Silane modified graphene oxide / polyvinyl alcohol composite aerogel evaporator and preparation method and application thereof

Abstract

The invention provides a silane modified graphene oxide / polyvinyl alcohol composite aerogel evaporator and a preparation method and application thereof, and relates to the technical field of new energy materials.The preparation method comprises the steps that firstly, polyvinyl alcohol is dissolved in deionized water to form a uniform solution, absolute ethyl alcohol is added after cooling, and a PVA / ethyl alcohol-water cosolvent system is constructed; then, dispersing the graphene oxide powder into a cosolvent, and uniformly distributing the graphene oxide powder through ultrasonic treatment; then, (3-aminopropyl) trimethoxy silane is introduced; then, glutaraldehyde is added, standing is carried out at the room temperature, crosslinking and gelation processes are completed, and GO / SPH hydrogel is formed. And finally, soaking, washing and freeze-drying the obtained hydrogel to obtain the GO / SPH composite aerogel evaporator. According to the GO / SPH evaporator prepared through the method, the excellent photothermal conversion performance of the graphene oxide and the specific rapid water transportation and heat localization capacity of the PVA three-dimensional porous aerogel are utilized, and the extremely high water evaporation rate and solar energy conversion efficiency are achieved.

Description

Technical Field

[0001] This invention relates to the field of new energy materials technology, and in particular to a silane-modified graphene oxide / polyvinyl alcohol (GO / SPH) composite aerogel evaporator, its preparation method, and its application. Background Technology

[0002] Water security is the cornerstone of sustainable development for human society. However, with accelerated industrialization and continuous population growth, the global shortage of clean water resources is becoming increasingly severe. It is estimated that approximately 5 billion people are facing varying degrees of water stress, and this number is expected to continue to rise in the coming decades. By 2050, it is projected that two-thirds of the world's population will face water scarcity. Seawater desalination is considered one of the key ways to alleviate water shortages in coastal areas, but its processing capacity is still insufficient to meet the growing demand. While current mainstream seawater desalination technologies (such as reverse osmosis) are relatively mature, they still suffer from high energy consumption, high costs, and membrane fouling, limiting their widespread application in underdeveloped and remote areas.

[0003] Against this backdrop, solar-driven interfacial evaporation technology, with its near-zero energy consumption, environmental friendliness, and flexible deployment, has become a promising alternative. However, the practical application of this technology is still limited by the evaporation rate and energy utilization efficiency. Therefore, developing novel evaporators that combine efficient photothermal conversion with rapid water transport capabilities has become a key research focus. Summary of the Invention

[0004] Purpose of the invention: To address the problems of low evaporation rate and insufficient photothermal conversion efficiency in existing solar water evaporation technologies, this invention designs a silane-modified graphene oxide / polyvinyl alcohol composite aerogel evaporator, its preparation method, and its application.

[0005] Technical solution: A method for preparing a silane-modified graphene oxide / polyvinyl alcohol (GO / SPH) composite aerogel evaporator, comprising the following steps:

[0006] Step 1: Prepare the co-solvent system: Dissolve polyvinyl alcohol completely in deionized water, cool, add anhydrous ethanol, and stir to form a homogeneous polyvinyl alcohol / ethanol-water co-solvent system.

[0007] Step 2, Dispersion and Functionalization: Add graphene oxide powder to the co-solvent system obtained in Step 1 and disperse it by ultrasound. Then add (3-aminopropyl)trimethoxysilane and continue to sonicate it to achieve uniform dispersion.

[0008] Step 3, Crosslinking and Gelification: Glutaraldehyde is added to the mixture from Step 2 as a crosslinking agent, stirred and allowed to stand to complete the crosslinking and gelation process, resulting in silane-modified graphene oxide / polyvinyl alcohol (GO / SPH) hydrogel.

[0009] Step 4, Purification and Drying: The silane-modified graphene oxide / polyvinyl alcohol (GO / SPH) hydrogel obtained in Step 3 is repeatedly soaked and washed to remove impurities, and finally freeze-dried to obtain the GO / SPH composite aerogel evaporator.

[0010] Furthermore, the specific steps of step one are as follows:

[0011] Dissolve polyvinyl alcohol in deionized water at a concentration of 2-5 wt%, and stir at 80-95 °C and 500 rpm / s until completely dissolved; after cooling to room temperature, add anhydrous ethanol, wherein the mass ratio of ethanol to deionized water is 1:(3.5-4.5), and stir at 50-150 rpm / s until homogeneous.

[0012] Furthermore, in step two:

[0013] The mass ratio of the graphene oxide powder to the polyvinyl alcohol / ethanol-water cosolvent system is (0.1-0.5):10;

[0014] The ratio of the amount of (3-aminopropyl)trimethoxysilane added to the amount of polyvinyl alcohol / ethanol-water cosolvent system is (0.3~0.7) mL:10g.

[0015] The ultrasonic dispersion time after adding graphene oxide powder is 5-15 minutes; the ultrasonic treatment time after adding (3-aminopropyl)trimethoxysilane is 3-8 minutes.

[0016] Furthermore, in step three:

[0017] The ratio of glutaraldehyde to polyvinyl alcohol / ethanol-water co-solvent system is 420uL:10g.

[0018] The stirring time after adding glutaraldehyde is 0.5 to 2 minutes; the mixture is allowed to stand at room temperature for 0.5 to 2 hours; the laboratory temperature is 20 to 25 ℃.

[0019] Furthermore, step four involves the following specific steps:

[0020] The silane-modified graphene oxide / polyvinyl alcohol hydrogel obtained in step 3 was immersed in ultrapure water for 10-20 minutes, and repeated 3-6 times; then, it was pre-frozen at -50 °C and then freeze-dried under vacuum of less than 10 Pa for 20-30 hours.

[0021] The GO / SPH composite aerogel evaporator prepared by this invention has a three-dimensional porous framework formed by cross-linking polyvinyl alcohol with (3-aminopropyl)trimethoxysilane and glutaraldehyde. Graphene oxide nanosheets are uniformly dispersed and embedded in the framework, and amino functional groups derived from (3-aminopropyl)trimethoxysilane are covalently bonded to the cross-linking network, which together constitute the GO / SPH composite aerogel evaporator.

[0022] The evaporator prepared by this invention has a high evaporation rate, high photothermal conversion efficiency, and good wastewater treatment effect. Furthermore, it has a simultaneous deep water purification function during evaporation. It can be used for solar water evaporation and deep purification of water contaminated with heavy metals.

[0023] Beneficial effects:

[0024] (1) In the preparation method of the present invention, polyvinyl alcohol is first completely dissolved in deionized water, and after cooling, anhydrous ethanol is added to form a homogeneous co-solvent system; then, graphene oxide powder is dispersed in the system, and (3-aminopropyl)trimethoxysilane and glutaraldehyde are introduced sequentially, and cross-linking and gelation are completed after standing to obtain a hydrogel; finally, the hydrogel is purified by repeated soaking and washing, and after freeze-drying, the final silane-modified graphene oxide / polyvinyl alcohol hybrid evaporator, namely GO / SPH composite aerogel evaporator (Graphene oxide, Siloxane, PVA, Hydrogel). This method can systematically optimize the structure and performance of the evaporator by controlling the amount of graphene oxide added.

[0025] (2) The silane-modified graphene oxide / polyvinyl alcohol composite aerogel evaporator prepared in this invention, namely the GO / SPH composite aerogel evaporator. This evaporator undergoes a self-catalytic crosslinking reaction between (3-aminopropyl)trimethoxysilane and the polyvinyl alcohol framework at room temperature. The evaporator uses crosslinked PVA as the framework to construct a hydrophilic three-dimensional interconnected porous framework. On the one hand, this structure serves as an efficient water transport channel, ensuring continuous water supply; on the other hand, its porous characteristics significantly improve the solar light capture efficiency through multiple internal light scattering, while its inherent low thermal conductivity effectively localizes heat at the evaporation interface, minimizing heat loss. In this structure, graphene oxide serves as an efficient photothermal center, converting absorbed solar energy into thermal energy; while the amino functional groups covalently anchored in the network serve as specific adsorption sites, deeply removing heavy metal ions from the water through chelation. This integrated design of "water supply-photothermal-adsorption" ultimately enables the GO / SPH composite aerogel evaporator to simultaneously possess high evaporation rate, high photothermal conversion efficiency, and excellent water purification capabilities. Attached Figure Description

[0026] Figure 1The macroscopic and microscopic morphology characterization results are for the 3wt% GO / SPH composite evaporator prepared in Example 1 and the SPH evaporator prepared in Example 2 of this invention.

[0027] Figure 2 The image shows a comparison of the Fourier transform infrared (FTIR) spectra of the 3 wt% GO / SPH aerogel evaporator prepared in Example 1 with its precursors PVA and APTMS.

[0028] Figure 3 The image shows a time-series image of the dynamic water contact angle of the evaporator surface prepared in Example 1, which is a superhydrophilic property.

[0029] Figure 4 Comparison of UV-Vis-NIR absorption spectra of the evaporators (dry and wet states) prepared in Examples 1-4 of this invention.

[0030] Figure 5 A comparison of the pure water evaporation rates of GO / SPH evaporators with different graphene oxide contents under one day of sunlight irradiation.

[0031] Figure 6 The desalination performance and operational stability characterization results of the GO / SPH evaporator prepared in Example 1 are shown.

[0032] Figure 7 The image shows the results of a 3-day outdoor experiment on the GO / SPH composite hydrogel evaporator prepared in Example 1 of this invention.

[0033] Figure 8 The results show the characterization of the simultaneous removal performance of multiple pollutants by the GO / SPH composite hydrogel evaporator prepared in Example 1 of this invention.

[0034] Figure 9 This is a comparison chart of dye concentrations before and after purification of simulated wastewater containing various organic dyes (methyl orange, methylene blue, and rhodamine B).

[0035] Figure 10 The adsorption performance of the GO / SPH composite hydrogel evaporator prepared in Embodiment 1 of this invention for heavy metal pollutants is characterized. Detailed Implementation

[0036] The technical solution of the present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0037] It should be noted that the one or more steps described in this invention do not exclude the possibility of other methods or steps before or after the combined steps, nor do they exclude the possibility of inserting other methods or steps between the explicitly mentioned steps. Furthermore, these embodiments are only used to illustrate the technical solutions of this invention and are not intended to limit the scope of this invention. Unless otherwise stated, the numbering of the method steps is only used to distinguish each step and is not intended to limit their execution order or the scope of implementation of this invention. Adjustments or rearrangements of the relative relationships of the steps, without changing the essential technical content, still fall within the scope of implementation of this invention. The raw materials and instruments used in the embodiments are not particularly limited and can be purchased commercially or prepared according to conventional methods skilled in the art.

[0038] Example 1

[0039] A method for preparing an evaporator GO / SPH includes the following steps:

[0040] (1) Preparation of ethanol-PVA co-solution system:

[0041] Preparation of polyvinyl alcohol mother liquor: 2 g of polyvinyl alcohol was completely dissolved in 63 g of water (63 mL) (the solubility of polyvinyl alcohol is 32 mg / mL). The above solution was placed in a heated magnetic stirrer at a temperature of 90 °C and a speed of 500 rpm / s. In order to completely dissolve polyvinyl alcohol in water, the stirring was carried out at a temperature of 90 °C until the particles at the bottom of the beaker were completely dissolved, resulting in a homogeneous and transparent aqueous solution of polyvinyl alcohol.

[0042] Construction of the co-solvent system: After the transparent polyvinyl alcohol aqueous solution was cooled to room temperature, 18 g of ethanol was added at 100 rpm / s. When the solution became clear and transparent, a homogeneous PVA / ethanol-water co-solvent system was obtained.

[0043] (2) Preparation steps of GO / SPH composite evaporator:

[0044] Industrial monolayer graphene oxide was ground to obtain graphene oxide powder (GO); 10g of PVA / ethanol-water cosolvent system was taken, and 0.3g of graphene oxide powder (GO) was added to the system at room temperature. The mixture was then ultrasonically treated for 10 minutes to achieve uniform dispersion, resulting in a suspension of graphene oxide.

[0045] The suspension was continuously stirred, and 0.5 mL of (3-aminopropyl)trimethoxysilane (APTMS) was added dropwise. The suspension was then sonicated at 100 rpm for 5 minutes to ensure uniform dispersion.

[0046] Then, 420 μL of glutaraldehyde (GA) was added, and the mixture was magnetically stirred for 1 minute and then left to stand at room temperature for 1 hour to complete the crosslinking and gelation process, resulting in GO / SPH hydrogel.

[0047] The GO / SPH hydrogel was soaked in 500 mL of ultrapure water for 15 minutes, and the water was changed 3 times to remove impurities (unreacted reagents and residual ethanol). Finally, the purified hydrogel was freeze-dried for 24 hours to obtain a 3 wt% GO / SPH composite aerogel evaporator.

[0048] The freeze-drying conditions are as follows: after pre-freezing at -50 °C, freeze-drying is carried out under a vacuum of 10 Pa.

[0049] Example 2

[0050] A method for preparing an evaporator SPH includes the following steps:

[0051] (1) Preparation of ethanol-PVA co-solution system:

[0052] Preparation of polyvinyl alcohol mother liquor: 2 g of polyvinyl alcohol was completely dissolved in 63 g of water (63 mL) (the solubility of polyvinyl alcohol is 32 mg / mL). The above solution was placed in a heated magnetic stirrer at a temperature of 90 °C and a speed of 500 rpm / s. In order to completely dissolve polyvinyl alcohol in water, the stirring was carried out at a temperature of 90 °C until the particles at the bottom of the beaker were completely dissolved, resulting in a homogeneous and transparent aqueous solution of polyvinyl alcohol.

[0053] Construction of the co-solvent system: After the transparent polyvinyl alcohol aqueous solution was cooled to room temperature, 18 g of ethanol was added at 100 rpm / s. When the solution became clear and transparent, a homogeneous PVA / ethanol-water co-solvent system was obtained.

[0054] (2) Preparation steps of GO / SPH composite evaporator:

[0055] Take 10g of PVA / ethanol-water cosolvent system, add 0.5 mL of (3-aminopropyl)trimethoxysilane, sonicate for 5 minutes to achieve uniform dispersion, then add 420 μL of glutaraldehyde, magnetically stir for 1 minute, and let stand for 1 hour to complete gelation; immerse in 500 mL of deionized water, changing the water 3 times, and freeze-dry to obtain the evaporator. Immerse the obtained gel in ultrapure water for 15 minutes, repeating five times to remove impurities, and finally freeze-dry for 24 hours to obtain the SPH evaporator.

[0056] Example 3

[0057] A method for preparing an evaporator GO / SPH includes the following steps:

[0058] (1) Preparation of ethanol-PVA co-solution system:

[0059] Preparation of polyvinyl alcohol mother liquor: 2 g of polyvinyl alcohol was completely dissolved in 63 g of water (63 mL) (the solubility of polyvinyl alcohol is 32 mg / mL). The above solution was placed in a heated magnetic stirrer at a temperature of 90 °C and a speed of 500 rpm / s. In order to completely dissolve polyvinyl alcohol in water, the stirring was carried out at a temperature of 90 °C until the particles at the bottom of the beaker were completely dissolved, resulting in a homogeneous and transparent aqueous solution of polyvinyl alcohol.

[0060] Construction of the co-solvent system: After the transparent polyvinyl alcohol aqueous solution was cooled to room temperature, 18 g of ethanol was added at 100 rpm / s. When the solution became clear and transparent, a homogeneous PVA / ethanol-water co-solvent system was obtained.

[0061] (2) Preparation steps of GO / SPH composite evaporator:

[0062] Take 10g of PVA / ethanol-water cosolvent system, add 0.1g of graphene oxide powder and 0.5ml of (3-aminopropyl)trimethoxysilane sequentially, and sonicate for 10 minutes and 5 minutes respectively to achieve uniform dispersion. Then add 420µL of glutaraldehyde, stir magnetically for 1 minute, and let stand for 1 hour to complete gelation. Soak in 500mL of deionized water, changing the water 3 times, and freeze-dry to obtain the evaporator. Soak the obtained gel in ultrapure water for 15 minutes, repeating five times to remove impurities. Finally, freeze-dry for 24 hours to obtain a 1wt% GO / SPH composite aerogel evaporator.

[0063] Example 4

[0064] A method for preparing an evaporator GO / SPH includes the following steps:

[0065] (1) Preparation of ethanol-PVA co-solution system:

[0066] Preparation of polyvinyl alcohol mother liquor: 2 g of polyvinyl alcohol was completely dissolved in 63 g of water (63 mL) (the solubility of polyvinyl alcohol is 32 mg / mL). The above solution was placed in a heated magnetic stirrer at a temperature of 90 °C and a speed of 500 rpm / s. In order to completely dissolve polyvinyl alcohol in water, the stirring was carried out at a temperature of 90 °C until the particles at the bottom of the beaker were completely dissolved, resulting in a homogeneous and transparent aqueous solution of polyvinyl alcohol.

[0067] Construction of the co-solvent system: After the transparent polyvinyl alcohol aqueous solution was cooled to room temperature, 18 g of ethanol was added at 100 rpm / s. When the solution became clear and transparent, a homogeneous PVA / ethanol-water co-solvent system was obtained.

[0068] (2) Preparation steps of GO / SPH composite evaporator:

[0069] Take 10g of PVA / ethanol-water cosolvent system, add 0.5g of graphene oxide powder and 0.5ml of (3-aminopropyl)trimethoxysilane sequentially, and sonicate for 10 minutes and 5 minutes respectively to achieve uniform dispersion. Then add 420µL of glutaraldehyde, stir magnetically for 1 minute, and let stand for 1 hour to complete gelation. Soak in 500mL of deionized water, changing the water 3 times, and freeze-dry to obtain the evaporator. Soak the obtained gel in ultrapure water for 15 minutes, repeating five times to remove impurities. Finally, freeze-dry for 24 hours to obtain a 5wt% GO / SPH composite aerogel evaporator.

[0070] Test Example 1

[0071] (1) Characterization results of the evaporators prepared in Examples 1 to 4:

[0072] Figure 1 The macroscopic and microscopic morphology characterization results of the 3wt% GO / SPH composite aerogel evaporator prepared in Example 1 and the pure SPH evaporator prepared in Example 2 are shown in Figure d. Among them, a is a macroscopic photograph of the freeze-dried 3wt% GO / SPH composite aerogel evaporator in Example 1, b is a scanning electron microscope (SEM) image of the pure SPH scaffold (SPH evaporator) without GO prepared in Example 2, c is a scanning electron microscope (SEM) image of graphene oxide (GO), and d is a SEM image of the 3wt% GO / SPH composite aerogel evaporator prepared in Example 2. These figures demonstrate the composite situation of GO nanosheets in the porous hydrogel matrix. As can be seen from Figure d, GO nanosheets were successfully composited into the porous hydrogel matrix.

[0073] Figure 2 The image shows a comparison of the Fourier transform infrared (FTIR) spectra of the 3 wt% GO / SPH composite aerogel evaporator prepared in Example 1 with its precursors PVA and APTMS (results of chemical composition and surface hydrophilicity characterization). Figure 2 The appearance of characteristic peaks in PVA and APTMS proves the successful crosslinking of PVA and APTMS.

[0074] Figure 3 This is a time-series image of the dynamic water contact angle of the superhydrophilic evaporator surface prepared in Example 1. Figure 3 The image shows a dynamic water contact angle time series (complete wetting within 0.6 seconds) demonstrating the surface's superhydrophilic properties. The image confirms the successful cross-linking of the Si-O-Si covalent network and the presence of amino (–NH2) functional groups.

[0075] Figure 4Comparison of UV-Vis-NIR absorption spectra of the evaporators (dry and wet states) prepared in Examples 1-4 of this invention: UV-Vis-NIR absorption spectra of GO / SPH composite aerogel evaporator, pure SPH evaporator and cured (3-aminopropyl)trimethoxysilane. It can be seen from the figure that the introduction of GO significantly improves UV absorption.

[0076] (2) Pure water evaporation rate test:

[0077] GO / SPH composite aerogel evaporators and SPH evaporators were used for solar water evaporation, respectively. Simulated sunlight was achieved using a xenon lamp equipped with an AM 1.5 filter, with a light intensity of 100 mW / cm². -2 The experimental environment was controlled at 60% humidity and 25℃. An infrared camera was used to monitor the temperature change of the top evaporation surface. The evaporation rate was calculated by measuring the total mass change using a balance (accurate to 0.1 mg), and the obtained evaporation rate was 2.21 kg m³. -2 h -1 (like Figure 5 (As shown).

[0078] (3) Seawater desalination test:

[0079] The GO / SPH composite hydrogel evaporator prepared in Example 1 was used for solar desalination. Simulated seawater (NaCl, 2.74 wt%, MgSO4, 0.65 wt%, KCl, 0.076 wt%, CaCl2, 0.1136 wt%) was prepared. The evaporator was placed in a transparent, sealed quartz collector, and the desalination was carried out at 100 mW / cm². -2 Under light intensity irradiation, the evaporated liquid was collected separately, and the ion concentration change was measured by inductively coupled plasma atomic emission spectrometry (ICP) to obtain the removal rate (e.g., Figure 6 shown in a), Na + Mg 2+ , K + , and Ca 2+ The ion concentrations decreased from 10780 ppm, 1298 ppm, 400 ppm, and 410 ppm to 0.55 ppm, 0.11 ppm, 0.31 ppm, and 0.15 ppm, respectively, with removal rates of 99.99%, 99.97%, 99.92%, and 99.96%, all meeting the World Health Organization (WHO) drinking water standards.

[0080] Figure 6 The results represent the desalination performance and operational stability characterization of the GO / SPH evaporator prepared in Example 1 of this invention; where a represents the four main ions (Na+, Na+, and Sodium) in simulated seawater before and after purification by the GO / SPH evaporator. + Mg2+ , K + Ca 2+ The graphs show the concentration comparison of the GO / SPH evaporator, b, the evaporation rate variation of the GO / SPH evaporator under intermittent light (12 hours light / 12 hours dark) for five consecutive cycles, c, the average evaporation rate during the light and dark periods of the above five cycles, and d, the evaporation performance of the GO / SPH evaporator in brine with different salinity. The graphs confirm that the evaporator has high desalination capacity and good cyclic operation stability.

[0081] The effect of different salt concentrations on the desalination performance of GO / SPH evaporators is as follows: Figure 6 As shown in Figure d, the GO / SPH evaporator has evaporation rates of 2.15 kg / m³ for 3.5%, 5%, 7%, and 10% brine, respectively. -2 h -1 2.12 kg m -2 h -1 2.06 kg m -2 h -1 2.02 kg m -2 h -1 .

[0082] Figure 5 The figures show the characterization results of the photothermal and solar evaporation performance of the evaporators prepared in Examples 1-4 of this invention; evaporation rate graphs for the GO / SPH composite aerogel evaporator, pure SPH, and pure water after 1 hour of evaporation. As can be seen from the figures, the introduction of GO significantly improves light absorption and ultimately achieves high evaporation rate and high photothermal conversion efficiency.

[0083] To test the durability of the GO / SPH composite hydrogel evaporator, a five-day indoor seawater circulation experiment was conducted at 100 mW / cm². -2 After 8 hours of continuous light irradiation and a five-day cyclical experiment, the hourly water evaporation and the total daily water evaporation over 8 hours did not fluctuate significantly (e.g., Figure 6 As shown in Figures b and c), the GO / SPH evaporator demonstrates excellent durability.

[0084] To test the practical performance of the GO / SPH composite hydrogel evaporator, a three-day outdoor experiment was conducted. The GO / SPH evaporator demonstrated a better evaporation rate than in a closed indoor environment, reaching a maximum of 3.57 kg m³. -2 h -1 (like Figure 7 (As shown).

[0085] Figure 7The results of a 3-day outdoor experiment on the GO / SPH composite hydrogel evaporator prepared in Example 1 of this invention are shown in the figure: the comparison of evaporation rate, outdoor light, wind speed and temperature at corresponding time periods. The figure can prove that the GO / SPH composite hydrogel evaporator can achieve stable evaporation outdoors. Figure 7 (ac) represents the evaporation rate of simulated seawater and the corresponding outdoor light intensity at different times during the three-day outdoor experiment, while (df) represents the wind speed and outdoor temperature at different times during the three-day outdoor experiment.

[0086] (4) Heavy metal wastewater treatment test:

[0087] Figure 8 The results show the characterization of the simultaneous removal performance of multiple pollutants by the GO / SPH composite hydrogel evaporator prepared in Example 1 of this invention; the schematic diagram shows the experimental setup for simultaneous solar evaporation and heavy metal ion removal, including the removal of multiple heavy metal ions (Cu). 2+ , Cr 3+ Cd 2+ , Pb 2+ A comparison chart of ion concentrations before and after simulated wastewater purification.

[0088] The GO / SPH hydrogel evaporator was used for solar-powered wastewater treatment, specifically for wastewater containing 10 ppm Cu. 2+ Cr 3+ Pb 2+ Cd 2+ Wastewater is treated by placing the evaporator in a transparent, sealed quartz collector at a temperature of 100 mW / cm². -2 Under light intensity irradiation, the evaporated liquid was collected separately, and the ion concentration change was measured by inductively coupled plasma atomic emission spectrometry (ICP) to obtain the removal rate (e.g., Figure 8 As shown, almost no heavy metal ions were detected in the evaporated distillate (represented by NA in the figure). The GO / SPH evaporator is suitable for Cu... 2+ Cr 3+ Pb 2+ Cd 2+ The removal rate is greater than 99.99%, and the Cu in the evaporating liquid... 2+ Cr 3+ Pb 2+ Cd 2+ The concentrations of the ions were 0.021 ppb, 0.016 ppb, 0.043 ppb, and 0.026 ppb, respectively, all of which met the World Health Organization (WHO) drinking water standards.

[0089] (5) Organic pollutant liquid treatment test:

[0090] Figure 9This is a comparison chart of dye concentrations before and after purification of simulated wastewater containing various organic dyes (methyl orange, methylene blue, and rhodamine B). Figure 9 (c) shows the simulated wastewater containing multiple organic dyes (methyl orange, methylene blue, and rhodamine B) before and after solar purification treatment, while (d) shows a comparison of dye concentrations. The figures demonstrate that the GO / SPH evaporator not only efficiently produces water but also possesses the ability to deeply purify complex polluted water bodies.

[0091] The GO / SPH composite hydrogel evaporator prepared in Example 1 was used for solar-powered wastewater treatment, treating methylene blue, rhodamine B, and methyl orange dyes at 10 ppm. The evaporator was placed in a transparent, sealed quartz collector and treated with 100 mW cm⁻¹. -2 Under light intensity irradiation, the evaporated liquids were collected separately, and the dye solubility in the evaporated liquid and the original liquid was measured by high-performance liquid chromatography (HPLC). Figure 9 As shown in the figure, the removal rates were obtained. The removal rates obtained by the GO / SPH evaporator and the SPH evaporator were 99.48% for methylene blue, 99.56% for rhodamine B, and 99.87% for methyl orange.

[0092] (6) Performance test of heavy metal contaminated liquid treatment:

[0093] Figure 10 The following are the results elucidating the removal mechanism of heavy metal ions by APTMS in Example 1 of this invention; wherein, a is a schematic diagram of a model experiment elucidating the direct chelating ability of APTMS, b is a macroscopic photograph showing the immediate formation of colored precipitates after adding APTMS to solutions of different heavy metal ions, and c is a reaction between APTMS and Cu. 2+ , Cr 3+ Cd 2+ , Pb 2+ Macroscopic photographs of the dried precipitates formed after solution treatment, where d is the high-resolution XPS spectrum of the corresponding precipitate (Cu 2p, Cr 2p, Cd 3d, Pb 4f).

[0094] APTMS was added dropwise to a solution containing Cu. 2+ Cr 3+ Pb 2+ Cd 2+ Precipitation phenomena were observed in heavy metal ion solutions. The GO / SPH composite hydrogel evaporator was used for heavy metal wastewater treatment, particularly for solutions containing Cu. 2+ Cr 3+ Pb 2+ Cd 2+Wastewater containing heavy metal ions was treated by placing an evaporator in a transparent, sealed quartz collector and stirring at 100 rpm to obtain the removal rate. The GO / SPH composite hydrogel evaporator was used for Cu... 2+ Cr 3+ Pb 2+ Cd 2+ The removal rates of heavy metal ions were 99.7%, 99.6%, 99.97%, and 99.8%, respectively.

[0095] This invention first dissolves polyvinyl alcohol (PVA) in deionized water to form a homogeneous solution. After cooling, anhydrous ethanol is added to construct a PVA / ethanol-water co-solvent system. Subsequently, a specific mass of graphene oxide (GO) powder is dispersed in the co-solvent and ultrasonically treated to ensure uniform distribution. Next, (3-aminopropyl)trimethoxysilane (APTMS) is introduced to enhance the compatibility and binding force between components. Then, glutaraldehyde (GA) is added as a crosslinking agent, and the crosslinking and gelation process is completed at room temperature to form a GO / SPH hydrogel. Finally, the obtained hydrogel is repeatedly soaked and washed with ultrapure water to remove impurities, and then freeze-dried to obtain the final GO / SPH composite aerogel evaporator.

[0096] The GO / SPH evaporator prepared in this invention utilizes the excellent photothermal conversion performance of graphene oxide and the unique rapid water transport and thermal localization capabilities of PVA three-dimensional porous aerogel to achieve extremely high water evaporation rates and solar energy conversion efficiency. Simultaneously, the robust network structure constructed through chemical cross-linking ensures the mechanical strength and stability of the evaporator during long-term use. The inherent chelating amino groups can effectively react with heavy metal ions and negatively charged pollutant ions in the water through coordination and electrostatic adsorption, thereby achieving deep purification while producing water, demonstrating broad application prospects in the fields of seawater desalination and water purification.

[0097] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention.

Claims

1. A method for preparing a silane-modified graphene oxide / polyvinyl alcohol composite aerogel evaporator, characterized in that, Includes the following steps: Step 1: Prepare the co-solvent system: Dissolve polyvinyl alcohol completely in deionized water, cool, add anhydrous ethanol, and stir to form a homogeneous polyvinyl alcohol / ethanol-water co-solvent system. Step 2, Dispersion and Functionalization: Add graphene oxide powder to the co-solvent system obtained in Step 1 and disperse it by ultrasound. Then add (3-aminopropyl)trimethoxysilane and continue to sonicate it to achieve uniform dispersion. Step 3, Crosslinking and Gelification: Glutaraldehyde is added to the mixture from Step 2 as a crosslinking agent, stirred and allowed to stand to complete the crosslinking and gelation process, resulting in silane-modified graphene oxide / polyvinyl alcohol hydrogel. Step 4, Purification and Drying: The silane-modified graphene oxide / polyvinyl alcohol hydrogel obtained in Step 3 is soaked and washed, and finally freeze-dried to obtain the GO / SPH composite aerogel evaporator.

2. The preparation method according to claim 1, characterized in that, Step one involves the following steps: Polyvinyl alcohol is dissolved in deionized water at a concentration of 2-5 wt%, and stirred at 80-95 °C until completely dissolved; after cooling to room temperature, anhydrous ethanol is added and stirred until homogeneous, wherein the mass ratio of ethanol to deionized water is 1:(3.5-4.5).

3. The preparation method according to claim 1, characterized in that, In step two, the mass ratio of the graphene oxide powder to the polyvinyl alcohol / ethanol-water co-solvent system is (0.1-0.5):10; The ratio of the amount of (3-aminopropyl)trimethoxysilane added to the amount of polyvinyl alcohol / ethanol-water cosolvent system is (0.3~0.7) mL:10g.

4. The preparation method according to claim 1, characterized in that, In step three, the ratio of glutaraldehyde to the polyvinyl alcohol / ethanol-water co-solvent system is 420uL:10g.

5. The preparation method according to claim 1, characterized in that, In step two, the ultrasonic dispersion time after adding graphene oxide powder is 5-15 minutes; after adding (3-aminopropyl)trimethoxysilane, the ultrasonic treatment time is 3-8 minutes.

6. The preparation method according to claim 1, characterized in that, In step three, the stirring time after adding glutaraldehyde is 0.5 to 2 minutes; the standing operation is carried out at room temperature for 0.5 to 2 hours.

7. The preparation method according to claim 1, characterized in that, Step four involves the following steps: The silane-modified graphene oxide / polyvinyl alcohol hydrogel obtained in step 3 was immersed in ultrapure water for 10-20 minutes, and repeated 3-6 times. Then, it was pre-frozen at -50 °C and freeze-dried for 20-30 hours under a vacuum of less than 10 Pa to obtain a GO / SPH composite aerogel evaporator.

8. A silane-modified graphene oxide / polyvinyl alcohol composite aerogel evaporator prepared by any of the preparation methods described in claims 1-7.

9. The application of the silane-modified graphene oxide / polyvinyl alcohol composite aerogel evaporator according to claim 8 in seawater desalination and water purification.

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