CN113893711A - High-flux reverse osmosis composite membrane and preparation method thereof - Google Patents
High-flux reverse osmosis composite membrane and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a preparation method of a high-flux reverse osmosis composite membrane, which comprises the steps of adopting m-phenylenediamine, imidazole and derivatives thereof as an aqueous solution of interfacial polymerization, limiting an imidazole additive to be an imidazole compound containing secondary amine groups, carrying out interfacial polymerization reaction on the m-phenylenediamine, the imidazole additive and trimesoyl chloride on a porous base membrane to form a polyamide separation layer, carrying out heat treatment on the obtained porous base membrane with the polyamide separation layer at the temperature of 50-80 ℃ for 2-30 min, and then soaking in deionized water to obtain the high-flux reverse osmosis composite membrane. The secondary amine functional group in the imidazole ring of the imidazole additive can react with acyl chloride to form imidazole amide, so that the imidazole additive and m-phenylenediamine can compete in the interfacial polymerization process to consume a part of acyl chloride groups, and the competitive reaction of molecular scale can uniformly reduce the crosslinking degree of a polyamide material, so that the formed reverse osmosis composite membrane has remarkably improved water flux.
Description
Technical Field
The invention relates to the technical field of reverse osmosis membrane preparation, in particular to a high-flux reverse osmosis composite membrane and a preparation method thereof.
Background
Reverse osmosis is considered as a key technology for solving the problems of water pollution and water purification resource shortage, is widely applied to the fields of deep water treatment such as zero emission and recycling of industrial wastewater, seawater/brackish water desalination and the like, and becomes an important guarantee for harmonious development of human beings and nature. The core of the reverse osmosis technology lies in the reverse osmosis membrane, which is mainly of a composite membrane structure in the current market and consists of an upper compact separation layer and a lower porous support layer, and the separation performance of the membrane is mainly determined by the upper separation layer. The separation layer of the reverse osmosis composite membrane is mainly prepared by interfacial polymerization reaction between a water phase solution containing m-phenylenediamine (MPD) and an oil phase solution containing m-benzenetricarboxychloride (TMC), and the formed membrane material is cross-linked wholly aromatic polyamide.
The continuous improvement of the water flux of the membrane while maintaining the rejection of the reverse osmosis membrane is a difficult point in the field of membrane research and is a continuously pursued target for the development and application of membrane technology, because the improvement of the membrane flux also means lower operation energy consumption and equipment investment. At present, means for improving flux of a reverse osmosis composite membrane mainly comprise designing a novel membrane forming monomer, introducing an interfacial polymerization additive, optimizing a membrane preparation method, post-treatment of the composite membrane and the like, wherein the introduction of the additive can obviously influence diffusion rate of the monomer, solubility of the monomer, miscibility of a water phase and an organic phase and the like, and further regulates and controls interfacial polymerization process and separation performance of the composite membrane, and has the advantages of low cost, simple process, obvious effect and the like. The additives currently used can be broadly classified into acids and bases, surfactants, organic solvents, co-solvents, inorganic salts, and the like. For example, the addition of dimethyl sulfoxide can increase the miscibility of the aqueous phase and the organic phase, facilitate the diffusion of the amine monomer from the aqueous phase to the organic phase, form a rougher membrane surface, increase the effective area of the membrane, and further endow the membrane with higher permeation flux. In addition, insoluble nanomaterials have also received much attention as composite film additives. If carbon nanotubes, graphene, metal-organic framework materials and the like are added in the interfacial polymerization process, a large number of inorganic-organic interfaces are formed, so that an additional channel is provided for water molecule diffusion, but the nucleophilicity of the nano additive and the main material is poor, the membrane permeation flux is improved, and the interception of the membrane is reduced.
The cross-linked polyamide separation layer contains sub-nanometer level grid pores and gathering pores, which are the free volume cavities between the polyamide molecular chains and the gaps between the polyamide aggregates. The existence of the sub-nanometer pore canal provides a diffusion channel for transmembrane mass transfer of water molecules, so that the number and the size of micropores are important factors influencing transmembrane mass transfer resistance of the water molecules. If the crosslinking degree of the polyamide is controllably reduced on the premise of not damaging the crosslinking main body structure, and a large number of uniformly distributed intermolecular micropores are manufactured on the molecular scale, the permeation flux of the membrane can be greatly improved, and the interception performance of the membrane is prevented from being greatly reduced. However, due to the fast reaction rate between monomers in the interfacial polymerization, the nano-scale reaction region, and the complex and unclear film-forming process, the controllable adjustment of the degree of crosslinking and the microporous properties of the polyamide film material is still difficult.
Disclosure of Invention
In order to solve the problems, the invention provides a high-flux reverse osmosis composite membrane and a preparation method thereof.
In order to achieve the purpose, the invention specifically adopts the following technical scheme:
a preparation method of a high-flux reverse osmosis composite membrane comprises the following steps:
(1) dissolving m-phenylenediamine and an imidazole additive in water, and fully stirring to obtain an aqueous phase solution;
(2) soaking the porous base membrane in the aqueous phase solution prepared in the step (1) for 1-5 min, taking out, and drying the residual aqueous phase solution on the surface of the porous base membrane by air knife drying or roller drying;
(3) dissolving trimesoyl chloride in an organic solvent and fully stirring to obtain a trimesoyl chloride oil phase solution;
(4) slowly pouring the trimesoyl chloride oil phase solution prepared in the step (3) onto the upper surface of the membrane obtained in the step (2), carrying out interfacial polymerization reaction for 10-120 s to form a cross-linked polyamide separation layer, and pouring the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (4) at 50-80 ℃ for 2-30 min, and then soaking in deionized water to obtain the polyamide reverse osmosis composite membrane.
Further, the imidazole additive in the step (1) is an imidazole compound containing a secondary amine group.
Further, in the step (1), the imidazole additive is at least one of imidazole, 2-methylimidazole, 3-methylimidazole, 4-methylimidazole, 2, 4-dimethylimidazole, 4- (hydroxymethyl) imidazole, 2-ethyl-4-methylimidazole and histamine.
Furthermore, in the step (1), the mass concentration of the m-phenylenediamine is 0.1-5%, and the mass concentration of the imidazole additive is 0.1-5%.
Further, the porous base membrane in the step (2) is one of a polysulfone ultrafiltration membrane, a polyether sulfone ultrafiltration membrane, a polyimide ultrafiltration membrane, a polyacrylonitrile ultrafiltration membrane, a polyethylene ultrafiltration membrane or a polypropylene ultrafiltration membrane.
Further, the organic solvent in the step (3) is at least one of hexane, cyclohexane, n-heptane, toluene, xylene, isopar G, isopar E, isopar H, isopar L or isopar M.
Further, the mass concentration of the trimesoyl chloride oil phase solution in the step (3) is 0.01-2%.
Further, the soaking time in the deionized water in the step (5) is 10-60 min.
Imidazole and derivatives thereof are used as water phase additives of interfacial polymerization, the imidazole additives are limited to imidazole compounds containing secondary amine groups, secondary amine functional groups in imidazole rings can react with acyl chloride to form imidazole amide (or N-acyl imidazole), so that the imidazole additives and m-phenylenediamine can form competition in the interfacial polymerization process and consume a part of acyl chloride groups, and the competition reaction of molecular scale can uniformly reduce the crosslinking degree of polyamide materials; in addition, imidazole amide formed by reaction can be hydrolyzed in the process of membrane soaking to enable imidazole groups to leave, and due to the fact that a cross-linked framework of a separation layer is formed, imidazole occupies a certain spatial position, more intermolecular chain micropores are further generated due to the imidazole leaving, a large number of carboxyl groups can be formed due to hydrolysis, the hydrophilicity of membrane materials is increased, the transmembrane mass transfer resistance of water molecules is reduced due to multiple effects, and the formed reverse osmosis composite membrane has remarkably improved water flux. Taking 2-methylimidazole as an example, the reaction process and hydrolysis process of the mixed aqueous phase solution of m-phenylenediamine and 2-methylimidazole and the trimesoyl chloride oil phase solution are as follows:
the invention has the following beneficial effects:
(1) imidazole and derivatives (2-methylimidazole, histamine and the like) thereof are used as a space occupying agent, imidazole is introduced into the interfacial polymerization preparation process of the reverse osmosis membrane in the form of an additive, the crosslinking degree of the polyamide membrane is controllably reduced by utilizing the special properties of imidazole and N-acyl imidazole, more sub-nanometer micropores are created in the membrane material from the molecular scale, and the N-acyl imidazole is easily hydrolyzed in water and forms a large number of carboxyl groups, so that the hydrophilicity of the membrane material is increased, the water production flux of the membrane is remarkably improved, and the high interception performance of the reverse osmosis membrane is ensured;
(2) the reverse osmosis composite membrane provided by the invention has the advantages of simple preparation process, controllable operation and low cost, and the flux of the prepared reverse osmosis composite membrane can reach 59.2 L.m-2·h-1·MPa-1The interception of sodium chloride is maintained to be more than 98.5 percent, and the method can be used for water treatment processes such as seawater desalination, brackish water desalination, industrial wastewater treatment and the like, and has wide industrial application prospect.
Drawings
The invention will be further described with reference to the accompanying drawings in which:
FIG. 1 is a surface electron microscope image of a reverse osmosis composite membrane prepared in comparative example 1
FIG. 2 is a surface electron microscope image of the reverse osmosis composite membrane prepared in examples 1 to 4;
FIG. 3 is a surface X-ray photoelectron spectroscopy (XPS) chart of the reverse osmosis composite membrane prepared in comparative example 1 and examples 1 to 4;
FIG. 4 is a high-resolution XPS peak plot of oxygen on the surface of the reverse osmosis composite membrane prepared in comparative example 1;
FIG. 5 is a high resolution XPS peak plot of oxygen on the surface of the reverse osmosis composite membranes prepared in examples 1-4.
Detailed Description
In order to make the advantages and technical solutions of the present invention clearer and clearer, the present invention is described in detail below with reference to specific embodiments and accompanying drawings.
The raw materials required by the invention can be purchased from commercial sources.
In the following examples and comparative examples, the reverse osmosis composite membranes prepared were tested, specifically, after pre-pressing for 1 hour under the conditions of 1.0MPa, 25 ℃ and 7LPM, the rejection rate of 2000mg/L sodium chloride and the water production flux thereof were tested, and the water production flux unit LMH of the composite membrane was L.m-2·h-1·MPa-1。
Comparative example 1
The comparative example 1 provides a preparation method of a reverse osmosis composite membrane, comprising the following steps:
(1) dissolving m-phenylenediamine in water to obtain a water phase solution, wherein the mass concentration is 2%;
(2) soaking the polysulfone ultrafiltration membrane in the aqueous phase solution prepared in the step (1) for 5min, taking out, and drying the residual aqueous solution on the surface of the membrane by an air knife;
(3) dissolving trimesoyl chloride in normal hexane to obtain 0.1% by mass of trimesoyl chloride oil phase solution;
(4) slowly pouring the oil phase solution obtained in the step (3) onto the upper surface of the membrane obtained in the step (2), initiating an interfacial polymerization reaction, continuing for 60s to form a cross-linked polyamide separation layer, and pouring out the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (4) at 60 ℃ for 2 minutes, and then soaking the membrane in deionized water for 30 minutes to obtain the polyamide reverse osmosis composite membrane.
The polyamide reverse osmosis composite membrane prepared by the method is tested for separation performance, the water production flux is 11.4LMH, and the sodium chloride rejection rate is 98.9%.
Comparative example 2
Comparative example 2 a reverse osmosis composite membrane was prepared using 1-methylimidazole containing no secondary amine group in the imidazole ring as an additive, wherein the molecular formula of 1-methylimidazole is shown as follows:
the comparative example 2 provides a preparation method of a reverse osmosis composite membrane, which comprises the following steps:
(1) dissolving m-phenylenediamine and 1-methylimidazole in water to obtain an aqueous phase solution, wherein the mass concentration of the m-phenylenediamine is 2%, and the mass concentration of the 1-methylimidazole is 1% and 2% respectively;
(2) respectively soaking the polysulfone ultrafiltration membranes in the aqueous phase solution prepared in the step (1) for 5min, taking out, and drying the residual aqueous solution on the surfaces of the membranes by an air knife;
(3) dissolving trimesoyl chloride in normal hexane to obtain 0.1% by mass of trimesoyl chloride oil phase solution;
(4) slowly pouring the oil phase solution obtained in the step (3) onto the upper surface of the membrane obtained in the step (2) respectively, initiating an interfacial polymerization reaction, lasting for 60s to form a cross-linked polyamide separation layer, and pouring the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (4) at 60 ℃ for 2 minutes, and then soaking the membrane in deionized water for 30 minutes to obtain a series of polyamide reverse osmosis composite membranes.
The reverse osmosis composite membrane prepared by the method is tested for separation performance, the water flux of the reverse osmosis membrane prepared by adding 1% of 1-methylimidazole is 0.53LMH, the sodium chloride rejection rate is 97.6%, the water flux of the reverse osmosis membrane prepared by adding 2% of 1-methylimidazole is 0.69LMH, and the sodium chloride rejection rate is 97.2%. Through analysis, the hydrogen atom of secondary amine in the imidazole ring of the 1-methylimidazole is replaced by methyl, and the secondary amine cannot perform nucleophilic substitution reaction with acyl chloride any longer, so that imidazole amide cannot be formed, in addition, the detection result also shows that the addition of the 1-methylimidazole reduces the water production flux and the salt retention performance of the reverse osmosis membrane, and the existence of the 1-methylimidazole influences the reaction of the m-phenylenediamine and the trimesoyl chloride and influences the microporous structure of the formed polyamide layer.
Example 1
This example 1 provides a method for preparing a high-flux reverse osmosis composite membrane, including the following steps:
(1) dissolving m-phenylenediamine and 2-methylimidazole in water to obtain an aqueous phase solution, wherein the mass concentration of the m-phenylenediamine is 2%, and the mass concentration of the 2-methylimidazole is 0.5%, 1%, 2%, 3%, 4% and 5% respectively;
(2) respectively soaking the polysulfone ultrafiltration membranes in the aqueous phase solution prepared in the step (1) for 5min, taking out, and drying the residual aqueous solution on the surfaces of the membranes by an air knife;
(3) dissolving trimesoyl chloride in normal hexane to obtain 0.1% by mass of trimesoyl chloride oil phase solution;
(4) slowly pouring the oil phase solution obtained in the step (3) onto the upper surface of the membrane obtained in the step (2) respectively, initiating an interfacial polymerization reaction, lasting for 60s to form a cross-linked polyamide separation layer, and pouring the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (4) at 60 ℃ for 2 minutes, and then soaking the membrane in deionized water for 30 minutes to obtain a series of polyamide reverse osmosis composite membranes.
A series of reverse osmosis composite membranes prepared by the above method were subjected to separation performance tests, and the mass concentrations of 2-methylimidazole, i.e., 0.5%, 1%, 2%, 3%, 4%, and 5%, were recorded as examples 1-1 to 1-6, respectively, and the test results are shown in table 1.
Table 1 results of separation performance test of example 1 and comparative example 1
| Name (R) | 2-methylimidazole concentration (%) | Water production flux LMH | Sodium chloride rejection (%) |
| Comparative example 1 | 0 | 11.4 | 98.9 |
| Examples 1 to 1 | 0.5 | 15.4 | 99.1 |
| Examples 1 to 2 | 1.0 | 31.0 | 98.8 |
| Examples 1 to 3 | 2.0 | 42.6 | 98.8 |
| Examples 1 to 4 | 3.0 | 59.2 | 98.7 |
| Examples 1 to 5 | 4.0 | 67.7 | 97.7 |
| Examples 1 to 6 | 5.0 | 82.9 | 95.9 |
From the detection results of the example 1 and the comparative example 1 in the table 1, the water production flux of the reverse osmosis composite membrane prepared by adding 2-methylimidazole into the aqueous phase solution is remarkably improved, and the water production flux of the reverse osmosis composite membrane continuously increases with the increase of the addition amount of 2-methylimidazole; for the salt rejection performance, when the addition amount of the 2-methylimidazole is not more than 3%, the rejection rate of the reverse osmosis membrane on sodium chloride is maintained to be more than 98.5%, and when the addition amount of the 2-methylimidazole is more than 3%, the rejection rate of the sodium chloride is reduced to some extent, and the phenomena of loose reverse osmosis or low-pressure reverse osmosis occur.
In addition, we also performed electron microscope examination on the reverse osmosis composite membranes prepared in comparative example 1 and examples 1-4, as shown in fig. 1 and fig. 2, (a) and (b) in fig. 1 are electron microscope images of the membrane surface of the reverse osmosis composite membrane prepared in comparative example 1 under different magnifications, and (a) and (b) in fig. 2 are electron microscope images of the membrane surface of the reverse osmosis composite membrane prepared in examples 1-4 under different magnifications, and as can be seen from comparing fig. 1 and fig. 2, the membrane surface obtained after adding 2-methylimidazole has a rough ring structure, which is beneficial to increasing the effective mass transfer area of the membrane.
As shown in fig. 3, which is an X-ray photoelectron spectroscopy (XPS) graph of the membrane surface of comparative example 1 and examples 1 to 4, it can be seen from fig. 3 that the ratio of oxygen atoms to nitrogen atoms of the reverse osmosis composite membrane obtained by adding 2-methylimidazole is increased, the degree of crosslinking of the polyamide separation layer of the surface composite membrane is decreased, the composite membrane becomes relatively loose, the number of water molecule diffusion channels is increased, and the water production flux is increased.
As shown in fig. 4 and 5, the high-resolution XPS peak profiles of the oxygen element on the surfaces of the reverse osmosis composite membranes obtained in comparative example 1 and examples 1 to 4 are shown, respectively. Fig. 4 and 5 further show that the addition of 2-methylimidazole increases the content of carboxyl groups contained in the separation layer of the composite membrane, which can increase the hydrophilicity of the membrane material and also contribute to the increase of the water flux.
Example 2
This example 2 provides a method for preparing a high-flux reverse osmosis composite membrane, including the following steps:
(1) dissolving m-phenylenediamine and imidazole in water to obtain an aqueous phase solution, wherein the mass concentration of the m-phenylenediamine is 2%, and the mass concentration of the imidazole is 1.5%;
(2) soaking the polyethersulfone ultrafiltration membrane in the aqueous phase solution prepared in the step (1) for 5min, taking out, and drying the residual aqueous solution on the surface of the membrane by an air knife;
(3) dissolving trimesoyl chloride in cyclohexane to obtain a trimesoyl chloride oil phase solution with the mass fraction of 0.15%;
(4) slowly pouring the oil phase solution obtained in the step (3) onto the upper surface of the membrane obtained in the step (1), initiating an interfacial polymerization reaction, continuing for 30s to form a cross-linked polyamide separation layer, and pouring out the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (4) at 60 ℃ for 5 minutes, and then soaking the membrane in deionized water for 30 minutes to obtain the polyamide reverse osmosis composite membrane.
The reverse osmosis composite membrane prepared by the method is tested for separation performance, the water production flux is 39.2LMH, and the sodium chloride rejection rate is 98.8%.
Example 3
This example 3 provides a method for preparing a high-flux reverse osmosis composite membrane, including the following steps:
(1) dissolving m-phenylenediamine and 3-methylimidazole in water to obtain an aqueous phase solution, wherein the mass concentration of the m-phenylenediamine is 5%, and the mass concentration of the imidazole is 2.5%;
(2) soaking the polysulfone ultrafiltration membrane in the aqueous phase solution prepared in the step (1) for 1min, taking out, and drying the residual aqueous solution on the surface of the membrane by a roller;
(3) dissolving trimesoyl chloride in cyclohexane to obtain an oil phase solution with the mass fraction of 2.0%;
(4) slowly pouring the oil phase solution obtained in the step (3) onto the upper surface of the membrane obtained in the step (1), initiating an interfacial polymerization reaction, lasting for 10s to form a cross-linked polyamide separation layer, and pouring out the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (4) at 80 ℃ for 2 minutes, and then soaking the membrane in deionized water for 30 minutes to obtain the polyamide reverse osmosis composite membrane.
The reverse osmosis composite membrane prepared by the method is tested for separation performance, the water production flux is 26.9LMH, and the sodium chloride rejection rate is 99.2%.
Example 4
This embodiment 4 provides a method for preparing a high-flux reverse osmosis composite membrane, including the following steps:
(1) dissolving m-phenylenediamine and 2, 4-dimethylimidazole in water to obtain an aqueous phase solution, wherein the mass concentration of the m-phenylenediamine is 2.0%, and the mass concentration of the imidazole is 3.0%;
(2) soaking polysulfone in the aqueous phase solution prepared in the step (1) for 5min, taking out, and drying the residual aqueous solution on the surface of the membrane by a roller;
(3) dissolving trimesoyl chloride in isopar G to obtain an oil phase solution with the mass fraction of 0.2%;
(4) slowly pouring the oil phase solution obtained in the step (3) onto the upper surface of the membrane obtained in the step (1), initiating an interfacial polymerization reaction, continuing for 60s to form a cross-linked polyamide separation layer, and pouring out the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (5) at 60 ℃ for 2 minutes, and then soaking the membrane in deionized water for 30 minutes to obtain the polyamide reverse osmosis composite membrane.
The reverse osmosis composite membrane prepared by the method is tested for separation performance, the water production flux is 37.5LMH, and the sodium chloride rejection rate is 98.7%.
Example 5
This example 5 provides a method for preparing a high-flux reverse osmosis composite membrane, including the following steps:
(1) dissolving m-phenylenediamine and histamine in water to obtain an aqueous phase solution, wherein the mass concentration of the m-phenylenediamine is 0.1%, and the mass concentration of imidazole is 0.1%;
(2) ultra-filtering polyether sulfone and soaking in the aqueous phase solution prepared in the step (1) for 5min, taking out, and drying the residual aqueous solution on the surface of the membrane by a roller;
(3) dissolving trimesoyl chloride in n-hexane to obtain an oil phase solution with the mass fraction of 0.01%;
(4) slowly pouring the oil phase solution obtained in the step (3) onto the upper surface of the membrane obtained in the step (1), initiating an interfacial polymerization reaction, continuing for 120s to form a cross-linked polyamide separation layer, and pouring out the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (4) at 50 ℃ for 30 minutes, and then soaking the membrane in deionized water for 30 minutes to obtain the polyamide reverse osmosis composite membrane.
The reverse osmosis composite membrane prepared by the method is tested for separation performance, the produced water flux is 67.5LMH, and the sodium chloride rejection rate is 97.9%.
Example 6
This example 6 provides a method for preparing a high-flux reverse osmosis composite membrane, including the following steps:
(1) dissolving m-phenylenediamine, 2-methylimidazole and histamine in water to obtain an aqueous phase solution, wherein the mass concentration of the m-phenylenediamine is 2.0%, the mass concentration of the 2-methylimidazole is 2.5% and the mass concentration of the histamine is 0.15%;
(2) soaking the polyimide ultrafiltration membrane in the aqueous phase solution prepared in the step (1) for 5min, taking out, and drying the residual aqueous solution on the surface of the membrane by a roller;
(3) dissolving trimesoyl chloride in isopar E to obtain an oil phase solution with the mass fraction of 2.0%;
(4) slowly pouring the oil phase solution obtained in the step (3) onto the upper surface of the membrane obtained in the step (2), initiating an interfacial polymerization reaction, continuing for 30 seconds to form a cross-linked polyamide separation layer, and pouring the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (4) at 60 ℃ for 5 minutes, and then soaking the membrane in deionized water for 30 minutes to obtain the polyamide reverse osmosis composite membrane.
The reverse osmosis composite membrane prepared by the method is tested for separation performance, the water production flux is 47.5LMH, and the sodium chloride rejection rate is 98.1%.
Example 7
This example 7 provides a method for preparing a high flux reverse osmosis composite membrane, including the following steps:
(1) dissolving m-phenylenediamine and 2-methylimidazole in water to obtain an aqueous phase solution, wherein the mass concentration of the m-phenylenediamine is 5.0%, and the mass concentration of the 2-methylimidazole is 2.5%;
(2) soaking the polypropylene ultrafiltration membrane in the aqueous phase solution prepared in the step (1) for 5min, taking out, and drying the residual aqueous solution on the surface of the membrane by a roller;
(3) dissolving trimesoyl chloride in n-hexane to obtain an oil phase solution with the mass fraction of 0.5%;
(4) slowly pouring the oil phase solution obtained in the step (3) onto the upper surface of the membrane obtained in the step (2), initiating an interfacial polymerization reaction, forming a cross-linked polyamide separation layer for 120s, and pouring out the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (4) at 60 ℃ for 2 minutes, and then soaking the membrane in deionized water for 30 minutes to obtain the polyamide reverse osmosis composite membrane.
The reverse osmosis composite membrane prepared by the method is tested for separation performance, the water production flux is 40.7LMH, and the sodium chloride rejection rate is 97.7%.
The parts not mentioned above can be realized by referring to the prior art.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.
Claims (9)
1. A preparation method of a high-flux reverse osmosis composite membrane is characterized by comprising the following steps:
(1) dissolving m-phenylenediamine and an imidazole additive in water, and fully stirring to obtain an aqueous phase solution;
(2) soaking the porous base membrane in the aqueous phase solution prepared in the step (1) for 1-5 min, taking out, and drying the residual aqueous phase solution on the surface of the porous base membrane by air knife drying or roller drying;
(3) dissolving trimesoyl chloride in an organic solvent and fully stirring to obtain a trimesoyl chloride oil phase solution;
(4) slowly pouring the trimesoyl chloride oil phase solution prepared in the step (3) onto the upper surface of the membrane obtained in the step (2), carrying out interfacial polymerization reaction for 10-120 s to form a cross-linked polyamide separation layer, and pouring the residual trimesoyl chloride oil phase solution from the upper part of the membrane;
(5) and (3) carrying out heat treatment on the membrane obtained in the step (4) at 50-80 ℃ for 2-30 min, and then soaking in deionized water to obtain the polyamide reverse osmosis composite membrane.
2. The method for preparing a high-throughput reverse osmosis composite membrane according to claim 1, wherein the imidazole additive in the step (1) is an imidazole compound containing a secondary amine group.
3. The method for preparing a high flux reverse osmosis composite membrane according to claim 2, wherein the imidazole additive in step (1) is at least one of imidazole, 2-methylimidazole, 3-methylimidazole, 4-methylimidazole, 2, 4-dimethylimidazole, 4- (hydroxymethyl) imidazole, 2-ethyl-4-methylimidazole and histamine.
4. The preparation method of the high-flux reverse osmosis composite membrane according to claim 1, wherein the mass concentration of m-phenylenediamine in the step (1) is 0.1-5%, and the mass concentration of the imidazole additive is 0.1-5%.
5. The preparation method of the high-flux reverse osmosis composite membrane according to claim 1, wherein the porous base membrane in the step (2) is one of a polysulfone ultrafiltration membrane, a polyethersulfone ultrafiltration membrane, a polyimide ultrafiltration membrane, a polyacrylonitrile ultrafiltration membrane, a polyethylene ultrafiltration membrane or a polypropylene ultrafiltration membrane.
6. The method for preparing a high-flux reverse osmosis composite membrane according to claim 1, wherein the organic solvent in the step (3) is at least one of hexane, cyclohexane, n-heptane, toluene, xylene, isopar G, isopar E, isopar H, isopar L or isopar M.
7. The method for preparing a high-flux reverse osmosis composite membrane according to claim 1, wherein the mass concentration of the trimesoyl chloride oil phase solution in the step (3) is 0.01-2%.
8. The method for preparing a high-flux reverse osmosis composite membrane according to claim 1, wherein the soaking time in deionized water in the step (5) is 10-60 min.
9. A high flux reverse osmosis composite membrane prepared by the method of any one of claims 1 to 8.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114405292A (en) * | 2022-03-01 | 2022-04-29 | 苏州仕净科技股份有限公司 | Novel composite nanofiltration membrane modified by ionic liquid and preparation method and application thereof |
| CN115350598A (en) * | 2022-07-05 | 2022-11-18 | 东北电力大学 | Method for preparing nanofiltration membrane by using 1-methylimidazole as water phase additive |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114405292A (en) * | 2022-03-01 | 2022-04-29 | 苏州仕净科技股份有限公司 | Novel composite nanofiltration membrane modified by ionic liquid and preparation method and application thereof |
| CN114405292B (en) * | 2022-03-01 | 2023-10-27 | 苏州仕净科技股份有限公司 | Composite nanofiltration membrane modified by ionic liquid and preparation method and application thereof |
| CN115350598A (en) * | 2022-07-05 | 2022-11-18 | 东北电力大学 | Method for preparing nanofiltration membrane by using 1-methylimidazole as water phase additive |
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