A high-flux dry-stored composite nanofiltration membrane with fibrous surface structure and a preparation method thereof

Abstract

The application provides a high-flux dry storage type composite nanofiltration membrane with a fibrous surface structure and a preparation method thereof, selects a nylon microfiltration membrane as a base film, carries out cleaning and drying treatment on the base film, loads non-modified or non-reactive functional group modified nanoparticles on the nylon microfiltration membrane, synthesizes a polyamide separation layer on the nylon microfiltration membrane loaded with the nanoparticles by using an interfacial polymerization method, obtains a dry composite nanofiltration membrane before drying, and then carries out cleaning and drying to obtain the high-flux dry storage type composite nanofiltration membrane with the fibrous surface structure. The non-reactive nanoparticles are selected, the complicated processes such as coating and group modification are effectively avoided, the movement of the nanoparticles at the interface of two phases is utilized to improve the effective filtration area of the polyamide separation layer, the permeability is improved while the separation effect is ensured, the dry storage can be achieved without using a protective agent, and the shelf life of the membrane material is prolonged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of membrane separation technology, and particularly relates to a high-flux dry storage type composite nanofiltration membrane with a fibrous surface structure and a preparation method thereof. BACKGROUND

[0002] The performance of a nanofiltration membrane is between that of an ultrafiltration membrane and a reverse osmosis membrane, the molecular weight cut-off (MWCO) is 200-1000 g / mol, and the pore size is 0.5-2.0 nm, which can be used in the fields of seawater desalination, ion separation, wastewater reuse and drinking water purification. As a pressure-driven membrane material, the nanofiltration membrane realizes the separation of target substances by relying on the pressure difference between the two sides of the membrane during operation. Therefore, improving the flux of the nanofiltration membrane is conducive to reducing the energy consumption and operation cost. For this reason, many researchers in the field of membrane technology have devoted themselves to improving the permeability or separation of the membrane material in order to break through the "trade-off" effect between the permeability and selectivity of the membrane material.

[0003] At present, a preparation method of a high-surface roughness nanofiltration membrane material is disclosed in the prior art: first, a polymer nanofiber is used as an intermediate layer to be sprayed on the surface of a substrate to obtain a surface profile with high and low undulations; then, a polyamide separation layer is prepared by an interfacial polymerization process on this basis to obtain a nanofiltration membrane with high surface roughness. By increasing the effective permeation area of the nanofiltration membrane, the permeability of the membrane can be effectively improved. However, the improvement effect of this method on the performance of the nanofiltration membrane is limited by the diameter variation of the nanofiber, the spraying thickness and other parameters, and therefore the preparation conditions are required to be higher.

[0004] In recent years, dry storage type membrane materials have begun to attract attention due to their advantages of long-term storage without the use of protective agents and light weight for transportation. In 2020, the well-known enterprise Dow first launched a dry membrane element in the field of membrane materials. Subsequently, a research team disclosed a preparation method of a dry storage type composite nanofiltration membrane, which can prepare a nanofiltration membrane with stable performance before and after drying on a PTFE microfiltration membrane. However, the limitation of this method is that after soaking in an aqueous solution, two interfacial polymerization reactions are continuously carried out, so it is difficult to optimize the structure of the separation layer, resulting in a nanofiltration membrane with a flux of only 21.7-23.3 L / (m 2 ·h·bar).

[0005] Therefore, it has become a research direction to prepare a dry storage type nanofiltration membrane with high flux and good separation effect. SUMMARY

[0006] In view of this, the present application aims to at least partially solve one of the problems in the related art, and for this purpose, the present application provides a high-flux dry storage type composite nanofiltration membrane with a fibrous surface structure and a preparation method thereof, which improves the water permeability of the high-flux dry storage type composite nanofiltration membrane and thus improves the working efficiency of the high-flux dry storage type composite nanofiltration membrane under the premise of ensuring the separation effect.

[0007] To achieve the above-mentioned purposes, the technical scheme of the present application is as follows:

[0008] A preparation method of a high-flux dry storage type composite nanofiltration membrane with a fibrous surface structure, comprising the following steps:

[0009] 1) Selecting a nylon microfiltration membrane as a base film, and performing cleaning and drying treatment on the base film;

[0010] 2) Loading nanoparticles that are not modified or modified by non-reactive functional groups on the nylon microfiltration membrane treated in step 1);

[0011] 3) Preparing an aqueous phase solution A containing a polyamine aqueous phase monomer and an organic phase solution B containing a polyacyl chloride organic phase monomer;

[0012] 4) Using an interfacial polymerization method to synthesize a polyamide separation layer on the nylon microfiltration membrane loaded with nanoparticles in step 2), i.e. a composite nanofiltration membrane before drying;

[0013] 5) Performing cleaning and drying on the composite nanofiltration membrane before drying obtained in step 4) to obtain a composite nanofiltration membrane after drying, i.e. a high-flux dry storage type composite nanofiltration membrane with a fibrous surface structure.

[0014] Further, the nanoparticles in step 2) are at least one of titanium dioxide, calcium carbonate, metal-organic framework material, covalent organic framework material, and hydrotalcite intercalation material, and the average particle size of the nanoparticles is 30-300 nm.

[0015] Further, the interfacial polymerization method in step 4) is specifically as follows: fixing the nylon microfiltration membrane loaded with nanoparticles in a plate and frame mold, and making the side loaded with nanoparticles face up, then pouring the aqueous phase solution A into the plate and frame mold, so that the aqueous phase solution A completely immerses the surface of the nylon microfiltration membrane loaded with nanoparticles, and then pouring off the aqueous phase solution A and using a flexible rubber plate to remove the liquid droplets remaining on the membrane surface. Pouring the organic phase solution B into the plate and frame mold to perform interfacial polymerization reaction and form a polyamide separation layer on the nylon microfiltration membrane. After the reaction is completed, pouring off the organic phase solution B and washing the membrane surface with the organic phase solvent in the organic phase solution B to terminate the reaction, and then performing heat treatment to obtain the composite nanofiltration membrane before drying.

[0016] Further, the step 2) of dispersing the nanoparticles is loaded on the surface of the nylon microfiltration membrane by dispersing the nanoparticles in water to prepare a nanoparticle dispersion, and then by any of vacuum filtration, deposition, spraying, and spray printing, and the nanoparticle loading amount is 0.05-0.2 g / m 2 .

[0017] Further, the water phase solution A in the step 3) is composed of a polyamine water phase monomer, a water phase solvent, and an acid binding agent, the polyamine water phase monomer is at least one of piperazine, m-phenylenediamine, p-phenylenediamine, or melamine, the water phase solvent is ultrapure water, and the acid binding agent is at least one of sodium hydroxide, triethylamine, or sodium phosphate.

[0018] Further, the organic phase solution B in the step 3) is composed of a polyacyl chloride organic phase monomer and an organic phase solvent, the polyacyl chloride organic phase monomer is at least one of trimesoyl chloride, terephthaloyl chloride, or isophthaloyl chloride, and the organic phase solvent is at least one of n-hexane, cyclohexane, toluene, n-heptane, or n-octane.

[0019] Further, the concentration of the polyamine water phase monomer in the step 3) is 0.1-3.0% (w / v), the concentration of the polyacyl chloride organic phase monomer is 0.05-0.3% (w / v), and the concentration of the acid binding agent is 0.1-0.4% (w / v).

[0020] Further, the time for the water phase solution A to impregnate the surface of the nylon microfiltration membrane loaded with the nanoparticles is 10-600 s, and the reaction time is 10-600 s.

[0021] Further, the heat treatment temperature is 10-80℃, and the heat treatment time is 60-1200 s.

[0022] Further, the cleaning method of the nylon microfiltration membrane is any one of ethanol aqueous solution immersion cleaning, ultrapure water immersion cleaning, and high-pressure gas blowing, and the drying method is any one of natural air drying, vacuum drying, or freeze drying.

[0023] The application also provides a high-flux dry storage type composite nanofiltration membrane prepared by the above preparation method.

[0024] The high-flux dry storage composite nanofiltration membrane of the present application takes nylon microfiltration membrane as base membrane, and in the preparation, firstly, non-reactive nanoparticles, which are unmodified or modified by non-reactive functional groups, are loaded onto the surface of the nylon microfiltration membrane, and then a polyamide separation layer is synthesized on the surface of the nylon microfiltration membrane loaded with the nanoparticles through an interfacial polymerization process. In the interfacial polymerization process, the poor compatibility between inorganic materials and organic materials is utilized to form a large number of defects between the non-reactive nanoparticles and the nascent amide layer; at the same time, the interfacial turbulence caused by the heat release of the polycondensation reaction is utilized to "squeeze" the aqueous solution A in the pores of the base membrane from the defects through the nascent amide layer, so that the aqueous solution A enters the organic phase side in the form of "water column"; since these "water columns" can form additional water-oil interfaces with the organic phase solution B, a large number of hollow fiber-like structures exist on the surface of the finally generated polyamide separation layer, thereby achieving the purpose of improving the effective filtration area. In addition, the non-reactive nanoparticles are not anchored to the base membrane through covalent bonds, so they can move under the driving of the interfacial turbulence to form an unstable reaction platform, further increasing the number of defects on the nascent amide layer, thereby increasing the formation sites of the hollow fiber-like structures on the membrane surface.

[0025] Compared with the prior art, the high-flux dry storage composite nanofiltration membrane with fibrous surface structure and the preparation method thereof have the following advantages:

[0026] (1) The non-reactive nanoparticles are selected in the present application, which not only can effectively avoid complex processes such as wrapping and group modification, but also can utilize the movement of the nanoparticles at the interface of two phases to maximize the effective filtration area of the polyamide separation layer.

[0027] (2) By increasing the effective filtration area of the polyamide separation layer, the present application can improve the permeability of the nanofiltration membrane while ensuring its separation effect, thereby breaking the "trade-off" effect between the selectivity and permeability of the nanofiltration membrane.

[0028] (3) Compared with the nanofiltration membrane prepared by using unmodified nylon microfiltration membrane, the high-flux dry storage composite nanofiltration membrane prepared by the present application has an increase in pure water flux of more than 120%, and the rejection rate of Na2SO4 is more than 95%, and the permeability of the membrane is significantly improved.

[0029] (4) The high-flux dry storage composite nanofiltration membrane prepared by the method of the present application can be stored in dry state without the use of protective agents, which is beneficial to prolong the shelf life of the membrane material; at the same time, the dry high-flux dry storage composite nanofiltration membrane material has a relatively light weight, which is convenient for transportation and installation; in addition, the excellent selective permeability of the nanofiltration membrane material can also reduce the operating energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a scanning electron microscope image of the surface of the nylon microfiltration membrane.

[0031] Figure 2 A scanning electron microscope image of the surface of the nanofiltration membrane prepared for Comparative Example 1.

[0032] Figure 3 A transmission electron microscope image of the cross-section of the nanofiltration membrane prepared for Comparative Example 1.

[0033] Figure 4 A scanning electron microscope image of the surface of the nanofiltration membrane prepared for Comparative Example 2.

[0034] Figure 5 A transmission electron microscope image of the cross-section of the nanofiltration membrane prepared for Comparative Example 2.

[0035] Figure 6 A scanning electron microscope image of the surface of the nanofiltration membrane prepared for Example 1.

[0036] Figure 7 A transmission electron microscope image of the cross-section of the nanofiltration membrane prepared for Example 1.

[0037] Figure 8 A scanning electron microscope image of the surface of the nanofiltration membrane prepared for Example 2.

[0038] Figure 9 A scanning electron microscope image of the surface of the nanofiltration membrane prepared for Example 3. DETAILED DESCRIPTION

[0039] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which the present application belongs. The test reagents used in the following examples are all conventional biochemical reagents unless otherwise specified; and the experimental methods used are all conventional methods unless otherwise specified.

[0040] The present application will be described in detail below with reference to the examples and the accompanying drawings.

[0041] Example 1

[0042] 1) A nylon microfiltration membrane with an average pore size of 0.1 μm was selected as the base membrane, which was thoroughly cleaned with ultrapure water and naturally air-dried;

[0043] 2) 5 mg of titanium dioxide with a particle size of 100 nm was added to 100 ml of ultrapure water, and ultrasonic treatment was performed for 4 h to obtain a titanium dioxide dispersion liquid; the treated nylon microfiltration membrane in step 1) was placed on a vacuum filtration device, and the titanium dioxide dispersion liquid was poured onto the surface of the nylon microfiltration membrane and subjected to filtration, wherein the titanium dioxide nanoparticles were retained on the surface of the nylon microfiltration membrane, thereby achieving loading of the titanium dioxide nanoparticles on the surface of the nylon microfiltration membrane;

[0044] 3) Two solutions required for interfacial polymerization reaction were prepared, wherein aqueous phase solution A contained 1.0% (w / v) piperazine and 0.4% (w / v) sodium hydroxide with ultrapure water as aqueous phase solvent, and organic phase solution B contained 0.1% (w / v) trimesoyl chloride with n-hexane as organic phase solvent;

[0045] 4) A polyamide separation layer was synthesized on the nylon microfiltration membrane loaded with titanium dioxide nanoparticles in step 2) by using the interfacial polymerization method to obtain a composite nanofiltration membrane before drying;

[0046] The specific steps are as follows: first, pour the prepared aqueous phase solution A into the nylon base membrane loaded with titanium dioxide nanoparticles in step 2), immerse for 5 minutes, pour out the aqueous phase solution A, and scrape off the residual droplets on the surface with a flexible rubber plate. Then pour the prepared organic phase solution B, after 20s of reaction, pour out the organic phase solution B and wash the membrane surface with n-hexane to remove unreacted polyacyl chloride organic monomers on the membrane surface, terminate the reaction, and place the obtained membrane in a 50°C oven for 3min of heat treatment to further crosslink the polyamide separation layer. After heat treatment, the composite nanofiltration membrane before drying is obtained.

[0047] 5) The composite nanofiltration membrane before drying obtained in step 4) is thoroughly washed with ultrapure water, and is naturally air-dried at room temperature for 24h to obtain a composite nanofiltration membrane after drying, i.e., a high-flux dry storage type composite nanofiltration membrane with a fibrous surface structure.

[0048] Example 2

[0049] The difference between this example and Example 1 is that the titanium dioxide nanoparticles with a particle size of 100nm are replaced by calcium carbonate with a particle size of 30nm.

[0050] Example 3

[0051] The difference between this example and Example 1 is that the titanium dioxide nanoparticles with a particle size of 100nm are replaced by calcium carbonate with a particle size of 200nm.

[0052] Example 4

[0053] The difference between this example and Example 1 is that the amount of titanium dioxide added in 100mL of ultrapure water in step 2) is changed to 10mg.

[0054] Example 5

[0055] The difference between this example and Example 1 is that the concentration of piperazine contained in the aqueous phase solution A is changed to 2.0% (w / v), and the interfacial polymerization reaction time is changed to 15s.

[0056] Example 6

[0057] The difference between this example and Example 1 is that the concentration of sodium hydroxide contained in the aqueous phase solution A is changed to 0.1% (w / v).

[0058] Example 7

[0059] The difference between this example and Example 1 is that the concentration of the organic phase monomer trimesoyl chloride is changed to 0.05% (w / v) and the interfacial polymerization reaction time is changed to 30 s.

[0060] Example 8

[0061] The difference between this example and Example 1 is that the aqueous phase monomer piperazine is replaced by p-phenylenediamine.

[0062] Example 9

[0063] The difference between this example and Example 1 is that the sodium hydroxide contained in the aqueous phase solution A is replaced by triethylamine.

[0064] Example 10

[0065] The difference between this example and Example 1 is that the organic phase monomer trimesoyl chloride is replaced by p-phenylenediamine dichloride.

[0066] Example 11

[0067] The difference between this example and Example 1 is that the organic phase solvent in the organic phase solution B is replaced by cyclohexane.

[0068] Example 12

[0069] The difference between this example and Example 1 is that the base membrane is replaced by a polytetrafluoroethylene microfiltration membrane with a pore size of 0.1 μm.

[0070] The dry pre-composite nanofiltration membrane prepared in the above step 4) is a wet membrane, and the dry post-composite nanofiltration membrane obtained after cleaning and drying in step 5) is a dry membrane.

[0071] Comparative Example 1

[0072] A composite nanofiltration membrane is prepared on an unmodified nylon microfiltration membrane by an interfacial polymerization method.

[0073] 1) A nylon microfiltration membrane with an average pore size of 0.1 μm is selected as the base membrane, which is thoroughly cleaned with ultrapure water and naturally dried;

[0074] 2) An aqueous phase solution A containing 1.0% (w / v) piperazine and 0.4% (w / v) sodium hydroxide is prepared with ultrapure water as the aqueous phase solvent; an organic phase solution B of 0.1% (w / v) trimesoyl chloride is prepared with n-hexane as the organic phase solvent.

[0075] 3) Using the conventional interfacial polymerization method to prepare the polyamide composite nanofiltration membrane on the nylon microfiltration membrane, first pour the prepared aqueous phase solution A on the base film, soak for 5 minutes, pour off the aqueous phase solution A, and then use a flexible rubber plate to scrape off the excess liquid drops on the surface. Then, pour the prepared organic phase solution B, pour off the organic phase solution B after 20s and rinse the membrane surface with n-hexane solvent. Put the membrane into an oven for heat treatment at 50℃ for 3min to further crosslink the polyamide separation layer. After heat treatment, the composite nanofiltration membrane before drying is obtained;

[0076] 4) Use ultrapure water to thoroughly clean the nanofiltration membrane obtained in step 3), and then place it in a room temperature condition for natural air drying for 24h to obtain the dried composite nanofiltration membrane.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 1 is that the titanium dioxide in step 2) is replaced by polydopamine modified titanium dioxide nanoparticles. Other conditions are the same as Example 1.

[0079] The surface of the titanium dioxide nanoparticles is modified using polydopamine to change the titanium dioxide from non-reactive nanoparticles to reactive nanoparticles, and the operation process is as follows: weigh 0.5g of titanium dioxide with a particle size of 100nm into a conical flask containing 100mL of ultrapure water, ultrasonic dispersion for 6h; add 50mg of dopamine hydrochloride to the dispersion liquid, and stir at room temperature for 6h, then centrifuge at 8000rpm for 10min for solid-liquid separation; wash the obtained solid with ultrapure water for 3 times, and then vacuum dry at 50℃ for 24h to obtain polydopamine modified titanium dioxide nanoparticles. The modified titanium dioxide surface contains amine groups, which can react with acyl chloride to avoid the formation of a large number of defects between the nanoparticles and the nascent amide layer.

[0080] Performance detection:

[0081] Through the cross-flow filtration device, the performance test of pure water flux and salt retention rate of the membrane sample is carried out at water temperature 25℃, test pressure 5bar and membrane surface cross-flow flow rate 0.45m / s using pure water and 2000ppm Na2SO4 single salt aqueous solution. The test membrane samples include the dried and undried composite nanofiltration membranes in Examples 1-12 and Comparative Example 2, i.e. the membrane samples prepared from steps 4) and 5) thereof, and the dried and undried composite nanofiltration membranes in Comparative Example 1, i.e. the membrane samples prepared from steps 3) and 4) thereof. The calculation method of the pure water flux of the membrane sample is as formula (1):

[0082]

[0083] In the formula, J is the permeation flux, L / (m 2V is the permeate liquid volume, L; S is the test membrane area, m 2 ; At is the sampling time interval, h; P is the operating pressure, bar.

[0084] The calculation method of the Na2SO4 rejection rate of the membrane sample is shown in formula (2):

[0085]

[0086] In the formula, R is the Na2SO4 retention rate, %; C f and C p are the Na2SO4 concentrations in the raw water and the filtrate, respectively.

[0087] Table 1: Pure water flux and Na2SO4 rejection rate of different nanofiltration membranes

[0088]

[0089]

[0090] As can be seen from Table 1, after drying, the membrane samples prepared in the examples and the comparative examples do not have a large decrease in permeability or rejection, and exhibit excellent drying resistance.

[0091] The pure water permeation fluxes of the membrane samples in Examples 1-12 are significantly higher than those in Comparative Example 1, and the Na2SO4 rejection rates are equivalent to the rejection performance of the membrane samples in the comparative examples, both higher than 95%.

[0092] Among them, the membrane sample prepared by adding titanium dioxide nanoparticles in Example 1 has a pure water flux of 44.9 L / (m 2 ·h·bar) and 38.8 L / (m 2 ·h·bar) before and after drying, respectively, and the pure water fluxes are increased by 127% and 135% compared with the membrane sample without adding nanoparticles in Comparative Example 1. At the same time, the pure water flux of the membrane sample prepared in Example 1 is significantly higher than that in Comparative Example 2, indicating that the use of non-reactive nanoparticles to modify the porous base membrane according to the present application is more conducive to improving the permeability of the prepared nanofiltration membrane.

[0093] As shown in Figure 1 , the nylon microfiltration membrane surface has irregular crosslinking structures and large pores that are vertically and horizontally interlaced, and has a unique "up convex" and "down concave" morphology. After interfacial polymerization on the surface of the unmodified nylon microfiltration membrane, a relatively smooth polyamide separation layer is formed, and there are irregular wrinkle structures in some parts, as shown in Figure 2 , Figure 3 . According to Figure 4 , 5As shown, after interfacial polymerization on the surface of a nylon microfiltration membrane loaded with polydopamine-modified titanium dioxide (reactive) nanoparticles, the resulting composite nanofiltration membrane exhibits localized hill-like protrusions, but remains relatively smooth overall. According to... Figure 6 , 7 As shown, after interfacial polymerization on the surface of a nylon microfiltration membrane loaded with titanium dioxide (non-reactive) nanoparticles, a large number of fibrous structures growing towards the outer side of the membrane appear on the surface of the resulting polyamide separation layer, and these fibrous structures have cavities inside. The hollow fibrous structures can greatly increase the effective water-passing area of ​​the polyamide separation layer and improve the permeability of the composite nanofiltration membrane. Therefore, the high-flux dry-storage composite nanofiltration membrane with a fibrous surface structure prepared in this invention possesses excellent permeability.

[0094] The membrane samples prepared in Examples 2-4 were similar to those in Example 1 in terms of pure water flux and Na2SO4 rejection rate. Figure 6 , 8 As shown in Figures 9 and 1, the composite nanofiltration membranes prepared by loading different types or sizes of non-reactive nanoparticles onto the surface of nylon microfiltration membranes all exhibit a fibrous surface structure. This indicates that the type, size, and loading amount of nanoparticles can be freely interchanged within the scope defined by this invention.

[0095] The membrane samples prepared in Examples 5-12 had a pure water flux of 33.3 L / (m²) before and after drying. 2 ·h·bar)~45.1L / (m 2 The Na2SO4 rejection rate was 96.1%–97.6%, similar to the selective permeation capacity of Example 1. This indicates that the base membrane, aqueous monomer, acid-binding agent, organic monomer, and organic solvent can be freely substituted within the scope defined by this invention.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-flux dry-stored composite nanofiltration membrane having a fibrous surface structure, characterized by: The method comprises the following steps: 1) selecting a nylon microfiltration membrane as a base membrane, and cleaning and drying the base membrane; 2) loading non-modified or non-reactive functional group-modified nanoparticles on the nylon microfiltration membrane treated in step 1); 3) preparing an aqueous phase solution A containing polyamine aqueous phase monomers and an organic phase solution B containing polyacyl chloride organic phase monomers; 4) synthesizing a polyamide separation layer on the nylon microfiltration membrane loaded with nanoparticles in step 2) by an interfacial polymerization method, to obtain a dry pre-composite nanofiltration membrane; 5) cleaning and drying the dry pre-composite nanofiltration membrane obtained in step 4) to obtain a dry post-composite nanofiltration membrane, i.e., a high-flux dry storage composite nanofiltration membrane with a fibrous surface structure; The nanoparticles in step 2) are at least one of titanium dioxide, calcium carbonate, and hydrotalcite intercalation material, and the average particle size of the nanoparticles is 30-300 nm.

2. The method for preparing a high-flux dry-storage composite nanofiltration membrane with a fibrous surface structure according to claim 1, characterized in that: The interfacial polymerization method in step 4) is specifically performed as follows: pouring the aqueous phase solution A onto the surface of the nylon microfiltration membrane loaded with nanoparticles, and immersing the membrane, pouring off the aqueous phase solution A, then pouring the organic phase solution B onto the surface of the nylon microfiltration membrane immersed with the aqueous phase solution A, and performing an interfacial polymerization reaction, after the reaction is completed, pouring off the organic phase solution B and washing the membrane surface with an organic phase solvent in the organic phase solution B to terminate the reaction, and then performing a heat treatment, to obtain the dry pre-composite nanofiltration membrane.

3. The method for preparing a high-flux dry-storage composite nanofiltration membrane with a fibrous surface structure according to claim 1, characterized in that: The nanoparticles dispersed in the step 2) are loaded onto the surface of the nylon microfiltration membrane by dispersing the nanoparticles in water to prepare a nanoparticle dispersion, and then any of vacuum filtration, deposition, spray coating, and spray printing is implemented, and the nanoparticle loading amount is 0.05 ~ 0.2 g / m 2 .

4. The method for preparing a high-flux dry-storage composite nanofiltration membrane with a fibrous surface structure according to claim 1, characterized in that: The aqueous phase solution A in step 3) is composed of polyamine aqueous phase monomers, an aqueous phase solvent, and an acid-binding agent, the polyamine aqueous phase monomers are at least one of piperazine, m-phenylenediamine, p-phenylenediamine, or melamine, the aqueous phase solvent is ultrapure water, and the acid-binding agent is at least one of sodium hydroxide, triethylamine, or sodium phosphate.

5. The method for preparing a high-flux dry-storage composite nanofiltration membrane with a fibrous surface structure according to claim 1, characterized in that: The organic phase solution B in step 3) is composed of polyacyl chloride organic phase monomers and an organic phase solvent, the polyacyl chloride organic phase monomers are at least one of trimesoyl chloride, terephthaloyl chloride, or isophthaloyl chloride, and the organic phase solvent is at least one of n-hexane, cyclohexane, toluene, n-heptane, or n-octane.

6. The method for preparing a high-flux dry-storage composite nanofiltration membrane with a fibrous surface structure according to claim 4, characterized in that: The concentration of the polyamine aqueous phase monomers in step 3) is 0.1-3.0% (w / v), the concentration of the polyacyl chloride organic phase monomers is 0.05-0.3% (w / v), and the concentration of the acid-binding agent is 0.1-0.4% (w / v).

7. The method for preparing a high-flux dry-storage composite nanofiltration membrane with a fibrous surface structure according to claim 2, characterized in that: The time for immersing the surface of the nylon microfiltration membrane loaded with nanoparticles with the aqueous phase solution A is 10-600 s, and the reaction time is 10-600 s.

8. The method for preparing a high-flux dry-storage composite nanofiltration membrane with a fibrous surface structure according to claim 2, characterized in that: The heat treatment temperature is 10-80℃, and the heat treatment time is 60-1200 s.

9. The high-flux dry storage composite nanofiltration membrane prepared by the method according to any one of claims 1-8.

Images