Iron and manganese loaded nano aluminum oxide catalyst as well as preparation method and application thereof

Abstract

The invention relates to an iron-manganese supported nano aluminum trioxide catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: 1) preparing a ferro-manganese metal alkoxide solution; (2) adding nano aluminum oxide into the iron-manganese metal alkoxide solution obtained in the step (1), heating in a water bath, stirring, and then separating to obtain iron-manganese loaded aluminum oxide; and (3) drying the iron and manganese loaded aluminum oxide in the step (2), and then calcining to obtain the iron and manganese loaded nano aluminum oxide catalyst. The catalyst is simple in preparation process and low in production cost. Moreover, the treatment efficiency of the catalytic ozonation method depends on the activity of the catalyst, and the supported catalyst can enhance the adsorption of O3 and organic matters in water and promote the chain free radical reaction. Fe and Mn in the transition metal have various oxidation forms, so that electron transfer is facilitated, O3 is promoted to generate. OH, and good catalytic activity is shown in sewage treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic addition, and particularly relates to a catalyst of iron and manganese supported on nano-aluminum oxide, a preparation method thereof, and an application thereof. Background Art

[0002] With the increasingly severe problem of water resource shortage, the advanced treatment and reuse of urban sewage have become an important way to alleviate the water resource tension. The reuse of urban sewage refers to the process of taking the secondary effluent of a urban sewage treatment plant, adopting an advanced treatment process according to different reuse targets, making it meet specific standards and then being utilized. Although the secondary effluent of the sewage treatment plant has been treated, there are still some refractory organic matters and trace pharmaceutical pollutants in the water body, which are difficult to be further degraded by traditional biological treatment methods. Therefore, it is necessary to implement an advanced treatment process for the secondary effluent of urban sewage treatment plants to improve the water quality standard and meet the reclaimed water reuse standard.

[0003] The core mechanism of the ozonation technology depends on the direct oxidation reaction of ozone molecules with organic matters. However, the limitation of this technology is that O3 has strong selectivity for organic matters, resulting in a slow oxidation rate and limited mineralization efficiency, and it is difficult to achieve the complete decomposition of pollutants. Therefore, developing a catalyst with good catalytic effect, long service life and high reuse rate is the key research content at present. The present invention improves the shortcomings of the traditional single ozone treatment technology, uses a material of iron and manganese supported on nano-aluminum oxide to catalyze ozone, enhances the ozone utilization efficiency, and improves the advanced treatment effect of the secondary effluent. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of an iron and manganese supported nano-aluminum oxide catalyst to solve the above technical problems existing in the prior art.

[0005] The second purpose of the present invention also lies in providing an iron and manganese supported nano-aluminum oxide catalyst.

[0006] The third purpose of the present invention also lies in providing an application of an iron and manganese supported nano-aluminum oxide catalyst.

[0007] To achieve the above purpose, a preparation method of an iron and manganese supported nano-aluminum oxide catalyst of the present invention adopts the following technical scheme: A preparation method of an iron and manganese supported nano-aluminum oxide catalyst, comprising the following steps:

[0008] 1) Prepare an iron and manganese metal alkoxide solution;

[0009] 2) Add nano-aluminum oxide to the iron and manganese metal alkoxide solution obtained in step 1), heat in a water bath and stir, and then separate to obtain iron and manganese supported aluminum oxide;

[0010] 3) Dry the iron and manganese supported aluminum oxide in step 2), and then calcine it to obtain an iron and manganese supported nano-aluminum oxide catalyst.

[0011] In step 1), take iron nitrate and manganese nitrate with a molar ratio of 1:7 and dissolve them in absolute ethanol to prepare an iron and manganese metal alkoxide solution.

[0012] In step 2), γ-Al2O3 is selected as the nano-aluminum oxide.

[0013] In step 2), the temperature of the water bath heating is 65 °C.

[0014] In step 2), the stirring time is 2 h.

[0015] In step 3), the drying conditions are 105 °C and the drying time is 10 h.

[0016] In step 3), the dried iron and manganese supported aluminum oxide is placed in a tube furnace for calcination.

[0017] The calcination conditions are 650 °C and the calcination time is 8 h.

[0018] An iron and manganese supported nano-aluminum oxide catalyst is prepared by using the above preparation method of the iron and manganese supported nano-aluminum oxide catalyst.

[0019] An application of an iron and manganese supported nano-aluminum oxide catalyst in the catalytic ozonation treatment of sewage.

[0020] The beneficial effects of the present invention: The catalyst preparation process of the present invention is simple and the production cost is low. Moreover, the treatment efficiency of the catalytic ozonation method depends on the activity of the catalyst. Among them, the supported catalyst of the present invention can enhance the adsorption of O3 and organic matter in water and promote the progress of the chain radical reaction. Fe and Mn in transition metals have multiple oxidation states, which is beneficial to electron transfer, thereby promoting the generation of ·OH from O3 and showing good catalytic activity in sewage treatment. Description of the Drawings

[0021] Figure 1 is the SEM characterization diagram of nano-aluminum oxide and the iron and manganese supported nano-aluminum oxide catalyst of the present invention;

[0022] Figure 2 is the XRD characterization diagram of the iron and manganese supported nano-aluminum oxide catalyst of the present invention;

[0023] Figure 3 is the comparison diagram of the COD removal rate of the experimental example and the comparative example of the present invention in sewage;

[0024] Figure 4It is the ultraviolet absorption wavelength scanning chart before and after sewage treatment by using the catalyst prepared in the embodiment of the present invention in combination with ozone;

[0025] Figure 5 It is the change chart of UV before and after sewage treatment by using the catalyst prepared in Example 1 of the present invention in combination with ozone 254 . Specific implementation mode

[0026] Next, the technical solution of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0027] Experimental example

[0028] Take ferric nitrate and manganese nitrate with a molar ratio of 1:7 and dissolve them in 50 mL of absolute ethanol to prepare an iron-manganese metal alkoxide solution. Add 10 g of nano-γ-Al2O3 to this solution, then place it in water at 65 °C for water bath heating, and stir for 2 h. Subsequently, separate to obtain an iron-manganese supported alumina solid substance. Then dry the iron-manganese supported alumina solid substance at 105 °C for 10 h. Finally, place the obtained dried iron-manganese supported alumina in a tubular furnace and calcine it at 650 °C for 8 h in a nitrogen atmosphere. The obtained product is the iron-manganese supported nano-alumina catalyst.

[0029] Scanning electron microscopy observations were carried out on nano-aluminum dioxide and the obtained iron-manganese supported nano-alumina catalyst respectively. Its SEM characterization diagram is as Figure 1 shown. It can be seen that compared with the nano-aluminum dioxide carrier, the iron-manganese supported nano-alumina catalyst has a rich pore structure.

[0030] XRD analysis was carried out on the iron-manganese supported nano-alumina catalyst of the present invention. Its characterization diagram is as Figure 2 shown. It can be seen that Fe3O4, MnFe2O4 and Mn3O4 are the main crystal phases of the iron-manganese composite catalyst.

[0031] Inductively coupled plasma atomic emission spectrometry (ICP) was used to determine the actual loading amounts of iron and manganese on the iron-manganese supported nano-alumina catalyst of the present invention. The results are shown in the following table. It shows that the actual loading amount of iron is 29.96 mg / g, and the element content ratio is 3.00%. The actual loading amount of manganese is 28.29 mg / g, and the element content ratio is 2.83%. It shows that the iron-manganese loading ratio of the catalyst is about 1:1.

[0032]

[0033] In terms of sewage treatment:

[0034] The process operating conditions are as follows: Simulated secondary effluent of a sewage treatment plant with 50 mg / l COD self-prepared from humic acid is used, 5 mmol / l sodium dihydrogen phosphate buffer solution is added, and NaOH is added to adjust the pH to 7.5. Take 1 L of the above water sample, with an initial COD concentration of 50 mg / L, a catalyst dosage of 2.5 g / L, an inlet gas rate of 0.2 L / min, and an O3 concentration of 25 mg / L, and conduct the experiment.

[0035] The comparative example only uses ozone. The experimental results of the above experimental examples and comparative examples are as Figure 3 shown. It can be seen that the COD removal rate increased from 36.6% to 57.9% at 60 min after the catalyst was added.

[0036] Figure 4 It is the ultraviolet absorption wavelength scanning diagram of the wastewater before and after the reaction under the optimal conditions using an ultraviolet spectrophotometer. It can be seen that the ultraviolet absorption spectrum of the treated sewage shows a downward trend compared with that before treatment, indicating that the pollutants in the treated sewage have changed significantly.

[0037] Figure 5 It is the change diagram of UV254 before and after the wastewater reaction. It can be seen that UV254 decreased from 0.2619 to 0.0467, indicating that the humus in the sewage may be converted into non-humus, and the hardly biodegradable organic matter is effectively removed.

Claims

1. A preparation method of an iron and manganese loaded nano-aluminum oxide catalyst, characterized in that, It includes the following steps: 1) Prepare an iron-manganese metal alkoxide solution; 2) Add nano-aluminum oxide to the iron-manganese metal alkoxide solution obtained in step 1), heat it in a water bath and stir, and then separate to obtain iron-manganese supported aluminum oxide; 3) Dry the iron-manganese supported aluminum oxide in step 2), and then calcine it to obtain an iron-manganese supported nano-aluminum oxide catalyst.

2. The preparation method of the iron-manganese supported nano-aluminum oxide catalyst according to claim 1, characterized in that: In step 1), ferric nitrate and manganese nitrate with a molar ratio of 1:7 are dissolved in absolute ethanol to prepare an iron-manganese metal alkoxide solution.

3. The preparation method of the iron-manganese supported nano-aluminum oxide catalyst according to claim 1, characterized in that: In step 2), the nano-aluminum oxide is γ-Al2O3.

4. The preparation method of the iron and manganese loaded nano-aluminum oxide catalyst according to claim 1, characterized in that: In step 2), the temperature of the water bath heating is 65°C.

5. The preparation method of the iron and manganese loaded nano-aluminum oxide catalyst according to claim 1, characterized in that: In step 2), the stirring time is 2 h.

6. The preparation method of the iron and manganese loaded nano-aluminum oxide catalyst according to claim 1, characterized in that: In step 3), it is dried in a nitrogen environment, and the drying conditions are 105°C and the drying time is 10 h.

7. The preparation method of the iron and manganese loaded nano-aluminum oxide catalyst according to claim 1, characterized in that: In step 3), the dried iron-manganese supported aluminum oxide is placed in a tube furnace for calcination.

8. The preparation method of the iron-manganese loaded nano-aluminum oxide catalyst according to claim 7, characterized in that: The calcination conditions are 650°C and calcination for 8 h.

9. A nano-aluminum oxide catalyst loaded with iron and manganese, characterized in that: It is prepared by using the preparation method of the iron-manganese supported nano-aluminum oxide catalyst described in claim 1.

10. Application of an iron-manganese loaded nano-aluminum oxide catalyst, characterized in that: It is used for catalytic ozonation treatment of sewage.

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