Fluorine-modified graphene oxide-based composite aerogel bilayer, and preparation method and application thereof

Abstract

The application discloses a fluorine-modified graphene oxide-based aerogel bilayer as well as a preparation method and application thereof, and comprises a graphene oxide-based composite aerogel, wherein a main body of the graphene oxide-based composite aerogel comprises graphene oxide and sodium cellulose or chitosan; one side of the graphene oxide-based composite aerogel is subjected to modification treatment of fluorochlorosilane to provide hydrophobic and oleophobic properties. The preparation method comprises the following steps: preparing a graphene oxide aqueous solution and an aqueous solution of sodium cellulose or chitosan; mixing the graphene oxide solution and the sodium cellulose solution or the chitosan solution; freeze-drying the mixed solution, and then vacuum drying to obtain an aerogel; and using an organic solution containing fluorochlorosilane to infiltrate a non-woven fabric, placing the infiltrated non-woven fabric on a surface of the aerogel, standing, and drying. The graphene oxide-based aerogel is subjected to hydrophobic and oleophobic modification on the upper layer by using fluorochlorosilane, and the lower layer is hydrophilic, so that the graphene oxide-based aerogel has good salt resistance and stain resistance and high evaporation efficiency, and has a wide application prospect in the field of seawater desalination.

Description

Technical Field

[0001] This invention relates to an aerogel for solar interfacial evaporation, its preparation method and application, and particularly to a fluorine-modified graphene oxide-based composite aerogel dihedron, its preparation method and application. Background Technology

[0002] With rapid societal development and a dramatic increase in population, freshwater scarcity has become one of the most severe challenges facing the world. To address this problem, researchers have turned their attention to seawater, the most abundant water resource on Earth, which accounts for approximately 97.5% of total water resources. Therefore, seawater desalination technology is considered one of the most effective methods for solving water scarcity. However, traditional seawater desalination technologies consume large amounts of fossil fuels and are costly, potentially leading to environmental problems such as the greenhouse effect and air pollution. Therefore, finding a green freshwater production technology is urgently needed. Solar-powered seawater desalination technology is of great significance in addressing freshwater scarcity and responding to the energy crisis. In recent years, interfacial solar-powered seawater desalination technology has demonstrated advantages such as environmental friendliness and low cost. By thermally localizing the heating of only a small amount of water at the evaporation interface, it achieves high evaporation efficiency.

[0003] However, for most reported interfacial solar absorbers, localized heating and rapid interfacial vapor generation can lead to salt accumulation on the evaporator surface, blocking vapor escape channels and reducing the vapor generation rate. Furthermore, oil or organic pollutants are common in seawater; when absorbers are used to purify oily seawater, oil droplets easily accumulate on the material's surface, hindering the evaporation of the aqueous phase. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a fluorine-modified graphene oxide-based composite aerogel dihedral with good salt and dirt resistance and high evaporation efficiency;

[0005] The second objective of this invention is to provide a method for preparing the above-mentioned fluorine-modified graphene oxide-based composite aerogel dihedron.

[0006] A third objective of this invention is to provide the application of the above-mentioned fluorine-modified graphene oxide-based composite aerogel dihedron in the field of seawater desalination.

[0007] Technical solution: The fluorine-modified graphene oxide-based composite aerogel of the present invention comprises a graphene oxide-based composite aerogel, wherein the graphene oxide-based composite aerogel body is prepared by combining graphene oxide with sodium cellulose or chitosan; one side of the graphene oxide-based composite aerogel is modified with fluorochlorosilane; one side of the modified graphene oxide-based composite aerogel has hydrophobic and oleophobic properties.

[0008] The preparation method of the above-mentioned fluorine-modified graphene oxide-based composite aerogel dihedron includes the following steps:

[0009] (1) Prepare aqueous solutions of graphene oxide and sodium cellulose or chitosan;

[0010] (2) Mix the aqueous solution of graphene oxide and the aqueous solution of sodium cellulose, or mix the aqueous solution of graphene oxide and the aqueous solution of chitosan; to obtain a mixture;

[0011] (3) The mixture was freeze-dried and then vacuum-dried to obtain an aerogel;

[0012] (4) The nonwoven fabric is impregnated with an organic solution containing fluorochlorosilane, the impregnated nonwoven fabric is placed on the surface of the aerogel, left to stand, and dried to obtain the product.

[0013] In step (1), the concentrations of the graphene oxide aqueous solution, the sodium cellulose aqueous solution, and the chitosan aqueous solution are all 1-10 mg / mL.

[0014] In step (2), the mass ratio of solutes in the graphene oxide aqueous solution and the sodium cellulose aqueous solution is 1:10 to 10:1; the mass ratio of solutes in the graphene oxide aqueous solution and the chitosan aqueous solution is 1:10 to 10:1.

[0015] In step (3), the freeze-drying time is 24-48h; the vacuum drying temperature is 60-150℃ and the time is 2-12h.

[0016] In step (4), the fluorochlorosilane is 1H,1H,2H,2H-perfluorodecyltrichlorosilane; the concentration of the organic solution containing the fluorochlorosilane is 1-10 vol%; the standing time is 2-8 h; the drying temperature is 60-120℃ and the time is 1-6 h.

[0017] This invention provides the application of the above-mentioned fluorine-modified graphene oxide-based composite aerogel dihedron in the field of seawater desalination.

[0018] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects: (1) The upper layer of the graphene oxide-based composite aerogel is modified to be hydrophobic and oleophobic by fluorinated chlorosilane, while the lower layer is hydrophilic. This can effectively trap salt ions and pollutants in the water to reach the surface of the absorber, giving it good salt resistance and pollution resistance, and high evaporation efficiency. (2) Graphene oxide, sodium cellulose, and chitosan contain a large number of oxygen-containing functional groups, giving the aerogel good hydrophilicity. (3) The fluorinated graphene oxide-based composite aerogel dihedron can operate stably and continuously in saturated brine for 4-8 hours. (4) The fluorinated graphene oxide-based composite aerogel dihedron has good oil-water separation performance. (5) The fluorinated graphene oxide-based composite aerogel dihedron has broad application prospects in the field of seawater desalination. Attached Figure Description

[0019] Figure 1 Optical photograph of a dihedral of a fluorine-modified graphene oxide-based composite aerogel;

[0020] Figure 2 (a) Water contact angle and (b) Oil contact angle of the unmodified side of the dihedron of fluorine-modified graphene oxide-based composite aerogel; (c) Water contact angle and (d) Oil contact angle of the modified side of the aerogel.

[0021] Figure 3 Evaporation curves of a dihedral fluorine-modified graphene oxide-based composite aerogel;

[0022] Figure 4 Optical photographs showing the changes in salt crystallization over time on the surface of fluorine-modified graphene oxide-based composite aerogels using NaCl solutions with concentrations of 3.5 (a), 5 (b), 8 (c), and 10 wt% (d) as raw water.

[0023] Figure 5 Photos showing the water before and after purification, using an oil-in-water emulsion as the raw water. Detailed Implementation

[0024] The present invention will now be described in further detail.

[0025] Example 1

[0026] A method for preparing a fluorine-modified graphene oxide-based composite aerogel dihedron includes the following steps:

[0027] Step 1: Prepare an aqueous solution of graphene oxide with a concentration of 6 mg / mL and an aqueous solution of sodium cellulose with a concentration of 10 mg / mL;

[0028] Step 2: Mix the aqueous solution of graphene oxide and the aqueous solution of sodium cellulose at a solute mass ratio of 3:1 for 5 min, sonicate for 10 min to obtain a dispersion; then transfer it to a mold and freeze it in a refrigerator.

[0029] Step 3: Freeze-dry the frozen dispersion for 48 hours, and then vacuum-dry it at 130°C for 2 hours to obtain an aerogel;

[0030] Step 4: Soak a clean nonwoven fabric in a hexane solution of 1H,1H,2H,2H-perfluorodecyltrichlorosilane at a concentration of 1 vol%. Place the soaked nonwoven fabric on the surface of the aerogel and leave it at ambient temperature for 2 hours. Then dry it at 60°C for 1 hour to obtain a fluorine-modified graphene oxide-based composite aerogel dihedron.

[0031] Performance testing:

[0032] (1) Prepare NaCl solutions with concentrations of 3.5, 5, 8 and 10 wt%;

[0033] (2) Assemble an evaporation device for fluorine-modified graphene oxide-based composite aerogel dihedrals;

[0034] (3) Place the evaporation device at a solar intensity of 1 kW·m -2 The experiment was conducted, and the mass change curve of the device was recorded in real time using an electronic balance.

[0035] The salt resistance and stain resistance properties of the prepared fluorine-modified graphene oxide-based composite aerogel were tested, and the experimental results are as follows:

[0036] Under conditions of one sun, the evaporation rate reached 1.05 kg·m³. -2 ·h -1 When the NaCl solution concentration is below 8 wt%, the fluorine-modified graphene oxide-based composite aerogel dihedron can withstand salt for 8 hours. Even when the NaCl solution concentration is 10 wt%, salt begins to precipitate on the surface of the fluorine-modified graphene oxide-based composite aerogel dihedron after 4 hours, and only a small amount of salt crystals precipitate after 8 hours. It has good water-oil separation capability when using oil-in-water emulsion as raw water.

[0037] Figure 1 The optical photographs of the dihedral of the fluorine-modified graphene oxide-based composite aerogel show that it has good light absorption in the visible light region.

[0038] Figure 2 (a) Water contact angle and (b) Oil contact angle of the lower layer of the dihedral of the fluorine-modified graphene oxide-based composite aerogel; (c) Water contact angle and (d) Oil contact angle of the upper layer of the dihedral of the fluorine-modified graphene oxide-based composite aerogel. Figure 2 It can be seen that only the upper layer is modified to be hydrophobic and oleophobic, while the lower layer is hydrophilic.

[0039] Figure 3 The evaporation curves of the dihedral of the fluorine-modified graphene oxide-based composite aerogel can be used to calculate the evaporation rate.

[0040] Figure 4 Optical photographs showing the changes in salt crystallization on the surface of fluorine-modified graphene oxide-based composite aerogel over time, using (a) 3.5 wt%, (b) 5 wt%, (c) 8 wt%, and (d) 10 wt% NaCl solutions as raw water, demonstrate that it has good salt resistance, with no salt crystallization occurring on the light-absorbing surface after long-term operation.

[0041] Figure 5 The left image in the middle is a photo before purification, and the right image is a photo after purification. Figure 5 This indicates that the fluorine-modified graphene oxide-based composite aerogel dihedral has good oil-water separation capability.

[0042] Example 2

[0043] A method for preparing a fluorine-modified graphene oxide-based composite aerogel dihedron includes the following steps:

[0044] Step 1: Prepare an aqueous solution of graphene oxide with a concentration of 10 mg / mL and an aqueous solution of chitosan with a concentration of 1 mg / mL;

[0045] Step 2: Mix the graphene oxide aqueous solution and the chitosan aqueous solution at a solute mass ratio of 2:1 for 30 min, sonicate for 40 min to obtain a dispersion; then transfer it to a mold and freeze it in a refrigerator.

[0046] Step 3: Freeze-dry the frozen dispersion for 48 hours, and then vacuum-dry it at 60°C for 12 hours to obtain an aerogel;

[0047] Step 4: The clean nonwoven fabric is impregnated with a hexane solution of 1H,1H,2H,2H-perfluorodecyltrichlorosilane at a concentration of 10 vol%. The impregnated nonwoven fabric is placed on the surface of the aerogel and left at ambient temperature for 3 hours. Then it is dried at 70°C for 6 hours to obtain a fluorine-modified graphene oxide-based composite aerogel dihedron.

[0048] Performance testing:

[0049] (1) Prepare NaCl solutions with concentrations of 3.5, 5, 8 and 10 wt%;

[0050] (2) Assemble an evaporation device for fluorine-modified graphene oxide-based composite aerogel dihedrals;

[0051] (3) Place the evaporation device at a solar intensity of 1 kW·m -2 The experiment was conducted, and the mass change curve of the device was recorded in real time using an electronic balance.

[0052] The salt resistance and stain resistance properties of the prepared fluorine-modified graphene oxide-based composite aerogel were tested, and the experimental results are as follows:

[0053] Under conditions of one sun, the evaporation rate reached 0.85 kg·m³. -2 ·h -1 When the NaCl solution concentration is below 8 wt%, the fluorine-modified graphene oxide-based composite aerogel dihedron can resist salt for 8 hours. When the NaCl solution concentration is 10 wt%, salt begins to precipitate on the surface of the fluorine-modified graphene oxide-based composite aerogel dihedron after 5 hours. It has good water-oil separation capability when using oil-in-water emulsion as raw water.

[0054] Example 3

[0055] A method for preparing a fluorine-modified graphene oxide-based composite aerogel dihedron includes the following steps:

[0056] Step 1: Prepare an aqueous solution of graphene oxide with a concentration of 3 mg / mL and an aqueous solution of sodium cellulose with a concentration of 4 mg / mL;

[0057] Step 2: Mix the aqueous solution of graphene oxide and the aqueous solution of sodium cellulose at a solute mass ratio of 3:2 for 15 min, sonicate for 20 min to obtain a dispersion; then transfer it to a mold and freeze it in a refrigerator.

[0058] Step 3: Freeze-dry the frozen dispersion for 30 hours, and then vacuum-dry it at 80°C for 10 hours to obtain an aerogel;

[0059] Step 4: Impregnate a clean nonwoven fabric with a hexane solution of 1H,1H,2H,2H-perfluorodecyltrichlorosilane at a concentration of 5 vol%. Place the impregnated nonwoven fabric on the surface of the aerogel and leave it at ambient temperature for 5 hours. Then dry it at 80°C for 5 hours to obtain a fluorine-modified graphene oxide-based composite aerogel dihedron.

[0060] Performance testing:

[0061] (1) Prepare NaCl solutions with concentrations of 3.5, 5, 8 and 10 wt%;

[0062] (2) Assemble an evaporation device for fluorine-modified graphene oxide-based composite aerogel dihedrals;

[0063] (3) Place the evaporation device at a solar intensity of 1 kW·m -2 The experiment was conducted, and the mass change curve of the device was recorded in real time using an electronic balance.

[0064] The salt resistance and stain resistance properties of the prepared fluorine-modified graphene oxide-based composite aerogel were tested, and the experimental results are as follows:

[0065] Under conditions of one sun, the evaporation rate reached 0.9 kg·m³. -2 ·h-1 When the NaCl solution concentration is below 8 wt%, the fluorine-modified graphene oxide-based composite aerogel dihedron can resist salt for 8 hours. When the NaCl solution concentration is 10 wt%, salt begins to precipitate on the surface of the fluorine-modified graphene oxide-based composite aerogel dihedron after 7 hours. It has good water-oil separation capability when using oil-in-water emulsion as raw water.

[0066] Example 4

[0067] A method for preparing a fluorine-modified graphene oxide-based composite aerogel dihedron includes the following steps:

[0068] Step 1: Prepare an aqueous solution of graphene oxide with a concentration of 1 mg / mL and an aqueous solution of chitosan with a concentration of 6 mg / mL;

[0069] Step 2: Mix the graphene oxide aqueous solution and the chitosan aqueous solution at a solute mass ratio of 6:5 for 20 min, sonicate for 25 min to obtain a dispersion; then transfer it to a mold and freeze it in a refrigerator.

[0070] Step 3: Freeze-dry the frozen dispersion for 36 hours, and then vacuum-dry it at 100°C for 6 hours to obtain an aerogel;

[0071] Step 4: The clean nonwoven fabric is impregnated with a hexane solution of 1H,1H,2H,2H-perfluorodecyltrichlorosilane at a concentration of 6 vol%. The impregnated nonwoven fabric is placed on the surface of the aerogel and left at ambient temperature for 6 hours. Then it is dried at 90°C for 3 hours to obtain a fluorine-modified graphene oxide-based composite aerogel dihedron.

[0072] Performance testing:

[0073] (1) Prepare NaCl solutions with concentrations of 3.5, 5, 8 and 10 wt%;

[0074] (2) Assemble an evaporation device for fluorine-modified graphene oxide-based composite aerogel dihedrals;

[0075] (3) Place the evaporation device at a solar intensity of 1 kW·m -2 The experiment was conducted, and the mass change curve of the device was recorded in real time using an electronic balance.

[0076] The salt resistance and stain resistance properties of the prepared fluorine-modified graphene oxide-based composite aerogel were tested, and the experimental results are as follows:

[0077] Under conditions of one sun, the evaporation rate reached 0.75 kg·m³. -2 ·h -1Using NaCl solutions with concentrations of 3.5%, 5%, 8%, and 10 wt% as raw water, the bihedral of fluorine-modified graphene oxide-based composite aerogels can withstand salt for 8 hours; using oil-in-water emulsions as raw water, they exhibit good water-oil separation capabilities.

[0078] Example 5

[0079] A method for preparing a fluorine-modified graphene oxide-based composite aerogel dihedron includes the following steps:

[0080] Step 1: Prepare an aqueous solution of graphene oxide with a concentration of 5 mg / mL and an aqueous solution of sodium cellulose with a concentration of 8 mg / mL;

[0081] Step 2: Mix the aqueous solution of graphene oxide and the aqueous solution of sodium cellulose at a solute mass ratio of 1:10 for 25 min, sonicate for 30 min to obtain a dispersion; then transfer it to a mold and freeze it in a refrigerator.

[0082] Step 3: Freeze-dry the frozen dispersion for 40 hours, and then vacuum-dry it at 150°C for 2 hours to obtain an aerogel;

[0083] Step 4: Soak a clean nonwoven fabric in a hexane solution of 1H,1H,2H,2H-perfluorodecyltrichlorosilane at a concentration of 1 vol%. Place the soaked nonwoven fabric on the surface of the aerogel and leave it at ambient temperature for 8 hours. Then dry it at 120°C for 1 hour to obtain a fluorine-modified graphene oxide-based composite aerogel dihedron.

[0084] Performance testing:

[0085] (1) Prepare NaCl solutions with concentrations of 3.5, 5, 8 and 10 wt%;

[0086] (2) Assemble an evaporation device for fluorine-modified graphene oxide-based composite aerogel dihedrals;

[0087] (3) Place the evaporation device at a solar intensity of 1 kW·m -2 The experiment was conducted, and the mass change curve of the device was recorded in real time using an electronic balance.

[0088] The salt resistance and stain resistance properties of the prepared fluorine-modified graphene oxide-based composite aerogel were tested, and the experimental results are as follows:

[0089] Under conditions of one sun, the evaporation rate reached 1.1 kg·m³. -2 ·h -1 Using NaCl solutions with concentrations of 3.5%, 5%, 8%, and 10 wt% as raw water, the bihedral of fluorine-modified graphene oxide-based composite aerogels can withstand salt for 8 hours; using oil-in-water emulsions as raw water, they exhibit good water-oil separation capabilities.

[0090] Example 6

[0091] A method for preparing a fluorine-modified graphene oxide-based composite aerogel dihedron includes the following steps:

[0092] Step 1: Prepare an aqueous solution of graphene oxide with a concentration of 10 mg / mL and an aqueous solution of sodium cellulose with a concentration of 5 mg / mL;

[0093] Step 2: Mix the aqueous solution of graphene oxide and the aqueous solution of sodium cellulose at a solute mass ratio of 10:1 for 30 min, sonicate for 140 min to obtain a dispersion; then transfer it to a mold and freeze it in a refrigerator.

[0094] Step 3: Freeze-dry the frozen dispersion for 30 hours, and then vacuum-dry it at 60°C for 12 hours to obtain an aerogel;

[0095] Step 4: Soak a clean nonwoven fabric in a hexane solution of 1H,1H,2H,2H-perfluorodecyltrichlorosilane at a concentration of 1 vol%. Place the soaked nonwoven fabric on the surface of the aerogel and leave it at ambient temperature for 3 hours. Then dry it at 60°C for 6 hours to obtain a fluorine-modified graphene oxide-based composite aerogel dihedron.

[0096] Performance testing:

[0097] (1) Prepare NaCl solutions with concentrations of 3.5, 5, 8 and 10 wt%;

[0098] (2) Assemble an evaporation device for fluorine-modified graphene oxide-based composite aerogel dihedrals;

[0099] (3) Place the evaporation device at a solar intensity of 1 kW·m -2 The experiment was conducted, and the mass change curve of the device was recorded in real time using an electronic balance.

[0100] The salt resistance and stain resistance properties of the prepared fluorine-modified graphene oxide-based composite aerogel were tested, and the experimental results are as follows:

[0101] Under conditions of one sun, the evaporation rate reached 0.7 kg·m³. -2 ·h -1 Using NaCl solutions with concentrations of 3.5%, 5%, 8%, and 10 wt% as raw water, the bihedral of fluorine-modified graphene oxide-based composite aerogels can withstand salt for 8 hours; using oil-in-water emulsions as raw water, they exhibit good water-oil separation capabilities.

[0102] Comparative Example 1

[0103] A method for preparing a graphene oxide-based composite aerogel dihedron includes the following steps:

[0104] Step 1: Prepare an aqueous solution of graphene oxide with a concentration of 6 mg / mL and an aqueous solution of sodium cellulose with a concentration of 10 mg / mL;

[0105] Step 2: Mix the aqueous solution of graphene oxide and the aqueous solution of sodium cellulose at a solute mass ratio of 3:1 for 5 min, sonicate for 10 min to obtain a dispersion; then transfer it to a mold and freeze it in a refrigerator.

[0106] Step 3: Freeze-dry the frozen dispersion for 48 hours, and then vacuum-dry it at 130°C for 2 hours to obtain a graphene oxide-based composite aerogel dihedron.

[0107] Performance testing:

[0108] (1) Prepare NaCl solutions with concentrations of 3.5, 5, 8 and 10 wt%;

[0109] (2) Assemble an evaporation device for graphene oxide-based aerogel dihedrals;

[0110] (3) Place the evaporation device at a solar intensity of 1 kW·m -2 The experiment was conducted, and the mass change curve of the device was recorded in real time using an electronic balance.

[0111] The salt and dirt resistance properties of the prepared graphene oxide-based composite aerogel were tested, and the experimental results are as follows:

[0112] Under conditions of one sun, the evaporation rate reached 1.03 kg·m³. -2 ·h -1 However, even when the NaCl solution concentration is as low as 3.5 wt%, the graphene oxide-based aerogel dihedral begins to precipitate salt after 3 hours of operation; using oil-in-water emulsion as the raw water, it does not have good water-oil separation capability.

[0113] Comparative Example 2

[0114] A method for preparing a fluorine-modified graphene oxide-based aerogel dihedron includes the following steps:

[0115] Step 1: Prepare a 6 mg / mL aqueous solution of graphene oxide, sonicate for 10 min, then transfer it to a mold and freeze it in a refrigerator;

[0116] Step 2: Freeze-dry the frozen dispersion for 48 hours, and then vacuum-dry it at 130°C for 2 hours;

[0117] Step 3: Soak a clean nonwoven fabric in a hexane solution of 1H,1H,2H,2H-perfluorodecyltrichlorosilane at a concentration of 1 vol%. Place the soaked nonwoven fabric on the surface of the aerogel and leave it at ambient temperature for 2 hours. Then dry it at 60°C for 1 hour to obtain a fluorine-modified graphene oxide-based aerogel dihedron.

[0118] Performance testing:

[0119] (1) Prepare NaCl solutions with concentrations of 3.5, 5, 8 and 10 wt%;

[0120] (2) Assemble an evaporation device for fluorine-modified graphene oxide aerogel dihedrals;

[0121] (3) Place the evaporation device at a solar intensity of 1 kW·m -2 The experiment was conducted, and the mass change curve of the device was recorded in real time using an electronic balance.

[0122] The salt and dirt resistance properties of the prepared fluorine-modified graphene oxide-based aerogel dihedron were tested, and the experimental results are as follows:

[0123] Under conditions of one sun, the evaporation rate is only 0.40 kg·m³. -2 ·h -1 When the NaCl solution concentration is below 8 wt%, only a small amount of salt crystals precipitate after 6 hours; using oil-in-water emulsion as the raw water, it has good water-oil separation capability.

[0124] Comparative Example 3

[0125] A method for preparing a fluorine-modified graphene oxide-based composite aerogel dihedron includes the following steps:

[0126] Step 1: Prepare an aqueous solution of graphene oxide with a concentration of 6 mg / mL and an aqueous solution of sodium cellulose with a concentration of 10 mg / mL;

[0127] Step 2: Mix the aqueous solution of graphene oxide and the aqueous solution of sodium cellulose at a solute mass ratio of 3:1 for 5 min, sonicate for 10 min to obtain a dispersion; then transfer it to a mold and freeze it in a refrigerator.

[0128] Step 3: Freeze-dry the frozen dispersion for 48 hours, and then vacuum-dry it at 130°C for 2 hours to obtain an aerogel;

[0129] Step 4: Soak a clean nonwoven fabric in a hexane solution of 1H,1H,2H,2H-perfluorodecyltrichlorosilane at a concentration of 1 vol%. Place the soaked nonwoven fabric on the surface of the aerogel and leave it at ambient temperature for 1 hour. Then dry it at 60°C for 1 hour to obtain a fluorine-modified graphene oxide-based composite aerogel dihedron.

[0130] Performance testing:

[0131] (4) Prepare NaCl solutions with concentrations of 3.5%, 5%, 8%, and 10 wt%;

[0132] (5) Assemble an evaporation device for fluorine-modified graphene oxide-based composite aerogel dihedrals;

[0133] (6) Place the evaporation device at a solar intensity of 1 kW·m -2 The experiment was conducted, and the mass change curve of the device was recorded in real time using an electronic balance.

[0134] The salt resistance and stain resistance properties of the prepared fluorine-modified graphene oxide-based composite aerogel were tested, and the experimental results are as follows:

[0135] Under conditions of one sun, the evaporation rate reached 0.90 kg·m³. -2 ·h -1 When the NaCl solution concentration is 3.5 wt%, the fluorine-modified graphene oxide-based composite aerogel dihedron precipitates salt after 7 hours of operation; using oil-in-water emulsion as the raw water, it does not have good water-oil separation capability.

[0136] In summary, the fluorine-modified graphene oxide-based composite aerogel prepared by this invention has a hydrophobic upper layer and a hydrophilic lower layer, achieving resistance to high-concentration salt water while exhibiting good oil-water separation performance.

Claims

1. A method for preparing a fluorine-modified graphene oxide-based composite aerogel dihedron, characterized in that, Includes the following steps: (1) Prepare aqueous solutions of graphene oxide and sodium cellulose or chitosan; (2) Mix the aqueous solution of graphene oxide and the aqueous solution of sodium cellulose, or mix the aqueous solution of graphene oxide and the aqueous solution of chitosan to obtain a mixture; (3) The mixture was freeze-dried and then vacuum-dried to obtain an aerogel; (4) The nonwoven fabric is impregnated with an organic solution containing fluorochlorosilane, the impregnated nonwoven fabric is placed on the surface of the aerogel, left to stand, and dried to obtain the product. The concentration of the organic solution containing fluorochlorosilane is 1-10 vol%; the standing time is 2-8 h. The fluorine-modified graphene oxide-based aerogel dihedron includes a graphene oxide-based composite aerogel, the main body of which comprises graphene oxide and sodium cellulose or chitosan; one side of the graphene oxide-based composite aerogel is modified with fluorochlorosilane to provide hydrophobic and oleophobic properties.

2. The method for preparing fluorine-modified graphene oxide-based aerogel dihedrons according to claim 1, characterized in that, In step (1), the concentration of the aqueous solution of graphene oxide and the concentration of the aqueous solution of sodium cellulose or chitosan are both 1-10 mg / mL.

3. The method for preparing fluorine-modified graphene oxide-based aerogel dihedrons according to claim 1, characterized in that, In step (2), the mass ratio of the solutes in the graphene oxide solution and the sodium cellulose solution or chitosan solution is 1:10 to 10:

1.

4. The method for preparing fluorine-modified graphene oxide-based aerogel dihedrons according to claim 1, characterized in that, In step (4), the fluorochlorosilane is 1H,1H,2H,2H-perfluorodecyltrichlorosilane.

5. The method for preparing fluorine-modified graphene oxide-based aerogel dihedrons according to claim 1, characterized in that, In step (3), the freeze-drying time is 24-48 h.

6. The method for preparing fluorine-modified graphene oxide-based aerogel dihedrons according to claim 1, characterized in that, In step (3), the vacuum drying temperature is 60-150℃ and the time is 2-12 h.

7. The application of a fluorine-modified graphene oxide-based aerogel dihedral obtained by the method of claim 1 in the field of seawater desalination.

Images