Salt-tolerant biomass photo-thermal interface evaporation material as well as preparation method and application thereof

Abstract

The invention discloses a salt-tolerant biomass photo-thermal interface evaporation material as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, peeling fresh cactus, cutting pulp into blocks, putting the blocks into water, and heating at 50-70 DEG C under a stirring condition; s2, the block-shaped cactus pulp obtained after treatment in the step S1 is taken out of water and placed on a heating flat plate, so that one plane of the block-shaped pulp makes contact with the high-temperature heating flat plate until the treated surface becomes a black carbonized layer, and the thickness of the carbonized layer is 0.8-1.2 mm; and S3, uniformly coating the carbonized layer of the cactus pulp with pyrrole, then uniformly coating the carbonized layer coated with pyrrole with an oxidizing agent aqueous solution with the concentration of 50-80 mM, and carrying out full polymerization reaction to obtain the salt-tolerant biomass photo-thermal interface evaporation material, namely polypyrrole (at) cactus. The salt-tolerant biomass photo-thermal interface evaporation material can be applied to solar-driven interface evaporation, photo-thermal seawater desalination and sewage treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of photothermal interface evaporation material preparation, and in particular to a salt-resistant biomass photothermal interface evaporation material and a preparation method and application thereof. Background Art

[0002] Using green, recyclable solar energy as a driving force, an emerging water purification process produces pure water through interfacial water evaporation, showing the characteristics of environmental friendliness and sustainable development. The uniqueness of this technology is that it does not require additional energy input or large-scale construction facilities to facilitate the rapid evaporation of water. In the solar interfacial evaporation method, the core challenge is to ensure that the heat conversion of solar energy is only carried out at the gas-liquid interface, and to maximize the use of the generated heat energy for the evaporation of water in this area, without being transferred to the entire water body to cause its temperature to rise.

[0003] To maximize the efficiency of solar energy utilization, a series of materials with photothermal conversion properties—including carbon-based compounds, metal nanoparticles, polymers, and plasmonic absorbers—have been integrated into solar distillation systems. To reduce the cost of water acquisition, researchers are actively exploring an economical and ecologically balanced method to convert renewable biomass into high-value materials with photothermal properties.

[0004] Given its ubiquity and abundance in nature, biomass, as a renewable energy source, has a low cost of acquisition and a unique porous structure that allows for rapid collection from a wide range of environments. Biomass raw materials are treated with a surface carbonization process and are often used as core components in the manufacture of solar steam generation equipment.

[0005] In other words, in order to improve the effective use of solar energy, a variety of photothermal materials, such as carbon materials, nanoscale metal particles, polymer compounds and plasma absorbing components, have been incorporated into solar evaporation technology. While pursuing the reduction of water resource acquisition expenses, people are working hard to develop a cost-effective and environmentally responsible strategy to transform renewable biomass into value-added materials with photothermal functions. Considering that biomass is a widely existing renewable energy source in nature, it is not only inexpensive, but also has a unique porous structure and is easy to collect from different sources. Therefore, biomass materials currently have very good prospects in the direction of seawater desalination. ZongxingLiu et al. (2024) reported the carbonization of winter melon technology and disclosed Ti3C2T derived from winter melon. X / Carbon aerogel, which exhibits excellent photothermal conversion performance in solar steam generation (Ti3C2Tx / carbon aerogels derived from wintermelon for high-efficiency photothermal conversion, Desalination, Volume 573, 15 March 2024, 117207). A Chinese patent (Announcement No. CN113968994B) discloses a method for preparing photothermal biomass aerogel for solar interfacial evaporation using natural porous cellulose biomass materials (such as eggplant, loofah, sugarcane, radish, yam, bamboo and straw). The obtained photothermal biomass aerogel for solar interfacial evaporation has excellent photothermal performance and can continuously and efficiently convert aqueous solution into water vapor under the irradiation of sunlight. It can be used as a photothermal interface evaporation material for seawater desalination and wastewater purification.

[0006] Although the biomass-integrated solar steam generation system has shown a significant technological leap, it still faces problems in practical application, such as cumbersome production process, low evaporation efficiency, difficulty in obtaining raw materials, seasonal restrictions, and low evaporation rate in high-concentration salt water. These factors constitute obstacles that cannot be ignored. Therefore, it is urgent to develop a new type of solar interface evaporation material, which should include simple preparation process, excellent light-to-heat conversion efficiency and economical production cost. Summary of the invention

[0007] The purpose of the present invention is to provide a salt-tolerant biomass photothermal interface evaporation material and a preparation method and application thereof in view of the above problems.

[0008] In order to achieve its purpose, the present invention adopts the following technical solution:

[0009] The first aspect of the present invention provides a method for preparing a salt-tolerant biomass photothermal interface evaporation material, comprising the following steps:

[0010] S1. Peel the fresh cactus, cut the pulp into chunks, put it into water, and heat it at 50-70° C. under stirring to soften the pulp and remove sugars and impurities (e.g., cytoplasmic impurities on the surface of the pulp);

[0011] S2, taking the block of cactus pulp obtained after the treatment in step S1 out of the water and placing it on a heating plate so that one plane of the block of cactus pulp contacts the high-temperature heating plate until the treated surface turns into a black carbonized layer;

[0012] S3. Take pyrrole and evenly coat it on the carbonized layer of the cactus pulp, then evenly coat an aqueous solution of an oxidant with a concentration of 50 to 80 mM on the carbonized layer coated with pyrrole, and fully polymerize to obtain a salt-tolerant biomass photothermal interface evaporation material - polypyrrole@cactus.

[0013] Preferably, the oxidant is selected from one or more of ammonium persulfate, Fe2(SO4)3, and FeCl3.

[0014] Preferably, the concentration of the oxidant solution is 55-65 mM.

[0015] Preferably, the stirring speed of the stirring bar under the stirring condition in step S1 is 500-700 r / min, the heating time under the stirring condition is 32-40 h, and the water is changed every 3-6 h.

[0016] Preferably, in step S2, the cactus pulp is heated on a flat plate at a temperature of 300-500° C. until the thickness of the carbonized layer reaches 0.8-1.2 mm (more preferably 0.9-1.1 mm); preferably, the flat plate is a metal plate, and the heating time is 3-5 min.

[0017] Preferably, in step S3, 40 to 60 microliters of pyrrole are used for coating per square centimeter of carbonized layer, and then 40 to 60 microliters of oxidant aqueous solution are used for coating per square centimeter of carbonized layer;

[0018] The polymerization reaction time is 0.5 to 2 hours, preferably 0.7 to 1.3 hours.

[0019] Preferably, the block of cactus pulp is in the shape of a cuboid, a cylinder, a prism, a cone or other polyhedron.

[0020] Preferably, the block of cactus pulp is in a rectangular shape, and its length, width and height are set according to the following ratios: length 0.5-1.5 cm, width 0.5-1.5 cm, height 1-3 cm. The block of cactus pulp is not limited to a rectangular shape, as long as it has a surface that can produce a carbonized layer.

[0021] A second aspect of the present invention provides a salt-tolerant biomass photothermal interface evaporation material, which is prepared by any of the preparation methods described above.

[0022] The third aspect of the present invention provides the use of the above-mentioned salt-tolerant biomass photothermal interface evaporation material in solar-driven interface evaporation, photothermal seawater desalination, and sewage treatment.

[0023] The beneficial effects of the present invention are:

[0024] 1. As a plant growing in the desert, cactus pulp has excellent hydrophilicity, but there is no research on using cactus pulp as an interface evaporation material for seawater desalination. The present invention is the first to develop a new type of low-cost salt-tolerant biomass interface evaporation material using cactus as raw material, and its interface evaporation rate is higher than that of most biomass materials.

[0025] 2. The cactus used in the present invention is not restricted by seasons and has low cost. The preparation process only requires simple water bath heating and top surface carbonization treatment to obtain the substrate, without the need for complex and energy-consuming operation steps such as freeze-drying. The process is simple and easy to operate, and large-scale batch production can be achieved.

[0026] 3. At present, the production process of most carbon-based biomass interface evaporation materials such as carbonized wax gourd and carbonized eggplant is relatively complicated, and expensive and energy-consuming equipment such as muffle furnace and freeze dryer are required in the production process. However, the cactus pulp of the present invention only needs to be placed on the pre-heated iron plate, and the surface carbonization scheme is used to replace the overall carbonization scheme of traditional biomass materials. The evaporation rate is also much higher than that of traditional biomass materials such as carbonized wax gourd and carbonized eggplant.

[0027] 4. The polypyrrole@cactus of the present invention has good salt resistance and shows a relatively good water evaporation rate even in a high concentration of 25 wt % salt water.

[0028] 5. The polypyrrole@cactus of the present invention has excellent photothermal performance: it can quickly heat up under sunlight and convert water into water vapor, achieving efficient interfacial evaporation. Under one sunlight, its interfacial evaporation rate can reach 3.6kg / m 2 / h, and it can be seen from Comparative Example 2 that even without photothermal modification of the material, a high water evaporation rate can be obtained by simply carbonizing the surface of the cactus pulp, and the water evaporation rate is as high as 2.9kg / m 2 / h, cactus is an excellent biomass material for interfacial evaporation of seawater desalination.

[0029] 6. Compared with directly carbonizing the cactus pulp to obtain photothermal performance, the present invention uses a simple chemical polymerization method to grow polypyrrole on the top, which not only avoids a large amount of energy consumption, but also retains the hydrophilicity of the cactus pulp itself, with high evaporation efficiency, mild conditions, and strong operability. The present invention uses cactus as a biomass material, which is environmentally friendly, green and non-toxic (edible cactus), so there is no need to worry about its pollution of water bodies when using it as an interface evaporation material. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The upper surface of the photothermal layer of the cactus pulp ( Figure 1 a) and the lower surface of the water transport layer ( Figure 1 b) Water contact angle.

[0031] Figure 2 For Example 2 ( Figure 2 a) and Comparative Example 2 ( Figure 2 b) Changes in infrared thermal imaging within 1 hour under one sun.

[0032] Figure 3 The products obtained in Examples 1-5 and Comparative Examples 1-2 were exposed to sunlight (1000W / m 2 ) Curve of the change of water mass in the beaker over time under irradiation.

[0033] Figure 4 This is the water evaporation rate of the product prepared in Example 2 in real seawater and at different salt concentrations.

[0034] Figure 5 It is the evaporation rate of the product prepared in Example 2 in deionized water, North Sea seawater, and 25 wt% NaCl aqueous solution in 30 cycle experiments. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereto.

[0036] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0037] Embodiment 1:

[0038] 1. Peel the fresh cactus, cut it into pieces (1cm*1cm*1cm), and then put it into ultrapure water for heating and stirring (temperature: 65℃, speed: 600r / min) for 36 hours, changing the water every four hours.

[0039] 2. Place the pulp obtained after heating and stirring in step 1 in a culture dish, wipe off excess moisture on the surface with absorbent paper, and then place it on an iron plate at a temperature of about 400°C and heat for 3-5 minutes until the treated surface part is completely turned into a black carbonized layer with a thickness of about 1 mm.

[0040] 3. Take 50 μl of 99% pure pyrrole (CAS No.: 109-97-7) solution and evenly apply it on the carbonized layer, prepare 60 mM ammonium persulfate solution, and then take 50 μl of the prepared ammonium persulfate solution and evenly apply it on the carbonized layer with pyrrole added. Polymerize for 1 hour to obtain polypyrrole@cactus.

[0041] The natural biomass material cactus is used as the base material and heated and stirred in a magnetic heating stirrer to soften the pulp, remove sugars and cytoplasmic impurities on the pulp surface, and open the water transmission channel of the cactus pulp. The upper surface is then heated to form a carbonized layer, and then polypyrrole is evenly grown on the upper surface of the carbonized layer. The excellent photothermal properties of polypyrrole are combined with the excellent hydrophilicity of cactus pulp to achieve efficient interfacial water evaporation.

[0042] Embodiment 2:

[0043] 1. Peel the fresh cactus, cut it into pieces (1cm*1cm*2cm), and then put it into ultrapure water for heating and stirring (temperature: 65℃, speed: 600r / min) for 36 hours, changing the water every four hours.

[0044] 2. Place the pulp obtained after heating and stirring in step 1 in a culture dish, wipe off excess moisture on the surface with absorbent paper, and then place it on an iron plate at a temperature of about 400°C and heat for 3-5 minutes until the treated surface part is completely turned into a black carbonized layer with a thickness of about 1 mm.

[0045] 3. Take 50 μl of 99% pyrrole solution and evenly apply it on the carbonized layer, prepare 60 mM ammonium persulfate solution, and then take 50 μl of the prepared ammonium persulfate solution and evenly apply it on the carbonized layer with pyrrole added. Polymerize for 1 hour to obtain polypyrrole@cactus.

[0046] Embodiment 3:

[0047] 1. Peel the fresh cactus, cut it into pieces (1cm*1cm*3cm), and then put it into ultrapure water for heating and stirring (temperature: 65℃, speed: 600r / min) for 36 hours, changing the water every four hours.

[0048] 2. Place the pulp obtained after heating and stirring in step 1 in a culture dish, wipe off excess moisture on the surface with absorbent paper, and then place it on an iron plate at a temperature of about 400°C and heat for 3-5 minutes until the treated surface part is completely turned into a black carbonized layer with a thickness of about 1 mm.

[0049] 3. Take 50 μl of 99% pyrrole solution and evenly apply it on the carbonized layer, prepare 60 mM ammonium persulfate solution, and then take 50 μl of the prepared ammonium persulfate solution and evenly apply it on the carbonized layer with pyrrole added. Polymerize for 1 hour to obtain polypyrrole@cactus.

[0050] The difference between Examples 1-3 is that the height of the cactus pulp is different. Different heights (representing the height of the water transport layer) mean different distances of water transmission, which means that the same volume of water needs to overcome different resistances when transported from the bottom of the pulp to the photothermal layer on the top of the pulp, which will result in different amounts of water transported to the photothermal layer on the top of the pulp in the same time, and different amounts of water will affect the evaporation efficiency, which has nothing to do with the ratio of the carbonized layer thickness to the height. The different heights set in Examples 1-3 are to allow different amounts of water to be transported to the top carbonized layer in the same time, and different amounts of water will result in different evaporation rates.

[0051] Embodiment 4:

[0052] 1. Peel the fresh cactus, cut it into pieces (1cm*1cm*2cm), and then put it into ultrapure water for heating and stirring (temperature: 65℃, speed: 600r / min) for 36 hours, changing the water every four hours.

[0053] 2. Place the pulp obtained after heating and stirring in step 1 in a culture dish, wipe off excess moisture on the surface with absorbent paper, and then place it on an iron plate at a temperature of about 400°C and heat for 3-5 minutes until the treated surface part is completely turned into a black carbonized layer with a thickness of about 1 mm.

[0054] 3. Take 50 μl of 99% pyrrole solution and evenly apply it on the carbonized layer, prepare 60 mM ferric chloride solution, and then take 50 μl of the prepared ferric chloride solution and evenly apply it on the carbonized layer with pyrrole added. Polymerize for 1 hour to obtain polypyrrole@cactus.

[0055] Embodiment 5:

[0056] 1. Peel the fresh cactus, cut it into pieces (1cm*1cm*2cm), and then put it into ultrapure water for heating and stirring (temperature: 65℃, speed: 600r / min) for 36 hours, changing the water every four hours.

[0057] 2. Place the pulp obtained after heating and stirring in step 1 in a culture dish, wipe off excess moisture on the surface with absorbent paper, and then place it on an iron plate at a temperature of about 400°C and heat for 3-5 minutes until the treated surface part is completely turned into a black carbonized layer with a thickness of about 1 mm.

[0058] 3. Take 50 μl of 99% pyrrole solution and evenly apply it on the carbonized layer, prepare 60 mM ferric sulfate solution, and then take 50 μl of the prepared ferric sulfate solution and evenly apply it on the carbonized layer with pyrrole added. Polymerize for 1 hour to obtain polypyrrole@cactus.

[0059] Comparative Example 1:

[0060] 1. Peel the fresh cactus and cut it into pieces (1cm*1cm*2cm).

[0061] 2. Place the pulp obtained after heating and stirring in step 1 in a culture dish, wipe off excess moisture on the surface with absorbent paper, and then place it on an iron plate at a temperature of about 400°C and heat for 3-5 minutes until the treated surface part is completely turned into a black carbonized layer with a thickness of about 1 mm. The original cactus interface evaporation material can be obtained.

[0062] Comparative Example 1 is different from Example 2 in that the cactus is not subjected to water bath heating and stirring treatment and pyrrole coating. The results show that its evaporation rate in pure water is only 2.18 kg / m 2 / h.

[0063] Comparative Example 2:

[0064] 1. Peel the fresh cactus, cut it into pieces (1cm*1cm*2cm), and then put it into ultrapure water for heating and stirring (temperature: 65℃, speed: 600r / min) for 36 hours, changing the water every four hours.

[0065] 2. Place the pulp obtained after heating and stirring in step 1 in a culture dish, wipe off excess moisture on the surface with absorbent paper, and then place it on an iron plate at a temperature of about 400°C and heat for 3-5 minutes until the treated surface part is completely turned into a black carbonized layer with a thickness of about 1 mm. This way, the cactus interface evaporation material treated with water bath heating can be obtained.

[0066] Comparative Example 2 is different from Example 2 in that polypyrrole is not grown on the carbonized layer of the cactus pulp, but only a simple surface carbonization treatment is performed. The results show that its evaporation rate in pure water is only 2.90 kg / m 2 / h.

[0067] Example 6 Performance Test

[0068] 1. Contact angle test

[0069] Test method: Figure 1 As shown, a contact angle meter (SDC-100, Dongguan Shengding Precision Instrument Co., Ltd.) was used to measure the upper surface of the photothermal layer of the cactus pulp ( Figure 1 a) and the lower surface of the water transport layer ( Figure 1 b) Water contact angle test was performed.

[0070] The contact angle test was carried out on each part of the product obtained in Example 2, and the results were as follows: Figure 1 As shown, Figure 1 a is the photothermal layer of the product, Figure 1 b is the water transport layer part of the product.

[0071] from Figure 1 As can be seen from the contact angle picture b, the cactus pulp after water bath heating and stirring has good hydrophilicity, and its contact angle is only 21.112°. Figure 1 a It can be seen that the hydrophilicity of the cactus pulp after surface carbonization and photothermal modification is significantly weakened, from 21.112° to 70.957°. Without affecting the water supply, the weakening of the hydrophilicity of the photothermal layer is conducive to strengthening its surface roughness, thereby improving the light absorption capacity, and can also effectively inhibit the accumulation of salt.

[0072] 2. Photothermal heating performance test

[0073] Test method: Example 2 ( Figure 2 a) and Comparative Example 2 ( Figure 2 b) The surface temperature change of the product under one sun illumination condition.

[0074] from Figure 2 It can be seen that the water bodies in which the products prepared in Example 2 and Comparative Example 2 are placed have obvious temperature stratification phenomenon. The upper water body in the beaker, i.e., the photothermal interface, has obvious and concentrated temperature rise, showing good thermal localization behavior. This shows that the same sunlight can be converted into more thermal energy after being absorbed by the photothermal material and the heat is concentrated at the interface to promote water evaporation, thereby reducing heat loss and increasing the evaporation rate. Figure 2 It can be seen that the product prepared in Example 2 is 2 ), its surface temperature rapidly rises to 41°C within 10 minutes, while the surface temperature of the product prepared in Comparative Example 2 further rises to 36°C within 10 minutes. The product prepared in Example 2 obtains a stable surface temperature of 44°C after 30 minutes, while the surface temperature of the product prepared in Comparative Example 2 rises more slowly and finally stabilizes at about 38°C. These results all indicate that the product prepared in Example 2 has excellent light absorption and light-to-heat conversion capabilities.

[0075] 3. Water evaporation test

[0076] Test method: The prepared product was placed in a beaker containing 100 ml of water and irradiated with a xenon lamp (Cel-S500) equipped with an AM 1.5 filter to simulate sunlight. At the same time, a solar meter (SM206-Solar) was used to calibrate the sunlight intensity to maintain at one sun (1000 W / m 2), an electronic balance (AX224ZH / E) records the mass loss of water in the beaker to measure the interfacial evaporation capacity of the sample. Another beaker is filled with 100 ml of water and placed on the balance. The natural evaporation of the system after 1 hour is recorded in a dark field environment as a control group to calculate its actual evaporation efficiency.

[0077] The products obtained in Example 1, Example 2, Example 3, Example 4, Example 5, Comparative Example 1 and Comparative Example 2 were subjected to water evaporation tests. The results of the changes in the mass of water in the beakers of different samples with the solar irradiation time under one sunlight are as follows: Figure 3 As shown in the figure, under the condition of sunlight irradiation, the water mass in the beaker of pure water and different samples changes with the increase of irradiation time. Among them, the water evaporation rate and efficiency of the product prepared in Example 2 can reach 3.6kg / m 2 / h and 91.67%, proving that the polypyrrole@cactus of the present invention has excellent water evaporation effect.

[0078] 4. Salt resistance test

[0079] Test method: In order to study the effect of aqueous solutions with different salt concentrations on the evaporation performance of polypyrrole@cactus, deionized water and sodium chloride were used to prepare sodium chloride aqueous solutions with mass fractions of 5wt%, 10wt%, 15wt%, 20wt%, and 25wt%, respectively, and the product prepared in Example 2 was used for water evaporation experiments. In addition, seawater from Beihai Sea in Guangxi Zhuang Autonomous Region was collected in this study for water evaporation experiments with the product prepared in Example 2, and the average salinity of the seawater was about 3.5wt%.

[0080] In order to study the effect of aqueous solutions with different salt concentrations on the evaporation performance of polypyrrole@cactus, deionized water and sodium chloride were used to prepare sodium chloride aqueous solutions with mass fractions of 5wt%, 10wt%, 15wt%, 20wt%, and 25wt%, respectively, and water evaporation experiments were carried out with the product prepared in Example 2. In addition, seawater from Beihai Sea in Guangxi Zhuang Autonomous Region was collected in this study for water evaporation experiments with the product prepared in Example 2, and the average salinity of the seawater was about 3.5wt%.

[0081] from Figure 4 It can be seen that the water evaporation rate of the product prepared in Example 2 in real seawater is still as high as 3.21 kg / m 2 / h, and in 25wt% salt water, it also showed 1.54kg / m 2 / h water evaporation rate, which reflects the excellent salt resistance of polypyrrole@cactus.

[0082] The evaporation rate is given by the formula It is concluded that (Δm (kg) represents the mass change of the evaporation system, t (h) represents the evaporation time, S (m 2) is the effective evaporation area of ​​the evaporator).

[0083] 5. Durability test

[0084] Test method: From the previous experiments, we can get the photothermal performance, water transmission performance and salt resistance of the polypyrrole @ cactus of the present invention. In order to further understand the durability of polypyrrole @ cactus, the product in Example 2 was subjected to 30 cycles of solar interface evaporation experiments (each time the illumination experiment was performed for 1 hour, and then placed in a dark environment for a period of time, and the next experiment was performed after the evaporation surface temperature of the material returned to room temperature).

[0085] From the previous experiments, we can get the light and heat performance, water transmission performance and salt resistance of the polypyrrole @ cactus of the present invention. In order to further understand the durability of polypyrrole @ cactus, the product in Example 2 was subjected to 30 cycles of solar interface evaporation experiments in deionized water, North Sea seawater, and 25wt% NaCl solution (each time the illumination experiment was performed for 1 hour, and then placed in a dark environment for a period of time, and the next experiment was performed after the evaporation surface temperature of the material returned to room temperature). The evaporation rate obtained from the experiment is as follows Figure 5 As shown in the figure, it can be seen that in the solar interfacial evaporation experiment of 30 consecutive cycles, the evaporation rate of the material prepared by the present invention in pure water and North Sea seawater does not change much, and the average evaporation rate is 3.53 kg / m 2 / h and 3.14kg / m 2 / h, and almost no salt crystallization occurred on the surface of the material in each experiment. However, as the salt concentration of the NaCl aqueous solution increased, salt precipitation occurred and the evaporation rate decreased. The average evaporation rate of the 25wt% NaCl aqueous solution in 30 cycles of solar interfacial evaporation experiments was only 1.46kg / m 2 / h, and with the increase of the number of cycle experiments, the evaporation rate decreased significantly, which shows that high concentration of salt water has a certain effect on the evaporation rate of the material, but Figure 5 It can be seen that regardless of the salt concentration, the evaporation rate of this material changes little in the 30-cycle evaporation experiment, which reflects the good durability of polypyrrole@cactus.

Claims

1. A method for preparing a salt-tolerant biomass photothermal interface evaporation material, characterized in that: The steps include: S1. Peel the fresh cactus, cut the pulp into pieces and put it into water, and heat it at 50-70° C. under stirring to soften the pulp and remove sugars and impurities; S2, taking the block of cactus pulp obtained after the treatment in step S1 out of the water and placing it on a heating plate so that one plane of the block of cactus pulp contacts the high-temperature heating plate until the treated surface turns into a black carbonized layer; S3. Take pyrrole and evenly coat it on the carbonized layer of the cactus pulp, then evenly coat an aqueous solution of an oxidant with a concentration of 50 to 80 mM on the carbonized layer coated with pyrrole, and fully polymerize to obtain a salt-tolerant biomass photothermal interface evaporation material - polypyrrole@cactus.

2. The preparation method according to claim 1, characterized in that: The oxidant is selected from one or more of ammonium persulfate, Fe2(SO4)3, and FeCl3.

3. The preparation method according to claim 1, characterized in that: The concentration of the oxidant solution is 55-65 mM.

4. The preparation method according to claim 1, characterized in that: The stirring speed of the stirring bar under the stirring condition in step S1 is 500-700 r / min, and the heating time under the stirring condition is 32-40 hours; the water is changed every 3-6 hours.

5. The preparation method according to claim 1, characterized in that: In step S2, the cactus pulp is heated on a flat plate at a temperature of 300-500° C. until the thickness of the carbonized layer reaches 0.8-1.2 mm; preferably, the flat plate is a metal plate, and the heating time is 3-5 min.

6. The preparation method according to claim 1, characterized in that: In step S3, Coating with 40 to 60 microliters of pyrrole per square centimeter of carbonized layer, and then coating with 40 to 60 microliters of oxidant aqueous solution per square centimeter of carbonized layer; The polymerization reaction time is 0.5 to 2 hours, preferably 0.7 to 1.3 hours.

7. The preparation method according to claim 1, characterized in that: The block-shaped cactus pulp is in the shape of a cuboid, a cylinder, a prism, a cone or other polyhedrons.

8. The preparation method according to claim 7, characterized in that: The block of cactus pulp is in the shape of a cuboid, and its length, width and height are arranged according to the following proportions: length 0.5-1.5 cm, width 0.5-1.5 cm, height 1-3 cm.

9. A salt-tolerant biomass photothermal interface evaporation material, characterized in that: The preparation method is described in any one of claims 1 to 8.

10. Use of the salt-tolerant biomass photothermal interface evaporation material according to claim 9 in solar-driven interface evaporation, photothermal seawater desalination, and sewage treatment.

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