Preparation method and application of GO / silicone composite nanofiltration membrane

Abstract

The application discloses a preparation method of a GO / organic silicon composite nanofiltration membrane and application thereof, and belongs to the technical field of nanofiltration membranes. The application discloses a preparation method of a GO / organic silicon composite nanofiltration membrane and application thereof, and belongs to the technical field of nanofiltration membranes. The GO / organic silicon composite nanofiltration membrane prepared by the application has good water permeability (≥7.2 L / (m 2 h bar) and dye retention rate (≥99.1%) in dye separation application.

Description

Technical Field

[0001] This invention belongs to the field of composite membrane preparation, specifically relating to a method for preparing a GO / organosilicon composite nanofiltration membrane and its application. Background Technology

[0002] Graphene is a type of carbon atom arranged in sp... 2 Two-dimensional carbon nanomaterials, with hexagonal honeycomb lattices composed of hybrid orbitals, possess unique single-atom thicknesses and exhibit excellent mechanical properties, thermal stability, and electrical properties. Two-dimensional materials, due to their tunable sub-nanometer transport channels, are ideal materials for membrane separation. Graphene oxide (GO), as a typical two-dimensional material, can be used to prepare high-throughput multilayer membranes through simple, ordered stacking. However, GO membranes exhibit poor stability and mechanical properties during liquid separation, making the improvement of GO membrane structural stability a pressing issue. For example, Chinese patent CN112774463A discloses a structurally stable graphene oxide separation membrane and its preparation method, utilizing the hydrophilicity and unique layered structure of graphene oxide to achieve layer-by-layer self-assembly with cage-like silsesquioxane particles to improve the stability of the GO membrane.

[0003] Ultrasonic atomization thermal spraying is a new technology that has developed in recent years and has made considerable progress in the preparation of conductive thin films, as reported in numerous domestic and international publications. Unlike traditional processes such as casting, this technology is simple to operate, requires no vacuum conditions, can deposit thin films over large areas, and can deposit on three-dimensional surfaces. It has a high deposition rate, is easy to implement in industrial production, and can produce high-quality thin films with uniform surfaces and more precise control over film thickness.

[0004] Currently, there are no reports of using graphene oxide to produce high-quality thin films via ultrasonic atomization thermal spraying technology. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a GO / organosilicon composite nanofiltration membrane.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a GO / organosilicon composite nanofiltration membrane, comprising,

[0009] Graphene oxide (GO) was added to tetrahydrofuran solvent for solvent displacement to prepare a tetrahydrofuran solution.

[0010] Graphene oxide (GO) nanosheets and organosilicon precursors were added to a tetrahydrofuran solution, hydrochloric acid was added as a catalyst, the mixed solvent was stirred, and after the reaction was completed, the mixed solution was centrifuged and replaced with ethanol solvent to obtain a pre-crosslinked sol.

[0011] Bridged organosilicon sol was prepared by hydrolysis-condensation reaction of pre-crosslinked sol, organosilicon precursor, water and hydrochloric acid.

[0012] The bridging organosilicon sol was uniformly sprayed onto a preheated ceramic support by ultrasonic thermal spraying, and then heat-treated to obtain a GO / organosilicon composite nanofiltration membrane.

[0013] In a preferred embodiment of the preparation method described in this invention, the GO nanosheets have a monolayer ratio greater than 99.5% and a radial dimension of 5–8 μm, and the tetrahydrofuran solution has a concentration of 0.5–0.8 mg / ml.

[0014] As a preferred embodiment of the preparation method described in this invention, the silicon source precursor includes 3-aminopropyltriethoxysilane APTSE, wherein the ratio of the pre-crosslinked sol to the organosilicon precursor is 1g:1-2g.

[0015] In a preferred embodiment of the preparation method described in this invention, the pre-crosslinked sol contains GO nanosheets, organosilicon precursor, tetrahydrofuran solution and catalyst in a ratio of 1g:1-2g:15-18g:0.2g.

[0016] As a preferred embodiment of the preparation method of the present invention, the catalyst is 37wt% hydrochloric acid, the reaction temperature for preparing the pre-crosslinked sol is 70-80℃, and the reaction time is 7-8h; the centrifugal displacement is carried out at a centrifugal speed of 8000-12000r / min, a centrifugation time of 20-30min, and a displacement number of 3-5 times.

[0017] In a preferred embodiment of the preparation method described in this invention, the hydrolysis-condensation reaction is wherein the molar ratio of organosilicon precursor, water, and hydrochloric acid is 1:60-90:0.1-0.2, the reaction temperature is 40-60°C, and the reaction time is 2-4 hours.

[0018] In a preferred embodiment of the preparation method described in this invention, the bridged organosilicon sol is applied by ultrasonic thermal spraying, wherein the concentration of the feed solution of the ultrasonic equipment is 0.5–2 wt%, the ultrasonic power is 0.5–3 Hz, the feed flow rate is 0.1–2 ml / min, the air carrier pressure is 0.01–0.05 MPa, the single-pass spraying step distance is 1–5 mm, and the distance between the nozzle and the support is 2–4 cm.

[0019] The surface temperature of the preheated GO film is 30-50℃, the effective spraying area is 10×10cm, the single spraying time is 1-2min, and a total of 2 sprays are applied.

[0020] As a preferred embodiment of the preparation method described in this invention, the ceramic support is a γ-Al2O3 ceramic support with a pore size of 100-200 nm; the post-treatment involves treating the graphene oxide / bridged organosilicon hybrid nanofiltration membrane at 80-120°C for 15-30 min.

[0021] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a GO / organosilicon composite nanofiltration membrane.

[0022] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of a GO / organosilicon composite nanofiltration membrane in dye / water separation, wherein the dye includes Rhodamine B.

[0023] Beneficial effects of this invention:

[0024] (1) The GO / organosilicon membrane prepared in this invention is applied to a dye / water separation system (100ppm Rhodamine B). First, GO and organosilicon precursor are "pre-crosslinked" to form a sol, and then crosslinked sol is prepared by acid catalysis to improve the stability of the prepared organosilicon hybrid membrane. The hydrophilicity of graphene oxide and the sieving performance of the bridging organosilicon network structure are combined to improve the separation performance of the hybrid membrane.

[0025] (2) In this invention, a GO / organosilicon hybrid nanofiltration membrane was prepared on an alumina support by ultrasonic atomization spraying. The sol was uniformly dispersed on the support, and the solvent evaporated rapidly to form a membrane layer with uniform thickness and smooth surface. After post-treatment, a stable separation layer was formed. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments 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. Wherein:

[0027] Figure 1 This is a schematic diagram of the process for preparing the GO / organosilicon nanofiltration membrane in Example 1 of the present invention.

[0028] Figure 2 The images show SEM images of the surface and cross-section of the GO / HTOS nanofiltration membrane in Embodiment 1 of the present invention.

[0029] Figure 3 This is a thermal stability test diagram of the GO / HTOS nanofiltration membrane in Embodiment 1 of the present invention. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0033] Example 1

[0034] (1) 1g of graphene oxide (manufacturer: Hangzhou High Rare Earth Technology Co., Ltd., monolayer ratio: >99.5%, radial size: 5-8μm) was added to tetrahydrofuran solvent to form a 0.5mg / ml GO dispersion;

[0035] (2) 1g of GO nanosheets (manufacturer: Hangzhou Gaoxi Technology Co., Ltd., monolayer ratio: >99.5%, radial size: 5-8μm) and 1g of 3-aminopropyltriethoxysilane (APTES) were added to 17g of tetrahydrofuran solvent. 0.2g of concentrated hydrochloric acid with a concentration of 37wt% was added as a catalyst. The mixture was stirred at 70℃ for 7h to obtain a "pre-crosslinked" sol. The mixed solution was centrifuged with ethanol solvent at a speed of 8000r / min for three times.

[0036] (3) Add 1g of the “pre-crosslinked” sol prepared in step (2) and 1g of 3-aminopropyltriethoxysilane (APTES) to ethanol, stir for 1-2 min, then add deionized water dropwise, continue stirring for 1-2 min, and then add concentrated hydrochloric acid dropwise. The molar ratio of silicon source precursor, water and hydrochloric acid is 1:60:0.2 to carry out hydrolysis-condensation reaction. The reaction temperature is 40℃ and the reaction time is 2h to obtain 5wt% mixed sol.

[0037] (4) Dilute the organosilicon sol prepared in step (3) to 1 wt%, inject it into a syringe and fix it, the ultrasonic controller recognizes the signal, the liquid injection speed is 0.1 ml / min, the ultrasonic frequency is 1.5 Hz, the nozzle height is 20 mm, the single spraying step distance is 1 mm, the sol is dispersed into tiny uniform droplets by ultrasonic action, and enters the deposition chamber with nitrogen gas, the gas carrier pressure is 0.02 MPa;

[0038] Tiny droplets are uniformly deposited onto the GO film from the spray nozzle at a substrate temperature of 40°C. One deposition is completed in 2 minutes, followed by 2 minutes of natural solvent evaporation. The coating is then applied twice and treated at 80°C for 20 minutes.

[0039] The prepared membrane was applied to a dye / water separation system (100 ppm Rhodamine B) under constant operating pressure, feed concentration, and operating temperature of 70 °C.

[0040] See the schematic diagram of the GO / organosilicon nanofiltration membrane preparation process. Figure 1 .

[0041] SEM images of the surface and cross-section of the GO / HTOS nanofiltration membrane are shown below. Figure 2 As can be seen from the cross-section of the GO / HTOS nanofiltration membrane, the membrane surface is continuous with almost no defects. The particles on the membrane are sputtering particles left over from the preparation of the sample. The top layer of the cross-sectional structure is the GO / HTOS nanofiltration membrane separation layer, which is about 150 nm thick.

[0042] See the thermal stability test diagram of the GO / HTOS nanofiltration membrane. Figure 3 As shown in the figure, under the premise that the operating pressure, raw material concentration and operating temperature are kept constant at 70℃, the system can maintain good hydrothermal stability and high dye rejection rate when operating under heated conditions. However, the water permeability will increase as the operating time increases.

[0043] Example 2

[0044] (1) 1g of graphene oxide (manufacturer: Hangzhou High Rare Earth Technology Co., Ltd., monolayer ratio: >99.5%, radial size: 5-8μm) was added to tetrahydrofuran solvent to form a 0.5mg / ml GO dispersion;

[0045] (2) 1g of GO nanosheets (manufacturer: Hangzhou Gaoxi Technology Co., Ltd., monolayer ratio: >99.5%, radial size: 5-8μm) and 1g of 3-aminopropyltriethoxysilane (APTES) were added to 17g of tetrahydrofuran solvent. 0.2g of concentrated hydrochloric acid with a concentration of 37wt% was added as a catalyst. The mixture was stirred at 70℃ for 7h to obtain a "pre-crosslinked" sol. The mixed solution was centrifuged with ethanol solvent at a speed of 8000r / min for three times.

[0046] (3) Add 1g of the “pre-crosslinked” sol prepared in step (2) and 1g of 3-aminopropyltriethoxysilane (APTES) to ethanol, stir for 1-2 min, then add deionized water dropwise, continue stirring for 1-2 min, and then add concentrated hydrochloric acid dropwise. The molar ratio of silicon source precursor, water and hydrochloric acid is 1:90:0.2 to carry out hydrolysis-condensation reaction. The reaction temperature is 40℃ and the reaction time is 2h to obtain 5wt% mixed sol.

[0047] (4) Dilute the organosilicon sol prepared in step (3) to 1 wt%, inject it into a syringe and fix it, the ultrasonic controller recognizes the signal, the liquid injection speed is 0.1 ml / min, the ultrasonic frequency is 1.5 Hz, the nozzle height is 20 mm, the single spraying step distance is 1 mm, the sol is dispersed into tiny uniform droplets by ultrasonic action, and enters the deposition chamber with nitrogen gas, the gas carrier pressure is 0.03 MPa.

[0048] Tiny droplets are uniformly deposited onto the GO film from the spray nozzle at a substrate temperature of 40°C. One deposition is completed in 2 minutes, followed by 2 minutes of natural solvent evaporation. The coating is then applied twice and treated at 80°C for 20 minutes.

[0049] The prepared membrane was applied to a dye / water separation system (100 ppm Rhodamine B) under constant operating pressure, feed concentration, and operating temperature of 70 °C.

[0050] Example 3

[0051] (1) 1g of graphene oxide (manufacturer: Hangzhou High Rare Earth Technology Co., Ltd., monolayer ratio: >99.5%, radial size: 5-8μm) was added to tetrahydrofuran solvent to form a 0.5mg / ml GO dispersion;

[0052] (2) 1g of GO nanosheets (manufacturer: Hangzhou Gaoxi Technology Co., Ltd., monolayer ratio: >99.5%, radial size: 5-8μm) and 1g of 3-aminopropyltriethoxysilane (APTES) were added to 17g of tetrahydrofuran solvent. 0.2g of concentrated hydrochloric acid with a concentration of 37wt% was added as a catalyst. The mixture was stirred at 80℃ for 8h to obtain a "pre-crosslinked" sol. The mixed solution was centrifuged with ethanol solvent at a speed of 10000r / min for three times.

[0053] (3) Add 1g of the “pre-crosslinked” sol prepared in step (2) and 1g of 3-aminopropyltriethoxysilane (APTES) to ethanol, stir for 1-2 min, then add deionized water dropwise, continue stirring for 1-2 min, and then add concentrated hydrochloric acid dropwise. The molar ratio of silicon source precursor, water and hydrochloric acid is 1:60:0.2 to carry out hydrolysis-condensation reaction. The reaction temperature is 40℃ and the reaction time is 4h to obtain 5wt% mixed sol.

[0054] (4) Dilute the organosilicon sol prepared in step (3) to 1 wt%, inject it into a syringe and fix it, the ultrasonic controller recognizes the signal, the liquid injection speed is 1.0 ml / min, the ultrasonic frequency is 1.5 Hz, the nozzle height is 20 mm, the single spraying step distance is 3 mm, the sol is dispersed into tiny uniform droplets by ultrasonic action, and enters the deposition chamber with nitrogen gas, the gas carrier pressure is 0.03 MPa.

[0055] Tiny droplets are uniformly deposited onto the GO film from the spray nozzle at a substrate temperature of 40°C. One deposition is completed in 2 minutes, followed by 2 minutes of natural solvent evaporation. The coating is then applied twice and treated at 80°C for 20 minutes.

[0056] The prepared membrane was applied to a dye / water separation system (100 ppm Rhodamine B) under constant operating pressure, feed concentration, and operating temperature of 70 °C.

[0057] Example 4

[0058] (1) 1g of graphene oxide (manufacturer: Hangzhou High Rare Earth Technology Co., Ltd., monolayer ratio: >99.5%, radial size: 5-8μm) was added to tetrahydrofuran solvent to form a 0.5mg / ml GO dispersion;

[0059] (2) 1g of GO nanosheets (manufacturer: Hangzhou Gaoxi Technology Co., Ltd., monolayer ratio: >99.5%, radial size: 5-8μm) and 1g of 3-aminopropyltriethoxysilane (APTES) were added to 17g of tetrahydrofuran solvent. 0.2g of concentrated hydrochloric acid with a concentration of 37wt% was added as a catalyst. The mixture was stirred at 70℃ for 8h to obtain a "pre-crosslinked" sol. The mixed solution was centrifuged with ethanol solvent at a speed of 12000r / min for three times.

[0060] (3) Add 1g of the “pre-crosslinked” sol prepared in step (2) and 1g of 3-aminopropyltriethoxysilane (APTES) to ethanol, stir for 1-2 min, then add deionized water dropwise, continue stirring for 1-2 min, and then add concentrated hydrochloric acid dropwise. The molar ratio of silicon source precursor, water and hydrochloric acid is 1:60:0.2 to carry out hydrolysis-condensation reaction. The reaction temperature is 40℃ and the reaction time is 2h to obtain 5wt% mixed sol.

[0061] (4) Dilute the organosilicon sol prepared in step (3) to 2wt%, inject it into the syringe and fix it, the ultrasonic controller recognizes the signal, the liquid injection speed is 1.0ml / min, the ultrasonic frequency is 2.0Hz, the nozzle height is 40mm, the single spraying step distance is 4mm, the sol is dispersed into tiny uniform droplets by ultrasonic action, and enters the deposition chamber with nitrogen gas, the gas carrier pressure is 0.04MPa.

[0062] Tiny droplets are uniformly deposited onto the GO film from the spray nozzle at a substrate temperature of 40°C. One deposition is completed in 1 minute, followed by 2 minutes of natural solvent evaporation. The film is then sprayed twice and treated at 120°C for 30 minutes.

[0063] The prepared membrane was applied to a dye / water separation system (100 ppm Rhodamine B) under constant operating pressure, feed concentration, and operating temperature of 70 °C.

[0064] Example 5

[0065] (1) 1g of graphene oxide (manufacturer: Hangzhou High Rare Earth Technology Co., Ltd., monolayer ratio: >99.5%, radial size: 5-8μm) was added to tetrahydrofuran solvent to form a 0.5mg / ml GO dispersion;

[0066] (2) 1g of GO nanosheets (manufacturer: Hangzhou Gaoxi Technology Co., Ltd., monolayer ratio: >99.5%, radial size: 5-8μm) and 1g of 3-aminopropyltriethoxysilane (APTES) were added to 17g of tetrahydrofuran solvent. 0.2g of concentrated hydrochloric acid with a concentration of 37wt% was added as a catalyst. The mixture was stirred at 70℃ for 7h to obtain a "pre-crosslinked" sol. The mixed solution was centrifuged with ethanol solvent at a speed of 8000r / min for three times.

[0067] (3) Add 1g of the “pre-crosslinked” sol prepared in step (2) and 1g of 3-aminopropyltriethoxysilane (APTES) to ethanol, stir for 1-2 min, then add deionized water dropwise, continue stirring for 1-2 min, and then add concentrated hydrochloric acid dropwise. The molar ratio of silicon source precursor, water and hydrochloric acid is 1:90:0.2 to carry out hydrolysis-condensation reaction. The reaction temperature is 60℃ and the reaction time is 4h to obtain 5wt% mixed sol.

[0068] (4) The organosilicon sol prepared in step (3) was diluted to 2 wt%, injected into a syringe and fixed. The ultrasonic controller recognized the signal, the liquid injection rate was 0.1 ml / min, the ultrasonic frequency was 3.0 Hz, the nozzle height was 30 mm, and the single-pass spraying step distance was 5 mm. The sol was dispersed into tiny uniform droplets by ultrasonic action and entered the deposition chamber with nitrogen gas at a gas carrier pressure of 0.05 MPa. The tiny droplets were uniformly deposited on the GO membrane from the spray nozzle at a substrate temperature of 40 °C. One deposition was completed in 2 min, and the solvent was allowed to evaporate naturally for 2 min. The coating was repeated twice, and the membrane was treated at 80 °C for 20 min. The prepared membrane was applied to a dye / water separation system (100 ppm Rhodamine B) under constant operating pressure, feed concentration, and operating temperature of 70 °C.

[0069] Comparative Example 1

[0070] The specific operations of steps (1) and (2) are the same as those in Example 1;

[0071] (3) 1g of the "pre-crosslinked" sol prepared in step (2) was injected into the syringe and fixed. The ultrasonic controller recognized the signal. The liquid injection rate was 0.1ml / min, the ultrasonic frequency was 1.5Hz, the nozzle height was 20mm, and the single-pass spraying step distance was 1mm. The sol was dispersed into tiny uniform droplets by ultrasonic action and entered the deposition chamber with nitrogen gas. The gas carrier pressure was 0.02MPa. The tiny droplets were uniformly deposited on the GO film from the spray nozzle. The substrate temperature was 40℃. One deposition was completed in 2min. The solvent was allowed to evaporate naturally for 2min. The coating was repeated twice and treated at 80℃ for 20min.

[0072] The prepared membrane was applied to a dye / water separation system (100 ppm Rhodamine B) under constant operating pressure, feed concentration, and operating temperature of 70 °C.

[0073] Comparative Example 2

[0074] (1) Add 3-aminopropyltriethoxysilane (APTES) to ethanol, stir for 1-2 min, then add deionized water dropwise, continue stirring for 1-2 min, and then add concentrated hydrochloric acid dropwise. The molar ratio of silicon source precursor, water and hydrochloric acid is 1:60:0.2 to carry out hydrolysis-condensation reaction. The reaction temperature is 40℃ and the reaction time is 2 h to obtain 5wt% mixed sol.

[0075] (2) Dilute 1g of the organosilicon sol prepared in step (1) to 2wt%, inject it into a syringe and fix it. The ultrasonic controller recognizes the signal, the liquid injection rate is 0.1ml / min, the ultrasonic frequency is 1.5Hz, the nozzle height is 20mm, and the single-pass spraying step distance is 1mm. The sol is dispersed into tiny uniform droplets by ultrasonic action and enters the deposition chamber with nitrogen gas. The gas carrier pressure is 0.02MPa. Tiny droplets are uniformly deposited on the GO film from the spray nozzle. The substrate temperature is 40℃. One deposition is completed in 2min. Allow the solvent to evaporate naturally for 2min. Spray twice and treat at 80℃ for 20min.

[0076] The prepared membrane was applied to a dye / water separation system (100 ppm Rhodamine B) under constant operating pressure, feed concentration, and operating temperature of 70 °C.

[0077] The experimental results of the above embodiments and comparative examples are shown in Table 1.

[0078] Table 1

[0079] Example 1 8.9 99.5 Example 2 10.3 99.2 Example 3 9.4 99.4 Example 4 12.7 99.1 Example 5 7.2 99.7 Compare with Example 1 21.1 41.5 Compare with Example 2 5.1 98.4

[0080] By selecting GO nanosheets and organosilicon materials for "pre-crosslinking," the stability of GO nanosheets is improved, forming a two-dimensional rapid mass transfer channel for water molecules. Then, the organosilicon network structure is crosslinked through hydrolysis-condensation reaction, constructing a three-dimensional stable mass transfer channel on the basis of pre-crosslinking. The hydrophilic groups on the surface of graphene oxide are used to improve the water permeability of the hybrid membrane. The hydrophilicity of GO nanosheets and the selectivity of the bridging organosilicon network work together to improve the separation performance of the hybrid membrane.

[0081] GO / organosilicon hybrid membranes were prepared on alumina ceramic films using ultrasonic atomization spraying. The bridged organosilicon sol surface contains numerous hydroxyl functional groups, which easily aggregate in water, forming an amorphous network structure that affects the performance of the bridged organosilicon membrane. The crosslinked sol is ultrasonically atomized into uniform droplets, which are then uniformly sprayed onto a preheated ceramic support. The sol rapidly spreads on the ceramic support, the solvent evaporates, and a hybrid membrane of uniform thickness and smooth surface is formed.

[0082] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing a GO / organosilicon composite nanofiltration membrane, characterized in that: include, Graphene oxide (GO) was added to tetrahydrofuran solvent for solvent displacement to prepare a tetrahydrofuran solution. Graphene oxide (GO) nanosheets and an organosilicon precursor were added to a tetrahydrofuran solvent, and hydrochloric acid was added as a catalyst. The mixture was stirred, and after the reaction was completed, the mixture was centrifuged with ethanol to obtain a pre-crosslinked sol. The organosilicon precursor was 3-aminopropyltriethoxysilane (APTES); the catalyst was 37 wt% hydrochloric acid; the reaction temperature for preparing the pre-crosslinked sol was 70-80℃, and the reaction time was 7-8 h; the centrifugation was performed at a speed of 8000-12000 r / min for 20-30 min, and the number of replacements was 3-5 times. A bridged organosilicon sol was prepared by hydrolysis-condensation reaction of pre-crosslinked sol, organosilicon precursor, water and hydrochloric acid. The ratio of pre-crosslinked sol to organosilicon precursor was 1g:1~2g, the molar ratio of organosilicon precursor, water and hydrochloric acid was 1:60~90:0.1~0.2, the reaction temperature was 40~60℃, and the reaction time was 2~4 h. The bridging organosilicon sol was uniformly sprayed onto a preheated ceramic support by ultrasonic thermal spraying, and the GO / organosilicon composite nanofiltration membrane was obtained by heat treatment at 80~120℃ for 15~30 min.

2. The preparation method according to claim 1, characterized in that: The GO nanosheets have a monolayer ratio greater than 99.5% and a radial dimension of 5-8 μm, and the tetrahydrofuran solution has a concentration of 0.5-0.8 mg / ml.

3. The preparation method according to claim 1 or 2, characterized in that: The pre-crosslinked sol contains GO nanosheets, organosilicon precursor, tetrahydrofuran solution and catalyst in a ratio of 1g:1~2g:15~18g:0.2g.

4. The preparation method according to claim 1, characterized in that: The process involves ultrasonic thermal spraying of the bridged silicone sol, wherein the concentration of the feed solution for ultrasonic thermal spraying is 0.5~2wt%, the ultrasonic power is 0.5~3 Hz, the feed flow rate is 0.1~2 ml / min, the air pressure is 0.01~0.05 MPa, the single-pass spraying step distance is 1~5 mm, and the distance between the nozzle and the support is 2~4 cm. The surface temperature of the preheated ceramic support is 30~50℃, the effective spraying area is 10×10cm, the single spraying time is 1~2min, and a total of 2 sprays are applied.

5. The preparation method according to claim 1, characterized in that: The ceramic support is a γ-Al2O3 ceramic support with a pore size of 100~200 nm.

6. The GO / organosilicon composite nanofiltration membrane prepared by any of the preparation methods described in claims 1 to 5.

7. The application of the GO / organosilicon composite nanofiltration membrane as described in claim 6 in dye / water separation, characterized in that: The dyes include Rhodamine B.

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