A carbonized / sulfonated integrated corncob-based photothermal conversion device and its preparation method and application

Abstract

The present invention discloses a carbonization / sulfonation integrated corncob-based photothermal conversion device and its preparation method and application, belonging to the technical field of solar seawater desalination. The carbonization / sulfonation integrated corncob-based photothermal conversion device is prepared by using corncobs as raw materials and performing a hydrothermal reaction with sulfuric acid to perform in-situ carbonization and sulfonation in one step. The carbonization / sulfonation integrated corncob-based photothermal conversion device of the present invention has high evaporation efficiency and strong salt resistance. The preparation method of the carbonization / sulfonation integrated corncob-based photothermal conversion device of the present invention has mild reaction conditions and is environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar desalination, and relates to the fields of solar thermal conversion, seawater desalination and new materials, and in particular to a carbonized / sulfonated integrated corncob-based thermal conversion device and a preparation method and application thereof. Background Art

[0002] Biomass-based carbon materials are widely used in solar desalination. For example, Zhu Jia's research group carbonized mushrooms at 500℃ in an argon atmosphere for 12 hours to obtain carbonized mushrooms, which were then used for solar desalination (Adv. Mater. 2017, 1606762, 1–5). Because the natural umbrella-shaped structure of mushrooms provides effective water supply channels and evaporation surfaces, they have strong thermal localization characteristics and produce lower heat conduction and radiation losses during the evaporation process. Zhao Zongbin et al. carbonized corn cobs at 450℃ in a nitrogen atmosphere for 1 hour to obtain carbonized corn cobs for solar desalination (Carbon. 2021, 179, 337–347). They found that the natural porous structure of corn cobs provides effective light absorption and side evaporation escape channels, and has strong light-to-heat conversion characteristics. The above studies all used biomass-based carbon materials treated with high-temperature carbonization as evaporators, and proposed that the unique natural structure of biomass is conducive to solar desalination. However, existing research often has the following problems: (1) The high-temperature carbonization process of biomass consumes a lot of energy and emits carbonized tail gas containing carbon, hydrogen and oxygen, which causes environmental pollution and is not conducive to large-scale application; (2) After the carbonization treatment, the hydrophilic groups on the surface of the biomass base are lost in large quantities. During the continuous evaporation of seawater, the wettability of the evaporation device decreases, the water supply is insufficient, and the evaporation efficiency is reduced. Therefore, adjusting the balance between the heat absorbed by the photothermal conversion device and the energy required for evaporation water supply is one of the effective ways to improve solar desalination.

[0003] Recently, Arne Thomas designed a hydrophilic sulfonic acid covalent organic framework / hydrophobic reduced graphene oxide dual-region hydrogel as a solar evaporation device (J.Am.Chem.Soc.2022, 144, 3083–3090). By precisely controlling the hydrophilic (sulfonic acid group)-hydrophobic dual regions, the water wettability was adjusted to optimize the water content required for the evaporation device and reduce the evaporation energy requirement. The results showed that the sulfonic acid group could change the water state of the evaporation device, and the solar desalination rate reached 3.69 kg·m -2 ·h -1 They used graphene oxide as raw material, adjusted the content of covalent organic framework with sulfonic acid groups, and formed a controllable water state gel through hydrothermal reaction. This method has problems such as expensive raw materials and poor product structural stability. Summary of the invention

[0004] In view of the problems of high equipment requirements, complicated steps, and high prices in the process of preparing solar thermal conversion devices, the present invention provides a carbonized / sulfonated integrated corn cob-based photothermal conversion device and its preparation method and application. The steps are to use hydrothermal reaction, concentrated sulfuric acid as a dehydrating agent and a sulfonating agent, preferably to achieve in-situ carbonization and sulfonation of corn cobs in a liquid phase environment below 200°C, and prepare a carbonized corn cob with sulfonic acid groups in one step. Wash it to neutrality, place it on the horizontal surface of seawater or concentrated brine, and prepare fresh water under sunlight. Compared with traditional carbonized corn cobs, the carbonized / sulfonated integrated corn cob-based photothermal conversion device can adjust the balance of photothermal conversion and water transport, thereby improving the efficiency of solar seawater desalination. The present invention uses solid waste corn cobs as raw materials, and uses a hydrothermal method to prepare a carbonized / sulfonated integrated corn cob-based photothermal conversion device in one step, saving raw material costs, reducing equipment energy consumption and environmental burden, and providing an economical and reliable technical route for biomass-based photothermal conversion devices.

[0005] The first aspect of the present invention is to disclose a carbonization / sulfonation integrated corncob-based photothermal conversion device, which is prepared by using corncob as a raw material and performing a hydrothermal reaction with sulfuric acid to perform in-situ carbonization and sulfonation in one step.

[0006] The corncob may be in the form of a whole, a block or a sheet.

[0007] In some embodiments of the present invention, the temperature of the hydrothermal reaction is lower than 400°C, preferably lower than 250°C.

[0008] In some embodiments of the present invention, the sulfuric acid is concentrated sulfuric acid, and the weight ratio of the corn cob to the concentrated sulfuric acid is 1:(0.1-15), preferably 1:(0.3-10).

[0009] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 180-200° C. and the time is 4-12 h.

[0010] The second aspect of the present invention is to disclose a method for preparing the carbonization / sulfonation integrated corncob-based photothermal conversion device described in the first aspect, including the steps of S03, using corncob as raw material, and performing a hydrothermal reaction with sulfuric acid to perform in-situ carbonization and sulfonation in one step.

[0011] In some embodiments of the present invention, the temperature of the hydrothermal reaction is lower than 400°C, preferably lower than 250°C.

[0012] In some embodiments of the present invention, the sulfuric acid is concentrated sulfuric acid, and the weight ratio of the corn cob to the concentrated sulfuric acid is 1:(0.1-15), preferably 1:(0.3-10).

[0013] In some embodiments of the present invention, the hydrothermal reaction temperature is 160-220° C., and the time is 1-12 h, preferably 180-200° C., and the time is 4-12 h.

[0014] In some embodiments of the present invention, the method further comprises the step of soaking the corn cob in sulfuric acid in S02, wherein the soaking time is preferably 12-24 hours.

[0015] In some embodiments of the present invention, the method further comprises S01, wherein the corn cob is soaked in water, rinsed and dried, preferably soaked in deionized water for 6-24 hours at a drying temperature of 40-85°C.

[0016] In some embodiments of the present invention, the corn cob is soaked in deionized water and rinsed repeatedly 2-5 times.

[0017] In some embodiments of the present invention, S04 is further included, wherein after the hydrothermal reaction is completed, the steps of cooling, washing with deionized water until neutral, and drying are performed, and preferably the drying temperature is 40-120° C. and the drying time is 12-24 hours.

[0018] The third aspect of the present invention is to disclose the use of the carbonized / sulfonated integrated corncob-based photothermal conversion device described in the first aspect in evaporating liquid, preferably the liquid is one or more of fresh water, sea water, and concentrated brine.

[0019] The fresh water may be surface water, tap water, or deionized water. The salinity of the seawater is approximately 3.5 wt% NaCl, and the salinity of the concentrated brine is approximately 3.5-20 wt% NaCl.

[0020] Beneficial effects of the present invention:

[0021] (1) Mild reaction conditions: Generally, biomass-based carbon materials need to be calcined at 500°C in an inert atmosphere, which has specific requirements for equipment and is not conducive to large-scale application. The present invention only requires a high-pressure reactor and uses concentrated sulfuric acid as a dehydrating agent and a sulfonating agent to achieve in-situ carbonization and sulfonation of corn cobs in a liquid phase environment below 200°C, and prepares carbonized corn cobs with sulfonic acid groups in one step, which is easy to prepare and has wide applicability.

[0022] (2) Environmentally friendly: The high-temperature carbonization process of biomass will emit carbonized tail gas containing carbon, hydrogen and oxygen, causing environmental pollution. However, the hydrothermal reaction does not emit polluting gases under closed conditions, reducing environmental pollution.

[0023] (3) High evaporation efficiency: After carbonization, the hydrophilic groups on the biomass-based surface are largely lost. During the continuous evaporation of seawater, the wettability of the evaporation device decreases, the water supply is insufficient, and the evaporation efficiency is reduced. The carbonized / sulfonated integrated corncob-based photothermal conversion device prepared in one step by the present invention can effectively absorb sunlight, and the sulfonated groups can adjust the water state of the evaporation device. The two can effectively adjust the balance between the heat absorbed by the photothermal system and the energy required for evaporation and water supply, thereby improving the efficiency of solar desalination.

[0024] (4) Strong salt resistance: In the process of solar desalination, the natural structure of carbonized / sulfonated integrated corncobs can effectively dilute the concentration of seawater, while the negatively charged hydrophilic -SO 3 H / -SO 3 - The group can effectively intercept Cl - , so that Na + With Cl - Separation to achieve stability, controllability and salt resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0026] Figure 1 This is a digital photo of the carbonized / sulfonated integrated corncob-based photothermal conversion device prepared in Example 1.

[0027] Figure 2 This is a digital photo of the carbonized / sulfonated integrated corncob-based photothermal conversion device prepared in Example 1 during the solar seawater desalination process.

[0028] Figure 3 This is a bar graph of the pure water evaporation rate of the carbonized / sulfonated integrated corncob-based photothermal conversion device prepared in Example 1 under a 1-sun illumination intensity.

[0029] Figure 4 This is a bar graph of the seawater evaporation rate of the carbonized / sulfonated integrated corncob-based photothermal conversion device prepared in Example 2 under a 1-sun illumination intensity.

[0030] Figure 5 This is a bar graph of the evaporation rate of concentrated brine for the carbonized / sulfonated integrated corncob-based photothermal conversion device prepared in Example 3 under a light intensity of 1 sun.

[0031] Figure 6 This is a bar graph of the evaporation rate of concentrated brine for the carbonized / sulfonated integrated corncob-based photothermal conversion device prepared in Example 4 under a light intensity of 1 sun.

[0032] in, Figure 3 to Figure 6 The carbonized corn cobs were calcined at 450 °C for 1.5 h in a nitrogen atmosphere. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0034] Unless otherwise specified, the examples and comparative examples are parallel tests with the same components, component contents, preparation steps and preparation parameters.

[0035] In step (b), the product of (a) is a mixture of soaked corn cobs and analytically pure sulfuric acid.

[0036] In step (d), the solution is a liquid for evaporation test. The pure water contains 0 wt% NaCl, the seawater contains 3.5 wt% NaCl, and the concentrated brine contains 20 wt% NaCl.

[0037] Example 1

[0038] A method for preparing a carbonization / sulfonation integrated corncob-based photothermal conversion device comprises the following steps:

[0039] (a) Soak natural corn cobs with a height of 1 cm in deionized water for 6 hours, rinse with new water, and repeat three times. Dry at a drying temperature of 80°C.

[0040] (b) soaking the product of (a) in an analytically pure strong acid at a mass ratio of 1:10 for 12 hours, wherein the analytically pure strong acid used is sulfuric acid;

[0041] (c) placing the product of (b) in a hydrothermal reactor, reacting at 200° C. for 6 h, cooling to room temperature, washing with deionized water until neutral, and then drying at 80° C. for 12 h to obtain a carbonized / sulfonated integrated corncob-based photothermal conversion device; Figure 1 As shown;

[0042] (d) placing the product of (c) on polystyrene insulation foam, with the bottom in contact with the water transfer sponge and the rest of the part completely exposed to the air, to form a solar desalination device with an exposed height of 1 cm; Figure 2 As shown;

[0043] (e) The product of (d) is exposed to light. Water is driven by capillary forces and hydrophilic functional groups to be transported from bottom to top along the macroporous channels between the carbon particles. The continuous evaporation of water on the carbon surface forms a continuous flow of water inside the carbon. Water is vaporized from the macroporous channels on the top and sides of the carbonized / sulfonated integrated corn cob base.

[0044] Experiment: The carbonized / sulfonated integrated corncob-based photothermal conversion device of Example 1 of the present invention was used to test the performance of solar pure water evaporation. Figure 3 As shown in the figure, under the illumination intensity of 1 sun, the evaporation rate of pure water in 1 cm corn cob calcined at traditional high temperature is 1.20 kg·m -2 ·h -1 The pure water evaporation rate of the 1 cm carbonized / sulfonated integrated corncob-based photothermal conversion device is 1.32 kg·m -2 ·h -1 , indicating that the hydrophilicity and light absorption of carbonized / sulfonated integrated corncob are higher than those of carbonized corncob. The other evaporation rate data are shown in Table 1.

[0045] Example 2

[0046] A method for preparing a carbonization / sulfonation integrated corncob-based photothermal conversion device comprises the following steps:

[0047] (a) Soak natural corn cobs with a height of 7 cm in deionized water for 6 hours, rinse with water, and repeat three times. Dry at a drying temperature of 80°C.

[0048] (b) soaking the product of (a) in an analytically pure strong acid at a mass ratio of 1:10 for 12 hours, wherein the analytically pure strong acid used is sulfuric acid;

[0049] (c) placing the product of (b) in a hydrothermal reactor, reacting at 200° C. for 6 h, cooling to room temperature, washing with deionized water until neutral, and then drying at 80° C. for 12 h to obtain a carbonized / sulfonated integrated corncob-based photothermal conversion device;

[0050] (d) placing the product of (c) on polystyrene insulation foam, with the bottom in contact with the water transfer sponge and the rest of the part completely exposed to the air, to form a solar desalination device with an exposed height of 7 cm;

[0051] (e) The product of (d) is exposed to light. Water is driven by capillary forces and hydrophilic functional groups to be transported from bottom to top along the macroporous channels between the carbon particles. The continuous evaporation of water on the carbon surface forms a continuous flow of water inside the carbon. Water is vaporized from the macroporous channels on the top and sides of the carbonized / sulfonated integrated corn cob base.

[0052] Experiment: The carbonized / sulfonated integrated corncob-based photothermal conversion device of Example 2 of the present invention was used to test the performance of solar pure water evaporation. Figure 4 As shown in Figure 2, the evaporation rate of pure water from 7 cm corn cob calcined at a conventional high temperature under 1 sun intensity is 1.86 kg·m -2 ·h -1 The 7 cm carbonized / sulfonated integrated corncob-based photothermal conversion device is 2.56 kg·m -2 ·h -1 The evaporation rate of pure water is much higher than 1 cm, indicating that side evaporation is beneficial to solar desalination. The other evaporation rate data are shown in Table 1.

[0053] Example 3

[0054] A method for preparing a carbonization / sulfonation integrated corncob-based photothermal conversion device comprises the following steps:

[0055] (a) Soak natural corn cobs with a height of 7 cm in deionized water for 12 hours, rinse with water, and repeat three times. Dry at a drying temperature of 80°C.

[0056] (b) soaking the product of (a) with an analytically pure strong acid in a mass ratio of 1:5 for 24 hours, wherein the analytically pure strong acid used is sulfuric acid;

[0057] (c) placing the product of (b) in a hydrothermal reactor, reacting at 200° C. for 12 h, cooling to room temperature, washing with deionized water until neutral, and then drying at 80° C. for 12 h to obtain a carbonized / sulfonated integrated corncob-based photothermal conversion device;

[0058] (d) placing the product of (c) on polystyrene insulation foam, with the bottom in contact with the water transfer sponge and the rest of the part completely exposed to the air, to form a solar desalination device with an exposed height of 7 cm;

[0059] (e) The product of (d) is exposed to light. Water is driven by capillary forces and hydrophilic functional groups to be transported from bottom to top along the macroporous channels between the carbon particles. The continuous evaporation of water on the carbon surface forms a continuous flow of water inside the carbon. Water is vaporized from the macroporous channels on the top and sides of the carbonized / sulfonated integrated corn cob base.

[0060] Experiment: The carbonized / sulfonated integrated corncob-based photothermal conversion device of Example 3 of the present invention was used to test the performance of solar seawater evaporation. Figure 5 As shown in Figure 2, the evaporation rate of corncob-based seawater calcined at a conventional high temperature under 1 sun intensity is 1.42 kg·m -2 ·h -1The seawater evaporation rate of the carbonized / sulfonated corncob-based photothermal conversion device is 2.13 kg·m -2 ·h -1 Although the evaporation rate of seawater is lower than that of pure water, the evaporation rate of carbonized / sulfonated integrated corncob-based seawater is still higher than that of traditional high-temperature calcined corncob-based seawater. The remaining evaporation rate data are shown in Table 1.

[0061] Example 4

[0062] A method for preparing a carbonization / sulfonation integrated corncob-based photothermal conversion device comprises the following steps:

[0063] (a) Soak natural corn cobs with a height of 7 cm in deionized water for 24 hours, rinse with new water, and repeat three times. Dry at a drying temperature of 80°C.

[0064] (b) soaking the product of (a) in an analytically pure strong acid at a mass ratio of 1:0.3 for 12 hours, wherein the analytically pure strong acid used is sulfuric acid;

[0065] (c) placing the product of (b) in a hydrothermal reactor, reacting at 180° C. for 2 h, cooling to room temperature, washing with deionized water until neutral, and then drying at 80° C. for 12 h to obtain a carbonized / sulfonated integrated corncob-based photothermal conversion device;

[0066] (d) placing the product of (c) on polystyrene insulation foam, with the bottom in contact with the water transfer sponge and the rest of the part completely exposed to the air, to form a solar desalination device with an exposed height of 7 cm;

[0067] (e) The product of (d) is exposed to light. Water is driven by capillary forces and hydrophilic functional groups to be transported from bottom to top along the macroporous channels between the carbon particles. The continuous evaporation of water on the carbon surface forms a continuous flow of water inside the carbon. Water is vaporized from the macroporous channels on the top and sides of the carbonized / sulfonated integrated corn cob base.

[0068] Experiment: The carbonization / sulfonation integrated corncob-based photothermal conversion device of Example 4 of the present invention was used to test the performance of solar concentrated brine evaporation. Figure 6 As shown in Figure 2, the evaporation rate of corncob-based concentrated brine calcined at a conventional high temperature under 1 sun intensity is 1.07 kg·m -2 ·h -1 The evaporation rate of concentrated brine in the carbonization / sulfonation integrated corncob-based photothermal conversion device is 1.85 kg·m -2 ·h -1Obviously, the evaporation rate of carbonized / sulfonated integrated corncob base during the continuous evaporation of different salinity solutions is higher than that of the traditional high-temperature calcined corncob base, indicating that the one-step hydrothermal reaction method is beneficial for the use of corncob base in solar desalination. The other evaporation rate data are shown in Table 1.

[0069] The evaporation rates of Examples 1 to 4 and carbonized corn cobs in pure water, seawater, and concentrated brine are shown in Table 1:

[0070] Table 1 Evaporation rate performance

[0071]

[0072] The results show that Example 1 is significantly better than the 450°C carbonized corn cob (1 cm), and Examples 2-4 are significantly better than the 450°C carbonized corn cob (7 cm). Among Examples 1-4, Examples 2-4 are significantly better than Example 1, and Example 4 is significantly better than Examples 2 and 3.

[0073] The preferred specific implementation modes and embodiments of the present invention are described in detail above, but the present invention is not limited to the above implementation modes and embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the concept of the present invention.

Claims

1. Application of a carbonized / sulfonated integrated corncob-based photothermal conversion device in evaporating liquids, wherein the carbonized / sulfonated integrated corncob-based photothermal conversion device is prepared by using corncobs as raw materials and performing a hydrothermal reaction with sulfuric acid to perform in-situ carbonization and sulfonation in one step.

2. The use according to claim 1, It is characterized in that The liquid is one or more of seawater and concentrated brine.

3. The use according to claim 1 or 2, It is characterized in that The temperature of the hydrothermal reaction is lower than 400°C.

4. The use according to claim 3, It is characterized in that The temperature of the hydrothermal reaction is lower than 250°C.

5. The use according to claim 1 or 2, It is characterized in that The sulfuric acid is concentrated sulfuric acid, and the weight ratio of the corn cob to the concentrated sulfuric acid is 1:(0.1-15).

6. The use according to claim 5, It is characterized in that The weight ratio of the corn cob to the concentrated sulfuric acid is 1:(0.3-10).

7. The use according to claim 1 or 2, It is characterized in that The temperature of the hydrothermal reaction is 160-220° C. and the time is 1-12 hours.

8. The use according to claim 1 or 2, It is characterized in that The temperature of the hydrothermal reaction is 180-200° C. and the time is 2-12 hours.

9. The use according to claim 1 or 2, It is characterized in that The method for preparing the carbonization / sulfonation integrated corncob-based photothermal conversion device comprises the step of soaking the corncob in sulfuric acid.

10. The use according to claim 9, It is characterized in that The soaking time is 12-24h.

11. The use according to claim 1 or 2, It is characterized in that The method comprises the steps of soaking the corn cob with water, washing and drying the corn cob.

12. The use according to claim 11, It is characterized in that Soak in deionized water for 6-24 hours and dry at 40-85℃.

13. The use according to claim 1 or 2, It is characterized in that The process also includes cooling, washing with deionized water until the reaction is neutral, and drying after the hydrothermal reaction is completed.

14. The use according to claim 13, It is characterized in that The drying temperature is 40-120°C and the drying time is 12-24h.

15. A method of evaporating a liquid, It is characterized in that Placing a carbonized / sulfonated integrated corncob-based photothermal conversion device on thermal insulation foam, wherein the bottom of the carbonized / sulfonated integrated corncob-based photothermal conversion device is in contact with a water-transporting sponge, and the rest of the device is exposed to the air; The carbonization / sulfonation integrated corncob-based photothermal conversion device is prepared by using corncobs as raw materials and performing hydrothermal reaction with sulfuric acid to achieve one-step in-situ carbonization and sulfonation.

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