Simple low-consumption short-distance efficient preparation method of polyamide nanofiltration membrane and application
By using amino-hydroxy compounds to assist the interfacial polymerization reaction of ultra-low concentration piperazine, the high cost and environmental pollution problems caused by high concentration piperazine were solved, and low-consumption and high-efficiency preparation of polyamide nanofiltration membranes was achieved, thereby improving the separation performance and water permeability of the membrane.
Patent Information
- Application Number
- CN202511029574.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-25
- Publication Date
- 2025-10-17
AI Technical Summary
In the existing preparation method of polyamide composite nanofiltration membrane, high concentration of piperazine (PIP) leads to problems such as high cost, environmental pollution and poor membrane permeability.
Amino-hydroxy compounds are used as additives to assist the interfacial polymerization reaction of ultra-low concentration PIP through hydrogen bonding and electrostatic interactions to prepare polyamide nanofiltration membranes and form a uniform and complete active layer.
The amount of piperazine used is reduced, the risk of environmental pollution is reduced, the preparation cost is reduced, and the separation performance and water permeability of the membrane are improved.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of environmental science and engineering materials, and particularly relates to a simple and low-consumption method for short-range and efficient preparation of polyamide nanofiltration membranes and application thereof. BACKGROUND
[0002] With the increasing scarcity of global water resources, especially in some water-scarce regions, seawater desalination technology has gradually become one of the important means to solve the problem of freshwater shortage. Seawater desalination technology can convert seawater into potable freshwater and is widely used in agriculture, industry, and urban water supply fields. However, existing seawater desalination technologies face problems such as high energy consumption, high equipment cost, and unstable performance of membrane materials. In order to solve these problems, researchers have invested a lot of effort and resources in the research and development of membrane materials, optimization of membrane preparation processes, and other aspects in recent years.
[0003] In the process of seawater desalination, reverse osmosis membranes (RO membranes) and nanofiltration membranes (NF membranes) are commonly used separation materials. Compared with traditional reverse osmosis membranes, nanofiltration membranes can better retain minerals in water while removing smaller organic matter, ions, and other substances during the separation process. Therefore, nanofiltration membranes have wide application prospects in the fields of seawater desalination, wastewater treatment, food processing, and other fields. However, existing polyamide composite membranes (PA membranes) have some problems in the preparation process, especially in the balance between production cost and performance.
[0004] Currently, the commonly used preparation method of polyamide composite nanofiltration membranes is the interfacial polymerization process, that is, the polymerization reaction of water-phase monomers and organic-phase monomers occurs at the water / organic phase interface, and then a polyamide thin film is formed on the substrate surface. However, the traditional interfacial polymerization process often requires the use of relatively high concentrations (0.1% ~ 0.5% w / v) of water-phase reaction monomer substances (such as piperazine (PIP)), which not only increases the cost of membrane materials, but also may cause a series of problems such as environmental secondary pollution, personnel health, and other issues. In addition, a higher concentration of piperazine (PIP) often exhibits an uncontrollable diffusion rate, forming a thicker polyamide active layer, which leads to low water permeability and greatly increases the operating cost, which seriously limits the development of nanofiltration technology. SUMMARY
[0005] In view of this, the application provides a method for preparing a polyamide nanofiltration membrane with good separation performance by regulating ultra-low concentration PIP with an amino-hydroxyl compound additive and application, aiming to solve the problems of high membrane preparation cost and possible secondary pollution caused by the use of high concentration PIP in traditional interfacial polymerization PIP. By using the amino-hydroxyl compound additive as a water phase auxiliary agent that does not participate in the reaction but can regulate the diffusion rate of the water phase monomer, using the hydrogen bond interaction and electrostatic interaction between the hydroxyl functional group of the additive and the amino functional group on PIP, and using the hydrogen chloride (HCl) byproduct generated during the interfacial polymerization (IP) reaction to assist the amino-hydroxyl compound in carrying the PIP water phase monomer to the water / oil interface and participating in the reaction, the "short-range-high-efficiency" interfacial polymerization reaction can be carried out at an ultra-low concentration of 0.01% (w / v) PIP to prepare a polyamide nanofiltration membrane with a complete active layer and good nanofiltration membrane separation performance. Through this low-consumption and high-efficiency preparation method, the properties of the nanofiltration membrane are maintained, the production cost of the membrane is reduced, and the energy consumption is reduced, which is conducive to reducing the overall cost of seawater desalination nanofiltration pretreatment and provides a new idea for the efficient preparation of polyamide nanofiltration membranes. At the same time, it also provides a new strategy for the sustainable and green development of the seawater desalination industry.
[0006] The technical solution of the application is as follows: A simple and low-consumption short-range high-efficiency method for preparing a polyamide nanofiltration membrane, comprising the following steps: (1) The polyether sulfone ultrafiltration base film is cut, then the polyether sulfone ultrafiltration base film is ultrasonically cleaned with an ethanol solution, and then soaked in pure water to stabilize the film shape, to obtain a standby polyether sulfone ultrafiltration base film; (2) The standby polyether sulfone ultrafiltration base film treated in step (1) is fixed on a polytetrafluoroethylene frame with the film front face upward; (3) An amino-hydroxyl compound is mixed in an ultra-low concentration PIP solution to form a uniform water phase monomer solution, the water phase monomer solution is contacted with the front face of the base film fixed in step (2), then the remaining solution is poured out, the liquid remaining on the surface of the membrane is first absorbed, and then air is blown and naturally dried; (4) The membrane surface treated in step (3) is quickly poured into an n-hexane oil phase monomer solution containing triformylchloride to start the interfacial polymerization reaction, washed, heat treated, and cooled to obtain the prepared polyamide composite nanofiltration membrane, which is stored in pure water for use.
[0007] Further, in step (1), the polyether sulfone ultrafiltration base film is selected from polyether sulfone ultrafiltration membranes with a molecular weight cutoff of 30-35 kDa; the size of the cutting is 8-9 cm x 8-9 cm. By cutting to an appropriate size, it can be seamlessly fixed on a specially designed polytetrafluoroethylene (PTFE) frame.
[0008] Further, the polyether sulfone ultrafiltration membrane is provided by Microdyn-Nadir Company; and the polyether sulfone ultrafiltration membrane is stored in a light-proof sealed container before use.
[0009] Further, in step (1), the concentration of the ethanol solution is 1-2% (v / v); the ultrasonic cleaning time is 1-2 min each time, and the ethanol solution is replaced after each ultrasonic cleaning, and the process is repeated 2-3 times; and the standby polyether sulfone ultrafiltration base membrane is stored in pure water for at least 12 h before use.
[0010] Further, the specific operation of step (2) is as follows: the standby polyether sulfone ultrafiltration base membrane treated in step (1) is taken out of the pure water, and the membrane surface is gently blotted with filter paper until there is no obvious water droplets, then the membrane is fixed on a polytetrafluoroethylene frame with the front surface facing up, and naturally air-dried for 3-5 min, during which the membrane is uniformly air-blasted for 2-3 min with an air pump gun to ensure that a uniform dry-wet environment is provided in the base membrane pore channel.
[0011] Further, in step (3), the concentration of the amino-hydroxyl compound is 0.05-0.1% (w / v); the amino-hydroxyl compound is selected from one or more of 1,3-bis[tris(hydroxymethyl)methylamino]propane and tris(hydroxymethyl)aminomethane; the concentration of the ultra-low concentration PIP solution is 0.01-0.015% (w / v), which is the fixed main reaction monomer content; and the uniform aqueous phase reaction monomer solution needs to be uniformly mixed by ultrasonic and used in the same time period.
[0012] Further, in step (3), the contact time of the aqueous phase monomer solution with the front surface of the base membrane is 3-5 min; and the specific process of blotting the residual liquid on the membrane surface is as follows: the polyether sulfone ultrafiltration base membrane soaked in the aqueous phase reaction monomer solution is taken out of the fixed polytetrafluoroethylene frame and blotted with filter paper until there is no obvious water droplets, and this process is completed within 30 s.
[0013] Further, in step (3), the air blowing is uniformly air-blasted for 30-40 s with an air pump gun, and the polyether sulfone ultrafiltration base membrane soaked in the aqueous phase solution is quickly fixed on the polytetrafluoroethylene frame again; and the natural air-drying time is 2-3 min.
[0014] Further, in step (4), the concentration of the trimesoyl chloride n-hexane oil phase monomer solution is 0.1-0.2% (w / v); the interfacial polymerization reaction time is 30-40 s; the flushing is uniformly flushing 2-3 times with n-hexane solution after the trimesoyl chloride n-hexane oil phase monomer solution is poured out; the heat treatment is placing the membrane in an oven for heat treatment for 5-8 min; and the polyamide composite nanofiltration membrane is cooled to room temperature and soaked in pure water for at least 24 h before use.
[0015] Further, in step (4), the oil phase monomer solution containing 0.1-0.2% (w / v) trimesoyl chloride is quickly poured onto the surface of the membrane, and the soaking time is controlled at 30 s to quickly start the "short-range-high-efficiency" interfacial polymerization reaction, and the reaction byproduct hydrogen chloride during this period will assist the amino-hydroxyl compound to quickly carry the 0.01-0.015% (w / v) ultra-low concentration PIP solution to the reaction interface through hydrogen bonding and other interactions to participate in the IP reaction to form a complete polyamide nanofiltration membrane; then the oil phase monomer solution is poured off and quickly washed with n-hexane solution for two to three times to remove the excessive oil phase monomers remaining on the surface. After the above operation is completed, the prepared membrane is placed in an oven for heat treatment for 5-8 min to enhance the reaction crosslinking degree of the active layer and make the water phase monomer solution fully react, and then taken out and cooled to room temperature and soaked in pure water for at least 24 h before use.
[0016] The application of the polyamide nanofiltration membrane prepared by the simple and low-consumption short-range high-efficiency method for preparing the polyamide nanofiltration membrane of the application in water treatment.
[0017] Further, the application of the polyamide nanofiltration membrane of the application in salt separation performance and chlorine resistance test in water treatment.
[0018] The application of the polyamide nanofiltration membrane prepared by the simple and low-consumption short-range high-efficiency method for preparing the polyamide nanofiltration membrane of the application in seawater desalination, sewage treatment and drinking water purification.
[0019] PIP in the application refers to piperazine.
[0020] Compared with the prior art, the application has the following beneficial effects: (1) The application finds that 15 kinds of amino-hydroxyl compounds can be used as a kind of auxiliary additive. In the micro-chemical theory, the hydrogen bonding and electrostatic interaction between the hydroxyl functional groups of the amino-hydroxyl compounds and the amino functional groups on piperazine (PIP), and the hydrogen chloride (HCl) byproduct produced in the interfacial polymerization (IP) reaction process can assist the amino-hydroxyl compounds to carry the piperazine (PIP) water phase monomer to the water / oil interface and participate in the reaction by protonating the amino group on the amino-hydroxyl compound. Finally, the ultra-low concentration PIP water phase monomer is successfully used to prepare a polyamide nanofiltration membrane with good separation performance by using the carrying effect.
[0021] (2) The ultra-low piperazine (PIP) concentration used in the application is at least one order of magnitude lower than the traditional concentration, and the polyamide nanofiltration membrane with good nanofiltration performance is successfully prepared under the carrying effect of the amino-hydroxyl compound auxiliary.
[0022] (3) The polyamide nanofiltration membrane prepared by the application has a uniform and complete ultra-thin active layer due to the comprehensive effect of monomer concentration and reaction rate, the mass transfer resistance is reduced, and the water permeability of the membrane is enhanced.
[0023] (4) The nanofiltration membrane prepared by the application has a high sodium sulfate rejection rate and certain separation characteristics of monovalent and divalent salt. Meanwhile, the membrane surface is relatively smooth, has a high water flux, and maintains good performance and stable membrane performance in long-term operation.
[0024] (5) The application of 15 different types of auxiliary agents is verified to avoid contingency, and it is successfully proved that the short-range and high-efficiency interfacial polymerization for preparing the polyamide nanofiltration membrane is realized under the carrying effect of amino-hydroxyl compounds.
[0025] (6) The application results of 15 same types of additives show that the amino-hydroxyl compounds are proved to have universality for preparing the polyamide nanofiltration membrane. It is the first time to propose that the substances are applied to the preparation of the polyamide nanofiltration membrane with universality.
[0026] (7) According to the performance test of the 15 amino-hydroxyl compounds, it is concluded that the smaller the molecular weight is, the better the carrying effect is, which is conducive to further development.
[0027] (8) The control of the amount of monomer used in the reaction and the reaction time not only maintains good nanofiltration membrane properties, but also further reduces the cost of membrane preparation, which has a positive effect on the overall cost control of nanofiltration membrane pretreatment in seawater desalination engineering, and provides a new reference for the low-energy sustainable development of membrane technology.
[0028] The application adopts a kind of amino-hydroxyl compound additive with low concentration of 0.05% (w / v) as an auxiliary agent to complete the interfacial polymerization reaction of polyamide composite membrane together with piperazine (PIP) with ultra-low concentration of 0.01% (w / v). The polyamide composite nanofiltration membrane prepared by this method not only maintains high separation performance, but also greatly reduces the use amount of piperazine (PIP), thereby reducing the production cost of the membrane by at least 10 times or more. The breakthrough of this technology has important significance for reducing the material cost in the membrane separation process such as seawater desalination. In addition to the advantage in cost, the application also has obvious environmental friendliness. Since low-concentration PIP and additives are used, the amount of chemical reagents is reduced, and the risk of environmental pollution is reduced. At the same time, the energy consumption of the membrane preparation process is effectively controlled, further improving the sustainability of membrane production. Through this low-consumption and high-efficiency preparation method, not only the production cost of the membrane can be reduced, but also the separation performance of the membrane can be improved, so that it has more extensive application potential in the fields of seawater desalination, sewage treatment, drinking water purification and the like. The preparation technology of such membrane material provides a new idea for the seawater desalination industry, helps to reduce the overall cost of seawater desalination, improve the utilization rate of global water resources, and promote the further development of water treatment technology. BRIEF DESCRIPTION OF DRAWINGS
[0029] Figure 1 Scanning electron microscope (SEM) characterization images of the membranes prepared in Examples 1-6.
[0030] Figure 2 Atomic force microscope (AFM) characterization images of the 0.1P / TMC membrane prepared with higher PIP conventional concentration in Example 3-5, the 0.2P / TMC membrane prepared with higher PIP conventional concentration, and the 0.01P+0.05A / TMC membrane prepared with fixed ultra-low PIP concentration and amino-hydroxyl compound A as an auxiliary agent.
[0031] Figure 3 Water flux and separation performance tests of four kinds of conventional salts (Na2SO4, MgSO4, NaCl, MgCl2) of the polyamide nanofiltration membranes prepared according to the molecular weight from small to large under the carrying action of Example 2 and 15 kinds of amino-hydroxyl compound auxiliary agents including Example 5 and Example 6; the molecular weight size and interval of the 15 kinds of amino-hydroxyl compounds with sequence numbers A-O are included in the figure, the polyamide composite nanofiltration membrane of Example 5 has sequence number A, and the polyamide composite nanofiltration membrane of Example 6 has sequence number E. Water permeability in the figure is the Chinese name of water flux, and salt rejection in the figure is the Chinese name of salt removal rate.
[0032] Figure 4Specific names and molecular structure diagrams of the amino-hydroxy compounds A and E used in Example 5 and Example 6, respectively, under the carrying action of the amino-hydroxy compounds. DETAILED DESCRIPTION
[0033] In order to better understand the technical content of the present application, the following specific examples are provided to further illustrate the present application.
[0034] The experimental methods used in the embodiments of the present application are all conventional methods unless otherwise specified.
[0035] The materials, reagents, etc. used in the embodiments of the present application can be obtained from commercial channels unless otherwise specified.
[0036] Example 1 A polyamide composite nanofiltration membrane was prepared on a polyether sulfone (PES) ultrafiltration base membrane by interfacial polymerization (IP) reaction at room temperature (25°C).
[0037] The simple low-consumption short-range high-efficiency method for preparing a polyamide nanofiltration membrane of the present embodiment comprises the following steps: (1) The polyether sulfone (PES) ultrafiltration base membrane with a molecular weight cut-off (MWCO) of 30 kDa was cut into a size of 8 cm x 8 cm to ensure the uniform size and shape of the base membrane, and then the polyether sulfone (PES) ultrafiltration base membrane was ultrasonically cleaned twice for 2 min with an ethanol solution with a concentration of 1% (v / v), and the ethanol solution was replaced after each ultrasonic cleaning to remove glycerol protective agents or impurities on the membrane surface, and then the membrane was soaked in pure water to stabilize the membrane shape, and used after at least 12 h to obtain a standby polyether sulfone (PES) ultrafiltration base membrane; (2) The standby polyether sulfone (PES) ultrafiltration base membrane treated in step (1) was taken out of the pure water, and the membrane surface was gently blotted dry with filter paper until there were no obvious water droplets, then the membrane was fixed on a polytetrafluoroethylene (PTFE) frame with the front surface facing up, and naturally air-dried for 4 min, during which the membrane was uniformly air-blasted for 3 min with an air pump gun to obtain a polyether sulfone (PES) ultrafiltration base membrane; (3) Pure water without adding any monomer molecules was used as the aqueous phase reaction solution, and was brought into contact with the front surface of the polyether sulfone (PES) ultrafiltration base membrane of step (2) for 5 min, the polyether sulfone (PES) ultrafiltration base membrane soaked in the aqueous phase reaction monomer solution was taken out from the fixed polytetrafluoroethylene (PTFE) frame within 30 s and blotted dry with filter paper until there were no obvious water droplets, and then the membrane was uniformly air-blasted for 30 s with an air pump gun, and then the membrane was quickly fixed on a polytetrafluoroethylene (PTFE) frame again, and naturally air-dried for 2 min; (4) To the surface of the membrane treated in step (3), quickly pour the oil phase monomer solution containing 0.1% (w / v) trimesoyl chloride (TMC) in n-hexane to initiate the interfacial polymerization (IP) reaction, and the soaking time is controlled within 30 s to form a comparative membrane without an active layer. Pour off the oil phase monomer solution and quickly rinse the surface with n-hexane solution twice to remove the excess oil phase monomer remaining on the surface, and then place the prepared membrane in an oven for heat treatment for 8 min to stabilize the membrane morphology, thereby obtaining the prepared polyamide composite nanofiltration membrane (named: PES support), and then soak the membrane in pure water for at least 24 h before use.
[0038] Example 2 Example 2 is different from Example 1 in that a 0.01% (w / v) ultra-low concentration PIP solution is used as the main reaction monomer content as the aqueous phase reaction monomer solution, and the rest of the raw materials and preparation methods are the same.
[0039] A polyamide composite nanofiltration membrane is prepared on a polyether sulfone (PES) ultrafiltration base membrane by an interfacial polymerization (IP) reaction at room temperature (25°C).
[0040] The simple low-consumption short-range efficient method for preparing a polyamide nanofiltration membrane in this embodiment includes the following steps: (1) Cut the polyether sulfone (PES) ultrafiltration base membrane with a molecular weight cut-off (MWCO) of 30 kDa into a size of 8 cm x 8 cm to ensure the uniform size and shape of the base membrane, and then clean the polyether sulfone (PES) ultrafiltration base membrane with a 1% (v / v) ethanol solution twice for 2 min each time, and replace the ethanol solution after each ultrasonic cleaning to remove glycerol protective agents or impurities on the membrane surface, and then soak the membrane in pure water to stabilize the membrane morphology, and use it after at least 12 h to obtain a standby polyether sulfone (PES) ultrafiltration base membrane; (2) Take the standby polyether sulfone (PES) ultrafiltration base membrane treated in step (1) out of the pure water, and gently dab the membrane surface with filter paper until there is no obvious water droplet, then fix the membrane on a polytetrafluoroethylene (PTFE) frame with the front surface facing up, and naturally air dry for 4 min, and blow the membrane evenly with an air pump gun for 3 min during the drying process to obtain a polyether sulfone (PES) ultrafiltration base membrane; (3) The surface of the polyethersulfone (PES) ultrafiltration base membrane after soaking in the aqueous phase reaction monomer solution is taken out from the fixed polytetrafluoroethylene (PTFE) frame within 30 s and the membrane surface is blotted dry with filter paper until there is no obvious water droplets and is uniformly air blown with an air pump gun for 30 s, and then the membrane is quickly re-fixed to the polytetrafluoroethylene (PTFE) frame and naturally air-dried for 2 min; (4) The surface of the membrane treated in step (3) is quickly poured with an oil phase monomer solution containing 0.1% (w / v) trimesoyl chloride (TMC) in n-hexane for interfacial polymerization (IP) reaction, and the soaking time is controlled within 30 s to prepare a polyamide composite nanofiltration membrane with a non-intact active layer under a low aqueous phase monomer reaction concentration and a short reaction time. The oil phase monomer solution is poured off and uniformly washed twice with n-hexane solution to remove excess oil phase monomer remaining on the surface, and the prepared membrane is placed in an oven for heat treatment for 8 min to stabilize the active layer, enhance the reaction cross-linking degree, and make the aqueous phase monomer solution fully react, thereby obtaining the prepared polyamide composite nanofiltration membrane (named: 0.01P / TMC). After being taken out, it is cooled to room temperature and immersed in pure water for at least 24 h before use.
[0041] Example 3 Example 3 differs from Example 2 in that a higher conventional concentration of 0.1% (w / v) PIP solution is used as the main reaction monomer content as the aqueous phase reaction monomer solution, and the rest of the raw materials and preparation methods are consistent.
[0042] A polyamide composite nanofiltration membrane was prepared on a polyethersulfone (PES) ultrafiltration base membrane by interfacial polymerization (IP) reaction at room temperature (25°C).
[0043] The simple low-consumption short-range efficient preparation method of the polyamide nanofiltration membrane of the present embodiment comprises the following steps: (1) The polyethersulfone (PES) ultrafiltration base membrane with a molecular weight cut-off (MWCO) of 30 kDa is cut into a size of 8 cm x 8 cm to ensure the uniform size and shape of the base membrane, and then the polyethersulfone (PES) ultrafiltration base membrane is ultrasonically cleaned twice for 2 min with a 1% (v / v) ethanol solution, and the ethanol solution is replaced after each ultrasonic cleaning to remove glycerol protective agents or impurities on the membrane surface. Subsequently, the membrane is soaked in pure water to stabilize the membrane shape, and used after at least 12 h to obtain a standby polyethersulfone (PES) ultrafiltration base membrane; (2) The prepared polyether sulfone (PES) ultrafiltration base membrane after step (1) was taken out from the pure water, and the membrane surface was gently blotted dry with filter paper until no obvious water droplets were observed. Then, the membrane was fixed on a polytetrafluoroethylene (PTFE) frame with the front surface facing upwards, and naturally air-dried for 4 min. During this period, the membrane was uniformly air-blasted for 3 min using an air pump gun. Thus, a polyether sulfone (PES) ultrafiltration base membrane was obtained. (3) A higher conventional concentration of 0.1% (w / v) PIP solution was used as the main reaction monomer content as the aqueous phase reaction monomer solution, which was brought into contact with the front surface of the polyether sulfone (PES) ultrafiltration base membrane of step (2) for 5 min. The polyether sulfone (PES) ultrafiltration base membrane soaked in the aqueous phase reaction monomer solution was taken out from the fixed polytetrafluoroethylene (PTFE) frame within 30 s, and the membrane surface was blotted dry with filter paper until no obvious water droplets were observed. The membrane was then uniformly air-blasted for 30 s using an air pump gun, and then quickly re-fixed on the polytetrafluoroethylene (PTFE) frame and naturally air-dried for 2 min. (4) An oil phase monomer solution of trimesoyl chloride (TMC) with a concentration of 0.1-0.2% (w / v) in n-hexane was quickly poured onto the surface of the membrane treated in step (3) for interfacial polymerization (IP) reaction, and the soaking time was controlled within 30 s to prepare a polyamide composite nanofiltration membrane with an intact active layer under a higher conventional PIP concentration. The oil phase monomer solution was poured off and washed twice with n-hexane to remove excess oil phase monomer on the surface. The prepared membrane was placed in an oven for heat treatment for 8 min to stabilize the active layer, enhance the cross-linking degree of the reaction, and allow the aqueous phase monomer solution to fully react. Thus, a polyamide composite nanofiltration membrane (named: 0.1P / TMC) was obtained. After cooling to room temperature, the membrane was immersed in pure water for at least 24 h before use.
[0044] Example 4 The difference between Example 4 and Example 2 is that a higher conventional concentration of 0.2% (w / v) PIP solution was used as the main reaction monomer content, and the rest of the raw materials and preparation methods were the same.
[0045] A polyamide composite nanofiltration membrane was prepared on a polyether sulfone (PES) ultrafiltration base membrane by interfacial polymerization (IP) reaction at room temperature (25°C).
[0046] The simple, low-consumption, short-range and efficient method for preparing a polyamide nanofiltration membrane of the present example comprises the following steps: (1) The polyethersulfone (PES) ultrafiltration base membrane with a molecular weight cut-off (MWCO) of 30 kDa was cut into a size of 8 cm x 8 cm to ensure the uniform size and shape of the base membrane, and then the polyethersulfone (PES) ultrafiltration base membrane was ultrasonically cleaned twice for 2 min with an ethanol solution with a concentration of 1% (v / v), and the ethanol solution was replaced after each ultrasonic cleaning to remove glycerol protectant or impurities on the surface of the membrane, and then the membrane was soaked in pure water to stabilize the membrane shape, and used after at least 12 h, to obtain a standby polyethersulfone (PES) ultrafiltration base membrane; (2) The standby polyethersulfone (PES) ultrafiltration base membrane treated in step (1) was taken out of the pure water, and the membrane surface was gently blotted with filter paper until there was no obvious water droplets, then it was fixed on a polytetrafluoroethylene (PTFE) frame with the front surface facing up, and naturally air-dried for 4 min, during which it was uniformly air-blasted with an air pump gun for 3 min, to obtain a polyethersulfone (PES) ultrafiltration base membrane; (3) A higher conventional concentration of 0.2% (w / v) PIP solution was used as the main reaction monomer content as the aqueous phase reaction monomer solution, and it was brought into contact with the front surface of the polyethersulfone (PES) ultrafiltration base membrane in step (2) for 5 min, and the polyethersulfone (PES) ultrafiltration base membrane soaked in the aqueous phase reaction monomer solution was taken out from the fixed polytetrafluoroethylene (PTFE) frame within 30 s and blotted with filter paper until there were no obvious water droplets, and then it was uniformly air-blasted with an air pump gun for 30 s, and then it was quickly fixed to the polytetrafluoroethylene (PTFE) frame again, and naturally air-dried for 2 min; (4) A hexane oil phase monomer solution containing 0.1-0.2% (w / v) trimesoyl chloride (TMC) was quickly poured onto the surface of the membrane treated in step (3) to start the interfacial polymerization (IP) reaction, and the soaking time was controlled within 30 s to prepare a polyamide composite nanofiltration membrane with an intact active layer under a higher conventional PIP concentration, and the oil phase monomer solution was poured off and rinsed twice with hexane solution to remove excess oil phase monomer on the surface, and the prepared membrane was placed in an oven for heat treatment for 8 min to stabilize the active layer, enhance the reaction cross-linking degree, and make the aqueous phase monomer solution fully react, thereby obtaining the prepared polyamide composite nanofiltration membrane (named: 0.2P / TMC), which was taken out and cooled to room temperature, and then soaked in pure water for at least 24 h before use.
[0047] Example 5 The difference between Example 5 and Example 2 is that a 0.01% (w / v) ultra-low concentration of PIP solution is used as the main reaction monomer content, and an amino-hydroxyl compound: 1,3-bis[tris(hydroxymethyl)methylamino]propane (labeled as amino-hydroxyl compound A) with a concentration of 0.05% (w / v) is added as an auxiliary agent to form a uniform aqueous phase reaction monomer solution, and the rest of the raw materials and preparation methods are consistent.
[0048] A polyamide composite nanofiltration membrane was prepared on a polyethersulfone (PES) ultrafiltration base membrane by interfacial polymerization (IP) at room temperature (25℃).
[0049] The simple low-consumption short-range efficient method for preparing a polyamide nanofiltration membrane of the present embodiment includes the following steps: (1) Cut a polyethersulfone (PES) ultrafiltration base membrane with a molecular weight cut-off (MWCO) of 30 kDa into a size of 8 cm x 8 cm to ensure the uniform size and shape of the base membrane, and then perform two 2 min ultrasonic cleanings on the polyethersulfone (PES) ultrafiltration base membrane using an ethanol solution with a concentration of 1% (v / v), and replace the ethanol solution after each ultrasonic cleaning to remove glycerol protective agents or impurities on the membrane surface, and then soak the membrane in pure water to stabilize the membrane shape, and use it at least 12 h later to obtain a standby polyethersulfone (PES) ultrafiltration base membrane; (2) Take the standby polyethersulfone (PES) ultrafiltration base membrane treated in step (1) out of the pure water, and gently dab the membrane surface with filter paper until there are no obvious water droplets, then fix it on a polytetrafluoroethylene (PTFE) frame with the membrane facing upwards, and naturally air dry for 4 min, during which use an air pump gun to uniformly air blow it for 3 min to obtain a polyethersulfone (PES) ultrafiltration base membrane; (3) Fix a 0.01% (w / v) ultra-low concentration PIP solution as the main reaction monomer content, add a 0.05% (w / v) amino-hydroxyl compound: 1,3-bis[tris(hydroxymethyl)methylamino]propane as an auxiliary agent to form a uniform aqueous phase reaction monomer solution, and contact it with the surface of the polyethersulfone (PES) ultrafiltration base membrane of step (2) for 5 min, take the polyethersulfone (PES) ultrafiltration base membrane soaked in the aqueous phase reaction monomer solution out of the fixed polytetrafluoroethylene (PTFE) frame within 30 s, dab the membrane surface with filter paper until there are no obvious water droplets, and use an air pump gun to uniformly air blow it for 30 s, then quickly fix the membrane to the polytetrafluoroethylene (PTFE) frame again, and naturally air dry for 2 min; (4) Pour the oil phase monomer solution containing 0.1% (w / v) trimesoyl chloride (TMC) onto the surface of the membrane treated in step (3) rapidly, and soak for 30 s to quickly start the short-range and efficient interfacial polymerization (IP) reaction. During this period, the reaction byproduct hydrogen chloride (HCI) will help the amino-hydroxyl compound to quickly carry 0.01% (w / v) ultra-low concentration PIP to the reaction interface through hydrogen bonding and other interactions to participate in the IP reaction to form a complete polyamide composite nanofiltration membrane. Pour out the oil phase monomer solution and quickly rinse twice with n-hexane solution to remove excess oil phase monomers remaining on the surface. Then, place the prepared membrane in an oven for heat treatment for 8 min to stabilize the active layer, enhance the reaction cross-linking degree, and allow the water phase monomer solution to fully react, thereby obtaining the prepared polyamide composite nanofiltration membrane (named: 0.01P+0.05A / TMC). After taking it out, cool it to room temperature, and immerse it in pure water for at least 24 h before use.
[0050] Example 6 Example 6 differs from Example 2 in that the 0.01% (w / v) ultra-low concentration PIP solution is fixed as the main reaction monomer content, and the amino-hydroxyl compound tris(hydroxymethyl)aminomethane (labeled as amino-hydroxyl compound E) with a concentration of 0.05% (w / v) is added as an auxiliary agent to form a uniform water phase reaction monomer solution. The rest of the raw materials and preparation methods are consistent.
[0051] A polyamide composite nanofiltration membrane was prepared on a polyether sulfone (PES) ultrafiltration base membrane by interfacial polymerization (IP) reaction at room temperature (25°C).
[0052] The simple and low-consumption short-range and efficient method for preparing a polyamide nanofiltration membrane in this example includes the following steps: (1) Cut the polyether sulfone (PES) ultrafiltration base membrane with a molecular weight cut-off (MWCO) of 30 kDa into a size of 8 cm x 8 cm to ensure the uniform size and shape of the base membrane. Then, use a 1% (v / v) ethanol solution to ultrasonically clean the polyether sulfone (PES) ultrafiltration base membrane twice for 2 min each time, and replace the ethanol solution after each ultrasonic cleaning to remove glycerol protectants or impurities on the membrane surface. Then, immerse the membrane in pure water to stabilize the membrane shape for at least 12 h before use, thereby obtaining a standby polyether sulfone (PES) ultrafiltration base membrane; (2) Take the standby polyether sulfone (PES) ultrafiltration base membrane treated in step (1) out of the pure water, and gently dab the membrane surface with filter paper until there are no obvious water droplets. Then, fix the membrane on a polytetrafluoroethylene (PTFE) frame with the membrane facing upwards, and naturally air dry for 4 min. During this period, use an air pump gun to uniformly air blow the membrane for 3 min, thereby obtaining a polyether sulfone (PES) ultrafiltration base membrane; (3) Immersing the surface of the polyethersulfone (PES) ultrafiltration support membrane from step (2) into a uniform aqueous phase reaction monomer solution with a fixed 0.01% (w / v) ultra-low concentration of PIP as the main reaction monomer content and adding 0.05% (w / v) of an amino-hydroxyl compound, tris(hydroxymethyl)aminomethane, as an auxiliary agent for 5 min, and then taking the polyethersulfone (PES) ultrafiltration support membrane immersed in the aqueous phase reaction monomer solution out of the fixed polytetrafluoroethylene (PTFE) frame within 30 s, using filter paper to dry the membrane surface to no obvious water droplets, and then using an air pump gun to uniformly blow air onto the membrane surface for 30 s, and then quickly re-fixing the membrane to the polytetrafluoroethylene (PTFE) frame and naturally air-drying for 2 min; (4) Quickly pouring the n-hexane oil phase monomer solution containing 0.1% (w / v) trimesoyl chloride (TMC) onto the surface of the membrane treated in step (3) to quickly start a short-range and efficient interfacial polymerization (IP) reaction, and the reaction byproduct hydrogen chloride (HCl) during this period will help the amino-hydroxyl compound to quickly carry 0.01% (w / v) ultra-low concentration PIP to the reaction interface through hydrogen bonding and other interactions to participate in the IP reaction to form a complete polyamide composite nanofiltration membrane, pouring off the oil phase monomer solution and quickly washing the surface twice with n-hexane solution to remove excess oil phase monomers remaining on the surface, and then placing the prepared membrane in an oven for heat treatment for 8 min to stabilize the active layer, enhance the reaction cross-linking degree, and allow the aqueous phase monomer solution to fully react, thereby obtaining the prepared polyamide composite nanofiltration membrane (named: 0.01P+0.05E / TMC), and then taking it out and cooling it to room temperature, and then soaking it in pure water for at least 24 h before use.
[0053] Polyamide composite nanofiltration membrane characterization analysis and performance test 1. Scanning electron microscope (SEM) characterization analysis The polyamide composite nanofiltration membranes prepared in Examples 1-6 were subjected to scanning electron microscope (SEM) characterization analysis.
[0054] As shown in Figure 1 (a-f) are the surface morphology SEM characterization diagrams of the polyethersulfone ultrafiltration control membrane (PES support) prepared from the pure water phase reaction solution in Examples 1-6, the 0.01P / TMC membrane prepared from ultra-low PIP concentration, the 0.1P / TMC membrane prepared from higher PIP conventional concentration, the 0.2P / TMC membrane prepared from higher PIP conventional concentration, the 0.01P+0.05A / TMC membrane prepared by adding amino-hydroxyl compound A as an auxiliary agent under a fixed ultra-low PIP concentration, and the 0.01P+0.05E / TMC membrane prepared by adding amino-hydroxyl compound E as an auxiliary agent under a fixed ultra-low PIP concentration. By observing the scanning electron microscope characterization diagram, it can be seen thatFigure 1 As shown in (a, b), the surface morphology of the polyethersulfone ultrafiltration control membrane (PES support) prepared by the reaction of pure water phase reaction solution and the 0.01P / TMC membrane prepared by ultra-low PIP concentration is smooth without obvious nodules, confirming that they do not have the surface properties of the membrane with a complete active layer. Figure 1 As shown in (c, d), the 0.1P / TMC membrane prepared with a higher conventional PIP concentration and the 0.2P / TMC membrane prepared with an even higher conventional PIP concentration showed obvious particle nodules, indicating that the reaction at this concentration was more intense, and a conventional piperazine-based polyamide composite nanofiltration membrane was successfully prepared with a complete active layer. In addition, Figure 1 As shown in (e, f), the 0.01P+0.05A / TMC film and the 0.01P+0.05E / TMC film prepared by adding amino-hydroxy compounds as auxiliary agents at a fixed ultra-low PIP concentration have slight reaction traces and a small amount of nodules on the surface compared with the films prepared in the previous Examples 1-4, confirming that the amino-hydroxy compounds as auxiliary agents initiate the "short-range and efficient" interfacial polymerization reaction.
[0055] 2. Atomic force microscopy (AFM) characterization and analysis The polyamide composite nanofiltration membranes prepared in Examples 3-5 were characterized and analyzed using atomic force microscopy (AFM).
[0056] like Figure 2 (a-c) are shown, where a-c represent, respectively, the 0.1P / TMC membrane prepared at a higher conventional PIP concentration in Examples 3-5, the 0.2P / TMC membrane prepared at an even higher conventional PIP concentration, and the 0.01P+0.05A / TMC membrane prepared at a fixed ultra-low PIP concentration with the addition of amino-hydroxy compound A as an adjuvant. Atomic force microscopy revealed that the polyamide composite nanofiltration membrane prepared at conventional high PIP concentrations exhibited a high degree of surface roughness and relatively thick membrane thickness due to the high monomer concentration and vigorous reaction, which compromised membrane water flux. In contrast, the 0.01P+0.05A / TMC membrane prepared with the addition of amino-hydroxy compound A as an adjuvant exhibited a smoother and more intact membrane surface, consistent with the SEM characterization results, further confirming the efficient regulation of the amino-hydroxy compound as an adjuvant.
[0057] 3. Water flux and salt separation performance test The polyamide composite nanofiltration membrane prepared in Example 2 ( Figure 3polyamide composite nanofiltration membrane prepared in Example 5 and the polyamide composite nanofiltration membrane prepared in Example 6 and the polyamide composite nanofiltration membranes prepared in accordance with the preparation method of Example 6 by adding other 13 kinds of amino-hydroxy compounds with a concentration of 0.05% (w / v) as auxiliary agents at a fixed 0.01% (w / v) ultra-low PIP concentration Figure 3 The water flux and the removal rate of four kinds of conventional salts (Na2SO4, MgSO4, NaCl, MgCl2) of the polyamide composite nanofiltration membranes prepared in Examples 1-6 were tested in sequence according to the order of letters A-O, wherein the polyamide composite nanofiltration membrane of Example 5 is marked as A, the polyamide composite nanofiltration membrane of Example 6 is marked as E, and the results are shown in Table 1 and Figure 3 .
[0058] As Figure 3 shown above, the water flux of the polyamide composite nanofiltration membranes prepared above was tested under a pressure of 0.4 MPa by using cross-flow filtration. In order to obtain stable water flux, each membrane was pre-pressed by using deionized water at 0.5 MPa for at least 60 minutes before formal testing. In order to avoid contingency, each measurement was repeated three times and the average value was taken as the final result. The water flux of the membrane was calculated by using the formula F = J / A*t (F is the membrane flux; J is the sampling volume; A is the effective area of the membrane; t is the time). At the same time, the salt separation performance of the composite nanofiltration membranes prepared above was tested by using 1000 ppm Na2SO4, MgSO4, NaCl, MgCl2 salt solutions as the feed respectively under a pressure of 0.4 MPa. The conductivity of the salt solution before and after filtration was measured by using a conductivity meter, and the salt removal efficiency was obtained according to the ratio of the difference to the conductivity of the feed water. The measurement results were tested three times and the average value was taken. The application results of 15 kinds of the same type of additives including A and E showed that the amino-hydroxy compounds of this type were proved to be universal for preparing polyamide nanofiltration membranes. Finally, the ultra-low concentration PIP aqueous phase monomer was successfully used to prepare a polyamide nanofiltration membrane with good separation performance by using its carrying effect, and the auxiliary agent molecular weight was different, and the carrying effect was different.
[0059] Table 1 Water flux test results and salt separation test results of Examples 1-6
[0060] From the above Table 1 and Figure 3The results show that, compared with the commercially available NF270 nanofiltration membrane, the polyamide composite nanofiltration membrane prepared by the amino-hydroxyl compound auxiliary in the application examples 5 and 6 has a larger water flux than the NF270, and the membrane separation performance is realized under the condition that the auxiliary does not participate in the reaction, and the Na2SO4 removal rate is good, and the auxiliary molecule size and characteristics can be further developed and adjusted. In addition, compared with the polyamide composite nanofiltration membrane prepared by the amino-hydroxyl compound auxiliary in the application examples 5 and 6, the polyamide composite nanofiltration membrane has better monovalent / divalent salt separation performance. It can be seen that, under the carrying action of the amino-hydroxyl compound auxiliary (the molecular structures of the amino-hydroxyl compounds A and E are shown in Figure 4 ), the "short-range-high-efficiency" interfacial polymerization reaction of 0.01% (w / v) ultra-low concentration PIP is started, and the polyamide composite nanofiltration membrane is successfully prepared, and the prepared membrane has the advantages of high flux, high separation performance and simple operation, and has certain universality. This corresponds to the results of scanning electron microscope analysis in Figure 1 . The membrane prepared by the application examples 5 and 6 in Figure 1 has slight reaction marks and a small amount of nodules on the membrane surface, which proves that the amino-hydroxyl compound auxiliary starts the "short-range-high-efficiency" interfacial polymerization reaction, and under the premise of not forming a thick membrane rough surface by excessive reaction, it is beneficial to increase the water flux of the membrane, and at the same time has excellent salt separation performance.
[0061] Example 7 The polyamide composite nanofiltration membrane was prepared on the polyether sulfone (PES) ultrafiltration base membrane by interfacial polymerization (IP) reaction at room temperature (25°C).
[0062] The simple low-consumption short-range high-efficiency method for preparing the polyamide nanofiltration membrane in the embodiment includes the following steps: (1) The polyether sulfone (PES) ultrafiltration base membrane with a molecular weight cut-off (MWCO) of 35 kDa is cut into a size of 9 cm x 9 cm to ensure the uniform size and shape of the base membrane, and then the polyether sulfone (PES) ultrafiltration base membrane is washed with 1% (v / v) ethanol solution for three times, each time for 1 min, and the ethanol solution is replaced after each ultrasonic washing to remove the glycerol protective agent or impurities on the membrane surface, and then the membrane is soaked in pure water to stabilize the membrane shape, and used after at least 12 h to obtain the standby polyether sulfone (PES) ultrafiltration base membrane; (2) The standby polyether sulfone (PES) ultrafiltration base membrane treated in step (1) is taken out from the pure water, and the membrane surface is gently blotted with filter paper until there is no obvious water droplets, then the membrane is fixed on a polytetrafluoroethylene (PTFE) frame with the front surface facing up, and naturally air-dried for 5 min, and the membrane is uniformly air-blasted with an air pump gun for 3 min during the period to obtain the polyether sulfone (PES) ultrafiltration base membrane; (3) Immersing the surface of the polyethersulfone (PES) ultrafiltration base membrane from step (2) into a 0.015% (w / v) ultra-low concentration PIP solution as the main reaction monomer content, adding 0.1% (w / v) amino-hydroxyl compound A: 1,3-bis[tris(hydroxymethyl)methylamino]propane as an auxiliary agent to form a uniform aqueous phase reaction monomer solution, and contacting the solution with the surface of the polyethersulfone (PES) ultrafiltration base membrane for 4 min, taking the polyethersulfone (PES) ultrafiltration base membrane soaked in the aqueous phase reaction monomer solution out of the fixed polytetrafluoroethylene (PTFE) frame within 30 s, and using filter paper to wipe the membrane surface to remove obvious water droplets and use an air pump gun to uniformly blow air for 30 s, then quickly re-fix the membrane to the polytetrafluoroethylene (PTFE) frame, and naturally air dry for 2 min; (4) Quickly pouring a n-hexane oil phase monomer solution containing 0.2% (w / v) trimesoyl chloride (TMC) onto the membrane surface treated in step (3), and immersing for 40 s to quickly start the "short-range-high-efficiency" interfacial polymerization (IP) reaction, during which the reaction byproduct hydrogen chloride (HCI) will help the amino-hydroxyl compound to quickly carry 0.015% (w / v) ultra-low concentration PIP to the reaction interface through hydrogen bonding and other interactions to participate in the IP reaction to form a complete polyamide composite nanofiltration membrane, pouring off the oil phase monomer solution and quickly washing it with n-hexane solution three times to remove excess oil phase monomer remaining on the surface, and placing the prepared membrane in an oven for heat treatment for 6 min to stabilize the active layer, enhance the reaction cross-linking degree, and allow the aqueous phase monomer solution to fully react, thereby obtaining the prepared polyamide composite nanofiltration membrane (named: 0.01P+0.05A / TMC), and taking it out to cool to room temperature and soaking it in pure water for at least 24 h before use.
[0063] Example 8 A polyamide composite nanofiltration membrane was prepared on a polyethersulfone (PES) ultrafiltration base membrane by interfacial polymerization (IP) reaction at room temperature (25°C).
[0064] The simple low-consumption short-range high-efficiency method for preparing a polyamide nanofiltration membrane of this example includes the following steps: (1) Cutting a polyethersulfone (PES) ultrafiltration base membrane with a molecular weight cut-off (MWCO) of 30 kDa into a size of 9 cm x 9 cm to ensure the uniform size and shape of the base membrane, then washing the polyethersulfone (PES) ultrafiltration base membrane twice for 2 min with a 2% (v / v) ethanol solution, and replacing the ethanol solution after each ultrasonic treatment to remove glycerol protective agents or impurities on the membrane surface, and then soaking the membrane in pure water to stabilize the membrane shape, and using it after at least 12 h, to obtain a standby polyethersulfone (PES) ultrafiltration base membrane; (2) The standby polyether sulfone (PES) ultrafiltration base membrane treated in step (1) is taken out of the pure water, and the membrane surface is gently blotted dry with filter paper until there is no obvious water droplets, then it is fixed on a polytetrafluoroethylene (PTFE) frame with the membrane front facing up, and naturally air-dried for 3 min, during which it is uniformly air-blasted with an air pump gun for 2 min, to obtain a polyether sulfone (PES) ultrafiltration base membrane; (3) The concentration of 0.01% (w / v) ultra-low concentration PIP solution is fixed as the main reaction monomer content, and the concentration of 0.05% (w / v) amino-hydroxyl compound: tris (hydroxymethyl) aminomethane is added as an auxiliary agent to form a uniform aqueous phase reaction monomer solution, which is in contact with the front surface of the polyether sulfone (PES) ultrafiltration base membrane in step (2) for 3 min, and the polyether sulfone (PES) ultrafiltration base membrane soaked in the aqueous phase reaction monomer solution is taken out from the fixed polytetrafluoroethylene (PTFE) frame within 40 s and blotted dry with filter paper until there is no obvious water droplets, and then uniformly air-blasted with an air pump gun for 30 s, and then quickly re-fixed to the polytetrafluoroethylene (PTFE) frame, and naturally air-dried for 3 min; (4) A hexane oil phase monomer solution containing 0.2% (w / v) trimesoyl chloride (TMC) is quickly poured onto the membrane surface treated in step (3), and the soaking time is controlled within 40 s to quickly start the "short-range-high-efficiency" interfacial polymerization (IP) reaction, during which the reaction byproduct hydrogen chloride (HCl) will help the amino-hydroxyl compound to quickly carry 0.01% (w / v) ultra-low concentration PIP to the reaction interface through hydrogen bonding and other interactions to participate in the IP reaction to form a complete polyamide composite nanofiltration membrane, the oil phase monomer solution is poured off and quickly washed twice with hexane solution to remove excess oil phase monomers on the surface, and the prepared membrane is placed in an oven for heat treatment for 7 min to stabilize the active layer, enhance the reaction cross-linking degree, and make the aqueous phase monomer solution fully react, thereby obtaining the prepared polyamide composite nanofiltration membrane (named: 0.01P+0.05E / TMC), which is taken out and cooled to room temperature, and then soaked in pure water for at least 24 h before use.
[0065] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A simple, low-consumption, short-range and efficient method for preparing polyamide nanofiltration membranes, characterized in that: The following steps are involved: (1) cutting the polyethersulfone ultrafiltration base membrane, then ultrasonically cleaning the polyethersulfone ultrafiltration base membrane with an ethanol solution, and then immersing it in pure water to stabilize the membrane morphology, thereby obtaining a spare polyethersulfone ultrafiltration base membrane; (2) Fixing the spare polyethersulfone ultrafiltration base membrane treated in step (1) on a polytetrafluoroethylene frame with the front side of the membrane facing upward; (3) dissolving the amino-hydroxy compound in an ultra-low concentration piperazine solution to form a uniform aqueous phase reaction monomer solution, contacting the aqueous phase monomer solution with the front surface of the base film fixed in step (2), then gently pouring out the remaining solution, first drying the residual liquid on the surface of the film, then blowing air and letting it dry naturally; (4) The n-hexane oil phase monomer solution containing trimesoyl chloride is rapidly poured onto the membrane surface treated in step (3) to initiate the interfacial polymerization reaction, followed by rinsing, heat treatment, and cooling to obtain the prepared polyamide composite nanofiltration membrane, which is then stored in pure water for later use.
2. The method for preparing polyamide nanofiltration membrane in a simple, low-consumption, short-range and efficient manner according to claim 1, characterized in that: In step (1), the polyethersulfone ultrafiltration base membrane is selected from a polyethersulfone ultrafiltration membrane with a molecular weight cutoff of 30-35 kDa; the cut size is 8-9 cm×8-9 cm.
3. The method for preparing polyamide nanofiltration membrane in a simple, low-consumption, short-range and efficient manner according to claim 1, characterized in that: In step (1), the concentration of the ethanol solution is 1-2% (v / v); the ultrasonic cleaning time is 1-2 minutes each time, and the ethanol solution is replaced after each ultrasonic cleaning, and repeated 2-3 times; the spare polyethersulfone ultrafiltration base membrane is stored in pure water for at least 12 hours before use.
4. The method for preparing polyamide nanofiltration membrane in a simple, low-consumption, short-range and high-efficiency manner according to claim 1, characterized in that: The specific operation of step (2) is as follows: take out the spare polyethersulfone ultrafiltration base membrane treated in step (1) from the pure water, and gently wipe the surface of the membrane dry with filter paper until there are no obvious water droplets, then fix it on the polytetrafluoroethylene frame with the front side of the membrane facing up, and dry it naturally for 3-5 minutes, during which time use an air pump gun to blow air evenly for 2-3 minutes.
5. The method for preparing polyamide nanofiltration membrane in a simple, low-consumption, short-range and high-efficiency manner according to claim 1, characterized in that: In step (3), the concentration of the amino-hydroxy compound is 0.05-0.1% (w / v); the amino-hydroxy compound is selected from one or more of 1,3-bis[tris(hydroxymethyl)methylamino]propane and tris(hydroxymethyl)aminomethane; the concentration of the ultra-low concentration PIP solution is 0.01-0.015% (w / v), which is a fixed main reaction monomer content; the formation of a uniform aqueous phase reaction monomer solution requires ultrasonic mixing and is used in the same time period.
6. The method for preparing polyamide nanofiltration membrane in a simple, low-consumption, short-range and high-efficiency manner according to claim 1, characterized in that: In step (3), the contact time between the aqueous phase monomer solution and the front surface of the base membrane is 3-5 minutes; the specific process of drying the residual liquid on the surface of the membrane is as follows: the polyethersulfone ultrafiltration base membrane after soaking in the aqueous phase reaction monomer solution is taken out from the fixed polytetrafluoroethylene frame and the membrane surface is dried with filter paper until there are no obvious water droplets. This process is completed within 30 seconds.
7. The method for preparing polyamide nanofiltration membrane in a simple, low-consumption, short-range and high-efficiency manner according to claim 1, characterized in that: In step (3), the blowing is performed uniformly for 30-40 seconds using an air pump gun, and the polyethersulfone ultrafiltration base membrane soaked in the aqueous solution is quickly re-fixed on the polytetrafluoroethylene frame; the natural drying time is 2-3 minutes.
8. The method for preparing polyamide nanofiltration membrane in a simple, low-consumption, short-range and high-efficiency manner according to claim 1, characterized in that: In step (4), the concentration of the n-hexane oil phase monomer solution of trimesoyl chloride is 0.1-0.2% (w / v); the interfacial polymerization reaction time is 30-40s; the rinsing is to pour out the n-hexane oil phase monomer solution containing trimesoyl chloride and then quickly rinse it evenly with n-hexane solution 2-3 times; the heat treatment is to place the membrane in an oven for heat treatment for 5-8 minutes; the polyamide composite nanofiltration membrane is cooled to room temperature and soaked in pure water for at least 24 hours before use.
9. Use of the polyamide nanofiltration membrane prepared by the simple, low-consumption, short-range and high-efficiency method for preparing polyamide nanofiltration membrane according to any one of claims 1 to 8 in water treatment.
10. Use of the polyamide nanofiltration membrane prepared by the simple, low-consumption, short-range and high-efficiency method for preparing polyamide nanofiltration membrane according to any one of claims 1 to 8 in seawater desalination, sewage treatment and drinking water purification.