HKUST-1 / g-c3n4 heterogeneous porous composite material, and preparation method and application thereof

Abstract

The application provides a kind of heterogeneous porous HKUST-1 / g-C3N4 composite material and its preparation method and application, belong to nanometer material science and technology field.The preparation method of the present application is to carry out first heat treatment to g-C3N4 precursor under air atmosphere, obtain g-C3N4 powder;After ultrasonic treatment of g-C3N4 powder, second heat treatment is carried out under air atmosphere to obtain g-C3N4 nanosheet;With water, ethanol and N, N-dimethylformamide as mixed solvent, g-C3N4 nanosheet, first copper salt and organic ligand are electrostatic self-assembly and hydrothermal reaction, to obtain HKUST-1 / g-C3N4 composite material;Disperse it in second copper salt solution, carry out third heat treatment under air atmosphere, to obtain heterogeneous porous HKUST-1 / g-C3N4 composite material.The material prepared by the present application has excellent catalytic performance without oxidant and light.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials science and technology, and more specifically to a heterogeneous porous HKUST-1 / g-C3N4 composite material, its preparation method, and its application. Background Technology

[0002] Advanced oxidation processes (AOPs) are a novel and effective method for removing organic pollutants from wastewater. However, most current AOPs require the addition of oxidants such as H₂O₂ or persulfate to achieve rapid degradation of pollutants, leading to increased costs and the potential for excessive oxidant residues that can harm human health. To better facilitate the practical application of AOPs technology, new solutions that are not constrained by the addition of external oxidants need to be explored.

[0003] Graphitic carbon nitride (g-C3N4) is a metal-free polymer semiconductor that has been reported as a novel visible-light-driven photocatalyst for hydrogen evolution and pollutant degradation due to its good thermochemical stability, electronic properties, optical characteristics, and suitable band gap (approximately 2.70 eV). Because of the selective two-electron reduction of oxygen, g-C3N4 is suitable for the self-activation of O2 to produce H2O2. While this emerging photocatalytic technology can utilize solar energy to achieve self-production of H2O2, the stability of the photocatalytic process cannot be guaranteed due to limitations imposed by light conditions. Furthermore, as a single-phase catalyst, g-C3N4 is limited by the high recombination rate of photoinduced electron-hole pairs, resulting in low quantum efficiency and low photocatalytic activity. Summary of the Invention

[0004] To address the above problems, this invention provides a heterogeneous porous HKUST-1 / g-C3N4 composite material, its preparation method, and its application. This invention combines the copper-based metal-organic framework material HKUST-1 with g-C3N4 to form a heterojunction, which improves the photocatalytic performance under light conditions. Furthermore, through decarboxylation treatment, the prepared product exhibits excellent molecular oxygen activation ability and excellent catalytic performance even without the need for oxidants and light.

[0005] The first objective of this invention is to provide a method for preparing heterogeneous porous HKUST-1 / g-C3N4 composite material, comprising the following steps:

[0006] Under air atmosphere, the g-C3N4 precursor was subjected to a first heat treatment at 500℃~520℃ to undergo a thermal polymerization reaction, and g-C3N4 powder was obtained.

[0007] g-C3N4 powder was exfoliated by ultrasonic treatment, and then subjected to a second heat treatment at 500℃~520℃ in air atmosphere to obtain g-C3N4 nanosheets.

[0008] Using water, ethanol and N,N-dimethylformamide as a mixed solvent, g-C3N4 nanosheets, the first copper salt and organic ligands were electrostatically self-assembled, and then subjected to a hydrothermal reaction at 80℃~100℃ to obtain HKUST-1 / g-C3N4 composite material.

[0009] The HKUST-1 / g-C3N4 composite material was dispersed in a second copper salt solution and stirred until homogeneous. Then, it was subjected to a third heat treatment at 150℃~200℃ in air atmosphere to obtain a heterogeneous porous HKUST-1 / g-C3N4 composite material.

[0010] In a preferred embodiment of the present invention, the mass ratio of g-C3N4 nanosheets, the first copper salt, and the organic ligand is 0.5~9:1~5:1; more preferably, the mass ratio of g-C3N4 nanosheets, the first copper salt, and the organic ligand is 1:2:1.

[0011] The volume ratio of water, ethanol and N,N-dimethylformamide is 1~4:1~5:2; more preferably, the volume ratio of water, ethanol and N,N-dimethylformamide is 1:1:2; the ratio of the first copper salt to the mixed solvent is 7mg~20mg:5mL.

[0012] In a preferred embodiment of the present invention, the hydrothermal reaction time is 9h to 13h.

[0013] In a preferred embodiment of the present invention, the amount of the second copper salt added is 5% to 50% of the mass of the HKUST-1 / g-C3N4 composite material.

[0014] In a preferred embodiment of the present invention, the processing time for the third heat treatment is 3h to 7h.

[0015] In a preferred embodiment of the present invention, the second heat treatment takes 1 to 5 hours, and the ultrasonic treatment takes 8 to 12 hours.

[0016] In a preferred embodiment of the present invention, the processing time for the first heat treatment is 3h to 8h.

[0017] In a preferred embodiment of the present invention, the first copper salt is copper nitrate, the organic ligand is 1,3,5-benzenetricarboxylic acid, and the second copper salt is copper nitrate.

[0018] The second objective of this invention is to provide a heterogeneous porous HKUST-1 / g-C3N4 composite material prepared by the above-described preparation method.

[0019] The third objective of this invention is to provide the application of the aforementioned heterogeneous porous HKUST-1 / g-C3N4 composite material in wastewater treatment. Specifically, wastewater treatment involves the efficient degradation of organic matter in wastewater; various antibiotics such as oxytetracycline, chlortetracycline, or tetracycline hydrochloride are used. Alternatively, it can involve the efficient elimination of bacteria in wastewater; various bacteria include cocci, bacilli, and spirilla, such as Staphylococcus, Escherichia coli, and Streptococcus pneumoniae.

[0020] More preferably, the heterogeneous porous HKUST-1 / g-C3N4 composite material provided by the present invention exhibits excellent degradation effect on tetracycline hydrochloride. Under visible light conditions, it achieves a 99.95% degradation rate of tetracycline hydrochloride in 20 minutes.

[0021] The heterogeneous porous HKUST-1 / g-C3N4 composite material of this invention possesses a typical heterojunction structure, which significantly reduces the photogenerated carrier recombination rate of g-C3N4 and improves photocatalytic performance. Compared to pure HKUST-1, the heterogeneous porous HKUST-1 / g-C3N4 composite material has a higher Cu(I) content, thereby enabling the material to achieve excellent molecular oxygen activation performance. The heterogeneous porous HKUST-1 / g-C3N4 composite material of this invention exhibits excellent performance in degrading organic pollutants in water, achieving efficient degradation under both dark and light conditions without the need for the addition of oxidants.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) In this invention, g-C3N4 powder is prepared by ultrasonic and heat treatment to obtain g-C3N4 nanosheets. g-C3N4 is negatively charged and the copper-based metal-organic framework material HKUST-1 is positively charged. The two are initially combined by electrostatic self-assembly and then further tightly combined by hydrothermal synthesis to prepare a heterojunction HKUST-1 / g-C3N4 composite material. Then, a heterogeneous porous structure is constructed in the copper-based metal-organic framework material by decarboxylation treatment, thereby preparing an HKUST-1 / g-C3N4 composite material with a heterogeneous porous structure. Combining the visible light response characteristics of g-C3N4 and the high efficiency of heterogeneous porous HKUST-1 to generate H2O2 by molecular oxygen activation, the organic pollutants in water are efficiently removed under both dark and light conditions. The heterogeneous porous HKUST-1 / g-C3N4 composite material of the present invention has a sponge-like heterogeneous pore structure. The newly formed mesoporous and macroporous structures promote the interaction between macromolecules and active sites in the HKUST-1 structure, further broadening the application of the heterogeneous porous HKUST-1 / g-C3N4 composite material in the fields of catalysis and macromolecular adsorption.

[0024] (2) The heterogeneous porous HKUST-1 / g-C3N4 composite material prepared in this invention is used in water treatment. No external oxidant is required in the process, and it has excellent catalytic performance under both dark and light conditions.

[0025] (3) The preparation method of the present invention is safe, low cost, and free from secondary pollution, and can be prepared in large quantities. Attached Figure Description

[0026] Figure 1 The image shows a SEM image of the HP-HKUST-1 / g-C3N4 composite material prepared in Example 1.

[0027] Figure 2 This is a SEM image of the HP-HKUST-1 / g-C3N4 composite material prepared in Example 2.

[0028] Figure 3 This is a SEM image of the HP-HKUST-1 / g-C3N4 composite material prepared in Example 3.

[0029] Figure 4 This is a SEM image of the HKUST-1 / g-C3N4 composite material prepared in Comparative Example 1.

[0030] Figure 5 The results are the results of the removal of antibiotic contaminants in water treatment using the HP-HKUST-1 / g-C3N4 composite material prepared in Example 1 and the HKUST-1 / g-C3N4 composite material prepared in Comparative Example 1.

[0031] Figure 6 The results are the test results of removing antibiotic pollutants in water treatment using the HP-HKUST-1 / g-C3N4 composite materials prepared in Examples 1, 2 and 3. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] This invention provides a method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material. In the preparation, HKUST-1, a copper-based metal-organic framework material with molecular oxygen activation potential, and g-C3N4, a material with visible light responsiveness, are selected as raw materials. An interfacial heterostructure is constructed between HKUST-1 and the nanosheet-like g-C3N4 material to improve the band structure of the composite material, further enhancing its photocatalytic performance under illumination. Furthermore, the pore structure and chemical structure of the material are modified through decarboxylation treatment, endowing it with excellent molecular oxygen activation ability, enabling it to achieve high antibiotic removal efficiency without oxidants or light irradiation. The heterogeneous porous HKUST-1 / g-C3N4 composite material prepared by this invention does not require external oxidants and exhibits excellent catalytic performance under both dark and light conditions. The specific preparation method is as follows:

[0034] Step 1: Under an air atmosphere, the g-C3N4 precursor is subjected to a first heat treatment at 500℃~520℃, and g-C3N4 powder is prepared by thermal polymerization.

[0035] Step 2: After ultrasonic treatment of g-C3N4 powder, a second heat treatment at 500℃~520℃ in air atmosphere is performed to obtain g-C3N4 nanosheets. In this step, ultrasonic exfoliation is first used for exfoliation, followed by a second heat treatment in a high-temperature furnace to further separate the g-C3N4 sheets. The resulting g-C3N4 nanosheets can better combine with HKUST-1 in subsequent steps through electrostatic self-assembly and hydrothermal synthesis to form a heterojunction interface. It should be noted that in this step, after ultrasonication and the second heat treatment, the g-C3N4 powder obtained in Step 1 is processed into g-C3N4 nanosheets with a diameter of 200nm~700nm and a thickness of 5nm~10nm. This size is also beneficial for improving the specific surface area and photogenerated carrier separation rate.

[0036] Step 3: Using water, ethanol and N,N-dimethylformamide as solvents, g-C3N4 nanosheets, metal salt and organic ligands are subjected to hydrothermal reaction at 80℃~90℃ to obtain HKUST-1 / g-C3N4 composite material.

[0037] Step 4: After dispersing the HKUST-1 / g-C3N4 composite material in a metal salt solution and stirring, a third heat treatment is performed at 160℃~180℃ in an air atmosphere. By decarboxylating the HKUST-1 / g-C3N4 composite material, the pore structure of HKUST-1 is changed, resulting in a sponge-like hierarchical porous structure in the prepared heterogeneous porous HKUST-1 / g-C3N4 composite material. This improves water stability, increases the number of active sites, and significantly increases the Cu(I) content, thereby greatly enhancing the molecular oxygen activation performance of the HKUST-1 / g-C3N4 composite material.

[0038] Example 1

[0039] (1) Melamine was placed in a corundum crucible and sealed tightly. It was placed in a tube furnace and heated to 500°C for 4 hours in an air atmosphere at a rate of 5°C / min. It was then cooled to room temperature at a rate of 3°C / min. The resulting block g-C3N4 was ground in a ceramic mortar to obtain g-C3N4 powder.

[0040] (2) Take 500 mg g-C3N4 powder and disperse it in 400 ml of deionized water. Sonicate at 240 W (40 Hz) for 12 h. Then centrifuge at 8000 r / min, dry, and place in a tube furnace. Heat it to 520 °C at a rate of 5 °C / min in air atmosphere for 2 h. Cool it to room temperature at a rate of 3 °C / min to obtain g-C3N4 nanosheets.

[0041] (3) Add 200 mg g-C3N4 nanosheets, 200 mg Cu(NO3)2 and 100 mg 1,3,5-benzenetricarboxylic acid to a 50 mL mixed solution of water, ethanol and DMF in a volume ratio of 1:1:2, sonicate for 1 h, stir at room temperature for 6 h to obtain the precursor solution of HKUST-1 / g-C3N4;

[0042] (4) Place the HKUST-1 / g-C3N4 precursor solution into a hydrothermal reactor with a polytetrafluoroethylene liner, place it in a vacuum drying oven and heat-treat at 85°C for 12 hours, then use 10 4 Centrifuge at r / min, wash with ethanol 3 times, dry to obtain HKUST-1 / g-C3N4 composite material powder;

[0043] (5) Add 200 mg HKUST-1 / g-C3N4 composite material powder and 30 mg Cu(NO3)2 to 50 mL of ethanol solution, sonicate for 1 h, stir for 12 h, dry in a vacuum drying oven, and then place in a tube furnace, heat to 200 °C at a rate of 5 °C / min in air atmosphere for 5 h, and cool to room temperature at a rate of 2 °C / min to obtain heterogeneous porous HKUST-1 / g-C3N4 composite material powder, denoted as HP-HKUST-1 / g-C3N4.

[0044] The prepared HP-HKUST-1 / g-C3N4 composite material has a sponge-like heterogeneous porous structure, such as Figure 1 As shown.

[0045] Example 2

[0046] (1) Melamine was placed in a corundum crucible and sealed tightly. It was placed in a tube furnace and heated to 500°C for 4 hours in an air atmosphere at a rate of 5°C / min. It was then cooled to room temperature at a rate of 3°C / min. The resulting block g-C3N4 was ground in a ceramic mortar to obtain g-C3N4 powder.

[0047] (2) Take 500 mg g-C3N4 powder and disperse it in 400 ml of deionized water. Sonicate at 240 W (40 Hz) for 12 h. Then centrifuge at 8000 r / min, dry, and place in a tube furnace. Heat it to 520 °C at a rate of 5 °C / min in air atmosphere for 2 h. Cool it to room temperature at a rate of 3 °C / min to obtain g-C3N4 nanosheets.

[0048] (3) Add 70 mg g-C3N4 nanosheets, 200 mg Cu(NO3)2 and 100 mg 1,3,5-benzenetricarboxylic acid to a 50 mL mixed solution of water, ethanol and DMF in a volume ratio of 1:1:2, sonicate for 1 h, stir at room temperature for 6 h to obtain the precursor solution of HKUST-1 / g-C3N4;

[0049] (4) Place the HKUST-1 / g-C3N4 precursor solution into a hydrothermal reactor with a polytetrafluoroethylene liner, place it in a vacuum drying oven and heat-treat at 85°C for 12 hours, then use 10 4 Centrifuge at r / min, wash with ethanol 3 times, dry to obtain HKUST-1 / g-C3N4 composite material powder;

[0050] (5) Add 200 mg HKUST-1 / g-C3N4 composite material powder and 30 mg Cu(NO3)2 to 50 mL of ethanol solution, sonicate for 1 h, stir for 12 h, dry in a vacuum drying oven, and then place in a tube furnace, heat to 200 °C at a rate of 5 °C / min in air atmosphere for 5 h, and cool to room temperature at a rate of 2 °C / min to obtain heterogeneous porous HKUST-1 / g-C3N4 composite material powder, denoted as HP-HKUST-1 / g-C3N4.

[0051] The prepared HP-HKUST-1 / g-C3N4 composite material is as follows: Figure 2 As shown.

[0052] Example 3

[0053] (1) Melamine was placed in a corundum crucible and sealed tightly. It was placed in a tube furnace and heated to 500°C for 4 hours in an air atmosphere at a rate of 5°C / min. It was then cooled to room temperature at a rate of 3°C / min. The resulting block g-C3N4 was ground in a ceramic mortar to obtain g-C3N4 powder.

[0054] (2) Take 500 mg g-C3N4 powder and disperse it in 400 ml of deionized water. Sonicate at 240 W (40 Hz) for 12 h. Then centrifuge at 8000 r / min, dry, and place in a tube furnace. Heat it to 520 °C at a rate of 5 °C / min in air atmosphere for 2 h. Cool it to room temperature at a rate of 3 °C / min to obtain g-C3N4 nanosheets.

[0055] (3) Add 200 mg g-C3N4 nanosheets, 70 mg Cu(NO3)2 and 34 mg 1,3,5-benzenetricarboxylic acid to a 50 mL mixed solution of water, ethanol and DMF in a volume ratio of 1:1:2, sonicate for 1 h and stir at room temperature for 6 h to obtain the precursor solution of HKUST-1 / g-C3N4.

[0056] (4) Place the HKUST-1 / g-C3N4 precursor solution into a hydrothermal reactor with a polytetrafluoroethylene liner, place it in a vacuum drying oven and heat-treat at 85°C for 12 hours, then use 10 4 Centrifuge at r / min, wash with ethanol 3 times, dry to obtain HKUST-1 / g-C3N4 composite material powder;

[0057] (5) Add 200 mg HKUST-1 / g-C3N4 composite material powder and 30 mg Cu(NO3)2 to 50 mL of ethanol solution, sonicate for 1 h, stir for 12 h, dry in a vacuum drying oven, and then place in a tube furnace, heat to 200 °C at a rate of 5 °C / min in air atmosphere for 5 h, and cool to room temperature at a rate of 2 °C / min to obtain HP-HKUST-1 / g-C3N4 composite material powder, denoted as HP-HKUST-1 / g-C3N4.

[0058] The prepared HP-HKUST-1 / g-C3N4 composite material is as follows: Figure 3 As shown.

[0059] Example 4

[0060] (1) Melamine was placed in a corundum crucible and sealed tightly. It was placed in a tube furnace and heated to 520°C for 3 hours in an air atmosphere at a rate of 5°C / min. It was then cooled to room temperature at a rate of 3°C / min. The resulting block g-C3N4 was ground in a ceramic mortar to obtain g-C3N4 powder.

[0061] (2) Take 500 mg g-C3N4 powder and disperse it in 400 ml of deionized water. Sonicate at 240 W (40 Hz) for 10 h, then centrifuge at 8000 r / min, dry, and then place in a tube furnace. Heat it to 520 °C at a rate of 5 °C / min in air atmosphere for 1 h, and then cool it to room temperature at a rate of 3 °C / min to obtain g-C3N4 nanosheets.

[0062] (3) Add 360 mg g-C3N4 nanosheets, 200 mg Cu(NO3)2 and 40 mg 1,3,5-benzenetricarboxylic acid to a 50 mL mixed solution of water, ethanol and DMF in a volume ratio of 4:5:2, sonicate for 1 h and stir at room temperature for 6 h to obtain the precursor solution of HKUST-1 / g-C3N4.

[0063] (4) Place the HKUST-1 / g-C3N4 precursor solution into a hydrothermal reactor with a polytetrafluoroethylene liner, place it in a vacuum drying oven and heat-treat at 80°C for 13 hours, then use 10 4 Centrifuge at r / min, wash with ethanol 3 times, dry to obtain HKUST-1 / g-C3N4 composite material powder;

[0064] (5) Add 200 mg HKUST-1 / g-C3N4 composite material powder and 100 mg Cu(NO3)2 to 50 mL of ethanol solution, sonicate for 1 h, stir for 6 h, dry in a vacuum drying oven, and then place in a tube furnace, heat to 150 °C at a rate of 5 °C / min in air atmosphere for 3 h, and cool to room temperature at a rate of 2 °C / min to obtain heterogeneous porous HKUST-1 / g-C3N4 composite material powder.

[0065] Example 5

[0066] (1) Melamine was placed in a corundum crucible and sealed tightly. It was placed in a tube furnace and heated to 510°C at a rate of 5°C / min for 8 hours in an air atmosphere. It was then cooled to room temperature at a rate of 3°C / min. The resulting block g-C3N4 was ground in a ceramic mortar to obtain g-C3N4 powder.

[0067] (2) Take 500 mg g-C3N4 powder and disperse it in 400 ml of deionized water. Sonicate at 240 W (40 Hz) for 8 h. Then centrifuge at 8000 r / min, dry, and place in a tube furnace. Heat it to 510 °C at a rate of 5 °C / min in air atmosphere for 5 h. Cool it to room temperature at a rate of 3 °C / min to obtain g-C3N4 nanosheets.

[0068] (3) Add 12.5 mg g-C3N4 nanosheets, 100 mg Cu(NO3)2 and 25 mg 1,3,5-benzenetricarboxylic acid to a 50 mL mixed solution of water, ethanol and DMF in a volume ratio of 3:2:2, sonicate for 1 h and stir at room temperature for 6 h to obtain the precursor solution of HKUST-1 / g-C3N4;

[0069] (4) Place the HKUST-1 / g-C3N4 precursor solution into a hydrothermal reactor with a polytetrafluoroethylene liner, place it in a vacuum drying oven and heat-treat at 100°C for 9 hours, then use 10 4 Centrifuge at r / min, wash with ethanol 3 times, dry to obtain HKUST-1 / g-C3N4 composite material powder;

[0070] (5) Add 200 mg HKUST-1 / g-C3N4 composite material powder and 10 mg Cu(NO3)2 to 50 mL of ethanol solution, sonicate for 1 h, stir for 10 h, dry in a vacuum drying oven, and then place in a tube furnace, heat-treat at 170 °C for 7 h in air atmosphere at a rate of 5 °C / min, and cool to room temperature at a rate of 2 °C / min to obtain heterogeneous porous HKUST-1 / g-C3N4 composite material powder.

[0071] Comparative Example 1

[0072] (1) Melamine was placed in a corundum crucible and sealed tightly. It was placed in a tube furnace and heated to 500°C for 4 hours in an air atmosphere at a rate of 5°C / min. It was then cooled to room temperature at a rate of 3°C / min. The resulting block g-C3N4 was ground in a ceramic mortar to obtain g-C3N4 powder.

[0073] (2) Take 500 mg g-C3N4 powder and disperse it in 400 ml of deionized water. Sonicate at 240 W (40 Hz) for 12 h. Then centrifuge at 8000 r / min, dry, and place in a tube furnace. Heat it to 520 °C at a rate of 5 °C / min in air atmosphere for 2 h. Cool it to room temperature at a rate of 3 °C / min to obtain g-C3N4 nanosheets.

[0074] (3) Add 200 mg g-C3N4 nanosheets, 200 mg Cu(NO3)2 and 100 mg 1,3,5-benzenetricarboxylic acid to a 50 mL mixed solution of water, ethanol and DMF in a volume ratio of 1:1:2, sonicate for 1 h, stir at room temperature for 6 h to obtain the precursor solution of HKUST-1 / g-C3N4;

[0075] (4) Place the HKUST-1 / g-C3N4 precursor solution into a hydrothermal reactor with a polytetrafluoroethylene liner, place it in a vacuum drying oven and heat-treat at 85°C for 12 hours, then use 10 4 Centrifuge at r / min, wash three times with ethanol, and dry to obtain HKUST-1 / g-C3N4 composite material powder.

[0076] The prepared HKUST-1 / g-C3N4 composite material does not possess a sponge-like heterogeneous porous structure, such as Figure 4 As shown.

[0077] Figures 1-3 The SEM images shown reveal that the HP-HKUST-1 / g-C3N4 composite materials prepared in Examples 1-3 all possess a sponge-like heterogeneous porous structure. Figure 4 The HKUST-1 / g-C3N4 composite material prepared in Comparative Example 1 did not form a heterogeneous porous structure. This indicates that the decarboxylation treatment applied in step 5 can construct a heterogeneous porous structure for the HKUST-1 / g-C3N4 composite material, which is beneficial to improving the ability of the HP-HKUST-1 / g-C3N4 composite material to treat macromolecular pollutants.

[0078] Antibiotic contaminant removal test in water treatment

[0079] (0) The degradation performance of heterogeneous porous HKUST-1 / g-C3N4 composite material for tetracycline hydrochloride (TCH) was studied in a dark environment. First, the degradation performance was investigated at an initial concentration of 50 mg·L⁻¹.-1 30 mg of the HP-HKUST-1 / g-C3N4 composite material prepared in Example 1 or 50 mg of the HKUST-1 / g-C3N4 composite material prepared in Comparative Example 1 was added to 50 mL of tetracycline hydrochloride solution. The solution was kept in the dark for 30 minutes with continuous stirring. During this period, 2.5 mL of solution was collected every 5 min at the designed time intervals, centrifuged, and the supernatant was collected. The absorbance of the TCH solution at the characteristic absorption wavelength (357 nm) was then measured using an ultra-micro spectrophotometer. All tests were repeated three times to ensure accuracy.

[0080] (1) The performance testing steps under visible light conditions are the same as those in the dark environment, except that an external light source (400<λ<780nm) is added.

[0081] The results are as follows Figure 5 As shown, under dark conditions, the heterogeneous porous HP-HKUST-1 / g-C3N4 composite material prepared in Example 1 achieved a TCH removal rate of 99.20% after 30 minutes, while the HKUST-1 / g-C3N4 composite material prepared in Comparative Example 1 only achieved a TCH removal rate of 17.36% after 30 minutes. The heterogeneous porous HP-HKUST-1 / g-C3N4 composite material prepared in Example 1 effectively improved the TCH removal rate. Under visible light conditions, the HP-HKUST-1 / g-C3N4 composite material achieved a TCH removal rate of 99.95% after 20 minutes, with the removal rate being more than 50% higher than that under dark conditions.

[0082] Figure 5 In the figure, C represents the absorbance of the antibiotic solution measured at different times, and C0 represents the absorbance of the antibiotic solution at the initial time.

[0083] Figure 6 At an initial concentration of 50 mg·L -1 20 mg of the HP-HKUST-1 / g-C3N4 composite material prepared in Examples 1-3 was added to 50 mL of tetracycline hydrochloride solution, kept in the dark for 30 minutes, and then irradiated under visible light for 30 minutes for testing. The results are shown in the figure. Compared with Example 1, Example 2 reduced the amount of g-C3N4 nanosheets added, and... Figure 6 The catalytic performance test graphs show a slight decrease in catalytic performance. Compared to Example 1, Example 3, after reducing the amount of copper salt and organic ligand added, showed a slight decrease in catalytic performance. Figure 6 The catalytic performance test results show a significant decrease in catalytic performance. This indicates that the HP-HKUST-1 / g-C3N4 composite material prepared in Example 1 possesses excellent catalytic performance.

[0084] The heterogeneous porous composite material prepared by this invention possesses excellent molecular oxygen activation ability, making it suitable for degrading pollutants under dark conditions. It can autonomously reduce dissolved O2 in water to H2O2 without external assistance, and combines this with Cu in the composite material system. 2+ / Cu + A Fenton-like reaction was carried out to achieve efficient degradation of antibiotic pollutants in a dark environment. Due to the formation of the heterojunction interface, photogenerated electrons on the g-C3N4 nanosheets can be transferred to HKUST-1, providing sufficient electrons for the reduction of O2 to produce H2O2 by the heterogeneous porous composite material. This results in higher catalytic performance of the heterogeneous porous HP-HKUST-1 / g-C3N4 composite material under illumination.

[0085] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0086] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material, characterized in that, Includes the following steps: Under air atmosphere, the g-C3N4 precursor was subjected to a first heat treatment at 500℃ ~520℃ to undergo a thermal polymerization reaction, resulting in g-C3N4 powder. g-C3N4 powder was exfoliated by ultrasonic treatment, and then subjected to a second heat treatment at 500℃~520℃ in air atmosphere to obtain g-C3N4 nanosheets. Using water, ethanol and N,N-dimethylformamide as a mixed solvent, g-C3N4 nanosheets, the first copper salt and organic ligands were electrostatically self-assembled, and then hydrothermal reaction was carried out at 80℃~100℃ to obtain HKUST-1 / g-C3N4 composite material. The HKUST-1 / g-C3N4 composite material was dispersed in a second copper salt solution and stirred evenly. Then, it was subjected to a third heat treatment at 150℃~200℃ in air atmosphere to achieve decarboxylation treatment and construct a heterogeneous porous structure, thus obtaining the heterogeneous porous HKUST-1 / g-C3N4 composite material. The heterogeneous porous HKUST-1 / g-C3N4 composite material exhibits a 99.95% degradation rate of tetracycline hydrochloride under visible light conditions for 20 minutes.

2. The method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 1, characterized in that, The mass ratio of g-C3N4 nanosheets, the first copper salt, and the organic ligand is 0.5~9:1~5:1; The volume ratio of water, ethanol, and N,N-dimethylformamide is 1~4:1~5:2; the ratio of the first copper salt to the mixed solvent is 7mg~20mg:5mL.

3. The method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 1, characterized in that, The hydrothermal reaction takes 9 to 13 hours.

4. The method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 1, characterized in that, The amount of the second copper salt added is 5% to 50% of the mass of the HKUST-1 / g-C3N4 composite material.

5. The method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 1, characterized in that, The third heat treatment takes 3 to 7 hours.

6. The method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 1, characterized in that, The second heat treatment takes 1 to 5 hours, and the ultrasonic treatment takes 8 to 12 hours.

7. The method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 1, characterized in that, The first heat treatment takes 3 to 8 hours.

8. The method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 1, characterized in that, The first copper salt is copper nitrate, and the organic ligand is 1,3,5-benzenetricarboxylic acid. The second copper salt is copper nitrate.

9. A heterogeneous porous HKUST-1 / g-C3N4 composite material prepared by the preparation method according to any one of claims 1-8.

10. The application of the heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 9 in wastewater treatment.

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