A solar interface evaporator based on a full biomass raw material and a preparation method thereof

Abstract

The application discloses a solar interfacial evaporator based on full-biomass raw materials and a preparation method thereof. The method first utilizes gallnut insect galls, which are purified by dilute acid and loaded with transition metals, to prepare carbon-based photothermal materials through laser irradiation and carbonization. Meanwhile, cross-linkable alginate is obtained by alkali extraction and solvent precipitation purification from brown algae. Subsequently, the carbon-based photothermal materials are dispersed in the alginate solution to form a uniform and stable photothermal composite precursor through electrostatic adsorption and hydrogen bonding. Then, the precursor is blended with a pregelatinized starch solution, and after the alginate gel network is cross-linked and solidified by divalent cations, the starch phase is dissolved in warm water, thereby forming a hydrogel evaporator with a unique dual-mode through-pore structure. The obtained biomass-based hydrogel evaporator has a through-porous network, and the photothermal materials are stably embedded in the pore wall, which is suitable for the field of solar interfacial evaporation and has high light-heat conversion and interfacial water evaporation capacity.

Description

Technical Field

[0001] This invention belongs to the field of soft matter energy materials, specifically relating to a solar interface evaporator based on all biomass raw materials and its preparation method. Background Technology

[0002] Solar interfacial evaporation technology has attracted much attention due to its clean solar energy source, pollution-free operation, and lack of complex post-treatment requirements. This technology achieves efficient water purification through selective evaporation of liquids at the gas-liquid interface, avoiding the energy waste of traditional bulk heating. Current research focuses on developing high-performance photothermal conversion materials (such as polymer aerogels, carbon-based thin films, and composite materials) to improve evaporation efficiency. Key technologies focus on two main directions: first, enhancing photothermal conversion efficiency by optimizing light-absorbing and thermally conductive materials; and second, constructing porous structures to expand the gas-liquid interface contact area, promoting rapid vapor dissipation and suppressing heat loss. However, existing material systems still face challenges such as insufficient biocompatibility, unsustainable raw materials, or limited pore structure. Summary of the Invention

[0003] The first objective of this invention is to provide a method for preparing a solar interface evaporator based on all biomass raw materials.

[0004] A second objective of the present invention is to provide a solar interface evaporator based on all biomass raw materials prepared by the above-described preparation method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a solar interface evaporator based on all biomass raw materials, comprising the following steps:

[0007] (1) Preparation of carbon-based materials derived from gallnut galls: Dried gallnut galls were pulverized, washed and filtered after soaking in dilute acid solution. The resulting filter residue was immersed in a transition metal salt solution, ultrasonically treated, and the solid was separated by centrifugation. This solid was evenly spread on a quartz substrate in a laser reaction chamber, inert gas was introduced and the chamber was sealed, and carbonized by CO2 laser irradiation. The irradiated product was directly transferred to a crushing container, frozen and embrittled, and then circulated in a microfluidic homogenizer. The resulting homogenate was purified to remove impurities and finally dried to obtain carbon-based materials derived from gallnut galls. The transition metal salt was selected from CuSO4·5H2O and FeCl3·6H2O.

[0008] (2) Obtaining crosslinkable brown algae polysaccharides: Brown algae raw materials are subjected to gradient alkaline extraction to break down the cell wall structure and release polysaccharide components under alkaline conditions. Then, sodium salt solution is added to the system to convert the released polysaccharides into a soluble form. After filtering to remove residue, anhydrous ethanol is added to the solution containing soluble polysaccharides to induce polysaccharide precipitation by controlling the solvent polarity. The precipitate is collected by centrifugation and washed, and finally dried to obtain crosslinkable brown algae polysaccharide powder.

[0009] (3) Preparation of photothermal composite precursor based on crosslinkable brown algae polysaccharide: crosslinkable brown algae polysaccharide powder is dissolved in deionized water to form a biopolysaccharide solution, and then gall gall-derived carbon-based material is dispersed in the biopolysaccharide solution to prepare a photothermal composite precursor.

[0010] (4) Preparation of dual-mode pore gel based on crosslinkable brown algae polysaccharide and starch sacrificial template: The photothermal composite precursor obtained in step (3) was mixed with the pregelatinized starch solution at a volume ratio of 1:1. After vacuum degassing, the mixture was injected into a mold and a divalent cationic crosslinking agent was added to solidify the brown algae network. The gel was immersed in 50°C deionized water to dissolve the starch phase, forming a dual-mode pore structure with template-exfoliated main pores and in-situ self-assembled nanofiber network.

[0011] Preferably, in step (1), the frequency of the ultrasound is 40 kHz and the duration is 30 minutes.

[0012] Preferably, in step (1), the power density of the laser is 3.5 kW / cm². 2 The scanning speed is 20 mm / s.

[0013] Preferably, in step (1), the pressure of the microjet homogenizer is 180 MPa.

[0014] Preferably, in step (2), the brown algae is selected from either *Sargassum fusiforme* or *Sargassum fusiforme*.

[0015] Preferably, in step (3), the mass concentration of brown algae polysaccharide in the photothermal composite precursor is 3 wt%, and the mass concentration of carbon-based material is 2 wt%.

[0016] Preferably, in step (4), the starch is selected from cassava starch and corn starch.

[0017] Preferably, in step (4), the divalent cationic crosslinking agent is selected from CaCl2 and BaCl2.

[0018] Preferably, in a second aspect, the present invention also provides a solar interface evaporator based on all biomass raw materials prepared by the above preparation method.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) This invention provides a novel approach combining brown algae-derived gel with solar clean energy. The gall-derived carbon-based material from gallnut larvae, used as a photothermal conversion material, exhibits a broad solar absorption spectrum and high photothermal conversion efficiency after transition metal modification and laser carbonization.

[0021] 2) The brown algae-derived hydrogel used in this invention has a dual-mode through-pore structure, good structural stability and efficient water transport performance. Attached Figure Description

[0022] Figure 1 A flowchart for preparing carbon-based materials derived from galls of the gall worm.

[0023] Figure 2 A flowchart for obtaining cross-linkable brown algal polysaccharides from brown algae.

[0024] Figure 3 A flowchart for preparing a dual-mode porous gel.

[0025] Figure 4 Scanning electron microscope image of carbon-based material derived from galls of the gall worm.

[0026] Figure 5 This is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 1.

[0027] Figure 6 This is a photograph of the hydrogel with photothermal conversion capability in Example 1.

[0028] Figure 7 This is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 2.

[0029] Figure 8 This is a photograph of the hydrogel with photothermal conversion capability in Example 2.

[0030] Figure 9 This is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 3.

[0031] Figure 10 This is a photograph of the hydrogel with photothermal conversion capability in Example 3.

[0032] Figure 11 This is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 4.

[0033] Figure 12 This is a photograph of the hydrogel with photothermal conversion capability in Example 4.

[0034] Figure 13 This is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 5.

[0035] Figure 14 This is a photograph of the hydrogel with photothermal conversion capability in Example 5.

[0036] Figure 15 This is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 6.

[0037] Figure 16 This is a photograph of the hydrogel with photothermal conversion capability in Example 6.

[0038] Figure 17 This is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 7.

[0039] Figure 18 This is a photograph of the hydrogel with photothermal conversion capability in Example 7.

[0040] Figure 19 This is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 8.

[0041] Figure 20 This is a photograph of the hydrogel with photothermal conversion capability in Example 8. Detailed Implementation

[0042] To address the issue of low performance of photothermal conversion materials in existing solar interfacial evaporation technologies, this invention proposes a solar interfacial evaporator based on all biomass raw materials and its preparation method, which includes the following steps:

[0043] (1) Preparation of carbon-based materials derived from galls of Galla chinensis: such as Figure 1 As shown, dried gallnut galls were ground and pulverized, washed and filtered after soaking in dilute acid solution. The resulting filter residue was immersed in a transition metal salt solution, subjected to low-frequency ultrasonic treatment, and the solid was separated by centrifugation. This solid was evenly spread on a quartz substrate in a laser reaction chamber, inert gas was introduced and the chamber was sealed, and the surface of the solid was irradiated by a high-power laser beam to achieve carbonization. The irradiated product was directly transferred to a crushing container, frozen and embrittled with liquid nitrogen, and then circulated in a microfluidic homogenizer. The resulting homogenate was purified to remove impurities and finally freeze-dried to obtain gallnut gall-derived carbon-based materials.

[0044] (2) Obtaining cross-linkable brown algae polysaccharides: such as Figure 2 As shown, brown algae raw materials were subjected to gradient alkaline extraction to break down the cell wall structure and release polysaccharide components under alkaline conditions. Then, sodium salt solution was added to the system to convert the released polysaccharides into a soluble form. After filtering to remove residue, anhydrous ethanol was added to the solution containing soluble polysaccharides to induce polysaccharide precipitation by controlling the solvent polarity. The precipitate was collected by centrifugation and washed, and finally obtained crosslinkable brown algae polysaccharide powder by freeze drying.

[0045] (3) Preparation of photothermal composite precursors based on crosslinkable brown algae polysaccharides: such as Figure 3 As shown, crosslinkable brown algae polysaccharide powder is dissolved in deionized water to form a biopolysaccharide solution, and then gall gall-derived carbon-based material is dispersed in the biopolysaccharide solution to prepare a photothermal composite precursor. In the precursor, the surface of the photothermal material is coated with alginate molecules through electrostatic adsorption and hydrogen bonding to achieve uniform dispersion.

[0046] (4) Preparation of bimodal porous gels induced by sacrificial templates of crosslinkable brown algae polysaccharides and starch: such as Figure 3 As shown, the photothermal composite precursor obtained in step (3) is mixed with the pregelatinized starch solution at a volume ratio of 1:1, and after vacuum degassing, it is injected into a mold. A divalent cationic crosslinking agent is added to solidify the alginate network. The gel is then immersed in 50°C deionized water to dissolve the starch phase, forming a dual-mode pore structure with template-exfoliated main channels and in-situ self-assembled nanofiber networks.

[0047] In some embodiments, in step (1), the frequency of the ultrasound is 40 kHz and the duration is 30 minutes.

[0048] In some embodiments, in step (1), the laser power density is 3.5 kW / cm². 2 The scanning speed is 20 mm / s.

[0049] In some embodiments, in step (1), the pressure of the microjet homogenizer is 180 MPa.

[0050] In some embodiments, in step (2), the brown algae is selected from either *Sargassum fusiforme* or *Sargassum fusiforme*.

[0051] In some embodiments, in step (3), the mass concentration of brown algae polysaccharide in the photothermal composite precursor is 3 wt%, and the mass concentration of carbon-based material is 2 wt%.

[0052] In some embodiments, in step (4), the starch is selected from tapioca starch and corn starch.

[0053] In some embodiments, in step (4), the divalent cationic crosslinking agent is selected from CaCl2 and BaCl2.

[0054] This invention utilizes gall-derived carbon-based materials from gallnut insects as the core for photothermal conversion, achieving efficient photothermal conversion through transition metal salt modification and high-power laser irradiation. Simultaneously, a dual-mode interconnected pore structure is constructed using brown algae polysaccharides and starch: on one hand, macroscopic main channels are formed using a sacrificial template method to accelerate water transport; on the other hand, an in-situ self-assembled nanofiber network provides capillary force and vapor diffusion channels. This multi-level pore synergy significantly enhances water transport dynamics and vapor dissipation efficiency, while the all-biomass raw material system ensures the material's environmental friendliness and sustainability. Furthermore, the divalent cationic cross-linked alginate network endows the hydrogel with excellent mechanical stability, making this material promising for applications in high-efficiency solar desalination and wastewater treatment.

[0055] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0056] Example 1

[0057] (1) The dried gallnut galls were pulverized and passed through a 100-mesh sieve. They were then immersed in a 0.5 mol / L H₂SO₄ solution at a solid-liquid ratio of 1:10 (g / mL) for 12 hours at 25°C. After filtration, the residue was immersed in a 0.1 mol / L FeCl₃ solution (metal element: gallnut gall mass ratio = 1:30), sonicated at 40 kHz for 30 minutes, and centrifuged to obtain the solid. This solid was spread evenly on a 1 mm thick quartz substrate, and a N₂:Ar = 8:2 (v / v) mixed gas was introduced and sealed. Carbonization was then carried out using a CO₂ laser with a power density of 3.5 kW / cm². 2 The scanning speed was 20 mm / s. After being frozen in liquid nitrogen, the product was circulated five times in a 180 MPa microfluidic homogenizer, dialyzed to remove impurities, and then freeze-dried to obtain a carbon-based material. Its scanning electron microscope image is shown below. Figure 4 As shown.

[0058] (2) The dried Sargassum fusiforme raw material was pulverized using a high-speed pulverizer with a 60-mesh sieve, and the sieved powder was collected. The Sargassum fusiforme powder was mixed with 0.1 mol / L NaOH solution at a ratio of 1:10 (g / mL) and stirred at 80℃ for 2 hours. After coarse filtration, 10 wt% NaCl solution was added to the filtrate, and the mixture was centrifuged at 12000 rpm for 15 minutes. The supernatant was taken and 2 volumes of anhydrous ethanol were added dropwise. The precipitate was collected by centrifugation and freeze-dried to obtain brown algae polysaccharide powder.

[0059] (3) The brown algae polysaccharide powder and carbon-based materials were dispersed together in deionized water to prepare a mixed solution containing 3wt% brown algae polysaccharide and 2wt% carbon-based materials. The solution was homogenized at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0060] (4) The precursor was mixed with 1 wt% pregelatinized corn starch solution at a volume ratio of 1:1 and vacuum degassed for 10 minutes. After being injected into a mold, it was immersed in 0.5 mol / L CaCl2 solution for crosslinking for 3 hours, and then transferred to 50℃ deionized water for 24 hours to dissolve the starch, thus obtaining a dual-mode pore hydrogel.

[0061] When the obtained hydrogel is placed on water, the carbon-based material captures sunlight under sunlight and converts the captured sunlight into heat energy using high photothermal conversion efficiency, and evaporates the water in the pores on the surface of the hydrogel.

[0062] Figure 5 The image shown is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 1, which clearly shows the interconnected main channels and the nanofiber network on the pore walls.

[0063] Figure 6 The image shows a physical example of the hydrogel with photothermal conversion capability in Example 1. Its homogeneous black appearance indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0064] Example 2

[0065] (1) The dried gallnut galls were pulverized and passed through a 100-mesh sieve. They were then immersed in a 0.5 mol / L H₂SO₄ solution at a solid-liquid ratio of 1:10 (g / mL) for 12 hours at 25°C. After filtration, the residue was immersed in a 0.1 mol / L FeCl₃ solution (metal element: gallnut gall mass ratio = 1:30), sonicated at 40 kHz for 30 minutes, and centrifuged to obtain the solid. This solid was spread evenly on a 1 mm thick quartz substrate, and a N₂:Ar = 8:2 (v / v) mixed gas was introduced and sealed. Carbonization was then carried out using a CO₂ laser with a power density of 3.5 kW / cm². 2 The scanning speed was 20 mm / s. After being frozen in liquid nitrogen, the product was circulated five times in a 180 MPa microfluidic homogenizer, dialyzed to remove impurities, and then freeze-dried to obtain a carbon-based material. Its scanning electron microscope image is shown below. Figure 4 As shown.

[0066] (2) The dried *Ilex chinensis* raw material was pulverized using a high-speed pulverizer with a 60-mesh sieve, and the sieved powder was collected. The *Ilex chinensis* powder was mixed with 0.1 mol / L NaOH solution at a ratio of 1:10 (g / mL) and stirred at 80°C for 2 hours. After coarse filtration, 10 wt% NaCl solution was added to the filtrate, and the mixture was centrifuged at 12000 rpm for 15 minutes. The supernatant was collected, and two volumes of anhydrous ethanol were added dropwise. The precipitate was collected by centrifugation and freeze-dried to obtain brown algae polysaccharide powder.

[0067] (3) The brown algae polysaccharide powder and carbon-based materials were dispersed together in deionized water to prepare a mixed solution containing 3wt% brown algae polysaccharide and 2wt% carbon-based materials. The solution was homogenized at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0068] (4) The precursor was mixed with 1 wt% pregelatinized corn starch solution at a volume ratio of 1:1 and vacuum degassed for 10 minutes. After being injected into a mold, it was immersed in 0.5 mol / L CaCl2 solution for crosslinking for 3 hours, and then transferred to 50℃ deionized water for 24 hours to dissolve the starch, thus obtaining a dual-mode pore hydrogel.

[0069] When the obtained hydrogel is placed on water, the carbon-based material captures sunlight under sunlight and converts the captured sunlight into heat energy using high photothermal conversion efficiency, and evaporates the water in the pores on the surface of the hydrogel.

[0070] Figure 7 The image shown is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 2, which clearly shows the interconnected main channels and the nanofiber network on the pore walls.

[0071] Figure 8 The image shows a physical example of the hydrogel with photothermal conversion capability in Example 2. Its homogeneous black appearance indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0072] Example 3

[0073] (1) The dried gallnut galls were pulverized and passed through a 100-mesh sieve. They were then immersed in a 0.5 mol / L H₂SO₄ solution at a solid-liquid ratio of 1:10 (g / mL) for 12 hours at 25°C. After filtration, the residue was immersed in a 0.1 mol / L FeCl₃ solution (metal element: gallnut gall mass ratio = 1:30), sonicated at 40 kHz for 30 minutes, and centrifuged to obtain the solid. This solid was spread evenly on a 1 mm thick quartz substrate, and a N₂:Ar = 8:2 (v / v) mixed gas was introduced and sealed. Carbonization was then carried out using a CO₂ laser with a power density of 3.5 kW / cm². 2 The scanning speed was 20 mm / s. After being frozen in liquid nitrogen, the product was circulated five times in a 180 MPa microfluidic homogenizer, dialyzed to remove impurities, and then freeze-dried to obtain a carbon-based material. Its scanning electron microscope image is shown below. Figure 4 As shown.

[0074] (2) The dried Sargassum fusiforme raw material was pulverized using a high-speed pulverizer with a 60-mesh sieve, and the sieved powder was collected. The Sargassum fusiforme powder was mixed with 0.1 mol / L NaOH solution at a ratio of 1:10 (g / mL) and stirred at 80°C for 2 hours. After coarse filtration, 10 wt% NaCl solution was added to the filtrate, and the mixture was centrifuged at 12000 rpm for 15 minutes. The supernatant was collected, and 2 volumes of anhydrous ethanol were added dropwise. The precipitate was collected by centrifugation and freeze-dried to obtain brown algae polysaccharide powder.

[0075] (3) The brown algae polysaccharide powder and carbon-based materials were dispersed together in deionized water to prepare a mixed solution containing 3wt% brown algae polysaccharide and 2wt% carbon-based materials. The solution was homogenized at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0076] (4) The precursor was mixed with 1 wt% pregelatinized cassava starch solution at a volume ratio of 1:1 and vacuum degassed for 10 minutes. After being injected into a mold, it was immersed in 0.5 mol / L CaCl2 solution for crosslinking for 3 hours, and then transferred to 50℃ deionized water for 24 hours to dissolve the starch, thus obtaining a dual-mode pore hydrogel.

[0077] When the obtained hydrogel is placed on water, the carbon-based material captures sunlight under sunlight and converts the captured sunlight into heat energy using high photothermal conversion efficiency, and evaporates the water in the pores on the surface of the hydrogel.

[0078] Figure 9 The image shown is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 3. It clearly shows the through-hole main channel and the nanofiber network on the pore wall, and the main channel can be found to be enlarged.

[0079] Figure 10 The image shows a physical example of the hydrogel with photothermal conversion capability in Example 3. Its homogeneous black appearance indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0080] Example 4

[0081] (1) The dried gallnut galls were pulverized and passed through a 100-mesh sieve. They were then immersed in a 0.5 mol / L H₂SO₄ solution at a solid-liquid ratio of 1:10 (g / mL) for 12 hours at 25°C. After filtration, the residue was immersed in a 0.1 mol / L FeCl₃ solution (metal element: gallnut gall mass ratio = 1:30), sonicated at 40 kHz for 30 minutes, and centrifuged to obtain the solid. This solid was spread evenly on a 1 mm thick quartz substrate, and a N₂:Ar = 8:2 (v / v) mixed gas was introduced and sealed. Carbonization was then carried out using a CO₂ laser with a power density of 3.5 kW / cm². 2 The scanning speed was 20 mm / s. After being frozen in liquid nitrogen, the product was circulated five times in a 180 MPa microfluidic homogenizer, dialyzed to remove impurities, and then freeze-dried to obtain a carbon-based material. Its scanning electron microscope image is shown below. Figure 4 As shown.

[0082] (2) The dried Sargassum fusiforme raw material was pulverized using a high-speed pulverizer with a 60-mesh sieve, and the sieved powder was collected. The Sargassum fusiforme powder was mixed with 0.1 mol / L NaOH solution at a ratio of 1:10 (g / mL) and stirred at 80°C for 2 hours. After coarse filtration, 10 wt% NaCl solution was added to the filtrate, and the mixture was centrifuged at 12000 rpm for 15 minutes. The supernatant was collected, and 2 volumes of anhydrous ethanol were added dropwise. The precipitate was collected by centrifugation and freeze-dried to obtain brown algae polysaccharide powder.

[0083] (3) The brown algae polysaccharide powder and carbon-based materials were dispersed together in deionized water to prepare a mixed solution containing 3wt% brown algae polysaccharide and 2wt% carbon-based materials. The solution was homogenized at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0084] (4) The precursor was mixed with 1 wt% pregelatinized corn starch solution at a volume ratio of 1:1 and vacuum degassed for 10 minutes. After being injected into a mold, it was immersed in 0.5 mol / L BaCl2 solution for crosslinking for 3 hours, and then transferred to 50℃ deionized water for 24 hours to dissolve the starch, thus obtaining a dual-mode pore hydrogel.

[0085] When the obtained hydrogel is placed on water, the carbon-based material captures sunlight under sunlight and converts the captured sunlight into heat energy using high photothermal conversion efficiency, and evaporates the water in the pores on the surface of the hydrogel.

[0086] Figure 11 The image shown is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 4, which clearly shows the interconnected main channels and the nanofiber network on the pore walls.

[0087] Figure 12 The image shows a physical example of the hydrogel with photothermal conversion capability in Example 4. Its homogeneous black appearance indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0088] Example 5

[0089] (1) The dried gallnut galls were pulverized and passed through a 100-mesh sieve. They were then immersed in a 0.5 mol / L H₂SO₄ solution at a solid-liquid ratio of 1:10 (g / mL) for 12 hours at 25°C. After filtration, the residue was immersed in a 0.1 mol / L CuSO₄ solution (metal element: gallnut gall mass ratio = 1:30), sonicated at 40 kHz for 30 minutes, and centrifuged to obtain the solid. This solid was spread evenly on a 1 mm thick quartz substrate, and a N₂:Ar = 8:2 (v / v) mixed gas was introduced and sealed. Carbonization was then carried out using a CO₂ laser with a power density of 3.5 kW / cm². 2 The scanning speed was 20 mm / s. After being frozen in liquid nitrogen, the product was circulated five times in a 180 MPa microfluidic homogenizer, dialyzed to remove impurities, and then freeze-dried to obtain a carbon-based material. Its scanning electron microscope image is shown below. Figure 4 As shown.

[0090] (2) The dried Sargassum fusiforme raw material was pulverized using a high-speed pulverizer with a 60-mesh sieve, and the sieved powder was collected. The Sargassum fusiforme powder was mixed with 0.1 mol / L NaOH solution at a ratio of 1:10 (g / mL) and stirred at 80°C for 2 hours. After coarse filtration, 10 wt% NaCl solution was added to the filtrate, and the mixture was centrifuged at 12000 rpm for 15 minutes. The supernatant was collected, and 2 volumes of anhydrous ethanol were added dropwise. The precipitate was collected by centrifugation and freeze-dried to obtain brown algae polysaccharide powder.

[0091] (3) The brown algae polysaccharide powder and carbon-based materials were dispersed together in deionized water to prepare a mixed solution containing 3wt% brown algae polysaccharide and 2wt% carbon-based materials. The solution was homogenized at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0092] (4) The precursor was mixed with 1 wt% pregelatinized corn starch solution at a volume ratio of 1:1 and vacuum degassed for 10 minutes. After being injected into a mold, it was immersed in 0.5 mol / L CaCl2 solution for crosslinking for 3 hours, and then transferred to 50℃ deionized water for 24 hours to dissolve the starch, thus obtaining a dual-mode pore hydrogel.

[0093] When the obtained hydrogel is placed on water, the carbon-based material captures sunlight under sunlight and converts the captured sunlight into heat energy using high photothermal conversion efficiency, and evaporates the water in the pores on the surface of the hydrogel.

[0094] Figure 13 The image shown is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 5, which clearly shows the interconnected main channels and the nanofiber network on the pore walls.

[0095] Figure 14 The image shows a physical picture of the hydrogel with photothermal conversion capability in Example 5. Its homogeneous black appearance indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0096] Example 6

[0097] (1) The dried gallnut galls were pulverized and passed through a 100-mesh sieve. They were then immersed in a 0.5 mol / L H₂SO₄ solution at a solid-liquid ratio of 1:10 (g / mL) for 12 hours at 25°C. After filtration, the residue was immersed in a 0.1 mol / L FeCl₃ solution (metal element: gallnut gall mass ratio = 1:30), sonicated at 40 kHz for 30 minutes, and centrifuged to obtain the solid. This solid was spread evenly on a 1 mm thick quartz substrate, and a N₂:Ar = 8:2 (v / v) mixed gas was introduced and sealed. Carbonization was then carried out using a CO₂ laser with a power density of 3.5 kW / cm². 2 The scanning speed was 20 mm / s. After being frozen in liquid nitrogen, the product was circulated five times in a 180 MPa microfluidic homogenizer, dialyzed to remove impurities, and then freeze-dried to obtain a carbon-based material. Its scanning electron microscope image is shown below. Figure 4 As shown.

[0098] (2) The dried Sargassum fusiforme raw material was pulverized using a high-speed pulverizer with a 60-mesh sieve, and the sieved powder was collected. The Sargassum fusiforme powder was mixed with 0.1 mol / L NaOH solution at a ratio of 1:10 (g / mL) and stirred at 80°C for 2 hours. After coarse filtration, 10 wt% NaCl solution was added to the filtrate, and the mixture was centrifuged at 12000 rpm for 15 minutes. The supernatant was collected, and 2 volumes of anhydrous ethanol were added dropwise. The precipitate was collected by centrifugation and freeze-dried to obtain brown algae polysaccharide powder.

[0099] (3) The brown algae polysaccharide powder and carbon-based materials were dispersed together in deionized water to prepare a mixed solution containing 3wt% brown algae polysaccharide and 2wt% carbon-based materials. The solution was homogenized at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0100] (4) The precursor was mixed with 6 wt% pregelatinized corn starch solution at a volume ratio of 1:1 and vacuum degassed for 10 minutes. After being injected into a mold, it was immersed in 0.5 mol / L CaCl2 solution for crosslinking for 3 hours, and then transferred to 50℃ deionized water for 24 hours to dissolve the starch, thus obtaining a dual-mode pore hydrogel.

[0101] When the obtained hydrogel is placed on water, the carbon-based material captures sunlight under sunlight and converts the captured sunlight into heat energy using high photothermal conversion efficiency, and evaporates the water in the pores on the surface of the hydrogel.

[0102] Figure 15 The image shown is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 6, which clearly shows the interconnected main channels and the nanofiber network on the pore walls.

[0103] Figure 16 The image shows a physical example of the hydrogel with photothermal conversion capability in Example 6. Its homogeneous black appearance indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0104] Example 7

[0105] (1) The dried gallnut galls were pulverized and passed through a 100-mesh sieve. They were then immersed in a 0.5 mol / L H₂SO₄ solution at a solid-liquid ratio of 1:10 (g / mL) for 12 hours at 25°C. After filtration, the residue was immersed in a 0.1 mol / L FeCl₃ solution (metal element: gallnut gall mass ratio = 1:30), sonicated at 40 kHz for 30 minutes, and centrifuged to obtain the solid. This solid was spread evenly on a 1 mm thick quartz substrate, and a N₂:Ar = 8:2 (v / v) mixed gas was introduced and sealed. Carbonization was then carried out using a CO₂ laser with a power density of 3.5 kW / cm². 2 The scanning speed was 20 mm / s. After being frozen in liquid nitrogen, the product was circulated five times in a 180 MPa microfluidic homogenizer, dialyzed to remove impurities, and then freeze-dried to obtain a carbon-based material. Its scanning electron microscope image is shown below. Figure 4 As shown.

[0106] (2) The dried Sargassum fusiforme raw material was pulverized using a high-speed pulverizer with a 60-mesh sieve, and the sieved powder was collected. The Sargassum fusiforme powder was mixed with 0.1 mol / L NaOH solution at a ratio of 1:10 (g / mL) and stirred at 80°C for 2 hours. After coarse filtration, 10 wt% NaCl solution was added to the filtrate, and the mixture was centrifuged at 12000 rpm for 15 minutes. The supernatant was collected, and 2 volumes of anhydrous ethanol were added dropwise. The precipitate was collected by centrifugation and freeze-dried to obtain brown algae polysaccharide powder.

[0107] (3) The brown algae polysaccharide powder and carbon-based materials were dispersed together in deionized water to prepare a mixed solution containing 4 wt% brown algae polysaccharide and 2 wt% carbon-based materials. The solution was homogenized at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0108] (4) The precursor was mixed with 1 wt% pregelatinized corn starch solution at a volume ratio of 1:1 and vacuum degassed for 10 minutes. After being injected into a mold, it was immersed in 0.5 mol / L CaCl2 solution for crosslinking for 3 hours, and then transferred to 50℃ deionized water for 24 hours to dissolve the starch, thus obtaining a dual-mode pore hydrogel.

[0109] When the obtained hydrogel is placed on water, the carbon-based material captures sunlight under sunlight and converts the captured sunlight into heat energy using high photothermal conversion efficiency, and evaporates the water in the pores on the surface of the hydrogel.

[0110] Figure 17 The image shown is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 7, which clearly shows the through-hole main channels and the nanofiber network on the pore walls. Compared with other examples, the number of main channels is reduced.

[0111] Figure 18 The image shows a physical sample of the hydrogel with photothermal conversion capability in Example 7. Its homogeneous black appearance indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0112] Example 8

[0113] (1) The dried gallnut galls were pulverized and passed through a 100-mesh sieve. They were then immersed in a 0.5 mol / L H₂SO₄ solution at a solid-liquid ratio of 1:10 (g / mL) for 12 hours at 25°C. After filtration, the residue was immersed in a 0.1 mol / L FeCl₃ solution (metal element: gallnut gall mass ratio = 1:30), sonicated at 40 kHz for 30 minutes, and centrifuged to obtain the solid. This solid was spread evenly on a 1 mm thick quartz substrate, and a N₂:Ar = 8:2 (v / v) mixed gas was introduced and sealed. Carbonization was then carried out using a CO₂ laser with a power density of 4 kW / cm². 2 The scanning speed was 20 mm / s. After being frozen in liquid nitrogen, the product was circulated five times in a 180 MPa microfluidic homogenizer, dialyzed to remove impurities, and then freeze-dried to obtain a carbon-based material. Its scanning electron microscope image is shown below. Figure 4As shown.

[0114] (2) The dried Sargassum fusiforme raw material was pulverized using a high-speed pulverizer with a 60-mesh sieve, and the sieved powder was collected. The Sargassum fusiforme powder was mixed with 0.1 mol / L NaOH solution at a ratio of 1:10 (g / mL) and stirred at 80°C for 2 hours. After coarse filtration, 10 wt% NaCl solution was added to the filtrate, and the mixture was centrifuged at 12000 rpm for 15 minutes. The supernatant was collected, and 2 volumes of anhydrous ethanol were added dropwise. The precipitate was collected by centrifugation and freeze-dried to obtain brown algae polysaccharide powder.

[0115] (3) The brown algae polysaccharide powder and carbon-based materials were dispersed together in deionized water to prepare a mixed solution containing 3wt% brown algae polysaccharide and 2wt% carbon-based materials. The solution was homogenized at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0116] (4) The precursor was mixed with 1 wt% pregelatinized corn starch solution at a volume ratio of 1:1 and vacuum degassed for 10 minutes. After being injected into a mold, it was immersed in 0.5 mol / L CaCl2 solution for crosslinking for 3 hours, and then transferred to 50℃ deionized water for 24 hours to dissolve the starch, thus obtaining a dual-mode pore hydrogel.

[0117] When the obtained hydrogel is placed on water, the carbon-based material captures sunlight under sunlight and converts the captured sunlight into heat energy using high photothermal conversion efficiency, and evaporates the water in the pores on the surface of the hydrogel.

[0118] Figure 19 The image shown is a scanning electron microscope image of the hydrogel with photothermal conversion capability in Example 8, which clearly shows the interconnected main channels and the nanofiber network on the pore walls.

[0119] Figure 20 The image shows a physical example of the hydrogel with photothermal conversion capability in Example 8. Its homogeneous black appearance indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0120] Performance testing:

[0121] The indoor evaporation experiment used an artificial light source to simulate solar radiation, and the average irradiance of the sample surface was measured to be 1 kW·m using a power meter. -2 In the experiment, the evaporator loaded with hydrogel floated on the water surface, with its upper surface exposed to air. Environmental parameters were controlled at a temperature of 25°C and a relative humidity of 50%. The evaporation rate was determined by measuring water loss every 5 minutes using a balance. The full solar spectrum absorptivity of the material was calculated using its ultraviolet-visible-near-infrared absorption spectrum and standard solar irradiance spectrum. Based on the above experimental data, the photothermal conversion efficiency and energy utilization rate of Examples 1-8 were further obtained, as shown in Table 1.

[0122] Table 1 Test Results of Examples

[0123] Example 1 95.30％ 93.70％ 96.80％ 4.50 Example 2 95.80％ 92.20％ 95.83％ 4.34 Example 3 96.50％ 94.10％ 98.31％ 4.86 Example 4 96.20％ 92.80％ 96.77％ 4.52 Example 5 97.60％ 93.50％ 98.76％ 5.10 Example 6 94.20％ 92.30％ 94.45％ 4.05 Example 7 94.10％ 91.70％ 93.79％ 3.96 Example 8 96.80％ 91.50％ 96.07％ 4.28

[0124] Based on the test data in Table 1, Example 5 achieved 5.10 kg·h using copper salt in combination with the basic formulation. -1 ·m -2 The evaporation rate is significantly improved by copper ions, which simultaneously enhance both absorption rate and energy utilization. Example 3 uses cassava starch to enlarge the pores and improve energy utilization. Examples 6-7 show reduced evaporation rates due to excessively high component concentrations causing pore blockage and decreased energy utilization. Example 8, while increasing laser power to boost absorption, suffers from process defects that reduce conversion efficiency, ultimately limiting the evaporation rate. In conclusion, by using copper salts as the photothermal synergistic component in carbon-based materials and combining them with a dual-mode through-channel structure, the evaporation efficiency of this solar interface evaporator can be significantly improved, reaching a maximum of 5.10 kg·h. -1 ·m -2 This technical solution provides an effective means of developing high-efficiency solar interface evaporators.

[0125] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a solar interface evaporator based on all biomass raw materials, characterized in that, Includes the following steps: (1) Preparation of carbon-based materials derived from gallnut galls: Dried gallnut galls were pulverized, washed and filtered after soaking in dilute acid solution. The resulting filter residue was immersed in a transition metal salt solution, ultrasonically treated, and the solid was separated by centrifugation. This solid was evenly spread on a quartz substrate in a laser reaction chamber, inert gas was introduced and the chamber was sealed, and carbonized by CO2 laser irradiation. The irradiated product was directly transferred to a crushing container, frozen and embrittled, and then circulated in a microfluidic homogenizer. The resulting homogenate was purified to remove impurities and finally dried to obtain carbon-based materials derived from gallnut galls. The transition metal salt was selected from CuSO4·5H2O and FeCl3·6H2O. (2) Obtaining crosslinkable brown algae polysaccharides: Brown algae raw materials are subjected to gradient alkaline extraction to break down the cell wall structure and release polysaccharide components under alkaline conditions. Then, sodium salt solution is added to the system to convert the released polysaccharides into a soluble form. After filtering to remove residue, anhydrous ethanol is added to the solution containing soluble polysaccharides to induce polysaccharide precipitation by controlling the solvent polarity. The precipitate is collected by centrifugation and washed, and finally dried to obtain crosslinkable brown algae polysaccharide powder. (3) Preparation of photothermal composite precursor based on crosslinkable brown algae polysaccharide: crosslinkable brown algae polysaccharide powder is dissolved in deionized water to form a biopolysaccharide solution, and then gall gall-derived carbon-based material is dispersed in the biopolysaccharide solution to prepare a photothermal composite precursor. (4) Preparation of dual-mode pore gel based on crosslinkable brown algae polysaccharide and starch sacrificial template: The photothermal composite precursor obtained in step (3) was mixed with the pregelatinized starch solution at a volume ratio of 1:

1. After vacuum degassing, the mixture was injected into a mold and a divalent cationic crosslinking agent was added to solidify the brown algae network. The gel was immersed in 50°C deionized water to dissolve the starch phase, forming a dual-mode pore structure with template-exfoliated main pores and in-situ self-assembled nanofiber network.

2. The method for preparing a solar interface evaporator based on all biomass raw materials according to claim 1, characterized in that, In step (1), the frequency of the ultrasound is 40 kHz and the duration is 30 minutes.

3. The method for preparing a solar interface evaporator based on all biomass raw materials according to claim 1, characterized in that, In step (1), the power density of the laser is 3.5 kW / cm². 2 The scanning speed is 20 mm / s.

4. The method for preparing a solar interface evaporator based on all biomass raw materials according to claim 1, characterized in that, In step (1), the pressure of the microjet homogenizer is 180 MPa.

5. The method for preparing a solar interface evaporator based on all biomass raw materials according to claim 1, characterized in that, In step (2), the brown algae is selected from either *Sargassum fusiforme* or *Sargassum fusiforme*.

6. The method for preparing a solar interface evaporator based on all biomass raw materials according to claim 1, characterized in that, In step (3), the mass concentration of brown algae polysaccharide in the photothermal composite precursor is 3 wt%, and the mass concentration of carbon-based material is 2 wt%.

7. The method for preparing a solar interface evaporator based on all biomass raw materials according to claim 1, characterized in that, In step (4), the starch is selected from cassava starch and corn starch.

8. The method for preparing a solar interface evaporator based on all biomass raw materials according to claim 1, characterized in that, In step (4), the divalent cationic crosslinking agent is selected from CaCl2 and BaCl2.

9. A solar interface evaporator based on all biomass raw materials, prepared by the preparation method according to any one of claims 1 to 8.

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