Composite photo-fenton catalyst, and preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of photocatalysts, and in particular to a microspherical TiO2-x / C / FeMn-LDHS / g-C3N4 composite photo-Fenton catalyst, and a preparation method therefor and a use thereof. The preparation method in the present invention is simple and the process is controllable. The prepared microspherical TiO2-x / C / FeMn-LDHS / g-C3N4 material has the advantages of combined spherical structure and layered structure, heterojunction, carbon layer protection, and stabilized oxygen vacancies while retaining the redox properties of TiO2, improves the conversion efficiency of photo-generated electrons, has high catalytic performance and a stable structure, and when used as a photo-Fenton catalyst, has important applications in the field of efficient removal of ammonia nitrogen and lipophilic antibiotics in water.

Description

Composite photo-Fenton catalyst and preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of photocatalysts, in particular to a microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst and preparation method and application thereof. BACKGROUND

[0002] With the rapid development of global agriculture and industrialization, the discharge of domestic sewage and industrial wastewater increases, and the concentration of nitrogen-containing compounds in sewage and wastewater increases, especially the increase of ammonia nitrogen, which aggravates water eutrophication and seriously damages the water ecological environment. At present, the main methods for denitrification are physical stripping, physical adsorption, biological degradation, chemical precipitation, electrochemical oxidation, breakpoint chlorination and the like. These methods are either high in cost or low in efficiency, and the breakpoint chlorination method also produces residual chlorine. Therefore, there is an urgent need for a new denitrification technology with high efficiency, low cost and no secondary pollution. Since ammonia nitrogen and organic pollutants often occur simultaneously, their simultaneous removal has very important application value.

[0003] Advanced oxidation technology (AOP s ) is a new type of oxidation treatment technology that has attracted much attention at present, which mainly plays a role through the strong oxidizing substances (·OH, ·Cl, ·SO4, etc.) generated by the reaction. Photocatalytic oxidation, as a kind of advanced oxidation technology, is considered to be an ideal method for effectively removing refractory organic matter and ammonia nitrogen. Photocatalytic oxidation technology is to add a semiconductor photocatalyst to the reaction solution, and under the condition of ultraviolet light or visible light irradiation, ·OH with strong oxidizing ability is generated, which reacts with pollutants through oxidation-reduction reaction to generate CO2 and other inorganic small molecules. Photocatalytic oxidation technology has the characteristics of wide application range, good removal effect and no secondary pollution, and also has good removal effect on some special substances such as cyanide and bacteria.

[0004] The core of photocatalytic oxidation technology is a semiconductor catalyst. TiO2 is a common semiconductor photocatalyst. Under light irradiation, the electrons inside the TiO2 photocatalyst are activated to form electron-hole pairs, which can form ·OH with OH-, H2O and dissolved oxygen in water, and have the advantages of high catalytic activity, good stability, complete mineralization, no secondary pollution, low cost and non-toxicity, etc. Therefore, TiO2 has become a research hotspot of semiconductor photocatalysts, and has a good application prospect in environmental governance. However, TiO2 has a large band gap, and the photo-generated electron-hole pairs are prone to recombine during transfer. In addition, powder TiO2 photocatalyst is prone to agglomeration, which reduces the specific surface area and leads to low quantum utilization rate of TiO2.

[0005] In recent years, a large number of studies have shown that the coupling of semiconductor materials with different band gaps is one of the effective methods to achieve visible light response characteristics and enhance its catalytic performance. Graphene-like carbon nitride (g-C3N4) is considered to be one of the best photocatalysts due to its narrow band gap width (~2.7 eV) and unique semiconductor band structure, excellent stability and non-toxicity. Currently, g-C3N4 is used for various photocatalytic reactions, including pollutant degradation, CO2 reduction and water photolysis. However, due to its poor ability to absorb visible light, low efficiency of photo-induced charge separation and limited surface reaction sites, the photocatalytic efficiency of g-C3N4 itself is relatively low, and therefore, there is an urgent need to modify it to improve the activity and stability of the catalyst.

[0006] Chinese patent document CN 113828294 A discloses a preparation method of a nano TiO2 / g-C3N4 photocatalytic material. First, tetrabutyl titanate and urea are dissolved in anhydrous ethanol to obtain tetrabutyl titanate solution and urea solution. Then, the urea solution is added dropwise to the tetrabutyl titanate solution to obtain a mixed solution. A mixed solution of deionized water and acetic acid is added dropwise to the mixed solution until a sol is formed. Then, the sol is aged and dried. The obtained solid powder is placed in a muffle furnace, heated to 500-600℃, and sintered. Finally, the furnace is cooled to room temperature, and after grinding, the nano TiO2 / g-C3N4 photocatalytic material is obtained. Although this method is simple to operate and the TiO2 and g-C3N4 are uniformly mixed, the obtained powder is prone to agglomeration. SUMMARY

[0007] In view of the shortcomings of existing photocatalysts, the purpose of the present application is to provide a composite photo-Fenton catalyst with high catalytic performance, stable structure and significantly improved electron transfer efficiency, as well as a preparation method and application thereof.

[0008] To achieve this purpose, the following technical solutions are adopted in the present application:

[0009] The first aspect of the present application provides a microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst, and a preparation method thereof, the specific technical solutions are as follows:

[0010] The first aspect of the present application provides a microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst, and a preparation method thereof, the specific technical solutions are as follows:

[0011] (1) TiO2 hollow microspheres are used as raw materials, and in-situ chemical reduction method is adopted to prepare TiO2xO4-xhollow microspheres, wherein 0.1≤x≤2; 2-x

[0012] (2) TiO2xO4-xhollow microspheres are mixed with g-C3N4 to obtain a composite photo-Fenton catalyst. 2-x ​Hollow microspheres are activated, and sodium carboxymethyl cellulose is coated onto the activated TiO2. 2-x The surface of hollow microspheres is pyrolyzed and carbonized to obtain microspherical TiO2. 2-x / C;

[0013] (3) Using the co-precipitation method in TiO 2-x Manganese-iron layered double hydroxides were prepared on the C surface to obtain microspheres of TiO2. 2-x / C / FeMn-LDH S ;

[0014] (4) TiO 2-x / C / FeMn-LDH S Microspheres of TiO2 were obtained by combining it with g-C3N4 via chemical bath deposition. 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst.

[0015] A second aspect of the present invention provides microsphere TiO2 prepared by the above-described preparation method. 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst.

[0016] The third aspect of the present invention provides the above-mentioned microspherical TiO₂. 2-x / C / FeMn-LDH S Application of / g-C3N4 composite photo-Fenton catalyst in the catalytic degradation of ammonia nitrogen and lipophilic antibiotics in wastewater or sludge tailings.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The microsphere TiO provided by this invention 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst, hollow TiO2 microspheres, possesses excellent permeability and light utilization; and the reduced TiO2... 2-x Microspheres enable the composite material to have a higher photoresponse and light absorption range; TiO 2-x The carbon layer coating on the surface can protect Ti 3+ / O VS It is not oxidized, thus achieving high-efficiency transfer of photogenerated electrons, thereby improving its catalytic performance and efficiency;

[0019] 2. TiO 2-x The amorphous carbon formed by carbonizing sodium carboxymethyl cellulose coated on the surface of hollow spheres has a higher specific surface area, higher porosity and better electron transport capacity compared with other carbon sources, providing more active sites for catalysis.

[0020] 3. The microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst, g-C3N4 and TiO 2-x The heterojunction structure between g-C3N4 and TiO

[0021] 4. The microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst, FeMn-LDH S coated on the surface of TiO 2-x / C, the spherical and layered composite material formed is beneficial to the improvement of the performance of the catalyst, significantly improves the specific surface area of the catalyst, improves the catalytic activity, and the interlayer anion of the metal hydroxide can adsorb PO4 3- in the form of phosphorus, and with the increase of the surface negative charge density, it is beneficial to the adsorption of NH4 + , and exhibits the effect of synergistic adsorption of nitrogen and phosphorus with amorphous carbon.

[0022] 5. The microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst, the iron-manganese hydroxide, g-C3N4, amorphous carbon and other materials with strong absorption to sunlight and visible light are compounded, which further enhances the absorption of the photocatalyst to sunlight and visible light, improves the photocatalytic efficiency, and has good effect on the efficient removal of ammonia nitrogen and lipophilic antibiotics in water as a photo-Fenton catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a scanning electron microscope image of the TiO 2-x hollow microspheres at different magnifications.

[0024] Figure 2 is a scanning electron microscope image of the product microspherical TiO 2-x / C with different mass ratios of TiO 2-x hollow microspheres and sodium carboxymethyl cellulose; wherein (a) the mass ratio of TiO 2-x hollow microspheres and sodium carboxymethyl cellulose is 1:2; (b) the mass ratio of TiO 2-x hollow microspheres and sodium carboxymethyl cellulose is 1:3; (c) the mass ratio of TiO 2-x hollow microspheres and sodium carboxymethyl cellulose is 1:4; (d) the mass ratio of TiO 2-x hollow microspheres and sodium carboxymethyl cellulose is 1:5; (e) the mass ratio of TiO 2-x hollow microspheres and sodium carboxymethyl cellulose is 1:6.

[0025] Figure 3 shows the TiO2 in Example 2. 2-x The product of hollow microspheres and sodium carboxymethyl cellulose in a mass ratio of 1:4 is microspherical TiO2. 2-x / C surface magnified scanning electron microscope image.

[0026] Figure 4 shows the microsphere TiO2 product obtained by using glucose as a carbon source in Comparative Example 1. 2-x Scanning electron microscope image of / C.

[0027] Figure 5 shows the microsphere TiO2 in Example 1. 2-x / C / FeMn-LDH S Scanning electron microscope images at different magnifications.

[0028] Figure 6 shows the microsphere TiO2 in Example 1. 2-x / C / FeMn-LDH S Scanning electron microscope image of the / g-C3N4 composite photo-Fenton catalyst.

[0029] Figure 7 shows the microsphere TiO2 in Example 1. 2-x / C / FeMn-LDH S Transmission electron microscopy image of the / g-C3N4 composite photo-Fenton catalyst.

[0030] Figure 8 shows the microsphere TiO2 in Example 1. 2-x / C / FeMn-LDH S X-ray diffraction pattern of / g-C3N4 composite photo-Fenton catalyst.

[0031] Figure 9 shows the microsphere TiO2 in Example 1 and Comparative Example 4. 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst and microspherical TiO2 / C / FeMn-LDH S Tauc diagram of / g-C3N4 composite photo-Fenton catalyst.

[0032] Figure 10 shows different TiO₂ values. 2-x Microspheres of TiO2 with a mass ratio of hollow microspheres to sodium carboxymethyl cellulose 2-x / C / FeMn-LDH S PL spectrum of / g-C3N4 composite photo-Fenton catalyst. Detailed Implementation

[0033] This invention designs and synthesizes a simple and controllable microsphere TiO2 with magnetic recyclability, high catalytic performance, and stable structure. 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst was first synthesized using a hydrothermal method to obtain TiO2 hollow microspheres, which were then reduced with a reducing agent to prepare TiO2. 2-x Hollow microspheres were then activated using a dilute acid solution to hydroxylate their surface; TiO2 2-x The activated hydroxyl groups on the surface of hollow microspheres and the hydroxyl groups on the surface of sodium carboxymethyl cellulose (CMC-Na) adsorb onto TiO2 through hydrogen bonding. 2-x On the surface of hollow microspheres, after pyrolysis and carbonization, CMC-Na in TiO 2-x A 5–10 nm amorphous carbon layer is formed on the surface of hollow microspheres by carbonization, which can protect Ti. 3+ / O VS It is not oxidized, and then co-precipitation is used in TiO2 with Fe / Mn salt as a precursor. 2-x FeMn-LDHs were generated on the surface of the / C microspheres, and finally, g-C3N4 was coated onto TiO2 using a precipitation method. 2-x / C / FeMn-LDH S On the surface, a catalyst with high catalytic performance and stable structure is prepared, which combines the advantages of spherical and layered structures, heterojunction, carbon protection and stable oxygen vacancies, and can significantly improve electron transfer efficiency.

[0034] The following details the microspherical TiO2 of the present invention. 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst, its preparation method and application.

[0035] The first aspect of the present invention provides microsphere TiO2. 2-x / C / FeMn-LDH S The preparation method of / g-C3N4 composite photo-Fenton catalyst includes the following steps:

[0036] (1) TiO2 hollow microspheres were used as raw materials to prepare TiO2 by in-situ chemical reduction method. 2-x Hollow microspheres, where 0.1 ≤ x ≤ 2;

[0037] (2) TiO 2-x Hollow microspheres are activated, and sodium carboxymethyl cellulose is coated onto the activated TiO2. 2-x The surface of hollow microspheres is pyrolyzed and carbonized to obtain microspherical TiO2. 2-x / C;

[0038] (3) Using the co-precipitation method on microsphere TiO2 2-x Manganese-iron layered double hydroxides were prepared on the C surface to obtain microspheres of TiO2. 2-x / C / FeMn-LDH S ;

[0039] (4) The microspherical TiO 2-x / C / FeMn-LDH S The microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst is prepared.

[0040] In some embodiments of the present application, in step (1), the method for preparing the TiO2 hollow microspheres comprises: using a Ti salt as a precursor, ethanol as a solvent, and urea as an organic additive to perform a hydrothermal reaction, thereby obtaining TiO2 hollow microspheres. In some embodiments of the present application, the Ti salt is selected from any one of Ti(SO4)2, TiCl4, and Ti(S2O7)2. In some embodiments of the present application, the molar ratio of the Ti salt to urea is 1:1-2. In some embodiments of the present application, the mass of urea to the volume of ethanol in the urea-ethanol solution formed by the urea and the ethanol is 0.02-0.05 g / mL. Preferably, the concentration of the ethanol is 95 wt%. In some embodiments of the present application, the reaction temperature of the hydrothermal reaction is 120-140°C, and the reaction time is 12-14 h.

[0041] In some embodiments of the present application, in step (1), the in-situ chemical reduction method comprises: adding the TiO2 hollow microspheres into a reducing agent solution, performing a reduction reaction at room temperature, and then washing and drying to obtain TiO 2-x hollow microspheres. In some embodiments of the present application, the reducing agent is selected from any one or several of NaBH4, KBH4, and H2C2O4. Preferably, the solvent of the reducing agent solution is water, and the concentration of the reducing agent in the reducing agent solution is 0.1-0.5 mol / L. In some embodiments of the present application, magnetic stirring is performed during the reduction reaction. In some embodiments of the present application, the washing medium is water. In some embodiments of the present application, the drying temperature of the drying is 60-80°C, and the drying time is 12-24 h.

[0042] In some embodiments of the present application, in step (2), the activation treatment comprises: placing the TiO 2-x hollow microspheres in a dilute acid solution for ultrasonic treatment. In some embodiments of the present application, the dilute acid solution is selected from any one of dilute hydrochloric acid, dilute nitric acid, dilute sulfuric acid, and hydrofluoric acid. In some embodiments of the present application, the concentration of the dilute acid solution is 0.0005-0.01 mol / L.

[0043] In some embodiments of the present application, in step (2), the sodium carboxymethyl cellulose is coated on the activated TiO 2-xThe surface of the hollow microspheres includes: activated TiO2 2-x Hollow microspheres were dispersed in a sodium carboxymethyl cellulose solution, allowing the sodium carboxymethyl cellulose to coat the activated TiO2. 2-x Hollow microsphere surface. In some embodiments of the present invention, the TiO₂... 2-x The mass ratio of hollow microspheres to sodium carboxymethyl cellulose is 1:3-5. Based on the experimental results in the embodiments of this invention, it can be seen that TiO₂... 2-x When the mass ratio of hollow microspheres to sodium carboxymethyl cellulose increases from 1:2 to 1:5, the TiO₂ content increases with the increase of sodium carboxymethyl cellulose concentration. 2-x The carbon layer coating rate on the surface of hollow microspheres gradually increases, but when the sodium carboxymethyl cellulose concentration is too high (TiO2), the coating rate decreases. 2-x A mass ratio of hollow microspheres to sodium carboxymethyl cellulose (1:6) was found to be undesirable. This is presumably because excessively high sodium carboxymethyl cellulose concentrations may cause it to self-assemble into micelle structures, forming a colloidal suspension, thus affecting its performance in TiO₂. 2-x The adsorption on the surface of hollow microspheres affects the coating of the surface carbon layer; as can be seen from Figure 2e, a large number of cluster structures appear around the microspheres, which also confirms this.

[0044] In some embodiments of the present invention, in step (2), the pyrolysis temperature is 400–600°C, and the pyrolysis time is 3–5 h. In some embodiments of the present invention, the pyrolysis is performed using a programmed temperature increase at a rate of 5–10°C / min.

[0045] In some embodiments of the present invention, in step (2), the product after pyrolysis and carbonization needs to be washed, centrifuged, and dried to obtain microsphere TiO2. 2-x / C. In some embodiments of the present invention, the washing is performed by sequentially washing with deionized water and ethanol. In some embodiments of the present invention, the drying temperature is 80–90°C, and the time is 10–12 hours.

[0046] In some embodiments of the present invention, step (3) of the co-precipitation method includes the following steps: ultrasonically treating a mixed salt solution of ferric salt and divalent manganese salt, and adding it dropwise to a mixed alkaline solution of NaOH and Na2CO3, maintaining the pH at 9.5-10.5; after the addition is complete, adding microspheres of TiO2. 2-x / C, ultrasonic treatment, after the precipitation reaction is complete, followed by washing and drying to obtain microspheres of TiO2. 2-x / C / FeMn-LDH S In some embodiments of the present invention, the Fe in the mixed salt solution 3+ Mn 2+ The molar ratio is 1-2:1-5; preferably, the Fe in the mixed salt solution of the trivalent iron salt and divalent manganese salt is... 3+concentration of 0.1-1.0 mol / L, Mn 2+ concentration of 0.1-1.0 mol / L. In some embodiments of the present application, the mass ratio of Fe3+ to microspherical TiO 2-x / C is 1-2:1. In some embodiments of the present application, the temperature of the precipitation reaction is 150-170℃, and the reaction time is 3-5h. In some embodiments of the present application, the ultrasonic treatment time is 10-20min. In some embodiments of the present application, the washing is sequentially using deionized water and ethanol; in some embodiments of the present application, the drying method is vacuum drying, the drying temperature is 50-70℃, and the drying time is 2-4h.

[0047] In some embodiments of the present application, in step (4), the chemical bath deposition method comprises: dissolving TiO 2-x / C / FeMn-LDH S , g-C3N4 in deionized water, ultrasonic treatment, stirring reaction, and aging the reaction product overnight after washing to obtain microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst. In some embodiments of the present application, the concentration of Fe3+ is 0.1-1.0 mol / L, and the concentration of Mn 2-x / C / FeMn-LDH S , g-C3N4 is 1:1-3. In some embodiments of the present application, the ultrasonic treatment time is 10-30min. In some embodiments of the present application, the washing is sequentially using deionized water and ethanol. In some embodiments of the present application, the aging temperature is 55-65℃, and the aging time is 12-24h.

[0048] The second aspect of the present application provides the microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst prepared by the preparation method of the microspherical TiO 2-x / C / FeMn-LDH / C / FeMn-LDH, the amorphous carbon layer coated outside the inner core layer, the iron-manganese bimetallic hydroxide layer deposited on the surface of the amorphous carbon layer, and the g-C3N4 layer assembled on the surface of the iron-manganese bimetallic hydroxide layer.

[0049] The third aspect of the present application provides the application of the composite photo-Fenton catalyst in catalytic degradation of ammonia nitrogen and lipophilic antibiotics in sewage or sludge tail water.

[0050] In some embodiments of the present application, the composite photo-Fenton catalyst is applied to catalytic degradation of ammonia nitrogen and lipophilic antibiotics in wastewater or sludge tail water, comprising the following steps: adding the prepared microspherical TiO 2-x / C / FeMn-LDH S The / C / FeMn-LDH / g-C3N4 composite photo-Fenton catalyst is added to the water body containing ammonia nitrogen and lipophilic antibiotics, H2O2 solution is added, and photocatalytic degradation is carried out under visible light. Preferably, the concentration of ammonia nitrogen in the water body is 10-50 mg / L, the concentration of lipophilic antibiotics is 10-100 mg / L, the dosage of H2O2 solution is 1.5-5.0 mL / L, the dosage of catalyst is 10-50 mg / L, and the degradation time is 30-120 min.

[0051] In some embodiments of the present application, the antibiotics include quinolone antibiotics, macrolide antibiotics, tetracycline antibiotics, sulfonamide antibiotics, etc. The quinolone antibiotics include norfloxacin, ciprofloxacin, enrofloxacin, ofloxacin, etc.; the macrolide antibiotics include azithromycin, erythromycin, etc.; the tetracycline antibiotics include tetracycline, chlortetracycline, oxytetracycline, etc.; and the sulfonamide antibiotics include sulfadimidine, sulfamethoxazole, etc.

[0052] The specific embodiments of the present application are further described in detail below with reference to the preferred embodiments. When the embodiments give numerical ranges, it should be understood that, unless otherwise specified by the present application, both endpoints of each numerical range and any number between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present application have the same meanings as commonly understood by those skilled in the art. In addition to the specific methods, devices, materials used in the embodiments, any method, device and material of the prior art similar or equivalent to those described in the embodiments of the present application can also be used to implement the present application, as long as they are within the scope of the present application.

[0053] Example 1

[0054] A microspherical TiO 2-x / C / FeMn-LDH S The preparation method of the / C / FeMn-LDH / g-C3N4 composite photo-Fenton catalyst comprises the following steps:

[0055] (1) Weigh 10 g of Ti(SO4)2 and add it to a mixture of 2.5 g of urea and 50 mL of 95 wt% ethanol, mix well, then transfer the solution to a 150 mL polytetrafluoroethylene-lined reaction kettle, react at 140°C for 12 h, naturally cool to room temperature, centrifuge, wash the product with deionized water and ethanol several times, and vacuum dry at 80°C for 12 h to obtain the product TiO2 hollow microspheres; add the prepared hollow microspheres to a 0.1 mol / L NaBH4 solution, magnetically stir at room temperature for 60 min, and finally wash with deionized water several times and dry at room temperature to obtain TiO 2-x hollow microspheres; the SEM characterization results of the product are shown in Figure 1.

[0056] (2) Weigh 5 g of TiO 2-x hollow microspheres into 20 mL of 0.0015 mol / L dilute nitric acid solution, ultrasonic for 10 min, and after centrifugation, disperse it in 70 mL of 0.82 mol / L sodium carboxymethyl cellulose solution (TiO 2-x hollow microspheres and sodium carboxymethyl cellulose have a mass ratio of 1:3), ultrasonic for 20 min, vacuum suction filtration, and the TiO 2-x hollow microspheres coated with sodium carboxymethyl cellulose are transferred to a muffle furnace, heated to 500°C at a heating rate of 5°C / min and kept for 5 h, naturally cooled to room temperature, washed with deionized water and ethanol several times, centrifuged, and vacuum dried at 85°C for 10 h to obtain the product microspherical TiO 2-x / C; the SEM characterization results of the product are shown in Figure 2b.

[0057] (3) Ultrasonic 25 mL of 1.0 mol / L Fe(NO3)3·9H2O and 25 mL of 1.0 mol / L Mn(NO3)2·4H2O mixed salt solution for 20 min, add 7 g of microspherical TiO 2-x / C, stir well; dissolve 0.03 mol of NaOH and 0.015 mol of Na2CO3 in 100 mL of water, stir for 30 min to form a mixed alkali solution; add the mixed alkali solution dropwise to the mixed salt solution, keep the pH stable for 10, ultrasonic for 30 min after the addition is completed, and react at 150°C for 3 h under oil bath conditions, naturally cool to room temperature, centrifuge, wash the product with deionized water and ethanol several times, and vacuum dry at 70°C for 3 h to obtain the product microspherical TiO 2-x / C / FeMn-LDH S ; the SEM characterization results of the product are shown in Figure 5.

[0058] (4) Weigh 3 g of microspherical TiO 2-x / C / FeMn-LHD S, 3g g-C3N4 nanosheets were dissolved in 50 mL deionized water, ultrasonic for 2 min, stirring at 35℃ for 3h, the product was washed with water and ethanol several times, and then put into the oven at 60℃ for 12h to get the microspherical TiO 2-x / C / FeMn-LHD S The SEM, TEM and XRD characterization results of the product of the g-C3N4 composite photo-Fenton catalyst are shown in Figures 6-8.

[0059] Figures 1, 2b, 5-6 are scanning electron micrographs of the product obtained in each step of Example 1. As can be seen from Figure 1, the TiO 2-x The hollow microspheres sample is in the form of microspheres; as can be seen from Figure 2b, 5-6 compared with Figure 1: the surface of the microspheres coated with a carbon layer is rougher than the surface of the TiO2 microspheres, and the surface of the microspheres further coated with double metal oxides and g-C3N4 is even rougher, which directly indicates that the material is successfully compounded.

[0060] Figure 7 is a transmission electron micrograph of the microspherical TiO 2-x / C / FeMn-LHD S / g-C3N4 composite photo-Fenton catalyst. As can be seen from Figure 7, the sample presents a clear core-shell structure.

[0061] Figure 8 is an X-ray diffraction pattern of the microspherical TiO 2-x / C / FeMn-LHD S / g-C3N4 composite photo-Fenton catalyst. The material exhibits characteristic diffraction peaks of anatase TiO2 at 2θ of 25.3°, 37.8°, 48.0°, 55.1° and 68.8°, corresponding to (101), (004), (200), (211), (116) crystal faces, respectively, which shows that the structure characteristics of TiO2 are not affected by the reducing agent; the broad and weak diffraction peak at 21.5° is the diffraction peak of carbon corresponding to (002) crystal face, and the decrease in the intensity of the characteristic diffraction peak is due to the surface coating of LDH and g-C3N4; the characteristic diffraction peaks of FeMn-LDO are exhibited at 2θ of 24.2°, 31.4°, 37.5° and 41.4°, corresponding to (012), (104), (110) and (113) crystal faces, respectively, and the two diffraction peaks at 12.9° and 27.7° correspond to (100) and (002) crystal faces, which belong to the in-plane structure stacking and interplanar stacking reflection of the conjugated aromatic system of g-C3N4, further indicating that the material is successfully compounded.

[0062] Example 2

[0063] A microspherical TiO 2-x / C / FeMn-LDH S The preparation method of the g-C3N4 composite photo-Fenton catalyst comprises the following steps:

[0064] (1) 10 g of Ti(SO4)2 was weighed and added into a mixed solution of 2.5 g of urea and 50 mL of 95 wt% ethanol, and then the solution was uniformly mixed, and then the solution was transferred into a 150 mL polytetrafluoroethylene-lined reaction kettle, and reacted at 140°C for 12 h, and then naturally cooled to room temperature, and then centrifuged by a centrifuge, and then the product was washed several times with deionized water and ethanol respectively, and then vacuum dried at 80°C for 12 h to obtain the product TiO 2-x hollow microspheres; the prepared hollow microspheres were added into a 0.1 mol / L NaBH4 solution, and then magnetically stirred at room temperature for 60 min, and finally washed with deionized water and dried to obtain TiO 2-x hollow microspheres.

[0065] (2) 5 g of TiO 2-x hollow microspheres were placed in 20 mL of a dilute nitric acid solution with a concentration of 0.0015 mol / L, and then ultrasonically treated for 10 min, and then dispersed in 70 mL of a sodium carboxymethyl cellulose solution with a concentration of 1.09 mol / L after centrifugation (the mass ratio of TiO 2-x hollow microspheres to sodium carboxymethyl cellulose was 1:4), and then ultrasonically treated for 20 min, and then vacuum filtered, and then the TiO 2-x hollow microspheres coated with sodium carboxymethyl cellulose were transferred into a muffle furnace, heated to 600°C at a heating rate of 5°C / min and kept for 5 h, and then naturally cooled to room temperature, and then the product was washed several times with deionized water and ethanol respectively, and then centrifuged by a centrifuge, and then vacuum dried at 85°C for 10 h to obtain the product microspherical TiO 2-x / C, and the SEM characterization results of the product are shown in Fig. 2c and Fig. 3.

[0066] (3) 25 mL of Fe(NO3)3·9H2O with a concentration of 1.0 mol / L and 25 mL of Mn(NO3)2·4H2O with a concentration of 1.0 mol / L were mixed to form a salt solution, and then 7 g of microspherical TiO 2-x / C were ultrasonically treated for 20 min, and then uniformly stirred; 0.03 mol of NaOH and 0.015 mol of Na2CO3 were dissolved in 100 mL of water to form a mixed alkali solution, and then stirred for 30 min; the mixed alkali solution was added dropwise into the mixed salt solution, and then the pH was kept stable at 9.5, and then ultrasonically treated for 30 min after the addition was completed, and then reacted at 150°C for 5 h under oil bath conditions, and then naturally cooled to room temperature, and then centrifuged by a centrifuge, and then the product was washed several times with deionized water and ethanol respectively, and then vacuum dried at 70°C for 3 h to obtain the product microspherical TiO 2-x / C / FeMn-LDH S.

[0067] (4) 3 g of the microspherical TiO 2-x / C / FeMn-LHD S , 3 g of g-C3N4 nanosheets were dissolved in 50 mL of deionized water, ultrasonicated for 2 min, and stirred at 35℃ for 3 h. The product was washed several times with water and ethanol, respectively, and placed in an oven at 60℃ for aging for 12 h to obtain microspherical TiO 2-x / C / FeMn-LHDs / g-C3N4 composite photo-Fenton catalyst.

[0068] Example 3

[0069] A microspherical TiO 2-x / C / FeMn-LHD S / g-C3N4 composite photo-Fenton catalyst, comprising the following steps:

[0070] (1) 10 g of Ti(SO4)2 was weighed and added to a mixed solution of 2.5 g of urea and 50 mL of 95 wt% ethanol, mixed uniformly, and then the solution was transferred to a 150 mL polytetrafluoroethylene-lined reaction kettle, reacted at 130℃ for 12 h, naturally cooled to room temperature, centrifuged with a centrifuge, and the product was washed several times with deionized water and ethanol, respectively, and dried at 80℃ under vacuum for 12 h to obtain the product TiO2 hollow microspheres; the prepared hollow microspheres were added to a 0.1 mol / L NaBH4 solution, magnetically stirred at room temperature for 60 min, and finally washed with deionized water and dried to obtain TiO 2-x hollow microspheres.

[0071] (2) 5 g of TiO 2-x hollow microspheres were placed in 20 mL of 0.0015 mol / L dilute nitric acid solution, ultrasonicated for 10 min, and after centrifugation, they were dispersed in 80 mL of 1.19 mol / L sodium carboxymethyl cellulose solution (the mass ratio of TiO 2-x hollow microspheres to sodium carboxymethyl cellulose was 1:5), ultrasonicated for 20 min, vacuum filtered, and the TiO 2-x hollow microspheres coated with sodium carboxymethyl cellulose were transferred to a muffle furnace, heated to 500℃ at a heating rate of 5℃ / min and kept for 5 h, naturally cooled to room temperature, washed several times with deionized water and ethanol, respectively, centrifuged with a centrifuge, and dried at 85℃ under vacuum for 10 h to obtain the product TiO 2-x / C hollow microspheres. The SEM characterization results of the product are shown in Figure 2d.

[0072] (3) Sonicate 25 mL of a 1.0 mol / L Fe(NO3)3·9H2O and 50 mL of a 2.0 mol / L Mn(NO3)2·4H2O mixed salt solution for 20 min, then add 7 g of microspheres of TiO2. 2-x / C, stir evenly; dissolve 0.03 mol NaOH and 0.015 mol Na2CO3 in 100 mL of water and stir for 30 min to form a mixed alkaline solution; add the mixed alkaline solution dropwise to the mixed salt solution, keeping the pH stable at 10, and sonicate for 20 min after the addition is complete. React at 150℃ for 3 h under oil bath conditions, cool naturally to room temperature, centrifuge, wash the product several times with deionized water and ethanol, and vacuum dry at 70℃ for 3 h to obtain the product, microsphere TiO2. 2-x / C / FeMn-LDH S .

[0073] (4) 3g of microsphere TiO 2-x / C / FeMn-LDH S 4 g of g-C3N4 nanosheets were dissolved in 50 mL of deionized water, sonicated for 2 min, and stirred at 35 °C for 3 h. The product was washed several times with deionized water and ethanol, and aged overnight in an oven at 70 °C to obtain microspheres of TiO2. 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst.

[0074] Comparative Example 1

[0075] Except in step (2), where glucose is used as the carbon source, TiO2... 2-x The mass ratio of hollow microspheres to glucose is 1:3, of which TiO2... 2-x 5 g of hollow microspheres were used, along with 40 mL of glucose aqueous solution at a concentration of 2.08 mol / L. The pyrolysis carbonization temperature was 150 °C, and the time was 5 h. The remaining steps were the same as in Example 1. The SEM characterization results of the product are shown in Figure 4.

[0076] Comparative Example 2

[0077] Except for step (2), TiO 2-x The mass ratio of hollow microspheres to sodium carboxymethyl cellulose was 1:2, with the sodium carboxymethyl cellulose solution comprising 70 mL of 0.54 mol / L solution. The remaining parameters were the same as in Example 1. The SEM characterization results of the product are shown in Figure 2a.

[0078] Comparative Example 3

[0079] Except for step (2), TiO 2-xThe mass ratio of hollow microspheres to sodium carboxymethyl cellulose was 1:6, wherein the volume of the sodium carboxymethyl cellulose solution was 70 mL, and the concentration was 1.63 mol / L. The rest was the same as in Example 1. The SEM characterization result of the product is shown as e in FIG. 2.

[0080] Comparative Example 4

[0081] Except that step (1) was not included, i.e., TiO2 hollow microspheres were directly used instead of TiO 2-x The hollow microspheres were subjected to the operations of steps (2) to (4), and the rest was the same as in Example 1, to obtain the product, i.e., microspherical TiO2 / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst.

[0082] FIG. 9 is a Tauc diagram of the microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 and microspherical TiO2 / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst. It can be seen from FIG. 9 that: the absorption edge of the microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 is red-shifted, and the optical band gap is 2.82 eV, which is lower than 2.7 eV of g-C3N4 and 3.2 eV of TiO2, indicating that the modified composite material has a wider light absorption range than single g-C3N4 and TiO2. Meanwhile, the optical band gap is still dominant compared with the un-reduced catalyst, indicating that the reduced TiO 2-x The microspheres can make the composite material have a higher light response and light absorption range. The reduction of the band gap is related to the reduced Ti, which causes the electronic state vacancy band to rise, and the increase in the light absorption range may be due to the introduction of defects by Ti, which improves the absorption of photon energy.

[0083] FIG. 10 is a PL spectrum of the microspherical TiO 2-x / C / FeMn-LDH 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst. It can be seen from FIG. 10 that, within a certain range, the PL intensity gradually decreases with the increase of the concentration of sodium carboxymethyl cellulose, indicating that the carbon layer can inhibit the recombination of photo-generated electron-hole pairs in the transfer process, realize efficient transfer of photo-generated electrons, and thus improve the catalytic performance and efficiency.

[0084] The microspherical TiO 2-x / C / FeMn-LDH SThe products prepared in the Examples 1-4 and Comparative Examples 1-4 are used for removal of ammonia nitrogen and antibiotics in water. The specific operation is as follows: the microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 material, the microspherical TiO 2-x / C / FeMn-LDHs, the microspherical TiO 2-x / C, the TiO 2-x hollow microspheres, the microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4, the microspherical TiO 2-x / C and the microspherical TiO2 / C / FeMn-LDH prepared in Comparative Example 4 S / g-C3N4, 30 mg of each of the above materials is respectively placed in thirteen groups of 50 mL solutions containing ammonia nitrogen at a concentration of 50 mg / L and tetracycline at a concentration of 50 mg / L, numbered 1-13, and dark stirring is carried out for 30 min under light shielding to achieve adsorption and desorption equilibrium; after the dark stirring is completed, 1.5 mL of H2O2 solution is added, and catalytic degradation is carried out under light irradiation, and the reaction time is 30 min. The results are shown in Table 1:

[0085] Table 1: Degradation rates of catalysts prepared in the Examples and Comparative Examples on ammonia nitrogen and antibiotics in water

[0086] As can be seen from the results in Table 1, the microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 photo-Fenton catalyst, compared with TiO 2-x , can greatly improve the removal efficiency of ammonia nitrogen and lipophilic antibiotics in water. The microspherical TiO 2-x / C of Example 1 can greatly improve the removal efficiency of ammonia nitrogen and lipophilic antibiotics in water by preparing an amorphous carbon layer on the surface of TiO 2-x , improving the catalytic performance. The microspherical TiO 2-x / C / FeMn-LDH S further coats FeMn-LDH S on the surface of the carbon layer of TiO 2-x / C, forming a spherical and layered composite material, which significantly improves the specific surface area of the catalyst, improves the catalytic activity, and can also synergistically adsorb pollutants with the carbon layer, so that the removal efficiency of ammonia nitrogen and lipophilic antibiotics is greatly improved; the microspherical TiO 2-x / C / FeMn-LDHS The microspherical TiO 2-x / C / FeMn-LDH S The g-C3N4 photocatalyst has the advantages of combination of spherical structure and layered structure, heterojunction, carbon protection and stable oxygen vacancies, which significantly improves the electron transfer efficiency of the catalyst.

[0087] Comparative Example 1 uses glucose of the same mass ratio as Example 1 as a carbon source, and the obtained TiO 2-x / C and TiO 2-x / C / FeMn-LDH S The removal efficiency of ammonia nitrogen and lipophilic antibiotics in water by the g-C3N4 is lower than that of the TiO 2-x / C and TiO 2-x / C / FeMn-LDH S The g-C3N4, indicating that the selection of the carbon source has an important influence on the photocatalytic performance of the material, and the TiO 2-x The scanning electron microscope images of the / C material (shown in Fig. 4) and the TiO 2-x The scanning electron microscope images of the / C material (shown in Fig. 2b) microspherical TiO 2-x The surface morphology of the / C material can be compared, and the TiO 2-x The surface carbon layer of the / C material is thin, which may be due to the fact that glucose is a monosaccharide and has a lower carbon content than sodium carboxymethyl cellulose. The concentration of the sodium carboxymethyl cellulose solution in Comparative Example 2 is lower, resulting in the TiO 2-x The hollow microspheres are not completely covered with sodium carboxymethyl cellulose, and the obtained microspherical TiO 2-x The surface carbon layer of the / C material is unevenly distributed (shown in Fig. 2a), resulting in a photocatalytic performance lower than that of Examples 1-3. The concentration of the sodium carboxymethyl cellulose solution in Comparative Example 3 is higher, resulting in the TiO 2-x The hollow microspheres are not completely covered with sodium carboxymethyl cellulose, and the obtained microspherical TiO

[0088] The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. Microspherical TiO 2-x / C / FeMn-LDH S A preparation method of a microspherical TiO Comprising the following steps: (1) TiO2hollow microspheres as raw material, using in-situ chemical reduction method to prepare TiO 2-x Hollow microspheres, wherein 0.1≤x≤2; (2) Activating the hollow microspheres, coating the activated TiO 2-x microspheres with sodium carboxymethyl cellulose, pyrolyzing and carbonizing to obtain microspherical TiO 2-x microspheres, and then pyrolyzing and carbonizing to obtain microspherical TiO 2-x / C; the activating treatment comprises activating the hollow microspheres in a solution of HNO3 and H2O2 2-x ultrasonic treatment in a dilute acid solution; (3) The manganese-iron layered double hydroxide is prepared on the surface of the microspherical TiO 2-x / C by a coprecipitation method, to obtain the microspherical TiO 2-x / C / FeMn-LDH S ; (4) TiO 2-x / C / FeMn-LDH S and g-C3N4 by a chemical bath deposition method to obtain a microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst; the chemical bath deposition method comprises the following steps: dissolving TiO 2-x / C / FeMn-LDH S and g-C3N4 in deionized water, ultrasonic treatment, stirring reaction, and aging the reaction product overnight after washing to obtain a microspherical TiO 2-x / C / FeMn-LDH S / g-C3N4 composite photo-Fenton catalyst.

2. The production method according to claim 1, wherein In step (1), comprising one or more of the following features: (1a) The preparation method of the TiO2 hollow microspheres comprises: taking Ti salt as precursor, ethanol as solvent, and urea as organic additive, and carrying out hydrothermal reaction to prepare TiO2 hollow microspheres; (1b) The in-situ chemical reduction method comprises: adding TiO2hollow microspheres into a reducing agent solution, conducting a reduction reaction at room temperature, and obtaining TiO2hollow microspheres after washing and drying 2-x hollow microspheres.

3. The production method according to claim 2, wherein In step (1), comprising one or more of the following features: (1a1) The Ti salt is selected from any one of Ti(SO4)2, TiCl4, Ti(S2O7)2; (1a2) The molar ratio of the Ti salt to urea is 1:1-2; (1a3) The ratio of the mass of urea to the volume of ethanol in the urea ethanol solution formed by urea and ethanol is 0.02-0.05 g / mL; (1a4) The concentration of the ethanol is 95 wt%; (1a5) The reaction temperature of the hydrothermal reaction is 120-140℃, and the reaction time is 12-14 h; (1b1) The reducing agent is selected from any one or more of NaBH4, KBH4, H2C2O4; (1b2) The concentration of the reducing agent in the reducing agent solution is 0.1-0.5 mol / L; (1b3) Magnetic stirring is carried out during the reduction reaction; (1b4) The washing medium is deionized water; (1b5) The drying temperature is 60-80℃, and the drying time is 12-24 h.

4. The production method according to claim 1, wherein In step (2), comprising one or more of the following features: (2b) the carboxymethyl cellulose sodium is coated on the activated TiO 2-x The surface of the hollow microspheres comprises: the activated TiO 2-x The hollow microspheres are dispersed in a carboxymethyl cellulose sodium solution, so that the carboxymethyl cellulose sodium is coated on the activated TiO 2-x The surface of the hollow microspheres; (2c) The temperature of the pyrolysis is 400-600℃, and the pyrolysis time is 3-5 h; (2d) The pyrolysis carbonization product needs to be washed, centrifuged, and dried to obtain microspherical TiO 2-x / C.

5. The production method according to claim 4, wherein In step (2), comprising one or more of the following features: (2a1) The dilute acid solution is selected from any one of dilute hydrochloric acid, dilute nitric acid, dilute sulfuric acid, and hydrofluoric acid; (2a2) The concentration of the dilute acid solution is 0.0005-0.01 mol / L; (2b1) the TiO 2-x The mass ratio of the hollow microspheres to sodium carboxymethyl cellulose is 1:3-5. (2c1) The pyrolysis adopts programmed temperature rising, and the temperature rising speed is 5-10℃ / min; (2d1) The washing is sequentially carried out using deionized water and ethanol; (2d2) The temperature of the drying is 80-90℃, and the time is 10-12 h.

6. The production method according to claim 1, wherein In step (3), the co-precipitation method comprises the following steps: The mixed salt solution of ferric salt and manganese salt is ultrasonically treated, and then added dropwise into a mixed alkali solution of NaOH and Na2CO3, so as to keep the pH value at 9.5-10.5; after the dropwise addition is completed, microspherical TiO 2-x / C, and after the precipitation reaction is completed, the microspherical TiO 2-x / C / FeMn-LDH S is obtained after washing and drying.

7. The production method according to claim 6, wherein Comprising one or more of the following features: (3a1) In step (3), the molar ratio of Fe 3+ , Mn 2+ in the mixed salt solution is 1-2: 1-5. (3a2) In step (3), the mass ratio of the trivalent iron salt to the microspherical TiO 2-x / C is 1-2:

1. (3a3) In step (3), the temperature of the precipitation reaction is 150-170℃, and the reaction time is 3-5 h; (3a4) In step (3), the ultrasonic treatment time is 10-20 min; (3a5) In step (3), the washing is sequentially carried out using deionized water and ethanol; (3a6) In step (3), the drying mode is vacuum drying, the drying temperature is 50-70℃, and the drying time is 2-4 h; (4a1) In step (4), the TiO 2-x / C / FeMn-LDH S , the mass ratio of g-C3N4 is 1:1-3; (4a2) In step (4), the ultrasonic treatment time is 10-30 min; (4a3) In step (4), the washing is sequentially carried out using deionized water and ethanol; (4a4) In step (4), the aging temperature is 55-65℃, and the aging time is 12-24 h.

8. A microspheroidal TiO 2-x / C / FeMn-LDH S / C / FeMn-LDH / C / FeMn-LDH 9. The application of the composite photo-Fenton catalyst in claim 8 in catalyzing the degradation of ammonia nitrogen and lipophilic antibiotics in wastewater or sludge tail water.

10. Use according to claim 9, wherein The antibiotic includes a quinolone antibiotic, a macrolide antibiotic, a tetracycline antibiotic, or a sulfonamide antibiotic. The antibiotic includes a quinolone antibiotic, a macrolide antibiotic, a tetracycline antibiotic, or a sulfonamide antibiotic.

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