Carbon quantum dot / perylene bisimide / wood-based composite aerogel solar evaporator and preparation method and application thereof

Abstract

The invention relates to a carbon quantum dot / perylene bisimide / wood-based composite aerogel solar evaporator and a preparation method and application thereof.The method includes the steps that carbon quantum dots are prepared through a hydrothermal method, delignification and hemicelluloses removal are conducted on balsa wood to prepare wood-based aerogel, then the carbon quantum dots and perylene bisimide are self-assembled on the wood-based aerogel, and the carbon quantum dot / perylene bisimide / wood-based composite aerogel solar evaporator is obtained. The carbon quantum dot / perylene bisimide / wood-based composite aerogel solar evaporator is obtained. The composite aerogel constructed by the invention has an ordered porous structure, and a stable rapid water supply channel can be formed; the carbon quantum dot / perylene bisimide self-assembly structure has a wide absorption spectrum and can effectively collect solar energy and convert the solar energy into heat. Compared with the prior art, the invention has the advantages of low cost, stable structure, good evaporation performance, strong salt resistance, wide application prospect in the fields of seawater desalination and sewage purification, and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of solar interface evaporation, and in particular relates to a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator and a preparation method and application thereof. Background Art

[0002] With the rapid growth of population and the booming industrial society, the shortage of fresh water resources has become a global problem. Seawater accounts for about 97% of the total water on the earth. How to obtain fresh water from the abundant seawater reserves has attracted widespread attention. Traditional seawater desalination technologies include multi-stage flash evaporation, multi-effect evaporation, electrodialysis and reverse osmosis, which require complex equipment and facilities and a large amount of fossil energy consumption. Using inexhaustible green energy solar energy to replace non-renewable fossil fuels to achieve seawater desalination can not only effectively reduce costs, but also minimize the negative impact on the environment. Solar interfacial evaporation technology absorbs solar energy and converts it into thermal energy to drive seawater evaporation. Because the photothermal conversion and interfacial evaporation are limited to the liquid-gas interface, the heat dissipation to the surrounding environment and water bodies can be minimized, thereby improving the evaporation efficiency. Therefore, solar interfacial evaporation is considered to be a sustainable and environmentally friendly method of using solar energy to efficiently produce clean fresh water.

[0003] The solar interfacial evaporation system consists of photothermal conversion materials and floating evaporation structures. At present, metal materials, carbon-based materials, and plasma materials are often used as photothermal conversion materials due to their high photothermal conversion efficiency. However, due to their high cost and complex preparation process, it is difficult to achieve large-scale application. Perylene imide-based organic supramolecular materials have the characteristics of molecular structure adjustability, excellent light absorption properties, superior photocatalytic oxidation properties and low cost, and show great application potential in electronic devices, catalysis, energy storage, biomedicine and environmental fields. However, the application of perylene imide-based organic supramolecular materials in the field of solar interfacial evaporation is restricted by their limited absorption in the visible light range.

[0004] Patent CN116553667A discloses a highly efficient salt-rejecting solar evaporator for high-salt water treatment. Compared with this patent, carbon nanofibers and graphene oxide are both carbon-based materials. Due to their high photothermal conversion efficiency, they are often used as photothermal conversion materials. However, due to their high cost and complex preparation process, they are difficult to achieve large-scale application. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator and its preparation method and application.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] On the one hand, the present invention provides a method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator, characterized in that it comprises the following steps:

[0008] (1) soaking balsa wood in a sodium chlorite aqueous solution and a sodium hydroxide aqueous solution in sequence to remove lignin and hemicellulose, repeatedly washing with an ethanol aqueous solution, and freeze-drying to obtain a wood-based aerogel;

[0009] (2) dissolving citric acid and ethylenediamine in deionized water and transferring to a polytetrafluoroethylene-lined autoclave for reaction to obtain a brown-black solution, which was dialyzed and dried to obtain carbon quantum dots;

[0010] (3) 3,4,9,10-tetracarboxylic dianhydride, β-alanine and imidazole are mixed, heated to react under an inert gas atmosphere, and stirred for the first time to obtain a mixture, and the obtained mixture is dissolved in a mixed solution of ethanol and hydrochloric acid, stirred overnight, filtered, washed, and dried to obtain perylene imide.

[0011] (4) dispersing the perylene imide obtained in step (3) in deionized water, stirring, ultrasonicating, sequentially adding triethylamine, the carbon quantum dots obtained in step (2), and the wood-based aerogel obtained in step (1), adding nitric acid while stirring, filtering, washing, and freeze-drying to obtain a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator.

[0012] Furthermore, in step (1), the sodium chlorite aqueous solution is adjusted to a pH of 4.5-4.7 with acetic acid, the concentration of the sodium chlorite aqueous solution is 1-3wt%, the system temperature is 80-120°C, the soaking time is 8-12h, the concentration of the sodium hydroxide aqueous solution is 5-9wt%, the system temperature is 70-90°C, the soaking time is 3-8h, and the solution is washed with an ethanol-water solution. The freezing temperature in the freeze-drying is -60°C, the freezing time is 20-30h, and the drying part in the freeze-drying is carried out under a vacuum atmosphere for a drying time of 20-36h.

[0013] Furthermore, in step (2), the weight ratio of citric acid, ethylenediamine and deionized water is 1-3:0.3-0.4:10-20, the reaction temperature is 150-200°C, and the reaction time is 5-8h.

[0014] Furthermore, in step (3), the mass ratio of 3,4,9,10-tetracarboxylic dianhydride, β-alanine and imidazole is 1-3:1-3:10-20, the inert gas is nitrogen, the heating temperature is 100-120°C, the first stirring time is 3-5h, and preferably, the stirring time is 4h.

[0015] Furthermore, the mixture in step (3) is dissolved in the mixed solution and stirred overnight, and the concentration is 2.4%-13.0% w / v, the volume ratio of ethanol and hydrochloric acid in the mixed solution is 1-2:1-3, the ethanol is anhydrous ethanol, and the concentration of the hydrochloric acid is 1-3 mol / L.

[0016] Furthermore, the filtration in step (3) uses a 0.4-0.5 μm membrane of hydrophilic PTFE material, preferably a 0.45 μm membrane, the washing uses deionized water, and the drying is carried out in a vacuum environment at a drying temperature of 50-70°C, preferably 60°C, and the drying time is 40-50h.

[0017] Furthermore, in step (4), the mass ratio of perylene imide, wood-based aerogel, deionized water, and carbon quantum dots is 0.01-0.2: 0.1-0.2: 50-100: 0.01-0.2, the volume ratio of deionized water, triethylamine, and nitric acid is 50-100: 0.2-0.3: 1-5, and the concentration of nitric acid is 3-5 mol / L.

[0018] On the other hand, the present invention also provides a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator, which is prepared by any of the preparation methods described above.

[0019] In a third aspect, the present invention also provides an application of a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator in seawater desalination and sewage purification.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The present invention uses wood-based aerogel as a matrix material, and obtains a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator having a self-supporting three-dimensional porous material by self-assembling carbon quantum dots and perylene imide thereon. The carbon quantum dot / perylene imide composite structure enhances the light absorption performance in the visible light range and improves the light-to-heat conversion efficiency.

[0022] (2) The composite aerogel used in the present invention has a hydrophilic ordered porous structure, which provides a fast and stable water transmission channel for the evaporator, and the multiple reflections of sunlight in the porous structure further enhance the light absorption performance.

[0023] (3) The preparation method of the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator provided by the present invention is simple, low-cost, and environmentally friendly, and has great value and significance for practical applications.

[0024] (4) The carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator provided by the present invention can be used not only for seawater desalination, but also for sewage purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a comparison chart of various ion concentrations before and after the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in Example 2 of the present invention treats actual seawater.

[0026] Figure 2 This is the ultraviolet absorption spectrum of the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in Example 2 of the present invention before and after purification of methylene blue dye.

[0027] Figure 3 The ultraviolet absorption spectra of the pure wood-based aerogel solar evaporator prepared in Comparative Example 1 of the present invention before and after purification of methylene blue dye.

[0028] Figure 4 This is the ultraviolet absorption spectrum of the perylene imide / wood-based composite aerogel solar evaporator prepared in Comparative Example 2 of the present invention before and after purification of methylene blue dye.

[0029] Figure 5 This is the ultraviolet absorption spectrum of the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in Example 2 of the present invention before and after purification of Rhodamine B dye.

[0030] Figure 6 This is the ultraviolet absorption spectrum of the pure wood-based aerogel solar evaporator prepared in Comparative Example 1 of the present invention before and after purification of Rhodamine B dye.

[0031] Figure 7 This is the ultraviolet absorption spectrum of the perylene imide / wood-based composite aerogel solar evaporator prepared in Comparative Example 2 of the present invention before and after purification of Rhodamine B dye. DETAILED DESCRIPTION

[0032] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0033] In the following examples, raw materials or processing techniques, unless otherwise specified, are conventional commercially available raw materials or conventional processing techniques in the art.

[0034] Example 1

[0035] A method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator comprises the following steps:

[0036] (1) Preparation of wood-based aerogel: At 80°C, the pH of the sodium chlorite aqueous solution was adjusted to 4.6 with acetic acid, and then the balsa wood was first soaked in a 3wt% sodium chlorite aqueous solution for 12 hours until the yellow lignin was completely removed and the wood sample turned white. The treated sample was then carefully rinsed with an ethanol-water solution to remove any residual chemicals. The obtained wood sample was then soaked in a 9wt% sodium hydroxide solution at 70°C for 8 hours to remove the hemicellulose part. The treated sample was then carefully rinsed with an ethanol-water solution to remove any residual chemicals. Finally, the sample was frozen in a -60°C cold trap for 20 hours and vacuum dried in a freeze dryer for 24 hours to prepare the wood-based aerogel.

[0037] (2) Preparation of carbon quantum dots: citric acid (1 g) and ethylenediamine (300 μL) were dissolved in deionized water (10 mL), and the mixture was transferred to a polytetrafluoroethylene-lined autoclave and reacted at 150°C for 8 h. After the reaction, the mixture was cooled to obtain a brown-black solution. The solution was dialyzed with a 1000 Da dialysis bag for 48 h. The dialyzed carbon dots were dried at 60°C to obtain a solid to obtain carbon quantum dots.

[0038] (3) Preparation of perylene imide: 3,4,9,10-tetracarboxylic dianhydride (1 g), β-alanine (1 g) and imidazole (10 g) were mixed in a three-necked flask, and stirred at 110°C for 4 h under nitrogen protection; the mixture was dissolved in 100 mL of anhydrous ethanol and 100 mL of hydrochloric acid (1 mol / L) and stirred overnight, and the mixed solution was filtered with a 0.45 μm membrane and washed with pure water until the pH became neutral, and the obtained solid was dried in a vacuum oven at 60°C to obtain perylene imide.

[0039] (4) Preparation of carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator: 0.01 g of the prepared perylene imide was dispersed in 50 mL of deionized water. After continuous stirring and ultrasonic treatment, 0.2 mL of triethylamine was added, followed by 0.01 g of the prepared carbon quantum dots and 0.2 g of the prepared wood-based aerogel. 1 mL of 3 mol / L nitric acid was added under stirring, and then filtered and washed. The sample was frozen in a -60°C cold trap for 20 h and vacuum dried in a freeze dryer for 24 h to prepare a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator.

[0040] Example 2

[0041] A method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator comprises the following steps:

[0042] (1) Preparation of wood-based aerogel: Preparation of wood-based aerogel: At 90°C, the pH of the sodium chlorite aqueous solution was adjusted to 4.6 with acetic acid, and then the balsa wood was first soaked in a 2wt% sodium chlorite aqueous solution for 11 hours until the yellow lignin was completely removed and the wood sample turned white. The treated sample was then carefully rinsed with an ethanol-water solution to remove any residual chemicals. The obtained wood sample was then soaked in an 8wt% sodium hydroxide solution at an ambient temperature of 75°C for 7 hours to remove the hemicellulose part. The treated sample was then carefully rinsed with an ethanol-water solution to remove any residual chemicals. Finally, the sample was frozen in a -60°C cold trap for 24 hours and vacuum dried in a freeze dryer for 28 hours to prepare the wood-based aerogel.

[0043] (2) Preparation of carbon quantum dots: Citric acid (1.5 g) and ethylenediamine (350 μL) were dissolved in deionized water (15 mL), and the mixture was transferred to a polytetrafluoroethylene-lined autoclave and reacted at 160°C for 7 h. After the reaction, the mixture was cooled to obtain a brown-black solution. The solution was dialyzed with a 1000 Da dialysis bag for 48 h. The dialyzed carbon dots were dried at 60°C to form a solid to obtain carbon quantum dots.

[0044] (3) Preparation of perylene imide: 3,4,9,10-tetracarboxylic dianhydride (1.5 g), β-alanine (1.5 g) and imidazole (15 g) were mixed in a three-necked flask, and stirred at 110°C for 4 h under nitrogen protection; the mixture was dissolved in 150 mL of anhydrous ethanol and 150 mL of hydrochloric acid (1.5 mol / L) and stirred overnight, and the mixed solution was filtered with a 0.45 μm membrane and washed with pure water until the pH became neutral. The obtained solid was dried in a vacuum oven at 60°C to obtain perylene imide.

[0045] (4) Preparation of carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator: 0.1 g of the prepared perylene imide was dispersed in 60 mL of deionized water. After continuous stirring and ultrasonic treatment, 0.23 mL of triethylamine was added, followed by 0.1 g of the prepared carbon quantum dots and 0.17 g of the prepared wood-based aerogel. Under stirring, 2 mL of 3.5 mol / L nitric acid was added. The sample was then filtered and washed and frozen in a -60°C cold trap for 24 h. It was then vacuum dried in a freeze dryer for 28 h to prepare a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator.

[0046] Example 3

[0047] A method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator comprises the following steps:

[0048] (1) Preparation of wood-based aerogel: Preparation of wood-based aerogel: At 100°C, the pH of the sodium chlorite aqueous solution was adjusted to 4.6 with acetic acid, and then the balsa wood was first soaked in a 1.5wt% sodium chlorite aqueous solution for 10 hours until the yellow lignin was completely removed and the wood sample turned white. The treated sample was then carefully rinsed with an ethanol-water solution to remove any residual chemicals; the obtained wood sample was then soaked in a 6wt% sodium hydroxide solution at an ambient temperature of 80°C for 5 hours to remove the hemicellulose part; the treated sample was then carefully rinsed with an ethanol-water solution to remove any residual chemicals; finally, the sample was frozen in a -60°C cold trap for 28 hours and vacuum dried in a freeze dryer for 32 hours to prepare the wood-based aerogel.

[0049] (2) Preparation of carbon quantum dots: Citric acid (2 g) and ethylenediamine (370 μL) were dissolved in deionized water (17 mL), and the mixture was transferred to a polytetrafluoroethylene-lined autoclave and reacted at 180°C for 6 h. After the reaction, the mixture was cooled to obtain a brown-black solution. The solution was dialyzed with a 1000 Da dialysis bag for 48 h. The dialyzed carbon dots were dried at 60°C to obtain a solid to obtain carbon quantum dots.

[0050] (3) Preparation of perylene imide: 3,4,9,10-tetracarboxylic dianhydride (2 g), β-alanine (2 g) and imidazole (17 g) were mixed in a three-necked flask, and stirred at 110°C for 4 h under nitrogen protection; the mixture was dissolved in 170 mL of ethanol and 200 mL of hydrochloric acid (2 mol / L) and stirred overnight, and the mixed solution was filtered with a 0.45 μm membrane and washed with pure water until the pH became neutral. The obtained solid was dried in a vacuum oven at 60°C to obtain perylene imide.

[0051] (4) Preparation of carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator: 0.15 g of the prepared perylene imide was dispersed in 80 mL of deionized water. After continuous stirring and ultrasonic treatment, 0.25 mL of triethylamine was added, followed by 0.15 g of the prepared carbon quantum dots and 0.15 g of the prepared wood-based aerogel. Under stirring, 3 mL of 4 mol / L nitric acid was added. The mixture was then filtered and washed, and the sample was frozen in a -60°C cold trap for 28 h. It was then vacuum dried in a freeze dryer for 32 h to prepare a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator.

[0052] Example 4

[0053] A method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator comprises the following steps:

[0054] (1) Preparation of wood-based aerogel: Preparation of wood-based aerogel: At 120°C, the pH of the sodium chlorite aqueous solution was adjusted to 4.6 with acetic acid, and then the balsa wood was first soaked in a 1wt% sodium chlorite aqueous solution for 8 hours until the yellow lignin was completely removed and the wood sample turned white. The treated sample was then carefully rinsed with an ethanol-water solution to remove any residual chemicals; the wood sample was then soaked in a 5wt% sodium hydroxide solution at 90°C for 3 hours to remove the hemicellulose part; the treated sample was then carefully rinsed with an ethanol-water solution to remove any residual chemicals; finally, the sample was frozen in a -60°C cold trap for 30 hours and vacuum dried in a freeze dryer for 36 hours to prepare the wood-based aerogel.

[0055] (2) Preparation of carbon quantum dots: citric acid (3 g) and ethylenediamine (400 μL) were dissolved in deionized water (20 mL), and the mixture was transferred to a polytetrafluoroethylene-lined autoclave and reacted at 200 °C for 5 h. After the reaction, the mixture was cooled to obtain a brown-black solution. The solution was dialyzed with a 1000 Da dialysis bag for 48 h. The dialyzed carbon dots were dried at 60 °C to obtain a solid to obtain carbon quantum dots.

[0056] (3) Preparation of perylene imide: 3,4,9,10-tetracarboxylic dianhydride (3 g), β-alanine (3 g) and imidazole (20 g) were mixed in a three-necked flask and stirred at 110°C for 4 h under nitrogen protection; the mixture was dissolved in 200 mL of ethanol and 300 mL of hydrochloric acid (3 mol / L) and stirred overnight, and the mixed solution was filtered with a 0.45 μm membrane and washed with pure water until the pH became neutral. The resulting red solid was dried in a vacuum oven at 60°C to obtain perylene imide.

[0057] (4) Preparation of carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator: 0.2 g of the prepared perylene imide was dispersed in 100 mL of deionized water. After continuous stirring and ultrasonic treatment, 0.3 mL of triethylamine was added, followed by 0.2 g of the prepared carbon quantum dots and 0.1 g of the prepared wood-based aerogel. 5 mL of 5 mol / L nitric acid was added under stirring, and then filtered and washed. The sample was frozen in a -60°C cold trap for 30 h and vacuum dried in a freeze dryer for 36 h to prepare a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator.

[0058] Comparative Example 1

[0059] A method for preparing a pure wood-based aerogel solar evaporator comprises the following steps: adjusting the pH of a sodium chlorite aqueous solution to 4.6 with acetic acid at 100°C, then soaking balsa wood in a sodium chlorite aqueous solution with a mass fraction of 2wt% for 12=0h, until the yellow lignin is completely removed and the wood sample turns white, and then carefully rinsing the treated sample with an ethanol-water solution to remove any residual chemical substances; soaking the obtained wood sample in an 8wt% sodium hydroxide solution at an ambient temperature of 80°C for 3h to remove the hemicellulose part; then carefully rinsing the treated sample with an ethanol-water solution to remove any residual chemical substances; finally freezing the sample in a -60°C cold trap for 24h, and vacuum drying it in a freeze dryer for 36h to prepare the wood-based aerogel.

[0060] Comparative Example 2

[0061] A method for preparing a perylene imide / wood-based composite aerogel solar evaporator comprises the following steps:

[0062] (1) Preparation of wood-based aerogel: At 100°C, the pH of the sodium chlorite aqueous solution was adjusted to 4.6 with acetic acid, and then the balsa wood was first soaked in a 2wt% sodium chlorite aqueous solution for 10 hours until the yellow lignin was completely removed and the wood sample turned white. The treated sample was then carefully rinsed with an ethanol-water solution to remove any residual chemicals. The obtained wood sample was then soaked in an 8wt% sodium hydroxide solution at 80°C for 3 hours to remove the hemicellulose part. The treated sample was then carefully rinsed with an ethanol-water solution to remove any residual chemicals. Finally, the sample was frozen in a -60°C cold trap for 24 hours and vacuum dried in a freeze dryer for 36 hours to prepare the wood-based aerogel.

[0063] (2) Preparation of perylene imide: 3,4,9,10-tetracarboxylic dianhydride (2 g), β-alanine (2 g) and imidazole (15 g) were mixed in a three-necked flask, and stirred at 110°C for 4 h under nitrogen protection; the mixture was dissolved in 150 mL of ethanol and 200 mL of hydrochloric acid (2 mol / L) and stirred overnight, and the mixed solution was filtered with a 0.45 μm membrane and washed with pure water until the pH became neutral. The resulting red solid was dried in a vacuum oven at 60°C to obtain perylene imide.

[0064] (3) Preparation of perylene imide / wood-based composite aerogel solar evaporator: 0.1 g of perylene imide was dispersed in 75 mL of deionized water. After continuous stirring and ultrasonic treatment, 0.25 mL of triethylamine was added, followed by 0.15 g of the prepared wood-based aerogel. 3 mL of 4 mol / L nitric acid was added under stirring. The mixture was then filtered and washed. The sample was then frozen in a -60°C cold trap for 24 h and vacuum dried in a freeze dryer for 36 h to obtain a perylene imide / wood-based composite aerogel solar evaporator.

[0065] Application: Sodium chloride is dissolved in deionized water to prepare simulated seawater with a mass fraction of sodium chloride of 3.5 wt%. The carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared by the present invention is placed in simulated seawater for a continuous evaporation experiment for 7 hours. The average evaporation rate of the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in Example 1 is 1.85 kg / m 2 / h, the average evaporation rate of the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in Example 2 is 2.39 kg / m 2 / h, the average evaporation rate of the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in Example 3 is 2.76 kg / m 2 / h, the average evaporation rate of the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in Example 4 is 2.69 kg / m 2 / h, the average evaporation rate of the pure wood-based aerogel solar evaporator prepared in Comparative Example 1 is 1.05kg / m 2 / h, the average evaporation rate of the perylene imide / wood-based composite aerogel solar evaporator prepared in Comparative Example 2 is 2.04 kg / m 2 / h.

[0066] In order to verify the performance of the carbon quantum dots / perylene imide / wood-based composite aerogel solar evaporator prepared above for seawater desalination and sewage purification, the carbon quantum dots / perylene imide / wood-based composite aerogel solar evaporator prepared above is used to desalinate seawater and purify methylene blue dye solution (concentration of 1000ppm) and rhodamine B dye solution (concentration of 1000ppm) respectively;

[0067] Desalination of seawater: The carbon quantum dots / perylene imide / wood-based composite aerogel solar evaporator prepared in Example 2 was used to desalinate seawater. The Na+ in the East China Sea seawater and desalinated water was tested using an inductively coupled plasma spectrometer (ICP-OES, Agilent 5110). + , K + , Ga 2+ Mg 2+The concentration of metal ions in seawater before and after treatment is as follows: Figure 1 As shown in the figure, it can be seen that the concentrations of the four metal ions in seawater are greatly reduced, far below the WHO standard, which shows that the carbon quantum dots / perylene imide / wood-based composite aerogel solar evaporator prepared above has an excellent desalination effect on seawater;

[0068] Purification of methylene blue dye solution:

[0069] The carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in Example 2 was used to purify the methylene blue dye solution, and the ultraviolet absorption spectra of the methylene blue dye solution before and after purification were obtained by using an ultraviolet visible spectrophotometer (UV-5500). Figure 2 As shown in the figure, it can be seen that the absorbance of the purified methylene blue dye solution in the wavelength range of 300 to 800 nm is almost zero, which shows that the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in the above Example 2 has excellent purification performance for wastewater containing methylene blue.

[0070] The pure wood-based aerogel solar evaporator prepared in the above comparative example 1 was used to purify the methylene blue dye solution, and the ultraviolet absorption spectra of the methylene blue dye solution before and after purification were obtained by testing with an ultraviolet visible spectrophotometer (UV-5500). Figure 3 As shown in the figure, it can be seen that the absorbance of the purified methylene blue dye solution in the wavelength range of 300 to 800 nm almost coincides with the spectrum of the original dye solution. It can be seen that the pure wood-based aerogel solar evaporator prepared in the above comparative example 1 has almost no purification performance for wastewater containing methylene blue.

[0071] The perylene imide / wood-based composite aerogel solar evaporator prepared in the above comparative example 2 was used to purify the methylene blue dye solution, and the ultraviolet absorption spectra of the methylene blue dye solution before and after purification were obtained by testing with an ultraviolet visible spectrophotometer (UV-5500). Figure 4 As shown in the figure, it can be seen that the absorbance of the purified methylene blue dye solution in the wavelength range of 300 to 800 nm is reduced. It can be seen that the perylene imide / wood-based composite aerogel solar evaporator prepared in the above comparative example 2 has purification performance for wastewater containing methylene blue, but the effect is general.

[0072] Purification of Rhodamine B stain:

[0073] The carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in Example 2 was used to purify the Rhodamine B dye solution, and the ultraviolet absorption spectra of the Rhodamine B dye solution before and after purification were obtained by testing with an ultraviolet visible spectrophotometer (UV-5500). Figure 3As shown in the figure, it can be seen that the absorbance of the purified Rhodamine B dye solution in the wavelength range of 300 to 800 nm is almost zero, which shows that the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator prepared in the above Example 2 has excellent purification performance for wastewater containing Rhodamine B.

[0074] The pure wood-based aerogel solar evaporator prepared in the above comparative example 1 was used to purify the Rhodamine B dye solution, and the ultraviolet absorption spectra of the Rhodamine B dye solution before and after purification were obtained by testing with an ultraviolet visible spectrophotometer (UV-5500). Figure 6 As shown in the figure, it can be seen that the absorbance of the purified Rhodamine B dye solution in the wavelength range of 300 to 800 nm almost coincides with the spectrum of the original dye solution. It can be seen that the pure wood-based aerogel solar evaporator prepared in the above comparative example 1 has almost no purification performance for wastewater containing Rhodamine B.

[0075] The perylene imide / wood-based composite aerogel solar evaporator prepared in the above comparative example 2 was used to purify the Rhodamine B dye solution, and the ultraviolet absorption spectra of the Rhodamine B dye solution before and after purification were obtained by testing with an ultraviolet visible spectrophotometer (UV-5500). Figure 7 As shown in the figure, it can be seen that the absorbance of the purified Rhodamine B dye solution in the wavelength range of 300 to 800 nm is reduced. It can be seen that the perylene imide / wood-based composite aerogel solar evaporator prepared in the above comparative example 2 has purification performance for wastewater containing Rhodamine B, but the effect is general.

[0076] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator, characterized in that: The steps include: (1) soaking balsa wood in a sodium chlorite aqueous solution and a sodium hydroxide aqueous solution in sequence to remove lignin and hemicellulose, repeatedly washing with an ethanol aqueous solution, and freeze-drying to obtain a wood-based aerogel; (2) dissolving citric acid and ethylenediamine in deionized water and transferring to a polytetrafluoroethylene-lined autoclave for reaction to obtain a brown-black solution, which was dialyzed and dried to obtain carbon quantum dots; (3) mixing 3,4,9,10-tetracarboxylic dianhydride, β-alanine, and imidazole, heating the mixture under an inert gas atmosphere for reaction, and performing a first stirring to obtain a mixture, dissolving the mixture in a mixed solution of ethanol and hydrochloric acid, stirring overnight, filtering, washing, and drying to obtain perylene imide; (4) dispersing the perylene imide obtained in step (3) in deionized water, stirring, ultrasonicating, sequentially adding triethylamine, the carbon quantum dots obtained in step (2), and the wood-based aerogel obtained in step (1), adding nitric acid while stirring, filtering, washing, and freeze-drying to obtain a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator.

2. The method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator according to claim 1, characterized in that: The sodium chlorite aqueous solution in step (1) is adjusted to a pH of 4.5-4.7 with acetic acid, the concentration of the sodium chlorite aqueous solution is 1-3wt%, the system temperature is 80-120°C, and the soaking time is 8-12h. The concentration of the sodium hydroxide aqueous solution is 5-9wt%, the system temperature is 70-90°C, and the soaking time is 3-8h. The solution is washed with an ethanol-water solution. The freezing temperature in the freeze-drying is -60°C, the freezing time is 20-30h, and the drying part in the freeze-drying is carried out under a vacuum atmosphere for a drying time of 20-36h.

3. The method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator according to claim 1, characterized in that: In step (2), the weight ratio of citric acid, ethylenediamine and deionized water is 1-3:0.3-0.4:10-20, the reaction temperature is 150-200° C., and the reaction time is 5-8 hours.

4. The method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator according to claim 1, characterized in that: In step (3), the mass ratio of 3,4,9,10-tetracarboxylic dianhydride, β-alanine and imidazole is 1-3:1-3:10-20, the inert gas is nitrogen, the heating temperature is 100-120° C., and the first stirring time is 3-5 h.

5. The method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator according to claim 1, characterized in that: The mixture in step (3) is dissolved in the mixed solution and stirred overnight, with a concentration of 2.4%-13.0% w / v, the volume ratio of ethanol to hydrochloric acid in the mixed solution is 1-2:1-3, the ethanol is anhydrous ethanol, and the concentration of the hydrochloric acid is 1-3 mol / L.

6. The method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator according to claim 1, characterized in that: The filtration in step (3) uses a 0.4-0.5 μm membrane of hydrophilic PTFE material, the washing uses deionized water, and the drying is carried out in a vacuum environment at a drying temperature of 50-70° C. and a drying time of 40-50 h.

7. The method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator according to claim 1, characterized in that: In step (4), the mass ratio of perylene imide, wood-based aerogel, deionized water and carbon quantum dots is 0.01-0.2: 0.1-0.2: 50-100: 0.01-0.2, the volume ratio of deionized water, triethylamine and nitric acid is 50-100: 0.2-0.3: 1-5, and the concentration of nitric acid is 3-5 mol / L.

8. The method for preparing a carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator according to claim 1, characterized in that: In step (4), deionized water is used for washing. The freezing temperature in the freeze-drying is -60°C and the freezing time is 20-30 hours. The drying part in the freeze-drying is carried out in a vacuum atmosphere and the drying time is 20-36 hours.

9. A carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator, prepared by the preparation method according to any one of claims 1 to 8.

10. Application of the carbon quantum dot / perylene imide / wood-based composite aerogel solar evaporator as claimed in claim 9 in seawater desalination.

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