Reverse osmosis membrane

Abstract

The reverse osmosis membrane comprises a supporting layer, a transition layer, a composite functional layer and a separation layer which are sequentially arranged, the supporting layer provides mechanical strength and a water permeable channel, the transition layer enhances the binding force of the supporting layer and the composite functional layer, and the composite functional layer provides a separation channel to intercept heavy metal ions. And the separation layer realizes separation of salt and water. According to the technical scheme, the separation layer achieves separation of salt and water, the composite functional layer provides a separation channel to intercept heavy metal ions to achieve a separation type filtering system of sodium salt and the heavy metal ions, the surface flatness is optimized through the transition layer, and the binding force between the supporting layer and the composite functional layer is increased.

Description

A reverse osmosis membrane Technical Field

[0001] This invention relates to the field of membranes, and more specifically, to a reverse osmosis membrane. Background Technology

[0002] The global water shortage is a prominent issue, and seawater desalination is a crucial solution. my country's coastal areas have an urgent need for seawater desalination, and reverse osmosis (RO) membranes have already achieved large-scale application. The separation performance of these membranes relies on the synergistic effect of multiple processes. However, limitations in materials and processes result in bottlenecks where it is difficult to simultaneously achieve high desalination rates and high ion selectivity, thus restricting application efficiency. While the dense structure of existing RO membranes improves desalination rates, it also weakens ion selectivity, leading to insufficient removal efficiency for calcium, magnesium, and heavy metal ions such as lead and cadmium. Therefore, there is an urgent need for a RO membrane that can achieve both high desalination rates and high ion removal efficiency. Summary of the Invention

[0003] The present invention aims to provide a reverse osmosis membrane to solve the problem that high desalination rate and high ion removal rate cannot be achieved simultaneously in the prior art.

[0004] To achieve the above objectives, according to one aspect of the present invention, a reverse osmosis membrane is provided, comprising a support layer, a transition layer, a composite functional layer and a separation layer arranged sequentially, wherein the support layer provides mechanical strength and water permeability channels, the transition layer enhances the bonding force between the support layer and the composite functional layer, the composite functional layer provides separation channels to trap heavy metal ions, and the separation layer achieves the separation of salt and water.

[0005] Furthermore, the support layer is a polyethersulfone membrane or a polysulfone membrane, with a thickness of 80-150 μm, a pore size distribution of 0.1-0.5 μm, and a porosity of 40-70%.

[0006] Furthermore, the support layer is prepared by phase inversion method, and the casting solution consists of 15-18 wt% polymer, 4-5 wt% polyvinylpyrrolidone and 77-81 wt% dimethylformamide.

[0007] Furthermore, the transition layer is an aminosilane coupling agent modified silica sol layer. The sol layer is prepared by mixing tetraethyl orthosilicate, ethanol, and deionized water in a volume ratio of 1:3-4:2, adjusting the pH value to 4-6, adding 3-5wt% aminosilane coupling agent, and hydrolyzing at 45-50℃ for 3-4 hours. After the support layer is dipped into the sol, it is baked at 85-90℃ for 45-50 minutes to cure and obtain the sol layer. The thickness of the transition layer is 5-10μm.

[0008] Furthermore, the composite functional layer is formed by placing a support layer-transition layer composite structure in a vacuum filtration device, adding a suspension, filtering for 30 seconds under a vacuum range of -0.08 to -0.1 MPa, and drying in a 60-80℃ drying oven for 10-15 minutes. The suspension is prepared by dispersing nanocellulose, zinc oxide, and hydroxylated modified graphene oxide in deionized water and ultrasonically treating for 30-60 minutes. The suspension concentration is: nanocellulose 0.8 mg / ml, zinc oxide 0.2 mg / ml, and hydroxylated modified graphene oxide 0.1-0.2 mg / ml.

[0009] Furthermore, the zinc oxide particles have a diameter of 10-20 nm, and the hydroxylated modified graphene oxide has a surface area of ​​200-500 m². 2 / g, oxygen-containing functional group content 15-25%, composite functional layer thickness 30-50nm.

[0010] Furthermore, the separation layer is a modified polyamide separation layer with a thickness of 100-300 nm. The surface of the separation layer has a nanoscale corrugated structure. The separation layer is formed by interfacial polymerization of aqueous monomers and organic monomers. The aqueous monomers include piperazine and m-phenylenediamine, and the organic monomer is pyromellitic trimethylol chloride.

[0011] Furthermore, the molar ratio of piperazine to m-phenylenediamine in the aqueous phase monomer is 1:0.5-1:2, the total concentration is 1.5-2.5 wt%, the concentration of organic phase monomer is 0.1-0.3 wt%, the interfacial polymerization temperature is 40-70℃, the reaction time is 60-120 seconds, after interfacial polymerization, the mixture is heat-treated at 90-120℃ for 3-8 minutes, and then surface modified with 0.01-1% amino-terminated polysiloxane solution for 1-10 minutes.

[0012] The technical solution of the present invention includes a support layer, a transition layer, a composite functional layer and a separation layer arranged sequentially. The separation layer realizes the separation of salt and water, the composite functional layer provides a separation channel to intercept heavy metal ions to realize a separation filtration system for sodium salt and heavy metal ions, and the transition layer optimizes the surface smoothness and increases the bonding force between the support layer and the composite functional layer. Attached Figure Description

[0013] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0014] Figure 1 shows a schematic diagram of zinc oxide particles in the composite functional layer of the reverse osmosis membrane according to the present invention; and

[0015] Figure 2 shows a schematic diagram of the reverse osmosis membrane in Figure 1. Detailed Implementation

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0017] Referring to Figures 1 and 2, the present invention provides a reverse osmosis membrane, comprising a support layer 11, a transition layer 12, a composite functional layer 13, and a separation layer 14 arranged sequentially. The support layer 11 provides mechanical strength and water permeability channels, the transition layer 12 enhances the bonding force between the support layer 11 and the composite functional layer 13, the composite functional layer 13 provides separation channels to trap heavy metal ions, and the separation layer 14 achieves the separation of salt and water.

[0018] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: the separation layer 14 realizes the separation of salt and water, the composite functional layer 13 provides a separation channel to intercept heavy metal ions to realize a separation filtration system of sodium salt and heavy metal ions, the transition layer 12 optimizes the surface flatness, and increases the bonding force between the support layer 11 and the composite functional layer 13 to prevent interlayer separation.

[0019] In this embodiment, the support layer 11 is selected as a polyethersulfone membrane or a polysulfone membrane, which can provide mechanical strength and water permeability channels for the reverse osmosis membrane. The support layer 11 can be prepared by phase inversion method. The casting solution consists of 15-18 wt% polymer, 4-5 wt% polyvinylpyrrolidone, and 77-81 wt% dimethylformamide. The casting solution is coated onto a nonwoven fabric with a doctor blade gap of 0.18-0.2 mm and a doctor blade speed of 1.0-2.0 m / s. The coated membrane is immersed in a deionized water coagulation bath at 25-30℃, and the phases separate to form a membrane. The membrane is washed with water for 20-24 hours to remove residual solvent and dried at 75-80℃ for 2-3 hours to obtain a support layer 11 membrane with a thickness of 80-150 μm, a pore size distribution of 0.1-0.5 μm, and a porosity of 40-70%.

[0020] Test Example 1

[0021] With a support layer 11 thickness of 80 μm and a pore size of 0.1 μm, the porosity is 40%. At this point, the mechanical strength of the support layer 11 is measured to be 2.8 MPa, and the water permeability is 550 L / (m²). 2 The mechanical strength is less than 2.5 MPa (·h·MPa), which meets the requirements for membrane operation. However, when the thickness of the support layer 11 is less than 80 μm, the mechanical strength is less than 2.5 MPa, which is insufficient for membrane operation.

[0022] Test Example 2

[0023] When the thickness of the support layer 11 is 150 μm and the pore size is 0.5 μm, the porosity is 70%. At this point, the mechanical strength of the support layer 11 is measured to be 3.5 MPa, and the water permeability is 480 L / (M2·h·MPa), which meets the requirements for membrane operation. When the thickness of the support layer 11 exceeds 150 μm, the water permeability decreases, affecting the flux. Increasing the porosity further would lead to a loose structure, failing to meet the membrane operation requirements.

[0024] Test Example 3

[0025] When the thickness of the support layer 11 is 120 μm and the polymer content is 16.5 wt%, a support layer 11 with a pore size of 0.25-0.3 μm and a porosity of 54% is obtained. At this time, the mechanical strength of the support layer 11 is measured to be 3.2 MPa and the water permeability is 515 L / (M2·h·MPa), which meets the requirements for membrane operation.

[0026]

[0027] The polymer content determines the pore size. When the polymer content is 15 wt%, the pore size is 0.4-0.5 μm; when the polymer content is 18 wt%, the pore size is 0.1-0.25 μm. When the thickness of the support layer 11 is less than 80 μm, the mechanical strength is too low to meet the mechanical strength required for membrane operation. When the thickness of the support layer 11 is greater than 150 μm, the water permeability decreases, affecting the flux and failing to meet the membrane operation requirements. Furthermore, further increasing the porosity will lead to a loose structure, which will also fail to meet the membrane operation requirements.

[0028] In this embodiment, the transition layer 12 is a silica sol layer modified with an aminosilane coupling agent. The sol layer is prepared by mixing tetraethyl orthosilicate, ethanol, and deionized water at a volume ratio of 1:3-4:2, adjusting the pH to 4-6, adding 3-5 wt% aminosilane coupling agent, and hydrolyzing at 45-50°C for 3-4 hours. The support layer 11 is then coated with the sol and cured by baking at 85-90°C for 45-50 minutes to obtain the support layer 11 with the transition layer 12. The thickness of the transition layer 12 is 5-10 μm, and the surface roughness Ra < 50 nm. The aminosilane coupling agent can be γ-aminopropyltriethoxysilane (KH550) or γ-glycidoxypropyltrimethoxysilane (KH540).

[0029] Test Example 4

[0030] When preparing the sol, the volume ratio of tetraethyl orthosilicate, ethanol, and deionized water was 1:3:2, the content of aminosilane coupling agent was 3wt%, the pH value was 4, the surface roughness Ra of the resulting transition layer 12 was 45nm, the interlayer bonding force was 3N, the curing thickness was 5μm, the peeling rate between the transition layer 12 and the composite functional layer 13 was 0.8%, the hydrolysis efficiency was 85%, the density of the transition layer 12 was moderate, and the effect on water flux was negligible.

[0031] Test Example 5

[0032] When preparing the sol, the volume ratio of tetraethyl orthosilicate, ethanol, and deionized water was 1:4:2, the content of aminosilane coupling agent was 5wt%, the pH value was 6, the surface roughness Ra of the resulting transition layer 12 was 35nm, the interlayer bonding force was 3.6N, the curing thickness was 10μm, the peeling rate between the transition layer 12 and the composite functional layer 13 was 0.3%, the hydrolysis efficiency was 88%, the density of the transition layer 12 was moderate, and the effect on water flux was negligible.

[0033] Test Example 6

[0034] When preparing the sol, the volume ratio of tetraethyl orthosilicate, ethanol, and deionized water was 1:3.5:2, the content of aminosilane coupling agent was 4wt%, the pH value was 5, the surface roughness Ra of the resulting transition layer 12 was 38nm, the interlayer bonding force was 3.5N, the curing thickness was 8μm, the peeling rate between the transition layer 12 and the composite functional layer 13 was 0.6%, the hydrolysis efficiency was 87.3%, the density of the transition layer 12 was moderate, and the effect on water flux was negligible.

[0035]

[0036] When preparing the sol, the lower the ethanol ratio, the higher the sol viscosity. When the volume ratio is below 1:3:2, the lower limit of the coating thickness is less than 5μm, the surface roughness Ra>50, and the interlayer bonding force is reduced to below 3N, posing a risk of delamination. The higher the ethanol ratio, the better the sol dispersion, the smoother the surface, the upper limit of the thickness is 10μm, and the bonding force is improved. When the aminosilane coupling agent content is below 3wt%, the peeling rate is greater than 1%, and delamination is possible. When the aminosilane coupling agent content is above 5wt%, the agglomeration reaction will not occur due to excess. At pH 4, the hydrolysis reaction is sufficient but not violent, avoiding silica sol agglomeration and ensuring that the transition layer 12 is not blocked. At pH 6, the hydrolysis rate is stable, and the surface smoothness of the transition layer 12 is slightly better. pH=4 does not affect the loading of the subsequent composite functional layer 13. If the pH is too low, the hydrolysis reaction is insufficient, and the silica sol will agglomerate. If the pH is too high, the hydrolysis reaction rate will decrease, affecting the loading of the subsequent composite functional layer 13.

[0037] The composite functional layer 13 is prepared by preparing a suspension. The suspension is formed by dispersing nanocellulose, zinc oxide, and hydroxylated modified graphene oxide in deionized water and ultrasonically treating for 30-60 minutes. The concentration of the suspension is 0.8 mg / ml for nanocellulose, 0.2 mg / ml for zinc oxide, and 0.1-0.2 mg / ml for hydroxylated modified graphene oxide. The composite structure of support layer 11-transition layer 12 is placed in a vacuum filtration device, the suspension is added, and filtration is performed for 30 seconds under a vacuum range of -0.08 to -0.1 MPa. After drying in a 60-80℃ drying oven for 10-15 minutes, the composite functional layer 13 is formed. The zinc oxide particles in the composite functional layer 13 have a particle size of 10-20 nm, and the surface area of ​​the hydroxylated modified graphene oxide is 200-500 m². 2 The composite functional layer 13 has a thickness of 30-50 nm. In the composite functional layer 13, the mass ratio of nanocellulose to zinc oxide is 4:1. Nanocellulose constructs hydrophilic nanopores, promoting rapid water molecule transport while repelling negatively charged salt ions. Zinc oxide provides photocatalytic self-cleaning functionality, generating •OH free radicals under light irradiation to decompose organic pollutants adsorbed on the membrane surface, reducing contamination. This allows the composite functional layer 13 to simultaneously achieve high water flux and high antifouling properties. Hydroxylated modified graphene oxide accounts for 0.5-1% of the total mass; too low a percentage prevents the formation of an effective network, while too high a percentage leads to pore blockage. Zinc oxide and hydroxylated modified graphene oxide optimize the pore structure, improve water molecule selectivity, enhance membrane surface hydrophilicity, and synergistically enhance overall stability with ZnO. The zinc oxide nanoparticles have a particle size of 10-20 nm; smaller particles tend to aggregate, while larger particles have a small specific surface area and low adsorption efficiency.

[0038] Separation layer 14 is a modified polyamide separation layer with a thickness of 100-300 nm. Separation layer 14 is formed by interfacial polymerization of aqueous and organic monomers. The aqueous monomers include piperazine and m-phenylenediamine, and the organic monomer is trimesoyl chloride. The molar ratio of piperazine to m-phenylenediamine in the aqueous monomers is 1:0.5-1:2, with a total concentration of 1.5-2.5 wt%, and the concentration of the organic monomers is 0.1-0.3 wt%. The interfacial polymerization temperature is 40-70℃, and the reaction time is 60-120 seconds. After interfacial polymerization, the mixture is heat-treated at 90-120℃ for 3-8 minutes, followed by surface modification with a 0.01-1% terminal amino polysiloxane solution for 1-10 minutes. The surface of separation layer 14 has a nanoscale corrugated structure after interfacial polymerization, which increases the effective separation area and improves water flux. Piperazine improves the flexibility of the cross-linked network and increases water molecule channels; m-phenylenediamine ensures sufficient cross-linking density and maintains a high desalination rate.

[0039] Example 1

[0040] The support layer 11 is 80 μm thick with a porosity of 40%; the transition layer is 125 μm thick, and the solution is prepared with tetraethyl orthosilicate, ethanol, and deionized water in a volume ratio of 1:3:2, containing 3 wt% aminosilane coupling agent and a pH of 4; the composite functional layer is 1330 nm thick, containing 0.1 mg / ml of hydroxylated modified graphene oxide, with zinc oxide particles of 10 nm in diameter, and the hydroxylated modified graphene oxide has a surface area of ​​200 m². 2 / g, oxygen-containing functional group content 15%; separation layer 14100nm, total monomer concentration in aqueous phase 1.5 wt%, monomer concentration in organic phase 0.1 wt%, the desalination rate was measured to be 99.3%; heavy ion removal rate 99.2%; water flux 44LMH; interlayer bonding force 3.0N; 1000-hour decay rate 5.7%.

[0041] Example 2

[0042] The support layer 11 has a diameter of 150 μm and a porosity of 70%. The transition layer 12 has a diameter of 110 μm. The solution is prepared with tetraethyl orthosilicate, ethanol, and deionized water in a volume ratio of 1:4:2, with an aminosilane coupling agent content of 5 wt% and a pH value of 6. The composite functional layer has a diameter of 1350 nm, a hydroxylated modified graphene oxide content of 0.2 mg / ml, a zinc oxide particle size of 20 nm, and a hydroxylated modified graphene oxide surface area of ​​500 m². 2 / g, oxygen-containing functional group content 25%; separation layer 14300nm, total monomer concentration in aqueous phase 2.5 wt%, monomer concentration in organic phase 0.3 wt%, the desalination rate was measured to be 99.9%; heavy ion removal rate 99.8%; water flux 40LMH; interlayer bonding force 3.8N; 1000-hour decay rate 4.5%.

[0043] Example 3

[0044] The support layer 11 has a thickness of 120 μm and a porosity of 55%; the transition layer has a thickness of 128 μm, and the solution is prepared with tetraethyl orthosilicate, ethanol, and deionized water in a volume ratio of 1:3.5:2, an aminosilane coupling agent content of 4 wt%, and a pH value of 5; the composite functional layer has a thickness of 1340 nm, a hydroxylated modified graphene oxide content of 0.15 mg / ml, zinc oxide particles with a particle size of 15 nm, and a hydroxylated modified graphene oxide surface area of ​​350 m². 2 / g, oxygen-containing functional group content 18%; separation layer 14200nm, total monomer concentration in aqueous phase 2 wt%, monomer concentration in organic phase 0.2 wt%, the desalination rate was measured to be 99.8%; heavy ion removal rate 99.7%; water flux 42.5 LMH; interlayer bonding force 3.5 N; 1000-hour decay rate 4.9%.

[0045]

[0046] Comparative experiment

[0047] Performance testing conditions: temperature 25℃, pressure 3.2MPa, solute 32000mg / L NaCl + 5mg / L Cd 2+ +1μm particles.

[0048] The membrane parameters used are those of the reverse osmosis membrane in Example 3: support layer 11, thickness 120 μm; transition layer 12, thickness 8 μm; composite functional layer 13, thickness 40 nm; and separation layer 14, thickness 200 nm.

[0049] Test results: The reverse osmosis membrane of this application has the following characteristics: desalination rate: 99.8%; heavy ion removal rate: 99.7%; particulate removal rate: 99.8%; water flux: 42.5 LMH; flux decay rate after 100 hours: 14.5%; performance decay rate after 1000 hours: 4.9%; interfacial bonding force: 3.5 N; structural stability: no delamination, long-term stable operation.

[0050] Control group 1 (without composite functional layer 13)

[0051] Support layer 11 + transition layer 12 + separation layer 14

[0052] Test results: Desalination rate: 99%; Heavy ion removal rate: 96%; Particulate removal rate: 96.5%; Water flux: 34.2 LMH; 100-hour flux decay rate: 38.5%; 1000-hour performance decay rate: 16.8%; Structural stability: No stratification, but significant performance decay.

[0053] It is evident that removing the composite functional layer 13 weakens the adsorption capacity of heavy metal ions and limits the ability of the pores to intercept particles.

[0054] Control group 2 (single functional layer, containing only nanocellulose and zinc oxide)

[0055] Test results: Desalination rate: 99.2%; Heavy ion removal rate: 98.5%; Particulate removal rate: 98.8%; Water flux: 39.8 LMH; 100-hour flux decay rate: 15.7%; 1000-hour performance decay rate: 5.3%; Structural stability: No stratification, stability is average.

[0056] It is evident that the lack of hydroxylated modified graphene oxide results in insufficient synergistic adsorption of heavy ions, while inadequate optimization of the pore structure leads to a decrease in the ability to intercept particles.

[0057] Control group 3 (without aminosilane-modified transition layer 12)

[0058] Test results: Desalination rate: Initially 99.0%, then plummeted to 98.2% after 300 hours; Heavy ion removal rate: 95.5%; Particulate removal rate: 96%; Water flux: 33.8 LMH; Flux decay rate after 100 hours: 39.2%; Performance decay rate after 1000 hours: Delamination occurred after 300 hours, rendering it unusable; Interfacial bonding force: <1.5 N; Structural stability: Delamination occurred after 300 hours, rendering it unusable.

[0059] It is evident that the lack of the transition layer 12 and the unmodified interlayer adsorption system lead to a decrease in heavy ion absorption capacity. Furthermore, the instability of the transition layer 12 affects the overall interception effect on particles. The poor interlayer bonding results in a slightly lower flux base. The susceptibility of the transition layer 12 to fouling leads to easy penetration of contaminants. The weak interlayer bonding of the unmodified transition layer 12 causes stratification during operation.

[0060] Control group 4 (conventional membrane)

[0061] The control group had the following four test conditions: temperature 25℃, pressure 3.2MPa, and solute 32000mg / LNaCl.

[0062] The test results are as follows: desalination rate: 99.8%; heavy ion removal rate: not tested; particulate removal rate: not tested; water flux: 28.5 LMH; 100-hour flux decay rate: 42.3%; 1000-hour performance decay rate: 18.5%; structural stability: no stratification, poor anti-fouling properties lead to rapid performance decay.

[0063] It can be seen that the reverse osmosis membrane of the present invention is superior to the control group 4 in both stability and water flux.

[0064]

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A reverse osmosis membrane, characterized in that, The reverse osmosis membrane comprises a support layer (11), a transition layer (12), a composite functional layer (13), and a separation layer (14) arranged sequentially. The support layer (11) provides mechanical strength and water permeability channels. The transition layer (12) enhances the bonding force between the support layer (11) and the composite functional layer (13). The composite functional layer (13) provides separation channels to trap heavy metal ions. The separation layer (14) achieves the separation of salt and water.

2. The reverse osmosis membrane according to claim 1, characterized in that, The support layer (11) is a polyethersulfone film or a polysulfone film. The support layer (11) has a thickness of 80-150 μm, a pore size distribution of 0.1-0.5 μm, and a porosity of 40-70%.

3. The reverse osmosis membrane according to claim 2, characterized in that, The support layer (11) is prepared by phase inversion method, and the casting solution is composed of 15-18 wt% polymer, 4-5 wt% polyvinylpyrrolidone and 77-81 wt% dimethylformamide.

4. The reverse osmosis membrane according to claim 3, characterized in that, The transition layer (12) is an aminosilane coupling agent modified silica sol layer. The sol layer is prepared by mixing tetraethyl orthosilicate, ethanol and deionized water in a volume ratio of 1:3-4:2, adjusting the pH value to 4-6, adding 3-5wt% aminosilane coupling agent, and hydrolyzing at 45-50℃ for 3-4 hours. The support layer (11) is dipped into the sol and then baked at 85-90℃ for 45-50 minutes to cure the sol layer. The thickness of the transition layer (12) is 5-10μm.

5. The reverse osmosis membrane according to claim 1, characterized in that, The composite functional layer (13) is formed by placing a support layer (11)-transition layer (12) composite structure in a vacuum filtration device, adding a suspension, filtering for 30 seconds under a vacuum range of -0.08 to -0.1 MPa, and drying in a drying oven at 60-80℃ for 10-15 minutes. The suspension is prepared by dispersing nanocellulose, zinc oxide and hydroxylated modified graphene oxide in deionized water and ultrasonically treating for 30-60 minutes. The concentration of the suspension is: nanocellulose 0.8 mg / ml, zinc oxide 0.2 mg / ml, and hydroxylated modified graphene oxide 0.1-0.2 mg / ml.

6. The reverse osmosis membrane according to claim 5, characterized in that, The zinc oxide particles have a particle size of 10-20 nm, and the hydroxylated modified graphene oxide has a surface area of ​​200-500 m². 2 / g, oxygen-containing functional group content 15-25%, the composite functional layer (13) thickness is 30-50nm.

7. The reverse osmosis membrane according to claim 1, characterized in that, The separation layer (14) is a modified polyamide separation layer (14), the thickness of the separation layer (14) is 100-300nm, the surface of the separation layer (14) has a nanoscale corrugated structure, the separation layer (14) is formed by interfacial polymerization of aqueous monomer and organic monomer, the aqueous monomer contains piperazine and m-phenylenediamine, and the organic monomer is pyromellitic chloride.

8. The reverse osmosis membrane according to claim 7, characterized in that, The molar ratio of piperazine to m-phenylenediamine in the aqueous phase monomer is 1:0.5-1:2, and the total concentration is 1.5-2.5 wt%. The concentration of the organic phase monomer is 0.1-0.3 wt%. The interfacial polymerization temperature is 40-70℃, and the reaction time is 60-120 seconds. After the interfacial polymerization, the mixture is heat-treated at 90-120℃ for 3-8 minutes, and then surface-modified with a 0.01-1% amino-terminated polysiloxane solution for 1-10 minutes.

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