Cobalt-manganese dual-atom catalyst based on carbon nitride with interlayer confinement effect, preparation method and application

Abstract

The present invention provides a carbon nitride-based cobalt-manganese dual-atom catalyst with an interlayer confinement effect, a preparation method and an application thereof, which includes carbon nitride having a two-dimensional layered structure, and Co and Mn atoms are intercalated between the carbon nitride layers. The CoMn dual-atom catalytic system confined between the carbon nitride layers has excellent performance in degrading carbamazepine and selectively degrading different organic pollutants.

Description

Technical Field

[0001] The present invention belongs to the field of carbon nitride-based cobalt-manganese dual-atom catalysts for photo-Fenton reactions, and particularly relates to a carbon nitride-based cobalt-manganese dual-atom catalyst with an interlayer confinement effect, a preparation method thereof, and an application thereof. Background Art

[0002] The photo-Fenton reaction that generates free radicals by catalyzing persulfate (PMS) to achieve efficient degradation of organic pollutant molecules has received extensive attention. Designing efficient catalysts to improve the PMS activation efficiency and achieve efficient degradation of organic molecules is the focus of the research on the PMS photo-Fenton reaction. As a new type of photocatalyst, carbon nitride (CN) has received great attention in the catalytic field due to its non-metallic properties, low price, good chemical stability, adjustable bandgap, non-toxicity, and easy synthesis. Its interlayer confinement strategy is based on the unique open confinement space of two-dimensional layered materials, which can dynamically regulate the interlayer spacing in real time, further promoting the efficient, stable, and directional activation of PMS. The latest progress of CN-based catalysts for photo-Fenton reactions includes various modification strategies, such as morphology control, non-metal doping, organic molecule doping, loading sub-nanoscale auxiliary materials containing metals (such as quantum dots, organic molecules, metal cations, and single atoms), and composite nanomaterials to improve the catalytic performance of CN.

[0003] The photo-Fenton reactions based on dual-atom catalysts are currently all surface catalytic reactions. If the dual-atom catalytic strategy and the interlayer confinement catalytic strategy can be combined to confine dual atoms in the interlayer of two-dimensional layered materials, it is expected to further improve the photo-Fenton reactivity and selectivity on the basis of inheriting the high activity of dual-atom catalysts. However, an inappropriate method for confining dual atoms in the interlayer easily causes the collapse of the dual-atom catalyst structure, and it is difficult to prepare an interlayer-confined dual-atom catalyst using the currently mature surface dual-atom catalyst method.

[0004] Therefore, there is an urgent need to develop a CoMn dual-atom catalyst with an interlayer confinement effect for the efficient and selective treatment of wastewater. Summary of the Invention

[0005] The object of the present invention is to provide a carbon nitride-based cobalt-manganese dual-atom catalyst (CoMn / CN inter ) with an interlayer confinement effect, including carbon nitride with a two-dimensional layered structure, and Co and Mn atoms are intercalated between the carbon nitride layers. The CoMn dual-atom catalytic system confined in the interlayer of the above carbon nitride substrate has excellent performance in degrading carbamazepine (CBZ) and selectively degrading different organic pollutants.

[0006] The object of the present invention is achieved through the following technical solutions.

[0007] A preparation method of a carbon nitride-based cobalt-manganese dual-atom catalyst with an interlayer confinement effect includes the following:

[0008] After calcining urea at a high temperature of 450-650 °C for 2 h, it is cooled to room temperature, washed alternately with ethanol and water and then dried to prepare a carbon nitride precursor; the carbon nitride precursor, KCl and LiCl are fully ground and mixed, and calcined at a high temperature under a nitrogen atmosphere, cooled to room temperature, washed alternately with ethanol and water and then dried to prepare carbon nitride; the mass ratio of the carbon nitride precursor, KCl and LiCl is 1:1-3:1-3

[0009] Add ammonia water to the mixed solution of MnCl 2 and CoCl 2 to prepare a CoMn-NH 4 + complex solution; the ratio of the MnCl 2 and CoCl 2 is 1:0.5-1.5;

[0010] Stir the CoMn-NH 4 + complex solution, carbon nitride and carboxymethyl cellulose at room temperature for 12-36 h, wash alternately with ethanol and water, grind thoroughly after drying, and calcine at a low temperature of 300-400 °C for 2 h under a nitrogen atmosphere and then cool to room temperature, with a heating rate of 5 °C / min; wash alternately with ethanol and water and then dry to obtain CoMn / CN inter .

[0011] As a more preferred technical solution of the present invention, the calcination temperature of the urea is 550 °C.

[0012] As a more preferred technical solution of the present invention, the mass ratio of the KCl and LiCl is 1:1.

[0013] As a more preferred technical solution of the present invention, the mass ratio of the carbon nitride precursor, KCl and LiCl is 1:2:2.

[0014] As a more preferred technical solution of the present invention, the low-temperature calcination temperature of the CoMn-NH 4 + complex solution, carbon nitride and carboxymethyl cellulose after grinding is 350 °C.

[0015] Another object of the present invention is to provide the application of the above-mentioned carbon nitride-based cobalt-manganese dual-atom catalyst with an interlayer confinement effect in the photo-Fenton removal of organic pollutants in water to achieve the selective degradation of different organic pollutants.

[0016] As a more preferred technical solution of the present invention, the organic pollutant is CBZ.

[0017] Beneficial effects:

[0018] The present invention constructs for the first time a CoMn dual-atom catalyst confined between layers of two-dimensional carbon nitride with high activity and selectivity; the prepared optimal CoMn dual-atom catalyst confined between layers of carbon nitride exhibits excellent CBZ degradation efficiency, which is 24.3%, 94.5% and 31.1% higher than that of the CoMn dual-atom catalyst coordinated on the surface of carbon nitride, the Co single-atom catalyst confined between layers of carbon nitride and the Mn single-atom catalyst confined between layers of carbon nitride, respectively.

[0019] The CoMn dual-atom catalyst confined between layers of carbon nitride of the present invention has good anti-interference performance against anions (such as SO 4 2− , NO 3 − and Cl − etc.) and water matrices (such as tap water and secondary effluent, etc.). Description of the Drawings

[0020] Figure 1 is the morphological characterization of CoMn / CN in Example 1. Among them, a is the aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-STEM) image of CoMn / CN in Example 1, and b is the mapping image of CoMn / CN in Example 1; inter The CoMn / CN in Example 1 inter is the aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-STEM) image, and b is the mapping image of CoMn / CN in Example 1; inter

[0021] Figure 2 is the CoMn / CN in Example 1 inter , CN in Comparative Example 1, Co / CN in Comparative Example 2 inter , Co / CN in Comparative Example 3 inter , CoMn / CN in Comparative Example 4 surf X-ray diffraction (XRD) patterns;

[0022] Figure 3 is the CoMn / CN in Example 1 inter， , CN in Comparative Example 1, Co / CN in Comparative Example 2 inter , Co / CN in Comparative Example 3 inter , CoMn / CN in Comparative Example 4 surf Fourier transform infrared (FT-IR) spectra;

[0023] Figure 4 CoMn / CN in Example 1 inter and CoMn / CN in Comparative Example 4 surf X-ray photoelectron spectroscopy (XPS) of Co2p and Mn2p before and after etching;

[0024] Figure 5For the CN of Comparative Example 1, the CN-1:1:1 of Comparative Example 2, the CN-1:3:3 of Comparative Example 3, the CN-450 °C of Comparative Example 4, and the CN-650 °C of Comparative Example 5, the efficiency and rate of photocatalytic Fenton for removing CBZ;

[0025] Figure 6 For CoMn / CN of Example 1 inter , CoMn / CN of Example 2 inter -1:0.5, CoMn / CN of Example 3 inter -1:1.5, CoMn / CN of Example 4 inter -NS, CoMn / CN of Example 5 inter -24 h and CoMn / CN of Example 6 inter -36 h, CoMn / CN of Example 7 inter -300 °C and CoMn / CN of Example 8 inter -400 °C, the efficiency and rate of photocatalytic Fenton for removing CBZ;

[0026] Figure 7 For CoMn / CN of Example 1 inter , the CN of Comparative Example 1, Co / CN of Comparative Example 6 inter , Mn / CN of Comparative Example 7 inter , CoMn / CN of Comparative Example 8 surf The efficiency and rate of photocatalytic Fenton for removing CBZ;

[0027] Figure 8 For CoMn / CN of Example 1 inter and CoMn / CN of Comparative Example 8 surf The efficiency of removing CBZ in different systems;

[0028] Figure 9 For CoMn / CN of Example 1 inter and CoMn / CN of Comparative Example 8 surf The removal efficiency of CBZ in the presence of different inorganic salts and humic acids;

[0029] Figure 10 For CoMn / CN of Example 1 inter and CoMn / CN of Comparative Example 8 surf The efficiency of photocatalytic Fenton degradation of different organic pollutants;

[0030] Figure 11 For CoMn / CN of Example 1 inter The cyclic degradation efficiency and ion dissolution concentration;

[0031] Figure 12 For CoMn / CN of Example 1inter XRD patterns and FT-IR spectra before and after Specific Embodiments

[0032] The following further describes the specific embodiments of the present invention in conjunction with the accompanying drawings. It should be noted here that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation on the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention. For those not specified in the embodiments, the techniques or conditions described in the literature in the art or according to the product specifications are followed. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial procurement.

[0034] Comparative Example 1

[0035] 20.0 g of urea was placed in a crucible and placed in a muffle furnace. It was heated to 550 °C at a heating rate of 5 °C / min and calcined for 2 h. After cooling to room temperature, it was ground to obtain a light yellow sample.

[0036] 1.0 g of the above sample, 2.0 g of KCl and 2.0 g of LiCl were thoroughly ground and mixed, then transferred to a porcelain boat. In a tubular furnace under a nitrogen atmosphere, it was heated to 550 °C at a rate of 5 °C / min and held for 2 h. After cooling to room temperature, the obtained sample was washed alternately with ethanol and water 6 times, vacuum dried at 60 °C for 12 h, and ground to obtain a yellow sample, denoted as CN.

[0037] Comparative Example 2

[0038] 20.0 g of urea was placed in a crucible and placed in a muffle furnace. It was heated to 550 °C at a heating rate of 5 °C / min and calcined for 2 h. After cooling to room temperature, it was ground to obtain a light yellow sample.

[0039] 1.0 g of the above sample, 1.0 g of KCl and 1.0 g of LiCl were thoroughly ground and mixed, then transferred to a porcelain boat. In a tubular furnace under a nitrogen atmosphere, it was heated to 550 °C at a rate of 5 °C / min and held for 2 h. After cooling to room temperature, the obtained sample was washed alternately with ethanol and water 6 times, vacuum dried at 60 °C for 12 h, and ground to obtain a yellow sample, denoted as CN-1:1:1.

[0040] Comparative Example 3

[0041] 20.0 g of urea was placed in a crucible and placed in a muffle furnace. It was heated to 550 °C at a heating rate of 5 °C / min and calcined for 2 h. After cooling to room temperature, it was ground to obtain a light yellow sample.

[0042] 1.0 g of the above sample, 3.0 g of KCl, and 3.0 g of LiCl were thoroughly ground and mixed, then transferred to a porcelain boat. In a tube furnace under a nitrogen atmosphere, the temperature was raised to 550 °C at a rate of 5 °C / min, held for 2 h, cooled to room temperature. The obtained sample was washed alternately with ethanol and water 6 times, dried in vacuum at 60 °C for 12 h, and ground to obtain a yellow sample, denoted as CN-1:3:3.

[0043] Comparative Example 4

[0044] 20.0 g of urea was placed in a crucible and placed in a muffle furnace. The temperature was raised to 550 °C at a heating rate of 5 °C / min, calcined for 2 h, cooled to room temperature, and then ground to obtain a pale yellow sample.

[0045] 1.0 g of the above sample, 3.0 g of KCl, and 3.0 g of LiCl were thoroughly ground and mixed, then transferred to a porcelain boat. In a tube furnace under a nitrogen atmosphere, the temperature was raised to 450 °C at a rate of 5 °C / min, held for 2 h, cooled to room temperature. The obtained sample was washed alternately with ethanol and water 6 times, dried in vacuum at 60 °C for 12 h, and ground to obtain a yellow sample, denoted as CN-450 °C.

[0046] Comparative Example 5

[0047] 20.0 g of urea was placed in a crucible and placed in a muffle furnace. The temperature was raised to 550 °C at a heating rate of 5 °C / min, calcined for 2 h, cooled to room temperature, and then ground to obtain a pale yellow sample.

[0048] 1.0 g of the above sample, 3.0 g of KCl, and 3.0 g of LiCl were thoroughly ground and mixed, then transferred to a porcelain boat. In a tube furnace under a nitrogen atmosphere, the temperature was raised to 650 °C at a rate of 5 °C / min, held for 2 h, cooled to room temperature. The obtained sample was washed alternately with ethanol and water 6 times, dried in vacuum at 60 °C for 12 h, and ground to obtain a yellow sample, denoted as CN-650 °C.

[0049] Comparative Example 6

[0050] 0.9085 g of CoCl 2 37.5 mL of ultrapure water was added and stirred until completely dissolved to prepare a 0.1 M CoCl 2 aqueous solution. 2 mL of 27% ammonia water was slowly added dropwise to the above 0.1 M CoCl 2 aqueous solution. During the addition, it was stirred thoroughly until the precipitate disappeared to form a stable Co-NH 4 + complex solution. 200 mg of CN was added to 200 mL of ultrapure water and stirred for dispersion. The Co-NH 4 +The complex solution was slowly added to the completely dispersed CN solution, and then 2 mg of carboxymethyl cellulose was added. The mixture was stirred at room temperature for 24 h. The reaction solution was washed alternately with ethanol and water 6 times, vacuum dried at 60 °C for 12 h. After cooling to room temperature, it was ground thoroughly and transferred to a porcelain boat. In a tubular furnace under a nitrogen atmosphere, it was heated to 550 °C at a rate of 5 °C / min and held for 2 h. After cooling to room temperature, the obtained sample was washed alternately with ethanol and water 6 times, vacuum dried at 60 °C for 12 h, and ground to obtain a black sample, denoted as Co / CN inter 。

[0051] Comparative Example 7

[0052] 0.7560 g of MnCl 2 37.5 mL of ultrapure water was added and stirred until completely dissolved to prepare a 0.1 M CoCl 2 aqueous solution. 2 mL of 27% ammonia water was slowly added dropwise to the above 0.1 M MnCl 2 aqueous solution. During the addition, it was stirred thoroughly until the precipitate disappeared to form a stable Co-NH 4 + complex solution. 200 mg of CN was added to 200 mL of ultrapure water and stirred for dispersion. The Co-NH 4 + complex solution was slowly added to the completely dispersed CN solution, and then 2 mg of carboxymethyl cellulose was added. The mixture was stirred at room temperature for 24 h. The reaction solution was washed alternately with ethanol and water 6 times, vacuum dried at 60 °C for 12 h. After cooling to room temperature, it was ground thoroughly and transferred to a porcelain boat. In a tubular furnace under a nitrogen atmosphere, it was heated to 550 °C at a rate of 5 °C / min and held for 2 h. After cooling to room temperature, it was ground to obtain a black sample, denoted as Co / CN inter 。

[0053] Comparative Example 8

[0054] 0.9085 g of CoCl 2 and 0.7560 g of MnCl 2 37.5 mL of ultrapure water was added and stirred until completely dissolved to prepare a 0.1 M CoCl 2 and MnCl 2 mixed aqueous solution. 200 mg of CN was added to 200 mL of ultrapure water and stirred for dispersion. The Co-NH 4 +The complex solution was slowly added to the completely dispersed CN solution, and stirred at room temperature for 24 h. The reacted solution was washed alternately with ethanol and water for 6 times, vacuum dried at 60 °C for 12 h. After cooling to room temperature, it was thoroughly ground and transferred to a porcelain boat. In a tubular furnace under a nitrogen atmosphere, it was heated to 550 °C at a rate of 5 °C / min and held for 2 h, then washed alternately with ethanol and water for 6 times, vacuum dried at 60 °C for 12 h. After cooling to room temperature, it was ground to obtain a black sample, denoted as CoMn / CN surf 。

[0055] Example 1

[0056] 0.9085 g of CoCl 2 and 0.7560 g of MnCl 2 were added to 37.5 mL of ultrapure water and stirred until completely dissolved to prepare a 0.1 M aqueous solution of CoCl 2 and a 0.1 M aqueous solution of MnCl 2 mixed solution. 2 mL of 27% ammonia water was slowly added dropwise to the above mixed aqueous solution, and stirred vigorously during the addition until the precipitate disappeared to form a stable Co-NH 4 + complex solution. 200 mg of CN was added to 200 mL of ultrapure water and stirred for dispersion. The Co-NH 4 + complex solution was slowly added to the CN solution prepared in Comparative Example 1 which was completely dispersed, and then 2 mg of carboxymethyl cellulose was added, and stirred at room temperature for 24 h. The reacted solution was washed alternately with ethanol and water for 6 times, vacuum dried at 60 °C for 12 h. After cooling to room temperature, it was thoroughly ground and transferred to a porcelain boat. In a tubular furnace under a nitrogen atmosphere, it was heated to 350 °C at a rate of 5 °C / min and held for 2 h, then washed alternately with ethanol and water for 6 times, vacuum dried at 60 °C for 12 h. After cooling to room temperature, it was ground to obtain a black sample, denoted as CoMn / CN inter 。

[0057] Example 2

[0058] The difference between this example and Example 1 is that: the molar ratio of CoCl 2 and MnCl 2 was changed from 1:1 to 1:0.5. A black sample was obtained, denoted as CoMn / CN inter -1:0.5.

[0059] Example 3

[0060] The difference between this example and Example 1 is that: the molar ratio of CoCl 2 and MnCl 2 was changed from 1:1 to 1:1.5. A black sample was obtained, denoted as CoMn / CN inter -1:1.5.

[0061] Example 4

[0062] The difference between this example and Example 1 is that during the room-temperature stirring of the CoMn-NH 4 + complex solution and carbon nitride, carboxymethyl cellulose was not added. A black sample was obtained and denoted as CoMn / CN inter -NS.

[0063] Example 5

[0064] The difference between this example and Example 1 is that the stirring time of the CoMn-NH 4 + complex solution with carbon nitride and carboxymethyl cellulose at room temperature was changed from 24 h to 12 h. A black sample was obtained and denoted as CoMn / CN inter -24h.

[0065] Example 6

[0066] The difference between this example and Example 1 is that the stirring time of the CoMn-NH 4 + complex solution with carbon nitride and carboxymethyl cellulose at room temperature was changed from 24 h to 36 h. A black sample was obtained and denoted as CoMn / CN inter -36h.

[0067] Example 7

[0068] The difference between this example and Example 1 is that the calcination temperature of the mixture of CoMn-NH 4 + complex, carbon nitride and carboxymethyl cellulose was changed from 350 °C to 300 °C. A black sample was obtained and denoted as CoMn / CN inter -300°C.

[0069] Example 8

[0070] The difference between this example and Example 1 is that the calcination temperature of the mixture of CoMn-NH 4 + complex, carbon nitride and carboxymethyl cellulose was changed from 350 °C to 400 °C. A black sample was obtained and denoted as CoMn / CN inter -400°C.

[0071] The AC-STEM of CoMn / CN inter of Example 1 is as shown in Figure 1 a. It can be seen that paired white bright spots appear in CoMn / CN inter of Example 1, proving the existence of diatoms. CoMn / CN interThe element mapping of AC-STEM is as shown in Figure 1 Figure b, indicating that the CoMn / CN of Example 1 inter is composed of Co, Mn, C, and N elements.

[0072] The CoMn / CN of Example 1 inter , the CN of Comparative Example 1, the Co / CN of Comparative Example 6 inter , the Mn / CN of Comparative Example 7 inter , the CoMn / CN of Comparative Example 8 surf The XRD results are as shown in Figure 2 Figure. The diffraction peaks at 13.0 and 27.5° correspond to the (100) and (002) crystal planes of CN, respectively. Due to the introduction of atoms, compared with the CN of Comparative Example 1, the Co / CN of Comparative Example 6 inter , the Mn / CN of Comparative Example 7 inter and the CoMn / CN of Comparative Example 8 surf show a significant weakening of these two peak signals.

[0073] The CoMn / CN of Example 1 inter， , the CN of Comparative Example 1, the Co / CN of Comparative Example 6 inter , the Mn / CN of Comparative Example 7 inter , and the CoMn / CN of Comparative Example 8 surf The FT-IR results are as shown in Figure 3 Figure. The samples of Example 1, Comparative Example 1, and Comparative Examples 6 to 8 all exhibit three infrared absorption peaks. The peak at 810 cm -1 is caused by the bending vibration of the s-triazine unit. The broad peak at 1211 - 1647 cm -1 originates from the C=N and C-N heterocyclic skeletons. The peak at 3047 - 3400 cm -1 corresponds to the -NH 2 and =NH bonds.

[0074] The CoMn / CN of Example 1 inter and the CoMn / CN of Comparative Example 8 surf The XPS results of Co2p and Mn2p before and after etching are as shown in Figure 4 Figure. Compared with the signal peak intensities of Co2p and Mn2p of the CoMn / CN of Example 1 before etching inter , the signal peak intensities of Co2p and Mn2p of the CoMn / CN of Example 1 after etching inter are enhanced (Figures a and c). Compared with the signal peak intensities of Co2p and Mn2p of the CoMn / CN of Comparative Example 8 before etching surf , the signal peak intensities of Co2p and Mn2p of the CoMn / CN of Comparative Example 8 after etching surfThe signal peak intensities of Co2p and Mn2p decreased (Figures b and d). The above results indicate that the carbon nitride interlayer-confined CoMn dual-atom catalyst was successfully prepared.

[0075] Experimental Example 1

[0076] CoMn / CN of Example 1 inter CoMn / CN of Example 2 inter -1:0.5, CoMn / CN of Example 3 inter -1:1.5, CoMn / CN of Example 4 inter -NS, CoMn / CN of Example 5 inter -24h and CoMn / CN of Example 6 inter -36h, CoMn / CN of Example 7 inter -300 °C, CoMn / CN of Example 8 inter -400 °C, CN of Comparative Example 1, CN-1:1:1 of Comparative Example 2, CN-1:3:3 of Comparative Example 3, CN-450 °C of Comparative Example 4 and CN-650 °C of Comparative Example 5, Co / CN of Comparative Example 6 inter Mn / CN of Comparative Example 7 inter CoMn / CN of Comparative Example 8 surf Application of photo-Fenton-like for the removal of CBZ.

[0077] First, 2 mg of CoMn / CN prepared in Examples 1 to 8 and Comparative Examples 1 to 8 inter CoMn / CN inter -1:0.5, CoMn / CN inter -1:1.5, CoMn / CN inter -NS, CoMn / CN inter -24h, CoMn / CN inter -36h, CoMn / CN inter -300 °C, CoMn / CN inter -400 °C, CN, CN-1:1:1, CN-1:3:3, CN-450 °C, CN-650 °C, Co / CN inter Mn / CN inter and CoMn / CN surf were placed in 20 mL of 0.04 mM CBZ and stirred for 30 min in the dark to reach the adsorption-desorption equilibrium. Then, the reaction was excited by 0.0034 g of PMS and visible light. The visible light was provided by a 300.0 W xenon lamp (CEL-HXF300, Beijing Zhongjiao Jinyuan Co., Ltd.) with a filter having a wavelength less than 420 nm. The light intensity was 122.9 mW / cm 2 (Illumination area = 3.34 cm2 ) During the reaction, 2.0 mL of the sample was collected every 1 minute and filtered through a 0.22 μm filter membrane, and then 1 mM of Na 2 S 2 O 3 was added. The concentration of CBZ was determined by a Thermo Fisher liquid chromatograph.

[0078] Experimental Example 2

[0079] Application of CoMn / CN in Example 1 for the photo-Fenton-like removal of different organic pollutants. inter

[0080] First, 2 mg of CoMn / CN from Example 1 inter was placed in 20 mL of an aqueous solution containing 0.04 mM CBZ, sulfamethoxazole (SMX, 0.04 mM), bisphenol A (BPA, 0.04 mM), 4-chlorophenol (4-CP, 0.04 mM), and atrazine (ATZ, 0.04 mM). It was stirred in the dark for 30 min to reach the adsorption-desorption equilibrium. Then, the reaction was excited by 0.0034 g of PMS and visible light. The visible light was provided by a 300.0 W xenon lamp (CEL-HXF300, Beijing Zhongjiao Jinyuan Co., Ltd.) with a filter having a wavelength less than 420 nm. The light intensity was 122.9 mW / cm 2 (illumination area = 3.34 cm 2 ) During the reaction, 2.0 mL of the sample was collected every 1 minute and filtered through a 0.22 μm filter membrane, and then 1 mM of Na 2 S 2 O 3 was added. The concentrations of various organic pollutants were determined by a Thermo Fisher liquid chromatograph.

[0081] Experimental Example 3

[0082] Application of CoMn / CN in Example 1 for the stable photo-Fenton-like removal of CBZ. inter

[0083] First, 2 mg of CoMn / CN prepared in Example 1 and Comparative Examples 6 to 8 inter , CN, Co / CN inter Mn / CN inter CoMn / CN surf was placed in 20 mL of 0.04 mM CBZ. It was stirred in the dark for 30 min to reach the adsorption-desorption equilibrium. Then, the reaction was excited by 0.0034 g of PMS and visible light. The visible light was provided by a 300.0 W xenon lamp (CEL-HXF300, Beijing Zhongjiao Jinyuan Co., Ltd.) with a filter having a wavelength less than 420 nm. The light intensity was 122.9 mW / cm 2 (illumination area = 3.34 cm​​2 ) During the reaction, 2.0 mL of the sample was collected every 1 minute and filtered through a 0.22 μm filter membrane, and then 1 mM of Na 2 S 2 O 3 was added. After reacting for 5 minutes, the sample was centrifuged and dried for the next removal. This step was repeated 6 times. The concentration of CBZ was determined using a Thermo Fisher liquid chromatograph.

[0084] The efficiency and rate of photocatalytic Fenton removal of CBZ by CN in Comparative Example 1, CN-1:1:1 in Comparative Example 2, CN-1:3:3 in Comparative Example 3, CN-450 °C in Comparative Example 4, and CN-650 °C in Comparative Example 5 are as Figure 5 shown. The efficiency and rate constant of CBZ removal by CN in Comparative Example 1 were 17.73% and 0.0388 min −1 , respectively, which were higher than the efficiency and rate constants of CN-1:1:1, CN-1:3:3, CN-450 °C, and CN-650 °C in Comparative Examples 2-5.

[0085] CoMn / CN of Example 1 inter , CoMn / CN of Example 2 inter -1:0.5, CoMn / CN of Example 3 inter -1:1.5, CoMn / CN of Example 4 inter -NS, CoMn / CN of Example 5 inter -24 h, and CoMn / CN of Example 6 inter -36 h, CoMn / CN of Example 7 inter -300 °C, and CoMn / CN of Example 8 inter -400 °C for photocatalytic Fenton removal of CBZ efficiency and rate are as Figure 6 shown. The efficiency and rate constant of CBZ removal by CoMn / CN of Example 1 inter were 100% and 2.2513 min −1 , respectively, which were higher than those of CoMn / CN of Examples 2 to 8 inter -1:0.5, CoMn / CN inter -1:1.5, CoMn / CN inter -NS, CoMn / CN inter -24 h, and CoMn / CN inter -36 h, CoMn / CN inter -300 °C, and CoMn / CN inter -400 °C for CBZ removal efficiency and rate constants.

[0086] CoMn / CN of Example 7 inter, CN of Comparative Example 1, Co / CN of Comparative Example 6 inter , Mn / CN of Comparative Example 7 inter and CoMn / CN of Comparative Example 8 surf The efficiency and rate of photocatalytic Fenton for removing CBZ are as Figure 7 shown. The CoMn / CN of Example 1 inter The efficiency of photocatalytic Fenton degradation of CBZ within 5 min is 100%, which is higher than that of CN of Comparative Example 1 (17.7%), Co / CN of Comparative Example 6 inter (75.7%), Mn / CN of Comparative Example 7 inter (5.5%) and CoMn / CN of Comparative Example 8 surf (68.9%). The CoMn / CN of Example 1 inter The rate of photocatalytic Fenton degradation of CBZ is 2.2513 min −1 , which are 58.0, 3.9, 180.1 and 11.1 times that of CN of Comparative Example 1, Co / CN of Comparative Example 6 inter , Mn / CN of Comparative Example 7 inter and CoMn / CN of Comparative Example 8 surf respectively. The above results show that the CoMn / CN of Example 1 inter has excellent effect on removing CBZ.

[0087] The CoMn / CN of Example 1 inter and CoMn / CN of Comparative Example 8 surf The efficiency of removing CBZ in different systems is as Figure 8 shown. The CoMn / CN of Example 1 inter The degradation efficiency of carbamazepine in the photocatalytic Fenton system is 10.1% and 98.4% higher than that of CBZ degradation in the PMS-based Fenton-like system and the photocatalytic system respectively. However, the CoMn / CN of Comparative Example 8 surf The degradation efficiency of carbamazepine in the photocatalytic Fenton system is 31.4 and 66.9% higher than that of CBZ degradation in the PMS-based Fenton-like system and the photocatalytic system respectively. The above results prove the existence of confinement effect between the layers of two-dimensional carbon nitride.

[0088] The CoMn / CN of Example 1 inter and CoMn / CN of Comparative Example 4 surf The CBZ removal efficiency in the presence of different inorganic salts and humic acids is as Figure 9 shown. In the presence of inorganic salts such as NaCl, NaNO 3 and NaHCO 3 and humic acid (HA), the CoMn / CN of Example 1 interThe efficiency of removing CBZ is basically the same (~100.0%). CoMn / CN of Comparative Example 8 surf The efficiency of removing CBZ was significantly reduced to 19.0%, 29.4%, 9.1% and 21.8% respectively, indicating that CoMn / CN of Example 1 inter compared with CoMn / CN of Comparative Example 8 surf has excellent anti-interference performance.

[0089] CoMn / CN of Example 1 inter and CoMn / CN of Comparative Example 8 surf The efficiency of photo-Fenton degradation of different organic pollutants is as Figure 10 shown. The efficiency of CoMn / CN of Example 1 inter in removing typical pollutants CBZ, SMX, BPA, 4-CP and ATZ in different fields was 100.0%, 95.7%, 58.7%, 79.1% and 4.6% respectively. The efficiency of CoMn / CN of Comparative Example 8 surf in removing CBZ, SMX, BPA, 4-CP and ATZ was 68.9%, 81.3%, 5.3%, 1.0% and 1.0% respectively. Compared with CoMn / CN of Comparative Example 8 surf , CoMn / CN of Example 1 inter has higher reactivity and selectivity.

[0090] CoMn / CN of Example 1 inter The cyclic degradation efficiency and ion dissolution concentration are as Figure 11 shown. CoMn / CN of Example 1 inter After 6 cycles, the CBZ degradation rate only decreased from 2.2513 to 2.2260 min −1 , indicating that CoMn / CN of Example 1 inter has excellent stability. After 6 cycles, the ion dissolution concentrations of leached Mn and Co were 0.323 and 0.292 mg / L respectively, which are lower than the discharge standards of Mn (2.0 mg / L, GB8978-1996) and Co (1.0 mg / L, GB25467-2010).

[0091] CoMn / CN of Example 1 inter The XRD patterns and FT-IR results before and after are as Figure 12 shown. CoMn / CN of Example 1 inter The XRD and FT-IR signals basically did not change before and after the reaction, indicating that CoMn / CN of Example 1 inter has a stable phase structure and functional group structure.

[0092] As described above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention.

Claims

1. A carbon nitride-based cobalt-manganese diatomic catalyst with interlayer confinement effect, characterized in that: It includes carbon nitride having a two-dimensional layered structure, wherein Co and Mn atoms are intercalated between carbon nitride layers; The method for preparing the carbon nitride-based cobalt-manganese diatomic catalyst with interlayer confinement effect is characterized by comprising the following steps: The urea was calcined at 450-650°C for 2h, cooled to room temperature, washed alternately with ethanol and water, and then dried to prepare a carbon nitride precursor; The carbon nitride precursor, KCl and LiCl are fully ground and mixed, calcined at high temperature under a nitrogen atmosphere, cooled to room temperature, washed alternately with ethanol and water and then dried to prepare carbon nitride; the mass ratio of the carbon nitride precursor, KCl and LiCl is 1:1~3:1~3; Add ammonia water to the mixture of MnCl2 and CoCl2 to prepare CoMn-NH4 + Complex solution; the ratio of MnCl2 to CoCl2 is 1:0.5~1.5; CoMn-NH4 + The complex solution, carbon nitride and carboxymethyl cellulose were stirred at room temperature for 12-36 hours, washed alternately with ethanol and water, dried and fully ground, calcined at 300-400 °C in a nitrogen atmosphere for 2 hours and then cooled to room temperature at a heating rate of 5 °C / min; washed alternately with ethanol and water and dried to obtain CoMn / CN inter .

2. The carbon nitride-based cobalt-manganese diatomic catalyst with interlayer confinement effect as claimed in claim 1, characterized in that: The urea calcination temperature is 550°C.

3. The carbon nitride-based cobalt-manganese diatomic catalyst with interlayer confinement effect as claimed in claim 1, characterized in that: The mass ratio of KCl to LiCl is 1:

1.

4. The carbon nitride-based cobalt-manganese diatomic catalyst with interlayer confinement effect as claimed in claim 1, characterized in that: The mass ratio of the carbon nitride precursor, KCl and LiCl is 1:2:

2.

5. The carbon nitride-based cobalt-manganese diatomic catalyst with interlayer confinement effect as claimed in claim 1, characterized in that: The low-temperature calcination temperature is 350°C.

6. Use of the carbon nitride-based cobalt-manganese diatomic catalyst with interlayer confinement effect as claimed in claim 1 in the selective degradation of different organic pollutants.

7. The use according to claim 6, characterized in that: The organic pollutants include one or more of tetracycline hydrochloride, 4-chlorophenol, bisphenol A, atrazine, sulfamethoxazole and carbamazepine.

8. The use according to claim 7, characterized in that: The organic pollutant is carbamazepine.

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