Preparation method and application of ozone catalyst

Abstract

The invention relates to the technical field of ozone catalysts, in particular to a preparation method and application of an ozone catalyst. According to the ozone catalyst, gamma-Al2O3 is adopted as a carrier, iron and manganese bimetals are loaded on the carrier, when the ozone catalyst is applied to advanced sewage treatment, the removal rate of refractory COD can reach 58.64% within 60 min, meanwhile, the dissolution amount of iron ions and manganese ions of the ozone catalyst is small, the dissolution amount of the iron ions is smaller than 0.08 mg / L, the dissolution amount of the manganese ions is smaller than 0.08 mg / L, and the dissolution amount of the iron ions is smaller than 0.08 mg / L. The dissolution amount of manganese ions is less than 0.03 mg / L, so that the quality of effluent water can be ensured. The preparation method disclosed by the invention is simple in process flow, good in ozone catalytic oxidation effect, low in production and preparation cost, beneficial to control of use cost, capable of ensuring the quality of effluent, more convenient to use in actual production and wide in application prospect.

Description

Technical Field

[0001] This invention relates to the field of ozone catalyst technology, specifically to a method for preparing an ozone catalyst and its application. Background Technology

[0002] Existing advanced treatment processes mainly include coagulation sedimentation, activated carbon adsorption, membrane treatment, biological treatment, advanced oxidation technology, and combinations or combined use of the above processes. Ozone oxidation utilizes the strong oxidizing properties of ozone to oxidize organic matter. Ozone is easy to use, does not produce secondary pollution, and can effectively disinfect and decolorize wastewater, making it a green and environmentally friendly advanced wastewater treatment technology.

[0003] The COD in advanced wastewater treatment is biodegradable COD, which is difficult to remove using conventional methods. Zheng Xiaoying et al., in their experiment on ozone oxidation of organic matter in secondary biological treatment effluent of municipal wastewater, found 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%, while the removal rate of TOC was only 9.60%. When the ozone dosage continued to increase, the levels of TOC, COD, and UV in the effluent increased. 254 There were no changes; it is not difficult to see that ozone utilization is low and cost is high when ozone is used alone to treat municipal sewage, and improving ozone utilization efficiency has become a hot topic in this technology research.

[0004] Therefore, developing catalysts with good catalytic effect, long life and high reusability for use in combination with ozone is a current research focus. Existing ozone catalysts have been extensively studied, but during use, they often result in high concentrations of metal ions leached from the catalyst in the effluent, thus affecting the quality of the effluent. Therefore, an ozone catalyst that can reduce the leaching of metal ions from the catalyst and thus further ensure the quality of the effluent is a technical problem that needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an ozone catalyst and its application, so as to solve the problem that the concentration of metal ions dissolved in the effluent from existing ozone catalysts is high during use, which affects the quality of the effluent.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing an ozone catalyst, comprising the following steps:

[0007] S1. Take nitrates of ferric iron and divalent manganese and dissolve them completely in water to obtain a mixed solution;

[0008] S2. Add anhydrous citric acid and γ-Al2O3 to the obtained mixed solution, heat and stir thoroughly to obtain the sol precursor;

[0009] S3. The obtained sol precursor is dried and calcined to obtain the ozone catalyst of the present invention.

[0010] Furthermore, the ferric nitrate is ferric nitrate nonahydrate, and the manganese nitrate is manganese nitrate tetrahydrate.

[0011] Furthermore, in S1-S2, the molar ratio of ferric nitrate, manganese nitrate, anhydrous citric acid, and γ-Al2O3 is 1:3~8:1~5:5~10.

[0012] Furthermore, in S2, the water bath stirring temperature is 60-80℃, the stirring time is 1-3 hours, and the stirring intensity is 100-200 rpm.

[0013] Furthermore, in S3, the drying temperature is 105–120°C, and the drying time is 2–6 hours.

[0014] Furthermore, in S3, calcination is carried out in a tube furnace, and the atmosphere during calcination is air with an air flow rate of 0.5–1.0 L / min.

[0015] Furthermore, the calcination temperature is 500–600°C, and the calcination time is 4–8 hours.

[0016] The application of ozone catalysts, specifically the removal of recalcitrant COD in advanced wastewater treatment.

[0017] Furthermore, the dosage of the ozone catalyst is in a mass ratio of 30 to 40:1 to the recalcitrant COD in the wastewater, the initial pH is 8, the hydraulic retention time is 1.5 h, the ozone inlet concentration is 35 mg / L, and the ozone inlet rate is 0.2 L / min.

[0018] Furthermore, in the aforementioned advanced wastewater treatment, the removal rate of recalcitrant COD can reach 58.64% within 60 minutes, the iron ion leaching amount is less than 0.08 mg / L, and the manganese ion leaching amount is less than 0.03 mg / L.

[0019] The beneficial effects of this invention are:

[0020] 1. The preparation method of this invention has a simple process flow, low production cost, and is conducive to cost control, making it more convenient for use in actual production;

[0021] 2. The ozone catalyst of this invention exhibits good catalytic activity when combined with ozone for the removal of recalcitrant COD in advanced wastewater treatment. The removal rate of recalcitrant COD in advanced wastewater treatment can reach 58.64% in 60 minutes, showing broad application prospects.

[0022] 3. The ozone catalyst of this invention has low iron and manganese ion dissolution during the deep treatment of wastewater, which helps to ensure the quality of the effluent. Attached Figure Description

[0023] Figure 1 This is a diagram illustrating the effect of the ozone catalyst of this invention on catalytic ozone oxidation;

[0024] Figure 2 This is a graph showing the change in the amount of Fe ions dissolved in the ozone catalyst of this invention over time.

[0025] Figure 3 This is a graph showing the change in the amount of Mn ions dissolved in the ozone catalyst of this invention over time. Detailed Implementation

[0026] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0027] Example 1

[0028] Accurately dissolve 4.04 g of Fe(NO3)3·9H2O and 12.55 g of Mn(NO3)2·4H2O in 100 mL of water and stir thoroughly to obtain a mixed solution. Add 4.4 g of anhydrous citric acid to the obtained mixed solution and stir to dissolve. Then add 8 g of γ-Al2O3 with a particle size of 3-5 mm. Heat in a water bath at 70 °C and stir for 1 h at a stirring intensity of 120 rpm to obtain a sol precursor.

[0029] The obtained sol precursor was dried at 115℃ for 2-6 hours, and then placed in a tube furnace for calcination at an air atmosphere of 0.8 L / min for 6 hours to obtain the ozone catalyst.

[0030] The catalyst was found to contain 4.57% iron and 5.80% manganese.

[0031] The prepared catalyst was used for the removal of recalcitrant COD in the advanced treatment of wastewater. A simulated wastewater with 60 mg / L of recalcitrant COD was prepared, and 5 mmol / L sodium dihydrogen phosphate buffer was added. NaOH was added to adjust the pH. The reaction was carried out for 60 min under the conditions of catalyst dosage of 2 g / L, ozone inlet concentration and inlet rate.

[0032] In this embodiment, the factors affecting the ozone oxidation catalyzed by the ozone catalyst were investigated:

[0033] 1. Effect of pH

[0034] Under the conditions of ozone concentration of 25 mg / L, air inlet rate of 0.2 L / min, and hydraulic retention time of 2 h, experiments were conducted at initial pH values ​​of 6, 7, 8, 9, and 10, respectively. The COD removal rates were 36.28%, 50.24%, 53.03%, 47.45%, and 44.65%, respectively. It can be seen that the ozone catalyst in this embodiment has good catalytic efficiency at an initial pH of 8.

[0035] 2. Hydraulic Retention Time (HRT)

[0036] Under the conditions of ozone concentration of 25 mg / L, air inlet rate of 0.2 L / min, and pH = 8, experiments were conducted at hydraulic retention times of 0.5 h, 1 h, 1.5 h, and 2 h, respectively. The COD removal rates were 44.65%, 47.45%, 55.82%, and 55.88%, respectively. It can be seen that the ozone catalyst in this embodiment has good catalytic efficiency at an HRT of 1.5 h.

[0037] 3. Intake rate

[0038] Under the conditions of ozone concentration of 25 mg / L, pH = 8, and hydraulic retention time of 1.5 h, experiments were conducted at inlet air rates of 0.1 L / min, 0.2 L / min, 0.3 L / min, and 0.4 L / min, respectively. The COD removal rates were 50.24%, 55.82%, 55.90%, and 55.84%, respectively. It can be seen that the ozone catalyst in this embodiment has good catalytic efficiency at an inlet air rate of 0.2 L / min.

[0039] 4. Ozone flow rate

[0040] Under the conditions of pH=8, air inlet rate 0.2L / min, and hydraulic retention time 1.5h, experiments were conducted at ozone flow rates of 5mg / L, 15mg / L, 25mg / L, 35mg / L, and 45mg / L, respectively. The COD removal rates were 27.91%, 33.49%, 55.82%, 58.64%, and 58.47%, respectively. It can be seen that the ozone catalyst in this embodiment has good catalytic efficiency at an ozone concentration of 35mg / L.

[0041] The absorbance of raw water and wastewater after reaction under ozone alone and catalytic ozone conditions was measured using an ultraviolet spectrophotometer at a wavelength of 254 nm. The measurement results are as follows: Figure 1 As shown, the ozone catalyst of the present invention has a significantly improved catalytic effect compared with ozone catalysis alone, indicating that the ozone catalyst of this embodiment has a positive effect on catalyzing ozone oxidation.

[0042] The Fe ions dissolved from the catalyst in this embodiment were detected, and the results are as follows: Figure 2 As shown, the Fe ion dissolution is less than 0.08 mg / L, which is less than the surface water quality standard of 0.3 mg / L, and it does not increase after 10 minutes. This indicates that the ozone catalyst in this embodiment has a small amount of Fe ion dissolution, which helps to improve the quality of the effluent.

[0043] The Mn ions dissolved from the catalyst in this embodiment were detected, and the results are as follows: Figure 3 As shown, the dissolution of Mn ions is less than 0.03 mg / L, which is less than the surface water quality standard of 0.1 mg / L, and it does not increase after 10 minutes. This indicates that the dissolution of Mn ions by the ozone catalyst in this embodiment is small, which helps to improve the quality of the effluent.

[0044] This invention is not limited to the preferred embodiments described above. Anyone can derive other forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for preparing an ozone catalyst, characterized in that: The following steps are involved: S1. Take nitrates of trivalent iron and divalent manganese and fully dissolve them in water to obtain a mixed solution; S2, adding anhydrous citric acid and γ-Al2O3 to the obtained mixed solution, heating and fully stirring to obtain a sol precursor; S3, drying and calcining the obtained sol precursor to obtain the ozone catalyst of the present invention.

2. The method for preparing an ozone catalyst according to claim 1, characterized in that: The ferric nitrate is ferric nitrate nonahydrate, and the manganese nitrate is manganese nitrate tetrahydrate.

3. The method for preparing an ozone catalyst according to claim 1, characterized in that: In the S1-S2, the molar ratio of ferric nitrate, manganese nitrate, anhydrous citric acid and γ-Al2O3 is 1:3-8:1-5:5-10.

4. The method for preparing an ozone catalyst according to claim 1, characterized in that: In the S2, the stirring temperature in the water bath is 60-80°C, the stirring time is 1-3h, and the stirring intensity is 100-200rpm.

5. The method for preparing an ozone catalyst according to claim 1, characterized in that: In the above-mentioned S3, the drying temperature is 105-120° C. and the drying time is 2-6 hours.

6. The method for preparing an ozone catalyst according to claim 1, characterized in that: In the above-mentioned S3, calcination is carried out in a tubular furnace, the atmosphere during calcination is air, and the air flow rate is 0.5-1.0 L / min.

7. The method for preparing an ozone catalyst according to claim 6, characterized in that: The calcination temperature is 500-600°C, and the calcination time is 4-8h.

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

9. The use of the ozone catalyst according to claim 8, characterized in that: The mass ratio of the dosage of the ozone catalyst to the refractory COD in the sewage is 30-40:1, the initial pH is 8, the hydraulic retention time is 1.5h, the ozone inlet concentration is 35mg / L, and the ozone inlet rate is 0.2L / min.

10. The use of the ozone catalyst according to claim 9, characterized in that: The sewage depth The removal rate of refractory COD in the treatment can reach 58.64% in 60 minutes, and the amount of iron ion dissolved is less than 0.08 mg / L. The amount of manganese ion dissolved is less than 0.03 mg / L.

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