Composite membrane based on diethanolamine functionalized pillararenes and preparation method and application thereof

Abstract

The present application relates to the technical field of separation membrane, and particularly relates to a composite membrane based on diethanolamine functionalized pillararene and a preparation method and application thereof. Diethanolamine functionalized pillararene is designed and synthesized as a key water phase monomer for the first time. The innovative molecule simultaneously introduces a tertiary amine and a highly reactive strong hydrophilic hydroxyl group. The bifunctional design enables the pillararene and the acyl chloride monomer to form a polyester membrane on the surface of the base membrane through an interfacial polymerization reaction, thereby realizing the synergistic and precise regulation of the hydrophilicity, crosslinking density and selectivity of the membrane separation layer, and breaking through the performance bottleneck of relying only on the monofunctionality of the hydroxyl group. The composite membrane provided by the present application not only focuses on the flux and retention rate, but also takes the anti-pollution performance, high flux recovery rate and long-term running stability in actual wastewater as core evaluation indexes and optimization targets, and is directly aimed at and solves the application problems in the actual water treatment, different dye molecules and antibiotic separation processes.

Description

Diethanolamine-functionalized columnar aromatic composite membranes, their preparation methods and applications Technical Field

[0001] This invention relates to the field of separation membrane technology, and in particular to composite membranes based on diethanolamine-functionalized columnar aromatics, their preparation methods, and applications. Background Technology

[0002] Membrane separation technology, as a key technology for achieving efficient and energy-saving separation of substances, plays an irreplaceable role in wastewater treatment, resource recovery, and other fields. Among them, polyester membranes have attracted widespread attention due to their excellent chemical stability, mechanical strength, and solvent resistance. However, traditional polyester membranes generally suffer from the problem of difficulty in simultaneously achieving high water flux and high retention rate, and are susceptible to fouling by organic matter in the water, leading to irreversible flux decline, which severely restricts the improvement of their application efficiency.

[0003] To overcome the aforementioned technical limitations, introducing macrocyclic supramolecular molecules with specific functions into the membrane matrix to regulate membrane structure and interfacial properties has become an important direction for technological development. However, existing technical solutions suffer from limitations such as singular functionalization strategies and limited performance regulation space. Most current research focuses on introducing a single hydrophilic group. While such monofunctionalization strategies can improve hydrophilicity, they have weak capabilities for fine-tuning the membrane crosslinking network structure, making it difficult to actively and precisely design the selective retention of specific pollutants while simultaneously increasing flux. This severely restricts further optimization of membrane performance and its practical application.

[0004] Meanwhile, most existing studies are limited to testing membrane performance in simulated single pollutant systems (such as Congo red / NaCl solution), lacking a systematic evaluation of the membrane's long-term operational stability and anti-fouling durability in actual industrial wastewater with complex composition and high pollution load, resulting in unclear prospects for the industrial application of the material.

[0005] Therefore, how to break through the single-functionalization strategy and provide a new type of composite membrane is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the related art. To this end, the first objective of the present invention is to provide a method for preparing a composite membrane based on diethanolamine-functionalized columnar aromatics; the second objective of the present invention is to provide a composite membrane based on diethanolamine-functionalized columnar aromatics; and the third objective of the present invention is to provide applications of the composite membrane based on diethanolamine-functionalized columnar aromatics.

[0007] To achieve the first objective, the technical solution adopted by this invention is as follows:

[0008] The preparation method of composite membrane based on diethanolamine functionalized columnar aromatics includes the following steps:

[0009] S100. Prepare an aqueous solution containing the columnar aromatic hydrocarbon and an organic solution containing the acyl chloride monomer, respectively.

[0010] The concentration of the columnar aromatic hydrocarbon is 0.05% (w / v) to 0.10% (w / v), and the concentration of the acyl chloride monomer is 0.08% (w / v) to 0.12% (w / v).

[0011] S200: A composite membrane based on diethanolamine-functionalized columnar aromatics is prepared by interfacial polymerization reaction between the aqueous solution and the organic solution on the surface of the base membrane.

[0012] The structural formula of the columnar aromatic hydrocarbon is shown below:

[0013] n is 4, 5 or 6.

[0014] The columnar aromatic hydrocarbon is a linear polymer covalently linked to phenolic oxygen atoms and flexible alkyl chains. This structure organically combines the molecular recognition ability of the columnar aromatic hydrocarbon with the mechanical properties of the polymer. The hydroxyl groups in the -N(CH2CH2OH)2 side chain can react efficiently with acyl chlorides (-COCl) to form a polyester separation layer containing tertiary amine side groups on the base membrane surface, achieving synergistic regulation of the membrane structure. Although the tertiary amine groups in the molecule do not participate in crosslinking, their introduction can enhance the positive charge or hydrophilicity of the membrane surface, synergistically working with the ester crosslinking network to improve separation selectivity. Simultaneously, the tertiary amine can synergistically work with the cavity structure, significantly improving the recognition selectivity and binding ability of specific guest molecules through electrostatic interactions. Therefore, the bifunctional design of the side chain structure enables synergistic and precise regulation of the hydrophilicity, crosslinking density, and selectivity of the membrane separation layer, overcoming the performance bottleneck of relying solely on the single function of hydroxyl groups.

[0015] The steric hindrance and electronic effects of the methoxy group (-OCH3) alter the electron cloud density and cavity size of pillar aromatics, thereby affecting their recognition ability and selectivity for guest molecules. Simultaneously, the presence of the methoxy group can increase the thermal decomposition temperature of the polymer and enhance the stability of the interfacial polymer at high temperatures.

[0016] Furthermore, the structural formula of the columnar aromatic hydrocarbon is shown below:

[0017] ;

[0018] The synthesis process includes the following steps:

[0019] S110. Intermediate I was synthesized by reacting 1,4-dibromobutane with hydroquinone, and its structural formula is shown below:

[0020] ;

[0021] S120. Intermediate II is synthesized by reacting intermediate I with 1,4-dimethoxybenzene, with the structural formula shown below:

[0022] ;

[0023] S130. The columnar aromatic hydrocarbon is synthesized by reacting intermediate II with diethanolamine.

[0024] Furthermore, in step S100, the aqueous solution also contains a reaction promoter, which is selected from organic bases.

[0025] Furthermore, the organic base is selected from triethylamine, and the concentration of triethylamine is 0.8% (w / v) to 1.2% (w / v).

[0026] Further, in step S100, the solvent of the aqueous solution is selected from a mixed solvent of water and N,N-dimethylacetamide, with a volume ratio of 1:1.

[0027] Further, in step S100, the acyl chloride monomer is selected from trimesoyl chloride, and the solvent of the organic phase solution is selected from n-hexane.

[0028] Further, in step S200, the base film is selected from polyacrylonitrile film.

[0029] To achieve the second objective, the technical solution adopted by this invention is as follows:

[0030] The composite membrane based on diethanolamine-functionalized columnar aromatics is prepared using any of the above-described methods for preparing the composite membrane based on diethanolamine-functionalized columnar aromatics.

[0031] To achieve the third objective, the technical solution adopted by this invention is as follows:

[0032] The application of the diethanolamine-functionalized columnar aromatic hydrocarbon composite membrane involves using the composite membrane as a separation membrane, wherein the separation membrane is used for any one or more of the following:

[0033] I. Isolation of different antibiotics;

[0034] II. Wastewater treatment containing antibiotics;

[0035] III. Separation of different dyes;

[0036] IV. Wastewater treatment containing dye molecules;

[0037] V. Wastewater treatment containing different antibiotics and dye molecules.

[0038] Furthermore, the antibiotic is selected from any one or at least two of the following:

[0039] Bacitracin, cefoperazone, and clindamycin phosphate;

[0040] The dye is selected from any one or at least two of the following:

[0041] Crystal Violet, Methyl Orange, Methylene Blue, Methyl Green, Congo Red, Coomassie Brilliant Blue, and Alsin Blue.

[0042] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0043] This invention provides a method for preparing composite membranes based on diethanolamine-functionalized columnar aromatic hydrocarbons. For the first time, diethanolamine-functionalized columnar aromatic hydrocarbons were designed and synthesized as key aqueous monomers. This innovative molecule simultaneously introduces a tertiary amine and highly reactive, strongly hydrophilic hydroxyl groups. This bifunctional design enables the columnar aromatic hydrocarbons and acyl chloride monomers to form a polyester membrane on the surface of the base membrane through interfacial polymerization, thereby achieving synergistic and precise control over the hydrophilicity, crosslinking density, and selectivity of the membrane separation layer, overcoming the performance bottleneck of relying solely on the single function of hydroxyl groups.

[0044] The composite membrane provided by this invention not only focuses on flux and rejection rate, but also takes antifouling performance, high flux recovery rate and long-term operational stability in actual wastewater as core evaluation indicators and optimization goals. This reflects the transformation of R&D concept from material performance to product efficiency, and aims to directly address and solve application problems in actual water treatment, separation of different dye molecules and antibiotics.

[0045] The composite membrane based on diethanolamine-functionalized columnar aromatics provided by this invention has the following advantages:

[0046] First, it simultaneously possesses high flux and high selectivity, thus resolving the core contradiction of traditional membranes where increased flux leads to decreased rejection rate.

[0047] Second, it has excellent flux stability. After 10 hours of anti-fouling test, the flux retention rate is high and the recovery is good, with no obvious attenuation.

[0048] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0049] Figure 1 shows the columnar aromatic hydrocarbon provided in Example 1 of the present invention. 1 H NMR spectrum.

[0050] Figure 2 is the Fourier transform infrared (FTIR) spectrum of the composite membrane based on diethanolamine-functionalized columnar aromatic hydrocarbons provided in Example 2 of the present invention.

[0051] Figure 3 is a scanning electron microscope (SEM) image of the composite membrane based on diethanolamine-functionalized columnar aromatics provided in Example 2 of the present invention.

[0052] Figure 4 is a high-resolution X-ray photoelectron spectroscopy (XPS) C1s spectrum of the composite membrane based on diethanolamine-functionalized columnar aromatics provided in Example 2 of the present invention.

[0053] Figure 5 shows the flux variation of the composite membrane based on diethanolamine-functionalized columnar aromatics under different concentrations of DAP5 provided in Example 3 of the present invention.

[0054] Figure 6 shows the effect of different reaction times provided in Example 3 of the present invention on the performance of the composite membrane based on diethanolamine-functionalized columnar aromatics.

[0055] Figure 7 is a scatter plot showing the relationship between dye rejection rate and molecular weight provided in Example 4 of the present invention.

[0056] Figure 8 shows the UV-Vis absorption spectra of the two different dye molecule mixtures provided in Example 5 of the present invention before and after filtration.

[0057] Figure 9 is a bar chart showing the retention of three different antibiotics by the composite membrane based on diethanolamine-functionalized columnar aromatics provided in Example 6 of the present invention.

[0058] Figure 10 is a normalized flux-time curve provided in Embodiment 7 of the present invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention, but cannot be used to limit the scope of this invention.

[0060] In the following embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available, unless otherwise specified, and are carried out in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0061] Example 1

[0062] Preparation of columnar aromatics The synthesis route is shown below:

[0063] ;

[0064] The process is as follows:

[0065] I. Synthetic Intermediate I.

[0066] 1,4-Dibromobutane (13 mL, 0.1 mol) was added to an acetonitrile solution (200 mL) containing hydroquinone (5 g, 0.045 mol) and potassium carbonate (31 g, 0.227 mol). The mixture was then heated under reflux for 48 h in a nitrogen atmosphere. The solid was removed by filtration, and the solvent was removed from the filtrate by vacuum distillation to obtain the crude product. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / dichloroethane, volume ratio 1:1) to obtain intermediate I.

[0067] II. Synthetic intermediate II.

[0068] Under a nitrogen atmosphere, intermediate I (1.9 g, 5 mmol) and 1,4-dimethoxybenzene (5.5 g, 40 mmol) were dissolved in 1,2-dichloroethane (80 mL). Then, paraformaldehyde (7.5 g, 250 mmol) and boron trifluoride diethyl ether complex (6.4 mL, 50 mmol) were added sequentially. After stirring at room temperature for 30 min, the reaction solution was poured into methanol, and the precipitate was collected by filtration. The collected precipitate was added to dichloromethane (150 mL), and the insoluble matter was removed by filtration. The organic layer was collected and washed twice with water (100 mL). The solution was dried with anhydrous Na2SO4 and evaporated to obtain the crude product. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / dichloromethane, volume ratio 1:1) to obtain intermediate II.

[0069] III. Synthesis of the target compound.

[0070] Under a nitrogen atmosphere, triethylamine (5 mL) was added to 100 mL of acetonitrile solution containing intermediate II (8.62 g, 8.68 mmol) and diethanolamine (7.25 g, 69.0 mmol). The mixture was heated to 80 °C and stirred for 24 h. The reaction system was then cooled to room temperature, and the solvent was removed by rotary evaporation under reduced pressure. Dichloromethane (150 mL) was added, and the mixture was filtered to remove insoluble matter. The organic layer was collected and washed twice with water (100 mL). The residue was dried over anhydrous Na₂SO₄ and evaporated to obtain the crude product. This crude product was subjected to silica gel column chromatography (eluent: dichloromethane / methanol, volume ratio 10:1) to obtain the pale yellow target compound, denoted as DAP5. 1 The H NMR spectrum is shown in Figure 1.

[0071] Example 2

[0072] Prepare composite membranes based on diethanolamine-functionalized columnar aromatics.

[0073] 1. Preparation of aqueous solution: Add DAP5 and triethylamine (as a reaction promoter) to a mixed solvent of N,N-dimethylacetamide / deionized water (1:1, v:v), and sonicate for 5 minutes to completely dissolve it.

[0074] The concentration of DAP5 in the aqueous solution is 0.05% (w / v) to 0.10% (w / v), preferably 0.075% (w / v), and this example uses the preferred concentration;

[0075] The concentration of triethylamine in the aqueous solution is 0.8% (w / v) to 1.2% (w / v), preferably 1% (w / v), and this example uses the preferred concentration.

[0076] II. Preparation of organic phase solution: Dissolve trimesoyl chloride (TMC) in n-hexane to obtain the solution;

[0077] In the organic phase solution, the concentration of TMC is 0.08% (w / v) to 0.12% (w / v), preferably 0.1% (w / v), and the preferred concentration is selected in this embodiment.

[0078] III. Using polyacrylonitrile (PAN) membrane as the supporting substrate, a composite membrane is prepared by interfacial polymerization reaction, as follows:

[0079] Soak the polyacrylonitrile (PAN) membrane in deionized water for 24 hours. After soaking, gently wipe it clean with absorbent paper. Then, cut the PAN to 5cm x 5cm size and lay it flat on a clean glass plate. Cover it with a perforated rubber gasket, and then stack a polytetrafluoroethylene mold (2cm in diameter) on top. Use clamps to secure the membrane in the mold and keep it horizontal. Then, add 3mL of aqueous solution along the edge of the mold using a plastic pipette and soak the PAN base membrane for 5 minutes. After soaking, pour the aqueous solution into a waste bottle. Next, disassemble the molds one by one, remove the residual solvent on the surface of the PAN base membrane using a rubber roller, and then reassemble the molds in the initial order.

[0080] After ensuring the mold is placed horizontally, add 3 mL of organic phase solution along the edge of the mold to allow the TMC in the organic phase solution to undergo interfacial polymerization with the columnar aromatic hydrocarbons in the aqueous phase solution on the surface of the polyacrylonitrile membrane. After the reaction time reaches the required value (the membrane formation time is controlled between 1 and 8 minutes), pour the organic phase solution into a waste bottle. Then, add 2 mL of n-hexane along the edge to stop the reaction. After adding the n-hexane, let it stand for 1 minute. Then, pour out the solution and place the mold in a forced-air drying oven for thermal crosslinking treatment. The thermal crosslinking time is 7 minutes. After the thermal crosslinking is completed, remove the mold sequentially to obtain the composite membrane based on diethanolamine-functionalized columnar aromatic hydrocarbons (denoted as DAP5-M). Its FTIR spectrum is shown in Figure 2. From this figure, it can be seen that DAP5-M has a high FTIR spectrum at 1724 cm⁻¹. -1 There is a clear absorption peak at [value], which is the characteristic absorption peak of ester carbonyl (-COO-), indicating that the ester functional group has been successfully introduced into DAP5-M.

[0081] The SEM image of DAP5-M is shown in Figure 3. From the image, it can be seen that the surface of the composite film exhibits an uneven honeycomb-like or wrinkled structure. These structures are composed of a large number of interconnected units. The size of these units is approximately between 100 and 300 nm. They form an obvious network with each other. The overall structure is relatively dense, but there are also certain pores.

[0082] The XPS spectrum of DAP5-M is shown in Figure 4. From this figure, we can see that the surface carbon chemical states of DAP5-M mainly include: carbon skeleton (C–C / C–H), oxygen-containing single bonds (C–O), and ester / carbonyl groups (O=C–O / C=O).

[0083] Example 3

[0084] The specific process for conducting water flux testing in a crossflow device is as follows:

[0085] The prepared composite membrane was installed in a cross-flow filtration system (effective membrane area 3.14 cm²). 2 The test solution used was a circular membrane with a diameter of approximately 2 cm (Crystal Violet, CV, molecular weight 407.98 Da) at a concentration of 50 ppm. The pump was turned on to raise the system pressure to the target value (4 bar) and maintained for 5 minutes to check for leaks in the piping and connections. After confirming no leaks, the permeate outlet was opened to prepare for the test. The test liquid was injected into the feed end, and the valve was adjusted to stabilize the system pressure at the target pressure (4 bar). This pressure was maintained for 30 minutes to allow the permeate pressure and flow rate to stabilize. The collected permeate volume, collection time, and operating pressure were recorded. The water flux was calculated using the following formula:

[0086] P=ΔV / (A×t×p)

[0087] P is the permeation flux, with units of (L·m). -2 ·h -1 ·bar -1 );

[0088] ΔV is the volume of permeate collected, in L;

[0089] A represents the effective membrane area, in m². 2 ;

[0090] t represents the permeate collection time, in hours (h).

[0091] p represents the transmembrane pressure, measured in bar.

[0092] The test results are shown in Figures 5 and 6.

[0093] Figure 5 shows that the flux reaches its peak (approximately 52 L·m⁻¹) when the DAP₅ concentration is 0.075% (w / v). -2 ·h -1 ·bar -1 );

[0094] As shown in Figure 6, when the reaction time of the interfacial polymerization reaction is ≥3 min, the rejection rate is close to 100% and can remain stable. When the reaction time is 3 min, although the flux decreases, the rejection rate is close to 100%. Therefore, this reaction time is a better condition that balances flux and selectivity.

[0095] Therefore, this embodiment shows that, by adjusting the time and concentration, the composite membrane based on diethanolamine-functionalized columnar aromatics exhibits optimal performance when the DAP5 concentration is 0.075% (w / v), the film formation time is 3 min, and the flux reaches 53.19 L·m⁻¹. -2 ·h -1 ·bar -1 The retention rate of crystal violet reached over 99%.

[0096] Example 4

[0097] The composite membrane based on diethanolamine-functionalized columnar aromatics, which exhibits the best performance, was selected, and its retention capacity for different dye molecules was tested. The results are shown in Figure 7. From the figure, it can be seen that the composite membrane has almost complete retention capacity for dye molecules with a molecular weight greater than 400 Da, indicating that it has good selectivity. For MO and MB dye molecules with similar molecular weights, the retention capacity is significantly different. This indicates that for small molecule dyes, the separation effect depends not only on the molecular weight, but may also be closely related to factors such as the chemical structure and charge properties of the dye.

[0098] In the figure, CV represents crystal violet with a molecular weight of 407.9 Da;

[0099] MO stands for methyl orange, with a molecular weight of 327.34 Da.

[0100] MB is methylene blue, with a molecular weight of 319.85 Da;

[0101] MG is methyl green with a molecular weight of 458.5 Da.

[0102] CR is Congo Red, with a molecular weight of 696.65 Da;

[0103] CBB is Coomassie Brilliant Blue with a molecular weight of 825.97 Da;

[0104] AB is Alsinlan 8GX, with a molecular weight of 1298.88 Da.

[0105] Example 5

[0106] A composite membrane based on diethanolamine-functionalized columnar aromatics with optimal performance was selected to test its separation effect on AB and MO. The feed solution was a mixture of AB / MO binary dyes (the concentration of AB and MO was 50 ppm). The system pressure was 4 bar and the running time was 30 min. Samples of feed solution and permeate (≥10 mL each) were collected, and the absorbance at the characteristic wavelengths of the dyes was measured using a UV-Vis spectrophotometer. The results are shown in Figure 8. From the figure, it can be seen that after membrane separation, the UV-Vis absorption spectrum of the permeate still has an absorption signal in the characteristic absorption wavelength range of AB (about 460 nm), while the characteristic absorption peak of MO in the range of 620 nm to 650 nm is still obvious. This spectral change proves that the composite membrane provided by this invention achieves almost complete retention of the macromolecular dye AB, while allowing the small molecule dye MO to pass through. This indicates that it has a high selective separation ability for the AB and MO mixed dyes.

[0107] Example 6

[0108] The composite membrane based on diethanolamine-functionalized columnar aromatics with the best performance was selected, and its retention effect on bacitracin, cefoperazone, and clindamycin phosphate was tested. The feed solution was a mixture containing bacitracin, cefoperazone, and clindamycin phosphate (all three concentrations were 50 ppm), and the system pressure was 4 bar. The test results are shown in Figure 9. It can be seen from the figure that the composite membrane has a retention effect of nearly 100% on these three different antibiotics.

[0109] Example 7

[0110] The composite membrane based on diethanolamine-functionalized columnar aromatics with the best performance was selected, and its antifouling ability was tested using a cross-flow filtration system.

[0111] During the testing process, the system pressure was 4 bar, and the testing time was 10 hours. The membrane's antifouling ability was tested using two pollutants: humic acid (HA) and bovine serum albumin (BSA) at a concentration of 100 ppm. The BSA and HA antifouling tests aimed to systematically evaluate the membrane's resistance to two typical pollutants (protein macromolecules and natural organic acids), verifying the broad-spectrum nature and mechanism of its antifouling performance. By monitoring flux decay and recovery rates, the membrane's anti-adsorption, anti-clogging, and easy-to-clean characteristics can be revealed, thereby predicting its long-term operational stability and practical value in treating complex real-world water bodies, providing key performance data for the practical application of membrane materials.

[0112] The testing steps are as follows:

[0113] Step 1, Measure the initial flux (J0): Use deionized water as the feed liquid, run at the set pressure (4 bar), and record the steady-state flux J0;

[0114] Step 2: Measure the flux during the pollution phase (J) t ): Switch deionized water to BSA or HA aqueous solution, and filter continuously at the same pressure for 2 hours, recording the real-time flux J every 30 minutes. t

[0115] Step 3: Calculate the flux retention rate. The formula for calculating the flux retention rate is shown below:

[0116] Flux retention rate = J t / J0×100%;

[0117] Step 4, Cleaning and Recovery Test: After the fouling is resolved, rinse the membrane surface with deionized water and measure the deionized water flux J1 again. The formula for calculating the flux recovery rate is as follows:

[0118] Flux recovery rate: J1 / J0 × 100%;

[0119] Flux retention rate (J) t The flux recovery rate (J1 / J0) and flux recovery rate (J1 / J0) are visualized as shown in Figure 10. From the figure, we can see that the flux recovery rate is very high after two cleaning cycles, indicating that the membrane has good antifouling reversibility, which means that the composite membrane is recoverable. The flux recovery rate of the second cycle is slightly lower than that of the first cycle, indicating that there is a small amount of irreversible fouling, but the overall performance is still stable, which means that the composite membrane has long-term stability.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite membrane based on diethanolamine-functionalized columnar aromatics, characterized in that, The process includes the following steps: S100, preparing an aqueous solution containing the columnar aromatic hydrocarbon and an organic solution containing an acyl chloride monomer, respectively; wherein the concentration of the columnar aromatic hydrocarbon is 0.05% (w / v) to 0.10% (w / v), and the concentration of the acyl chloride monomer is 0.08% (w / v) to 0.12% (w / v); S200, using the aqueous solution and the organic solution to undergo an interfacial polymerization reaction on the surface of a base membrane to prepare a composite membrane based on diethanolamine-functionalized columnar aromatic hydrocarbon; wherein the structural formula of the columnar aromatic hydrocarbon is shown below: n is 4, 5 or 6.

2. The method for preparing a composite membrane based on diethanolamine-functionalized columnar aromatics as described in claim 1, characterized in that, The structural formula of the columnar aromatic hydrocarbon is shown below: The synthesis process includes the following steps: S110, using 1,4-dibromobutane to react with hydroquinone to synthesize intermediate I, the structural formula of which is shown below: S120. Intermediate II is synthesized by reacting intermediate I with 1,4-dimethoxybenzene, with the structural formula shown below: S130. The columnar aromatic hydrocarbon is synthesized by reacting intermediate II with diethanolamine.

3. The method for preparing a composite membrane based on diethanolamine-functionalized columnar aromatics as described in claim 1, characterized in that, In step S100, the aqueous solution also contains a reaction promoter, which is selected from organic bases.

4. The method for preparing a composite membrane based on diethanolamine-functionalized columnar aromatics as described in claim 3, characterized in that, The organic base is selected from triethylamine, and the concentration of triethylamine is 0.8% (w / v) to 1.2% (w / v).

5. The method for preparing a composite membrane based on diethanolamine-functionalized columnar aromatics as described in claim 1, characterized in that, In step S100, the solvent of the aqueous solution is selected from a mixed solvent of water and N,N-dimethylacetamide, with a volume ratio of 1:

1.

6. The method for preparing a composite membrane based on diethanolamine-functionalized columnar aromatics as described in claim 1, characterized in that, In step S100, the acyl chloride monomer is selected from trimesoyl chloride, and the solvent of the organic phase solution is selected from n-hexane.

7. The method for preparing a composite membrane based on diethanolamine-functionalized columnar aromatics as described in claim 1, characterized in that, In step S200, the base film is selected from polyacrylonitrile film.

8. A composite membrane based on diethanolamine-functionalized columnar aromatics, characterized in that, It is prepared using the method for preparing a composite membrane based on diethanolamine functionalized columnar aromatics as described in any one of claims 1 to 7.

9. The application of composite membranes based on diethanolamine-functionalized columnar aromatics, characterized in that, The composite membrane based on diethanolamine functionalized columnar aromatics as described in claim 8 is used as a separation membrane, and the separation membrane is used for any one or more of the following:

1. separation of different antibiotics; 2. wastewater treatment containing antibiotics; 3. separation of different dyes; 4. wastewater treatment containing dye molecules; 5. wastewater treatment containing different antibiotics and different dye molecules.

10. The application of the composite membrane based on diethanolamine-functionalized columnar aromatics as described in claim 9, characterized in that, The antibiotic is selected from any one or at least two of the following: bacitracin, cefoperazone, and clindamycin phosphate; the dye is selected from any one or at least two of the following: crystal violet, methyl orange, methylene blue, methyl green, Congo red, Coomassie brilliant blue, and Alcian blue.

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