Preparation method of polyester film based on full-hydroxyl column [5] arene

Abstract

The invention relates to a preparation method of a polyester film based on full-hydroxyl column [5] arene. The polyester film with salt separation is prepared by taking full-hydroxyl column [5] arene as a water-phase monomer through an interfacial polymerization method. The method comprises the following steps: (1) synthesizing methoxy pillar [5] arene from 1, 4-dimethoxybenzene and paraformaldehyde under the catalysis of boron trifluoride diethyl etherate; (2) reacting the purified product with boron tribromide, and removing methyl groups to obtain full-hydroxyl column [5] arene; (3) dissolving the product in an aqueous solution containing triethylamine, and forming a two-phase solution of interfacial polymerization reaction with an n-hexane solution of trimesoyl chloride; and (4) sequentially coating the surface of the polyacrylonitrile ultrafiltration membrane with the aqueous phase solution and the organic phase solution, and carrying out interfacial polymerization reaction to obtain the polyester membrane. Based on the inherent cavity and polyhydroxy characteristics of the full-hydroxyl column [5] arene, compared with a traditional polyamide membrane, the obtained polyester membrane has high permeability and selectivity, can efficiently separate dye and inorganic salt, and is suitable for water treatment processes of printing and dyeing wastewater and the like.

Description

Technical Field

[0001] The present invention relates to the field of preparation of thin-layer composite membrane materials, and in particular to a method for preparing a polyester membrane based on all-hydroxyl column [5] aromatic hydrocarbons, which can be applied to the dyeing salt separation process in the treatment of printing and dyeing wastewater. Background Art

[0002] Polyamide membrane is one of the commonly used polymer membrane materials in the commercial market. It is often used in the fields of seawater desalination, industrial wastewater treatment and resource recovery due to its advantages of high separation efficiency, low comprehensive energy consumption, no phase change, environmental friendliness and simple preparation. The commonly used preparation method is interfacial polymerization, in which polyamine monomers in the aqueous phase undergo amidation reaction with acyl chloride monomers in the organic phase at the interface between the two phases to generate polyamide membranes.

[0003] Polyamide membranes still have certain defects in some industrial water treatments involving organic / inorganic salt separation. For example, in the printing and dyeing industry, dye molecules and inorganic salt ions are valuable resources that coexist in most textile wastewaters. Commonly used piperazine-based polyamide membranes can intercept salts and dyes at the same time, but cannot separate the two, thus failing to achieve the purpose of resource recycling and reuse. In addition, the pure water permeability of piperazine-based polyamide membranes is usually less than 20L·m -2 ·h -1 bar -1 , the filtration efficiency is low. Therefore, it is urgent to construct a new type of membrane material to deal with the problems brought about by the "permeability-selectivity" trade-off.

[0004] A potential solution is to construct a new polyester membrane based on monomers containing hydroxyl or phenol groups. Since the reactivity of hydroxyl groups when reacting with acyl chlorides is lower than that of amine groups, the resulting polyester selective layer is relatively loose, and therefore has higher permeability than general polyamide membranes in most cases.

[0005] In the process of interfacial polymerization, the selection of aqueous phase monomers is particularly important. Different from conventional alcohol-based monomers, the present invention uses a fully hydroxyl columnar [5] aromatic hydrocarbon with an inherent cavity of 0.47 nm as an aqueous phase monomer. 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 the acyl chloride can achieve a high retention 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 recovery treatment and improve the dye / salt separation efficiency of the polyester membrane, the present invention provides a relatively loose polyester selective layer constructed with a macrocyclic molecule with multiple hydroxyl sites and inherent cavities, namely, a fully hydroxyl-column [5] aromatic hydrocarbon, thereby preparing a highly permeable and highly selective polyester membrane, thereby achieving the purpose of dye / salt separation.

[0008] [Technical solution]

[0009] In order to achieve the above object, a method for preparing a polyester film based on perhydroxyl pillar [5] aromatic hydrocarbons is characterized by comprising the following steps:

[0010] (1) Using 1,4-dimethoxybenzene as a synthetic monomer, polyformaldehyde and boron trifluoride etherate as reaction reagents, and dichloroethane as a solvent, methoxy-column[5]arene is prepared by polymerization reaction; after the reaction is completed, methanol is added to obtain a solid product, and after separation and drying, an off-white solid methoxy-column[5]arene is obtained.

[0011] (2) The methoxy-pillar[5]arene obtained in step (1) is treated with boron tribromide as an oxidant and dichloromethane as a solvent to synthesize perhydroxy-pillar[5]arene.

[0012] (3) The fully hydroxylated column [5] aromatic hydrocarbon obtained in step (2) is dissolved in an alkaline aqueous solution of triethylamine as an aqueous phase reaction solution, and trimesoyl chloride is dissolved in n-hexane as an organic phase reaction solution.

[0013] (4) The aqueous solution and the organic solution obtained in step (3) are sequentially coated on the surface of a polyacrylonitrile ultrafiltration membrane, and after the polymerization reaction, heat treatment is performed in an oven to obtain a polyester membrane based on a full hydroxyl column [5] aromatic hydrocarbon group.

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

[0015] In the step (2), the synthesis of the fully hydroxylated column [5] aromatic hydrocarbons comprises the following steps: p-methoxy column [5] aromatic hydrocarbons (1.3 mmol) are weighed and placed in a reaction flask, nitrogen is introduced, 50 mL of dichloromethane is injected, boron tribromide (50 mmol) is slowly added under nitrogen protection, and 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 a grayish white solid fully hydroxylated column [5] aromatic hydrocarbons (1.0 mmol).

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

[0017] In the step (3), the mass fraction (ω) of triethylamine is 4.0%, the mass fraction (ω) of all-hydroxyl column [5] aromatic hydrocarbons is 0.1-1.0%, and the solvent is pure water. The mass fraction (ω) of trimesoyl 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 fully hydroxylated columnar [5] aromatic hydrocarbons is 1.0%, and the mass fraction (ω) of trimesoyl chloride is 0.1%.

[0019] In the step (4), the prepared aqueous solution is poured onto the surface of the polyacrylonitrile ultrafiltration membrane for a soaking time of 3 to 10 minutes, and then the excess solution is poured out, and the residual solution on the membrane surface is squeezed out with a rubber roller. The membrane surface is soaked with the prepared organic solution, and allowed to react for 5 to 10 minutes. After the excess solution is poured out, the membrane is placed in an oven at 60°C for thermal curing for 5 to 10 minutes. After the curing is completed, the polyester membrane is placed in pure water for storage.

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

[0021] [Material source]

[0022] Polyacrylonitrile ultrafiltration membrane, molecular weight cutoff 50000Da, 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, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

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

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

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

[0028] Dichloromethane, analytical grade, 99%, purchased from Tianjin Damao Chemical Reagent;

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

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

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

[0032] n-Hexane, analytical grade, 97%, was purchased from Tianjin Komiou 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 low reactivity with acyl chloride groups, and can form a relatively loose selection layer; unlike conventional alcohol / phenol monomers, a pillar aromatic hydrocarbon-based macrocyclic molecule with an inherent cavity is used, and the cavity inside the molecule can promote the penetration of water molecules; the reaction sites of multiple hydroxyl groups in the molecule react with acyl chloride to form a polyester selection layer, which can achieve efficient interception of organic pollutants; the preparation method of a polyester membrane based on fully hydroxyl pillar [5] aromatic hydrocarbons provided by the present invention adopts an interfacial polymerization method, uses fully hydroxyl pillar [5] aromatic hydrocarbons with an inherent cavity as a water phase monomer, and promotes the dissolution of the monomer and the subsequent esterification reaction by triethylamine, thereby constructing a continuous and complete polyester membrane. By changing the mass fraction of fully hydroxyl pillar [5] aromatic hydrocarbons, the density and separation performance of the membrane can be adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a scanning electron microscope image of the surface and cross section of the polyester film obtained according to Example 1 of the present invention;

[0037] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of the all-hydroxyl column [5] aromatic hydrocarbon obtained in step (2) of Example 1 of the present invention;

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

[0039] Figure 43D images of atomic force microscope obtained according to Examples 1 to 6 of the present invention (corresponding to a, b, c, d, e, and f, respectively). DETAILED DESCRIPTION

[0040] The described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0042] The permeability and separation performance of the polyester membrane based on all-hydroxyl column [5] aromatic hydrocarbons described in the present invention, i.e., flux and retention rate, were measured by a cross-flow filtration device, 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 cm 2 . The polyester film was pre-pressed at a pressure of 0.5MPa for half an hour, and then the pressure was reduced to 0.4MPa, and the volume of liquid flowing out within a certain period of time was recorded. Congo red was used as a typical organic dye, and its aqueous solution concentration was 100mg / L. The dye concentration was determined by measuring the absorbance of the permeate using ultraviolet absorption spectroscopy. Sodium chloride was used as a typical inorganic salt, and its aqueous solution concentration was 1000mg / L. The conductivity of the permeate was measured using a conductivity meter to determine the retention rate.

[0043] In the present invention, flux (J) reflects the permeability of the membrane, J = V / (A·t·P). In the formula, V is the permeate volume (L) on the permeation side, A is the effective area (m 2 ), t is the penetration time (h), and P is the test pressure (bar).

[0044] The retention rate (R) in the present invention reflects the retention performance of the membrane, R = (1-C p / C f )×100%. In the formula, C p With C f are the concentrations of the solute (Congo red or sodium chloride) component in the feed solution and the permeate, respectively.

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

[0046] According to the same steps as Examples 1-6 and Comparative Example 1, a polyester membrane based on fully hydroxy-column [5] aromatic hydrocarbons was prepared, and its pure water flux, rejection rate and dye / salt separation ratio were tested. The test results are shown in Table 1.

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

[0048] Embodiment 1:

[0049] (1) Weigh 1,4-dimethoxybenzene (72 mmol) and paraformaldehyde (362 mmol) into a reaction flask, fill 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, and stir at 25°C for 2 h. After the reaction is completed, add methanol to the reaction flask, collect the generated precipitate by suction filtration, and separate the obtained product using a silica gel column with dichloromethane / petroleum ether = 1:1 as the eluent. After drying the obtained p-methoxy column [5] aromatic hydrocarbon solution, a white powder p-methoxy column [5] aromatic hydrocarbon (10.8 mmol) is obtained.

[0050] (2) p-Methoxy-column [5]arene (1.3 mmol) was weighed and placed in a reaction flask, nitrogen was introduced, 50 mL of dichloromethane was injected, boron tribromide (50 mmol) was slowly added under nitrogen protection, and the mixture was stirred at 25° C. for 36 hours. Subsequently, 50 mL of ice water was added, and the resulting precipitate was collected and washed three times with 0.5 mol of HCl aqueous solution and dichloromethane solvent to obtain off-white solid all-hydroxy-column [5]arene (1.0 mmol).

[0051] (3) Prepare an aqueous phase solution and an oil phase solution, wherein the mass fraction (ω) of triethylamine in the aqueous phase solution is 4.0%, the mass fraction (ω) of all-hydroxyl column [5] 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 the environmental conditions of temperature of 25°C and humidity of 40%, the polyacrylonitrile ultrafiltration membrane was fixed on a polytetrafluoroethylene frame (5×5 cm 2) with the front side facing up. Pour 5mL of the prepared aqueous solution on the surface of the ultrafiltration membrane for 3 minutes, then pour it out, and use a rubber roller to squeeze out the residual solution on the membrane surface. Next, soak it with 5mL of the prepared organic solution for 5 minutes, then pour it out and dry it at room temperature for 30 seconds, then place the membrane in an oven at 60°C for thermal curing for 10 minutes. After curing, store the polyester membrane in pure water at 4°C.

[0053] Embodiment 2:

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

[0055] Embodiment 3:

[0056] A method for preparing a polyester film based on fully hydroxyl-column [5] aromatic hydrocarbons, which is different from that of Example 1 in that the mass fraction (ω) of fully hydroxyl-column [5] aromatic hydrocarbons in step (3) is 0.6%, and the other conditions remain unchanged.

[0057] Embodiment 4:

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

[0059] Embodiment 5:

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

[0061] Embodiment 6:

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

[0063] Comparative Example 1:

[0064] A method for preparing a polyester film based on fully hydroxyl-column [5] aromatic hydrocarbons, which is different from that of Example 1 in that the mass fraction (ω) of fully hydroxyl-column [5] aromatic hydrocarbons in step (3) is 0%, and 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, fully hydroxyl column [5] aromatic hydrocarbons were used as aqueous phase monomers and trimesoyl chloride was used as the organic phase for interfacial polymerization, thereby obtaining a separation layer with a polyester structure as the core. The results in Table 1 show that in Examples 1-6, column [5] aromatic hydrocarbons with multiple hydroxyl reaction sites were introduced into the aqueous phase solution, and the interception rates of Congo red and sodium chloride were improved to varying degrees, among which the interception rate of Congo red reached more than 97%, highlighting the high interception of dye molecules by the obtained polyester membrane. However, due to the low reactivity of hydroxyl and acyl chloride groups, the molecular weight interception of the prepared polyester membrane is relatively large, making it difficult to effectively intercept small molecules such as sodium chloride, thereby achieving efficient separation of dyes and inorganic salts. However, the aqueous phase solution of Comparative Example 1 lacks fully hydroxyl column [5] aromatic hydrocarbons, and a polyester layer cannot be formed, making it difficult to intercept dye molecules, resulting in low dye / salt separation efficiency.

[0068] In Examples 1-6, by increasing the content of all-hydroxyl columnar [5] aromatic hydrocarbons in the aqueous solution, more sub-nanometer molecular cavities were introduced during the interfacial polymerization process, and the free volume fraction of the membrane became larger. The diameter of a water molecule is 0.27 nm, which is much smaller than the intramolecular cavity of all-hydroxyl columnar [5] aromatic hydrocarbons. This provides an additional transmission path for water molecules, which promotes the transmembrane transmission of water molecules. When the concentration is increased to 1.0%, the permeation flux reaches a maximum of 89.4 L·m -2 ·h -1 bar -1 .

[0069] Figure 1 The surface and cross-sectional scanning electron microscope (SEM) images 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 This is the hydrogen nuclear magnetic resonance spectrum of all-hydroxyl column [5] aromatics. The characteristic peaks (such as hydroxyl peak δ = 8.46 ppm, aromatic ring proton peak δ = 6.60 ppm, methoxy peak δ = 3.45 ppm) 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 surfaces of Example groups (af) all present a uniform and continuous polyester selection layer with a small amount of nodular structures. Figure 4 The corresponding atomic force microscope (AFM) three-dimensional images show the surface roughness (R a The values ​​of R 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 transmission of water molecules.

[0071] The present invention adopts interfacial polymerization method, uses full hydroxyl pillar [5] aromatic hydrocarbons with inherent cavities as aqueous phase monomers, and promotes the dissolution of the monomers and subsequent esterification reaction by triethylamine, thereby constructing a continuous and complete polyester membrane. Compared with the polyamide structure, the separation layer of the obtained polyester structure is relatively loose, 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 all-hydroxyl pillar [5] aromatic hydrocarbons, characterized in that: The following steps are involved: (1) Using 1,4-dimethoxybenzene as a synthetic monomer, polyformaldehyde and boron trifluoride etherate as reaction reagents, and dichloroethane as a solvent, methoxy-column[5]arene is prepared by polymerization reaction; after the reaction is completed, methanol is added to obtain a solid product, and after separation and drying, an off-white solid methoxy-column[5]arene is obtained; (2) synthesizing all-hydroxyl-column[5]arene from the methoxy-column[5]arene obtained in step (1) using boron tribromide as an oxidant and dichloromethane as a solvent; (3) dissolving the perhydroxyl column [5] aromatic hydrocarbon obtained in step (2) in an alkaline aqueous solution of triethylamine as an aqueous phase reaction solution, and dissolving trimesoyl chloride in n-hexane as an organic phase reaction solution; (4) The aqueous solution and the organic solution obtained in step (3) are sequentially coated on the surface of a polyacrylonitrile ultrafiltration membrane, and after the polymerization reaction, heat treatment is performed in an oven to obtain a polyester membrane based on a full hydroxyl column [5] aromatic hydrocarbon group.

2. The method for preparing a polyester film based on all-hydroxyl pillar [5] aromatic hydrocarbons according to claim 1, characterized in that: In the step (1), the synthesis of methoxy-column [5] aromatics The method comprises the following steps: weighing 1,4-dimethoxybenzene (72 mmol) and polyformaldehyde (362 mmol) into a reaction bottle, charging with nitrogen, injecting 200 mL of 1,2-dichloroethane, and stirring at 25°C for 1 hour. Slowly adding boron trifluoride ether (76 mmol) under nitrogen protection, stirring at 25°C for 2 hours, adding methanol to the reaction bottle after the reaction is completed, collecting the generated precipitate by suction filtration, using dichloromethane / petroleum ether = 1:1 as an eluent, and separating the obtained product by using a silica gel column, and drying the obtained p-methoxy column [5] aromatic hydrocarbon solution to obtain white powder p-methoxy column [5] aromatic hydrocarbon (10.8 mmol).

3. The method for preparing a polyester film based on all-hydroxyl pillar [5] aromatic hydrocarbons according to claim 1, characterized in that: In the step (2), the specific steps of synthesizing the fully hydroxylated column [5] aromatic hydrocarbons are as follows: p-methoxy column [5] aromatic hydrocarbons (1.3 mmol) are weighed and placed in a reaction flask, nitrogen is introduced, 50 mL of dichloromethane is injected, boron tribromide (50 mmol) is slowly added under nitrogen protection, and 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 a gray-white solid fully hydroxylated column [5] aromatic hydrocarbons (1.0 mmol).

4. The method for preparing a polyester film based on all-hydroxyl pillar [5] aromatic hydrocarbons according to claim 1, characterized in that: In the step (3), the mass fraction (ω) of triethylamine is 4.0%, the mass fraction (ω) of all-hydroxyl column [5] aromatic hydrocarbons is 0.1-1.0%, and the solvent is pure water. The mass fraction (ω) of trimesoyl 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 all-hydroxyl pillar [5] aromatic hydrocarbons according to claim 1, characterized in that: In the step (4), the prepared aqueous solution is poured onto the surface of the polyacrylonitrile ultrafiltration membrane for a soaking time of 3 to 10 minutes, and then the excess solution is poured out, and the residual solution on the membrane surface is squeezed out with a rubber roller. The membrane surface is soaked with the prepared organic solution, allowed to react for 5 to 10 minutes, and the excess solution is poured out. The membrane is placed in an oven at 60°C for thermal curing for 5 to 10 minutes. After curing, the polyester membrane is placed in pure water for storage.

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

6.

7. The method for preparing a polyester film based on all-hydroxyl pillar [5] aromatic hydrocarbons according to claim 1, characterized in that: The prepared polyester film can be applied to the dyeing salt separation process in the treatment of printing and dyeing process wastewater and production wastewater, and can be recycled and utilized by different quality resources.

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