Photo-thermal conversion film and preparation method and application thereof
阅读说明：本技术 一种光热转换膜及其制备方法和应用 (Photo-thermal conversion film and preparation method and application thereof ) 是由 韩凯 李双福 谢莹 毛停停 于 2021-08-27 设计创作，主要内容包括：本发明公开了一种光热转换膜及其制备方法和应用。一种光热转换膜,包括：基底,所述基底为亲水膜；光热转换材料,所述光热转换材料设于所述基底表面,组分包括硅基合金粉末和多孔硅基粉末中的至少一种。本发明提出的光热转换膜,由于各组件材质的选择,能够具有成本低、环境友好以及高吸光率的优点。(The invention discloses a photo-thermal conversion film and a preparation method and application thereof. A photo-thermal conversion film comprising: a substrate, which is a hydrophilic film; the photothermal conversion material is arranged on the surface of the substrate, and the components of the photothermal conversion material comprise at least one of silicon-based alloy powder and porous silicon-based powder. The photo-thermal conversion film provided by the invention has the advantages of low cost, environmental friendliness and high light absorption rate due to the selection of the material of each component.)
1. A photothermal conversion film, comprising:
a substrate, which is a hydrophilic film;
the photothermal conversion material is arranged on the surface of the substrate, and the components of the photothermal conversion material comprise at least one of silicon-based alloy powder and porous silicon-based powder.
2. A photothermal conversion film according to claim 1, wherein said silicon-based alloy powder is at least one of an aluminum-silicon alloy powder and an iron-silicon alloy powder; preferably, the silicon content in the silicon-based alloy powder is 5-50 wt%; preferably, the particle size of the silicon-based alloy powder is 1-80 μm; preferably, the pore diameter of the porous silicon-based powder is 0.01-0.3 μm; preferably, the ratio of the pore structure volume to the mass of the porous silicon-based powder is 0.001-0.5 cm3/g。
3. A photothermal conversion film according to claim 2, wherein said porous silicon-based powder is prepared by: etching the silicon-based alloy powder by using an etching solution; preferably, the preparation method of the porous silicon-based powder further comprises drying and grinding the powder after etching to obtain a solid.
4. A photothermal conversion film according to claim 3, wherein said etching solution is an aqueous acid solution or an aqueous alkali solution; preferably, the solute of the acid aqueous solution is at least one of hydrochloric acid, nitric acid, sulfuric acid and oxalic acid; preferably, the solute of the aqueous alkali solution is at least one of sodium hydroxide and potassium hydroxide; preferably, the etching temperature is 30-80 ℃; preferably, the etching time is 0.5-8 h.
5. A photothermal conversion film according to any of claims 1 to 4, wherein said hydrophilic film is at least one of a glass fiber film, an organic nylon film, or a pure cotton tissue.
6. A method for preparing a photothermal conversion film according to any of claims 1 to 5, comprising preparing the silicon-based alloy powder into a slurry, coating the slurry on the surface of the substrate, and drying the slurry.
7. The method of claim 6, wherein the slurry further comprises a binder and a solvent; preferably, the binder is one of sodium carboxymethylcellulose and polyvinylidene fluoride; preferably, the solvent is one of water and N-methyl pyrrolidone; preferably, the binder accounts for 1-30 wt% of the mass of the slurry; preferably, the slurry is prepared by mixing the silicon-based alloy powder, a binder and a solvent.
8. The method of claim 6, wherein the coating is performed by at least one of suction filtration, blade coating, spray coating, and spin coating.
9. A photothermal converter comprising the photothermal conversion film according to any one of claims 1 to 5.
10. Use of the photothermal converter of claim 9 in water treatment.
Technical Field
The invention belongs to the technical field of photo-thermal conversion, and particularly relates to a photo-thermal conversion film and a preparation method and application thereof.
Background
In order to deal with the crisis of fresh water resources, a plurality of technologies such as remote water transfer, sewage and wastewater recycling, seawater desalination and the like are carried out. Due to the abundance of resources, seawater desalination technology is considered to be one of the most promising technologies. The sea water desalination technologies which are mature to be applied today mainly comprise multi-effect flash evaporation (MSF), low-temperature multi-effect distillation (MED), Vapor Compression (VC), trans-osmosis membrane (RO), electro-osmosis (ED) and the like, and the technologies can produce fresh water by about 3.48X 10 per year10m3. The mature seawater desalination technology consumes a large amount of fossil energy, and the greenhouse gas discharged to the atmosphere per year is more than 7.676 multiplied by 107t; meanwhile, the high-concentration salt water discharged from the seawater desalination plant can seriously threaten the survival of aquatic organisms. Therefore, the seawater desalination industry urgently needs cleaner and more environment-friendly energy.
Among all renewable energy sources, solar energy is considered the most promising option for meeting human energy needs. The solar photo-thermal conversion water treatment technology has the advantages of cleanness, high efficiency, wide water source treatment range and the like, and can cover high/low concentration saline water, various river/lake water and sewage, so the technology has attracted attention in recent years. The interface evaporation technology is that the light-heat conversion film is arranged on a gas-liquid interface, and thin water at the interface can be directly heated to generate steam, so that higher light-heat water evaporation efficiency can be obtained.
In order to obtain a higher water evaporation rate and effectively improve the working efficiency of the interface evaporation water treatment technology, a photothermal conversion film capable of realizing broadband and efficient light absorption in the solar spectrum range needs to be developed. In the related art, carbon-based materials, noble metal nano materials or organic polymers are often used as light absorption materials to prepare the photothermal conversion film. However, carbon-based materials have high thermal conductivity, which can result in excessive heat loss; the preparation process of the noble metal nano-structure material is complex and the cost is high; meanwhile, organic polymer light-absorbing materials such as polypyrrole and polydopamine are poor in stability and easy to decompose in the actual wastewater treatment process. Therefore, high-stability, low-cost semiconductor materials that can achieve broadband and highly efficient light absorption by non-radiative relaxation under illumination have been attracting attention.
The researchers developed a silicon-based wide-spectrum absorption photothermal conversion material and a preparation method thereof, which comprises the steps of firstly taking foamy copper as a substrate, generating mutually crossed CuO nanowires through in-situ oxidation, then using plasma chemical vapor deposition amorphous silicon to form a core-shell nanowire structure CuO @ a-Si, and then using catalysis and plasma chemical vapor deposition to enable the amorphous silicon to partially grow into silicon nanowires to obtain a nano hierarchical structure. The structure not only can effectively utilize the light trapping characteristic of the one-dimensional nanowire array to improve the light capturing capability, but also can generate alloy quantum dots to be embedded on the interconnected core-shell nanowire main bodies in the high-temperature reduction process, and the absorption capability of the shell layer materials such as Si/Ge and the like to sunlight is enhanced through the local surface plasmon effect of metal. Finally, the material can obtain the light absorption rate of 93.5% within the range of 200-2500 nm. Although the material can realize broadband and efficient light absorption, the large-scale preparation and popularization and application of the material are limited by a complicated preparation process and a high-cost chemical vapor deposition method.
In summary, there is still a need to develop a photo-thermal conversion film that is easy to prepare, low in cost and environmentally friendly, and has high light absorption rate and high evaporation efficiency of hot water.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the invention provides a photo-thermal conversion film, which has the advantages of low cost, environmental friendliness and high light absorption rate due to the selection of the material of each component.
The invention also provides a preparation method of the photo-thermal conversion film.
The invention also provides a photo-thermal converter with the photo-thermal conversion film.
The invention also provides an application of the photo-thermal converter in water treatment.
According to an aspect of the present invention, there is provided a photo-thermal conversion film including:
a substrate, which is a hydrophilic film;
the photothermal conversion material is arranged on the surface of the substrate, and the components of the photothermal conversion material comprise at least one of silicon-based alloy powder and porous silicon-based powder.
According to a preferred embodiment of the present invention, at least the following advantages are provided:
(1) the photothermal conversion film takes at least one of silicon-based alloy powder and porous silicon-based powder as a light absorption material, and compared with a noble metal light absorption material, the photothermal conversion film has low raw material cost.
(2) Although the polycrystalline silicon based on photoelectric conversion and the black silicon material developed on the basis are already applied in the field of solar cells, the form is only limited in silicon wafers, and the preparation cost is high; the invention adopts the powdery light absorption material, and makes up the blank of the field of high-absorbance silicon powder material; in addition, compared with a silicon wafer, the preparation of the powder material is simpler, the cost is lower, and the existing forms are richer, so that the application of the silicon-based alloy material in the fields of photoelectricity, photo-thermal and the like can be greatly expanded.
(3) The introduction of the silicon element can improve the corrosion resistance and the wear resistance of the obtained photo-thermal conversion film, and can also enhance the stability of the material when the photo-thermal conversion film is applied to sewage treatment.
(4) In the silicon-based alloy powder, the metal and the crystal lattice of silicon interact, or the metal enters the crystal lattice of the silicon in a doped form to form a silicon-based alloy material; when the silicon-based alloy powder is illuminated, the surface of the silicon-based alloy powder can simultaneously generate a plasmon effect and a non-radiative relaxation domain effect, and the plasmon effect and the non-radiative relaxation domain effect can realize and improve the absorption of light by the cooperation of the plasmon effect and the non-radiative relaxation domain effect.
(5) In the using process of the silicon-based alloy powder, silicon elements on the surface of the silicon-based alloy powder can be oxidized to form a silicon dioxide protective layer, and the existence of the protective layer can effectively block a heat source to form local heat, so that the photo-thermal water evaporation rate and the actual water evaporation efficiency are improved.
(6) The pore structure in the porous silicon-based powder can effectively enhance the refraction and reflection of light in the porous silicon-based powder; on the surface of the substrate, the porous silicon-based powder is stacked, and a plurality of irregular pores formed among powder particles can further enhance the refraction and reflection of light in the photo-thermal conversion film, so that the photo-thermal conversion efficiency is improved; the hole structure and the irregular holes have synergistic effect with the plasmon effect and the nonradiative relaxation domain effect, so that the light absorption capacity of the photo-thermal conversion film can be further improved.
(7) The photothermal conversion film provided by the invention can obtain light absorption capacity as high as 93-97% within the range of 300-2500 nm, and is superior to the existing commercial materials.
In some embodiments of the present invention, the silicon-based alloy powder is at least one of an aluminum-silicon alloy powder and an iron-silicon alloy powder.
In some embodiments of the present invention, the silicon content in the silicon-based alloy powder is 5 to 50 wt%.
In some preferred embodiments of the present invention, the silicon content in the silicon-based alloy powder is 5 to 40 wt%.
In some preferred embodiments of the present invention, the silicon content in the silicon-based alloy powder is 5 to 20 wt%.
In some embodiments of the present invention, the silicon-based alloy powder has a particle size of 1 to 80 μm.
In some preferred embodiments of the present invention, the silicon-based alloy powder has a particle size of 1 to 40 μm.
In some preferred embodiments of the present invention, the silicon-based alloy powder has a particle size of 2 to 10 μm.
In some embodiments of the present invention, the silicon-based alloy powder has a thermal conductivity of 0.1 to 0.3W/m.K.
In some embodiments of the present invention, the porous silicon-based powder has a thermal conductivity of 0.01 to 0.08W/m.K.
In some embodiments of the present invention, the pore size of the pore structure on the porous silicon-based powder is 0.01 to 0.3 μm.
In some embodiments of the invention, the ratio of the pore structure volume to the mass of the porous silicon-based powder is 0.001 to 0.5cm3/g。
In some embodiments of the present invention, the porous silicon-based powder is prepared by etching the silicon-based alloy powder with an etching solution.
In some embodiments of the invention, the etching solution is an aqueous acid solution or an aqueous alkali solution.
In some embodiments of the invention, the solute of the aqueous acid solution is at least one of hydrochloric acid, nitric acid, sulfuric acid, and oxalic acid.
In some embodiments of the invention, the solute of the aqueous base solution is at least one of sodium hydroxide and potassium hydroxide.
In some embodiments of the invention, the etching temperature is 30-80 ℃.
In some embodiments of the invention, the temperature of the etching is achieved by preheating the etching solution.
In some embodiments of the invention, the etching time is 0.5-8 h.
In some embodiments of the present invention, the method for preparing the porous silicon-based powder further comprises drying and grinding the powder after the etching to obtain a solid.
And the etching can remove part of metal in the silicon-based alloy powder in a reaction mode to form the pore structure.
In addition, the pore structure is formed by removing part of metal in the silicon-based alloy powder, and the metal is a good thermal conductor, so that compared with the silicon-based alloy powder, the heat conduction performance of the porous silicon-based powder is further reduced, and the loss of heat in the photo-thermal conversion process is favorably reduced.
In some embodiments of the invention, the hydrophilic membrane is at least one of a fiberglass membrane, an organic nylon membrane, or a pure cotton tissue.
According to another aspect of the present invention, a method for manufacturing the photo-thermal conversion film is provided, which includes preparing the silicon-based alloy powder into a slurry, coating the slurry on the surface of the substrate, and drying the substrate.
The preparation method according to a preferred embodiment of the present invention has at least the following advantageous effects:
the preparation method provided by the invention is simple and easy to operate, low in energy consumption and easy for large-scale preparation.
In some embodiments of the invention, the slurry further comprises a binder and a solvent.
In some embodiments of the invention, the binder is one of sodium carboxymethylcellulose and polyvinylidene fluoride.
In some embodiments of the invention, the binder comprises 1 to 30 wt% of the mass of the slurry.
The adhesive can enable the silicon-based alloy powder to be tightly adhered to the surface of the substrate, so that the mechanical stability of the photo-thermal conversion film is improved;
in addition, the adhesive can also reduce the distribution spacing among the silicon-based alloy powder particles, so that irregular pores are generated on the surface of the light-heat conversion film, the absorption of light can be enhanced, and the silicon-based alloy powder can be used as a liquid water transmission and water vapor dissipation channel in the solar interface evaporation process to timely discharge generated water vapor.
In some embodiments of the invention, the solvent is one of water and N-methylpyrrolidone.
In some embodiments of the present invention, the slurry is prepared by mixing the silicon-based alloy powder, a binder, and a solvent.
In some embodiments of the invention, the method of coating is at least one of suction filtration, knife coating, spray coating, and spin coating.
According to still another aspect of the present invention, there is provided a photothermal converter comprising the photothermal conversion film.
In some embodiments of the present invention, the structure of the photothermal converter comprises:
a photo-thermal conversion film;
one end of the water transportation channel is connected with the photo-thermal conversion film, and the other end of the water transportation channel is immersed in the water body to be treated;
the heat insulation layer is positioned between the upper liquid level of the water body to be treated and the photo-thermal conversion film, and a through hole is formed in the heat insulation layer;
the water transport passage passes through the through-hole.
In some embodiments of the invention, the water transport channel is made of cotton.
In some embodiments of the present invention, the material of the thermal insulation layer is foam.
In some embodiments of the invention, the insulating layer is not in contact with the photothermal conversion film; the purpose is to increase the thermal insulation performance.
In some embodiments of the invention, the geometric center of the photo-thermal conversion film is within a contact range of the photo-thermal conversion film and the water transport channel.
The photo-thermal converter provided by the invention utilizes a local heating principle, reduces the direct contact between a water body to be treated and the photo-thermal conversion film (light absorption layer), and can effectively reduce heat loss and realize more efficient photo-thermal conversion water evaporation efficiency compared with the traditional integral heating mode;
the photothermal converter can be applied to the field of solar photothermal conversion water treatment, including the field of heavy metal ion wastewater, organic dye wastewater and antibiotic-containing medical wastewater treatment, and has extremely high impurity removal rate and great application prospect.
According to yet another aspect of the present invention, there is provided a use of the photothermal converter in water treatment.
In some embodiments of the invention, the application in water treatment comprises application in interface evaporation water treatment.
In some embodiments of the invention, the application in water treatment includes at least one of seawater, industrial wastewater, domestic wastewater and medical wastewater.
In some embodiments of the present invention, the application in water treatment includes at least one of heavy metal ion wastewater, organic dye wastewater and antibiotic-containing medical wastewater.
In some embodiments of the invention, the application in water treatment comprises irradiating the photothermal converter with a light source.
Drawings
The invention is further described with reference to the following figures and examples, in which:
FIG. 1 is a schematic view of photothermal converters obtained in examples 11 to 20 of the present invention and comparative examples 3 to 4;
FIG. 2 is an SEM image of silicon-based alloy powders obtained in examples 1-3 of the present invention;
FIG. 3 is a graph showing the thermal conductivity of silicon-based alloy powder used for the photothermal conversion films prepared in examples 1 to 3;
FIG. 4 is an absorption spectrum of the photothermal conversion films prepared in examples 1 to 4 and comparative example 1 in a wet state;
FIG. 5 is a graph showing the photothermal conversion films in the photothermal converters of examples 11 to 13 at 1 solar intensity of 1kW/m2Illuminating the temperature change curve of the surface;
FIG. 6 shows the photothermal converters of examples 11 to 13 at 1kW/m2Water body weight loss change curves of pure water when the water is used for solar interface evaporation water treatment under illumination and a control group;
FIG. 7 shows the photothermal converters prepared in examples 14 to 20 and comparative examples 3 to 4 at 1kW/m2A water body weight loss change curve when the water body is used for solar interface evaporation water treatment under illumination;
FIG. 8 shows photothermal converters prepared in examples 11-13 at 1kW/m2A purification performance diagram of the wastewater containing heavy metal ions when the wastewater is used for solar interface evaporation water treatment under illumination;
FIG. 9 shows photothermal converters prepared in examples 11-13 at 1kW/m2A graph of the purification performance of organic dye wastewater containing methylene blue or methyl orange when used in solar interface evaporation water treatment under illumination.
Reference numerals: 1. a photo-thermal conversion film; 2. a heat insulating layer; 3. a water transfer channel; 4. water to be treated; 5. a light source.
Detailed Description
The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.
Examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
Example 1
In this embodiment, a photothermal conversion film is prepared, and the specific process is as follows:
A1. 200mg of an aluminum-silicon alloy powder having a silicon content of 10 wt% and a particle size of 5 μm (silicon-based alloy powder, noted as 5 μm AlSi)10) 10.5mg of polyvinylidene fluoride is added into 20mL of N-methyl pyrrolidone, and the mixture is stirred for 12 hours at room temperature to prepare slurry;
A2. and loading the slurry on the surface of the glass fiber membrane in a vacuum filtration mode, and drying in an oven to obtain the photothermal conversion membrane.
Example 2
In this embodiment, a photothermal conversion film is prepared, and the specific process is as follows:
B1. adding 1g of 5-micron aluminum-silicon alloy powder with the silicon content of 10 wt% into hydrochloric acid etching solution preheated to 60 ℃ for reaction for 2h, and then drying and grinding a solid product to obtain a porous silicon-based alloy material (hereinafter referred to as Si-HCl);
B2. adding 200mg of Si-HCl and 10.5mg of polyvinylidene fluoride into 20mL of N-methyl pyrrolidone, and stirring at room temperature for 12 hours to prepare slurry;
B3. and loading the slurry on the surface of the glass fiber membrane in a suction filtration mode, and drying in an oven to obtain the photothermal conversion membrane.
Example 3
This example prepares a photothermal conversion film, and the specific process is different from that of example 2:
in step B1, the hydrochloric acid etching solution is replaced by sodium hydroxide etching solution, and the obtained porous silicon-based powder is called Si-NaOH.
Example 4
This example prepares a photothermal conversion film, and the specific process is different from that of example 1:
in the step A1, the silicon-based alloy powder is ferrosilicon alloy powder with silicon content of 6.5 wt% and particle size of 2-4 μm (noted as FeSi with particle size of 2-4 μm)6.5) (ii) a The particle size of the powder particles is distributed within a certain range and is not a definite value.
Example 5
This example prepares a photothermal conversion film, and the specific process is different from that of example 1:
in step A1, the silicon-based alloy powder used is an aluminum-silicon alloy powder (noted as 5 μm AlSi) with a silicon content of 40 wt% and a particle size of 5 μm40)。
Example 6
This example prepares a photothermal conversion film, and the specific process is different from that of example 1:
in step A1, the silicon-based alloy powder used was an aluminum-silicon alloy powder (denoted as 74 μm AlSi) having a silicon content of 10 wt% and a particle size of 74 μm10)。
Example 7
This example prepares a photothermal conversion film, and the specific process is different from that of example 2:
in the step B1, the hydrochloric acid etching solution is replaced by the nitric acid etching solution, and the obtained porous silicon-based powder is called Si-HNO3。
Example 8
This example prepares a photothermal conversion film, and the specific process is different from that of example 2:
in step B1, replacing hydrochloric acid etching solution with oxalic acid etching solution to obtain porous silicon-based powder called Si-H2C2O4。
Example 9
This example prepares a photothermal conversion film, and the specific process is different from that of example 3:
in step B1, the raw material used is an aluminum-silicon alloy powder with a silicon content of 40 wt% and a particle size of 5 μm, and the obtained porous silicon-based powder is named as 5 μm Si40-NaOH。
Example 10
This example prepares a photothermal conversion film, and the specific process is different from that of example 3:
in step B1, the raw material used is aluminum-silicon alloy powder with silicon content of 10 wt% and particle size of 74 μm, and the obtained porous silicon-based powder is named as 74 μm Si10-NaOH。
Example 11
The present embodiment provides a photothermal converter, as shown in fig. 1, the specific components and connection relationship are as follows:
the photothermal conversion film 1 (also referred to as a photothermal absorption layer) obtained in example 1 faces a light source;
a water transmission channel 3 made of a water-absorbing cotton stick, one end of which is connected with the photo-thermal conversion film 1 and the other end of which is immersed in a water body 4 to be treated;
the heat insulation layer 2 is made of melamine foam, is parallel to the liquid level on the water body 4 to be treated and the photo-thermal conversion film 1, is positioned between the liquid level on the water body 4 to be treated and the photo-thermal conversion film 1, and is penetrated through by the water transmission channel 3.
Examples 12 to 20 sequentially provide a photothermal converter, which is different from example 11 in particular in that:
the photothermal conversion films obtained in examples 2 to 10 were used as the photothermal absorption layer in this order.
Comparative example 1
This comparative example prepared a photothermal conversion film, and the specific process was different from that of example 1:
in step A1, the light absorbing material used was pure silicon powder (noted as 5 μm Si) with a particle size of 5 μm.
Comparative example 2
This comparative example prepared a photothermal conversion film, and the specific process was different from that of example 1:
in step A1, the light absorbing material used was a 5 μm particle size aluminum powder (noted as 5 μm Al).
Comparative examples 3 to 4 sequentially provide a photothermal converter, which is specifically different from example 11 in that:
the photothermal conversion films obtained in comparative examples 1 to 2 were used as the photothermal absorption layer in this order.
Test examples
In the first aspect of the present experimental example, the morphology of the silicon-based alloy powder obtained in examples 1 to 3 was tested, and the results are shown in fig. 2. The results show that the powder obtained in example 1 has a smoother surface; after the porous silicon-based powder obtained in the embodiments 2 and 3 is etched by sodium hydroxide or hydrochloric acid, pores with different sizes appear on the surface of the smooth aluminum-silicon alloy ball, and the pore diameter is 0.05-0.2 μm.
In the second aspect of the present test example, the thermal conductivity of the silicon-based alloy powder obtained in examples 1 to 3 was measured, and the results are shown in fig. 3. The results showed that the silicon-based alloy powders obtained in the examples had a thermal conductivity of 0.1419W/m.K. The heat conductivity coefficients of the porous silicon-based powder in the embodiments 2-3 are 0.0493W/m.K and 0.0661W/m.K respectively, the heat conductivity coefficient is greatly reduced and is far lower than that of a carbon-based powder material and that of a non-porous silicon-based porous material obtained in the embodiment 1, and the low heat conductivity coefficient can reduce energy loss in the photo-thermal conversion water evaporation process and improve evaporation efficiency.
In the third aspect of the present experimental example, the absorption spectra of the silicon-based alloy powders obtained in examples 1 to 4 and comparative example 1 under the wet condition were measured, and the measurement results are shown in fig. 4. The test results showed that the photothermal conversion films prepared in examples 1 to 4 had absorbances of 81.6%, 95.8%, 96.2% and 80.9% in the spectral range of 300 to 2500nm, respectively, and that the absorbance of comparative example 1 was 78.8% under the same conditions. The result shows that the light-heat conversion film prepared by taking silicon-based alloy powder (including porous and non-porous) as a light absorption material has the light absorption capacity of more than 95 percent under the multi-party synergistic effect of a porous structure, irregular pores, a plasmon effect and a non-radiative relaxation domain effect, and is obviously superior to the light absorption rate which takes silicon powder as the light absorption material, which also belongs to an extremely high level in the prior commercially successful technology; also shows that in the light absorption material provided by the invention, silicon and metal generate synergistic action, and the light absorption rate is improved.
In the fourth aspect of this test example, the photothermal converters obtained in examples 11 to 20 were tested, and when used for the treatment of water evaporated at the solar interface, the treatment effect on the water to be treated and the temperature change of the photothermal conversion film during the treatment were measured(ii) a Wherein the water body to be treated comprises pure water, lead/nickel/copper/zinc-containing heavy metal ion wastewater and 20mg/L methyl orange or methylene blue dye wastewater; the specific process is as follows: placing a photo-thermal converter containing water to be treated on an electronic balance, and adjusting an analog light source to enable the illumination intensity reaching the surface of a light absorption layer to be 1kW/m2. The test results are shown in FIGS. 5 to 9.
FIG. 5 is a graph showing the photothermal conversion film in the photothermal converters of examples 11 to 13 at a solar light intensity of 1kW/m2And (5) illuminating the surface temperature change curve. As shown in the figure, at 1kW/m2The film surface temperature of the photothermal conversion film prepared from the powders of example 1, example 2 and example 3 as the light absorbing material in light was increased to 42.5 ℃, 46.1 ℃ and 45.8 ℃ in 10min, respectively, which sufficiently shows the excellent performance of the photothermal conversion film prepared by the present invention in absorbing light energy and converting it into heat energy.
FIGS. 6 to 7 show pure water and 1kW/m of the device for treating water by solar interface evaporation including the photothermal conversion film prepared in examples 11 to 202And (3) a water body weight loss change curve under illumination.
As shown in FIG. 6, the water evaporation rates (obtained by conversion from the slope of the evaporation curve) of pure water (control group without photothermal converter) and the photothermal converters prepared in examples 11 to 13 were 0.38kg/m, respectively2h (control), 1.82kg/m2 h、2.18kg/m2h and 2.17kg/m2h; the photothermal conversion water evaporation efficiencies were calculated to be 19.34% (control), 83.21%, 91.54%, and 93.60%, respectively; compared with pure water evaporation, when the photothermal converter comprising the photothermal conversion film provided by the invention is used for water treatment by solar interface evaporation, examples 11 to 13 respectively increase the water evaporation rate by 4.79, 5.74 and 5.71 times;
as shown in FIG. 7, the light absorbing material of the photothermal converter obtained in example 14 was FeSi 2 to 4 μm6.5The water evaporation rate was 1.57kg/m2h, the result shows that the iron-silicon alloy powder also has good photo-thermal conversion water evaporation performance; example 15 the light absorbing material of the photothermal converter was 5 μm AlSi40The water evaporation rate was 1.76kg/m2h, 5 μm Al Si from example 1110Being light-absorbing materialsWater evaporation Rate (1.82 kg/m)2h) With a difference of only 0.06kg/m2h, the difference is not obvious; the light absorbing material of the photothermal converter obtained in example 16 was 74 μm AlSi10The water evaporation rate was 1.44kg/m2As compared with example 11, it is understood that the water evaporation rate of the photothermal converter tends to increase as the particle diameter of the aluminum-based alloy powder increases and decreases; examples 17 to 18 were each Si-HNO as a light-absorbing material for photothermal converters3And Si-H2C2O4The water evaporation rates were 2.1108 and 2.1102kg/m, respectively2h, showing that nitric acid and oxalic acid can be used as solutes of the etching solution; the light-absorbing materials of the photothermal converters obtained in examples 19 to 20 were each 5 μm Si40NaOH and 74 μm Si10NaOH, the water evaporation rates being 2.10 and 2.01kg/m, respectively2h, combining the results of examples 15-16, it can be seen that the porous silicon-based alloy powder prepared by using the sodium hydroxide etching solution can still be used as a light absorbing material and significantly improve the evaporation rate of water along with the change of the silicon content and the particle size in the silicon-based alloy powder. The light absorbing materials of the photothermal converters obtained in comparative examples 3 to 4 were 5 μm Si and 5 μm Al, respectively, and the water evaporation rates were 1.73kg/m, respectively2h and 1.40kg/m2h, the comparison of the test results with the test results of other examples shows that the simple substances of silicon and aluminum have certain water evaporation performance in the photothermal conversion, but the performance is not outstanding. In conclusion, the photothermal conversion film prepared by the invention is remarkably improved in water evaporation performance.
The results of fig. 6 to 7 show that the main reason for increasing the evaporation rate of pure water is that the silicon-based alloy powder and the porous silicon-based material have good light absorption capability and photo-thermal conversion capability, and particularly the porous silicon-based material has higher light absorption capability, lower thermal conductivity and excellent local heating capability, so that the photo-thermal conversion film has higher water evaporation rate and photo-thermal conversion water evaporation efficiency; meanwhile, the solar water treatment device of the photothermal converter provided by the invention greatly reduces the heat loss and improves the energy conversion efficiency from heat to water vapor.
FIG. 8 shows photothermal converters prepared in examples 11-13 at 1kW/m2And (3) a purification performance diagram of the wastewater containing the heavy metal ions under illumination.As shown in the figure, after the photothermal converter treatment in examples 11 to 13, Pb in the heavy metal ion wastewater2+、Ni2+、Cu2+And Zn2+The ion concentration of the ion is reduced by three orders of magnitude and reaches the drinking water standard concentration of the world environmental health organization (a dotted line in figure 8).
FIG. 9 shows a solar water treatment apparatus at 1kW/m including the photothermal conversion film prepared in examples 11 to 132And (3) a purification performance graph of organic dye wastewater containing methylene blue or methyl orange under illumination. As shown in the figure, the organic dye components in the methylene blue wastewater or methyl orange wastewater having a concentration of 20ppm were almost completely removed after the photothermal converter prepared in examples 11 to 13, and an extremely high organic dye purification effect was exhibited.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.