Fluorine-doped carbon material and application thereof in removal of antibiotics

Abstract

The invention belongs to the technical field of catalytic materials and organic pollutant treatment, and particularly relates to a fluorine-doped carbon material and application thereof in removal of antibiotics. The preparation method of the fluorine-doped carbon material comprises the following steps: (1) mixing and grinding polytetrafluoroethylene powder and chitosan powder to obtain polytetrafluoroethylene amp; a chitosan mixture; (2) roasting the mixture in an inert atmosphere to obtain a roasted carbon material; and (3) washing and drying the roasted carbon material to obtain the fluorine-doped carbon material. The application method of the fluorine-doped carbon material in removal of antibiotics comprises the following steps: adding the fluorine-doped carbon material and peroxymonosulfate into a solution containing antibiotic pollutants for reaction to obtain the solution with the antibiotic pollutants removed. The preparation method of the fluorine-doped carbon material is simple, green, safe and low in cost. Singlet oxygen can be generated through a non-free radical way, so that efficient degradation of antibiotic pollutants is realized, and chemical residues after water treatment are effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic materials and organic pollutant treatment, and specifically relates to a fluorine-doped carbon material and an application thereof in removing antibiotics. Background Art

[0002] As a typical emerging organic pollutant, antibiotics have attracted widespread attention worldwide. Antibiotics play an important role in the treatment of human diseases, animal husbandry, and aquaculture, but the abuse of antibiotics has caused them to be discharged into the water environment in large quantities. Glycopeptide pollutants represented by vancomycin have complex structures and stable properties. Antibiotics that enter the water environment are difficult to be removed by the self-purification of the water body, and the coexistence cumulative effect promotes the formation or enhancement of drug resistance in organisms, and even induces the production of resistance genes. For humans, long-term exposure to vancomycin may lead to serious consequences, such as shock, allergic-like symptoms, kidney toxicity, blood system toxicity, skin and mucous membrane damage, brain nerve damage, liver function damage, etc. Therefore, the treatment and removal of vancomycin in wastewater is imminent.

[0003] Advanced oxidation technology based on permonosulfate is an emerging wastewater treatment method. Among the many advanced oxidation methods, this technology has the advantages of simple reaction equipment, wide application range, fast reaction speed, and no secondary pollution, and shows broad application prospects in the treatment of refractory organic wastewater. The activation of permonosulfate involves free radical and non-radical pathways, among which the non-radical pathway has the advantages of strong specific selectivity for pollutants, good anti-interference to common free radical quenchers, and a wide pH range, but the activation pathway of the non-radical pathway is still uncertain. With the development of science and technology, some studies have shown that heteroatom doping can promote the transformation of the activation pathway from free radical to non-radical by controlling the electronic structure and surface chemical properties in the carbon skeleton. For example, nitrogen doping into the π-conjugated carbon network transforms the free radical persulfate activation into a non-radical process dominated by electron transfer, but the nitrogen doping strategy for constructing a non-radical oxidation system still has randomness and uncertainty. Therefore, more efforts should be made to develop non-radical reaction targeted carbon catalysts. Summary of the invention

[0004] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing fluorine-doped carbon material.

[0005] Another object of the present invention is to provide a fluorine-doped carbon material prepared by the above method.

[0006] Another object of the present invention is to provide the use of the above-mentioned fluorine-doped carbon material activated to generate non-free radicals in the removal of antibiotics.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A method for preparing a fluorine-doped carbon material comprises the following steps:

[0009] (1) mixing and grinding polytetrafluoroethylene powder and chitosan powder to obtain a polytetrafluoroethylene & chitosan mixture;

[0010] (2) calcining the mixture obtained in step (1) under an inert atmosphere to obtain a calcined carbon material;

[0011] (3) Washing and drying the calcined carbon material obtained in step (2) to obtain a fluorine-doped carbon material.

[0012] Furthermore, the polytetrafluoroethylene powder and chitosan powder used in step (1) are commercial polytetrafluoroethylene powder and commercial chitosan powder; the particle size of the polytetrafluoroethylene powder is less than 1 μm, and the particle size of the chitosan powder is 100-200 μm.

[0013] Furthermore, in step (1), the mass ratio of chitosan powder to polytetrafluoroethylene powder is 16:1 to 4:1, preferably 8:1.

[0014] Furthermore, the calcination temperature in step (2) is 800° C. and the calcination time is 1 to 4 hours.

[0015] Furthermore, the heating rate of the calcination treatment in step (2) is 5°C / min.

[0016] Furthermore, the inert atmosphere in step (2) is an argon atmosphere.

[0017] Furthermore, the washing in step (3) refers to rinsing alternately with ethanol and water.

[0018] A fluorine-doped carbon material is prepared by the above method.

[0019] Application of the above fluorine-doped carbon material in removing antibiotics.

[0020] Furthermore, the application method is: adding fluorine-doped carbon material and peroxymonosulfate (PMS) to a solution containing antibiotic pollutants to react and obtain a solution for removing antibiotic pollutants.

[0021] In the above application method, the antibiotic pollutant is vancomycin; the concentration of the antibiotic pollutant is 0 to 20 ppm.

[0022] In the above application method, the peroxymonosulfate is potassium hydrogen persulfate.

[0023] In the above application method, the amount of the fluorine-doped carbon material is 0.1-0.3 g / L; the amount of the peroxymonosulfate is 0.2-1.6 mM, preferably 0.4 mM.

[0024] In the above application method, the reaction conditions are normal room temperature and air atmosphere, and the pH of the solution containing antibiotic pollutants is 3-11.

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

[0026] (1) In conventional techniques, methods for preparing fluorine-doped carbon materials usually use toxic fluorine gas (F2), which is time-consuming and dangerous, while plasma dissociation synthesis using CF4 as a fluorine precursor is expensive and uneconomical. The fluorine-doped carbon material provided by the present invention uses a high-temperature roasting method to load trace amounts of fluorine in the carbon material, thereby improving the activation efficiency of the material for persulfate and selectively generating singlet oxygen to achieve efficient removal of pollutants. This solves the problems of high risk and expensive process in the traditional synthesis process, and at the same time solves the problem of unclear non-radical pathways in the persulfate advanced oxidation technology.

[0027] (2) The present invention uses commercial chitosan and polytetrafluoroethylene as raw materials, the material price is low, the synthesis method is simple, and it is greener, safer, and has lower cost than the fluorine gas synthesis method and the plasma dissociation synthesis method. The carbon-based catalyst synthesized by the one-step calcination method solves the problems of low persulfate activation efficiency and unclear non-radical pathway.

[0028] (3) The fluorine-doped carbon material of the present invention can selectively produce non-radical singlet oxygen during the peroxymonosulfate activation process, and has a better removal effect on electron-rich organic pollutants such as antibiotics. It can completely degrade pollutants at a low concentration of 0.4 mM, effectively reducing chemical residues after water treatment, which is more in line with the concept of green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the XRD diagram of the carbon material containing different F doping amounts prepared in Example 1 of the present invention.

[0030] Figure 2 This is the Raman image of the carbon material containing different F doping amounts prepared in Example 1 of the present invention.

[0031] Figure 3 This is the X-ray photoelectron spectrum of CF-0 and CF-0.5 prepared in Example 1 of the present invention.

[0032] Figure 4 The transmission electron microscope image and EDS mapping image of CF-0.5 prepared in Example 1 of the present invention are shown.

[0033] Figure 5 This is a comparison chart of the removal of vancomycin by CF-0, CF-0.25, CF-0.5 and CF-1 prepared in Example 1 of the present invention at room temperature.

[0034] Figure 6 This is a diagram showing the identification of active species during the degradation of vancomycin by CF-0.5 prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0036] In the following examples, high performance liquid chromatography (HPLC, Thermo) was used to measure the concentration of vancomycin in the solution, with a detection wavelength of 280 nm and a 5.0 μm C18 chromatographic column (4.6×150 mm). Mobile phase A contained 0.2% triethylamine buffer, acetonitrile and tetrahydrofuran in a volume ratio of 93.5:5.5:1; mobile phase B contained 0.2% triethylamine buffer, acetonitrile and tetrahydrofuran in a volume ratio of 70:29:1; the flow rate was fixed at 2.0 mL / min, the injection volume was 20 μL, and the column temperature was set at 30°C. Under the above test conditions, the retention time of vancomycin was about 6 min.

[0037] Example 1

[0038] A method for preparing a fluorine-doped carbon material comprises the following steps:

[0039] (1) 0.25 g, 0.5 g and 1 g of polytetrafluoroethylene powder (commercially purchased, particle size <1 μm) and 4 g of chitosan powder (commercially purchased, particle size 100-200 μm) were mixed and ground thoroughly to obtain a polytetrafluoroethylene & chitosan mixture;

[0040] (2) The obtained polytetrafluoroethylene and chitosan mixture was placed in a tubular furnace, heated to 800°C at a rate of 5°C / min under an argon atmosphere, and calcined for 120 min to obtain a calcined carbon material.

[0041] (3) The calcined carbon materials were washed three times with 50 mL of ultrapure water and 50 mL of ethanol alternately, filtered, and then dried in a vacuum drying oven at 65 °C for 720 min. The carbon materials were named CF-0.25, CF-0.5, and CF-1 according to the different fluorine doping amounts.

[0042] Chitosan without polytetrafluoroethylene was used as an experimental control sample. The chitosan was placed in a tubular furnace and calcined at 800°C at a rate of 5°C / min for 120 min in an argon atmosphere. The obtained catalyst control sample was named CF-0.

[0043] Figure 1 The XRD patterns of the catalysts CF-0, CF-0.25, CF-0.5 and CF-1 prepared in this example confirm the defective structures. All catalysts show two diffraction peaks centered at 24° and 44°, corresponding to the (002) and (100) planes of amorphous carbon and crystalline carbon, respectively. This result indicates that fluorine doping does not change the crystal structure of the carbon material, and graphitic carbon and amorphous carbon are present in all catalyst materials.

[0044] Figure 2 : is the Raman spectrum of the CF-0, CF-0.25, CF-0.5 and CF-1 catalysts prepared in this example. In the Raman spectrum, 1350cm -1 D band at 1580cm -1 The G bands at the D band and the G band at the G band refer to disordered carbon and graphitized carbon, respectively. D / I G ) is used to quantify the degree of defects in carbonaceous materials. The values ​​of CF-0, CF-0.25, CF-0.5 and CF-1 are 1.07, 1.11, 1.12 and 1.21 respectively, indicating that fluorine-doped carbon increases the degree of defects in the material.

[0045] Figure 3 CF-0 and CF-0.5 prepared in this example are X-ray photoelectron spectra; the scanning of the fluorine peak confirms the doping of fluorine element.

[0046] Figure 4 The TEM image and its mapping diagram of CF-0.5 prepared in this example show clear lattice fringes with an interlayer spacing of 0.33 nm, which belongs to the (002) plane of graphite, indicating the graphite structure of CF-0.5. Figure 4 From the energy dispersion spectrum of CF-0.5 in -f, it can be seen that the four elements C, N, O, and F are evenly distributed on the surface of the carbon material.

[0047] Example 2

[0048] The application of fluorine-doped carbon materials in the removal of antibiotics, the specific steps are as follows:

[0049] (1) Weigh 1.0 g of vancomycin and dissolve it in 1000 mL of ultrapure water to prepare a 1000 ppm vancomycin solution.

[0050] (2) Weigh 0.2459 g of potassium persulfate (molecular weight 307.38) and dissolve it in 10 mL of ultrapure water to prepare an 80 mM PMS solution.

[0051] (3) 1 mL of vancomycin solution was added to 49 mL of ultrapure water to prepare a 20 ppm vancomycin solution with a pH of 7. Then, 0.01 g of the fluorine-doped carbon material catalyst obtained in Example 1 was added to the prepared vancomycin solution, and 0.25 mL of PMS solution was added to start the reaction. The reaction was carried out under normal room temperature and air conditions. 1 mL of the reaction solution was taken out at a specific time point, filtered using a 0.22 μm organic filter membrane, and then mixed evenly with 50 μL of sodium thiosulfate and tested using high performance liquid chromatography.

[0052] The experimental results are as follows Figure 5 As shown, the results show that the degradation effect of CF-0 / PMS system on vancomycin is very weak, and the degradation effect is significantly improved with the doping of F; among them, the degradation effect of CF-0.5 / PMS system is the best.

[0053] Example 3

[0054] The application of fluorine-doped carbon material CF-0.5 in the removal of antibiotics and the exploration of the reactive species of CF-0.5 catalyst are as follows:

[0055] 1 mL of the vancomycin solution in Example 2 was added to 49 mL of ultrapure water to prepare a 20 ppm vancomycin solution, and then 0.01 g of the CF-0.5 catalyst obtained in Example 1 was added to the prepared vancomycin solution, 100 mM methanol, tert-butyl alcohol, furfuryl alcohol, benzoic acid and p-benzoquinone were added as reaction inhibitors, and finally 0.25 mL of the PMS solution in Example 2 was added to start the reaction. 1 mL of the reaction solution was taken out at a specific time point, filtered using a 0.22 μm organic filter membrane, and then mixed evenly with 50 μL of sodium thiosulfate and tested using high performance liquid chromatography.

[0056] The experimental results are as follows Figure 6 As shown, the results show that when furfuryl alcohol is added, the reaction is basically completely inhibited, and there is also a certain inhibitory effect after adding benzoquinone. It shows that superoxide radicals and singlet oxygen are the main active species, and superoxide radicals cannot directly oxidize and degrade pollutants. It usually acts as a precursor of singlet oxygen. Therefore, it is judged that the main active species is non-radical singlet oxygen; the subsequent EPR test further confirmed this.

[0057] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a fluorine-doped carbon material, characterized in that: The method comprises the following preparation steps: (1) mixing and grinding polytetrafluoroethylene powder and chitosan powder to obtain a polytetrafluoroethylene & chitosan mixture; (2) calcining the mixture obtained in step (1) under an inert atmosphere to obtain a calcined carbon material; (3) Washing and drying the calcined carbon material obtained in step (2) to obtain a fluorine-doped carbon material.

2. The method for preparing a fluorine-doped carbon material according to claim 1, characterized in that: The particle size of the polytetrafluoroethylene powder in step (1) is less than 1 μm, and the particle size of the chitosan powder is 100 to 200 μm.

3. The method for preparing a fluorine-doped carbon material according to claim 1, characterized in that: The mass ratio of chitosan powder to polytetrafluoroethylene powder in step (1) is 16:1 to 4:

1.

4. The method for preparing a fluorine-doped carbon material according to claim 1, characterized in that: The temperature of the calcination treatment in step (2) is 800°C, and the time is 1 to 4 hours; the heating rate of the calcination treatment is 5°C / min.

5. The method for preparing a fluorine-doped carbon material according to claim 1, characterized in that: The inert atmosphere in step (2) is an argon atmosphere; the washing in step (3) refers to washing with ethanol and water alternately.

6. A fluorine-doped carbon material, characterized in that: It is prepared by the method according to any one of claims 1 to 5.

7. Use of a fluorine-doped carbon material according to claim 6 in removing antibiotics, characterized in that: The application method is: adding fluorine-doped carbon material and peroxymonosulfate into a solution containing antibiotic pollutants to react, thereby obtaining a solution for removing antibiotic pollutants.

8. The use of a fluorine-doped carbon material in removing antibiotics according to claim 7, characterized in that: The antibiotic pollutant is vancomycin; the concentration of the antibiotic pollutant is 0-20 ppm; and the peroxymonosulfate is potassium hydrogen persulfate.

9. The use of a fluorine-doped carbon material in removing antibiotics according to claim 7, characterized in that: The amount of the fluorine-doped carbon material used is 0.1-0.3 g / L; the amount of the peroxymonosulfate used is 0.2-1.6 mM.

10. The use of a fluorine-doped carbon material in removing antibiotics according to claim 7, characterized in that: The reaction conditions are normal room temperature and air atmosphere, and the pH of the solution containing antibiotic pollutants is 3-11.

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