MESOPOROUS MANGANESE FERRITE FENTON-LIKE CATALYST, PREPARATION METHOD THEREFOR, AND APPLICATION THEREOF

Abstract

The present invention discloses a mesoporous manganese ferrite Fenton-like catalyst and preparation method and application thereof and pertains to the field of preparation of Fenton-like catalysts. The present invention uses KIT-6 as a hard template agent to synthesize mesoporous manganese ferrite catalyst. The prepared mesoporous manganese ferrite and hydrogen peroxide constitute a Fenton-like system oxidation wastewater treatment system to carry out efficient removal and mineralization of organic pollutants in wastewater. The preparation method of the present invention is simple and efficient. The prepared Fenton-like catalyst has a mesoporous structure and a relatively large specific surface area. It can provide more adsorption sites and catalytic site and efficiently degrade pollutants in a wide pH range (acidic, neutral and even alkaline) and solves the problem that conventional Fenton reaction occurs only under an acidic condition and a large amount of iron sludge is generated during reaction, causing secondary pollution. Further, the catalyst can be used cyclically and easily separated from the water solution and recovered after use.

Claims

1. A method for preparing mesoporous manganese ferrite Fenton-like catalytic material, comprising the following steps: (1) dissolve molecular sieve KIT-6, and iron salt and manganese salt at a molar ratio of 0.5-1:2 in an alcoholic solution, reflow under magnetic stirring for 1224 h, cool the solution, filter it and dry the filtrate; (2) put the foregoing product obtained from filtration in a tube furnace, hold temperature at 150-300 C. for 3-5 h, and then hold temperature at 450-600 C. for 3-5 h; (3) stir the product obtained after calcinations at step (2) in a NaOH solution for 12-24 h to remove KIT-6 template agent, stir the mixed solution, centrifuge it, wash it with water till the supernate is neutral, and freeze-dry the precipitate.

2. The method for preparing mesoporous manganese ferrite Fenton-like catalytic material according to claim 1, wherein the alcoholic solution at step (1) is methanol, ethanol or ethylene glycol, and the heating temperature under magnetic stirring is 5080 C.

3. The method for preparing mesoporous manganese ferrite Fenton-like catalytic material according to claim 1, wherein the heating rate in the tube furnace at step (2) is 510 C./min.

4. The method for preparing mesoporous manganese ferrite Fenton-like catalytic material according to claim 1, wherein the molar concentration of NaOH at step (3) is 13 mol/L.

5. The method for preparing mesoporous manganese ferrite Fenton-like catalytic material according to claim 1, wherein the iron salt at step (1) is Fe(NO.sub.3).sub.3.9H.sub.2O or FeCl.sub.3.6H.sub.2O, and the manganese salt is Mn(NO.sub.3).sub.2.4H.sub.2O or MnCl.sub.2.4H.sub.2O.

6. A mesoporous manganese ferrite Fenton-like catalytic material prepared by the method as in claim 1, wherein it is constituted by metal oxides of MnFe.sub.2O.sub.4 and the surface morphology is mesoporous structure.

7-8. (canceled)

9. A mesoporous manganese ferrite Fenton-like catalytic material prepared by the method as in claim 3, wherein it is constituted by metal oxides of MnFe.sub.2O.sub.4 and the surface morphology is mesoporous structure.

10. The mesoporous manganese ferrite Fenton-like catalytic material according to claim 6, wherein the specific surface area is 109.99 m.sup.2/g, the mean pore diameter is 3.564 nm and the mean pore volume is 0.209 cm.sup.3/g.

11. The mesoporous manganese ferrite Fenton-like catalytic material according to claim 9, wherein the specific surface area is 109.99 m.sup.2/g, the mean pore diameter is 3.564 nm and the mean pore volume is 0.209 cm.sup.3/g.

12. A Fenton-like system constituted by the mesoporous manganese ferrite Fenton-like catalytic material as in claim 6 and hydrogen peroxide and used to treat oxidation wastewater.

13. A Fenton-like system constituted by the mesoporous manganese ferrite Fenton-like catalytic material as in claim 9 and hydrogen peroxide and used to treat oxidation wastewater.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a schematic diagram for catalytic degradation of methylene blue by manganese ferrite MnFe.sub.2O.sub.4 of mesoporous Fenton-like catalyst;

[0032] FIG. 2 is a N.sub.2 adsorption and desorption curve and a pore diameter distribution diagram of manganese ferrite MnFe.sub.2O.sub.4 of mesoporous Fenton-like catalyst synthesized in Embodiment 3;

[0033] FIG. 3 is an SEM image of KIT-6, magnified by 20,000 times;

[0034] FIG. 4 is an SEM image of mesoporous manganese ferrite synthesized in Embodiment 1, magnified by 20,000 times;

[0035] FIG. 5 is an SEM image of mesoporous manganese ferrite synthesized in Embodiment 2, magnified by 60,000 times;

[0036] FIG. 6 is an SEM image of mesoporous manganese ferrite synthesized in Embodiment 3, magnified by 60,000 times;

[0037] FIG. 7 is an electron spectrum of mesoporous manganese ferrite synthesized in Embodiment 3;

[0038] FIG. 8 is Mn2p spectrum of the electron spectrum of mesoporous manganese ferrite synthesized in Embodiment 3;

[0039] FIG. 9 is Fe2p spectrum of the electron spectrum of mesoporous manganese ferrite synthesized in Embodiment 3.

[0040] FIG. 10 is XRD patterns of mesoporous manganese ferrite MnFe.sub.2O.sub.4 synthesized in Embodiments 1, 2 & 3.

[0041] FIG. 11 is an effect diagram of catalytic degradation of methylene blue by manganese ferrite MnFe.sub.2O.sub.4 in Embodiments 1, 2, 3, 4, 5, 6 & 7.

DETAILED DESCRIPTION

Embodiment 1

[0042] A method for preparing mesoporous manganese ferrite Fenton-like catalyst, comprising the following steps:

[0043] (1) Dissolve molecular sieve KIT-6, FeCl.sub.3.6H.sub.2O and MnCl.sub.2.4H.sub.2O in an alcoholic solution, reflow under magnetic stirring for 12 h, cool the solution, filter it and dry the filtrate. Here, the molar ratio between iron salt and manganese salt is 0.5:2, the alcoholic solution is methanol, and the temperature of magnetic stirring is 70 C. The SEM image of molecular sieve KIT-6 is as shown in FIG. 3.

[0044] (2) Put the foregoing product in a tube furnace in an air atmosphere, hold temperature at 200 C. for 3 h, and then hold temperature at 550 C. for 3 h. Here, the heating rate of the tube furnace is 5 C./min.

[0045] (3) Stir the post-calcinations product in a NaOH solution for 24 h to remove KIT-6 template agent, stir the mixed solution, centrifuge it, wash it with water three times till the supernate is neutral, and freeze-dry the precipitate. Here, the molar concentration of NaOH is 2 mol/L. FIG. 4 is an SEM image of mesoporous manganese ferrite synthesized in this embodiment, and FIG. 10 is XRD patterns of mesoporous manganese ferrite MnFe.sub.2O.sub.4 synthesized in Embodiment 1.

[0046] Experiment of Fenton-Like Catalytic Degradation of Methylene Blue:

[0047] Prepare 200 mL of 20 mg/L methylene blue solution in a conical flask, adjust initial pH value to 4, and add 0.1 g of the prepared mesoporous manganese ferrite. Put the solution in a 25 C. 150 rpm shaking table for adsorption equilibrium for 30 min, then take it out, add 45 mmol/L hydrogen peroxide to form a Fenton-like system for the treatment of oxidation wastewater, take a sample at every quantitative time and determine the concentration of methylene blue. FIG. 1 is an effect diagram for catalytic degradation of methylene blue by manganese ferrite MnFe.sub.2O.sub.4 of mesoporous Fenton-like catalyst in Embodiment 1: Mn and Fe on the surface of hydrogen peroxide and manganese ferrite take redox reaction to generate .OH, free radical degrades methylene blue into organic acids and other intermediate products in the diffusion layer on or near the surface of iron oxides, and eventually degrades it into carbon dioxide and water. The treatment result is shown in FIG. 11. Under an acidic condition, the degradation rate of methylene blue within 60 min by the material synthesized in Embodiment 1 is about 55%.

Embodiment 2

[0048] (1) Dissolve molecular sieve KIT-6, Fe(NO.sub.3).sub.3.9H.sub.2O and Mn(NO.sub.3).sub.2.4H.sub.2O in an alcoholic solution, reflow under magnetic stirring for 16 h, cool the solution, filter it and dry the filtrate. Here, the molar ratio between iron salt and manganese salt is 0.75:2, the alcoholic solution is methanol, and the temperature of magnetic stirring is 80 C.

[0049] (2) Put the foregoing product in a tube furnace in an air atmosphere, hold temperature at 300 C. for 4 h, and then hold temperature at 600 C. for 4 h. Here, the heating rate of the tube furnace is 10 C./min.

[0050] (3) Stir the post-calcinations product in a NaOH solution for 12 h to remove KIT-6 template agent, stir the mixed solution, centrifuge it, wash it with water three times till the supernate is neutral, and freeze-dry the precipitate. Here, the molar concentration of NaOH is 3 mol/L. FIG. 5 is an SEM image of mesoporous manganese ferrite synthesized in this embodiment, and FIG. 10 is XRD patterns of mesoporous manganese ferrite MnFe.sub.2O.sub.4 synthesized in Embodiment 2.

[0051] (4) Experiment of Fenton-like catalytic degradation of methylene blue: Prepare 200 mL of 20 mg/L methylene blue solution in a conical flask, adjust initial pH value to 4, and add 0.1 g of the prepared mesoporous manganese ferrite. Put the solution in a 25 C. 150 rpm shaking table for adsorption equilibrium for 30 min, then take it out, add 45 mmol/L hydrogen peroxide, take a sample at every quantitative time and determine the concentration of methylene blue. The result is shown in FIG. 11. Under acidic condition, the degradation rate of methylene blue by the material synthesized in Embodiment 2 is about 80% within 60 min.

Embodiment 3

[0052] (1) Dissolve molecular sieve KIT, Fe(NO.sub.3).sub.3.9H.sub.2O and Mn(NO.sub.3).sub.2.4H.sub.2O in an alcoholic solution, reflow under magnetic stirring for 24 h, cool the solution, filter it and dry the filtrate. Here, the molar ratio between iron salt and manganese salt is 1:2, the alcoholic solution is ethanol, and the temperature of magnetic stirring is 70 C.

[0053] (2) Put the foregoing product in a tube furnace in an air atmosphere, hold temperature at 200 C. for 5 h, and then hold temperature at 550 C. for 5 h. Here, the heating rate of the tube furnace is 5 C./min.

[0054] (3) Stir the post-calcinations product in a NaOH solution for 24 h to remove KIT-6 template agent, stir the mixed solution, centrifuge it, wash it with water three times till the supernate is neutral, and freeze-dry the precipitate. Here, the molar concentration of NaOH is 2 mol/L. FIG. 6 is an SEM image of mesoporous manganese ferrite synthesized in this embodiment. FIG. 7 is XPS spectrum of synthesized mesoporous manganese ferrite MnFe.sub.2O.sub.4. FIG. 10 is XRD patterns of mesoporous manganese ferrite MnFe.sub.2O.sub.4 of mesoporous Fenton-like catalyst synthesized in Embodiment 3, and 2 angles of 29.65, 34.92, 42.43, 52.61 and 61.56 correspond to crystal faces (220), (311), (400), (422), (511) and (440) of manganese ferrite. FIG. 2 is a N.sub.2 adsorption and desorption curve and a pore diameter distribution diagram of the product synthesized in this embodiment, and in BJH calculation model, the specific surface area of mesoporous manganese ferrite is 109.99 m.sup.2/g and the mean pore diameter is 3.564 nm. FIG. 8 and FIG. 9 are electron binding energy spectra of Mn 2p and Fe 2p of synthesized mesoporous manganese ferrite. The two peaks at 640.5 eV and 652.5 eV in Mn 2p spectrum correspond to Mn 2p.sub.3/2 and Mn 2p.sub.1/2. The two peaks at 724.6 eV and 710.8 eV in Fe 2p spectrum correspond to Fe 2p.sub.3/2 and Fe 2p.sub.1/2.

TABLE-US-00001 TABLE 1 BET result of MnFe.sub.2O.sub.4 synthesized in Embodiment 3: Specific surface area 109.99 m.sup.2/g Mean pore volume 0.209 cm.sup.3/g Mean pore diameter 3.564 nm

[0055] (4) Experiment of Fenton-like catalytic degradation of methylene blue: Prepare 200 mL of 20 mg/L methylene blue solution in a conical flask, adjust initial pH value to 4, and add 0.1 g of mesoporous manganese ferrite. Put the solution in a 25 C. 150 rpm shaking table for adsorption equilibrium for 30 min, then take it out, add 45 mmol/L hydrogen peroxide, take a sample at every quantitative time and determine the concentration of methylene blue. The result is shown in FIG. 11. The diagram shows that under an alkaline condition, the degradation rate of methylene blue by manganese ferritemanganese ferrite within 60 min can exceed 90%.

Embodiment 4

[0056] (1) Dissolve molecular sieve KIT-6, Fe(NO.sub.3).sub.3.9H.sub.2O and Mn(NO.sub.3).sub.2.4H.sub.2O in an alcoholic solution, reflow under magnetic stirring for 24 h, cool the solution, filter it and dry the filtrate. Here, the molar ratio between iron salt and manganese salt is 1:2, the alcoholic solution is ethanol, and the temperature of magnetic stirring is 50 C.

[0057] (2) Put the foregoing product in a tube furnace in an air atmosphere, hold temperature at 150 C. for 5 h, and then hold temperature at 450 C. for 5 h. Here, the heating rate of the tube furnace is 7 C./min.

[0058] (3) Stir the post-calcinations product in a NaOH solution for 16 h to remove KIT-6 template agent, stir the mixed solution, centrifuge it, wash it with water three times till the supernate is neutral, and freeze-dry the precipitate. Here, the molar concentration of NaOH is 1 mol/L.

[0059] (4) Experiment of Fenton-like catalytic degradation of methylene blue: Prepare 200 mL of 20 mg/L methylene blue solution in a conical flask, adjust initial pH value to 4, and add 0.1 g of mesoporous manganese ferrite. Put the solution in a 25 C. 150 rpm shaking table for adsorption equilibrium for 30 min, then take it out, add 45 mmol/L hydrogen peroxide, take a sample at every quantitative time and determine the concentration of methylene blue. The result is shown in FIG. 11. The degradation rate of methylene blue within 60 min by the manganese ferritemanganese ferrite synthesized under the conditions of Embodiment 4 can exceed 90%.

Embodiment 5

[0060] (1) Dissolve molecular sieve KIT-6, Fe(NO.sub.3).sub.3.9H.sub.2O and Mn(NO.sub.3).sub.2.4H.sub.2O in an alcoholic solution, reflow under magnetic stirring for 24 h, cool the solution, filter it and dry the filtrate. Here, the molar ratio between iron salt and manganese salt is 1:2, the alcoholic solution is ethylene glycol, and the temperature of magnetic stirring is 60 C.

[0061] (2) Put the foregoing product in a tube furnace in an air atmosphere, hold temperature at 200 C. for 5 h, and then hold temperature at 550 C. for 5 h. Here, the heating rate of the tube furnace is 5 C./min.

[0062] (3) Stir the post-calcinations product in a NaOH solution for 24 h to remove KIT-6 template agent, stir the mixed solution, centrifuge it, wash it with water three times till the supernate is neutral, and freeze-dry the precipitate. Here, the molar concentration of NaOH is 2 mol/L.

[0063] (4) Experiment of Fenton-like catalytic degradation of methylene blue: Prepare 200 mL of 20 mg/L methylene blue solution in a conical flask, adjust initial pH value to 6, and add 0.1 g of mesoporous manganese ferrite. Put the solution in a 25 C. 150 rpm shaking table for adsorption equilibrium for 30 min, then take it out, add 45 mmol/L hydrogen peroxide, take a sample at every quantitative time and determine the concentration of methylene blue. The result is shown in FIG. 11. The diagram shows that under an almost neutral condition, the degradation rate of methylene blue by manganese ferritemanganese ferrite within 60 min can exceed 90%.

Embodiment 6

[0064] (1) Dissolve molecular sieve KIT-6, Fe(NO.sub.3).sub.3.9H.sub.2O and Mn(NO.sub.3).sub.2.4H.sub.2O in an alcoholic solution, reflow under magnetic stirring for 24 h, cool the solution, filter it and dry the filtrate. Here, the molar ratio between iron salt and manganese salt is 1:2, the alcoholic solution is ethanol, and the temperature of magnetic stirring is 60 C.

[0065] (2) Put the foregoing product in a tube furnace in an air atmosphere, hold temperature at 200 C. for 5 h, and then hold temperature at 550 C. for 5 h. Here, the heating rate of the tube furnace is 5 C./min.

[0066] (3) Stir the post-calcinations product in a NaOH solution for 24 h to remove KIT-6 template agent, stir the mixed solution, centrifuge it, wash it with water three times till the supernate is neutral, and freeze-dry the precipitate. Here, the molar concentration of NaOH is 2 mol/L.

[0067] (4) Experiment of Fenton-like catalytic degradation of methylene blue: Prepare 200 mL of 20 mg/L methylene blue solution in a conical flask, adjust initial pH value to 8, and add 0.1 g of mesoporous manganese ferrite. Put the solution in a 25 C. 150 rpm shaking table for adsorption equilibrium for 30 min, then take it out, add 45 mmol/L hydrogen peroxide, take a sample at every quantitative time and determine the concentration of methylene blue. The result is shown in FIG. 11.

Embodiment 7

[0068] (1) Dissolve molecular sieve KIT-6, Fe(NO.sub.3).sub.3.9H.sub.2O and Mn(NO.sub.3).sub.2.4H.sub.2O in an alcoholic solution, reflow under magnetic stirring for 24 h, cool the solution, filter it and dry the filtrate. Here, the molar ratio between iron salt and manganese salt is 1:2, the alcoholic solution is ethanol, and the temperature of magnetic stirring is 60 C.

[0069] (2) Put the foregoing product in a tube furnace in an air atmosphere, hold temperature at 200 C. for 5 h, and then hold temperature at 550 C. for 5 h. Here, the heating rate of the tube furnace is 5 C./min.

[0070] (3) Stir the post-calcinations product in a NaOH solution for 24 h to remove KIT-6 template agent, stir the mixed solution, centrifuge it, wash it with water three times till the supernate is neutral, and freeze-dry the precipitate. Here, the molar concentration of NaOH is 2 mol/L.

[0071] (4) Experiment of Fenton-like catalytic degradation of methylene blue: Prepare 200 mL of 20 mg/L methylene blue solution in a conical flask, adjust initial pH value to 10, and add 0.1 g of mesoporous manganese ferrite. Put the solution in a 25 C. 150 rpm shaking table for adsorption equilibrium for 30 min, then take it out, add 45 mmol/L hydrogen peroxide, take a sample at every quantitative time and determine the concentration of methylene blue. The result is shown in FIG. 11. The diagram shows that under an alkaline condition, the degradation rate of methylene blue by manganese ferritemanganese ferrite within 60 min can exceed 90%.