Process for the preparation of a catalyst and catalyst

Abstract

The application relates to the field of photocatalytic degradation, and provides a preparation method of a catalyst and the catalyst, which comprises the following steps: step one: TiN nanoparticles are oxidized through light irradiation to prepare a TiN / TiO2 catalyst; step two: the TiN / TiO2 catalyst is reduced in a NaBH4 aqueous solution, oxygen vacancies are introduced to the surface of the TiN / TiO2 catalyst, and then the TiN / TiO2-O v catalyst is prepared through centrifugation and drying. Accordingly, the catalytic performance of the catalyst on antibiotics can be further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photocatalytic degradation, and particularly relates to a preparation method of a catalyst capable of improving the catalytic performance on antibiotics and the catalyst. BACKGROUND

[0002] As a key drug in the fields of medical treatment and breeding, antibiotics are difficult to be completely metabolized by organisms, and a large amount of antibiotics are excreted into the water cycle system with feces and urine. Residues of various antibiotics such as β-lactams, tetracyclines, fluoroquinolones and sulfonamides have been detected in surface water, groundwater and drinking water sources. These residues not only destroy the ecological balance of water (such as inhibiting the photosynthesis of algae and interfering with the physiological functions of fish), but also accumulate through the food chain, induce bacteria to produce drug-resistant genes, and pose a potential threat to human health. The persistence of antibiotics in sewage has become an urgent environmental pressure source to be solved.

[0003] Existing technical means for treating antibiotics have limitations: the microbial degradation method has strict requirements on environmental temperature, pH value and other conditions, and the degradation rate of structurally stable antibiotics is slow; the chemical oxidation method can quickly decompose pollutants, but consumes a large amount of oxidizing agents, and the energy consumption and treatment cost are high; the physical separation method (such as membrane filtration) has low interception efficiency for low-concentration antibiotics, and the running cost is prone to skyrocketing due to membrane pollution; the adsorption method is limited by the selectivity of the adsorbent, and has poor removal effect on low-concentration antibiotics, and has problems such as narrow PH application range and difficult regeneration of adsorbent.

[0004] Photocatalytic technology can mineralize antibiotics into harmless CO2, H2 and inorganic ions by virtue of the strong oxidation ability of reactive oxygen species (such as hydroxyl radical OH, superoxide radical O2 - ) generated by photocatalysts under light, and has great potential in the field of degrading pollutants. At present, TiO2 is widely used due to its high chemical stability and low cost, but it is limited by the wide band gap of 3.2eV, and can only respond to ultraviolet light (about 7% of sunlight), the light utilization rate is low, and the recombination rate of photo-generated electron-hole pairs is high, which restricts the catalytic efficiency.

[0005] Therefore, in the prior art, how to improve the catalytic performance of the catalyst on antibiotics has become a technical problem. SUMMARY

[0006] The application aims to provide a preparation method of a catalyst capable of improving the catalytic performance of antibiotics and the catalyst. To achieve the above-mentioned purpose, one scheme of the application is a preparation method of a catalyst for photocatalytic degradation of antibiotics, comprising the following steps: step one: TiN nanoparticles are oxidized by light irradiation to prepare a TiN / TiO2 catalyst; step two: the TiN / TiO2 catalyst is reduced in a NaBH4 aqueous solution, and after oxygen vacancies are introduced on the surface of the TiN / TiO2 catalyst, the TiN / TiO2-O v catalyst is prepared through centrifugation and drying. 2 In the step one, the light irradiation intensity is 2200-2400 mW / cm v , and the light irradiation time is 10-13 s; in the step two, the concentration of the NaBH4 aqueous solution is 0.4-0.6 mol / L, and the TiN / TiO2 catalyst is reduced in the NaBH4 aqueous solution for 3-3.5 h.

[0007] In a preferred mode, the temperature for reducing the TiN / TiO2 catalyst in the NaBH4 aqueous solution is 40-60℃.

[0008] In a preferred mode, in the step two, the drying temperature is 60-100℃.

[0009] In a preferred mode, in the step two, the drying time is 6-12 h.

[0010] In addition, another aspect of the application is a catalyst prepared by the aforementioned preparation method of a catalyst for photocatalytic degradation of antibiotics; wherein the catalyst has TiO2-O v as an active center and TiN as a light-heat conversion center.

[0011] According to the aforementioned technical scheme, the light absorption capacity of the catalyst prepared by the application is significantly improved, and the reduction by the NaBH4 aqueous solution to construct oxygen vacancies also helps to enhance the adsorption and activation effect of the catalyst on antibiotic molecules. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the application, the drawings of the specification of the application will be described and explained below. Obviously, the drawings in the following description only illustrate some aspects of some exemplary embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0013] Figure 1 is the X-ray diffraction pattern of Example 1.

[0014] Figure 2is an EDS spectrum of Example 1.

[0015] Figure 3 is a plot of photocatalytic degradation of tetracycline performance of Example 1-Example 4 at antibiotic concentration of 50 mg / L.

[0016] Figure 4 is a plot of photocatalytic degradation of tetracycline performance of Example 1 and Example 5-Example 8 at antibiotic concentration of 50 mg / L.

[0017] Figure 5 is a plot of cyclic performance of photocatalytic degradation of tetracycline of Example 1.

[0018] Figure 6 is a plot of photocatalytic degradation of tetracycline performance of Example 1 and Comparative Example 1 at antibiotic concentration of 50 mg / L. DETAILED DESCRIPTION

[0019] Various exemplary embodiments of the present application are described in detail below with reference to the attached drawings. The description of exemplary embodiments is merely intended to be illustrative in nature and is not intended to limit the scope of the present application, either as to its application or use. The present application can be implemented in numerous ways, including, but not limited to, the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art. It should be noted that relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments are to be interpreted as merely exemplary, and not as a limitation unless otherwise specified.

[0020] As used in the present application, the term "include" or "comprise" and similar terms are used synonymously with each other and mean the inclusion of but not limited to, an element preceding the term so as to encompass alternatives.

[0021] As used herein, all terms (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs unless otherwise specifically defined. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0022] For components not specifically described in this section, specific types of components, parameters of components, and the interrelationship between components, and control circuitry, can be considered as technology, methods, and devices known to those skilled in the relevant art, but in appropriate cases, the technology, methods, and devices should be considered as part of the specification.

[0023] It is to be noted that, although the operations of the methods of the present application are described in a particular order, this is not meant to imply that the operations must be performed in that particular order, or that all of the operations be performed, in order to achieve the desired result. On the contrary, the steps of the present application can be changed, performed in an alternate order, and / or omitted, combined, and / or divided into additional steps, in order to achieve the desired result.

[0024] The catalyst of the present application and the method for preparing the same are described in detail as follows.

[0025] The catalyst of the present application has TiO2-O v as the active center and TiN as the light-heat conversion center, and is generally applied in the field of photocatalytic degradation of antibiotics. The active center here refers to a specific atom, atomic group or microstructure on the surface and / or inside of the catalyst, which can adsorb the reactant molecules and promote the chemical reaction thereof. In simple terms, it is the “core working area” of the catalyst. In addition, the water used in the experiments of the present application is ultrapure water, and the purchased medicines are all of analytical purity.

[0026] The preparation steps of the catalyst of the present application are as follows:

[0027] Step one: TiN nanoparticles are oxidized by light irradiation to prepare TiN / TiO2 catalyst;

[0028] Step two: the TiN / TiO2 catalyst is reduced in NaBH4 aqueous solution, oxygen vacancies are introduced on the surface of the TiN / TiO2 catalyst, and then TiN / TiO2-O v catalyst is prepared by centrifugation and drying.

[0029] As an example, in step one, commercial TiN nanoparticles are uniformly laid out, for example, on glass, and are oxidized by strong light irradiation to prepare TiN / TiO2 catalyst.

[0030] Illustratively, in step two, two oxygen atoms of a part of TiO2 molecules in the TiN / TiO2 are reduced by one oxygen atom, thereby forming a corresponding number of oxygen vacancies. Here, the oxygen vacancies are expressed as O v , because not every TiO2 molecule is reduced by one oxygen atom, but a part of TiO2 molecules are reduced by one oxygen atom to form corresponding oxygen vacancies, so it is not necessary and difficult to accurately determine the total number of oxygen vacancies formed.

[0031] The light intensity determines the TiN surface temperature, determines whether it can be converted into TiO2, the light intensity and the light time together determine the proportion of TiN to TiO2 conversion, and the distribution of TiO2 crystal form. It is well known that TiO2 crystal form plays a decisive key role in catalytic reaction, and the appropriate retention of TiN can improve the temperature of catalytic reaction and enhance the catalytic activity; and TiN can form a heterojunction with TiO2, further inhibiting carrier recombination.

[0032] In this application, after in-situ oxidation and NaBH4 reduction treatment, TiN / TiO2-O v The micro-morphology of the composite material still maintains the nanometer spherical shape, which is highly consistent with the morphology of the original commercial TiN nanoparticles. It shows that the strong light oxidation and mild reduction process does not destroy the original skeleton structure of TiN: the morphology of nanometer spherical shape not only ensures that the material has a large specific surface area, which can provide more catalytic active sites; at the same time, the complete spherical structure is beneficial to the scattering and absorption of light, reduces the loss of photon energy, and lays a structural foundation for the full-spectrum light response ability.

[0033] Based on a large number of experiments, the best conditions of light intensity, light time, NaBH4 aqueous solution concentration and reduction time are explored.

[0034] Experimental conditions: tetracycline concentration 50mg / L, catalyst dosage 0.5g / L, light conditions are natural light or using 500W xenon lamp, sampling 2mL, after centrifugation, the supernatant is taken and the antibiotic concentration in the solution is detected by ultraviolet spectrophotometer at a wavelength of 355nm.

[0035] Experimental data one: only adjust the illumination intensity, other preparation parameters remain unchanged:

[0036]

[0037] From the existing experience, the light intensity needs to be higher than 2000mW / cm 2 , so as to effectively promote the conversion of TiN to TiO2, and this light intensity condition is an important basis for follow-up experiments. Based on this, we choose to synthesize the catalyst in the range of 1500-3000mW / cm 2 , and evaluate the performance of the catalyst obtained under each synthesis condition.

[0038] The performance evaluation results clearly show that when the light intensity is higher than 2000mW / cm 2 , the degradation rate of tetracycline is significantly improved, among which in 2200mW / cm 2The degradation effect is particularly prominent under the light intensity condition, and a tetracycline degradation rate of 98% is achieved. This result is closely related to the effective transformation of TiN to TiO2 - when the light intensity is in this appropriate range, TiN can be well converted to TiO2, providing sufficient target active centers for the catalytic reaction.

[0039] When the light intensity condition is not suitable, the catalytic effect will obviously decline. On the one hand, if the light intensity is too small (such as less than 2000 mW / cm 2 ), the surface of TiN cannot reach a sufficient temperature, making it difficult to achieve effective transformation to TiO2. At this time, most of the catalyst is still TiN, with almost no target active center TiO2, so tetracycline cannot be effectively degraded. On the other hand, if the light intensity is too large, beyond the appropriate range, the crystal form of TiO2 is easily transformed into rutile phase, and a single rutile phase is not conducive to the progress of the catalytic reaction, thereby affecting the degradation effect of tetracycline.

[0040] Therefore, preferably, in the step one, the light intensity is 2200-2400 mW / cm 2 , to ensure a tetracycline degradation rate of more than 95%.

[0041] Experimental data two: only adjust the irradiation time, other preparation parameters remain unchanged:

[0042]

[0043] From the experimental results, the change of light irradiation time has a relatively limited effect on the degradation efficiency of tetracycline. This phenomenon can be analyzed in combination with the correlation between the preparation conditions and the characteristics of the catalyst: when the light intensity is determined, the temperature on the surface of the catalyst no longer fluctuates significantly, and the proportion of TiN transformed into TiO2 is basically determined.

[0044] Under this premise, the change of light irradiation time mainly affects the crystal structure of TiO2 to produce an effect on the catalytic process. Specifically, as the light irradiation time increases, the proportion of rutile phase with higher thermodynamic stability in TiO2 will gradually increase, while the proportion of anatase phase with higher catalytic activity will correspondingly decrease. Since a single rutile phase lacks sufficient surface active sites and a suitable energy band structure, it is difficult to efficiently adsorb and activate tetracycline molecules, and also cannot effectively promote the separation and migration of photo-generated charges, thus adversely affecting the smooth progress of the catalytic reaction. This is the key reason why the irradiation time has a relatively small effect on the degradation efficiency, but still needs to be reasonably controlled.

[0045] Therefore, preferably, the light irradiation time is 10-13 s, to ensure a tetracycline degradation rate of more than 95%.

[0046] Experimental data three: only adjust the concentration of NaBH4 aqueous solution, other preparation parameters remain unchanged:

[0047]

[0048] It can be seen that the concentration of NaBH4 aqueous solution as a key parameter to regulate the surface properties of the catalyst, its over-concentration or over-dilution will have a significant adverse effect on the photocatalytic degradation of tetracycline. From the mechanism of action, the appropriate concentration of NaBH4 can build a reasonable defect structure or active site on the surface of the catalyst through moderate reduction, while maintaining the integrity of its crystal structure, which not only ensures the effective separation of photo-generated charges, but also does not destroy the surface active center required for catalytic reaction.

[0049] When the NaBH4 aqueous solution is too dilute, its reduction effect is insufficient. At this time, it is difficult to form enough effective defects or active sites on the surface of the catalyst, which cannot effectively promote the separation and migration of photo-generated charges, resulting in the intrinsic catalytic activity of the catalyst being difficult to fully stimulate. At the same time, weak reduction may not be able to improve the hydrophilic or hydrophobic properties or charge distribution state of the catalyst surface, so that the adsorption ability of tetracycline molecules on the catalyst surface is weak, thereby restricting the subsequent photocatalytic degradation reaction rate, and ultimately leading to low overall degradation efficiency.

[0050] If the NaBH4 aqueous solution is too concentrated, excessive reducing substances will cause excessive reduction on the surface of the catalyst. This not only may lead to the deep reduction of the active components on the surface of the catalyst or even the precipitation of elemental substances, which destroys the original phase structure, but also makes the surface defects excessively accumulated, which becomes the recombination center of photo-generated charges, greatly reducing the charge separation efficiency.

[0051] It can be seen that when the concentration of NaBH4 aqueous solution is 0.4-0.6 mol / L, the removal rate of tetracycline can reach more than 95%.

[0052] Experimental data four: only adjust the reduction time, other preparation parameters remain unchanged:

[0053]

[0054] It can be seen that the reduction time is also crucial to the regulation of catalytic activity. The appropriate reduction time can form a stable active structure on the surface of the catalyst: enough to generate the required defects and active sites, and avoid excessive reduction to destroy the structure. If the reduction time is too short, the surface is not fully reduced, the number of active sites is insufficient, and the intrinsic activity of the catalyst is difficult to develop, which will limit the degradation efficiency of tetracycline. If the reduction time is too long, it is easy to cause excessive reduction, which leads to the destruction of the structure of active components, not only reduces the effective active sites, but also may enhance the recombination of photo-generated charges, thereby weakening the catalytic performance.

[0055] To this end, preferably, the TiN / TiO2catalyst is reduced in the NaBH4aqueous solution for 3-3.5h to ensure a tetracycline degradation rate of more than 95%.

[0056] Further preferably, the TiN / TiO2catalyst is reduced in the NaBH4aqueous solution at a temperature of 40-60℃.

[0057] Further preferably, in step two, the drying temperature is 60-100℃ and the drying time is 6-12h.

[0058] Next, the catalyst and the preparation method thereof according to the present application are further illustrated in combination with examples and comparative examples.

[0059] Example 1

[0060] (1) 75mg of commercial TiN nanoparticles were weighed and uniformly spread on a clean glass surface to ensure that the particles were not obviously accumulated. A Fresnel lens with a diameter of 10cm was selected, and the TiN particles were irradiated after focusing the strong light for 10s to complete the oxidation treatment, thereby obtaining a TiN / TiO2catalyst.

[0061] (2) A 0.5mol / L NaBH4aqueous solution was prepared, and the TiN / TiO2catalyst prepared in the previous step (1) was placed in the aqueous solution and reduced at a temperature of 40℃ for 3h. After the treatment, the TiN / TiO2-O v heterojunction was prepared by centrifugal separation, deionized water washing for 3 times, and vacuum drying.

[0062] Example 2

[0063] (1) 75mg of commercial TiN nanoparticles were weighed and uniformly spread on a clean glass surface to ensure that the particles were not obviously accumulated. A Fresnel lens with a diameter of 10cm was selected, and the TiN particles were irradiated after focusing the strong light for 5s to complete the oxidation treatment, thereby obtaining a TiN / TiO2catalyst.

[0064] (2) A 0.5mol / L NaBH4aqueous solution was prepared, and the TiN / TiO2catalyst prepared in the previous step (1) was placed in the aqueous solution and reduced at a temperature of 40℃ for 3h. After the treatment, the TiN / TiO2-O v heterojunction was prepared by centrifugal separation, deionized water washing for 3 times, and vacuum drying.

[0065] Example 3

[0066] (1) Take 75 mg of commercial TiN nanoparticles and evenly spread them on a clean glass surface, ensuring that the particles are not significantly accumulated. Select a Fresnel lens with a diameter of 10 cm, focus the strong light, and irradiate the spread TiN particles. The irradiation time is controlled to be 13 s, and the oxidation treatment is completed to obtain a TiN / TiO2 catalyst.

[0067] (2) Prepare a 0.5 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst prepared in the previous step (1) into the aqueous solution. Perform reduction treatment at a temperature of 40°C for 3 h. After the treatment, centrifugal separation, deionized water washing for 3 times, and vacuum drying are performed to obtain a TiN / TiO2-O v heterojunction.

[0068] Example 4

[0069] (1) Take 75 mg of commercial TiN nanoparticles and evenly spread them on a clean glass surface, ensuring that the particles are not significantly accumulated. Select a Fresnel lens with a diameter of 10 cm, focus the strong light, and irradiate the spread TiN particles. The irradiation time is controlled to be 20 s, and the oxidation treatment is completed to obtain a TiN / TiO2 catalyst.

[0070] (2) Prepare a 0.5 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst prepared in the previous step (1) into the aqueous solution. Perform reduction treatment at a temperature of 40°C for 3 h. After the treatment, centrifugal separation, deionized water washing for 3 times, and vacuum drying are performed to obtain a TiN / TiO2-O v heterojunction.

[0071] Example 5

[0072] (1) Take 75 mg of commercial TiN nanoparticles and evenly spread them on a clean glass surface, ensuring that the particles are not significantly accumulated. Select a Fresnel lens with a diameter of 10 cm, focus the strong light, and irradiate the spread TiN particles. The irradiation time is controlled to be 10 s, and the oxidation treatment is completed to obtain a TiN / TiO2 catalyst.

[0073] (2) Prepare a 0.1 mol / L NaBH4 aqueous solution, and place the TiN / TiO2 catalyst prepared in the previous step (1) into the aqueous solution. Perform reduction treatment at a temperature of 40°C for 3 h. After the treatment, centrifugal separation, deionized water washing for 3 times, and vacuum drying are performed to obtain a TiN / TiO2-O v heterojunction.

[0074] Example 6

[0075] (1) 75 mg of commercial TiN nanoparticles were weighed and uniformly spread on a clean glass surface to ensure that the particles were not significantly accumulated. A Fresnel lens with a diameter of 10 cm was selected, and the TiN particles were irradiated with focused light for 10 s to complete the oxidation treatment, thereby obtaining a TiN / TiO2catalyst.

[0076] (2) A 0.5 mol / L NaBH4 aqueous solution was prepared, and the TiN / TiO2catalyst prepared in the previous step (1) was placed in the aqueous solution and subjected to reduction treatment at a temperature of 40°C for 6 h. After the treatment, the TiN / TiO2-O v heterojunction was obtained.

[0077] Example 7

[0078] (1) 75 mg of commercial TiN nanoparticles were weighed and uniformly spread on a clean glass surface to ensure that the particles were not significantly accumulated. A Fresnel lens with a diameter of 10 cm was selected, and the TiN particles were irradiated with focused light for 10 s to complete the oxidation treatment, thereby obtaining a TiN / TiO2catalyst.

[0079] (2) A 0.5 mol / L NaBH4 aqueous solution was prepared, and the TiN / TiO2catalyst prepared in the previous step (1) was placed in the aqueous solution and subjected to reduction treatment at a temperature of 40°C for 6 h. After the treatment, the TiN / TiO2-O v heterojunction was obtained.

[0080] Example 8

[0081] (1) 75 mg of commercial TiN nanoparticles were weighed and uniformly spread on a clean glass surface to ensure that the particles were not significantly accumulated. A Fresnel lens with a diameter of 10 cm was selected, and the TiN particles were irradiated with focused light for 10 s to complete the oxidation treatment, thereby obtaining a TiN / TiO2catalyst.

[0082] (2) A 0.5 mol / L NaBH4 aqueous solution was prepared, and the TiN / TiO2catalyst prepared in the previous step (1) was placed in the aqueous solution and subjected to reduction treatment at a temperature of 40°C for 6 h. After the treatment, the TiN / TiO2-O v heterojunction was obtained.

[0083] Comparative Example 1

[0084] A 0.5 mol / L NaBH4 aqueous solution was prepared, and a commercially available TiO2 catalyst was added to this solution. Reduction treatment was carried out at 40°C for 3 hours. After treatment, TiO2-O was obtained by centrifugation, washing three times with deionized water, and vacuum drying. v .

[0085] like Figure 1 As shown, X-ray diffraction (XRD) analysis was performed on the sample prepared in Example 1. The results showed that after in-situ oxidation under strong light irradiation and reduction with NaBH4, the diffraction peaks of the product highly matched the characteristic peaks of anatase TiO2 and rutile TiO2, and the rutile phase diffraction peaks were more intense, indicating that TiO2 in the product existed in a mixed crystal form with rutile phase as the main component and anatase phase as the auxiliary component. It is worth noting that the characteristic diffraction peaks of TiN did not appear in the XRD pattern. This is related to the fact that most of TiN was converted into TiO2 during the oxidation process, and the remaining content was low and highly dispersed. Its low content did not provide sufficient response for the XRD detection sensitivity.

[0086] like Figure 2 As shown, scanning electron microscopy (SEM) characterization revealed that, after in-situ oxidation and NaBH4 reduction treatment, the TiN / TiO2-O prepared in Example 1... v The composite material retains its microstructure as nanospheres with a diameter of approximately 50-80 nm, highly consistent with the morphology of the original commercial TiN nanoparticles. This result indicates that the strong photo-oxidation and mild reduction processes did not destroy the original framework structure of TiN: the nanosphere morphology not only ensures a large specific surface area, providing more catalytic active sites, but also the intact spherical structure facilitates light scattering and absorption, reducing photon energy loss and laying the structural foundation for full-spectrum photoresponse capability.

[0087] Of all the embodiments, Example 1 (10s illumination time) showed the best activity. If the illumination time is too short, it is not enough to convert TiN into TiO2 in large quantities. TiN alone has poor ability to degrade tetracycline. If the illumination time is too long, the crystal form of TiO2 will be completely converted into the rutile phase. A single crystal form is not conducive to the catalytic reaction.

[0088] Specifically, this is directly related to the evolution law of TiO2 crystal form: when the light time is too short (such as 5s in Example 2), TiN is not completely oxidized, and the amount of generated TiO2 is small and mainly exists in amorphous or low crystallinity form. At this time, the proportion of TiN in the system is relatively high, and pure TiN has weak degradation ability on tetracycline (60 min degradation rate is only 44%) due to the lack of photocatalytic active centers (oxygen vacancies and heterojunction structure of TiO2). When the light time is too long (such as 20s in Example 4), TiN is almost completely oxidized to TiO2, and although the single rutile phase has high thermal stability, the recombination rate of photo-generated electron-hole pairs is fast, and the catalytic activity is significantly reduced (60 min degradation rate is reduced to 85%). The 10s light condition of Example 1 can precisely control the crystal form ratio of TiO2, while retaining an appropriate amount of TiN to form a heterojunction, thereby maximizing activity. At the same time, the 13s light condition of Example 3 is also within the preferred light time range of the present application, so it can also achieve better activity as shown in Figure 3 .

[0089] As shown in Figure 4 , by comparing the tetracycline degradation performance under different reduction conditions, the regulation law of NaBH4 reduction parameters on catalytic activity can be determined: under the conditions of NaBH4 concentration of 0.5mol / L, reduction temperature of 40℃, and reaction time of 3h (Example 1), the 60min degradation rate of the catalyst on 50mg / L tetracycline reaches 98%, which is directly related to the precise regulation of oxygen vacancy concentration. If the concentration of NaBH4 is too low (such as 0.1mol / L, Example 5), it will lead to insufficient generation of oxygen vacancies, and the adsorption ability of the catalyst on tetracycline will be weak. If the concentration of NaBH4 is too high (such as 1mol / L, Example 6), it will cause excessive reduction and form a large number of disordered defects, which will become electron-hole recombination centers. If the reaction time in NaBH4 is too short (1h, Example 7), the oxygen vacancy concentration is insufficient, and if the reaction time is too long (6h, Example 8), it may cause partial structure collapse of TiO2-O v , which will reduce the catalytic activity.

[0090] As shown in Figure 5 , the cyclic stability test of the catalyst further verifies its potential for practical application: the catalyst of Example 1 is used for 6 cycles (after each use, it is separated by centrifugation at 10000rpm for 3min, washed with deionized water for 3 times, and regenerated by vacuum drying at 80℃ for 12h), and the 60min degradation rate of tetracycline remains above 97%, which indicates that the TiN / TiO2-O v heterojunction structure has good chemical stability, and the oxygen vacancies are not easily lost in the cyclic reaction, providing a reliable guarantee for its long-term practical application.

[0091] Figure 6This is a graph showing the photocatalytic degradation performance of tetracycline in Example 1 and Comparative Example 1 at an antibiotic concentration of 50 mg / L. Figure 6 As shown, under the condition that the NaBH4 reduction process parameters (including NaBH4 dosage, reduction temperature, reaction time, etc.) are completely consistent with those in Example 1, TiO2-O is prepared by direct single reduction treatment using commercial TiO2. v Its activity was still significantly lower than that of Example 1. Despite the same NaBH4 reduction conditions, commercial TiO2, after single reduction, could only form a certain amount of oxygen vacancies on the surface and lacked the synergistic effect of the TiN phase: on the one hand, without TiN as an electron-capturing center, photogenerated electron-hole pairs easily recombine, resulting in insufficient light absorption efficiency conversion and inability to effectively stimulate the active free radicals required for antibiotic degradation; on the other hand, the activity of commercial TiO2-O2 alone was significantly lower than that of Example 1. v The surface adsorption capacity is weak, and due to the crystal structure and surface state of commercial TiO2 itself, even under the same reduction conditions, it is impossible to form an efficient reaction cycle of "adsorption-activation-degradation".

[0092] In summary, this invention innovatively combines in-situ oxidation with NaBH4 reduction to successfully prepare TiN / TiO2-O with high oxygen vacancy content. v Heterogeneous structure. Experiments have verified that this synthesized TiN / TiO2-O... v Under full light conditions, the TiN / TiO2 composite catalyst exhibits excellent antibiotic degradation activity. Its heterojunction structure effectively promotes electron-hole separation, while TiN's narrow bandgap broadens the photoresponse range into the infrared region. Furthermore, TiN's excellent infrared absorption and high photothermal conversion efficiency further accelerate the activation and degradation of antibiotic molecules through thermal effects, significantly improving the degradation of various antibiotics.

[0093] Among these methods, introducing oxygen vacancies via NaBH4 reduction is simple and easy, and the concentration of oxygen vacancies on the catalyst surface can be precisely controlled by adjusting the reduction concentration, temperature, and time. Thanks to the presence of TiN, the light absorption capacity of the prepared catalyst is significantly improved; and the construction of oxygen vacancies helps to enhance the adsorption and activation effect of antibiotic molecules on the catalyst.

[0094] It should be understood that the specific embodiments described above are only used to explain this application, and the scope of protection of this application is not limited thereto. Any changes, substitutions, or combinations made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be covered within the scope of protection of this application.

Claims

1. A method for preparing a catalyst for photocatalytic degradation of antibiotics, characterized by, The method comprises the following steps: Step 1: TiN nanoparticles are oxidized by light to obtain TiN / TiO2 catalyst; Step two: the TiN / TiO2catalyst is treated with a NaBH4aqueous solution, after introducing oxygen vacancies on the surface of the TiN / TiO2catalyst, centrifugation, drying to obtain TiN / TiO2-O v catalyst In the step one, the light intensity is 2200-2400 mW / cm 2 , and the light time is 10-13 s. In the step 2, the concentration of the NaBH4 aqueous solution is 0.4-0.6 mol / L, and the TiN / TiO2 catalyst is reduced in the NaBH4 aqueous solution for 3-3.5 h.

2. The method according to claim 1, wherein the TiN / TiO2 catalyst is reduced in the NaBH4 aqueous solution at a temperature of 40-60℃.

3. The method according to claim 1, wherein the drying temperature in the step 2 is 60-100℃.

4. The method according to claim 3, wherein the drying time in the step 2 is 6-12 h.

5. A catalyst prepared by the method according to any one of claims 1-4. ​ ​ ​ ​ The catalyst is TiO2-O v TiN is the light-heat conversion center.

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