PA-based filtering material for filtering gel particles in nuclear power water

Abstract

The invention belongs to the field of filtering materials, and relates to a PA-based filtering material for filtering gel particles in nuclear power water. The PA-based filter material is a textile composed of PA fibers with the surfaces grafted with PEI, and the PEI is hyperbranched polyethyleneimine. The molecular weight M of the PEI, the Zertower potential Ub1 of the textile when the pH value is equal to 7, the average physical semi-aperture Rp of the textile, the porosity rho of the textile, the average physical radius rp of gel particles in nuclear water subjected to target removal, the Zertower potential Ub2 of the gel particles in the nuclear water subjected to target removal and the apparent velocity Vs of the nuclear water meet a certain relational expression. The filter material can be used for filtering out gel particles in nuclear power water, physical aperture screening and PEI charge adsorption are combined, the particle size of the gel particles is adapted, electrostatic adsorption is enhanced, the retention rate of the gel particles in the nuclear power water reaches about 99.0%, and the problems that a traditional filter material is high in penetration rate and filtering of deformed particles fails are solved.

Description

Technical Field

[0001] This invention belongs to the field of filtration materials and relates to a PA-based filtration material for filtering out gel particles in nuclear power plant water. Background Technology

[0002] In the field of nuclear power plant water treatment, gel particles are formed from colloidal substances, corrosion products, or organic polymers, with sizes ranging from nanometers to micrometers, and possess viscoelasticity, deformability, and adsorption properties. These particles originate from metal corrosion in reactor coolant systems (such as oxides of iron, nickel, and chromium), decomposition of chemical additives, or microbial metabolic products. Due to the unique physicochemical properties of gel particles, they may adsorb radioactive nuclides (such as...) in nuclear power plant water systems. 60 Co、 137 Cs) form radioactive colloids, greatly increasing the complexity of water treatment. The deposition behavior of gel particles not only leads to decreased heat transfer efficiency and localized corrosion, but may also increase the risk of radiation by carrying radioactive materials. In addition, gel particles can clog the pores of ion exchange resins, reducing treatment efficiency and increasing operation and maintenance costs.

[0003] Polyamide (PA) boasts excellent chemical stability, resisting corrosion from various chemicals; it possesses high mechanical strength and abrasion resistance, allowing it to withstand multiple filtration cycles; and its excellent hydrophilicity enables liquids to pass through quickly. These advantages make PA a viable filtration material. PA filter materials are widely used in chemical, pharmaceutical, food and beverage, electronic ultrapure water preparation, and industrial wastewater treatment industries, and are particularly suitable for applications requiring high filtration precision and chemical corrosion resistance.

[0004] However, there is currently a lack of data directly applicable to the treatment of gel particles in nuclear power plant water using PA filter materials. However, we can refer to the filtration performance of PA for colloidal particles in similar wastewater treatment or other fields. Studies have shown that when using PA microporous membranes with pore sizes of 0.1-0.45 μm to filter wastewater containing colloidal particles, the filtration efficiency is low. This is because some colloidal particles deform, passing through pores smaller than their original size, thus affecting the filtration effect. Gel particles in nuclear power plant water have similar properties to the aforementioned colloidal particles. When subjected to external forces during the filtration process, these particles exhibit strong deformation characteristics, allowing them to pass through the smaller pore size of the PA filter material. Therefore, PA filter materials cannot meet the stringent purification requirements of nuclear power plant water treatment in practical applications.

[0005] Patent application CN118454343A discloses a silicon-free composite filter material for nuclear power plant water filtration. Its core filter layer comprises polyethyleneimine, polyester fiber, and other polymer materials, with nylon being one of the other polymer materials. This core filter layer is used for pore size interception and charge adsorption filtration. However, this silicon-free composite filter material for nuclear power plant water filtration has a complex structure, and the nylon content is relatively small, failing to fully utilize nylon's advantages of chemical corrosion resistance and high mechanical strength. When treating nuclear power plant water, the limited nylon content results in two main problems: firstly, the overall chemical stability of the composite filter material is poor, making it difficult to withstand the erosion of complex chemicals in the nuclear power plant water for extended periods, thus reducing the filter material's lifespan; secondly, the mechanical properties of the filter material are limited, making it prone to damage or deformation under high water pressure or frequent filtration operations, affecting the filtration accuracy and interception effect on impurities such as gel particles.

[0006] In summary, the filtration challenge of gel particles in nuclear power plant water treatment urgently needs to be addressed. It is necessary to develop filtration technologies and materials that can effectively address the deformation characteristics of gel particles in order to meet the stringent water purification requirements of the nuclear power industry. Summary of the Invention

[0007] The purpose of this invention is to solve the problems existing in the prior art and to provide a PA-based filter material for filtering out gel particles in nuclear power plant water.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] PA-based filter material used to remove gel particles from nuclear power plant water is a textile composed of PA fibers with PEI grafted onto the surface. PEI is hyperbranched polyethyleneimine.

[0010] The molecular weight M of PEI, the Zeta potential Ub1 of the textile at pH=7, the average physical half-pore size Rp of the textile, the porosity ρ of the textile, the average physical radius rp of the gel particles in the target-removed nuclear power plant water, the Zeta potential Ub2 of the gel particles in the target-removed nuclear power plant water, and the apparent flow rate Vs of the nuclear power plant water satisfy the following relationship:

[0011] (rp×(1-0.2(Vs / ρ / Ka)))≥0.729(Rp-(kb2×kb1×((Ub1-Ub2)^0.19)×(Km^1 / 3)×β^0.2));

[0012] In the formula, the unit of rp is μm;

[0013] The unit of Vs is mm / s;

[0014] The value of Ka is 2, and the unit is mm / s;

[0015] The unit of Rp is μm;

[0016] kb2 is related to Vs / ρ. When Vs / ρ>5mm / s, kb2=0, and when Vs / ρ≤5mm / s, kb2=1.

[0017] The value of kb1 is 0.019, and the unit is μm×(mv^-0.19)×(Da^-1 / 3);

[0018] The unit of Ub1 is mV;

[0019] The unit of Ub2 is mV;

[0020] Km is related to the molecular weight M of PEI. When M≤70000Da, Km=M, and when M>70000Da, Km=70000Da.

[0021] β is related to Vs, ρ, and Kv. If Vs / ρ≥Kv, then β=0; otherwise, β=1-Vs / ρ / Kv. The value of Kv is 5, and the unit is mm / s.

[0022] The derivation process of the above relation is as follows:

[0023] The filtration efficiency Fe depends on the average equivalent semi-pore size Re (μm) of the textile and the average equivalent radius re (μm) of the gel particles; when re > Re, Fe = 100%; when re ≤ Re, Fe = (re / Re)^(1 / 3) × 100%.

[0024] The filtration effect is relatively ideal when Fe ≥ 90%. According to the above analysis, in order to make Fe ≥ 90%, it is necessary to control (re / Re) ≥ 0.729, that is, control re ≥ 0.729Re.

[0025] The average equivalent semi-pore size Re (μm) of the textile depends on the average physical semi-pore size Rp (μm), the actual flow velocity Va (mm / s) of the nuclear power water, and the boundary layer thickness Tb1 (μm) of the textile. Experiments show that Re = Rp - (Tb1 × β^0.2), where β is related to Va and Kv. If Va ≥ Kv, then β = 0; otherwise, β = 1 - Va / Kv. The value of Kv is negatively correlated with the amount of residual negative charge on the surface of the textile. The more residual negative charge on the surface of the textile, the smaller the value of Kv; conversely, the fewer residual negative charge on the surface of the textile, the larger the value of Kv. In this invention, the textile is composed of PA fibers grafted with PEI. The carboxyl groups of PA carry negative charges, the amino groups of PA carry positive charges, and the amino groups of PEI carry positive charges. The amount of residual negative charge on the surface of the textile is relatively small. Therefore, the value of Kv is set to 5, with the unit being mm / s.

[0026] The actual flow velocity Va (mm / s) of the nuclear power plant water depends on the apparent flow velocity Vs (mm / s) of the nuclear power plant water and the porosity ρ of the textile (dimensionless, for example, if ρ is 30%, then ρ is 0.3), Va = Vs / ρ;

[0027] The boundary layer thickness Tb1 (μm) of the textile depends on the Zeta potential Ub1 (mV) of the textile at pH=7, the Zeta potential Ub2 (mV) of the gel particles, and the molecular weight M (Da) of the PEI. Experiments show that Tb1 = kb2 × kb1 × ((Ub1 - Ub2)^0.19) × (Km^1 / 3). When M ≤ 70000 Da, Km = M; when M > 70000 Da, Km = 70000 Da; when Va > 5 mm / s, kb2 = 0; when Va ≤ 5 mm / s, kb2 = 1. The value of kb1 is positively correlated with the amount of residual positive charge on the surface of the textile. The more residual positive charge on the surface of the textile, the larger the value of kb1, and vice versa. In this invention, the textile is composed of PA fibers grafted with PEI. The carboxyl groups of PA carry negative charges, the amino groups of PA carry positive charges, and the amino groups of PEI carry positive charges. The amount of residual positive charge on the surface of the textile is relatively large. Therefore, the value of kb1 is set to 0.019, with the unit being μm×(mv^-0.19)×(Da^-1 / 3).

[0028] therefore,

[0029] Re=Rp-(Tb1×β^0.2)=Rp-(kb2×kb1×((Ub1-Ub2)^0.19)×(Km^1 / 3)×β^0.2).

[0030] The average equivalent radius re (μm) of the gel particles depends on the physical average radius rp (μm) of the gel particles and the deformation factor Df (dimensionless) of the gel particles. Experiments show that re = rp × Df, Df = 1 - 0.2 (Va / Ka), where Ka is 2 and the unit is mm / s, i.e., re = rp × (1 - 0.2 (Va / Ka)) = rp × (1 - 0.2 (Vs / ρ / Ka)).

[0031] Control re ≥ 0.729Re, i.e., control

[0032] (rp×(1-0.2(Vs / ρ / Ka)))≥0.729(Rp-(kb2×kb1×((Ub1-Ub2)^0.19)×(Km^1 / 3)×β^0.2)).

[0033] Therefore, to achieve the ideal filtration effect, it is necessary to control...

[0034] (rp×(1-0.2(Vs / ρ / Ka)))≥0.729(Rp-(kb2×kb1×((Ub1-Ub2)^0.19)×(Km^1 / 3)×β^0.2)).

[0035] When the particle size distribution of gel particles in nuclear power plant water is wide, the gel particles can be removed in steps. For example, the gel particles in nuclear power plant water can be removed in three steps. The first step is to target the gel particles with larger particle sizes as the gel particles to be removed, and to filter them with PA-based filter materials with suitable PEI molecular weight M, Zeta potential Ub1, average physical half-pore size Rp, and porosity ρ. The second step is to target the gel particles with medium particle sizes as the gel particles to be removed, and to filter them with PA-based filter materials with suitable PEI molecular weight M, Zeta potential Ub1, average physical half-pore size Rp, and porosity ρ. The third step is to target the gel particles with smaller particle sizes as the gel particles to be removed, and to filter them with PA-based filter materials with suitable PEI molecular weight M, Zeta potential Ub1, average physical half-pore size Rp, and porosity ρ.

[0036] As a preferred technical solution:

[0037] The PA-based filter material for removing gel particles from nuclear power plant water, as described above, has a PEI molecular weight M of 3k-100kDa, preferably 3k-70kDa, a Zeta potential Ub1 of 20-58mV at pH=7, an average physical semi-pore size Rp of 0.1-6.1μm, preferably 0.8-6.1μm, a porosity ρ of 30-75%, preferably 50-75%, an average physical radius rp of the gel particles in the target nuclear power plant water to be removed of 0.05-5μm, a Zeta potential Ub2 of the gel particles in the target nuclear power plant water to be removed of no more than -5mV, and an apparent flow rate Vs of 0.333-1.000mm / s.

[0038] This invention investigated the relationship between the molecular weight M of PEI and the Zeta potential Ub1 of textiles at pH=7. The results showed that when the molecular weight M of PEI was between 3k and 70kDa, the Zeta potential Ub1 of textiles at pH=7 gradually increased with the increase of the molecular weight M of PEI. When the molecular weight M of PEI exceeded 70kDa, the Zeta potential Ub1 of textiles at pH=7 tended to stabilize and no longer increased. Therefore, this invention sets the molecular weight M of PEI to 3k-70kDa.

[0039] The PA-based filter material described above for filtering out gel particles in nuclear power plant water has a rejection rate (i.e., the actual measured filtration efficiency) of more than 95.0% for the gel particles in the target nuclear power plant water, with a maximum of 99.0%.

[0040] The PA-based filter material described above for removing gel particles from nuclear power plant water has PA fibers grafted with PEI on its surface with a diameter of 0.1-15 μm; the textile weight is 15-200 g / m². 2 Preferred concentration: 15-100g / m 2 The bubble point flow rate is 0.003-0.03 L / min.

[0041] The PA-based filter material used to remove gel particles from nuclear power plant water, as described above, uses PA6 or PA66 as raw material with a molecular weight of 15k-30kDa as PA fiber.

[0042] The manufacturing process of the PA-based filter material used to remove gel particles from nuclear power plant water, as described above, is as follows: PA substrate activation → PEI surface grafting;

[0043] The PA substrate is PA meltblown nonwoven fabric or PA electrospun nanofiber membrane.

[0044] PA substrate activation involves acid hydrolysis of the PA substrate to form more carboxyl groups.

[0045] Surface grafting of PEI involves grafting PEI onto the surface of an activated PA substrate.

[0046] This invention investigated the change in carboxyl content of PA substrate after acid treatment. Specifically, PA6 meltblown nonwoven fabric was first treated with a citric acid monohydrate aqueous solution with a pH of 2.0 at 80°C for 30 minutes. After washing with water, the carboxyl content of PA6 meltblown nonwoven fabric was tested by potentiometric titration according to the national standard GB / T 38138-2019. The results showed that the carboxyl content of PA6 meltblown nonwoven fabric increased from 196 mmol / kg before acid treatment to 216 mmol / kg after acid treatment, an increase of 10.2%. This is because citric acid molecules cannot penetrate into the interior of PA6 fibers, and the increased carboxyl groups are concentrated on the surface of PA6 fibers, which helps to improve the subsequent grafting reaction between PEI and carboxyl groups. Therefore, this invention preferably uses acid treatment to activate the PA substrate before subsequent surface grafting of PEI.

[0047] The PA-based filter material for filtering gel particles in nuclear power plant water, as described above, has the following specific activation process: the PA substrate is immersed in an acid solution at 40-95°C for 15-120 minutes, then washed with water and dried. The pH value of the acid solution is 1.0-3.0, and the acid in the acid solution is one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, acetic acid, and citric acid. The mass ratio of the PA substrate to the acid solution is 1:5-20, preferably 1:5-10 or 1:10-20.

[0048] The specific process of surface grafting PEI is as follows: the activated PA substrate is immersed in PEI solution at 40-95℃ for 15-120 min, then washed with water and dried. The concentration of PEI solution is 0.5-5.0 wt%, and the mass ratio of activated PA substrate to PEI solution is 1:5-10.

[0049] The manufacturing process of the PA-based filter material used to remove gel particles from nuclear power plant water, as described above, is as follows: PA resin pulverization → activation → surface grafting of PEI → preparation of spinning solution → electrospinning.

[0050] Activation involves acid hydrolysis of the pulverized PA resin to form more carboxyl groups.

[0051] Surface grafting of PEI involves grafting PEI onto the surface of activated PA resin.

[0052] The spinning solution is prepared by dissolving the PA resin with PEI grafted onto its surface in an organic solvent.

[0053] The PA-based filter material used to remove gel particles from nuclear power plant water, as described above, has a particle size of 200-1000 mesh after the PA resin is pulverized.

[0054] The specific activation process is as follows: the pulverized PA resin is immersed in an acid solution at 40-95℃ for 15-120 minutes, then washed with water and dried. The pH value of the acid solution is 1.0-3.0, and the acid in the acid solution is one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, acetic acid and citric acid.

[0055] The specific process for surface grafting PEI is as follows: the activated PA resin is immersed in a PEI solution at 40-95℃ for 15-120 minutes, then washed with water and dried. The concentration of the PEI solution is 0.5-5.0 wt%.

[0056] The organic solvent is hexafluoroisopropanol, and the concentration of the spinning solution is 5-25 wt%.

[0057] The process parameters for electrospinning include: spinning voltage 15-30kV, receiving distance 10-30cm, and spinning speed 0.01-1mL / min.

[0058] Beneficial effects:

[0059] (1) The PA-based filter material of the present invention for filtering gel particles in nuclear power water adopts a combination of physical pore size sieving and PEI charge adsorption, which is adapted to the particle size of gel particles and enhances electrostatic adsorption. The retention rate is greater than 95.0%, and up to 99.0%, which solves the problems of high penetration rate and failure of deformable particle filtration in traditional filter materials.

[0060] (2) The PEI amino groups in the PA-based filter material used in this invention for filtering out gel particles in nuclear power plant water can chelate radionuclides, reduce the risk of radioactive colloid diffusion, and improve the safety of nuclear power plant water treatment.

[0061] (3) The PA-based filter material of the present invention for filtering out gel particles in nuclear power water has a hydrophilic surface and a porous structure, which can reduce particle deposition and clogging. The electrostatic repulsion effect facilitates backwashing and cleaning, and extends the service life of the filter material.

[0062] (4) The PA-based filter material of the present invention for filtering out gel particles in nuclear power plant water has high mechanical strength and chemical stability, and can withstand the high pressure and strong corrosion environment of nuclear power plant water, ensuring long-term stable operation.

[0063] (5) The PA-based filter material of the present invention for filtering out gel particles in nuclear power plant water has a simple preparation process, low cost, and is suitable for industrial production. Detailed Implementation

[0064] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0065] The following are the test methods for the relevant performance indicators in each embodiment:

[0066] The molecular weight M of PEI was determined by gel permeation chromatography (GPC). PEI samples were prepared into solutions with a concentration of 1-5 mg / mL. Tetrahydrofuran was used as the mobile phase, and the flow rate was set to 1.0 mL / min. A PLgelMIXED-C gel chromatography column was used, and the samples were detected by a differential refractive index detector (RI) and a light scattering detector (LS). A standard curve was plotted using a standard polymer (polystyrene) with a known molecular weight as a standard. The molecular weight M value of PEI was read and recorded directly from the standard curve or the instrument software.

[0067] The mean physical radius rp of the gel particles in the target nuclear power plant water to be removed: determined according to ISO 22412:2017.

[0068] Zeta potential Ub2 of gel particles in nuclear power plant water to be removed: The zeta potential Ub2 of gel particles in nuclear power plant water was determined by electrophoretic light scattering method. 5-10 mL of nuclear power plant water sample was placed in the sample cell of the zeta potential analyzer. The instrument applied an electric field to both ends of the sample to cause the charged gel particles to undergo electrophoretic motion. The electrophoretic mobility of the particles was measured using the laser Doppler effect. Combined with parameters such as the dielectric constant and viscosity of the sample, the zeta potential Ub2 of the gel particles was calculated according to the Henry equation.

[0069] Bubble point flow rate: Determined according to GB / T 32361-2015 "Test Methods for Pore Size of Separation Membranes - Bubble Point and Average Flow Rate Method".

[0070] Zeta potential Ub1 of textiles at pH=7: The Zeta potential Ub1 of the material surface was determined by the flow potentiometric method. The textile was cut into strips of 1×5cm and fixed in the sample holder of the flow potentiometer. A 0.01mol / L KCl aqueous solution (pH=7) was used as the electrolyte, and the flow rate was controlled at 1mL / min. The flow potential generated when the electrolyte flows through the surface of the textile was measured. Combined with the dielectric constant and viscosity parameters of the solution, the Zeta potential Ub1 of the textile surface was calculated according to the Henry equation.

[0071] The average physical semi-pore size Rp of textiles was determined according to GB / T 32361-2015 "Separation Membrane Pore Size Test Method Bubble Point and Average Flow Rate Method".

[0072] Porosity ρ of textiles: determined according to Method A in GB / T 42697-2023 "Test Method for Porosity of Nonwoven Fabrics".

[0073] The retention rate of textiles for gel particles in the target-removed nuclear power plant water: First, the concentration C0 of gel particles in the target-removed nuclear power plant water is determined by laser particle size analyzer. Then, the target-removed nuclear power plant water is filtered through textiles, and the filtered liquid is collected. The concentration C1 of gel particles is determined. The retention rate of textiles for gel particles in the target-removed nuclear power plant water is calculated according to the formula Retention rate = (C0-C1) / C0×100%.

[0074] Example 1A

[0075] The preparation method of PA-based filter material for filtering gel particles from nuclear power plant water includes the following specific steps:

[0076] (1) Prepare raw materials;

[0077] PA substrate: PA meltblown nonwoven fabric; wherein PA is PA6 with a molecular weight of 20kDa;

[0078] Acid solution: solute is sulfuric acid, pH value is 2.0, solvent is water;

[0079] PEI solution: concentration 0.5wt%, solute PEI is hyperbranched polyethyleneimine, molecular weight M is 70kDa, solvent is water;

[0080] (2) PA substrate activation;

[0081] The PA substrate was immersed in an acid solution at 80°C for 15 minutes, then washed with water and dried to obtain the activated PA substrate; wherein the mass ratio of PA substrate to acid solution was 1:15.

[0082] (3) Surface grafting of PEI;

[0083] The activated PA substrate was immersed in a PEI solution at 95°C for 15 minutes, with a mass ratio of activated PA substrate to PEI solution of 1:8. After immersion, the substrate was washed with water and dried to obtain a textile composed of PA fibers surface-grafted with PEI. This textile is used as a PA-based filter material for removing gel particles from nuclear power plant water. The diameter of the PEI-grafted PA fibers is 15 μm, and the weight of the textile is 100 g / m². 2 The bubble point flow rate was 0.03 L / min, the Zeta potential Ub1 of the textile at pH=7 was 58 mV, the average physical semi-pore size Rp of the textile was 2.2 μm, and the porosity ρ of the textile was 60%.

[0084] Example 1B

[0085] A method for filtering gel particles in nuclear power plant water, using the PA-based filter material for filtering gel particles in nuclear power plant water prepared in Example 1A;

[0086] The average physical radius rp of the gel particles in the target removed nuclear power plant water is 0.5 μm, the Zeta potential Ub2 of the gel particles in the target removed nuclear power plant water is -10 mV, and the apparent flow velocity Vs of the nuclear power plant water is 0.333 mm / s.

[0087] The tests showed that the final rejection rate of gel particles in the target nuclear power plant water was 97.6%.

[0088] Example 2A

[0089] The preparation method of PA-based filter material for filtering gel particles from nuclear power plant water includes the following specific steps:

[0090] (1) Prepare raw materials;

[0091] PA substrate: PA electrospun nanofiber membrane; wherein PA is PA6 with a molecular weight of 15kDa;

[0092] Acid solution: solute is hydrochloric acid, pH value is 3.0, solvent is water;

[0093] PEI solution: concentration 3.0 wt%, solute PEI is hyperbranched polyethyleneimine, molecular weight M is 10 kDa, solvent is water;

[0094] (2) PA substrate activation;

[0095] The PA substrate was immersed in an acid solution at 40°C for 100 min, then washed with water and dried to obtain the activated PA substrate; wherein the mass ratio of PA substrate to acid solution was 1:10.

[0096] (3) Grafting PEI;

[0097] The activated PA substrate was immersed in a PEI solution at 60°C for 80 minutes, with a mass ratio of activated PA substrate to PEI solution of 1:5. After immersion, the substrate was washed with water and dried to obtain a textile composed of PA fibers surface-grafted with PEI. This textile is used as a PA-based filter material for removing gel particles from nuclear power plant water. The diameter of the PEI-grafted PA fibers is 0.1 μm, and the weight of the textile is 15 g / m². 2 The bubble point flow rate was 0.01 L / min, the Zeta potential Ub1 of the textile at pH=7 was 45 mV, the average physical semi-pore size Rp of the textile was 1 μm, and the porosity ρ of the textile was 50%.

[0098] Example 2B

[0099] A method for filtering gel particles in nuclear power plant water, using the PA-based filter material for filtering gel particles in nuclear power plant water prepared in Example 2A;

[0100] The average physical radius rp of the gel particles in the target removed nuclear power plant water is 0.2 μm, the Zeta potential Ub2 of the gel particles in the target removed nuclear power plant water is -5 mV, and the apparent flow velocity Vs of the nuclear power plant water is 0.667 mm / s.

[0101] The tests showed that the final rejection rate of gel particles in the target nuclear power plant water was 95.7%.

[0102] Example 3A

[0103] The preparation method of PA-based filter material for filtering gel particles from nuclear power plant water includes the following specific steps:

[0104] (1) Prepare raw materials;

[0105] PA substrate: PA meltblown nonwoven fabric; PA is PA6, and the PA molecular weight is 30kDa;

[0106] Acid solution: solute is phosphoric acid, pH value is 1.0, solvent is water;

[0107] PEI solution: concentration 5.0 wt%, solute PEI is hyperbranched polyethyleneimine, molecular weight M is 3 kDa, solvent is water;

[0108] (2) PA substrate activation;

[0109] The PA substrate was immersed in an acid solution at 95°C for 120 min, then washed with water and dried to obtain the activated PA substrate; wherein the mass ratio of PA substrate to acid solution was 1:20.

[0110] (3) Surface grafting of PEI;

[0111] The activated PA substrate was immersed in a PEI solution at 40°C for 120 min, wherein the mass ratio of the activated PA substrate to the PEI solution was 1:10. After washing and drying, a textile composed of PA fibers surface-grafted with PEI was obtained, which is a PA-based filter material used to remove gel particles from nuclear power plant water. The diameter of the PEI-grafted PA fibers is 6 μm, and the weight of the textile is 30 g / m². 2 The bubble point flow rate was 0.003 L / min, the Zeta potential Ub1 of the textile at pH=7 was 33 mV, the average physical semi-pore size Rp of the textile was 1.5 μm, and the porosity ρ of the textile was 65%.

[0112] Example 3B

[0113] A method for filtering gel particles in nuclear power plant water, using the PA-based filter material for filtering gel particles in nuclear power plant water prepared in Example 3A;

[0114] The average physical radius rp of the gel particles in the target removed nuclear power plant water is 1 μm, the Zeta potential Ub2 of the gel particles in the target removed nuclear power plant water is -10 mV, and the apparent flow velocity Vs of the nuclear power plant water is 1.000 mm / s.

[0115] The test results showed that the final rejection rate of gel particles in the target nuclear power plant water was 95.1%.

[0116] Example 4A

[0117] The preparation method of PA-based filter material for filtering gel particles from nuclear power plant water includes the following specific steps:

[0118] (1) Prepare raw materials;

[0119] PA resin: PA is PA66, with a molecular weight of 15kDa;

[0120] Acid solution: solute is acetic acid, pH value is 1.0, solvent is water;

[0121] PEI solution: concentration 0.5wt%, solute PEI is hyperbranched polyethyleneimine, molecular weight M is 70kD, solvent is water;

[0122] Organic solvent: hexafluoroisopropanol;

[0123] (2) PA resin pulverization;

[0124] The average particle size of the PA resin after pulverization is 200 mesh.

[0125] (3) Activation;

[0126] The pulverized PA resin was immersed in an acid solution at 95°C for 120 minutes, then washed with water and dried; the mass ratio of PA to acid solution was 1:20.

[0127] (4) Surface grafting of PEI;

[0128] The activated PA resin was immersed in PEI solution at 40°C for 120 min, then washed with water and dried; the mass ratio of the activated PA resin to PEI solution was 1:5.

[0129] (5) Prepare the spinning solution;

[0130] The PA resin grafted with PEI was dissolved in an organic solvent, and the concentration of the spinning solution was 5 wt%.

[0131] (6) Electrospinning;

[0132] The spinning solution was electrospun using the following parameters: spinning voltage 30kV, receiving distance 10cm, and spinning speed 1mL / min. This yielded a textile composed of PA fibers surface-grafted with PEI, which is used as a PA-based filter material for removing gel particles from nuclear power plant water. The diameter of the PEI-grafted PA fibers is 15μm, and the weight of the textile is 15g / m³. 2 The bubble point flow rate was 0.03 L / min, the Zeta potential Ub1 of the textile at pH=7 was 20 mV, the average physical semi-pore size Rp of the textile was 0.8 μm, and the porosity ρ of the textile was 60%.

[0133] Example 4B

[0134] A method for filtering gel particles in nuclear power plant water, using the PA-based filter material for filtering gel particles in nuclear power plant water prepared in Example 4A;

[0135] The average physical radius rp of the gel particles in the target removed nuclear power plant water is 0.05 μm, the Zeta potential Ub2 of the gel particles in the target removed nuclear power plant water is -15 mV, and the apparent flow velocity Vs of the nuclear power plant water is 0.333 mm / s.

[0136] The tests showed that the final rejection rate of gel particles in the target nuclear power plant water was 99.9%.

[0137] Example 5A

[0138] The preparation method of PA-based filter material for filtering gel particles from nuclear power plant water includes the following specific steps:

[0139] (1) Prepare raw materials;

[0140] PA resin: PA is PA6, with a molecular weight of 30kDa;

[0141] Acid solution: solute is citric acid, pH value is 3.0, solvent is water;

[0142] PEI solution: concentration 5.0 wt%, solute PEI is hyperbranched polyethyleneimine, molecular weight M is 70 kD, solvent is water;

[0143] Organic solvent: hexafluoroisopropanol;

[0144] (2) PA resin pulverization;

[0145] The average particle size of the PA resin after pulverization is 1000 mesh;

[0146] (3) Activation;

[0147] The pulverized PA resin was immersed in an acid solution at 40°C for 15 minutes, then washed with water and dried; the mass ratio of PA to acid solution was 1:10.

[0148] (4) Surface grafting of PEI;

[0149] The activated PA resin was immersed in PEI solution at 95°C for 15 minutes, then washed with water and dried; the mass ratio of the activated PA resin to PEI solution was 1:10.

[0150] (5) Prepare the spinning solution;

[0151] The PA resin grafted with PEI was dissolved in an organic solvent, and the concentration of the spinning solution was 25 wt%.

[0152] (6) Electrospinning;

[0153] The spinning solution was electrospun using the following parameters: spinning voltage 15kV, receiving distance 30cm, and spinning speed 0.01mL / min. This yielded a textile composed of PA fibers surface-grafted with PEI, which is used as a PA-based filter material for removing gel particles from nuclear power plant water. The diameter of the PEI-grafted PA fibers is 0.1μm, and the textile's basis weight is 100g / m². 2 The bubble point flow rate was 0.003 L / min, the Zeta potential Ub1 of the textile at pH=7 was 45 mV, the average physical semi-pore size Rp of the textile was 6.1 μm, and the porosity ρ of the textile was 75%.

[0154] Example 5B

[0155] A method for filtering gel particles in nuclear power plant water, using the PA-based filter material for filtering gel particles in nuclear power plant water prepared in Example 5A;

[0156] The average physical radius rp of the gel particles in the target removed nuclear power plant water is 5 μm, the Zeta potential Ub2 of the gel particles in the target removed nuclear power plant water is -15 mV, and the apparent flow velocity Vs of the nuclear power plant water is 1.000 mm / s.

[0157] The test results showed that the final rejection rate of gel particles in the target nuclear power plant water was 97.9%.

Claims

1. A PA-based filter material for filtering out gel particles in nuclear power plant water, characterized in that, This is a textile composed of PA fibers with PEI grafted onto the surface, where PEI is hyperbranched polyethyleneimine; The molecular weight M of PEI, the Zeta potential Ub1 of the textile at pH=7, the average physical half-pore size Rp of the textile, the porosity ρ of the textile, the average physical radius rp of the gel particles in the target-removed nuclear power plant water, the Zeta potential Ub2 of the gel particles in the target-removed nuclear power plant water, and the apparent flow rate Vs of the nuclear power plant water satisfy the following relationship: (rp×(1-0.2(Vs / ρ / Ka)))≥0.729(Rp-(kb2×kb1×((Ub1-Ub2)^0.19)×(Km^1 / 3)×β^0.2)); In the formula, the unit of rp is μm; The unit of Vs is mm / s; The value of Ka is 2, and the unit is mm / s; The unit of Rp is μm; kb2 is related to Vs / ρ. When Vs / ρ>5mm / s, kb2=0, and when Vs / ρ≤5mm / s, kb2=1. The value of kb1 is 0.019, and the unit is μm×(mv^-0.19)×(Da^-1 / 3); The unit of Ub1 is mV; The unit of Ub2 is mV; Km is related to the molecular weight M of PEI. When M≤70000Da, Km=M, and when M>70000Da, Km=70000Da. β is related to Vs, ρ, and Kv. If Vs / ρ≥Kv, then β=0; otherwise, β=1-Vs / ρ / Kv. The value of Kv is 5, and the unit is mm / s.

2. The PA-based filter material for removing gel particles from nuclear power plant water according to claim 1, characterized in that, The molecular weight M of PEI is 3k-100kDa, the Zeta potential Ub1 of the textile at pH=7 is 20-58mV, the average physical semi-pore size Rp of the textile is 0.1-6.1μm, the porosity ρ of the textile is 30-75%, the average physical radius rp of the gel particles in the target removed nuclear power plant water is 0.05-5μm, the Zeta potential Ub2 of the gel particles in the target removed nuclear power plant water does not exceed -5mV, and the apparent flow rate Vs of the nuclear power plant water is 0.333-1.000mm / s.

3. The PA-based filter material for removing gel particles from nuclear power plant water according to claim 2, characterized in that, The rejection rate of gel particles in the target nuclear power plant water is up to 99.0%.

4. The PA-based filter material for filtering gel particles in nuclear power plant water according to claim 1, characterized in that, The diameter of PA fibers grafted with PEI is 0.1-15μm; the weight of textiles is 15-200g / m². 2 The bubble point flow rate is 0.003-0.03 L / min.

5. The PA-based filter material for removing gel particles from nuclear power plant water according to claim 1, characterized in that, PA fiber is made from PA6 or PA66 with a molecular weight of 15k-30kDa.

6. The PA-based filter material for removing gel particles from nuclear power plant water according to claim 1, characterized in that, The manufacturing process of textiles is as follows: PA substrate activation → PEI surface grafting; The PA substrate is PA meltblown nonwoven fabric or PA electrospun nanofiber membrane. PA substrate activation involves acid hydrolysis of the PA substrate to form more carboxyl groups. Surface grafting of PEI involves grafting PEI onto the surface of an activated PA substrate.

7. The PA-based filter material for removing gel particles from nuclear power plant water according to claim 6, characterized in that, The specific process for activating PA substrate is as follows: the PA substrate is immersed in an acid solution at 40-95℃ for 15-120 minutes, then washed with water and dried. The pH value of the acid solution is 1.0-3.0, and the acid in the acid solution is one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, acetic acid and citric acid. The mass ratio of PA substrate to acid solution is 1:5-10. The specific process of surface grafting PEI is as follows: the activated PA substrate is immersed in PEI solution at 40-95℃ for 15-120 min, then washed with water and dried. The concentration of PEI solution is 0.5-5.0 wt%, and the mass ratio of activated PA substrate to PEI solution is 1:5-10.

8. The PA-based filter material for removing gel particles from nuclear power plant water according to claim 1, characterized in that, The manufacturing process of textiles is as follows: PA resin pulverization → activation → surface grafting of PEI → preparation of spinning solution → electrospinning; Activation involves acid hydrolysis of the pulverized PA resin to form more carboxyl groups. Surface grafting of PEI involves grafting PEI onto the surface of activated PA resin. The spinning solution is prepared by dissolving the PA resin with PEI grafted onto its surface in an organic solvent.

9. The PA-based filter material for removing gel particles from nuclear power plant water according to claim 8, characterized in that, The particle size of the pulverized PA resin is 200-1000 mesh; The specific activation process is as follows: the pulverized PA resin is immersed in an acid solution at 40-95℃ for 15-120 minutes, then washed with water and dried. The pH value of the acid solution is 1.0-3.0, and the acid in the acid solution is one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, acetic acid and citric acid. The specific process for surface grafting PEI is as follows: the activated PA resin is immersed in a PEI solution at 40-95℃ for 15-120 minutes, then washed with water and dried. The concentration of the PEI solution is 0.5-5.0 wt%. The organic solvent is hexafluoroisopropanol, and the concentration of the spinning solution is 5-25 wt%. The process parameters for electrospinning include: spinning voltage 15-30kV, receiving distance 10-30cm, and spinning speed 0.01-1mL / min.