Preparation method of CdIn2S4 and InVO4 composite material for promoting photocatalytic degradation of organic dye methylene blue
By synthesizing CdIn2S4 and InVO4 composite materials via a hydrothermal method and constructing a peanut-like structure, the problems of easy recombination of photogenerated electrons and holes and low utilization efficiency of sunlight in photocatalysts were solved, achieving efficient degradation of the organic dye methylene blue and improving the degradation efficiency and stability of the photocatalyst.
Patent Information
- Application Number
- CN202511002027.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-21
- Publication Date
- 2025-11-04
AI Technical Summary
Existing photocatalysts exhibit low degradation efficiency due to the easy recombination of photogenerated electrons and holes when degrading the organic dye methylene blue. Furthermore, they are not efficient at utilizing sunlight, making it difficult to effectively treat wastewater containing high concentrations of organic dyes.
A CdIn2S4 and InVO4 composite material was synthesized by hydrothermal method to construct a unique peanut-shaped structure, which enhances light absorption capacity and separation efficiency of photogenerated carriers. The catalyst dosage and pH value of the reaction system were optimized to improve the photocatalytic degradation efficiency.
The degradation rate of 10 mg·L⁻¹ methylene blue solution reached 90.5% within 180 minutes, which significantly improved the photocatalytic degradation efficiency, extended the service life of the catalyst, and maintained high degradation efficiency at different pH values.
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Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the preparation of a CdIn2S4 and InVO4 composite material, in particular to a preparation method of a CdIn2S4 and InVO4 composite material for promoting photocatalytic degradation of organic dye methylene blue BACKGROUND
[0002] High-concentration organic dye wastewater from many industries such as textiles, leather, plastics, food, medicine and cosmetics is extremely harmful due to its complex composition. Once the wastewater containing highly toxic and chemically resistant organic dyes enters the environment, it will cause extremely serious damage to water bodies, soil and ecosystems.
[0003] Among them, dyes containing N groups such as methylene blue (MB) not only have strong stability to sunlight and are difficult to disappear through natural degradation, but also generate harmful substances with carcinogenicity after degradation under reducing anaerobic conditions, which pose a long-term threat to animals, plants and human health. If such wastewater is directly discharged without proper treatment, it will destroy the ecological balance of water bodies, affect the safety of drinking water, and even accumulate harm to the human body through the food chain. In such a severe environmental situation, some physical and chemical means are needed to degrade methylene blue.
[0004] Existing dye degradation technologies are diverse, but have some shortcomings. Adsorption technology is a common and economical way to remove organic pollutants such as dyes, which uses porous adsorbents to adsorb dye molecules through various forces, but is affected by factors such as initial dye concentration and is difficult to optimize after saturation. Ion exchange method is based on ion exchange membrane, but is easily interfered by other ions in the solution, reducing efficiency, and the membrane needs to be replaced regularly, which is too costly. Chemical precipitation method separates by simply adding chemicals to react with dye molecules to form precipitates, which produces a lot of chemical sludge, and the subsequent treatment cost is high, and part of the precipitation reaction may not be complete, resulting in incomplete removal of dyes. In addition, biological treatment method degrades through biological adsorption and enzyme degradation or a combination of the two, and the growth of microorganisms requires harsh environmental conditions (such as temperature, pH, dissolved oxygen, etc.), and the degradation efficiency will decrease significantly when the environment is not suitable.
[0005] Therefore, photocatalytic degradation technology, as one of the best strategies for efficient use of solar energy to remove organic pollutants, has great development prospects by generating electron-hole pairs through the absorption of light with sufficient energy. These electron-hole pairs will react with water molecules and adsorbed oxygen molecules to generate active substances such as hydroxyl radicals and superoxide radicals with strong oxidizing ability. These radicals can contact and rapidly react with organic pollutants to achieve the degradation goal, thereby realizing water purification treatment. This technology has the advantages of high selectivity, fast reaction speed and simple operation, and has high research value in the field of treatment of refractory pollutants.
[0006] However, the current photocatalyst still faces many challenges in application: first, the photo-generated electron-hole pairs are prone to recombination, and once the recombination rate is too fast, the photo-generated electrons will be difficult to participate in the dye degradation reaction, directly affecting the smooth progress of the degradation process; second, the photocatalyst has low utilization efficiency of sunlight, and can only absorb part of the energy of sunlight, which greatly restricts the improvement of degradation efficiency, so that its efficiency in actual wastewater treatment cannot be fully utilized.
[0007] In the comparative document (Applied Surface Science, 2020, 501, 144006), methylene blue is degraded by modifying InVO4 with ZnFe2O4, and the degradation rate of methylene blue reaches 88.74% in 8h. In the present application, InVO4 is modified with CdIn2S4, and the degradation efficiency is higher, reaching 90.5% in only 180 minutes.
[0008] In the comparative document (Materials Science in Semiconductor Processing, 2024, 175, 108290), ZnIn2S4 is used, and the degradation effect of the composite material is only about 60% in 120 minutes. Compared with the CdIn2S4 composite material of the present application, the degradation can reach 73.47% in 120 minutes and 90.5% in 180 minutes. The materials used in the process are simple and inexpensive, and the prepared CIS-2IVO photocatalyst has better catalytic activity and environmental friendliness.
[0009] Therefore, in view of the shortcomings of the prior art, the present application uses a hydrothermal method to synthesize CdIn2S4 and InVO4 composite material for degrading methylene blue, which improves the light absorption capacity of CIS-2IVO, the separation efficiency of photo-generated carriers, and the degradation efficiency of methylene blue. The photocatalyst is simple to prepare, has low cost, and is conducive to recycling. SUMMARY
[0010] Therefore, the present application provides a preparation method of CdIn2S4 and InVO4 composite material for promoting photocatalytic degradation of organic dye methylene blue.
[0011] To solve the above technical problems, the present application adopts the following technical solutions:
[0012] A preparation method of CdIn2S4 and InVO4 composite material for promoting photocatalytic degradation of organic dye methylene blue, comprising the following steps:
[0013] Step 1: Preparation of InVO4
[0014] Step 1.1: In(NO3)3 is placed in distilled water and stirred vigorously to obtain solution A;
[0015] Step 1.2: NaVO3 was stirred in distilled water to obtain a uniform solution B;
[0016] Step 1.3: The solution B was slowly and uniformly added to the solution A, and the pH value of the mixed solution was adjusted to be acidic by adding nitric acid, ensuring that the pH value was below 2, and the mixed solution was stirred again;
[0017] Step 1.4: The reacted compound was transferred to a high-pressure reaction kettle with a highly specialized polytetrafluoroethylene liner for reaction, centrifugal washing, collection of the precipitate in an oven overnight, and obtaining a light yellow powder named IVO;
[0018] Step 2: Preparation of CdIn2S4 / InVO4
[0019] Step 2.1: 0.230 g, 0.458 g, and 0.689 g of InVO4 were dispersed in water, respectively;
[0020] Step 2.2: CdCl2·5H2O, InCl3·4H2O, and thioacetamide were dissolved in a solution, and the mixed solution was stirred vigorously;
[0021] Step 2.3: The hydrothermal synthesis reaction was carried out in a stainless steel autoclave lined with PTFE, and the obtained CIS-XIVO was washed thoroughly with water and anhydrous ethanol, filtered, and then placed in an oven overnight to obtain the product.
[0022] Preferably, in the step 1.1, the amount of In(NO3)3 is 2.0 mmol, and the amount of distilled water added is 20 mL.
[0023] Preferably, in the step 1.2, the amount of NaVO3 is 2.0 mmol, the amount of distilled water added is 40 mL, and the stirring time is 30 min.
[0024] Preferably, in the step 1.3, the mixed solution is stirred for 1 h again.
[0025] Preferably, in the step 1.4, the reaction temperature in the high-pressure reaction kettle with a highly specialized polytetrafluoroethylene liner is 180°C, the reaction time is 18 h, and the centrifugal washing is performed 6 times.
[0026] Preferably, in the step 2.1, 0.230 g, 0.458 g, and 0.689 g of InVO4 are dispersed in 60 mL of water, respectively.
[0027] Preferably, in the step 2.2, the substance amount of CdCl2·5H2O is 1 mmol, the substance amount of InCl3·4H2O is 2 mmol, and the substance amount of thioacetamide is 4 mmol, and the mixed solution is stirred intensively for 30 min.
[0028] Preferably, in the step 2.3, the volume of the PTFE-lined stainless steel autoclave is 100 mL, the hydrothermal synthesis reaction temperature is 180℃, and the reaction time is 12 h; and the obtained CIS-XIVO is washed with water and anhydrous ethanol for 6 times.
[0029] The present application has the following technical effects relative to the prior art:
[0030] (1) The present application synthesizes InVO4 by hydrothermal reaction, and then modifies the spherical InVO4 on the surface of the spherical CdIn2S4 to successfully construct a unique peanut-shaped CIS-2IVO composite material; not only the operation is simple and controllable, but also the light response range is effectively widened through the innovative design of the material structure, which provides more sufficient light energy for the photocatalytic degradation of methylene blue; and the experimental results show excellent degradation effect in the aspect of catalytic performance;
[0031] (2) The present application optimizes the catalyst dosage and the pH value of the reaction system, and the degradation rate of the composite material to 10 mg·L-1 of methylene blue solution can reach 90.5% within 180 min; in-depth analysis shows that the construction of the peanut-shaped structure is the core reason for the performance improvement, which not only enhances the light absorption capacity of CIS-2IVO, promotes the conversion of light energy to chemical energy, but also significantly improves the separation and migration efficiency of photo-generated carriers, reduces the recombination loss of electron-hole pairs; at the same time, this structure design further enhances the chemical stability of the composite material, effectively inhibits the loss of active components in the reaction process, thereby greatly improving the degradation efficiency while prolonging the service life of the catalyst, which provides a practical and innovative solution for efficient photocatalytic degradation of organic pollutants. BRIEF DESCRIPTION OF DRAWINGS
[0032] Figure 1 The XRD graph of the composite sample of the present application;
[0033] Figure 2 (a-c) are the SEM graphs of CdIn2S4, InVO4 and CIS-2IVO of the present application; (d-e) are the TEM graph and HRTEM graph of CIS-2IVO of the present application; (f-k) are the energy dispersive spectroscopy graphs of CIS-2IVO of the present application;
[0034] Figure 3 (a) is the UV-Vis absorption spectrum of 10 mg·L-1 of methylene blue solution degraded by the catalyst of the present application; -1Figure (a) is a degradation curve of methylene blue; (b) is a first order kinetics curve of the present application; (c) is a kinetic constant distribution graph of the present application; (d) is a degradation curve of methylene blue in the recycling experiment of the present application;
[0035] Figure 4 Figure (a) is a degradation curve of methylene blue by different amounts of catalyst of the present application; (b) is a first order kinetics curve of the present application; (c) is a kinetic constant distribution graph of the present application;
[0036] Figure 5 Figure (a) is a degradation curve of MB at different pH of the present application; (b) is a first order kinetics curve of the present application; (c) is a kinetic constant distribution graph of the present application. DETAILED DESCRIPTION
[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.
[0038] A preparation method of a CdIn2S4 and InVO4 composite material for promoting photocatalytic degradation of organic dye methylene blue, comprising the following steps:
[0039] Step 1: Preparation of InVO4
[0040] Step 1.1: 2.0 mmol of In(NO3)3 was placed in 20 mL of distilled water and stirred vigorously to obtain solution A;
[0041] Step 1.2: 2.0 mmol of NaVO3 was stirred in 40 mL of distilled water for 30 min to obtain a uniform solution B;
[0042] Step 1.3: Solution B was slowly and uniformly added to solution A, and the pH value of the mixed solution was adjusted to be acidic by increasing the concentration of nitric acid, ensuring that the PH was below 2, and the mixed solution was stirred for another 1 h;
[0043] Step 1.4: The reacted compound was transferred to a high-pressure reaction kettle with a highly specialized polytetrafluoroethylene liner, and reacted at 180℃ for 18 h, and then centrifuged and washed 6 times, and the precipitate was collected in an oven overnight to obtain a light yellow powder named IVO;
[0044] Step 2: Preparation of CdIn2S4 / InVO4
[0045] Step 2.1: 0.230 g, 0.458 g, and 0.689 g of InVO4 were respectively dispersed in 60 mL of water;
[0046] Step 2.2: 1 mmol of CdCl2·5H2O, 2 mmol of InCl3·4H2O and 4 mmol of thioacetamide (TAA) were dissolved in solution, and the mixed solution was stirred vigorously for 30 min;
[0047] Step 2.3: The hydrothermal synthesis reaction was transferred to a 100 mL PTFE-lined stainless steel autoclave, the reaction temperature was 180 °C, and the reaction time was 12 h; the obtained CIS-XIVO was washed with water and anhydrous ethanol for 6 times, and then filtered and dried in an oven overnight to obtain the product.
[0048] Example 1: Structure and morphology characterization of MNM composite materials
[0049] The microcrystalline structure of the monomers and their composite materials was analyzed by XRD. The XRD patterns of the prepared samples are shown in Figure 1 For InVO4, the diffraction peaks at 2θ = 18.6°, 20.8°, 31.1°, 33.1° and 35.2° correspond to the (110), (020), (200), (112) and (130) crystal planes of the orthorhombic InVO4 phase (PDF #48-0898), respectively.
[0050] For CdIn2S4, the diffraction peaks at 2θ = 23.2°, 27.2°, 28.5°, 33.1°, 40.8°, 43.3° and 47.4° correspond to the (220), (311), (222), (400), (422), (511) and (440) crystal planes, respectively, indicating that it has a cubic spinel structure (PDF #27-0060).
[0051] No other diffraction peaks were detected in the XRD pattern of the CdIn2S4-InVO4 composite photocatalyst, indicating that the obtained CdIn2S4-InVO4 composite photocatalyst has high purity.
[0052] In addition, it can also be observed that with the increase of InVO4 content, the intensity of the diffraction peaks belonging to the InVO4 phase increases slightly, which also indicates that the CdIn2S4-InVO4 composite photocatalyst has been successfully prepared.
[0053] The morphology of the monomers and composite materials was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and Figure 2 In (a), CdIn2S4 presents a spherical morphology with a diameter of about 5 μm.
[0054] Figure 2 (b) shows that InVO4 is also spherical with a diameter of about 3 μm.
[0055] While the CIS-2IVO composite, as shown in Figure 2 (c) presents a unique peanut shape due to the close contact of the two spheres. This structure not only greatly shortens the transfer path of photo-generated carriers, accelerating the separation of photo-generated carriers, but also has a larger contact area than single material, which can more effectively degrade pollutants.
[0056] Figure 2 (d) further clearly shows the state of the two-sphere contact in the CIS-2IVO composite.
[0057] Through analysis of the high-resolution transmission electron microscopy image of Figure 2 (e), it is measured that the lattice spacing of InVO4 is 0.19 nm and the lattice spacing of CdIn2S4 is 0.30 nm, which indicates that the two substances have successfully achieved composite.
[0058] Energy dispersive spectroscopy (EDS) analysis, as shown in Figure 2 (f-k), shows that there are In, O, Cd, S, V elements in the CIS-2IVO composite, and the close contact state of the two spheres can be observed, which further confirms that the two substances have successfully achieved composite.
[0059] Example 2: Performance of CIS-2IVO composite in degrading methylene blue
[0060] To evaluate the performance of the CIS-2IVO photocatalyst, a 300W xenon lamp with a cutoff filter (λ≥420nm) was used as the visible light source, and methylene blue was used as the degradation object.
[0061] The specific steps are as follows:
[0062] Methylene blue simulated dye wastewater with a concentration of 10mg / L and a pH value of 7.0 was prepared, 100mL of the simulated wastewater was taken and placed in a 200mL reactor, and 30mg of photocatalyst was added. The experiment was carried out at room temperature.
[0063] First, the solution was stirred in the dark environment for 60min to achieve adsorption equilibrium;
[0064] Subsequently, the photocatalytic reaction was carried out under the irradiation of a 300W xenon lamp and a 420nm cutoff filter, and the reaction time was 3 hours. The sample was taken every 30min;
[0065] After sampling, the sample was first filtered using a 0.45μm syringe filter to remove the catalyst, and then the concentration of the remaining methylene blue pollutants in the filtered solution was analyzed by a UV-visible spectrophotometer (detection wavelength λ=664nm) to evaluate the photocatalytic effect;
[0066] As a preferred embodiment of the present application, the degradation rate of methylene blue is calculated according to the following formula:
[0067] D(%) = [(C0-C t ) / C0]x100%
[0068] Wherein, C0 is the initial concentration of methylene blue, C t is the concentration of methylene blue after degradation.
[0069] Next, we respectively carried out photocatalytic degradation on CdIn2S4, InVO4 and their composite materials in different proportions.
[0070] As shown in Figure 3 (a), almost all the materials have no degradation effect in 0-60 minutes of darkness, indicating that the material degradation depends on photocatalysis, excluding physical adsorption. CdIn2S4 has a degradation effect of only 52.5% after 180 minutes of light, and InVO4 also only reaches 60.9% after 180 minutes of light, with poor degradation effect.
[0071] We carried out photocatalytic degradation on modified CIS-IVO, CIS-2IVO and CIS-3IVO, and the degradation effect was greatly improved, being 68.9%, 90.5% and 75.6% respectively, all better than unmodified IVO and CIS.
[0072] And CIS-2IVO shows the best performance, which may be due to too little IVO providing fewer active sites, and too much IVO may accelerate the recombination of photo-generated electrons and holes.
[0073] Next, the degradation kinetics was studied, and a first-order kinetics straight line was obtained.
[0074] As shown in Figure 3 (b), the straight line slope of CIS-2IVO is the largest, also indicating that it has the best degradation effect.
[0075] As shown in Figure 3 (c), the photocatalytic rate constant k of each material is shown, and the value of CIS-2IVO is the largest, indicating that the photocatalytic degradation of pollutants is the fastest.
[0076] In addition, the stability of the composite material was also tested, as shown in Figure 3 (d), after five cycles, the degradation effect of CIS-2IVO can still reach 82.3%, only decreasing by about 8%, so this catalyst has stable photocatalytic effect.
[0077] Next, the effect of different amounts of CIS-2IVO composite catalyst on the degradation performance of MB solution was studied.
[0078] From Figure 4 (a) can be found that 10 mg dosage curve deceleration, attributed to it provides less active site; while 50 mg excess catalyst particles may be agglomeration phenomenon, originally dispersed catalyst particles gathered together. 20-40 mg catalyst degradation decreased faster, 180 minutes degradation effect was 86.0%, 90.5% and 85.7%, and 30 mg had the highest degradation efficiency, indicating that the appropriate amount of catalyst to improve efficiency.
[0079] From Figure 4 (b) can be seen CIS-2IVO composite composite first-order kinetics;
[0080] From Figure 4 (c) derived catalyst dosage of 30 mg of the largest kinetic constant, 0.01264 min -1 , respectively, 2.38 times and 3.90 times the catalyst dosage of 10 mg and 50 mg.
[0081] Finally concluded that 30 mg catalyst is most conducive to degradation of 10 mg·L -1 methylene blue.
[0082] Further explore the adsorption and degradation effect of CIS-2IVO under different pH, pH will affect the catalyst surface charge properties and adsorption capacity.
[0083] As Figure 5 (a) shown, 30 mg of CIS-2IVO catalyst added to 100 mL concentration of 10 mg·L -1 MB solution, when the initial pH value of the solution in turn 3, 5, 7, 9, 11, CIS-2IVO photocatalytic degradation of MB efficiency was 47.2%, 65.7%, 90.5%, 98.9% and 99.6%, in pH = 11, the degradation rate of 10 mg·L -1 MB reached a peak, while in acidic conditions, the degradation effect decreased greatly. This is because the MB in solution is in the form of positive ions. When the solution is acidic, the catalyst surface will adsorb H + in water, so that it is positively charged, so as to produce electrostatic repulsion with MB positive ions, not conducive to the catalyst to adsorb pollutants, degradation efficiency decreased; and when the solution is alkaline, the catalyst surface is negatively charged, with the help of electrostatic adsorption, can enhance the adsorption of pollutants, improve the degradation effect, so after the light 60 minutes CIS-2IVO can be good effect on MB degradation.
[0084] Subsequent degradation kinetics research, such as Figure 5 (b) kinetics fitting and as Figure 5The rate constant of (c) also indicates that the degradation efficiency is the highest at pH = 11, which is consistent with the above conclusion.
[0085] The above is only the preferred embodiment of the present application, and does not limit the technical scope of the present application in any way. Any slight modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still falls within the scope of the technical solution of the present application.
Claims
1. A method for preparing a CdIn2S4 and InVO4 composite material to promote the photocatalytic degradation of the organic dye methylene blue, characterized in that, Includes the following steps: Step 1: Preparation of InVO4 Step 1.1: Place In(NO3)3 in distilled water and stir vigorously to obtain solution A; Step 1.2: Stir NaVO3 in distilled water to obtain a homogeneous solution B; Step 1.3: Slowly and uniformly add solution B to solution A, and adjust the pH of the above mixed solution to acidic by adding nitric acid to ensure that the pH is below 2. Then stir the mixed solution. Step 1.4: The reacted compound was transferred to a high-pressure reactor with a highly specialized polytetrafluoroethylene liner for further reaction. After centrifugation and washing, the precipitate was collected and dried in an oven overnight to obtain a pale yellow powder, which was named IVO. Step 2: Preparation of CdIn2S4 / InVO4 Step 2.1: Disperse 0.230g, 0.458g, and 0.689g of InVO4 in water, respectively; Step 2.2: Dissolve CdCl2·5H2O, InCl3·4H2O and thioacetamide in a solution, and stir the mixture vigorously; Step 2.3: Transfer to a stainless steel autoclave lined with PTFE for hydrothermal synthesis reaction. Wash the obtained CIS-XIVO thoroughly with water and anhydrous ethanol (X is usually omitted when it is 1), filter, and dry in an oven overnight to obtain the product.
2. The method for preparing a CdIn2S4 and InVO4 composite material for promoting the photocatalytic degradation of the organic dye methylene blue according to claim 1, characterized in that, In step 1.1, the amount of In(NO3)3 is 2.0 mmol, and the amount of distilled water added is 20 mL.
3. The method for preparing a CdIn2S4 and InVO4 composite material for promoting the photocatalytic degradation of the organic dye methylene blue according to claim 1, characterized in that, In step 1.2, the amount of NaVO3 is 2.0 mmol, the amount of distilled water added is 40 mL, and the stirring time is 30 min.
4. The method for preparing a CdIn2S4 and InVO4 composite material for promoting the photocatalytic degradation of the organic dye methylene blue according to claim 1, characterized in that, In step 1.3, the mixed solution is stirred for another 1 hour.
5. The method for preparing a CdIn2S4 and InVO4 composite material for promoting the photocatalytic degradation of the organic dye methylene blue according to claim 1, characterized in that, In step 1.4, the reaction temperature in the high-pressure reactor with a highly specialized polytetrafluoroethylene liner is 180°C, the reaction time is 18 hours, and the reactor is centrifuged and washed 6 times.
6. The method for preparing a CdIn2S4 and InVO4 composite material for promoting the photocatalytic degradation of the organic dye methylene blue according to claim 1, characterized in that, In step 2.1, 0.230g, 0.458g, and 0.689g of InVO4 are dispersed in 60mL of water, respectively.
7. The method for preparing a CdIn2S4 and InVO4 composite material for promoting the photocatalytic degradation of the organic dye methylene blue according to claim 1, characterized in that, In step 2.2, the amount of CdCl2·5H2O is 1 mmol, the amount of InCl3·4H2O is 2 mmol, the amount of thioacetamide is 4 mmol, and the mixed solution is stirred vigorously for 30 min.
8. The method for preparing a CdIn2S4 and InVO4 composite material for promoting the photocatalytic degradation of the organic dye methylene blue according to claim 1, characterized in that, In step 2.3, the stainless steel autoclave lined with PTFE has a volume of 100 mL, the hydrothermal synthesis reaction temperature is 180 °C, and the reaction time is 12 h; the obtained CIS-XIVO is thoroughly washed 6 times with water and anhydrous ethanol.