Preparation method and application of a non-iron-based heterogeneous fenton-like catalyst

Abstract

The application discloses a preparation method of a non-iron-based heterogeneous Fenton-like catalyst, which comprises the following steps: adding copper nitrate trihydrate and m-benzenetricarboxylic acid into an ethanol-water mixed solution in sequence, uniformly mixing, and then carrying out a hydrothermal reaction at 80-140 DEG C; performing solid-liquid separation, washing and drying the solid to obtain a solid product; dispersing the solid product in a methanol solution containing cobalt nitrate, adding a methanol solution containing 2-methyl imidazole, stirring for 10-15 hours, then standing for 10-15 hours, performing solid-liquid separation, washing and drying the solid to obtain the non-iron-based heterogeneous Fenton-like catalyst; and applying the prepared catalyst to the treatment of dye wastewater, wherein the experimental results show that the catalyst can effectively remove methylene blue in the wastewater, and the application provides a new way for the treatment of industrial dye wastewater.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a non-iron-based heterogeneous Fenton-like catalyst and application thereof in treatment of dye wastewater. BACKGROUND

[0002] At present, a large amount of wastewater containing refractory organic pollutants is easily generated in papermaking, textile, pharmaceutical and printing industries, and the wastewater contains complex components, has high concentration, poor biodegradability, and is toxic and carcinogenic, which poses a great threat to the ecological environment and human health.

[0003] So far, the methods for treating organic pollutants in wastewater include adsorption, photocatalysis, membrane separation, advanced oxidation, etc. Among these methods, the advanced oxidation method has been proved to be efficient in treating organic pollutants in wastewater in a short time, and has great potential in dye wastewater treatment, especially the heterogeneous Fenton / Fenton-like technology, which is widely used due to its mild operating conditions, low preparation cost and simple operation. Research shows that the heterogeneous Fenton-like catalysis can effectively solve the bottleneck problem existing in the traditional Fenton technology. In the past few decades, many heterogeneous catalytic materials, such as metal oxides, clays, zeolites, graphene oxides, carbon materials, metal organic frameworks (MOFs), etc., have been widely used in Fenton-like degradation. Among the numerous catalysts, MOFs constructed by metal nodes and organic ligands are a kind of periodic porous materials with great application potential in catalytic Fenton-like reaction, because they have the advantages of large specific surface area, adjustable pore size and strong adsorption performance. To our knowledge, most of the MOFs catalytic Fenton-like reactions are focused on Fe-based MOFs. However, iron is easily precipitated under alkaline conditions, which greatly limits its large-scale application in industry.

[0004] HKUST-1 is a Cu-MOF material, which can easily generate Cu 2+ / Cu + mixed metal ions under acid coordination, but the serious agglomeration problem and limited electron transfer capacity greatly hinder its application in dye wastewater degradation, and it shows poor Fenton-like degradation performance. SUMMARY

[0005] The application provides a preparation method of a non-iron-based heterogeneous Fenton-like catalyst, which comprises the following steps: sequentially adding copper nitrate trihydrate and trimesic acid into an ethanol-water mixed solution, uniformly mixing, and then performing hydrothermal reaction at 80-140 DEG C; performing solid-liquid separation, washing and drying the solid to obtain a solid product; dispersing the solid product in a methanol solution containing cobalt nitrate, adding a methanol solution containing 2-methylimidazole, stirring for 10-15 hours, then standing for 10-15 hours, performing solid-liquid separation, washing and drying the solid to obtain the non-iron-based heterogeneous Fenton-like catalyst.

[0006] The molar ratio of the copper nitrate trihydrate and the trimesic acid is 1.5-2:1, the ethanol-water mixed solution is prepared by mixing ethanol and water in a volume ratio of 1-2:1; the mass ratio of the solid product to the cobalt nitrate is 0.1-0.5:1, and the molar ratio of the cobalt nitrate to the 2-methylimidazole is 1:4-8.

[0007] Another object of the present application is to apply the non-iron-based heterogeneous Fenton-like catalyst prepared by the above method to treatment of dye wastewater, specifically, adding the non-iron-based heterogeneous Fenton-like catalyst to the dye wastewater, stirring and adsorbing under light-proof conditions, and then adding H2O2 to degrade the dye by Fenton-like method.

[0008] Compared with the prior art, the present application has the following advantages and effects:

[0009] The catalyst preparation process of the present application is simple, environmentally friendly and low in consumption; the prepared non-iron-based heterogeneous Fenton-like catalyst has remarkable removal effect and reusability; can effectively remove methylene blue in wastewater, has higher cost performance than general catalysts, and has good application value in solving the actual pollution problems related to dyes in industrial wastewater. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 SEM image of the non-iron-based heterogeneous Fenton-like catalyst;

[0011] Figure 2 XPS image of the non-iron-based heterogeneous Fenton-like catalyst for methylene blue degradation treatment of the present application, wherein a is the full spectrum, b is Cu 2p, and c is Co 2p; Fresh represents before use, and Used represents after use;

[0012] Figure 3 Respectively, the removal effect of Comparative Example 1, Comparative Example 2 and Examples 1-5 on methylene blue;

[0013] Figure 4 Cycle effect diagram of the non-iron-based heterogeneous Fenton-like catalyst for methylene blue degradation treatment. DETAILED DESCRIPTION

[0014] In order to clearly illustrate the content of the present application, the present application will be further specifically and concretely described in combination with examples, but the scope of protection of the present application is not limited to the content described, and the chemical reagents used in the examples are all of analytical purity.

[0015] The formula for calculating the degradation rate of the catalyst on methylene blue in the examples is as follows:

[0016] Wherein, and respectively represent the initial concentration and the concentration at time t of methylene blue in the solution; Example 1

[0017] 1. Weigh 3 mmol of copper nitrate trihydrate and 2 mmol of trimesic acid into 24 mL of ethanol-water mixture (volume ratio 1:1), stir and mix, then transfer to a stainless steel reaction kettle with a polytetrafluoroethylene liner, and carry out hydrothermal reaction at 110°C. After the hydrothermal kettle cools to room temperature, centrifuge, wash the solid with anhydrous ethanol three times, and vacuum dry at 80°C.

[0018] 2. Take 0.06589 g of the dry solid powder from step 1 and add it to a 40 mL methanol solution containing 0.5821 g of cobalt nitrate, ultrasonic for 30 minutes, then add a 40 mL methanol solution containing 0.6568 g of 2-methylimidazole, magnetically stir at room temperature for 12 hours, stand for 12 hours, centrifuge, wash the solid with methanol three times, and vacuum dry at 60°C to obtain a non-iron-based heterogeneous Fenton-like catalyst.

[0019] 3. Prepare a 50 mL methylene blue solution with a concentration of 30 mg / L and place it in a conical flask, add 30 mg of non-iron-based heterogeneous Fenton-like catalyst to the methylene blue solution, magnetically stir in the dark for 30 minutes, then add 100 µL of H2O2 for Fenton-like degradation, filter with a filter head with a diameter of 0.22 µm, take the filtrate, measure the absorbance of the filtrate at λ max 663 nm with ultraviolet light, calculate the degradation rate of the catalyst on methylene blue, and the removal rate of methylene blue is 90.98% at 40 min. Example 2

[0020] 1. Weigh 3 mmol of copper nitrate trihydrate and 2 mmol of trimesic acid into 24 mL of ethanol-water mixture (volume ratio 1:1), stir and mix, then transfer to a stainless steel reaction kettle with a polytetrafluoroethylene liner, and carry out hydrothermal reaction at 110°C. After the hydrothermal kettle cools to room temperature, centrifuge, wash the solid with anhydrous ethanol three times, and vacuum dry at 80°C.

[0021] 2. Take 0.09225 g of the dry solid powder from step 1 and add it to a 40 mL methanol solution containing 0.5821 g of cobalt nitrate, ultrasonic for 30 minutes, then add a 40 mL methanol solution containing 0.6568 g of 2-methylimidazole, magnetically stir at room temperature for 12 hours, stand for 12 hours, centrifuge, wash the solid with methanol three times, and vacuum dry at 60°C to obtain a non-iron-based heterogeneous Fenton-like catalyst.

[0022] The SEM image of the catalyst of this example is shown in Figure 1 From the image, it can be seen that the surface of the large Cu-MOF crystals is uniformly coated with small metal-organic framework nanoparticles Co-MOF, confirming the successful formation of the non-iron-based heterogeneous Fenton-like catalyst.

[0023] The X-ray photoelectron spectroscopy (XPS) detection results of the non-iron-based heterogeneous Fenton-like catalyst prepared in this embodiment before and after use are shown in Figure 2 It can be seen from Figure 2 a that the peaks at 284.8 eV, 398.84 eV, 531.31 eV, 781.27 eV and 933.12 eV in the catalyst are attributed to C1s, N 1s, O 1s, Co 2p and Cu 2p, indicating that the composite material contains C, N, O, Co and Cu elements. Figure 2 In the Cu 2p spectrum of b, the peaks of Cu 2+ are located at 934.67 eV and 954.24 eV, and the peak of Cu + is located at 943.43 eV, which is attributed to a shake-up satellite peak. The peak of Cu + is located at 932.33 eV and 952.24 eV, and there is a shake-up satellite peak at about 938 eV. After use, the percentage content of Cu 2+ decreases from 79.26% to 19.31%, while the percentage content of Cu + increases from 20.74% to 80.69%, indicating that Cu 2+ on the surface is partially converted into Cu 2+ during the reaction. Figure 2 In the Co 2p spectrum of c, two main peaks are observed at 780.82 eV and 796.53 eV, which are characteristic peaks of Co-MOF, and two shake-up satellite peaks of Co 3+ are observed at 785.73 eV and 801.99 eV. The peak positions do not change significantly before and after use of the catalyst. The percentage content of Co 2+ increases from 68.78% to 74.77%, while the percentage content of Co 2+ decreases from 31.22% to 25.23%, indicating that Co 3+ is partially converted into Co 2+ during the reaction. The changes in the valence states of Cu + / Cu 3+ and Co 2+ / Co max also confirm that the redox between Cu 2+ / Cu + and Co 3+ / Co 2+ participates in the activation of H2O2;

[0024] 3. Prepare 50 mL of methylene blue solution with a concentration of 30 mg / L and place it in a conical flask. Add 30 mg of non-iron-based heterogeneous Fenton-like catalyst to the methylene blue solution. After magnetic stirring for 30 minutes in the dark, add 100 µL of H2O2 for Fenton-like degradation. Filter with a filter head with a diameter of 0.22 µm, take the filtrate, and measure the filtrate at λ max=663 nm, and calculated the degradation rate of methylene blue by the catalyst. The removal rate of methylene blue reached 92.41% in 40 min. Example 3

[0025] 1. Weigh 3 mmol of copper nitrate trihydrate and 2 mmol of trimesic acid and add them to 24 mL of ethanol-water mixture (volume ratio 1:1) in sequence. Stir and mix well, then transfer to a stainless steel reactor lined with polytetrafluoroethylene. Carry out hydrothermal reaction at 110°C. After cooling the reactor to room temperature, centrifuge the reaction mixture, wash the solid with anhydrous ethanol three times, and dry it in vacuum at 80°C.

[0026] 2. Take 0.1318 g of the dried solid powder from step 1 and add it to 40 mL of a methanol solution containing 0.5821 g of cobalt nitrate. Ultrasonicate for 30 minutes, then add 40 mL of a methanol solution containing 0.6568 g of 2-methylimidazole. Stir magnetically at room temperature for 12 hours, let stand for 12 hours, centrifuge, wash the solid three times with methanol, and vacuum dry at 60°C to obtain a non-iron-based heterogeneous Fenton-like catalyst.

[0027] 3. Prepare 50 mL of 30 mg / L methylene blue solution and place it in a conical flask. Add 30 mg of non-ferrous heterogeneous Fenton-like catalyst to the methylene blue solution. After magnetic stirring for 30 minutes under dark conditions, add 100 µL of H2O2 for Fenton-like degradation. Filter with a 0.22 µm diameter filter head and take the filtrate. The filtrate is measured by UV at λ max =663 nm, and calculated the degradation rate of methylene blue by the catalyst. The removal rate of methylene blue reached 89.74% in 40 min. Example 4

[0028] 1. Weigh 3 mmol of copper nitrate trihydrate and 2 mmol of trimesic acid and add them to 24 mL of ethanol-water mixture (volume ratio 1:1) in sequence. Stir and mix well, then transfer to a stainless steel reactor lined with polytetrafluoroethylene. Carry out hydrothermal reaction at 110°C. After cooling the reactor to room temperature, centrifuge the reaction mixture, wash the solid with anhydrous ethanol three times, and dry it in vacuum at 80°C.

[0029] 2. Take 0.1977 g of the dried solid powder from step 1 and add it to 40 mL of a methanol solution containing 0.5821 g of cobalt nitrate. Ultrasonicate for 30 minutes, then add 40 mL of a methanol solution containing 0.6568 g of 2-methylimidazole. Stir magnetically at room temperature for 12 hours, let stand for 12 hours, centrifuge, wash the solid three times with methanol, and vacuum dry at 60°C to obtain a non-iron-based heterogeneous Fenton-like catalyst.

[0030] 3. Prepare 50 mL methylene blue solution with a concentration of 30 mg / L and place it in a conical flask. Add 30 mg of non-iron-based heterogeneous Fenton-like catalyst to the methylene blue solution. After stirring magnetically for 30 minutes in the dark, add 100 μL of H2O2 for Fenton-like degradation. Filter with a filter head of 0.22 μm in diameter, take the filtrate, and measure the absorbance of the filtrate at λ663 nm using ultraviolet spectroscopy. Calculate the degradation rate of the catalyst on methylene blue, and the removal rate of methylene blue is 87.15% at 40 min. max =663 nm, and the removal rate of methylene blue is 87.15% at 40 min. Example 5

[0031] 1. Weigh 3 mmol of copper nitrate trihydrate and 2 mmol of trimesic acid, and add them to 24 mL of an ethanol-water mixture (volume ratio 1:1) in sequence. After stirring and mixing, transfer to a stainless steel reaction kettle with a polytetrafluoroethylene liner, and perform hydrothermal reaction at 110°C. After the hydrothermal kettle cools to room temperature, centrifuge, wash the solid with anhydrous ethanol 3 times, and vacuum dry at 80°C.

[0032] 2. Take 0.2636 g of the dried solid powder from step 1 and add it to a 40 mL methanol solution containing 0.5821 g of cobalt nitrate. Sonicate for 30 minutes, then add a 40 mL methanol solution containing 0.6568 g of 2-methylimidazole. Stir magnetically at room temperature for 12 hours, stand for 12 hours, centrifuge, wash the solid with methanol 3 times, and vacuum dry at 60°C to obtain a non-iron-based heterogeneous Fenton-like catalyst.

[0033] 3. Prepare 50 mL methylene blue solution with a concentration of 30 mg / L and place it in a conical flask. Add 30 mg of non-iron-based heterogeneous Fenton-like catalyst to the methylene blue solution. After stirring magnetically for 30 minutes in the dark, add 100 μL of H2O2 for Fenton-like degradation. Filter with a filter head of 0.22 μm in diameter, take the filtrate, and measure the absorbance of the filtrate at λ663 nm using ultraviolet spectroscopy. Calculate the degradation rate of the catalyst on methylene blue, and the removal rate of methylene blue is 87.15% at 40 min. max =663 nm, and the removal rate of methylene blue is 87.15% at 40 min.

[0034] Comparative Example 1

[0035] Weigh 3 mmol of copper nitrate trihydrate and 2 mmol of trimesic acid, and add them to 24 mL of an ethanol-water mixture (volume ratio 1:1) in sequence. After stirring and mixing, transfer to a stainless steel reaction kettle with a polytetrafluoroethylene liner, and perform hydrothermal reaction at 110°C. After the hydrothermal kettle cools to room temperature, centrifuge, wash the solid with anhydrous ethanol 3 times, and vacuum dry at 80°C to obtain a Cu-MOF catalyst.

[0036] Comparative Example 2

[0037] Take 2 mmol of cobalt nitrate dissolved in 40 mL of methanol solution, add 8 mmol of 2-methyl imidazole in methanol solution 40 mL, magnetic stirring at room temperature for 12 hours, stand for 12 hours, centrifugation, the solid is washed with methanol 3 times, vacuum drying at 60℃ to obtain Co-MOF catalyst.

[0038] The removal effect of methylene blue by the catalysts in examples 1-5 and comparative examples 1-2 is shown in Table 1, and the results show that the non-iron-based heterogeneous Fenton-like catalysts of the present application can effectively remove methylene blue in wastewater, and the effect is better than that of the catalysts of comparative examples. Figure 3

[0039] Example 6: Recycling experiment of non-iron-based heterogeneous Fenton-like catalyst

[0040] The catalyst used in example 2 was used to complete the degradation experiment, high-speed centrifugation was used to separate the MB degradation products and the catalyst, the precipitate was washed with anhydrous methanol several times, and after drying at 60℃ for 12h, grinding was used to remove methylene blue in wastewater, and the use method was the same as example 2, and the results are shown in Table 2. Figure 4 After 5 times of recycling, the removal rate of methylene blue decreased slightly, but the removal rate after the fifth recycling remained at 80.61%, indicating that the catalyst had potential reusability.​

Claims

1. Application of a non-ferrous heterogeneous Fenton-like catalyst in treating dye wastewater, characterized in that: The non-iron-based heterogeneous Fenton-type catalyst is prepared by sequentially adding copper nitrate trihydrate and trimesic acid to an ethanol-water mixture, mixing them evenly, performing a hydrothermal reaction at 80-140° C., performing solid-liquid separation, and washing and drying the solid to obtain a solid product. The solid product is dispersed in a methanol solution containing cobalt nitrate, and then a methanol solution containing 2-methylimidazole is added and stirred for 10-15 hours, and then allowed to stand for 10-15 hours, solid-liquid separation is performed, and the solid is washed and dried to obtain the product; The dye is methylene blue, and H2O2 is added to perform Fenton-like degradation of the dye.

2. The use according to claim 1, characterized in that: The molar ratio of copper nitrate trihydrate to trimesic acid is 1.5-2:1, and the ethanol-water mixed liquid is prepared by mixing ethanol and water in a volume ratio of 1-2:

1.

3. The use according to claim 1, characterized in that: The mass ratio of the solid product to cobalt nitrate is 0.1-0.5:1, and the molar ratio of cobalt nitrate to 2-methylimidazole is 1:4-8.

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