Method for visualizing interfacial polymerization diffusion reaction process of nanofiltration membrane

Abstract

The invention provides a visualization method for a nanofiltration membrane interfacial polymerization diffusion reaction process. The method comprises the following steps: preparing a piperazine PI P solution, a trimesoyl chloride TMC solution and a dansyl chloride DNSCL solution with specified concentrations; the preparation method comprises the following steps: uniformly mixing a dansyl chloride DNSCL solution and a piperazine PI P solution; the dansyl chloride fluorescent agent is introduced on the basis of a special molecular structure of a water-phase monomer necessary for preparation of the nanofiltration membrane, and PI P is subjected to fluorescence labeling, so that the PI P has fluorescence characteristics and observability, and the problem that microcosmic observation cannot be performed on water-phase monomer molecules of the nanofiltration membrane at present is solved; based on the cover glass and the glass slide of special specifications, after special treatment, a reaction interface is created for observation of interfacial polymerization reaction, the problem that the two-phase monomer substance reaction interface of the nanofiltration membrane cannot be defined is solved, meanwhile, the observation position accuracy is greatly improved, and the situation that the reaction interface cannot be found during observation is prevented.

Description

Technical Field

[0001] The invention relates to a visualization method, in particular to a visualization method for a nanofiltration membrane interface polymerization diffusion reaction process, and belongs to the technical field of nanofiltration membrane preparation and membrane separation water treatment. Background Art

[0002] Nanofiltration membrane (Nanofiltration Membrane) is a membrane separation technology between reverse osmosis membrane and ultrafiltration membrane, with a pore size range of approximately 1 nanometer to several nanometers; nanofiltration membrane is mainly used in water treatment and liquid separation processes, and can effectively remove certain ions, organic molecules, bacteria, viruses and other impurities in water.

[0003] Nanofiltration membrane has become an economical and efficient membrane separation process that can effectively inhibit small molecules and multivalent ions, and shows great prospects in wastewater treatment, water softening and purification. As the current mainstream method for preparing nanofiltration membranes, interfacial polymerization is widely used in the preparation of various nanofiltration membranes. Its principle is to immerse the base membrane in an aqueous solution for a certain period of time, then remove the membrane to remove excess aqueous solution, and then immerse it in an organic solution to react and obtain a polyamide nanofiltration membrane. During the interfacial polymerization reaction, the aqueous phase monomer diffuses into the organic phase monomer, diffuses to the interface of the two phases, and reacts with the organic phase monomer.

[0004] A large number of studies have shown that the diffusion rate of aqueous monomers to organic monomers and the reaction rate between the two phases are the fundamental reasons that affect the membrane structure (membrane thickness, cross-linking degree, membrane pore size, etc.). Therefore, in-depth research on the interaction mechanism between the two phases of monomers, clarifying the influence of the diffusion and reaction behavior of the two phases of monomer molecules on the physical and chemical structure and performance of the membrane, and revealing the direct relationship of "mechanism-structure-performance" in the preparation of nanofiltration membranes by interfacial polymerization reactions are of great significance for the targeted construction of nanofiltration membranes with specific structures and separation targets.

[0005] However, in order to clarify the diffusion and reaction behaviors of the two-phase monomer molecules, it is necessary to observe the entire interfacial polymerization process. However, this microscopic molecular-level reaction occurring at the nanometer and sub-nanometer time and space scale is difficult to capture and monitor by conventional methods. The existing technical methods all use chemical characterization methods to indirectly characterize the diffusion and reaction behaviors of the two-phase monomer molecules, and there is no technology that can directly observe them in real time. Therefore, a visualization method for the interfacial polymerization diffusion reaction process of nanofiltration membranes is proposed. Summary of the invention

[0006] In view of this, the present invention provides a method for visualizing the interfacial polymerization diffusion reaction process of a nanofiltration membrane. The method uses a dansyl chloride fluorescent agent to fluorescently label the aqueous phase monomer (PIP) molecules so that they have fluorescent properties. The diffusion and reaction behaviors of the PIP molecules in the interfacial polymerization reaction process are directly observed through a spinning disk confocal microscope, thereby achieving real-time and dynamic visualization of the nanofiltration membrane interfacial polymerization reaction, so as to solve or alleviate the technical problems existing in the prior art and at least provide a beneficial choice.

[0007] The technical solution of the embodiment of the present invention is implemented as follows: A method for visualizing the interfacial polymerization diffusion reaction process of a nanofiltration membrane comprises the following steps:

[0008] S1, preparing piperazine PIP solution, trimesoyl chloride TMC solution and dansyl chloride DNSCL solution of specified concentrations;

[0009] S2, mixing the dansyl chloride DNSCL solution and the piperazine PIP solution, fluorescently labeling the piperazine PIP, and obtaining a PIP-DNSCL solution;

[0010] S3, selecting a cover glass, and covering it on a glass slide after treatment, so as to create a reaction interface for the labeled piperazine PIP and trimesoyl chloride TMC to undergo interfacial polymerization reaction;

[0011] S4. Set the relevant parameters of the microscope, and drip PIP-DNSCL solution and trimesoyl chloride TMC solution on both sides of the reaction interface respectively. Under the microscope, the diffusion movement of the fluorescently labeled molecules can be observed to visualize the polymerization diffusion reaction process at the nanofiltration membrane interface.

[0012] Further preferably, in S1, the piperazine PIP solution is an aqueous solution, the solute is piperazine PIP, the solvent is deionized water, and the concentration is 0.1wv%-0.2wv%;

[0013] The TMC solution of trimesoyl chloride is an organic phase solution, wherein the solute is TMC trimesoyl chloride, the solvent is n-hexane, and the concentration is 0.1wv%-0.2wv%;

[0014] The solute of the dansyl chloride DNSCL solution is dansyl chloride DNSCL, the solvent is n-hexane, and the concentration thereof is 0.05-0.1 wv%.

[0015] Further preferably, in S2, the volume ratio of the dansyl chloride DNSCL solution to the piperazine PIP solution is 10:1, the mixing container is a centrifuge tube, and the mixing equipment is a constant temperature shaker.

[0016] Further preferably, in S2, the mixing conditions are: temperature of 25-30°C, amplitude of 3mm, rotation speed of 60rpm, and time of 24-36h.

[0017] Further preferably, the fluorescent labeling is performed by fluorescently labeling piperazine PIP molecules with dansyl chloride DNSCL molecules to generate PIP-DNSCL.

[0018] Further preferably, in S3, the size of the cover glass is 50×26 mm, and the thickness is 0.13-0.17 mm; the size of the slide glass is 76×26 mm, and the thickness is ≤170 μm.

[0019] Further preferably, in S3, the cover glass is processed by cutting it at the midline of the long side of the cover glass to divide it into two cover glasses of the same size and symmetrical appearance.

[0020] Further preferably, the creating of the reaction interface is to cover one side of the glass slide with a cut cover glass to form a reaction interface between the cover glass and the glass slide.

[0021] Further preferably, in S4, the microscope adopts a medium rotating disk confocal microscope, and the specific parameters are set as follows: excitation wavelength is 405nm; emission wavelength is 520nm; magnification is 40×-100×; dwell time is 10ms-100ms; exposure time is 1ms-10ms; test temperature is 23-28°C; relative humidity is ≤70%.

[0022] Further preferably, in S4, the solution is added dropwise by using two syringes to draw 3-5 ml of the PIP-DNSCL solution and the trimesoyl chloride TMC solution respectively, and drop them on both sides of the reaction interface formed by the cover glass and the slide glass.

[0023] The method for visualizing the interfacial polymerization diffusion reaction process of a nanofiltration membrane according to the present invention is described in detail as follows (the temperature not specified below is performed at room temperature):

[0024] S11, taking a certain amount of piperazine P IP and deionized water, and preparing an aqueous solution with a mass percentage of 0.1wv%-0.2wv%;

[0025] S12, taking a certain amount of trimesoyl chloride TMC and n-hexane, and preparing an organic phase solution with a mass percentage of 0.1wv%-0.2wv%;

[0026] S13, taking a certain amount of dansyl chloride DNSCL and n-hexane, preparing a dansyl chloride solution with a mass percentage of 0.05-0.1wv%%;

[0027] S21, mix the prepared aqueous phase solution and the sulfonyl chloride solution in a centrifuge tube at a volume ratio of 10:1, and place it in a constant temperature shaker, set the amplitude to 3 mm, the speed to 60 rpm, and shake at 25-30°C for 24-36 hours;

[0028] S22, after the mixing and shaking is completed, the supernatant is taken out, and under the irradiation of a UV lamp with a wavelength of 365 nm, the mixed aqueous phase solution is observed to see whether there is fluorescence brightness to determine whether the piperazine PIP is successfully labeled;

[0029] S31, select a cover glass with a size of 50×26 mm and a thickness of 0.15 mm, and use a glass cutter to cut the cover glass at the midline of the long side to cut it into a cover glass with a size of 25×26 mm for subsequent use;

[0030] S32, select a glass slide with a size of 76×26 mm and a thickness of 150 μm, and cover the cut cover glass in the middle of the glass slide for subsequent use;

[0031] S41, set the spinning disk confocal microscope excitation wavelength to 405nm, emission wavelength to 520nm, magnification to 40×-100×, dwell time to 10ms-100ms, and exposure time to 24-36ms;

[0032] S42, turn on the spinning disk confocal microscope, place the prepared cover glass-slide under the microscope, and adjust the lens to the created reaction interface;

[0033] S43. Use two syringes to draw 3-5 ml of fluorescently labeled piperazine PIP solution and TMC solution respectively, and add them dropwise on both sides of the reaction interface formed by the cover glass and the slide. After adding, use a microscope to observe the diffusion movement and interfacial reaction of the fluorescently labeled piperazine PIP molecules in real time.

[0034] The embodiment of the present invention has the following advantages due to the adoption of the above technical solution:

[0035] 1. The present invention introduces dansyl chloride fluorescent agent based on the special molecular structure of the aqueous phase monomers required for the preparation of nanofiltration membranes, and fluorescently labels PIP so that it has fluorescent characteristics and observable properties, thereby solving the current problem of being unable to perform microscopic observation of the aqueous phase monomer molecules of nanofiltration membranes.

[0036] 2. The present invention is based on cover glass and slide glass of special specifications. After special treatment, a reaction interface is created for observing interfacial polymerization reactions, which solves the problem that the reaction interface of the two-phase monomer substances of the nanofiltration membrane cannot be defined. At the same time, it also greatly improves the accuracy of the observation position and prevents the reaction interface from being lost during observation.

[0037] The above summary is for illustrative purposes only and is not limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 This is a schematic diagram of the reaction between piperazine PIP and dansyl chloride DNSCL in the present invention;

[0040] Figure 2 Schematic diagram of the reaction interface between the cover glass and the slide glass of the present invention;

[0041] Figure 3 It is a schematic diagram of the dropwise addition positions of the PIP-DNSCL solution and the trimesoyl chloride TMC solution of the present invention;

[0042] Figure 4 The fluorescence effect and FT-IR test diagram of the PIP-DNSCL solution in Example 3 of the present invention;

[0043] Figure 5 This is a distribution change diagram of PIP-DNSCL and trimesoyl chloride TMC on both sides of the reaction interface in Example 3 of the present invention;

[0044] Figure 6 This is a comparison diagram of piperazine PIP after irradiation in the comparative example of the present invention;

[0045] Figure 7 This is a distribution change diagram of piperazine PIP and trimesoyl chloride TMC on both sides of the reaction interface in the comparative example of the present invention. DETAILED DESCRIPTION

[0046] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0047] It should be noted that the terms "first", "second", "symmetrical", "array", etc. are only used to distinguish between description and position description purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the definition of "first", "symmetrical", etc. can explicitly or implicitly include one or more of these features; similarly, when the number of certain features is not limited in the form of words such as "two" or "three", it should be noted that this feature also explicitly or implicitly includes one or more feature quantities.

[0048] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0049] Embodiment 1

[0050] like Figure 1-Figure 3 As shown, an embodiment of the present invention provides a method for visualizing the interfacial polymerization diffusion reaction process of a nanofiltration membrane, comprising the following steps (the following steps without temperature indication are all performed at room temperature):

[0051] S111, take 0.1g piperazine PIP and 100ml deionized water to prepare an aqueous solution with a mass percentage of 0.1wv%;

[0052] S112, taking 0.1 g of trimesoyl chloride TMC and 100 ml of n-hexane, preparing an organic phase solution with a mass percentage of 0.1 wv%;

[0053] S113, taking 0.05 g of dansyl chloride DNSCI and 100 ml of n-hexane, preparing a dansyl chloride solution with a mass percentage of 0.05 wv%;

[0054] S121, mix the prepared aqueous phase solution and the sulfuryl chloride solution in a centrifuge tube at a volume ratio of 10:1, and place the mixture in a constant temperature shaker, set the amplitude to 3 mm, the rotation speed to 60 rpm, and shake at 25°C for 36 h;

[0055] S122, after the mixing and shaking is completed, the supernatant is taken out and irradiated with ultraviolet light at a wavelength of 365 nm;

[0056] S131, select a cover glass with a size of 50×26 mm and a thickness of 0.15 mm, and use a glass cutter to cut the cover glass at the midline of the long side to cut it into a cover glass with a size of 25×26 mm for subsequent use;

[0057] S132, select a slide glass with a size of 76×26 mm and a thickness of 150 μm, and cover the cut cover glass in the middle of the slide glass for subsequent use, as follows: Figure 2 As shown;

[0058] S141. At room temperature, set the spinning disk confocal microscope to an excitation wavelength of 405 nm, an emission wavelength of 520 nm, a magnification of 40×, a dwell time of 10 ms, and an exposure time of 1 ms;

[0059] S142, turn on the spinning disk confocal microscope, place the prepared cover glass-slide under the microscope, and adjust the lens to the created reaction interface;

[0060] S143. Use two 5 ml syringes to draw 3 ml of fluorescently labeled PIP solution and TMC solution respectively, and drip them on both sides of the reaction interface formed by the cover glass and the slide. After dripping, use a microscope to observe the diffusion movement of fluorescently labeled PIP molecules and the interface reaction in real time.

[0061] Embodiment 2

[0062] like Figure 1-Figure 3 As shown, the embodiment of the present invention also provides a method for visualizing the process of nanofiltration membrane interface polymerization diffusion reaction, comprising the following steps (the following steps without temperature indication are all performed at room temperature):

[0063] S211, take 0.2 g of piperazine PIP and 100 ml of deionized water to prepare an aqueous solution with a mass percentage of 0.2 wv%;

[0064] S212, taking 0.2 g of trimesoyl chloride TMC and 100 ml of n-hexane, and preparing an organic phase solution with a mass percentage of 0.2 wv%;

[0065] S213, taking 0.1 g of dansyl chloride DNSC I and 100 ml of n-hexane, preparing a dansyl chloride solution with a mass percentage of 0.1 wv%;

[0066] S221, mix the prepared aqueous phase solution and sulfonyl chloride solution in a centrifuge tube at a volume ratio of 10:1, and place in a constant temperature shaker, set the amplitude to 3 mm, the speed to 60 rpm, and shake at 30°C for 36 hours;

[0067] S222, after the mixing and shaking is completed, take the supernatant and irradiate it under the condition of ultraviolet light with a wavelength of 365nm;

[0068] S231, select a cover glass with a size of 50×26 mm and a thickness of 0.15 mm, and use a glass cutter to cut the cover glass at the midline of the long side to cut it into a cover glass with a size of 25×26 mm for subsequent use;

[0069] S232, select a glass slide with a size of 76×26 mm and a thickness of 150 μm, and cover the cut cover glass in the middle of the glass slide for subsequent use;

[0070] S241. At room temperature, set the spinning disk confocal microscope with an excitation wavelength of 405 nm, an emission wavelength of 520 nm, a magnification of 100×, a dwell time of 100 ms, and an exposure time of 10 ms;

[0071] S242, turn on the spinning disk confocal microscope, place the prepared cover glass-slide under the microscope, and adjust the lens to the created reaction interface;

[0072] S243. Use two 5 ml syringes to draw 5 ml of fluorescently labeled PIP solution and TMC solution respectively, and drop them on both sides of the reaction interface formed by the cover glass and the slide. After dropping, use a microscope to observe the diffusion movement of fluorescently labeled PIP molecules and the interface reaction in real time.

[0073] Embodiment 3

[0074] like Figure 1-Figure 5 As shown, the embodiment of the present invention also provides a method for visualizing the process of nanofiltration membrane interface polymerization diffusion reaction, comprising the following steps (the following steps without temperature indication are all performed at room temperature):

[0075] S311, take 0.15g piperazine P IP and 100ml deionized water to prepare an aqueous solution with a mass percentage of 0.15wv%;

[0076] S312, taking 0.15 g of trimesoyl chloride TMC and 100 ml of n-hexane, preparing an organic phase solution with a mass percentage of 0.15 wv%;

[0077] S313, taking 0.075 g of dansyl chloride DNSCI and 100 ml of n-hexane, preparing a dansyl chloride solution with a mass percentage of 0.075 wv%;

[0078] S321, mix the prepared aqueous phase solution and the sulfonyl chloride solution in a centrifuge tube at a volume ratio of 10:1, and place the mixture in a constant temperature shaker, set the amplitude to 3 mm, the rotation speed to 60 rpm, and shake at 30°C for 30 h;

[0079] S322. After the mixing and shaking, take the supernatant and irradiate it under the condition of ultraviolet light with a wavelength of 365nm. The specific results are as follows: Figure 4 As shown in a, it can be seen that the labeled PIP (PIP-DNSCL) has fluorescence characteristics; at the same time, the FT-IR test of PIP before and after labeling is performed, and the results are as follows Figure 4As shown in B, in the infrared spectrum of PIP-DNSCI after labeling, we observed that the sharp peak near 3204.1cm-1 is attributed to the stretching vibration peak of NH in PIP monomer, and the characteristic peak near 1329.7cm-1 corresponds to the stretching vibration of CN in PIP monomer; and the peak at 1573.5cm-1 is attributed to the stretching vibration absorption peak of C=C skeleton of benzene ring in DNSCI, and the peak at 790.2cm-1 is attributed to the absorption peak of CH in DNSCI; and the stretching vibration absorption peak of O=S=O in DNSCI appears at 1052.4cm-1; the results show that PIP molecule has been successfully labeled as PIP-DNSCL by DNSCI;

[0080] S331, select a cover glass with a size of 50×26 mm and a thickness of 0.15 mm, and use a glass cutter to cut the cover glass at the midline of the long side to cut it into a cover glass with a size of 25×26 mm for subsequent use;

[0081] S332, select a slide glass with a size of 76×26 mm and a thickness of 150 μm, and cover the cut cover glass in the middle of the slide glass for subsequent use, as follows: Figure 2 As shown;

[0082] S341. At room temperature, set the spinning disk confocal microscope to an excitation wavelength of 405 nm, an emission wavelength of 520 nm, a magnification of 100×, a dwell time of 50 ms, and an exposure time of 10 ms;

[0083] S342, turn on the spinning disk confocal microscope, place the prepared cover glass-slide under the microscope, and adjust the lens to the created reaction interface;

[0084] S343, use two 5 ml syringes to draw 3-5 ml of fluorescently labeled PIP solution and TMC solution respectively, and drop them on both sides of the reaction interface formed by the cover glass and the slide (the specific drop position is as follows Figure 3 After the addition, the diffusion movement and interfacial reaction of the fluorescent labeled PIP molecules were observed in real time using a microscope;

[0085] S344, such as Figure 5As shown in the figure, the diffusion movement and interfacial reaction of the fluorescently labeled PIP molecules were successfully observed. It can be clearly seen that: before diffusion occurs (0ms), the distribution of PIP-DNSCL and TMC on both sides of the interface; further, with the diffusion movement of PIP molecules and the start of interfacial polymerization reaction, PIP molecules quickly diffuse and enrich at the interface (10ms) to react with TMC molecules, and as the reaction proceeds, they gradually diffuse to the inside of the TMC side to react, and finally generate a polyamide membrane with fluorescent properties (50ms).

[0086] Comparative Example

[0087] like Figure 6-Figure 7 As shown, for the visualization of PIP and interfacial polymerization without fluorescent labeling, the following steps without temperature indication were all carried out at room temperature:

[0088] S411, take 0.15g piperazine and 100ml deionized water, and prepare an aqueous solution with a mass percentage of 0.15wv%;

[0089] S412, take 0.15 g of trimesoyl chloride and 100 ml of n-hexane to prepare an organic phase solution with a mass percentage of 0.15 wv%;

[0090] S421, take a certain amount of aqueous solution, irradiate it under the condition of ultraviolet lamp with a wavelength of 365nm, and according to the result ( Figure 6 ) It can be seen that the PIP molecules without fluorescent labeling do not have the fluorescent properties and the property of being observed;

[0091] S431, select a cover glass with a size of 50×26 mm and a thickness of 0.15 mm, and use a glass cutter to cut the cover glass at the midline of the long side to cut it into a cover glass with a size of 25×26 mm for subsequent use;

[0092] S432, select a slide glass with a size of 76×26 mm and a thickness of 150 μm, and cover the cut cover glass in the middle of the slide glass for subsequent use, as follows: Figure 2 As shown;

[0093] S441. At room temperature, set the spinning disk confocal microscope to an excitation wavelength of 405 nm, an emission wavelength of 520 nm, a magnification of 100×, a dwell time of 50 ms, and an exposure time of 10 ms;

[0094] S442, turn on the spinning disk confocal microscope, place the prepared cover glass-slide under the microscope, and adjust the lens to the created reaction interface;

[0095] S443, use two 5 ml syringes to draw 3-5 ml of PIP solution and TMC solution respectively, and drop them on both sides of the reaction interface formed by the cover glass and the slide (the specific drop position is as follows Figure 3 After the addition, the diffusion movement of PIP molecules and the interface reaction were observed in real time using a microscope;

[0096] like Figure 7 As shown, the diffusion behavior and interfacial reaction of PIP molecules that were not fluorescently labeled were observed. During the entire process (0ms, 10ms, 50ms), no diffusion behavior of any PIP molecules was observed, and no interfacial polymerization reaction was observed.

[0097] In summary, by comparing the observation results of Example 3 and the comparative example, the visualization method of the nanofiltration membrane interfacial polymerization diffusion reaction process of the present invention can better visualize the nanofiltration membrane monomer interfacial polymerization reaction process, and can intuitively and in real time observe the diffusion behavior of the monomers and the degree of reaction during the whole process. Therefore, the present invention has a very ideal effect on the real-time and dynamic visualization characterization of the nanofiltration membrane interfacial polymerization reaction.

[0098] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of various changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for visualizing the process of nanofiltration membrane interface polymerization and diffusion reaction, characterized in that: The following steps are involved: S1, preparing piperazine PIP solution, trimesoyl chloride TMC solution and dansyl chloride DNSCL solution of specified concentrations; S2, mixing the dansyl chloride DNSCL solution and the piperazine PIP solution, fluorescently labeling the piperazine PIP, and obtaining a PIP-DNSCL solution; S3, selecting a cover glass, and covering it on a glass slide after treatment, so as to create a reaction interface for the labeled piperazine PIP and trimesoyl chloride TMC to undergo interfacial polymerization reaction; S4. Set the relevant parameters of the microscope, and drip PIP-DNSCL solution and trimesoyl chloride TMC solution on both sides of the reaction interface respectively. Under the microscope, the diffusion movement of the fluorescently labeled molecules can be observed to visualize the polymerization diffusion reaction process at the nanofiltration membrane interface.

2. The method for visualizing the nanofiltration membrane interface polymerization diffusion reaction process according to claim 1, characterized in that: In S1, the piperazine PIP solution is an aqueous phase solution, the solute is piperazine PIP, the solvent is deionized water, and the concentration is 0.1wv%-0.2wv%; The TMC solution of trimesoyl chloride is an organic phase solution, wherein the solute is TMC trimesoyl chloride, the solvent is n-hexane, and the concentration is 0.1wv%-0.2wv%; The solute of the dansyl chloride DNSCL solution is dansyl chloride DNSCL, the solvent is n-hexane, and the concentration thereof is 0.05-0.1 wv%.

3. The method for visualizing the nanofiltration membrane interface polymerization diffusion reaction process according to claim 1, characterized in that: In the S2, the volume ratio of the dansyl chloride DNSCL solution to the piperazine PIP solution is 10:1, the mixing container is a centrifuge tube, and the mixing equipment is a constant temperature shaker.

4. The method for visualizing the nanofiltration membrane interface polymerization diffusion reaction process according to claim 1, characterized in that: In S2, the mixing conditions are as follows: temperature of 25-30°C, amplitude of 3mm, rotation speed of 60rpm, and time of 24-36h.

5. The method for visualizing the nanofiltration membrane interface polymerization diffusion reaction process according to claim 1, characterized in that: The fluorescent labeling is to fluorescently label the piperazine PIP molecule by using the dansyl chloride DNSCL molecule to react and generate PIP-DNSCL.

6. The method for visualizing the nanofiltration membrane interface polymerization diffusion reaction process according to claim 1, characterized in that: In the S3, the size of the cover glass is 50×26 mm, and the thickness is 0.13-0.17 mm; the size of the slide glass is 76×26 mm, and the thickness is ≤170 μm.

7. The method for visualizing the nanofiltration membrane interface polymerization diffusion reaction process according to claim 1, characterized in that: In S3, the cover glass is processed by cutting it at the midline of the long side of the cover glass to divide it into two cover glasses of the same size and symmetrical appearance.

8. The method for visualizing the nanofiltration membrane interface polymerization diffusion reaction process according to claim 7, characterized in that: The reaction interface is created by covering one side of the glass slide with a cut cover glass to form a reaction interface between the cover glass and the glass slide.

9. The method for visualizing the nanofiltration membrane interface polymerization diffusion reaction process according to claim 1, characterized in that: In the S4, the microscope adopts a medium rotating disk confocal microscope, and the specific parameters are set as follows: excitation wavelength is 405nm; emission wavelength is 520nm; magnification is 40×-100×; dwell time is 10ms-100ms; exposure time is 1ms-10ms; test temperature is 23-28°C; relative humidity is ≤70%.

10. The method for visualizing the nanofiltration membrane interface polymerization diffusion reaction process according to claim 1, characterized in that: In S4, the solution is added dropwise as follows: 3-5 ml of PIP-DNSCL solution and trimesoyl chloride TMC solution are drawn by two syringes respectively, and then dropped on both sides of the reaction interface formed by the cover glass and the slide glass.

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