Method for preparing three-dimensional graphene aerogel photo-thermal material through gamma ray irradiation

Abstract

The invention provides a method for preparing a three-dimensional graphene aerogel photo-thermal material through gamma ray irradiation, which comprises the following steps: uniformly mixing a graphene oxide aqueous solution and L-ascorbic acid, and then putting the mixture into a closed container for reduction reaction to form wet hydrogel; the wet hydrogel is washed and then solidified in liquid nitrogen, and three-dimensional graphene aerogel is obtained through low-temperature freeze drying; the three-dimensional graphene aerogel is irradiated through gamma rays, and the three-dimensional graphene aerogel photo-thermal material is obtained. By introducing gamma rays, the photo-thermal performance of the three-dimensional graphene aerogel material can be remarkably improved, the water evaporation rate of the three-dimensional graphene aerogel material is increased, and meanwhile the three-dimensional graphene aerogel material has excellent recycling performance and durability. The steps are simple, harmful substances are not generated, and the obtained product is high in stability, resistant to high temperature and easy to store and has practicability. The prepared three-dimensional graphene aerogel photo-thermal material can be applied to the fields of seawater desalination, sewage purification, wastewater treatment and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of photothermal materials, and particularly relates to a method for preparing a three-dimensional graphene aerogel photothermal material by gamma-ray irradiation. Background Art

[0002] In recent years, solar-driven interfacial evaporation technology (SIE) has received extensive attention. This technology utilizes the excellent light absorption and photothermal conversion capabilities of photothermal materials and the transpiration of water to transport a large amount of water from the bottom to the evaporation surface from bottom to top, and localize heat on its upper surface, enabling the rapid evaporation of water. After the steam condenses, purified water is obtained, and the waste is left in the remaining sewage or on the surface of the photothermal material, thus providing a new green, environmentally friendly, and energy-saving approach for seawater desalination, sewage purification, heavy metal recovery, etc. In the SIE technology, the performance of photothermal materials is the key to affecting interfacial evaporation. Although a large number of photothermal evaporation materials have been prepared, such as graphene materials, wood materials, sponge materials, etc., and have been used in fields such as seawater desalination, sewage treatment, wastewater purification, and heavy metal recovery, the development of high-performance methods for preparing photothermal materials remains a research hotspot at present. Summary of the Invention

[0003] (I) Technical Problems to be Solved

[0004] The present invention provides a method for preparing a three-dimensional graphene aerogel photothermal material by gamma-ray irradiation to solve the technical problem of how to improve the photothermal performance of graphene aerogel materials.

[0005] (II) Technical Solutions

[0006] To solve the above technical problems, the present invention provides a method for preparing a three-dimensional graphene aerogel photothermal material by gamma-ray irradiation. The method is as follows: an aqueous solution of graphene oxide is mixed with L-ascorbic acid evenly and then placed in a sealed container for a reduction reaction to form a wet hydrogel; after washing the wet hydrogel, it is solidified in liquid nitrogen, and through low-temperature freeze-drying, a three-dimensional graphene aerogel is obtained; by irradiating the three-dimensional graphene aerogel with gamma rays, a three-dimensional graphene aerogel photothermal material is obtained.

[0007] Further, the concentration of the aqueous solution of graphene oxide is 2 - 6 mg / mL.

[0008] Further, the mass ratio of graphene oxide to L-ascorbic acid is 1:(1 - 10).

[0009] Further, the reduction reaction is carried out at 80 °C for 6 h to form a wet hydrogel.

[0010] Further, the detergent used for washing the wet hydrogel is one or more of deionized water, ethanol, and tert-butanol.

[0011] Further, through Co 60 The gamma rays emitted by the radiation source irradiate the three-dimensional graphene aerogel.

[0012] Further, Co 60 The irradiation intensity of the radiation source is 30 - 80 Gy / h.

[0013] Further, the radiation dose received by the three-dimensional graphene aerogel under the irradiation of the Co 60 radiation source is 1 - 10 kGy.

[0014] (III) Beneficial effects

[0015] The present invention provides a method for preparing a three-dimensional graphene aerogel photothermal material by gamma-ray irradiation. The aqueous solution of graphene oxide and L-ascorbic acid are mixed evenly and then placed in a sealed container for a reduction reaction to form a wet hydrogel. After washing the wet hydrogel, it is solidified in liquid nitrogen and freeze-dried at low temperature to obtain a three-dimensional graphene aerogel. By irradiating the three-dimensional graphene aerogel with gamma rays, a three-dimensional graphene aerogel photothermal material is obtained. The present invention can significantly improve the photothermal performance of the three-dimensional graphene aerogel material and accelerate its water evaporation rate by introducing gamma rays. At the same time, it also has excellent recyclability and durability. The steps of the present invention are simple, no harmful substances are generated, the obtained product has high stability, is resistant to high temperature, is easy to store, and has practicability. The prepared three-dimensional graphene aerogel photothermal material can be applied to fields such as seawater desalination, sewage purification, and wastewater treatment. The photothermal evaporator prepared with the three-dimensional graphene aerogel photothermal material as the core material has excellent water evaporation performance and sewage treatment ability. Description of the drawings

[0016] Figure 1 SEM image of the three-dimensional black cylindrical GA aerogel prepared in Example 1;

[0017] Figure 2 Water evaporation rate diagram of the unirradiated three-dimensional graphene aerogel prepared in the example; In the figure: the abscissa is the sample, and the ordinate is the water evaporation rate, unit: kg / (m²·h); (1) pure water, (2) GA-3, (3) GA-6;

[0018] Figure 3 Water evaporation rate diagram of the three-dimensional graphene aerogel photothermal material prepared after gamma-ray irradiation in the example; In the figure: the abscissa is the sample, and the ordinate is the water evaporation rate unit: kg / (m²·h); (1) GA-3, (2) RGA-3, (3) GA-6, (4) RGA-6. Detailed implementation manners

[0019] To make the objectives, contents, and advantages of the present invention clearer, the following further describes the specific implementation manners of the present invention in detail with reference to the accompanying drawings and embodiments.

[0020] Example 1

[0021] The preparation method of the three-dimensional graphene aerogel photothermal material specifically includes the following steps:

[0022] (1) Prepare an aqueous solution of graphene oxide (GO) with a concentration of 3 mg / mL;

[0023] (2) Mix the GO aqueous solution and L-ascorbic acid evenly at a mass ratio of 1:3;

[0024] (3) Transfer the above solution to a sealed container, and perform high-temperature reduction at 80 °C for 6 h to synthesize a three-dimensional cylindrical wet hydrogel (GH); wash the GH multiple times with deionized water and tert-butanol alternately, put the washed GH into liquid nitrogen for freezing into a solid, and dry it in a freeze dryer at -99 °C for 48 h to obtain a three-dimensional black cylindrical GA aerogel, named GA-3; its scanning electron microscope photo is as Figure 1 shown.

[0025] (4) Under the condition that the intensity of the Co 60 radioactive source is 40 Gy / h, irradiate the above-prepared GA aerogel with gamma rays emitted by the Co 60 radioactive source for 1.5 kGy to obtain a three-dimensional graphene aerogel photothermal material, named RGA-3.

[0026] Take the aerogel materials before and after gamma-ray irradiation prepared in Example 1 for the interfacial water evaporation experiment under the illumination condition of simulated sunlight (1 sun).

[0027] (5) Fix the unirradiated aerogel material GA-3 wrapped with fiber paper and dug polystyrene heat insulation foam on a beaker filled with deionized water, place the beaker on a precision electronic balance, and place it under the irradiation of a 1 sun xenon lamp source. Record the mass change of the water body every 5 min under steady-state conditions (the total time is 90 min).

[0028] (6) Place a piece of irradiated three-dimensional graphene aerogel photothermal material RGA-3 in the above-built device, and record the mass change of the water body every 5 min under steady-state conditions (the total time is 90 min);

[0029] (7) Using the experimental data obtained in steps (5) and (6), calculate the water evaporation rate and energy conversion efficiency of the aerogel materials GA-3 and RGA-3 respectively. The calculation formulas for the water evaporation rate and energy conversion rate are shown in (1-1) and (1-2) respectively:

[0030] v = m / (S·t) (1-1)

[0031] η = (v·h lv ) / (C opt ·q i ) (1-2)

[0032] In the above formulas: m—the mass loss of water (kg); S—the light-irradiated evaporation area of the photothermal material (m 2 ); t—the light-irradiation time (h); v—the evaporation rate (kg·m -2 ·h -1 ); C opt —the light density (the value is 1); q i —the solar radiation power (1 kW·m-2); h lv —the total enthalpy required for water to be converted from liquid to vapor (J·g -1 )(here, the equivalent evaporation enthalpy of water in GA calculated by the dark experiment is selected as 1672.21 J·g -1 ).

[0033] It is experimentally measured that under the light intensity of 1 sun, the water evaporation rate of the unirradiated aerogel GA-3 is 2.702 Kg / (m 2 ·h), and the water evaporation rate of the irradiated aerogel RGA-3 can reach 4.80 Kg / (m 2 ·h).

[0034] Example 2

[0035] The preparation method of the three-dimensional graphene aerogel photothermal material specifically includes the following steps:

[0036] (1) Prepare an aqueous solution of graphene oxide (GO) with a concentration of 6 mg / mL;

[0037] (2) Mix the GO aqueous solution and L-ascorbic acid evenly at a mass ratio of 1:1;

[0038] (3) Transfer the above solution to a sealed container, and perform high-temperature reduction at 80 °C for 6 h to synthesize a three-dimensional cylindrical hydrogel (GH); wash the GH repeatedly with deionized water and tert-butanol, put the washed GH into liquid nitrogen to freeze it into a solid, and dry it in a freeze dryer at -99 °C for 48 h to obtain a three-dimensional black cylindrical GA aerogel, named GA-6;

[0039] (4) Under the condition that the Co 60 radioactive source intensity is 50 Gy / h, irradiate the above-prepared GA aerogel with gamma rays emitted by the Co 60 radioactive source for 5.5 kGy to obtain a three-dimensional graphene aerogel photothermal material, named RGA-6.

[0040] The aerogel materials before and after gamma-ray irradiation prepared in Example 2 were subjected to an interfacial water evaporation experiment under the illumination condition of simulated sunlight (1 sun). The specific experimental conditions were the same as those in steps (5) and (6) of Example 1. Using the experimental data obtained in steps (5) and (6), the water evaporation rates and energy conversion efficiencies of the aerogel materials GA-6 and RGA-6 were calculated respectively.

[0041] Figure 2 The water evaporation performance of the unirradiated GA-3 and GA-6 graphene aerogels prepared in Examples 1 and 2 of the present invention under the light intensity of 1 sun was found. The water evaporation rate of the unirradiated aerogel could reach 2.702 Kg / (m 2 ·h) and 1.199 Kg / (m 2 ·h), which was significantly higher than the evaporation rate of pure water (0.384 Kg / (m 2 ·h)). Figure 3 For the comparison chart of the water evaporation rates of the GA aerogel before and after irradiation by the gamma rays emitted from the Co 60 radioactive source under the light intensity of 1 sun, it can be seen from the figure that the water evaporation rate of the aerogel will be significantly increased after a certain irradiation. The evaporation rate of RGA-3 is as high as 4.80 Kg / (m 2 ·h), and the evaporation rate of RGA-6 is as high as 3.478 Kg / (m 2 ·h), indicating that after gamma-ray irradiation, the performance of the three-dimensional graphene aerogel can be changed, making its interaction with water stronger, and significantly improving the photothermal performance and water evaporation performance of the prepared three-dimensional graphene aerogel.

[0042] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a three-dimensional graphene aerogel photothermal material by gamma-ray irradiation, characterized in that, The method is as follows: uniformly mix an aqueous solution of graphene oxide with L-ascorbic acid, place it in a sealed container for a reduction reaction to form a wet hydrogel; wash the wet hydrogel and solidify it in liquid nitrogen, and obtain a three-dimensional graphene aerogel through low-temperature freeze-drying; irradiate the three-dimensional graphene aerogel with gamma rays to obtain a three-dimensional graphene aerogel photothermal material.

2. The method for preparing the three-dimensional graphene aerogel photothermal material by gamma-ray irradiation according to claim 1, wherein The concentration of the aqueous solution of graphene oxide is 2-6 mg / mL.

3. The method for preparing a three-dimensional graphene aerogel photothermal material by gamma-ray irradiation according to claim 1, characterized in that, The mass ratio of graphene oxide to L-ascorbic acid is 1:(1-10).

4. The method for preparing a three-dimensional graphene aerogel photothermal material by gamma-ray irradiation according to claim 1, characterized in that, Reduce at 80 °C for 6 h to form a wet hydrogel.

5. The method for preparing the three-dimensional graphene aerogel photothermal material by gamma-ray irradiation according to claim 1, wherein, The detergent used to wash the wet hydrogel is one or more of deionized water, ethanol, and tert-butanol.

6. The method for preparing the three-dimensional graphene aerogel photothermal material by gamma-ray irradiation according to claim 1, characterized in that, By Co 60 The three-dimensional graphene aerogel is irradiated by gamma rays emitted from a radiation source.

7. The method for preparing the three-dimensional graphene aerogel photothermal material by gamma-ray irradiation according to claim 6, characterized in that, Co 60 The irradiation intensity of the radiation source is 30 - 80 Gy / h.

8. The method for preparing a three-dimensional graphene aerogel photothermal material by gamma-ray irradiation according to claim 7, characterized in that, Three-dimensional graphene aerogel under Co 60 The radiation dose received under the irradiation of a radiation source is 1 to 10 kGy.

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