Monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material, preparation method and application thereof

Abstract

The application discloses a kind of single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material and preparation method and application thereof, single-atom nickel is uniformly dispersed on crystalline carbon nitride nanowire array.Its preparation method is: crystalline carbon nitride nanowire array is suspended in deionized water to obtain suspension;Nickel nitrate solution is added dropwise to the above suspension, and single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material is obtained after stirring and annealing.The single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material of the application has high crystallinity, realizes the minimization of defects in structure, inhibits electron hole recombination, expands the light absorption range, accelerates charge transfer and provides more active sites for catalytic reaction, vertical nanowire array structure has direct one-dimensional electron channel, can realize effective charge transport and shorten charge transport path, thereby improve the photocatalytic activity of catalyst, promote the photocatalytic degradation effect, and can be applied to the degradation of antibiotics in wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials and environmental protection, in particular to a single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, a preparation method thereof and an application thereof. BACKGROUND

[0002] In recent years, due to the increasingly prominent energy crisis and environmental pollution problems, the use of photocatalysts to degrade pollutants in the environment as an environmentally friendly and low-cost technology has received extensive attention. Photocatalytic technology can photolyze and mineralize pollutants into water and carbon dioxide, rather than concentrating pollutants and their by-products and then discharging them into the water environment again. Compared with traditional biological, physical and chemical methods, it has the advantages of simple operation, mild reaction conditions, strong purification capacity, low energy consumption and no secondary pollution, and is the preferred technology for deep treatment of wastewater. However, most catalysts face some practical problems, namely: (1) low utilization rate of sunlight, which can only be activated in a lower wavelength region. (2) High electron and hole recombination rate greatly reduces the photocatalytic efficiency. Research on new and efficient photocatalysts provides a wider space for the development of future photocatalytic technology.

[0003] As a new type of metal-free visible light driven photocatalyst, it has attracted much attention due to its attractive electronic band structure and excellent physicochemical stability. Carbon nitride has excellent physical and chemical properties, including a moderate band gap and good visible light response ability, making it a material with excellent visible light photocatalytic performance. Most carbon nitrides are derived from the thermal-induced polymerization of nitrogen-containing precursors to form amorphous structures with a large number of defects. Such defects will act as recombination centers for electron-hole pairs, thereby limiting the inherent photocatalytic activity of carbon nitride.

[0004] In order to better apply carbon nitride, researchers have conducted extensive research to overcome its shortcomings. Studies have found that introducing metal substances into the carbon nitride framework can improve the catalytic activity of carbon nitride. Metal substances can adjust the band gap structure, expand the light absorption range, accelerate charge transfer and provide more active sites for catalytic reactions. In particular, when the metal is loaded on the support surface in the form of isolated atoms to form single atoms, the exposure rate of single metal atoms can theoretically reach 100%. These unsaturated coordinated atoms have great activity, and each atom can serve as an active site, ensuring the extremely high catalytic performance of the material. Under the premise of equivalent catalytic performance, the single-atom catalytic system can greatly save material costs. However, single atoms are very easy to agglomerate during the preparation process, forming metal particles or metal clusters. In addition, the synthesis process of single-atom catalysts is often cumbersome, making it difficult to achieve large-scale application. The loading capacity of the currently synthesized metal single atoms is generally low, and the atom utilization efficiency is not high. Therefore, through a simple and easy-to-operate preparation method, the pyridinic nitrogen rich in the carbon nitride cavity and the coordination of more metal atoms are used to synthesize a high-load single-atom catalyst, obtaining a new type of single-atom-introduced crystalline carbon nitride with a larger specific surface area, stronger light absorption and faster charge transfer rate, and applying it in the water treatment process, which has great practical significance. Summary of the Invention

[0005] The present invention provides a single-atom nickel-modified crystalline carbon nitride nanowire array photocatalytic material, its preparation method, and application. By increasing the crystallinity of carbon nitride and minimizing structural defects, highly crystalline carbon nitride with reduced structural defects can significantly inhibit electron-hole recombination. Metallic nickel can modulate the band gap structure, expand the light absorption range, and accelerate charge transfer. The introduction of metallic nickel species into the carbon nitride framework can provide more active sites for catalytic reactions. The presence of electron-rich nitrogen sites in carbon nitride provides an ideal location for nickel atoms, thereby achieving uniformly dispersed single-atom nickel anchoring and effectively improving the catalytic activity of carbon nitride. The direct one-dimensional electron channel of the vertical nanowire array structure enables efficient charge transport and shortens the ion transport length, thereby significantly improving the overall photocatalytic performance of the photocatalyst. The preparation process is simple, easy to control, the raw materials are readily available, the cost is low, and it is suitable for continuous large-scale batch production, making it easy to operate and promote. In addition, the single-atom nickel-modified crystalline carbon nitride nanowire array photocatalytic material can be used to degrade difficult-to-degrade pollutants in water, such as enrofloxacin, ofloxacin, and tetracycline, with good results.

[0006] In order to solve the above technical problems, the present invention provides a single-atom nickel-modified crystalline carbon nitride nanowire array photocatalytic material, in which the single-atom nickel is uniformly dispersed on the highly crystalline carbon nitride nanowires.

[0007] The single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, further, the single-atom nickel loading is 1%-20%.

[0008] As a general technical concept, the application further provides a preparation method of the single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, which comprises the following steps:

[0009] S1, suspending the crystalline carbon nitride nanowire array in deionized water to obtain a suspension;

[0010] S2, adding the nickel nitrate solution drop by drop into the suspension, fully stirring, and annealing to obtain the single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material.

[0011] The preparation method of the single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, the preparation method of the crystalline carbon nitride nanowire array in S1 is as follows:

[0012] S1-1, calcining melamine at 400-600 DEG C for 6-8 hours to obtain a crystalline carbon nitride precursor;

[0013] S1-2, mixing and grinding the crystalline carbon nitride precursor with potassium chloride and lithium chloride, and calcining at 400-600 DEG C for 4-6 hours to obtain the crystalline carbon nitride.

[0014] The preparation method of the single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, in S1-2, the molar ratio of the potassium chloride and the lithium chloride is 1-4:5.

[0015] The preparation method of the single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, in S1-2, the calcining is carried out in a muffle furnace, and the heating rate in the muffle furnace is 2-5 DEG C / min.

[0016] The preparation method of the single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, the single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material in S2 is as follows:

[0017] S2-1, adding the nickel nitrate solution drop by drop into the crystalline carbon nitride suspension, and obtaining a yellow powder after magnetic stirring;

[0018] S2-2, placing the yellow powder in a tube furnace, and obtaining the single-atom nickel modified crystalline carbon nitride nanowire array under an inert atmosphere at 100-200 DEG C for 1-2 hours.

[0019] Further, the preparation method of the single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material in S2 is as follows:

[0020] S2-1, adding nickel nitrate solution drop by drop into the crystalline carbon nitride suspension, stirring by magnetic force for 10-24h, and obtaining yellow powder after washing and drying;

[0021] S2-2, obtaining monatomic nickel modified crystalline carbon nitride nanowire array by keeping the yellow powder in a tube furnace at 100-200℃ for 1-2h under inert atmosphere.

[0022] The preparation method of the monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material, in the S2-1, the concentration of the nickel nitrate solution is 0.5-2mol / L.

[0023] The preparation method of the monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material, in the S2-2, the heating rate of the tube furnace is 5-10℃ / min.

[0024] As a general technical concept, the application also provides an application of the monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material in degrading antibiotics in wastewater under simulated light and actual natural light conditions, and the application method is as follows:

[0025] (1) adding the monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material into the wastewater, and stirring in the dark to reach adsorption equilibrium;

[0026] (2) performing photocatalytic reaction under visible light.

[0027] (3) performing photocatalytic reaction under actual natural light.

[0028] The application of the monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material in degrading antibiotics in wastewater, the stirring time is 0.1-0.6h.

[0029] The application of the monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material in degrading antibiotics in wastewater, the visible light is λ≥400nm, and the photocatalytic reaction time is 5-20min.

[0030] Compared with the prior art, the application has the following advantages:

[0031] (1) The application provides a single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, single-atom nickel is uniformly dispersed in crystalline carbon nitride, promotes the visible light absorption capacity of the material, increases the charge density, promotes the separation and transfer of photo-generated electrons and holes. Through the strong coordination between nitrogen atoms and metal nickel atoms, the aggregation of single-atom metal centers in the surface catalysis process is inhibited, which is beneficial to the synthesis of high-load single-atom catalyst. The introduction of metal nickel atoms into the carbon nitride framework can improve the catalytic activity of carbon nitride, adjust the band gap structure, expand the light absorption range, and accelerate the charge transfer. The existence of the electron-rich nitrogen site in carbon nitride can provide an ideal place for metal nickel atom combination, thereby realizing the anchoring of uniformly dispersed metal nickel atoms. As a bridge for charge transfer, the nickel-nitrogen bond provides a rich electronic transmission channel and a catalytically active site, realizing efficient degradation of pollutants.

[0032] (2) The application provides a single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material. A simple strategy is developed to synthesize highly crystalline carbon nitride. Because amorphous carbon nitride with a large number of defects exhibits rapid recombination of electron-hole pairs and low charge carrier mobility, carbon nitride exhibits low photocatalytic degradation activity, especially for highly resistant organic pollutants. The present application greatly improves the photocatalytic activity of carbon nitride by increasing the crystallinity of carbon nitride and minimizing the defects in the structure. Highly crystalline graphite carbon nitride with reduced structural defects can greatly inhibit electron-hole recombination and exhibit significantly enhanced photocatalytic activity. Compared with amorphous carbon nitride and non-single-atom loaded crystalline carbon nitride, the single-atom loaded crystalline carbon nitride photocatalyst of the present application exhibits superior photocatalytic activity.

[0033] (3) The application provides a single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, which takes crystalline carbon nitride nanowire array as a base material. The direct one-dimensional electron channel of the unique nanowire array structure can realize effective charge transfer and shorten ion transfer. The large specific surface area is beneficial to electron / mass transfer and exposure of single-atom nickel sites. More active sites can more effectively absorb visible light and provide more contact area for reactants. The well-arranged one-dimensional semiconductor array has good electronic and optical properties. Due to the quantum size effect, the nanowire array structure is more conducive to the directional migration of charge carriers, reduces charge recombination, and results in excellent charge transport performance.

[0034] (4) The application provides a preparation method of single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, which is capable of synthesizing highly crystalline carbon nitride at low cost and in a controllable manner, and uniformly dispersing single-atom nickel on the crystalline carbon nitride. The preparation process is simple, easy to control, and suitable for continuous mass production, and the heating temperature is low, so that the operation and popularization are facilitated. The whole preparation process is simple and easy to control, low in energy consumption and cost, meets the actual production needs, and is conducive to large-scale popularization.

[0035] (5) The application provides an application of single-atom nickel modified crystalline carbon nitride nanowire array photocatalytic material, which can realize efficient degradation of antibiotic wastewater under simulated light and natural light conditions, has stable photocatalytic performance, strong corrosion resistance, high degradation efficiency, and good practical application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below in combination with the drawings in the embodiments of the application.

[0037] Figure 1 The scanning electron microscope images of monomer carbon nitride of the present application comparative example 1, crystalline carbon nitride of the present application example 1 and single-atom nickel modified crystalline carbon nitride.

[0038] Figure 2 The transmission electron microscope and high-resolution transmission electron microscope images of monomer carbon nitride of the present application comparative example 1, crystalline carbon nitride of the present application example 1 and single-atom nickel modified crystalline carbon nitride.

[0039] Figure 3 The spherical aberration correction high-angle annular dark field imaging scanning transmission electron microscope image of single-atom nickel modified crystalline carbon nitride of the present application example 1.

[0040] Figure 4 The X-ray diffraction comparison spectrum of monomer carbon nitride of the present application comparative example 1, crystalline carbon nitride of the present application example 1 and single-atom nickel modified crystalline carbon nitride photocatalytic material.

[0041] Figure 5 The DRS comparison graph of monomer carbon nitride, crystalline carbon nitride and single-atom nickel modified crystalline carbon nitride.

[0042] Figure 6 The time-degradation efficiency relationship graph corresponding to the degradation of enrofloxacin wastewater by monomer carbon nitride, crystalline carbon nitride and single-atom nickel modified crystalline carbon nitride photocatalyst in the application method of the present application example 2.

[0043] Figure 7The time-degradation efficiency relationship diagram corresponding to the degradation of ofloxacin wastewater by the monomer carbon nitride, the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride photocatalyst in the application method of the embodiment 2 of the present application.

[0044] Figure 8 The time-degradation efficiency relationship diagram corresponding to the degradation of tetracycline wastewater by the monomer carbon nitride, the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride photocatalyst in the application method of the embodiment 2 of the present application.

[0045] Figure 9 The cycle experiment diagram of the single-atom nickel modified crystalline carbon nitride photocatalyst degrading enrofloxacin

[0046] Figure 10 The time-degradation efficiency relationship diagram corresponding to the degradation of enrofloxacin, ofloxacin and tetracycline wastewater by the single-atom nickel modified crystalline carbon nitride photocatalyst in the application method of the embodiment 3 of the present application under the irradiation of actual natural light. DETAILED DESCRIPTION

[0047] The present application is further described below in conjunction with the drawings of the specification and specific preferred embodiments, but the protection scope of the present application is not limited thereby.

[0048] The materials and instruments used in the following embodiments are all commercially available.

[0049] Comparative Example 1

[0050] A photocatalyst of the present application is a monomer carbon nitride (BCN) photocatalyst without modification, and the preparation method thereof is as follows:

[0051] 4g of melamine was placed in a crucible, and heated to 500℃ at a heating rate of 12℃ / min in a muffle furnace, and kept at 500℃ for 4h, the whole process was carried out under the protection of nitrogen, and after natural cooling, it was taken out and ground with a mortar to obtain a yellow powder sample, which is monomer carbon nitride (BCN).

[0052] Example 1

[0053] A single-atom nickel modified crystalline carbon nitride nanowire array photocatalyst of the present application, and the preparation method thereof comprises the following steps:

[0054] (1) Preparation of crystalline carbon nitride (CCN):

[0055] 1.1, 4g of melamine was placed in a crucible, and heated to 500℃ at a heating rate of 12℃ / min in a muffle furnace, and kept at 500℃ for 4h, and after natural cooling, it was taken out and ground with a mortar to obtain a light yellow powder.

[0056] 1.2, take 600 mg of the above light yellow powder, mix with 3.3 g of potassium chloride, 2.7 g of lithium chloride, and grind, put the mixture into a crucible, and place it in a muffle furnace, heat to 550℃ at a heating rate of 2.3℃ / min, and keep at 550℃ for 4 h, the whole process is carried out under the protection of nitrogen, after natural cooling, wash it with deionized water and methanol solution for three times respectively, dry and grind to obtain crystalline carbon nitride (CCN).

[0057] (2) Single-atom nickel modified crystalline carbon nitride nanowire array (Ni-CCN):

[0058] 2.1, disperse 400 mg of crystalline carbon nitride in 50 mL of aqueous solution, add 0.1 g / mol of nickel nitrate solution dropwise to the crystalline carbon nitride suspension, magnetically stir for 12 h, dry after washing with deionized water to obtain a yellow powder.

[0059] obtain a yellow powder;

[0060] 2.2, place the yellow powder in a tube furnace, anneal to 125℃ at a heating rate of 5℃ / min under an inert atmosphere, and keep at 125℃ for 2 h, take it out after natural cooling to obtain a single-atom nickel modified crystalline carbon nitride nanowire array (Ni-CCN)

[0061] Experimental Example 1: Scanning electron microscopy of monomer carbon nitride of Comparative Example 1 and crystalline carbon nitride and single-atom nickel modified crystalline carbon nitride of Example 1.

[0062] Figure 1 Scanning electron microscope (SEM) images of monomer carbon nitride of Comparative Example 1 and crystalline carbon nitride and single-atom nickel modified crystalline carbon nitride of Example 1 of the present application, wherein (a) is monomer carbon nitride, (b) is crystalline carbon nitride, and (c) is single-atom nickel modified crystalline carbon nitride.

[0063] Figure 2 Transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) images of monomer carbon nitride of Comparative Example 1 and crystalline carbon nitride and single-atom nickel modified crystalline carbon nitride of Example 1 of the present application, wherein (a) is the transmission electron microscope image of monomer carbon nitride, (b) is the high-resolution transmission electron microscope image; (c) is the transmission electron microscope image of crystalline carbon nitride, (d) is the high-resolution transmission electron microscope, and (e) is the selected area electron diffraction pattern; (f) is the transmission electron microscope image of single-atom nickel modified crystalline carbon nitride, (g) is the high-resolution transmission electron microscope, and (h) is the selected area electron diffraction pattern.

[0064] From Figure 1 and Figure 2It can be seen that the monomer carbon nitride presents a block aggregate structure without obvious lattice diffraction stripes. The crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride present a nanowire uniform array structure, and each nanowire has a clear one-dimensional structure and a smooth surface. High-resolution transmission electron microscopy shows that the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride have obvious lattice stripes, indicating the high crystallinity of the carbon nitride, and the 0.33 nm corresponding lattice stripe is due to the interlayer spacing of the carbon nitride sheet, and the 0.98 nm corresponding lattice stripe is derived from the periodicity in the plane. In addition, combined with selected area electron diffraction (SAED), it is found that the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride both have obvious diffraction spots, showing a ring pattern, indicating the polycrystalline nature of the carbon nitride. The above results successfully verify the successful preparation of the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride.

[0065] Figure 3 The spherical aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of the single-atom nickel modified crystalline carbon nitride of Example 1 of the present application is shown. The distribution of metal atoms on the carrier surface is observed by spherical aberration-corrected electron microscopy, which is used in the present application to observe whether the metal atoms are aggregated, proving the successful preparation of the single-atom catalyst. As shown in FIG. 1, the nickel atoms are imaged in the form of a spot, and the isolated light points represent isolated atoms, and the bright spots represent nickel of atomic size, which are uniformly distributed and isolated on the carrier surface, proving that the nickel species exists in the form of single atoms. This indicates the successful preparation of the single-atom nickel modified crystalline carbon nitride. Figure 3

[0066] Experimental Example 2: The monomer carbon nitride of Comparative Example 1, the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride photocatalytic material in Example 1 were subjected to X-ray scanning.

[0067] Figure 4 The X-ray diffraction (XRD) comparative spectrum of the monomer carbon nitride of Comparative Example 1 and the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride photocatalytic material in Example 1 of the present application is shown. It can be seen from the figure that two obvious XRD diffraction peaks belonging to the (100) and (002) crystal planes of the graphite phase carbon nitride appear at 13° and 27°, confirming that the prepared product is g-C3N4. Comparing the 27° peaks of the monomer carbon nitride, the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride, the peak becomes narrower and the intensity becomes stronger, indicating that the crystallinity of the carbon nitride is improved. In addition, comparing the 13° peaks of the monomer carbon nitride, the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride, the peak shifts to a low angle, corresponding to the improvement of the crystallinity. This proves the successful preparation of the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride.

[0068] ​Experimental Example 3: The monomer carbon nitride of Comparative Example 1, the crystalline carbon nitride in Example 1 and the single-atom nickel modified crystalline carbon nitride photocatalytic material were detected for specific surface area, pore volume and pore size.

[0069] The monomer carbon nitride of Comparative Example 1, the crystalline carbon nitride in Example 1 and the single-atom nickel modified crystalline carbon nitride photocatalytic material were detected for specific surface area, pore volume and pore size. The specific surface area of the monomer carbon nitride was 9 m 2 / g, the pore volume was 0.05 cm 3 / g, and the pore size was 10.5 nm; while the specific surface area of the crystalline carbon nitride was 36 m 2 / g, the pore volume was 0.14 cm 3 / g, and the pore size was 13.7 nm; the specific surface area of the single-atom nickel modified crystalline carbon nitride photocatalytic material was 45 m 2 / g, the pore volume was 0.16 cm 3 / g, and the pore size was 16 nm; thus, the single-atom nickel modified crystalline carbon nitride photocatalytic material has the advantages of large surface area, large pore volume and large pore size.

[0070] Experimental Example 4: The monomer carbon nitride of Comparative Example 1, the crystalline carbon nitride in Example 1 and the single-atom nickel modified crystalline carbon nitride photocatalytic material were compared by DRS.

[0071] Figure 5 The DRS comparison chart of the monomer carbon nitride, the crystalline carbon nitride and the single-atom nickel modified crystalline carbon nitride of the present application is shown in the figure, from which it can be seen that the monomer carbon nitride has an absorption wavelength of about 450 nm, the crystalline carbon nitride increases the light absorption range, and the single-atom nickel modified crystalline carbon nitride further widens the light absorption range of the material and improves the light energy utilization rate.

[0072] Example 2

[0073] An application of the single-atom nickel modified crystalline carbon nitride photocatalyst of Example 1 in degrading antibiotic wastewater, the application method is:

[0074] In the experiment, 30 mg of single-atom nickel modified crystalline carbon nitride photocatalyst was added to 100 mL of antibiotic wastewater with a concentration of 10 mg / L, and stirred in the dark for 30 min to achieve adsorption-desorption equilibrium. Under simulated visible light irradiation, every 3 min, 0.5 mL of the mixture was taken, and the concentration of the antibiotic in the solution was determined by high performance liquid chromatography, and the degradation efficiency was calculated.

[0075] At the same time, the monomeric carbon nitride of Comparative Example 1 and the crystalline carbon nitride of Example 1 were subjected to the same application and their degradation efficiency was calculated. The time-degradation efficiency relationship diagram corresponding to the degradation of enrofloxacin wastewater by monomeric carbon nitride, crystalline carbon nitride and crystalline carbon nitride modified with single-atom nickel is shown in FIG. Figure 6 The time-degradation efficiency relationship of monomeric carbon nitride, crystalline carbon nitride and single-atom nickel-modified crystalline carbon nitride photocatalysts for the degradation of ofloxacin wastewater is shown in Figure 7 The time-degradation efficiency relationship of monomeric carbon nitride, crystalline carbon nitride and single-atom nickel-modified crystalline carbon nitride photocatalysts for tetracycline wastewater degradation is shown in Figure 8 As shown. Figure 6 It can be seen that after 15 minutes of illumination, the degradation efficiency of enrofloxacin by the single-atom nickel-modified crystalline carbon nitride photocatalyst can reach 97%, followed by crystalline carbon nitride, while the degradation efficiency of monomeric carbon nitride on enrofloxacin is only 11%. Figure 7 It can be seen that after 15 minutes of illumination, the degradation efficiency of ofloxacin by the single-atom nickel-modified crystalline carbon nitride photocatalyst can reach 97%, followed by crystalline carbon nitride, while the degradation efficiency of ofloxacin by monomeric carbon nitride is only 7%. Figure 8 The results show that after 15 minutes of illumination, the degradation of tetracycline by the single-atom nickel-modified crystalline carbon nitride photocatalyst reached 100%, followed by crystalline carbon nitride, while the degradation efficiency of carbon nitride alone was only 29%. The results show that the single-atom nickel-modified crystalline carbon nitride photocatalyst has a high degradation efficiency for pollutants. Figure 9 This is a cyclic experimental diagram of the degradation of enrofloxacin by a single-atom nickel modified crystalline carbon nitride photocatalyst. As can be seen from the figure, the single-atom nickel modified crystalline carbon nitride photocatalyst has a good degradation effect on enrofloxacin after being recycled four times.

[0076] Example 3

[0077] An application of the single-atom nickel-modified crystalline carbon nitride photocatalyst of Example 1 in degrading antibiotic wastewater under natural light conditions, wherein the application method is as follows:

[0078] In the experiment, 30 mg of a single-atom nickel-modified crystalline carbon nitride photocatalyst was added to 100 mL of antibiotic wastewater at a concentration of 10 mg / L. The solution was stirred in the dark for 30 minutes to achieve adsorption-desorption equilibrium. Under natural light, 0.5 mL of the mixture was sampled every 1 minute, and the antibiotic concentration in the solution was determined using high-performance liquid chromatography to calculate the degradation efficiency.

[0079] In an ideal case, the photocatalytic water treatment process is powered by natural sunlight. Therefore, we take natural sunlight as the energy to evaluate the feasibility of single-atom nickel modified crystalline carbon nitride photocatalyst in practical application. The time-degradation efficiency relationship diagram of single-atom nickel modified crystalline carbon nitride photocatalyst in the degradation of enrofloxacin, ofloxacin and tetracycline wastewater under actual natural light irradiation is shown in Figure 10 It can be known from Figure 10 that after 5 min of irradiation, the degradation of enrofloxacin by single-atom nickel modified crystalline carbon nitride photocatalyst can reach 96%, the degradation of ofloxacin by single-atom nickel modified crystalline carbon nitride photocatalyst can reach 90% after 5 min of irradiation, and the degradation of tetracycline by single-atom nickel modified crystalline carbon nitride photocatalyst can reach 97% after 5 min of irradiation. Single-atom nickel modified crystalline carbon nitride photocatalyst exhibits excellent catalytic activity in the degradation of enrofloxacin, ofloxacin and tetracycline under natural sunlight irradiation, indicating that the system can be effectively used for the remediation of antibiotic wastewater under natural sunlight conditions.

[0080] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiment, it is not intended to limit the present application. Any person skilled in the art, without departing from the spirit and technical scheme of the present application, can make many possible changes and modifications to the technical scheme of the present application by using the disclosed methods and technical contents, or modify equivalent embodiments. Therefore, any simple modification, equivalent replacement, equivalent change and modification of the above embodiments made according to the technical essence of the present application, without departing from the technical scheme of the present application, still belongs to the protection scope of the technical scheme of the present application.

Claims

1. The use of monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material in the degradation of antibiotics in wastewater under simulated visible light irradiation and actual natural light irradiation conditions, characterized in that, The application is: The monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material is added into antibiotic wastewater, stirred in the dark to reach adsorption equilibrium, and subjected to photocatalytic reaction under simulated visible light irradiation or actual natural light irradiation; the monatomic nickel is uniformly dispersed on the crystalline carbon nitride nanowire array in the monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material; and the preparation method of the monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material is as follows: S1, suspending the crystalline carbon nitride nanowire array in deionized water to obtain a crystalline carbon nitride suspension; S2, adding a nickel nitrate solution drop by drop into the crystalline carbon nitride suspension, magnetically stirring for 10-24 hours, and cleaning and drying to obtain a yellow powder; S3, placing the yellow powder in a tube furnace, and heat treating at 100-200 DEG C under an inert atmosphere for 1-2 hours to obtain the monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material; and the preparation method of the crystalline carbon nitride nanowire array is as follows: S3-1, calcining melamine at 400-600 DEG C for 6-8 hours to obtain a crystalline carbon nitride precursor; S3-2, mixing and grinding the crystalline carbon nitride precursor with potassium chloride and lithium chloride, and calcining at 400-600 DEG C for 4-6 hours to obtain the crystalline carbon nitride nanowire array.

2. Use according to claim 1, characterized in that, In the stirring to reach adsorption equilibrium step in the dark, the stirring time is 0.1-0.6 hours; the visible light has a wavelength of greater than or equal to 400 nm; and the photocatalytic reaction time is 5-20 minutes.

3. Use according to claim 1, characterized in that, The monatomic nickel modified crystalline carbon nitride nanowire array photocatalytic material has a monatomic nickel loading of 1-20%.

4. Use according to claim 1, characterized in that, In S3-2, the molar ratio of the potassium chloride to the lithium chloride is 1-4:5; And / or, in S3-2, the calcining is performed in a muffle furnace, and the temperature rising rate in the muffle furnace is 2-5 DEG C per minute.

5. The use according to claim 1, characterized in that, The concentration of the nickel nitrate solution is 0.5-2 mol / L; And / or, the temperature rising rate of the tube furnace is 5-10 DEG C per minute.

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