Preparation method and use method of magnetic fenton-like catalytic carbon sheet

Abstract

This invention discloses a method for preparing and using a magnetic Fenton-type catalytic carbon sheet, comprising the following steps: S1, weighing glucose and ferric chloride in a mass ratio of 5:1 and adding them to a 500mL beaker, adding 200mL of purified water, and stirring until completely dissolved; S2, sonicating the solution in a water bath at 80℃ for 3 hours, slowly adding 0.1mmol / L NaOH until the pH value is 9-11, and continuing sonication for 1 hour; S3, pouring the solution into a ceramic double-layer crucible, placing it in a vacuum drying oven and heating it at 102℃ for 24 hours, then calcining it in a muffle furnace at 700-800℃ for 2-5 hours, and removing it after the temperature drops to room temperature; S4, grinding it thoroughly in an agate mortar, passing it through a sieve, washing it successively with pure water and anhydrous ethanol, and magnetically filtering it; S5, placing the filter cake in a vacuum drying oven and drying it at 102℃ for 6 hours. h. Store in a sealed container. The magnetic Fenton-like catalytic carbon sheet prepared by this invention has uniform nano-Fe3O4 particles, high dispersibility, and a high specific surface area, making it valuable for the efficient removal of methylene blue from water.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for preparing magnetic Fenton catalytic carbon sheets and its application. Background Technology

[0002] Textile dyeing and printing wastewater is characterized by its deep color, difficulty in degradation, high toxicity, and high content of organic pollutants. Methylene blue (MB) wastewater, in particular, severely damages the local ecological environment. Therefore, the treatment of dyeing and printing wastewater is a crucial aspect of ensuring water environmental safety. In recent years, commonly used methods for treating dyeing and printing wastewater include adsorption, membrane separation, and oxidation. Advanced oxidation technologies based on hydroxyl radicals (HO·) are widely used in the pretreatment or advanced treatment processes of dyeing and printing wastewater.

[0003] The heterogeneous Fenton oxidation method using nano-Fe3O4 fixes iron within the catalyst, activating H2O2 to generate hydroxyl radicals, exhibiting high removal efficiency for various organic compounds. Furthermore, nano-Fe3O4 composite materials are generally magnetic, facilitating separation and recovery, thus avoiding the generation of large amounts of iron sludge. However, magnetic nano-Fe3O4 particles readily aggregate, significantly reducing their catalytic degradation efficiency during application. Therefore, it is necessary to disperse nano-Fe3O4 particles on a carrier or coat them with polymers, metal oxide shells, etc., to form magnetic composite materials. Existing nano-Fe3O4 powders often produce large amounts of iron sludge during use, resulting in poor wastewater treatment efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and using magnetic Fenton-type catalytic carbon sheets, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a magnetic Fenton-type catalytic carbon sheet includes the following steps:

[0007] S1. Weigh out glucose and ferric chloride in a mass ratio of 5:1 and add them to a 500mL beaker. Add 200mL of purified water and stir until completely dissolved.

[0008] S2. Sonicate the solution in a water bath at 80℃ for 3 hours, then slowly add 0.1 mmol / L NaOH until the pH value is 9-11, and continue sonicating for 1 hour.

[0009] S3. Pour the solution into a ceramic double-layer crucible and place it in a vacuum drying oven at 102°C for 24 hours. Then calcine it in a muffle furnace at 700-800°C for 2-5 hours. Remove it after the temperature drops to room temperature.

[0010] S4. Grind thoroughly in an agate mortar, then wash with pure water and anhydrous ethanol in sequence after passing through a sieve, and filter magnetically.

[0011] S5. Place the filter cake in a vacuum drying oven and dry it at 102℃ for 6 hours, then seal and store it.

[0012] Preferably, the pH value in step S2 is 10-11.

[0013] Preferably, the calcination temperature in step S3 is 700°C.

[0014] Preferably, the calcination time in step S3 is 2 hours.

[0015] Preferably, the screen density in step S4 is 60 mesh.

[0016] Preferably, the washing process in step S4 involves at least three washes.

[0017] A method for using a magnetic Fenton catalytic carbon sheet includes the following steps:

[0018] Take 50 mL of raw water sample and put it into a 50 mL capped plastic tube. Add magnetic Fenton carbon catalyst and H2O2. Shake the sample at a constant temperature of 25℃. Then magnetically separate the supernatant and filter it through a 0.45 μm filter membrane. Measure the concentration of MB. Repeat the process 3 times and calculate the average value and standard deviation of the sample.

[0019] The technical effects and advantages of this invention are as follows:

[0020] 1. Magnetic Fenton-like catalytic carbon sheets prepared by co-precipitation followed by carbonization and calcination have uniform magnetic Fenton-like catalytic particles, high dispersibility, and high specific surface area.

[0021] 2. The decolorization rate of MB can still reach 95.6% after the magnetic Fenton catalytic carbon sheet is recycled 6 times, and it can be quickly separated and recovered under the action of magnetic field, which has the application value of efficiently removing MB from water;

[0022] 3. The decolorization and removal of MB by magnetic Fenton catalytic carbon sheets is the result of the synergistic effect of physical adsorption and catalytic oxidation, and the reaction process for removing MB conforms to a pseudo-second-order kinetic model;

[0023] 4. The iron on the magnetic Fenton catalytic carbon sheet remains on the carbon material after the catalytic oxidation reaction is completed, and is not released into the aqueous solution in large quantities, thus avoiding secondary pollution. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The instruments used in preparation, use, and testing are as follows: muffle furnace (SX-2.5-10, Qingdao Mingbo), vacuum drying oven (DZF-6210, Anhui Ninghuai Instrument), constant temperature shaker (SHZ-82, Shanghai Hetian Science), spectrophotometer (T6 New Century, Shenzhen Purkinje General), pH meter (PHS-3E, Shanghai Leici), X-ray diffractometer (XRD-6000, Shimadzu Corporation, Japan), transmission electron microscope (JEM-200CX, JEOL Corporation, Japan), magnetic measurement system (MPMS-5T, QuantumDesign Corporation, USA), specific surface area analyzer (ASAP 2020V3.00H, Micromeritics Corporation, USA), and atomic absorption spectrometer (AA-7000, Shimadzu Corporation, Japan).

[0026] Example 1:

[0027] This invention provides a method for preparing magnetic Fenton-type catalytic carbon sheets, comprising the following steps:

[0028] S1. Weigh out glucose and ferric chloride in a mass ratio of 5:1 and add them to a 500mL beaker. Add 200mL of purified water and stir until completely dissolved.

[0029] S2. Sonicate the solution in a water bath at 80℃ for 3 hours, then slowly add 0.1 mmol / L NaOH until the pH value is 9-11, and continue sonicating for 1 hour.

[0030] S3. Pour the solution into a ceramic double-layer crucible and place it in a vacuum drying oven at 102°C for 24 hours. Then calcine it in a muffle furnace at 700-800°C for 2-5 hours. Remove it after the temperature drops to room temperature.

[0031] S4. Grind thoroughly in an agate mortar, and after passing through a sieve, wash with pure water and anhydrous ethanol in sequence, and then filter magnetically. The sieve density is 60 mesh, and the washing is performed at least 3 times.

[0032] S5. Place the filter cake in a vacuum drying oven and dry it at 102℃ for 6 hours, then seal and store it.

[0033] The mass ratios of glucose and ferric chloride are shown in Table 1. The composite material obtained with a carbon-to-iron mass ratio of 5:1 has the largest specific surface area and the highest removal efficiency. The recommended standard for iron ions in the "Standards for Drinking Water Quality" (GB5749-2006) is 0.3 mg / L. Therefore, the iron in the composite material is more robust.

[0034]

[0035] Table 1

[0036] The effect of pH on the decolorization rate during coprecipitation in step S2 is shown in Table 2, with the optimal pH value being 10-11.

[0037] serial number pH Decolorization rate (%) 1 pH: 6~7 76.8 2 pH: 8~9 73.1 3 pH: 9~10 90.3 4 pH: 10~11 96.8 5 pH: 11~12 76.5

[0038] Table 2

[0039] The effect of calcination temperature on decolorization rate in step S3 is shown in Table 3. The calcination temperature is 700℃, at which point the Fe3O4 in the composite material has good crystallinity.

[0040] serial number Temperature ℃ Decolorization rate (%) 1 300 56.8 2 400 63.1 3 500 78.2 4 600 80.5 5 700 96.8 6 800 95.3

[0041] Table 3

[0042] The calcination time in step S3 is 2 hours.

[0043] A method for using a magnetic Fenton catalytic carbon sheet includes the following steps:

[0044] Take 50 mL of raw water sample and place it into a 50 mL capped plastic tube. Add magnetic Fenton carbon catalyst and H2O2. After shaking at a constant temperature of 25℃, magnetically separate the supernatant. Filter the supernatant through a 0.45 μm filter membrane and measure the concentration of MB. All experiments were repeated three times, and the average value and standard deviation of the samples were calculated.

[0045] The concentration of MB in the water sample was determined by spectrophotometry at a wavelength of 664 nm. Using purified water as a reference, the MB concentration was calculated using a standard curve method (equation: A = 0.1495m - 0.0168, r = 0.9989). The decolorization rate R and the amount of MB removed by the magnetic Fenton catalytic carbon sheet were calculated using formulas (1) and (2). To further investigate the decolorization and removal mechanism of MB by the magnetic Fenton catalytic carbon sheet, quasi-first-order and quasi-second-order kinetic models were used for process fitting, and the fitting formulas are (3) and (4).

[0046] Formula (1): R = (1 - C t / C0)×100%

[0047] Formula (2): Q = (C0 - C tV / m

[0048] Formula (3): ln(C) e -C t )=ln(C e )-k1t

[0049] Formula (4): C t =k2C e 2 t / (1+C e 2 t)

[0050] In the formula, C0, C t and C e Let be the mass concentrations of MB in the solution at the initial reaction time t and at reaction equilibrium, respectively; V be the solution volume; m be the mass of the composite material; and k1 and k2 be the constants for pseudo-first-order kinetics and pseudo-second-order kinetics, respectively.

[0051] Testing revealed:

[0052] XRD test results show that when the scanning diffraction angle (2θ) is 10°-80°, the 2θ corresponding to the sharp diffraction peaks are 30.24°, 35.82°, 43.18°, 57.78° and 62.66° respectively. According to the standard PDF card (JCPDF65-3107), the diffraction crystal planes of Fe3O4 are (220), (311), (400), (511) and (440) respectively. The diffraction peaks of Fe3O4 are relatively sharp, indicating that Fe3O4 in the composite material has good crystallinity.

[0053] Microstructure of composite materials (TEM)

[0054] TEM results showed that uniformly sized Fe3O4 particles were clearly visible on the magnetic Fenton-like catalytic carbon sheet, with an average diameter of 22 nm. The Fe3O4 particles loaded on the carbon sheet were well dispersed, with only a small amount of particle aggregation. Compared with pure Fe3O4, the newly prepared magnetic Fenton-like catalytic carbon sheet had a specific surface area of ​​183.4 m2 / g, a pore volume of 0.125 cm3 / g, and an average pore size of 32.9 nm, which were 5.8 times, 2.6 times, and 2.2 times that of pure Fe3O4, respectively. The magnetic Fenton-type catalytic carbon sheet exhibits a significant increase in specific surface area, pore volume, and pore size. This indicates that during the preparation process, nano-Fe3O4 particles are deposited and embedded on the porous carbon sheet support. Some iron particles are embedded within the carbon sheet, resulting in good dispersion of the Fe3O4 particles without agglomeration. Simultaneously, the nano-Fe3O4 particles also expand the interlayer spacing of the carbon sheet, preventing further stacking and resulting in a larger specific surface area. The magnetic Fenton-type catalytic carbon sheet demonstrates a strong adsorption capacity for MB. Its well-developed pore structure promotes the diffusion and exchange of MB within the material pores and increases the residence time of MB within the pores, which is more conducive to the oxidation reaction of HO· free radicals.

[0055] The hysteresis loop of the composite material indicates that the magnetic Fenton-like catalytic carbon sheet exhibits strong paramagnetism at room temperature, with a saturation magnetization of 39.52 emu·g. -1 The magnetic separation effect of magnetic Fenton-type carbon catalysts was demonstrated by using neodymium magnets to magnetically separate the reacted mixture. Under the influence of an external magnetic field, the magnetic Fenton-type carbon catalysts quickly aggregated near the neodymium magnets, clarifying the solution. Thanks to their high magnetization, these magnetic Fenton-type carbon catalysts can effectively perform magnetic separation and recovery in wastewater, allowing for recycling and increasing their practical application value.

[0056] In summary, the present invention has the following advantages:

[0057] 1. Magnetic Fenton-like catalytic carbon sheets prepared by co-precipitation followed by carbonization and calcination have uniform magnetic Fenton-like catalytic particles, high dispersibility, and high specific surface area.

[0058] 2. The decolorization rate of MB can still reach 95.6% after the magnetic Fenton catalytic carbon sheet is recycled 6 times, and it can be quickly separated and recovered under the action of magnetic field, which has the application value of efficiently removing MB from water;

[0059] 3. The decolorization and removal of MB by magnetic Fenton catalytic carbon sheets is the result of the synergistic effect of physical adsorption and catalytic oxidation, and the reaction process for removing MB conforms to a pseudo-second-order kinetic model;

[0060] 4. The iron on the magnetic Fenton catalytic carbon sheet remains on the carbon material after the catalytic oxidation reaction is completed, and is not released into the aqueous solution in large quantities, thus avoiding secondary pollution.

[0061] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a magnetic Fenton-type catalytic carbon sheet, characterized in that, Includes the following steps: S1. Weigh out glucose and ferric chloride in a mass ratio of 5:1 and add them to a 500mL beaker. Add 200mL of purified water and stir until completely dissolved. S2. Sonicate the solution in a water bath at 80℃ for 3 hours, then slowly add 0.1 mmol / L NaOH until the pH value is 10-11, and continue sonicating for 1 hour. S3. Pour the solution into a ceramic double-layer crucible and place it in a vacuum drying oven at 102 ℃ for 24 h. Then calcine it in a muffle furnace at 700-800 ℃ for 2-5 h. Take it out after the temperature drops to room temperature. S4. Grind thoroughly in an agate mortar, and after passing through a sieve, wash with pure water and anhydrous ethanol in sequence, and then filter magnetically. The sieve density in step S4 is 60 mesh, and the washing is performed at least 3 times in step S4. S5. The filter cake is placed in a vacuum drying oven and dried at 102℃ for 6 hours, then sealed and stored.

2. The method of using the magnetic Fenton-like catalytic carbon sheet prepared by the method described in claim 1, characterized in that, Includes the following steps: Take 50 mL of raw water sample and put it into a 50 mL capped plastic tube. Add magnetic Fenton carbon catalyst and H2O2. Shake the sample at a constant temperature of 25℃. Then magnetically separate the supernatant and filter it through a 0.45 μm filter membrane. Measure the concentration of MB. Repeat the process 3 times and calculate the average value and standard deviation of the sample.

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