HKUST-1 / g-C3N4 heterogeneous porous composite material as well as preparation method and application thereof

Abstract

The invention provides a heterogeneous porous HKUST-1 / g-C3N4 composite material as well as a preparation method and application thereof, and belongs to the technical field of nanometer material science. The preparation method comprises the following steps: in an air atmosphere, carrying out first heat treatment on a g-C3N4 precursor to obtain g-C3N4 powder; performing ultrasonic treatment on the g-C3N4 powder, and performing secondary heat treatment in an air atmosphere to obtain g-C3N4 nanosheets; the preparation method comprises the following steps: taking water, ethanol and N, N-dimethylformamide as a mixed solvent, and carrying out electrostatic self-assembly and hydrothermal reaction on the g-C3N4 nanosheet, a first copper salt and an organic ligand to obtain an HKUST-1 / g-C3N4 composite material; and dispersing the HKUST-1 / g-C3N4 composite material in a second copper salt solution, and carrying out third heat treatment in an air atmosphere to obtain the heterogeneous porous HKUST-1 / g-C3N4 composite material. The prepared material has excellent catalytic performance under the condition that an oxidizing agent and illumination are not needed.

Description

Technical Field

[0001] The present invention relates to the field of nanomaterial science and technology, and more particularly to a heterogeneous porous HKUST-1 / g-C 3 N 4 composite material and its preparation method and application. Background Art

[0002] Advanced Oxidation Process (AOPs) is a new and effective method for removing organic pollutants in wastewater. However, most current AOPs require the addition of oxidants such as H 2 O 2 or peroxymonosulfate to achieve rapid degradation of pollutants, resulting in increased costs and the residual of excessive oxidants that are harmful to human health. In order to better apply AOPs technology in practice, new solutions that are not restricted by external oxidants need to be explored.

[0003] Graphitic carbon nitride (g-C 3 N 4 ) is a metal-free polymeric semiconductor. Due to its good thermochemical stability, electronic properties, optical characteristics, and suitable bandgap (about 2.70 eV), it has been reported as a new visible-light-driven photocatalyst for hydrogen evolution and pollutant degradation. Due to the selective two-electron reduction of oxygen, g-C 3 N 4 is suitable for self-activating O 2 to produce H 2 O 2 . Although this emerging photocatalytic technology can utilize solar energy to produce H 2 O 2 by itself, it is limited by the light conditions, and the stability of the photocatalytic process cannot be guaranteed. Moreover, as a single-phase catalyst, g-C 3 N 4 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] Aiming at the above problems, the present invention provides a heterogeneous porous HKUST-1 / g-C 3 N 4 composite material and its preparation method and application. The present invention combines the copper-based metal-organic framework material HKUST-1 with g-C 3 N 4The composite forms a heterojunction, improving the photocatalytic performance under light illumination conditions. And through decarboxylation treatment, the prepared product has excellent molecular oxygen activation ability and also has excellent catalytic performance without the need for an oxidant and light illumination.

[0005] The first object of the present invention is to provide a preparation method of a heterogeneous porous HKUST-1 / g-C 3 N 4 composite material, comprising the following steps: Under an air atmosphere, the g-C 3 N 4 precursor is subjected to a first heat treatment at 500°C to 520°C to undergo a thermal polymerization reaction, obtaining g-C 3 N 4 powder; After the g-C 3 N 4 powder is exfoliated by ultrasonic treatment, under an air atmosphere, it is subjected to a second heat treatment at 500°C to 520°C to obtain g-C 3 N 4 nanosheets; Using water, ethanol, and N,N-dimethylformamide as a mixed solvent, the g-C 3 N 4 nanosheets, a first copper salt, and an organic ligand are subjected to electrostatic self-assembly, and then a hydrothermal reaction is carried out at 80°C to 100°C to obtain HKUST-1 / g-C 3 N 4 composite material; The HKUST-1 / g-C 3 N 4 composite material is dispersed in a second copper salt solution, stirred evenly, and then under an air atmosphere, it is subjected to a third heat treatment at 150°C to 200°C to obtain a heterogeneous porous HKUST-1 / g-C 3 N 4 composite material.

[0006] In a preferred embodiment of the present invention, the mass ratio of the g-C 3 N 4 nanosheets, the first copper salt, and the organic ligand is 0.5 to 9:1 to 5:1; more preferably, the mass ratio of the g-C 3 N 4 nanosheets, the first copper salt, and the organic ligand is 1:2:1; The volume ratio of water, ethanol, and N,N-dimethylformamide is 1 to 4:1 to 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 7 mg to 20 mg:5 mL.

[0007] In a preferred embodiment of the present invention, the reaction time of the hydrothermal reaction is 9 h to 13 h.

[0008] In a preferred embodiment of the present invention, the addition amount of the second copper salt is 5% to 50% of the mass of the HKUST-1 / g-C 3 N 4 composite material.

[0009] In a preferred embodiment of the present invention, the treatment time of the third heat treatment is 3 h to 7 h.

[0010] In a preferred embodiment of the present invention, the treatment time of the second heat treatment is 1 h to 5 h, and the time of the ultrasonic treatment is 8 h to 12 h.

[0011] In a preferred embodiment of the present invention, the treatment time of the first heat treatment is 3 h to 8 h.

[0012] 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.

[0013] The second object of the present invention is to provide a heterogeneous porous HKUST-1 / g-C prepared by the above preparation method 3 N 4 composite material.

[0014] The third object of the present invention is to provide the application of the above heterogeneous porous HKUST-1 / g-C 3 N 4 composite material in sewage treatment. Specifically, the sewage treatment is the efficient degradation of organic matter in sewage; various antibiotics are oxytetracycline, chlortetracycline or tetracycline hydrochloride, etc. Or the efficient elimination of bacteria in sewage; various bacteria include three categories: cocci, bacilli and spirilla, such as Staphylococcus aureus, Escherichia coli, Streptococcus pneumoniae, etc.

[0015] More preferably, the heterogeneous porous HKUST-1 / g-C provided by the present invention 3 N 4 composite material has excellent degradation effect on tetracycline hydrochloride. Under visible light conditions, 99.95% of tetracycline hydrochloride is achieved in 20 min.

[0016] The heterogeneous porous HKUST-1 / g-C of the present invention 3 N 4 composite material has a typical heterojunction structure, which can significantly reduce the recombination rate of photogenerated carriers of g-C 3 N 4 and improve the photocatalytic performance. Compared with pure HKUST-1, the heterogeneous porous HKUST-1 / g-C 3 N4 The composite material has a high Cu(I) content, enabling the material to obtain excellent molecular oxygen activation performance. The heterogeneous porous HKUST-1 / g-C of the present invention 3 N 4 The composite material has excellent performance in degrading organic pollutants in water, can achieve efficient degradation under both dark and light conditions, and does not require the addition of oxidants.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) In the present invention, the prepared g-C 3 N 4 powder is obtained by ultrasonic treatment and heat treatment to obtain g-C 3 N 4 nanosheets. g-C 3 N 4 is negatively charged, and the prepared 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 the HKUST-1 / g-C 3 N 4 composite material with a heterojunction. Then, a heterogeneous porous structure is constructed in the copper-based metal-organic framework material through decarboxylation treatment, thereby preparing a HKUST-1 / g-C 3 N 4 composite material with a heterogeneous pore structure. Combining the visible light response characteristics of g-C 3 N 4 and the high-efficiency molecular oxygen activation to produce H 2 O 2 of the heterogeneous porous HKUST-1 enables efficient removal of organic pollutants in water under both dark and light conditions. The heterogeneous porous HKUST-1 / g-C 3 N 4 composite material of the present invention has a sponge-like heterogeneous pore structure. The newly formed mesopores and macropores promote the interaction between macromolecules and the active sites in the HKUST-1 structure, further broadening the application of the heterogeneous porous HKUST-1 / g-C 3 N 4 composite material in the fields of catalysis and macromolecule adsorption.

[0018] (2) The application of the heterogeneous porous HKUST-1 / g-C 3 N 4 composite material prepared in the present invention in water treatment does not require an external oxidant and has excellent catalytic performance under both dark and light conditions.

[0019] (3) The preparation method of the present invention is safe, low in cost, free of secondary pollution, and can be prepared in large quantities. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 SEM image of the HP-HKUST-1 / g-C 3 N 4 composite material prepared in Example 1.

[0021] Figure 2 SEM image of the HP-HKUST-1 / g-C 3 N 4 composite material prepared in Example 2.

[0022] Figure 3 SEM image of the HP-HKUST-1 / g-C 3 N 4 composite material prepared in Example 3.

[0023] Figure 4 SEM image of the HKUST-1 / g-C 3 N 4 composite material prepared in Comparative Example 1.

[0024] Figure 5 Test results of the removal of antibiotic pollutants in water treatment using the HP-HKUST-1 / g-C 3 N 4 composite material prepared in Example 1 and the HKUST-1 / g-C 3 N 4 composite material prepared in Comparative Example 1.

[0025] Figure 6 Test results of the removal of antibiotic pollutants in water treatment using the HP-HKUST-1 / g-C 3 N 4 composite materials prepared in Example 1, Example 2, and Example 3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] The present invention provides a heterogeneous porous HKUST-1 / g-C 3 N 4Preparation method of composite material. During preparation, copper-based metal-organic framework material HKUST-1 with potential for molecular oxygen activation and g-C 3 N 4 material with visible light response ability are selected as raw materials to construct an interface heterojunction between HKUST-1 and nano-sheet g-C 3 N 4 material to improve the energy band structure of the composite material and further enhance the photocatalytic performance of the material under light illumination conditions; and the pore structure and chemical structure of the material are modified through decarboxylation treatment to endow it with excellent molecular oxygen activation ability, enabling it to have a high antibiotic removal efficiency without the need for an oxidant and light illumination; the heterogeneous porous HKUST-1 / g-C 3 N 4 composite material prepared by the present invention does not require an external oxidant and has excellent catalytic performance under both dark and light illumination conditions. The preparation is specifically carried out as follows:

[0028] Step 1: Under an air atmosphere, the g-C 3 N 4 precursor is subjected to a first heat treatment at 500 °C to 520 °C, and g-C 3 N 4 powder is prepared by a thermal polymerization method; Step 2: After subjecting the g-C 3 N 4 powder to ultrasonic treatment, it is subjected to a second heat treatment at 500 °C to 520 °C under an air atmosphere to obtain g-C 3 N 4 nano-sheets; during the preparation of this step, first, an ultrasonic exfoliation treatment method is used for exfoliation, and a second heat treatment is also carried out in a high-temperature furnace to cause further separation between the g-C 3 N 4 layers, and the resulting g-C 3 N 4 nano-sheets can be better combined with HKUST-1 through electrostatic self-assembly and hydrothermal synthesis in subsequent steps to form a heterojunction interface; it should be noted that after ultrasonic treatment and the second heat treatment in this step, the g-C 3 N 4 powder obtained in Step 1 is processed into g-C 3 N 4 nano-sheets with a sheet diameter of 200 nm to 700 nm and a thickness of 5 nm to 10 nm. Such dimensions are also beneficial for improving the specific surface area and the separation rate of photo-generated carriers.

[0029] Step 3: Using water, ethanol, and N,N-dimethylformamide as solvents, g-C 3 N 4The nanosheets, metal salt, and organic ligand are subjected to a hydrothermal reaction at 80 °C to 90 °C to obtain the HKUST-1 / g-C 3 N 4 composite material; Step 4: Disperse the HKUST-1 / g-C 3 N 4 composite material in a metal salt solution, stir, and then conduct a third heat treatment at 160 °C to 180 °C under an air atmosphere. By performing a decarboxylation treatment on the HKUST-1 / g-C 3 N 4 composite material, the pore structure of HKUST-1 is changed, so that the prepared heterogeneous porous HKUST-1 / g-C 3 N 4 composite material forms a sponge-like hierarchical porous structure, with improved water stability, increased active sites, and a significant increase in the Cu(I) content, thereby greatly enhancing the molecular oxygen activation performance of the HKUST-1 / g-C 3 N 4 composite material.

[0030] Example 1 (1) Put melamine into a corundum crucible, cover it tightly, place it in a tube furnace, and heat it to 500 °C at a rate of 5 °C / min in an air atmosphere for 4 h, and then cool it to room temperature at a rate of 3 °C / min to obtain the bulk g-C 3 N 4 and grind it in a ceramic mortar to obtain g-C 3 N 4 powder; (2) Take 500 mg of g-C 3 N 4 powder, disperse it in 400 ml of deionized water, ultrasonically treat it at 240 W (40 Hz) for 12 h, then centrifuge it at 8000 r / min, dry it, and then place it in a tube furnace. Heat it to 520 °C at a rate of 5 °C / min in an air atmosphere for 2 h, and then cool it to room temperature at a rate of 3 °C / min to obtain g-C 3 N 4 nanosheets; (3) Add 200 mg of g-C 3 N 4 nanosheets, 200 mg of Cu(NO 3 ) 2 and 100 mg of 1,3,5-benzenetricarboxylic acid to a 50 mL mixed solution of water, ethanol, and DMF with a volume ratio of 1:1:2, ultrasonically treat it for 1 h, and stir it at room temperature for 6 h to obtain the precursor solution of HKUST-1 / g-C 3 N 4 ; (4) Put the precursor solution of HKUST-1 / g-C 3 N 4 into a hydrothermal reactor with a PTFE inner liner, place it in a vacuum drying oven for heat treatment at 85 °C for 12 h, then centrifuge at 10 4 r / min, wash with ethanol 3 times, and dry to obtain HKUST-1 / g-C 3 N 4 composite powder; (5) Add 200 mg of HKUST-1 / g-C 3 N 4 composite powder and 30 mg of Cu(NO 3 ) 2 to 50 mL of ethanol solution, ultrasonicate for 1 h, stir for 12 h, place it in a vacuum drying oven to dry, then place it in a tubular furnace, heat it to 200 °C at a rate of 5 °C / min in an air atmosphere for heat treatment for 5 h, and cool it to room temperature at a rate of 2 °C / min to obtain heterogeneous porous HKUST-1 / g-C 3 N 4 composite powder, denoted as HP-HKUST-1 / g-C 3 N 4 .

[0031] The prepared HP-HKUST-1 / g-C 3 N 4 composite has a sponge-like heterogeneous pore structure, as Figure 1 shown.

[0032] Example 2 (1) Put melamine into a corundum crucible, cover it tightly, place it in a tubular furnace, heat it to 500 °C at a rate of 5 °C / min in an air atmosphere for heat treatment for 4 h, and cool it to room temperature at a rate of 3 °C / min to obtain the obtained bulk g-C 3 N 4 Grind it in a ceramic mortar to obtain g-C 3 N 4 powder; (2) Take 500 mg of g-C 3 N 4 powder, disperse it in 400 ml of deionized water, ultrasonicate it at 240 W (40 Hz) for 12 h, then centrifuge at 8000 r / min, dry it, and then place it in a tubular furnace, heat it to 520 °C at a rate of 5 °C / min in an air atmosphere for heat treatment for 2 h, and cool it to room temperature at a rate of 3 °C / min to obtain g-C 3 N 4 nanosheets; (3) Add 70 mg of g-C to a 50 mL mixed solution of water, ethanol and DMF with a volume ratio of 1:1:23 N 4 nanosheets, 200 mg of Cu(NO 3 ) 2 and 100 mg of 1,3,5-benzenetricarboxylic acid were ultrasonically treated for 1 h and stirred at room temperature for 6 h to obtain a precursor solution of HKUST-1 / g-C 3 N 4 ; (4)The precursor solution of HKUST-1 / g-C 3 N 4 was placed in a hydrothermal kettle with a polytetrafluoroethylene inner liner, placed in a vacuum drying oven and heat-treated at 85 °C for 12 h, then centrifuged at 10 4 r / min, washed 3 times with ethanol, and dried to obtain HKUST-1 / g-C 3 N 4 composite powder; (5)200 mg of HKUST-1 / g-C 3 N 4 composite powder and 30 mg of Cu(NO 3 ) 2 were added to 50 mL of ethanol solution, ultrasonically treated for 1 h, stirred for 12 h, placed in a vacuum drying oven and dried, then placed in a tube furnace, heated to 200 °C at a rate of 5 °C / min in an air atmosphere and heat-treated for 5 h, and cooled to room temperature at a rate of 2 °C / min to obtain heterogeneous porous HKUST-1 / g-C 3 N 4 composite powder, denoted as HP-HKUST-1 / g-C 3 N 4 .

[0033] The prepared HP-HKUST-1 / g-C 3 N 4 composite is as Figure 2 shown.

[0034] Example 3 (1)Melamine was placed in a corundum crucible, covered tightly, placed in a tube furnace, heated to 500 °C at a rate of 5 °C / min in an air atmosphere and heat-treated for 4 h, and cooled to room temperature at a rate of 3 °C / min to obtain the obtained bulk g-C 3 N 4 which was ground in a ceramic mortar to obtain g-C 3 N 4 powder; (2)Take 500 mg of g-C 3 N 4The powder was dispersed in 400 ml of deionized water and sonicated for 12 h at 240 W (40 Hz), then centrifuged at 8000 r / min, dried, and placed in a tube furnace. It was heated to 520 °C at a rate of 5 °C / min in an air atmosphere for heat treatment for 2 h, and then cooled to room temperature at a rate of 3 °C / min to obtain g-C 3 N 4 nanosheets; (3) 200 mg of g-C 3 N 4 nanosheets, 70 mg of Cu(NO 3 ) 2 and 34 mg of 1,3,5-benzenetricarboxylic acid were added to a 50 mL mixed solution of water, ethanol and DMF with a volume ratio of 1:1:2, sonicated for 1 h, and stirred at room temperature for 6 h to obtain the precursor solution of HKUST-1 / g-C 3 N 4 ; (4) The precursor solution of HKUST-1 / g-C 3 N 4 was placed in a hydrothermal autoclave with a polytetrafluoroethylene inner liner, placed in a vacuum drying oven for heat treatment at 85 °C for 12 h, then centrifuged at 10 4 r / min, washed 3 times with ethanol, dried to obtain the composite powder of HKUST-1 / g-C 3 N 4 ; (5) 200 mg of the composite powder of HKUST-1 / g-C 3 N 4 and 30 mg of Cu(NO 3 ) 2 were added to 50 mL of ethanol solution, sonicated for 1 h, stirred for 12 h, placed in a vacuum drying oven to dry, and then placed in a tube furnace. It was heated to 200 °C at a rate of 5 °C / min in an air atmosphere for heat treatment for 5 h, and cooled to room temperature at a rate of 2 °C / min to obtain the composite powder of HP-HKUST-1 / g-C 3 N 4 , denoted as HP-HKUST-1 / g-C 3 N 4 .

[0035] The prepared HP-HKUST-1 / g-C 3 N 4 composite material is as Figure 3 shown.

[0036] Example 4 (1) Melamine was placed in a corundum crucible with a tightly closed lid, placed in a tube furnace, heated to 520°C at a rate of 5°C / min in an air atmosphere for 3 h, and cooled to room temperature at a rate of 3°C / min. The resulting block gC 3 N 4 Grind in a ceramic mortar to obtain gC 3 N 4 powder; (2) Take 500 mg gC 3 N 4 The powder was dispersed in 400 ml of deionized water, ultrasonically treated at 240 W (40 Hz) for 10 h, then centrifuged at 8000 r / min, dried, and then placed in a tube furnace and heated to 520 °C at a rate of 5 °C / min in an air atmosphere for 1 h, and cooled to room temperature at a rate of 3 °C / min to obtain gC 3 N 4 Nanosheets; (3) Add 360 mg gC to 50 mL of a mixed solution of water, ethanol, and DMF in a volume ratio of 4:5:2. 3 N 4 Nanosheets, 200mg Cu(NO 3 ) 2 and 40 mg 1,3,5-benzenetricarboxylic acid, ultrasonicated for 1 h, stirred at room temperature for 6 h, and HKUST-1 / gC was obtained. 3 N 4 A precursor solution; (4) HKUST-1 / gC 3 N 4 The precursor solution was placed in a hydrothermal autoclave with a polytetrafluoroethylene liner, placed in a vacuum drying oven and heat treated at 80 °C for 13 h, and then 4 r / min centrifugation, washed with ethanol three times, and dried to obtain HKUST-1 / gC 3 N 4 Composite powders; (5) Add 200 mg HKUST-1 / gC to 50 mL of ethanol solution. 3 N 4 Composite powder and 100 mg Cu(NO 3 ) 2 , ultrasonic for 1 h, stirred for 6 h, placed in a vacuum drying oven for drying, then placed in a tube furnace, heated to 150 °C at a rate of 5 °C / min in air atmosphere for 3 h, and cooled to room temperature at a rate of 2 °C / min to obtain the heterogeneous porous HKUST-1 / gC 3 N 4 Composite powder.

[0037] Example 5 (1) Put melamine into a corundum crucible, cover it tightly, place it in a tube furnace, heat it to 510 °C at a rate of 5 °C / min in an air atmosphere for 8 h, and cool it to room temperature at a rate of 3 °C / min to obtain massive g-C 3 N 4 Grind it in a ceramic mortar to obtain g-C 3 N 4 powder; (2) Take 500 mg of g-C 3 N 4 powder, disperse it in 400 ml of deionized water, ultrasonically treat it at 240 W (40 Hz) for 8 h, then centrifuge it at 8000 r / min, dry it, and then place it in a tube furnace. Heat it to 510 °C at a rate of 5 °C / min in an air atmosphere for 5 h, and cool it to room temperature at a rate of 3 °C / min to obtain g-C 3 N 4 nanosheets; (3) Add 12.5 mg of g-C 3 N 4 nanosheets, 100 mg of Cu(NO 3 ) 2 and 25 mg of 1,3,5-benzenetricarboxylic acid to a 50 mL mixed solution of water, ethanol and DMF with a volume ratio of 3:2:2, ultrasonically treat it for 1 h, and stir it at room temperature for 6 h to obtain the precursor solution of HKUST-1 / g-C 3 N 4 ; (4) Put the precursor solution of HKUST-1 / g-C 3 N 4 into a hydrothermal kettle with a polytetrafluoroethylene inner liner, place it in a vacuum drying oven and heat it at 100 °C for 9 h, then centrifuge it at 10 4 r / min, wash it 3 times with ethanol, dry it to obtain the composite powder of HKUST-1 / g-C 3 N 4 ; (5) Add 200 mg of the composite powder of HKUST-1 / g-C 3 N 4 and 10 mg of Cu(NO 3 ) 2 to a 50 mL ethanol solution, ultrasonically treat it for 1 h, stir it for 10 h, place it in a vacuum drying oven to dry it, and then place it in a tube furnace. Heat it to 170 °C at a rate of 5 °C / min in an air atmosphere for 7 h, and cool it to room temperature at a rate of 2 °C / min to obtain the heterogeneous porous HKUST-1 / g-C 3 N 4 composite powder.

[0038] Comparative Example 1 (1) Melamine was placed in a corundum crucible and covered tightly, then placed in a tubular furnace. It was heated to 500 °C at a rate of 5 °C / min in an air atmosphere and heat-treated for 4 h, and then cooled to room temperature at a rate of 3 °C / min to obtain blocky g-C 3 N 4 which was ground in a ceramic mortar to obtain g-C 3 N 4 powder; (2) 500 mg of g-C 3 N 4 powder was dispersed in 400 ml of deionized water, ultrasonically treated at 240 W (40 Hz) for 12 h, then centrifuged at 8000 r / min, dried, and then placed in a tubular furnace. It was heated to 520 °C at a rate of 5 °C / min in an air atmosphere and heat-treated for 2 h, and then cooled to room temperature at a rate of 3 °C / min to obtain g-C 3 N 4 nanosheets; (3) 200 mg of g-C 3 N 4 nanosheets, 200 mg of Cu(NO 3 ) 2 and 100 mg of 1,3,5-benzenetricarboxylic acid were added to a 50 mL mixed solution of water, ethanol and DMF with a volume ratio of 1:1:2, ultrasonically treated for 1 h, and stirred at room temperature for 6 h to obtain a precursor solution of HKUST-1 / g-C 3 N 4 ; (4) The precursor solution of HKUST-1 / g-C 3 N 4 was placed in a hydrothermal kettle with a polytetrafluoroethylene inner liner, placed in a vacuum drying oven and heat-treated at 85 °C for 12 h, then centrifuged at 10 4 r / min, washed 3 times with ethanol, and dried to obtain HKUST-1 / g-C 3 N 4 composite powder.

[0039] The prepared HKUST-1 / g-C 3 N 4 composite does not have a spongy heterogeneous pore structure, as Figure 4 shown.

[0040] Figures 1 to 3 As can be observed from the SEM images shown in 3 3 N 4 Examples 1 to 3, the HP-HKUST-1 / g-C Figure 4The HKUST-1 / g-C prepared in Comparative Example 1 shown in 3 N 4 The composite material did not form a heterogeneous pore structure. It shows that the decarboxylation treatment applied in Step 5 can provide HKUST-1 / g-C 3 N 4 The composite material constructs a heterogeneous pore structure, which is beneficial to improving the treatment ability of HP-HKUST-1 / g-C 3 N 4 composite material for macromolecular pollutants.

[0041] Removal test of antibiotic pollutants in water treatment (0) The performance of heterogeneous porous HKUST-1 / g-C 3 N 4 composite material in degrading tetracycline hydrochloride (TCH) was studied in the dark environment. First, 30 mg of the HP-HKUST-1 / g-C -1 prepared in Example 1 was added to 50 mL of tetracycline hydrochloride solution with an initial concentration of 50 mg·L 3 N 4 composite material or 50 mg of the HKUST-1 / g-C 3 N 4 composite material prepared in Comparative Example 1. It was kept in the dark environment for 30 minutes and continuously stirred. During this period, 2.5 mL of the solution was collected every 5 minutes at the designed time intervals, centrifuged using a centrifuge, and the supernatant was taken. Then, the absorbance of the TCH solution at the characteristic absorption wavelength (357 nm) was detected using an ultra-micro spectrophotometer. All the tests were repeated three times to ensure accuracy;

[0042] (1) The performance test procedure under visible light conditions was the same as that in the dark environment, only adding an external light source (400 < λ < 780 nm).

[0043] The results are as Figure 5 shown. Under dark conditions, the removal rate of TCH by the heterogeneous porous HP-HKUST-1 / g-C 3 N 4 composite material prepared in Example 1 reached 99.20% in 30 minutes, while the removal rate of TCH by the HKUST-1 / g-C 3 N 4 composite material prepared in Comparative Example 1 was only 17.36% in 30 minutes. The heterogeneous porous HP-HKUST-1 / g-C 3 N 4 composite material prepared in Example 1 effectively improved the removal rate of TCH; under visible light conditions, HP-HKUST-1 / g-C 3 N 4The removal rate of TCH by the composite material reached 99.95% in 20 min, and the removal rate was increased by more than 50% compared with the dark condition.

[0044] Figure 5 Among them, C is the absorbance of the antibiotic solution measured at different times, and C 0 is the absorbance of the antibiotic solution at the initial moment.

[0045] Figure 6 was in 50 mL of tetracycline hydrochloride solution with an initial concentration of 50 mg·L -1 and 20 mg of the HP-HKUST-1 / g-C prepared in Examples 1 to 3 was added respectively. 3 N 4 composite material was kept in the dark environment for 30 minutes, and then irradiated under visible light for 30 min for the test result graph. Compared with Example 1, after reducing the addition amount of g-C 3 N 4 nanosheets in Example 2, it can be seen from the Figure 6 catalytic performance test graph that the catalytic performance decreased slightly. Compared with Example 1, after reducing the addition amounts of copper salt and organic ligand in Example 3, it can be seen from the Figure 6 catalytic performance test graph that the catalytic performance decreased significantly. It shows that the HP-HKUST-1 / g-C 3 N 4 composite material prepared in Example 1 has excellent catalytic performance.

[0046] The heterogeneous porous composite material prepared by the present invention has excellent molecular oxygen activation ability and is suitable for degrading pollutants under dark conditions. It can autonomously reduce the dissolved O 2 in water to H 2 O 2 without external conditions assistance, and combine with Cu 2+ / Cu + in the composite material system to carry out the Fenton-like reaction to achieve efficient degradation of antibiotic pollutants in the dark environment. Due to the formation of the heterojunction interface, the photogenerated electrons on the g-C 3 N 4 nanosheets can be transferred to HKUST-1, providing sufficient electrons for the process of the heterogeneous porous composite material to reduce O 2 to produce H 2 O 2 . This enables the heterogeneous porous HP-HKUST-1 / g-C 3 N 4 composite material to achieve higher catalytic performance under light irradiation.

[0047] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made by those skilled in the art once they learn of the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present invention.

[0048] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material, characterized in that: The following steps are involved: In an air atmosphere, the g-C3N4 precursor is subjected to a first heat treatment at 500°C to 520°C to undergo a thermal polymerization reaction to obtain a g-C3N4 powder; After the g-C3N4 powder was exfoliated by ultrasonic treatment, a second heat treatment was performed at 500°C to 520°C in an 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 the organic ligand were electrostatically self-assembled, and then hydrothermally reacted at 80℃~100℃ to obtain the HKUST-1 / g-C3N4 composite material; The HKUST-1 / g-C3N4 composite material is dispersed in the second copper salt solution and stirred evenly, and then subjected to a third heat treatment at 150°C~200°C in an air atmosphere to achieve decarboxylation treatment to construct a heterogeneous pore structure, thereby obtaining a heterogeneous porous HKUST-1 / g-C3N4 composite material.

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 7 mg-20 mg:5 mL.

3. The method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 1, characterized in that: The reaction time of the hydrothermal reaction is 9h~13h.

4. The method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 1, characterized in that: The addition amount of the second copper salt is 5%~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 treatment time of the third heat treatment is 3h~7h.

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

7. The method for preparing a heterogeneous porous HKUST-1 / g-C3N4 composite material according to claim 1, characterized in that: The treatment time of the first heat treatment is 3h~8h.

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

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

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