A method for preparing porous nitrogen-containing carbon materials

Abstract

This application discloses a method for preparing porous nitrogen-based carbon materials. The raw materials used are ethanolamine, carbon tetrachloride, tert-butanol, and terpineol. These four substances are mixed with mesoporous molecular sieves, heated in an oil bath, and dried to obtain a preliminary crude nitrogen-based carbon product. Then, carbonization is carried out in a tube furnace at 400-900℃ to completely carbonize the unreacted ethanolamine, carbon tetrachloride, tert-butanol, and terpineol in the crude nitrogen-based carbon product. After repeated washing with hydrofluoric acid and vacuum drying, the porous nitrogen-based carbon material is obtained. The selection of raw materials and the control of carbonization temperature result in a porous nitrogen-based carbon material with a large number of porous structures, a large specific surface area, increased vapor escape channels, and decreased light reflectivity, exhibiting good light absorption performance, an expanded absorption spectrum range, and enhanced absorption capacity. Therefore, using this porous nitrogen-based carbon material for desalination improves both the evaporation rate and the light conversion rate.

Description

Technical Field

[0001] This application relates to the field of solar-driven interfacial water evaporation technology, and in particular to a method for preparing porous nitrogen-containing carbon materials. Background Technology

[0002] Industrial wastewater desalination processes generate large amounts of concentrated brine containing toxic substances such as inorganic salts, heavy metals, and chemical agents. To achieve zero discharge of industrial wastewater, concentrated brine must be treated comprehensively and effectively. The core of industrial concentrated brine desalination lies in water-salt separation. Existing mainstream desalination methods can be divided into three types: thermally driven evaporation technology, pressure-driven membrane desalination technology, and freeze crystallization precipitation. However, these methods are highly dependent on large-scale power and heat facilities, requiring the consumption of large amounts of heat and electricity, which will exacerbate environmental pollution and the greenhouse effect. Production capacity and distribution locations are also limited. Moreover, salt contamination of equipment leads to extremely high equipment maintenance costs, which has become a common problem in the traditional desalination field.

[0003] To meet increasingly stringent emission requirements, solar-driven interfacial evaporation technology has emerged as a new desalination technology. Its core lies in utilizing photothermal materials to absorb sunlight and convert it into heat energy, thereby promoting the efficient evaporation of interfacial liquid water into water vapor. Therefore, different photothermal materials have become a research hotspot. Among them, graphite-like C3N4 exhibits excellent photothermal performance. Currently, C3N4 is mostly prepared using melamine, ethylenediamine, etc. as nitrogen sources. After condensation or heating, dense two-dimensional g-C3N4 is obtained. However, its reflection loss is high, its absorption spectrum range is relatively limited, its vapor escape channels are few, and its evaporation performance is poor. Summary of the Invention

[0004] This application provides a method for preparing porous nitrogen-containing carbon materials, which solves the problems of high reflection loss, few vapor escape channels, and limited absorption spectrum range in existing nitrogen-containing carbon materials.

[0005] To address the aforementioned technical problems, this application provides a method for preparing porous nitrogen-containing carbon materials, comprising four steps S1-S4. Step S1 involves measuring 0.5-2 mL of ethanolamine, 0.5-2 mL of terpineol, 1-3 mL of carbon tetrachloride, 1-3 mL of tert-butanol, and 0.5-1.0 g of mesoporous molecular sieve. Step S2 involves mixing the ethanolamine, carbon tetrachloride, tert-butanol, terpineol, and mesoporous molecular sieve, and then heating the mixture in an oil bath at 90°C. After 6 hours, the product is dried at 120°C for 12 hours to obtain the initial product. In step S3, the initial product is placed in a tube furnace, argon gas is continuously introduced into the tube furnace, and the temperature of the tube furnace is controlled at 400-900°C to carbonize the initial product and obtain a nitrogen-containing carbon product with molecular sieve. In step S4, the nitrogen-containing carbon product is cleaned with 5% hydrofluoric acid at least 10 times, and then vacuum dried at 100°C for 10 hours to remove the mesoporous molecular sieve and obtain a porous nitrogen-containing carbon material.

[0006] Preferably, the ethanolamine, carbon tetrachloride, tert-butanol, and terpineol are all 1 mL each, and the mesoporous molecular sieve is 0.8 g.

[0007] Preferably, the temperature of the tubular furnace is 700-900℃.

[0008] Ideally, the temperature of the tubular furnace is 900°C.

[0009] Furthermore, the mesoporous molecular sieve is SBA-15 molecular sieve.

[0010] Furthermore, after obtaining the porous nitrogen-containing carbon material, the process further includes:

[0011] The thermal evaporation performance and light absorption capacity of the porous nitrogen-containing carbon material were tested.

[0012] Compared with existing technologies, this application provides a method for preparing porous nitrogen-based carbon materials. The raw materials used are ethanolamine, carbon tetrachloride, tert-butanol, and terpineol. These four substances are mixed with mesoporous molecular sieves, heated in an oil bath, and dried to obtain a preliminary crude nitrogen-based carbon product. Then, carbonization is carried out in a tube furnace at a temperature controlled at 400-900℃ to completely carbonize the unreacted ethanolamine, carbon tetrachloride, tert-butanol, and terpineol in the crude nitrogen-based carbon product. Subsequently, the material is repeatedly washed with hydrofluoric acid and vacuum dried to obtain the porous nitrogen-based carbon material. The selection of raw materials and the control of carbonization temperature result in the final porous nitrogen-based carbon material having a large number of porous structures, a large specific surface area, increased vapor escape channels, and decreased light reflectivity, exhibiting good light absorption performance, an expanded absorption spectrum range, and enhanced absorption capacity. Therefore, using this porous nitrogen-based carbon material for desalination improves both the evaporation rate and the light conversion rate. Attached Figure Description

[0013] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0014] Figure 1 The ultraviolet absorption spectra of porous nitrogen-containing carbon materials prepared at different tube furnace temperatures provided by this invention. Detailed Implementation

[0015] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0016] The core of this application is to provide a method for preparing porous nitrogen-containing carbon materials, which can solve the problems of high reflection loss, few vapor escape channels, and limited absorption spectrum range in existing nitrogen-containing carbon materials.

[0017] Figure 1 The ultraviolet absorption spectra of porous nitrogen-containing carbon materials prepared in a tube furnace at temperatures of 400℃, 500℃, 600℃, 700℃, 800℃, and 900℃, as provided in embodiments of the present invention, are shown in Table 1 and... Figure 1 As shown:

[0018] Example 1

[0019] A method for preparing porous nitrogen-containing carbon material involves first measuring 1 mL of ethanolamine, 1 mL of carbon tetrachloride, 1 mL of tert-butanol, 1 mL of terpineol, and 0.8 g of SBA-15 molecular sieve, with the SBA-15 molecular sieve serving as a template agent. Next, the ethanolamine, carbon tetrachloride, tert-butanol, terpineol, and SBA-15 molecular sieve are mixed and heated in an oil bath at 90°C for 6 hours, followed by drying at 120°C for 12 hours to obtain the initial nitrogen-containing carbon product. Then, the initial nitrogen-containing carbon product is placed in a tube furnace, and argon gas is continuously introduced into the furnace. The initial nitrogen-containing carbon product was carbonized at controlled temperatures of 400℃, 500℃, 600℃, 700℃, 800℃, and 900℃ in a tubular furnace. Unreacted ethanolamine, carbon tetrachloride, tert-butanol, and terpineol were completely carbonized, yielding nitrogen-containing carbon products containing only molecular sieves at each temperature. Finally, each molecular sieve-containing nitrogen-containing carbon product was washed 10 times with 5% hydrofluoric acid and then vacuum-dried at 100℃ for 10 hours, ultimately obtaining six porous nitrogen-containing carbon materials at different carbonization temperatures. Preferably, to ensure the performance of each porous nitrogen-containing carbon material, after obtaining the porous nitrogen-containing carbon material, the thermal evaporation performance and light absorption capacity of the porous nitrogen-containing carbon material are tested.

[0020] Example 2

[0021] A method for preparing porous nitrogen-containing carbon materials involves first measuring 2 mL of ethanolamine, 2 mL of carbon tetrachloride, 2 mL of tert-butanol, 2 mL of terpineol, and 0.8 g of SBA-15 molecular sieve. These materials are mixed and heated in an oil bath at 90°C for 6 hours, followed by drying at 120°C for 12 hours to obtain an initial nitrogen-containing carbon product. Then, the initial nitrogen-containing carbon product is placed in a tube furnace, and argon gas is continuously introduced into the furnace. The furnace temperature is controlled at 400°C, 500°C, 600°C, 700°C, 800°C, and 900°C to carbonize the initial nitrogen-containing carbon product, obtaining nitrogen-containing carbon products containing only molecular sieves at different temperatures. Finally, each nitrogen-containing carbon product containing only molecular sieves is washed 10 times with 5% hydrofluoric acid and then vacuum dried at 100°C for 10 hours, ultimately obtaining six porous nitrogen-containing carbon materials obtained at different carbonization temperatures.

[0022] Example 3

[0023] A method for preparing porous nitrogen-containing carbon materials involves first measuring 0.5 mL of ethanolamine, 0.5 mL of carbon tetrachloride, 0.5 mL of tert-butanol, 0.5 mL of terpineol, and 0.8 g of SBA-15 molecular sieve. These materials are mixed and heated in an oil bath at 90°C for 6 hours, followed by drying at 120°C for 12 hours to obtain an initial nitrogen-containing carbon product. Then, the initial nitrogen-containing carbon product is placed in a tube furnace, and argon gas is continuously introduced into the furnace. The furnace temperature is controlled at 400°C, 500°C, 600°C, 700°C, 800°C, and 900°C to carbonize the initial nitrogen-containing carbon product, obtaining nitrogen-containing carbon products containing only molecular sieves at different temperatures. Finally, each nitrogen-containing carbon product containing only molecular sieves is washed 10 times with 5% hydrofluoric acid and then vacuum dried at 100°C for 10 hours, ultimately obtaining six porous nitrogen-containing carbon materials obtained at different carbonization temperatures.

[0024] Example 4

[0025] A method for preparing porous nitrogen-containing carbon materials involves first measuring 2 mL of ethanolamine, 2 mL of carbon tetrachloride, and 0.8 g of SBA-15 molecular sieve. These materials are mixed and heated in an oil bath at 90°C for 6 hours, followed by drying at 120°C for 12 hours to obtain an initial nitrogen-containing carbon product. Then, the initial nitrogen-containing carbon product is placed in a tube furnace, and argon gas is continuously introduced into the furnace. The furnace temperature is controlled at 400°C, 500°C, 600°C, 700°C, 800°C, and 900°C to carbonize the initial nitrogen-containing carbon product, obtaining nitrogen-containing carbon products containing only molecular sieves at different temperatures. Finally, each nitrogen-containing carbon product containing only molecular sieves is washed 10 times with 5% hydrofluoric acid and then vacuum dried at 100°C for 10 hours, ultimately obtaining six porous nitrogen-containing carbon materials obtained at different carbonization temperatures.

[0026] Example 5

[0027] A method for preparing porous nitrogen-containing carbon materials involves first measuring 1 mL of ethanolamine, 1 mL of carbon tetrachloride, and 0.8 g of SBA-15 molecular sieve. These materials are then mixed and heated in an oil bath at 90°C for 6 hours, followed by drying at 120°C for 12 hours to obtain an initial nitrogen-containing carbon product. Next, the initial nitrogen-containing carbon product is placed in a tube furnace, and argon gas is continuously introduced into the furnace. The furnace temperature is controlled at 400°C, 500°C, 600°C, 700°C, 800°C, and 900°C to carbonize the initial nitrogen-containing carbon product, obtaining nitrogen-containing carbon products containing only molecular sieves at different temperatures. Finally, each nitrogen-containing carbon product containing only molecular sieves is washed 10 times with 5% hydrofluoric acid and then vacuum dried at 100°C for 10 hours, ultimately obtaining six porous nitrogen-containing carbon materials obtained at different carbonization temperatures.

[0028] To facilitate a better understanding of this solution by those skilled in the art, six porous nitrogen-carbon materials with the best performance prepared under the conditions of Example 1 are selected below, and their performance is verified by specific experiments.

[0029] The experimental verification process was as follows: 50 mg of the porous nitrogen-carbon material prepared in Example 1 at 400°C in a tube furnace was weighed and added to 1000 mL of distilled water. The mixture was ultrasonically dissolved for 2 hours to ensure complete dissolution of the porous nitrogen-carbon material powder. Next, 50 mL of the porous nitrogen-carbon material solution was placed in a small beaker, and 1 mL of a hydrophobic reagent was added. The remaining 50 mL of the porous nitrogen-carbon material solution was placed on a stirrer and vigorously stirred to maintain a uniform dispersion for future use. Then, the solution in the small beaker was filtered onto filter paper using a vacuum filtration device, ensuring the porous nitrogen-carbon material solution was evenly spread on the filter paper. The filter paper was cut into squares with sides of 2 cm and laid flat on a homemade evaporator filled with seawater. To ensure optimal capillary action, the sample must be completely in contact with the absorbent cloth. A balance connected to a computer was turned on to record the mass change. When testing the thermal evaporation performance of porous nitrogen-containing carbon materials, the light source device was preheated for at least half an hour. The light power was adjusted by regulating the lifting platform and current via buttons on the bottom of the homemade evaporator light source. The homemade evaporator, lined with filter paper, was placed under a xenon lamp. The distance between the filter paper surface and the lamp source was determined using a power meter. Temperature was recorded starting at 0 seconds. For the first 5 minutes, due to the rapid temperature change, records were taken every 10 seconds. After 5 minutes, the temperature stabilized, and records were taken every 5 minutes. After 30 minutes, the temperature stabilized further, and records were taken every 30 minutes. The illumination time lasted 125 minutes. Since the evaporating mass increases, the remaining mass decreases, resulting in maximum and minimum values ​​at each moment. Therefore, 360 data points showing regular changes in the computer-recorded data were analyzed (m...). max -m min The calculation was performed by taking different values ​​for each experiment and calculating three times. Finally, the average value was obtained, and it was determined that the surface temperature of the porous nitrogen-containing carbon material prepared at a tube furnace temperature of 400℃ stabilized at 47℃ after 90 minutes of light irradiation.

[0030] Furthermore, the ultraviolet-visible diffuse reflectance spectrum of the porous nitrogen-atomized carbon material was measured using a spectrometer, which showed that the porous nitrogen-atomized carbon material has a certain absorption capacity for light in the range of about 300nm-800nm, and exhibits the strongest absorption capacity in the range of 400nm-500nm.

[0031] 50 mg of the porous nitrogen-carbon material from Example 1 was weighed out. This porous nitrogen-carbon material was prepared in a tube furnace at 500°C. Its thermal evaporation performance was tested using the same experimental method as described above. The results showed that after 90 minutes of illumination, the surface temperature of the porous nitrogen-carbon material stabilized at 47°C. Furthermore, the ultraviolet-visible diffuse reflectance spectrum of this porous nitrogen-carbon material, measured by a spectrometer, showed that it possessed a certain absorption capacity for light in the range of approximately 300 nm to 800 nm, exhibiting the strongest absorption capacity in the range of 400 nm to 550 nm. This absorption capacity was better than that of the porous nitrogen-carbon material prepared at 400°C.

[0032] 50 mg of the porous nitrogen-carbon material from Example 1 was weighed out. This porous nitrogen-carbon material was prepared in a tube furnace at 600°C. Its thermal evaporation performance was tested using the same experimental method as described above. After 90 minutes of illumination, the surface temperature of the porous nitrogen-carbon material stabilized at 47.6°C. Furthermore, the ultraviolet-visible diffuse reflectance spectrum of this porous nitrogen-carbon material, measured by a spectrometer, showed that it possessed a certain absorption capacity for light in the range of approximately 300 nm to 800 nm, exhibiting the strongest absorption capacity in the 400 nm to 600 nm range. Compared to the porous nitrogen-carbon materials prepared at 400°C and 500°C, it exhibited better absorption capacity and a more enhanced absorption range for visible light.

[0033] 50 mg of the porous nitrogen-carbon material from Example 1 was weighed out. This porous nitrogen-carbon material was prepared in a tube furnace at 700°C. The thermal evaporation performance of the porous nitrogen-carbon material was tested using the same experimental method as described above. After irradiation for 90 minutes, the surface temperature of the porous nitrogen-carbon material stabilized at 46.5°C. Furthermore, the ultraviolet-visible diffuse reflectance spectrum of the porous nitrogen-carbon material measured by a spectrometer showed that it has strong absorption capacity in the light range of approximately 300 nm to 850 nm, exhibiting the strongest absorption capacity in the 500 nm to 850 nm range. Compared to porous nitrogen-carbon materials prepared at 400°C, 500°C, and 600°C, it has better absorption capacity and a significantly enhanced absorption range for visible light.

[0034] 50 mg of the porous nitrogen-carbon material from Example 1 was weighed out. This porous nitrogen-carbon material was prepared in a tube furnace at 800°C. The thermal evaporation performance of the porous nitrogen-carbon material was tested using the same experimental method as described above. After 90 minutes of illumination, the surface temperature of the porous nitrogen-carbon material stabilized at 45.8°C. Furthermore, the ultraviolet-visible diffuse reflectance spectrum of the porous nitrogen-carbon material measured by a spectrometer showed that it has strong absorption capacity in the light range of approximately 300 nm to 850 nm, exhibiting the strongest absorption capacity in the 500 nm to 850 nm range. Compared to porous nitrogen-carbon materials prepared at 400°C, 500°C, 600°C, and 700°C, it has better absorption capacity and an enhanced absorption range for visible light.

[0035] 50 mg of the porous nitrogen-carbon material from Example 1 was weighed. This porous nitrogen-carbon material was prepared in a tube furnace at 900°C. Its thermal evaporation performance was tested using the same experimental method as described above. After 90 minutes of illumination, the surface temperature of the porous nitrogen-carbon material stabilized at 47°C. Furthermore, the UV-Vis diffuse reflectance spectrum of this porous nitrogen-carbon material, measured by a spectrometer, showed strong absorption capacity for light in the range of approximately 300 nm to 850 nm, exhibiting the strongest absorption capacity in the 500 nm to 850 nm range. Compared to porous nitrogen-carbon materials prepared at 400°C, 500°C, 600°C, 700°C, and 800°C, the porous nitrogen-carbon material carbonized at 900°C showed significantly improved spectral absorption range and photothermal conversion efficiency. This comparison indicates that the porous nitrogen-carbon material exhibits the strongest absorption capacity, a result consistent with the material's black color.

[0036] To enable those skilled in the art to more clearly compare the performance differences of the porous nitrogen-carbon materials in different embodiments, the surface temperature data of the porous nitrogen-carbon materials prepared at different tube furnace temperatures under illumination are statistically compared in tabular form below. Table 1 shows the surface temperature data of the porous nitrogen-carbon materials prepared at tube furnace temperatures of 400℃, 500℃, 600℃, 700℃, 800℃, and 900℃ respectively, provided in Embodiment 1 of the present invention.

[0037] Tubular furnace temperature / °C Stable surface temperature at 90 minutes / °C 400 47 500 47 600 47.6 700 46.5 800 45.8 900 47

[0038] Porous nitrogen-based carbon materials can convert solar energy into heat energy after absorbing infrared spectra. The stronger the light absorption capacity, the better the water evaporation performance of the material. In the above six test experiments, an 800nm ​​filter was added so that the porous nitrogen-based carbon material only absorbed infrared spectra, and it still showed a certain water evaporation performance. The porous structure formed by the preparation method of this application promotes the transport speed of water in the interfacial evaporation process, thereby improving the water evaporation rate. The solar thermal efficiency reaches 95%, the evaporation rate of seawater (25wt.% NaCl) reaches 2.0 kg·m-2·h-1, and the surface temperature of the porous nitrogen-based carbon material under illumination can reach up to 47.6℃.

[0039] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and incorporate common knowledge or customary techniques in the art disclosed herein. The specification and examples are to be considered exemplary only, and the true scope of this application is indicated by the claims.

[0040] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The embodiments of this application described above do not constitute a limitation on the scope of protection of this application.

Claims

1. A method for preparing a porous nitrogen-containing carbon material, characterized in that, Includes the following steps: S1. Measure 0.5-2 mL of ethanolamine, 0.5-2 mL of terpineol, 1-3 mL of carbon tetrachloride, 1-3 mL of tert-butanol, and 0.5-1.0 g of mesoporous molecular sieve. S2. The ethanolamine, carbon tetrachloride, tert-butanol, terpineol and the mesoporous molecular sieve are mixed and heated in an oil bath at 90°C for 6 hours, and then dried at 120°C for 12 hours to obtain the initial product. S3. Place the initial product in a tube furnace, continuously introduce argon gas into the tube furnace, and control the temperature of the tube furnace to 400-900℃ to carbonize the initial product and obtain a nitrogen-containing carbon product with molecular sieves. S4. After cleaning the nitrogen-containing carbon product with 5% hydrofluoric acid at least 10 times, vacuum dry it at 100°C for 10 hours to remove the mesoporous molecular sieve and obtain porous nitrogen-containing carbon material.

2. The method for preparing a porous nitrogen-containing carbon material according to claim 1, characterized in that, The ethanolamine, carbon tetrachloride, tert-butanol, and terpineol are each 1 mL, and the mesoporous molecular sieve is 0.8 g.

3. The method for preparing a porous nitrogen-containing carbon material according to claim 2, characterized in that, The temperature of the tubular furnace is 700-900℃.

4. The method for preparing a porous nitrogen-containing carbon material according to claim 3, characterized in that, The temperature of the tubular furnace is 900℃.

5. The method for preparing a porous nitrogen-containing carbon material according to claim 1, characterized in that, The mesoporous molecular sieve is SBA-15 molecular sieve.

6. The method for preparing a porous nitrogen-containing carbon material according to claim 1, characterized in that, After obtaining the porous nitrogen-containing carbon material, the process further includes: The thermal evaporation performance and light absorption capacity of the porous nitrogen-containing carbon material were tested.

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