Fe3O4 composite catalyst as well as preparation method and application thereof

Abstract

The invention discloses a Fe3O4 composite catalyst and a preparation method and application thereof, and relates to the technical field of catalysts, the Fe3O4 composite catalyst comprises Fe3O4, ferrous oxide, a transition metal oxide and a porous carrier, the transition metal oxide accounts for 1-10% of the total mass, and the porous carrier accounts for 65-85% of the total mass; the porous carrier is a functional carrier subjected to internal doping modification treatment and external functionalization treatment; in the internal doping modification treatment, metal or nonmetal is adopted to act on a bulk phase or a near-surface deep layer of the porous carrier; the external functionalization treatment is that a polymer chain is grafted on the surface layer of the porous carrier. The sewage treatment device has the effects of improving the sewage treatment efficiency and reducing the sewage treatment cost.

Description

Technical Field

[0001] The present application relates to the field of catalyst technology, and in particular to an Fe3O4 composite catalyst and a preparation method and application thereof. Background Art

[0002] High-salt and high-COD wastewater treatment refers to the process of treating wastewater containing high salt concentrations and high chemical oxygen demand to meet discharge standards or reuse requirements.

[0003] Since high-salt environments can dehydrate microbial cells, resulting in reduced intracellular enzyme activity, affecting microbial metabolism and growth, and thus inhibiting the effectiveness of biological treatment processes commonly used in wastewater treatment. To address this problem, it is necessary to use special salt-tolerant microorganisms or domesticate microorganisms, but this increases the complexity and cost of the treatment process. High-COD wastewater often contains a large amount of difficult-to-degrade organic matter, such as polycyclic aromatic hydrocarbons and heterocyclic compounds, which are difficult to completely decompose using traditional treatment methods. It may be necessary to use advanced oxidation technology, activated carbon adsorption and other methods, but these methods have high operating costs and large equipment investments.

[0004] Existing technologies often struggle to simultaneously meet the treatment requirements for both high-salinity and high-COD wastewater, necessitating the use of a combination of multiple treatment processes. This, however, can significantly increase operational and management complexity, extending the treatment cycle. In practice, a single catalyst suitable for treating high-salinity, high-COD wastewater is not readily available, and the time and cost associated with treating this wastewater remain high, requiring further improvement. Summary of the Invention

[0005] In view of this, the first object of this application is to provide an Fe3O4 composite catalyst to achieve the purpose of improving sewage treatment efficiency and reducing treatment costs. The specific scheme is as follows: A Fe3O4 composite catalyst comprises Fe3O4, ferrous oxide, a transition metal oxide and a porous carrier, wherein the transition metal oxide accounts for 1-10% of the total mass and the porous carrier accounts for 65-85% of the total mass; the porous carrier is a functional carrier that has been subjected to internal doping modification treatment and external functionalization treatment; the internal doping modification treatment is the use of metal or non-metal acting on the bulk phase or deep layer near the surface of the porous carrier; the external functionalization treatment is the use of polymer chains grafted to the surface layer of the porous carrier.

[0006] Preferably, the transition metal oxide is manganese oxide, copper oxide or cobalt oxide.

[0007] Preferably: the functional carrier is modified activated carbon or modified zeolite; the specific surface area S of the modified activated carbon and the modified zeolite is bet ≥800m² / g.

[0008] Preferably, the functional carrier is modified activated carbon, and the preparation method of the modified activated carbon comprises the following steps: Step 1: Raw material treatment: washing the activated carbon with deionized water and drying the activated carbon at 80°C until dry for later use; Step 2: Doping modification: urea and activated carbon were mixed in a mass ratio of 10:2.8-3.2, deionized water was added and stirred to obtain an activated carbon solution with a concentration of 1 g / ml, and the activated carbon solution was heated in a water bath at 58-62°C for 2-3 hours, and then pre-dried, calcined, cooled, washed, and post-dried to obtain nitrogen-doped activated carbon; Step ③ Functionalization treatment: The nitrogen-doped activated carbon was added to concentrated nitric acid and stirred evenly to obtain a doping solution with a concentration of 0.5 g / ml. The solution was heated in a water bath at 78-82°C and stirred under reflux for 4-5 hours. After the reaction was completed, the solution was cooled and washed with deionized water and dried at 78-82°C for 10-12 hours to obtain modified activated carbon that had undergone internal doping modification treatment and external functionalization treatment.

[0009] Preferably: in step ②, the pre-drying temperature is 78-82°C and the time is 8 hours; the calcination is to control the gas flow rate to be greater than or equal to 50 mL / min in a nitrogen atmosphere to heat to 500°C, control the heating rate to be 5°C / min, and keep it at 500°C for 2 hours; the post-drying temperature is 78-82°C and the time is 11-13 hours.

[0010] Preferably, the functional carrier is a modified zeolite, and the preparation method of the modified zeolite comprises the following steps: Step 1: Raw material treatment: zeolite is placed in deionized water, stirred and the supernatant is removed repeatedly to obtain clean zeolite, and then the clean zeolite is immersed in a 1 mol / L hydrochloric acid solution for 1.5-2.5 hours, controlling the solid-liquid ratio to 1:5. Finally, the pretreated zeolite is obtained after washing with deionized water and drying. Step 2: Doping modification: dissolving titanium tetrachloride in anhydrous ethanol and stirring to obtain a 0.1 g / L titanium tetrachloride ethanol solution, then placing the pretreated zeolite into the titanium tetrachloride ethanol solution and heating it in a water bath at 58-62°C for 3.5-5 hours, controlling the mass ratio of titanium tetrachloride to pretreated zeolite to be 1:9-11, and finally filtering, washing with anhydrous ethanol, pre-drying, calcining, and cooling in sequence to obtain titanium-doped zeolite; Step ③ Functionalization treatment: The titanium-doped zeolite is put into a toluene solution of 3-aminopropyltriethoxysilane, and the amount ratio of titanium-doped zeolite, 3-aminopropyltriethoxysilane and toluene is controlled to be 25:1.95-2.05:50. Under the protection of an inert gas atmosphere, the temperature is controlled to 78-82°C and stirred and refluxed for 6-7 hours. After the reaction is completed, it is cooled to room temperature, 3-aminopropyltriethoxysilane is removed, washed with anhydrous ethanol, and dried at 78-82°C for 8-9 hours to obtain a modified zeolite that has undergone internal doping modification treatment and external functionalization treatment.

[0011] Preferably, in step ②, the pre-drying temperature is 78-82° C. and the time is 6 h; the calcination is carried out in an air atmosphere at a heating rate of 5° C. / min to 500° C. and then kept at 500° C. for 3 h.

[0012] A second object of the present invention is to provide a method for preparing an Fe3O4 composite catalyst, which is used to prepare the Fe3O4 composite catalyst as described above, comprising the following steps: Step 1, prepare a porous support, Fe3O4, ferrous oxide, transition metal oxide, polyvinyl alcohol and anhydrous ethanol; Step 2: adding polyvinyl alcohol into anhydrous ethanol and stirring to dissolve to obtain a polyvinyl alcohol ethanol solution with a concentration of 0.02 g / ml; Step 3: Fe3O4, ferrous oxide and transition metal oxide are mixed and stirred until uniform to obtain a mixed active material; Step 4: Mix the porous support with the mixed active material and polyvinyl alcohol ethanol solution, stir and react for 6-8 hours in an oil bath at 78-82°C, and after the reaction is completed, centrifuge, wash with ethanol and vacuum dry to obtain a Fe3O4 composite catalyst.

[0013] Preferably, in step 4, the centrifugal speed is 8000 r / min and the time is 10 min; the vacuum drying temperature is 105° C. and the time is 12 h.

[0014] The third object of the present invention is to provide an application of an Fe3O4 composite catalyst, including using the Fe3O4 composite catalyst as described above and applying it to the wastewater treatment coupled with ozone.

[0015] Through the above scheme, it can be seen that the present application provides a Fe3O4 composite catalyst and its preparation method and application. The Fe3O4 composite catalyst obtains a functional carrier by modifying the porous carrier through internal doping and external functionalization, thereby achieving the effect of significantly improving the electron transfer rate and catalytic activity, and making the functional carrier have the ability to effectively adsorb and bind pollutants, so that after being compounded with Fe3O4, ferrous oxide and transition metal oxides, it significantly improves the synergistic effect with ozone and improves the degradation efficiency of sewage. The preparation method of the Fe3O4 composite catalyst has the effects of convenient control and stable preparation, and is suitable for industrial production. The application of the Fe3O4 composite catalyst has the effect of significantly improving sewage treatment efficiency and reducing sewage treatment costs. DETAILED DESCRIPTION

[0016] The following will be a clear and complete description of the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0017] It should be mentioned that the mass ratio of Fe3O4, ferrous oxide and transition metal oxide in the Fe3O4 composite catalyst in the embodiment of the present application is 3:1:1.6. Of course, other ratios are also applicable to sewage treatment and will not be elaborated here.

[0018] The following is a detailed description of an Fe3O4 composite catalyst of the present application and its preparation method and application.

[0019] An Fe3O4 composite catalyst comprises Fe3O4, ferrous oxide, a transition metal oxide, and a porous support. The transition metal oxide accounts for 1-10% of the total mass, and the porous support accounts for 65-85% of the total mass. The porous support is a functionalized support that has undergone both internal doping and external functionalization. The internal doping treatment involves the application of metals or non-metals to the bulk or deep layers near the surface of the porous support. The external functionalization treatment involves the grafting of polymer chains onto the surface of the porous support.

[0020] It should be mentioned that the transition metal oxide in the embodiment of the present application is manganese oxide, copper oxide or cobalt oxide. The functional carrier is modified activated carbon or modified zeolite, and the specific surface area S of the modified activated carbon and the modified zeolite is bet ≥800m² / g.

[0021] When the functional carrier is modified activated carbon, the preparation method of the modified activated carbon comprises the following steps: Step 1: Raw material treatment: washing the activated carbon with deionized water and drying the activated carbon at 80°C until dry for later use; Step 2: Doping modification: urea and activated carbon were mixed in a mass ratio of 10:2.8-3.2, deionized water was added and stirred to obtain an activated carbon solution with a concentration of 1 g / ml, and the activated carbon solution was heated in a water bath at 58-62°C for 2-3 hours, and then pre-dried, calcined, cooled, washed, and post-dried to obtain nitrogen-doped activated carbon; Step ③ Functionalization treatment: The nitrogen-doped activated carbon was added to concentrated nitric acid and stirred evenly to obtain a doping solution with a concentration of 0.5 g / ml. The solution was heated in a water bath at 78-82°C and stirred under reflux for 4-5 hours. After the reaction was completed, the solution was cooled and washed with deionized water and dried at 78-82°C for 10-12 hours to obtain modified activated carbon that had undergone internal doping modification treatment and external functionalization treatment.

[0022] In step ②, the pre-drying temperature is 78-82°C for 8 hours. Calcination is performed by heating the sample to 500°C in a nitrogen atmosphere at a controlled gas flow rate of 50 mL / min, at a controlled heating rate of 5°C / min, and then maintaining the temperature at 500°C for 2 hours. Post-drying is performed at a temperature of 78-82°C for 11-13 hours.

[0023] When the functional carrier is a modified zeolite, the preparation method of the modified zeolite comprises the following steps: Step 1: Raw material treatment: zeolite is placed in deionized water, stirred and the supernatant is removed repeatedly to obtain clean zeolite, and then the clean zeolite is immersed in a 1 mol / L hydrochloric acid solution for 1.5-2.5 hours, controlling the solid-liquid ratio to 1:5. Finally, the pretreated zeolite is obtained after washing with deionized water and drying. Step 2: Doping modification: dissolving titanium tetrachloride in anhydrous ethanol and stirring to obtain a 0.1 g / L titanium tetrachloride ethanol solution, then placing the pretreated zeolite into the titanium tetrachloride ethanol solution and heating it in a water bath at 58-62°C for 3.5-5 hours, controlling the mass ratio of titanium tetrachloride to pretreated zeolite to be 1:9-11, and finally filtering, washing with anhydrous ethanol, pre-drying, calcining, and cooling in sequence to obtain titanium-doped zeolite; Step ③ Functionalization treatment: The titanium-doped zeolite is put into a toluene solution of 3-aminopropyltriethoxysilane, and the amount ratio of titanium-doped zeolite, 3-aminopropyltriethoxysilane and toluene is controlled to be 25:1.95-2.05:50. Under the protection of an inert gas atmosphere, the temperature is controlled to 78-82°C and stirred and refluxed for 6-7 hours. After the reaction is completed, it is cooled to room temperature, 3-aminopropyltriethoxysilane is removed, washed with anhydrous ethanol, and dried at 78-82°C for 8-9 hours to obtain a modified zeolite that has undergone internal doping modification treatment and external functionalization treatment.

[0024] In step ②, the pre-drying temperature is 78-82°C for 6 hours. The calcination is carried out in an air atmosphere by heating the temperature at a rate of 5°C / min to 500°C and then maintaining the temperature at 500°C for 3 hours.

[0025] A method for preparing an Fe3O4 composite catalyst, for preparing the Fe3O4 composite catalyst as described above, comprises the following steps: Step 1, prepare a porous support, Fe3O4, ferrous oxide, transition metal oxide, polyvinyl alcohol and anhydrous ethanol; Step 2: adding polyvinyl alcohol into anhydrous ethanol and stirring to dissolve to obtain a polyvinyl alcohol ethanol solution with a concentration of 0.02 g / ml; Step 3: Fe3O4, ferrous oxide and transition metal oxide are mixed and stirred until uniform to obtain a mixed active material; Step 4: Mix the porous carrier with the mixed active material and polyvinyl alcohol ethanol solution, stir and react for 6-8 hours in an oil bath at 78-82°C, and after the reaction is completed, centrifuge, wash with ethanol and vacuum dry at a speed of 8000 r / min for 10 minutes and a vacuum drying temperature of 105°C for 12 hours to obtain a Fe3O4 composite catalyst.

[0026] An application of an Fe3O4 composite catalyst comprises using the Fe3O4 composite catalyst as described above and applying it to wastewater treatment in combination with ozone.

[0027] Example 1 An Fe3O4 composite catalyst comprises Fe3O4, ferrous oxide, a transition metal oxide, and a porous support. The porous support accounts for 65% of the total mass. The porous support is a functionalized support that has undergone internal doping and modification treatments, and external functionalization. The internal doping and modification treatment involves the application of metals or non-metals to the bulk or deep layers near the surface of the porous support. The external functionalization treatment involves the grafting of polymer chains onto the surface of the porous support.

[0028] It should be mentioned that the transition metal oxide in the embodiment of the present application is manganese oxide. The functional carrier is modified activated carbon, and the modified activated carbon has a specific surface area S bet ≥800m² / g.

[0029] In the embodiment of the present application, the preparation method of modified activated carbon includes the following steps: Step 1: Raw material treatment: washing the activated carbon with deionized water and drying the activated carbon at 80°C until dry for later use; Step 2: Doping modification: urea and activated carbon were mixed in a mass ratio of 10:2.8, deionized water was added and stirred to obtain an activated carbon solution with a concentration of 1 g / ml. The activated carbon solution was heated in a water bath at 58°C for 2 h, and then pre-dried, calcined, cooled, washed, and post-dried to obtain nitrogen-doped activated carbon. Step ③ Functionalization treatment: The nitrogen-doped activated carbon was added to concentrated nitric acid and stirred evenly to obtain a doping solution with a concentration of 0.5 g / ml. The solution was heated in a water bath at 78°C and stirred under reflux for 4 h. After the reaction was completed, the solution was cooled and washed with deionized water and dried at 78°C for 10 h to obtain modified activated carbon that had undergone internal doping modification and external functionalization treatment.

[0030] In step ②, the pre-drying temperature was 78°C for 8 hours. Calcination was performed by heating the sample to 500°C in a nitrogen atmosphere at a controlled rate of 5°C / min with a gas flow rate of 50 mL / min, and then maintaining the temperature at 500°C for 2 hours. Post-drying was performed at 78°C for 11 hours.

[0031] A method for preparing an Fe3O4 composite catalyst, for preparing the Fe3O4 composite catalyst as described above, comprises the following steps: Step 1, prepare a porous support, Fe3O4, ferrous oxide, transition metal oxide, polyvinyl alcohol and anhydrous ethanol; Step 2: adding polyvinyl alcohol into anhydrous ethanol and stirring to dissolve to obtain a polyvinyl alcohol ethanol solution with a concentration of 0.02 g / ml; Step 3: Fe3O4, ferrous oxide and transition metal oxide are mixed and stirred until uniform to obtain a mixed active material; Step 4: Mix the porous carrier with the mixed active material and polyvinyl alcohol ethanol solution, stir and react for 6 hours in an oil bath at 78°C, and after the reaction is completed, centrifuge, wash with ethanol and vacuum dry at a speed of 8000 r / min for 10 minutes and a vacuum drying temperature of 105°C for 12 hours to obtain a Fe3O4 composite catalyst.

[0032] An application of an Fe3O4 composite catalyst comprises using the Fe3O4 composite catalyst as described above and applying it to wastewater treatment in combination with ozone.

[0033] Example 2 An Fe3O4 composite catalyst comprises Fe3O4, ferrous oxide, a transition metal oxide, and a porous support. The porous support accounts for 75% of the total mass. The porous support is a functional support that has undergone internal doping and modification treatments and external functionalization. The internal doping and modification treatment involves the application of metals or non-metals to the bulk or deep layers near the surface of the porous support. The external functionalization treatment involves the grafting of polymer chains onto the surface of the porous support.

[0034] It should be mentioned that the transition metal oxide in the embodiment of the present application is manganese oxide. The functional carrier is modified activated carbon, and the specific surface area S of the modified activated carbon is bet ≥800m² / g.

[0035] In the embodiment of the present application, the preparation method of modified activated carbon includes the following steps: Step 1: Raw material treatment: washing the activated carbon with deionized water and drying the activated carbon at 80°C until dry for later use; Step 2: Doping modification: urea and activated carbon were mixed in a mass ratio of 10:3, deionized water was added and stirred to obtain an activated carbon solution with a concentration of 1 g / ml. The activated carbon solution was heated in a water bath at 60°C for 2.5 h, and then pre-dried, calcined, cooled, washed, and post-dried to obtain nitrogen-doped activated carbon. Step ③ Functionalization treatment: The nitrogen-doped activated carbon was added to concentrated nitric acid and stirred evenly to obtain a doping solution with a concentration of 0.5 g / ml. The solution was heated in an 80°C water bath and stirred under reflux for 4-5 hours. After the reaction was completed, the solution was cooled and washed with deionized water and dried at 80°C for 11 hours to obtain modified activated carbon that had undergone internal doping modification and external functionalization treatment.

[0036] In step ②, the pre-drying temperature was 80°C for 8 hours. Calcination was performed by heating the sample to 500°C in a nitrogen atmosphere at a controlled gas flow rate of 50 mL / min, at a controlled heating rate of 5°C / min, and then maintaining the temperature at 500°C for 2 hours. Post-drying was performed at 80°C for 12 hours.

[0037] A method for preparing an Fe3O4 composite catalyst, for preparing the Fe3O4 composite catalyst as described above, comprises the following steps: Step 1, prepare a porous support, Fe3O4, ferrous oxide, transition metal oxide, polyvinyl alcohol and anhydrous ethanol; Step 2: adding polyvinyl alcohol into anhydrous ethanol and stirring to dissolve to obtain a polyvinyl alcohol ethanol solution with a concentration of 0.02 g / ml; Step 3: Fe3O4, ferrous oxide and transition metal oxide are mixed and stirred until uniform to obtain a mixed active material; Step 4: Mix the porous carrier with the mixed active material and polyvinyl alcohol ethanol solution, stir and react for 7 hours in an oil bath at 80°C, and after the reaction is completed, centrifuge, wash with ethanol and vacuum dry at a speed of 8000 r / min for 10 minutes and a vacuum drying temperature of 105°C for 12 hours to obtain a Fe3O4 composite catalyst.

[0038] An application of an Fe3O4 composite catalyst comprises using the Fe3O4 composite catalyst as described above and applying it to wastewater treatment in combination with ozone.

[0039] Example 3 An Fe3O4 composite catalyst comprises Fe3O4, ferrous oxide, a transition metal oxide, and a porous support. The porous support accounts for 85% of the total mass. The porous support is a functional support that has undergone internal doping and modification treatments and external functionalization. The internal doping and modification treatment involves the application of metals or non-metals to the bulk or deep layers near the surface of the porous support. The external functionalization treatment involves the grafting of polymer chains onto the surface of the porous support.

[0040] It should be mentioned that the transition metal oxide in the embodiment of the present application is manganese oxide. The functional carrier is modified activated carbon, and the specific surface area S of the modified activated carbon is bet ≥800m² / g.

[0041] In the embodiment of the present application, the preparation method of modified activated carbon includes the following steps: Step 1: Raw material treatment: washing the activated carbon with deionized water and drying the activated carbon at 80°C until dry for later use; Step 2: Doping modification: urea and activated carbon were mixed in a mass ratio of 10:3.2, deionized water was added and stirred to obtain an activated carbon solution with a concentration of 1 g / ml. The activated carbon solution was heated in a water bath at 62°C for 3 h, and then pre-dried, calcined, cooled, washed, and post-dried to obtain nitrogen-doped activated carbon. Step ③ Functionalization treatment: The nitrogen-doped activated carbon was added to concentrated nitric acid and stirred evenly to obtain a doping solution with a concentration of 0.5 g / ml. The solution was heated in a water bath at 82°C and stirred under reflux for 5 h. After the reaction was completed, the solution was cooled and washed with deionized water and dried at 82°C for 12 h to obtain modified activated carbon that had undergone internal doping modification and external functionalization treatment.

[0042] In step ②, the pre-drying temperature was 82°C for 8 hours. Calcination was performed by heating the sample to 500°C in a nitrogen atmosphere at a controlled rate of 5°C / min with a gas flow rate of 50 mL / min, and then maintaining the temperature at 500°C for 2 hours. Post-drying was performed at 82°C for 13 hours.

[0043] A method for preparing an Fe3O4 composite catalyst, for preparing the Fe3O4 composite catalyst as described above, comprises the following steps: Step 1, prepare a porous support, Fe3O4, ferrous oxide, transition metal oxide, polyvinyl alcohol and anhydrous ethanol; Step 2: adding polyvinyl alcohol into anhydrous ethanol and stirring to dissolve to obtain a polyvinyl alcohol ethanol solution with a concentration of 0.02 g / ml; Step 3: Fe3O4, ferrous oxide and transition metal oxide are mixed and stirred until uniform to obtain a mixed active material; Step 4: Mix the porous carrier with the mixed active material and polyvinyl alcohol ethanol solution, stir and react for 8 hours in an oil bath at 82°C, and after the reaction is completed, centrifuge, wash with ethanol and vacuum dry at a speed of 8000 r / min for 10 minutes and a vacuum drying temperature of 105°C for 12 hours to obtain an Fe3O4 composite catalyst.

[0044] An application of an Fe3O4 composite catalyst comprises using the Fe3O4 composite catalyst as described above and applying it to wastewater treatment in combination with ozone.

[0045] Example 4 An Fe3O4 composite catalyst comprises Fe3O4, ferrous oxide, a transition metal oxide, and a porous support. The porous support accounts for 65% of the total mass. The porous support is a functional support that has undergone internal doping and modification treatments, and external functionalization. The internal doping and modification treatment involves the application of metals or non-metals to the bulk or deep layers near the surface of the porous support. The external functionalization treatment involves the grafting of polymer chains onto the surface of the porous support.

[0046] It should be mentioned that the transition metal oxide in the embodiment of the present application is manganese oxide. The functional carrier is a modified zeolite, and the specific surface area S of the modified zeolite is bet ≥800m² / g.

[0047] In the embodiment of the present application, the preparation method of the modified zeolite comprises the following steps: Step 1: Raw material treatment: zeolite was placed in deionized water, stirred and the supernatant was removed repeatedly to obtain clean zeolite, and then the clean zeolite was immersed in a 1 mol / L hydrochloric acid solution for 1.5 hours, with the solid-liquid ratio controlled at 1:5. Finally, the pretreated zeolite was obtained after washing with deionized water and drying. Step 2: Doping modification: titanium tetrachloride was dissolved in anhydrous ethanol, and a 0.1 g / L titanium tetrachloride ethanol solution was obtained by stirring. The pretreated zeolite was then placed in the titanium tetrachloride ethanol solution and heated in a water bath at 58°C for 3.5 hours. The mass ratio of titanium tetrachloride to pretreated zeolite was controlled to be 1:9. Finally, the zeolite was filtered, washed with anhydrous ethanol, pre-dried, calcined, and cooled in sequence to obtain titanium-doped zeolite. Step ③ Functionalization treatment: The titanium-doped zeolite was put into a toluene solution of 3-aminopropyltriethoxysilane, and the amount ratio of titanium-doped zeolite, 3-aminopropyltriethoxysilane and toluene was controlled to be 25:1.95:50. Under the protection of an inert gas atmosphere, the temperature was controlled to 78°C and stirred and refluxed for 6 hours. After the reaction was completed, it was cooled to room temperature, 3-aminopropyltriethoxysilane was removed, washed with anhydrous ethanol and dried at 78°C for 8 hours to obtain a modified zeolite that had undergone internal doping modification treatment and external functionalization treatment.

[0048] In step ②, the pre-drying temperature is 78° C. for 6 hours. The calcination is carried out in an air atmosphere by heating the temperature to 500° C. at a rate of 5° C. / min and then maintaining the temperature at 500° C. for 3 hours.

[0049] A method for preparing an Fe3O4 composite catalyst, for preparing the Fe3O4 composite catalyst as described above, comprises the following steps: Step 1, prepare a porous support, Fe3O4, ferrous oxide, transition metal oxide, polyvinyl alcohol and anhydrous ethanol; Step 2: adding polyvinyl alcohol into anhydrous ethanol and stirring to dissolve to obtain a polyvinyl alcohol ethanol solution with a concentration of 0.02 g / ml; Step 3: Fe3O4, ferrous oxide and transition metal oxide are mixed and stirred until uniform to obtain a mixed active material; Step 4: Mix the porous carrier with the mixed active material and polyvinyl alcohol ethanol solution, stir and react for 6 hours in an oil bath at 78°C, and after the reaction is completed, centrifuge, wash with ethanol and vacuum dry at a speed of 8000 r / min for 10 minutes and a vacuum drying temperature of 105°C for 12 hours to obtain a Fe3O4 composite catalyst.

[0050] An application of an Fe3O4 composite catalyst comprises using the Fe3O4 composite catalyst as described above and applying it to wastewater treatment in combination with ozone.

[0051] Example 5 An Fe3O4 composite catalyst comprises Fe3O4, ferrous oxide, a transition metal oxide, and a porous support. The porous support accounts for 75% of the total mass. The porous support is a functional support that has undergone internal doping and modification treatments and external functionalization. The internal doping and modification treatment involves the application of metals or non-metals to the bulk or deep layers near the surface of the porous support. The external functionalization treatment involves the grafting of polymer chains onto the surface of the porous support.

[0052] It should be mentioned that the transition metal oxide in the embodiment of the present application is copper oxide. The functional carrier is a modified zeolite, and the specific surface area S of the modified zeolite is bet ≥800m² / g.

[0053] In the embodiment of the present application, the preparation method of the modified zeolite comprises the following steps: Step 1: Raw material treatment: zeolite is placed in deionized water, stirred and the supernatant is removed repeatedly to obtain clean zeolite, which is then immersed in a 1 mol / L hydrochloric acid solution for 2 hours, with a solid-liquid ratio of 1:5. Finally, the pretreated zeolite is obtained after washing with deionized water and drying. Step 2: Doping modification: titanium tetrachloride was dissolved in anhydrous ethanol, and a 0.1 g / L titanium tetrachloride ethanol solution was obtained by stirring. The pretreated zeolite was then placed in the titanium tetrachloride ethanol solution and heated in a water bath at 60°C for 4 hours. The mass ratio of titanium tetrachloride to pretreated zeolite was controlled to be 1:10. Finally, the zeolite was filtered, washed with anhydrous ethanol, pre-dried, calcined, and cooled in sequence to obtain titanium-doped zeolite. Step ③ Functionalization treatment: The titanium-doped zeolite was put into a toluene solution of 3-aminopropyltriethoxysilane, and the amount ratio of titanium-doped zeolite, 3-aminopropyltriethoxysilane and toluene was controlled to be 25:2:50. Under the protection of an inert gas atmosphere, the temperature was controlled to 80°C and stirred and refluxed for 6.5 hours. After the reaction was completed, it was cooled to room temperature, 3-aminopropyltriethoxysilane was removed, washed with anhydrous ethanol and dried at 80°C for 8.5 hours to obtain a modified zeolite that had undergone internal doping modification treatment and external functionalization treatment.

[0054] In step ②, the pre-drying temperature is 80° C. for 6 hours. The calcination is carried out in an air atmosphere by heating the temperature at a rate of 5° C. / min to 500° C. and then maintaining the temperature at 500° C. for 3 hours.

[0055] A method for preparing an Fe3O4 composite catalyst, for preparing the Fe3O4 composite catalyst as described above, comprises the following steps: Step 1, prepare a porous support, Fe3O4, ferrous oxide, transition metal oxide, polyvinyl alcohol and anhydrous ethanol; Step 2: adding polyvinyl alcohol into anhydrous ethanol and stirring to dissolve to obtain a polyvinyl alcohol ethanol solution with a concentration of 0.02 g / ml; Step 3: Fe3O4, ferrous oxide and transition metal oxide are mixed and stirred until uniform to obtain a mixed active material; Step 4: Mix the porous carrier with the mixed active material and polyvinyl alcohol ethanol solution, stir and react for 7 hours in an oil bath at 80°C, and after the reaction is completed, centrifuge, wash with ethanol and vacuum dry at a speed of 8000 r / min for 10 minutes and a vacuum drying temperature of 105°C for 12 hours to obtain a Fe3O4 composite catalyst.

[0056] An application of an Fe3O4 composite catalyst comprises using the Fe3O4 composite catalyst as described above and applying it to wastewater treatment in combination with ozone.

[0057] Example 6 An Fe3O4 composite catalyst comprises Fe3O4, ferrous oxide, a transition metal oxide, and a porous support. The porous support accounts for 85% of the total mass. The porous support is a functional support that has undergone internal doping and modification treatments and external functionalization. The internal doping and modification treatment involves the application of metals or non-metals to the bulk or deep layers near the surface of the porous support. The external functionalization treatment involves the grafting of polymer chains onto the surface of the porous support.

[0058] It should be mentioned that the transition metal oxide in the embodiment of the present application is cobalt oxide. The functional carrier is a modified zeolite, and the specific surface area S of the modified zeolite is bet ≥800m² / g.

[0059] In the embodiment of the present application, the preparation method of the modified zeolite comprises the following steps: Step 1: Raw material treatment: zeolite was placed in deionized water, stirred and the supernatant was removed repeatedly to obtain clean zeolite, and then the clean zeolite was immersed in a 1 mol / L hydrochloric acid solution for 2.5 hours, with the solid-liquid ratio controlled at 1:5. Finally, the pretreated zeolite was obtained after washing with deionized water and drying. Step 2: Doping modification: titanium tetrachloride was dissolved in anhydrous ethanol, and a 0.1 g / L titanium tetrachloride ethanol solution was obtained by stirring. The pretreated zeolite was then placed in the titanium tetrachloride ethanol solution and heated in a water bath at 62°C for 5 hours. The mass ratio of titanium tetrachloride to pretreated zeolite was controlled to be 1:11. Finally, the zeolite was filtered, washed with anhydrous ethanol, pre-dried, calcined, and cooled in sequence to obtain titanium-doped zeolite. Step ③ Functionalization treatment: The titanium-doped zeolite was put into a toluene solution of 3-aminopropyltriethoxysilane, and the amount ratio of titanium-doped zeolite, 3-aminopropyltriethoxysilane and toluene was controlled to be 25:2.05:50. Under the protection of an inert gas atmosphere, the temperature was controlled to 82°C and stirred and refluxed for 7 hours. After the reaction was completed, it was cooled to room temperature, 3-aminopropyltriethoxysilane was removed, washed with anhydrous ethanol and dried at 82°C for 9 hours to obtain a modified zeolite that had undergone internal doping modification treatment and external functionalization treatment.

[0060] In step ②, the pre-drying temperature is 82° C. for 6 hours. The calcination is carried out in an air atmosphere by heating the temperature to 500° C. at a rate of 5° C. / min and then maintaining the temperature at 500° C. for 3 hours.

[0061] A method for preparing an Fe3O4 composite catalyst, for preparing the Fe3O4 composite catalyst as described above, comprises the following steps: Step 1, prepare a porous support, Fe3O4, ferrous oxide, transition metal oxide, polyvinyl alcohol and anhydrous ethanol; Step 2: adding polyvinyl alcohol into anhydrous ethanol and stirring to dissolve to obtain a polyvinyl alcohol ethanol solution with a concentration of 0.02 g / ml; Step 3: Fe3O4, ferrous oxide and transition metal oxide are mixed and stirred until uniform to obtain a mixed active material; Step 4: Mix the porous carrier with the mixed active material and polyvinyl alcohol ethanol solution, stir and react for 8 hours under 82°C oil bath conditions, and after the reaction is completed, centrifuge, wash with ethanol and vacuum dry at a speed of 8000 r / min for 10 minutes and a vacuum drying temperature of 105°C for 12 hours to obtain a Fe3O4 composite catalyst.

[0062] An application of an Fe3O4 composite catalyst comprises using the Fe3O4 composite catalyst as described above and applying it to wastewater treatment in combination with ozone.

[0063] Comparative Example 1 Comparative Example 1 Compared with Example 2, the modified activated carbon in Comparative Example 1 has not been subjected to doping treatment.

[0064] Comparative Example 2 Comparative Example 2 Compared with Example 2, the modified activated carbon in Comparative Example 2 has not been subjected to functionalization treatment.

[0065] Comparative Example 3 Comparative Example 3 Compared with Example 2, the modified activated carbon was replaced by activated carbon in Comparative Example 3.

[0066] Comparative Example 4 Comparative Example 4 Compared with Example 4, the modified zeolite in Comparative Example 4 has not been doped.

[0067] Comparative Example 5 Comparative Example 5 Compared with Example 4, the modified zeolite in Comparative Example 5 has not been subjected to functionalization treatment.

[0068] Comparative Example 6 Comparative Example 6 Compared with Example 4, the comparative example 6 uses zeolite instead of modified zeolite.

[0069] Performance testing: 20g of each of the Fe3O4 composite catalysts obtained in Examples 1 to 6 and Comparative Examples 1 to 6 were divided into four groups, each containing 5g. 500ml of wastewater with a COD concentration of 1000mg / L was prepared for later use. A batch reactor was used, equipped with an ozone generator, with an ozone output of 50mg / h and a magnetic stirrer speed of 300r / min.

[0070] For each embodiment and comparative example, first add 5g of Fe3O4 composite catalyst to a beaker, start stirring to evenly disperse the catalyst, then introduce ozone, control the gas flow rate to 0.5L / min and time, sample 50mL at 0.5h, 1h, 2h, and 3h of the reaction, add excess Na2S2O3 solution to the sample, and terminate the reaction. After filtering through a 0.45μm filter membrane, the COD value of the filtrate is determined by the potassium dichromate method, and the test results are averaged. The results are shown in Table 1 below.

[0071] Table 1 Performance test results 0.5h removal rate (%) 1h removal rate (%) 2h removal rate (%) 3h removal rate (%) Example 1 36.2 56.8 73.5 83.9 Example 2 42.2 67.0 82.0 90.6 Example 3 34.3 51.3 69.5 82.1 Example 4 32.0 50.8 70.6 79.5 Example 5 38.4 59.7 76.1 85.3 Example 6 40.2 62.4 79.1 87.6 Comparative Example 1 26.3 42.9 57.4 67.5 Comparative Example 2 21.7 37.1 52.8 61.2 Comparative Example 3 16.5 26.3 36.1 45.0 Comparative Example 4 23.3 38.2 51.7 58.1 Comparative Example 5 18.0 32.6 45.4 56.2 Comparative Example 6 11.4 21.6 31.0 43.6 As can be seen from Table 1 above, the removal rate in the embodiment of the present application at 0.5h mainly depends on the functionalized adsorption group of the functional carrier, and due to the high adsorption capacity in Example 2 and Example 6, thereby enabling it to have excellent removal rate in the early stage, while Comparative Example 2 and Comparative Example 5 have the problem of low efficiency. In the embodiment of the present application, the removal rate at 1-2h mainly depends on the efficacy of catalytic degradation itself, so that the functional carrier doped with nitrogen or titanium and the mixed active material can synergistically improve the removal rate effect, thereby enabling Example 2, Example 5 and Example 6 to have a relatively excellent rate of increase in removal rate. At 3h, the continuous degradation ability of the corresponding Fe3O4 composite catalyst reflects its treatment effect in sewage treatment, and through the synergistic effect of internal doping and external functionalization, Example 2 has the most excellent and highest removal rate, and due to the single modification such as only internal doping or only external functionalization modification mode then can not achieve effective synergistic effect, thereby it is difficult to break through the bottleneck of existing removal rate, and it is difficult to achieve the purpose of significantly improving sewage treatment efficiency and reducing sewage treatment cost.

[0072] In summary, the present application provides an Fe3O4 composite catalyst and its preparation method and application. The Fe3O4 composite catalyst obtains a functional carrier by modifying the porous carrier through internal doping and external functionalization, thereby significantly improving the electron transfer rate and catalytic activity, and making the functional carrier have the ability to effectively adsorb and bind pollutants, so that after being compounded with Fe3O4, ferrous oxide and transition metal oxides, the synergistic effect with ozone is significantly improved, thereby improving the degradation efficiency of sewage. The preparation method of the Fe3O4 composite catalyst has the effects of convenient control and stable preparation, and is suitable for industrial production. The application of the Fe3O4 composite catalyst has the effect of significantly improving sewage treatment efficiency and reducing sewage treatment costs.

[0073] References to "first," "second," "third," "fourth," and the like (if any) herein are intended to distinguish similar objects and are not necessarily intended to describe a particular order or precedence. It should be understood that the numbers used in this manner are interchangeable where appropriate so that the embodiments described herein can be implemented in an order other than that described herein. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions, e.g., a process, method, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, or apparatus.

[0074] It should be noted that the descriptions of "first", "second", etc. in this application are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0075] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. An Fe3O4 composite catalyst comprising Fe3O4, ferrous oxide, a transition metal oxide, and a porous carrier, characterized in that: The transition metal oxide accounts for 1-10% of the total mass, and the porous carrier accounts for 65-85% of the total mass; the porous carrier is a functional carrier that has been subjected to internal doping modification treatment and external functionalization treatment; and the internal doping modification treatment is the use of metal or non-metal to act on the bulk phase or deep layer near the surface of the porous carrier; the external functionalization treatment is the use of polymer chains grafted to the surface layer of the porous carrier.

2. The Fe3O4 composite catalyst according to claim 1, wherein: The transition metal oxide is manganese oxide, copper oxide or cobalt oxide.

3. The Fe3O4 composite catalyst according to claim 1, wherein: The functional carrier is modified activated carbon or modified zeolite; The specific surface area S of the modified activated carbon and the modified zeolite bet ≥800m² / g.

4. A Fe3O4 composite catalyst according to claim 3, characterized in that The functional carrier is modified activated carbon, and the preparation method of the modified activated carbon comprises the following steps: Step 1: Raw material treatment: washing the activated carbon with deionized water and drying the activated carbon at 80°C until dry for later use; Step 2: Doping modification: urea and activated carbon were mixed in a mass ratio of 10:2.8-3.2, deionized water was added and stirred to obtain an activated carbon solution with a concentration of 1 g / ml, and the activated carbon solution was heated in a water bath at 58-62°C for 2-3 hours, and then pre-dried, calcined, cooled, washed, and post-dried to obtain nitrogen-doped activated carbon; Step ③ Functionalization treatment: The nitrogen-doped activated carbon was added to concentrated nitric acid and stirred evenly to obtain a doping solution with a concentration of 0.5 g / ml. The solution was heated in a water bath at 78-82°C and stirred under reflux for 4-5 hours. After the reaction was completed, the solution was cooled and washed with deionized water and dried at 78-82°C for 10-12 hours to obtain modified activated carbon that had undergone internal doping modification treatment and external functionalization treatment.

5. The Fe3O4 composite catalyst according to claim 4, characterized in that: In step ②, the pre-drying temperature is 78-82°C and the time is 8 hours; the calcination is to control the gas flow rate to be greater than or equal to 50 mL / min in a nitrogen atmosphere to heat to 500°C, control the heating rate to be 5°C / min, and keep it at 500°C for 2 hours; the post-drying temperature is 78-82°C and the time is 11-13 hours.

6. The Fe3O4 composite catalyst according to claim 3, characterized in that: The functional carrier is a modified zeolite, and the preparation method of the modified zeolite comprises the following steps: Step 1: Raw material treatment: zeolite is placed in deionized water, stirred and the supernatant is removed repeatedly to obtain clean zeolite, and then the clean zeolite is immersed in a 1 mol / L hydrochloric acid solution for 1.5-2.5 hours, controlling the solid-liquid ratio to 1:

5. Finally, the pretreated zeolite is obtained after washing with deionized water and drying. Step 2: Doping modification: dissolving titanium tetrachloride in anhydrous ethanol and stirring to obtain a 0.1 g / L titanium tetrachloride ethanol solution, then placing the pretreated zeolite into the titanium tetrachloride ethanol solution and heating it in a water bath at 58-62°C for 3.5-5 hours, controlling the mass ratio of titanium tetrachloride to pretreated zeolite to be 1:9-11, and finally filtering, washing with anhydrous ethanol, pre-drying, calcining, and cooling in sequence to obtain titanium-doped zeolite; Step ③ Functionalization treatment: The titanium-doped zeolite is put into a toluene solution of 3-aminopropyltriethoxysilane, and the amount ratio of titanium-doped zeolite, 3-aminopropyltriethoxysilane and toluene is controlled to be 25:1.95-2.05:

50. Under the protection of an inert gas atmosphere, the temperature is controlled to 78-82°C and stirred and refluxed for 6-7 hours. After the reaction is completed, it is cooled to room temperature, 3-aminopropyltriethoxysilane is removed, washed with anhydrous ethanol, and dried at 78-82°C for 8-9 hours to obtain a modified zeolite that has undergone internal doping modification treatment and external functionalization treatment.

7. The Fe3O4 composite catalyst according to claim 6, characterized in that: In step ②, the pre-drying temperature is 78-82°C for 6 hours; the calcination is carried out in an air atmosphere at a heating rate of 5°C / min to 500°C, and the temperature is kept at 500°C for 3 hours.

8. A method for preparing a Fe3O4 composite catalyst, for preparing a Fe3O4 composite catalyst according to any one of claims 1 to 7, characterized in that: The steps include: Step 1, prepare a porous support, Fe3O4, ferrous oxide, transition metal oxide, polyvinyl alcohol and anhydrous ethanol; Step 2: adding polyvinyl alcohol into anhydrous ethanol and stirring to dissolve to obtain a polyvinyl alcohol ethanol solution with a concentration of 0.02 g / ml; Step 3: Fe3O4, ferrous oxide and transition metal oxide are mixed and stirred until uniform to obtain a mixed active material; Step 4: Mix the porous support with the mixed active material and polyvinyl alcohol ethanol solution, stir and react for 6-8 hours in an oil bath at 78-82°C, and after the reaction is completed, centrifuge, wash with ethanol and vacuum dry to obtain a Fe3O4 composite catalyst.

9. The method for preparing a Fe3O4 composite catalyst according to claim 8, wherein: In step 4, the centrifugal speed is 8000 r / min and the time is 10 min; the vacuum drying temperature is 105° C. and the time is 12 h.

10. An application of a Fe3O4 composite catalyst, characterized in that: The method comprises adopting an Fe3O4 composite catalyst as described in any one of claims 1 to 6 and applying the Fe3O4 composite catalyst in combination with ozone to treat wastewater.