Preparation method and application of acanthosphere shell-shaped Fe3O4-coated MnO2

Abstract

The invention relates to a preparation method and application of an acanthosphere shell-shaped Fe3O4-coated MnO2 catalyst. The method mainly comprises the following steps: taking Fe3O4 prepared by taking steel pickling waste liquid as a raw material as a precursor, taking potassium permanganate and hydrochloric acid as raw materials, and reacting for 6 hours at 120 DEG C through a hydrothermal method to obtain the acanthosphere shell-shaped Fe3O4-coated MnO2 catalyst. According to the invention, Fe3O4 and MnO2 are compounded, so that not only is the defect that Fe3O4 is easy to oxidize and agglomerate in the prior art overcome, but also the specific surface area and the stability of the material are improved; the acanthosphere shell-shaped Fe3O4-coated MnO2 catalyst prepared by the preparation method disclosed by the invention is applied to the treatment of activating persulfate to degrade sulfamethoxazole antibiotic wastewater, the antibiotic wastewater can be completely removed within 30 minutes, the wastewater treatment cost is remarkably reduced, and the acanthosphere shell-shaped Fe3O4-coated MnO2 catalyst has good reusability and stability.

Description

Technical Field

[0001] The invention belongs to the field of environmental functional materials, and relates to a method for preparing a spherical shell-shaped Fe3O4@MnO2 catalyst, and application of the catalyst in catalytic degradation of sulfamethoxazole wastewater by activated persulfate. Background Art

[0002] In recent years, with the rapid development of industry and medical industry, water pollution caused by emerging pollutants such as antibiotics, disinfection by-products and endocrine disruptors has attracted more and more attention. Sulfamethoxazole is one of the typical sulfonamide antibiotics and is widely used in the prevention and treatment of infectious diseases due to its antibacterial properties. In view of the strong bacterial resistance, weak biodegradability and potential carcinogenicity of sulfamethoxazole, it may cause a serious public crisis. They have high antibacterial properties and are difficult to biodegrade. Traditional sewage biological treatment methods cannot completely degrade them, which is extremely harmful to water pollution. Therefore, it is urgent to remove the pollution caused by sulfamethoxazole in the water environment.

[0003] At present, there are biological methods, physical adsorption methods and advanced oxidation methods for removing antibiotics from water environments. It is difficult for traditional biological treatment processes to completely degrade sulfonamide antibiotics. However, advanced oxidation processes have been proven to effectively degrade pollutants. In particular, persulfate-based advanced oxidation processes have quickly become a potential pollutant treatment method due to their unique advantages in storage, transportation and applicability. However, single persulfate does not have oxidation ability and requires the addition of an active agent for activation under certain conditions. Therefore, the selection of active agents is the key to the effective application of persulfate advanced oxidation technology.

[0004] Iron-based materials represented by nano-Fe3O4 have certain prospects in the field of removing antibiotic wastewater, because magnetic nanoparticles can be easily separated from water under the action of an external magnetic field and have a high magnetic susceptibility. Fe3O4 not only has a high specific surface area, but also has a unique crystal structure. Unfortunately, the disadvantages of Fe3O4 nanoparticles with high specific surface area and magnetism, such as easy agglomeration, poor stability and easy oxidation, limit its application in the field of catalysis. MnO2, as an environmentally friendly adsorbent, has the characteristics of large specific surface area, low price and low zero charge point. Its good modified surface performance can meet the needs of practical applications. Using MnO2 to modify the surface of Fe3O4 can not only improve the disadvantage of easy agglomeration of Fe3O4, but also improve the catalytic performance by using its surface functional groups. So far, the method of activating persulfate to degrade sulfamethoxazole with Fe3O4@MnO2 catalyst has not been reported, which is of great significance for broadening the application scope of persulfate-based advanced oxidation processes in the field of environmental pollutant treatment. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing a Fe3O4@MnO2 catalyst with excellent catalytic performance and high stability and its application in sewage treatment, so as to achieve efficient degradation treatment of sulfamethoxazole in water.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for preparing a spherical shell-shaped Fe3O4@MnO2 catalyst, the method comprising the following steps:

[0008] In the present invention, Fe3O4 prepared from iron and steel pickling waste liquid is used as a precursor, potassium permanganate and hydrochloric acid are used as raw materials, and spherical shell-like Fe3O4@MnO2 is synthesized by a hydrothermal method.

[0009] Potassium permanganate and hydrochloric acid are added into water to fully react, and then Fe3O4 prepared from steel pickling waste liquid as raw material is added into the mixed solution. After ultrasonic dispersion, hydrothermal reaction is carried out, and solid product is separated out after the reaction is completed.

[0010] Preferably, the Fe3O4 is prepared by first diluting the steel pickling waste liquid by 10 times, adjusting the solution pH to 5.5 to remove impurities, and then adjusting the Fe 3+ and Fe 2+ The ratio is 1.8:1.0~2.0:1.0, stirring for 30 minutes, and after the reaction is completed, the solid product is separated out to obtain.

[0011] Preferably, the molar ratio of potassium permanganate and hydrochloric acid added is 1:4, n[Fe]:n[Mn]=2:1.

[0012] Preferably, the ultrasonic time is 10 min.

[0013] Preferably, the temperature of the hydrothermal reaction is 120° C. and the time is 6 hours.

[0014] Preferably, the separated solid product is washed three times with distilled water and ethanol alternately, dried under vacuum at 60° C. for 3 h, ground with an agate mortar and stored in a vacuum-sealed state.

[0015] The beneficial effects of the present invention are:

[0016] (1) Nano-Fe3O4 was prepared from steel pickling waste liquid, realizing the high-value utilization of steel pickling waste liquid.

[0017] (2) The problem of magnetic nanoparticle agglomeration can be improved by compounding MnO2, and the material's ability to activate persulfate can be enhanced;

[0018] (3) In the treatment of sulfamethoxazole antibiotic wastewater, the treatment cost is reduced and the degradation efficiency of sulfamethoxazole is improved. Studies have shown that the prepared Fe3O4@MnO2 can completely remove sulfamethoxazole in simulated wastewater within 30 minutes without causing secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 This is a SEM image of the spherical shell-shaped Fe3O4@MnO2 material of Example 1 of the present invention;

[0021] Figure 2 This is the XRD diagram of the spherical shell Fe3O4@MnO2 of Example 1 of the present invention;

[0022] Figure 3 The N2 adsorption-desorption curve and pore size distribution diagram of the spherical shell Fe3O4@MnO2 of Example 1 of the present invention;

[0023] Figure 4 This is the VSM diagram of the spherical shell Fe3O4@MnO2 of Example 1 of the present invention;

[0024] Figure 5 The effects of different materials in Example 2 of the present invention on the degradation of sulfamethoxazole by activated persulfate;

[0025] Figure 6 The figure shows the effect of different solution pH values ​​on the degradation of sulfamethoxazole by activated persulfate in Example 3 of the present invention.

[0026] Figure 7 The different amounts of inorganic anions and natural organic matter (Cl-, NO3 - 、SO4 2- 、HCO3 - 、H2PO4 - and HA) on the degradation of sulfamethoxazole by activated persulfate. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments.

[0028] Example 1

[0029] The preparation method of the spherical shell Fe3O4@MnO2 catalyst comprises the following steps:

[0030] (1) Fe3O4 is prepared by co-precipitation method: ① Impurity removal: Take 50mL of steel pickling waste liquid and dilute it to 500mL in a beaker, adjust the solution pH to 5.5 with NaOH and stir it in a water bath at 70℃ for 30min, then place the solution to age for 30min. After cooling, filter it with slow filter paper to obtain a brown turbid solution, and then filter it with a microporous filter membrane to obtain a clear light green solution after pretreatment. ② Stir the impurity-removed steel pickling waste liquid at 70℃, add a certain amount of H2O2 at a uniform rate, and Fe 3+ and Fe 2+ The molar ratio of is adjusted to 1.8:1.0-2.0:1.0. Then adjust pH to 10 with NaOH and stir for 30 minutes. When the solution is cooled to room temperature, separate it under an external magnetic field, wash it three times with anhydrous ethanol and deionized water, and finally dry it in a vacuum drying oven at 60°C.

[0031] (2) Synthesis of Fe3O4@MnO2: 0.51g KMnO4 was added to 35mL deionized water, and 0.7mL HCl (37wt%) was added dropwise and stirred for 15min. Then 0.18g S-Fe3O4 prepared from steel pickling waste liquid was added and stirred for 10min. The above mixture was transferred to a 50mL high-pressure reactor and reacted at 120℃ for 6h. After the solution was cooled to room temperature, the brown precipitate was separated under an external magnetic field, washed three times with anhydrous ethanol and deionized water respectively, and finally dried at 60℃ in a vacuum drying oven to obtain Fe3O4@MnO2.

[0032] Example 2

[0033] Fe3O4@MnO2 composite material prepared by Example 1 and Fe3O4 and MnO2 as contrast are respectively used as activators, and activated persulfate degrades sulfamethoxazole in water. Specific steps are: take 100mL sulfamethoxazole with a concentration of 20mg / L, add 0.2g / L catalyst thereto and add 0.5mM persulfate to initiate degradation reaction. Under the effect of mechanical stirring, stir 30min at 200r / min, sample within a specific time, add 200uL concentration of 80mM sodium thiosulfate to sample and quench, and use high performance liquid chromatograph to measure the degradation rate of sulfamethoxazole. At the same time, blank without catalyst is used as control. The sulfamethoxazole concentration of the test solution changes with the degradation time during degradation.

[0034] Draw the degradation curve as Figure 5As shown in the data, it can be seen that the Fe3O4@MnO2 composite material prepared in Example 1 exhibits better activation and degradation performance, and the degradation rate of sulfamethoxazole can reach 100% in 30 minutes, thereby confirming that the active sites in the Fe3O4@MnO2 composite material can promote the decomposition of persulfate and produce active substances.

[0035] Example 3

[0036] Study on the influence of different pH values ​​on the degradation of sulfamethoxazole by persulfate activation of the Fe3O4@MnO2 composite material prepared in Example 1.

[0037] Fe3O4@MnO2 with a concentration of 0.2 g / L and persulfate with a volume of 100 mL and pH values ​​of 3, 5, 7.2, 9, and 11 were added to five sulfamethoxazole wastewaters, respectively. The mixture was stirred at 200 r / min for 30 min under mechanical stirring. Samples were taken within a specific time and quenched with 200 uL of 80 mM sodium thiosulfate. The degradation rate of sulfamethoxazole was determined using high performance liquid chromatography.

[0038] Figure 6 The degradation of sulfamethoxazole by Fe3O4@MnO2 composite material activated by persulfate at different reaction pH values. As shown in the figure, the Fe3O4@MnO2 composite catalyst shows an excellent degradation rate (>94%) in a wide pH range (3-9). The degradation effect of sulfamethoxazole is not good under alkaline conditions because persulfate will decompose into SO5 2- Especially at pH = 11, the degradation rate of sulfamethoxazole was only 55.98%.

[0039] Example 4

[0040] The Fe3O4@MnO2 composite material prepared in Example 1 was added to 100 mL of 20 mg / L sulfamethoxazole, to which 0.2 g / L of catalyst and 0.5 mM of persulfate were added, and different amounts of inorganic anions and natural organic matter (Cl - 、NO3 - 、SO4 2- 、HCO3 - 、H2PO4 - The mixture was stirred at 200r / min for 30min under mechanical stirring, and 200uL of 80mM sodium thiosulfate was added to the sample for quenching. The degradation rate of sulfamethoxazole was determined by high performance liquid chromatography.

[0041] The results are as follows Figure 7 As shown, after adding Cl - and NO3 - When SO4 2- 、HCO3 - and H2PO4 - When the degradation efficiency is significantly reduced, the reason may be that SO4 2- 、HCO3 - and H2PO4 - The inhibitory effect of persulfate on the activation of Fe3O4@MnO2 is obvious, and the inhibitory effect becomes more obvious with the increase of concentration. However, the addition of HA has a certain promoting effect, which accelerates the degradation rate of sulfamethoxazole.

[0042] In summary, the Fe3O4@MnO2 catalyst of the present invention has excellent activation performance, has certain magnetic properties and is easier to recover, and has excellent stability. Therefore, the Fe3O4@MnO2 catalyst has a good application prospect in the treatment of sulfamethoxazole organic wastewater.

[0043] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a spherical shell Fe3O4@MnO2 catalyst, characterized in that: Spiny spherical shell Fe3O4@MnO2 was synthesized by hydrothermal method using Fe3O4 prepared from steel pickling waste liquid as precursor and potassium permanganate and hydrochloric acid as raw materials.

2. The method for preparing the spherical shell Fe3O4@MnO2 catalyst according to claim 1, characterized in that: Potassium permanganate and hydrochloric acid are added into water to fully react, and then Fe3O4 prepared from steel pickling waste liquid as raw material is added into the mixed solution. After ultrasonic dispersion, hydrothermal reaction is carried out, and solid product is separated out after the reaction is completed.

3. The method for preparing the spherical shell Fe3O4@MnO2 catalyst according to claim 2, characterized in that: First, the iron and steel pickling waste liquid was diluted 10 times, the solution pH was adjusted to 5.5 to remove impurities, and then the Fe 3+ and Fe 2+ The ratio is 1.8:1.0~2.0:1.0, stirring for 30 minutes, and after the reaction is completed, the solid product is separated to obtain Fe3O4.

4. The method for preparing the spherical shell Fe3O4@MnO2 catalyst according to claim 2, characterized in that: The molar ratio of potassium permanganate and hydrochloric acid added was 1:4, n[Fe]:n[Mn]=2:

1.

5. The method for preparing the spherical shell Fe3O4@MnO2 catalyst according to claim 2, characterized in that: The ultrasound time mentioned is 10 min.

6. The method for preparing the spherical shell Fe3O4@MnO2 catalyst according to claim 2, characterized in that: The temperature of the hydrothermal reaction was 120°C and the time was 6 h.

7. The method for preparing the spherical shell Fe3O4@MnO2 catalyst according to claim 2, characterized in that: The material was washed alternately with distilled water and ethanol three times, dried under vacuum at 60 °C for 3 h, ground with an agate mortar and stored in a vacuum-sealed state.

8. Use of the spherical shell-shaped Fe3O4@MnO2 catalyst prepared by the preparation method described in any one of claims 1 to 7 in the treatment of sulfamethoxazole antibiotic wastewater.

9. The use according to claim 8, characterized in that: The method comprises the following steps: mixing a spherical shell Fe3O4@MnO2 catalyst with water containing antibiotics, adding persulfate, initiating a catalytic degradation reaction, and completing the degradation of the antibiotics in the water; the amount of the spherical shell Fe3O4@MnO2 catalyst added is 0.2 g / L; the amount of the persulfate added is 0.5 mM. The spherical shell Fe3O4@MnO2 catalyst is applied to the treatment process of activating persulfate to catalyze the degradation of sulfamethoxazole.

Images