Preparation method and application of C3N4 / WO3 composite material
The C3N4/WO3 composite material addresses the inefficiencies of existing textile recycling methods by enhancing photocatalytic efficiency and stability, enabling efficient and sustainable degradation of polyester fibers with reduced chemical use.
Patent Information
- Application Number
- CN202510461823.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-14
- Publication Date
- 2025-07-15
AI Technical Summary
When handling waste textiles, the physical recycled polyester is not of high quality, it is difficult to completely separate fibers, and the equipment investment is high, while the chemical law is harsh and the pollution is high, and there is a lack of efficient and environmentally friendly recycling methods.
C3N4/WO3 composite materials are used as photocatalysts to prepare C3N4/WO3 composite materials by calcining melamine and Na2WO3·2H2O, and combined with photocatalysis and hydrothermal treatment to degrade waste polyester fibers.
It reduces the use of chemical reagents, improves photocatalytic efficiency, enhances active sites, achieves efficient and stable fiber degradation, and reduces pollution and costs.
Smart Images
Figure CN120306002A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of photocatalysts, and particularly relates to a preparation method and application of a C3N4 / WO3 composite material. Background Art
[0002] Common treatment methods include physical methods and chemical methods. The physical method, also known as the mechanical method, refers to decomposing or pulverizing textiles through physical and mechanical means such as sorting, purification, and classification, and then recycling and utilization. The physical method is a simple physical form transformation without changing its composition and chemical components, and has advantages such as low price and simple operation. Natural fiber textiles such as cotton, linen, silk, and wool are mainly recycled by physical methods. In addition, due to the current huge stock and difficult recycling of waste textiles in the world, the physical method has become a relatively fast method for treating waste blended fibers at present. However, this method has several fatal drawbacks: ① The quality of recycled polyester is not high. Many research scholars have studied the post-modification process of recycled polyester. Currently, the research mainly focuses on the chain extension and viscosity increase process of recycled polyester fibers. For example, Shi Yonggang et al. found that bis-2-oxazoline compound-extended PET improved thermal stability and hydrolysis resistance, and enhanced the mechanical properties of glass fiber-reinforced PET; Pandey et al. studied three chain extenders, namely ethyl pyrrole dicarboxylate (PMDA), ethylene carbonate (EC), and polymer epoxide, to improve the properties of melt-extruded recycled polyethylene terephthalate (r-PET); ② The practicality of blended textiles is not strong. It is difficult for physical methods to completely separate different types of fibers, resulting in a decrease in the proportion of recycled materials and affecting the value of circular reuse; ③ Physical separation technologies (such as water washing, air flow separation, etc.) often require high equipment investment and energy consumption, increasing the overall treatment cost.
[0003] The chemical method refers to the chemical composition of textiles, mainly converting polymers into small molecules. These small molecules can either be recycled into the original polymer materials or upgraded into raw materials for alternative chemical materials. Compared with physical methods, the chemical method has relatively higher economic benefits and can maintain the quality of products. Currently, taking PET polyester fiber as an example (with the largest market share), common chemical recycling methods include: ① Hydrolysis to recycle PET to produce ethylene glycol and terephthalic acid (TPA). The reaction is usually carried out at a temperature of 200 - 250°C and a pressure of 1.4 - 2 Mpa, and the reaction is generally completed in 3 - 5 hours. Hydrolysis includes acidic hydrolysis, neutral hydrolysis, and alkaline hydrolysis. Neutral hydrolysis often requires higher temperature and greater pressure; ② Alcoholysis to recycle PET. Alcoholysis generally includes methanol alcoholysis, ethylene glycol alcoholysis, and polyol alcoholysis. Methanol alcoholysis of PET produces dimethyl terephthalate (DMT) at a temperature of 180 - 280°C and a pressure of 1.7 - 3 MPa; Ethylene glycol alcoholysis of PET produces bis(2-hydroxyethyl) terephthalate (BHET). The depolymerization of this method is usually carried out at a temperature of 180 - 250°C and a pressure of 0.1 - 0.6 Mpa. In the chemical recycling process of PET, there is currently a lot of research on ethylene glycol alcoholysis of PET, but there are problems such as low conversion efficiency and difficulty in decolorizing the product during ethylene glycol alcoholysis; ③ Ammonolysis to recycle PET to produce bis(2-hydroxyethyl) terephthalamine (BHETA), usually carried out with an aqueous solution of primary amine. There is less exploration of this method in PET recycling. During ammonolysis, the aqueous solutions commonly used for depolymerizing PET include methylamine, ethylamine, etc. Currently, most chemical methods for treating waste textiles are carried out under high temperature and high pressure conditions. The reaction conditions are relatively harsh, requiring relatively high equipment requirements and causing relatively large environmental pollution. Therefore, to efficiently and environmentally treat and recycle waste textiles, we need to find a pollutant treatment technology with low cost, high efficiency, and high greenness, and obtain the polyester fiber monomer terephthalic acid to achieve the recycling of waste fibers. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a preparation method and application of a C3N4 / WO3 composite material in view of the deficiencies of the above-mentioned prior art. This preparation method can reduce the use of chemical reagents, improve the photocatalytic efficiency using the C3N4 / WO3 composite material as a photocatalyst, and has stability and reusability.
[0005] To solve the above technical problem, the technical solution adopted by the present invention is: A preparation method of a C3N4 / WO3 composite material, and the method is as follows:
[0006] S1. Prepare a C3N4 catalyst:
[0007] After grinding melamine, it is calcined at a temperature of 500°C to 600°C for 1h to 3h, cooled naturally, ground, then calcined at a temperature of 500°C to 600°C for 1h to 3h, cooled naturally to room temperature, and ground to obtain C3N4 powder;
[0008] S2. Preparation of C3N4 / WO3 composite material:
[0009] Dissolve Na2WO3·2H2O in water, stir and mix for 10 min to 30 min, then add lactic acid and continue to stir for 10 min to 30 min to obtain a light yellow solution. Add the C3N4 powder obtained in S1, stir for 10 min to 30 min, then perform ultrasonic assisted oscillation for 10 min to 30 min, and then dropwise add a hydrochloric acid solution with a concentration of 1 mol / L to 3 mol / L to adjust the pH of the system to 1 and stir for 10 min to 30 min. Heat the obtained mixed solution at a temperature of 150°C to 200°C for 12h to 24h, cool naturally to room temperature, wash alternately with deionized water and ethanol 3 times, and dry to obtain the C3N4 / WO3 composite material, which is the photocatalyst for degrading waste polyester fiber.
[0010] Preferably, the average particle size of the C3N4 powder in S1 is 500 nm to 600 nm.
[0011] Preferably, the dosage ratio of Na2WO3·2H2O, water, lactic acid and C3N4 powder in S2 is (1 - 2) g : (50 - 100) mL : (1 - 2) mL : (0.1 - 0.5) g.
[0012] The present invention also provides the application of the photocatalyst for degrading waste polyester fiber prepared by the above preparation method. The C3N4 / WO3 composite material is used as a photocatalyst for degrading waste polyester fiber.
[0013] Preferably, the method for using the C3N4 / WO3 composite material to degrade waste polyester fiber is as follows:
[0014] Add water to the waste polyester fiber, perform hydrothermal treatment at a temperature of 150°C to 200°C for 5h to 12h, cool naturally to room temperature, rinse with clean water, and dry to obtain pretreated polyester fiber;
[0015] Add the C3N4 / WO3 composite material and water to the pretreated polyester fiber, and perform photocatalytic reaction at room temperature and under a 500w xenon lamp for 5h to 12h.
[0016] Preferably, the mass ratio of the waste polyester fiber to the C3N4 / WO3 composite material is 1:1.
[0017] Preferably, the C3N4 / WO3 composite material can also be combined with potassium monopersulfate for the degradation of waste polyester fibers.
[0018] The present invention has the following advantages compared with the prior art:
[0019] 1. The preparation method of the C3N4 / WO3 composite material of the present invention can reduce the use of chemical reagents: Compared with some traditional chemical treatment methods, photocatalysis mainly relies on photocatalysts and clean energy such as sunlight to drive reactions. There is no need to use a large amount of corrosive chemical reagents such as strong acids and strong alkalis, reducing the generation of chemical waste and the subsequent treatment cost, and further reducing the threat of chemical pollution to the ecological environment.
[0020] 2. The photocatalytic efficiency of the C3N4 / WO3 composite material prepared by the present invention is improved: Using the C3N4 / WO3 composite material as a photocatalyst, C3N4 and WO3 form a Z-type heterojunction, realizing efficient separation and migration of photo-generated carriers. At the same time, combining the advantages of C3N4 and WO3, the number of active sites increases, the light response range is improved, and compared with common photocatalysts, the degradation rate of polyester fiber (PET) is increased and the weight loss rate is increased.
[0021] 3. The C3N4 / WO3 composite material prepared by the present invention has stability and reusability as a photocatalyst: This composite material has good chemical stability. During multiple photocatalytic cycles, the structure is not easily damaged and the catalytic performance remains basically stable. This means that the photocatalyst can be reused multiple times, reducing the cost increase caused by frequent catalyst replacement, and further optimizing the economy and sustainability of the entire treatment process.
[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings
[0023] Figure 1 is the SEM image of the untreated polyester fiber in Example 1 of the present invention.
[0024] Figure 2 is the SEM image (a) of the polyester fiber pretreated at 180 °C for 12 h and the SEM image (b) of the polyester fiber after photocatalysis in Example 1 of the present invention.
[0025] Figure 3 is the thermogravimetric (TG) analysis curve of the polyester fiber in Example 1 of the present invention.
[0026] Figure 4 is the weight loss rate after the photocatalytic degradation of the polyester fiber by the C3N4 / WO3 composite material prepared in Example 1 of the present invention.
[0027] Figure 5It is the weight loss rate after the photocatalytic degradation of polyester fiber by the C3N4 / WO3 composite material prepared in Example 2 of the present invention.
[0028] Figure 6 It is the weight loss rate after the photocatalytic degradation of polyester fiber by the C3N4 / WO3 composite material prepared in Example 3 of the present invention.
[0029] Figure 7 It is the liquid chromatogram of terephthalic acid after the photocatalytic degradation of polyester fiber by the C3N4 / WO3 composite material prepared in Example 3 of the present invention. Detailed implementation manners
[0030] Example 1
[0031] The preparation method of the C3N4 / WO3 composite material in this example is as follows:
[0032] S1. Prepare the C3N4 catalyst:
[0033] After grinding melamine, it is calcined at 600 °C for 1 h, naturally cooled, ground, then calcined at 600 °C for 1 h, naturally cooled to room temperature, and ground to obtain C3N4 powder with an average particle size of 500 nm.
[0034] S2. C3N4 / WO3 composite material:
[0035] Dissolve 1 g of Na2WO3·2H2O in 50 mL of water, stir and mix for 10 min, then add 1 mL of lactic acid and continue to stir for 10 min to obtain a light yellow solution. Add 0.1 g of the C3N4 powder obtained in S1, stir for 10 min, then ultrasonically assist and oscillate for 10 min, then dropwise add 1 mol / L hydrochloric acid solution to adjust the pH of the system to 1, and stir for 10 min. Heat the obtained mixed solution at 150 °C for 24 h, naturally cool to room temperature, wash it 3 times alternately with deionized water and ethanol, and dry it to obtain the C3N4 / WO3 composite material, which is the photocatalyst for degrading waste polyester fiber.
[0036] The present invention also provides the application of the photocatalyst for degrading waste polyester fiber prepared by the above preparation method. The C3N4 / WO3 composite material is used as a photocatalyst for degrading waste polyester fiber.
[0037] The method for using the C3N4 / WO3 composite material to degrade waste polyester fiber is as follows:
[0038] Add water to the waste polyester fiber, perform hydrothermal treatment at 180 °C for 12 h, naturally cool to room temperature, rinse with clean water, and dry to obtain the pretreated polyester fiber.
[0039] 200 mg of the pretreated polyester fiber was added with 200 mg of the C3N4 / WO3 composite material and 50 mL of water, and a photocatalytic reaction was carried out for 12 h under the conditions of room temperature and a 500-w xenon lamp.
[0040] The C3N4 / WO3 composite material can also be combined with potassium monopersulfate to degrade waste polyester fiber.
[0041] As Figure 1 shown, the original SEM image of the untreated polyester fiber has a smooth and flat surface. Figure 2 a is the morphology image of the polyester fiber treated at 180 °C. Compared with the morphology before treatment ( Figure 1 ), the surface becomes rougher and the contact area is wider. Figure 2 b is the morphology image after photocatalysis. Some catalysts are attached to the surface, and at the same time, some corroded or reacted parts appear.
[0042] At the same time, thermogravimetric analysis was carried out on the polyester fiber. Figure 3 It was found that the polyester fiber began to lose weight at 350-400 °C. Therefore, no decomposition, volatilization or other chemical reactions occurred during the pretreatment at 180 °C. Using the C3N4 / WO3 composite material prepared in this example for photocatalytic reaction, as Figure 4 shown, in the figure:
[0043] ① cat + PET: represents 200 mg of the 0.1 C3N4 / WO3 composite material prepared in this example + 200 mg of the pretreated polyester fiber (PET); where 0.1 in the 0.1 C3N4 / WO3 composite material represents that the amount of C3N4 added during the preparation of C3N4 / WO3 is 0.1 g.
[0044] ② cat + PET + PMS: represents 200 mg of the C3N4 / WO3 composite material prepared in this example + 200 mg of the pretreated polyester fiber + 3 mM of potassium monopersulfate (PMS);
[0045] ③ CN + PET: represents 200 mg of the C3N4 powder (CN) prepared in step S1 of this example + 200 mg of the pretreated polyester fiber;
[0046] ④ WO represents WO3.
[0047] The preparation method of WO3 is as follows: Dissolve 1 g of Na2WO3·2H2O in 50 mL of water, stir and mix for 10 min, then add 1 mL of lactic acid and continue stirring for 10 min to obtain a pale yellow solution. Then, add 1 mol / L hydrochloric acid solution dropwise to adjust the pH of the system to 1, and stir for 10 min. Hydrothermally heat the obtained mixed solution at 150 °C for 24 h. After naturally cooling to room temperature, wash it alternately with deionized water and ethanol 3 times, and then dry it to obtain WO3.
[0048] As Figure 4 shown, in the photocatalytic experiment under the conditions of 12 h and 500 w, when PMS, C3N4 (CN in the figure), and WO3 (WO in the figure) are added alone, the weight loss rates reach 16.66%, 14.64%, and 22.15% respectively; when the C3N4 / WO3 composite material is added, the weight loss rate is increased to 43.14% because a heterojunction is formed between C3N4 and WO3, enabling more efficient separation and migration of photo-generated carriers, and at the same time proving that the C3N4 / WO3 composite material has good photocatalytic performance; when PMS and the C3N4 / WO3 composite material are added simultaneously, the weight loss rate reaches 67.15% because more sulfate radicals (·SO4 - ) are generated after adding PMS. The entire photocatalytic process depends on active groups such as ·SO4 - , ·O 2- and ·OH to play a key role. Therefore, the C3N4 / WO3 composite material in this example can also be combined with potassium peroxymonosulfate for the degradation of waste polyester fibers.
[0049] The preparation method of the C3N4 / WO3 composite material in this example can reduce the use of chemical reagents: Compared with some traditional chemical treatment methods, photocatalysis mainly relies on photocatalysts and clean energy such as sunlight to drive reactions. There is no need to use a large amount of corrosive chemical reagents such as strong acids and strong bases, reducing the generation of chemical waste and the subsequent treatment cost, and further reducing the threat of chemical pollution to the ecological environment.
[0050] The photocatalytic efficiency of the C3N4 / WO3 composite material prepared in this example is improved: Using the C3N4 / WO3 composite material as a photocatalyst, a Z-type heterojunction is formed between C3N4 and WO3 to achieve efficient separation and migration of photo-generated carriers. At the same time, by combining the advantages of C3N4 and WO3, the number of active sites increases, the light response range is improved, and compared with common photocatalysts, the degradation rate of polyester fiber (PET) is increased and the weight loss rate is increased.
[0051] The C3N4 / WO3 composite material prepared in this example has stability and reusability as a photocatalyst: this composite material has good chemical stability, and during multiple photocatalytic cycles, its structure is not easily damaged, and the catalytic performance remains basically stable. This means that the photocatalyst can be reused multiple times, reducing the cost increase caused by frequent catalyst replacement, and further optimizing the economy and sustainability of the entire treatment process.
[0052] Example 2
[0053] The preparation method of the C3N4 / WO3 composite material in this example is as follows:
[0054] S1. Prepare the C3N4 catalyst:
[0055] After grinding melamine, it is calcined at 500 °C for 3 h, naturally cooled, ground, then calcined at 500 °C for 3 h, naturally cooled to room temperature, and after grinding, C3N4 powder with an average particle size of 500 nm is obtained;
[0056] S2. Prepare the WO3 material:
[0057] Dissolve 2 g of Na2WO3·2H2O in 100 mL of water, stir and mix for 30 min, then add 2 mL of lactic acid and continue to stir for 30 min to obtain a light yellow solution. Add 0.5 g of the C3N4 powder obtained in S1, stir for 30 min, then perform ultrasonic assisted oscillation for 30 min, then dropwise add 3 mol / L hydrochloric acid solution to adjust the pH of the system to 1, and stir for 30 min. Heat the obtained mixed solution at 200 °C for 12 h, naturally cool to room temperature, wash it alternately with deionized water and ethanol 3 times, and after drying, obtain the C3N4 / WO3 composite material, which is the photocatalyst for degrading waste polyester fibers.
[0058] The present invention also provides the application of the photocatalyst for degrading waste polyester fibers prepared by the above preparation method. The C3N4 / WO3 composite material is used as a photocatalyst for degrading waste polyester fibers.
[0059] The method for using the C3N4 / WO3 composite material to degrade waste polyester fibers is as follows:
[0060] Add water to waste polyester fibers, perform hydrothermal treatment at 200 °C for 5 h, naturally cool to room temperature, rinse with clean water, and dry to obtain pretreated polyester fibers;
[0061] Add 200 mg of the pretreated polyester fibers, 200 mg of the C3N4 / WO3 composite material, and 50 mL of water, and perform photocatalytic reaction at room temperature under a 500 w xenon lamp for 5 h.
[0062] As Figure 5 shown, in the photocatalytic experiment under the conditions of 12 h and 500 w, when 200 mg of C3N4 ( Figure 5 CN in Figure 5 ), 200 mg of WO3 ( Figure 5 WO in
[0063] ), and 200 mg of 0.5C3N4 / WO3 (
[0064] 0.5CNWO in
[0065] ) were added separately, the weight loss rates reached 15.50%, 18.91%, and 22.77% respectively.
[0066] Among them, 0.5 in 0.5CNWO means that the amount of C3N4 added during the preparation of C3N4 / WO3 is 0.5 g.
[0067] After grinding melamine, it was calcined at 550 °C for 2 h, cooled naturally, ground, then calcined at 550 °C for 2 h, cooled naturally to room temperature, and ground to obtain C3N4 powder with an average particle size of 550 nm;
[0068] S2. Preparation of WO3 material:
[0069] 1 g of Na2WO3·2H2O was dissolved in 100 mL of water, stirred and mixed for 20 min, then 1 mL of lactic acid was added and stirred for another 20 min to obtain a light yellow solution. 0.3 g of the C3N4 powder obtained in S1 was added, stirred for 20 min, then ultrasonically assisted and oscillated for 20 min, and then a 2 mol / L hydrochloric acid solution was added dropwise to adjust the pH of the system to 1 and stirred for 20 min. The obtained mixed solution was heated at 180 °C for 20 h, cooled naturally to room temperature, washed 3 times alternately with deionized water and ethanol, and dried to obtain the C3N4 / WO3 composite material, which is the photocatalyst for degrading waste polyester fiber.
[0070] The present invention also provides the application of the photocatalyst for degrading waste polyester fiber prepared by the above preparation method. The C3N4 / WO3 composite material is used as a photocatalyst for degrading waste polyester fiber.
[0071] The method for using the C3N4 / WO3 composite material to degrade waste polyester fiber is as follows:
[0072] Water is added to waste polyester fiber, and it is hydrothermally treated at 150 °C for 12 h. After naturally cooling to room temperature, it is rinsed with clean water and then dried to obtain pretreated polyester fiber.
[0073] 200 mg of the pretreated polyester fiber, 200 mg of the C3N4 / WO3 composite material and 50 mL of water are added, and a photocatalytic reaction is carried out for 12 h at room temperature under a 500 w xenon lamp.
[0074] As Figure 6 shown, in the photocatalytic experiment under the conditions of 12 h and 500 w, when 200 mg of C3N4 ( Figure 6 CN in it), 200 mg of WO3 ( Figure 6 WO in it) and 200 mg of 0.3C3N4 / WO3 ( Figure 6 0.3CNWO in it) are added separately, the weight loss rates reach 12.90%, 14.90% and 30.00% respectively.
[0075] Among them, 0.3 in 0.3CNWO means that the amount of C3N4 added in the preparation of C3N4 / WO3 is 0.3 g.
[0076] As Figure 7 shown, after the photocatalytic reaction is completed, the collected water sample is detected. The liquid chromatography result shows terephthalic acid, the monomer of polyester fiber after the photocatalytic reaction. The PET depolymerization rate is 30% - 45%. The obtained terephthalic acid can be used to prepare fiber products, realizing the recycling of waste fibers.
[0077] The above is only a preferred embodiment of the present invention and does not impose any limitation on the present invention. Any simple modification, change and equivalent change made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.
Claims
1. A method for preparing a C3N4 / WO3 composite material, characterized in that, The method is as follows: S1. Prepare the C3N4 catalyst: After grinding melamine, calcine it for 1 h - 3 h under the condition of a temperature of 500°C - 600°C, cool it naturally, grind it, then calcine it for 1 h - 3 h under the condition of a temperature of 500°C - 600°C, cool it naturally to room temperature, and after grinding, obtain C3N4 powder; S2. Prepare the C3N4 / WO3 composite material: Dissolve Na2WO3·2H2O in water, stir and mix for 10 min - 30 min, then add lactic acid and continue to stir for 10 min - 30 min to obtain a light yellow solution. Add the C3N4 powder obtained in S1, stir for 10 min - 30 min, then perform ultrasonic-assisted oscillation for 10 min - 30 min, then dropwise add a hydrochloric acid solution with a concentration of 1 mol / L - 3 mol / L to adjust the pH of the system to 1, and stir for 10 min - 30 min. Heat the obtained mixed solution at a temperature of 150°C - 200°C for 12 h - 24 h, cool it naturally to room temperature, wash it alternately with deionized water and ethanol 3 times, and after drying, obtain the C3N4 / WO3 composite material.
2. The preparation method of a C3N4 / WO3 composite material according to claim 1, characterized in that, The average particle size of the C3N4 powder described in S1 is 500 nm - 600 nm.
3. The preparation method of a C3N4 / WO3 composite material according to claim 1, characterized in that, The dosage ratio of Na2WO3·2H2O, water, lactic acid and C3N4 powder described in S2 is (1 - 2) g : (50 - 100) mL : (1 - 2) mL : (0.1 - 0.5) g.
4. Use of a C3N4 / WO3 composite material prepared by the preparation method according to any one of claims 1-3, characterized in that, The C3N4 / WO3 composite material is used as a photocatalyst for degrading waste polyester fibers.
5. The application according to claim 4, wherein The method for using the C3N4 / WO3 composite material to degrade waste polyester fibers is as follows: Add water to the waste polyester fibers, perform hydrothermal treatment at a temperature of 150°C - 200°C for 5 h - 12 h, cool it naturally to room temperature, rinse it with clean water, and dry it to obtain pretreated polyester fibers; Add the C3N4 / WO3 composite material and water to the pretreated polyester fibers, and perform a photocatalytic reaction at room temperature under a 500 w xenon lamp for 5 h - 12 h.
6. The application according to claim 5, characterized in that, The mass ratio of the waste polyester fibers to the C3N4 / WO3 composite material is 1:
1.
7. The application according to claim 4, wherein The C3N4 / WO3 composite material can also be combined with potassium peroxymonosulfate to degrade waste polyester fibers.