A pillar aromatic porous polymer membrane and its preparation method and oil-water separation application

Abstract

The present invention relates to the technical field of porous polymer preparation, and specifically to a pillar aromatic hydrocarbon porous polymer membrane, a preparation method thereof, and oil-water separation applications. The preparation method comprises the following steps: step 1, dissolving ligands NP5 and TOB in dichloromethane to form an organic phase; step 2, adding an aqueous phase to the upper layer of the organic phase, adding an acetic acid aqueous solution as a catalyst, and performing an interfacial polymerization reaction at room temperature to obtain an NP5-TOB polymer; step 3, dispersing the NP5-TOB polymer in dichloromethane to form a uniform dispersion; and step 4, using a vacuum-assisted assembly technique to load the NP5-TOB polymer dispersion on a nylon membrane surface to prepare an NP5-TOB / nylon composite membrane. The pillar aromatic hydrocarbon porous polymer membrane, the preparation method thereof, and the oil-water separation application of the present invention achieve efficient oil-water selective separation and have excellent anti-pollution performance and long-term stability.

Description

Technical Field

[0001] The present invention relates to the technical field of porous polymer preparation, in particular to a pillar aromatics porous polymer membrane and a preparation method and oil-water separation application thereof. Background Art

[0002] With the acceleration of industrialization and urbanization, oil-water pollution has become a significant global environmental issue. In particular, the discharge of oil-water mixed wastewater in industries such as petroleum, chemical, machinery manufacturing, and food processing seriously impacts water resource security and ecological health. To address this challenge, oil-water separation technology has been extensively researched and applied, becoming a key topic in environmental protection. Traditional oil-water separation methods include physical separation (such as sedimentation and flotation), chemical separation (such as adsorption and flocculation), and membrane separation. Membrane separation, due to its high efficiency, energy conservation, and sustainability, has become a research hotspot in oil-water separation technology. Currently, membranes used for oil-water separation include flat sheet membranes, hollow fiber membranes, and spiral wound membranes. Flat sheet membranes are widely used for experimental and small-scale separations due to their simple geometry and ease of processing, but their surface area is limited. Hollow fiber membranes, however, enjoy a significant position in industry due to their high specific surface area and low resistance. Oil-water separation membranes typically have pores ranging from micrometers to nanometers, and their surface properties can range from hydrophilic to oleophobic, or vice versa. The distribution and size of the pores directly determine the efficiency and selectivity of the separation. Most membrane materials separate oil-water mixtures based on differences in interfacial tension between liquids. For example, hydrophilic membranes allow water to pass through while blocking oil droplets, while hydrophobic membranes allow the oil phase to pass through while rejecting the water phase. The traditional process for preparing and using oil-water separation membranes involves preparing the membrane material. For example, polymer materials (such as polytetrafluoroethylene and polyamide) are used to create membranes with specific pore structures through phase separation, thermally induced phase separation, or coating techniques. Surface modification is then performed using plasma treatment, chemical modification, or coating with functional materials (such as polyethylene glycol and fluorides) to impart hydrophilic or oleophobic properties to the membrane material. During testing, the membrane material is fixed in place in the device, and the oil-water mixture is introduced into the membrane system by applying pressure or relying on gravity flow, achieving selective oil-water separation.

[0003] The shortcomings of existing oil-water separation technologies are: (1) limited separation efficiency, making it difficult to achieve efficient oil-water separation. Traditional separation methods such as gravity separation and centrifugal separation are not effective in processing fine oil droplets or emulsified oil, and have low separation efficiency; (2) serious membrane fouling problems and short service life. Oil-water separation membranes are easily contaminated by oil during use, resulting in clogging of membrane pores and decreased flux, requiring frequent cleaning or replacement, which increases operating costs; (3) complex operation and high maintenance costs. Existing oil-water separation membrane systems usually require complex pretreatment steps and regular chemical cleaning, which not only increases the complexity of operation but also increases maintenance costs. Therefore, in view of the above status quo, there is an urgent need to develop a pillar aromatics porous polymer membrane, its preparation method, and oil-water separation application to overcome the shortcomings in current practical applications. Summary of the Invention

[0004] The purpose of the present invention is to provide a pillar aromatic porous polymer membrane and a preparation method thereof and oil-water separation application, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing a pillararene porous polymer membrane comprises the following steps:

[0007] Step 1: dissolving the ligand NP5 and TOB in dichloromethane to form an organic phase;

[0008] Step 2: adding an aqueous phase to the upper layer of the organic phase, and adding an acetic acid aqueous solution as a catalyst, and performing an interfacial polymerization reaction at room temperature to obtain an NP5-TOB polymer;

[0009] Step 3, dispersing the NP5-TOB polymer in dichloromethane to form a uniform dispersion;

[0010] Step 4: Using vacuum-assisted assembly technology, the NP5-TOB polymer dispersion is loaded on the surface of the nylon membrane to prepare the NP5-TOB / nylon composite membrane.

[0011] As a further embodiment of the present invention: in steps 1 and 2, the molar ratio of NP5 to TOB is 1:1; and the concentration of the acetic acid aqueous solution is 2-3 M.

[0012] As a further solution of the present invention: in step 2, an appropriate amount of deionized water is slowly added to the upper surface of the DCM to establish a stable DCM / water interface, and then an appropriate amount of aqueous acetic acid is added to the upper aqueous phase, and interfacial polymerization occurs at the interface. The reaction is continued for 72 hours to obtain NP5-TOB polymer.

[0013] A pillararomatic porous polymer membrane is prepared by the preparation method described above, wherein the pillararomatic porous polymer membrane is an NP5-TOB / nylon composite membrane, composed of an NP5-TOB polymer supported on the surface of a nylon membrane; and the pillararomatic porous polymer membrane has superhydrophobic and superoleophobic properties; the membrane has the NP5-TOB polymer composition shown below:

[0014] .

[0015] As a further embodiment of the present invention: the underwater oil contact angle and the underwater water contact angle of the NP5-TOB polymer are both greater than 150°;

[0016] The membrane loading was 0.24-0.96 mg / cm².

[0017] A method for oil-water separation, using the pillararomatic porous polymer membrane described above, comprises the following steps:

[0018] Pre-wet the membrane according to the separation target. If the oil phase needs to be separated, pre-wet the membrane with oil; if the water phase needs to be separated, pre-wet the membrane with water;

[0019] installing the pre-wetted membrane in a separation device;

[0020] The oil-water mixture is poured into the separation device and a pressure of 0.5 bar is applied to drive the mixture through the membrane to achieve oil-water separation.

[0021] As a further embodiment of the present invention, the oil-water mixture is an oil-in-water emulsion or a water-in-oil emulsion.

[0022] As a further solution of the present invention: the oil in the oil-water mixture includes heavy oil and light oil, the heavy oil is dichloromethane or chloroform, and the light oil is n-hexane or petroleum ether.

[0023] An oil-water separation system comprises the pillar aromatics porous polymer membrane described above and an air pump device for applying pressure.

[0024] As a further solution of the present invention: the system is suitable for oil-water separation in oil fields, water treatment or petrochemical industries.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention achieves efficient selective separation of oil and water, has excellent anti-pollution performance and long-term stability, and can not only play a role in the separation of various oil-water mixtures, but also has the advantages of energy conservation and environmental protection. It is widely applicable to industries such as oil fields, water treatment and petrochemicals, thus providing an efficient, economical and sustainable solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a preparation route for NP5-TOB in an embodiment of the present invention.

[0028] Figure 2 Schematic diagram of the NP5-TOB / nylon composite membrane separating oil-water mixture in an embodiment of the present invention.

[0029] Figure 3 Schematic diagram of the contact angle of water in air, the contact angle of water in oil, and the contact angle of oil in water of the NP5-TOB / nylon film in an embodiment of the present invention.

[0030] Figure 4 This is a physical picture of the NP5-TOB / nylon composite membrane separating heavy oil / water and light oil / water in an embodiment of the present invention;

[0031] Among them, the upper side is a physical picture of separating heavy oil / water, and the lower side is a physical picture of separating light oil / water.

[0032] Figure 5 Schematic diagram of the preparation method and structure of the membrane in the embodiment of the present invention.

[0033] Figure 6 Schematic diagram of the permeability (a) and separation efficiency (b) of the NP5-TOB / nylon composite membrane for separating heavy oil / water and light oil / water in an embodiment of the present invention.

[0034] Figure 7 Schematic diagram of the transmittance (a) and separation efficiency (b) of the NP5-TOB / nylon composite membrane for separating oil-water emulsion in an embodiment of the present invention.

[0035] Figure 8 Schematic diagram of the cyclic stability of the NP5-TOB / nylon composite membrane for the separation of (a) dichloromethane (heavy oil) / water and (b) n-hexane (light oil) / water systems in an embodiment of the present invention.

[0036] Figure 9 Schematic diagram of the antifouling performance of the NP5-TOB / nylon composite membrane for separating (a) oil and (b) water in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0039] See also Figures 1-9 The pillararomatic porous polymer membrane of the present invention, its preparation method, and its application in oil-water separation can address the problems of existing oil-water separation materials in terms of efficiency, stability, and environmental adaptability. It can effectively improve the efficiency of oil-water separation, and has good reusability and high separation selectivity, making it particularly suitable for treating complex oil-water mixtures. The specific synthesis route and detection process are as follows:

[0040] 1. Structure and preparation route of NP5-TOB:

[0041] like Figure 1 As shown, the present invention prepared NP5-TOB via the following synthetic route. Two ligands, hydrazide-functionalized pillar-5 arene (NP5) and 2,4,6-tris(4-formylphenoxy)-1,3,5-triazine (TOB), were dissolved in dichloromethane (DCM). Then, aqueous phase was added to the top layer, along with a 2 M aqueous solution of acetic acid (AcOH). Polymerization was carried out at room temperature for three days to obtain the NP5-TOB polymer. The hydrazide-functionalized pillar-5 arene was first prepared by reacting paraformaldehyde and 1,4-dimethoxybenzene to obtain methoxy pillar-5 arene, followed by post-modification. 2,4,6-tris(4-formylphenoxy)-1,3,5-triazine was synthesized by reacting p-hydroxybenzaldehyde with cyanuric chloride in the presence of a phase transfer catalyst at room temperature for 24 hours. The reaction was then washed with alkali, dried, distilled under reduced pressure, and recrystallized from ethyl acetate to obtain a white solid product.

[0042] 2. Preparation process of oil-water separation membrane:

[0043] The synthesized NP5-TOB polymer was dispersed in DCM solvent to form a uniform dispersion. Next, using vacuum-assisted assembly technology (a simple and efficient membrane construction method that uses negative pressure to uniformly deposit functional materials from the dispersed phase onto the substrate surface), the NP5-TOB polymer dispersion was filtered under a 1 bar vacuum condition, resulting in uniform deposition of the material on the nylon substrate surface, achieving controllable loading. This composite membrane combines the functionality of the NP5-TOB polymer with the mechanical stability of a nylon membrane, providing an ideal material foundation for efficient oil-water separation.

[0044] 3. Oil-water separation process:

[0045] First, the separation membrane is pre-wetted to ensure the wettability of the membrane surface. Subsequently, an oil-water mixture containing heavy oil (such as DCM and chloroform) or light oil (such as n-hexane and petroleum ether) is introduced into the separation system. For water-in-oil emulsions and oil-in-water emulsions, they are also processed through a pre-wetted membrane. During the separation process, a pressure of 0.5 bar is applied by a vacuum pump to drive the mixture through the separation membrane. Due to the special structure and surface properties of the membrane, if water is used for pre-wetting, the water phase can pass through the membrane pores smoothly, while the oil phase is effectively retained. If oil is used for pre-wetting, the oil phase can pass through the membrane pores smoothly, while the water phase is effectively retained, thereby achieving efficient oil-water separation (such as Figure 2 (as shown). Heavy oil and light oil exhibit different permeability characteristics during the separation process due to differences in density and polarity, but both can be effectively separated by the membrane. The entire process is simple to operate, with high separation efficiency. The membrane's remarkable anti-fouling properties make it suitable for separating a wide range of oil-water mixtures.

[0046] The technical solution for oil-water separation is described as follows: The separation performance of the NP5-TOB / nylon composite membrane mainly depends on the special wettability behavior of its surface. Since the underwater oil contact angle and the oil-water contact angle of the NP5-TOB polymer are both over 150°, it exhibits superoleophobic and superhydrophobic properties, so the membrane can achieve selective separation according to the pre-wetting conditions. Specifically, when the membrane is pre-wetted with oil, a hydrophobic layer is formed on the membrane surface, and the oil phase can pass through the membrane pores, while the water phase is effectively retained; conversely, when the membrane is pre-wetted with water, an oleophobic layer is formed on the membrane surface, and the water phase can pass through the membrane pores, while the oil phase is effectively blocked (such as Figure 3 This selective wetting behavior is the core mechanism behind the efficient oil-water separation achieved by the NP5-TOB / nylon composite membrane. Furthermore, the unique chemical structure of the NP5-TOB polymer and its stable bond with the nylon membrane further enhance the membrane's separation efficiency and anti-fouling properties, enabling its widespread application in a variety of oil-water mixture separation scenarios.

[0047] The process of separating oil-water mixture is as follows:

[0048] (1) First, the NP5-TOB / nylon composite membrane is pre-wetted according to the separation target. If the oil phase needs to be separated, the membrane is pre-wetted with oil; if the water phase needs to be separated, the membrane is pre-wetted with water. After pre-wetting, the membrane is firmly installed in the separation device to ensure that it is stable and leak-free. This step is the foundation of the separation process, and the pre-wetting conditions directly determine the membrane's selective separation performance.

[0049] (2) Take 20 mL of oil (such as dichloromethane and n-hexane) and 20 mL of water and slowly pour the mixture into the separation device. In this step, due to the difference in density between the oil and water, the mixture will naturally separate into layers.

[0050] (3) Connect the air pump (output pressure range is 0.1-1 bar, gas flow range is 5-100 L / min), adjust the pressure to 0.5 bar, start the air pump to drive the oil-water mixture through the NP5-TOB / nylon membrane. Under the action of pressure, the oil phase or water phase selectively passes through the membrane pores according to the pre-wetting conditions of the membrane, while the other phase is effectively retained. After the separation is completed, the oil phase or water phase that passes through the membrane and the retained phase are collected separately to achieve efficient separation of the oil-water mixture (such as Figure 4 shown).

[0051] Example 1: Preparation of NP5-TOB: NP5 (0.13 g, 0.15 mmol) and TOB (0.066 g, 0.15 mmol) were dissolved in DCM (25.0 mL) at room temperature. Deionized water (25.0 mL) was then slowly added to the upper surface of the DCM to establish a stable DCM / water interface. Acetic acid (3 M aqueous solution, 2.0 mL) was then added to the upper aqueous phase as a catalyst. Interfacial polymerization began at this point, and polymer formation became clearly visible after 72 hours. After washing with water and DCM, the upper aqueous phase and lower organic phase were removed to yield NP5-TOB (0.23 g, 92% yield), a white solid.

[0052] Example 2: Preparation of NP5-TOB / nylon membrane: NP5-TOB was first uniformly dispersed in DCM to prepare an NP5-TOB dispersion. After ultrasonic treatment for 5 min, NP5-TOB was successfully loaded onto a nylon substrate using a vacuum-assisted assembly method to obtain an NP5-TOB / nylon membrane.

[0053] Example 3: Oil-Water Mixture Separation Experiment: First, the NP5-TOB / nylon composite membrane was pre-wetted according to the separation requirements. If the oil phase was to be separated, an oil-pre-wetted membrane was used; if the water phase was to be separated, a water-pre-wetted membrane was used. After pre-wetting, the membrane was securely mounted in the separation device, ensuring its stable position and no leakage. This is a critical step for ensuring effective separation. Next, 20 mL of oil (such as dichloromethane or n-hexane) was mixed with 20 mL of water and slowly poured into the separation device. An air pump was then connected and the pressure was adjusted to 0.5 bar. The pump was then activated to drive the oil-water mixture through the NP5-TOB / nylon membrane. The membrane's pre-wetting conditions determined the selective passage of either the oil or water phase, while effectively retaining the other phase. After separation, the oil or water phase that passed through the membrane and the retained phase were collected separately, achieving efficient oil-water separation.

[0054] Example 4: Oil-water mixture separation performance;

[0055] The present invention tests the separation performance of NP5-TOB / nylon composite membrane on four oil-water mixture systems: n-hexane / water, petroleum ether / water, dichloromethane / water and chloroform / water (e.g. Figure 6 The results show that the -2 Within the range of loading capacity, the separation efficiency of the membrane for heavy oil / water system exceeds 98% (up to 99.83%), of which 0.72 mg cm -2 The supported membrane achieved a separation efficiency of over 99% for all oil-water systems. -2 The loaded membrane exhibits ultrahigh flux in the separation of light oil / water systems.

[0056] Example 5: Oil-water emulsion separation performance;

[0057] The present invention tests the NP5-TOB / nylon composite membrane (loading capacity 0.72 mg cm -2 ) for the separation performance of oil-in-water emulsion and water-in-oil emulsion. When the loading amount increased to 0.96 mg cm -2 The separation efficiency was further improved when the ions were added, but the flux decreased, and the loading capacity decreased to 0.24–0.48 mg cm -2 The throughput is increased and the separation efficiency is maintained at 90% (e.g. Figure 7 The present invention achieves efficient and controllable separation of the emulsion by optimizing the active component loading, which is significantly superior to the prior art.

[0058] Example 6: Cyclic stability of membrane;

[0059] The present invention embodiment verifies the NP5-TOB / nylon composite membrane (loading capacity 0.72 mgcm -2 ) Cyclic stability of dichloromethane (heavy oil) / water and n-hexane (light oil) / water systems. Data show that after 50 consecutive separations, the membrane separation efficiency remains above 99%, and the flux loss is negligible (e.g. Figure 8 The membrane's structural integrity and separation performance demonstrate excellent durability over long-term use. In particular, after the 50th cycle, the separation efficiency of the oil-water mixture reached 99%. Its cyclic stability significantly outperformed conventional separation membranes, fully meeting the stringent requirements for long-term material stability in industrial applications.

[0060] Example 7: Antifouling performance test;

[0061] The present invention demonstrated the material's antifouling properties by dipping the membrane in water or oil at an angle and then dripping the oil or water. The tests confirmed that the NP5-TOB / nylon composite membrane exhibited excellent antifouling properties, with both oil and water rolling off the membrane quickly.

[0062] Example 8: Comparison with existing membrane performance;

[0063] Table 1. Performance comparison with reported membranes

[0064]

[0065] The present invention compares the separation membranes reported in the literature (Table 1) and confirms that the NP5-TOB / nylon composite membrane has high flux (4858.35 L m -2 h -1 ) and high separation efficiency (greater than 99%). Its flux and separation efficiency are significantly improved compared to similar materials, and it exhibits cyclic stability. The structural design of this pillararomatic functionalized membrane breaks through the trade-off between permeability and selectivity of traditional materials, providing an innovative solution for large-scale applications in environmental remediation and industrial separations.

[0066] It should be noted that, in the present invention, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only independent technical solutions. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a pillararene porous polymer membrane, characterized in that: The following steps are involved: Step 1: dissolve the ligand NP5 (hydrazide-functionalized column 5 aromatic hydrocarbon) and TOB (2,4,6-tris(4-formylphenoxy)-1,3,5-triazine) in dichloromethane to form an organic phase; Step 2: adding an aqueous phase to the upper layer of the organic phase, and adding an acetic acid aqueous solution as a catalyst, and performing an interfacial polymerization reaction at room temperature to obtain an NP5-TOB polymer; Step 3, dispersing the NP5-TOB polymer in dichloromethane to form a uniform dispersion; Step 4: Using vacuum-assisted assembly technology, the NP5-TOB polymer dispersion is loaded on the surface of the nylon membrane to prepare the NP5-TOB / nylon composite membrane.

2. The method for preparing a pillararene porous polymer membrane according to claim 1, wherein: In steps 1 and 2, the molar ratio of NP5 to TOB is 1:1; and the concentration of the acetic acid aqueous solution is 2-3 M.

3. The method for preparing a pillararene porous polymer membrane according to claim 1, wherein: In step 2, an appropriate amount of deionized water was slowly added to the upper surface of the DCM to establish a stable DCM / water interface. Then, an appropriate amount of aqueous acetic acid was added to the upper aqueous phase. Interfacial polymerization occurred at the interface and the reaction was continued for 72 hours to obtain NP5-TOB polymer.

4. A pillararene porous polymer membrane, characterized in that Prepared by the preparation method of claim 1, the pillar aromatic hydrocarbon porous polymer membrane is an NP5-TOB / nylon composite membrane, composed of an NP5-TOB polymer supported on the surface of a nylon membrane; and the pillar aromatic hydrocarbon porous polymer membrane has superhydrophobic and superoleophobic properties; the membrane has the NP5-TOB polymer composition shown below: 。 5. The pillararene porous polymer membrane according to claim 4, characterized in that The underwater oil contact angle and the underwater water contact angle of the NP5-TOB polymer are both greater than 150°; The membrane loading was 0.24-0.96 mg / cm².

6. An oil-water separation method, characterized in that: The pillararene porous polymer membrane according to claim 4 or 5 comprises the following steps: Pre-wet the membrane according to the separation target. If the oil phase needs to be separated, pre-wet the membrane with oil; if the water phase needs to be separated, pre-wet the membrane with water; Installing the pre-wetted membrane in a separation device; The oil-water mixture is poured into the separation device and a pressure of 0.5 bar is applied to drive the mixture through the membrane to achieve oil-water separation.

7. The oil-water separation method according to claim 6, characterized in that: The oil-water mixture is an oil-in-water emulsion or a water-in-oil emulsion.

8. The oil-water separation method according to claim 6, characterized in that: The oil in the oil-water mixture includes heavy oil and light oil, the heavy oil is dichloromethane or chloroform, and the light oil is n-hexane or petroleum ether.

9. An oil-water separation system, characterized in that: The invention comprises the pillar aromatic hydrocarbon porous polymer membrane according to claim 4 or 5, and an air pump device for applying pressure.

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