A solar water evaporator based on photovoltaic crystalline silicon waste and a preparation method and application thereof

Abstract

The application belongs to the technical field of solar water evaporation, and discloses a solar water evaporator based on photovoltaic crystalline silicon waste, a preparation method and application thereof. The preparation method comprises the following steps: (1) adding photovoltaic crystalline silicon waste, a dispersing agent and a base material into water, stirring and uniformly mixing to obtain a suspension; (2) pouring the suspension obtained in step (1) into a mold, and constructing an evaporator precursor with a regular arrangement of ice crystal structure by a directional freezing casting method; (3) removing the ice crystals from the evaporator precursor obtained in step (2) by freeze-drying, and then placing the evaporator precursor into an oven to heat and solidify, so as to obtain the solar water evaporator based on photovoltaic crystalline silicon waste. The preparation method is simple and low in cost, the obtained solar water evaporator has good evaporation performance, and can be applied to the fields of water treatment such as seawater desalination and inorganic wastewater purification.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solar water evaporation, and particularly relates to a solar water evaporator based on photovoltaic crystalline silicon waste as well as a preparation method and application thereof. BACKGROUND

[0002] In recent years, the shortage of fresh water resources as one of the problems that have long plagued water-deficient areas is becoming increasingly serious with the uneven distribution of regional resources and the continuous growth of the global population. Since the middle of the last century, a number of technologies including reverse osmosis, multiple-effect distillation and multi-stage flash evaporation have been invented to realize the desalination of seawater, thereby alleviating the above-mentioned problem of fresh water resource shortage to a certain extent. However, although these seawater desalination technologies have realized large-scale application, they consume a large amount of energy in the long-term production process, and therefore the overall economic benefit of the seawater desalination industry is not high. People have been committed to finding new seawater desalination technologies that are more efficient and less costly. Under such a background, solar water evaporation technology emerges as the times require as a technology that can directly apply solar energy, one of clean energies, to the seawater desalination process and realize the output of desalinated water.

[0003] In the solar water evaporation technology, a functional device capable of receiving sunlight and converting light energy into heat energy for water evaporation to realize the functions of seawater desalination or wastewater purification is called a solar water evaporator, which is usually composed of one or several photothermal materials and matrix materials. Common photothermal materials include nano-metal particles (such as gold nanoparticles, silver nanoparticles, etc.), transition metal compounds (such as copper sulfide, titanium nitride, manganese oxide, etc.), polymer materials (such as polypyrrole, polydopamine, etc.), and carbon materials (such as carbon nanotubes, graphene, reduced graphene oxide, etc.). The combination of photothermal materials with other matrix materials can bring more choices to the internal structure and macroscopic external design of the evaporator. Common matrix materials include various polymer materials such as chitosan, polyvinyl alcohol, gelatin, cellulose, etc. that facilitate the configuration of the evaporator, and various commercial products such as sponge, filter paper, cloth, etc. However, the construction or preparation of many current solar water evaporators still has problems such as high cost of raw materials, complex preparation process, long preparation process, etc., and the evaporation performance of some solar water evaporators is not high, which is difficult to meet the demand of fresh water output. Therefore, the preparation of low-cost, easy-to-prepare high-efficiency solar water evaporators is still one of the challenges faced by the field. SUMMARY

[0004] In view of the shortcomings and deficiencies of the prior art, the primary purpose of the present application is to provide a preparation method of a solar water evaporator based on photovoltaic crystalline silicon waste.

[0005] Another purpose of the present application is to provide a solar water evaporator based on photovoltaic crystalline silicon waste prepared by the above method.

[0006] Another object of the present application is to provide the application of the above-mentioned solar water evaporator based on photovoltaic crystalline silicon waste in water treatment such as seawater desalination and inorganic wastewater purification.

[0007] The object of the present application is achieved by the following technical solutions:

[0008] A preparation method of a solar water evaporator based on photovoltaic crystalline silicon waste, comprising the following preparation steps:

[0009] (1) adding photovoltaic crystalline silicon waste, dispersing agent and matrix material into water and stirring to mix uniformly to obtain a suspension;

[0010] (2) pouring the suspension obtained in step (1) into a mold, and constructing an evaporator precursor with regularly arranged ice crystal structure by directional freeze casting method;

[0011] (3) removing the ice crystals from the evaporator precursor obtained in step (2) by freeze drying, and then placing it in an oven for heating and curing to obtain a solar water evaporator based on photovoltaic crystalline silicon waste.

[0012] Further, the photovoltaic crystalline silicon waste in step (1) is generated in the process of cutting silicon ingot into silicon wafer in the photovoltaic crystalline silicon industry, and its main components include at least one of silicon and silicon carbide; the addition amount of the photovoltaic crystalline silicon waste is 2% to 10% of the mass of the solvent.

[0013] Further, the matrix material in step (1) includes at least one of chitosan and melamine urea formaldehyde resin; the addition amount of the matrix material is 0.5% to 4% of the mass of the solvent.

[0014] Further, the dispersing agent in step (1) includes at least one of acetic acid, chitosan and sodium alginate; the addition amount of the dispersing agent is 1% to 4% of the mass of the solvent.

[0015] Further, the regularly arranged ice crystal structure constructed by directional freeze casting in step (2) is a vertical parallel structure; the cold source used in the directional freeze casting process is liquid nitrogen, the temperature of directional freeze casting is -50 to -80℃, and the time of directional freeze casting is 5 to 10 min.

[0016] Further, the temperature of freeze drying in step (3) is -50 to -60℃, and the time of freeze drying is 24 to 72 h.

[0017] Further, the temperature of heating and curing in step (3) is 100 to 150℃, and the time is 0.5 to 2 h.

[0018] A solar water evaporator based on photovoltaic crystalline silicon waste is prepared by the above method.

[0019] The solar water evaporator can be applied to water treatment such as seawater desalination and inorganic wastewater purification.

[0020] The principle of the present application is that, taking photovoltaic crystalline silicon waste and matrix material as main raw materials, a suspension containing the above-mentioned materials is prepared with the aid of a dispersing agent, and then a regularly arranged ice crystal structure is constructed by directional freezing casting, the ice crystals are removed by freeze-drying to form an ordered porous structure, and then the internal structure of the evaporator is fixed by heating and curing treatment, so that a solar water evaporator based on photovoltaic crystalline silicon waste is finally obtained.

[0021] Compared with the prior art, the present application has the following advantages:

[0022] (1) The present application uses photovoltaic crystalline silicon waste as one of the raw materials for preparing the solar water evaporator, which greatly reduces the preparation cost of the evaporator, and the preparation process such as directional freezing casting, freeze-drying and curing adopted in the present application is easy to implement, and the evaporator preparation process does not require high-temperature and high-pressure equipment, which has the advantages of simple operation and easy popularization.

[0023] (2) The solar water evaporator prepared in the present application can form a specific channel structure inside the evaporator based on directional freezing casting, so as to ensure that the evaporator can obtain sufficient and continuous water supply by relying on these channel structures when performing seawater desalination or inorganic wastewater purification, and at the same time, the local high-concentration salt solution generated on the surface of the evaporator due to water evaporation can flow back into the water body, avoiding the accumulation of salt crystallization on the surface of the evaporator, which can cause the evaporation performance of the evaporator to decrease.

[0024] (3) The main components of the photovoltaic crystalline silicon waste used in the present application include silicon, silicon carbide and the like, which can absorb sunlight and convert it into heat energy for water evaporation in the form of non-radiative relaxation as an indirect band gap semiconductor material. When the photothermal material contains multiple photothermal materials such as silicon and silicon carbide, the different energy band structure characteristics of different materials can improve the frequency and probability of valence band electrons being excited compared with the single energy band structure characteristics of a single material, so that the photothermal conversion capacity of the evaporator is improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The X-ray diffraction (XRD) patterns of different kinds of photovoltaic crystalline silicon waste used in step (1) of Example 1 and Example 2 in the present application, and the corresponding ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectra reflecting the photothermal absorption capacity thereof.

[0026] Figure 2To reflect the cross-section and the top surface of the photovoltaic crystalline silicon waste-based solar water evaporator prepared in Example 1 of the present application after step (3) by scanning electron microscope (SEM) images.

[0027] Figure 3 To reflect the cross-section and the top surface of the photovoltaic crystalline silicon waste-based solar water evaporator prepared in Example 1 of the present application after step (3) by scanning electron microscope (SEM) images. DETAILED DESCRIPTION

[0028] The present application will be further described in conjunction with the examples and the accompanying drawings, but the embodiments of the present application are not limited thereto.

[0029] Example 1

[0030] (1) The photovoltaic crystalline silicon waste with components of silicon and silicon carbide (the mass ratio of silicon to silicon carbide is 1:1), a dispersing agent (including chitosan and acetic acid, the mass ratio is 1:1), and a matrix material (melamine urea formaldehyde resin) were added into a deionized water solvent, and a suspension was obtained after magnetic stirring for 12 h. The addition amount of the photovoltaic crystalline silicon waste was 2% of the mass of the deionized water solvent, the addition amount of the dispersing agent was 4% of the mass of the deionized water solvent, and the addition amount of the matrix material was 4% of the mass of the deionized water solvent.

[0031] (2) The uniformly stirred suspension obtained above was poured into a mold, and a regularly arranged ice crystal structure was constructed in the evaporator by a directional freeze casting method. After all the precursor solution in the mold was solidified, it was transferred to a freeze dryer for freeze drying. The regularly arranged ice crystal structure constructed by the directional freeze casting was a parallel arranged vertical structure. Liquid nitrogen was used as a cold source during the directional freeze casting, the casting temperature was -60°C, and the casting time was 10 min. The freeze drying temperature was -60°C, and the freeze drying time was 72 h.

[0032] (3) The dried sample was taken out and transferred to an oven for curing, and finally a photovoltaic crystalline silicon waste-based solar water evaporator was obtained. The curing temperature was 150°C, and the curing time was 1 h.

[0033] 1. The photovoltaic crystalline silicon waste with components of silicon and silicon carbide used in step (1) of the present example was subjected to phase characterization by an X-ray diffractometer (XRD; Bruker D8 Advance, Germany), and its absorption spectrum was collected by an ultraviolet-visible-near infrared spectrometer (UV-vis-NIR; Nicolet IS10, USA) to analyze its light absorption ability, and the results are shown in Figures a-b. Figure 1 a-b. The curve marked as Example 1 in the figures shows that the photovoltaic crystalline silicon waste has a strong absorption ability in the visible light region. Figure 1As can be seen, the photovoltaic crystalline silicon waste used in this embodiment is composed of silicon and silicon carbide; from Figure 1 As can be seen, the photovoltaic crystalline silicon waste used in this embodiment is composed of silicon and silicon carbide, which has good light absorption capacity.

[0034] 2, the cross-section and the upper surface of the evaporator obtained by step (3) were photographed by scanning electron microscope (SEM; Hitachi S-4800, Japan) to analyze the morphology characteristics, and the results are shown in Figure 2 a-b, respectively. From Figure 2 a can be seen, the solar water evaporator constructed by the steps described in example 1 forms a parallel arrangement of vertical channel structure inside; from Figure 2 b can be seen, the parallel arrangement of vertical channel structure formed inside the solar water evaporator can penetrate the entire evaporator and form a porous structure on its surface. The above-mentioned parallel arrangement of vertical channel structure formed inside the evaporator penetrates the entire evaporator, which can be used as the channel for water transport and high concentration salt solution backflow during the evaporation process of the evaporator, so as to ensure that the evaporator maintains high efficiency and stable evaporation performance during continuous operation.

[0035] 3, the solar water evaporator based on photovoltaic crystalline silicon waste constructed in this embodiment is shown in Figure 3 a, the physical processes contained in the internal structure of the evaporator during the evaporation process are shown in Figure 3 b. In Figure 3 a, the evaporator is placed in the polyethylene foam (EPE foam) on its outer side and below to reduce heat loss. At the same time, the dust-free paper between the two layers of EPE foam can transmit the liquid in the water body source below to the bottom of the evaporator to supply the evaporation process. Figure 3 b describes that the parallel arrangement of vertical channel structure can ensure that the water transport and high salt solution backflow processes during the operation of the evaporator do not interfere with each other, so that the evaporator maintains high efficiency and stable evaporation performance during continuous operation.

[0036] 4, the seawater evaporation performance test and the simulated inorganic wastewater evaporation performance test of the solar water evaporator based on photovoltaic crystalline silicon waste were carried out by using xenon lamp light source (CEL-HXF300) and AM 1.5 filter to simulate sunlight. The seawater used is real seawater obtained from the South China Sea; the simulated inorganic wastewater is prepared by adding 3wt% of FeCl3·6H2O, Cu(NO3)2·3H2O, NiCl2 and ZnCl2 into 500mL of deionized water respectively (the water body used in the following examples and comparative examples is the same as described herein). The test results show that the evaporation rate of the solar water evaporator based on photovoltaic crystalline silicon waste in seawater and simulated inorganic wastewater is 2.41kg·m-2 ·h -1 With 2.38 kg·m -2 ·h -1 .

[0037] 5, in the outdoor real environment of sunny day, the seawater evaporation performance test and the simulation inorganic wastewater evaporation performance test of the photovoltaic crystalline silicon waste based solar water evaporator are carried out, and the evaporation rates are 2.29 kg·m -2 ·h -1 With 2.23 kg·m -2 ·h -1 .

[0038] Example 2

[0039] (1) The photovoltaic crystalline silicon waste with silicon component, dispersant (including chitosan and acetic acid, mass ratio 1:1), and matrix material (melamine urea formaldehyde resin) are added to deionized water solvent, and a suspension is obtained after magnetic stirring for 12 h. The addition amount of the photovoltaic crystalline silicon waste is 2% of the mass of the deionized water solvent, the addition amount of the dispersant is 4% of the mass of the deionized water solvent, and the addition amount of the matrix material is 4% of the mass of the deionized water solvent.

[0040] (2) The uniformly stirred suspension obtained above is poured into a mold, and a regularly arranged ice crystal structure is constructed in the evaporator by directional freeze casting method. After all the precursor solution in the mold is solidified, it is transferred to a freeze dryer for freeze drying. The regularly arranged ice crystal structure constructed by directional freeze casting is a vertically arranged parallel structure. Liquid nitrogen is used as the cooling source during directional freeze casting, the casting temperature is -60°C, and the casting time is 10 min. The freeze drying temperature is -60°C, and the time is 72 h.

[0041] (3) The dried sample is taken out and transferred to an oven for curing, and finally a photovoltaic crystalline silicon waste based solar water evaporator is obtained. The curing temperature is 150°C, and the curing time is 1 h.

[0042] 1, the photovoltaic crystalline silicon waste with silicon component used in step (1) of the embodiment is subjected to phase characterization by X-ray diffractometer (XRD; Bruker D8 Advance, Germany), and its absorption spectrum is collected by ultraviolet-visible-near infrared spectrometer (UV-vis-NIR; Nicolet IS10, USA) to analyze its light-heat conversion ability, and the results are shown in Figure 1 a-b. As shown in the curve marked as Example 2 in a-b, the photovoltaic crystalline silicon waste used in the embodiment has a component of silicon; as shown in the mark of a, the photovoltaic crystalline silicon waste used in the embodiment has a component of silicon; as shown in the mark of b, the photovoltaic crystalline silicon waste used in the embodiment has a component of silicon. Figure 1 Figure 1 ​It can be seen that the light absorption capacity of the photovoltaic crystalline silicon waste with the component of silicon used in this embodiment is poorer than that of the photovoltaic crystalline silicon waste with the components of silicon and silicon carbide in Embodiment 1.

[0043] 2, The indoor and outdoor seawater evaporation rates of the solar water evaporator based on the photovoltaic crystalline silicon waste obtained in this embodiment are 2.13 kg·m -2 ·h -1 and 2.04 kg·m -2 ·h -1 respectively; the indoor and outdoor wastewater evaporation rates are 2.05 kg·m -2 ·h -1 and 1.93 kg·m -2 ·h -1 respectively.

[0044] Embodiment 3

[0045] (1) The photovoltaic crystalline silicon waste with the components of silicon and silicon carbide (wherein the mass ratio of silicon to silicon carbide is 1:1), a dispersing agent (including chitosan and acetic acid, with a mass ratio of 1:1), and a matrix material (melamine urea formaldehyde resin) are added to a deionized water solvent, and a suspension is obtained after magnetic stirring for 12 h. The addition amount of the photovoltaic crystalline silicon waste is 4% of the mass of the deionized water solvent, the addition amount of the dispersing agent is 4% of the mass of the deionized water solvent, and the addition amount of the matrix material is 4% of the mass of the deionized water solvent.

[0046] (2) The uniformly stirred suspension obtained above is poured into a mold, and a regularly arranged ice crystal structure is constructed in the evaporator by a directional freezing casting method. After all the precursor solution in the mold is solidified, it is transferred to a freeze dryer for freeze drying. The regularly arranged ice crystal structure constructed by the directional freezing casting is a vertically arranged parallel structure. Liquid nitrogen is used as the cold source during the directional freezing casting process, the casting temperature is -60°C, and the casting time is 10 min. The freeze drying temperature is -60°C, and the freeze drying time is 72 h.

[0047] (3) The dried sample is taken out and transferred to an oven for curing, and finally a solar water evaporator based on photovoltaic crystalline silicon waste is obtained. The curing temperature is 150°C, and the curing time is 1 h.

[0048] The indoor and outdoor seawater evaporation rates of the solar water evaporator based on the photovoltaic crystalline silicon waste obtained in this embodiment are 2.34 kg·m -2 ·h -1 and 2.24 kg·m -2 ·h -1 respectively; the indoor and outdoor wastewater evaporation rates are 2.27 kg·m -2 ·h -12.14 kg·m -2 ·h -1 .

[0049] Example 4

[0050] (1) Photovoltaic crystalline silicon waste with components of silicon and silicon carbide (wherein the mass ratio of silicon to silicon carbide is 1:1), dispersant (including chitosan and acetic acid, mass ratio 1:1), and matrix material (melamine urea formaldehyde resin) were added to a deionized water solvent, and a suspension was obtained after magnetic stirring for 12 h. The addition amount of the photovoltaic crystalline silicon waste was 8% of the mass of the deionized water solvent, the addition amount of the dispersant was 4% of the mass of the deionized water solvent, and the addition amount of the matrix material was 4% of the mass of the deionized water solvent.

[0051] (2) The uniformly stirred suspension obtained above was poured into a mold, and a regularly arranged ice crystal structure was constructed by a directional freezing casting method in an evaporator. After all the precursor solution in the mold was solidified, it was transferred to a freeze dryer for freeze drying. The regularly arranged ice crystal structure constructed by directional freezing casting was a vertically arranged parallel structure. Liquid nitrogen was used as the cooling source during directional freezing casting, the casting temperature was -60°C, and the casting time was 10 min. The freeze drying temperature was -60°C, and the freeze drying time was 72 h.

[0052] (3) The dried sample was taken out and transferred to an oven for curing, and finally a solar water evaporator based on photovoltaic crystalline silicon waste was obtained. The curing temperature was 150°C, and the curing time was 1 h.

[0053] The indoor and outdoor seawater evaporation rates of the solar water evaporator based on photovoltaic crystalline silicon waste obtained in this example were 2.06 kg·m -2 ·h -1 and 1.95 kg·m -2 ·h -1 , respectively. The indoor and outdoor wastewater evaporation rates were 1.99 kg·m -2 ·h -1 and 1.84 kg·m -2 ·h -1 , respectively.

[0054] Comparative Example 1

[0055] In this comparative example, no effective photothermal material was included in the solar water evaporator prepared compared with Example 1, i.e., the evaporator only contained dispersant and matrix material, and the specific steps were as follows:

[0056] (1) Add dispersant (including chitosan and acetic acid, mass ratio 1:1) and matrix material (melamine urea formaldehyde resin) into deionized water solvent, and obtain a suspension after magnetic stirring for 12 h. The amount of dispersant added is 4% of the mass of deionized water solvent, and the amount of matrix material added is 4% of the mass of deionized water solvent.

[0057] (2) Pour the above-obtained uniformly stirred suspension into a mold, and build a regularly arranged ice crystal structure by a directional freezing casting method in an evaporator. After all the precursor solution in the mold is solidified, it is transferred to a freeze dryer for freeze drying. The regularly arranged ice crystal structure built by directional freezing casting is a vertically arranged parallel structure. Liquid nitrogen is used as a cold source during directional freezing casting, the casting temperature is -60°C, and the casting time is 10 min. The freeze drying temperature is -60°C, and the freeze drying time is 72 h.

[0058] (3) Take out the dried sample and transfer it to an oven for curing, and finally obtain a solar water evaporator based on photovoltaic crystalline silicon waste. The curing temperature is 150°C, and the curing time is 1 h.

[0059] The indoor and outdoor seawater evaporation rates of the aerogel solar water evaporator obtained in the present comparative example are 1.29 kg·m -2 ·h -1 and 1.11 kg·m -2 ·h -1 , respectively; and the indoor and outdoor wastewater evaporation rates are 1.22 kg·m -2 ·h -1 and 1.08 kg·m -2 ·h -1 , respectively.

[0060] From the comparison results of the present comparative example and Example 1, it can be seen that if no effective photothermal material is added to the solar water evaporator, the evaporator can only rely on the weak light absorption capacity of the matrix material and the dispersant material to produce heat, and the heat production is much lower than that of the evaporator containing photovoltaic crystalline silicon waste as a photothermal material. Therefore, the measured evaporation rates of seawater and wastewater are both low.

[0061] Comparative Example 2

[0062] Compared with Example 1, the present comparative example does not use directional freezing casting to build vertically arranged parallel channels inside the solar water evaporator. The specific steps are as follows:

[0063] (1) The photovoltaic crystalline silicon waste with components of silicon and silicon carbide (the mass ratio of silicon to silicon carbide is about 1:1), a dispersing agent (including chitosan and acetic acid, the mass ratio is 1:1), and a matrix material (melamine urea formaldehyde resin) are added into a deionized water solvent, and a suspension is obtained after magnetic stirring for 12 h. The addition amount of the photovoltaic crystalline silicon waste is 2% of the mass of the deionized water solvent, the addition amount of the dispersing agent is 4% of the mass of the deionized water solvent, and the addition amount of the matrix material is 4% of the mass of the deionized water solvent.

[0064] (2) The suspension is poured into a mold, and then the mold is directly placed in a low-temperature refrigerator for freezing. After the solidification of all the precursor solutions in the mold, the mold is transferred to a freeze dryer for freeze drying. The freeze drying temperature is -60°C, and the freeze drying time is 72 h.

[0065] (3) The dried sample is taken out and transferred to an oven for curing, and finally a solar water evaporator based on photovoltaic crystalline silicon waste is obtained. The curing temperature is 150°C, and the curing time is 1 h.

[0066] The indoor and outdoor seawater evaporation rates of the solar water evaporator based on photovoltaic crystalline silicon waste obtained in the present comparative example are 1.78 kg·m -2 ·h -1 and 1.62 kg·m -2 ·h -1 , respectively, and the indoor and outdoor wastewater evaporation rates are 1.70 kg·m -2 ·h -1 and 1.58 kg·m -2 ·h -1 , respectively.

[0067] It can be seen from the comparison results of the present comparative example and Example 1 that if the parallelly arranged vertical channels are not constructed inside the solar water evaporator, the water transport and the backflow of the high-salt solution on the surface of the evaporator during the evaporation process will be hindered, which leads to the failure of the evaporator to maintain a high-efficiency evaporation process, and thus the measured evaporation rates of seawater and wastewater are both low.

[0068] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples. Any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement modes, and all shall be included in the protection scope of the present application.

Claims

1. A method for preparing a solar water evaporator based on photovoltaic crystalline silicon waste, characterized in that, The preparation steps include the following: (1) Add photovoltaic crystalline silicon waste, dispersant and matrix material to water and stir to mix evenly to obtain a suspension; (2) Pour the suspension obtained in step (1) into a mold and construct an evaporator precursor with a regularly arranged ice crystal structure by directional cryogenic casting method; (3) Remove ice crystals from the evaporator precursor obtained in step (2) by freeze drying, and then heat and solidify it in an oven to obtain a solar water evaporator based on photovoltaic silicon waste; The photovoltaic crystalline silicon waste mentioned in step (1) is generated in the photovoltaic crystalline silicon industry during the process of cutting silicon ingots into silicon wafers, and its composition is silicon or a mixture of silicon and silicon carbide; The regularly arranged ice crystal structure constructed by directional cryogenic casting in step (2) is a vertical parallel structure; the cold source used in the directional cryogenic casting process is liquid nitrogen, the temperature of directional cryogenic casting is -50~-80℃, and the time of directional cryogenic casting is 5~10min.

2. The method for preparing a solar water evaporator based on photovoltaic crystalline silicon waste according to claim 1, characterized in that, The amount of photovoltaic crystalline silicon waste added in step (1) is 2% to 10% of the water mass.

3. The method for preparing a solar water evaporator based on photovoltaic crystalline silicon waste according to claim 1, characterized in that, The matrix material mentioned in step (1) includes at least one of chitosan and melamine urea formaldehyde resin; the amount of matrix material added is 0.5% to 4% of the water mass.

4. The method for preparing a solar water evaporator based on photovoltaic crystalline silicon waste according to claim 1, characterized in that, The dispersant in step (1) includes at least one of acetic acid, chitosan, and sodium alginate; the amount of the dispersant added is 1% to 4% of the water mass.

5. The method for preparing a solar water evaporator based on photovoltaic crystalline silicon waste according to claim 1, characterized in that, The freeze-drying temperature in step (3) is -50~-60℃, and the freeze-drying time is 24~72h.

6. The method for preparing a solar water evaporator based on photovoltaic crystalline silicon waste according to claim 1, characterized in that, The heating and curing temperature in step (3) is 100~150℃ and the time is 0.5~2h.

7. A solar water evaporator based on photovoltaic crystalline silicon waste, characterized in that, It is prepared by the method described in any one of claims 1 to 6.

8. The application of the solar water evaporator according to claim 7 in seawater desalination and inorganic wastewater purification.

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