Efficient and Regenerable Nano Manganese Remover, and Preparation Method and Application Thereof

Abstract

The present disclosure discloses an efficient and regenerable nano manganese remover, and a method for preparing same and application thereof, belonging to the technical field of wastewater treatment and reuse. The manganese remover of the present disclosure includes Fe.sub.3O.sub.4, RGO, SiO.sub.2 and EDTA. The Fe.sub.3O.sub.4 nanoparticles are supported on the surface of the RGO, the SiO.sub.2 coats the Fe.sub.3O.sub.4, and the EDTA is grafted on the SiO.sub.2. First, Fe.sub.3O.sub.4-RGO is prepared. Then, a TEOS-ethanol solution is dropwise added, and the resulting mixture is allowed to react to obtain Fe.sub.3O.sub.4@SiO.sub.2-RGO composite particles. Finally, an EDTA-water solution is dropwise added to obtain the manganese remover. The manganese remover prepared in the present disclosure is magnetic, and the preparation process is simple and easy for industrial production. The nano manganese remover can quickly remove manganese in manganese-containing wastewater. A small amount of the manganese remover can achieve a large adsorption capacity. Further, the nano manganese remover can be separated from the manganese-containing wastewater quickly, thereby avoiding secondary pollution to the system.

Claims

1. An efficient and regenerable nano manganese remover, comprising ferrous ferric oxide (Fe.sub.3O.sub.4) nanoparticles, reduced graphene oxide (RGO), silicon dioxide (SiO.sub.2) and ethylenediaminetetraacetic acid disodium salt (EDTA), wherein the Fe.sub.3O.sub.4 nanoparticles are supported on the surface of the RGO, the SiO.sub.2 coats the Fe.sub.3O.sub.4, and the EDTA is grafted on the SiO.sub.2.

2. The efficient and regenerable nano manganese remover according to claim 1, wherein mass percentages of the Fe.sub.3O.sub.4 nanoparticles, the RGO, the SiO.sub.2 and the EDTA are respectively 5.3-16.3%, 0.37-5.7%, 7.4-76% and 17.5-86.9%.

3. A preparation method of the efficient and regenerable nano manganese remover according to claim 1, comprising the following steps: (1) preparing Fe.sub.3O.sub.4-RGO; (2) dispersing the Fe.sub.3O.sub.4-RGO prepared in step (1) in an ethanol-water solution, dropwise adding ammonia water to adjust pH to 8-13, carrying out ultrasonic dispersion for a period of time, transferring the mixture into a reactor, and dropwise adding a TEOS-ethanol solution under stirring; after the completion of the dropwise addition, continuing the reaction for a period of time; after the completion of the reaction, collecting the product with a magnet, washing the product with water, and drying the product to obtain Fe.sub.3O.sub.4@SiO.sub.2-RGO composite particles; and (3) dispersing the Fe.sub.3O.sub.4@SiO.sub.2-RGO composite particles obtained in step (2) in water, transferring the mixture into a reactor, and dropwise adding an EDTA-water solution at a certain temperature under stirring to obtain the final product of magnetic nano manganese remover Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO.

4. The preparation method according to claim 3, wherein in step (2), a volume fraction of TEOS in the TEOS-ethanol solution is 1.5-5%, and the period of time of the reaction is 8-12 hours.

5. The preparation method according to claim 3, wherein in step (3), the temperature is 50-80° C., a concentration of the EDTA-water solution is 0.050-0.175 mol/L, and the reaction is carried out for 0.5-4 hours.

6. A method of use of the efficient and regenerable nano manganese remover according to claim 1, comprising removing permanganate ions in manganese-containing wastewater by adding the efficient and regenerable nano manganese remover.

7. The method according to claim 6, wherein the manganese-containing wastewater comprises electronic waste treatment wastewater, textile wastewater, printing and dyeing wastewater, metallurgical manganese-containing wastewater after treatment with potassium permanganate, and incineration fly ash leachate.

8. The method according to claim 6, wherein the nano manganese remover is used in an amount of 0.01-100 mg/mL; and an initial concentration of permanganate in the manganese-containing wastewater is 0.1-2 mg/L.

Description

BRIEF DESCRIPTION OF FIGURES

[0031] In order to more clearly illustrate the technical solutions of the examples of the present disclosure, the accompanying drawings used in the description of the examples will be briefly described below. It is apparent that the accompanying drawings in the following description are only some examples of the present disclosure. Those skilled in the art can obtain other accompanying drawings according to these drawings without any creative work.

[0032] FIG. 1 is a TEM image of Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO prepared in Example 4 of the present disclosure;

[0033] FIG. 2 shows a standard curve of concentration vs absorbance of a permanganate ion solution; and

[0034] FIG. 3 is a graph showing the effect of dose of Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO prepared in Example 4 of the present disclosure on the removal rate of permanganate.

DETAILED DESCRIPTION

[0035] The technical solutions in the examples of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the examples of the present disclosure. It is apparent that the described examples are only a part of the examples, rather than all of the examples of the present disclosure. The following description of at least one exemplary example is merely illustrative in nature and is in no way intended to limit the present disclosure and its application or uses. All other examples obtained by those skilled in the art based on the examples in the present disclosure without creative work are within the protection scope of the present disclosure.

Example 1: Preparation of Efficient and Renewable Nano Manganese Remover

[0036] 37.5 mL of ethylene glycol and 37.5 mL of diethylene glycol were added to a 100 mL beaker. Under the action of ultrasonic stirring, 10 mg of RGO, 0.21 g of FeCl.sub.3.6H.sub.2O and 3.75 g of NaAc were added to form a homogeneous solution, and the homogeneous solution was transferred into a high pressure reactor to react at 200° C. for 8 h. After the reaction mixture was cooled to room temperature, the Fe.sub.3O.sub.4-RGO nanoparticles were collected, washed, dried and then ultrasonically dispersed in a mixture of 80 mL of ultrapure water and 20 mL of anhydrous ethanol. 25 wt % ammonia water was added to adjust the pH to 8, and the solution was transferred into a three-necked flask and stirred. 20 mL of TEOS-ethanol solution (1.5%, v/v) was dropwise added, and the mixture was stirred at room temperature for 12 h. After the completion of the reaction, magnetic separation was carried out, and the Fe.sub.3O.sub.4@SiO.sub.2-RGO composite particles were collected, washed and dried. Then, the composite particles were added to 20 mL of ultrapure water and ultrasonically dispersed. The resulting mixture was transferred to a three-necked flask. 12 mL of a 0.125 mol/L EDTA solution was dropwise added, and the system was allowed to react at 80° C. for 2 h. Magnetic separation was carried out. The obtained composite particles were washed and dried to obtain the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO magnetic nano manganese remover.

Example 2: Preparation of Efficient and Renewable Nano Manganese Remover

[0037] 37.5 mL of ethylene glycol and 37.5 mL of diethylene glycol were added to a 100 mL beaker. Under the action of ultrasonic stirring, 5 mg of RGO, 0.21 g of FeCl.sub.3.6H.sub.2O and 3.75 g of NaAc were added to form a homogeneous solution, and the homogeneous solution was transferred into a high pressure reactor to react at 200° C. for 8 h. After the reaction mixture was cooled to room temperature, the Fe.sub.3O.sub.4-RGO nanoparticles were collected, washed, dried and then ultrasonically dispersed in a mixture of 50 mL of ultrapure water and 50 mL of anhydrous ethanol. 28 wt % ammonia water was added to adjust the pH to 9, and the solution was transferred into a three-necked flask and stirred. 20 mL of TEOS-ethanol solution (5%, v/v) was dropwise added, and the mixture was stirred at room temperature for 12 h. After the completion of the reaction, magnetic separation was carried out, and the Fe.sub.3O.sub.4@SiO.sub.2-RGO composite particles were collected, washed and dried. Then, the composite particles were added to 20 mL of ultrapure water and ultrasonically dispersed. The resulting mixture was transferred to a three-necked flask. 12 mL of a 0.175 mol/L EDTA solution was dropwise added, and the system was allowed to react at 50° C. for 2 h. Magnetic separation was carried out. The obtained composite particles were washed and dried to obtain the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO magnetic nano manganese remover.

Example 3: Preparation of Efficient and Renewable Nano Manganese Remover

[0038] 37.5 mL of ethylene glycol and 37.5 mL of diethylene glycol were added to a 100 mL beaker. Under the action of ultrasonic stirring, 10 mg of RGO, 0.21 g of FeCl.sub.3.6H.sub.2O and 3.75 g of NaAc were added to form a homogeneous solution, and the homogeneous solution was transferred into a high pressure reactor to react at 180° C. for 10 h. After the reaction mixture was cooled to room temperature, the Fe.sub.3O.sub.4-RGO nanoparticles were collected, washed, dried and then ultrasonically dispersed in a mixture of 60 mL of ultrapure water and 40 mL of anhydrous ethanol. 25 wt % ammonia water was added to adjust the pH to 13, and the solution was transferred into a three-necked flask and stirred. 20 mL of TEOS-ethanol solution (5%, v/v) was dropwise added, and the mixture was stirred at room temperature for 8 h. After the completion of the reaction, magnetic separation was carried out, and the Fe.sub.3O.sub.4@SiO.sub.2-RGO composite particles were collected, washed and dried. Then, the composite particles were added to 20 mL of ultrapure water and ultrasonically dispersed. The resulting mixture was transferred to a three-necked flask. 12 mL of a 0.050 mol/L EDTA solution was dropwise added, and the system was allowed to react at 60° C. for 1 h. Magnetic separation was carried out. The obtained composite particles were washed and dried to obtain the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO magnetic nano manganese remover.

Example 4: Preparation of Efficient and Renewable Nano Manganese Remover

[0039] 37.5 mL of ethylene glycol and 37.5 mL of diethylene glycol were added to a 100 mL beaker. Under the action of ultrasonic stirring, 10 mg of RGO, 0.21 g of FeCl.sub.3.6H.sub.2O and 3.75 g of NaAc were added to form a homogeneous solution, and the homogeneous solution was transferred into a high pressure reactor to react at 200° C. for 8 h. After the reaction mixture was cooled to room temperature, the Fe.sub.3O.sub.4-RGO nanoparticles were collected, washed, dried and then ultrasonically dispersed in a mixture of 80 mL of ultrapure water and 20 mL of anhydrous ethanol. 28 wt % ammonia water was added to adjust the pH to 13, and the solution was transferred into a three-necked flask and stirred. 20 mL of TEOS-ethanol solution (1.5%, v/v) was dropwise added, and the mixture was stirred at room temperature for 12 h. After the completion of the reaction, magnetic separation was carried out, and the Fe.sub.3O.sub.4@SiO.sub.2-RGO composite particles were collected, washed and dried. Then, the composite particles were added to 20 mL of ultrapure water and ultrasonically dispersed. The resulting mixture was transferred to a three-necked flask. 12 mL of a 0.125 mol/L EDTA solution was dropwise added, and the system was allowed to react at 70° C. for 2 h. Magnetic separation was carried out. The obtained composite particles were washed and dried to obtain the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO magnetic nano manganese remover.

Example 5: Preparation of Efficient and Renewable Nano Manganese Remover

[0040] 37.5 mL of ethylene glycol and 18.5 mL of diethylene glycol were added to a 100 mL beaker. Under the action of ultrasonic stirring, 6 mg of RGO, 0.15 g of FeCl.sub.3.6H.sub.2O and 2.55 g of NaAc were added to form a homogeneous solution, and the homogeneous solution was transferred into a high pressure reactor to react at 200° C. for 8 h. After the reaction mixture was cooled to room temperature, the Fe.sub.3O.sub.4-RGO nanoparticles were collected, washed, dried and then ultrasonically dispersed in a mixture of 80 mL of ultrapure water and 20 mL of anhydrous ethanol. 10 wt % ammonia water was added to adjust the pH to 8, and the solution was transferred into a three-necked flask and stirred. 20 mL of TEOS-ethanol solution (2%, v/v) was dropwise added, and the mixture was stirred at room temperature for 12 h. After the completion of the reaction, magnetic separation was carried out, and the Fe.sub.3O.sub.4@SiO.sub.2-RGO composite particles were collected, washed and dried. Then, the composite particles were added to 20 mL of ultrapure water and ultrasonically dispersed. The resulting mixture was transferred to a three-necked flask. 12 mL of a 0.050 mol/L EDTA solution was dropwise added, and the system was allowed to react at 80° C. for 1 h. Magnetic separation was carried out. The obtained composite particles were washed and dried to obtain the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO magnetic nano manganese remover.

Example 6: Preparation of Efficient and Renewable Nano Manganese Remover

[0041] 25 mL of ethylene glycol and 37.5 mL of diethylene glycol were added to a 100 mL beaker. Under the action of ultrasonic stirring, 6 mg of RGO, 0.15 g of FeCl.sub.3.6H.sub.2O and 2.55 g of NaAc were added to form a homogeneous solution, and the homogeneous solution was transferred into a high pressure reactor to react at 220° C. for 6 h. After the reaction mixture was cooled to room temperature, the Fe.sub.3O.sub.4-RGO nanoparticles were collected, washed, dried and then ultrasonically dispersed in a mixture of 80 mL of ultrapure water and 20 mL of anhydrous ethanol. 25 wt % ammonia water was added to adjust the pH to 10, and the solution was transferred into a three-necked flask and stirred. 20 mL of TEOS-ethanol solution (1.5%, v/v) was dropwise added, and the mixture was stirred at room temperature for 10 h. After the completion of the reaction, magnetic separation was carried out, and the Fe.sub.3O.sub.4@SiO.sub.2-RGO composite particles were collected, washed and dried. Then, the composite particles were added to 20 mL of ultrapure water and ultrasonically dispersed. The resulting mixture was transferred to a three-necked flask. 12 mL of a 0.125 mol/L EDTA solution was dropwise added, and the system was allowed to react at 60° C. for 4 h. Magnetic separation was carried out. The obtained composite particles were washed and dried to obtain the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO magnetic nano manganese remover.

Test Example 1

[0042] The magnetic nano manganese remover (Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO) prepared in Example 4 was characterized by transmission electron microscopy (TEM). As shown in FIG. 1, the large area of wrinkled substance is RGO. As can be clearly observed, the black nanoparticles are Fe.sub.3O.sub.4 nanoparticles, and the light colored part uniformly surrounding the black nanoparticle is SiO.sub.2. The Fe.sub.3O.sub.4@SiO.sub.2 particles have a uniform size of about 100 nm and are uniformly supported on the surface of the RGO without obvious agglomeration. That is, the Fe.sub.3O.sub.4 nanoparticles are supported on the surface of the RGO, the SiO.sub.2 coats the Fe.sub.3O.sub.4, and the EDTA is grafted on the SiO.sub.2.

Application Example 1 Removal of Permanganate Ions

[0043] The Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO prepared in Example 4 was subjected to a manganese adsorption test, including the following steps:

[0044] (1) Drawing of standard curve: Potassium permanganate solutions with concentrations of 1.6 mg/L, 0.8 mg/L, 0.4 mg/L, 0.2 mg/L and 0.1 mg/L were prepared. The absorbance (A) of the corresponding solution at a wavelength λ=525 nm was measured by an ultraviolet spectrophotometer. The standard curve was drawn with the concentration of permanganate ions as the abscissa and the absorbance as the ordinate. Line fitting was carried out to obtain the equation of the standard curve of permanganate ions: y=0.0709x−0.0022, R.sup.2=0.9996. FIG. 2 shows a good linear relationship between the concentration of permanganate ions and the absorbance.

[0045] (2) Simulation of manganese-containing wastewater: A permanganate ion solution with an initial concentration of 2 mg/L was prepared to simulate the manganese-containing wastewater. Then, 6 aliquots of 20 mL solution were pipetted from the permanganate ion solution into glass bottles as manganese-containing wastewater. 0.2 mg, 0.3 mg, 0.4 mg, 0.5 mg, 1 mg and 2 mg of the magnetic nano manganese remover (Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO) prepared in Example 4 were respectively added to the 6 aliquots of solution. After ultrasonic dispersion, the resulting mixture was shaken in an air bath thermostatic shaker at 25° C. at a speed of 160 r/min for 90 minutes. After the completion of the shaking, the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO was enriched to the bottom of the glass bottle through a magnetic decantation process. The absorbances of the 6 aliquots of permanganate ion solution obtained after manganese removal with the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO at the wavelength λ=525 nm were measured by the ultraviolet spectrophotometer. With reference to FIG. 2, based on the absorbance, the concentration of the corresponding permanganate ion solution obtained after manganese removal with the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO (the concentration of remaining permanganate ions) was calculated. Then, according to the formula:

[00001]$R\left(\%\right)=\frac{C_0-C_e}{C_0}\times 100\%,$

the removal rate of permanganate ions by the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO was calculated. In the formula, Co (mg/L) and C.sub.e (mg/L) are respectively the initial concentration of the permanganate ion solution and the concentration of remaining permanganate ions after manganese removal with the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO. A graph was drawn based on the concentration of remaining permanganate ions and the removal rate, as shown in FIG. 3.

[0046] As can be seen from FIG. 3, as the dose of the magnetic Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO increases, the concentration of permanganate ions in the solution decreases sharply, and the removal rate of permanganate ions increases accordingly. When the dose is 0.5 mg, the removal rate of permanganate ions is as high as 95.47%. Then, as the dose continues increasing, the removal rate of permanganate ions still increases, but with an extremely small slope. After the dose of 1 mg of Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO at which the removal rate of permanganate ions is 97.76%, the removal rate increases with an extremely small slope. As a result, when the nano manganese remover prepared by the present disclosure is used to remove manganese from water, a small dose can achieve a good manganese removal effect. Therefore, the nano manganese remover prepared by the present disclosure is expected to become an efficient manganese remover for wastewater.

[0047] The nano manganese removers Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO prepared in other examples were tested according to the above method. When the dose was in the range of 0.5-1 mg, the removal rate of permanganate ions was also as high as 90% or above.

[0048] The manganese remover of the present disclosure has the advantages of high removal efficiency for low-concentration permanganate ions, small dosage and no secondary pollution to water. Besides, the manganese remover of the present disclosure is recyclable and reusable, and still has a good removal rate after many adsorption-desorption cycles.

[0049] Regeneration test: The Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO of Example 4 with potassium permanganate adsorbed thereon was enriched using a magnet, and then treated with a dilute HCl solution to make it desorb permanganate. The Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO was enriched with an external magnetic field and then washed for reuse. The regenerated Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO continued to be used in the above manganese removal process, with a dose of 0.5 mg for 5 cycles. The manganese removal effect is shown in Table 1. As can be seen, the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO is stable, recyclable and reusable, and still has a good adsorption effect after many adsorption-desorption cycles.

TABLE-US-00001 TABLE 1 Removal rate of permanganate by Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO after 5 cycles Number of cycles 0 1 2 3 4 5 Removal 95.47 93.86 90.98 89.33 86.71 85.23 rate/%

Comparative Example 1

[0050] 50 mL of ethylene glycol was added to a 100 mL beaker. Under the action of ultrasonic stirring, 0.21 g of FeCl.sub.3.6H.sub.2O and 3.75 g of NaAc were added to form a homogeneous solution, and the homogeneous solution was transferred into a high pressure reactor to react at 200° C. for 8 h. After the reaction mixture was cooled to room temperature, the Fe.sub.3O.sub.4 nanoparticles were collected, washed, dried and then ultrasonically dispersed in a mixture of 80 mL of ultrapure water and 20 mL of anhydrous ethanol. 28 wt % ammonia water was added to adjust the pH to 13, and the solution was transferred into a three-necked flask and stirred. 20 mL of TEOS-ethanol solution (1.5%, v/v) was dropwise added, and the mixture was stirred at room temperature for 12 h. After the completion of the reaction, magnetic separation was carried out, and the Fe.sub.3O.sub.4@SiO.sub.2 composite particles were collected, washed and dried. Then, the composite particles were added to 80 mL of ultrapure water, and 10 mg of RGO was added under ultrasonic dispersion. After the RGO was dispersed uniformly, the resulting mixture was transferred into a high pressure reactor and allowed to react at 120° C. for 6 h. After the completion of the reaction, the reaction mixture was cooled to room temperature. Magnetic separation was carried out. The obtained composite particles were washed and dispersed in 20 mL of ultrapure water. 12 mL of 0.125 mol/L EDTA solution was dropwise added, and the system was allowed to react at 70° C. for 2 h. Magnetic separation was carried out. The obtained composite particles were washed and dried to obtain the Fe.sub.3O.sub.4@SiO.sub.2@EDTA-RGO magnetic nano composite material.

[0051] The adsorption capacity for permanganate was tested according to the method in Application Example 1. It was found that when the dose was 0.5 mg, the removal rate of permanganate was 70.34%.

Comparative Example 2

[0052] 37.5 mL of ethylene glycol and 37.5 mL of diethylene glycol were added to a 100 mL beaker. Under the action of ultrasonic stirring, 10 mg of RGO, 0.21 g of FeCl.sub.3.6H.sub.2O and 3.75 g of NaAc were added to form a homogeneous solution, and the homogeneous solution was transferred into a high pressure reactor to react at 200° C. for 8 h. After the reaction mixture was cooled to room temperature, the Fe.sub.3O.sub.4-RGO nanoparticles were collected, washed, dried and then ultrasonically dispersed in a mixture of 80 mL of ultrapure water and 20 mL of anhydrous ethanol. 28 wt % ammonia water was added to adjust the pH to 13, and the solution was transferred into a three-necked flask and stirred. 0.3 mL of TEOS was added, and the mixture was stirred at room temperature for 12 h. After the completion of the reaction, magnetic separation was carried out, and the Fe.sub.3O.sub.4@SiO.sub.2-RGO composite particles were collected, washed and dried. Then, the composite particles were added to 20 mL of ultrapure water and ultrasonically dispersed. The resulting mixture was transferred to a three-necked flask. 12 mL of a 0.125 mol/L EDTA solution was dropwise added, and the system was allowed to react at 70° C. for 2 h. Magnetic separation was carried out. The obtained composite particles were washed and dried to obtain the composite product. The composite product was characterized by transmission electron microscopy (TEM). It was found that SiO.sub.2 did not effectively and uniformly coat Fe.sub.3O.sub.4 nanoparticles, but formed SiO.sub.2 spheroidal monomers in a large proportion, and the magnetic nano composite material could not be formed effectively.

Comparative Example 3

[0053] Disodium EDTA alone cannot adsorb permanganate due to its extremely high stability: there is no reducing group. EDTA and permanganate ions are both negative ions and repel each other, but when EDTA is supported on Fe.sub.3O.sub.4@SiO.sub.2-RGO, trapped charges at the SiO.sub.2 interface are positive charges, which makes the adsorption of permanganate possible through charge transfer.

Comparative Example 4

[0054] 50 mL of ethylene glycol was added to a 100 mL beaker. Under the action of ultrasonic stirring, 0.21 g of FeCl.sub.3.6H.sub.2O and 3.75 g of NaAc were added to form a homogeneous solution, and the homogeneous solution was transferred into a high pressure reactor to react at 200° C. for 8 h. After the reaction mixture was cooled to room temperature, the Fe.sub.3O.sub.4 nanoparticles were collected, washed, dried and then ultrasonically dispersed in a mixture of 80 mL of ultrapure water and 20 mL of anhydrous ethanol. 28 wt % ammonia water was added to adjust the pH to 13, and the solution was transferred into a three-necked flask and stirred. 20 mL of a TEOS-ethanol solution (1.5%, v/v) was dropwise added, and the mixture was stirred at room temperature for 12 h. After the completion of the reaction, magnetic separation was carried out, and the Fe.sub.3O.sub.4@SiO.sub.2 composite particles were collected and washed. Then, the composite particles were ultrasonically dispersed in 20 mL of ultrapure water. 12 mL of a 0.125 mol/L EDTA solution was dropwise added, and the system was allowed to react at 70° C. for 2 h. Magnetic separation was carried out. The obtained composite particles were washed and dried to obtain the Fe.sub.3O.sub.4@SiO.sub.2@EDTA magnetic nano composite material.

[0055] The adsorption capacity for permanganate was tested according to the method in Application Example 1. It was found that when the dose was 0.5 mg, the removal rate of permanganate was 57.31%.

[0056] Although the present disclosure has been disclosed as above by way of the preferred examples, they are not intended to limit the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure should be as defined in the claims.