FeCo co-loaded C3N4 material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of environmental protection and sewage treatment materials, and discloses a FeCo co-loaded C3N4 material as well as a preparation method and application thereof. The method comprises the following steps: (1) adding an iron salt and a cobalt salt into a urea aqueous solution for a first contact reaction to obtain a mixture I; (2) at 178-182 DEG C, mixing the mixture I with a melamine solution to carry out a second contact reaction, and separating and drying to obtain a mixture II; and (3) carrying out heat treatment on the mixture II to obtain the FeCo co-loaded C3N4 material. The method provided by the invention not only has the characteristics of simple preparation process and low cost, but also the obtained FeCo co-loaded C3N4 material can realize adsorption and degradation of antibiotic resistance genes at the same time, and has a very obvious effect.

Description

Technical Field

[0001] This invention relates to the field of environmental protection and wastewater treatment materials technology, specifically to an FeCo co-supported C3N4 material, its preparation method, and its application. Background Technology

[0002] With the widespread use of tetracycline antibiotics in medicine, animal husbandry, and aquaculture, their continuous accumulation in environmental media has posed a serious ecological threat. Studies indicate that tens of thousands of tons of antibiotics are released into the natural environment globally each year. Tetracyclines, due to their high chemical stability and poor biodegradability, can leave residues in water and soil at concentrations ranging from ng / L to mg / L. Even more seriously, tetracyclines can induce mutations in microbial genes, promoting the formation of antibiotic resistance genes (ARGs). tetW , tetM These genetically modified organisms (AGGs) can transfer and spread in aquatic environments. They can spread between different bacterial species, forming "secondary pollution" with self-replicating capabilities. Even if the antibiotic itself is removed, ARGs can persist for a long time and induce the emergence of superbugs, posing a persistent risk to ecosystems and public health.

[0003] To address these emerging pollutants, adsorption / catalytic materials based on graphitic carbon nitride (g-C3N4) have attracted considerable attention in recent years. g-C3N4 possesses a unique conjugated π-electron structure, suitable band positions (approximately 2.7 eV), and good chemical stability, making it widely used in the photocatalytic degradation of organic pollutants. However, the removal efficiency of g-C3N4 alone for tetracyclines and ARGs is significantly limited, with two fundamental drawbacks: First, the material surface lacks specific functional groups (such as carboxyl and phosphate groups), resulting in low adsorption affinity for tetracycline molecules (Langmuir adsorption constant is typically <50 L / mol), making it difficult to achieve efficient enrichment of pollutants. Second, g-C3N4 alone has a weak ability to activate persulfates (such as permonosulfate PMS), and its conduction band electrons are insufficient to effectively excite the decomposition of PMS to generate sufficient reactive oxygen species (ROS, including ·OH, etc.). (etc.), resulting in low catalytic degradation efficiency of ARGs (under typical conditions) tetW Removal rate < 0.5 log).

[0004] To address the aforementioned issues, researchers have attempted to improve the performance of g-C3N4 through metal modification strategies. For example, single-metal loading (Fe or Co) can partially enhance the PMS activation ability—iron-based materials can be modified with Fe... 2+ / Fe 3+ Cyclic generation of ·OH (E o =2.8 V), cobalt-based materials through Co 2+ / Co3+ Cycle dominance Generate (E) o =2.6-3.1 V). However, such monometallic modified systems still have significant bottlenecks: firstly, the redox cycle kinetics are slow (e.g., Fe = 2.6-3.1 V). 3+ →Fe 2+ The reduction rate constant k < 0.1 min -1 First, the ROS production is insufficient and the reaction cycle is prolonged. Second, the functional mechanism is singular, relying on independent pathways of adsorption or catalysis, which cannot simultaneously achieve efficient enrichment and deep destruction of ARGs, especially for smaller (<1000 bp) and structurally stable gene fragments, the retention rate is less than 40%. Third, the active metal components are easily dissolved (Fe / Co dissolution rate >15% after 5 cycles), causing material structure collapse and long-term degradation.

[0005] Therefore, developing a bifunctional material that combines strong adsorption and capture capabilities with highly efficient catalytic oxidation activity to achieve efficient removal of ARGs through an adsorption-catalysis synergistic mechanism has become an urgent need in the field of environmental functional materials. In particular, it is necessary to overcome key technological bottlenecks such as the electronic synergistic regulation of bimetallic sites and the enhancement of the stability of active centers, in order to fundamentally block the environmental transmission pathways of antibiotic resistance genes. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of poor removal effect of tetracycline resistance genes, slow redox cycle kinetics, and single functional mechanism in the prior art using C3N4 materials.

[0007] To achieve the above objectives, a first aspect of the present invention provides a method for preparing FeCo-supported C3N4 materials, the method comprising the following steps: (1) Add iron salt and cobalt salt to urea aqueous solution to carry out the first contact reaction to obtain mixture I; (2) At 178-182℃, the mixture I was mixed with a melamine solution to carry out a second contact reaction, and after separation and drying, the mixture II was obtained; (3) Heat treatment is performed on the mixture II to obtain FeCo co-loaded C3N4 material.

[0008] The second aspect of the present invention provides FeCo co-supported C3N4 material prepared by the method described in the first aspect above.

[0009] The third aspect of this invention provides the application of the FeCo co-loaded C3N4 material described in the second aspect above in the treatment of wastewater containing antibiotic resistance genes.

[0010] The working principle of this invention includes: In this invention, on the one hand, Fe can bind to the phosphate bond site of antibiotic resistance genes, thereby... 3+ With ARGs phosphate groups (PO4) 3- Fe-OP coordination bonds are formed, thereby adsorbing antibiotic resistance genes; on the other hand, Fe and Co are atomically dispersed and co-loaded on a C3N4 vector, where Fe and Co sites on the vector surface activate persulfate, and Fe is present. 2+ / Fe 3+ Co 2+ / Co 3+ The cyclic mechanism involves the generation of strong oxidizing free radicals and non-free radicals, which disrupt the base structure of antibiotic resistance genes, thus degrading them. The efficient degradation of antibiotic resistance genes is achieved through the adsorption of Fe and the in-situ activation of persulfate by Fe and Co.

[0011] Compared with the prior art, the present invention has at least the following advantages: (1) The preparation method provided by the present invention is simple and low in cost, and the FeCo co-loaded C3N4 material obtained can achieve the purpose of efficiently treating antibiotic resistance genes; (2) This invention loads Fe into C3N4 to improve the material's adsorption efficiency for antibiotic resistance genes. Simultaneously, it utilizes the ability of Fe and Co to activate persulfate, enabling the bimetallic sites to synergistically degrade antibiotic resistance genes. (3) The FeCo co-loaded C3N4 material prepared in this invention has a very significant improvement effect on the degradation performance of antibiotic resistance genes. Specifically, for ~10... 10 copies / mL tetW After adding the loaded C3N4 material and potassium persulfate compound salt (PMS) to the solution for 30 min, the reaction was carried out. tetW The removal efficiencies were 6.12 log, 6.27 log, and 5.95 log; while under the same conditions, the C3N4 material showed better removal efficiency. tetW The removal efficiency is 0.2 log. Attached Figure Description

[0012] Figure 1 This is a graph showing the degradation effect of the loaded C3N4 material obtained in the comparative example of the present invention on antibiotic resistance genes in solution; Figure 2 This is a diagram showing the degradation effect of the loaded C3N4 material on antibiotic resistance genes in solution obtained in the preferred embodiments and comparative examples provided by the present invention. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] As mentioned above, the first aspect of the present invention provides a method for preparing FeCo co-supported C3N4 materials, the method comprising the following steps: (1) Add iron salt and cobalt salt to urea aqueous solution to carry out the first contact reaction to obtain mixture I; (2) At 178-182℃, the mixture I was mixed with a melamine solution to carry out a second contact reaction, and after separation and drying, the mixture II was obtained; (3) Heat treatment is performed on the mixture II to obtain FeCo co-loaded C3N4 material.

[0015] In a preferred embodiment, in step (1), the molar ratio of the total amount of iron salt and cobalt salt, the molar amount of urea in the urea aqueous solution, and the molar amount of melamine in the melamine solution is 1:440-460:150-170.

[0016] Preferably, in step (1), the concentration of urea in the urea aqueous solution is 16.60-20.60 wt%.

[0017] In a preferred embodiment, in step (1), the iron salt is FeCl3•6H2O and the cobalt salt is CoCl2•6H2O.

[0018] Preferably, in step (1), the Fe in the iron salt 3+ With Co in the cobalt salt 2+ The molar ratio of the two components is 1:1. Under this preferred condition, better degradation is achieved. tetW .

[0019] In a preferred embodiment, in step (1), the first contact reaction is carried out under ultrasonic conditions, with an ultrasonic power of 540W and a duration of 10-15min.

[0020] It should be noted that, in this invention, the urea aqueous solution refers to an aqueous solution of urea. The melamine solution refers to an aqueous solution of melamine.

[0021] Preferably, in step (2), the concentration of melamine in the melamine solution is 12.63-16.63 wt%.

[0022] According to a preferred embodiment, the method of the present invention further includes: in step (2), before carrying out the second contact reaction, the mixture I is first mixed with the melamine solution under stirring conditions at 22-26°C and a rotation speed of 400-500 rpm for 0.5-1.0 h, and then transferred to a reaction vessel for carrying out the second contact reaction at 178-182°C for 24.0-24.5 h. In this preferred embodiment, the FeCo reaction sites can be uniformly loaded on the C3N4 precursor, and the stability of the material structure can be maintained during pyrolysis, thereby facilitating the adsorption and binding of Fe and the target pollutant antibiotic resistance gene, adsorbing the antibiotic resistance gene onto the surface of the composite material, and then activating the persulfate through the Co and Fe sites to achieve efficient degradation of the antibiotic resistance gene.

[0023] More preferably, in step (2), the second contact reaction is carried out under stirring conditions at a speed of 400-500 rpm.

[0024] In a preferred embodiment, the method of the present invention further includes: in step (2), the separation step includes: allowing the system after the second contact reaction to cool naturally, washing the precipitate with deionized water, then centrifuging, and then washing the precipitate with anhydrous ethanol and ultrapure water in sequence to obtain intermediate I, and then applying the intermediate I to the drying.

[0025] In a preferred embodiment, the method of the present invention further includes: in step (2), the drying conditions at least satisfy: a temperature of 60-72°C and a time of 8-10h.

[0026] Preferably, in step (3), the heat treatment conditions must at least satisfy: temperature of 548-553℃ and time of 2.0-2.5h.

[0027] As previously stated, the second aspect of the present invention provides FeCo co-supported C3N4 material prepared by the method described in the first aspect above.

[0028] As previously stated, the third aspect of this invention provides the application of the FeCo co-loaded C3N4 material described in the second aspect above in the treatment of wastewater containing antibiotic resistance genes.

[0029] The present invention will be described in detail below through examples. Unless otherwise specified, the raw materials used are all commercially available products.

[0030] Iron salt: FeCl3•6H2O; Cobalt salt: CoCl2•6H2O.

[0031] Example 1 This embodiment illustrates that the method for preparing FeCo-supported C3N4 materials provided by the present invention is carried out according to the following steps: S1. Weigh 8g of urea and dissolve it in ultrapure water. Stir with a glass rod to dissolve the urea solution with a concentration of 18.60wt%. S2. Under ultrasonic conditions (power 540W), iron salt and 35 mg cobalt salt were added to a urea aqueous solution for a first contact reaction of 10 min to obtain mixture I; Fe in the iron salt 3+ Co in cobalt salts 2+ The molar ratio of the dosages is 1:1; S3. Weigh 6g of melamine and dissolve it in ultrapure water. Stir with a glass rod to dissolve the melamine to obtain a melamine solution with a concentration of 14.63wt%. S4. First, mix the mixture I with the melamine solution at 25°C and 450 rpm for 1 hour, then transfer it to a reaction vessel and carry out the second contact reaction at 180°C for 24.0 hours to obtain a precipitate. S5. After the system has cooled naturally, wash the precipitate obtained from the second contact reaction with deionized water, then centrifuge it, and then wash the precipitate with anhydrous ethanol and ultrapure water in sequence to obtain intermediate I. Then dry intermediate I under vacuum at 72°C for 8 hours to obtain mixture II. S6. Heat-treat the mixture II at 550°C for 2.0 h to obtain FeCo co-supported C3N4 material, named P1.

[0032] Example 2 This embodiment uses a method similar to that of Example 1, except that the weight of the cobalt salt is adjusted to 52 mg, and the amount of iron salt is changed so that the Fe content in the iron salt is... 3+ With Co in the cobalt salt 2+ The molar ratio of the dosages is 1:3; Finally, FeCo co-supported C3N4 material was obtained and named P2.

[0033] Example 3 This embodiment uses a method similar to that of Example 1, except that the weight of cobalt salt is adjusted to 18 mg, and the amount of iron salt is changed so that the Fe content in the iron salt is... 3+ With Co in the cobalt salt 2+ The molar ratio of the dosages is 3:1; Finally, FeCo co-supported C3N4 material was obtained and named P3.

[0034] Comparative Example 1 This comparative example was conducted using a method similar to that of Example 1, except that the weight of cobalt salt was adjusted to 18 mg and the weight of iron salt was 0 mg. Finally, a Co-supported C3N4 material was obtained and named DP1.

[0035] Comparative Example 2 This comparative example was conducted using a method similar to that of Example 1, except that the weight of cobalt salt was adjusted to 0 and the weight of iron salt was adjusted to 50 mg. Finally, Fe-supported C3N4 material was obtained and named DP2.

[0036] Comparative Example 3 This comparative example was conducted using a method similar to that of Example 1, except that the weight of cobalt salt was adjusted to 0 and the weight of iron salt was adjusted to 60 mg. Finally, Fe-supported C3N4 material was obtained and named DP3.

[0037] Comparative Example 4 This comparative example was conducted using a method similar to that of Example 1, except that the weight of cobalt salt was adjusted to 0 and the weight of iron salt was adjusted to 80 mg. Finally, Fe-supported C3N4 material was obtained and named DP4.

[0038] Comparative Example 5 This comparative example was conducted using a method similar to that of Example 1, except that the weight of cobalt salt was adjusted to 0 and the weight of iron salt was adjusted to 100 mg. Finally, Fe-supported C3N4 material was obtained and named DP5.

[0039] Comparative Example 6 This comparative example was conducted using a method similar to that of Example 1, except that the weight of cobalt salt was adjusted to 0 and the weight of iron salt was adjusted to 59 mg. Finally, Fe-supported C3N4 material was obtained and named DP6.

[0040] Test Example 1 The loaded C3N4 material obtained in the above examples was used to test the antibiotic resistance genes in aqueous solution. tetW Degradation and removal tests were conducted, specifically including: The concentration to be prepared is ~10 10 Antibiotic resistance gene copies / mL tetWTake 5 mL of antibiotic resistance gene solution and add it to 15 mL sterile centrifuge tubes. Add 2.5 mg of the loaded C3N4 material to each tube and stir in a shaker at room temperature. After 60 min, add 1 mM PMS. At certain time intervals, take 200 μL of the solution to centrifuge tubes, add Na2S2O3 quencher, and then determine the concentration of antibiotic resistance gene by real-time quantitative PCR. Record the time when the loaded C3N4 material is added as t=-60 min and the time when PMS is added as t=0 min.

[0041] The results are as follows Figure 1 and Figure 2 As shown, where, Figure 1 The diagrams show DP2, DP3, DP4, and DP5. tetW Removal efficiency; Figure 2 The diagram shows DP1, DP6, P1, P2, and P3. tetW Removal efficiency. As can be seen from the figure, the C3N4 material loaded only with Fe... tetW Ultimately, the removal efficiency is significantly lower than that of C3N4 material simultaneously loaded with Fe and Co.

[0042] The results above show that the method provided by this invention not only has the advantages of simple preparation process and low cost, but also the FeCo co-loaded C3N4 material obtained can simultaneously adsorb and degrade antibiotic resistance genes, and has a very obvious effect.

[0043] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing FeCo co-supported C3N4 materials, characterized in that, The method includes the following steps: (1) Add iron salt and cobalt salt to urea aqueous solution to carry out the first contact reaction to obtain mixture I; (2) At 178-182℃, the mixture I was mixed with a melamine solution to carry out a second contact reaction, and after separation and drying, the mixture II was obtained; (3) Heat treatment is performed on the mixture II to obtain FeCo co-loaded C3N4 material.

2. The method according to claim 1, characterized in that, In step (1), the total molar amount of the iron salt and the cobalt salt, the molar amount of urea in the urea aqueous solution, and the molar amount of melamine in the melamine solution are in the ratio of 1:440-460:150-170.

3. The method according to claim 1 or 2, characterized in that, In step (1), the iron salt is FeCl3•6H2O and the cobalt salt is CoCl2•6H2O.

4. The method according to claim 1 or 2, characterized in that, In step (1), the Fe in the iron salt 3+ With Co in the cobalt salt 2+ The molar ratio of the dosage is 1:1-3.

5. The method according to claim 1 or 2, characterized in that, In step (1), the first contact reaction is carried out under ultrasonic conditions, with an ultrasonic power of 540W and a duration of 10-15min.

6. The method according to claim 1 or 2, characterized in that, The method further includes: in step (2), before carrying out the second contact reaction, mixing the mixture I with the melamine solution at 22-26°C with a stirring speed of 400-500 rpm for 0.5-1.0 h, and then transferring it to a reaction vessel to carry out the second contact reaction at 178-182°C for 24.0-24.5 h.

7. The method according to claim 1 or 2, characterized in that, The method further includes: in step (2), the separation step includes: after the system after the second contact reaction is naturally cooled, the precipitate is washed with deionized water, then centrifuged, and then the precipitate is washed with anhydrous ethanol and ultrapure water in sequence to obtain intermediate I, and then the intermediate I is applied to the drying.

8. The method according to claim 1 or 2, characterized in that, In step (3), the heat treatment conditions must at least meet the following requirements: temperature of 548-553℃ and time of 2.0-2.5h.

9. The FeCo co-loaded C3N4 material prepared by the method according to any one of claims 1-8.

10. The application of the FeCo co-loaded C3N4 material according to claim 9 in the treatment of wastewater containing antibiotic resistance genes.

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