Anti-pollution polyurea composite reverse osmosis membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of membrane separation and water treatment, in particular to an anti-pollution polyurea composite reverse osmosis membrane as well as a preparation method and application thereof. According to the preparation method, a polyamine monomer of a water phase solution and an aromatic polyisocyanate monomer of an organic phase solution are used for constructing a polymerization reaction system to form a urea bond structure, and terminal sealing treatment is cooperatively performed on a polyurea selection layer, so that the compact, flat and hydrophilic polyurea selection layer can be prepared. And the preparation method is simple, mild in condition, low in energy consumption, robust in process, wide in parameter window and suitable for large-scale production. The prepared anti-pollution polyurea composite reverse osmosis membrane has excellent anti-pollution performance and separation performance, can achieve excellent balance between maintenance of initial flux and long-term stability, and has excellent anti-pollution performance and separation performance. The reverse osmosis membrane shows low irreversible pollution rate and good cleaning recoverability to organic / inorganic typical sewage plugging substances, can well meet industrial requirements, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of membrane separation and water treatment, in particular to an anti-fouling polyurea composite reverse osmosis membrane, a preparation method and application thereof, and in particular to the application of the reverse osmosis membrane in water softening and seawater / brackish water desalination. BACKGROUND

[0002] As the core unit operation of municipal deep purification, industrial make-up water softening and seawater / brackish water desalination, reverse osmosis (RO) is widely deployed due to its high rejection rate, modularity and small footprint. The current mainstream polyamide (PA) RO membrane is generated by the condensation of acyl chloride / amine at the oil / water interface, and has a mature industrialization basis. However, the surface micro-morphology and end group chemistry of the PA selective layer often cause the following problems: first, the surface roughness and nano-wrinkles provide initial attachment sites for organic matter and microorganisms; second, residual active / hydrophobic microzones easily induce irreversible adsorption and interface densification; third, when the pretreatment is insufficient, colloids and scaling salts work together to amplify the defect amplification effect and trigger flux decline. At present, although traditional modifications (hydrophilic / amphiphilic coating, surface grafting, nano-filler, etc.) on the material side can reduce the interfacial energy to some extent, they often face a trade-off between coating stability, leaching risk, scalability and cost in long-term circulation; at the same time, simply pursuing a thinner selective layer without precise control of the film formation dynamics often leads to an increase in defect rate or surface roughness, thereby offsetting the expected benefits.

[0003] At present, most of the published schemes for reverse osmosis focus on chemical stability (such as oxidation resistance / chemical corrosion resistance) or single-point modification, however, there is a lack of systematic, replicable and scalable process window and verification path for the complex fouling scenario of softening and seawater / brackish water desalination. Although existing technologies show potential in reducing transient gel, reducing pinholes and smoothing the interface at the laboratory level, their optimal interval, amplification tolerance and contribution to long-term irreversible fouling and cleaning recoverability still lack systematic data support.

[0004] In addition, the existing reverse osmosis technology needs to be improved in terms of anti-fouling, separation performance, maintaining initial flux and long-term stable balance, reducing operating energy consumption and cleaning cost, and improving the overall life cycle economy of the system. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the first object of the present application is to provide a preparation method of an anti-fouling polyurea composite reverse osmosis membrane, which is simple, robust, suitable for large-scale production, easy to integrate into existing production lines, and has low operating energy consumption and cleaning cost, and good overall life cycle economy of the system.

[0006] To overcome the shortcomings of the prior art, the second objective of this invention is to provide an antifouling polyurea composite reverse osmosis membrane, which has excellent antifouling and separation performance, and can achieve an excellent balance between maintaining initial flux and long-term stability.

[0007] The third objective of this invention is to provide an application of an antifouling polyurea composite reverse osmosis membrane.

[0008] To achieve the first objective of the invention, the technical solution adopted by the present invention is as follows:

[0009] This invention provides a method for preparing an antifouling polyurea composite reverse osmosis membrane, comprising the following steps:

[0010] S1. The support layer is brought into contact with an aqueous solution containing polyamine monomers, and after drying, an aqueous layer is formed on the support layer.

[0011] S2. The aqueous phase layer is brought into contact with an organic phase solution containing aromatic polyisocyanate monomers to carry out an interfacial polymerization reaction to form a polyurea selective layer.

[0012] S3. The polyurea selective layer is subjected to end sealing treatment, followed by cleaning and drying curing to obtain the antifouling polyurea composite reverse osmosis membrane.

[0013] The end-sealing treatments in steps S1, S2, and S3 are all carried out at room temperature, which has the advantages of mild process conditions and energy saving.

[0014] The end-sealing process in step S3 can make the chemical structure of the reverse osmosis membrane more stable.

[0015] This invention discloses a method for preparing an antifouling polyurea composite reverse osmosis membrane. The method involves constructing a polymerization reaction system using polyamine monomers in an aqueous phase solution and aromatic polyisocyanate monomers in an organic phase solution to form a urea bond structure. This synergistic process performs end-capping treatment on the polyurea selective layer, resulting in a dense, smooth, and hydrophilic polyurea selective layer. Furthermore, based on the urea bond structure formed by the polymerization reaction system and the strong hydrogen bonding effect of the urea bond structure, the prepared reverse osmosis membrane has a three-dimensional network structure. Therefore, this reverse osmosis membrane exhibits a high salt rejection rate and excellent antifouling performance, with a salt rejection rate exceeding 98%.

[0016] The polyurea (PU) composite reverse osmosis membrane of this invention differs from the PA system. The polyurea selective layer is generated by the addition reaction of isocyanate and amine, with mild reaction conditions, few side reactions, and good compatibility with various support layers and morphologies. The key to polyurea interfacial polymerization (IP) lies in the coupling of interfacial mass transfer and reaction: the diffusion behavior of the aqueous / oil phase, the control of swelling and viscosity by solvent / co-solvent, and the timing design of the "short-term contact between interfacial polymerization reaction and end-capping treatment" all significantly affect the nucleation rate, gel front advancement, final surface morphology, and end-group exposure. Through the synergistic effect of these three process steps, a thinner, denser, smoother, and hydrophilic PU selective layer can be constructed, reducing irreversible adsorption and initial microbial adhesion from the source.

[0017] Further, in step S1, the aqueous solution contains a surfactant; and / or, the surfactant has a mass concentration of 0.1 wt% to 0.5 wt% in the aqueous solution; and / or

[0018] The surfactant is at least one of sodium dodecyl sulfate, sodium lauryl ether sulfate, polysorbate 80, and polyvinyl alcohol.

[0019] In the interfacial polymerization of some polyamine monomers and aromatic polyisocyanate monomers, surfactants regulate the interfacial polymerization process, thereby adjusting and improving the separation performance of reverse osmosis membranes. Adding trace amounts of surfactants to the aqueous solution can achieve wetting and interfacial stabilization.

[0020] Further, in step S1, the polyamine monomer is at least one selected from piperazine (PIP), 4,4'-bipiperidine (BP), N,N'-bis(3-aminopropyl)propane-1,3-diamine (TAE), diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TPTA); and / or, the mass concentration of the polyamine monomer in the aqueous solution is 0.1wt%~5wt%; and / or

[0021] The support layer is one of a flat sheet microfiltration membrane, a flat sheet ultrafiltration membrane, a hollow fiber microfiltration membrane, or a hollow fiber ultrafiltration membrane; and / or, the material of the support layer is selected from polyvinylidene fluoride, polyacrylonitrile, polysulfone, polyethersulfone, or polyimide; and / or

[0022] The contact time is 0.5 min to 5 min; and / or

[0023] The drying method is as follows: after removing the residual liquid from the surface of the support layer, it is allowed to air dry naturally.

[0024] Further, in step S2, the aromatic polyisocyanate monomer is at least one selected from 1,3-diisophenyl cyanate (PDI) and its derivatives, toluene diisocyanate (TDI) and its derivatives, methyl diphenyl diisocyanate (MPDI) and its derivatives, benzene 1,3,5-triisocyanate (TMI) and its derivatives, and diphenylmethane diisocyanate (MDI) and its derivatives; and / or

[0025] The organic solvent in the organic phase solution is a single solvent system or a co-solvent system; and / or

[0026] The single solvent system is one of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, or xylene; and / or

[0027] The co-solvent system is a mixed solution of a weakly polar solvent and a moderately polar solvent; and / or

[0028] The weakly polar solvent is one of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, or xylene; the medium-to-strong polar solvent is one of methanol, ethanol, isopropanol, dichloromethane, trichloromethane, or ethyl acetate; and / or

[0029] The medium-to-strong polar solvent accounts for 1% to 80% of the volume percentage of the co-solvent system.

[0030] Furthermore, in step S2, the mass concentration of the aromatic polyisocyanate monomer in the organic phase solution is 0.01 wt% to 1.0 wt%; and / or

[0031] The interfacial polymerization reaction takes place over a period of 0.5 min to 5 min; and / or

[0032] The contact method is single-sided dip coating, double-sided dip coating, or slot spraying.

[0033] Furthermore, in step S3, before the end-sealing treatment, excess organic phase solution is removed from the surface of the polyurea selective layer; and / or

[0034] The end-sealing treatment is performed by contacting the polyurea selective layer with an organic phase solution containing aromatic polyisocyanate monomers or an acyl chloride organic solution; and / or, the contact time is 10s to 120s; and / or, the contact method is single-sided dip coating, double-sided dip coating, or slot spraying; and / or

[0035] The organic phase solution contains aromatic polyisocyanate monomers at a mass concentration of 0.005 wt% to 0.2 wt%; and / or

[0036] The acyl chloride organic solution has a mass concentration of 0.005 wt% to 0.2 wt%; and / or

[0037] The organic solvent in the organic phase solution and the acyl chloride organic solution is one of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, or xylene.

[0038] Furthermore, in step S3, after the end-sealing treatment, the polyurea selective layer is immersed or rinsed with a non-polar solvent for 5-10 seconds, followed by cleaning and drying / curing; and / or

[0039] The nonpolar solvent is one of benzene, carbon tetrachloride, dichloroethane, cyclohexane, or petroleum ether.

[0040] Furthermore, in step S3, the cleaning is performed using deionized water; and / or

[0041] The drying and curing temperature is 40℃~80℃, and the drying and curing time is 5min~60min. To achieve the second objective of the invention, the technical solution adopted by the present invention is as follows:

[0042] This invention provides an antifouling polyurea composite reverse osmosis membrane, which is prepared by the above-described method for preparing an antifouling polyurea composite reverse osmosis membrane.

[0043] The antifouling polyurea composite reverse osmosis membrane prepared by this invention has a stable membrane structure, an active layer with a three-dimensional network structure, and the advantages of being dense, flat and hydrophilic. Furthermore, the antifouling polyurea composite reverse osmosis membrane has excellent antifouling performance and separation performance.

[0044] To achieve the third objective of the invention, the technical solution adopted by the present invention is as follows:

[0045] This invention provides an application of an antifouling polyurea composite reverse osmosis membrane. The antifouling polyurea composite reverse osmosis membrane prepared by the above-described method is used in urban water softening, deep softening of boiler feedwater, brackish water desalination, or seawater desalination.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] (1) A method for preparing an antifouling polyurea composite reverse osmosis membrane according to the present invention involves constructing a polymerization reaction system by combining polyamine monomers in an aqueous phase solution with aromatic polyisocyanate monomers in an organic phase solution to form a urea bond structure. This system, along with the synergistic end-sealing treatment of the polyurea selective layer, enables the preparation of a dense, smooth, and hydrophilic polyurea selective layer. Furthermore, based on the urea bond structure formed by the polymerization reaction system and the strong hydrogen bonding effect of the urea bond structure, the resulting reverse osmosis membrane has a three-dimensional network structure, thus exhibiting a high salt rejection rate and excellent antifouling performance. Specifically, at 25... o Under conditions of C, 15.5 bar, and 2000 ppm NaCl, the salt rejection rate is ≥98.0%, and the water permeability coefficient is ≥1 L / m. -2 h -1 bar -1 It meets the requirements for softening / branching water desalination. Under typical mixed fouling conditions (bovine serum albumin / sodium alginate / humic acid system, BSA / SA / HA+ CaCO3 / SiO2), the irreversible fouling rate is ≤15%, and the flux recovery rate (FRR) is ≥90%.

[0048] (2) The present invention provides a method for preparing an antifouling polyurea composite reverse osmosis membrane. The preparation method is simple, the preparation conditions are mild, the energy consumption is low, the process is robust, the parameter window is wide, and it is compatible with various base membranes and equipment forms. It is suitable for the industrial preparation of flat fiber membranes and hollow fiber membranes and can be used for large-scale production. The interfacial polymerization reaction and end-sealing treatment are continuous production lines, and can achieve high salt rejection, low irreversible pollution and good cleaning recoverability. It is also easy to integrate into existing production lines, and the operating energy consumption and cleaning cost are low. The system has good economic performance throughout its entire life cycle.

[0049] (3) The antifouling polyurea composite reverse osmosis membrane of the present invention has excellent antifouling performance and separation performance, and can achieve an excellent balance between maintaining initial flux and long-term stability, and has excellent antifouling performance and separation performance.

[0050] (4) An application of the antifouling polyurea composite reverse osmosis membrane of the present invention, which can be applied to urban water softening, boiler feedwater deep softening, brackish water desalination or seawater desalination, can achieve the effect of high salt interception and low pollution, and exhibits low irreversible fouling rate and good cleaning recoverability for typical organic / inorganic fouling substances, which can well meet industrial needs and has good application prospects. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a surface SEM image of the antifouling polyurea composite reverse osmosis membrane (PIP-PDI membrane) prepared in Example 1 of the present invention.

[0053] Figure 2 This is a surface SEM image of the antifouling polyurea composite reverse osmosis membrane (PIP-TDI membrane) prepared in Example 2 of the present invention. Detailed Implementation

[0054] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0055] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. In this invention, the singular forms “a,” “described,” and “the” as used in the embodiments and appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0056] In this embodiment of the invention, a method for preparing an antifouling polyurea composite reverse osmosis membrane includes the following steps:

[0057] S1. The support layer is brought into contact with an aqueous solution containing polyamine monomers, and after drying, an aqueous layer is formed on the support layer.

[0058] S2. The aqueous phase layer is brought into contact with an organic phase solution containing aromatic polyisocyanate monomers to carry out an interfacial polymerization reaction to form a polyurea selective layer.

[0059] S3. The polyurea selective layer is subjected to end sealing treatment, followed by cleaning and drying curing to obtain the antifouling polyurea composite reverse osmosis membrane.

[0060] In some embodiments, in step S1, the aqueous solution contains a surfactant; and / or, the surfactant has a mass concentration of 0.1 wt% to 0.5 wt% in the aqueous solution; and / or

[0061] The surfactant is at least one of sodium dodecyl sulfate, sodium lauryl ether sulfate, polysorbate 80, and polyvinyl alcohol.

[0062] In some embodiments, in step S1, the polyamine monomer is at least one selected from piperazine (PIP), 4,4'-bipiperidine (BP), N,N'-bis(3-aminopropyl)propane-1,3-diamine (TAE), diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TPTA); and / or, the mass concentration of the polyamine monomer in the aqueous solution is 0.1 wt% to 5 wt%; and / or

[0063] The support layer is one of a flat sheet microfiltration membrane, a flat sheet ultrafiltration membrane, a hollow fiber microfiltration membrane, or a hollow fiber ultrafiltration membrane; and / or, the material of the support layer is selected from polyvinylidene fluoride, polyacrylonitrile, polysulfone, polyethersulfone, or polyimide; and / or

[0064] The contact time is 0.5 min to 5 min; and / or

[0065] The drying method is as follows: after removing the residual liquid from the surface of the support layer, it is allowed to air dry naturally.

[0066] In some embodiments, in step S2, the aromatic polyisocyanate monomer is at least one selected from 1,3-diisophenyl cyanate (PDI) and its derivatives, toluene diisocyanate (TDI) and its derivatives, methyl diphenyl diisocyanate (MPDI) and its derivatives, benzene 1,3,5-triisocyanate (TMI) and its derivatives, and diphenylmethane diisocyanate (MDI) and its derivatives; and / or

[0067] The organic solvent in the organic phase solution is a single solvent system or a co-solvent system; and / or

[0068] The single solvent system is one of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, or xylene; and / or

[0069] The co-solvent system is a mixed solution of a weakly polar solvent and a moderately polar solvent; and / or

[0070] The weakly polar solvent is one of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, or xylene; the medium-to-strong polar solvent is one of methanol, ethanol, isopropanol, dichloromethane, trichloromethane, or ethyl acetate; and / or

[0071] The medium-to-strong polar solvent accounts for 1% to 80% of the volume percentage of the co-solvent system.

[0072] In some embodiments, in step S2, the mass concentration of the aromatic polyisocyanate monomer in the organic phase solution is 0.01 wt% to 1.0 wt%; and / or

[0073] The interfacial polymerization reaction takes place over a period of 0.5 min to 5 min; and / or

[0074] The contact method is single-sided dip coating, double-sided dip coating, or slot spraying.

[0075] In some embodiments, before the end-sealing treatment in step S3, excess organic phase solution is removed from the surface of the polyurea selective layer; and / or

[0076] The end-sealing treatment is performed by contacting the polyurea selective layer with an organic phase solution containing aromatic polyisocyanate monomers or an acyl chloride organic solution; and / or, the contact time is 10s to 120s; and / or, the contact method is single-sided dip coating, double-sided dip coating, or slot spraying; and / or

[0077] The organic phase solution contains aromatic polyisocyanate monomers at a mass concentration of 0.005 wt% to 0.2 wt%; and / or

[0078] The acyl chloride organic solution has a mass concentration of 0.005 wt% to 0.2 wt%; and / or

[0079] The organic solvent in the organic phase solution and the acyl chloride organic solution is one of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, or xylene.

[0080] In some embodiments, in step S3, after the end-sealing treatment, the polyurea selective layer is immersed or rinsed with a non-polar solvent for 5-10 seconds, followed by cleaning and drying / curing; and / or

[0081] The nonpolar solvent is one of benzene, carbon tetrachloride, dichloroethane, cyclohexane, or petroleum ether.

[0082] In some embodiments, in step S3, the cleaning is performed using deionized water; and / or

[0083] The drying and curing temperature is 40℃~80℃, and the drying and curing time is 5min~60min.

[0084] In this embodiment of the invention, an antifouling polyurea composite reverse osmosis membrane is prepared by the above-described method for preparing an antifouling polyurea composite reverse osmosis membrane.

[0085] In this embodiment of the invention, an antifouling polyurea composite reverse osmosis membrane is applied in urban water softening, deep softening of boiler feedwater, brackish water desalination, or seawater desalination.

[0086] The following description is based on specific embodiments. Example 1

[0087] A method for preparing an antifouling polyurea composite reverse osmosis membrane (PIP-PDI membrane) includes the following steps:

[0088] A 0.1 wt% piperazine (PIP) aqueous solution was prepared and poured onto the surface of a polysulfone-based flat sheet microfiltration membrane. After immersion for 0.5 min, the remaining piperazine aqueous solution was poured off, and the membrane was allowed to air dry naturally, forming an aqueous phase layer on the surface of the flat sheet microfiltration membrane. A 0.01 wt% PDI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the above-mentioned flat sheet microfiltration membrane. An interfacial polymerization reaction was carried out for 5 min, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% PDI organic solution (hexane as the organic solvent) was used to dip-coat the formed polyurea selective layer onto one side of the membrane surface for 10 s for end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and placed in a 40°C oven to dry and cure for 5 min, thus obtaining the antifouling polyurea composite reverse osmosis membrane (PIP-PDI membrane). Example 2

[0089] A method for preparing an antifouling polyurea composite reverse osmosis membrane (PIP-TDI membrane) includes the following steps:

[0090] A 5 wt% piperazine (PIP) aqueous solution was prepared and poured onto the surface of a polyethersulfone (PES) flat-sheet ultrafiltration membrane. After immersion for 5 minutes, the remaining PIP aqueous solution was poured off, and the membrane was allowed to air dry naturally, forming an aqueous phase layer on the surface of the membrane. A 1 wt% TDI organic solution (petroleum ether as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the membrane. An interfacial polymerization reaction was carried out for 0.5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.2 wt% TDI organic solution (petroleum ether as the organic solvent) was used to double-sided dip-coat the formed polyurea selective layer onto the membrane surface for 120 seconds for end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in an 80°C oven for 60 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (PIP-TDI membrane). Example 3

[0091] A method for preparing an antifouling polyurea composite reverse osmosis membrane (PIP-MPDI membrane) includes the following steps:

[0092] An aqueous solution containing 3 wt% piperazine (PIP) and 0.5 wt% sodium dodecyl sulfate (SDS) was prepared and poured onto the surface of a hollow fiber microfiltration membrane made of polyimide. After immersion for 5 minutes, the remaining aqueous solution was poured off, and the membrane was allowed to air dry naturally, forming an aqueous phase layer on the surface of the hollow fiber microfiltration membrane. A 0.05 wt% MPDI organic solution (n-heptane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the hollow fiber microfiltration membrane. An interfacial polymerization reaction was carried out for 3 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.1 wt% MDI organic solution (n-heptane as the organic solvent) was applied to the surface of the formed polyurea selective layer by slit spraying for 120 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in an oven at 80°C for 60 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (PIP-MPDI membrane). Example 4

[0093] A method for preparing an antifouling polyurea composite reverse osmosis membrane (PIP-TMI membrane) includes the following steps:

[0094] A 4 wt% piperazine (PIP) aqueous solution was prepared and poured onto the surface of a hollow fiber ultrafiltration membrane made of polyacrylonitrile. After immersion for 5 minutes, the remaining piperazine aqueous solution was poured off, and the membrane was allowed to air dry naturally, forming an aqueous phase layer on the surface of the hollow fiber ultrafiltration membrane. A 1 wt% TMI organic solution (cyclohexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the hollow fiber ultrafiltration membrane. An interfacial polymerization reaction was carried out for 2 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% TMI organic solution (cyclohexane as the organic solvent) was applied to the surface of the formed polyurea selective layer by slit spraying for 20 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 50°C oven for 8 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (PIP-TMI membrane). Example 5

[0095] A method for preparing an antifouling polyurea composite reverse osmosis membrane (BP-PDI membrane) includes the following steps:

[0096] A 1 wt% aqueous solution of 4,4'-bipiperidine (BP) was prepared and poured onto the surface of a polyvinylidene fluoride (PVDF) flat sheet microfiltration membrane. After immersion for 3 minutes, the remaining BP solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the membrane. A 0.5 wt% organic solution of polyurea diisocyanate (PDI) (with n-dodecane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% organic solution of PDI (with n-dodecane as the organic solvent) was applied to both sides of the polyurea selective layer for 50 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 60°C oven for 20 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (BP-PDI membrane). Example 6

[0097] A method for preparing an antifouling polyurea composite reverse osmosis membrane (BP-TDI membrane) includes the following steps:

[0098] A 4 wt% aqueous solution of 4,4'-bipiperidine (BP) was prepared and poured onto the surface of a polyethersulfone (PES) flat-sheet ultrafiltration membrane. After immersion for 3 minutes, the remaining BP solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the membrane surface. A 0.2 wt% organic TDI solution (toluene as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% organic TDI solution (toluene as the organic solvent) was used to dip-coat the formed polyurea selective layer onto one side of the membrane surface for 10 seconds for end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (BP-TDI membrane). Example 7

[0099] A method for preparing an antifouling polyurea composite reverse osmosis membrane (BP-MPDI membrane) includes the following steps:

[0100] A 2 wt% aqueous solution of 4,4'-bipiperidine (BP) was prepared and poured onto the surface of a hollow fiber microfiltration membrane made of polyethersulfone. After immersion for 5 minutes, the remaining BP solution was poured off, and the membrane was allowed to air dry naturally, forming an aqueous phase layer on the surface of the hollow fiber microfiltration membrane. A 0.05 wt% organic solution of MPDI (xylene as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the hollow fiber microfiltration membrane. An interfacial polymerization reaction was carried out for 5 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% organic solution of MPDI (xylene as the organic solvent) was applied to the surface of the formed polyurea selective layer by slit spraying for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (BP-MPDI membrane). Example 8

[0101] A method for preparing an antifouling polyurea composite reverse osmosis membrane (BP-TMI membrane) includes the following steps:

[0102] A 3 wt% aqueous solution of 4,4'-bipiperidine (BP) was prepared and poured onto the surface of a hollow fiber ultrafiltration membrane made of polysulfone. After immersion for 3 minutes, the remaining BP solution was poured off, and the membrane was allowed to air dry naturally, forming an aqueous phase layer on the surface of the hollow fiber ultrafiltration membrane. A 0.2 wt% TMI organic solution (a mixture of n-hexane and methanol in a volume ratio of 4:1) was prepared and poured onto the surface of the aqueous phase layer of the hollow fiber ultrafiltration membrane. Interfacial polymerization was carried out for 3 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% TMI organic solution (a mixture of n-hexane and methanol in a volume ratio of 4:1) was applied to the surface of the formed polyurea selective layer by slit spraying for 10 seconds to perform end-sealing treatment, resulting in a treated membrane. The membrane is then cleaned with deionized water and then dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (BP-TMI membrane). Example 9

[0103] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TAE-PDI membrane) includes the following steps:

[0104] A 4 wt% aqueous solution of N,N'-bis(3-aminopropyl)propane-1,3-diamine (TAE) was prepared and poured onto the surface of a polyethersulfone-based flat sheet microfiltration membrane. After immersion for 3 minutes, the remaining TAE solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the flat sheet microfiltration membrane. A 0.3 wt% PDI organic solution (a mixture of petroleum ether and ethyl acetate in a 1:4 volume ratio) was prepared and poured onto the surface of the aqueous phase layer of the above-mentioned flat sheet microfiltration membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% PDI organic solution (a mixture of petroleum ether and ethyl acetate in a 1:4 volume ratio) was applied to the surface of the formed polyurea selective layer via slit spraying for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The membrane is then cleaned with deionized water and then dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (TAE-PDI membrane). Example 10

[0105] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TAE-TDI membrane) includes the following steps:

[0106] A 3 wt% aqueous solution of N,N'-bis(3-aminopropyl)propane-1,3-diamine (TAE) was prepared and poured onto the surface of a polyethersulfone-based flat sheet microfiltration membrane. After immersion for 5 minutes, the remaining TAE solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the flat sheet microfiltration membrane. A 0.1 wt% TDI organic solution (a mixture of n-hexane and ethanol in a volume ratio of 10:1) was prepared and poured onto the surface of the aqueous phase layer of the above-mentioned flat sheet microfiltration membrane. An interfacial polymerization reaction was carried out for 5 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% TDI organic solution (a mixture of n-hexane and ethanol in a volume ratio of 10:1) was applied to the surface of the formed polyurea selective layer by slit spraying for 10 seconds to perform end-sealing treatment, resulting in a treated membrane. The membrane is then cleaned with deionized water and then dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (TAE-TDI membrane). Example 11

[0107] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TAE-MPDI membrane) includes the following steps:

[0108] A 2 wt% aqueous solution of N,N'-bis(3-aminopropyl)propane-1,3-diamine (TAE) was prepared and poured onto the surface of a polysulfone-based sheet ultrafiltration membrane. After immersion for 3 minutes, the remaining TAE solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the sheet ultrafiltration membrane surface. A 0.05 wt% MPDI organic solution (a mixture of n-hexane and isopropanol in a volume ratio of 5:1) was prepared and poured onto the surface of the aqueous phase layer of the sheet ultrafiltration membrane. Interfacial polymerization was carried out for 3 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% MPDI organic solution (a mixture of n-hexane and isopropanol in a volume ratio of 5:1) was used to dip-coat the formed polyurea selective layer onto one side of the membrane surface for 10 seconds to perform end-sealing treatment, resulting in a treated membrane. The membrane is then cleaned with deionized water and then dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (TAE-MPDI membrane). Example 12

[0109] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TAE-TMI membrane) includes the following steps:

[0110] A 1 wt% aqueous solution of N,N'-bis(3-aminopropyl)propane-1,3-diamine (TAE) was prepared and poured onto the surface of a polyethersulfone (PES) flat-sheet ultrafiltration membrane. After immersion for 2 minutes, the remaining TAE solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the membrane. A 0.2 wt% TMI organic solution (a mixture of n-hexane and dichloromethane in a 5:1 volume ratio) was prepared and poured onto the surface of the aqueous phase layer of the flat-sheet ultrafiltration membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% TMI organic solution (a mixture of n-hexane and dichloromethane in a 5:1 volume ratio) was used to dip-coat the formed polyurea selective layer onto one side of the membrane surface for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The membrane is then cleaned with deionized water and then dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (TAE-TMI membrane). Example 13

[0111] A method for preparing an antifouling polyurea composite reverse osmosis membrane (DETA-PDI membrane) includes the following steps:

[0112] A 0.5 wt% aqueous solution of diethylenetriamine (DETA) was prepared and poured onto the surface of a polyethersulfone (PES) flat-sheet ultrafiltration membrane. After immersion for 5 minutes, the remaining DETA solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the membrane surface. A 0.5 wt% PDI organic solution (a mixture of n-hexane and chloroform in a 5:1 volume ratio) was prepared and applied to the aqueous phase layer of the membrane via slit spraying. Interfacial polymerization was then carried out for 5 minutes, after which the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% PDI organic solution (a mixture of n-hexane and chloroform in a 5:1 volume ratio) was applied to both sides of the polyurea selective layer for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The membrane is then cleaned with deionized water and then dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (DETA-PDI membrane). Example 14

[0113] A method for preparing an antifouling polyurea composite reverse osmosis membrane (DETA-TDI membrane) includes the following steps:

[0114] A 2 wt% aqueous solution of diethylenetriamine (DETA) was prepared and poured onto the surface of a polyethersulfone (PES) flat-sheet ultrafiltration membrane. After immersion for 2 minutes, the remaining DETA solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the membrane surface. A 0.2 wt% organic solution of TDI (n-decane) was prepared and applied to the aqueous phase layer of the membrane via single-sided dip-coating. Interfacial polymerization was then carried out for 5 minutes, after which the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% organic solution of acyl chloride (n-decane) was applied to both sides of the polyurea selective layer for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes, yielding an antifouling polyurea composite reverse osmosis membrane (DETA-TDI membrane). Example 15

[0115] A method for preparing an antifouling polyurea composite reverse osmosis membrane (DETA-MPDI membrane) includes the following steps:

[0116] A 3 wt% aqueous solution of diethylenetriamine (DETA) was prepared and poured onto the surface of a polyethersulfone (PES) flat-sheet ultrafiltration membrane. After immersion for 3 minutes, the remaining DETA solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the membrane surface. A 0.1 wt% organic solution of MPDI (hexane) was prepared and applied to the aqueous phase layer of the membrane via double-sided dip-coating. Interfacial polymerization was carried out for 3 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.2 wt% organic solution of acyl chloride (hexane) was applied to the polyurea selective layer via double-sided dip-coating for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes, yielding the antifouling polyurea composite reverse osmosis membrane (DETA-MPDI membrane). Example 16

[0117] A method for preparing an antifouling polyurea composite reverse osmosis membrane (DETA-TMI membrane) includes the following steps:

[0118] A 1 wt% aqueous solution of diethylenetriamine (DETA) was prepared and poured onto the surface of a polyethersulfone (PES) flat sheet microfiltration membrane. After immersion for 5 minutes, the remaining DETA solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the membrane. A 0.1 wt% TMI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.1 wt% acyl chloride organic solution (hexane as the organic solvent) was applied to both sides of the polyurea selective layer for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (DETA-TMI membrane). Example 17

[0119] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TETA-PDI membrane) includes the following steps:

[0120] A 0.5 wt% triethylenetetramine (TETA) aqueous solution was prepared and poured onto the surface of a polysulfone-based flat sheet microfiltration membrane. After immersion for 3 minutes, the remaining TETA aqueous solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the flat sheet microfiltration membrane. A 0.3 wt% PDI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the above-mentioned flat sheet microfiltration membrane. An interfacial polymerization reaction was carried out for 5 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.05 wt% acyl chloride organic solution (hexane as the organic solvent) was used to double-sided dip-coat the formed polyurea selective layer onto the membrane surface for 10 seconds to perform end-sealing treatment, obtaining a treated membrane. The treated membrane was then cleaned with deionized water and placed in a 40°C oven to dry and cure for 5 minutes, thus obtaining the antifouling polyurea composite reverse osmosis membrane (TETA-PDI membrane). Example 18

[0121] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TETA-TDI membrane) includes the following steps:

[0122] A 2 wt% triethylenetetramine (TETA) aqueous solution was prepared and poured onto the surface of a polyethersulfone (PES) flat sheet microfiltration membrane. After immersion for 3 minutes, the remaining TETA aqueous solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the membrane. A 0.2 wt% TDI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 3 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% TDI organic solution (hexane as the organic solvent) was applied to both sides of the polyurea selective layer for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes, yielding the antifouling polyurea composite reverse osmosis membrane (TETA-TDI membrane). Example 19

[0123] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TETA-MPDI membrane) includes the following steps:

[0124] A 3 wt% triethylenetetramine (TETA) aqueous solution was prepared and poured onto the surface of a polysulfone-based flat sheet microfiltration membrane. After immersion for 3 minutes, the remaining TETA aqueous solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the flat sheet microfiltration membrane. A 0.1 wt% MPDI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the above-mentioned flat sheet microfiltration membrane. An interfacial polymerization reaction was carried out for 5 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% MPDI organic solution (hexane as the organic solvent) was used to double-sided dip-coat the formed polyurea selective layer onto the membrane surface for 10 seconds to perform end-sealing treatment, obtaining a treated membrane. The treated membrane was then cleaned with deionized water and placed in a 40°C oven to dry and cure for 5 minutes, thus obtaining the antifouling polyurea composite reverse osmosis membrane (TETA-MPDI membrane). Example 20

[0125] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TETA-TMI membrane) includes the following steps:

[0126] A 1 wt% triethylenetetramine (TETA) aqueous solution was prepared and poured onto the surface of a polyethersulfone (PES) flat sheet microfiltration membrane. After immersion for 3 minutes, the remaining TETA aqueous solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the membrane. A 0.3 wt% TMI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% TMI organic solution (hexane as the organic solvent) was used to double-sided dip-coat the polyurea selective layer onto the membrane surface for 10 seconds for end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (TETA-TMI membrane). Example 21

[0127] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TPTA-PDI membrane) includes the following steps:

[0128] A 2 wt% tetraethylenepentamine (TPTA) aqueous solution was prepared and poured onto the surface of a polyethersulfone (PES) flat sheet microfiltration membrane. After immersion for 5 minutes, the remaining TPTA aqueous solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the membrane. A 0.5 wt% PDI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% PDI organic solution (hexane as the organic solvent) was applied to the polyurea selective layer via slit spraying for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes, yielding the antifouling polyurea composite reverse osmosis membrane (TPTA-PDI membrane). Example 22

[0129] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TPTA-TDI membrane) includes the following steps:

[0130] A 4 wt% tetraethylenepentamine (TPTA) aqueous solution was prepared and poured onto the surface of a polyethersulfone (PES) flat sheet microfiltration membrane. After immersion for 5 minutes, the remaining TPTA aqueous solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the membrane. A 0.3 wt% TDI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 3 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% TDI organic solution (hexane as the organic solvent) was applied to the polyurea selective layer via slit spraying for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes, yielding the antifouling polyurea composite reverse osmosis membrane (TPTA-TDI membrane). Example 23

[0131] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TPTA-MPDI membrane) includes the following steps:

[0132] A 4 wt% tetraethylenepentamine (TPTA) aqueous solution was prepared and poured onto the surface of a polysulfone-based flat sheet microfiltration membrane. After immersion for 5 minutes, the remaining TPTA aqueous solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the flat sheet microfiltration membrane. A 0.1 wt% MPDI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the above-mentioned flat sheet microfiltration membrane. An interfacial polymerization reaction was carried out for 3 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% MPDI organic solution (hexane as the organic solvent) was applied to the surface of the formed polyurea selective layer by slit spraying for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and placed in a 40°C oven to dry and cure for 5 minutes, thus obtaining the antifouling polyurea composite reverse osmosis membrane (TPTA-MPDI membrane). Example 24

[0133] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TPTA-TMI membrane) includes the following steps:

[0134] A 1 wt% tetraethylenepentamine (TPTA) aqueous solution was prepared and poured onto the surface of a polyethersulfone (PES) flat sheet microfiltration membrane. After immersion for 5 minutes, the remaining TPTA aqueous solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the membrane. A 0.2 wt% TMI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% TMI organic solution (hexane as the organic solvent) was applied to the polyurea selective layer via slit spraying for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes, yielding the antifouling polyurea composite reverse osmosis membrane (TPTA-TMI membrane). Example 25

[0135] A method for preparing an antifouling polyurea composite reverse osmosis membrane (PIP-MDI membrane) includes the following steps:

[0136] A 1 wt% piperazine (PIP) aqueous solution was prepared and poured onto the surface of a polyethersulfone (PES) flat sheet microfiltration membrane. After immersion for 5 minutes, the remaining PIP aqueous solution was poured off, and the membrane was allowed to air dry naturally, forming an aqueous phase layer on the surface of the membrane. A 0.2 wt% MDI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% MDI organic solution (hexane as the organic solvent) was applied to the surface of the polyurea selective layer by slit spraying for 10 seconds to perform end-capping treatment, resulting in a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes, yielding an antifouling polyurea composite reverse osmosis membrane (PIP-MDI membrane). Example 26

[0137] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TAE-MDI membrane) includes the following steps:

[0138] A 1 wt% aqueous solution of N,N'-bis(3-aminopropyl)propane-1,3-diamine (TAE) was prepared and poured onto the surface of a polyethersulfone (PES) flat-sheet ultrafiltration membrane. After immersion for 5 minutes, the remaining TAE solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the surface of the membrane. A 0.2 wt% organic solution of MDI (hexane) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% organic solution of MDI (hexane) was applied to the polyurea selective layer via slit spraying for 10 seconds to perform end-sealing treatment. The polyurea selective layer was then immersed in benzene for 5 seconds to obtain the treated membrane. The membrane is then cleaned with deionized water and then dried and cured in a 40°C oven for 5 minutes to obtain the antifouling polyurea composite reverse osmosis membrane (TAE-MDI membrane). Example 27

[0139] A method for preparing an antifouling polyurea composite reverse osmosis membrane (BP-MDI membrane) includes the following steps:

[0140] A 1 wt% aqueous solution of 4,4'-bipiperidine (BP) was prepared and poured onto the surface of a polyethersulfone (PES) flat-sheet ultrafiltration membrane. After immersion for 5 minutes, the remaining BP solution was poured off, and the membrane was allowed to air dry, forming an aqueous phase layer on the membrane surface. A 0.2 wt% organic solution of MDI (hexane) was prepared and poured onto the surface of the aqueous phase layer of the membrane. Interfacial polymerization was carried out for 5 minutes, and the remaining organic solution was removed, forming a polyurea selective layer. Subsequently, a 0.005 wt% organic solution of MDI (hexane) was applied to both sides of the polyurea selective layer for 10 seconds to perform end-sealing treatment. The polyurea selective layer was then rinsed with carbon tetrachloride for 10 seconds to obtain a treated membrane. The treated membrane was then cleaned with deionized water and dried and cured in a 40°C oven for 5 minutes to obtain an antifouling polyurea composite reverse osmosis membrane (BP-MDI membrane). Example 28

[0141] A method for preparing an antifouling polyurea composite reverse osmosis membrane (DETA-MDI membrane) includes the following steps:

[0142] A 1 wt% aqueous solution of diethylenetriamine (DETA) was prepared and poured onto the surface of a hollow fiber microfiltration membrane made of polyethersulfone. After immersion for 5 minutes, the remaining DETA solution was poured off, and the membrane was allowed to air dry naturally, forming an aqueous phase layer on the surface of the hollow fiber microfiltration membrane. A 0.2 wt% organic solution of MDI (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the hollow fiber microfiltration membrane. An interfacial polymerization reaction was carried out for 5 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% organic solution of MDI (hexane as the organic solvent) was applied to the surface of the formed polyurea selective layer by slit spraying for 10 seconds to perform end-capping treatment. The polyurea selective layer was then immersed in dichloroethane for 8 seconds to obtain a treated membrane. The treated membrane was then cleaned with deionized water and placed in a 40°C oven to dry and cure for 5 minutes, thus obtaining the antifouling polyurea composite reverse osmosis membrane (DETA-MDI membrane). Example 29

[0143] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TETA-MDI membrane) includes the following steps:

[0144] A 1 wt% triethylenetetramine (TETA) aqueous solution was prepared and poured onto the surface of a hollow fiber microfiltration membrane made of polyethersulfone. After immersion for 5 minutes, the remaining TETA aqueous solution was poured off, and the membrane was allowed to air dry naturally, forming an aqueous phase layer on the surface of the hollow fiber microfiltration membrane. A 0.2 wt% MDI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the hollow fiber microfiltration membrane. An interfacial polymerization reaction was carried out for 5 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% MDI organic solution (hexane as the organic solvent) was applied to the surface of the formed polyurea selective layer by slit spraying for 10 seconds to perform end-capping treatment. The polyurea selective layer was then immersed in cyclohexane for 6 seconds to obtain a treated membrane. The treated membrane was then cleaned with deionized water and placed in a 40°C oven to dry and cure for 5 minutes, thus obtaining the antifouling polyurea composite reverse osmosis membrane (TETA-MDI membrane). Example 30

[0145] A method for preparing an antifouling polyurea composite reverse osmosis membrane (TPTA-MDI membrane) includes the following steps:

[0146] A 1 wt% tetraethylenepentamine (TPTA) aqueous solution was prepared and poured onto the surface of a hollow fiber microfiltration membrane made of polyethersulfone. After immersion for 5 minutes, the remaining TPTA aqueous solution was poured off, and the membrane was allowed to air dry naturally, forming an aqueous phase layer on the surface of the hollow fiber microfiltration membrane. A 0.2 wt% MDI organic solution (hexane as the organic solvent) was prepared and poured onto the surface of the aqueous phase layer of the hollow fiber microfiltration membrane. An interfacial polymerization reaction was carried out for 5 minutes, and the remaining organic solution was removed to form a polyurea selective layer. Subsequently, a 0.005 wt% MDI organic solution (hexane as the organic solvent) was applied to the surface of the formed polyurea selective layer by slit spraying for 10 seconds to perform end-capping treatment. The polyurea selective layer was then rinsed with petroleum ether for 9 seconds to obtain a treated membrane. The treated membrane was then cleaned with deionized water and placed in a 40°C oven to dry and cure for 5 minutes, thus obtaining the antifouling polyurea composite reverse osmosis membrane (TPTA-MDI membrane). Example 31

[0147] Application of an antifouling polyurea composite reverse osmosis membrane: The antifouling polyurea composite reverse osmosis membrane prepared in Examples 1-30 is used in urban water softening, deep softening of boiler feedwater, brackish water desalination, or seawater desalination.

[0148] Structural morphology characterization

[0149] (I) Morphological characterization by scanning electron microscopy

[0150] The surface morphology of the antifouling polyurea composite reverse osmosis membranes prepared in Examples 1 and 2 was characterized by scanning electron microscopy (SEM), as shown below. Figure 1 and Figure 2 As shown.

[0151] Depend on Figure 1 and Figure 2 As can be seen, the surface of the antifouling polyurea composite reverse osmosis membrane prepared by the present invention is dense and smooth.

[0152] Performance testing

[0153] (a) Separation performance and anti-fouling performance test

[0154] The antifouling polyurea composite reverse osmosis membranes prepared in Examples 1-30 of this invention, as well as the conventional commercial polyamide reverse osmosis membrane (SW30), were tested for separation performance and antifouling performance, respectively.

[0155] The separation performance and antifouling performance of reverse osmosis membranes are characterized by placing the membrane in a standard reverse osmosis test mold and subjecting it to a solution of 2000 ppm NaCl at a temperature of 25°C. o C. Under conditions of pH 6.5-7.5 and pressure 1.55 MPa (225 psi), directly measure the permeate flow rate P (L) and calculate the water flux J (L m) according to the formula J = P / (S x T). -2 h -1 ), where S is the effective membrane area (m²) 2 T is the measurement duration (h). Meanwhile, according to the formula R(%) = (1-C) / (h), T is the measurement duration (h). P / C f ) x100 to calculate the desalination rate, where R is the desalination percentage and C p It is the solute concentration of the permeate, C f It is the solute concentration of the test solution.

[0156] The reverse osmosis membrane was tested under the aforementioned standard membrane performance characterization conditions, and the test results of its separation performance are shown in Table 1. As can be seen from Table 1, the antifouling polyurea composite reverse osmosis membrane of this invention has desalination performance comparable to that of traditional polyamide reverse osmosis membranes, both exhibiting excellent retention performance.

[0157] In addition, a fouling experiment was conducted on the reverse osmosis membrane, in which the concentration of mixed contaminants (BSA / SA / HA + CaCO3 / SiO2) was 1000 ppm, and the test temperature was 25°C. o C. The reverse osmosis membrane was continuously operated for 3 days after contamination. After being removed and washed with deionized water, its basic separation performance was tested, and the test results are shown in Table 1.

[0158] Table 1. Test data on the separation performance and antifouling performance of reverse osmosis membranes.

[0159]

[0160] As can be seen from Table 1, the permeability of the commercial SW30 reverse osmosis membrane can only be maintained at about 14% under 3 days of fouling conditions, indicating that the membrane fouling is extremely serious. In contrast, the antifouling polyurea composite reverse osmosis membrane prepared in Examples 1-30 of this invention can still maintain an irreversible fouling rate of ≤5% and a flux recovery rate (FRR) of ≥95% under the same fouling conditions.

[0161] In summary, the antifouling polyurea composite reverse osmosis membrane prepared by this invention not only has excellent retention performance but also possesses long-lasting antifouling properties, and has broad prospects for industrial applications.

[0162] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing an anti-fouling polyurea composite reverse osmosis membrane, characterized in that, The method comprises the following steps: S1, contacting a support layer with an aqueous solution containing polyamine monomers, and after drying, forming an aqueous phase layer on the support layer; S2, contacting the aqueous phase layer with an organic phase solution containing aromatic polyisocyanate monomers to perform interfacial polymerization, forming a polyurea selective layer; S3, performing end-capping treatment on the polyurea selective layer, and then performing cleaning and drying and solidification, thereby obtaining the anti-pollution polyurea composite reverse osmosis membrane.

2. The method for preparing an antifouling polyurea composite reverse osmosis membrane as described in claim 1, characterized in that, In step S1, the aqueous solution contains a surfactant; and / or, the mass concentration of the surfactant in the aqueous solution is 0.1wt%-0.5wt%; and / or The surfactant is at least one of sodium dodecyl sulfate, sodium laureth sulfate, polysorbate 80, and polyvinyl alcohol.

3. The method for preparing an antifouling polyurea composite reverse osmosis membrane as described in claim 1, characterized in that, In step S1, the polyamine monomer is at least one of piperazine, 4,4'-dipiperidine, N,N'-bis(3-aminopropyl)propane-1,3-diamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; and / or, the mass concentration of the polyamine monomer in the aqueous solution is 0.1wt%-5wt%; and / or The support layer is one of a flat microfiltration membrane, a flat ultrafiltration membrane, a hollow fiber microfiltration membrane, or a hollow fiber ultrafiltration membrane; and / or, the material of the support layer is selected from polyvinylidene fluoride, polyacrylonitrile, polysulfone, polyethersulfone, or polyimide; and / or The contacting time is 0.5min-5min; and / or The drying method is natural air drying after removing the residual liquid on the surface of the support layer.

4. The method for preparing an antifouling polyurea composite reverse osmosis membrane as described in claim 1, characterized in that, In step S2, the aromatic polyisocyanate monomer is at least one of 1,3-diisocyanate and its derivatives, toluene diisocyanate and its derivatives, methyldiphenyl diisocyanate and its derivatives, 1,3,5-triisocyanate and its derivatives, and diphenylmethane diisocyanate and its derivatives; and / or The organic solvent in the organic phase solution is a single solvent system or a co-solvent system; and / or The single solvent system is one of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, or xylene; and / or The co-solvent system is a mixed solution of a weak polar solvent and a medium-strong polar solvent; and / or The weak polar solvent is one of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene, or xylene, and the medium-strong polar solvent is one of methanol, ethanol, isopropyl alcohol, dichloromethane, trichloromethane, or ethyl acetate; and / or The volume percentage of the medium-strong polar solvent in the co-solvent system is 1%-80%.

5. The method for preparing an antifouling polyurea composite reverse osmosis membrane as described in claim 1, characterized in that, In step S2, the mass concentration of the aromatic polyisocyanate monomer in the organic phase solution is 0.01wt%-1.0wt%; and / or The interfacial polymerization time is 0.5min-5min; and / or The contacting method is single-sided dip coating, double-sided dip coating, or slit spraying.

6. The method for preparing an antifouling polyurea composite reverse osmosis membrane as described in claim 1, characterized in that, In step S3, before the end-capping treatment, the excess organic phase solution on the surface of the polyurea selective layer is removed; and / or The end-closing treatment is performed by contacting an organic phase solution containing aromatic polyisocyanate monomers or an acyl chloride organic solution with the polyurea selective layer; and / or the contacting time is 10s-120s; and / or the contacting method is single-sided dip coating, double-sided dip coating or slit spraying; and / or The mass concentration of the aromatic polyisocyanate monomers in the organic phase solution is 0.005wt%-0.2wt%; and / or The mass concentration of the acyl chloride in the acyl chloride organic solution is 0.005wt%-0.2wt%; and / or The organic solvent in the organic phase solution and the acyl chloride organic solution is one of petroleum ether, n-hexane, cyclohexane, n-heptane, n-decane, n-dodecane, toluene or xylene.

7. The method for preparing an antifouling polyurea composite reverse osmosis membrane as described in claim 1, characterized in that, In step S3, after the end-closing treatment, the polyurea selective layer is soaked or washed with a non-polar solvent for 5s-10s, and then cleaned and dried and solidified; and / or The non-polar solvent is one of benzene, carbon tetrachloride, dichloroethane, cyclohexane or petroleum ether.

8. The method for preparing an antifouling polyurea composite reverse osmosis membrane as described in claim 1, characterized in that, In step S3, the cleaning is performed by using deionized water; and / or The drying and solidification temperature is 40℃-80℃, and the drying and solidification time is 5min-60min.

9. An antifouling polyurea composite reverse osmosis membrane, characterized in that, The anti-pollution polyurea composite reverse osmosis membrane is prepared by the method of any one of claims 1-8.

10. Use of an anti-fouling polyurea composite reverse osmosis membrane, characterized in that, The anti-pollution polyurea composite reverse osmosis membrane of claim 9 or prepared by the method of any one of claims 1-8 is applied in city water softening, boiler make-up water deep softening, brackish water desalination or seawater desalination.

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