Fe-based charcoal monatomic catalytic membrane as well as preparation method and application thereof

Abstract

The invention provides a Fe-based charcoal monatomic catalytic membrane as well as a preparation method and application thereof, the preparation method comprises the following steps: pickling shrimp powder, washing with water, and drying to obtain pickled biomass; the preparation method comprises the following steps: dissolving melamine in hot water of 80-95 DEG C, and adding ferrous sulfate to obtain a solution A; dissolving cyanuric acid in hot water at 80-95 DEG C to obtain a solution B; adding the solution B into the solution A, stirring, performing suction filtration, and performing vacuum drying to obtain Fe-SOFs; the biomass subjected to acid pickling, KOH and Fe-SOFs are subjected to ball milling for 0.5-2 h, the temperature is increased to 600-900 DEG C, pyrolysis is conducted for 1-3 h, and grinding, acid pickling, water washing and drying are conducted after cooling; and adding the obtained catalyst into an N-methyl pyrrolidone solution of polyvinylidene fluoride, uniformly mixing, dropwise adding onto a carbon felt, and drying in vacuum to obtain the Fe-based charcoal monatomic catalytic membrane. According to the technical scheme, the activation efficiency of persulfate and the degradation rate of aniline are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysts and industrial wastewater treatment, in particular to a Fe-based biochar single-atom catalytic membrane and its preparation method and application. BACKGROUND

[0002] The treatment of aniline pollutants in industrial wastewater is an important challenge in the field of environmental engineering. Such pollutants pose a serious threat to human health and the ecosystem due to their strong toxicity and non-biodegradability. In the current mainstream treatment technologies, physical methods such as adsorption and membrane separation are simple to operate but have fundamental defects such as adsorption saturation requiring regeneration, severe membrane fouling, and inability to achieve pollutant degradation. Biological methods face application bottlenecks such as low treatment efficiency (requiring a 15-20 day cycle) and system instability due to the strong toxicity of aniline substances to microorganisms. In comparison, advanced oxidation technology based on PDS exhibits significant advantages due to the generation of strong oxidizing free radicals (SO4·- and ·OH), but the catalyst system still has key defects: homogeneous catalysts have high activation efficiency but suffer from metal leaching, difficulty in recovery, and narrow pH application range; heterogeneous nanocatalysts can be recovered but are limited by low metal atom utilization, uneven active sites causing side reactions, and easy agglomeration of nanoparticles leading to inactivation. Single-atom catalysts (SACs) are emerging solutions that theoretically achieve 100% atom utilization, but existing Fe-N4 symmetrical structure materials have insufficient PDS activation efficiency due to limited electron transfer, and building asymmetric Fe-Nx sites still faces problems such as complex preparation process (high-temperature carbonization or electrospinning-electrospraying) and high cost. In the field of catalytic membrane technology, traditional electrocatalytic membranes generally have low catalytic activity and limited mass transfer, even though the single-atom TiOxCy electrocatalytic membrane developed by Tsinghua University has a high flux of 8370 Lm –2 h –1 bar –1 , it still has application limitations such as insufficient specificity for aniline substances, reliance on an external electric field (energy consumption 0.022 kWh·m –3 ·order -1 ), and low degradation rate of aniline substances. SUMMARY

[0003] To address the above technical problems, the present application discloses a Fe-based biochar single-atom catalytic membrane and its preparation method and application. The Fe-based biochar single-atom catalytic membrane improves the activation efficiency of persulfate and, when used in combination with persulfate, improves the degradation rate of aniline pollutants.

[0004] To this end, the technical solution adopted by the present application is as follows:

[0005] A preparation method of a Fe-based biochar single-atom catalytic membrane, comprising the following steps:

[0006] Step S1, shrimp meal is pickled, then washed with water and dried to obtain a biomass after pickling;

[0007] Step S2, melamine is dissolved in hot water at 80-95 DEG C, and ferrous sulfate is added to obtain solution A; cyanuric acid is dissolved in hot water at 80-95 DEG C to obtain solution B; solution B is poured into solution A, stirred for 0.5-3h, vacuum filtered, and the filtered solid is vacuum dried to obtain Fe-SOFs;

[0008] Step S3, the pickled biomass, KOH and Fe-SOFs are mixed and ball milled for 0.5-2h to obtain a mixture, wherein the mass ratio of the pickled biomass, KOH and Fe-SOFs is 1:1-2:1.5-2.5, and the Fe element of Fe-SOFs accounts for 0.1-0.15% of the mass of the pickled biomass; the mixture is heated to 600-900 DEG C and pyrolyzed for 1-3h, cooled to room temperature, ground, pickled for 0.5-2h, washed with water and dried to obtain a catalyst Fe-NKBC;

[0009] Step S4, the catalyst Fe-NKBC is added to a polyvinylidene fluoride N-methyl pyrrolidone solution, wherein the mass ratio of the catalyst Fe-NKBC to polyvinylidene fluoride is 2-4:1, and the mixture is uniformly mixed to obtain a catalyst turbid liquid; the catalyst turbid liquid is uniformly dropped onto a carbon felt and vacuum dried to obtain a Fe-based biochar single-atom catalyst film SAFe@GF.

[0010] By adopting the technical scheme, the preparation process of the supramolecular organic framework in step S2 is optimized, the preparation cost is reduced, the process safety is improved, and secondary pollution is reduced.

[0011] By constructing an N / O co-coordinated single-atom Fe catalyst and loading it on a carbon felt, the activation efficiency of PDS (persulfate) is improved, the atomic utilization rate is maximized, the metal dissolution is minimized, and the pH adaptability is optimized, the high activity of the single-atom catalyst is combined with the high efficiency of the membrane separation technology, and an innovative solution is provided for industrial wastewater treatment.

[0012] Step S2 is the preparation of the supramolecular organic framework, which optimizes the process, reduces the preparation cost, improves the process safety and reduces the secondary pollution.

[0013] As a further improvement of the application, in step S2, the ratio of the amount of substance of melamine in solution A to the amount of substance of cyanuric acid in solution B is 0.9-1.1:1. Further, in step S2, the ratio of the amount of substance of melamine in solution A to the amount of substance of cyanuric acid in solution B is 1:1.

[0014] As a further improvement of the present application, the mass ratio of the acid-washed biomass, KOH and Fe-SOFs is 1:1.5:2, and the Fe element of the Fe-SOFs accounts for 0.13% of the mass of the biomass.

[0015] As a further improvement of the present application, in step S3, the heating rate is 2-10℃ / min. In step S3, the heating rate is 5℃ / min.

[0016] As a further improvement of the present application, in step S3, after water washing and drying, the dried product is further sieved through a 100-mesh sieve.

[0017] As a further improvement of the present application, in step S4, the N-methyl pyrrolidone solution of the polyvinylidene fluoride is prepared by dissolving 0.5-1.5g of polyvinylidene fluoride in 10-20ml of N-methyl pyrrolidone. In the liquid, the concentration of polyvinylidene fluoride is 1 g / L-10 g / L. Figure 1

[0018] As a further improvement of the present application, in step S4, the mass ratio of the catalyst Fe-NKBC to polyvinylidene fluoride is 3:1.

[0019] As a further improvement of the present application in step S4, the amount of the catalyst Fe-NKBC in the Fe-based biochar single-atom catalytic film SAFe@GF is 0.01-0.03g per piece of film.

[0020] As a further improvement of the present application, in step S1, the shrimp powder is obtained by washing, drying and grinding the shrimp skins.

[0021] As a further improvement of the present application, in step S1, the acid washing is performed for 2-6h using 1-3M hydrochloric acid.

[0022] The present application also discloses a Fe-based biochar single-atom catalytic film prepared by the preparation method of the Fe-based biochar single-atom catalytic film according to any one of the above.

[0023] The present application also discloses the application of the Fe-based biochar single-atom catalytic film as described above, which is used for catalyzing PDS to treat wastewater containing aniline substances.

[0024] The present application also discloses a wastewater treatment method for treating wastewater containing aniline substances by using the Fe-based biochar single-atom catalytic film and persulfate as described above.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] First, the technical scheme of the present application improves the activation efficiency of persulfate salt, and when used in combination with persulfate salt, not only can it efficiently catalyze and activate PDS to degrade aniline substances, but also solves the problem of difficult solid-liquid separation and recycling of traditional powder single-atom catalysts, showing good environmental adaptability and providing a new technical means for aniline wastewater treatment.

[0027] Second, the technical scheme of the present application, by constructing an N / O co-coordinated single-atom Fe catalyst and loading it on carbon felt, not only improves the activation efficiency of PDS (persulfate salt), but also maximizes the atomic utilization rate, minimizes metal dissolution, and optimizes pH adaptability, organically combining the high activity of single-atom catalysts with the high efficiency of membrane separation technology, and providing an innovative solution for industrial wastewater treatment. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 2 is the spherical aberration scanning transmission electron microscope and energy spectrum diagram of the embodiment 1 of the present application.

[0029] Figure 3 is the XPS full spectrum diagram and element content of the catalyst of the embodiment and the comparative example of the present application.

[0030] Figure 4 is the aniline removal rate in different reaction systems of the embodiment of the present application.

[0031] Figure 5 is the TOC removal rate in different reaction systems of the embodiment of the present application.

[0032] Figure 1 is the aniline removal rate in different water qualities of the embodiment of the present application. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present application are further described in detail below.

[0034] Embodiment 1

[0035] A preparation method of a Fe-based biochar single-atom catalytic membrane, comprising the following steps:

[0036] Preparation of biomass after acid washing: shrimp shells are washed several times with ethanol and water, dried, ground, sieved and dried for storage. Take an appropriate amount of shrimp powder as raw material, mix with an appropriate amount of 2M HCl for acid washing treatment for 2-6h, aiming to remove impurities and part of the minerals in the shrimp powder. After acid washing, the shrimp powder is washed thoroughly with deionized water to remove residual HCl, and blown to dryness.

[0037] Preparation of supermolecular organic framework: In order to reduce the preparation cost, improve the process safety and reduce the secondary pollution, the preparation process of the supermolecular organic framework is optimized. Specifically, melamine is dissolved in hot water at 80-95°C, and then an appropriate amount of ferrous sulfate is added after complete dissolution. An equal amount of cyanuric acid is dissolved in hot water at 80-95°C until it is completely dissolved. Slowly pour the cyanuric acid solution into the melamine solution and stir quickly for a period of time. Transfer the mixed solution to the upper chamber of the stirrer and stir at room temperature for 0.5-3h. Vacuum filter the mixed solution and dry the solid under vacuum to obtain Fe-SOFs. The amount of ferrous sulfate added is determined according to the mass ratio of Fe-SOFs to biomass in the next step and the mass ratio of Fe element in Fe-SOFs to biomass after acid washing. The amount of ferrous sulfate added satisfies that the iron element in Fe-SOFs accounts for 0.13% of the biomass after acid washing.

[0038] Preparation of Fe-NKBC catalyst: The acid-washed biomass, KOH and Fe-SOFs are added to a planetary ball mill in a mass ratio of 1:1.5:2, and ball-milled for 0.5-2h to ensure uniform mixing. Then, the ground mixture is placed in a calcination furnace and heated to 600-900°C at a heating rate of 5°C / min, and pyrolyzed for 1-3h. After the furnace naturally cools to room temperature, the remaining solid is ground and acid-washed for 0.5-2h, then washed with water and dried under vacuum to remove water. Finally, the dried product is passed through a 100-mesh sieve to obtain the target catalyst Fe-NKBC.

[0039] Preparation of Fe-based biochar single-atom catalytic membrane: The target catalyst prepared is mixed with polyvinylidene fluoride dissolved in N-methyl pyrrolidone under ultrasonic conditions, where the concentration of polyvinylidene fluoride is 5g / L, and the mass ratio of catalyst to polyvinylidene fluoride is 3:1. Then the obtained target catalyst slurry is uniformly added to the carbon felt, and vacuum dried to obtain the Fe-based biochar single-atom catalytic membrane SAFe@GF. In this embodiment, the amount of catalyst is 0.015g per piece of membrane.

[0040] Comparative example

[0041] Based on Example 1, this comparative example does not contain KOH, and the catalyst prepared is used as a control, named Fe-NBC as Comparative Example 1, and the catalytic membrane obtained is Fe-NBC@GF.

[0042] The original biochar BC is used as Comparative Example 2, and the catalytic membrane obtained is BC@GF.

[0043] The catalyst obtained in Example 1 is observed by spherical aberration scanning transmission electron microscopy, and the results are shown in Figure 2 The XPS full spectrum and the content of each element of Example 1 and the two comparative examples are shown in Figure 1As shown. From Figure 2 Mid-energy spectroscopy reveals that Fe, N, and O have all been successfully incorporated into the biochar framework, and the distribution of N and O shows a certain degree of correlation with Fe. Furthermore, aberration-corrected transmission electron microscopy confirms that Fe (the bright spot within the red circle) indeed exists as a single atom in SAFe-NKBC. Figure 3 It is evident that, compared to the Fe-NBC catalyst, which is undoped with KOH and doped only with Fe-SOFs, the Fe-NKBC obtained by co-doping with KOH and Fe-SOFs shows a significant increase in both N and O elements, with the O element increasing by nearly 13%. In previous studies, KOH has mostly been used to promote the formation of more porous structures or oxygen-containing functional groups (such as carboxyl and hydroxyl groups). However, in this embodiment, KOH mainly acts as an O precursor and simultaneously promotes the increase of N elements, which is significantly different from the role of KOH reported in existing inventions.

[0044] Ultimately, KOH and Fe-SOFs co-modify biochar, promoting N / O co-doping of the biochar support, thereby optimizing the electronic structure around Fe and aiming to improve the catalyst's catalytic performance for PDS.

[0045] Degradation experiments were conducted on the above-described embodiments and comparative examples.

[0046] Aniline was used as a representative substance of aniline pollutants. Aniline was dissolved in 50 mL of pure water to obtain a 20 mg / L aniline solution, and PDS was dissolved in water. A catalytic membrane was mounted on the reactor, and a peristaltic pump was started to initiate the reaction at a flow rate of 0.5-4 mL / min. At regular intervals, 1.0 mL of the reaction solution was taken, quenched with excess sodium thiosulfate, and passed through a 0.22 μm polytetrafluoroethylene membrane. The aniline concentration was then measured. The aniline and PDS solutions were mixed by the peristaltic pump and then flowed together through the SAFe@GF catalytic membrane for aniline degradation. In this experiment, a single-cycle filtration mode was used, resulting in a short contact time between the solution and the membrane. This necessitates exceptionally high catalytic performance from the catalyst to achieve efficient pollutant degradation. Furthermore, the PDS concentration was only 0.2 g / L, and the catalyst amount was 0.015 g / membrane.

[0047] Aniline removal rates in different reaction systems, such as Figure 4 As shown, the TOC removal rates in different reaction systems are as follows: Figure 5As shown in Fig. 6, the removal rate of aniline by SAFe@GF / PDS system was as high as 92%, and its catalytic effect could still be maintained well after 60 min of reaction, indicating that SAFe@GF had excellent and stable catalytic effect on PDS. This also provided data support for the successful modification of biochar by KOH and Fe-SOFs to promote N / O co-doped biochar to optimize the single-atom peripheral electronic structure. At the same time, compared with BC@GF / PDS, the removal rate of TOC by SAFe@GF / PDS was also significantly improved (increased by 51%), providing more reliable evidence for successful synergistic modification. It is worth noting that PDS has weaker oxidation ability than peroxymonosulfate (PMS). In the SAFe@GF / PDS process, the amount of catalyst and PDS is less, and the concentration of aniline treated is as high as 20 mg / L, which further illustrates the excellent catalytic degradation performance of the process.

[0048] In this embodiment, the obtained catalyst membrane is applied to actual water bodies, including river water, lake water and tap water, and the experimental results are as shown in Fig. 7. ​ As can be seen, the SAFe@GF / PDS system still maintains a very significant removal rate of aniline, and can still achieve a removal rate of aniline of nearly 80% after 60 min of reaction.

[0049] In summary, the SAFe@GF / PDS process not only can efficiently degrade aniline, but also solves the problem of difficult solid-liquid separation and recycling of traditional powder single-atom catalysts, showing good environmental adaptability and providing a new technical means for aniline wastewater treatment.

[0050] The above is a further detailed description of the present application in combination with specific preferred embodiments, and the specific implementation of the present application should not be limited to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be considered as falling within the protection scope of the present application.

Claims

1. A method for preparing Fe-based single-atom catalytic membrane of biochar, characterized in that, Comprising the following steps: Step S1, shrimp powder is pickled, then washed with water and dried to obtain a pickled biomass; Step S2, melamine is dissolved in hot water at 80-95℃, and ferrous sulfate is added to obtain solution A; Melamine is dissolved in hot water at 80-95℃ to obtain solution B; solution B is added to solution A, stirred for 0.5-3h, vacuum filtered, and the filtered solid is vacuum dried to obtain Fe-SOFs; Step S3, the pickled biomass, KOH and Fe-SOFs are mixed and ball milled for 0.5-2h to obtain a mixture, wherein the mass ratio of the pickled biomass, KOH and Fe-SOFs is 1:1-2:1.5-2.5, and the Fe element of Fe-SOFs accounts for 0.1-0.15% of the mass of the pickled biomass; the mixture is heated to 600-900℃ and pyrolyzed for 1-3h, then cooled to room temperature, ground, pickled for 0.5-2h, washed with water and dried to obtain a catalyst Fe-NKBC; Step S4, the catalyst Fe-NKBC is added to a polyvinylidene fluoride N-methyl pyrrolidone solution, wherein the mass ratio of the catalyst Fe-NKBC to polyvinylidene fluoride is 2-4:1, mixed uniformly, and dropped onto a carbon felt and vacuum dried to obtain a Fe-based biochar single-atom catalytic film SAFe@GF.

2. The method for preparing the Fe-based biochar single-atom catalytic membrane according to claim 1, characterized in that: In step S2, the ratio of the amount of substance of melamine in solution A to the amount of substance of cyanuric acid in solution B is 0.9-1.1:

1.

3. The method for preparing the Fe-based biochar single-atom catalytic membrane according to claim 1, characterized in that: In step S3, the mass ratio of the pickled biomass, KOH and Fe-SOFs is 1:1.5:2, and the Fe element of Fe-SOFs accounts for 0.13% of the mass of the biomass; the heating rate is 2-10℃ / min.

4. The method for preparing the Fe-based biochar single-atom catalytic membrane according to claim 3, characterized in that: In step S3, after washing and drying, the dried product is also sieved through a 100 mesh sieve.

5. The method of claim 1, wherein: In step S4, in the polyvinylidene fluoride N-methyl pyrrolidone solution, the concentration of polyvinylidene fluoride is 1g / L-10g / L; the mass ratio of the catalyst Fe-NKBC to polyvinylidene fluoride is 3:

1.

6. The method of claim 1-5, wherein the method comprises: In step S1, shrimp powder is obtained by washing, drying and grinding shrimp skins; the pickling is carried out with 1-3M hydrochloric acid for 2-6h.

7. The method for preparing the Fe-based biochar single-atom catalytic membrane according to claim 6, characterized in that: In step S4, the amount of catalyst Fe-NKBC in the Fe-based biochar single-atom catalytic film SAFe@GF is 0.01-0.03g per piece of film.

8. A Fe-based biocarbon monatomic catalytic membrane, characterized in that: Prepared by the method of any one of claims 1-7.

9. Use of the Fe-based biocarbon monatomic catalytic membrane according to claim 8, characterized by the fact that: Used for catalyzing PDS to treat wastewater containing aniline pollutants.

10. A method for treating wastewater containing aniline-type contaminants, characterized by: The Fe-based biochar single-atom catalytic film and persulfate of claim 8 are used to treat wastewater.

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