Preparation method of reverse osmosis basement membrane capable of being quickly dissolved out, reverse osmosis basement membrane prepared by preparation method and application of reverse osmosis basement membrane

Abstract

The invention provides a preparation method of a quick-dissolution reverse osmosis basement membrane, the reverse osmosis basement membrane prepared by the preparation method and application, and relates to the technical field of reverse osmosis basement membrane preparation. The preparation method comprises the following steps: mixing a pre-casting membrane solution containing polysulfone and a solution containing an amphiphilic block copolymer to obtain a casting membrane solution; coating the surface of a base material with the casting film solution to obtain the base material with a wet film layer; immersing the base material with the wet film layer into a coagulating bath, and obtaining a base film with a modified polysulfone layer through a non-solvent induced phase transformation method; sequentially contacting the base membrane with the modified polysulfone layer with a water-phase monomer solution containing m-phenylenediamine and an oil-phase monomer solution containing trimesoyl chloride, and curing to form a polyamide layer, so as to obtain the reverse osmosis base membrane capable of being quickly dissolved out. The TOC dissolution amount of the reverse osmosis membrane material can be effectively reduced, the TOC dissolution process is accelerated, it is ensured that the membrane can rapidly reach the preset water quality standard in the initial use stage, and the performance stability of the membrane is improved.

Description

Technical Field

[0001] The invention relates to the technical field of reverse osmosis base membrane preparation, and in particular to a method for preparing a fast-dissolving reverse osmosis base membrane, and the reverse osmosis base membrane prepared thereby and its application. Background Art

[0002] In the field of pharmaceutical and electronic grade ultrapure water, there are strict requirements for the TOC content in water. The US ASTM D5127-09 and the national standard "Electronic Grade Water GB / T 11446.1-1997" clearly stipulate the water quality requirements for pure water used in the electronic grade semiconductor industry. According to the TOC content in the water, different water use levels are clearly divided. Reverse osmosis (RO) elements can efficiently remove soluble impurities, ions, organic matter, microorganisms, etc. in water. The RO system can provide high-quality water sources for subsequent treatment processes and ensure the final ultrapure water quality. It not only ensures the strict requirements for water quality in the manufacturing process, but also reduces the burden of subsequent treatment, ensures the stability of the production process, and reduces equipment wear and maintenance costs. Reverse osmosis technology has become an indispensable core link in the ultrapure water preparation process.

[0003] At present, the mainstream reverse osmosis membrane is a composite membrane, which is composed of a polysulfone support layer (base membrane) and an ultra-thin polyamide functional layer. Although there are a large number of reverse osmosis manufacturers at home and abroad, they all add organic matter to modify the membrane or ensure the preservation performance of the membrane before it is put into operation during the production process. Therefore, the base membrane carries a large amount of organic matter. In the initial stage of operation and commissioning and in the actual use process, the membrane itself will produce a large amount of TOC. Due to the characteristics of the membrane itself, the interaction between TOC and it has an important influence on its dissolution rate; in addition, the base membrane itself is a porous structure, and the pore structure also has an important influence on the dissolution efficiency and continuous dissolution of TOC. This leads to the need for a large amount of water and energy to repeatedly rinse the TOC of the membrane itself before installation to avoid affecting the normal operation of the system.

[0004] In summary, the shortcomings of the existing reverse osmosis membranes mainly include: 1. During the preparation process or in the use process, a high amount of TOC is easily released from the membrane surface. Especially when a new membrane is put into use, the TOC dissolution phenomenon is more obvious, resulting in heavy water pollution in the initial stage, affecting the stability of the process; 2. Although some existing membrane materials have a certain TOC dissolution control ability, due to the slow dissolution rate, they cannot effectively reduce the dissolved substances in a short time, resulting in a longer "membrane washing" process or pretreatment link in the early stage of membrane use, which increases production costs and time.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a fast-dissolving reverse osmosis base membrane, a reverse osmosis base membrane prepared by the method, and applications. The reverse osmosis base membrane of the present invention has a membrane structure with a larger surface area and optimized pore distribution, which improves the dissolution efficiency of the membrane and ensures that the membrane releases the required substances uniformly and quickly during the dissolution process. The reverse osmosis membrane prepared on the basis of the base membrane greatly improves the dissolution rate of TOC.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] In a first aspect, the present invention provides a method for preparing a fast-dissolving reverse osmosis base membrane, the preparation method comprising:

[0009] Mixing a precasting solution containing polysulfone and a solution containing an amphiphilic block copolymer to obtain a casting solution;

[0010] The casting solution is applied to the surface of a substrate to obtain a substrate having a wet film layer; the substrate having the wet film layer is immersed in a coagulation bath to obtain a base film having a modified polysulfone layer by a non-solvent induced phase transition method;

[0011] The base membrane with the modified polysulfone layer is sequentially contacted with an aqueous monomer solution containing m-phenylenediamine and an oily monomer solution containing trimesoyl chloride, and then solidified to form a polyamide layer, thereby obtaining the fast-dissolving reverse osmosis base membrane.

[0012] Preferably, the mass ratio of the polysulfone to the amphiphilic block copolymer is (12-20):(0.001-10).

[0013] Preferably, the casting solution comprises, by mass percentage, 12-20% polysulfone and 0.001-10% amphiphilic block copolymer, with the remainder being a mixed solvent.

[0014] Preferably, the structure of the amphiphilic block copolymer includes any one or a combination of at least two of an AB type copolymer, an ABA type copolymer or an ABC type copolymer;

[0015] Wherein, the polymer segments A, B, and C are each independently selected from any one of polyacrylic acid, polyacrylamide, polyethylene oxide, poly-4-vinylpyridine, polyglycidyl acrylate, poly-N-isopropylacrylamide, polystyrene, polymethyl methacrylate, polybenzyl methacrylate, poly-4-hydroxymethylstyrene, or polyhexafluorobutyl methacrylate, and the polymer segments A, B, and C have at least one hydrophilic segment and one hydrophobic segment.

[0016] Preferably, the molecular weight of the polysulfone is 10,000 to 100,000 Da.

[0017] Preferably, the molecular weight of the amphiphilic block copolymer is 2000-50000 Da.

[0018] Preferably, the step of configuring the precast membrane solution containing polysulfone comprises:

[0019] The polysulfone is dissolved in an organic solvent, heated and stirred, and vacuum degassing is performed to obtain the polysulfone-containing precast membrane solution.

[0020] Preferably, the heating and stirring temperature is 50 to 70° C., and the heating and stirring time is 12 to 24 hours.

[0021] Preferably, the polysulfone-containing precast membrane solution comprises, by weight percentage, 10-20% polysulfone and the remainder being an organic solvent.

[0022] Preferably, the organic solvent includes any one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone, or a combination of at least two thereof.

[0023] Preferably, the step of preparing the solution containing the amphiphilic block copolymer comprises:

[0024] The amphiphilic block copolymer is dissolved in a good solvent, and a poor solvent is added dropwise for self-assembly to form nanoparticles of the amphiphilic block copolymer. A mixed solvent of a good solvent and a poor solvent is then added for stirring and dilution to obtain the solution containing the amphiphilic block copolymer.

[0025] Preferably, the good solvent includes any one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone, or a combination of at least two thereof.

[0026] Preferably, the poor solvent includes any one of water, methanol, ethanol or acetone, or a combination of at least two of them.

[0027] Preferably, the mass ratio of the amphiphilic block copolymer, the good solvent, the poor solvent, the mixed solvent and the precast membrane solution is 1:(1-20):(1-20):(1-200):(100-500).

[0028] Preferably, in the mixed solvent, the mass ratio of the good solvent to the poor solvent is (10-90):(10-90).

[0029] Preferably, the temperature for self-assembly by dripping a poor solvent is 10 to 40° C., and the time for self-assembly is 0.5 to 2 hours.

[0030] Preferably, the stirring and dilution temperature is 10-40° C., and the stirring and dilution time is 0.5-2 h.

[0031] Preferably, the substrate comprises a nonwoven fabric.

[0032] Preferably, the coagulation bath comprises any one or a combination of at least two of water, methanol, ethanol, acetone, N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone;

[0033] Preferably, the temperature of the coagulation bath is 20-60°C.

[0034] Preferably, the thickness of the modified polysulfone layer is 20-50 μm.

[0035] Preferably, the aqueous monomer solution containing m-phenylenediamine comprises, by mass percentage, 0.5-4% m-phenylenediamine and the remainder being an aqueous solvent.

[0036] Preferably, the oil phase monomer solution containing trimesoyl chloride comprises, by mass percentage, 0.01-0.3% trimesoyl chloride and the remainder being oil phase solvent.

[0037] Preferably, the aqueous solvent comprises water.

[0038] Preferably, the aqueous phase solvent further comprises any one of dimethyl sulfoxide, methanol or isopropanol, or a combination of at least two thereof.

[0039] Preferably, the oil phase solvent includes any one of hexane, heptane or isoparaffin, or a combination of at least two of them.

[0040] Preferably, the curing temperature is 70-100° C., and the curing time is 2-60 min.

[0041] Preferably, the thickness of the polyamide layer is 100-500 nm.

[0042] In a second aspect, the present invention provides a reverse osmosis base membrane, which is prepared by the preparation method described in the first aspect.

[0043] Preferably, the reverse osmosis base membrane comprises a non-woven fabric layer, a modified polysulfone composite layer, and a polyamide layer stacked in sequence.

[0044] Preferably, the pore size of the reverse osmosis base membrane is 10 to 400 nm.

[0045] Preferably, the pore size distribution parameters of the reverse osmosis base membrane include: the pore volume of pores with a pore size of 200 to 250 nm accounts for 80 to 100% of the total pore volume.

[0046] Preferably, the TOC dissolution amount of the reverse osmosis base membrane is 0.1 to 20 ppm / dm 2The TOC dissolution rate of the reverse osmosis base membrane is 0.003-1 ppm / dm 2 / min.

[0047] Preferably, the flux of the reverse osmosis base membrane is above 58LMH.

[0048] Preferably, the desalination rate of the reverse osmosis base membrane is above 99%.

[0049] In a third aspect, the present invention provides a use of the reverse osmosis base membrane as described in the second aspect in preparing ultrapure water.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) In the present invention, by adding an amphiphilic block copolymer during the preparation of the base membrane, the pore structure of the base membrane is more uniform. After the reverse osmosis membrane is prepared, TOC can be efficiently dissolved, the dissolution rate of TOC is significantly improved, and there is no continuous dissolution.

[0052] (2) The amphiphilic block copolymer improves the hydrophilicity of the base membrane, which improves the cleaning effect during the preparation of the reverse osmosis membrane and can effectively reduce the initial TOC dissolution of the reverse osmosis membrane material to ensure that the predetermined water quality standards can be quickly reached in the early stage of membrane use, thereby improving the performance stability of the membrane and reducing adverse effects in the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 This is the pore size distribution diagram of the reverse osmosis base membrane provided in Example 3.

[0055] Figure 2 This is the pore size distribution diagram of the reverse osmosis base membrane provided for Comparative Example 1.

[0056] Figure 3 This is a comparison chart of TOC dissolution of the reverse osmosis base membranes provided in Examples 1 to 7 and the reverse osmosis base membranes provided in Comparative Examples 1 to 3. DETAILED DESCRIPTION

[0057] Unless otherwise defined herein, scientific and technological terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0058] It should be noted that specific details are described in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in a variety of other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0059] The embodiments of the present invention will be described in detail below in conjunction with the embodiments and examples, but it will be appreciated by those skilled in the art that the following embodiments and examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified, proceed according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0060] In a first aspect, the present invention provides a method for preparing a fast-dissolving reverse osmosis base membrane, the preparation method comprising:

[0061] Mixing a precasting solution containing polysulfone and a solution containing an amphiphilic block copolymer to obtain a casting solution;

[0062] The casting solution is applied to the surface of a substrate to obtain a substrate having a wet film layer; the substrate having the wet film layer is immersed in a coagulation bath to obtain a base film having a modified polysulfone layer by a non-solvent induced phase transition method;

[0063] The base membrane with the modified polysulfone layer is sequentially contacted with an aqueous monomer solution containing m-phenylenediamine and an oily monomer solution containing trimesoyl chloride, and then solidified to form a polyamide layer, thereby obtaining the fast-dissolving reverse osmosis base membrane.

[0064] In the present invention, by adding an amphiphilic block copolymer during the preparation of the base membrane, the pore structure of the prepared base membrane is more uniform, and after the reverse osmosis membrane is prepared, TOC is efficiently dissolved without continuous dissolution. The amphiphilic block copolymer improves the hydrophilicity of the base membrane, and the cleaning effect is better during the preparation of the reverse osmosis membrane, and the initial TOC dissolution is lower.

[0065] As an optional embodiment, the mass ratio of the polysulfone and the amphiphilic block copolymer is (12-20):(0.001-10); wherein, "12-20" can be, for example, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc.; wherein, "0.001-10" can be, for example, 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

[0066] As an optional implementation, the casting solution comprises, by mass percentage, 12-20% polysulfone and 0.001-10% amphiphilic block copolymer, with the remainder being a mixed solvent.

[0067] As a preferred embodiment, based on the total mass of the casting solution as 100%, the content of polysulfone is 12-20%, for example, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0068] As a preferred embodiment, based on the total mass of the casting solution as 100%, the content of the amphiphilic block copolymer is 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0069] As an optional embodiment, the mixed solvent in the casting solution includes solvent A in the precasting solution containing polysulfone, and solvent B in the solution containing the amphiphilic block copolymer. More specifically, the solvent A includes any one or a combination of at least two of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone; the solvent B includes a good solvent and a poor solvent, the good solvent includes any one or a combination of at least two of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone, and the poor solvent includes any one or a combination of at least two of water, methanol, ethanol or acetone.

[0070] As an optional embodiment, the structure of the amphiphilic block copolymer includes any one or a combination of at least two of an AB type copolymer, an ABA type copolymer or an ABC type copolymer;

[0071] Wherein, the polymer segments A, B, and C are each independently selected from any one of polyacrylic acid, polyacrylamide, polyethylene oxide, poly-4-vinylpyridine, polyglycidyl acrylate, poly-N-isopropylacrylamide, polystyrene, polymethyl methacrylate, polybenzyl methacrylate, poly-4-hydroxymethylstyrene, or polyhexafluorobutyl methacrylate, and the polymer segments A, B, and C have at least one hydrophilic segment and one hydrophobic segment.

[0072] It should be noted that the hydrophilic segment in the above polymer segment includes any one of polyacrylic acid, polyacrylamide, poly-4-vinylpyridine, polyglycidyl acrylate or polyethylene oxide.

[0073] It should be noted that the hydrophobic segment in the above polymer segment includes any one of polystyrene, polymethyl methacrylate, polybenzyl methacrylate, poly-4-hydroxymethylstyrene or polyhexafluorobutyl methacrylate.

[0074] It should be noted that the poly-N-isopropylacrylamide in the above polymer chain segment shows hydrophilicity at low temperatures and shows hydrophobicity at high temperatures.

[0075] As a preferred embodiment, the amphiphilic block copolymer includes any one of polyacrylic acid-polymethyl methacrylate, polyethylene oxide-polybenzyl methacrylate-polyethylene oxide or polyacrylamide-poly (4-hydroxymethyl)styrene or a combination of at least two thereof.

[0076] As a preferred embodiment, the molecular weight of the polysulfone is 10000-100000 Da, for example, it can be 10000 Da, 20000 Da, 30000 Da, 40000 Da, 50000 Da, 60000 Da, 70000 Da, 80000 Da, 90000 Da, 100000 Da, etc.

[0077] As a preferred embodiment, the molecular weight of the amphiphilic block copolymer is 2000-50000Da, for example, it can be 2000Da, 3000Da, 4000Da, 5000Da, 6000Da, 7000Da, 8000Da, 9000Da, 10000Da, 15000Da, 20000Da, 25000Da, 30000Da, 35000Da, 40000Da, 45000Da, 50000Da, etc.

[0078] As a preferred embodiment, the steps of configuring the polysulfone-containing precast membrane solution include:

[0079] The polysulfone is dissolved in an organic solvent, heated and stirred, and vacuum degassing is performed to obtain the polysulfone-containing precast membrane solution.

[0080] As a preferred embodiment, the heating and stirring temperature is 50-70°C, for example, it can be 50°C, 52°C, 54°C, 55°C, 56°C, 58°C, 60°C, 62°C, 64°C, 65°C, 68°C, 70°C, etc., and the heating and stirring time is 12-24h, for example, it can be 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, etc.

[0081] As a preferred embodiment, the polysulfone-containing precast membrane solution comprises, by weight percentage, 10-20% polysulfone and the remainder being an organic solvent.

[0082] As a preferred embodiment, based on the total mass of the polysulfone-containing precast membrane liquid as 100%, the content of polysulfone is 10-20%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0083] As a preferred embodiment, in the polysulfone-containing precast membrane solution, the organic solvent includes any one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone, or a combination of at least two thereof.

[0084] As a preferred embodiment, the step of preparing the solution containing the amphiphilic block copolymer comprises:

[0085] The amphiphilic block copolymer is dissolved in a good solvent, and a poor solvent is added dropwise for self-assembly to form nanoparticles of the amphiphilic block copolymer. A mixed solvent of a good solvent and a poor solvent is then added for stirring and dilution to obtain the solution containing the amphiphilic block copolymer.

[0086] It should be noted that the amphiphilic block copolymer is first dissolved in a good solvent, and then a poor solvent is added to form block copolymer nanoparticles through self-assembly, which are then added to the precast membrane solution to form a casting solution, which is immersed in a coagulation bath to prepare a reverse osmosis base membrane through non-solvent induced phase transformation, thereby further making the prepared reverse osmosis membrane have lower TOC dissolution and further improving the rapid dissolution ability of TOC. In addition, adding a mixed solvent of a good solvent and a poor solvent for dilution can prevent the formation of gel when added to the casting solution.

[0087] As a preferred embodiment, the good solvent includes any one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone, or a combination of at least two thereof.

[0088] As a preferred embodiment, the poor solvent includes any one of water, methanol, ethanol or acetone, or a combination of at least two of them.

[0089] As a preferred embodiment, the mass ratio of the amphiphilic block copolymer, the good solvent, the poor solvent, the mixed solvent and the precast membrane solution is 1:(1-20):(1-20):(1-200):(100-500);

[0090] Among them, good solvent: "1-20" can be, for example, 1, 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 20, etc.;

[0091] Among them, poor solvent: "1-20" can be, for example, 1, 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 20, etc.;

[0092] Wherein, mixed solvent: "1-200" can be, for example, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, etc.;

[0093] Among them, the precast membrane solution "100-500" can be, for example, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 220, 240, 250, 260, 280, 300, 320, 340, 350, 360, 380, 400, 420, 440, 450, 460, 480, 500, etc.

[0094] It should be noted that the good solvent in the above ratio refers to the "good solvent" in "dissolving the amphiphilic block copolymer in the good solvent"; the "poor solvent" in the above ratio refers to the "poor solvent" in "self-assembly by dropping the poor solvent"; the "mixed solvent" in the above ratio refers to the "mixed solvent" in "adding a mixed solvent of a good solvent and a poor solvent for stirring and dilution". The mass ratio of the good solvent and the poor solvent in the "mixed solvent" is shown in the following paragraph.

[0095] As a preferred embodiment, in the mixed solvent, the mass ratio of the good solvent to the poor solvent is (10-90):(10-90), for example, it can be 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, etc.

[0096] As a preferred embodiment, the temperature for self-assembly by adding a poor solvent is 10-40°C, for example, it can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, etc., and the time for self-assembly is 0.5-2h, for example, it can be 0.5h, 0.6h, 0.8h, 1h, 1.2h, 1.4h, 1.5h, 1.6h, 2h, etc.

[0097] As a preferred embodiment, the stirring and dilution temperature is 10-40°C, for example, it can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, etc., and the stirring and dilution time is 0.5-2h, for example, it can be 0.5h, 0.6h, 0.8h, 1h, 1.2h, 1.4h, 1.5h, 1.6h, 2h, etc.

[0098] As a preferred embodiment, the substrate comprises non-woven fabric.

[0099] As a preferred embodiment, the coagulation bath comprises any one or a combination of at least two of water, methanol, ethanol, acetone, N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone;

[0100] As a preferred embodiment, the temperature of the coagulation bath is 20-60°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, etc.

[0101] As a preferred embodiment, the thickness of the modified polysulfone layer is 20 to 50 μm, for example, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

[0102] It should be noted that the thickness of the above-mentioned base film is adjusted by coating it on the substrate layer (such as non-woven fabric) and then flattening it with a scraper of a certain thickness. By controlling the thickness of the scraper to be within the range of 20 to 50 μm, the thickness of the prepared base film is also made to reach between 20 and 50 μm.

[0103] As a preferred embodiment, the aqueous monomer solution containing m-phenylenediamine comprises, by weight percentage, 0.5-4% m-phenylenediamine and the remainder being an aqueous solvent.

[0104] As a preferred embodiment, based on the total mass of the aqueous monomer solution containing meta-phenylenediamine as 100%, the content of meta-phenylenediamine is 0.5-4%, for example, it can be 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.5%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, etc.

[0105] As a preferred embodiment, the oil phase monomer solution containing trimesoyl chloride comprises, by weight percentage, 0.01 to 0.3% trimesoyl chloride and the remainder being oil phase solvent.

[0106] As a preferred embodiment, based on the total mass of the oil phase monomer solution containing trimesoyl chloride as 100%, the content of trimesoyl chloride is 0.01-0.3%, for example, it can be 0.01%, 0.02%, 0.04%, 0.05%, 0.06%, 0.08%, 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3% and the like.

[0107] As a preferred embodiment, the aqueous phase solvent includes water.

[0108] As a preferred embodiment, the aqueous phase solvent further comprises any one of dimethyl sulfoxide, methanol or isopropanol, or a combination of at least two thereof.

[0109] As a preferred embodiment, the oil phase solvent includes any one of hexane, heptane or isoparaffin, or a combination of at least two of them.

[0110] As a preferred embodiment, the curing temperature is 70-100°C, for example, it can be 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, etc., and the curing time is 2-60min, for example, it can be 2min, 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, 60min, etc.

[0111] As a preferred embodiment, the thickness of the polyamide layer is 100 to 500 nm, for example, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, etc.

[0112] In a second aspect, the present invention provides a reverse osmosis base membrane, which is prepared by the preparation method described in the first aspect.

[0113] As a preferred embodiment, the reverse osmosis base membrane comprises a non-woven fabric layer, a modified polysulfone layer (the modified polysulfone layer is a composite layer of polysulfone and an amphiphilic block copolymer), and a polyamide layer which are stacked in sequence.

[0114] As a preferred embodiment, the pore size of the reverse osmosis base membrane is 10 to 400 nm, for example, it can be 10 nm, 50 nm, 100 nm, 120 nm, 140 nm, 150 nm, 160 nm, 180 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 280 nm, 300 nm, 320 nm, 340 nm, 360 nm, 380 nm, 400 nm, etc.

[0115] As a preferred embodiment, the pore size distribution of the reverse osmosis base membrane includes: the pore volume of pores with a pore size of 200-250 nm accounts for 80-100% of the total pore volume, for example, it can be 80%, 85%, 90%, 95%, 100%, etc.

[0116] As a preferred embodiment, the TOC dissolution amount of the reverse osmosis base membrane is 0.1 to 20 ppm / dm 2 , for example, it can be 0.1ppm / dm 2 、0.5ppm / dm 2 、1ppm / dm 2 、2ppm / dm 2 、3ppm / dm 2 、4ppm / dm 2 、5ppm / dm 2 、6ppm / dm 2 、7ppm / dm 2 、8ppm / dm 2 、9ppm / dm 2 、10ppm / dm 2 、11ppm / dm 2 、12ppm / dm 2 、13ppm / dm 2 、14ppm / dm 2 、15ppm / dm 2 、16ppm / dm 2 、17ppm / dm 2 、18ppm / dm 2 、19ppm / dm 2 、20ppm / dm 2 wait.

[0117] As a preferred embodiment, the TOC dissolution rate of the reverse osmosis base membrane is 0.003 to 1 ppm / dm 2 / min, for example, it can be 0.003ppm / dm 2 / min、0.004ppm / dm 2 / min、0.005ppm / dm2 / min、0.006ppm / dm 2 / min、0.007ppm / dm 2 / min、0.008ppm / dm 2 / min、0.009ppm / dm 2 / min、0.01ppm / dm 2 / min、0.02ppm / dm 2 / min、0.03ppm / dm 2 / min、0.04ppm / dm 2 / min、0.05ppm / dm 2 / min、0.06ppm / dm 2 / min、0.08ppm / dm 2 / min、0.09ppm / dm 2 / min、0.1ppm / dm 2 / min、0.2ppm / dm 2 / min、0.3ppm / dm 2 / min、0.4ppm / dm 2 / min、0.5ppm / dm 2 / min、0.6ppm / dm 2 / min、0.7ppm / dm 2 / min、0.8ppm / dm 2 / min、0.9ppm / dm 2 / min、1ppm / dm 2 / min, etc.

[0118] It should be noted that the dissolution amount here refers to the TOC dissolution amount after the first soaking. "The first soaking" refers to soaking the reverse osmosis base membrane in a pure water solution at 25°C for 30 minutes and then taking it out. The TOC difference between the solution before and after soaking is the TOC dissolution amount. Similarly, repeated soaking with new pure water is the second and third TOC dissolution, and so on. In addition, since the TOC will continue to decrease with subsequent soaking, only the first two TOC dissolution rates are compared: TOC dissolution rate = (TOC dissolution amount of the first time - TOC dissolution amount of the second time) / soaking time.

[0119] As a preferred embodiment, the flux of the reverse osmosis base membrane is above 58LMH, for example, it can be 58LMH, 59LMH, 60LMH, 61LMH, 62LMH, 63LMH, 64LMH, 65LMH, 66LMH, 67LMH, 68LMH, etc.

[0120] As a preferred embodiment, the desalination rate of the reverse osmosis base membrane is above 99%, for example, it can be 99.00%, 99.10%, 99.20%, 99.30%, 99.40%, 99.50%, 99.60%, 99.70%, 99.80%, 99.90%, etc.

[0121] In a third aspect, the present invention provides a use of the reverse osmosis base membrane as described in the second aspect in preparing ultrapure water.

[0122] The present invention is further described below by means of specific examples and comparative examples. However, it should be understood that these examples are only used for more detailed description and should not be construed as limiting the present invention in any form.

[0123] Example 1

[0124] This embodiment provides a method for preparing a fast-dissolving reverse osmosis base membrane, the preparation method comprising the following steps:

[0125] S1. Preparation of casting solution:

[0126] 540 g of polysulfone pellets (molecular weight of 71000 Da) were dissolved in 2260 g of DMF, heated and stirred at 60 ° C for 12 h, and vacuum degassed to obtain a precast membrane liquid containing polysulfone for standby use; 10 g of polyacrylic acid-polymethyl methacrylate (molecular weight of 11000 Da) was dissolved in 90 g of THF, 100 g of water was slowly added dropwise to THF, and stirred for 1 h for self-assembly to form nanoparticles of amphiphilic block copolymers, and then 100 g of a mixed solvent of water and DMF with a mass ratio of 1:1 was added, and stirring was continued for 2 h to obtain the solution containing the amphiphilic block copolymer for standby use; the above-mentioned precast membrane liquid containing polysulfone and the solution containing the amphiphilic block copolymer were mixed to obtain a casting liquid.

[0127] S2. Preparation of base membrane with modified polysulfone layer:

[0128] The casting solution obtained in S1 was coated on a non-woven fabric, flattened with a 35 μm scraper, and then immersed in pure water at 30° C. to obtain a base membrane with a modified polysulfone layer (the thickness of the modified polysulfone layer on the base membrane was 35 μm).

[0129] S3. Preparation of polyamide layer:

[0130] The base membrane with a modified polysulfone layer obtained in S2 is first immersed in a 2wt% m-phenylenediamine solution (the solvent is water) for 1 min, and the excess water phase on the surface is removed with a rubber roller. Then, a 0.1wt% trimesoyl chloride solution (the solvent is hexane) is coated for 1 min, and the excess oil phase on the surface is poured off. The base membrane is placed in a 100°C forced air drying oven for curing for 10 min to form a polyamide layer with a thickness of 200 nm, thereby obtaining the fast-dissolving reverse osmosis base membrane; wherein, the reverse osmosis base membrane includes a non-woven fabric layer, a polysulfone and a polyacrylic acid-polymethyl methacrylate composite layer, and a polyamide layer stacked in sequence.

[0131] Example 2

[0132] This embodiment provides a method for preparing a fast-dissolving reverse osmosis base membrane, the preparation method comprising the following steps:

[0133] S1. Preparation of casting solution:

[0134] 500 g of polysulfone pellets (molecular weight 65000 Da) were dissolved in 2300 g of DMF, heated and stirred at 60° C. for 12 h, and vacuum degassed to obtain a precasting membrane liquid containing polysulfone for later use; 20 g of polyethylene oxide-polybenzyl methacrylate-polyethylene oxide (molecular weight 21300 Da) was dissolved in 80 g of THF, 100 g of water was slowly added dropwise to THF, and stirred for 1 h for self-assembly to form nanoparticles of amphiphilic block copolymers, and then 200 g of a mixed solvent of water and DMF with a mass ratio of 1:1 was added, and stirring was continued for 1 h to obtain the solution containing the amphiphilic block copolymer for later use; the above-mentioned precasting membrane liquid containing polysulfone and the solution containing the amphiphilic block copolymer were mixed to obtain a casting liquid.

[0135] S2. Preparation of base membrane with modified polysulfone layer:

[0136] The casting liquid obtained in S1 was coated on a non-woven fabric, flattened with a 35 μm scraper, and then immersed in a mixed solvent of water and DMF at a mass ratio of 1:4 at 25°C to obtain a base membrane with a modified polysulfone layer (the thickness of the modified polysulfone layer on the base membrane was 35 μm).

[0137] S3. Preparation of polyamide layer:

[0138] The base membrane with a modified polysulfone layer obtained in S2 is first immersed in a 3.5wt% m-phenylenediamine solution (the solvent is water) for 1 minute, and the excess water phase on the surface is removed with a rubber roller. Then, a 0.15wt% trimesoyl chloride solution (the solvent is hexane) is coated for 1 minute, and then the excess oil phase on the surface is poured off. The base membrane is placed in a 100°C forced air drying oven for curing for 30 minutes to form a polyamide layer with a thickness of 250nm, thereby obtaining the fast-dissolving reverse osmosis base membrane; wherein, the reverse osmosis base membrane includes a non-woven fabric base membrane layer, a polysulfone and a polyethylene oxide-polybenzyl methacrylate-polyethylene oxide composite layer, and a polyamide layer stacked in sequence.

[0139] Example 3

[0140] This embodiment provides a method for preparing a fast-dissolving reverse osmosis base membrane, the preparation method comprising the following steps:

[0141] S1. Preparation of casting solution:

[0142] 300 g of polysulfone pellets (molecular weight of 71000 Da) were dissolved in 2300 g of DMF, heated and stirred at 60° C. for 12 h, and vacuum degassed to obtain a precasting membrane liquid containing polysulfone for later use; 40 g of polyacrylamide-poly (4-hydroxymethylstyrene) (molecular weight of 8800 Da) was dissolved in 60 g of THF, 100 g of water was slowly added dropwise to THF, and stirred for 1 h for self-assembly to form nanoparticles of amphiphilic block copolymers, and then 200 g of a mixed solvent of water and DMF with a mass ratio of 1:1 was added, and stirring was continued for 1 h to obtain the solution containing the amphiphilic block copolymer for later use; the above-mentioned precasting membrane liquid containing polysulfone and the solution containing the amphiphilic block copolymer were mixed to obtain a casting liquid.

[0143] S2. Preparation of base membrane with modified polysulfone layer:

[0144] The casting liquid obtained in S1 was coated on a non-woven fabric, flattened with a 35 μm scraper, and then immersed in a mixed solvent of water and DMF at a mass ratio of 1:4 at 25°C to obtain a base membrane with a modified polysulfone layer (the thickness of the modified polysulfone layer on the base membrane was 35 μm).

[0145] S3. Preparation of polyamide layer:

[0146] The base membrane with a modified polysulfone layer obtained in S2 is first immersed in a 3wt% m-phenylenediamine solution (the solvent is water) for 1 min, the excess water phase on the surface is removed with a rubber roller, and then coated with a 0.15wt% trimesoyl chloride solution (the solvent is heptane) for 1 min, the excess oil phase on the surface is poured off, and the base membrane is placed in a 100°C forced air drying oven for curing for 15 min to form a polyamide layer with a thickness of 320 nm, thereby obtaining the fast-dissolving reverse osmosis base membrane; wherein the reverse osmosis base membrane includes a non-woven fabric base membrane layer, a polysulfone and a polyacrylic acid-polymethyl methacrylate composite layer, and a polyamide layer stacked in sequence.

[0147] Example 4

[0148] This embodiment provides a method for preparing a fast-dissolving reverse osmosis base membrane, which is different from Embodiment 1 only in that, in S1, polyacrylic acid-polymethyl methacrylate is replaced with polyacrylic acid-polybenzyl methacrylate of equal mass, and the other steps are exactly the same as those in Embodiment 1.

[0149] Example 5

[0150] This embodiment provides a method for preparing a fast-dissolving reverse osmosis base membrane, which is different from Embodiment 1 only in that, in S1, polyacrylic acid-polymethyl methacrylate is replaced with polyacrylamide-polymethyl methacrylate of equal mass, and the other steps are completely consistent with Embodiment 1.

[0151] Example 6

[0152] This embodiment provides a method for preparing a fast-dissolving reverse osmosis base membrane, which is different from the embodiment 1 only in that, in S1, the method for preparing the solution containing the amphiphilic block copolymer is:

[0153] 10 g of polyacrylic acid-polymethyl methacrylate (molecular weight 11000 Da) was directly dissolved in a mixed solvent of 50 g of DMF, 90 g of THF and 150 g of water, and stirred at room temperature for 3 h to obtain a solution containing an amphiphilic block copolymer. The other steps were exactly the same as in Example 1.

[0154] Example 7

[0155] This embodiment provides a method for preparing a fast-dissolving reverse osmosis base membrane, which is different from the embodiment 1 only in that, in S1, the method for preparing the solution containing the amphiphilic block copolymer is:

[0156] 10 g of polyacrylic acid-polymethyl methacrylate (molecular weight 11000 Da) was dissolved in 140 g of THF, 150 g of water was slowly added dropwise to THF, and stirred for 1 hour for self-assembly to obtain the solution containing the amphiphilic block copolymer, which was set aside. The other steps were completely consistent with Example 1.

[0157] Comparative Example 1

[0158] This comparative example provides a method for preparing a reverse osmosis base membrane, and the method for preparing the reverse osmosis base membrane comprises the following steps:

[0159] S1. Preparation of casting solution:

[0160] 540 g of polysulfone pellets (molecular weight 71000 Da) were dissolved in 2260 g of DMF, heated and stirred at 60° C. for 12 h, and vacuum degassed to obtain a casting solution.

[0161] S2. Preparation of polysulfone-based membrane:

[0162] The casting solution obtained in S1 was coated on a nonwoven fabric, flattened with a 35 μm scraper, and then immersed in pure water at 30° C. to obtain a base film with a polysulfone layer (the thickness of the polysulfone layer on the base film was 35 μm).

[0163] S3. Preparation of polyamide layer:

[0164] The polysulfone base membrane obtained by S2 is first immersed in a 2wt% m-phenylenediamine solution (the solvent is water) for 1 min, the excess water phase on the surface is removed with a rubber roller, and then coated with a 0.1wt% trimesoyl chloride solution (the solvent is hexane) for 1 min, the excess oil phase on the surface is poured off, and placed in a 100°C forced air drying oven for curing for 10 min to form a polyamide layer with a thickness of 190 nm, thereby obtaining the fast-dissolving reverse osmosis base membrane; wherein the reverse osmosis base membrane includes a non-woven fabric base membrane layer, a polysulfone layer, and a polyamide layer stacked in sequence.

[0165] Comparative Example 2

[0166] This comparative example provides a method for preparing a reverse osmosis base membrane, and the method for preparing the reverse osmosis base membrane comprises the following steps:

[0167] S1. Preparation of casting solution:

[0168] 540 g of polysulfone pellets (molecular weight 71000 Da) were dissolved in 2260 g of DMF, heated and stirred at 60° C. for 12 h, and vacuum degassed to obtain a casting solution.

[0169] S2. Preparation of polysulfone-based membrane:

[0170] The casting solution obtained in S1 was coated on a nonwoven fabric, flattened with a 35 μm scraper, and then immersed in pure water at 30° C. to obtain a base film with a polysulfone layer (the thickness of the polysulfone layer on the base film was 35 μm).

[0171] S3. Preparation of amphiphilic block copolymer membrane:

[0172] 10 g of polyacrylic acid-polymethyl methacrylate (molecular weight 11000 Da) was dissolved in 90 g of THF, 100 g of water was slowly added dropwise to THF, and stirred for 1 hour for self-assembly to form nanoparticles of amphiphilic block copolymers, and then 100 g of a mixed solvent of water and DMF with a mass ratio of 1:1 was added, and stirring was continued for 2 hours to obtain the solution containing the amphiphilic block copolymer, which was set aside; the solution containing the amphiphilic block copolymer was completely coated on the polysulfone-based membrane obtained in S2, flattened with a scraper, and then immersed in pure water at 30°C to form an amphiphilic block copolymer membrane, thereby obtaining a double-layer modified composite membrane.

[0173] S4. Preparation of polyamide layer:

[0174] The double-layer modified composite membrane obtained by S3 is first immersed in a 2wt% m-phenylenediamine solution (the solvent is water) for 1 min, the excess water phase on the surface is removed with a rubber roller, and then coated with a 0.1wt% trimesoyl chloride solution (the solvent is hexane) for 1 min, the excess oil phase on the surface is poured off, and the membrane is placed in a 100°C forced air drying oven for curing for 10 min to form a polyamide layer with a thickness of 200 nm, thereby obtaining the fast-dissolving reverse osmosis base membrane; wherein the reverse osmosis base membrane includes a non-woven fabric base membrane layer, a polysulfone layer, an amphiphilic block copolymer layer and a polyamide layer stacked in sequence.

[0175] Comparative Example 3

[0176] This comparative example provides a method for preparing a reverse osmosis base membrane, which is different from Example 1 only in that, in S1, polyacrylic acid-polymethyl methacrylate is replaced with polyacrylic acid of equal mass, and the other steps are consistent with Example 1.

[0177] Test Example 1

[0178] Pore ​​size distribution test

[0179] Test samples: the fast-dissolving reverse osmosis base membranes provided in Examples 1 to 7 and the reverse osmosis base membranes provided in Comparative Examples 1 to 3.

[0180] Test method: Use a pore size distribution tester to test the pore size distribution of the reverse osmosis base membrane.

[0181] The specific test results are shown in Table 1 and Figure 1 and Figure 2 As shown:

[0182] Table 1

[0183]

[0184]

[0185] As shown in Table 1, the base membrane prepared by the method for preparing the reverse osmosis base membrane with rapid dissolution of the invention has a membrane structure with a larger surface area and optimized pore distribution, and the pore size distribution is more uniform.

[0186] Test Example 2

[0187] TOC Dissolution Test

[0188] Test samples: the fast-dissolving reverse osmosis base membranes provided in Examples 1 to 7 and the reverse osmosis base membranes provided in Comparative Examples 1 to 3.

[0189] Test method: Soaking for the first time: Soak the reverse osmosis base membrane in pure water at 25°C for 30 minutes, then take it out and test the TOC content in the solution. Repeat the operation for the second to fifth soaking. The TOC value of the pure water used to soak the membrane is about 0.4ppm. At low TOC, the interference of pure water cannot be ignored.

[0190] The specific test results are shown in Table 2 and Figure 3 As shown:

[0191] Table 2

[0192]

[0193] As shown in Table 2, the present invention designs a hydrophilic base membrane with uniform pore structure, a membrane structure with a larger surface area and optimized pore distribution, improves the dissolution efficiency of the membrane, and ensures that the membrane releases the required substances uniformly and quickly during the dissolution process. The reverse osmosis membrane prepared on the basis of the base membrane greatly improves the dissolution rate of TOC.

[0194] Test Example 3

[0195] Test samples: the fast-dissolving reverse osmosis base membranes provided in Examples 1 to 8 and the reverse osmosis base membranes provided in Comparative Examples 1 to 4.

[0196] Test method: The test pressure is 1.03MPa, the raw water is 1500ppm sodium chloride aqueous solution, the concentrated water flow rate is 3.5GPM, the pH value of the raw water is 7-7.5, and the ambient temperature is 25℃.

[0197] The flux is calculated by the volume of water passing through the reverse osmosis membrane in a certain period of time; the calculation 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.

[0198] The desalination rate is calculated by the concentration of the concentrated water and the concentration of the permeate; the calculation formula is: R = (1-C1 / C0) × 100%, where C1 is the concentration of the concentrated water and C0 is the concentration of the permeate.

[0199] The specific test results are shown in Table 3 below:

[0200] Table 3

[0201]

[0202]

[0203] As shown in Table 3, the reverse osmosis membrane performance prepared by the above steps, in the embodiment, due to the increased hydrophilicity of the base membrane, the flux of the prepared reverse osmosis membrane increases, and this modification has little effect on the desalination rate of the membrane. It can be shown that the reverse osmosis membrane prepared on the base membrane can effectively reduce the TOC dissolution amount of the reverse osmosis membrane material and accelerate the TOC dissolution process to ensure that the predetermined water quality standard can be quickly reached in the early stage of membrane use, thereby improving the performance stability of the membrane and reducing adverse effects in the production process.

[0204] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a fast dissolving reverse osmosis base membrane, characterized in that: The preparation method comprises: Mixing a precasting solution containing polysulfone and a solution containing an amphiphilic block copolymer to obtain a casting solution; The casting solution is applied to the surface of a substrate to obtain a substrate having a wet film layer; the substrate having the wet film layer is immersed in a coagulation bath to obtain a base film having a modified polysulfone layer by a non-solvent induced phase transition method; The base membrane with the modified polysulfone layer is sequentially contacted with an aqueous monomer solution containing m-phenylenediamine and an oily monomer solution containing trimesoyl chloride, and then solidified to form a polyamide layer, thereby obtaining the fast-dissolving reverse osmosis base membrane.

2. The method for preparing a fast dissolving reverse osmosis base membrane according to claim 1, characterized in that: The mass ratio of the polysulfone to the amphiphilic block copolymer is (12-20):(0.001-10); Preferably, the casting solution comprises, by mass percentage, 12-20% polysulfone and 0.001-10% amphiphilic block copolymer, with the remainder being a mixed solvent.

3. The method for preparing a fast dissolving reverse osmosis base membrane according to claim 1 or 2, characterized in that: The structure of the amphiphilic block copolymer includes any one of AB type copolymer, ABA type copolymer or ABC type copolymer or a combination of at least two thereof; Wherein, the polymer segments A, B, and C are each independently selected from any one of polyacrylic acid, polyacrylamide, polyethylene oxide, poly-4-vinylpyridine, polyglycidyl acrylate, poly-N-isopropylacrylamide, polystyrene, polymethyl methacrylate, polybenzyl methacrylate, poly-4-hydroxymethylstyrene, or polyhexafluorobutyl methacrylate, and the polymer segments A, B, and C have at least one hydrophilic segment and one hydrophobic segment; Preferably, the molecular weight of the polysulfone is 10000 to 100000 Da; Preferably, the molecular weight of the amphiphilic block copolymer is 2000-50000 Da.

4. The method for preparing a fast dissolving reverse osmosis base membrane according to claim 1, characterized in that: The steps of configuring the polysulfone-containing precast membrane solution include: Dissolving polysulfone in an organic solvent, heating and stirring, and vacuum degassing to obtain the polysulfone-containing precast membrane solution; Preferably, the heating and stirring temperature is 50 to 70° C., and the heating and stirring time is 12 to 24 hours; Preferably, the polysulfone-containing precast membrane solution comprises, by mass percentage, 10-20% polysulfone and the remainder being an organic solvent; Preferably, the organic solvent includes any one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone, or a combination of at least two thereof.

5. The method for preparing a fast dissolving reverse osmosis base membrane according to claim 1, characterized in that: The step of preparing the solution containing the amphiphilic block copolymer comprises: The amphiphilic block copolymer is dissolved in a good solvent, and a poor solvent is added dropwise for self-assembly to form nanoparticles of the amphiphilic block copolymer, and a mixed solvent of a good solvent and a poor solvent is added for dilution by stirring to obtain a solution containing the amphiphilic block copolymer; Preferably, the good solvent comprises any one of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone, or a combination of at least two thereof; Preferably, the poor solvent includes any one of water, methanol, ethanol or acetone, or a combination of at least two thereof; Preferably, the mass ratio of the amphiphilic block copolymer, the good solvent, the poor solvent, the mixed solvent and the precast membrane solution is 1:(1-20):(1-20):(1-200):(100-500); Preferably, in the mixed solvent, the mass ratio of the good solvent to the poor solvent is (10-90):(10-90); Preferably, the temperature for self-assembly by dripping a poor solvent is 10 to 40° C., and the self-assembly time is 0.5 to 2 h; Preferably, the stirring and dilution temperature is 10-40° C., and the stirring and dilution time is 0.5-2 h.

6. The method for preparing a fast dissolving reverse osmosis base membrane according to claim 1, characterized in that: The substrate comprises a nonwoven fabric; Preferably, the coagulation bath comprises any one or a combination of at least two of water, methanol, ethanol, acetone, N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone; Preferably, the temperature of the coagulation bath is 20 to 60°C; Preferably, the thickness of the modified polysulfone layer is 20-50 μm.

7. The method for preparing a fast dissolving reverse osmosis base membrane according to claim 1, characterized in that: The aqueous phase monomer solution containing m-phenylenediamine comprises, by mass percentage, 0.5-4% m-phenylenediamine and the remainder being an aqueous phase solvent; Preferably, the oil phase monomer solution containing trimesoyl chloride comprises, by weight percentage: 0.01-0.3% trimesoyl chloride, and the remainder is oil phase solvent; Preferably, the aqueous phase solvent comprises water; Preferably, the aqueous phase solvent further comprises any one of dimethyl sulfoxide, methanol or isopropanol or a combination of at least two thereof; Preferably, the oil phase solvent comprises any one of hexane, heptane or isoparaffin, or a combination of at least two thereof; Preferably, the curing temperature is 70-100°C and the curing time is 2-60 minutes; Preferably, the thickness of the polyamide layer is 100-500 nm.

8. A reverse osmosis base membrane, characterized in that: The reverse osmosis base membrane is prepared by the preparation method according to any one of claims 1 to 7.

9. The reverse osmosis base membrane according to claim 8, characterized in that: The reverse osmosis base membrane comprises a non-woven fabric layer, a modified polysulfone composite layer, and a polyamide layer which are stacked in sequence; Preferably, the pore size of the reverse osmosis base membrane is 10 to 400 nm; Preferably, the pore size distribution parameters of the reverse osmosis base membrane include: the pore volume of pores with a pore size of 200 to 250 nm accounts for 80 to 100% of the total pore volume; Preferably, the TOC dissolution amount of the reverse osmosis base membrane is 0.1 to 20 ppm / dm 2 The TOC dissolution rate of the reverse osmosis base membrane is 0.003-1 ppm / dm 2 / min; Preferably, the flux of the reverse osmosis base membrane is above 58LMH; Preferably, the desalination rate of the reverse osmosis base membrane is above 99%.

10. Use of the reverse osmosis base membrane according to claim 8 or 9 in preparing ultrapure water.

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