Fluorine-doped carbon material and its use in removing antibiotics

Abstract

The application 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. A preparation method of the fluorine-doped carbon material comprises the following steps: (1) mixing and grinding polytetrafluoroethylene powder and chitosan powder to obtain a polytetrafluoroethylene & chitosan mixture; (2) performing calcination treatment on the mixture under an inert atmosphere to obtain a calcined carbon material; and (3) washing and drying the calcined carbon material to obtain the fluorine-doped carbon material. An application method of the fluorine-doped carbon material in removal of antibiotics is as follows: adding the fluorine-doped carbon material and a peroxymonosulfate into a solution containing antibiotic pollutants to perform reaction, so as to obtain a solution in which antibiotic pollutants are removed. The preparation method of the fluorine-doped carbon material is simple, green, safe and low in cost. The fluorine-doped carbon material can generate singlet oxygen through a non-radical route, so that efficient degradation of antibiotic pollutants can be realized, and chemical residues after water body treatment can be effectively reduced.

Description

TECHNICAL FIELD

[0001] The application 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. BACKGROUND

[0002] Antibiotics, as a typical emerging organic pollutant, have been widely concerned in the world. Antibiotics play an important role in the treatment of human diseases and livestock and aquaculture, but the abuse of antibiotics makes them be discharged into water environment. Glycopeptide pollutants represented by vancomycin have complex structure and stable properties, and the antibiotics entering the water environment are difficult to be removed by the self-purification of water bodies, and promote the formation or enhancement of drug resistance in organisms through the coexistence accumulation effect, and even induce the generation of resistance genes. For human beings, long-term contact with vancomycin may cause serious consequences, such as shock, allergic 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 are imminent.

[0003] The persulfate-based advanced oxidation technology is a new wastewater treatment method. Among many advanced oxidation methods, this technology has the advantages of simple reaction equipment, wide application range, fast reaction speed, no secondary pollution, etc., and shows broad application prospects in the treatment of refractory organic wastewater. The activation of persulfate involves free radical and non-radical pathways, and the non-radical pathway has the advantages of strong specificity for pollutants, good anti-interference for common free radical quenchers and wide pH application range, but the activation pathway of the non-radical pathway still has uncertainty. With the development of science and technology, some studies have shown that heteroatom doping can control the electronic structure in the carbon skeleton and the surface chemical properties to promote the activation pathway to change from free radical to non-radical, for example: nitrogen doping into the pi-conjugated carbon network changes the free radical persulfate activation into a non-radical process dominated by electron transfer, but the nitrogen doping strategy to construct 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

[0004] In view of the defects and shortcomings of the prior art, the primary purpose of the present application is to provide a preparation method of fluorine-doped carbon material.

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

[0006] Still another purpose of the present application is to provide the application of the above fluorine-doped carbon material in the removal of antibiotics.

[0007] The application aims to realize the technical scheme as follows.

[0008] A preparation method of 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) baking the mixture obtained in step (1) under an inert atmosphere to obtain a baked carbon material;

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

[0012] Further, 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 <1 μm, and the particle size of the chitosan powder is 100-200 μm.

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

[0014] Further, the baking temperature in step (2) is 800℃, and the baking time is 1-4 h.

[0015] Further, the heating rate of the baking process in step (2) is 5℃ / min.

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

[0017] Further, the washing in step (3) means washing alternately with ethanol and water.

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

[0019] The fluorine-doped carbon material is used for removing antibiotics.

[0020] Further, the application method is as follows: fluorine-doped carbon material and peroxymonosulfate (PMS) are added to a solution containing antibiotic pollutants to react, and a solution with removed antibiotic pollutants is obtained.

[0021] In the above application method, the antibiotic pollutants are vancomycin; and the concentration of the antibiotic pollutants is 0-20 ppm.

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

[0023] In the application method, the fluorine-doped carbon material is used in an amount of 0.1-0.3 g / L; and the persulfate salt is used in an amount of 0.2-1.6 mM, preferably 0.4 mM.

[0024] In the application method, the reaction is carried out at a conventional room temperature and in an air atmosphere, and the solution containing the antibiotic contaminant has a pH of 3-11.

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

[0026] (1) In the conventional technology, the method for preparing the fluorine-doped carbon material usually uses toxic fluorine gas (F2), which is time-consuming and dangerous, and the plasma dissociation synthesis using CF4 as a fluorine precursor is not economical due to high cost. The fluorine-doped carbon material provided by the application is prepared by a high-temperature calcination method, so that a small amount of fluorine is loaded in the carbon material, thereby improving the activation efficiency of the material on the persulfate salt and selectively generating singlet oxygen to achieve efficient removal of the contaminant. The problems of high danger and high cost in the conventional synthesis process are solved, and the problem of unclear non-radical pathway in the persulfate salt advanced oxidation technology is also solved.

[0027] (2) The application uses commercial chitosan and polytetrafluoroethylene as raw materials, which are low in cost, and the synthesis method is simple, green and safe, and low in cost compared with the fluorine gas synthesis method and the plasma dissociation synthesis method. The carbon-based catalyst synthesized by the one-step calcination method simultaneously solves the problems of low activation efficiency of the persulfate salt and unclear non-radical pathway.

[0028] (3) The fluorine-doped carbon material of the application can selectively generate non-radical singlet oxygen in the activation process of the persulfate salt, and has better removal effect on the electron-rich organic contaminant such as antibiotic, can completely degrade the contaminant at a low concentration of 0.4 mM, effectively reduces the chemical residues after water treatment, and is more in line with the green environmental protection concept. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The XRD graph of the carbon material containing different F doping amounts prepared in Example 1 of the application.

[0030] Figure 2 The Raman graph of the carbon material containing different F doping amounts prepared in Example 1 of the application.

[0031] Figure 3 The X-ray photoelectron spectroscopy graph of CF-0 and CF-0.5 prepared in Example 1 of the application.

[0032] Figure 4 The transmission electron microscope graph and EDS mapping graph of CF-0.5 prepared in Example 1 of the application.

[0033] Figure 5 The CF-0, CF-0.25, CF-0.5 and CF-1 prepared in Example 1 of the present application were compared in terms of removal of vancomycin at room temperature.

[0034] Figure 6 The active species in the process of degrading vancomycin by CF-0.5 prepared in Example 1 of the present application were identified. DETAILED DESCRIPTION

[0035] The present application will be further described in conjunction with the examples and the accompanying drawings, but the embodiments of the present application are not limited thereto.

[0036] In the following examples, the concentration of vancomycin in the solution was measured by high performance liquid chromatography (HPLC, Thermo) at a detection wavelength of 280 nm, using a 5.0 μm C18 chromatographic column (4.6 x 150 mm). The mobile phase A contained 0.2% triethylamine buffer, acetonitrile and tetrahydrofuran at a volume ratio of 93.5:5.5:1; the mobile phase B contained 0.2% triethylamine buffer, acetonitrile and tetrahydrofuran at 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, comprising the following preparation steps:

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

[0040] (2) The polytetrafluoroethylene & chitosan mixtures were placed in a tube furnace and calcined at 800°C for 120 min under an argon atmosphere at a temperature increase rate of 5°C / min to obtain calcined carbon materials.

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

[0042] Chitosan without doping polytetrafluoroethylene was used as a control sample for comparison, and the chitosan was placed in a tube furnace and calcined at 800°C for 120 min under an argon atmosphere at a temperature increase rate of 5°C / min to obtain a catalyst control sample, which was named as CF-0.

[0043] Figure 1 XRD patterns of CF-0, CF-0.25, CF-0.5 and CF-1 catalysts prepared in this example confirmed the defect structure of the catalysts. All the catalysts showed two diffraction peaks centered at 24° and 44°, corresponding to the (002) and (100) planes of amorphous and crystalline carbon, respectively, indicating that fluorine doping did not change the crystal structure of the carbon material, and that there was both graphite carbon and amorphous carbon in all the catalyst materials.

[0044] Figure 2 Raman spectra of CF-0, CF-0.25, CF-0.5 and CF-1 catalysts prepared in this example. In the Raman spectrum, the D band at 1350 cm -1 and the G band at 1580 cm -1 indicate disordered carbon and graphitized carbon, respectively. The intensity ratio of the D band to the G band (I D / I G ) is generally used to quantify the defect degree of carbon materials. CF-0, CF-0.25, CF-0.5 and CF-1 were 1.07, 1.11, 1.12 and 1.21, respectively, indicating that fluorine-doped carbon improved the defect degree of the material.

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

[0046] Figure 4 Transmission electron micrographs and mapping images of CF-0.5 prepared in this example. The TEM image shows 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. From the Figure 4 -energy dispersive spectroscopy of CF-0.5, it can be seen that C, N, O and F elements are uniformly distributed on the surface of the carbon material.

[0047] Example 2

[0048] The application of fluorine-doped carbon material in removing antibiotics is as follows:

[0049] (1) 1.0 g of vancomycin was weighed and dissolved in 1000 mL of ultrapure water to prepare a 1000 ppm vancomycin solution.

[0050] (2) 0.2459 g of potassium peroxodisulfate (calculated by molecular weight 307.38) was dissolved in 10 mL of ultrapure water to prepare an 80 mM PMS solution.

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

[0052] The experimental results are shown in Table 1. Figure 5 As shown in Table 1, the results show that the CF-0 / PMS system has weak degradation effect on vancomycin, and the degradation effect is significantly improved with the doping of F; among them, the CF-0.5 / PMS system has the best degradation effect.

[0053] Example 3

[0054] Application of fluorine-doped carbon material CF-0.5 in removing antibiotics, and the reaction active species of CF-0.5 catalyst are explored, and the specific steps are as follows:

[0055] Take 1 mL of vancomycin solution in Example 2 and add 49 mL of ultrapure water to prepare a 20 ppm vancomycin solution. Then, add 0.01 g of CF-0.5 catalyst obtained in Example 1 to the prepared vancomycin solution, add 100 mM of methanol, t-butyl alcohol, furfuryl alcohol, benzoic acid and p-benzoquinone as reaction inhibitors, respectively, and finally add 0.25 mL of PMS solution in Example 2 to start the reaction. At specific time points, take out 1 mL of the reaction solution, filter it using a 0.22 μm organic filter membrane, mix it evenly with 50 μL of sodium thiosulfate, and then test it using high-performance liquid chromatography.

[0056] The experimental results are shown in Table 2. Figure 6 As shown in Table 2, the results show that when furfuryl alcohol is added, the reaction is basically completely inhibited, and when p-benzoquinone is added, there is also a certain inhibitory effect. It is shown that superoxide radicals and singlet oxygen are the main active species, and superoxide radicals cannot directly oxidize and degrade pollutants, and are usually precursors of singlet oxygen. Therefore, it is judged that the main active species is non-radical singlet oxygen. The subsequent EPR test further confirms this point.

[0057] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. The application of a fluorine-doped carbon material in the removal of antibiotics, characterized in that, The application method is as follows: adding fluorine-doped carbon material and persulfate to a solution containing antibiotic contaminants and reacting them to obtain a solution that removes antibiotic contaminants; The fluorine-doped carbon material was prepared by the following method: (1) Mix and grind polytetrafluoroethylene powder and chitosan powder to obtain a polytetrafluoroethylene & chitosan mixture; (2) The mixture obtained in step (1) is calcined under an inert atmosphere to obtain calcined carbon material; (3) The calcined carbon material obtained in step (2) is washed and dried to obtain fluorine-doped carbon material.

2. The application of a fluorine-doped carbon material according to claim 1 in the removal of antibiotics, characterized in that, The particle size of the polytetrafluoroethylene powder in step (1) is <1μm, and the particle size of the chitosan powder is 100~200μm.

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

1.

4. The application of a fluorine-doped carbon material according to claim 1 in the removal of antibiotics, characterized in that, The calcination temperature in step (2) is 800℃ and the time is 1~4h; the heating rate of the calcination is 5℃ / min.

5. The application of a fluorine-doped carbon material according to claim 1 in the removal of antibiotics, characterized in that, The inert atmosphere mentioned in step (2) is an argon atmosphere; the washing mentioned in step (3) refers to rinsing with ethanol and water alternately.

6. The application of a fluorine-doped carbon material according to claim 1 in the removal of antibiotics, characterized in that, The antibiotic contaminant is vancomycin; the concentration of the antibiotic contaminant is 0-20 ppm; the persulfate is potassium persulfate.

7. The application of a fluorine-doped carbon material according to claim 1 in the removal of antibiotics, characterized in that, The amount of fluorine-doped carbon material used is 0.1~0.3 g / L; the amount of persulfate used is 0.2~1.6 mM.

8. The application of a fluorine-doped carbon material according to claim 1 in the removal of antibiotics, characterized in that, The reaction conditions are normal room temperature and air atmosphere, and the pH of the solution containing antibiotic contaminants is 3-11.

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