Degradable microalgae-based asymmetric hydrogel interface photo-thermal evaporator and preparation method and application thereof

Abstract

The invention discloses a degradable microalgae-based asymmetric hydrogel interface photo-thermal evaporator and a preparation method and application thereof, and belongs to the technical field of water treatment.The degradable microalgae-based asymmetric hydrogel interface photo-thermal evaporator comprises microalgae-PVA hydrogel and a photo-thermal material loaded on the microalgae-PVA hydrogel; wherein the microalgae comprise at least one of chlorella, green algae, diatom and haematococcus pluvialis; the photo-thermal material is a carbon-supported semiconductor material synthesized on the basis of microalgae adsorbing metal salt and a derivative of the carbon-supported semiconductor material. The photo-thermal evaporator has an excellent pore structure, photo-thermal absorption capacity and mechanical property, and meanwhile has low evaporation enthalpy and high thermal conductivity, and the evaporation rate of the solar evaporator is remarkably increased through the characteristics. In addition, the prepared photo-thermal evaporator is mainly based on microalgae and has the advantages of being degradable, environmentally friendly, high in salt resistance and excellent in water purification capacity. Therefore, the evaporator has a wide application prospect in the fields of seawater desalination and sewage treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and in particular relates to a degradable microalgae-based asymmetric hydrogel interface photothermal evaporator, a preparation method thereof, and an application thereof. Background Art

[0002] Desalination, the extraction of fresh water from seawater, is considered a highly viable approach to alleviating the worldwide shortage of available water resources. Solar water evaporation, a method that uses solar energy to evaporate seawater to produce fresh water, has attracted widespread attention from researchers due to its energy efficiency and low reliance on infrastructure. However, this method has significant drawbacks. Primarily, the heat captured from sunlight is largely lost to the environment through diffusion before being transferred to water evaporation, resulting in extremely low solar energy utilization.

[0003] The principle of solar water evaporation based on interfacial heating is to use photothermal materials located at the water-air interface to convert the absorbed solar energy into heat and retain it at the water-air interface where evaporation occurs. Since almost all the heat is used to convert water molecules from liquid to gas, the waste of heat is greatly reduced, and this technology achieves extremely high utilization of solar energy. It can be seen that solar-driven interfacial water evaporation has broad application prospects in seawater desalination. In this context, the design of interfacial photothermal evaporator based on hydrogel provides a new idea for improving the evaporation efficiency at the interface. This type of evaporator is mainly composed of two parts: a hydrogel skeleton and a light absorber, but most of them use non-degradable raw materials, which not only increases the environmental burden, but also has complex processes; moreover, its photothermal absorption capacity needs to be improved.

[0004] Therefore, it is of great significance to develop a biodegradable green photothermal evaporator for solar seawater desalination technology. Summary of the Invention

[0005] To address the above technical issues, the present invention proposes a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator, its preparation method, and its application. This photothermal evaporator exhibits excellent pore structure, photothermal absorption capacity, and mechanical properties, along with low evaporation enthalpy and high thermal conductivity. These properties significantly enhance the evaporation rate of solar evaporators. Furthermore, the degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator prepared by the present invention is primarily based on microalgae and is biodegradable, environmentally friendly, highly salt-tolerant, and possesses excellent water purification capabilities. Therefore, this evaporator has broad application prospects in seawater desalination and wastewater treatment.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention:

[0008] A degradable microalgae-based asymmetric hydrogel interface photothermal evaporator, comprising a microalgae-PVA hydrogel and a photothermal material loaded on the microalgae-PVA hydrogel;

[0009] Wherein, the microalgae include at least one of Chlorella, Green Algae, Diatom or Haematococcus pluvialis;

[0010] The photothermal material is a carbon-supported semiconductor material and its derivatives synthesized based on microalgae adsorbing metal salts.

[0011] Beneficial Effects: Microalgae possess functional groups such as -OH, -COOH, and -NH2. This invention utilizes them as a raw material substrate, crosslinking them with PVA through hydrogen bonds to form a three-dimensional network structure. Furthermore, the strong adsorption capacity of microalgae is utilized to adsorb metal salts to synthesize semiconductor materials and their derivatives with photothermal properties. The two are synergistically prepared to produce a lightweight, porous, and environmentally friendly biodegradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator. The evaporator's unique pore structure not only guides the rapid transport of water within the hydrogel but also prevents salt accumulation on the surface, providing strong support for a continuous and stable solar steam generation process. Furthermore, the evaporator exhibits high salt tolerance, excellent mechanical properties, and a lower enthalpy of evaporation, effectively increasing the evaporation rate and extending the service life of the solar evaporator. Therefore, the biodegradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator prepared by this invention has broad application prospects in seawater desalination and wastewater purification.

[0012] Optionally, the metal salt includes at least one of a copper salt, a molybdenum salt, a titanium salt or a manganese salt.

[0013] The second technical solution of the present invention:

[0014] A method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator comprises the following steps:

[0015] The microalgae are added to a PVA aqueous solution and heated and stirred to obtain a precursor solution, a pore-forming agent is added to the precursor solution, and then the solution is freeze-thawed, thawed, and soaked in a solvent in sequence to prepare a microalgae-PVA hydrogel;

[0016] The photothermal material is deposited on the surface of the microalgae-PVA hydrogel by suction filtration to prepare the degradable microalgae-based asymmetric hydrogel interface photothermal evaporator.

[0017] Optionally, the mass ratio of the microalgae to the PVA in the PVA aqueous solution is (6-9):(1-4); preferably 9:1, 8:2, 7:3 and 6:4.

[0018] Furthermore, the mass fraction of the PVA aqueous solution is 1-15wt%.

[0019] Optionally, the temperature during the heating and stirring process is 50-110°C.

[0020] Optionally, the mass ratio of the pore-forming agent to the solute in the precursor solution is (2.5-20):1, preferably 2.5:1, 5:1, 10:1, 15:1 and 20:1. The solute in the precursor solution is the sum of microalgae and PVA.

[0021] Furthermore, the pore-forming agent is at least one of edible white sugar, sugar cubes, sodium chloride or sodium carbonate.

[0022] Optionally, the freeze-thaw temperature is -20°C, the freeze-thaw time is 1-5 hours, and the thawing time is 1-5 hours.

[0023] Optionally, the preparation process of the photothermal material is:

[0024] The photothermal material is prepared by calcining or hydrothermally synthesizing the microalgae adsorbed with the metal salt.

[0025] Furthermore, the mass ratio of the microalgae to the metal salt in the microalgae adsorbed with the metal salt is 1-3:1-6.

[0026] Furthermore, the calcination conditions are: 1-5°C min -1 Heating rate: heat to 500-800℃ and keep at this temperature for 1-3h.

[0027] Furthermore, the conditions of the hydrothermal synthesis are: hydrothermal reaction at 100-300° C. for 5-24 hours.

[0028] The third technical solution of the present invention:

[0029] The application of the above-mentioned degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator in seawater desalination and wastewater purification.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] (1) Green and degradable: From the perspective of raw materials, microalgae have many advantages, such as abundant sources, low cost, and biodegradability, making them an ideal green evaporator material. From the perspective of function, microalgae have rich functional groups. The present invention discloses a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator composed of a microalgae-based hydrogel and a photothermal material synthesized based on microalgae loaded on the hydrogel. The hydrogel prepared by this method has the advantages of high porosity and light weight, and the entire preparation process is simple to operate and highly reproducible. In addition, the raw materials are mainly microalgae, which is green and environmentally friendly.

[0032] (2) Efficient evaporation: The microalgae-based asymmetric hydrogel interfacial photothermal evaporator prepared by the present invention has excellent photothermal conversion efficiency. Under sunlight, its temperature can reach up to 41.6°C. In addition, the evaporator prepared by the present invention not only has a low evaporation enthalpy and high thermal conductivity, which greatly improves the solar evaporation rate, but also has excellent salt tolerance and water purification capabilities. These characteristics enable the evaporator to operate stably for a long time, which can not only achieve efficient seawater desalination, but also effectively treat sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 This is a process flow chart of a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator prepared in accordance with an embodiment of the present invention;

[0035] Figure 2 The microalgae-based asymmetric hydrogel interface photothermal evaporator (Chlorella@MoS2 / C hydrogel) prepared in Example 1 was used at 1 kW m -2 Infrared thermal imaging images at 0min, 6min, 12min, 18min, 24min, and 30min under different light intensities;

[0036] Figure 3 The porous Chlorella hydrogel prepared in step (1) of Example 1, the Chlorella@MoS2 / C hydrogel prepared in steps (1) to (3) of Example 1, the PVA hydrogel prepared in Comparative Example 1, the pure Chlorella hydrogel prepared in Comparative Example 2 and deionized water were heated at 1 kWm -2 Comparison of evaporation rates after 0.5h of irradiation at different light intensities;

[0037] Figure 4 This is a comparison chart of the vaporization enthalpy of the porous Chlorella hydrogel prepared in step (1) of Example 1, the Chlorella@MoS2 / C hydrogel prepared in steps (1) to (3) of Example 1, the PVA hydrogel prepared in Comparative Example 1, the pure Chlorella hydrogel prepared in Comparative Example 2, and deionized water;

[0038] Figure 5 The Chlorella@MoS2 / C hydrogel prepared in Example 1 was heated to 1 kWm -2 Surface dissolution process of 0.5g salt under different light intensity;

[0039] Figure 6The UV-visible absorption spectra of the Chlorella@MoS2 / C hydrogel prepared in Example 1 before and after purification of methylene blue (MB) in industrial wastewater are shown. The inset is an optical photograph of MB before and after purification.

[0040] Figure 7 This is a physical picture of the Chlorella@MoS2 / C hydrogel prepared in Example 1;

[0041] Figure 8 This figure shows the effect of different mass ratios of microalgae (Ch) and PVA in PVA aqueous solution on the mechanical properties of the final prepared degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator;

[0042] Figure 9 This figure shows the effect of different mass ratios of pore-forming agent and solute in the precursor solution on the compressive mechanical properties of the final prepared degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator.

[0043] Figure 10 This is a comparison chart of the evaporation rate of the final prepared degradable microalgae-based asymmetric hydrogel interface photothermal evaporator with different addition amounts of photothermal material (MoS2 / C). DETAILED DESCRIPTION

[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0045] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0046] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0047] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0048] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0049] An embodiment of the present invention provides a degradable microalgae-based asymmetric hydrogel interface photothermal evaporator material, comprising a microalgae-PVA hydrogel and a photothermal material loaded on the microalgae-PVA hydrogel.

[0050] In some optional embodiments, the microalgae-PVA hydrogel is a three-dimensional network hydrogel structure formed by cross-linking microalgae rich in functional groups such as -COOH and -NH2 with -OH of PVA through hydrogen bonds and other interactions.

[0051] In some optional embodiments, the microalgae include at least one of Chlorella, Green Algae, Diatoms, and Haematococcus pluvialis.

[0052] In some optional embodiments, the photothermal material is based on the special microstructure of microalgae, and utilizes its functional groups such as hydroxyl groups to have a strong adsorption capacity for metals, adsorbs metal salts such as copper salts, molybdenum salts, titanium salts or manganese salts, and synthesizes carbon-supported semiconductor materials (MoS2, Ti2O3, CuO, TiN or MnO2) and their derivatives with photothermal properties.

[0053] The embodiment of the present invention discloses a method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator, comprising the following steps:

[0054] Step 1: PVA is dissolved in deionized water, heated and stirred to prepare a PVA aqueous solution, and then microalgae are added to the above solution, stirred and ultrasonicated to obtain a precursor solution;

[0055] Step 2: Add a certain amount of pore-forming agent to the precursor solution, mix well, pour into a mold, freeze and thaw, and use solvent soaking and washing to remove the pore-forming agent in the gel to obtain a lightweight and porous microalgae-PVA hydrogel;

[0056] Step 3: Dissolve the photothermal material powder synthesized by microalgae in deionized water, disperse it ultrasonically, and then filter it to deposit the photothermal material powder on the surface of the microalgae-PVA hydrogel matrix to obtain an asymmetric hydrogel photothermal conversion material.

[0057] In some optional embodiments, the mass fraction of the PVA aqueous solution prepared in step 1 is 1-15 wt %; the heating and stirring temperature is 50-110° C.; and the mass ratio of microalgae to PVA in the PVA aqueous solution is 9:1, 8:2, 7:3, and 6:4.

[0058] In some optional embodiments, the pore-forming agent in step 2 comprises at least one of edible white sugar, sugar cubes, sodium chloride or sodium carbonate; the mass ratio of the pore-forming agent to the solute in the precursor solution is 2.5:1, 5:1, 10:1, 15:1 and 20:1; the freezing temperature during the freeze-thaw process is -20°C, the freezing time is 1-5 hours, and the thawing time is 1-5 hours; and the solvent immersion washing time is 12-24 hours.

[0059] In some optional embodiments, the photothermal material in step 3 is prepared by using microalgae to adsorb metal salts, followed by calcination or hydrothermal synthesis; wherein the mass ratio of microalgae to metal salts is 1-3:1-6. Further, the calcination conditions are: 1-5°C min -1 Heating rate: heat to 500-800℃ and keep at this temperature for 1-3h.

[0060] In some optional embodiments, the amount of photothermal material added in step 3 is 0 g, 0.005 g, 0.01 g, 0.03 g, and 0.05 g, which are respectively dissolved in 500 mL of deionized water and then filtered onto the microalgae-PVA hydrogel.

[0061] In addition, the present invention also discloses the application of the above-mentioned degradable microalgae-based asymmetric hydrogel interface photothermal evaporator material in seawater desalination and wastewater purification.

[0062] The technical solution of the present invention is further illustrated by the following examples.

[0063] Example 1

[0064] like Figure 1 As shown, a method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator comprises the following steps:

[0065] (1) PVA was dissolved in deionized water, heated and stirred at 95°C to prepare a 10 wt% PVA aqueous solution. Chlorella vulgaris was added to the PVA aqueous solution (the mass ratio of Chlorella vulgaris to PVA was 7:3), mechanically stirred for 30 min, and ultrasonicated for 60 min to obtain a precursor solution. Edible white sugar granules were added to the precursor solution (the mass ratio of edible white sugar granules to the solute in the precursor solution was 5:1), mechanically stirred, poured into a mold, and frozen at -20°C for 3 h. After thawing for 1 h, it was washed with deionized water for 24 h until the gel floated on the water surface to obtain a lightweight porous microalgae-PVA hydrogel (porous Chlorella vulgaris hydrogel).

[0066] (2) The protein core of Chlorella vulgaris adsorbed with phosphomolybdic acid was placed in a tube furnace and heated at 5 °C min under H2 / Ar atmosphere. -1 The temperature was raised to 600 °C at a heating rate of 1000 °C and calcined for 3 h to obtain MoS2 / C powder (photothermal properties semiconductor material).

[0067] The preparation process of Chlorella adsorbing phosphomolybdic acid is as follows:

[0068] 0.2 g of Chlorella pyrenoidosa and 0.5 g of phosphomolybdic acid were added to 20 mL of deionized water and stirred continuously for 24 h (280 rmin -1 ) to form a uniform green solution; then centrifuged (2000 rmin -1 ), centrifuge 3 times (5 min- 1 ) to obtain Chlorella adsorbed with phosphomolybdic acid.

[0069] (3) 0.01 g of MoS2 / C powder was dispersed in 500 mL of deionized water and ultrasonically dispersed to make it uniform. Finally, MoS2 / C was deposited on the surface of the microalgae-based hydrogel matrix by filtration to obtain a microalgae-based asymmetric hydrogel interface photothermal evaporator (Chlorella vulgaris@MoS2 / C hydrogel).

[0070] Comparative Example 1

[0071] The preparation process of PVA hydrogel is as follows:

[0072] PVA was dissolved in deionized water, heated and stirred at 95° C. to prepare a 10 wt % PVA aqueous solution, i.e., a precursor solution, which was then poured into a mold, frozen for 3 h, and thawed.

[0073] Comparative Example 2

[0074] The preparation process of pure Chlorella hydrogel is as follows:

[0075] PVA was dissolved in deionized water and heated with stirring at 95°C to prepare a 10 wt% PVA aqueous solution. Chlorella pyrenoidosa was added to the PVA aqueous solution (the mass ratio of Chlorella pyrenoidosa to PVA in the PVA aqueous solution was 7:3), mechanically stirred for 30 minutes, and ultrasonicated for 60 minutes to obtain a precursor solution, which was poured into a mold, frozen for 3 hours, and then thawed.

[0076] Figure 2 The microalgae-based asymmetric hydrogel interface photothermal evaporator (Chlorella@MoS2 / C hydrogel) prepared in Example 1 was used at 1 kW m -2 Infrared thermal imaging images at 0min, 6min, 12min, 18min, 24min, and 30min under different light intensity; Figure 2It can be seen that the Chlorella@MoS2 / C hydrogel (i.e., microalgae-based asymmetric hydrogel interface photothermal evaporator) prepared in Example 1 of the present invention has a thermal conductivity of 1 kWm -2 The temperature change under light intensity can rapidly change by 22.3℃ within 0.5h, and the maximum temperature can reach 41.6℃, indicating that the evaporator has excellent light-to-heat conversion performance.

[0077] Figure 3 The porous Chlorella hydrogel prepared in step (1) of Example 1, the Chlorella@MoS2 / C hydrogel prepared in steps (1) to (3) of Example 1, the PVA hydrogel prepared in Comparative Example 1, the pure Chlorella hydrogel prepared in Comparative Example 2 and deionized water were heated at 1 kWm -2 Comparison of evaporation rates under different light intensities for 0.5h; Figure 3 It can be seen that under the same lighting conditions, the evaporation rates of different materials vary significantly, among which Chlorella@MoS2 / C hydrogel performs best, with an evaporation rate of up to about 3.4 kg·m -2 ·h -1 The results demonstrate that the introduction of a porous structure (e.g., porous Chlorella hydrogel) significantly improves the evaporation rate, likely due to the increased effective surface area for water transport and evaporation. Furthermore, Example 1 of the present invention, incorporating MoS2 / C into Chlorella hydrogel (Chlorella@MoS2 / C hydrogel), further enhances the evaporation rate, demonstrating that MoS2 / C possesses excellent photothermal conversion capabilities and can more effectively utilize light energy to promote water evaporation.

[0078] Figure 4 This is a comparison chart of the evaporation enthalpy of the porous Chlorella hydrogel prepared in step (1) of Example 1, the Chlorella@MoS2 / C hydrogel prepared in step (3) of Example 1, the PVA hydrogel prepared in Comparative Example 1, the pure Chlorella hydrogel prepared in Comparative Example 2, and deionized water. As can be seen from the figure, the Chlorella@MoS2 / C hydrogel prepared in the present invention has a lower evaporation enthalpy, which is about 1400 J g -1 The evaporation enthalpy of pure water under the same conditions is 2460 Jg -1 This demonstrates that the Chlorella@MoS2 / C hydrogel prepared in this invention significantly reduces the energy required for water evaporation (evaporation enthalpy) through efficient photothermal conversion, unique asymmetric structural design, and regulation of interfacial water behavior, thereby improving the overall efficiency of solar-driven evaporation. This provides a solid experimental basis and broad application prospects for its application in the field of efficient, energy-saving, and sustainable water resource treatment and utilization technology.

[0079] Figure 5The Chlorella@MoS2 / C hydrogel prepared in Example 1 was heated to 1 kWm -2 The surface dissolution process of 0.5g salt under light intensity is shown; it proves the desalination performance of the Chlorella@MoS2 / C hydrogel prepared by the present invention. 2 0.5 g of solid sodium chloride particles were deposited on the surface of the evaporator. After about 30 minutes, the sodium chloride particles on the surface completely disappeared, indicating that the evaporator has a high salt resistance.

[0080] Figure 6 The UV-visible absorption spectra of the Chlorella@MoS2 / C hydrogel prepared in Example 1 before and after purification of methylene blue (MB) in industrial wastewater are shown. The inset is an optical photograph of MB before and after purification. This demonstrates the ability of the Chlorella@MoS2 / C hydrogel to purify industrial wastewater. The UV-visible absorption spectrum of MB shows that the characteristic peak of MB disappears after purification, indicating that this evaporator has broad application prospects in wastewater treatment.

[0081] Figure 7 This is a physical picture of the lightweight Chlorella@MoS2 / C hydrogel prepared in Example 1.

[0082] Based on Example 1, the following series of experiments were conducted by controlling a single variable to prepare microalgae-based asymmetric hydrogel interfacial photothermal evaporators:

[0083] 1. Compared with Example 1, only the mass ratio of microalgae (Ch) to PVA in the PVA aqueous solution was changed: 9:1, 8:2 and 6:4;

[0084] 2. Compared with Example 1, only the mass ratio of the pore-forming agent to the solute in the precursor solution was changed: 2.5:1, 10:1, 15:1 and 20:1;

[0085] 3. Compared with Example 1, only the addition amount of the photothermal material (MoS2 / C) was changed: 0g, 0.005g, 0.03g, 0.05g.

[0086] Figure 8 This figure shows the influence of different mass ratios of microalgae (Ch) and PVA in PVA aqueous solution on the mechanical properties of the finally prepared degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator. It can be seen from the figure that when the ratio of microalgae to PVA is 7:3, the mechanical properties are optimal.

[0087] Figure 9This figure shows the influence of different mass ratios of pore-forming agent (edible white sugar) and solute in the precursor solution on the compressive mechanical properties of the finally prepared degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator. It can be seen from the figure that when the ratio of pore-forming agent to precursor solution solute is 5:1, the mechanical properties are optimal, reaching a maximum compressive strain of 80%.

[0088] Figure 10 The evaporation rate comparison chart of the final prepared biodegradable microalgae-based asymmetric hydrogel interface photothermal evaporator with different addition amounts of photothermal material (MoS2 / C) is shown in the figure. It can be seen from the figure that when the addition amount of photothermal material is 0.01g, the evaporation rate reaches a threshold of 3.4kg m -2 h -1 .

[0089] Example 2

[0090] A method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator comprises the following steps:

[0091] (1) PVA was dissolved in deionized water, heated and stirred at 95°C to prepare a 10 wt% PVA aqueous solution. Chlorella vulgaris was added to the PVA aqueous solution (the mass ratio of Chlorella vulgaris to PVA in the PVA aqueous solution was 7:3), mechanically stirred for 30 min, and ultrasonicated for 60 min to obtain a precursor solution. Edible white sugar particles were added to the precursor solution (the mass ratio of edible white sugar particles to the precursor solute was 10:1), mechanically stirred, poured into a mold, and frozen at -20°C for 3 h. After thawing for 1 h, the solution was washed with deionized water several times until the gel floated on the water surface, thereby obtaining a lightweight and porous microalgae-based hydrogel.

[0092] (2) The copper nitrate-adsorbed Chlorella vulgaris was hydrothermally reacted at 150°C for 20 h and further calcined at 500°C for 2 h under a nitrogen atmosphere to obtain copper oxide / carbon powder.

[0093] The preparation process of pyrenoid chlorella adsorbing copper nitrate is as follows:

[0094] 0.2 g of Chlorella pyrenoidosa and 0.5 g of copper nitrate were added to 20 mL of deionized water and stirred continuously for 24 h (280 rmin -1 ) to form a uniform green solution; then centrifuged (2000 r min -1 ), centrifuge 3 times (5 min each -1 ) to obtain Chlorella with copper nitrate.

[0095] (3) 0.01 g of copper oxide / carbon powder was dispersed in 400 mL of deionized water and ultrasonically dispersed to make it uniform; finally, copper oxide / carbon was deposited on the surface of the microalgae-based hydrogel matrix by filtration to obtain a microalgae-based composite hydrogel interface photothermal evaporator.

[0096] Example 3

[0097] A method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator comprises the following steps:

[0098] (1) PVA was dissolved in deionized water, heated and stirred at 95°C to prepare a 10 wt% PVA aqueous solution. Haematococcus pluvialis was added to the PVA aqueous solution (the mass ratio of Chlorella pluvialis to PVA in the PVA aqueous solution was 6:4), mechanically stirred for 30 min, and ultrasonicated for 60 min to obtain a precursor solution. Sodium carbonate was added to the precursor solution (the mass ratio of sodium carbonate to the precursor solution solute was 2.5:1), mechanically stirred, poured into a mold, and frozen at -20°C for 3 h. After thawing for 1 h, it was washed with deionized water several times until the gel floated on the water surface to obtain a lightweight and porous microalgae-based hydrogel.

[0099] (2) Same as step (2) in Example 1.

[0100] (3) 0.05 g of MoS2 / C powder material prepared in step (2) of Example 1 was placed in 500 mL of deionized water and uniformly dispersed by ultrasound. Finally, MoS2 / C was deposited on the surface of the microalgae-based hydrogel matrix by suction filtration to obtain a microalgae-based composite hydrogel interfacial photothermal evaporator.

[0101] Example 4

[0102] A method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator comprises the following steps:

[0103] (1) PVA was dissolved in deionized water, heated and stirred at 95°C to prepare a 10 wt% PVA aqueous solution. Haematococcus pluvialis was added to the PVA aqueous solution (the mass ratio of Chlorella pluvialis to PVA in the PVA aqueous solution was 8:2), mechanically stirred for 30 minutes, and ultrasonicated for 60 minutes to obtain a precursor solution. Sodium chloride was added to the precursor solution (the mass ratio of sodium chloride to the precursor solution solute was 15:1), mechanically stirred, poured into a mold, and frozen at -20°C for 3 hours. After thawing for 1 hour, it was washed with deionized water several times until the gel floated on the water surface to obtain a lightweight and porous microalgae-based hydrogel.

[0104] (2) Same as step (2) in Example 1.

[0105] (3) 0.01 g of the MoS2 / C powder material prepared in step (2) of Example 1 was placed in 500 mL of deionized water and evenly dispersed by ultrasound. Finally, the MoS2 / C was deposited on the surface of the microalgae-based hydrogel matrix by suction filtration to obtain a microalgae-based composite hydrogel interfacial photothermal evaporator.

[0106] Example 5

[0107] A method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator comprises the following steps:

[0108] (1) PVA was dissolved in deionized water, heated and stirred at 95°C to prepare a 10 wt% PVA aqueous solution. Haematococcus pluvialis was added to the PVA aqueous solution (the mass ratio of Chlorella pluvialis to PVA in the PVA aqueous solution was 9:1), mechanically stirred for 30 min, and ultrasonicated for 60 min to obtain a precursor solution. Sugar cubes were added to the precursor solution (the mass ratio of sugar cubes to the precursor solution solute was 20:1), mechanically stirred, poured into a mold, and frozen at -20°C for 3 h. After thawing for 1 h, the solution was washed with deionized water several times until the gel floated on the water surface to obtain a lightweight and porous microalgae-based hydrogel.

[0109] (2) Same as step (2) in Example 1.

[0110] (3) 0.03 g of MoS2 / C powder material prepared in step (2) of Example 1 was placed in 500 mL of deionized water and evenly dispersed by ultrasound. Finally, MoS2 / C was deposited on the surface of the microalgae-based hydrogel matrix by suction filtration to obtain a microalgae-based composite hydrogel interfacial photothermal evaporator.

[0111] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator, characterized in that: It includes a microalgae-PVA hydrogel and a photothermal material loaded on the microalgae-PVA hydrogel; Wherein, the microalgae is selected from at least one of Chlorella, Green Algae, Diatom or Haematococcus pluvialis; The photothermal material is a carbon-supported semiconductor material and its derivatives synthesized based on microalgae adsorbing metal salts.

2. The degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator according to claim 1, characterized in that: The metal salt is selected from at least one of copper salt, molybdenum salt, titanium salt or manganese salt.

3. A method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator, characterized in that: The following steps are involved: The microalgae are added to a PVA aqueous solution and heated and stirred to obtain a precursor solution, a pore-forming agent is added to the precursor solution, and then the solution is freeze-thawed, thawed, and soaked in a solvent in sequence to prepare a microalgae-PVA hydrogel; The photothermal material is deposited on the surface of the microalgae-PVA hydrogel by suction filtration to prepare the degradable microalgae-based asymmetric hydrogel interface photothermal evaporator according to any one of claims 1 to 2.

4. The method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator according to claim 3, characterized in that: The mass ratio of the microalgae to the PVA in the PVA aqueous solution is (6-9): (1-4).

5. The method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator according to claim 3, characterized in that: The mass ratio of the pore-forming agent to the solute in the precursor solution is (2.5-20):

1.

6. The method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator according to claim 5, characterized in that: The pore-forming agent is selected from at least one of white sugar, sugar cubes, sodium chloride or sodium carbonate.

7. The method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator according to claim 3, characterized in that: The preparation process of the photothermal material is as follows: The photothermal material is prepared by calcining or hydrothermally synthesizing microalgae adsorbed with metal salts.

8. The method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator according to claim 7, characterized in that: The mass ratio of the microalgae to the metal salt in the microalgae adsorbed with the metal salt is 1-3:1-6.

9. The method for preparing a degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator according to claim 7, characterized in that: The calcination conditions are: 1-5 ° C min -1 Heating rate: heating to 500-800℃ and keeping at this temperature for 1-3h; Alternatively, the hydrothermal synthesis conditions are: hydrothermal reaction at 100-300° C. for 5-24 hours.

10. Use of the degradable microalgae-based asymmetric hydrogel interfacial photothermal evaporator according to any one of claims 1 to 2 in seawater desalination and wastewater purification.

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