Preparation method and application of three-dimensional porous photo-thermal material based on polyoxometallate dominated hydrophilic-hydrophobic modification

Abstract

The invention relates to a preparation method and application of a three-dimensional porous photo-thermal material based on polyoxometallate dominated hydrophilic-hydrophobic modification, polyoxometallate and aniline are dissolved in a solvent system and uniformly mixed, then the obtained solution is uniformly poured on a melamine foam substrate, after full dipping, a solvothermal reaction is performed in a reaction kettle, and the three-dimensional porous photo-thermal material is obtained. And after the reaction is finished, washing and drying to obtain the polyoxometallate dominated self-assembly modified three-dimensional porous photo-thermal material. The method has the advantages that the polyoxometallate-dominated self-assembly modified three-dimensional porous photo-thermal material, photo-thermal site construction and surface hydrophobic modification are perfectly fused, efficient coating and hydrophobic modification of the three-dimensional porous adsorbent surface photo-thermal material are achieved, and meanwhile solar steam generation and crude oil recovery are achieved.

Description

Technical Field

[0001] This invention belongs to the field of solar photothermal conversion and relates to a method for preparing a three-dimensional porous photothermal material based on polyoxometalate-dominated hydrophilic-hydrophobic modification and its application, particularly to the use of this photothermal material to drive solar photothermal seawater desalination and marine oil spill recovery. Background Technology

[0002] With global population growth and the acceleration of industrialization and urbanization, the increasing scarcity of freshwater resources has become a significant challenge to social development. Traditional seawater desalination technologies such as reverse osmosis, electrodialysis, and distillation generally suffer from high energy consumption, high operating costs, and water pollution, severely limiting their practical application.

[0003] Solar-driven desalination, utilizing renewable solar energy to drive seawater evaporation for freshwater production, holds promise as an effective solution to global water scarcity, as it directly produces freshwater with minimal carbon footprint. Currently used photothermal conversion materials (such as graphene, carbon nanotubes, gold nanoparticles, silver nanoparticles, oxide nanoparticles, and silicon nanoparticles) still face challenges due to insufficient heat transfer efficiency from active materials to water molecules. Optimizing the composition of photothermal conversion materials and the water vapor transport structure could further improve the efficiency of solar-driven desalination. However, in practical applications, solar-driven seawater desalination faces more severe environmental challenges. On one hand, seawater desalination suffers from salt accumulation, oil spills, or marine fouling, leading to blockages and corrosion. On the other hand, frequent heavy crude oil spills, including those from offshore oil fields, tanker cargo, and ship fuel, result in oil slicks on the ocean surface. When photothermal materials come into contact with oily seawater, the high viscosity of the crude oil can be adsorbed and coated onto the material's surface and internal pores.

[0004] While three-dimensional porous photothermal adsorbents can reduce crude oil viscosity and achieve crude oil absorption and seawater desalination under solar radiation, their performance is unsatisfactory due to complex preparation processes, easy shedding of photothermal components, and difficulty in modifying the overall surface to be hydrophobic. Therefore, it is of great significance to construct novel photothermal functional materials that combine high photothermal conversion efficiency, hydrophilic-hydrophobic functional sites, stable structure, and simple preparation processes to achieve dual-functional applications of solar photothermal seawater desalination and crude oil recovery. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a three-dimensional porous photothermal material based on polyoxometalate-dominant hydrophilic-hydrophobic modification and its application, so as to achieve efficient encapsulation and hydrophobic modification of the photothermal material on the surface of the three-dimensional porous adsorbent, while realizing solar steam generation and crude oil recovery.

[0006] The technical solution of this invention is: A method for preparing a three-dimensional porous photothermal material based on polyoxometalate-dominant hydrophilic-hydrophobic modification, characterized by the following steps: According to the polyoxometalate H3PMo 12 O 40 The polyoxometalate and aniline were dissolved in a solvent system at a molar volume of 0.1: (5-15) mmol / μL and mixed evenly. The resulting solution was then uniformly poured onto a melamine foam substrate and fully impregnated. The substrate was then subjected to a solvothermal reaction in a reactor. After the reaction was completed, the substrate was washed and dried to obtain a three-dimensional, porous photothermal material modified by self-assembly dominated by the polyoxometalate.

[0007] Furthermore, the reaction temperature is 140°C and the reaction time is 3 hours.

[0008] Furthermore, the molar volume of the polyoxometalate and aniline is 0.01 mmol / μL.

[0009] Furthermore, the molar volume ratio of the polyoxometalate to the solvent is 0.1:8 mmol / mL.

[0010] Furthermore, the solvent system is a mixture of oleic acid (OA) and ethanol solution.

[0011] More preferably, the volume ratio of oleic acid (OA) to ethanol solution is 1:3.

[0012] Furthermore, the solvent system is 8 mL, and the size of the melamine foam is 2 cm × 2 cm × 1 cm.

[0013] Furthermore, during washing, soak and wash three times alternately with water and anhydrous ethanol.

[0014] Application of a three-dimensional porous photothermal material based on polyoxometalate-dominated hydrophilic-hydrophobic modification prepared by the above-mentioned preparation method in solar steam generation and seawater desalination.

[0015] Application of a three-dimensional porous photothermal material based on polyoxometalate-dominated hydrophilic-hydrophobic modification prepared by the above-mentioned preparation method in the treatment of marine oil spills and seawater desalination.

[0016] The principle of this invention is as follows: Three-dimensional, porous photothermal materials modified by self-assembly of polyoxometalates perfectly integrate photothermal site construction and surface hydrophobic modification. Among them, traditional oxidants ammonium persulfate and ferric chloride can oxidize aniline into polyaniline materials with photothermal properties. However, due to the lack of strong interactions between polyaniline particles on the melamine foam skeleton surface and the poor resistance of polyaniline to photobleaching, the materials synthesized in this system suffer from problems such as easy detachment of the photothermal agent and poor stability.

[0017] In this study, polyoxometalates, possessing oxidizing capabilities and acting as anions, interact with the amino groups on the surface of melamine, initiating the oxidative polymerization of aniline in situ. Furthermore, they are reduced to heteropolyblue (HPB), which exhibits excellent photothermal conversion capabilities. The presence of heteropolyblue not only enhances the overall photothermal performance but also serves as an active site for steam production due to its hydrophilicity. In addition, its high negative charge acts as a bridge between the polyaniline and the melamine skeleton through strong electrostatic forces, maintaining the overall structure's robust mechanical properties. The hydrophobic oleic acid in the synthesis system of this invention acts as an electron acceptor, electrostatically binding to the surface regions of the cationic polymer polyaniline (i.e., regions without heteropolyblue binding), further improving the overall hydrophobic and oleophilic properties. Therefore, the MF@HPB-PAn of this invention... x -OA possesses localized hydrophilic photothermal evaporation sites and overall hydrophobicity, enabling simultaneous solar steam generation and efficient solar-powered oil spill repair.

[0018] The beneficial effects of this invention are: (1) By utilizing the self-assembly of hydrophilic heteropolyblue (HPB), polyaniline (PAn) and hydrophobic oleic acid (OA) on the surface of a three-dimensional porous melamine foam (MF) skeleton, a three-dimensional porous functional material with a localized hydrophilic-hydrophobic surface is constructed. Among them, HPB and OA molecules are affected by both electrostatic repulsion and competitive assembly, which makes the material surface exhibit hydrophilic and hydrophobic functional partitioning characteristics, thus avoiding the limitation of single hydrophilic / hydrophobic properties.

[0019] (2) The MF@HPB-PAn of the present invention 10 The capillary action generated by the 3D porous structure in the OA provides efficient water convection. The successful composite of HPB and polyaniline, two photothermal materials, enhances the overall photothermal conversion performance. Under one solar irradiation, the water evaporation rate of deionized water reaches as high as 3.60 kg·m³. -2 ·h -1 The energy efficiency reached 96.20%, and the water evaporation rate reached 3.56 kg·m³ during the evaporation of 3.5 wt% and 10 wt% seawater samples. -2 ·h -1 and 3.55 kg·m -2 ·h -1 It performed excellently in zero liquid discharge performance tests, achieving an average water evaporation rate of 3.70 kg·m³ when completely separating salt and water from high-salinity (10 wt%) seawater. -2 ·h -1 The salt harvesting efficiency is as high as 94.25%, basically achieving zero liquid discharge (ZLD).

[0020] (3) The polyoxometalate-dominated self-assembled three-dimensional, porous photothermal material of the present invention possesses excellent photothermal properties, good mechanical properties, and hydrophobic and oleophilic properties. Experimental testing revealed that the MF@HPB-PAn material of the present invention exhibits… 10 -OA achieves a crude oil recovery efficiency of up to 1.87 × 10⁻⁶. 4 kg·m -3 ·h -1 This demonstrates its enormous application potential in the field of crude oil adsorption and recovery.

[0021] In summary, the hydrophilic region of the HPB in this material promotes in-situ water evaporation, effectively enhancing its photothermal conversion performance; the hydrophobic region endows the material with strong resistance to salt fouling and surface self-cleaning capabilities; the 3D porous structure, hydrophobic surface, and excellent self-heating properties work together to significantly enhance the material's oil adsorption capacity, thereby effectively improving crude oil recovery performance. This material not only has efficient applications in seawater desalination but also provides a highly promising solution for dealing with high-viscosity crude oil spills at sea. Attached Figure Description

[0022] Figure 1 The MF@HPB-PAn prepared in Comparative Example 1 of this invention 10 Scanning electron microscope (SEM) characterization image; Figure 2 This invention relates to MF@HPB-PAn5-OA prepared in Example 1 and MF@HPB-PAn prepared in Example 2. 10 -OA and MF@HPB-PAn prepared in Example 3 15 -Scanning electron microscopy (SEM) characterization images of OA, where ab.MF@HPB-PAn5-OA and cd.MF@HPB-PAn are SEM images. 10 - SEM image of OA, ef.MF@HPB-PAn 15 - SEM image of OA; Figure 3 The MF@HPB-PAn prepared in Example 2 of this invention 10 -Scanning electron microscopy (SEM) characterization, SEM-EDX elemental mapping characterization, and Fourier transform infrared (FTIR) characterization of OA. In the figures, a. SEM image of pure MF, b. MF@HPB-PAn 10 - SEM image of OA, c.MF@HPB-PAn 10 SEM-EDX elemental mapping image of -OA, d.HPB-PAn 10 - OA infrared spectrum, e.HPB-PAn 10 -OA and HPB-PAn 10 Comparison of infrared spectra; Figure 4 HPB-PAn in Embodiment 2 of the present invention 10 -OA and HPB-PAn in Comparative Example 1 10 Transmission electron microscopy (TEM) and high-resolution TEM images of HPB-PAn 10 -High-angle annular dark field image (HAADF) characterization map and corresponding elemental mapping characterization map of OA. In the figure, a.HPB-PAn 10 TEM image, b.HPB-PAn 10 High-resolution TEM image, c.HPB-PAn 10 -TEM image of OA, d.HPB-PAn 10 -High-resolution TEM image of OA, e.HPB-PAn 10 HAADF characterization diagram and corresponding element mapping image of -OA; Figure 5 HPB-PAn in Embodiment 2 of the present invention 10 -X-ray photoelectron spectroscopy (XPS) characterization of OA; Figure 6 HPB-PAn in Embodiment 2 of the present invention 10 -X-ray diffraction (XRD) pattern of OA; Figure 7 The MF@HPB-PAn prepared in Example 2 of this invention 10 -OA, MF@HPB-PAn prepared in Comparative Example 1 10 The UV-Vis-NIR absorption spectrum of MF, the change of surface temperature over time under one solar intensity irradiation in a dry state, and MF@HPB-PAn 10 Infrared optical images at steady-state temperature of OA, water contact angle test results, and MF@HPB-PAn prepared in Example 2. 10 -The cyclic compressive stress-strain curve of OA, in the figure, a.MF@HPB-PAn 10 -OA、MF@HPB-PAn 10 b.MF@HPB-PAn UV-Vis-NIR absorption spectrum of MF 10 -OA、MF@HPB-PAn 10 MF surface temperature variation over time under dry conditions and irradiation at one solar intensity and MF@HPB-PAn 10 -Infrared optical image at steady-state temperature of OA, c.MF@HPB-PAn 10- Cyclic compressive stress-strain curves of OA, d. Water contact angle measurements on the MF surface, e. MF@HPB-PAn 10 Water contact angle measurement results on the surface, f.MF@HPB-PAn 10 -Water contact angle measurement results on OA surface, g.MF@HPB-PAn 10 -Contact angle measurement results of polydimethylsiloxane droplets on the OA surface; Figure 8 The MF@HPB-PAn prepared in Example 2 of this invention 10 - Results of solar photothermal evaporation performance test of OA, salt-water separation cycle test data, and seawater desalination performance test results. In the figure, a. Under 1 solar irradiance, MF@HPB-PAn 10 and MF@HPB-PAn 10 -The relationship between mass change and time in the water evaporation process driven by OA, b.MF@HPB-PAn 10 - OA photothermal evaporation rates and corresponding energy efficiencies in simulated deionized water (DI), seawater (salinity 3.5 wt%), and Dead Sea (salinity 10 wt%) samples, c.MF@HPB-PAn 10 -OA completed five salt-water separation cycle tests, achieving the average water evaporation rate and solute collection efficiency (NaCl simulated seawater sample: 10.0 wt%), d. MF@HPB-PAn 10 -OA completed five solute-water separation cycle tests, measuring the average water evaporation rate and solute collection efficiency (simulated industrial wastewater sample of CuSO4: 10.0 wt%), e.MF@HPB-PAn 10 -OA stability test for continuous photothermal evaporation in high-salinity brine samples for up to 120 hours, f.MF@HPB-PAn 10 - Comparison of OA with recent literature reports on photothermal evaporation performance in high-salinity systems, g. Two simulated seawater samples in MF@HPB-PAn 10 -Salinity before and after OA purification, h. Industrial wastewater samples based on MF@HPB-PAn 10 - The concentrations of four major ions / solutes in the condensate obtained after OA purification, i. dye wastewater samples based on MF@HPB-PAn 10 - The concentration of four main ions / solutes in the condensate obtained after OA purification; Figure 9 The MF@HPB-PAn prepared in Example 2 of this invention 10-OA is used in the industrial sector to recover oily substances and organic solvents, as well as to treat grease-containing wastewater from kitchens. In the figure, a. polydimethylsiloxane, b. cyclohexane, c. chloroform, d. kitchen grease; Figure 10 This refers to the MF@HPB-PAn prepared in Example 2 of the present invention. 10 -Dynamic oil adsorption behavior and crude oil recovery data of OA. In the figure, a. Temperature-viscosity curve of crude oil, b. Viscous crude oil (10 µL) at different temperatures in MF@HPB-PAn 10 - Oil absorption behavior on the top surface of OA, c. Simulated oil spill remediation system, d. MF, MF@HPB-PAn 10 -OA and frustum structure MF@HPB-PAn 10 -Real-time monitoring data curve of crude oil recovery within 20 minutes by OA, e.MF (Model I), MF@HPB-PAn 10 -OA (Model II) and MF@HPB-PAn of the frustum structure 10 - Digital image results of crude oil recovery in OA (Model III) within 20 min, f. Recovery oil mass-time curve obtained by remote control device in three solar light source on / off cycles; Detailed Implementation

[0023] The present invention will be further illustrated below with reference to the embodiments.

[0024] Example 1 First, the oxidant polyoxometalate (POM)H3PMo 12 O 40 0.1 mmol of oleic acid and 5 μL of aniline were dissolved in 8 mL of a mixed solvent system of oleic acid and ethanol (2 mL of oleic acid and 6 mL of ethanol). The mixture was sonicated to ensure homogeneity. The resulting solution was then uniformly poured onto a pre-cut melamine foam (MF: 2×2×1 cm, 2 pieces) substrate. After thorough impregnation, the mixture was reacted at 140 °C for 3 h in a reactor. After the reaction was completed, the mixture was cooled to room temperature and washed three times with alternating soaking and washing with water and anhydrous ethanol. The mixture was then dried to obtain a three-dimensional, porous photothermal material MF@HPB-PAn5-OA, which is modified by self-assembly dominated by polyoxometalates.

[0025] Example 2 First, the oxidizing agent polyoxometalate (POM) H3PMo 12 O 400.1 mmol of oleic acid and 10 μL of aniline were dissolved in 8 mL of a mixed solvent system of oleic acid and ethanol (2 mL of oleic acid and 6 mL of ethanol). The mixture was sonicated to ensure homogeneity. The resulting solution was then uniformly poured onto a pre-cut melamine foam (MF: 2 × 2 × 1 cm, 2 pieces) substrate. After thorough impregnation, the mixture was reacted at 140 °C for 3 h in a reaction vessel. After the reaction was completed, the mixture was cooled to room temperature and washed three times alternately with water and anhydrous ethanol. After drying, a three-dimensional, porous photothermal material MF@HPB-PAn, modified by self-assembly dominated by polyoxometalates, was obtained. 10 -OA.

[0026] Example 3 First, the oxidizing agent polyoxometalate (POM) H3PMo 12 O 40 0.1 mmol of oleic acid and 15 μL of aniline were dissolved in 8 mL of a mixed solvent system of oleic acid and ethanol (2 mL of oleic acid and 6 mL of ethanol). The mixture was sonicated to ensure homogeneity. The resulting solution was then uniformly poured onto a pre-cut melamine foam (MF: 2 × 2 × 1 cm, 2 pieces) substrate. After thorough impregnation, the mixture was reacted at 140 °C for 3 h in a reaction vessel. After the reaction was completed, the mixture was cooled to room temperature and washed three times alternately with water and anhydrous ethanol. After drying, a three-dimensional, porous photothermal material MF@HPB-PAn, modified by polyoxometalate-dominated self-assembly, was obtained. 15 -OA.

[0027] Comparative Example 1 First, the oxidizing agent polyoxometalate (POM) H3PMo 12 O 40 (0.1 mmol) and aniline (10 μL) were dissolved in 8 mL of ethanol solution and sonicated to mix thoroughly. The resulting solution was then uniformly poured onto a pre-cut melamine foam (MF: 2×2×1 cm, 2 pieces) substrate. After thorough impregnation, the substrate was reacted in a reactor at 140℃ for 3 h. After the reaction was completed, the substrate was cooled to room temperature and washed three times alternately with water and anhydrous ethanol. After drying, black MF@HPB-PAn was obtained. 10 Despite MF@HPB-PAn 10 It was successfully prepared, but HPB-PAn 10 It is easy to fall off.

[0028] Comparative Example 2 The polyoxometalate (POM) H3PMo from Example 2 12 O 40 Using APS (ammonium persulfate) as a substitute, and otherwise the same as in Example 2, only a small amount of polyaniline adheres to the melamine foam (MF), and it is impossible to form a composite structure modified with a deep black self-assembled coating.

[0029] Comparative Example 3 The polyoxometalate (POM) H3PMo from Example 2 12 O 40 Using ferric chloride (FC) as a substitute, and otherwise the same as in Example 2, only a small amount of polyaniline adheres to the melamine foam (MF), making it impossible to form a deep black self-assembled coating-modified composite structure.

[0030] The photothermal materials prepared in Examples 1 and 2 of this invention, and the MF@HPB-PAn prepared in Example 2 10 -Performance testing of OA photothermal materials: 1. Observation of MF@HPB-PAn using scanning electron microscopy (SEM) 10 Surface morphology, from Figure 1 In a and b, it can be clearly observed that in MF@HPB-PAn 10 The presence of numerous granular and blocky self-assembled structures on the surface indicates that a good covering coating has not been formed.

[0031] 2. Observation of MF@HPB-PAn5-OA and MF@HPB-PAn by scanning electron microscopy (SEM) 10 -OA and MF@HPB-PAn 15 -OA morphological structure, from Figure 2 As shown in a and b, the initial modification of MF@HPB-PAn5-OA was successful, but the coating thickness was low and the degree of polymerization was insufficient. From... Figure 2 From c and d, we can see that MF@HPB-PAn 10 -OA coating has moderate thickness, suitable polymerization degree, regular morphology, and no obvious defects. From Figure 2 From e and f, we can see that MF@HPB-PAn 15 The presence of numerous imperfectly assembled self-assemblies on the surface of the OA skeleton indicates an excess of polymer.

[0032] 3. Observation of MF@HPB-PAn using scanning electron microscopy (SEM) 10 -The surface morphology and composition of OA, from Figure 3 As can be seen from a, the original MF exhibits a three-dimensional interpenetrating porous structure, and its framework surface is clean and smooth. From Figure 3 As can be seen from b, HPB, PAn, and OA have successfully self-assembled and coated onto the MF surface. From Figure 3 As can be seen from c, C, N, O, Mo, and P elements are uniformly distributed in MF@HPB-PAn 10 -The overall structure of OA confirms HPB-PAn 10-Integrity of the OA coating. The composition of the self-assembled structure was analyzed using Fourier transform infrared spectroscopy (FTIR). Figure 3 As seen in d and e, HPB, PAn, and OA are all present in the system, 1053.7 cm⁻¹. -1 954.3 cm -1 869.5 cm -1 and 770.8 cm -1 The absorption peak at 1530 cm⁻¹ confirmed the presence of HPB. -1 1147 cm -1 and 1059.2-779.4 cm -1 The absorption peak at 1700.2 cm⁻¹ confirms the presence of PAn. -1 2970.7 cm -1 and 2910.2 cm -1 The absorption peak at that location confirmed the presence of OA.

[0033] 4. Observation of HPB-PAn using transmission electron microscopy (TEM) 10 and HPB-PAn 10 The composition of -OA, as shown in Figure 4a, is that without oleic acid, HPB-PAn 10 It has a nanosheet structure with a chaotic and disordered structural arrangement. From Figure 4 As seen in b, HPB clusters exist, with a size of approximately 3–5 nm. From Figure 4 As can be seen from c, HPB-PAn 10 -OA self-assembly exhibits a structure consisting of multiple layers of HPB-PAn 10 -A smooth nanosheet structure composed of stacked OA nanosheets. From Figure 4 As can be seen from d, a single HPB molecule exists, with a size of approximately 1 nm. Figure 4 As can be seen from e, HPB-PAn 10 -OA has a layered structure, and the HPB molecules in the self-assembled assembly are uniformly dispersed.

[0034] 5. Analysis of HPB-PAn by X-ray photoelectron spectroscopy (XPS) 10 The composition and valence state of -OA, from Figure 5 It can be seen that the self-assembled HPB-PAn 10 -OA contains five elements: C, N, O, Mo, and P. The element Mo has +5 and +6 valence states, indicating the existence of HPB.

[0035] 6. The composition of the self-assembled structure was further verified by X-ray powder diffraction (XRD). Figure 6As can be seen, there is a narrow peak at 7.1° corresponding to PAn (25.5°), and a broad peak in the 19.2°–28.9° range corresponding to HPB (8.9°, 20.3°, 28.2°), which strongly proves the existence of PAn and HPB.

[0036] 7. Observation of MF@HPB-PAn by UV-Vis-NIR absorption spectroscopy. 10 -OA's ability to absorb sunlight, from Figure 7 From a, we can see MF@HPB-PAn 10 -OA exhibits excellent light-harvesting capabilities across a broad spectral range of 200–2500 nm. The performance of MF@HPB-PAn was evaluated using a solar simulator. 10 -OA's solar thermal conversion capability, from Figure 7 As can be seen from b, at 1 kW·m -2 Under simulated solar irradiation, compared to dry pure MF and MF@HPB-PAn 10 MF@HPB-PAn 10 -OA exhibits the best photothermal response. Compressive stress-strain testing clarifies the optimal photothermal response of MF@HPB-PAn. 10 -OA's mechanical stability, from Figure 7 As can be seen from c, after 10 compressive stress-strain cycles, MF@HPB-PAn 10 -OA (top of illustration) still maintains good elastic deformation reversibility, while MF@HPB-PAn without OA 10 (Bottom of illustration) After compression testing, the elastic deformation cannot be recovered, resulting in a loss of overall mechanical properties. The MF@HPB-PAn was evaluated using a water contact angle test. 10 -OA surface wettability, from Figure 7 As can be seen from d, the water contact angle of melamine foam is 0°, exhibiting significant hydrophilicity. From Figure 7 From e, we can see that MF@HPB-PAn 10 The water contact angle of the surface is approximately 105.0 ± 4. o It has a certain degree of hydrophobicity. From Figure 7 From f, we can see that MF@HPB-PAn 10 -OA exhibits a water contact angle of 130.2 ± 3°, demonstrating strong hydrophobicity. From Figure 7 From g, we can see that MF@HPB-PAn 10 -OA exhibits an oil droplet contact angle of 0°, demonstrating excellent oleophilicity.

[0037] 8. Evaluate MF@HPB-PAn through solar photothermal evaporation performance testing. 10-OA water evaporation performance, from Figure 8 As can be seen from a, under one solar irradiation, MF@HPB-PAn 10 -OA exhibits the best water evaporation performance. The MF@HPB-PAn solar photothermal evaporation performance was evaluated through tests under different salinity systems. 10 -OA performance, from Figure 8 From b, we can see that MF@HPB-PAn 10 -OA maintains high water evaporation performance in systems with varying salinity (0%wt, 3.5%wt, 10%wt), with its evaporation efficiency virtually unaffected by salinity changes, demonstrating excellent salt resistance and self-cleaning properties. The MF@HPB-PAn was evaluated through salt-water separation cycle testing. 10 -OA performance stability, from Figure 8 As can be seen from c, after five running cycles, MF@HPB-PAn 10 -OA's water evaporation performance and salt collection rate remained stable, demonstrating its efficient water evaporation characteristics and strong resistance to salt pollution. From Figure 8 As can be seen from d, the water evaporation rate of the 10 wt% copper sulfate solution system reaches 3.55 kg·m. -2 ·h -1 The solute collection efficiency reached 88.25%. Figure 8 From e, we can see that MF@HPB-PAn 10 -When the OA was subjected to a continuous 120-h photothermal evaporation stability test in a high-salinity brine (10 wt%) system, the average evaporation rate remained stable at 3.62 kg·m³. -2 ·h -1 No salt crystals were observed on the surface, confirming the presence of MF@HPB-PAn. 10 -OA has excellent resistance to salt pollution. From Figure 8 As can be seen from f, compared to recently reported high-salinity systems, MF@HPB-PAn 10 -OA boasts top-tier evaporation rates and salt collection efficiency in high-salinity environments, achieving near-zero liquid discharge (ZLD). The MF@HPB-PAn model was evaluated through purification experiments on simulated seawater, industrial wastewater, and dye wastewater. 10 -OA's solar-powered seawater purification efficiency, from Figure 8 As can be seen from g, the salinity of the collected freshwater after purification is significantly reduced by 3-4 orders of magnitude compared to the initial salinity. From Figure 8 As can be seen from h, after industrial wastewater purification, Pb 2+ Cr 3+ Cd 2+ and Mn 2+ The concentration decreased by 3-4 orders of magnitude. From Figure 8As can be seen from the data, after the dye wastewater was purified, the concentration of macromolecular dyes dropped to almost zero. This demonstrates the excellent efficiency of solar-powered seawater purification.

[0038] 9. Using dyed silicone oil, cyclohexane, chloroform, and 2mL of oil from commercially available instant noodles as oily substances, and then placing them separately in water to simulate oily substance recovery and organic wastewater treatment performance tests, the performance of MF@HPB-PAn was further evaluated. 10 -OA exhibits excellent oil adsorption properties and wide applicability. Under simple direct adsorption treatment, from... Figure 9 From a, we can see that MF@HPB-PAn 10 -OA can quickly absorb and remove the dyeing silicone oil from the water surface. From Figure 9 As seen in b, for cyclohexane identified by the staining agent, MF@HPB-PAn 10 -OA can also be removed directly and easily. From Figure 9 As can be seen from 'c', MF@HPB-PAn 10 -OA can efficiently lock and completely adsorb chloroform from the seabed. Figure 9 As can be seen from d, MF@HPB-PAn 10 -OA also has excellent adsorption properties for kitchen grease.

[0039] 10. Evaluate MF@HPB-PAn through dynamic oil adsorption testing. 10 -OA's crude oil adsorption capacity, from Figure 10 As can be seen from a, the viscosity of crude oil decreases with increasing temperature (15-100℃). From Figure 10 From b, we can see that MF@HPB-PAn 10 -OA's excellent photothermal conversion performance can significantly accelerate the crude oil adsorption process. The MF@HPB-PAn was evaluated through a continuous oil recovery experiment using solar-powered pumping. 10 -OA's solar thermal crude oil recovery capacity, from Figure 10 As shown in section c, the simulated oil spill remediation system consists of a marine oil spill simulation device, photothermal adsorption materials, a solar simulator, a peristaltic pump, and an oil collection device. From Figure 10 From d and e, we can see that MF@HPB-PAn 10 -OA's photothermal self-heating properties can significantly improve crude oil adsorption and recovery capabilities, achieving a crude oil recovery efficiency of 1.87×10⁻⁶. 4 kg·m -3 ·h -1 MF@HPB-PAn with frustum structure 10 - The adsorption and recovery performance of OA crude oil has been significantly enhanced, with a crude oil recovery efficiency of up to 3.11 × 10⁻⁶. 4 kg·m -3 ·h -1 .from Figure 10 As can be seen from f, the oil recovery rate decreased significantly after the light simulator was turned off. The MF@HPB-PAn test was performed over three cycles. 10 -OA recovery efficiency remains stable, demonstrating excellent long-term stability.

[0040] In summary, this work utilizes multifunctional phosphomolybdic acid to initiate the in-situ oxidative polymerization self-assembly of aniline on the surface of a three-dimensional porous melamine foam framework, thereby constructing a 3D MF@HPB-PAn with a locally hydrophilic and globally hydrophobic surface. x -OA. This unique structure enables highly efficient seawater desalination and demonstrates excellent potential for handling marine oil spills. This work not only promotes and expands the further development of solar thermal technology but also provides new ideas for the application of polyoxometalate-based solar thermal materials.

[0041] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the embodiments. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a three-dimensional porous photothermal material based on polyoxometalate-dominated hydrophilic-hydrophobic modification, characterized in that: Includes the following steps: According to the polyoxometalate H3PMo 12 O 40 The polyoxometalate and aniline were dissolved in a solvent system at a molar volume of 0.1: (5-15) mmol / μL and mixed evenly. The resulting solution was then uniformly poured onto a melamine foam substrate and fully impregnated. The substrate was then subjected to a solvothermal reaction in a reactor. After the reaction was completed, the substrate was washed and dried to obtain a three-dimensional, porous photothermal material modified by self-assembly dominated by the polyoxometalate.

2. The method for preparing three-dimensional porous photothermal materials based on polyoxometalate-dominated hydrophilic-hydrophobic modification according to claim 1, characterized in that: The reaction temperature was 140℃ and the reaction time was 3 hours.

3. The method for preparing three-dimensional porous photothermal materials based on polyoxometalate-dominated hydrophilic-hydrophobic modification according to claim 1, characterized in that: The molar volume of the polyoxometalate and aniline is 0.01 mmol / μL.

4. The method for preparing three-dimensional porous photothermal materials based on polyoxometalate-dominated hydrophilic-hydrophobic modification according to claim 1, characterized in that: The molar volume ratio of the polyoxometalate to the solvent is 0.1:8 mmol / mL.

5. The method for preparing three-dimensional porous photothermal materials based on polyoxometalate-dominated hydrophilic-hydrophobic modification according to claim 1, characterized in that: The solvent system is a mixture of oleic acid (OA) and ethanol solution.

6. The method for preparing three-dimensional porous photothermal materials based on polyoxometalate-dominated hydrophilic-hydrophobic modification according to claim 4, characterized in that: The volume ratio of oleic acid (OA) to ethanol solution is 1:

3.

7. The method for preparing three-dimensional porous photothermal materials based on polyoxometalate-dominated hydrophilic-hydrophobic modification according to claim 1, characterized in that: The solvent system is 8 mL, and the size of the melamine foam is 2 cm × 2 cm × 1 cm.

8. The method for preparing three-dimensional porous photothermal materials based on polyoxometalate-dominant hydrophilic-hydrophobic modification according to claim 1, characterized in that: During washing, soak and wash three times alternately with water and anhydrous ethanol.

9. The application of a three-dimensional porous photothermal material based on polyoxometalate-dominated hydrophilic-hydrophobic modification prepared by the preparation method as described in claim 1 in solar steam generation and seawater desalination.

10. The application of a three-dimensional porous photothermal material based on polyoxometalate-dominated hydrophilic-hydrophobic modification prepared by the preparation method as described in claim 1 in the treatment of marine oil spills and seawater desalination.

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