A method for preparing polyester membranes based on all-hydroxyl columnar aromatics [5]

Abstract

This invention relates to a method for preparing a polyester membrane based on perhydroxyl column[5] aromatics. A polyester membrane for dye-salt separation is prepared by interfacial polymerization using perhydroxyl column[5] aromatics as the aqueous monomer. The steps include: (1) synthesizing methoxyl column[5] aromatics from 1,4-dimethoxybenzene and paraformaldehyde under the catalysis of boron trifluoride ether; (2) reacting the purified product with boron tribromide to remove methyl groups and obtain perhydroxyl column[5] aromatics; (3) dissolving the product in an aqueous solution containing triethylamine, and forming a two-phase solution for interfacial polymerization with a hexane solution of trimesoyl chloride; (4) sequentially coating the aqueous solution and organic solution onto the surface of a polyacrylonitrile ultrafiltration membrane, and obtaining the polyester membrane through interfacial polymerization. Based on the inherent cavity and polyhydroxyl characteristics of perhydroxyl column[5] aromatics, compared with traditional polyamide membranes, the obtained polyester membrane has both high permeability and selectivity, and can efficiently separate dyes and inorganic salts, making it suitable for water treatment processes such as dyeing and printing wastewater.

Description

Technical Field

[0001] This invention relates to the field of thin-layer composite membrane material preparation, specifically to a method for preparing a polyester membrane based on all-hydroxyl columnar aromatic hydrocarbons [5], which can be applied to the dye-salt separation process in dyeing and printing wastewater treatment. Background Technology

[0002] Polyamide membranes are among the most commonly used commercially available polymeric membrane materials. Due to their advantages such as high separation efficiency, low overall energy consumption, no phase change, environmental friendliness, and simple preparation, they are frequently used in seawater desalination, industrial wastewater treatment, and resource recovery. The commonly used preparation method is interfacial polymerization, where polyamine monomers in the aqueous phase undergo an amidation reaction with acyl chloride monomers in the organic phase at the interface between the two phases, thereby generating the polyamide membrane.

[0003] Polyamide membranes have certain limitations in some industrial water treatment applications involving the separation of organic matter and inorganic salts. For example, in the dyeing and printing industry, dye molecules and inorganic salt ions are valuable resources coexisting in most textile wastewater. While commonly used piperazine-based polyamide membranes can simultaneously retain salts and dyes, they cannot separate the two, thus failing to achieve resource recycling and reuse. Furthermore, the pure water permeability of piperazine-based polyamide membranes is typically below 20 L·m⁻². -2 ·h -1 ·bar -1 The filtration efficiency is low. Therefore, there is an urgent need to develop a new type of membrane material to address the problems arising from the trade-off between "permeability and selectivity".

[0004] Novel polyester membranes constructed based on monomers containing hydroxyl or phenolic groups offer a potential solution. Because hydroxyl groups are less reactive than amine groups when reacting with acyl chlorides, the resulting polyester selective layer is more porous, thus exhibiting higher permeability in most cases compared to conventional polyamide membranes.

[0005] In the process of interfacial polymerization, the selection of aqueous monomers is particularly important. Unlike conventional alcohol monomers, this invention uses all-hydroxyl columnar aromatic hydrocarbons with an inherent cavity of 0.47 nm[5] as aqueous monomers. The cavity inside the macrocyclic molecule can not only promote the penetration of water molecules, but also has multiple hydroxyl reaction sites. The polyester selective layer generated by the reaction with acyl chloride can achieve a high rejection rate for organic pollutants. Summary of the Invention

[0006] [Technical Issues]

[0007] In order to overcome the limitations of the above-mentioned polyamide membrane in industrial wastewater and resource treatment and improve the dye / salt separation efficiency of polyester membrane, this invention provides a relatively loose polyester selective layer constructed with a macrocyclic molecule with multiple hydroxyl sites and inherent cavities, namely, a fully hydroxyl columnar aromatic hydrocarbon [5], thereby preparing a polyester membrane with high permeability and high selectivity, so as to achieve the purpose of dye / salt separation.

[0008] [Technical Solution]

[0009] To achieve the above objective, a method for preparing a polyester film based on a fully hydroxyl columnar [5] aromatic hydrocarbon is characterized by comprising the following steps:

[0010] (1) Using 1,4-dimethoxybenzene as the synthetic monomer, paraformaldehyde and boron trifluoride ether as the reaction reagents, and dichloroethane as the solvent, methoxy-coated[5]arene was prepared by polymerization reaction; after the reaction was completed, methanol was added to obtain a solid product, which was then separated and dried to obtain a grayish-white solid methoxy-coated[5]arene.

[0011] (2) The methoxy column[5] aromatics obtained in step (1) were used as boron tribromide as an oxidant and dichloromethane as a solvent to synthesize all-hydroxy column[5] aromatics.

[0012] (3) The all-hydroxyl columnar aromatic hydrocarbon obtained in step (2) is dissolved in triethylamine alkaline aqueous solution as an aqueous reaction solution, and pyromellitic methyl chloride is dissolved in n-hexane as an organic reaction solution.

[0013] (4) The aqueous phase solution and organic phase solution obtained in step (3) are sequentially coated on the surface of the polyacrylonitrile ultrafiltration membrane. After polymerization, the membrane is heat-treated in an oven to obtain a polyester membrane based on all-hydroxyl column[5] aromatic hydrocarbon.

[0014] In step (1), the synthesis of methoxy[5] aromatics includes the following steps: 1,4-dimethoxybenzene (72 mmol) and paraformaldehyde (362 mmol) are weighed and placed in a reaction flask, nitrogen is introduced, 200 mL of 1,2-dichloroethane is injected, and the mixture is stirred at 25 °C for 1 h. Boron trifluoride ether (76 mmol) is slowly added under nitrogen protection, and the mixture is stirred at 25 °C for 2 h. After the reaction is completed, methanol is added to the reaction flask, and the precipitate is collected by filtration. The product is separated by silica gel column chromatography using dichloromethane / petroleum ether = 1:1 as the eluent. The obtained p-methoxy[5] aromatic solution is dried to obtain white powder p-methoxy[5] aromatics (10.8 mmol).

[0015] In step (2), the synthesis of the all-hydroxyl column[5] aromatic hydrocarbon includes the following steps: 1.3 mmol of p-methoxyl column[5] aromatic hydrocarbon is weighed and placed in a reaction flask, nitrogen gas is introduced, 50 mL of dichloromethane is injected, and boron tribromide (50 mmol) is slowly added under nitrogen protection. The mixture is stirred at 25 °C for 36 hours. Subsequently, 50 mL of ice water is added, and the resulting precipitate is collected and washed three times with 0.5 mol of HCl aqueous solution and dichloromethane solvent to obtain 1.0 mmol of grayish-white solid all-hydroxyl column[5] aromatic hydrocarbon.

[0016] In step (2), the molar ratio of methoxy[5] aromatic hydrocarbon to boron tribromide is 1.3 mmol: 50 mmol.

[0017] In step (3), the mass fraction (ω) of triethylamine is 4.0%, the mass fraction (ω) of all-hydroxyl columnar aromatic hydrocarbons [5] is 0.1-1.0%, and the solvent is pure water. The mass fraction (ω) of pyromellitic methyl chloride in the organic phase solution is 0.05-0.2%, and the solvent is n-hexane.

[0018] Preferably, the mass fraction (ω) of the all-hydroxyl columnar aromatic hydrocarbon is 1.0%, and the mass fraction (ω) of the trimesoyl chloride is 0.1%.

[0019] In step (4), the prepared aqueous solution is poured onto the surface of the polyacrylonitrile ultrafiltration membrane, and the wetting time is 3-10 minutes. Excess solution is then poured out, and any remaining solution on the membrane surface is removed by squeezing with a rubber roller. The membrane surface is then wetted with the prepared organic solution and allowed to stand for 5-10 minutes. After pouring out excess solution, the membrane is placed in a 60°C oven for heat curing, which takes 5-10 minutes. After curing, the polyester membrane is stored in pure water.

[0020] Preferably, the coating time of the aqueous monomer is 3 min, the wetting time of the organic phase is 5 min, and the heat treatment time is 10 min.

[0021] [Material Source]

[0022] The polyacrylonitrile ultrafiltration membrane, with a molecular weight cutoff of 50,000 Da, was purchased from Zhongke Ruiyang Membrane Technology (Beijing) Co., Ltd.

[0023] 1,4-Dimethoxybenzene, analytical grade, 99%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0024] Paraformaldehyde, analytical grade, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0025] Boron trifluoride diethyl ether, analytical grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0026] 1,2-Dichloroethane, analytical grade, 99.5%, purchased from Tianjin Kemeo Chemical Reagent Co., Ltd.

[0027] Boron tribromide, analytical grade, 99.9%, purchased from Tianjin Kemeo Chemical Reagent Co., Ltd.

[0028] Dichloromethane, analytical grade, 99%, purchased from Tianjin Damao Chemical Reagent Co., Ltd.

[0029] Hydrogen chloride, analytical grade, 37%, purchased from Tianjin Fengchuan Chemical Reagents;

[0030] Triethylamine, analytical grade, 99%, purchased from Shanghai E. En Chemical Technology Co., Ltd.

[0031] Trimethylbenzene chloride, analytical grade, 98%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0032] n-Hexane, analytical grade, 97%, purchased from Tianjin Kemio Chemical Reagent Co., Ltd.

[0033] [Beneficial Effects]

[0034] In summary, the present invention has the following beneficial effects:

[0035] Unlike amine groups, hydroxyl groups have lower reactivity with acyl chloride groups, which can form a relatively loose selective layer. Unlike conventional alcohol / phenol monomers, columnar aromatic macrocyclic molecules with inherent cavities are used, and the cavities inside the molecules can promote the permeation of water molecules. The reaction sites of the polyhydroxyl groups in the molecules can react with acyl chlorides to form a polyester selective layer that can achieve efficient retention of organic pollutants. The present invention provides a method for preparing a polyester membrane based on perhydroxyl columnar [5] aromatics. It adopts an interfacial polymerization method, uses perhydroxyl columnar [5] aromatics with inherent cavities as aqueous monomers, and promotes the dissolution of monomers and subsequent esterification reactions through triethylamine, thereby constructing a continuous and complete polyester membrane. By changing the mass fraction of perhydroxyl columnar [5] aromatics, the density and separation performance of the membrane can be controlled. Attached Figure Description

[0036] Figure 1 These are scanning electron microscope images of the surface and cross-section of the polyester film obtained according to Example 1 of the present invention;

[0037] Figure 2 This is the 1H NMR spectrum of the all-hydroxyl columnar aromatic hydrocarbon obtained in step (2) of Example 1 according to the present invention;

[0038] Figure 3 These are scanning electron microscope images obtained according to embodiments 1 to 6 of the present invention (corresponding to a, b, c, d, e, and f, respectively);

[0039] Figure 4These are three-dimensional atomic force microscope images obtained according to embodiments 1 to 6 of the present invention (corresponding to a, b, c, d, e, and f, respectively). Detailed Implementation

[0040] The described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0041] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0042] The permeation and separation performance of the polyester membrane based on all-hydroxyl column[5] aromatics described in this invention was determined using a cross-flow filtration device, namely flux and rejection rate, and the salt separation ratio was calculated according to the formula. The effective area of ​​the membrane pool in the cross-flow filtration test device is 3.14 cm². 2 The polyester membrane was pre-compressed at 0.5 MPa for half an hour, then the pressure was reduced to 0.4 MPa, and the volume of liquid flowing out over a certain period of time was recorded. Congo red, a typical organic dye, with an aqueous solution concentration of 100 mg / L, was used. The dye concentration was determined by measuring the absorbance of the permeate using ultraviolet absorption spectroscopy. Sodium chloride, a typical inorganic salt, with an aqueous solution concentration of 1000 mg / L, was used. The conductivity of the permeate was measured using a conductivity meter to determine the rejection rate.

[0043] In this invention, flux (J) reflects the membrane's permeation performance, J = V / (A·t·P). Where V is the volume of permeate on the permeate side (L), and A is the effective area of ​​the membrane (m²). 2 ); t is the infiltration time (h); P is the test pressure (bar).

[0044] In this invention, the retention rate (R) reflects the membrane's retention performance, R = (1 - C) / ( ... p / C f )×100%. Where C p With C f These represent the concentrations of the solute (Congo red or sodium chloride) in the feed solution and the permeate, respectively.

[0045] In this invention, the salt separation ratio (α) reflects the separation performance of the membrane, α = (1 - R s ) / (1-R d In the formula, R s With R d The retention rates are for salt and dye, respectively.

[0046] Polyester membranes based on all-hydroxyl column[5] aromatics were prepared according to the same steps as in Examples 1-6 and Comparative Example 1, and their pure water flux, rejection rate and dye / salt separation ratio were tested. The test results are shown in Table 1.

[0047] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to embodiments. However, it should be understood that the following embodiments are only preferred embodiments of the present invention, and the scope of protection claimed by the present invention is not limited thereto.

[0048] Example 1:

[0049] (1) Weigh 1,4-dimethoxybenzene (72 mmol) and paraformaldehyde (362 mmol) into a reaction flask, purge with nitrogen, inject 200 mL of 1,2-dichloroethane, and stir at 25 °C for 1 h. Slowly add boron trifluoride ether (76 mmol) under nitrogen protection, stir at 25 °C for 2 h, and after the reaction is complete, add methanol to the reaction flask, filter and collect the precipitate, use dichloromethane / petroleum ether = 1:1 as the eluent, and separate the product by silica gel column. The obtained p-methoxy[5] aromatic solution was dried to obtain white powder p-methoxy[5] aromatic (10.8 mmol).

[0050] (2) Weigh 1.3 mmol of p-methoxy[5] aromatic hydrocarbon into a reaction flask, purge with nitrogen, inject 50 mL of dichloromethane, and slowly add 50 mmol of boron tribromide under nitrogen protection. Stir at 25 °C for 36 hours. Then add 50 mL of ice water, collect the precipitate and wash it three times with 0.5 mol of HCl aqueous solution and dichloromethane solvent to obtain 1.0 mmol of p-hydroxy[5] aromatic hydrocarbon as a grayish-white solid.

[0051] (3) Prepare aqueous and oil phase solutions. The mass fraction (ω) of triethylamine in the aqueous phase solution is 4.0%, the mass fraction (ω) of all-hydroxyl aromatic hydrocarbons is 1.0%, and the solvent is pure water. The mass fraction (ω) of trimesoyl chloride in the organic phase solution is 0.1%, and the solvent is n-hexane.

[0052] (4) Under environmental conditions of 25℃ and 40% humidity, fix the polyacrylonitrile ultrafiltration membrane on a polytetrafluoroethylene frame (5×5cm). 2Place the membrane with the top side facing up. Pour 5 mL of the prepared aqueous solution onto the ultrafiltration membrane surface and allow it to soak for 3 minutes. Then pour it out, removing any remaining solution from the membrane surface using a rubber roller. Next, soak the membrane with 5 mL of the prepared organic solution for 5 minutes, then pour it out and allow it to dry at room temperature for 30 seconds. Afterward, place the membrane in a 60°C oven for heat curing for 10 minutes. After curing, store the polyester membrane in pure water at 4°C.

[0053] Example 2:

[0054] A method for preparing a polyester film based on hydroxyl columnar [5] aromatic hydrocarbons differs from Example 1 in that the mass fraction (ω) of hydroxyl columnar [5] aromatic hydrocarbons in step (3) is 0.8%, while the other conditions remain unchanged.

[0055] Example 3:

[0056] A method for preparing a polyester film based on hydroxyl columnar [5] aromatics differs from Example 1 in that the mass fraction (ω) of hydroxyl columnar [5] aromatics in step (3) is 0.6%, while the other conditions remain unchanged.

[0057] Example 4:

[0058] A method for preparing a polyester film based on hydroxyl columnar [5] aromatic hydrocarbons differs from Example 1 in that the mass fraction (ω) of hydroxyl columnar [5] aromatic hydrocarbons in step (3) is 0.5%, while the other conditions remain unchanged.

[0059] Example 5:

[0060] A method for preparing a polyester film based on hydroxyl columnar [5] aromatics differs from Example 1 in that the mass fraction (ω) of hydroxyl columnar [5] aromatics in step (3) is 0.25%, while the other conditions remain unchanged.

[0061] Example 6:

[0062] A method for preparing a polyester film based on hydroxyl columnar [5] aromatic hydrocarbons differs from Example 1 in that the mass fraction (ω) of hydroxyl columnar [5] aromatic hydrocarbons in step (3) is 0.1%, while the other conditions remain unchanged.

[0063] Comparative Example 1:

[0064] A method for preparing a polyester film based on hydroxyl columnar [5] aromatics differs from Example 1 in that the mass fraction (ω) of hydroxyl columnar [5] aromatics in step (3) is 0%, while the other conditions remain unchanged.

[0065] Table 1 Performance test results of all-hydroxyl column[5] aromatic polyester film

[0066]

[0067] In the membrane preparation process, perhydroxyl columnar [5] aromatics were used as aqueous monomers and trimesoyl chloride was used as organic phase for interfacial polymerization to obtain a separation layer with polyester structure as the core. Table 1 shows that in Examples 1-6, columnar [5] aromatics with multiple hydroxyl reaction sites were introduced into the aqueous solution, and the rejection rates of Congo red and sodium chloride were improved to varying degrees. Among them, the rejection rate of Congo red reached more than 97%, highlighting the high rejection rate of dye molecules by the obtained polyester membrane. However, due to the low reactivity of hydroxyl groups and acyl chloride groups, the prepared polyester membrane has a large molecular weight rejection, making it difficult to effectively reject small molecules such as sodium chloride, thus achieving efficient separation of dyes and inorganic salts. In contrast, the aqueous solution of Comparative Example 1 lacked perhydroxyl columnar [5] aromatics, so a polyester layer could not be formed, making it difficult to retain dye molecules, resulting in low dye / salt separation efficiency.

[0068] In Examples 1-6, by increasing the content of perhydroxyl columnar [5] aromatics in the aqueous solution, more sub-nanometer molecular cavities were introduced during interfacial polymerization, resulting in a larger free volume fraction of the membrane. Since the diameter of water molecules is 0.27 nm, much smaller than the intramolecular cavity of perhydroxyl columnar [5] aromatics, water molecules have additional transport paths, promoting transmembrane transport. The permeation flux reached its maximum of 89.4 L·m when the concentration was increased to 1.0%. -2 ·h -1 ·bar -1 .

[0069] Figure 1 Scanning electron microscope (SEM) images of the surface and cross-section of the polyester film prepared in Example 1 are shown. The surface morphology is continuous and uniform, and there is no obvious pore structure. The cross-sectional image shows that the thickness of the polyester layer is 56 nm. The thinner selective layer is conducive to the penetration of water molecules. Figure 2 The nuclear magnetic resonance hydrogen spectrum of the all-hydroxyl column[5] aromatic hydrocarbon shows that the characteristic peaks (such as hydroxyl peak δ=8.46ppm, aromatic ring proton peak δ=6.60ppm, methoxy peak δ=3.45ppm) match the target molecular structure, and the peak area ratio is 1:1:1, which verifies the purity of the product and provides molecular structure support for the separation performance of the polyester membrane.

[0070] Figure 3 SEM images of Examples 1-6 (a, b, c, d, e, f) are shown. The surface of Example group (af) shows a uniform and continuous polyester selective layer with a small number of nodular structures. Figure 4 For the corresponding atomic force microscope (AFM) three-dimensional images, the surface roughness (R) of Example Group (af) a The values ​​(R0.05) are all below 26 nm, indicating a smooth film surface. At higher concentrations, R0.05 aThe value is also relatively high, which is beneficial to increase the contact area between the membrane surface and the feed liquid, and promote the transport of water molecules.

[0071] This invention employs interfacial polymerization, utilizing the inherently hollow all-hydroxyl columnar aromatic hydrocarbons [5] as aqueous monomers, and using triethylamine to promote the dissolution of the monomers and subsequent esterification reactions, thereby constructing a continuous and complete polyester membrane. Compared to the polyamide structure, the resulting polyester structure separation layer is more porous, which can improve the practical efficiency of the composite membrane in dye / salt separation.

Claims

1. A method for preparing a polyester film based on a fully hydroxyl columnar [5] aromatic hydrocarbon, characterized in that, Includes the following steps: (1) Using 1,4-dimethoxybenzene as the synthetic monomer, paraformaldehyde and boron trifluoride ether as the reaction reagents, and dichloroethane as the solvent, methoxy-coated[5]arene was prepared by polymerization reaction; after the reaction was completed, methanol was added to obtain a solid product, which was then separated and dried to obtain a grayish-white solid methoxy-coated[5]arene. (2) The methoxy column[5] aromatics obtained in step (1) were used as boron tribromide as an oxidant and dichloromethane as a solvent to synthesize all-hydroxy column[5] aromatics; (3) Dissolve the all-hydroxyl columnar aromatic hydrocarbon obtained in step (2) in an alkaline aqueous solution of triethylamine as an aqueous phase reaction solution, and dissolve pyromellitic methyl chloride in n-hexane as an organic phase reaction solution; (4) The aqueous phase solution and organic phase solution obtained in step (3) are sequentially coated on the surface of the polyacrylonitrile ultrafiltration membrane. After polymerization, the membrane is heat-treated in an oven to obtain a polyester membrane based on all-hydroxyl column[5] aromatic hydrocarbon.

2. The method for preparing a polyester film based on a fully hydroxyl columnar [5] aromatic hydrocarbon according to claim 1, characterized in that, In step (1), the synthesis of methoxy-column [5] aromatic hydrocarbons The steps include: weighing 1,4-dimethoxybenzene (72 mmol) and paraformaldehyde (362 mmol) into a reaction flask, filling it with nitrogen, injecting 200 mL of 1,2-dichloroethane, stirring at 25°C for 1 h, slowly adding boron trifluoride ether (76 mmol) under nitrogen protection, stirring at 25°C for 2 h, adding methanol to the reaction flask after the reaction is complete, collecting the precipitate by filtration, using dichloromethane / petroleum ether = 1:1 as the eluent, separating the obtained product by silica gel column chromatography, and drying the obtained p-methoxy[5] aromatic solution to obtain white powder p-methoxy[5] aromatic (10.8 mmol).

3. The method for preparing a polyester film based on a fully hydroxyl columnar [5] aromatic hydrocarbon according to claim 1, characterized in that, In step (2), the specific steps for the synthesis of the all-hydroxyl column[5] aromatic hydrocarbon are as follows: weigh p-methoxy column[5] aromatic hydrocarbon (1.3 mmol) into a reaction flask, fill it with nitrogen, inject 50 mL of dichloromethane, slowly add boron tribromide (50 mmol) under nitrogen protection, stir at 25 °C for 36 hours, then add 50 mL of ice water, collect the precipitate and wash it three times with 0.5 mol HCl aqueous solution and dichloromethane solvent to obtain a grayish-white solid of all-hydroxyl column[5] aromatic hydrocarbon (1.0 mmol).

4. The method for preparing a polyester film based on a fully hydroxyl columnar [5] aromatic hydrocarbon according to claim 1, characterized in that, In step (3), the mass fraction (ω) of triethylamine is 4.0%, the mass fraction (ω) of all-hydroxyl columnar aromatic hydrocarbon [5] is 0.1-1.0%, the solvent is pure water, the mass fraction (ω) of pyromellitic trimethylol chloride in the organic phase solution is 0.05-0.2%, and the solvent is n-hexane.

5. The method for preparing a polyester film based on a fully hydroxyl columnar [5] aromatic hydrocarbon according to claim 1, characterized in that, In step (4), the prepared aqueous solution is poured onto the surface of the polyacrylonitrile ultrafiltration membrane for 3-10 minutes. Then, the excess solution is poured out, and the residual solution on the membrane surface is removed by squeezing with a rubber roller. The membrane surface is then wetted with the prepared organic solution and allowed to stand for 5-10 minutes. The excess solution is then poured out, and the membrane is placed in an oven at 60°C for heat curing for 5-10 minutes. After curing, the polyester membrane is stored in pure water.

6. The method for preparing a polyester film based on a fully hydroxyl columnar [5] aromatic hydrocarbon according to claim 1, characterized in that, The prepared polyester membrane exhibited a pure water flux of 12.7–89.4 Lm at a test pressure of 0.4 MPa. - 2·h -1 ·bar -1 The rejection rate for Congo red was >97%, the rejection rate for NaCl was 4.3–32.5%, and the dye / salt separation ratio was 27.0–45.

6.

7. The method for preparing a polyester film based on a fully hydroxyl columnar [5] aromatic hydrocarbon according to claim 1, characterized in that, The prepared polyester membrane can be applied to the salt separation process in the treatment of dyeing and printing wastewater and production wastewater, and can be recycled and reused in a differentiated manner.

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