Composite photovoltaic evaporator for desalination of photovoltaic evaporation of water body and preparation method thereof

Abstract

This invention belongs to the field of photo-evaporation desalination of water, specifically relating to a composite photoevaporator for photo-evaporation desalination and its preparation method. Carbon nanotubes, which possess excellent light absorption and water transport capabilities, are dispersed in biomass materials. Simultaneously, a layer of copper acetate is sprayed onto the surface of the biomass materials containing carbon nanotubes, forming copper particles after carbonization. The photoevaporator prepared by this invention combines metal, carbon nanotubes, and biomass materials, exhibiting contrasting hydrophilic and hydrophobic properties and strong salt resistance.

Description

Technical Field

[0001] This invention belongs to the field of photoevaporation desalination of water, specifically relating to a composite photoevaporator for photoevaporation desalination of water and its preparation method. Background Technology

[0002] Utilizing solar energy to extract freshwater resources from seawater is one of the technologies with the highest potential for efficient development. It is well known that solar energy has advantages such as sustainability, environmental friendliness, and low cost, providing a free heat source for water evaporation. However, due to the dispersed nature of solar energy, low natural photothermal efficiency, and low light absorption rate of water bodies, the demand for efficient photothermal evaporation of water cannot be met. To alleviate these problems, utilizing highly efficient light-absorbing interface materials to effectively convert light energy into heat energy during the photothermal conversion process, thereby improving the local photothermal evaporation efficiency, is an effective strategy.

[0003] With the development of science and technology, more and more biomass materials have been prepared and have high application potential. For example, Wang et al. (Chemical Engineering Journal, 2023.DOI:10.1016 / j.cej.2023.142265.) reported a method for preparing a photoevaporator based on loofah sponge. Chen et al. (Small, 2023, 19(48):n / an / a.DOI:10.1002 / smll.202303908.) demonstrated a cotton-based photoevaporator prepared by Pickering emulsion polymerization. Zhang et al. (Nano Energy, 2020, 78.DOI:10.1016 / j.nanoen.2020.105322.) used a wood photoevaporator with p-toluenesulfonic acid-assisted hydrothermal treatment for photoevaporation. However, these preparation processes are relatively complex and the preparation conditions are also relatively harsh. Summary of the Invention

[0004] This invention mainly provides a composite photoevaporator with opposite hydrophilic and hydrophobic properties and strong salt resistance for photoevaporation of water for desalination, and its preparation method. The specific scheme is as follows: A method for preparing a composite photoevaporator for photoevaporation of water for desalination includes the following steps: adding carbon nanotubes to a biogel and mixing them evenly, and obtaining a hydrogel by ice template method; then performing freeze-drying to obtain an aerogel base layer; spraying a layer of copper acetate solution onto the upper surface of the base layer, and then performing a second freeze-drying; finally obtaining the composite photoevaporator by carbonization treatment.

[0005] Furthermore, the biogel is made from ice powder seed gum; the carbon nanotubes are multi-walled carbon nanotubes.

[0006] Furthermore, the concentration of the carbon nanotubes in the biogel is 12~35 g / L; the copper acetate solution is a saturated solution.

[0007] Furthermore, the mass ratio of copper acetate to biogel in the copper acetate solution is 1:60~125.

[0008] Furthermore, the preparation method of the ice powder seed glue is as follows: soak ice powder seeds in water at a mass ratio of 1:5~10 for 5~20 minutes; then knead repeatedly at 2~8 ℃ until the solution becomes gelatinous and flows slowly, to obtain a light yellow transparent paste-like ice powder seed glue.

[0009] Furthermore, this includes the following steps: a. Carbon nanotubes are rapidly added to a biogel and stirred thoroughly to disperse them evenly. After the biogel is allowed to stand and solidify, it is frozen until the water in the biogel freezes into ice to obtain a hydrogel. The hydrogel is then freeze-dried to obtain an aerogel substrate. b. Prepare a copper acetate solution, then spray it onto the aerogel substrate. After spraying, freeze-dry it again, then heat it to 500~650 ℃ and carbonize it for 1~2 h to obtain a composite photoevaporator.

[0010] Furthermore, the freezing in step a is performed at -18 ℃ for 4 to 18 hours; the freeze-drying temperature in step a is -30 to -70 ℃, and the vacuum degree is not higher than 2 Pa.

[0011] Furthermore, the heating rate described in step b is 1~3 °C / min.

[0012] A composite photoevaporator for desalination of water prepared by the above-described method includes a hydrophilic base layer and a hydrophobic metal surface layer covering the surface of the base layer.

[0013] Furthermore, it absorbs light across the entire wavelength range; the light absorption rate is not less than 95%.

[0014] By adopting the above scheme, the method of the present invention has the following advantages: The ice powder seeds of this invention, as a common renewable biomass energy source in nature, produce a gel with good biocompatibility and easily adjustable water transport channels. Compared with non-biomass gels, it also has the characteristics of being renewable and non-toxic. At the same time, carbon nanotubes can provide good light absorption and capillary effect, providing a good channel for water transport.

[0015] The copper acetate coating on the surface of the photoevaporator of this invention is carbonized at high temperature to form a Cu layer. Cu exhibits tunable light absorption due to its localized surface plasmon resonance effect. When Cu is irradiated by sunlight, its energy is equivalent to that of a bandgap photon, generating electron-hole pairs. The excited electrons release energy and return to their ground state, simultaneously converting irradiation energy into heat energy, reducing heat loss and promoting heat management. The synergistic effect of Cu, with its high thermal conductivity, as an ideal photothermal conversion material, and carbon nanotubes can improve photothermal conversion efficiency and water evaporation rate.

[0016] The hydrophobic copper metal layer on the surface of the composite evaporator of this invention prevents interference from excessive water wetting, ensuring the dryness of the photothermal conversion interface. Simultaneously, the biomass matrix incorporating carbon nanotubes is hydrophilic. Together, these properties ensure sufficient moisture to reach the photothermal conversion interface during evaporation, exhibiting asymmetric wettability and maintaining stable heat exchange at the biomass-metal layer interface, thus reducing heat loss.

[0017] The capillary action of carbon nanotubes in the base layer of the composite evaporator of this invention provides a transport channel for salt ions during evaporation. While the local salt concentration at the water-air interface increases, the salt ions can diffuse back into the bulk water phase through capillary action, thus inhibiting salt crystallization on the evaporator surface. Simultaneously, the biomass material, as a poor conductor of heat, prevents heat loss downwards, achieving a heat accumulation effect.

[0018] The composite evaporator of this invention has a light absorption rate of up to 98%, exhibiting absorption of sunlight across the entire wavelength range, maintaining a stable evaporation rate, and having a long service life. Attached Figure Description

[0019] Figure 1 This is a scanning electron microscope image of the composite photoevaporator synthesized in Example 1.

[0020] Figure 2 This is a scanning electron microscope image of the aerogel substrate synthesized in step 2 of Example 1.

[0021] Figure 3 This is a scanning electron microscope image of the composite photoevaporator synthesized in step 3 of Example 1.

[0022] Figure 4 This is a transmission electron microscope image of the composite photoevaporator synthesized in Example 1.

[0023] Figure 5 This is a transmission electron microscope image of the aerogel substrate synthesized in step 2 of Example 1.

[0024] Figure 6 This is a transmission electron microscope image of the composite photoevaporator synthesized in step 3 of Example 1.

[0025] Figure 7 This is a scanning electron microscope image of the composite photoevaporator synthesized in Comparative Example 7.

[0026] Figure 8 This is a scanning electron microscope image of the composite photoevaporator synthesized in Comparative Example 8.

[0027] Figure 9 The images show the light absorption curves of the composite photoevaporator synthesized in Example 1 and Comparative Examples 9-11.

[0028] Figure 10 This is a thermal imaging temperature rise diagram of the composite photoevaporator synthesized in Example 1.

[0029] Figure 11 This is a graph showing the mass loss-time curve of pure water evaporation in the composite photoevaporator synthesized in Example 1.

[0030] Figure 12 This is a comparison chart of the evaporation rates of the composite photoevaporator synthesized in Example 1 at different brine concentrations.

[0031] Figure 13 This is a diagram showing the continuous evaporation rate of the composite photoevaporator synthesized in Example 1.

[0032] Figure 14 Pure water evaporation time-temperature curves of the composite photoevaporators synthesized in Example 1 and Comparative Examples 1-3.

[0033] Figure 15 Pure water evaporation time-evaporation rate curves of the composite photoevaporators synthesized in Example 1 and Comparative Examples 1-3. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1: (1) Take 10 g of ice powder seeds and soak them in 80 mL of deionized water at 2~8℃ for 8 minutes. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0036] (2) Add 1.5 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 12 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0037] (3) Dissolve 1 g of copper acetate in 80 mL of deionized water to prepare a saturated solution, and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again, and finally raise the temperature to 600 °C at 1.5 °C / min and keep it at the temperature for 90 min to obtain the composite photoevaporator (Cu@CNTs-IP).

[0038] Depend on Figure 1 and Figure 3 The scanning electron microscope images show that the sample has a layered structure, and the surface of the layers is loaded with uniform copper particles formed after carbonization. Figure 2 Carbon nanotubes are visible, evenly distributed on the layered structure.

[0039] Figure 4 and Figure 6 The transmission electron microscope images show that the copper particles are uniform in size and are evenly distributed with the carbon nanotubes. Figure 5 The presence of carbon nanotubes with a distinct hollow structure indicates that the preparation method of this invention does not damage the morphology of the carbon nanotubes and can support the generation of typical capillary effects.

[0040] Depend on Figure 9 As can be seen from the light absorption curve, the photoevaporator prepared by the method of the present invention can improve the light absorption rate while retaining the characteristic of absorbing sunlight across the entire wavelength range, and the light absorption rate can reach an extremely high 98%. Figure 10 The thermal imaging temperature rise diagram shows that the photoevaporator of the present invention can rapidly heat up to 88.4°C in 180 s under one ray of sunlight, which indicates that it has good light conversion potential.

[0041] Example 2: (1) Take 10 g of ice powder seeds and soak them in 70 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead them to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0042] (2) Add 1.5 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 12 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0043] (3) Dissolve 0.8 g of copper acetate in deionized water to prepare a saturated solution, and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again, and finally heat it to 600 ℃ at 1.5 ℃ / min and keep it at the temperature for 90 min to obtain a composite photoevaporator.

[0044] Example 3: (1) Take 10 g of ice powder seeds and soak them in 80 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0045] (2) Add 1.5 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 6 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0046] (3) Dissolve 1 g of copper acetate in 80 mL of deionized water to prepare a saturated solution, and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again, and finally heat it to 550 °C at 1.5 °C / min and keep it at the temperature for 90 min to obtain the composite photoevaporator.

[0047] Example 4: (1) Take 10 g of ice powder seeds and soak them in 100 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0048] (2) Add 1.5 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 8 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0049] (3) Dissolve 1 g of copper acetate in 80 mL of deionized water to prepare a saturated solution, and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again, and finally raise the temperature to 650 °C at 1.5 °C / min and keep it at the temperature for 90 min to obtain the composite photoevaporator.

[0050] Comparative Example 1: (1) Take 10 g of ice powder seeds and soak them in 50 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain yellow transparent paste-like ice powder seed gelatin.

[0051] (2) Add 1.5 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 4 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0052] (3) Dissolve 0.1 g of copper acetate in 80 mL of deionized water and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again. Finally, heat it to 450 °C at 1.5 °C / min and keep it at that temperature for 90 min to obtain the composite photoevaporator.

[0053] The obtained product had insufficient freezing time, low concentration and quantity of sprayed copper acetate solution, and insignificant local plasma effect, resulting in inadequate photothermal conversion capability and low carbonization temperature. Consequently, the photoevaporator collapsed during the evaporation process.

[0054] Comparative Example 2: (1) Take 10 g of ice powder seeds and soak them in 70 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0055] (2) Add 1.5 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 5 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0056] (3) Dissolve 0.6 g of copper acetate in 80 mL of deionized water and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again. Finally, heat it to 600 °C at 1.5 °C / min and keep it at that temperature for 90 min to obtain the composite photoevaporator.

[0057] The obtained product has a relatively short freezing time and a low concentration of copper acetate solution sprayed on it, resulting in a loose structure of the photoevaporator and a low photothermal conversion efficiency.

[0058] Comparative Example 3: (1) Take 10 g of ice powder seeds and soak them in 100 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0059] (2) Add 1.5 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 8 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0060] (3) Dissolve 0.8 g of copper acetate in 80 mL of deionized water and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again. Finally, heat it to 700 °C at 1.5 °C / min and keep it at that temperature for 90 min to obtain the composite photoevaporator.

[0061] The obtained product exhibits the following issues: due to excessive deionized water added to the copper acetate solution, unsaturated spray concentration, and high carbonization temperature, the surface of the photoevaporator turns gray after carbonization, the edges of the photoevaporator curl, reducing its structural toughness, and causing a decrease in absorbance and a reduction in photothermal conversion efficiency.

[0062] Comparative Example 4: (1) Take 10 g of ice powder seeds and soak them in 80 mL of deionized water at 2~8 ℃ for 3 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0063] (2) Add 0.8 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 12 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0064] (3) Dissolve 1 g of copper acetate in 80 mL of deionized water to prepare a saturated solution, and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again, and finally raise the temperature to 600 °C at 1.5 °C / min and keep it at the temperature for 90 min to obtain the composite photoevaporator.

[0065] The soaking time was too short, which prevented the effective cross-linking components from fully diffusing into the water, reducing the concentration of ice powder seed gum and resulting in poor structural strength of the photoevaporator.

[0066] Comparative Example 5: (1) Take 10 g of ice powder seeds and soak them in 80 mL of deionized water at 15 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0067] (2) Add 0.8 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 12 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0068] (3) Dissolve 1 g of copper acetate in 80 mL of deionized water to prepare a saturated solution, and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again, and finally raise the temperature to 600 °C at 1.5 °C / min and keep it at the temperature for 90 min to obtain the composite photoevaporator.

[0069] The excessively high kneading temperature of the ice powder seeds caused the effective components in the ice powder to be destroyed, reducing the self-polymerization rate and resulting in poor finished product shape from the composite photoevaporator.

[0070] Comparative Example 6: (1) Take 10 g of ice powder seeds and soak them in 80 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0071] (2) Add 0.8 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 12 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0072] (3) Dissolve 1 g of copper acetate in 80 mL of deionized water to prepare a saturated solution, and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again, and finally raise the temperature to 600 °C at 1.5 °C / min and keep it at the temperature for 90 min to obtain the composite photoevaporator.

[0073] If the mass of carbon nanotubes is too small, the light absorption and capillary effect of the photoevaporator will be reduced, resulting in low photothermal conversion efficiency.

[0074] Comparative Example 7: (1) Take 10 g of ice powder seeds and soak them in 80 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0075] (2) Add 2 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 12 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0076] (3) Dissolve 1 g of copper acetate in 80 mL of deionized water to prepare a saturated solution, and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again, and finally raise the temperature to 600 °C at 1.5 °C / min and keep it at the temperature for 90 min to obtain the composite photoevaporator.

[0077] Depend on Figure 7 It is evident that excessive mass of carbon nanotubes leads to aggregation, which in turn clogs the water transport channels and reduces the water transport rate.

[0078] Comparative Example 8: (1) Take 10 g of ice powder seeds and soak them in 80 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0079] (2) Add 1.5 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse it evenly, let it stand until it solidifies, and then put it in a -18 ℃ refrigerator for 12 h to obtain hydrogel; after the end, freeze dry it at -50 ℃ and 1 Pa to obtain aerogel.

[0080] (3) Dissolve 1.5 g of copper acetate in 120 mL of deionized water to prepare a saturated solution, and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again, and finally raise the temperature to 600 °C at 1.5 °C / min and keep it at the temperature for 90 min to obtain a composite photoevaporator.

[0081] Depend on Figure 8 It is evident that excessive copper acetate leads to an excessive number of Cu particles, which accumulate and disrupt the moisture transport channels of the material, while also wasting reagents.

[0082] Comparative Example 9: (1) Take 10 g of ice powder seeds and soak them in 80 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0083] (2) After the above-mentioned ice powder seed gum solidifies, it is placed in a -18 ℃ refrigerator for 12 h to obtain hydrogel; after the end, it is freeze-dried at -50 ℃ and 1 Pa to obtain aerogel (IP).

[0084] Comparative Example 10: (1) Take 10 g of ice powder seeds and soak them in 80 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0085] (2) Add 1.5 g of carbon nanotubes to the above ice powder seed gum quickly, stir thoroughly to disperse evenly, let stand until solidify, and then place in a -18 ℃ refrigerator for 12 h to obtain hydrogel; after completion, freeze dry at -50 ℃ and 1 Pa to obtain aerogel (CNTs-IP).

[0086] Comparative Example 11: (1) Take 10 g of ice powder seeds and soak them in 80 mL of deionized water at 2~8 ℃ for 8 min. Then, repeatedly knead the seeds to extract the gelatinous substance until the solution becomes viscous, and obtain a light yellow transparent paste-like ice powder seed gelatin.

[0087] (2) After the above-mentioned ice powder seed gel solidifies, it is placed in a -18 ℃ refrigerator for 12 h to obtain hydrogel; after the end, it is freeze-dried at -50 ℃ and 1 Pa to obtain aerogel.

[0088] (3) Dissolve 1 g of copper acetate in 80 mL of deionized water to prepare a saturated solution, and spray it onto the surface of the above aerogel. After the upper layer is completely covered by the solution, freeze-dry it again, and finally raise the temperature to 600 °C at 1.5 °C / min and keep it at the temperature for 90 min to obtain a composite photoevaporator (Cu-IP).

[0089] Example Sample Testing:

[0090] Photothermal conversion experiments were conducted at an ambient temperature of 25 °C and a humidity of 45%. The prepared composite photoevaporator was placed on a water surface. Samples were irradiated with a xenon lamp (PLS-SXE 300 / 300UV) to simulate sunlight. The mass loss of water during the evaporation process was recorded using an analytical balance (ME 204E, Mettler Toledo, USA), and the temperature of different samples was recorded using an infrared (IR) thermal imager (~0.4 °C measurement error). The water samples were deionized water and 0 wt% ~ 20 wt% NaCl solutions.

[0091] Depend on Figure 11 The mass loss-time curve of pure water evaporation in the composite photoevaporator synthesized in Example 1 shows that as the light intensity increases, the evaporation capacity of Example 1 first increases and then decreases. This proves that when the photoevaporator is irradiated by higher solar intensity, the high temperature generated at its photothermal interface is conducive to the evaporation of liquid water, but at the same time, the heat conduction, heat radiation and heat convection losses on its surface will also increase.

[0092] Figure 12 This is a comparison graph of the evaporation rate of the composite photoevaporator synthesized in Example 1 under different salt concentrations. As the salt concentration increases, the water evaporation rate of the photoevaporator increases, proving that it has good salt resistance. The composite photoevaporator of the present invention has certain practical application capabilities.

[0093] Figure 13 This is a graph showing the continuous evaporation rate of the composite photoevaporator synthesized in Example 1. Photothermal evaporation experiments were conducted for five consecutive days under natural light using a 3.5 wt% sodium chloride solution. As can be seen from the graph, the evaporation rate remained stable throughout the five-day evaporation process, demonstrating that the composite photoevaporator of this invention has a long service life.

[0094] Figure 14 The pure water evaporation time-temperature curves of the composite photoevaporators synthesized in Example 1 and Comparative Examples 1-3 show that during the evaporation process, the surface temperature of Example 1 was consistently higher than that of Comparative Examples 1, 2, and 3, demonstrating that Example 1 had better light absorption and superior photothermal conversion capability.

[0095] Figure 15The evaporation rate curves of pure water evaporation in the composite photoevaporator synthesized in Example 1 and Comparative Examples 1-3 show that the water evaporation rate of Example 1 is higher than that of Comparative Examples 1, 2, and 3 during the evaporation process, which proves that it has a stronger water transport capability and a higher photothermal conversion efficiency.

[0096] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A method for preparing a composite photoevaporator for photoevaporation desalination of water, characterized in that, Includes the following steps: Using ice powder seed gum as a biogel, multi-walled carbon nanotubes were quickly added and stirred thoroughly to disperse them evenly. After solidification, the biogel was frozen using an ice template method until the water in it froze, resulting in a hydrogel. The hydrogel was then freeze-dried to obtain an aerogel base layer. A layer of copper acetate solution was sprayed onto the surface of the aerogel base layer, followed by a second freeze-drying. The temperature was then raised to 500-650℃ and carbonized for 1-2 hours. After high-temperature carbonization, the copper acetate formed a Cu layer, resulting in a composite photoevaporator. The concentration of multi-walled carbon nanotubes in the biogel was 12-35 g / L. The mass ratio of copper acetate to biogel in the copper acetate solution was 1:60-125.

2. The method for preparing the composite photoevaporator for photoevaporation desalination of water according to claim 1, characterized in that, The preparation method of the ice powder seed glue is as follows: soak ice powder seeds in water at a mass ratio of 1:5~10 for 5~20 minutes; then knead repeatedly at 2~8℃ until the solution becomes gelatinous and flows slowly, to obtain a light yellow transparent paste-like ice powder seed glue.

3. The method for preparing the composite photoevaporator for photoevaporation desalination of water according to claim 1, characterized in that, The freezing is performed at -18°C for 4 to 18 hours; the freeze-drying temperature is -30 to -70°C, and the vacuum degree is not higher than 2 Pa.

4. The method for preparing the composite photoevaporator for photoevaporation desalination of water according to claim 1, characterized in that, The heating rate is 1~3℃ / min.

5. A composite photoevaporator for water desalination prepared by the method of claim 1, characterized in that, It includes a hydrophilic base layer and a hydrophobic metallic surface layer covering the surface of the base layer.

6. The composite photoevaporator for water desalination prepared by the method according to claim 5, characterized in that, It absorbs light across the entire wavelength range; the light absorption rate is not less than 95%.

Images