Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability and preparation method of Z-type heterojunction photocatalytic evaporator

Abstract

The invention discloses a preparation method of a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability. The preparation method comprises the following steps: 1, grinding melamine powder and sodium chloride, and uniformly mixing; step 2, putting the uniformly mixed medicines into a muffle furnace for reaction; step 3, taking out a reactant, washing with water, centrifuging and drying to obtain porous g-C3N4; step 4, adding sodium alginate into water to form a uniform and transparent solution; step 5, sequentially adding a pyrrole monomer Py and the porous g-C3N4 into the uniform and transparent solution, and mixing to prepare homogeneous slurry; step 6, infiltrating melamine foam into the homogenized slurry, and transferring the melamine foam into a CaCl2 solution to carry out first-step cross-linking immobilization; and 7, further treating the sample subjected to calcium ion crosslinking treatment in a FeCl3. 6H2O solution to obtain the Z-type heterojunction photocatalytic evaporator material. The preparation method has the characteristics of simple preparation process, high environmental adaptability and stable structure.

Description

Technical Field

[0001] This invention belongs to the technical field of hydrogel photocatalytic evaporators, specifically relating to a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability and its preparation method. Background Technology

[0002] Current solar thermal evaporation technology faces severe challenges in its path towards practical application, including material durability, system stability, and environmental adaptability. Specifically, during seawater desalination, evaporation channels are easily blocked by salt crystals, leading to impeded water transport and a sharp drop in efficiency. Furthermore, the core photothermal components undergo photodegradation under prolonged exposure to strong ultraviolet radiation, causing a decline in their conversion performance. In addition, organic matter, oil, and microorganisms in natural water bodies easily adhere to the evaporator surface, forming biofouling that not only blocks light and reduces efficiency but may also cause secondary pollution.

[0003] Patent CN117534160A discloses a wood-based composite material with both water evaporation and photocatalytic functions, and its preparation method. This material uses low-cost wood as a substrate, forms a photothermal layer by impregnating it with carbon nanotubes, and grows MnO2 particles in situ on the surface, constructing a three-dimensional solar interface evaporation structure that integrates mass transfer and water conduction functions. It can achieve simultaneous water evaporation and pollutant degradation under light irradiation, exhibiting excellent water purification performance. However, wood, as a substrate material, is prone to expansion and structural collapse under long-term humid and hot conditions and light irradiation, resulting in poor overall stability.

[0004] Patent CN120398170A discloses a solar water evaporator constructed based on carbon-based photothermal materials such as carbon nanotubes, micron-sized porous hydrogels, and porous salt-suppressing mineral powders. This device significantly improves evaporation efficiency by optimizing water transport and steam diffusion channels, and effectively suppresses salt accumulation by utilizing the surface charge effect of the mineral powders. Simultaneously, a conical structure with a height-to-diameter ratio of 1.25 is employed to achieve automatic salt crystal shedding through gravity. However, this technology primarily targets the suppression of inorganic salts and does not address the photocatalytic degradation of organic pollutants.

[0005] The aforementioned solar evaporators have low mechanical strength, complex manufacturing processes, and high costs due to the use of carbon nanotubes. Their long-term reliability in photothermal synergistic photocatalytic water treatment is questionable and requires further improvement.

[0006] Hydrogels have the characteristics of high water content, good thermal management and environmental friendliness. However, pure hydrogels usually have insufficient mechanical strength and poor environmental adaptability, making them difficult to use in complex environments for a long time. Summary of the Invention

[0007] In order to overcome the problems existing in the prior art, the purpose of this invention is to provide a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability and its preparation method. The preparation method has the characteristics of simple preparation process, strong environmental adaptability and structural stability.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability includes the following steps; Step 1: Place melamine powder and sodium chloride in a mortar and grind them until they are evenly mixed; Step 2: Place the well-mixed reagents in a covered crucible and put it into a muffle furnace for reaction; Step 3: Remove the reactants, wash with water, centrifuge and dry to obtain porous g-C3N4; Step 4: Add sodium alginate to an appropriate amount of water and stir under constant temperature and magnetic stirring conditions until it is fully dissolved to form a uniform and transparent solution; Step 5: Add pyrrole monomer Py and the porous g-C3N4 sequentially to the above uniform and transparent solution, and continue to mix using a constant temperature magnetic stirrer to obtain a homogeneous slurry; Step 6: Impregnate the pre-cut melamine foam with the homogeneous slurry and transfer it to a CaCl2 solution for the first step of crosslinking and fixation; Step 7: The sample after calcium ion crosslinking treatment is further treated in FeCl3·6H2O solution to finally obtain a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability.

[0009] Preferably, in step 1, the mass ratio of melamine powder to sodium chloride is 3:1 to 1:3, and the grinding time is 30-90 min.

[0010] Preferably, in step 2, the heating rate of the muffle furnace reaction is 1-5 °C / min, the holding temperature is 400-600 °C, and the reaction time is 1-5 h.

[0011] Preferably, in step 3, the drying reaction time is 6 h and the drying temperature is 60 ℃.

[0012] Preferably, in step 4, the sodium alginate raw material is a byproduct of the extraction of iodine and mannitol from brown algae such as kelp or Sargassum.

[0013] Preferably, in step 4, the temperature of the constant temperature magnetic stirrer is 25 ℃, and the holding time is 2~15 h.

[0014] Preferably, in step 5, the porous g-C3N4 mass is 0.01~0.2 g / mL; the concentration of the solution for dissolving Py is 0.02~0.2 g / mL; the temperature of the constant temperature magnetic stirrer is 0 ℃; and the stirring time is 1-3 h.

[0015] Preferably, in step 6, the concentration of the solution for dissolving CaCl2 is 0.02 g / mL, the temperature of the constant-temperature magnetic stirrer is 0 ℃, and the holding time is 0.5 h.

[0016] In step 6, the melamine foam has a size of 2 cm × 2 cm × 3 cm.

[0017] In step 6, Ca 2+ The cross-linking time is 1~3 h.

[0018] Preferably, in step 7, the concentration of FeCl3·6H2O solution is 2 mol / L, and the oxidation time is 2~8 h.

[0019] A Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability. The evaporator includes the micron-scale macroporous structure of the sponge itself and the sheet structure formed by in-situ cross-linking of sodium alginate. The sheet structure opens the macropores of the sponge to the segmentation, forming a more diverse pore structure. Carbon nitride and polypyrrole are distributed on the surface of the sponge skeleton and the sheet formed by sodium alginate. This evaporator uses sodium alginate hydrogel as a matrix, which not only creates a highly efficient water transport channel but also provides excellent thermal management capabilities. In Fe... 3+ Under the influence of light, the hydrogel forms a unique "eggshell" fragmented structure, further enhancing capillary forces and optimizing the water transport mechanism. The Z-shaped heterojunction structure formed after oxidation successfully integrates photocatalytic and photothermal functions: on the one hand, it utilizes the temperature gradient and gravity within the hydrogel to achieve ion exchange; on the other hand, under light irradiation, the Z-shaped heterojunction constructed from PPy-CN can generate superoxide radicals (·O2). -) It effectively degrades antibiotic wastewater by reacting with hydroxyl radicals (·OH). This evaporator exhibits good adaptability to complex environments and shows broad application prospects in the field of sustainable solar-driven wastewater treatment.

[0020] The beneficial effects of this invention are: This invention utilizes melamine foam as a supporting framework, effectively addressing the insufficient mechanical strength of hydrogel materials and significantly enhancing the overall structural stability of the evaporator. Sodium alginate hydrogel serves as a carrier, firmly encapsulating porous g-C3N4 onto the foam framework surface, thereby reducing the risk of active components detaching during long-term operation. The Z-shaped heterojunction structure constructed from the oxidized porous g-C3N4 and polypyrrole (PPy) promotes photogenerated electron-hole pairs (e-hole pairs).- / h + This evaporator achieves efficient separation, thereby enhancing photocatalytic performance. Its simple fabrication process, good environmental adaptability, high photothermal conversion efficiency, excellent mechanical stability, and photocatalytic activity demonstrate broad application potential in seawater desalination and antibiotic wastewater treatment.

[0021] Because the presence of Ppy can convert solar energy into heat energy, forming a photothermal layer, the heating of the photothermal layer in this invention facilitates photocatalytic reactions. 1. The contribution of the photothermal effect provides "thermal energy drive" for the catalytic reaction, accelerating molecular motion and lowering the reaction energy barrier. 2. It accelerates carrier separation and migration; heat can provide additional energy for electrons in the semiconductor, helping them transition from the valence band to the conduction band, or be released from defect states, thereby increasing the concentration of photogenerated carriers. Heating can accelerate the lattice vibrations of photogenerated electrons and holes, helping them to quickly escape recombination centers and migrate to the surface, greatly improving charge separation efficiency. In high-concentration brine tolerance tests, the sample was continuously evaporated in a 25% sodium chloride solution for 8 hours, and no obvious salt crystal precipitation was observed on its surface.

[0022] Under simulated industrial wastewater containing high concentrations of ciprofloxacin and tetracycline, this material system exhibits a significant photothermal-photocatalytic synergistic effect, with pollutant degradation efficiency far exceeding that of a single photocatalytic process. This hydrogel material, combining efficient photothermal conversion and photocatalytic synergistic performance, possesses advantages such as environmental friendliness, simple preparation process, and low cost, demonstrating good potential for industrial application and showing broad application prospects in the treatment of recalcitrant antibiotic wastewater. Attached Figure Description

[0023] Figure 1 The evaporation rate of a Z-type heterojunction photocatalytic evaporator under different solution environments under one sun.

[0024] Figure 2 The concentration of heavy metal ions in the solution before and after one sun exposure is given.

[0025] Figure 3 To enhance the salt resistance of the prepared photocatalytic evaporator.

[0026] Figure 4 The curves of the photocatalytic evaporator prepared in the photocatalytic and photothermal synergistic effect degrading 40 mg / L ciprofloxacin solution are shown.

[0027] Figure 5 SEM image of the prepared photocatalytic evaporator. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings.

[0029] Example 1 6.0 g of melamine Sodium chloride 2.0 g Grinding time 30 min The muffle furnace heating rate is 2 °C / min The muffle furnace has an insulation temperature of 400℃. The muffle furnace should be kept warm for 1 hour. Sodium alginate 0.2 g 10 mL of deionized water Thermostatic magnetic stirrer heats up for 2 hours Pyrrole 0.4 g Porous g-C3N40.2 g Crosslinking time 1 h Oxidation time: 2 hours Melamine foam 2 cm × 2 cm × 3 cm Weigh 6.0 g of melamine and 2.0 g of sodium chloride, and grind them evenly in an agate mortar for 30 min. Transfer the mixture to a crucible and place it in a muffle furnace. Heat at a rate of 2 °C / min and hold at 400 °C for 1 h. After the reaction is complete, remove the product, centrifuge and wash it several times, and then dry it in an oven at 60 °C for 6 h.

[0030] Sodium alginate was completely dissolved in deionized water using a thermostatic magnetic stirrer at 0 °C for 2 h. 0.2 g of porous g-C3N4 and 0.4 g of pyrrole were then added and stirred at the same temperature to ensure uniform dispersion of the pyrrole and porous g-C3N4.

[0031] The melamine foam impregnated with the above homogeneous solution was cross-linked by immersing it in a 0.02 g / mL calcium chloride solution for 1 h. The cross-linked melamine foam was then oxidized by immersing it in a 2 mol / L FeCl3·6H2O solution for 2 h. This yielded a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability.

[0032] like Figure 1 The figure shows the evaporation rate of a Z-type heterojunction photocatalytic evaporator under different solution conditions under one sun exposure. (See attached figure.) Figure 1 It can be seen that the evaporation rate of this Z-type heterojunction photocatalytic evaporator remains basically unchanged in solutions with different environments.

[0033] Example 2 8.0 g of melamine Sodium chloride 8.0 g Grinding time 60 min The muffle furnace heating rate is 3 °C / min The muffle furnace has an insulation temperature of 500℃. The muffle furnace should be kept warm for 2 hours. Sodium alginate 0.2 g 10 mL of deionized water Thermostatic magnetic stirrer heats up for 5 hours Pyrrole 0.7 g Porous g-C3N40.3 g Crosslinking time 1 h Oxidation time: 4 h Melamine foam 2 cm × 2 cm × 3 cm Weigh 8.0 g of melamine and 8.0 g of sodium chloride, and grind them evenly in an agate mortar for 60 min. Transfer the mixture to a crucible and place it in a muffle furnace. Heat at a rate of 3 °C / min and hold at 500 °C for 2 h. After the reaction is complete, remove the product, centrifuge and wash it several times, and then dry it in an oven at 60 °C for 6 h.

[0034] Sodium alginate was completely dissolved in deionized water using a thermostatic magnetic stirrer at 0 °C for 5 h. 0.3 g of porous g-C3N4 and 0.7 g of pyrrole were then added and stirred at the same temperature to ensure uniform dispersion of the pyrrole and porous g-C3N4.

[0035] The melamine foam impregnated with the above homogeneous solution was cross-linked by immersing it in a 0.02 g / mL calcium chloride solution for 2 h. The cross-linked melamine foam was then oxidized by immersing it in a 2 mol / L FeCl3·6H2O solution for 4 h. This yielded a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability.

[0036] like Figure 2 The figure shows the ion concentrations of heavy metal ions in a solution before and after one solar exposure. (From the attached image) Figure 2 It can be seen that the ion content in the solution is significantly reduced after evaporation and collection by the Z-type heterojunction photocatalytic evaporator.

[0037] Example 3 10.0 g of melamine Sodium chloride 12.0 g Grinding time 60 min The muffle furnace heating rate is 3 °C / min The muffle furnace has an insulation temperature of 550℃. The muffle furnace should be kept warm for 3 hours. Sodium alginate 0.4 g 20 mL of deionized water Thermostatic magnetic stirrer heats up for 8 hours Pyrrole 2.0 g Porous g-C3N4 1.0 g Crosslinking time 2 h Oxidation time 5 h Melamine foam 2 cm × 2 cm × 3 cm Weigh 10.0 g of melamine and 12.0 g of sodium chloride, and grind them evenly in an agate mortar for 60 min. Transfer the mixture to a crucible and place it in a muffle furnace. Heat at a rate of 3 °C / min and hold at 550 °C for 3 h. After the reaction is complete, remove the product, centrifuge and wash it several times, and then dry it in an oven at 60 °C for 6 h.

[0038] Sodium alginate was completely dissolved in deionized water using a thermostatic magnetic stirrer at 0 °C for 8 h. 1.0 g of porous g-C3N4 and 2.0 g of pyrrole were then added and stirred at the same temperature to ensure uniform dispersion of the pyrrole and porous g-C3N4.

[0039] The melamine foam impregnated with the above homogeneous solution was cross-linked by immersing it in a 0.02 g / mL calcium chloride solution for 2 h. The cross-linked melamine foam was then oxidized by immersing it in a 2 mol / L FeCl3·6H2O solution for 5 h. This yielded a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability.

[0040] like Figure 3 The image shows the high salt resistance of the prepared photocatalytic evaporator. (From the attached image...) Figure 3 It can be seen that the Z-type heterojunction photocatalytic evaporator did not show obvious salt crystallization on its surface after 8 hours in sodium chloride solutions of different mass fractions under one sun.

[0041] Example 4 10.0 g of melamine Sodium chloride 15.0 g Grinding time 80 min The muffle furnace heating rate is 3 °C / min The muffle furnace has an insulation temperature of 550℃. The muffle furnace should be kept warm for 3 hours. Sodium alginate 0.4 g 20 mL of deionized water Thermostatic magnetic stirrer, heat preservation time 11 hours Pyrrole 3.0 g Porous g-C3N4 1.0 g Crosslinking time 2 h Oxidation time: 4 h Melamine foam 2 cm × 2 cm × 3 cm Weigh 10.0 g of melamine and 15.0 g of sodium chloride, and grind them evenly in an agate mortar for 80 min. Transfer the mixture to a crucible and place it in a muffle furnace. Heat at a rate of 3 °C / min and hold at 550 °C for 3 h. After the reaction is complete, remove the product, centrifuge and wash it several times, and then dry it in an oven at 60 °C for 6 h.

[0042] Sodium alginate was completely dissolved in deionized water using a thermostatic magnetic stirrer at 0 °C for 8 h. 1.0 g of porous g-C3N4 and 3.0 g of pyrrole were then added and stirred at the same temperature to ensure uniform dispersion of the pyrrole and porous g-C3N4.

[0043] The melamine foam impregnated with the above homogeneous solution was cross-linked by immersing it in a 0.02 g / mL calcium chloride solution for 2 h. The cross-linked melamine foam was then oxidized by immersing it in a 2 mol / L FeCl3·6H2O solution for 4 h. This yielded a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability.

[0044] like Figure 4 The figure shows the degradation curve of 40 mg / L ciprofloxacin solution by the prepared photocatalytic evaporator under the synergistic effect of photocatalysis and photothermal action. (See attached figure.) Figure 4 It can be seen that the photocatalytic evaporator has excellent photocatalytic and photothermal synergistic degradation capabilities.

[0045] Example 5 5.0 g of melamine Sodium chloride 15.0 g Grinding time 90 min The muffle furnace heating rate is 5 °C / min The muffle furnace has an insulation temperature of 600℃. The muffle furnace should be kept warm for 5 hours. Sodium alginate 0.2 g 10 mL of deionized water Thermostatic magnetic stirrer, heat preservation time 15 hours Pyrrole 2.0 g Porous g-C3N4 1.0 g Crosslinking time 3 h Oxidation time 8 h Melamine foam 2 cm × 2 cm × 3 cm Weigh 5.0 g of melamine and 15.0 g of sodium chloride, and grind them evenly in an agate mortar for 90 min. Transfer the mixture to a crucible and place it in a muffle furnace. Heat at a rate of 5 °C / min and hold at 600 °C for 5 h. After the reaction is complete, remove the product, centrifuge and wash it several times, and then dry it in an oven at 60 °C for 6 h.

[0046] Sodium alginate was completely dissolved in deionized water using a thermostatic magnetic stirrer at 0 °C for 8 h. 1.0 g of porous g-C3N4 and 2.0 g of pyrrole were then added and stirred at the same temperature to ensure uniform dispersion of the pyrrole and porous g-C3N4.

[0047] The melamine foam impregnated with the above homogeneous solution was cross-linked by immersing it in a 0.02 g / mL calcium chloride solution for 3 h. The cross-linked melamine foam was then oxidized by immersing it in a 2 mol / L FeCl3·6H2O solution for 8 h. This yielded a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability.

[0048] like Figure 5 As shown, the evaporator mainly consists of the micron-scale macroporous structure of the sponge itself and the sheet structure formed by the in-situ cross-linking of sodium alginate. This sheet structure divides the macropores of the sponge into segments, forming a more diverse pore structure. Carbon nitride and polypyrrole are distributed on the surface of the sheets formed by the sponge skeleton and sodium alginate.

[0049] This evaporator uses sodium alginate hydrogel as a matrix, which not only creates a highly efficient water transport channel but also provides excellent thermal management capabilities. In Fe... 3+ Under the influence of light, the hydrogel forms a unique "eggshell" fragmented structure, further enhancing capillary forces and optimizing the water transport mechanism. The Z-shaped heterojunction structure formed after oxidation successfully integrates photocatalytic and photothermal functions: on the one hand, it utilizes the temperature gradient and gravity within the hydrogel to achieve ion exchange; on the other hand, under light irradiation, the Z-shaped heterojunction constructed from PPy-CN can generate superoxide radicals (·O2). -) It reacts with hydroxyl radicals (·OH) to effectively degrade antibiotic wastewater.

[0050] This invention, based on a simple cross-linking oxidation strategy, rationally designs and constructs a Z-shaped heterojunction photocatalytic evaporator with excellent environmental adaptability. It targets antibiotic-contaminated and complex industrially polluted water bodies to achieve efficient solar evaporation and water purification. Melamine foam introduced during the preparation process serves as a structural support, significantly enhancing the device's mechanical strength while its intrinsic hydrophilic properties further optimize the water transport path, improving overall water delivery performance. The loaded hydrogel material possesses both good hydrophilicity and efficient thermal management capabilities, effectively suppressing heat loss and thus improving photothermal conversion efficiency. Simultaneously, based on the synergistic effect of the temperature gradient and gravity formed within the hydrogel, salt generated at the evaporation interface can be continuously discharged, maintaining the cleanliness and stability of the gas-liquid interface even during prolonged high-salinity seawater evaporation. More importantly, the Z-shaped heterojunction structure constructed in the composite material effectively promotes the synergistic effect of photothermal and photocatalytic processes, enhancing pollutant degradation efficiency. This type of hydrogel composite material has a simple preparation process, low cost, and environmental friendliness, demonstrating good industrialization prospects and broad application potential in the efficient treatment of recalcitrant antibiotic wastewater.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a Z-type heterojunction photocatalytic evaporator having excellent environmental adaptability, characterized by, The method comprises the following steps: Step 1: Put the melamine powder and sodium chloride into a mortar and grind them to mix uniformly; Step 2: Put the mixed medicine into a covered crucible and place it in a muffle furnace for reaction; Step 3: Take out the reaction product, wash it with water, centrifuge and dry it to obtain porous g-C3N4; Step 4: Put sodium alginate into water and stir under constant temperature and magnetic stirring until it is fully dissolved to form a uniform transparent solution; Step 5: Add pyrrole monomer Py and the porous g-C3N4 into the above uniform transparent solution in sequence, and continue to mix them by using a constant temperature magnetic stirrer to prepare a homogeneous slurry; Step 6: Soak the melamine foam cut in advance into the homogeneous slurry, and transfer it to a CaCl2 solution for the first step of cross-linking fixation; Step 7: After the calcium ion cross-linking treatment, the sample is further placed in a FeCl3·6H2O solution for treatment, and finally an excellent environment-applicable Z-type heterojunction photocatalytic evaporator is obtained.

2. The method for preparing a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability according to claim 1, characterized in that, In step 1, the mass ratio of melamine powder to sodium chloride is 3:1-1:3, and the grinding time is 30-90 min.

3. The method of claim 1, wherein the Z-type heterojunction photocatalytic evaporator having excellent environmental adaptability is prepared by the steps of: (a) preparing a Z-type heterojunction photocatalytic evaporator by mixing a photocatalytic material, a metal material, and a polymer material; and (b) coating a protective layer on the Z-type heterojunction photocatalytic evaporator. In step 2, the heating rate of the muffle furnace reaction is 1-5 ℃ / min, the holding temperature is 400-600 ℃, and the reaction time is 1-5 h.

4. The method of claim 1, wherein the Z-type heterojunction photocatalytic evaporator having excellent environmental adaptability is prepared by the steps of: In step 3, the drying reaction time is 6 h, and the drying temperature is 60 ℃.

5. The method for preparing a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability according to claim 1, characterized in that, In step 4, the sodium alginate is a byproduct obtained after extracting iodine and mannitol from kelp or sargassum of brown algae; In step 4, the constant temperature magnetic stirrer has a holding temperature of 25 ℃ and a holding time of 2-15 h.

6. The method for preparing a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability according to claim 1, characterized in that, In step 5, the mass of the porous g-C3N4 is 0.01-0.2 g / mL; the concentration of the Py-dissolved solution is 0.02-0.2 g / mL, the constant temperature magnetic stirrer has a holding temperature of 0 ℃, and the stirring time is 1-3 h.

7. The method for preparing a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability according to claim 1, characterized in that, In step 6, the concentration of the CaCl2-dissolved solution is 0.02 g / mL, the constant temperature magnetic stirrer has a holding temperature of 0 ℃, and the holding time is 0.5 h.

8. The method for preparing a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability according to claim 7, characterized in that, In step 6, the size of the melamine foam is 2 cm×2 cm×3 cm; In Step 6, Ca 2+ The crosslinking time is 1-3 h.

9. The method for preparing a Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability according to claim 1, characterized in that, In step 7, the concentration of the FeCl3·6H2O solution is 2 mol / L, and the oxidation time is 2-8 h.

10. A Z-type heterojunction photocatalytic evaporator with excellent environmental adaptability prepared based on the method according to any one of claims 1-9, characterized in that, The evaporator comprises the micron-sized large pore structure of the sponge itself and the lamellar structure formed after the in-situ cross-linking of sodium alginate, the lamellar structure divides the large pores of the sponge, forming a more diverse pore structure, and the carbon nitride and polypyrrole are distributed on the lamellar surface formed by the sponge skeleton and the sodium alginate; The evaporator takes sodium alginate hydrogel as the matrix, and under the action of Fe 3+ The hydrogel forms a unique "eggshell" broken structure, and the Z-type heterojunction structure formed after oxidation treatment successfully integrates the dual functions of photocatalysis and photothermal. The temperature gradient formed inside the hydrogel and the effect of gravity realize ion exchange; under light, the Z-type heterojunction constructed by PPy-CN produces superoxide free radicals (·O2 -) and hydroxyl radicals (·OH) for degrading antibiotic wastewater.

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