Seawater desalination reverse osmosis membrane and preparation method thereof

Abstract

The invention relates to the technical field of water treatment membranes, in particular to a seawater desalination reverse osmosis membrane and a preparation method thereof. The seawater desalination reverse osmosis membrane comprises a non-woven fabric layer, a supporting layer, a functional layer and a polyamide separation layer which are in contact in sequence, and the component of the functional layer is cup-shaped polymer tetrahydroxy calix [4] arene tetrasulfonic acid. The tetrahydroxy calix [4] arene tetrasulfonic acid can be firmly bonded on the surface of polysulfone due to the interaction of a sulfonic acid group and a hydrogen bond of polysulfone. When the polyamide separation layer is prepared by interfacial polymerization, the flux of the seawater desalination reverse osmosis membrane can be improved by tetrahydroxy calix [4] arene tetrasulfonic acid. In addition, due to the existence of sulfonic acid groups in tetrahydroxy calix [4] arene tetrasulfonic acid, the desalination rate of the seawater desalination reverse osmosis membrane can also be improved under the action of the charge effect. Therefore, the reverse osmosis membrane for seawater desalination is high in water flux and desalination rate.

Description

Technical Field

[0001] This invention relates to the field of water treatment membrane technology, and in particular to a seawater desalination reverse osmosis membrane and its preparation method. Background Technology

[0002] Water scarcity is one of the global challenges facing humanity today. Given the abundant reserves of seawater, desalination can be an ideal solution to the global freshwater crisis. Seawater desalination technologies mainly fall into two categories: thermal and membrane methods. Among them, membrane separation technology, represented by reverse osmosis membrane technology, can achieve highly efficient seawater desalination. Compared with thermal methods, it has advantages such as simple operation, low cost, and environmental friendliness, demonstrating unique advantages in the field of seawater desalination. However, the seawater desalination reverse osmosis membrane (SWRO), the core of the membrane-based seawater desalination process, still needs improvement to further reduce the cost of related infrastructure and system operation. According to modeling studies, given a daily water production and recovery rate, increasing the SWRO permeate flux by more than double can reduce the number of pressure vessels and energy consumption of the membrane system by 44% and 15%, respectively. Furthermore, according to relevant literature, when using seawater with a salinity of 3.5% (mass fraction) for desalination with a recovery rate of 50%, the thermodynamically theoretical minimum energy consumption is 1.06 kWh / m³. 3 However, even the more advanced seawater desalination plants currently available consume approximately 3-4 kWh / m³ of energy. 3 There is still a significant gap between the current value and the theoretical minimum, indicating room for further reduction. Therefore, it is of great significance to overcome the trade-off effect between the desalination rate and water flux of reverse osmosis membrane materials, while simultaneously improving the desalination rate and water flux of seawater desalination reverse osmosis membranes.

[0003] Seawater desalination reverse osmosis membranes are generally prepared using interfacial polymerization and are composite membranes, typically with a three-layer structure: a nonwoven fabric layer, a polysulfone layer, and a polyamide layer from bottom to top. The preparation methods for the polysulfone and polyamide layers are as follows: a casting solution is cast onto the nonwoven fabric layer, and a polysulfone-based membrane is obtained through phase inversion. The polysulfone-based membrane is then immersed in an aqueous solution containing amine monomers and other additives. After removal, excess solution is removed using a vacuum pump and air knife. An oil-phase solution containing acyl chloride monomers and other additives is then poured onto the membrane surface, where an interfacial polymerization reaction occurs. Excess oil-phase solution is removed by heating in an oven, yielding the polyamide layer. Subsequent rinsing and other post-treatment processes complete the seawater desalination reverse osmosis membrane. Conventionally prepared seawater desalination reverse osmosis membranes have the following drawbacks: low desalination rate limiting applications, and low flux resulting in high system energy consumption.

[0004] Currently, most research on preparing high-performance seawater desalination reverse osmosis membranes focuses on optimizing interfacial polymerization conditions, developing novel reactive monomers, and adding porous nanomaterials to fine-tune the performance of the polyamide layer, thereby further improving the membrane material's performance. However, these strategies cannot effectively balance the relationship between membrane desalination rate and water flux (the trade-off effect): typically, increasing membrane flux may sacrifice membrane desalination rate, or vice versa.

[0005] For example, existing technologies offer the following solutions: 1. Adding nanomaterials during the preparation of polysulfone-based membranes to optimize the interfacial polymerization reaction and form nanoflux, thereby improving the water flux and desalination rate of the membrane material; 2. Adding auxiliary agents and nanomaterials to the aqueous or organic phase during the interfacial polymerization reaction to improve the desalination rate and water flux of the membrane; 3. Physically coating the surface of the polyamide separation layer with polyvinyl alcohol (PVA) or further performing PVA crosslinking grafting on the membrane surface or inside the polyamide to improve the membrane's desalination rate and antifouling ability.

[0006] However, the above technical solutions also have the following technical defects: 1. Low flux results in high system energy consumption; 2. Overall desalination rate is low; 3. Although the introduction of nanomaterials can improve the separation performance and water permeability of the membrane, nanomaterials are expensive, difficult to obtain, and have process defects such as "agglomeration", making them unsuitable for large-scale industrial production; 4. Coating the membrane surface with PVA, chemically grafting PVA onto the membrane surface with polyamide, or grafting PVA into the polyamide can protect the separation layer on the membrane surface, thereby improving the membrane's antifouling ability and desalination rate, but it will reduce the membrane's water flux. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a seawater desalination reverse osmosis membrane and a method for preparing the same, wherein the seawater desalination reverse osmosis membrane has high water flux and desalination rate.

[0008] This invention provides a seawater desalination reverse osmosis membrane, comprising a nonwoven fabric layer, a support layer, a functional layer and a polyamide separation layer in sequential contact;

[0009] The functional layer is composed of cup-shaped polymer tetrahydroxycalix[4] aromatic tetrasulfonic acid.

[0010] Preferably, the functional layer is prepared by curing a tetrahydroxycalix[4] aromatic tetrasulfonic acid solution;

[0011] The tetrahydroxycalix[4] aryl tetrasulfonic acid solution comprises tetrahydroxycalix[4] aryl tetrasulfonic acid, glycerol and water.

[0012] Preferably, in the tetrahydroxycalix[4]arenetetrasulfonic acid solution, the mass content of tetrahydroxycalix[4]arenetetrasulfonic acid is 0.1%~2.0%; and the mass content of glycerol is 1%~3%.

[0013] Preferably, the polyamide separation layer is formed by an interfacial polymerization reaction between an aqueous solution and an oil solution on a functional layer;

[0014] The aqueous solution comprises amine monomers, surfactants, polar solvents, acid absorbents, and water;

[0015] The oil phase solution comprises an acyl chloride monomer and an oil phase solvent.

[0016] Preferably, the mass ratio of the amine monomer, surfactant, polar solvent, and water is 1~5:0.1~0.5:1~5:89.5~97.9;

[0017] The acid absorbent is used to adjust the pH value of the aqueous solution; the pH value of the aqueous solution is 7.0~8.0.

[0018] Preferably, the amine monomer is m-phenylenediamine; the surfactant is sodium dodecylbenzenesulfonate; the polar solvent is N-methylpyrrolidone; and the acid absorbent is sodium hydroxide.

[0019] Preferably, the acyl chloride monomer is pyromellitic trimethylolpropionate chloride; the oil phase solvent is Isopar G;

[0020] The mass content of acyl chloride monomer in the oil phase solution is 0.05%~0.5%.

[0021] This invention also provides a method for preparing the seawater desalination reverse osmosis membrane described above, comprising the following steps:

[0022] A. The casting solution is coated onto one side of the nonwoven fabric layer and cured into a film by phase inversion to obtain a base film; the base film includes a nonwoven fabric layer and a support layer formed on the nonwoven fabric layer;

[0023] B. A tetrahydroxycalix[4] aromatic tetrasulfonic acid solution is coated on one side of the support layer of the base film. After curing, a functional layer is formed.

[0024] C. Coat the functional layer with an aqueous solution, remove and allow it to dry slightly, then coat it with an oil solution. After heat curing, a polyamide separation layer is formed, resulting in a seawater desalination reverse osmosis membrane.

[0025] Preferably, in step C, the temperature of the thermosetting treatment is 70~90℃ and the time is 3~7 min.

[0026] Preferably, in step A, the phase transformation curing temperature is 20~40℃ and the time is 1~10 min.

[0027] This invention introduces cup-shaped polymer tetrahydroxycalix[4]arene tetrasulfonic acid (SCA) as a functional material to improve membrane performance for the first time. Unlike the general interfacial polymerization method for preparing seawater desalination reverse osmosis membranes, this invention pre-coats a layer of tetrahydroxycalix[4]arene tetrasulfonic acid (SCA) functional layer on the surface of the polysulfone-based membrane: First, due to the hydrogen bond interaction between the sulfonic acid group and the polysulfone, tetrahydroxycalix[4]arene tetrasulfonic acid can be firmly bonded to the polysulfone surface. Second, during the subsequent interfacial polymerization to prepare the polyamide separation layer, tetrahydroxycalix[4]arene tetrasulfonic acid will be embedded into the polyamide layer of the seawater desalination reverse osmosis membrane to form "cup-shaped" nanoscale channels, thereby increasing the flux of the seawater desalination reverse osmosis membrane. At the same time, since tetrahydroxycalix[4]arene tetrasulfonic acid contains sulfonic acid groups and hydroxyl groups, the hydrophilicity of the polyamide separation layer is improved, which will further increase the flux of the seawater desalination reverse osmosis membrane. In addition, due to the presence of sulfonic acid groups in tetrahydroxycalix[4]arenetetrasulfonic acid, the charge of the polyamide separation layer increases, and under the effect of charge, the desalination rate of the seawater desalination reverse osmosis membrane will also be improved. Attached Figure Description

[0028] Figure 1 This is a top view of the "cup-shaped" molecular structure of the tetrahydroxycalix[4]arene tetrasulfonic acid of the present invention;

[0029] Figure 2 This is a side view of the "cup-shaped" molecular structure of the tetrahydroxycalix[4]arene tetrasulfonic acid of the present invention. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention provides a seawater desalination reverse osmosis membrane, comprising a nonwoven fabric layer, a support layer, a functional layer and a polyamide separation layer in sequential contact;

[0032] The functional layer is composed of cup-shaped polymer tetrahydroxycalix[4]arene tetrasulfonic acid (SCA). The tetrahydroxycalix[4]arene tetrasulfonic acid (SCA) has the structure shown in Formula I;

[0033] Formula I.

[0034] Figure 1This is a top view of the "cup-shaped" molecular structure of the tetrahydroxycalix[4]arene tetrasulfonic acid of the present invention; Figure 2 This is a side view of the "cup-shaped" molecular structure of the tetrahydroxycalix[4]arene tetrasulfonic acid of the present invention.

[0035] In some embodiments of the present invention, the thickness of the nonwoven fabric layer is 70~120 μm, for example 100 μm. The air permeability of the nonwoven fabric layer is 0.5~4 cc / cm. 2 / s, for example, 1.5 cc / cm 2 / s.

[0036] In some embodiments of the present invention, the support layer is formed by curing a casting solution onto the surface of a nonwoven fabric layer; the casting solution comprises polysulfone and an organic solvent in a mass ratio of 12-25:75-88. The organic solvent includes, but is not limited to, N,N-dimethylformamide (DMF). The casting solution is obtained by dissolving polysulfone in an organic solvent. The dissolution is carried out by stirring and mixing. The mixing temperature is 70-80°C, for example, 75°C. After dissolution, the process further includes: static degassing. The static degassing time is 12-36 hours.

[0037] In some embodiments of the present invention, the thickness of the support layer is 110~160 μm, for example 150 μm.

[0038] In some embodiments of the present invention, the functional layer is prepared by curing a tetrahydroxycalix[4]arylenetetrasulfonic acid solution; specifically, it is prepared by curing a tetrahydroxycalix[4]arylenetetrasulfonic acid solution on a support layer. The tetrahydroxycalix[4]arylenetetrasulfonic acid solution comprises tetrahydroxycalix[4]arylenetetrasulfonic acid, glycerol, and water. Specifically, the tetrahydroxycalix[4]arylenetetrasulfonic acid solution is composed of tetrahydroxycalix[4]arylenetetrasulfonic acid, glycerol, and water. In the tetrahydroxycalix[4]arylenetetrasulfonic acid solution, the mass content of tetrahydroxycalix[4]arylenetetrasulfonic acid is 0.1%~2.0%, for example, 0.1%~1.5%; the mass content of glycerol is 1%~3%, for example, 1.5%~2.5%.

[0039] The present invention does not impose any particular limitation on the thickness of the functional layer. In some embodiments of the present invention, the thickness of the functional layer is 0.01~1 μm, for example 0.02 μm.

[0040] In this invention, the polyamide separation layer is formed by an interfacial polymerization reaction between an aqueous solution and an oil solution on a functional layer.

[0041] In some embodiments of the present invention, the aqueous solution comprises an amine monomer, a surfactant, a polar solvent, an acid absorbent, and water. The mass ratio of the amine monomer, surfactant, polar solvent, and water is 1~5:0.1~0.5:1~5:89.5~97.9, for example, 22:2:20:954 (i.e., 2.2:0.2:2:95.4). The acid absorbent is used to adjust the pH value of the aqueous solution. The pH value of the aqueous solution is 7.0~8.0, for example, 7.5~8.0.

[0042] In some embodiments of the present invention, the amine monomer is m-phenylenediamine. The surfactant is sodium dodecylbenzenesulfonate. The polar solvent is N-methylpyrrolidone. The acid absorbent is sodium hydroxide.

[0043] The present invention does not impose any special limitations on the preparation method of the aqueous solution. In some embodiments of the present invention, the preparation method of the aqueous solution includes the following steps: stirring and mixing amine monomers, surfactants, polar solvents, acid absorbents and water to obtain an aqueous solution.

[0044] In some embodiments of the present invention, the oil phase solution is composed of an acyl chloride monomer and an oil phase solvent. The acyl chloride monomer is trimesoyl chloride, and the oil phase solvent is Isopar G. In the oil phase solution, the mass content of the acyl chloride monomer is 0.05% to 0.5%, for example, 0.3%.

[0045] The present invention does not impose any special limitations on the preparation method of the oil phase solution. In some embodiments of the present invention, the preparation method of the oil phase solution includes the following steps: stirring and mixing the acyl chloride monomer and the oil phase solvent to obtain the oil phase solution.

[0046] In some embodiments of the present invention, the thickness of the polyamide separation layer is 0.1~0.5 μm, for example 0.3 μm.

[0047] This invention also provides a method for preparing the seawater desalination reverse osmosis membrane described above, comprising the following steps:

[0048] A. The casting solution is coated onto one side of the nonwoven fabric layer and cured into a film by phase inversion to obtain a base film; the base film includes a nonwoven fabric layer and a support layer formed on the nonwoven fabric layer;

[0049] B. A tetrahydroxycalix[4] aromatic tetrasulfonic acid solution is coated on one side of the support layer of the base film. After curing, a functional layer is formed.

[0050] C. Coat the functional layer with an aqueous solution, remove and allow it to dry slightly, then coat it with an oil solution. After heat curing, a polyamide separation layer is formed, resulting in a seawater desalination reverse osmosis membrane.

[0051] Regarding step A:

[0052] In some embodiments of the present invention, the phase transformation curing temperature is 20~40℃, for example 25℃; the time is 1~10 min, for example 2 min. The phase transformation curing is carried out in deionized water. After the phase transformation curing, the process further includes rinsing with deionized water.

[0053] Regarding step B:

[0054] In some embodiments of the present invention, the tetrahydroxycalix[4]arylenetetrasulfonic acid solution comprises tetrahydroxycalix[4]arylenetetrasulfonic acid, glycerol, and water. Specifically, the tetrahydroxycalix[4]arylenetetrasulfonic acid solution is composed of tetrahydroxycalix[4]arylenetetrasulfonic acid, glycerol, and water. In the tetrahydroxycalix[4]arylenetetrasulfonic acid solution, the mass content of tetrahydroxycalix[4]arylenetetrasulfonic acid is 0.1% to 1.5%; the mass content of glycerol is 1.5% to 2.5%.

[0055] In some embodiments of the present invention, the preparation method of the tetrahydroxycalix[4] aromatic tetrasulfonic acid solution is as follows:

[0056] Tetrahydroxycalix[4]arenetetrasulfonic acid was dissolved in water and mixed with glycerol to obtain a tetrahydroxycalix[4]arenetetrasulfonic acid solution.

[0057] In some embodiments of the present invention, after coating the support layer side of the base film with a tetrahydroxycalix[4] aromatic tetrasulfonic acid solution, the method further includes: draining off excess solution.

[0058] In some embodiments of the present invention, the curing method is drying. The drying temperature is 35~45°C, for example 40°C; the drying time is 2~4 min, for example 3 min.

[0059] Regarding step C:

[0060] The present invention does not impose any special restrictions on the amount of aqueous solution coated on the functional layer; generally, it allows for excessive coating.

[0061] In some embodiments of the present invention, the surface drying method is as follows:

[0062] Use a low-pressure air knife to remove excess solution from the surface of the functional layer.

[0063] In this invention, the oil phase solution is applied to the side of the functional layer coated with the aqueous phase solution.

[0064] The present invention does not impose any special restrictions on the amount of coating of the oil phase solution; generally, it allows for excessive coating.

[0065] In some embodiments of the present invention, after further coating with the oil phase solution, the process includes surface drying. The surface drying method is to remove excess solution from the surface of the functional layer using a low-pressure air knife.

[0066] The thermosetting process is also a process in which the aqueous solution and the oil solution undergo an interfacial polymerization reaction on the functional layer. In some embodiments of the present invention, the temperature of the thermosetting process is 70~90℃, for example 80℃; and the time is 3~7 min, for example 5 min.

[0067] The present invention does not impose any special restrictions on the source of the raw materials used above, and they can be commercially available.

[0068] This invention utilizes the hydrogen bonding force between tetrahydroxycalix[4]arenetetrasulfonic acid and polysulfone to fix tetrahydroxycalix[4]arenetetrasulfonic acid on the surface of polysulfone for the first time. Then, through interfacial polymerization, the "cup-shaped" polymer tetrahydroxycalix[4]arenetetrasulfonic acid is embedded into the polyamide layer of the seawater desalination reverse osmosis membrane, constructing "cup-shaped" nanochannels in the polyamide layer to improve the flux of the seawater membrane. Furthermore, because the tetrahydroxycalix[4]arenetetrasulfonic acid embedded in the polyamide layer contains phenolic hydroxyl groups, the hydrophilicity of the seawater membrane polyamide layer is improved, and the corresponding membrane flux is improved. At the same time, due to the presence of sulfonic acid groups in the tetrahydroxycalix[4]arenetetrasulfonic acid, the charge on the surface of the seawater membrane is enhanced, and the desalination rate of the seawater membrane is improved under the action of the charge effect.

[0069] The seawater desalination reverse osmosis membrane prepared by this invention breaks the traditional trade-off balance of reverse osmosis membranes, achieving a dual improvement in membrane water flux and desalination rate. Furthermore, the process is very simple to operate and easily scaled up for production.

[0070] To further illustrate the present invention, the following detailed description of a seawater desalination reverse osmosis membrane and its preparation method provided by the present invention is provided in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0071] Example 1

[0072] 1. Preparation of casting solution: Add 840g of DMF solvent and 160g of polysulfone to a beaker, stir at 75℃ until dissolved to form a homogeneous solution, and let stand for 24 h to remove bubbles to obtain the casting solution.

[0073] 2. Preparation of tetrahydroxycalix[4]arenetetrasulfonic acid solution: Dissolve 2g of tetrahydroxycalix[4]arenetetrasulfonic acid in 978g of water and mix with 20g of glycerol to obtain tetrahydroxycalix[4]arenetetrasulfonic acid solution.

[0074] 3. Preparation of aqueous solution: Mix 22g m-phenylenediamine, 2g sodium dodecylbenzenesulfonate, 20g N-methylpyrrolidone and 954g water thoroughly, and adjust the pH to 8.0 with sodium hydroxide to obtain an aqueous solution.

[0075] 4. Preparation of oil phase solution: Dissolve 3g of trimesoyl chloride in 997g of Isopar G, stir well to obtain oil phase solution.

[0076] 5. Preparation of seawater desalination reverse osmosis membrane: The casting solution is coated onto a nonwoven fabric layer (thickness 100 μm, air permeability 1.5 cc / cm). 2 The single-sided surface of the membrane was immersed in deionized water at 25°C for phase inversion and curing for 2 min. After washing with deionized water, a support layer (thickness 150 μm) was formed, and a polysulfone-based membrane was obtained. A tetrahydroxycalix[4]arene tetrasulfonic acid solution was coated on one side of the support layer of the polysulfone-based membrane. After curing, a functional layer (thickness 0.02 μm) was formed. Then an aqueous solution was coated on the functional layer. After removing the excess solution on the surface with a low-pressure air knife, an oil solution was coated on it. After removing the excess solution on the surface of the functional layer with a low-pressure air knife, it was then heat-cured in an oven at 80°C for 5 min to form a polyamide separation layer (thickness 0.3 μm), and a seawater desalination reverse osmosis membrane was obtained.

[0077] Example 2

[0078] The difference from Example 1 is as follows:

[0079] 2. Preparation of tetrahydroxycalix[4] aryl tetrasulfonic acid solution: Dissolve 5g of tetrahydroxycalix[4] aryl tetrasulfonic acid in 975g of water and mix with 20g of glycerol to obtain tetrahydroxycalix[4] aryl tetrasulfonic acid solution.

[0080] The remaining steps are the same as in Example 1, and a seawater desalination reverse osmosis membrane is obtained.

[0081] Example 3

[0082] The difference from Example 1 is as follows:

[0083] 2. Preparation of tetrahydroxycalix[4]arenetetrasulfonic acid solution: Dissolve 8g of tetrahydroxycalix[4]arenetetrasulfonic acid in 972g of water and mix with 20g of glycerol to obtain tetrahydroxycalix[4]arenetetrasulfonic acid solution.

[0084] The remaining steps are the same as in Example 1, and a seawater desalination reverse osmosis membrane is obtained.

[0085] Example 4

[0086] The difference from Example 1 is as follows:

[0087] 2. Preparation of tetrahydroxycalix[4] aryl tetrasulfonic acid solution: Dissolve 12g of tetrahydroxycalix[4] aryl tetrasulfonic acid in 968g of water and mix with 20g of glycerol to obtain tetrahydroxycalix[4] aryl tetrasulfonic acid solution.

[0088] The remaining steps are the same as in Example 1, and a seawater desalination reverse osmosis membrane is obtained.

[0089] Example 5

[0090] The difference from Example 1 is as follows:

[0091] 2. Preparation of tetrahydroxycalix[4]arenetetrasulfonic acid solution: Dissolve 15g of tetrahydroxycalix[4]arenetetrasulfonic acid in 965g of water and mix with 20g of glycerol to obtain tetrahydroxycalix[4]arenetetrasulfonic acid solution.

[0092] The remaining steps are the same as in Example 1, and a seawater desalination reverse osmosis membrane is obtained.

[0093] Example 6

[0094] The difference from Example 3 is as follows:

[0095] 1. Preparation of casting solution: Add 860g of DMF solvent and 140g of polysulfone to a beaker, stir at 75℃ until dissolved to form a homogeneous solution, and let stand for 24 h to remove bubbles to obtain the casting solution.

[0096] The remaining steps are the same as in Example 3, and a seawater desalination reverse osmosis membrane is obtained.

[0097] Example 7

[0098] The difference from Example 3 is as follows:

[0099] 1. Preparation of casting solution: Add 820g of DMF solvent and 180g of polysulfone to a beaker, stir at 75℃ until dissolved to form a homogeneous solution, and let stand for 24 h to remove bubbles to obtain the casting solution.

[0100] The remaining steps are the same as in Example 3, and a seawater desalination reverse osmosis membrane is obtained.

[0101] Comparative Example 1

[0102] 1. Preparation of casting solution: Same as in Example 1.

[0103] 2. Preparation of aqueous solution: Same as in Example 1.

[0104] 3. Preparation of oil phase solution: Same as in Example 1.

[0105] 4. Preparation of seawater desalination reverse osmosis membrane: The casting solution is coated onto a nonwoven fabric layer (thickness 100 μm, air permeability 1.5 cc / cm). 2A single-sided surface of the membrane (with a diameter of 100 μm) is immersed in deionized water at 25°C for phase inversion and curing for 2 min. After rinsing with deionized water, a support layer (150 μm thick) is formed, resulting in a polysulfone-based membrane. An aqueous solution is then coated onto the polysulfone-based membrane. Excess solution on the surface is removed using a low-pressure air knife. An oil-phase solution is then coated on top, and excess solution on the functional layer surface is removed using a low-pressure air knife. Finally, the membrane is heat-cured in an 80°C oven for 5 min to form a polyamide separation layer, resulting in a seawater desalination reverse osmosis membrane.

[0106] Comparative Example 2

[0107] 1. Preparation of casting solution: Same as in Example 3.

[0108] 2. Preparation of aqueous solution: Same as in Example 3.

[0109] 3. Preparation of oil phase solution: Dissolve 8g of calixarane acyl chloride derivative II1 (m=5) (this substance is insoluble in water) from Example 2 of patent application document CN103272486A in 992g of Isopar G, and stir evenly to obtain oil phase solution.

[0110] 4. Preparation of seawater desalination reverse osmosis membrane: The casting solution is coated onto a nonwoven fabric layer (thickness 100 μm, air permeability 1.5 cc / cm). 2 A single-sided surface of the membrane (with a diameter of 100 μm) is immersed in deionized water at 25°C for phase inversion and curing for 2 min. After rinsing with deionized water, a support layer (150 μm thick) is formed, resulting in a polysulfone-based membrane. An aqueous solution is then coated onto the polysulfone-based membrane. Excess solution on the surface is removed using a low-pressure air knife. An oil-phase solution is then coated on top, and excess solution on the functional layer surface is removed using a low-pressure air knife. Finally, the membrane is heat-cured in an 80°C oven for 5 min to form a polyamide separation layer, resulting in a seawater desalination reverse osmosis membrane.

[0111] Comparative Example 3

[0112] 1. Preparation of casting solution: Same as in Example 3.

[0113] 2. Preparation of aqueous solution: Same as in Example 3.

[0114] 3. Preparation of oil phase solution: Dissolve 8g of calixarane acyl chloride derivative II2 (m=4) (this substance is insoluble in water) from Example 5 of patent application document CN103272486A in 992g of Isopar G, and stir evenly to obtain oil phase solution.

[0115] 4. Preparation of seawater desalination reverse osmosis membrane: The casting solution is coated onto a nonwoven fabric layer (thickness 100 μm, air permeability 1.5 cc / cm). 2A single-sided surface of the membrane (with a diameter of 100 μm) is immersed in deionized water at 25°C for phase inversion and curing for 2 min. After rinsing with deionized water, a support layer (150 μm thick) is formed, resulting in a polysulfone-based membrane. An aqueous solution is then coated onto the polysulfone-based membrane. Excess solution on the surface is removed using a low-pressure air knife. An oil-phase solution is then coated on top, and excess solution on the functional layer surface is removed using a low-pressure air knife. Finally, the membrane is heat-cured in an 80°C oven for 5 min to form a polyamide separation layer, resulting in a seawater desalination reverse osmosis membrane.

[0116] Comparative Example 4

[0117] 1. Preparation of casting solution: Same as in Example 7.

[0118] 2. Replace the tetrahydroxycalix[4] aromatic tetrasulfonic acid solution with the resorcinol calix[4] aromatic (R=-CH2CH2CH3) solution in Example 1 of patent application CN113663529A:

[0119] Preparation of resorcinol calix[4]arene (R=-CH2CH2CH3) solution: Dissolve 8g of resorcinol calix[4]arene (R=-CH2CH2CH3) (this substance is insoluble in water) in 972g of ethanol, mix with 20g of glycerol to obtain resorcinol calix[4]arene (R=-CH2CH2CH3) solution.

[0120] 3. Preparation of aqueous solution: Same as in Example 7.

[0121] 4. Preparation of oil phase solution: Same as in Example 7.

[0122] 5. Preparation of seawater desalination reverse osmosis membrane: The casting solution is coated onto a nonwoven fabric layer (thickness 100 μm, air permeability 1.5 cc / cm). 2 The single-sided surface of the membrane was immersed in deionized water at 25°C for phase inversion and curing for 2 min. After washing with deionized water, a support layer (thickness 150 μm) was formed, and a polysulfone-based membrane was obtained. A resorcinol calix[4] aromatic hydrocarbon (R=-CH2CH2CH3) solution was coated on one side of the support layer of the polysulfone-based membrane. After curing, a functional layer (thickness 0.02 μm) was formed. Then an aqueous phase solution was coated on the functional layer. After removing the excess solution on the surface with a low-pressure air knife, an oil phase solution was coated on it. After removing the excess solution on the surface of the functional layer with a low-pressure air knife, it was then heat-cured in an oven at 80°C for 5 min to form a polyamide separation layer (thickness 0.3 μm), and a seawater desalination reverse osmosis membrane was obtained.

[0123] Comparative Example 5

[0124] The difference from Example 7 is as follows:

[0125] 1. Preparation of casting solution: Add 820g of DMF solvent and 180g of polyethersulfone to a beaker, stir at 75℃ until dissolved to form a homogeneous solution, and let stand for 24 h to remove bubbles to obtain the casting solution.

[0126] The remaining steps are the same as in Example 7, and a seawater desalination reverse osmosis membrane is obtained.

[0127] The seawater desalination reverse osmosis membranes of the above comparative examples and embodiments were subjected to performance testing using a 32,000 ppm sodium chloride solution at 5.51 MPa and 25°C. The test results are shown in Table 1.

[0128] Table 1. Performance test results of seawater desalination reverse osmosis membranes obtained from comparative examples and embodiments.

[0129]

[0130] The descriptions of the above embodiments are merely illustrative of the methods and core ideas of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A seawater desalination reverse osmosis membrane, characterized in that, It includes a nonwoven fabric layer, a support layer, a functional layer, and a polyamide release layer that are in contact with each other in sequence; The functional layer is composed of cup-shaped polymer tetrahydroxycalix[4] aromatic tetrasulfonic acid.

2. The seawater desalination reverse osmosis membrane according to claim 1, characterized in that, The functional layer was prepared by curing a tetrahydroxycalix[4] aromatic tetrasulfonic acid solution; The tetrahydroxycalix[4] aryl tetrasulfonic acid solution comprises tetrahydroxycalix[4] aryl tetrasulfonic acid, glycerol and water.

3. The seawater desalination reverse osmosis membrane according to claim 2, characterized in that, In the tetrahydroxycalix[4]arenetetrasulfonic acid solution, the mass content of tetrahydroxycalix[4]arenetetrasulfonic acid is 0.1%~2.0%; the mass content of glycerol is 1%~3%.

4. The seawater desalination reverse osmosis membrane according to claim 1, characterized in that, The polyamide separation layer is formed by interfacial polymerization of an aqueous solution and an oil solution on a functional layer; The aqueous solution comprises amine monomers, surfactants, polar solvents, acid absorbents, and water; The oil phase solution comprises an acyl chloride monomer and an oil phase solvent.

5. The seawater desalination reverse osmosis membrane according to claim 4, characterized in that, The mass ratio of the amine monomer, surfactant, polar solvent, and water is 1~5:0.1~0.5:1~5:89.5~97.9; The acid absorbent is used to adjust the pH value of the aqueous solution; the pH value of the aqueous solution is 7.0~8.

0.

6. The seawater desalination reverse osmosis membrane according to claim 4, characterized in that, The amine monomer is m-phenylenediamine; the surfactant is sodium dodecylbenzenesulfonate; the polar solvent is N-methylpyrrolidone; and the acid absorbent is sodium hydroxide.

7. The seawater desalination reverse osmosis membrane according to claim 4, characterized in that, The acyl chloride monomer is pyromellitic trimethylol chloride; the oil phase solvent is Isopar G; The mass content of acyl chloride monomer in the oil phase solution is 0.05%~0.5%.

8. A method for preparing a seawater desalination reverse osmosis membrane according to any one of claims 1 to 7, characterized in that, Includes the following steps: A. The casting solution is coated onto one side of the nonwoven fabric layer and cured into a film by phase inversion to obtain a base film; the base film includes a nonwoven fabric layer and a support layer formed on the nonwoven fabric layer; B. A tetrahydroxycalix[4] aromatic tetrasulfonic acid solution is coated on one side of the support layer of the base film. After curing, a functional layer is formed. C. Coat the functional layer with an aqueous solution, remove and allow it to dry slightly, then coat it with an oil solution. After heat curing, a polyamide separation layer is formed, resulting in a seawater desalination reverse osmosis membrane.

9. The preparation method according to claim 8, characterized in that, In step C, the temperature of the thermosetting treatment is 70~90℃ and the time is 3~7 min.

10. The preparation method according to claim 8, characterized in that, In step A, the phase transformation curing temperature is 20~40℃ and the time is 1~10 min.

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