Ternary composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of organic pollutant degradation, in particular to a ternary composite material as well as a preparation method and application thereof. MTi powder and P-C3N5 are dissolved in an alcohol reagent for stirring reaction, the alcohol reagent is removed, and drying is conducted; and mixing a PDINH solution with the MIL-125 (Ti)-NH2 / P-C3N5 heterojunction and water, standing, and sequentially filtering and drying the obtained standing substance to obtain the ternary composite material. The method has the advantages of small reagent pollution, good reaction repeatability, mild preparation conditions and the like, by optimizing the material structure and widening the light absorption range, a good degradation effect is shown in the process of photocatalytic degradation of methylene blue and cefotaxime sodium, and the photocatalytic performance is stable.

Description

Technical Field

[0001] The present invention relates to the technical field of organic pollutant degradation, and particularly to a ternary composite material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of industrialization and urbanization, the problem of water pollution has become increasingly serious. In particular, the presence of refractory organic pollutants poses a great threat to the ecological environment and human health. Methylene blue and cefotaxime sodium, as common organic pollutants, are difficult to degrade spontaneously in the natural environment and have become urgent water pollution problems to be solved. As a green and efficient pollution treatment technology, photocatalytic technology has shown great potential in degrading organic pollutants. However, traditional photocatalytic materials have the problem of narrow light absorption range, which limits their efficiency in practical applications.

[0003] In recent years, the achievements in using photocatalytic technology to degrade water pollution have mainly focused on TiO 2 photocatalytic technology. However, TiO 2 has a wide bandgap and can only absorb ultraviolet light. Therefore, its light absorption band is narrow and it is not easy to improve the light utilization efficiency. The efficient catalysis of photocatalytic technology depends on the number of active sites of the catalyst and the minimization of charge recombination. Previously, the main research was on the organic semiconductor photocatalyst PDINH, which has been widely used in the field of photocatalysis because of its strong light absorption range, high fluorescence quantum efficiency, stable structure, excellent optoelectronic properties, and the ability to design and regulate its molecular structure. However, the shortcoming of poor activity of PDINH limits the use of this technology. By constructing heterojunctions and element doping, more photogenerated electrons and holes can be generated and the charge transfer efficiency can be enhanced, significantly improving the photocatalytic performance.

[0004] Synthesizing a novel nitrogen-rich carbon nitride (g-C 3 N 5 ) with stronger light absorption ability (>600 nm) from different groups using different precursors provides a feasible way to prepare efficient two-dimensional photocatalysts and may be widely used in the fields of energy production and environmental applications. The g-C 3 N 5 doped with phosphorus is particularly prominent. Among them, phosphorus is substituted for carbon sites to form P-N / P=N bonds, enhancing light absorption and reducing charge separation. Therefore, compared with the undoped g-C 3 N 5 sample, the P-doped g-C 3 N 5 has a higher PEC current density and higher photocatalytic efficiency in the degradation of rhodamine B dye or tetracycline under light irradiation, indicating its great potential in the efficient degradation of organic pollutants such as methylene blue and cefotaxime sodium.

[0005] Metal-Organic Framework (MOF) is a new type of crystalline material with a periodic network framework formed by organic ligands and metal ions. As a new type of photocatalyst, MOF has a high porosity, an adjustable porous structure, and similar semiconductor properties. In the photocatalytic reaction, due to the short transport distance of carriers to the hole surface in the whole structure, the high porosity of MOF is conducive to the separation of electrons and holes. Semiconductor MOF is very promising to combine with C 3 N 5 to form a heterojunction for promoting photocatalytic hydrogen evolution, because the porous structure of MOF endows the heterojunction with effective diffusion of the substrate. Constructing a heterojunction through MOF and other semiconductors is an ideal modification method.

[0006] During the photocatalytic reaction process, sunlight is used as the light source, and a semiconductor is used as the photocatalyst. It can effectively achieve the degradation of antibiotics through the oxidation / reduction reaction by exciting electron-hole pairs with visible light. Under normal temperature and pressure, organic pollutants can be degraded into non-toxic and harmless CO 2 and H 2 O. A particularly crucial point in photocatalytic technology is that when the catalyst is irradiated by electrons with an energy level equal to or greater than its bandgap energy, the electrons undergo a transition, and then the molecules are oxidized and reduced to degrade them. After the photocatalytic degradation of organic pollutants is irradiated by visible light, the photocatalyst is activated, and oxidation and reduction are established in the reaction system. The photo-generated electrons can react with oxygen to form superoxide radicals, or can generate hydroxyl radicals through a series of reactions, and then these two radicals degrade various pollutants into non-toxic products, while the holes can directly oxidize the pollutants. It is generally believed that electrons do not directly participate in the photocatalytic reaction, and the radicals generated by electrons act indirectly in a free form. Therefore, the main role of photocatalytic degradation of pollutants is to oxidize the pollutants and at the same time reduce oxygen to avoid the accumulation of electrons in the CB. The photocatalytic degradation of organic pollutants by MOF materials is divided into two degradation methods: one is reduction-induced degradation, and the other is oxidation-induced degradation. Summary of the Invention

[0007] To solve the above problems, the present invention provides a ternary composite material, its preparation method and application. The PDINH@MTi / P-C provided by the present invention 3 N 5 ternary composite material can efficiently degrade methylene blue and cefotaxime sodium after illumination by optimizing the material structure and broadening the light absorption range, providing a new way for the efficient degradation of organic dyes and antibiotics.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention provides a PDINH@MTi / P-C3 N 5 Preparation method of ternary composite material, comprising the following steps:

[0010] 1) Mix 2-aminoterephthalic acid, tetrabutyl titanate, dimethylformamide and anhydrous methanol, and then perform heat treatment. Wash and dry the obtained heat-treated product to obtain MTi powder;

[0011] 2) Mix 3-amino-1,2,4-triazole and phosphonitrile trichloride, and then perform calcination to obtain P-C 3 N 5 ;

[0012] The mass ratio of the 3-amino-1,2,4-triazole to the phosphonitrile trichloride is 20:3;

[0013] 3) Dissolve the MTi powder obtained in step 1) and the P-C 3 N 5 obtained in step 2) in an alcohol reagent, stir and react, remove the alcohol reagent, and dry to obtain MIL-125(Ti)-NH 2 / P-C 3 N 5 heterojunction;

[0014] 4) Mix the perylene tetracarboxylic diimide (hereinafter referred to as PDINH) solution with the MIL-125(Ti)-NH 2 / P-C 3 N 5 heterojunction obtained in step 3) and deionized water, let it stand, filter and dry the obtained standing product in sequence to obtain PDINH@MTi / P-C 3 N 5 ternary composite material.

[0015] Preferably, in step 1), the molar ratio of 2-aminoterephthalic acid, the molar ratio of tetrabutyl titanate, the volume of dimethylformamide, and the volume of anhydrous methanol is 12 mmol: 3 mmol: 54 ml: 6 ml;

[0016] The conditions of the heat treatment include: the temperature is 150 °C and the time is 16 h;

[0017] Wash with N,N-dimethylformamide and anhydrous methanol, and the number of washing times is 3 times;

[0018] The conditions of the drying include: the temperature is 75 °C and the time is 4 h.

[0019] Preferably, the conditions of the calcination in step 2) include: heating from 20-30 °C to 550 °C at 5 °C / min, holding for 4 h, cooling to 20-30 °C, and then heating to 550 °C at 5 °C / min and holding for 4 h.

[0020] Preferably, in step 3), the mass ratio of MTi powder to P-C 3 N 5 and the volume ratio of the alcohol reagent is 25 mg: 50 mg: 10 mL;

[0021] The alcohol reagent is ethanol;

[0022] The stirring reaction time is 4 h;

[0023] The alcohol reagent is evaporated and removed at 80 °C;

[0024] The drying conditions include: temperature is 180 °C, time is 2 h.

[0025] Preferably, in step 4), the instruction of the perylene tetracarboxylic diimide solution and MIL-125(Ti)-NH 2 / P-C 3 N 5 The mass ratio of the heterojunction and the volume ratio of deionized water is 100 mg: 0-800 mg: 100 mL;

[0026] The mass percentage content of the PDINH solution is 95%, the solvent of the PDINH solution is sulfuric acid solution, and the mass percentage content of the sulfuric acid solution is 98%;

[0027] The standing time is 0.5 h;

[0028] The filtration uses a 0.45 μm filter membrane for filtration;

[0029] The drying conditions include: temperature is 75 °C, time is 4 h.

[0030] The present invention also provides a PDINH@MTi / P-C prepared by the preparation method described in the above technical solution 3 N 5 ternary composite material.

[0031] The present invention also provides the PDINH@MTi / P-C described in the above technical solution 3 N 5 Application of the ternary composite material in degrading organic pollutants.

[0032] Preferably, the organic pollutants include methylene blue and / or cefotaxime sodium.

[0033] Preferably, when the organic pollutant is methylene blue, the degradation conditions include:

[0034] Adding the PDINH@MTi / P-C 3 N 5The ternary composite material is mixed with the methylene blue solution to obtain a mixture, and the mixture is degraded under visible light with a light power of 500 W;

[0035] The concentration of the methylene blue solution is 20 mg / L, and the concentration of PDINH@MTi / P-C 3 N 5 ternary composite material in the mixture is 0.334 g / L.

[0036] Preferably, when the organic pollutant is cefotaxime sodium, the degradation conditions include:

[0037] Mix the PDINH@MTi / P-C 3 N 5 ternary composite material with the cefotaxime sodium solution to obtain a mixture, and degrade the mixture under a 300 W xenon lamp with a 420 nm filter;

[0038] The concentration of the cefotaxime sodium solution is 20 mg / L, and the concentration of PDINH@MTi / P-C 3 N 5 ternary composite material in the mixture is 0.2 g / L.

[0039] Advantages of the present invention:

[0040] The preparation method of the present invention is simple and easy to implement. By bridging the heterojunction material with PDI, PDINH, MIL-125(Ti)-NH 2 and P-C 3 N 5 are compounded. The method is simple and easy to implement, the raw materials are cheap and easy to obtain, and the equipment and process are simple and easy to operate; this method has the advantages of small reagent pollution, good repeatability of the reaction, and mild preparation conditions. The obtained PDINH@MTi / P-C 3 N 5 ternary composite material broadens the light absorption range by optimizing the material structure, shows good degradation effect in the process of photocatalytic degradation of methylene blue and cefotaxime sodium, and has stable photocatalytic performance. Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments.

[0042] Figure 1 It is the SEM diagram of the PDINH@MTi / P-C 3 N 5 -6 ternary composite photocatalytic material;

[0043] Figure 2For PDINH@MTi / P-C 3 N 5 -6 X-ray energy spectrum analysis diagram;

[0044] Figure 3 For PDINH@MTi / P-C 3 N 5 -6, MTi, P-C 3 N 5 XPS diagrams and XRD diagrams of four photocatalysts of N and PDINH;

[0045] Figure 4 For PDINH@MTi / P-C 3 N 5 -6, MTi, P-C 3 N 5 UV-Vis diffuse reflectance diagrams of four photocatalysts of N and PDINH;

[0046] Figure 5 For PDINH@MTi / P-C with four ratios 3 N 5 Degradation effect diagrams of ternary composite photocatalyst on methylene blue dye;

[0047] Figure 6 Degradation effect diagrams of six photocatalysts on cefotaxime sodium. Specific implementation mode

[0048] A preparation method of a PDINH@MTi / P-C 3 N 5 ternary composite material, comprising the following steps:

[0049] 1) Mix 2-aminoterephthalic acid, tetrabutyl titanate, dimethylformamide and anhydrous methanol and then carry out heat treatment, wash and dry the obtained heat-treated product to obtain MTi powder;

[0050] 2) Mix 3-amino-1,2,4-triazole and phosphorus oxychloride trimer and then carry out calcination to obtain P-C 3 N 5 ;

[0051] The mass ratio of the 3-amino-1,2,4-triazole to the phosphorus oxychloride trimer is 20:3;

[0052] 3) Dissolve the MTi powder obtained in step 1) and the P-C obtained in step 2) 3 N 5 in an alcohol reagent and carry out a stirring reaction, remove the alcohol reagent and dry to obtain MIL-125(Ti)-NH 2 / P-C 3 N 5Heterojunction;

[0053] 4) Mix the perylene tetracarboxylic diimide solution with the MIL-125(Ti)-NH 2 / P-C 3 N 5 heterojunction and deionized water, let it stand, and then filter and dry the obtained standing product to obtain PDINH@MTi / P-C 3 N 5 ternary composite material. Perylene tetracarboxylic diimide is abbreviated as PDINH.

[0054] In the present invention, 2-aminoterephthalic acid, tetrabutyl titanate, dimethylformamide and anhydrous methanol are mixed and then subjected to heat treatment. The obtained heat-treated product is washed and dried to obtain MTi powder.

[0055] In the present invention, the molar ratio of 2-aminoterephthalic acid, the molar ratio of tetrabutyl titanate, the volume of dimethylformamide, and the volume of anhydrous methanol is 12 mmol: 3 mmol: 54 ml: 6 ml. In the present invention, the conditions of the heat treatment preferably include: the temperature is 150 °C and the time is 16 h. The present invention preferably uses N,N-dimethylformamide and anhydrous methanol for washing, and the number of washing times is preferably 3 times. In the present invention, the conditions of the drying preferably include: the temperature is 75 °C and the time is 4 h.

[0056] In the present invention, 3-amino-1,2,4-triazole and phosphonitrile chloride trimer are mixed and then calcined to obtain P-C 3 N 5 ; The mass ratio of 3-amino-1,2,4-triazole to phosphonitrile chloride trimer is 20:3. In the present invention, the conditions of the calcination preferably include: heating from 20 to 30 °C to 550 °C at a rate of 5 °C / min, holding for 4 h, cooling to 20 to 30 °C, and then heating to 550 °C at a rate of 5 °C / min and holding for 4 h.

[0057] In the present invention, the obtained MTi powder and the P-C 3 N 5 obtained in step 2) are dissolved in an alcohol reagent and stirred for reaction, the alcohol reagent is removed and dried to obtain MIL-125(Ti)-NH 2 / P-C 3 N 5 heterojunction.

[0058] In the present invention, the MTi powder and P-C 3 N 5The mass ratio of the perylene tetracarboxylic diimide solution to the obtained MIL-125(Ti)-NH

[0059] / P-C 2 / P-C 3 N 5 heterojunction and deionized water is 100 mg: 0 - 800 mg: 100 mL. After mixing and standing, the obtained standing product is filtered and dried in sequence to obtain the PDINH@MTi / P-C 3 N 5 ternary composite material.

[0060] In the present invention, the mass ratio of the perylene tetracarboxylic diimide solution to the obtained MIL-125(Ti)-NH 2 / P-C 3 N 5 heterojunction and deionized water is 100 mg: 0 - 800 mg: 100 mL. In the present invention, the mass percentage content of the PDINH solution is 95%, the solvent of the PDINH solution is a sulfuric acid solution, and the mass percentage content of the sulfuric acid solution is 98%. In the present invention, the preferred standing time is 0.5 h. In the present invention, the filtration preferably uses a 0.45 μm filter membrane. In the present invention, the drying conditions preferably include: a temperature of 75°C and a time of 4 h.

[0061] The present invention also provides a PDINH@MTi / P-C 3 N 5 ternary composite material prepared by the preparation method described in the above technical solution. In the present invention, the surface of the PDINH@MTi / P-C 3 N 5 ternary composite material is relatively rough, has many holes and is unevenly distributed, and has many irregular block stacks. It can increase the specific surface area of the photocatalyst, increase the contact area between the photocatalyst and the reactants during the photocatalytic reaction time, thereby accelerating the speed of the photocatalytic reaction and achieving a better catalytic effect.

[0062] The present invention also provides the application of the PDINH@MTi / P-C 3 N 5 ternary composite material described in the above technical solution in the degradation of organic pollutants. In the present invention, the organic pollutants preferably include methylene blue and / or cefotaxime sodium.

[0063] In the present invention, when the organic pollutant is methylene blue, the preferred degradation conditions include:

[0064] Mix the PDINH@MTi / P-C 3 N 5 ternary composite material with a methylene blue solution to obtain a mixture, and degrade the mixture under visible light with a light power of 500 W; the concentration of the methylene blue solution is 20 mg / L, and the concentration of the PDINH@MTi / P-C 3 N 5 ternary composite material in the mixture is 0.334 g / L. In the present invention, when the organic pollutant is cefotaxime sodium, the preferred degradation conditions include: Mix the PDINH@MTi / P-C 3 N 5 ternary composite material with a cefotaxime sodium solution to obtain a mixture, and degrade the mixture under a 300 W xenon lamp with a 420 nm filter; the concentration of the cefotaxime sodium solution is 20 mg / L, and the concentration of the PDINH@MTi / P-C 3 N 5 ternary composite material in the mixture is 0.2 g / L.

[0065] To further illustrate the present invention, the present invention will be described in detail below in conjunction with embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0066] Example 1

[0067] A preparation method of a PDI-bridged MIL-125(Ti)-NH 2 and P-C 3 N 5 heterojunction material, comprising the following steps:

[0068] 1. Preparation of MIL-125(Ti)-NH 2 / P-C 3 N 5 heterojunction:

[0069] (1) Typical synthesis of MTi: Weigh 2.174 g (12 mmol) of 2-aminoterephthalic acid and 1.36 ml (3 mmol) of tetrabutyl titanate, with a molar ratio of 4:1 between the two, dissolve them in 54 ml of dimethylformamide and 6 ml of anhydrous methanol, stir evenly with a magnetic stirrer, and transfer to a polytetrafluoroethylene liner. Heat in an electrothermal constant temperature drying oven at 150 °C for 16 h. Cool naturally, mix the product with 20 mL of DMF and 20 mL of anhydrous methanol, and wash 3 times. Then dry at 70 °C to obtain yellow MTi powder.

[0070] P-C3 N 5 Preparation of P-CN: Weigh 2 g of 3-AT (3-amino-1,2,4-triazole, SigmaAldrich, 98%) and 0.3 g of HCCP (phosphonitrile chloride trimer, content > 95%) according to the proportion (x is the mass ratio of P in it, x = 2%, 4%, 6% and 8%). After fully mixing, grind them. After drying, put them into a crucible. By the high-temperature solid-phase method, heat them in a muffle furnace at a heating rate of 5 °C / min to 550 °C and keep them at this temperature for 4 h. After cooling to room temperature, take them out, grind them, and then put them into the muffle furnace again and heat them at a heating rate of 5 °C / min to 550 °C and keep them at this temperature for 4 h. After the product cools naturally, P-CN samples are obtained. 3 N 5 samples.

[0071] Preparation of heterojunction: Dissolve 50 mg of MTi and 25 mg of P-CN 3 N 5 in 10 mL of ethanol and stir at room temperature for 4 h. Subsequently, heat it to 80 °C to evaporate the solvent.

[0072] After grinding the product, bake it in an oven at 180 °C for 2 h to obtain the MIL-125(Ti)-NH / P-CN heterojunction. 2 / P-CN 3 N 5 heterojunction.

[0073] 2. Preparation of PDINH@MTi / P-CN 3 N 5 :

[0074] Dissolve 100 mg of PDINH in 10 mL of 98% concentrated sulfuric acid, and then add 0, 200, 400, 600, 800 mg of MIL-125(Ti)-NH / P-CN 2 / P-CN 3 N 5 to the above solution according to the proportion. After fully stirring and dissolving, add 100 mL of deionized water to the above solution at one time.

[0075] Solid insoluble precipitates appear. Let it stand for 0.5 h, then filter and collect the dark red solid with a 0.45 μm filter membrane, wash it, and then dry it at 75 °C for 4 h to obtain four different ratios of PDINH@MTi / P-CN 3 N 5 .

[0076] The surface morphology of the PDINH@MTi / P-CN-6 composite material was characterized by SEM. 3 N 5 -6 composite material.

[0077] The prepared PDINH@MTi / P-CN 3N 5 -6 has a relatively rough surface, many holes that are unevenly distributed, and many irregular blocky stacks. It can increase the specific surface area of the photocatalyst, increase the contact area between the photocatalyst and the reactants during the photocatalytic reaction time, thereby accelerating the speed of the photocatalytic reaction and achieving a better catalytic effect.

[0078] The PDINH@MTi / P-C was characterized by XPS 3 N 5 -6, MTi, P-C 3 N 5 and four kinds of photocatalysts, namely PDINH.

[0079] The PDINH@MTi / P-C was characterized by XRD and UV-Vis-DRS 3 N 5 -6, MTi, P-C 3 N 5 and four kinds of photocatalysts, namely PDINH.

[0080] It can be seen from Figure 4 that the light absorption of the four catalysts gradually increases. Among them, the light absorption of P-C 3 N 5 and MTi is the smallest, and the light absorption of PDINH@MTi / P-C 3 N 5 -6 is the largest, indicating that by compounding the three single-component catalysts, the light absorption amount of visible light can be increased, thereby achieving the purpose of improving their optical properties.

[0081] Example 2

[0082] Degradation of organic molecule methylene blue

[0083] The degradation ability of PDINH@MTi / P-C with different ratios to methylene blue under visible light irradiation was measured. The degradation effect is as shown in (a) of 3 N 5 . Finally, the best proportion sample was determined to be PDINH@MTi / P-C Figure 5 N 3 N 5 -6 (100 mg of PDINH solution and 600 mg of MIL-125(Ti)-NH 2 / P-C 3 N 5 dissolved in 100 mL of deionized water). (The obvious degradation effect of the four ratios of PDINH@MTi / P-C on methylene blue dye can be visually seen through the change of C / C 0 3 N 5 ​3 N 5 -6 and PDINH@MTi / P-C 3 N 5 -8 both have very high photocatalytic degradation effects, among which PDINH@MTi / P-C 3 N 5 -6 has the best performance, reaching over 90%).

[0084] Meanwhile, the degradation process of methylene blue dye is described by the first-order kinetic equation, and the first-order kinetic model of methylene blue dye degradation is as shown in Figure 5 (b) below. For PDINH@MTi / P-C 3 N 5 -6, the degradation rate constant k is 12.34×10 -3 min -1 , which is higher than that of other catalysts (for PDINH@MTi / P-C 3 N 5 -2, the degradation rate constant k value is 5.83×10 -3 min -1 , and the degradation rate of methylene blue is relatively low. Compared with PDINH@MTi / P-C 3 N 5 -4, the degradation rate constant k value is 7.91×10 -3 min -1 which is similar. In contrast, for PDINH@MTi / P-C 3 N 5 -6, the degradation rate constant k is 12.34×10 -3 min -1 , and for PDINH@MTi / P-C 3 N 5 -8, the degradation rate constant k value is 11.77×10 -3 min -1 . From the above, it can be seen that the degradation rate constant k value of PDINH@MTi / P-C 3 N 5 -6 is higher than that of other catalysts), and finally it is found that PDINH@MTi / P-C 3 N 5 -6 has the best degradation effect.

[0085] Note: Figure 5 In the experiment, the concentration of methylene blue used was 20 mg / L, the concentration of the photocatalyst was 0.334 g / L, the light intensity of the multi-tube photoreactor was 500 W, samples were taken every 15 minutes of light irradiation for 3 hours, and 609 nm was selected as the measurement wavelength.

[0086] Example 3

[0087] Degradation of the antibiotic cefotaxime sodium

[0088] The absorbance of the sampling solution of photocatalytic degradation of cefotaxime sodium by different ratios of PDINH@MTi / P-C prepared in Example 1 3 N 5 was measured, as well as that of PDINH and MTi six catalysts. By comparing the ratio of the absorbance measured at each time point of each catalyst to the absorbance of the blank undegraded cefotaxime sodium solution, the degradation of cefotaxime sodium antibiotic was judged, and the differences in photocatalytic degradation performance were obtained by analyzing the first-order kinetic fitting diagram.

[0089] The degradation effect is as shown in (a) below. The degradation rate of cefotaxime sodium antibiotic by PDINH@MTi / P-C Figure 6 N 3 N 5 -6 exceeded 60% within 135 min, much higher than other catalysts. Finally, the best proportion sample was determined to be PDINH@MTi / P-C 3 N 5 -6. Within 135 min, the degradation rates of MTi and PDINH on cefotaxime sodium antibiotic were less than 20%, and their degradation efficiencies on cefotaxime sodium were very unsatisfactory. There were two ternary composite catalysts, PDINH@MTi / P-C 3 N 5 -2 and PDINH@MTi / P-C 3 N 5 -4, and the degradation rates of cefotaxime sodium maintained between 40% and 50%. The degradation effect of PDINH@MTi / P-C 3 N 5 -8 on cefotaxime sodium was not obvious, but the PDINH@MTi / P-C 3 N 5 -6 synthesized by experiment significantly enhanced the degradation efficiency of cefotaxime sodium. The degradation rate of cefotaxime sodium antibiotic by PDINH@MTi / P-C 3 N 5 -6 exceeded 60% within 135 min.

[0090] Meanwhile, the degradation process of cefotaxime sodium was described by the first-order kinetic equation. The first-order kinetic model of cefotaxime sodium antibiotic degradation is as shown in (b) below. The degradation rate constant k of PDINH@MTi / P-C Figure 6 N 3 N 5 -6 was 6.14*10 -3 min -1 , much higher than that of the ternary composite material catalysts and single-component catalysts with other ratios. Finally, it was found that PDINH@MTi / P-C 3 N5 The degradation effect of -6 is the best. The degradation rate constant k value of MTi is 0.06*10 -3 min -1 , and the degradation rate constant k value of PDINH is 0.14*10 - 3 min -1 , and their degradation rates for cefotaxime sodium antibiotics are relatively low. In contrast, the degradation rate constant k value of PDINH@MTi / P-C 3 N 5 -6 is 6.14*10 -3 min -1 , which is much higher than that of ternary composite catalysts and single-component catalysts with other ratios.

[0091] Figure 6 The concentration of cefotaxime sodium used in the experiment was 20 mg / L, and the experiment of degrading cephalosporin antibiotics was carried out under a 300 W xenon lamp with a 420 nm filter.

[0092] Put 100 mL of cefotaxime sodium solution into the photoreaction flask, sample it with a 2.5 mL sterile syringe, and then inject it into the sample tube using a 0.22 μm aqueous needle filter. Then add 0.02 g of PDINH@MTi / P-C 3 N 5 -2 (100 mg of PDINH solution and 200 mg of MIL-125(Ti)-NH 2 / P-C 3 N 5 dissolved in 100 mL of deionized water) into the photoreaction flask, ultrasonicate for 10 minutes and then perform a dark reaction for 20 minutes, and then sample again. After sampling, put the magnetic stir bar into the photoreaction flask, turn on the stirring switch and start irradiating with the Xe lamp (λ = 420 nm) for photocatalytic reaction. Sampling is carried out every 15 min, 2 mL is sampled each time, and a total of nine samplings are taken.

[0093] The samples are sealed and stored in 2.5 mL sample tubes. Then, by changing the type of catalyst, the degradation experiments of the other 5 kinds of photocatalysts are carried out in turn.

[0094] Note: Figure 6 In the experiment, HPLC was used to test the concentration of cefotaxime sodium: the mobile phase was 90% formic acid aqueous solution (0.1% deionized water acid solution) and 10% acetonitrile, the flow rate was 1.0 mL / min, and the injection volume was 60 μL.

[0095] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on this embodiment without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a PDINH@MTi / P-C3N5 ternary composite material, characterized in that: The following steps are involved: 1) 2-aminoterephthalic acid, tetrabutyl titanate, dimethylformamide and anhydrous methanol are mixed and heat-treated, and the heat-treated product is washed and dried to obtain MTi powder; 2) mixing 3-amino-1,2,4-triazole and tripolyphosphazene chloride and calcining them to obtain P-C3N5; The mass ratio of the 3-amino-1,2,4-triazole to the tripolyphosphazene chloride is 20:3; 3) dissolving the MTi powder obtained in step 1) and the P-C3N5 obtained in step 2) in an alcohol reagent and stirring to react, removing the alcohol reagent and drying to obtain a MIL-125(Ti)-NH2 / P-C3N5 heterojunction; 4) The perylenetetracarboxylic acid diimide solution is mixed with the MIL-125(Ti)-NH2 / P-C3N5 heterojunction obtained in step 3) and deionized water, and then allowed to stand. The obtained standing material is filtered and dried in turn to obtain a PDINH@MTi / P-C3N5 ternary composite material.

2. The preparation method according to claim 1, characterized in that: In the step 1), the mole ratio of 2-aminoterephthalic acid, the mole of tetrabutyl titanate, the volume of dimethylformamide, and the volume ratio of anhydrous methanol is 12 mmol: 3 mmol: 54 ml: 6 ml; The heat treatment conditions include: temperature of 150°C and time of 16h; Washing with N,N-dimethylformamide and anhydrous methanol, the washing times are 3 times; The drying conditions include: temperature of 75° C. and time of 4 hours.

3. The preparation method according to claim 1, characterized in that: The calcination conditions in step 2) include: heating from 20-30° C. to 550° C. at 5° C. / min, keeping the temperature for 4 hours, cooling to 20-30° C., then heating to 550° C. at 5° C. / min, and keeping the temperature for 4 hours.

4. The preparation method according to claim 1, characterized in that: In the step 3), the mass ratio of MTi powder to P-C3N5 and the volume ratio of alcohol reagent is 25 mg:50 mg:10 mL; The alcohol reagent is ethanol; The stirring reaction time is 4h; The alcohol reagent was removed by evaporation at 80°C; The drying conditions include: temperature of 180° C. and time of 2 hours.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the perylenetetracarboxylic acid diimide solution to the MIL-125(Ti)-NH2 / P-C3N5 heterojunction and the volume ratio of deionized water in step 4) is 100 mg: 0 to 800 mg: 100 mL; The mass percentage of the PDINH solution is 95%, the solvent of the PDINH solution is a sulfuric acid solution, and the mass percentage of the sulfuric acid solution is 98%; The standing time is 0.5h; The filtration is carried out using a 0.45 μm filter membrane; The drying conditions include: temperature of 75° C. and time of 4 hours.

6. A PDINH@MTi / P-C3N5 ternary composite material prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the PDINH@MTi / P-C3N5 ternary composite material according to claim 6 in the degradation of organic pollutants.

8. The use according to claim 7, characterized in that: The organic pollutants include methylene blue and / or ceftriaxone sodium.

9. The use according to claim 8, characterized in that: When the organic pollutant is methylene blue, the degradation conditions include: The PDINH@MTi / P-C3N5 ternary composite material is mixed with a solution containing methylene blue to obtain a mixture, and the mixture is degraded under visible light with an illumination power of 500 W; The concentration of the methylene blue solution is 20 mg / L, and the concentration of the PDINH@MTi / P-C3N5 ternary composite material in the mixture is 0.334 g / L.

10. The use according to claim 8, characterized in that: When the organic pollutant is ceftriaxone sodium, the degradation conditions include: The PDINH@MTi / P-C3N5 ternary composite material is mixed with a solution containing cefotaxime sodium to obtain a mixture, and the mixture is degraded under a 300 W xenon lamp with a 420 nm filter; The concentration of the cefotaxime sodium solution is 20 mg / L, and the concentration of the PDINH@MTi / P-C3N5 ternary composite material in the mixture is 0.2 g / L.

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