Zwitterionic hydrogel-engineered graphene aerogel capable of high-salt resistance and efficient seawater evaporation and preparation method and application thereof

Abstract

The application discloses a zwitterionic hydrogel graphene aerogel capable of realizing high-salt resistance and efficient seawater evaporation, and a preparation method and application thereof; the zwitterionic hydrogel graphene aerogel is obtained by using graphene aerogel as a skeleton and covering the skeleton with a zwitterionic gel film through surface modification, so that the zwitterionic hydrogel graphene aerogel is obtained; the gel system constructed by the application has excellent water evaporation rate, and based on the counterion effect of the zwitterionic hydrogel and the vertical channel structure of the graphene aerogel, salt crystallization resistance in super-high concentration brine can be realized, long-time stable evaporation and fresh water collection can be realized, and the application potential in the field of solar interface water evaporation is shown.

Description

Technical Field

[0001] This invention relates to the fields of solar interface water evaporation and water purification, and in particular to a zwitterionic hydrogel engineered graphene aerogel capable of high-salt and high-efficiency seawater evaporation, its preparation method and application. Background Technology

[0002] Currently, effectively utilizing solar energy to produce clean water from seawater or even industrial wastewater is a promising method for solving water shortages.

[0003] However, the efficient operation of an evaporator largely depends on its structural design, the selection of photothermal materials, and the long-term stability of the evaporation equipment. During long-term operation, some challenges are unavoidable, particularly the balance between salt crystallization at the evaporation interface and evaporation efficiency, which is one of the core challenges. Improving evaporation efficiency typically involves enhancing photothermal conversion and localized heat concentration, which can lead to rapid salt accumulation near the evaporation interface. Traditional evaporators, such as those utilizing porous media, exhibit limited salt tolerance in saline environments. High evaporation rates caused by capillary-induced water transport often accelerate salt deposition within the evaporation layer, leading to crystal formation. This process not only hinders water transport but also impairs light absorption, thus reducing efficiency and potentially damaging the evaporation device.

[0004] Therefore, existing interfacial solar evaporation devices still have great potential for improvement in balancing efficient evaporation and salt crystallization. There is an urgent need to develop an evaporation device that can achieve efficient seawater evaporation and purification, while preventing salt crystallization at the interface after long-term operation. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes an amphoteric hydrogel engineered graphene aerogel capable of high-salt tolerance and efficient seawater evaporation, along with its preparation method and applications.

[0006] This invention employs graphene aerogel as the framework of the evaporation device, and grows zwitterionic gel in situ on the porous structure of the graphene aerogel to construct a zwitterionic hydrogel-engineered graphene aerogel evaporator. In this design system, the graphene aerogel has vertically aligned microchannels for rapid water transport and photothermal conversion, and works synergistically with the zwitterionic hydrogel skin, utilizing the anti-polyelectrolyte effect of the zwitterionic gel to create a dynamic water ion network.

[0007] It is worth noting that, due to the rational pore structure design and effective distribution of the hydrogel membrane, this dual-adjustment design enables the evaporator to achieve a solar evaporation rate of 5.026 kg m³ under a single solar irradiation. -2 h -1Meanwhile, in 15wt% brine, the solar radiation energy maintained an efficiency of 98.5% after 5 cycles. In 20wt% high-concentration brine, after continuous evaporation for 8 hours and 5 cycles, no salt crystallization occurred.

[0008] The technical solution of the present invention is as follows:

[0009] A method for preparing zwitterionic hydrogel engineered graphene aerogel includes the following steps:

[0010] (1) Disperse zwitterionic monomers, photoinitiators and crosslinking agents in deionized water to obtain zwitterionic prepolymer solution;

[0011] The zwitterionic monomers are selected from: 2-methacryloyloxyethyl phosphocholine (MPC), 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate (CBMA), [3-(methacryloylamino)propyl]dimethyl(3-thiopropyl)ammonium hydroxide (SBAA), 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonate inner salt (SBMA), dimethyl-(4-vinylphenyl)propanesulfonate ammonium (DVBAPS), or 3-(1-(4-vinylbenzyl)-1H-imidazol-3-onthium)propane-1-sulfonate (VBIPS), etc., in which the same repeating unit contains equal amounts of anionic and cationic groups, preferably 3-(1-(4-vinylbenzyl)-1H-imidazol-3-onthium)propane-1-sulfonate (VBIPS);

[0012] The photoinitiator is selected from: 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (2959), 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, α,α-dimethoxy-α-phenylacetophenone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone or phenyl-2,4,6-trimethylbenzoyl lithium phosphite, preferably 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (2959);

[0013] The crosslinking agent is selected from: ethylene dimethacrylate, N,N'-methylenebisacrylamide, N,N'-dimethylacrylamide, preferably N,N'-methylenebisacrylamide;

[0014] In the preferred zwitterionic prepolymer solution, the zwitterionic monomer concentration is 0.1–10 mmol / mL, the mass fraction of the photoinitiator is 0.1–1%, and the mass fraction of the crosslinking agent is 0.01–1%.

[0015] (2) The graphene aerogel was treated with O2 plasma, then soaked in silane coupling agent solution, and dried to obtain modified graphene aerogel.

[0016] The graphene aerogel is selected from: graphene oxide aerogel, reduced graphene aerogel, reduced graphene oxide aerogel, with reduced graphene aerogel being preferred.

[0017] The preferred O2 plasma treatment time is 1–60 min;

[0018] The silane coupling agent is selected from: 3-(methacryloyloxy)propyltrimethoxysilane, 3-triethoxysilyl-1-propylamine, γ-glycidoxypropyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimeth(eth)oxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, preferably 3-(methacryloyloxy)propyltrimethoxysilane;

[0019] The silane coupling agent solution is prepared by mixing silane coupling agent, ethanol, deionized water, and acetic acid. The concentration of silane coupling agent in the silane coupling agent solution is 0.01–5 mol / L.

[0020] Soaking time: 1–60 min; Drying time: 1–24 h.

[0021] (3) The modified graphene aerogel obtained in step (2) is immersed in the zwitterionic prepolymer liquid obtained in step (1), and then taken out and subjected to ultraviolet light irradiation to initiate a polymerization reaction to obtain zwitterionic hydrogel engineering graphene aerogel.

[0022] The modified graphene aerogel can be partially or completely immersed in a zwitterionic prepolymer solution, with the preferred immersion time being 1 to 60 minutes.

[0023] The polymerization reaction was carried out at room temperature for 0.5–12 hours.

[0024] This invention relates to zwitterionic hydrogels and engineered graphene aerogels prepared by the above-mentioned method.

[0025] The zwitterionic hydrogel engineered graphene aerogel described in this invention can be applied to seawater desalination and purification at the solar interface, as detailed below:

[0026] The implementation method of seawater evaporation is as follows: zwitterionic hydrogel-engineered graphene aerogel is placed in a container filled with seawater. The zwitterionic hydrogel-engineered graphene aerogel can float on the seawater, with its lower end in full contact with the seawater and its upper end exposed to the air to absorb sunlight. Xenon lamps are used to simulate sunlight irradiation, and the mass change and rate of change of the device during the evaporation process are monitored by an electronic balance to evaluate the solar seawater evaporation efficiency of the device. At the same time, a transparent support shell is set outside the container to condense water vapor and collect freshwater.

[0027] Wastewater purification implementation method: Replace the seawater in the container during the above seawater evaporation process with oily seawater stained with Rhodamine B, and the subsequent operations are the same as the above implementation method.

[0028] The innovative aspects and technical principles of this invention are as follows:

[0029] Existing evaporation devices that combine graphene aerogel and zwitterionic hydrogel typically involve adding graphene powder to a zwitterionic precursor solution, using the graphene powder as a photothermal absorber. This application, however, combines graphene aerogel with a fully vertically porous structure with a zwitterionic hydrogel, covering the aerogel surface with a hydrogel film to construct a zwitterionic engineered graphene aerogel evaporation device.

[0030] The evaporation device designed in this application, based on the vertical pore structure of graphene aerogel and the hydrogel film distributed on the pore structure, enables rapid transport of brine. Furthermore, the zwitterionic gel used in this application exhibits a stronger anti-polyelectrolyte effect compared to commercially available zwitterionic gels. The strong water transport capacity of the graphene aerogel, combined with the strong hydration capacity of the zwitterionic gel, enables resistance to salt crystallization and a high evaporation rate in high-salt environments. This application demonstrates innovation in both evaporator structure and material design.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] The zwitterionic hydrogel engineering graphene aerogel evaporation device designed in this invention is based on the anti-polyelectrolyte effect of zwitterionic polymers in salt solutions, which can effectively increase the hydration volume of the gel and enhance its hydration capacity, thereby reducing the evaporation rate of water. The graphene aerogel has excellent photothermal conversion capacity and light absorption capacity, while the vertical channels are conducive to the rapid transport of water, thus synergistically achieving a high evaporation rate and resistance to high salt environments.

[0033] The zwitterionic hydrogel engineered graphene aerogel of this invention can achieve an evaporation rate of 5.026 kg / m³ in seawater. -2 h -1Meanwhile, in 15wt% brine, the solar radiation energy maintained an efficiency of 98.5% after 5 cycles. In 20wt% high-concentration brine, after continuous evaporation for 8 hours and 5 cycles, no salt crystallization occurred. Attached Figure Description

[0034] Figure 1 Swelling properties of zwitterionic hydrogels with different molar numbers prepared in Example 1 in seawater.

[0035] Figure 2 : Schematic diagram of the preparation of zwitterionic hydrogel engineering graphene aerogel in this invention.

[0036] Figure 3 Example 2: Seawater evaporation performance of zwitterionic hydrogels prepared with different molar numbers of graphene aerogels.

[0037] Figure 4 : The seawater evaporation performance of the zwitterionic hydrogel prepared in Example 3 with different coverage of graphene aerogel.

[0038] Figure 5 Example 4: Seawater evaporation performance of five zwitterionic hydrogels with different pore sizes prepared as engineered graphene aerogels.

[0039] Figure 6 Example 5: Long-term water evaporation performance of zwitterionic hydrogel engineered graphene aerogel in salt water of different concentrations.

[0040] Figure 7 Example 6: UV absorption spectra of water collected before and after evaporation in seawater stained with Rhodamine B, prepared as zwitterionic hydrogel engineered graphene aerogel.

[0041] Figure 8 : Long-term water evaporation performance of the zwitterionic hydrogel engineered graphene aerogel prepared in Example 7 in oily seawater. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the following description is only the most preferred embodiment of the present invention and should not be regarded as a limitation on the scope of protection of the present invention.

[0043] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0044] Example 1

[0045] First, 0.305 g (1 mmol) / 0.61 g (2 mmol) / 0.915 g (3 mmol) VBIPS, 0.001 g (0.0065 mmol) N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (photoinitiator) were dispersed in 0.97 mL of deionized water and sonicated at 40 kHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel. The solution was then injected into a mold using a syringe. The reaction system was then photocured under 365 nm UV light for 3.5 h to obtain Pvbips gel. The obtained pure zwitterionic gel was completely immersed in 25 mL of natural seawater to test its swelling properties in seawater to verify the anti-polyelectrolyte effect of zwitterions. Figure 1 ).

[0046] Example 2

[0047] First, 0.305 g (1 mmol) / 0.61 g (2 mmol) / 0.915 g (3 mmol) VBIPS, 0.001 g (0.0065 mmol) N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (photoinitiator) were dispersed in 0.97 mL of deionized water and sonicated at 40 kHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel.

[0048] The graphene aerogel used is cylindrical, with a base radius of 10 mm, a height of 5 mm, and a volume of 1.57 * 10^6 mm. -6 m 3 The graphene aerogel (with an average pore size of 400 μm) was placed in the instrument and treated with O2 plasma for 10 minutes. 4 ml of 3-(methacryloyloxy)propyltrimethoxysilane was added to a mixed solvent of 18 ml anhydrous ethanol and 2 ml deionized water, along with 1 ml acetic acid. The mixture was sonicated for 5 minutes to obtain a silane coupling agent solution. The treated graphene aerogel was then immersed in the silane coupling agent solution for 30 minutes, removed, and dried in a 50°C oven for 8 hours. The dried graphene aerogel was then immersed in a zwitterionic polymer prepolymer solution for 30 minutes, removed, and photocured under 365 nm UV light at room temperature for 4 hours to obtain a zwitterionic hydrogel engineered graphene aerogel. Figure 2 )

[0049] The seawater evaporation experiment of the above-mentioned zwitterionic hydrogel-engineered graphene aerogel was conducted under laboratory conditions of 25°C and 50% RH. Irradiation was performed using a solar simulator to simulate natural sunlight (radiation intensity of 1 kW m²). -2 The zwitterionic hydrogel engineered graphene aerogel was placed in a container filled with seawater, with its lower end fully immersed in the seawater and its upper end exposed to air to absorb sunlight. Under simulated sunlight irradiation, the solar-powered seawater evaporation efficiency of the aerogel was evaluated by monitoring the mass change and its rate of change during the evaporation process using an electronic balance. Simultaneously, a transparent support shell was installed outside the container to condense water vapor and collect freshwater. Figure 3 )

[0050] Example 3

[0051] First, 0.61 g (2 mmol) VBIPS, 0.001 g (0.0065 mmol) N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (photoinitiator) were dispersed in 0.97 mL of deionized water and sonicated at 40 kHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel.

[0052] The graphene aerogel used is cylindrical, with a base radius of 10 mm, a height of 5 mm, and a volume of 1.57 * 10^6 mm. -6 m 3 The graphene aerogel (with an average pore size of 400 μm) was placed in the instrument and treated with O2 plasma for 10 minutes. 4 ml of 3-(methacryloyloxy)propyltrimethoxysilane was added to a mixed solvent of 18 ml anhydrous ethanol and 2 ml deionized water, along with 1 ml acetic acid. The mixture was sonicated for 5 minutes to obtain a silane coupling agent solution. The treated graphene aerogel was then immersed in the silane coupling agent solution for 30 minutes, removed, and dried in a 50°C oven for 8 hours.

[0053] One portion of the dried graphene aerogel was immersed in a zwitterionic polymer prepolymer solution for 30 minutes, then removed and photocured at room temperature under 365 nm UV light for 4 hours to obtain a zwitterionic hydrogel engineered graphene aerogel partially wetted (wetting volume accounting for 1 / 3 of the total volume) with zwitterionic gel. Another portion of the dried graphene aerogel was completely immersed in the zwitterionic polymer prepolymer solution and photocured at room temperature under 365 nm UV light for 4 hours to obtain a zwitterionic hydrogel engineered graphene aerogel completely filled with zwitterionic aerogel. Figure 2 )

[0054] The seawater evaporation experiment of the above-mentioned zwitterionic hydrogel-engineered graphene aerogel was conducted under laboratory conditions of 25°C and 50% RH. Irradiation was performed using a solar simulator to simulate natural sunlight (radiation intensity of 1 kW m²). -2 The zwitterionic hydrogel engineered graphene aerogel was placed in a container filled with seawater, with its lower end fully immersed in the seawater and its upper end exposed to air to absorb sunlight. Under simulated sunlight irradiation, the solar-powered seawater evaporation efficiency of the aerogel was evaluated by monitoring the mass change and its rate of change during the evaporation process using an electronic balance. Simultaneously, a transparent support shell was installed outside the container to condense water vapor and collect freshwater. Figure 4 )

[0055] Example 4

[0056] First, 0.61 g (2 mmol) VBIPS, 0.001 g (0.0065 mmol) N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (photoinitiator) were dispersed in 0.97 mL of deionized water and sonicated at 40 kHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel.

[0057] Five different aperture sizes ( Figure 5 The average pore sizes of graphene aerogels No. 1-5 were 100 μm, 240 μm, 370 μm, 410 μm, and 460 μm, respectively. These graphene aerogels were placed in an instrument and treated with O2 plasma for 10 minutes. 4 ml of 3-(methacryloyloxy)propyltrimethoxysilane was added to a mixed solvent of 18 ml anhydrous ethanol and 2 ml deionized water, along with 1 ml of acetic acid. The mixture was sonicated for 5 minutes to obtain a silane coupling agent solution. The treated graphene aerogel was then immersed in the silane coupling agent solution for 30 minutes, removed, and dried in a 50°C oven for 8 hours. The dried graphene aerogel was then immersed in a zwitterionic polymer prepolymer solution for 30 minutes, removed, and photocured under 365 nm UV light at room temperature for 4 hours to obtain zwitterionic hydrogel engineering graphene aerogel. Figure 2 )

[0058] The seawater evaporation experiment of the above-mentioned zwitterionic hydrogel-engineered graphene aerogel was conducted under laboratory conditions of 25°C and 50% RH. Irradiation was performed using a solar simulator to simulate natural sunlight (radiation intensity of 1 kW m²). -2The zwitterionic hydrogel engineered graphene aerogel was placed in a container filled with seawater, with its lower end fully immersed in the seawater and its upper end exposed to air to absorb sunlight. Under simulated sunlight irradiation, the solar-powered seawater evaporation efficiency of the aerogel was evaluated by monitoring the mass change and its rate of change during the evaporation process using an electronic balance. Simultaneously, a transparent support shell was installed outside the container to condense water vapor and collect freshwater. Figure 5 )

[0059] Example 5

[0060] First, 0.61 g (2 mmol) VBIPS, 0.001 g (0.0065 mmol) N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (photoinitiator) were dispersed in 0.97 mL of deionized water and sonicated at 40 kHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel.

[0061] The graphene aerogel used is cylindrical, with a base radius of 10 mm, a height of 5 mm, and a volume of 1.57 * 10^6 mm. -6 m 3 The graphene aerogel (with an average pore size of 400 μm) was placed in the instrument and treated with O2 plasma for 10 minutes. 4 ml of 3-(methacryloyloxy)propyltrimethoxysilane was added to a mixed solvent of 18 ml anhydrous ethanol and 2 ml deionized water, along with 1 ml acetic acid. The mixture was sonicated for 5 minutes to obtain a silane coupling agent solution. The treated graphene aerogel was then immersed in the silane coupling agent solution for 30 minutes, removed, and dried in a 50°C oven for 8 hours.

[0062] The dried graphene aerogel was immersed in a zwitterionic polymer prepolymer solution for 30 minutes, then removed and photocured under 365 nm UV light at room temperature for 4 hours to obtain a zwitterionic hydrogel engineered graphene aerogel partially wetted with zwitterionic polymer. Figure 2 )

[0063] The brine evaporation experiment of the above-mentioned zwitterionic hydrogel-engineered graphene aerogel was conducted in a laboratory under laboratory conditions of 25°C and 50% RH. Irradiation was performed using a solar simulator to simulate natural sunlight (radiation intensity of 1 kW m²). -2The zwitterionic hydrogel-engineered graphene aerogel was placed in a container filled with different water solutions (pure water / seawater / 10wt% sodium chloride / 15wt% sodium chloride / 20wt% sodium chloride solution), with the lower end fully immersed in the seawater and the upper end exposed to air to absorb sunlight. Under simulated sunlight irradiation, the mass change and its rate of change during the evaporation process were monitored using an electronic balance to evaluate the aerogel's solar-powered seawater evaporation efficiency. Simultaneously, a transparent support shell was installed outside the container to condense water vapor and collect freshwater. Figure 6 )

[0064] Example 6

[0065] First, 0.61 g (2 mmol) VBIPS, 0.001 g (0.0065 mmol) N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (photoinitiator) were dispersed in 0.97 mL of deionized water and sonicated at 40 kHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel.

[0066] The graphene aerogel used is cylindrical, with a base radius of 10 mm, a height of 5 mm, and a volume of 1.57 * 10^6 mm. -6 m 3 The graphene aerogel (with an average pore size of 400 μm) was placed in the instrument and treated with O2 plasma for 10 minutes. 4 ml of 3-(methacryloyloxy)propyltrimethoxysilane was added to a mixed solvent of 18 ml anhydrous ethanol and 2 ml deionized water, along with 1 ml acetic acid. The mixture was sonicated for 5 minutes to obtain a silane coupling agent solution. The treated graphene aerogel was then immersed in the silane coupling agent solution for 30 minutes, removed, and dried in a 50°C oven for 8 hours.

[0067] The dried graphene aerogel was immersed in a zwitterionic polymer prepolymer solution for 30 minutes, then removed and photocured under 365 nm UV light at room temperature for 4 hours to obtain a zwitterionic hydrogel engineered graphene aerogel partially wetted with zwitterionic polymer. Figure 2 )

[0068] The brine evaporation experiment of the above-mentioned zwitterionic hydrogel-engineered graphene aerogel was conducted in a laboratory under laboratory conditions of 25°C and 50% RH. Irradiation was performed using a solar simulator to simulate natural sunlight (radiation intensity of 1 kW m²). -2The zwitterionic hydrogel engineered graphene aerogel was placed in a container filled with seawater stained with the water-soluble reagent Rhodamine B, with the lower end fully immersed in the seawater and the upper end exposed to air to absorb sunlight. Under simulated sunlight irradiation, the solar-powered seawater evaporation efficiency of the aerogel was evaluated by monitoring the mass change and its rate during evaporation using an electronic balance. Simultaneously, a transparent support shell was installed outside the container to condense water vapor and perform ultraviolet absorption spectroscopy testing. Figure 7 )

[0069] Example 7

[0070] First, 0.61 g (2 mmol) VBIPS, 0.001 g (0.0065 mmol) N,N'-methylenebisacrylamide, and 0.01 g (0.04 mmol) 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (photoinitiator) were dispersed in 0.97 mL of deionized water and sonicated at 40 kHz for 5 min at room temperature to obtain a prepolymer solution of pure zwitterionic gel.

[0071] The graphene aerogel used is cylindrical, with a base radius of 10 mm, a height of 5 mm, and a volume of 1.57 * 10^6 mm. -6 m 3 The graphene aerogel (with an average pore size of 400 μm) was placed in the instrument and treated with O2 plasma for 10 minutes. 4 ml of 3-(methacryloyloxy)propyltrimethoxysilane was added to a mixed solvent of 18 ml anhydrous ethanol and 2 ml deionized water, along with 1 ml acetic acid. The mixture was sonicated for 5 minutes to obtain a silane coupling agent solution. The treated graphene aerogel was then immersed in the silane coupling agent solution for 30 minutes, removed, and dried in a 50°C oven for 8 hours.

[0072] The dried graphene aerogel was immersed in a zwitterionic polymer prepolymer solution for 30 minutes, then removed and photocured under 365 nm UV light at room temperature for 4 hours to obtain a zwitterionic hydrogel engineered graphene aerogel partially wetted with zwitterionic polymer. Figure 2 )

[0073] The brine evaporation experiment of the above-mentioned zwitterionic hydrogel-engineered graphene aerogel was conducted in a laboratory under laboratory conditions of 25°C and 50% RH. Irradiation was performed using a solar simulator to simulate natural sunlight (radiation intensity of 1 kW m²). -2The zwitterionic hydrogel engineered graphene aerogel was placed in a container of seawater containing silicone oil stained with oil-soluble reagent Oil Red O. The lower end of the aerogel was fully immersed in the seawater, while the upper end was exposed to air to absorb sunlight. Under simulated sunlight irradiation, the solar-powered seawater evaporation efficiency of the aerogel was evaluated by monitoring the mass change and its rate of change during the evaporation process using an electronic balance. Simultaneously, a transparent support shell was installed outside the container to condense water vapor and collect freshwater. Figure 8 )

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing zwitterionic hydrogel engineering graphene aerogel, characterized in that, Includes the following steps: (1) Disperse zwitterionic monomers, photoinitiators and crosslinking agents in deionized water to obtain zwitterionic prepolymer solution; The zwitterionic monomers are selected from: 2-methacryloyloxyethyl phosphocholine, 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate, [3-(methacryloylamino)propyl]dimethyl(3-thiopropyl)ammonium hydroxide, 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonate inner salt, dimethyl-(4-vinylphenyl)propanesulfonate ammonium, or 3-(1-(4-vinylbenzyl)-1H-imidazol-3-onthium)propane-1-sulfonate; (2) The graphene aerogel was treated with O2 plasma, then soaked in silane coupling agent solution, and dried to obtain modified graphene aerogel. The silane coupling agent is selected from: 3-(methacryloyloxy)propyltrimethoxysilane, 3-triethoxysilyl-1-propylamine, γ-glycidoxypropyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimeth(eth)oxysilane, and N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane; (3) The modified graphene aerogel obtained in step (2) is immersed in the zwitterionic prepolymer liquid obtained in step (1), and then taken out and subjected to ultraviolet light irradiation to initiate a polymerization reaction to obtain zwitterionic hydrogel engineering graphene aerogel.

2. The preparation method of zwitterionic hydrogel engineering graphene aerogel as described in claim 1, characterized in that, In step (1), the photoinitiator is selected from: 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, α,α-dimethoxy-α-phenylacetophenone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone or phenyl-2,4,6-trimethylbenzoyl lithium phosphite.

3. The preparation method of zwitterionic hydrogel engineering graphene aerogel as described in claim 1, characterized in that, In step (1), the crosslinking agent is selected from: ethylene dimethacrylate, N,N'-methylenebisacrylamide, and N,N'-dimethylacrylamide.

4. The method for preparing zwitterionic hydrogel engineering graphene aerogel as described in claim 1, characterized in that, In step (1), the zwitterionic prepolymer solution contains zwitterionic monomers at a concentration of 0.1–10 mmol / mL, photoinitiator at a mass fraction of 0.1–1%, and crosslinking agent at a mass fraction of 0.01–1%.

5. The method for preparing zwitterionic hydrogel engineering graphene aerogel as described in claim 1, characterized in that, In step (2), the O2 plasma treatment time is 1 to 60 minutes.

6. The method for preparing zwitterionic hydrogel engineering graphene aerogel as described in claim 1, characterized in that, In step (2), the silane coupling agent solution is prepared by mixing silane coupling agent, ethanol, deionized water and acetic acid. The concentration of silane coupling agent in the silane coupling agent solution is 0.01-5 mol / L. The soaking time in the silane coupling agent solution is 1-60 min and the drying time is 1-24 h.

7. The method for preparing zwitterionic hydrogel engineering graphene aerogel as described in claim 1, characterized in that, In step (3), the modified graphene aerogel is partially or completely immersed in zwitterionic prepolymer solution for 1 to 60 minutes.

8. The method for preparing zwitterionic hydrogel engineering graphene aerogel as described in claim 1, characterized in that, In step (3), the polymerization reaction is carried out at room temperature for 0.5 to 12 hours.

9. The zwitterionic hydrogel engineered graphene aerogel prepared by the preparation method according to any one of claims 1 to 8.

10. The application of zwitterionic hydrogel engineered graphene aerogel as described in claim 9 in seawater desalination and purification at the solar interface.

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