Application of graphene oxide / metal organic framework modified magnetic nanoparticles as perchlorate extraction material

Abstract

The invention belongs to the technical field of perchlorate treatment, and discloses application of graphene oxide / metal organic framework modified magnetic nanoparticles as a perchlorate extraction material, and an application method comprises the following steps: adding the graphene oxide / metal organic framework modified magnetic nanoparticles Fe3O4 (at) GO (at) MIL-53 (Al)-NH2 into perchlorate wastewater; according to the method, perchlorate is rapidly extracted under the action of external mechanical stirring, and then used Fe3O4 (at) GO (at) MIL-53 (Al)-NH2 is separated and recycled by virtue of a magnetic field, so that purified water is obtained. According to the Fe3O4 (at) GO (at) MIL-53 (Al)-NH2, magnetic ferroferric oxide serves as an inner core, a composite functional group composed of graphene oxide and a metal organic framework material is arranged on the surface, and the Fe3O4 (at) GO (at) MIL-53 (Al)-NH2 is used for extracting perchlorate and has the advantages of being high in extraction speed and extraction efficiency, easy to regenerate and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of perchlorate treatment, and in particular relates to the application of magnetic nanoparticles modified by graphene oxide / metal organic framework as perchlorate extraction materials. Background Art

[0002] Perchlorate is a toxic inorganic chemical substance. In recent years, the safety of perchlorate has received more and more attention. Therefore, it is of great significance to monitor and remove perchlorate in environmental water samples. The removal of perchlorate can be divided into two categories: physical removal and chemical removal. Among them, the commonly used chemical reactions include chemical degradation, electrochemical degradation and catalytic degradation, but they are usually complicated to operate, the removal efficiency is not high, and other chemical reagents such as catalysts need to be added during the reaction process, which easily leads to secondary pollution problems.

[0003] Compared with chemical removal, physical removal has the advantages of simple operation process and high removal efficiency. Physical removal mainly achieves the removal effect by realizing the protonation transfer of perchlorate in water through adsorption and other forces. The main methods include adsorption, ion exchange and membrane filtration. Activated carbon is the earliest material used for perchlorate removal. On this basis, carbon nanotubes, chitosan and other materials are also used to remove perchlorate in water samples. These materials have the advantages of low cost, but these materials only use physical adsorption such as the pore structure of the adsorption material, and the adsorption kinetics are slow, resulting in a long treatment time and reduced treatment efficiency. In addition, these materials are difficult to regenerate after adsorbing perchlorate, which is not conducive to reuse. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide the application of magnetic nanoparticles modified with graphene oxide / metal organic framework as a perchlorate extraction material in view of the shortcomings of the prior art. The material has magnetic ferroferric oxide as the core and a composite functional group composed of graphene oxide and metal organic framework material on the surface. The material is used for extracting perchlorate and has the advantages of fast extraction speed, high extraction efficiency, easy regeneration, etc.

[0005] In order to solve the technical problem raised by the present invention, the present invention provides the application of magnetic nanoparticles modified by graphene oxide / metal organic framework as perchlorate extraction materials, and the magnetic nanoparticles Fe3O4@GO@MIL-53(Al)-NH2 modified by graphene oxide / metal organic framework are added to perchlorate wastewater, and the perchlorate is quickly extracted under the action of external mechanical stirring, and then the Fe3O4@GO@MIL-53(Al)-NH2 after use is separated and recovered by means of a magnetic field to obtain purified water.

[0006] In the above scheme, the Fe3O4@GO@MIL-53(Al)-NH2 is composited with magnetic ferroferric oxide, graphene oxide and metal organic framework material MIL-53(Al)-NH2, which has magnetic ferroferric oxide as the core and a composite functional group composed of graphene oxide and MIL-53(Al)-NH2 on the surface.

[0007] In the above scheme, the particle size of the Fe3O4@GO@MIL-53(Al)-NH2 is 5-25nm, and the specific surface area is 80-120m 2 / g, and the inner diameter of the pores is 1-1.3nm.

[0008] In the above scheme, the perchlorate wastewater mainly comes from fireworks and firecracker enterprises, with a pH of 6-8 and a perchlorate concentration of 100-200 μg / L.

[0009] Furthermore, the perchlorate is one or more of sodium perchlorate, potassium perchlorate, and lithium perchlorate.

[0010] In the above scheme, the dosage of Fe3O4@GO@MIL-53(Al)-NH2 in perchlorate wastewater is 1-2 g / L, the extraction amount of perchlorate is 80-90 μg / g, and the removal efficiency is 80-90%.

[0011] In the above scheme, the extraction temperature of the extraction is 20-25°C, the extraction time is 2-3min, and the mechanical stirring rate during the extraction is 600-800rpm.

[0012] In the above scheme, the preparation method of Fe3O4@GO@MIL-53(Al)-NH2 comprises the following steps:

[0013] 1) dissolving ferric chloride and ferric chloride in water, heating to the reaction temperature under nitrogen protection, then dropping ammonia water therein to react, washing the product with water to neutrality after the reaction, and drying to obtain magnetic nanoparticles Fe3O4;

[0014] 2) dissolving magnetic nanoparticles Fe3O4 and 3-aminopropyltrimethoxysilane in an ethanol aqueous solution, heating to a reaction temperature under weakly acidic conditions, and then adding graphene oxide to continue the reaction. After the reaction is completed, the product is washed with methanol and water in turn, and dried to obtain graphene oxide-modified magnetic nanoparticles Fe3O4@GO;

[0015] 3) Add graphene oxide modified magnetic nanoparticles Fe3O4@GO, aluminum chloride and 2-aminoterephthalic acid into water for ultrasonic dispersion, and then heat to reaction temperature for reaction. After the reaction, wash the product with water and N,N-dimethylformamide in turn, and dry to obtain graphene oxide / metal organic framework modified magnetic nanoparticles Fe3O4@GO@MIL-53(Al)-NH2.

[0016] Furthermore, in step 1), the molar ratio of ferric chloride to ferric chloride is 1:(0.4-0.5), and the volume ratio of the molar amount of ferric chloride to the dissolving water is 1 mol:(250-500) mL.

[0017] Furthermore, the mass fraction of the ammonia water is 25-28%, and the volume ratio of the molar amount of ferric chloride to the ammonia water is 1 mol: (20-25) mL.

[0018] Furthermore, the reaction temperature in step 1) is 80-90°C, and the reaction time is 10-12h.

[0019] Furthermore, the drying in step 1), step 2) and step 3) is vacuum drying, and the drying temperature is 60-70°C.

[0020] Furthermore, the mass ratio of the magnetic nanoparticles Fe3O4, 3-aminopropyltrimethoxysilane and graphene oxide is 1:(2.5-3.0):(0.5-0.8).

[0021] Furthermore, the volume fraction of the ethanol aqueous solution is 40-60%, and the volume ratio of the mass of the magnetic nanoparticles Fe3O4 to the ethanol aqueous solution is 1g:(100-150)mL.

[0022] Furthermore, the weakly acidic condition is pH 4-5, and the pH is adjusted by 1-2 mol / L glacial acetic acid.

[0023] Furthermore, the reaction temperature in step 2) is 60-70° C., the reaction is carried out for 10-12 hours before adding graphene oxide, and the reaction is continued for 10-12 hours after adding graphene oxide.

[0024] Furthermore, the mass ratio of the graphene oxide modified magnetic nanoparticles Fe3O4@GO, aluminum chloride and 2-aminoterephthalic acid is 1:(0.7-0.8):(0.5-0.6).

[0025] Furthermore, in step 3), the volume ratio of the mass of the graphene oxide modified magnetic nanoparticles Fe3O4@GO to the reaction water is 1 g: (80-100) mL.

[0026] Furthermore, the reaction temperature in step 3) is 150-160°C, and the reaction time is 10-12h.

[0027] In the above scheme, the used Fe3O4@GO@MIL-53(Al)-NH2 is regenerated by the following method: the used Fe3O4@GO@MIL-53(Al)-NH2 is added to the eluent, the perchlorate is eluted in an ultrasonic cleaner, and then separated and recovered by means of a magnetic field, and dried to obtain the regenerated Fe3O4@GO@MIL-53(Al)-NH2.

[0028] Furthermore, the eluent is a potassium chloride aqueous solution with a concentration of 10-50 mmol / L.

[0029] Furthermore, the mass ratio of the used Fe3O4@GO@MIL-53(Al)-NH2 to the volume ratio of the eluent is 1 g:(10-20) mL.

[0030] Furthermore, the elution time of the used Fe3O4@GO@MIL-53(Al)-NH2 in an ultrasonic cleaner is 30-60 minutes.

[0031] In the above scheme, the amount of perchlorate extracted by the used Fe3O4@GO@MIL-53(Al)-NH2 after regeneration is more than 80% of that of the unused Fe3O4@GO@MIL-53(Al)-NH2, and it can be regenerated 5-10 times.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1) The present invention prepares a new graphene oxide (GO) / metal organic framework (MOFs) modified magnetic nanoparticles, which combine the advantages of GO and MOFs, and have the advantages of large specific surface area and small pore inner diameter. It is used as an extraction material for perchlorate in perchlorate wastewater. Compared with existing adsorption materials such as activated carbon, carbon nanotubes, chitosan, etc., it has obvious advantages such as more surface functional groups, fast removal speed, high removal efficiency, simple operation, and easy regeneration.

[0034] 2) In order to improve the adsorption rate, the present invention modifies the surface of the magnetic ferroferric oxide core with a composite functional group composed of graphene oxide and a metal organic framework material; since the surface of the magnetic nanoparticle Fe3O4 itself has no functional group, the Fe3O4@GO synthesized on this basis has poor interaction force, so a layer of organic silicon coating is wrapped on the surface of Fe3O4 by 3-aminopropyltrimethoxysilane, and the amino groups on the surface are easy to chemically react with polar groups such as hydroxyl, carboxyl and epoxy glue on the surface of GO, thereby improving the reaction efficiency and stability of Fe3O4@GO; then, aluminum oxide and 2-aminoterephthalic acid are selected to synthesize MOFs (MIL-53(Al)-NH2), which has good water stability. At the same time, the presence of amino groups in MIL-53(Al)-NH2 helps it to chemically react with hydroxyl and carboxyl groups in Fe3O4@GO and enhances the conjugation effect between the nanoparticles and the lone pair of electrons in the perchlorate ion, thereby improving the reaction efficiency of Fe3O4@GO@MIL-53(Al)-NH2 and the stability of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the TEM image of Fe3O4@GO@MIL-53(Al)-NH2 prepared in Example 1 of the present invention.

[0036] Figure 2 FTIR graphs of Fe3O4@GO and Fe3O4@GO@MIL-53(Al)-NH2 prepared in Example 1 of the present invention.

[0037] Figure 3 XRD patterns of Fe3O4@GO and Fe3O4@GO@MIL-53(Al)-NH2 prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0039] Example 1

[0040] The method for preparing magnetic nanoparticles modified with graphene oxide / metal organic framework in this embodiment comprises the following steps:

[0041] 1) 0.4 mol of ferric chloride and 0.2 mol of ferric chloride were dissolved in 200 mL of pure water, and the temperature was raised to 85°C under nitrogen protection, and then 10 mL of ammonia water was added dropwise thereto and reacted for 12 hours. The mass fraction of ammonia water used was 25%. After the reaction, the product was washed with water until neutral, and dried in a vacuum drying oven at 60°C to obtain magnetic nanoparticles Fe3O4;

[0042] 2) 1 g of magnetic nanoparticles Fe3O4 and 3 g of 3-aminopropyltrimethoxysilane were dissolved in 150 mL of ethanol aqueous solution, the volume fraction of the ethanol aqueous solution used was 50%, the pH of the system was adjusted to 4 with 1 mol / L glacial acetic acid, and then the temperature was raised to 60°C for reaction for 12 h, and then 0.5 g of graphene oxide was added to continue the reaction for 12 h. After the reaction, the product was washed with methanol and pure water in turn, and dried in a vacuum drying oven at 60°C to obtain graphene oxide-modified magnetic nanoparticles Fe3O4@GO;

[0043] 3) 1.4 g Fe3O4@GO, 1 g aluminum chloride and 0.8 g 2-aminoterephthalic acid were added to 120 mL water for ultrasonic dispersion, and then heated to 150 ° C in a hydrothermal reactor for reaction for 12 h. After the reaction, the product was washed with pure water and N, N-dimethylformamide in turn, and dried in a vacuum drying oven at 60 ° C to obtain graphene oxide / metal organic framework modified magnetic nanoparticles Fe3O4@GO@MIL-53(Al)-NH2.

[0044] Figure 1 This is the TEM image of Fe3O4@GO@MIL-53(Al)-NH2 prepared in this example. It can be seen from the figure that Fe3O4@GO@MIL-53(Al)-NH2 has uniform size and particle size of 5-25nm. After testing, its specific surface area is 86.56m 2 / g, and the inner diameter of the pores is 1.0-1.2nm.

[0045] Figure 2 FTIR images of Fe3O4@GO and Fe3O4@GO@MIL-53(Al)-NH2 prepared in this example. The FTIR image of Fe3O4@GO@MIL-53(Al)-NH2 shows the peak at 580 cm -1 The absorption peak is the Fe-O stretching vibration peak in Fe3O4, 3382cm -1 and 3496cm -1 OH and NH stretching vibration peaks, 1574 cm -1 and 1388cm -1 They are C=O and CO stretching vibration peaks respectively. These characteristic absorption peaks indicate that Fe3O4@GO@MIL-53(Al)-NH2 was successfully prepared on the Fe3O4 surface.

[0046] Figure 3The XRD patterns of Fe3O4@GO and Fe3O4@GO@MIL-53(Al)-NH2 prepared in this example show that the spectra of Fe3O4@GO and Fe3O4@GO@MIL-53(Al)-NH2 are in good agreement, indicating that Fe3O4@GO@MIL-53(Al)-NH2 was successfully synthesized on the surface of Fe3O4@GO and the crystal structure did not undergo significant changes.

[0047] The Fe3O4@GO@MIL-53(Al)-NH2 prepared in this embodiment is used as a perchlorate extraction material in the treatment of perchlorate wastewater. The perchlorate wastewater to be treated comes from a fireworks and firecracker enterprise, with a pH of 7 and a temperature of 25°C. The perchlorates contained are sodium perchlorate, ammonium perchlorate and lithium perchlorate, etc., and the perchlorate concentration is 200μg / L. The application method is: add Fe3O4@GO@MIL-53(Al)-NH2 to the perchlorate wastewater to be treated, with a dosage of 2g / L, extract for 2min at a stirring rate of 700rpm, and then separate and recover the used Fe3O4@GO@MIL-53(Al)-NH2 by means of a magnetic field to obtain purified water.

[0048] After testing, the extraction amount of perchlorate by Fe3O4@GO@MIL-53(Al)-NH2 was 83μg / g, the perchlorate concentration in the purified water was 34μg / L, and the removal rate was 83%.

[0049] The used Fe3O4@GO@MIL-53(Al)-NH2 was regenerated by adding 1 g of used Fe3O4@GO@MIL-53(Al)-NH2 into 20 mL of 10 mmol / L potassium chloride aqueous solution, eluting in an ultrasonic cleaner for 60 min, then separating and recovering by means of a magnetic field, and drying in a vacuum drying oven at 60°C to obtain regenerated Fe3O4@GO@MIL-53(Al)-NH2.

[0050] The regenerated Fe3O4@GO@MIL-53(Al)-NH2 was again used as a perchlorate extraction material for the treatment of perchlorate wastewater. The application conditions were the same as the first application. After testing, the regenerated Fe3O4@GO@MIL-53(Al)-NH2 had an extraction amount of 78.5 μg / g of perchlorate, which was 94.6% of the unused Fe3O4@GO@MIL-53(Al)-NH2, and still maintained excellent extraction performance.

[0051] Example 2

[0052] The method for preparing magnetic nanoparticles modified with graphene oxide / metal organic framework in this embodiment comprises the following steps:

[0053] 1) Dissolve 0.5 mol of ferric chloride and 0.23 mol of ferric chloride in 250 mL of pure water, heat to 85°C under nitrogen protection, then drop 12 mL of ammonia water and react for 12 hours. The mass fraction of ammonia water used is 25%. After the reaction, wash the product with water until it is neutral, and dry it in a vacuum drying oven at 60°C to obtain magnetic nanoparticles Fe3O4;

[0054] 2) 2 g of magnetic nanoparticles Fe3O4 and 5 g of 3-aminopropyltrimethoxysilane were dissolved in 200 mL of ethanol aqueous solution, the volume fraction of the ethanol aqueous solution used was 50%, the pH of the system was adjusted to 4 with 1 mol / L glacial acetic acid, and then the temperature was raised to 60°C for reaction for 12 h, and then 1.2 g of graphene oxide was added and the reaction was continued for 12 h. After the reaction was completed, the product was washed with methanol and pure water in turn, and dried in a vacuum drying oven at 60°C to obtain graphene oxide-modified magnetic nanoparticles Fe3O4@GO;

[0055] 3) 2 g Fe3O4@GO, 1.5 g aluminum chloride and 1 g 2-aminoterephthalic acid were added to 200 mL water for ultrasonic dispersion, and then heated to 150 °C in a hydrothermal reactor for reaction for 12 h. After the reaction, the product was washed with pure water and N,N-dimethylformamide in turn, and dried in a vacuum drying oven at 60 °C to obtain graphene oxide / metal organic framework modified magnetic nanoparticles Fe3O4@GO@MIL-53(Al)-NH2.

[0056] The Fe3O4@GO@MIL-53(Al)-NH2 prepared in this embodiment is used as a perchlorate extraction material in the treatment of perchlorate wastewater. The perchlorate wastewater to be treated comes from a fireworks and firecracker enterprise, with a pH of 7 and a temperature of 25°C. The perchlorates contained are sodium perchlorate, ammonium perchlorate and lithium perchlorate, etc., and the perchlorate concentration is 100μg / L. The application method is: add Fe3O4@GO@MIL-53(Al)-NH2 to the perchlorate wastewater to be treated, with a dosage of 1g / L, extract for 2min at a stirring rate of 800rpm, and then separate and recover the used Fe3O4@GO@MIL-53(Al)-NH2 with the help of a magnetic field to obtain purified water.

[0057] After testing, the extraction amount of perchlorate by Fe3O4@GO@MIL-53(Al)-NH2 was 81.6μg / g, the perchlorate concentration in the purified water was 18.4μg / L, and the removal rate was 81.6%.

[0058] Comparative Example 1

[0059] The difference between Comparative Example 1 and Example 1 is that the metal organic framework material is MOF-199.

[0060] That is, step 3) is adjusted as follows: 0.52 g of 1,3,5-trimethylbenzenecarboxylic acid, 0.8 g of Cu(OAc)·H2O and 1 g of Fe3O4@GO are weighed and dissolved in 36 mL of a mixed solvent (DMF / ethanol / pure water, 1 / 1 / 1, v / v / v). After mixing evenly, 1 mL of triethylamine is added and stirred at room temperature for 24 h. After stirring, the mixture is washed with DMF and dried in a vacuum drying oven at 60 °C to obtain the product Fe3O4@GO@MOF-199.

[0061] The prepared Fe3O4@GO@MOF-199 was used as a perchlorate extraction material for the treatment of perchlorate wastewater. The application conditions were consistent with those in Example 1. After testing, the adsorption capacity of perchlorate by Fe3O4@GO@MOF-199 was 50.5 μg / g, the perchlorate concentration in the purified water was 99 μg / L, and the removal rate was only 50.5%, which was not a good effect.

[0062] The above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above descriptions. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. Application of graphene oxide / metal organic framework modified magnetic nanoparticles as perchlorate extraction material, characterized in that: The application method is as follows: adding graphene oxide / metal organic framework modified magnetic nanoparticles Fe3O4@GO@MIL-53(Al)-NH2 into perchlorate wastewater, extracting perchlorate, and then separating and recovering the used Fe3O4@GO@MIL-53(Al)-NH2 by means of a magnetic field to obtain purified water; The particle size of the Fe3O4@GO@MIL-53(Al)-NH2 is 5-25nm, and the specific surface area is 80-120m 2 / g, the inner diameter of the pores is 1-1.3nm. It has magnetic Fe3O4 as the core, and composite graphene oxide and metal-organic framework material MIL-53(Al)-NH2 form spherical particles with pores.

2. The use of the graphene oxide / metal organic framework modified magnetic nanoparticles as a perchlorate extraction material according to claim 1, characterized in that: The preparation method of the Fe3O4@GO@MIL-53(Al)-NH2 comprises the following steps: 1) After dissolving ferric chloride and ferric chloride in water, the temperature is raised to the reaction temperature under a protective atmosphere, and then ammonia water is added dropwise to react to obtain magnetic nanoparticles Fe3O4; 2) dissolving Fe3O4 and 3-aminopropyltrimethoxysilane in an ethanol aqueous solution, heating to a reaction temperature under weakly acidic conditions to react, and then adding graphene oxide to continue the reaction to obtain graphene oxide-modified magnetic nanoparticles Fe3O4@GO; 3) Fe3O4@GO, aluminum chloride and 2-aminoterephthalic acid were added to water for ultrasonic dispersion and then heated for reaction to obtain graphene oxide / metal organic framework modified magnetic nanoparticles Fe3O4@GO@MIL-53(Al)-NH2.

3. The use of the graphene oxide / metal organic framework modified magnetic nanoparticles as a perchlorate extraction material according to claim 2, characterized in that: In step 1), the molar ratio of ferric chloride to ferric chloride is 1:(0.4-0.5), the volume ratio of the molar amount of ferric chloride to ammonia water is 1 mol:(20-25) mL, the reaction temperature is 80-90° C., and the reaction time is 10-12 h.

4. The use of the graphene oxide / metal organic framework modified magnetic nanoparticles as a perchlorate extraction material according to claim 2, characterized in that: In step 2), the mass ratio of Fe3O4, 3-aminopropyltrimethoxysilane and graphene oxide is 1:(2.5-3.0):(0.5-0.8), the weakly acidic condition is pH 4-5, the reaction temperature is 60-70°C, and after reacting for 10-12 hours, graphene oxide is added and the reaction is continued for 10-12 hours.

5. The use of the graphene oxide / metal organic framework modified magnetic nanoparticles as a perchlorate extraction material according to claim 2, characterized in that: In step 3), the mass ratio of Fe3O4@GO, aluminum chloride and 2-aminoterephthalic acid is 1:(0.7-0.8):(0.5-0.6), heated to a temperature of 150-160°C, and the reaction time is 10-12h.

6. The use of the graphene oxide / metal organic framework modified magnetic nanoparticles as a perchlorate extraction material according to claim 1, characterized in that: The pH of the perchlorate wastewater is 6-8, and the perchlorate contained therein is one or more of sodium perchlorate, potassium perchlorate, and lithium perchlorate, and the perchlorate concentration is 100-200 μg / L; the dosage of the Fe3O4@GO@MIL-53(Al)-NH2 in the perchlorate wastewater is 1-2 g / L, and the removal efficiency of perchlorate is 80-90%.

7. The use of the graphene oxide / metal organic framework modified magnetic nanoparticles as a perchlorate extraction material according to claim 1, characterized in that: The extraction temperature of the extraction is 20-25° C., the extraction time is 2-3 min, and the extraction amount of perchlorate by Fe3O4@GO@MIL-53(Al)-NH2 is 80-90 μg / g.

8. The use of the graphene oxide / metal organic framework modified magnetic nanoparticles as a perchlorate extraction material according to claim 1, characterized in that: The used Fe3O4@GO@MIL-53(Al)-NH2 is regenerated by the following method: using potassium chloride aqueous solution as eluent, adding the used Fe3O4@GO@MIL-53(Al)-NH2 to the eluent, eluting perchlorate in an ultrasonic cleaner, and then separating and recovering it with the help of a magnetic field to obtain regenerated Fe3O4@GO@MIL-53(Al)-NH2.

9. The use of the graphene oxide / metal organic framework modified magnetic nanoparticles as a perchlorate extraction material according to claim 8, characterized in that: The concentration of the potassium chloride aqueous solution is 10-50 mmol / L, and the elution time is 30-60 min; the amount of perchlorate extracted by the regenerated Fe3O4@GO@MIL-53(Al)-NH2 is more than 80% of that of the unused Fe3O4@GO@MIL-53(Al)-NH2.

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