Hydrophilic substrate and TiN composite photothermal conversion material and preparation method and application thereof

Abstract

The invention discloses a photothermal conversion material compounded by a hydrophilic substrate and TiN as well as a preparation method and application of the photothermal conversion material, and belongs to the technical field of solar photothermal conversion materials. The material comprises a hydrophilic substrate, TiN nanoparticles loaded on the surface of the substrate and asphalt serving as an adhesive, the preparation method comprises the following steps: dipping a substrate in a dipping solution containing asphalt and TiN, draining and drying. The asphalt is used as a TiN adhesive for the first time, the efficient loading of TiN is realized by an impregnation method, and the loading capacity is 14-96%, and the highest loading capacity is 95.8%. The asphalt has bonding and photothermal conversion functions and has a synergistic interaction with TiN, and the evaporation rate reaches 1.028 kgm <-2 > h <-1 >. The loading capacity and the evaporation performance can be further improved by adding a surfactant into the impregnation liquid. The material still keeps an excellent evaporation rate for 1.0 mol / L CaCl2 high-concentration divalent salt wastewater, and the performance is stable for continuous 7 days. The preparation method does not need high-temperature carbonization, freeze drying and surface modification, and is extremely simple in process, low in cost, green and environment-friendly. The material can be applied to the fields of solar-driven interface evaporation, seawater desalination, salt-containing wastewater treatment and the like.

Description

Technical Field

[0001] This invention belongs to the field of solar thermal conversion material technology, specifically relating to a photothermal conversion material based on a hydrophilic substrate and TiN composite, its preparation method, and the application of the material in solar-driven interfacial evaporation, seawater desalination, and saline wastewater treatment. Background Technology

[0002] Solar-driven interfacial photothermal evaporation technology utilizes photothermal materials to absorb solar energy and convert it into heat energy, achieving localized heating and evaporation of water. This technology requires no additional energy consumption and does not rely on large-scale infrastructure, showing broad application prospects in seawater desalination, industrial wastewater treatment, and emergency drinking water supply. The performance of the photothermal evaporation material is the core factor determining the practicality of this technology. Ideal photothermal materials should possess broad-spectrum high absorption, efficient photothermal conversion, good hydrophilicity / water transport properties, stable mechanical and chemical properties, and low cost and ease of large-scale preparation.

[0003] Titanium nitride (TiN) is a ceramic material with surface plasmon resonance effect. It has a broad-spectrum absorption characteristic in the solar spectrum, high photothermal conversion efficiency, and compared with precious metal plasmon materials such as gold and silver, TiN has significantly lower cost and better chemical stability, and has become one of the research hotspots in the field of photothermal evaporation.

[0004] Currently, there are numerous research reports on TiN-based photothermal evaporation materials. For example, CN119075847B discloses a TiN / polyimide aerogel photothermal evaporator, which uses a unidirectional freezing method to construct a polyimide aerogel with vertically interconnected channels as a substrate, loads TiN nanoparticles, and utilizes the Hofmeister effect to enhance the evaporation rate during seawater desalination. However, this method involves multiple complex processes such as polyimide precursor synthesis, unidirectional freezing, freeze-drying, and high-temperature thermal annealing. The high equipment requirements, long preparation cycle, and high energy consumption limit its large-scale production and widespread application.

[0005] CN110398077A discloses a TiN / carbon foam composite bilayer solar vapor generation material, using carbonized natural wood as a substrate and loading TiN nanoparticles via a coating method. While this material exhibits good photothermal evaporation performance, the carbon foam substrate requires high-temperature carbonization treatment (above 320℃), the substrate source is limited by the microstructure of natural wood, and the coating method results in a low loading capacity, making it difficult to achieve efficient utilization of the TiN component.

[0006] CN119711160A and CN116463108A disclose photothermal materials with TiN loaded onto cotton fabric and polyurethane sponge, respectively. CN119711160A uses a spraying method to load TiN onto cotton fabric and modifies it with PDMS and Janus particles to obtain a superhydrophobic surface; its application is for anti-icing / de-icing, not interfacial evaporation. CN116463108A uses a self-assembly method to load polydopamine-coated TiN onto polyurethane sponge, also constructing a superhydrophobic surface with PDMS, for crude oil adsorption. Both patents pursue superhydrophobic properties of the substrate, which contradicts the hydrophilic water transport requirement for interfacial evaporation. Furthermore, the PDMS / PDA modification and self-assembly processes are cumbersome, and they do not involve a technical solution for achieving high TiN loading using inexpensive adhesives.

[0007] In summary, existing TiN-based photothermal materials have the following common technical bottlenecks: (1) The substrate preparation or modification process is complex, energy-intensive, and costly; (2) TiN loading methods are mostly spraying, coating, and self-assembly, which limit the loading capacity and require chemical modifiers such as PDMS and PDA to enhance the bonding force; (3) The material design focuses on superhydrophobic functions, which contradicts the hydrophilicity and efficient water transport performance required for interface evaporation; (4) There is a lack of simple process routes to achieve high loading and strong bonding of TiN on the surface of hydrophilic fabrics with cheap and readily available adhesives.

[0008] Therefore, developing a TiN-based photothermal conversion material with simple preparation process, low cost, adjustable loading, excellent photothermal evaporation performance, and suitability for seawater desalination and wastewater treatment remains an urgent technical problem to be solved in this field. Summary of the Invention

[0009] This invention addresses numerous shortcomings of existing TiN-based photothermal materials in terms of preparation process, loading efficiency, stability in use, and application adaptability. It aims to provide a photothermal conversion material composed of a hydrophilic substrate and TiN, characterized by a simple process, low cost, and environmental friendliness, along with its preparation method. Specifically, the technical problems to be solved include: how to avoid the complex processes of aerogel synthesis, high-temperature carbonization, freeze-drying, high-temperature annealing, PDA coating, and PDMS modification in existing technologies, and achieve efficient TiN loading on the hydrophilic substrate surface in a single impregnation method; how to achieve strong adhesion and long-term stability between TiN and the substrate without expensive adhesives or surface modifications; how to overcome the bottleneck of low loading capacity in spraying and coating methods, achieving a high TiN component loading (>50%) on the hydrophilic substrate surface, and ensuring a wide controllable range of loading capacity; how to maintain efficient and stable photothermal evaporation performance in complex water bodies such as seawater, high-salinity wastewater, and divalent salt wastewater (e.g., CaCl2); and how to achieve a green and environmentally friendly preparation process with readily available raw materials suitable for large-scale production.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: First, the present invention provides a photothermal conversion material composed of a hydrophilic substrate and TiN, the photothermal conversion material comprising a hydrophilic substrate, TiN nanoparticles loaded on the surface of the hydrophilic substrate, and asphalt, wherein the asphalt acts as a binder to adhere the TiN nanoparticles to the surface of the hydrophilic substrate. The photothermal conversion material is prepared by immersing a hydrophilic substrate in an impregnation solution containing asphalt and TiN nanoparticles, followed by draining and drying.

[0011] This invention reveals that asphalt possesses a dual function in this technical solution: firstly, as a binder, its excellent adhesion properties allow TiN nanoparticles to be firmly loaded onto the hydrophilic substrate surface; secondly, asphalt itself has a certain photothermal conversion capacity, forming a synergistic effect with TiN nanoparticles and significantly improving the overall photothermal conversion efficiency of the composite material. Experiments demonstrate that the evaporation rate of the material loaded solely with asphalt (Material 9) is 0.813 kg•m. -2 •h -1 However, after loading the asphalt and TiN composite (material 3), the evaporation rate increased to 1.028 kg•m. -2 •h -1 This is far greater than the simple sum of the effects of the two alone, demonstrating a clear synergistic effect.

[0012] The hydrophilic substrate is at least one of cotton yarn, cotton cloth, or sponge. These hydrophilic substrates are widely available, inexpensive, possess good hydrophilicity and capillary water transport capabilities, and contain active groups such as hydroxyl groups on their surface, allowing them to form a good interfacial bond with asphalt. Experiments show that the cotton yarn substrate, after being loaded with an asphalt-TiN composite, exhibits the most significant improvement in photothermal evaporation performance.

[0013] The mass ratio of asphalt to TiN nanoparticles was 2.5:1 to 4.5:1. Experiments showed that when the mass ratio of asphalt to TiN was too low, the binder content was insufficient, making it difficult for TiN to adhere effectively to the substrate surface, resulting in reduced loading and evaporation rate (materials 6 and 7). When the mass ratio was too high, the relative TiN content decreased, weakening the photothermal conversion capacity. When the mass ratio of asphalt to TiN was 3.25:1, the material exhibited the best overall performance, with a loading of 61.2% and an evaporation rate of 1.028 kg•m³. -2 •h -1 .

[0014] The total loading of TiN nanoparticles and asphalt on the hydrophilic substrate ranges from 14% to 96% by mass. The loading can be controlled over a wide range by adjusting parameters such as the concentration of asphalt and TiN in the impregnation solution and the number of impregnation cycles. Experiments show that the photothermal evaporation rate increases with increasing loading (materials 1-5), and the evaporation rate stabilizes at 1.028-1.072 kg•m when the loading is 61.2%–95.8%. -2 •h -1 High level.

[0015] The photothermal conversion material also contains a surfactant, which is loaded onto the surface of a hydrophilic substrate. The addition of the surfactant significantly reduces the interfacial tension between the asphalt and the hydrophilic substrate, improving the spreadability and permeability of the asphalt on the substrate surface, thereby increasing the loading capacity and bonding strength. Experiments show that adding sodium dodecyl sulfate to the impregnation solution (Material 3) increases the loading capacity from 45.8% (Material 8) to 61.2%, and the evaporation rate from 0.948 kg•m -2 •h -1 Increased to 1.028 kg•m -2 •h -1 .

[0016] The surfactant is sodium dodecyl sulfonate. This surfactant is anionic, with a moderate hydrophilic-lipophilic balance, good compatibility with asphalt systems, and is non-toxic, environmentally friendly, and inexpensive.

[0017] Secondly, the present invention provides a method for preparing the above-mentioned photothermal conversion material, comprising the following steps: (1) Dissolve asphalt and TiN nanoparticles in an organic solvent and mix them evenly to obtain an impregnation solution; (2) Immerse the hydrophilic substrate in the impregnation solution for 20-60 min to load the asphalt-TiN composite onto the substrate surface; (3) Remove the impregnated substrate, drain the excess liquid, and dry it at 50~80℃ for 1~4 h to obtain the photothermal conversion material; Optionally, repeat steps (2) and (3) 1 to 3 times.

[0018] Finally, this invention provides the application of the above-described photothermal conversion material or the photothermal conversion material prepared by the above method in solar-driven interface evaporation.

[0019] The applications include at least one of seawater desalination, saline wastewater treatment, calcium-containing wastewater treatment, and organic dye wastewater treatment.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention is the first to use asphalt as a binder for TiN nanoparticles for the construction of a photothermal functional layer on a hydrophilic substrate surface. Compared with existing technologies such as CN119075847B (polyimide aerogel + unidirectional freezing + thermal annealing), CN110398077A (wood carbonization + coating), and CN116463108A (PDA coating + self-assembly + PDMS modification), this invention does not require complex precursor synthesis, high-temperature carbonization, freeze drying, high-temperature annealing, or surface modification of TiN. The material preparation can be completed in just three steps: "impregnation-draining-drying". The process chain is extremely short, the equipment requirements are low, and the energy consumption is minimal, giving it significant advantages in industrial scale and cost competitiveness.

[0021] (2) Experiments have shown that asphalt itself has a certain photothermal conversion capacity, but its evaporation rate is only 0.813 kg•m -2 •h -1 (Materials 9); TiN itself has excellent photothermal conversion capabilities, but without the assistance of a binder, it cannot be effectively loaded onto a hydrophilic substrate surface. In this invention, after combining the two, the evaporation rate of Material 3 reaches 1.028 kg•m³. -2 •h -1 Compared to asphalt alone (material 9), the efficiency was increased by 26.4%, and compared to the blank group, the efficiency was increased by 39.8%. This synergistic effect has not been reported in the prior art and has outstanding substantial characteristics.

[0022] (3) This invention achieves an ultra-high loading capacity (up to 95.8%) of TiN and asphalt on a hydrophilic substrate surface by combining impregnation with asphalt binder. In the prior art, the TiN loading capacity of spraying, coating, and self-assembly methods is generally low (usually <10%), and it is difficult to achieve a wide range of load control through simple processes. This invention can achieve a wide range of continuously adjustable loading capacity from 14.6% to 95.8% by adjusting parameters such as impregnation solution concentration and number of impregnations, providing a technical basis for the precise optimization of material properties.

[0023] (4) Experiments showed that after adding sodium dodecyl sulfonate to the impregnation solution (material 3), the loading increased from 45.8% (material 8) to 61.2%, an increase of 15.4 percentage points; the evaporation rate increased from 0.948 kg•m -2 •h -1 Increased to 1.028 kg•m -2 •h -1 The improvement rate reached 8.4%. This effect is not obvious to those skilled in the art. In the prior art, surfactants are mostly used in emulsion preparation, dispersion stabilization and other scenarios. This invention is the first to use them to improve the interfacial bonding force between asphalt and hydrophilic fabrics, and has achieved unexpected technical effects.

[0024] (5) In the prior art, the performance degradation of photothermal evaporation materials in high-concentration salt water is a common problem. Although CN119075847B proposes the Hofmeister effect, it only applies to the monovalent NaCl salt system and does not involve divalent salts such as CaCl2 and MgCl2. The material 3 of this invention still achieves an evaporation rate of 0.98 kg•m in a 1.0 mol / L CaCl2 solution. -2 •h -1 The evaporation rate increased by 33.4% (Table 5), proving that it also has excellent treatment capabilities for high-concentration divalent salt wastewater and has a wider range of applications.

[0025] (6) The stability test for 7 consecutive days showed that the material 3 of the present invention maintained a stable evaporation efficiency for calcium-containing wastewater, with no performance degradation. Figure 10 This is due to the strong bonding between the asphalt binder and the hydrophilic substrate, as well as the protective effect of the asphalt coating on the TiN nanoparticles. Compared with technical solutions such as CN119711160A and CN116463108A, which rely on a hydrophobic PDMS layer to protect the photothermal particles, this invention achieves excellent stability without an additional protective layer, further simplifying the process.

[0026] (7) Asphalt is a byproduct of the petroleum industry, with wide availability and low price; hydrophilic substrates such as cotton yarn, cotton cloth, and sponge are all bulk industrial products or natural products; although TiN nanoparticles are synthetic materials, their dosage can be precisely controlled by the loading amount, and the overall material cost is far lower than that of existing technical solutions. In addition, the preparation process of this invention does not require extreme conditions such as high temperature, high pressure, and high-energy radiation, and the solvent can be recycled and reused, which is in line with the concepts of green chemistry and sustainable development.

[0027] In summary, this invention solves the technical challenge of achieving high loading and strong bonding of TiN on hydrophilic substrates with a simplified process and extremely low cost, resulting in excellent photothermal evaporation performance and long-term stability. It has broad application prospects in fields such as high-salinity wastewater treatment and seawater desalination. Compared with existing technologies, this invention differs significantly in multiple dimensions, including technical approach, core components, preparation process, and performance indicators, possessing outstanding substantive features and significant progress. Attached Figure Description

[0028] Figure 1 These are scanning electron microscope images of materials 1-5 prepared in Examples 1-5 of the present invention and comparative material 10.

[0029] Figure 2 These are scanning electron microscope images of materials 6 and 7 prepared in Examples 6 and 7 of the present invention.

[0030] Figure 3These are scanning electron microscope images of materials 8 and 9 prepared in Examples 8 and 9 of the present invention.

[0031] Figure 4 The images show the ultraviolet-visible-near-infrared absorption spectra of materials 1-5 prepared in Examples 1-5 of this invention.

[0032] Figure 5 The images show the ultraviolet-visible-near-infrared absorption spectra of materials 6 and 7 prepared in Examples 6 and 7 of this invention.

[0033] Figure 6 The images show the ultraviolet-visible-near-infrared absorption spectra of materials 8 and 9 prepared in Examples 8 and 9 of this invention, and material 10 in the comparative example.

[0034] Figure 7 This is a graph showing the evolution of the surface temperature of material 3 prepared in Example 3 of the present invention over time under simulated sunlight.

[0035] Figure 8 This is a graph showing the evolution of the surface temperature of the comparative material 10 (pure cotton yarn) under simulated sunlight over time.

[0036] Figure 9 This is a graph showing the evolution of the surface temperature of material 9 (loaded with asphalt only) prepared in Example 9 of the present invention over time under simulated sunlight.

[0037] Figure 10 This is a graph showing the photothermal evaporation effect of material 3 prepared in Example 3 of the present invention on calcium-containing wastewater during a continuous 7-day test. Detailed Implementation

[0038] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise defined, all technical terms and scientific terms used have the same meaning as commonly understood by those skilled in the art.

[0039] I. Material Preparation Example 1: Preparation of Material 1 200 mL of chloroform, 8.67 g of pitch, 0.6 g of sodium dodecyl sulfonate, and 2.67 g of TiN nanoparticles (particle size: 300-500 nm) were placed in a container and stirred to dissolve, thus obtaining an impregnation solution. 2.4 g of cotton yarn was weighed and immersed in the above impregnation solution while stirring, and the impregnation was continued for 30 min. The cotton yarn was removed, excess liquid was drained, and it was dried in a 60℃ oven for 2 h. The mass was measured to be 2.7504 g, and the calculated loading was 14.6%. The resulting sample was named Material 1.

[0040] Example 2: Preparation of Material 2 200 mL of chloroform, 10.4 g of pitch, 0.6 g of sodium dodecyl sulfonate, and 3.2 g of TiN nanoparticles were placed in a container and stirred to dissolve, thus obtaining an impregnation solution. 2.4 g of cotton yarn was weighed and immersed in the impregnation solution while stirring, and the impregnation was continued for 30 min. The cotton yarn was removed, excess liquid was drained, and it was dried in a 60℃ oven for 2 h. The mass was measured to be 3.12 g, and the calculated loading was 30.0%. The resulting sample was named Material 2.

[0041] Example 3: Preparation of Material 3 200 mL of chloroform, 13 g of asphalt, 0.6 g of sodium dodecyl sulfonate, and 4 g of TiN nanoparticles were placed in a container and stirred to dissolve, thus obtaining an impregnation solution. 2.4 g of cotton yarn was weighed and immersed in the impregnation solution while stirring, and the impregnation was continued for 30 min. The cotton yarn was removed, excess liquid was drained, and it was dried in a 60℃ oven for 2 h. The mass was measured to be 3.8688 g, and the calculated loading was 61.2%. The resulting sample was named Material 3.

[0042] Example 4: Preparation of Material 4 200 mL of chloroform, 13 g of pitch, 0.6 g of sodium dodecyl sulfonate, and 4 g of TiN nanoparticles were placed in a container and stirred to dissolve, thus obtaining an impregnation solution. 2.4 g of cotton yarn was weighed and immersed in the impregnation solution while stirring, and the impregnation was continued for 30 min. The cotton yarn was removed, excess liquid was drained, and it was placed in a 60℃ oven to dry for 2 h. The dried cotton yarn was then subjected to the "impregnation-draining-drying" process once more. The mass was measured to be 4.1016 g, and the calculated loading was 70.9%. The resulting sample was named Material 4.

[0043] Example 5: Preparation of Material 5 200 mL of chloroform, 13 g of pitch, 0.6 g of sodium dodecyl sulfonate, and 4 g of TiN nanoparticles were placed in a container and stirred to dissolve, thus obtaining an impregnation solution. 2.4 g of cotton yarn was weighed and immersed in the impregnation solution while stirring, and the impregnation was continued for 30 min. The cotton yarn was removed, excess liquid was drained, and it was placed in a 60℃ oven to dry for 2 h. The "impregnation-draining-drying" process was repeated twice more after drying. The mass was measured to be 4.6992 g, and the calculated loading was 95.8%. The resulting sample was named Material 5.

[0044] Example 6: Preparation of Material 6 200 mL of chloroform, 13 g of bitumen, 0.6 g of sodium dodecyl sulfonate, and 6 g of TiN nanoparticles were placed in a container and stirred to dissolve, obtaining an impregnation solution. 2.4 g of cotton yarn was weighed and immersed in the impregnation solution while stirring, and the impregnation was continued for 30 min. The cotton yarn was removed, excess liquid was drained, and it was dried in a 60℃ oven for 2 h. The mass was measured to be 3.6024 g, and the calculated loading was 50.1%. The resulting sample was named Material 6. In this embodiment, the mass ratio of bitumen to TiN was 2.17:1.

[0045] Example 7: Preparation of Material 7 200 mL of chloroform, 13 g of bitumen, 0.6 g of sodium dodecyl sulfonate, and 8 g of TiN nanoparticles were placed in a container and stirred to dissolve, obtaining an impregnation solution. 2.4 g of cotton yarn was weighed and immersed in the impregnation solution while stirring, and the impregnation was continued for 30 min. The cotton yarn was removed, excess liquid was drained, and it was dried in a 60℃ oven for 2 h. The mass was measured to be 3.6168 g, and the calculated loading was 50.7%. The resulting sample was named Material 7. In this embodiment, the mass ratio of bitumen to TiN was 1.63:1.

[0046] Example 8: Preparation of Material 8 200 mL of chloroform, 13 g of bitumen, and 4 g of TiN nanoparticles were placed in a container and stirred to dissolve, yielding an impregnation solution (surfactant-free). 2.4 g of cotton yarn was weighed and immersed in the impregnation solution while stirring, continuing the stirring and impregnation for 30 min. The cotton yarn was removed, excess liquid was drained, and it was dried in a 60℃ oven for 2 h. The mass was measured to be 3.4992 g, and the calculated loading was 45.8%. The resulting sample was named Material 8.

[0047] Example 9: Preparation of Material 9 200 mL of chloroform, 13 g of bitumen, and 0.6 g of sodium dodecyl sulfonate were placed in a container and stirred to dissolve, yielding an impregnation solution (TiN-free). 2.4 g of cotton yarn was weighed and immersed in the impregnation solution while stirring, and the mixture was stirred and impregnated for 30 min. The cotton yarn was removed, excess liquid was drained, and the yarn was dried in a 60℃ oven for 2 h. The calculated loading was 56.3%, and the resulting sample was named Material 9.

[0048] Comparative Example: Preparation of Material 10 Take commercially available cotton yarn that has not undergone any treatment and name it Material 10 as a blank control.

[0049] The material composition, mass ratio, and load of Examples 1-9 and the comparative examples are summarized in Table 1.

[0050] Table 1 Composition and Load Capacity of Various Materials II. Structural Characterization and Performance Test Results 1. Microscopic morphological characterization Figure 1 These are scanning electron microscope images of materials 1-5 and material 10. Figure 1 As can be seen, the pure cotton yarn (material 10) is woven from cotton fibers with a diameter of approximately 5 μm, exhibiting uniform fiber particle size and a smooth surface. When loaded with 14.6% pitch-TiN composite (material 1), granular substances appear on the surface of the cotton fibers and in the gaps between fibers, indicating the presence of the pitch-TiN composite. When the loading is increased to 30.0% (material 2), a layer of slurry-like substance coats the surface of the cotton fibers, indicating a tight bond between the pitch and the cotton fibers. When the loading is further increased to 61.2% (material 3), 70.9% (material 4), and 95.8% (material 5), the entire cotton fiber bundle is uniformly coated with the pitch-TiN composite, and the coating layer thickens with increasing loading. These results demonstrate that the method described in this invention can achieve efficient loading of the pitch-TiN composite onto the surface of cotton yarn, and that the loading amount corresponds well with the evolution of the microstructure.

[0051] Figure 2 Scanning electron microscope images of materials 6 and 7 are shown. When the mass ratio of bitumen to TiN is reduced (i.e., the relative TiN content is increased), some particulate matter and slurry-like coatings accumulate on the surface of material 6, but the slurry-like matter on the surface of material 7 is significantly reduced, and the lamellar solids are increased. It is speculated that the lamellar solids are aggregates of TiN nanoparticles. The results indicate that too low bitumen content is not conducive to the effective adhesion of TiN, resulting in a decrease in loading (the loading of materials 6 and 7 is only 50.1% and 50.7%, respectively).

[0052] Figure 3 The images show scanning electron microscope (SEM) images of materials 8, 9, and 10. Material 8 was prepared without the surfactant sodium dodecyl sulfate. Its cotton fiber surface exhibited numerous lamellar solids, but the coating was uneven, with a loading of only 45.8%, significantly lower than material 3 (61.2%), which had the same impregnation solution composition but included a surfactant. Material 9 was only loaded with bitumen; the cotton fiber surface was uniformly coated with a paste-like bitumen, and no particulate matter was observed.

[0053] 2. Characterization of light absorption performance Figure 4 The UV-Vis-NIR absorption spectra of materials 1-5 are shown. Materials 1-5 exhibit significant light absorption across the entire wavelength range of 200-1400 nm, with particularly strong absorption in the UV-Vis region (200-800 nm). As the loading increases from 14.6% to 95.8%, the light absorption intensity across the entire wavelength range gradually increases, indicating that the loading of the pitch-TiN composite is a key factor affecting the light absorption capacity of the materials.

[0054] Figure 5 The UV-Vis-NIR absorption spectra of materials 3, 6, and 7 are shown. Under similar loading conditions (61.2% for material 3, 50.1% for material 6, and 50.7% for material 7), the light absorption intensity of material 3 across the entire wavelength range is significantly higher than that of materials 6 and 7. The results indicate that the mass ratio of asphalt to TiN has a significant impact on the light absorption performance of the materials, with the optimal light absorption performance observed when the asphalt:TiN mass ratio is 3.25:1.

[0055] Figure 6 The UV-Vis-NIR absorption spectra of materials 8, 9, and 10 are shown. Pure cotton yarn (material 10) exhibits almost no light absorption across the entire wavelength range. Only material 9, loaded with pitch, shows some light absorption, but it is significantly lower than that of material 3, loaded with pitch-TiN composite. Figure 4 Although no surfactant was added to Material 8, it still had good light absorption capacity, indicating that surfactant is not a necessary condition for achieving light absorption, but its addition can significantly improve the loading and light absorption intensity (Material 3 vs Material 8).

[0056] 3. Characterization of photothermal conversion performance Figure 7 The evolution of the surface temperature of material 3 over time under simulated sunlight irradiation is shown. The surface temperature of material 3 rapidly increased from room temperature to 76.6℃ within 1 minute of irradiation, and then remained stable. The results indicate that the cotton yarn surface loaded with the pitch-TiN composite exhibits excellent photothermal conversion capabilities.

[0057] Figure 8 The evolution of surface temperature of material 10 (pure cotton yarn) over time under simulated sunlight is shown. Within 5 minutes of continuous illumination, the surface temperature of material 10 only rises to 32.2℃, indicating extremely weak photothermal conversion capability.

[0058] Figure 9 The evolution of surface temperature of Material 9 (asphalt-loaded only) under simulated sunlight over time is shown. The surface temperature of Material 9 rises to 56.3℃ within 1.5 min of illumination and then remains around 57℃. The results indicate that asphalt itself possesses a certain photothermal conversion capacity, but it is significantly lower than that of the asphalt-TiN composite (Material 3, 76.6℃), demonstrating that the introduction of TiN produces a significant photothermal synergistic effect.

[0059] 4. Characterization of interfacial photothermal evaporation performance The sample was cut to a suitable size and laid flat on the surface of a container filled with the liquid to be evaporated, thus fixing the effective evaporation area. A xenon lamp was used to simulate a solar light source with an irradiance of 1 kW•m. -2An electronic balance was used to record the mass changes of the system in real time, automatically recording data every 1 minute for 3 consecutive hours. The evaporation rate (kg•m³) was calculated from the slope of the mass-time curve. -2 •h -1 And calculate the evaporation rate increase rate using the following formula: Evaporation rate improvement (%) = (Sample evaporation rate - Blank evaporation rate) / Blank evaporation rate × 100% (1) Comparison of evaporation performance of different materials Under the above experimental conditions, the interfacial photothermal evaporation performance of materials 1 to 10 in calcium-containing wastewater (CaCl2 solution) was tested, and the results are shown in Table 2.

[0060] Table 2. Evaporation effect of different materials on calcium-containing wastewater As shown in Table 2, the evaporation rate of pure cotton yarn (material 10) is only 0.756 kg•m. -2 •h -1 The evaporation rate was slightly higher than that of the control group, indicating that cotton yarn itself has virtually no photothermal conversion capacity. The evaporation rate of material 9, which only had asphalt loaded, was 0.813 kg•m³. -2 •h -1 The improvement rate was 10.6%, proving that asphalt has a certain photothermal conversion effect. The evaporation rate of material 8 loaded with asphalt-TiN composite reached 0.948 kg·m⁻². -2 •h -1 The improvement rate was 29.0%; after further addition of surfactant, the evaporation rate of material 3 increased to 1.028 kg•m -2 •h -1 The improvement rate reached 39.8%. The above results show that: (1) the introduction of TiN significantly improved the photothermal evaporation performance of the material, and asphalt and TiN have a synergistic effect; (2) the addition of surfactant can significantly improve the loading and evaporation rate, which is an effective means to optimize the material performance.

[0061] (2) Effect of loading on evaporation performance Under the condition of a fixed asphalt:TiN mass ratio of 3.25:1, the effect of loading on the evaporation performance of calcium-containing wastewater was investigated, and the results are shown in Table 3.

[0062] Table 3. Effect of Loading Rate on Evaporation Rate of Calcium-Containing Wastewater As shown in Table 3, as the load increased from 14.6% to 95.8%, the evaporation rate increased from 0.967 kg•m -2 •h -1 Gradually increase to 1.072 kg•m -2•h -1 The evaporation rate increased from 31.5% to 45.8%. The results indicate that, within the mass ratio range described in this invention, increasing the loading of the asphalt-TiN composite is an effective way to enhance photothermal evaporation performance.

[0063] (3) Effect of the mass ratio of asphalt to TiN on evaporation performance Under similar loading conditions (50%~62%), the effect of the mass ratio of asphalt to TiN on the evaporation performance of calcium-containing wastewater was investigated, and the results are shown in Table 4.

[0064] Table 4. Effect of the mass ratio of asphalt to TiN on the evaporation rate As shown in Table 4, under similar loading conditions, the evaporation rate was highest (1.028 kg·m³) when the asphalt:TiN mass ratio was 3.25:1. -2 •h -1 The ratio of asphalt to TiN is significantly better than that of 2.16:1 and 1.63:1. The results indicate that excessively low asphalt content is detrimental to the effective adhesion of TiN, leading to a decrease in the utilization rate of photothermal components and a reduction in the evaporation rate. The preferred asphalt:TiN mass ratio of this invention is 2.5:1 to 4.5:1, and more preferably 3.25:1.

[0065] (4) Effect of different salt concentrations on evaporation performance Material 3 was used to investigate its interfacial photothermal evaporation performance for CaCl2 solutions of different concentrations. The results are shown in Table 5.

[0066] Table 5. Evaporation effect of Material 3 on CaCl2 solutions of different concentrations As shown in Table 5, the evaporation rate decreases with increasing CaCl2 solution concentration, but at a high concentration of 1.0 mol / L, the evaporation rate still reaches 0.98 kg•m. -2 •h -1 The evaporation rate was increased by 33.4%. The results indicate that the photothermal conversion material described in this invention also exhibits excellent photothermal evaporation performance for high-concentration divalent salt wastewater, and has a wide range of applications.

[0067] 5. Stability Characterization The sample underwent interfacial photothermal evaporation testing for several consecutive days (7 days), with consistent testing conditions each day. The changes in evaporation rate were observed to evaluate the long-term stability of the material.

[0068] Figure 10The image shows the photothermal evaporation effect of Material 3 on calcium-containing wastewater during a continuous 7-day test. During the 7-day continuous test, the evaporation rate of Material 3 remained stable, and no performance degradation was observed. The results indicate that the photothermal conversion material described in this invention exhibits excellent long-term stability, which is attributed to the strong bonding between the asphalt adhesive and the cotton yarn substrate, as well as the effective protection of the TiN nanoparticles by the asphalt coating layer.

Claims

1. A photothermal conversion material composed of a hydrophilic substrate and TiN, characterized in that, The photothermal conversion material includes a hydrophilic substrate, TiN nanoparticles loaded on the surface of the hydrophilic substrate, and asphalt, wherein the asphalt acts as a binder to adhere the TiN nanoparticles to the surface of the hydrophilic substrate. The photothermal conversion material is prepared by immersing a hydrophilic substrate in an impregnation solution containing asphalt and TiN nanoparticles, followed by draining and drying.

2. The photothermal conversion material according to claim 1, characterized in that, The hydrophilic substrate is at least one of cotton yarn, cotton cloth, or sponge.

3. The photothermal conversion material according to claim 1, characterized in that, The mass ratio of the asphalt to TiN nanoparticles is 2.5:1 to 4.5:

1.

4. The photothermal conversion material according to claim 3, characterized in that, The mass ratio of the asphalt to TiN nanoparticles is 3.25:

1.

5. The photothermal conversion material according to claim 1, characterized in that, The total loading of the TiN nanoparticles and asphalt on the hydrophilic substrate is 14% to 96% by mass.

6. The photothermal conversion material according to claim 5, characterized in that, The total loading of the TiN nanoparticles and asphalt on the hydrophilic substrate is 30%~70%.

7. The photothermal conversion material according to claim 1, characterized in that, The photothermal conversion material also contains a surfactant, which is loaded onto the surface of a hydrophilic substrate.

8. The photothermal conversion material according to claim 7, characterized in that, The surfactant is sodium dodecyl sulfonate.

9. A method for preparing the photothermal conversion material according to any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Dissolve asphalt and TiN nanoparticles in an organic solvent and mix them evenly to obtain an impregnation solution; (2) Immerse the hydrophilic substrate in the impregnation solution for 20-60 min to load the asphalt-TiN composite onto the substrate surface; (3) Remove the impregnated substrate, drain the excess liquid, and dry it at 50~80℃ for 1~4 h to obtain the photothermal conversion material; Optionally, repeat steps (2) and (3) 1 to 3 times.

10. The application of the photothermal conversion material according to any one of claims 1 to 8 or the photothermal conversion material prepared by the method of claim 9 in solar-driven interface evaporation.

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