Polytrithiocarbonate composite membrane as well as preparation method and application thereof
Polytrithiocarbonate composite membranes were prepared by interfacial polymerization and reversible addition-fragmentation chain transfer polymerization, which solved the problems of insufficient permeation flux and stability of existing nanofiltration membranes and achieved high-efficiency salt separation performance and improved permeability.
Patent Information
- Application Number
- CN202511735851.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-25
- Publication Date
- 2026-01-13
AI Technical Summary
Existing nanofiltration membranes have shortcomings in terms of permeation flux and stability. Modification processes are complex and difficult to achieve precise modification, resulting in poor modification effects for commercial nanofiltration membranes.
Polytrithiocarbonate composite films were prepared by interfacial polymerization of trithiocarbonate salt solution and α,α''-dibromo-p-xylene organic solution. The films were then post-modified by reversible addition-fragmentation chain transfer polymerization using methacryloyloxyethyltrimethylammonium chloride, acrylic acid, or acrylamide as modifying monomers, combined with photocatalysts and reducing agents.
A nanofiltration membrane with high pure water flux and inorganic salt rejection rate was obtained, achieving precise modification of functional groups and improving membrane permeability and salt separation performance.
Smart Images
Figure CN121314397A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanofiltration membrane technology, specifically relating to a polytrithiocarbonate composite membrane, its preparation method, and its application. Background Technology
[0002] Membrane separation technology is a separation technology that uses selectively permeable membranes as the separation medium to separate or classify multi-component liquid and gas phases. Industrial membrane separation technologies are classified into microfiltration, ultrafiltration, nanofiltration, and reverse osmosis based on the pore size of the separation medium. Among them, the pore size of the separation membrane used in nanofiltration is usually between 1 and 10 nm. Based on the pressure-driven membrane separation process, it is mainly used for the removal of divalent and polyvalent ions. Currently, commonly used nanofiltration membranes mainly include polyamide nanofiltration membranes, polyester nanofiltration membranes, and polysulfide nanofiltration membranes. Most commercial nanofiltration membranes are prepared based on interfacial polymerization technology.
[0003] For example, interfacial polymerized polyamide nanofiltration membranes are typically based on an aqueous phase containing polyamines and an oil phase containing acyl chlorides, which undergo a polymerization reaction at the interface to form a polyamide functional layer. The reaction rate between polyamines and acyl chlorides is fast, resulting in a small spatial structure and dense membrane structure. However, this often leads to problems such as ultra-thickness, wide pore size distribution, and low permeation flux. While it has a high rejection rate for divalent ions, it is difficult to meet the permeation flux requirements in industry. Currently, the structure and permeation characteristics of polyamide membranes are usually adjusted by controlling the polyamines in the aqueous phase, such as reducing the number of functional groups or replacing them with polyamines with lower reactivity. In the process of realizing this invention, the inventors found that the prior art has at least the following problems: the above-mentioned improvement methods often make it difficult to achieve precise modification to obtain a complete ultrathin functional membrane, or the modified functional membrane has poor permeability and stability, the modification process is complex, and the preparation conditions are demanding. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a polytrithiocarbonate composite film, its preparation method and application, in order to address the shortcomings of the prior art.
[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:
[0006] On the one hand, a method for preparing a polytrithiocarbonate composite film is provided, comprising:
[0007] Provide trithiocarbonate salt phase solution and α,α''-dibromo-p-xylene organic phase solution;
[0008] The trithiocarbonate salt phase solution is used to wet the substrate film;
[0009] An organic phase solution of α,α''-dibromo-p-xylene was placed on a substrate membrane soaked in a trithiocarbonate salt phase solution, and interfacial polymerization was performed to obtain a polytrithiocarbonate composite membrane.
[0010] On another aspect, a post-modified polytrithiocarbonate composite film is provided, wherein the polytrithiocarbonate composite film prepared by the above-mentioned method is used as a chain transfer agent to mediate reversible addition-fragmentation chain transfer polymerization, thereby realizing the polymerization modification of the polytrithiocarbonate composite film by the modifying monomer; wherein the modifying monomer includes methacryloyloxyethyltrimethylammonium chloride, acrylic acid or acrylamide.
[0011] On another aspect, a method for preparing the above-mentioned post-modified polytrithiocarbonate composite film is provided, comprising: immersing the polytrithiocarbonate composite film in a solution containing a modifying monomer in the presence of a photocatalyst and a reducing agent, and irradiating it with blue light to polymerize it, thereby obtaining the post-modified polytrithiocarbonate composite film.
[0012] On the other hand, this invention provides an application of the polytrithiocarbonate composite membrane prepared by the above-mentioned method or the post-modified polytrithiocarbonate composite membrane in the field of separation.
[0013] Compared with the prior art, the present invention has the following advantages:
[0014] 1. A novel method for preparing a polytrithiocarbonate composite membrane is provided, which utilizes a clickable sulfur-bromine interfacial polymerization reaction to obtain a nanofiltration membrane with high pure water flux and inorganic salt rejection rate.
[0015] 2. Furthermore, the polytrithiocarbonate composite membrane of the present invention has tunable functional group characteristics. Based on its abundant trithiocarbonate groups, it can mediate reversible addition-fragmentation chain transfer polymerization to achieve post-modification of functional groups, thereby obtaining a post-modified polytrithiocarbonate composite membrane with improved permeability, which can achieve efficient purification of high salinity water.
[0016] 3. This invention provides a method for obtaining a post-modified polytrithiocarbonate composite membrane by using the above-mentioned polytrithiocarbonate composite membrane as a chain transfer agent and based on reversible addition-fragmentation chain transfer polymerization. By utilizing this post-modification strategy, the modification groups can be precisely modified on the polytrithiocarbonate composite membrane, thereby improving the membrane's permeability.
[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0018] Figure 1 This is a schematic flowchart of the preparation method of the modified polytrithiocarbonate composite film in Example 1;
[0019] Figure 2 This is a schematic diagram of the mechanism of the post-modification in Example 1;
[0020] Figure 3The infrared spectrum of the polytrithiocarbonate nanofiltration membrane in Example 1;
[0021] Figure 4 This is a schematic diagram of the XPS test results for the polytrithiocarbonate nanofiltration membrane in Example 1;
[0022] Figure 5 The infrared spectra of the modified polytrithiocarbonate composite films in Examples 1-3 are shown below.
[0023] Figure 6 This is a schematic diagram of the contact angle test results for the polytrithiocarbonate composite membrane (PTTC TFC) in Example 1;
[0024] Figure 7 This is a scanning electron microscope image of the polytrithiocarbonate composite membrane (PTTC TFC) from Example 1;
[0025] Figure 8 This is a schematic diagram showing the calculation results of the film quality changes before and after modification in each embodiment;
[0026] Figure 9 The images shown are cross-sectional scanning electron microscope (SEM) images of the modified polytrithiocarbonate composite films of Examples 1-3. Detailed Implementation
[0027] The technical solution will now be clearly and completely described with reference to the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0028] In the following description, the term "and / or" is used to describe the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. A and B can be singular or plural.
[0029] In the following description, the terms “including,” “containing,” “having,” and “containing” are open-ended terms, meaning that they include but are not limited to.
[0030] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0031] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0032] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this application. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0033] The technical principle employed in this invention is as follows: A novel clickable sulfur-bromine interfacial polymerization method is provided to obtain a polytrithiocarbonate composite membrane with high-purity water flux and inorganic salt rejection rate. Furthermore, using this polytrithiocarbonate composite membrane as a RAFT chain transfer agent, based on in-situ PET-RAFT polymerization, modifying monomers are inserted into the polytrithiocarbonate composite membrane to achieve post-modification, thereby endowing the polytrithiocarbonate composite membrane with enhanced permeability and salt separation performance.
[0034] On the one hand, a method for preparing a polytrithiocarbonate composite film is provided, comprising:
[0035] Provide trithiocarbonate salt phase solution and α,α''-dibromo-p-xylene organic phase solution;
[0036] The trithiocarbonate salt phase solution is used to wet the substrate film;
[0037] An organic phase solution of α,α''-dibromo-p-xylene was placed on a substrate membrane soaked in a trithiocarbonate salt phase solution, and interfacial polymerization was performed to obtain a polytrithiocarbonate composite membrane.
[0038] This invention uses trithiocarbonate as the aqueous phase component and α,α''-dibromo-p-xylene as the organic phase component. The aqueous phase solution is first impregnated, followed by the organic phase solution, and then the membrane is prepared by interfacial polymerization. The membrane material has high pure water flux and selective rejection rate of inorganic salts.
[0039] In some embodiments, the preparation method of the trithiocarbonate salt phase solution includes:
[0040] An aqueous solution of carbon disulfide, pentaerythritol tetrakis(3-mercaptopropionic acid), and tetraethylammonium hydroxide was used as the reactant system. The reactant system was reacted under stirring conditions to obtain a trithiocarbonate aqueous solution. The concentrations of both carbon disulfide and pentaerythritol tetrakis(3-mercaptopropionic acid) were 0.2–1.2 mmol / mL in the reactant system. The stirring reaction was a magnetic stirring reaction at room temperature for 12–48 h. In some preferred embodiments, the concentration of carbon disulfide in the reactant system was 1.1–1.2 mmol / mL, and the concentration of pentaerythritol tetrakis(3-mercaptopropionic acid) was 0.28–0.3 mmol / mL.
[0041] In some embodiments, the method for preparing the α,α''-dibromo-p-xylene organic phase solution includes:
[0042] Under room temperature ultrasonic conditions, α,α''-dibromo-p-xylene is dissolved in toluene to obtain an organic phase solution of α,α''-dibromo-p-xylene; the concentration of α,α''-dibromo-p-xylene in the organic phase solution is 0.01~4 wt%. In some preferred embodiments, the concentration of α,α''-dibromo-p-xylene in the organic phase solution is 0.02 wt%.
[0043] In some embodiments, wetting the substrate with the trithiocarbonate salt solution includes: immersing the substrate with the trithiocarbonate salt solution, allowing it to stand for 0-20 minutes, removing the residual trithiocarbonate salt solution on the surface of the membrane, and obtaining a substrate wetted with the trithiocarbonate salt solution; in some preferred embodiments, the standing time is 5-15 minutes.
[0044] In some embodiments, an α,α''-dibromo-p-xylene organic phase solution is placed on a substrate film impregnated with a trithiocarbonate salt phase solution, and interfacial polymerization is performed to obtain a polytrithiocarbonate composite film, specifically including:
[0045] The α,α''-dibromo-p-xylene organic phase solution is uniformly poured onto a substrate membrane impregnated with a trithiocarbonate salt phase solution. The membrane is allowed to stand at room temperature for 0-20 min, washed, and dried to obtain a polytrithiocarbonate composite membrane. In some preferred embodiments, the standing time at room temperature is 10-20 min.
[0046] In some embodiments, the base film is a PVDF film.
[0047] On the other hand, a post-modified polytrithiocarbonate composite film is provided, which mediates reversible addition-fragmentation chain transfer polymerization by using the polytrithiocarbonate composite film as a chain transfer agent to achieve polymerization modification of the polytrithiocarbonate composite film by modifying monomers; the modifying monomers include methacryloyloxyethyltrimethylammonium chloride (DMC), acrylic acid (AA) or acrylamide (AM); the polymerization modification is carried out under aerobic and visible light conditions.
[0048] This invention uses one of methacryloyloxyethyltrimethylammonium chloride, acrylic acid, and acrylamide as a modifying monomer, which can effectively achieve controlled free radical polymerization, control the molecular weight distribution, and obtain polymers with the target structure.
[0049] On another front, a method for preparing a post-modified polytrithiocarbonate composite film is provided, comprising: immersing the polytrithiocarbonate composite film in a solution containing a modifying monomer in the presence of a photocatalyst and a reducing agent, and then polymerizing it under blue light to obtain the post-modified polytrithiocarbonate composite film; in some embodiments, the molar ratio of the photocatalyst, reducing agent, and modifying monomer is 7.5 × 10⁻⁶. -4 :36.6:(10~35); The blue light wavelength is 460 nm, and the blue light irradiation time is 20 h.
[0050] This invention uses polytrithiocarbonate composite membrane as a chain transfer agent to successfully achieve post-modification of polytrithiocarbonate composite membrane, and prepares nanofiltration membrane with significantly improved pure water flux.
[0051] On the other hand, an application of the above-mentioned composite membrane in the field of separation is provided, including its application in separating wastewater containing inorganic salts.
[0052] Prior to the application for this invention, a series of experiments were conducted. Some of the experimental results are listed below to provide a more detailed description of the invention. The following is a detailed description in conjunction with the embodiments.
[0053] Example 1
[0054] This embodiment provides a method for preparing a post-modified polytrithiocarbonate composite film (PTTC), the process of which is shown in the figure below. Figure 1 As shown, it specifically includes:
[0055] Step 1: Preparation of aqueous solution (trithiocarbonate solution): A mixture of 0.04 mol carbon disulfide (CS2), 0.01 mol pentaerythritol tetrakis(3-mercaptopropionic acid) (PTMP), and 35 mL of 20% tetraethylammonium hydroxide aqueous solution was used as the reactant system. The reactant system was magnetically stirred at room temperature for 24 h to obtain the trithiocarbonate aqueous solution.
[0056] Step 2: Preparation of the organic phase solution (α,α''-dibromo-p-xylene solution): α,α''-dibromo-p-xylene was placed in toluene and sonicated at 25°C for 12 h to obtain an α,α''-dibromo-p-xylene solution; the concentration of α,α''-dibromo-p-xylene in the α,α''-dibromo-p-xylene solution was 0.02 wt%;
[0057] Step 3, preparation of the polytrithiocarbonate composite membrane, including:
[0058] Step 301: Soak a commercially available PVDF membrane in deionized water for 24 h, then fix it as a base membrane in a glass disc container with the membrane surface facing upwards. Add 10 mL of the trithiocarbonate aqueous solution described in Step 1 to the container to submerge the base membrane, let it stand for 10 min, and then remove the residual trithiocarbonate solution on the surface to obtain the base membrane after aqueous solution treatment; the PVDF membrane was purchased from Jinteng and has a pore size of 0.45 μm.
[0059] Step 302: Pour 10 mL of α,α''-dibromo-p-xylene solution evenly onto the substrate membrane after aqueous solution treatment, let it stand at room temperature for 15 min to complete the "clickable" IP reaction, then wash with water 3 times and dry to obtain a polytrithiocarbonate composite membrane (PTTC TFC); the polytrithiocarbonate composite membrane includes PVDF and a polytrithiocarbonate nanofiltration membrane loaded on the PVDF membrane, and is a composite membrane obtained by combining a polytrithiocarbonate nanofiltration membrane and a PVDF membrane;
[0060] Step 4: Perform post-modification to obtain a post-modified polytrithiocarbonate composite membrane (PTTC-PDMC). The post-modification mechanism is as follows: Figure 2 As shown:
[0061] Step 401, take 7.5×10 -4 mmol of photocatalyst EY, 36.6 mmol of reducing agent TEA, and 11.8 mmol of methacryloyloxyethyltrimethylammonium chloride (DMC) were placed in 7.3 mL of dimethyl sulfoxide to obtain a modification solution. The polytrithiocarbonate composite membrane was immersed in the modification solution and irradiated under 460 nm blue light for 20 h. After removal, washing, and drying for 60 min, the modification was completed, and a post-modified polytrithiocarbonate composite membrane (PTTC-PDMC) was obtained. The post-modified polytrithiocarbonate composite membrane includes PVDF and a post-modified polytrithiocarbonate membrane loaded on the PVDF, and is a composite membrane of post-modified polytrithiocarbonate membrane and PVDF.
[0062] Example 2
[0063] This embodiment is the same as that in Embodiment 1, except that in step 401, 34.3 mmol acrylamide (AM) is used instead of methacryloyloxyethyltrimethylammonium chloride (DMC); the post-modified polytrithiocarbonate composite film obtained in this embodiment is labeled as PTTC-PAM.
[0064] Example 3
[0065] This embodiment is the same as that of Embodiment 1, except that in step 401, 33.9 mmol of acrylic acid (AA) is used instead of methacryloyloxyethyltrimethylammonium chloride (DMC); the post-modified polytrithiocarbonate composite film obtained in this embodiment is labeled as PTTC-PAA.
[0066] Performance Evaluation
[0067] 1. Permeation test of polytrithiocarbonate composite membrane (PTTC TFC) in Example 1
[0068] The separation performance of the PTTC TFC membrane in Example 1 was tested using a cross-flow filtration system. The test method included: placing the PTTC TFC membrane in a membrane tank, using deionized water or an inorganic salt solution with a concentration of 1000 ppm as the feed liquid, measuring the pure water flux or inorganic salt rejection rate, with the feed liquid temperature at room temperature and the feed pressure at 4 bar. The test results are shown in Table 1.
[0069] Table 1. Pure water flux and inorganic salt rejection rate of PTTC TFC membranes
[0070]
[0071] As can be seen, the PTTC TFC membrane of this invention has a pure water flux of up to 143 L·m -2 ·h -1 It exhibits strong selectivity for inorganic salts, with the highest retention rate for Na2SO4 at 96.5% and the lowest retention rate for MgCl2 at only 5.3%.
[0072] 2. Permeation tests of post-modified polytrithiocarbonate composite membranes in Examples 1-3
[0073] The pure water flux of the post-modified polytrithiocarbonate composite membranes of Examples 1-3 was tested according to the above test method. The test method was the same as that for the PTTC TFC membrane in Example 1. The test results are shown in Table 2.
[0074] Table 2 Comparison of pure water flux of different membranes
[0075]
[0076] As can be seen from Tables 1 and 2, the post-modified composite membrane of the present invention significantly improves the pure water flux, with an improvement rate of 15-50%. The improvement rate of pure water flux is equal to (pure water flux of the post-modified composite membrane - pure water flux of the PTTC membrane) / pure water flux of the PTTC membrane. The retention rate of inorganic salts is closely related to the post-modified monomers. PTTC-PDMC and PTTC-PAA both significantly increase the retention rate of inorganic salts and have a general inorganic salt retention effect. PTTC-PAM significantly reduces the retention rate of Na2SO4 compared to PTTC, and the retention rates of each inorganic salt are not significant.
[0077] 3. Structural Confirmation
[0078] The infrared spectrum of the polytrithiocarbonate nanofiltration membrane in Example 1 is as follows: Figure 3 As shown, the infrared spectrum was obtained after removing the PVDF layer from the PTTC TFFC film. It can be seen that at 1734 cm⁻¹, the infrared spectrum... -1 The characteristic peak at 1059 cm⁻¹ belongs to the C=O structural unit of pentaerythritol ester, while the stretching vibration peaks of C=S and CS appear at 1059 cm⁻¹. -1 800 cm -1 Place.
[0079] XPS test results of the polytrithiocarbonate nanofiltration membrane in Example 1 are as follows: Figure 4 As shown, the measurements were taken after removing the PVDF layer from the PTTC TFC membrane. It can be seen that the binding energies of sulfur atoms in C and S are 164.6 eV and 164.2 eV, respectively, and the orbital binding energies of sulfur atoms in C=S are 163.2 eV and 161.9 eV.
[0080] The infrared spectra of the modified polytrithiocarbonate composite films in each embodiment are as follows: Figure 5 As shown, in PTTC-PAM, 1660 cm -1 A C=O stretching vibration peak ν(C=O) belonging to the amide bond appears; in PTTC-PDMC, at 1480 cm⁻¹ -1 A characteristic peak belonging to νC-N appears, at 1551 cm⁻¹ in PTTC-PAA. -1 The location belongs to νCOO - Characteristic peaks.
[0081] Figure 6 This is a schematic diagram of the contact angle test results of the PTTC TFC membrane in Example 1. The results show that the contact angle of the PTTC TFC membrane of the present invention is significantly lower than that of the PVDF substrate membrane, and it has higher wettability.
[0082] Figure 7 Image 'a' is a scanning electron microscope image of the PVDF substrate. Figure 7b is a scanning electron microscope image of PTTC TFC from Example 1. Figure 7 c is an electron micrograph of the cross-sectional morphology of the PVDF substrate. Figure 7 d is an electron micrograph of the cross-sectional morphology of the PTTC TFC film in Example 1, based on... Figure 7 As can be seen, the PVDF substrate has a porous surface. The surface scanning electron microscope image of the PTTC TFC membrane in Example 1 shows no obvious pore structure. Based on the cross-sectional morphology of the PTTC TFC membrane ( Figure 7 As can be seen from d), the polytrithiocarbonate nanofiltration membrane is loaded onto the PVDF membrane, indicating the successful loading of the polytrithiocarbonate membrane onto the PVDF substrate surface.
[0083] Figure 8 The diagram shows the mass change of the post-modified polytrithiocarbonate composite film in Examples 1 to 3 compared to the original mass. In the diagram, weight change% = (mass of post-modified polytrithiocarbonate composite film - mass of PTTCTFC) / (mass of PTTCTFC - mass of PVDF). The results show that, compared to the original mass, the mass of the post-modified polytrithiocarbonate composite film corresponding to each monomer increased significantly, and the surface post-modification was completed.
[0084] Figure 9 Here is a scanning electron microscope image of the post-modified polytrithiocarbonate composite film, in which... Figure 9 a is the post-modified polytrithiocarbonate composite membrane (PTTC-PDMC) of Example 1. Figure 9 b is the post-modified polytrithiocarbonate composite membrane (PTTC-PAM) of Example 2. Figure 9 c represents the post-modified polytrithiocarbonate composite film (PTTC-PAA) of Example 3. It can be seen that the surface morphology of each post-modified polytrithiocarbonate composite film is similar to that of pure PVDF. Figure 7 There are significant differences in a) among them, and none of them have obvious porous structures. The surface morphology of each modified polytrithiocarbonate composite film and the surface morphology of PTTC are different. Figure 7 There are also significant differences in b). Combined with the infrared spectrum, it can be seen that the method of the present invention successfully achieves the post-modification of polytrithiocarbonate composite film.
Claims
1. A method for preparing a polytrithiocarbonate composite membrane, characterized in that, include: Provide trithiocarbonate salt phase solution and α,α''-dibromo-p-xylene organic phase solution; The trithiocarbonate salt phase solution is used to wet the substrate film; An organic phase solution of α,α''-dibromo-p-xylene was placed on a substrate membrane soaked in a trithiocarbonate salt phase solution, and interfacial polymerization was performed to obtain a polytrithiocarbonate composite membrane.
2. The method for preparing the polytrithiocarbonate composite membrane according to claim 1, characterized in that, The method for preparing the trithiocarbonate salt phase solution includes: Using an aqueous solution of carbon disulfide, pentaerythritol tetrakis(3-mercaptopropionic acid), and tetraethylammonium hydroxide as the reactant system, the reactant system was reacted under stirring conditions to obtain a trithiocarbonate salt phase solution.
3. The method for preparing the polytrithiocarbonate composite membrane according to claim 2, characterized in that, In the reactant system, the concentrations of carbon disulfide and pentaerythritol tetrakis(3-mercaptopropionic acid) ester are both 0.2~1.2 mmol / mL; the stirring is magnetic stirring at room temperature for 12~48 h.
4. The method for preparing the polytrithiocarbonate composite membrane according to claim 1, characterized in that, The method for preparing the α,α''-dibromo-p-xylene organic phase solution includes: Under normal temperature and ultrasonic conditions, α,α''-dibromo-p-xylene was dissolved in toluene to obtain an organic phase solution of α,α''-dibromo-p-xylene.
5. The method for preparing the polytrithiocarbonate composite membrane according to claim 4, characterized in that, The concentration of α,α''-dibromo-p-xylene in the organic phase solution is 0.01~4wt%.
6. The method for preparing the polytrithiocarbonate composite membrane according to claim 1, characterized in that, The process of wetting the substrate with a trithiocarbonate salt solution includes: immersing the substrate with the trithiocarbonate salt solution, allowing it to stand for 0-20 minutes, removing the residual trithiocarbonate salt solution on the surface of the membrane, and obtaining a substrate wetted with the trithiocarbonate salt solution.
7. The method for preparing the polytrithiocarbonate composite membrane according to claim 1, characterized in that, An organic phase solution of α,α''-dibromo-p-xylene is placed on a substrate film impregnated with a trithiocarbonate salt phase solution. Interfacial polymerization is then performed to obtain a polytrithiocarbonate composite film, specifically comprising: The organic phase solution of α,α''-dibromo-p-xylene was uniformly poured onto the substrate membrane soaked in the trithiocarbonate salt phase solution. After standing at room temperature for 0-20 min, the membrane was washed and dried to obtain the polytrithiocarbonate composite membrane.
8. A post-modified polytrithiocarbonate composite membrane, characterized in that, Using the polytrithiocarbonate composite membrane prepared by the method of any one of claims 1 to 7 as a chain transfer agent, reversible addition-fragmentation chain transfer polymerization is mediated to achieve polymerization modification of the polytrithiocarbonate composite membrane by functional monomers; the modifying monomers include methacryloyloxyethyltrimethylammonium chloride, acrylic acid, or acrylamide.
9. A method for preparing the post-modified polytrithiocarboxylic acid composite filter membrane as described in claim 8, characterized in that, include: In the presence of a photocatalyst and a reducing agent, the polytrithiocarbonate composite film is immersed in a solution containing the modifying monomer, and polymerized by blue light irradiation to obtain the post-modified polytrithiocarbonate composite film.
10. An application of a polytrithiocarbonate composite membrane prepared by the method described in claim 1 or a post-modified polytrithiocarbonate composite membrane as described in claim 8 in the field of separation.