Preparation method and application of polypyrrole / hot-pressed melamine sponge aerogel

Abstract

According to the preparation method of the polypyrrole / hot-pressed melamine sponge aerogel provided by the invention, the polypyrrole is loaded on the hot-pressed melamine sponge in situ by utilizing a pyrrole polymerization reaction, the obtained aerogel can fully utilize the excellent optical performance of the polypyrrole and the porous structure of the hot-pressed melamine sponge, and the polypyrrole / hot-pressed melamine sponge aerogel is prepared. The preparation of the polypyrrole / hot-pressed melamine sponge aerogel which is high in mechanical property, super-hydrophilic, low in thermal conductivity and high in photo-thermal conversion efficiency is realized. The polypyrrole / hot-pressed melamine sponge aerogel prepared by the method provided by the invention can be applied to solar evaporation in saline water, actual seawater or heavy metal wastewater so as to obtain a clean water source.

Description

Technical Field

[0001] The present invention relates to the technical field of photothermal materials, and in particular to a preparation method and application of a polypyrrole / hot-pressed melamine sponge aerogel. Background Art

[0002] With the development of human society and economy, the shortage of freshwater resources is becoming increasingly serious. Seawater accounts for 97% of the world's total water resources, while freshwater resources account for approximately 3% of the world's total water resources. However, only 0.3% of the world's freshwater resources are suitable for human use. Traditional freshwater production methods, such as membrane and thermal methods, rely on large fossil fuel consumption and large, centralized facilities, and are associated with high costs and environmental pollution. To reduce the consumption of non-renewable energy, the utilization of clean energy is an inevitable path for human development. Solar energy, with its vast resources, wide distribution, cleanness, and sustainability, offers significant advantages in addressing the current pressing energy crisis and has therefore attracted widespread attention. Solar interfacial photothermal evaporation utilizes highly efficient photothermal materials to absorb solar energy and convert it into heat, which is then used to heat water molecules at the water / air interface to improve water evaporation efficiency. Therefore, solar-driven photothermal evaporation is considered a promising alternative to alleviate freshwater shortages and reduce carbon footprints.

[0003] Existing photothermal materials such as metal nanomaterials are expensive and unstable, and semiconductors and plasma materials usually need to be grown in situ on a substrate, which limits their application. Polypyrrole, as an organic polymer, has excellent solar light absorption rate, photothermal conversion ability, high chemical stability and light density, which provides huge opportunities for the rational design and utilization of photothermal evaporators and is widely used in photothermal evaporation. However, polypyrrole needs to be deposited on a suitable substrate in a suitable manner to achieve the best evaporation effect. In the prior art, the invention patent with application number 201811491923.6 and publication date of August 13, 2021, entitled "A polypyrrole / ZIF-67 composite aerogel and its preparation method" uses the self-polymerization properties of dopamine to modify the polypyrrole aerogel, and then repeatedly soaks the modified polypyrrole aerogel in an organic solution of cobalt nitrate and an organic solution of 2-methylimidazole to obtain a polypyrrole / ZIF-67 composite aerogel. Although polypyrrole composite aerogel can be prepared in the above technical solution, the preparation time is long and it is not environmentally friendly. In addition, in the above technical solution, the polypyrrole aerogel is modified by introducing dopamine, and the polypyrrole aerogel is effectively compounded with ZIF-67, but it is difficult to regulate the internal structure of the aerogel during the preparation process, and the water transmission rate is slow. At the same time, the poor mechanical properties also affect the evaporation effect of the composite aerogel in photothermal evaporation applications. In addition, the invention patent with application number 202110793454.9 and publication date of October 8, 2021, entitled "A Superelastic Solar Interface Evaporation Cellulose Aerogel and Its Preparation Method", utilizes aldehyde cellulose and polyethylene imine to undergo Schiff base reaction and prepare aldehyde cellulose / polyethylene imine aerogel, and the obtained aldehyde cellulose / polyethylene imine aerogel self-polymerizes pyrrole monomer on the surface to prepare aldehyde cellulose / polyethylene imine / polypyrrole aerogel. While the aforementioned technical solution can produce aldehyde-based cellulose / polyethyleneimine / polypyrrole aerogels, the preparation process is cumbersome and costly. Furthermore, while the aforementioned technical solution produces a superelastic aerogel by introducing cellulose, its evaporation performance during photothermal evaporation is low, making it unsuitable for widespread application in photothermal water evaporation wastewater treatment. Therefore, it is necessary to design an improved three-dimensional polypyrrole / hot-pressed melamine sponge aerogel with superior superabsorbency, excellent mechanical properties, and efficient evaporation performance to address these issues. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of polypyrrole / hot-pressed melamine sponge aerogel.

[0005] To achieve the above-mentioned object of the invention, the present invention provides a method for preparing a polypyrrole / hot-pressed melamine sponge aerogel, comprising the following steps: S1, soaking and rinsing the melamine sponge with water and ethanol, placing a heat-conducting iron sheet on the top of the melamine sponge, and placing it in an oven for hot pressing to obtain a hot-pressed melamine sponge; S2, preparing polypyrrole microsphere solution by in situ polymerization; S3, soaking the hot-pressed melamine sponge obtained in step S1 in the solution of step S2 to carry out a polymerization reaction. After the reaction is completed, the obtained gel is rinsed with deionized water until no impurities are precipitated; finally, the three-dimensional gel is processed by a freeze-drying device to obtain a polypyrrole / hot-pressed melamine sponge aerogel.

[0006] Preferably, in step S1, the temperature of the oven is 100-300°C.

[0007] Preferably, in step S1, the hot pressing reaction time is 1 to 10 minutes.

[0008] Preferably, in step S3, the polymerization reaction temperature is 10-50°C.

[0009] Preferably, in step S3, the polymerization reaction time is 12 to 24 hours.

[0010] Preferably, the height of the polypyrrole / hot-pressed melamine sponge aerogel is 0.5-3 cm.

[0011] Preferably, in step S2, the specific preparation process of the polypyrrole microspheres is as follows: a certain amount of P123 and FeCl3·6H2O are added to deionized water to fully dissolve, and then pyrrole is added dropwise to the above solution, and stirred to obtain a mixed solution.

[0012] Preferably, the mass ratio of the P123, the FeCl3·6H2O and the pyrrole is (0.5-1): (0.6-1.3): (0.4-1).

[0013] In particular, the present invention also provides an application of the polypyrrole / hot-pressed melamine sponge aerogel, which is carried out in the following manner: the polypyrrole / hot-pressed melamine sponge aerogel is placed in a water body to be treated, and under simulated sunlight, the temperature and humidity of the environment are kept constant. The change in the sum of the mass of the water body and the polypyrrole / hot-pressed melamine sponge aerogel is monitored by an electronic analytical balance to calculate the sunlight-driven photothermal evaporation rate.

[0014] Preferably, the water body is salt water, actual seawater or heavy metal wastewater.

[0015] The present invention provides a beneficial effect: the method for preparing a polypyrrole / hot-pressed melamine sponge aerogel provided by the present invention first prepares a super-hydrophilic hot-pressed melamine sponge, which is then compounded with polypyrrole to ultimately obtain a hot-pressed melamine sponge with strong mechanical properties, super-hydrophilicity, low thermal conductivity, and high photothermal conversion efficiency. This method effectively solves the problems of complex preparation and high cost associated with conventional aerogel photothermal evaporators. Furthermore, the method can effectively treat salt water, actual seawater, or heavy metal wastewater, thereby producing purified water.

[0016] The polypyrrole / hot-pressed melamine sponge aerogel prepared by the present invention utilizes the hot-pressed melamine sponge with super-hydrophilicity and rich pore structure as the base of the evaporator, which not only gives the composite aerogel super-hydrophilicity, so that when the water body is evaporated, the water is quickly transported to the evaporation interface, and the efficient evaporation of water can be ensured under relatively concentrated light intensity; the excellent optical properties of polypyrrole itself are fully utilized, and the rough surface structure effectively reduces the reflection of incident sunlight, thereby improving the light absorption capacity of the aerogel; the interaction between the porous network structure of the melamine sponge and water is utilized to cause water molecules to evaporate in the form of clusters, thereby reducing water evaporation. The energy required for evaporation is increased, thereby increasing the water evaporation rate; the low thermal conductivity of the composite aerogel can concentrate the heat in the photothermal conversion process at the evaporation interface, reducing the heat exchange with the environment and making it more conducive to the evaporation process; due to the three-dimensional structure of the polypyrrole / hot-pressed melamine sponge aerogel itself, the evaporative cooling effect during the evaporation process makes the temperature of its side lower than the ambient temperature, thereby absorbing additional energy from the environment for the evaporation of water molecules; the three-dimensional structural characteristics are combined with the super hydrophilicity and low evaporation enthalpy of the melamine sponge, giving the polypyrrole / hot-pressed melamine sponge aerogel a high evaporation rate and energy utilization efficiency.

[0017] The polypyrrole / hot-pressed melamine sponge aerogel proposed in the present invention has super-hydrophilicity and rapid water transport, which creates a dynamic balance between salt crystallization and salt release, preventing salt from clogging the internal pores of the aerogel during seawater evaporation and ensuring the continuous evaporation process. The hot-pressed melamine sponge effectively enhances the mechanical strength of the aerogel and improves its practical application performance. The polypyrrole / hot-pressed melamine sponge aerogel also has good purification capabilities for real seawater and heavy metal wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the preparation principle of the polypyrrole / hot-pressed melamine sponge aerogel preparation method of the present invention; Figure 2 This is a SEM image of the polypyrrole / hot-pressed melamine sponge aerogel prepared in Example 1 of the present invention; Figure 3FTIR image of the polypyrrole / hot-pressed melamine sponge aerogel prepared in Example 1 of the present invention; Figure 4 This is a compression strain diagram of the polypyrrole / hot-pressed melamine sponge aerogel prepared in Example 1 of the present invention; Figure 5 This is a graph of the light absorption intensity of the polypyrrole / hot-pressed melamine sponge aerogel prepared in Example 1 of the present invention; Figure 6 This is a differential scanning calorimetry diagram of the polypyrrole / hot-pressed melamine sponge aerogel prepared in Example 1 of the present invention; Figure 7 This is a graph of water transmission rate of the polypyrrole / hot-pressed melamine sponge aerogel prepared in Example 1 of the present invention; Figure 8 This is a graph showing the pure water evaporation rate of polypyrrole / hot-pressed melamine sponge aerogels of different heights prepared in Example 1 of the present invention under 1 sun; Figure 9 This is a graph showing the pure water evaporation rate of the polypyrrole / hot-pressed melamine sponge aerogel prepared in the present invention under 1 sunlight and different wind speeds; Figure 10 This is a graph showing the seawater evaporation rate of the polypyrrole / hot-pressed melamine sponge aerogel prepared in the present invention under 1 sunlight for 7 consecutive days. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] It should also be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0022] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0023] See also Figure 1 As shown, the preparation method of the polypyrrole / hot-pressed melamine sponge aerogel proposed in the present invention comprises the following steps: S1. Preparing a hot-pressed melamine sponge: placing the melamine sponge in an oven and hot-pressing it for several minutes to obtain a hot-pressed melamine sponge; S2. Prepare polypyrrole microsphere solution: add a certain amount of P123 and FeCl3·6H2O into deionized water and stir thoroughly, then add pyrrole dropwise into the above solution and stir to obtain a mixed solution; S3. Preparation of polypyrrole / hot-pressed melamine sponge aerogel: soaking the hot-pressed melamine sponge obtained in step S1 in the solution of step S2 to carry out a polymerization reaction, and rinsing the obtained gel with deionized water until no impurities are precipitated; finally, taking out the three-dimensional gel and treating it with a freeze-drying device to obtain a three-dimensional polypyrrole / hot-pressed melamine sponge aerogel.

[0024] Preferably, in step S1, the temperature of the oven is 100-300°C.

[0025] Preferably, in step S1, the hot pressing reaction time is 1 to 10 minutes.

[0026] Preferably, in step S2, the mass ratio of the P123, the FeCl3·6H2O and the pyrrole is (0.5-1): (0.6-1.3): (0.4-1).

[0027] Preferably, in step S3, the polymerization reaction temperature is 10-50°C.

[0028] Preferably, in step S3, the polymerization reaction time is 12 to 24 hours.

[0029] In particular, the present invention also provides an application method of polypyrrole / hot-pressed melamine sponge aerogel, comprising the following steps: placing a composite aerogel having a length, width, and height of 2 cm and 0.5 to 3 cm in a water body to be treated, maintaining the temperature and humidity of the environment at constant values, irradiating the water body with simulated sunlight, and calculating the sunlight-driven photothermal evaporation rate by monitoring the change in the sum of the mass of the water body and the polypyrrole / hot-pressed melamine sponge aerogel using an electronic analytical balance; the sunlight intensity in the above process is 50 to 300 mW cm -2 , wind speed is 1.5~2.5 ms -1 , the above-mentioned water body is salt water, actual seawater or heavy metal wastewater.

[0030] The preparation method and application of the polypyrrole / hot-pressed melamine sponge aerogel proposed in the present invention are further described below with reference to specific examples:

[0031] Example 1

[0032] This embodiment prepares a polypyrrole / hot-pressed melamine sponge aerogel, including the following preparation steps: S1. Preparing a hot-pressed melamine sponge: placing the melamine sponge in an oven at 230° C. and hot-pressing for 8 minutes to obtain a hot-pressed melamine sponge; S2. Prepare polypyrrole microsphere solution: add 1 g of P123 and 1.26 g of FeCl3·6H2O to deionized water and stir thoroughly. Then, add 0.96 g of pyrrole dropwise to the above solution and stir to obtain a mixed solution. S3. Preparation of polypyrrole / hot-pressed melamine sponge aerogel: soaking the hot-pressed melamine sponge prepared in step S1 in the solution of step S2, performing a polymerization reaction at 25° C. for 24 hours, and rinsing the obtained gel with deionized water until no impurities are precipitated; finally, taking out the three-dimensional gel and treating it with a freeze-drying device to obtain a three-dimensional polypyrrole / hot-pressed melamine sponge aerogel.

[0033] The prepared composite aerogel was characterized, and the obtained spectrum was as follows: Figures 2 to 7 As shown, Figure 2 This is the SEM image of the polypyrrole / hot-pressed melamine sponge aerogel. It can be seen from the figure that the polypyrrole / hot-pressed melamine sponge aerogel has a dense pore size and a three-dimensional curved network structure. In addition, polypyrrole spherical nanoparticles (200~240 nm) are successfully loaded onto the hot-pressed melamine sponge skeleton structure, forming a rough surface, which is conducive to the reflection and absorption of light inside the evaporator. Figure 3 This is the FTIR pattern of polypyrrole / hot-pressed melamine sponge aerogel. The hot-pressed melamine sponge has an FTIR of 3328 cm -1 The absorption peaks at 1540, 1456, 1323, and 812 cm-1 are attributed to the stretching vibrations of -NH- and -OH groups. -1 The transmission peak at 980 cm -1 The absorption peaks of polypyrrole are assigned to the stretching vibrations of CO and NH. The peaks of polypyrrole are located at 1527, 1280, 1140 and 1027 cm -1 The characteristic peaks at are attributed to C-C bending vibration in the pyrrole ring, CN or CH modification in the plane, C-C breathing on the pyrrole ring, and CH deformation and NH deformation vibration. The characteristic peaks of polypyrrole and hot-pressed melamine sponge appear in the polypyrrole / hot-pressed melamine sponge aerogel, indicating that the composite material was successfully prepared. Figure 4 This is the compression strain curve of polypyrrole / hot-pressed melamine sponge aerogel. It can withstand 35 KPa pressure under 50% strain and can completely maintain its original shape after compression without deformation. This shows that polypyrrole / hot-pressed melamine sponge aerogel has excellent mechanical properties, ensuring its applicability under different conditions. Hot pressing can relatively improve the mechanical capacity of melamine sponge. Figure 5This is the light absorption spectrum of polypyrrole / hot-pressed melamine sponge aerogel, which shows a light absorption capacity of more than 97% in the full spectrum range of AM 1.5G. Figure 6 This is the DSC graph of polypyrrole / hot-pressed melamine sponge aerogel. The evaporation enthalpy of polypyrrole / hot-pressed melamine sponge aerogel is 1955 J g -1 , which is much lower than the evaporation enthalpy of pure water (2422 J g -1 ). Figure 7 The water transfer rate diagram of polypyrrole / hot-pressed melamine sponge aerogel shows that when the evaporator height is 3 cm, water can be quickly transported to the top of the evaporator within 19 s, and the water transfer rate is 1.58×10 -3 ms -1 .

[0034] In particular, the present invention also explores the photothermal evaporation performance of the polypyrrole / hot-pressed melamine sponge aerogel. The specific operation steps are as follows: the composite aerogels with heights of 1 cm, 2 cm, and 3 cm, and length and width of 2 cm are placed in pure water, and the intensity is 100 mW cm -2 The evaporation of pure water under simulated sunlight is as follows Figure 8 As shown, the evaporation rates are 1.90, 2.46, and 2.68 kg m -2 h -1 ,The results show that the photothermal evaporation rate is the highest when the height is 3 cm.

[0035] At the same time, the present invention also explored the composite aerogel with a height of 3 cm and a length and width of 2 cm at wind speeds of 1.0, 1.5, 2.0 and 2.5 ms. -1 The photothermal evaporation performance of pure water is 5.45, 6.05, 6.63, and 6.71 kg m -2 h -1 ; At an intensity of 100 mW cm -2 Under simulated sunlight, the concentration of 3.5wt% salt water and 2.5 ms -1 The evaporation rate of the brine was stabilized at 6.20 kg m-3 under continuous operation for 7 days (8 h per day) at the same wind speed. −2 h −1 After the evaporation process is completed, there is no obvious salt crystallization on the surface of the evaporating body and the whole body does not shrink or deform.

[0036] Results show that the polypyrrole / hot-pressed melamine sponge aerogel produced in this invention exhibits high evaporation efficiency and excellent salt tolerance when used for brine evaporation. This is because the porous structure and hydrophilic backbone of the composite aerogel impart super-hydrophilicity, facilitating the transport of brine to the evaporation interface. The optical properties of polypyrrole then convert light energy into heat, thereby evaporating the water in the brine. During the transport and evaporation process, salt crystallization and dissolution in the brine reach a dynamic equilibrium, preventing clogging of the aerogel's pore structure and hindering brine transport to the evaporation interface. Furthermore, the interaction between the network formed by melamine and polypyrrole and water causes water molecules to evaporate in clusters, reducing the energy required for evaporation and thereby increasing the evaporation rate.

[0037] Examples 2 to 4: Examples 2 to 4 differ from Example 1 only in that, in step S1, the melamine sponge is hot-pressed in an oven at 230°C for different periods of time. The other steps are essentially the same as in Example 1 and are not described in detail here. The hot-pressing time settings for the melamine sponge in Examples 2 to 4 are shown in Table 1. The results show that the evaporation rate of the composite aerogel is affected by the hot-pressing time during the preparation of the hot-pressed melamine sponge. A hot-pressing time of 8 minutes achieves the highest evaporation rate for the composite aerogel.

[0038] Table 1 Hot pressing time settings for preparing melamine sponge in Examples 1 to 4 and evaporation rates of the obtained composite aerogels project Hot pressing time (min) <![CDATA[Evaporation rate (kg m -2 h -1 ).]]> Example 1 5 2.16 Example 2 6 2.32 Example 3 7 2.50 Example 4 8 2.68

[0039] Examples 5-6: Examples 5-6 differ from Example 1 only in that the masses of P123, FeCl3·6H2O, and pyrrole are different in step S2. The remaining steps are essentially the same as in Example 1 and are not described here. The mass ratios of P123, FeCl3·6H2O, and pyrrole in Examples 5-6 are shown in Table 2. The results show that the lowest evaporation rate of the composite aerogel was achieved when the mass ratio of P123, FeCl3·6H2O, and pyrrole was 0.5:0.63:0.48.

[0040] Table 2 The mass ratio of P123, FeCl3·6H2O, and pyrrole in the preparation of polypyrrole in Example 1 and Examples 5 to 6 and the evaporation rate of the obtained composite aerogel project <![CDATA[Mass ratio of P123, FeCl3·6H2O, and pyrrole]]> <![CDATA[Evaporation rate (kg m -2 h -1 ).]]> Example 1 1：1.26：0.96 2.68 Example 5 0.5：0.63：0.48 2.24 Example 6 0.75:0.95:0.72 2.59

[0041] Examples 7 and 8: Examples 7 and 8 differ from Example 1 only in the polymerization reaction time in step S3. The other steps are essentially the same as in Example 1 and are not described here. The polymerization reaction time settings in Examples 7 and 8 are shown in Table 3. The results show that the performance of the composite aerogel is affected by the polymerization reaction time during the preparation process, and the evaporation rate of the composite aerogel produced is the highest when the reaction time is 24 hours.

[0042] Table 3 The setting of polymerization reaction time when preparing polypyrrole in Example 1 and Examples 7 to 8 and the evaporation rate of the composite aerogel obtained project Polymerization reaction time <![CDATA[Evaporation rate (kg m -2 h -1 ).]]> Example 1 24 2.68 Example 7 12 2.35 Example 8 36 2.64

[0043] Comparative Example 1 A polypyrrole / ZIF-67 composite aerogel is prepared by the following steps: modifying the polypyrrole aerogel by utilizing the self-polymerization property of dopamine, and then repeatedly immersing the modified polypyrrole aerogel in an organic solution of cobalt nitrate and an organic solution of 2-methylimidazole to obtain a polypyrrole / ZIF-67 composite aerogel.

[0044] In order to compare the photothermal evaporation performance of the polypyrrole / ZIF-67 composite aerogel prepared in Comparative Example 1 and the polypyrrole / hot-pressed melamine sponge aerogel prepared in Example 1, the two were subjected to photothermal water evaporation tests under the same conditions. The results showed that the evaporation rate of the polypyrrole / ZIF-67 composite aerogel was lower than that of the polypyrrole / hot-pressed melamine sponge aerogel. This is because the water transport of the polypyrrole / ZIF-67 composite aerogel is slow and the energy required for the evaporation of water molecules is high.

[0045] Comparative Example 2 A superelastic solar interface evaporated cellulose aerogel and a preparation method thereof, the preparation method comprising the following steps: utilizing aldehyde cellulose and polyethylene imine to undergo a Schiff base reaction to prepare aldehyde cellulose / polyethylene imine aerogel, and self-polymerizing pyrrole monomers on the surface of the prepared aldehyde cellulose / polyethylene imine aerogel to prepare aldehyde cellulose / polyethylene imine / polypyrrole aerogel.

[0046] The cellulose aldehyde / polyethyleneimine / polypyrrole aerogel prepared in Comparative Example 2 and the polypyrrole / hot-pressed melamine sponge aerogel prepared in Example 1 were subjected to photothermal evaporation under the same conditions. The evaporation rate of the composite aerogel prepared in this comparative example was 1.66 kg m -2 h -1 This value is significantly lower than the evaporation rate of 2.68 kg m in Example 1. -2 h -1 The results show that the polypyrrole / hot-pressed melamine sponge aerogel prepared by the method proposed in the present invention can achieve an effective combination of excellent light absorption, super hydrophilicity, low evaporation enthalpy and environmental enhancement, and shows more excellent photothermal conversion.

[0047] In summary, the method for preparing the polypyrrole / hot-pressed melamine sponge aerogel proposed in the present invention utilizes an in-situ polymerization reaction of polypyrrole, which is loaded onto a hot-pressed melamine sponge substrate to produce a composite aerogel. This method fully utilizes the superhydrophilicity of the hot-pressed melamine sponge and the excellent optical properties and high specific surface area of ​​polypyrrole itself, resulting in a polypyrrole / hot-pressed melamine sponge aerogel with strong mechanical properties, superhydrophilicity, low thermal conductivity, and high photothermal conversion efficiency. The porous structure of the hot-pressed melamine sponge not only imparts superhydrophilicity to the composite aerogel, making it easier to transport water to the evaporation interface during photothermal evaporation, but also utilizes the evaporative cooling effect of the three-dimensional evaporator to obtain net energy from the environment, thereby significantly improving the evaporation rate. The polypyrrole / hot-pressed melamine sponge aerogel produced using the method proposed in the present invention can be used to evaporate water molecules from salt water, actual seawater, or heavy metal wastewater to obtain clean water resources.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing polypyrrole / hot-pressed melamine sponge aerogel, characterized in that: The steps include: S1, soaking and rinsing the melamine sponge with water and ethanol, placing a heat-conducting iron sheet on the top of the melamine sponge, and placing it in an oven for hot pressing to obtain a hot-pressed melamine sponge; S2, preparing polypyrrole microsphere solution by in-situ polymerization method; S3, soaking the hot-pressed melamine sponge obtained in step S1 in the solution of step S2 to carry out a polymerization reaction, and after the reaction is completed, washing the obtained gel with deionized water until no impurities are precipitated; finally, the three-dimensional gel is treated by a freeze-drying device to obtain a polypyrrole / hot-pressed melamine sponge aerogel.

2. The method for preparing the polypyrrole / hot-pressed melamine sponge aerogel according to claim 1, characterized in that: In step S1, the temperature of the oven is 100-300°C.

3. The method for preparing the polypyrrole / hot-pressed melamine sponge aerogel according to claim 1, characterized in that: In step S1, the hot pressing reaction time is 1 to 10 min.

4. The method for preparing the polypyrrole / hot-pressed melamine sponge aerogel according to claim 1, characterized in that: In step S3, the polymerization reaction temperature is 10-50°C.

5. The method for preparing polypyrrole / hot-pressed melamine sponge aerogel according to claim 1, characterized in that: In step S3, the polymerization reaction time is 12 to 24 hours.

6. The method for preparing polypyrrole / hot-pressed melamine sponge aerogel according to claim 1, characterized in that: In step S2, the specific preparation process of the polypyrrole microspheres is as follows: a certain amount of P123 and FeCl3·6H2O are added into deionized water to fully dissolve, and then pyrrole is added dropwise into the above solution, and a mixed solution is obtained after stirring.

7. The method for preparing polypyrrole / hot-pressed melamine sponge aerogel according to claim 6, characterized in that: The mass ratio of the P123, the FeCl3·6H2O and the pyrrole is (0.5-1): (0.6-1.3): (0.4-1).

8. An application of the polypyrrole / hot-pressed melamine sponge aerogel prepared according to claims 1 to 7, characterized in that: The method is as follows: polypyrrole / hot-pressed melamine sponge aerogel is placed in a water body to be treated, and under simulated sunlight, the temperature and humidity of the environment are regulated to be constant. The change in the sum of the masses of the water body and the polypyrrole / hot-pressed melamine sponge aerogel is monitored by an electronic analytical balance to calculate the solar-driven photothermal evaporation rate.

9. The use of the polypyrrole / hot-pressed melamine sponge aerogel according to claim 8, wherein the water body is salt water, actual seawater or heavy metal wastewater.

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