Preparation method of temperature-resistant polyamide composite membrane, temperature-resistant polyamide composite membrane and application

Abstract

The invention provides a preparation method of a temperature-resistant polyamide composite membrane, the temperature-resistant polyamide composite membrane and application, and relates to the technical field of temperature-resistant membrane separation. The preparation method comprises the following steps: firstly, dispersing a rigid polymer object in an auxiliary solvent, and then dispersing in an organic solvent containing multi-acyl chloride to obtain an interfacial polymerization organic phase solution; wherein the auxiliary solvent comprises an ester solvent; the preparation method comprises the following steps: mixing a polyamine monomer, an additive and water to obtain an interfacial polymerization water-phase solution; and respectively contacting a flexible porous polymer base membrane with the interfacial polymerization aqueous phase solution and the interfacial polymerization organic phase solution, carrying out polymerization reaction, and carrying out heat treatment to obtain the temperature-resistant polyamide composite membrane. The temperature-resistant polyamide composite membrane prepared by the invention has excellent high-temperature desalination performance and good long-term thermal stability, and the method has the characteristics of rapidness, convenience and easiness in large-scale application.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature-resistant membrane separation, and particularly relates to a preparation method of a temperature-resistant polyamide composite membrane, a temperature-resistant polyamide composite membrane and an application thereof. Background Art

[0002] Facing the diversification of water source environments and the complexity of application fields, the demand for membrane products suitable for high-temperature separation applications will be a key issue that cannot be avoided in the new stage of membrane material development and optimization. As the current mainstream water treatment membrane products, the working temperature of polyamide membranes is generally below 45°C. A few high-temperature resistant membrane products are only suitable for short-term high temperatures. Membrane materials for continuous high-temperature operation are prone to swelling and failure, directly leading to a decline in membrane separation performance. High-temperature water treatment requires additional cooling process flows, which will inevitably bring high energy consumption and high economic cost problems to the entire separation process.

[0003] The limited rigid structure in the polyamide molecular chain is difficult to completely restrict the high-temperature movement of molecular segments. High-temperature environments will cause irreversible structural changes such as an increase in free volume and bond breakage. Current research focuses more on designing and synthesizing new separation layers, enhancing interfacial reactions, regulating interfacial polymerization conditions, etc. However, the rigid monomers involved in the new separation layer are lacking, the selection range is narrow, and the synthesis is cumbersome and costly. It is difficult to enhance and regulate interfacial polymerization, and the water flux of the temperature-resistant membrane is not ideal. On the premise of not overly sacrificing membrane separation performance, there is still a lack of effective implementation means to improve the temperature resistance of existing polyamide membrane processes. Therefore, it is necessary to develop a temperature-resistant polyamide membrane material with good desalination performance and thermal stability.

[0004] CN113522063A discloses a nanofiltration membrane for treating printing and dyeing wastewater and a preparation method thereof; the preparation method includes: pouring an organic solution containing trimesoyl chloride and an interfacial auxiliary polymerization agent onto the surface of the membrane, reacting for 5 to 20 s, and then removing the excess solution on the surface; the interfacial auxiliary polymerization agent is selected from acetone or acetate, and the acetate is selected from any one of ethyl acetate, propyl acetate, butyl acetate, amyl acetate, heptyl acetate and n-octyl acetate. It selects two specific interfacial auxiliary polymerization agents, acetone and acetate, which reduce the interfacial tension of the organic phase and can improve the water flux to a certain extent, but the improvement of the temperature resistance effect of the membrane is not significant.

[0005] CN117679969A discloses a composite forward osmosis membrane with hydroxide ion exchange and transport function, its preparation method and application. The preparation method of the composite forward osmosis membrane includes: First, dissolve a polymer in organic solvent I to form a casting solution, and prepare a support base membrane I by the phase inversion method. Then, soak the support base membrane I in an aqueous solution and an oil-phase solution I in sequence, and an interfacial polymerization reaction occurs on the surface of the support base membrane I to form a desalination layer. The oil-phase solution I is formed by dissolving an auxiliary filler and an oil-phase monomer in organic solvent II; wherein the auxiliary filler can be a self-integrated microporous polymer or a Base polymer, etc. However, since the selected solvent contains dichloromethane and chloroform, which are good solvents for the auxiliary filler, but solvents such as dichloromethane are unfavorable to common base membranes of polysulfone and polyethersulfone, which will cause structural damage and even etching, resulting in poor bearing capacity of the base membrane.

[0006] Therefore, it is urgent to develop a polyamide composite membrane that simultaneously has excellent high-temperature desalination performance and good long-term thermal stability.

[0007] In view of this, the present invention is specifically proposed. Summary of the Invention

[0008] One of the purposes of the present invention is to provide a preparation method of a temperature-resistant polyamide composite membrane. The preparation method of the present invention has the characteristics of being fast, convenient, and easy to be applied on a large scale, showing good application potential, and the prepared polyamide composite membrane has excellent high-temperature desalination performance and good long-term thermal stability.

[0009] Another purpose of the present invention is to provide a temperature-resistant polyamide composite membrane, which is prepared by the above method and has excellent high-temperature desalination performance and good long-term thermal stability.

[0010] The third purpose of the present invention is to provide an application of the temperature-resistant polyamide composite membrane as described above in water treatment of high-salinity systems in high-temperature environments as a desalination membrane.

[0011] In order to achieve the above purposes of the present invention, the following technical solutions are specifically adopted:

[0012] In the first aspect, the present invention provides a preparation method of a temperature-resistant polyamide composite membrane, and the preparation method includes the following steps:

[0013] First, disperse a rigid polymer guest in an auxiliary solvent, and then disperse it in an organic solvent containing polyacyl chloride to obtain an interfacial polymerization organic phase solution; wherein, the auxiliary solvent includes an ester solvent;

[0014] Mix a polyamine monomer, an additive and water to obtain an interfacial polymerization aqueous phase solution;

[0015] The flexible porous polymer-based membrane is contacted with the interfacial polymerization aqueous solution and the interfacial polymerization organic solution respectively to carry out a polymerization reaction, and then heat-treated to obtain the temperature-resistant polyamide composite membrane.

[0016] Preferably, the rigid polymer guest includes a polymer with intrinsic microporosity.

[0017] Preferably, the structural formula of the polymer with intrinsic microporosity is as shown in Formula I below:

[0018]

[0019] Preferably, the weight-average molecular weight of the polymer with intrinsic microporosity is 100,000 - 300,000 Daltons.

[0020] Preferably, the auxiliary solvent is an ester solvent or a mixed solvent composed of an ester solvent and a chloroalkane solvent.

[0021] Preferably, the ester solvent includes any one of ethyl acetate, ethyl formate or ethyl silicate, preferably ethyl acetate.

[0022] Preferably, the chloroalkane solvent includes dichloromethane and / or chloroform.

[0023] Preferably, the polyfunctional acyl chloride includes any one or a combination of at least two of trimesoyl chloride, isophthaloyl chloride, phthaloyl chloride or terephthaloyl chloride.

[0024] Preferably, the organic solvent includes any one or a combination of at least two of Iaopar-G, n-hexane, cyclohexane or n-heptane.

[0025] Preferably, the interfacial polymerization organic solution includes, by mass percentage: 0.005 - 0.5% of the rigid polymer guest, 0.5 - 10% of the auxiliary solvent, 0.1 - 0.35% of the polyfunctional acyl chloride, and the balance is the organic solvent.

[0026] Preferably, the polyamine monomer includes any one or a combination of at least two of m-phenylenediamine, piperazine or p-phenylenediamine.

[0027] Preferably, the additive includes triethylamine and camphorsulfonic acid.

[0028] Preferably, the interfacial polymerization aqueous solution includes, by mass percentage: 1 - 3.5% of the polyamine monomer, 1 - 3% of triethylamine, and 2 - 5% of camphorsulfonic acid, and the balance is water.

[0029] Preferably, the material of the flexible porous polymer-based membrane includes any one or a combination of at least two of polysulfone, polyethersulfone, polyacrylonitrile, polybenzimidazole, polyaryletherketone or polyimide, preferably polysulfone and / or polyethersulfone.

[0030] Preferably, the average pore size of the flexible porous polymer-based membrane is 5-50 nm.

[0031] Preferably, the specific steps of the polymerization reaction include:

[0032] First, immerse the flexible porous polymer-based membrane in the interfacial polymerization aqueous phase solution, and after purging, then immerse it in the interfacial polymerization organic phase solution.

[0033] Preferably, the immersion time in the interfacial polymerization aqueous phase solution is 0.5-10 min.

[0034] Preferably, the immersion time in the interfacial polymerization organic phase solution is 0.5-5 min.

[0035] Preferably, the temperature of the heat treatment is 60-90 °C, and the time of the heat treatment is 1-15 min.

[0036] In a second aspect, the present invention provides a temperature-resistant polyamide composite membrane, and the temperature-resistant polyamide composite membrane is prepared by the preparation method of the temperature-resistant polyamide composite membrane as described in the first aspect.

[0037] In a third aspect, the present invention provides an application of the temperature-resistant polyamide composite membrane as described in the second aspect in water treatment of a high-salinity system in a high-temperature environment as a desalination membrane;

[0038] wherein, the high-salinity system includes seawater and / or brackish water;

[0039] wherein, the service temperature of the temperature-resistant polyamide composite membrane is 20-80 °C.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) In terms of temperature-resistant structure: The polymer with a rigid structure is introduced into the separation layer of the membrane material prepared by the present invention. The large size, rigidity and twisted structure of the polymer can be utilized to restrict the movement of polyamide molecular chains at high temperatures, making up for the poor temperature resistance caused by the insufficient rigidity of polyamide macromolecular chains; compared with the introduction of multi-dimensional nano-materials, the physical and chemical properties and structural differences between polymers are relatively small, effectively solving the interfacial defect problems caused by the increase in material expansion coefficient, crystallinity and other differences at high temperatures;

[0042] (2) In terms of desalination performance: The auxiliary dissolution solvent used in the prepared polyamide composite membrane has multiple functions. On the one hand, it can accelerate the diffusion of aqueous monomers into the organic phase, making the cross-linking of the separation layer more sufficient, thereby improving the water flux of the membrane. On the other hand, it can evenly introduce rigid polymer guests into the membrane to construct a composite temperature-resistant separation layer. Different from other single co-solvent methods, the method of the present invention can break through the drawback that the improvement of a single performance often sacrifices other performances, and realize the simultaneous improvement of the membrane permeation performance and high-temperature stability; the prepared polyamide composite membrane is applicable to high-salinity systems under high-temperature environments, and can operate continuously and stably at 70 °C for more than 30 days, with a flux decline rate of less than 10% and a desalination rate decay rate of less than 5%;

[0043] (3) In terms of membrane preparation process: Compared with methods such as interfacial polymerization regulation, separation layer modification, and post-treatment, the preparation method described in the present invention is simple and the membrane preparation route is easy to implement; the addition amount of polymer guests is small, but its effect on high-temperature resistance regulation is very prominent, and it can complete the upgrade transformation on the basis of not changing the existing mature polyamide membrane production process and operation, which is beneficial to large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0045] Figure 1 Scanning electron microscope photograph of the temperature-resistant polyamide composite membrane provided in Example 1 in the initial state.

[0046] Figure 2 Scanning electron microscope photograph of the temperature-resistant polyamide composite membrane provided in Example 1 after 30 days of operation.

[0047] Figure 3 Fourier transform infrared spectrum of the temperature-resistant polyamide composite membrane provided in Example 1.

[0048] Figure 4 High-temperature desalination performance comparison chart of the membranes prepared in Example 1, Comparative Example 1, and Comparative Example 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] Unless otherwise defined herein, scientific and technical terms used in connection with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meanings and scopes of the terms should be clear. However, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or extrinsic definition. In this application, unless otherwise specified, the use of "or" means "and / or". In addition, the use of the term "comprising" and other forms is non-restrictive.

[0050] It should be noted that specific details are set forth in the following description to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0051] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0052] In a first aspect, the present invention provides a method for preparing a temperature-resistant polyamide composite membrane, and the preparation method includes the following steps:

[0053] First, a rigid polymer guest is dispersed in an auxiliary solvent and then dispersed in an organic solvent containing polyacyl chloride to obtain an interfacial polymerization organic phase solution; wherein, the auxiliary solvent includes any one or a combination of at least two of an ester solvent, an alcohol solvent, or a ketone solvent;

[0054] A polyamine monomer, an additive, and water are mixed to obtain an interfacial polymerization aqueous phase solution;

[0055] The flexible porous polymer-based membrane is respectively contacted with the interfacial polymerization aqueous phase solution and the interfacial polymerization organic phase solution for a polymerization reaction, and then heat-treated to obtain the temperature-resistant polyamide composite membrane.

[0056] First of all, the present invention introduces a polymer with a rigid structure into the separation layer of the membrane material. The large size, rigidity, and twisted structure of the polymer can be utilized to restrict the movement of polyamide molecular segments at high temperatures, compensating for the poor temperature resistance caused by the insufficient rigidity of the polyamide polymer chain. Compared with the introduction of multi-dimensional nanomaterials (such as zeolites, titanium dioxide, graphene oxide, halloysite nanotubes, carbon nitride, and nanodiamonds, etc.), the physical and chemical properties and structural differences between polymers are relatively small, effectively solving the interfacial defect problems caused by the increased differences in the coefficient of thermal expansion, crystallinity, etc. of materials at high temperatures.

[0057] Secondly, the present invention adopts an auxiliary dissolution method to uniformly disperse a rigid polymer guest in an organic solvent containing polyacyl chloride to form an interfacial polymerization organic phase solution; in particular, the solvent used in the auxiliary dissolution is an organic solvent that is mild to polyamide and a flexible porous polymer-based membrane, that is, any one or a combination of at least two of an ester solvent, an alcohol solvent, or a ketone solvent is selected; fully considering the bearing capacity of polyamide and the flexible porous polymer-based membrane, to a great extent, avoid the problem of structural damage or even etching of the composite membrane by the solvent. First, the rigid polymer guest is dispersed in the auxiliary solvent and then dispersed in the organic solvent containing polyacyl chloride, that is, the auxiliary dissolution method is adopted, which has multiple functions. On the one hand, it can accelerate the diffusion of the aqueous phase monomer into the organic phase, making the cross-linking of the separation layer more sufficient, thereby improving the water flux of the membrane; on the other hand, it can uniformly introduce the rigid polymer guest into the membrane to construct a composite temperature-resistant separation layer.

[0058] As a preferred embodiment, the rigid polymer guest includes a polymer with intrinsic microporosity.

[0059] As a preferred embodiment, the structural formula of the polymer with intrinsic microporosity is shown as Formula I below:

[0060]

[0061] As a preferred embodiment, the weight-average molecular weight of the polymer with intrinsic microporosity is 100,000 - 300,000 Daltons, for example, it can be 100,000 Daltons, 110,000 Daltons, 120,000 Daltons, 130,000 Daltons, 140,000 Daltons, 150,000 Daltons, 160,000 Daltons, 170,000 Daltons, 180,000 Daltons, 190,000 Daltons, 200,000 Daltons, 210,000 Daltons, 220,000 Daltons, 230,000 Daltons, 240,000 Daltons, 250,000 Daltons, 260,000 Daltons, 270,000 Daltons, 280,000 Daltons, 290,000 Daltons, 300,000 Daltons, etc.

[0062] As an alternative embodiment, the auxiliary solvent is an ester solvent or a mixed solvent composed of an ester solvent and a chloroalkane solvent.

[0063] As an alternative embodiment, the ester solvent includes any one or a combination of at least two of ethyl acetate, ethyl formate, or ethyl silicate.

[0064] As a preferred embodiment, the ester solvent is ethyl acetate.

[0065] As a preferred embodiment, the mass ratio of the ester solvent to the chloroalkane solvent is 1:(0-1), for example, it can be 1:0.01, 1:0.02, 1:0.05, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, etc.

[0066] As an alternative embodiment, the polyvalent acyl chloride includes any one or a combination of at least two of trimellitic acid chloride, isophthaloyl chloride, phthaloyl chloride, or terephthaloyl chloride.

[0067] As an alternative embodiment, the organic solvent includes any one or a combination of at least two of Iaopar-G, n-hexane, cyclohexane, or n-heptane.

[0068] As an alternative embodiment, the interfacial polymerization organic phase solution includes, by mass percentage: 0.005-0.5% of the rigid polymer guest, 0.5-10% of the auxiliary solvent, 0.1-0.35% of the polyvalent acyl chloride, and the balance is the organic solvent.

[0069] As an alternative embodiment, based on the total mass of the interfacial polymerization organic phase solution being 100%, the content of the rigid polymer guest is 0.005-0.5%, for example, it can be 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.32%, 0.35%, 0.4%, 0.45%, 0.5%, etc.

[0070] As an alternative embodiment, based on the total mass of the interfacial polymerization organic phase solution being 100%, the content of the auxiliary solvent is 0.5-10%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, etc.

[0071] As an alternative embodiment, based on the total mass of the interfacial polymerization organic phase solution being 100%, the content of the polyvalent acyl chloride is 0.1-0.35%, for example, it can be 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, 0.32%, 0.34%, 0.35%, etc.

[0072] As an alternative embodiment, the polyamine monomer includes any one or a combination of at least two of m-phenylenediamine, piperazine, or p-phenylenediamine.

[0073] As an alternative embodiment, the additive includes triethylamine and camphorsulfonic acid.

[0074] As an alternative embodiment, the interfacial polymerization aqueous solution comprises, by mass percentage: 1-3.5% of polyamine monomer, 1-3% of triethylamine, and 2-5% of camphorsulfonic acid, with the balance being water.

[0075] As an alternative embodiment, based on the total mass of the interfacial polymerization aqueous solution being 100%, the content of the polyamine monomer is 1-3.5%, for example, it can be 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.5%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.5%, etc.

[0076] As an alternative embodiment, based on the total mass of the interfacial polymerization aqueous solution being 100%, the content of triethylamine is 1-3%, for example, it can be 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.5%, 2.6%, 2.8%, 3%, etc.

[0077] As an alternative embodiment, based on the total mass of the interfacial polymerization aqueous solution being 100%, the content of camphorsulfonic acid is 2-5%, for example, it can be 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, etc.

[0078] As an alternative embodiment, the material of the flexible porous polymer-based membrane includes any one or a combination of at least two of polysulfone, polyethersulfone, polyacrylonitrile, polybenzimidazole, polyaryletherketone, or polyimide.

[0079] As a preferred embodiment, the flexible porous polymer-based membrane is polysulfone and / or polyethersulfone.

[0080] As a preferred embodiment, the average pore size of the flexible porous polymer-based membrane is 5-50 nm, for example, it can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, etc.

[0081] As a preferred embodiment, the specific steps for carrying out the polymerization reaction include:

[0082] First, immerse the flexible porous polymer-based membrane in the interfacial polymerization aqueous solution. After purging, then immerse it in the interfacial polymerization organic solution.

[0083] As a preferred embodiment, the time for immersing in the interfacial polymerization aqueous solution is 0.5 - 10 min, for example, it can be 0.5 min, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, etc.

[0084] As a preferred embodiment, the time for immersing in the interfacial polymerization organic solution is 0.5 - 5 min, for example, it can be 0.5 min, 1 min, 2 min, 3 min, 4 min, 5 min, etc.

[0085] As an alternative embodiment, the temperature of the heat treatment is 60 - 90 °C, for example, it can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, etc., and the time of the heat treatment is 1 - 15 min, for example, it can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, etc.

[0086] In a second aspect, the present invention provides a temperature-resistant polyamide composite membrane, and the temperature-resistant polyamide composite membrane is prepared by the preparation method of the temperature-resistant polyamide composite membrane as described in the first aspect.

[0087] In a third aspect, the present invention provides an application of the temperature-resistant polyamide composite membrane as described in the second aspect in water treatment of high-salinity systems in high-temperature environments as a desalination membrane.

[0088] As an alternative embodiment, the high-salinity system includes seawater and / or brackish water.

[0089] As an alternative embodiment, the service temperature of the temperature-resistant polyamide composite membrane is 20 - 80 °C, for example, it can be 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, etc.

[0090] The present invention will be further described below through examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0091] Preparation Example 1

[0092] This preparation example provides a self-microporous polymer, and the structural formula of the self-microporous polymer is shown as Formula I below:

[0093]

[0094] Among them, the weight-average molecular weight of the self-microporous polymer is 200,000 Daltons.

[0095] The self-microporous polymer provided by this preparation example is prepared by the following steps:

[0096] 5,5',6,6'-Tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane (TTSBI) (10 g, 0.029 mol), tetrafluoroterephthalonitrile (TFTPN) (6 g, 0.029 mol) and potassium carbonate (10.5 g, 0.075 mol) were uniformly dispersed in 200 mL of N,N-dimethylformamide (DMF) to obtain a mixture; under nitrogen protection, the above mixture was heated to 65 °C and maintained for 72 h for reaction; after the reaction was completed, the reaction solution was restored to room temperature, an excessive amount of anhydrous methanol was added, and after precipitation, it was washed 3 times with anhydrous methanol and then stirred in an aqueous solution of 0.1 wt% hydrochloric acid for 12 h to finally obtain the self-microporous polymer.

[0097] Example 1

[0098] This example provides a temperature-resistant polyamide composite membrane, which is prepared by the following steps:

[0099] 0.10 g of the self-microporous polymer provided in Preparation Example 1 with a weight-average molecular weight of 120,000 Daltons was uniformly dispersed in 49.90 g of ethyl acetate to obtain a polymer / ethyl acetate solution; subsequently, 5.00 g of the polymer / ethyl acetate solution and 0.19 g of trimesoyl chloride were weighed and dispersed in 95.00 g of Iaopar-G solution to prepare an interfacial polymerization organic phase solution;

[0100] At room temperature, 4.50 g of m-phenylenediamine, 5.65 g of camphorsulfonic acid, and 2.35 g of triethylamine were dispersed in 137.50 g of deionized water to prepare an interfacial polymerization aqueous phase solution;

[0101] At room temperature, a flexible porous polysulfone substrate membrane (average pore size of 30 nm) was fully immersed in the above interfacial polymerization aqueous phase solution (immersion time was 2 min), taken out and the surface was purged with nitrogen to remove the excess amine monomers on the surface; then it was immersed in the above interfacial polymerization organic phase solution (immersion time was 1 min) to complete the interfacial polymerization reaction; finally, it was taken out and heat-treated at 80 °C for 5 min to obtain the temperature-resistant polyamide composite membrane (P-PA Membrane).

[0102] Microtopography characterization: Figure 1Scanning electron microscope photograph of the temperature-resistant polyamide composite membrane provided for Example 1 in its initial state. Figure 2 Scanning electron microscope photograph of the temperature-resistant polyamide composite membrane provided for Example 1 after 30 days of operation. From the comparison between Figure 1 and Figure 2 it can be seen that the temperature-resistant polyamide composite membrane prepared by the method of the present invention still maintains the dense and rough structure of the polyamide membrane after continuously operating for 30 days in a high-temperature environment of 70 °C, and the microtopography of the membrane material has not changed significantly.

[0103] Chemical composition characterization: Figure 3 is the Fourier transform infrared spectrum of the temperature-resistant polyamide composite membrane in Example 1. The characteristic peaks of polyamide still exist after continuously operating for 30 days in a high-temperature environment of 70 °C, such as around 1665 cm -1 (carbonyl stretching vibration), around 1540 cm -1 (N-H bending vibration and C-N stretching vibration), and around 3300 cm -1 (N-H stretching vibration), etc., and their positions and intensities have not changed significantly.

[0104] Example 2

[0105] This example provides a temperature-resistant polyamide composite membrane, which is different from Example 1 in that: for the interfacial polymerization organic phase solution ratio, the addition amount of the polymer / ethyl acetate solution is 1.00 g, the addition amount of trimesoyl chloride is 0.19 g, and the addition amount of Iaopar-G solution is 99.00 g. Other steps are the same as those in Example 1.

[0106] Example 3

[0107] This example provides a temperature-resistant polyamide composite membrane, which is different from Example 1 in that: the addition amount of the polymer / ethyl acetate solution is 3.00 g, the addition amount of trimesoyl chloride is 0.19 g, and the addition amount of Iaopar-G solution is 97.00 g. Other steps are the same as those in Example 1.

[0108] Example 4

[0109] This example provides a temperature-resistant polyamide composite membrane, which is different from Example 1 in that: the addition amount of the polymer / ethyl acetate solution is 8.00 g, the addition amount of trimesoyl chloride is 0.19 g, and the addition amount of Iaopar-G solution is 92.00 g. Other steps are the same as those in Example 1.

[0110] Example 5

[0111] This example provides a temperature-resistant polyamide composite membrane, which is different from Example 1 in that: the addition amount of the polymer / ethyl acetate solution is 5.00 g, the addition amount of trimellitic acid chloride is 0.15 g, and the addition amount of Iaopar-G solution is 95.00 g. Other steps are the same as those in Example 1.

[0112] Example 6

[0113] This example provides a temperature-resistant polyamide composite membrane, which is different from Example 1 in that: ethyl acetate is replaced with a mixed solution of dichloromethane and ethyl acetate of equal mass (where the volume ratio of dichloromethane to ethyl acetate is 0.5:1), and the contact time of the organic phase is 30 s. Other steps are the same as those in Example 1.

[0114] Example 7

[0115] This example provides a temperature-resistant polyamide composite membrane, which is different from Example 1 in that: ethyl acetate is replaced with a mixed solution of chloroform and ethyl acetate of equal mass (where the volume ratio of chloroform to ethyl acetate is 0.5:1), and the contact time of the organic phase is 30 s. Other steps are the same as those in Example 1.

[0116] Comparative Example 1

[0117] This comparative example provides a polyamide composite membrane, which is different from Example 1 in that: the self-microporous polymer provided in Preparation Example 1 is not added. Other steps are the same as those in Example 1.

[0118] Comparative Example 2

[0119] This comparative example provides a polyamide composite membrane, which is different from Example 1 in that: the self-microporous polymer provided in Preparation Example 1 is not added, and ethyl acetate is no longer added. Other steps are the same as those in Example 1.

[0120] Comparative Example 3

[0121] This comparative example provides a polyamide composite membrane, which is different from Example 1 in that: ethyl acetate is not added. Other steps are the same as those in Example 1.

[0122] Comparative Example 4

[0123] This comparative example provides a polyamide composite membrane, which is different from Example 1 in that: ethyl acetate is replaced with an equal mass of dichloromethane. Other steps are the same as those in Example 1.

[0124] Due to the strong etching effect of dichloromethane on the polysulfone membrane, obvious polysulfone dissolution occurs during the preparation process, and at this time the membrane loses its high desalination ability.

[0125] Comparative Example 5

[0126] This comparative example provides a polyamide composite membrane, which is different from Example 1 in that ethyl acetate is replaced with an equal mass of chloroform, and other steps are the same as those in Example 1.

[0127] Due to the strong etching effect of chloroform on the polysulfone membrane, obvious polysulfone dissolution phenomenon occurred during the preparation process, and at this time the membrane lost its high desalination ability.

[0128] Test Example 1

[0129] Test samples: the temperature-resistant polyamide composite membranes provided in Examples 1-7 and the polyamide composite membranes provided in Comparative Examples 1-3.

[0130] Test method: The desalination rate and permeation flux of the membrane were measured by a cross-flow nanofiltration performance test device, and the working pressure was set at 5.6 MPa and the sodium chloride aqueous solution system was 32 g / L.

[0131] The test results are as shown in Table 1 below and Figure 4 as shown (" / " represents that this test was not carried out):

[0132] Table 1

[0133]

[0134] From Table 1 and Figure 4 the results, it can be seen that the temperature-resistant polyamide composite membrane (P-PA Membrane) prepared by the present invention exhibits excellent high-temperature stability. It can still maintain good desalination ability after stable operation at 70 °C for 30 days. Its water flux decline rate is less than 10%, and the desalination rate attenuation rate is lower than 5%. However, the polyamide membrane prepared with pure ethyl acetate (E-PA Membrane) and the polyamide membrane prepared by the traditional method (PA Membrane) both show an obvious downward trend in performance during long-term operation. This phenomenon benefits from the excellent temperature-resistant composite active layer. On the one hand, the rigid polymer restricts the high-temperature movement of polyamide molecular chains, reduces the change in free volume, and increases its thermal stability; on the other hand, the use of ethyl acetate not only facilitates the uniform introduction of polymer guests but also regulates interfacial polymerization to achieve the purpose of improving the water flux of the membrane. Above all, it proves that the temperature-resistant polyamide composite separation membrane in the present invention has good desalination performance and excellent high-temperature stability performance.

[0135] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a temperature-resistant polyamide composite film, characterized in that, The preparation method comprises the following steps: First, disperse the rigid polymer guest in an auxiliary solvent and then in an organic solvent containing polyacyl chloride to obtain an interfacial polymerization organic phase solution; wherein, the auxiliary solvent includes an ester solvent; Mix a polyamine monomer, an additive and water to obtain an interfacial polymerization aqueous phase solution; Contact the flexible porous polymer base film with the interfacial polymerization aqueous phase solution and the interfacial polymerization organic phase solution respectively to carry out a polymerization reaction, and then perform heat treatment to obtain the temperature-resistant polyamide composite film.

2. The preparation method of the temperature-resistant polyamide composite film according to claim 1, characterized in that, The rigid polymer guest includes a polymer with intrinsic microporosity; Preferably, the structural formula of the polymer with intrinsic microporosity is as shown in Formula I below: Preferably, the weight-average molecular weight of the polymer with intrinsic microporosity is 100,000 - 300,000 Daltons.

3. The preparation method of the temperature-resistant polyamide composite film according to claim 1, characterized in that, The auxiliary solvent is an ester solvent or a mixed solvent composed of an ester solvent and a chloroalkane solvent; Preferably, the ester solvent includes any one of ethyl acetate, ethyl formate or ethyl silicate, and preferably ethyl acetate; Preferably, the chloroalkane solvent includes dichloromethane and / or chloroform; Preferably, the mass ratio of the ester solvent to the chloroalkane solvent is 1:(0 - 1).

4. The preparation method of the temperature-resistant polyamide composite film according to claim 1, characterized in that The polyacyl chloride includes any one or a combination of at least two of trimesoyl chloride, isophthaloyl chloride, phthaloyl chloride or terephthaloyl chloride; Preferably, the organic solvent includes any one or a combination of at least two of Iaopar-G, n-hexane, cyclohexane or n-heptane; Preferably, the interfacial polymerization organic phase solution comprises, by mass percentage: 0.005 - 0.5% of the rigid polymer guest, 0.5 - 10% of the auxiliary solvent, 0.1 - 0.35% of the polyacyl chloride, and the balance is the organic solvent.

5. The preparation method of the temperature-resistant polyamide composite film according to claim 1, characterized in that, The polyamine monomer includes any one or a combination of at least two of m-phenylenediamine, piperazine or p-phenylenediamine; Preferably, the additive includes triethylamine and camphorsulfonic acid; Preferably, the interfacial polymerization aqueous phase solution comprises, by mass percentage: 1 - 3.5% of the polyamine monomer, 1 - 3% of triethylamine and 2 - 5% of camphorsulfonic acid, and the balance is water.

6. The preparation method of the temperature-resistant polyamide composite film according to claim 1, characterized in that, The material of the flexible porous polymer base film includes any one or a combination of at least two of polysulfone, polyethersulfone, polyacrylonitrile, polybenzimidazole, polyaryletherketone or polyimide, and preferably polysulfone and / or polyethersulfone; Preferably, the average pore size of the flexible porous polymer base film is 5 - 50 nm.

7. The preparation method of the temperature-resistant polyamide composite film according to claim 1, characterized in that, The specific steps for carrying out the polymerization reaction include: First, immerse the flexible porous polymer base film in the interfacial polymerization aqueous phase solution, and after purging, then immerse it in the interfacial polymerization organic phase solution; Preferably, the immersion time in the interfacial polymerization aqueous phase solution is 0.5 - 10 min; Preferably, the immersion time in the interfacial polymerization organic phase solution is 0.5 - 5 min.

8. The preparation method of the temperature-resistant polyamide composite film according to claim 1, characterized in that, The temperature of the heat treatment is 60 - 90 °C, and the time of the heat treatment is 1 - 15 min.

9. A temperature-resistant polyamide composite film, characterized in that, The temperature-resistant polyamide composite film is prepared by the preparation method of the temperature-resistant polyamide composite film according to any one of claims 1 - 8.

10. Use of the temperature-resistant polyamide composite membrane according to claim 9 in water treatment of a high-salinity system in a high-temperature environment as a desalination membrane; Among them, The high-salinity system includes seawater and / or brackish water; Wherein, the service temperature of the temperature-resistant polyamide composite membrane is 20 to 80 °C.

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