filtration according to any one of claims 1 to 3, characterized in that: The preparation method of the polyethyleneimine-modified silicon-free composite filter material for nuclear power water filtration comprises the following steps: S1. Preparing a first mixed fiber nonwoven fabric and a second mixed fiber nonwoven fabric, wherein the first mixed fiber nonwoven fabric is thicker than the second mixed fiber nonwoven fabric; S2, pre-depositing the first mixed fiber non-woven fabric in S1 as a substrate in a polyethyleneimine (PEI) solution, and then covering the surface of the polyethyleneimine (PEI) solution with a second mixed fiber non-woven fabric; S3, quickly injecting the organic phase solution containing trimesoyl chloride (TMC) and aminocarboxylate so that it is evenly distributed in the aqueous phase and the upper layer of the second mixed fiber non-woven fabric; S4, after reaching the set time, an independent TMC-PEI nanofilm is formed at the organic phase / water interface; S5, moving the TMC-PEI nanofilm onto the first mixed fiber non-woven fabric in step S2 and compounding them; S6, removing residue from the filter material obtained in step S5 and drying and cleaning it to obtain a core filter layer; S7, compounding the water-facing support layer, the core filter layer, and the hydrophobic support layer to obtain a polyethyleneimine-modified nuclear power water filtration silicon-free composite filter material; The time set in S4 is at least 72 hours.

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