A (Fe, Mn) Al2O4 catalyst material capable of simultaneously strengthening adsorption and decomposition of ozone and capable of magnetic separation, and a preparation method and application thereof

Abstract

The application relates to a (Fe, Mn) Al2O4 material capable of simultaneously strengthening adsorption and decomposing ozone and capable of magnetic separation and a preparation method and application thereof, and the process is as follows: Al2O3 is added to a NaOH solution, stirred, transferred into a PTFE hydrothermal reactor, and subjected to hydrothermal reaction in an oven. The obtained NaAlO2 powder is dissolved in deionized water, hydrochloric acid is added, and stirring is uniformly carried out, and the solution is used after being changed from turbidity to clarity, and is marked as A solution. Iron nitrate, manganese nitrate and deionized water are mixed, and are marked as B solution. The AB solution is mixed, ammonia water is added dropwise until the pH value is 10-11, and stirring is uniformly carried out. Then, the solution is transferred into the PTFE hydrothermal reactor, and subjected to hydrothermal reaction in the oven. After reaction, the material is centrifuged, washed, dried, and heated to obtain the (Fe, Mn) Al2O4 material. The preparation method is simple, the cost is low, the prepared material can simultaneously strengthen adsorption and decompose ozone to generate free radicals, rapidly degrade organic pollutants, and can be separated and fixed through magnetism after completing catalytic ozone oxidation of pollutants, secondary pollution is avoided, and the material can be applied to degradation of organic pollutants in tap water or municipal sewage.

Description

Technical Field

[0001] This invention relates to material preparation and chemical catalytic decomposition technology, specifically a catalyst for the efficient degradation of organic pollutants by ozone, its preparation method, and its application. This catalyst can simultaneously enhance the adsorption and decomposition of ozone-degraded organic matter and can magnetically separate the organic matter after degradation. Background Technology

[0002] In recent years, emerging organic pollutants such as antibiotics have been frequently detected in aquatic environments, posing a serious threat to aquatic organisms and aquatic products. The continuous input of these emerging pollutants into the environment leads to their rapid accumulation in water, causing potential and irreversible harm to humans through the food chain. Antibiotics in the aquatic environment mainly originate from urban sewage, hospital wastewater, reclaimed wastewater, and wastewater discharged from the pharmaceutical industry; most are organic pollutants that are difficult to biodegrade. Therefore, developing a technology to effectively remove or decompose organic pollutants in tap water or municipal wastewater to eliminate their harm to humans and other organisms has become an urgent problem to solve. Currently, the main methods for degrading and treating emerging organic pollutants in water include conventional water treatment technologies, activated carbon adsorption, chemical oxidation, and membrane separation.

[0003] Ozone oxidation is a type of chemical oxidation method, and it is a common and effective way to remove emerging organic pollutants from water bodies. However, ozone oxidation alone is selective, only degrading and removing certain organic compounds that are easily oxidized by ozone. In contrast, using a catalyst to catalyze ozone to generate free radicals, such as hydroxyl radicals, can efficiently degrade the vast majority of emerging organic pollutants in water bodies.

[0004] The long-term, high-efficiency, and stable treatment capacity of ozone catalytic oxidation technology largely depends on the selected catalyst material. In traditional catalyst applications, we often face several challenges and limitations. First, catalysts are difficult to recover after the reaction, which not only wastes resources but may also pollute the environment due to catalyst loss. Second, some catalysts have limited catalytic activity and may only achieve optimal results under harsher conditions, undoubtedly increasing production costs and energy consumption. Furthermore, the limited adsorption capacity of catalysts for ozone prevents them from achieving efficient catalytic oxidation at low concentrations. These shortcomings significantly limit their practical application. Therefore, it is essential to seek a catalyst with good catalytic properties for the efficient degradation of organic pollutants using ozone. Summary of the Invention

[0005] The purpose of this invention is to provide a simple and easy-to-operate method for preparing (Fe,Mn)Al2O4 materials that can simultaneously enhance the adsorption and decomposition of ozone and can be magnetically separated.

[0006] The mechanism of ozone decomposition by traditional iron oxides or manganese oxides is as follows: ozone combines with surface hydroxyl groups on the metal sites of the oxides, gaining an electron, and then decomposes, simultaneously increasing the valence state of the metal sites. The mechanism of ozone decomposition by traditional alumina is that ozone is adsorbed onto the metal sites (Lewis acid sites) on the aluminum surface and then decomposed. However, both of these materials have the following problems when decomposing ozone individually: the valence state of traditional iron oxides or manganese oxides, after increasing, cannot be reduced in time to continue catalyzing ozone decomposition. Furthermore, alumina alone has a relatively dense structure, with too little exposed metal activity on its surface.

[0007] The (Fe,Mn)Al2O4 catalytic material invented in this patent perfectly solves the shortcomings of the aforementioned materials in ozone decomposition. When the three metals coexist in the crystal, during ozone decomposition, the electrons lost by iron can be replenished by manganese. The tetravalent manganese formed after losing electrons has enhanced self-oxidation ability and can gain electrons by oxidizing pollutants in water, thus allowing the iron-manganese oxide to gain more electrons overall for ozone decomposition. At the same time, due to the presence of iron and manganese in the crystal structure, the Al is no longer restricted by the regularly grown Al-O bonds, thus providing more Al sites for ozone adsorption and decomposition. Furthermore, the ozone adsorbed on the Al sites can also be decomposed with the assistance of the surrounding iron-manganese sites. Therefore, the (Fe,Mn)Al2O4 catalytic material can significantly improve the overall ozone adsorption and decomposition capacity.

[0008] This method employs a two-step hydrothermal process to prepare (Fe,Mn)Al₂O₄. The preparation method is simple and operates under mild conditions, possessing three functions: ozone adsorption, rapid ozone decomposition to generate free radicals for pollutant degradation, and easy catalyst separation and recovery. The (Fe,Mn)Al₂O₄ catalytic material obtained through this method can be applied to the efficient degradation of organic pollutants in tap water or municipal wastewater using ozone catalysis.

[0009] To achieve the above objectives, this invention proposes a simple and easy-to-operate method for preparing a (Fe,Mn)Al2O4 catalytic material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable. This method is achieved through the following technical solution: The preparation method includes the following process steps:

[0010] S1: Add Al2O3 to NaOH solution and stir magnetically until homogeneous; transfer the resulting mixed solution to a PTFE hydrothermal reactor and carry out a hydrothermal reaction in an oven at a certain temperature;

[0011] S2: After the suspension is heated, it is taken out and allowed to cool naturally to room temperature. Then, it is centrifuged to separate the solid and liquid components. The separated solid components are washed several times with deionized water and then dried in a vacuum drying oven to obtain NaAlO2 powder.

[0012] S3: Add the obtained NaAlO2 powder to deionized water, then add hydrochloric acid and stir. After the solution changes from turbid to clear, set it aside and label it as solution A; mix and dissolve ferric nitrate and manganese nitrate with deionized water evenly and label it as solution B.

[0013] S4: After mixing the AB solutions, gradually add ammonia water until the pH value is maintained at 10-11, then stir for a period of time; then transfer the solution to a PTFE hydrothermal reactor and carry out the hydrothermal reaction at a certain temperature in an oven;

[0014] S5: After the suspension was removed from the heating process, it was allowed to cool naturally to room temperature and then centrifuged to separate the solid and liquid components. The separated solid components were dried in a vacuum drying oven and then heated in a muffle furnace to completely dehydrate and crystallize the product, thus successfully preparing (Fe,Mn)Al2O4 material.

[0015] Preferably, the concentration of the NaOH solution in step S1 is 10 mol / L; the ratio of NaOH solution to Al2O3 in step S1 is 1 ml: 20.4 mg.

[0016] Preferably, the hydrothermal temperature in step S1 is 180-190℃ and the reaction time is 30-35h; the hydrothermal temperature in step S4 is 180-190℃ and the reaction time is 7-10h.

[0017] Preferably, the molar ratio of NaAlO2 solution to hydrochloric acid solution in step S3 is 1:1; the stirring time after adding hydrochloric acid solution to NaAlO2 solution is 8-10h.

[0018] Preferably, the centrifugation conditions in steps S2 and S5 are 12,000 rpm for 5 minutes, followed by multiple water washes; the magnetic stirring speed is 500-700 rpm.

[0019] Preferably, the concentrations of ferric nitrate and manganese nitrate in the mixed solution in step S3 are both 0.1 mol / L.

[0020] Preferably, the drying time of the (Fe,Mn)Al2O4 suspension at 60-70℃ in step S2 is 10-12 h.

[0021] Preferably, the muffle furnace calcination conditions in step S5 are calcination at 550-600℃ for 5-8 hours followed by natural cooling.

[0022] This invention also proposes a (Fe,Mn)Al2O4 catalyst material that can simultaneously enhance the adsorption and decomposition of ozone and can be magnetically separated, which is prepared using the aforementioned method.

[0023] This invention also proposes the application of a (Fe,Mn)Al2O4 catalyst material, as described above, which can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable, in the efficient degradation of organic pollutants by ozone. The (Fe,Mn)Al2O4 catalyst material is used to catalyze the efficient degradation of organic pollutants by ozone, wherein Fe and Mn provide catalytic active sites, and Al is responsible for adsorbing ozone. After the reaction, the (Fe,Mn)Al2O4 is magnetic, which can achieve efficient separation from the reaction solution.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] a. The (Fe,Mn)Al2O4 catalytic material prepared in this invention is superior to commercial Al2O3, commercial Fe2O3 and commercial MnO2 materials in catalytic ozone degradation of organic pollutants.

[0026] b. The (Fe,Mn)Al2O4 catalytic material prepared in this invention has a strong adsorption capacity for ozone, which further enhances its activity in the degradation process, and its performance in degrading pollutants is superior to that of conventional catalysts.

[0027] c. The (Fe,Mn)Al2O4 catalytic material prepared by this invention is magnetic, which makes the catalyst easy to recover and avoids the loss of catalyst and pollution to the environment. Attached Figure Description

[0028] Figure 1 The image shows a scanning electron microscope (SEM) image of the (Fe,Mn)Al2O4 catalytic material.

[0029] Figure 2 Elemental composition analysis (EDS) diagram of (Fe,Mn)Al2O4 catalytic material;

[0030] Figure 3 The X-ray diffraction (XRD) pattern of the (Fe,Mn)Al2O4 catalytic material is shown.

[0031] Figure 4 This is an ATZ efficiency diagram for the degradation of one pollutant in organic pollutants according to the present invention;

[0032] Figure 5 This is a diagram showing the ozone concentration at the outlet during the ATZ degradation process of this invention. Detailed Implementation

[0033] The following detailed embodiments further illustrate the present invention, but should not be construed as limiting the invention. Any simple modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from its spirit and essence are within the scope of the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0034] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Example 1:

[0035] A method for preparing a (Fe,Mn)Al2O4 material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable includes the following steps:

[0036] 1.02 g of Al₂O₃ was added to 50 mL of 10 M NaOH solution and magnetically stirred for 2 h. The mixture was then transferred to a PTFE hydrothermal reactor and hydrothermally heated in an oven at 190 °C for 35 h. After cooling, the obtained NaAlO₂ was washed several times with deionized water and dried at 80 °C for 12 h to obtain NaAlO₂ powder. 0.82 g of NaAlO₂ powder was then added to 50 mL of water, followed by the addition of an equimolar amount of hydrochloric acid and stirring for 8 h. The solution was cleared and designated as solution A. 0.1 mol / L ferric nitrate and manganese nitrate were dissolved in 100 mL of deionized water and labeled as solution B. Solutions A and B were mixed, and ammonia was gradually added dropwise until the pH was maintained at 10–11, with stirring for approximately 30 min. The solution was then transferred to a PTFE hydrothermal reactor and hydrothermally heated in an oven at 180 °C for 7 h. Subsequently, the material was centrifuged and washed, then dried at 60°C for 10 hours, and then heated in a muffle furnace at 550°C to dehydrate and crystallize the product for 5 hours. Example 2:

[0037] The difference between this embodiment and Example 1 is that the concentrations of ferric nitrate and manganese nitrate are both 0.2 mol / L, while the rest is the same as in Example 1. Example 3:

[0038] This embodiment is an application of the (Fe,Mn)Al2O4 catalyst material used in Example 1 for the efficient degradation of organic pollutants by ozone, which is applied to the degradation of organic pollutants in tap water or municipal sewage.

[0039] The invention was verified using the following experiments:

[0040] Experiment 1: This experiment demonstrates a method for preparing a (Fe,Mn)Al2O4 catalytic material, specifically carried out according to the following steps:

[0041] (Fe,Mn)Al₂O₄ was prepared using a two-step hydrothermal method. First, 1.02 g of Al₂O₃ was added to 50 mL of 10 M NaOH solution and magnetically stirred for 2 h. The mixture was then transferred to a PTFE hydrothermal reactor and hydrothermally heated in an oven at 190 °C for 35 h. After cooling, the obtained NaAlO₂ was washed several times with deionized water and dried at 80 °C for 12 h to obtain NaAlO₂ powder. Subsequently, 0.82 g of NaAlO₂ powder was added to 50 mL of deionized water, and an equimolar amount of hydrochloric acid was added and stirred for 8 h until the solution changed from turbid to clear. This solution was then designated as solution A. 0.1 M ferric nitrate and 0.1 M manganese nitrate were dissolved uniformly in 100 mL of deionized water and designated as solution B. After mixing solutions A and B, ammonia was gradually added dropwise until the pH value was maintained at 10–11, and the mixture was stirred for approximately 30 min. The solution was then transferred to a PTFE hydrothermal reactor and hydrothermally heated in an oven at 180 °C for 7 h. Subsequently, the material was centrifuged and washed, then dried at 60℃ for 10 h, and then heated in a muffle furnace at 550℃ for 5 h to dehydrate and crystallize, thus successfully preparing (Fe,Mn)Al2O4 material. SEM images are shown below. Figure 1 As shown, Figure 2 The elemental composition analysis diagram of the catalyst material shows that the elemental proportion of O is 58.53%, Al is 15.20%, Mn is 12.57%, and Fe is 13.69%; XRD pattern ( Figure 3 The results show that the prepared (Fe,Mn)Al2O4 material has a high degree of crystallinity.

[0042] Experiment 2: This experiment simulates the application of a (Fe,Mn)Al2O4 catalyst to the efficient degradation of atrazine (ATZ), an organic pollutant, using ozone catalysis. ATZ was dissolved in 1 L of deionized water to a concentration of 5 mg / L and then added to the ozone catalytic reactor. The (Fe,Mn)Al2O4 catalyst prepared in Experiment 1 was then added to the solution in the ozone catalytic reactor, with a catalyst dosage of 0.03 g / L and a total dosage of 30 mg. Ozone was continuously introduced into the reactor, and the ozone concentration was measured at the reactor outlet. Samples of the simulated wastewater were taken at regular intervals to monitor the ATZ concentration. Figure 4 In the figure, the zigzag lines show the remaining concentration of ATZ without catalyst, the remaining concentration of ATZ with commercial Fe2O3 of the same catalyst concentration, the remaining concentration of ATZ with commercial Al2O3 of the same catalyst concentration, the remaining concentration of ATZ with commercial MnO2 of the same catalyst concentration, and the remaining concentration of ATZ with (Fe,Mn)Al2O4 catalyst material prepared in Example 1. Figure 4The results showed that after a reaction time of 30 minutes, ozone oxidized 52.1% of ATZ without a catalyst, Fe2O3 catalyzed ozone oxidized 62.2% of ATZ, Al2O3 catalyzed ozone oxidized 55.9% of ATZ, and MnO2 catalyzed ozone oxidized 68.1% of ATZ. The (Fe,Mn)Al2O4 catalyst prepared in Example 1 catalyzed the degradation of over 98% of ATZ within 5 minutes. Figure 5 In the figure, the zigzag lines respectively show the ozone outlet concentration without catalyst, the ozone outlet concentration with commercial Fe2O3 with the same catalyst concentration, the ozone outlet concentration with commercial Al2O3 with the same catalyst concentration, the ozone outlet concentration with commercial MnO2 with the same catalyst concentration, and the ozone outlet concentration with (Fe,Mn)Al2O4 catalyst material prepared in Example 1. Figure 5 The results show that the (Fe,Mn)Al2O4 catalytic material can catalyze the decomposition of ozone to generate free radicals.

Claims

1. A method for preparing a (Fe,Mn)Al2O4 catalyst material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable, characterized in that, The preparation of (Fe,Mn)Al2O4 using a two-step hydrothermal method includes the following steps: S1: Add Al2O3 to NaOH solution and stir magnetically until homogeneous; transfer the resulting mixed solution to a PTFE hydrothermal reactor and carry out a hydrothermal reaction in an oven at a certain temperature; S2: After the suspension is heated, it is taken out and allowed to cool naturally to room temperature. Then, it is centrifuged to separate the solid and liquid components. The separated solid components are washed several times with deionized water and then dried in a vacuum drying oven to obtain NaAlO2 powder. S3: Add the obtained NaAlO2 powder to deionized water, then add hydrochloric acid and stir. After the solution changes from turbid to clear, set it aside and label it as solution A; mix and dissolve ferric nitrate and manganese nitrate with deionized water evenly and label it as solution B. S4: After mixing the AB solutions, gradually add ammonia water until the pH value is maintained at 10-11, then stir for a period of time; The solution was then transferred to a PTFE hydrothermal reactor and subjected to a hydrothermal reaction at a certain temperature in an oven. S5: After the suspension was removed from the heating process, it was allowed to cool naturally to room temperature and then centrifuged to separate the solid and liquid components. The separated solid components were dried in a vacuum drying oven and then heated in a muffle furnace to completely dehydrate and crystallize the product, thus preparing the (Fe,Mn)Al2O4 catalyst material.

2. The method for preparing a (Fe,Mn)Al2O4 catalyst material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable according to claim 1, characterized in that, The concentration of the NaOH solution mentioned in step S1 is 10 mol / L; the ratio of NaOH solution to Al2O3 used in step S1 is 1 ml: 20.4 mg.

3. The preparation method of a (Fe,Mn)Al2O4 catalyst material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable according to claim 1, characterized in that, In step S1, the hydrothermal temperature is 180-190℃ and the reaction time is 30-35h; in step S4, the hydrothermal temperature is 180-190℃ and the reaction time is 7-10h.

4. The preparation method of a (Fe,Mn)Al2O4 catalyst material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable according to claim 1, characterized in that, The molar ratio of NaAlO2 solution and hydrochloric acid solution in step S3 is 1:1; the stirring time after adding hydrochloric acid solution to NaAlO2 solution is 8-10h.

5. The preparation method of a (Fe,Mn)Al2O4 catalyst material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable according to claim 1, characterized in that, In steps S2 and S5, the centrifugation conditions are 12,000 rpm for 5 minutes, followed by multiple water washes; the magnetic stirring speed is 500-700 rpm.

6. A method for preparing a (Fe,Mn)Al2O4 catalyst material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable, as described in claim 1, characterized in that, In step S3, the concentrations of both ferric nitrate and manganese nitrate in the mixed solution are 0.1 mol / L.

7. The preparation method of a (Fe,Mn)Al2O4 catalyst material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable according to claim 1, characterized in that, In step S2, the (Fe,Mn)Al2O4 suspension is dried at 60-70℃ for 10-12 hours.

8. The preparation method of a (Fe,Mn)Al2O4 catalyst material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable according to claim 1, characterized in that, In step S5, the muffle furnace calcination conditions are calcination at 550-600℃ for 5-8 hours followed by natural cooling.

9. A (Fe,Mn)Al2O4 catalyst material that can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. The application of the (Fe,Mn)Al2O4 catalyst material as described in claim 9, which can simultaneously enhance the adsorption and decomposition of ozone and is magnetically separable, in the efficient degradation of organic pollutants by catalytic ozone, characterized in that, (Fe,Mn)Al2O4 catalytic material is used to catalyze the efficient degradation of organic pollutants by ozone. Fe and Mn provide catalytic active sites, while Al is responsible for adsorbing ozone. After the reaction, (Fe,Mn)Al2O4 is magnetic and can be efficiently separated from the reaction solution.

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