A polyamide thin layer composite membrane, a preparation method and application thereof

Abstract

The application provides a preparation method of a polyamide thin-layer composite film, characterized by comprising the following steps: pretreating a base film, adsorbing amino active groups on the surface of the pretreated base film; placing the base film under a base film reaction chamber after taking the base film out of a solution; introducing a microwave-vaporized organic phase solution containing a polyacyl chloride into the base film reaction chamber, and generating a vapor / liquid interface polymerization reaction between the vaporized organic phase solution and the base film; and performing heat treatment on the film material after the reaction, so as to finally obtain a polyamide thin-layer composite film product. The preparation method of the polyamide thin-layer composite film can more finely control the polymerization process and adjust the structural performance of the film. The utilization rate of the solvent is improved, the environmental pollution is reduced, and meanwhile, the process efficiency and the result reproducibility are ensured. The application further provides a polyamide thin-layer composite film and an application thereof.

Description

Technical Field

[0001] This invention belongs to the field of water treatment membrane technology, specifically, it relates to a polyamide thin-film composite membrane, its preparation method, and its application. Background Technology

[0002] Membrane separation technology, as a highly efficient, energy-saving, and environmentally friendly wastewater treatment method, has broad application prospects in the field of wastewater treatment. Among them, polyamide thin-layer composite membranes, with their excellent separation performance (high separation efficiency and flux) and good chemical resistance and durability, have become key technical materials in water treatment processes such as seawater desalination and wastewater reuse.

[0003] Polyamide thin-layer composite membranes can flexibly adapt to various separation needs and play an important role in the water treatment industry. Currently, the mainstream preparation process for polyamide thin-layer composite membranes is liquid / liquid interface polymerization. This technology involves sequentially immersing a porous base membrane in an aqueous solution containing a certain concentration of amine monomers and an organic solution containing a certain concentration of acyl chloride monomers. The two monomers then undergo a condensation reaction at the aqueous / organic phase interface, ultimately forming a polyamide separation layer with nanopores.

[0004] Although conventional liquid / liquid interface polymerization technology has a simple preparation process, it has the following problems: the amount of volatile organic solvent used is large, the utilization rate is low, and it is easy to cause environmental pollution. At the same time, the polymerization reaction between amine monomers and acyl chloride monomers is difficult to control the reaction rate, often forming a highly crosslinked and thick separation layer with a wide pore size distribution, which is prone to defects. Summary of the Invention

[0005] The purpose of this invention is to provide a polyamide thin-film composite film, its preparation method, and its application, aiming to solve the technical problem that the existing polyamide thin-film composite film preparation methods are difficult to control in terms of reaction process, which can easily affect product quality.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for preparing a polyamide thin-film composite film, comprising the following steps:

[0007] The base film is pretreated, and amino active groups are adsorbed on the surface of the pretreated base film;

[0008] After removing the base membrane from the solution, place it below the base membrane reaction chamber;

[0009] The organic phase solution containing polyacryl chloride is microwave-vaporized and then introduced into the base membrane reaction chamber. The vaporized organic phase solution and the base membrane undergo a vapor / liquid interface polymerization reaction.

[0010] The membrane material after the reaction is subjected to heat treatment to finally obtain a polyamide thin-film composite membrane product.

[0011] Preferably, the pretreatment of the base film, wherein the surface of the pretreated base film adsorbs amino active groups, includes: immersing the base film in an aqueous solution containing amine compounds, wherein the amine compounds contained in the aqueous solution are one or more of m-phenylenediamine, p-phenylenediamine, piperazine, ethylenediamine, hexamethylenediamine, polyethyleneimine, polyaniline, and polyo-phenylenediamine.

[0012] Preferably, the amine monomer in the aqueous solution has a mass percentage of 0.05-2%.

[0013] Preferably, the organic phase solution containing polyacryl chloride is microwave-vaporized and then introduced into the base membrane reaction chamber, wherein the polyacryl chloride contained in the organic phase solution is one or more of pyromellitic trimethylolpropionate chloride, terephthaloyl chloride, phthaloyl chloride, pyromellitic tetramethylolpropionate chloride, adipyl chloride, and malonyl chloride.

[0014] Preferably, the mass percentage of polyacrylamide chloride in the organic phase solution is 0.05-2%.

[0015] Preferably, the organic phase solution containing polyacrylamide chloride is microwave-vaporized and then introduced into the base membrane reaction chamber. The vaporized organic phase solution and the base membrane produce a vapor / liquid interface polymerization reaction. This includes: when microwave vaporization occurs, the size, flow rate, concentration and uniformity of the vapor molecules during the reaction are controlled by adjusting one or more of the following: atomizer power, rate, pore opening size, atomization direction and angle.

[0016] Preferably, the heat treatment of the reacted membrane material to obtain the polyamide thin-film composite membrane product includes: a heat treatment temperature of 60℃-100℃ and a time of 15-50min.

[0017] Preferably, the base membrane is a porous microfiltration membrane or an ultrafiltration membrane.

[0018] A polyamide thin-film composite film is prepared according to the preparation method of polyamide thin-film composite film as described in any one of the above.

[0019] A polyamide thin-layer composite membrane is prepared according to any of the methods described above, and / or the application of a polyamide thin-layer composite membrane in reverse osmosis and nanofiltration in water treatment is described above.

[0020] The beneficial effects of the polyamide thin-layer composite membrane preparation method provided by this invention are as follows: Compared with the prior art, the preparation method of this invention, by reacting gaseous monomers and liquid monomers at the gas / liquid interface, and by adjusting the atomizer power, rate, pore opening size, atomization direction and angle, can precisely control the size, flow rate, concentration, and uniformity of vapor molecules during the reaction, thereby regulating the polymerization process in the desired direction and optimizing the structure and performance of the polyamide thin-layer composite membrane. This method is simple, requires low-level equipment, and is inexpensive. It also improves solvent utilization, reduces environmental pollution, and ensures high efficiency and high reproducibility of the results. The obtained polyamide thin-layer composite membrane can be used as a nanofiltration membrane or a reverse osmosis membrane depending on the required application. This invention also provides a polyamide thin-layer composite membrane and its applications. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic flowchart of a method for preparing a polyamide thin-film composite film provided in an embodiment of the present invention;

[0023] Figure 2 A schematic diagram illustrating the principle of the method for preparing a polyamide thin-film composite film provided in the embodiments of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] The following description, in conjunction with the accompanying drawings, details a polyamide thin-film composite film, its preparation method, and its applications, provided by the embodiments of this application, through specific examples and application scenarios.

[0026] The polysulfone-based membrane used in the following examples is a commercially available membrane. The membrane was immersed in a 99.9% ethanol solution before use. Before the interfacial reaction to prepare the composite membrane, the polysulfone-based membrane was immersed in pure water for 24 hours. It should be further noted that in this invention, the membrane can be from any manufacturer; differences in membrane performance and type do not directly affect the results of the invention. Therefore, commercially available membranes or self-made membranes can be selected, which makes the invention universally applicable and commercially viable. Specifically, the membrane is a porous microfiltration membrane or an ultrafiltration membrane. More specifically, the membrane is one of the following: polysulfone membrane, polyethersulfone membrane, polyacrylonitrile membrane, polyvinylidene fluoride membrane, polypropylene membrane, or polyethylene membrane.

[0027] Please refer to the following: Figures 1 to 2 The present invention will now describe a method for preparing a polyamide thin-film composite film. The method for preparing the polyamide thin-film composite film includes the following steps:

[0028] Step S1: Pre-treat the base film. After pre-treatment, amino active groups are adsorbed onto the surface of the base film. Specifically, the base film is thoroughly immersed in an aqueous solution containing amine compounds.

[0029] In this step, the base membrane is first soaked in a 99.9% pure ethanol solution for 12-24 hours to remove impurities. Then, the base membrane is removed and soaked in deionized water for 1-3 hours to further clean the surface of residual ethanol and other impurities for subsequent use. Next, the base membrane is soaked in an aqueous solution containing at least one amine compound for 12-20 hours to allow amino active groups to adsorb onto its surface.

[0030] The aqueous solution in step S1 contains one or more of the following amine compounds: m-phenylenediamine, p-phenylenediamine, piperazine, ethylenediamine, hexamethylenediamine, polyethyleneimine, polyaniline, and polyo-phenylenediamine. The mass percentage of the amine monomer in the aqueous solution is 0.05-2%.

[0031] Step S2: After removing the base film from the solution, fix the base film with a special acrylic plate and let the surface solution air dry naturally, then place it under the base film reaction chamber.

[0032] Step S3: The organic phase solution containing polyacrylamide chlorides is microwave-vaporized and then introduced into the base membrane reaction chamber to undergo a vapor / liquid interfacial polymerization reaction. The polyacrylamide chlorides in the organic phase solution are one or more of the following: trimesoyl pyromellitic chloride, terephthaloyl chloride, phthaloyl chloride, tetramethylpyromellitic chloride, adipyl chloride, and malonyl chloride. The mass percentage of the polyacrylamide chlorides in the organic phase solution is 0.05-2%.

[0033] In this step, the vapor / liquid interface polymerization can be implemented in the following ways:

[0034] Step S3.1: After the base film is removed from the solution, it is placed between two specially made acrylic plates and fixed. After standing for 1-5 minutes, the excess liquid on the surface of the film is removed.

[0035] Step S3.2: Fix the base membrane horizontally below the base membrane reaction chamber, with the side to be reacted facing upwards. A circular opening with a diameter of 2.2 cm is opened in the center of the top of the reaction chamber to facilitate the entry of polyacrylamide chloride vapor into the reaction chamber after microwave vaporization, where a vapor / liquid interface reaction occurs on the upper surface of the base membrane.

[0036] Step S3.3: Use an atomizer to microwave vaporize the organic phase solution of polyacryl chloride for 1-4 minutes.

[0037] Step S3.4: Polyacrylamide chloride vapor enters the base membrane from the upper bottom circular hole to the lower bottom surface, thus entering the pores of the base membrane and undergoing vapor / liquid interfacial polymerization.

[0038] Step S4: The reacted membrane material is heat-treated at a certain temperature to finally obtain a polyamide thin-film composite membrane. The heat treatment temperature of the polyamide thin-film composite membrane is 60℃-100℃, and the time is 20-40min.

[0039] This invention provides a polyamide thin-layer composite membrane and its preparation method. Compared with existing technologies, this method allows for the selection of ultrafiltration membranes with larger pore sizes and higher permeability as the supporting substrate, effectively expanding the applicability of the thin-layer composite membrane and improving membrane flux. Compared to the liquid / liquid interface polymerization method mainly used in industry, the vapor / liquid interface polymerization method allows for more precise control of the polymerization process and adjustment of the membrane's structural properties. It improves solvent utilization, reduces environmental pollution, and simultaneously ensures high process efficiency and high reproducibility of results.

[0040] A polyamide thin-film composite film includes a product prepared by the method described in any one of the above-described polyamide thin-film composite films.

[0041] This invention provides a method for preparing a polyamide thin-layer composite membrane. Compared with existing technologies, the vapor / liquid interfacial polymerization method involves reacting gaseous and liquid monomers at the vapor / liquid interface. By adjusting the atomizer power, rate, pore opening size, atomization direction, and angle, the size, flow rate, concentration, and uniformity of vapor molecules during the reaction can be precisely controlled, allowing the polymerization process to be directionally regulated. This optimizes the structure and performance of the polyamide thin-layer composite membrane, improving product quality. This method is simple, requires minimal equipment, and is cost-effective. It also improves solvent utilization, reduces environmental pollution, and ensures high efficiency and high reproducibility of results. The resulting polyamide thin-layer composite membrane can be used for nanofiltration or reverse osmosis membranes depending on the desired application.

[0042] The present invention also provides a polyamide thin-film composite film, which is prepared according to the preparation method of polyamide thin-film composite film described in any of the above-mentioned methods. Compared with the prior art, the content is the same as above and will not be repeated.

[0043] The polyamide thin-film composite membrane prepared by any of the methods described above, and / or the polyamide thin-film composite membrane described above, are used in the fields of reverse osmosis and nanofiltration in water treatment. This is particularly relevant in water treatment fields such as deep purification of drinking water and municipal wastewater recycling, and more specifically, in applications such as desalination, wastewater treatment, drug separation, and food processing.

[0044] It should be noted that the following examples evaluate the membrane performance of a polyamide thin-film composite membrane preparation method: magnesium sulfate rejection rate and pure water flux. The test pressure for performance evaluation was 1 MPa, the flow rate of concentrated water and pure water was 1 L / min, the ambient temperature was 25℃, the pH value of the concentrated water was 6.5-7.5, and the concentrated water was an aqueous solution of magnesium sulfate with a concentration of 2000 ppm.

[0045] In the following embodiments, the rejection rate is defined as the difference between the conductivity of the concentrate and the product water divided by the conductivity of the concentrate; the water flux is defined as the volume of water passing through a unit area of ​​the composite separation membrane per unit time during the above test process, in L / m². 2 ·h(LMH). Each data point above is obtained by averaging six samples.

[0046] Example 1

[0047] A method for preparing a polyamide thin-film composite film includes the following steps:

[0048] A 0.33% (w / w) piperazine aqueous solution was prepared, and the membrane was immersed in it for 15 hours. During this period, a 0.3% (w / w) trimesoyl chloride (TMC) organic solution was prepared. After the membrane was removed, it was fixed on a specially designed reaction device, and the TMC solution was vaporized by microwave. The organic phase vapor entered the reaction chamber on the surface of the base membrane, and the reaction time was 120 seconds. Subsequently, it was dried at 60°C for 30 minutes.

[0049] The nanofiltration membrane prepared by this method, under the experimental conditions of a test pressure of 1 MPa, a pure water flow rate of 1.0 L / min, an ambient temperature of 25 °C, a concentrated water pH of 6.5–7.5, and a concentrated water solution of magnesium sulfate at a concentration of 2000 ppm, had a water flux of 12.78 LMH and a desalination rate of 96.0%.

[0050] Example 2

[0051] A method for preparing a polyamide thin-film composite film includes the following steps:

[0052] A 0.33% (w / w) piperazine aqueous solution was prepared, and the membrane was immersed in it for 15 hours. During this period, a 0.3% (w / w) trimesoyl chloride (TMC) organic phase solution was prepared. After the membrane was removed, it was fixed on a specially designed reaction device, and the TMC solution was vaporized by microwave. The organic phase vapor entered the reaction chamber on the surface of the base membrane, and the reaction time was 105 seconds. Subsequently, it was dried at 60°C for 30 minutes.

[0053] The nanofiltration membrane prepared by this method was tested under the following conditions: a test pressure of 1 MPa, a pure water flow rate of 1.0 L / min, an ambient temperature of 25 °C, a concentrated water pH of 6.5–7.5, and a concentrated water solution of magnesium sulfate at a concentration of 2000 ppm. The water flux was measured to be 18.18 LMH and the rejection rate was 96.8%.

[0054] Example 3

[0055] A method for preparing a polyamide thin-film composite film includes the following steps:

[0056] A 0.33% (w / w) piperazine aqueous solution was prepared, and the membrane was immersed in it for 15 hours. During this period, a 0.3% (w / w) trimesoyl chloride (TMC) organic phase solution was prepared. After the membrane was removed, it was fixed on a specially designed reaction device, and the TMC solution was vaporized by microwave. The organic phase vapor entered the reaction chamber on the surface of the base membrane, and the reaction time was 90 seconds. Subsequently, it was dried at 60°C for 30 minutes.

[0057] The nanofiltration membrane prepared by this method was tested under the following conditions: a test pressure of 1 MPa, a pure water flow rate of 1.0 L / min, an ambient temperature of 25 °C, a concentrated water pH of 6.5–7.5, and a concentrated water solution of magnesium sulfate at a concentration of 2000 ppm. The water flux was measured to be 21.2 LMH and the rejection rate was 90.3%.

[0058] Example 4

[0059] A method for preparing a polyamide thin-film composite film includes the following steps:

[0060] A 0.6% (w / w) piperazine aqueous solution was prepared, and the membrane was immersed in it for 1 hour. During this time, a 0.1% (w / w) trimesoyl chloride (TMC) organic phase solution was prepared. After the membrane was removed, it was fixed on a specially designed reaction device, and the TMC solution was vaporized by microwave. The organic phase vapor entered the reaction chamber on the surface of the base membrane, and the reaction time was 4 minutes. Subsequently, it was dried at 60°C for 30 minutes.

[0061] The nanofiltration membrane prepared by this method was tested under the following conditions: a test pressure of 1 MPa, a pure water flow rate of 1.0 L / min, an ambient temperature of 25 °C, a concentrated water pH of 6.5–7.5, and a concentrated water solution of magnesium sulfate at a concentration of 2000 ppm. The water flux was measured to be 12.9 LMH and the rejection rate was 91.3%.

[0062] Example 5

[0063] A method for preparing a polyamide thin-film composite film includes the following steps:

[0064] A 0.3% (w / w) piperazine aqueous solution was prepared, and the membrane was immersed in it for 15 hours. During this period, a 0.25% (w / w) trimesoyl chloride (TMC) organic phase solution was prepared. After the membrane was removed, it was fixed on a specially designed reaction device, and the TMC solution was vaporized by microwave. The organic phase vapor entered the reaction chamber on the surface of the base membrane, and the reaction time was 2 minutes. Subsequently, it was dried at 60°C for 30 minutes.

[0065] The nanofiltration membrane prepared by this method was tested under the following conditions: a test pressure of 1 MPa, a pure water flow rate of 1.0 L / min, an ambient temperature of 25 °C, a concentrated water pH of 6.5–7.5, and a concentrated water solution of magnesium sulfate at a concentration of 2000 ppm. The water flux was measured to be 29 LMH and the rejection rate was 82.6%.

[0066] Example 6

[0067] A method for preparing a polyamide thin-film composite film includes the following steps:

[0068] A 0.33% (w / w) piperazine aqueous solution was prepared, and the membrane was immersed in it for 12 hours. During this period, a 0.3% (w / w) trimesoyl chloride (TMC) organic phase solution was prepared. After the membrane was removed, it was fixed on a specially designed reaction device, and the TMC solution was vaporized by microwave. The organic phase vapor entered the reaction chamber on the surface of the base membrane, and the reaction time was 60 seconds. Subsequently, it was dried at 60°C for 30 minutes.

[0069] The nanofiltration membrane prepared by this method, under the experimental conditions of a test pressure of 1 MPa, a pure water flow rate of 1.0 L / min, an ambient temperature of 25 °C, a concentrated water pH of 6.5–7.5, and a concentrated water solution of magnesium sulfate at a concentration of 2000 ppm, had a water flux of 28.1 LMH and a rejection rate of 83%.

[0070] Comparative Example

[0071] Nanofiltration membranes were prepared using a traditional liquid / liquid interfacial polymerization method. The specific steps included: immersing a polysulfone-based membrane in an ethanol solution for 12 hours, followed by rinsing with deionized water. Adding a 0.6% (w / w) aqueous solution of piperazine to the membrane surface, and then filtering off the surface solution using a vacuum filtration device. Pouring a 0.1% (w / w) hexane solution of trimesoyl chloride onto the membrane surface and reacting for 40 seconds. After the reaction, the membrane was removed and heat-treated at 80°C for 30 minutes, and finally stored immersed in deionized water.

[0072] Test results show that the nanofiltration membrane prepared in this comparative example has a rejection rate of 90% for magnesium sulfate solution and a pure water flux of only 10.3 LMH / bar, which is not as good as the nanofiltration membrane prepared in any of the embodiments of Examples 1 to 6 of this invention.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a polyamide thin-film composite film, characterized in that, Includes the following steps: The base film is pretreated, and amino active groups are adsorbed on the surface of the pretreated base film. The pretreatment of the base film, wherein the surface of the pretreated base film adsorbs amino active groups, includes: immersing the base film in an aqueous solution containing amine compounds, wherein the amine compounds contained in the aqueous solution are one or more of m-phenylenediamine, p-phenylenediamine, piperazine, ethylenediamine, hexamethylenediamine, polyethyleneimine, polyaniline, and polyo-phenylenediamine. After removing the base membrane from the solution, place it below the base membrane reaction chamber; The organic phase solution containing polyacryl chloride is microwave-vaporized and then introduced into the base membrane reaction chamber. The vaporized organic phase solution and the base membrane undergo a vapor / liquid interface polymerization reaction. The organic phase solution containing polyacryl chlorides is microwave-vaporized and then introduced into the base membrane reaction chamber. The polyacryl chlorides contained in the organic phase solution are one or more of the following: pyromellitic trimethylol chloride, terephthaloyl chloride, phthaloyl chloride, pyromellitic tetramethylol chloride, adipyl chloride, and malonyl chloride. The organic phase solution containing polyacryl chloride is microwave-vaporized and then introduced into the base membrane reaction chamber. The vaporized organic phase solution and the base membrane produce a vapor / liquid interface polymerization reaction. This includes: when microwave vaporization occurs, the size, flow rate, concentration and uniformity of vapor molecules during the reaction are controlled by adjusting one or more of the following: atomizer power, rate, pore opening size, atomization direction and angle. The membrane material after the reaction is subjected to heat treatment to finally obtain a polyamide thin-film composite membrane product.

2. The method for preparing a polyamide thin-film composite film as described in claim 1, characterized in that, The amine monomer in the aqueous solution has a mass percentage of 0.05-2%.

3. The method for preparing a polyamide thin-film composite film as described in claim 1, characterized in that, The mass percentage of polyacrylamide chloride in the organic phase solution is 0.05-2%.

4. The method for preparing a polyamide thin-film composite film as described in claim 1, characterized in that, The process of heat-treating the reacted membrane material to obtain a polyamide thin-film composite membrane product includes: a heat treatment temperature of 60℃-100℃ and a time of 15-50min.

5. The method for preparing a polyamide thin-film composite film as described in claim 1, characterized in that, The base membrane is a porous microfiltration membrane or an ultrafiltration membrane.

6. A polyamide thin-film composite film, characterized in that, The polyamide thin-film composite film is prepared according to the preparation method of any one of claims 1-5.

7. The polyamide thin-film composite membrane prepared according to the method of any one of claims 1-5 is used in the fields of reverse osmosis and nanofiltration in water treatment.

Images