A composite photothermal film, a preparation method thereof, and a high-salinity wastewater treatment device containing the composite photothermal film
By loading carbon/iron sulfides onto a hydrophilic filter membrane to form a hydrophobically modified Janus structure composite photothermal membrane, the high cost and secondary pollution problems of ammonium sulfate wastewater treatment in the prior art are solved, and efficient photothermal evaporation and resource utilization are realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING UNIV OF SCI & TECH
- Filing Date
- 2024-11-01
- Publication Date
- 2026-06-23
AI Technical Summary
Existing technologies for treating ammonium sulfate wastewater from biomass energy, amino alcohol production, and fuel cell production suffer from several drawbacks: calcium hydroxide precipitation generates secondary pollution; ion exchange is costly; electrodialysis is energy-intensive and has a narrow applicability; and reverse osmosis is susceptible to changes in water quality. Furthermore, there is a lack of efficient solar interface evaporation technology.
A composite photothermal membrane is used, which uses a hydrophilic filter membrane as a carrier, loads carbon/iron sulfides, and forms a Janus structure through hydrophobic modification. It is used in high-salt wastewater treatment devices, including the design of a reaction chamber, a water transport layer, a salt collection layer, and a heat insulation layer.
It achieves a high-efficiency photothermal evaporation rate and photothermal conversion efficiency, enabling the purification of ammonium sulfate wastewater and the production of ammonium sulfate crystals under sunlight, thereby reducing production costs and realizing the resource utilization of waste.
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Figure CN119390166B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a composite photothermal film, a method for preparing the composite photothermal film, and a high-salt wastewater treatment device containing the composite photothermal film, belonging to the field of high-salt wastewater treatment technology. Background Technology
[0002] Wastewater discharged from processes such as biomass energy production, amino alcohol production, and fuel cell production typically contains large amounts of ammonium sulfate. If not properly treated, it may release ammonia gas, polluting the air and harming human health.
[0003] Currently, common methods for desalination of ammonium sulfate wastewater include reverse osmosis, electrodialysis, ion exchange, evaporation crystallization, and calcium hydroxide precipitation. However, calcium hydroxide precipitation produces a large amount of precipitate, which may cause secondary pollution; ion exchange requires regular resin replacement, and waste resin disposal is complex and costly; electrodialysis has high energy consumption and a narrow range of applications; reverse osmosis is easily affected by water quality changes and produces a large amount of concentrated wastewater that needs treatment, resulting in high operating costs; evaporation crystallization has high treatment efficiency but high energy consumption.
[0004] Solar interface technology utilizes solar energy to heat and evaporate wastewater, thereby efficiently removing impurities and dissolved substances. Currently, there are no reports of using solar interface evaporation technology to treat ammonium sulfate wastewater. Summary of the Invention
[0005] Purpose of the invention: The purpose of this invention is to provide a composite photothermal film with excellent photothermal evaporation rate and photothermal conversion efficiency; another purpose of this invention is to provide a method for preparing the above-mentioned composite photothermal film and a high-salt wastewater treatment device containing the above-mentioned composite photothermal film.
[0006] Technical solution: The composite photothermal film of the present invention uses a hydrophilic filter membrane as a carrier, and carbon / iron sulfides are loaded on the carrier; wherein, the side of the hydrophilic filter membrane loaded with carbon / iron sulfides is grafted with hydrophobic groups.
[0007] The loading of carbon / iron sulfides on the carrier is 1–3 mg / cm³. 2 .
[0008] The preparation method of the above-mentioned composite photothermal film includes the following steps:
[0009] (1) Heat treatment of coal slime to obtain coal-based carbon materials;
[0010] (2) The carbonized coal slime from step (1) is mixed with pyrite, and then calcined at high temperature under an inert atmosphere to obtain carbon / iron sulfide powder.
[0011] (3) Disperse the carbon / iron sulfide powder from step (2) in a solvent, sonicate it, and then load the carbon / iron sulfide onto a hydrophilic filter membrane by vacuum filtration.
[0012] (4) The hydrophilic filter membrane obtained in step (3) is modified by vacuum filtration with a polyethylene glycol solution containing a hydrophobic agent to obtain a composite photothermal membrane with a Janus structure having a hydrophobic surface and a hydrophilic bottom layer; wherein the side loaded with carbon / iron sulfide is the hydrophobic side.
[0013] If the composite photothermal film is not modified to be hydrophobic, salt crystals will precipitate on the film surface, affecting both evaporation and salt crystal collection.
[0014] In step (2), the mixing mass ratio of pyrite and carbonized coal slime is 1:2; the calcination temperature is 500-1000℃ and the calcination time is 5-8h.
[0015] In step (3), the hydrophilic filter membrane is one of polyethersulfone filter membrane, PVDF membrane, cellulose acetate filter membrane, mixed cellulose filter membrane or nitrocellulose filter membrane.
[0016] In step (4), the hydrophobic agent is a mixture of glacial acetic acid, trimethoxy(1H,1H,2H,2H-heptadecyl)silane and isopropanol in a volume ratio of 0.1-2.0:0.5-2.0:96.0-98.0.
[0017] In step (4), the volume ratio of the hydrophobic agent to the polyethylene glycol solution is 1:80-100.
[0018] A high-salt wastewater treatment device containing the aforementioned composite photothermal membrane includes a reaction chamber for holding the wastewater to be treated and a water transport layer for transporting the wastewater to the composite photothermal membrane; the composite photothermal membrane is laid above the wastewater to be treated in the reaction chamber; it also includes a water guiding layer and a salt collecting layer, the composite photothermal membrane is disposed in the central region of the water guiding layer, the salt collecting layer is laid on the side of the water guiding layer away from the photothermal membrane, and the coverage area of the salt collecting layer is the periphery of the area where the photothermal membrane is placed in the water guiding layer.
[0019] It also includes a heat insulation layer, which is fixed on the reaction chamber. A water transport layer passes through the heat insulation layer and is connected to the water guiding layer, which transports water to the composite photothermal film.
[0020] The water transport layer and water guiding layer are both non-woven fabric, terry cloth or super absorbent non-woven fabric; the heat insulation layer is one of polystyrene foam, polyurethane foam or polyisocyanate foam; the salt collection layer is a metal plate, glass plate or plastic plate.
[0021] The composite photothermal membrane prepared in this invention modifies one side of the hydrophilic filter membrane by forming hydrophobic substances (silicon-oxygen bonds), resulting in a Janus structure with a hydrophilic bottom layer and a hydrophobic surface layer. This prevents wetting of the membrane surface and improves the membrane's resistance to salt deposition. When treating saline wastewater, it confines water evaporation within the membrane, promoting spontaneous downward diffusion of salt and preventing salt condensation on the membrane surface. This ensures the stability of the membrane structure and evaporation efficiency, enabling the membrane to maintain a high evaporation rate even during long-term continuous operation.
[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The composite photothermal film prepared by the present invention has excellent photothermal evaporation rate, photothermal conversion efficiency and performance stability. It can be applied to the construction of interface evaporation device, and under the drive of sunlight, it can purify ammonium sulfate wastewater and obtain ammonium sulfate crystals, realizing the diversified utilization of high-salt wastewater. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the high-salinity wastewater treatment device in Embodiment 1 of the present invention;
[0024] Figure 2 The wastewater mass change curves of 10wt% ammonium sulfate wastewater treated by composite photothermal films formed from carbon / iron sulfides obtained at different calcination temperatures for 2 hours under 1 sun irradiation.
[0025] Figure 3 A comparison of the evaporation rate and photothermal conversion efficiency of composite photothermal films formed from carbon / iron sulfides obtained at different calcination temperatures when treating 10wt% ammonium sulfate wastewater for 2 hours under 1sun irradiation.
[0026] Figure 4 The wastewater mass change curves of 10wt% ammonium sulfate wastewater treated with different photothermal films for 2 hours under 1 sun irradiation;
[0027] Figure 5 The bar chart shows the evaporation rate at different times when the composite photothermal film of Example 1 treats 10wt% ammonium sulfate wastewater under 1sun irradiation.
[0028] Figure 6 This is a photograph of the hydrophobically modified composite photothermal film (circular) prepared in Example 1, with a drop of water placed on its surface. Detailed Implementation
[0029] Example 1
[0030] The method for preparing the composite photothermal film of the present invention includes the following steps:
[0031] (1) Preparation of carbonized coal slime: 0.5g of coal slime was placed in a porcelain boat and placed in a tube furnace, and calcined at 800℃ for 2h under nitrogen conditions (heating rate of 5℃·min). -1 (Cooling method is natural cooling), after calcination, it is taken out and ground to obtain carbonized coal slime powder;
[0032] (2) Preparation of carbon / iron sulfide (carbon composite iron sulfide): 30 mg of carbonized coal slime and pyrite were dissolved in 100 mL of isopropanol aqueous solution (prepared by mixing 60 mL of isopropanol and 40 mL of water) at a mass ratio of 2:1. After ultrasonic dispersion, the mixed solid material was collected by vacuum filtration and dried in an oven at 60℃ for 2 h. Then, it was calcined in a tube furnace at 600℃ for 6 h (under nitrogen conditions, with a heating rate of 5℃·min). -1 (The cooling method is natural cooling), and after calcination, it is taken out to obtain carbon / iron sulfide powder;
[0033] (3) Take 30 mg of carbon / iron sulfide powder and disperse it in 100 mL of isopropanol solution, wherein the isopropanol solution is prepared by 60 mL of isopropanol and 40 mL of water; after ultrasonic stirring for 30 min; the carbon / iron sulfide is loaded onto the PVDF membrane by vacuum filtration.
[0034] (4) Mix 5 mL of polyethylene glycol and 20 mL of deionized water evenly to obtain a polyethylene glycol solution; add 250 μL of hydrophobic agent (the hydrophobic agent is composed of 50 μL of glacial acetic acid, 200 μL of trimethoxy(1H,1H,2H,2H-heptadecyl)silane and 9.75 mL of isopropanol) to the polyethylene glycol solution to obtain a mixed solution, and load it onto the surface of the PVDF membrane obtained in step (3) by vacuum filtration to obtain a composite photothermal membrane with a hydrophobic surface layer and a hydrophilic Janus structure in the lower layer; wherein, the loading of carbon / iron sulfide on the PVDF membrane is 2.39 mg / cm³. 2 .
[0035] pass Figure 6 It can be seen that the PVDF membrane prepared by the present invention has good hydrophobic properties on the side (upper surface) loaded with carbon / iron sulfides after hydrophobic modification treatment.
[0036] Example 2
[0037] like Figure 1As shown, a high-salt wastewater treatment device containing the composite photothermal membrane of Example 1 is constructed, including a reaction chamber for holding the wastewater to be treated and a heat insulation layer placed on the reaction chamber; it also includes a composite photothermal membrane, a water guiding layer, a salt collecting layer and a water transport layer; one end of the water transport layer is located in the wastewater, and the other end passes through the heat insulation layer and is connected to the water guiding layer. The water guiding layer is laid on the heat insulation layer, the composite photothermal membrane is laid in the central area of the water guiding layer, and the salt collecting layer is laid on the side of the water guiding layer away from the photothermal membrane. The coverage area of the salt collecting layer is the periphery of the area where the photothermal membrane is placed in the water guiding layer.
[0038] The composite photothermal film, square in shape, is laid in the central area of the water guiding layer. The water guiding layer is an irregularly shaped non-woven fabric used to store and transfer water from the water transport layer to the composite photothermal film. The center of the irregularly shaped water guiding layer is square, used to place the composite photothermal film. Each side of the square water guiding layer extends into a trapezoidal structure. The salt collection layer is laid in the corresponding trapezoidal structure area of the water guiding layer, away from the side of the photothermal film. The heat insulation layer is made of polystyrene foam, used to avoid errors caused by water evaporation due to direct sunlight. The water transport layer is made of non-woven fabric, through which ammonium sulfate wastewater passes from the non-woven fabric (water transport layer) through the heat insulation layer to the water guiding layer, ensuring a sufficient water source during the interface evaporation process. Between the water guiding layer and the heat insulation layer, aluminum foil is laid under the trapezoidal portion extending from the central square of the water guiding layer to receive salt crystals formed at the edge of the composite photothermal film during the interface evaporation process.
[0039] The high-salinity wastewater treatment device from Example 2 was applied to treat 10wt% ammonium sulfate wastewater for 2 hours under 1sun irradiation. Comparing the changes in water quality before and after the experiment, it was found that the evaporation rate of the composite photothermal film was 1.93 kg·m³. -2 ·h -1 The photothermal conversion efficiency is 113.6%.
[0040] Comparative Example 1
[0041] The method of preparing the composite photothermal film in Comparative Example 1 is basically the same as that in Example 1, the only difference is that in step (2), the calcination temperature is 300℃ to obtain the composite photothermal film.
[0042] Comparative Example 2
[0043] The method of preparing the composite photothermal film in Comparative Example 2 is basically the same as that in Example 1, the only difference is that in step (2), the calcination temperature is 450℃ to obtain the composite photothermal film.
[0044] Comparative Example 3
[0045] The method of preparing the composite photothermal film in Comparative Example 3 is basically the same as that in Example 1, the only difference is that in step (2), the calcination temperature is 800℃ to obtain the composite photothermal film.
[0046] Comparative Example 4
[0047] The method of constructing the high-salt wastewater treatment device in Comparative Example 4 is basically the same as that in Example 2, the only difference is that the composite photothermal film is not laid in the central area of the water guiding layer and no light source is added.
[0048] Comparative Example 5
[0049] The method of constructing the high-salt wastewater treatment device in Comparative Example 5 is basically the same as that in Example 2, the only difference being that a pure PVDF membrane (without carbon / iron sulfide materials and without hydrophobic modification) is laid in the central area of the water guiding layer.
[0050] Comparative Example 6
[0051] The methods for constructing the high-salt wastewater treatment device in Comparative Example 6 and Example 2 are basically the same, with the only difference being that a carbonized coal sludge membrane is laid in the central region of the water guiding layer. The preparation method of the carbonized coal sludge membrane is basically the same as that of the composite photothermal membrane in Example 1, with the only difference being that pyrite is not added in step (2) to obtain the carbonized coal sludge membrane, and the loading of coal-based carbon on the PVDF membrane is the same as the loading of carbon / iron sulfides in Example 1.
[0052] A high-salt wastewater treatment device was constructed using the photothermal membranes of Examples 1 and 1-3, following the same construction process as in Example 2. Figure 2 , Figure 3 It can be observed that the evaporation rate and photothermal conversion efficiency of the composite photothermal film obtained at 300℃, 450℃, 600℃, and 800℃ are 1.42 kg·m³, respectively. -2 ·h -1 and 82.5%, 1.77 kg·m -2 ·h -1 and 100.7%, 1.93 kg·m -2 ·h -1 and 113.6%, 1.71 kg·m -2 ·h -1 With an evaporation rate of 105.2%, the composite photothermal film prepared in Example 1 has the fastest evaporation rate and the best photothermal conversion efficiency.
[0053] The evaporation rate of the high-salt wastewater treatment devices constructed in Comparative Examples 2 and 5-6 after treating 10wt% ammonium sulfate wastewater for 2 hours under 1 sun irradiation was compared with that of the devices in Comparative Examples 5-6. Figure 4 It can be seen that the evaporation rate of the ammonium sulfate wastewater obtained by the treatment device constructed in Comparative Example 4 is 0.34 kg·m³. -2 ·h -1 The evaporation rate of the pure PVDF membrane treatment device constructed in Comparative Example 5 was 0.88 kg·m³. -2 ·h-1 The evaporation rate of the carbonized coal slurry membrane treatment device constructed in Comparative Example 6 was 1.32 kg·m³. -2 ·h -1 The evaporation rate of the composite photothermal film treatment device prepared in Example 2 was 1.93 kg·m³. -2 ·h -1 .
[0054] The high-salt wastewater treatment device prepared in Example 1 was applied to treat 10wt% ammonium sulfate wastewater under 1sun irradiation. The evaporation rate of the device at different operating times was compared. Figure 5 It can be seen that, under continuous operation for up to 12 hours, the evaporation rate of the device is approximately 1.93 kg·m³. -2 ·h -1 It fluctuates up and down, and the range of fluctuation is very small.
[0055] The photothermal material of this invention is made by high-temperature calcination of coal slime and pyrite. Coal slime is a solid waste. After high-temperature calcination, the resulting composite material has excellent photothermal efficiency and stability, which not only reduces production costs but also realizes the resource utilization of waste and reduces environmental pollution.
Claims
1. A composite photothermal film, characterized in that: The composite photothermal film uses a hydrophilic filter membrane as a carrier, on which carbon / iron sulfides are loaded; wherein, the side of the hydrophilic filter membrane loaded with carbon / iron sulfides is grafted with hydrophobic groups. The preparation method of the above-mentioned composite photothermal film includes the following steps: (1) Heat treatment of coal slime to obtain coal-based carbon materials; (2) The carbonized coal slime from step (1) is mixed with pyrite, and then calcined at high temperature under an inert atmosphere to obtain carbon / iron sulfide powder. (3) Disperse the carbon / iron sulfide powder from step (2) in a solvent, sonicate it, and then load the carbon / iron sulfide onto a hydrophilic filter membrane by vacuum filtration. (4) The hydrophilic filter membrane obtained in step (3) is modified by vacuum filtration of a polyethylene glycol solution containing a hydrophobic agent to make one side hydrophobic, so as to obtain a composite photothermal membrane with a Janus structure having a hydrophobic surface and a hydrophilic bottom layer; wherein the side loaded with carbon / iron sulfide is the hydrophobic side.
2. The composite photothermal film according to claim 1, characterized in that: The loading of carbon / iron sulfide on the carrier is 1~3 mg / cm³. 2 .
3. The composite photothermal film according to claim 1, characterized in that: In step (2), the mass ratio of pyrite and carbonized coal slime is 1:2; the calcination temperature is 500~1000℃ and the calcination time is 5~8h.
4. The composite photothermal film according to claim 1, characterized in that: In step (3), the hydrophilic filter membrane is one of polyethersulfone filter membrane, PVDF membrane, cellulose acetate filter membrane, mixed cellulose filter membrane or nitrocellulose filter membrane.
5. The composite photothermal film according to claim 1, characterized in that: In step (4), the hydrophobic agent is a mixture of glacial acetic acid, trimethoxy(1H,1H,2H,2H-heptadecyl)silane and isopropanol in a volume ratio of 0.1~2.0:0.5~2.0:96.0~98.
0.
6. The composite photothermal film according to claim 1, characterized in that: In step (4), the volume ratio of the hydrophobic agent to the polyethylene glycol solution is 1:80~100.
7. A high-salinity wastewater treatment device using the composite photothermal film as described in claim 1, characterized in that: It includes a reaction chamber for holding wastewater to be treated and a water transport layer for transporting the wastewater to a composite photothermal membrane; the composite photothermal membrane is laid on top of the wastewater to be treated in the reaction chamber; it also includes a water guiding layer and a salt collecting layer, the composite photothermal membrane is disposed in the central area of the water guiding layer, the salt collecting layer is laid on the side of the water guiding layer away from the photothermal membrane, and the area covered by the salt collecting layer is the periphery of the area where the photothermal membrane is placed in the water guiding layer.
8. The high-salinity wastewater treatment device according to claim 7, characterized in that: It also includes a heat insulation layer, which is placed on the reaction chamber. A water transport layer passes through the heat insulation layer and is connected to a water guiding layer, which transports water to the composite photothermal film.
9. The high-salinity wastewater treatment device according to claim 8, characterized in that: The water transport layer and water guiding layer are both non-woven fabric, terry cloth or super absorbent non-woven fabric; the heat insulation layer is one of polystyrene foam, polyurethane foam or polyisocyanate foam; the salt collection layer is a metal plate, glass plate or plastic plate.