Flexible polypyrrole modified enteromorpha photothermal film as well as preparation method and application thereof

Abstract

The invention relates to a flexible polypyrrole modified enteromorpha photothermal film and a preparation method and application thereof. The modified enteromorpha photothermal film is a photothermal film material prepared by stacking uncarbonized enteromorpha as a raw material and pyrrole as a modifier layer by layer. The prepared polypyrrole / enteromorpha photo-thermal fiber membrane is small in density, good in acid and alkali resistance and thermal stability and high in hydrophilicity, has the advantages of being low in cost, high in cycle performance, good in salt resistance, free of secondary pollution and the like, and has wide application prospects in actual production.

Description

Technical Field

[0001] The present invention relates to a polypyrrole-modified enteromorpha photothermal film for solar-driven seawater desalination and preparation and application thereof, belonging to the field of chemistry and environmental technology. Background Art

[0002] Water, as the source of life, is the cornerstone of human survival. However, with the rapid population growth and economic development, the shortage of freshwater resources has become a global challenge, prompting researchers to turn their attention to the ocean, the largest reservoir on Earth. Due to its huge development potential, seawater desalination technology is generally regarded as a key breakthrough in alleviating the freshwater resource crisis. Currently, mainstream technologies include distillation, electrodialysis, ion exchange and reverse osmosis, but high energy consumption is common in actual applications, which not only increases treatment costs but also poses the risk of causing secondary environmental pollution. These bottlenecks seriously restrict the large-scale and sustainable application of the technology. Therefore, the development of low-energy consumption, high-efficiency separation, environmentally friendly materials, and the integration of new seawater desalination technologies with green energy has become a research direction that urgently needs to be broken through.

[0003] Solar energy, a green, clean, and renewable energy source, can evaporate water through photothermal conversion, making it a key development direction for efficient and energy-saving seawater desalination technology. In this process, photothermal conversion materials efficiently absorb solar radiation and convert it directly into heat, achieving precise heating of the air-water interface, thereby driving the phase change and separation of water molecules and achieving the selective extraction of seawater salt and fresh water. The performance of the evaporation system is closely related to the material's optical absorption properties, thermal conductivity, and mechanical stability. This makes the development of advanced materials with broad-spectrum light absorption, rapid thermal conductivity, and excellent structural strength a core research focus for solar desalination technology.

[0004] Current mainstream photothermal material systems primarily encompass four categories: metal-based materials, carbon-based materials, semiconductor-based materials, and organic polymer materials. These materials, through micro-nanostructure design and construction of three-dimensional evaporators, can achieve extremely high sunlight capture rates and significantly improved evaporation efficiency. For example, CN117306261A discloses a photothermal conversion material, its preparation method, evaporator, and applications. The preparation method comprises: providing a substrate having a porous structure; forming a polydopamine or polypyrrole layer on the surface of the substrate; and attaching carbon nanotubes and a photothermal enhancer to the polydopamine or polypyrrole layer to obtain the photothermal conversion material. However, in practical applications, the high production costs associated with the complex preparation process severely restrict its large-scale application. Furthermore, the material's insufficient mechanical strength and poor long-term operational stability pose significant challenges to its durability. Therefore, developing new green synthesis technologies to achieve the cost-effective and controllable preparation of high-performance photothermal conversion materials is of great practical significance for advancing breakthroughs in solar desalination technology.

[0005] Flexible polymer composite photothermal films, as a new type of desalination medium, have attracted significant attention in recent years due to their unique performance advantages. By combining functional photothermal components with flexible carriers such as polymers and cellulose, this type of material significantly improves the mechanical strength and interfacial stability of the material while retaining its photothermal conversion properties. Its breakthrough lies in the synergistic optimization of photothermal performance and structural toughness achieved through a simple preparation process, providing an innovative solution for the development of weather-resistant desalination equipment. Polypyrrole (PPy), an environmentally friendly conductive polymer material, constructs its unique conjugated structure system through oxidative polymerization under acidic conditions. The synergistic effect of its intrinsic conductive properties and photothermal conversion performance provides new possibilities for the construction of efficient desalination systems. The composite of polypyrrole with porous substrates such as seaweed cellulose and non-woven fabrics not only maintains the flexible characteristics of the substrate material, but also achieves synergistic photothermal-evaporation efficiency through optimized interfacial electron transport, resulting in excellent evaporation effects. For example, CN119191429A discloses a method for preparing a double-layer polypyrrole-deposited nickel foam and sodium alginate hydrogel solar evaporator. The method involves placing an electrodeposited polypyrrole nickel foam light-absorbing layer at the bottom of a container. A sodium alginate hydrogel is poured into the container from the surface of the electrodeposited polypyrrole nickel foam light-absorbing layer, forming a hydrogel layer on the upper surface of the electrodeposited polypyrrole nickel foam light-absorbing layer. The hydrogel layer is then allowed to stand at room temperature until bubbles in the hydrogel are expelled. A calcium chloride solution is added to the hydrogel layer along the inner wall of the container. The hydrogel layer is then allowed to stand at room temperature a second time. The sample is removed and soaked in distilled water, and the excess hydrogel is removed to obtain a double-layer polypyrrole-deposited nickel foam and sodium alginate hydrogel solar evaporator. CN110734575A discloses a method for preparing an aerogel-polypyrrole photothermal conversion material and its application. Using chitosan and PVA as substrates, a chitosan aerogel is prepared. Pyrrole is then added and in-situ polymerized with FeCl3, resulting in uniform adhesion to the chitosan aerogel, to obtain the aerogel-polypyrrole photothermal conversion material.

[0006] Enteromorpha (Ulva prolifera of Müller) is an algae plant in the Ulva family and genus Ulva. It is easily killed, but once the right conditions are met, it will reproduce continuously at a rapid rate. Excessive reproduction not only blocks the respiratory systems of organisms such as fish, causing their death, but also blocks sunlight from entering the water. Therefore, the management and resource utilization of Enteromorpha is also a matter of great significance. There are also many prior art reports on the resource utilization of Enteromorpha in photothermal materials. For example, CN117585751A discloses a Enteromorpha-derived carbon-based photothermal film and its application in seawater desalination. The Enteromorpha is dried and then carbonized at high temperature to obtain biochar. The resulting biochar is dispersed in distilled water to obtain a suspension, and the suspension is filtered through a polyvinylidene fluoride membrane to obtain a photothermal film. CN115448401A discloses a self-floating solar seawater evaporator with a jellyfish-like structure, its preparation method, and its application. The evaporator utilizes freeze-drying to produce aerogels from collected Enteromorpha cellulose, which are then carbonized to create an integrated Enteromorpha structure. However, existing techniques often carbonize Enteromorpha, which not only reduces mechanical strength but also compromises flexibility.

[0007] Therefore, how to fully utilize the biological properties of Enteromorpha to prepare flexible photothermal films, and how to improve the flexibility, mechanical properties and photothermal performance of the films while realizing resource utilization of Enteromorpha, is a key issue faced. To this end, the present invention is proposed. Summary of the Invention

[0008] In light of the state of the art, particularly the shortcomings of existing photothermal conversion materials, such as high cost, low stability, and insufficient flexibility, the present inventors conducted in-depth and extensive research in the field of photothermal conversion materials and discovered that direct interfacial polymerization of pyrrole with uncarbonized Enteromorpha powder not only enhances bonding strength and maintains good flexibility, while simultaneously achieving ecological management and resource utilization, but also exhibits excellent photothermal conversion performance. The present invention is based on these findings.

[0009] Therefore, one object of the present invention is to provide a flexible polypyrrole-modified Enteromorpha photothermal film, which is obtained by directly subjecting pyrrole to an interfacial polymerization reaction with uncarbonized Enteromorpha powder.

[0010] The second object of the present invention is to provide a method for preparing a flexible polypyrrole-modified enteromorpha photothermal film.

[0011] The third object of the present invention is to provide an application of a flexible polypyrrole-modified Enteromorpha photothermal film, which has a good effect in solar-driven seawater desalination.

[0012] The technical solutions for achieving the above-mentioned invention objectives can be summarized as follows:

[0013] A flexible polypyrrole-modified enteromorpha photothermal film is a polypyrrole particle layer in situ polymerized on the surface of an enteromorpha matrix.

[0014] According to the present invention, preferably, the particle size of the polypyrrole particles is 50-60 nm.

[0015] According to the present invention, preferably, the mass ratio of the polypyrrole particle layer to the enteromorpha matrix is ​​0.06-2:1, more preferably 0.3-1.5:1.

[0016] According to the present invention, preferably, the flexible polypyrrole-modified enteromorpha photothermal film further comprises a substrate, and the enteromorpha matrix with the in-situ polymerized polypyrrole particle layer is uniformly loaded on the surface of the substrate.

[0017] According to the present invention, preferably, the substrate is filter paper, non-woven fabric or polyurethane sponge.

[0018] According to the present invention, the method for preparing the flexible polypyrrole-modified enteromorpha photothermal film comprises the following steps:

[0019] Enteromorpha powder is added to hydrochloric acid for dispersion treatment, and then ammonium persulfate solution and pyrrole emulsion are added, and the mixture is stirred for polymerization reaction to obtain a film-forming liquid, and the film-forming liquid is formed into a film to obtain a flexible polypyrrole-modified enteromorpha photothermal film.

[0020] According to the present invention, preferably, the concentration of hydrochloric acid is 1-2 mol / L, more preferably 1.2 mol / L;

[0021] Preferably, the concentration of the ammonium persulfate solution is 4-5 mol / L, more preferably 4.2 mol / L;

[0022] Preferably, the concentration of the pyrrole emulsion is 0.2-0.3 mol / L, more preferably 0.21 mol / L.

[0023] According to the present invention, preferably, the molar ratio of pyrrole to ammonium persulfate is 0.3-2:1.

[0024] Preferably, the mass ratio of enteromorpha powder to pyrrole emulsion is 1:0.06-2, more preferably 1:0.3-1.5.

[0025] According to the present invention, preferably, the particle size of the Enteromorpha powder is 150-300 mesh.

[0026] According to the present invention, preferably, the preparation method of the flexible polypyrrole-modified enteromorpha photothermal film further includes the step of loading a substrate, loading the film-forming liquid on the substrate, and vacuum drying to obtain the flexible polypyrrole-modified enteromorpha photothermal film.

[0027] According to the present invention, preferably, the vacuum drying temperature is 60° C. to 70° C., and the vacuum drying time is 10 h to 15 h.

[0028] According to the present invention, the flexible polypyrrole-modified enteromorpha photothermal film is used for seawater desalination or high-salt wastewater desalination.

[0029] The beneficial effects of the present invention are as follows:

[0030] The flexible polypyrrole-modified Enteromorpha photothermal film of the present invention uses pyrrole as a modifier to directly modify the Enteromorpha, maintaining its biological flexibility and facilitating its application. The polypyrrole interacts with the Enteromorpha matrix through hydrogen bonds and hydroxyl groups, enhancing the mechanical properties of the photothermal film.

[0031] 2. The water droplets on the surface of the flexible polypyrrole-modified Enteromorpha photothermal film of the present invention can be completely absorbed within 6 seconds. The photothermal film has strong hydrophilicity, which ensures the water supply for interface evaporation and promotes the evaporation process.

[0032] 3. The flexible polypyrrole-modified Enteromorpha photothermal film of the present invention has good photothermal conversion performance. The low-salinity evaporation rate is stable at 1.9 kg·m under the illumination intensity of 1 sun. -2 ·h -1 About and no salt crystals.

[0033] 4. The polypyrrole / enteromorpha photothermal film obtained by the present invention exhibits excellent cycle stability and cleaning resistance after being applied to real seawater desalination. The seawater quality is effectively purified, the concentration of major cations is significantly reduced, and Na + The concentration can be reduced by more than 3 orders of magnitude. In the experiment, it showed excellent resistance to salt deposition, high mechanical strength, and strong cyclic stability, which can support large-scale production and use.

[0034] 5. The flexible polypyrrole-modified enteromorpha photothermal film of the present invention is environmentally friendly, non-toxic and harmless, and inexpensive, opening up a new way for the resource utilization of enteromorpha. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a graph comparing the evaporation rates of the cyclic evaporation experiment of the polypyrrole-modified carbonized Enteromorpha photothermal film in Comparative Example 1.

[0036] Figure 2 This is the SEM image of the flexible polypyrrole-modified Enteromorpha photothermal film in Experimental Example 1.

[0037] Figure 3 (a) Cross-sectional SEM (b) element distribution energy spectrum (cf) EDS scanning diagram of the flexible polypyrrole-modified Enteromorpha photothermal film in Experimental Example 1.

[0038] Figure 4 These are the FT-IR images corresponding to the flexible polypyrrole-modified enteromorpha photothermal films with different ratios in Experimental Example 4.

[0039] Figure 5 XPS images of the flexible polypyrrole-modified enteromorpha photothermal film in Experimental Example 1, as well as (a) XPS total spectrum, (b) C1s spectrum, (c) N 1s spectrum, and (d) O 1s spectrum.

[0040] Figure 6 Photos of the wetting process of the flexible polypyrrole-modified Enteromorpha photothermal film in Experimental Example 2 (a) before wetting and (b) after wetting.

[0041] Figure 7 This is the thermogravimetric analysis curve of the flexible polypyrrole-modified Enteromorpha photothermal film in Experimental Example 3.

[0042] Figure 8 This is the infrared thermal imaging image of the surface temperature of the flexible polypyrrole-modified enteromorpha photothermal film with different proportions in Experimental Example 4.

[0043] Figure 9 This is the absorption spectrum of the flexible polypyrrole-modified Enteromorpha photothermal film with different pyrrole / Enteromorpha ratios and different polymer loadings in Experimental Example 4.

[0044] Figure 10 (a) Evaporation rate comparison diagram and (b) mass change diagram of the flexible polypyrrole-modified Enteromorpha photothermal film in experimental example 5 in simulated seawater with different salt concentrations.

[0045] Figure 11 This is the evaporation rate diagram corresponding to the cyclic evaporation experiment of the flexible polypyrrole-modified Enteromorpha photothermal film in Experimental Example 5.

[0046] Figure 12 These are comparison photos of the flexible polypyrrole-modified Enteromorpha photothermal film before and after evaporation in Experimental Example 5.

[0047] Figure 13 The changes in the main cation concentrations before and after seawater desalination using the flexible polypyrrole-modified Enteromorpha photothermal membrane in Experimental Example 6.

[0048] Figure 14 This is a schematic structural diagram of the self-assembled solar energy simple interface evaporation collection device of the present invention. DETAILED DESCRIPTION

[0049] The present invention has conducted in-depth and extensive research in the field of photothermal conversion materials and found that directly conducting an interfacial polymerization reaction between pyrrole and uncarbonized Enteromorpha powder can not only enhance the bonding strength and maintain good flexibility, but also achieve ecological management and resource utilization simultaneously, and also has excellent photothermal conversion performance.

[0050] Photothermal and environmentally friendly composite membranes developed based on biomass resources are becoming an important breakthrough in this field. Taking the marine algae Enteromorpha as an example, this biomass, which has both ecological hazards and resource potential, contains rich polysaccharide segments, active functional groups, and natural fiber networks. Its three-dimensional multi-level pore structure and flexible properties can just make up for the shortcomings of traditional photothermal materials in terms of interfacial compatibility and mechanical durability. By directional regulation of its fiber-polymer composite structure, not only can the bonding strength between the photothermal active layer and the substrate be enhanced, but algae pollution can also be converted into functional raw materials, achieving simultaneous ecological governance and resource utilization.

[0051] Therefore, the present invention uses marine-derived Enteromorpha and pyrrole as raw materials, employing a polymer polymerization method to construct a polymer / Enteromorpha-based photothermal fiber membrane for solar-driven seawater desalination. The method is simple, low-cost, and environmentally friendly, resulting in excellent photothermal performance, high separation efficiency, and reusability.

[0052] The flexible polypyrrole-modified enteromorpha photothermal film of the present invention comprises an enteromorpha matrix surface on which a polypyrrole particle layer is in situ polymerized.

[0053] The Enteromorpha used in the present invention is not carbonized and reacts directly. Enteromorpha has good flexibility, and pyrrole directly undergoes interfacial polymerization with Enteromorpha to produce a flexible photothermal film. The interfacial polymerization reaction includes polymerization of pyrrole monomer itself, as well as copolymerization of pyrrole monomer with hydroxyl groups in Enteromorpha and cellulose. Polypyrrole binds to the Enteromorpha matrix through hydrogen bonds and hydroxyl group interactions.

[0054] In one or more preferred embodiments, the particle size of the polypyrrole particles is 50-60 nm.

[0055] In one or more preferred embodiments, the mass ratio of the polypyrrole particle layer to the enteromorpha matrix is ​​0.06-2:1, more preferably 0.3-1.5:1.

[0056] In one or more preferred embodiments, the flexible polypyrrole-modified enteromorpha photothermal film further comprises a substrate, and the enteromorpha matrix with the in-situ polymerized polypyrrole particle layer is uniformly loaded on the surface of the substrate.

[0057] In one or more preferred embodiments, the substrate is filter paper, non-woven fabric or polyurethane sponge.

[0058] According to the present invention, the method for preparing the flexible polypyrrole-modified enteromorpha photothermal film comprises the following steps:

[0059] Enteromorpha powder is added to hydrochloric acid for dispersion treatment, and then ammonium persulfate solution and pyrrole emulsion are added, and the mixture is stirred for polymerization reaction to obtain a film-forming liquid, and the film-forming liquid is formed into a film to obtain a flexible polypyrrole-modified enteromorpha photothermal film.

[0060] According to the present invention, Enteromorpha is treated with hydrochloric acid to remove inorganic salts attached to the surface and interior of Enteromorpha, and ammonium persulfate is used as an initiator and oxidant of the system to accelerate the polymerization process of pyrrole under weakly acidic conditions.

[0061] In one or more preferred embodiments, the concentration of hydrochloric acid is 1-2 mol / L, more preferably 1.2 mol / L;

[0062] Preferably, the concentration of the ammonium persulfate solution is 4-5 mol / L, more preferably 4.2 mol / L;

[0063] Preferably, the concentration of the pyrrole emulsion is 0.2-0.3 mol / L, more preferably 0.21 mol / L.

[0064] In one or more preferred embodiments, the molar ratio of pyrrole to ammonium persulfate is 0.3-2:1.

[0065] Preferably, the mass ratio of enteromorpha powder to pyrrole emulsion is 1:0.06-2, more preferably 1:0.3-1.5.

[0066] In one or more preferred embodiments, the particle size of the Enteromorpha powder is 150-300 mesh.

[0067] In one or more preferred embodiments, the preparation method of the flexible polypyrrole-modified enteromorpha photothermal film further includes the step of loading a substrate, loading the film-forming liquid on the substrate, and vacuum drying to obtain the flexible polypyrrole-modified enteromorpha photothermal film.

[0068] In one or more preferred embodiments, the vacuum drying temperature is 60° C. to 70° C., and the vacuum drying time is 10 h to 15 h.

[0069] According to the present invention, the flexible polypyrrole-modified enteromorpha photothermal film is used for seawater desalination or high-salt wastewater desalination.

[0070] In one or more preferred embodiments, a specific method for photothermal evaporation involves constructing a solar evaporation device comprising a foam ring, a cylindrical sponge, and a flexible polypyrrole-modified Enteromorpha photothermal film. The sponge contacts the flexible polypyrrole-modified Enteromorpha photothermal film and water, forming an I-shaped water supply. The wetted sponge continuously delivers water to the top surface of the photothermal film, enabling efficient photothermal evaporation.

[0071] The present invention will be further described below with reference to specific examples and drawings. These examples are merely descriptions of preferred implementations of the present invention, but do not limit the contents described below.

[0072] In the embodiment, fresh Enteromorpha from the coast of Binhai Park in Qingdao, Shandong Province was selected as raw material. A self-assembled solar simple interface evaporation collection device was used to test the performance. The device is shown in the figure. Figure 14 Evaporation performance tests, salt deposition resistance tests, and application experiments were all completed and data collected using this device. This device is only used to test the performance of the photothermal film and verify the desalination effect. The photothermal film prepared by this invention can be installed in similar desalination devices.

[0073] The self-assembled solar interface evaporation device consists of a solar simulator, an evaporator, and a data acquisition device. Simulated sunlight is provided by a xenon lamp with an AM1.5 filter, controlled to one sun using an optical power meter. The evaporator is a beaker, with tin foil used as insulation to reduce heat loss. A sponge strip cut to a suitable shape serves as a water channel to transport water and also provides support, positioning the photothermal film on top. Data acquisition is performed using an electronic analytical balance with an accuracy of 0.0001 g to record mass changes during evaporation, while a computer records mass losses at corresponding time points in real time. Each experiment was performed after the photothermal film was completely wetted to minimize the impact of the startup phase on the measured evaporation rate.

[0074] In the embodiment, one solar radiation intensity refers to 1 kW·m -2 .

[0075] Example 1

[0076] The preparation method of the flexible polypyrrole-modified enteromorpha photothermal film comprises the following steps:

[0077] (1) Use deionized water to repeatedly rinse the mud and sand and other impurities attached to the surface of the Enteromorpha, and place the washed Enteromorpha in a constant temperature forced air drying oven for continuous drying.

[0078] (2) The dried Enteromorpha was finely ground using a magnetic grinder and passed through a sieve to obtain 200-mesh homogenized Enteromorpha powder.

[0079] (3) Measure 200-mesh Enteromorpha powder and place it in a beaker. Add 1.2 mol / L dilute hydrochloric acid solution gradually and start the magnetic stirrer to disperse it for 10 min.

[0080] (4) Slowly add 4.2 mol / L ammonium sulfate solution and maintain constant temperature with magnetic stirring for 10 min.

[0081] (5) 0.21 mol / L pyrrole emulsion was continuously added to make the pyrrole monomer concentration in the reaction system 2.0 g / L, the reaction system was kept stably dispersed, and magnetic stirring was performed for 2 h to obtain a mixed solution.

[0082] (6) 10 ml of the mixed solution was evenly loaded on the surface of the filter paper substrate, and then the flexible polypyrrole-modified Enteromorpha photothermal film was obtained by vacuum drying.

[0083] In this embodiment, the molar ratio of pyrrole to ammonium persulfate is 1:2, and the mass ratio of enteromorpha powder to pyrrole emulsion is 3:2.

[0084] For the convenience of illustration, the mass ratio of enteromorpha powder to pyrrole emulsion is 3:2, and the flexible polypyrrole-modified enteromorpha photothermal film with a pyrrole monomer concentration of 2.0 g / L is recorded as 2.0PPy@EP.

[0085] Example 2

[0086] The method for preparing the flexible polypyrrole-modified enteromorpha photothermal film is the same as that described in Example 1, except that:

[0087] In step (4), the concentration ratio of the pyrrole emulsion to ammonium persulfate is 2:1. The amounts used in the remaining reactions are exactly the same as those in Example 1.

[0088] Example 3

[0089] The method for preparing the flexible polypyrrole-modified enteromorpha photothermal film is the same as that described in Example 1, except that:

[0090] In step (4), the concentration ratio of the pyrrole emulsion to ammonium persulfate is 1:1. The amounts used in the remaining reactions are exactly the same as those in Example 1.

[0091] Example 4

[0092] The method for preparing the flexible polypyrrole-modified enteromorpha photothermal film is the same as that described in Example 1, except that:

[0093] In step (6), the volume of the solution loaded on the surface of the basement membrane is 5 ml, and the amounts used in the remaining reactions are exactly the same as those in Example 1.

[0094] Example 5

[0095] The method for preparing the flexible polypyrrole-modified enteromorpha photothermal film is the same as that described in Example 1, except that:

[0096] In step (6), the volume of the solution loaded on the surface of the basement membrane is 15 mL, and the amounts used in the remaining reactions are exactly the same as those in Example 1.

[0097] Example 6

[0098] The preparation method of the flexible polypyrrole-modified Enteromorpha photothermal film is the same as that described in Example 1, except that: in step (5), pyrrole emulsion is added so that the concentration of pyrrole monomer is 0.2, 0.7, 1.0, 1.5, and 4.0 g / L, thereby changing the ratio of pyrrole to Enteromorpha. The remaining reactions and the dosages are exactly the same as those in Example 1. The mass ratios of Enteromorpha powder and pyrrole emulsion are 3:0.2, 3:0.7, 3:1, 3:1.5, and 3:4, respectively. The flexible polypyrrole-modified Enteromorpha photothermal films obtained are recorded as 0.2PPy@EP, 0.7PPy@EP, 1.0PPy@EP, 1.5PPy@EP, and 4.0PPy@EP, respectively.

[0099] Comparative Example

[0100] The polypyrrole-modified enteromorpha photothermal film was prepared using the enteromorpha carbonized at low temperature. The preparation steps are as follows:

[0101] (1) The 200-mesh homogenized Enteromorpha powder obtained in step (2) of Example 1 was placed in a constant temperature forced air drying oven and dried continuously.

[0102] (2) The dried Enteromorpha powder was placed in a tubular furnace and subjected to low-temperature carbonization treatment under the protection of nitrogen. The temperature was controlled at 200 °C and the duration was 2 h.

[0103] (3) Measure the carbonized Enteromorpha powder and put it into a beaker. Add 1.2 mol / L dilute hydrochloric acid solution gradually and start the magnetic stirrer to disperse it for 10 min.

[0104] (4) Slowly add 4.2 mol / L ammonium sulfate solution and maintain constant temperature with magnetic stirring for 10 min.

[0105] (5) 0.21 mol / L pyrrole emulsion was continuously added to make the pyrrole monomer concentration in the reaction system 2.0 g / L, the reaction system was kept stably dispersed, and magnetic stirring was performed for 2 h to obtain a mixed solution.

[0106] (6) 10 ml of the mixed solution was evenly loaded on the surface of the filter paper substrate to obtain the finished product of the polypyrrole-modified carbonized Enteromorpha photothermal film.

[0107] In this comparative example, the molar ratio of each component is the same as that in Example 1, the molar ratio of pyrrole to ammonium persulfate is 1:2, and the mass ratio of enteromorpha powder to pyrrole emulsion is 3:2.

[0108] The photothermal performance and reusability of the polypyrrole-modified carbonized enteromorpha photothermal film prepared in this comparative example were tested. Figure 1 As shown. Figure 1 It can be seen that the initial evaporation rate of the carbonized Enteromorpha photothermal film modified with polypyrrole is high, reaching 2.65 kg·m -2 ·h -1As the number of repeated evaporations increases, the evaporation rate of the photothermal film slowly decreases, and the film surface also becomes damaged and cracked after drying. This is because during the carbonization process, the high temperature destroys the hydrophilic components (polysaccharides, proteins, etc.) in the Enteromorpha, forming a hydrophobic structure that weakens adhesion. At the same time, the Enteromorpha fiber structure collapses, the surface becomes smooth, and the mechanical interlocking effect between the film and the Enteromorpha is weakened.

[0109] Judging from the performance shown in the comparative example, although the carbonized Enteromorpha is black in color and has strong light absorption ability, and its evaporation ability masks the water transport loss caused by the enhanced hydrophobicity, the material's repeated stability and mechanical strength are very poor, making it difficult to cope with large-scale storage and transportation. Adhesives need to be added to ensure the functional integrity of the material, and there is room for improvement.

[0110] Test Example 1, Electron Microscope Image

[0111] The SEM microscopic analysis of the flexible polypyrrole-modified enteromorpha photothermal film prepared in Test Example 1 is as follows: Figure 2 As shown. Figure 2 It can be seen that the polypyrrole nanoparticles formed on the surface of Enteromorpha (EP) by in situ polymerization exhibit an irregular spherical configuration. Their submicron size and three-dimensional cross-linked network structure significantly increase the effective light-receiving area of ​​the material. Further observation shows that a polypyrrole coating with good continuity is formed on the surface of the substrate, with only a very small proportion of uncoated areas. The particles exhibit directional aggregation characteristics at the interface. This structural feature originates from the self-assembly behavior of the conductive polymer chain caused by the intermolecular π-π interaction during the polymerization process. The staged deposition mechanism of polypyrrole has a regulatory effect on the pore structure of the base film. The nanoparticles generated in the early stage mainly fill the large-sized pores. The subsequent growth process constructs a multi-level pore system through the bridging effect. This micro-nano synergistic structure optimizes the water transfer path, especially the pore network formed in the evaporation interface area, which significantly improves the liquid phase transport efficiency.

[0112] The cross-sectional SEM, element distribution spectrum and EDS scanning images of the flexible polypyrrole modified enteromorpha photothermal film prepared in Example 1 are shown in FIG. Figure 3 As shown. Figure 3 EDS surface analysis confirms that the surface of the flexible polypyrrole-modified Enteromorpha photothermal film exhibits a homogeneous distribution of C, N, and O elements, with corresponding atomic percentages of 64.77% (C), 2.15% (N), and 33.08% (O), respectively. The stable presence of the characteristic nitrogen element confirms the successful chemical grafting of polypyrrole to the Enteromorpha matrix. This quantitative result, corroborated by XPS depth profiling data, reveals the molecular-level interfacial bonding of the polypyrrole-modified component to the substrate surface, demonstrating that the present invention effectively loads the pyrrole and Enteromorpha polymer onto the substrate.

[0113] (a) XPS total spectrum (b) C 1s spectrum (c) N 1s spectrum (d) O 1s spectrum of the flexible polypyrrole-modified enteromorpha photothermal film prepared in Example 1 Figure 5 As shown. Figure 5 It can be seen that the XPS fine spectrum analysis shows that the C1s spectrum at 283.23 eV, 284.84 eV and 286.74 eV correspond to the characteristic peaks of CC / CH bond, CO / CN bond and C=O bond respectively. The characteristic peak at 397.02 eV in the N1s spectrum confirms the existence of imine bond (─N==) in the pyrrole ring, and the triplet peak in the range of 398.23-399.70 eV corresponds to oxidized nitrogen (N*), which accounts for 81%. The results show that there is a significant conjugated defect structure in the polypyrrole skeleton. The O 1s spectrum quadruple splitting feature acquired simultaneously is consistent with the 3450 cm-1 peak in the FT-IR spectrum. -1 The hydroxyl stretching vibration peak at 1630 cm⁻¹ and the quinone carbonyl vibration peak at 1630 cm⁻¹ jointly confirm that the polypyrrole-modified Enteromorpha component is stably loaded onto the basement membrane surface through chemical bonding. The gradient wetting effect created by the hydroxyl groups at the solid-liquid interface synergistically amplifies the capillary force of the water transport channel and the effective contact area of ​​the evaporation interface, ultimately achieving a breakthrough improvement in photothermal evaporation performance.

[0114] Test Example 2: Contact Angle Test

[0115] Contact angle test of flexible polypyrrole modified enteromorpha photothermal film with different ratios Figure 6 As shown. Figure 6 Tests show that the droplet penetration time is always within 6 seconds, and the PPy / EP composite system exhibits superhydrophilic properties (droplet contact angle τ≤9.8°).

[0116] Test Example 3: Thermal stability test

[0117] The thermogravimetric analysis of the flexible polypyrrole-modified enteromorpha photothermal film prepared in Test Example 1 is as follows: Figure 7 As shown. Figure 7 It can be seen that with the increase of temperature, the mass of the flexible polypyrrole-modified Enteromorpha photothermal film does not change significantly below 250°C, and it has high thermal stability; after the temperature rises to 250°C, it loses weight rapidly, indicating that the thermal stability of the photothermal film can meet the requirements of solar-driven interface evaporation.

[0118] Test Example 4: Optical Performance Test

[0119] The FT-IR curves of flexible polypyrrole modified enteromorpha photothermal films with different ratios were tested, such as Figure 4 As shown. Figure 4It can be seen that the spectral analysis confirmed that the biomass matrix showed a typical polysaccharide hydroxyl OH stretching vibration mode at 3331 cm⁻¹, a methylene CH symmetric vibration characteristic at 2915 cm⁻¹, and a 1200-1000 cm⁻¹. -1 The broad absorption band corresponds to the COC vibration of the sugar ring. The characteristic vibration mode of polypyrrole is at 1631 cm -1 (conjugated C=C skeleton vibration), 1536 cm -1 (pyrrole ring breathing vibration), 1155 cm -1 (CN polar bond vibration) and 917 cm -1 (CH deformation vibration outside the ring plane) is clear, and this vibration mode change reveals the existence of strong intermolecular interaction between polypyrrole and biomass carrier (calculated hydrogen bond binding energy value is 2.34 eV). Figure 4 (a), Figure 4 (b) FT-IR spectra of samples with varying ratios of Enteromorpha to pyrrole. All FT-IR curves correspond to characteristic peaks of the PPy@EP polymerization product, and some peaks intensify as the ratio increases. This demonstrates that the components are successfully loaded onto the photothermal film surface, and that photothermal films with varying pyrrole / Enteromorpha ratios can be successfully prepared.

[0120] The temperature rise of flexible polypyrrole modified enteromorpha photothermal films with different ratios was tested under a standard sunlight intensity, such as Figure 8 As shown. Figure 8 The film system exhibits excellent photothermal response dynamics, completing 90% of the temperature rise within 10 seconds and ultimately reaching a steady-state surface temperature of 90°C. When the pyrrole / enteromorpha mass ratio increases from 0.2 to 1.5, the steady-state temperature exhibits a significant linear positive correlation with the mass ratio, demonstrating the excellent photothermal performance of the polypyrrole / enteromorpha film.

[0121] The UV-visible-near infrared spectra of flexible polypyrrole modified enteromorpha photothermal films with different ratios were tested, such as Figure 9 As shown. Figure 9 The results show that the photothermal film loaded with the Enteromorpha / polypyrrole component exhibited significantly enhanced light absorption within the 200-2500 nm spectral range, with absorbance increasing by 2.1 times compared to the blank control. As the pyrrole / polypyrrole mass ratio increased, the material's peak absorbance in the near-infrared region (980 nm) reached 97.8%, and its absorption efficiency in the visible region (550 nm) increased by 41%, confirming a positive correlation between the active component content and the spectral response intensity. This trend confirms the quantitative correlation between photothermal conversion efficiency and active material loading.

[0122] Test Example 5: Salt Deposition Resistance Test

[0123] The flexible polypyrrole-modified Enteromorpha photothermal film prepared in Example 1 was used for seawater desalination. The evaporation rate of simulated seawater with different salt concentrations (a) and the mass change (b) were tested. Figure 10 As shown. Figure 10 It can be seen that the photothermal film simulates seawater and maintains excellent evaporation performance under the irradiation intensity of 1 sun: the evaporation rate is stable at 1.9 kg·m -2 ·h -1 There is no salt crystallization, and the salinity remains at 1.7 kg·m -2 ·h -1 This is mainly due to the temperature gradient formed by the Enteromorpha / polypyrrole component, which prompts the salt to migrate and deposit toward the edge of the blank filter paper. Comparative experiments show that after removing the blank edge, the evaporation rate is significantly reduced and large areas of salt crystals appear on the membrane surface, confirming that the edge area effectively maintains the continuous evaporation capacity of the photothermal interface by constructing a salt migration buffer zone.

[0124] A 5-day continuous photothermal-cleaning cycle test was conducted on real seawater. The results are as follows: Figure 11 As shown. Figure 11 It can be seen that the evaporation rate of the flexible polypyrrole modified Enteromorpha photothermal film sample is stably maintained at 1.93 kg·m -2 ·h -1 . Figure 12 This is a photo of the flexible polypyrrole-modified Enteromorpha photothermal film after the cycle test. The salt crystal coverage on the membrane surface is low and can be well removed after cleaning; the material's geometric integrity retention rate is very high; this proves that the flexible polypyrrole-modified Enteromorpha photothermal film has reliable cycle stability and salt corrosion resistance in actual application scenarios.

[0125] Test Example 6: Ion Removal

[0126] The flexible polypyrrole modified enteromorpha photothermal film prepared in Example 1 was subjected to ICP-OES detection, and the results were as follows: Figure 13 As shown. Figure 13 It can be seen that the main cations (Na + Mg 2+ , K + , Ca 2+ ) concentrations decreased by orders of magnitude, with sodium ions almost completely removed. Key pollutant concentrations exceeded the limits set by the WHO Guidelines for Drinking Water Quality (GDWQ), demonstrating the highly efficient desalination and mineral separation capabilities of this CTM system.

Claims

1. Flexible polypyrrole-modified enteromorpha photothermal film, characterized in that: The photothermal film is a polypyrrole particle layer in situ polymerized on the surface of an enteromorpha matrix.

2. The flexible polypyrrole-modified enteromorpha photothermal film according to claim 1, characterized in that: The particle size of polypyrrole particles is 50-60 nm.

3. The flexible polypyrrole-modified enteromorpha photothermal film according to claim 1, characterized in that: The mass ratio of the polypyrrole particle layer to the enteromorpha matrix is ​​0.06-2:

1.

4. The flexible polypyrrole-modified enteromorpha photothermal film according to claim 1, characterized in that: The flexible polypyrrole-modified enteromorpha photothermal film further comprises a substrate, and the enteromorpha matrix with the in-situ polymerized polypyrrole particle layer is uniformly loaded on the surface of the substrate; preferably, the substrate is filter paper, non-woven fabric or polyurethane sponge.

5. The method for preparing the flexible polypyrrole-modified enteromorpha photothermal film according to any one of claims 1 to 4, comprising the following steps: Enteromorpha powder is added to hydrochloric acid for dispersion treatment, and then ammonium persulfate solution and pyrrole emulsion are added, and the mixture is stirred for polymerization reaction to obtain a film-forming liquid, and the film-forming liquid is formed into a film to obtain a flexible polypyrrole-modified enteromorpha photothermal film.

6. The method for preparing the flexible polypyrrole-modified enteromorpha photothermal film according to claim 5, characterized in that: The concentration of hydrochloric acid is 1-2 mol / L, the concentration of ammonium persulfate solution is 4-5 mol / L, and the concentration of pyrrole emulsion is 0.2-0.3 mol / L.

7. The method for preparing the flexible polypyrrole-modified enteromorpha photothermal film according to claim 5, characterized in that: The molar ratio of pyrrole to ammonium persulfate is 0.3-2:1; preferably, the mass ratio of enteromorpha powder to pyrrole emulsion is 1:0.06-2.

8. The method for preparing the flexible polypyrrole-modified enteromorpha photothermal film according to claim 5, characterized in that: The preparation method of the flexible polypyrrole-modified enteromorpha photothermal film further includes the step of loading a substrate, loading the film-forming liquid on the substrate, and vacuum drying to obtain the flexible polypyrrole-modified enteromorpha photothermal film.

9. The method for preparing the flexible polypyrrole-modified enteromorpha photothermal film according to claim 5, characterized in that: The vacuum drying temperature is 60℃~70℃, and the vacuum drying time is 10h-15h.

10. The use of the flexible polypyrrole-modified enteromorpha photothermal film according to any one of claims 1 to 4, characterized in that: Used for seawater desalination or high-salt wastewater desalination.

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