Preparation method of composite photothermal conversion material based on hot pasting waste powder

Abstract

The preparation method of the composite photo-thermal conversion material based on the hot paste waste powder comprises the following steps that supernate obtained after the hot paste waste powder and hydrochloric acid fully react is taken, a sodium hydroxide solution is added for a reaction, and a ferric hydroxide colloidal solution is obtained; dropwise adding the graphene oxide dispersion liquid into the ferric hydroxide colloidal solution to generate coagulation, and cleaning and drying the collected black precipitate; and calcining the black precipitate to obtain the composite photo-thermal conversion material based on the hot pasting waste powder. According to the preparation method of the composite photothermal conversion material, the hot paste waste powder which is wide in source and easy to obtain is used as the raw material to prepare the composite photothermal conversion material, and the composite photothermal conversion material has the advantages of being high in absorbance and photothermal conversion efficiency, low in cost, environmentally friendly and the like. The embodiment of the invention further provides the composite photo-thermal conversion material based on the hot pasting waste powder and a solar photo-thermal evaporation device.

Description

Technical Field

[0001] The present application belongs to the technical field of material recycling, and in particular, relates to a method for preparing a composite photothermal conversion material based on waste thermal paste powder. Background Art

[0002] In order to cope with the increasingly serious problem of fresh water shortage, the development of efficient, large-scale and sustainable seawater desalination technology has become a research focus. Although traditional seawater desalination technologies such as reverse osmosis and multi-stage flash distillation can achieve seawater desalination, they face limitations such as expensive and complex equipment, high operation and maintenance costs, and high traditional energy consumption.

[0003] In this context, solar-driven interfacial photothermal evaporation technology stands out. This technology converts solar energy into thermal energy with the help of photothermal conversion materials. Since thermal evaporation only occurs at the air-water interface, it can reduce conductive heat loss and improve solar-steam conversion efficiency. It is regarded as a promising technology for efficient fresh water acquisition.

[0004] However, how to maximize the use of solar energy is the key to the application of this technology. Enhancing the light collection ability of the light absorption layer (expanding the absorption range, reducing the transmittance / reflectivity) is an important method. Currently, research focuses on photothermal materials (precious metal nanoparticles, carbon-based materials, etc.). However, the preparation cost of these materials is high, the conditions are demanding, and the process is complicated. Summary of the invention

[0005] In response to the problems existing in the above-mentioned related technologies, the present application provides a composite photothermal conversion material based on waste thermal paste powder and a preparation method thereof, and a solar thermal evaporation device. The composite photothermal conversion material is prepared by using waste thermal paste powder, which is widely available and easily obtained, as raw material. The composite photothermal conversion material has the advantages of high absorbance and photothermal conversion efficiency, low cost and environmental friendliness.

[0006] In a first aspect, the present invention provides a method for preparing a composite photothermal conversion material based on waste thermal paste powder, comprising the following steps: The supernatant after the waste powder of hot stamping paste and hydrochloric acid fully react is taken, and sodium hydroxide solution is added to react to obtain a ferric hydroxide colloidal solution; Dropping the graphene oxide dispersion into the ferric hydroxide colloidal solution to cause coagulation, and washing and drying the collected black precipitate; and After the black precipitate is calcined, a composite light-to-heat conversion material based on thermal paste waste powder is obtained.

[0007] Furthermore, the supernatant obtained after the waste powder of the heat extraction post is fully reacted with hydrochloric acid is added with sodium hydroxide solution to react to obtain a ferric hydroxide colloidal solution, comprising: Take the supernatant after the waste powder of the hot post is fully reacted with hydrochloric acid; Add a sodium hydroxide solution to the supernatant, stir and keep introducing air to obtain the iron hydroxide colloid solution.

[0008] Further, the concentration of the hydrochloric acid is 20 wt%, the concentration of the sodium hydroxide solution is 20 wt%, and the duration of introducing air is 24 h.

[0009] Further, when the graphene oxide dispersion is dropped into the iron hydroxide colloid solution, coagulation occurs, and the collected black precipitate is washed and dried, including: Drop the graphene oxide dispersion into the iron hydroxide colloid solution to form a mixed solution; and The mixed solution is stratified, and the lower-layer black precipitate is centrifuged, washed multiple times with deionized water and absolute ethanol respectively, and then vacuum dried.

[0010] Further, the concentration of the graphene oxide dispersion is 0.5 mg / mL.

[0011] Further, after the black precipitate is calcined, a composite photothermal conversion material based on thermal paste waste powder is obtained, including: Under nitrogen protection, the black precipitate is calcined in a tube furnace to obtain the composite photothermal conversion material based on thermal paste waste powder.

[0012] In a second aspect, an embodiment of the present application further provides a composite photothermal conversion material based on thermal paste waste powder, and the composite photothermal conversion material is prepared by the method described in any one of the above.

[0013] In a third aspect, an embodiment of the present application further provides a solar photothermal evaporation device, including a photothermal conversion part and a water supply support part. The photothermal conversion part is arranged above the water supply support part, the water supply support part floats on the water surface, and the photothermal conversion part is prepared by placing the above-mentioned composite photothermal conversion material on a load medium.

[0014] Further, the load medium is recycled spunlace non-woven fabric. The composite photothermal conversion material is ultrasonically dispersed in deionized water, and the recycled spunlace non-woven fabric that has been cleaned and dried is immersed in the solution and dried to obtain the photothermal conversion part.

[0015] Further, the water supply support part is made of sodium alginate aerogel.

[0016] In the preparation method of the composite photothermal conversion material based on hot sticker waste powder provided by the embodiments of the present application, first, the hot sticker waste powder is fully reacted with hydrochloric acid, and the supernatant containing soluble substances such as iron salts is separated. Then, sodium hydroxide solution is slowly added to the supernatant for neutralization reaction. Iron ions combine with hydroxide ions to form iron hydroxide colloid. After that, the colloid solution can be purified or concentrated to improve its stability and purity. Then, the graphene oxide dispersion is slowly dropped into the iron hydroxide colloid solution, and coagulation occurs due to the electrostatic interaction and van der Waals force between the two, forming a black precipitate. Then, the precipitate is collected and washed to remove unreacted raw materials and impurities. Then, the washed precipitate is dried to obtain a dried composite material precursor. Finally, the dried composite material precursor is calcined in a high-temperature furnace. The calcination temperature and time are adjusted according to specific material and performance requirements. During calcination, the iron hydroxide colloid is converted into inorganic substances such as iron oxide, and graphene oxide undergoes pyrolysis or graphitization and other changes to form a composite photothermal conversion material with excellent photothermal conversion performance. The preparation method of the composite photothermal conversion material based on hot sticker waste powder provided by the embodiments of the present application realizes the resource utilization of waste, reduces environmental pollution and contributes to energy conservation and emission reduction. The prepared composite photothermal conversion material has good performance and can meet the application requirements of different fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0018] Figure 1 It is a schematic flow chart of the preparation method of the composite photothermal conversion material provided by the embodiments of the present application; Figure 2 It is a schematic diagram of the actual preparation process of the composite photothermal conversion material provided by the embodiments of the present application; Figure 3 It is a schematic diagram of the physical object of the recovered hot sticker waste powder raw material used in the preparation method provided by the embodiments of the present application; Figure 4 It is a schematic diagram of the structure of the solar photothermal evaporation device provided by the embodiments of the present application; Figure 5 It is a schematic diagram of the electron microscope photo of the sodium alginate aerogel used in the solar photothermal evaporation device provided by the embodiments of the present application; Figure 6 For Figure 4 Schematic diagram of the mass change of the sodium alginate aerogel before and 1 minute after water absorption; Figure 7For Figure 4 Schematic diagram of the water supply capacity test of sodium alginate aerogel; Figure 8 Schematic diagram of the comparison of evaporation curves of the evaporation mass varying with time in the performance test of different loading media for photothermal conversion; Figure 9 For Figure 8 Schematic diagram of the comparison of the surface temperature changes of different loading media under sunlight; Figure 10 Schematic diagram of infrared thermal imaging in the performance test of the film obtained from the thermally pasted waste powder composite material prepared by the preparation method provided in the embodiment of the present application for photothermal conversion; Figure 11 Schematic diagram of the evaporation curve of the evaporation mass varying with time of the solar photothermal evaporation device formed by the thermally pasted waste powder composite photothermal conversion material prepared by the preparation method provided in the embodiment of the present application in a high-concentration (mass fraction of 10%) sodium chloride solution; Figure 12 Schematic diagram of the 24-hour evaporation rate change of the solar photothermal evaporation device formed by the thermally pasted waste powder composite photothermal conversion material prepared by the preparation method provided in the embodiment of the present application in a high-concentration (mass fraction of 10%) sodium chloride solution; Figure 13 When using the solar evaporation device provided in the embodiment of the present application for seawater desalination, the main ions (sodium ions (Na + ), magnesium ions (Mg 2+ ), potassium ions (K + ), calcium ions (Ca 2+ )) concentration change schematic diagram before and after simulation of seawater desalination; Figure 14 Schematic diagram of the evaporation rate change of the cyclic experiment of the solar photothermal evaporation device formed by the thermally pasted waste powder composite photothermal conversion material prepared by the preparation method provided in the embodiment of the present application; Figure 15 When using the solar evaporation device provided in the embodiment of the present application for seawater desalination, the absorbance change schematic diagram of the simulated mixed organic dye waste liquid (a mixture of 40 mg / L rhodamine B (RhB), methyl orange (MO) and methylene blue (MB)) before and after solar photothermal water evaporation; Figure 16 When using the solar evaporation device provided in the embodiment of the present application for seawater desalination, the absorbance change schematic diagram of the simulated heavy metal ion solution (a mixture of 1 g / L copper chloride, 0.8 g / L cobalt chloride and 0.5 g / L iron chloride) before and after solar photothermal water evaporation; Figure 17Schematic diagram of the change in absorbance over time after adding the composite material of thermally adhered waste powder provided by the embodiments of the present application to an MB solution (40 mg / L). Figure 18 Schematic diagram of the change in absorbance over time after adding the composite material of thermally adhered waste powder provided by the embodiments of the present application to a tetracycline (TCY) solution (40 mg / L).

[0019] The realization of the purpose, functional features, and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0021] It should be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0022] It should also be understood that the terms used in this specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this specification of the present application and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0023] Refer to Figures 1 to 2 The embodiments of the present application provide a preparation method of a composite photothermal conversion material based on thermally adhered waste powder, including the following steps: S101: Take the supernatant after the thermally adhered waste powder reacts fully with hydrochloric acid, add a sodium hydroxide solution for reaction to obtain a ferric hydroxide colloidal solution; S102: Drop the graphene oxide dispersion into the ferric hydroxide colloidal solution, causing coagulation, and wash and dry the collected black precipitate; and S103: After calcining the black precipitate, obtain a composite photothermal conversion material based on thermally adhered waste powder.

[0024] Specifically, in the preparation method of the composite photothermal conversion material based on hot-sticker waste powder provided by the embodiments of the present application, first, take the hot-sticker waste powder (refer to Figure 3 ), and react it fully with hydrochloric acid to separate the supernatant containing soluble substances such as iron salts. Then, slowly add sodium hydroxide solution to the supernatant for neutralization reaction. Iron ions combine with hydroxide ions to form iron hydroxide colloid. After that, the colloid solution can be purified or concentrated to improve its stability and purity. Then, slowly drop the graphene oxide dispersion into the iron hydroxide colloid solution, and use the electrostatic interaction and van der Waals force between the two to cause a coagulation phenomenon, forming a black precipitate. Then, collect the precipitate and wash it to remove unreacted raw materials and impurities. Then, dry the washed precipitate to obtain a dry composite material precursor. Finally, place the dry composite material precursor in a high-temperature furnace for calcination. The calcination temperature and time are adjusted according to specific material and performance requirements. During calcination, the iron hydroxide colloid is converted into inorganic substances such as iron oxide, and the graphene oxide undergoes pyrolysis or graphitization and other changes, forming a composite photothermal conversion material (Fe3O4 / RGO powder, FRP) with excellent photothermal conversion performance. The preparation method of the composite photothermal conversion material based on hot-sticker waste powder provided by the embodiments of the present application realizes the resource utilization of waste, reduces environmental pollution and helps energy conservation and emission reduction. The prepared composite photothermal conversion material has good performance and can meet the application requirements of different fields.

[0025] It should be noted that Fe3O4 has the characteristics of high theoretical specific capacity, low cost and environmental friendliness, and its band gap is also relatively narrow (0.1 eV). Therefore, it can achieve full solar spectrum absorption, and can be excited by sunlight to cause electronic transitions, generating photoinduced carriers and thus having stable photocatalytic performance. RGO has high-efficiency light absorption and photothermal conversion performance, controllable interface design, environmental adaptability and low cost, and has become an ideal material in the field of solar-driven water evaporation.

[0026] Furthermore, in some embodiments of the present application, the supernatant obtained by fully reacting the hot-sticker waste powder with hydrochloric acid is added with sodium hydroxide solution for reaction to obtain an iron hydroxide colloid solution, including: Take the supernatant obtained by fully reacting the hot-sticker waste powder with hydrochloric acid; Add sodium hydroxide solution to the supernatant, stir and keep introducing air to obtain the iron hydroxide colloid solution.

[0027] Specifically, the iron oxide in the hot-sticker waste powder reacts with hydrochloric acid to form soluble iron salts. Adding sodium hydroxide solution to the supernatant (containing iron salts) after the reaction undergoes a double decomposition reaction to form iron hydroxide precipitate. Under the condition of stirring and introducing air, part of the iron hydroxide precipitate aggregates to form colloid particles, and then an iron hydroxide colloid solution is obtained, providing a new direction for the resource utilization of hot-sticker waste powder.

[0028] Further, in some embodiments of the present application, the concentration of hydrochloric acid is 20 wt%, the concentration of sodium hydroxide solution is 20 wt%, and the duration of air introduction is 24 h.

[0029] For example, referring to Figure 2 , in an embodiment of the present application, a preparation method of a composite photothermal conversion material based on waste powder of thermal stickers includes the following steps: Weigh the recycled waste powder of thermal stickers (WP, 5 g) as shown in Figure 3 , mix it with hydrochloric acid (HCl) solution (concentration 20 wt%, 100 mL used), after the two react fully, centrifuge, take the supernatant, add excessive NaOH solution (20 wt%) to it and perform magnetic stirring, then, introduce air into it and keep the ventilation for 24 h; Dropwise add an aqueous solution of GO (graphene oxide) (concentration 0.5 mg / mL, 400 mL used) into the mixed solution, and let it stand for 24 h. The mixed solution is stratified. Take the lower black precipitate for centrifugation, and wash it five times with deionized water and anhydrous ethanol respectively, then perform vacuum drying (dry at 65 °C for 10 h); Heat the dried sample in a tubular furnace. The heating conditions are: nitrogen as the protective gas, heat at 500 °C for 2 h. Grind the heated sample to obtain a composite material based on waste powder of thermal stickers.

[0030] In the embodiments of the present application, it is specified that the concentration of hydrochloric acid is 20 wt%, the concentration of sodium hydroxide solution is 20 wt%, and the duration of air introduction is 24 h. These parameters are determined comprehensively based on a large number of experimental studies and theoretical analyses, aiming to ensure that the iron element in the waste powder of thermal stickers can be efficiently and stably converted into iron hydroxide colloid, while ensuring the safety and repeatability of the operation.

[0031] Further, in some embodiments of the present application, when the graphene oxide dispersion is dropped into the iron hydroxide colloid solution, coagulation occurs, and the collected black precipitate is washed and dried, including: Dropwise add the graphene oxide dispersion into the iron hydroxide colloid solution to form a mixed solution; and The mixed solution is stratified. Take the lower black precipitate for centrifugation, and wash it multiple times with deionized water and anhydrous ethanol respectively, then perform vacuum drying.

[0032] That is, first, the graphene oxide dispersion is slowly and evenly dropped into the iron hydroxide colloid solution and continuously stirred to form a stable mixture, preparing for the coagulation reaction. Then, after the mixture is left standing, coagulation and stratification occur. The black precipitate at the lower layer is the preliminary composite product but contains impurities. Next, the precipitate is processed: one is centrifugation, using centrifugal force to separate the precipitate from the supernatant to obtain a relatively pure precipitate; the second is washing, washing multiple times with deionized water and absolute ethanol to remove residual ions, soluble impurities, moisture, and organic impurities respectively; the third is drying, adopting vacuum drying to evaporate the moisture at a low temperature to avoid high-temperature oxidation and decomposition of the material, obtaining a dry and pure composite material precursor. Through this series of precipitation treatments, impurities can be effectively removed, the purity and quality of the material can be improved, laying a foundation for obtaining high-performance composite photothermal conversion materials subsequently.

[0033] Further, in some embodiments of the present application, the concentration of the graphene oxide dispersion is 0.5 mg / mL.

[0034] Specifically, in the preparation process of the graphene oxide - iron hydroxide colloid composite material, the concentration of the graphene oxide dispersion is one of the key factors affecting the performance of the composite material. In the present application, the concentration of the graphene oxide dispersion is set to 0.5 mg / mL based on a large number of experimental studies, theoretical analyses, and comprehensive considerations of the performance requirements of the composite material.

[0035] Further, in some embodiments of the present application, after the black precipitate is calcined, a composite photothermal conversion material based on heat paste waste powder is obtained, including: Under nitrogen protection, the black precipitate is calcined in a tubular furnace to obtain the composite photothermal conversion material based on heat paste waste powder.

[0036] Specifically, when preparing the composite photothermal conversion material based on heat paste waste powder, the calcination treatment of the black precipitate is crucial. The present application uses nitrogen protection and calcines in a tubular furnace, which has multiple advantages. The role of nitrogen protection is significant. On the one hand, it can isolate oxygen, prevent the active components in the black precipitate from being oxidized, and maintain the chemical composition and structure stability of the material; on the other hand, it can create a specific reaction atmosphere, regulate the chemical reactions during the calcination process, and optimize the material performance. The advantages of tubular furnace calcination are relatively prominent. Its precise temperature control system can ensure that the calcination is carried out at an appropriate temperature to obtain a material with ideal performance; the uniform and stable atmosphere is conducive to the uniformity of the material performance; the operation is convenient and safe, with a high degree of automation, which can reduce human errors and improve the experimental repeatability.

[0037] In addition, an embodiment of the present application further provides a composite photothermal conversion material based on hot-pasted waste powder, and the composite photothermal conversion material is prepared by the method described in any one of the above. For the specific preparation method of the composite photothermal conversion material, refer to the above embodiments. Since the specific preparation method of the composite photothermal conversion material adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated herein one by one.

[0038] In the third aspect, referring to Figure 4 , an embodiment of the present application further provides a solar photothermal evaporation device, including a photothermal conversion part 3 and a water supply and support part 2. The photothermal conversion part 3 is arranged above the water supply and support part 2, and the water supply and support part 2 floats on the water surface of the simulated seawater 1. The photothermal conversion part 3 is prepared by placing the composite photothermal conversion material described above on a load medium.

[0039] Specifically, as Figure 4 shown, the solar photothermal evaporation device further provided by an embodiment of the present application is composed of a photothermal conversion part 3 and a water supply and support part 2. The photothermal conversion part 3 is arranged above the water supply and support part 2 and is made by placing the composite photothermal conversion material described above on a load medium. Under the irradiation of the simulated solar light source 5, the photothermal conversion part 3 efficiently absorbs the light of the solar light source 5 and converts it into heat energy, so that the water transported by the water supply and support part 2 volatilizes into water vapor 4, and the water vapor 4 can efficiently condense into fresh water, thereby realizing the desalination of seawater. The composite photothermal conversion material provided by an embodiment of the present application has a wide-spectrum absorption characteristic and can efficiently convert solar energy into heat energy. The load medium plays a role of supporting and fixing to ensure the stability of the material. The water supply and support part 2 floats on the water surface of the simulated seawater 1, provides a stable water source and heat insulation for the photothermal conversion part 3, prevents downward heat conduction on the surface of the photothermal conversion part 3, and causes heat loss, so it has high-efficiency photothermal conversion ability, and at the same time has high evaporation performance and good stability.

[0040] Furthermore, in some embodiments of the present application, the load medium is recycled spunlace non-woven fabric. The composite photothermal conversion material is ultrasonically dispersed in deionized water, and the recycled and washed and dried spunlace non-woven fabric is immersed in the solution and dried to obtain the photothermal conversion part.

[0041] For example, the prepared hot-pasted waste powder composite photothermal conversion material (300 mg of FRP composite material) is ultrasonically dispersed in deionized water (100 mL). The recycled and washed and dried facial tissue (spunlace non-woven fabric, SN), with the size of SN being 3 cm × 3 cm, is immersed in the mixed solution for 30 min, and then dried (dried at 65 °C for 6 h). After repeating the above process three times, the Fe3O4 / RGO@SN film (denoted as FRP@SN) is obtained.

[0042] Further, in some embodiments of the present application, the water supply support part is made of sodium alginate aerogel.

[0043] For example, SA (500 mg) and CaCO3 (500 mg) are added to deionized water (30 mL), and magnetic stirring is carried out for 1 h to make them evenly mixed. Then, glucono-delta-lactone (800 mg) is mixed therein, and it is left standing for 5 min. Subsequently, it is vertically frozen for 12 h. The gel is placed in a freeze dryer for freeze drying for 48 h to obtain sodium alginate aerogel or SA aerogel.

[0044] Refer to Figure 5 , the electron microscope photograph of SA aerogel shows that the aerogel has abundant pores and cells with sizes between micrometers and sub-micrometers. Its three-dimensional porous structure can easily filter impurities in seawater, ensure that water can be continuously transported to the evaporation device, and promote salt ion exchange, thereby preventing the accumulation of salts contained in seawater in the support layer. Water is transported to the photothermal evaporation layer through the interconnected and continuous pores inside SA. Refer to Figure 6 , the water absorption performance of SA aerogel was tested, and the aerogel can absorb 8.25 g of water within 1 minute. Refer to Figure 7 , the strong capillary action ensures that SA has good water transportation ability. As Figure 6 shown, methyl orange placed on the surface of SA aerogel quickly dissolves and enters the bottom liquid. After 2 minutes, the water body below starts to turn yellow, and the color gradually deepens with the increase of time, which fully demonstrates the excellent water supply and ion exchange ability of the aerogel. For the heat-insulating water supply layer, in addition to ensuring sufficient water supply, heat loss should be reduced as much as possible. The thermal conductivity of SA is 0.025 W / m·K, which is lower than that of polyethylene foam (0.035 - 0.038 W / m·K) and significantly lower than that of water (0.59 W / m·K). The FRP@SN membrane, as the light absorption layer, can achieve continuous water supply and effective salt ion exchange during the evaporation process, and maintain continuous and stable local heating, thereby achieving a high evaporation rate.

[0045] The FRP@SN thin film is placed on the SA aerogel acting as a water supplier. At the same time, the SA aerogel, as a heat-insulating layer, can effectively inhibit the heat loss of the heat conducted from the FRP@SN absorption layer to the large amount of water below, and the two are combined and assembled into a photothermal evaporation device part.

[0046] For example, in an embodiment of the present application, a solar simulator with an AM 1.5G filter is used as the only light source for solar photothermal evaporation testing. Meanwhile, during the test, a computer-controlled electronic balance (with a precision of 0.001 g) is used to measure and record the mass change during the evaporation process every 10 s. The temperature change on the surface of the sample is monitored and recorded by a thermal infrared imager and a thermocouple. The light intensity is adjusted by a light power meter so that the light intensity incident on the surface of the SN thin film based on the thermally adhered waste powder composite photothermal conversion material is one solar (1 kW / m 2 ), and the irradiation duration is 40 min. Meanwhile, the mass change of water evaporation in the evaporation system is recorded, as Figure 8 shown. Figure 8 are the evaporation curves of the mass of water over time in the performance test of photothermal conversion for pure water, blank SN thin film, untreated thermally adhered waste powder thin film WP@SN, and the thin film FRP@SN loaded with the photothermal conversion material prepared in the embodiment of the present application. Through the slopes of the different curves in the figure, it can be calculated that the evaporation device based on FRP@SN has the largest water evaporation amount per unit area, and its water evaporation rate is 1.49 kg / m 2 ·h, which is 6.2 times the evaporation rate of pure water (pure water means there is no substance on the water surface of the container). The evaporation rates of the blank SN thin film and the untreated thermally adhered waste powder thin film WP@SN are 0.57 kg / m 2 ·h and 0.92 kg / m 2 ·h respectively. This is mainly because the thin film loaded with the thermally adhered waste powder composite material as the photothermal layer has excellent light absorption, photothermal conversion, and thermal localization effects, improving the photothermal conversion efficiency. Moreover, the sodium alginate aerogel achieves good heat insulation and sufficient water supply. Referring to Figure 9 , a schematic diagram showing the comparison of the surface temperature changes of the photothermal devices FRP@SN, WP@SN, and blank SN over time measured by a K-type thermocouple is shown. It can be seen from Figure 9 that after being irradiated by sunlight, the evaporation surface temperature of FRP@SN rises most rapidly and tends to be stable after 1200 s. Referring to Figure 10 , the test results of the thermal infrared imager further confirm this conclusion. When irradiated for the same time, the surface temperature of FRP@SN is constantly 31.2 °C, which is higher than the steady-state temperature of the surfaces of other solar absorbers, indicating that FRP@SN has a faster thermal response speed.

[0047] Referring to Figure 11 , in a high-concentration sodium chloride solution (mass fraction of 10%), the evaporation system is continuously evaporated for 24 h, and the evaporation rate also remains stable, with an average evaporation rate reaching 1.43 kg / m 2 ·h ( Figure 12). No salt crystallization appeared on the surface of the evaporation device, thus ensuring that the evaporation rate was not affected.

[0048] Place the solar thermo-photovoltaic evaporation device provided in the embodiment of the present application on the water surface filled with real seawater. Use a solar simulator with an AM 1.5G filter as the only light source, which is incident on the surface of the film loaded with the composite thermo-photovoltaic conversion material of waste toner powder. Use a glass cover to collect the purified water vapor. Test the concentrations of Na + , Mg 2+ , K + and Ca 2+ ions in the real seawater and the desalinated solution by inductively coupled plasma optical emission spectrometer to determine the seawater desalination effect of the evaporation device. Refer to Figure 13 , the ion concentrations (Na + , Mg 2+ , K + and Ca 2+ ) in the desalinated water decreased significantly from 24970, 1491, 801 and 450.3 ppm to 13.79, 1.892, 1.486 and 2.334 ppm. The ion concentration in the desalinated water is much lower than the drinking water standard formulated by the World Health Organization (WHO). This indicates that the evaporation device based on the waste toner powder thermo-photovoltaic conversion material can effectively remove Na + , Mg 2+ , K + and Ca 2+ ions in seawater, and the practical application of producing fresh water can be realized through the ion rejection property of the evaporation device based on the waste toner powder thermo-photovoltaic conversion material.

[0049] Place the solar thermo-photovoltaic evaporation device provided in the embodiment of the present application on the water surface filled with a sodium chloride solution with a concentration of 3.5 wt%. Use a solar simulator with an AM 1.5G filter as the only light source. Adjust the light intensity through a power meter so that the light intensity incident on the surface of the SN film loaded with the composite thermo-photovoltaic conversion material of waste toner powder is one solar energy (1 kW / m 2 ), and the irradiation duration is 40 min. At the same time, record the mass change of the water evaporation in the evaporation system. Refer to Figure 14 , which shows the change graph of the evaporation rate of a single evaporation device tested 20 times. The evaporation rate of the evaporation device does not decrease significantly and always maintains a stable evaporation rate, fully demonstrating its photo-thermal stability, reusability and durability.

[0050] Place the solar thermal evaporation device provided in the embodiment of the present application on the liquid surface containing the simulated mixed organic dye waste liquid and the simulated heavy metal ion solution. Use a solar simulator with an AM 1.5G filter as the only light source, which is incident on the surface of the film loaded with the composite photothermal conversion material based on thermal paste waste powder. Use a glass cover to collect the purified water vapor. Figure 15 and Figure 16 are respectively the schematic absorption spectra of the mixed organic dye (a mixture of 40 mg / L RhB, MO, and MB) and heavy metal ions (a mixture of 1 g / L copper chloride, 0.8 g / L cobalt chloride, and 0.5 g / L iron chloride) solutions before and after purification. After evaporation, the two simulated sewage waters hardly show any characteristic absorption peaks in the ultraviolet and visible light regions, which confirms that the photothermal evaporation device based on the composite material of thermal paste waste powder can effectively remove pollutants in the sewage.

[0051] In addition, add the composite material based on thermal paste waste powder prepared in the embodiment of the present application to the prepared MB (40 mg / L) solution, and place it in a dark room for 30 min to achieve the adsorption-desorption equilibrium between the catalyst surface and the dye molecules. Then, use a solar simulator with an AM1.5G filter as the only light source, and adjust the light intensity through a power meter so that the light intensity incident on the solution surface is one solar energy (1 kW / m 2 ) to test the photocatalytic degradation ability under different light illumination times. Take a 5 mL sample every 30 min, and use a photometer to perform the absorption spectrum test. The maximum ultraviolet absorption wavelength of MB is 665 nm. Take the residual liquid every half hour and measure its light absorbance using a spectrophotometer. Judge the change in the solution concentration by the change in the absorbance at the maximum absorption wavelength in the ultraviolet-visible diffuse reflection spectrum. Figure 17 shows the change in the light absorbance of the MB solution with time. As the light illumination time increases, the absorbance and concentration value of MB in the water body gradually decrease, indicating that the photothermal conversion composite material based on thermal paste waste powder has the ability to photocatalytically degrade MB organic dye.

[0052] Add the composite material based on thermal paste waste powder prepared in the embodiment of the present application to the prepared TCY (40 mg / L) solution, and place it in a dark room for 30 min to achieve the adsorption-desorption equilibrium between the catalyst surface and the dye molecules. Then, use a solar simulator with an AM 1.5G filter as the only light source, and adjust the light intensity through a power meter so that the light intensity incident on the solution surface is one solar energy (1 kW / m 2), the photocatalytic degradation ability under different light illumination times was tested. 5 mL of samples were taken every 30 min, and the absorption spectrum was measured using a photometer. The absorption wavelength of TCY was 350 nm. The residual liquid was taken every half hour, and its light absorbance was measured using a spectrophotometer. The change in the solution concentration was judged by the change in the absorbance at the absorption wavelength of 350 nm. Figure 18 It shows the change of the light absorbance of the surface TCY solution with time. As the light illumination time increases, the absorbance and concentration value of TCY in the water body gradually decrease, indicating that the composite material based on thermal paste waste powder has the ability to photocatalytically degrade the antibiotic TCY.

[0053] The above test results show that the composite material based on thermal paste waste powder prepared in the embodiments of the present application has the advantages of wide source, low cost, environmental friendliness and green environmental protection, etc., as well as excellent photothermal conversion effect and photothermal conversion efficiency. At the same time, the prepared solar photothermal evaporation device has a good evaporation rate and stability.

[0054] In summary, the solar photothermal evaporation device formed by the composite material based on thermal paste waste powder prepared in the embodiments of the present application has excellent photothermal conversion and evaporation characteristics. Through waste utilization and a simple preparation process, a photothermal material with high absorbance and a photothermal evaporation device with a high evaporation rate are realized, and thus can be effectively applied to the fields of solar seawater desalination, wastewater purification and photocatalytic degradation of sewage, and is suitable for popularization and application.

[0055] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A preparation method of a composite photothermal conversion material based on hot post waste powder, characterized in that, It includes the following steps: Take the supernatant after the hot post waste powder reacts fully with hydrochloric acid, add sodium hydroxide solution for reaction to obtain a ferric hydroxide colloid solution; Drop the graphene oxide dispersion into the ferric hydroxide colloid solution, causing coagulation, and wash and dry the collected black precipitate; and After the black precipitate is calcined, a composite photothermal conversion material based on the hot post waste powder is obtained.

2. The method according to claim 1, wherein The step of taking the supernatant after the hot post waste powder reacts fully with hydrochloric acid, adding sodium hydroxide solution for reaction to obtain a ferric hydroxide colloid solution includes: Take the supernatant after the hot post waste powder reacts fully with hydrochloric acid; Add sodium hydroxide solution to the supernatant, stir and keep introducing air to obtain the ferric hydroxide colloid solution.

3. The method according to claim 2, wherein The concentration of the hydrochloric acid is 20 wt%, the concentration of the sodium hydroxide solution is 20 wt%, and the duration of introducing air is 24 h.

4. The method according to claim 1, characterized in that, The step of dropping the graphene oxide dispersion into the ferric hydroxide colloid solution, causing coagulation, and washing and drying the collected black precipitate includes: Drop the graphene oxide dispersion into the ferric hydroxide colloid solution to form a mixture; and When the mixture is stratified, take the lower black precipitate for centrifugation, wash it multiple times with deionized water and absolute ethanol respectively, and then perform vacuum drying.

5. The method according to claim 4, wherein The concentration of the graphene oxide dispersion is 0.5 mg / mL.

6. The method according to claim 1, wherein The step that after the black precipitate is calcined, a composite photothermal conversion material based on the hot post waste powder is obtained includes: Under nitrogen protection, the black precipitate is calcined in a tubular furnace to obtain the composite photothermal conversion material based on the hot post waste powder.

7. A composite photothermal conversion material based on hot post waste powder, characterized in that, The composite photothermal conversion material is prepared by the method according to any one of claims 1 to 6.

8. A solar photothermal evaporation device, characterized in that, It includes a photothermal conversion part and a water supply support part. The photothermal conversion part is arranged above the water supply support part. The water supply support part floats on the water surface. The photothermal conversion part is prepared by placing the composite photothermal conversion material according to claim 7 on a load medium.

9. The solar thermal evaporation device according to claim 8, wherein, The load medium is recycled spunlace non-woven fabric. The composite photothermal conversion material is ultrasonically dispersed in deionized water. The recycled, washed and dried spunlace non-woven fabric is immersed in the solution and then dried to obtain the photothermal conversion part.

10. The solar thermal evaporation device according to claim 8, wherein, The water supply support part is made of sodium alginate aerogel.

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