Preparation and application of bionic multilayer sponge solar evaporator

Abstract

The invention discloses a bionic multi-layer solar sponge structure efficient evaporator, and belongs to the field of water resource purification. The preparation method mainly comprises the steps that polyvinyl alcohol PVA is used as a main body material, carbon black is used as a photo-thermal material, triton is used as a foaming agent, uniform and compact foam is formed through high-speed stirring, then mold shaping and drying are conducted, and the multi-layer non-direct-contact type multi-layer sponge solar evaporator, hereinafter referred to as MSSE, is obtained. In a simulated sunlight irradiation experiment, the evaporator has relatively high and stable evaporation efficiency on pure water, simulated sea salt water 3.5 wt% NaCl solution and salt water 10 wt% NaCl solution with higher concentration. Compared with a traditional double-layer evaporator, the double-layer evaporator has the advantages that the evaporation efficiency reaches 3.5 kg.m <-2 >. H <-1 >, the evaporation efficiency is improved by about 30%, the double-layer evaporator can continuously work in the salt water desalination process, the surface of the evaporator is not obviously crystallized, and the double-layer evaporator has excellent stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of water purification, and particularly relates to a biomimetic multilayer sponge solar evaporator and application thereof in promoting water evaporation and collecting fresh water under the driving of solar energy. BACKGROUND

[0002] A solar evaporator is a fresh water extraction product commonly used in the fields of water purification and seawater desalination. Compared with traditional water treatment methods and desalination processes, the solar evaporator mainly utilizes the energy of sunlight to evaporate water molecules, and then collects fresh water through condensation, while simultaneously blocking impurities in the water body. It is a green and environmentally friendly method for extracting fresh water. However, the working efficiency of the solar evaporator is affected by environmental factors such as light intensity, and the efficiency is usually low. In addition, salt crystals are easily produced on the evaporation surface in a certain concentration of salt water, which hinders the evaporation process. In order to improve the efficiency of the solar evaporator, the utilization rate of sunlight, the heat loss in evaporation, and the salt and pollution resistance of the evaporator can be improved by material modification and evaporator structure adjustment.

[0003] Generally, a solar evaporator is composed of a photothermal material and a substrate material. The photothermal material can absorb incident light, excite the internal electrons of the material to produce transition or oscillation, and generate heat. According to the material type, it is usually divided into carbon materials, metal materials, semiconductor materials, and polymer materials, etc. Since the working environment of the solar evaporator is basically natural sunlight or simulated sunlight driving, the photothermal material needs to have high absorption and conversion capacity in the visible light range, and should maintain stability in different salt concentrations, pH values, and other environments. In addition, the substrate material of the solar evaporator, as a component of the overall stable structure of the evaporator, also has certain requirements for its durability and stability. It can be generally divided into metal materials, polymer materials, and biomass materials, etc.

[0004] To improve the working efficiency of solar evaporator, usually from the following aspects: (1) improve the absorption conversion efficiency of evaporator; (2) reduce the heat loss of evaporation surface; (3) improve the salt resistance of evaporator. Among them, the absorption efficiency of evaporator is closely related to the light and heat material and the form of light absorption surface, so it can be improved by light and heat material modification and evaporation surface structure improvement; and the heat loss can be reduced by introducing heat insulation material in the evaporator, reducing the contact between evaporation surface and water body and other ways; regarding the salt resistance of evaporator, the precipitation and crystallization of salt ions on the evaporation surface can be reduced by adjusting the material charge in the evaporator or adopting double structure method. Recently, the development of evaporator with bionic structure has become one of the main trends. First, the bionic internal channel simulating the water absorption and transmission of plants can transport water to the evaporation surface faster and reduce salt absorption. In addition, the evaporation surface similar to part of the biological structure with large specific surface area can also improve the absorption and conversion of sunlight, or avoid the crystallization of salt on the evaporation surface. SUMMARY

[0005] The solar evaporator in the actual application process faces various problems, and a preparation method and application of a multilayer salt-resistant solar evaporator with bionic structure are provided. The multilayer polyvinyl alcohol sponge evaporator is molded by a mold. Polyvinyl alcohol, as a high hydrophilic polymer material, can efficiently transport water molecules to ensure the transmission efficiency in the evaporation process. The three-layer structure simulating roots, stems and leaves not only forms effective isolation between the evaporation surface and the water body to reduce heat loss, but also reduces the conduction of salt and reduces the crystallization of salt on the evaporation surface. The evaporation surface is further improved by adopting a honeycomb structure to improve the internal reflection and absorption of sunlight and provide more evaporation channels. The mass ratio of PVA to carbon black is 100:1, and the best volume ratio of Triton X-100 to water in the mixed sponge system of PVA and carbon black is 1:16 to construct the carbon black evaporation surface of the multilayer evaporator. The multilayer solar evaporator of the present application has the following technical effects: not only has high evaporation efficiency of 3.5 kg·m -2 ·h -1 , but also can work continuously in the process of salt water desalination, and the surface of the evaporator has no obvious crystallization, and has excellent stability. It has significant progress.

[0006] To achieve the above technical purposes, the technical scheme adopted by the present application is as follows: a multi-layer salt-resistant solar evaporator with a bionic structure, which is composed of a water-absorbing layer, a water-transporting channel and an evaporation surface, simulating the root-stem-leaf structure of plant transpiration.

[0007] The present application also provides a preparation method of the multi-layer salt-resistant solar evaporator with the bionic structure, and the preparation steps are as follows:

[0008] (1) disperse PVA solids in hot water to form a uniform and transparent PVA solution;

[0009] (2) add formaldehyde with a mass fraction of 40%, Triton X-100 with a mass fraction of 70% and sulfuric acid with a mass fraction of 50% to the PVA solution obtained in step (1) in sequence, and stir and mix uniformly;

[0010] (3) continuously stir the mixed solution obtained in step (2) at high speed for three minutes;

[0011] (4) pour the PVA foam dispersion system prepared in step (3) into a mold and dry to obtain a base 1, wherein the lower half of the base is a cylinder with a diameter of 4.0 cm and a height of 1.5 cm, and seven cylinders with a diameter of 1.0 cm and a height of 2.0 cm are arranged and distributed in the circumferential direction on the top surface of the base 1;

[0012] (5) weigh a certain amount of carbon black and PVA solids and disperse them in hot water;

[0013] (6) add formaldehyde with a mass fraction of 40%, Triton X-100 with a mass fraction of 70% and sulfuric acid with a mass fraction of 50% to the mixed solution obtained in step (5) in sequence, and stir and mix uniformly;

[0014] (7) continuously stir the mixed solution obtained in step (6) at high speed for three minutes;

[0015] (8) Pour the mixed foam in step (7) into a mold (the mold is a cylindrical mold with a height of 2.0 cm, an inner diameter of 4.5 cm, and a wall thickness of 0.50 cm, and 20 small cylinders with a height of 1.0 cm and a diameter of 0.45 cm are arranged in a circle at the bottom of the mold), then stack the base 1, and dry at 50℃ for three hours to obtain the final product MSSE2; the finished product has a three-layer structure, and due to the evaporation of water during the drying process, some shrinkage is normal, so the top is a black sponge with a honeycomb hole with a diameter of 4.0 cm and a thickness of 0.50 cm, and the honeycomb hole has a diameter of 0.45 cm ， The depth is 0.40 cm, the middle part is seven cylinders with a diameter of 1.0 cm and a height of 2.0 cm, and the bottom part is a cylinder with a diameter of 4.0 cm and a height of 1.5 cm, thereby preparing the evaporator MSSE2.

[0016] Further, the mass of PVA in step (1) is 5g, and the amount of deionized water is 36ml.

[0017] In step (1), the water bath temperature is 95℃, and the stirring time is two hours.

[0018] In step (2), the amounts of formaldehyde, triton, and sulfuric acid are 6.0ml, 1.25-3.25mL, and 10mL, respectively.

[0019] In step (2), the stirring speed is 300 revolutions per minute.

[0020] In step (5), the mass of carbon black and polyvinyl alcohol is 0.01-0.1g and 5g, respectively, and the amount of deionized water is 36ml.

[0021] In step (5), the water bath temperature is 95℃, and the stirring time is two hours.

[0022] In step (6), the amounts of formaldehyde, triton, and sulfuric acid are 6.0ml, 1.25-32.25mL, and 10mL, respectively.

[0023] In step (6), the stirring speed is 300 revolutions per minute.

[0024] The solar-driven evaporation conditions are as follows:

[0025] The MSSE evaporator obtained in step (8) is fixed in a circular ring PP foam plastic (inner diameter 4.0 cm, outer diameter 6.0 cm, thickness 2.0 cm) and placed in deionized water or salt water. The light source used for evaporation is a 350W xenon lamp with an AM1.5G filter. The ambient temperature during evaporation is 25℃.

[0026] Beneficial effects:

[0027] (1) In the multilayer solar evaporator of the present application, the main material PVA, as a high hydrophilic polymer material, can efficiently transport water molecules, ensuring the transmission efficiency in the evaporation process. The three-layer structure of the simulated root-stem-leaf is compared with the traditional double-layer structure. The parallel cylindrical channels are introduced between the evaporation surface and the water transport layer, forming a hollow partition to reduce heat loss, and reducing the conduction of salt, reducing the crystallization of salt on the evaporation surface. The honeycomb structure is further improved on the evaporation surface to improve the internal reflection and absorption of sunlight, and to provide more evaporation area. The carbon black evaporation surface of the multilayer evaporator is constructed by selecting the formula of Example 3: the mass ratio of PVA to carbon black is 100:1, and the optimal volume ratio of Triton X-100 to water in the mixed sponge system of PVA and carbon black is 1:16. The multilayer solar evaporator of the present application as a whole achieves the technical effect: not only has a high evaporation efficiency of 3.5kg·m -2 ·h -1 , but also can work continuously in the process of seawater desalination, and the surface of the evaporator has no obvious crystallization, and has excellent stability. The evaporation efficiency of the present application is improved by nearly 30% compared with the traditional double-layer evaporator, which has significant progress.

[0028] (2) The present application prepares a solar evaporator with a loose sponge structure by physically mixing raw materials and then stirring and foaming with a foaming agent Triton X-100.

[0029] (3) The present application uses a template method to shape PVA / carbon black sponge, constructs a complete and orderly three-layer biomimetic structure and channel, simulates the process of plant transpiration and water transport, reduces the heat exchange loss between the evaporation surface and the water body, and avoids the aggregation and crystallization of salt on the evaporation surface.

[0030] (4) Under simulated sunlight intensity (1kW·m -2 ), the evaporation efficiency of pure water is as high as 3.53kg·m -2 ·h -1 , which is more than ten times the evaporation efficiency of pure water alone (0.34kg·m -2 ·h -1 ) under the same conditions. The evaporation efficiency of 3.5wt% salt water (simulated seawater salt concentration) is 3.39kg·m -2 ·h -1, and the evaporator surface has no obvious crystallization. Compared with other evaporators using PVA and carbon black as main materials, the evaporator of the present application has a considerable improvement in evaporation efficiency, has unexpected effects, and has significant progress. In addition, the three-layer biomimetic structure of the present application has a significant improvement in heat insulation and salt resistance. After working for 10h, the surface of example 8 has no obvious crystallization. After working for 1h with 10wt% salt water, the evaporator surface has no obvious crystallization, which proves that the example 8 of the present application not only has a high evaporation efficiency of 3.53kg·m -2 ·h -1 , but also can work continuously in the process of salt water desalination, and has excellent stability.

[0031] (5) The solar evaporator prepared by the method has high hydrophilicity due to the use of the hydrophilic polymer PVA, and has high affinity for water molecules, which promotes the formation of a three-phase distribution of free water-intermediate water-bound water in the evaporator, and reduces the evaporation enthalpy of water. In addition, compared with the traditional double-layer evaporator, the evaporator of the present application has a three-layer biomimetic structure, which not only combines the evaporation layer with a high evaporation specific surface and the water transport layer with high hydrophilicity, but also introduces an intermediate column with a certain height between the evaporation surface and the transmission structure, forming a transmission channel and a heat insulation air layer with a height difference, simulating the transmission process of roots-stems-leaves in plant transpiration, ensuring the effective transmission of water molecules by adsorption and capillary action, reducing the contact between the evaporation surface and the water body, and forming an air layer with lower thermal conductivity between the evaporation surface and the water body, thereby reducing the loss caused by heat conduction and ensuring that the temperature of the evaporation surface is maintained at a relatively high level, thereby improving the evaporation efficiency. Moreover, the three-layer structure of the evaporator also reduces the conduction of salt in the water body in the evaporator by increasing the transmission path, reduces the crystallization of salt on the evaporation surface, and avoids the reduction of efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a synthetic route diagram of the biomimetic multilayer sponge solar evaporator of the present application examples 1-8.

[0033] Figure 2 is a real object diagram of the present application (a) example 1, (b) example 7, (c) example 8.

[0034] Figure 3 is a scanning electron microscope image of the base 1 and the top of the present application example 8.

[0035] Figure 4 is a Fourier infrared spectrum diagram of the bottom base 1 and the top of the present application example 8.

[0036] Figure 5 is an experimental schematic diagram of the evaporation experiment of the present application examples 9-14.

[0037] Figure 6 Figure 1 is the result of the pure water evaporation experiment of the sponge solar evaporator of Example 1-4.

[0038] Figure 7 Figure 3 is the result of the pure water evaporation experiment of the sponge solar evaporator of Example 3, Example 5, Example 6.

[0039] Figure 8 Figure 4 is the result of the pure water evaporation experiment of the sponge solar evaporator of Example 3, Example 7, Example 8.

[0040] Figure 9 Figure 5 is the infrared thermal imaging diagram of the sponge solar evaporator of Example 3, Example 7, Example 8 during the evaporation process.

[0041] Figure 10 Figure 6 is the result of the 3.5wt% brine evaporation experiment of the sponge solar evaporator of Example 3, Example 7, Example 8 (a) and the surface salt crystallization after evaporation (b).

[0042] Figure 11 Figure 7 is the result of the 10wt% brine evaporation experiment of the sponge solar evaporator of Example 3, Example 7, Example 8 (a) and the surface salt crystallization after evaporation (b).

[0043] Figure 12 Figure 8 is the result of the 3.5wt% brine 10h evaporation experiment of the sponge solar evaporator of Example 8 (a) and the surface salt crystallization during the evaporation process (b).

[0044] Figure 13 Figure 9 is the pure water evaporation process diagram of the sponge solar evaporator of Example 8. DETAILED DESCRIPTION

[0045] The present application is further illustrated by the following examples. It should be understood that these examples are intended to be illustrative and not limiting of the scope of the present application.

[0046] Example 1

[0047] (1) According to the preparation process, 0.01g of carbon black, 5.0g of PVA and 36ml of deionized water were mixed in a four-necked flask, and after being heated to 95℃, the stirring was continued for two hours. Figure 1 Preparation process, 0.01g of carbon black, 5.0g of PVA and 36ml of deionized water were mixed in a four-necked flask, and after being heated to 95℃, the stirring was continued for two hours.

[0048] (2) The above solution was transferred to a beaker, and under the condition of continuous stirring at 300rpm, 6.0ml of 40% mass fraction of formaldehyde, 2.25ml of 70% mass fraction of triton and 10ml of 50% mass fraction of sulfuric acid were added in sequence.

[0049] (3) Adjust the rotation speed to 1000 rpm and stir for three minutes.

[0050] (4) Pour the mixed foam into a cylindrical mold and dry at 50 °C for three hours to obtain the final product SSSE1. The product is a black cylindrical body with a height of about 4.0 cm and a diameter of about 4.0 cm.

[0051] Example 2

[0052] (1) According to the preparation process, 0.03 g of carbon black, 5 g of PVA, and 36 ml of deionized water were mixed in a four-necked flask, and after being heated to 95 °C, stirring was continued for two hours. Figure 1 (2) The above solution was transferred to a beaker, and 6.0 ml of 40% mass fraction formaldehyde, 2.25 mL of 70% mass fraction triton, and 10 mL of 50% mass fraction sulfuric acid were added in sequence under the condition of continuous stirring at 300 rpm.

[0053] (3) Adjust the rotation speed to 1000 rpm and stir for three minutes.

[0054] (4) Pour the mixed foam into a cylindrical mold and dry at 50 °C for three hours to obtain the final product SSSE2. The product is a black cylindrical body with a height of about 4.0 cm and a diameter of about 4.0 cm.

[0055] Example 3

[0056] (1) According to the preparation process, 0.03 g of carbon black, 5 g of PVA, and 36 ml of deionized water were mixed in a four-necked flask, and after being heated to 95 °C, stirring was continued for two hours.

[0057] Figure 1 (2) The above solution was transferred to a beaker, and 6.0 ml of 40% mass fraction formaldehyde, 2.25 mL of 70% mass fraction triton, and 10 mL of 50% mass fraction sulfuric acid were added in sequence under the condition of continuous stirring at 300 rpm.

[0058] (3) Adjust the rotation speed to 1000 rpm and stir for three minutes.

[0059] (4) Pour the mixed foam into a cylindrical mold and dry at 50 °C for three hours to obtain the final product SSSE3. The product is a black cylindrical body with a height of about 4.0 cm and a diameter of about 4.0 cm.

[0060] Example 4

[0061] (1) According to the preparation process, 0.03 g of carbon black, 5 g of PVA, and 36 ml of deionized water were mixed in a four-necked flask, and after being heated to 95 °C, stirring was continued for two hours.

[0062] (2) The above solution was transferred to a beaker, and 6.0 ml of 40% mass fraction formaldehyde, 2.25 mL of 70% mass fraction triton, and 10 mL of 50% mass fraction sulfuric acid were added in sequence under the condition of continuous stirring at 300 rpm. Figure 1 ​Preparation procedure, 0.1 g carbon black, 5 g PVA and 36 ml deionized water were mixed in a four-necked flask, heated to 95 °C and stirred for two hours.

[0063] (2) The above solution was transferred to a beaker, 6.0 ml of 40% formaldehyde, 2.25 mL of 70% triton and 10 mL of 50% sulfuric acid were added in turn under the condition of continuous stirring at 300 rpm.

[0064] (3) The stirring speed was adjusted to 1000 rpm and stirred for three minutes.

[0065] (4) The mixed foam was poured into a cylindrical mold and dried at 50 °C for three hours to obtain the final product SSSE4. The product was a black cylindrical body with a height of about 4.0 cm and a diameter of about 4.0 cm.

[0066] Example 5

[0067] (1) According to the preparation procedure, 0.05 g carbon black, 5 g PVA and 36 ml deionized water were mixed in a four-necked flask, heated to 95 °C and stirred for two hours. Figure 1 Preparation procedure, 0.05 g carbon black, 5 g PVA and 36 ml deionized water were mixed in a four-necked flask, heated to 95 °C and stirred for two hours.

[0068] (2) The above solution was transferred to a beaker, 6.0 ml of 40% formaldehyde, 2.25 mL of 70% triton and 10 mL of 50% sulfuric acid were added in turn under the condition of continuous stirring at 300 rpm.

[0069] (3) The stirring speed was adjusted to 1000 rpm and stirred for three minutes.

[0070] (4) The mixed foam was poured into a cylindrical mold and dried at 50 °C for three hours to obtain the final product SSSE4. The product was a black cylindrical body with a height of about 4.0 cm and a diameter of about 4.0 cm.

[0071] Example 6

[0072] (1) According to the preparation procedure, 0.05 g carbon black, 5 g PVA and 36 ml deionized water were mixed in a four-necked flask, heated to 95 °C and stirred for two hours. Figure 1 Preparation procedure, 0.05 g carbon black, 5 g PVA and 36 ml deionized water were mixed in a four-necked flask, heated to 95 °C and stirred for two hours.

[0073] (2) The above solution was transferred to a beaker, 6.0 ml of 40% formaldehyde, 2.25 mL of 70% triton and 10 mL of 50% sulfuric acid were added in turn under the condition of continuous stirring at 300 rpm.

[0074] (3) The stirring speed was adjusted to 1000 rpm and stirred for three minutes.

[0075] (4) Pour the mixed foam into a cylindrical mold, and dry at 50 °C for three hours to obtain the final product SSSE6. The product is a black cylinder with a height of about 4.0 cm and a diameter of about 4.0 cm.

[0076] Example 7

[0077] (1) According to the preparation process, 5.0 g of PVA was mixed with 36 ml of deionized water in a four-necked flask, and stirred for two hours after being heated to 95 °C. Figure 1 Preparation process, 5.0 g of PVA was mixed with 36 ml of deionized water in a four-necked flask, and stirred for two hours after being heated to 95 °C.

[0078] (2) The above solution was transferred to a beaker, and 6.0 ml of 40% formaldehyde, 2.25 mL of 70% triton X-100, and 10 mL of 50% sulfuric acid were added in sequence under the condition of continuous stirring at 300 rpm.

[0079] (3) The stirring speed was adjusted to 1000 rpm, and stirred for three minutes.

[0080] (4) Pour the mixed foam into a honeycomb mold, and dry at 50 °C for three hours to obtain the base 1. The lower half of the base is a cylinder with a diameter of 4.0 cm and a height of 1.5 cm, and seven cylinders with a diameter of 1.0 cm and a height of 2.0 cm are arranged in a circle on the top surface.

[0081] (5) According to the preparation process, 5.0 g of PVA was mixed with 36 ml of deionized water in a four-necked flask, and stirred for two hours after being heated to 95 °C.

[0082] (6) The above solution was transferred to a beaker, and 6.0 ml of 40% formaldehyde, 2.25 mL of 70% triton X-100, and 10 mL of 50% sulfuric acid were added in sequence under the condition of continuous stirring at 300 rpm.

[0083] (7) The stirring speed was adjusted to 1000 rpm, and stirred for three minutes.

[0084] (8) Pour the mixed foam into a cylindrical mold, and then stack the base 1, and dry at 50 °C for three hours to obtain the final product MSSE1. The finished product is shown in Figure 2 (b), which is a three-layer structure, with a black sponge on the top with a diameter of 4.0 cm and a thickness of 0.50 cm, seven cylinders with a diameter of 1.0 cm and a height of 2.0 cm in the middle, and a cylinder with a diameter of 4.0 cm and a height of 1.5 cm at the bottom.

[0085] Example 8

[0086] (1) According to the preparation process, 5.0 g of PVA was mixed with 36 ml of deionized water in a four-necked flask, and stirred for two hours after being heated to 95 °C. Figure 1Preparation process, 5.0 PVA and 36 ml deionized water were mixed in a four-necked flask, heated to 95°C and stirred for two hours.

[0087] (2) The above solution was transferred to a beaker, 6.0 ml of 40% formaldehyde, 2.25 mL of 70% triton and 10 mL of 50% sulfuric acid were added in turn under the condition of continuous stirring at 300 rpm.

[0088] (3) The stirring speed was adjusted to 1000 rpm, and the mixed foam was obtained after stirring for three minutes.

[0089] (4) The mixed foam was poured into a honeycomb-shaped mold, dried at 50°C for three hours to obtain the base 1. The lower part of the base is a cylinder with a diameter of 4.0 cm and a height of 1.5 cm, and the top surface is arranged in a circle and distributed with seven cylinders with a diameter of 1.0 cm and a height of 2.0 cm.

[0090] (5) 0.05 g of carbon black, 5.0 g of PVA and 36 ml of deionized water were mixed in a four-necked flask, heated to 95°C and stirred for two hours.

[0091] (6) The solution in step (5) was transferred to a beaker, 6.0 ml of 40% formaldehyde, 2.25 mL of 70% triton and 10 mL of 50% sulfuric acid were added in turn under the condition of continuous stirring at 300 rpm.

[0092] (7) The stirring speed was adjusted to 1000 rpm, and the mixed foam was obtained after stirring for three minutes.

[0093] (8) The mixed foam in step (7) was poured into a mold (the mold as a whole is a cylindrical mold with a height of 2.0 cm, an inner diameter of 4.5 cm and a wall thickness of 0.50 cm, and 20 small cylinders with a height of 1.0 cm and a diameter of 0.45 cm are evenly distributed in a circle at the bottom of the mold), and then the base 1 was stacked, and dried at 50°C for three hours. The finished product is a three-layer structure, and due to the evaporation of water during the drying process, there is some shrinkage, so the top is a black honeycomb sponge with a diameter of 4.0 cm and a thickness of 0.50 cm, and the honeycomb hole diameter is 0.45 cm ， Depth is 0.40 cm, the middle part is seven cylinders with a diameter of 1.0 cm and a height of 2.0 cm, and the bottom part is a cylinder with a diameter of 4.0 cm and a height of 1.5 cm, to prepare the evaporator MSSE2; The MSSE2 material prepared in Example 8 was characterized and tested. First, the morphology was tested by scanning electron microscope (SEM), and the results are shown in Figure 3 Figure 3 ​(a) is a scanning electron microscope image of the base 1 without carbon black. It can be seen that the material is rich in microporous structure in the construction of the staggered network, and the micropore size is about 10 μm or so. In Figure 3 (b) is a top scanning electron microscope image. It can be seen that the sample is also rich in microporous structure, and there are carbon black particles distributed.

[0094] Figure 4 The Fourier infrared spectrograms of the base 1 of the bottom and the top two parts of Example 8 are shown. Both of them appear in the PVA hydroxyl stretching vibration peak at 3200-3550 cm -1 , and both appear in the C-O stretching vibration at 1000 cm -1 or so, which is a typical vibration peak of the PVA skeleton. In addition, the carbon black in the top part has generally weak peak intensity, so no prominent peak appears, but in combination with the SEM image of Figure 3 , it can be judged that the carbon black exists in the material.

[0095] Example 9

[0096] Performance test of pure water solar evaporation of Examples 1-4:

[0097] As shown in Figure 5 , the evaporators prepared in Examples 1-4 were fixed in a circular ring PP foam plastic (inner diameter 4.0 cm, outer diameter 6.0 cm, thickness 2.0 cm) and placed in deionized water. The light source used for evaporation was a 350 W xenon lamp with an AM1.5G filter. The ambient temperature during the evaporation process was 25°C.

[0098] As shown in Figure 6 , the evaporation efficiency of pure water of Examples 1-4 under simulated sunlight intensity (1 kW·m -2 ) reached 2.19 kg·m -2 ·h -1 , 2.64 kg·m -2 ·h -1 , 2.93 kg·m -2 ·h -1 , 2.87 kg·m -2 ·h -1 , respectively, among which Example 3 (PVA and carbon black mass ratio 100:1) was the highest efficiency sample under the same conditions, which proved that in the mixed sponge system of PVA and carbon black, the best mass ratio of the two was 100:1.

[0099] Example 1 (PVA to carbon black mass ratio of 500:1) and Example 2 (PVA to carbon black mass ratio of 300:1) have lower light-heat conversion efficiency because of the too low content of carbon black. Example 4 (PVA to carbon black mass ratio of 50:1) has slightly lower efficiency than Example 3, on the one hand because too much carbon black particles have certain covering and blocking to the evaporation channel, and on the other hand considering the cost factor, the carbon black dosage of Example 3 is already sufficient for application in solar evaporation.

[0100] Example 10

[0101] Performance test of pure water solar evaporation of Example 3, Example 5 and Example 6:

[0102] As shown in Figure 5 , the obtained evaporators prepared by Example 3, Example 5 and Example 6 are fixed with PP foam plastic and placed in deionized water. The light source used for evaporation is a 350W xenon lamp with an AM1.5G filter. The ambient temperature during evaporation is 25℃.

[0103] As shown in Figure 7 , Example 3, Example 5 and Example 6 have an evaporation efficiency of 2.93kg·m -2 ·h -2 ·h -1 ·h -2 ·h -1 ·h -2 ·h -1 respectively under simulated sunlight intensity (1kW·m -2 ). Among them, Example 3 is the sample with the highest efficiency under the same conditions. In Example 5, the volume ratio of Triton X-100 to water is 1:29, and because the amount of Triton X-100 used is too small, the sponge pores formed are relatively dense, which is not conducive to water transmission. In Example 6, the volume ratio of Triton X-100 to water is 1:11, and the sponge pores formed are larger and looser, resulting in higher water content in the evaporator and greater heat loss. It is proved that in the mixed sponge system of PVA and carbon black, the optimal volume ratio of the amount of Triton X-100 to water is 1:16.

[0104] Based on the results of Example 9 and Example 10, the present application selects the formula of Example 3: PVA to carbon black mass ratio of 100:1, and in the mixed sponge system of PVA and carbon black, the optimal volume ratio of the amount of Triton X-100 to water is 1:16, to construct the carbon black evaporation surface of the multi-layer evaporator.

[0105] Example 11

[0106] Performance test of pure water solar evaporation of Example 3, Example 7 and Example 8:

[0107] As shown in Figure 5As shown, the evaporators prepared in Examples 3, 7, and 8 were fixed with PP foam and placed in deionized water. A 350W xenon lamp with an AM1.5G filter was used as the light source for evaporation. The ambient temperature during evaporation was 25°C.

[0108] like Figure 8 As shown, Examples 3, 7, and 8 were performed under simulated solar intensity (1 kW·m²). -2 The evaporation efficiency for pure water reached 2.93 kg·m³. -2 ·h -1 3.15 kg·m -2 ·h -1 3.53 kg·m -2 ·h -1 Example 8 is the most efficient sample under the same conditions. This demonstrates that the three-layer evaporation system constructed in Example 8 of this invention effectively improves evaporation efficiency, and the honeycomb porous design of the evaporation surface further enhances working efficiency. According to... Figure 9 As can be seen from the infrared thermal image, under simulated light intensity, the wetted surface in Example 8 can reach 50.5°C, which is consistent with its highest evaporation efficiency.

[0109] Example 12

[0110] Solar evaporation performance tests of 3.5wt% brine in Examples 3, 7, and 8:

[0111] The evaporators obtained in Examples 3, 7, and 8 were fixed with PP foam and placed in a 3.5 wt% brine solution. A 350W xenon lamp with an AM1.5G filter was used as the light source for evaporation. The ambient temperature during evaporation was 25°C.

[0112] like Figure 10 As shown in (a), Examples 3, 7 and 8 were tested under simulated solar intensity (1 kW·m). -2 The evaporation efficiency for 3.5 wt% brine reached 2.83 kg·m³. -2 ·h -1 2.87 kg·m -2 ·h -1 3.35 kg·m -2 ·h -1 Example 8 is the most efficient sample under the same conditions, and Figure 10 (b) No obvious crystallization was observed on the surfaces of the three evaporators after 1 hour of operation. This is because all three have a loose, sponge-like structure, which provides some resistance to salt crystallization in low-concentration brine.

[0113] Example 13

[0114] Example 3, Example 7 and Example 8 10wt% brine solar evaporation performance test: The obtained Example 3, Example 7 and Example 8 evaporators were fixed with PP foam plastic and placed in 10wt% brine. The light source used for evaporation was a 350W xenon lamp with an AM1.5G filter. The ambient temperature during evaporation was room temperature.

[0115] As shown in Figure 11 (a), Example 3, Example 7 and Example 8 had an evaporation efficiency of 2.51kg·m -2 ·h -2 , 2.82kg·m -1 ·h -2 , 3.08kg·m -1 ·h -2 ·h -1 respectively for 10wt% brine under simulated sunlight intensity (1kW·m Figure 11 (b) shows that after working for 1h, there was no obvious crystallization on the surface of Example 7 and Example 8, while there was obvious salt crystallization on the surface of Example 3. Because the three-layer transmission structure used in Example 7 and Example 8 reduces the direct contact between the evaporation surface and the brine, prolongs the transmission path of the salt in the evaporator, and avoids the excessive transmission and accumulation of the salt.

[0116] Example 14

[0117] Example 8 3.5wt% brine long-time (10h) solar evaporation performance test:

[0118] The Example 8 evaporator was fixed with PP foam plastic and placed in 3.5wt% brine. The light source used for evaporation was a 350W xenon lamp with an AM1.5G filter. The ambient temperature during evaporation was room temperature.

[0119] As shown in Figure 12 (a), Example 8 had an evaporation efficiency of about 3.2kg·m -2 ·h -2 ·h -1 around for 3.5wt% brine under simulated sunlight intensity (1kW·m Figure 12 (b) shows that after working for 10h, there was no obvious crystallization on the surface of Example 8. It is proved that Example 8 of the present application not only has high evaporation efficiency, but also can work continuously in the brine desalination process, and has excellent stability.

Claims

1. A biomimetic multilayer sponge solar evaporator characterized by: The preparation method of the biomimetic multi-layer sponge solar evaporator comprises the following steps: (1) PVA solid is dispersed in hot water to form a uniform transparent PVA solution; (2) To the PVA solution obtained in step (1), 40% by mass formaldehyde, 70% by mass Triton X-100 and 50% by mass sulfuric acid are sequentially added and stirred to mix uniformly; (3) The mixed solution obtained in step (2) is continuously stirred at high speed for three minutes; (4) The PVA foam dispersion system prepared in step (3) is poured into a mold and dried to obtain a base, wherein the lower half of the base is a cylinder with a diameter of 4.0 cm and a height of 1.5 cm, and seven cylinders with a diameter of 1.0 cm and a height of 2.0 cm are uniformly arranged and distributed on the top surface in a circular manner; (5) A certain amount of carbon black and PVA solid are dispersed in hot water; the mass ratio of the mixed sponge system of PVA and carbon black is 100:1; (6) To the mixed solution obtained in step (5), formaldehyde, Triton X-100 and sulfuric acid are sequentially added and stirred to mix uniformly; the best use amount of Triton X-100 and the volume ratio of water are 1:16; (7) The mixed solution obtained in step (6) is continuously stirred at high speed for three minutes to obtain a foam; (8) The foam dispersion system prepared in step (7) is poured into a mold, which is a cylindrical mold, 20 small cylinders with a height of 1.0 cm and a diameter of 0.45 cm are arranged in a circle and evenly distributed at the bottom of the mold, and then a base is stacked, and the final product MSSE2 is obtained by drying at 50°C for three hours. The finished product is a three-layer structure, the top is a black sponge with a diameter of 4.0 cm and a thickness of 0.50 cm, and the honeycomb hole diameter is 0.45 cm ， The depth is 0.40 cm, the middle part is seven cylinders with a diameter of 1.0 cm and a height of 2.0 cm, and the bottom part is a cylinder with a diameter of 4.0 cm and a height of 1.5 cm.

2. The biomimetic multilayer sponge solar evaporator according to claim 1, wherein: In step (1), 5.0 g of PVA and 36 ml of deionized water are placed in a flask, heated to 95°C and continuously stirred for two hours.

3. The biomimetic multilayer sponge solar evaporator according to claim 1, wherein: In the step (2), the use amounts of formaldehyde, Triton X-100 and sulfuric acid are 6.0 mL, 2.25 mL and 10 mL respectively, and the mixing and stirring speed is 300 revolutions / minute.

4. The biomimetic multilayer sponge solar evaporator of claim 1, wherein: In the step (5), the use amounts of PVA and carbon black are 5.0 g and 0.05 g respectively, which are dispersed in 36 ml of deionized water in a 95°C water bath for two hours.

5. The biomimetic multilayer sponge solar evaporator of claim 1, wherein: In the step (6), the use amounts of formaldehyde, Triton X-100 and sulfuric acid are 6.0 mL, 2.25 mL and 10 mL respectively, and the mixing and stirring speed is 300 revolutions / minute.

6. Use of the biomimetic multilayer sponge solar evaporator according to claim 1, characterized in that: The evaporator MSSE obtained in step (8) is fixed with PP foam plastic and placed in pure water or salt water for subsequent evaporation of water.

7. Use of a biomimetic multilayer sponge solar evaporator according to claim 1, characterized in that: The light source used was a 350 W xenon lamp with AM 1.5G filter, with an operating light intensity of 1 kw-m -2 The environment temperature during evaporation was 25℃.

8. Use of a biomimetic multilayer sponge solar evaporator according to claim 1, characterized in that: The preparation method comprises the following steps: (1) 5.0 g of PVA and 36 ml of deionized water are mixed in a four-necked flask, heated to 95°C and continuously stirred for two hours; (2) The above solution is transferred to a beaker, and 6.0 mL of 40% by mass formaldehyde, 2.25 mL of 70% by mass Triton X-100 and 10 mL of 50% by mass sulfuric acid are sequentially added under the condition of continuous stirring at a speed of 300 revolutions / minute; (3) The stirring speed is adjusted to 1000 revolutions / minute, and the mixed foam is obtained after stirring for three minutes; (4) The mixed foam is poured into a honeycomb-shaped mold and dried at 50°C for three hours to obtain a base; the lower half of the base is a cylinder with a diameter of 4.0 cm and a height of 1.5 cm, and seven cylinders with a diameter of 1.0 cm and a height of 2.0 cm are uniformly arranged and distributed on the top surface in a circular manner; (5) 0.05 g of carbon black, 5.0 g of PVA and 36 ml of deionized water are mixed in a four-necked flask, heated to 95°C and continuously stirred for two hours; (6) The solution in step (5) is transferred to a beaker, and 6.0 mL of 40% mass fraction formaldehyde, 2.25 mL of 70% mass fraction triton X-100 and 10 mL of 50% mass fraction sulfuric acid are added in sequence under the condition of a stirring speed of 300 rpm. (7) The stirring speed is adjusted to 1000 rpm, and the mixed foam is obtained after stirring for 3 minutes; (8) Pour the mixed foam in step (7) into a mold, which is a cylindrical mold with a height of 2.0 cm, an inner diameter of 4.5 cm, and a wall thickness of 0.50 cm. Arrange 20 small cylinders with a height of 1.0 cm and a diameter of 0.45 cm uniformly distributed in a circle on the bottom of the mold. Then stack the base and dry at 50°C for three hours to obtain the final product MSSE2. The finished product has a three-layer structure. Due to the evaporation of water during the drying process, some shrinkage is normal. Therefore, the top of the final product is a honeycomb hole black sponge with a diameter of 4.0 cm and a thickness of 0.50 cm, and the honeycomb hole diameter is 0.45 cm ， The depth is 0.40 cm, the middle part is seven cylinders with a diameter of 1.0 cm and a height of 2.0 cm, and the bottom part is a cylinder with a diameter of 4.0 cm and a height of 1.5 cm, thereby preparing an evaporator MSSE2. (9) The evaporator MSSE2 obtained in step (8) is fixed with PP foam plastic, and is placed in pure water or salt water for subsequent water production by evaporation.

Images