Solar interface evaporator based on full-biomass raw materials and preparation method of solar interface evaporator

Abstract

The invention discloses a solar interface evaporator based on full-biomass raw materials and a preparation method of the solar interface evaporator. The method comprises the following steps: firstly, performing dilute acid purification and transition metal loading on gallnut insect galls, performing laser irradiation carbonization to prepare a carbon-based photo-thermal material, and performing alkali extraction and solvent precipitation purification on brown algae to obtain the crosslinkable brown algae polysaccharide. Then, the carbon-based photo-thermal material is dispersed in a fucoidan solution, and a uniform and stable photo-thermal composite precursor is formed through electrostatic adsorption and hydrogen-bond interaction; next, blending the precursor with a pre-gelatinized starch solution, cross-linking and curing an algin network through divalent cations, and soaking in warm water to dissolve out a starch phase, so as to form the hydrogel evaporator with a unique dual-mode through pore channel structure. The obtained biomass-based hydrogel evaporator has a through porous network, the photo-thermal material is stably embedded into the hole wall, and the biomass-based hydrogel evaporator is suitable for the field of solar interface evaporation and has efficient photo-thermal conversion and interface water evaporation capacity.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of soft matter energy materials, and particularly relates to a solar interfacial evaporator based on full biomass raw materials and a preparation method thereof. BACKGROUND

[0002] Solar interfacial evaporation technology has attracted much attention due to its clean solar energy driving, no pollution and no need for complex subsequent treatment. This technology realizes efficient water purification by selectively evaporating liquid at the gas-liquid interface, avoiding the energy waste of traditional bulk heating. The current research focuses on developing high-performance light-to-heat conversion materials (such as polymer aerogels, carbon-based films and composites) to improve evaporation efficiency, and the key technologies focus on two directions: one is to enhance the light-to-heat conversion efficiency by optimizing light absorption and thermal conductivity materials; the other is to build a porous structure to expand the gas-liquid interface contact area, promote the rapid escape of steam and suppress heat dissipation. However, the existing material system still faces problems such as insufficient biocompatibility, unsustainable raw materials or single pore structure. SUMMARY

[0003] The first object of the present application is to provide a preparation method of a solar interfacial evaporator based on full biomass raw materials.

[0004] The second object of the present application is to provide a solar interfacial evaporator based on full biomass raw materials prepared by the above preparation method.

[0005] To achieve the above objects, the technical solutions adopted by the present application are as follows:

[0006] In a first aspect, the present application provides a preparation method of a solar interfacial evaporator based on full biomass raw materials, comprising the following steps:

[0007] (1) Preparation of gall insect gall derived carbon-based material: dry gall insect gall is crushed, soaked and washed with a dilute acid solution and filtered, the obtained filter residue is immersed in a transition metal salt solution, ultrasonically treated, and the solid is separated by centrifugation; the solid is uniformly spread on a quartz substrate in a laser reaction chamber, inert gas is introduced and sealed, and a CO2 laser is used for irradiation carbonization; the product after irradiation is directly transferred to a crushing container, frozen and brittle, and then put into a micro-jet homogenizer for circulation treatment; the obtained homogenate is purified to remove impurities, and finally cold-dried to obtain a gall insect gall derived carbon-based material; the transition metal salt is selected from one of CuSO4·5H2O and FeCl3·6H2O;

[0008] (2) Obtainable cross-linkable alginate polysaccharide: the raw material of brown algae is subjected to gradient alkali extraction treatment, the cell wall structure is destroyed to release polysaccharide components under alkaline conditions, and then a sodium salt solution is added to the system to convert the released polysaccharide into a soluble form; after filtering out the residues, anhydrous ethanol is added to the solution containing the soluble polysaccharide, and the polysaccharide is induced to precipitate by adjusting the polarity of the solvent; the precipitate is collected by centrifugation and washed, and finally the cross-linkable alginate polysaccharide powder is obtained by cold drying;

[0009] (3) Preparation of light-heat composite precursor based on cross-linkable alginate polysaccharide: the cross-linkable alginate polysaccharide powder is dissolved in deionized water to form a biological polysaccharide solution, and then the gall insect gall-derived carbon-based material is dispersed in the biological polysaccharide solution to prepare a light-heat composite precursor;

[0010] (4) Preparation of double-mode channel gel based on cross-linkable alginate polysaccharide and starch: the light-heat composite precursor obtained in step (3) is blended with a pre-gelatinized starch solution at a volume ratio of 1:1, vacuum degassing is performed, and then the mixture is injected into a mold, and a divalent cation cross-linking agent is added to solidify the alginate network; the gel is immersed in 50℃ deionized water to dissolve the starch phase, forming a double-mode pore through channel structure with template stripping main channel and in-situ self-assembled nanofiber network.

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

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

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

[0014] Preferably, in step (2), the brown algae is selected from one of Sargassum muticum and Sargassum fusiforme.

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

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

[0017] Preferably, in step (4), the divalent cation cross-linking agent is selected from one of CaCl2 and BaCl2.

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

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

[0020] 1) The present application provides a new idea of combining brown algae-derived gel with solar clean energy. After transition metal modification and laser carbonization process, the gall insect gall-derived carbon-based material as a light-heat conversion material has a wide solar absorption spectrum and high light-heat conversion efficiency.

[0021] 2) The brown algae-derived hydrogel used in the present application has a dual-mode through-pore structure, good structural stability and high water transport performance. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Flow chart for preparing gall insect gall-derived carbon-based material.

[0023] Figure 2 Flow chart for obtaining cross-linkable brown algae polysaccharide in brown algae.

[0024] Figure 3 Flow chart for preparing dual-mode pore gel.

[0025] Figure 4 Scanning electron microscope image of gall insect gall-derived carbon-based material.

[0026] Figure 5 Scanning electron microscope image of hydrogel with light-heat conversion ability in Example 1.

[0027] Figure 6 Actual image of hydrogel with light-heat conversion ability in Example 1.

[0028] Figure 7 Scanning electron microscope image of hydrogel with light-heat conversion ability in Example 2.

[0029] Figure 8 Actual image of hydrogel with light-heat conversion ability in Example 2.

[0030] Figure 9 Scanning electron microscope image of hydrogel with light-heat conversion ability in Example 3.

[0031] Figure 10 Actual image of hydrogel with light-heat conversion ability in Example 3.

[0032] Figure 11 Scanning electron microscope image of hydrogel with light-heat conversion ability in Example 4.

[0033] Figure 12 Actual image of hydrogel with light-heat conversion ability in Example 4.

[0034] Figure 13 Scanning electron microscope image of hydrogel with light-heat conversion ability in Example 5.

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

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

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

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

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

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

[0041] Figure 20 This is a physical picture of the hydrogel with photothermal conversion capability in Example 8. DETAILED DESCRIPTION

[0042] In order to solve the problem of low performance of photothermal conversion materials in existing solar interface evaporation technology, the embodiment of the present invention proposes a solar interface evaporator based on all-biomass raw materials and a preparation method thereof, which includes the following steps:

[0043] (1) Preparation of gall-derived carbon-based materials: Figure 1 As shown, dried gallnut galls are ground and pulverized, soaked and washed in a dilute acid solution, and filtered. The resulting filter residue is immersed in a transition metal salt solution, subjected to low-frequency ultrasonic treatment, and centrifuged to separate the solid. The solid is evenly spread on a quartz substrate in a laser reaction chamber, an inert gas is introduced, and the chamber is sealed. A high-power laser beam is used to scan and irradiate the solid surface to achieve carbonization. The irradiated product is directly transferred to a crushing container, frozen and embrittled with liquid nitrogen, and then placed in a microfluidizer for circulation treatment. The resulting homogenate is purified and impurities removed, and finally, the gallnut gall-derived carbon-based material is obtained by freeze-drying.

[0044] (2) Obtaining cross-linked brown algae polysaccharides: Figure 2 As shown, the brown algae raw material is subjected to a gradient alkaline extraction treatment, using alkaline conditions to destroy the cell wall structure and release polysaccharide components. Subsequently, a sodium salt solution is added to the system to convert the released polysaccharides into a soluble form. After filtering out the residue, anhydrous ethanol is added to the solution containing soluble polysaccharides, and the polarity of the solvent is controlled to induce the precipitation of polysaccharides. The precipitate is collected by centrifugation and washed, and finally the cross-linked brown algae polysaccharide powder is obtained by freeze-drying.

[0045] (3) Preparation of the photo-thermal composite precursor based on cross-linkable alginate: as shown in Figure 3 , the cross-linkable alginate powder is dissolved in deionized water to form a biopolymer solution, and the gallnut insect gall-derived carbon-based material is dispersed in the biopolymer solution to prepare a photo-thermal composite precursor; in the precursor, the surface of the photo-thermal material is coated with a layer of alginate molecules through electrostatic adsorption and hydrogen bonding, achieving uniform dispersion.

[0046] (4) Preparation of a sacrificial template-induced dual-mode pore gel based on cross-linkable alginate and starch: as shown in Figure 3 , the photo-thermal composite precursor obtained in step (3) is blended with a pre-gelatinized starch solution at a volume ratio of 1:1, vacuum degassed, and then injected into a mold, and a divalent cation cross-linking agent is added to solidify the alginate network; the gel is immersed in 50°C deionized water to dissolve the starch phase, forming a dual-mode pore through-pore structure with a template-stripped main pore and an in-situ self-assembled nanofiber network.

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

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

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

[0050] In some embodiments, in step (2), the brown algae is selected from one of Sargassum muticum and Sargassum fusiforme.

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

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

[0053] In some embodiments, in step (4), the divalent cation cross-linking agent is selected from one of CaCl2 and BaCl2.

[0054] The present application takes a gall insect gall-derived carbon-based material as a light-heat conversion core, and realizes high-efficiency light-heat conversion through transition metal salt modification and high-power laser irradiation process. Meanwhile, a double-mode through-pore structure is constructed by using brown algae polysaccharide and starch: on the one hand, macroscopic main pores are formed by a sacrifice template method to accelerate water transport, and on the other hand, a capillary force and vapor diffusion channel are provided by an in-situ self-assembled nanofiber network. The synergistic effect of the multi-level pores significantly enhances the water transport dynamics and vapor diffusion efficiency, and the all-biomass raw material system ensures the environmental friendliness and sustainability of the material. In addition, the alginate network cross-linked by divalent cations endows the hydrogel with excellent mechanical stability, so that the material has a broad application prospect in the field of high-efficiency solar seawater desalination and wastewater treatment.

[0055] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0056] Embodiment 1

[0057] (1) Crush the dried gall insect gall to pass through a 100-mesh sieve, and immerse it in a 0.5 mol / L H2SO4 solution at a solid-liquid ratio of 1:10 (g / mL) at 25°C for 12 hours. After filtration, the filter residue is immersed in a 0.1 mol / L FeCl3 solution (metal element: gall insect gall mass ratio = 1:30), and ultrasonic treatment is performed at 40 kHz for 30 minutes. The solid is taken by centrifugation. The solid is laid flat on a 1 mm thick quartz substrate, N2:Ar = 8:2 (v / v) mixed gas is introduced and sealed, and carbonization is performed by irradiation with a CO2 laser. The laser power density is 3.5 kW / cm 2 , and the scanning speed is 20 mm / s. The product is frozen with liquid nitrogen, and is treated in a microfluidizer at 180 MPa for 5 cycles. Impurities are removed by dialysis and freeze-drying to obtain a carbon-based material, and the scanning electron microscope image is shown in Figure 4 .

[0058] (2) The dried Sargassum fusiforme raw material is crushed using a high-speed crusher with a 60-mesh screen, and the sieved powder is collected. The Sargassum fusiforme powder is mixed with a 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, 10wt% NaCl solution is added to the filtrate, and centrifuged at 12000 rpm for 15 minutes. The supernatant is collected, 2 volumes of absolute ethanol are added dropwise, and the precipitate is collected by centrifugation. The freeze-dried brown algae polysaccharide powder is obtained.

[0059] (3) The brown algae polysaccharide powder and the carbon-based material are dispersed in deionized water to prepare a mixed solution containing 3wt% brown algae polysaccharide and 2wt% carbon-based material. Homogenization is performed 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 injection into the mold, it was immersed in a 0.5 mol / L CaCl2solution for crosslinking for 3 hours, and then transferred to 50°C deionized water for 24 hours to dissolve the starch, obtaining a double-mode channel hydrogel.

[0061] The obtained hydrogel was placed on the water body, and under sunlight, the carbon-based material could capture sunlight, convert the captured sunlight into heat energy with high photo-thermal conversion efficiency, and evaporate the water in the channels on the surface of the hydrogel.

[0062] Figure 5 The scanning electron microscope image of the hydrogel with photo-thermal conversion ability in Example 1 clearly shows the through main channels and the nanofiber network on the pore wall.

[0063] Figure 6 The actual picture of the hydrogel with photo-thermal conversion ability in Example 1 shows that the homogeneous black appearance indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0064] Example 2

[0065] (1) Crushed dry gallnut insect gall through a 100-mesh sieve, immersed in 0.5 mol / L H2SO4 solution at a solid-liquid ratio of 1:10 (g / mL), and soaked at 25°C for 12 hours. After filtration, the filter residue was immersed in 0.1 mol / L FeCl3 solution (metal element: gallnut insect gall mass ratio = 1:30), and ultrasonicated at 40 kHz for 30 minutes. The solid was obtained by centrifugation. The solid was spread on a 1 mm thick quartz substrate, and a mixture of N2:Ar = 8:2 (v / v) was introduced and sealed. A CO2 laser was used for carbonization, with a laser power density of 3.5 kW / cm 2 , and a scanning speed of 20 mm / s. The product was frozen with liquid nitrogen and treated in a microfluidizer at 180 MPa for 5 cycles. Impurities were removed by dialysis and freeze-dried to obtain a carbon-based material, the scanning electron microscope image of which is shown in Figure 4 .

[0066] (2) The dry iron nail weed material was crushed using a high-speed crusher with a 60-mesh screen, and the sieved powder was collected. The iron nail weed 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 centrifuged at 12000 rpm for 15 minutes. The supernatant was collected and 2 volumes of absolute ethanol were added dropwise. The precipitate was collected by centrifugation and freeze-dried to obtain a fucoidan powder.

[0067] (3) The fucoidan powder and the carbon-based material were dispersed in deionized water to prepare a mixed solution containing 3 wt% fucoidan and 2 wt% carbon-based material. The homogeneous dispersion precursor was obtained by homogenization at 5000 rpm for 1 hour.

[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 injection into the mold, it was immersed in a 0.5 mol / L CaCl2solution for crosslinking for 3 hours, and then transferred to 50°C deionized water for 24 hours to dissolve the starch, obtaining a double-mode channel hydrogel.

[0069] The obtained hydrogel was placed on the water body, and under sunlight, the carbon-based material would capture sunlight, convert the captured sunlight into heat energy with high photo-thermal conversion efficiency, and evaporate the water in the channels on the surface of the hydrogel.

[0070] Figure 7 The scanning electron microscope image of the hydrogel with photo-thermal conversion ability in Example 2 clearly shows the through main channels and the nanofiber network on the pore wall.

[0071] Figure 8 The actual picture of the hydrogel with photo-thermal conversion ability in Example 2 shows that the homogeneous black appearance indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0072] Example 3

[0073] (1) Crush dry gallnut insect gall to 100 mesh, immerse in 0.5 mol / L H2SO4 solution at a solid-liquid ratio of 1:10 (g / mL), and soak at 25°C for 12 hours. After filtration, the filter residue is immersed in a 0.1 mol / L FeCl3 solution (metal element: gallnut insect gall mass ratio = 1:30), and ultrasonic treated at 40 kHz for 30 minutes, and the solid is obtained by centrifugation. The solid is spread on a 1 mm thick quartz substrate, N2:Ar = 8:2 (v / v) mixed gas is introduced and sealed, and carbonization is carried out by irradiation with a CO2 laser, the laser power density is 3.5 kW / cm 2 , the scanning speed is 20 mm / s. The product is frozen by liquid nitrogen, and is treated by a microfluidizer at 180 MPa for 5 cycles, and is dialyzed and freeze-dried to obtain a carbon-based material, and the scanning electron microscope image thereof is shown in Figure 4 .

[0074] (2) The dry Sargassum fusiforme raw material is crushed by a high-speed crusher with a 60-mesh screen, and the sieved powder is collected. The Sargassum fusiforme powder is 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 is added to the filtrate, and centrifuged at 12000 rpm for 15 minutes, and the supernatant is collected, 2 times the volume of absolute ethanol is added dropwise, and the precipitate is collected by centrifugation, and freeze-dried to obtain a fucoidan powder.

[0075] (3) The fucoidan powder and the carbon-based material are dispersed in deionized water to prepare a mixed solution containing 3 wt% fucoidan and 2 wt% carbon-based material, and are 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 injection into the mold, it was immersed in a 0.5 mol / L CaCl2solution for crosslinking for 3 hours, and then transferred to 50°C deionized water for 24 hours to dissolve the starch, obtaining a hydrogel with double-mode channels.

[0077] The obtained hydrogel was placed on the water body, and under sunlight, the carbon-based material would capture sunlight, convert the captured sunlight into heat energy with high photo-thermal conversion efficiency, and evaporate the water in the channels on the surface of the hydrogel.

[0078] Figure 9 The scanning electron microscope image of the hydrogel with photo-thermal conversion ability in Example 3 clearly shows the through main channels and the nanofiber network on the pore wall, and it can be found that the main channels are increased.

[0079] Figure 10 The actual picture of the hydrogel with photo-thermal conversion ability 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) Crushed dry gallnut insect gall powder through a 100-mesh sieve, immersed in a 0.5 mol / L H2SO4solution at a solid-liquid ratio of 1:10 (g / mL) at 25°C for 12 hours. After filtration, the filter residue was immersed in a 0.1 mol / L FeCl3solution (metal element: gallnut insect gall mass ratio = 1:30), and ultrasonicated at 40 kHz for 30 minutes, and the solid was obtained by centrifugation. The solid was spread on a 1 mm thick quartz substrate, and a mixture of N2:Ar = 8:2 (v / v) was introduced and sealed, and carbonized by irradiation with a CO2laser, the laser power density was 3.5 kW / cm 2 , the scanning speed was 20 mm / s. The product was treated by a microfluidizer at 180 MPa for 5 cycles after freezing with liquid nitrogen, and the carbon-based material was obtained by dialysis and freeze-drying, and the scanning electron microscope image thereof is shown in Figure 4 .

[0082] (2) The dry Sargassum fusiforme raw material was crushed using a high-speed crusher with a 60-mesh screen, 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 centrifuged at 12000 rpm for 15 minutes, and the supernatant was collected, 2 times the volume of anhydrous ethanol was added dropwise, and the precipitate was collected by centrifugation, and freeze-dried to obtain a fucoidan powder.

[0083] (3) Disperse the brown algae polysaccharide powder and carbon-based material in deionized water together to prepare a mixed solution containing 3wt% brown algae polysaccharide and 2wt% carbon-based material, and homogenize at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0084] (4) Mix the precursor with 1wt% pregelatinized corn starch solution at a volume ratio of 1:1, and vacuum degas for 10 minutes. After pouring into the mold, immerse it in a 0.5mol / L BaCl2 solution for crosslinking for 3 hours, and then transfer it to a 50℃ deionized water bath for 24 hours to dissolve the starch, obtaining a dual-mode channel hydrogel.

[0085] Place the obtained hydrogel on the water body, and under sunlight, the carbon-based material will capture sunlight, convert the captured sunlight into heat energy with high photo-thermal conversion efficiency, and evaporate the water in the channels on the surface of the hydrogel.

[0086] Figure 11 The scanning electron microscope image of the hydrogel with photo-thermal conversion ability in Example 4 clearly shows the through main channels and the nanofiber network on the pore wall.

[0087] Figure 12 The actual picture of the hydrogel with photo-thermal conversion ability in Example 4 shows that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0088] Example 5

[0089] (1) Crush dry gall insect gall to pass through a 100-mesh sieve, and immerse it in a 0.5mol / L H2SO4 solution at a solid-liquid ratio of 1:10 (g / mL) at 25℃ for 12 hours. After filtration, immerse the residue in a 0.1mol / L CuSO4 solution (metal element: gall insect gall mass ratio = 1:30), and treat it with ultrasonic waves at 40kHz for 30 minutes, and then centrifuge to obtain the solid. Spread the solid on a 1mm-thick quartz substrate, introduce N2:Ar = 8:2 (v / v) mixed gas and seal, and irradiate it with a CO2 laser to carbonize, with a laser power density of 3.5kW / cm 2 , and a scanning speed of 20mm / s. After freezing the product in liquid nitrogen, treat it with a microfluidizer at 180MPa for 5 cycles, dialysis and freeze-drying to obtain a carbon-based material, and its scanning electron microscope image is shown in Figure 4 .

[0090] (2) Use a high-speed pulverizer with a 60-mesh screen to crush dry Sargassum fusiforme raw material, and collect the sieved powder. Mix the Sargassum fusiforme powder with a 0.1mol / L NaOH solution at a ratio of 1:10 (g / mL), and stir at 80℃ for 2 hours. After coarse filtration, add a 10wt% NaCl solution to the filtrate, centrifuge at 12000 rpm for 15 minutes, and then add 2 volumes of absolute ethanol to the supernatant, and centrifuge to collect the precipitate, and freeze-dry to obtain brown algae polysaccharide powder.

[0091] (3) Disperse the brown algae polysaccharide powder and the carbon-based material in deionized water together to prepare a mixed solution containing 3 wt% brown algae polysaccharide and 2 wt% carbon-based material, and homogenize at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0092] (4) Mix the precursor with 1 wt% pregelatinized corn starch solution at a volume ratio of 1:1, and vacuum degas for 10 minutes. After pouring into a mold, immerse in a 0.5 mol / L CaCl2solution for crosslinking for 3 hours, and then transfer to 50°C deionized water for 24 hours to dissolve the starch, thereby obtaining a dual-mode channel hydrogel.

[0093] Place the obtained hydrogel on the water body, and under sunlight, the carbon-based material will capture sunlight, convert the captured sunlight into heat energy by high photo-thermal conversion efficiency, and evaporate the water in the channels on the surface of the hydrogel.

[0094] Figure 13 The scanning electron microscope image of the hydrogel with photo-thermal conversion capability in Example 5 clearly shows the through main channels and the nanofiber network on the pore wall.

[0095] Figure 14 The actual picture of the hydrogel with photo-thermal conversion capability in Example 5 shows that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0096] Example 6

[0097] (1) Crush dry gall insect gall to pass through a 100-mesh sieve, and immerse in a 0.5 mol / L H2SO4solution at a solid-liquid ratio of 1:10 (g / mL) at 25°C for 12 hours. After filtration, immerse the filter residue in a 0.1 mol / L FeCl3solution (metal element: gall insect gall mass ratio = 1:30), and perform ultrasonic treatment at 40 kHz for 30 minutes, and then centrifuge to obtain the solid. Spread the solid on a 1-mm-thick quartz substrate, introduce N2:Ar = 8:2 (v / v) mixed gas, and seal, and then irradiate with a CO2laser to carbonize, with a laser power density of 3.5 kW / cm 2 , and a scanning speed of 20 mm / s. After freezing the product in liquid nitrogen, perform circulation treatment in a 180 MPa microfluidizer for 5 times, dialysis to remove impurities, and freeze-drying to obtain a carbon-based material, and the scanning electron microscope image thereof is shown in Figure 4 .

[0098] (2) Use a high-speed pulverizer with a 60-mesh screen to crush dry Sargassum fusiforme raw material, and collect the sieved powder. Mix the Sargassum fusiforme powder with a 0.1 mol / L NaOH solution at a ratio of 1:10 (g / mL), and stir at 80°C for 2 hours. After coarse filtration, add a 10 wt% NaCl solution to the filtrate, centrifuge at 12000 rpm for 15 minutes, and then add 2 volumes of absolute ethanol to the supernatant, and centrifuge to collect the precipitate, and freeze-dry to obtain brown algae polysaccharide powder.

[0099] (3) Disperse the brown algae polysaccharide powder and the carbon-based material in deionized water together to prepare a mixed solution containing 3 wt% brown algae polysaccharide and 2 wt% carbon-based material, homogenize at 5000 rpm for 1 hour to form a uniformly dispersed precursor.

[0100] (4) Mix the precursor with a 6 wt% pregelatinized corn starch solution at a volume ratio of 1:1, and vacuum degas for 10 minutes. After pouring into a mold, immerse it in a 0.5 mol / L CaCl2 solution for crosslinking for 3 hours, and then transfer it to 50°C deionized water for 24 hours to dissolve the starch, obtaining a dual-mode channel hydrogel.

[0101] Place the obtained hydrogel on the water body, and under sunlight, the carbon-based material will capture sunlight, convert the captured sunlight into heat energy with high photo-thermal conversion efficiency, and evaporate the water in the channels on the surface of the hydrogel.

[0102] Figure 15 The scanning electron microscope image of the hydrogel with photo-thermal conversion ability in Example 6 clearly shows the through main channels and the nanofiber network on the pore wall.

[0103] Figure 16 The actual picture of the hydrogel with photo-thermal conversion ability in Example 6 shows that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0104] Example 7

[0105] (1) Crush dry gall insect gall to pass through a 100-mesh sieve, and immerse it in a 0.5 mol / L H2SO4 solution at a solid-liquid ratio of 1:10 (g / mL) at 25°C for 12 hours. After filtration, immerse the filter residue in a 0.1 mol / L FeCl3 solution (metal element: gall insect gall mass ratio = 1:30), and treat it with ultrasonic waves at 40 kHz for 30 minutes, and then centrifuge to obtain the solid. Spread the solid on a 1-mm-thick quartz substrate, introduce N2:Ar = 8:2 (v / v) mixed gas and seal, carbonize by irradiation with a CO2 laser, and the laser power density is 3.5 kW / cm 2 , and the scanning speed is 20 mm / s. After freezing the product in liquid nitrogen, treat it in a microfluidizer at 180 MPa for 5 cycles, dialyze and freeze-dry to obtain the carbon-based material, and its scanning electron microscope image is shown in Figure 4 .

[0106] (2) The dried Sargassum yezoense raw material was pulverized using a high-speed pulverizer with a 60-mesh screen, and the sieved powder was collected. The Sargassum yezoense 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, the filtrate was added with 10 wt% NaCl solution, and centrifuged at 12000 rpm for 15 minutes. The supernatant was added dropwise with 2 times the volume of anhydrous ethanol, and the precipitate was collected by centrifugation. The brown algal polysaccharide powder was obtained by freeze-drying.

[0107] (3) The brown algal polysaccharide powder and the carbon-based material were dispersed in deionized water to prepare a mixed solution containing 4 wt% brown algal polysaccharide and 2 wt% carbon-based material. 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% pre-gelatinized corn starch solution at a volume ratio of 1:1, and vacuum degassed for 10 minutes. After being injected into the mold, it was immersed in 0.5 mol / L CaCl2 solution for crosslinking for 3 hours, and then transferred to 50°C deionized water for 24 hours to dissolve the starch, obtaining a dual-mode channel hydrogel.

[0109] The obtained hydrogel was placed on the water body, and under sunlight, the carbon-based material would capture sunlight, convert the captured sunlight into heat energy with high light-heat conversion efficiency, and evaporate the water in the channels on the surface of the hydrogel.

[0110] Figure 17 The scanning electron microscope image of the hydrogel with light-heat conversion ability in Example 7 clearly shows the through main channels and the nanofiber network on the pore wall, and compared with other examples, the number of main channels is reduced.

[0111] Figure 18 The actual picture of the hydrogel with light-heat conversion ability in Example 7 shows that the uniform black appearance of the hydrogel indicates that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0112] Example 8

[0113] (1) The dried gall insect gall was crushed to pass through a 100-mesh sieve, and then immersed in 0.5 mol / L H2SO4 solution at a solid-liquid ratio of 1:10 (g / mL) at 25°C for 12 hours. After filtration, the residue was immersed in 0.1 mol / L FeCl3 solution (metal element: gall insect gall mass ratio = 1:30), and ultrasonicated at 40 kHz for 30 minutes. The solid was collected by centrifugation. The solid was spread on a 1 mm thick quartz substrate, and a mixture of N2:Ar = 8:2 (v / v) was introduced and sealed. A CO2 laser was used for carbonization. The laser power density was 4 kW / cm 2 , and the scanning speed was 20 mm / s. The product was treated by liquid nitrogen freezing and 180 MPa microfluidizer for 5 cycles. The impurities were removed by dialysis and freeze-dried to obtain a carbon-based material. The scanning electron microscope image of the carbon-based material is as follows: Figure 4as shown.

[0114] (2) The dry Sargassum yezoense raw material was pulverized using a high-speed pulverizer with a 60-mesh screen, and the sieved powder was collected. The Sargassum yezoense 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 centrifuged at 12000 rpm for 15 minutes. The supernatant was collected, 2 times the volume of anhydrous ethanol was added dropwise, and the precipitate was collected by centrifugation and freeze-dried to obtain a brown algal polysaccharide powder.

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

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

[0117] The obtained hydrogel was placed on the water surface, and under sunlight, the carbon-based material would capture sunlight, convert the captured sunlight into heat energy with high photo-thermal conversion efficiency, and evaporate the water in the channels on the surface of the hydrogel.

[0118] Figure 19 The scanning electron microscope image of the hydrogel with photo-thermal conversion ability in Example 8 clearly shows the through main channels and the nanofiber network on the pore wall.

[0119] Figure 20 The actual picture of the hydrogel with photo-thermal conversion ability in Example 8 shows that the carbon-based material has been uniformly dispersed in the hydrogel matrix.

[0120] Performance test:

[0121] The indoor evaporation experiment used artificial light sources to simulate solar radiation, and the average irradiance on the surface of the sample was measured to be 1 kW·m -2 During the experiment, the water evaporation device loaded with the hydrogel floated on the water surface, and its upper surface was exposed to the air. The environmental parameters were controlled at a temperature of 25°C and a relative humidity of 50%. The water loss was measured every 5 minutes by a balance to determine the evaporation rate. The total solar spectrum absorption rate of the material was calculated based on its ultraviolet-visible-near infrared absorption spectrum and the standard solar radiation spectrum. Based on the above experimental data, the photo-thermal conversion rate 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 Solar light absorption rate Photo-thermal conversion rate Energy utilization rate Evaporation rate (kg·h -1 ·m -2 )]]> 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] According to the test data in Table 1, the evaporation rate of Example 5 is 5.10 kg·h -1 ·m -2 , which is an advantage of the copper ions that synchronously improve the absorption rate and energy utilization. Example 3 uses cassava starch to expand the pore channel and improve the energy utilization. Examples 6-7 have high component concentration, which leads to pore channel blockage and energy utilization reduction, and the evaporation rate is reduced. Example 8 increases the laser power to increase the absorption rate, but the conversion rate is reduced due to process defects, and the final evaporation rate is limited. In summary, by using copper salt as the light-heat synergistic component of carbon-based materials and cooperating with the double-mode through-pore channel structure, the evaporation efficiency of the solar interface evaporator can be significantly improved, and the highest evaporation rate is 5.10 kg·h -1 ·m -2 . The technical scheme provides an effective implementation means for the development of a high-efficiency solar interface evaporator.

[0125] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any modification, equivalent replacement and improvement within the technical range disclosed in the present application, which is within the spirit and principles of the present application, should be covered within the protection scope of the present application.

Claims

1. A method for preparing a solar interface evaporator based on all-biomass raw materials, characterized in that: The following steps are involved: (1) Preparation of gall-derived carbon-based materials: dried gall-derived galls are crushed, washed with a dilute acid solution, and filtered. The resulting filter residue is immersed in a transition metal salt solution, ultrasonically treated, and centrifuged to separate the solid. The solid is evenly spread on a quartz substrate in a laser reaction chamber, introduced with an inert gas and sealed, and carbonized by irradiation with a CO2 laser. The irradiated product is directly transferred to a crushing container, frozen and embrittled, and then placed in a microfluidizer for circulation treatment. The resulting homogenate is purified and impurities removed, and finally freeze-dried to obtain the gall-derived carbon-based material. The transition metal salt is selected from one of CuSO4·5H2O and FeCl3·6H2O. (2) Obtaining cross-linked brown algae polysaccharide: The brown algae raw material is subjected to gradient alkaline extraction treatment, and the cell wall structure is destroyed under alkaline conditions to release the polysaccharide components. Subsequently, a sodium salt solution is added to the system to convert the released polysaccharide into a soluble form; after filtering out the residue, anhydrous ethanol is added to the solution containing the soluble polysaccharide, and the polarity of the solvent is controlled to induce the precipitation of the polysaccharide; the precipitate is collected by centrifugation and washed, and finally freeze-dried to obtain the cross-linked brown algae polysaccharide powder; (3) Preparation of a photothermal composite precursor based on cross-linkable fucoidan: dissolving the cross-linkable fucoidan powder in deionized water to form a biopolysaccharide solution, and then dispersing the gall-derived carbon-based material in the biopolysaccharide solution to prepare a photothermal composite precursor; (4) Preparation of a sacrificial template-induced dual-mode pore gel based on cross-linkable brown algae polysaccharide and starch: The photothermal composite precursor obtained in step (3) was mixed with the pregelatinized starch solution in a volume ratio of 1:1, injected into a mold after vacuum degassing, and a divalent cationic crosslinker was added to solidify the alginate network; the gel was immersed in 50°C deionized water to dissolve the starch phase, forming a dual-mode pore structure with a template-stripped main pore and an 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 time 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 laser power density is 3.5kW / cm 2 , scanning speed 20mm / 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 microfluidizer 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 one of the group consisting of kelp and fusiformes.

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 fucoidan in the photothermal composite precursor is 3 wt %, and the mass concentration of the 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 one of tapioca 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 one of 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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