Composite membranes, methods of making and using the same

Abstract

The present application relates to a kind of composite film and its preparation method and application, wherein, the preparation method of composite film, it includes the following steps: multiple amine, water-soluble polymer, crosslinking agent, acid absorbent and water are mixed, obtain reversible hydrogel, wherein, water-soluble polymer is selected from at least one in guar gum, carrageenan;Providing porous support film, reversible hydrogel is placed on the surface of porous support film, forms hydrogel layer, and hydrogel layer extends from surface to the inside of porous support film;Under the irradiation of ultraviolet light, oil phase solution is placed on the surface of hydrogel layer away from porous support film, wherein, oil phase solution includes multiple acyl chloride, polyvinyl alcohol cinnamate and isomeric alkane solvent;And heat treatment and acid treatment are sequentially carried out, obtain composite film.The composite film prepared by the preparation method of composite film of the present application has high water flux and desalination rate when applied to water treatment.

Description

Technical Field

[0001] This invention relates to the field of water treatment filtration membrane technology, and in particular to composite membranes, their preparation methods, and applications. Background Technology

[0002] Composite membranes have been widely used in various fields such as water treatment, medicine, energy, and chemical engineering due to their advantages such as low energy consumption and minimal environmental pollution. There are many methods for preparing composite membranes, among which interfacial polymerization is a commonly used method. However, composite membranes prepared by traditional interfacial polymerization methods generally suffer from high desalination rates but low water flux.

[0003] To improve the water flux of composite membranes, several methods have emerged in the market, including: First, adding nanoparticles to the aqueous or oil phase during membrane preparation. However, this method easily leads to nanoparticle aggregation, and the nanoparticles are prone to detachment or escape due to a lack of effective adhesion to the separation layer, posing a drinking water safety risk. Second, adding hydrophilic substances to the aqueous phase. However, this method is not very effective in improving membrane flux because the hydrophilic substances have difficulty diffusing into the oil phase. Third, adding ester plasticizers to the oil phase. While this method can increase water flux, it generally reduces the desalination rate of the composite membrane. Fourth, coating the surface of the composite membrane with a hydrophilic substance after preparation. However, this method carries the risk of the hydrophilic substance detaching, thus affecting the improvement in water flux.

[0004] It is evident that composite membranes prepared using traditional methods still cannot simultaneously achieve high water flux and high desalination rate. Summary of the Invention

[0005] Therefore, it is necessary to address the problem that composite membranes prepared by traditional methods cannot simultaneously achieve high water flux and desalination rate. This paper proposes a composite membrane, its preparation method, and its application, which can simultaneously achieve high water flux and desalination rate when used in water treatment.

[0006] A method for preparing a composite membrane includes the following steps:

[0007] A reversible hydrogel is obtained by mixing a polyamine, a water-soluble polymer, a crosslinking agent, an acid scavenger, and water, wherein the water-soluble polymer is selected from at least one of guar gum and carrageenan.

[0008] A porous support membrane is provided, and the reversible hydrogel is placed on the surface of the porous support membrane to form a hydrogel layer, the hydrogel layer extending from the surface into the interior of the porous support membrane.

[0009] Under ultraviolet light irradiation, an oil phase solution is placed on the surface of the hydrogel layer away from the porous support membrane, wherein the oil phase solution includes polyacrylamide chloride, polyvinyl cinnamate and isoparaffin solvent;

[0010] Then, heat treatment and acid treatment are performed sequentially to obtain a composite membrane.

[0011] In one embodiment, in the step of mixing the polyamine, the water-soluble polymer, the crosslinking agent, the acid scavenger, and the water, the mass fraction of the water-soluble polymer is 0.01%-0.1%.

[0012] In one embodiment, in the step of mixing the polyamine, water-soluble polymer, crosslinking agent, acid scavenger, and water, the mass fraction of the crosslinking agent is 0.5%-1.5%.

[0013] And / or, the crosslinking agent is selected from at least one of boric acid and sodium borate.

[0014] In one embodiment, the polyamine in the reversible hydrogel has a mass fraction of 0.5%-1.5%;

[0015] And / or, the polyamine is selected from at least one of polyethyleneimine, piperazine, m-phenylenediamine, tetraethylenepentamine, and triethylenediamine.

[0016] In one embodiment, the acid-absorbing agent has a mass fraction of 1%-2% in the reversible hydrogel;

[0017] And / or, the acid absorbent is selected from at least one of triethylamine, sodium hydroxide, potassium hydroxide, sodium carbonate, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, and potassium dihydrogen phosphate.

[0018] In one embodiment, the polyacrylamide chloride has a mass fraction of 0.1%-0.5% in the oil phase solution;

[0019] And / or, the polyacryl chloride is selected from at least one of pyromellitic chloroformyl chloride, isophthaloyl chloride, and terephthaloyl chloride.

[0020] In one embodiment, the polyvinyl cinnamate in the oil phase solution has a mass fraction of 0.1%-0.3%.

[0021] In one embodiment, during the acid treatment process, a dilute acid solution with a pH of 4-6 is used for acid treatment;

[0022] And / or, during the heat treatment process, the heat treatment time is 1 min to 5 min, and the heat treatment temperature is 60℃ to 100℃;

[0023] And / or, during ultraviolet light irradiation, the ultraviolet light wavelength is 280nm-400nm and the ultraviolet light intensity is 0.4W / m. 2 -1W / m 2 .

[0024] Meanwhile, the present invention also provides a composite membrane, which is prepared by the composite membrane preparation method described above.

[0025] Furthermore, the present invention also provides an application of the composite membrane as described above in a water treatment device.

[0026] The porous support membrane has finger-like or sponge-like pores on its surface. In the preparation method of the composite membrane described in this invention, guar gum or carrageenan undergoes cross-linking under the action of a cross-linking agent to form a reversible hydrogel, while polyamines and acid scavengers are dispersed in the reversible hydrogel. When the reversible hydrogel is placed on the surface of the porous support membrane, it can enter the pores of the membrane, fill the pores, and extend to the surface of the porous support membrane to form a hydrogel layer covering the surface of the porous support membrane.

[0027] When the oil phase solution is placed on the surface of the hydrogel layer, the polyacrylamide chloride in the oil phase solution will also enter the hydrogel layer and undergo interfacial polymerization with the polyamine in the hydrogel layer to form a polyamide layer. The polyamide layer is embedded in the pores of the porous support membrane. At the same time, the polyvinyl cinnamate in the oil phase solution will undergo polymerization under ultraviolet light to form an irreversible gel layer. This results in the formation of an interpenetrating three-dimensional network between the polyamide layer, the hydrogel layer, and the irreversible gel layer, which are tightly bonded together.

[0028] Meanwhile, since the hydrogel layer can hydrolyze under acidic conditions, when acid treatment is performed, the hydrogel layer undergoes hydrolysis. On the one hand, this will correspondingly increase the water production channels, which to some extent avoids the problem that the overall interpenetrating three-dimensional network formed between the polyamide layer, hydrogel layer, and irreversible gel layer may be too dense and affect the water flux. On the other hand, it forms a separation layer composed of the polyamide layer and the irreversible gel layer, thereby increasing the water production channels of the composite membrane and effectively increasing the water flux of the composite membrane.

[0029] In addition, unlike the porous support membrane whose pores are finger-like or sponge-like, the hydrogel layer has a three-dimensional network structure. Therefore, the hydrogel layer can protect the pores of the porous support membrane and prevent the pores of the porous support membrane from being blocked by the separation layer, thereby further improving the water flux of the composite membrane.

[0030] Therefore, the composite membrane prepared by the method of this application has a separation layer consisting of a polyamide layer and an irreversible gel layer, which enables it to have both high water flux and desalination rate when used in water treatment. Attached Figure Description

[0031] Figure 1 This is an electron microscope image of the composite membrane prepared in Example 1 of the present invention;

[0032] Figure 2 This is an electron microscope image of the composite membrane prepared in Comparative Example 3 of the present invention;

[0033] Figure 3 This is an electron microscope image of the composite membrane prepared in Comparative Example 5 of the present invention. Detailed Implementation

[0034] The following will further explain the composite membrane provided by the present invention, its preparation method, and its application.

[0035] The method for preparing the composite membrane provided by the present invention includes the following steps:

[0036] S1. Mix polyamine, water-soluble polymer, crosslinking agent, acid scavenger and water to obtain a reversible hydrogel, wherein the water-soluble polymer is selected from at least one of guar gum and carrageenan.

[0037] S2. Provide a porous support membrane, place the reversible hydrogel on the surface of the porous support membrane to form a hydrogel layer, the hydrogel layer extending from the surface into the interior of the porous support membrane;

[0038] S3. Under ultraviolet light irradiation, an oil phase solution is placed on the surface of the hydrogel layer away from the porous support membrane, wherein the oil phase solution includes polyacrylamide chloride, polyvinyl cinnamate and isoparaffin solvent.

[0039] S4. Perform heat treatment and acid treatment in sequence to obtain composite membrane.

[0040] In step S1, after the polyamine, water-soluble polymer, crosslinking agent, acid scavenger and water are mixed, guar gum or carrageenan will crosslink under the action of the crosslinking agent to form a reversible hydrogel with a three-dimensional network structure, while the polyamine and acid scavenger are dispersed in the reversible hydrogel.

[0041] In step S2, the porous support membrane includes at least one of polysulfone membrane, polypropylene membrane, or polyacrylonitrile membrane. Polysulfone is inexpensive and readily available, simple to prepare, has good mechanical strength, good resistance to compression compaction, stable chemical properties, is non-toxic, and resistant to biodegradation. Therefore, polysulfone membrane is preferred as the porous support membrane. It should be noted that the porous support membrane can be prepared in-house or purchased commercially.

[0042] In one embodiment, the pore size of the porous support membrane is 16nm-25nm.

[0043] To increase the strength of the composite membrane, in one embodiment, a nonwoven fabric layer is also provided, which is stacked with the porous support membrane, and the reversible hydrogel and the oil phase solution are sequentially placed on the surface of the porous support membrane opposite to the nonwoven fabric layer.

[0044] In step S2, the surface of the porous support membrane has membrane pores in the form of finger-like or sponge-like pores. When the reversible hydrogel is placed on the surface of the porous support membrane, the reversible hydrogel can enter the membrane pores of the porous support membrane. The reversible hydrogel can fill the membrane pores and extend to the surface of the porous support membrane to form a hydrogel layer with a three-dimensional network structure, covering the surface of the porous support membrane. That is, the hydrogel layer extends from the surface to the interior of the porous support membrane. At the same time, polyamines and acid scavengers are dispersed in the hydrogel layer.

[0045] Unlike porous support membranes, which have finger-like or sponge-like pores, the hydrogel layer has a three-dimensional network structure. Therefore, the hydrogel layer can protect the pores of the porous support membrane and prevent them from being blocked by the separation layer, thereby further improving the water flux of the composite membrane.

[0046] In step S3, when the oil phase solution is placed on the surface of the hydrogel layer, the polyacrylamide chloride in the oil phase solution will also enter the hydrogel layer and undergo interfacial polymerization with the polyamine in the hydrogel layer to form a polyamide layer. The polyamide layer is embedded in the pores of the porous support membrane. At the same time, under ultraviolet light, the polyvinyl cinnamate in the oil phase solution will undergo polymerization to form an irreversible gel layer with a three-dimensional network structure. This results in the formation of an interpenetrating three-dimensional network between the polyamide layer, the hydrogel layer, and the irreversible gel layer, which are tightly bonded together. At this time, the interpenetrating three-dimensional network can serve as a pre-fabricated separation layer.

[0047] Meanwhile, since the hydrogel layer can be hydrolyzed under acidic conditions, in step S4, when acid treatment is performed, the hydrogel layer undergoes hydrolysis. On the one hand, this will correspondingly increase the water production channels, and to a certain extent avoid the problem that the interpenetrating three-dimensional network formed between the polyamide layer, the hydrogel layer, and the irreversible gel layer may be too dense and affect the water flux. On the other hand, it makes the pre-fabricated separation layer a separation layer composed of the polyamide layer and the irreversible gel layer, thereby increasing the water production channels of the composite membrane and effectively increasing the water flux of the composite membrane.

[0048] In addition, while polyacrylamide chlorides and polyamines undergo interfacial polymerization to form a polyamide layer, they also produce hydrochloric acid as a byproduct. The hydrochloric acid is absorbed by the acid scavenger in the hydrogel layer, thus ensuring that the interfacial polymerization reaction proceeds in the forward direction.

[0049] Therefore, the composite membrane prepared by the method of this application has a separation layer consisting of a polyamide layer and an irreversible gel layer, which enables it to have both high water flux and desalination rate when used in water treatment.

[0050] To better form a reversible hydrogel and further improve the water flux of the composite membrane, preferably, in the step of mixing the polyamine, water-soluble polymer, crosslinking agent, acid scavenger, and water, the mass fraction of the water-soluble polymer is 0.01%-0.1%, the mass fraction of the crosslinking agent is 0.5%-1.5%, the mass fraction of the polyamine is 0.5%-1.5%, and the mass fraction of the acid scavenger is 1%-2%. This configuration allows the water-soluble polymer to undergo sufficient crosslinking under the action of the crosslinking agent, forming a reversible hydrogel with a three-dimensional network structure. This ensures that the mass fraction of the polyamine in the reversible hydrogel is 0.5%-1.5%, and the mass fraction of the acid scavenger is 1%-2%. This, in turn, facilitates the reversible hydrogel serving as the framework for the subsequently formed polyamide layer, forming an interpenetrating three-dimensional network structure with the polyamide layer.

[0051] In one embodiment, the crosslinking agent is selected from at least one of boric acid and sodium borate.

[0052] A polyamide layer is formed by interfacial polymerization of polyamines and polyacrylamide chlorides. In one embodiment, the polyamine has a mass fraction of 0.5%-1.5% in the reversible hydrogel, and the polyacrylamide chloride has a mass fraction of 0.1%-0.5% in the oil phase solution. This configuration allows for more complete cross-linking of the polyamide layer, thereby increasing the water flux of the composite membrane.

[0053] In one embodiment, the polyamine is selected from at least one of polyethyleneimine, piperazine, m-phenylenediamine, tetraethylenepentamine, and triethylenediamine. More preferably, the polyamine is selected from m-phenylenediamine.

[0054] In one embodiment, the polyacryl chloride is selected from at least one of pyromellitic chloroformyl chloride, isophthaloyl chloride, and terephthaloyl chloride.

[0055] To better absorb the hydrochloric acid byproduct generated during the interfacial polymerization reaction between polyamines and polyacrylamide chlorides, and to further ensure the forward progress of the interfacial polymerization reaction between the polyamines and polyacrylamide chlorides, preferably, the acid scavenger in the reversible hydrogel has a mass fraction of 1%-2%; wherein, the acid scavenger is selected from at least one of triethylamine, sodium hydroxide, potassium hydroxide, sodium carbonate, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, and potassium dihydrogen phosphate. More preferably, the acid scavenger is selected from triethylamine.

[0056] To better facilitate the in-situ polymerization of polyvinyl cinnamate in the oil phase solution, forming an irreversible gel with a three-dimensional network structure and further improving the water flux of the composite membrane, preferably, the mass fraction of polyvinyl cinnamate in the oil phase solution is 0.1%-0.3%. This configuration allows for sufficient interpenetration between the irreversible gel layer, the polyamide layer, and the hydrogel layer, forming an interpenetrating three-dimensional network structure, i.e., a pre-fabricated separation layer, thereby increasing the water flux of the composite membrane.

[0057] In one embodiment, the isoparaffin solvent is selected from at least one of Isopar-E, Isopar-G, and Isopar-L.

[0058] To further control the reaction rate and extent of in-situ polymerization of polyvinyl cinnamate, in one embodiment, in step S3, the ultraviolet light wavelength is 280nm-400nm and the ultraviolet light intensity is 0.4W / m. 2 -1W / m 2 This configuration facilitates the formation of an irreversible gel with a three-dimensional network structure from polyvinyl cinnamate, which is used to form an interpenetrating three-dimensional network structure with the polyamide layer, thereby increasing the water flux of the composite membrane.

[0059] To better facilitate the hydrolysis of the formed hydrogel layer and thus increase the water flux of the composite membrane, preferably, in step S4, a dilute acid solution with a pH of 4-6 is used for acid treatment. More preferably, the dilute acid solution is selected from hydrochloric acid, and the acid treatment time is 1 min-4 min. This setting allows the hydrogel layer to undergo sufficient hydrolysis under acidic conditions, leaving water production channels, thereby improving the water flux of the composite membrane.

[0060] In one embodiment, in step S4, the heat treatment time is 1 min to 5 min; the heat treatment temperature is 60℃ to 100℃. This setting ensures the integrity and uniformity of the crosslinking of the polyamide layer, thereby ensuring the water flow of the composite membrane.

[0061] Furthermore, this invention also provides a composite membrane prepared by the above-described method, which, when applied to water treatment, exhibits both high water flux and high desalination rate. In addition, this invention provides an application of the composite membrane described above in a water treatment device.

[0062] It should be noted that the composite membrane in this application can be used as a reverse osmosis membrane, forward osmosis membrane or nanofiltration membrane in water treatment devices.

[0063] In one embodiment, the water treatment device can be a water purifier, in which case the composite membrane can be used as a reverse osmosis membrane in the water purifier. During the water purification process, the raw water to be purified enters from the separation layer of the composite membrane, and under pressure, the raw water permeates through the composite membrane to form pure water.

[0064] The composite membrane, its preparation method, and its application will be further described below through specific embodiments.

[0065] It should be noted that, unless otherwise specified, all reagents and raw materials involved in this invention can be obtained through commercial means.

[0066] Example 1

[0067] m-phenylenediamine, guar gum, sodium borate, and triethylamine were added to water and mixed evenly to obtain a reversible hydrogel. In the step of mixing m-phenylenediamine, guar gum, sodium borate, triethylamine, and water, the mass fraction of guar gum was 0.02%, the mass fraction of sodium borate was 0.6%, the mass fraction of m-phenylenediamine was 0.5%, and the mass fraction of triethylamine was 1%.

[0068] A polysulfone porous support membrane is provided, with a pore size of 18 nm.

[0069] Trimethylbenzene chloride (TMC) and polyvinyl cinnamate were added to an isoparaffin solvent (Isopar-L) and mixed thoroughly to obtain an oil phase solution, wherein the mass fraction of TMC and polyvinyl cinnamate in the oil phase solution was 0.1%.

[0070] First, the reversible hydrogel obtained above is coated onto the polysulfone porous support membrane. After standing for 60 seconds, the excess reversible hydrogel is poured off, and the membrane surface is dried with cold air to form a hydrogel layer. The hydrogel layer is then tested under ultraviolet light at a wavelength of 300 nm and an ultraviolet intensity of 0.6 W / m. 2 Under ultraviolet light irradiation, the oil phase solution obtained above was applied to the surface of the hydrogel layer away from the polysulfone porous support membrane. After standing for 30 seconds, excess oil phase solution was discarded. Then, the layer was directly placed in a 100°C forced-air drying oven for 2 minutes for heat treatment. It was then removed and subjected to acid treatment in a pH 5 hydrochloric acid solution for 2 minutes to obtain… Figure 1 The composite membrane shown.

[0071] The composite membrane prepared in this embodiment was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0072] Example 2

[0073] m-phenylenediamine, carrageenan, sodium borate, and triethylamine were added to water and mixed evenly to obtain a reversible hydrogel. In the step of mixing m-phenylenediamine, carrageenan, sodium borate, triethylamine, and water, the mass fraction of carrageenan was 0.04%, the mass fraction of sodium borate was 0.8%, the mass fraction of m-phenylenediamine was 0.7%, and the mass fraction of triethylamine was 1.2%.

[0074] A polysulfone porous support membrane is provided, with a pore size of 18 nm.

[0075] Trimethylbenzene chloride (TMC) and polyvinyl cinnamate were added to an isoparaffin solvent (Isopar-L) and mixed thoroughly to obtain an oil phase solution, wherein the mass fraction of TMC in the oil phase solution was 0.3% and the mass fraction of polyvinyl cinnamate in the oil phase solution was 0.15%.

[0076] First, the reversible hydrogel obtained above is coated onto the polysulfone porous support membrane. After standing for 60 seconds, the excess reversible hydrogel is poured off, and the membrane surface is dried with cold air to form a hydrogel layer. The hydrogel layer is then tested under ultraviolet light at a wavelength of 300 nm and an ultraviolet intensity of 0.6 W / m. 2 Under ultraviolet light irradiation, the oil phase solution obtained above is applied to the surface of the hydrogel layer away from the polysulfone porous support membrane. After standing for 30 seconds, the excess oil phase solution is poured off, and then it is directly placed in a 90°C forced-air drying oven for heat treatment for 3 minutes. After taking it out, it is placed in a hydrochloric acid solution with a pH of 5.5 for acid treatment for 2 minutes to obtain the composite membrane.

[0077] The composite membrane prepared in this embodiment was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0078] Example 3

[0079] Piperazine, guar gum, boric acid, and triethylamine were added to water and mixed evenly to obtain a reversible hydrogel. In the step of mixing piperazine, guar gum, boric acid, triethylamine, and water, the mass fraction of guar gum was 0.05%, the mass fraction of boric acid was 0.1%, the mass fraction of piperazine was 1%, and the mass fraction of triethylamine was 1.5%.

[0080] A polysulfone porous support membrane is provided, with a pore size of 18 nm.

[0081] Isophthaloyl chloride (TMC) and polyvinyl cinnamate were added to an isoparaffin solvent (Isopar-L) and mixed thoroughly to obtain an oil phase solution, wherein the mass fraction of isophthaloyl chloride (TMC) in the oil phase solution was 0.3% and the mass fraction of polyvinyl cinnamate in the oil phase solution was 0.2%.

[0082] First, the reversible hydrogel obtained above is coated onto the polysulfone porous support membrane. After standing for 60 seconds, the excess reversible hydrogel is poured off, and the membrane surface is dried with cold air to form a hydrogel layer. The hydrogel layer is then tested under ultraviolet light at a wavelength of 300 nm and an ultraviolet intensity of 0.6 W / m. 2 Under ultraviolet light irradiation, the oil phase solution obtained above is applied to the surface of the hydrogel layer away from the polysulfone porous support membrane. After standing for 30 seconds, the excess oil phase solution is poured off, and then it is directly placed in a 90°C forced-air drying oven for heat treatment for 3 minutes. After taking it out, it is placed in a hydrochloric acid solution with a pH of 5.5 for acid treatment for 2 minutes to obtain the composite membrane.

[0083] The composite membrane prepared in this embodiment was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0084] Example 4

[0085] m-phenylenediamine, guar gum, boric acid, and triethylamine were added to water and mixed evenly to obtain a reversible hydrogel. In the step of mixing m-phenylenediamine, guar gum, boric acid, triethylamine, and water, the mass fraction of guar gum was 0.1%, the mass fraction of boric acid was 1.5%, the mass fraction of m-phenylenediamine was 1.5%, and the mass fraction of triethylamine was 2%.

[0086] A polysulfone porous support membrane is provided, with a pore size of 20 nm.

[0087] Trimethylbenzene chloride (TMC) and polyvinyl cinnamate were added to an isoparaffin solvent (Isopar-L) and mixed thoroughly to obtain an oil phase solution, wherein the mass fraction of TMC in the oil phase solution was 0.5% and the mass fraction of polyvinyl cinnamate in the oil phase solution was 0.25%.

[0088] First, the reversible hydrogel obtained above was coated onto the polysulfone porous support membrane. After standing for 60 seconds, the excess reversible hydrogel was poured off, and the membrane surface was dried with cold air to form a hydrogel layer. The hydrogel layer was then tested under ultraviolet light at a wavelength of 320 nm and an ultraviolet intensity of 0.6 W / m. 2Under ultraviolet light irradiation, the oil phase solution obtained above is applied to the surface of the hydrogel layer away from the polysulfone porous support membrane. After standing for 30 seconds, the excess oil phase solution is poured off, and then it is directly placed in a 90°C forced-air drying oven for heat treatment for 3 minutes. After taking it out, it is placed in a hydrochloric acid solution with a pH of 5 for acid treatment for 3 minutes to obtain the composite membrane.

[0089] The composite membrane prepared in this embodiment was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0090] Example 5

[0091] Compared with Example 1, the only difference is that in Example 5, the mass fraction of polyvinyl cinnamate in the oil phase solution is 0.5% during the preparation of the oil phase solution, and all other conditions are the same, thus preparing the composite membrane.

[0092] The composite membrane prepared in this embodiment was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0093] Example 6

[0094] Compared with Example 1, the only difference is that in Example 6, the mass fraction of polyvinyl cinnamate in the oil phase solution was 0.08% during the preparation of the oil phase solution, and all other conditions were the same, thus obtaining the composite membrane.

[0095] The composite membrane prepared in this embodiment was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0096] Example 7

[0097] Compared with Example 1, the only difference is that in Example 7, m-phenylenediamine, guar gum, carrageenan, boric acid, and triethylamine were added to water and mixed evenly to obtain a reversible hydrogel. In the step of mixing m-phenylenediamine, guar gum, carrageenan, boric acid, triethylamine, and water, the mass fraction of guar gum was 0.02%, the mass fraction of carrageenan was 0.03%, the mass fraction of boric acid was 0.1%, the mass fraction of m-phenylenediamine was 1%, and the mass fraction of triethylamine was 1.5%. All other conditions were the same, and the composite membrane was prepared.

[0098] The composite membrane prepared in this embodiment was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0099] Example 8

[0100] Compared with Example 1, the only difference is that in Example 8, the mass fraction of guar gum is 0.15% in the step of mixing m-phenylenediamine, guar gum, sodium borate, triethylamine and water, and all other conditions are the same to prepare the composite membrane.

[0101] The composite membrane prepared in this embodiment was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0102] Example 9

[0103] Compared with Example 1, the only difference is that in Example 9, the mass fraction of guar gum is 0.08% in the step of mixing m-phenylenediamine, guar gum, sodium borate, triethylamine and water, and all other conditions are the same to prepare the composite membrane.

[0104] The composite membrane prepared in this embodiment was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0105] Comparative Example 1

[0106] Compared with Example 1, the only difference is that in Comparative Example 1, guar gum and sodium borate were not contained in the process of preparing the reversible hydrogel, while all other conditions were the same, and a composite membrane was prepared.

[0107] The composite membrane prepared in the comparative example was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0108] Comparative Example 2

[0109] Compared with Example 1, the only difference is that in Comparative Example 2, polyvinyl cinnamate was not contained in the preparation of the oil phase solution, while all other conditions were the same, and a composite membrane was prepared.

[0110] The composite membrane prepared in the comparative example was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0111] Comparative Example 3

[0112] Compared to Example 1, the only difference in Comparative Example 3 is that polyvinyl alcohol was used instead of guar gum in the preparation of the reversible hydrogel, while all other conditions remained the same, resulting in the preparation of the following: Figure 2 The composite membrane shown.

[0113] Comparative Example 4

[0114] Compared with Example 1, the only difference is that in Comparative Example 4, after heat treatment, no acid treatment was performed, and the composite membrane was obtained directly.

[0115] Comparative Example 5

[0116] Compared with Example 1, the only difference in Comparative Example 5 is that guar gum and sodium borate were not included in the preparation of the reversible hydrogel, and polyvinyl cinnamate was not included in the preparation of the oil phase solution. All other conditions were the same, and the prepared hydrogel was as shown in Example 5. Figure 3 The composite membrane shown.

[0117] The composite membrane prepared in the comparative example was subjected to performance testing. The test conditions were as follows: test pressure was 0.75 MPa, concentrate flow rate was 1.0 GPM, ambient temperature was 25℃, concentrate pH was 6.5-7.5, and concentrate was 500 ppm sodium chloride aqueous solution. The test results are shown in Table 1.

[0118] Table 1

[0119] Membrane water flux / LMH Retention rate / % Example 1 125 99.3 Example 2 118 99.4 Example 3 158 98.1 Example 4 133 99.1 Example 5 99 99.4 Example 6 115 98.4 Example 7 121 99.4 Example 8 99 99.4 Example 9 93 99.3 Comparative Example 1 70 98.3 Comparative Example 2 81 98.5 Comparative Example 3 77 98.9 Comparative Example 4 81 99.3 Comparative Example 5 43 98.3

[0120] It should be noted that in Table 1, the membrane water flux (F) is calculated from the volume of water passing through the reverse osmosis membrane within a certain time period, and the formula is: F=V / (A×T), where V is the volume of water passing through the reverse osmosis membrane per unit time, A is the effective membrane area, and T is time.

[0121] The rejection rate (R) is calculated using the concentrations of the concentrate and the permeate. The formula is: R = (1 - C1 / C0) × 100%, where C1 is the concentration of the concentrate and C0 is the concentration of the permeate.

[0122] As shown in Table 1, the composite membrane prepared using this application exhibits both high water flux and high desalination rate. Specifically, compared to the data from Examples 1, 5, and 6, both high and low amounts of polyvinyl cinnamate affect the water flux of the composite membrane. Similarly, compared to the data from Examples 1, 8, and 9, both high and low amounts of guar gum also affect the water flux of the composite membrane.

[0123] Compared with the data from Example 1, Comparative Example 1, and Comparative Example 2, it is evident that the reversible hydrogel formed in this application has a synergistic effect with the irreversible gel formed in the oil phase solution. Furthermore, compared with the data from Example 1 and Comparative Example 3, it is evident that using guar gum to form a reversible hydrogel can effectively increase the water flux of the composite membrane. In addition, compared with the data from Example 1 and Comparative Example 4, it is evident that the hydrolysis of the hydrogel layer can effectively increase the water flux of the composite membrane.

[0124] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0125] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a composite membrane, characterized in that, Includes the following steps: A reversible hydrogel is obtained by mixing a polyamine, a water-soluble polymer, a crosslinking agent, an acid scavenger, and water, wherein the water-soluble polymer is selected from at least one of guar gum and carrageenan, and the crosslinking agent is selected from at least one of boric acid and sodium borate. A porous support membrane is provided, and the reversible hydrogel is placed on the surface of the porous support membrane to form a hydrogel layer, the hydrogel layer extending from the surface into the interior of the porous support membrane. Under ultraviolet light irradiation, an oil phase solution is placed on the surface of the hydrogel layer away from the porous support membrane, wherein the oil phase solution includes polyacrylamide chloride, polyvinyl cinnamate and isoparaffin solvent; and heat treatment and acid treatment are performed sequentially to obtain a composite membrane.

2. The method for preparing the composite membrane according to claim 1, characterized in that, In the step of mixing the polyamine, water-soluble polymer, crosslinking agent, acid scavenger, and water, the mass fraction of the water-soluble polymer is 0.01%-0.1%.

3. The method for preparing the composite membrane according to claim 1, characterized in that, In the step of mixing polyamine, water-soluble polymer, crosslinking agent, acid scavenger and water, the mass fraction of the crosslinking agent is 0.5%-1.5%.

4. The method for preparing the composite membrane according to claim 1, characterized in that, The polyamine has a mass fraction of 0.5%-1.5% in the reversible hydrogel; And / or, the polyamine is selected from at least one of polyethyleneimine, piperazine, m-phenylenediamine, tetraethylenepentamine, and triethylenediamine.

5. The method for preparing the composite membrane according to claim 1, characterized in that, The acid absorbent has a mass fraction of 1%-2% in the reversible hydrogel; And / or, the acid absorbent is selected from at least one of triethylamine, sodium hydroxide, potassium hydroxide, sodium carbonate, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, and potassium ammonium dihydrogen phosphate.

6. The method for preparing the composite membrane according to any one of claims 1 to 5, characterized in that, The mass fraction of the polyacrylamide chloride in the oil phase solution is 0.1%-0.5%; And / or, the polyacryl chloride is selected from at least one of pyromellitic chloroformyl chloride, isophthaloyl chloride, and terephthaloyl chloride.

7. The method for preparing the composite membrane according to claim 6, characterized in that, The mass fraction of the polyvinyl cinnamate in the oil phase solution is 0.1%-0.3%.

8. The method for preparing the composite membrane according to claim 1, characterized in that, During the acid treatment process, a dilute acid solution with a pH of 4-6 is used for acid treatment; And / or, during the heat treatment process, the heat treatment time is 1 min to 5 min, and the heat treatment temperature is 60℃ to 100℃; And / or, during ultraviolet irradiation, the ultraviolet wavelength is 280nm-400nm and the ultraviolet intensity is 0.4W / m. 2 -1W / m 2 .

9. A composite membrane, characterized in that, The composite membrane is prepared by the method for preparing the composite membrane according to any one of claims 1 to 8.

10. The application of the composite membrane as described in claim 9 in a water treatment device.

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