Iron-manganese bimetallic ozone catalyst, preparation method and application

Abstract

The invention relates to the technical field of ozone catalysts, in particular to an iron-manganese bimetallic ozone catalyst as well as a preparation method and application thereof. The iron-manganese bimetallic ozone catalyst comprises an activated carbon carrier and an iron-manganese bimetallic oxide loaded on the activated carbon carrier, in the preparation process of the iron-manganese double-metal ozone oxidizing agent, anhydrous nitrate of ferric iron and divalent manganese is adopted and dissolved in absolute ethyl alcohol, then activated carbon is added for excessive dipping, drying and under-pressure calcination, and the iron-manganese double-metal ozone oxidizing agent can be obtained. When the ferro-manganese bimetallic ozone oxidizing agent is combined with ozone to remove refractory COD (Chemical Oxygen Demand) in advanced sewage treatment, the ferro-manganese bimetallic ozone oxidizing agent shows relatively good catalytic activity, the removal rate of the refractory COD in the advanced sewage treatment can reach 57.9 percent within 60 minutes, and the ferro-manganese bimetallic ozone oxidizing agent has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of ozone catalysts, and in particular to an iron-manganese bimetallic ozone catalyst, a preparation method and application thereof. Background Art

[0002] The existing deep treatment processes mainly include coagulation and sedimentation, activated carbon adsorption, membrane treatment process, biological treatment, advanced oxidation technology and the combination or joint use of the above processes; ozone oxidation uses the strong oxidizing property of ozone to achieve the oxidation of organic matter. Ozone is easy to use and does not produce secondary pollution. It can effectively disinfect and remove color in wastewater treatment. It is a green and environmentally friendly sewage deep treatment technology.

[0003] COD in sewage deep treatment is difficult to biodegrade and difficult to remove by ordinary methods. Zheng Xiaoying et al. found in an experiment on ozone oxidation of organic matter in the secondary biochemical tail water of municipal sewage that when the ozone dosage reached 10 mg / L, the COD removal rate was 26.60%. 254 The removal rate of ozone was 59.50%, and the removal rate of TOC was only 9.60%. When the ozone dosage continued to increase, TOC, COD, UV 254 There is no change; it is not difficult to see that when ozone is used alone to treat municipal sewage, the ozone utilization rate is low and the cost is high. Improving the efficiency of ozone utilization has become a hot topic in the research of this technology.

[0004] Therefore, developing a catalyst with good catalytic effect, long life and high reuse rate for use in combination with ozone is the focus of current research. The present invention improves on the shortcomings of traditional ozone treatment technology alone, uses iron-manganese loaded activated carbon materials to catalyze ozone, enhances ozone utilization efficiency, and improves the deep treatment effect of secondary effluent. Summary of the invention

[0005] The purpose of the present invention is to provide an iron-manganese bimetallic ozone catalyst, a preparation method and an application thereof, so as to solve the problem of low COD removal rate when ozone is used alone to remove refractory COD in sewage deep treatment.

[0006] To achieve the above object, the present invention adopts the following technical scheme: an iron-manganese bimetallic ozone catalyst, the catalyst only comprising a carrier and a metal oxide supported on the carrier;

[0007] The carrier is only activated carbon;

[0008] The metal oxide is only iron-manganese bimetallic oxide.

[0009] Furthermore, the iron-manganese bimetallic oxide has a mixed crystal phase, including spinel Fe3O4 and spinel ferrite MnFe2O4 with ferromagnetism.

[0010] The preparation method of the iron-manganese bimetallic ozone catalyst comprises the following steps:

[0011] S1. Take nitrates of trivalent iron and divalent manganese, and dissolve them in anhydrous ethanol to obtain a metal alkoxide solution;

[0012] S2, adding activated carbon to the metal alkoxide solution obtained in S1, stirring in a water bath and separating to obtain loaded activated carbon;

[0013] S3, drying and calcining the loaded activated carbon obtained in S2 to obtain the iron-manganese bimetallic ozone catalyst of the present invention.

[0014] Furthermore, in the S1, the nitrates of trivalent iron and divalent manganese are both anhydrous nitrates, and both ferric nitrate and manganese nitrate are solid and do not contain bound water; the molar concentration of ferric nitrate in the metal alkoxide solution is 0.7 mol / L, and the molar concentration of manganese nitrate in the metal alkoxide solution is 0.1 mol / L.

[0015] Furthermore, in the S2, the particle size of the activated carbon is 4 to 6 mm; and the volume ratio of the mass of the activated carbon to the anhydrous ethanol is 1:10.

[0016] Furthermore, in the S2, the stirring temperature in the water bath is 60° C., the stirring time is 2 h, and the stirring intensity is 120 rpm.

[0017] Furthermore, in the S3, the drying temperature is 105°C, and the drying time is 12 hours; the calcination temperature is 600°C, and the calcination time is 8 hours.

[0018] Application of iron-manganese bimetallic ozone catalyst, the iron-manganese bimetallic ozone catalyst is applied to the removal of refractory COD in deep sewage treatment.

[0019] Furthermore, the mass ratio of the dosage of the iron-manganese bimetallic ozone catalyst to the refractory COD in the sewage is 40:1, the ozone inlet concentration is 25 mg / L, and the ozone inlet rate is 0.2 L / min.

[0020] Furthermore, the removal rate of the difficult-to-degrade COD in the sewage deep treatment can reach 57.9% in 60 minutes.

[0021] Beneficial effects of the present invention:

[0022] 1. The preparation method of the present invention has a simple process flow, low production and preparation cost, is conducive to the control of use cost, and is more convenient for use in actual production;

[0023] 2. The iron-manganese bimetallic ozone catalyst of the present invention exhibits good catalytic activity when used in combination with ozone to remove refractory COD in deep sewage treatment. The removal rate of refractory COD in deep sewage treatment can reach 57.9% in 60 minutes, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a process flow chart of the catalyst preparation of the present invention;

[0025] Figure 2 This is a SEM characterization image of the carrier activated carbon used in Example 1 of the present invention;

[0026] Figure 3 is a SEM characterization image of the catalyst prepared in Example 1 of the present invention;

[0027] Figure 4 is the XRD characterization diagram of the catalyst prepared in Example 1 of the present invention;

[0028] Figure 5 is the XPS fine spectrum of Fe 2p of the catalyst prepared in Example 1 of the present invention;

[0029] Figure 6 is the XPS fine spectrum of Mn 2p of the catalyst prepared in Example 1 of the present invention;

[0030] Figure 7 It is a comparison chart of the removal effect of COD by ozone alone and by ozone catalyzed by the catalyst prepared in Example 1 of the present invention;

[0031] Figure 8 This is a scanning diagram of ultraviolet absorption wavelength before and after sewage treatment using the catalyst prepared in Example 1 of the present invention in combination with ozone;

[0032] Fig. 9 The catalyst prepared in Example 1 of the present invention is combined with ozone to treat the UV radiation before and after sewage treatment. 254 ;

[0033] Fig.10 It is a comparison chart of the removal effects of the catalyst prepared in Example 1 of the present invention and the catalyst prepared in Comparative Example 1 on the same batch of sewage's difficult-to-degrade COD. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0035] Example 1

[0036] Accurately take 8.470g of anhydrous ferric nitrate and 0.895g of anhydrous manganese nitrate and dissolve them in 50mL of anhydrous ethanol to obtain a metal alkoxide solution; add 5g of activated carbon carrier to the obtained metal alkoxide solution for impregnation, and the particle size of the activated carbon carrier is 4-6mm; then stir for 2h in a 60℃ water bath with a stirring intensity of 120rpm. After stirring, filter and separate to obtain loaded activated carbon.

[0037] The obtained loaded activated carbon was dried at 105° C. for 12 h, and then placed in a tubular furnace for calcination at a temperature of 600° C. for 8 h to obtain an iron-manganese bimetallic ozone catalyst.

[0038] The activated carbon carrier used in this example and the prepared catalyst were characterized by SEM. It can be seen that compared with the pure activated carbon carrier, the catalyst of the present invention has a rich pore structure.

[0039] The BET specific surface area of ​​the activated carbon and the obtained catalyst was measured, and the results are shown in the following table:

[0040] Table 1 BET results of activated carbon carrier and catalyst

[0041]

[0042] It can be seen that the specific surface area and micropore specific surface area of ​​the activated carbon carrier increased after treatment, indicating that more surface active sites were exposed, which is beneficial to the catalytic ozone oxidation of pollutants.

[0043] The prepared catalyst was characterized by XRD. Figure 4 As shown, it can be seen that spinel Fe3O4 and spinel ferrite MnFe2O4 with ferromagnetism are the main crystal phases of the catalyst of the present invention.

[0044] The XPS fine spectrum of Fe 2p of the prepared catalyst was analyzed, and the results were as follows: Figure 5 As shown, the peaks at 711.0 eV and 724.0 eV are attributed to Fe 2+ The 2p3 / 2 and 2p1 / 2 spin orbits of 3+ The 2p3 / 2 and 2p1 / 2 spin orbits of the 2p3 / 2 and 2p1 / 2 spin orbits; the peaks at 717.5 eV and 731.9 eV are attributed to the satellite peaks of Fe; indicating the presence of Fe 2+ and Fe 3+ , the content ratio is 47.19%:52.81%.

[0045] The XPS fine spectrum of Mn 2p of the prepared catalyst was analyzed, and the results were as follows: Figure 6As shown, the peaks at 641.5 eV and 653.3 eV are attributed to Mn 2+ The 2p3 / 2 and 2p1 / 2 spin orbits of 4+ The 2p3 / 2 and 2p1 / 2 spin orbits of the Mn2+ and Mn2+ atoms are shown in Table 1. The peak at 646.4 eV is attributed to the satellite peak of Mn2+. 2+ and Mn 4+ , the content ratio is 55.15%:44.85%.

[0046] The prepared catalyst was used to remove refractory COD in deep sewage treatment. 50 mg / L refractory COD simulated wastewater was prepared, 5 mmol / l sodium dihydrogen phosphate buffer was added, and NaOH was added to adjust the pH to 7.5. The reaction was carried out for 60 minutes under the conditions of catalyst dosage of 2 g / L, ozone inlet concentration of 25 mg / L, and air intake rate of 0.2 L / min.

[0047] The results of adding the catalyst of the present invention and treating with ozone alone are as follows: Figure 7 As shown, it can be seen that the COD removal rate increased from 36.6% to 57.9% 60 minutes after the addition of the catalyst.

[0048] The ultraviolet absorption wavelength scanning of the sewage treated with the catalyst + ozone of the present invention is as follows: Figure 8 As shown, 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.

[0049] The ultraviolet absorbance of the wastewater treated with the catalyst + ozone of the present invention at 254 nm was measured. Fig. 9 As shown, we can see that UV 254 It dropped from 0.2619 to 0.0467, indicating that the humus in the sewage could be converted into non-humus and the difficult-to-biodegrade organic matter was effectively removed.

[0050] Comparative Example 1

[0051] In this comparative example, the solvent anhydrous ethanol in Example 1 was replaced by water, and the other steps were the same as in Example 1, and finally an iron-manganese bimetallic ozone catalyst was obtained.

[0052] The iron-manganese bimetallic ozone catalyst obtained in this comparative example was used to treat the sewage prepared in Example 1. The treatment results were compared with those in Example 1. Fig.10 shown.

[0053] It can be seen that the treatment effect of the iron-manganese bimetallic ozone catalyst obtained by using water as the solvent is obviously inferior to the effect of the present invention using anhydrous ethanol as the solvent.

[0054] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. An iron-manganese bimetallic ozone catalyst, characterized in that: The catalyst only includes a carrier and a metal oxide supported on the carrier; The carrier is only activated carbon; The metal oxide is only iron-manganese bimetallic oxide.

2. The iron-manganese bimetallic ozone catalyst according to claim 1, characterized in that: The iron-manganese bimetallic oxide has a mixed crystal phase, including spinel Fe3O4 and spinel ferrite MnFe2O4 with ferromagnetism.

3. The method for preparing the iron-manganese bimetallic ozone catalyst according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Take nitrates of trivalent iron and divalent manganese, and dissolve them in anhydrous ethanol to obtain a metal alkoxide solution; S2, adding activated carbon to the metal alkoxide solution obtained in S1, stirring in a water bath and separating to obtain loaded activated carbon; S3, drying and calcining the loaded activated carbon obtained in S2 to obtain the iron-manganese bimetallic ozone catalyst of the present invention.

4. The method for preparing the iron-manganese bimetallic ozone catalyst according to claim 3, characterized in that: In the S1, the nitrates of trivalent iron and divalent manganese are both anhydrous nitrates, and both ferric nitrate and manganese nitrate are solid and do not contain bound water; the molar concentration of ferric nitrate in the metal alkoxide solution is 0.7 mol / L, and the molar concentration of manganese nitrate in the metal alkoxide solution is 0.1 mol / L.

5. The method for preparing the iron-manganese bimetallic ozone catalyst according to claim 3, characterized in that: In the S2, the particle size of the activated carbon is 4 to 6 mm; the volume ratio of the mass of the activated carbon to the anhydrous ethanol is 1:

10.

6. The method for preparing the iron-manganese bimetallic ozone catalyst according to claim 3, characterized in that: In the S2, the stirring temperature in the water bath is 60° C., the stirring time is 2 h, and the stirring intensity is 120 rpm.

7. The method for preparing the iron-manganese bimetallic ozone catalyst according to claim 3, characterized in that: In the S3, the drying temperature is 105°C and the drying time is 12h; the calcination temperature is 600°C and the calcination time is 8h.

8. The use of the iron-manganese bimetallic ozone catalyst according to any one of claims 1 to 7, characterized in that: The iron-manganese bimetallic ozone catalyst is used for removing refractory COD in deep sewage treatment.

9. The use of the iron-manganese bimetallic ozone catalyst according to claim 8, characterized in that: The mass ratio of the dosage of the iron-manganese bimetallic ozone catalyst to the refractory COD in the sewage is 40:1, the ozone inlet concentration is 25 mg / L, and the ozone inlet rate is 0.2 L / min.

10. The use of the iron-manganese bimetallic ozone catalyst according to claim 9, characterized in that: In the sewage deep treatment, the removal rate of the difficult-to-degrade COD in 60 minutes can reach 57.9%.

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