Method for the photothermolysis of organic contaminants

Abstract

The application discloses a method for photothermal degradation of organic pollutants, and particularly relates to the field of pollutant purification. The method for photothermal degradation of organic pollutants comprises the following steps: firstly, forming a composite material by mixing the organic pollutants with a photothermal conversion material; then, placing the composite material on a substrate; and finally, irradiating the composite material with a light source in a gas environment, so that the photothermal conversion material can raise the temperature of the composite material to a specific temperature, and the organic pollutants are degraded. The composite material of the photothermal conversion material and the organic pollutants can be irradiated with the light source, so that the organic pollutants can be quickly and efficiently degraded. The method has the advantages of simple process, rapid efficiency, low cost, environmental friendliness and reusability.

Description

Technical Field

[0001] This invention relates to the field of organic pollutant degradation technology, specifically a photothermal degradation method for organic pollutants. Background Technology

[0002] Organic pollutants have posed a serious threat to human health and the ecological environment, and how to achieve efficient degradation of organic pollutants has become a major challenge for environmentalists. Currently, scholars have developed various methods for degrading organic pollutants, such as advanced oxidation, photocatalysis, adsorption, biodegradation, and high-temperature incineration. However, each method has its own advantages and disadvantages, which significantly limits their practical application. Therefore, developing new methods for treating organic pollutants is both an inherent requirement of scientific and technological development and a necessary path to achieving sustainable social development.

[0003] The research group of N. Halas at Rice University points out that photothermal technology is essentially a form of heat localization (Nat. Nanotechnol., 2015, 10, 25-34). This technology refers to the phenomenon where, when photothermal materials dispersed in a medium are exposed to radiation (sunlight / laser), their temperature rises rapidly and far exceeds that of the surrounding medium. Currently, rapid heating of photothermal materials can be achieved by reducing the thermal conductivity of the medium surrounding them. For example, Li et al. (Green Chem., 2018, 20, 2857-2869) reported a platinum nanocatalyst (Pt-CeO2) partially embedded in the mesopores of cerium dioxide, which can reach a photothermal temperature of up to 767 °C under xenon lamp irradiation; Roberto et al. irradiated randomly arranged silicon nanowires with a 532 nm laser and found that their surface temperature could rise to 600 °C within a few seconds (J. Phys. Chem. C, 2021, 125, 14134-14140); He et al. constructed a photothermal catalyst of porous silica encapsulated nickel metal nanoparticles (Ni@p-SiO2), which could rapidly raise the surface temperature of nickel particles to 579 °C under xenon lamp irradiation (Nat. Energy, 2021, 6, 807-814). Regarding the thermal degradation temperature of dye molecules, Saleh et al. conducted a detailed analysis of the thermal degradation process of azo dyes based on thermogravimetric analysis, finding that most organic pollutants completely degrade at around 300 °C (Results Chem., 2020, 2, 100085). Therefore, existing photothermal technology can generate sufficiently high temperatures to meet the temperature requirements for the thermal degradation of organic pollutants.

[0004] Currently, preliminary research has been conducted on photothermal technology for pollutant degradation. For example, Wu Xinglong's research group found that the photothermal effect caused by infrared irradiation can enhance the carrier migration rate of the catalyst, thereby increasing the degradation rate of methylene blue dye by 38%. However, this technology does not directly cause the dye molecules to undergo thermal degradation (ACS Nano, 2014, 8, 9304-9310). Sheng and Zhang et al. respectively confirmed that the photothermal effect indirectly participates in the dye degradation process by enhancing the generation rate or oxidation capacity of active free radicals, rather than directly creating a high-temperature environment to thermally degrade the dye (Chem.Eng. J., 2021, 403, 126324; Environ. Sci.: Nano, 2022, 9, 532-541). A review of the above literature shows that: (1) current photothermal technologies are all applied in water systems, and photothermal technologies all indirectly degrade pollutants by inducing the generation of active species; (2) the types of organic pollutants that can be degraded are limited to organic dyes, and the types of degradable substances are limited.

[0005] Therefore, developing novel photothermal degradation methods for organic pollutants to achieve rapid and efficient degradation of a wider range of organic pollutants is one of the most important issues that urgently needs to be addressed in the environmental protection field.

[0006] In summary, by utilizing the localized nature of photothermal conversion heat, this invention develops a novel method for the photothermal degradation of organic pollutants, aiming to achieve rapid and efficient degradation of organic pollutants. This method will have a positive impact on the advancement of environmental protection technologies and possesses significant theoretical value and application prospects. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a photothermal degradation method for organic pollutants, which utilizes photothermal conversion heat to rapidly and efficiently degrade various organic pollutants, and is not limited to applications in water systems.

[0008] To achieve the above objectives, the specific solution adopted by the present invention is as follows: A photothermal degradation method for organic pollutants mainly includes the following steps: Step 1: Combine organic pollutants with photothermal conversion materials to form composite materials; Step 2: Place the composite material on the substrate; Step 3: In a gaseous environment, the composite material is irradiated by a light source. Under the action of the light source, the photothermal conversion material generates local high temperature, which can cause the organic pollutants to undergo thermal decomposition.

[0009] Furthermore, in step one, the photothermal conversion material is any one of carbon-based materials, metals and their composites based on the plasma resonance effect, chalcogenide compounds, and transition metal carbonitrides.

[0010] Furthermore, the organic pollutants are any one of dyes, antibiotics, plastics, polycyclic aromatic hydrocarbons, organohalides, flame retardants, and pesticides.

[0011] Furthermore, in step one, the mass ratio of photothermal conversion material to organic pollutants in the composite material is 0.01 to 100; the method of preparing the composite material from photothermal conversion material and organic pollutants includes any one of direct physical blending, mixed solution blending and drying, physical adsorption, and chemical adsorption.

[0012] Furthermore, the mixed solution co-drying involves dissolving organic pollutants in a solvent to obtain a first solution; dissolving the photothermal conversion material in a solvent to obtain a second solution; mixing the first and second solutions thoroughly; and then performing a drying process. The solvents used in preparing the first and second solutions are any one of water, methanol, ethanol, and dichloromethane.

[0013] Furthermore, in step two, the substrate is selected from solid materials with a thermal conductivity of less than 10 W / (m·K); The substrate material can be any one of silica aerogel, asbestos mesh, or refractory material.

[0014] Furthermore, in step three, the light source includes any one of infrared laser, visible laser, ultraviolet laser, or solar beam formed by focusing material; When infrared, visible, or ultraviolet lasers are used as the light source, the laser source power is 0.01~3.00 W / cm². 2 ; When the light source is a solar beam formed by a focusing material, the solar irradiance is 0.01~0.15 W / cm². 2 The optical focusing ratio of the focusing material is 3~30.

[0015] Furthermore, in step three, the gaseous environment is at least one of air, nitrogen, argon, and carbon dioxide.

[0016] Beneficial effects: (1) The photothermal degradation method for organic pollutants provided by the present invention does not require fossil energy and electricity to provide high temperature. It can achieve dye degradation only through light source, which has the advantages of being green and pollution-free.

[0017] (2) The photothermal degradation method for organic pollutants provided by the present invention can achieve the degradation of all kinds of organic pollutants.

[0018] (3) The photothermal degradation method for organic pollutants provided by the present invention has the advantages of simple operation, low cost, environmental friendliness and reusability, which is conducive to its promotion and application. Attached Figure Description

[0019] Figure 1 These are TEM images of three-dimensional ordered macroporous carbon from Examples 1 and 2.

[0020] Figure 2 These are infrared thermal images of the three-dimensional ordered macroporous carbon from Examples 1 and 2 after laser irradiation.

[0021] Figure 3 These are UV-Vis images of Congo Red dye before and after degradation in Example 1.

[0022] Figure 4 These are UV-Vis images of Congo Red dye before and after degradation in Example 2.

[0023] Figure 5 These are TEM images of graphene from Examples 3 and 5.

[0024] Figure 6 These are UV-Vis images of sulfathiazole before and after degradation in Example 4.

[0025] Figure 7 These are UV-Vis images of Congo Red dye before and after degradation in Example 5.

[0026] Figure 8 This is a TEM image of the copper sulfide nanoparticles in Example 6.

[0027] Figure 9 This is a TEM image of the gold nanoparticles in Example 7. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0029] This invention provides a method for photothermal degradation of organic pollutants, mainly comprising the following steps: Step 1: Combine organic pollutants with photothermal conversion materials to form composite materials; Step 2: Place the composite material on the substrate; Step 3: In a gaseous environment, the composite material is irradiated with a light source for a certain period of time (e.g., 1 s to 259200 s). The light source directly irradiates the composite material on the substrate. The photothermal conversion material component in the composite material converts light energy into heat energy. At the same time, the substrate with low thermal conductivity and the surrounding contact gas have difficulty conducting heat quickly, resulting in local high temperature in the photothermal conversion material. When the local temperature is higher than the thermal decomposition temperature of organic pollutants, the organic pollutants will undergo thermal decomposition, thereby achieving the degradation of organic pollutants.

[0030] The following section elaborates on the substances involved in the photothermal degradation method for organic pollutants.

[0031] <Composite Materials> In composite materials, the mass ratio of photothermal conversion material to organic pollutants is 0.01 to 100.

[0032] Among them, photothermal conversion materials include, but are not limited to, carbon-based materials (such as carbon quantum dots, graphene, activated carbon, carbon nanotubes, porous carbon, etc.), metals and their composite materials based on the plasma resonance effect (such as gold, silver, etc.), chalcogenide compounds (such as black titanium dioxide, copper sulfide, etc.), transition metal carbonitrides, and other materials that can convert light energy into heat energy.

[0033] The ways in which photothermal conversion materials and organic pollutants form composite materials include, but are not limited to, direct physical blending, mixed solution blending and drying, physical adsorption, or chemical adsorption.

[0034] The mixed solution co-drying process involves dissolving organic pollutants in a solvent to obtain a first solution, dissolving photothermal conversion materials in a solvent to obtain a second solution, mixing the first and second solutions thoroughly, and then performing a drying process. The solvents used in preparing the first and second solutions are any one of water, methanol, ethanol, dichloromethane, etc.

[0035] <Substrate> The substrate material is a solid material with a thermal coefficient of less than 10 W / (m·K), including but not limited to silica aerogel, asbestos mesh, refractory materials, etc.

[0036] <Light Source> In this invention, the light source includes, but is not limited to, infrared lasers (such as 1064 nm, 980 nm), visible lasers (such as 660 nm), ultraviolet lasers (such as 248 nm), and solar beams formed by focusing materials (such as Fresnel lenses), wherein the laser source power is between 0.01 and 3.00 W / cm². 2 The solar irradiance is 0.01~0.15 W / cm². 2 The optical focusing ratio of the focusing material is between 3 and 30.

[0037] <Gas Environment> The gaseous environment is at least one of the following gases: air, nitrogen, argon, carbon dioxide, etc.

[0038] The photothermal degradation method of the present invention can degrade organic pollutants including, but not limited to, dyes, antibiotics, plastics (including microplastics), polycyclic aromatic hydrocarbons, organohalides, flame retardants, and pesticides.

[0039] The technical solution of the present invention will be described in detail below with reference to specific embodiments. It should be noted that all raw materials in the following embodiments are commercially available.

[0040] Example 1 This embodiment provides a method for photothermal degradation of organic pollutants, which mainly includes the following steps: Step 1: Combine organic pollutants (40 mg Congo red dye) with photothermal conversion material (10 mg three-dimensional ordered macroporous carbon; TEM image as shown). Figure 1 A composite material (the mass ratio of photothermal conversion material to organic pollutants is 0.25) is prepared by physical blending. Step 2: Place the composite material on a silica aerogel substrate; Step 3: In an air environment, using a light source (power 0.94 W / cm²) 2 Irradiating the composite material with a visible laser (wavelength 660 nm) for 180 seconds raises the temperature of the composite material to approximately 400℃. (See attached image) Figure 2 The temperature is higher than the thermal degradation temperature of Congo red (approximately 278°C), and the degradation rate of Congo red dye is 15.86% (see attached image). Figure 3 ).

[0041] Example 2 This embodiment provides a method for photothermal degradation of organic pollutants, which mainly includes the following steps: Step 1: Combine organic pollutants (40 mg Congo red dye) with photothermal conversion material (10 mg three-dimensional ordered macroporous carbon; TEM image as shown). Figure 1 A composite material (the mass ratio of photothermal conversion material to organic pollutants is 0.25) is prepared by physical blending. Step 2: Place the composite material on a silica aerogel substrate; Step 3: In a mixed gas environment (composed of 20% oxygen and 80% nitrogen), use a light source (power 0.94 W / cm²) 2 Irradiating the composite material with an infrared laser (wavelength 980 nm) for 300 seconds raises the temperature of the composite material to approximately 400℃. (See attached image) Figure 2The temperature is higher than the thermal degradation temperature of Congo red (approximately 278°C), and the degradation rate of Congo red dye is 57.19% (see attached figure). Figure 4 ).

[0042] Example 3 This embodiment provides a method for photothermal degradation of organic pollutants, which mainly includes the following steps: Step 1: Mix organic pollutants (30 mg sulfathiazole antibiotics) with photothermal conversion material (10 mg graphene; TEM image as shown) Figure 5 A composite material (the mass ratio of photothermal conversion material to organic pollutants is 0.33) is prepared by physical blending. Step 2: Place the composite material on an asbestos mesh substrate; Step 3: In a nitrogen atmosphere, use a light source (power 0.7 W / cm²) 2 The composite material was irradiated with an infrared laser (wavelength 1064 nm) for 180 seconds, causing the temperature of the composite material to rise to approximately 220°C, which is higher than the thermal degradation temperature of sulfathiazole (approximately 178°C). The degradation rate of sulfathiazole was 67.47%. (See attached image) Figure 6 ).

[0043] Example 4 This embodiment provides a method for photothermal degradation of organic pollutants, which mainly includes the following steps: Step 1: Combine organic pollutants (40 mg Congo red dye) with photothermal conversion material (10 mg three-dimensional ordered macroporous carbon; TEM image as shown). Figure 1 A composite material (the mass ratio of photothermal conversion material to organic pollutants is 0.25) is prepared by physical blending. Step 2: Place the composite material on a silica aerogel substrate; Step 3: In the air environment, use a light source (a solar beam formed by a focusing material, with a power of 0.09 W / cm²) 2 (The Fresnel lens has an optical focusing ratio of 10.) After irradiating the composite material for 600 s, the temperature of the composite material rises to about 385℃, which is higher than the thermal degradation temperature of Congo red (about 278℃). The degradation rate of Congo red dye is 61.21% (see attached image). Figure 7 ).

[0044] Example 5 This embodiment provides a method for photothermal degradation of organic pollutants, which mainly includes the following steps: Step 1: Mix organic pollutants (5 mg bisphenol A) with photothermal conversion material (10 mg graphene). TEM image as shown. Figure 5 A composite material (the mass ratio of photothermal conversion material to organic pollutants is 2) is prepared by physical blending. Step 2: Place the composite material on a silica aerogel substrate; Step 3: In an air environment, using a light source (power 0.35 W / cm²) 2 The composite material was irradiated with a visible laser with a wavelength of 660 nm for 180 s, and the temperature of the composite material rose to about 210℃, which is higher than the thermal degradation temperature of bisphenol A (about 201℃). The degradation rate of bisphenol A was 72%.

[0045] Example 6 This embodiment provides a method for photothermal degradation of organic pollutants, which mainly includes the following steps: Step 1: Mix organic pollutants (1 mg bis(4-bromophenyl) ether) with photothermal conversion materials (5 mg copper sulfide nanoparticles). TEM image as shown. Figure 8 A composite material (the mass ratio of photothermal conversion material to organic pollutants is 5) is prepared by physical blending. Step 2: Place the composite material on a substrate made of alumina-based refractory material; Step 3: In an air environment, using a light source (power 1 W / cm²) 2 The composite material was irradiated with an infrared laser with a wavelength of 980 nm for 6000 seconds, and the temperature of the composite material rose to about 245℃, which is higher than the thermal degradation temperature of bis(4-bromophenyl) ether (about 182℃). The degradation rate of bis(4-bromophenyl) ether was 81%.

[0046] Example 7 This embodiment provides a method for photothermal degradation of organic pollutants, which mainly includes the following steps: Step 1: Mix organic pollutants (0.1 mg pentachlorophenol) with photothermal conversion materials (1 mg gold nanoparticles; TEM image as shown) Figure 9 A composite material (the mass ratio of photothermal conversion material to organic pollutants is 10) is prepared by physical blending. Step 2: Place the composite material on a silica aerogel substrate; Step 3: In the air environment, use a light source (a solar beam formed by a focusing material, with a power of 0.07 W / cm²) 2 (The optical focusing ratio of the Fresnel lens is 20) Irradiate the composite material for 60 s, and the temperature of the composite material rises to about 330℃, which is higher than the thermal degradation temperature of pentachlorophenol (about 280℃). The degradation rate of pentachlorophenol is 99.4%.

[0047] Example 8 This embodiment provides a method for photothermal degradation of organic pollutants, which mainly includes the following steps: Step 1: Organic pollutants (an aqueous solution containing 400 mg tetracycline) and photothermal conversion material (an aqueous solution containing 10 mg molybdenum disulfide) are mixed and dried to form a composite material (the mass ratio of photothermal conversion material to organic pollutants is 0.025). Step 2: Place the composite material on a silica aerogel substrate; Step 3: In an air environment, use a light source (power 2 W / cm²) 2 The composite material was irradiated with an ultraviolet laser with a wavelength of 248 nm for 180 s, and the temperature of the composite material rose to about 250℃, which is higher than the thermal degradation temperature of tetracycline (about 225℃). The degradation rate of tetracycline was 4%.

[0048] Example 9 This embodiment provides a method for photothermal degradation of organic pollutants, which mainly includes the following steps: Step 1: Organic pollutants (an aqueous solution containing 0.5 mg of Coomassie brilliant blue dye) and photothermal conversion material (an ethanol solution containing 10 mg of carbon nanotubes) are mixed and dried to prepare a composite material (the mass ratio of photothermal conversion material to organic pollutants is 20). Step 2: Place the composite material on a silica aerogel substrate; Step 3: In an air environment, use a light source (power 2.5 W / cm²) 2 The composite material was irradiated with an infrared laser with a wavelength of 1064 nm for 10,000 seconds, and the temperature of the composite material rose to about 520°C, which is higher than the thermal degradation temperature of Coomassie Brilliant Blue (about 470°C). The degradation rate of Coomassie Brilliant dye was 98.5%.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for photothermal degradation of organic pollutants, characterized in that, The main steps include the following: Step 1: Combine organic pollutants with photothermal conversion materials to form composite materials; Step 2: Place the composite material on the substrate; Step 3: In a gaseous environment, the composite material is irradiated by a light source. Under the action of the light source, the photothermal conversion material generates local high temperature, which can cause the organic pollutants to undergo thermal decomposition.

2. The photothermal degradation method for organic pollutants according to claim 1, characterized in that, In step one, the photothermal conversion material is any one of the following: carbon-based materials, metals and their composites based on the plasma resonance effect, chalcogenide compounds, and transition metal carbonitrides.

3. The photothermal degradation method for organic pollutants according to claim 1, characterized in that, Organic pollutants are any one of dyes, antibiotics, plastics, polycyclic aromatic hydrocarbons, organohalides, flame retardants, and pesticides.

4. The photothermal degradation method for organic pollutants according to claim 1, characterized in that, In step one, the mass ratio of photothermal conversion material to organic pollutants in the composite material is 0.01~100; The methods for preparing composite materials from photothermal conversion materials and organic pollutants include any one of the following: direct physical blending, mixed solution blending and drying, physical adsorption, and chemical adsorption.

5. The photothermal degradation method for organic pollutants according to claim 4, characterized in that, The mixed solution co-drying process involves dissolving organic pollutants in a solvent to obtain a first solution, dissolving photothermal conversion materials in a solvent to obtain a second solution, mixing the first and second solutions thoroughly, and then performing a drying process. The solvents used in preparing the first and second solutions are any one of water, methanol, ethanol, and dichloromethane.

6. The photothermal degradation method for organic pollutants according to claim 1, characterized in that, In step two, a solid material with a thermal conductivity of less than 10 W / (m·K) is selected as the substrate.

7. The method for photothermal degradation of organic pollutants according to claim 1, characterized in that, In step three, the light source includes any one of infrared laser, visible laser, ultraviolet laser, or solar beam formed by focusing material; When the light source adopts infrared laser, visible laser or ultraviolet laser, the power of the laser light source is 0.01-3.00 W / cm 2 ; When the light source adopts a solar beam formed by focusing material, the solar irradiation power is 0.01-0.15 W / cm 2 , and the optical concentration ratio of the focusing material is 3-30.

8. The photothermal degradation method for organic pollutants according to claim 1, characterized in that, In step three, the gaseous environment is at least one of air, nitrogen, argon, and carbon dioxide.

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