An integrated graphene oxide reverse osmosis membrane with sub-nanometer carbon tubes and a preparation method thereof

Abstract

The application discloses an integrated sub-nanometer carbon tube graphene oxide reverse osmosis membrane and a preparation method thereof. The reverse osmosis membrane comprises a sub-nanometer carbon tube, a graphene oxide layer and a phospholipid bilayer, the phospholipid bilayer is loaded with the sub-nanometer carbon tube and an integrin, the graphene oxide layer is surface-modified with an anti-adhesion polypeptide, the integrin is bonded with the anti-adhesion polypeptide, the anchoring of the graphene oxide and the phospholipid bilayer is realized, the graphene oxide layer has graphene oxide layer pores and graphene oxide layer interlayer channels, and the phospholipid bilayer is encapsulated in the graphene oxide layer interlayer channels. The reverse osmosis membrane has superior desalination performance, high structural stability and certain pretreatment effect. In the reverse osmosis process, water molecules can quickly pass through, and salt ions cannot pass through, so that high water flux and high desalination rate seawater desalination are realized, and the commercial application purpose of the reverse osmosis membrane seawater desalination is achieved.

Description

Technical Field

[0001] This invention relates to the field of reverse osmosis composite membranes, specifically to a graphene oxide reverse osmosis membrane with integrated sub-nano carbon nanotubes and its preparation method. Background Technology

[0002] As is well known, seawater reserves are abundant, and seawater desalination has become the most effective solution to the shortage of freshwater resources. Currently, seawater desalination technology mainly uses reverse osmosis. Under pressure, water molecules in seawater pass through a reverse osmosis membrane, while salt ions cannot, thus achieving seawater desalination. The performance of the reverse osmosis membrane plays a decisive role; water flux and desalination rate are key performance indicators. Increasing water flux can reduce energy consumption, and increasing the desalination rate can improve water quality.

[0003] Currently widely used traditional reverse osmosis membranes are mainly made of cellulose acetate, polyamide, and polyimide. These membranes have long and tortuous pores, significantly slowing down water molecule transport. Furthermore, the non-uniform pore size drastically reduces the desalination rate. Traditional reverse osmosis membranes suffer from a severe trade-off between water flux and desalination rate; that is, increasing the desalination rate is accompanied by a decrease in water flux. This trade-off has become a bottleneck limiting the performance improvement of traditional reverse osmosis membranes. Typically, achieving the target desalination rate requires a significant loss of water flux.

[0004] Carbon nanotubes (CNTs) possess excellent mechanical properties and superior potential for functional group modification. Their water molecule transport capacity is comparable to that of aquaporins, making them a promising candidate for preparing novel reverse osmosis membranes. The commonly used method is to grow vertically oriented CNT arrays via chemical vapor deposition (CVD) and then fill them with ceramics or polymers to prepare CNT reverse osmosis membranes. However, in this method, the diameter of the CNTs is typically greater than 1 nm and their uniformity is poor, severely affecting the membrane's desalination rate. Furthermore, the low porosity of the CNTs on the membrane makes it difficult to increase the water flux. In 2017, Professor Aleksandr Noy of Lawrence Livermore National Laboratory reported in Science a sub-nano-carbon nanotube fabricated using ultrasonic cutting. These nanotubes, approximately 0.8 nm in diameter and 10 nm in length, exhibited uniform size and could spontaneously insert into the phospholipid bilayer to form transmembrane channels, demonstrating excellent water molecule transport capacity, but their desalination capacity remained insufficient. In addition, the phospholipid bilayer is very fragile and cannot maintain the driving pressure in the reverse osmosis process, so its integrated carbon nanotube reverse osmosis membrane cannot be used for commercial purposes.

[0005] Graphene oxide is another promising candidate for novel reverse osmosis membranes. Graphene oxide consists of stable, stacked two-dimensional sheet-like structures with smooth surfaces and nanoscale interlayer channels. Its surface is covered with numerous oxygen-containing functional groups, such as hydroxyl, carboxyl, and epoxy groups. In 2017, Professor Rahul Raveendran Nair of the University of Manchester reported in Nature Nanotechnology that using stacked graphene oxide for seawater desalination achieved high water flux and desalination rates. However, after prolonged immersion in water, the interlayer spacing of graphene oxide tends to expand, leading to a significant decrease in desalination rate. This expansion problem limits its application in seawater desalination.

[0006] Therefore, the development of new reverse osmosis membranes is imperative to further reduce the cost of seawater desalination. Summary of the Invention

[0007] To address the aforementioned technical shortcomings, the present invention aims to provide an integrated sub-nano carbon nanotube graphene oxide reverse osmosis membrane and its preparation method. This membrane exhibits superior desalination performance, high structural stability, and a certain pretreatment effect. During the reverse osmosis process, water molecules can pass through rapidly, while salt ions cannot, achieving high water flux and high desalination rate seawater desalination, thus fulfilling the commercial application objective of reverse osmosis membrane seawater desalination.

[0008] The researchers of this invention believe that carbon nanotubes have excellent mechanical properties and superior potential for functional group modification. Sub-nanocarbon nanotubes can spontaneously insert into the phospholipid bilayer to form transmembrane channels, exhibiting excellent water molecule transport capabilities. However, the phospholipid bilayer is very fragile and difficult to maintain the driving pressure during the reverse osmosis process. Therefore, it is necessary to further improve the desalination capacity of sub-nanocarbon nanotubes. Furthermore, if a substrate can be designed to combine with the phospholipid bilayer and protect it, it will be possible to effectively integrate these sub-nanocarbon nanotubes to prepare reverse osmosis membranes.

[0009] Graphene oxide is composed of stable, stacked two-dimensional sheet-like structures with a smooth surface and nanoscale interlayer channels. Its surface is covered with numerous oxygen-containing functional groups, such as hydroxyl, carboxyl, and epoxy groups. While the expansion problem of graphene oxide limits its application in seawater desalination, this invention suggests that it could also provide space for phospholipid bilayers and similar materials.

[0010] Therefore, in order to solve the existing technical problems, the present invention adopts the following technical solution:

[0011] The first objective of this invention is to provide an integrated sub-nanocarbon nanotube graphene oxide reverse osmosis membrane, comprising sub-nanocarbon nanotubes, a graphene oxide layer, and a phospholipid bilayer. The phospholipid bilayer is loaded with sub-nanocarbon nanotubes and an integrase protein. The surface of the graphene oxide layer is modified with an anti-adhesion peptide. The integrase protein is bonded to the anti-adhesion peptide to anchor the graphene oxide and phospholipid bilayer. The graphene oxide layer has graphene oxide pores and interlayer channels, and the phospholipid bilayer is encapsulated within the interlayer channels of the graphene oxide.

[0012] Furthermore, the end functional groups of the sub-nano carbon nanotubes include neutral methylamine functional groups, positively charged ethylenediamine functional groups, or negatively charged carboxyl functional groups. The sub-nano carbon nanotubes, through the hydrophilic functional groups modified at the ends, attract each other with the hydrophobic tube wall in the middle and the head hydrophilic groups and the inner hydrophobic groups of the phospholipid bilayer, respectively, so that the carbon nanotubes can spontaneously insert into the phospholipid bilayer.

[0013] Another object of the present invention is a method for preparing a graphene oxide reverse osmosis membrane integrating sub-nano carbon nanotubes, comprising the following steps:

[0014] S1: Mix single-walled carbon nanotube raw materials with pure water to 0.11-0.13 mg / mL, and add phospholipid molecules to 3.4-3.6 mg / mL. Ultrasonically cut the long carbon nanotubes in a constant temperature oven at 28-35℃ for 12-20 hours.

[0015] S2: Centrifuge the above mixture at 10000-12000 rpm for 1-2 h to remove unbroken carbon nanotubes and impurities, and obtain a solution of sub-nano carbon nanotubes wrapped with phospholipid molecules. The ends of the carbon nanotubes are modified with negatively charged carboxyl functional groups.

[0016] During the preparation of sub-nano carbon nanotubes by ultrasonic cutting, the unsaturated carbon atoms at the ends of the carbon nanotubes can easily become chemical functionalization sites, automatically generating negatively charged carboxyl groups (-COOH). The acidity coefficient of the carboxyl groups is ~5. Therefore, when pH>5, the hydrogen ions of the carboxyl groups dissociate and become negatively charged.

[0017] S3: Add phospholipid molecules to the modified end-functionalized carbon nanotube solution to a concentration of 2.4-2.6 mg / mL and integrin to a concentration of 0.23-0.25 mg / mL, mix well, and let stand at room temperature for 20-30 min;

[0018] S4: Perform freeze-thaw treatment on the solution. The solution is rapidly frozen in liquid nitrogen and then thawed in a water bath at 45-52℃. Repeat this process 7-10 times.

[0019] S5: The solution is extruded and shaped through a porous polycarbonate membrane with a pore size of 180-200nm to obtain single-walled phospholipid vesicles with a diameter of 180-200nm. The phospholipid vesicle walls are loaded with sub-nano carbon nanotubes and integrase proteins.

[0020] S6: Add sodium chloroacetate to 0.10-0.12 mM and sodium hydroxide to 0.10-0.12 mM in sequence to a graphene oxide solution with a concentration of 0.8-1.2 mg / mL, and let it stand for 20-30 min to modify the surface of the graphene oxide layer with carboxyl functional groups.

[0021] S7: Carbodiimide to 1.9-2.1 mM and hydroxysuccinimide to 0.4-0.6 mM are added sequentially to the solution to convert the carboxyl functional group into an amine reaction intermediate. Anti-adhesion peptide to 0.5-0.7 mg / mL is added to modify the surface of the graphene oxide layer with anti-adhesion peptide.

[0022] S8: Mix the phospholipid vesicle solution obtained in step S5 with the graphene oxide solution obtained in step S7, and ultrasonically bathe in water for 20-30 minutes. The phospholipid vesicles rupture and recombine to form a phospholipid bilayer loaded with sub-nano carbon nanotubes and integrative proteins, which are then encapsulated in the interlayer channels of graphene oxide. Finally, obtain the graphene oxide reverse osmosis membrane with integrated sub-nano carbon nanotubes by vacuum filtration.

[0023] Further, in the sub-carbon nanotube solution obtained in step S2, carbodiimide to 1.0-1.2 mM and hydroxysuccinimide to 0.20-0.22 mM are added sequentially, and the solution is ultrasonically bathed in water for 20-30 min. Unsaturated carbon atoms at the ends of the sub-carbon nanotubes generate reaction intermediates. Then, a surface modifier to 0.10-0.12 mM is added to modify the ends of the sub-carbon nanotubes with neutral or positively charged functional groups.

[0024] Furthermore, the surface modifier is ethylenediamine, and the ends of the sub-nano carbon nanotubes are modified with positively charged ethylenediamine functional groups.

[0025] Furthermore, the surface modifier is methylamine, and the ends of the sub-nano carbon nanotubes are modified with neutral methylamine functional groups. Carbodiimide (EDC) / hydroxysuccinimide (NHS) is a commonly used chemical crosslinking agent or catalyst. Carboxylic acid (-COOH) can react with NHS in the presence of EDC to obtain a semi-stable NHS ester, which then reacts with amine (-NH2) to form an amide crosslink, thereby modifying the functional groups. Due to its different hydrogen bonding and electrostatic interactions with water molecules and ions, it can promote water flux and desalination rate.

[0026] The beneficial effects of this invention are as follows:

[0027] 1. The reverse osmosis membrane of the present invention has high structural stability. The sub-nano carbon nanotubes attract each other to the head hydrophilic groups and the inner hydrophobic groups of the phospholipid bilayer through the hydrophilic functional groups at the ends and the hydrophobic tube walls in the middle, respectively, so that the carbon nanotubes can spontaneously insert into the phospholipid bilayer. The phospholipid bilayer is bonded to the anti-adhesion polypeptide on the surface of the graphene oxide layer through integrase proteins, so as to keep the height of the interlayer channel of the graphene oxide unchanged and keep the phospholipid bilayer firmly encapsulated in the interlayer channel of the graphene oxide.

[0028] 2. The graphene oxide integrated with sub-nano carbon nanotubes of this invention has superior desalination performance. During reverse osmosis, the solution can flow sequentially through the pores of the graphene oxide layer, the interlayer channels of the graphene oxide layer, and the sub-nano carbon nanotubes. The sub-nano carbon nanotubes utilize the channel size effect and the electrostatic effect of the end functional groups to promote water flux and desalination rate. Water molecules can pass through quickly, while salt ions cannot pass through, achieving high water flux and high desalination rate seawater desalination. The desalination rate can be increased to >99.9%, and the water flux is increased by 2-3 orders of magnitude compared with commercial membranes.

[0029] 3. At the same time, during the reverse osmosis process, the graphene oxide layer plays a certain role in pretreatment of the seawater to be treated by relying on the pores of the graphene oxide layer and the channels between the graphene oxide layers, removing larger impurity particles other than salt ions in advance; at the same time, the graphene oxide layer helps to resist the impact of strong water flow caused by external pressure, protecting the phospholipid bilayer and sub-nano carbon nanotubes from being damaged. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, 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.

[0031] Figure 1 This is a schematic diagram of the overall structure of the graphene oxide reverse osmosis membrane with integrated sub-nano carbon nanotubes provided in Embodiment 1 of the present invention.

[0032] Figure 2 This is a schematic diagram of the structure anchored by the graphene oxide and phospholipid bilayer in Example 1 of the present invention;

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Sub-nano carbon nanotubes; 2. Graphene oxide layer; 3. Pores in graphene oxide layer; 4. Interlayer channels in graphene oxide; 5. Phospholipid bilayer; 6. Defects in phospholipid bilayer; 7. Integral protein; 8. Anti-adhesion peptide; 9. Terminal functional groups. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] like Figures 1 to 2 As shown, the graphene oxide reverse osmosis membrane with integrated sub-nano carbon nanotubes of the present invention includes sub-nano carbon nanotubes 1, a graphene oxide layer 2, and a phospholipid bilayer 5; the sub-nano carbon nanotubes 1 are modified with end functional groups 9; the graphene oxide layer 2 has inherent graphene oxide layer pores 3 and highly tunable graphene oxide interlayer channels 4, and the surface of the graphene oxide layer 2 is modified with anti-adhesion peptides 8; the phospholipid bilayer 5 has inherent phospholipid bilayer defects 6, and an integrase protein 7 is loaded in the phospholipid bilayer 5.

[0038] The preparation method and working process of the graphene oxide reverse osmosis membrane with integrated sub-nanometer carbon nanotubes described in this invention are as follows:

[0039] Step 1: Synthesize or directly purchase single-walled carbon nanotube raw materials with a diameter of less than 1 nm for subsequent processing and integration. According to embodiments of the present invention, the method for synthesizing single-walled carbon nanotubes is not particularly limited, and those skilled in the art can use existing methods such as chemical vapor deposition for synthesis.

[0040] Step 2: Mix 1 mg of single-walled carbon nanotube raw material with 8 mL of pure water and 28 mg of phospholipid molecules (DOPC), and use an ultrasonic cutter to cut the long carbon nanotubes in a 30°C constant temperature oven for 16 hours.

[0041] Step 3: Centrifuge for 1 hour using an ultra-high speed centrifuge (12000 rpm) to remove unbroken carbon nanotubes and impurities, and obtain a solution of sub-nano carbon nanotubes wrapped with phospholipid molecules. Characterize the diameter and length of the sub-nano carbon nanotubes using an atomic force microscope.

[0042] Step 4: Carbodiimide (EDC) to 1 mM and hydroxysuccinimide (NHS) to 0.25 mM were added sequentially to the sub-carbon nanotube solution, and the mixture was ultrasonically bathed in water for 20 min to generate amine reaction intermediates from the unsaturated carbon atoms at the ends of the sub-carbon nanotubes. Then, methylamine to 0.1 mM was added, and the neutral methylamine functional group (-NHCH3) was successfully modified at the ends of the sub-carbon nanotubes.

[0043] Among them, the functional groups at the end of the sub-nano carbon nanotubes can also be positively charged ethylenediamine functional groups (-NHCH2CH2NH2) or negatively charged carboxyl functional groups (-COOH).

[0044] Step 5: Mix the sub-nano carbon nanotube solution with modified terminal functional groups, 20 mg of phospholipid molecules, and 2 mg of integrin, and let it stand at room temperature for 30 min;

[0045] Step 6: Perform freeze-thaw treatment on the solution. The solution is rapidly frozen in liquid nitrogen and then thawed in a 50°C water bath. Repeat this process 7 times.

[0046] Step 7: The solution is shaped by being extruded 21 times through a porous polycarbonate membrane with a pore size of 200 nm to obtain single-walled phospholipid vesicles with a diameter of about 200 nm. The phospholipid vesicle walls are loaded with sub-nano carbon nanotubes and integrins. The size and density of the phospholipid vesicles are characterized using a dynamic light scattering instrument.

[0047] Step 8: Synthesize or directly purchase graphene oxide for subsequent processing and integration. According to embodiments of the present invention, the method for synthesizing graphene oxide is not particularly limited, and those skilled in the art can use existing technologies such as the Hummer method using graphene as a raw material for synthesis.

[0048] Step 9: Add sodium chloroacetate to 0.1 mM and sodium hydroxide to 0.1 mM in sequence to 100 mL of graphene oxide solution with a concentration of 1 mg / mL, and let stand for 20 min to modify the surface of the graphene oxide layer with carboxyl functional groups.

[0049] Step 10: Carbodiimide to 2 mM and hydroxysuccinimide to 0.5 mM are added sequentially to the solution to convert the carboxyl functional group into an amine reaction intermediate. Then, 5 mg of anti-adhesion peptide (GRGDS) is added to modify the surface of the graphene oxide layer with the anti-adhesion peptide.

[0050] Step 11: Mix the phospholipid vesicle solution obtained in Step 7 with the graphene oxide solution obtained in Step 10, and ultrasonically bathe in water for 20 minutes. Then, obtain an integrated sub-nano carbon nanotube graphene oxide reverse osmosis membrane by vacuum filtration. During the ultrasonic water bath process, the phospholipid vesicles rupture and recombine to form a phospholipid bilayer loaded with sub-nano carbon nanotubes and integrase proteins, which are then encapsulated in the interlayer channels of graphene oxide.

[0051] Step 12: Using confocal microscopy, the optical contrast before and after the mixing treatment of graphene oxide solution and phospholipid vesicle solution in steps 10 and 11 was compared to confirm that the phospholipid bilayer loaded with sub-nanocarbon nanotubes was successfully encapsulated in the interlayer channels of graphene oxide. Atomic force microscopy was then used to characterize the thickness and surface roughness of the graphene oxide reverse osmosis membrane integrated with sub-nanocarbon nanotubes. This method can improve the desalination rate to over 99.5%.

[0052] The present invention has the following advantages:

[0053] Traditional commercial seawater desalination reverse osmosis membranes can achieve a water flux of 2-3 mL / m³. 2 With a desalination rate of 98%-99.7% per h / bar (the desalination rate of reverse osmosis membranes needs to be >99.5% for the produced water to meet drinking standards), traditional reverse osmosis membranes have a serious trade-off between water flux and desalination rate. That is, while increasing the membrane desalination rate, the water flux will decrease. Usually, in order to achieve the target desalination rate, a significant loss of water flux must be made. Therefore, the seawater desalination performance of traditional reverse osmosis membranes is difficult to improve further.

[0054] Compared to commercial membranes, membranes made from large-sized carbon nanotubes in existing technologies can increase water flux by 2-5 orders of magnitude, but the desalination rate is only 10%-50%. Compared to commercial membranes, single sub-carbon nanotubes can increase water flux by 3-5 orders of magnitude and achieve a desalination rate of 99%-99.5%, but unintegrated single sub-carbon nanotubes cannot be used for commercial purposes.

[0055] This invention effectively integrates sub-nano carbon nanotubes and modifies them with different functional groups, similar to the effect of biological channels (referring to aquaporins). The desalination rate can be increased to >99.9%. At the same time, due to the porosity issue, the water flux is reduced to some extent, but it is increased by 2-3 orders of magnitude compared with commercial membranes.

[0056] The graphene oxide reverse osmosis membrane with integrated sub-nano carbon nanotubes prepared through the above steps has high structural stability. The sub-nano carbon nanotubes attract each other with the hydrophilic functional groups at their ends and the hydrophobic tube walls in the middle, respectively, allowing the carbon nanotubes to spontaneously insert into the phospholipid bilayer. The phospholipid bilayer binds to the anti-adhesion peptides on the surface of the graphene oxide layer through integrase proteins, maintaining the height of the interlayer channels in the graphene oxide layer and ensuring that the phospholipid bilayer is firmly encapsulated in the interlayer channels of the graphene oxide layer.

[0057] Finally, in the reverse osmosis test, the graphene oxide reverse osmosis membrane with integrated sub-nano carbon nanotubes was sealed and clamped between two liquid pools. One liquid pool was filled with a sodium chloride solution with the same concentration as seawater. Under the action of external pressure, the solution flowed through the membrane into the other liquid pool. The water flow rate and salt concentration of the filtered solution were measured to evaluate the desalination performance of the membrane.

[0058] In the reverse osmosis process, the solution flows sequentially through the pores of the graphene oxide layer, the interlayer channels of the graphene oxide layer, and the sub-nano carbon nanotubes. The sub-nano carbon nanotubes utilize the channel size effect and the electrostatic effect of the end functional groups to allow water molecules to pass through quickly, while salt ions cannot pass through, thus achieving high water flux and high desalination rate seawater desalination.

[0059] During the reverse osmosis process, the graphene oxide layer plays a certain role in pretreatment of the seawater to be treated by means of the pores of the graphene oxide layer and the channels between the graphene oxide layers, removing larger impurity particles such as salt ions in advance; at the same time, the graphene oxide layer helps to resist the impact of strong water flow caused by external pressure, protecting the phospholipid bilayer and sub-nano carbon nanotubes from being damaged.

[0060] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An integrated graphene oxide reverse osmosis membrane with sub-nanotubes, characterized in that, The application relates to a graphene oxide layer and a phospholipid bilayer loaded with sub-nanometer carbon tubes and integrins, the graphene oxide layer being surface-modified with anti-adhesion polypeptides, the integrins being bonded with the anti-adhesion polypeptides, the anchoring of the graphene oxide and the phospholipid bilayer being realized, the graphene oxide layer having graphene oxide layer pores and graphene oxide layer interlayer channels, the phospholipid bilayer being encapsulated in the graphene oxide layer interlayer channels, the sub-nanometer carbon tubes being mutually attracted to the groups of the phospholipid bilayer through end functional groups and middle hydrophobic tube walls, so that the carbon tubes can be spontaneously inserted into the phospholipid bilayer.

2. The integrated graphene oxide reverse osmosis membrane of nanotubes of claim 1, wherein, The hydrophilic functional groups for modifying the ends of the sub-nanometer carbon tubes include neutral methylamine functional groups, positively charged ethylenediamine functional groups or negatively charged carboxyl functional groups.

3. The method for preparing an integrated sub-nano carbon nanotube graphene oxide reverse osmosis membrane according to claim 1, characterized in that, The application also discloses a preparation method of the graphene oxide reverse osmosis membrane integrated with the sub-nanometer carbon tubes. The application relates to a graphene oxide layer and a phospholipid bilayer loaded with sub-nanometer carbon tubes and integrins, the graphene oxide layer being surface-modified with anti-adhesion polypeptides, the integrins being bonded with the anti-adhesion polypeptides, the anchoring of the graphene oxide and the phospholipid bilayer being realized, the graphene oxide layer having graphene oxide layer pores and graphene oxide layer interlayer channels, the phospholipid bilayer being encapsulated in the graphene oxide layer interlayer channels, the sub-nanometer carbon tubes being mutually attracted to the groups of the phospholipid bilayer through end functional groups and middle hydrophobic tube walls, so that the carbon tubes can be spontaneously inserted into the phospholipid bilayer. The hydrophilic functional groups for modifying the ends of the sub-nanometer carbon tubes include neutral methylamine functional groups, positively charged ethylenediamine functional groups or negatively charged carboxyl functional groups. The application also discloses a preparation method of the graphene oxide reverse osmosis membrane integrated with the sub-nanometer carbon tubes. The application relates to a graphene oxide layer and a phospholipid bilayer loaded with sub-nanometer carbon tubes and integrins, the graphene oxide layer being surface-modified with anti-adhesion polypeptides, the integrins being bonded with the anti-adhesion polypeptides, the anchoring of the graphene oxide and the phospholipid bilayer being realized, the graphene oxide layer having graphene oxide layer pores and graphene oxide layer interlayer channels, the phospholipid bilayer being encapsulated in the graphene oxide layer interlayer channels, the sub-nanometer carbon tubes being mutually attracted to the groups of the phospholipid bilayer through end functional groups and middle hydrophobic tube walls, so that the carbon tubes can be spontaneously inserted into the phospholipid bilayer. The hydrophilic functional groups for modifying the ends of the sub-nanometer carbon tubes include neutral methylamine functional groups, positively charged ethylenediamine functional groups or negatively charged carboxyl functional groups. The application also discloses a preparation method of the graphene oxide reverse osmosis membrane integrated with the sub-nanometer carbon tubes. The application relates to a graphene oxide layer and a phospholipid bilayer loaded with sub-nanometer carbon tubes and integrins, the graphene oxide layer being surface-modified with anti-adhesion polypeptides, the integrins being bonded with the anti-adhesion polypeptides, the anchoring of the graphene oxide and the phospholipid bilayer being realized, the graphene oxide layer having graphene oxide layer pores and graphene oxide layer interlayer channels, the phospholipid bilayer being encapsulated in the graphene oxide layer interlayer channels, the sub-nanometer carbon tubes being mutually attracted to the groups of the phospholipid bilayer through end functional groups and middle hydrophobic tube walls, so that the carbon tubes can be spontaneously inserted into the phospholipid bilayer. The hydrophilic functional groups for modifying the ends of the sub-nanometer carbon tubes include neutral methylamine functional groups, positively charged ethylenediamine functional groups or negatively charged carboxyl functional groups. The application also discloses a preparation method of the graphene oxide reverse osmosis membrane integrated with the sub-nanometer carbon tubes.

4. The method of claim 3, wherein the integrated graphene oxide reverse osmosis membrane is prepared by the steps of: providing a graphene oxide membrane; and depositing carbon nanotubes on the graphene oxide membrane. The sub-nanometer carbon tube solution obtained in the step S2 is added with carbodiimide to 1.0-1.2 mM, hydroxyl succinimide to 0.20-0.22 mM, and ultrasonic water bath for 20-30 min, so that the end unsaturated carbon atoms of the sub-nanometer carbon tube generate a reaction intermediate, and then a surface modifier is added to 0.10-0.12 mM to modify neutral functional groups or positively charged functional groups at the end of the sub-nanometer carbon tube.

5. The method of claim 4, wherein the integrated graphene oxide reverse osmosis membrane is prepared by the steps of: providing a graphene oxide membrane; providing a carbon nanotube; and integrating the carbon nanotube with the graphene oxide membrane. The surface modifier is ethylenediamine, and the end of the sub-nanometer carbon tube is modified with positively charged ethylenediamine functional groups.

6. The method of claim 4, wherein the integrated graphene oxide reverse osmosis membrane is prepared by the steps of: providing a graphene oxide membrane; providing a carbon nanotube; and integrating the carbon nanotube with the graphene oxide membrane. The surface modifier is methylamine, and the end of the sub-nanometer carbon tube is modified with neutral methylamine functional groups.

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