Water-soluble active compound with high cationic charge density as well as preparation method and application of water-soluble active compound

Abstract

The invention discloses a water-soluble high cationic charge density active compound as well as a preparation method and application thereof. The water-soluble high cationic charge density compound molecule is prepared from a silane coupling agent, polyethyleneimine and a glycidyl compound. The structure of the prepared product not only contains an active siloxane group, but also contains a quaternary ammonium salt cation group and a large number of amino groups. The siloxane active groups retained on the structure of the compound can be subjected to chemical grafting reaction with the porous filter material with reactive active groups on the surface, and can also be subjected to condensation reaction in the drying process to form a polymer, so that the surface of the grafted and modified porous filter material is endowed with lasting high cationic charge density. The modified filter material has excellent removal performance on nano plastic in water, has excellent antibacterial performance, and has wide application prospects in the field of water filtration.

Description

Technical Field

[0001] The invention relates to the field of organic chemistry and filtration and separation technology, and in particular to a water-soluble high cationic charge density active compound, a preparation method thereof and application of the compound in the field of water filtration and separation. Background Art

[0002] Micro-nano plastics have become a major environmental issue of global concern and have been listed as new pollutants. They are not only widely distributed in lakes, rivers and other water environments, but are also difficult to decompose and can persist in the environment for many years. As time goes by, pollution continues to worsen. Among them, nanoplastics (less than 1 micron) have been found to be harmful at the cellular and molecular levels, and have a great negative impact on the growth, development and reproduction of organisms. Micro-nano plastics can even break through the gastrointestinal cell barriers of the human body and enter the human body circulation, posing a great potential hazard to human health. Studies have also found that tap water and bottled water also contain micro-nano plastics, which can directly enter the human body. Therefore, the removal of micro-nano plastics in water has become a practical problem that urgently needs to be solved.

[0003] As an emerging pollutant, there is currently a lack of targeted removal methods in environmental water bodies and tap water. At present, typical micro-nano plastic treatment processes in water include traditional methods such as coagulation, sand filtration, adsorption and biological treatment. The above methods are difficult to effectively remove micro-nano plastics of smaller size; and the biological treatment process conditions are harsh and the cost is high. The membrane filtration method can effectively remove micro-nano plastics, but its removal mechanism is mainly the size exclusion effect driven by pressure difference. The biggest disadvantage is the problem of membrane contamination, which can easily lead to a rapid increase in the resistance of the filter membrane and a decrease in the membrane flux, affecting the working efficiency of the membrane and quickly failing. The porous filter material has an excellent pore structure, which can play an excellent filtering performance and the ability to accommodate pollutants. It has broad application prospects in the removal of nano plastics. Among them, the glass fiber filter material is a filter material prepared by a papermaking wet molding process using glass fiber and glass wool as raw materials. Compared with other filter materials, it has excellent filtration performance, uniform pore distribution, and high pollution holding capacity.

[0004] Studies have found that most micro-nano plastics in the environment are negatively charged, so the surface is constructed with a positive charge. The electrostatic interaction between the filter surface and the micro-nano plastics can improve the filtration performance of the filter material for micro-nano plastics. For example, the literature [Xia Xue, Li Guoping, Luo Jiyue, Ma Yiwen. Quaternary ammonium salt grafting to improve the surface Zeta potential of glass fiber membranes, Water Purification Technology, 2020, 39(03): 82-88] uses glass fiber membranes as the matrix, plasma treatment, and then uses antibacterial agents and tetraethyl silicate reagents to chemically graft organic silicon quaternary ammonium salts to prepare positively charged glass fiber membranes. However, this method requires two treatment processes, which is relatively complicated, and the maximum zeta potential of the treated filter material is only 27.35mV. Chinese patent CN116249581A "Positively charged filter material with excellent removal performance for charged particles and preparation method thereof" discloses that a polyamine compound is compounded with a cross-linking agent to treat the surface of a filter material to make it positively charged, and has the performance of selectively removing negatively charged organic / inorganic particles, heavy metal ions and pathogenic microorganisms in water. This method also requires multiple process steps, and the preparation of its modifier uses chemical solvents, and is not an environmentally friendly product.

[0005] In addition, water also contains a large number of bacterial microorganisms, which grow and reproduce on the filter material, causing the filter material to fail. Therefore, if the filter material can have good antibacterial properties, it can improve the performance and life of the filter material. From the above, it can be seen that modifying the filter material surface with high cationic charge density compounds to form a high positive charge performance is the key to achieving efficient removal of nano-microplastics.

[0006] Therefore, there is an urgent need to develop a technology and material with simple preparation process, low cost, environmental friendliness, good removal function for micro-nano plastics in water, and good antibacterial properties, which is of great significance to ensuring the safety of water environment and drinking water and protecting people's health. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the problems of large resistance and short life of existing membrane filter materials in removing nano plastic pollutants in water through surface filtration, and prepare a water-soluble high cationic charge density active compound and apply it to porous filter materials (such as glass fiber filter materials). First, by chemically modifying the surface of the glass fiber filter material and introducing a large number of cationic groups and amine groups, the glass fiber filter material is given a lasting high-density positive charge performance, and through electrostatic adsorption, the nano plastics in water can be efficiently removed; secondly, the prepared water-soluble high cationic charge density active compound contains reactive silanol groups in its molecular structure, which can not only undergo polycondensation reaction to form a macromolecular adhesive to enhance the glass fiber filter material, but also can undergo grafting reaction with the hydroxyl groups on the surface of the glass fiber to form a covalent bond, thereby further enhancing its binding force with the glass fiber substrate, so that its surface positive charge performance has persistence; finally, the cationic group in the molecular structure contains a quaternary ammonium salt group with excellent antibacterial performance, so the modified glass fiber filter material can also be given excellent antibacterial performance.

[0008] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0009] The present invention provides a water-soluble high cationic charge density active compound and applies it to a porous filter material containing active reaction groups on the surface, thereby giving it a durable high cationic charge density performance and having excellent removal performance for micro-nano plastics with a particle size of less than or equal to 1 μm in water.

[0010] The present invention provides a water-soluble high cationic charge density active compound, which is prepared by the following method:

[0011] Add polyethyleneimine to water in an amount of 10-20 times its mass, then add a glycidyl compound, raise the temperature to 60-70°C and react for 3-4 hours, then control the temperature at 70-75°C, continue to add a silane coupling agent, and continue to react for 2-4 hours to prepare the target water-soluble high cationic charge density active compound.

[0012] Preferably, the polyethyleneimine is a branched polyethyleneimine with a molecular weight of 1800-10000.

[0013] Preferably, the glycidyl compound is one of glycidyl trimethylammonium chloride, glycidyl triethylammonium chloride or glycidyl tripropylammonium chloride.

[0014] Preferably, the added mass of the glycidyl compound is 20-40 wt % of the polyethyleneimine.

[0015] Preferably, the silane coupling agent is a silane coupling agent containing an epoxy group at one end and a siloxane group at the other end. The epoxy group contained at one end of the silane coupling agent of the present invention can react with PEI to generate the target substance, and the siloxane group at the other end is hydrolyzed to become a silanol group, thereby reacting with the substrate and undergoing a condensation reaction.

[0016] Further preferably, the silane coupling agent is one of 3-glycidyloxypropyltrimethoxysilane (A-187), 3-(2,2-epoxypropylene)propyltriethoxysilane (A-1871), β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (A-186), and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane (A-1861).

[0017] Preferably, the added mass of the silane coupling agent is 25-45wt% of the polyethyleneimine.

[0018] The water-soluble high cationic charge density active compound obtained by the above preparation method contains both active siloxane groups and quaternary ammonium salt cationic groups and a large number of amine groups in its molecular structure. It is used to modify porous filter materials, which can give the filter materials long-lasting high-density positive charge performance, have a high efficiency in removing micro-nano plastics in water, and the modified filter materials have excellent antibacterial properties.

[0019] The present invention also provides a filter material modified based on the above-mentioned water-soluble high cationic charge density active compound, which is prepared by the following method:

[0020] The porous filter material having active groups on the surface that can react with silanol groups is immersed in the above-mentioned water-soluble high cationic charge density active compound, acid is added to adjust the pH to 4-5, soaked for 1-3 hours, then taken out and dried at 100-150°C to obtain a porous filter material having a water-soluble high cationic charge density active compound on the surface.

[0021] Preferably, the porous filter material having active groups that can react with silanol groups is a glass fiber filter material.

[0022] Preferably, the water-soluble high cationic charge density active compound is used in an amount of 5% to 7% by weight of the porous filter medium material.

[0023] The present invention adopts a simple two-step feeding method, and controls the ratio and molecular weight of various raw materials within an appropriate range, so as to prepare a target water-soluble high cationic charge density active compound, which can be applied to a modified glass fiber filter material to have good filtering effect on micro-nano plastics in water and has antibacterial performance. Firstly, by introducing a quaternary ammonium salt group into the PEI molecular structure, in addition to further improving the cationic density of PEI, the quaternary ammonium salt group also has an excellent antibacterial function, which can give the product excellent antibacterial performance; secondly, on the basis of the quaternary ammonium salt modified PEI product, further modification is continued by adding a silane coupling agent containing an epoxy group and a siloxane group, thereby introducing a siloxane group into the product structure; finally, the siloxane group can be hydrolyzed into an active hydroxyl group under appropriate acidic conditions, which can not only undergo a grafting reaction with the filter material surface, but also undergo a polycondensation reaction to form a polymer, thereby giving the filter material surface a lasting high cationic charge density, and achieving high filtration efficiency and excellent antibacterial performance for nano plastics. Although the principle is very simple, the inventors have repeatedly studied and tested the order of adding materials, material ratio, PEI molecular weight, etc., and found that: the order of introducing quaternary ammonium salt groups and introducing two modified materials containing epoxy groups and siloxane groups must be strictly in accordance with the order of "first introducing quaternary ammonium salt modification, then introducing silane coupling agent modification containing epoxy groups and siloxane groups". If the silane coupling agent is added for modification first, then due to the hydrolysis of the silane coupling agent siloxane group under high temperature environment to a certain extent, the prepared material is prone to flocculation and other unstable states. In addition, if the ratio of the two modified raw materials or the molecular weight of the PEI raw material is not appropriate, the obtained product is either insoluble in water and unstable, or the application performance is significantly deteriorated.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The water-soluble high cationic charge density active compound of the present invention is a water-based environmentally friendly compound, and the quaternary ammonium salt group and the amine group on the structure can give the compound a high positive charge density. In addition, the silanol group in the molecular structure is reactive, and can not only chemically bond with the porous material substrate, but also enhance its bonding force with the glass fiber substrate, so that its surface positive charge performance has persistence, and can also form a macromolecular adhesive by polycondensation reaction to play a reinforcing role on the glass fiber filter material. The quaternary ammonium salt group in the molecular structure has excellent antibacterial properties, which can give the modified glass fiber filter material excellent antibacterial properties, effectively control the growth and reproduction of microorganisms, and extend the service life of the filter material. The positively charged porous filter material prepared by the inventive method can achieve under relatively low resistance, and has efficient filtering ability for nano plastic pollutants with a particle size of less than or equal to 1 μm in water, and has a wide range of application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0027] Figure 1 The present invention is a schematic diagram of the preparation mechanism of the water-soluble high cationic density active compound and its surface modification process for glass fiber filter materials.

[0028] Figure 2 This is a structural design diagram of the filter material water filtration performance test bench of the present invention, wherein: 1-test tank; 2-high-speed stirrer; 3-thermometer; 4-stop valve; 5-coarse filter; 6-hydraulic pump; 7-throttle valve; 8-sampling valve; 9-flow meter; 10-pressure gauge; 11-pressure difference sensor; 12-filter material fixture; 13-liquid collecting tank.

[0029] Figure 3 SEM image of glass fiber base paper.

[0030] Figure 4 SEM image of filter material of Example 5.

[0031] Figure 5 SEM image of glass fiber filter material after product modification in Comparative Example 4. DETAILED DESCRIPTION

[0032] The following is a further description of a water-soluble high cationic charge density active compound and its preparation method and application with reference to specific examples. Those skilled in the art will appreciate that these examples are only used to illustrate the present invention, but the protection scope of the present invention is not limited thereto.

[0033] The experimental methods in the following examples are conventional methods unless otherwise specified. The raw materials, reagents, etc. used in the following examples are commercially available products unless otherwise specified.

[0034] The following examples illustrate the preparation method of the glass paper and the related testing methods:

[0035] Preparation of glass fiber base paper: 475-79 glass wool and chopped glass fiber were mixed in a mass ratio of 7:3, and deflaked by a deflaking machine at a speed of 10,000 revolutions, with pH controlled at 2.5-3.5 and a quantitative of 48±1 g / m 2 After being evenly dispersed, the slurry is poured into a former, and after being dehydrated and formed, it is dried on a flat plate to obtain a glass fiber filter paper. The average pore size of the glass fiber paper is measured to be 3.03μm.

[0036] The tensile strength test (including tensile strength before and after soaking in water) was carried out in accordance with GB / T12914-2018. The tensile strength and elongation at break of the glass fiber filter paper were tested using a tensile strength tester (model: CE062, L&W, Sweden). The sample was 100 mm long and 15 mm wide. The treated filter material was immersed in deionized water at room temperature for one month, then dried and re-measured to obtain the tensile strength of the glass fiber filter material as the strength performance after soaking in water.

[0037] Zeta potential test of glass fiber filter material (including zeta potential before and after soaking in water): Use a streaming potential method Zeta potential meter (model: SZP-06, German Mütek company) to test, dissolve the glass fiber filter material into slurry, and prepare it into 500ml solution, control the slurry concentration to be less than 4%, and test the surface charge of the glass fiber slurry. Soak the treated filter material in deionized water at room temperature for one month, then take it out and dry it, and then re-measure the potential of the glass fiber filter material as the zeta potential after soaking in water.

[0038] The antibacterial performance of the filter material (including the antibacterial performance before and after soaking in water) was tested by the oscillation method: 5 mL of bacterial solution with a concentration of 1×10 8 cfu / mL~5×10 8 cfu / mL of experimental bacterial solution (Staphylococcus aureus) was placed in a conical flask filled with 70mL of 0.03mol / L PBS buffer (2.84g disodium hydrogen phosphate, 1.36g potassium dihydrogen phosphate, 1000mL water), and 0.75g of the shredded filter material sample was added. The conical flask was placed on a constant temperature water bath shaker and cultured at (24±1)℃ at 150rpm for different times. After the specified time, the experimental mixture was diluted to an appropriate multiple with 0.03mol / L PBS buffer, transferred to nutrient agar medium, and cultured at (37±1)℃ for 24h before counting and calculating the antibacterial rate. The treated filter material was immersed in deionized water at room temperature for one month, then dried and the antibacterial performance of the glass fiber filter material was re-measured.

[0039] Filtration performance (filtration efficiency and resistance of nanoplastics) test: With reference to the European standard EN 13443-2 "Waterconditioning equipment inside buildings-mechanical filters", a filter material water filtration performance test bench was designed using the single-pass method and the corresponding test methods were specified. Figure 2 As shown, among which: 1-test tank; 2-high-speed agitator; 3-thermometer; 4-stop valve; 5-coarse filter; 6-hydraulic pump; 7-throttle valve; 8-sampling valve; 9-flow meter; 10-pressure gauge; 11-differential pressure sensor; 12-filter material fixture; 13-liquid collecting tank.

[0040] The experimental conditions for water filtration efficiency test are as follows: water flow rate is 75L / h, test time is 60min, test area is 78.5cm 2 The test medium is deionized water, and the pollutant is a polystyrene latex ball suspension with an average particle size of 300nm (that is, nano-scale plastic with a particle size of 0.3μm). The polystyrene latex ball suspension diluted to a particle concentration of about 20,000 / ml is passed through the filter material at a surface flow rate of 10cm / min. The number of experimental particles in the upstream and downstream of the filter paper sample is tested, and the water filtration efficiency of the filter material is calculated. Samples are taken at the upstream and downstream sampling ports every 10 minutes, and the filtration efficiency of the filter material is obtained by calculating the number of upstream and downstream particles. The test time is 1 hour. At the same time, the pressure difference at the beginning of the test and the resistance change during the test for 1h are recorded, expressed as the resistance increase value. The treated filter material is immersed in deionized water at room temperature for one month, then dried and re-measured. The filtration performance of the glass fiber filter material is the filtration performance of the filter material after soaking in water.

[0041] The purpose of the present invention is to prepare a water-soluble high cationic charge density active compound and apply it to a porous filter material containing active reactive groups on the surface. The water-soluble high cationic density active compound of the present invention is prepared by reacting polyethyleneimine of a suitable molecular weight with an appropriate amount of a silane coupling agent and a glycidyl compound. The molecular structure of the obtained product contains both active siloxane groups and quaternary ammonium salt cationic groups and a large number of amine groups. The preparation mechanism of the compound and its surface modification process for glass fiber filter materials are as follows: Figure 1 shown.

[0042] Examples 1 to 4 and Comparative Examples 1 to 7

[0043] Examples 1 to 4 and Comparative Examples 1 to 7 prepared an active compound with a high cationic charge density.

[0044] Examples 1 to 4 and Examples 1 to 6 are prepared according to the following steps: polyethyleneimine is added to 10-20 times the mass of water, and then a glycidyl quaternary ammonium salt compound is added, the temperature is raised to 65°C and reacted for 3 hours, the temperature is controlled at 73°C, a silane coupling agent is added, and the reaction is continued for 3 hours to prepare the target product.

[0045] The reaction raw materials and dosage ratios used in Comparative Example 7 are the same as those in Example 1, except that the reaction order of adding the silane coupling agent and the glycidyl quaternary ammonium salt compound is switched.

[0046] The ingredient list and product states of Examples 1 to 4 and Comparative Examples 1 to 7 are shown in Table 1:

[0047] Table 1 Ingredients and product status of Examples 1 to 4 and Comparative Examples 1 to 7

[0048]

[0049]

[0050] From the results in Table 1, it can be seen that within the scope of the present invention, the high cationic charge density active compounds prepared in Examples 1 to 4 are all clear and transparent, indicating that they have excellent water solubility and storage stability. The products of Comparative Examples 1 to 3 also have excellent water solubility and storage stability. In Comparative Example 4, floccules appear, which may be due to the fact that the addition ratio of the glycidyl compound in the system is too high, resulting in the instability of the compound structure; in Comparative Example 5, a white precipitate appears, which is due to the fact that the molecular weight of the polyethyleneimine used is too high, and the molecular weight of the high cationic charge density compound formed is too large, which ultimately leads to a decrease in the water solubility of the product, so the product precipitates a white precipitate; and in Comparative Example 6, floccules appear after being placed for 3 days, indicating that the product is unstable, which may be due to the fact that the proportion of the silane coupling agent used in the product is too high, which easily causes the product to continue to react during the storage process, thereby causing the instability of the system and the precipitation of floccules. In Comparative Example 7, since the silane coupling agent first modifies PEI with glycidyl trimethyl ammonium chloride, the siloxane group reacts for too long in a high temperature environment, and a certain degree of hydrolysis occurs in advance, resulting in the prepared material being prone to flocculation and other unstable states.

[0051] Examples 5 to 8 and Comparative Examples 8 to 11

[0052] Examples 5 to 8 and Comparative Examples 8 to 10 prepared a glass fiber filter material modified by a water-soluble high cationic charge density active compound, which was prepared by the following method:

[0053] The same mass of glass fiber base paper was immersed in the stable water-soluble high cationic charge density active compound prepared in Examples 1 to 4 and Comparative Examples 1 to 3, respectively, and the pH was adjusted to 4-5, and the mixture was immersed for 2 hours. The concentration of the water-soluble high cationic charge density active compound was controlled so that the amount of the compound applied to the filter material was within the range of 6±0.5% of the weight of the filter material, and Examples 5 to 8 and Comparative Examples 8 to 10 were obtained. In addition, a water filter membrane with a pore size of 3 μm (purchased from Haining Yibo Filter Equipment Factory) was selected as Comparative Example 11. The glass fiber base paper without modification was used as a blank control. Then, the tensile strength performance, ζ potential, 300nm nanoplastic filtration efficiency, filtration resistance increase value and antibacterial performance of Staphylococcus aureus before and after the filter material was immersed in water were tested, and the test results are shown in Table 2.

[0054] Table 2 Performance test of filter material before soaking in water

[0055]

[0056] Table 3 Performance test of filter material after soaking in water

[0057]

[0058]

[0059] From the test results of Table 2 and Table 3, it can be seen that within the scope of the present invention, after the glass fiber filter material is treated with the water-soluble high cationic charge density active compound prepared in Examples 1 to 4, the filter material samples Examples 5 to 8 obtained all have good tensile strength performance, and the surface zeta potential of the filter material changes from the negative charge before treatment to a higher positive charge state, further indicating that the obtained product has a high cationic charge density; the filtration efficiency of the treated filter material reaches about 97%, and after filtering for 1 hour, the resistance only rises to about 0.80 KPa. And after soaking in water for one month, the performance of the material is basically unchanged, indicating that the material prepared by the method of the present invention has excellent long-lasting application performance.

[0060] And in Comparative Example 8, due to the low ratio of the glycidyl compound containing quaternary ammonium salt group, on the one hand, the cationic density has been slightly decreased, so the zeta potential and the filtration efficiency are slightly low. In addition, due to the decline of the ratio of quaternary ammonium salt group, the antibacterial property of the filter material has been greatly decreased. In Comparative Example 9, due to the too small molecular weight of the polyethyleneimine used, the prepared compound is not obviously enhanced to the filter material strength after being applied to the filter material, resulting in the low strength of the filter material. In addition, the performance degradation of the filter material in various aspects after soaking in water is also more obvious. In Comparative Example 10, due to the too low addition of the silane coupling agent, the binding force with the fiber substrate and the interaction between the compounds are weak, so the strength performance of the material is poor, and the performance degradation after soaking in water is very obvious. And Comparative Example 11 uses traditional water filtration membrane material, and when its aperture is close to the aperture of glass fiber, its filtration efficiency is only about 15%, and after filtering for one hour, its resistance is improved more obviously, which further illustrates the advantage of the material prepared by the method of the present invention in water filtration. In terms of antibacterial performance, the filter materials of Examples 5 to 8 exhibited excellent antibacterial performance due to sufficient quaternary ammonium salt groups, with antibacterial rates of ≥99.9 and no decrease in antibacterial performance after soaking in water. Comparative Examples 8 to 11 had poor antibacterial performance, and the performance further decreased after soaking in water.

[0061] In addition, compared Figure 3 (Glass fiber base paper) and Figure 4 It can be seen from (Example 5 filter material) that the water-soluble high cationic charge density active compound modified filter material prepared within the scope of the present invention can be mainly concentrated on the fiber surface and fiber connection, without pore blocking, so it can maintain a good pore structure, maintain good filtration performance and improve the strength performance of the filter material. The product not within the scope of the present invention does not have good water solubility ( Figure 5 , Comparative Example 4 (material morphology after modification of the product), the modified filter material has obvious pore blocking phenomenon, which affects the filtering performance of the filter material.

[0062] The above embodiments are only preferred implementation modes of the present invention and are only used to explain the present invention rather than to limit the present invention. Any changes, substitutions, modifications, etc. made by those skilled in the art without departing from the spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a water-soluble high cationic charge density active compound, characterized in that: The method comprises the following preparation steps: Add polyethyleneimine into water, then add glycidyl compound, raise the temperature to 60-70°C and react for 3-4 hours, then control the temperature at 70-75°C, continue to add silane coupling agent, and continue to react for 2-4 hours to prepare the target water-soluble high cationic charge density active compound.

2. The method for preparing a water-soluble high cationic charge density active compound according to claim 1, characterized in that: The polyethyleneimine is a branched polyethyleneimine with a molecular weight of 1800-10000.

3. The method for preparing a water-soluble high cationic charge density active compound according to claim 1, characterized in that: The mass of water added is 10-20 times the mass of polyethyleneimine.

4. The method for preparing a water-soluble high cationic charge density active compound according to claim 1, characterized in that: The glycidyl compound is one of glycidyl trimethylammonium chloride, glycidyl triethylammonium chloride and glycidyl tripropylammonium chloride; the added mass of the glycidyl compound is 20-40wt% of the polyethyleneimine.

5. The method for preparing a water-soluble high cationic charge density active compound according to claim 1, characterized in that: The silane coupling agent is a silane coupling agent containing an epoxy group at one end and a siloxane group at the other end.

6. The method for preparing a water-soluble high cationic charge density active compound according to claim 5, characterized in that: The silane coupling agent is one of 3-glycidyloxypropyltrimethoxysilane, 3-(2,2-epoxypropylene)propyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

7. The method for preparing a water-soluble high cationic charge density active compound according to claim 1, characterized in that: The added mass of the silane coupling agent is 25-45wt% of the polyethyleneimine.

8. A water-soluble high cationic charge density active compound prepared by the preparation method according to any one of claims 1 to 7, characterized in that: Its molecular structure contains active siloxane groups, quaternary ammonium salt cationic groups and a large number of amino groups.

9. Use of the water-soluble high cationic charge density active compound according to claim 8 in the preparation of water filtration materials, characterized in that: The filter material modified by water-soluble high cationic charge density active compounds can be used to filter micro-nano plastics with a particle size of less than or equal to 1 μm in water.

10. The use according to claim 9, characterized in that: The preparation method of the filter material modified by the water-soluble high cationic charge density active compound is as follows: The porous filter material having active groups on the surface that can react with silanol groups is immersed in the water-soluble high cationic charge density active compound, the amount of the water-soluble high cationic charge density active compound is 5%-7% of the weight of the porous filter material, acid is added to adjust the pH to 4-5, soak for 1-3 hours, then take out and dry at 100-150°C to obtain.

Images