Preparation method and application of modified carbon-based photothermal conversion material

Abstract

The invention discloses a preparation method and application of a modified carbon-based photothermal conversion material, and belongs to the technical field of photothermal conversion materials. Waste biomass is used as a carbon source to prepare the carbon ink, waste resource reutilization is achieved, through staged temperature control carbonization and activation treatment, the pore structure and surface activity of biomass carbon powder are effectively improved, the interface bonding force and wetting permeability between carbon particles and dust-free paper are remarkably enhanced, modification is more uniform and firmer, and the service life of the dust-free paper is prolonged. The modified carbon-based photo-thermal conversion material has the advantages that the modified carbon-based photo-thermal conversion material is modified, so that the mechanical stability and durability of the material are improved, excellent loading and distribution with dust-free paper can be achieved, the photo-thermal conversion material with more excellent comprehensive performance can be obtained, and in addition, the modified carbon-based photo-thermal conversion material can further improve the high absorptivity (gt; 90%), the material has excellent light capturing ability, the surface of the material can be rapidly heated under illumination, a high steady-state temperature can be maintained under one sunlight intensity, and the photothermal conversion efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of photothermal conversion materials technology, and more specifically, to a method for preparing a modified carbon-based photothermal conversion material and its application. Background Technology

[0002] Freshwater is an essential material basis for human survival, but it accounts for only about 2.7% of the world's total water resources, with readily available freshwater for human use being particularly scarce. Although China ranks among the world's top countries in terms of total freshwater resources, its per capita availability is only one-quarter of the world average, highlighting the increasingly prominent contradiction between water supply and demand. Meanwhile, seawater accounts for 97.3% of the Earth's total water resources, making seawater desalination a crucial way to alleviate freshwater shortages.

[0003] Solar energy, as a clean, renewable, and widely distributed energy source, has shown great potential in the field of seawater desalination. Solar interfacial evaporation technology, by placing photothermal materials at the water-air interface, achieves localized absorption and conversion of solar energy, thereby efficiently increasing the evaporation rate, and has become a research hotspot in recent years. The core of this technology lies in developing efficient, low-cost, and easily prepared photothermal conversion materials.

[0004] Currently, photothermal materials are mainly classified into four categories: metal nanomaterials, semiconductor materials, organic polymer materials, and carbon-based materials. Among them, carbon-based materials are considered one of the most promising photothermal materials due to their wide availability, low cost, good chemical stability, and excellent light absorption performance. Existing research has reported the application of various carbon-based materials such as carbon fibers, carbon nanotubes, graphene, carbon black, and biomass carbon in photothermal evaporation, but problems remain, including complex preparation processes, high costs, difficulties in large-scale production, and limited light absorption bandwidth. In particular, traditional carbon black particulate-based materials still have significant room for improvement in evaporation rate and photothermal conversion efficiency.

[0005] In existing technologies, researchers have explored various carbon-based photothermal materials. For example, Dongdong Tong et al. used carbon fiber fabric as the photothermal conversion material, designed a multi-layer carbon fiber fabric structure, and promoted heat transfer between layers and surface heat conversion by means of copper coating on the middle layer fabric and etching the surface layer fabric, which greatly improved the evaporation rate. Under one solar intensity, the evaporation rate of seawater reached 3.39 kg / (m²). 2 Li Meng et al. prepared CNT / PVA-SA three-dimensional aerogel photothermal conversion materials with different sizes of vertical pores by combining carbon nanotubes (CNTs) with polyvinyl alcohol (PVA) and sodium alginate (SA) through directional freezing. The evaporation rate reached 2.7 kg / (m²). 2(h). Although the evaporation rate is relatively high, the preparation process is complex and not suitable for large-scale production. Furthermore, biomass carbon and nano-carbon black-based photothermal materials also suffer from relatively low evaporation rates. Overall, carbon-based photothermal conversion materials still face challenges and limitations in raw material development, preparation processes, and material structure and properties. Further research and optimization of the structure and properties of carbon-based photothermal conversion materials are needed to improve their solar energy absorption and conversion efficiency. Additionally, it is necessary to explore more abundant carbon materials, research new preparation methods and technologies, reduce preparation costs, and improve the preparation efficiency and quality of carbon materials.

[0006] Therefore, developing a carbon-based photothermal conversion material with widely available raw materials, simple preparation process, low cost, excellent light absorption performance, and high evaporation efficiency is of great significance for promoting the practical application of solar interfacial evaporation technology. Summary of the Invention

[0007] In view of this, and in order to solve one of the above-mentioned technical problems, the present invention provides a method for preparing modified carbon-based photothermal conversion materials and their applications, the specific technical solution of which is as follows: A method for preparing a modified carbon-based photothermal conversion material, the method comprising the following steps: S1. The crushed biomass raw material is subjected to carbonization and grinding to obtain biomass carbon powder; S2. According to the composition ratio of carbon ink, the carbon ink is prepared by ball milling. S3. Mix the carbon ink prepared in step S2 with deionized water and disperse it evenly to obtain an ink dispersion; S4. Immerse the dust-free paper in the ink dispersion until it is completely submerged, and perform ultrasonic-assisted modification treatment to obtain ink-modified dust-free paper. S5. The ink-modified dust-free paper is taken out and dried to obtain the modified carbon-based photothermal conversion material.

[0008] In one embodiment, the biomass raw material is at least one of crop straw, rice husk, wood, bamboo, fruit shell, and algae.

[0009] In one embodiment, the carbonization process involves heating to 350°C at a rate of 1°C / min to 3°C / min under an inert gas atmosphere and holding at that temperature for 30 min to 60 min; then heating to 650°C to 800°C at a rate of 8°C / min to 10°C / min and holding at that temperature for 1 h to 3 h.

[0010] In one embodiment, the grinding process involves adding the ball to a planetary ball mill at a ball-to-material ratio of (10~15):1 and grinding at a speed of 300r / min~600r / min for 1h~2h.

[0011] In one embodiment, the carbon ink comprises the following raw materials in parts by weight: 9 to 15 parts of biomass toner, 1 to 2 parts of carboxymethyl hydroxypropyl xanthan gum, 0.5 to 3 parts of dispersant, 0.1 to 0.5 parts of coupling agent, 1 to 3 parts of humectant, 0.1 to 0.5 parts of stabilizer, and 0.1 to 3 parts of surfactant.

[0012] In one embodiment, in step S2, the ball milling conditions are: processing at a rotation speed of 100 r / min to 500 r / min for 1 h to 2 h.

[0013] In one embodiment, in step S3, the volume ratio of carbon ink to deionized water is (1~5):(10~50).

[0014] In one embodiment, in step S4, the power of the ultrasonic-assisted modification treatment is 100W~500W, and the time is 10min~60min.

[0015] In one embodiment, in step S5, the drying temperature is 60°C to 100°C and the time is 1 hour to 4 hours.

[0016] In addition, the present invention also provides an application of the modified carbon-based photothermal conversion material, wherein the modified carbon-based photothermal conversion material prepared by the preparation method is used in a solar interface evaporation system, which is applicable to the fields of seawater desalination, wastewater evaporation and concentration or photothermal steam power generation.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses waste biomass as a carbon source to prepare carbon ink, realizing the reuse of waste resources. The material source is wide and conforms to the concept of green recycling. Through staged temperature-controlled carbonization and activation treatment, the pore structure and surface activity of biomass carbon powder are effectively improved, laying a structural foundation for its efficient photothermal conversion. After optimized compounding, the carbon ink has excellent overall dispersibility and stability, significantly enhancing the interfacial bonding force and wetting penetration between carbon particles and cleanroom paper fibers, making the modification more uniform and firm, thereby improving the mechanical stability and durability of the material. It can achieve excellent loading and distribution with cleanroom paper, which is conducive to obtaining photothermal conversion materials with better comprehensive performance.

[0018] 2. The modified carbon-based photothermal conversion material of the present invention can further improve the high absorption rate (>90%) of full-spectrum sunlight in the range of 250~2500nm, has excellent light-harvesting ability, and the material surface can achieve rapid heating under illumination and maintain a high steady-state temperature under 1 solar intensity, resulting in high photothermal conversion efficiency.

[0019] In solar interface evaporation applications, evaporation rates for pure water, simulated seawater, and high-concentration brine are expected to remain at high levels, with evaporation efficiency anticipated to exceed 92%. Self-made biomass carbon ink may offer better resistance to salt precipitation and improved long-term operational stability. Attached Figure Description

[0020] The invention can be understood from the following description taken in conjunction with the accompanying drawings in one embodiment. The components in the drawings are not necessarily drawn to scale, but rather the emphasis is on illustrating the principles of the embodiments. In different views, the same reference numerals designate corresponding parts.

[0021] Figure 1 Infrared spectra of cleanroom paper, carbon ink-modified cleanroom paper, and carbon ink; Figure 2 This is a schematic diagram showing the solar spectrum reflectance of the modified carbon-based photothermal conversion materials and dust-free paper prepared in Examples 1-3 of the present invention. Figure 3 This is a schematic diagram showing the surface temperature change curves of the modified carbon-based photothermal conversion materials and the dust-free paper prepared in Examples 1-3 of this invention. Figure 4 A schematic diagram simulating the rate of seawater evaporation; Figure 5 This is a schematic diagram of the simulated seawater evaporation rate of the modified carbon-based photothermal conversion materials prepared in Examples 1-3 of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail below with reference to one embodiment. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of the invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] A method for preparing a modified carbon-based photothermal conversion material according to an embodiment of the present invention includes the following steps: S1. The crushed biomass raw material is subjected to carbonization and grinding to obtain biomass carbon powder; S2. According to the composition ratio of carbon ink, the carbon ink is prepared by ball milling. S3. Mix the carbon ink prepared in step S2 with deionized water and disperse it evenly to obtain an ink dispersion; S4. Immerse the dust-free paper in the ink dispersion until it is completely submerged, and perform ultrasonic-assisted modification treatment to obtain ink-modified dust-free paper. S5. The ink-modified dust-free paper is taken out and dried to obtain the modified carbon-based photothermal conversion material.

[0025] In one embodiment, the biomass raw material is at least one of crop straw, rice husk, wood, bamboo, fruit shell, and algae.

[0026] In one embodiment, the carbonization process involves heating to 350°C at a rate of 1°C / min to 3°C / min under an inert gas atmosphere and holding at that temperature for 30 min to 60 min; then heating to 650°C to 800°C at a rate of 8°C / min to 10°C / min and holding at that temperature for 1 h to 3 h.

[0027] In one embodiment, the inert gas is nitrogen and / or argon.

[0028] In one embodiment, the grinding process involves adding the ball to a planetary ball mill at a ball-to-material ratio of (10~15):1 and grinding at a speed of 300r / min~600r / min for 1h~2h.

[0029] In one embodiment, the carbon ink comprises the following raw materials in parts by weight: 9-15 parts biomass carbon powder, 1-2 parts carboxymethyl hydroxypropyl xanthan gum, 0.5-3 parts dispersant, 0.1-0.5 parts coupling agent, 1-3 parts humectant, 0.1-0.5 parts stabilizer, 0.1-3 parts surfactant, and 40-50 parts water. This invention optimizes the composition and ratio of the carbon ink, resulting in a carbon ink with excellent dispersion and suspension properties, superior stability, and better interfacial bonding with cleanroom paper, exhibiting excellent wetting and penetration.

[0030] In one embodiment, the dispersant is at least one of polyvinylpyrrolidone, polyethylene glycol, polypropylene glycol, sodium carboxymethyl cellulose, sodium dodecylbenzene sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, hexadecyltrimethylammonium bromide, dodecyl dimethyl benzyl ammonium chloride, and polyoxyethylene fatty alcohol ether.

[0031] In one embodiment, the coupling agent is at least one of γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, and γ-mercaptopropyltrimethoxysilane.

[0032] In one embodiment, the humectant is at least one selected from 1,4-butanediol, dipropylene glycol, ethanol, isobutanol, and ethylene glycol.

[0033] In one embodiment, the stabilizer is at least one of coconut oil diethanolamide, hydrogenated castor oil, and ethylene glycol monobutyl ether.

[0034] In one embodiment, the surfactant is at least one of sodium dodecyl sulfonate, lauryl sulfate, sodium alkyl sulfonate, alkylphenol polyoxyethylene ether, alkyl alcohol polyoxyethylene ether, ethylene glycol polyoxyethylene alkyl ester, and nonylphenol.

[0035] In one embodiment, in step S2, the ball milling conditions are: processing at a rotation speed of 100 r / min to 500 r / min for 1 h to 2 h.

[0036] In one embodiment, the carbon ink has a particle size D50 ≤ 0.5 μm.

[0037] In one embodiment, in step S3, the volume ratio of carbon ink to deionized water is (1~5):(10~50).

[0038] In one embodiment, in step S4, the power of the ultrasonic-assisted modification treatment is 100W~500W, and the time is 10min~60min.

[0039] In one embodiment, in step S4, the thickness of the dust-free paper is 0.2mm to 0.5mm, the porosity is greater than 80%, and the average pore size is 10μm to 40μm.

[0040] In one embodiment, in step S5, the drying temperature is 60°C to 100°C and the time is 1 hour to 4 hours.

[0041] In addition, the present invention also provides an application of the modified carbon-based photothermal conversion material, wherein the modified carbon-based photothermal conversion material prepared by the preparation method is used in a solar interface evaporation system, which is applicable to the fields of seawater desalination, wastewater evaporation and concentration or photothermal steam power generation.

[0042] This invention uses cleanroom paper as the matrix and carbon ink as the carbon source. It leverages the advantages of cleanroom paper's loose structure, good strength, and excellent water transport properties, combined with the high light absorption and photothermal conversion efficiency of carbon particles in the ink, to prepare a novel carbon-based photothermal conversion material for solar interfacial evaporation by modifying the cleanroom paper with ink. Compared to the preparation of other carbon-based photothermal conversion materials such as carbon fibers, carbon nanotubes, graphene, and biomass carbon, this method is simpler, uses widely available, stable, and easily stored raw materials, and has lower production costs. The material prepared by this invention exhibits excellent photothermal conversion performance, achieving an absorption rate of over 90% for the full spectrum of sunlight in the 250–2500 nm range. Under irradiation with 1 solar intensity, the material surface temperature rises to 75.6℃ in 1 minute and 80.5℃ in 3 minutes. Simultaneously, under irradiation with 1 solar intensity, using the designed evaporator, the evaporation rates of pure water, simulated seawater (3.5 wt% sodium chloride solution), and 10 wt% sodium chloride solution reached 2.2471 kg·m³, respectively. -2 ·h -1 2.2262 kg·m -2 ·h -1 and 2.1964 kg·m -2 ·h -1 Compared with existing technologies, the present invention has a more efficient evaporation rate, and the evaporation efficiency reaches more than 92.3%.

[0043] The implementation schemes of the present invention will now be described in detail with reference to specific embodiments.

[0044] Example 1: A method for preparing a modified carbon-based photothermal conversion material includes the following steps: S1. The fruit shells were crushed and used as biomass raw material. Under a nitrogen atmosphere, the temperature was increased to 350℃ at a heating rate of 3℃ / min and held for 35min. Then, the temperature was increased to 800℃ at a heating rate of 10℃ / min and held for 2h. The material was then added to a planetary ball mill at a ball-to-material ratio of 10:1 and ball-milled at a speed of 300r / min for 1h to obtain biomass carbon powder. S2. According to the weight ratio, 12 parts of biomass carbon powder and 0.5 parts of γ-mercaptopropyltriethoxysilane were mixed and treated for 15 min. Then, 2 parts of carboxymethyl hydroxypropyl xanthan gum, 1 part of polyvinylpyrrolidone, 2 parts of dipropylene glycol, 0.3 parts of coconut oil diethanolamide, 1 part of sodium dodecyl sulfonate and 50 parts of water were added. The mixture was ball-milled at 300 r / min for 2 h to prepare carbon ink. S3. Mix the carbon ink prepared in step S2 with deionized water (the volume ratio of carbon ink to deionized water is 3:50) and disperse evenly to obtain an ink dispersion. S4. Immerse a 0.3 mm thick, 85% porosity, and 20 μm average pore size clean paper into the ink dispersion to completely submerge it, and perform ultrasonic-assisted modification treatment at 100 W power for 30 min to obtain ink-modified clean paper. S5. Take out the ink-modified dust-free paper and dry it at 85°C for 1 hour to obtain the modified carbon-based photothermal conversion material.

[0045] Example 2: A method for preparing a modified carbon-based photothermal conversion material includes the following steps: S1. The fruit shells were crushed and used as biomass raw material. Under a nitrogen atmosphere, the temperature was increased to 350℃ at a heating rate of 3℃ / min and held for 35min. Then, the temperature was increased to 800℃ at a heating rate of 10℃ / min and held for 2h. The material was then added to a planetary ball mill at a ball-to-material ratio of 10:1 and ball-milled at a speed of 300r / min for 1h to obtain biomass carbon powder. S2. According to the weight ratio, 13 parts of biomass carbon powder and 0.4 parts of γ-mercaptopropyltriethoxysilane were mixed and treated for 20 min. Then, 2 parts of carboxymethyl hydroxypropyl xanthan gum, 1 part of polyvinylpyrrolidone, 3 parts of dipropylene glycol, 0.3 parts of coconut oil diethanolamide, 1 part of sodium dodecyl sulfonate and 50 parts of water were added. The mixture was ball-milled at 300 r / min for 2 h to prepare carbon ink. S3. Mix the carbon ink prepared in step S2 with deionized water (the volume ratio of carbon ink to deionized water is 3:50) and disperse evenly to obtain an ink dispersion. S4. Immerse a 0.3 mm thick, 85% porosity, and 20 μm average pore size clean paper into the ink dispersion to completely submerge it, and perform ultrasonic-assisted modification treatment at 100 W power for 30 min to obtain ink-modified clean paper. S5. Take out the ink-modified dust-free paper and dry it at 85°C for 1 hour to obtain the modified carbon-based photothermal conversion material.

[0046] Example 3: A method for preparing a modified carbon-based photothermal conversion material includes the following steps: S1. The fruit shells were crushed and used as biomass raw materials. Under a nitrogen atmosphere, the temperature was increased to 350℃ at a heating rate of 3℃ / min and held for 30min. Then, the temperature was increased to 800℃ at a heating rate of 10℃ / min and held for 2h. The raw materials were then added to a planetary ball mill at a ball-to-material ratio of 10:1 and ball-milled at a speed of 300r / min for 1h to obtain biomass carbon powder. S2. According to the weight ratio, 13 parts of biomass carbon powder and 0.3 parts of γ-mercaptopropyltriethoxysilane were mixed and treated for 20 min. Then, 2 parts of carboxymethyl hydroxypropyl xanthan gum, 1 part of polyvinylpyrrolidone, 2 parts of dipropylene glycol, 0.4 parts of coconut oil diethanolamide, 1 part of sodium dodecyl sulfonate and 50 parts of water were added. The mixture was ball-milled at 300 r / min for 2 h to prepare carbon ink. S3. Mix the carbon ink prepared in step S2 with deionized water (the volume ratio of carbon ink to deionized water is 3:50) and disperse evenly to obtain an ink dispersion. S4. Immerse a 0.3 mm thick, 85% porosity, and 20 μm average pore size clean paper into the ink dispersion to completely submerge it, and perform ultrasonic-assisted modification treatment at 100 W power for 30 min to obtain ink-modified clean paper. S5. Take out the ink-modified dust-free paper and dry it at 85°C for 1 hour to obtain the modified carbon-based photothermal conversion material.

[0047] Comparative Example 1: The difference between Comparative Example 1 and Example 3 is that the cleanroom paper in Comparative Example 1 was not modified; it was simply a cleanroom paper with a thickness of 0.3 mm, a porosity of 85%, and an average pore size of 20 μm.

[0048] In addition, combined Figures 1-5 Analyzing this invention, Figure 1 Infrared spectra of cleanroom paper, carbon ink-modified cleanroom paper, and carbon ink; Figure 2 This is a schematic diagram showing the solar spectrum reflectance of the modified carbon-based photothermal conversion materials and dust-free paper prepared in Examples 1-3 of the present invention. Figure 3 This is a schematic diagram showing the surface temperature change curves of the modified carbon-based photothermal conversion materials and the dust-free paper prepared in Examples 1-3 of this invention. Figure 4 A schematic diagram simulating the rate of seawater evaporation; Figure 5This diagram illustrates the simulated seawater evaporation rate of the modified carbon-based photothermal conversion materials prepared in Examples 1-3 of this invention. Analysis of the diagrams shows that this invention uses cleanroom paper as the matrix and carbon ink as the carbon source. It leverages the advantages of the loose structure and good strength of the cleanroom paper, as well as its excellent water transport properties, and the high light absorption and photothermal conversion efficiency of the carbon particles in the ink. By modifying the cleanroom paper with ink, a carbon-based photothermal conversion material for solar interface evaporation is prepared. Overall, it exhibits excellent photothermal conversion performance, achieving an absorption rate of over 90% for the full spectrum of sunlight in the 250-2500 nm range. Under irradiation with 1 solar intensity, the material surface temperature rises to 75.6℃ in 1 minute and reaches 80.5℃ in 3 minutes. Simultaneously, under irradiation with 1 solar intensity, the evaporation rate of pure water, simulated seawater (3.5 wt% sodium chloride solution), and 10 wt% sodium chloride solution using the designed evaporator reaches 2.2471 kg·m³, respectively. -2 ·h -1 2.2262 kg·m -2 ·h -1 and 2.1964 kg·m -2 ·h -1 It has a more efficient evaporation rate overall, and its evaporation efficiency is over 92.3%.

[0049] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a modified carbon-based photothermal conversion material, characterized in that, The preparation method includes the following steps: S1. The crushed biomass raw material is subjected to carbonization and grinding to obtain biomass carbon powder; S2. According to the composition ratio of carbon ink, the carbon ink is prepared by ball milling. S3. Mix the carbon ink prepared in step S2 with deionized water and disperse it evenly to obtain an ink dispersion; S4. Immerse the dust-free paper in the ink dispersion until it is completely submerged, and perform ultrasonic-assisted modification treatment to obtain ink-modified dust-free paper. S5. The ink-modified dust-free paper is taken out and dried to obtain the modified carbon-based photothermal conversion material.

2. The preparation method according to claim 1, characterized in that, The biomass raw material is at least one of the following: crop straw, rice husk, wood, bamboo, fruit shell, and algae.

3. The preparation method according to claim 1, characterized in that, The carbonization process involves heating to 350°C at a rate of 1°C / min to 3°C / min under an inert gas atmosphere and holding at that temperature for 30 to 60 minutes; then heating to 650°C to 800°C at a rate of 8°C / min to 10°C / min and holding at that temperature for 1 to 3 hours.

4. The preparation method according to claim 1, characterized in that, The grinding process involves adding the ball to a planetary ball mill at a ball-to-material ratio of (10~15):1 and grinding at a speed of 300r / min~600r / min for 1h~2h.

5. The preparation method according to claim 1, characterized in that, Carbon ink comprises the following raw materials in parts by weight: 9 to 15 parts biomass toner, 1 to 2 parts carboxymethyl hydroxypropyl xanthan gum, 0.5 to 3 parts dispersant, 0.1 to 0.5 parts coupling agent, 1 to 3 parts humectant, 0.1 to 0.5 parts stabilizer, and 0.1 to 3 parts surfactant.

6. The preparation method according to claim 5, characterized in that, In step S2, the ball milling conditions are: a rotation speed of 100 r / min to 500 r / min for 1 h to 2 h.

7. The preparation method according to claim 1, characterized in that, In step S3, the volume ratio of carbon ink to deionized water is (1~5):(10~50).

8. The preparation method according to claim 1, characterized in that, In step S4, the power of the ultrasonic-assisted modification treatment is 100W~500W, and the time is 10min~60min.

9. The preparation method according to claim 1, characterized in that, In step S5, the drying temperature is 60℃~100℃ and the time is 1h~4h.

10. An application of a modified carbon-based photothermal conversion material, characterized in that, The application refers to the application of the modified carbon-based photothermal conversion material prepared by the preparation method according to any one of claims 1 to 8 in a solar interface evaporation system, which is suitable for seawater desalination, wastewater evaporation and concentration or photothermal steam power generation.

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